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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.
31

Resource Allocation on the MISO Interference Channel

Lindblom, Johannes January 2010 (has links)
The need for wireless communications has increased during the last decades. To increase the data rates of the communication links there is a need of allocating larger frequency bands. These bands are strictly regulated and the majority of the frequencies are allocated to licensed systems. The splitting of the bandwidth is orthogonal, which mean that the different systems are not interfering each other. But, orthogonal splitting is inefficient since it does not exploit all degrees of freedom in the wireless channels. There are also unlicensed bands where different systems co-exist and operate simultaneously in a non-orthogonal manner and interfere each other. This interference degrades the performance of each system. This motivates the use of so-called spectrum sharing techniques for interference management. The spectrum sharing can be modeled via the so-called interference channel (IFC). This consists of at least two transmitter (TX)-receiver (RX) pairs. These pairs can share resources such as frequency, time, power, code, or space. Here, the focus is on the sharing of spatial resources. By employing multiple antennas at the TXs, spatial diversity is obtained and it is possible to steer the power in any spatial direction. Assuming a single antenna at each RX we get the so-called multiple-input single-output (MISO) IFC. There is a conflict inherent in the IFC since the TX-RX pairs optimize conflicting objectives, e.g., the data rates. To analyze this conflict we use game-theoretic concepts. In general, the situation where the TXs transmit in the directions which are optimal for their objective is inefficient. That is, it is possible increase all rates of some (or all) TX-RX pairs without decreasing the rate of any of the pairs. To do so, the TXs change their strategies such that interference is decreased. We define several rate regions, which depend on the channel model and channelstate information at the transmitters. Also, some of the most important game-theoretic operating points are described.
32

Polarization characteristics in polyelectrolyte thin film capacitors : Targeting field-effect transistors and sensors

Larsson, Oscar January 2009 (has links)
Polymers are very attractive materials that can be tailored for specific needs and functionality. They can for instance be made electrically insulating or (semi)conducting, with specific mechanical properties. Polymers are often processable from a solution, which enables the use of low-cost manufacturing techniques to fabricate polymer devices. Polymer-based electronic and electrochemical devices and sensors have been developed. This thesis is related to the polarization characteristics in polyelectrolyte thin film capacitor structures. The polarization characteristics have been analyzed at various humidity levels for polyelectrolyte capacitors alone and when incorporated as the gate-insulating material in polyelectrolyte-gated organic field-effect transistors. Both limitations and possibilities of this class of transistors have been identified. Also, a concept for wireless readout of a passively operated humidity sensor circuit is demonstrated. The sensing mechanism of this sensor is related to the polarization in a polyelectrolyte thin film capacitor. This sensor circuit can be manufactured entirely with common printing technologies of today and can be integrated into a low-cost passive sensor label.
33

Underhållsplanering & genomförande på ScandBook

Ferdeen, Erik January 2010 (has links)
Detta projekt gick ut på att utföra ett möjligt underhållsschema för ScandBook i Falun. Innan dess hade akuta reparationer skett då en del lager gått sönder utan föraning på transportlinan. Genom undersökningar som värmekamera, mätklocka, okulärbesiktning m.m. kunde ett beslut fattas om huruvida detta gick att genomföra. Det behövde inte innebära reparationer utan även utbyte av lager, bultar, upphägningar m.m. / <p>A-huset</p>
34

