Teses / dissertações sobre o tema "Virtual fields"

This thesis presents novel techniques for the generation and real-time rendering of globally illuminated environments with surfaces described by arbitrary materials. Real-time rendering of globally illuminated virtual environments has for a long time been an elusive goal. Many techniques have been developed which can compute still images with full global illumination and this is still an area of active flourishing research. Other techniques have only dealt with certain aspects of global illumination in order to speed up computation and thus rendering. These include radiosity, ray-tracing and hybrid methods. Radiosity due to its view independent nature can easily be rendered in real-time after pre-computing and storing the energy equilibrium. Ray-tracing however is view-dependent and requires substantial computational resources in order to run in real-time. Attempts at providing full global illumination at interactive rates include caching methods, fast rendering from photon maps, light fields, brute force ray-tracing and GPU accelerated methods. Currently, these methods either only apply to special cases, are incomplete exhibiting poor image quality and/or scale badly such that only modest scenes can be rendered in real-time with current hardware. The techniques developed in this thesis extend upon earlier research and provide a novel, comprehensive framework for storing global illumination in a data structure - the Virtual Light Field - that is suitable for real-time rendering. The techniques trade off rapid rendering for memory usage and precompute time. The main weaknesses of the VLF method are targeted in this thesis. It is the expensive pre-compute stage with best-case O(N^2) performance, where N is the number of faces, which make the light propagation unpractical for all but simple scenes. This is analysed and greatly superior alternatives are presented and evaluated in terms of efficiency and error. Several orders of magnitude improvement in computational efficiency is achieved over the original VLF method. A novel propagation algorithm running entirely on the Graphics Processing Unit (GPU) is presented. It is incremental in that it can resolve visibility along a set of parallel rays in O(N) time and can produce a virtual light field for a moderately complex scene (tens of thousands of faces), with complex illumination stored in millions of elements, in minutes and for simple scenes in seconds. It is approximate but gracefully converges to a correct solution; a linear increase in resolution results in a linear increase in computation time. Finally a GPU rendering technique is presented which can render from Virtual Light Fields at real-time frame rates in high resolution VR presentation devices such as the CAVETM.

La thèse est consacrée aux méthodes scientifiques de visualisation des champs électromagnétiques dans un environnement tridimensionnel. Les méthodes élaborées concernent trois domaines : la représentation graphique de données scientifiques, l'interaction avec l'utilisateur, la réalisation de la visualisation stéréoscopique. Des méthodes de navigation dans l'espace, de manipulation des objets et du contrôle de l'application stéréoscopique par menus ont été développés. Un scenarii d'interaction et de synchronisation des tâches est également décrit. L'extraction de valeur locales en un point quelconque de la représentation graphique constitue un point fort de la thèse. Cette opération est rendue possible par l'utilisation d'une structure de données originale. Un chapitre est entièrement consacré aux méthode de réalisation d'images stéréoscopiques et à leur recomposition pour obtenir une perception en relief. Les principaux paramètres sont déterminés par une procédure automatique
The thesis is devoted to the methods of electromagnetic fields' scientific visualization set in multidimensional virtual reality environment which gives spatial image and interaction with data space. Developed methods concern three domains: graphical methods of scientific data presentation, human-machine communication and realization of stereoscopy. In order to present volumetric and vector features the standard methods were adopted: colored maps (interactively cutting data set), isosurfaces and cones (vectors). The method of navigation within data space, objects' manipulation and control of application using menu system were developed. The most interesting method is numerical data querying directly from graphical objects realized based on the author's data structures. Much attention was devoted to stereo image creation and its influence on the space perception improvement. The result is the method of stereo parameters' automatic calculation

Ce travail se concentre sur le développement d'une procédure expérimentale d’essai mécanique à haute vitesse de déformation de matériaux. La nouveauté de ce travail est l'utilisation de champs d’accélération mesurés comme cellule de force, évitant la nécessité des mesures des forces externes. Pour identifier les paramètres constitutifs des matériaux testés à partir des mesures de champs, la méthode champs virtuels (MCV) basé sur le principe des puissances virtuelles (PPV) est utilisée. En dynamique, avec la MCV, il est possible de définir des champs virtuels qui mettent à zéro les puissances virtuelles des forces externes. Au lieu de cela, l'accélération obtenue grâce à une double dérivation temporelle des déplacements peut être utilisée comme une cellule de force. Enfin, les paramètres élastiques peuvent être identifiés directement à partir d’un système linéaire qui se construit en réécrivant le PPV avec autant de champs virtuels indépendants que d’inconnues à identifier. Cette procédure est d'abord validée numériquement par des simulations éléments finis puis mise en œuvre expérimentalement en utilisant deux configurations d’impact différentes. Les résultats confirment que effets inertiels peuvent être utilisés pour identifier les paramètres des matériaux sans la nécessité de mesurer la force d’impact, et sans exigence de déformations uniformes comme dans les procédures actuelles basées sur le montage de barres d’Hopkinson. Ces nouveaux développement ont le potentiel de mener à de nouveaux essais standards en dynamique rapide
This work focuses on the development of a novel experimental procedure for high strain rate testing of materials. The underpinning novelty of this work is the use of the full-field acceleration maps as a volume distributed load cell, avoiding the need for impact force measurement. To identify the constitutive parameters of materials from the full-field data, the Virtual Fields Method (VFM) based on the principle of virtual work is used here. In dynamics, using the VFM, it is possible to define particular virtual fields which can zero out the virtual work of the external forces. Instead, the acceleration obtained through second order temporal differentiation from displacement can be used as a load cell. Finally, the elastic parameters can be identified directly from a linear system which is built up through rewriting the principle of virtual work with as many independent virtual fields as unknowns. Thus, external force measurement is avoided, which is highly beneficial as it is difficult to measure in dynamics. This procedure is first numerically validated through finite element simulations and then experimentally implemented using different impact setups. Both results confirm that inertial effects can be used to identify the material parameters without the need for impact force measurements, also relieving the usual requirements for uniform/uniaxial stress in SHPB like test configurations. This exciting development has the potential to lead to new standard testing techniques at high strain rates

Experimental techniques for measuring the mechanical response of rubbers under dynamic loading are developed utilising the virtual fields method (VFM), to inversely identify constitutive behaviour from experimental observations. Rubbers and other 'soft' materials are difficult to characterize using traditional dynamic techniques such as the split Hopkinson bar: the low sound speed makes it difficult to achieve static equilibrium and the small supported forces give low signal-to-noise ratios in the experimental data. In this research, the dynamic VFM with the aid of high-speed imaging is applied to dynamic tensile experiments to resolve these difficulties. The VFM is a mathematical technique that makes use of the principle of virtual work. Manipulation of this equation enables us to remove the need for traditional force measurement, instead exploiting acceleration full-field data as a virtual load cell. Thus, the aforementioned difficulties are no longer of concern: the technique requires that the specimen is not in static equilibrium and that inertial forces are significant compared to material forces. Two dynamic tests and dynamic VFMs are developed and applied to tensile drop-weight and gas-gun driven experiments. The first uses small amplitude dynamic deformation superposed on static pre-stretching. Dynamic identifications at a number of pre-strains are collated to identify the complete nonlinear behaviour. The second utilizes a large strain amplitude of dynamic loading: one experiment characterizes the full response. Further applications of the dynamic VFM are explored in order to improve the first method and to extend the identification capability, and experiments performed at non-ambient temperatures allow a preliminary exploration of time-temperature superposition.

In this thesis I cover the theoretical framework and the practice based implications of bringing the fundamental principles of a cybernetic art educational strategy, the Groundcourse, which was developed and taught during the 1960’s in England by Roy Ascott, into the virtual, three dimensional builder’s world of the metaverse; to be implemented there as a non-institutional, voluntary, self-directed, adult oriented learning system for avatars – one which is expected to be taught by avatar instructors who will formulate the specifics of their curriculum and their methods based upon the cardinal tenets of the Groundcourse, which have been summarized by Roy Ascott as a flexible structure, “within which everything can find its place, and every individual his way,” which would give dimension and substance to the will to create and to change. In order to be able to set the groundwork for the adaptation of the Groundcourse’s principles to my model I have conducted literature reviews in experiential learning theories, with an emphasis on self-directed learning; as well as cybernetic learning. These I have combined with a survey of play theory and virtual world studies, particularly those focusing upon the avatar and metaverse creativity. From all of these I have woven together a foundation which I have combined with a visual documentation which may serve as case studies for my proposal. The new knowledge embodied through this thesis is a learning system for the creative fields that is designed specifically for the residents of online virtual worlds, and yet has its foundations in an earlier, well established and well regarded model.

This is a study of the social dynamics of the current Chinese migrant community in New Zealand through a critical analysis of the Auckland-based Chinese-language media. It combines two research fields, international migration studies and media studies, to conceptualise Chinese-language media as a specific type of alternative media in contemporary New Zealand. The Chinese population in New Zealand has rapidly increased through immigration since the passage of the 1987 Immigration Act; Chinese now comprise 3.4% of the New Zealand population, and a wide variety of Chinese-language media have accordingly thrived in New Zealand. In contrast to New Zealand mainstream media, these Chinese media serve the specific needs and interests of newly arrived and only minimally acculturated Chinese migrants. The research was conducted in three phases: quantitative and qualitative data were acquired from the content of Chinese-language media during the period of the 2005 New Zealand general election; qualitative data were obtained from focus groups and interviews with members of the Chinese audience subsequent to the election; qualitative data were generated from Chinese media personnel. The findings suggest that these Chinese-language media closely reflect and depict recent PRC Chinese migrants’ perceptions of New Zealand and aspirations towards their new life in the host country. Within the global context of the Chinese diaspora in historical and contemporary times, this research also introduces a new angle for exploring the socio-economic impacts of China as a rising superpower on New Zealand and the Pacific Rim.

