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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.
21

Mikroplastutsläpp från däckslitage : Ett rullande utsläpp / Release of microplastics from tyre wear : Rolling emissions

Agewall, John, Wallgren, Kim January 2019 (has links)
Antalet bilar har ökat stadigt genom åren och i mars 2019 befann sig nästan 4,9 miljoner personbilar i aktiv användning i Sverige. Något som inte får lika mycket uppmärksamhet som koldioxidutsläpp från trafiken och slitage av vägar är slitaget av bildäck. Regeringen har därmed tillsatt ett uppdrag där mängden mikroplastutsläpp ska kvantifieras, sprida kunskap om problemet och utveckla åtgärder mot utsläppen. En av myndigheterna som fått detta uppdrag är Statens väg- och transportforskningsinstitut (VTI), med vilka detta arbete genomfördes. Arbetet går ut på att försöka kvantifiera utsläppen av mikroplastutsläpp från personbilar samt undersöka vilka typer av slitage som är vanligast förekommande. Rapporten består av två delar, en litteraturstudie som ska ge en klar bild av nuläget, typer av däck, vad mikroplaster är samt varför slitage uppstår. Under den andra delen genomfördes mätningar på kasserade däck, där mönsterdjupsprofiler, vikt, mönsterdjup, DOT märkning, modell, märke, typ av däck och dimensioner antecknades. Med hjälp av profilerna och originaldata som tillhandahölls av olika däcktillverkare kunde de vanligaste slitagen bestämmas och den bortslitna vikten och volymen kunde uppskattas. De vanligaste typerna av slitage är centrum-, jämnt- och sidoslitage, vilket beror på för högt lufttryck i däcken, samt fel hjulinställningar. Den totala årliga mängden utsläpp av mikroplaster från personbilar uppskattades ligga mellan 8 300 och 16 700 ton. / The number of cars has been on a steady increase in Sweden and in mars 2019 there were almost 4,9 million cars in active use. Nowadays most of the attention is focused on pollution through carbon dioxide and the wear of roads. However, a problem that often goes unrecognized is the tear of car tyres and the release of microplastics into the environment. In order to quantify the amount of microplastics released into the environment, the Swedish government has instructed The Swedish National Road and Transport Research Institute (VTI) to carry through with this. The aim of this report is to, with the help of VTI, try to quantify the amount of microplastics released from private car traffic and examine the main types of tyre wear. This report consists of two parts, one study of what microplastics is and how tyre wear arises. The second part consists of measuring, where used tyres have had their weight and tread measured. The profile of the tear, DOT number, production date, model, dimensions and type of tyre is additional data that was collected. Through the use of data provided by the tyre companies and the collected data, the total loss of weight and volume together with a yearly weight and volume loss could be calculated. Through analysis of the tyre profiles and their tread depths the most occurring type of wear patterns was determined, which were central, even and side wear. The estimated yearly amount of microplastics released in Sweden was between 8 300 and 16 700 tonnes.
22

Measuring the Mechanical Properties of Bicycle Tyres to Help Predict and Minimize Wobble for Enhanced Safety

Dressel, Andrew E., Moore, Jason K. 03 January 2023 (has links)
Wobble, also known as speed wobble or shimmy, and the hazard it can cause to cyclists, is a well-known behavior of some bicycles. lt is a relatively high-frequency oscillation, 4-10 Hz. of the front fork and wheel assembly about the steering axis, and it can result in loss of control if left unaddressed. The importance of tyre mechanical properties, specifically conering stiffness, to the wobble motion of bicycles has been shown. Some tyres can make a bicycle more likely to wobble, while others can make the same bicycle less likely to wobble. There are only a few facilities in the world, however, capable of measuring these properties of bicycle tyres, and facilities for testing motorcycle and automobile tyres are not designed to work with bicycle wheels and/or are prohibitively expensive to use. We introduce and characterize an inexpensive, table-top device for measuring the necessary mechanical properties of bicycle tyres.
23

Vliv defektu pneumatiky na jízdní dynamiku vozidla / Influence of Tyre Defect on the Driving Dynamics of a Vehicle

