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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

Study of different fuel injection and air management strategies as a tool for emissions control in a compression ignition engine (Diesel engine)

Estepa Ruiz, Daniel 26 November 2018 (has links)
En la actualidad, la industria del transporte es la encargada de satisfacer las necesidades logísticas del mundo. Los combustibles fósiles continúan siendo la principal fuente de energía de esta industria, y el motor Diésel, una de las tecnologías principales en la transformación de la energía química de estos combustibles en energía mecánica a través del proceso de combustión. Asociado a este proceso de transformación de la energía, un conjunto de efectos indeseados como las emisiones contaminantes o los gases de efecto invernadero han hecho movilizar a la comunidad científica. Dicha comunidad, ha realizado importantes esfuerzos en la investigación de soluciones limpias y eficientes que ayuden a minimizar los efectos indeseados del uso del motor Diésel. Sumado a los esfuerzos en la investigación, diferentes organizaciones gubernamentales han generado normativas que regulan estas emisiones contaminantes y la industria del motor ha reaccionado integrando soluciones tecnológicas que han hecho evolucionar la configuración original del motor Diésel. Debido a razones principalmente geopolíticas, el desarrollo económico a nivel mundial no se ha dado de manera homogénea, y en la actualidad, existe una disparidad global en cuanto a las exigencias en normativa de emisiones y la implementación de tecnologías para su control, siendo estas afectadas principalmente por sus costos. Es en este contexto donde se enmarca esta tesis doctoral, cuyo objetivo principal es el estudio de diferentes estrategias de inyección y de renovación de la carga como herramienta de control de emisiones en motores de encendido por compresión, teniendo en cuenta el costo de su integración. Se busca poder definir los límites de estas estrategias de bajo costo, determinando así su potencial real en la futura normativa de los mercados emergentes. Para abordar dicho objetivo, la tesis se ha desarrollado en tres etapas. En la primera, se ha realizado una aproximación teórico-experimental a las estrategias de inyección mediante modelado 3D-CFD y ensayos paramétricos en motor que permiten establecer como los parámetros de inyección responden al objetivo planteado. En la segunda etapa, se han estudiado las estrategias de renovación de la carga. Primero desde el modelado 1D para luego su posterior evaluación mediante su ensayo experimental en motor definiendo de esta manera las ventajas e inconvenientes de cada estrategia. En la tercera y última etapa, se han combinado todas las estrategias previamente estudiadas desde una aproximación experimental. De esta manera se puede alcanzar el objetivo de la tesis doctoral donde se ha comprobado la viabilidad de estas estrategias de bajo costo y se ha determinado su verdadero potencial como herramientas de control de las emisiones contaminantes. / En l'actualitat, la indústria del transport és l'encarregada de satisfer les necessitats logístiques del món. Els combustibles fòssils continuen sent la principal font d'energia d'aquesta indústria, i el motor Diésel, una de les tecnologies principals en la transformació de l'energia química d'aquests combustibles en energia mecànica a través del procés de combustió. Associat a aquest procés de transformació de l'energia, un conjunt d'efectes indesitjats com les emissions contaminants o els gasos d'efecte hivernacle han fet mobilitzar a la comunitat científica. Aquesta comunitat, ha realitzat importants esforços en la recerca de solucions netes i eficients que ajuden a minimitzar els efectes indesitjats de l'ús del motor Diésel. Sumat als esforços en la recerca, diferents organitzacions governamentals han generat normatives que regulen aquestes emissions contaminants i la indústria del motor ha reaccionat integrant solucions tecnològiques que han fet evolucionar la configuració original del motor Diésel. A causa de raons principalment geopolítiques, el desenvolupament econòmic a nivell mundial no s'ha donat de manera homogènia, i en l'actualitat, existeix una disparitat global quant a les exigències en normativa d'emissions i la implementació de tecnologies per al seu control, sent aquestes afectades principalment pels seus costos. És en aquest context on s'emmarca aquesta tesi doctoral, que el seu objectiu principal és l'estudi de diferents estratègies d'injecció i de renovació de la càrrega com a eina de control d'emissions en motors d'encès per compressió, tenint en compte el cost de la seua integració. Se cerca poder definir els límits d'aquestes estratègies de baix cost, determinant així el seu potencial real en la futura normativa dels mercats emergents. Per a abordar dita objectiva, la tesi s'ha desenvolupat en tres etapes. En la primera, s'ha realitzat una aproximació teòric-experimental a les estratègies d'injecció mitjançant modelatge 3D-CFD i assajos paramètrics en motor que permeten establir com els paràmetres d'injecció responen a l'objectiu plantejat. En la segona etapa, s'han estudiat les estratègies de renovació de la càrrega. Primer des del modelatge 1D per a després la seua posterior avaluació mitjançant el seu assaig experimental en motor definint d'aquesta manera els avantatges i inconvenients de cada estratègia. En la tercera i última etapa, s'han combinat totes les estratègies prèviament estudiades des d'una aproximació experimental. D'aquesta manera es pot aconseguir l'objectiu de la tesi doctoral on s'ha comprovat la viabilitat d'aquestes estratègies de baix cost i s'ha determinat el seu vertader potencial com a eines de control de les emissions contaminants. / Nowadays, the transport industry is responsible for accomplish the world's logistics requirements. Fossil fuels continue to be the main source of energy for this industry, and the Diesel engine, one of the main technologies in the transformation of the chemical energy of these fuels into mechanical energy through combustion. Associated with this process of energy transformation, a set of undesired effects such as pollutant emissions or greenhouse gases have challenged the scientific community that has made significant research efforts aiming clean and efficient solutions. Added to the scientific community efforts, different governmental organizations have created regulations in order to control these pollutant emissions and the engine industry has reacted by integrating technological solutions that have evolved the original configuration of the Diesel engine. Due mainly to geopolitical reasons, economic development worldwide has not occurred in a homogeneous manner, and currently, there is a global disparity regarding the requirements in emission regulations and the implementation of technologies for their control, mainly driven by their costs. It is in this framework where is set this doctoral thesis, with the main objective to study different injection and air management strategies as a tool for emission control in compression ignition engines, taking into account the cost of their integration. The aim is to be able to define the limits of these low-cost strategies, thus determining their real potential in the future regulations of emerging markets. To address this objective, the thesis has been developed in three stages. In the first one, a theoretical-experimental approach to the injection strategies has been carried out using 3D-CFD modeling and parametric engine tests which allow us to establish how the injection parameters help to reach the depicted thesis objective. In the second stage, the air management strategies have been studied. First, from the 1D modeling point of view in order to select the best option for this platform, and later to proceed with the experimental validation of this selection. Through the described approach is possible defining the advantages and disadvantages of each air management strategy. In the third and final stage, all previously studied strategies have been combined from an experimental approach. In this way, the evaluation of these cost-effective strategies has been defined and the fully potential as a tool for emissions control has been determined thus the objective of the doctoral thesis could be achieved. / Estepa Ruiz, D. (2018). Study of different fuel injection and air management strategies as a tool for emissions control in a compression ignition engine (Diesel engine) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113076 / TESIS
2

