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Stone, Gregory M. "Beneficial Reuse of Corrugated Paperboard in Civil Engineering Applications." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/691.
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Abstract
Beneficial Reuse of Corrugated Paperboard in Civil Engineering Applications
Gregory Michael Stone
An investigation was conducted to explore the potential for reuse of corrugated paperboard. Corrugated paperboard represents a large fraction of the municipal solid waste generated and discarded in the United States. Alternative applications for reuse can provide a significant benefit by reducing the volume of waste being disposed and by reducing the use of raw materials. Four civil engineering applications were examined for potential beneficial reuse of corrugated paperboard: slurry trench construction, vertical drilling, directional drilling, and controlled low strength materials (CLSM).
For the purpose of this project, corrugated paperboard was pulped and added to bentonite slurry or CLSM mixtures. Bentonite slurry mixtures were tested for viscosity, density, filtrate loss, and permeability. The behavior of the bentonite slurries was greatly influenced by interaction and interlocking of corrugate fibers; in general resulting in increased viscosity, filtrate loss, and permeability and decreased density. CLSM mixtures were tested for flow consistency, unit weight, air content, and compressive strength. CLSM mixtures prepared with corrugated paperboard showed an increased water demand due to high absorption of the corrugate. The higher water content was a significant factor contributing to decreased unit weight and compressive strength. CLSM mixtures containing corrugated paperboard also exhibited increased air contents, possibly due to entrapment of air within the corrugate pulp.
Corrugated paperboard was used to successfully replace up to 27% of bentonite for slurry trench applications, 60% of bentonite for vertical drilling applications, and 59% of bentonite for directional drilling applications while maintaining acceptable engineering properties. For CLSM mixtures up to 1% of fine aggregate was replaced with corrugated paperboard while maintaining satisfactory engineering properties.
Incorporation of corrugated paper board into bentonite slurry, CLSM, and drilling fluid applications provides a viable option for beneficial reuse.
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Deacon, M. "Distributed Collaboration: Engineering Practice Requirements." Thesis, Linkt to the online version, 2007. http://hdl.handle.net/10019/755.
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Park, Suwan. "A systems approach to strategic planning for the Civil Engineering Department." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08222008-063414/.
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Cronje, Mercia. "Engineering process model: Detection of cycles and determination of paths." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2376.
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Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2006.In order to plan the engineering work of large construction projects efficiently, a model of the engineering process is required. An engineering process can be modelled by sets of persons, tasks, datasets and tools, as well as the relationships between the elements of these sets. Tasks are more often than not dependent on other tasks in the engineering process. In large projects these dependencies are not easily recognised, and if tasks are not executed in the correct sequence, costly delays may occur. The homogeneous binary relation “has to be executed before” in the set of tasks can be used to determine the logical sequence of tasks algebraically. The relation can be described by a directed graph in the set of tasks, and the logical sequence of tasks can be determined by sorting the graph topologically, if the graph is acyclic. However, in an engineering process, this graph is not necessarily acyclic since certain tasks have to be executed in parallel, causing cycles in the graph. After generating the graph in the set of tasks, it is important to fuse all the cycles. This is achieved by finding the strongly connected components of the graph. The reduced graph, in which each strongly connected component is represented by a vertex, is a directed acyclic graph. The strongly connected components may be determined by different methods, including Kosaraju’s, Tarjan’s and Gabow’s methods. Considering the “has to be executed before” graph in the set of tasks, elementary paths through the graph, i.e. paths which do not contain any vertex more than once, are useful to investigate the influence of tasks on other tasks. For example, the longest elementary path of the graph is the logical critical path. The solution of such path problems in a network may be reduced to the solution of systems of equations using path algebras. The solution of the system of equations may be determined directly, i.e. through Gauss elimination, or iteratively, through Jacobi’s or Gauss-Seidel’s methods or the forward and back substitution method. The vertex sequence of an acyclic graph can be assigned in such a way that the coefficient matrix of the system of equations is reduced to staggered form, after which the solution is found by a simple back substitution. Since an engineering process has a start and an end, it is more acyclic than cyclic. Consequently we can usually reduce a substantial part of the coefficient matrix to staggered form. Using this technique, modifications of the solution methods mentioned above were implemented, and the efficiency of the technique is determined and compared between the various methods.
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Day, Peter William. "A contribution to the advancement of geotechnical engineering in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79868.
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Thesis (DEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Geotechnical engineering is a relatively young field of engineering and one in which there are still many unanswered questions and gaps in our knowledge. Added to this, the geotechnical materials on each new site on which geotechnical work is undertaken are the unique product of many influences including geology, geomorphology, climate, topography, vegetation and man. There is thus plenty of scope for innovation. This dissertation describes the contributions made to Geotechnical Engineering in South Africa by the Candidate over a period of close on 40 years. It describes the three-step process followed in the majority of these contributions. Step one is the identification of a problem that requires investigation, the application of new techniques or simply the consolidation of existing knowledge. Step 2 is the investigation of the problem and the development of a solution. Step 3 is sharing the outcome of this work with the profession by means of publications, by presentations at seminars and conferences or by incorporation into standards / codes of practice. Part 1 of the dissertation describes the exciting environment in which geotechnical engineers operate. This environment is characterised by openness and cooperation between practitioners of geotechnical engineering, be they geotechnical engineers, engineering geologists, contractors, suppliers or academics. This part also explores the parallels in the roles played by academics and practitioners and how each can contribute to the advancement and dissemination of knowledge. Part 2 describes contributions made in various fields including problem soils (dolomites, expansive clays, uncompacted fills, etc.), lateral support, pile design and construction, health and safety, and cooperation with international organisations. Part 3 describes the Candidate's involvement in the introduction of limit states geotechnical design into South African practice culminating in the drafting of SANS 10160-5 on Basis of Geotechnical Design and Actions. It also describes the Candidate's work with the ISSMGE Technical Committee TC23 dealing with limit states design. Part 4 deals with the Candidate's contribution to other codes and standards and his role on various committees of the Engineering Council of South Africa and the South African Bureau of Standards. The final part of the dissertation provides an overview of the process followed in making such contributions, highlighting the role played by curiosity and a desire to share the knowledge gained with others in the profession. It continues by identifying work that still needs to be done in many of the areas where contributions have been made and concludes with a statement of what the candidate would still like to achieve during the remainder of his career. The Candidate gratefully acknowledges the generous opportunities afforded to him by his colleagues at work and the invaluable guidance and mentorship received from fellow professionals in academia and practice.
AFRIKAANSE OPSOMMING: Geotegniese ingenieurswese is 'n relatiewe jong wetenskap en een met vele kennisgapings en waarin daar nog talle vrae onbeantwoord bly. Daarby is geotegniese materiale uniek tot elke terrein waarop werk aangepak word en die produk van 'n kombinasie van prosesse; insluitend geologie, geomorfologie, klimaats toestande, topografie, plantegroei en menslike aktiwiteite. Daar is dus nog ruim geleentheid vir innoverende bydraes. Hierdie verhandeling beskryf die Kandidaat se bydraes tot Geotegniese Ingenieurswese in Suid-Afrika oor die afgelope 40 jaar. Dit beskryf 'n drie-voudige benadering wat in die meeste van die bydraes gevolg is. Die eerste stap is om die probleem te definieer en te omskryf in terme van die ondersoek wat geloods moet word, asook die noodsaaklikheid vir die ontwikkeling van nuwe tegnologie teenoor die konsolidasie van bestaande inligting. Tydens die tweede stap word die probleem ondersoek en 'n oplossing ontwikkel. Die derde stap is om die resultate te deel met die geotegniese bedryf by wyse van publikasies, voorleggings by konferensies en seminare, en insluiting in praktykkodes en standaarde. Deel 1 beskryf die opwindende werksomstandighede waarbinne geotegniese ingenieurs hul bevind. Dit word geken aan die ope samewerking tussen belanghebbende partye; onder andere ingenieurs, ingenieursgeoloë, kontrakteurs, verskaffers en akademici. Deel 1 beklemtoon ook die parallelle rolle wat vertolk word deur akademici en praktiserende ingenieurs en hoe beide partye bydraes maak tot die ontwikkeling en verspreiding van tegnologie. Deel 2 beskryf die Kandidaat se bydraes tot verskeie navorsingsvelde; waaronder probleemgrondtoestande (dolomiet, swellende kleie, ongekonsolideerde opvullings ens.), laterale ondersteuning, ontwerp en konstruksie van heipale, beroepsveiligheid, en samewerking met internasionale organisasies. Deel 3 beskryf die Kandidaat se betrokkenheid by die bekendstelling van limietstaat geotegniese ontwerp in die Suid-Afrikaanse bedryf wat uitgeloop het op die samestelling van SANS 10160-5 Basis of Geotechnical Design and Actions. Dit beskryf ook die Kandidaat se samewerking met die ISSMGE Technical Committee TC23 wat te make het met limietstaat ontwerp. Deel 4 beskryf die Kandidaat se bydraes tot ander kodes en standaarde en die rolle wat hy vertolk het op verskeie komitees van die Suid-Afrikaanse Raad vir Ingenieurswese asook van die Suid-Afrikaanse Buro van Standaarde. Die laaste deel van die verhandeling bied „n oorsig oor die proses wat gevolg is in bostaande bydraes met die klem op die rol van weetgierigheid en die begeerte om sulke kennis te deel met ander belanghebbendes. Om af te sluit, identifiseer die Kandidaat oorblywende tekortkominge in baie van die vraagstukke waar hy bydraes gelewer het en gee 'n opsomming van wat hy graag nog sal wil bereik tydens die verdere verloop van sy loopbaan. Die Kandidaat gee met dank erkenning aan sy kollegas vir die ruim geleenthede wat hom gebied is en die waardevolle leiding en mentorskap wat hy ontvang het van mede praktiserende ingenieurs en akademici.
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Welling, Gary E. "Engineering Performance of Polymer Amended Soils." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/856.
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A laboratory test program was undertaken to evaluate a series of engineering properties over a range of soil types; amendment types and addition rates; and moisture contents to enhance understanding of the engineering significance of polymer amendment. Four soils were manufactured and tested with varying ranges of fines and plasticity. A proprietary elastic copolymer was tested at addition rates of 0.5% to 2.5% (dry weight basis). Cement was tested at addition rates of 1% to 4%. Lime was tested at an 8% addition rate. Water addition rates ranged from 4% dry of optimum to 4% wet of optimum. Engineering properties determined throughout the test program included dry unit weight / moisture content relationships through compaction tests; shear strength through unconfined compression strength tests and direct shear tests; durability through freeze-thaw and wet-dry durability tests; and stiffness through resilient modulus tests and through interpretation of the unconfined compression and direct shear test results.
The addition of polymer altered the optimum moisture content of the soils. Change in optimum moisture content ranged from 0.51 to 1.27 times the control water demand. The dry unit weight of polymer amended specimens ranged from 0.97 to 1.01 times their respective control dry unit weight. The peak strength of polymer amended specimens ranged from 1.02 to 18.4 times the control strength. The peak wet-dry and freeze-thaw durability of polymer amended specimens ranged from 6.8 to 10.8 times the control durability. The addition of polymer increased the peak initial stiffness of specimens to approximately 3 times the control stiffness. However, the stiffness was reduced to 0.68 times the control stiffness with dynamic repeated loading through the resilient modulus test.
The polymer addition rate required to achieve peak engineering performance ranged from 0.5% to 2.5%, based on soil type. Polymer modified the engineering properties of soil through physical bonding. The amount of polymer required to modify the engineering properties was directly related to specific surface and soil particle coating thickness. It was determined that polymer amendment had an optimal addition rate that resulted in the greatest increase in engineering parameters. The addition rate was optimum when polymer was applied at rates high enough to sufficiently coat all soil particle surfaces, but at rates low enough that it did not cause additional particle separation.
Overall, polymer amendment of soil improved or maintained all tested engineering parameters, except the resilient modulus, of all soils. Polymer amended soils displayed a reduced performance compared to cement amended soils, and an improved performance compared to lime amended soils.
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Dithinde, Mahongo. "Characterisation of model uncertainty for reliability-based design of pile foundations." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/21612.
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Dissertation (PhD)--University of Stellenbosch, 2007.ENGLISH ABSTRACT: To keep pace with international trends, the introduction of geotechnical limit state design in South Africa is inevitable. To pave the way for implementation of limit state pile design in the country, the study quantifies model uncertainty in the classic static pile design formula under the Southern African geologic environment. The generated model uncertainty statistics are used to calibrate partial resistance factors in a reliability-based design framework. A series of pile performance predictions by the static formula are compared with measured performances. To capture the distinct soil types for the geologic region of Southern Africa as well as the local pile design and construction experience base, pile load tests and associated geotechnical data from the Southern African geologic environment are used. The methodology of collecting, compiling, and analyzing the pile load tests to derive the measured ultimate pile capacities is described. To facilitate the computation of the theoretical capacities, the site specific geotechnical data in the database are transformed to the desired engineering soil properties through well established empirical correlations. For a given pile test case, model uncertainty is presented in terms of a model factor computed as the ratio of the measured to the theoretical capacity, leading to n realisations of the model factor. To facilitate further interpretation and generalisation of the model factor realisation data, statistical analysis is carried out. The statistical analysis comprises of graphical representation by histograms, outliers detection and correction of erroneous values, and using the corrected data to compute the sample moments (mean, standard deviations, skewness and kurtosis) needed in reliability analysis. The analyses demonstrate that driven piles depict higher variability compared to bored piles irrespective of materials type. Furthermore, for a given pile installation method (driven or bored) the variability in non-cohesive materials is higher than that in cohesive materials. In addition to the above statistics, reliability analysis requires the theoretical probability distribution for the random variable under consideration. Accordingly it is demonstrated that the lognormal distribution is the most appropriate theoretical model for the model factor. Another key basis for reliability theory is the notion of randomness of the basic variables. To verify that the variation in the model factor is not explainable by deterministic variations in the database, an investigation of correlation of the model factor with underlying pile design parameters is carried out. It is shown that such correlation is generally weak. Correlation can have a significant impact on the calculated reliability index if not accounted for. Accordingly, the effects of the exhibited correlation is investigated through an approach based on regression theory in which systematic effects of design parameters are taken into account (generalised model factor). The model factor statistics from the conventional approach and those from the generalised model factor approach are used to determine reliability indexes implied by the current design practice. It is demonstrated that no significant improvement in values of the reliability indexes is gained by taking into account the effects of the weak correlation. The model factor statistics derived on the basis of the standard model factor approach are used to calibrate resistance factors. Four first order reliability methods are employed for the calibration of resistance factors. These include; the Mean Value First-Order Second Moment approach, an Approximate Mean Value First-Order Second Moment approach, the Advanced First-Order Second Moment approach using Excel spreadsheet, and the Advanced First-Order Second Moment approach (design point method). The resistance factors from the various calibration methods are presented for the target reliability index values of 2.0, 2.5, and 3.0. The analyses of the results demonstrate that for a given target reliability index, the resistance factors from the different methods are comparable. Furthermore, it is shown that for a given material type, the resistance factors are quite close irrespective of the pile installation method, suggesting differentiation of partial factors in terms of materials types only. Finally, resistance factors for use in probabilistic limit state pile design in South Africa are recommended.
