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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

Prototype Extraction and Learning Using Prototypes in an Artificial Neural Network

Linåker, Fredrik January 1997 (has links)
<p>A prototype is a general description which depicts what an entire set of exemplars, belonging to a certain category, looks like. We investigate how prototypes, in the form of mathematical averages of a category's exemplar vectors, can be represented, extracted, accessed, and used for learning in an Artificial Neural Network (ANN). From the method by which an ANN classifies exemplars into categories, we conclude that prototype access (the production of an extracted prototype) can be performed using a very simple architecture. We go on to show how the architecture can be used for prototype extraction by simply exploiting how the back-propagation learning rule handles one-to-many mappings. We note that no extensions to the classification training sets are needed as long as they conform to certain restrictions. We then go on to show how the extracted prototypes can be used for the learning of new categories which are compositions of existing categories and we show how this can lead to reduced training sets and ultimately reduced learning times. A number of restrictions are noted which have to be considered in order for this to work. For example, the exemplar representations must be systematic and the categories linearly separable. The results, and other properties of our network, are compared with other architectures which also use some kind of prototype concept. Our conclusion is that prototype extraction and learning using prototypes is possible using a simple ANN architecture. Finally, we relate our system to the symbol grounding problem and point out some directions for future work.</p>
62

A Conflict Detection and Resolution Mechanism for Bounded-Delay Replication

Lundström, Johan January 1997 (has links)
<p>One way of avoiding unpredictable delays, in a distributed real-time database, is to allow transactions to commit locally. In a system supporting local commit, and delayed propagation of updates, the replication protocol must be based on eventual consistency. In this thesis, we present a bounded-delay replication method which is based on eventual consistency. The approach used is to divide the replication protocol into three different problems; propagation, conflict detection and conflict resolution, where we focus on the conflict detection and resolution mechanism. We have evaluated different eventual consistency protocols and chosen version vectors as the base for the conflict detection algorithm. We introduce a method of separating policy and mechanism in the conflict resolution mechanism, which is based on forward recovery to avoid unnecessary computation. The protocols presented in this work are aimed to be used in the distributed active real-time database system DeeDS. We conclude that the protocol proposed can be used in DeeDS, under the assumption that no partition failures occur.</p>
63

Extending CDIF to support Business Rules targeting SQL3

Palmquist, Kristian January 1997 (has links)
<p>Business Rules have gained attention in recent years and are now considered to be important organizational elements. Several sources in the literature argue that there are major achievements to be made with an explicit business rule focus in software engineering, e.g. promoting communication between analysts and users and accounting for changeability and maintenance aspects. However, to fully take advantage of an explicit rule focus in software engineering requires the ability to create business rule models. The problem is that business rule models of realistic size quickly become extensive and complex, hence there is a need for CASE tool support.</p><p>We choose a modeling technique from the literature which is suited to express business rules. Basec on this modeling technique we propose an extension to the Case Data Interchange Format standard (CDIF), thereby allowing the standard to express and support the transfer of business rule models. In addition, we define a mapping procedure that which maps business rules from the conceptual modeling level via CDIF (using the proposed extensions) to SQL3 triggers. The main idea is that the mapping algorithms could be used by a CDIF conformant CASE tool which allows traditional database design, together with extended modeling constructs for expressign business rules.</p>
64

Överföring av program från värddator till målmiljö

Bergfeldt, Niklas January 1999 (has links)
<p>Detta arbete tar upp olika överföringstekniker för att uppdatera ett program på en målmiljö. De tre överföringstekniker som analyseras är moduluppdelning, patchning och komprimering. En litteraturstudie har genomförts för att ta fram för- och nackdelar med de olika teknikerna och för att beskriva hur de fungerar. En praktisk applicering av överföringsteknikerna har även gjorts på ett specifikt PLC-system för att se vad dessa kan göra för uppdateringstiden i denna miljö. Resultatet av arbetet visade att moduluppdelning är att föredra i de fall där uppdelning av programmet är möjlig. Patchning är däremot mest lämpad då varje uppdatering av programmet är mycket liten och det således inte skiljer mycket mellan de olika versionerna av programmet. Komprimering är att föredra då det ofta är frågan om stora modifieringar i programmet eftersom komprimering ger en näst intill konstant vinst sett ur procentuell synvinkel, även om denna vinst endast är runt 50%.</p>
65

