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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.
131

Analysis of Vehicle Dynamics and Control of Occupant Biodynamics using a Novel Multi-Occupant Vehicle Model

Joshi, Divyanshu January 2016 (has links)
Due to the detrimental effects of ride vibrations on occupants and increasing safety concerns, improvement in vehicle dynamic characteristics has become a key focus of researchers. Typically, ride and handling problems have been dealt with independently. There is a dearth of vehicle models capable of capturing occupant biodynamics and its implication on vehicle ride and handling. Also in general, the objective of conventional control systems has been to attenuate vertical dynamic response of the sprung mass of a vehicle. Feedback control based algorithms are predominantly used in active/semi-active suspensions that ignore the biodynamics of occupants. In the current work, a new 50 degree-of-freedom (DOF) combined nonlinear multi-occupant vehicle model is developed using the lumped parameter modelling (LPM) approach. The current model provides a platform for performing a combined study of ride, handling and occupant biodynamics. The model is capable of simulating the combined effect of sitting occupancies, road inputs and driving maneuvers on biodynamic responses. It is analyzed using MATLAB/SIMULINK functionalities and validated by independently correlating the computed responses with existing experimental results. A study is performed on ride behavior of a vehicle-occupant system under two different transient road inputs. In addition, the effect of road roughness on vehicle ride is also studied. Random road profiles are generated from road roughness spectrum given in the ISO 8608:1995 manual. Insights are developed into the ride dynamics of a vehicle traversing over roads of classes A, B, C and D at given test velocities. The effect of sitting occupancies and vehicle velocities on lateral dynamics is also studied. Results underscore the need for considering sitting occupancies while analyzing vehicle dynamics and also highlight the potential of the current model. Furthermore, a Moore-Penrose Pseudoinverse based feed-forward controller is developed and implemented in an independently acting semi-active seat suspension system. Feasibility of feed-forward control in primary suspensions is also investigated. Finally, issues of stability, performance and limitation of the controller are discussed.
132

Influência das frequências de ride no conforto e dirigibilidade veiculares na faixa linear de uso do veículo / Influence of ride frequencies in vehicle comfort and stability at linear range of driving

Francisco Ganzarolli 03 July 2012 (has links)
O tema do conforto na automobilística é bastante extenso e possuidor de muitas interpretações. A ideia central deste trabalho é definir e direcionar alguns métricos para que, durante as fases de conceituação e desenvolvimento de um veículo, seja possível ter um direcional de definição de componentes e atributos veiculares de modo a facilitar o direcionamento dos atributos no programa veicular, e assim atingir suas necessidades. Como exemplo empregado, é empregado um veículo de plataforma tipo B em desenvolvimento por uma montadora, o qual teve as molas de suspensão definidas e rigidezes laterais de eixos com base em material técnico interno equivalente aos estudos apresentados neste trabalho. É adotada uma abordagem inicialmente empírica conforme os primeiros estudos de suspensões independentes realizados neste continente, depois o trabalho é complementado com exigências de normas especificas para vibrações (ISO2361, ISO5008, BS6055) de modo a caracterizar energia vibracional e a interpretação pelo ser humano. Porém como hoje em dia as suspensões automotivas são muito mais complexas, existem componentes específicos para as várias condições de solicitação, deste modo a análise é limitada a situações de ride (conforto) primário e handling (dirigibilidade) em situações de sublimite na faixa linear (cerca de 0,5 g). Como conclusão dos estudos, é possível ter em um veículo atributos de estabilidade sem necessariamente prejudicar o conforto, pois sendo definidos corretamente os componentes elásticos da dinâmica vertical para situações estacionárias e de ride primário, é definido seu equilíbrio estacionário e assim não é necessário comprometimento dos atributos de outros componentes para compensar alguma deficiência existente. / The range of assumptions for ride comfort is considered very wide in the automotive world and they can assume lots of possible interpretations. The central idea in this work is define and manage some metrics that, during the concept and development phases of a vehicular program, be possible to follow a better direction for the attributes development and so reach the program targets. As the example in this work, a B platform typical vehicle is used and it is under development in a carmaker, its suspension springs and axle roll stiffness were setup with technical information similar to the ones presented in this work. The initial approach is empiric as occurred with the first independent suspension system studies in this continent and in the sequence, the work is complemented with standards for vibrational issues (ISO2361, ISO5008, BS6055), after this, finally how the vibrational energy is defined and perceived by human beings. The automotive suspensions of current days are very complex and there are lots of specific components to do a specific work, so the analysis are limited to primary ride and sub limit handling (up to 0,5 g). As conclusion, its possible setup a car that is comfortable and stable in the same time, since the elastic components for the vertical dynamics and steady state conditions are correctly set, so its correct balance is reached and no other components attributes are compromised to compensate any deficiency.
133