Redesign av gallervält för Svea Redskap AB : Examensarbete, produktutveckling

Pettersson, Oscar January 2008 (has links)
No description available.
35

Performance and performance measurements in complex product development

Johnsson, Stefan January 2008 (has links)
<p>In today’s competitive environment, in which competition increases and the pace of technological change accelerates, the need for deploying product development investments more efficiently and effectively is stronger than ever. The ability to create streams of new successful products to the market is vital for every product delivering company’s survival. Performance measurements are important in order to evaluate the current state of operation of the product development and decide on actions to improve its’ performance. However, in contrast to the concept of productivity in the production process there are no commonly adopted methods for measuring performance within product development. The methodology used in this research is explorative multiple case studies at five companies developing complex products. Complex products in this research involve mechanics, electronics, and software. Moreover, complex products are often long living and most development work is evolutionary in character. An extensive interview study among senior managers and decision makers has been conducted to get a broad and systematic understanding of what performance is and what to measure. The main results developed from this research are two conceptual tools. The first one, the Performance Measurement Evaluation Matrix (PMEX) can be used to evaluate the performance measurement system used at a company. The PMEX makes it possible for managers to get a more holistic view and discuss what the performance measurement system is measuring, and what it is not measuring, in order to decide on what to measure. The second tool, the Product Development Organizational Performance Model (PDOPM) can be used to conceptually analyze performance in the product development process from a holistic system perspective. This is achieved by making efficiency, effectiveness, and uncertainty explicit and by showing how they relate at a strategic, project, and product implementation level. The PMEX and the PDOPM can be used by managers in order to increase the understanding of what performance is and to be able to decide on actions in order to improve the performance of the product development process.</p>
36

Maintenance Program development and the definition of the maintenance program process

Asp, Björn January 2008 (has links)
<p>Under the economical pressure most airlines currently experiences, there is no margin to do too much or not enough of maintenance.</p><p>Customers’ demands high regularity, punctuality and safety. It is all about finding a balance in the maintenance program to be able to control costs and to deliver what the customers expect.</p><p>To actively work with the maintenance program and to continuously evaluate the same is of these reasons utterly important.</p><p>This report considers three methods and defines a process for working with optimization of maintenance intervals.</p><p>The study was carried out at Malmö Aviation, 2006-2007, the purpose was to establish a procedure for working with evaluation of Maintenance Program tasks based on conducted maintenance.</p> / <p>Under den starka ekonomiska press de flesta flygbolag befinner sig idag finns det inte marginaler att utföra för mycket eller för lite underhåll.</p><p>Kunderna kräver hög regularitet, punktlighet och säkerhet. Det gäller att hitta balans i underhållsprogrammet för att kunna kontrollera kostnaderna och leverera det kunderna förväntar sig.</p><p>Att aktivt arbeta med underhållsprogrammet och att kontinuerligt utvärdera detsamma är av dessa anledningar otroligt viktigt.</p><p>Detta arbete tar upp tre arbetssätt och definierar en process för arbete med optimering av underhålls intervall.</p><p>Studien utfördes på Malmö Aviation, 2006-2007, syftet var att ta fram en procedur för utvärdering av underhållsprogrammets uppgifter baserat på utfört underhåll.</p>
37

