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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.
391

Hidden Failure in Protective Relays: Supervision and Control

Hunt, Richard K. 03 April 1998 (has links)
This thesis performs simulations of a relay supervisory system (RSS) that works passively in conjunction with the existing protective relaying system at a substation. During normal system operating conditions, the RSS supervises the relay system to prevent trips due to hidden failures. During wide area network disturbances, it adapts the relay system to increase security of the power system. The RSS works passively in the sense that it waits for events to occur in the existing relay system before taking any action. The simulation performed includes a model of the RSS, along with simplified models of existing relays, performed in Matlab. A power system model in EMTP provides inputs to the RSS model. Multiple faults are applied to the EMTP model, and the RSS is tested under each fault condition, and with a variety of relay hidden failures. For all tests performed, the simulation of the RSS successfully prevents relay hidden failure from removing circuit elements inadvertently, while allowing correct relay operations to remove circuit elements. / Master of Science
392

Social protection arrangements for retired mineworkers with physical disabilities in Maseru urban, Lesotho.

Tlhaole, Thuso 30 May 2011 (has links)
Social protection is a means of reducing vulnerability on individuals by protecting them against low or declining living standards. This study examines social protection arrangements for mineworkers who retired from the South African mines on account of disabling mine injuries. Over the years, the mining industry has been the source of employment for Lesotho men. Some of the workers have been exposed to occupational injuries that led to their disability and forced retirement. They are thus forced to return to Lesotho where they become dependent on the compensation that they receive from South Africa through Compensation for Occupational Injuries and Diseases Act. The study sought to determine the adequacy of compensation paid to Basotho mineworkers who retired because of disabling mine injuries in Maseru urban. It also investigated existence of complementary social support systems. A qualitative design was utilised in this study as the intention was to obtain in-depth information from the research participants concerning existing social protection arrangements. Semi-structured interview schedule were conducted with both mine workers who retired on account of disabling mine injuries and key informants. The research sample consisted of 47 mine workers who retired on account of disabling mine injuries and 4 key informants that were drawn from the Department of Social Welfare, Ministry of Labour, TEBA (The Employment Bureau of Africa) and National Union of Mine workers. The findings reveal that retired mine workers use most of their compensation income on household expenditures such as food, electricity and fuel. The compensation income ranges from M400 to M5, 000 per month. For the research participants who are at the lower range, the compensation is not adequate because they are below the poverty line. The findings established that the waiting period for compensation was long because only three research participants received their compensation after a waiting period of up to 5 months while the majority waited for more than 5 months. The findings also indicate that the payment of monthly compensation is consistent and paid timely. The results revealed that retired mine workers rely on alternative coping strategies like income generating projects and informal support from relatives and friends. The findings also reveal that the disability status makes it difficult for the beneficiaries to engage in income generating activities thereby exposing them to poverty and income insecurity. The study recommends that government support should be extended to retired mine workers with low compensation income. The study also suggests the introduction of reintegration programmes that would improve the quality of life for retired mineworkers with physical disabilities.
393

La protection sanitaire et sociale au Liban (1860-1963) / Health and social protection in Lebanon (1860-1963)

Yehya, Houssam 26 May 2015 (has links)
Cette thèse cherche à proposer une lecture historicisée, pour le Liban, de la mise en place et l’évolution de la protection sanitaire et sociale en se concentrant sur le rôle et les relations de fait et de droit entre les deux secteurs : public et privé, et l'influence étrangère notamment celle de l’OIT sur la production de la norme libanaise, pendant les trois périodes majeures de l’histoire au Liban : Ottomane, Française et Le Liban indépendant. / This thesis seeks to provide a historicized approach for the Lebanese establishment and development of health and social care by focusing on the role and relationships factual and legal between the two sectors: public and private and the foreign influences including that of the ILO on the production of the Lebanese standard, during the three major periods of history in Lebanon: Ottoman, French and independent Lebanon.
394

A case study of Pennsylvania's antidegradation program the Special Protection Waters Program /

Martin, Danielle L. January 1996 (has links)
Thesis (M.P.A.)--Kutztown University of Pennsylvania, 1996. / Source: Masters Abstracts International, Volume: 45-06, page: 2950. Typescript. Includes bibliographical references (leaf 64).
395

The role of churches as social protection actors: The case of Rwandan refugee migrants in Cape Town

Mukafuku, Clementine January 2021 (has links)
Magister Artium (Development Studies) - MA(DVS) / Migrants and refugees are mostly excluded from the public sector, marginalised from economic activities and threatened by recurrent risks, including unemployment and lack of income. These problems cause vulnerability to economic shocks and deepening poverty. Churches and religious organisations assist migrants through activities that enhance social protection by means of informal coping mechanisms. The study examined factors that contribute towards informal social protection through church activities that facilitate Rwandan refugees and asylum seekers’ lives in Cape Town, South Africa. The literature reviewed in this study reveals that church initiatives and activities contributed significantly towards the reduction of challenges faced by refugees and asylum-seekers.
396

Utrustning för testning mot vatten/damm : Framtagning av utrustning för IP testning av elkapsling.

