[pt] O estudo teve por objetivo investigar o mecanismo de formação de trincas superficiais na direção longitudinal de laminação em barras do aço 1538 DH adotado na fabricação de componentes para a indústria automobilística. Tem-se conseguido alguns avanços no entendimento dos mecanismos de trincamento de produtos laminados, porém tais avanços não permitem, até o presente momento, a eliminação total do problema, o que vem causando o sucateamento de um expressivo percentual de produtos siderúrgicos. No escopo deste trabalho chegou-se a características microestruturais do material que sugerem as causas do trincamento durante o processo de laminação e, para tal, realizou-se o mapeamento das trincas, análises por microscopia ótica, classificação das inclusões, caracterizações por microscopia eletrônica de varredura e EDS, difração de raios-X, ensaios de tração, ensaios de dureza e microdureza, bem como simulação de ciclos térmicos. Os resultados destas análises indicaram que a nucleação e posterior propagação das trincas podem estar relacionadas à presença de precipitados de segunda fase em regiões interdendríticas, o que causaria a fragilização do contorno de grão durante laminação a quente. / [en] The purpose of this study was to investigate the cracking mechanism with regard to longitudinal surface cracks in rolled 1538 DH steel bars used for the automotive industry. Although some advances have been achieved concerning the understanding of the cracking mechanism, the problem is not yet totally eliminated and still causing the scraping of a significant percentage of steel products. In the course of this work it was possible to determine some microstructural characteristics of the material which may lead to cracking due to the rolling process. In this sense, it was necessary to carry out an experimental procedure that included crack mapping, optical microscopy, classification of the inclusions, scanning electron microscopy, EDS analysis, X- ray diffraction, tensile testing, hardness and microhardness evaluation as well as thermal cycle simulations. The results seem to suggest that the crack nucleation and crack propagation are related to the presence of interdendritic second phase particles which induce to grain boundary embrittlement during hot rolling.

O presente trabalho consiste no aprimoramento de formulação do Método dos Elementos Finitos (MEF) para barra geral laminada tridimensional pela consideração da cinemática de empenamento para seção qualquer. Desenvolve-se um código computacional para se solucionar o empenamento, considerando-se uma derivada do giro em relação ao eixo longitudinal de valor unitário, do problema de torção livre de Saint-Venant para uma seção transversal de geometria qualquer, homogênea e não-homogênea. Posteriormente o código desenvolvido é adaptado de forma a ser acoplado a um programa com formulação de barra geral tridimensional laminada, que segue a cinemática de Reissner-Timoshenko generalizada, enriquecendo-o com a consideração do empenamento. A primeira contribuição significativa do desenvolvimento do trabalho é a inclusão de geometrias quaisquer para a seção transversal, possibilitando, por exemplo, a consideração de núcleos estruturais mistos em edifícios, abertos e fechados por trechos. A segunda contribuição é referente à consideração de material laminado, possibilitando considerar núcleos estruturais de materiais compostos. Exemplos gerais são resolvidos para a verificação e validação da formulação proposta e implementada. / In the present work an improved finite element formulation for the analysis of three-dimensional laminated bars is presented. The improvement is made by introducing the warping mode into the previous model that follows a general Reissner-Timoshenko kinematics hypotesis. In order to do so, a two-dimensional code is developed, based on Saint Venant\'s torsion problem; to find the warping mode for any considered cross-section, including non-homogeneous material. Each warping mode is achieved for unitary rotation by unit of length. This warping mode is weighted by a new parameter, the intensity of warping, and then added to the Reissner-Timoshenko kinematics, resulting into the enhanced formulation. The existent computational code is modified accordingly to this new kinematics and tested regarding its capacity of reproducing analytical results for Saint-Venant torsion and Vlasov bending-torsion theories. Some results for laminated cross sections are also provided. It is worth stressing that the main contributions of this work are two. The first is the consideration of warping for general 3D bars with any cross section, i.e., not limited to thin-walled cross sections. The second is the consideration of laminated materials for any cross section.

