Designers use various representations to externalize their ideas, physical models being an important one. Physical models are widely used by designers and their use is promoted as an effective design tool by industry and government agencies. However, very little is known about the cognitive effects of physical models in the design process; the available guidelines are conflicting. Some researchers argue for the frequent implementation of physical models, while others observe that the use of physical models fixates designers. In light of these conflicts, the research discussed in this dissertation focuses on understanding the cognitive effects of physical models and developing guidelines for aiding designers in their implementation. A combination of controlled lab studies and qualitative studies is adopted to achieve said goal. The results from the controlled studies show that physical models supplement designers’ erroneous mental models and help them to come up with more ideas satisfying the problem requirements. These studies also demonstrate that design fixation is not inherent in physical modeling, but it is caused by the Sunk Cost Effect. According to Sunk Cost Effect, as designers spend more time building physical models of their initial ideas, they tend to fixate more to the variations of those ideas. A qualitative study on industry-sponsored projects and development cases of award-winning products further supports these results in more realistic situations. Further, the studies reported in this dissertation show that physical models can be effective tools for the mitigation of fixation to undesirable design features in a flawed example; however, these results can also depend upon the experience level of a designer in solving open-ended design problems. With these insights from the series of studies, a set of guidelines and a Model Error Reeducation Method (MERM) are formulated and tested with novice designers. MERM helps designers in identifying critical loads and interface designs they miss in their original designs, before prototyping. The results from the testing of this method show that this method is very useful in avoiding said errors in physical modeling.

Doctor of Philosophy / Department of Physics / Dean A. Zollman / A series of teaching activities using physical models was developed to present some portions of physics of Positron Emission Tomography (PET) and investigate students’ understanding and transfer of learning in physics to a medical technology. A teaching interview protocol consistent with a qualitative research methodology was developed and administered to the students enrolled in an algebra-based introductory level physics course. 16 students participated in individual interviews and another 21 students participated in the group sessions. The major objectives of the teaching interviews were to investigate students’ transfer of physics learning from their prior experiences to the provided physical models, from one model to the other and from the models to the PET problems. The study adapted phenomenological research methodology in analyzing students’ use of cognitive resources and cognitive strategies during knowledge construction and reconstruction. A resource based transfer model framed under the cognitive theory of learning and consistent with contemporary views of transfer was used to describe the transfer of physics learning. Results of the study indicated both appropriate and inappropriate use of the students’ prior conceptual resources in novel contexts. Scaffolding and questioning were found to be effective in activating appropriate and suppressing the inappropriate resources. The physical models used as analogies were found useful in transferring physics learning to understand image construction in PET. Positive transfer was possible when the models were introduced in an appropriate sequence. The results of the study indicate the occurrence of three types of non-scaffolded transfer – spontaneous, semi spontaneous and non-spontaneous. The research found connections between sequencing of hints and phrasing of information in activating students’ different conceptual resources. A qualitative investigation based on Vygotsky’s Zone of Proximal Development (ZPD) has been completed in two contexts – one involving an instructor and the other involving peers. Significant expansion of the students’ ZPD occurred through peer interaction. The results indicate that the appropriate sequencing of learning activities and group interactions can promote learning. Additional research in transfer of physics learning from macroscopic phenomena to microscopic phenomena are warranted by the conclusions of this work.

