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Adhérence d'une interface structurée polymère / silicium pour l'encapsulation par transfert de film : caractérisation expérimentale et modélisation / Study of adhesion and decohesion of thin films for MEMS' encapsulationCuminatto, Coraly 13 December 2012 (has links)
En microélectronique, certains dispositifs (MEMS) nécessitent une couche de protection appelée encapsulation pour assurer un fonctionnement optimal. Ce procédé met en jeu une couche structurée de polymère BCB (benzocyclobutène). Celle-ci est en contact avec unsubstrat de silicium d’un côté et une couche de nickel de l’autre. Une compréhension du comportement de ces interfaces et primordiale. L’objectif de cette thèse est la caractérisation de l’énergie d’adhérence des interfaces discontinues Ni/BCB et BCB/Si. Deux essaismécaniques (test de flexion 4-points et insertion de lame) ont été mis en œuvre. Les modèles analytiques mis au point dans le cas d’une interface continue ont servi à l’exploitation de ces essais mais ont aussi montré leur limite. La structuration de l’interface induit des effets géométriques et des effets d’échelle qui ne sont pas bien pris en compte par les modèles classiques. Pour pallier à cette difficulté, un modèle analytique modifié est proposé pour le test d’insertion de lame, ainsi que des calculs de simulation numérique. Ils mettent en avant l’influence des paramètres de la structuration : taille des motifs, espacement. / In microelectronics, some devices (MEMS) need to be encapsulated by a protective layer for optimal performances. This technique involves a patterned layer made of BCB polymer (benzocyclobutene). This layer is between a nickel film and a silicon substrate. A good understanding of those two interfaces is of first importance. The aim of this thesis is the mechanical characterization of the fracture energy of the Ni/BCB and BCB/Si patterned interfaces. Two mechanical tests (the 4-points bending test and the wedge test) have been selected in that purpose. Analytical models are well established to analyze those tests but for continuous interfaces. With patterned ones, those models are limited and do not take into account all the size effects and the geometrical effects induced by the patterning. A modified analytical model is proposed for the wedge test in order to overcome these limitations. Numerical studies are also carried out to complement the study. Patterning effects such as the size of the patterns and the space between them are enhanced.
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Interface WEB para gerenciamento e utilização de clusters para processamento paralelo / A WEB interface for the use and management of parallel processing in clustersElaine Patricia Quaresma Xavier Lett 17 February 2003 (has links)
Este trabalho descreve um projeto simples de gerenciamento de clusters que apresenta uma interface de usuário para as tarefas mais comuns de uso e gerenciamento de um cluster utilizado como máquina paralela. A partir do estudo de vários softwares existentes hoje, o sistema projetado foi adequado às necessidades do cluster do Laboratório de Processamento Paralelo Aplicado do Instituto de Física de São Carlos. O sistema é baseado em páginas HTML e scripts CGI. O uso de HTML e CGI se demonstrou apropriado para o desenvolvimento desse tipo de sistemas. / This work describes a simple cluster management system that operates as a user interface for some common user and manager tasks performed on a cluster used as parallel machine. We studied some cluster management systems from the literature and then designed a system with the needs of our research laboratory in mind. The system was implemented using HTML pages and CGI scripts. The use of HTML and CGI was found adequate for this type of systems.