A tendÃncia de consumo de alimentos saudÃveis, inovadores e prÃticos tem levado ao crescimento cada vez maior nos Ãltimos anos do mercado de barras de cereais. As barras de cereais sÃo formadas por grÃos de cereais processados e aglomerados, e a elas podem ser incorporados diferentes ingredientes, tais como cereais integrais, frutas desidratadas ou cristalizadas, amÃndoas e aÃÃcares. Existem na flora nativa brasileira, algumas espÃcies ainda pouco conhecidas, mas que apresentam potencialidades para o mercado de amÃndoas, como o chichÃ, sapucaia e castanha-do-gurguÃia. No entanto, observa-se tambÃm a importÃncia da utilizaÃÃo dos resÃduos gerados do processamento das frutas, como cascas, talos e bagaÃos, podem esses ser aproveitados na dieta humana. Assim, objetivou-se neste trabalho desenvolver barras de cereais a partir de amÃndoas de chichÃ, sapucaia e castanha-do-gurguÃia, complementadas com casca de abacaxi. Foram formuladas barras de cereais com trÃs formulaÃÃes (A, B e C), as quais se diferenciavam pela quantidade adicionada de gordura vegetal hidrogenada e pà da casca de abacaxi. Posteriormente, foram elaborados nove tipos de barras de cereais, sendo trÃs com amÃndoas de chichÃ, trÃs com amÃndoas de castanha-do-gurguÃia e trÃs com amÃndoas de sapucaia, as quais foram avaliadas microbiologicamente e sensorialmente. ApÃs a avaliaÃÃo sensorial, escolheram-se as barras de cereais com maiores notas de impressÃo global, sendo essas submetidas a anÃlises quÃmicas. A sapucaia destacou-se, dentre as amÃndoas avaliadas, por apresentar as maiores mÃdias para a maioria dos parÃmetros avaliados. Verificou-se atravÃs do parÃmetro impressÃo global que dentre as formulaÃÃes testadas a que exibiu a maior nota de aceitaÃÃo foi a formulaÃÃo B, entre as barras de cereais com as trÃs amÃndoas estudadas. As barras de cereais elaboradas com amÃndoas de chichà e sapucaia de um modo geral foram mais aceitas do que as barras de cereais com amÃndoas de castanha-do-gurguÃia. No que se referem aos minerais, os de maior teor nas barras de cereais elaboradas neste estudo, foram, respectivamente, o potÃssio, sÃdio, ferro e zinco. Conclui-se ser viÃvel a utilizaÃÃo das amÃndoas de chichÃ, sapucaia e castanha-do-gurguÃia, e do pà da casca de abacaxi na elaboraÃÃo de barras de cereais. / The trend of consumption of healthy food, innovative and practical has led to growth increasing in recent years the market for the cereal bars. The cereal bars are formed by grain cereals, processed and clusters, and they can be incorporated different ingredients, such as integral cereals, dehydrated fruit or crystallized fruit, almonds and sugars. There are in the native Brazilian flora, some species still little known, but which have potential for the market of almonds, as chichÃ, sapucaia and chestnut-of-gurguÃia. However, its observe also the importance of the use of waste generated from fruit processing, such as bark, stems and cake, these can be used in the human diet. Thus, the objective of this work was to develop the cereal bars from almonds to chichÃ, sapucaia and chestnut-of-gurguÃia, supplemented with pineapple bark. Cereal bars were making with three formulations (A, B and C), which they were different by the amount added of hydrogenated vegetable fat and dust of the pineapple bark. Subsequently, nine types of the cereal bars were prepared, three with almonds, chichÃ, three with almonds, chestnut-do-gurguÃia and three of sapucaia with almonds, which were evaluated microbiologically and sensorial. After the sensory evaluation, the cereal bars with higher notes of overall impression was chose, and those subjected to chemical analyses. The sapucaia highlighted is among the almonds evaluated, by presenting the greatest medium for most parameters evaluated. It was found by the parameter overall impression that among the formulations tested showed that the largest note of acceptance was the formulation B, between the cereal bars with the three almonds studied. The cereal bars, developed with almonds of chichà and sapucaia, in general, were more accepted than cereal bars with almonds of chestnut-do-gurguÃia. With regard to minerals, the highest levels in the cereal bars prepared in this study were, respectively, potassium, sodium, iron and zinc. It is viable to use the almonds, chichÃ, sapucaia and chestnut-of-gurguÃia, and the dust of the pineapple bark in the preparation of the cereal bars.

