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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.
81

Sinsistral high strain in the Coast Mountains near Bella Coola, West Central British Columbia

Demerse, Deirdre K. 05 1900 (has links)
The Bella Coola area geographically straddles two zones of known Early to mid-Cretaceous sinistral ductile strain; the Grenville, Kitkatla, and Principe-Laredo shear zones to the northwest located near Prince Rupert, B.C., and the Tchaikazan fault system to the southeast. At the latitude of Bella Coola in west-central B.C., the Pootlass High Strain Zone (PHSZ) is a ductile, subvertical, shear zone system at least 2 km wide and at least 30 km long. The purpose of this study is to determine the age, kinematics, and tectonic significance of the PHSZ, and to investigate whether or not it was active as a kinematic link to Early to mid-Cretaceous sinistral ductile strain zones in the western Canadian Cordillera. This thesis reports recent observations from field mapping and new geochronological, microstructural, and petrological data, from which the PHSZ is characterized and placed into a regional tectonic framework. U-Pb and 40Ar/39Ar isotopic geochronology indicate that regionally extensive, southwest-vergent folding in the PHSZ area was active prior to 114 Ma and persisted until at least 73 Ma. High-temperature, ductile, sinistral non-coaxial strain in the PHSZ was accommodated between 76 (or earlier) and 62 Ma. Localization of high strain is associated with the emplacement of plutonic rock and abundant intrusive sills, which likely acted as a strain-softening mechanism. L-tectonites within the deformed plutonic rocks attest to the weakness of the rocks during deformation and support syn-kinematic magmatism. Geothermometric and petrological data suggest that deformation occurred at temperatures of 537 to 731°C and at crustal depths of —23 km. The PHSZ is interpreted to be kinematically related to the Talchako Fault to the east, which was active as a sinistral mylonitic shear zone between 70 and 65 Ma. A kinematic relationship between the PHSZ and the Grenville, Kitkatla and Principe-Laredo shear zones near Prince Rupert imply a protracted history of sinistral transpression in the Coast Mountains of British Columbia that persisted in the Bella Coola region through Late Cretaceous time.
82

Effects of Prestrain on the Strain Rate Sensitivity of AA5754 Sheet

Wowk, DIANE 27 September 2008 (has links)
With the focus of the automotive industry on decreasing vehicle weight and improving fuel efficiency, aluminum is being used for structural components in automobiles. Given the high strain rates associated with vehicle impact, it is necessary to understand the rate sensitivity of any potential alloy (eg. AA5754) in order to accurately predict deformation behaviour. Furthermore, the magnitude and strain path associated with the residual strains remaining after forming of the component also play a major role in how the material will behave. It has been found that AA5754 sheet exhibits negative rate sensitivity up to a strain rate of 0.1/s, and positive strain rate sensitivity at strain rates between 0.1/s and 1500/s. Increasing the strain rate also has the effect of increasing the yield stress as well as the ductility. When a strain path change is involved between the prestrain stage and subsequent uniaxial loading, it has the effect of reducing the rate sensitivity of the material as well as reducing the overall flow stress. A rate-sensitive adaptation of the Voce material model was successfully implemented in LS-DYNA and used to predict the response of AA5754 sheet in bending for applied strain rates of 0.001/s and 0.1/s. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-09-23 20:11:30.829
83

Extension of a finite element model to 2D for the prediction of adiabatic shear bands

Delorme, Jeffrey 21 September 2012 (has links)
Failure of metals under impact loading is known to occur through the formation of adiabatic shear bands (ASBs). ASBs appear in materials as evidence of damage, and are known to be sites for material failure. General purpose plasticity models fail to predict the phenomenon of ASB formation. The present research validates and extends a model developed at the University of Manitoba by Feng and Bassim to predict damage due to ASBs. Parameters for the Feng and Bassim model are determined experimentally using a direct impact pressure bar to impact specimens at temperatures of 20-500oC and strain rates of 500-3000/s. A direct impact experiment is simulated in ANSYS using the model and fitted parameters. The results of the simulation show localized temperature rise and predict failure at the same locations as those observed experimentally. Nominal strain to failure is approximately 40-50% for a specimen impacted at 38 kg-m/s.
84

Extension of a finite element model to 2D for the prediction of adiabatic shear bands

Delorme, Jeffrey 21 September 2012 (has links)
Failure of metals under impact loading is known to occur through the formation of adiabatic shear bands (ASBs). ASBs appear in materials as evidence of damage, and are known to be sites for material failure. General purpose plasticity models fail to predict the phenomenon of ASB formation. The present research validates and extends a model developed at the University of Manitoba by Feng and Bassim to predict damage due to ASBs. Parameters for the Feng and Bassim model are determined experimentally using a direct impact pressure bar to impact specimens at temperatures of 20-500oC and strain rates of 500-3000/s. A direct impact experiment is simulated in ANSYS using the model and fitted parameters. The results of the simulation show localized temperature rise and predict failure at the same locations as those observed experimentally. Nominal strain to failure is approximately 40-50% for a specimen impacted at 38 kg-m/s.
85