AFRIKAANSE OPSOMMING: Ten einde in pas te bly met internasionale neigings, is dit onafwendbaar dat geotegniese limietstaat-ontwerp in Suid Afrika ingevoer word. Ter voorbereiding vir die plaaslike toepassing van limietstaatontwerp op heipale, kwantifiseer hierdie ondersoek onsekerheid rondom die model vir klassieke statiese heipaalontwerpformules in die Suid Afrikaanse geologiese omgewing. Die statistiek van modelonsekerheid wat gegenereer is, word gebruik om parsiële weerstandsfaktore in ’n betoubaarheid-gebasseerde ontwerpraamwerk te kalibreer. ’n Reeks voorspellings van die gedrag van heipale volgens die statiese formules word vergelyk met die gemete gedrag. Om die kenmerkende grond-tipes in die geologiese gebied van Suidelike Afrika sowel as die plaaslike ondervinding met heipaalontwerp en - konstruksie vas te lê, word heipaaltoetse en die gassosieerde geotegniese data vanuit hierdie geologiese omgewing gebruik. Die metodiek vir die versameling, saamstelling en analise van heipaaltoetse om uiterste kapasiteite daarvan te bepaal, word beskryf. Terreinspesifieke geotegniese data in die databasis word getransformeer na die vereisde ingenieurseienskappe volgens gevestigde empiriese korrelasies. Vir ’n gegewe heipaaltoets word modelonsekerheid weergegee in terme van ’n modelfaktor wat bereken word as die verhouding van die gemete tot die teoretiese kapasiteit waaruit n uitkomstes van die modelfaktor dus gegenereer word. Om verdere interpretasie en veralgemening van die modelfaktordata te vergemaklik, word ’n statistiese analise daarop uitgevoer. Die statistiese analise bestaan uit grafiese voorstellings deur middel van histogramme, uitkenning van uitskieters en verbetering van foutiewe waardes, waarna die statistiese momente (gemiddeld, standaardafwyking, skeefheid en kurtose) vir gebruik in betroubaarheidsanalise bereken word. Volgens die analises toon ingedrewe heipale ’n groter veranderlikheid as geboorde pale, ongeag die grondtipe. Verder is die veranderlikheid van heipale in kohesielose materiale hoër as in kohesiewe materiale, ongeag die installasiemetode (ingedrewe of geboor). Bykomend tot bogemelde statistiek, vereis betroubaarheidsanalise die teoretiese waarskynlikheidsdistribusie van die ewekansige veranderlike onder beskouing. Ooreenkomstig word illustreer dat die log-normale verspreiding die mees toepaslike verspreiding vir die modelfaktor is. ’n Verdere sleutelvereiste vir betroubaarheidsteorie is die mate van ewekansigheid van die basiese veranderlikes. Om te bepaal of die variasie in die modelfaktor nie deur deterministiese veranderlikes in die databasis verduidelik kan word nie, word ’n ondersoek na die korrelasie van die modelfaktor met onderliggende heipaalontwerpfaktore uitgevoer. Sodanige korrelasie is in die algemeen as laag bevind. Korrelasie kan ’n belangrike invloed op die berekende betroubaarheidsindeks hê indien dit nie in ag geneem word nie. Dienooreenkomstig word die effek van die getoonde korrelasie ondersoek met behulp van die metode van regressie-analise waarin sistematiese effekte van ontwerpparameters in berekening gebring word (veralgemeende modelfaktor). Die modelfaktorstatistiek wat volg uit die konvensionele benadering en dié van die veralgemeende benadering word gebruik om betroubaarheidsindekse te bepaal wat deur die bestaande ontwerppraktyk geïmpliseer word. Die bevinding is dat daar nie ’n noemenswaardige verbetering in die waardes van die betroubaarheidsindekse is wanneer die effek van die swak korrelasie in berekening gebring word nie. Die statistiek van die modelfaktor wat afgelei is volgens die standaardbenadering word gebruik om die weerstandsfaktore te kalibreer. Vier eerste-orde betroubaarheidsmetodes word gebruik om die weerstandsfaktore te kalibreer, naamlik die Gemiddelde Waarde Eerste-Orde Tweede Moment benadering, die Benaderde Gemiddelde Waarde Eerste-Orde Tweede Moment benadering, die Gevorderde Eerste-Orde Tweede Moment benadering waarin ’n Excel sigblad gebruik word en die Gevorderde Eerste-Orde Tweede Moment benadering (die ontwerppuntmetode). Die weerstandsfaktore vanaf die verskillende kalibrasiemetodes word weergegee vir waardes van 2.0, 2.5 en 3.0 van die teikenbetroubaarheidsindeks. ’n Ontleding van die resultate toon dat vir ’n gegewe teiken betroubaarheidsindeks die weerstandsfaktore vanaf die verskillende metodes vergelykbaar is. Verder word getoon dat vir ’n gegewe grondsoort, die weerstandsfaktore vir verskillende metodes van installasie van die heipaal nie veel verskil nie. Dit wil dus voorkom asof parsiële faktore in terme van die grondsoort uitgedruk kan word. Ten slotte word weerstandsfaktore vir gebruik in plastiese limietstaatontwerp van heipale in Suid Afrika aanbeveel.
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Murray, Alexander J. "Modeling Artificial Groundwater Recharge in the Santa Rosa Creek Watershed." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2140.
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The Santa Rosa Creek Watershed is an approximately 48 mi2 large watershed located on the central coast of California. This watershed drains to the Pacific Ocean through Santa Rosa Creek as it passes through agricultural land and the town of Cambria. Historically the groundwater within the Santa Rosa Creek Watershed has been used for irrigation, municipal and domestic uses, and the creek is critical habitat steelhead trout. During dry years, there is less water for all uses. When low groundwater levels occur, water can be drawn out of the creek and into the soil, drying out steelhead habitat. Seven agricultural operators within the Santa Rosa Creek Watershed are working with a local non-profit to improve sustainability of the aquifer through artificial groundwater recharge. One of these projects includes the use of a recharge basin. This study was conducted to understand the impacts of that recharge basin on the groundwater surrounding it as well as to evaluate the site’s potential for other recharge methods. The groundwater within the site of interest was modeled using GMS to calculate head values, to determine flow directions, and to determine timings. Three different hydrogeologic layers were used to simulate an upper unconfined zone, a clay confining layer, and a confined zone. The model was calibrated to known groundwater head values throughout the site. ArcMap was used to organize and preprocess data that went into the GMS model. Elevation, hydrologic soil characteristics, boundary heads, recharge rates, evapotranspiration rates, and well locations and pumping rates datasets were all preprocessed and imported into GMS. The model showed that the water from the recharge basin does not percolate into the underlying groundwater aquifer, but it flows out of the upper unconfined layer and into the creek over time. This is caused primarily by a low hydrologic conductivity confined aquifer in the northern section of the site as well as a confining clay layer underneath the unconfined top layer. According to the model, the site may not be feasible for artificial groundwater recharge in the northern portion, but there is potential for recharge in the southern area. Further data collection could improve the model to support or dispute these findings.
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Burroughs, Gary Leslie. "The response to environmental economic drivers by civil engineering contractors in South Australia." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09ENV/09envb972.pdf.
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Bibliography: leaves 91-93. Examines the response of two civil engineering construction contractors in South Australia to environmental economic conditions and market requirements using primarily an action research methodology whilst the researcher was engaged as the environmental manager at both corporations.
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Mitchell, Ryan. "A WANFIS Model for Use in System Identification and Structural Control of Civil Engineering Structures." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-theses/1165.
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With the increased deterioration of infrastructure in this country, it has become important to find ways to maintain the strength and integrity of a structure over its design life. Being able to control the amount a structure displaces or vibrates during a seismic event, as well as being able to model this nonlinear behavior, provides a new challenge for structural engineers. This research proposes a wavelet-based adaptive neuro- fuzzy inference system for use in system identification and structural control of civil engineering structures. This algorithm combines aspects of fuzzy logic theory, neural networks, and wavelet transforms to create a new system that effectively reduces the number of sensors needed in a structure to capture its seismic response and the amount of computation time needed to model its nonlinear behavior. The algorithm has been tested for structural control using a three-story building equipped with a magnetorheological damper for system identification, an eight-story building, and a benchmark highway bridge. Each of these examples has been tested using a variety of earthquakes, including the El-Centro, Kobe, Hachinohe, Northridge, and other seismic events.
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Strasheim, Jacobus Alexander van Breda. "A relation-based approach to Engineering Management Systems." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1328.
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Thesis (PhD (Civil Engineering))--University of Stellenbosch, 2007.The primary goal of this thesis is to indicate how systems theory and engineering process modelling can be applied to provide models for consulting engineering service business enterprises. The typical management systems used for these businesses are investigated to determine the application of systems and process models. The motivation for this study is based on the fact that integrated management systems for consulting engineering practices are presently based on selective business analysis and process modelling that has evolved over time, as reported in a survey and study by Smit [110]. Furthermore, current engineering management systems are simply computer implementations of management procedures based on techniques that were developed to solve problems in the absence of the computational capabilities of the modern computer. To rectify this, a fundamental approach to analyse the business and management functions using systems theory and engineering process modelling techniques is required, which has not been attempted to date. This study develops and demonstrates the application of fundamental analysis in consulting engineering enterprise management and reviews advantages that can be obtained from using this approach. It is shown that the mathematical Algebra of Relations and associated Graph Theory provide the mathematical basis on which management problems can be treated systematically. Since these fields of mathematics are well developed and very broad, the essential parts of the theories are identified. Thereupon, the application of the very abstract mathematical concepts to two important and typical engineering management problems are developed, which represents the core contribution of the dissertation. The study is developed and presented in two parts and an addendum: 1. The first part provides an overview of the necessary mathematical theory required to support development of business models. 2. Management systems theory and relation- and graph theory-based engineering process modelling techniques are applied in this part to build generic enterprise models and data processing models. These models provide inputs for the management processes of professional service business enterprises. The outcome of the modelling and analysis is a set of database models with reporting functionality, to be used in the management process. A demonstration of technology available for development of the models and techniques, described in the previous part, is undertaken in this part. Generic implementations of database models and reporting techniques for systems which deal with management data in a consulting engineering business are developed, described and demonstrated. 3. In the addendum to the study, typical models and system functionality needed to support the management functions of the consulting engineering service business are identified. These management functions include: • Business strategy and long term planning • Marketing and promotion • Finance, including bookkeeping and auditing • Personnel • Facilities management and document management • Logistics, i.e., management of resources required for the business to operate • Knowledge management • Production management, i.e., management of the execution of project work • Administration • Risk management Production management can use the engineering process model approach, modelling the management of tasks, persons, datasets and tools as these are applied to the consulting engineering business. Sample subsystems to support selected management functions are identified and analysed. The integration of these systems with commercially available systems to support accounting and management reporting can follow from this analysis. The study contributes to the body of knowledge in the field of engineering management by providing insights into the application of a specific branch of mathematics to provide fundamental solutions to engineering management problems. It also shows how these solutions are mapped to the computer, and describes available information techniques and technology to support the mapping. The outcome is a document setting out the theory required to develop robust enterprise management systems, the development and demonstration of technology required to do this and, as an addendum, a high level specification of business and management system functionality required for the professional engineering service business.
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Abutin, Megan P. "Effects of Using Clay Nanoparticles as a Soil Amendment to Remove Nitrate from Stormwater." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1908.
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Development of urban areas continues to increase, disrupting the natural ecosystem and the pathways for water to drain into downstream water bodies. As the amount of impervious area increases, pollutants can accumulate on the surface and enter the water cycle by stormwater. In most cities, the stormwater flows into a storm drain that is discharged into a water body. Low Impact Development technology has been developed to treat stormwater prior to discharge downstream. A bioretention cell is used to treat stormwater pollutants such as nitrate, phosphorus, total suspended solids, and metals. Past research has indicated that the removal efficiency of nitrate by bioretention cells greatly varies from a 75% reduction in nitrate concentration to the addition of nitrate in the effluent from leaching of the bioretention cell. It is important to remove nitrate from water because it can cause negative environmental and human effects. Excess nitrate in the environment can lead to eutrophication, resulting in the death of fish. If ingested by infants, nitrate can cause “blue baby syndrome” leading to death. One area of study that focuses on the removal of nitrate from stormwater is maximizing the efficiency of the designed soil media. The addition of a clay amendment could lead to higher removal efficiencies. The use of clay nanoparticles, or nanoclays, can maximize the amount of surface area available for adsorbance potentially increasing the amount of nitrate removed from water. The goal of this study was to identify a nanoclay with high adsorbance by testing its nitrate removal efficiency and then determining if it would be feasible to add to a bioretention cell by calculating the hydraulic conductivity to compare to industry design values. This study analyzed a montmorillonite clay, a bentonite nanoclay, and a pre-modified trimethyl stearyl ammonium nanoclay as a 1% w/w added amendment to a Nevada sand to determine the number of pore volumes required until the system reached breakthrough. The pre-modified nanoclay required the highest amount of water, 19 pore volumes, until breakthrough was reached. The fraction of nanoclay was increased to 2% w/w and breakthrough was not seen in the volume of water that was filtered through the system. The hydraulic conductivity for this nanoclay/sand mixture was 14 in/hr, greater than most minimum design values. Since the results so far indicated that this mixture would efficiently remove nitrate and still meet the minimum hydraulic conductivity, a synthetic stormwater solution was filtered through the column to test the nitrate removal when it is competing with other pollutant ions. This resulted in a projected breakthrough of 27 pore volumes and a 9 in/hr associated hydraulic conductivity. Future research can be completed to assess the best methodology to homogeneously mix the nanoclay particles with the sand to prevent leaching of the nanoclays. The next step in optimizing a bioretention cell for water quality treatment would be to focus research on how plants affect the system. If plants are able to remove nitrate from the system entirely, the lifetime of the bioretention cell could increase.
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Thompson, Geoffrey. "Best practice of crane support structures design : an expert survey." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1904.
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Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2007.Research on cranes and crane support structures has been completed at Stellenbosch University’s Structural Division. In order to link the research already completed with that which is practically relevant, an industry related expert survey was proposed. Consequently, the research title is “Best Practice of Crane Support Structures Design – An Expert Survey”. The primary objective of the study is to complete research, which can be used at a later stage to compile a “best practice” guideline for support structures design. The expert survey allows practical experience and opinion to be gathered from experts. The primary drawback being the uncertainty involved in such opinionated research material. For this reason an attempt is made in the thesis to apply a scientific approach, in order to attain rationally defendable results. The survey was conducted using interviews with experienced crane support structure designers and crane manufacturers in South Africa. The experts were then rated according to their answers to seeded questions, the number of colleague recommendations they each received and the years of experience each expert has. The expert opinion was subsequently combined using the expert ratings as weights. To further improve the scientific rationale behind the results, several of the topics mentioned by the experts were verified using related literature - thereby validating the use of the combined expert opinion for this research. The results obtained from the survey and verification process are regarded as useful to the objectives of the study. Information concerning pre-design specifications, loads and actions, structural analysis, design, design details and fatigue was compiled. The direct results are tabulated in an appendix and commentary, based on the expert opinions, is provided. A failure investigation was also completed with less success than initially intended. This was due, in part, to confidentiality issues and a lack of failure information easily accessible to the experts. For this reason the results of the failure investigation focuses more on various failure mechanisms. The success of the survey indicates that expert opinion is a useful tool for research. Furthermore, the minor differences in expert opinion, when compared to information obtained from crane support structure literature, indicates that the expertise in the South African crane support structure design is at an international standard.
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Bulman, Andrew. "Longbeach Mall : traffic impact assessment." Thesis, Stellenbosch : University of Stellenbosch, 2001. http://hdl.handle.net/10019.1/3427.
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Thesis (MEng (Civil Engineering))--University of Stellenbosch, 2001.This Traffic Impact Assessment (TIA) was commissioned in March 1998 as a supporting document to an application for the rezoning of an ert in Noordhoek from general housing to commercial use. The proposal at the time was to develop a medium·sized 15 000 m2 GLA shopping centre with supporting offices and a Health & Racquet Club. All the work (including managing the traffic counting team) was carried out by myself under the guidance of Dr Piet Jordaan at Gibb Africa Consulting Engineers. As financial backing and anchor tenants were secured for the development, the size of the proposed shopping centre was increased from a local facilily to a regional facilily of 31 000 m2 GFA to be developed in two phases. This necessitated a complete revision of the approach and content of the TIA. Owing to the regional nature of the new development, the TIA was expanded to include a wider geographical area of influence and a longer development period. This revised TIA was carried out by myself between September 1998 and March 1999 under the guidance of Dr Herman Joubert. Longbeach Mall opened for business in April 2001 complete with upgraded road network as recommended in the TIA The TIA is submitted as the final-year project for my Master's Degree in Traffic & Transportation Engineering. For the purposes of completion, an after·study of current traffic conditions on the local road infrastructure has also been included. The after·study was carried out in October 2001 (6 months after Longbeach Mall opened) and includes traffic counts at critical intersections during the Saturday morning peak period, observations of parking area utilisation, observations of shopping centre occupancy and discussions of the possible reasons for differences between predicted and actual traffic volumes. Confirmation that the study is original and was carried out by myself and permission from Arcus Gibb (Ply) Ltd to use the study as part of my final-year project, is provided in Appendix A.
