Academic literature on the topic 'Strain analysis technique'
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Journal articles on the topic "Strain analysis technique"
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Srinivasan, S., F. Kallel, R. Souchon, and J. Ophir. "Analysis of an Adaptive Strain Estimation Technique in Elastography." Ultrasonic Imaging 24, no. 2 (April 2002): 109–18. http://dx.doi.org/10.1177/016173460202400204.
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Elastography is based on the estimation of strain due to tissue compression or expansion. Conventional elastography involves computing strain as the gradient of the displacement (time-delay) estimates between gated pre- and postcompression signals. Uniform temporal stretching of the postcompression signals has been used to reduce the echo-signal decorrelation noise. However, a uniform stretch of the entire postcompression signal is not optimal in the presence of strain contrast in the tissue and could result in loss of contrast in the elastogram. This has prompted the use of local adaptive stretching techniques. Several adaptive strain estimation techniques using wavelets, local stretching and iterative strain estimation have been proposed. Yet, a quantitative analysis of the improvement in quality of the strain estimates over conventional strain estimation techniques has not been reported. We propose a two-stage adaptive strain estimation technique and perform a quantitative comparison with the conventional strain estimation techniques in elastography. In this technique, initial displacement and strain estimates using global stretching are computed, filtered and then used to locally shift and stretch the postcompression signal. This is followed by a correlation of the shifted and stretched postcompression signal with the precompression signal to estimate the local displacements and hence the local strains. As proof of principle, this adaptive stretching technique was tested using simulated and experimental data.
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Smith Neto, P., E. S. Palma, and V. M. Figueiredo Bicalho. "Stress Analysis in Automobile Components Using Reflexive Photoelasticity Technique." Applied Mechanics and Materials 5-6 (October 2006): 117–24. http://dx.doi.org/10.4028/www.scientific.net/amm.5-6.117.
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The main objective of this work was to introduce Reflexive Photoelasticity Technique in qualifying automotive components at Fiat Automoveis S.A in Brazil. Actual stresses were determined in a simple geometry plate and also in nodes of a body shell of a passenger vehicle by using reflexive photoelasticity methodology. Initially, tests were performed in welded steel plates submitted to traction loads. These plates were previously coated with birrefringent plastic material. External loads were applied through hydraulic MTS actuators. Stress and strain distribution in welded points neighboring areas using reflexive polariscope were quantitative determined. Simultaneously, these stress and strains acting on the welded plate were determined using strain gauges. The results from both experimental techniques (photoelasticity and strain gauges) were compared with those obtained from a numerical model using finite element method. The results were correlated and analyzed. Finally, reflexive photoelasticity technique was used to determine the stresses in nodes of a body shell of a passenger vehicle. Through this analysis it was possible to determine critical points in the structure with peak stresses.
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Bieliková, L., Z. Landa, L. S. Osborne, and V. Čurn. "Characterization and identification of entomopathogenic and mycoparasitic fungi using RAPD-PCR technique." Plant Protection Science 38, No. 1 (January 29, 2012): 1–12. http://dx.doi.org/10.17221/4813-pps.
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Entomopathogenic and mycoparasitic fungi were characterised by RAPD technique, with special attention to evaluate the genetic stability of strains that are used as active ingredients in commercial biopesticides. Strain-specific fingerprints were constructed for Paecilomyces fumosoroseus – strain PFR 97 Apopka, Gliocladium virens – strain GL 21 and Verticillium lecanii – strain MYCOTAL. Genetic stability and homogeneity was confirmed among re-isolates that were obtained from commercial batches of bio-insecticide PFR 97TM 20%WDG and bio-fungicide SoilGardTM12G that had been produced in 1995–1999. RAPD analysis indicated the genetic identity of V. lecanii strains re-isolated from the two different bio-insecticides MYCOTAL<sup>®</sup> and VERTALEC<sup>®</sup>. The usefulness of RAPD technique was demonstrated when P. fumosoroseus strain PFR 97 Apopka was reliably identified after having passed through adults of the spruce bark beetle Ips typographus, and by analysis of the relationship between fungi of the genus Gliocladium.
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Baldwin, J. D., and J. G. Thacker. "A Strain-Based Fatigue Reliability Analysis Method." Journal of Mechanical Design 117, no. 2A (June 1, 1995): 229–34. http://dx.doi.org/10.1115/1.2826127.
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A new fatigue reliability technique has been developed using a strain-based analysis. A probabilistic strain-life curve, where the variability in cycles to failure at constant strain range has been modeled with a three-parameter Weibull distribution, has been incorporated into the strain-based fatigue analysis. This formulation, which includes a notch strain analysis, rainflow cycle counting and damage accumulation according to Miner’s rule, is used to estimate fatigue life to crack initiation for notched components using smooth specimen laboratory data. Unlike other probabilistic fatigue models, the technique developed here does not include a distribution model for stress peaks such as the commonly-used stationary narrow band Gaussian random process assumption but rather uses strain histories directly. Using this model, techniques have been developed to estimate the number of cycles to failure at a specified reliability and to predict the reliability and failure rate at a specified time in the analysis.
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Gallage, Chaminda, and Chamara Jayalath. "Use of Particle Image Velocimetry (PIV) technique to measure strains in geogrids." E3S Web of Conferences 92 (2019): 12007. http://dx.doi.org/10.1051/e3sconf/20199212007.
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Geosynthetics are widely used in Geotechnical Engineering to reinforce soil/gravel in pavements, retaining wall backfills, and embankments. It is important to measure strains in geogrids in the determination of their strength parameters such as tensile strength and secant stiffness, and in evaluating their performances in geogrid-reinforced structures. Strain gauges are commonly used in measuring strains in geogrids. However, it is important to verify the strains measured by strain gauges as these strains are affected by the data logging device, gauge factors, quality of bonding between grain gauge and geogrid, and temperature. Therefore, this study was conducted to verify the performance of strain gauges attached to Geogrids and also to investigate the possibility of using PIV technique and GeoPIV-RG software to measure the local strains developed in a geogrid specimen under tensile testing in the laboratory. In the experimental program of this study, six composite geogrid specimens were tested for tensile strength (wide-width tensile tests) while measuring/calculating its tensile strain by using strain gauges attached to the specimens, Geo-PIV-RG analysis and crosshead movements of Instron apparatus. Good agreement between the strains obtained from strain gauges and geoPIV-RG analysis was observed for all the tests conducted. These results suggest that the PIV technique along with geoPIV-RG program can effectively be used to measure the local strain of geogrids in the laboratory tests. It was also able to verify that properly installed strain gauges are able to measure strain in the geogrids which are used in the field applications.
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Kriven, W. M. "Strain analysis in composite ceramics." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 494–97. http://dx.doi.org/10.1017/s0424820100144012.