O amaranto é um pseudocereal de grande valor nutricional que apresenta quantidade de fibras e proteína superior aos cereais usualmente consumidos. Características como o aproveitamento integral da planta e a sua capacidade de adaptação ao solo despertaram o interesse dos pesquisadores em cultivá-lo no Brasil. Objetivo: Desenvolver um processo para obtenção de cereais matinais e barras de cereal à base de amaranto visando a máxima aceitação e mínima perda de nutrientes. Metodologia: O cereal matinal foi produzido em extrusora de rosca única com capacidade de produção semi-industrial e as barras de cereal de acordo com técnica dietética apropriada. A modelagem da produção dos cereais matinais foi realizada empregando-se a metodologia de superfície de resposta, as variáveis dependentes (resposta) escolhidas foram razão de expansão máxima (RE) e força de cisalhamento mínima (FC), as variáveis independentes foram umidade da amostra e temperatura da terceira zona de aquecimento da extrusora. Resultados: Após dois delineamentos compostos centrais verificou-se que a umidade da amostra não exerceu efeito significativo no produto final, dessa forma a variável independente de importância para o estudo foi a temperatura do processamento. O ponto ótimo para o cereal matinal desenvolvido com a farinha desengordurada foi 15% de umidade e 140º C na terceira zona de aquecimento. Foi elaborado um segundo cereal matinal com o grão integral e esse apresentou as mesmas características de expansão e textura do cereal com farinha desengordurada. Os provadores preferiram a amostra com farinha desengordurada, que obteve 72% de notas acima do ponto de corte pré-estabelecido (nota 7). Foram confeccionados dois tipos de barra de cereais, ambas com 70% de amaranto, uma apenas com amaranto estourado e outra com uma mistura de amaranto estourado e extrusado. O teor de fibra e proteína nas duas preparações foi superior ao de produtos similares sem amaranto. A barra de cereal somente com amaranto estourado foi preferida por 66% dos provadores, sendo que 77% atribuíram à mesma, notas superiores à de corte. Conclusão: A composição nutricional dos produtos desenvolvidos é superior aos similares confeccionados com outros cereais e ambos apresentaram alta aceitabilidade. / Amaranth is a pseudocereal of great nutritional value that exhibits amounts of fiber and protein higher than the usually consumed cereals. The agronomic characteristics and the possibility of utilization of the entire plant drew sufficient interest among plant breeders to produce this grain in Brazil. Objective: To develop amaranth-based breakfast cereals and cereal bars aimed at the maximal acceptance and minimal loss of nutrients. Methodology: The breakfast cereal was produced in a single screw extruder with semi-industrial capacity and the cereal bars in accordance with appropriate dietary technique. Results: After two central composite designs, it became evident that the independent variable of importance for the study was the temperature. It was observed that the moisture of the sample did not exert any significant effect in the final product within the range studied. Best results were obtained with 15% moisture and 140º C at the third zone. A breakfast cereal developed with the whole grain exhibited the same characteristics of expansion and texture of a product manufactured with the defatted flour. The sensory panel preferred the sample prepared with defatted flour, which obtained 72% of the grades above the pre-established cutting point 7. Two types of cereal bars, both containing 70% of amaranth, one with popped amaranth and another with a mixture of popped and extruded amaranth. The amount of protein and fiber was higher in these products when compared with similar formulations without amaranth. Cereal bars containing only the popped amaranth were preferred by 66% of the panel of whom 77% assigned grades equal to or higher than the cutting point. Conclusion: The nutritional value of the developed products is superior to the similars confectioned with other cereals and they had high acceptability.