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Sinske, A. N. (Alexander Nicholas). "Comparative evaluation of the model-centred and the application-centred design approach in civil engineering software." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52741.
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Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: In this dissertation the traditional model-centred (MC)design approach for the development of software in the civil engineering field is compared to a newly developed application-centred (AC)design approach. In the MC design software models play the central role. A software model maps part of the world, for example its visualization or analysis onto the memory space of the computer. Characteristic of the MC design is that the identifiers of objects are unique and persistent only within the name scope of a model, and that classes which define the objects are components of the model. In the AC design all objects of the engineering task are collected in an application. The identifiers of the objects are unique and persistent within the name scope of the application and classes are no longer components of a model, but components of the software platform. This means that an object can be a part of several models. It is investigated whether the demands on the information and communication in modern civil engineering processes can be satisfied using the MC design approach. The investigation is based on the evaluation of existing software for the analysis and design of a sewer reticulation system of realistic dimensions and complexity. Structural, quantitative, as well as engineering complexity criteria are used to evaluate the design. For the evaluation of the quantitative criteria, in addition to the actual Duration of Execution, a User Interaction Count, the Persistent Data Size, and a Basic Instruction Count based on a source code complexity analysis, are introduced. The analysis of the MCdesign shows that the solution of an engineering task requires several models. The interaction between the models proves to be complicated and inflexible due to the limitation of object identifier scope: The engineer is restricted to the concepts of the software developer, who must provide static bridges between models in the form of data files or software transformers. The concept of the ACdesign approach is then presented and implemented in a new software application written in Java. This application is also extended for the distributed computing scenario. Newbasic classes are defined to manage the static and dynamic behaviour of objects, and to ensure the consistent and persistent state of objects in the application. The same structural and quantitative analyses are performed using the same test data sets as for the MCapplication. It is shown that the AC design approach is superior to the MC design approach with respect to structural, quantitative and engineering complexity .criteria. With respect to the design structure the limitation of object identifier scope, and thus the requirement for bridges between models, falls away, which is in particular of value for the distributed computing scenario. Although the new object management routines introduce an overhead in the duration of execution for the AC design compared to a hypothetical MC design with only one model and no software bridges, the advantages of the design structure outweigh this potential disadvantage.
AFRIKAANSE OPSOMMING: In hierdie proefskrif word die tradisionele modelgesentreerde (MC)ontwerpbenadering vir die ontwikkeling van sagteware vir die siviele ingenieursveld vergelyk met 'n nuut ontwikkelde applikasiegesentreerde (AC) ontwerpbenadering. In die MContwerp speel sagtewaremodelle 'n sentrale rol. 'n Sagtewaremodel beeld 'n deel van die wêreld, byvoorbeeld die visualisering of analise op die geheueruimte van die rekenaar af. Eienskappe van die MContwerp is dat die identifiseerders van objekte slegs binne die naamruimte van 'n model uniek en persistent is, en dat klasse wat die objekte definieer komponente van die model is. In die AC ontwerp is alle objekte van die ingenieurstaak saamgevat in 'n applikasie. Die identifisieerders van die objekte is uniek en persistent binne die naamruimte van die applikasie en klasse is nie meer komponente van die model nie, maar komponente van die sagtewareplatform. Dit beteken dat 'n objek deel van 'n aantal modelle kan vorm. Dit word ondersoek of daar by die MC ontwerpbenadering aan die vereistes wat by moderne siviele ingenieursprosesse ten opsigte van inligting en kommunikasie gestel word, voldoen kan word. Die ondersoek is gebaseer op die evaluering van bestaande sagteware vir die analise en ontwerp van 'n rioolversamelingstelsel met realistiese dimensies en kompleksiteit. Strukturele, kwantitatiewe, sowel as ingenieurskompleksiteitskriteria word gebruik om die ontwerp te evalueer. Vir die evaluering van die kwantitatiewe kriteria word addisioneel tot die uitvoerduurte 'n gebruikersinteraksie-telling, die persistente datagrootte, en 'n basiese instruksietelling gebaseer op 'n bronkode kompleksiteitsanalise , ingevoer. Die analise van die MC ontwerp toon dat die oplossing van ingenieurstake 'n aantal modelle benodig. Die interaksie tussen die modelle bewys dat dit kompleks en onbuigsaam is, as gevolg van die beperking op objekidentifiseerderruimte: Die ingenieur is beperk tot die konsepte van die sagteware ontwikkelaar wat statiese brue tussen modelle in die vorm van lêers of sagteware transformators moet verskaf. Die AC ontwerpbenadering word dan voorgestel en geïmplementeer in 'n nuwe sagteware-applikasie, geskryf in Java. Die applikasie word ook uitgebrei vir die verdeelde bewerking in die rekenaarnetwerk. Nuwe basisklasse word gedefinieer om die statiese en dinamiese gedrag van objekte te bestuur, en om die konsistente en persistente status van objekte in die applikasie te verseker. Dieselfde strukturele en kwantitatiewe analises word uitgevoer met dieselfde toetsdatastelle soos vir die MC ontwerp. Daar word getoon dat die AC ontwerpbenadering die MC ontwerpbenadering oortref met betrekking tot die strukturele, kwantitatiewe en ingenieurskompleksiteitskriteria. Met betrekking tot die ontwerpstruktuur val die beperking van die objek-identfiseerderruimte en dus die vereiste van brue tussen modelle weg, wat besonder voordelig is vir die verdeelde bewerking in die rekenaarnetwerk. Alhoewel die nuwe objekbestuurroetines in die AC ontwerp in vergelyking met 'n hipotetiese MC ontwerp, wat slegs een model en geen sagteware brue bevat, langer uitvoerduurtes tot gevolg het, is die voordele van die ontwerpstruktuur groter as die potensiële nadele.
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Carmona, David Isaac. "Quantifying the Life Cycle Benefits of Performance-Based Design in Sustainable Design." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/708.
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ABSTRACT
Quantifying the Life Cycle Benefits of Performance-Based Design in Sustainable Design
David Carmona
For this thesis, a method is developed and tested for use with performance based design to quantify the sustainable and financial benefits of designing buildings to a structural performance level higher than Life-Safety. This paper starts to answer the question, “which would be a better investment: build structures to a performance level of Immediate Occupancy (IO) with the likelihood of less damage and downtime after an earthquake or continue to build to the building code’s implied minimum performance level of Life-Safety (LS)?”
An ASCE 7-05 designed base model building (six-story, steel moment frame, office located in San Francisco) was designed to meet the minimum requirements of the LS or stricter code requirements of the IO performance objectives, respectively. Performance levels were verified using the ASCE 41-06 linear static procedures and ETABS models.
The overall cost and cost difference for building the two structures were determined using RSMeans reference manuals. The structural upgrade cost from LS to IO is roughly 1.6% of the $33.4 million initial building cost for a total of approximately $500,000.
The financial damage caused to the two buildings due to a series of earthquakes was determined using the ATC-58 Guidelines and the modeling capabilities of its companion software Performance Assessment and Calculation Tool (PACT). Due to PACT’s work-in-progress status and limited quantity of fragility curves representing building components, results are questionable and expected to become more fine-tuned as the software develops and there is an increased availability of fragility curves.
Using the PACT program, the difference in annualized loss between the IO and LS buildings was determined to be roughly $40,000. This is equivalent to a 2009 present cost of $590,000 over a 50-year building lifespan. By designing the building to an IO performance level, the owner potentially saves 18% ($590,000 loss to future seismic damages/ $500,000 cost to upgrade) over the life-span of the building. As buildings begin to incorporate state-of-the-art, more expensive and efficient components, designing higher performing structures to protect these upfront costs will prove more beneficial than repairing the components at a future date. Considering building downtime and loss of life would increase the value of savings and provide an additional incentive to design a structure directly to a higher performance level.
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Swain, Allyson. "Modeling the Groundwater Basin in the Northern Cities Management Area." DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2330.
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A model was developed to simulate the groundwater of 8,300 acres of the Northern Cities Management Area (NCMA), which encompasses the northern portion of the Arroyo Grande Watershed and a small subset of the Santa Maria Valley Groundwater Basin. This watershed and groundwater basin is located on the coast and contains Oceano and the Cities of Arroyo Grande, Grover Beach, Pismo Beach. Groundwater in the NCMA is used heavily for agricultural irrigation in the southern portion and municipal applications in the northern portion. Up to 18 of these municipal wells and over 50 irrigation wells are drawing groundwater at any time. Due to the critical nature of both uses, and location on the coastline, both supply and quality is a significant concern. The objective of this research was to improve an existing groundwater model with a longer model duration, a more detailed and discretized recharge estimation, and incorporation of addition municipal well data. Some data was preprocessed in ArcMap. Groundwater modeling was accomplished with Aquaveo GMS using MODFLOW-NWT upstream weighting package (UPW). Elevation, hydrologic soil conditions, stream gauge heights and flows, recharge rates, fault locations, well locations and pumping rates, and transient head boundaries were created via coverages in GMS and mapped to MODFLOW. The model was calibrated using Parameter Estimation (PEST) with Singular Value Decomposition-Assist (SVD-Assist) to observation data in six select monitoring wells and fifteen Sentry wells. The model showed outflow from the domain to the ocean with groundwater flows shifting to parallel the coast following dry periods and significant simulated drawdown from one particular municipal well. These trends can provide water purveyors in the area with additional information on groundwater trends and effects of pumping rates on formation drawdown.
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Chirwa, M. P. W. "An evaluation of the minimum requirements for the design of rural water supply projects." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2895.
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Thesis (MScEng (Civil engineering))--University of Stellenbosch, 2005.In this study, the minimum standards required for the design of rural piped water supply projects as set by the Department of Water Affairs and Forestry (DWAF) are evaluated with respect to capital pipe cost using the Nooightgedacht rural water supply scheme selected as a case study.
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Barnard, M. M. "Discharge measurement at natural controls in Western Cape rivers." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53395.
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Thesis (MEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This study sets out to explore the possibilities and accuracy of flow measurement at natural controls, focussing specifically on Western Cape cobble-bed rivers. These rivers are regarded as being difficult in terms of flow measurement, mostly due to their large scale roughness and very turbulent and uneven flows. The aim is to determine a system through which various types of natural controls can be calibrated, by establishing a relationship between the discharge coefficient and the physical characteristics of each control type. This was achieved by conducting an extensive field investigation, focussing on the identification and gauging of both critical and uniform natural controls. Two types of critical controls were identified and investigated, namely step-pool controls and horizontal constriction controls as well as one type of uniform flow control, namely the plane bed control. Step-pool controls were found to be very robust controls which provided efficient critical controls for a wide range of flows. Horizontal constriction controls proved to be reasonably accurate measurement sites and, because of their physical characteristics, they are able to measure the full range of flows from low to flood flows. Uniform controls are widely used for flow measurements on deep rivers, but such measurements become highly unreliable when flow depths are small and bed roughness high as is the case with cobble-bed rivers. Under conditions of high roughness, generally speaking critical controls can be calibrated more accurately than uniform controls and are therefore to be preferred. The field study was followed by a series of laboratory tests, focussing on horizontal constriction controls. Calibration equations were derived by which the discharge coefficient value can be determined for a given constriction ratio and upstream energy head. Results from both the fieldwork and laboratory work were analysed and integrated to determine a calibration system applicable to natural controls in Western Cape cobbleand boulder-bed rivers. Reasonably accurate values of the discharge coefficients for different types of natural controls were established, which should be widely applicable. Additionally, guidelines were drawn up for the measurement of flow at natural controls, to be used by both engineers and non-engineers. Discharge measurement at natural controls in the Western Cape was found to be a viable and reasonably accurate way of determining river discharge. It proves to be an environmentally acceptable way of measurement, using the natural river characteristics rather than seriously interfering with them or damaging them. These advantages make discharge measurement at natural controls a promising means of determining river discharge in the future.
AFRIKAANSE OPSOMMING: Die beste posisie vir vloeirneting in riviere is waar die topografie van die rivier 'n unieke verhouding tussen die deurstroming en die water diepte bewerkstellig. Hierdie studie ondersoek die uitvoerbaarheid en akkuraatheid van vloeirneting by natuurlike kontroles met die fokus op Wes-Kaapse spoelklip riviere. Vloeirneting in spoelklip riviere word as baie ingewikkeld beskou weens die grootte van die bedpartikels relatieftot die vloeidiepte en gevolglike onewe, turbulente vloeie. Die doel van die studie was om 'n stelsel te ontwikkel waardeur verskillende tipes natuurlike kontroles gekalibreer kan word deur verwantskappe te bepaal tussen die deurstromings koëffisiënt en die stroom-op energie hoogte. Bogenoemde is bepaal met behulp van 'n uitgebreide veldstudie waarin die hoof tipes natuurlike kontroles, nl. die kritiese vloei kontrole en die uniforme vloei kontrole, geidentifiseer en gekalibreer is. Twee tipes kritiese vloei kontroles is ondersoek, naamlik die trap-poel ("step-pool") kontrole en die horisontale vernouing kontrole. Daar is bevind dat beide die trap-poel kontrole en die horisontale vernouing baie effektiewe kritiese kontroles is, waarmee 'n wye reeks van vloeie gemeet kan word. Uniforme vloei kontroles word algemeen vir vloeimeting in diep vloeiende riviere gebruik, maar sulke metings word hoogs onbetroubaar wanner die vloeidiepte klein is relatief tot die partikel grootte van die rivierbed, soos in die geval van spoelklip riviere. Onder hierdie omstandighede kan kritiese kontroles in die algemeen meer akkuraat gekalibreer word en word hul gevolglik bo uniforme vloei kontroles verkies. Die veldstudie is gevolg deur 'n reeks laboratorium toetse, wat fokus op die horisontale vernouing kontrole. Kalibrasie vergelykings is afgelei waarmee die deurstromings koëffisient vir 'n gegewe stroom-op energiehoogte en vernouings-verhouding bereken kan word. Resultate van beide die veldstudie en die laboratorium toetse is geanaliseer en geïntegreer om 'n kalibrasie stelsel te bepaal wat van toepassing is op natuurlike kontroles in Wes-Kaapse spoelklip riviere. Aanvaarbare waardes vir die deurstromings koëffisiente vir verskeie tipes natuurlike kontroles is bepaal, wat algemeen toepasbaar behoort te wees. Riglyne vir die meting van riviervloei by natuurlike kontroles is opgestel vir die gebruik deur beide ingenieurs en nie-ingenieurs. Vloeimeting deur middel van natuurlike kontroles is 'n lewensvatbare metingsmetode waarmee riviervloei redelik akkuraat bepaal kan word. Dit is 'n omgewingsaanvaarbare metings metode wat die natuurlike karakter van die rivier gebruik, eerder as om ernstig daarmee in te meng of dit te beskadig. Hierde positiewe eienskappe maak vloeimeting deur middel van natuurlike kontroles 'n belowende metingsmetode vir die toekoms.
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De, Lange Johan Hendrik. "An experimental investigation into the behaviour of a 5 ton electric overhead travelling crane and its supporting structure." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/414.
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Alberti, L. I. "Flow around cylindrical towers : the stabalising role of vertical ribs." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2426.