O presente trabalho se propõe a analisar o método para avaliação da iluminação natural, utilizando os modelos físicos reduzidos como ferramenta, com o intuito de avaliar os aspectos quantitativos e qualitativos da luz. Foi realizado um diagnóstico deste método mostrando suas qualidades e limitações. O uso de modelos físicos reduzidos é um dos métodos mais antigos de avaliação da iluminação natural. Este é um instrumento preciso, caso o modelo seja executado de forma correta, considerando-se que a propagação da luz segue os mesmos princípios tanto em um modelo físico reduzido, como em um edifício em escala real. Através deste instrumento, torna-se possível testar as diversas soluções em busca da eficiência energética e do conforto visual. Para verificar o grau de confiabilidade dos resultados através da aplicação deste método foi feita uma comparação entre medições da iluminância em um modelo físico reduzido e medições realizadas em um ambiente real correspondente. Com o objetivo de demonstrar os procedimentos necessários para o uso de modelos físicos reduzidos no estudo da iluminação natural, foram feitas medições em dois modelos com estratégias de iluminação diferenciadas. Um deles possui iluminação natural unilateral, ao passo que, o segundo possui as características da abertura unilateral semelhante ao primeiro, porém, com a inclusão de uma prateleira de luz. Já o ambiente real foi selecionado devido à simplicidade de sua geometria e a facilidade de acesso para a realização das medições. As conclusões demonstram que para alcançar resultados confiáveis é necessário construir os modelos com precisão, sendo recomendável medir a iluminância dos mesmos sob diversas condições de céu, para que desta forma seja possível avaliar o desempenho médio da iluminação natural por um longo período. / The present work considers the analysis of scale models for daylighting evaluation, aiming at investigating quantitative and qualitative aspects of light. A diagnosis of scale modeling was carried out, showing its strengths and limitations. Scale modelling is one of the oldest methods for daylighting evaluation. It is also a precise instrument, when properly constructed, considering that light propagation follows the same principle in a scale model as it does in a full-scale room. Through this method, it is possible to test different solutions towards energy efficiency and visual comfort. To verify the trustworthiness of scale modeling, a comparison between illuminance measurements in a scale model against a corresponding full-scale room was carried out. Two scale models with different daylighting systems were built to demonstrate the necessary procedures in utilizing scale models for daylighting studies: one of them had embedded a sidelighting system, and the other one, which held similar characteristics, comprised also a lightshelf. Nevertheless, the full-scale room was selected taking into consideration the simplicity of its geometry and the easiness of the access for the measurement procedures. The conclusions demonstrate that in order to reach trustworthy results, it is necessary to construct scale models in a precise way. Furthermore, its recommended to measure the illuminance under diverse sky conditions, enabling the evaluation of average daylighting performance within long terms.

O presente trabalho se propõe a analisar o método para avaliação da iluminação natural, utilizando os modelos físicos reduzidos como ferramenta, com o intuito de avaliar os aspectos quantitativos e qualitativos da luz. Foi realizado um diagnóstico deste método mostrando suas qualidades e limitações. O uso de modelos físicos reduzidos é um dos métodos mais antigos de avaliação da iluminação natural. Este é um instrumento preciso, caso o modelo seja executado de forma correta, considerando-se que a propagação da luz segue os mesmos princípios tanto em um modelo físico reduzido, como em um edifício em escala real. Através deste instrumento, torna-se possível testar as diversas soluções em busca da eficiência energética e do conforto visual. Para verificar o grau de confiabilidade dos resultados através da aplicação deste método foi feita uma comparação entre medições da iluminância em um modelo físico reduzido e medições realizadas em um ambiente real correspondente. Com o objetivo de demonstrar os procedimentos necessários para o uso de modelos físicos reduzidos no estudo da iluminação natural, foram feitas medições em dois modelos com estratégias de iluminação diferenciadas. Um deles possui iluminação natural unilateral, ao passo que, o segundo possui as características da abertura unilateral semelhante ao primeiro, porém, com a inclusão de uma prateleira de luz. Já o ambiente real foi selecionado devido à simplicidade de sua geometria e a facilidade de acesso para a realização das medições. As conclusões demonstram que para alcançar resultados confiáveis é necessário construir os modelos com precisão, sendo recomendável medir a iluminância dos mesmos sob diversas condições de céu, para que desta forma seja possível avaliar o desempenho médio da iluminação natural por um longo período. / The present work considers the analysis of scale models for daylighting evaluation, aiming at investigating quantitative and qualitative aspects of light. A diagnosis of scale modeling was carried out, showing its strengths and limitations. Scale modelling is one of the oldest methods for daylighting evaluation. It is also a precise instrument, when properly constructed, considering that light propagation follows the same principle in a scale model as it does in a full-scale room. Through this method, it is possible to test different solutions towards energy efficiency and visual comfort. To verify the trustworthiness of scale modeling, a comparison between illuminance measurements in a scale model against a corresponding full-scale room was carried out. Two scale models with different daylighting systems were built to demonstrate the necessary procedures in utilizing scale models for daylighting studies: one of them had embedded a sidelighting system, and the other one, which held similar characteristics, comprised also a lightshelf. Nevertheless, the full-scale room was selected taking into consideration the simplicity of its geometry and the easiness of the access for the measurement procedures. The conclusions demonstrate that in order to reach trustworthy results, it is necessary to construct scale models in a precise way. Furthermore, its recommended to measure the illuminance under diverse sky conditions, enabling the evaluation of average daylighting performance within long terms.

