Studien undersöker hur virtual reality-filmer från Thomas Cooks app ”Holiday 360” kan påverka konsumentens inställning till varumärket. Uppsatsen redovisar intervjupersonernas upplevelser av två VR-filmer i förhållande till en av Thomas Cooks 2D-filmer och tar upp aspekter som associationer till varumärket före, emellan och efter filmvisningarna, deras uppleva närvaro i den virtuella omgivningen samt reflektioner kring om och i så fall hur appen kan fylla en funktion för respondenten. Undersökning utgörs av individuella intervjuer med åtta respondenter som samtliga tagit del av två VR-filmer och en 2D-film. Bakgrundsinformation om projektet ”Holiday 360” har samlats in via ett YouTube-föredrag med representant från Thomas Cook. Studien visar bland annat tre fall där VR-filmerna i undersökningen påverkat respondentens inställning till varumärket positivt. Varumärket uppfyller också ett funktionellt behov hos respondenterna och flertalet intervjupersoner upplever också en högre känsla av närvaro i VR-filmerna i än i 2D-filmen. Dessa tre aspekter indikerar på att starkare attityder och positiv inställning till Thomas Cook, bland vissa av respondenterna, kan skapas med hjälp av VR-film. Tecken finns dock också på att VR som teknik inte utnyttjats till sin fulla potential. / This study examines Thomas Cook’s virtual reality videos through the app "Holiday 360" can affect the consumers attitude towards the brand. The essay provides a presentation of the participants experiences of VR including their associations of the brand before, during and after the VR- and 2D-experiences, their sense of presence in a virtual world and reflections regarding whether and in what case this app could satisfy a functional need. The study consists of eight individual interviews regarding two VR-videos and one 2D-video. Background information about “Holiday 360” was presented in a lecture by a Thomas Cook representative, found at YouTube. The results show that VR affects some of the respondents in a positive way and that VR-videos also fulfill a functional need when planning a journey. At last, VR advertising is capable of enhancing a sense of presence. These three aspects indicate that VR can affect brand attitude and brand loyalty. However, there are signs that could indicate that VR as technology are not being exploited to its full potential.

Wire-arc additive manufacturing (WAAM) is becoming increasingly common for large scale additive manufacturing (AM) applications because of its high deposition rate (2-3 kg/hr.). The rapid temperature changes and subsequent evolution of mechanical properties during AM can lead to large distortion and residual stresses. Finite element modeling of the AM process shows promise to minimize part distortion and residual stresses through improved path planning and process parameter optimization. However, accurate material properties of M250 before and after heat treatment are needed to properly characterize the property evolution from annealed to AM, to aged. Due to limited data on annealed M250, this research presents the mechanical response of solution annealed M250 maraging steel. Testing at temperatures up to 900 degrees Celsius and strain rates from quasi-static to 1 s-1 was performed to provide more representative mechanical properties for AM parts and provide a correlation between AM, aged, and annealed M250 maraging steel.

La présente maîtrise est réalisée à la demande de Recherche et Développement pour la Défense Canada (RDDC) à Valcartier. Dans un contexte militaire, la capacité à caractériser indépendamment un matériau pour la simulation numérique est primordiale for trois raisons. Premièrement, les matériaux utilisés ne sont pas répandus comme ceux utilisés en aéronautique ou bien en construction automobile. Deuxièmement, les paramètres des matériaux spécifiques au domaine militaire sont rarement divulgués. Troisièmement, l’utilisation d’alliages secrètement développés prohibe la caractérisation par une seconde entité. Le présent projet à pour objectif the permettre au RDDC Valcartier d’effectuer de faon indépendante la détermination des paramètres du modèle Johnson-Cook [1] [2] de matériaux ductiles. Pour arriver à ce point, le modèle Johnson-Cook est présenté à partir de la théorie de la mécanique de l’endommagement des milieux continus (CDM). La méthode de caractérisation proposée par Johnson et Cook dans les références [1] et [2] est introduite. Après quoi, les techniques et moyens expérimentaux nécessaires sont également décrits. Le reste du mémoire se concentre sur les paramètres statiques du modèle (A, B, n, D1, D2, et D3), puisqu’ils sont prédominants dans la modélisation de la mécanique de l’endommagement comparativement aux autres paramètres [2], [16], et [27]. Quelques lacunes sont observées dans la méthode proposée par les auteurs du modèle. Finalement, une amélioration est proposée pour la partie statique de la méthode de caractérisation. La technique utilisée pour cette proposition utilise le système photogrammétrique ARAMIS afin de mesurer les déformations locales des échantillons sur tout la plage de temps et de faciliter la corrélation avec les simulations numériques effectuées avec le code explicit Ls-Dyna. / This Master of Science thesis is realized for the Defence Research and Development for Canada (DRDC) Valcartier. In a military context, the capacity to characterise independently the material for numerical simulation is important for three reasons. First, the material used are not widely used as aeronautical and car industries material. Secondly, the