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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.
101

Identifying critical components for system reliability in power transmission systems

Setréus, Johan January 2011 (has links)
Large interruptions of power supply in the transmission system have considerable impact on modern society. The goal for the transmission system operator (TSO) is to prevent and mitigate such events with optimal decisions in design, planning, operation and maintenance. Identifying critical power components for system reliability provides one important input to this decision-making. This thesis develops quantitative component reliability importance indices applicable for identifying critical components in real transmission systems. Probabilistic models with component failure statistics are combined with detailed power system models evaluated with the AC power flow technique. In the presented method each system component is assigned three importance indices based on outage events expected probability and consequence to (i) reduced system security margin, (ii) interrupted load supply and (iii) disconnected generation units. By ranking components by each of the three interests, a more complete view of the risks to system reliability can be assessed than if, as traditionally, only (ii) is modelled. The impact on security margin is studied in well established critical transfer sections (CTS) supervised by the TSO. TSOs set the CTSs limits [MW] based on deterministic security criteria, with regard to thermal, voltage level, and system stability limits, and the CTSs' condition at post-contingency state is in the method used as an indicator of the system security margin. The methodology is extended with three indices modified to quantify the component importance for common-cause events initiated by acts of sabotage. The developed methods are applied on a significant part of the Great Britain transmission system, modelling 7000 components and 107 substation layouts. The study includes several load demand scenarios, 200 million initiating outage events and non-functioning protection equipment. The resulting component ranking provides an important input to the TSO's decision-making, and could be implemented as a complement to the existing deterministic N-1 criterion. With the methods applied a TSO can perform further and more detailed assessments on a few critical components in order to enhance system reliability for equipment failures and strengthen the system vulnerability against sabotage. / QC 20110920
102

En rörig historia : en fallstudie över Secorocs processflöde av DTH-rör

Forsman, Kristoffer January 2010 (has links)
Abstract  Title: A messy story – a case study of Secorocs process flow of DTH-pipes  Presentation date: 2010-06-02  Course: Bachelor thesis in business Author: Kristoffer Forsman Advisor: Kjell Gustafsson Keywords: Management control, process control, lean production, process flow analysis Purpose: The purpose of this bachelor thesis is to develop an overview of the process flow for a specific product, and with the help of this mapping based on a lean production philosophy show possible improvement proposals and how these can lead to a more efficient process flow. Methodology: I have used a case study of Secorocs DTH-pipes and my primary data are gathered through interviews and observations. I have used theoretical framework to establish a process flow analysis. This is to obtain data on process activities and whether they are creating value or not. This leads to a current mapping of the situation in Secoroc on DTH-pipes and then analyzed and suggestions for improvement are developed. Conclusions: That by using the above mentioned mapping of process flow of DTH-pipes, problem areas could be illustrated. Subsequently proposals for improvement could be produced from a lean production philosophy. Process flow analysis showed the non-value-adding process activities as primarily transport and delay. These activities could be rationalized and eliminated from developed proposals for improvement which resulted in a layout flowchart (bilaga3) as a proposal on how a better flow might look for Secoroc.
103

Uranium Mining Industry : -A valuation of uranium mining companies

Östlund, Jacob, Kierkegaard, Kristian January 2007 (has links)
Background: Over the last three years uranium prices have soard from US $14 per pound (lb) to the current price of US $120/lb and this rapid incline of the commodity have created a boom within the uranium prospecting and min-ing industry. There are currently 435 nuclear reactors all over the world and these reactors demand 180 millions of pounds of uranium each year to run at full production. Currently the uranium mining industry only sup-plies 110 million pounds of the demanded quantity. The remaining 70 mil-lion pounds are coming from secondary sources such as decommissioned nuclear warheads and other sources. Market estimations say that the sec-ondary sources will only cover the shortage up until around 2012 then primary sources have to supply almost the whole quantity demanded. These factors imply that some sort of analysis model for uranium mining companies would be needed. Purpose: The purpose of this report is to valuate three companies within the ura-nium industry and to establish if the current market value is coherent with the fundamental value of these companies. The authors will propose a valuation model that could be used when valuating companies within the uranium industry. Method: A qualitative method has been used in order to value three companies within the uranium mining business that are fairly large players on the market. The valuation of these companies is based upon a discounted cash flow analysis, a relative PV valuation and relative valuation. The compa-nies included in the report are corporations that are quoted at Toronto Stock Exchange and they have started mining uranium. Data have been collected through annual reports and the companies Internet pages. Other secondary information such as valuation theories has been collected from academic search engines and books on the subjects. Conclusions: The current market values of uranium mining companies are not coherent with the actual fundamental values according to the authors. Both funda-mental and a comparative approach could be used when valuing these companies and the most important part in the valuation is to try and fore-cast the commodity price and then to estimate the companies possible mining reserve/extractable resources.
104