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Dispositivo da interface. Um estudo sobre tecnologias de comunicação / Dispositivo da interface. Um estudo sobre tecnologias de comunicaçãoRicardo Augusto Silveira Orlando 05 February 2007 (has links)
As interfaces de usuário ganharam relevância no contexto da sociedade tecnológica com a emergência do que Nicholas Negroponte chamou de vida digital, passando a ocupar posição de destaque nos estudos de comunicação. Tomando como pressuposto a relevância das interfaces, este trabalho discute as relações que fazem delas um ponto de esforço na atualidade, a partir da concepção foucaultiana de dispositivo de poder. As análises partem dos alvos eleitos no debate sobre as características que uma interface deve possuir para mapear os contornos do dispositivo. Levam em conta o projeto de interface e a idéia de usabilidade para verificar como são problematizadas as relações que buscam constituir um sujeito-usuário, vinculado assim com a tecnologia, dotando-o de poderes para agir. Avaliam-se alguns dos modos de interação elencados na bibliografia que discute as peculiaridades dos projetos. Depois, são analisados aspectos colocados como necessários no projeto pensado como o design de uma experiência a ser vivenciada pelos usuários no espaço da interface, retomando os pontos estratégicos do modo de interação característico da interface gráfica de usuário (GUI). As relações estabelecidas com a tecnologia são consideradas como relações de poder. A proposta é contribuir para o debate da questão da técnica na sociedade contemporânea, uma vez que nela a comunicação aparece como fundamento e ao mesmo tempo é implicada de modo substancial. Dispositivo da interface é uma configuração parcial de algo difícil de ser mapeado em sua totalidade, que aqui procura marcar a importância da sociedade pensar suas relações com a técnica, frisando as estratégias finas que são buscadas para ligar os sujeitos à informática e, por conseguinte, à ordem digital. / User`s interfaces got relevance among technological society environment due to the emergency of what Nicholas Negroponte called being digital, and achieving a highlighted position in studies on communication. Considering interface relevance, this study discusses relations that make interfaces an effort spots nowadays, from Foucauldian conception of power apparatus (dispositif). Analyses start from goals elected in the debate on the characteristics an interface must have to map the apparatus outlines. They consider the interface project and usability idea to verify how the relations trying to build a subject-user are problematized, relating it to technology, giving power to act. Some interaction modes listed in the bibliography discussing projects` peculiarities have been evaluated. Then aspects considered necessary are analysed in the project thought as the design of an experience to be experienced by users in the interface space, recovering strategic points of the characteristic interaction mode of graphic user interface (GUI). Relations established with technology are considered as power relations. This proposal is contributing to debate technical issue in the contemporary society, once communication appears as a foundation and is implied in a substantial mode at the same time. Interface dispositif is a partial configuration of something difficult to be totally mapped here intending to stress the importance for the society thinking of their relations with the technique, emphasizing fine strategies searched to link subjects to information and then to the digital order.
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About the Importance of Interface Complexity and Entropy for Online Information SharingSpiekermann-Hoff, Sarah, Korunovska, Jana January 2014 (has links) (PDF)
In this paper, we describe two experiments that show the powerful influence of interface complexity and
entropy on online information sharing
behaviour. 134 participants were asked to do a creativity test and
answer six open questions against three different screen backgrounds of increasing complexity. Our data
shows that, as an interface becomes more complex and has more entropy users refer less to themselves
and show less information sharing breadth. However, their verbal creativity and information sharing
depth do not suffer in the same way. Instead, an inverse U shaped relationship between Interface
complexity and creativity as well as information sharing depth can be observed: Users become more creative and thoughtful until a certain tipping
point of interface complexity is reached. At that point, creativity and th inking suffer, leading to significantly less disclosure. This result challenges the general HCI assumption that simplicity is always best for computers interface design
, as users'creativity and information sharing depth initially increases with more interface complexity. Our results suggest that the Yerkes Dodson Law may be a key theory underlying online creativity and depth of online disclosures.
