Dissertations / Theses: 'Equivalent materials'

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Robertson, Maida Christine. "Psychometrically Equivalent Arabic Monosyllabic Word Recognition Materials." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1508.pdf.

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Elzokra, Ahmed Adel Emhemed. "Damage mechanisms in porous building materials due to salt crystallization: formulation of equivalent materials for masonry." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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An equivalent material approach is presented for the computation of the elastic properties of brick masonry and for the assessment of salt crystallization in masonry structures. A stacked brick-mortar system consisting of a series of parallel layers which behave elastically is introduced. This is extended such that masonry with two sets of mortar joints (bed and head joints) can be represented by an equivalent homogeneous orthotropic elastic material. It is then extended to salt deteriorated brick masonry by including salt crystals induced within the pores. In terms of the elastic properties of the brick and mortar, as well as relative thicknesses, expressions for the equivalent material's elastic properties are derived. The mechanical properties of salt deteriorated masonry are computed in terms of effective porosity and saturation ratio. Using this derivation, the stresses in the brick-and-mortar joints are calculated for a masonry wall partial deteriorated by salt and subjected to thermal stress variation.

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Caldwell, Meghan Elizabeth. "Development of Psychometrically Equivalent Speech Audiometry Materials for Testing Children in Mongolian." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3139.pdf.

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Anderson, Melissa Dawn. "Development of Psychometrically Equivalent Speech Recognition Threshold Materials for Native Cebuano Speakers." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6154.

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While there is a clear and immediate need for reliable speech audiometry materials to evaluate the speech recognition threshold (SRT), these recorded materials are not available in Cebuano, a language of the Philippines with 15.8 million speakers. The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Cebuano trisyllabic words for use in measuring the SRT. To create the SRT materials, common Cebuano trisyllabic words were digitally recorded by a male talker of Cebuano and presented for evaluation to 20 native speakers of Cebuano with normal hearing. Based on psychometric performance, a set of 21 trisyllabic words with a psychometric function slope >7%/dB that allowed threshold adjustments to the pure tone average were selected and digitally adjusted. The resulting mean psychometric function slopes at 50% for the 21 SRT trisyllabic materials was 10.2%/dB. The results of the current study are comparable to those found in other languages. Digital recordings of the trisyllabic words are available on compact disc.

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Williams, Chela. "Psychometrically Equivalent Thai Monosyllabic Word Recognition Materials Spoken by Male and Female Talkers." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2717.pdf.

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Conklin, Brooke Kristin. "Psychometrically Equivalent Cantonese Bisyllabic Word Recognition Materials Spoken by Male and Female Talkers." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2139.pdf.

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Newman, Jennifer Lane. "Development of Psychometrically Equivalent Speech Recognition Threshold Materials for Native Speakers of Samoan." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2214.

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The speech recognition threshold (SRT) is an important measure, as it validates the pure-tone average (PTA), assists in the diagnosis and prognosis of hearing impairments, and aids in the identification of non-organic hearing impairments. Research has shown that in order for SRT testing to yield valid and reliable measures, testing needs to be performed in the patient's native language. There are currently no published materials for SRT testing in the Samoan language. As a result, audiologists are testing patients with English materials or other materials not of the patient's native language. Results produced from this manner of testing are confounded by the patient's vocabulary knowledge and may reflect a language deficit rather than a hearing loss. The present study is aimed at developing SRT materials for native speakers of Samoan to enable valid and reliable measures of SRT for the Samoan speaking population. This study selected 28 trisyllabic Samoan words that were found to be relatively homogeneous in regard to audibility and psychometric function slope. Data were gathered on 20 normal hearing native speakers of Samoan and the intensity of each selected word was adjusted to make the 50% performance threshold of each word equal to the mean PTA of the 20 research participants (5.33 dB HL). The final edited words were digitally recorded onto compact disc to allow for distribution and use for SRT testing in Samoan.

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Taylor, Brandon Brian. "Development of Psychometrically Equivalent Speech Audiometry Materials for Measuring Speech Recognition Thresholds in Native Tagalog Speakers." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3348.

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In addition to the use of pure-tones for testing hearing, speech signals are highly valuable diagnostic tools for identifying and evaluating hearing impairment. Speech audiometry involves the implementation of such signals in the measurement of hearing acuity. One aspect of speech audiometry involves assessment of the speech recognition threshold (SRT) which evaluates an individual's ability to hear and understand speech. While live speech has been used in the past to assess SRT, recorded materials are preferred and have been shown to be advantageous over live speech. High-quality digitally recorded speech audiometry materials have been available in English for some time, but assessment of individuals using speech materials from a language that they do not speak natively has been shown to be both inadequate and inaccurate. Speech audiometry materials have recently become available in many languages. Currently, however, there are no known published recordings for assessment of SRT in the Tagalog language. The goal of this study was to develop psychometrically equivalent speech audiometry materials for measuring speech recognition threshold in Tagalog. During this study Tagalog words were initially recorded by a native speaker selected for accent and vocal quality. The words were reduced down to 90 words to be evaluated in the study. Each of the 90 trisyllabic words were evaluated at 2 dB increments from -10 to 16 dB HL by 20 native Tagalog speakers, all having normal hearing. Based on the results, 34 trisyllabic Tagalog words were selected based on their familiarity to native listeners, relative homogeneity with regards to audibility and psychometric function slope. Each word was then adjusted to make the 50% performance threshold equal to the mean PTA of the 20 research participants (4.3 dB HL). The final edited words were then digitally recorded onto compact disc for distribution and for use in assessing SRT in native Tagalog speakers worldwide.

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TOMIMASU, SUMIE. "Desenvolvimento de material simulador de tecido humano a partir do latex de borracha natural vulcanizado com radiacao gama." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10879.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Darle, Maria, Saga Lindqvist, and Bezawit Tsegai. "The climate impact of different building systems : A study regarding materials in residential buildings and their environmental impact." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-390024.

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This report was done on behalf of Uppsala municipality with the aim to investigate how much the CO2-equivalent emissions differ between different building systems during the construction phase, considering the different choice of material used in the frames. Several multi-family houses with different building systems were therefore studied and compared by using previous LCA from collected climate reports regarding each construction project. Different scenarios of the residential development in Uppsala until year 2050, including multi- and single-family houses, were further on brought forward. The impact that the choice of material had on the climate was then studied by comparing the scenarios with the climate goals set up by Uppsala municipality regarding the construction sector. This was discussed in order to investigate whether Uppsala municipality would reach the climate goals or not. The conclusion of the study is that the building systems with wooden frames in general release less CO2-equivalent emissions than the ones with concrete frames. One of the reasons for this is that the production of the materials has different amounts of waste and the fact that concrete consists of cement, which causes a lot of emissions during the production of the material. Another part of the report was to investigate if climate improved concrete could decrease the CO2-equivalent emissions from building systems with concrete frames. This was done by doing a case-study, where parts of the concrete frame for one of the building systems were replaced, which resulted in a small decrease of the emissions. It is however, in a larger perspective, important to reduce the emissions as much as possible and there is still room to continue the improvement of concrete.

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Joana, Geórgia Santos. "Estudo do alcance de elétrons com energias entre 110 eV e 50 KeV." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2006. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=47.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Existe um grande número de estudos que examina a dependência entre energia e alcance para elétrons com energias desde alguns keVs até centenas de MeVs. Porém, a descrição quantitativa do transporte de elétrons de baixa energia é um problema complexo, especialmente devido à não disponibilidade de dados confiáveis para as seções de choque dos diferentes mecanismos por meio dos quais elétrons interagem com a matéria. Uma vez que os modelos analíticos de transporte de elétrons ou são incompletos ou apresentam dificuldades até o momento intransponíveis, os códigos de Monte Carlo têm sido a alternativa adotada nestas abordagens e são hoje extensivamente utilizados. É sabido que na interação de radiações ionizantes com o tecido vivo podem ocorrer danos severos em estruturas nos níveis celular e sub-celular. Uma vez que a transferência de energia de radiações ionizantes para o meio ocorre predominantemente através da interação dos elétrons secundários produzidos por esta com o material, existe um interesse especial na determinação da relação entre energia inicial e alcance para elétrons; especialmente os de baixa energia. Neste trabalho é estudada a relação entre energia inicial e alcance em meio biológico para elétrons com energias entre 110 eV e 50 keV. Para tal foi utilizado o código de Monte Carlo PENELOPE com o qual foram realizadas simulações do transporte de elétrons de baixa energia (110 eV a 50 keV) e dos fótons secundários gerados por estes provenientes de uma fonte monoenergética isotrópica localizada no interior de um meio tecido equivalente homogêneo. A partir daí, as grandezas de interesse foram calculadas e analisadas.

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Shrestha, Alina. "Fatigue Testing and Data Analysis of Welded Steel Cruciform Joints." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1670.

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In this study, ABS Publication 115, “Guidance on Fatigue Assessment of Offshore Structures” is briefly reviewed. Emphasis is on the S-N curves based fatigue assessment approach of non-tubular joints, and both size and environment effects are also considered. Further, fatigue tests are performed to study the fatigue strength of load-carrying and non-load-carrying steel cruciform joints that represent typical joint types in marine structures. The experimental results are then compared against ABS fatigue assessment methods, based on nominal stress approach, which demonstrates a need for better fatigue evaluation parameter. A good fatigue parameter by definition should be consistent and should correlate the S-N data well. The equivalent structural stress parameter is introduced to investigate the fatigue behavior of welded joints using the traction based structural stress approach on finite element models of specimens, and representing the data as a single Master S-N curve.

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ALTRAN, SILVANA C. "Substituição dos componentes xenobióticos, empregados no meio de cultura para manutenção de queratinócitos humanos, por similares de origem humana." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10026.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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RODAS, ANDREA C. D. "Desenvolvimento de membranas como compostos dermo-epidermicos." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11161.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Riesco, Refoyo Javier. "Development of battery models for on-board health estimation in hybrid vehicles." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211680.

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Following the positive reception of electric and hybrid transport solutions in the market, manufacturers keep developing their vehicles further, while facing previously undertaken challenges. Knowing the way lithium-ion batteries behave is still one of the key factors for hybrid electric vehicles (HEVs) development, especially for the requirements of the battery management system during their operation. Hence, this project focuses on the necessity of robust yet reasonably simple and cost-effective models of the battery for estimating the health status during the operation of the vehicles. With this aim, the procedure and models to calculate the state-of-health (SOH) indicators, internal resistance and capacity, are proposed and the results discussed. Two machine-learning based models are presented, a support vector machine (SVM) and a neural network (NN), together with one equivalent circuit model (ECM). The data used for training and validating the models comes from testing the batteries in the laboratory with standard performance tests and real driving cycles along the battery lifespan. However, data sets measured in actual heavy-duty vehicles during their operation for three years is also analysed and compared. With respect to this matter, a study of the battery materials, behaviour and operation attributes is carried out, highlighting the main aspects and issues that affect the development of the models. The inputs for the models are signals that can be measured on-board in the vehicles, as current, voltage or temperature, and other derived from them as the state-of-charge (SOC) calculated by the internal battery management unit. Time-series of the variables are used for simulation purposes. The management of signals and implementation of the models is done in the environment of Matlab-Simulink, using some of its in-built functions and other specifically developed. The models are evaluated and compared by means of the normalized root mean squared error (NRMSE) of the voltage output profile compared to that of the tested batteries, but also the error of the internal resistance calculations calculated from the voltage profile for the three models, and the internal parameters in case of the ECM. While despite the difficulties faced with the data, the models can eventually perform accurate estimations of the resistance, the results of the capacity estimations are omitted in the document due to the lack of useful information derived. Nevertheless, the calculation procedure and other considerations to take into account regarding the capacity estimation and data sets are undertaken. Finally, the conclusions about the data used, battery materials and methods evaluated are drawn, laying down recommendations as to design the performance tests following the conditions of the driving cycles, and indicating the higher general performance of the SVM respect the other two methods, while asserting the usefulness of the ECM. Moreover, the battery with NMC material composition is observed to be easier to predict by the models than LFP, also showing different evolution of its internal resistance.

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Sanghavi, Chaitanya. "FETI methods for acoustic problems with porous materials." Thesis, Le Mans, 2020. http://www.theses.fr/2020LEMA1021.