Produktivitetsanalys i hyvelanläggningen vid Chemwood AB i Alvesta

Karlsson, Erik, Ström, Christian January 2008 (has links)
Produktivitet kan inom tillverkande industri användas som ett nyckeltal för mått på effektivitet; enkelt uttryckt hur bra man utnyttjar tillgängliga resurser för att skapa god avkastning. För att öka produktiviteten bör man identifiera och eliminera, alternativt minska risken för störningar i flödet. Bland störningar återfinns bland annat ställtid och justeringar. Genom att reducera tiden för omställning av maskinutrustning ökar tillgänglig produktionstid liksom flexibiliteten i produktsortimentet. Syftet med studien är att identifiera och belysa produktivitetshämmande företeelser och ge förslag till produktivitetshöjande åtgärder för och vid postning såväl för hela flödet vid Chemwood AB i Alvesta. Utöver närmare studie av postningsförfarandet identifierades och analyserades även andra för flödet störande företeelser. Postningsförfarandet vid Chemwood AB kan enbart normeras till den grad där grundläggande moment ingår. Tiden för postning kan reduceras genom enkla åtgärder. / Productivity can within production be regarded as a tool of measuring efficiency – simply put how well you use available resources in order to create value and high yield. In order to increase productivity thou should aim at identifying and if possible eliminate the risk of disturbances in the line of production. Amongst disturbances one can see setup times and adjustments. By reducing the time of setup in the planing equipment the available time for production as well as the flexibility in product assortment increases. The purpose of the study is to identify and elucidate restraints and provide suggestions of improvement for the entire flow; particularly measures for reducing setup time in the planer. The setup procedure at Chemwood AB in Alvesta can be standardised to a level where basic elements are included. The setup time can without difficulty be reduced.
105

