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Redespacho de reativos como ação corretiva para alívio de sobrecargas em Redes de transmissão /Hoji, Eduardo Shigueo. January 2011 (has links)
Resumo: Com a necessidade de atender com qualidade a crescente demanda por energia eletrica, com poucas interrupcoes e com níıveis de tensao satisfatorios, e tendo em vista as restricoes ambientais existentes, que dificultam a implantacao de novos recursos aos sistemas de transmissao, como linhas, usinas, subestacoes, etc., as empresas de transmissao tem buscado otimizar os recursos existentes, operando os sistemas com menos folga o que, em alguns casos, pode ocasionar pequenas sobrecargas nas linhas. Nas estruturas atuais de operacao, acoes corretivas usualmente aplicadas ao alıvio dos sistemas de transmissao, como alteracoes nos nıveis de geracao e corte de cargas, fazem parte das atribuicoes do operador do sistema e estao fora do escopo de acao das empresas transmissoras que podem, contudo, alterar as condicoes de operacao de seus dispositivos, como transformadores, compensadores, etc. Neste trabalho e apresentada uma proposta para o alıvio de pequenas sobrecargas em redes de transmissao com base no controle do fluxo reativo das linhas. As acoes corretivas sao determinadas com base na linearizacao dos parametros do sistema em torno de seu ponto de operacao inicial, solucionando-se um problema de programacao linear (PL) cuja funcao objetivo a ser minimizada e o produto entre o custo dos servicos de suporte de reativos prestados pelos dispositivos e o desvio do sistema de seu ponto de operacao inicial. Haja vista a grande quantidade de dispositivos instalados no sistema que podem fornecer servicos de suporte de reativos e que problemas relativos a potencia reativa sao solucionados localmente, e possıvel reduzir a quantidade de dispositivos "candidatos" a realizacao das acoes corretivas e, consequentemente, o numero de variaveis e restricoes no PL a ser solucionado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The growing demand for electric power associated with the environmental limitations imposed to the expansion of power systems hamper the installation of new facilities, such as transmission lines, substations and power plants, and leads the transmission companies to optimize the existing resources. In consequence, transmission systems operate closer to their boundaries and small overloads may surge. In the deregulated operating environment, the standard overload relief procedures, based on generation redispatch and load shedding, are in charge of the system operator and cannot be performed by the transmission companies, which can, otherwise, modify the control parameters of the transmission system devices, such as transformers, shunt compensators, etc. An overload relief procedure based on reactive power control applicable to small disturbances is presented in this paper. The corrective actions are determined by linearizing the system parameters around the initial operating point and solving a linear problem (LP), that minimizes the product between the total cost of the reactive power support provided by the devices and the deviation of the system from its initial operating point. Considering that reactive sources are spread over the whole system and the solution for reactive power problems can be found locally, the set of devices to be applied for the corrective actions can be reduced and, consequently, the number of variables and constraints to be added to the LP problem. To accomplish that, linear sensitivity factors which relate the reactive flow variation in the overloaded line to the devices' control parameters are applied and the "n" most effective devices to mitigate the overloads can be determined. In many market structures reactive power support is a mandatory service and, in some cases, it is not remunerated. However, despite the low cost of production of reactive power... (Complete abstract click electronic access below) / Orientador: Antonio Padilha Feltrin / Coorientador: Javier Contreras Sanz / Banca: Percival Bueno Araújo / Banca: Dilson Amancio Alves / Banca: Eduardo Nobuhiro Asada / Banca: Madson Cortes de Almeida / Doutor
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Relationships between Job Variables: The Moderating Effects of Support and the Mediating Effects of Job Satisfaction, Affective Commitment and Continuance Commitment in the Support Worker IndustryBotha, Hanlie January 2007 (has links)
The factors associated with employees' work related attitudes and cognitions were examined. A sample of employees from Community Living Trust (CLT), an organisation within the disability support worker industry, completed a questionnaire that included several measures: supervisor and colleague support, role conflict, role ambiguity and role overload, time-based, strain-based and behaviour-based work-to-family/family-to-work conflict, organisational commitment, job satisfaction and turnover intentions. The purpose of this study was to explore the extent to which supervisor and colleague support contributed to a reduction in role conflict, role ambiguity and role overload. In addition, the relationship between support and work-to-family/family-to-work conflict were also explored. Finally, the organisational outcomes, in particular organisational commitment, job satisfaction and turnover intentions, were examined. It was found that supervisor and colleague support did, in some cases, moderated the relationship between role stressors, conflict and job satisfaction / organisational commitment. It was also found that job satisfaction and affective commitment mediated the relationship between the role stressors, WF strain-based conflict and turnover intentions. The major implications from this research are that human resource initiatives should be developed that aims to identify the support needs employees may have, in order to increase levels of job satisfaction and organisational commitment and decrease levels of turnover intentions. The final chapter of this research explored the practical implications to the organisation, employees and the need for future research.
