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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.
61

Power plant system reliability analysis : applications to insurance risk selection and pricing

Trayhorn, Benjamin January 2012 (has links)
Within the Speciality Engineering Insurance Field the use of engineering opinion is the main component in risk analysis for underwriting decision making. The use of risk analysis tools to quantify the risk associated with perils such as mechanical breakdown is limited. A reliability model for the risk analysis of mechanical breakdown risk for the power generation sector, PowerRAT, has been developed and its performance evaluated against historic claim data. It has proven to closely forecast actual losses over a portfolio of power plants, and differentiate between power plant type; conventional steam, simple and combined cycle gas turbine plants. Differentiation based on the factors of equipment type and policy terms has been demonstrated. A review of existing survey report methodology has shown highly variable quality of reports with significant missing information on which to make underwriting decisions. A best practice survey report contents has been proposed in order to provide a consistent level of information for comparison with other risks. The development cycle of PowerRAT has led to a proposed framework for the development of future risk assessment tools for insurance. This is built on four main areas: risk identification, data analysis, calculation methodology and insurance factors.
62

Refinery Power Distribution Reliability and Interruption

Nygren, Leif Unknown Date
No description available.
63

Kartläggning av faktorer som kan minska antalet återinkopplingar i elnätet / A survey of factors which can reduce the number of short interruptions in the electrical grid

Mellqvist, Roger January 2015 (has links)
Vattenfall Eldistribution AB distribuerar el till ca 900 000 kunder i Sverige. Det handlar om både privatkunder och företagskunder. Enheten Nätdrift vars driftcentral är placerad i Trollhättan har till uppgift att se till att elnätet är spänningssatt och att man skall minimera avbrottstiderna. Då dagens samhälle är allt mer beroende av störningsfri leverans av el är det viktigt att kartlägga faktorer som orsakar korta avbrott på nätet. Ett kort avbrott definieras som ett avbrott som varar allt från 100 millisekunder till 3 min. I myndigheternas föreskrifter finns inga krav angående hur frekvent korta avbrott får förekomma i elnätet, då dessa avbrott oftast är orsakade av åska och därmed omöjliga att förutse. Genom att åskan åstadkommer en nedbrytning av isolationshållfastheten i systemet kan en ljusbåge uppträda vilken drar med sig nätspänningen till jord. Ledningsskydden känner av förekommande felströmmar och löser ut. En konsekvens av detta är att ett kort avbrott av nätets driftspänning uppstår innan en återinkoppling kan ske och normal drift åter föreligger. Arbetet är avgränsat genom att det endast handlar om avbrott orsakade av åsköverspänningar samt endast spänningsnivåer över 1000V. Utifrån litteraturstudier som är gjorda på kurslitteratur, forskning samt Vattenfalls eget material i ämnet, har arbetet resulterat i ett antal olika återgärder som skulle kunna minska antalet korta avbrott i högspänningsnätet. Detta examensarbete förordar att arbetet med att identifiera och analysera bakomliggande orsaker och möjliga åtgärder för att kunna minska antalet återinkopplingar fortsätter. I en fortsatt fördjupad analys bör även ekonomiska aspekter vägas mot nyttan av åtgärderna för både kunder och nätbolag. / In Sweden Vattenfall Eldistribution AB provides electrical power to approximatly 900000 customers, both private customers and business customers. The grid is operated from Trollhättan and it is the division Nätdrift's main purpose to, beside keeping the grid operating with a minimum of disturbances, to plan, optimize, manage and develop the operating systems. The society today is increasingly depending of an uninterrupted transmission of electricity and therefore it is important to make a survey of the factors that causes short interruptions in the grid. A short interruption is defined as an interruption that has a duration between 100 ms and 3 min. The regulations provided by the authorities do not include any demands regarding how frequent these short interruptions may occure in the grid. This is due to the fact that they are mostly caused by overvoltage from lightning storms, and therefore hard to predict. When lightning strikes on an overhead line, a breakdown of the insulation will occur due to overcurrent and a shortcut will ignite an arc between the wire and earth. This will start the phase-fault protection system to react and activate the feeder circuit breakers involved. This protection of the grid will cause a short interruption of the power supply before the automatic reclosing repowers the overhead line back to normal operating voltage. This thesis has been based on short interruptions caused by lightning and there has been no considerations taken to short interruptions occurring in grids with a voltage level below 1000 V. In this thesis a study of literature has been conducted from course literature, research and Vattenfalls internal documents. The result has been that a number of possible actions can be taken in consideration for making short interruptions less frequent. This thesis is also recommending that the survey of actors which are causing short interruptions continues. When doing so, the economical aspects should also be taken in consideration regarding the customers as well as the network company.
64