In the current agricultural context, agricultural machine unproductivity on fields and their impacts on soil along pathways are unavoidable. These machines have direct and indirect costs associated to their work in field, with non-productive time spent in manoeuvres when these are reaching field borders; likewise, there is a double application of product when machines are covering headlands while adding farm inputs. Both issues aggravate under irregular field geometry. Moreover, unproductive time can also appear in operations of loading/offloading the machine\'s reservoir with inputs/harvested-goods, which can increase with an improper use of the reservoir due to the inadequate machine path length. On the other hand, irregular steep surfaces present a problem for establishment of row crops and machine paths towards erosion. Though contouring (i.e., performing field operations perpendicular to slope direction) is a common practice to reduce runoff and increase water infiltration, still elevation contours are never parallel, while machine operations always are. Many of these issues were target for optimization in computer path planning for agricultural machines, where unproductivity was overall minimized and attempts of soil loss reduction by more proper path establishment also yielded results. This thesis gathered these issues in a combined path planning approach making possible to address soil loss and unproductive costs to their proper location. A number of methods was proposed and modified: creating and replicating steerable machine track; finding more optimal references for path coverage on irregular surfaces (curved or straight); quantifying the impacts of soil loss for a given path pattern; identifying spatially the water flow and concentration; defining geometrically different manoeuvre types and calculate its time, space and energy demands; obtain the overlapped area of input application; and quantifying the machine replenishment cost in relation to underuse of its reservoir for following tracks of inadequate length. An algorithm-application was achieved, which is capable of simulating a large number of path coverage scenarios and to display optimized ones based on a user defined criteria. Sugarcane crop, grown in Brazilian conditions, was the main object of study in this thesis because of its high in-field mechanization costs (along with unproductive operational costs), high susceptibility of soil erosion in its planting phase, and for occupying an area of predominant rolling surface. Case studies were subject to this algorithm that provided suitable outputs with minimized impacts. The outputs of the algorithm were comprehensive and showed potential for the methods to be used by agricultural decision makers.
No contexto agrícola atual, improdutividade de máquinas agrícolas em campo e seus impactos sobre o solo ao longo de suas vias são inevitáveis. Estas máquinas têm custos diretos e indiretos associados ao seu trabalho no campo, como tempo improdutivo gasto em manobras quando estes atingem os limites do talhão. Também nestes limites, há uma dupla aplicação de insumos agrícolas quando as máquinas estão cobrindo cabeceiras. Ambas as questões se agravam em talhões de geometria irregular. Além disso, o tempo improdutivo também pode aparecer em operações de carga / descarga do reservatório da máquina com insumos / bens colhidos, o que pode aumentar com um uso indevido do reservatório da máquina devido ao comprimento inadequado do percurso em campo. Ainda, superfícies irregulares e íngremes apresentam um problema para o estabelecimento de culturas em fileira e caminhos de máquinas contra declive. Apesar de operações em nível serem uma prática comum para reduzir o escoamento e aumentar a infiltração de água, curvas de nível nunca são paralelas, enquanto operações agrícolas são sempre paralelas. Muitas destas questões foram alvo de otimização computacional para planejamento de percursos de para máquinas agrícolas, onde a ineficiência foi, em geral, minimizada e tentativas de redução da perda de solo estabelecimento de percursos mais adequados também produziu resultados. Esta tese reuniu estas questões em uma abordagem de planejamento de percurso quantificando e direcionando custos de perda de solo e improdutividade de máquinas para sua devida localização. Métodos foram propostos e modificados, como: criar e replicar trajetos transitáveis de máquinas; encontrar referências ideais para a cobertura do trajeto em superfícies irregulares (curvas ou retas); quantificação dos impactos da perda de solo por um determinado padrão de percursos; identificar espacialmente o fluxo da água e sua concentração; definir geometricamente diferentes tipos de manobras e calcular o seu tempo, espaço e energia demandada; obter a área sobreposta de aplicação de insumos; e quantificar custo de reposição da máquina em relação à subutilização de seu reservatório para seguir trajetos de comprimento inadequado. Um aplicativo-algoritmo foi obtido capaz de simular um grande número de cenários de padrões de percurso, e exibindo aqueles que foram otimizados por critérios definidos pelo usuário. A cultura da cana, em condições brasileiras, foi a principal cultura de estudo nesta tese devido ao seu alto custo de mecanização (assim como custos operacionais improdutivos), alta suscetibilidade à erosão do solo na sua fase de plantio, e ocupando predominantemente áreas de superfície irregular. Os estudos de caso foram sujeitos ao algoritmo que obteve resultados coerentes e impactos minimizados. Os resultados do algoritmo mostram potencial para que os métodos avaliados sejam utilizados por tomadores de decisão da área agrícola.

This thesis investigates the flow field of a twin-engine, medium lift utility helicopter numerically. The effects of the exhaust hot gases emerging from the engines are accounted for in the numerical study. The commercial computational fluid dynamics (CFD) software ANSYS Fluent is employed for the computations. While the effects of engines are included in the computations through simple inlet and outlet boundary conditions, the main and tail rotors are simulated by the Virtual Blade Model in a time-averaged fashion. Forward flight at four different advance ratios and hover in ground effect are studied. The temperature distribution around the tail boom is compared to available flight test data. Good agreement with the flight test data is observed.

Qui n’a jamais souhaité avoir des yeux derrière la tête ? Cette thèse propose d’étudier l’extension du champ visuel humain, que ce soit dans le monde réel ou dans un environnement virtuel. Nous avons d’abord conçu FlyVIZ, un dispositif qui permet d’augmenter le champ visuel. Il est composé d’une caméra catadioptrique, d’un visiocasque et d’un algorithme de traitement d’image. Lorsqu’un utilisateur porte ce dispositif, il dispose d’une vue à 360 degrés de son environnement. Le prototype a été testé avec succès dans différents scenarios, comme attraper un objet tendu dans le dos sans tourner la tête, ou passer des portes en marchant à reculons. Ensuite nous avons proposé une nouvelle méthode pour le rendu d’environnements virtuels, avec un champ visuel étendu, et en temps réel. Pour résoudre les problèmes dus à l’utilisation de projections non planes, nous avons ajouté une nouvelle étape dans le pipeline graphique. Notre méthode a ensuite été adaptée au rendu stéréoscopique avec un champ visuel de 360°. Nous avons mené une évaluation préliminaire sur l’utilisation d’un champ visuel étendu appliqué à une tache de navigation dans des environnements virtuels. Nos résultats semblent confirmer que l’utilisation d’un champ visuel étendu permet une navigation plus efficace, en diminuant le temps moyen pour effectuer une tache. Parmi les différentes projections non planes testées, une préférence pour les projections équirectangulaire et de Hammer a été exprimée. Nous avons également traité le problème de conflit d’indice de profondeurs rencontré dans les images stéréoscopiques lorsqu’un objet affiché en parallaxe négative est partiellement occulté par un bord du support d’affichage. Nous avons proposé SCVC (Stereoscopy Compatible Volume Clipping, le découpage de la scène selon le volume compatible avec la stéréoscopie) pour résoudre ce problème en n’affichant que la partie de l’espace qui n’est pas sujette au conflit d’indice de profondeur. La méthode a été évaluée et les résultats ont montrés que SCVC améliore significativement la perception de la profondeur et que les utilisateurs expriment une préférence pour cette méthode. L’extension du champ visuel humain ouvre de nouvelles perspectives pour l’exploration ou la surveillance de l’environnement d’un utilisateur. Cette extension pourrait bénéficier à diverses applications, que ce soit dans le contexte d’un environnement réel ou virtuel. Pour la sécurité des personnes ou la défense, des pompiers, des policiers ou des soldats pourraient tirer avantage d’un champ visuel étendu. Ce type de visualisation peut également profiter à l’exploration rapide d’environnements virtuels ou à la recherche d’objet dans ces derniers
Who have never wanted to have eyes in the back of his head? This doctoral thesis proposes to study the extension of the human field-of-view (FoV) in both real and virtual environments. First we have designed FlyVIZ, a new device to increase the human FoV. It is composed of a helmet, combining a catadioptric camera, a HMD and an image processing algorithm. Wearing this device allows a user to experience 360° vision of its surroundings. The prototype is demonstrated through scenarii such as grasping an object held out behind their back without turning their head or walking backward through doorways. Then we have proposed a novel method to render virtual environments with wide FoV in real-time. To solve the rendering issue induced by usage of non-planar projections, we introduce a special stage in real-time rendering pipeline. Our method was then adapted for real-time stereoscopic rendering with 360° FoV. We have conducted a preliminary evaluation of real-time wide FoV rendering for a navigation task in virtual reality. Our results confirm that using a wide FoV rendering method could lead to more efficient navigation in terms of average task completion time. Among the different tested non-planar projection methods, the subjective preference is given to equirectangular and Hammer projections. We also address the problem of frame cancellation, generated by the conflict between two depth cues: stereo disparity and occlusion with the screen border. We have proposed the Stereoscopy Compatible Volume Clipping (SCVC), solving the problem by rendering only the part of the viewing volume free of disparity - frame occlusion conflict. The method was evaluated and results have shown that SCVC notably improved users’ depth perception and that the users expressed preference for SCVC. Wide FoV opens novel perspectives for environments exploration or monitoring. Therefore, it could benefit to several applications, both in real world context or virtual environments. In safety and security applications, firemen, policemen or soldiers could take advantage of wide FoV. Performance of searching task and fast exploration in virtual environments could also be improved with wide FoV

In this work, an inverse approach for the identification of the LR stiffness parameters of maritime pine (P. Pinaster) wood within the stem has been investigated. It is based on the ap- plication of the virtual fields method (VFM) to a rectangular specimen loaded with the Iosipescu fixture. This test has been designed in order to involve several in-plane stiffness components. The displacement fields have been measured by the grid method. The strain fields have been reconstructed from the measured displacement fields using a polynomial approximation scheme. The approach has been validated both numerically and experimentally. Two specimen configurations with grain at 0◦ and 45◦ have been compared. With the 0◦ configuration, only the Q11 and Q66 (longitudinal and shear stiffnesses) parameters have been identified with acceptable dispersion. The grain rotation of 45◦ has generated a redistribution of the strain fields allowing a better iden- tification, namely for the Q22 (radial or transverse stiffness) parameter. The latter has been used in a subsequent study aiming at investigating the radial variability of the stiffnesses within the stem. It has been found that both Q22 and Q66 decrease from the pith to about the middle radius of the stem and increase afterwards to the outmost positions
Dans ce travail, une méthode d'identification des paramètres de rigidité du bois a été étudiée et appliquée à l'essence pin maritime (P. Pinaster) dans le plan LR. Cette approche est basée sur la méthode de champs virtuels (MCV) et sur la mesure de champs de déplacements sur une éprouvette parallélépipédique chargée avec le montage de cisaillement d'Iosipescu. Cet essai a été conçu afin d'activer plusieurs rigidités, générant des champs de déformation non homogènes. Ces champs ont été déduits à l'aide d'une méthode d'approximation polynomiale des champs de déplacement mesurés par la méthode de la grille. Les paramètres constitutifs ont ensuite été déterminés par la MCV. L'approche a été validée numériquement et expérimentalement. Deux configurations d'éprouvette avec le fil du bois orienté à 0◦ et à 45◦ ont été comparées. Avec la configuration à 0◦, seuls les paramètres Q11 et Q66 (rigidités longitudinale et de cisaillement) ont été identifiés avec une dispersion acceptable. L'orientation à 45◦ a introduit une redistribution des champs de déformation permettant notamment une meilleure identification du paramètre Q22 (rigidité radiale ou transverse). Cette dernière configuration a été employée dans une étude concernant la variabilité radiale des rigidités à l'intérieur de la grume de l'arbre. Il a été constaté que Q22 et Q66 diminuent du centre à la moitié du rayon de la grume et augmentent après jusqu'à la périphérie