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Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2006.The aim of this thesis is to study the stabilising effect which vertical ribs may have on a tall cylindrical structure, with the focus on the proposed Solar Chimney. The report begins with a brief introduction to the Solar Chimney concept. A study is made of flow regimes which exist for flow around a circular cylinder and these flow regimes, together with their characteristics, are described. Various threats to the Solar Chimney are identified and will be investigated. The natural shape and strength of the Saguaro Cactus leads to the investigation of vertically ribbed cylinders. Experimental wind tunnel tests are performed in Tokyo, Japan to obtain external pressure distributions. A smooth cylindrical model, as well as two different configurations of vertically ribbed cylinders are tested. These external pressure distributions are numerically integrated in order to obtain calculated drag coefficient values for the cylinders. The drag coefficients for a smooth cylinder and cylinders with vertical ribs are obtained experimentally by means of total drag force measurements. These tests were performed in the wind tunnel at the University of Stellenbosch. The effect of aspect ratio of a smooth cylinder is also addressed. Computational Fluid Dynamics (CFD) analyses are carried out using the CFD software program, FLUENT. Both the drag coefficient and the external pressure distributions were investigated in this way. The differences between theoretical conditions and those of real life conditions of a smooth cylinder are discussed. The report ends by concluding the stabilising effect of vertical ribs on tall cylindrical structures and how these ribs may eliminate some of the present threats to the proposed Solar Chimney.
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De, Villiers J. W. L. "2D Modelling of turbulant transport of cohesive sediments in shallow reservoirs." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2940.
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Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2006.Modelling of the transport of fine cohesive sediments, as found in most South African reservoirs, has not been well developed. This is because the transport processes that are involved are complex and the theories not as implicit as the traditional equilibrium transport theories for coarse non-cohesive sediment. Advection and dispersion are found to be the processes that best describe the transport of fine sediments in turbulent flow conditions. A two-dimensional modelling tool, MIKE 21C, which simulates reservoir hydrodynamics and cohesive sediment transport processes with an advection-dispersion model, was evaluated in this thesis. The creation of such a numerical model involves the setting up of a suitable curvilinear grid and requires data on the bathymetry, recorded inflows as well as water levels. It also requires sediment characteristic parameters and transport parameters. These parameters have to be specified by the user based on previous studies and field measurement data. MIKE 21C was applied to laboratory flume tests and reservoir case studies in the field in order to determine the effects that these parameters have on the sediment transport in a series of sensitivity studies. Ranges were determined within which these parameter values should fall. A procedure was also developed through which reservoir sedimentation models can be calibrated.
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Brand, W. W. (Willem Wouter). "Reliability assessment of a prestressed concrete member." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52430.
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Thesis (MScEng)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: First-order second-moment structural reliability methods are used to assess the reliability of a prestressed concrete beam. This beam was designed for imposed office floor loads and partitions following the limit states design method as provided for by the applicable South African structural codes, viz SABS 0100-1:1992 and SABS 0160:1989. The reliability is examined at two limit states. At the ultimate limit state of flexure the ultimate moment of resistance must exceed the applied external moment at the critical section, while at the serviceability limit state of deflection the deflection must satisfy the codespecified deflection criteria. Realistic theoretical models are selected to express the flexural strength and deflection of the prestressed concrete member, while appropriate probabilistic models are gathered from the literature for loading, resistance and modelling uncertainties. The calculated reliability index at the ultimate limit state of flexure (3.10) is lower than expected in view of the fact that this represents a non-critical limit state in the case of a Class 2 prestressed concrete member. This condition can be explained with reference to the relatively high uncertainty associated with the modelling error for flexural strength. The calculated reliability index at the serviceability limit state of deflection (l.67) compares well with acceptable practice. The study further focuses on the sensitivity of the reliability at the two limit states of interest to uncertainty in the various design parameters. The ultimate limit state of flexure is dominated by the uncertainty associated with the modelling error for flexural strength, while the contribution to the overall uncertainty of the ultimate strength and area of the prestressing steel and the effective depth is less significant. In comparison the reliability at the serviceability limit state of deflection is not dominated by the uncertainty associated with a single basic variable. Instead, the uncertainty associated with the modelling error, creep factor and prestress loss factor are all significant. It was also demonstrated that the variability in beam stiffness is not a major source of uncertainty in the case of a Class 2 prestressed concrete member. It is recommended that the present code provisions for ultimate strength and deflection should be reviewed to formulate theoretical models with reduced systematic and random errors. The effect of the uncertainty associated with the creep and prestressed loss factors should also be adressed by adjustment of the partial material factor for concrete at the serviceability limit state of deflection. Furthermore, research must be directed towards formulating an objective failure criterion for deflection. The uncertainty in the deflection limit must therefore be quantified with a probability distribution.
AFRIKAANSE OPSOMMING: Eerste-orde tweede-moment struktuur betroubaarheid metodes word ingespan om die betroubaarheid van 'n voorspanbeton balk te bereken. Hierdie balk is ontwerp vir opgelegte kantoor vloerbelasting en partisies volgens die grenstoestand ontwerp metode soos beskryf in die toepaslike Suid-Afrikaanse boukodes, naamlik SABS 0100-1: 1992 en SABS 0160: 1989. Die betroubaarheid word ondersoek by twee grenstoestande. By die swiglimiet van buiging moet die weerstandsmoment die eksterne aangewende moment oorskrei by die kritieke balksnit, terwyl die defleksie die kriteria soos voorgeskryf deur die kode moet bevredig by die dienslimiet van defleksie. Realistiese teoretiese modelle word gebruik om die buigsterkte en defleksie van die voorspanbeton balk te bereken. Verder is geskikte waarskynlikheid modelle uit die literatuur versamelom die belasting, weerstand en modelonsekerhede te karakteriseer. Die betroubaarheid indeks soos bereken vir die swiglimiet van buiging (3.10) is laer as wat verwag sou word in die lig van die feit dat hierdie nie 'n kritieke grenstoestand verteenwoordig in die geval van 'n Klas 2 voorspan element nie. Dit kan verklaar word met verwysing na die relatiewe groot onsekerheid wat geassosieer word met die modellering fout vir buigsterkte. Die berekende betroubaarheid indeks vir die dienslimiet van defleksie (1.67) vergelyk goed met aanvaarde praktyk. Die studie fokus verder op die sensitiwiteit van die betroubaarheid by die twee grenstoestande onder beskouing ten opsigte van die onsekerheid in die verskillende ontwerp parameters. By die swiglimiet van buiging word die onsekerheid oorheers deur die bydrae van die modelering fout vir buigsterkte. Die bydraes tot die totale onsekerheid deur die swigsterkte en area van die voorspanstaal sowel as die effektiewe diepte is minder belangrik. By die dienslimiet van defleksie word die betroubaarheid nie oorheers deur die onsekerheid van 'n enkele basiese veranderlike nie. In stede hiervan is die onsekerheid van die modellerings fout, kruipfaktor en voorspan verliesfaktor almal noemenswaardig. Daar word verder aangetoon dat die veranderlikheid in balkstyfheid nie 'n belangrike bron van onsekerheid in die geval van 'n Klas 2 voorspan element is nie. Daar word aanbeveel dat die bestaande voorskrifte in die kode vir buigsterkte en defleksie aangespreek moet word deur teoretiese modelle met klein modelonsekerhede te formuleer. Die uitwerking van die onsekerheid van die kruip- en voorspan verliesfaktore kan aangespreek word deur 'n aanpassing te maak in die parsiële materiaalfaktor vir beton in die geval van die dienslimiet van defleksie. Navorsing moet verder daarop gemik wees om 'n objektiewe falingskriterium vir defleksie te formuleer. Die onsekerheid van die toelaatbare defleksie moet dus gekwatifiseer word deur 'n waarskynlikheidsverdeling.
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Vosloo, Robert Nicolaas. "The role of civil engineering professionals within the housing environment in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20146.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The development of mass housing is an excellent example of multi-disciplinary projects. Several housing projects have been unsuccessful due to a misunderstanding of the necessary collaboration and buy-in that are required from all parties concerned. The focus of this study is to identify the required skill sets and responsibilities of the Housing Project Manager in the Housing environment, and in turn, will support the development of the foundation of the civil engineering postgraduate curricula. Civil engineers are educated with a strong focus on technical subjects, but not much attention is paid to many of the less technical aspects as found in housing projects. Furthermore, the multi-disciplinary aspects of large projects do not receive sufficient attention in either the undergraduate or postgraduate curricula. Considering that many civil engineers become actively involved as managers of housing projects, this paper will present an investigation into the requirements of the curricula of a postgraduate qualification for civil engineers towards becoming managers in housing projects. The investigation will include aspects of multi-disciplinary coordination, the less technical aspects of housing development, but will not exclude a comprehension of technical involvement. In order to identify these skill sets and responsibilities several approaches were adopted. The approaches adopted in this dissertation include: (i) a comprehensive literature study regarding the housing environment and the position of the housing project manager, (ii) a review of several housing case studies with project management related problems, (iii) consulting with several housing management professionals from different sectors in the housing industry, and (iv) a review of existing formulations of the role and responsibilities of the housing project manager. The findings from this study provide evidence that civil engineers operating in the housing environment as project managers require additional education, due to the multi-disciplinary nature of housing projects. The main conclusion drawn from this study is that educating civil engineers towards the management of housing projects would contribute significantly to the housing environment through increasing productivity and quality, and can contribute to meet the housing targets of the government.
AFRIKAANSE OPSOMMING: Die ontwikkeling van massa behuising is 'n uitstekende voorbeeld van multidissiplinêre projekte. Verskeie behuisingsprojekte was al onsuksesvol as gevolg van 'n misverstand oor die nodige samewerking en bydraes wat vereis word van alle betrokke partye. Die fokus van hierdie studie is om die vaardighede en verantwoordelikhede van die behuisingsprojekbestuurder in die behuisingsomgewing te identifiseer. Hierdie kennis ondersteun die ontwikkeling van ʼn raamwerk vir ʼn nagraadse kurrikulum in behuisingsbestuur. Siviele ingenieurs is opgelei met 'n sterk fokus op tegniese vaardighede, maar relatief min aandag word geskenk aan minder tegniese aspekte soos gevind word in behuisingsprojekte. Verder, multidissiplinêre bestuursaspekte van groot projekte ontvang nie voldoende aandag in óf die voorgraadse óf nagraadse kurrikula nie. Wetende dat baie siviele ingenieurs aktief betrokke raak as bestuurders van behuisingsprojekte, ondersoek hierdie studie ʼn raamwerk vir ʼn nagraadse kwalifikasie vir siviele ingenieurs as bestuurders van behuisingsprojekte. Die ondersoek sluit in aspekte van die multidissiplinêre koördinasie asook minder tegniese aspekte van behuisingsontwikkeling, maar dit sluit nie 'n begrip van die tegniese betrokkenheid uit nie. Verskeie benaderings is toegepas om die vaardighede en verantwoordelikhede van behuisingsbestuurders te identifiseer. Die benaderings sluit in: (i) 'n omvattende literatuurstudie ten opsigte van behuising en die posisie van die behuisings-projekbestuurder, (ii) 'n oorsig van verskeie behuisings- gevallestudies met projekbestuur verwante probleme, (iii) raadpleging met verskeie professionele rolspelers van verskillende sektore in die behuisingbestuur omgewing, en (iv) 'n hersiening van bestaande beskrywings van die rol en verantwoordelikhede van die behuisings-projekbestuurder. Die bevindinge van hierdie studie verskaf bewyse dat siviele ingenieurs wat in die behuisingsbedryf as projekbestuurders optree, bykomende opleiding benodig as gevolg van die multidissiplinêre aard van projekte. Die belangrikste gevolgtrekking van hierdie studie is dat die opleiding van siviele ingenieurs in die bestuur van behuisingsprojekte ʼn aansienlike bydrae kan lewer tot behuising deur produktiwiteit en kwaliteit te verhoog. Dit kan bydra tot die bereiking van die regering se behuisingsdoelwitte.
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Chan, Ada Mingwah. "Investigation of Dairy Wastewater Using Biowish." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1325.
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Various bacterial products from BiOWiSHTM Technologies have been tested in dairy wastewater experiments to determine the bacterial mixes’ ability for enhanced degradation of biochemical oxygen demand (BOD), solids, and nitrate concentrations. The dairy wastewater was augmented with various bacterial composition obtained from BiOWiSHTM. The bacterial mixes experimented were US Aqua, Thai Aqua, BMT, Osprey, Fruit Wash, KLB, LCM1, and MDG. Method development was a crucial process to optimize and test the effects of the BiOWiSHTM Technologies bacterial mixes.
After 5 experiments, the BOD tests showed that for some of the tests, the redosage of bacteria helped further drive the BOD concentrations to be lower than the control. With redose, the samples reduced BOD by 10 – 55% to samples that were not redosed. Although the redose adds supplemental BOD initially, the addition showed that in some cases, the bacterial sample BOD is lower than without any redose.
For the solids testing, different solids tests showed either conclusive impacts of bioaugmentation or no effect. For the total solids (TS) and total suspended solids (TSS) tests, both showed about a 10% decrease or increase in solids throughout the experiments. The smaller solids components, volatile suspended solids (VSS), did demonstrate that the bacterial mixes reduced organic suspended solids more than the control. The bioaugmented samples reduced the VSS organic material by 5 – 15% compared to the control with BiOWiSHTM.
Particle size distribution (PSD) tests provided a breakdown of which particle sizes were increasing and decreasing. Those samples bioaugmented with BiOWiSHTM showed that smaller particles (0.7 µm pore size) were getting assimilated by the bacteria which produced more bacteria (larger pore sizes of 5 µm). After the bacteria ran out of food, the sequentially smaller pore size (2.5 µm) increased while the smaller pore sizes (1.6 µm and 0.7 µm) remained low. The rate limiting step was determined to be 1.6 – 2.5 µm where the control’s zero rate constant was +1.4 mg/L-day whereas the USA and TA was -1.1 mg/L-day and -1.4 mg/L-day respectively. Thus, the BiOWiSHTM samples decreased TSS in smaller pore size filters by about 10 – 20% more than the control.
Ion chromatography (IC) measured that nitrate levels were clearly reduced by 30 – 50% adding the BiOWiSHTM bacteria compared to the control. Therefore, the additional bacteria further denitrified the nitrate (NO3-) than if no BiOWiSHTM was added. Denitrification experiments were performed for pure Bacillus spores, KLB, that showed a 90% decrease of NO3- to the control.
Keywords: bioaugmentation, BiOWiSHTM, BOD, dairy wastewater, dissolved solids, ion chromatography, nitrate, particle size distribution, redose, suspended solids, total solids, volatile suspended solids
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Heimel, Daniel Eric. "Anaerobic Co-digestion of Wastewater Treatment Pond Algae with Wastewater Sludge." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/440.
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Microalgae harvested from wastewater treatment ponds can be anaerobically digested to produce biogas, a renewable fuel resource. However, past experiments have shown some limitations of algae digestion. Algal cell walls are thought to be resistant to digestion, and the high protein content of algae can lead to ammonia toxicity in digesters. Co-digestion of algae with substrates containing higher C:N ratios (e.g., waste paper) can be used to maintain non-inhibitory ammonia concentrations and increase methane production. However, high carbon waste co-substrates have become costly or are not readily available in many communities. Although domestic wastewater sludge has only a marginally higher C:N ratio than algae biomass, sludge is a practical co-substrate for treatment pond facilities using primary sedimentation. The present laboratory research evaluated the use of wastewater sludge as a co-substrate with treatment pond algae that were harvested by coagulation and dissolved air flotation. The research was meant to assist in the planning for full-scale algae digestion at a large pond facility in California. The independent variables evaluated were algae/sludge ratio in the digester feed (100% to 0%), organic loading rate (OLR; 2 or 4 g volatile solids/L-d), and hydraulic residence time (HRT; 20 or 40 d), while the main dependent variables were methane yield, volumetric methane production, and the dewaterability of the digester effluents. Co-digestion of algae with sludge was stable, with healthy pH, at all algae/sludge ratios with OLRs up to 4 g volatile solids loaded per liter digester per day (g VS/L-d) at a 20-d HRT. For digesters fed algae biomass exclusively, at a 2 g VS/L-d OLR and a 20-d HRT, the methane yield was 0.26 L/g VS-d and methane productivity was 0.52 g VS/L digester-d. A control digester fed sludge exclusively, with the same loading rate, produced more methane: the yield was 0.44 L/g VS-d and production was 0.87 L/L-d. No significant synergistic benefit in algae methane yield was observed due to co-digestion with wastewater sludge. The effluent from digesters fed only algae dewatered as effectively or better than digesters fed only wastewater sludge. However, freezing of the algae biomass prior to digestion could have affected the results. An engineering model was developed to estimate heating requirements and net electricity production for full-scale algae digesters. For two example climates (Mediterranean and continental desert), the model predicted that despite the lower methane production of algae digestion, heat recovered from cogeneration and electricity generation would be more than sufficient to fulfill the inputs required for algae digestion. For facultative pond wastewater treatment facilities with existing collection and digestion of primary sludge, addition of the algae produced to the digesters is expected to increase electricity production by 120%.
