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1
Minozzo, Fabio. "Force development during and after muscle length changes." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119614.
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Muscles are the motors of human movement. The most commonly accepted theory of muscle contraction, the "crossbridge theory", was postulated by A.F Huxley in 1957, and since then it has been widely accepted to model and explain how a muscle contracts. However, some phenomena are still not fully understood in the framework of the crossbridge theory, including the effects of muscle stretching and shortening on force production. More specifically, there is still controversy in the literature about the mechanisms responsible for the increase in force observed during and after stretch, and the decrease in force observed during and after shortening. The goal of the studies presented in this thesis was to investigate the mechanisms responsible for changes in force during and after length changes to test the following hypotheses: (i) force development during stretch is caused by crossbridges in a pre-powerstroke state, (ii) force development during shortening is affected by biasing crossbridges into pre-powerstroke, (iii) force enhancement after stretch is due to an increase in the number of attached crossbridges, (iv) force enhancement after stretch is caused by half-sarcomere non-uniformities, (v) force enhancement after stretch is caused by stiffening of non-contractile proteins induced by Ca2+, and (vi) force depression after shortening is caused by a decrease in the number of attached crossbridges. In order to achieve this goal, we developed four studies. First we investigated the mechanisms of force development (i) during stretch, and (ii) during shortening separately. We then investigated the link between the changes in force during length changes with the changes observed after length changes (iii). These three studies were performed with skinned muscle fibres from the rabbit psoas muscle. Finally, we investigated in details a potential mechanism for the residual force enhancement observed after stretch using a new preparation that we developed in our laboratory – isolated half-sarcomeres (iv). Our results suggest that (i) the force increase during stretch is largely caused by crossbridges in a pre-powerstroke state, (ii) the force decrease during shortening is related to the engagement of pre-powerstrokes only at the initial, rapid phase of force change, (iii) force enhancement after stretch is caused by an increase in the number of crossbridges attached to actin, half-sarcomere non-uniformities, and titin stiffening upon Ca2+ activation, and (iv) force depression after shortening is caused by myosin crossbridge deactivation.Les muscles sont les moteurs du mouvement humain. La théorie la plus communément reconnue de la contraction musculaire, "théorie des pontages croisés", mis en avant par AF Huxley en 1957, est depuis largement utilisée comme model d'explication afin de démontrer comment un muscle se contracte. Toutefois, certains phénomènes ne sont pas encore entièrement compris dans la structure de cette théorie, notamment les effets d'étirement et de raccourcissement du muscle sur la production de la force. D'ailleurs, il existe toujours une controverse dans la littérature sur les mécanismes responsables de l'augmentation de la force observée pendant et après l'étirement, et la diminution de la force observée pendant et après le raccourcissement. L'objectif des travaux présentés dans cette thèse est d'étudier les mécanismes responsables des changements au niveau de la force pendant et après une modification de la longueur du muscle afin de tester les hypothèses suivantes: (i) le développement de la force au cours de l'étirement est causé par les pontages croisés en pré-course de puissance, (ii) le développement de la force au cours du raccourcissement est affecté par la polarisation des pontages croisés en pré-course de puissance, (iii) l'augmentation de la force après étirement est due à une augmentation du nombre de pontages croisés attachés, (iv) l'augmentation de la force après étirement est causée par les non-uniformités du demi-sarcomère, (v) l'augmentation de la force après étirement est causée par le raidissement des protéines non contractiles induites par le Ca2+, et (vi) la diminution de la force après raccourcissement est provoquée par une diminution du nombre de pontages croisés attachés. Dans le but d'atteindre cet objectif, nous avons élaboré quatre études. D'abord, nous avons étudié séparément les mécanismes de développement de la force (i) au cours de l'étirement, et (ii) au cours du raccourcissement. Ensuite, nous avons étudié le lien entre les changements de la force observés pendant et après une modification de la longueur du muscle. (iii). Ces trois études ont été réalisées à l'aide de fibres musculaires provenant du psoas du lapin. Enfin, nous avons étudié en détail un mécanisme potentiel pour l'augmentation de la force résiduelle observée après étirement en utilisant une nouvelle préparation développée en laboratoire - demi-sarcomères isolés (iv). Nos résultats nous amènent à penser que (i) l'augmentation de la force durant l'étirement est en grande partie causée par les pontages croisés dans un état de pré-course de puissance, (ii) la diminution de la force au cours du raccourcissement du muscle est lié à l'engagement de la pré-course de puissance, seulement au moment de la phase initiale rapide du changement de la force, (iii) l'augmentation de la force après étirement est provoquée par une augmentation du nombre de ponts fixés à l'actine, des non-uniformités du demi-sarcomère et du durcissement de la titine sur l'activation du Ca2+, et (iv) la diminution de force après raccourcissement est causée par la désactivation du pontage croisé de myosine.
2
Trent, Justin David. "Transfer Length, Development Length, Flexural Strength, and Prestress Loss Evaluation in Pretensioned Self-Consolidating Concrete Members." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33161.
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The first objective of this thesis was to determine the effect of using self-consolidating concrete versus normal concrete on transfer and development lengths, and flexural strengths of prestressed members. Three small rectangular members were made, two cast with SCC mixes and one cast with a conventional mix, to determine the transfer length of each mix. Transfer lengths of both ends of each member were determined by measuring the concrete surface strains. The change in the transfer length was monitored by determining the transfer length of each member at prestress release, 7 days after release, and 28 days after release. All concrete mixes had lower than code determined transfer lengths at prestress release. Each concrete mix showed between a 12 to 56 percent increase in transfer length after 28 days. One SCC mix exceeded the ACI code stipulated 50 strand diameters 7 days after prestress transfer. The other SCC mix was consistently below the transfer length of the conventional concrete.
Separate development length members were cast in a stay-in-place steel form used for creating structural double tees. Each development length member was a stub tee. Iterative load testing was performed to determine the development length of each SCC and conventional mix. Development lengths for both SCC mixes were approximately 20 percent shorter than ACI and AASHTO code predictions. A development length for the conventional concrete was not determined due to non-repeating test data. The flexural strength of each member was determined during load testing. All concrete mixes achieved higher than the ACI predicted strengths.
The second objective of this thesis was to experimentally measure prestress losses and compare these experimental values to theoretical models. Crack initiation and crack reopening tests were performed to experimentally determine the prestress losses in each member. Three theoretical models were evaluated, the sixth edition PCI Design Handbook suggested model, a 1975 PCI Committee on Prestress Losses model, and the AASHTO LRFD prestress loss model. The crack initiation experimental values tended to be between 10 and 15 percent lower than theoretical models. In general, the crack reopening prediction of the effective prestress had a good correlation with theoretical models. This suggests crack reopening tests can be used as predictors of effective prestress, and as such, predictors of prestress losses in future experimental research. Additionally, the concrete type was shown to affect the prestress losses determined in the development length members. The SCC members tended to have higher effective prestress forces than the conventional concrete members, and thus had less prestress losses due to creep and shrinkage than the conventional concrete members.
Master of Science
3
Sharma, Sanjib. "Uniform Flow Development Length in a Rough Laboratory Flume." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1620.
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Test sections in laboratory studies should be fully developed and uniform if they are to be generalized. The objective of this study is to develop a model for predicting the uniform flow development length (Lunif) in a rough laboratory flume as a function of hydraulic parameters and bed particle roughness height (ks). Using an ADV time-averaged point velocity was measured in developing and fully developed turbulent subcritical rough open-channel flows. A series of laboratory tests were carried out in a 6.1-m-long and 0.46-m-wide rectangular channel. Tests were conducted with fine gravel (d50 = 5.8 mm, ks = 3.1d90 = 0.026 m), medium gravel (d50 = 14 mm, ks = 0.068 m), and with fine /medium gravel (d50 = 11 mm, ks = 0.04 m). For each test, longitudinal point velocity measurements were made along the center of the channel at five elevations, and at thirteen longitudinal stations. The study concluded that for flow to be uniform, the flow depth and mean cross-sectional velocity must be constant. In addition, root mean square of the fluctuating component of the velocity, RMS(u'), which is the measure of the turbulence intensity, should be uniform in order for a flow to consider uniform. Thus, RMS(u') is one of the indicative measures for determining the location where the developing flow is fully developed and uniform. The results showed that increasing the bed roughness height decreases the uniform flow development length. Using the dimensional and statistical analyses Lunif was estimated as a linear function of Reynold's particle number and Froude number.