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E présent travail traite de la modélisation numérique de traitements acoustiques à grande échelle en utilisant des méthodes de décomposition de domaine (MDD). Les principaux objectifs de la thèse sont triples : Premièrement, un choix de méthode de décomposition de domaine (DDM) approprié pour résoudre des problèmes de Helmholtz homogènes et hétérogènes à grande échelle est fait. Deux variantes différentes des méthodes FETI, à savoir FETI-2LM et FETI-H, sont mises en œuvre et comparées. Un choix approprié de la méthode est fait. Ensuite, une nouvelle stratégie de résolution est appliquée au DDM choisi pour résoudre de nombreux traitements acoustiques. Cette stratégie vise à réduire les coûts de calcul associés aux étapes. Troisièmement, des stratégies alternatives sont examinées pour réduire les coûts associés aux coûts itératifs du DDM. Une nouvelle méthode FETI-2LM à deux niveaux est formulée pour réduire les coûts des évaluations successives des revêtements. Une autre stratégie de recyclage basée sur l'utilisation des valeurs propres les plus influentes est examinée pour la méthode FETI-2LM. Un choix approprié de ces méthodes est fait. La modélisation numérique des traitements acoustiques à l'aide de méthodes efficaces nécessite des coûts de calcul importantss dans la phase de conception. Ce travail fournit une contribution permettant de résoudre ce problème à l'aide de la DDM
Sound absorbing materials such as foams are widelyused in many industrial and domestic applications toabsorb undesirable sound. One needs to perform many calculations to get desirable properties of thetreatment using optimization strategies.The state-of-the-art computational models requireprohibitively high computational time. Theproblematic of this PhD is to reduce thecomputational time for such models to speed updesign calculations.This document is a synthesis of the work carried outin this direction. The problem is addressed usingDomain Decompostion methods (DDM). It consists ofsplitting the original problem into small parts referredto as subdomains. A partial solution is computed onthese subdomains to match the global continuity inthe domain of interest. Different DDM methods are benchmarked in termsof performance and scalability , specific for porousmaterials. Any DDM consists of two major costs, thefactorization of the subdomains and iterative part forthe global convergence. A novel factorizationstrategy is implemented and applied in 2D and 3Dto demonstrate savings in time compared toconventional approaches. In the second part, themethod is further improved to reduce the iterativecosts for a series of calculations.A final workflow is proposed to make thecomputationa cost of these models afforable withinindustrial timeframes

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Fernandes, Victor Santoro. "Desenvolvimento de método de análise de materiais equivalentes ao tecido humano por simulação Monte Carlo." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-12122017-130310/.

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Materiais radiologicamente equivalentes ao tecido humano (Tissue Equivalent Material - TEM) têm a finalidade de evitar exposição injustificável à radiação de pacientes e são amplamente utilizados no controle de qualidade de equipamentos de diagnóstico por imagem. Esses materiais devem ser caracterizados para que se possa confiar em sua semelhança, em termos de suas propriedades de interação com a matéria, aos tecidos que substituem. Uma das maneiras de caracterizar os materiais é verificando se o espectro transmitido através deles se assemelha ao transmitido através do tecido que substituem. O método Monte Carlo (MC) é uma ferramenta útil no processo de caracterização dos TEM pois pode evitar o processo custoso de realizar experimentos de transmissão de raios-X. Esse trabalho investigou a aplicabilidade do método MC à caracterização de TEM de tecido mamário (bTEM) utilizados no controle de qualidade de equipamentos de mamografia. Para verificar a aplicabilidade do método MC, uma série de resultados de simulações foi comparada a resultados experimentais. Espectros de raios X transmitidos foram comparados diretamente através da média de seus resíduos reduzidos (Mean Weighted Squared Residuals - MWSR). Comparações foram feitas através de grandezas derivadas dos espectros. Essas grandezas foram: as camadas semi-redutoras (primeira e segunda), a energia média e a energia efetiva. Foi realizada uma discussão acerca da eficiência de cada uma dessas comparações, através da estimativa do poder de cada teste de hipótese. Os experimentos de transmissão de radiação foram realizados em duas instalações, no Laboratório de Dosimetria das Radiações e Física Medida da Universidade de São Paulo, onde foi utilizado um tubo de raios X com anodo de tungstênio adaptado para qualidades de feixe utilizadas em aplicações mamográficas, e no Centro de Desenvolvimento de Tecnologia Nuclear da Comissão Nacional de Energia Nuclear, equipado com um mamógrafo clínico com anodos de tungstênio e molibdênio. Diversas condições experimentais foram variadas para assegurar a robustez das conclusões, tais como as combinações anodo/filtro, os materiais constituintes dos bTEM, suas glandularidades, espessuras e as tensões de pico. Os espectros sem nenhuma atenuação (0 mm) também foram medidos e utilizados nas comparações. Os espectros foram medidos com um detector comercial de CdTe. Dosímetros termoluminescentes foram utilizados para estimar a dose depositada em diversas regiões do bTEM, e esses resultados foram também comparados às simulações. Além da estimativa do nível de exatidão alcançado pelo código de MC nas referidas condições, também se concluiu que o teste de hipótese do MWSR teve o maior poder estatístico, de 0,996. O MWSR foi o teste que demonstrou a compatibilidade dos espectros medidos o maior número de vezes. Esse teste aceitou 48% dos pares de espectros contra 40% de aceitação do teste da primeira camada semi-redutora, que foi o segundo teste com maior aceitação.
man radiologically tissue equivalent materials (TEM) have the purpose of avoiding unjustifiable irradiation of patients; they are largely used in the quality control of image diagnostic equipment. These materials must be characterized so that their similarity to the tissues they simulate can be relied upon, regarding their properties of interaction with radiation. One way of characterizing the materials is by checking the resemblance between their transmitted spectrum to the one of tissue they simulate. The Monte Carlo (MC) method is a useful tool in the TEM characterization process, since it may avoid the realization of costly experiments of transmitted X-ray spectrometry. MC may even dismiss preliminary experiments. This work investigated the applicability of the MC method to the characterization of breast tissue TEM (bTEM) used in the quality control of mammography equipment. To evaluate the applicability of the MC method, a series of simulation results was compared to experimental data. Transmitted spectra were directly compared through their mean weighted squared residues (MWSR), and by the comparisons of spectra derived quantities, as it is commonly done in the literature. These quantities were: the half value layers (first and second), the mean energy and the effective energy. A discussion about the efficiency of each one of these comparisons was made by estimating the statistical power of each hypothesis test. The radiation transmission experiments were carried out in two facilities: at the Laboratory of Radiation Dosimetry and Medical Physics of the University of São Paulo, where a tungsten anode X-ray tube adapted to mammographic applications was used. The rest of the experiments was done at the Nuclear Technology Development Center of the National Commission of Nuclear Energy, equipped with a clinical mammographic equipment with anodes composed by tungsten and molybdenum. Several experimental conditions were varied to ensure the robustness of the conclusions, such as the anode/filter combination, the bTEM constituent materials, their glandularities, thicknesses and peak voltages. Spectra with no attenuation (0 mm) were also measured and used in the comparisons. The spectral measurements were done with a commercial CdTe detector. Thermo-luminescent dosimeters were used to estimate the dose deposited at several regions inside the bTEM, and these results were also compared to simulations. In addition to estimating the level of accuracy achieved by the MC code in the mentioned conditions, it was also concluded that the highest statistical power was scored by the MWSR and it was of 0.996. The MWSR was also the test which attested this compatibility of the measured spectra the most. It accepted 48% of the spectra pair against 40% acceptance of the first half value layer test, which was the second test with most acceptance.

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VENEZIANI, GLAUCO R. "Desenvolvimento de um objeto simulador "Canis Morphic" utilizando impressora 3D para aplicação em dosimetria na área de radioterapia veterinária." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27967.

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O aumento na longevidade humana fez surgir uma série de doenças com a idade; em contrapartida o avanço da medicina possibilitou o diagnóstico precoce e o tratamento de várias doenças antes incuráveis. Esse cenário atual estendese também aos animais domésticos (cães e gatos - PETs) que dobraram sua expectativa de vida nas últimas décadas, fato que os humanos demoraram séculos para alcançar. Do mesmo modo que os humanos, esse aumento na longevidade dos animais veio acompanhado de doenças relacionadas com a idade, entre elas o câncer. Uma das terapias utilizadas atualmente no tratamento do câncer é a radioterapia, técnica que utiliza a radiação ionizante para destruir as células tumorais (volume-alvo) com mínimo prejuízo aos tecidos circunvizinhos sadios (órgãos de risco). Essa técnica exige a realização periódica de testes de controle de qualidade, incluindo a dosimetria com a utilização de objetos simuladores equivalentes ao tecido, de modo a verificar a dose de radiação recebida pelo paciente em tratamento e compará-la posteriormente com a dose de radiação calculada pelo sistema de planejamento. A rápida expansão do mercado de impressoras 3D abriu caminho para uma revolução na área da saúde. Atualmente os objetos simuladores por impressão 3D estão sendo usados em planejamentos de Radioterapia para a localização espacial e mapeamento das curvas de isodose, realizando, assim, um planejamento mais personalizado para cada campo de radiação, além da confecção de implantes dentais, customização de próteses e confecção de bólus. Diante do exposto esse trabalho projetou e desenvolveu um objeto simulador chamado de \"Canis Morphic\" utilizando uma impressora 3D e materiais tecido-equivalentes para a realização dos testes de controle de qualidade e otimização das doses na área de Radioterapia em animais (cães). Os resultados obtidos demonstraram-se promissores na área de criação de simuladores por impressão 3D, com materiais de baixo custo, para aplicação no controle de qualidade em Radioterapia veterinária.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Elliott, Lewis Roland. "Physical activity in natural environments : importance of environmental quality, landscape type and promotional materials." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/22411.

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Physical inactivity and disconnection from natural environments threatens human health. However, research has demonstrated that natural environments potentially support health-enhancing physical activity which could confer greater physical and mental health benefits than physical activity in other types of environment. This thesis approached the study of physical activity in natural environments through three related pieces of research. Firstly, an experimental study was carried out to explore how the presence of litter in beach environments affected psychophysiological responses to exercise. Responses to exercise did not differ in littered and clean conditions but there was evidence that order effects influenced findings. Visual attention to the two scenes differed, but did not mediate differences in psychophysiological responses. Secondly, analysis of a national dataset was undertaken to explore the form and quantity of physical activity conducted within natural environments in England. A series of linear regressions revealed that higher-intensity physical activities occurred in countryside environments, but more total energy expenditure occurred in coastal environments. Thirdly, a quantitative content analysis of brochures which promote recreational walking in natural environments was conducted which investigated their use of persuasive behavioural messages. These brochures omitted behavioural techniques which may be effective at motivating inactive individuals to walk. Extending this, an online survey tested whether improving brochure content heightened intentions to walk in natural environments. By designing content based on the theory of planned behaviour, the intentions of inactive individuals to undertake walking in natural environments were increased. The findings from this thesis demonstrate that the protection of natural environments is vital for preserving and promoting active recreation and could contribute to population-level increases in physical activity with theory-based promotion in the future.

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Sjödin, Mattias. "Investigating Particle Cracking in Single- and Polycrystalline Nickel-Rich Cathodes using In Situ Impedance Spectroscopy." Thesis, Uppsala universitet, Strukturkemi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-449968.

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State-of-the-art Li-ion cathode materials are based on LiMO2 (M=Ni, Mn, Co) layered transition metal oxides (denoted NMC) with Ni-rich composition because of their high specific capacity. Yet, these materials suffer from poor capacity retention due to crack formation during de-/lithiation cycling. Particle cracking leads to exposure of new electrode surface which leads to Li-inventory loss, increased side reactions, and electric disconnection. Quantification of the extent of cracking is therefore desirable, especially during in situ whilst cycling of the Li-ion cell. Herein, we evaluate and improve an analytical methodology based on electrochemical impedance spectroscopy (EIS) in order to estimate the changes in electrochemically active surface area of both poly- and single-crystalline Ni0.8Mn0.1Co0.1(NMC811) active materials. A transmission-line model (TLM) applied to both non-blocking and blocking electrode condition was utilized in order to deconvolute and interpret the acquired experimental data. Fits of the complex TLM equivalent-circuits to the impedance spectra was facilitated by developing a global stochastic iterative function based on local multivariate optimization. Impedance analysis during short- term cycling showed that the single-crystalline NMC811 suffered from less particle cracking and side reactions compared to polycrystalline NMC811, which was also confirmed from post-mortem gas adsorption analysis. A novel approach to estimate the extent of particle cracking in commercial Li-ion cells by utilizing an empirically strong positive correlation between the charge-transfer capacitance and resistance was proposed. The work presented herein demonstrates the unique prospects of the EIS methodology in the development and research of future rechargeable batteries

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VALERIANO, CAIO C. S. "Emprego de simulação computacional para avaliação de objetos simuladores impressos 3D para aplicação em dosimetria clínica." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28015.

