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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.
1

Simulation based exploration of a loading strategy for a LHD-vehicle / Simuleringsbaserad utforskning av styrstrategier för frontlastare

Lindmark, Daniel January 2016 (has links)
Optimizing the loading process of a front loader vehicle is a challenging task. The design space is large and depends on the design of the vehicle, the strategy of the loading process, the nature of the material to load etcetera. Finding an optimal loading strategy, with respect to production and damage on equipment would greatly improve the production and environmental impacts in mining and construction. In this thesis, a method for exploring the design space of a loading strategy is presented. The loading strategy depends on four design variables that controls the shape of the trajectory relative to the shape of the pile. The responses investigated is the production, vehicle damage and work interruptions due to rock spill. Using multi-body dynamic simulations many different strategies can be tested with little cost. The result of these simulations are then used to build surrogate models of the original unknown function. The surrogate models are used to visualize and explore the design space and construct Pareto fronts for the competing responses. The surrogate models were able to predict the production function from the simulations well. The damage and rock spill surrogate models was moderately good in predicting the simulations but still good enough to explore how the design variables affect the response. The produced Pareto fronts makes it easy for the decision maker to compare sets of design variables and choose an optimal design for the loading strategy.
2

Tailored Preloading, Precaching and Prefetching Loading Strategies for Applications Through a Multi-Component AI

Öfver, Martin January 2022 (has links)
When using a personal computer the user could experience starting an application for the first time, loading a level in a video game or any tedious arbitrary loading process. These loading processes often load mostly the same data each time and consume time where the user is waiting. Making it faster is often preferred. The file-caching tactics Preloading, Precaching and Prefetching (PPP) have received past research, mostly to make generic improvements or better algorithms. The gap in the work is a lack of non-generic file-caching optimisation algorithms. To improve loading times during a Mostly Deterministic File-Loading Process (MDFLP), this research suggests a Multi-Component Artificial Intelligence (MCAI) that analyses the application's runtime results. The proposed MCAI would not be a one size fits all kind of solution but rather generate a tailored File-Loading Strategy (FLS) for the application. The aim of the research is to investigate if a MCAI could improve loading speeds of arbitrary application's MDFLPs. The objectives are to implement a test synthesiser for generating synthetic test environments to use MCAI on, to implement the MCAI and perform the experiments. The research questions regard how the MCAI can analyse inefficient operations during a MDFLP, propose measures that increase efficiency and aid developers independently of the high-level technology used. They also regard how the MCAI through iterative runs of an application can generate an application-specific FLS which is better in terms of PPP performance. The method section goes into detail about how the test synthesiser, the MCAI and the host application is implemented. It also explains how the experiment was made, what the experiment tested, what data was collected and what hardware and software were used. The result first shows in detail how the MCAI works on a simple test and then moves on to three extensive tests. Two of the tests show positive results, where the MCAI manages to generate an optimal FLS, whilst the MCAI fails in the third test. The third test highlights inherent weaknesses in the MCAI. The conclusion is that the MCAI shows potential. In its weakest form, it still manages to produce good results, where the MCAI generates a FLS that improves the load time performance. There is improvement potential for the MCAI to make it more smart, efficient, reliable and make it able to generate a FLS for test three. The research leaves room for follows ups and projects, like developing the MCAI further and performing case studies. / När en dator används kan användaren uppleva starten av en applikation för första gången, inladdningen av en nivå i ett TV-spel eller någon tråkig, godtycklig inladdningsprocess. Dessa laddningsprocesser laddar ofta mestadels samma data varje gång och förbrukar tid där användaren väntar. Att göra det snabbare är ofta att föredra. Det har tidigare forskats om filcachningstaktikerna Preloading, Precaching och Prefetching (PPP), mest för att göra generiska förbättringar eller bättre algoritmer. Klyftan i forskningen är bristen på icke-generiska filcachande-optimeringsalgoritmer. För att förbättra laddningstiderna under en övervägande deterministisk filladdningsprocess (MDFLP), föreslår denna forskning en Multi-Komponents Artificiell Intelligens (MCAI) som analyserar programmets körtidsresultat. Den föreslagna MCAIn skulle generera en skräddarsydd filladdningsstrategi (FLS) för applikationen. Syftet med forskningen är att upptäcka om en MCAI kan förbättra laddningshastigheterna för godtyckliga applikationers MDFLP:er. Målen är att implementera en testsyntetiserare för att generera syntetiska testmiljöer att använda MCAI på, att implementera MCAI och utföra experimenten. Forskningsfrågorna handlar om hur MCAI kan analysera ineffektiva operationer under en MDFLP, föreslå åtgärder som ökar effektiviteten och hjälper utvecklare oberoende av vilken högnivåteknik som används. Det handlar också om hur MCAI genom körningar av en applikation kan generera en FLS som är bättre i PPP-prestanda. Metodavsnittet går in i detalj om hur testsyntesen, MCAI och värdapplikationen implementeras. Den förklarar också hur experimentet gjordes, vad experimentet testade, vilken data som samlades in och vilken hårdvara och mjukvara som användes. Resultatet visar först i detalj hur MCAI fungerar på ett enkelt test och går sedan vidare till tre omfattande tester. Två av testerna visar positiva resultat, där MCAI lyckas generera en optimal FLS, medan MCAI misslyckas helt i det tredje testet. Det tredje testet belyser inneboende svagheter i MCAI. Slutsatsen är att MCAI visar potential. Det finns förbättringspotential för MCAI för att göra den mer smart, effektiv, pålitlig och lyckas generera en bra FLS för test tre. Forskningen lämnar utrymme för uppföljningar och projekt, som att vidareutveckla MCAI och utföra fallstudier.

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