Dadell, Hampus January 2022 (has links)
Vid tillverkning av skåp för elkapsling har skydd mot vatten och damm stor betydelse. Tillgång till testutrustning som prövar skydd mot vatten och damm ger, effektivitet, kvalité och kostnadsbesparingar vid framtagning av elkapsling. Med högre prestation från företag kan större framsteg tas, där vinning finns gällande utveckling och miljöbesparing. Detta projekt har initierats då företaget Elkapsling AB insett behovet av egen testutrustning gällande vatten och dammskydd. Syftet var att uppnå besparing av tid och kostnader gällande testning av egen produkt. Projektet är genomfört som ett examensarbete för Maskiningenjörutbildningen (TMPRG) på Mittuniversitet (Mid Sweden University) i Östersund. Målet var att framta underlag av konstruktion för utrustning åt Elkapsling AB som uppfyller de krav och önskemål de har givit. Utrustningen var framtagen med hjälp av produktutvecklingsmetodik i projektfaser där framstegen från milstolparna redovisades i form av avstämning med Elkapsling AB spontant efter behov under projektets gång. Projektets resultat kommer i form av konstruktionsunderlag av en dammkammare för testning av dammskydd, verktyg för testning av vattenskydd samt förslag på lösningar av återanvändning av vatten. Detta skapar förutsättningar av effektivitet långsiktig besparing av pengar. Detta kan bidra även till effektivare framtagning av förbättrade produkter från Elkapsling AB. Innan utrustning kan konstrueras krävs tester och mer standardiseringar av komponenter och andra anpassningar efter Elkapsling AB egna behov. Den ekonomiska uppskattningen borde utvecklas till en mer omfattande kalkyl för att ge en bättre uppskattning över projektet riktiga kostnad i helhet / Protection against water and dust is very important in the manufacture of enclosures for electrical enclosures. Access to testing equipment that tests for water and dust protection provides efficiency, quality and cost savings in the production of electrical enclosures. With higher performance from companies, greater progress can be made, with benefits in terms of development and environmental savings. This project has been initiated when the company Elkapsling AB realised the need for its own testing equipment regarding water and dust protection. The aim was to save time and costs for testing of own products. The project is carried out as a degree project for the Mechanical Engineering Program (TMPRG) at Mid Sweden University in Östersund. The goal was to produce a design for equipment for Elkapsling AB that meets the requirements and wishes they have given. The equipment was developed using product development methodology in project phases where progress from milestones was reported in the form of reconciliation with Elkapsling AB spontaneously as needed during the course of the project. The results of the project come in the form of design documentation of a dust chamber for testing dust protection, tools for testing water protection and proposed solutions of water reuse. This creates conditions of efficiency and long-term saving of money. This can also contribute to more efficient production of improved products from Elkapsling AB. Before equipment can be realized, tests and more standardization of components and other adaptations to Elkapsling AB's own needs are required. The financial estimate should be developed into a more comprehensive calculation to give a better estimate of the true cost of the project as a whole. / <p>2022-07-01</p>
397

Model-based design of a protection scheme for shipboard power systems

Zhang, Yujie 13 December 2008 (has links)
A shipboard power system (SPS) should be stable and reliable in order to ensure that the ship has better fight-through capability and increased fault invulnerability. The protection system is designed to minimize the effects of faults in the SPS, which presents challenges, such as increased fault vulnerability and lack of an electrical ground in the system. If protection devices are not updated after power system reconfiguration, they may not protect the power system appropriately. Therefore the development of elaborate digital protection devices for the SPS is required. This thesis focuses on the model-based methodology for designing a protection scheme for SPS based on instantaneous overcurrent digital relays. To achieve this, an instantaneous overcurrent relay model is first developed in MATLAB/Simulink. Then, the Simulink model is downloaded to the DSP-based platform dSPACE, which runs the Simulink model in real-time, to perform hardware-in-the-loop testing (HIL). Thus, through the dSPACE hardware, the proposed relay model is tested for various fault conditions in three HIL platforms. Different electromagnetic transient real-time digital simulators are used to simulate the SPS, to which protection is provided through the relay modeled in dSPACE. Simulation results from these three HIL platforms demonstrate that the proposed overcurrent relay model was successfully modeled, simulated and tested using various tools for model-based design. Testing results show that the developed model can work with different real-time platforms, and that in contrast to a commercial relay, the developed relay model has increased flexibility because settings such as reclose delay and pickup value can be changed online. This feature can be used to develop an advanced relay model with a dynamic pickup value. An advanced relay model will be useful for the SPS, because such system is subject to topological changes and reconfiguration that are not as prevalent in other types of power systems.
398