Emendas por traspasse são criadas pela justaposição de barras de aço em um determinado comprimento, assegurando que elas se manterão em posição. Assim como em outros sistemas estruturais, a alvenaria estrutural de blocos de concreto utiliza barras de aço como reforço dos elementos quanto à resistência à tração, mais proeminentes em edifícios altos devido à ação dos ventos. As armaduras são projetadas para serem alocados no interior dos blocos, e a prática construtiva no Brasil é posicionar as armaduras de aço antes dos blocos serem assentados. Devido à essa prática, as paredes precisam ser construídas em pelo menos duas etapas, para considerar a altura limite imposta pela armadura posicionada ao operário na elevação dos blocos. Para aumentar a eficiência na elevação das paredes de alvenaria, hélices circulares são propostas como componentes de confinamento do graute que envolve a emenda, permitindo a elevação da parede em etapa única. A armadura é colocada dentro da seção transversal da espiral após a parede de alvenaria ser completamente elevada. O objetivo desta investigação é avaliar a eficiência da emenda por traspasse, com hélice circular atuando como componente do confinamento do graute que envolve a emenda. Quatro configurações de emenda distintas foram ensaiadas: a primeira, referência, foi justaposta e amarrada com arame; a segunda foi espaçada, porém sem a presença de um componente de confinamento; a terceira foi espaçada e continha uma hélice circular com passo de 3,5 cm; e a quarta foi espaçada e continha uma hélice circular com passo de 8,0 cm. Os ensaios permitiram concluir que a hélice de traspasse é um componente eficiente no confinamento das emendas por traspasse em alvenaria estrutural de blocos de concreto. Análises estatísticas dos resultados demonstram que emendas por a emenda com hélice circular de 3,5 cm não só é equivalente à emenda por referência do ponto de vista da resistência à tração, como também contribui para a redução de fissuras. / Lap slices are created by the overlapping of reinforcement bars over a specified length and reassuring that they stay in place. As with other structural systems, concrete block masonry uses reinforcing steel to carry the tensile loads which are more prominent on tall buildings due to the effect of wind. Reinforcing bars are designed to be placed inside block cells. The construction practice in Brazil is to place the reinforcing steel before the block units are laid. With this practice, walls need to be built in at least two lifts to account for the height limits imposed by the mason having to lift each block over the reinforcing bars. To increase the efficiency of wall construction, spirals are proposed as confinement components of the grout surrounding the lap splices, allowing a single-lift wall construction. The vertical reinforcement is then placed inside the cross-section of the spiral after the laying of blocks is complete. The objective of this investigation is to evaluate the efficiency of lap splices with spirals as confinement components of grout. Four types of single-bar splice specimens were prepared during the test program consisting of: first, contact lap splices tied by steel lock wires; second, non-contact lap splices without any confinement components; third, non-contact lap splices with the surrounding grout confined by spirals with 35 mm pitch; fourth, non-contact lap splices with the surrounding grout confined by spirals with 80 mm pitch. The results of the experimental program show that spirals are efficient confinement components of non-contact lap splices in concrete block masonry. Statistical analysis of results demonstrate that non-contact lap splices confined by spirals with 35 mm pitch are not only equivalent with contact lap splices regarding their ultimate tensile resistance, but also contribute to the reduction of cracks.

Orientador: Mário Roberto Maróstica Júnior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T20:29:29Z (GMT). No. of bitstreams: 1 Carvalho_GabrielaGuimaraes_M.pdf: 1142498 bytes, checksum: 1f84ae381c7847ae94ff63d8598e18d5 (MD5) Previous issue date: 2013 / Resumo: As barras de cereais são fonte de nutrientes, de fácil consumo e não necessitam de preparo pelo consumidor. O seu consumo tem crescido ultimamente. Elas apresentam composição variada, são constituídas por diversos cereais, e podem ser adicionadas de ingredientes como frutas, castanhas, chocolate e outros. O uso de edulcorantes também vem crescendo, devido ao grande número de pessoas diabéticas, ou que fazem seu uso para o controle de peso. Além disso, alguns ingredientes das barras de cereais (frutas, castanhas) apresentam atividade antioxidante importante, combatendo os radicais livres, de forma a evitar o desequilíbrio no estado de óxido-redução ou estresse oxidativo das células do organismo. A casca da jabuticaba (Myrciaria jaboticaba (Vell) Berg.) é rica em compostos fenólicos e antocianinas, proporcionando um aporte em compostos bioativos com função antioxidante expressiva. O objetivo deste trabalho foi formular barras de cereais com sacarose e edulcorantes (stévia e sucralose) adicionadas de diferentes concentrações de casca de jabuticaba, avaliando sua atividade antioxidante e a aceitação por meio de teste sensorial.Foi preparada a formulação da barra de cereal 0, 2,5% e 5% de casca de jabuticaba. Em seguida realizou-se análise da composição centesimal, polifenóis totais, antocianinas e capacidade antioxidante de diferentes extratos da casca de jabuticaba (CJ) e das barras. Com relação a analise sensorial o teste de aceitação com escala hedônica