material parameters militarily relevant are rarely published. Thirdly, the used of secretly developed alloys could prevent from its characterisation by an external entity. The aim of the present study is to allow the DRDC Valcartier to self-characterize ductile metals for their simulation with the model Johnson-Cook, proposed in [1] and [2]. To get to this point, the Johnson-Cook model is presented starting from the CDM theory. The characterization method proposed by Johnson and Cook in [1] and [2] is introduced. Then, the experimental tests and equipments are described. After what, the work is focused on the static parameters (A, B, n, D1, D2, and D3), since those parameters are predominant compared with others in damage mechanics [2], [16], and [27]. Few lacks are pointed out of the suggested method. Finally, an improvement of the static part of the characterization method is proposed and tested. This added part includes the used of the photogrammetry system ARAMIS to monitor the experimental tests and simulation of those tests with LS-Dyna.

Cette thèse présente quelques avancées sur la représentation efficace de l’apparence matérielle dans une simulation de l’éclairage. Nous présentons deux contributions : un algorithme pratique de simulation interactive pour rendre la réflectance mesurée avec une géométrie dynamique en utilisant une analyse fréquentielle du transport de l’énergie lumineuse et le shading hiérarchique et sur-échantillonnage dans un contexte deferred shading, et une nouvelle fonction de distribution pour le modèle de BRDF de Cook-Torrance. Dans la première partie, nous présentons une analyse fréquentielle de transport de l’éclairage en temps réel. La bande passante et la variance sont fonction de l’éclairage incident, de la distance parcourue par la lumière, de la BRDF et de la texture, et de la configuration de la géométrie (la courbure). Nous utilisons ces informations pour sous-échantillonner l’image en utilisant un nombre adaptatif d’échantillons. Nous calculons l’éclairage de façon hiérarchique, en un seul passage. Notre algorithme est implémenté dans un cadre de deferred shading, et fonctionne avec des fonctions de réflectance quelconques, y compris mesurées. Nous proposons deux extensions : pré-convolution de l’éclairage incident pour plus d’efficacité, et anti-aliasing utilisant l’information de fréquence. Dans la deuxième partie, nous nous intéressons aux fonction de réflectance a base de micro-facette, comme le modèle de Cook-Torrance. En nous basant sur les réflectances mesurées, nous proposons une nouvelle distribution des micro-facettes. Cette distribution, Shifted Gamma Distribution, s’adapte aux donnée avec plus de précision. Nous montrons également comment calculer la fonction d’ombrage et de masquage pour cette distribution. Dans un deuxième temps, nous observons que pour certains matériaux, le coefficient de Fresnel ne suit pas l’approximation de Schlick. Nous proposons une généralisation de cette approximation qui correspond mieux aux données mesurées. Nous proposons par ailleurs une nouvelle technique d’optimisation, canal par canal, en deux étapes. Notre modèle est plus précis que les modèles existants, du diffus au spéculaire. / This thesis presents some advances in efficient representation of material appearance in a lighting simulation. The scope of this thesis is two-fold: an interactive shading algorithm to render measured reflectance with dynamic geometry using frequency analysis of light transport and hierarchical shading and up-sampling in deferred shading context, and a new normal distribution function for the Cook-Torrance micro-facet BRDF model, along with a new shadowing and masking function and a generalization of Schlick’s approximation of the Fresnel term. In the first part, we introduce a real-time frequency analysis of light transport framework that allows us to estimate the bandwidth and variance of the shading integrand. The bandwidth and variance are a function of frequencies in the illumination, distance traveled by light, BRDF and texture, and the geometry configuration (curvature). We use this information to under-sample the image, and also use an adaptive number of samples for shading. We devise a single-pass hierarchical shading and up-sampling scheme to assemble an image out of the sparsely shaded image pixels. We extend our interactive technique to use pre-convolved shading for real-time performance. We also take advantage of the bandwidth information to perform multi-sample anti-aliasing in deferred shading by subsampling only a small portion of image pixels whose bandwidth is smaller than 1 pixel^-1. In the second part, we propose a new distribution function for the Cook-Torrance micro-facet BRDF, based on our observations on the reflectance measurements. We isolate the distribution components of the reflectance data and directly observe that existing distribution functions are insufficient. Then we devise the Shifted Gamma Distribution (SGD) fitting more accurately to the data. We derive the shadowing and masking function from the distribution. We observe that not all materials have the Fresnel behavior expected by Schlick’s approximation. Hence, we generalize the Schlick’s approximation to more accurately fit the model to the measurements. We introduce a two-step fitting approach, that fits each RGB channel separately — accounting for wave-length dependent effects. We show that our shading model outperforms existing models and accurately represents a wider range of materials from diffuse to glossy and highly specular materials.