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Excessive Fluid Overload Among Haemodialysis Patients : Prevalence, Individual Characteristics and Self-regulation of Fluid IntakeLindberg, Magnus January 2010 (has links)
This thesis is comprised of four studies and concerns haemodialysis patients’ confidence in being able to manage fluid intake between treatment sessions, and whether the fluid intake is influenced by certain modifiable characteristics of the persons in question. The overall aim was to study aspects of excessive fluid overload and haemodialysis patients’ self-regulation of fluid allotment from a bio-psychosocial and behavioural medicine perspective. The extent of non-adherence to fluid allotment was described in Study I. National registry data were used. Three out of ten Swedish haemodialysis patients had excessive fluid overload and one out of five was at risk for treatment related complications due to too rapid ultrafiltration rate. The objective in Study II was to develop and psychometrically evaluate a self-administered scale to measure situation-specific self-efficacy to low fluid intake. The measure (the Fluid Intake Appraisal Inventory) was found to be reliable and valid in haemodialysis settings. Subgroups based on individual profiles of self-efficacy, attentional style and depressive symptoms were explored in Study III using a cluster analytic approach. Three distinct subgroups were found and the subgroup structure was validated for clinical relevance. The individuals’ profile concerning self-efficacy, attentional style and depressive symptoms has to be taken into account in nursing interventions designed to reduce haemodialysis patients’ fluid intake. In Study IV, an intervention designed to reduce haemodialysis patients’ fluid intake was introduced and its acceptability, feasibility and efficacy were evaluated and discussed. Acceptability of such an intervention was confirmed. Addressing beliefs, behaviours, emotions and physical feelings is clinically feasible and may reduce haemodialysis patient’s excessive fluid overload. This thesis indicates that there is a potential for improvement in the fluid management care of haemodialysis patients. Behavioural nursing strategies that aim to assist patients to achieve fluid control should be applied more extensively. Cognitive profiles of the patients should be taken into account when targeted nursing intervention aiming to encourage and maintain the patient’s fluid control is introduced.
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Évaluation des désordres cardiovasculaires chez des souris bêta-thalassémiquesStoyanova, Ekatherina 12 1900 (has links)
L’hémoglobine est une protéine contenue dans les globules rouges dont la principale fonction est le transport de l’oxygène. Chaque molécule d’hémoglobine est un tétramère constitué de deux paires de globines identiques de type α et β. La β-thalassémie est une maladie génétique hématopoïétique provenant de mutations du gène encodant l'hémoglobine. Ce désordre se caractérise par une diminution ou une absence totale de la synthèse de la chaîne β-globine résultant principalement en une anémie hémolytique sévère ainsi que des complications multisystémiques, telles que la splénomégalie, des déformations osseuses et une dysfonction hépatique et rénale.