Automatizované nastavení regulátoru pohonu / Automated tuning of drive controller

Adamec, Matúš January 2017 (has links)
This thesis deals with automated tuning of drive controller. To achieve this goal, system identification is needed. Therefore, the issue of identification is described at the beginning of this thesis. Spectral analysis was selected from many described methods. It was implemented in Matlab and also in C# language where was used averaging and Blackman-Tukey method. The C# application is linked to Beckhoff TwinCAT 3 and TwinCAT 2 runtime sytems that enable connections with real drive. Next, the problem of drive regulation is discussed and the results of using spectral analysis on real drives are shown. At the end of the thesis is described the algorithm of setting the speed controller with different types of frequency converters.
3

Metodologia para re-sintonia de controladores PID industriais

Fernandes J?nior, Francisco Guerra 17 February 2006 (has links)
Made available in DSpace on 2014-12-17T14:55:57Z (GMT). No. of bitstreams: 1 FranciscoGFJ.pdf: 2262425 bytes, checksum: 03d70ce4ca2d284516ec0c9c15922fbf (MD5) Previous issue date: 2006-02-17 / The present work has as objective to present a method of project and implementation of controllers PID, based on industrial instrumentation. An automatic system of auto-tunning of controllers PID will be presented, for systems of first and second order. The software presented in this work is applied in controlled plants by PID controllers implemented in a CLP. Software is applied to make the auto-tunning of the parameters of controller PID of plants that need this tunning. Software presents two stages, the first one is the stage of identification of the system using the least square recursive algorithm and the second is the stage of project of the parameters of controller PID using the root locus algorithm. An important fact of this work is the use of industrial instrumentation for the accomplishment of the experiments. The experiments had been carried through in controlled real plants for controllers PID implemented in the CLP. Thus has not only one resulted obtained with theoreticians experiments made with computational programs, and yes resulted obtained of real systems. The experiments had shown good results gotten with developed software / O presente trabalho tem como objetivo apresentar um m?todo de projeto e implementa??o de controladores PID, baseado em instrumenta??o industrial. Ser? apresentado um sistema autom?tico de re-sintonia de controladores PID, para sistemas de primeira e segunda ordem. O software apresentado neste trabalho ? aplicado em plantas controladas por controladores PID implementados num CLP. O software ? aplicado para fazer a auto-sintonia dos par?metros do controlador PID de plantas que necessitem desta sintonia. O software apresenta duas etapas, a primeira ? a etapa de identifica??o do sistema utilizando o algoritmo dos m?nimos quadrados recursivos e a segunda ? a etapa de projeto dos par?metros do controlador PID utilizando o algoritmo do m?todo do lugar das ra?zes. Um fato importante deste trabalho ? a utiliza??o de instrumenta??o industrial para a realiza??o dos experimentos. Os experimentos foram realizados em plantas reais controladas por controladores PID implementados em um CLP. Assim n?o se tem apenas resultados te?ricos obtidos de experimentos feitos com programas computacionais, e sim resultados obtidos de sistemas reais. Os experimentos mostraram bons resultados obtidos com o software desenvolvido
4

Electrochemical Energy Conversion and Storage through Solar Redox Flow and Superoxide Batteries

McCulloch, William David 26 July 2018 (has links)
No description available.
5

Progrès en thermométrie quantitative aux échelles micro et nanométriques par microscopie thermique à balayage (SThM) / Advances in quantitative micro/nanoscale thermometry using scanning thermal microscopy

