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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

Recycling of Textile and Plastic from an Interior Vehicle Component / Återvinning av textil och plast från en interiör fordonskomponent

Wennerstrand, Esther January 2021 (has links)
På grund av den rådande klimatförändringen och de globala problem som plast orsakar i miljön blir det allt viktigare att dagens linjära materialanvändning ändras till en cirkulär användning. Inom fordonsindustrin har kravet på ökad tillgänglighet och kvalitet på återvunna material identifierats. Som följd startades forskningsprojektet Sustainable Vehicle Interior Solutions (SVIS) samordnat av RISE IVF där behovet av en mer hållbar produktion av fordonsinteriörer tas upp. Ett mål är att minska och återvinna produktionsavfall. Den här studien undersöker möjligheten att återvinna textil och plast från en interiör komponent av multimaterial, som i detta fall är en textilklädd plaststolpe. Stolpen är gjord av polykarbonat (PC)/poly(akrylnitril-butadien-styren) (ABS) plast och polyestertextil (PET). Mekanisk återvinning utfördes på den textilklädda stolpen. Möjligheten att separera textil från plast undersöktes och testades i en kvarn med en dammavskiljare. Prover innehållande olika mängder PET förberedes och återvanns för att studera påverkan av PET på materialegenskaperna. Två olika kompatibiliseringsmedel användes för att undersöka om blandningarnas kompatibilitet ökade. Hur väl textil separerats från plast analyserades genom jämförelse av bulkdensitet mellan proverna. För att undersöka effekten av kompatibiliseringsmedel och hur förekomsten av PET påverkar PC/ABS utfördes mekanisk testning, DSC och SEM. Resultaten visade att separationen av textil från plast inte var fullständig på grund av mycket hög vidhäftning mellan textilen och plasten. Bibehållna mekaniska egenskaper, förutom brottförlängning, erhölls för alla återvunna prover oavsett PET-mängd. Därför var det möjligt att dra slutsatsen om att förekomsten av PET inte påverkar materialets egenskaper negativt och att separation eller tillsats av kompatibiliseringsmedel inte är nödvändigt. Vidare visar resultaten att PET blir blandbar med PC men inte påverkar ABS-fasen. Kemisk återvinning genom glykolys utfördes på svart och beige polyestertextil av PET erhållet som avklipp från produktionen av stolparna. Glykolysen utfördes i laboratorieskala med etylenglykol (EG) som lösningsmedel. Reaktionen ägde rum vid 230℃ under 1 timme med överskott av lösningsmedel och en Mg-Al blandad oxidkatalysator. Slutprodukten separerades från rester genom flera filtreringssteg och analyserades med DSC. Från resultatet observerades det att den erhållna slutprodukten var den önskade bis(2-hydroxyetyl) tereftalat (BHET) monomeren. Färgämnen från textilen fanns fortfarande kvar i monomeren efter depolymerisation. Därför utfördes avfärgning. För den svarta textilen testades adsorption med aktivt kol och extraktion med etylenglykol som avfärgningsmetoder. För den beige textilen utfördes enbart adsorption med aktivt kol. De avfärgade produkterna analyserades genom färgmätning och/eller genom jämförelse med varandra. Resultatet visade att adsorption med aktivt kol är en effektiv avfärgningsmetod för den beige textilen, men inte för den svarta textilen. Framgångsrik avfärgning av den svarta textilen erhölls istället genom extraktion med etylenglykol. Sammanfattningsvis, mekanisk återvinning av den textilklädda stolpen resulterar i bibehållna värden för de mekaniska egenskaperna hos det återvunna materialet, förutom för brottförlängnigen. Detta bör göra det återvunna materialet lämpligt för användning i fordonsapplikationer, men inte för återvinning i ett slutet kretslopp (closed loop recycling) på grund av säkerhetsaspekter hos stolpen. Om hög kraft appliceras måste materialet kunna ändra form utan att gå sönder. Återvinning genom glykolys visar potential för att den avklippta polyestertextilen kan återvinnas i ett slutet kretslopp eftersom den avfärgade