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.

O objetivo principal deste trabalho é discutir estimação e diagnóstico em modelos semiparamétricos com resposta binomial negativa, mais especificamente, modelos de regressão com resposta binomial negativa em que uma das variáveis explicativas contínuas é modelada de forma não paramétrica. Iniciamos o trabalho com um exemplo ilustrativo e fazemos uma breve revisão dos modelos paramétricos com resposta binomial negativa. Em seguida, introduzimos os modelos semiparamétricos com resposta binomial negativa e discutimos alguns aspectos de estimação, inferência e seleção de modelos. Dedicamos um capítulo a procedimentos de diagnóstico, tais como desenvolvimento de medidas de alavanca e de influência sob os aspectos de deleção de pontos e influência local, além de abordar a análise de resíduos. Reanalizamos o exemplo ilustrativo sob o enfoque semiparamétrico e apresentamos algumas conclusões. / The aim of this work is to discuss some aspects on estimation and diagnostics in negative binomial regression models which an explanatory continuous variable is modeled nonparametrically. First, an illustrative example is presented and analyzed under parametric negative binomial regression models. The proposed models are then introduced and some aspects on estimations, inference and model selection are presented. Particular emphasis is given on the development of diagnostic procedures, such as leverage measures, Cook distances, local influence approach and residuals. The motivated example is reanalyzed under the semiparametric viewpoint and some conclusions are given.

Este trabalho tem como proposta apresentar a metodologia de diagnóstico de influência local de Cook (1986) conjuntamente com a metodologia de seleção da perturbação adequada proposta por Zhu et al. (2007) no modelo de calibração ultraestrutural com réplicas. A metodologia de Cook (1986) ser´a utilizada para investigar a robustez e a sensibilidade do modelo, onde os esquemas de perturbação adotados foram ponderação de casos e na variável resposta. Perturbar o modelo e/ou os dados de forma arbitrária pode conduzir a interpretações sobre a análise de diagnóstico e a conclusões equivocadas. Portanto, este trabalho irá avaliar as perturbações propostas segundo a metodologia de Zhu et al. (2007) e caso as perturbações não sejam adequadas, iremos propor uma nova forma de fazer as perturbações. Foi utilizado como aplicação a análise de um conjunto de dados com réplicas balanceadas e foram avaliadas quais patamares e laboratórios exercem um efeito desproporcional nas inferências feitas sob o modelo. / This paper aims to present the local influence diagnostic methodology of Cook (1986) along with the selection of the appropriate perturbation schemes proposed by Zhu et al. (2007) in ultrastructural calibration model with replicas. The methodology of Cook (1986) will be used to investigate the robustness and sensitivity of model, where the adopted perturbation schemes were weighting cases and response variables. Perturbing the model and/or data in an arbitrary way can lead to miss interpretations of diagnostic analysis and wrong conclusions. Therefore, this study will evaluate the induced perturbations according to the methodology of Zhu et al. (2007) and if the perturbations are not suitable, we will propose a new way of perturbing the model or the data. As an application it was considered a data set with balanced repeated replication to evaluate which levels and laboratories exercise a disproportional effect on inferences made in the model.

