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1
Limbachiya, Mukeshchandra K. "Assessment of the long term performance of repaired reinforced concrete." Thesis, Sheffield Hallam University, 1995. http://shura.shu.ac.uk/19962/.
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Rational decisions about cost-effective maintenance and structural repair are hampered by the absence of comprehensive data on structural performance of generic repair materials acting compositely with deteriorated concrete elements. In the present climate of durability problems in concrete construction such information is of critical importance. In order to assess long-term structural performance of repaired elements, basic short and long-term properties of generic repair materials are required under various exposure conditions. The principle requirements to ensure satisfactory long-term performance of the repair have always been high dimensional stability and relatively high early bond strength of the repair material with the substrate concrete. As part of a "Brite Euram" project, sponsored by E.E.C., the author has obtained considerable experimental data on properties of three commercially available generic repair materials, which are significant to the subsequent structural behaviour of repaired concrete members. A comparison is also made between the performance of these repair materials with a plain concrete mix of similar strength and stiffness. The following generic repair materials were used: a high performance non-shrinkable concrete, a mineral based cementitious material with no additives and no coarse aggregate size particles, and a cementitious mortar which contains styrene acrylic copolymer with fibre additives. The repair materials are supplied as single component systems by their manufacturers, ready for on-site mixing and use, and require only the addition of clean water. Data on strength, stiffness, post peak-load ductility under compression, swelling, shrinkage and creep deformations under various curing conditions are presented in this thesis. In addition water permeability coefficients and chloride penetration profiles of the materials at various ages of exposure have been determined. A comprehensive compilation of chloride diffusion data is made and an empirical expression is derived for the prediction of long-term chloride penetration profiles based on data obtained at relatively early ages. Application of this prediction model to the field data of some Arabian Gulf structures is made. The influence of repair materials on the performance of reinforced concrete compression members has been studied. A theoretical model is also derived to predict the long-term structural interaction between a repair patch and substrate concrete in short compression members of reinforced concrete. The model is based on the basic properties of materials, such as creep deformation, drying shrinkage and modulus of elasticity. The validity of the model is established on the basis of the experimental data obtained in this study. At the end of the thesis, conclusions and recommendations for future research are made.
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Webb, Graham Thomas. "Structural health monitoring of bridges." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708027.
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Koh, Yeow Leung 1976. "In-situ structural health monitoring of composite repair patches." Monash University, Dept. of Mechanical Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7698.
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Moodi, Faramarz. "Development of a knowledge-based system for the repair and maintenance of concrete structures." Thesis, University of Newcastle Upon Tyne, 2001. http://hdl.handle.net/10443/481.
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Information Technology (IT) can exploit strategic opportunities for new ways of facilitating information and data exchange and the exchange of expert and specialist opinions in any field of engineering. Knowledge-Based Systems are sophisticated computer programs which store expert knowledge on specific subject and are applied to a broad range of engineering problems. Integrated Database applications have facilitated the essential capability of storing data to overcome an increasing information malaise. Integrating these areas of Information Technology (IT) can be used to bring a group of experts in any field of engineering closer together by allowing them to communicate and exchange information and opinions. The central feature of this research study is the integration of these hitherto separate areas of Information Technology (IT). In this thesis an adaptable Graphic User Interface Centred application comprising a Knowledge-Based Expert System (DEMARECEXPERT), a Database Management System (REPCON) and Evaluation program (ECON) alongside visualisation technologies is developed to produce an innovative platform which will facilitate and encourage the development of knowledge in concrete repair. Diagnosis, Evaluation, MAintenance and REpair of Concrete structures (DEMAREC) is a flexible application which can be used in four modes of Education, Diagnostic, Evaluation and Evolution. In the educational mode an inexperienced user can develop a better understanding of the repair of concrete technology by navigating through a database of textual and pictorial data. In the diagnostic mode, pictures and descriptive information taken from the database and performance of the expert system (DEMAREC-EXPERT) are used in a way that makes problem solving and decision making easier. The DEMAREC-EXPERT system is coupled to the REPCON (as an independent database) in order to provide the user with recommendations related to the best course required for maintenance and in the selection of materials and methods for the repair of concrete. In the evaluation mode the conditions observed are described in unambiguous terms that can be used by the user to be able to take engineering and management actions for the repair and maintenance of the structure. In the evolution mode of the application, the nature of distress, repair and maintenance of concrete structures within the extent of the database management system has been assessedT. he new methodology of data/usere valuation could have wider implications in many knowledge rich areas of expertise. The benefit of using REPCON lies in the enhanced levels of confidence which can be attributed to the data and to contribution of that data. Effectively, REPCON is designed to model a true evolution of a field of expertise but allows that expertise to move on in faster and more structured manner. This research has wider implications than within the realm of concrete repair. The methodology described in this thesis is developed to provide tecýnology transfer of information from experts, specialists to other practitioners and vice versa and it provides a common forum for communication and exchange information between them. Indeed, one of the strengths of the system is the way in which it allows the promotion and relegation of knowledge according to the opinion of users of different levels of ability from expert to novice. It creates a flexible environment in which an inexperienced user can develop his knowledge in maintenance and concrete repair structures. It is explained how an expert and a specialist can contribute his experience and knowledge towards improving and evolving the problem solving capability of the application.
5
Parker, James M. "Structural studies of two proteins involved in the maintenance of genomic stability, FEN 1 and DNA-PKcs." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/21709.