Actuellement, les transfusions sanguines chroniques représentent le traitement standard des patients β-thalassémiques. Cette thérapie nécessite l’administration conjointe d’un traitement chélateur de fer puisqu’elle entraîne une accumulation pathologique du fer, considéré à ce jour comme la source principale des complications cardiovasculaires de la β-thalassémie. Néanmoins, malgré le traitement efficace de la surcharge de fer transfusionnelle, l’insuffisance cardiaque demeure encore la principale cause de mortalité chez les patients atteints de β-thalassémie. Cette observation indique possiblement la présence d’un mécanisme complémentaire dans le développement de la physiopathologie cardiaque β-thalassémique.
L’objectif du présent projet consistait donc à étudier les altérations cardiovasculaires de la β-thalassémie indépendamment de la surcharge de fer transfusionnelle. En utilisant un modèle murin non-transfusé de la β-thalassémie majeure, nous avons d’abord évalué in vivo, par méthode d’imagerie novatrice échographique à haute fréquence, les propriétés hémodynamiques vasculaires. Nos résultats d’index de Pourcelot ainsi que de résistance vasculaire périphérique totale ont démontré une perturbation de l’écoulement microcirculatoire chez les souris β-thalassémiques non-transfusées. Subséquemment, nous avons étudié la fonction endothéliale de régulation du tonus vasculaire de vaisseaux mésentériques isolés. Nos résultats ont révélé un dysfonctionnement de la réponse vasodilatatrice dépendante de l’endothélium chez les souris β-thalassémiques malgré une augmentation de l’expression de l’enzyme de synthèse du monoxyde d’azote ainsi qu’un remodelage de la carotide commune caractérisé par un épaississement de la paroi vasculaire. Finalement, notre étude échocardiographique de la fonction et la morphologie cardiaque a montré, chez les souris β-thalassémiques, le développement d’une hypertrophie et une dysfonction ventriculaire gauche en l’absence de transfusions sanguines chroniques ou de dépôts directs de fer dans le myocarde.
L’ensemble des résultats présentés dans le cadre de cette thèse indique la présence d’une pathologie cardiovasculaire chez les souris β-thalassémiques non-transfusés. Nos travaux permettent de proposer un mécanisme de la pathophysiologie cardiovasculaire β-thalassémique, indépendant de la charge de fer transfusionnelle, impliquant les effets compensatoires d’une anémie chronique combinés à une vasculopathie complexe initiée par les érythrocytes endommagés et l’hémolyse intravasculaire. / Hemoglobin is the major protein in red blood cells and is responsible of the oxygen transport. Each hemoglobin molecule is a tetramer consisting of two identical α- and β-globin subunits. β-thalassemia is a genetic hematopoietic disease caused by mutations in hemoglobin genes. This disorder is characterized by a decrease or absence of production of β-globin chain leading mainly to a severe hemolytic anemia and several systemic manifestations, including splenomegaly, skeletal deformities as well as hepatic and renal dysfunctions.
Chronic blood transfusions remain the standard treatment for β-thalassemic patients. This therapy requires iron chelating management since it leads to pathological iron accumulation which is currently considered the main cause of cardiovascular complications of β-thalassemia. However, despite adequate control of transfusional iron loading, heart failure remains the leading cause of mortality in β-thalassemia. This issue is possibly indicative of additional pathogenic mechanisms underlying the development of the β-thalassemic cardiac pathology.
The objective of the present research project was to study cardiovascular alterations of β-thalassemia independently of transfusional iron overloading. Using an untransfused murine model of β-thalassemia major, we have evaluated in vivo, by non-invasive high-frequency ultrasound imaging, vascular hemodynamic properties. Our results of Pourcelot indices and total peripheral vascular resistance have shown microcirculatory flow disturbances in untransfused β-thalassemic mice. Consequently, we have studied ex vivo the endothelial vasomotor function in isolated mesenteric arterioles. Our findings have pointed out endothelium-dependent vasodilator dysfunction in β-thalassemic mice despite increased expression of nitric oxide synthase, as well as remodeling of the common carotid artery wall. Lastly, our echocardiography studies of heart morphology and function in β-thalassemic mice have demonstrated the development of left ventricle hypertrophy and dysfunction in the absence of chronic blood transfusions or direct myocardial iron deposits.