O objetivo principal deste trabalho é discutir estimação e diagnóstico em modelos semiparamétricos com resposta binomial negativa, mais especificamente, modelos de regressão com resposta binomial negativa em que uma das variáveis explicativas contínuas é modelada de forma não paramétrica. Iniciamos o trabalho com um exemplo ilustrativo e fazemos uma breve revisão dos modelos paramétricos com resposta binomial negativa. Em seguida, introduzimos os modelos semiparamétricos com resposta binomial negativa e discutimos alguns aspectos de estimação, inferência e seleção de modelos. Dedicamos um capítulo a procedimentos de diagnóstico, tais como desenvolvimento de medidas de alavanca e de influência sob os aspectos de deleção de pontos e influência local, além de abordar a análise de resíduos. Reanalizamos o exemplo ilustrativo sob o enfoque semiparamétrico e apresentamos algumas conclusões. / The aim of this work is to discuss some aspects on estimation and diagnostics in negative binomial regression models which an explanatory continuous variable is modeled nonparametrically. First, an illustrative example is presented and analyzed under parametric negative binomial regression models. The proposed models are then introduced and some aspects on estimations, inference and model selection are presented. Particular emphasis is given on the development of diagnostic procedures, such as leverage measures, Cook distances, local influence approach and residuals. The motivated example is reanalyzed under the semiparametric viewpoint and some conclusions are given.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-19T17:20:50Z No. of bitstreams: 1 JOSÉ IRAPONIL COSTA LIMA - DISSERTAÇÃO PPGMAT 2008..pdf: 699592 bytes, checksum: 5198d2760970321e3eefbeceb3ae9266 (MD5) / Made available in DSpace on 2018-07-19T17:20:50Z (GMT). No. of bitstreams: 1 JOSÉ IRAPONIL COSTA LIMA - DISSERTAÇÃO PPGMAT 2008..pdf: 699592 bytes, checksum: 5198d2760970321e3eefbeceb3ae9266 (MD5) Previous issue date: 2008-09 / O método de influência local proposto por Cook (1986) é uma importante ferramenta na análise da influência conjunta das observações nos resultados de um ajuste de regressão. Esta técnica tem como objetivo principal avaliar mudanças nos resultados da análise quando pequenas perturbações são incorporadas ao modelo e/ou aos dados. Se essas perturbações causarem efeitos desproporcionais nas estimativas, pode ser indí io de que o modelo está mal ajustado ou que possam existir afastamentos sérios das suposições feitas para o mesmo. Apesar do método baseado na curvatura normal proposto por Cook (1986) ser de grande utilidade, este possui alguns in convenientes. Por exemplo, a curvatura normal pode tomar qualquer valor real e não é invariante sob uma mudança uniforme de escala. Neste trabalho, estudamos a influência local conforme, proposto por Poon & Poon (1999) em modelos de regressão, que tem como objetivo contornar estes inconvenientes. Mais especificamente, aplicamos esta técnica de diagnóstico para os modelos de regressão log-Birnbaum-Saunders e derivamos as matrizes apropriadas para obter a influência local nos parâmetros estimados de um modelo mais geral, o modelo de regressão senh-normal. Finalmente, ilustramos a teoria desenvolvida em conjuntos de dados reais. / The method of local influence proposed by Cook (1986) is an important tool in the analysis of the joint influence of the observations in the results of a regression fit. This technique has as main goal to evaluate hanges in the results of the analysis when small perturbations are incorporated the model and/or to the data. If these perturbations would cause non proportion effect it can be indication of that the model is badly fitted or that possible departures from the assunptions made for this model an exist. Although the method based on normal curvature proposed by Cook (1986) has been demonstrated to be very useful, this possesses some issues. For example, the normal curvature may take any value and it is not invariant under a uniform hange of scale. In this work, we study the conformal local influence, proposed by Poon & Poon (1999) in regression models, that has as objective to address these issues. More specifically , we apply this technique of diagnostic for log-Birnbaum-Saunders regression models and we derive matrices appropriate to obtain the conformal local influence in the estimated parameters of a more general model, the senh-normal regression model. Finally, we consider empiritical examples with real data to illustrate the theory developed.