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Significant progress towards a fundamental understanding of transformation toughening in composite zirconia ceramics was made possible by the application of a TEM contrast analysis technique for imaging elastic strains. Spherical zirconia particles dispersed in a large-grained alumina matrix were examined by 1 MeV HVEM to simulate bulk conditions. A thermal contraction mismatch arose on cooling from the processing temperature of 1500°C to RT. Tetragonal ZrO2 contracted amisotropically with α(ct) = 16 X 10-6/°C and α(at) = 11 X 10-6/°C and faster than Al2O3 which contracted relatively isotropically at α = 8 X 10-6/°C. A volume increase of +4.9% accompanied the transformation to monoclinic symmetry at room temperature. The elastic strain field surrounding a particle before transformation was 3-dimensionally correlated with the internal crystallographic orientation of the particle and with the strain field after transformation. The aim of this paper is to theoretically and experimentally describe this technique using the ZrO2 as an example and thereby to illustrate the experimental requirements Tor such an analysis in other systems.
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Kwon, Young W. "Failure Analysis of Composite Structures Using Multiscale Technique." Materials Science Forum 995 (June 2020): 209–13. http://dx.doi.org/10.4028/www.scientific.net/msf.995.209.
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Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.
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Elmahdy, Ahmed, and Patricia Verleysen. "Challenges related to testing of composite materials at high strain rates using the split Hopkinson bar technique." EPJ Web of Conferences 183 (2018): 02021. http://dx.doi.org/10.1051/epjconf/201818302021.
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The design of sample geometries and the measurement of small strains are considered the main challenges when testing composite materials at high strain rates using the split Hopkinson bar technique. The aim of this paper is to assess two types of tensile sample geometries, namely dog-bone and straight strip, in order to study the tensile behaviour of basalt fibre reinforced composites at high strain rates using the split Hopkinson bar technique. 2D Digital image correlation technique was used to study the distribution of the strain fields within the gauge section at quasi-static and dynamic strain rates. Results showed that for the current experiments and the proposed clamping techniques, both sample geometries fulfilled the requirements of a valid split Hopkinson test, and achieved uniform strain fields within the gauge section. However, classical Hopkinson analysis tends to overestimate the actual strains in the gauge section for both geometries. It is, therefore, important to use a local deformation measurement when using these 2 geometries with the proposed clamping technique.
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Dasgupta, A., C. Oyan, D. Barker, and M. Pecht. "Solder Creep-Fatigue Analysis by an Energy-Partitioning Approach." Journal of Electronic Packaging 114, no. 2 (June 1, 1992): 152–60. http://dx.doi.org/10.1115/1.2906412.
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This study explores the possibility of using a unified theory of creep-fatigue, similar to the Halford-Manson strain-range partitioning method, for examining the effect of cyclic temperature range on fatigue life, over a wide range of temperatures. Other investigators have attempted similar techniques before for solder fatigue analysis. The present study is different since it proposes an energy-partitioning technique rather than strain-partitioning to examine the dependence of solder fatigue behavior on temperature dependent changes in the relative amounts of plastic and creep strains. The solder microstructure also dictates creep behavior but is assumed to be a given invariant parameter in this study. In other words, this study is targeted at as-cast microstructures and does not address post-recrystallization behavior. A sample solder joint of axisymmetric configuration, commonly found in leaded through-hole mounting technology, is analyzed with the help of nonlinear finite element methods. The strain history is determined for constant-amplitude temperature cycling with linear loading and unloading, and with constant dwells at upper and lower ends of the cycle. Large-deformation continuum formulations are utilized in conjunction with a viscoplastic constitutive model for the solder creep-plasticity behavior. Relevant material properties are obtained from experimental data in the literature. The results show significant amounts of rachetting and shakedown in the solder joint. Detailed stress-strain histories are presented, illustrating the strain amplitude, mean strain and residual stresses and strains. For illustrative purposes, the hysteresis cycles are partitioned into elastic, plastic and creep components. Such partitioned histories are essential in order to implement either the Halford-Manson strain-range partitioning technique or the energy-based approach suggested here, for analyzing the creep-fatigue damage accumulation in solder material. This study also illustrates the role and utility of the finite element method in generating the detailed stress-strain histories necessary for implementing the energy partitioning approach for creep-fatigue damage evaluation. Solder life prediction is presented as a function of cyclic temperature range at a given mean temperature.
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Hu, Shoufeng, and N. J. Pagano. "On the Use of a Plane-Strain Model to Solve Generalized Plane-Strain Problems." Journal of Applied Mechanics 64, no. 1 (March 1, 1997): 236–38. http://dx.doi.org/10.1115/1.2787280.
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Many composite problems are generalized plane strain in nature. They are often solved using three-dimensional finite element analyses. We propose a technique to solve these problems with a plane-strain model, which is achieved by introducing some artificial out-of-plane thermal strains in a two-dimensional finite element analysis. These artificial thermal strains are chosen such that an identical stress field is obtained, while the actual strains and displacements can also be determined.
Dissertations / Theses on the topic "Strain analysis technique"
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Chevallier, Elise Camille. "Assessment of welding induced plastic strain using the thermoelastic stress analysis technique." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/420750/.
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The work presented in the thesis is dedicated to the development and validation of a new technique to assess plastic strain based on thermoelastic stress analysis (TSA). Welding induced plasticity (WIP) and welding residual stresses can negatively affect the structural integrity of welded structures as they can exacerbate creep and stress corrosion cracking and limit the structure’s resistance to failure. Moreover, WIP has been shown to negatively affect weld integrity, since the associated accumulation of defects (dislocations) in the material will accelerate the nucleation of macro-scale defects that lead to component failure. There has been considerable amount of work published on determining the magnitude and distribution of the residual stresses both experimentally and by using numerical techniques. WIP can be predicted using finite element analysis (FEA), however, there is currently no standardised experimental method to characterise plastic strain and hence, model predictions are not readily validated with confidence. Recently, two techniques, based on electron backscatter diffraction and indentation respectively, were developed to assess WIP. However, both techniques are destructive and would not be applicable on in-situ components. TSA is a non-contact stress analysis method which is quick to apply and fully portable. TSA is based on the measurement of a small temperature change that occurs as a result of a change in the stress. The small temperature change is measured using an infrared detector. A method for plastic strain assessment (PSA) using TSA has been proposed based on the change in the thermoelastic response due to the plastic strain a material has experienced during a process, e.g. deformation or welding. TSA has the potential to be the first nondestructive, non-contact plastic strain assessment technique, termed as TSA-PSA. The aim of the PhD is to investigate the potential of using the TSA-PSA approach for assessing WIP in austenitic (AISI 316L) and ferritic (SA508 Gr.3 Cl.1) steels. The influence of welding induced microstructural changes on the thermoelastic response is investigated to establish any changes in the thermoelastic response relating to plastic straining only. The study focuses on two typical nuclear grade steels; ferritic SA508 Gr.3 Cl.1 and austenitic stainless steel AISI 316L. The effect of plastic strain on the thermoelastic response of both steels is investigated through the design and assessment of a calibration specimen used to determine the thermoelastic constant variation with plastic strain alongside with microstructural changes. It was found that the plastic strain has a stronger influence on the thermoelastic constant in SA508 than in AISI 316L. For uniform microstructures the influence of plastic strain on the thermoelastic response can be defined and, a larger influence of plastic strain on thermoelastic response was reported for coarse grains of austenite in AISI 316L and coarse grains of ferrite in SA508. The second part of the work concerns development finite element (FE) models of weld mock-ups to demonstrate application of TSA-PSA. The modelling enabled the plastic strain experienced during welding to be predicted and adjustments made to the design prior to the mock-up manufacture. Once satisfied that the mock-ups were suitable for TSA, they were manufactured at TWI Ltd. TSA experimental work was conducted on each mock-up and the outcome was compared with the outputs from the calibrated FE models. The capability of TSA to identify plastic strain in welded components is assessed through the use of the weld mock-ups. The thesis makes a novel contribution to the development of TSA as a portable non-destructive, non-contact technique to assess WIP in components with the investigation of the influence of microstructural changes similar to that found in welds on the technique, as well as the design, manufacture and plastic strain predictions in weldments dedicated to the technique. The results indicate a stronger influence of the plastic strain on the thermoelastic constant in coarse-grained microstructure in both grades of steel.