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O propósito de um objeto simulador é representar a alteração do campo de radiação provocada pela absorção e espalhamento em um dado tecido ou órgão de interesse. Suas características geométricas e de composição devem estar próximos o máximo possível aos valores associados ao seu análogo natural. Estruturas anatômicas podem ser transformadas em objetos virtuais 3D por técnicas de imageamento médico (p. ex. Tomografia Computadorizada) e impressas por prototipagem rápida utilizando materiais como, por exemplo, o ácido poliláctico. Sua produção para pacientes específicos requer o preenchimento de requisitos como a acurácia geométrica com a anatomia do individuo e a equivalência ao tecido, de modo que se possa realizar medidas utilizáveis, e ser insensível aos efeitos da radiação. O objetivo desse trabalho foi avaliar o comportamento de materiais impressos 3D quando expostos a feixes de fótons diversos, com ênfase para a qualidade de radiotherapia (6 MV), visando a sua aplicação na dosimetria clínica. Para isso foram usados 30 dosímetros termoluminescentes de LiF:Mg,Ti. Foi analisada também a equivalência entre o PMMA e o PLA impresso para a resposta termoluminescente de 30 dosímetros de CaSO4:Dy. As irradiações com feixes de fótons com qualidade de radioterapia foram simuladas com o uso do sistema de planejamento Eclipse™, com o Anisotropic Analytical Algorithm e o Acuros® XB Advanced Dose Calculation algorithm. Além do uso do Eclipse™ e dos testes dosimétricos, foram realizadas simulações computacionais utilizando o código MCNP5. As simulações com o código MCNP5 foram realizadas para calcular o coeficiente de atenuação de placas impressas expostas a diversas qualidades de raios X de radiodiagnóstico e para desenvolver um modelo computacional de placas impressas 3D.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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El, Assami Yassine. "Homogénéisation en viscoélasticité linéaire non-vieillissante par la méthode de l'inclusion équivalente : application aux matériaux cimentaires." Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1051/document.

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La prédiction du comportement à long terme des matériaux cimentaires est un enjeu majeur pour contribuer à l'étude de la durabilité des structures précontraintes. Le présent travail porte sur l'utilisation de la méthode de l'inclusion équivalente, approche d'homogénéisation multi-échelle simplifiée, pour la prédiction du fluage dans ces matériaux. Le fluage est modélisé par la viscoélasticité linéaire sans vieillissement. La méthode de l'inclusion équivalente permet de contourner certaines difficultés et limitations que présentent les approches classiques. Pour les matériaux cimentaires, fortement hétérogènes, les approches multiéchelles classiques sont ou bien numériquement lourdes et très complexes à mettre en œuvre, ou bien pas suffisamment détaillées pour prendre en compte les spécificités d'une microstructure. La méthode de l'inclusion équivalente présente un juste-milieu et permet de calculer des microstructures simplifiées de type matrice-inclusions et de fournir des estimations ou des bornes sur le comportement homogénéisé. Sous sa forme variationnelle, la méthode de l'inclusion équivalente n'a jusqu'alors été mise en œuvre que pour des inclusions de forme sphérique. Le présent travail propose d'étendre cette méthode à des inclusions de forme ellipsoïdale dont la variation de l'élancement permet de modéliser de nouveaux éléments asphériques tels que les fissures, les fibres et les cristaux de portlandite. Cette complexification de la géométrie a un impact sur le temps de calcul, qui est amplifié dans le cadre du fluage. Le second volet du travail porte alors sur l'extension de la méthode de l'inclusion équivalente à la viscoélasticité linéaire sans vieillissement par l'intermédiaire de la transformée de Laplace-Carson. Une méthodologie efficace (tant du point de vue de la précision que de celui du temps de calcul) est finalement proposée pour effectuer l'inversion numérique de cette transformée
The prediction of long-term behaviour of cementitious materials is a major concern which contributs to the study of the durability of prestressed structures. This work focuses on the use of the equivalent inclusion method, simplified multi-scale homogenization approach, for the prediction of creep in these materials. Creep is modelled by the non-ageing linear viscoelasticity. The equivalent inclusion method overcomes certain difficulties and limitations posed by conventional approaches. For cementitious materials (highly heterogeneous), conventional multi-scale approaches are, either digitally heavy and complex to implement, or not sufficiently detailed to take into account the specificities of a microstructure. The equivalent inclusion method presents a middle way and allows the calculation of simplified matrix-inclusion type microstructures and to provide estimates or bounds on the homogenized behaviour.Under its variational form, the equivalent inclusion method has, up to now, been implemented only for spherical inclusions. This work proposes to extend this method to ellipsoidal inclusions whose variation of slenderness allows the modelling of new aspheric elements such as cracks, fibers and portlandite crystals. Such enrichment of the geometry has an impact on the computation time, that is amplified in the context of creep. The second aspect of the work then applies to the extension of the equivalent inclusion method to the non-ageing linear viscoelasticity by means of the Laplace-Carson transform. An effective methodology (both from the viewpoint of precision and calculation time) is finally proposed to perform the numerical inversion of this transform

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Nyqvist, Björn. "Produktion av digitala läromedel för elever med blindhet : En problematiserande studie om tillgängliggörande." Thesis, Stockholms universitet, Specialpedagogiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-154748.

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Målet med denna studie är att belysa hur läromedelsproducenter och personal vid SPSM:s läromedelsavdelning talar om hur den pågående digitaliseringen av läromedelsmarknaden påverkar tillgång till och tillgänglighet i läromedel för elever med blindhet. En fråga som också fokuseras är ansvaret för att denna elevgrupp får möjlighet till delaktighet genom tillgång till samma läromedel som övriga elever. Studiens resultat är användbara för SPSM, förlag, skolhuvudmän och skolor. Den använda metodansatsen är diskurspsykologi och metoden kvalitativa intervjuer. Totalt har fem enskilda intervjuer gjorts på fem större förlag samt fyra intervjuer med sammanlagt nio personer på Specialpedagogiska skolmyndighetens läromedelsavdelning, varav tre var gruppintervjuer. Genom att analysera det som sägs tydliggörs deltagarnas beskrivning av tillgång till läromedel, ansvar och ansvarsfördelning för tillgången mellan olika aktörer samt konsekvenser för elever med blindhet. Studien visar på förändrade krav som ställs på samhällets stöd och på läromedelsproducenter för att tillgodose tillgången till läromedel för elever med blindhet som läser punktskrift till följd av den digitala utvecklingen. Behov av ändrade arbetsformer och ett ökat samarbete mellan aktörer och inom verksamheter för att möta de nya kraven synliggörs. I studien framkommer dilemman som uppstår mellan kostnader för tillgängliggörande, målgruppsstorlek och olika verksamheters förutsättningar i mötet mellan offentlig verksamhet och kommersiella aktörer. I studien tydliggörs att det är skolan som har ansvar för en likvärdig utbildning vilket inkluderar ansvaret för tillgänglighet i de läromedel som används. En förskjutning hos skola och skolhuvudmän mot centrala upphandlingar av digitala läromedel ses som trolig vilket ställer krav på beställarkompetens samtidigt som oro uttrycks för om den kompetensen finns. Det behövs mer forskning om konsekvenser av den ökade mängden digitala läromedel för elever med blindhet. Exempel på intressanta frågor är hur det pedagogiska arbetet påverkas och vilka effekter digitaliseringen får för eleven.
The aim of this study is to highlight how producers of teaching materials and the department for adapting teaching materials at The National Agency for Special Needs Education and Schools (SPSM) regard the impact of the ongoing digitization of the teaching aids market with focus on access to and accessibility of teaching materials for students with blindness. Another issue is the responsibility for this group of students to participate through accessibility to the same teaching materials as their peers. The results of the study can be of use to SPSM, publishers, local education authorities and schools. The methodology approach is discursive psychology and the method used is qualitative interviews. In total five separate interviews were carried out at five larger publishing companies, and four interviews with, in total, nine informants at SPSM, the department for adapting teaching materials, were performed, whereof three were group interviews. By analyzing what has been said the participants’ descriptions of accessibility to teaching aids are clarified, and so is responsibility and division of responsibility between different actors, and furthermore the consequences for students with blindness. The study illuminates changed requirements for support from society and teaching materials producers to satisfy the need of teaching materials for students with blindness reading braille, all due to the digitization of the current area. Demands to meet with new needs for changed work models and for an increased cooperation between actors, and within relevant agencies, are highlighted. In the study appear dilemmas arising between the following factors: expenses for accessibility, size of target group and conditions for different actors at a crossroads of government controlled businesses and commercial actors. The study clarifies the school’s responsibility for equivalence in education, which includes accessibility to teaching materials in use. There is a likelihood of a shift with schools and local educational authorities towards central procurement of digital teaching materials, which calls for client expertise. There is also concern about whether that expertise exists. Further research is needed on the increasing amount of digital teaching materials and its consequences for students with blindness. Interesting questions are, among others, how the pedagogical work is affected and which will be the impact on the student.

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Smith, Austin Gregory. "Characterization and Quantification of Early Stages for Organic Coatings Applied on AA2024/AA7075 by Correlating Frequency Domain Approach in Real Time." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399125698.

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Mnasri, Faiza. "Étude du transfert de chaleur et de masse dans les milieux complexes : application aux milieux fibreux et à l’isolation des bâtiments." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0169/document.

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Le contexte énergétique international impose de nouvelles orientations au secteur du bâtiment neuf ou en rénovation. Toute nouvelle solution doit être techniquement efficace et respectueuse pour l’environnement. Il s'agit dans ce travail de thèse de réaliser une étude numérique et expérimentale de matériaux de construction biosourcés liés au contexte transfrontalier Lorrain (France-Belgique- Luxembourg). En effet, ce travail intègre une partie du projet européen « Ecotransfaire » mené pour le développement d'une filière durable propre aux éco-matériaux. La sélection des matériaux selon une liste de critères à la fois scientifiques, géographiques et environnementaux a permis de répondre à notre problématique en s'orientant vers l'intégration des matériaux biosourcés pour leurs aspects favorables à l'environnement et à l’efficacité énergétique du bâtiment. Intégrés au bâtiment, ces matériaux sont sujets à plusieurs phénomènes de transfert de chaleur et de masse. Dans un premier temps et pour mieux appréhender ces phénomènes, un modèle de transfert couplé de chaleur, d'air, d'humidité (HAM transfers) est utilisé pour simuler le comportement hygrothermique d’un matériau en bois massif à structure supposée homogène. Ce modèle, mis en œuvre et résolu par la méthode des éléments finis, a été validé par des résultats analytiques retenus dans la littérature. L'étude de sensibilité du modèle au couplage, aux dimensions dans l'espace, aux conditions aux limites et aux variabilités des paramètres d'entrée est également présentée. Une des difficultés de l’utilisation de ce modèle réside dans la prise en considération de l'aspect fortement hétérogène de certains matériaux. Ainsi, dans ce travail, nous proposons une approche de caractérisation d'un composite lignocellulosique hétérogène de structure poreuse. En effet ce matériau est composé de deux constituants bien connus dans le domaine de l’industrie de construction: Le bois et le ciment. Le bois est incorporé sous forme de granulats avec des formes et des tailles irrégulières et le ciment est utilisé comme un liant. Le travail réalisé permet de remonter aux propriétés intrinsèques équivalentes de ce matériau (conductivité thermique et perméabilité à la vapeur) à l’aide des techniques de micro-tomographie. La méthodologie suivie consiste à la détermination de la structure d'échantillon par une prise d'images à l'échelle microscopique. Une fois la structure de l’échantillon générée, une reconstruction de la représentation bidimensionnelle précède la génération de la structure tridimensionnelle à l'aide d’un outil numérique qui permet de déterminer les propriétés équivalentes des domaines reconstruits en 3D. La perméabilité et la conductivité thermique équivalentes sont les deux propriétés évaluées dans cette configuration. Ces deux propriétés dépendent fortement de la porosité et de la distribution des pores dans la phase continue (la phase solide). De plus la composition de ce matériau et les fractions volumiques de chacun de ses constituants influent sur la formation de sa microstructure et par conséquent sur ses propriétés de transferts thermiques et hydriques. L'ensemble des connaissances développées dans ce travail permet une piste sérieuse pour l'élaboration d'un éco-matériau à propriétés contrôlées pour des usages spécifiques dans la construction et la rénovation
International energy context requires a new orientation to the building sector as in construction or in renovation. Any new solution must be technically efficient and environmentally acceptable. In this thesis, the object is to achieve a numerical and experimental analysis of a building biobased materials. Some of these materials are included from the study of a transborder project to the Lorraine region (France, Belgium and Luxembourg). Indeed an Ecotransfaire project was included in this work. This project has been oriented to the development of a sustainable eco materials chain. A process of analysis has been established in order to select the materials candidates on the basis of scientific, geographical and environmental criteria. The answers are moving towards the integration of bio-based materials. These materials are subject of several heat and mass transfers phenomena. So understanding these mechanisms within a building material has been achieved firstly. This resulted on a coupled model of heat transfer, air, moisture experienced by the HAM model. This model is applied to a wooden building material whose its structure is assumed homogeneous. Then, this model was implemented and solved by the finite element method. Its numerical solution is validated by analytical results available in the literature. The study of sensitivity of the model coupling, dimensions in space, the boundary conditions and the variability of input parameters is also presented. One of the difficulties of using this model is the case of heterogeneous materials. Thus, in this work, we propose an approach of characterization of a heterogeneous lignocellulosic composite material with a porous structure. In fact, this material is composed of two components: Wood and cement. The wood is presented by a shapes aggregates with irregulars sizes and the cement is considered as the binder in the composition. The object was to predict its equivalent intrinsic properties (thermal conductivity and vapor permeability) by using the micro-tomography techniques.The methodology consists to determine the structure of the sample by taking images at the microscopic scale. Once the structure of the sample is generated, we will conduct from a reconstruction of the two-dimensional representation to a three dimensional structure by using a numerical tool which determines the equivalent properties of the 3D reconstructed domain. The permeability as well as the equivalent thermal conductivity are the two properties evaluated in this configuration. These two properties are strongly depend to the porosity and to pore distribution in the continuous phase (the solid one). Moreover the composition of the material and the volume fractions of each components influence the formation of microstructure and consequently the thermal and hydric transfers

