Un grand défi actuel consiste à réaliser des capteurs innovants tirant partie des propriétés singulières de nanoparticules colloïdales synthétisées par voie chimique et assemblées de manière contrôlée sur des surfaces. L’objet de cette thèse est le développement de jauges de contrainte résistives à base de nanoparticules. Ces jauges de contrainte sont constituées de lignes parallèles, de quelques micromètres de large, denses, de nanoparticules colloïdales d’or synthétisées par voie chimique et assemblées sur des substrats souples par assemblage convectif contrôlé. Le principe de ces capteurs résistifs repose sur la conduction tunnel entre les nanoparticules qui varie de manière exponentielle lorsque que l’assemblée est déformée. Des mesures électro-mécaniques couplées à des observations en microscopie électronique à balayage et à force atomique ont permis d’identifier, de quantifier et de comprendre l’impact de la taille et de la nature des ligands des nanoparticules sur la sensibilité et les phénomènes de dérive de la résistance à vide des jauges de contrainte. Ces travaux, associés à des mesures de diffusion de rayons X aux petits angles ont permis de corréler les variations macroscopiques de résistance électrique des jauges de contrainte aux déplacements relatifs des nanoparticules. Finalement, ces jauges de contrainte ultra-sensibles et miniatures, mises en matrices, ont été exploitées pour réaliser des surfaces tactiles souples multi-points et sensibles à l’intensité de l’appui / One recent big challenge is to implement innovative sensors that take advantage of the unique properties of colloidal nanoparticles chemically synthesized and assembled on various surfaces. The goal of this work is the development of nanoparticle based resistive strain gauges. These strain gauges are constructed of few micrometers wide parallel wires of close packed colloidal gold nanoparticles, chemically synthesized, and assembled on flexible substrates by convective self assembly. The principle of these resistive sensors is based on the tunnel conduction between the adjacent nanoparticles which varies exponentially as the assembly is stretched. Electro-mechanical measurements coupled with scanning electron microscopy and atomic force microscopy observations were used to identify, quantify and understand the impact of the nanoparticle size and the nature of the protecting ligands, on the gauge sensitivity and the drift of the resistance at rest of the nanoparticle based strain gauges. Coupled with small angle x-ray scattering measurements, these studies allowed us to correlate the macroscopic changes in electrical resistance of the strain gauges to the relative displacement of the nanoparticles at the nanoscale. Finally, a matrix of these miniature ultra-sensitive gauges was used to construct flexible touch screen panels capable of measuring the intensity of several touches simultaneously

Orientador: José Antonio Siqueira Dias / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-26T13:53:46Z (GMT). No. of bitstreams: 1 Tercariol_WalterLuis_D.pdf: 1322557 bytes, checksum: 4f45518a1a62907cd9a61afa627408c3 (MD5) Previous issue date: 2014 / Resumo: Este trabalho visa compilar três contribuições na melhoria dos projetos de reguladores de tensão com unidades de bombeamento de carga embutidos (células elevadoras de tensão Dickson - BC). A primeira aborda uma técnica inovadora de arranque na partida deste módulo elevador quando habilitado. Este projeto se refere à aceleração da inicialização do modulo BC, tendo como objetivo a diminuição do intervalo de tempo da rampa ascendente da tensão de saída Vo até atingir o nível alvo de regulação. A técnica consiste em gerenciar o aumento da freqüência do relógio de bombeamento entregue as unidades de bombeamento durante a fase de subida, quando a regulação estiver estabelecida o sistema se regenera voltando ao estado original de freqüência de bombeamento natural. Uma segunda proposta inovadora de projeto é referente à homogeneização e redução da aleatoriedade da ondulação da tensão de saída Vo, referente ao regulador com o modulo BC embutido, baseado em comparadores com trava, com proposta de redução do erro de comparação devido ao efeito aleatório durante o estagio de comparação comumente encontrado neste tipo de abordagem, a técnica consiste em suprimir o acoplamento capacitivo nocivo durante a fase de isolamento elétrico no processo de comparação mantendo o espelho de corrente do comparador na região de saturação. Esta técnica visa proporcionar uma redução significativa da capacitância de desacoplamento utilizada para filtragem da tensão Vo. Uma terceira e última contribuição é referente a uma inovadora técnica de medição indireta da tensão de saída Vo do regulador com módulo BC baseada em uma medida simples e precisa dos pares tensão da porta e fonte (VPS) e corrente elétrica