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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

Modellbaserad temperaturregleringav partikelfiltrets regenereringsprocess / Model based control of particulate filter regeneration

Forsberg, Thomas, Woxlin, Martin January 2011 (has links)
Due to increasing regulations regarding new diesel vehicles particulate matteremissions the new Scania truck, Scania Euro 6, has been equipped with a particulatefilter. This component effectively stores the particles in the exhaust gas but must becleaned in order to prevent itself from clogging. The filter is cleaned through aprocess named regeneration which is a thermodynamic process in which thetemperature of the filter is raised through fuel supplied to the exhaust gas.The purpose of this thesis is to contribute to the development of improved controlstrategies of the temperature during the regeneration process through thedevelopment of model-based controllers. These controllers are designed in order tohave good performance in stationary as well as automatic regeneration.In order to develop these model-based controllers a model of the system isconstructed. The model is described as a linear thermodynamic grey-box model withflow varying parameters, showing good results in validation.The model provides a simulation environment during the controller design, which isfocused around the development of linear regulators with the exhaust gas mass flowas a scheduling variable whose size determines controllers’ mode of operation. Basedon this approach an IMC controller and a PI controller with a combined feedforwardterm are developed and analyzed. Both controllers show good performance in termsof robustness and reference tracking. The authors' firm opinion is that controlstrategies with the exhaust gas mass flow as a scheduling variable is suitable forkeeping control of the temperature in the particulate filter during regeneration.
2

Contribution des composés organiques volatils (COVs) provenant des émissions des véhicules aux aérosols organiques secondaires (AOS) et à la pollution urbaine / Contribution of volatile organic compounds (VOCs) from vehicle emissions to secondary organic aerosol (SOA) and urban pollution

