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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.
11

Development and Evaluation of Multiple Objects Collision Mitigation by Braking Algorithms / Utveckling och utvärdering av CMbB-algoritmer för multipla objekt

Kivrikis, Andreas, Tjernström, Johan January 2004 (has links)
<p>A CMbB system is a system that with the help of sensors in the front of a car detects when a collision in unavoidable. When a situation like that is detected, the brakes are activated. The decision of whether to activate the brakes or not is taken by a piece of software called a decision maker. This software continuously checks for routes that would avoid an object in front of the car and as long as a path is found nothing is done. Volvo has been investigating several different CMbB-systems, and the research done by Volvo has previously focused on decision makers that only consider one object in front of the car. By instead taking all present objects in consideration, it should be possible to detect an imminent collision earlier. Volvo has developed some prototypes but needed help evaluating their performance. </p><p>As part of this thesis a testing method was developed. The idea was to test as many cases as possible but as the objects’ possible states increase, the number of test cases quickly becomes huge. Different ways of removing irrelevant test cases were developed and when these ideas were realized in a test bench, it showed that about 98 % of the test cases could be removed. </p><p>The test results showed that there is clearly an advantage to consider many objects if the cost of increased complexity in the decision maker is not too big. However, the risk of false alarms is high with the current decision makers and several possible improvements have therefore been suggested.</p>
12

A Synthesizable VHDL Behavioral Model of A DSP On Chip Emulation Unit

Li, Qingsen January 2003 (has links)
This thesis describes the VHDL behavioral model design of a DSP On Chip Emulation Unit. The prototype of this design is the OnCE port of the Motorola DSP56002. Capabilities of this On Chip Emulation Unit are accessible through four pins, which allows the user to step through a program, to set the breakpoint that stop program execution at a specific address, and to examine the contents of registers, memory, and pipeline information. The detailed design that includes input/output signals and sub blocks is presented in this thesis. The user will interact with the DSP through a GUI on the host computer via the RS232 port. An interface between the RS232 and On Chip Emulation Unit is therefore designed as well. The functionality is designed to be same as described by Motorola and it is verified by a test bench. The writing of the test bench, test sequence and results is presented also.
13

Development and Evaluation of Multiple Objects Collision Mitigation by Braking Algorithms / Utveckling och utvärdering av CMbB-algoritmer för multipla objekt

Kivrikis, Andreas, Tjernström, Johan January 2004 (has links)
A CMbB system is a system that with the help of sensors in the front of a car detects when a collision in unavoidable. When a situation like that is detected, the brakes are activated. The decision of whether to activate the brakes or not is taken by a piece of software called a decision maker. This software continuously checks for routes that would avoid an object in front of the car and as long as a path is found nothing is done. Volvo has been investigating several different CMbB-systems, and the research done by Volvo has previously focused on decision makers that only consider one object in front of the car. By instead taking all present objects in consideration, it should be possible to detect an imminent collision earlier. Volvo has developed some prototypes but needed help evaluating their performance. As part of this thesis a testing method was developed. The idea was to test as many cases as possible but as the objects’ possible states increase, the number of test cases quickly becomes huge. Different ways of removing irrelevant test cases were developed and when these ideas were realized in a test bench, it showed that about 98 % of the test cases could be removed. The test results showed that there is clearly an advantage to consider many objects if the cost of increased complexity in the decision maker is not too big. However, the risk of false alarms is high with the current decision makers and several possible improvements have therefore been suggested.
14

Wet clutch load modeling for powershift transmission bench tests. / Belastningsmodellering av våta kopplingar i riggprov av powershift-transmission.