Hidden Failures in Protection Systems and its Impact on Power System Wide-area Disturbances

Elizondo de la Garza, David C. 27 April 2000 (has links)
This document explores Hidden Failures in protection systems, which have been identified as key contributors in the degradation of Power System wide-area disturbances. The Hidden Failure Modes in which the protection systems may fail to operate correctly and their consequences are identified in a theoretical approach. This theoretical side has its practical counterpart since a number of Hidden Failure Modes are found in real wide-area disturbances. The original definition of Hidden Failure, which is a failure that remains undetected and is uncovered by another system event, is included as well as developments on Hidden Failure sequence of events and a methodology for Hidden Failure identification. This method is based on Protection Element Functionality Defects (PEFD), which are applicable to all the elements included in the protective chain. PEFD are classified in two main groups. Primary and Back-up protection schemes applied for Generators, Buses, Transformers and Transmission Lines are analyzed. The abnormal Power System conditions that each Power System element may have are enumerated. A catalogue of the relays or relay systems, in charge of detecting and stopping the continuous presence of the abnormal conditions is developed. Relay families organize this catalogue. The relaying schemes for five Special Protection Systems are described. Thirty-three Hidden Failures Modes are included based on the relaying implementation for Primary protection, Back-up protection and Special Protection Systems. These Hidden Failures Modes are based on PEFD-A. Hidden Failures related to PEFD-B are included in a general fashion. Wide-area disturbances based on NERC reports are analyzed and Hidden Failures are identified employing the developed methodology. The mechanisms in the disturbances are summarized and are applicable to Primary protection, Back-up protection and Special Protection Systems. Regions of Vulnerability and Areas of Consequence definitions are included and are identified for a Power System wide-area disturbance. For some protection schemes the term Condition of Vulnerability was developed. Regions of Vulnerability and Areas of Consequence will bring the initial steps towards the problem solution. Further research directions are oriented towards the development of a computer-based tool to track the regions of vulnerability in real time. / Master of Science
399

Valoriser les connaissances issues des expériences vécues pour recommander des actions de protection des sources d'eau potable : application du raisonnement à base de cas