Nguyen, Tran Phong 18 January 2018 (has links)
Les caractérisations thermiques à l'échelle nanométrique restent un défi depuis l'émergence de dispositifs nano structurés. Ayant des avantages en termes de résolution latérale par rapport aux techniques de champ lointain, la microscopie thermique à balayage est devenue un outil essentiel pour la caractérisation locale des propriétés thermiques des matériaux. Dans le cadre du projet européen « Quantiheat », plusieurs laboratoires ont travaillé ensemble pour essayer de comprendre et d'obtenir des mesures quantitatives couvrant les échelles spatiales allant du micro au nanomètre.Ce document contient six chapitres avec quatre parties principales, dans lesquelles des sondes SThM à thermocouples microfilaires ont été utilisées pour améliorer nos connaissances en thermométrie quantitative à cette échelle. Ce type de sonde a été développé et amélioré pendant plusieurs années. Nous démontrons qu'il est adapté pour mesurer la température d’échantillons actifs ainsi que la conductivité thermique d’échantillons passifs.Grâce à la thèse, la dernière version du microscope (matériel, logiciel) et la conception de la sonde sont présentés. Fixé sur un diapason en quartz, la force de contact pointe-échantillon peut être quantifiée. Placé dans une chambre à vide, ce système permet un contrôle complet des paramètres prédominants sur la mesure, tels que la pression de l'air et la force de contact. Les mesures en modes actif et passif ont pu être menées grâce aux échantillons fournis par les partenaires du projet « Quantiheat » afin de démontrer que des mesures quantitatives sont envisageables. En changeant les conditions ambiantes allant du vide primaire à la pression ambiante, les mécanismes de transfert de chaleur de l'échantillon-pointe ont été analysés en détail pour mettre en évidence le rôle prépondérant de l'air et des conductions de contact solide-solide. / Thermal characterizations at nano-scale remain a challenge since the emergence of nano-structured devices. Having advantages in term of lateral resolution compared to far field techniques, the scanning thermal microscopy has become an essential tool for local materials heat transport characterization. In the frame of the European Quantiheat Project, several laboratories have worked together trying to figure out and to obtain quantitative thermal measurements covering spatial scales from the micrometre to the nanometre.This document contains six chapters with four main parts, in which micro-wire thermocouple based SThM probes have been used to enhance our knowledge in quantitative thermometry at this scale. This kind of probe has been developed and improved for several years. We demonstrate that it is adapted for measuring temperature of active samples as well as thermal conductivity of passive samples.Through the dissertation, the last version of the microscope (hardware, software) and probe design are presented. Attached on a quartz tuning fork, the tip-sample contact force can be quantified. Placed in a vacuum chamber, this system permits a full control of predominant parameters on the measurement such as air pressure and contact force. Thanks to samples provided by Quantiheat partners, measurements in active and passive modes have been performed to demonstrate that quantitative measurements are feasible. By changing ambient conditions from primary vacuum to ambient pressure, the tip-sample heat transfer mechanisms have been analysed in detail to reveal the preponderant role of air and solid-solid contact conductions.
6

An Energy-aware multipath routing extension for heterogeneous Ad hoc networks

Lima Junior, Josias Barbosa de 05 1900 (has links)