monomeren skulle kunna ompolymeriseras till ny PET. Det kan undersökas i framtida studier. / Due to the current climate change and the global problems plastics cause in the environment, it becomes increasingly important that today’s linear use of materials is changed to a circular use. In the automotive industry, the demand for increased availability and quality of recycled materials has been recognized. Following this, the research project Sustainable Vehicle Interior Solutions (SVIS) coordinated by RISE IVF was started in which the need for a more sustainable production of vehicle interiors is addressed. An objective is to reduce and recycle production waste. This study investigates the possibility to recycle textile and plastic from an interior multi-material component which in this case is a textile dressed plastic pillar. The pillar is made of polycarbonate (PC)/poly(acrylonitrile butadiene styrene) (ABS) plastic and polyester (PET) textile.  Mechanical recycling was performed on the textile dressed pillar. The possibility to separate textile from plastic was investigated and tested in a mill with a dust separator. Samples containing different amounts of PET were prepared and recycled to study the influence of PET. Two different compatibilizers were used to investigate potential improvement in compatibility of the blends. The level of separation of textile from plastic was analyzed by comparison of bulk density between the samples. To investigate the effect of compatibilizers and how the presence of PET influences the PC/ABS, mechanical testing, DSC and SEM were performed. The results showed that the separation of textile from plastic was not complete due to very high adhesion between the textile and plastic. Retained mechanical properties, except for the strain at break, were obtained for all recycled samples. Therefore, it could be concluded that the presence of PET does not affect the properties of the material negatively and separation or addition of compatibilizer is unnecessary. The results further show that PET becomes miscible with PC but does not affect the ABS phase. Chemical recycling through depolymerization with glycolysis was performed on black and beige polyester (PET) textile waste obtained as cut-off from the production of the pillars. The glycolysis was performed in lab-scale with ethylene glycol (EG) as solvent. The reaction took place at 230℃ for 1h with excess of solvent and a Mg-Al mixed oxide catalyst. The final product was separated from residues through several filtration steps and analyzed with DSC. From the result it could be observed that the obtained final product was the desired bis(2-hydroxyethyl) terephthalate (BHET) monomer. Dyes from the textile were still present in the monomer after depolymerization. Therefore, decolorization was performed. For the black textile, adsorption with active carbon and extraction with ethylene glycol were tested as decolorization methods. For the beige textile, solely adsorption with active carbon was performed. The decolorized products were analyzed by color measurement and/or through comparison to each other. The result showed that adsorption with active carbon is an effective decolorization method for the beige textile, but not for the black textile. Successful decolorization of the black textile was instead obtained by extraction with ethylene glycol.  To conclude, mechanical recycling of the textile dressed pillar results in retained values of the mechanical properties of the recycled material, except for the strain at break. This should make the recycled material suitable for use in automotive application, though not closed loop recycling because of safety aspects of the pillar. If high force is applied, the material needs to be able to change shape without breaking. Recycling through depolymerization shows potential for closed loop recycling of the polyester textile cut-off since the decolorized monomer could be repolymerized into new PET. This could be investigated in future studies.
62