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Mouvement brownien des particules colloïdales partiellement mouillées / Brownian motion of partially wetted colloidal particlesBoniello, Giuseppe 06 February 2015 (has links)
La dynamique de particules colloïdales à l'interface entre deux fluides joue un rôle central dans la micro-rhéologie, l'encapsulation, l'émulsification, la formation de biofilms, la décontamination de l'eau. En outre, ce sujet est également stimulant d'un point de vue théorique en raison de la complexité de l'hydrodynamique à l'interface et du rôle de la ligne de contact. Malgré ce grand intérêt, le comportement d'une particule à une interface fluide n'a jamais été caractérisé directement. Dans cette thèse, nous étudions le mouvement brownien de billes micrométriques de silice et de sphéroïdes de polystyrène à une interface eau-air. Nous contrôlons expérimentalement tous les paramètres d'intérêt. L'angle de contact des billes est finement ajusté dans la gamme 30°-140° par des traitements chimiques de surface et mesuré in situ par interférométrie. Le rapport d'aspect de particules sphéroïdales varie dans la gamme 1 -10 par étirage de billes sphériques commerciales. Les dynamiques de translation et de rotation sont suivies par particle tracking. Contre intuitivement et contre tous les modèles hydrodynamiques la diffusion est beaucoup plus lente que prévu. Pour expliquer cette dissipation supplémentaire nous concevons un modèle tenant compte de la contribution des fluctuations thermiques de l'interface à la ligne de contact. Les fluctuations donnent origine à des forces aléatoires qui s'ajoutent à celles dues aux chocs de molécules. Le théorème de fluctuation-dissipation permet d'obtenir la friction supplémentaire associée à ces forces flottantes. La friction totale est discutée en termes d'hétérogénéités de la surface des particules et d'ondes capillaires à l'interface. / The dynamics of colloidal particles at the interface between two fluids plays a central role in micro-rheology, encapsulation, emulsification, biofilms formation and water remediation. Moreover, this subject is also challenging from a theoretical point of view because of the complexity of hydrodynamics at the interface and of the role of the contact line. Despite this great interest, the behavior of a single particle at a fluid interface was never directly characterized.In this thesis, we study the Brownian motion of micrometric spherical silica beads and anisotropic polystyrene spheroids at a flat air-water interface. We fully characterize and control all the experimentally relevant parameters. The bead contact angle is finely tuned in the range 30-140° by surface treatments and measured in situ by a homemade Vertical Scanning Interferometer. The spheroid aspect ratio varies in the range 1 – 10 by stretching of commercial beads. The translational and the rotational dynamics are followed by particle tracking.Counter-intuitively, and against all hydrodynamic models, the diffusion is much slower than expected. To explain this extra dissipation we devised a model considering the contribution of thermally activated fluctuations of the interface at the triple line. Such fluctuations couple with the lateral movement of the particle via random forces that add to the ones due to the shocks of surroundings molecules. Fluctuation-dissipation theorem allows obtaining the extra friction associated to this additional mechanism. The fitting values of the total friction are discussed in term of the typical scales of particle surface heterogeneities and of surface capillary waves.
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Rhéologie d'interface liquide/air chargées de grains : vers la consolidation d'un milieu aéré / Rheology of grain-loaded liquid/air interfaces : towards the consolidation of an aerated mediumTimounay, Yousra 11 October 2016 (has links)
Les mousses liquides sont dans un état métastable. Un moyen de les stabiliser est d’y incorporer des particules solides. Lorsqu’elles sont hydrophobes, ces particules s’attachent aux interfaces liquide-air de la mousse et changent radicalement la rhéologie des films séparant les bulles. L’objectif de cette thèse est d’étudier expérimentalement deux composants élémentaires des mousses chargées en particules, à savoir les films et les bulles. La rhéologie des films particulaires est sondée grâce à des expériences d’éclatement et de compression alors que la résistance des bulles armurées est étudiée en faisant varier leur pression interne. En utilisant l’imagerie rapide, nous montrons d’abord que les particules qui pontent les deux interfaces du film peuvent inhiber l’ouverture d’un trou et que pour les autres configurations, la dynamique de rétraction peut être décrite par un équilibre inertio-capillaire pour des fractions surfaciques en particules <0.6 environ. L’étude de la dynamique de rétraction