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Derhak, Maxim W. "Spectrally Based Material Color Equivalency| Modeling and Manipulation." Thesis, Rochester Institute of Technology, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3722035.

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A spectrally based normalization methodology (Wpt normalization) for linearly transforming cone excitations or sensor values (sensor excitations) to a representation that preserves the perceptive concepts of lightness, chroma and hue is proposed resulting in a color space with the axes labeled W, p, t. Wpt (pronounced “Waypoint") has been demonstrated to be an effective material color equivalency space that provides the basis for defining Material Adjustment Transforms that predict the changes in sensor excitations of material spectral reflectance colors due to variations in observer or illuminant. This is contrasted with Chromatic Adaptation Transforms that predict color appearance as defined by corresponding color experiments. Material color equivalency as provided by Wpt and Wpt normalization forms the underlying foundation of this doctoral research. A perceptually uniform material color equivalency space (“Waypoint Lab" or WLab) was developed that represents a non-linear transformation of Wpt coordinates, and Euclidean WLab distances were found to not be statistically different from ΔE*₉₄ and ΔE₀₀ color differences. Sets of Wpt coordinates for variations in reflectance, illumination, or observers were used to form the basis of defining Wpt shift manifolds. WLab distances of corresponding points within or between these manifolds were utilized to define metrics for color inconstancy, metamerism, observer rendering, illuminant rendering, and differences in observing conditions. Spectral estimation and manipulation strategies are presented that preserve various aspects of “Wpt shift potential" as represented by changes in Wpt shift manifolds. Two methods were explored for estimating Wpt normalization matrices based upon direct utilization of sensor excitations, and the use of a Wpt based Material Adjustment Transform to convert Cone Fundamentals to ”XYZ-like" Color Matching Functions was investigated and contrasted with other methods such as direct regression and prediction of a common color matching primaries. Finally, linear relationships between Wpt and spectral reflectances were utilized to develop approaches for spectral estimation and spectral manipulation within a general spectral reflectance manipulation framework – thus providing the ability to define and achieve “spectrally preferred" color rendering objectives. The presented methods of spectral estimation, spectral manipulation, and material adjustment where utilized to: define spectral reflectances for Munsell colors that minimize Wpt shift potential; manipulate spectral reflectances of actual printed characterization data sets to achieve colorimetry of reference printing conditions; and lastly to demonstrate the spectral estimation and manipulation of spectral reflectances using images and spectrally based profiles within an iccMAX color management workflow.

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Ram, Gokul, and Vishnu Harikrishnan. "INFLUENCE OF CARBON CONTENT AND COOLING CONDITIONS ON THE THERMAL CONDUCTIVITY AND TENSILE STRENGTH OF HIGH SILICON LAMELLAR GRAPHITE IRON." Thesis, Tekniska Högskolan, JTH, Material och tillverkning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-51152.

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Much study has been carried out to determine the properties of Lamellar Graphite Iron (LGI) or grey iron and their relations to factors such as the cooling rate, the dendrite morphology, the pouring temperature, and so on. However, there hasn’t been much comprehensive study on the properties of LGI outside the generally used and accepted composition, with 1 to 3% Silicon. The scope of this study is to measure and evaluate the thermal conductivity and tensile strength of LGI, for a higher concentration of Si and different carbon contents. The concentration of Si aimed for was 4% but the concentration obtained after spectroscopy was between 4.1% to 4.15%. There are two hypereutectic, one near-eutectic and three hypoeutectic samples considered and these six chemical compositions were cast under different cooling conditions . The cooling time has been varied by providing different molds of 30mm, 55mm, and 80mm diameter cylinders respectively, for all the six sample compositions. The microstructure analysis carried out studies the segregation of Si, the graphite morphology, primary austenite morphology. These factors are then compared to the thermal and tensile behavior measured in this study. It can be observed that the thermal conductivity studied in the present work has a direct correlation for a higher Si content and tends to be greater than the thermal conductivity values observed from other studies with lower content Of Si. However, the conductivity shows an inverse relation with the cooling rate and is maximum for the samples with the lowest cooling rate. The tensile strength, on the other hand, seems to have a lower value than that observed in previous studies for LGI with 1 to 3% Si, but shows a direct correlation with the cooling rate. The mean area fraction of dendrites obtained and the mean interdendritic hydraulic diameter is also measured and their influence on the properties are also studied. The addition of more Si has greatly favored the thermal behavior positively but has also reduced the tensile strength.

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Abdelli, Wassim. "Modélisation du rayonnement électromagnétique de boîtiers de blindage par sources équivalentes : application aux matériaux composites." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112093.

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La modélisation de matériaux composites est un domaine d’étude qui bénéficie d’un intérêt croissant. En effet, la vulgarisation de l’utilisation de tels matériaux nécessite le développement de nouveaux modèles afin de mieux comprendre leur comportement. L’industrie automobile et aéronautique s’efforce d’optimiser le choix des matériaux en fonction des spécificités de chaque application, afin de réduire la masse des équipements et de leur assurer de meilleurs caractéristiques mécaniques et thermiques. Les matériaux composites se sont aussi présentés comme une éventuelle alternative au métal pour le rôle de blindage électromagnétique. Leur généralisation dans cette optique se heurte néanmoins à une relative méconnaissance de leur comportement électromagnétique. A cet effet, il est nécessaire de disposer de méthodologies permettant d'évaluer l'efficacité de blindage de boîtiers en matériaux composites et de cerner les différents mécanismes et paramètres correspondants.Par ailleurs, le déploiement de ces matériaux alternatifs à plus grande échelle est freiné par d'autres contraintes liées essentiellement à la difficulté de l'analyse électromagnétiques 3D complète de systèmes complexes abritant des boîtiers en matériaux composites. En effet, la complexité topologique de certains composants complique considérablement leur insertion dans les outils de simulation électromagnétique existants. De plus, le rapport d'échelle entre les différents niveaux (système, boîtiers composites, cartes, circuits, composants) est trop important ; cette disparité d'échelle complexifie considérablement la discrétisation géométrique de l'ensemble. L'association de ces différentes contraintes conduisent à des difficultés réelles aux quelles les ingénieurs CEM sont confrontés. C'est pourquoi il est nécessaire de développer des modèles performants permettant de faciliter l'analyse 3D du système hôte complet. Ce travail de thèse s'est donc réparti sur deux volets :- dans un premier temps, nous présentons une méthodologie de calcul de l'efficacité de blindage des boîtiers en matériaux composites, afin d'évaluer la potentialité de ces matériaux en termes de blindage électromagnétique et de cerner les principaux facteurs qui y contribuent.- dans un second temps et dans l'objectif de fournir une approche permettant de mettre les systèmes électroniques complexes intégrant des boîtiers de blindage composites en conformité avec les exigences strictes de CEM, nous proposons une méthodologie de modélisation des rayonnements électromagnétiques. Cette modélisation (à base d’algorithmes génétiques) permet de remplacer les dispositifs ou les boîtiers rayonnants (composites notamment) par un ensemble de dipôles élémentaires. Le modèle équivalent, de type "boîte noire", est ainsi représentatif de l’ensemble de la structure en termes de rayonnement électromagnétique en hautes fréquences et est facilement intégrable dans le maillage de structures hôtes. Ce modèle multipolaire fournit des prédictions spatiales et fréquentielles du champ électrique et magnétique permettant entre autres de calculer l'efficacité de blindage du boîtier dans l'espace, donnant ainsi un moyen de quantifier son impact perturbateur sur son environnement. D'autre part, cette approche permet de simplifier l'analyse 3D d'un système complet abritant des boîtiers composites en contrôlant le comportement EM à tous les niveaux : système, boîtiers, cartes, circuits et composants
The modeling of composite materials is a domain of study which benefits of increasingly interest. Indeed, the popularization of the use of such materials requires the development of new models in order to better understand their behavior. The automotive and aerospace industry strives to optimize material selection based on the specificities of each application in order to reduce the weight of the equipment and to provide better mechanical and thermal characteristics. Composite materials have been also presented as a potential alternative to metals for the role of electromagnetic shielding. Their generalization in this context is nevertheless hampered by a relative lack of knowledge of their electromagnetic behavior. For this purpose, it is necessary to have methodologies to evaluate the shielding effectiveness of composite enclosures and identify the different corresponding mechanisms and parameters.Moreover, the deployment of these alternative materials on a larger scale is hindered by other constraints related mainly to the difficulty of complete 3D analysis of complex systems including composite enclosures. In fact, the topological complexity of certain components greatly complicates their integration into existing electromagnetic simulation tools. Moreover, the scale ratio between the different levels (system, composite enclosures, electronic card, circuit, component) is too large ; This disparity of scale complexifies considerably the geometrical discretization of the entire system. The combination of these different constraints leads to real difficulties to which EMC engineers face. That is why it is necessary to develop efficient models to facilitate the 3D analysis of the complete host system.This work is therefore divided in two sections :- In a first time, we present a methodology to calculate shielding effectiveness of composite enclosures of electronic equipment. The goal is to evaluate the potential of these materials in terms of electromagnetic shielding and to identify the main contributing factors.- In a second time, and in order to ensure compliance of complex electronic systems incorporating composite shielding enclosures with the stringent requirements of EMC, we propose a modeling methodology of electronic devices radiation. This modeling (based on genetic algorithms) allows to replace the radiating devices and enclosures (especially composites) by a set of elementary dipoles. The equivalent model, "black box" type, is thus representative of the entire structure in terms of high frequency electromagnetic radiation and is easily integrable in the mesh of host structures. This multipolar model provides spatial and frequency predictions of the electric and magnetic field, enabling among others to calculate the shielding effectiveness of the radiating enclosure in space, thereby giving a way to quantify its disruptive impact on its environment. Moreover, this approach allow to simplify the 3D analysis of a complete system comprising composite enclosures by controlling the EM behavior at all levels: system, enclosures, cards, circuits and components

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Filho, Nilson Magagnin. "Placas laminadas em materiais compostos de fibras longas: propriedades termoelásticas dos materiais constituintes; propriedades equivalentes das lâminas; critérios de ruptura e análise pelo método dos elementos finitos." Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-02042018-115346/.