Improving the Management of Controllers’ Interruptions through the Working Awareness Interruption Tool: WAIT

Alqahtani, Meshael January 2014 (has links)
Interruptions in time-critical, dynamic, and collaborative environments, such as air traffic control (ATC), can provide valuable, task-relevant information. However, they also negatively impact task performance by distracting the operator from on-going tasks and consuming attention resources. This thesis develops and assesses a tool to assist radar air traffic controllers in managing interruptions. Field observations and interviews with air traffic controllers were utilized to develop an understanding of how interruptions occur in real ATC environments, and to identify where opportunities exist to use technology to support the interruption management process. It was identified that operators in these environments could better manage the effects of interruptions if there were indications to one operator of the availability of a collaborator and the urgency of an interruption from a collaborator. Present communication systems do not facilitate the awareness of these functionalities. An initial prototype for providing these functionalities in operational ATC displays was designed. Feedback on the prototypes was solicited through Participatory Design (PD) sessions with air traffic controllers. Based on the refinement of these prototypes, the Working Awareness Interruption Tool (WAIT) was developed to support more efficient and appropriate interruption timing in the context of complex, real-time, distributed, human operator interactions. Variations of the tool demonstrated several ways of showing the availability of the controller to be interrupted (either through manual settings or automatic detection) as well as incorporating a means of conveying the urgency level of the interruption. In order to examine the utility of the tool and to assess the importance and validity of its features, an experiment was conducted in a laboratory-based setting. The results of the experiment show the potential of this tool in an environment representative of air traffic control tasks and communication. Although the sample size was limited, the WAIT facilitated improved performance on both objective measures and self-reported measures, and reduced the distraction effects of interruptions from other operators. These improvements occurred without affecting perceptions of the effectiveness of communications. Questionnaire and interview results showed that participants appear to prefer an automated setting of availability to be shown to other collaborators. Identifying two examples of key features supporting interruption management (communicating availability and urgency) in air traffic control is one of the key contributions of this work. The work also makes a contribution by demonstrating that providing a tool incorporating these features can improve performance in an environment representative of ATC, albeit with naïve participants. Finally, the research makes a contribution by presenting the challenges associated with evaluating interruption management tools that require collaboration between operators in a system.
65

Neurointensivvårdspatientens förutsättningar för ett optimalt neurologiskt wake-up test : en observationsstudie