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Genomic stability refers to an organism’s ability to maintain and pass forward its genetic information. There are a raft of proteins and pathways whose sole purpose is maintaining this stability through swiftly replicating DNA as well as accurately repairing damage caused through contact with endogenous and exogenous DNA damaging elements. This study will focus on the structural aspects of two proteins that play a part in different areas of genome maintenance. Flap Endonuclease 1 (FEN 1) works in DNA replication, where it is tasked with removing a small RNA flap that is created during Okazaki fragment formation. This flap removal is essential to mature these fragments into one continuous strand of nascent DNA. Using the archeon Pyrococcus abyssi (Pab) as a model system has the advantage of possessing simple replicative machinery, whilst bearing striking similarities with the human system. Pab is a hyperthermophilic, piezophile meaning it thrives in conditions of high temperature and pressure. DNA-dependent protein kinase (DNA-PK) is a holoenzyme that plays a role in the Non Homologous End Joining (NHEJ) pathway by repairing DNA double strand breaks (DSB’s). In cancer therapy, a patient is exposed to DNA damaging elements, leading to an ever-increasing population of DSBs. If an inhibitor of DNA-PKcs were introduced along with this therapy it could potentiate its effect, as the cancerous cells will be less able to repair the damage. The aim of this part of the study is to determine a protocol to generate pure, soluble, correctly folded protein for the purposes of biophysical characterisation and X-ray crystallographic structural studies.
6
Chan, Fan, and 陳帆. "Structural and cultural change in a government service under commercialisation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31266344.
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Doherty, Kevin Thomas. "An investigation of the weak links in the seismic load path of unreinforced masonary buildings /." Title page, table of contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phd655.pdf.
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Thaesler-Garibaldi, Maria P. "A methodology to Develop an Integrated Engineering System to Estimate Quantities for Bridge Repairs at the Pre-Design Stage." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6915.
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A Damage Assessment Model, Construction Process Model and Parametric Quantity Model were developed with the purpose of capturing the engineering knowledge involved in the estimating process of bridge repair construction projects.
The Damage Assessment Model was used to create a sample database in which detailed inspection data was stored in a format compatible with the existing Pontis?tabase. Detailed inspection data, which provided quantitative values for the different damage types observed in bridges, could be retrieved from the sample database so that data could be used as either input parameters in the knowledge rules that triggered the selection of construction tasks in the Construction Process Model, or data could be used as variables in the equations used to estimate quantities in the Parametric Quantity Model.
The Construction Process Model was used to incorporate the logic behind the construction process for different repair methods. The Construction Process Model was composed of seven repair matrices that defined specific repair methods for each Pontis?idge element. Construction tasks were grouped in construction modules that were modeled as flowcharts. Each construction module flowchart was composed of construction tasks arranged in sequential order and decision points that triggered the selection of construction tasks based on input parameters and knowledge rules. Input parameters were provided by the user, retrieved from the model or pre-defined in the model by expert knowledge. The construction modules developed involved construction tasks related to the repair of concrete bridge piles that were damaged due to reinforcement corrosion and related concrete deterioration. Data describing the construction tasks that were considered in the construction module flowcharts were modeled using the entity-relationship model and were stored in the sample database described previously.
The Parametric Quantity Model combined data generated by the Damage Assessment Model and the Construction Process Model with additional expert knowledge and parameters into equations that were used to estimate quantities.
The author investigated the use of neural networks as a tool to predict actual damage in bridge piles, conducted a preliminary survey to define labor productivity factors and collected data to define the duration of construction activities related to bridge repair.
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Lopes, Luis Antonio Rodrigues. "Sistemas inteligentes aplicados em monitoramento de estruturas aeronáuticas." Universidade do Estado do Rio de Janeiro, 2013. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7446.
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Este trabalho apresenta o desenvolvimento de sistemas inteligentes aplicados ao
monitoramento de estruturas aeronáuticas abordando dois modelos distintos: o primeiro é a
análise e classificação de imagens de ultrassom de estruturas aeronáuticas com objetivo de
apoiar decisões em reparo de estruturas aeronáuticas. Foi definido como escopo do trabalho
uma seção transversal da asa da aeronave modelo Boeing 707. Após a remoção de material
superficial em áreas comprometidas por corrosão, é realizada a medição da espessura ao
longo da área da peça. Com base nestas medições, a Engenharia realiza a análise estrutural,
observando os limites determinados pelo manual de manutenção e determina a necessidade ou
não de reparo. O segundo modelo compreende o método de impedância eletromecânica. É
proposto o desenvolvimento de um sistema de monitoramento de baixo custo aplicado em
uma barra de alumínio aeronáutico com 10 posições de fixação de porcas e parafusos. O
objetivo do sistema é avaliar, a partir das curvas de impedância extraídas do transdutor PZT
fixado na barra, sua capacidade de classificar a existência ou não de um dano na estrutura e,
em caso de existência do dano, indicar sua localização e seu grau de severidade. Foram
utilizados os seguintes classificadores neste trabalho: máquina de vetor de suporte, redes
neurais artificiais e K vizinhos mais próximos.This work presents the development of intelligent systems applied to the monitoring of aircraft structures addressing two distinct models: the first is the analysis and classification of ultrasound images of aircraft structures in order to support decisions on repair of aircraft structures. A scope of work was defined as a cross section of the wing of the aircraft model Boeing 707. After the removal of surface material in damaged areas by corrosion, thickness measurements in the whole structure are evaluated. Based on the measurements, the Engineering performs structural analysis, observing the limits determined by the maintenance manual and determining the necessity of repair. The second model includes the method of electromechanical impedance. It is proposed to develop a low cost monitoring system applied to an aircraft aluminum bar with 10 positions for fixing nuts and bolts. The goal of the system is to classify an impedance curve in the condition of the aluminum bar if there is or not a damage to the structure and, in case of the existence of damage, indicating their position in the aluminum bar and if the damage is severe or not. The following classifiers were used in this work: support vector machine, artificial neural networks and K nearest neighbors.
10
Krapf, Carlyn Nicole. "Stress relaxation of stainless steel rods for bridge pier cap shear strengthening." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33859.