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Hodges, Hunter Thomas. "Top Strand Effect and Evaluation of Effective Prestress in Prestressed Concrete Beams." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/36300.
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The first objective of this thesis was to assess the effect of casting orientation on bond strength in pretensioned prestressed concrete members. The "top strand effect" was evaluated through transfer and development length tests of prestressed concrete beams. Eight beams were cast with normal orientation, while four beams were cast with inverted orientation so that a significant depth of fresh concrete was placed below prestressing strands. Discrete transfer lengths were determined at the ends of each beam by measuring concrete surface strains. Inverted casting orientation caused an average 70 percent increase in transfer length. Some transfer lengths in beams with inverted casting orientation exceed current ACI and AASHTO code provisions. All measured transfer lengths were less than 90 strand diameters (45 in. for 0.5 in. diameter strands). Ranges of development length were determined through iterative load testing. The top strand effect on development length was more qualitative than quantitative. Ranges of development length in normal beams were conservatively less than code provisions. Ranges of development length in beams with inverted casting orientation were much closer to and sometimes exceeded code provisions. It is recommended that ACI and AASHTO code provisions for the development length of prestressing strand be modified to include the same magnification factors that are specified for the development length of deformed bars with twelve or more inches of fresh concrete placed below.
The second objective of this thesis was to compare experimentally measured prestress losses to theoretical calculations. Theoretical prestress losses were calculated according to PCI and AASHTO Refined methods. These methods produced similar results. Prestress losses were experimentally measured by vibrating wire gages and flexural load testing. Vibrating wire gages were used to monitor internal concrete strains. Two methods were used to reduce vibrating wire gage data: an upper/lower bound method and a basic method. The upper/lower bound method produced distorted data that was unreasonable in some cases. The basic method was more reasonable, but resulted in some prestress loss measurements that were greater than theoretical predictions. Flexural load testing was used to back calculate prestress losses from crack initiation and crack reopening loads. Prestress losses measured by crack initiation loads were generally greater than theoretical values. Losses measured by crack reopening loads were distorted. The distortion was attributed to difficulty in isolation of the correct crack reopening load. Large measurements of prestress losses by the basic vibrating wire gage and crack initiation methods suggested that losses occurred between the time when concrete was poured and prestress transfer occurred. Such losses are not accounted for in current code provisions. More research is recommended to determine the magnitude of these additional losses and their effect on design.
Master of Science
5
Nassar, Adil J. "Investigation of Transfer Length, Development Length, Flexural Strength and Prestress Loss Trend in Fully Bonded High Strength Lightweight Prestressed Girders." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32941.
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Encouraged by the performance of high performance normal weight composite girders, Virginia Department of Transportation has sought to exploit the use of high strength lightweight composite concrete (HSLWC) girders to achieve economies brought about by the reduction of dead loads in bridges. Transfer Length measurements conducted on two AASHTO Type IV HSLWC prestressed girders, resulted in an average transfer length of 17 inches, well below the AASHTO and ACI guidance.
Two girders composed of HSLWC AASHTO Type II girders and a 48" x 8" normal weight 4000-psi concrete deck were produced. The HSLWC Type II girders were cast of concretes with a compressive strength of 6380 psi and unit weight of 114 pcf. Full scale testing of the girders was conducted to evaluate development length and flexural strength in HSLWC composite girders. Embedment lengths of five, six and eight feet were evaluated. Tests indicated a development length of about 72 inches, marginally below the ACI and AASHTO stipulation. Four of eight strands in the girders showed general bond failure nevertheless, the tested girders exceeded their theoretical flexural capacity by 24 to 30 percent.
A third composite girder was cast of a high strength normal weight concrete (HSNWC) Type II girder, and topped with a 48" x 8" normal weight 4000-psi concrete deck. This girder was intended as a control specimen to contrast its test results with the HSLWC composite girders. The targeted compressive strength of both the HSLWC and HSNWC AASHTO beams was 8000 psi. The compressive strength of the HSNWC mixture, however, was about 8990 psi compared to 6380 psi for the HSLWC mixture.
Prestress losses in HSLWC AASHTO Type IV girders monitored over a nine-month period were found to be less than those calculated using the ACI and PCI models. Furthermore, the ACI model indicated that the effective prestressess retained in the HSLWC girders in 30 year's time are greater than 50% of the specified tensile strength of the strands.Master of Science
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Betts, Dean Harvey. "Analysis of telomerase activity and telomere length during early bovine development." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61967.pdf.
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Agde, Tjernlund Jessica. "Length-scale effects in yielding and damage development in polymer materials." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-485.
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Cheng, Yuqing. "A Mathematical Model to Predict Fracture Complexity Development and Fracture Length." Thesis, University of Louisiana at Lafayette, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10246182.
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Hydraulic fracturing is a commonly used practice in stimulation treatment, especially in low-permeability formation. The fracture complexity usually took place in relation to the interaction between fractures and natural rock fabrics. Despite many studies regarding the production simulation, diagnostic methods, and mathematical models about fracture complexity, research about the local complexity development is still needed for optimized stimulation design. Aiming to predict the local complexity development and stimulation performance, a hierarchy model is designed to make the problem more tractable, and a corresponding mathematical model is developed for numerical simulation. A case study is provided, and the comparison with the result of micro-seismic mapping indicates much discrepancy between field data and simulated result. Considering the many limitations of the model, the discrepancy is tolerable and acceptable. According to the sensitivity analysis, a high injection rate could serve to increase fracture complexity while reducing the maximum length of fractures. The sensitivity analyses regarding bottom-hole net pressure show a weak relationship between the fracture complexity and the bottom-hole net pressure, but a high injection pressure or low in-situ stress can serve to enhance the stimulation performance by increasing the maximum length of fractures. Sensitivity analyses for fluid properties indicate that using the high-viscosity fracturing fluid can add to the local complexity of fractures and reduce the maximum length of fractures, while fluid density has little to do with the fracture complexity and stimulation performance. The parametric study regarding rock surface energy indicates little effect of surface energy of different shale rocks on changing the local fracture complexity and stimulation performance.
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Dubey, Prachi. "Development of cardiac patches using medium chain length polyhydroxyalkanoates for cardiac tissue engineering." Thesis, University of Westminster, 2017. https://westminsterresearch.westminster.ac.uk/item/q32v3/development-of-cardiac-patches-using-medium-chain-length-polyhydroxyalkanoates-for-cardiac-tissue-engineering.
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Medium chain length-PHAs (MCL-PHAs) have properties that make them exceptional for applications in cardiac tissue engineering. Cardiovascular diseases (CVD) are a major cause of death worldwide. Cardiac patches aim to facilitate the normal functioning of the heart muscle by providing repair and support to the infarcted tissue post myocardial infarction. In this project, two MCL-PHAs, poly(3-hydroxyoctanoate) (P(3HO) homopolymer and poly(3-hydroxynonanoate-co-3-hydroxyheptanoate) P(3HN-co-3HHP) were produced from Pseudomonas mendocina CH50 using sodium octanoate and sodium nonanoate respectively as the carbon source and the growth profiles were monitored for 48 h. The polymers were characterised to confirm the chemical structure of the polymers. Different types of scaffolds were fabricated like plain films, random fibres and aligned fibres, using different ratios of P(3HO) and P(3HN-co-3HHP) which were 100:0 (P(3HO)), 20:80 (P(3HO):P(3HN-co-3HHP), 50:50 (P(3HO):P(3HN-co-3HHP), 80:20 (P(3HO):P(3HN-co-3HHP) and 0:100 P(3HN-co-3HHP). The mechanical and thermal properties of the films were analysed along with the wettability of all the scaffolds. In vitro cytocompatibility studies were also conducted on all the different scaffolds (films, random and aligned fibres) by growing human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) on them. The cells were found to be viable and healthy with comparable beating rates and calcium transients to that measured on gelatin which was used as the positive control. The cell alignment quantification on the aligned fibres indicated around 50% of the cells were aligned in one direction. Porous 5 wt% 2D scaffolds and porous 20 wt% 3D structure were fabricated using P(3HO) and different concentrations of the porogen, sucrose and NaCl respectively, to obtain pores in the size range of 250-300 μm which exhibited decreased hydrophobicity compared to the neat scaffolds. In vitro cell culture with C2C12 exhibited higher cell proliferation rate on the porous P(3HO) structures as compared to the neat P(3HO) film. The P(3HO) and PANI (polyaniline) blend scaffolds were fabricated to introduce electrical conductivity and they were analysed for their material characteristics. The effect of the addition of PANI on cardiomyocyte proliferation was studied using neonatal ventricular rat myocardial cells (NVRM). A one step method involving the use of poly(ethylene oxide-stat-propylene oxide) with isocyanate end groups (NCO-sP(EO-stat-PO) was used for the incorporation of RGD, YIGSR peptides and the vascular endothelial growth factor (VEGF) on the surface of P(3HO)/P(3HN-co-3HHP) (80:20) electrospun fibres and enhanced cell viability was studied using NVRMs.