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Limpert, Alexandra D. "Field Emissions of Methane and Nitrous Oxide from California Landfills." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2027.
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Comprehensive and systematic aerial and field investigations were conducted at representative California landfills to quantify emissions of methane and nitrous oxide. Landfills are highly engineered; however, they are one of the largest anthropogenic sources of greenhouse gases, causing human health and safety concerns. Methane (CH4) and nitrous oxide (N2O) are significant greenhouse gases with high global warming potentials that are generated in a landfill environment.
For site selection, sites were evaluated based on waste in place, climate zone, faults and oil and gas operations, population density, cover conditions and percentage of cover types, age of waste, waste profile, landfill style and configuration, and disposal of waste tires. Fifteen representative sites were chosen for the aerial portion of testing, and of those fifteen, five sites were selected for extensive ground testing using the static flux chamber method, conducted over a year-long time period. At the five sites for ground testing, between five and seven cover systems were tested at each site during the wet and dry season. Daily, intermediate, and final covers were tested to obtain representative and comparative measurements during the wet and dry season to account for seasonal variation. In addition to the flux chamber testing, geotechnical characterization of cover materials was conducted.
CH4 flux values exhibited higher variability in the dry season (102 g/m2/d to -101 g/m2/d) than the wet season (102 g/m2/d to 10-1 g/m2/d). N2O flux values exhibited slightly higher variability in the wet season (10-1 g/m2/d to -10-3 g/m2/d) than the dry season (10-1 g/m2/d to -10-3 g/m2/d). The measured flux value for CH4 was generally greater than the measured flux value for N2O across both seasons. N2O flux values (10-1 g/m2/d to -10-3 g/m2/d) exhibited less variability than CH4 flux values (102 g/m2/d to -10-1 g/m2/d). Relationships were developed between aerial emissions and areal coverage, throughput, waste column height, and waste in place. All correlations were positive. Relationships were also developed between flux values and geotechnical properties of covers, including density and cover thickness. Most geotechnical parameters yielded limited correlation.
The surface flux values from the field investigation were scaled up to estimate facility-wide surface emission values. The methane surface emissions ranged from 10-1 to 103 and from 100 to 102 tonnes/year in the wet season and dry season. The nitrous oxide surface emissions ranged -10-2 to 100 and from 10-2 to 10-1 tonnes/year in the wet season and dry season, respectively. Emissions were converted to CO2 equivalent (CO2 E) to allow for comparison between methane and nitrous oxide. The methane surface emissions in CO2 E terms ranged from 101 to 104 tonnes/year in both the wet season and dry season, respectively. The nitrous oxide surface emissions in CO2 E terms ranged from -100 to 102 and from 101 to 102 tonnes/year in the wet season and dry season, respectively. Aerial and ground emissions were compared, with aerial results being higher at all five ground sites. This study provides systematic and comprehensive field emissions testing comparing climate and waste in place, among other parameters, that demonstrate the complicated nature of the landfill environment.
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Bowen, Christian A. "Effects of Raceway Pond Water and Nutrient Recycling on Microalgae Production and Harvesting." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1896.
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To be environmentally sustainable, algae biofuel production requires extensive recycling of water and nutrients during algae cultivation. Such recycling can be in the form of reuse of external wastewaters, such as from municipal sewers, but, to achieve significant biofuels production, internal recycling at the algae farms is also needed. A potential difficulty with internal recycling is the accumulation of auto-inhibitory compounds in recycled algae pond water. An additional concern is that nutrients in the residuals from algae biofuel manufacturing will be only partly bioavailable. Both these factors can limit the extent of internal recycling. Ultimately, combining external and internal recycling might be the most sustainable as long as these limiting factors are not excessive. Another important consideration in algae biofuel feedstock production is harvesting, which can be energy intensive and expensive. Bioflocculation of algae cells followed by sedimentation is a low input harvesting method, but one that might be affected by resource recycling. In the present 7-month study, algae productivity and settleability were measured for several types of water and nutrient recycling, using pilot raceways and tubes settler tanks fed municipal wastewater.
Two control raceway sets and two types of water and nutrient recycling raceway sets were operated concurrently. Each set was comprised of duplicate raceways (33-m2 surface area each, 0.3-m deep, 4-day hydraulic residence time with CO2 supplementation). One control set was fed primary clarifier effluent while the other control set was fed nitrified, filtered reclaimed wastewater. The two experimental raceway sets were fed different nutrients. One set received anaerobically-digested algal biomass (algae digestate) and the other set chemical fertilizer. Both recycling raceway sets were monitored to determine if water and nutrient recycling had any detrimental impacts on algal biomass growth.
Productivity was reported as gross and net in terms of volatile suspended solids (VSS). Gross productivity was based on raceway effluent biomass flow, which could be harvested for biofuel production. Net productivity was based on influent minus effluent biomass flows, which better represents algae growth. As a complement to the productivity data, measurements were made of indictors (salt, soluble chemical oxygen demand, and soluble UV absorbance) of potentially inhibitory substances and of nitrogen and phosphorus concentrations, which would have limited growth if they were too low.
After 7 months of continuous operation and 50 cycles of water reuse, the algae productivities of the water and nutrient recycling raceways matched or exceeded the productivities of the control raceways. Net productivities of the primary effluent-fed and reclaimed water-fed control ponds averaged 15.4 and 18.0 g-VSS/m2-day, respectively, while the digestate-fed and fertilizer-fed recycling ponds net productivities averaged 19.6 and 18.8 g-VSS/m2-day, respectively. The average standard deviation of the various duplicate sets ranged from 0.3 – 4.0 g-VSS/m2-day. These results do not indicate that algae were inhibited during the 7 months of continuous water recycling and digestate fertilization. In fact, the results suggest that recycling enhances productivity, although the statistical power of this experiment was low.
Indicators of potentially inhibitory substances were monitored during the experiment (salinity, soluble chemical oxygen demand, and UV absorbance). Only salt concentrations showed significant accumulation in the ponds, but not to concentrations expected to be inhibitory. A greater number of replicates and a longer experimental period are recommended in future experiments.
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Ward, Courtney E. "ASSESSING NEAR-FIELD OUTDOOR CONCENTRATION VARIABILITY FROM RESIDENTIAL WOOD SMOKE COMBUSTION SOURCES." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/122.
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ABSTRACT Assessing Near-Field Outdoor Concentration Variability from Residential Wood Smoke Combustion Sources Courtney Ward The primary goal of this research was to determine whether near field effects from residential wood smoke emissions have a significant impact on acute and/or average PM2.5 concentrations, and therefore health risks. To this end, three primary research objectives were addressed: (1) measurement of the variability of wood smoke concentrations within a residential neighborhood with wood smoke sources, (2) establishment of whether the magnitude of near-source contributions to exposures can be estimated using typically available data, and (3) prediction of wood smoke concentrations using linear regression techniques on meteorological parameters.
This project was divided into 4 primary tasks. Neighborhood Selection (Task 1), Detailed Sample Plan and Method Validation (Task 2), Field Study to deploy equipment and personnel to the study area (Task 3), and Data Analysis (Task 4). The data analysis was divided into three sections: (1) evaluation of aethalometer black carbon (BC) variability, (2) regression and correlation analyses between meteorological factors and aethalometer BC, and (3) evaluation of the Personal Environmental Monitor (PEM) BC variability.
BC concentrations, as measured by aethalometers, showed that near-source contributions to average concentrations varied widely within the 1 km2 study area, with measured BC differences up to 3.27 &#;g/m3 which corresponds to an estimated PM2.5 concentration ranging from 54.5 to 81.75 &#;g/m3. Consequently, BC concentrations, and therefore exposures, are dependent upon the location within a residential area and cannot be estimated well using measurements from a single location. Based on the results from this study, it is recommended that the standard method of measuring PM2.5 should be updated by either placing additional monitors throughout the region or estimating the variation of PM2.5 using meteorological data and an understanding of the factors leading to near source variability.
PEMs’ BC measurements also showed that near-source contributions to average wood smoke concentrations vary widely over relatively short distances. Based on the BC variations between the eight to twelve monitored locations, it is unreasonable to assume that the BC measurements, and hence wood smoke PM2.5, are constant over a residential area. The maximum PEM BC difference of 0.76 &#;g/m3, or a PM2.5 concentration of 12.7 to 19.0 &#;g/m3 (depending on the BC/ PM2.5 fraction), could result in inappropriate measures being taken to protect the health of local residents. This research showed significant concentration variability associated with wood smoke burning within a residential neighborhood, with an average standard deviation of 0.10 &#;g/m3 and a relative standard deviation of 77.2%. Since these average standard deviations and ranges of PEM BC concentration variability were calculated in Cambria, these BC/PM2.5 fractions can only be applied to Cambria, in particular, the 1 km2 study area. Given the BC concentration differences between each PEM measured in the residential study area and the Cambria Fire Station, ranging from 0.09 to 0.45 &#;g/m3, it is evident that the central monitoring station is not a reasonable proxy for the average wood smoke concentrations to which people are exposed.
Using meteorological data to estimate PM2.5 concentrations from residential wood smoke is difficult because it requires knowledge the number of homes burning, distance from burners, wind speed, inversion conditions and other parameters that have spatiotemporal variability. The multiple regression analysis between the meteorological predictors and BC concentration did not detect a significant correlation for any of the meteorological factors or burning conditions. The correlation between meteorological factors and BC concentration was weak because the meteorological data was unlikely representative of the true conditions within the study area, and a lack of repeatable meteorological conditions between IOPs. Based on the meteorological data collected for the IOPs, wind directions and speeds varied considerably from 6 to 9 p.m., between IOPs, with wind directions coming from all directions and surface inversions occurring during half of the IOPs.
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Van, Rooyen G. C. (Gert Cornelis). "Structural analysis in a distributed collaboratory." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53069.
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Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: Structural analysis is examined in order to identify its essential information requirements, its fundamental tasks, and the essential functionalities that applications which support it should provide. The special characteristics of the information content of structural analysis and the algorithms that operate on it are looked into and exploited to devise data structures and utilities that provide proper support of the analysis task within a local environment, while presenting the opportunity to be extended to the context of a distributed network-based collaboratory as well. Aspects regarding the distribution of analysis parameters and methods are analysed and alternatives are evaluated. The extentions required to adapt the local data structures and utilities for use in a distributed communication network are developed and implemented in pilot form. Examples of collaborative analysis are shown, and an evaluation of the overhead involved in distributed work is performed.
AFRIKAANSE OPSOMMING: 'n Ondersoek van die struktuuranalise-taak word uitgevoer waarin die kerninligtingsbehoeftes en fundamentele take daarvan, asook die vereisde funksionaliteit van toepassings wat dit ondersteun bepaal word. Die besondere eienskappe van struktuuranalise-inligting en die algoritmes wat daarop inwerk word ondersoek en benut om data strukture en metodes te ontwikkel wat die analise-taak goed ondersteun in In lokale omgewing, en wat terselfdertyd die moontlikheid bied om sodanig uitgebrei te word dat dit ook die taak in 'n verspreide samewerkingsgroepering kan ondersteun. Aspekte van die verspreiding van analiseparameters en metodes word ondersoek en alternatiewe oplossings word evalueer. Die uitbreidings wat nodig is om die datastrukture en metodes van die lokale omgewing aan te pas vir gebruik in verspreide kommunikasienetwerke word ontwikkel en in loodsvorm toegepas. Voorbeelde van samewerking-gebasseerde analise word getoon, en die oorhoofse koste verbonde aan analise in 'n verdeelde omgewing word evalueer.
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Douries, William John. "Factors influencing asphalt compactibility and its relation to asphalt rutting performance." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16311.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: This thesis covers the factors affecting compactibility of hot mix asphalt including gradation, filler/binder ratios, binder types, binder content, polymer modification, temperature, volumetric properties etc. The study is not limited to compactibility as the property measured, but also on the influence of these factors on the mix’s capacity to resist permanent deformation or rutting. An experimental design was used with a variety of the above factors being included. Laboratory analysis of the mixes as well as accelerated pavement testing of different mix types using the one-third scale Model Mobile Load Simulator (MMLS3) was carried out. The analysis assists in identification of the factors that influence both compactibility and rut resistance, those influencing the one but not the other, and those factors having no significant influence. The compactibility of the mixes has been analysed in terms of voids in the mix at a specific binder content and compaction level. Special consideration was given to the characterisation of the filler and filler/binder system of some mixes. It was found that gradation of a mix has a significant influence on compaction and the rutting performance. High filler/binder ratios were found to be the critical factors influencing the compactibility of the wearing course mixes investigated, but based on the limited tests performed, the reduction of the filler/binder ratios for improved compactibility did not significantly increase rutting under accelerated pavement testing. As expected, the binder type has a significant influence on the rutting resistance as well as compactibility. In addition, an increase in binder content facilitated compaction, but decreased rutting resistance. Polymer modification considerably improved the rutting resistance of a standard mix under the same loading conditions. Although some modifiers may improve rutting resistance, it requires higher compaction temperatures. The addition of the antistripping agent Gripper L decreased the rutting, aggregate stripping and also the rate of rutting of the Quartzite LAMBS mix that result from the stripping failuremechanism. Low densities can lead to considerable rutting and moisture damage, especially when a moisture susceptible aggregate is used. In terms of compactibility as evaluated with the Superpave Gyratory Compactor, it appears that there exists a temperature window in which compaction can be achieved, but in terms of rutting; even a small deviation in temperature can influence rutting results significantly. The control of the temperature during testing is critical if meaningful comparisons between different mixes with regard to rutting performance are to be made. Linear elastic and finite element analysis has been performed to ascertain whether different specimen geometries would influence the stress distribution within the specimen, and subsequently the rutting results. It was found that the geometry of test specimens has an influence on the stress distribution within the specimens, which can influence the permanent deformation results. The briquette specimens tested in the laboratory also yielded higher rutting results for the same mix tested in the field. It is therefore important to use specimens that are most representative of field conditions
AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die faktore wat ’n invloed het op die kompakteerbaarheid van warm asfalt. Faktore sluit in onder andere gradering, vulstof/bindstof verhouding, tipe bindstof, bindstof inhoud, polimeer modifisering, temperatuuur, volumetriese eienskappe, ens. Hierdie studie is nie net beperk tot kompakteerbaarheid as ‘n gemete eienskap nie, maar ook die invloed van hierdie faktore op die mengsel se vermoë om weerstand te bied teen permanente deformasie of spoorvorming. ’n Eksperimentele ontwerp wat ’n verskeidenheid van bogenoemde faktore insluit is gebruik. Laboratorium analise van die mengsels asook versnelde plaveisel toetse van die verskillende tipe mengsels is gedoen met die een-derde skaal Mobiele Lassimuleerder (MMLS3). Die analise help met die identifikasie van die faktore wat beide kompakteerbaarheid en spoorvorming beïnvloed, asook dié wat slegs die een maar nie die ander beïnvloed, en ook die faktore wat geen beduidende invloed het nie. Die kompakteerbaarheid is geëvalueer in terme van die hol ruimtes in die mengsel by ’n bepaalde bindstof inhoud en verdigtingsgraad. Spesiale aandag is geskenk aan die eienskappe van die vulstof en vulstof/bindstof wisselwerking van die mengsels. Die gradering van ’n mengsel het ’n beduidende invloed op kompakteerbaarheid sowel as spoorvorming. Hoë vulstof/bindstof verhoudings is een van die kritiese faktore wat die kompakteerbaarheid van die betrokke mengsels beïnvloed, maar laer vulstof/bindstof verhoudings vir beter kompaksie het nie ’n beduidende toename in wielsporing teweeg gebring nie. Soos verwag het die tipe bindstof ’n beduidende invloed op kompakteerbaarheid sowel as spoorvorming. ’n Toename in bindstof bevorder verdigting, maar lei tot groter wielsporing. Polimeer modifisering verminder die wielsporing van ’n standard mengsel onder dieselfde beladingstoestand. Alhoewel modifisering wielsporing verminder, vereis dit hoër kompaksie temperature.Die toevoeging van die teenstropingsmiddel GripperL verminder spoorvorming, aggregaat stroping asook die tempo van spoorvorming van die Kwartsiet LAMBS mengsel as gevolg van die stropingsmeganisme. Lae digthede kan lei tot aansienlike vogskade en spoorvorming; veral as die aggregaat vatbaar is vir die invloed van vog. Daar blyk ’n temperatuur interval te wees waarin verdigting met die Superpave Gyratory Compactor bereik kan word; maar selfs ‘n klein temperatuurafwyking kan beduidende invloed op die resultate van spoorvorming hê. Temperatuurbeheer is baie belangrik indien sinvolle vergelykings tussen die sporingsgedrag van verskillende mengsels gemaak moet word. Lineêr elasties en eindige element analise is uitgevoer om te bepaal of verskillende toetskonfigurasies die spanningsverdeling binne die toetsmonsters en die spoorvorming affekteer. Dit is bevind dat die geometrie van toetsmonsters het ’n invloed op die spanningsverdeling in die monsters wat die sporingsresultate kan beïnvloed. Die briketmonsters in die laboratorium gee ook groter spoordiepte teenoor dieselfde mengsel wat in die veld getoets is. Daarom is dit belangrik om verteenwoordigende monsters te gebruik.