Flödesanalys hos Anders Karhner AB

Gustafsson, Marcus, Ferm, Robert January 2006 (has links)
Denna rapport har utförts hos Anders Krahner AB i Skillingaryd som ingår i koncernen Proton Group AB. År 2005 omsatte Proton Group 920 mkr med 730 anställda medan Anders Krahner omsatte 160 mkr med 90 anställda. Anders Krahners kunder finns främst inom fordonsindustrin. Syftet med rapporten är att studera om möjlighet finns att optimera produktionsflödet för två artiklar i befintliga lokaler. Genom att studera vad som påverkar genomloppstiden för artiklarna negativt kunna ge förslag på hur detta kan förbättras. Frågan är om detta kan ske i dagens lokaler eller är nybyggnation enda sättet att effektivisera produktionsflödet. Studien har skett från råvarulager till det att slutartikeln levereras till kund. All data i rapporten är hämtad ur Anders Krahners MPS system och baseras på ett års underlag. Ur dessa data har genomsnittstiderna för processtider och lagertider beräknats. Likaså har de planerade tiderna för operationerna erhållits ur MPS systemet. För att få förståelse för materialflödet i produktionen har layoutflödesscheman skapats. Genom analys av dessa har de totala interntransportsträckorna beräknats. I resultatet framgår det att de planerade operationstiderna stämmer väl överens med de verkliga tiderna. Detta visar på att operationerna fungerar väl ur ett tidsperspektiv, dock finns det vissa kvalitetsbrister. Det som påverkar genomloppstiden mest i negativ riktning är tiden för råvaru- och mellanlager. Ytterligare en bidragande orsak till den långa genomloppstiden är de komplicerade interntransporterna. Vidare orsaker till den komplexa interntransporten är att närhet mellan olika operationsmoment saknas idag. En del av de operationer som utförs för att färdigställa artiklarna sker på legoproduktion. Dessa tillverkningsmoment skapar en del av de komplicerade interntransporterna. För att skapa närhet mellan de olika operationerna har nya layouter skapats i den befintliga lokalen. En del av de operationer som sker på outsourcing har tagits hem för att ske i egen regi. Detta för att erhålla större kontroll över det totala flödet och öka kvalitén. Den skillnad som uppstår mellan layouterna i den befintliga lokalen jämfört med ny anses vara små då det finns potential i den nuvarande. / This report has been performed at Anders Krahner AB in Skillingaryd which is a part of Proton Group AB. Year 2005 Proton Group had a turnover of 920 smkr with 730 employees while Anders Krahners turnover was 160 smkr with 90 employees. Anders Krahners customers are mostly within the automobile industry. The aim of this report is to study the possibility to optimize the production flow for two articles in the existing premises. By studying the factors that have a negative impact on the throughput time give proposal of how this can overcome. The question is if this can be done in existing premises or if a new premise is required. The study has been made from raw material stock until the delivery of the end product to the customer. All the facts have been required from Anders Krahners MPS system and are based on one year’s basis. The average time for the processes and the stock has been calculated from this data. The planed times for the operations has also been collected from their MPS system. To gain an understanding for the production a layout flowchart has been made. Throughout analysis of these the total internal transport stretch has been calculated. It is shown in the result that the planed operation times equal the actual operation times quite well. This interpret that the operations works well out of a time perspective, but there is a lack of quality at the products. A thing that influences the throughput time negative is the time for raw material- and middle material stock. More reasons to the complex internal transport today are the lack of nearness between operations. A part of the operations that are made in the process in completing the articles are made external. These operations create some of the complicated internal logistics. To create the wanted nearness between the operations new layouts have been created in the existing premises. Some of the operations that are made external before have been suggested to be made in house. Due to this a greater control over the entire flow is received and higher product quality. The main difference between the suggested layout in the existing premises and a new one is considered to be small.
106

Assessment Of Water Supply Impacts For A Mine Site In Western Turkey

Agartan, Elif 01 June 2010 (has links) (PDF)
A certain amount of water is required for a mine site located in Turgutlu in Western Turkey to be used in mining processes. The purpose of this study is to assess the impacts associated with meeting water supply requirements for the mine. Scope of the study involves determination of the alternative water resources, the assessment of impacts associated with each resource and the selection of the most feasible alternative in the aspect of environmental and technical effects. Three alternatives suggested to supply mine process water are surface water, groundwater and reuse of waste water of Turgutlu town after treatment. A low flow analysis of Gediz River was conducted for the evaluation of the surface water. For the groundwater alternative, Turgutlu-Salihli aquifer model was established using MODFLOW 2009.1 software and the impacts on groundwater resources were evaluated. The evaluation of the last alternative, reuse of waste water of Turgutlu after treatment, was based upon the amount of waste water generated and treatment needed. Results of the alternatives show that each alternative is applicable to supply the required water to the mine site. However, the storage of the Gediz River water in a v small dam in wet seasons to be used later in dry seasons and the reuse of waste water of Turgutlu after treatment are the alternatives with least impacts on existing water users and related ecosystems.
107

The Study of Load Characteristics in Taipower and Its Effect on Power System Operation