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Burnford, Nicholas. "Development of Drape Simulation Software and the Optimisation of Variable-Length Textiles." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19867.
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The group of manufacturing methods known as Liquid Composite Moulding (LCM) is becoming the industry standard for Polymer Matrix Composite (PMC) production. These processes are versatile and cost-effective, but they are extremely dependant on the availability of textile preforms offering good quality and consistency. Good quality preforms are realised through well-controlled fibre volume fractions, fibre orientations and thicknesses as well as the absence of defects such as out-of-plane deformations and inter-fibre gaps. Preform quality is largely determined by the draping operation, which may be modeled to better inform the design of PMC components. A draping simulation software was developed in this thesis, which can simulate the draping of textiles onto model surfaces using the kinematic draping algorithm. In addition, the thesis presents a novel textile architecture where yarn spacing lengths in a textile may vary across the textile. These variable-length textiles can be custom-tailored for specific PMC applications, offering advantages over conventional constant-length textiles such as a larger surface area covered by a single piece of textile, lower values of in-plane shear, and controlled fibre orientations. The variable-length textiles can be optimised manually or using algorithms based on Monte Carlo methods which are implemented in the software. The draping simulation software was validated by comparing laboratory trials with drape simulations, and results obtained using generic demonstrators and an industrial component; several optimisation results are presented, demonstrating the advantages associated with variable-length textiles over conventional, constant-length textiles.
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Dill, Jason Cameron. "Development length of 06-inch diameter prestressing strand in high-performance concrete." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21435.
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Shekar, Sangeetha. "Development of a neural networks model to predict the diauxic lag length." [Gainesville, Fla.] : University of Florida, 2001. http://purl.fcla.edu/fcla/etd/UFE0000351.
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Thesis (M.S.)--University of Florida, 2001.Title from title page of source document. Document formatted into pages; contains viii, 118 p.; also contains graphics. Includes vita. Includes bibliographical references.
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Forster, Richard John. "Development and applications of single frequency erbium doped fibre lasers." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248516.
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Olney, Cynthia Ann. "Development of recall from short-term and long-term memory: Effects of list length, word length, taxonomic relatedness, acoustic similarity, and modality." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185567.
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An emerging theory of short-term memory, called fuzzy trace theory (FTT), postulates a link between memory and reasoning ability that might explain the relationship of performances on memory span tasks to other measures of intelligence. Two key assumptions regarding the encoding and retrieval of information in short-term memory (STM) are central to FTT. First, stored memory traces are assumed to vary along a continuum of verbatim detail to gist. Second, retrieval from STM is assumed to vary along a continuum of simple to reconstructive readout. The three experiments reported in this dissertation were designed to examine these two assumptions regarding encoding and retrieval by examining subjects' performances on memory span tasks. Memory span was the measure of choice for this series of experiments because span tasks have long been considered a pure measures of memory. Recall of items (item memory) and ordering of items for serial recall (order memory) were factored and treated as independent memory processes. The findings in the three experiments indicated that item memory relied more on simple readout of verbatim detail, while order memory relied on reconstruction from gist. More development was observed for order memory, indicating that age changes in memory span performance may be caused by development of gist extraction and reconstructive processes. It was suggested that children's ability to order items is the component of serial recall that explains the link between memory span performance and other measures of intelligence.
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Bowdey, Thomas S. "Lap Splice Development Length of Rebar in Stabilized Hollow Interlocking Compressed Earth Blocks." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1720.
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This thesis investigates the tensile performance of unconfined lap splices in specimens constructed from interlocking compressed earth block (ICEB) units. All lap splice specimens were constructed from hollow ICEB half units with one side grouting channel. ICEB units used in this research were exclusively produced from the Soeng Thai Model BP6 block press. The BP6 block press is currently manufactured in Thailand under the guidance and direction of the Center of Vocational Building Technologies (CVBT). All ICEB units and grout constructed for this research were created from mix proportions of soil, sand, cement, and water. Rebar bar sizes were restricted to M10 (#3) and M13 (#4) for all lap splice specimens due to the limited area of the hollow 2-inch diameter rebar cavity of the ICEB unit. The limited size and strength of the ICEB units also made the use of larger bar diameters impractical. Three ICEB unit types of varying strengths (3.78 MPa, 7.81 MPa, and 11.38 MPa) and three grout types of varying strengths (1.35 MPa, 7.47 MPa, and 15.50 MPa) were developed and used to construct all specimens. The measured ICEB lap splice specimen strengths were compared against the predicted strength calculated from the Masonry Standards Joint Committee (MSJC). Findings suggested that the MSJC design equation did not adequately predict the lap splice strength of specimens, particularly for specimens constructed from weaker materials. The measured ICEB lap splice results were used to create a new ICEB lap splice design equation. This paper also investigates the compressive performance of fully grouted ICEB prisms constructed from the range of ICEB unit and grout strengths stated above. Findings suggested that the compressive strength of fully grouted ICEB prisms were exclusively controlled by the compressive strength of the ICEB units used to construct the prism. The strength of the grout had no discernable effect on the strength of the fully grouted prism. A design equation was proposed to calculate prism strengths based on measured strength results of ICEB units.
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Larson, Kyle Hatch. "Evaluating the time-dependent deformations and bond characteristics of a self-consolidating concrete mix and the implication for pretensioned[sic] bridge applications." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/219.
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El, Zghayar Elie. "TRANSFER AND DEVELOPMENT LENGTH OF STRANDS IN POST-TENSIONED MEMBERS AFTER ANCHOR HEAD FAILURE." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3919.
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Post-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at the pier anchor location. Anchorage failure caused all PT force to transfer to the steel duct located within the pier segment that in turn slipped and caused the tendon to go completely slack. After the application of PT force, the anchorage assembly and steel pipes that house the tendon are filled with grout. These short grouted regions could, in the event of anchorage failure, provide a secondary anchorage mechanism preventing the scenario mentioned above from occurring. This paper presents the results of a full-scale experimental investigation on anchorage tendon pull-out and a finite element model to support the experimental results and interpretation. The study focuses on the length required to develop the in-service PT force within the pier segment grouted steel tube assembly. Seven, twelve, and nineteen 0.6Â diameter strand tendons with various development lengths were considered. Recommendations for pier section pipe detailing and design will be discussed.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering MS
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Brandani, Federico. "Development and Application of the Zero Length Column (ZLC) Technique for Measuring Adsorption Equilibria." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/BrandaniF2002.pdf.
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Barnes, Robert Wesley. "Development length of 0.6-inch prestressing strand in standard I-shaped pretensioned concrete beams /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Sapkota, Deependra. "TRIPPING OF THE BOUNDARY LAYER DEVELOPMENT LENGTH OVER ROUGH AND FULLY TURBULENT SUBCRITICAL FLUME." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1801.