Lengvųjų automobilių stovėjimo aikštelių mieste vertinimas daugiatiksliais metodais / Evaluation of car parking lots in cities by multicriteria methods

Palevičius, Vytautas 22 December 2014 (has links)
Disertacijoje atliekama automobilių stovėjimo vietų poreikio mieste analizė. Pagrindinis darbo objektas – asmeninių kelionių automobilių stovėjimo vietų didmiestyje pasiskirstymo sistema. Ekspertiniu metodu sudaryta automobilių stovėjimo vietų mieste kriterijų sistema. Taikant daugiatikslius metodus kriterijams suteikti rangai ir apskaičiuoti jų svorių koeficientai, kurie leido nustatyti kriterijų prioritetus ir parinkti racionaliausias automobilių stovėjimo aikštelių išdėstymo vietas miesto teritorijoje. Pagrindinis darbo tikslas – pasiūlyti automobilių stovėjimo vietų mieste plėtros vertinimo modelį ir pateikti originalius automobilių stovėjimo aikštelių plėtros koncepcinius sprendinius. Disertaciją sudaro įvadas, 3 skyriai, bendrosios išvados, literatūros sąrašas, publikacijų sąrašas. Įvade trumpai aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimo objektas, formuluojamas darbo tikslas ir uždaviniai, aprašoma mokslinis darbo naujumas, ginamieji teiginiai. Įvado pabaigoje pristatomos autoriaus paskelbtos publikacijos, pranešimai konferencijose, nurodomas dalyvavimas tarptautiniuose seminaruose ir pateikiama disertacijos struktūra. Pirmame skyriuje pateikiama mokslinės literatūros ir kitų atliktų darbų analizė nagrinėjama tematika. Taip pat atlikta Lietuvos Respublikos, Europos Sąjungos ir kitų pasaulio šalių norminių dokumentų, reglamentuojančių lengvųjų automobilių stovėjimą skirtingose miesto teritorijose, analizė. Antrajame skyriuje atliekamas automobilių... [toliau žr. visą tekstą] / This dissertation examines the shortage of motor vehicle parking spaces in the city area. The object of this research is the allocation of passenger car parking spaces in cities. A criteria system for car parking spaces in cities was formed using the expert estimate method. By using multi-criteria methods, the criteria were grouped and their factor value was calculated, which helped to establish the priorities of the criteria and to determine the most rational places for parking lots in the city area. This research aims to suggest a model for developing an infrastructure of car parking spaces in the city and to present original conceptual solutions for the expansion of parking lots. The dissertation comprises an introduction, three chapters, general conclusions, a list of literature, and a list of publications. The introduction specifies the problem, describes the relevance of the paper, names the research object, the aim and objectives, its scientific novelty, and the defended statements. Finally, it lists publications and conference presentations of the author, describes the author’s participation in international seminars and presents the structure of the dissertation. Chapter one introduces the literature overview of the subject analysis and discusses the study of the scientific research carried out in this field. It also presents the examination of the normative documents in Lithuania, the European Union and in other countries, which regulate motor car parking in... [to full text]
134

Automobilių stovėjimo aikštelių "Statyk ir važiuok" plėtros Viliniuje, panaudojant GIS, analizė / Analysis of „Park and ride“ parkings developement analysis in Vilnius, using gis