Eriksson, Charlotte, Hassmund, Cecilia January 2014 (has links)
Background: Examinations with the intent to assess neurological functions and level of conciousness are common in neurocritical care, but the effect on the patient is not entirely researched. Aim: The purpose of this study was to describe the patient’s situation at the neurological wake-up test concerning the environment, nursing interventions and the possibility given the patient to become awake, and if these conditions affect the outcome of the wake-up test. Methods: A quantitative observational study took place at a neurocritical care unit, where 20 patients were observed from interruption of sedation to the neurological assessment, which was performed by a neurosurgeon or a specialized critical care registered nurse. Nursing interventions, environmental factors and physiological parameters were documented. Result: Twelve intervention varieties to control patients’ physiological parameters were used. CPP > 80 mmHg was found in 90 % of observations. Adjustment of the patient’s body position was found in 45 % of observations. The patients were considered sufficiently awake for the neurological assessment in 74 % of observations. The level of consciousness at the point of the neurological assessment was different depending on if it took place in the mornings, performed by neurosurgeons or in the afternoon, performed by nurses. The patients were not agitated and 60 % of patients appeared pain-free. Conclusion: The observed patients were given good conditions concerning environmental factors and nursing interventions for a neurological wake-up test with a fair neurological assessment. NWT as a method didn´t generally cause the observed patients discomfort, such as pain or agitation. / Bakgrund: Undersökningar för att avgöra neurologisk funktion och medvetandegrad är vanliga inom neurointensivvården, men hur patienten påverkas av undersökningarna är relativt utforskat. Syfte: Studiens syfte var att beskriva förhållandena kring patienten vid neurologiskt wake-up test med avseende på miljö, åtgärder som utförs och möjligheten patienten ges att bli tillräckligt vaken, samt om dessa förhållanden påverkar utfallet i wake-up-testet. Metod: En kvantitativ observationsstudie genomfördes på en neurointensivvårdsavdelning, där 20 patienter observerades från sederingsstopp till bedömning av neurologisk status, vilken utfördes av neurokirurg eller intensivvårdssjuksköterska. Omvårdnadsåtgärder, miljöfaktorer och fysiologiska parametrar dokumenterades. Resultat: Tolv varianter av omvårdnadsåtgärder användes för att hålla patienternas fysiologiska parametrar inom gränsvärden. Högt CPP > 80 mmHg förekom i 90 % av observationerna och den omvårdnadsåtgärd som noterades vid flest observationer var justering av patientens kroppsposition (45 %). Vid 74 % av bedömningarna av neurologisk status ansågs patienten ha hunnit vakna tillräckligt mycket. Vakenhetsgraden vid bedömning av neurologisk status skilde sig åt beroende på om bedömningen utfördes på morgon av läkare eller på eftermiddag av intensivvårdssjuksköterska. Patienterna var inte agiterade och bedömdes vid 60 % av observationerna inte visa tecken på smärta innan bedömning av neurologisk status. Slutsats: Patienterna i studien gavs goda förutsättningar med avseende på miljö och omvårdnadshandlingar för ett neurologiskt wake-up test med rättvisande bedömning av neurologisk status. För de observerade patienterna var NWT en metod som generellt sett inte verkade orsaka obehag som smärta eller agitation.
66

Refinery Power Distribution Reliability and Interruption

Nygren, Leif 11 1900 (has links)
In the refining industry, the cost of a power system interruption is dominated by an associated loss of production. Power distribution within a refinery includes a set of production units within a highly inter-dependent process, where the outage of a single unit affects the production of additional units. This thesis proposes a method to quantify the impact of this cascading effect, called the criticality enhancement function, in which a process reliability model is introduced to link electrical outage cut-sets with lost production. Power system criticality is analyzed using four different approaches to the calculation of annual expected impact from load point interruptions on a case study of the 125,000 barrel-per-day Petro-Canada Edmonton Refinery. This thesis demonstrates how employment of the proposed technique, with its marriage of electrical and process reliability models, enables the most accurate estimation of the impact of power system interruptions.
67

La estructura lingüística del paréntesis en conversación informal la conexión entre el contexto conversacional y el contexto situacional /

Norgard, Christine A. January 2007 (has links)
Thesis (M.A.)--Miami University, Dept. of Spanish and Portuguese, 2007. / Title from first page of PDF document. Includes bibliographical references (p. 54-55).
68

Impact of an interrupted class period on students' academic achievement and attitudes

Jenkins, Robert Keith. Sabine, Creta D., January 1977 (has links)
Thesis (Ed. D.)--Illinois State University, 1977. / Title from title page screen, viewed Dec. 17, 2004. Dissertation Committee: Creta Sabine (chair), Elwood Egelston, Ronald Laymon, Larry Kennedy, Ronald Halinski. Includes bibliographical references (leaves 110-115) and abstract. Also available in print.
69

Marknadsstudie inför framtagande av nytt nätinformationssystem för Vimmerby Energi & Miljös elnät / Market study as preparation for a new grid information system for the electrical grid of Vimmerby Energi & Miljö AB

