Driver fatigue is responsible for up to 30% of fatal car accidents. This issue has been addressed by many scholars in order to save thousands of lives and reduce many costs. The goal of this work is to reduce the number of car accidents caused by mental fatigue or drowsiness. In order to achieve this goal, we propose a personalized Bayesian Network (BN) to detect driver’s fatigue. The detection of driver fatigue is enhanced by combining data that reflects the driver’s performance with context-aware information. The parameters of the system are the angular velocity of the steering wheel, the pressure applied to the gas and brake pedals, the grip force on the steering wheel, weather conditions, current traffic, and time of day. The aforementioned parameters of the network are updated on a regular basis, which makes fatigue detection more reliable. Besides, these parameters allow the system to detect a driver’s fatigue through driving performance which is both individualized and context aware. In our experiment, subjects drove a driving simulator game during six sessions, for a total of one hour. After each session, every subject used the Karolinska Sleepiness Scale (KSS) to rate her fatigue’s level. The system was trained on the data collected separately from each user, allowing BN to be personalized for each subject. The proposed system showed an average accuracy of 96%, and ability to overcome the issue of individual differences and uncertainties which are involved in fatigue detection process.

Cette étude par éléments finis se propose d estimer la tenue en Fatigue de Contact de Roulement (FCR) d'une roue ferroviaire. La première partie de la thèse présente une analyse critique des approches de la littérature consacrées aux différents aspects du problème de FCR. La deuxième partie porte sur la modélisation bidimensionnelle d'une roue ferroviaire, comportant un défaut circulaire, et soumise à une pression de contact hertzien en mouvement. L'endommagement est quantifié par un paramètre de fatigue basé sur la densité d'énergie et la notion de plan critique. La durée de vie est calculée à l'aide d une loi utilisant les paramètres de fatigue oligocyclique. On montre que la technique du submodeling est un outil efficace permettant de réduire le temps de calcul CPU. Le troisième chapitre est une étude paramétrique de l'influence sur la durée de vie, du niveau de chargement, de la profondeur, de la nature et de la taille des défauts. Les résultats montrent que le plan critique d amorçage de fissure est parallèle à la surface de contact lorsque le mode I domine¡; il s'en écarte quand le mode II est prépondérant. Le quatrième chapitre porte sur l'influence des chargements à amplitudes variables ainsi que celle du frottement. On montre l effet bénéfique d une surcharge sur la durée de vie à l'amorçage de fissure. L'incidence néfaste du coefficient de frottement sur la durée de vie est mise en évidence dans le cas d'une roue avec et sans défaut. Enfin, la dernière partie de ce travail aborde les effets d'inertie dans le cas de la FCR. La durée de vie est surestimée dans le cas statique et diminue en dynamique avec la vitesse de roulement et le niveau de chargement / This study by finites elements proposes to estimate the Rolling Contact Fatigue (RCF) strength of a railway wheel. The first part of the thesis presents a critical analysis of the approaches of the literature relatives to the various aspects of the problem of RCF. The second part relates to the two-dimensional modeling of a railway wheel, consist a defect circular, and subjected to a moving hertzian contact pressure .The damage is quantified by a Fatigue Parameter (FP) based on the density of energy and the concept of critical plan. The lifetime is calculated using a law consist of the parameters of low-cycle fatigue. It is shown that the technique of the submodeling is an effective tool to reduce the computing time CPU. The third chapter is a parametric study about the influence over the lifetime, of the loading level, the defect depth, the nature and the size of the defects. The results show that the critical plan of crack initiation is parallel to the contact surface when mode I dominate; it deviates when mode II is dominating. The fourth chapter relates to the influence of the loadings with variable amplitudes and that of friction. We show the beneficial effect of an overload over the lifetime to crack initiation. The harmful incidence of the coefficient of friction over the lifetime is highlighted in the case of a wheel with and without defect. Finally, the last part of this work approaches the effects of inertia in the case of the RCF. The lifetime is over-estimated in the static case and decreases in dynamics with the rolling speed and the loading level