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The distance required for flow entering a laboratory channel to become fully-developed and uniform can be substantial. Given the need to establish fully-developed uniform flow, if the length of a laboratory channel is not substantial then it likely that the flume cannot be used to conduct open-channel flow research. In laboratory studies where the channel bed is hydraulically rough, the noted problem can be lessened by minimizing the length over which the flow becomes fully-developed and uniform (Lunif). For this study it is hypothesized that if bed material with a roughness height (ks, ∆) is placed at the channel entrance and ks, ∆ is greater has the roughness height of bed material placed throughout the channel (ks, bed) then Lunif can be reduced. The length over which the larger bed material is referred to as the tripping zone length (∆). A second hypothesis for this study is that if ∆ is longer, then Lunif will be shorter. The primary objective of this study is to test the above mentioned hypothesis and to develop a relationship for predicting Lunif as a function of Δ. For this study, physical tests were performed in a rectangular Plexiglas flume with a variable slope. The flume was 6.1 m long, 45.7 cm wide, and 45.7 cm deep. The channel has smooth walls and the bed was lined with gravel (median particle size, d50 = 8.5 mm or 22 mm). Similarly tripping zone was lined with gravel of larger size (median particle size, d50 = 13 mm or 58 mm).Twelve tests were conducted for the study. For each test, longitudinal point velocity measurements (u) were made along the channel center, at five elevations (z), and at twelve longitudinal stations (x). An Acoustic Doppler Velocimeter was used to measure u. Lunif was determined by considering four indications of flow uniformity. Results indicate that having a tripping zone decreases Lunif and the magnitude of the decrease in Lunif was dependent on ∆. A function is presented for predicting Lunif /H = f (Rep, Fr, and Δ/H) where Rep is the Reynold's particle number, Fr is the Froude number and H is the flow depth.
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Lee, Yongho [Verfasser]. "Development of an advanced tilt actuator for tilt-to-length coupling investigations / Yongho Lee." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://nbn-resolving.de/urn:nbn:de:101:1-2021093002165433981052.
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Nielson, Annie Ruth. "Splice Performance of #6 Reinforcing Bars in Masonry with Self-Consolidating Grout." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7765.
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Reinforced masonry grouted using self-consolidating grout (SCG) is a relatively new and economically competitive option for construction, providing advantages such as reduced construction time, decreased noise and vibration, and reliable consolidation. However, SCG has different properties than conventional grout and its performance should be verified using current governing code requirements. The purpose of this research program was to determine the development length of spliced reinforcing bars in masonry grouted with SCG.Twelve masonry panels, four courses high and two and a half blocks wide, were constructed using 8-inch concrete masonry units, each with two pairs of vertically spliced #6 reinforcing bars. Six of the panels had splice lengths that met current code provisions to verify that the code requirements are adequate for use with SCG. The remaining panels had shorter splice lengths than required to investigate the possibility of shorter splices in SCG. The ultimate bond strengths were compared to the design requirement for a splice to develop 125% of the yield strength of the rein-forcing bars.All lap splices developed the required stress, including those with shorter lengths. This indicates that the current code provisions are adequate to determine the development length of reinforcement splices in masonry grouted with SCG and reinforced with #6 bars in the specific configurations tested. According to this study, a development length reduction factor may be viable when SCG is used in masonry.
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Meyer, Karl F. "Transfer and development length of 06-inch diameter prestressing strand in high strength lightweight concrete." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/20727.
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Schmid, Bryan D. (Bryan David) 1981. "Characterization of macro-length conducting polymers and the development of a conducting polymer rotary motor." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32345.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references.
Conducting polymers are a subset of materials within the electroactive polymer class that exhibit active mechanical deformations. These deformations induce stresses and strains that allow for conducting polymers to be used as an actuator for mechanical devices. Incorporation of conducting polymer actuators into mechanical devices requires electrochemical and mechanical characterization of varying polymer sample sizes and their active properties. Of particular interest, is the characterization of macro-length polymer samples, which have yet to be investigated. An understanding of conducting polymer films and their feasibility as an actuator in a mechanical device are required for the development of a conducting polymer based rotary motor. The conducting polymer, polypyrrole, was studied for its feasibility as an actuator for control surfaces on autonomous underwater vehicles. Enhancements to the actuator's performance were addressed following the feasibility study. The development of an electrochemical dynamic mechanical analyzer provides an instrument for characterization of the polymer's properties over a variety of sample sizes and actuation conditions. Finally, the application of polypyrrole as an actuator and possible enhancements combined with the characterization of macro-length polymers provides the necessary tools to develop a rotary motor. Enhancements to polypyrrole actuators in this study account for an increase in tip force of 350% and a seven fold increase in achievable strain.
(cont.) Completion of a novel electrochemical dynamic mechanical analyzer, construction of a finite rotary motor able to subtend angular displacements, and the developed embodiment of a polymer based rotary eccentric motor are accomplished in this study.
by Bryan D. Schmid.
S.M.
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Rosen, Blair Ira. "Development and application of full-length and polymerase chain reaction-derived partial-length VP4-and VP7-specific nucleic acid probes for the differentiation of porcine rotavirus serotypes /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487842372893865.
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Cross, Benjamin Thomas. "Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26190.
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The use of high compressive strengths in prestressed bridge girders can lower costs by allowing for longer spans, increased girder spacing, and smaller cross-sections. If high strength lightweight concrete (HSLWC) is used, these advantages are further enhanced due to the corresponding reduction in self-weight. Additional benefits can then be realized in the form of more traffic lanes, increased load capacity, smaller substructures, reduced crane capacity requirements, and lower shipping costs.
Despite the possible economic savings, HSLWC has been used infrequently in prestressed bridge girder applications across the nation. While recent research has been performed to extend the applicability of current bridge design specifications to normal weight concretes with strengths as high as 18 ksi, little
has been done by comparison with regards to HSLWC. The purpose of the research in this report was to assess whether current bridge design specifications for transfer length, development length, prestress loss, camber, and flexural capacity are satisfactory for use with fully-bonded, pretensioned flexural members consisting of HSLWC and to make recommendations for improvements where necessary.
Twelve high strength pretensioned beams of variable unit weight (eight lightweight beams and
four normal weight beams) and strand size (eight beams with 0.5-in. strand and four beams with 0.6-in. strand) were cast at the Thomas M. Murray Structural Engineering Laboratory at Virginia Tech. These beams were allowed to sit for a period of several months after fabrication while measurements were taken regarding transfer length, prestress loss, and camber. After this period, the beams were load tested to collect development length data, flexural data, and further data related to prestress loss. In
addition to the laboratory cast beams, prestress loss and camber data from six full-size bridge beams (five lightweight beams and one normal weight beam) cast as part of a separate project at Virginia Tech was examined. Analysis of the results for all beams shows that with a few caveats, the current AASHTO LRFD Specifications and other design methods examined regarding the topics under consideration are satisfactory for use in the design of HSLWC pretensioned bridge girders with properties similar to those of the beams studied.Ph. D.
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Carroll, James Christopher. "Grade 300 Prestressing Strand and the Effect of Vertical Casting Position." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28806.
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The purpose of this study was to investigate the influence an increase in strand strength and the effect the as-cast vertical location had on transfer length, development length, and flexural strength and to resolve the discrepancies regarding the definition of the top-bar/strand effect. Two types of test specimens were fabricated and tested investigating each respective item. The increase in strand strength was found to influence transfer length, development length, and flexural strength, while the as-cast vertical location was only found to influence transfer length, and in turn development length. Contrary to the historical definition, the top-bar/strand effect was found to be more dependent on the amount of concrete cast above the strand than the amount below it, with transfer lengths showing a steady increase with a decrease in the amount of concrete cast above the strand. As a result of the findings of this study, a new transfer length equation was proposed and a previously proposed flexural bond length equation was recommended for use in lieu of the current code provisions. The current equations for flexural strength were found to give adequate estimates for flexural strength, although a decrease in ductility was noted.Ph. D.
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Rozler, Michael. "Development of a scanning tunneling potentiometry system for measurement of electronic transport at short length scales /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Azzam, Aussama, and Mike Richter. "Investigation of Stress Transfer Behavior in Textile Reinforced Concrete with Application to Reinforcement Overlapping and Development Lengths." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77838.
