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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

Hydraulický okruh pojezdu dvoucestného vozidla / Hydraulic circle of undercarriage two-way vehicle

Rozumek, Jaroslav January 2008 (has links)
The aim of this diploma thesis is a concept of hydraulic (hydrostatic) circuit of rail – road vehicle drive for the drive on communication and railway. As my work is not related to a specific type of road vehicle dedicated to a drive on railway, my work is of strictly reference nature. On request I was provided by Bosh Rexroth s.r.o. with a hydraulic scheme of two-way undercarriage (see appendix), which is also a source material for the new concept. My work is focused on interests of SaZ s.r.o., which deals with the development and rebuilding of road vehicles into rail – road vehicles. The first phase is focused on the choice of the most convenient component of railway undercarriage in accord with the assignment. The second phase is oriented on the calculation of travel parameters, dimensioning of systems with concretization of typal mark of components. A part of the second phase is also a concept of hydraulic braking system of rail undercarriage. After that follows a complete evaluation, eventually an alternative solution of given problem.
22

Analysis of Erosion Rates on User-Created Off-Road Vehicle Trails inSoutheastern Ohio

Wagner, Richard R. 16 September 2022 (has links)
No description available.
23

Identification de sources acoustiques au passage d'un véhicule routier par imagerie acoustique parcimonieuse dans le domaine temporel / Identification of acoustic sources in a road vehicle pass-by situation with a sparse time-domain acoustic imaging method

Cousson, Rémi 14 December 2018 (has links)
Le présent travail de recherche s'inscrit dans le cadre de la caractérisation de l'émission de bruit des véhicules routiers. On désire identifier les sources de bruit d'un véhicule en mouvement, lors de son passage sur une voie de circulation en conditions réelles, à partir de mesures acoustiques effectuées à poste fixe en bord de voie. Les méthodes d'imagerie acoustique utilisées actuellement présentent des performances insuffisantes sur véhicules routiers. Un état de l'art a permis d’identifier une méthode existante, MSA-PSF, consistant à effectuer sous certaines hypothèses une déconvolution sur sources mobiles dans le domaine fréquentiel, et originellement utilisée en aéronautique. Cette méthode est ici adaptée au contexte des véhicules routiers. Dans un deuxième temps, une approche originale est introduite pour répondre spécifiquement aux contraintes de ce contexte : CLEANT. Il s’agit d’une méthode itérative, dans le domaine temporel avec une approche large bande, qui prend en compte les effets du déplacement des sources et qui comporte deux paramètres permettant d’affiner les résultats : le facteur de boucle et le critère d’arrêt. Une version filtrée en fréquence est également proposée et montre une amélioration de l’identification de sources secondaires dans certains cas. CLEANT présente l’avantage d’obtenir des signaux-sources temporels reconstruits, ouvrant la voie à d’autres analyses, en particulier l’utilisation de la cohérence avec des signaux issus de mesures embarquées pour la séparation des contributions de sources décorrélées. MSA-PSF et CLEANT sont évaluées sur des simulations numériques à l'aide d'indicateurs mesurant leurs performances sur les aspects localisation et quantification de sources. Elles sont par la suite testées expérimentalement en conditions contrôlées de laboratoire, par l'utilisation d'une source mobile. Cette expérience permet une première application à un cas pratique, impliquant un mouvement linéaire, la présence de deux sources simultanées et des signaux de différentes natures (tonale et large bande). Enfin, elles sont comparées à l’approche classique de formation de voies sur source mobile, dans le cadre d’une expérience avec véhicule en conditions réelles. L'approche originale CLEANT fournit des résultats très encourageants, représentant une amélioration de la formation de voies classique, notamment en basse fréquence sur les cas testés. L'application à un véhicule en conditions réelles illustre certains comportements potentiellement problématiques de CLEANT et les solutions apportées par sa version filtrée en fréquence ou par l'ajustement de ses différents paramètres. Un premier test des approches par référencement avec des signaux issus de mesures embarquées est également présenté pour discriminer l'origine physique des sources, et souligne l'incidence de la brièveté des signaux inhérente au contexte de sources au passage. / The study detailed in this manuscript is part of the effort to characterize the noise emission from road vehicles. We wish to identify the noise sources of a moving vehicle, when driven on a roadway in real-world conditions, with roadside acoustic measurements. The current acoustic imaging methods do not provide sufficient performance on road vehicles. A state of the art led to the selection of an existing method, MSA-PSF, which consists in deconvolving signals from mobile sources in the frequency domain under certain assumptions, and was originally developed for aeroacoustics. This method is adapted here to the context of road vehicles. Then, an original approach is proposed in order to tackle the specific constraints of this context: CLEANT. This is an iterative method, performed in time domain with a wideband approach, which takes into account the effect of sources motion and includes two parameters designed to refine the result: the loop factor and the stopping criterium. A further version of the algorithm, including a frequency filter, is also proposed and shows significant improvement in identifying secondary sources in some particular cases. An interesting point of CLEANT is the availability of the sources reconstructed time signals, which enables other types of analysis, especially the use of the coherence with signals from on-board measurements in order to separate the contributions of uncorrelated sources. MSA-PSF and CLEANT are evaluated with numerical simulations and a set of indicators to measure their source localization and quantification performance. They are then tested in a controlled laboratory conditions experiment, using a moving source. This experiment represents a first application of the methods to a practical case, involving a linear motion, two simultaneous sources and different kinds of signals (tone and wideband). They are finally compared to the classical approach of moving source beamforming, within the frame of an experiment on a road vehicle, in real-world conditions. The original approach CLEANT yields very encouraging results, and is a clear improvement from the conventional beamforming, especially at low frequency for the tested cases. Applying it to a road vehicle in real-world conditions highlights a potentially troublesome behavior of the method, and the solution brought by CLEANT's frequency filtered version, or by adapting its various parameters. The coherence with reference signals to discriminate the physical origins of the sources is also tested and underlines the role of the short duration of the signals related to the sources passing-by context.
24