In conclusion, findings presented in this thesis have demonstrated for the first time development of severe cardiovascular complications in untransfused β-thalassemic mice. Based on our results, we have proposed a novel mechanism, independent of direct myocardial iron deposition, responsible for the cardiovascular complications in β-thalassemia. This model combines compensatory effects of chronic anemia with a complex vasculopathy initiated by abnormal erythrocytes and intravascular hemolysis.
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The Role of Hepcidin in Regulation of Iron Balance in BatsStasiak, Iga 17 September 2012 (has links)
Iron storage disease is a significant cause of liver disease and mortality in captive Egyptian fruit bats (Rousettus aegyptiacus). The nature of the susceptibility in this and other captive exotic species to iron storage disease is not clear. Hepcidin, a key iron regulatory hormone, is involved in the regulation of iron absorption in humans and other mammalian species and a deficiency in hepcidin has been associated with a number of genetic mutations resulting in hemochromatosis in humans. The objectives of this thesis were to identify whether there is a functional mutation in the hepcidin gene in the Egyptian fruit bat that may increase the susceptibility of this species to iron storage disease, and whether there is a functional deficiency in hepcidin gene expression in the Egyptian fruit bat in response to iron challenge. We compared the coding region of the hepcidin gene amongst several species of bats and investigated hepcidin response to intramuscular injection of iron dextran amongst three species of bats with variable susceptibility to iron storage disease; the Egyptian fruit bat, the straw-colored fruit bat (Eidolon helvum), and the common vampire bat (Desmodus rotundus). While a number of genetic differences were identified amongst species, a functional mutation that could result in decreased hepcidin activity was not identified in the Egyptian fruit bat. Bats exhibited marked variation in hepcidin gene expression, with the highest level of hepcidin response to iron challenge in the common vampire bat. While the Egyptian fruit bat exhibited significant hepcidin response to iron challenge, the magnitude of response was lower than that in the common vampire bat and lower than expected based on findings in healthy humans. The straw-colored fruit bat did not exhibit any hepcidin response despite a significant increase in iron stores, which suggests this species may have evolved an alternate mechanism for coping with excessive iron or may be more susceptible to iron overload than previously recognized. / Toronto Zoo Scholarship Fund
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Excessive Fluid Overload Among Haemodialysis Patients : Prevalence, Individual Characteristics and Self-regulation of Fluid IntakeLindberg, Magnus January 2010 (has links)
This thesis is comprised of four studies and concerns haemodialysis patients’ confidence in being able to manage fluid intake between treatment sessions, and whether the fluid intake is influenced by certain modifiable characteristics of the persons in question. The overall aim was to study aspects of excessive fluid overload and haemodialysis patients’ self-regulation of fluid allotment from a bio-psychosocial and behavioural medicine perspective. The extent of non-adherence to fluid allotment was described in Study I. National registry data were used. Three out of ten Swedish haemodialysis patients had excessive fluid overload and one out of five was at risk for treatment related complications due to too rapid ultrafiltration rate. The objective in Study II was to develop and psychometrically evaluate a self-administered scale to measure situation-specific self-efficacy to low fluid intake. The measure (the Fluid Intake Appraisal Inventory) was found to be reliable and valid in haemodialysis settings. Subgroups based on individual profiles of self-efficacy, attentional style and depressive symptoms were explored in Study III using a cluster analytic approach. Three distinct subgroups were found and the subgroup structure was validated for clinical relevance. The individuals’ profile concerning self-efficacy, attentional style and depressive symptoms has to be taken into account in nursing interventions designed to reduce haemodialysis patients’ fluid intake. In Study IV, an intervention designed to reduce haemodialysis patients’ fluid intake was introduced and its acceptability, feasibility and efficacy were evaluated and discussed. Acceptability of such an intervention was confirmed. Addressing beliefs, behaviours, emotions and physical feelings is clinically feasible and may reduce haemodialysis patient’s excessive fluid overload. This thesis indicates that there is a potential for improvement in the fluid management care of haemodialysis patients. Behavioural nursing strategies that aim to assist patients to achieve fluid control should be applied more extensively. Cognitive profiles of the patients should be taken into account when targeted nursing intervention aiming to encourage and maintain the patient’s fluid control is introduced.