[de] ENTWICKLUNG EINES KOLLISIONSVERMEIDUNGSSYSTEM BASIEREND AUF EINER FUZZY REGELUNG / [en] DEVELOPMENT OF AN AUTONOMOUS COLLISION AVOIDANCE SYSTEM BASED ON FUZZY CONTROL / [pt] DESENVOLVIMENTO DE UM SISTEMA AUTÔNOMO DE EVASÃO DE COLISÕES BASEADO EM CONTROLE FUZZY

RAFAEL BASILIO CHAVES 09 February 2018 (has links)
[pt] O presente trabalho apresenta um conceito para um sistema de evasão de colisões, simulado usando modelos 3D de três veículos diferentes implementados em MATLAB. Dois destes veículos foram parametrizados com dados genéricos, caracterizando automóveis de médio e grande porte. Em seguida, utilizados para realização de simulações iniciais e demonstração de conceitos. O terceiro conjunto de dados foi construído com informações do Apollo N, um veículo super esportivo. Estes diferentes conjuntos de dados foram utilizados para avaliar a capacidade do controlador de trabalhar com veículos de diferentes portes e dinâmicas de direção. A abordagem para acionar o sistema baseia-se no cálculo do tempo para a colisão (TTC; timeto- collision). O conceito foi adotado para detectar situações onde o motorista não é capaz de evitar um acidente. Depois de ser acionado, o sistema deve decidir qual manobra é a mais apropriada, dadas as condições de aderência da pista e o risco associado. O primeiro objetivo deste trabalho é desenvolver um sistema autônomo de frenagem que deve ser capaz de avaliar o risco de uma possível colisão e decidir se o condutor é capaz de evitá-la. Uma vez que o motorista não tenha tempo suficiente para reagir, o sistema deve acionar os freios automaticamente a fim de evitar um possível acidente. Além disso, o veículo possui um sistema anti-travamento (ABS), desenvolvido usando controle Fuzzy. O desempenho do controlador ABS foi avaliado em simulações usando os conjuntos de dados e testado em um veículo em escala. Em casos mais críticos, quando há baixa aderência, o veículo não é capaz de frear em uma distância razoável. Levando-se em consideração tal situação, um controle autônomo de esterçamento também foi desenvolvido, visando a possibilidade de uma manobra alternativa de evasão. Este segundo sistema foi avaliado em simulações utilizando veículos com características subesterçantes e sobreesterçantes. Os resultados mostraram que o controle de esterçamento foi capaz de realizar manobras evasivas produzindo valores razoáveis de acelerações laterais, em veículos com diferentes dinâmicas de direção. / [en] This work presents a concept for a collision avoidance system simulated using 3D-models of three different vehicles implemented in MATLAB. Two of the vehicle data sets were built with generic information, used to characterize mid-size and full-size vehicles. These standard vehicles were used in initial simulations and for demonstration of some concepts. The third data set was built with information from the Apollo N, a super sportive car. These different data sets were used to evaluate the controller s capacity to work with a range of vehicles, with different sizes and driving characteristics. The approach for triggering the system is based on the time-to-colision (TTC) estimation. This concept was adopted to recognize when the driver is not able to avoid an accident. After being triggered, the system must decide which maneuver is the most appropriate for the given friction and risk conditions. The first goal of this work is to develop an autonomous braking system which evaluates the risk of a possible collision and decides if the driver is able to avoid it. Once the driver has not enough time to react, the system must trigger the brakes automatically in order to avoid the accident. The vehicle is equipped with an embedded Anti-lock Brake System (ABS) developed using Fuzzy control. The ABS controller s performance was evaluated in simulations using the data sets and tested in a scaled vehicle. In more critical cases, when there is low friction, the vehicle is not able to brake in a reasonable distance. Considering this situation, an autonomous steering control was implemented in order to make an alternative avoidance maneuver. This second system was evaluated in simulations using vehicles with understeering and oversteering characteristics. The results pointed out that the autonomous steering control was able to perform avoidance maneuvers in a reasonable range of lateral accelerations, in vehicles with different driving tendencies. / [de] Die vorliegende Arbeit prasentiert ein Konzept fur ein Kollisionsvermeidungssystem. Dieses wird anhand von drei verschiedenen 3DFahrzeugmodellen mit Hilfe von MATLAB simuliert. Zwei der FahrzeugDatensatze basieren auf generischen Informationen, die jeweils ein Automobil der Mittelklasse und der Oberklasse reprasentieren. Diese Standardfahrzeuge wurden fur anfangliche Simulationen und zur Demonstration einiger Konzepte verwendet. Das dritte Fahrzeugmodell wurde mit Hilfe der Daten des Sportwagens Apollo N aufgebaut. Durch die Verwendung der verschiedenen Datensatze soll die Funktionsfahigkeit der Regelung auch bei verschiedenen Fahrzeugtypen mit unterschiedlichen Dimensionen und Fahreigenschaften uberpruft werden.Die Grundlage zum Auslosen des Systems ist die Abschatzung der Zeit bis zur Kollision (TTC; time-to-collision). Dieses Konzept wurde aufgegriffen, um zu entscheiden, wann der Fahrer nicht mehr in der Lage ist einen Unfall zu vermeiden. Nachdem das System ausgelost wird muss dieses anhand der Traktionsverhaltnisse und Gefahrensituation entscheiden, welches Manover am besten geeignet ist. Das erste Teilziel ist die Entwicklung eines autonomen Bremssystems, welches eine bevorstehende Kollision erkennen muss und entscheidet ob der Fahrer die Kollision eigenstandig vermeiden kann. Sobald der Fahrer nicht mehr genug Zeit hat selbst zu reagieren, muss das System die Bremsen automatisch betatigen um den Unfall zu vermeiden. Hierzu ist das Fahrzeug mit einem Antiblockiersystem (ABS) ausgestattet. Dieses wurde mit Hilfe eines Fuzzy-Kontrollers realisiert. Die Funktionstuchtigkeit der ABS-Regelung wurde mit Simulationen und anhand eines realen, skalierten Fahrzeugmodells getestet. In kritischen Situationen, kann es aufgrund der Traktionsverhaltnisse vorkommen, dass das Fahrzeug nicht mehr in der Lage ist innerhalb einer ausreichenden Strecke zum Stehen zu kommen. Um fur solche Situationen ein alternatives Ausweichmanöver anwenden zu konnen, wurde ein automatischer Lenkeingriff implementiert. Dieses System wurde anhand von Simulationen an Fahrzeugmodellen mit Ubersteuernden und Untersteuernden Eigenschaften uberprüft. Die Ergebnisse zeigten, dass die automatische Lenkeingriff-Regelung in der Lage war auch bei Fahrzeugen mit unterschiedlichen Fahreigenschaften Ausweichmanöver unter Einhaltung angemessener Querbeschleunigungen durchzufuhren.
63