Virtual Commissioning (VC) enables simulation of the combined work of mechanical, electrical, robot andautomation engineers prior to commissioning of the real production equipment. Hence, testing of areaslike collisions, PLC and robot code can be performed in risk free virtual environments and thus, errorscan be detected and corrected early in the development phase of the production equipment. Effectively,both the time and the cost of commissioning will decrease significantly. In addition, advantages likeoperator training, increased knowledge about the equipment, a more mature and optimized system priorto installation is enabled. Nowadays, the commissioning phase of a production system accounts for 25%of the total project time and research has shown that VC can decrease the commissioning time with upto 75%.However, despite all advantages and existing solutions that enables VC, it is not a standard amongmanufacturing companies nor production equipment providers to use VC today. Therefore, we wantedto investigate why VC is not a standard today.There are many barriers and challenges that must be solved prior to successful implementation of VC. Aglobal survey concerning simulation concluded that eight fields of action must be addressed in order tofacilitate the use of simulation. These eight fields address barriers and challenges and they are assumedto apply for VC too. The fields are categorized into four technical and four non-technical fields of action.The technical concerns: model re-use, modeling efficiency, integration and usability. The non-technicalconcerns: work-flow, education, acceptance and collaboration.The purpose of this project is to investigate barriers that prevent VC from becoming widely used inthe industry. Thus, each field of action was researched to better understand why VC is not commonlyused. In addition, the objective of the project is to provide an investigation regarding the technical andnon-technical fields of actions and how each of the parties along the value chain relate to each field.Therefore, the following research question was formed. What barriers are preventing VC from gainingmomentum and becoming widely used by the industry?Through our interviews we did not find any company that currently use VC.We conclude that it generallyis the non-technical fields of action that contain barriers that prevent VC from becoming a standard inthe industry. Especially, it is the organizational related barriers that are the most severe. Nowadays,there exist technical solutions that enables VC and the technical fields of action mainly treat modelingefficiency improvements. However, interoperability is considered to be the most severe technical barriertowards VC and is therefore an important area to improve. Nonetheless, we conclude that the technicalbarriers are considered less severe compared to the non-technical in terms of enabling VC to becomingwidely used.
Virtuell Idriftsättning (VC) Virtual Commissioning är ett aktuellt tillvägagångssätt som underlättarinstallationen av nya maskiner för producerande företag och därmed hjälper att möta ett tuffare produktionsklimat.VC minskar risken, tiden och kostnaden för idriftsättningsprojekt, eftersom att manknyter ihop olika ingenjörsdiscipliner till en gemensam simuleringsplattform där deras arbete kan valideras.Dessa discipliner gäller primärt, mekanik, el-installation, automation och robotik. Vidare så kanfördelar som operatörsträning, ökad kunskap om utrustning och högre mognadsgrad av optimerade systemvalideras innan installationen av maskinen påbörjas. I dagsläget tar idriftsättningen 25% av dentotala projekttiden och forskning visar på att VC kan minska detta med upp till 75%.Trots att VC innebär många fördelar och att det finns programvaror som möjliggör VC är det idaginte ett etablerat tillvägagångssätt inom industrin. Därför ville vi i vårt examensarbete undersöka deunderliggande anledningarna till detta.Det finns många trösklar och utmaningar som måste lösas innan en lyckad implementering av VC. Medgrunden från en global enkät som undersökte vilka faktorer hindrar simulering från att bli ett standardverktyginom industrin utkristalliserades åtta olika områden, så kallade fields of action. Dessa antas ävengälla för VC och de åtta områdena kan delas upp i fyra tekniska-och fyra icke-tekniska områden. Detekniska områdena berör modellåteranvändning, modelleringseffektivitet, integration och användbarhet.De icke-tekniska områdena berör arbetsmetod, utbildning, acceptans och samarbete.Syftet med denna rapport är att undersöka trösklar som hindrar VC från att bli en standard inomindustrin. De åtta områdena används alltså för att undersöka varför VC inte används. Vidare vardet viktigt för oss att ta reda på hur de olika aktörerna i värdekedjan såg på varje enskilt område.Därför utformade vi följande forskningsfråga. Vilka trösklar begränsar VC från att bli en standard inomindustrin?Det var inget av våra intervjuade företag som använde sig av VC på en vardaglig basis, det var dock någrasom genomförde pilotprojekt. Generellt sätt finns det trösklar till både de tekniska och icke-tekniskaområdena, men flest trösklar är kopplade till de icke-teknisk områdena. Därför är de icke-tekniskaområdena intressanta att åtgärda primärt. Även om det är tekniskt genomförbart att implementeraVC finns det många tekniska trösklar som kan göra att arbetet med simuleringsmodeller underlättar.Vidare är det största tekniska hindret begränsad interoperabilitet mellan programvaror. Det är dock deicke-tekniska områdena som till störst del begränsar VC från att bli en standard inom industrin.

Les travaux de la thèse visent à mettre en place une méthodologie innovante de caractérisation du comportement viscoplastique des matériaux métalliques sous chargement purement inertiel. Sous chargements mécaniques extrêmes (e.g., crash, impact ou explosions), leur comportement mécanique présente en effet pour nombre d’entre eux une sensibilité à la vitesse de déformation. Des approches dites statiquement déterminées sont majoritairement utilisées pour caractériser leur comportement, mais elles requièrent de nombreux essais dont les conditions expérimentales sont souvent contraintes comme par exemple l’homogénéité de la vitesse de déformation qui doit être maintenue constante en temps par exemple. En revanche, des approches dites statiquement indéterminées permettent l’exploitation d’essais mécaniques avec peu d’hypothèses (voire sans) sur les conditions d’essai. Une méthodologie fondée sur un essai d’impact purement intertiel est mise en oeuvre ici pour identifier le comportement viscoplastique de ces matériaux. Avec la Méthode des Champs Virtuels, la méthodologie permet l’identification des paramètres matériaux en exploitant uniquement la mesure des champs de déformation et d’accélération, potentiellement hétérogènes en temps et en espace. Ainsi, celui-ci peut être caractérisé sur une large gamme de déformations et de vitesses de déformation plastiques en procédant à un nombre limité d’expériences. La méthode repose sur le développement d’un simulateur d’images avancé permettant de définir au préalable l’ensemble du dispositif expérimental (géométrie de l’éprouvette et conditions expérimentales). Optimisées numériquement pour prescrire les paramètres d’essai critiques, les réalisations expérimentales menées sur un alliage de Titane utilisé dans l’industrie aéronautique ont permis d’identifier les paramètres d’un modèle de Johnson-Cook sur un spectre de déformations et de vitesses de déformation plastiques pré-déterminé. Les incertitudes de la mesure sont également intégrées et analysées dans ce travail
This thesis aims at developing an innovative methodology for viscoplastic material behaviour characterization of metallic materials under purely inertial loads. Indeed, their mechanical behaviour under extreme conditions (e.g., crash, impact or explosions) is often rate-dependant. Statically determinate approaches are mainly used to characterize their behaviour. However, they require numerous tests for which testing conditions are strongly constrained, such as the strain rate which has to remain constant in time and space for instance. By contrast, statically undeterminate approaches enable test processing with a few (or without) hypotheses on experimental conditions. In this work, the Image-Based Inertial Impact test methodology has been extended to characterize the viscoplastic behaviour of metallic materials. Owing to the Virtual Fields Method, it enables the identification of constitutive material parameters with the sole knowledge of strain and acceleration fields (possibly heterogeneous in time and space). Therefore, constitutive models can be characterized over a wide range of plastic strain and strain rate, while the number of tests is limited. Tests design notably relies on the development of a synthetic images generator to determine the experimental setup (e.g., specimen geometry or testing conditions). Finally, experiments are carried out with optimized test configurations to identify Johnson-Cook parameters over a predicted range of plastic strain and strain rate for a titanium alloy widely used in aerospace industry. Identification uncertainties are also quantified and analysed in this work

Métodos eficientes para planejamento de caminhos têm sido explorados ao longo dos anos para permitir movimento de robôs autônomos ou agentes virtuais. Basicamente, estes algoritmos buscam pelo ambiente por um caminho com pouca probabilidade de colisão com obstáculos, e que conduza o agente de uma posição inicial para uma posição objetivo. Apesar de os primeiros algoritmos para planejamento de caminhos para calcular rotas em grafos foram apresentados a mais de 50 anos atrás, ainda existe muito trabalho sendo realizado para melhorar as técnicas existentes hoje em dia. Os algoritmos de planejamento de caminhos atuais normalmente assumem que o ambiente pode ser facilmente projetado em um plano. Também existem diversos algoritmos que podem trabalhar facilmente com mais dimensões. Porém, uma classe de ambientes que não podem ser facilmente tratadas pelos algoritmos atuais é composta por superfícies arbitrárias. Estas superfícies, com buracos e torções, por exemplo, não podem ser facilmente projetadas em um plano. O fato de o caminho ser restrito à superfície faz com que, em um dado ponto o algoritmo precise calcular um caminho 2D em uma superfície 3D, o que não é trivial de mapear em um algoritmo de planejamento de caminhos para várias dimensões. Este trabalho apresenta uma nova técnica de planejamento de caminhos em superfícies 3D, chamada 3DS-BVP. Este novo planejador de caminhos é baseado em um algoritmo de planejamento de caminhos para ambientes 2D. O algoritmo anterior, chamado BVPPath- Planner, utiliza problemas de valor de contorno (Boundary Value Problems, BVP) e funções harmônicas para gerar campos potenciais. Ao seguir o gradiente descente destes campos potenciais, é possível produzir caminhos suaves livres de mínimos locais, partindo de qualquer posição do ambiente para um dado objetivo. Nosso algoritmo gera um campo potencial diretamente na superfície 3D utilizando um método numérico que foi inspirado por aquele utilizado no BVP-Path-Planner. O 3DS-BVP trabalha sobre superfícies complexas com buracos ou curvaturas, representadas por malhas de triângulos, sem a necessidade de parametrizar a superfície em uma representação 2D. Nossos resultados demonstram que a técnica pode gerar caminhos com qualidade similar àqueles gerados pelo BVP-Path-Planner em ambientes planos. O mesmo algoritmo é capaz de gerar caminhos em superfícies arbitrárias a taxas de atualização interativas.
Efficient path planning methods are being explored along the years to allow the movement of autonomous robots or virtual agents. Basically these algorithms search the environment for a path with low probability of collision with obstacles that conduces the agent from an initial to a goal position. Although the first path planning algorithms to compute routes in graphs were presented more than 50 years ago, there is still a lot of effort into improving the current approaches. The current path planning algorithms usually assume that the environment can be easily projected on a plane. There are also other algorithms that can easily deal with higher dimensional spaces. But a class of environments that cannot be easily treated by current algorithms is the one composed by arbitrary surfaces. These surfaces, with holes and bends for instance, cannot be directly projected on a plane. Because the path must be on the surface, it has only 2 degrees of freedom in any point of the surface, which is not trivial to map for a higher dimensional path planning algorithm. This work presents a new technique for path planning on 3D surfaces called 3DS-BVP. This new path planner is based on a previous path planning algorithm for 2D environments. The former algorithm, called BVP-Path-Planner, uses Boundary Value Problems (BVP) and harmonic functions to generate potential fields. By following the gradient descent of these potential fields, it is possible to produce smooth paths free from local minima from any point of the environment to a given goal position. Our algorithm generates a potential field directly on the 3D surface using a numerical method inspired on the one used by the BVP-Path-Planner. The 3DS-BVP works over complex surfaces of arbitrary genus or curvature, represented by a triangle mesh, without the need of 2D parametrizations. Our results demonstrate that our technique can generate paths with similar quality as those generated by the BVP-Path-Planner in planar environments. The same algorithm is also able to generate paths in arbitrary surfaces at interactive frame rates.