High frequency corrosion fatigue crack propagation behavior of AISI 316L stainless steel was studied in 1M NaCl and 1M NaCl + 0.01M Na₂S₂O₃, under various anodically and cathodically polarized potentials, and dessicated air at 22°C and 1 atmosphere pressure. Constant load amplitude fracture mechanics techniques employing single edge notch specimens were used to assess the fatigue crack growth rate in the various environments. Unique specimen preparation procedures were developed which allowed near-threshold behaviors to be studied under gradually rising crack tip stress intensity conditions. Polarization studies showed that the presence of thiosulphate catalyzed the dissolution of stainless steel in low pH solutions(pH~1), due to reduction of thiosulphate species to H₂S, but had no effect in the near neutral solutions. Fatigue tests conducted in the neutral NaCl + Na₂S₂O₃ solution at cathodic potentials showed that the presence of thiosulphate had an insignificant effect. This indicated that high frequency fatigue produces efficient exchange of bulk solution with the crack tip environment, which prevented the lowering of pH in the crack by hydrolysis effects and prevented reduction of thiosulphate to H₂S. Fatigue crack retardation phenomena were very pronounced in the near-threshold regions in most of the fatigue tests. The cause of this retardation was attributed mainly to the surface-roughness- induced crack closure effect, which reduced the effective crack tip cyclic stress intensity ΔKth to a lower level. This closure effect only predominated in the near-threshold region where significant Mode II loading was present. The influence of various imposed anodic and cathodic potentials was found to be consistent with the surface-roughness-induced crack closure effects. The observed crack growth accelerating effect of high anodic potentials was attributed to the corresponding high removal rate of surface roughness in the wake of the crack, which kept the effective cyclic stress intensity level near the applied values. Crack fractography was studied by scanning electron microscopy. It showed that the fractography generally consisted of three regions; a crystallographic cleavage-like near-threshold region, a feathery and fibrous transition region, and a striated region. Using an etch pitting technique, it was determined that the crack plane and crack propagation directions in the near-threshold region were mainly those of {111} <110>, {110} <112>, {110} <001>, and other higher indexed planes. These crack orientations were effected by the activation of a single slip system or the alternate activation of two intersecting slip systems. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

M.Cur. / Nursing is a stressful activity and therefore it is necessary for nurses to develope effective coping mechanisms, or to strengthen existing ones in a healthy manner, in order to be capable of dealing with stress, arising from their personal and professional lives. It is however, not soley stress itself which predisposes nurses to fatigue (physical, psychological and emotional exhaustion) but rather the chronic nature and excessive amount of stressors which place excessive demands on the energy resources and coping mechanisms of nurses resulting in the ineffective handling of stress which in turn leads to the eventual development of fatigue. The detrimental results of this experience are however not confined to the nurse herself, but extends further to the patient and the organization. Thus, if fatigue is not controlled or dealt with, all parties and organizations concerned could suffer. This research covers the accompaniment function of the psychiatric nurse specialist in the prevention of fatigue in psychiatric nurses by strengthening their mental preparedness. As a possible solution to the experience of fatigue, a structured, accompanied program of three days duration was offered to a group of psychiatric nurses. This group was identified as the experimental group. The control group was only provided with literature giving essential data concerning fatigue. This was done in order to limit the Hawthorne effect of this research. The Solomon four group design was followed in order to eliminate influences on the subjects resulting from the completion of the self-evaluation scale as pre-test. In order to determine the level of fatigue experienced by psychiatric nurses, half/Of / the experimental group were tested before and after the three day structured accompanied program was presented, by means of the self-evaluation scale. The second half of the group were tested once only after the structured accompanied program was held by means of the same scale. The control group was divided and dealt with in the same way except that no structured accompanied program was presented to this group...

Les conditions de fonctionnement rencontrées dans la problématique de nouvelles générations d'alternateurs automobiles avec des chargements variables et un environnement mécanique complexe déformable ont un effet non négligeable sur le comportement mécanique du roulement et par conséquent sur sa durée de vie. Il est proposé dans ce travail une approche permettant de prendre en compte ces paramètres dans l'estimation de la durée de vie des roulements. La répartition des efforts obtenue des considérations statiques sont utilisés dans un modèle dynamique simplifié permettant de déterminer de l'état de contrainte au cours du temps dû au passage de billes sur la piste de roulement. L'approche multi-échelle de Dang Van couplée à une loi de cumul d'endommagement a permis de déterminer le nombre de cycles avant l'apparition des premiers signes de fatigue. La dernière phase du travail concerne l'aspect expérimental qui a montré que le phénomène de fatigue n'est pas la seule cause de dégradation des roulements montés dans les alternateurs automobiles. / The operating conditions encountered in the new generations of automotive alternators with variable loads and a deformable complex mechanical environment have a significant effect on the mechanical behavior of the bearing and hence its fatigue lifetime. An approach that takes into account these parameters in the ball bearing fatigue lifetime has been proposed in this work. The load distribution obtained from static considerations are used in a simplified dynamic model in order to determine the time-dependent stress state due to ball rolling on the raceway. The Dang Van multiscale approach coupled with a damage law was applied to determine the number of cycles before the apparition of the first signs of fatigue. The last phase of work involves the experimental aspect that shows that the fatigue phenomenon is not the only cause of degradation of bearings mounted in automotive alternators.