do dreno (Idreno) de um dispositivo NMOS de alta tensão adicionado de modo que duas tensões conhecidas (preestabelecidas) são aplicadas na porta do dispositivo e as respectivas correntes de dreno são mensuradas e uma terceira desconhecida (oriunda do regulador elevador BC) desconhecida pode ser extrapolada de forma simples. Esta técnica visa ser útil para medição de reguladores de baixa potencia pois o carregamento do regulador (Vo) é quase nulo.Todas as inovações e melhorias propostas foram analisadas em veículos de teste (silício) e com as provas de conceito, feitas em simulações elétricas / Abstract: This work aims to compile contributions in improving designs based on voltage regulators with voltage elevator with built-in charge pump CP. The first deals with an innovative technique rump-up this module when enabled. This project refers to the acceleration of startup the CP module, aiming at the reduction of the period of stabilization of the ramp output voltage Vo to the level of regulation target. The technique is to manage increasing the frequency of pumping clock during the phase of rump up and when the setting established the system regenerates back to the original state pumping frequency. A second innovative project proposal was made on the homogenization and reduction of the ripple of the output voltage Vo, referring to the regulator with the |CP module, based on latch comparators , alignment error reduction proposal because of the random effect during the stage comparison commonly found in this type of approach, the technique is to remove the harmful capacitive coupling during electrical isolation phase on the comparison keeping the comparator current mirror in saturation region. This technique aims to provide a significant reduction in the decoupling capacitance used for filtering the voltage Vo. A third and final contribution is related to an innovative technique of indirect measurement of the output voltage Vo of the regulator module CP, based on a simple and accurate measure of the gate voltage and couples the drain electric current of a high voltage NMOS device / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

Introduction: Muscle fatigue can contribute to acute flare-ups of lower back pain with associated consequences such as pain, disability, lost work time, increased healthcare utilization, and increased opioid use and potential abuse. The SPINE Sense system is a wearable device with 16 high deflection nanocomposite strain gauge sensors on kinesiology tape which is adhered to the skin of the lower back. This device is used to correlate lumbar skin strains with the motion of the lumbar vertebrae and to phenotype lumbar spine motion. In this work it was hypothesized that the SPINE Sense device can be used to detect differences in biomechanical movements consequent to muscle fatigue. A human subject study was completed with 30 subjects who performed 14 functional movements before and after fatiguing their back muscles through the Biering-Sørensen endurance test with the SPINE Sense device on their lower back collecting skin strain data. Various features from the strain gauge sensors were extracted from these data and were used as inputs to a random forest classification machine learning model. The accuracy of the model was assessed under two training/validation conditions, namely a hold-out method and a leave-one-out method. The random forest classification models were able to achieve up to 84.22% and 78.37% accuracies for the hold-out and leave-one-out methods respectively. Additionally, a system usability study was performed by presenting the device to 32 potential users (clinicians and individuals with lower back pain) of their device. They received a scripted explanation of the use of the device and were then instructed to score it with the validated System Usability Score. In addition they were given the opportunity to voice concerns, questions, and offer any other additional feedback about the design and use of the device. The average System Usability Score from all participants from the system usability study was 72.03 with suggestions of improving the robustness of electrical connections and smaller profiles of accompanying electronics. Feedback from the potential users of the device was used to make more robust electrical connections and smaller wires and electronics modules. These improvements were achieved by making a two-piece design: one piece contains the sensors on kinesiology tape that is directly attached to the patient and the other one contains the wires sewn into stretch fabric to create stretchable electronic connections to the device. It is concluded that a machine-learning model of the data from the SPINE Sense device can classify lumbar motion with sufficient accuracy for clinical utility. It is also concluded that the device is usable and intuitive to use.