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In the recovering process of oil, rock heterogeneity has a huge impact on how fluids move in the field, defining how much oil can be recovered. In order to study this variability, percolation theory, which describes phenomena involving geometry and connectivity are the bases, is a very useful model. Result of percolation is tridimensional data and have no physical meaning until visualized in form of images or animations. Although a lot of powerful and sophisticated visualization tools have been developed, they focus on generation of planar 2D images. In order to interpret data as they would be in the real world, virtual reality techniques using stereo images could be used. In this work we propose an interactive and helpful tool, named ZSweepVR, based on virtual reality techniques that allows a better comprehension of volumetric data generated by simulation of dynamic percolation. The developed system has the ability to render images using two different techniques: surface rendering and volume rendering. Surface rendering is accomplished by OpenGL directives and volume rendering is accomplished by the Zsweep direct volume rendering engine. In the case of volumetric rendering, we implemented an algorithm to generate stereo images. We also propose enhancements in the original percolation algorithm in order to get a better performance. We applied our developed tools to a mature field database, obtaining satisfactory results. The use of stereoscopic and volumetric images brought valuable contributions for the interpretation and clustering formation analysis in percolation, what certainly could lead to better decisions about the exploration and recovery process in oil fields
No processo da recupera??o do petr?leo, a heterogeneidade das rochas exerce um impacto enorme na forma como os l?quidos se movem no reservat?rio, definindo quanto petr?leo pode ser recuperado. A fim de estudar esta variabilidade, a teoria da percola??o, que descreve fen?menos envolvendo geometria e conectividade ? um modelo muito ?til. Os resultados da simula??o de percola??o s?o de car?ter tridimensional e n?o t?m nenhum significado f?sico at? que sejam visualizados em imagens ou anima??es. Embora ferramentas poderosas e sofisticadas de visualiza??o tenham sido desenvolvidas, estas transformam grandes volumes de dados em imagens 2D. A fim de interpretarmos os dados como eles aparecem no mundo real, t?cnicas de realidade virtual baseadas principalmente em estereoscopia podem ser usadas. Neste trabalho, propomos uma ferramenta interativa, denominada ZSweepVR, baseada em t?cnicas de realidade virtual, que permite uma melhor compreens?o dos dados volum?tricos gerados por simula??es de percola??o din?mica. O sistema desenvolvido tem a capacidade de renderizar imagens utilizando duas t?cnicas diferentes: renderiza??o de superf?cie e renderiza??o de volumes. A renderiza??o de superf?cie ? realizada utilizando diretivas OpenGL, enquanto que a renderiza??o volum?trica ? realizada pelo algoritmo de renderiza??o volum?trica direta ZSweep. No caso da renderiza??o volum?trica, implementamos algoritmo para gerar imagens est?reo. N?s tamb?m propomos melhorias no algoritmo original de percola??o din?mica visando melhorar sua efici?ncia. Aplicamos as ferramentas desenvolvidas a dados de campos maduros, obtendo resultados satisfat?rios. O uso de imagens estereosc?picas e volum?tricas trouxe contribui??es valiosas para a interpreta??o e analise da forma??o dos aglomerados na percola??o, o que certamente pode levar a decis?es melhores sobre a explora??o e recupera??o de petr?leo

The aim of the Master’s Thesis work is to study and develop algorithms for autonomous travel of a UGV (Unmanned Ground Vehicle). A vehicle for the mounting of sensors has been constructed in order to perform the work. Since the UGV is to be used outdoor in urban areas, GPS can be used. To improve precision and robustness, inertial navigation is used in addition to GPS, since GPS reception is likely to be diminished in such areas. The sensors used for navigation are consequently GPS, magnetometers, accelerometers, gyroscopes, tachometers and ultra sonic sensors measuring distance to be used in detection of obstacles. The system has been implemented in Matlab. Two alternative methods of navigation with sensor fusion have been developed; one is a decentralized method with Kalman filtering using an error model and the other is a centralized particle filter using an all-embracing model of the vehicle. The two methods have been evaluated and compared. Test results show that the two methods perform equivalently.

The autonomous travel is undertaken between predetermined waypoints. In order to steer the vehicle a PID-controller based on the error between heading and its reference value is used. The computation of the reference value is based on position and heading in comparison to the desired path. The system has been tested using different routes and the results show an evident improvement of the precision in navigation compared to using only GPS-data. This holds for both navigation methods. Simulation of collision avoidance using virtual force fields shows satisfying results as well as terrain navigation with coordinate map referencing.

Examensarbetet är en studie i utveckling av algoritmer för autonom förflyttning av en UGV (eng Unmanned Ground Vehicle). För ändamålet har en farkost konstruerats där budgetsensorer för navigering används. Farkosten är tänkt att färdas utomhus i tätbebyggt område och GPS används. För förbättring av noggrannhet och robusthet vid dålig GPS-mottagning används även sensorer för tröghetsnavigering vilket här innebär magnetometrar, accelerometrar, gyron och tachometrar. För hinderdetektering finns avståndsmätande ultraljudssonar. Systemet som tagits fram har implementerats i realtid i Matlab. Två olika navigeringsmetoder med sensorfusion har utprovats; en decentraliserad variant med kalmanfilter som är uppbyggd kring felmodeller och en centraliserad variant med ett partikelfilter som använder en helhetsmodell för farkosten. De båda navigeringsmetoderna har utvärderats och jämförts. Resultat visar att de båda metoderna presterar likvärdigt.

Den autonoma förflyttningen utförs mellan förutbestämda brytpunkter. För att styra farkosten har en PID-regulator baserad på felet mellan kurs och börvärde använts. Börvärdet på kurs baseras på nuvarande position och riktning relativt den önskade färdvägen. Olika körsituationer har testats och resultaten visar en markant förbättring av navigeringsprecisionen jämfört med endast GPS-mätningar för både kalman- och partikelfilter. Simuleringar på vektorfältsstyrning med virtuella kraftfält för att undvika hinder har utförts med goda resultat liksom simuleringar av kartreferenspositionering.

[ES] La neurociencia es un campo que abarca muchas especialidades. El objetivo de esta tesis es subsanar algunas carencias tecnológicas que existen en los métodos actuales de experimentación animal en neurociencia. En esta tesis, se presentan seis proyectos, que tendrán como objetivo mejorar el "Principio de las tres R", el cual fue enunciado por los biólogos ingleses W. M. S. Russell y R. L. Burch, durante la experimentación animal. El comportamiento es uno de los aspectos más importantes de la vida animal. Depende de los vínculos entre los animales, sus sistemas nerviosos y sus entornos. Para estudiar el comportamiento de los animales de laboratorio, se necesitan varias herramientas, pero una herramienta de seguimiento es esencial para llevar a cabo un estudio de comportamiento exhaustivo. Varias herramientas de seguimiento visual están actualmente disponibles. Sin embargo, todas tienen algunos inconvenientes. Por ejemplo, en una situación en la que un animal está dentro de una madriguera o cerca de otros animales, las cámaras de rastreo (tracking) no siempre pueden detectar la ubicación precisa o el movimiento del animal. Por esta razón, los entornos enriquecidos para intentar recrear el hábitat natural de los animales en experimentación no pueden utilizarse, ya que los datos recopilados son insuficientes/inexactos. Con la finalidad de mejorar los experimentos de tracking RFID Assisted Tracking Tile (RATT) es presentado en esta tesis. RATT es un sistema de seguimiento basado en tecnología de identificación pasiva de radiofrecuencia (RFID) y está compuesto por baldosas electrónicas con las que se puede construir una gran superficie, sobre la cual los animales pueden moverse libremente. Esto permite la identificación más precisa de los animales, así como el seguimiento de sus movimientos. Este sistema, que también se puede combinar con un sistema de seguimiento con cámaras, allana el camino para estudios completos de comportamiento en entornos enriquecidos. Dada la capacidad de rastrear animales y, por lo tanto, realizar experimentos de comportamiento exhaustivos, es posible observar cómo se comportan los sujetos desde un punto de vista externo. Sin embargo, si queremos comprender lo que sucede en el cerebro de estos sujetos, es necesario aplicar otras técnicas de análisis, por ejemplo, el estudio de señales dependientes del nivel de oxígeno en la sangre (BOLD, por sus siglas en inglés). Las señales BOLD se basan en las respuestas vasculares a la activación neuronal y se utilizan ampliamente en estudios de investigación clínicos y preclínicos. En entornos preclínicos, los animales suelen ser anestesiados. Sin embargo, los anestésicos causan cambios en la fisiología de los animales, p. Ej. hipotermia, y esto tiene el potencial de alterar las señales funcionales de MRI (fMRI). Para evitar la hipotermia en roedores anestesiados, se presenta TherMouseDuino. Este es un sistema de control automático de temperatura de código abierto, que reduce las fluctuaciones de la temperatura, lo que proporciona condiciones sólidas para realizar experimentos de resonancia magnética funcional. En los cursos de biología y neurociencia, la anatomía del cerebro se enseña generalmente utilizando imágenes de resonancia magnética (IRM) o secciones histológicas de diferentes planos. Estos muestran las áreas macroscópicas más importantes en el cerebro de un animal. Sin embargo, este método no es dinámico ni intuitivo. En esta tesis se presenta un cerebro de rata impreso en 3D con fines educativos. La manipulación manual de la estructura, facilitada por la ampliación de sus dimensiones, junto con la capacidad de desmontar el "cerebro" en algunas de sus partes principales, facilita la comprensión de la organización 3D del sistema nervioso. Este es un método alternativo y mejorado para enseñar a los estudiantes en general y a los biólogos, en particular, la anatomía del cerebro de rata.
[CAT] La neurociència és un camp que abasta moltes especialitats. L'objectiu d'aquesta tesi és esmenar algunes manques tecnològiques que existeixen en els mètodes actuals d'experimentació animal en neurociència. En aquesta tesi, es presenten sis projectes, que tindran com a objectiu millorar el "Principi de les tres R", el qual va ser enunciat pels biòlegs anglesos W. M. S. Russell i R. L. Burch, durant l'experimentació animal. El comportament és un dels aspectes m'és importants de la vida animal. Depèn dels vincles entre els animals, els seus sistemes nerviosos i els seus entorns. Per estudiar el comportament dels animals de laboratori, es necessiten diverses eines, però` una eina de seguiment és essencial per a dur a terme un estudi de comportament exhaustiu. Diverses eines de seguiment visual estan actualment disponibles. No obstant això, totes tenen alguns inconvenients. Per exemple, en una situació en la qual un animal esta` dins d'un cau o prop d'altres animals, les cambres de rastreig (tracking) no sempre poden detectar la ubicació precisa o el moviment de l'animal. Per aquesta raó, els entorns enriquits per a intentar recrear l'hàbitat natural dels animals en experimentació no poden utilitzar-se, ja que les dades recopilades són insuficients/inexactes. Amb la finalitat de millorar els experiments de tracking/seguiment RFID Assisted Tracking Tile (RATT) és presentat en aquesta tesi. RATT es un sistema de seguiment basat en tecnologia d'identificació passiva de radiofreqüència (RFID) i esta` compost per rajoles electròniques amb les quals es pot construir una gran superfície, sobre la qual els animals poden moures lliurement. Això permet la identificació més precisa dels animals, així com el seguiment dels seus moviments. Aquest sistema, que també es pot combinar amb un sistema de seguiment amb cambres, aplana el camí per a estudis complets de comportament en entorns enriquits. Donada la capacitat de rastrejar animals i, per tant, realitzar experiments de comportament exhaustius, és possible observar com es comporten els subjectes des d'un punt de vista extern. No obstant això, si volem comprendre el que succeeix en el cervell d'aquests subjectes, és necessari aplicar altres tècniques d'anàlisis, per exemple, l'estudi de senyals dependents del nivell d'oxigen en la sang (BOLD, per les seues sigles en anglès). Els senyals BOLD es basen en les respostes vasculars a l'activació neuronal i s'utilitzen àmpliament en estudis d'investigació clínics i preclínics. En entorns preclínics, els animals solen ser anestesiats. No obstant això, els anestèsics causen canvis en la fisiologia de els animals, per exemple hipotèrmia, i això te el potencial d'alterar els senyals funcionals de MRI (fMRI). Per a evitar la hipotèrmia en rosegadors anestesiats, es presenta TherMouseDuino. Aquest és un sistema de control automàtic de temperatura de codi obert, que redueix les fluctuacions de la temperatura, la qual cosa proporciona condicions solides per a realitzar experiments de ressonància magnètica funcional. En els cursos de biologia i neurociència, l'anatomia del cervell s'ensenya generalment utilitzant imatges de ressonància magnètica (IRM) o seccions histològiques de diferents plans. Aquests mostren les àrees macroscòpiques més importants en el cervell de un animal. No obstant això, aquest mètode no és dinàmic ni intuïtiu. En aquesta tesi es presenta un cervell de rata imprès en 3D amb finalitats educatius. La manipulació manual de l'estructura, facilitada per l'ampliació de les seues dimensions, juntament amb la capacitat de desmuntar el "cervell" en algunes de les seues parts principals, facilita la comprensió de l'organització 3D del sistema nerviós. Aquest és un mètode alternatiu i millorat per a ensenyar a els estudiants en general i als biòlegs, en particular, l'anatomia del cervell de rata.
[EN] Neuroscience is a field that covers many specialties. The objective of this thesis is to correct some technological deficiencies that exist in current methods of animal experimentation in neuroscience. In this thesis, six projects are presented, which will aim to improve the "Principle of the three Rs" in animal experimentation enunciated by the English biologists W. M. S. Russell and R. L. Burch. In the present era of impressive progress in neuroscience, it is still not arguable that a complete understanding of the brain cannot be possible without a comparable understanding of animal behavior. In order to study the behavior of laboratory animals, various tools are needed, being a reliable tracking system one of the most important to follow large populations of individual subjects that interact in complex manners. Several visual tracking tools are currently available. However, they all have some drawbacks. For example, in a situation where an animal is inside a cave, or is in close proximity to other animals, tracking cameras cannot always detect the precise location or movement of the animal. For this reason, environments that have been enriched in order to attempt to recreate the natural habitat of the animals under experiment, cannot be used, as the data gathered is insufficient/inaccurate. In order to improve the current tracking systems , the RATT is presented. RATT is a tracking system based on passive RFID technology and it is composed of electronic tiles. Using several tiles, a large surface area, on which the animals can move freely, can be built. This enables the more accurate identification of the animals, as well as the tracking of their movements. This system, which can also be combined with a visual tracking system, paves the way for complete behavioral studies in enriched environments. Given the ability to track animals and thus conduct thorough behavioral experiments, it is possible to observe how the subjects behave from an external viewpoint. However, if we want to understand what is going on in the brains of these subjects, it is necessary to apply other analysis techniques, for example the study of BOLD signals. BOLD signals are based on vascular responses to neuronal activation and are used extensively in clinical and preclinical research studies. In preclinical settings, animals are usually anesthetized. However, anesthetics cause changes in the physiology of the animals, e.g. hypothermia, and this has the potential to disrupt fMRI signals. In order to avoid hypothermia in anesthetized rodents, TherMouseDuino is presented. This is an Open-Source automatic temperature control system, which reduces temperature fluctuations, thus providing robust conditions in which to perform fMRI experiments. In biology and neuroscience courses, brain anatomy is generally taught using MRI or histological sections of different planes. These show the most important macroscopic areas in an animals' brain. However, this method is neither dynamic nor intuitive. An anatomical 3D printed rat brain with educative purposes is presented in this thesis. Hand manipulation of the structure, facilitated by the scaling up of its dimensions, together with the ability to dismantle the "brain" into some of main its constituent parts, facilitates the understanding of the 3D organization of the nervous system. This is an alternative and improved method for teaching students in general and biologists, in particular, the rat brain anatomy.
This work was supported in part by the Spanish Ministerio de Economía y Competitividad (MINECO) and FEDER funds under grants BFU2015-64380-C2-2-R (D.M.) and BFU2015-64380-C2-1-R, by EU Horizon 2020 Program 668863-SyBil-AA grant (S.C.). S.C. acknowledges financial support from the Spanish State Research Agency, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (ref. SEV-2013-0317) and by a grant “Ayudas para la formación de personal investigador (FPI)” from the Vicerrectorado de Investigación, Innovación y Transferencia of the Universitat Politècnica de València.
Quiñones Colomer, DR. (2019). Developing preclinical devices for neuroscience research in the fields of animal tracking, fMRI acquisition, and 3D histology cutting [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/118795
TESIS