Valorisation des polymères styréniques issus des déchets d’équipements électroniques et électriques / Recycling of styrenic polymers from waste of electric and electronic equipments

Chevallier, Céline 29 November 2012 (has links)
L‟objectif de cette thèse est de valoriser les polymères styréniques issus des déchets d‟équipements électroniques et électriques. Les polymères considérés sont le polystyrène (PS), le polystyrène choc (HIPS), le poly(acrylonitrile-butadiène-styrène) (ABS), l'ABS couplé avec du polycarbonate (ABS/PC) et le poly(styrène-acrylonitrile) (SAN). Une étude préliminaire a permis de définir deux mélanges à compatibiliser : le mélange PS/ABS et le mélange PS/PC. Pour le mélange PS/ABS, la voie de compatibilisation ionique est étudiée. L‟ajout d‟un copolymère présentant une structure ionique et la création d‟un réseau in-situ sont tentés. Ces deux voies n‟ont pas donné de résultats concluants en termes d‟amélioration des propriétés finales du mélange. Le mélange PS/PC est lui compatibilisé par ajout d‟un copolymère polystyrène bloc-poly(éthylène-butylène)-bloc-polystyrène greffé PC. Ce copolymère est tout d‟abord créé en mélangeur interne, afin d‟étudier différents catalyseurs susceptibles d‟initier le greffage, puis l‟extrusion réactive est utilisée pour synthétiser ce copolymère à grande échelle. Plusieurs taux de copolymère sont alors introduits dans le mélange PS/PC et l‟amélioration des propriétés et des microstructures prouve son effet compatibilisant / The aim of this work consists in the recycling of the styrenic polymers coming from waste of electric and electronic equipments. Polystyrene (PS), high impact polystyrene (HIPS), poly(acrylonitrile-butadiene-styrene) (ABS), its alloy with the polycarbonate (ABS/PC) and poly(styrene-acrylonitrile) (SAN) are considered. A preliminary study permits to choose two blends to study: PS/ABS and PS/PC. In the case of PS/ABS blend, the ionic way of compatibilization was studied. The addition of a copolymer containing an ionic structure and the creation of an ionic network in-situ are investigated. Both these attempts are not conclusive about the improvement of the final properties of the blend. The PS/PC blend is then compatibilized by adding a polystyrene-block-poly(ethylene-butylene)-block-polystyrene grafted polycarbonate. This copolymer is first created in an internal mixer, in order to study different catalysts able to initiate the grafting, and then the reactive extrusion is used to synthesize it on a large scale. Several amounts are introduced in the PS/PC blend and the improvement of the properties and microstructures proves its compatibilizing effect
64

Estudo do desempenho na frenagem de um bi-trem com suspensão em \"tandem\" e com ABS / Braking performance of a bi-trem with tandem axle and ABS