des films particulaires par Particle Image Velocimetry a permis de les caractériser par une viscosité effective qui diverge à la transition de jamming. De plus, les films particulaires flambent à fraction surfacique en particules élevée indiquant une transition d’un comportement liquide vers un comportement solide. En ce qui concerne les bulles particulaires, nous avons montré l’existence de pressions critiques 10 fois plus grandes que la pression de Laplace avant que les bulles ne se déforment aussi bien en dépression qu’en surpression ; la tension effective dans le plan de la coque granulaire est donc 10 fois plus importante que la tension dans un film liquide. Une fracture, correspondant à l’étirement du film liquide, est par ailleurs observée sur les bulles particulaires en surpression. En adoptant une approche élastique, le critère de Griffith permet de retrouver le bon ordre de grandeur de la pression de fracture / Liquid foams are in a metastable state. One way to stabilize them is incorporating solid particles. When hydrophobic, these particles attach to liquid-air interfaces of the particle-laden foam inducing a drastic change in the rheology of the films between bubbles. The aim of this thesis is to study experimentally two elementary components of particle-laden foams, namely soap films and bubbles. The rheology of particulate films is probed through bursting and compression experiments while the resistance of armored bubbles is studied by inner pressure variations. Using high speed photography, we first show that particles bridging both liquid-air interfaces of a liquid film can resist hole opening and that the retraction dynamics for the other configurations can be described by a balance between inertia and capillarity for surface fractions of particles <0.6 approximately. Then studying the retraction dynamics of particulate soap films by Particle Image Velocimetry, we characterized these systems by an effective viscosity that diverges at the jamming transition. Moreover, buckling is observed at high surface fraction of particles indicating a transition from liquid-like to solid-like behavior. Concerning particulate bubbles, we showed the existence of pressure thresholds 10 times greater than Laplace pressure that need to be exceeded in order to observe a deformation in depression and overpressure experiments; the effective tension in the granular shell is thus 10 times greater that the tension in a liquid film. When inflated, a fracture corresponding to the stretching of the liquid film appears on particulate bubbles. Through an elastic approach, Griffith’s criterion gives the right order of magnitude of fracture pressures
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Photoluminescence Techniques for the Characterization of Photovoltaic Interfaces / Techniques de Photoluminescence pour l'étude des Interfaces PhotovoltaïquesXu, Ming 08 April 2016 (has links)
Dans ce travail, nous avons appliqué des techniques de photoluminescence en régime stationnaire (PL) et photoluminescence en régime modulé (MPL) à l'étude d'hétérojonctions formées entre du silicium cristallin (c-Si) et du silicium amorphe hydrogéné (a-Si:H). Plus précisément, nous avons comparé des échantillons constitués de dépôts de (n)a-Si:H, (i)a-Si:H, (n)a-Si:H/(i)a-Si:H, et (p)a-Si:H/(i)a-Si:H sur des wafers de (n) c-Si de haute qualité électronique. Les mesures en fonction de la température montrent que la durée de vie des porteurs en excès diminue lorsque la température diminue, ce qui peut être qualitativement reproduit par la simulation dans un mécanisme de recombinaison de type Shokley-Read-Hall (SRH) en tenant compte du niveau d’énergie du dopant (phosphore) dans le substrat et de niveaux peu profonds électroniquement actifs à l'interface.Nous avons également étudié des échantillons dopés par implantation d'ions puis passivés par AlOx, a-Si:H et SiC. Des signatures de dislocations sont révélées à basse température par des pics supplémentaires de PL.Nous avons également comparé les résultats de cartographies de PL et de durée de vie obtenues par l'analyse de l'amplitude de MPL, et par l'analyse de son déphasage. Il est constaté que les propriétés optiques des échantillons ont un grand impact sur la cartographie PL, ce qui pourrait conduire à une conclusion erronée sur leur homogénéité. En revanche, les cartographies de durée de vie sont moins sujettes à des variations de paramètres optiques et au bruit provenant du processus de mesure, phénomènes qui ne sont pas intrinsèques à l'échantillon étudié.La nature différentielle de la mesure MPL est étudiée. Nous démontrons la notion de durée de vie à l'état stationnaire et de durée de vie différentielle. Nous analysons différents types de recombinaisons avec la durée de vie MPL et avons mis en œuvre des simulations des hétérojonctions a-Si:H/c-Si. Nous constatons que dans le domaine d'excitation intéressant