Submitted by João Arthur Martins (joao.arthur@ufpe.br) on 2015-03-11T18:10:20Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao JOSIAS de LIMA JUNIOR.pdf: 4252506 bytes, checksum: 714cb7aa7e2dc62943c697bd35a222ed (MD5) / Approved for entry into archive by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-03-13T13:00:53Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao JOSIAS de LIMA JUNIOR.pdf: 4252506 bytes, checksum: 714cb7aa7e2dc62943c697bd35a222ed (MD5) / Made available in DSpace on 2015-03-13T13:00:53Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao JOSIAS de LIMA JUNIOR.pdf: 4252506 bytes, checksum: 714cb7aa7e2dc62943c697bd35a222ed (MD5) Previous issue date: 2013-05 / Recent years have witnessed the emergence of new communication techniques in Computer Science that use both wireless technologies and self-organizing features. Their combination eliminates the need for using pre-defined wired structures and prior configurations. In this work, we develop a simulated version, using the network simulator 3 (ns-3), of the Heterogeneous Technologies Routing (HTR) framework that is suitable for interconnecting devices in a heterogeneous ad hoc network, extending its supported heterogeneous technologies with the addition of WiMAX and LTE devices, proposes an extension to enable multipath routing over this framework and investigates the impact of tuning routing parameters on convergence interval and energy consumption. Although a large number of works exist that investigate the tuning of routing parameter settings, to the best of our knowledge, none of them investigate the impact of these on protocol convergence and energy consumption. Multipath HTR routing, the extension we propose, offers several benefits such as load balancing, fault tolerance, routing loop prevention, energy-conservation, low end-to-end delay, and congestion avoidance, among others. This work performs a comparative analysis of the proposed HTR extension, with the baseline HTR, and the widely used Optimized Link State Routing (OLSR) protocol. Moreover, we investigate the impacts of tuning the HELLO refresh interval and perform a comparative analysis of the tuned HTR with the OLSR protocol. Both evaluations are validated through the simulation of heterogeneous technologies such as WiMAX, 3GPP LTE and Wi-Fi. Results show that the multipath extension effectively improves the data delivery ratio, and reduces the end-to-end delay without major impact on network energy consumption. For the tuned HTR, results show that varying the HELLO refresh interval can improve the convergence of the protocol and reduce the energy consumption. / Recentemente, novas técnicas de comunicação surgiram que usam tecnologia sem fio e são capazes de se autoconfigurar. A combinação desses fatores elimina a necessidade de utilizar estruturas cabeadas e configurações pré-definidas. Neste trabalho, o autor desenvolve uma versão simulada, através do simulador de rede “network Simulator 3” (ns-3), do arcabouço “Heterogeneous Technologies Routing” (HTR), que se propõe à interconectar dispositivos em redes heterogêneas ad hoc, estendendo o seu suporte às tecnologias heterogêneas com a adição de dispositivos WiMAX e LTE, propõe uma extensão para fornecer um roteamento baseado em múltiplos caminhos (“Multipath”) e investiga o impacto de modificar os parâmetros de configuração do roteamento no tempo de convergência da rede e consumo de energia. Apesar de um grande número de obras existentes que investigam o impacto da mudança de parâmetros de configuração do roteamento, no meu conhecimento, nenhum deles investiga o impacto destes no tempo de convergência do protocolo e consumo de energia. O “Multipath HTR”, a extensão proposta, oferece vários benefícios como balanceamento de carga, tolerância a falhas, prevenção de “loops” de roteamento, conservação de energia, baixo atraso fim-a-fim, e evita o congestionamento, entre outros. Este trabalho faz uma análise comparativa da extensão ao HTR proposta, com a base do HTR, e o protocolo amplamente utilizado “Optimized Link State Routing” (OLSR). Além disso, o esse trabalho investiga o impacto de variar o intervalo de envio de mensagens de HELLO e realiza uma análise comparativa do HTR modificado (“Tuned HTR”) com o protocolo OLSR. As duas avaliações são realizadas através de simulação usando tecnologias heterogêneas como WiMAX, 3GPP LTE e Wi-Fi. Resultados mostram que a extensão de múltiplos caminhos proposta melhora a taxa de transmissão de dados, e reduz o atraso fim-a-fim sem maiores impactos no consumo de energia da rede. Para o “Tuned HTR”, resultados mostram que a variação do intervalo de envio de mensagens de HELLO pode melhorar a convergência do protocolo e reduz o consumo de energia.
7

