La récupération d'énergie ambiante permet d’alimenter de manière autonome des systèmes de petite taille tels que des neouds de capteurs ou des objets connectés à internet (IoT) en remplacement des batteries. Les sources d’énergie ambiante sont par exemple, l’énergie solaire, le gradient thermique, les forces mécaniques, le rayonnement électromagnétique et la pile microbienne. Les matériaux piézoélectriques permettent de valoriser électriquement l’énergie mécanique de vibration en la convertissant directement en énergie électrique. Les niveaux de puissance assez faible (de quelques μW au mW) ont amené à développer des interfaces électriques de récupération afin d’extraire le maximum d'énergie en améliorant le couplage électromécanique. Dans ce travail, nous nous intéressons à l’amélioration de dispositif de récupération d’énergie. Deux aspects sont abordés : dans un premier temps l’étude d’un commutateur hybride synchrone électrique-mécanique est faite pour remplacer le transistor MOSFET couramment utilisé, afin de réduire sa consommation d’énergie ; dans un deuxième temps, un travail est mené sur une nouvelle structure mécanique à base de poutres reliées entre elle par des forces de répulsion magnétique. La structure obtenue par cet ensemble de poutres et de type non-linéaire à plusieurs degrés de liberté (MDOF) ce qui permet augmenter la bande passante. / The future trend of Internet of Things (IoT) is bringing energy harvesting in to the core technique due to its requirement of self-power supplying. For best customer interface and eco-friendly issues, additional sensing systems are to be designed small, wireless and self-powering. Energy harvesting provides a way to realize the wireless self-powered system, it enables the device itself to obtain its own energy from their environment. Solar energy, thermal gradient, mechanical forces, are some commonly seen methods to obtain energy from the environment. The piezoelectric energy harvester is chosen to harvest vibrational energy in this study. In this work, a simple model of the original electrical smart switch driven under ultra-low power is proposed. By using the miniature device to drive the smart switch, the efficiency when low power is provided was examined. To construct an energy harvesting system in a more complete aspect, two newly proposed methods are as below: First, the hybrid-electrical-mechanical switches were utilized to replace the commonly seen electrical smart switches, to reduce its energy consumption such as threshold loss. Secondly, we designed a new mechanical structure for the cantilever array by connecting the beams using magnetic repelling force. In this way, the beams within the array were connected physically, forming a nonlinear multi-degree of freedom (MDOF) -like result.

This master thesis deals with the electron beam welding of the AMS 5659 steel used in industry for special hydraulic cylinders (Fig. 1). A theoretical analysis of electron beam welding and analysis of the influence of selected welding parameters on penetration characteristics are in the first part of the thesis. The second part contains an evaluation of the implemented experimental penetrations on samples of the steel in the hardened condition H1025 and after solution heat. It was also done a properties assessment of the same samples that were been hardened again. The light microscopy (SM), the scanning electron microscopy (SEM) and the measurement method of hardness according to Vickers were used for evaluation and comparison of the steel properties in the region of penetration and the heat affected zones properties.