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The influence of work stress and work support on burnout in public hosptial nurses.Spooner-Lane, Rebecca January 2004 (has links)
Lazarus and Folkman's (1984) transactional stress-strain-coping theory provides the theoretical background for the present thesis. This theory proposes that strain (i.e., burnout) occurs when demands (i.e., work stressors) exceed coping resources (e.g., social support). The current thesis explores the influence of social support on the stress-burnout relationship in nurses. A sample of Australian nurses working across three public hospitals in Brisbane's metropolitan district were recruited to investigate the nature and level of burnout experienced by nurses. Burnout is characterised by emotional exhaustion, depersonalisation and reduced personal accomplishment. The present research addresses gaps in the empirical literature by investigating the key work stressors experienced by Australian nurses and by establishing nurses' referent levels of work stress, social support, and burnout. In addition, the research explores the complex relationships between work stress, social support and burnout. The majority of nursing studies have failed to consider how support from within the nurses' work environment mitigates burnout. The present research builds upon previous nursing literature by examining the "main&qout; and "buffering" effect hypotheses. Studies have consistently found support for the main effect model, however the hypothesis that social support buffers the negative effects of stress has resulted in highly conflicting findings. Some theorists (Cohen & Wills, 1985; Cutrona & Russell, 1990) propose that the buffering effects of social support will only be found if there is an adequate match between the needs elicited by the stressful event and the type of support an individual receives. The present study extends the stress or support matching theory by exploring the matching between specific types of stressors to specific types (i.e., emotional and instrumental) and sources (i.e.,supervisor and coworkers) of support. Cutrona (1990) suggests that the controllability of a stressor is the primary dimension in determining an appropriate match between stressors and types of support. Cutrona proposes that controllable stressful events elicit needs for instrumental support and uncontrollable events elicit needs for emotional support. Heeding Cutrona's advice, independent raters classified nurses' work stressors as controllable or uncontrollable stressful events prior to investigating the stressor-support matching theory. Three sequential studies were undertaken to explore the variables of interest to this research program. In Study 1, focus groups were conducted with 68 nurses (11 males, 34 females) from two public hospitals. The qualitative data was subjected to content analysis. The findings revealed that Australian nurses are exposed to a range of job-specific stressors (i.e., Job Conditions, Job Uncertainty, Interpersonal Conflict and a Lack of Professional Recognition and Support) and generic role stressors (i.e., Role Overload, Role Conflict and Role Ambiguity). The findings prompted the research to utilise Wolfgang's (1988) Health Professions Stress Inventory to measure nurses' job-specific stressors and Osipow and Spokane's (1987) Occupational Roles Questionnaire to measure nurses' role stressors in Study 2. The findings from Study 1 also confirmed that the way nurses perceive work support is consistent with current social support literature. Nurses indicated that their two main sources of support were their coworkers and their supervisor. Furthermore, nurses discussed social support from a multidimensional perspective, recognising different types of support that were broadly classified as emotional and instrumental support. Based on these findings, the researcher developed a work support measure specifically for the purpose of this research. Items were taken from established social support scales and were slightly modified to ensure that they were contextually relevant to nurses. In Study 2, 273 nurses (38 males, 235 females) completed a multi-measure questionnaire. While there was sufficient research evidence to indicate that the Occupational Roles Questionnaire (Osipow & Spokane, 1987) and the Maslach Burnout Inventory (Maslach, Jackson, & Leiter, 1996) possess adequate levels of reliability and validity, less was known about Wolfgang's Health Professions Stress Inventory and the work support scales