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Kuppuswamy, Anand. "Theoretical and experimental analysis of strain concentration around a broken fiber using the macro-composite technique." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-09182008-063050/.
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Kabeer, Saqib. "Application of image analysis techniques to determine strain distribution in leather." Thesis, University of Northampton, 2006. http://nectar.northampton.ac.uk/2672/.
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The optimum cutting of various parts of a shoe, prior to shoe manufacture requires knowledge of the topographical variation of what are termed “lines of tightness”. Currently the cutting operation for shoe parts is guided by a general assumption about the pattern of the lines of tightness. There is a need to have available a system which can determine, in a non-destructive way, the lines of tightness in an indvidual piece of leather. Initially an image analysis system was developed to investigate the uni-axial deformation behaviour of leather. This technique provided more information about the stress-strain behaviour of a leather sample along the gauge length than a conventional mechanical test and it was possible to accurately measure the strain distribution along the gauge length. A system was developed which could determine the relative displacement of marked spots along the gauge length of the sample using images captured during a uni-axial, bi-axial or multi-axial tensile test. The separation of the marked spots along the direction of applied stroke allowed the determination of longitudinal strain while contraction across the width was also measured in some cases, which was useful in calculating the Poisson’s ratio of leather for which a great variation was observed between different locations (Butt, Belly, Neck etc). Various approaches were investigated to determine the lines of tightness. Firstly, the local Poisson’s ratio was observed since a higher value of this parameter was associated with these lines of tightness. Secondly, biaxial stretching of leather by a series of actuators for each axis indicated the lines of tightness along the actuator with lower strain values. Thirdly, the strain was measured when the leather was stretched along number of known axes. This latter technique appeared to be the best approach and mathematical modeling was investigated to provide further refinement. A mechatronics-based device by industrial application of the third approach was also proposed. The software was written using a graphical programming system (LabVJ EW)
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Kourmpetis, Miltiadis P. "The development of strain sensors and analysis techniques for the power industry." Thesis, King's College London (University of London), 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485422.
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Power generation companies are under a great deal of Government and other pressure to achieve and maintain their plants to a high efficiency standard with minimum release of CO2 into the atmosphere. Achieving and maintaining the required high level of operational integrity of large complex generating plants is a demanding task. One key requirement is to have data on the functional integrity of all major components of a power station plant This is to provide for removal from the plant of time expired components. This is particularly important for components that can only be replaced by shutting down the plant and having to do this very often is a problem. This dissertation relates to the life monitqfing of steam pipes and other components that are .subject to· demanding high temperatures and stresses. Life monitoring· of these components requires instrumentation that can withstand for long periods these very hostile conditions on and about the steam pipes. Creep monitoring is one key requirement and sensors need to be able to detect very small growth movements of the material and have the ability not to be affected by the hostile environment in which they are located. Ideally, for creep monitoring in steam pipe material, required is a precise point-to-point measurement in two or more directions together with strain mapping of the region in and about the point-ta-point sensors. E.ONUK is supporting this research to improve their life-monitoring systems and in so doing have regard for the trend to use even high temperature steam pipes in the next generation of power stations. To illustrate the above in this thesis, the development of a Strain Monitoring System is presented: the Auto Reference Creep Management And Control System (ARCMAC). This is a strain sensor system which is developed at Imperial College in collaboration with E.ON. UK. From design studies and operational experience of pipe degradation rates and failures, useful information is available as to parts of the pipe system that need to be monitored to obtain reliable data on the remaining life of the pipes. Also known is that a good and feasible monitoring method to reveal the onset of failure processes is the measurement of the increases in micra-strain generated in the outer skin of the pipe material. For these measurements, the ARCMAC system has been developed. The ARCMAC measurement system utilizes precision optics to capture successive images of a 'target' strain gauge and digital image processing is used to obtain estimates of creep s~in accumulated over the plant-operating period. The Digital Image Correlation (DIC) technique is also presented as an alternative measurement technique. In this technique a series of digital images of a surface is uSed under various levels of load, upon which a paint pattern has been applied. The first such pattern to be used in the UK on a power station was applied in Ratcliffe power station as part of this study. The DIC technique will be used in conjunction with ARCMAC gauges to evaluate any unusual strain distribution surrounding the gauge area in an effort to create a unified Strain Monitoring System combining both techniques. Full field case studies are examined and presented showing encouraging initial results.
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Yang, Peiyu. "Experimental Techniques and Mechanical Behavior of T800/F3900 at Various Strain Rates." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480601677646997.
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Kalpundi, Ganesh R. "Nonlinear mixed finite element analysis for contact problems by a penalty constraint technique." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06302009-040252/.
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Crammond, G. "Development of optical techniques for the experimental analysis of local stress and strain distributions in adhesively bonded composite joints." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355981/.
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This research seeks to evaluate the local stress and strain distributions formed in adhesively bonded composite joints under quasi static and high strain rate loading. A literature review of current analytical, numerical and experimental studies of adhesively bonded joints is presented and identifies the lack of knowledge in the behaviour of composite bonded joints in the through-thickness direction. Detailed analysis of the stress and strain in the joint, and their impact on the development of damage prior to and during failure have been obtained using Digital Image Correlation (DIC). An experimental methodology is established to perform DIC at the mesoscopic scale using high magnification optics, enabling accurate, high spatial resolution analysis of the strains around the geometric discontinuity between adherends. It is demonstrated that the small through-thickness strains are critical in the development of damage in the joint around the discontinuity between adherends. Errors in the DIC technique are assessed using a robust morphological methodology to evaluate the quality of different speckle patterns based upon the properties of the speckles in the pattern. The strain data is manipulated to evaluate the principal stresses in the joint, which govern failure in the brittle epoxy matrix of the composite, providing a concise evaluation of the transfer of load between the adherends and damage initiation within the joint. The DIC results and methodology are validated against independent infra-red measurements using Thermoelastic Stress Analysis (TSA). Limitations in the TSA analysis approach are identified around joint discontinuity due to the varying principal stress direction. A new TSA analysis methodology is presented to overcome this. The results of the experimental analysis are used to validate a representative 2D finite element model modelling approach for adhesively bonded joints, showing good agreement to the experimental data. Finally the full-field DIC methodology is applied to analyse the response of a single lap joint during high strain rate loading, providing unprecedented full-field measurement of the strain fields up to failure.
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Box, Matthew. "Multiple-locus variable-number tandem-repeat analysis (MLVA) for clonal characterization of methicillin resistant Staphylococcus aureus strains." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2006. https://www.mhsl.uab.edu/dt/2008r/box.pdf.