Polito, Rafael Ferreira 16 September 2005 (has links)
O bi-trem é um veículo cada vez mais comum no trânsito brasileiro. Por ser um veículo de grande porte, é capaz de se envolver em acidentes catastróficos caso o sistema de freio não esteja projetado de maneira adequada. Neste contexto é necessário um estudo que permita prever e otimizar o desempenho do sistema de freios para qualquer condição operacional. Para isso foi desenvolvida uma planilha de cálculos para estudar o desempenho da frenagem de um bi-trem. A planilha calcula a aderência que cada eixo utiliza, a desaceleração máxima desenvolvida pelo veículo, o espaço e o tempo de parada, a força de frenagem (e sua porcentagem) em cada eixo, a temperatura final do tambor, a eficiência do sistema de freios, as forças normais ao pavimento, a distribuição real e ideal das forças de frenagem e verifica se o cavalo mecânico e os semi-reboques se enquadram, respectivamente, nos diagramas 3 e 4 do anexo 10 da ECE-R13. Tais cálculos podem ser feitos com o veículo utilizando ou não ABS e com válvula sensível a carga nos semi-reboques e no \"tandem\" do cavalo mecânico. A planilha de cálculo foi aplicada em um veículo exemplo e os resultados são apresentados nesta dissertação. O sistema de freios desse veículo foi otimizado com a utilização da planilha, mostrando como ela pode ser de grande auxílio ao projetista. / The bi-trem (a vehicle similar to a twin trailler truck) is more and more common in the brazilians highways. Because it\'s a large and heavy vehicle it can cause catastrophics accidents if the brakes are not well developed. In this context it is necessary a study that allows to foresee and to optimize the performance of the brakes system for any operational condition. In this work an electronic spread sheet was developed in order to study the braking performance of a bi-trem. The spread sheet calcs the adhesion in each axle, the maximum deceleration, the braking space and the braking time, the braking force (and its percentage) in each axle, the final temperature of the drum, the brake system\'s efficiency, the normal forces, the actual and ideal brake force distribution, and verifies if the tractor and the semi trailers are fitted in the annex 10 of EGE-R13. The reckoning can be made for a vehicle equipped or not with ABS and with the load sensing valve in the semi trailers and in the tandem axle of the tractor. The spread sheet was applied in a example vehicle and the results are presented in this dissertation. The brakes system of this vehicle was optimized with the use of the spread sheet, showing as it can be of great assists the designer.
65

Structuration des mélanges ABS/PC en vue du recyclage des DEEE. / Structuration of ABS/PC morphology blends for recycling of WEEE.

Alkhuder, Aboubaker 18 December 2014 (has links)
La présence de matières plastiques dans les DEEE (déchets des équipements électriques et électroniques) a augmenté de 25% ces cinq dernières années. Avec la mise en place de nouvelles réglementations imposant des objectifs de recyclage élevés et l’augmentation des cours du pétrole, le recyclage des matières plastiques devient plus que jamais d’actualité. Dans ce contexte, tout en travaillant avec des polymères vierges, l’objectif de ce travail est de trouver une voie de valorisation des DEEE par le mélange de polymères. Le travail s’est focalisé sur l’amélioration des propriétés mécaniques des mélanges ABS/PC (70%/30% en masse) en structurant la morphologie de mélanges sous formes allongées (fibres et/ou lamelles). Pour ce faire, des outils spécifiques novateurs (éléments multiplicateurs de couches, filière de coextrusion fibrillaire) sont développés et utilisés. La démarche consiste à structurer d’abord des joncs, qui sont ensuite granulés, puis injectés lors d’une deuxième étape pour fabriquer des éprouvettes. Lorsque des morphologies allongées sont obtenues, des améliorations notables de propriétés (au choc en particulier) sont observées. Le travail termine par l’étude de l’effet sur la structuration et les propriétés finales d’un compatibilisant, l’ABS greffé anhydride maléique, synthétisé par extrusion réactive et rajouté au mélange ABS/PC. / Plastics in WEEE (Waste of Electric and Electronic Equipments) have increased up to 25% in the last five years. As new regulations are setting up increased recycling objectives and the oil prize is also increasing, plastic recycling is more than never an issue. In this context, while still working on virgin polymers, this work objective is to find a way to valorize the WEEE by the use of polymer blends. This work is focused on the upgrading of mechanical properties of ABS/PC (70%/30% wt%) blends by structuring the morphology of the blends creating elongated shapes (fibers and/or lamellas). To do so, innovative specific tools have been developed and used such as layer-multiplying mixing elements or fibrillar coextrusion dye. The first step of the procedure is to create structured strands of polymers which are then pelletized. Then these pellets are injected in a second step to create specimens. When elongated morphologies are obtained, significant improvements are observed in properties, especially for impact behavior. Finally, this work studies the effect of a compatibilizer on the structuration and the final properties of the blends. The compatibilizer, maleic anhydride grafted ABS, was synthesized through reactive extrusion and added in ABS/PC blends.
66

Structuration des mélanges ABS/PC en vue du recyclage des DEEE. / Structuration of ABS/PC morphology blends for recycling of WEEE.