pour le photovoltaïque, la durée de vie différentielle est souvent inférieure à la durée de vie à l'état stationnaire. Nous faisons aussi des comparaisons entre les durées de vie obtenues par mesures dites QSSPC et MPL et montrons qu'elles sont en fait égales.La combinaison des techniques de PL et de MPL nous a permis d'étudier le coefficient de recombinaison radiative en fonction de la température. Les résultats publiés jusqu'ici dans la littérature couvrent la plage de température de 300 K à 90 K. Dans cette plage, nos résultats sont en très bon accord avec ces résultats publiés précédemment. Mais, grâce à notre système de mesure et à la combinaison PL/MPL, nous avons obtenu des valeurs de ce coefficient jusqu’à 20 K et nous avons pu proposer une fonction polynômiale du cinquième degré qui permet de bien reproduire les variations en fonction de la température sur toute la plage de 20 K à 300 K.Dans une dernière partie de la thèse, les propriétés de transport de porteurs et l'effet de couplages sont étudiés dans des empilements de quantum dots. Nous avons examiné les quantum dots de InAs qui croissent de manière ordonnée en formant des chaînes à partir d'une couche tampon en InGaAs (couche dite de "cross hatch pattern"). Nous avons caractérisé par PL des monocouches ainsi que des multicouches empilées de chaînes de quantum dots. L'effet de couplage entre dots dans le plan est observé sur des échantillons de monocouches, et nous remarquons une inhibition du couplage vertical entre couches qui est expliqué par l'effet du champ de déformation de la couche de cross hatch pattern. / Silicon solar cells remain the driving technology and dominate the photovoltaics market. Hydrogenated amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction cells achieve the best efficiency in silicon cells to date (25.6%). A great part of this achievement is assigned to the improvement of the passivation of the emitter/absorber interface. In that regard, luminescence techniques whether Photoluminescence (PL) or Modulated photoluminescence (MPL), are particularly appropriate to investigate surface defects and effective carrier lifetime.In this work, we developed a PL/MPL setup coupled to a helium cooled cryostat to the study of a-Si:H/c-Si heterojunctions. Considering the modulated nature of the MPL, we introduced the concept of steady state lifetime and differential lifetime. Through simulations, we analyzed different types of recombination mechanisms and found that the differential lifetime is lower than the steady state lifetime. We also benchmarked the lifetime determined by photoconductance decay measurements and the MPL lifetime and demonstrated that they are actually equal.We have analyzed various samples of a-Si:H/c-Si heterojunctions from multiple sources, particularly within the framework of the European project HERCULES (High Efficiency Rear Contact solar cells and Ultra powerful moduLES). The samples are composed of various doping and passivation layers such as AlOx, a-Si:H and a-SiC:H fabricated on high quality (n)c-Si wafers. The temperature dependent measurements show that the excess carrier lifetime decreases when temperature decreases, which is explained by the Shockley-Read-Hall recombination model at the heterojunction interface. The combination of PL and MPL measurements have enabled us to determine the radiative recombination coefficient in crystal silicon as a function of temperature. Our measurements have extended the original data to 20 K. We propose a fifth order polynomial of the radiative recombination coefficient as a function of temperature in the range of 20 to 300 K and it agrees very well to others’ work.We also investigated the possibility to extend the system to carry out PL and MPL mapping in order to extract the cell homogeneity and the lifetime distribution across the sample. We found that the optical property of sample has a significant impact on the PL mapping and could lead to incorrect conclusion with respect to the homogeneity. However the lifetime mapping from MPL produces imaging that is less prone to variation of optical properties.At last, we utilized the temperature dependent micro PL to investigate the coupling of InAs quantum dot chains (QDC) stacks grown on InGaAs cross hatch patterns separated with a 10 nm GaAs layer. The PL spectra are dominated by the top-most stack, indicating that the QDC layers are nominally uncoupled. However, under the high excitation power densities achievable with the micro PL system, when the high-energy peaks of the top stack are saturated, low-energy PL peaks from the bottom stacks emerge as a result of the carrier transfer across the GaAs spacers. These unique PL signatures contrast with the state-filling effects in conventional, coupled QD stacks and serve as a means to quickly assess the presence of electronic coupling in stacks of dissimilar-sized nanostructures.