Kravspecifikationens innehåll och struktur : en jämförelse med byggbranschens kontraktshandlingar

Lindholm, Christer January 2000 (has links)
<p>Dynamiken i det moderna samhället gör att förutsättningarna för företag och organisationer ständigt förändras. Informationssystemen blir då väldigt viktiga för att företagen skall få rätt information i rätt tid. Även informationssystemen måste ibland förändras och kraven på ett nytt informationssystem anges i en kravspecifikation. Denna kravspecifikation upprättas i den del av systemutvecklingsarbetet som kallas för requirements engineering (RE).</p><p>Denna rapport är ett examensarbete inom det systemvetenskapliga programmet vid Högskolan i Skövde. Författaren har tidigare arbetat som byggnadsingenjör i flera år och gör i detta arbete en jämförelse mellan byggbranschens kontraktshandlingar och systemutvecklingsområdets kravspecifikation. Syftet med jämförelsen är att utreda om systemutvecklingsområdet har något att lära av byggbranschen när det gäller strukturering och utformning av kravdokumentationen.</p><p>Undersökningen har utförts som en litteraturstudie, där tre olika utvecklingsmetoder har studerats. Undersökningen visar att byggbranschens kontraktshandlingar har en bättre struktur och ett mer omfattande innehåll än de tre studerade förslagen till kravspecifikation.</p>
66

Methods for Increasing Software Testability

Lindström, Birgitta January 2000 (has links)
<p>We present a survey over current methods for improving software testability. It is a well-known fact that the cost for testing of software takes 50\% or more of the development costs. Hence, methods to improve testability, i.e. reduce the effort required for testing, have a potential to decrease the development costs. The test effort needed to reach a level of sufficient confidence for the system is dependent on the number of possible test cases, i.e., the number of possible combinations of system state and event sequences. Each such combination results in an execution order. Properties of the execution environment that affect the number of possible execution orders can therefore also affect testability. Which execution orders that are possible and not are dependent of processor scheduling and concurrency control policies. Current methods for improving testability are investigated and their properties with respect to processor scheduling and concurrency control analyzed. Especially, their impact on the number of possible test cases is discussed. The survey revealed that (i) there are few methods which explicitly address testability, and (ii) methods that concern the execution environment suggest a time-triggered design. It is previously shown that the effort to test an event-triggered real-time system is inherently higher than testing a time-triggered real-time system. Due to the dynamic nature of the event-triggered system the number of possible execution orders is high. A time-triggered design is, however, not always suitable. The survey reveals an open research area for methods concerning improvement of testability in event-triggered systems. Moreover, a survey and analysis of processor scheduling and concurrency control properties and their effect on testability is presented. Methods are classified into different categories that are shown to separate software into different levels of testability. These categories can form a basis of taxonomy for testability. Such taxonomy has a potential to be used by system designers and enable them to perform informed trade-off decisions.</p>
67