Barauskaitė, Greta 16 June 2014 (has links)
Pagrindinis magistro darbo tikslas – parengti „Statyk ir važiuok“ stovėjimo aikštelių įrengimo pagrindimo metodiką ir pateikti siūlymus dėl tokių stovėjimo aikštelių plėtros Vilniaus mieste. Darbo užduotys – atlikti literatūros šaltinių apžvalgą, išanalizuoti Vilniaus miesto specialiajame plane pateiktus „Statyk ir važiuok“ stovėjimo aikštelių įrengimo variantus, atlikti studentų bei ekspertų nuomonės tyrimus aikštelių įrengimo klausimais, nustatyti, kokios aikštelės yra tinkamiausios, pasitelkus statistinę skaičiavimo metodiką. Šiame darbe taikomi trys statistiniai metodai – SAW , TOPSIS ir COPRAS. Skaičiavimų metu, pagal tam tikrus parinktus kriterijus, apskaičiuojama, kurių iš siūlomų aikštelių įrengimas yra tikslingiausias. Studentų nuomonės tyrimo metu nustatytos devynios tinkamiausios aikštelės, o ekspertų nuomonės tyrimo metu nustatyta po tris tinkamiausias aikšteles periferinėje, vidurinėje ir centrinėje miesto zonose. Gauti tyrimų rezultatai gali būti panaudoti atsižvelgiant į tolesnę aikštelių plėtrą Vilniaus mieste. Darbo tekstine dalį turi sudaryti 78 p., 1–17 pav., 1–16 lent. ir 5 priedai, taip pat turi būti išanalizuoti 34 literatūros ir informacijos šaltiniai. Grafinę baigiamojo darbo dalį turi sudaryti 1 brėžinys: 1. Tinkamiausios „Statyk ir važiuok“ aikštelės Vilniaus mieste M 1:50 000. / The main aim of this masters work is to arrange „Park and ride“ parking spots installation method and to introduce proposals for parking spots development in Vilnius. The main assignment of this work is to analyze literature sources, to analyze "Park and Ride" sites which are listed in "Vilnius city special plan", to organize student and expert opinion survey about the "Park and Ride" sites development, to identify which of the sites are the best for Vilnius city, using multi-criteria analysis. In this job, three methods were used - SAW, TOPSIS and COPRAS. During the counting, several criteria are chosen to prove which site is the bests. In the student survey nine sites were declared as the most appropriate for the Vilnius. In the expert survey, there were three most appropriate sites in every region - periphery, middle city part and the center. The results of the survey can be used for further "Park and Ride" sites development in Vilnius. The work consists of the 78 pages of text, 17 figures 16 tables and 5 annexes as well as analysis of 34 literature and information sources. The graphical part of the thesis consists of 1 drawing: 1. The most appropriate “Park and Ride” sites for Vilnius M 1:50 000.
135

On Active Suspension in Rail Vehicles

Qazizadeh, Alireza January 2017 (has links)
The topic of this PhD thesis is active suspension in rail vehicles whichis usually realized through sensors, controllers and actuation components.A well established example of an active suspension is the tiltingcontrol system used to tilt the carbody in curves to reduce centrifugalacceleration felt by passengers. Active suspension for rail vehicles is beingstudied since 1970s and in this PhD thesis it has been tried to expandon some aspects of this topic.This study extends the research field by both experimental and theoreticalstudies. In the first phase of the study which led to a licentiatedegree the focus was more on experimental work with active verticalsuspension (AVS). This was implemented by introducing actuators inthe secondary suspension of a Bombardier test train, Regina 250, in thevertical direction. The aim has been to improve vertical ride comfort bycontrolling bounce, pitch and roll motions.In the second phase after the licentiate, the studies have been moretheoretical and can be divided into two parts. The first part of the workhas been more focused on equipping two-axle rail vehicles with differentactive suspension solutions for improving the vehicle performanceregarding comfort and wheel-rail interaction. Three papers are writtenon active suspension for two-axle rail vehicles. Two of the papers discussthe use of H¥ control for wheelset guidance in curves to reducewheel-rail damage. The third paper shows that by use of active verticaland lateral suspension (AVS and ALS) in two-axle rail vehicles goodcomfort can be achieved as well. The paper then studies how the threeactive suspension systems (ALS, AVS, and ASW) interact once implementedtogether on a two-axle rail vehicle.The second part is a study on safety of active suspension systems.The study discusses a possible procedure to ensure that a designed activesuspension for a rail vehicle will be safe in all possible failure situations. / <p>QC 20170602</p>
136