Sinsistral high strain in the Coast Mountains near Bella Coola, West Central British Columbia

Demerse, Deirdre K. 05 1900 (has links)
The Bella Coola area geographically straddles two zones of known Early to mid-Cretaceous sinistral ductile strain; the Grenville, Kitkatla, and Principe-Laredo shear zones to the northwest located near Prince Rupert, B.C., and the Tchaikazan fault system to the southeast. At the latitude of Bella Coola in west-central B.C., the Pootlass High Strain Zone (PHSZ) is a ductile, subvertical, shear zone system at least 2 km wide and at least 30 km long. The purpose of this study is to determine the age, kinematics, and tectonic significance of the PHSZ, and to investigate whether or not it was active as a kinematic link to Early to mid-Cretaceous sinistral ductile strain zones in the western Canadian Cordillera. This thesis reports recent observations from field mapping and new geochronological, microstructural, and petrological data, from which the PHSZ is characterized and placed into a regional tectonic framework. U-Pb and 40Ar/39Ar isotopic geochronology indicate that regionally extensive, southwest-vergent folding in the PHSZ area was active prior to 114 Ma and persisted until at least 73 Ma. High-temperature, ductile, sinistral non-coaxial strain in the PHSZ was accommodated between 76 (or earlier) and 62 Ma. Localization of high strain is associated with the emplacement of plutonic rock and abundant intrusive sills, which likely acted as a strain-softening mechanism. L-tectonites within the deformed plutonic rocks attest to the weakness of the rocks during deformation and support syn-kinematic magmatism. Geothermometric and petrological data suggest that deformation occurred at temperatures of 537 to 731°C and at crustal depths of —23 km. The PHSZ is interpreted to be kinematically related to the Talchako Fault to the east, which was active as a sinistral mylonitic shear zone between 70 and 65 Ma. A kinematic relationship between the PHSZ and the Grenville, Kitkatla and Principe-Laredo shear zones near Prince Rupert imply a protracted history of sinistral transpression in the Coast Mountains of British Columbia that persisted in the Bella Coola region through Late Cretaceous time.
86

Enhancing the Coping Skills of Submariners: An Evaluation of the Effectiveness of Skills Based Stress Management Training

cindy@macknsons.com, Lucinda Samantha McDougall January 2007 (has links)
Submariners are exposed to a unique range of stressors, such as cramped living conditions, lack of privacy, extended periods of isolation and confinement, lack of sunlight, and constant threat. These are in addition to those associated with the military environment. Due to the dangers of the work and potential for disastrous consequences, submariners need to be emotionally stable and possess good coping skills. Previous research on the Royal Australian Navy (RAN) Submarine Service indicated a need for further support to improve individual coping and organisational outcomes. Based on this research, current attitudes towards Submarine Service were examined, such as views on working hours, job demands, training and preparation, and being a submariner. Going one step further, this study investigated the effectiveness of a multimodal cognitive behavioural workplace stress management intervention with RAN submariners. A quasi-experimental design was employed and the eight-session intervention was conducted with operational submariners whilst they were working on shore. Work outcomes measured included job satisfaction, job performance, and sickbay attendance, and psychological outcomes examined were stress and strain symptoms, depression, anxiety, coping resources, health and general wellbeing. These outcomes were assessed through self-report both at sea and on shore. Stress symptoms, vocational strain, interpersonal strain, and role overload strain all decreased after the intervention, and use of social support as a coping resource and confidence in job performance both increased. Unfortunately, however, these changes were not sustained in the sea-going environment. These results are discussed in light of previous research, and recommendations for the organisation and for future research are outlined.
87

Meta-uncertainty and resilience with applications in intelligence analysis

Schenk, Jason Robert. January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007.
88

The design of skin friction gages for measurements in high-speed, short-duration flows /

Busic, John F., January 1992 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaf 113). Also available via the Internet.
89

Analysis of structural development during superdrawing of poly(ethylene terephthalate) fibers

Jain, Vibhor January 2009 (has links)
Thesis (M. S.)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Wang, Youjiang; Committee Co-Chair: Jacob, K.I.; Committee Member: Aneja, A.P.; Committee Member: Garmestani, Hamid; Committee Member: Thio, Yonathan S.; Committee Member: Yao, Donggang
90

Work-related complaints in the upper extremity prevention and treatment /

Meijer, Eline Maria. January 2006 (has links)
Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

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