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Wang, Yi. "Damage assessment in asymmetric buildings using vibration techniques." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/120475/1/Yi_Wang_Thesis.pdf.
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This research presents a step forward in the area of structural health monitoring by developing the scientific basis for a method to detect and locate damage in asymmetric building structures accurately and efficiently. The method is based on the changes in the vibration characteristics of asymmetric buildings such as natural frequencies and associated mode shapes. The thesis first investigated the difference in vibration behavior between symmetric and asymmetric buildings and compared the capability of different damage detection methods that uses the vibration characteristics. Then a modified method (MMSE) and an improved method (MCA-DI) were proposed based on the comparative study and verified through experimental testing of a laboratory scale asymmetric setback structure model.
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Hamilton, Bryan. "DNA Analysis of Surfactant Associated Bacteria in the Sea Surface Microlayer in Application to Satellite Remote Sensing Techniques: Case Studies in the Straits of Florida and the Gulf of Mexico." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/39.
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Several genera of bacteria residing in the sea surface microlayer and in the near-surface layer of the ocean have been found to be involved in the production and decay of surfactants. Under low wind speed conditions, surfactants can suppress short gravity capillary waves at the sea surface and form natural sea slicks. These features can be observed with both airborne and satellite-based synthetic aperture radar (SAR). Using a new microlayer sampling method, a series of experiments have been conducted in the Straits of Florida and the Gulf of Mexico in 2013 to establish a connection between the presence of surfactant-associated bacteria in the upper layer of the ocean and sea slicks. In a number of cases, sampling coincided with TerraSAR-X and RADARSAT-2 satellite overpasses to obtain SAR images of each study site. Samples collected from slick and non slick conditions have been analyzed using real time PCR techniques to determine Bacillus relative abundance in each area sampled. Previous work has shown that the sea surface microlayer plays a role in air-sea gas exchange, sea surface temperature, climate-active aerosol production, biochemical cycling, as well as the dampening of ocean capillary waves. Determining the effect of surfactant-associated bacteria on the state of the sea surface may help provide a more complete global picture of biophysical processes at the air-sea interface and uptake of greenhouse gases by the ocean.
Books on the topic "Strain analysis technique"
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Techniques of tomographic isodyne stress analysis. Dprdrecht: Kluwer Academic Publishers, 2000.
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Xin-Qun, Zhu, ed. Moving loads: Dynamic analysis and identification techniques. London: CRC Press, 2011.
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Viotti, Matias R. Robust speckle metrology: Techniques for stress analysis and NDT. Bellingham, Washington USA: SPIE Press, 2014.
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Savage, Karen Teresa. A study of Plasmid DNA analysis techniques for the identification and epidemiological typing of Staph. Epidermidis strains. [s.1: The Author], 1989.
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Cameli, Matteo, Partho Sengupta, and Thor Edvardsen. Deformation echocardiography. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198726012.003.0004.
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Echocardiographic strain imaging, also known as deformation imaging, has been developed as a means to objectively quantify regional and global myocardial function. First introduced as a post-processing feature of tissue Doppler imaging velocity converted to strain and strain rate, strain imaging has more recently also been derived from speckle tracking analysis. Tissue Doppler imaging yields velocity information from which strain and strain rate are mathematically derived whereas two-dimensional speckle tracking yields strain information from which strain rate and velocity data are derived. Data obtained from these two different techniques may not be equivalent due to limitations inherent with each technique. Speckle tracking analysis can generate longitudinal, circumferential, and radial strain measurements and left ventricular twist. Although potentially useful, these measurements are also complicated and frequently displayed as difficult-to-interpret waveforms. Strain imaging is now considered a robust research tool and has great potential to play many roles in routine clinical practice. This chapter explains the fundamental concepts of deformation imaging, the technical features of strain imaging using tissue Doppler imaging and speckle tracking, and the strengths and weaknesses of these methods.
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Goadsby, John Morgan *. A comparison of multi-dimensional strain techniques for deformation analysis. 1989.
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Pindera, A. Techniques of Isodyne Stress Analysis (Solid Mechanics and Its Applications). Springer, 2001.
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C, Thompson Randolph, and Dryden Flight Research Facility, eds. Single-strain-gage force/stiffness buckling prediction techniques on a hat-stiffened panel. Edwards, Calif: NASA Ames Research Center, Dryden Flight Research Facility, 1991.
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C, Thompson Randolph, and Dryden Flight Research Facility, eds. Single-strain-gage force/stiffness buckling prediction techniques on a hat-stiffened panel. Edwards, Calif: NASA Ames Research Center, Dryden Flight Research Facility, 1991.
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Single-strain-gage force/stiffness buckling prediction techniques on a hat-stiffened panel. Edwards, Calif: NASA Ames Research Center, Dryden Flight Research Facility, 1991.
Find full textBook chapters on the topic "Strain analysis technique"
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Laermann, Karl-Hans. "Hybrid Technique to Analyze 3-D Stress - Strain States." In Applied Stress Analysis, 639–48. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0779-9_61.
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Sun, Y. F., and John H. L. Pang. "Nanoscale Deformation and Strain Analysis by AFM/DIC Technique." In Nano-Bio- Electronic, Photonic and MEMS Packaging, 695–718. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/978-1-4419-0040-1_19.
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Sun, Y. F., and John H. L. Pang. "Nanoscale Deformation and Strain Analysis by AFM–DIC Technique." In Nano-Bio- Electronic, Photonic and MEMS Packaging, 519–33. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-49991-4_23.
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Kunio, Takeshi, Yasushi Miyano, and Suguru Sugimori. "Fundamentals Of Photoviscoelastic Technique For Analysis Of Time And Temperature Dependent Stress And Strain." In Applied Stress Analysis, 588–97. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0779-9_56.
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Forquin, P., F. Gatuingt, and G. Gary. "A Testing Technique of Confined Compression for Concrete at High Rates of Strain." In Experimental Analysis of Nano and Engineering Materials and Structures, 451–52. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6239-1_224.
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Hillery, M. T., and V. J. McCabe. "A Photo-Elastic and Strain Gauge Technique of Stress Analysis in Rod-Drawing." In Proceedings of the Thirtieth International MATADOR Conference, 485–91. London: Macmillan Education UK, 1993. http://dx.doi.org/10.1007/978-1-349-13255-3_62.
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Haddadi, H., and S. Belhabib. "An Attempt to Identify Hill’s Yield Criterion Parameters Using Strain Field Measured by Dic Technique." In Experimental Analysis of Nano and Engineering Materials and Structures, 677–78. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6239-1_336.
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Mei, Liu, Sen Guo, Tiansheng Shi, Zejie Pan, Weiwen Li, and Feng Xing. "3D-DIC Technique for Strain Measurement in FRP Strip Externally Bonded to Concrete Specimens." In Advances in 3D Image and Graphics Representation, Analysis, Computing and Information Technology, 1–11. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3867-4_1.
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Shah, Haroun N., Ajit J. Shah, Omar Belgacem, Malcolm Ward, Itaru Dekio, Lyna Selami, Louise Duncan, et al. "MALDI-TOF MS and currently related proteomic technologies in reconciling bacterial systematics." In Trends in the systematics of bacteria and fungi, 93–118. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789244984.0093.