Estudo de desempenho de autoveículos rodoviários considerando o passeio do centro de gravidade e restrições impostas pelo binômio pneumático x pavimento / not available

Canale, Antonio Carlos 22 November 1991 (has links)
Este trabalho aplica um procedimento para análise do desempenho de um autoveículo rodoviário (Kadett GS 2.0 da General Motors do Brasil), em aceleração e desaceleração (freagem), considerando o \"passeio do centro de gravidade\" e as \"restrições impostas pelo binômio pneumático x pavimento\". A dinâmica do processo de frenagem do veículo/exemplo é estudada, obtendo-se a desaceleração e o espaço percorrido, como função do \"passeio do centro de gravidade\" e duas \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são realizadas. Para o controle do processo de frenagem do veículo/exemplo, obtém-se uma \"função-transferência\" que muda continuamente o balanceamento das forças de frenagem nos eixos, utilizando-se, para isto, de sinais oriundos de um acelerômetro e de um sensor de peso instalados no veículo. Esta função otimiza o processo de frenagem para qualquer carregamento permissível do veículo e em qualquer nível de desaceleração (qualquer tipo de piso). Deste veículo obtêm-se os diagramas de rendimento, aceleração líquida para cada marcha engrenada, e, posteriormente, o \"tempo de aceleração\" e \"retomada de velocidade\", como função do \"passeio do centro de gravidade\" e das \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são também realizadas. Em todos os casos, foram obtidos bons resultados na comparação teórico-experimental, validando o modelo matemático elaborado e o procedimento de análise. / This work applies a procedure for the analysis of the performance of a road vehicle, (General Motors do Brasil, Kadett GS 2.0), in acceleration and deceleration (braking), which takes into consideration the centre of gravity envelope and the restrictions imposed by the tyre/surface relationship. A study is made of the dynamic braking process of the vehicle/example, and the deceleration and distance covered are obtained as a functions of the c.g. position and the tyre/surface relationship. Comparisons are made between theory and experiment. A transfer function is obtained for the control of the braking process of the vehicle/example, that continually changes the balance of the braking forces on the axles, thorugh the use of signals transmitted from an accelerometer (g - meter) and a sensor giving the installed weight of the vehicle. This function optimizes the braking process for any permissible vehicle load and deceleration level, for any type of surface. The performance diagrams, the acceleration in each gear, and, following these the acceleration time and time-to-return-to-normal-speed are obtained as functions of the position of the c.g. and the restrictions imposed by the tyre/surface relationship. Comparisons of theory with practice are also made. In all cases, comparisons between theory and practice give good results, validating the mathematical model and the analysis procedure.
25