Kang, Meei-Song 06 July 2001 (has links)
Based on the load survey study, a stratified sampling method is proposed to select the proper size of customers so that the load patterns derived can represent the load behavior of whole customer population. In this study there are 1315 customers out of Taipower customers over various service classes are selected for the installation of intelligent meters in the field to measure the power consumption within every 15 minutes. The bad data detection is performed to identify the abnormal power consumption by executing the Chi-square test. The standardized daily load pattern of each customer class has been derived with the mean per-unit method of customer load. The billing data are retrieved from the customer information system and applied to derive the customer daily load pattern by considering the customer load patterns. According to the total power consumption by all customers within the same class and considering the corresponding daily load pattern, the daily load profile of the customer class is then determined. By aggregating the load profiles of all customer classes, the daily load composition and load model of each service district can therefore be solved. By the same manner, the daily load pattern of whole Taipower system can be derived and it can be used to support the proper design of tariff structure according to the respective contribution of system power demand by each customer class. To investigate the overloading of distribution main transformers during the summer season, the correlations analysis of customer power consumption and temperature is performed. The effect of temperature change to the power consumption of each customer class is solved by multiple regression analysis with 95% confidential level. Based on the temperature sensitivity and the corresponding load composition, the load change due to temperature rise for various customer classes can be estimated. To demonstrate the impact of temperature change to distribution system operation, considering the temperature sensitivity of power consumption and load composition solves the power demand at each load bus. By updating the bus load demand due to temperature change, the feeder loading and power loss is therefore derived. To resolve the over loading problem of distribution feeders and main transformers during the summer season, a temperature adaptive switching operation has been proposed to perform the proper load transfer among the feeders/main transformers. In this dissertation, the effect of temperature change to the time varying characteristics of load buses and power transmission in Taipower is investigated. The dc circuit model of Taipower system and the temperature effect of customer power consumption are considered in the stochastic load flow analysis. With the temperature rise, the power demand of northern buses is increased dramatically and more power has to be transmitted from the southern region. The large voltage angle difference is significantly various between system buses during the summer peak period. It is suggested that the safety margin assessment of system operation has to be executed by considering the temperature effect to the bus loading of power systems.
108

Comprehensive Path-sensitive Data-flow Analysis

Thakur, Aditya 07 1900 (has links)
Data-flow analysis is an integral part of any aggressive optimizing compiler. We propose a framework for improving the precision of data-flow analysis in the presence of complex control-flow. We initially perform data-flow analysis to determine those control-flow merges which cause the loss in data-flow analysis precision. The control-flow graph of the program is then restructured such that performing data-flow analysis on the resulting restructured graph gives more precise results. The proposed framework is both simple, involving the familiar notion of product automata, and also general, since it is applicable to any forward or backward data-flow analysis. Apart from proving that our restructuring process is correct, we also show that restructuring is effective in that it necessarily leads to more optimization opportunities. Furthermore, the framework handles the trade-off between the increase in data-flow precision and the code size increase inherent in the restructuring. We show that determining an optimal restructuring is NP-hard, and propose and evaluate a greedy heuristic. The framework has been implemented in the Scale research compiler, and instantiated for the specific problems of Constant Propagation and Liveness analysis. On the SPECINT 2000 benchmark suite we observe an average speedup of 4% in the running times over Wegman-Zadeck conditional constant propagation algorithm and 2% over a purely path profile guided approach for Constant Propagation. For the problem of Liveness analysis, we see an average speedup of 0.8% in the running times over the baseline implementation.
109