de 9 pontos e intenção de compra foi aplicado. A composição centesimal mostrou que as barras são constituídas basicamente de carboidratos (80%), água (10%) e proteínas (7%). Em relação ao perfil antioxidante, CJ apresenta atividade antioxidante para o método de ORAC e FRAP (483810,0 e 814684,8 µmol TE g-1 respectivamente em extrato metanol/acetona), compostos fenólicos totais e antocianinas em quantidades expressivas (131,29 gGAE.kg-1, em extrato aquoso e 342,0 mg cianidina 3-glicosídeo 100g-1, respectivamente). A atividade antioxidante, conteúdo de compostos fenólicos e antocianinas das barras de cereais apresentaram-se maiores quando adicionadas de 5% de casca de jabuticaba. No teste de aceitação, as barras que foram adicionadas com 2,5% e 5% de casca de jabuticaba, adoçadas com açúcar, obtiveram as melhores notas para o teste de aceitação. O mesmo resultado foi encontrado para o teste de intenção de compra. Os resultados indicam que as formulações das barras de cereais foram adequadas e geraram produtos aceitos pelos consumidores, além de apresentarem compostos bioativos com atividade antioxidante importante / Abstract: Cereal bars are a source of nutrients, easy to use and require no preparation by the consumer. Their consumption has been growing recently. They have varied composition, are consisting of various cereals, and can be added ingredients such as fruits, nuts, chocolate and others. The use of sweeteners is also growing due to the large number of people with diabetes, or who make their use for weight control. Furthermore, some ingredients of cereal bars (fruit, nuts) have antioxidant activity important, combating free radicals, in order to prevent imbalance in the redox state and oxidative stress in cells of the body. The peel of jaboticaba (Myrciaria jaboticaba (Vell) Berg.), is rich in anthocyanins and phenolics, providing a supply of bioactive compounds with antioxidant activity expressive. The objective of this study was to formulate cereal bars with sucrose and sweeteners (stevia and sucralose) adding different concentrations jaboticaba peel, and evaluating their antioxidant activity and acceptance through sensory test. Were formulated cereal bars containing 0, 2.5% and 5% jaboticaba. Then analysis was performed of the centesimal composition, polyphenols, anthocyanins and antioxidant capacity of different extracts the jaboticaba peel (CJ). Regarding analyze sensory the acceptance testing with 9 point hedonic scale and purchase intent were applied. The centesimal composition showed that the bars consist primarily of carbohydrates (80%), water (10%) and proteins (7%). In relation to the antioxidant profile, CJ has antioxidant activity for the ORAC and FRAP methods (483810,0 and 814684,8 µmol TE g-1 respectively extract methanol / acetone) and total phenolics and anthocyanins in significant amounts (131.29 gGAE.kg-1 in aqueous extract and 342.0 mg cyanidin 3-glucoside 100 g-1, respectively). A antioxidant activity, phenolic compounds and anthocyanins of cereal bars present greater when added 5% the jaboticaba peel. In the acceptance test, bars that were added with 2.5% and 5% jaboticaba peel sweetened with sugar obtained the highest grades for acceptance testing. The same result was found for the test purchase intent. The results indicate that the formulations of the cereal bars were adequate and generated products accepted by consumers, besides presenting bioactive compounds with antioxidant activity important / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestra em Alimentos e Nutrição

This research study analysed the role that experience played in the development of bar managers’ social competencies. Given the social nature of the bar environment, social competencies were perceived to be essential managerial competencies that enable bar managers to manage employees and consumers to ensure that employee and consumer satisfaction is maintained. The literature reviewed discussed the importance of managerial competencies and the composition of social competencies. Experience was conceptualized to develop an understanding of the informal learning method through which competency development occurs. Data was captured through face-to-face interviews, which were based on the Critical Incident Technique (CIT). The data was analysed using the open coding procedures of grounded theory. This research study proposed a process to explain how experience contributed to the development of social competencies. The proposed process, which is called the Social Competency Cache Development Process (SCCD Process), ultimately indicated that experience contributed to bar managers’ social competencies through a reflection process, the residues of experience, and through the familiarity of situations and results. This research study found that experience contributed to the development of bar managers’ social competencies within a process that established an awareness of unfamiliar social competencies or reinforced the effects of familiar effective social competencies. Experience was also found to promote the transition between novel situations and familiar situations, which in turn enabled bar managers to effectively assess social situations and select effective responses to social situations. Consequently, experience improved the probability of bar managers implementing effective social competencies to ensure employee and consumer satisfaction. In essence, experience shaped bar managers’ accumulation of social competencies by promoting the addition of new social competencies or the reinforcement of existing social competencies.