Lind, Daniel January 2015 (has links)
Arbetets syfte är att söka av marknaden efter befintliga nätinformationssystem för elnät, för att avgöra vilken funktioner Vimmerby Energi & Miljö AB anses behöva. Och vilket be-fintligt nätinformationssystem som bäst uppfyller de behoven.Efter en urvalsprocess, som baserades på vilken information som fanns att tillgå på respektive nätinformationssystems hemsidor. Samlades sedan data in med hjälp av demonstrationer.Utifrån demonstrationerna kunde det fastställas att alla nätinformationssystemen uppfyllde alla de grundläggande kraven på avbrottsrapportering och förhandsregleringsrapporter till EI. Samt att de alla hade väl utvecklade beräkningssystem, där de viktigaste ansågs vara kortslutningsströmmar och jordslutningsimpedanser.Tre av de redovisade systemen var helt grafiska, medan det fjärde som också är det befintliga systemet är tabellbaserat. Det visade sig dock att kunna utökas med en modul för grafisk visning av ledningarnas läge.Efter att ha undersökt de olika nätinformationssystemens arbetsmetoder, funktionalitet, styrkor och svagheter så kunde slutligen DigPros dpPower, ur en ren teknisk synvinkel, rekommenderas som det nätinformationssystem som bäst passar Vimmerby Energi & Miljö AB. Däremot visade sig Powel OpenNIS också vara ett mycket bra alternativ.Men då rapporten inte tar upp några kostnader i bedömningen så kan rekommendationen komma att förbises, då målet med rapporten främst är att identifieras Vimmerby Energi & Miljös behov, och att bedöma hur väl varje system uppfyller dessa. / This thesis investigates the market for current grid information system for electric grids, to determine which functions that are needed by Vimmerby Energi & Miljö AB. And also which grid information system that is best suited.The selection was based on information found on each grid information system's home-page. By means of demonstration data was collected from the selected grid information system, for comparison.From the comparison one could determine that all of the grid information systems did sat-isfy all the demands from Energimarknadsinspektionen concerning power outages and prior regulation of electrical grid tariffs. All of the grid information systems also satisfied the demands for grid calculations, primarily short circuit currents and earth fault imped-ances.Three of the presented grid information systems were purely graphical, whilst the fourth, which is the present grid information system, were table based. This could be supple-mented with a module for graphically displaying the positions of the lines on a map.By investigating the grid information systems work methods, functionality, strengths and weaknesses it was found that, from a purely technical perspective, the best choice would be DigPro's dpPower. Although Powel's OpenNIS proved to be a good alternative.Since the report only investigates the grid information systems from a technical perspec-tive, and therefore don't report on any of the cost of implementing or sustaining the grid information system, the recommended system might end up not being the best choice. This is mostly due to the purpose of the report, which is to investigate and find which type of functions that suite Vimmerby Energi & Miljö's need. And the recommended grid in-formation system is the one which is considered to satisfy most of these needs.
70

La sexualité des personnes handicapées / The sexuality of people with disabilities

Sellami, Sofia 23 March 2017 (has links)
La sexualité des personnes handicapées sort de l’ombre et fait actuellement l’objet de nombreuses réflexions pluridisciplinaires. Le temps est enfin venu aux juristes –et autres– de briser les tabous pour réfléchir à cette thématique que le législateur s’est abstenu de prendre en compte malgré les difficultés qu’elle pose. Les personnes handicapées ne disposent pas toujours des aptitudes pour avoir une sexualité qu’elles désirent. En revanche, elles subissent parfois une sexualité qu’elles ne veulent pas ou ne sont pas en mesure de vouloir. L’un de ces paradoxes conduit ainsi à l’étude de problèmes aussi divers que ceux relatifs à la procréation des personnes handicapées, à leur épanouissement sexuel ou aux agressions sexuelles dont elles sont généralement les victimes. / The sexuality of people with disabilities finally comes out of the shadows and is the subject of many multidisciplinary reflections.The time has finally come for legal experts –and others –to break taboos and to start reflecting on this issue that the legislator has been avoiding despite the difficulties it sets. People with disabilities do not always have the ability to have a sexuality that they desire. On the other hand, they sometimes experience sexuality that they do not want or are not able to want.One of these paradoxes thus leads to the study of problems as diverse as those related to the procreation of persons with disabilities, their sexual fulfillment or the sexual abuse of which they are generally the victims.

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