Dataorienterade komponenter för Adobe Flash

Frennevi, Anton January 2007 (has links)
No description available.
68

Distribution of expected utility in second-order decision analysis

Sundgren, David January 2007 (has links)
<p>In explicatione consiliorum, maxima facere communis utilitas saepe trita ratio deligendi meliorem optionem est. Verum si probabilitates et utilitates incertae vel dubiae sint, communis utilitas perturbationes affert. Studium secundi ordinis effectuum in explicatione consiliorum explanat momentum structurae quaestionium consilii, insidias aliquas ad consilium capiendum indicat et facilem ad efficiendum et intellegendum rationem comparandi varia consilia suadet. Haec thesis tractat de secundi ordinis effectibus explicationis consilii, praesertim de commune utilitate et de probabilitatibus coniunctis intervallo. Voces apertae distributionum ordinis secundi in probabilitatibus intervallo conjunctis insitarum omnino et item distributionum utilitatis expectatae in parvis quaestionibus consiliorum eduntur. His distributionibus cognitis studetur res inflexionis, aliter dictu intentio fidei.</p> / <p>In decision analysis maximising the expected utility is an often used approach in choosing the optimal alternative. But when probabilities and utilities are vague or imprecise expected utility is fraught with complications. Studying second-order effects on decision analysis casts light on the importance of the structure of decision problems, pointing out some pitfalls in decision making and suggesting an easy to implement and easy to understand method of comparing decision alternatives. The topic of this thesis is such second-order effects of decision analysis, particularly with regards to expected utility and interval-bound probabilities. Explicit expressions for the second-order distributions inherent in interval-bound probabilities in general and likewise for distributions of expected utility for small decision problems are produced. By investigating these distributions the phenomenon of warping, that is concentration of belief, is studied.</p>
69

On Aircraft Conceptual Design : A Framework for Knowledge Based Engineering and Design Optimization

Amadori, Kristian January 2008 (has links)
<p>This thesis presents a design framework where analytical tools are linked together and operated from an efficient system level interface. The application field is aircraft conceptual design. Particular attention has been paid to CAD system integration and design optimization.</p><p>Aircraft design is an inherently multidisciplinary process. The goal is to search for the design that, in the best of possible ways, fulfills the requirements. It is therefore desirable to be able to effectively investigate and analyze solutions from a variety of points of view, weighting together the results and gathering a general figure of merit. At the same time, increasing competition on a global market forces to shorten the design process and to reduce costs. Thus a system that allows a tight and efficient integration of different disciplines and improving data flow and storage plays a key role.</p><p>Integrating a CAD system to the framework is of central relevance. The geometrical model includes most of the information; specific data, required to carry out particular analysis, can be extracted from it. This is possible adopting parametric associative models that are controlled from a spreadsheet user interface. Strategies for building CAD models with a very high degree of flexibility are presented. Not only the external shape can be changed, but also the internal structure can be completely modified. Structural elements can be added or removed, and their position and shaping changed.</p><p>In this work the design of an Unmanned Aerial Vehicle is used as test case for comparing three different optimization algorithms. The presented framework is also used for automatically design Micro Aerial Vehicles, starting from a short list of requirements and ending with a physical prototype produced by a rapid prototyping machine.</p>
70