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Os materiais compostos de fibras longas vêm se destacando entre o conjunto de novos materiais em desenvolvimento, com larga aplicação na indústria e também na construção civil. Elabora. se aqui um texto introdutório no campo das placas laminadas constituídas de lâminas em compostos de fibras longas. A partir das propriedades dos materiais constituintes, fibra e matriz, são apresentadas as teorias para a determinação das propriedades equivalentes das lâminas. A teoria da anisotropia elástica é formulada e a teoria dos laminados em flexão é desenvolvida. Conclusões com respeito ao acoplamento de esforços em tais estruturas são mostradas. Os modos básicos de ruptura da fibra, matriz e da interface entre ambas são apresentados, bem como os modos básicos de delaminação. Alguns critérios de ruptura são mostrados, assim como um critério de escoamento. Ao fim alguns exemplos ilustram a análise pelo método dos elementos finitos de tais estruturas feita por programa disponível em literatura, com a implementação de subrotina para análise da temperatura.
Long fiber composite materials have been standing out among the group of new materials in development with wide industrial application and also in civil construccion. Here is elaborated an introductory text in laminated plates field constituted of long fiber composite laminae. Starting from constituent materials properties, fiber and matrix, the theories for determination of laminae equivalent properties are presented. Elastic anisotropy theory is formulated and the bending laminated theory is developed. Conclusions about the coupling efforts in such structures are showed. Fiber, matrix and the interface between both failure basic modes are presented, as well as delamination basic modes. Some failure criteria are showed, as well as a yielding criteria. At the end some examples illustrate the finite element method analysis of such structures made by available literature programme with temperature analysis subroutine implementation.

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Edwards, Micael Cuin. "A Method for Determining Weight Reduction through Material Substitution in Automotive Structures of Equivalent Stiffness." MSSTATE, 2002. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11302001-165029/.

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The benefits of lighter auto bodies are discussed, and aluminum is compared to steel as an alternative material for auto body construction. The concept of a structural index, lambda, is developed using the simple example of a hollow beam of wall thickness, t, with a cantilever load case. It is shown that the bending stiffness, K, of the beam can be defined as a function of t^lambda, that 1 < lambda < 3, and that lambda can be used to predict the weight savings from material substitution where stiffness is held constant. It is then demonstrated that lambda can be used to predict the weight savings from material substitution in the more complex cases of the joints of a light truck cab.

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Eder, Alexandre Ernesto. "Influência do teor de nitrogênio na trefilação de aço equivalente ao ABNT 1013." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/6806.

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Neste trabalho, estudou-se o efeito do N no comportamento de ruptura de arames durante o processo de trefilação de um aço equivalente ao ABNT 1013. Inicialmente, caracterizaram-se as propriedades mecânicas do mesmo após cada passe de trefilação, ou seja, da bitola inicial até o diâmetro final do produto. Após este estudo inicial, escolheu-se três aços com teores de nitrogênio de 96ppm, 122ppm e 166ppm para ensaios de tração à quente no intuito de verificar um possível envelhecimento, desempenho no ensaio de dobramento e também para avaliar a performance no processo produtivo, ou seja, a sua trefilabilidade. Estes aços foram ensaiados nas temperaturas ambiente, 50, 100 e 200°C. O resultado de trefilabilidade foi medido através do número de interrupções devido a quebra de arames dividido pela tonelada de material produzido. Os resultados obtidos no presente estudo nos apontam que, conforme aumenta o teor de N presente no aço, se tem um aumento nas propriedades mecânicas e também na susceptibilidade ao rompimento durante o teste de dobramento, além de um aumento no número de quebras por tonelada de material produzido, o que vai de acordo com a experiência operacional de perda na trefilabilidade. Já em relação ao envelhecimento, foi observado que as alterações nas propriedades mecânicas não foram significativas o bastante para caracterizá-lo, levando em conta as referidas temperaturas, aço estudado e as condições de ensaios propostas no trabalho.

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Oliveira, Milton Paulo de. "Análise in vitro da citotoxicidade e proliferação celular em equivalentes de pele humana." Pontifícia Universidade Católica do Rio Grande do Sul, 2009. http://hdl.handle.net/10923/4495.

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Evaluation of in vitro cell behavior with biomaterials may shorten the stages required to certify its compatibility. The methods proposed by ISO 10993 standards allow the ordered, and a rational scale to determine the materials biocompatibility regarding its cytotoxicity. This standardization may help to compare different biomaterials used in experimental studies, and the production of new and safe materials, contributing to the development of tissue bioengineering. Human skin equivalents frequently used may have their cytotoxicity mediated by changes in mitochondrial function, determined by MTT test. The cytotoxicity of Human Skin Equivalents (HSEs) Veloderm® and Biopiel® in NIH-3T3 cell line fibroblasts culture (4. 5 × 104 cells/well) were assayed in the presence of different extracts concentrations according to the ISO 10993 standards per 24, 48 and 72 hours, and the degree of cytotoxicity was determined by the MTT test. There was a difference in cytotoxicity between VL and BP on 48 hours cell cultures when 10% extracts was used (p=0. 01). A difference was also detected regarding BP concentrations in 48 hours cultures that shown a reduction in cytotoxicity with increasing extracts concentrations (10% to 60%) (p=0. 014). VL extract concentrations on 72 hours cultures also shown a difference in cytotoxicity, when in cytotoxicity with increasing extracts concentrations (60% to 100%) (p=0. 041). According to ISO 10993 classifications, both extracts of HSE were defined as non-toxic (NT) suggesting a high biocompatibility of Veloderm® and Biopiel®. This hypothesis should be confirmed with complementary tests, although the colorimetric MTT test is an initial evaluation to rationalize the application of biomaterials in vivo and in clinical experimentation.
Introdução: Há uma grande necessidade de suprir a demanda por enxertos de pele autólogos humanos, fundamentais para tratamento de pacientes sujeitos as situações particulares como úlceras, queimaduras, traumas entre outras. Polímeros naturais e sintéticos têm sido desenvolvidos e empregados como biomaterias. A aplicação de testes visando avaliar o comportamento celular na presença do biomaterial in vitro poderá abreviar as etapas necessárias para atestar sua biocompatibilidade. A análise com as metodologias proposta pelas normas da ISO 10993 permite o estabelecimento de uma escala ordenada e racional para a biocompatibilidade dos materiais em função de sua citotoxicidade. Essa padronização poderá auxiliar na comparação de diversos biomateriais utilizados em estudos e, na produção de novas matérias, contribuindo para o desenvolvimento da bioengenharia dos tecidos. Os materiais analisados e utilizados como equivalentes de pele humana podem ter sua citotoxicidade mediada por alterações da função mitocondrial das células, determinada pelo teste de MTT. Objetivos: (1) Avaliar a citotoxicidade dos extratos dos Equivalentes de Pele Humana (EPH) Veloderm® e Biopiel® no cultivo de fibroblastos da linhagen celular NIH-3T3, através do teste colorimétrico de MTT; (2) classificação dos extratos puros dos EPH através de escala de citotoxicidade, de acordo com as normas da ISO 10993. Metodologia: Foram utilizados como substâncias-teste extratos de Equivalentes de Pele Humana (EPH) Veloderm® (VL) e Biopiel® (BP).Fibroblastos da linhagem NIH-3T3 foram semeados em três placas de cultural de 96 poços na concentração de 4,5 × 104 células por poço. As células foram cultivadas na presença de concentrações distintas dos extratos das substâncias-teste, obtidos segundo as normas da ISO 10993 por 24, 48, e 72 horas para a determinação do grau de citotoxicidade das substâncias-teste quando comparadas ao controle de positivo (CP) e negativo de citotoxicidade (CN), através do teste de MTT. Resultados: na comparação entre os Grupos (CN, CP, BP, VL), os dados mostraram que houve diferença significativa na citotoxicidade (p<0,001) no CP contra CN, BP e VL dos extratos puros de cultivo, nos diferentes tempos de exposição (24, 48 e 72 horas). Não houve diferença significativa da citotoxicidade do Grupo BP e VL contra CN. Houve diferença de citototoxicidade (p=0,01) quando extratos de 10% em cultura celular de 48 horas foram usados nos Grupos VL (17,4±1,4) e BP (14,5±0,6). Uma diferença também foi detectada na citotoxicidade (p=0,014) no Grupo BP em 48 horas de cultura, entre o extrato de 10% (14,5±0,6) contra os extratos de 60% (16,7±1,0) e 100% (17,0±1,3). O Grupo VL em cultura de 72 horas mostrou uma diferença na citotoxicidade (p=0,041) quando comparados os extratos de 60% (21,3±1,6) e 100% (17,5±2,1).A viabilidade celular dos extratos do Veloderm® e Biopiel® independente do tempo de exposição e concentração encontraram-se entre 75% e 100% na comparação com CN. Segundo a classificação baseado na ISO 10993, ambos os extratos puros de EPH foram definidos não tóxicos (NT). Conclusão: O conjunto dos resultados sugere alta biocompatibilidade dos EPHs testados; entretanto, o teste colorimétrico de MTT representa uma avaliação inicial, sendo importante seu papel na racionalização da experimentação in vivo e clínica dos biomateriais. Esta hipótese precisa ser confirmada com testes complementares segundo normas da ISO 10993.

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Al-wattar, Tahseen Abdulridha Ali. "Developing equivalent solid model for lattice cell structure using numerical approaches." Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1610335304435815.

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34

Camós, Andreu Carles. "Sensitivity of urban buildings to tunneling-induced settlements." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/287981.

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Tunneling construction represents an alteration to the distribution of soil pressures that will almost inevitably generate ground subsidence, which can endanger the adjacent buildings in urban areas. The risk of building damage can be substantially reduced with a comprehensive preliminary damage assessment during tunnel design phases, in combination with excavation techniques that minimize ground subsidence. The present research aims to increase the knowledge concerning the analytical and numerical techniques for building damage prediction related to tunneling. The thesis starts with the study of a real case of masonry building affected by the construction of the L9 metro line tunnel in Barcelona. Data available made possible to develop 2D and 3D numerical models of the building. The latter includes also the soil, the lining and interface models to simulate the contact between the building and the ground. The predicted crack patterns and opening widths in walls were verified by comparison to real damage reports. The case study also allowed a back analysis of the classical analytical prediction techniques based in the equivalent beam concept from Burland and Wroth. Analytical predictions of building damage are typically done for building walls aligned transversally or longitudinally with respect to the tunnel axis. These buildings are statistically representative, since many urban tunnels follow the tracks of avenues or streets. However, there is a significant number of buildings randomly aligned with respect to tunnel axes, in particular when using a Tunnel Boring Machine. For these buildings, the application of the classical analytical methodology can be done only with approximations, which can lead to unrealistic damage assessments. For this reason, a novel equation for the determination of ground strain has been developed. This equation allows the application of the classical settlement Gaussian profiles and the equivalent beam method in 3D, i.e. for buildings located in whichever position with respect to the tunnel axis. In addition, the model allows considering the position of the tunnel heading, which increases the realism of the settlement trough generated by tunnel construction. Another detected issue during the present research was the high sensitivity of both analytical and numerical damage predictions to certain parameters related to the characterization of ground. In the case of analytical predictions, the modeling of settlement troughs by Gaussian curves offers numerous mathematical advantages. However, the simplicity of this approximation leads to substantially different estimations of damage for small variations of the governing parameters. For this reason, the use of reliability-based methods can be useful for the assessment of building damage. In this way, the present thesis shows the development of a probabilistic model for the prediction of tunneling-induced damage. A procedure to determine the maximum allowable settlements that are used as monitoring threshold values of the construction process is also included. Furthermore, it is shown how the prediction of ground behavior and the allowable settlements can be updated with a Bayesian method by incorporating measurements made during the construction.
La construcció de túnels representa una alteració de la distribució de pressions del sòl que, de manera pràcticament inevitable, genera assentaments en superfície. Aquests poden provocar danys en edificis, especialment en zones urbanes. No obstant, aquest risc es pot reduir substancialment mitjançant la correcta predicció dels danys en les fases de disseny del túnel, juntament amb l¿ús de tècniques d'excavació que minimitzin els assentaments induïts. La present recerca aprofundeix en la metodologia de predicció de danys en edificis afectats per la construcció de túnels urbans. La tesi comença amb l'estudi d'un edifici real d'obra de fàbrica afectat per la construcció del túnel de la línia L9 del metro de Barcelona. Mitjançant les dades disponibles, s'han realitzat models numèrics en 2D i 3D de l'edifici. Aquest últim inclou a més el sòl, el túnel i un conjunt d'elements d'interfície que simulen el contacte entre l'edifici i el terreny. Els patrons de fissuració predits pel model han estat comparats amb aixecaments dels danys fets durant les obres. L'estudi d'aquest cas ha permès també l'aplicació i verificació de les tècniques de predicció de danys en edificis basades en el concepte de la biga equivalent ideat per Burland i Wroth durant la dècada dels 70. Les prediccions analítiques de dany en edificis es duen a terme generalment assumint els edificis posicionats transversalment o longitudinalment respecte l'eix del túnel. El nombre d'edificis que compleix aquesta hipòtesi és estadísticament representatiu, ja que molts túnels segueixen la traça dels carrers o les avingudes de les ciutats. Tot i així existeix un gran nombre d'edificis alineats arbitràriament respecte l'eix del túnel, especialment quan la construcció del túnel es realitza mitjançant l'ús de tuneladores (Tunnel Boring Machines - TBM). Per aquests edificis, l'aplicació de la metodologia analítica clàssica es pot efectuar només mitjançant aproximacions, la qual cosa pot implicar estimacions poc realistes dels danys. Per aquest motiu, s'ha desenvolupat una nova equació per al càlcul de la deformació del terreny. Aquesta equació permet l'aplicació dels perfils Gaussians d'assentament clàssics i del model de la biga equivalent en 3D, és a dir, en edificis ubicats en qualsevol posició respecte l'eix del túnel. A més, el model permet considerar la posició del front d'excavació, incrementant així el realisme del camp d'assentaments generat per la construcció del túnel. Un altre aspecte important detectat durant la recerca és l'extrema sensibilitat de les prediccions dels danys segons els valors dels paràmetres relacionats amb la caracterització del terreny. La modelització del camp d'assentaments mitjançant perfils Gaussians ofereix una sèrie d'avantatges matemàtics, però tot i així, la simplicitat del model comporta diferències notables en l'estimació dels danys si s'efectuen petites variacions dels paràmetres d'entrada. És per això que les tècniques de fiabilitat estructural poden ser útils per a l'estimació dels danys. En aquesta línia, la tesi mostra un model probabilístic per a la predicció dels danys provocats en edificis degut a la construcció de túnels. L'aplicació de tècniques de fiabilitat estructural permet a més la determinació dels llindars d'assentament que s'utilitzen durant el procés constructiu. En cas de tenir mesures prèvies d'assentaments de la zona d'estudi, es mostra també com el comportament del terreny i aquests valors llindars poden actualitzar-se a través d'un mètode Bayesià.