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This thesis examines the stress relaxation phenomenon that may occur in stainless steel rods that are used as part of an all-stainless steel externally post-tensioned rod system for strengthening reinforced concrete pier caps in shear. An overview of the stress relaxation phenomenon and its modeling is presented. Previous work on stress relaxation of stainless steel is reviewed and used to select an appropriate stress relaxation model to analyze the stress relaxation data obtained from experiments performed during this research. An experimental program utilizing six specimens of Type 304/304L stainless steel stainless steel rods similar to those likely to be candidates for pier cap rehabilitation is presented, and the data are analyzed using the model identified from the review. This model reasonably captures the behavior of the resulting stress relaxation with time, and calculates stress values that are fairly close to those obtained experimentally. Using this model to predict long-term stress losses in a service environment, guidelines for design and installation of the post-tensioned stainless steel rods are proposed.
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Benoist, Camille. "Intégration fonctionnelle du complexe SMC chez bacillus subtilis : étude de suppresseurs." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112268.
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Les protéines de type SMC (pour « Structural Maintenance of Chromosomes ») sont impliquées dans différents aspects de la dynamique du chromosome tels que la condensation, la ségrégation et la réparation de l’ADN. En effet, une souche de Bacillus subtilis dépourvue de SMC présente des phénotypes sévères tels qu’un défaut dans la compaction et le partitionnement du chromosome, une sensibilité accrue à certaines drogues endommageant l’ADN ainsi qu’à des inhibiteurs de gyrase. Une telle souche est incapable de croître en condition de croissance rapide. Pour comprendre l’étendue des phénotypes associés à la perte de ce gène, une identification génétique de nouveaux partenaires a été entreprise : des suppresseurs spontanés de la délétion de smc ont été isolés en condition de croissance rapide. Différentes classes de suppresseurs ont été mises en évidence, suggérant que différentes mutations pouvaient restaurer la viabilité d’une souche dépourvue de SMC. Leur caractérisation a révélé qu'ils permettaient de restaurer une partie des défauts que présente le mutant Δsmc, en particulier la résistance aux inhibiteurs de gyrase, et semblaient limiter la formation de cassures de l'ADN. Par séquençage du génome complet des suppresseurs, certaines de ces mutations ont pu être identifiées, et semblent causer une perturbation de la voie de biosynthèse des ARN de transfert. Cette perturbation permet de restaurer le défaut de croissance, et ce plus efficacement qu’une inhibition de la traduction par des drogues comme le chloramphénicol, ou par la réduction du pool de nucléotides par l’hydroxyurée. L’ensemble de ces résultats suggère que la réponse stringente pourrait être en partie responsable du phénotype suppresseur. Il est proposé qu’en dehors de la compaction du chromosome, le complexe SMC soit directement impliqué dans le maintien de l’intégrité des fourches de réplicationSMC proteins (for "Structural Maintenance of Chromosomes") are involved in different aspects of chromosome dynamic such as condensation, segregation and DNA repair. Indeed, a Bacillus subtilis mutant lacking the SMC complex shows severe phenotypes such as defects in condensation and chromosome partitioning, an increase in sensitivity DNA damaging drugs or gyrase inhibitors. The viability of such strain is limited to conditions of slow growth. To understand the range of phenotypes associated with loss of this gene, a genetic identification of new partners was undertaken: spontaneous suppressors of smc deletion were isolated in rapid growth conditions. Different classes of suppressors have been identified, suggesting that different mutations could restore the viability of a strain lacking SMC complex. Characterization of suppressors revealed they can restore some of the defects shown in Δsmc mutant, particularly resistance to gyrase inhibitors, and seemed to limit the formation of DNA breaks. By sequencing the complete genome of suppressors, some of these mutations have been identified and cause an alteration of the biosynthetic pathway of transfer RNA. This disruption can restore the growth defect more efficiently than inhibition of translation by drugs such as chloramphenicol, or by reducing the pool of nucleotides by hydroxyurea. Taken together, these results suggest that the stringent response could be partly responsible for the suppressor phenotype. It is proposed that apart from the compaction of the chromosome, the SMC complex is directly involved in maintaining the integrity of replication forks
12
Lemos, Sérgio Pereira Pinto. "Avaliação do grau do dano das estruturas do subsolo de três edifícios situados na Região Metropolitana do Recife." Universidade Católica de Pernambuco, 2006. http://www.unicap.br/tede//tde_busca/arquivo.php?codArquivo=29.
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Procurando conhecer o grau de deterioração precoce das estruturas de concreto armado dos edifícios residenciais da Região Metropolitana da Cidade do Recife, Estado de Pernambuco, este trabalho visa, utilizando um método de quantificação dos danos e o uso de ensaios, avaliar as patologias das estruturas estudadas. Estudou-se três edifícios residenciais (ER), com semelhante padrão de construção, idades construtivas aproximadas e inseridos em diferentes classes de agressividade ambiental. Foi realizada inspeção visual e ensaios em amostras dos pilares, vigas, lajes e reservatório inferior do subsolo dos três edifícios. Após análise dos três edifícios, verificou-se que o caso ER 1, localizado em classe ambiental de agressividade forte (III), a mais agredida pelo meio ambiente, e o estudo de caso ER 2, localizado a uma distância significativa da orla marinha em Classe de Agressividade Ambiental II, apresentaram grau de deterioração media (GD) de 36,98 e 31,23 respectivamente, com recomendação para inspeção periódica e intervenção a médio prazo. Já o estudo de caso ER 3, que está localizado dentro da uma classe de agressividade forte (III), em orla marinha, porém com barreiras de proteção que evitam a incidência direta da névoa salina, encontra-se com alto grau de deterioração (GD = 103,94), sugerindo uma intervenção imediata com riscos de colapsoThis work aims to evaluate the pathology of residential buildings structures located at the Metropolitan Region of Recife, Brazil using the quantification of damages to measure the degree of early deterioration of reinforced concrete. Three residential buildings (RB) with similar construction standards were studied. All buildings have approximate age and are inserted into environmental aggressiveness distinct. A visual inspection took place as well as a laboratorial sample analysis of their pillars, beams and underground water reservatories. It was verified that the RB1 case, located at a high environmental aggressiveness class (III), and the RB2 case, located significatively far from the sea and classified with a moderate environmental aggressiveness class (II), both presented a medium degree of deterioration (GDE). For both buildings it is suggested a periodic inspection recommendation and a medium term intervention (GD 1 = 36,98 ; GD 2 = 31,23). The third case (RB3), located at a high environmental aggressiveness class (III) and seafront with protection barriers, presented a high degree of deterioration (GD 3=103,94). It is suggested for RB3 an immediate intervention with collapse risks
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蔡玉寧 and Yuk-ning Alta Choi. "Repair technology for cracked metallic structures using composite materials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222420.