In today’s competitive market, it is essential to be innovative and creative for an industry to sustain. Industry need to introduce new products to the market. Engineering idea generation plays a vital role in the development of new products. This research study is focused on the engineering idea generation. The representations of ideas have an important impact on the idea generation process. Design concepts may be represented in a variety of forms like sketches, physical models or computer based models. The goal of this research is to understand how these various representations affect design cognition. In this thesis, three studies showing the effects of two different representations in the idea generation process are presented. The first study focuses on the effects of physical models in engineers’ design cognition. This preliminary study investigates two different hypotheses: (1) Physical models supplement and improve designer’s mental models and (2) Physical models induce design fixation. The results show that physical models supplement the designer’s mental models but fail to enhance them. No evidence of design fixation is observed. The second and third studies investigate the effects of computer-based idea generation software on design cognition. The research questions investigated in this study are: (1) How does the use of this software tool assist design cognition? (2) How can the software interface be improved so that designers can generate ideas more easily? To answer these questions, a between-subjects idea generation experiment is conducted. In the experiment, the participants are asked to generate ideas to solve a design problem with and without the software. The results show that participants who generated ideas with the help of the software tool have less quantity of ideas compared to the control group. This may be due to the design fixation induced by the concepts presented. In the third study, the opinions of the participants for the improvements of the software interface are collected. Results show that participants do not have any preference of one way of clustering the concepts over the other. The results of this study also provide creative input for the future improvement of the software.

10th IFAC Symposium on Robot Control International Federation of Automatic Control September 5-7, 2012. Dubrovnik, Croatia

Afin d’évaluer la sûreté d’ASTRID (Réacteur à Neutrons Rapide refroidi au sodium), les transitoires accidentels sont actuellement étudiés avec des codes de calculs déterministes coûteux en temps de calcul, comme SIMMER-III ou SAS-SFR. En complément de ces études, le CEA a entrepris le développement d’outils de calculs analytiques simulant les différents phénomènes physiques régissant ces transitoires. Ces outils permettent, compte-tenu de leur robustesse et des faibles temps de calculs, de prendre en compte par une approche probabiliste les incertitudes et d’analyser de manière statistique les résultats. Ce traitement s’avère en effet indispensable afin de tenir compte des incertitudes physiques et de la variabilité des scénarios de déroulement du transitoire accidentel. In fine, les études réalisées avec ce type d’outils, couplant une modélisation analytique de la physique à un traitement statistique des résultats, fourniront des informations quantitatives sur les marges de sûreté, vis-à-vis de critères donnés.Le développement et la validation de l’outil dédié aux transitoires de perte de débit primaire non protégé (ULOF - Unprotected Loss Of Flow), résultant du déclenchement des pompes primaires sans reprise de secours ni chute des barres de contrôle, fait l’objet de cette thèse. Cet outil a été nommé MACARENa (Modélisation de l'ACcident d'Arrêt des pompes d'un Réacteur refroidi au sodium). Au cours de cette thèse, seule la phase primaire de l’accident a été traitée.Le début de cette phase, enclenchée par la réduction du débit primaire, est gouverné par le couplage entre la thermohydraulique et les contre-réactions neutroniques. Le code MACARENa simule, selon les conditions initiales, l’établissement de la convection naturelle monophasique ou la stabilisation de l’ébullition dans la partie haute du cœur. Si l’écoulement est instable, l’excursion de débit conduisant à l’assèchement des aiguilles puis à leur dégradation est aussi modélisée. A la suite d’un tel transitoire, l’outil calcule la fusion et la relocalisation des gaines