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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

A model for selecting a computerized maintenance system : -A case study

Glarner, Anna, Alsyouf, Ali January 2007 (has links)
The purpose of this master thesis is to develop a model for selecting a computerize Maintenance Management system CMMS. A literature survey for finding relevant theories using database Emerald was performed. The aim of the model is to select the best CMMS and it is a general model that could be used by any company to take the right decision for selecting the CMMS. In this thesis a case study has been performed for selecting the CMMS. The case company for this case study was Hammarplast AB in Tingsryd which is part of HammarplastGruppen. Ten years ago Hammarplast use to be very good in their preventive maintenance but since the production became more automatic and the people that work with maintenance also work with production development their maintenance have come behind. That is why Hammarplast are interested to have a CMMS that would help them to develop their maintenance performance. Four different CMMS (Movex, Dash vp, Tekla and Tribologen) has been analyzed by the authors. The choosing of CMMS was wishes from the case company. From our analyses we recommend Tekla as a CMMS to be used in the case company, since it satisfies the demand of the company by focusing on user friendly, cost, planning and improvement. But before buying Tekla the case company should try to investigate Movex more carefully. / Syftet med examensarbetet är att utveckla en modell för att välja ett datorbaserat underhållssystem (CMMS). En litteratur studie har utförts i databasen Emerald. Det är en generell modell som företag kan använda sig av och modellen strävar efter att välja den bästa CMMS. I detta arbete har en fallstudie utförts för att välja CMMS. Företaget som har används i fallstudien var Hammarplast i Tingsryd, som tillhör HammarplastGruppen. För tio år sedan var Hammarplast mycket duktiga på förebyggande underhåll men eftersom deras produktion blev mer automatisk och att personerna som arbetar med underhåll också arbetar med produktutveckling så har underhållet kommer efter. Därför är Hammarplast intresserade av att ha ett CMMS som hjälper dem utveckla deras underhåll. Fyra olika CMMS (Movex, Dash vp, Tekla och Tribologen) har analyserats av författarna. Valet av dessa CMMS var önskemål från företaget. Från analysen så rekommenderas Tekla som CMMS att använda i företaget, eftersom det tillfredställer kraven från företaget med fokus på användarvänlig, kostnad, planering och förbättring. Men innan anskaffning av Tekla bör en mer detaljerad utvärdering av Movex utföras.
62

Car Purchasing Behavior in Beijing : - An Empirical Investigation

Bai, Xuan, Dongyan, Liu January 2008 (has links)
This study aims to give an overview on young Chinese consumers’ car purchase behavior. The results show that car purchasing decision is an important decision for most of Chinese. Consumers get information from different channels. The results of this study also tells us that Chinese consumers take “safety” as the most important characteristic and take “value for money” as the second most important and “riding comfort” as the third important characteristic. Chinese consumers take “after-sale maintenance” and “exterior design/size” as the forth most important factors when making the purchase decision. For “exterior design/size”, it indicates that Chinese people are status-seeking and Chinese people prefer to choose a bigger car with a good appearance (Mian Zi Che) to show their good social status and want to get respects from others. Chinese consumers put the least importance on resale value that is because second hand car market is not well developed in China.
63