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Lai, Tsan-kei, and 黎贊基. "Condition auditing and repair of marine concrete structures in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B43894550.
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Kannappan, Laxmikant Aerospace Civil & Mechanical Engineering Australian Defence Force Academy UNSW. "Damage detection in structures using natural frequency measurements." Awarded by:University of New South Wales - Australian Defence Force Academy. Aerospace, Civil & Mechanical Engineering, 2009. http://handle.unsw.edu.au/1959.4/44852.
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In the last two decades, the emphasis in aircraft maintenance has been on developing online structural health monitoring systems to replace conventional non destructive inspection techniques which require considerable down-time, human effort and cost. Vibration based damage detection is one of the most promising techniques for implementation in Structural Health Monitoring (SHM). In vibration based methods, the presence of damage is detected by monitoring changes in one of the dynamic parameters of the structure, resonant frequencies, modeshapes or damping characteristics. Compared to modeshape based methods, frequency based methods have the advantage that measurements need to be taken only at a single location. Previous developments on frequency based techniques have relied on Finite Element Model updating; analytical techniques have hitherto been restricted to beams due to the complexity in developing equations for cracked two dimensional structures. In this thesis the analytical approach using an energy formulation is extended to plates with through-thickness cracks, where modeshapes from either numerical modelling or experimental measurements can be employed to determine the energy of vibration. It is demonstrated that by using a hybrid approach, incorporating experimentally measured modeshapes along with measured changes in frequencies, the damage parameters can be estimated without resorting to theoretical modelling or numerical analysis. The inverse problem of finding the crack location, size and orientation from measured changes in frequencies is addressed using minimisation techniques. The forward problem and the inverse algorithm is first validated using numerical simulation and experimental testing of beams with edge cracks and centre cracks. The application of the methodology to the two dimensional case is then validated by numerical simulation and experimental modal analysis of plates with through thickness cracks. A statistical procedure is developed for determination of the 90/95 probability of crack detection and the minimum detectable crack size in both cases. It is demonstrated that the measurement of frequency changes can be successfully employed to detect and assess the location and size of cracks in beams and plates, using modeshapes from theory, Finite Element Analysis.
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Elwany, Alaa H. "Sensor-based prognostics and structured maintenance policies for components with complex degradation." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37198.
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We propose a mathematical framework that integrates low-level sensory signals from monitoring engineering systems and their components with high-level decision models for maintenance optimization. Our objective is to derive optimal adaptive maintenance strategies that capitalize on condition monitoring information to update maintenance actions based upon the current state of health of the system. We refer to this sensor-based decision methodology as "sense-and-respond logistics".
As a first step, we develop and extend degradation models to compute and periodically update the remaining life distribution of fielded components using in situ degradation signals. Next, we integrate these sensory updated remaining life distributions with maintenance decision models to; (1) determine, in real-time, the optimal time to replace a component such that the lost opportunity costs due to early replacements are minimized and system utilization is increased, and (2) sequentially determine the optimal time to order a spare part such that inventory holding costs are minimized while preventing stock outs.
Lastly, we integrate the proposed degradation model with Markov process models to derive structured replacement and spare parts ordering policies. In particular, we show that the optimal maintenance policy for our problem setting is a monotonically non-decreasing control limit type policy. We validate our methodology using real-world data from monitoring a piece of rotating machinery using vibration accelerometers. We also demonstrate that the proposed sense-and-respond decision methodology results in better decisions and reduced costs compared to other traditional approaches.
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Baran, Mehmet. "Precast Concrete Panel Reinforced Infill Walls For Seismic Strengthening Of Reinforced Concrete Framed Structures." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606137/index.pdf.
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The importance of seismic rehabilitation became evident with 1992 Erzincan Earthquake, after which a large number of reinforced concrete buildings damaged in recent earthquakes required strengthening as well as repair. In the studies related
to rehabilitation, it has been realized that inadequate lateral stiffness is one of the major causes of damage in reinforced concrete buildings. Recently, economical, structurally effective and practically applicable seismic retrofitting techniques are being developed in METU Structural Mechanics Laboratory to overcome these kinds of problems.
The strengthening technique proposed in this thesis is on the basis of the principle of strengthening the existing hollow brick infill walls by using high strength precast concrete panels such that they act as cast-in-place concrete infills
improving the lateral stiffness. Also, the technique would not require evacuation of the building and would be applicable without causing too much disturbance to the occupant. For this purpose, after two preliminary tests to verify the proper
functioning of the newly developed test set-up, a total of fourteen one-bay two story reinforced concrete frames with hollow brick infill wall, two being unstrengthened reference frames, were tested under reversed cyclic lateral loading
simulating earthquake loading. The specimens were strengthened by using six different types of precast concrete panels. Strength, stiffness, energy dissipation and story drift characteristics of the specimens were examined by evaluating the test results. Test results indicated that the proposed seismic strengthening technique can be very effective in improving the seismic performance of the reinforced
concrete framed building structures commonly used in Turkey.
