abstract: Student pilots are the future of aviation and one of the biggest problems that they face as new pilots is fatigue. The survey was sent out asking if student pilots were fatigued, if they attribute flight training, school work, work outside of school, and social obligations to their sleep loss, and how they spend their time on those activities. The survey was given to aviation students at Arizona State University (ASU) Polytechnic Campus. ASU student pilots were found to be fatigued through a single sample t-test. Other t-tests were done on each of the questions that asked student pilots how flight training, school work, work outside of school and social obligations affect their sleep loss. Flight training and school were found to be contributing to student pilots sleep loss. Work outside of school and social obligations were found to not be contributing to student pilots sleep loss. It was found that student pilots’ tendency to use a planner or calendar was found to not be significant. Along with this planning through the week when they will do assignments or study for exams was also not found to be significant. Students making lists of assignments and when they are due was also found to not be significant. The t-test also found that student pilots are neutral on the topic of whether good time management skills would help increase the amount of sleep that they get. / Dissertation/Thesis / Masters Thesis Technology 2019

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Thesis (M.S.E.S.)--University of Toledo, 2005. / Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science degree in Exercise Science." Bibliography: leaves 71-87.

Material failures in heat exchangers are often closely tied to events associated with the conditions of service and operating parameters. These events can generally be attributed to adverse load application and higher than optimum operating temperatures that could lead to changes in the microstructure of the materials and fatigue failure of the component. However, fatigue failure in heat exchangers is usually associated with the presence of a biaxial stress condition. Two nonparallel forces create a two-dimensional stress field at the free surface of the structural element where the process and mechanism of fatigue failure normally initiate. An experimental investigation was conduct6d to evaluate the biaxial fatigue behavior of commercially pure titanium Ti-50A (Grade 2) and low-alloy titanium Ti-Code 12 (Grade 12) heat exchanger materials. The biaxial state of stress was composed of an axial stress and a superimposed torsional stress, applied in a thin-wall tubular specimen machined from titanium tubing. Torsional stress was applied independently using a torsion machine and a torque fixer assembly devised as part of this study. After applying the desired torsion, the torsionally stressed specimen was mounted on a closed-loop electrohydraulic machine for the application of axial cyclic loading. A minimum of four tests were conducted for each of three alternating stress levels at both high and low torsional stresses. The biaxial fatigue test under load control condition was done under fully reversed cycles equivalent to a biaxiality ratio of -1. These test parameters were determined from an analytical formulation based on Mohr's circle. The results are presented in terms of the various measured or calculated quantities versus number of cycles to fracture. Biaxial fatigue curves were drawn through the experimental points corresponding to Weibull's mean life criterion. The four data points exhibit scatter that appears to be related to the applied stress amplitude. It was also found that a correlation exists between the magnitude of applied cyclic biaxial stress and fatigue life to failure. In addition, the results have been discussed taking existing failure criteria into account. / Graduation date: 1985

In the past riveting was commonly used for connecting steel structures, such as bridges. These fasteners usually develop a low and unreliable level of pretension such that the joints are assumed to behave like bearing type connections. Under cyclic loading, and depending on the stress concentration around the fastener holes, fatigue failure can occur at nominal stresses significantly lower than in members with no stress concentration. The current design standards account for this by calculating the stress range on the net section and using fatigue category B and D to assess the fatigue life for bolted and riveted details respectively. The net area used for the calculation of the stress range is based on the procedure proposed by Cochrane (the s2/4g rule), which is adequate shear type failure. Tests have shown, however, that the Cochrane approach does not apply for fatigue failure since rupture does not take place in a ductile shear mode. An investigation into the effect of connection size and hole pattern on the fatigue resistance of built-up I section to gusset plate connections was carried out. A design equation that considers the connection size and hole layout on the stress concentration factor is proposed. An appropriate fatigue category for these members is also recommended. / Structural Engineering

Thesis (Ph. D.)--University of North Carolina at Greensboro, 2006. / Title from PDF title page screen. Advisor: Sandra Shultz; submitted to the School of Health and Human Performance. Includes bibliographical references (p. 104-113).

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss&rft%5Fval%5Ffmt=info:ofi/fmt:kev:mtx:dissertation&rft%5Fdat=xri:pqdiss:MQ99279

Fatigue cracking is one of the fundamental distresses that occur in the life of a Hot Mix Asphalt Concrete (HMAC) pavement. This load induced distress leads to structural collapse of the entire pavement ultimately and can only be remedied by rehabilitation. There is the need, therefore, for a total understanding of the phenomenon to be able to counter its occurrence. The fatigue resistance of hot mix asphalt concrete (HMAC) has been estimated using approaches ranging from empirical methods to mechanistic-empirical methods to purely mechanistic methods. A continuum mechanics based approach called the Calibrated Mechanistic with Surface Energy (CMSE) measurements was developed at Texas A&M University and recommended after comparison with other approaches in predicting fatigue lives of two Texas HMAC mixtures. The CMSE approach which includes fundamental material properties such as fracture, aging, healing, and anisotropy has been shown to effectively model the parameters that affect the performance of HMAC pavements exposed to repetitive traffic loads. Polymer modified asphalt (PMA) improves pavement performance by providing additional resistance to the primary distresses in flexible pavements, including permanent deformation or rutting, thermal cracking, and fatigue cracking. In this research, the CMSE approach was utilized to estimate the fatigue resistance of HMAC fabricated with asphalts modified with Styrene-butadiene-Styrene (SBS) co-block polymer. These HMAC mixtures were fabricated from materials used on three different road sections in Texas and one test pavement in Minnesota. The CMSE approach was validated as an effective approach for estimating the fatigue resistance of HMAC mixtures with PMA. The effect of oxidative aging on the fatigue resistance of the HMAC mixtures was also verified. Oxidative aging of the mixtures resulted in a corresponding decrease in mixture fatigue resistance. In addition, for two HMAC mixtures with the same binder content and aggregate gradation, the mixture with the softer of the two Performance Grade (PG) binders exhibited greater fatigue resistance. The use of the Utility Theory revealed the possible effects of aggregate geometric properties on the HMAC mixture properties and consequently on their fatigue resistance.

Since a significantly greater percentage of body weight is supported by the non-paretic limb following stroke, a greater amount of fatigue may be present during daily activities. This may affect the ability of these individuals to maintain a stable upright posture. The presence of falls following a stroke has been attributed in part to this asymmetrical stance post-stroke. Therefore the purpose of this study was to assess the effect of quadriceps muscle fatigue on bi-pedal posture in individuals who had a stroke and an age-matched control group. Although individuals after stroke displayed greater postural sway under the paretic limb than the non-paretic limb or control subjects, results of this study show that sustaining an isometric knee extension of the non-paretic limb induces changes in postural control for individuals after stroke, but that these changes do not markedly differ from those of healthy age-matched controls.