The current trend in the design of steel structures leads, due to the saving of the material, to the frequent use of thin-walled cold formed steel sections. Thin cold-formed steel profiles are often manufactured with web holes. A specific example of thin-walled steel profiles are Sigma beams used in additionally installed built-in floors systems in warehouses. The aim of doctoral thesis is the analysis, assessment and experimental verification of the technical solution of thin-walled steel beams with web openings loaded in bending with respect to lateral torsional buckling. The objective is to develop knowledge about the real properties of steel members of considered structural arrangement in order to specify the methods of analysis and design in industrial practice. The theoretical analysis describes the behavior of the beams by means of solving the differential equations of the equilibrium on deformed element of thin walled member under bending. In case of beams with web holes is used the solution in the form of introduction of substitute cross-section properties, which are defined as the weighted average of the properties of full and weakened section. The numerical analysis is focused on the use of commonly available software in order to predict the bending resistance of beams with web opening with respect to lateral torsional buckling. Since the software used in practice solves only the prismatic beams without option to model the web openings, it is in frame of numerical analysis verified the model of beam with reduced thickness of web constantly over the whole beam length in the zone of perforation. The experimental analysis is firstly focusing on the verification of real bending and torsion stiffness of the beams, based on which are being derived the values of basic cross-sectional properties. Subsequently the experimental verification of real bending resistance with respect to the lateral torsional buckling is being performed.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20377号 / 工博第4314号 / 新制||工||1668(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 篠原 真毅, 教授 和田 修己, 教授 大村 善治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Hydroakustiska mätningar har gjorts i nästan två hundra år. Det kan liknas med topografiska mätningar på land och visar hur sjö- eller havsbottnar ser ut. Idag används ekolod vilket är en teknik som skickar ut ljudvågor i vattnet för att mäta hur lång tid det tar för ljudet att studsa på bottnen och sedan komma upp till instrumentet igen. Därefter går det att räkna ut djupet med hjälp av ljudhastighetsberäkningar. Vid inmätning av enkelstråligt ekolod rekommenderas användande av tvärsektioner som kontroll av data. Flerstråligt ekolod behöver däremot inte tvärsektioner då övertäckning mellan stråken används som kontroll. I denna studie undersöks hur antalet tvärsektioner påverkar djupkartor skapade av Seafloor HydroLite TM enkelstråligt ekolod. Detta är även en undersökning av hur djupkartor producerade av SeaFloor HydroLite TM enkelstråligt ekolod skiljer sig mot djupkartor producerade av Kongsberg EM 2040 MK11 flerstråligt ekolod. Studieområdet är 1820 m2 och är beläget vid Forsbackas hamn i Storsjön, Gävle kommun. Vid inmätning av flerstråligt ekolod användes en övertäckning av lägst 50 %. Fem huvudstråk och sju tvärsektioner mättes med enkelstråligt ekolod för området. Djupkartor med olika antal tvärsektioner gjordes i Surfer 10 från enkelstråligt ekolod. Därefter jämfördes djupkartor av enkelstråligt ekolod mot kartor gjorda av data från flerstråligt ekolod för att se hur djupkartorna skiljer sig och för att se hur djupkartorna av enkelstråligt ekolod påverkas av olika antal tvärsektioner. Med användande av flerstråligt ekolod som referens mot djupkartor gjorda av enkelstråligt ekolod blev resultaten att RMS och standardosäkerhet minskar med 1 cm i RMS-värde och med 2 cm i standardosäkerhet. Jämförelse mellan ekolods systemen visar att skillnaden av djupvärderna är runt 10 cm. Slutsatserna från denna studie är att tvärsektioner endast förbättrar kvalitén på djupkartor marginellt vid jämn och enhetlig bottentopografi, men fyller en viktig funktion genom att kontrollera kvalitén av inmätningsdatat. Samt att SeaFloor HydroLite TM klarar av order 1b vid ett djup omkring en till fyra meter om ej kravet på full bottentäckning beaktas. Seafloor HydroLite TM skapar en översiktlig djupkarta medan djupmodellerna från Kongsberg EM 2040 MKII ser mera detaljer. / Hydroacoustic measurements have been conducted for almost two hundred years. It can be compared to topographic measurements on land and shows the appearance of lake or ocean floors. Today, echosounders are used, which is a technique that sends out sound waves into the water to measure the time it takes for the sound to bounce off the bottom and return to the instrument. Sound velocity calculations can then be used to calculate the depth. The use of cross-sections is recommended as a data control of single beam echosounder. However, multi beam echosounders only use overlap as control. This study examines how the number of cross-sections affects depth maps created by Seafloor HydroLite TM single beam echosounder. It also investigates the differences between depth maps produced by the SeaFloor HydroLite TM single beam echosounder and the Kongsberg EM 2040 MK11 multi beam echosounder. The study area covers 1820 m2 and is located at Forsbackas Harbor in Storsjön, Gävle municipality. A minimum overlap of 50% was used for the surveying with the multi beam echosounder. Five main lines and seven cross-sections were measured using the single beam echosounder. Depth maps with different numbers of cross-sections were created using data from the single beam echosounder. The maps from the single beam echosounder were compared to maps created from the data obtained by the multi beam echosounder to assess the differences and the impact of varying numbers of cross-sections on the depth maps from the single beam echosounder. By using the multi beam echosounder as a reference for the depth maps created by the single beam echosounder, the results showed a decrease of 1 cm in RMS value and 2 cm in standard deviation. The comparison between the echosounder systems revealed a difference of around 10 cm in depth values. The conclusions from this study are that cross-sections only marginally improve the quality of depth maps in cases of even and uniform bottom topography but serve an important function in validating the quality of the survey data. Additionally, the SeaFloor HydroLite TM is capable of meeting Order 1b at depths ranging from one to four meters if the requirement for full bottom coverage is not considered. The Seafloor HydroLite TM creates a general overview of the depth map, while the depth models from the Kongsberg EM 2040 MKII provide more detailed information.