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Die kontinuumsmechanische Untersuchung der Lastübertragungsmechanismen zwischen den Rovings im textilbewehrten Feinbeton trägt wesentlich zum Gesamtverständnis des mechanischen Verhaltens des Verbundmaterials bei. Neben der Erfassung der gegenseitigen Beeinflussung sich kreuzender Rovings erfordert insbesondere die mechanische Modellierung und numerische Simulation von Bewehrungsstößen und Endverankerungen die Kenntnis dieser Übertragungsmechanismen. Die numerischen Simulationen sollen u. a. zeigen, welche Endverankerungslängen und welche Übergreifungslängen an Bewehrungsstößen erforderlich sind und wie die Querbewehrung die Rissbildung beeinflusstThis paper concerns with the investigation of stress transfer mechanisms between yarns and concrete matrix and their influence on the overall behavior of textile reinforced concrete (TRC). This investigation considers textile reinforcement splices and textile reinforcement development lengths and carried out by means of Finite-Element simulations and fracture mechanic approaches. A first modeling procedure is made towards analyzing and investigating the damage mechanisms in TRC specimen under tension loading which are mainly characterized by matrix cracking and yarn pullout. This modeling approach allows for considering the yarn crack bridging which is a main characteristic behavior of TRC. In the same manner, 3D Finite-Element models are conducted for calculating the required reinforcement development lengths and the reinforcement overlapping lengths. The conducted approach takes into account different damage mechanisms observed in the corresponding experimental investigations which are also used for calibrating the modeling procedures. Moreover, the presented approach covers a wide range of required textile reinforcement overlapping lengths and development lengths and provides the corresponding ultimate loads
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Ishijima, Ken. "Length of the Eustachian tube and its postnatal development : Computer-aided three-dimensional reconstruction and measurement study." Kyoto University, 2001. http://hdl.handle.net/2433/150190.
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要旨のタイトル「耳管の長さとその生後発達 : コンピューターによる三次元再構築による測定の研究」とありKyoto University (京都大学)
0048
新制・論文博士
博士(医学)
乙第10768号
論医博第1757号
新制||医||781(附属図書館)
UT51-2001-N240
(主査)教授 塩田 浩平, 教授 橋本 信夫, 教授 伊藤 壽一
学位規則第4条第2項該当
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Mohammadebrahim, Ghaffari Mahsa, and Ghaffari Mahsa Mohammadebrahim. "Development of Full-Length Ligand-Activated Split-Kinases and Split-Phosphatases for Interrogation of Signal Transduction Pathways." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625879.
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Reversible phosphorylation controls both temporal and spatial activity of proteins within almost all signaling cascades. The human complement of >500 protein kinases and 147 protein phosphatases regulate various cellular events from cell division to cell death. The aberrant function of these proteins is implicated in diseases such as cancer, metabolic disorder and neurodegeneration. Thus, understanding the function of a specific kinase or phosphatase, by turning them on or off, is important for understanding their biology and for designing new therapies.
Toward this goal, a few emerging methods have made significant advances towards turning-on or turning-off the activity of a specific kinase. However, current methods do not necessarily allow for orthogonal control over two or more kinases or phosphatases in living cells. The major focus of this dissertation is the development of a new method for turning-on a specific kinase or phosphatase temporally, which can be used for orthogonal control of multiple kinases or phosphatases simultaneously. We hypothesized that if we could design fragmented split-kinases that can be turned on by different ligands then two or more kinases or phosphatases could be temporally controlled. We first developed a sequence dissimilarity-based approach to identify sites in the catalytic domain of kinases tolerant to a 25-residue loop insertion. The successful loop insertion sites, guided the fragmentation of the kinases at these sites into two inactive fragments, which were subsequently attached to two proteins, FKBP and FRB that dimerize in the presence of the small molecule, rapamycin. Previously we have demonstrated that the addition of rapamycin to the designed split-kinases could selectively turn-on enzymatic activity. Moreover we demonstrated that the split-enzyme approach could be extended to protein phosphatases. In this work we have successfully tested and extended the in vitro approach and designed several new split kinases and split-phosphatases. Initial studies were performed in an in vitro setting and focused on the catalytic domain of split-kinases and split-phosphatases. Importantly, we extend our design to full-length proteins and demonstrate that full-length split-kinases and split-phosphatases can be successfully controlled by addition of a small molecule ligand, rapamycin, in live cells. Moreover, the known downstream activity of full-length rapamycin-gated split-kinases, Src and Lyn, and the split-phosphatase, HePTP, were validated within signaling pathways. Thus, this work lays the foundation for future temporal interrogation of kinases and phosphatases implicated in a range of cellular pathways.
Another section of the dissertation focuses on an interesting discovery that several of these split-kinases can be mixed and matched, where half of the new chimeric enzyme is derived from one parent kinase and the other half comes from a different parent kinase. This chimeric phenomenon has interesting implications for the evolution and design of protein kinases and the approach can potentially be used to design new chimeric-protein kinases.
In summary, this work describes the design of ligand-activated split-kinases and split-phosphatases that can be used to study phosphorylation in living cells and potentially be used to rewire biological circuitry.
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Sponchiado, Aline Romani. "Face expressions in childhood : development of a picture set and investigation of developmental markers, social demographic moderators and length of presentation effects." Pontifícia Universidade Católica do Rio Grande do Sul, 2015. http://hdl.handle.net/10923/7189.
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Previous issue date: 2015Background: Emotions are fundamental across human development. Recognizing emotional face expressions in others is a valuable strategy of non-verbal communication and is particularly relevant throughout childhood given that language skills are not yet fully developed and the first interactions with peers have just started. Despite this, few studies focus on face processing in children and most of the work uses adult face stimuli, since stimuli sets with children pictures are rare. The current dissertation aimed to fill this gap through the development of the Child Emotions Pictures Set (CEPS) and investigating developmental markers of recognition of emotional faces in children aged between six and 11 years-old and the effect of age, sex and length of presentation on it. Methods: The dissertation is composed of two studies. Study I was developed in order to have a complete database that could allow Study II. The second study reports an empirical investigation of developmental markers of recognition of emotional faces in children between six and 11 years-old and the effect of sex, age and length of presentation on it. An experiment based on CEPS was presented to 90 children divided in three age groups (6-7 years-old; 8-9 years-old; 10-11 years-old) of boys and girls. Results: The final version of CEPS consists of 225 photos of 17 children, boys and girls, aged six to 11 years-old from multiracial backgrounds posing or naturally expressing the six basic emotions – happiness, fear, disgust, surprise, sadness and anger – in three intensities – low, medium and high – and neutrality. Study II reveled that happiness had the higher means of accuracy followed in sequence by disgust, surprise, anger, fear and sadness. Development of emotional face expressions recognition denote to follow childhood chronological course, although, results demonstrate a non-existence of a female advantage length of presentation does not show significant differences. Conclusion: CEPS contributes for the scientific field by making available a child face stimuli set, which is intended to be used in further developmental studies and also enables the development of cross-cultural studies in the field. We also provide further evidence about developmental markers of emotional face expressions recognition and the chronological course that it follows through childhood showing the non-existence of a female advantage on this skill and that longer exposure to stimuli does not facilitate the recognition. This method is susceptible to replication, allowing the establishment of developmental markers of emotional face expressions recognition.
Introdução: Emoções são fundamentais em todo o desenvolvimento humano. Reconhecer expressões faciais de emoções em terceiros é uma estratégia valiosa de comunicação não-verbal e é particularmente relevante durante toda a infância, uma vez que a linguagem ainda não está plenamente desenvolvida e as primeiras interações com os pares estão começando. Apesar disso, poucos estudos focam no reconhecimento de faces em crianças e a maior parte dos trabalhos utiliza estímulos adultos, uma vez que os conjuntos de estímulos com crianças são raros. A dissertação teve como objetivo preencher esta lacuna através do desenvolvimento da Child Emotions Pictures Set (CEPS) e investigar marcadores de desenvolvimento de reconhecimento de faces emocionais em crianças com idade entre seis e 11 anos e os efeitos da idade, do sexo e do tempo de apresentação sobre ele.Método: A dissertação é composta por dois estudos. O estudo I foi desenvolvido de forma a ter uma base de dados completa que poderia permitir estudo II. O segundo estudo relata uma investigação empírica de marcadores desenvolvimentais de reconhecimento de faces emocionais em crianças entre seis e 11 anos e o efeito do sexo, da idade e do tempo de apresentação do mesmo. Um experimento com base no CEPS foi apresentado a 90 crianças divididas em três grupos etários (6-7 anos de idade; 8-9 anos de idade; 10-11 anos de idade) de meninos e meninas. Resultados: A versão final do CEPS é composta de 225 fotos de 17 crianças, meninos e meninas, com idade entre seis e 11 anos de idade, de origens multirraciais que posaram ou naturalmente expressaram as seis emoções básicas - alegria, medo, nojo, surpresa, tristeza e raiva - em três intensidades - fraca, média e forte - e neutralidade. O estudo II revelou que alegria apresenta as maiores médias de acurácia e é seguida em sequencia por: nojo, surpresa, raiva, medo e tristeza. O desenvolvimento do reconhecimento das expressões de faces emocionais denota seguir o curso cronológico da infância, contudo os resultados demonstram a inexistência de uma vantagem feminina e a duração da exposição dos estímulos não apresentam diferenças significativas. Conclusão: O CEPS contribui para o campo científico, disponibilizando estímulos infantis que se destina a ser utilizado em estudos de desenvolvimento e também permite o desenvolvimento de estudos transculturais no campo. Essa dissertação fornece também mais evidências sobre os marcadores de desenvolvimento do reconhecimento de faces emocionais e do curso cronológico que decorre ao longo da infância, além de demonstrar a não-existência de uma vantagem feminina nesta habilidade e que maior tempo de exposição a estímulos não facilita o reconhecimento. Este método é suscetível a replicação, permitindo o estabelecimento de marcadores de desenvolvimento do reconhecimento de expressões faciais de emoções.