In this thesis, the fatigue response of arteries to four specific physiological conditions representative of various morphological changes that artery undergo during its lifetime, was explored. Single layered nonlinear elastic micromechanical model of artery was developed for this purpose. A comparative study was completed on fatigue response, in the form of available life and shear stress accumulation, between hypertensive and normotensive arteries. The effects of morphological changes of ageing arteries on the fatigue response of the artery were studied. Change in stiffness, arterial dilation and remodeling were taken into consideration. The effect of undulation of the artery, due to weakening of arterial walls with age or hypertension, on fatigue response, is the third aspect of this study. Lastly, the contribution of the surrounding linear elastic tissue material on fatigue response of the artery was investigated to reflect the in-vivo condition of artery where it is always surrounded by different tissues.

BACKGROUND: Strategic limb occlusion applied after exercise (PEIC) may expedite recovery, not just in directly affected tissue, but over the entire body via circulating factors. METHODS: Twenty active college-age males took part in a single-blind randomized crossover design. Participants underwent intervention and SHAM treatments after strenuous exercise sessions. Peak Torque production and soreness measures were gathered directly before and 24-hours after two exercise sessions. STATISTICAL ANALYSES: A 2 x 2 repeated measures analysis of variance with sidak corrections (significance of p<0.05) was used to analyze peak torque and VAS scores. RESULTS: Significance was not observed between any associated pre- and post-peak torque test (p > 0.05). Post-treatment VAS scores were statistically higher than pre-treatment for all conditions except pre-and post-intervention in the direct leg (P = 0.096). DISCUSSION: The application of PEIC was not associated with any significant differences in peak torque production or soreness measures.

Bibliography: pages 117-120. / A high-speed reciprocating sliding wear test rig was used to examine the metal on metal surface interactions of materials under consideration for application in water powered stoping equipment. The suitability of this test rig was investigated by implementing a test programme covering self-mated stainless steel and stainless steel-on-bronze couples. These couples were examined under water lubricated conditions in a broad test matrix, covering sinusoidal peak velocities of 1, 5 and 10 m/s; loads of 5, 10 and 20N and surface roughness values ranging from 0.2 to 0.4 μm, CLA. Due to poor reproducibility and inconclusive wear behaviours, no inferences could. be made as to the relative performance of the couples tested and no ranking tables could be compiled, In response to these findings, the emphasis changed to the design of a better test facility which could more accurately simulate the tribological interactions of interest. A new laboratory test rig, capable of investigating the performance of material surfaces, rubbing against one another under conditions of high speed reciprocating sliding in specific environments, was designed, built and commissioned. Subsequent tests conducted on this new facility showed average reproducibility for a 122 stainless steel rubbing against a CZ114 manganese bronze to have improved by a factor of two to approximately ± 20%. Initial results confirmed that adhesive wear is the dominant wear mode for the materials under consideration. This is manifested by homogeneous transfer layers and subsequent grooving of these layers.

The reasons for this study are to try to determine what the rest needs of the kindergarten child are and to investigate the effects of different types of rest periods on the behavior of five year olds in a morning kindergarten. It is hoped that the information gained from this study will be of help to kindergarten teachers in determining the type of rest period best suited to the needs of the children that they teach. / Advisor: Sarah Lou Hammond, Professor Directing Paper. / Typescript. / "August, 1954." / "Submitted to the Graduate Council of Florida State University in partial fulfillment of the requirements for the degree of Master of Arts." / Includes bibliographical references (leaves 35-36).

Fatigue gilt als eine der Häufigsten Nebenerscheinungen einer Krebserkrankung und ihrer Therapie. Das Ziel dieser Queschnittsstudie war es die Häufigkeit und das Unterstützungsbedürfnis von Fatigue bei Krebserkrankten während der Strahlentherapie zu untersuchen und mögliche Ansätze eines Unterstützungsangebotes darzustellen. / Fatigue is one of the most common side effects of cancer and its therapy. The aim of this cross-sectional study was to examine the incidence and the need for support of fatigue in cancer patients during radiation therapy and to present possible approaches to support.