The Apparent Arbitrariness of Second-Order Probability Distributions

Sundgren, David January 2011 (has links)
Adequate representation of imprecise probabilities is a crucial and non-trivial problem in decision analysis. Second-order probability distributions is the model for imprecise probabilities whose merits are discussed in this thesis. That imprecise probabilities may be represented by second-order probability distributions is well known but there has been little attention to specific distributions. Since different probability distributions have different properties, the study of the desired properties of models of imprecise probabilities with respect to second-order models require analysis of particular second-order distributions. An often held objection to second-order probabilities is the apparent arbitrariness in the choice of distribution. We find some evidence that the structure of second-order distributions is an important factor that prohibits arbitrary choice of distributions. In particular, the properties of two second-order distributions are investigated; the uniform joint distribution and a variant of the Dirichlet distribution that has the property of being the normalised product of its own marginal distributions. The joint uniform distribution is in this thesis shown to have marginal distributions that belie the supposed non-informativeness of a uniform distribution. On the other hand, the modified Dirichlet distribution discovered here has its information content evenly divided among the joint and marginal distributions in that the total correlation of the variables is minimal. It is also argued in the thesis that discrete distributions, as opposed to the continuous distributions mentioned above, would have the advantage of providing a natural setting for updating of lower bounds, and computation of expected utility is made more efficient. / In placitorum scrutatione maxima et mehercle minime levis difficultas eo spectat, quomodo probabilitates dubiae bene ostendantur. In hac thesi de utilitate distributionum probabilitatum secundi ordinis disseremus, in quantum ad probabilitates dubias ostendendas valeant. Omnibus fere notum est probabilitates dubias ostendi posse per distributiones probabilitatum secundi ordinis, sed pauci operam distributionibus singulis operam contulerunt. Cum tamen distributiones probabilitatum valde inter se diversae sint, si quis proprietatibus desideratis probabilitatum dubiarum secundi ordinis studium conferre vult, primum debet quasdam praescriptas distributiones secundi ordinis investigare. Sed fortasse, quod saepenumero fieri solet, quispiam dixerit probabilitates secundi ordinis nulla, ut videtur, ratione habita quasi vagari quoad delectum distributionis. Nos tamen nonnulla indicia comperimus quibus freti confirmare audemus ipsam formam distributionum secundi ordinis multum valere ad praedictum distributionum secundi ordinis delectum rationabiliter peragendum. Imprimis proprietates duarum distributionum secundi ordinis investigabimus, nimirum distributionis uniformis coniunctae et alterius cuiusdam speciei distributionis quae ‘Dirichleti’ vocatur, quae ex ipsius distributionibus marginalibus ad normam correcta oritur. In hac thesi probamus illam coniunctam uniformem distributionem continere distributiones marginales eius modi quae illos refellant qui negant distributionem uniformem quicquam alicuius momenti afferre. Attamen in illa distributione Dirichleti paulo mutata, quam hoc loco patefacimus, omnia aequaliter inter coniunctas et marginales distributiones divisa sunt, in quantum tota ratio quae inter variantia intercessit ad minimum reducitur. Insuper in hac thesi confirmamus distributiones discretas potius quam antedictas distributiones continuas in hoc utiliores esse, quod per eas limites inferiores in melius mutare licet, et beneficia exspectata accuratius computari possunt. / Adekvat representation av osäkra eller imprecisa sannolikheter är ett avgörande och icke-trivialt problem i beslutsanalys. I denna avhandling diskuteras förtjänsterna hos andra ordningens sannolikheter som en modell för imprecisa sannolikeheter. Att imprecisa sannolikheter kan representeras med andra ordningens sannolikheter är välkänt, men hittills har särskilda andra ordningens föredelningar inte ägnats någon större uppmärksamhet. Då olika sannolikhetsfördelningar har olika egenskaper kräver studiet av önskvärda egenskaper hos modeller för imprecisa sannolikheter en granskning av specifika andra ordningens fördelningar. Den godtycklighet som tycks vidhäfta valet av andra ordningens fördelning är en ofta förekommande invändning mot andra ordingens sannolikhetsfördelningar. Vi finner vissa belägg för at strukturen hos andra ordningens fördelningar är en omständighet som hindrar godtyckligt val av fördelningar. I synnerhet undersöks egenskaper hos två andra ordningens fördelningar; den likformiga simultana fördelningen och en variant av Dirichletfördelningen med egenskapen att vara lika med den normaliserade produkten av sina egna marginalfördelningar. Den likformiga simultana fördelningen visas i avhandligen ha marginalfördelningar som motsäger den förmodat icke-informativa strukturen hos en likformig fördelning. Å andra sidan gäller för den modifierade Dirichletfördelningen som upptäckts här att informationsinnehållet är jämnt fördelat mellan den simultana fördelningen och marginalfördelningarna; den totala korrelationen mellan variablerna är minimal. Det hävdas också i avhandlingen att diskreta sannolikhetsfördelningar i motsats till de kontinuerliga fördelningar som nämnts ovan har fördelen att utgöra en naturlig miljö för uppdatering av undre gränser och dessutom tillåta en mer effektiv beräkning av förväntad nytta.

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