et du combustible ainsi que l’entraînement d’acier liquide par les vapeurs de sodium et le possible bouchage de l’assemblage par des matériaux resolidifiés, avant de suivre l’évolution de bains fondus qui conduisent à la rupture des tubes hexagonaux. Les mouvements de matériaux induisent aussi des effets neutroniques complexes qui sont traités dans la modélisation.Les modélisations effectuées pour construire l’outil MACARENa ont été validées sur des expériences à effets séparés (thermohydraulique ou de dégradation) et des résultats issus de code déterministes.Finalement, des études de propagation d’incertitudes et d’analyses de sensibilité sont réalisées avec cet outil afin d’illustrer son intérêt vis-à-vis de la démonstration de sûreté. / Within the framework of the Generation IV Sodium-cooled Fast Reactor (SFR) R&D program of CEA (French Commissariat à l’Energie Atomique et aux Energies Alternatives), safety in case of severe accidents is assessed.Such transients are usually simulated with mechanistic codes (such as SAS-SFR and SIMMER III). As a complement to these codes, which give reference accidental transient calculations, a new physico-statistical approach is currently followed by the CEA; its final objective being to derive the variability of the main results of interest for safety. This approach involves a fast-running description of extended accident sequences coupling physical models for the main phenomena to advanced statistical analysis techniques. It enables to perform a large number of simulations in a reasonable computational time and to describe all the possible bifurcations of the accident transient.In this context, this PhD work presents the physical tool (models and results assessment) dedicated to the initiation and primary phases of an Unprotected Loss Of Flow accident (i.e. until the end of sub-assemblies degradation and before large molten pools formation). The accident phenomenology during these phases is described and illustrated by numerous experimental evidences.It is underlined that the features of the new heterogeneous core concept (called CFV of the French ASTRID prototype) leads to different kinds of ULOF transients than those occurring in the previous past homogeneous cores (SuperPhenix, Phenix...). Indeed, its negative void effect drops the nuclear power when sodium heats-up and possibly boils. This enables three types of ULOF transients characterized by various core final states; the first two types leading to final coolable core states in natural circulation flow (the first one in single phase, the second one in stabilized two-phase flow) whereas the core undergoes a flow excursion followed by sub-assemblies degradation in the last type. In this study, a particular attention is paid to stabilize boiling occurrence which leads to minimize severe accident consequences.The phenomena occurring during the various ULOF transients are modelled in accordance to the level of details required to catch all the possible bifurcations of the transient. The tool coupled different (2D, 1D and 0D) models of thermics, thermo-hydraulics, core degradation (material melting and motions) and neutronics. The assumptions associated to these models are highlighted, discussed and validated. The physical tool capability of simulating the various realistic ULOF transients (without boiling, with stabilized boiling or flow excursion after boiling) is demonstrated by comparisons to experimental results (GR19, SCARABEE experiments) and to mechanistic simulations (CATHARE2 and SIMMER III).Parametric studies are then carried out on two variables: the fuel burn-up and the model of neutronic feedbacks. They underline the important influence of these parameters on the transient and the final core state. Finally, a preliminary sensitivity analysis (2000 simulations) is performed on 26 uncertain parameters (linked to initial core configuration, accident features, model uncertainties and radial nodalization). The variability of the final core state is underlined and quantified; only around 25% of cases lead to core degradation. The main influent parameters on transient phenomena are also identified, enabling to prioritize core design and safety studies.In the future, this tool will be used for safety-informed design and stability analyses of fast reactor systems, allowing to emphasize the main dominant phenomena and trends of significance for safety assessment.

