The air transport markets affected by global economic climate and regional demand characteristics are evolving fairly dynamically. To cope with the evolving demand and to penetrate desired market segments, operators' usage of aircraft has been getting more and more dynamic with increased deviation from the originally designed mission objectives. The objective of this research is to investigate the effects of in-service rrusslon variation on aircraft structural performance so as to provide airlines with a more realistic approach toward better fleet management. During the research, the scenarios and phenomena causing fleet in-service mission variations were investigated. A survey on the utilisation of world-wide aircraft fleets was conducted and presented. The in-service missions of aircraft fleets were found to vary significantly in terms of mission profile. Furthermore, the utilisation patterns of individual aircraft in the same fleet of a major airline are also being thoroughly analysed. Tremendous variations of mission mixes are found among individual aircraft. In order to analyse the effects of the in-service mission variation, methodologies and models based on fatigue test results have been developed by the author. Actual service data are being input for the effect analysis. It is found that the mission variation has a considerable engineering influence on the aircraft's structural performance either in terms of mission airworthiness or fatigue life span. Finally, a conceptual model, the 'Integrated Airline Fleet Management Model' (IAFM), has been developed as a blueprint for practical application. By implementing the IAFM, airline will be able to obtain a realistic picture of the health of its aircraft. With a more reliable basis for maintenance planning, improved inspection accuracy, reduced maintenance cost and better structural airworthiness can be achieved.

Faculty of Humanities School of Human and Community Development 0206924r nenelunga@hotmail.com / The aim of this study was to contribute to literature the effects of working with traumatized children in a continuous traumatic stress environment more specifically in a township which is historically known as characterised by criminal activities and political oppression, Soweto. The study investigates the levels of compassion fatigue and the sense of coherence of caregivers working in a continuous traumatic stress environment. Working with trauma victims especially children who are perceived as vulnerable and helpless may leave caregivers with feelings of helplessness and hopelessness, anger towards the perpetrators or anger toward the parents for being unable to protect the children. Caregivers may view the environment as unsafe for both their own children and the traumatized children that they treat. These emotions may lead to compassion fatigue, meaning that the caregiver’s relationships at home and work become affected due to trauma work. The caregiver’s ability to manage or cope with a stressful situation may also be affected causing their levels of the sense of coherence to be compromised. This study investigated the levels of compassion fatigue and the sense of coherence among caregivers who work with sexually abused children in Soweto. Compassion fatigue was assessed by using the Compassion Fatigue Scale (CFS) (Figley, 1995, Stamm, 1996). The sense of coherence was measured by the Orientation to Life Questionnaire (OLQ) Antonvosky (1987). The sample group consisted of 25 caregivers working in Soweto. These included nurses, teachers, counsellors and social workers from this area. 2 Results of the study indicated that the majority of the respondents manifested an extremely high risk of compassion fatigue based on the high scores they obtained on the Compassion Fatigue Scale. Interestingly the levels of the sense of coherence for the majority of the participants were also high, which contradicts previous findings. Findings from the qualitative data revealed positive and negative emotions related to the nature of their work. It also became apparent that caregivers with limited resources become frustrated and manifested feelings of inadequacy due to poor referral systems and there was no feedback from other organisation that deal with the children they worked with. Leaving caregivers with feelings of isolation. It also emerged that caregivers used a range of coping strategies in dealing with stressful situations.

No description available.