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35

Singh, Bhupinder. "Advanced Data Analysis Tools and Multi-Instrument Material Characterization." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6168.

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My dissertation focuses on (i) the development of new analysis tools and methodologies for analyzing X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) data, and (ii) the comprehensive characterization of materials (nanodiamonds) using a multi-instrument approach. Chapter 1 contains (i) a discussion of the two techniques I focused on most in my work: XPS and ToF-SIMS, (ii) a discussion of the common chemometrics techniques used to analyze data from these methods, and (iii) the advantages/rationale behind the multi-instrument characterization of materials. Chapter 2 describes various good practices for obtaining reasonable peak fits in XPS, which can also be applied to peak fitting data from different techniques. To address the issue of user subjectivity/bias in XPS peak fitting, I introduce two less biased mathematical functions for characterizing XPS narrow scans, namely the equivalent width (EW) and the autocorrelation width (AW). These functions are discussed in Chapters 3 and 4. In Chapter 5, I then introduce uniqueness plots as simple and straightforward graphical tools for assessing the quality of XPS peak fits and for determining whether fit parameters are correlated. This tool is extensively used in spectroscopic ellipsometry, and the mathematics behind it is known in XPS. However, to the best of my knowledge, this graphical tool has never been applied to XPS. ToF-SIMS data analysis is somewhat challenging due to the enormous amounts of data that are collected, and also the matrix effect in SIMS. This amount of information is significantly increased when depth profiles are performed on samples. Chapter 6 discusses a new chemometrics tool that I introduce for analysis of complex data sets, with emphasis on XPS and ToF-SIMS depth profiling data. The new approach is called the Information Content (IC) or entropy, which is adapted from Claude Shannon's work on Information Theory. Chapter 7 then contains a presentation of the comprehensive characterization of five nanodiamond samples used to manufacture particles for liquid chromatography. The advantages of a multi-instrument approach for material characterization and the lack of comprehensive material characterization in the literature are emphasized. To the best of my knowledge this is the most comprehensive characterization of nanodiamonds that has been reported in the literature. Chapter 8 presents conclusions of my work and future work. This thesis also contains six appendices. Appendix 1 contains an article from a scientific magazine that I wrote to highlight the importance and applications of the EW and AW to characterize XPS narrow scans. Appendices 2-5 are application notes I wrote on separations I performed on a nanodiamond based HPLC column. Finally, Appendix 6 describes the ToF-SIMS analysis of the tungsten species in the nanodiamond samples characterized in Chapter 7.

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36

Walker, Brooke. "Using the Stimulus Equivalence Paradigm to Teach Course Material in an Undergraduate Rehabilitation Course." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1879993801&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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37

Oliveira, Milton Paulo de. "An?lise in vitro da citotoxicidade e prolifera??o celular em equivalentes de pele humana." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2009. http://tede2.pucrs.br/tede2/handle/tede/1534.

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Introdu??o: H? uma grande necessidade de suprir a demanda por enxertos de pele aut?logos humanos, fundamentais para tratamento de pacientes sujeitos as situa??es particulares como ?lceras, queimaduras, traumas entre outras. Pol?meros naturais e sint?ticos t?m sido desenvolvidos e empregados como biomaterias. A aplica??o de testes visando avaliar o comportamento celular na presen?a do biomaterial in vitro poder? abreviar as etapas necess?rias para atestar sua biocompatibilidade. A an?lise com as metodologias proposta pelas normas da ISO 10993 permite o estabelecimento de uma escala ordenada e racional para a biocompatibilidade dos materiais em fun??o de sua citotoxicidade. Essa padroniza??o poder? auxiliar na compara??o de diversos biomateriais utilizados em estudos e, na produ??o de novas mat?rias, contribuindo para o desenvolvimento da bioengenharia dos tecidos. Os materiais analisados e utilizados como equivalentes de pele humana podem ter sua citotoxicidade mediada por altera??es da fun??o mitocondrial das c?lulas, determinada pelo teste de MTT. Objetivos: (1) Avaliar a citotoxicidade dos extratos dos Equivalentes de Pele Humana (EPH) Veloderm? e Biopiel? no cultivo de fibroblastos da linhagen celular NIH-3T3, atrav?s do teste colorim?trico de MTT; (2) classifica??o dos extratos puros dos EPH atrav?s de escala de citotoxicidade, de acordo com as normas da ISO 10993. Metodologia: Foram utilizados como subst?ncias-teste extratos de Equivalentes de Pele Humana (EPH) Veloderm? (VL) e Biopiel? (BP). Fibroblastos da linhagem NIH-3T3 foram semeados em tr?s placas de cultural de 96 po?os na concentra??o de 4,5 ? 104 c?lulas por po?o. As c?lulas foram cultivadas na presen?a de concentra??es distintas dos extratos das subst?ncias-teste, obtidos segundo as normas da ISO 10993 por 24, 48, e 72 horas para a determina??o do grau de citotoxicidade das subst?ncias-teste quando comparadas ao controle de positivo (CP) e negativo de citotoxicidade (CN), atrav?s do teste de MTT. Resultados: na compara??o entre os Grupos (CN, CP, BP, VL), os dados mostraram que houve diferen?a significativa na citotoxicidade (p<0,001) no CP contra CN, BP e VL dos extratos puros de cultivo, nos diferentes tempos de exposi??o (24, 48 e 72 horas). N?o houve diferen?a significativa da citotoxicidade do Grupo BP e VL contra CN. Houve diferen?a de citototoxicidade (p=0,01) quando extratos de 10% em cultura celular de 48 horas foram usados nos Grupos VL (17,4?1,4) e BP (14,5?0,6). Uma diferen?a tamb?m foi detectada na citotoxicidade (p=0,014) no Grupo BP em 48 horas de cultura, entre o extrato de 10% (14,5?0,6) contra os extratos de 60% (16,7?1,0) e 100% (17,0?1,3). O Grupo VL em cultura de 72 horas mostrou uma diferen?a na citotoxicidade (p=0,041) quando comparados os extratos de 60% (21,3?1,6) e 100% (17,5?2,1). A viabilidade celular dos extratos do Veloderm? e Biopiel? independente do tempo de exposi??o e concentra??o encontraram-se entre 75% e 100% na compara??o com CN. Segundo a classifica??o baseado na ISO 10993, ambos os extratos puros de EPH foram definidos n?o t?xicos (NT). Conclus?o: O conjunto dos resultados sugere alta biocompatibilidade dos EPHs testados; entretanto, o teste colorim?trico de MTT representa uma avalia??o inicial, sendo importante seu papel na racionaliza??o da experimenta??o in vivo e cl?nica dos biomateriais. Esta hip?tese precisa ser confirmada com testes complementares segundo normas da ISO 10993.

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38

Lei, Lei. "Étude des matériaux poreux thermo compressés pour la modélisation des écrans acoustiques automobiles." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2428/document.

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Ce travail a été réalisé dans le cadre du projet EcOBEx, qui consiste à réduire le bruit du groupe motopropulseur rayonné à l'extérieur par l'ajout d'écrans acoustiques dans le compartiment moteur du véhicule. Les écrans acoustiques sont fabriqués par thermocompression de matériaux poreux uniformes. Les propriétés et l'épaisseur du matériau évoluent en fonction du degré de compression subit par le matériau. L'objectif de ce travail est de proposer des lois pour prédire l'évolution des propriétés des matériaux à partir du taux de compression et de leurs valeurs initiales avant compression. Dans un premier temps, on s'intéresse aux paramètres du modèle de fluide équivalent de Johnson-Champoux-Allard-Lafarge (JCAL) : porosité, résistivité au passage d'air, tortuosité, longueurs caractéristiques visqueuse et thermique, perméabilité thermique statique. Des expressions analytiques sont proposées pour prédire la variation de ces paramètres en fonction de la compression. Elles sont développées à partir d'un modèle de matériaux fibreux à fibres cylindriques où les variations d'orientation des fibres induites par la thermocompression peuvent être prises en compte. Les résultats sont en bon accord avec les mesures effectuées sur deux types de matériaux (mousse à cellules ouvertes et fibreux). Un modèle empirique généralisé est finalement proposé pour la résistivité au passage d'air. Dans un deuxième temps, on s'attache aux paramètres élastiques dont la connaissance est essentielle pour prendre en compte la vibration du squelette. La méthode expérimentale quasistatique est d'abord appliquée pour étudier l'évolution du module de Young par rapport au taux de compression pour les fibres et les mousses. Une loi de puissance est alors proposée pour prédire ces variations. Enfin, une méthode inverse pour estimer les propriétés élastiques d'un matériau poroélastique orthotrope à partir d'une mesure vibratoire d'un écran tricouche thermo comprimé est proposée. Cette méthode permet de caractériser les propriétés élastiques du matériau poreux dans une situation proche de son application réelle
This work was carried out in the framework of the project EcOBEx, whose main objective was to reduce the passby noise by mean of acoustic shields in the engine compartment of the vehicle. The acoustic shields are manufactured by thermocompression of uniform porous materials. The material’s properties and thickness evolve according to the degree of compression experienced by the material. The objective of this work is to propose some laws to predict the evolution of the materials properties from their initial non compressed values and the compression rate. Firstly, we focus on the parameters of the Johnson-Champoux-Allard-Lafarge (JCAL) equivalent fluid model : porosity, air-flow resistivity, tortuosity, viscous characteristic lengths, thermal characteristic length, static thermal permeability. Some analytical expressions are proposed to predict the variation of these parameters as a function of compression. They are derived from a physical model of cylindrical fibres where the fibre orientation variations induced by the thermocompression can be taken into account. The results are in good agreement with the measurements made two types of materials (open cell foam and fibrous). A generalized empirical model is finally proposed for the air-flow resistivity.In a second part, we focus on the elastic parameters, which are necessary to take into account the vibration of the skeleton. The quasi-static experimental method is first applied to study the evolution of the Young’s modulus along the compression rate for fibrous and open cell foams. A power law is then proposed to predict these variations. Finally, an inverse method for estimating the elastic properties of an orthotropic poro-elastic material from a vibratory measurement of a thermocompressed three layer sandwich structure is proposed. This method allows us to characterize the elastic properties of a porous material in a situation close to its actual application

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39

Allen, Ryan B. "MATERIAL DIFFERENCES IN EQUINE CORTICAL AND TRABECULAR BONE." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1186.