Within constructed spaces our identities are evident in our interaction with objects, language and practice. The spaces that are understood as "virtual" are additions to an environment we have to locate our bodies within. Objects of technology, an engagement with language or a practice of art utilise our bodies as the zero point for experience of space. "Virtual space" is constructed through the use of objects we associate with the idea of "virtual space" such as consoles, computers and phones. The critical evaluation of virtual space has battled with the idea of the "disincarnated" experience of content, where the body is not the starting point. Virtual space is populated by objects that have physical form. Much like the impossibility of a person surviving on information alone it has become evident that the idea of a virtual disembodied utopia must come back down to earth. The discussion of the form of our identity in virtual space has had to redefine what virtual is, and how form can participate in constructing space. The discussion of form has had to contextualise a concrete practice and a beginning point within the body. The ideas and theories of Lakoff and Johnson, Carr, Talbolt, Fei, Dibble, Rendell, Turkle, Barthes, Davies, Sontag, Hockney, and Merleau-Ponty are evidence that there is an embodied point of view and human experience of "virtual" space. This thesis will use concrete spatial strategies of an artistic and auto-ethnographic practice to show that virtual space and the form of identity are concrete components of everyday environments. Form plays pivotal role in deconstructing or constructing space. Through the use of panorama, as an object of technology as well as a strategy, space is constructed using form. The term avatar used to discuss the "form" of identity in virtual spaces, and in particular what we currently recognise as "online" software driven, or connective virtual spaces. I have recognised that virtual space as not separate but augmentative and I will discuss how the avatar has been utilised within my practice to define virtual space as augmentative to everyday spaces.

Pour limiter la pollution sonore et répondre aux exigences des clients, le secteur automobile est contraint pour la prochaine décennie à diminuer drastiquement les émissions sonores de ses véhicules. Le Groupe Moto Propulseur (GMP) constitue l’une des principales sources de bruit et les solutions palliatives couteuses ne permettront plus à terme le passage des normes acoustiques. L’optimisation du comportement vibro-acoustique de telles structures par un travail détaillé de la conception reste le meilleur levier. Dans ce contexte, les ingénieurs sont à la recherche de méthodes expérimentales d’identification et de caractérisation de sources acoustiques particulièrement efficaces et pertinentes. En ce sens, la principale attente est la reconstruction précise des champs acoustiques sur des structures à géométrie complexe en présence d’un environnement industriel contraignant et non contrôlé. Dans la continuité de la méthode u-iPTF (inverse Patch Transfer Functions) précédemment développée, la première partie de ce travail de doctorat s’est attachée à uniformiser le principe du volume acoustique virtuel sur lequel elle repose afin de proposer la formulation d’une méthode alternative, dénommée m-iPTF, dont le principe théorique permet de répondre intégralement au cahier des charges du partenaire industriel. En effet, contrairement à la méthode u-iPTF, la méthode m-iPTF s’affranchit de la mesure des vitesses de particules d’air, encore peu robuste et coûteuse, et utilise uniquement des pressions acoustiques. Une première étude numérique a cadré le domaine de validité et de mise en application de la méthode. Elle a été suivie par trois campagnes expérimentales de complexité croissante dont une application en conditions industrielles standards, celle d’un GMP complet fonctionnant sur banc moteur. L’ensemble de ces études a permis de démontrer l’adéquation de la méthode à un milieu industriel et d’illustrer toutes les potentialités offertes par la reconstruction 3D de champs pariétaux pour l’optimisation de structures complexes (discrimination et hiérarchisation de sources, corrélation et couplage à la simulation numérique...)
To limit the sound pollution and to meet customer requirements, the automotive sector is constrained for the next decade to drastically reduce the noise emissions of its vehicles. The powertrain is one of the main sources of noise and expensive workaround will not be sufficient in the future to meet acoustic standards. The optimization of the vibro-acoustic behavior of such structures by a detailed design work remains the best way. In this context, engineers are looking for an efficient and relevant experimental noise source identification and characterization method. In this sense, the main expectation is the precise reconstruction of all the acoustic source fields on geometrically complex structures and in the presence of a restrictive and uncontrolled industrial environment. In the continuity of the u-iPTF method (inverse Patch Transfer Functions) previously developed, the first part of this PhD work was to standardize the principle of the virtual acoustic volume on which it relies and to propose the development of an alternative method, called m-iPTF, whose theoretical principle allows reaching all the specifications of the industrial partner. Indeed, contrary to the u-IPTF method, the m-iPTF method overcomes the measurement of air particles velocity, expensive and not yet robust, and uses acoustic pressure only. A first numerical study framed the scope of validity and application of the method. It was followed by three experimental campaigns of increasing complexity with a final application in industrial standard conditions, i.e. a powertrain running on a test bench. All these studies have demonstrated the suitability of the method in an industrial environment and illustrated the potential of the 3D reconstruction of parietal fields for the optimization of complex structures (discrimination and ranking of noise sources, correlation and coupling with numerical simulations...)