Cerutti, Jérôme 19 November 2023 (has links)
Depuis des décennies, les pays du monde entier s'affairent à préserver leurs précieuses ressources en eau potable. Ils cherchent à anticiper les risques et à réduire les impacts anthropiques qui pourraient altérer les sources d'approvisionnement. Au Canada, la protection des sources d'eau potable (PSEP) est mise en œuvre au sein de l'approche à barrières multiples, dont elle est l'une des barrières fondamentales. Cette approche permet une gestion multidimensionnelle de l'eau à l'aide d'outils et des pratiques visant à assurer la qualité de l'eau de la source au robinet. Bien que différents cadres existent pour prendre en compte l'eau dans l'aménagement du territoire, la mise en œuvre de la protection des sources peine à se concrétiser. Pourtant, les acteurs de l'eau et de l'aménagement du territoire ont une grande expérience dans la mise en œuvre d'actions. Alors, comment partager ces expériences afin de les soutenir dans l'identification et la mise en œuvre de futures actions de protection des sources ? Le but de cette thèse est de développer un prototype de système d'aide à la décision à base de connaissances (KB-DSS). Celui-ci a pour objectif de faciliter l'identification d'actions ciblées de PSEP selon les problèmes rencontrés. Pour ce faire, ce prototype a été développé sur la base des connaissances issues des expériences vécues depuis deux décennies au Québec, mettant à contribution des expériences réelles de mise en œuvre d'actions liées à la protection de l'eau. Il est conçu pour être utilisable par tout acteur ayant un intérêt à agir pour protéger les sources d'eau potable à l'échelle locale et régionale, via un transfert de connaissances dans le processus d'élaboration et de mise en œuvre d'actions. En étant un support dans la définition des actions futures, le prototype développé entend encourager les parties prenantes à apprendre les unes des autres. L'originalité de la thèse repose sur l'adoption combinée de l'approche en science du design/de la conception (DSR), qui a servi de lignes directrices pour adopter une démarche collaborative et transparente. Celle-ci a permis une application réussie du raisonnement à base de cas (CBR) au complexe problème de la PSEP dans un cadre de gestion de l'eau et du territoire. De cette démarche sont nés différents outils méthodologiques, procédures et connaissances permettant de mieux comprendre les problèmes liés à la PSEP, mais également d'illustrer la conception intégrale d'un prototype d'aide à la décision à base de connaissances utilisant le CBR. Tout d'abord, le cadre conceptuel (chapitre 1) explore et tente de comprendre les liens qui existent entre la nature des problèmes à résoudre pour protéger l'eau, l'environnement décisionnel et la prise de décision. Pour ce faire, le cadre adopte une approche systémique et holistique superposant différentes théories et concepts tels que la gouvernance de l'eau, la gestion de l'eau, la prise de décision, la rationalité et la connaissance. Cette compréhension des défis sous-jacents à la mise en œuvre de la PSEP permettait de mieux comprendre la complexité du problème à résoudre et posait les bases à l'élaboration du prototype de système CBR proposé. Dans l'optique de mieux comprendre comment les défis soulevés dans le cadre conceptuel se concrétisent en pratique, le second chapitre présente une enquête en ligne documentant la mise en œuvre de la PSEP au Québec. Celle-ci visait à brosser un portrait-diagnostic permettant de mieux comprendre le processus décisionnel, d'identifier qui sont les intervenants et quelles sont les connaissances produites et mobilisées pour la prise de décision sur la PSEP. Les analyses qualitatives et quantitatives des réponses des 208 intervenants retenus ont permis de constater que la mise en œuvre de la PSEP impliquait une grande diversité d'intervenants, de tâches et de connaissances créées et se caractérisait par un fort dynamisme inter-organisationnel. Cependant, on constatait que son processus décisionnel perdait en inclusivité au fil des étapes de mise en œuvre, que les connaissances étaient parfois redondantes et qu'il existait de nombreux enjeux de transfert de connaissances (accès, quantité ou qualité des connaissances) entre les intervenants. Lors de l'enquête en ligne présentée au second chapitre, il a été demandé à certains acteurs (organismes de bassins versants, villes, municipalités régionales de comté) d'illustrer les problèmes liés à la PSEP rencontrés sur le terrain. En parallèle, 102 intervenants se sont auto-recrutés pour participer au processus de design du système d'aide à la décision. Le troisième chapitre présente la démarche d'acquisition et de structuration des connaissances du dit KB-DSS par une approche CBR. Le chapitre décrit une seconde enquête en ligne ayant permis de définir ce qu'est un cas pour la PSEP, soit une expérience vécue qui consiste en une multitude de problèmes et de solutions mises en œuvre. Puis, il décrit la modélisation d'une taxonomie des connaissances ayant permis d'aboutir à des descriptions structurées des cas. La conception des cas repose sur le savoir-faire et les besoins en connaissances exprimés par les acteurs de l'eau. La base de cas constitue l'épine dorsale du prototype de KB-DSS destiné à guider les décideurs dans l'élaboration de solutions fondées sur des expériences passées. Le quatrième chapitre présente le prototype de KB-DSS/CBR pour la protection des sources d'eau potable. Il retrace comment le CBR a été modélisé, structuré, implanté, testé et validé en collaboration avec les 102 acteurs de la gestion et de la gouvernance de l'eau au Québec. Il décrit l'intégralité du processus manuel d'ingénierie de cas pour concevoir des attributs qualitatifs sur la base de la taxonomie des connaissances. Il présente l'édition des cas, le processus et les métriques permettant de retrouver des cas, l'implantation et un exemple d'utilisation ainsi que la validation du prototype, réalisée par une procédure participative rigoureuse et transparente avec un petit groupe d'acteurs de l'eau du Québec. Ainsi, il fournit des preuves empiriques du potentiel positif d'une approche CBR pour la PSEP sur le territoire, et retrace une démarche qui peut être généralisée à d'autres contextes géographiques et socio-économiques similaires. / Countries worldwide have been working for decades to preserve their precious drinking water resources. They seek to anticipate risks or reduce anthropogenic impacts that could alter the water quality and availability. In Canada, drinking water source protection (DSWP), or source water protection (SWP), is implemented as part of the multi-barrier