designed for this research program. Factor analysis of the Health Professions Stress Inventory revealed a four-factor solution: Lack of Professional Recognition and Support, Patient Care Uncertainty, Job Conditions, and Interpersonal Conflict. Cronbach's coefficient alphas ranged from .62 to .83. Factor analysis of the Coworker Support Scale revealed a two-factor solution, representing emotional and instrumental support. Cronbach's coefficient alphas for the Emotional Coworker Support and Instrumental Coworker Support were .92 and .88 respectively. Contrary to expectations, factor analysis of the Supervisor Support Scale revealed a one-factor solution. It was therefore deemed appropriate to examine Supervisor Support as a unidimensional construct in subsequent analyses. Cronbach's coefficient alpha for the Supervisor Support scale was .96. Overall, the results from Study 2 provided supporting evidence to suggest that the measures used in the current research program were psychometrically sound. In Study 3, the data collected in Study 2 was subjected to further statistical analysis. The findings from Study 3 indicated that overall, the sample of Australian nurses reported low to moderate levels of work stress, moderate levels of work support and moderately high levels of burnout. For Emotional Exhaustion, predictor variables accounted for 42.2% of the total variance. Sociodemographic factors explained a small but significant proportion of the variance (2.7%). Work stressors however, were the main predictors of Emotional Exhaustion, explaining 41.5% of the total variance. Role Overload, Job Conditions and Role Conflict were the main determinants of Emotional Exhaustion, with Role Overload explaining most of the variance. For Depersonalisation, the predictor variables accounted for 34.2% of the total variance. Sociodemographic factors (11.5%) and work stressors (33.6%) both explained a significant proportion of the variance. Role Conflict and Patient Care Uncertainty were the main determinants of Depersonalisation, with Role Conflict explaining most of the variance. For Personal Accomplishment, Role Conflict and Role Ambiguity explained 20.5% of the total variance, with Role Conflict explaining most of the variance. Sociodemographic factors and job-specific stressors were not significant Predictors of Personal Accomplishment. Evidence for main effects of work support on burnout were limited. There was no evidence to suggest that work support had significant main effects on Emotional Exhaustion. Supervisor Support had a small, but significant main effect on Depersonalisation (â = -.15, p < .05) and Personal Accomplishment (â = -.24, p < .01). There was no evidence of main effects for Emotional and Instrumental Coworker Support. Furthermore, the present research found no significant evidence to support the buffering effect of work support on burnout. Theoretical and practical implications of these findings are discussed.
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Redespacho de reativos como ação corretiva para alívio de sobrecargas em Redes de transmissãoHoji, Eduardo Shigueo [UNESP] 25 February 2011 (has links) (PDF)
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hoji_es_dr_ilha.pdf: 852924 bytes, checksum: 9b1bcf1d76e563dd1037dc628a5c3e2e (MD5) / Fundação de Ensino Pesquisa e Extensão de Ilha Solteira (FEPISA) / PROPG - Programa de Pós-Graduação / Com a necessidade de atender com qualidade a crescente demanda por energia eletrica, com poucas interrupcoes e com níıveis de tensao satisfatorios, e tendo em vista as restricoes ambientais existentes, que dificultam a implantacao de novos recursos aos sistemas de transmissao, como linhas, usinas, subestacoes, etc., as empresas de transmissao tem buscado otimizar os recursos existentes, operando os sistemas com menos folga o que, em alguns casos, pode ocasionar pequenas sobrecargas nas linhas. Nas estruturas atuais de operacao, acoes corretivas usualmente aplicadas ao alıvio dos sistemas de transmissao, como alteracoes nos nıveis de geracao e corte de cargas, fazem parte das atribuicoes do operador do sistema e estao fora do escopo de acao das empresas transmissoras que podem, contudo, alterar as condicoes de operacao de seus dispositivos, como transformadores, compensadores, etc. Neste trabalho e apresentada uma proposta para o alıvio de pequenas sobrecargas em redes de transmissao com base no controle do fluxo reativo das linhas. As acoes corretivas sao determinadas com base na linearizacao dos parametros do sistema em torno de seu