Péče o nehmotné kulturní dědictví na příkladu jízdy králů / Care of the Intangible Cultural Heritage: Case of the Ride of Kings

Orságová, Anna January 2013 (has links)
Care of the intangible cultural heritage is nowadays dependent on several elements. The main element is people and community in the places where the habit or tradition is still kept. But their effort must be supported by national and international authorities who invest considerable resources into their preservation. Except this also the general awareness of public that is a guarantee of passing the tradition to the next generations is very important. On the example of the Ride of Kings there is captured historical evolution of the tradition, which during the previous century undergo the change in the people's celebrations. By their formation was conditioned preservation of tradition, which began to vanish in the second half of the 20th century. Key words Intangible cultural heritage, cultural people's tradition, Ride of the Kings, folklore.
137

Druhá římská jízda Karla IV. / The second Roman ride of the Charles the Fourth

Obůrková, Radka January 2013 (has links)
The thesis "The Second Roman Ride of the Charles the Fourth" tries to cover the whole campaign of the Emperor Charles IV. between years 1368 and 1369. Also, thesis follows the basic questions related to the issues of the royal court during the journey. The first of those questions is about accompaniment of the Emperor Charles IV. on his journey across the Italian territory and how the court was transformed during the ride to Rome and back. The second question points out the effort to build the court of the Elizabeth of Pomerania, who was crucial person of the second Roman ride where she did not travel alongside the emperor. The last question attempts to describe the undergirding of the court during the campaign in italian cities - how the emperor and his court was accepted and welcomed, accommodated, supllied and gifted.
138

The Uber Boundary : Contextualizing the Organizational Boundary of a Digital Platform Organization

Furulind, Johanna, Sjöqvist, Olivia January 2019 (has links)
Digital platform organizations challenges the organizational landscape by utilizing technology enabling cost efficient transactions. Uber is a commonly known example of such an organization, where tensions have arisen in various local contexts due to that the organization draw their boundary tightly around the platform to the benefit of organizational efficiency. Uber has as a consequence, been highly questioned in its liability of their primary operations: Is it a technology platform, or a transportation firm?   This thesis sets out to answer:  How is the organizational boundary of Uber challenged in various local contexts? The purpose is to provide an explanation towards how the organizational boundary of a digital platform organization could be understood in relation to local context, and how it can or cannot evolve in regards to these contexts. The results show that context matters for the boundary of Uber. In addition, a pattern amongst the context specific events emerged influencing the boundary. These can be categorized into four configurations: Adjusting, Expanding, Withdrawing and Intertwining. Each of the configurations explain the underlying reasons for the varying fluctuations the boundary of Uber show, and thus answer how the organizational boundary of Uber is challenged in various local contexts.
139

Étude expérimentale et numérique de l'écoulement autour d'une ride isolée / Experimental and numerical study of flow over an isolated ripple