In the analytical part of the study, hollow brick infill walls strengthened by using high strength precast concrete panels were modelled once by means of equivalent
diagonal struts and once as monolithic walls having an equivalent thickness. The experimental results were compared with the analytical results of the two approaches mentioned. On the basis of the analytical work, practical recommendations were made for the design of such strengthening intervention to be executed in actual practice.
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Madonsela, Alex Thulani. "A structured approach for the reduction of mean time to repair of blast furnace D, ArcelorMittal, South Africa, Vanderbijlpark / Madonsela A.T." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7311.
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Organizations are expected by their shareholders to continually deliver above
industry returns on capital invested and to remain competitive in the industry of
choice through productivity, safety and quality. The maintenance function is a key
area in which competitiveness through efficiencies and world–class performance can
be attained by focusing on the prevention and reduction of long and costly
equipment repair times.
The question is: how can the mean time to repair of equipment already installed in
the plant be reduced?
To answer the above question correctly and comprehensively, the research explored
mixed methods in finding answers. Quantitative methodology using a survey was
used for data collection. Observations and interviews were held with maintenance
personnel to uncover information that couldn’t have been obtained by means of a
survey.
The survey was limited to equipment performance measures, human factors,
environmental factors, planning, spare parts, maintainability, procedures and
training. To test consistency and accuracy of representation of the total population
under study, a reliability test was done by using Cronbach’s alpha coefficient. To
determine whether there are any differences between groups, an ANOVA test was
used. Cohen’s d–value was used to determine practically significant differences
between one set of data with another and correlation analysis was used to determine
the relationships between the variables.
The approach designed and delivered by this research flowed from the existing body
of knowledge, case studies and survey findings. The approach adopts some of the
elements of the failure mode and effects analysis (FMEA) procedure and differs from
other work that has been done by others by taking into account the competency and
experience of maintenance personnel and assigning to them factors which are used
to compute anew MTTR of the equipment. The cost of implementing the
recommended corrective actions for realising the new MTTR is determined and
evaluated against an improved equipment availability that will be achieved as a
result of the recommended corrective actions assuming that the failure rate of the
equipment remains constant. This evaluation step imbedded within the approach is
valuable for the maintenance function and management for decision making in
ensuring that resources at the organization’s disposal are used productively.
Validation and test results of the approach showed that the MTTR of equipment
installed in the plant can be reduced. The results also indicated that through the use
of the designed approach a regular pattern of repair or replacement times can be
followed well in advance and that it is practical, user friendly and it also delivers on
its objective of offering a structure for analysis and decision making aimed at
reducing the MTTR.
Included with this dissertation is feedback information that can be included in a
maintenance job card feedback section to capture information about factors that can
be improved to lower the MTTR as part of a continuous improvement process.
Included also is a spare part development and management procedure that can be
used by the maintenance function.
Recommendations on training of maintenance personnel on the maintainability of
equipment, the FMEA procedure and maintenance procedures are highlighted.
Information that flowed from this approach will be valuable for continuous plant
performance improvement and during the design, installation and operation stages of a blast furnace.Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2012.
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Rohem, Ney Robson Ferreira. "Desenvolvimento de sistema de reparo para dutos e tubulações industriais utilizando materiais compósitos de matriz polimérica." Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1597.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorO emprego de materiais compósitos de matriz polimérica como reparo e reforço em estruturas nas indústrias do petróleo tem se tornado uma prática industrial comum. O uso destes reforços compreende desde o recobrimento de superfícies com defeitos, passantes ou não, até o reforço estrutural. Na última década, muitos estudos foram feitos para o desenvolvimento de uma metodologia alternativa para reforço e reparo de dutos com materiais compósitos. Recentemente, em 2006, o sistema ISO de normas técnicas apresentou a primeira especificação técnica de "Reparo em Compósitos para dutos das indústrias de Petróleo, Petroquímica e de Gás Natural Qualificação, projeto, instalação, testes e inspeção" ISO/PDTS 24817. O presente trabalho tem como objetivo o desenvolvimento de um sistema de reparo, utilizando materiais compósitos de matriz polimérica para o reparo e reforço estrutural de dutos e tubulações industriais, em conformidade com a Norma ISO 24817:2006. Foram desenvolvidos procedimentos para a confecção de corpos de prova destinados a ensaios mecânicos, e para aplicação do sistema de reparo. O sistema de reparo é destinado a defeitos tais como perda de espessura, amassamentos e danos transpassantes. Foi construída, em paralelo, toda a infraestrutura para a montagem de um laboratório destinado ao estudo de materiais compósitos, no Laboratório de Adesão e Aderência. São apresentados resultados de parte dos ensaios mecânicos necessários, comparação dos resultados obtidos com modelos teóricos e testes hidrostáticos.
The use of polymer matrix composites to repair and strengthen structures in the oil industry has become a common industry practice. The use of these reinforcements extends from covering surfaces with defects, through wall or not, to structural reinforcement. In the last decade, many studies have been done to develop an alternative approach to the strengthening and repairing of pipelines with composite materials. Recently, in 2006, the ISO system of technical standards presented the document technical support "Petroleum, petrochemical and natural gas industries Composite repairs for pipework Qualification, design, installation, testing and inspection" ISO/PDTS 24817. This study aims to develop a repair system using polymer matrix composite materials for repair and reinforcement of piping and pipelines in accordance with ISO 24817:2006. Procedures where developed for the confection of test specimens for mechanical testing, and application of the repair. The system is intended to repair defects such as thickness loss, gouges, and damage through wall or not. In parallel, an entire infrastructure was built for the conception of a laboratory for the study of composite materials at the Laboratory of Adhesion and Adherence. Here are presented the results of the required mechanical tests, the comparison results with theoretical models, and the hydrostatic testing.