Kubík, Adam January 2014 (has links)
In this thesis, an effect of a tyre defect on the driving dynamics of a vehicle is dealt with. The first part of the thesis is mainly concerned with the vehicle dynamics, road resistance, adhesion, orientation characteristics of the tyres and slowing down. This chapter is followed by an overview of the manufacturing process and construction of modern passenger car tyres. The practical part is focused on driving tests that are used to demonstrate the influence of tyre defects on handling characteristics of the vehicle. The main focus of this thesis is on directional variation, braking distance, deceleration and lateral acceleration. The very end of the thesis concentrates on tyre defect in higher speeds and its after-effects as well as precautions for mitigation of these after-effects.
24

Acoustic and thermal properties of recycled porous media

Mahasaranon, Sararat January 2011 (has links)
This thesis is concerned with developing porous materials from tyre shred residue and polyurethane binder for acoustic absorption and thermal insulation applications. The resultant materials contains a high proportion of open, interconnected cells that are able to absorb incident sound waves through viscous friction, inertia effects and thermal energy exchanges. The materials developed are also able to insulate against heat by suppressing the convection of heat and reduced conductivity of the fluid locked in the large proportion of close-cell pores. The acoustic absorption performance of a porous media is controlled by the number of open cells and pore size distribution. Therefore, this work also investigates the use of catalysts and surfactants to modify the pore structure and studies the influence of the various components in the chemical formulations used to produce these porous materials. An optimum type and amounts of catalyst are selected to obtain a high chemical conversion and a short expanding time for the bubble growth phase. The surfactant is used to reduce the surface tension and achieve a homogenous mixing between the solid particulates tyre shred residue, the water, the catalyst and the binder. It is found that all of the components significantly affect the resultant materials structure and its morphology. The results show that the catalyst has a particularly strong effect on the pore structure and the ensuing thermal and acoustical properties. In this research, the properties of the porous materials developed are characterized using standard experimental techniques and the acoustic and thermal insulation performance underpinned using theoretical models. The important observation from this research is that a new class of recycled materials with pore stratification has been developed. It is shown that the pore stratification can have a positive effect on the acoustic absorption in a broadband frequency range. The control of reaction time in the foaming process is a key function that leads to a gradual change in the pore size distribution, porosity, flow resistivity and tortuosity which vary as a function of sample depth. It is shown that the Pade approximation is a suitable model to study the acoustic behaviour of these materials. A good agreement between the measured data and the model was attained.
25

Multibody model vozidla - hodnocení jízdního komfortu / Vehicle Multibody Model - Ride Comfort Evaluation

Friedl, Michal Unknown Date (has links)
This master’s thesis is concerned of ride comfort. It uses MBS simulation software MSC Adams, especially its Car module. It contains simulations of ride over the road with obstacles that represent the everyday conditions in real traffic. The main area of focus is to find acceleration data that are present on the driver’s seat and co-driver’s seat in relation on specific suspension settings which affect the ride comfort.
26

Redesign of a tribological pin-on-disc machine / Omkonstruktion av en tribologisk pin-on-disc-maskin

Szumin, Michal January 2022 (has links)
In contradistinction with road transport exhaust particulate matter (PM) emission, non-exhaust PM emission has not decreased substantially in recent years. One source of non-exhaust PM emission is studded tyre-pavement contact. A-state-of-the-art experimental machines must be developed and improved in order to make a contribution to decrease of non-exhaust PM emission consequently improving human health. This thesis carried out at the department of Machine Design at KTH Royal Institute of Technology deals with redesign of the tribometer available at the department premises to mount and test scaled down studded tyre-pavement PM generation. Three concepts of redesigned tribometer were generated and evaluated against each other, out of which one was selected to be designed in detail, manufactured, assembled and tested. Final concept validation was conduction of an experiment with studded and plain tyres running on a granite sample. PM10 and PM0.5 results were collected and analysed and final redesign of the tribometer was assessed. / I motsats till utsläpp av partiklar från vägtransporter har utsläpp av partiklar från andra källor än avgaser inte minskat avsevärt under de senaste åren. En källa till utsläpp av partiklar utöver avgaser är kontakten mellan dubbdäck och vägbana. Det är nödvändigt att utveckla och förbättra de senaste laborationsmaskinerna för att kunna bidra till att minska icke avgasrelaterade utsläpp och därmed människors hälsa. Denna avhandling, som utförts vid avdelningen för maskinkonstruktion vid KTH (Kungliga Tekniska Högskolan), handlar om att omkonstruera den tribometer som finns tillgänglig vid institutionen för att kunna montera och testa en nedskalad produktion av partiklar från däck och beläggning med dubbdäck. Tre koncept för en omkonstruerad tribometer skapades och utvärderades mot varandra, varav en valdes ut för att konstrueras i detalj, tillverkas, monteras och testas. Den slutliga valideringen av konceptet bestod av att genomföra ett experiment med dubbade och vanliga däck som kördes på ett granitprov. PM10- och PM0.5-resultaten samlades in och analyserades, varpå den slutliga omkonstruktionen av tribometern utvärderades.
27