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Méthodes d’apprentissage et approches expérimentales appliqués aux réseaux d’interfaces protéiques / Learning methods and experimental approaches applied on protein interface networksAchoch, Mounia 30 September 2015 (has links)
Cette étude s’inscrit dans le cadre d’un problème biologique et son objectif est de comprendre les mécanismes d’assemblage des protéines. L’assemblage d’une protéine en oligomère est particulièrement important car il est impliqué dans de nombreuses pathologies allant de l’infection bactérienne aux maladies de type Alzheimer ou même des cancers. L’assemblage protéique est un mécanisme de combinaison de deux ou plusieurs chaînes protéiques, il est aussi par ailleurs souvent utilisé par les organismes vivants pour déclencher une activité biologique. La sous unité B de la toxine du choléra(CtxB5), qui appartient à la famille des toxines AB5, est étudiée comme modèle principal de l’assemblage. Des résultats expérimentaux ont fourni des informations sur l’assemblage de la toxine mettant en avant l’implication de certains acides aminés. La première question que j’ai abordée pendant ma thèse était de comprendre leur rôle et de voir si les approches réseaux étaient pertinentes pour y répondre. J’ai pu montrer en utilisant des mutations d’acides aminés que ces derniers s’influençaient entre eux suivant des mécanismes en cascade ou de « Peer to Peer » afin de coordonner les étapes de l’assemblage (les chapitres 4, 5 et 6). La structure et la fonction des protéines sont définies par des séquences d’acides aminés qui varient naturellement en raison de mutation génétique. J’ai donc décidé d’élargir ce champ d’investigation pour voir si le mécanisme en cascade était généralisable comme moyen de perturber une structure de protéine par le biais d’une mutation. Ici il s’agit de comprendre les changements de structure liés à des mutations et pouvant menés à des maladies. J’ai tout d’abord étudié des jeux de données pour connaître les caractéristiques réseaux de protéines saines (chapitre 7, 8 et 9), avant de regarder l’effet de la mutation systématique de chacun des acides aminés de CtxB5 sur sa structure globale (chapitre 10 et 11). Les mutations peuvent engendrer des changements de structure modérés ou très grand autour de l’acide aminé muté ou à des distances très éloignées. Ces résultats sont consistants avec tous les effets connus de mutation : robustesse (maintien de la fonction), évolution ou adaptation (émergence d’une nouvelle fonction) et fragilité (pathologies). Les résultats montrent aussi une faible corrélation entre le nombre de contacts d’un acide aminé et la quantité de changement structuraux induit par sa mutation. Il n’est donc pas simple d’anticiper l’effet d’une mutation : Le dernier chapitre de ma thèse aborde ce problème (chapitre 12). / The aim of this study is to understand protein assembly mechanisms. The assembly of a protein in an oligomer is particularly important because it is involved in many pathologies going from bacterial infection, Alzheimer like diseases or even some cancers. Protein assembly is the combination of two or more protein chains to induce a biological activity. The B subunit of the cholera toxin pentamer (CtxB5), which belongs to the family of AB5 toxins, is studied as the main model of assembly. Experimental results have provided information on the assembly of the toxin highlighting the involvement of certain amino acids. The first problem addressed in my thesis is to understand their role and see if network approaches are relevant to such investigation. I was able to show using amino acid mutations, that amino acids influence each other by cascade or "peer to peer" mechanisms in order to coordinate the various steps of the assembly (Chapters 4, 5 and 6). The structure and function of the proteins are defined by amino acid sequences which naturally vary due to genetic mutation. So I decided to expand this field of investigation to see if the cascade mechanism was generalized as a mean of disrupting a protein structure. Here it is to understand how a protein loses its function by way of a significant change of structure upon mutation. First, I studied dataset to know the characteristics of healthy protein networks (Chapter 7, 8 and 9), and after I looked at the effects of the systematic mutation of each amino acid of CtxB5 on its overall structure (Chapter 10 and 11). Mutations led from moderate to very large structural changes around the mutated amino acid or at long distances. These results are consistent with known effects of mutation: robustness (maintenance function), evolution or adaptation (emergence of a new feature) and fragility (pathologies). The results also show a weak correlation between the number of amino acid contacts of the mutated amino acid and the amount of structural change induced by its mutation. It is therefore not easy to anticipate the effect of a mutation: The last chapter of my thesis addresses this problem (Chapter 12).