Alkhuder, Aboubaker 18 December 2014 (has links)
La présence de matières plastiques dans les DEEE (déchets des équipements électriques et électroniques) a augmenté de 25% ces cinq dernières années. Avec la mise en place de nouvelles réglementations imposant des objectifs de recyclage élevés et l’augmentation des cours du pétrole, le recyclage des matières plastiques devient plus que jamais d’actualité. Dans ce contexte, tout en travaillant avec des polymères vierges, l’objectif de ce travail est de trouver une voie de valorisation des DEEE par le mélange de polymères. Le travail s’est focalisé sur l’amélioration des propriétés mécaniques des mélanges ABS/PC (70%/30% en masse) en structurant la morphologie de mélanges sous formes allongées (fibres et/ou lamelles). Pour ce faire, des outils spécifiques novateurs (éléments multiplicateurs de couches, filière de coextrusion fibrillaire) sont développés et utilisés. La démarche consiste à structurer d’abord des joncs, qui sont ensuite granulés, puis injectés lors d’une deuxième étape pour fabriquer des éprouvettes. Lorsque des morphologies allongées sont obtenues, des améliorations notables de propriétés (au choc en particulier) sont observées. Le travail termine par l’étude de l’effet sur la structuration et les propriétés finales d’un compatibilisant, l’ABS greffé anhydride maléique, synthétisé par extrusion réactive et rajouté au mélange ABS/PC. / Plastics in WEEE (Waste of Electric and Electronic Equipments) have increased up to 25% in the last five years. As new regulations are setting up increased recycling objectives and the oil prize is also increasing, plastic recycling is more than never an issue. In this context, while still working on virgin polymers, this work objective is to find a way to valorize the WEEE by the use of polymer blends. This work is focused on the upgrading of mechanical properties of ABS/PC (70%/30% wt%) blends by structuring the morphology of the blends creating elongated shapes (fibers and/or lamellas). To do so, innovative specific tools have been developed and used such as layer-multiplying mixing elements or fibrillar coextrusion dye. The first step of the procedure is to create structured strands of polymers which are then pelletized. Then these pellets are injected in a second step to create specimens. When elongated morphologies are obtained, significant improvements are observed in properties, especially for impact behavior. Finally, this work studies the effect of a compatibilizer on the structuration and the final properties of the blends. The compatibilizer, maleic anhydride grafted ABS, was synthesized through reactive extrusion and added in ABS/PC blends.
67

Estudo do desempenho na frenagem de um bi-trem com suspensão em \"tandem\" e com ABS / Braking performance of a bi-trem with tandem axle and ABS