Gustafsson, Filip January 2014 (has links)
In this thesis a model is developed for calculating the loads on the wetclutches in apowershift transmission. This thesis was done at Volvo CE in Eskilstuna and is focusedon their 4-speed countershaft transmissions. The goal of the project is to be able tocalculate the loads automatically during the transmission tests and thus acquire increasedknowledge about what occurs during operation.The model was developed by first generating a number of concepts and then evalu-ating them to decide which one should be developed further. The chosen concept wasthen developed further and implemented into the test equipment as a calculation script.The chosen loads to model were the energy absorbed in each clutch, the coefficient offriction (COF) and the slip distance. The COF was later found to give too unreliableresults to be used in any other way than as a benchmark for how well the model wasconfigured and to see any large changes in COF.The model was validated by calculating the energy absorbed in a HTE-200 seriestransmission and comparing it to a reference calculation model. It was seen that theresults from the new model are very close to the reference result. The energy lostcalculated by the new model will be equal to 94 % of the energy lost calculated by thereference model, but only when measuring the inertia phase. The energy lost is equalto 135 % when the torque phase is included. The increasing difference is believed tobe because of an error in the reference model that means it does not cover the torquephase.
15

Etude expérimentale et développement numérique d'une modélisation des phénomènes physicochimiques dans un propulseur hybride spatial / Experimental study and numerical development of physical-chemical phenomena model in a hybrid rocket motor

Mangeot, Alexandre 19 December 2012 (has links)
La propulsion hybride utilise classiquement un comburant liquide (ou gazeux) injecté dans une chambre de combustion qui contient le carburant à l'état solide. La flamme de diffusion, qui apparait à la rencontre des deux flux de matière, est autoentretenue par la pyrolyse du carburant consécutive à l’apport de chaleur produite par la combustion. Afin d'améliorer les performances de ce type de propulsion, il est nécessaire de bien comprendre le couplage physicochimique des phénomènes. Le couple d'ergols polyéthylène/mélange gazeux dioxygène et diazote a été choisi pour cette étude. Les caractéristiques du polyéthylène ont été déterminées par des analyses physicochimiques, elles permettent de mettre en évidence un effet de la pression et de la nature de l'atmosphère sur la composition des produits de pyrolyse. Un banc d'essais de combustion avec une instrumentation a permis de caractériser le comportement du polyéthylène en situation réelle. Les données acquises ont été analysées afin d'obtenir des grandeurs physiques pertinentes à comparer avec des résultats de simulations. Pour effectuer des simulations de chambre de combustion de propulseur hybride, le développement d'un modèle numérique instationnaire et bidimensionnel a débuté. De nombreux cas test "académiques" sont présentés et ont confirmés la bonne implémentation des méthodes numériques de résolution et des équations physiques et chimiques. Cependant, lors des simulations de la chambre de combustion complète, une divergence de pression est apparue dont les causes ont été activement recherchées. / The hybrid space propulsion classically employs a liquid (or gaseous) oxidizer injected into the combustion chamber which contains the solid reducer. The diffusion flame, which appears at the confluence of the oxidizer and reducer mater fluxes, is auto-entertained by the fuel pyrolysis piloted by the heat which is provided to it by the combustion. In order to increase performances of this propulsion system, it is necessary to well understand the coupling effect of the physical and chemical phenomena. The propellants couple polyethylene/gaseous oxygen and nitrogen mixture has been chosen for this study. Properties of the polyethylene have been determined by several chemical analyses, showing that there are a pressure and atmosphere nature effects on the pyrolysis chemical composition. A test bench with instrumentation allowed to characterize the behavior of the polyethylene in real situation. Data acquired have been analyzed in order to obtain physical variables relevant for comparing the numerical simulations results. To undertake simulation of the combustion chamber of hybrid rocket, a new numerical model has been developed. Numerous "academic" test cases are presented and confirmed a good implementation of the numerical method and of the physical and chemical models. Nevertheless, during simulations of hybrid combustion chamber, a pressure divergence has appeared thus causes have been actively investigated.
16

Návrh zkušebního zařízení nové generace pro dlouhodobé zkoušky univerzálního aktuátoru