Martinez, Alvaro 29 March 2019 (has links)
Le secteur des transports est fondamental pour le développement économique d'un pays et pour assurer la communication et une bonne qualité de vie. Cependant, le transport routier conduit à une grave dégradation de la qualité de l'air et contribue au réchauffement de la planète. Parmi tous les polluants, les particules fines et ultrafines, émises par les véhicules mais également formées dans l'atmosphère sont considérées toxiques. De nombreuses études montrent que l’exposition chronique aux particules fines favorise le développement de pathologies respiratoires et cardiovasculaires. Les précurseurs gazeux, les principaux mécanismes réactionnels ainsi que les transformations physiques que les Aérosol Organiques Secondaires (AOS) subit dans l'atmosphère restent encore incertains. La présente étude porte principalement sur la caractérisation des polluants primaires émis par les échappements automobiles et les transformations photochimiques des COV / COVI. Les émissions des voitures ont été évaluées à l’aide d’un banc à rouleau au laboratoire de l’IFSTTAR. Les mesures du nombre de particules ont été effectuées directement au niveau de l’échappement. Pour les véhicules GDI, PN0.23 (<23 nm) représentait en moyenne 20- 30% du nombre total de particules émises, alors que pour les voitures diesel, cette fraction était bien inférieure (≈10-15%). Lors des régimes à grande vitesse (autoroutier Artemis) des véhicules diesel, une régénération passive de Filtre à Particules (FAP) a été observée. Les particules émises étaient principalement constituées de suie, de bisulfate et de matière organique. Les particules émises par les voitures essence à injection directe étaient principalement composées de Black Carbon (BC) et de gouttelettes organiques contenant des éléments. Pendant le démarrage à froid, les voitures GDI émettent des concentrations importantes de BC et de matière organique. Les émissions d'hydrocarbures ont également été étudiées. Les véhicules GDI ont émis des concentrations importantes de THC lors du démarrage à froid. Parmi les composés aliphatiques, des composés jusqu’à la C15 ont été identifiés, confirmant l’émission d'hydrocarbures plus lourds par les voitures diesel. La deuxième partie de ce travail consistait à étudier la transformation atmosphérique de certains COV (toluène, naphtalène, cyclohexane, nonane) émis par les véhicules Euro 5 et Euro 6 et à déterminer le potentiel de formation d’AOS de ces composés. Les composés choisis ont été photo-oxydés (seuls et en mélange) dans un réacteur à tube à flux d'aérosol afin de simuler leur vieillissement atmosphérique. Les résultats majeurs suggèrent: (1) des composés aromatiques et des HAP représentent les composés avec le plus fort potentiel de formation d'AOS ; (2) la température a un impact important sur la formation et le rendement d'AOS ; (3) la présence de particules préexistantes a un effet positif sur la formation d'AOS; (4) il a été constaté que la présence des NOx affectaient négativement la formation d'AOS ; (5) la formation d'AOS de mélanges de COV est fortement influencée par la fraction de composé aromatique. Certains des produits identifiés dans la phase particulaire n’ont jamais été signalés auparavant. La dégradation des composés aromatiques en régime de NOx moyen a produit des composés nitro-aromatiques identifiés à la fois en phase gazeuse et en phase particulaire. Cette thèse contribue à enrichir la base de données d’émissions des voitures, encore limitée aux véhicules Euro 5 et Euro 6. La spéciation des composés non réglementés aidera à mieux comprendre le budget atmosphérique d’AOS et les impacts des voitures sur la qualité de l’air. Enfin, l’étude de photoxydation de COV primaires (seuls, mélange et émissions complètes) conduira à une meilleure compréhension de la formation d’AOS / The transport sector is fundamental to the economic development of a country and to ensure communication and a good quality of life. However, road transport contributes significantly to global warming and leads to serious degradation of the air quality. Among all pollutants, fine and ultrafine particles, emitted by vehicles but also formed in the atmosphere are considered as potentially toxic. Many studies show that chronic exposure to fine particles promotes the development of respiratory and cardiovascular diseases. The main gaseous precursors, the atmospheric chemical pathways as well as the chemical composition and the physical transformations that secondary organic aerosol (SOA) undergo in the atmosphere, remain poorly understood. The main aim of this work was on one side to improve the knowledge about primary pollutants emitted from Euro 5 and Euro 6 diesel and gasoline passenger cars and on the other side to investigate the photochemical transformations of the VOCs/IVOCs emitted from these cars. Passenger car emissions have been evaluated on a chassis dynamometer test bench at the IFSTTAR laboratory. Particle number measurements were carried out directly at the tailpipe. For GDI vehicles PN0.23 (< 23 nm) represented on average 20 -30 % of total particle number emitted, while for diesel cars, this fraction was considerably lower (≈10-15%). During high speed regimes (Artemis motorway) of diesel passenger cars Diesel Particulate Filter (DPF) passive regeneration was observed. These periods were characterized by a high particle number concentration; their composition was mainly soot, bisulfate and some organic material. PM emitted from gasoline DI passenger cars was mainly composed by BC and some organic droplets containing traces of other elements. During cold start GDI cars do emit important concentrations of BC and organic material. Emission of hydrocarbons has also been investigated. Gasoline DI emitted important concentration of THCs during cold start. Among the aliphatic compounds, families until C15 have been identified, confirming emission of heavier HCs from diesel cars. The second aim of this work was the study of atmospheric degradation of selected VOCs (toluene, naphthalene, cyclohexane, nonane) emitted from Euro 5 and Euro 6 vehicles and to determine the SOA formation potential of these compounds under different environmental conditions. The chosen compounds have been photoxidized (alone and in mixture) in an Aerosol Flow Tube (AFT) reactor in order to simulate VOCs atmospheric aging. The results suggest: (1) aromatic and PAHs compounds, own highest potential to form SOA; (2) the temperature has an important impact on SOA formation and yield; (3) the presence of pre-existing seed particles has, in general, a positive effect on SOA formation and (4) NOx has been found to negatively affect SOA formation; (5) SOA potential formation of VOC mixtures is highly influenced by the fraction of aromatics. Some of the products identified in the particle phase have never been previously reported. Degradation of aromatic compounds under medium NOx regime produced nitro-aromatic compounds identified both in the gas and particle phase. This PhD contributes to enrich vehicle emissions database, still limited for Euro 5 and Euro 6 cars. Speciation of non-regulated compound will help to better understand atmospheric SOA budget and car emissions air quality impacts. By last, the photoxidation study of primary VOCs (alone, mixture and full emissions) will lead to a better comprehension of SOA formation from vehicles
3

Zvýšení efektivity montážního pracoviště / Efficiency increasing of assembly cell

Dvořák, Radim January 2017 (has links)
This diploma thesis deals with increasing the efficiency of the assembly workplace (production line). Thesis gradually discusses with lean production, their basic methods and the EURO VI emission standard, which is closely related to the produced product. In the main part, an analysis of the current state is performed with the help of the above-mentioned methods and a proposal of solutions to ensure efficiency. On the base of these findings, the automation of the test station is proposed, including a 3D model, drawing documentation, phases of implementation and real cost calculations with a final assessment of efficiency, return of investments and risk analysis. The second elaborated complementary variant deals with the ergonomics of the production line and includes a 3D model of newly designed tables, real calculations and final economic evaluation.

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