Rafael Ferreira Polito 16 September 2005 (has links)
O bi-trem é um veículo cada vez mais comum no trânsito brasileiro. Por ser um veículo de grande porte, é capaz de se envolver em acidentes catastróficos caso o sistema de freio não esteja projetado de maneira adequada. Neste contexto é necessário um estudo que permita prever e otimizar o desempenho do sistema de freios para qualquer condição operacional. Para isso foi desenvolvida uma planilha de cálculos para estudar o desempenho da frenagem de um bi-trem. A planilha calcula a aderência que cada eixo utiliza, a desaceleração máxima desenvolvida pelo veículo, o espaço e o tempo de parada, a força de frenagem (e sua porcentagem) em cada eixo, a temperatura final do tambor, a eficiência do sistema de freios, as forças normais ao pavimento, a distribuição real e ideal das forças de frenagem e verifica se o cavalo mecânico e os semi-reboques se enquadram, respectivamente, nos diagramas 3 e 4 do anexo 10 da ECE-R13. Tais cálculos podem ser feitos com o veículo utilizando ou não ABS e com válvula sensível a carga nos semi-reboques e no \"tandem\" do cavalo mecânico. A planilha de cálculo foi aplicada em um veículo exemplo e os resultados são apresentados nesta dissertação. O sistema de freios desse veículo foi otimizado com a utilização da planilha, mostrando como ela pode ser de grande auxílio ao projetista. / The bi-trem (a vehicle similar to a twin trailler truck) is more and more common in the brazilians highways. Because it\'s a large and heavy vehicle it can cause catastrophics accidents if the brakes are not well developed. In this context it is necessary a study that allows to foresee and to optimize the performance of the brakes system for any operational condition. In this work an electronic spread sheet was developed in order to study the braking performance of a bi-trem. The spread sheet calcs the adhesion in each axle, the maximum deceleration, the braking space and the braking time, the braking force (and its percentage) in each axle, the final temperature of the drum, the brake system\'s efficiency, the normal forces, the actual and ideal brake force distribution, and verifies if the tractor and the semi trailers are fitted in the annex 10 of EGE-R13. The reckoning can be made for a vehicle equipped or not with ABS and with the load sensing valve in the semi trailers and in the tandem axle of the tractor. The spread sheet was applied in a example vehicle and the results are presented in this dissertation. The brakes system of this vehicle was optimized with the use of the spread sheet, showing as it can be of great assists the designer.
68

Návrh a zefektivnění parametrů FDM tisku / Design and efficiency of FDM printing parameters

Sysel, Karel January 2012 (has links)
The essence of the work is to test the possibilities specific type of simple 3D printing device, which has recently been getting more and more into the awareness of professionals and the general public. First, the work is focused on presentation 3D printing technology and current professional equipment, in the second part are experimentally evaluated possibilities of of a simple kind of 3D printers followed by assessment of the applicability of the device in engineering practice.
69

En studie av småhusentreprenader : Varför går det fel?

Abdul Hakim, Faisal, Said, Shazad January 2021 (has links)
Syftet med denna studie är att kartlägga småhusentreprenader och vilka problem samt konflikter som uppstår mellan entreprenader och beställare. Vidare är det tänkt att denna studie skulle ge allmänheten en bättre uppfattning kring varför konflikter uppstår mellan beställare och entreprenörer samt hur husleverantörer jobbar för att motverka dessa problem. För att uppnå syftet och besvara forskningsfrågorna användes en kvalitativ forskningsmetod i form av semistrukturerade intervjuer. Anledningen till att denna intervjuteknik tillämpades var för att ge respondenterna frihet att prata öppet om sina upplevelser och synpunkter. Respondenterna som intervjuades var fyra representanter för husleverantörer, tre beställare, en byggnadsinspektör och en kontrollansvarig. Resultatet av intervjuerna visade att det fanns en gemensam uppfattning bland beställare och husleverantörer kring att det är för mycket pappersarbete och att totalentreprenad är den mest optimala entreprenadformen för den som inte vill ta på sigallt för mycket ansvar. Det fanns dock även åsikter som skiljde sig. Studien visade att beställare upplever uppförandet av småhus som en långsam och energikrävande process. Problemen som är vanligt förekommande inom småhusentreprenader är att det finns en skillnad i språk och kunskap mellan parterna. Detta resulterar i att det blir en bristande kommunikation som i sin tur kan leda till diverse konflikter. Husleverantörerna är medvetna om dessa problem och jobbar kontinuerligt för att ta fram lösningar. En sådan lösning är att lägga stor vikt på dokumentation och kontrakt eftersom det är de som är lagligt bindande. Slutsatsen för denna studie var att en god kommunikation resulterar i färre missförstånd och konflikter. Konflikter går däremot inte att undvika helt, utan kommer alltid kunna uppstå på grund av mänskliga faktorer. / The purpose of this study was to investigate the single-family home construction industry and what problems arise. Furthermore, it was intended that this study would give the public a better idea of why conflicts arise between customers and contractors and how home suppliers work to counteract these problems. To achieve the purpose and get answers to the research questions, we used a qualitative research method in the form of semi-structured interviews. The reason why this interview technique was applied was to give respondents the freedom to talk openly about their experiences and views. The respondents interviewed were four representatives of house suppliers, three clients, a building inspector and an inspection manager. The results of the interviews showed that there was a common opinion among clients and house suppliers on certain issues, but then there were also opinions that differed. The study showed that customers experience the construction of detached houses as a slow and energy-intensive process. The problems that are common in detached house contracts are that there is a difference in language and knowledge between the involved parties. This results in a lack of communication which in turn can lead to various conflicts. Home suppliers are aware of the problems that exist in the industry and work continuously to develop solutions. One such solution is to place great emphasis on documentation and contracts because they are the ones that are legally binding. The conclusion of this study was that good communication results in fewer misunderstandings and conflicts. Conflicts, on the other hand, cannot be completely avoided, but will always arise due to human factors.
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On control and estimation problems in antilock braking systems / Quelques problèmes de commande et d'estimation liés aux systèmes d'antiblocage des roues