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Abstract This book chapter presents an overview and discussion of the use of MALDI-TOF MS for fungal identification. The major known limitations of the technique for fungal taxonomy, and how to overcome these, are also discussed. Moreover, this should guarantee that spectra deposited in such MALDI-TOF MS database would remain public, preferably in open free access. To avoid misidentification, these stored spectra must be curated and based on well-established standard operating procedures. The number of spectra available within species needs to be increased to accommodate the diversity and geographic differences, unique strain traits and the varied culture conditions and procedures in order to establish a single public and open access MALDITOF MS database. This could then be used with metadata analysis and artificial intelligence algorithms, to provide reliable fungal identification.
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Pamuk, Ahmet, and Korhan Adalier. "Alternative Remedial Techniques for Sheet-Piled Earth Embankments." In Soil Stress-Strain Behavior: Measurement, Modeling and Analysis, 921–30. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6146-2_70.
Full textConference papers on the topic "Strain analysis technique"
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Winther, Svein, and Gudmunn A. Slettemoen. "An ESPI Contouring Technique In Strain Analysis." In Symposium Optika '84, edited by Gabor Lupkovics and Andras Podmaniczky. SPIE, 1985. http://dx.doi.org/10.1117/12.942383.
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Dutta, Ankur. "Bridge strain data analysis using density based clustering technique." In 2015 IEEE International Conference on Research in Computational Intelligence and Communication Networks (ICRCICN). IEEE, 2015. http://dx.doi.org/10.1109/icrcicn.2015.7434227.
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Chism, Kyle B., Jack Kawell, and James P. Hubner. "Luminescent Measurement Technique for Analysis of Dynamic Pressure and Strain Fields." In AIAA Aviation 2019 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-3150.
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Okoloekwe, Chike, Muntaseer Kainat, Doug Langer, Sherif Hassanien, J. J. Roger Cheng, and Samer Adeeb. "Deformation Analysis of Dented Pipeline via Surface Interpolation." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65523.
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Advances in the interpolation techniques of discrete data points and its application to monitoring the displacement of physical infrastructure has led to improved analytical strain evaluation procedures. In order to generate a detailed mathematical model of the strain state of a dented pipeline, it is necessary to decompose the deformation data obtained from monitoring devices into the corresponding radial, longitudinal and circumferential components. In this paper, a technique for analytically evaluating the strains in dented pipelines based on the coordinates of the geometric profile of the dent is investigated and the strains predicted from the said method are benchmarked against the strains predicted from a numerical model generated using nonlinear finite element analysis (FEA) and the codified equations for evaluating strains in dented pipes. This novel technique to strain analysis is an application of the principles of shell theory to a deformed pipeline in order to evaluate the components of the displacements in the cylindrical coordinate system. The coordinates of the deformed profile are obtained from the FEA model and interpolated with B-Splines curves equipped with second order continuity. The resulting strain distribution along the thickness of the pipe wall is evaluated analytically by performing derivatives on the spline functions. The good agreement obtained in the strains predicted by our model and FEA indicates a possibility of conducting in-depth strain analysis of thin-walled structures without the need for the rigorous FEA.
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Elgaud, M. M., M. S. D. Zan, A. A. G. Abushagur, and A. Ashrif A. Bakar. "Analysis of independent strain-temperature fiber Bragg grating sensing technique using OptiSystem and OptiGrating." In 2016 IEEE 6th International Conference on Photonics (ICP). IEEE, 2016. http://dx.doi.org/10.1109/icp.2016.7510036.
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Chung, Jayhoon, Guoda Lian, and Lew Rabenberg. "Local Lattice Strain Measurement Using Geometric Phase Analysis of Dark Field Images from Scanning Transmission Electron Microscopy." In ISTFA 2011. ASM International, 2011. http://dx.doi.org/10.31399/asm.cp.istfa2011p0024.
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Abstract Since strain engineering plays a key role in semiconductor technology development, a reliable and reproducible technique to measure local strain in devices is necessary for process development and failure analysis. In this paper, geometric phase analysis of high angle annular dark field - scanning transmission electron microscope images is presented as an effective technique to measure local strains in the current node of Si based transistors.
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Artoni, Alessio, Matilde Tomasi, and Francesca Di Puccio. "Kinematic Analysis of the Lolotte Technique in Rock Climbing." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67595.
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The lolotte or drop-knee technique is a fundamental of rock climbing that particularly involves lower limbs, and especially knee joints. To the authors’ best knowledge, no biomechanical analysis of the lolotte seems to have ever been conducted, despite its widespread use. As a first contribution to this research topic, the present work deals with an athlete-specific kinematic analysis of the lolotte aimed at quantifying the hip and knee joint angle trajectories and knee ligament strains. A marker-based motion capture system was employed to track the execution of the lolotte on a purposely designed climbing structure. The marker trajectories were then used as input for a numerical simulation in the OpenSim program, where an athlete-specific musculoskeletal model was set up to perform an inverse kinematics analysis and obtain the joint angle trajectories as well as their ranges of motion. Further processing of the model allowed to estimate the strain of the knee medial collateral ligament. Such kinematic analysis revealed characteristic hip and knee joint angle patterns and highlighted a critical phase in which the knee is considerably abducted (increased valgus). As a consequence, the medial collateral ligament is remarkably recruited, thereby substantiating the claim diffused among climbers that drop-kneeing may cause ligament injury.
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Prabhakara, Viveksharma. "Strain measurement and analysis in semiconductor FinFET devices using a novel moiré quadrature demodulation technique." In European Microscopy Congress 2020. Royal Microscopical Society, 2021. http://dx.doi.org/10.22443/rms.emc2020.940.
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Morris, Randal P., Michael J. Grecula, William L. Buford, and Rita M. Patterson. "Quantification of Femoral Surface Strain After Cementless Stem Implantation by Computer Analysis of the Photoelastic Method." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0267.
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Abstract Cementless femoral stems have been associated with surface strain changes and stress shielding after total hip arthroplasty. The changes may lead to post-operative bone resorption, micromotion, microfracture or implant failure. Therefore, detailed analysis of femoral surface strain before and after implantation can be useful in determining the features of implant designs that promote strain changes. The purpose of this research is to determine to what affect different cementless stem designs have on the surface strains of the femur. This protocol will follow a technique developed in a pilot study that uses the photoelastic method to resolve the fringe patterns on the femur, commercially available computer software to image these patterns, and original software programs to analyze the surface strains and provide comparative data.
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Lyamina, Elena. "On the Prediction of the Strain Rate Intensity Factor in Metal Forming Processes." In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59186.
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The strain rate intensity factor is the coefficient of the principal singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. Such singular behaviour occurs in the case of several rigid plastic models (rigid perfectly plastic solids, the double-shearing model, the double slip and rotation model, some of viscoplastic models). Since it is only possible to introduce the strain rate intensity factor for singular velocity fields, it is obvious that standard finite element codes cannot be used to calculate it. The currently available distributions of the strain rate intensity factor have been found from closed form solutions or with the use of simple approximate solutions (for instance upper bound solutions). Closed form solutions are available for boundary value problems with simple geometry (flow through infinite rough channels, compression of infinite layers between rough plates and so on) and, therefore, are mostly of academic interest. Simple approximate solutions can predict general tendencies in the distribution of the strain rate intensity factor but cannot predict its distribution with a sufficient accuracy for industrial applications. For, the strain rate intensity factor reflects a very local effect inherent in the velocity field whereas simple approximate methods, such as the upper bound method, estimate global parameters, such as the limit load. The purpose of the present research is to propose a special numerical technique for calculating the strain rate intensity factor in the case of plane strain deformation of rigid perfectly plastic materials and to verify it by means of comparison with an analytical solution. The technique is based on the method of Riemann.