Acoustic and Thermal Properties of Recycled Porous Media

Mahasaranon, Sararat January 2011 (has links)
This thesis is concerned with developing porous materials from tyre shred residue and polyurethane binder for acoustic absorption and thermal insulation applications. The resultant materials contains a high proportion of open, interconnected cells that are able to absorb incident sound waves through viscous friction, inertia effects and thermal energy exchanges. The materials developed are also able to insulate against heat by suppressing the convection of heat and reduced conductivity of the fluid locked in the large proportion of close-cell pores. The acoustic absorption performance of a porous media is controlled by the number of open cells and pore size distribution. Therefore, this work also investigates the use of catalysts and surfactants to modify the pore structure and studies the influence of the various components in the chemical formulations used to produce these porous materials. An optimum type and amounts of catalyst are selected to obtain a high chemical conversion and a short expanding time for the bubble growth phase. The surfactant is used to reduce the surface tension and achieve a homogenous mixing between the solid particulates tyre shred residue, the water, the catalyst and the binder. It is found that all of the components significantly affect the resultant materials structure and its morphology. The results show that the catalyst has a particularly strong effect on the pore structure and the ensuing thermal and acoustical properties. In this research, the properties of the porous materials developed are characterized using standard experimental techniques and the acoustic and thermal insulation performance underpinned using theoretical models. The important observation from this research is that a new class of recycled materials with pore stratification has been developed. It is shown that the pore stratification can have a positive effect on the acoustic absorption in a broadband frequency range. The control of reaction time in the foaming process is a key function that leads to a gradual change in the pore size distribution, porosity, flow resistivity and tortuosity which vary as a function of sample depth. It is shown that the Pade approximation is a suitable model to study the acoustic behaviour of these materials. A good agreement between the measured data and the model was attained. / Ministry of Science and Technology of Thailand; Naresuan University, Phitsanulok, Thailand,
28

Política externa e democracia: reflexões sobre o acesso à informação na política externa brasileira a partir da inserção da temática ambiental no caso dos pneus entre o Mercosul e a OMC / Foreign Policy and Democracy: access to information in Brazilian foreign policy since the introduction of environmenal arguments in the Retreaded Tyres case from Mercosur to the WTO

Specie, Priscila 04 August 2008 (has links)
Esse trabalho explora a relação entre política externa e democracia a partir das reflexões sobre o acesso à informação na política externa brasileira com a inserção da temática ambiental no caso dos pneus, entre a controvérsia do Mercosul e o contencioso da OMC. Por meio de uma aproximação entre o instrumental teórico de análise de política externa e de políticas públicas foi possível questionar os limites do acesso à informação como condição para a participação de outros atores além do Ministério de Relações Exteriores (MRE) na redefinição da defesa do Brasil, com a inserção da temática ambiental, de uma instância para outra. A hipótese demonstrada refere-se à ampliação do acesso à informação que seguiu a ampliação dos espaços de definição da política externa no caso. Essa ampliação foi observada a partir do processo de descentralização dos espaços tradicionais de definição da política externa brasileira (MRE), com a inclusão, por exemplo, do Ministério do Meio Ambiente. No entanto, a tendência de ampliação do acesso à informação como condição para a participação de atores não governamentais, neste caso, mostrou-se limitada por uma conduta seletiva e informal pelos órgãos do governo para interlocução com determinados atores / This research aims at studying the relationship between foreign policy and democracy. The study focuses on access to information in Brazilian foreign policy through the introduction of the environmental arguments in the retreaded tyres dispute from Mercosur to the WTO (WT/DS332). The research was based on foreign and public policy analysis. These theoretical bases enabled to investigate the limits to a wider participation of actors other than the Ministry of Foreign Affairs (MRE) on foreign policy. The research shows an enlargement on policy making with the integration of the environmental arguments which resulted, for instance, in the participation of the Ministry of the Environment. Subsequently, it was possible to notice a wider access to information to a whole new range of actors, including non state actors. Nevertheless, in the present case study the tendency to a democratic access to information found its limits on the selective and informal conduct of the MRE to interact with certain actors in certain circunstances
29