Aguado rojas, Missie María del Rocío 14 June 2019 (has links)
Cette thèse aborde trois problèmes liés à l’ABS dans le cadre de la dynamique de la roue : l’estimation de la rigidité de freinage étendue (XBS) des pneus lors du freinage d’urgence, la commande de l’ABS basée sur l’estimation de l’XBS, et l’estimation de la vitesse et de l’accélération angulaires de la roue à partir des mesures provenant d’un codeur avec des imperfections. L’objectif général de ce travail est de développer des outils visant à améliorer la performance des systèmes de freinage, en utilisant des techniques adaptées de l'automatique non linéaire. La première partie de la thèse est consacrée à la construction d’un observateur adaptatif commuté pour l’XBS, c’est-à-dire un observateur adaptatif dont les gains d’estimation commutent entre deux valeurs possibles en fonction du signe de la sortie mesurée du système. La stabilité de l’observateur est analysée en utilisant des outils pour des systèmes commutés et en cascade, ainsi que des concepts tels qu’excitation permanente et transformations singulières d’échelle de temps. La deuxième partie de la thèse est dédiée à la conception d’une loi de commande pour l’ABS. L’objectif de contrôle est formulé en termes de l’XBS et une loi de commande hybride est conçue afin de faire en sorte que les trajectoires du système satisfassent les conditions requises pour l’estimation de l’XBS. La stabilité du contrôleur est analysée en utilisant l'application de Poincaré. La troisième partie de la thèse aborde la construction d’un algorithme pour estimer la vitesse et l’accélération angulaires de la roue et éliminer des perturbations qui sont introduites par les imperfections du codeur, et dont l’amplitude et la fréquence sont une fonction de la position, la vitesse, et l’accélération angulaires (réelles) de la roue. L’algorithme est basé sur la méthode connue comme « time-stamping algorithm », ainsi que sur des techniques de filtrage est d’estimation de paramètres. Des essais expérimentaux et des simulations numériques illustrent la performance des algorithmes d’estimation et de contrôle présentés dans cette thèse. Dans tous les cas nos résultats sont comparés par rapport à l’état de l’art. / This thesis addresses three problems related to the antilock braking system (ABS) in the context of the wheel dynamics: the estimation of the tyre extended braking stiffness (XBS) during an emergency braking situation, the control of the ABS based on the estimation of the XBS, and the estimation of the angular velocity and acceleration of the wheel from the measurements of an incremental encoder with imperfections. The general objective of this work is to develop tools aimed at improving the performance of braking systems by using techniques adapted from nonlinear control theory. The first part of the manuscript is devoted to the construction of a switched adaptive observer for the XBS, that is, an adaptive observer whose estimation gains switch between two possible values based on the sign of the system’s measured output. The stability of the observer is analyzed using tools for switched and cascaded systems, as well as concepts such as persistency of excitation and singular time-scale transformations. The second part of the manuscript is dedicated to the design of a control algorithm for the ABS. The control objective is formulated in terms of the XBS and a hybrid controller is designed so that the trajectories of the system satisfy the conditions required for the estimation of the XBS. The stability of the controller is analyzed using the Poincaré map. The third part of the manuscript focuses on the construction of an algorithm to estimate angular velocity and acceleration of the wheel and remove perturbations which are introduced by the encoder imperfections and whose amplitude and frequency are a function of the wheel's (real) position, velocity, and acceleration. The algorithm is based on the method known as time-stamping algorithm, as well as filtering and parameter estimation techniques. Experimental tests and numerical simulations illustrate the performance of the estimation and control algorithms presented in this thesis. In all cases our results are compared with respect to the state of the art.

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