Reports on the topic "Strain analysis technique"
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Morrison, Mark, and Joshuah Miron. Molecular-Based Analysis of Cellulose Binding Proteins Involved with Adherence to Cellulose by Ruminococcus albus. United States Department of Agriculture, November 2000. http://dx.doi.org/10.32747/2000.7695844.bard.
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At the beginning of this project, it was clear that R. albus adhered tightly to cellulose and its efficient degradation of this polysaccharide was dependent on micromolar concentrations of phenylacetic acid (PAA) and phenylpropionic acid (PPA). The objectives for our research were: i) to identify how many different kinds of cellulose binding proteins are produced by Ruminococcus albus; ii) to isolate and clone the genes encoding some of these proteins from the same bacterium; iii) to determine where these various proteins were located and; iv) quantify the relative importance of these proteins in affecting the rate and extent to which the bacterium becomes attached to cellulose. BARD support has facilitated a number of breakthroughs relevant to our fundamental understanding of the adhesion process. First, R. albus possesses multiple mechanisms for adhesion to cellulose. The P.I.'s laboratory has discovered a novel cellulose-binding protein (CbpC) that belongs to the Pil-protein family, and in particular, the type 4 fimbrial proteins. We have also obtained genetic and biochemical evidence demonstrating that, in addition to CbpC-mediated adhesion, R. albus also produces a cellulosome-like complex for adhesion. These breakthroughs resulted from the isolation (in Israel and the US) of spontaneously arising mutants of R. albus strains SY3 and 8, which were completely or partially defective in adhesion to cellulose, respectively. While the SY3 mutant strain was incapable of growth with cellulose as the sole carbon source, the strain 8 mutants showed varying abilities to degrade and grow with cellulose. Biochemical and gene cloning experiments have been used in Israel and the US, respectively, to identify what are believed to be key components of a cellulosome. This combination of cellulose adhesion mechanisms has not been identified previously in any bacterium. Second, differential display, reverse transcription polymerase chain reaction (DD RT-PCR) has been developed for use with R. albus. A major limitation to cellulose research has been the intractability of cellulolytic bacteria to genetic manipulation by techniques such as transposon mutagenesis and gene displacement. The P.I.'s successfully developed DD RT- PCR, which expanded the scope of our research beyond the original objectives of the project, and a subset of the transcripts conditionally expressed in response to PAA and PPA have been identified and characterized. Third, proteins immunochemically related to the CbpC protein of R. albus 8 are present in other R. albus strains and F. intestinalis, Western immunoblots have been used to examine additional strains of R. albus, as well as other cellulolytic bacteria of ruminant origin, for production of proteins immunochemically related to the CbpC protein. The results of these experiments showed that R. albus strains SY3, 7 and B199 all possess a protein of ~25 kDa which cross-reacts with polyclonal anti-CbpC antiserum. Several strains of Butyrivibrio fibrisolvens, Ruminococcus flavefaciens strains C- 94 and FD-1, and Fibrobacter succinogenes S85 produced no proteins that cross-react with the same antiserum. Surprisingly though, F. intestinalis strain DR7 does possess a protein(s) of relatively large molecular mass (~200 kDa) that was strongly cross-reactive with the anti- CbpC antiserum. Scientifically, our studies have helped expand the scope of our fundamental understanding of adhesion mechanisms in cellulose-degrading bacteria, and validated the use of RNA-based techniques to examine physiological responses in bacteria that are nor amenable to genetic manipulations. Because efficient fiber hydrolysis by many anaerobic bacteria requires both tight adhesion to substrate and a stable cellulosome, we believe our findings are also the first step in providing the resources needed to achieve our long-term goal of increasing fiber digestibility in animals.
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Lichter, Amnon, Gopi K. Podila, and Maria R. Davis. Identification of Genetic Determinants that Facilitate Development of B. cinerea at Low Temperature and its Postharvest Pathogenicity. United States Department of Agriculture, March 2011. http://dx.doi.org/10.32747/2011.7592641.bard.
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Botrytis cinerea is the postharvest pathogen of many agricultural produce with table grapes, strawberries and tomatoes as major targets. The high efficiency with which B. cinerea causes disease on these produce during storage is attributed in part due to its exceptional ability to develop at very low temperature. Our major goal was to understand the genetic determinants which enable it to develop at low temperature. The specific research objectives were: 1. Identify expression pattern of genes in a coldenriched cDNA library. 2. Identify B. cinerea orthologs of cold-induced genes 3. Profile protein expression and secretion at low temperature on strawberry and grape supplemented media. 4. Test novel methods for the functional analysis of coldresponsive genes. Objective 1 was modified during the research because a microarray platform became available and it allowed us to probe the whole set of candidate genes according to the sequence of 2 strains of the fungus, BO5.10 and T4. The results of this experiment allowed us to validate some of our earlier observations which referred to genes which were the product of a SSH suppression-subtraction library. Before the microarray became available during 2008 we also analyzed the expression of 15 orthologs of cold-induced genes and some of these results were also validated by the microarray experiment. One of our goals was also to perform functional analysis of cold-induced genes. This goal was hampered for 3 years because current methodology for transformation with ‘protoplasts’ failed to deliver knockouts of bacteriordopsin-like (bR) gene which was our primary target for functional analysis. Consequently, we developed 2 alternative transformation platforms, one which involves an air-gun based technique and another which involves DNA injection into sclerotia. Both techniques show great promise and have been validated using different constructs. This contribution is likely to serve the scientific community in the near future. Using these technologies we generated gene knockout constructs of 2 genes and have tested there effect on survival of the fungus at low temperature. With reference to the bR genes our results show that it has a significant effect on mycelial growth of the B. cinerea and the mutants have retarded development at extreme conditions of ionic stress, osmotic stress and low temperature. Another gene of unknown function, HP1 is still under analysis. An ortholog of the yeast cold-induced gene, CCH1 which encodes a calcium tunnel and was shown to be cold-induced in B. cinerea was recently cloned and used to complement yeast mutants and rescue them from cold-sensitivity. One of the significant findings of the microarray study involves a T2 ribonuclease which was validated to be cold-induced by qPCR analysis. This and other genes will serve for future studies. In the frame of the study we also screened a population of 631 natural B. cinerea isolates for development at low temperature and have identified several strains with much higher and lower capacity to develop at low temperature. These strains are likely to be used in the future as candidates for further functional analysis. The major conclusions from the above research point to specific targets of cold-induced genes which are likely to play a role in cold tolerance. One of the most significant observations from the microarray study is that low temperature does not induce ‘general stress response in B. cinerea, which is in agreement to its exceptional capacity to develop at low temperature. Due to the tragic murder of the Co-PI Maria R. Davis and GopiPodila on Feb. 2010 it is impossible to deliver their contribution to the research. The information of the PI is that they failed to deliver objective 4 and none of the information which relates to objective 3 has been delivered to the PI before the murder or in a visit to U. Alabama during June, 2010. Therefore, this report is based solely on the IS data.