Flödesanalys hos Anders Karhner AB

Gustafsson, Marcus, Ferm, Robert January 2006 (has links)
<p>Denna rapport har utförts hos Anders Krahner AB i Skillingaryd som ingår i koncernen Proton Group AB. År 2005 omsatte Proton Group 920 mkr med 730 anställda medan Anders Krahner omsatte 160 mkr med 90 anställda. Anders Krahners kunder finns främst inom fordonsindustrin.</p><p>Syftet med rapporten är att studera om möjlighet finns att optimera produktionsflödet för två artiklar i befintliga lokaler. Genom att studera vad som påverkar genomloppstiden för artiklarna negativt kunna ge förslag på hur detta kan förbättras. Frågan är om detta kan ske i dagens lokaler eller är nybyggnation enda sättet att effektivisera produktionsflödet. Studien har skett från råvarulager till det att slutartikeln levereras till kund.</p><p>All data i rapporten är hämtad ur Anders Krahners MPS system och baseras på ett års underlag. Ur dessa data har genomsnittstiderna för processtider och lagertider beräknats. Likaså har de planerade tiderna för operationerna erhållits ur MPS systemet. För att få förståelse för materialflödet i produktionen har layoutflödesscheman skapats. Genom analys av dessa har de totala interntransportsträckorna beräknats.</p><p>I resultatet framgår det att de planerade operationstiderna stämmer väl överens med de verkliga tiderna. Detta visar på att operationerna fungerar väl ur ett tidsperspektiv, dock finns det vissa kvalitetsbrister. Det som påverkar genomloppstiden mest i negativ riktning är tiden för råvaru- och mellanlager. Ytterligare en bidragande orsak till den långa genomloppstiden är de komplicerade interntransporterna. Vidare orsaker till den komplexa interntransporten är att närhet mellan olika operationsmoment saknas idag. En del av de operationer som utförs för att färdigställa artiklarna sker på legoproduktion. Dessa tillverkningsmoment skapar en del av de komplicerade interntransporterna.</p><p>För att skapa närhet mellan de olika operationerna har nya layouter skapats i den befintliga lokalen. En del av de operationer som sker på outsourcing har tagits hem för att ske i egen regi. Detta för att erhålla större kontroll över det totala flödet och öka kvalitén. Den skillnad som uppstår mellan layouterna i den befintliga lokalen jämfört med ny anses vara små då det finns potential i den nuvarande.</p> / <p>This report has been performed at Anders Krahner AB in Skillingaryd which is a part of Proton Group AB. Year 2005 Proton Group had a turnover of 920 smkr with 730 employees while Anders Krahners turnover was 160 smkr with 90 employees. Anders Krahners customers are mostly within the automobile industry.</p><p>The aim of this report is to study the possibility to optimize the production flow for two articles in the existing premises. By studying the factors that have a negative impact on the throughput time give proposal of how this can overcome. The question is if this can be done in existing premises or if a new premise is required. The study has been made from raw material stock until the delivery of the end product to the customer.</p><p>All the facts have been required from Anders Krahners MPS system and are based on one year’s basis. The average time for the processes and the stock has been calculated from this data. The planed times for the operations has also been collected from their MPS system. To gain an understanding for the production a layout flowchart has been made. Throughout analysis of these the total internal transport stretch has been calculated.</p><p>It is shown in the result that the planed operation times equal the actual operation times quite well. This interpret that the operations works well out of a time perspective, but there is a lack of quality at the products. A thing that influences the throughput time negative is the time for raw material- and middle material stock. More reasons to the complex internal transport today are the lack of nearness between operations. A part of the operations that are made in the process in completing the articles are made external. These operations create some of the complicated internal logistics.</p><p>To create the wanted nearness between the operations new layouts have been created in the existing premises. Some of the operations that are made external before have been suggested to be made in house. Due to this a greater control over the entire flow is received and higher product quality. The main difference between the suggested layout in the existing premises and a new one is considered to be small.</p>
110

Produktivitetsanalys i hyvelanläggningen vid Chemwood AB i Alvesta

Karlsson, Erik, Ström, Christian January 2008 (has links)
<p>Produktivitet kan inom tillverkande industri användas som ett nyckeltal för mått på effektivitet; enkelt uttryckt hur bra man utnyttjar tillgängliga resurser för att skapa god avkastning. För att öka produktiviteten bör man identifiera och eliminera, alternativt minska risken för störningar i flödet. Bland störningar återfinns bland annat ställtid och justeringar. Genom att reducera tiden för omställning av maskinutrustning ökar tillgänglig produktionstid liksom flexibiliteten i produktsortimentet.</p><p>Syftet med studien är att identifiera och belysa produktivitetshämmande företeelser och ge förslag till produktivitetshöjande åtgärder för och vid postning såväl för hela flödet vid Chemwood AB i Alvesta. Utöver närmare studie av postningsförfarandet identifierades och analyserades även andra för flödet störande företeelser.</p><p>Postningsförfarandet vid Chemwood AB kan enbart normeras till den grad där grundläggande moment ingår.</p><p>Tiden för postning kan reduceras genom enkla åtgärder.</p> / <p>Productivity can within production be regarded as a tool of measuring efficiency – simply put how well you use available resources in order to create value and high yield. In order to increase productivity thou should aim at identifying and if possible eliminate the risk of disturbances in the line of production. Amongst disturbances one can see setup times and adjustments. By reducing the time of setup in the planing equipment the available time for production as well as the flexibility in product assortment increases.</p><p>The purpose of the study is to identify and elucidate restraints and provide suggestions of improvement for the entire flow; particularly measures for reducing setup time in the planer.</p><p>The setup procedure at Chemwood AB in Alvesta can be standardised to a level where basic elements are included. The setup time can without difficulty be reduced.</p>

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