Orientador: Marcelo dos Santos Pereira / Banca: Mauro Pedro Pers / Banca: Carlos Kiyan / Banca: Rosinei Batista Ribeiro / Banca: Cesar Alves da Silva Leandro / Resumo: Atualmente, as montadoras de automóveis têm procurado reduzir o peso total da estrutura de seus veículos, além das peças e componentes produzidos em aços, por dois motivos principais: um focado nos aspectos de segurança para os passageiros e outro na necessidade em se diminuir as emissões de CO2, melhorando o consumo de combustível. Em linha a estes requisitos buscados, o presente trabalho tem por objetivo caracterizar em fadiga e impacto, uma nova classe de material desenvolvida pelas siderúrgicas, o aço de fases complexas (complex phase steel), de atuação estrutural, utilizado para a confecção da carroceria de veículos. Foram realizados ensaios metalográficos, onde as fases presentes em sua microestrutura foram analisadas e discutidas, e ensaios para avaliar suas propriedades mecânicas em situações de fadiga (ASTM E 466) e impacto (ASTM E 23), seguido de análises fractográficas das superfícies de fratura dos corpos-de-prova utilizados durante estes ensaios, utilizando para isto, um microscópio eletrônico de varredura (MEV). Desta forma, este trabalho mostra que seu potencial de utilização pode ser ampliado, em virtude dos resultados obtidos, que mostraram a homogeneidade de sua microestrutura, com um alto grau de refino, em comparação com outras duas especificações de aços estruturais utilizados convencionalmente pela indústria automotiva, indicando, assim, melhores resultados nos ensaios realizados / Abstract: Currently, automakers have sought to reduce the total weight of the structure of their vehicles, and parts and components produced in steel, for two main reasons: one focused on aspects of safety for passengers and one in the necessity to reduce emissions CO2, improving fuel consumption. In line with these requirements, this study aims to characterize the fatigue and impact, a new class of materials developed, the steel complex phase, with structural actuation, used for making the body of vehicles. To evaluate the characteristics of this specification steel, metallographic tests were conducted, where the phases present in their microstructure was analyzed and discussed, and tests to assess their mechanical properties in situations of fatigue (ASTM E 466) and impact (ASTM E 23) followed by fractográficas analysis of fracture surfaces of the specimens used during these tests, with a SEM. This will show that their potential use could be extended, because the results obtained during tests, which the material was compared with two other specifications of conventional structural steels used in the automotive industry / Doutor

Cette thèse traite d’une approche pragmatique de l'endommagement par fatigue des structures sous un chargement cyclique. Un modèle anisotrope de dommage par fatigue a été développé. L'évolution de la dégradation des propriétés du matériau dépend d’un critère de fatigue (choisi) et de ses gradients. La dégradation du matériau anisotrope guidera la propagation des dommages. La propagation des dommages dépend principalement des crêtes de la «surface» du critère (gradients zéro). L'approche proposée décrit l'amorçage, la propagation des dommages et la rupture structurale sous un chargement multiaxial en fatigue. Pour chaque élément fini, des distributions anisotropes non homogènes des propriétés du matériau sont associées. Schématiquement, il apparaît comme un «surfer» matériel sur la «surface» du critère et les dommages suivent la crête de la «surface» du critère (niveau et gradient). Un critère d'approche globale, basé sur des invariants du tenseur des contraintes, est adopté. La réduction des propriétés des matériaux est affectée à un certain nombre de cycles et à un niveau global de contraintes, en utilisant une courbe de Wöhler expérimentale. Deux formes simplifiées du modèle sont proposées et les résultats sont comparés avec un exemple de référence expérimental (plaque cruciforme) et un cas industriel (pale d’une éolienne d’EDF). Une cartographie avec le critère de Dang Van est également calculée pour analyser les résultats numériques. / A new practical engineering methodology for the analysis of structures under cyclic loading is proposed in this work . A new anisotropic fatigue damage model is developed. The evolution of material properties degradation depends on a failure criterion and its gradient. The anisotropic material degradation will guide the damage propagation. The propagation of damage is mainly depending on the ridges of the criterion’s « surface » (zero gradients). The proposed approach can describe the initiation and propagation of the damage until the structural failure under fatigue loading. For each finite element, non-homogeneous anisotropic distributions of material properties are associated. Schematically, it seems like a material « surfing » on the criterion’s « surface » and damages follow the crest of the criterion’s « surface » (level and gradient). A global approach criterion, based on invariants of the stress tensor, is adopted. The reduction of material properties is assigned to a number of cycles and a global level of stresses, using an experimental Wöhler curve. Two simplified forms of the model are proposed and results are compared with a cruciform experimental reference example and an industrial case. A mapping with Dang Van criterion is also computed to analyze the numerical results.