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Perkins, Jake. "Concrete fluidity effects on bond of prestressed tendons for lightweight bridge girders." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1080.
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Loflin, Bryan. "Bond and Material Properties of Grade 270 and Grade 300 Prestressing Strands." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33838.
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The first objective of this thesis was to determine the material properties of grade 270 and grade 300 prestressing strand of various sizes. Tension tests were performed on each type of strand. The data from these tests was used to determine modulus of elasticity, yield stress, ultimate stress, and ultimate elongation for each strand. The yield stresses and ultimate stresses for many of the strands did not meet the requirements found in ASTM A416. The ultimate elongation results far exceeded the requirements and the measured elastic moduli were near the modulus recommended by AASHTO LRFD. A secondary objective from the tension tests was to evaluate a gripping method which used aluminum tubing to cushion the strands against notching. The grips performed very well. Most of the strand breaks did not occur in the grips and when a strand did break in the grips, the failure occurred after significant post-yield elongation.
The second objective was to evaluate the bond properties of grade 270 and grade 300 prestressing strands. The North American Strand Producers (NASP) Bond Test and Large Block Pullout Test (LBPT) were performed on six different strand grade and strand size combinations. Both of the tests are simple pullout tests on untensioned strand. The results for each strand type were compared to one another as well as to measured transfer and development lengths from beams using the strand from the same reel. All of the strands showed sufficient bond in the beams, but one strand type did fail both the NASP Test and the LBPT. Both pullout tests were acceptable methods to evaluate strand surface condition and the benchmarks set for 0.5 in. diameter regular strand were conservative for the strands used in this thesis. Little difference was evident in the bond performance of grade 270 and grade 300 prestressing strand.Master of Science
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Stanford, Kirk Alan. "STRENGTHENING OF STEEL STRUCTURES WITH HIGH MODULUS CARBON FIBER REINFORCED POLYMERS (CFRP) MATERIALS: BOND AND DEVELOPMENT LENGTH STUDY." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-12202008-112409/.
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Cost-effective solutions for the rehabilitation and strengthening of steel structures, such as steel bridges and steel monopole towers used for cellular phone antennas, are greatly needed by government transportation departments and industry. Rehabilitation is often required due to loss of cross-section from corrosion and/or changes of the demand or use of a structure. Current techniques for strengthening steel structures have several drawbacks including requiring heavy equipment for installation, their fatigue performance, in addition to the need for ongoing maintenance due to continued corrosion attack. The current research program proposed the use of a new high modulus carbon fiber reinforced polymer (CFRP) for strengthening of steel structures. This program includes extensive research to select the resin for wet lay-up of carbon fiber sheets and the adhesives for bonding of pre-cured laminate strips. The bond behavior of FRP materials to steel structures is quite different from that of concrete structures. Preliminary test results showed the occurrence of very high bond stresses for most strengthening applications due to the amount of strengthening required for developing the material for steel structures and bridges.
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Menzl, Ina, Lauren Lebeau, Ritu Pandey, Nadia Hassounah, Frank Li, Ray Nagle, Karen Weihs, and Kimberly McDermott. "Loss of primary cilia occurs early in breast cancer development." BioMed Central, 2014. http://hdl.handle.net/10150/610119.
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BACKGROUND:Primary cilia are microtubule-based organelles that protrude from the cell surface. Primary cilia play a critical role in development and disease through regulation of signaling pathways including the Hedgehog pathway. Recent mouse models have also linked ciliary dysfunction to cancer. However, little is known about the role of primary cilia in breast cancer development. Primary cilia expression was characterized in cancer cells as well as their surrounding stromal cells from 86 breast cancer patients by counting cilia and measuring cilia length. In addition, we examined cilia expression in normal epithelial and stromal cells from reduction mammoplasties as well as histologically normal adjacent tissue for comparison.RESULTS:We observed a statistically significant decrease in the percentage of ciliated cells on both premalignant lesions as well as in invasive cancers. This loss of cilia does not correlate with increased proliferative index (Ki67-positive cells). However, we did detect rare ciliated cancer cells present in patients with invasive breast cancer and found that these express a marker of basaloid cancers that is associated with poor prognosis (Cytokeratin 5). Interestingly, the percentage of ciliated stromal cells associated with both premalignant and invasive cancers decreased when compared to stromal cells associated with normal tissue. To understand how cilia may be lost during cancer development we analyzed the expression of genes required for ciliogenesis and/or ciliary function and compared their expression in normal versus breast cancer samples. We found that expression of ciliary genes were frequently downregulated in human breast cancers.CONCLUSIONS:These data suggest that primary cilia are lost early in breast cancer development on both the cancer cells and their surrounding stromal cells.
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Roper, Aaron Brent. "Reinforcing Bar Splice Performance in Masonry with Self-Consolidating Grout." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6756.
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The use of self-consolidating grout in reinforced masonry construction provides various advantages such as reduced labor, faster construction, decreased noise pollution and better structural response. This is a relatively new building material however, and little research on self-consolidating grout's structural properties has been conducted. The purpose of this study was to analyze the performance or bond capacity of steel reinforcing bar splices in masonry with self-consolidating grout. Twelve masonry panels approximately 40 in. wide and 32 in. tall consisting of Type S mortar and concrete masonry units grouted with self-consolidating grout and No. 5 steel reinforcing bars were constructed with splice lengths as prescribed by the current design equation and splices that were slightly shorter. Test Group 1 consisted of six reinforced masonry panels with the code required lap length while Test Groups 2 and 3 had splices two and four inches shorter, respectively. The lap-splices were tested in pure tension to determine if they would fully develop the code mandated stress of 125% of the specified yield strength of the reinforcing bars. More samples were tested with the code required development length to verify if the current provision is adequate for design and the other two groups were used to explore if the required capacity could be achieved with shorter splices. All lap-splices developed the minimum required stress, even those with splices shorter than required by the design equation. For masonry with self-consolidating grout containing No. 5 bars in the specific configurations tested, the current design equation was shown to be adequate for calculating development length. Testing indicates that a reduction in required splice length for masonry with self-consolidating grout is possible.
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Costello, Kelly. "A Theoretical and Practical Analysis of the Effect of Drilling Fluid on Rebar Bond Strength." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7489.
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Drilled shafts are large cylindrical cast-in-place concrete structural elements that can be favored due to cost-effectiveness. These elements however, require strict quality control during construction to ensure a stable excavation. Drilling fluid is often used in construction to attain this stability. Drilling fluid, or slurry, can be ground water or salt water, but is typically made from a mixture of water and mineral or polymer powder to form a viscous fluid slightly more dense than ground water. During concreting, the drilling fluid is displaced by the heavier concrete, which is tremie placed at the base of the excavation from the center of the reinforcement cage. While concrete used for drilled shafts should be highly fluid, it does not follow an ideal, uniform flow. The concrete rather builds up inside the reinforcement cage to a sufficient height before then pressing out radially into the annular cover region. This concrete flow pattern associated with drilled shafts has been shown to trap slurry around/near the steel reinforcement and affect reinforcement bond strength.