ponto de operacao inicial, solucionando-se um problema de programacao linear (PL) cuja funcao objetivo a ser minimizada e o produto entre o custo dos servicos de suporte de reativos prestados pelos dispositivos e o desvio do sistema de seu ponto de operacao inicial. Haja vista a grande quantidade de dispositivos instalados no sistema que podem fornecer servicos de suporte de reativos e que problemas relativos a potencia reativa sao solucionados localmente, e possıvel reduzir a quantidade de dispositivos “candidatos” a realizacao das acoes corretivas e, consequentemente, o numero de variaveis e restricoes no PL a ser solucionado... / The growing demand for electric power associated with the environmental limitations imposed to the expansion of power systems hamper the installation of new facilities, such as transmission lines, substations and power plants, and leads the transmission companies to optimize the existing resources. In consequence, transmission systems operate closer to their boundaries and small overloads may surge. In the deregulated operating environment, the standard overload relief procedures, based on generation redispatch and load shedding, are in charge of the system operator and cannot be performed by the transmission companies, which can, otherwise, modify the control parameters of the transmission system devices, such as transformers, shunt compensators, etc. An overload relief procedure based on reactive power control applicable to small disturbances is presented in this paper. The corrective actions are determined by linearizing the system parameters around the initial operating point and solving a linear problem (LP), that minimizes the product between the total cost of the reactive power support provided by the devices and the deviation of the system from its initial operating point. Considering that reactive sources are spread over the whole system and the solution for reactive power problems can be found locally, the set of devices to be applied for the corrective actions can be reduced and, consequently, the number of variables and constraints to be added to the LP problem. To accomplish that, linear sensitivity factors which relate the reactive flow variation in the overloaded line to the devices’ control parameters are applied and the “n” most effective devices to mitigate the overloads can be determined. In many market structures reactive power support is a mandatory service and, in some cases, it is not remunerated. However, despite the low cost of production of reactive power... (Complete abstract click electronic access below)
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Séquencement d’une ligne de montage multi-modèles : application à l’industrie du véhicule industriel / Mixed model assembly line sequencing : application in truck industryAroui, Karim 27 May 2015 (has links)
Dans cette thèse, nous considérons le problème du séquencement sur une ligne de montage multi-modèles de véhicules industriels. Pour équilibrer au mieux la charge dynamique des opérateurs, la minimisation de la somme des retards à l’issue de chaque véhicule est proposée.Deux approches peuvent être utilisées pour optimiser le lissage de charge dans un problème de séquencement : l’utilisation directe des temps opératoires ou le respect de règles. La plupart des travaux appliqués à l’industrie automobile utilisent l’approche de respect de règles. Une originalité de ce travail est d’utiliser l’approche de la prise en compte directe des temps opératoires.L’étude de la littérature de ce problème a dévoilé deux lacunes dans les travaux précédents : l’essentiel des travaux modélisent un seul type d’opérateurs d’une part, et proposent des heuristiques ou des métaheuristiques pour résoudre ces problèmes, d’autre part. L’originalité de ce travail est de tester des méthodes exactes pour des instances industrielles et de modéliser le fonctionnement de trois différents types d’opérateurs spécifiques au cas industriel.Deux méthodes exactes sont développées : la programmation linéaire mixte et la programmation dynamique. Une étude expérimentale des facteurs de complexité sur des instances académiques des deux modèles est développée. Les modèles sont aussi testés sur des instances du cas d’étude.Par ailleurs, le problème est traité par deux méthodes approchées : une heuristique basée sur la programmation dynamique d’une part, et des métaheuristiques (algorithme génétique, recuit simulé et un couplage des deux) d’autre part. Les deux approches sont testées sur des instances académiques et