Simulation and Optimization of Wind Farm Operations under Stochastic Conditions

Byon, Eunshin 2010 May 1900 (has links)
This dissertation develops a new methodology and associated solution tools to achieve optimal operations and maintenance strategies for wind turbines, helping reduce operational costs and enhance the marketability of wind generation. The integrated framework proposed includes two optimization models for enabling decision support capability, and one discrete event-based simulation model that characterizes the dynamic operations of wind power systems. The problems in the optimization models are formulated as a partially observed Markov decision process to determine an optimal action based on a wind turbine's health status and the stochastic weather conditions. The rst optimization model uses homogeneous parameters with an assumption of stationary weather characteristics over the decision horizon. We derive a set of closed-form expressions for the optimal policy and explore the policy's monotonicity. The second model allows time-varying weather conditions and other practical aspects. Consequently, the resulting strategy are season-dependent. The model is solved using a backward dynamic programming method. The bene ts of the optimal policy are highlighted via a case study that is based upon eld data from the literature and industry. We nd that the optimal policy provides options for cost-e ective actions, because it can be adapted to a variety of operating conditions. Our discrete event-based simulation model incorporates critical components, such as a wind turbine degradation model, power generation model, wind speed model, and maintenance model. We provide practical insights gained by examining di erent maintenance strategies. To the best of our knowledge, our simulation model is the rst discrete-event simulation model for wind farm operations. Last, we present the integration framework, which incorporates the optimization results in the simulation model. Preliminary results reveal that the integrated model has the potential to provide practical guidelines that can reduce the operation costs as well as enhance the marketability of wind energy.
64

A Study on Taipei College Students¡¦ Consumer Behavior for Arts and Branding Commodities

Chen, Pei-Hsuan 06 February 2007 (has links)
With rapid change in social and economic surroundings in Taiwan, consumption behavior of Taiwanese changes gradually. College students maybe are the group that changes their behaviors significantly in this environment. They start to emphasize their ¡§personal style.¡¨ For most young people, purchasing is not only related to their needs, but also related to brands, design, and package. Therefore, how to combine ¡§arts¡¨ and ¡§brand¡¨ in order to attract young people¡¦s attention and satisfy their tastes is a key factor for enterprises in the future. After all, what interesting results will be generated if a product is included both ¡§art work¡¨ and ¡§a terrific brand¡¨? Will young people become the major consumers for those commodities? Are their consumer behaviors different from other groups? And what factors motive them to buy those products? These questions are discussed in this study. The purposes of this research are as follows: to understand young people¡¦s consumer behavior on commodities which are combination of art work and a brand; to understand what factors encourage young people to buy the product; and to make sure the acceptance of these communities in the market. Survey research was chosen as methodology in this research. The target population was college and graduate students in Taipei. Drop-off survey was major method for collecting data. Three hundred ninety-seven samples were sent out, 302 samples were returned, and 291 were valid. The valid response rate was 96.36%. According to the result, the acceptable degree in the market for these commodities was high. Clothing/Accessory, 3C, and sport products were the primary choices of young people. When college students purchased these commodities, they thought uniqueness and artistry were most important, and prices as well as quality were second important. Regarding to sales promotion, young people preferred discount and limit edition. Reasons for buying these commodities were to please themselves and enjoy the design. Most young people would buy these commodities because of their brands; however they also cared about the impression and style of artists.Generally speaking, young people showed positive attitudes and sound impressions for the corporation between artists and brands.
65