Orientador: Nilo Sérgio Sabbião Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T11:11:16Z (GMT). No. of bitstreams: 1 Moraes_Fabianede_M.pdf: 11400492 bytes, checksum: ccae3b13c04ead483ac2377969757130 (MD5) Previous issue date: 2013 / Resumo: A carne assada, um item bem aceito pelos clientes de restaurantes coletivos, é comumente preparado com lagarto bovino (músculo Semitendinosus). O mercado da alimentação fora de casa está em franca expansão. Para atender à maior demanda dos restaurantes de coletividade, é necessário o aumento da produção e a busca e aprimoramento de tecnologias. O preparo de alimentos pelo sistema cook chill preserva as características sensoriais, reduz as perdas de processo, e resulta em alimento mais padronizado e microbiologicamente mais estável, quando comparado com sistemas convencionais, permitindo melhor programação e centralização da produção. Visando à comparação destes dois sistemas para a produção de lagarto bovino, na Etapa I desse estudo foi executado um planejamento experimental para a maximização do rendimento e da força de cisalhamento no produto processado pelo sistema cook chill. Foi aplicado um delineamento composto central rotacional para as variáveis independentes: tempo de cozimento, escala de injeção de vapor e temperatura do forno. Para a definição dos níveis das variáveis independentes foram realizados estudos preliminares. Foram obtidos maiores rendimentos no cozimento com menores tempos de cocção, maiores escalas de injeção de vapor e temperaturas intermediárias. A carne cozida a 177,7 °C apresentou menor força de cisalhamento, que é maior com o aumento do tempo de cozimento. Para a Etapa II, foram selecionados dois tratamentos dentre os dezessete do sistema cook chill da Etapa I: um de mínima força de cisalhamento (cook chill 1) e outro de máximo rendimento no cozimento (cook chill 2), os quais foram comparados com o sistema convencional por análises físico químicas, microbiológicas e sensoriais, no processamento e durante a estocagem. Os dois sistemas propiciaram carne assada de boa qualidade, em relação aos parâmetros analisados. As carnes processadas pelo sistema cook chill obtiveram melhor avaliação para os atributos sensoriais: aparência e gosto salgado. Embora a carne processada pelo sistema convencional tenha sido mais bem avaliada no atributo textura no corte com a faca e sua força de cisalhamento tenha sido a maior, não houve diferença significativa para o atributo textura na mastigação. A maior oxidação lipídica encontrada no lagarto processado pelo sistema cook chill 2 não impactou nos resultados da análise sensorial. Obteve-se carne com boa qualidade microbiológica até o quinto dia de estocagem nos três processamentos, destacando-se a carne processada pelo sistema cook chill 1 pelas baixas contagens microbianas mesmo no décimo dia de estocagem. Assim, o processamento de carne assada pelo sistema cook chill é vantajoso, principalmente, por permitir a produção de alimento com características mais estáveis, propiciar melhor programação e favorecer o aumento e a centralização da produção em restaurantes de coletividade / Abstract: Roast beef is a well accepted item by food service customers and it is commonly prepared with Semitendinosus beef. The food service market is currently booming. To meet the higher demands, it is necessary to increase production, develop new technologies as well as improve existing ones. Food preparation by the cook chill system preserves sensory characteristics, reduces water loss and delivers more standardized and microbiologically stable food, when compared to conventional systems, allowing better planning and centralization of production. In order to compare these two systems in terms of production of Semitendinosus muscle, Phase I of this study involved an experimental design to maximize cooking yield and shear force on the product processed by cook chill system. It was applied a central composite design for the independent variables: cooking time, steam scale injection and oven temperature. To define the levels of these independent variables preliminary studies were performed. Cooking yield is maximized when time is reduced, and higher scales of steam injection and intermediate temperatures are applied. The meat cooked at 177.7 ° C had lower shear force which increases when cooking time increases. For Phase II, two treatments were selected from the seventeen treatments in Phase I: one of minimal shear force (cook chill 1) and another of maximum cooking yield (cook chill 2), which were compared with the conventional system using physical chemical, microbiological and sensorial analysis during processing and storage. The two processing systems, cook chill and conventional, resulted in roast beef of good quality, in relation to the analyzed parameters. Meats processed using the cook chill system had better sensory evaluation in terms of the following attributes: appearance and salty taste. Although meat processed by the conventional system were more thoroughly evaluated in terms of cutting texture and had the biggest shear force, there was no significant difference in the mouth texture attribute between the samples. The higher lipid oxidation found on the meat processed by cook chill 2 system did not impact the sensorial analysis results. Meat with good microbiological quality were obtained up to the fifth day of storage for the three cases, especially for meat processed by cook chill 1 system, that showed low results until the tenth day of storage. Roast beef processing by cook chill system is advantageous, especially because of its ability to produce food that is higher in terms of stability, provide better programming and promote the increase and centralization of production in food service / Mestrado / Consumo e Qualidade de Alimentos / Mestra em Alimentos e Nutrição