Suspension design for off-road construction machines

Rehnberg, Adam January 2011 (has links)
Construction machines, also referred to as engineering vehicles or earth movers, are used in a variety of tasks related to infrastructure development and material handling. While modern construction machines represent a high level of sophistication in several areas, their suspension systems are generally rudimentary or even nonexistent. This leads to unacceptably high vibration levels for the operator, particularly when considering front loaders and dump trucks, which regularly traverse longer distances at reasonably high velocities. To meet future demands on operator comfort and high speed capacity, more refined wheel suspensions will have to be developed. The aim of this thesis is therefore to investigate which factors need to be considered in the fundamental design of suspension systems for wheeled construction machines. The ride dynamics of wheeled construction machines are affected by a number of particular properties specific to this type of vehicle. The pitch inertia is typically high in relation to the mass and wheelbase, which leads to pronounced pitching. The axle loads differ considerably between the loaded and the unloaded condition, necessitating ride height control, and hence the suspension properties may be altered as the vehicle is loaded. Furthermore, the low vertical stiffness of off-road tyres means that changes in the tyre properties will have a large impact on the dynamics of the suspended mass. The impact of these factors has been investigated using analytical models and parameters for a typical wheel loader. Multibody dynamic simulations have also been used to study the effects of suspended axles on the vehicle ride vibrations in more detail. The simulation model has also been compared to measurements performed on a prototype wheel loader with suspended axles. For reasons of manoeuvrability and robustness, many construction machines use articulated frame steering. The dynamic behaviour of articulated vehicles has therefore been examined here, focusing on lateral instabilities in the form of “snaking” and “folding”. A multibody dynamics model has been used to investigate how suspended axles influence the snaking stability of an articulated wheel loader. A remote-controlled, articulated test vehicle in model-scale has also been developed to enable safe and inexpensive practical experiments. The test vehicle is used to study the influence of several vehicle parameters on snaking stability, including suspension, drive configuration and mass distribution. Comparisons are also made with predictions using a simplified linear model. Off-road tyres represent a further complication of construction machine dynamics, since the tyres’ behaviour is typically highly nonlinear and difficult to evaluate in testing due to the size of the tyres. A rolling test rig for large tyres has here been evaluated, showing that the test rig is capable of producing useful data for validating tyre simulation models of varying complexity. The theoretical and experimental studies presented in this thesis contribute to the deeper understanding of a number of aspects of the dynamic behaviour of construction machines. This work therefore provides a basis for the continued development of wheel suspensions for such vehicles. / QC 20110531
26

Estudo de desempenho de autoveículos rodoviários considerando o passeio do centro de gravidade e restrições impostas pelo binômio pneumático x pavimento / not available