A model for selecting a computerized maintenance system : -A case study

Glarner, Anna, Alsyouf, Ali January 2007 (has links)
<p>The purpose of this master thesis is to develop a model for selecting a computerize Maintenance Management</p><p>system CMMS. A literature survey for finding relevant theories using database Emerald was performed. The aim</p><p>of the model is to select the best CMMS and it is a general model that could be used by any company to take the</p><p>right decision for selecting the CMMS.</p><p>In this thesis a case study has been performed for selecting the CMMS. The case company for this case study</p><p>was Hammarplast AB in Tingsryd which is part of HammarplastGruppen. Ten years ago Hammarplast use to be</p><p>very good in their preventive maintenance but since the production became more automatic and the people that</p><p>work with maintenance also work with production development their maintenance have come behind. That is</p><p>why Hammarplast are interested to have a CMMS that would help them to develop their maintenance</p><p>performance.</p><p>Four different CMMS (Movex, Dash vp, Tekla and Tribologen) has been analyzed by the authors. The choosing</p><p>of CMMS was wishes from the case company. From our analyses we recommend Tekla as a CMMS to be used</p><p>in the case company, since it satisfies the demand of the company by focusing on user friendly, cost, planning</p><p>and improvement. But before buying Tekla the case company should try to investigate Movex more carefully.</p> / <p>Syftet med examensarbetet är att utveckla en modell för att välja ett datorbaserat underhållssystem (CMMS). En</p><p>litteratur studie har utförts i databasen Emerald. Det är en generell modell som företag kan använda sig av och</p><p>modellen strävar efter att välja den bästa CMMS.</p><p>I detta arbete har en fallstudie utförts för att välja CMMS. Företaget som har används i fallstudien var</p><p>Hammarplast i Tingsryd, som tillhör HammarplastGruppen. För tio år sedan var Hammarplast mycket duktiga på</p><p>förebyggande underhåll men eftersom deras produktion blev mer automatisk och att personerna som arbetar</p><p>med underhåll också arbetar med produktutveckling så har underhållet kommer efter. Därför är Hammarplast</p><p>intresserade av att ha ett CMMS som hjälper dem utveckla deras underhåll.</p><p>Fyra olika CMMS (Movex, Dash vp, Tekla och Tribologen) har analyserats av författarna. Valet av dessa CMMS</p><p>var önskemål från företaget. Från analysen så rekommenderas Tekla som CMMS att använda i företaget,</p><p>eftersom det tillfredställer kraven från företaget med fokus på användarvänlig, kostnad, planering och förbättring.</p><p>Men innan anskaffning av Tekla bör en mer detaljerad utvärdering av Movex utföras.</p>
66

Kartläggning av upphandlingsprocessen inom vatten- och avloppsbranschen – användning av livscykelkostnader i processen / Mapping of the procurement process within the water and wastewater trade - the use of life-cycle costs of the process

