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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Floating head skin friction gage measurements in supersonic flows /

Lattimer, Brian Y., January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 122-123). Also available via the Internet.
182

High temperature fiber optic strain sensing /

Koob, Christopher E., January 1991 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 91-93). Also available via the Internet.
183

Development of a transparent indenter measurement system and indentation analysis for material mechanical property evaluation

Feng, Chuanyu. January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains x, 104 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 97-100).
184

Portable transparent indenter instrumentation for material surface characterization

Noriega Motta, Julio Amilcar. January 2006 (has links)
Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiii, 105 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 97-98).
185

Análise da distribuição de cargas e das forças entre asseno e encosto, na postura sentada adequada

Resende, Fernanda de Lima e Sá [UNESP] 11 August 2006 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-11Bitstream added on 2014-06-13T20:37:39Z : No. of bitstreams: 1 resende_fls_me_guara.pdf: 781042 bytes, checksum: 90a752d449437b2098cb5b1a50b2cae7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi estudar a distribuição das cargas no sistema cadeira plataforma de força (C-PF) e verificar se há correlação entre as forças medidas no assento e encosto, na postura sentada adequada. Participaram 38 voluntários, classificados pelo biótipo (32 mulheres e 6 homens): idade média de 43,92 anos, estatura média de 1,60 m e peso corporal médio de 65,10 kgf. Uma cadeira, com células de carga nas partes anterior e posterior do assento e no encosto, e uma plataforma de força mediram a distribuição do peso corporal. Estabeleceram-se várias correlações entre as variáveis (peso corporal, altura, idade, e índice de massa corporal) e as cargas medidas e entre as próprias forças adquiridas. Uma das correlações determinou uma relação entre a força total no assento e a força medida no encosto. A distribuição do peso corporal observada foi: 20,04% na plataforma de força; 45,33% e 30,43%, nas partes anterior e posterior do assento, respectivamente; e 4,20% no encosto. Não houve diferenças estatísticas significativas na comparação das médias dos valores da distribuição do peso corporal tanto entre os sexos como entre os biótipos. Porém, como há diferenças na forma corporal de acordo com os sexos e com os biótipos, houve certa diferença nos valores das forças medidas, no sistema C-PF. / The aim of this study was to study the load distribution in chair-force plate system (CFP) and to verify if there is correlation between measured seat and backrest forces in the adequate sitting posture. 38 volunteers participated of the study, classifieds according to physical types (32 female and 6 male): mean age of 43,92 years old, mean height of 1,60 m and mean body weight of 65,10 kgf. An instrumented office chair with load cells in the anterior and posterior portions of the seat and backrest and a force plate were used to measure the forces and body weight distribution in C-FP system. This study was established many correlations among some variables (body weight, height, age and body mass index) and the measured loads and among the acquired forces. One of these correlations determined a relation among total force measured on seat and acquired force on lumbar backrest. The body weight distribution observed in the C-FP system was: 20,04% in the force plate, 45,33% and 30,43% in the anterior and posterior portions of the seat respectively, and 4,20% in the backrest. There were no statistics significant differences in comparison of values weight distribution averages as between gender as between physical patterns. But, there are some differences in the body shape according to gender and physical patterns, it there was some difference in the values of acquired forces in the C-FP system.
186

LABORATORY INVESTIGATION OF COAL PERMEABILITY UNDER REPLICATED IN SITU STRESS REGIME

Mitra, Abhijit 01 May 2010 (has links)
The cleat permeability of coal, a key to the success of any coalbed methane (CBM) recovery operation, is a dynamic parameter impacted by changes in effective stress and desorption-induced "matrix shrinkage". Most commonly-used theoretical models developed to predict CBM production as a result of permeability changes are based on the assumption that the deformation of a depleting coalbed is limited to the vertical direction; that is, the coal is under uniaxial strain conditions. However, most laboratory studies completed to estimate the changes in coal permeability have used triaxial state of stress, thus violating the underlying principles of the models. An experimental study was, therefore, undertaken to estimate the permeability variation of coal with a decrease in pore pressure under replicated in situ conditions where flow through coal, held under uniaxial strain conditions, was measured. Three samples were tested, one from the San Juan basin and the other two from the Illinois basin. The experimental results showed that, under uniaxial strain conditions, decreasing pore pressure resulted in a significant decrease in horizontal stress and increased permeability. The permeability increased non-linearly with decreasing pore pressure, with a small increase in the high pressure range, which increased progressively as the pressure dropped below a certain value. The experimental results were used to validate two theoretical models, namely the Palmer and Mansoori and Shi and Durucan, commonly used to project permeability variation with continued production. The models failed to provide good agreement with the experimental results below 300 psi, suggesting a shortcoming in the modeling philosophy. Although the measured permeability and stress changes were in qualitative agreement with the modeling results, both models predicted negative horizontal stresses at low pore pressures for one coal type, which was not supported by experimental results. The sorption-induced strain was also found to be significantly higher in the low pore pressure range, clearly suggesting a direct relationship between the sorption-induced strain and permeability. Moreover, the increase in permeability was different for the three coal types tested, with the largest increase for the core taken from maximum depth. Finally, a gradual increase in the logarithm of permeability was measured with reduction in horizontal stress. These results suggest a distinct advantage for deeper coals, which have generated limited interest to date, primarily due to the low initial permeability. Extending the deformation of a cylindrical rock sample loaded axially, a hypothesis was developed where coal undergoes maximum deformation at the middle of its length. Using this hypothesis, permeability variation with decreasing pore pressure was estimated and the established trend was used to modify one of the existing models. The agreement between laboratory results and the modified model showed definite promise for improving permeability projection capability.
187