Produktutveckling av skåpsortiment

Johansson, Andreas, Oskarsson, Petra January 2008 (has links)
<p>Under höstterminen 2007 genomfördes detta examensarbete i samarbete med X ponent Stålinredningar AB (hädanefter kallat X-ponent) i Eskilstuna. Det omfattar 30 högskolepoäng på avancerad nivå inom Produkt- och processutveckling på Mälardalens högskola.</p><p>X-ponent är ett företag som säljer skåp, verktygspaneler och krokar för främst industri och verkstad. Huvudarbetet som utfördes skedde med syfte att förbättra X ponents skåpsortiment. Därtill fanns två sidouppdrag varav det ena handlade om modularisering och det andra om företagets båda skåpserier.</p><p>Arbetet inleddes med en förstudie vars syfte var att få reda på var i sortimentet en arbetsinsats var mest nödvändig. I förstudien samlades X-ponents egen statistik över främst kund- och leverantörsreklamationer in och sammanställdes. X ponents personal och återförsäljare intervjuades också. Vidare analyserades X ponents försäljning och slutligen kartlades konkurrenterna och andra omvärldsfaktorer. Med alla fakta i hand beslutades i samråd med företaget att rikta in det kommande utvecklingsarbetet på en av företagets äldsta och mest säljande skåpprodukter. Ett nytt ersättande skåp skulle tas fram i projektet.</p><p>Därefter analyserades det befintliga skåpet mer ingående genom att användare och tillverkare besöktes. Konkurrerande produkter undersöktes och analyserades också. Det befintliga skåpet led av många problem som har sitt ursprung i den gamla konstruktionen. Många av företagets skåp måste reklameras tillbaka till leverantören på grund av undermålig tillverkning, främst i form av svetsproblem. Det nya skåpet anpassades därmed efter dagens tillverknings¬möjligheter vilket bland annat yttrar sig i att det nästan helt saknar svetsmoment.</p><p>Det visade sig att marknaden verkar föredra skåp utan de karaktäristiska hål som den tidigare produkten har och som används för verktygsupphängning. Därför utvecklades ett skåp utan dessa hål men med möjlighet att montera in lösa verktygspaneler med hål. Skåpet försågs också med andra attribut som främst användare efterfrågat, såsom förhöjningsdel för att underlätta förflyttning med truck samt hål i sidan för anslutning av eldrivna apparater som förvaras i skåpet. Skåpet utrustades även med möjligheten att montera in en jalusidörr.</p><p>Arbetet resulterade också i ett antal rekommendationer till företaget som rör utveckling och försäljning av tillbehör till skåpet. Vidare lämnades rekommendationer kring olika tester som bör göras av det nya skåpet då någon prototyp inte tagits fram under projektets gång. Slutligen lämnades rekommendationer för sidouppdragen modularisering och X-ponents båda skåpserier.</p>
38

Exploring Sustainable Industrial Software System Development : within the Software Architecture Environment

Stoll, Pia January 2009 (has links)
<p>This thesis describes how sustainable development definitions can be transposed to the software architecture environment for the industrial software system domain. In a case study, sustainable development concerns from three companies are investigated for their influence on the dimensions of sustainable development: economical, environmental, and social sustainability. Classifying the case study’s concerns, in the thesis’s Software Engineering taxonomy, shows that the software development concerns are in majority and the software architecture concerns surprisingly few. The economical sustainability concerns dominate followed by social sustainability concerns, including both concerns successfully met and concerns to be met.</p><p>Sustainable industrial software system development is in the thesis defined as: “Sustainable industrial software system development meets current stakeholders’ needs without compromising the software development organization’s ability to meet the needs of future stakeholders”. Understanding current and future stakeholders concerns is necessary for the formulation of sustainability goals and metrics. Clarifying the interrelationships among stakeholders’ concerns’ impact on business goals and software qualities, in the thesis’s Influencing Factors method, proves to help stakeholders understand their future needs.</p><p>Trust is found to be critical for sustainable development. For the establishing of trust between system and system users, the usability quality is vital. To implement usability support in the architecture in the early design phase, reusable architectural responsibilities are created. The reusable architectural responsibilities are integrated into an experience factory and used by the product line system architects, resulting in a return of investment of 25:2.</p> / Pasas- Analyzing the enterprise-, system-, and software architecture impact of stakeholders’ concerns for profitable industrial software systems
39

Projekt KOC-VE : Redesign av lindare för tillverkning av spiraler av motståndstråd