Presently there are no specifications relating to slurry effects on reinforcing bar bond strength from the American Concrete Institute (ACI) or the American Association of State and Highway Transportation Officials (AASHTO). This dissertation analyzes longitudinal reinforcing bar concrete bond strength data recorded from 268 specimens constructed with tremie-placed concreting conditions in varying drilling fluids. Reinforcement used for testing were No. 8 deformed rebar. Based on the results found from this analysis, this dissertation recommends the use of a slurry modification factor to current bond strength and development length specifications.
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Messer, Lori L. "Infant-Driven Feeding vs. Scheduled Feeding: The Effect on Hospital Length of Stay." ScholarWorks, 2016. https://scholarworks.waldenu.edu/dissertations/2094.
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Developmental delays related to feeding dysfunction in premature infants can lead to lengthy hospitalizations and increased healthcare costs initially and throughout the first year of the child's life. The purpose of this project was to use readiness-to-feed assessments to evaluate the impact of an infant-driven feeding protocol on length of stay. The project compared the length of stay of 2 groups of infants: a demand fed according to a readiness-to-feed protocol (protocol group, n = 14) and a traditionally fed according to scheduled, volume-driven feedings (traditional group, n = 15). The logic model served as the change management framework and synactive theory of infant development provided the theoretical framework. According to Als' synactive theory, a shortened hospital stay for premature infants may reduce adverse effects related to neurosensory development, delayed bonding, and a distant parenting experience. A quantitative research design was used, and data were collected through a retrospective chart review of the 2 groups. Descriptive statistics and analysis of variance were completed. The findings indicated that the length of stay in the protocol group was less than the length of stay in the traditionally fed group and that the difference was statistically significant (p = 0.03). Social change benefits related to the project include improved family bonding, improved neurosensory development of infants, and a reduction in healthcare costs as a result of a shortened length of stay. The findings of this project demonstrated that by using the readiness-to-feed protocol, neonatal intensive care nurses can decrease lengths of stay and costs of hospitalization while reducing adverse effects of traditional care on infant development and bonding.
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Freeman, Marcus. "Design, development and testing of a system to measure sarcomere length by laser diffraction in working muscle in vitro." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/MQ55674.pdf.
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Basso, Trujillo Pasquale. "Bond strength of reinforcing bars with different encasement qualities : guidelines for the development length of reinforcing bars in shotcrete." Doctoral thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/69807.
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Depuis plusieurs années, le béton projeté a été utilisé pour la stabilisation des talus et le renforcement des structures dégradées. À ce jour, il est également utilisé pour construire des éléments complets tels que des murs de refend, colonnes, coquilles minces, revêtements de tunnels et poutres. Cependant, depuis quelques années, les ingénieurs en structures ont soulevé une préoccupation particulière concernant la qualité d'enrobage des barres d'armature. En effet, des imperfections peuvent être créées spécifiquement derrière les barres d'armature si le béton n'est pas projeté correctement ce qui pourrait provoquer la rupture prématurée des éléments structuraux. Essentiellement, peu de recherche a été faite à ce sujet et les recommandations courantes reposent sur des fondements entièrement empiriques servant uniquement à évaluer la qualité de l'enrobage de barres d'armature des carottes des panneaux de caractérisation. Cette étude a pour but d'augmenter les connaissances scientifiques concernant la réduction de l'adhérence entre les barres d'armature et le béton causé par ces imperfections afin d'inclure ce phénomène dans les guides destinés à l'inspection et à la conception des structures en béton projeté. Pour contrebalancer la perte d'adhérence, le cas échéant, des facteurs de modification pour l'équation de la longueur de développement des barres d'armature en traction est proposée. À cette fin, l'étude présente une phase expérimentale, une phase de modélisation et finalement une phase analytique. La phase expérimentale inclut des éprouvettes de type « pull-out » faites en béton projeté et en béton coulé ayant des vides artificiels (pour recréer les imperfections parfois observées en béton projeté). Des éprouvettes de type « beam-end » coulées avec des vides artificiels ont également été testées. La phase de modélisation inclut seulement des éprouvettes de type « beam-end » et les principaux résultats étudiés comportent la charge maximale et le type de rupture des éprouvettes, lesquels se sont montrés influencés principalement par la longueur transversale des vides (périmètre non-adhéré) et le recouvrement du béton. Les résultats ont permis d'établir des périmètres non-adhérés limites pour lesquels une rupture par déchaussement pourrait survenir. Cependant, puisqu'une certaine perte d'adhérence a été observée même avant les limites établis, la phase analytique a permis de proposer des facteurs de modification pouvant être utilisés avec l'équation de la longueur de développement. Ainsi, des recommandations ont été développées pour permettre aux ingénieurs de prendre des décisions concernant l'intégrité des structures pendant les inspections ou d'inclure le béton projeté lors de la conception de ces structures si des vides sont relevées ou susceptibles d'être créés derrière les barres d'armature.For many years, shotcrete (sprayed concrete) has been used for slope stabilization and the reinforcement of degraded structures. Nowadays, it's also used to build full-depth structural reinforced concrete elements such as shear walls, columns, thin shells, tunnel linings and girders. However, concerns regarding the encapsulation quality of the reinforcing bars have been raised by structural engineers. Indeed, imperfections could be created specifically behind the reinforcing bars if concrete is inappropriately sprayed which could cause the premature failure of structural elements. Essentially, very little research has been completed on the subject and the current guidelines rely completely on empirical evidence which serves only to evaluate the encasement quality of reinforcing bars from cores taken from pre-construction panels. This study aims to increase the scientific understanding regarding the bond stress reduction between reinforcing bars and concrete caused by the presence of such imperfections in order to include this phenomenon in the current inspection and design guidelines for shotcrete structures. To counteract the bond stress loss, if any, modification factors to be used in conjunction with the development length equation of reinforcing bars in tension is proposed. To do so, the study includes an experimental, a modeling and lastly an analytical phase. The experimental phase includes sprayed as well as cast in-place with artificial voids (to recreate the imperfections observed when shotcrete is incorrectly applied) “pull-out” specimens. Cast in-place “beam-end” specimens with artificial voids were also studied. The modeling phase only includes “beam-end” specimens and the main studied results were the ultimate load and the mode of failure of the specimens which were found to be mainly influenced by the transversal length of the voids (or un-bonded perimeters) and the concrete cover. The results allowed to establish un-bonded perimeters limits beyond which a possible reinforcing bar pull-out failure could occur. However, since a certain bar stress loss was still observed even below the limits established, the analytical phase served to propose modification factors to be used in conjunction with the development length equation. Thus, important guidelines have been created for structural engineers allowing them make decisions regarding the integrity of shotcrete structures during the inspection phase or to take into account shotcrete during the design phase of structures if imperfections are observed or are susceptible to be created behind the reinforcing bars.
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Geranmayeh, Mehran. "Development of Adaptive Image Estimate Based on Minimum Description Length Criteria for Simultaneous Noise Reduction and Compression of Image." FIU Digital Commons, 1996. https://digitalcommons.fiu.edu/etd/3832.
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Traditional image processing approaches have separated the problem of noise reduction and data compression, in a sense that the image is processed at various stages, each proposed to address specific data redundancies. Compression techniques based on Wavelets have addressed the combination of noise reduction and compression more effectively due to the application of thresholding. With that, however, the disadvantage of manual thresholding and selection of best estimating Wavelet basis is an associated limitation. This thesis will present a development of two-dimensional Adaptive Minimum Description Length (AMDL) algorithm and further expand it to an Adaptive Image Estimate by incorporating the Mean Square Error for selection of the ‘best’ threshold in reference to the ‘best’ available Wavelet basis resulting a simultaneous noise reduction and compression of images. This approach may have applications in analyzing any noisy image such as images captured by satellites on a cloudy day, medical or industrial microscopic images containing interference, and the list goes on ....
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Momeni, Amir Farid. "Effect of concrete properties and prestressing steel indentation types on the development length and flexural capacity of pretensioned concrete members." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32682.