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Dzvukamanja, T. N. (Tembiwe Nunana). "Development of provisional guidelines for the treatment of scale and resolution in assessing streamflow reduction impacts of alien plant infestations and commercial afforestation in water resources modelling studies." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50319.
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Thesis (MScEng)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Experiments conducted on afforested catchments in South Africa have shown that alien trees can cause substantial reductions in catchment runoff (Scott et ai, 2000). In recognition of the impact which alien trees can have on the country's water resources, commercial afforestation was declared a stream flow reduction activity (SFRA) in terms of the National Water Act (NW A) (No. 36 of 1998), and the Department of Water affairs and forestry launched the Working for Water Programme (WfW) in 1995 with the recovery of water resources lost to Invasive alien plants (lAPs) as one of the Programme's objectives. These initiatives have intensified the need to quantify SFR; for example, for licensing purposes to satisfy the requirements of the NWA and for predicting the effects of lAP clearing by WfW projects. Of interest to water resources practitioners, is the impact of SFR on mean annual runoff (MAR), on low flows and on water resource system, or reservoir, yield. In South Africa two basic methods of streamflow reduction (SFR) estimation have been developed for commercial afforestation and lAPs. These are • free-standing empirical relationships in the form of the CSIR SFR CUNes, used in conjunction with the monthly, calibration-based, Pitman model. • component modules in the physically-based, land-use sensitive ACRU rainfall-runoff catchment model, run at a daily time step with relatively fine subcatchment delineation. There has been a strong need for an evaluative comparison of the impacts of SFR estimated via these two methods. This study aimed to meet this need by using both methods to estimate SFR for a number of commercial afforestation and lAP scenarios in three study systems, the Berg, Sabie and Mhlatuze, representing different bioclimatic conditions in South Africa, and running the SFR sequences from the two estimation methods through the Water Resources Yield Model to determine the impact of the SFR on yield. The analysis differentiated between upland and riparian SFR, and between SFR produced by different tree classes. Study conclusions included the following points: • Both the ACRU and SHELL models are capable of achieving a reasonable average seasonal correspondence of high and low flows with the observed averages, though the actual averages produced by the two models can differ substantially. In general, ACRU simulates less SFR than SHELL, and gains in SFR after afforestation or invasion by lAPs may be simulated by ACRU during dry periods. The selection of crop factors for different plant species has a strong influence on the relative water use of the species modelled in ACRU. • The impacts on yield of SFR due to lAPS and afforestation tends to be greater than the impact on MAR, and impacts tend to be more severe for small subcatchments than for the total catchment. A simulated reduction in MAR can result in a simulated increase in yield of a given assurance, if the portion of the flow sequence occurring during the critical period is dominated by streamflow gains, and vice versa. Research recommendations centred on improving the availability of reliable field measurements of parameters and processes required tor the effective modelling of SFR. Based on the results of the study, guidelines were formulated for SFR modelling, focussing on the choice of SFR estimation method and the treatment of various parameters and considerations which influence the outcomes of SFR modelling.
AFRIKAANSE OPSOMMING: Eksperimente wat in bebosde opvanggebiede in Suid-Afrika uitgevoer is, het getoon dat uitheemse bome aansienlike verminderings in opvanggebied-afloop kan veroorsaak (Scott et al,2000). Ter erkenning van die impak wat uitheemse bome op die land se waterbronne kan he, is kornrnersiele bebossing verklaar as 'n stroomvloei-verminderingsaktiwiteit (SVVA) in terme van die Nasionale Waterwet (NWW) (Nr. 36 van 1998). Die Departement van Waterwese en Bosbou het ook die Werk-vir-Water Program (WvW) in 1995 geloods met, as een van die doelwitte, die herwinning van waterbronne wat deur uitheemse indringerplante (UIPe) opgebruik word. Hierdie inisiatiewe het die behoefte om SVV te kan kwantifiseer verskerp; by voorbeeld; for liksensiermqsdoeleindes om die vereistes van die NWW te bevredig, of om die impakte van UIP-opruiming in WvW-projekte te voorspel. Van besondere belang vir waterbron-praktisyns is die impak van SVV op gemiddelde jaarliks afloop (GJA), op lae vloeie en op die lewering van waterbronne, of -stelsels. In Suid-Afrika is twee basiese metodes vir SVV-raming ontwikkel vir komrnersiele bebossing en UIPe, soos volg: • losstaande empiriese verbande in die vorm van die WNNR se SVV-krommes, wat gebruik word saam met die maandelikse, kalibrasie-gebaseerde, Pitman-model wat in die SHELL-sagteware-omgewing ingebou is. • Modules wat komponente vorm in die fisies-gebasserde, grondgebruik-gevoelige ACRU reenval-atloop opvanggebiedmodel, wat op 'n daaglikse tydstap loop, met relatiewe fyn subopvanggebied-indelings. Daar bestaan al lank 'n sterk behoefte aan 'n takserende vergelyking van die impakte van SVV so os geraam via hierdie twee metodes. Hierdie navorsing het beoog om hierdie behoefte te bevredig deur beide metodes in 'n aantal kornrnersiele bebossings- en UIPscenario's in drie stelsels, die Berg, Sabie en Mhlatuze, te gebruik. Sodoende word drie verskillende bio-klimaatstreke gedek. Die maandelikse SVV-tydreekse van die twee ramingsmetodes was toe ingevoer in 'n waterbronstelselmodel (WRYM) om die impak van die SVV op die lewering te bepaal. Die ontledings het tussen oewer- en nie-oewer-SVV, asook tussen SVV wat deur verskillende boom-klasse veroorsaak is, onderskei. Die gevolgtrekkings uit die studie het die volgende punte ingesluit: • Seide die ACRU- en SHELL-modelle is in staat om 'n redelike ooreenkoms in seisoenale hoe en lae vloeie met waargenome gemiddeldes te verskaf, alhoewel die eintlike gemiddeldes wat deur die twee modelle gelewer word, aansienlik kan verskil. • Oor die algemeen simuleer ACRU laer SVV as SHELL en klein toenames in vloeie na bebossing of indringing deur UIPe kan soms tydens droe tydperke deur ACRU gesimuleer word. Die keuse van gewasfaktore vir verskillende planttipes het 'n groot invloed op die relatiewe waterverbruik van die planttipes wat in ACRU gemodelleer word. • Die impakte op lewering van SVV te wyte aan beide UIPe en bebossing neig om groter te wees as die impak op GJA, en die impakte neig om meer ernstig te wees vir klein subopvanggebiede as vir die totale opvanggebied. 'n Gesimuleerde vermindering in GJA kan soms saamval met 'n gesimuleerde toename in lewering teen 'n spesifieke betroubaarheid, as die gedeelte van die tydreeks wat gedurende die kritieke tydperk voorkom, heelwat UIP-gebaseerde stroomvloei-toenames bevat en vice versa. Navorsingsaanbevelings fokus op die verbetering van die beskikbaarheid van betroubare veldwaarnemings van parameters en prosesse wat vereis word vir betroubare modellering van SVV. Riglyne vir SVV-modellering is geformuleer, gebaseer op die resultate van hierdie navorsing, met 'n fokus op die keuse van SVV-ramingsmetode, die behandeling van verskeie parameters en oorwegings wat die uitslag van SVV-modellering sou kon bemvloed.
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Canto, R. R. "The rating of compound sharp-crested weirs under modular and non-modular flow conditions." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/52005.
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Thesis (MEng)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: The compound sharp-crested weir, which consists of two or more notches at different elevations, is the most common type of flow gauging structure found in South Africa. The Department of Water Affairs and Forestry (DWAF) is responsible for the operation of these weirs. They are currently experiencing the following problems regarding flow measurement with compound sharp-crested weirs: 1. During free-flow conditions, also known as modular flows, there is uncertainty about the accuracy of the discharge formulas. Although reliable formulas exist for single notch weirs, it is not clear how they should be modified for compound weirs. Whilst methods have already been developed to deal with compound weirs their accuracy needs to be investigated further. 2. When the weirs become submerged during floods, the upstream water head is affected by downstream water levels and the original formulas are not applicable. It has so far been impossible to calculate discharge accurately under these so-called non-modular flow conditions. This report summarises the findings of an extensive study which addressed the issues mentioned above. A comprehensive test programme was completed during which variations of compound sharp-crested weirs were tested under both modular and non-modular flow conditions. In the development of new methods care was taken to adhere to internationally accepted standards. This should make South African practice acceptable to others. One important characteristic of compound weirs is the presence of end contractions. It was found that they have a significant effect on discharge measurement. Generally, the more a weir is contracted, the lower its coefficient of discharge becomes. It was also established that end contractions can ensure excellent aeration for compound weirs. For modular flow conditions it was possible to develop a discharge formula based on the IMFf equation, which is included in the ISO standards. This new method was found to produce the smallest errors when compared to other existing formulas (average error 0.6%). During non-modular flow conditions it was noted that end contractions also play an important role, at least during the early stages of submergence. In full-width weirs the upstream water level tends to drop first (due to de-aeration) before it rises again with increasing submergence. Weirs with end contractions do not suffer from this problem. It was further established that the effect of submergence could be described in terms of an energy loss occurring at the drowned weir. This energy loss is a function of the velocities at the so-called vena contracta of the weir and at the downstream river cross section. As the difference between these velocities increases, the energy loss increases as well. Two methods were tested to estimate the discharge under submerged conditions. The Villemonte formula works well if the energy losses at the weir are relatively high, while the Wessels method is reliable if the energy losses become smaller. A procedure was developed which indicates when each method is applicable. The test data indicated that the maximum error is up to ±10% at high submergence ratios (S> 0.80) if this procedure is followed.
AFRIKAANSE OPSOMMING: Multikeep-skerpkruinmeetstrukture bestaande uit twee of meer kepe op verskillende vlakke word meestal gebruik om vloeie in Suid-Afrikaanse riviere te meet. Die Departement van Waterwese en Bosbou (DWAF) is verantwoordelik vir die instandhouding van sulke meetstrukture. Hulle ervaar tans die volgende probleme met vloeimeting by multikeepskerpkruine: 1. Gedurende modulêre (onversuipte) toestande bestaan daar nog onsekerheid oor die akkuraatheid van die formules wat gebruik word om vloeitempo's te bereken. Alhoewel betroubare formules ontwikkel is vir enkelkepe, is dit nie duidelik hoe hulle aangepas kan word sodat hulle ook vir multikepe gebruik kan word nie. Die akkuraatheid van sommige bestaande metodes vir multikepe moet ook ondersoek word. 2. Onder versuipte toestande word die stroom-op watervlak beïnvloed deur die stroom-af watervlak en die formules vir vry-vloei toestande is nie geldig nie. Dit was tot nou toe nie moontlik om vloeitempo ' s akkuraat te bereken onder hierdie nie-modulêre toestande nie. Hierdie verslag bied 'n opsomming van die bevindinge van 'n navorsingsprojek wat bogenoemde probleme aangespreek het. 'n Toetsprogram is uitgevoer wat moontlike konfigurasies van multikepe ingesluit het. Die modelle van die meetstrukture is onder beide vry-vloei en versuipte toestande bestudeer. Gedurende die ontwikkeling van nuwe formules vir die berekening van vloeie is daarna gestreef om so veel as moontlik gebruik te maak van internasionale standaarde. Dit behoort Suid-Afrikaanse praktyke vir andere aanvaarbaar te maak. 'n Belangrike eienskap van multikepe is die voorkoms van end-kontraksies. Hulle het 'n groot invloed op vloeimeting en oor die algemeen het 'n keep met groot end-kontraksies 'n laer vloei koëffisient as 'n vol-wydte keep. End-kontraksies is ook baie effektief om skerpkruine te belug. Vir vry-vloei toestande is gevind dat 'n metode gebaseer op die IMFT vergelyking (ingesluit in ISO standaarde) baie goeie resultate lewer. In vergelyking met ander bestaande metodes gee dié metode die kleinste foute met 'n gemiddelde fout van 0.6%. Onder versuipte toestande speel end-kontraksies ook 'n belangrike rol, ten minste by beperkte versuiping. As vol-wydte kepe beskou word, kan gesien word dat die stroom-op watervlak eers daal voordat dit weer styg (weens ontlugting). Kepe met end-kontraksies ly nie aan hierdie probleem nie. Dit is verder bevestig dat versuipte toestande beskryf kan word in terme van 'n energie verlies wat by die versuipte meetstruktuur voorkom. Hierdie energie verlies is 'n funksie van die snelhede by die vena contraeta van die keep en by die stroom-af rivier snit. As die verskil tussen die twee snelhede groot is, is die energie velies ook groot. Twee bestaande metodes vir versuipte toestande is getoets. Villemonte se vergelyking werk goed as die energie verliese groot is, terwyl Wessels se metode beter werk as die verliese klein raak. 'n Prosedure is ontwikkel wat dit moontlik maak om die regte metode te kies vir 'n spesifieke toestand. Vanaf die toetsdata is bepaal dat die maksimum fout ±10% is by hoë grade van versuiping (S> 0.80) wanneer bogenoemde prosedure gevolg word.
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Visser, Christo Riaan. "Mechanical and structural characterisation of extrusion moulded SHCC." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/18712.