Il Virtual Fields Method (VFM) è una tecnica di identificazione inversa che permette di calibrare i paramtri di un generico modello costitutivo del materiale, impiegando campi di deformazioni misurati tramite tecniche full-filed. Nel lavoro di ricerca intrapreso, il VFM è utilizzato per la caratterizzazione del comportamento anisotropro del materiale in condizioni di plasticità. Tale aspetto, infatti, è particolarmente rilevante in molte applicazioni industriali come, ad esempio, processi di stampaggio e, più genericamente, di formatura. Dunque, il VFM è utilizzato secondo la sua formulazione per la teoria delle grandi deformazioni. In tali impieghi, l'identificazione dei parametri caratteristici del materiale è realizzata attraverso un processo iterativo; ne consegue che l'algoritmo d'integrazione delle equazioni costitutive adottato ha effetti sostanziali sull'accuratezza dei risultati e sui tempi di calcolo. A tal fine, un nuovo metodo computazionale per la ricostruzione delle tensioni di Cauchy è qui formulato ed analizzato. Grazie alle sue performances computazionali, questo algoritmo, definito Direct Method, costituisce uno degli strumenti fondamentali impiegati nella presente tesi. Il VFM, e più in generale i metodi inversi, permettono di considerare campi di deformazioni eterogenei ai fini dell'identificazione. Questo ha portato allo sviluppo di nuove procedure sperimentali, capaci di raccogliere un gran numero di informazioni sul comportamento del materiale. L'attività di ricerca si è dunque interessata anche dello studio di nuovi protocolli sperimentali, affrontando tre temi principali: l'ottimizzazione di provini per la caratterizzazione del comportamento elasto-plastico di lamiere, la valutazione del campo di deformazione all'interno del materiale a partire da misure di superficie tramite DIC, la caratterizzazione del comportamento lungo lo spessore di laminati sottili. La metodologia seguita si basa sull'impiego di analisi numeriche non-lineari agli Elementi Finiti come strumento di sviluppo e la successiva verifica sperimentale. La parte finale è dedicata all'identificazione dei parametri costitutivi di un modello di plasticità anisotropa complessa, lo YLD2000-2D. I risultati derivanti la calibrazione effettuata con il VFM sono confrontati con la procedura standard, la quale prevede l'impiego di dati da prove uniassiali a tre differenti orientazioni del materiale e relativi alla condizione di equi-biassialità, ottenuta tramite bulge test. Tale attività sperimentale è applicata a due acciai AHSS impiegati nell'industria dell'automotive: il BH-340 ed il TRIP-780.
The Virtual Fields Method (VFM) is an inverse technique that allows to identify the material parameters of a constitutive model using full-field strain data. In this research activity, the VFM is employed to characterize the anisotropic plasticity behaviour of metals. This aspect, in fact, is particularly important in many industrial processes such as sheet metal stamping and metal forming in general. So, the VFM is used accordingly with its formulation for the finite deformation theory. In such application, the identification of material parameters is performed through an iterative procedure; in this, the algorithm for the integration of constitutive equations has significant effects on accuracy and computational time. A fast computational method for stress reconstruction from strain data in general plasticity is formalized and validated. This algorithm, called Direct Method, is implemented in the VFM and will be exploited for all the analysis given below. The VFM, and the inverse methods in general, allow to consider heterogeneous strain fields for the identification, in order to introduce as much informations about the material as possible. This, also, leads to the development on new experimental procedures capable of collecting a large amount of material data. Employing the Digital image Correlation (DIC) as main tool for the full-field measurement, new experimental procedures are proposed, facing such problems as the optimization of specimens for the elasto-plastic behaviour characterization, the evaluation of the volume displacement from surface DIC measurements, the characterization of sheet metals through-thickness behaviour at large strains. The methodology applied relies on both numerical analysis and experimental validation. The last part is focused on the identification of the material parameters of an anisotropic plasticity model, the YLD2000-2D yielding criterion. The results coming from the inverse identification by means of VFM are compared with the standard procedure based on the uniaxial test at three material orientations and the equi-biaxial stress state by means of bulge test. This experimental investigation is extended on two AHSS steels, the BH-340 and TRIP-780, widely employed in automotive applications.

The first three chapters of this thesis have been devoted to the theoretical background. We presented the novel work of this thesis in chapters 4 and 5. In chapter 4 we have constructed a Chiral effective field theory for the nucleon--nucleon system which contains dibaryon fields as fundamental degrees of freedom. The large scattering lengths in the 1S0 and the 3S1 channels force the dibaryon residual masses to be much smaller than the pion mass. Since no counterterm has to be enhanced like in the KSW approach, naïve dimensional analysis is sufficient to assess the size of the effective field theory low--energy constants, keeping the perturbative expansion under control. We organized the calculation in a series of effective theories, which are obtained by sequentially integrating out higher energy and momentum scales. We first integrate out energy scales of the order of the pion mass. This leads to an effective theory with dibaryon and nucleon fields, pNNEFT. For three momenta much smaller than the pion mass, it is convenient to further integrate out three momenta of the order of pion mass, which leads to the npNNEFT. We have calculated the nucleon--nucleon scattering amplitudes for energies smaller than the pion mass in the 1S0 and the 3S1-3D1 channels at NNLO. The numerical results for the phase shifts and mixing angle are also similar to the ones obtained in the KSW approach. A good description of the 1S0 channel is obtained, but for the 3S1-3D1 channel our results also fail to describe data. The reasons of this failure can be traced back to the iteration of the one potential pion exchange potential. We have calculated the matching of the dibaryon residual masses and dibaryon-nucleon couplings up to NLO. We have showed that, certain class of diagrams that contribute to the residual mass, involving n potential pion exchanges in loops with radiation a pion, have to be summed in the 3S1 channel. In the 3S1 channel the resummation can be carried out. However in the 1S0 channel the resummation is not possible, but it is very likely that loop contributions are still large. Using the results for the matching for residual masses and dibaryon--nucleon coupling for npNNEFT we have given Chiral extrapolation formulas for scattering lengths of the scalar channels up to corrections of order mq(3) We have fitted these expressions to lattice data and compared the results to previous studies of the quark mass dependence of the scattering lengths. In chapter 5 we have considered the possibility that the spectrum of QCD in the Chiral limit contains an isosinglet scalar with a mass much lower than the typical hadronic scale, and have constructed the corresponding effective theory that includes it together with the standard pseudo-Goldstone bosons, ChiPTs. In the purely scalar sector of the theory we argued that the scalar self interactions can be ignored. Demanding that the scalar does not mix with the vacuum together with Chiral symmetry imposes that two of the low--energy constants should be taken as zero. We have presented the calculation of pion mas and decay constant at NLO. The dynamical scalar field introduces new non-analyticities in the quark mass dependence of these observables. We have used lattice data from the ETM collaboration to fit the low--energy constants. The chi-squared per degree-of-freedom delivered by the ChiPTs fits are similar to ChiPT ones indicating that lattice data does not favor any of the theories over the other. The ChiPTs expressions for the S-wave pion-pion scattering lengths differ from those of ChiPT already at leading order. Furthermore ChiPTs allows for the calculation of the sigma decay width. Neither the value of the scattering lengths for the I=0 and I=2 channels are close to the experimental numbers. Although the value of I=0 is slightly closer to it than the one obtained in tree-level ChiPT, the value of the I=2 channel is much further away. We argue, using the decoupling limit that this is due to the sizable NLO corrections because of the large value of l1. We also show a different approach in which we fit the scattering length expressions with all parameters free to lattice data and use the results to provide predictions for the sigma mass and decay width.
En el marc de teories efectives per a Cromodinàmica Quàntica a baixes energies, una situació interessant es presenta quan els graus de llibertat de baixes energies poden formar estats lligats, estats virtuals o ressonàncies pròximes al llindar. Com que aquest estats estan a prop del llindar afecten a les amplituds de dispersió, però tan mateix no poden ser descrites utilitzant teoria de pertorbacions, ja que les series polinòmiques finites en el moment no poden generar un pol en l’amplitud. Aquest pols es poden obtenir resumant certes classes de diagrames, per exemple usant tècniques d’unitarització, que no són consistents amb el comptatge de la teoria efectiva, o alternativament assumint un augment de l’importància de certs acoblaments. En aquest últim cas s’han de calcular les equacions del grup de renormalització per a tots els acoblaments per tal de determinar-ne el tamany correcte, el que dificulta mantenir la sèrie pertorbativa sota control. És una vella observació de Weinberg que la inclusió explícita d’estats lligats i ressonàncies com a graus de llibertat de la teoria efectiva millora la convergència de la teoria de pertorbacions. Es pot entendre fàcilment aquesta millora de la convergencia ja que les amplituds de dispersió tindran la estructura analítica correcta. Un dels temes principals d’aquesta tesi ha sigut explorar aquest fet dins d'un marc modern de teories efectives. El treball original d’aquesta tesi és als capítols 4 i 5. Al capítol 4 hem construït una teoria efectiva Quiral pel sistema nucleó–nucleó que conté camps dibariònics com a graus de llibertat fonamentals. Les longituds de dispersió grans en els canals 1S0 i 3S1 poden ser representades de forma natual gràcies a les petites masses residuals dels dibarions. Em calculat les amplituds de dispersió per aquesta teoria fins a NNLO per als canals 1S0 i 3S1-3D1, i em donat fòrmules d'extrapolació quiral per a les longituds de dispersió d'ona S fins a NLO. Al capítol 5 hem considerat la possiblitat de que l’espectre de QCD en el limit Quiral contingui un isosinglet escalar amb massa molt mes petita que l’escala hadroníca típica, i hem construït una teoria efectiva que l’inclou conjuntament amb els pseudo–bosons de Goldstone. Hem calculat la massa i la constant de decaïment del pion fins a NLO i hem ajustat els resultats a dades en el reticle. També hem estudiat les longituds de dispersió de les col•lisions pió-pió per a ona S en isospin I=0 i I=2 i les hem comprat amb dades al reticle.

Le développement de nouveaux matériaux alliant résistance mécanique et légèreté est un enjeu d'actualité dans de nombreux secteurs industriels. Afin de pouvoir utiliser ces matériaux, il est nécessaire de connaître leurs propriétés mécaniques. Pour les déterminer, des méthodes inverses analysant le comportement vibratoire de la structure peuvent être utilisées. Dans ce travail de thèse, deux méthodes sont utilisées : la Résolution Inverse (RI) et la Méthode des Champs Virtuels (MCV). Dans un premier temps, les méthodes sont appliquées avec la déflectométrie optique, une méthode de mesure plein champ. L'utilisation de cette méthode de mesure avec les deux méthodes inverses permet d'obtenir des cartographies précises de la rigidité de flexion et de l'amortissement de la structure étudiée. La déflectométrie optique mesure les pentes du champ de déplacement. Une opération de gradient inverse permet de remonter au champ de déplacement. Afin de supprimer cette opération, le développement de formalismes sur les pentes de RI et de la MCV est proposé. Ces formalismes sont testés avec des simulations numériques puis une étude expérimentale est présentée. Dans un second temps, une variante de la MCV est développée. Cette variante a pour but d'appliquer la méthode en hautes fréquences où RI et la MCV ne sont plus applicables. La Résolution Inverse Corrigée est une variante de RI qui a pour but d’appliquer la méthode dans les hautes fréquences. La variante de la MCV qualifiée de Méthode des Champs Virtuels Adaptée en Fréquence consiste à déterminer à chaque fréquence la taille de l’intervalle d’intégration des intégrales du Principe des Travaux Virtuels (une forme faible de l'équilibre local sur laquelle se base la MCV). Elle est développée pour la poutre d'Euler-Bernoulli et la plaque de Love-Kirchhoff et est testée sur des données expérimentales pour identifier la rigidité de flexion complexe d'une plaque amortie localement
The development of new materials combining mechanical strength and lightness is a major issue in many industrial sectors. In order to use these materials, it is necessary to identify their mechanical properties. Inverse vibration methods can be used to determine these properties. These methods analyse the vibratory behaviour of the structure to identify the desired mechanical properties. Two methods are used in this thesis: the Force Analysis Technique and the Virtual Fields Method. They are applied here with the aim of identifying the bending stiffness and damping of a thin Love-Kirchhoff plate or an Euler-Bernoulli beam. First, the methods are applied using optical deflectometry, a full-field measurement method.By combining this measurement method with the two inverse methods, it is possible to obtain accurate maps of the bending stiffness and damping of the structure under study. Optical deflectometry measures the slopes of the displacement field. An inverse gradient operation is used to return to the displacement field. In order to eliminate this operation, the development of slope formalisms for the Force Analysis Technique and the Virtual Fields Method is proposed. These formalisms are tested with numerical simulations to identify the bending stiffness, followed by an experimental study. Secondly, a variant of the Virtual Field Method is developed. The aim of this variant is to apply the method when the number of measurement points per flexural wavelength becomes small. In fact, the Force Analysis Technique and the Virtual Field Method are no longer effective when the number of points per bending wavelength falls below 4. This is because a singularity at the bending wavenumber is present in the responses of the methods in wavenumber space. The Corrected Force Analysis Technique is a variant of the Force Analysis Technique which aims to remove this singularity using corrective factors. The application of these factors enables the method to be applied more effectively when the number of points per wavelength becomes small. A variant of the Virtual Fields Method has been developed for the same purpose. The method performs a local polynomial interpolation of the displacement field. The polynomial obtained is used to calculate analytically the integrals of the Principle of Virtual Work (a weak form of local equilibrium on which the Virtual Fields Method is based). These integrals are calculated locally on a virtual segment for the 1D case or on a virtual window for the 2D case. At each frequency, the length of the segment or window that allows the method to be applied when the number of points per wavelength is low is calculated. This length is referred to as the Frequency Adapted Length. The variant is therefore called the Frequency-Adapted Virtual Field Method. It is developed for the Euler-Bernoulli beam and the Love-Kirchhoff plate and is tested on experimental data to identify the complex bending stiffness of a locally damped plate