Política externa e democracia: reflexões sobre o acesso à informação na política externa brasileira a partir da inserção da temática ambiental no caso dos pneus entre o Mercosul e a OMC / Foreign Policy and Democracy: access to information in Brazilian foreign policy since the introduction of environmenal arguments in the Retreaded Tyres case from Mercosur to the WTO

Priscila Specie 04 August 2008 (has links)
Esse trabalho explora a relação entre política externa e democracia a partir das reflexões sobre o acesso à informação na política externa brasileira com a inserção da temática ambiental no caso dos pneus, entre a controvérsia do Mercosul e o contencioso da OMC. Por meio de uma aproximação entre o instrumental teórico de análise de política externa e de políticas públicas foi possível questionar os limites do acesso à informação como condição para a participação de outros atores além do Ministério de Relações Exteriores (MRE) na redefinição da defesa do Brasil, com a inserção da temática ambiental, de uma instância para outra. A hipótese demonstrada refere-se à ampliação do acesso à informação que seguiu a ampliação dos espaços de definição da política externa no caso. Essa ampliação foi observada a partir do processo de descentralização dos espaços tradicionais de definição da política externa brasileira (MRE), com a inclusão, por exemplo, do Ministério do Meio Ambiente. No entanto, a tendência de ampliação do acesso à informação como condição para a participação de atores não governamentais, neste caso, mostrou-se limitada por uma conduta seletiva e informal pelos órgãos do governo para interlocução com determinados atores / This research aims at studying the relationship between foreign policy and democracy. The study focuses on access to information in Brazilian foreign policy through the introduction of the environmental arguments in the retreaded tyres dispute from Mercosur to the WTO (WT/DS332). The research was based on foreign and public policy analysis. These theoretical bases enabled to investigate the limits to a wider participation of actors other than the Ministry of Foreign Affairs (MRE) on foreign policy. The research shows an enlargement on policy making with the integration of the environmental arguments which resulted, for instance, in the participation of the Ministry of the Environment. Subsequently, it was possible to notice a wider access to information to a whole new range of actors, including non state actors. Nevertheless, in the present case study the tendency to a democratic access to information found its limits on the selective and informal conduct of the MRE to interact with certain actors in certain circunstances
30

Neuartige Warmmahltechnologie zum Recycling von Elastomeren und Analyse prozessbedingter Eigenschaften / Novel milling technology for the recycling of elastomers and analysis of process-related properties

Hoyer, Stefan 15 February 2018 (has links) (PDF)
Die Arbeit widmet sich der Problemstellung der Substitution des Primärrohstoffes Kautschuk durch Rezyklate in Form von Gummimehl. Die für das innerbetriebliche Recycling von Kleinchargen technischer Elastomere hier eigens konzipierte und umgesetzte Warmmahltechnologie dient zur Herstellung von Gummimehlrezyklat hoher Qualität aus Lkw-Altreifen. Hinsichtlich ausgewählter Verarbeitungs- und Materialkennwerte von Mischung und Vulkanisat werden die Auswirkungen der Zugabe von Rezyklaten und die wesentlichen Einflussgrößen des den Rezyklaten zugrunde liegenden Aufbereitungsprozesses – das Kryogenmahlverfahren bzw. die neu entwickelte Warmmahltechnologie – herausgearbeitet. Abschließend erfolgt die Formulierung materialspezifischer Versagensmechanismen, die das entsprechende Aufbereitungsverfahren der Rezyklate berücksichtigen. / The work is devoted to the problem of the substitution of the primary raw material rubber by recycled materials in the form of rubber powders. For the in-plant recycling of small batches of technical elastomers an ambient grind technology was specifically designed and implemented for making rubber powders of high quality out of used truck tires. In terms of selected processing and material characteristics of the mixture and the vulcanizate the influences of the addition of recycled material and the significant factors affecting the regeneration process underlying these recyclates – the cryogenic grinding versus the new developed ambient grinding technology – were worked out. Finally, the material-specific failure mechanisms were formulated, incorporating the regeneration process of such regenerated materials.

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