STREJC, Jakub January 2017 (has links)
Actuators are a fundamental part of many modern devices and machines nowadays. Typically, they are responsible for operation of various machine parts, for instance correct performance of flaps and valves. Since actuators are an important device, it is crucial and beneficial to pursue development and testing of this component. This Master's thesis focusses on the selection and construction of a test bench used for long-term tests of a universal actuator (General Purpose Actuator), widely used in automobile industry. The main reason for assigning this practical task is the unsatisfactory current type of the test bench, which does not comply with the modern testing demands of the requesting company.
17

PROJETO, IMPLEMENTAÇÃO E AUTOMAÇÃO DE UMA BANCADA PARA ENSAIOS DE MOTORES A RELUTÂNCIA CHAVEADOS / PROJECT, IMPLEMENTATION AND AUTOMATION OF A BENCH FOR TESTING SWITCHED RELUCTANCE MOTORS

TEIXEIRA, Weldon Carlos Elias 30 June 2009 (has links)
Made available in DSpace on 2014-07-29T15:08:20Z (GMT). No. of bitstreams: 1 anexo dissertacao weldon.pdf: 502529 bytes, checksum: e010c8b9335a273bd3a0c2fd72779737 (MD5) Previous issue date: 2009-06-30 / This work presents a proposal for testing Switched Reluctance Motors, which is feasible by the design and construction of an automated test bench. The test proposal intends to measure phase s resistance; to compute copper loss; to obtain the magnetizing curves for aligned and unaligned rotor and a performance test, which is based on fixing the under test motor rotor speed by a drive machine that is drove by a frequency inverter. The computational automation is restricted in changing the d.c. voltage applied to the under test switched reluctance motor by a programmable sinusoidal voltage source; changing and/or fixing the under test rotation speed of the switched reluctance; changing the semiconductor-switch switching angle; acquisition and processing of the data obtained in the tests. Computational simulations were performed for validating tests results made in an available switched reluctance motor / Este trabalho apresenta uma proposta de ensaios de Motores a Relutância Chaveados, a qual se viabiliza através do projeto e construção de uma bancada automatizada. A proposta de ensaios compreende, entre outros procedimentos, em medir as resistências das fases; calcular a perda ôhmica; determinação das curvas de magnetização nas posições de pólos, do estator e rotor, alinhados e desalinhados e o desempenho, o qual se fundamenta na fixação da velocidade de rotação dos motores sob teste através de uma máquina de indução trifásica de grande potência comparada à potência do motor sob teste, cujo acionamento é realizado por meio de um conversor de freqüência. A automação realizada via computacional está circunscrita aos seguintes aspectos: variação da tensão de corrente contínua aplicada ao motor a relutância; variação e fixação da velocidade de ensaio do motor a relutância; variação do ângulo de disparo das chaves semicondutoras do conversor de potência; aquisição e processamento dos dados obtidos nos ensaios e determinação da velocidade do motor. Através do método dos elementos finitos foram realizadas simulações computacionais pertinentes para confrontar com os ensaios realizados em um motor a relutância chaveado disponível.
18

Modelling of Test Bench for Road Load Simulation

Åberg Skender, Dennis January 2017 (has links)
Warehouse forklifts are often powered by batteries. By using a test bench where the forklift can be driven in a certain driving-cycle, the battery capacity can be tested. To obtain the same speed curve on the test bench as a forklift obtains when driving on a real road, the test bench must be able to simulate road load. In this master’s thesis, a test bench is modelled in Simulink using grey-box modelling and validated with measured data. Also, a speed regulator is developed and implemented in the test bench model to simulate road load. Simulations with the model and the speed regulator show high accuracy when compared against measured data. However, the results show that the pre-attached torque sensor is not optimally located, and that the gear oil temperature is of interest to measure to be able to model the friction torque as a function of the temperature. / Lagertruckar drivs ofta av batterier. Batterikapaciteten kan testas genom att använda en testbänk där trucken körs i en körcykel. För att simulera samma hastighetskurva på testbänken som trucken erhåller vid riktig körning på väg måste testbänken kunna simulera vägmotstånd. I detta examensarbete modelleras en testbänk i Simulink genom grey-box modellering och valideras med uppmätt data. Även en hastighetsregulator utvecklas och implementeras i modellen för att simulera vägmotstånd. Simuleringar med modellen och hastighetsregulatorn visar på hög träffsäkerhet jämfört med uppmätt data. Resultaten visar dock på att den monterade momentsensorn inte är optimalt belägen och att växeloljans temperatur är av intresse att mäta för att kunna modellera friktionen som en funktion av temperaturen.
19