This thesis aims to understand and explain the importance that prostitution forums have for the exercise of power and influence in the area of prostitution. It also seeks to clarify how these forums developed and were able to occur within a Swedish context. Sweden was the first country to legislate to criminalise only the buying, but not the sale, of sexual services. Social work provisions aims to get people out of prostitution. The thesis is based on an ethnographic study of the three largest Swedish prostitution forums during a two-year period. The empirical material consists of both quantitative participant and content analysis and field notes from observation of the interactions on the forums. The theoretical framework is based mainly on A Theory of Fields by Neil Fligstein and Doug McAdam. It focuses on the collective action on - and between - fields and how institutions are reproduced and changed.   The results show that most of the content was published by a smaller group of actors. The interaction can be divided into the following subjects: social shims; information; negotiations and rules; advice and support; viewpoints on the forum as well as discussion on prostitution and its regulation. Moreover, the study shows that the forums enabled both sex service providers and sex clients to meet collectively, pursue common interests and discuss which rules should prevail in the prostitution market. Providers also pursued self-organised harm reduction social measures. This form of self-help was also sanctioned by a municipal prostitution unit, which can be interpreted as if it acted in a contrary direction to the government’s prostitution policy. The actors in the forums perceived themselves to be stigmatised by society, where sex service providers to a greater extent than sex clients, described a form of stigma. In the forums they could, however, feel a sense of belonging. The actors perceived themselves to be monitored by the Swedish state and they collectively self-regulated the interaction. Sex service providers and sex clients also co-operated, on occasions, with the Swedish state in order to jointly combat child prostitution, human trafficking and organised crime.

Interest in the area of virtual work continues to increase with articles being written from different disciplinary perspectives - e.g. information systems (IS), management, psychology and transportation. In this paper, we map research on virtual work to (a) understand the intellectual base from which this field has emerged, (b) explore how this field has evolved over time, and (c) identify clusters of research themes that have emerged over time and the relationships between them. Specifically, we use co-citation analysis of research published in all social science disciplines to map the field at three points in time - 1995, 2000 and 2006. Our results show that the field has grown from nine research clusters in 1995 to sixteen in 2006. A comparison across these maps suggests that research in the cluster of "virtual teams" has gained significance even as research within some earlier clusters such as "urban planning and transportation" has lost ground. Our longitudinal analysis identifies relevant concepts, theories and methodologies that have emerged in the field of virtual work. This analysis can help interested researchers identify how they may want to contribute to the field of virtual work - by adding to popular clusters, enriching emerging smaller clusters or by acting as bridges across clusters. (author's abstract)

Children spend a large proportion of their days in obligatory sedentary lessons: with notable consequences to health and educational outcomes. This thesis tested Virtual Field Trips (VFTs) as a new format of physically active lesson: integrating educational, globe-based content on classroom interactive whiteboards with related physical movements. It aimed to assess the feasibility of VFTs in primary school settings, before exploring their potential to increase children’s physical activity, on-task behaviour and student engagement. Firstly, a literature review assessed current understandings of childhood physical activity and sedentary behaviour levels and effects on health and educational outcomes. This review also considered school-based intervention attempts to improve these outcomes and also introduced physically active lessons as novel interventions which integrate physical activity into school lessons. Secondly, a systematic review collated the methods and findings of published physically active lesson interventions. Thirdly, a qualitative study assessed teacher and pupil perceptions of a pilot physically active VFT, with identified considerations from this and the systematic review used to refine VFT development. These revisions were used to develop and test a pilot cluster-randomised controlled trial of VFTs named ‘Virtual Traveller’, featuring a six-week intervention period and three month follow-up. Accelerometer- and observation-assessed physical activity, observed on-task behaviour and questionnaire-assessed student engagement outcomes were measured in this intervention. A full process evaluation of the intervention assessed its delivery and the perceptions of participating teachers and pupils. Results show the Virtual Traveller intervention to have no effect on overall, school day or weekend day activity but to significantly improve children’s lesson time physical activity. On-task behaviour was also significantly improved during Virtual Traveller sessions compared to control lessons. There were no effects of the intervention on self-reported student engagement. Prolonged effects were not seen at three month follow-up for any outcomes. Finally, a discussion reflects on the potential for VFTs as physically active lessons, implications for policy, critiques the thesis and identifies avenues for future research. This thesis presents the first example of a physically active lesson intervention specifically developed to use existing classroom technologies. It provides evidence that VFTs as physically active lessons can be integrated into mainstream teaching to increase lesson time physical activity and on-task behaviour, without detriment to student engagement.

The evolution of the industry, known as industry 4.0, has introduced new technologies such as Virtual Commissioning and Industrial Internet of things. Nowadays, virtual models of automated systems are being created in order to be tested while being built in real life, what includes PLC programs, robots, etc. In order to provide a real behaviour emulation, these virtual models should be as similar to reality as possible. Currently, the components communication in a real system is done through Internet with the use of fieldbuses I/O modules. Right now, these modules are not integrated in the virtual model, as the PLC program returns an error due to the hardware not being found. This implies that the PLC project must be modified, and a workaround must be done in order to connect the I/O cards components of the modules. Furthermore, it means that two PLC projects need to be maintained at the same time, one for the real system and another for the virtual system. In this thesis, a research was done to prove if fieldbuses modules could be emulated, helping to improve Virtual Commissioning. The final goal is to allow a PLC project created for a real system to be run again the corresponding virtual model without any change. To achieve this, a driver able to emulate the communication behaviour of an Ethernet/IP fieldbus module is developed and tested against a real PLC program.

Thesis: S.B., Massachusetts Institute of Technology, Department of Architecture, 2017.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 35).
Virtual reality, or VR, will be the next common medium for digital visualization. The purpose of this thesis is to explore how designers will use and discover new design methods with the representation in virtual reality. How do computational design tools such as CAD and VR, which are digital representations of the physical, affect our designs of physical space? In this thesis, I explore the benefits and shortcomings of VR as a design medium. My first hypothesis claims that VR will excel in representing site context, depth, and scale, in comparison to CAD. The second hypothesis says that VR will encourage a preference for monumentality and open spaces in comparison to a higher packing density of objects in CAD. The third hypothesis claims that designers will prefer 3d models with realistic rendering textures in VR, more so than CAD. The fourth and final hypothesis is that architects, familiar with CAD, can design immersive views just from a 3d omniscient plan without immersion, unlike novices. The first part of the research is the creation of a proof-of-concept virtual reality design review tool that can be integrated easily into existing design practices. The VR tool allows a user to explore their 3d modeled spaces with full locomotion and visually records their experiences in the space. This VR tool integrates virtual reality into the process of iterative design. Through subject testing, we explore our understanding of how our spatial perception interacts with simulated virtual space and thus affects our manners of designing. The results led us to several different conclusions. First, intuitive perception of scale and other spatial relationships is easier in VR. Secondly, VR, despite its intimate relation to the human scale, does not promote a preference for large spaces and monumentality. Thirdly, designers slightly prefer realistic rendering textures in VR. Finally, those with architecture training perform slightly better than novices in visualizing 3d immersive views from plans. This project illustrates where virtual reality's value and flaws as a digital visualization medium. It examines what manner the mode of representation affects and limits the process of designing and making.
by Joie Z. Chang.
S.B.

As the technology develops, the communication infrastructure continues to innovate and increase competitiveness. For companies in a country such as Brazil, communicating virtually may be very beneficial in order to become more efficient, as well as more global. Due to today’s technological development and globalization, virtual teamwork has increased. For virtual teamwork to be successful, the importance of virtual leadership needs to be addressed by the organizations. Thus, the purpose of this study is to investigate leadership in a virtual context with focus on its effect on teamwork in culturally diverse teams. Furthermore, due to its emerging market and economic relevance, this study will examine virtual leaders of multinational companies in Brazil. From our dialogues we found that there is a lack of technological infrastructure, education, and positive attitude for virtual communication and virtual leadership within multinational companies in Brazil. Brazil as a country, as well as companies in Brazil, needs to provide opportunities and possibilities for excellent virtual communication and leadership. For instance, facetual communication and attication are important concepts on the way for companies of becoming virtualized.

Esta dissertação busca compreender a imersão em realidade virtual (VR) enquanto problema de produção material, semiótica e cultural de espacialidades. Remete-se a imersão em VR à espacialidade panorâmica, caracterizada pela extensão homogênea e totalizante do plano visível em torno de um ponto de vista. Avalia-se, assim, a imersão sensorial como acontecimento irredutível a seu eventual assentamento tecnológico, o que encaminha mapeamentos de estratégias transmidiáticas (pintura, cinema, arquitetura etc.) para o fechamento espacial. Indagam-se os regimes de saber-poder aos quais se agenciam essas estratégias, concluindo-se que a imersão panorâmica responde a uma espisteme antropocêntrica e racionalista, com a subordinação da matéria a um espaço-receptáculo, por sua vez subordinado a um sujeito único e central. Tal sistematização do espaço, no que produz o quadro enquanto recorte parcial de um conjunto mais amplo, evidencia o invisível como virtualidade do campo visível, ao que a forma-panorama responde com uma colonização do extracampo. Assim, a função imediata do extracampo de sugerir conjuntos ausentes, em meios como a pintura e o cinema, se extravia nas operações de desenquadramento e reenquadramento em VR. Para estudar como a realidade virtual atualiza espacialidades imersivas e aberturas para conjuntos exteriores, foram realizadas observações com um Google Cardboard, tomando como corpus de análise três vídeos do aplicativo Within, disponível em Android e iOS. Entre os resultados, concluiu-se que a realidade virtual se agencia não apenas à cabeça e ao pescoço do usuário, mas ao seu corpo inteiro, e que a imersão ocorre mediante a invisibilização dos conjuntos que emolduram o espaço eletrônico. Identificaram-se atualizações de uma série de estratégias expressivas para a captura da “liberdade” de enquadramento, como a utilização de ruídos sonoros, linhas de visão e movimento, afectos de rostidade e montagem espacial privilegiando apenas uma zona do plano visível. Os mesmos recursos que “abriam” centrifugamente as telas pictórica e cinematográfica servem, em VR, para instaurar um jogo internalizante de linhas centrípetas. Com isso, se relacionou a imersão panorâmica em VR não mais ao mecanismo panóptico e enclausurante típico das sociedades disciplinares, mas a um modelo de fractalismo “aberto” que caracteriza o funcionamento do poder nas sociedades de controle.
This work seeks to comprehend immersion in virtual reality (VR) as a problem of material, semiotic and cultural production of spatialities. Immersion in VR is linked to a panoramic spatiality, characterized by the homogeneous and totalizing extension of the visible field around a point of view. Sensorial immersion is therefore reckoned as an event which is irreducible to its technological grounding, leading to the mapping of transmediatic strategies (in painting, cinema, architecture etc.) for the enclosure of space. The text inquires the regimes of truth and power to which these strategies are assembled and concludes that panoramic immersion serves an anthropocentric and rationalist episteme, subordinating matter to a vessel-space and a vessel-space to a single centralized subject. Such a systematization of space, while producing the frame as a partial selection of a wider set, also creates the invisible as virtuality of the visible field, to which the panorama will provide an answer by colonizing the out-of-field. The out-of-field’s immediate function of pointing to absent sets in mediums such as painting and cinema perishes, therefore, with VR’s operations of deframing and reframing To study how virtual reality actualizes immersive spatialities and openings to external sets, observations were conducted with the use of a Google Cardboard, having as object of analisys three videos from the app Within, available for Android and iOS. Among the results, it was found that virtual reality connects not only the user’s head and neck to the digital space, but his whole body, and that immersion occurs by invisibilizing the external sets which enframe the digital space. A series of expressive strategies were found to be actualized to capture the “freedom” of framing, such as sound noises, lines of vision and movement, face affects and spatial montage favoring a single limited portion of the visible field. The same expedients which centrifugally “opened” pictorial and film screens now act, in VR, to establish an internalizing game of centripetal lines. Panoramic immersion in VR was finally related not anymore to the panoptic and besieging mechanism typical of the disciplinary societies, but to a model of “open” fractalism which caracterizes the operation of power in the societies of control.