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Garcia-Mardambek, Nouar. "Etude d'une stratégie de maintenance adaptative pour des systèmes logiques." Grenoble INPG, 1991. http://www.theses.fr/1991INPG0076.
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La complexité des équipements numériques entraîne une difficulté croissante des tâches de vérification de ces équipements tout au long de leur vie: conception, production, industrialisation et maintenance. Chacune de ces étapes induit des modes de défaillances spécifiques et nécessite des méthodes de vérification adaptées. Alors que des méthodes et outils de génération de test ont été développés pour les étapes de conception et production, les vérifications en phase opérationnelle sont restées très empiriques, et font largement appel à l'expertise des ingénieurs de maintenance. C'est pourquoi nous nous sommes intéressés à la maintenance préventive/curative des systèmes numériques. L'objectif était de concevoir une stratégie qui organise l'exécution de fonctions élémentaires de test en fonction du type de vérification (prévention, correction) et des contraintes à prendre en compte. Cette stratégie fournit une spécification fonctionnelle du programme de maintenance. Le problème rencontré est équivalent à un problème de couverture d'une matrice booléenne. Nous avons proposé et validé: ― des méthodes de résolution classique: multiplication directe, branchement par ligne et par colonne, arbre sémantique; le problème à résoudre est équivalent à un problème de conversion d'une formule normale conjonctive en une formule normale équivalente disjonctive (CFN-DFN). C'est un problème NP-complet. Ces méthodes de résolution fournissent toutes les solutions minimales en minimisant la complexité des algorithmes appliqués et le temps de calcul nécessaire; ― une méthode heuristique fondée sur des techniques d'Intelligence Artificielle: ce type de résolution fournit une solution optimale par rapport à un ensemble de critères donnés. Un certain nombre de systèmes à base de techniques d'I. A. Ayant été développés dans les différents domaines du test: diagnostic, génération des stimuli, maintenance et réparation, nous avons mené une analyse comparative et fait une synthèse sur l'ensemble des solutions de type système expert. Le système OPS5, à base de productions, a été utilisé pour la programmation de ces différentes méthodes, et leur validation sur des cartes réelles
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Mareš, Petr. "Problematika snížení ceny rodinného domu v důsledku vady střešní konstrukce." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-232624.
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This master’s thesis provides us into the issues of reduction of house prices due to roof structure defect. First charter takes interest in theorethical solutions for residential houses valuation with defects.Real estate survey is introduced in chapter two. The third part of this master’s thesis is focused on possible roof structure defects and malfunctions. In last charter we can find the valuation of house with defect. The main goal of this thesis is to create a procedure for the reduction of property price with roof structure defect.
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Výpustek, Libor. "Průzkum a hodnocení mostu na dálnici D2." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225738.
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This thesis deals with the exploration and evaluation of the existing bridge carried him on the highway D2. The work is divided into theoretical and practical parts. The theoretical part focuses on the technical surveys, diagnosis of building structures and some methods of investigation and testing of building structures. In the practical part the visual inspection and diagnosis of disorders of the highway bridge substructures ev. No. D2-058, to determine material characteristics substructure and evaluate the state of the bridge. In conclusion, the practical part of the recommendations for the design and method of repairing the bridge.
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Ševčík, Jaroslav. "Funkční díly v ocenění stavebního objektu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240175.
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Diploma thesis deals with comparing of current awards by Classification of building structures and works and awards by Functional parts. It is possible to calculate Building life cycle costs by Functional parts. This is definately the advantage of the system because the calculation cannot be done by Classification of building structures and works. A new law on public procurement deals with Building life cycle costs as an evaluation criterion. So it is recommended to use Functional parts awards. The other goal of the thesis is to find bridges between Functional parts and the issue of BIM. BIM is a trend of global construction industry.
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Feng, Dongming. "Advanced Vision-Based Displacement Sensors for Structural Health Monitoring." Thesis, 2016. https://doi.org/10.7916/D8C8294G.
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Most existing structural health monitoring (SHM) techniques are based on measured acceleration data. Such practice, however, is highly expensive to operate, mainly due to cumbersome, time-consuming and expensive installation of sensors and their data acquisition systems. As an emerging noncontact method, the vision-based displacement sensor systems have attracted significant research interests and offered a promising alternative to the conventional sensors for SHM. However, most existing vision-based sensors require physical access to the structure to install a predesigned target panel, which has a higher contrast and thus is easier to track. Besides, most studies are carried out in controlled laboratory environments. The accuracy and robustness of vision sensors in the outdoor field conditions have not been fully investigated. It is also noted that current researches are mainly focusing on the measurement performance evaluation of vision sensors, without discussing the use of the measured displacement data for SHM.
This dissertation develops a high-precision vision sensor system for remote and real-time measurement of multipoint structural displacements by tracking natural targets on structural surfaces. Two sets of software packages are developed respectively based on two advanced template matching algorithms (i.e., the upsampled cross correlation and the orientation code matching) incorporated with different subpixel techniques. Comprehensive experiments, including laboratory shaking table tests and field bridge tests, are carried out to evaluate its performance. Satisfactory agreements are observed between the displacements measured by the proposed vision sensor and those measured by high-performance reference displacement sensors. Moreover, this study examines the robustness of the vision sensor against ill environmental conditions such as dim light, background image disturbance and partial template occlusion.