approach and is one of the fundamental barriers. This approach allows for multidimensional water management using tools and practices to ensure water quality from source to tap. Although various frameworks exist to consider water in spatial planning, the implementation of DWSP is struggling to materialize. However, water and spatial planning actors have significant experience implementing actions. So, how can these experiences be shared to support them in identifying and implementing future DWSP actions? The goal of this thesis is to develop a prototype of a knowledge-based decision support system (KB-DSS). The objective of this prototype is to facilitate the identification of targeted actions for water protection according to the problems encountered. To do so, this prototype was developed based on knowledge gained from past experiences conducted over the last two decades in Quebec, using real experiences in implementing actions related to water protection. It is designed to be used by any actor with an interest in contributing for the protection of drinking water sources at the local and regional levels, through the transfer of knowledge in the process of developing and implementing actions. By being a support in the definition of future actions, the developed prototype intends to encourage the actors to learn from each other. The originality of the thesis lies in the combined adoption of the design science approach (DSR), which served as a guideline to adopt a collaborative and transparent approach. This allowed for a successful application of case-based reasoning (CBR) to the complex problem of DWSP in a water and territory management framework. From this approach, various methodological tools, procedures and knowledge were developed to better understand the DWSP problems, but also to illustrate the complete design of a prototype knowledge-based decision support system using CBR. First, the conceptual framework (chapter 1) explores and attempts to understand the links between the nature of the problems to be solved to protect water, the decision-making environment, and the decision-making process. These issues were explored by adopting a system analysis that allowed for layering concepts such as water governance, water management, decision-making, rationality, and knowledge. This holistic understanding of the underlying challenges of DWSP implementation provided a better understanding of the complexity of the problem at hand and laid the foundation for developing the proposed CBR system. To better understand how the challenges raised in the conceptual framework materialize in practice, the second chapter presents an online survey documenting the implementation of DWSP in Quebec. This survey aimed to provide a diagnostic portrait to understand the decision-making process better and identify the actors and the knowledge produced and mobilized for DWSP decision-making. Qualitative and quantitative analyses of the responses from the 208 selected actors revealed that the implementation of DWSP involved a wide variety of actors, tasks and knowledge created and was characterized by great inter-organizational dynamism. However, it was found that the decision-making process becomes less inclusive as actions are implemented. Also, the knowledge was sometimes redundant, and there were many problems with the knowledge transfer (access, quantity, or knowledge quality) between actors. During the online survey presented in the second chapter, selected actors (watershed organizations, municipalities, counties, etc.) were asked to illustrate DWSP-related problems encountered in the field. In parallel, 102 actors were self-recruited to participate in the design process of the KB-DSS. The third chapter presents the acquisition and structuring of DWSP problem-related knowledge. The chapter describes a second online survey that helped define a DWSP case, i.e., a lived experience consisting of a multitude of problems and solutions implemented at various scales by various actors. It then describes the modelling of a knowledge taxonomy that led to structured case descriptions. The design of the cases is based on the expertise and knowledge needs expressed by the water actors. The case base is the backbone of the KB-DSS prototype to guide decision-makers in developing solutions based on past experiences. The fourth chapter presents the prototype KB-DSS/CBR system for DWSP. It traces how CBR was modelled, structured, implemented, tested and validated in collaboration with 102 water management and governance actors in Quebec. It describes the entire manual case engineering process for the design of qualitative attributes from the knowledge taxonomy. It presents the case base, the case edition, and the case retrieval (process and metrics). This chapter also illustrates the implementation using a real-world experience use case, as well as the validation of the prototype, carried out through a transparent, participatory procedure with a small group of water actors in Quebec. Thus, it provides empirical evidence of the high potential of a CBR approach for DWSP in the spatial planning context and describes an approach that can be generalized to other similar geographical and socio-economic contexts.
400

Návrh systému chránění s použitím elektronických přístrojových transformátorů (senzorů) v rozvodně vysokého napětí / Design of protection system using an sensor technology in MV substation

Strapko, Miroslav January 2012 (has links)
Master's thesis deals with use of electronic instrument transformers (sensors) in the protection system in medium-voltage substation. Substation consists of 2 incoming feeders, 2 outgoing feeders for motors, 2 outgoing feeders for power transformers, measuring, bus coupler and bus riser feeder. Incoming feeders are connected to distribution system E.ON by cable lines which were proposed. Protected machines (power transformers and motors with rated power) are connected to switchgear panels of UniGear ZS1 type by cable lines too. Proposed protection system is based on the short-circuit conditions, standard CSN 33 3051 recommendations as well as theoretical backgrounds acquired from technical papers and other publicated literature according to the bibliography. For selected protection functions are defined their parameters. Control, monitoring and protection functions provides REF 542plus relay. Consequently, secondary tests which are part of the commissioning, are given in the practical part of thesis. Secondary tests were performed by relay test system FREJA 300 by Megger. Results of tests are displayed in tripping characteristics.

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