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Rahman, Mohammad, Ahmed Ibrahim, and Riyadh Hindi. Bridge Decks: Mitigation of Cracking and Increased Durability—Phase III. Illinois Center for Transportation, December 2020. http://dx.doi.org/10.36501/0197-9191/20-022.
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Early-age cracking in concrete decks significantly reduces the service life of bridges. This report discusses the application of various concrete mixtures that include potential early mitigation ingredients. Large-scale (7 ft × 10 ft) experimental bridge prototypes with similar restraint conditions found in actual bridges were poured with different concrete mixtures to investigate mitigation techniques. Portland cement (control), expansive Type K cement, internally cured lightweight aggregate (LWA), shrinkage-reducing admixture (SRA), and gypsum mineral were investigated as mitigating ingredients. Seven concrete mixtures were prepared by using individual ingredients as well as a combination of different ingredients. The idea behind combining different mitigating techniques was to accumulate the combined benefit from individual mitigating materials. The combined Type K cement and LWA mixture showed higher concrete expansion compared with mixtures containing Portland cement, Type K cement, LWA, and SRA in the large-scale experimental deck. Extra water provided by LWA significantly enhanced the performance of Type K cement’s initial expansion as well as caused larger total shrinkage over the drying period. A combination of Type K cement and gypsum mineral showed insignificantly higher expansion compared with the individual Type K mixture. Overall, the experimental deck containing SRA showed the least total shrinkage compared with other mixtures. Finite-element modeling was performed to evaluate and predict concrete stress-strain behavior due to shrinkage in typical bridges. A parametric study using finite-element analysis was conducted by altering the structure of the experimental deck. More restraint from internal reinforcement, less girder spacing, larger girder flange width, and more restrictive support conditions increased the concrete tensile stress and led to potential cracking in the concrete deck.
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Shapira, Roni, Judith Grizzle, Nachman Paster, Mark Pines, and Chamindrani Mendis-Handagama. Novel Approach to Mycotoxin Detoxification in Farm Animals Using Probiotics Added to Feed Stuffs. United States Department of Agriculture, May 2010. http://dx.doi.org/10.32747/2010.7592115.bard.
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T-2 toxin, a toxic product belongs to the trichothecene mycotoxins, attracts major interest because of its severe detrimental effects on the health of human and farm animals. The occurrence of trichothecenes contamination is global and they are very resistant to physical or chemical detoxification techniques. Trichothecenes are absorbed in the small intestine into the blood stream. The hypothesis of this project was to develop a protecting system using probiotic bacteria that will express trichothecene 3-O-acetyltransferase (Tri101) that convert T-2 to a less toxic intermediate to reduce ingested levels in-situ. The major obstacle that we had faced during the project is the absence of stable and efficient expression vectors in probiotics. Most of the project period was invested to screen and isolate strong promoter to express high amounts of the detoxify enzyme on one hand and to stabilize the expression vector on the other hand. In order to estimate the detoxification capacity of the isolated promoters we had developed two very sensitive bioassays.The first system was based on Saccharomyces cerevisiae cells expressing the green fluorescent protein (GFP). Human liver cells proliferation was used as the second bioassay system.Using both systems we were able to prove actual detoxification on living cells by probiotic bacteria expressing Tri101. The first step was the isolation of already discovered strong promoters from lactic acid bacteria, cloning them downstream the Tri101 gene and transformed vectors to E. coli, a lactic acid bacteria strain Lactococcuslactis MG1363, and a probiotic strain of Lactobacillus casei. All plasmid constructs transformed to L. casei were unstable. The promoter designated lacA found to be the most efficient in reducing T-2 from the growth media of E. coli and L. lactis. A prompter library was generated from L. casei in order to isolate authentic probiotic promoters. Seven promoters were isolated, cloned downstream Tri101, transformed to bacteria and their detoxification capability was compared. One of those prompters, designated P201 showed a relatively high efficiency in detoxification. Sequence analysis of the promoter region of P201 and another promoter, P41, revealed the consensus region recognized by the sigma factor. We further attempted to isolate an inducible, strong promoter by comparing the protein profiles of L. casei grown in the presence of 0.3% bile salt (mimicking intestine conditions). Six spots that were consistently overexpressed in the presence of bile salts were isolated and identified. Their promoter reigns are now under investigation and characterization.
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Zhou, Ting, Roni Shapira, Peter Pauls, Nachman Paster, and Mark Pines. Biological Detoxification of the Mycotoxin Deoxynivalenol (DON) to Improve Safety of Animal Feed and Food. United States Department of Agriculture, July 2010. http://dx.doi.org/10.32747/2010.7613885.bard.
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The trichothecene deoxynivalenol (DON, vomitoxin), one of the most common mycotoxin contaminants of grains, is produced by members of the Fusarium genus. DON poses a health risk to consumers and impairs livestock performance because it causes feed refusal, nausea, vomiting, diarrhea, hemolytic effects and cellular injury. The occurrence of trichothecenes contamination is global and they are very resistant to physical or chemical detoxification techniques. Trichothecenes are absorbed in the small intestine into the blood stream. The overall objective of this project was to develop a protecting system using probiotic bacteria that will express trichothecene 3-O-acetyltransferase (Tri101) that convert T-2 to a less toxic intermediate to reduce ingested levels in-situ. The major obstacle that we had faced during the project is the absence of stable and efficient expression vectors in probiotics. Most of the project period was invested to screen and isolate strong promoter to express high amounts of the detoxify enzyme on one hand and to stabilize the expression vector on the other hand. In order to estimate the detoxification capacity of the isolated promoters we had developed two very sensitive bioassays.The first system was based on Saccharomyces cerevisiae cells expressing the green fluorescent protein (GFP). Human liver cells proliferation was used as the second bioassay system.Using both systems we were able to prove actual detoxification on living cells by probiotic bacteria expressing Tri101. The first step was the isolation of already discovered strong promoters from lactic acid bacteria, cloning them downstream the Tri101 gene and transformed vectors to E. coli, a lactic acid bacteria strain Lactococcuslactis MG1363, and a probiotic strain of Lactobacillus casei. All plasmid constructs transformed to L. casei were unstable. The promoter designated lacA found to be the most efficient in reducing T-2 from the growth media of E. coli and L. lactis. A prompter library was generated from L. casei in order to isolate authentic probiotic promoters. Seven promoters were isolated, cloned downstream Tri101, transformed to bacteria and their detoxification capability was compared. One of those prompters, designated P201 showed a relatively high efficiency in detoxification. Sequence analysis of the promoter region of P201 and another promoter, P41, revealed the consensus region recognized by the sigma factor. We further attempted to isolate an inducible, strong promoter by comparing the protein profiles of L. casei grown in the presence of 0.3% bile salt (mimicking intestine conditions). Six spots that were consistently overexpressed in the presence of bile salts were isolated and identified. Their promoter reigns are now under investigation and characterization.