Graphene characterization and device fabrication: doping analysis, strains engineering towards terahertz radiation

Wang, Xuanye 02 November 2017 (has links)
As one of the most promising two-dimensional materials, graphene’s outstanding electrical, mechanical and optical properties have made many new devices possible. Its ultra-thin thickness makes both the fabrication and characterization of graphene-based device challenging. In my thesis, I will discuss different approaches to fabricate and characterize graphene devices for the use in transport and THz radiation devices, as well as strain engineering. These approaches could be potentially used to produce next generation electrical devices, photonics devices and generate ultra-high pseudomagnetic fields. To analyze graphene’s quality, I use multi-variable Raman spectroscopy for identifying graphene’s defect density, strain and doping. A case study of strain redistribution on a silicon dioxide grating with sub-diffraction limit resolution of the strain variation is presented, where atomic force microscopy and Raman spectroscopy are applied for characterization. The strain redistribution is used to determine the strain dependent friction between graphene and the substrate. This work has also lead to more precise determination of the strain and shear response using the 2D phonon band. Improvements of the electrical property of graphene is achieved by using graphene encapsulated between atomically flat hBN layers as well as tuning surface hydrophobicity via substrate salinization. This also provides an improved method to optically determine charge density in graphene with order of magnitude enhancement in sensitivity.
188

Gender and Juvenile Drug Abuse: A General Strain Theory Perspective

Grothoff, Garrett E. 01 December 2010 (has links)
This study is a partial test of Robert Agnew's (2006) General Strain Theory. The sample consists of 39,879 juveniles between the ages of 10 and 17 from a metropolitan area in Texas with more than 5 million people. Logistic regression is used to determine the effect that living situation produces on drug offenders, drug recidivists, and juvenile court case outcome controlling for race, abuse, sex, and mental health problems. Gender-specific analysis is used to test Agnew and Broidy's (2001) hypothesis that girls and boys react differently to strain. Results show partial support for the influence of strained living situation on drug offenders, drug recidivists, and case outcome. Support was found for the hypothesis that boys and girls experiences with strain differs.
189

MODIFICATION OF A CURRENT COALBED METHANE PERMEABILITY MODEL FOR HORIZONTAL STRAIN ONLY

Schrader, Sawyer David 01 August 2018 (has links)
Cleat permeability of coal is the most critical parameter affecting the amount of production from a coalbed methane (CBM) reservoir. As a result, there have been many studies about how cleat permeability changes over the life of a reservoir, leading to the development over time of several different permeability models. Most permeability models used today consider volumetric strain as an input parameter; however, permeability is impacted primarily by the increase in cleat aperture, resulting from matrix shrinkage in the horizontal direction. Recent work has shown that coal exhibits transverse isotropy, with total strain in the vertical direction being significantly higher than either horizontal direction. Hence, the inclusion of vertical strain through use of the volumetric strain parameter could be predicting inaccurate permeability variation results. The objective of this study was to determine the difference in permeability modeling with volumetric strain compared to permeability modeling with only horizontal strain, and assess the degree to which different parameters affect results from modeling using only horizontal strain. Experimental results showed that matrix strain remained consistent with transversely isotropic results of previous works. When included into the Palmer and Mansoori (P&M) permeability model, modeling results showed that permeability with horizontal strain is significantly lower than that with volumetric strain. The three unmeasured parameters in the Palmer and Mansoori permeability model have a major effect on the final results and need to be history matched in order to improve the level of accuracy in their estimation.
190

Parental Incarceration: Does Having Minor Children Have an Effect on Recidivism?

January 2016 (has links)
abstract: Many parents are incarcerated, and most are eventually released. Parents that have to return home from prison may encounter difficulties adjusting to being a parent on the outside. Two competing criminological theories – social control and strain – build the framework for two pathways after release from prison – desistance or recidivism. The principal question of this study examines how being a parent to a minor child has an effect on the reentry pathways, and an interaction between being a parent and gender tests the differences between mothers and fathers. Existing studies have produced mixed results with some studies suggesting that minor children are a protective factor, and some suggesting the struggles of returning parents. Research has also shown that incarcerated mothers and fathers experience their incarceration differently, and it is surmised that this would have an impact on their reentry. Data used in this study were obtained through structured interviews with 952 inmates housed in the Arizona Department of Corrections in 2010 (n= 517 males (54%); n= 435 females (46%)). Logistic regression models show that having at least one minor child does not significantly impact the reentry outcomes for parents as compared to nonparents. In addition, the interaction between minor children and gender was also not significant – there were no differences between mothers and fathers. The statistically insignificant findings most likely show the cancelling effects of two distinct pathways for reentry. Implications of the findings are discussed below. / Dissertation/Thesis / Masters Thesis Criminology and Criminal Justice 2016

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