<p>The Mechanics of Structural Genome (MSG) is a unified homogenization theory used to find equivalent constitutive models for beam, plate, and solid structures. It has been proven accurate for periodic structures. However, for certain applications such as non-prismatic wind turbine blades and helicopter flexbeams featuring ply drop-off, where there is no repeating structure and the periodic boundary condition cannot be used, MSG's accuracy is limited. In this work, we aim to extend MSG to find element stiffness matrices directly for aperiodic structures, instead of beam properties or three-dimensional (3D) solid material properties. Two finite elements based on MSG have been developed: Heterogeneous Beam Element (HBE) and Heterogeneous Solid Element (HSE).</p> <p><br></p> <p>For beam modeling, the beam-like structure is homogenized into a series of 3-node Heterogeneous Beam Elements (HBE) with 18×18 effective beam element stiffness matrices. These matrices are used as input for one-dimensional (1D) beam analysis using the Abaqus User Element subroutine (UEL). Using the macroscopic beam analysis results as input, we can also perform dehomogenization to predict the stresses and strains in the original structure. We use three examples (a prismatic composite beam, an isotropic homogeneous tapered beam, and a composite tapered beam) to demonstrate the capability of HBE and show its advantages over the MSG cross-sectional analysis approach. HBE can capture macroscopic behavior and detailed stresses due to non-prismatic geometry.</p> <p><br></p> <p>The Heterogeneous Solid Element (HSE) is developed based on MSG to model a heterogeneous body as an equivalent solid element using an effective element stiffness matrix. HSE modeling includes homogenization, macroscopic global analysis, and dehomogenization to recover local strains/stresses. HSE avoids the local periodicity assumption for traditional multiscale modeling techniques for composite structures that compute effective material properties instead. Abaqus composite solid element and MSG-based traditional multiscale modeling are used to validate the accuracy of HSE. All example results show that HSE is more accurate in predicting global structural behavior and local strains/stresses.</p> <p><br></p> <p>HBE and HSE provide a new concept for modeling aperiodic composite structures by modeling structures into equivalent beam or solid elements instead of beam properties of the reference line in 1D beam analysis or material properties of material points in solid structural analysis.</p>

[pt] A presença de aminoácidos em cometas e meteoritos levanta questões sobre como estes foram formados em ambientes cósmicos, bem como de que maneira eles foram capazes de sobreviver no espaço sideral; radioresistência é uma informação essencial para prever meias-vidas e avançar os estudos sobre origens da vida. O principal objetivo deste trabalho é determinar, por meio de espectroscopia no infravermelho, as seções de choque de destruição de aminoácidos comuns expostos à radiação de íons e elétrons energéticos. As forças de banda vibracionais (A-values) e a dependência do espectro infravermelho com a temperatura da amostra (10 – 400 K) foram analisadas. Seções de choque de destruição aparente (sigma)d(ap) e rendimentos de sputtering (Y0) para glicina, valina e fenilalanina irradiadas por H+, He+ e Nq+ íons de MeV e elétrons de keV foram medidos. Encontrou-se: i) uma dependência aproximadamente linear entre a seção de choque de destruição aparente e o poder de freamento eletrônico (Se): (sigma)d(ap) = (sigma)d + Y0 /N0 = a Sen (onde n aproximadamente 1) para projéteis de MeV e para amostras à temperatura ambiente; ii) resultados preliminares de σdap para feixes de nitrogênio multi-carregados; e iii) resultados de seção de choque de destruição de valina irradiada por elétrons de keV, bem como sua dependência com a energia de incidência do feixe, e com a espessura e temperatura da amostra. Como contribuição teórica, o modelo CASINO-estendido foi desenvolvido visando descrever a evolução da degradação de matéria orgânica por projéteis carregados, particularmente por feixes de elétrons. Comparadas aos resultados experimentais, as previsões do modelo subestimam o dano causado pelo feixe de elétrons, evidência de que efeitos de sputtering e provavelmente algumas características da amostra (como a estrutura cristalográfica) devem ser incluídos. Como implicações astrofísicas, meias-vidas para valina e fenilalanina irradiadas por raios cósmicos são estimadas em aproximadamente 10 milhões de anos no meio interestelar; da glicina, se irradiadas por vento solar a uma unidade astronômica do Sol, é aproximadamente 3 dias. Visando simular materiais astrofísicos realistas bombardeados por elétrons de keV, a meia-vida de valina envolta por gelos de água e CO2 e depositada sobre silicato é também prevista. / [en] The presence of amino acids in comets and meteorites raises questions about how they have been formed in cosmic environments, as well as how long they can survive in outer space; radioresistance is essential information to predict half-lives and make advances on the origins of life studies. The main objective of the current work is to determine, via infrared spectrometry, destruction cross sections of common amino acids exposed to energetic ion and electron radiation. Before sample irradiation, valine vibrational band strengths and their infrared spectral dependence on temperature (10 – 400 K) were analyzed. Apparent destruction cross sections (sigma)d(ap) and sputtering yields (Y0) for glycine, valine and phenylalanine, irradiated by MeV H+, He+ and Nq+ ions and keV electrons, were measured. From experimental data: i) an approximately linear dependence between the apparent destruction cross section and the electronic stopping power (Se) is found: (sigma)d(ap) = (sigma)d + Y0 /N0 = a Sen (where n approximately 1) for MeV projectiles and for samples at room temperature; ii) (sigma)d(ap) preliminary results relative to multi-charged nitrogen ion beams are discussed; and iii) destruction cross section of valine irradiated by keV electrons, as well as its dependence on incident beam energy, on sample thickness and on sample temperature are presented. As a theoretical contribution, the evolution of organic matter damage by charged projectiles, particularly for electron beams, the CASINO-extended model was developed. When compared to experimental results, the model predictions underestimate the damage caused by electron beams, evidence that sputtering and probably some sample characteristics (as crystallographic structure) are involved. As astrophysical implications, cosmic ray half-lives for valine and phenylalanine are estimated to be about 10 million years in the interstellar medium; solar wind half-life at 1 au from the Sun is approximately 3 days for glycine. Aiming to simulate realistic astrophysical materials bombarded by keV electrons, the half-life of valine embedded into water and CO2 ices over a silicate substrate is also predicted.