Dowel bars are provided at the transverse joints of the Jointed Plain Concrete Pavement (JPCP) to transfer the load between adjoining slabs and to allow for expansion and contraction of the pavement due to temperature and moisture changes. The current study involved evaluation of the performance of Glass Fibre Reinforced Polymer (GFRP) dowels in JPCP as an alternative to the conventional epoxy-coated steel dowel bars, especially in the presence of dowel misalignment. This research involved two main sets of experimental tests. The first set focused on the evaluation of load-deflection response of GFRP dowels using a scaled model of pavement slabs. The second set investigated the combined effect of dowel misalignment and cyclic wheel load on the performance of steel and GFRP dowels. The tested slabs (in the second set) were supported on a steel-beam base with stiffness such that the effects of the underlying layers of real pavements are incorporated. In both of these sets of experiment the GFRP dowels were compared with the steel dowels of similar flexural rigidity. The research also involved detailed numerical investigations using ABAQUS for all experimental tests in the current study. The validated numerical model was used to conduct three sets of parametric studies: to propose design considerations for the GFRP dowels; to simulate all important cases of dowel misalignment (111 cases) for steel and GFRP dowels and to give an insight into the damaged volume in the surrounding concrete pavement; and to investigate the effects of diameter, length and type of dowel bar, concrete grade, pavement thickness, and slab-base friction on the joint-opening behaviour. The results from the first set of experiments showed that the 38 mm GFRP dowels perform better in terms of deflection response compared to the 25 mm steel dowels. Also, it was observed that the relative deflection (RD) is more sensitive to the changes in the joint width rather than the concrete strength. The numerical results from the first set showed a good agreement with the experimental results and showed lower magnitude and better distribution of stress in the concrete underneath the GFRP dowels as compared with the steel dowels. Finally, on the basis of a detailed parametric study (70 different cases), design considerations for GFRP dowels in JPCP were suggested. The second set of experimental results showed that the GFRP dowels can withstand a cyclic traffic load and significantly reduce joint lockup and dowel looseness (DL) and can provide sufficient load transfer efficiency (LTE). It was also observed that the dowel misalignment affects DL significantly more than the repeated traffic load. Slab-base separation and the orientation of misaligned dowels have significant effects on the pull-out load required to open the joint. The numerical results from the second set indicated that the pull-out load was small for the vertical misalignment cases compared to the horizontal and combined misalignment cases. The results also indicated the occurrence of concrete spalling and deterioration at smaller joint openings for combined misalignment when compared to other misalignment types. The use of GFRP dowels significantly reduced the pull-out load and joint lockup when dowel misalignment exists. Consequently, the deterioration of the surrounding pavement substantially decreased. The long term performance of the JPCP fitted with GFRP dowels improves because of a reduction in the DL and the RD, and by maintaining a good LTE even for misaligned dowels. The numerical results also showed that the pull-out load increases significantly for an increase in the concrete compressive strength and the dowel bar diameter. Small increase in pull-out load was observed for higher embedded length of the dowel bar, whereas the increase was insignificant for an increase in the pavement thickness and slab-base friction. In general, the study showed the GFRP dowel can be a potential alternative for the conventional steel dowel bars in JPCP.