Approche passive pour la modélisation, la simulation et l'étude d'un banc de test robotisé pour les instruments de type cuivre / Passive approach for the modelling, the simulation and the study of a robotised test bench for brass instruments

Lopes, Nicolas 15 June 2016 (has links)
Cette thèse s'inscrit dans le contexte de la robotique, de l'automatique et de l'acoustique musicale. Elle propose une étude d'un banc de test robotisé pour le jeu des cuivres et se décompose selon trois volets: la modélisation passive du système, sa simulation et son développement. La modélisation utilise le formalisme passif des systèmes hamiltoniens à ports. Les principaux éléments du système sont: l'alimentation en air pour le souffle, l'excitateur (composé de deux lèvres et d'un jet d'air) et un résonateur acoustique. Un nouveau modèle de jet d'air généré entre les lèvres est proposé. Ce modèle a pour but de restituer un bilan de puissance plus proche de la réalité physique que les modèles couramment utilisés. Pour la simulation à passivité garantie, la méthode du gradient discret est présentée. Elle ne garantit pas l'existence et l'unicité d'une solution et est limitée au second ordre de consistance numérique. De plus, son exécution nécessite des algorithmes d'optimisations non linéaires. Pour pallier ces limitations, une méthode à plusieurs étapes de type Runge-Kutta double et basée sur un changement de variable est proposée. Des résultats de simulations sont interprétés et comparés à ceux issus d'un modèle classique de la littérature. Le banc de test, ainsi que les développements techniques sont présentés. Ils permettent la mise au point d'expériences de cartographies répétables pouvant être utilisées pour caractériser différents instruments de musique. Enfin, des résultats numériques et expérimentaux sont comparés afin de mettre en avant les défauts et les qualités du modèle proposé. / This thesis is to be seen against the robotic, the automatic, and the musical acoustic backgrounds. It provides a study of a robotized test bench for brass instruments and is divided into three parts: the passive modelling of the system, its simulation and its development. The modelling uses a passive formalism, namely, the ports-Hamiltonian systems. The main parts of the complete system are: an air supply for the breath, an acoustic exciter (composed of a couple of artificial lip and an air jet) and an acoustic resonator. A new model for the air jet generated between the lips is proposed. This model aims at providing a power balance, which is closer to the real system than other commonly used models. The discrete gradient method is presented to perform passive simulations. It does not generally guaranty the existence and uniqueness of a solution and is limited to the second order of numerical consistency. Moreover, its execution needs nonlinear optimisation algorithms. To compensate for these limitations, a multi-stage method of double Runge-Kutta type and based on a change of variable is proposed. Results from simulations are interpreted and compared to those coming from a Bernoulli type model. Finally, the test bench and the technical developments are presented. They enable the performance of repeatable cartographies experiments which can be used to characterise music instruments. Finally, experimental and numerical results are compared in order to highlight the defaults and the qualities of the proposed model.
20

Automatizované měřící pracoviště letecké rádiové stanice R-863 / Automatic test setup for airborne radio-communication system R-863

Kropáček, Ondřej January 2012 (has links)
The aim of this thesis is design and realization of automatic test bench for parameters analysis of airborn radio-communication system R-863. Firstly we have taken up principles of the analysis properties of the radio system R-863. Then we proposed test bench for parameters analysis. In the next step we realize and integrate the digital control panel into the test bench. In harmony with the previous steps we have made program and software for the automatic test bench. Finally we make the user manual, which is easy to use.

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