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Doctor of PhilosophyCivil Engineering
Robert J. Peterman
A study was conducted to determine the effect of different concrete properties and prestressing steel indentation types on development length and flexural capacity of pretensioned members. Wires and strands commonly used in the manufacturing of prestressed concrete railroad ties worldwide were selected for the study. Thirteen different 5.32-mm-diameter prestressing wire types and six different strands (four, seven-wire strands and two, three-wire strands) were used to cast prisms with a square cross section. The ratio of concrete to prestressed steel in the test prism’s cross section was representable of typical concrete railroad ties. Thus, geometrical and mechanical properties of test prisms were representative of actual ties in the railroad industry. To understand the effect of concrete-release strengths and slumps on development length, all parameters were kept constant in the prisms except concrete-release strength and slump. To manufacture prisms with different release strengths, all four wires/strands were pulled and detensioned gradually when the concrete compressive strength reached 3500 (24.13 MPa), 4500 (31.03 MPa), and 6000 (41.37 MPa) psi. To determine the effect of different slumps on development length, prisms with different slumps of 3 in. (7.6 cm), 6 in. (15.2 cm), and 9 in. (22.9 cm) were manufactured and all other parameters were kept constant in prisms. All prisms were tested in three-point bending at different spans to obtain estimations of development length based on type of reinforcement, concrete-release strength, and concrete slump. Lastly, a design equation was developed based on experimental data for prediction of development length. In the last phase of load tests, cyclic-loading tests were conducted on the prisms manufactured with wires to evaluate the bond performance of wires with different indentation types under cyclic loading. A total of 210 load tests, including 14 cyclic tests, were conducted. The monotonic-load tests revealed a large difference in the development length of pretensioned concrete members manufactured with different wire/strand types and different concrete-release strengths. Also, the cyclic-load tests revealed a significant difference in bond performance of different wire types under cyclic loading compared to monotonic loading.
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Corbett, Brandon Richard. "A Pilot Study to Determine the Performance of Tension Lap Splices in Reinforced Masonry Made with Light-Weight Grout." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5661.
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The use of light-weight building materials in modern construction has resulted in efficient designs and considerable cost savings by reducing structural weight and supporting sections. This has only been possible because of many years of research to better understand the properties of the light-weight material, and its structural behaviors. However, light-weight grout is a relatively new building material in reinforced masonry construction and little is known about its structural properties. The main objective of this study was to determine if the use of light-weight grout would impact the performance of reinforcing steel, specifically development length, in masonry construction.The research included testing masonry wallettes made with normal and light-weight grout containing No. 4 (12 mm) bars with splice lengths as prescribed by the current design equation as well as splices with a modification factor. The modification factor was based on preliminary grout testing, using the procedure given in the concrete building code. The wallettes were tested in a tension test to determine if the splices were of sufficient length to fully develop the yield stress of the reinforcement.For small bar sizes, No. 4 or smaller, it is not necessary to include a modification factor when calculating development length. The minimum length of lap of 12 in. governs when No. 4 or smaller bars are used, and provides sufficient length to fully develop the yield stress of the reinforcement both for normal and light-weight grout types.
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Zhang, Lei [Verfasser], and Wilhelm [Akademischer Betreuer] Jelkmann. "Construction of infectious full-length cDNA clones of apple viruses and plant viral vector development / Lei Zhang ; Betreuer: Wilhelm Jelkmann." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1178010139/34.
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Sharma, Umesh. "Development of sustainable microbial fermentation strategies for the production of medium-chain length polyhydroxyalkanoates (mcl-PHAs) from biodiesel derived glycerol." Not applicable, 2015. http://hdl.handle.net/1993/30658.
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Bio-plastics have emerged as a promising alternative to conventional petrochemical derived plastics particularly over the past few decades. Numerous production methods for bio-plastics have been researched; however, work remains towards developing a commercially viable and economical process. The purpose of this research was to develop a sustainable fermentation strategy for production and scale-up of medium-chain length polyhydroxyalkanoates (mcl-PHAs), or bio-plastics, using a novel strain of the gram negative bacterium Pseudomonas putida, LS46, with biodiesel derived waste glycerol (WG) as feedstock. Experiments were conducted to gain a basic understanding of the general growth patterns exhibited by LS46. Thereafter, flask-batch experiments were conducted to study effects of variation in media conditions upon cell biomass production and mcl-PHA accumulation. Subsequently, optimal medium conditions observed within flasks were scaled-up and employed in the operation of a pilot-scale fermenter to increase production capacity for mcl-PHAs. It was concluded that mcl-PHA production at commercial levels could be viable with advanced process optimization.October 2015
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Lieser, Maike Danielle [Verfasser]. "LISA optical bench development : experimental investigation of tilt-to-length coupling for a spaceborne gravitational wave detector / Maike Danielle Lieser." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1169964109/34.
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Lieser, Maike [Verfasser]. "LISA optical bench development : experimental investigation of tilt-to-length coupling for a spaceborne gravitational wave detector / Maike Danielle Lieser." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1169964109/34.
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Magnusson, Victor, Cortés Daniel Petri, and Simon Wernerhag. "Does Length Matter?: An exploratory study on the current state of producers in Short Food Supply Chains." Thesis, Internationella Handelshögskolan, Jönköping University, IHH, Företagsekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-49726.
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Background: The relevance of the food system for economic, environmental and social well-being is vital to consider. However, there is a lack of research covering issues and performance assessments of the supply chains in the food industry. Due to pressures on the natural environment and unsustainable production and distribution, Short Food Supply Chains (SFSC’s) have arisen as an alternative model to conventional supply chains. However, there is a need for more research in the field as its showing to be a growing trend in the food industry. Purpose: The purpose of this research is to study the topic of SFSC, where the focus in this paper is to explore what advantages and barriers food producers experience when operating within a SFSC. Method: This study is exploratory and follows an inductive and qualitative approach, where 6 semi-structured interviews with local food producers were used to collect data. The data was analysed and connected to previous literature using a thematic analysis. Conclusion: The findings in this research illuminates that the advantages and barriers from selling through SFSC´s depends on the circumstances of the channel and the characteristics of the producers. They experienced advantages in their organization such as a high professional satisfaction, fair compensation and autonomy. The social proximity between the actors also facilitated the management of information and allowed for supply chain flexibility. However, producers also faced barriers such as the lack of proper governance in the SFSC channels, and logistical challenges such as the uncertainty of production and the difficulty of ensuring the efficiency of transportations. The analysis of SFSC’s is still in its early stages and the necessary innovations to attain the full positive effects have yet to be implemented.
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Zhao, Weixin. "Development of a portable optical strain sensor with applications to diagnostic testing of prestressed concrete." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/19764.
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Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
B. Terry Beck
The current experimental method to determine the transfer length in prestressed concrete members consists of measuring concrete surface strains before and after de-tensioning with a mechanical strain gage. The method is prone to significant human errors and inaccuracies. In addition, since it is a time-consuming and tedious process, transfer lengths are seldom if ever measured on a production basis. A rapid, non-contact method for determining transfer lengths in prestressed concrete members has been developed. The new method utilizes laser-speckle patterns that are generated and digitally recorded at various points along the prestressed concrete member. User-friendly software incorporating robust and fast digital image processing algorithms was developed by the author to extract the surface strain information from the captured speckle patterns. Based on the laser speckle measurement technique, four (4) successively improved generations of designs have been made. A prototype was fabricated for each design either on an optical breadboard for concept validation, or in a portable self-contained unit for field testing. For each design, improvements were made based on the knowledge learned through the testing of the previous version prototype. The most recent generation prototype, incorporating a unique modular design concept and self-calibration function, has several preferable features. These include flexible adjustment of the gauge length, easy expansion to two-axis strain measurement, robustness and higher accuracy. Extensive testing has been conducted in the laboratory environment for validation of the sensor’s capability in concrete surface strain measurement. The experimental results from the laboratory testing have shown that the measurement precision of this new laser speckle strain measurement technique can easily achieve 20 microstrain. Comparison of the new sensor measurement results with those obtained using traditional strain gauges (Whittemore gauge and the electrical resistance strain gauge) showed excellent agreement. Furthermore, the laser speckle strain sensor was applied to transfer length measurement of typical prestressed concrete beams for both short term and long term monitoring. The measurement of transfer length by the sensor was unprecedented since it appears that it was the first time that laser speckle technique was applied to prestressed concrete inspection, and particularly for use in transfer length measurement. In the subsequent field application of the laser speckle strain sensor in a CXT railroad cross-tie plant, the technique reached 50 microstrain resolution, comparable to what could be obtained using mechanical gauge technology. It was also demonstrated that the technique was able to withstand extremely harsh manufacturing environments, making possible transfer length measurement on a production basis for the first time.