Hamidouche, Souria 09 December 2013 (has links)
L'étude de l'écoulement à l'aval d'une ride a un intérêt primordial dans la dynamique et l'évolution des rivières, des milieux côtiers ou des estuaires. Une des questions au coeur de ces écoulements est liée aux mécanismes d'interaction entre les particules et l'écoulement. Cette interaction donne souvent lieu à la formation de structures ondulées (rides ou dunes). Ce couplage est engendré au niveau de l'écoulement moyen, de la forme de la dune mais aussi au niveau de la macro turbulence et des structures tourbillonnaires instationnaires générées par la présence même des formes sédimentaires. L'identification des différents mécanismes et processus hydrodynamiques générés par la présence de dunes ou rides est exposée en détail par l'examen de l'écoulement laminaire à l'aval d'une ride fixe et isolée. Des techniques de mesure optiques 2D (PIV, visualisations) et 3D (Stéréo-PIV, tomographie laser) couplées à une étude numérique avec un code industriel, permettent de mettre en évidence l'instationarité, la tridimensionnalité de l'écoulement ainsi que la dynamique tourbillonnaire de la zone de recirculation à l'aval de la ride. L'impact de l'écoulement turbulent sur la naissance de dunes isolées est analysé au moyen d'une étude détaillée sur le transport de particules à partir d'essais menés en canal hydro-sédimentaire. Le rôle particulier de la zone de recirculation à l'aval de la dune est mis en évidence à l'aide d'un suivi spatio-temporel du transport des particules entre sa crête et sa face d'avalanche. Finalement, l'analyse et l'influence des conditions hydrauliques sur le seuil critique de mise en mouvement d'un lit de particules ainsi que la formation et la migration d / The aim of this study is to examine the processes leading to development a bed river, estuary or coastal environments morphology. The ability to investigate the complex nature of the interaction between fluids and sediments mechanisms and its role in bed transport and river stability is important to understand river evolution. Dunes or ripples are in frequent interaction with the bed. Hence, the topology of dune is related to the macroturbulence of the flow, mean flow field and the instantaneous structures of the vortices generated by these forms. Details of different mechanisms and hydrodynamic process generated behind a fixed single ripple are exposed by examining a laminar flow over the dune itself. Measurements with two-component Particle Image Velocimetry, three-component Stereo-PIV and flow visualization coupled with a numerical studies are performed to acquire and to obtain a detailed knowledge of the flow over the dune concerning the three-dimensionality, the instantaneous behavior of the flow and the large dynamic of vortex in the recirculation zone along the ripple. A set experiment generating turbulent flow is conducted in a hydro-sedimentary channel to detail the quantitative measurement of bedload transport processes in order to determine the effects of the turbulent flow on dune creation. A spatio-temporal monitoring of particles transport from crest to dune slip face is conducted to point the particular role of the recirculation region. Finally, the analyze and the effect of hydraulics conditions on the critical shear stresses for incipient particle motion as well as the formation and the migration of the mobile dune are emphasized by a geomorphological st
140

Salvage historiography: viewing, special effects, and Norman O. Dawn's unpreserved archive

DeLassus, Leslie Marie 01 January 2016 (has links)
This dissertation excavates the work of early special effects cinematographer Norman O. Dawn in order to explore film spectatorship, the ephemerality of the cinematic image, and motion picture preservation and archival practices. Best known for his innovations of glass and matte shot techniques, Dawn produced 861 composite images while working in the U.S. film industry between 1906 and 1954. Although technological film historians acknowledge the importance of Dawn’s innovations to the development of motion picture special effects, the composite images themselves as well as the films for which they were produced remain in relative obscurity. Rather than attempting to recover these objects for inclusion in an existing film canon, my research interrogates their obscurity by analyzing Dawn’s special effects processes against the broader economic concerns that inform the dominant practices of the US film industry during the first half of the twentieth-century. My research begins with the Norman O. Dawn collection housed at the Harry Ransom Humanities Research Center, which is the most comprehensive historical record of Dawn’s work in the film industry. Constructed by Dawn himself between 1962 and 1974, this collection consists of 164 poster-sized collages of archival ephemera that illustrate the special effects processes employed in the production of 235 composite images for eighty-five films. While these eighty-five film titles constitute a tentative corpus upon which to base my research, seventy of these films are lost, which raises questions concerning the relationship between motion picture preservation and film history, specifically why these films have not been preserved while others have and to what extent the economic imperatives of the film industry have determined these conditions. I address these questions in my analysis of archival material related to these films, finding that they traverse several distinct domains of film practice—including early scenic footage for newsreels and the amusement park ride Hale’s Tours of the World, early one-reel travel films, silent-era studio shorts, serials, and B features, and poverty row and independently-produced silent and sound feature-length films—thereby situating Dawn’s special effects at the intersection of the early and contemporary cinematic modes often aligned in studies of cinematic special effects. I argue that this heterogeneous corpus points to a studio-era Hollywood cinema alternative to the classical model, largely forgotten because it is dominated by low-budget product intended to supplement more costly feature films. In contrast to the classical model, this alternate cinematic mode emphasizes the scenic and thrilling elements that characterize both early exhibitionist films and contemporary effects-driven blockbusters. In this context, Dawn’s special effects processes constitute a historically marginalized practice precisely because they are non-routine techniques that provide cost-effective means to produce otherwise economically infeasible scenes, and, as such, operate on the periphery of conventional film production.

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