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Thesis (MScIng)--University of Stellenbosch, 2007.ENGLISH ABSTRACT: SHCC (Strain-Hardening Cement-based Composite) is a type of HPFRCC (High Performance Fibre Reinforced Cement-based Composite) that was designed and engineered to overcome the weaknesses of ordinary concrete. It shows a high ductility as it can resist the full tensile load at a strain of more than 3%. This superior response is achieved with multiple cracking under tensile loading which has a pseudo strain-hardening phenomenon as a result. The purpose of the research project reported in this thesis document was to design and build a new piston-driven extruder for the production of SHCC as well as R/SHCC (reinforced SHCC) elements and to investigate and characterise the structural and mechanical behaviour of extrusion moulded SHCC. A new piston-driven extruder, specifically for academic purposes, was designed based on the principles of fluid flow mechanics. Although fluid flow is not an ideal model to represent the flow of viscous material through an extruder, it was deemed sufficient for this specific study. A new extruder with the capacity to extrude SHCC and R/SHCC was built. Provision was made that this extruder can be fitted with extruder dies and transition zones of varying shapes and sizes. A comparative study between unreinforced as well as reinforced cast SHCC and extruded SHCC as well as a suitable R/C (Reinforced Concrete) was conducted. Three-point bending tests, representative of the envisioned structural application, were performed on specimens of each of the composites. The unreinforced cast SHCC and especially the unreinforced extruded SHCC have a comparative level of performance to the cast R/C. These specimens displayed a similar cracking pattern of multiple cracks, although less pronounced in the extruded SHCC. The extruded SHCC has superior first cracking and ultimate strength in comparison to cast SHCC, but with accompanying lower ductility. The reinforced SHCC specimens failed in a combination of flexure and shear. The extruded R/SHCC specimens formed multiple diagonal cracks before failure, while the cast R/SHCC specimens formed only a few diagonal cracks, before delaminating along the reinforcement. The higher shear capacity and thus the ability to form multiple diagonal cracks of the extruded R/SHCC can be ascribed to the better fibre orientation of the specimens in the longitudinal direction, while the cast specimens have a random orientation of fibres. R/SHCC and especially extruded R/SHCC could be a far superior structural material to R/C. Mechanical characterisation of extruded SHCC was done with the use of uni-axial tensile and compressive tests. The results of these tests were compared with the results of uni-axial tensile tests previously performed on cast SHCC as well as uni-axial compressive tests that were performed on cast SHCC in this research study. The extruded SHCC displayed superior tensile performance in terms of first cracking and ultimate strength in comparison to cast SHCC, but with accompanying lower ductility. In terms of compressive performance the extruded SHCC has a higher ultimate strength, but with a lower ductility than cast SHCC. The extruded SHCC also has a much higher E-modulus than cast SHCC. This can partly be attributed to the difference between the water/binder ratios of the cast and extruded SHCC, but can mainly be ascribed to the lower porosity as a result of high extrusion forces involved in the manufacturing of extruded SHCC. A simple bending model for SHCC has also been introduced. This model is based on the mechanical characteristics of SHCC. The model somewhat underestimates the resistance moment of the extruded and cast SHCC, but this underestimation is more pronounced in the case of the cast SHCC. Various reasons for the underestimation is discussed, but it is postulated that the main reason for the difference in experimentally determined and the calculated resistance moment of the cast SHCC is the possible variation in ingredient properties and specimen preparation and testing, since the characterisation of the cast SHCC was done over a long period of time and by different researchers. The bending model is however deemed sufficient for the design purposes of SHCC.
AFRIKAANSE OPSOMMING: SHCC (“Strain-Hardening Cement-based Composite”) is ‘n tipe HPFRCC (“High Performance Fibre Reinforced Cement-based Composite”) wat ontwerp is om die swakhede van gewone beton te oorkom. Hierdie materiaal het ‘n hoë duktiliteit en kan die volle trekkrag weerstaan met ‘n vervorming van meer as 3%. Hierdie uitstaande gedrag word gekenmerk deur meerdere krake wat vorm gedurende ‘n trek belasting wat vervormingsverharding tot gevolg het. Die doel van die navorsingsprojek wat weergegee word in hierdie tesis dokument was om ‘n nuwe suier-aangedrewe ekstrueerder vir die produksie van SHCC sowel as R/SHCC (bewapende SHCC) te ontwerp en te bou en om die strukturele en meganiese gedrag van ge-ekstrueerde SHCC te ondersoek en te karakteriseer. ‘n Nuwe suier-aangedrewe ekstrueerder, spesifiek for akademiese doeleindes, is ontwerp gebaseer op die beginsels van vloeistof vloeimeganika. Alhoewel vloeistof vloeimeganika nie ‘n ideale model is vir die voorstelling van die vloei van ‘n viskose materiaal deur ‘n ekstrueerder nie, word dit beskou as aanvaarbaar vir die doeleindes van hierdie spesifieke studie. ‘n Nuwe ekstrueerder met die kapasiteit om SHCC en R/SHCC te ekstrueer is gebou. Voorsiening is ook gemaak dat ekstrueerder vorms (“dies”) en oorgangsones van verskillende vorms en groottes aan die ekstrueerder geheg kan word. ‘n Vergelykende studie tussen onbewapende sowel as bewapende gegote en ge-ekstrueerde SHCC, sowel as ‘n gepasde R/C (“Reinforced Concrete”) is uitgevoer. Drie-punt buigtoetse, verteenwoordigend van die voorgestelde strukturele toepassings vir SHCC, is uitgevoer op proefstukke van elk van die bogenoemde materiale. Die meganiese gedrag van die onbewapende gegote SHCC en spesifiek die onbewapende geekstrueerde SHCC is vergelykbaar met die meganiese gedrag van gegote R/C. Hierdie proefstukke het ooreenstemmende kraakpatrone van veelvuldige krake getoon, alhoewel dit minder prominent was in die geval van ge-ekstrueerde SHCC. Die ge-ekstrueerde SHCC het hoër eerste kraak- en maksimum sterktes in vergelyking met gegote SHCC, maar met gepaardgaande laer duktiliteit. Die bewapende SHCC proefstukke het in ‘n kombinasie van buig en skuif gefaal. Die geekstrueerde R/SHCC proefstukke het meerdere diagonale krake gevorm voor faling, terwyl die gegote R/SHCC proefstukke slegs ‘n paar diagonale krake gevorm het, voordat dit langs die bewapening gedelamineer het. Die hoër skuifkapasiteit van ge-ekstrueerde SHCC en dus die vermoë om meerdere diagonale krake te vorm, kan toegeskryf word aan die longitudinale orientasie van vesels van die proefstukke, terwyl gegote proefstukke se vesels meer lukraak georienteerd is. R/SHCC en spesifiek ge-ekstrueerde R/SHCC kan‘n superieure strukturele materiaal in vergelyking met R/C wees. Die meganiese karakterisering van ge-ekstrueerde SHCC is gedoen met die gebruik van direkte trek- en druktoetse. The resultate van die hierdie toetse is vergelyk met die resultate van direkte trektoetse uit ‘n vorige studie op gegote SHCC,, sowel as met die uitslae van direkte druktoetse wat op gegote SHCC in hierdie navorsingstudie gedoen is. Die ge-ekstrueerde SHCC het superieure trekgedrag in terme van eerste kraak en maksimum sterktes in vergelyking met gegote SHCC getoon, maar met gepaardgaande laer duktiliteit. In terme van drukgedrag het die ge-ekstrueerde SHCC ‘n hoër maksimum druksterkte, maar met ‘n laer duktiliteit in vergelyking met die gegote SHCC. Die ge-ekstrueerde SHCC het ook ‘n veel hoër Emodulus as gegote SHCC. Dit is gedeeltelik as gevolg van die verskil in die water/binder verhouding van die gegote en ge-ekstrueerde SHCC, maar kan grootliks toegeskryf word aan die laer porositeit van ge-ekstrueerde SHCC as gevolg van die hoë ekstrusie kragte. ‘n Eenvoudige buigmodel vir SHCC word ook voorgestel. Hierdie model is geabseer op die meganiese gedrag van SHCC. Die model onderskat die weerstandsmoment van ge-ekstrueerde SHCC sowel as gegote SHCC, maar hierdie onderskatting is meer prominent in die geval van gegote SHCC. Verskeie redes vir hierdie onderskatting word genoem, maar dit word beweer dat in die geval van gegote SHCC dit grootliks as gevolg van moontlike variasies in die materiaal eienskappe en proefstukke se voorbereiding en toetsing is, aangesien die karakterisering van die gegote SHCC oor ‘n lang tydperk en deur verskillende navorsers gedoen is. Die buigmodel word nogtans as voldoende beskou vir die ontwerpdoeleinde van SHCC.
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Bruce, H. G. S. "The rating of sluicing flumes in combination with sharp-crested and crump weirs under modular and non-modular flow conditions." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/52006.
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Thesis (MEng)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: As part of a previous WRC project, three types of sluicing flumes were developed for use in compound weirs in combination with sharp-crested and crump weirs, (Rossouw et al., 1998). These sluicing flumes have several advantages which make them ideal structures for flow measurement in South African rivers. These are a high modular limit, stable modular flow characteristics, an ability to measure a wide range of flows accurately, as well as good sediment handling characteristics. These three flumes have been calibrated under modular or free flow conditions in combination with sharpcrested and crump weirs. There is a high degree of variability of flow in South African rivers. Flood discharges are part of this variability, and can form an important part of the mean annual runoff. Measuring weirs cannot always be built so that they do not become submerged during floods, but it is nevertheless important that flood discharges be recorded. It is therefore important that these compound weirs be calibrated for flow measurement under non-modular or submerged conditions. The purpose of the research undertaken for this WRC project is to find a method to calculate the non-modular discharge over compound weirs consisting of sluicing flumes in combination with sharp-crested and crump weirs. By analysis of existing data from the previous WRC project, as well as data from laboratory tests undertaken as part of this project, the submergence effect of sluicing flumes has been quantified. A range of configurations of sharp-crested weirs as well as crump weirs in combination with the sluicing flume have been tested. A new method has been developed to calculate the submerged discharge over these compound weirs. This method is suitably accurate, and can be recommended to the DWAF for use. The calculation procedure that must be followed in order to calculate the submerged discharge over these compound weirs becomes rather complicated due to the iterations that must be carried out. In order to clarify these procedures, flow charts are provided which set out the steps that must be followed. Calibration curves for all the combinations of compound weirs analysed in this report are also provided. These can be used to obtain estimates of the discharge in the field, and can also be used as a check on any calculations carried out. The principal goal of this project, namely that of finding a suitably accurate method to calculate the non-modular discharge over these compound weirs has therefore been achieved.
AFRIKAANSE OPSOMMING: As deel van 'n vorige Water Navorsings Kommisie (WNK) projek, is drie spoelgeute ontwikkel vir gebruik in saamgestelde meetwalle in kombinasie met skerp-kruin en Crump oorlope, (Rossouwet al., 1998). Die spoelgeute het eienskappe wat hulle gunstig maak vir vloeimeting in Suid Afrikaanse riviere. Vanhierdie eienskappe is 'n hoë modulêre limiet, stabiele modulêre vloei eienskappe, goeie sediment hanterings eienskappe en 'n vermoë om oor 'n wye bereik vloeie akkuraat te kan meet. Hierdie drie geute is in kombinasie met skerpkruin en Crump oorlope gekalibreer onder vryvloei toestande. Vloeie varieër baie in Suid Afrikaanse riviere. Vloede is deel van hierdie variasies en maak 'n belangrike deel uit van die gemiddelde jaarlikse afloop. Meetwalle kan nie altyd gebou word sodat hulle nie versuip tydens vloede nie, maar dit is nogtans belangrik dat hierdie vloeie gemeet word. Daarom is dit belangrik dat saamgestelde meetwalle gekalibreer is vir vloeimeting onder versuipte of nie-modulêre toestande. Die doel van die navorsing wat gedoen is vir hierde WNK projek was om 'n geskikte metode te ontwikkel om die nie-modulêre vloeie oor saamgestelde meetwalle, wat bestaan uit spoelgeute in kombinasie met skerpkruin en Crump oorlope, te kan bereken. Met die analise van bestaande data van die vorige WNK projek, asook data van labratoriumtoetse wat gedoen is as deel van hierdie projek, is die versuiping van spoelgeute beskryf. 'n Hele reeks skerpkruin asook crump oorlope is getoets in kombinasie met die spoelgeute. 'n Nuwe metode is ontwikkel om die nie-modulêre vloei oor hierdie saamgestelde meetstrukture te kan bereken. Hierdie metode IS akkuraat genoeg om aan die Departement van Waterwese te kan aanbeveel. Die berekingsproses wat gevolg moet word om die versuipte vloei oor die saamgestelde meetstrukture te bereken, raak ingewikkeld as gevolg van die iterasies wat uitgevoer moet word. Vloeidiagramme is opgestel wat hierdie prosedures duidelik uiteensit. Kalibrasie kurwes is ook ontwikkel vir al die kombinasies van saamgestelde meetwalle wat geanaliseer is in hierdie verslag. Hierdie kurwes kan gebruik word om skattings te maak van vloeie in die veld, maar ook om enige berekings wat gedoen is te kontroleer. Die hoofdoel van hierdie projek, naamlik om 'n geskikte metode te ontwikkel wat die nie-modulêre vloeie oor saamgestelde meetwalle akuraat kan bereken, is bereik.
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Theron, Louis Francois. "Personnel Allocation for Engineering Projects." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86295.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The logical allocation of tasks in engineering offices currently relies heavily on the experience and intuition of project managers. In large scale projects the complexity of the task allocation procedure exceeds the capacity of human intuition, and a systematic technique is required to aid project managers in assigning tasks to individuals. In this project such a systematic technique is modelled and implemented using the Java programming language. An equation was developed to calculate an individual’s workload, and used in conjunction with other criteria to intelligently and systematically select an optimal individual to complete engineering tasks. The software solution is network-based, and also aims to aid project managers in various managerial duties.
AFRIKAANSE OPSOMMING: Die logiese toekenning van ingenieurstake steun tans swaar op die ervaring en aanvoeling van projek bestuurders. In grootskaalse projekte is die kompleksiteit van die taak toekenningsproses veel groter as die kapasiteit van menslike intuïsie. Dus word ‘n sistematiese proses wat projek-bestuurders kan help met die toeken van take aan individue vereis. In hierdie projek is so 'n sistematiese tegniek ontwikkel en geïmplementeer met behulp van die Java-programmeringstaal. 'n Vergelyking is ontwikkel om 'n individu se werklading te bereken en is in samewerking met ander kriteria gebruik om take intelligent en sistematies toe te ken. Die sagteware is network en databasis-gebaseerd en kan ook gebruik word om projek-bestuurders te help met verskeie bestuurspligte.
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Kumar, Sujay V. "Vitri - A Generic Framework for Engineering Decision Support Systems on Heterogeneous Computer Networks." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-20020225-084940.
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Vitri is an object-oriented framework implemented in Java for high-performancedistributed computing. Using Vitri, applications can engage in cooperativeproblem solving by dividing their tasks among heterogeneous clusters of workstations and PCs. Vitri's features include basic support fordistributed computing and communication, as well as visual tools for evaluating run-time performance, and modules for heuristic optimization. It balances loads dynamically using a client-side task pool, allows theaddition or removal of servers during a run, and provides fault tolerance transparently for servers and networks. Among its more powerful featuresare modules for heuristic optimization and decision support tools such asmodeling to generate alternatives (MGA). Vitri also provides an asynchronous global-parallel genetic algorithm that is particularly suited for coarse-grained tasks executing on processors with large variations in processor speeds. By using dataflow techniques, in which computations areexplicitly based on the availability and forwarding of data, the usual end-of-generation synchronization points are removed from the algorithm. The tools in Vitri are applied to a number of different applicationsfrom the civil engineering domain. The results indicate the adaptability of Vitri to various problems and its utility as a tool for managing engineering decision support systems.
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Nuntasunti, Suchart. "The Effects of Visual-Based Information Logistics in Construction." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-01052004-212738/.
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The construction industry has, for sometime, suffered from stagnant productivity, high accident rate, project delays, and poor quality. Research studies have shown that the major cause of these performance problems is the lack of effective communication. This research was launched to investigate the usefulness of a comprehensive information logistics model on construction process performance. In order to test and validate key components of the model, a prototype network system named Visual-based Integrated Wireless Site (V-IWS) was developed and tested on a mid-size building construction project. The system was designed to allow every project participant access to real-time visual images of the jobsite and share information interactively with each other as well as with a central database through the Internet. It was developed and evaluated for 7 months in 2003. During the same time, the communication channels adopted by the general contractor, R.N. Rouse, and on-site meetings were observed and analyzed. This analysis indicated that most of the information shared among participants of this project could be handled electronically by the V-IWS. It was demonstrated that the V-IWS: a) reduces production waste and non value-added activities such as material delivery time, b) eliminate the need for unnecessary site visits and meetings, c) adds significant value to project participants by automatically creating visual as-built and picture archives, d) provides operational how-to training for crew, and e) increases site safety and security through automated monitoring. The system is scaleable and more network devices can be added as the building grows. While this study proved technical feasibility of the V-IWS, it became evident that trust, collaboration and information sharing among participants were critical success factors. Due to the industry?s traditional low-bid competition and aversion to change, it is crucial to understand how costs and benefits be distributed. Value sharing as well as technology adoption process need to be studied in order to ensure successful implementation of the system.