Bridge edge beam system is an increasing concern in Sweden. Because it is the mostvisible part of the structure which is subjected to harsh weather. The edge beamcontributes to the stiffness of overhang slab and helps to distribute the concentratedload. The design of edge beam is not only affected by the structural members, but it isalso affected by non-structural members.The aim of the thesis is to investigate the influence of edge beam on the structuralbehavior of reinforced concrete overhang slab. A three-dimensional (3D) non-linearfinite element model is developed by using the commercial software ABAQUS version6.1.14. The load displacement curves and failure modes were observed. The bendingmoment and shear capacity of the cantilever slab is studied.The validated model from non-linear analysis of reinforced concrete slab gives morestiffer result and leads to the high value of load capacity when comparing with theexperimental test. The presence of the edge beam in the overhang slab of length 2.4 mslightly increases the load capacity and shows ductile behavior due to the self-weightof the edge beam. The non-linear FE-analysis of overhang slab of length 10 m leads tomuch higher load capacity and gives stiffer response as compare to the overhang slabof 2.4 m. The presence of the edge beam in the overhang slab of length 10 m giveshigher load capacity and shows stiffer response when comparing with the overhangslab of length 10 m. This might be due to the self-weight of the edge beam and theoverhang slab is restrained at the right side of the slab.

Yes / A novel process chain for serial production of polymer-based devices incorporating both micro- and nano-scale features is proposed. The process chain is enabled by the use of Zr-based bulk metallic glasses (BMG) to achieve the necessary level of compatibility and complementarity between its component technologies. It integrates two different technologies, namely laser ablation and focused ion beam (FIB) milling for micro-structuring and sub-micron patterning, respectively, thus to fabricate inserts incorporating different length scale functional features. Two alternative laser sources, namely nano-second (NS) and pico-second (PS) lasers, were considered as potential candidates for the first step in this master-making process chain. The capabilities of the component technologies together with some issues associated with their integration were studied. To validate the replication performance of the produced masters, a Zr-based BMG insert was used to produce a small batch of micro-fluidic devices by micro-injection moulding. Furthermore, an experimental study was also carried out to determine whether it would be possible by NS laser ablation to structure the Zr-based BMG workpieces with a high surface integrity whilst retaining the BMG's non-crystalline morphology. Collectively, it was demonstrated that the proposed process chain could be a viable fabrication route for mass production of polymer devices incorporating different length scale features.

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