Carlsson, Stefan January 2015 (has links)
Syftet med offentlig upphandling är att konkurrensutsätta marknader och skapa bästa möjligaaffär för de offentliga medel som den upphandlande myndigheten har till sitt förfogande.Offentlig upphandling ska ske med långsiktigt perspektiv och det finns verktyg för att tillse attett långsiktigt synsätt erhålls. Ett av dessa verktyg är livscykelkostnader (LCC) som beaktaren produkts anskaffning, ägande och avveckling. En produkt som har ett högtanskaffningsvärde men låga framtida kostnader, kan bli det mest kostnadseffektiva inköpet.LCC används för att göra en ekonomisk värdering av olika investeringsalternativ,diskonterade över produktens livslängd. Livscykelkostnader är ett synsätt som utforskar deolika investeringsalternativen och används aktivt för att föra en dialog mellan aktörerna iupphandlingsprocessen. Användningen av livscykelkostnader, kan antas vara till god hjälp för beslutsfattarna i vattenoch avloppsbranschen (VA) om de vill ta långsiktigt korrekta beslut. Problematiken är attingen har kartlagt hur ett livscykelkostnadsverktyg påverkar beslutsprocessen i offentligaupphandlingar inom VA-branschen och om det ger beställaren ett tydligt beslutsstöd. Dennastudie syftade därför att ta reda på hur livscykelkostnader används i praktiken och hur enanalys av livscykelkostnader bättre kan stödja beslutsprocessen för offentliga upphandlingarinom VA. Studien syftade även till att ta reda på hur ett livscykelkostnadsverktyg bör varautformat, genom att ge förslag på förutsättningar som måste tas hänsyn till. Detta examensarbete har utförts på uppdrag av Vattenreningsindustrins mötesplats (VARIM).En kvalitativ intervjustudie genomfördes, uppdelad i två faser, med 27 stycken intervjuer somgav upphov till ett rikt material. Intervjupersonerna hade fem olika aktörsroller: beställare,upphandlare, brukare, konsult och anbudsgivare. Studien avgränsades till att endast undersökafyra kommuntyper: storstäder, större städer, varuproducerande kommuner ochglesbygdskommuner. Resultatet från datainsamlingen analyserades med utgångspunkt i teorinfrån litteraturstudien. Resultaten visar att det finns ett stort behov av att använda livscykelkostnader iVA-upphandlingar. Det finns även stor potential för LCC-användande då majoriteten avintervjupersonerna ställde sig positiva till användandet av LCC, primärt vid upphandling avenergiförbrukande produkter eller processer. En stor resursskillnad identifierades mellanmindre beställare och större beställare, vilket resulterar i att de mindre beställarna inteanvänder livscykelkostnader som ett tilldelningskriterium. Resultaten pekar på attanvändningen av livscykelkostnader bidrar till ökad transparens i upphandlingsprocessen ochleder därför till en mindre risk för överprövning. Uppföljning av livscykelkostnader i kontraktär ett av de svåraste problemen visar studien. / The purpose of public procurement is to create competitive markets and generate the bestpossible deal for the contracting authority. Public procurement should aim for long-termperspective, and there are tools to ensure that a long-term view is obtained. One tool is lifecycle costs (LCC), where product acquisition, ownership and settlement are considered. Aproduct that has a high investment cost but low operating costs, may be the most costeffectivepurchase. LCC is used to achieve an economic evaluation of different investmentoptions, discounted over the lifetime of the product. Life-cycle costing is an approach thatexplores the various investment options and is used to as a basis of discussion by theparticipants in the procurement process. The use of life-cycle costs, are expected to be useful for decision makers in the water andwastewater industry if they want to take long-term correct decisions. The problem is that noone has studied how a life cycle cost tool affects the decision-making process in publicprocurement within the water and wastewater industry and if it gives the client a gooddecision making basis. This study therefore aimed to find out how life cycle costs are used inpractice and how these can be used in practice, as an aid in the decision making process forwater and wastewater procurements. The study also aimed to find out how a life cycle costtool should be designed, by giving suggestions on conditions that must be taken into account. This thesis has been carried out on behalf of The meeting place for the industry in watertreatment (VARIM), with the aim to investigate the procurement process within the water andwastewater trade. It also studies how life cycle costs are used in the process. The study wascarried out in two steps, consisting of qualitative interviews, 27 individual interviews gaverise to a rich material, which was subject to further analysis. The interviewees had fivedifferent roles in the procurement process: client, purchaser, user, consultant and bidder. Thestudy was limited to investigating four types of municipalities: large cities, major cities,manufacturing municipalities and rural municipalities. The results from the interviews wereanalyzed based on theory from the literature study, the results from the data collection wereanalyzed. The results show that life-cycle costs in water and wastewater procurement are needed. Thereis also great potential for LCC as the majority of respondents were in favor of the use of LCC,primarily in the procurement of energy-using products or processes. A great difference inaccess to resources was identified between smaller clients and major clients, resulting in thesmaller clients not using life-cycle costs as a criterion. Also the results indicate that the use oflife cycle costs contributes to greater transparency in the procurement process and thereforedecreases risk of appeals. The study shows that follow up of life cycle cost in a contract is oneof the most difficult problems in procurement.
67

Adaptive routing in schedule based stochastic time-dependent transit networks

Rambha, Tarun 29 October 2012 (has links)
In this thesis, an adaptive transit routing (ATR) problem in a schedule based stochastic time-dependent transit network is defined and formulated as a finite horizon Markov Decision Process (MDP). The transit link travel times are assumed to be random with known probability distributions. Routing strategies are defined to be conditional on the arrival times at intermediate nodes, and the location and arrival times of other buses in the network. In other words, a traveler in the network decides to walk, wait or board a bus based on the real time information of all buses in the network. The objective is to find a strategy that minimizes the expected travel time, subject to constraints that guarantee that the destination is reached within a certain threshold. The value of the threshold was chosen to reflect the risk averse attitude of travelers and is computed based on the earliest time by which the destination can be reached with probability 1. The problem inherits the curse of dimensionality and state space reduction through pre-processing is achieved by solving variants of the time dependent shortest path problem. An interesting analogy between the state space reduction techniques and the concept of light cones is discussed. A dynamic program framework to solve the problem is developed by defining the state space, decision space and transition functions. Numerical results on a small instance of the Austin transit network are presented to investigate the extent of reduction in state space using the proposed methods. / text
68