des instances du cas d’étude.Ce travail a permis d’apporter une solution intéressante d’un point de vue industriel puisqu’il prend en compte les caractéristiques de la ligne de montage (opérateurs spécifiques) et améliore significativement la qualité du séquencement en un temps de calcul raisonnable. / In this thesis, the problem of sequencing mixed model assembly lines (MMAL) is considered. Our goal is to determine the sequence of products to minimize the work overload. This problem is known as the mixed model assembly line sequencing problem with work overload minimization (MMSP-W). This work is based on an industrial case study of a truck assembly line.Two approaches can be used to minimize the work overload: the use of task operation times or the respect of sequencing rules. Most of the earlier works applied in car industry use the latter approach. The originality of this work is to employ the task operation times for the generation of the product sequence in a MMAL.The literature review has highlighted two main gaps in previous works: most of the papers consider a single type of operators, and propose heuristics or metaheuristics to solve the problem. The originality of this work is to test exact methods for industrial case instances and to model three different types of operators.Two exact methods are developed: the mixed integer linear programming and dynamic programming. The models are tested on industrial case study instances. An experimental study is developed for both approaches in order to understand the complexity factors.Moreover, the problem is treated by two approximate methods: a heuristic based on dynamic programming and metaheuristics (genetic algorithm, simulated annealing and a hybrid method based on both genetic algorithm and simulated annealing). All approaches are tested on academic instances and on real data from the industrial case study.
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ÄR EXCENTRISK TRÄNING EN EFFEKTIV METOD FÖR ATT UTVECKLA HOPPHÖJD, MUSKELSTYRKA ELLER EFFEKTUTVECKLING FÖR TRÄNADE OCH SKADEFRIA INDIVIDER? : En översiktsartikel / IS ECCENTRIC TRAINING AN EFFICIENT METHOD TO ENHANCE JUMP HEIGHT, MUSCLE STRENGTH OR POWER IN TRAINED AND NON-INJURED INDIVIDUALS? : A reviewHedman, Victor January 2018 (has links)
I denna översiktsartikel granskades 17 randomiserade kontroll studier som undersökt hur excentrisk träning har påverkat hopphöjd, muskelstyrka och effektutveckling hos tränade och skadefria individer, med mål att svara på följande två frågeställningar; 1) ”Är excentrisk träning ett effektivt sätt att träna för att utveckla hopphöjd, muskelstyrka och effektutveckling för tränade och skadefria individer?” 2) ”Om det är det, hur bör denna träning i så fall se ut?”. Majoriteten av insamlade studier kunde inte urskilja några signifikanta förändringar till följd av excentrisk träning. Endast sex av 17 studier kunde påvisa akuta såväl som kortsiktiga signifikanta förbättringar av hopphöjd, muskelstyrka och effektutveckling. Dock ifrågasätts relevansen av dessa fynd då effektstorleken inte rapporterats i alla studier samt att utformningen av studierna varierat från en studie till en annan. Sammantaget lyckades inte de granskade studierna bevisa att excentrisk träning är en effektiv metod för att utveckla hopphöjd, muskelstyrka och effektutveckling hos tränade och skadefria individer. / In this review 17 randomized control studies were reviewed that had examined the effects of eccentric training regarding jump height, strength and power for trained and non-injured individuals. The purpose of the review was to answer the following two questions at issue; 1) “Is eccentric training an efficient method to enhance jump height, strength or power for trained and non-injured individuals?” 2) “If so, how should that training regime be designed?”. Most of the included studies could not distinguish any significant changes because of eccentric training. Only six out of 17 studies could show acute as well as short term significant improvements in jump height, strength and power. The relevance of these findings is questioned since effect size has not been reported in all the included studies. The variety between the different interventions in each study also makes it difficult to compare the results between one study and another. In conclusion, the reviewed studies failed to show that eccentric training is an effective method to enhance jump height, strength and power for trained and non-injured individuals.
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