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A greater understanding of bone materials would be beneficial in creating more accurate computer models and in the making of biomedical products involving bone. This study set out to determine whether cortical and trabecular bone are two separate materials, or whether they are the same material with a variance in porosity. To answer this question, samples were taken from different sections of the equine metacarpus, underwent densitometry analysis and were statistically analyzed. The majority of results suggest that the material is the same between varying densities of bone and thus the same between cortical and trabecular bone. These particular results are consistent with current standard practices. However, in several instances specifically regarding high porosity trabecular bone, a variance in density was found likely indicating a combination of differences in both material and architecture. Further studies should be done with specific focus on material variances to high porosity trabecular bone to improve the accuracy of computer models and general knowledge.

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Zeng, Lingli. "Contribution à l'étude du foudroyage en travaux miniers par modélisation physique en matériaux équivalents." Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL079N.

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Les travaux effectués concernent l'étude des phénomènes de rupture et de foudroyage des bancs du toit d'une couche minérale exploitée par longue taille, par une méthode de modélisation physique en matériaux équivalents. Celle-ci est non seulement intéressante par son aspect visuel et direct, mais permet également une étude quantitative par l'introduction des conditions de similitude. Apres étude des conditions de similitude et analyse dimensionnelle, deux séries de matériaux équivalents sont mis en œuvre. Ces matériaux, avec lesquels de nombreuses maquettes ont été réalisées, sont bien adaptés à la modélisation des roches. Les essais nous permettent d'observer différents phénomènes de formations, de rupture et de foudroyage du toit et d'identifier les fissures et leurs propagations dans les bancs du toit. A la suite des mesures et des observations pendant les essais, des modèles mécaniques (poutres à trois articulations) sont établis, qui expliquent l'état d'équilibre des bancs et les phénomènes observés en tenant compte de leur comportement post-rupture. Cela permet de mieux analyser et comprendre le mécanisme de rupture et de foudroyage. En complément, la réalisation d'un film vidéo et son scenario ont été décrits en détail. Le film explique la méthode utilisée et présente les essais effectués illustrant les phénomènes de rupture et de foudroyage.

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Gnoli, Daniel. "Studio di profili tubolari in FRP: omogeneizzazione e modello trave equivalente." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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Il seguente elaborato di tesi nasce con lo scopo di valorizzare l’utilizzo di tubi cavi in materiale composito, principalmente in ambito offshore, poiché caratterizzati da un’elevata efficienza strutturale e soprattutto da un eccellente resistenza alla corrosione. In merito a questo, si fornisce un metodo alternativo atto a velocizzare e permettere la progettazione di essi senza l’utilizzo di un laborioso modello 3D agli elementi finiti. Lo studio effettuato, oltre ad ampliare la conoscenza sul comportamento dei tubolari, consiste nel calcolare i coefficienti della matrice di rigidezza tramite una semplice formulazione analitica. Quest’ultima, valida per la maggior parte degli schemi di laminazione, sfrutta il metodo di omogeneizzazione della sezione di Sun et al. e la formulazione di Eulero-Bernoulli per ottenere i coefficienti di rigidezza di un materiale isotropo. Si è constatato come attraverso il modello equivalente beam-frame 3D conseguito sia possibile ottenere valori dei coefficienti della matrice di rigidezza con errori minori del 5% rispetto a quelli definiti tramite il modello shell 3D agli elementi finiti. Per lo studio affrontato si sono considerati i laminati Cross-Ply, Angle-Ply, bilanciati e non, e laminati con configurazione particolare, ovvero, laminati con variazione angolare delle fibre tra gli strati molto piccola e laminati con materiali compositi fortemente ortotropi tali da generare valori di poisson negativi o molto elevati a seconda dello schema di laminazione. Si è cercato, infine, di dare una visione più concreta dell’argomento trattato illustrando un impiego plausibile, ovvero quello del ponteggio in ambito offshore. Grazie alla Gruppo Cosmi S.p.a. e alla Seico compositi S.r.l. è stato possibile effettuare un confronto a livello economico e gestionale tra i "tubi innocenti" tradizionali in acciaio e quelli in materiale composito valorizzando l’utilizzo di quest’ultimi.

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Córdova, Pérez Claudia Cecilia, Soto Liseth Adriana Cuéllar, and Barrios Mayra Shuguey Guizado. "Comparación de la resistencia equivalente a la flexión entre las fibras de acero Wirand producidas en Italia y las producidas en Perú." Bachelor's thesis, Pontificia Universidad Católica del Perú, 2012. http://tesis.pucp.edu.pe/repositorio/handle/123456789/1612.

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En el presente trabajo se busca obtener el valor Re3, para 3 dosificaciones de concreto (210, 245 y 280 kg/cm2) por dosificación de fibra (20 y 25kg/m3) para cada tipo de fibra Wirand FF1 Y FF3.
Tesis

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Hösthagen, Anders. "Thermal Crack Risk Estimation and Material Properties of Young Concrete." Licentiate thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65495.

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This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. If the stress reaches the tensile strength of the young concrete, one or several cracks will occur. The main focus of this work is how to establish a theoretical model denoted Equivalent Restraint Method model, ERM, and the correlation between ERM models and empirical experiences. A key factor in these kind of calculations is how to model the restraint from any adjacent construction part or adjoining restraining block of any type. The building of a road tunnel and a railway tunnel has been studied to collect temperature measurements and crack patterns from the first object, and temperature and thermal dilation measurements from the second object, respectively. These measurements and observed cracks were compared to the theoretical calculations to determine the level of agreement between empirical and theoretical results. Furthermore, this work describes how to obtain a set of fully tested material parameters at CompLAB (test laboratory at Luleå University of Technology, LTU) suitable to be incorporated into the calculation software used. It is of great importance that the obtained material parameters describe the thermal and mechanical properties of the young concrete accurately, in order to perform reliable crack risk calculations. Therefore, analysis was performed that show how a variation in the evaluated laboratory tests will affect the obtained parameters and what effects it has on calculated thermal stresses.

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Díaz, Escriche Enrique. "Simulación y control de los procesos de transferencia de resina en moldes flexibles mediante modelos de permeabilidad equivalente." Doctoral thesis, Universitat Politècnica de València, 2012. http://hdl.handle.net/10251/17321.

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El objetivo de la presente tesis es el desarrollo de una metodología original para el diseño óptimo de los procesos de transferencia de resina con ayuda de vacío en la fabricación de materiales compuestos de matriz polimérica. Se trata de un sistema experto que permite reducir el esfuerzo necesario para la optimización del proceso de fabricación y la eliminación de una estrategia basada en el ensayo y error en favor del prototipado virtual en el diseño de los utillajes necesarios. Para la puesta en marcha y validación del sistema experto se han desarrollado las siguientes aportaciones originales: 1. Se ha desarrollado y puesto en marcha un dispositivo experimental original para la caracterización de la permeabilidad flexible de preformas con el ánimo de desarrollar una estrategia de simulación rápida, con reducido esfuerzo computacional y limitada necesidad de determinación experimental de las características del refuerzo (permeabilidad) que permita el diseño preliminar de moldes de infusión con garantía de llenado de la cavidad y tiempos de ciclo reducidos. 2. Se ha puesto en marcha el banco de permeabilidad flexible con una serie de refuerzos típicamente utilizados en la tecnología de materiales compuestos, tales como mats de fibras continuas, tejidos multidireccionales, tejidos híbridos con núcleo para facilitar el paso de la resina y tejidos realizados con fibras de origen natural. Se estudia además en el presente trabajo cómo influyen los radios de curvatura del molde sobre elementos tales como núcleos en el flujo de la resina. 3. Se ha investigado también en el presente trabajo cómo monitorizar la posición del frente de flujo de resina y el grado de curado de la misma con el tiempo. Se han probado con éxito los sensores denominados de flujo de calor en dispositivos de infusión, que permiten registrar la transferencia de energía debida, por un lado, a la diferencia de temperatura entre la resina y el molde a su paso por el sensor y, por otro, a la reacción de p
Díaz Escriche, E. (2012). Simulación y control de los procesos de transferencia de resina en moldes flexibles mediante modelos de permeabilidad equivalente [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17321
Palancia

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Walker, Scottie. "Spectrally-matched neutron detectors designed using computational adjoint S_{N for plug-in replacement of Helium-3}." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49093.

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Neutron radiation detectors are an integral part of the Department of Homeland Security (DHS) efforts to detect the illicit trafficking of radioactive or special nuclear materials into the U.S. In the past decade, the DHS has deployed a vast network of radiation detection systems at various key positions to prevent or to minimize the risk associated with the malevolent use of these materials. The greatest portion of this detection burden has been borne by systems equipped with 3He because of its highly desirable physical and nuclear properties. However, a dramatic increase in demand and dwindling supply, combined with a lack of oversight for the existing 3He stockpile has produced a critical shortage of this gas which has virtually eliminated its viability for detector applications. A number of research efforts have been undertaken to develop suitable 3He replacements; however, these studies have been solely targeted toward simple detection cases where the overall detection efficiency is the only concern. For these cases, an insertion of additional detectors or materials can produce reaction rates that are sufficient, because the neutron spectral response is essentially irrelevant. However, in applications such as safeguards, non-proliferation efforts, and material control and accountability programs (MC&A), a failure to use detectors that are spectrally matched to 3He can potentially produce dire consequences. This is because these more difficult detection scenarios are associated with fissile material assessments for 239Pu and other actinides and these analyses have almost universally been calibrated to an equivalent 3He response. In these instances, a “simple” detector or material addition approach is neither appropriate nor possible, due to influences resulting from the complex nature of neutron scattering in moderators, cross sections, gas pressure variations, geometries, and surrounding structural interference. These more challenging detection cases require a detailed computational transport analysis be performed for each specific application. A leveraged approach using adjoint transport computations that are validated by forward transport and Monte Carlo computations and laboratory measurements can address these more complex detection cases and this methodology was utilized in the execution of the research. The initial task was to establish the fidelity of a computational approach by executing radiation transport models for existing BF3 and 3He tubes and then comparing the modeling results to laboratory measurements made using these identical devices. Both tubes were 19.6 cm in height, 1-inch in diameter, and operated at 1 and 4 atm pressure respectively. The models were processed using a combination of forward Monte Carlo and forward and adjoint 3-D discrete ordinates (SN) transport methods. The computer codes MCNP5 and PENTRAN were used for all calculations of a nickel-shielded plutonium-beryllium (PuBe) source term that provided a neutron output spectra equivalent to that of weapons-grade plutonium (WGPu). Once the computational design approach was validated, the adjoint SN method was used to iteratively identify six distinct plug-in models that matched the neutron spectral response and reaction rate of a 1-inch diameter 3He tube with a length of 10 cm and operating at 4 atm pressure. The equivalent designs consist of large singular tubes and dual tubes containing BF3 gas, 10B linings, and/or 10B-loaded polyvinyl toluene (PVT). The reaction rate for each plug-in design was also verified using forward PENTRAN and MCNP5 calculations. In addition to the equivalent designs, the adjoint method also yielded various insights into neutron detector design that can lead to additional designs using a combination of different detector materials such as BF3/10B-loaded PVT, 10B-lined tubes/10B-loaded PVT, etc.

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Gutiérrez, Meana Javier. "Evaluación de niveles de campo electromagnético en entornos rurales/urbanos mediante técnicas de procesado geométrico y método MECA (Modified Equivalent Current Approximation)." Doctoral thesis, Universidad de Oviedo, 2010. http://hdl.handle.net/10803/11143.