Berggren, Caroline January 2008 (has links)
<p>Denna rapport beskriver processen i ett utvecklingsprojekt av en lindare för tillverkning av</p><p>spiraler av motståndstråd för värmeelement. Projektet var mitt examensarbete för</p><p>högskoleingenjör inom produktdesign och formgivning på Mälardalens Högskola.</p><p>Granlund Tools AB köpte upp den del av Kanthal som tillverkade dessa spiraler och sedan</p><p>lindarens begynnelse på 50-talet har inga större förändringar gjorts. Dessutom har företaget fått</p><p>fortsätta leva med att förknippas med Kanthal mycket på grund av att maskinen fortsatts</p><p>lackerats i den typiska ”Kanthal-blå” färgen.</p><p>Syftet med projektet var att ge deras mest säljande lindare, KOC-VE, ett nytt och modernt</p><p>utseende samt föra in företagets profil i produktens utseende. Viktigt var dock att bibehålla den</p><p>ursprungliga maskinens enkla användargränssnitt eftersom flertalet av företagets kunder</p><p>använder sig av lågutbildad personal.</p><p>Utgångsläget för projektet var de två befintliga maskinerna, KOC-VE och KOC-T. Där KOC-T</p><p>var ett försök till att ta fram en ny och modern lindare, dock ser den trots sina förbättrade</p><p>funktioner gammalmodig ut samt att den på grund av sin PLC är för avancerad för flertalet av</p><p>företagets kunder.</p><p>Tillsammans med företaget togs ett antal koncept fram som sedan utvärderades och slutligen</p><p>utvecklades till slutresultatet. De metoder som användes var vanlig traditionell brainstorming</p><p>och handskisser. En enklare CAD-modell gjordes på det slutliga förslaget för godkännande och</p><p>vidare utvecklingsarbete för att till sist resultera i en mer detaljerad CAD-modell och en</p><p>enklare fysisk modell.</p><p>Resultatet var inte bara omtyckt av företaget av utseendemässiga skäl utan även för de flertalet</p><p>förbättringar som gjordes med konstruktionen och byte av vissa komponenter som exempelvis</p><p>växellådan, luftsaxen och bromsen. Konceptet ansågs även vara realistiskt gällande montering,</p><p>tillverkningsmetod, material och kostnader. De ökade kostnaderna för redesign väntas jämna ut</p><p>sig med de besparingar som görs i och med de nya konstruktionsmässiga lösningarna. De</p><p>väntas även kunna täckas med ett högre pris som en följd av den höjda kvalitén och den ökade</p><p>upplevda kundnyttan.</p>
40

Airport Logistics : Modeling and Optimizing the Turn-Around Process

Norin, Anna January 2008 (has links)
<p>The focus of this licentiate thesis is air transportation and especially the logistics at an airport. The concept of airport logistics is investigated based on the following definition: <em>Airport logistics is the planning and control of all resources and information that create a value for the customers utilizing the airport</em>. As a part of the investigation, indicators for airport performance are considered.</p><p>One of the most complex airport processes is the turn-around process. The turn-around is the collective name for all those activities that affect an aircraft while it is on the ground. In the turn-around process almost all of the actors operating at the airport are involved and the process is connected to other activities which take place on airside, in the terminal as well as in the control tower. This makes the turn-around process an excellent focal point for studying airport logistics.</p><p>A detailed conceptual model of the turn-around process is developed and a simplified version of this is implemented in a computerized simulation program. The aim of the simulation is to enable the assessment of various logistical operations involved in turn-around, and their impact on airport performance. The flow of support vehicles serving the aircraft with fuel, food, water etc during the turn-around is received particular attention. The output from the model can be used as indicators for the airport performance.</p><p>One of the most interesting support flows to study is the flow of de-icing trucks. De-icing is performed to remove ice and snow from the aircraft body and to prevent the build up of new ice. There is a limited time span prior the take off, within which de-icing has to be performed. This makes the time of service critical. An optimization approach is developed to plan a schedule for the de-icing trucks. Scheduling the flow of de-icing trucks can be seen as a heterogeneous vehicle routing problem with time windows. The objective of the optimization is total airport performance and a heuristic method is used to solve the problem.</p><p>The optimized schedule for the de-icing trucks is used as input in the simulation model. The schedule optimized for the entire airport is compared to a schedule based on a simpler scheduling rule as well as a schedule optimized for the de-icing company. By running the model with the different routings, it is found that the schedule optimized for the entire airport gives the best results according to the indicators specified for measuring airport performance.</p>

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