This dissertation further explores the potentials of the vision sensor for fast and inexpensive SHM applications, by demonstrating the usefulness of the displacement data for experimental modal analysis, finite element (FE) model updating, damage detection, etc. For a three-story frame structure, the modal analysis shows that the obtained natural frequencies and mode shapes from displacement measurements by using one camera match well with those by using four accelerometers. In fact, the vision sensor can achieve smoother mode shapes which would make damage localization more accurate, while the resolution of mode shapes from accelerometers is limited by the sensor number. This has been demonstrated from the damage detection result of beam structures based on the mode shape curvature (MSC) index. To address the needs for monitoring aging railway and highway bridges, coupled train-track-bridge and vehicle-bridge FE models are firstly developed to study the dynamic interactions between bridges and moving trains/vehicles. Subsequently, a time-domain model updating approach for railway bridges is proposed based on the in-situ measurement of the bridges’ dynamic displacement histories by the proposed vision sensor. This dissertation further proposes a bridge damage detection procedure that utilizes vehicle-induced displacement response and the MSC index without requiring prior knowledge about the traffic excitation.
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Jang, Jinwoo. "Development of Data Analytics and Modeling Tools for Civil Infrastructure Condition Monitoring Applications." Thesis, 2016. https://doi.org/10.7916/D82N52HN.
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This dissertation focuses on the development of data analytics approaches to two distinct important condition monitoring applications in civil infrastructure: structural health monitoring and road surface monitoring. In the first part, measured vibration responses of a major long-span bridge are used to identify its modal properties. Variations in natural frequencies over a daily cycle have been observed with measured data, which are probably due to environmental effects such as temperature and traffic. With a focus on understanding the relationships between natural frequencies and temperatures, a controlled simulation-based study is conducted with the use of a full-scale finite element (FE) model and four regression models. In addition to the temperature effect study, the identified modal properties and the FE model are used to explore both deterministic and probabilistic model updating approaches. In the deterministic approach (sensitivity-based model updating), the regularization technique is applied to deal with a trade-off between natural frequency and mode shape agreements. Specific nonlinear constraints on mode shape agreements are suggested here. Their capabilities to adjust mode shape agreements are validated with the FE model. To the best of the author's knowledge, the sensitivity-based clustering technique, which enables one to determine efficient updating parameters based on a sensitivity analysis, has not previously been applied to any civil structure. Therefore, this technique is adapted and applied to a full-scale bridge model for the first time to highlight its capability and robustness to select physically meaningful updating parameters based on the sensitivity of natural frequencies with respect to both mass and stiffness-related physical parameters. Efficient and physically meaningful updating parameters are determined by the sensitivity-based clustering technique, resulting in an updated model that has a better agreement with measured data sets. When it comes to the probabilistic approach, the application of Bayesian model updating to large-scale civil structures based on real data is very rare and challenging due to the high level of uncertainties associated with the complexity of a large-scale model and variations in natural frequencies and mode shapes identified from real measured data. In this dissertation, the full-scale FE model is updated via the Bayesian model updating framework in an effort to explore the applicability of Bayesian model updating to a more complex and realistic problem. Uncertainties of updating parameters, uncertainty reductions due to information provided by data sets, and uncertainty propagations to modal properties of the FE model are estimated based on generated posterior samples.
In the second part of this dissertation, a new innovative framework is developed to collect pavement distress data via multiple vehicles. Vehicle vibration responses are used to detect isolated pavement distress and rough road surfaces. GPS positioning data are used to localize identified road conditions. A real-time local data logging algorithm is developed to increase the efficiency of data logging in each vehicle client. Supervised machine learning algorithms are implemented to classify measured dynamic responses into three categories. Since data are collected from multiple vehicles, the trajectory clustering algorithm is introduced to integrate various trajectories to provide a compact format of information about road surface conditions. The suggested framework is tested and evaluated in real road networks.
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Jooste, Fritz Joubert. "Structural classification of granular base pavements using measured deflection bowl parameters." Thesis, 2014. http://hdl.handle.net/10210/10224.
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M.Ing. (Civil Engineering)The: structural classification of granular base pavements by means of resilient deflection bowl parameters measured by the Impulse Deflection Meter and application of measured deflections at network level were investigated. The Investigation consisted of a mechanistic analysis and an analysis of observed field results. Curves for structural classification of granular base pavements obtained by regression are presented. The Curves obtained by the analysis of field observations compare well with local experience and theoretical failure criteria. It was found that the mechanistic model used in this study did not yield satisfactory results when simulating deflection behaviour through linear elastic programs. The parameters recommended for future use are Maximum Deflection (Y-rnax), Base Layer Index, or DLl (formerly SCI), Middle Layer Index, or MLl (formerly DOl) and Radius of Curvature. The use of deflection measurements at network level was also investigated. A method for calculating a Structural Stiffness Index to be incorporated into Pavement Management Systems as a Structural Indicator is proposed. Recommendations regarding the density of testing and identification of roads for testing at network level are also made. Several factors influencing deflections and structural bearing capacity are discussed and some recommendation." are made. The main factors influencing deflections and predicted pavement structural capacity were shown to be Temperature, Seasonal Influences and Condition of Surfacing. Further research into the specific influence of these factors on deflections and hearing capacity is needed.
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Wani, Saima Masood. "Elucidation of the Role of Nse1, a RING Domain Containing Component of Smc5/6 complex, in Maintenance of Chromosome Stability in Saccharomyces cerevisiae." Thesis, 2017. http://etd.iisc.ernet.in/2005/3570.
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Structural Maintenance of Chromosomes (SMC) proteins are a highly conserved class of proteins required for the maintenance of genome stability and regulate nearly all aspects of chromosome biology. Eukaryotes, such as the budding yeast Saccharomyces cerevisiae, have six Smc proteins that form three SMC complexes in association with non-SMC proteins, i.e., the cohesin complex, the condensin complex and the Smc5/6 complex. The yeast Smc5/6 complex consists of Smc5, Smc6 and six non-Smc elements (Nse1-6) that are all essential for the survival of cells.