Why consumers engage in eWOM : motivation to conduct research online and post online reviews / Varför konsumenter engagerar sig i eWOM : motivation till att nyttja information på nätet och skapa onlinerecensioner

Lulek, Alexandra, Wehinger, Marcus January 2015 (has links)
The purpose of this study was to provide a better understanding why consumers conduct research online and post online reviews. This was achieved by finding relationships between the two phenomena presented above. The study used a cross-sectional design since little was known about the relationships within the chosen research area. Results were measured by quantitative instrument through a self-administered questionnaire divided by each phenomenon. The questionnaire was directed towards Swedish consumers in the buying decision process.Consumers conduct research online with the specific goal for gaining information posted by other consumers, since it has a higher credibility. Helping other consumers and self-expression was reasons found in relation to why consumers post online reviews.Findings strengthen the fact that higher education could be found of relationship to conduct research online; however, not to post online reviews. In comparison to previous studies the study measured online shopping frequency instead of Internet experience. It was found that consumers who conducted online shopping were in relation with previous presented theories. / Syftet med denna studie var att skapa en bättre förståelse till varför konsumenter publicerar och konsumerar onlinerecensioner. Genom att applicera en tvärsnittsdesign kunde syftet uppnås då relationer identifierades. För att möjliggöra mätning av resultatet applicerades ett kvantitativt instrument genom en självadministrerad enkät vilken var uppdelad efter respektive fenomen.Onlinerecensioner används för det specifika målet att samla större mängder information innan köpbeslut. De onlinerecensioner som används främst är de skapade av andra konsumenter då de anses vara av högre trovärdighet än information skapat av företag. Att hjälpa andra konsumenter och självförbättring är vad resultatet påvisar vara anledning till att konsumenter publicerar onlinerecensioner.Vidare stärkte resultatet en relation där konsumenter med högre utbildning tenderar att konsumera onlinerecensioner men inte till att publicera dessa. Konsumenternas köpfrekvens applicerades istället för att mäta graden erfarenhet av Internet, vilket gjorts i tidigare studier.
69

FASTER DYNAMIC PROGRAMMING FOR MARKOV DECISION PROCESSES

Dai, Peng 01 January 2007 (has links)
Markov decision processes (MDPs) are a general framework used by Artificial Intelligence (AI) researchers to model decision theoretic planning problems. Solving real world MDPs has been a major and challenging research topic in the AI literature. This paper discusses two main groups of approaches in solving MDPs. The first group of approaches combines the strategies of heuristic search and dynamic programming to expedite the convergence process. The second makes use of graphical structures in MDPs to decrease the effort of classic dynamic programming algorithms. Two new algorithms proposed by the author, MBLAO* and TVI, are described here.
70

Active Sensing for Partially Observable Markov Decision Processes

Koltunova, Veronika 10 January 2013 (has links)
Context information on a smart phone can be used to tailor applications for specific situations (e.g. provide tailored routing advice based on location, gas prices and traffic). However, typical context-aware smart phone applications use very limited context information such as user identity, location and time. In the future, smart phones will need to decide from a wide range of sensors to gather information from in order to best accommodate user needs and preferences in a given context. In this thesis, we present a model for active sensor selection within decision-making processes, in which observational features are selected based on longer-term impact on the decisions made by the smart phone. This thesis formulates the problem as a partially observable Markov decision process (POMDP), and proposes a non-myopic solution to the problem using a state of the art approximate planning algorithm Symbolic Perseus. We have tested our method on a 3 small example domains, comparing different policy types, discount factors and cost settings. The experimental results proved that the proposed approach delivers a better policy in the situation of costly sensors, while at the same time provides the advantage of faster policy computation with less memory usage.

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