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Liao, Jiangying. "Quantifying Activated Sludge Bulking-Causative Filamentous Bacteria Using Molecular Methods." NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-01222003-102459/.
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Filamentous bulking is a widespread problem in activated sludge wastewater treatment plants. In North Carolina, 63% of wastewater treatment plants (WWTPs) surveyed have experienced bulking. Determining the dominant bulking-causative bacteria and their level of proliferation is a necessary step in bulking control. This study used molecular techniques, i.e. quantitative Fluorescent in situ Hybridization (FISH) and membrane hybridization to identify and quantify the specific filamentous microorganisms and their threshold values for causing bulking in both lab scale reactors and full scale treatment plants. Filament length of a specific filamentous organism, Eikelboom Type 1851, correlated strongly with the sludge volume index (SVI) and was identified to be the major bulking-causative microorganism in lab scale reactors and a full scale activated sludge plant. The full scale plant is a biological nutrient removal (BNR) plant, a common operational mode in North Carolina, suggesting that this organism may be prevalent in North Carolina WWTPs. The threshold value for Eikelboom Type 1851-caused-bulking was determined. This threshold value will allow the monitoring of incremental improvements in control methods and the delineation of the niche of Eikelboom Type 1851 in activated sludge. Furthermore, the lab scale experiments verified the kinetic selection theory and the filamentous backbone theory for Type 1851.
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Grasso, Barton. "Benchmarking the Management of Construction Programs." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-03222007-001859/.
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The management of large capital improvement construction programs involves the efforts of both internal staff and external service providers. An understanding of how construction programs are managed, either through internal or external staff, is essential in tracking future trends and determining improvements and best practices in the management process. To address this need a survey was developed by a focus group of industry professionals. The survey was distributed to the membership of a number of professional organizations that represented owners within the construction industry. The survey attempted to determine both the current status of managing a construction program throughout a broad range of demographic characteristics (including the definition of program management) and the hiring of an external program manager. The survey and subsequent analysis that focused on the management of a construction program examined the following key points: role of a program manager, internal capabilities, outsourcing, sourcing strategy, and management costs. The survey and subsequent analysis that focused on hiring an external program manager examined: program management fees, type of firms used in managing a construction program, factors considered when hiring a program manager, and organizational structure. The results of the survey have also been segregated by public and private organizations to denote any differences in the management of public and private construction programs. A key contribution of this research was determining the percentage of outsourcing within each phase of the construction process and the number of service providers considered in the selection process. Also, a multifaceted definition of program management was developed from the research for use in clarifying the concept of program management within construction.
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Tagliaferri, Anthony Paul. "Use and Comparison of Traffic Simulation Models in the Analysis of Emergency Evacuation Conditions." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-03232005-185245/.
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The evacuation of vulnerable coastal areas in the event of an emergency such as an impending hurricane has become a significant safety issue due to the rapid growth of both permanent and tourist populations in these areas. Highway capacity has often not been upgraded in line with this demand growth. In the case of Hurricane Floyd in 1999, evacuations of areas of North and South Carolina resulted in several highly congested primary highways and, as a result, several states created Lane Reversal Plans for interstates and/or divided highways along evacuation routes. However, these plans were created with little data to rely on as to their efficiency. A major research study was funded by the North Carolina Department of Transportation (NCDOT) to use simulation modeling to investigate the effects of the Interstate 40 Lane Reversal Plan on the evacuation of Wilmington and New Hanover County, North Carolina. In addition to the analysis of the effects of lane reversal, a side-by-side comparison of the CORSIM and VISSIM simulation models was performed on the highway network based on demand estimates provided by a demand study performed for the United States Army Corps of Engineers and the Federal Emergency Management Agency (FEMA). Analysis using CORSIM and VISSIM showed lane reversal to provide considerable capacity increases to traffic attempting to exit New Hanover County via Interstate 40, which had significantly increased throughput and decreased queues within New Hanover County in the event of large-scale evacuations.
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Devineni, Naresh. "Seasonal Hydroclimatology of the Continental United States: Forecasting and its Relevance to Water Management." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-03252010-193310/.
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Recent research in seasonal climate prediction has focused on combining multiple atmospheric General Circulation Models (GCMs) to develop multimodel ensembles. A new approach to combine multiple GCMs is proposed by analyzing the skill of candidate models contingent on the relevant predictor(s) state. To demonstrate this approach, we combine historical simulations of winter (December-February, DJF) precipitation and temperature from seven GCMs by evaluating their skill â represented by Mean Square Error (MSE) â over similar predictor (DJF Nino3.4) conditions. The MSE estimates are converted into weights for each GCM for developing multimodel tercile probabilities. A total of six multimodel schemes are considered that includes combinations based on pooling of ensembles as well as based on the long-term skill of the models. To ensure the improved skill exhibited by the multimodel scheme is statistically significant, we perform rigorous hypothesis tests comparing the skill of multimodels with individual modelsâ skill. The multimodel combination contingent on Nino3.4 show improved skill particularly for regions whose winter precipitation and temperature exhibit significant correlation with Nino3.4. Analyses of weights also show that the proposed multimodel combination methodology assigns higher weights for GCMs and lesser weights for climatology during El Nino and La Nina conditions. On the other hand, due to the limited skill of GCMs during neutral conditions over the tropical Pacific, the methodology assigns higher weights for climatology resulting in improved skill from the multimodel combinations. Thus, analyzing GCMsâ skill contingent on the relevant predictor state provide an alternate approach for multimodel combination such that years with limited skill could be replaced with climatology.
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Cropper, Michael Evan. "Analytical and Experimental Investigation of the Damping Matrix in Shear Building Models." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-03282006-113719/.
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In this thesis, we present a study conducted on investigating the nature of damping matrix associated with multi degree of freedom simple shear building models. The various conventional methods of creating damping matrices in structures are summarized and numerical examples are used to illustrate the inconsistencies among them. Numerical examples are also used to illustrate the significance of non-zero off diagonal terms in the transformed damping matrix obtained after pre and post multiplication with mode shape matrix, i.e. the significance of non-classical nature of damping matrix in certain cases. The analytical study is followed by the description of a laboratory experiment that is developed to evaluate the validity of analytical results. The results from experimental studies of simple 2-DOF and 3-DOF shear building models, both with and without supplemental damping devices, are presented to validate the inconsistencies associated with the conventional methods of creating damping matrices in structures. It is also shown that the incorrect formulation of damping matrix results in highly incorrect responses. Several formulations for damping matrices are then proposed and their validity is evaluated by comparison with experimental results.
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Reynolds, William Leonard. "Sustainable Service Rate Analysis at Signalized Intersections with Short Left Turn Pockets Using Macroscopic Simulation." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-03302010-171706/.
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A macroscopic simulation tool is developed and tested in order to quantify the effects of short turn pockets on the sustainable service rate of a signalized intersection. Unlike the theoretical signal capacity, the sustainable service rate includes queue interaction effects and is thus influenced by blockage and spillback at the entrance to a short turn pocket. Previous research on the topic has focused either on the probability of spillback from a short turn pocket or the operation of a system with a single approach lane. No macroscopic model currently available has the ability to analyze throughput reductions due to short turn pocket effects on a multilane approach. The model described herein utilizes a series of flow and density restrictions on cells of varying sizes on the approach to the intersection. Results indicate sensitivity of the model to turn pocket spillback, blockage, saturation flow rate, pocket length, lane utilization, phase sequence, phase overlap, permitted phasing, and time-dependent demand. A phase optimization procedure is also described to help efficiently allocate green time for a given set of turn pocket lengths and turn movement percentages. Outputs from the model compare favorably to results generated using microsimulation software, and recommendations are made regarding additional model enhancements and testing needs.
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Fisher, Seth T. "Development of a Simplified Procedure to Predict Dead Load Deflections of Skewed and Non-Skewed Steel Plate Girder Bridges." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-04082006-092019/.
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Many of today?s steel bridges are being constructed with longer spans and higher skew. As a result, the North Carolina Department of Transportation (NCDOT) has experienced numerous problems in predicting the dead load deflections of steel plate girder bridges. In response to these problems, the NCDOT has funded this research project (Project Number 2004-14). Common dead load deflection prediction methods, which traditionally utilize single girder line (SGL) analysis, have been shown to over predict the dead load deflections; the inaccuracy can result in various costly construction delays and maintenance and safety issues. The primary objective of this research is to develop a simplified procedure to predict dead load deflections of skewed and non-skewed steel plate girder bridges. In developing the simplified procedure, ten steel plate girder bridges were monitored during placement of the concrete deck to observe the deflection of the girders. Detailed three-dimensional finite element models of the bridge structures were generated in the commercially available finite element analysis program ANSYS, and correlations were made between the simulated deflections and the field measured deflections. With confidence in the ability of the developed finite element models to capture bridge deflection behavior, a preprocessor program was written to automate the finite element generation. Subsequently, a parametric study was conducted to investigate the effect of skew angle, girder spacing, span length, cross frame stiffness, number of girders within the span, and exterior to interior girder load ratio on the girder deflection behavior. The results from the parametric were used to develop a simplified procedure, which modifies traditional SGL predictions with empirical equations to account for skew angle, girder spacing, span length, and exterior to interior girder load ratio. Predictions of the deflections from the simplified procedure and from SGL analyses were compared to the deflections predicted from finite element models (ANSYS) and the field measured deflections to validate the procedure. It was concluded that the simplified procedure may be utilized to predict dead load deflections for simple span, steel plate girder bridges. Additionally, an alternative prediction method has been proposed to predict deflections in continuous span, steel plate girder bridges with equal exterior girder loads, and supplementary comparisons were made to validate this method.
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Liu, Li. "Real-time Contaminant Source Characterization in Water Distribution Systems." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-04122009-193753/.
Full textAbstract:
Accidental/intentional contamination continues to be a major concern for the security management in water distribution systems. Once a contaminant has been initially detected, an effective algorithm is required to recover the characteristics of the contaminantâs source based on dynamically varying streams of sensor observations. This dissertation focuses on the development and demonstration of a new algorithm to characterize a contaminant source quickly, accurately, and robustly. An evolutionary algorithm (EA)-based adaptive dynamic optimization technique (ADOPT) is proposed, potentially providing a real-time response. In addition to offering adaptive capacity in a dynamic environment, this algorithm is able to assess the degree of non-uniqueness in the solution through multi-population scheme. This approach, however, requires a large number of time-consuming simulation runs to evaluate possible solutions, and it may be difficult to converge on the best solution or a set of alternative solutions within a reasonable computational time. For this reason, it is desirable to appropriately reduce the decision space over which the optimization procedure must search to reduce the computational burden and to produce faster convergence. A logistic regression-based prescreening technique is investigated in order to reduce the decision space by estimating the probability of a node being a contaminant source location. When a small set of potential source nodes are identified, applying the local search procedure to this set of locations is computationally efficient and potentially good at identifying the best solution. The EA-based ADOPT is then integrated with a logistic regression analysis and a local improvement method to expedite the convergence and to solve the problem potentially faster. The effectiveness of the proposed methods is demonstrated for contamination source identification problems in two illustrative water distribution networks.
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Lunn, Dillon Stewart. "Behavior of Infill Masonry Walls Strengthened with FRP Materials." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-04282009-143603/.
Full textAbstract:
Collapse of unreinforced masonry (URM) structures, including infill walls, is a leading cause of property damage and loss of life during extreme loading events. Many existing structures are in need of retrofit to bring them in compliance with modern design code provisions. Conventional strengthening techniques are often time-consuming, costly, and add significant weight to the structure. These limitations have driven the development of alternatives such as externally bonded (EB) glass fiber reinforced polymer (GFRP) strengthening systems, which are not only lightweight, but can be rapidly applied and do not require prolonged evacuation of the structure. The objective of this research program was to evaluate the effectiveness of strengthening infill masonry walls with externally bonded GFRP sheets to increase their out-of-plane resistance to loading. The experimental program comprises fourteen full-scale specimens, including four un-strengthened (control) specimens and ten strengthened specimens. All specimens consisted of a reinforced concrete (RC) frame (which simulates the supporting RC elements of a building superstructure) that was in-filled with solid concrete brick masonry. The specimens were loaded by out-of-plane uniformly distributed pressure in cycles up to failure. Parameters investigated include the aspect ratio, the strengthening ratio, the number of wythes, and the type of FRP anchorage used. The type of FRP anchorage was found to greatly influence the failure mode. Un-strengthened specimens failed in flexure. However, strengthened specimens without overlap of the FRP onto the RC frame failed due to sliding shear along the bed joints which allowed the walls to push out from the RC frames in a rigid body fashion. In the case where GFRP sheets were overlapped onto the RC frames, the aforementioned sliding shear caused delamination of the GFRP sheets from the RC frames. Use of steel angles anchored along the perimeter of the walls as shear restraints allowed these walls to achieve three times the service load without any visible signs of distress. GFRP strengthening of infill masonry walls was found to be effective, provided that proper anchorage of the FRP laminate was assured.
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Cowie, Stephen James. "Emission of Non-methane Organic Compounds (NMOCs) and Hazardous Air Pollutants (HAPs) from Decomposing Refuse and Individual Waste Components and Under Different Conditions." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-05032004-150500/.
Full textAbstract:
Lab scale reactors were used to measure the emissions of non-methane organic compounds (NMOCs)and hazardous air pollutants (HAPs) from decomposing refuse. Reactors containing municipal solid waste (MSW) as well as reactors containing individual waste components (paper waste, yard waste, food waste, household hazardous waste) were operated under anaerobic conditions with leachate neutralization and recycle. Decomposition of MSW under aerobic and nitrate-reducing conditions was also studied. NMOC yields ranged from 0.016 mg-C/dry gm (paper) to 0.347 mg-C/dry gm (food). The data suggest that volatilization, or air stripping, is the primary mechanism of NMOC release, although the decomposition process also contributes.
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Wylie, John Curtis. "Experimental Testing of Unreinforced Masonry Walls Strengthened with Orthogonal Near-Surface Mounted CFRP Subjected to Out-of-Plane Loading." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-05122009-152004/.
Full textAbstract:
Unreinforced masonry (URM) structures comprise a considerable proportion of the building stock worldwide. However, these structures generally do not behave well under extreme wind or earthquake loading. As part of on-going research, methods of repairing or strengthening URM walls subject to out-of-plane loading using fiber-reinforced polymers (FRP) are being investigated. For several reasons, one method showing particular promise is the use of near-surface mounted (NSM) Carbon FRP strips. Research to-date has made significant progress in quantifying the fundamental behavior of the bonded FRP-to-masonry interface and the behavior of URM walls repaired with vertical FRP strips subject to out-of-plane loading. This thesis presents the experimental results of five large-scale clay brick masonry walls strengthened using NSM CFRP strips and loaded out-of-plane statically to failure using an airbag system. Vertical and Horizontal NSM configurations were tested separately as well as orthogonal grid configurations constructed using two different techniques. The experimentally observed failure mechanisms are described in detail for each wall.
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Hopkins, Daniel Cory. "Characterizing the Spatial Variation in Particle Aggregation due to Heterogeneous Turbulence in a Flocculation Reactor." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-06132002-125938/.
Full textAbstract:
A study was performed to investigate the impact of turbulent heterogeneity on aggregation and breakup in a flocculation reactor. The influence of the average characteristic velocity gradient (G), particle concentration, and coagulation mechanism on the flocculation performance was also investigated. Experiments were performed in a bench-scale reactor with a low-shear axial-flow impeller using a photometric dispersion analyzer (PDA) to examine the state of aggregation. Results indicated that floc growth increased while the floc size and variance in the floc size distribution decreased as G increased. In addition, floc growth, size, and floc size variance increased when the particle concentration of the water was increased and when moving from a charge neutralization mechanism to a sweep floc mechanism. Lastly, floc growth, size, and variance were found to vary spatially at low G values in the reactor with floc size and growth larger in the bulk region and the variance larger in the impeller discharge region.