Made available in DSpace on 2014-06-11T19:24:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-18Bitstream added on 2014-06-13T18:52:37Z : No. of bitstreams: 1 mauricio_rm_me_ilha_prot.pdf: 7189412 bytes, checksum: 165c0a934d87bdea5e70b44e57f92b0a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O principal objetivo do trabalho foi desenvolver o estudo de ligações diretas entre paredes de blocos de concreto em escala real e reduzida 1A. Foram realizados ensaios de resistência à compressão axial e medidas as deformações em blocos, prismas e paredes nas duas escalas. Também foram montadas paredes em forma de H assentadas sobre bases de concreto armado. Estas foram construídas de 2 formas: na primeira, chamada de PRl, foram construídas 3 (três) unidades de modo que a parede central não possuísse apoio em sua base, com isso, todo o carregamento aplicado foi transferido para as abas. Na segunda forma, chamada PH2, foram montadas 3 (três) unidades, e ,nestas, a parede central ficou apoiada em sua base, dessa maneira, observou-se os efeitos de transferência de carga entre paredes, simulando uma estrutura real, onde geralmente todas as paredes da edificação são apoiadas em outras paredes ou em vigas baldrames. Na confecção dos corpos-de-prova, nas duas escalas em estudo, foi empregada uma argamassa industrializada usada comercialmente. O carregamento foi introduzido de forma centrada, e as deformações foram medidas através de relógios comparadores e de extensômetros elétricos. Para a análise dos resultados foram empregados testes estatísticos, validando estatisticamente as conclusões. Também foi empregada uma análise através de elementos finitos, simulando os ensaios experimentais realizados, comparando-se os resultados e readequando o modelo numérico. Os resultados obtidos permitiram uma avaliação da eficiência dos modelos numéricos empregados e os ajustes necessários nos mesmos, o entendimento da forma de transferência das ações verticais entre as paredes interligadas e as correlações entre as escalas estudadas. / The main objective ofthis research was to develop a study of direct bond (stretcher bond) connections between walls of concrete blocks in real and 1:4 small-scale. In order to know the mechanical properties, it was accomplished shear and axial strength tests where it was also measured the strain in blocks, prisms and walls for both scales. It was executed walls in the H form supported by reinforced concrete base. These walls were done in two different ways, the first was called PRI, (with 3 specimens) it had no support in its central wall base, thus forcing that alI the load imposed to it was transferred to the lateral walIs throughout the connections. The second kind, which was called PH2, with also 3 specimens, was entirely support in its base. This was done in order to observe the load transference effects among walls simulating conventional structures, where all the walls are support over other walls or foundation beams. The specimens in both scales were made using industrialized mortar commercially used. The load was centralized imposed and strains were measurements by electrical displacement gages and strain gages. Statistical tests were used in the result analysis, statistically validating the conclusions. A finite element analysis was also used attempting to simulate the accomplished experimental tests, being this analytical model compared to the experimental results and then, by retrofitting the numerical analysis approaching their results. The obtained results allowed: an evaluation of the efficiency of the numeric models employed and the necessity of retrofitting the analysis; the comprehension in the way of transference of the vertical actions between the interlinked walls; and the correlations among the studied scales.

Neste trabalho são abordados dois aspectos relacionados com modelos físicos fraturados: o primeiro, referido à resistência, é abordado através da avaliação de ensaios triaxiais em modelos fraturados pelo critério empírico de resistência de Hoek-Brown, e por análise numérica através do Código Universal de Elementos Distintos (UDEC). O segundo, referido a modos de ruptura, é abordado através da simulação em termos de deformabilidade e resistência de modelos fraturados e a simulação de taludes de diferentes alturas com o intuito de estudar a influência do tamanho do bloco no modo de ruptura. Ambos aspectos estão baseados nos resultados experimentais de Brown (1970) e de Singh (1997). A influêcia do tamanho do bloco no modo de ruptura foi estudada utilizando RMR89\", levando em consideração a escala do maciço (altura do talude). Através de análises numéricas preliminares e de um processo de retroanálises, foi simulado o comportamento mecânico dos modelos fraturados referidos. A avaliação da resistência aplicando o critério de resistência empírica de Hoek-Brown mostrou resultados coerentes quando comparados com os resultados experimentais de Brown (1970). Através de RMR89\" foi possível observar a influência do tamanho do bloco nos modos de ruptura e na estabilidade dos taludes de diferentes alturas. / This works treats about two aspects related to jointed physical models: one related to strength, by back-analyzing data using the Hoek-Brown criterion by means of numerical analyses with the Universal Distinct Element Code (UDEC). The record refers to failure modes, is analyzed by means of numerical simulations taking into account deformability and strength of jointed physical models, as well as the simulation of slopes in jointed rock masses. Slopes of different heigths and different block sizes were analyzed to investigate scale effects. The analyses were made taking experimental results obtained by Brown (1970) and Singh (1997). The influence of the block size was studied using RMR89\", taking the rock mass scale into consideration. Strength evaluation adopting Hoek-Brown empirical strength criterion proved consistent with Brown\'s model test results. By means of RMR89\" the influence of the block size could be analyzed on failure models and in the stability of slopes with different heights.