Sintonia do filtro de Kalman para medição indireta das variáveis de estado no banho eletrolitico / Tunning of the Filter of Kalman for indirect measurement of the variable of state in the electrolytic bath

Braga, Carlos Augusto Pereira 07 April 2008 (has links)
Made available in DSpace on 2016-08-17T14:52:48Z (GMT). No. of bitstreams: 1 Carlos Augusto Pereira Braga.pdf: 1145854 bytes, checksum: 8898d3084e223e4e9ad52a8aa7363b01 (MD5) Previous issue date: 2008-04-07 / A tunning model for Kalman filter based on QR duality principle is presented to measure the state variables of the electrolytic bath in aluminium production cells. The main goal is to establish a set of filter gains that better represents the percentual of alumina in the bath. The filter bandwidth tunning is performed by increasing or decreasing the filter bandpass from the Q and R variations. The design and analysis of the Q and R covariance matrices are performed to find a pattern of the resistance variations that could be associated with the alumina concentration in the bath. The technical solution encloses on-line evaluation of the Kalman filter in order to prove its capableness of response when used to control real production cells. The Standard Kalman is coded upon a scalar form to reduce the use of computing resources when the filter is processed. The line current and pot voltage are directly read from the hardware interface and then converted in a third variable, the resistance, which is used to infer the alumina concentration in the bath. Moreover, the filter implementation goes in the direction of practical aspects limits of the indirect measurement system implementations, its robustness is appraised by observability, roundo® and modeling errors. / O controle da concentração de alumina no banho de cubas eletroliticas é de vital importância para um rendimento eficiente do processo de produção de aluminio. Este controle tem por objetivo promover, em uma visão macro, um retorno justificável perante ao planejamento global das metas de produção de uma fábrica de aluminio. O desenvolvimento de uma metodologia baseada no ajuste dos ganhos de um filtro tipo Kalman Padrão é o principal enfoque cientifico e tecnológico desta pesquisa. A sintese da metodologia é a implementação do filtro de Kalman Padrão e Escalar em um computador que controla a quantidade de alumina no banho eletrolitico. Considera-se as restrições de software e de hardware na implantação do algoritmo de Kalman no sistema que executa o controle de processo por computador. Desenvolve-se um modelo de sintonia do filtro de Kalman utilizando-se o principio da dualidade das matrizes Q e R. O objetivo é estabelecer um conjunto de ganhos que representem da melhor forma a quantidade de alumina dentro da cuba. Assim, faz-se uma análise considerando-se mudanças nas matrizes Q e R, e apresenta-se os resultados obtidos. Analisa-se a largura de banda do filtro, verificando-se diminuição ou aumento de banda na medida que as matrizes Q e R sofrem alterações em seus elementos. As estratégias de monitoramento são verificadas para diversas situações de operação(dinâmica) da planta, e as variações paramétricas do modelo são levadas em consideração para garantirmos uma operação robusta e estável do filtro. O desempenho do filtro é verificado em paralelo com um sistema de filtragem e de controle historicamente utilizados na estimação do percentual de alumina no banho eletrolitico.
8