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Barefoot, Susan F., Bonita A. Glatz, Nathan Gollop, and Thomas A. Hughes. Bacteriocin Markers for Propionibacteria Gene Transfer Systems. United States Department of Agriculture, June 2000. http://dx.doi.org/10.32747/2000.7573993.bard.
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The antibotulinal baceriocins, propionicin PLG-1 and jenseniin G., were the first to be identified, purified and characterized for the dairy propionibaceria and are produced by Propionibacterium thoenii P127 and P. thoenii/jensenii P126, respectively. Objectives of this project were to (a) produce polyclonal antibodies for detection, comparison and monitoring of propionicin PLG-1; (b) identify, clone and characterize the propionicin PLG-1 (plg-1) and jenseniin G (jnG) genes; and (3) develop gene transfer systems for dairy propionibacteria using them as models. Polyclonal antibodies for detection, comparison and monitoring of propionicin PLG-1 were produced in rabbits. Anti-PLG-1 antiserum had high titers (256,000 to 512,000), neutralized PLG-1 activity, and detected purified PLG-1 at 0.10 mg/ml (indirect ELISA) and 0.033 mg/ml (competitive indirect ELISA). Thirty-nine of 158 strains (most P. thoenii or P. jensenii) yielded cross-reacting material; four strains of P. thoenii, including two previously unidentified bacteriocin producers, showed biological activity. Eight propionicin-negative P127 mutants produced neither ELISA response nor biological activity. Western blot analyses of supernates detected a PLG-1 band at 9.1 kDa and two additional protein bands with apparent molecular weights of 16.2 and 27.5 kDa. PLG-1 polyclonal antibodies were used for detection of jenseniin G. PLG-1 antibodies neutralized jenseniin G activity and detected a jenseniin G-sized, 3.5 kDa peptide. Preliminary immunoprecipitation of crude preparations with PLG-1 antibodies yielded three proteins including an active 3-4 kDa band. Propionicin PLG-1 antibodies were used to screen a P. jensenii/thoenii P126 genomic expression library. Complete sequencing of a cloned insert identified by PLG-1 antibodies revealed a putative response regulator, transport protein, transmembrane protein and an open reading frame (ORF) potentially encoding jenseniin G. PCR cloning of the putative plg-1 gene yielded a 1,100 bp fragment with a 355 bp ORF encoding 118 amino acids; the deduced N-terminus was similar to the known PLG-1 N-terminus. The 118 amino acid sequence deduced from the putative plg-1 gene was larger than PLG-1 possibly due to post-translational processing. The product of the putative plg-1 gene had a calculated molecular weight of 12.8 kDa, a pI of 11.7, 14 negatively charged residues (Asp+Glu) and 24 positively charged residues (Arg+Lys). The putative plg-1 gene was expressed as an inducible fusion protein with a six-histidine residue tag. Metal affinity chromatography of the fused protein yielded a homogeneous product. The fused purified protein sequence matched the deduced putative plg-1 gene sequence. The data preliminarily suggest that both the plg-1 and jnG genes have been identified and cloned. Demonstrating that antibodies can be produced for propionicin PLG-1 and that those antibodies can be used to detect, monitor and compare activity throughout growth and purification was an important step towards monitoring PLG-1 concentrations in food systems. The unexpected but fortunate cross-reactivity of PLG-1 antibodies with jenseniin G led to selective recovery of jenseniin G by immunoprecipitation. Further refinement of this separation technique could lead to powerful affinity methods for rapid, specific separation of the two bacteriocins and thus facilitate their availability for industrial or pharmaceutical uses. Preliminary identification of genes encoding the two dairy propionibacteria bacteriocins must be confirmed; further analysis will provide means for understanding how they work, for increasing their production and for manipulating the peptides to increase their target species. Further development of these systems would contribute to basic knowledge about dairy propionibacteria and has potential for improving other industrially significant characteristics.
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis, and Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
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One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.
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Shpigel, Nahum, Raul Barletta, Ilan Rosenshine, and Marcelo Chaffer. Identification and characterization of Mycobacterium paratuberculosis virulence genes expressed in vivo by negative selection. United States Department of Agriculture, January 2004. http://dx.doi.org/10.32747/2004.7696510.bard.
Full textAbstract:
Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of a severe inflammatory bowel disease (IBD) in ruminants, known as Johne’s disease or paratuberculosis. Johne’s disease is considered to be one of the most serious diseases affecting dairy cattle both in Israel and worldwide. Heavy economic losses are incurred by dairy farmers due to the severe effect of subclinical infection on milk production, fertility, lower disease resistance and early culling. Its influence in the United States alone is staggering, causing an estimated loss of $1.5 billion to the agriculture industry every year. Isolation of MAP from intestinal tissue and blood of Crohn's patients has lead to concern that it plays a potential pathogenic role in promoting human IDB including Crohn’s disease. There is great concern following the identification of the organism in animal products and shedding of the organism to the environment by subclinically infected animals. Little is known about the molecular basis for MAP virulence. The goal of the original proposed research was to identify MAP genes that are required for the critical stage of initial infection and colonization of ruminants’ intestine by MAP. We proposed to develop and use signature tag mutagenesis (STM) screen to find MAP genes that are specifically required for survival in ruminants upon experimental infection. This research projected was approved as one-year feasibility study to prove the ability of the research team to establish the animal model for mutant screening and alternative in-vitro cell systems. In Israel, neonatal goat kids were repeatedly inoculated with either one of the following organisms; MAP K-10 strain and three transposon mutants of K-10 which were produced and screened by the US PI. Six months after the commencement of inoculation we have necropsied the goats and taken multiple tissue samples from the jejunum, ileum and mesenteric lymph nodes. Both PCR and histopathology analysis indicated on efficient MAP colonization of all the inoculated animals. We have established several systems in the Israeli PI’s laboratory; these include using IS900 PCR for the identification of MAP and using HSP65-based PCR for the differentiation between MAV and MAP. We used Southern blot analysis for the differentiation among transposon mutants of K-10. In addition the Israeli PI has set up a panel of in-vitro screening systems for MAP mutants. These include assays to test adhesion, phagocytosis and survival of MAP to/within macrophages, assays that determine the rate of MAPinduced apoptosis of macrophages and MAP-induced NO production by macrophages, and assays testing the interference with T cell ã Interferon production and T cell proliferation by MAP infected macrophages (macrophage studies were done in BoMac and RAW cell lines, mouse peritoneal macrophages and bovine peripheral blood monocytes derived macrophages, respectively). All partners involved in this project feel that we are currently on track with this novel, highly challenging and ambitious research project. We have managed to establish the above described research systems that will clearly enable us to achieve the original proposed scientific objectives. We have proven ourselves as excellent collaborative groups with very high levels of complementary expertise. The Israeli groups were very fortunate to work with the US group and in a very short time period to master numerous techniques in the field of Mycobacterium research. The Israeli group has proven its ability to run this complicated animal model. This research, if continued, may elucidate new and basic aspects related to the pathogenesis MAP. In addition the work may identify new targets for vaccine and drug development. Considering the possibility that MAP might be a cause of human Crohn’s disease, better understanding of virulence mechanisms of this organism might also be of public health interest as well.
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Tire Experimental Characterization Using Contactless Measurement Methods. SAE International, August 2021. http://dx.doi.org/10.4271/2021-01-1114.
Full textAbstract:
In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.