Antonio Carlos Canale 22 November 1991 (has links)
Este trabalho aplica um procedimento para análise do desempenho de um autoveículo rodoviário (Kadett GS 2.0 da General Motors do Brasil), em aceleração e desaceleração (freagem), considerando o \"passeio do centro de gravidade\" e as \"restrições impostas pelo binômio pneumático x pavimento\". A dinâmica do processo de frenagem do veículo/exemplo é estudada, obtendo-se a desaceleração e o espaço percorrido, como função do \"passeio do centro de gravidade\" e duas \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são realizadas. Para o controle do processo de frenagem do veículo/exemplo, obtém-se uma \"função-transferência\" que muda continuamente o balanceamento das forças de frenagem nos eixos, utilizando-se, para isto, de sinais oriundos de um acelerômetro e de um sensor de peso instalados no veículo. Esta função otimiza o processo de frenagem para qualquer carregamento permissível do veículo e em qualquer nível de desaceleração (qualquer tipo de piso). Deste veículo obtêm-se os diagramas de rendimento, aceleração líquida para cada marcha engrenada, e, posteriormente, o \"tempo de aceleração\" e \"retomada de velocidade\", como função do \"passeio do centro de gravidade\" e das \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são também realizadas. Em todos os casos, foram obtidos bons resultados na comparação teórico-experimental, validando o modelo matemático elaborado e o procedimento de análise. / This work applies a procedure for the analysis of the performance of a road vehicle, (General Motors do Brasil, Kadett GS 2.0), in acceleration and deceleration (braking), which takes into consideration the centre of gravity envelope and the restrictions imposed by the tyre/surface relationship. A study is made of the dynamic braking process of the vehicle/example, and the deceleration and distance covered are obtained as a functions of the c.g. position and the tyre/surface relationship. Comparisons are made between theory and experiment. A transfer function is obtained for the control of the braking process of the vehicle/example, that continually changes the balance of the braking forces on the axles, thorugh the use of signals transmitted from an accelerometer (g - meter) and a sensor giving the installed weight of the vehicle. This function optimizes the braking process for any permissible vehicle load and deceleration level, for any type of surface. The performance diagrams, the acceleration in each gear, and, following these the acceleration time and time-to-return-to-normal-speed are obtained as functions of the position of the c.g. and the restrictions imposed by the tyre/surface relationship. Comparisons of theory with practice are also made. In all cases, comparisons between theory and practice give good results, validating the mathematical model and the analysis procedure.
27

Studie příčného rychlostního pole v blízkosti rotujícího kola s uvažováním vlivu nucené konvekce kotoučové brzdy / Study of transverse velocity field in the vicinity of rotating wheel with assumption of forced convection of disc brake

Regner, Dominik January 2019 (has links)
The master thesis deals with the influence of a local change of temperature due to advection from disc brake to axial velocity field close to the rotating wheel of a car. The second goal is to set parameters applicable to various wheel discs and study of the influence of these parameters to aerodynamical properties of car and thermodynamical properties of the disc brake. The thesis is numerically executed in StarCCM+. The first part focuses on theoretical background about the numerical solution and current status of research. There are described disc parameters, geometry input and solver settings in the second part. The final part deals with a comparison of velocity fields for isothermal and thermodynamical model and evaluates the influence of parameters to velocity field, aerodynamical drag and thermodynamical performance of the brake.
28

Etude expérimentale de la dispersion de particules ultrafines dans le sillage de modèles simplifiés de véhicules automobiles / Experimental study of ultrafine particle dispersion in the wake of road vehicle models

Rodriguez, Romain 22 October 2018 (has links)
La pollution de l’air cause de près de 7 millions de décès annuels dans le monde. L’exposition aux Particules Ultrafines (PUF), polluants parmi les plus néfastes pour la santé, atteint ses niveaux les plus importants en milieu urbain, principalement dus au transport routier. Dans cette thèse, nous examinons les liens entre les champs de concentration en nombre des PUF émises à l'échappement dans le sillage de modèles simplifiés d'automobiles (corps d’Ahmed) et les propriétés de ces écoulements. Ces travaux permettent de mieux comprendre les niveaux d'exposition aux PUF auxquels sont soumis tous les usagers de la route à l’échelle du sillage du véhicule. Trois modèles simplifiés de véhicules ont été utilisés. Ils sont caractérisés par leur angle de lunette arrière permettant de reproduire en soufflerie les structures principales des écoulements de sillage automobile. A l’aide d’une méthode innovante de traitement des données, des mesures de vitesses acquises grâce à des techniques différentes (LDV/PIV) ont été analysées. Elles ont révélé que l’angle d’inclinaison de la lunette a un rôle déterminant sur la structure des écoulements de sillage. Par ailleurs, la comparaison avec les mesures des concentrations en nombre de PUF a permis de montrer que le volume de la structure torique de recirculation en proche culot, dépendant de la géométrie, a un impact majeur sur la dispersion des particules dans la direction verticale. Enfin, il est mis en évidence que les structures tourbillonnaires longitudinales existantes pour une inclinaison intermédiaire de la lunette ont un impact prépondérant sur la dispersion transversale ainsi que sur la symétrie des champs de concentration. / Around 7 million worldwide annual death sare due to air pollution. Among all pollutants, UltrafineParticles (UFP) cause strong adverse effects. Due to road transport, UFP exposure reaches its most significant levels in urban areas. In this thesis, the aim is to assess the links between the wake flow properties of simplified car models(Ahmed bodies) and UFP number concentration fields due to exhaust emission. This study enables the knowledge about UFP exposure levels of all road users at vehicle wake scale to be better understood. Three simplified car models with three corresponding rear slant angles have been used in order to reproduce the principal wake structures of road vehicles in a wind tunnel. Thanks to an innovative data processing method, velocity measurements with two techniques(LDV/PIV) point out the major role of the rear slantangle on the model wake structures. Moreover, comparisons have been made with particle number concentration measurements of UFP in the wake of the same models. We highlighted the link between the volume of the toric recirculation region close to the rear and the vertical dispersion of UFP. Furthermore, longitudinal vortices that exist with the intermediate rear slant angle geometry play an important role on the transversal dispersion as well as on the concentration field symetry.
29