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En esta Tesis Doctoral se presenta el método determinístico de alta frecuencia denominado Modi_ed Equivalent Current Approximation (MECA). Su ámbito de aplicación se circunscribe al cálculo de niveles de campo electromagnético a partir de unas corrientes equivalentes, tanto eléctricas como magnéticas, para un escenario eléctricamente grande. Se trata de una extensión de la formulación clásica de Óptica Física para la consideración no solo de super_cies de tipo conductor eléctrico perfecto sino también dieléctrico o con pérdidas.El método MECA debe ser complementado por un algoritmo de cálculo de visibilidades para distinguir entre zonas iluminadas y en sombra desde un punto de vista. En consonancia con ello se evalúan cuatro distintas metodologías, de las cuales tres son nuevas (Método Cono, Método Pirámide y Método Recorte) y la restante, Binary Space Partitioning, se emplea como referencia.La validación se efectúa a partir del cómputo de la sección recta radar de diversas geometrías canónicas y se contrasta con sus expresiones analíticas o bien con los resultados provistos por la técnica de onda completa basada en el Método de los Momentos. Adicionalmente se contemplan diferentes aspectos de interés ligados a MECA, como el efecto de la polarización o el ángulo de incidencia.La inclusión de métodos de aceleración basados en división en dominios o limitación en alcance y la descripción de la herramienta de cálculo de cobertura radioeléctrica desarrollada dan paso a los ejemplos de aplicación. Estos consisten en una optimización de una red GSM/GPRS en un entorno rural y una diagnosis en un entorno urbano con dos estaciones transmisoras de radio. También se muestra un escenario para evaluar el comportamiento en interiores.

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Soulas, Floriane. "Développement d'un modèle mécanique pour la prédiction des dommages de panneaux composites aéronautiques soumis à un choc foudre." Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0004/document.

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Dans un contexte industriel où l’utilisation de matériaux composites s’est généralisée jusqu’à atteindre les structures primaires, la menace foudre se révèle être une problématique majeure.Avec un coup de foudre en moyenne par an et par avion en service, les nouvelles structures composites, moins bonnes conductrices que leurs prédécesseurs en métal, doivent être protégées. Les protections mises en œuvre par les fabricants et les équipementiers sont des couches minces ajoutées à l’empilement composite, initialement choisi pour le compromis optimal qu’il offre entre résistance et légèreté. L’optimisation et le conseil concernant les protections foudre deviennent alors un enjeu industriel d’importance. Dans ce cadre, le travail de thèse a porté sur l’étude et la compréhension des dommages issus des chocs foudre sur des structures protégées dans le but ultérieur d’optimiser ou de créer des protections adaptées.Nous proposons une méthode qui permet de déterminer les caractéristiques d’un impact mécanique sur une plaque composite nue, équivalent à un choc foudre sur une structure protégée. Une campagne d’essais d’impacts avec un canon du laboratoire couplé à une campagne numérique ont permis de conclure que la stratégie et la méthode d’équivalence sont fondées, et permettent de prendre en compte les paramètres constitutifs de la protection de surface. Les modèles proposés permettront d’aborder les questions de conception des protections
In an industrial context where more and more composite materials are integrated into primary structures, the lightning threat has become a major issue for aircraft manufacturers. As lightning strikes in service airplane about once a year, the new composite structures, with a lower electrical conductivity than their metallic predecessors, must be protected. The protections already integrated by manufacturers are mainly made of expanded metallic foil layered above the composite lay-up, thus adding weight on the low density structures and reducing the gain of weight. The optimization of such structures and counsel concerning lightning protection become a major industrial stake. In the scope of the PhD work, the proposed work focused on the study of the damage mechanisms due to lightning strikes on protected composite panels in order to optimize or offer adequate protections against this threat. A methodology is proposed to determine a mechanical impact on a bare composite plate equivalent to a protected and even painted structure submitted to a lightning impact. An experimental campaign of mechanical impacts using a canon gas gun coupled to a numerical plan is led and allows concluding on the strategy and its validity by taking into account the state surface of the lightning samples

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Giljum, Stefan, Hanspeter Wieland, Franz Stephan Lutter, Nina Eisenmenger, Heinz Schandl, and Anne Owen. "The impacts of data deviations between MRIO models on material footprints: A comparison of EXIOBASE, Eora, and ICIO." Wiley, 2019. http://dx.doi.org/10.1111/jiec.12833.

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In various international policy processes such as the UN Sustainable Development Goals, an urgent demand for robust consumption-based indicators of material flows, or material footprints (MFs), has emerged over the past years. Yet, MFs for national economies diverge when calculated with different Global Multiregional Input-Output (GMRIO) databases, constituting a significant barrier to a broad policy uptake of these indicators. The objective of this paper is to quantify the impact of data deviations between GMRIO databases on the resulting MF. We use two methods, structural decomposition analysis and structural production layer decomposition, and apply them for a pairwise assessment of three GMRIO databases, EXIOBASE, Eora, and the OECD Inter-Country Input-Output (ICIO) database, using an identical set of material extensions. Although all three GMRIO databases accord for the directionality of footprint results, that is, whether a countries' final demand depends on net imports of raw materials from abroad or is a net exporter, they sometimes show significant differences in level and composition of material flows. Decomposing the effects from the Leontief matrices (economic structures), we observe that a few sectors at the very first stages of the supply chain, that is, raw material extraction and basic processing, explain 60% of the total deviations stemming from the technology matrices. We conclude that further development of methods to align results from GMRIOs, in particular for material-intensive sectors and supply chains, should be an important research priority. This will be vital to strengthen the uptake of demand-based material flow indicators in the resource policy context.

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Santos, Antonio Carlos Godinho dos. "Equivalência de estímulos e aquisição do conceito de proporção: efeito de instruções programadas, manipulação de material concreto e treino de composição." Pontifícia Universidade Católica de Goiás, 2010. http://localhost:8080/tede/handle/tede/1775.

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Made available in DSpace on 2016-07-27T14:18:43Z (GMT). No. of bitstreams: 1 Antonio Carlos Godinho dos Santos.pdf: 1568718 bytes, checksum: c84bef3972697df980163958f88b2a62 (MD5) Previous issue date: 2010-12-17
Literature points that children in sixth grade of Middle School show difficulty to solve fractional problems that demand the concept of proportion. Behavior analysis affords efficient techniques and procedures to form stimulus classes that originate concepts. Nevertheless, few production about concepts formation based on this perspective were achieved on Math field. The present study s goal is to investigate the effect of conditional relationship training between: fractional pictorial stimulus (group A) and numerical (group B) and, numerical (group B) and numerical (group C), both performed by means of the stimulus equivalence paradigm, concerning formation of equivalence classes with fractional stimulus, generalization of responses to new situations and the expansion of the formed classes after the training among members of group A and a new group of numerical stimulus (D). Three experiments were conducted with an amount of 90 children enrolled in State educational system in Goiania and Trindade cities, falling into both genres whose ages range from 11 to 14 years old. The participants, divided in experimental and control groups, were initially submitted to a pencil and paper evaluation about fractional problems (IE) expressed in absolute and relative way. In the first experiment, one group was exposed only to the training with programmed instructions about fractional problem resolutions (PIG), another one only to conditional relationship training (EQG) and a third one to both trainings (EQPIG). In experiment 2, one group handled concrete material presented in form of fraction (CMG), another one went through the training of the two conditions (CMGEQ). In experiment 3, one group trained conditional relationships with fractional stimulus (EQG), another one went through the training of compounding (copying) fractions from models visually presented and conditional relationship tests (EQCTG) and to a third group was asked the exposition of the strategies adopted to solve problems during the trainings and conditional relationship tests (GEQR). At the end of the procedures all of them went through a final evaluation (FE) identical to the initial evaluation (IE). The control participants took only the initial and final evaluations. The results show that participants presented difficulty to solve problems expressed in relative way. Generally, all the participants of the experimental groups of the three experiments formed three fractional stimulus classes (ABC), however there was no expansion of these classes after the training between one of its members and a new stimulus. The highest generalization indexes occurred in the first programmed test and decreased in the second evaluation. Only participants of experimental groups presented systematic gains from IE to FE, considering that the highest performances to problems with fractions occurred to participants in EQPIG group.
A literatura aponta que crianças de final do sexto ano do ensino fundamental demonstram dificuldade para resolver problemas fracionários que exigem o conceito de proporção. A análise do comportamento dispõe de técnicas e procedimentos eficientes para formar classes de estímulos que dão origem a conceitos. Contudo, poucos trabalhos sobre formação de conceitos embasados nessa perspectiva foram realizados no campo da matemática. O objetivo do presente estudo foi investigar o efeito do treino de relações condicionais entre: estímulos fracionários pictóricos (conjunto A) e numéricos (conjunto B) e, entre estímulos fracionários numéricos (conjunto B) e numéricos (conjunto C), ambos realizados por meio do procedimento de pareamento com o modelo a partir do paradigma de equivalência de estímulos sobre a formação de classes de equivalência com estímulos fracionários, tendo sido avaliada também a generalização da resposta a novas situações e a expansão das classes formadas após o treino entre os membros do conjunto A e um novo conjunto de estímulos numéricos (D). Foram conduzidos três experimentos com um total de 90 crianças matriculadas na rede estadual de ensino das cidades de Goiânia e Trindade, de ambos os sexos cujas idades variaram entre 11 e 14 anos. Os participantes, divididos em grupos experimentais e de controle, passaram inicialmente por uma avaliação do tipo lápis e papel sobre problemas fracionários (AI) expressos de forma absoluta e relativa. No primeiro experimento, um grupo foi exposto apenas ao treino com instruções programadas sobre a resolução de problemas fracionários (GIP), outro apenas ao treino de relações condicionais (GEQ) e um terceiro a ambos os treinos (GIPEQ). No experimento 2, um grupo manuseou material concreto apresentado em forma de fração (GMC), outro fez treino de relações condicionais entre estímulos fracionários (GEQ) e um terceiro passou pelo treino das duas condições (GMCEQ). No experimento 3, um grupo fez treino de relações condicionais com estímulos fracionários (GEQ), outro passou pelo treino de composição (cópia) de frações a partir de modelos apresentados visualmente mais o treino de relações condicionais (GEQTC) e a um terceiro grupo foi solicitado o relato das estratégias que eles adotaram para resolver os problemas durante os treinos e testes das relações condicionais(GEQR). Ao final dos procedimentos todos eles passaram por uma avaliação final (AF) idêntica à avaliação inicial (AI) aplicada no início do estudo. Os participantes controles fizeram apenas as avaliações inicial e final. Os resultados mostraram que os participantes demonstraram dificuldade para resolver problemas expressos na forma relativa. Em geral, todos os participantes dos grupos experimentais dos três experimentos formaram três classes de estímulos fracionários (ABC), mas não houve expansão dessas classes após o treino entre um de seus membros e um novo estímulo. Os maiores índices de generalização ocorreram no primeiro teste programado e decaíram na segunda avaliação. Apenas os participantes dos grupos experimentais apresentaram ganhos sistemáticos da AI para a AF, sendo que as maiores porcentagens de acertos para problemas com frações expressas de forma relativa ocorreram para os participantes do grupo GIPEQ.

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Aydincak, Ilke. "Investigation Of Design And Analyses Principles Of Honeycomb Structures." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608998/index.pdf.

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In this thesis, design and analyses of honeycomb structures are investigated. Primary goal is to develop an equivalent orthotropic material model that is a good substitute for the actual honeycomb core. By replacing the actual honeycomb structure with the orthotropic model, during the finite element analyses, substantial advantages can be obtained with regard to ease of modeling and model modification, solution time and hardware resources . To figure out the best equivalent model among the approximate analytical models that can be found in the literature, a comparison is made. First sandwich beams with four different honeycomb cores are modeled in detail and these are accepted as reference models. Then a set of equivalent models with the same dimensions is generated. The material properties of the equivalent models are taken from different studies performed in the literature. Both models are analyzed under the same loading and the boundary conditions. In finite element analyses, ANSYS finite element program is used. The results are compared to find out the best performing equivalent model. After three major analyses loops, decision on the equivalent model is made. The differences between the total reaction forces calculated by the equivalent model and the actual honeycomb model are all found to be within 10%. The equivalent model gives stress results at the macro-scale, and the local stresses and the strains can not be determined. Therefore it is deemed that for stress analysis, equivalent model can be used during the preliminary design phase. However, the equivalent model can be used reliably for deflection analysis, modal analysis, stiffness determination and aero-elastic analysis.

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Dissertations / Theses on the topic 'Equivalent materials'

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