Adaptivní řízení varny malého pivovaru / Adaptive control of small brewery

Kalivoda, Jakub January 2014 (has links)
This final thesis deals with adaptive control of small brewery. Contains a short description of brewing technology and adaptive control. Includes design of small brawery and control system based on STM32F407 Cortex-M4 microcontroller. For online identification is used Recursive Least Squares Method. The controller function perform a modified PSD controller with filtered derivative component, reducing the first overshot and dynamic antiwindup. The proposed adaptive controller is implemented into microcontroller. Created device i used for semi-automatic beer production.
9

Conception d'une clarinette logique / Conception of a logical clarinet

Guilloteau, Alexis 30 September 2015 (has links)
Le processus de conception des instruments à anche simple, élaboré au fil des siècles par les facteurs, est essentiellement basé sur des lois de comportement empiriques qui résultent de l’arbitrage des clarinettistes. Leurs critères subjectifs d’appréciation semblent être aussi bien alimentés par des descripteurs acoustiques (fréquence de jeu, spectre perçu, dynamique) que par l’aisance dans leur contrôle. Les connaissances actuelles en propagation guidée dans les réseaux de trous latéraux, offrent une base nécessaire à la prédiction du comportement acoustique linéaire du résonateur de l’instrument. Nous cherchons, à l’aide de ceux-ci, à proposer une méthode d’optimisation géométrique (positions et dimensions des trous latéraux) afin d’atteindre une retranscription objective, la plus proche possible, des critères d’appréciation du musicien. L’heuristique suivie au cours de cette étude vise à affiner les modèles de comportement ainsi que la construction des critères objectifs d’appréciation à l’issue de chaque réalisation d’un prototype de clarinette jusqu’à leur validation expérimentale. Avec l’aide d’un facteur d’instrument, deux prototypes ont été réalisés et nous exposerons les avantages et inconvénients des procédures d’optimisation appliquées à chacun d’eux. / Single reed instruments conception process developed by instrument makers, is essentially based on empirical laws obtained from their interaction with musicians. Some of the subjectives criteria seems to be defined by both acoustic descriptors(like playing frequency, radiating spectrum and musical dynamics for exemple) and the ease of their control. Present knowledges in guided wave propagation in tone hole lattice are a necessary background to explain linear behavior of the clarinet. We aim to develop an optimisation method for clarinet geometrical variables in a way to reach the best objective translation of the clarinetists appraisal criteria. Then, the followed heuristic in this study consist in the enhancement of the acoustic behavior laws in parallel with the development of objective criteria after each logical clarinet making, until their experimental validation. The collaborative work with an instrument maker, helps us to make 2 prototypes with each specific procedure depicted in this document.

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