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User | InterfaceKapadia, Niraj 16 August 2011 (has links)
No description available.
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An integrated human factors approach to design and evaluation of the driver workspace and interface: Driver perceptions, behaviors, and objective measuresKyung, Gyouhyung 07 July 2008 (has links)
An ergonomic driver workspace and interface design is essential to ensure a healthier and comfortable driving experience in terms of driver perceptions, postures, and interface pressures. Developing more effective methods for driver-side interior design and evaluation, hence, requires thorough investigation of: 1) which perceptual responses are more relevant to ensuring ergonomic quality of a design, 2) the interrelationships among perceptual responses and objective measures, and 3) whether current assumptions regarding driver behaviors, and tools for specifying these behaviors, are valid for the design and evaluation. Existing studies, however, have rarely addressed these topics comprehensively, and often have been conducted with unsubstantiated assumptions. In contrast, this work sought to address these topics in a way that jointly considers characteristics of driver perceptions, behaviors, and objective measures to develop an improved design and evaluation methodology for driver workspace and interface, and that can also investigate the validity of implicit assumptions regarding perceptual relevance and drivers' behaviors.
The first part of this work investigated drivers' perceptions in relation to driver workspace design and evaluation. Specifically, it examined the efficacy of several perceptual ratings, when used for evaluating automobile interface design. Results showed that comfort ratings were more effective at distinguishing among interface designs, in contrast to the current common practice of using discomfort ratings for designing and evaluating interface designs. Two distinct decision processes to relate local to global perceptions were also identified (i.e., global comfort as an average of local comforts, and global discomfort predominantly influenced by maximal local discomforts). These findings were observed consistently across age and cultural groups. In addition, this work provided empirical support for an earlier hypothetical comfort/discomfort model, which posited comfort and discomfort are complementary, yet independent entities.
In order to facilitate the integration of driver perceptions and dynamic behaviors into driver workspace design and evaluation, the second part of this work clarified the relationships between perceptual ratings and various types of driver-seat interface pressure. Interface pressure was found to be more strongly related to overall and comfort ratings than to discomfort ratings, which is also in marked contrast with existing work that has focused on identifying association between discomfort and interface pressure. Specific pressure interface requirements for comfortable driver workspace design and evaluation were also provided.
Lastly, this work specified more rigorous driving postures for digital human models (DHMs), based on actual drivers' perceptions, postural sensitivity, and static behavioral characteristics, to facilitate proactive design and evaluation that enables cost/time efficient vehicle development. Drivers' behavioral characteristics observed in this work were applied to the driver workspace design. First, postural sensitivity obtained by using a psychophysics concept has been applied to determination of core seat track ranges. Second, postural data have been used: 1) to review relevant industry standards on driver accommodation, 2) to investigate whether driving postures are bilaterally asymmetric, 3) to provide comfortable joint ranges, and lastly 4) to identify drivers' postural strategies for interacting with a vehicle.
Overall, this work identified three important behavioral characteristics, specifically a bilateral imbalance in terms of interface pressure, bilaterally asymmetric joint posture, and postural strategies identified by cluster analysis. Such characteristics can be embedded in DHMs to describe more accurately actual driver behaviors inside a driver workspace, which is deemed to be a fundamental step to improved virtual ergonomic vehicle design and evaluation. In addition, the strategy-based classification method used in this work can be extended to simulate and predict more complex human motions. Practical and fundamental findings of this work will facilitate efficient and proactive design and evaluation of driver workspace and interface, and will help provide a healthier driving experience for a broader range of individuals. / Ph. D.
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