The Field Day Anthology of Irish Writing (1991) is a three-volume, 4044 page collection of Irish literary, political, religious, philosophical and cultural texts, spanning the period of 550 AD to 1990. Its publisher, the Field Day Theatre and Publishing Company, stresses the need for an interventionist theatre and critical discourse, which has the aim of representing and interrogating the current condition of Ireland, particularly that of the North of Ireland. Basing its analyses of the Irish/British situation on a belief that it is a colonial problem, Field Day, throughout the 1980s and into the early 1990s, produced plays and published pamphlets in which various aspects of Ireland's colonial experience were interrogated. The idea of an anthology was raised formally in 1984 as a way of constructing a narrative out of the cultural production of the various groups and sects that have inhabited the island. Such a collection would be a syncretic statement of Irish written culture and could contribute towards debates on the questions of identity and cultural/religious/national affiliation facing the people(s) of Ireland. The Field Day Anthology's publication in November 1991 was greeted by the type of criticism rarely encountered by any text. The loudest voices of opposition came from critics angry at both the text's sins of omissions and its perceived ideological baggage and agenda. The text was characterized as a nationalist narrative, as antagonistic towards or ignorant of the particular circumstances and traditions of the North, and as a monocular colonially-obsessed production. Foremost among the criticisms was the perception that the text did not adequately represent women's writing. Following the storm of protest, Field Day announced that a volume devoted to women's writing would be produced. At the time of writing, this volume has yet to appear. While I am sympathetic of many of the criticisms, I also believe that the production was attacked for reasons other than its own particular merits or demerits. I argue in Chapter 4 that it is essential to retain a view of the anthology as a multiple and complex production, rather than as a wholly coordinated programme. While I am interested in the institutional background of the anthology, and in the controversies it provoked (I devote Chapter 2 to these issues), my chief concern is to analyze the anthology as a text that engenders questions on, for example, on the nature of the canon (Chapter 3), on questions of post-colonial agency (Chapter 6), and on writing's relationship to Irish history and historical revisionism (Chapter 5).

The student-teaching experience is the most noteworthy experience for a teacher candidate (TC) in a teacher preparation program. University supervisors play a crucial role in this experience through feedback, support and maintaining congruency between the student teaching environment and the teacher preparation program. Due to issues related to time, distance and budget, completing on-site observations of the TC can be challenging. This article serves as a practical guide for university supervisors to virtually observe TCs using synchronous video conferencing. Technology and equipment needed, preparation tasks, and factors to consider are explored.

Nya teknologier utvecklas hela tiden och ett fåtal av dessa har möjligheten att revolutionera tillvägagångssättet av hur vi gör saker. Utbildningsområdet är ett av de äldsta områdena som finns kvar även idag och som återkommande har dragit nytta av ny teknologi för att förbättra kärnkonceptet.Vår forskning täcker fenomenet virtual reality som ett supplement i utbildningen. Vi undersöker hur studenter vid Högskolan i Borås uppfattar introduceringen av denna moderna teknologi som ett hjälpmedel till deras studier. Vi använder oss utav enkäter för att samla in information, och vi fick svar från 143 studenter. Vår slutats anser att den övergripande attityden är positiv hos studenterna, samtidigt som vi behåller en viss skepticism för att detta resultat ska ligga till grund som fakta för framtida beslutstaganden.
There is a constant development of new technologies happening in the world. A handful of these are deemed to have the potential of truly revolutionizing the way we do things. The field of education is one of the oldest fields that continue to be present even today and has time and time again come to make use of new technologies that streamlines and improves upon its core concept.The research we put forward covers the case of virtual reality as an improvement into the field of education. We research how students at the University of Borås perceive the introduction of this novel technology as an aid in their studies. We utilize questionnaires in order to receive this information and received a total of 143 respondents’ answers. We conclude that the general attitude of the students is positive, while maintaining skepticism in terms of this result as a piece of document for proving the results as facts.

A Synthetic Learning Environment (SLE) the Virtual Field Trip (VFT) was designed to increase vocabulary acquisition and knowledge by utilizing simulation based technologies and leveraging sound educational findings. Vocabulary acquisition is considered a prerequisite to becoming a good reader and therefore a critical predictor of academic and lifelong success for early learners, however, teachers report that students lack the real world knowledge required for vocabulary knowledge. The VFT provides a meaningful context for anchored and situated instruction. Second grade students were assigned to either use the VFT or to listen to stories read aloud by a researcher on a video tape. While results did not indicate significant vocabulary acquisition on a series of 3 vocabulary tests; students who used the VFT did use significantly more words in a post exposure writing sample than students in the story group indicating an increase of words known at a level of depth sufficient to warrant their use in a writing sample. Students who used the VFT also reported increased motivation to use SLEs like the VFT for future learning objectives and that VFTs were fun. Findings related to the self-efficacy of students as measures immediately following each vocabulary test did not reveal a significant increase for VFT users. Students using the VFTs did not report learning more words than those students assigned to the story group. Limitations of the current study and directions for future research are discussed.
Ph.D.
Other
Sciences
Modeling and Simulation

This study evaluated a new Integrated Science Learning Environment (ISLE) that bridged the gaps between the traditionally separate classroom, field trip, and information technology milieus. The ISLE model involves a multi-faceted design to address the three basic forms of learning: acquisition of knowledge, change in emotions or feelings, and gain in physical or motor actions or performance. A holistic approach to teaching at the university level encompassed a step-wise, cumulative strategy that reinforced all scales of the Constructivist Learning Environment Survey (Personal Relevance, Uncertainty of Science, Shared Control, Critical Voice, and Student Negotiation) and minimised the potentially detrimental effects of information overload and non-linear processing. By addressing individuals and recognising limitations, the same conceptual and logistical frameworks were applied to teachers and to students uniformly in the classroom and in the field. This key factor of the ISLE program broadened all participants’ horizons and enabled them to see their role within the ‘big picture’. Thus, the common elements (knowledge) and basic components (understanding) in each realm became evident and the power of transfer for both content and concept was realised. A process approach to information technology provided a logical and meaningful mechanism for continuously scaling the program perspective from the classroom setting to the unique global environment of the World Wide Web. The final product of the ISLE program (virtual field trip) was constructed by linking the elements common to the supporting learning environments (university classroom, field trip, and information technology) at their basic levels: newness, massiveness, and appropriateness.A combination of qualitative methods and quantitative measures provided insight into the field trip milieu and evaluation of the near- and far-term effects of exposure to constructivist pedagogy answering the general question of whether changing teachers’ learning environments might affect a change in their respective students’ learning environments. Quantitative assessment through learning environment dimensions, attitude scales, and concept map analyses was supported by qualitative data derived from reflective field journals, interviews, and observations to investigate the impact of the emergent model. Data were collected from classroom teachers and their students to assess the impact of the ISLE program in terms of promoting a constructivist classroom learning environment, teachers’ attitudes toward information technology, and teachers’ conceptual development. School teacher and student subgroups were compared in terms of the teachers’ university/field trip program experience and content background. To this end, three new versions of the Constructivist Learning Environment Survey (CLES) were shown to be valid and useful in secondary schools and graduate university courses in Texas. Data from 1079 students in 59 classes in north Texas were subjected to principal components factor analysis confirmed the factor structure, internal consistency reliability, discriminant validity, and the ability to distinguish between different classes and groups for the comparative student form (CLES-CS). Descriptive statistics supported the usefulness of the comparative teacher (CLES-CT) and adult (CLES-A) forms. Administration of these versions of the same instrument was used to characterise the learning environment of the ISLE university/field trip program, as well as the public/private school classrooms.Further analysis and interpretation of these data suggest that the ISLE program was effective in terms of the degree of implementation of constructivist teaching approaches in the teachers’ school classrooms as assessed by teachers’ perceptions of the learning environment of their current classroom environment relative to other classes taught by them previously and students’ perceptions of the learning environment of their classroom environment relative to classes taught by other teachers in their school classrooms. Additional data suggest that the ISLE program was effective in terms of teachers’ perceptions of the university/field trip learning environment; changes in teachers’ attitudes to information technology; and teachers’ conceptual development. When an ANOVA was used to compare students’ perceptions of THIS and OTHER classes, statistically significant differences were found for some CLES scales. In particular, students whose teachers had attended the ISLE program (THIS) perceived higher levels of Personal Relevance and Uncertainty of Science in their classrooms relative to the classrooms of other teachers in the same schools (OTHER). From a practical point of view, this study documents a new model for improving learning and understanding in the field of education, specifically science education. Participation in the ISLE program provided a tangible opportunity for teachers to gain organised knowledge to make practical changes in their school classrooms. From a research point of view, this study makes a unique contribution to the field of learning environments by evaluating a comprehensive professional development program that used information technology to initiate teacher change from the central perspective of the learning environment.Development and validation of the CLES-CS contributes to a useful range of instruments for a variety of classroom contexts within the burgeoning field of learning environments research. The real world is where theory and practice come together and science becomes relevant, making sense that leads to understanding. The conceptual and logistical frameworks of the ISLE model seamlessly merged theory and practice with science and education through effective applications of information technology to create a rich learning environment. Virtual field trips, based on the ISLE model, can enable the principles of student-centred inquiry and constructivism to be practised for the benefit of all styles and ages of lifelong learners.

Thesis (M.S. in Computer Science) Naval Postgraduate School, September 1998.
Thesis advisor(s): Rudolph P. Darken. "September 1998." Includes bibliographical references (p. 97-99). Also Available online.