The majority of gymnasts are young girls. Training hours required to meet competition demands are high and gymnasts begin serious training at a young age. Concerns regarding injury risk are substantial and may be the result of repeated high impact loads experienced during landings from dismounts, tumbling and vaulting. There is currently little information available to coaches regarding the quantity of training that is safe or not safe. The use of acceleration was tested for its efficacy for use in the field to examine risk factors for injury. Risk factors examined were loading and fatigue. Kinematics, ground reaction forces and acceleration were measured during landing from gymnastics skills and also pre- and post fatigue during landing from a vertical jump and a 35cm drop in the laboratory. A pilot study was performed in the field to examine accelerations during gymnastics skills pre- and post-training. Lower body kinematics of landing were notably different between gymnastics skills analysed. Joint positions at touchdown and range of motion available during landing due to these joint positions affect the ability to contribute to energy absorption. Peak ground reaction forces and peak accelerations measured at the pelvis showed significant differences between skills landing on both the hands and the feet. The peak acceleration during landing from gymnastics skills was positively correlated with the peak ground reaction force. A large variability stiffness during landing meant that an estimation of ground reaction force using simple modelling was not successful in improving the correlation. After a fatiguing jumping and landing task peak accelerations measured at the pelvis during landing were increased indicating the use of acceleration for identifying fatigue. Pilot field testing of acceleration during landing from gymnastics skills showed similar results to laboratory results. Pre- and post-training measurements showed no difference in peak accelerations during landing from the skills analysed. The training session completed was not demanding enough to induce enough fatigue to be seen in acceleration values Acceleration has potential to be used to quantify repeated loading and accumulative effects in gymnastics, as well as the presence of fatigue in gymnasts during training sessions.

Typescript. Bibliography: leaves 318-338.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

<p>Fibromyalgi (FM) är ett tillstånd av kronisk smärta, förutom smärtan karaktäriseras sjukdomen även av sömnstörningar, extrem trötthet och kognitiva störningar. Att ständigt leva med smärta innebär en stor stressfaktor och både fysiska, psykiska och stressrelaterade symtom är vanliga. Den ständigt närvarande upplevelsen av fatigue liknar den som beskrivs vid kroniskt trötthetssyndrom. Fatigue definieras som ett tillstånd av onaturlig och onormal eller extrem trötthet i hela kroppen, som inte är relaterat till aktivitet eller ansträngning. Syftet med studien var att beskriva vilka icke-farmakologiska interventioner som förekommer för att lindra fatigue hos patienter med FM. Metoden som användes var en litteraturstudie. Tolv vetenskapliga artiklar granskades och sammanställdes. Resultatet visade att interventioner som kombinerade träning och kognitiv inriktning hade bäst effekt för att lindra fatigue under en längre tid. Vikten av tro på patientens upplevelse av både smärta och fatigue visades sig vara betydelsefullt för att komma vidare i livet. Att stödja patienten med kunskap och engagemang från flera yrkeskategorier belystes som viktiga delar i vården av patienter med FM. Vidare forskning kring teambaserad vård behövs för att tydliggöra resultatet ytterligare.</p>

Objectives: To evaluate the effect of leg muscle fatigue on balance and to determine the contributions of the somatosensory, visual, and vestibular systems to balance of apparently healthy males and females. Design: Forty-two subjects were randomly assigned to either the experimental or control groups and then subdivided based on gender resulting in four groups (10 men/women in the experimental groups and 11 men/women in the control groups). Each subject was pre-tested on the Sensory Organization Test assessment of balance. Subjects in the experimental group then underwent a Wingate Anaerobic Test to induce leg fatigue. Following the Wingate Test subjects were post-tested on the Sensory Organization Test. Subjects in the control group rested quietly for a period of seven minutes prior to post-testing. Subjects: Forty-two volunteers without recent or chronic history of lower extremity injury, neurological deficits, or balance problems participated. Main outcome measures: Ratios for the use of the somatosensory, visual, and vestibular systems and the Composite Score were calculated. A [2(Group) x 2(Gender) x 2(Test)] mixed design ANOVA was used to analyze each of the dependent variables. Results: Analysis of Composite Score demonstrated a significant Group x Test interaction (p<0.010). The breakdown of the interaction showed no significant Test effect (p-value 0.341) for the experimental group. However, there was a significant Test effect (p-value<0.010) for the control group. There were no significant effects of fatigue on somatosensory system ratio. The analysis of the visual system ratio revealed a significant main effect (p-value 0.022) for Group. Analysis of vestibular system ratio revealed a significant main effect for Test (p<0.010). Conclusions: As demonstrated by the results of the present experiment, leg muscular fatigue is associated with significantly decreased balance. In addition, fatigue does appear to have an effect on the utilization of visual and vestibular systems. / Graduation date: 2003