O objetivo deste trabalho é apresentar informações sobre o uso de modelos físicos na indústria cerâmica como parte integrante do método de projeto e identificar as possibilidades de utilização de tecnologias digitais nesse processo, verificando possíveis contribuições para o design. Esta é uma pesquisa qualitativa, que se utiliza de procedimentos adotados em estudos de casos múltiplos, a partir da investigação de duas indústrias de cerâmica para cada um dos setores fabris: louça de mesa, louça sanitária, cerâmica decorativa/ ornamental, revestimentos cerâmicos, telhas e blocos estruturais. Foram realizadas pesquisas bibliográficas e de campo, por meio de visitas a indústrias cerâmicas, a representantes de equipamentos de tecnologias digitais, a centros de pesquisa nacional e internacional e a instituições que possuem os equipamentos digitais para obtenção de modelos físicos. Os modelos físicos são muito utilizados em projetos de design durante as fases de desenvolvimento de produto e servem para gerar, analisar e selecionar as alternativas propostas, fornecendo respostas a problemas que surgem através de testes e simulações que devem ser adequados às questões e informações que se pretende coletar. Tradicionalmente, o processo de desenvolvimento de modelos físicos na indústria cerâmica requer conhecimentos técnicos e depende de muito treinamento e habilidades manuais dos modeladores. O uso de tecnologias digitais é muito difundido em outros segmentos da indústria, devido à capacidade de transformar rapidamente e com precisão modelos virtuais computadorizados em modelos físicos. Para compreender como cada segmento da indústria cerâmica utiliza os modelos físicos evidenciaram-se suas especificidades, quanto aos aspectos de configuração dos produtos e limitações dos materiais e dos processos de fabricação. Analisaram-se as seguintes tecnologias digitais: processos de prototipagem rápida, usinagem CNC e escaneamento 3D. Este trabalho demonstrou como processos analógicos tradicionais podem ser complementados e/ou substituídos para obtenção dos modelos físicos a partir da inserção de tecnologias digitais nesse processo. / The purpose of this study is to present information on the use of physical models in the ceramic industries as an integral part of the project method as well as identify the possibilities of using digital technologies in this process for possible contributions to the design. This is a qualitative research, which uses procedures adopted in multiple case studies, from the results of a survey on two ceramic industries for each of the industrial sectors: tableware, sanitary ware, decorative / ornamental ceramic tiles, tiles, ceramic roofing and building blocks. Bibliographical and field researches were conducted through visit to ceramics industries, representatives of digital technology equipment, national and international research centers and institutions that own digital equipment to obtain physical models. The physical models are widely used in design projects during the phases of product development and serve to generate, analyze and select the proposed alternatives, in order to provide answers to problems which arise through tests and simulations and that must be appropriated to the issues and information that are intended to be collected. Traditionally, the development process of physical models in the ceramic industry requires technical knowledge and depends on training and manual skills of the modelers. The use of digital technologies is widespread in other segments of the industry due to the ability to turn quickly and accurately, virtual computer models into physical models. In order to understand how each segment of the ceramic industry uses physical models, their specificities had to be evidenced, regarding aspects of product configuration and limitations of materials and manufacturing processes. The following digital technologies were analyzed: rapid prototyping process, CNC machining and 3D scanning. This work demonstrated how the traditional analog processes can be complemented and/or substituted in order to obtain physical models through the insertion of digital technologies in this process.