Various nondestructive testing (NDT) technologies for construction and performance monitoring have been studied for decades. Recently, the rapid evolution of wireless sensor network (WSN) technologies has enabled the development of sensors that can be embedded in concrete to monitor the structural health of infrastructure. Such sensors can be buried inside concrete and they can collect and report valuable volumetric data related to the health of a structure during and/or after construction. Wireless embedded sensors monitoring system is also a promising solution for decreasing the high installation and maintenance cost of the conventional wire based monitoring systems. Wireless monitoring sensors need to operate for long time. However, sensor batteries have finite life-time. Therefore, in order to enable long operational life of wireless sensors, novel wireless powering methods, which can charge the sensors’ rechargeable batteries wirelessly, need to be developed. The optimization of RF wireless powering of sensors embedded in concrete is studied here. First, our analytical results focus on calculating the transmission loss and propagation loss of electromagnetic waves penetrating into plain concrete at different humidity conditions for various frequencies. This analysis specifically leads to the identification of an optimum frequency range within 20-80 MHz that is validated through full-wave electromagnetic simulations. Second, the effects of various reinforced bar configurations on the efficiency of wireless powering are investigated. Specifically, effects of the following factors are studied: rebar types, rebar period, rebar radius, depth inside concrete, and offset placement. This analysis leads to the identification of the 902-928 MHz ISM band as the optimum power transmission frequency range for sensors embedded in reinforced concrete, since antennas working in this band are less sensitive to the effects of varying humidity as well as rebar configurations. Finally, optimized rectennas are designed for receiving and/or harvesting power in order to charge the rechargeable batteries of the embedded sensors. Such optimized wireless powering systems exhibit significantly larger efficiencies than the efficiencies of conventional RF wireless powering systems for sensors embedded in plain or reinforced concrete.

L'objectif de ce mémoire est de comprendre le fonctionnement hydro-sédimentaire des embouchures tidales dominées par la marée et la construction d'une flèche sableuse à crochets perpendiculaires. Deux sites voisins ont été choisis : les embouchures de l'Orne et de la Dives sur la côte du Calvados (Normandie). L'utilisation de données d'agitation et topographiques, acquises selon plusieurs échelles spatio-temporelles, permet d'étudier la morphodynamique de ces deux embouchures.L'embouchure de l'Orne possède une évolution soumise à une forte pression anthropique causée par de nombreuses infrastructures portuaires. Elle est comparée à celle de l'embouchure de la Dives, où l'impact anthropique est plus limité. Il apparaît que ces deux embouchures partagent les mêmes mécanismes de transports sédimentaires, avec une composante transversale importante. Ce transport vers la côte est assuré par la migration de barres de swash sur les parties aval-dérive des deltas de jusant. Ces barres de swash possèdent des volumes et des vitesses de migration similaires, comprises entre 3.5 et 8.0 m/mois.Contrairement à la Dives, les côtes en amont et en aval-dérive de l'embouchure de l'Orne sont en accrétion. Si en amont, cette accrétion suit les nombreuses phases de construction du port de Caen-Ouistreham, en aval se développe depuis un peu plus d'un siècle une flèche sableuse à la morphologie atypique. En effet, cette flèche possède plusieurs crochons emboités, dont les extrémités - les crochets - sont perpendiculaires au corps à la flèche. Il est démontré que l'attachement des barres de swash à la côte est responsable de la formation d'un nouveau crochon. La diffraction des vagues au niveau de l'extrémité des barres de swash et des crochons, ainsi que les directions locales de l'agitation, expliquent la formation des crochets perpendiculaires à l'extrémité des crochons. / The aim of this thesis is to understand the mechanisms of sediment bypassing at tidal inlets in a macrotidal environment and the formation of a sandspit with perpendicular hooks. Two closed areas are studied, the Orne and Dives inlets on the coast of Normandy (France). Wave and topographic data, at several space-time scales, are used to study the inlet morphodynamics.The Orne inlet is affected by strong human impacts due to several port facilities whereas the Dives inlet knows a limited anthropogenic impact. The study of the two inlets allows to deduce the impact of the human activities in the sediment transport patterns. The Orne and Dives inlets share the same mechanisms of sediment transport. Both show a major cross-shore component of the transport, underlines by the swash bars migration over the ebb-tidal deltas. All swash bars have similar volumes and migration rates, between 3.5 and 8.0 m/month.The Orne inlet shows deposition on both sides. The accretion on the updrift coast follows the building stages of the harbour of Caen-Ouistreham. On the downdrift coast, the deposition creates the Merville spit, which has several interlocked ridges. A perpendicular hook is present on the distal part of each ridge. This work shows that the swash bar attachment at the shoreline shapes a new ridge. Wave diffraction around the distal part of the swash bars and ridges, and the local wave directions, explain the formation of perpendicular hooks.