Nse1 is the first non-smcelement that was identified associated with the Smc5/6 complex. Nse1 has a C-terminal RING-domain, which is a characteristic feature of some E3 ubiquitin ligases. A RING domain consists of eight conserved Zn-coordinating residues arranged in a cross-brace conformation. To understand the importance of this domain, we created site directed mutations in conserved residues identified by sequence alignment of the budding yeast Nse1 RING domain with that of other species. We found a new RING domain mutant nse1-103that was temperature sensitive at 37°C and showed an increased sensitivity towards genotoxic agents such as hydroxyurea (HU), methyl methane sulfonate (MMS) and ultraviolet (UV) radiation. Thense1-103 mutant cells are slow growing and show delayed chromosomal replication at the restrictive temperature. Genetic interactions with replication factors such as RRM3, TOF1 etc. revealed thatnse1-103shows a synthetic sick growth defect in combination with rrm3∆ that is partially suppressed by deletion of TOF1. We found an enhancement in chromosome loss in nse1-103 compared to wild type cells. This was accompanied by a slight reduction in cohesion between the sister chromatids in nse1-103,suggesting a plausible mechanism for the chromosome destabilization observed in the mutant.
Since Nse1 forms part of a trimeric sub-complex with Nse3 and Nse4 in the Smc5/6 complex, we performed a yeast two hybrid assay to test the interaction of nse1-103 with Nse3 or Nse4, and found a defect in interaction of nse1-103 with Nse3 and Nse4. In addition, a defect in association of nse1-103 with Smc5 or Smc6 could be observed by performing co-immunoprecipitation from yeast cell lysates, suggesting that the integrity of the RING-domain is critical for the interaction of Nse1 with other subunits of the Smc5/6 complex. However, there was no defect in the interaction between Nse3 and Smc5 in nse1-103, indicating that the interaction of these components within the complex isindependent of Nse1.
We also identified a novel sequence motif near the RING domain of Nse1, deletion of which leads to an increased sensitivity towards genotoxic stressors and higher temperature. Biochemical characterization of this mutant also suggests a defect ininteraction with Nse3 or Nse4, and also with Smc5. The nse1 mutants also showed defects in post translational modification of Smc5 and other proteins.
Since the Smc5/6 complex also has a SUMO E3 ligase, Mms21/Nse2, we also investigated genetic interactions between the RING domain mutant,nse1-103 and the SUMO ligase RING domain defective mutant,mms21∆sl, and found an exacerbation of the drug sensitive phenotypes in thense1-103 mms21∆sl double mutant relative to either of the single mutants nse1-103 or mms21∆sl, indicating that the two proteins contribute independently to the function of Smc5/6 complex in resisting genotoxic stress.
In conclusion, the present study emphasizes the role of the RING domain of budding yeast Nse1 in resisting genotoxic stress and maintaining chromosome stability and reveals that the integrity of the RING-domain is critical for interactions of Nse1 with Nse3 and other Smc5/6 complex components. In addition, we report identification of another novel sequence motif in Nse1 that is also crucial for its interaction with other subunits of the Smc5/6 complex and for maintenance of post-translational modifications of some cellular proteins.
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Costa, Vanessa Miranda da Costa. "Desempenho e reabilitação de pontes rodoviárias : aplicação a casos de estudo." Master's thesis, 2009. http://hdl.handle.net/1822/10531.
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Dissertação de mestrado em Engenharia Civil (área de especialização em Projecto de Estruturas e Geotecnia)O progresso tem permitido o desenvolvimento das redes rodoviárias de todo o mundo e consequentemente isso reflecte-se num aumento da construção de Obras de Arte. O ritmo crescente de pontes, aliado ao controlo dos custos e prazos para a sua realização, faz com que se descuidem muitas vezes os aspectos relativos à qualidade e durabilidade das estruturas. Muitas destas pontes têm mais de 30 anos, tendo sofrido ao longo do tempo diversos mecanismos de deterioração, evidenciando as mais variadas anomalias. Para aferir as suas actuais condições segurança estrutural é necessário recorrer a metodologias de avaliação do seu desempenho, incluindo a realização de inspecções regulares. A realização de inspecções, permite avaliar a natureza e extensão das patologias, de forma a serem implementadas acções de manutenção, conservação ou reabilitação e reforço, dependendo do estado em que se encontra a estrutura. Estas acções são imprescindíveis para se manter as Obras de Arte em condições de segurança, serviço e aparência aceitável durante a sua vida útil. Neste contexto, pretende-se com esta dissertação abordar as estratégias de inspecção e de detecção de anomalias, conservação, protecção, reparação e reabilitação de Obras de Arte. É também objectivo do presente trabalho descrever os danos mais frequentes nas pontes rodoviárias e a sua correlação com factores como a idade, tipologia, material, localização, etc. Serão igualmente apresentadas soluções e técnicas de reabilitação de obras de arte em alvenaria de pedra e em betão armado, com referência a alguns casos práticos.
The progress has allowed the development of road networks around the world and consequently this is reflected in an increase in the rate of construction of bridges. The increasing demand for new bridges, combined with their strict cost control and tight deadlines, sometimes leads to negligence with respect to quality control and the long term durability of structures. Many of our current bridges have now been standing more than 30 years, and over the time have been subject to several forms of deterioration, showing many kinds of damages and much weathering. In order to assess their structural safe conditions it is necessary to make use of structural methodologies to evaluate their performance by conducting regular inspections. Periodic inspections permit a correct evaluation of the nature and the extent of the anomalies, in order to implement maintenance or rehabilitation and strengthening works, depending on the real state of the structure. These actions are essential to maintain the safety of the bridges, as well as an acceptable of service and acceptable appearance during their lifetime. The intention of this thesis is to describe suitable strategies for the inspections and detection of defects, as well as the conservation, protection, repair and rehabilitation of bridges. It is also the purpose of this work to describe the most common damages in road bridges and any correlation that exists with the age, type, materials used, location, etc.. Further, bridge rehabilitation and repair techniques of stone masonry and reinforced concrete will also be discussed, with reference to some to real-world cases.