Eismo dalyvių kelyje atpažinimas naudojant dirbtinius neuroninius tinklus ir grafikos procesorių / On - road vehicle recognition using neural networks and graphics processing unit

Kinderis, Povilas 27 June 2014 (has links)
Kasmet daugybė žmonių būna sužalojami autoįvykiuose, iš kurių dalis sužalojimų būna rimti arba pasibaigia mirtimi. Dedama vis daugiau pastangų kuriant įvairias sistemas, kurios padėtų mažinti nelaimių skaičių kelyje. Tokios sistemos gebėtų perspėti vairuotojus apie galimus pavojus, atpažindamos eismo dalyvius ir sekdamos jų padėtį kelyje. Eismo dalyvių kelyje atpažinimas iš vaizdo yra pakankamai sudėtinga, daug skaičiavimų reikalaujanti problema. Šiame darbe šiai problemai spręsti pasitelkti stereo vaizdai, nesugretinamumo žemėlapis bei konvoliuciniai neuroniniai tinklai. Konvoliuciniai neuroniniai tinklai reikalauja daug skaičiavimų, todėl jie optimizuoti pasitelkus grafikos procesorių ir OpenCL. Gautas iki 33,4% spartos pagerėjimas lyginant su centriniu procesoriumi. Stereo vaizdai ir nesugretinamumo žemėlapis leidžia atmesti didelius kadro regionus, kurių nereikia klasifikuoti su konvoliuciniu neuroniniu tinklu. Priklausomai nuo scenos vaizde, reikalingų klasifikavimo operacijų skaičius sumažėja vidutiniškai apie 70-95% ir tai leidžia kadrą apdoroti atitinkamai greičiau. / Many people are injured during auto accidents each year, some injures are serious or end in death. Many efforts are being put in developing various systems, which could help to reduce accidents on the road. Such systems could warn drivers of a potential danger, while recognizing on-road vehicles and tracking their position on the road. On-road vehicle recognition on image is a complex and computationally very intensive problem. In this paper, to solve this problem, stereo images, disparity map and convolutional neural networks are used. Convolutional neural networks are very computational intensive, so to optimize it GPU and OpenCL are used. 33.4% speed improvement was achieved compared to the central processor. Stereo images and disparity map allows to discard large areas of the image, which are not needed to be classified using convolutional neural networks. Depending on the scene of the image, the number of the required classification operations decreases on average by 70-95% and this allows to process the image accordingly faster.
30

Zařízení pro měření výškové polohy těžiště vozidla / Device for measuring the centre of gravity height position of road vehicle

Kubica, Petr January 2015 (has links)
This diploma thesis deals the with measurment of the centre of gravity height position of a road vehicle and its issues. The introduction of this thesis focuses on the determining of the position of the center of gravity and the moment of inertia of a road vehicle. The next part is about creationing of a construction plan and its verification. The thesis contains a sensitivity analysis of this device including its results. The end of the thesis informs about the executed measurment in a laboratory and about recommendations for next measurments.

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