Recent developments in constructions have heightened the need for protecting existing buried infrastructure. New roads and buildings may be constructed over already existing buried infrastructures e.g. buried utility pipes, leading to excessive loads threatening their stability and longevity. Additionally applied loads over water mains led to catastrophic damage, which result in severe damage to the infrastructure surrounding these mains. Therefore, providing protection to these existing buried infrastructure against increased loads due to new constructions is important and necessary. In this research, a solution was proposed and assessed, where the protection concept would be achieved through the inclusion process of geogrid-reinforcing layers in the soil cover above the buried infrastructure. The controlling parameters for the inclusion of geogrid-reinforcing layers was assessed experimentally and numerically. Twenty-three laboratory tests were conducted on buried flexible and rigid pipes under unreinforced and geogrid-reinforced sand beds. All the investigated systems were subjected to incrementally increasing cyclic loading, where the contribution of varying the burial depth of the pipe and the number of the geogrid-reinforcing layers on the overall behaviour of the systems was investigated. To further investigate the contribution of the controlling parameters in the pipe-soil systems performance, thirty-five numerical models were performed using Abaqus software. The contribution of increasing the amplitude of the applied cyclic loading, the number of the geogrid-reinforcing layers, the burial depth of the pipe and the unit-weight of the backfill soil was investigated numerically. The inclusion of the geogrid-reinforcing layers in the investigated pipe-soil systems had a significant influence on decreasing the transferred pressure to the crown of the pipe, generated strains along its crown, invert and spring-line, and its deformation, where reinforcing-layers sustained tensile strains. Concerning rigid pipes, the inclusion of the reinforcing-layers controlled the rebound that occurred in their invert deformation. With respect to the numerical investigation, increasing the number of the reinforcing-layers, the burial depth of the pipe and the unit-weight of the backfill soil had positive effect in decreasing the generated deformations, stresses and strains in the system, until reaching an optimum value for each parameter. Increasing the amplitude of the applied loading profile resulted in remarkable increase in the deformations, stresses and strains generated in the system. Moreover, the location of the maximum tensile strain generated in the soil was varied, as well as the reinforcing-layer, which suffered the maximum tensile strain. / Government of Egypt

This work presents a systematic study of the mechanochemical processes leading to chemical reactions occurring due to effects of high-strain-rate deformation associated with uniaxial strain and uniaxial stress impact loading in highly heterogeneous metal powder-based reactive materials, specifically compacted mixtures of Ti/Al/B powders. This system was selected because of the large exothermic heat of reaction in the Ti+2B reaction, which can support the subsequent Al-combustion reaction. The unique deformation state achievable by such high-pressure loading methods can drive chemical reactions, mediated by microstructure-dependent meso-scale phenomena. Design of the next generation of multifunctional energetic structural materials (MESMs) consisting of metal-metal mixtures requires an understanding of the mechanochemical processes leading to chemical reactions under dynamic loading to properly engineer the materials. The highly heterogeneous and hierarchical microstructures inherent in compacted powder mixtures further complicate understanding of the mechanochemical origins of shock-induced reaction events due to the disparate length and time scales involved. A two-pronged approach is taken where impact experiments in both the uniaxial stress (rod-on-anvil Taylor impact experiments) and uniaxial strain (instrumented parallel-plate gas-gun experiments) load configurations are performed in conjunction with highly-resolved microstructure-based simulations replicating the experimental setup. The simulations capture the bulk response of the powder to the loading, and provide a look at the meso-scale deformation features observed under conditions of uniaxial stress or strain. Experiments under uniaxial stress loading reveal an optimal stoichiometry for Ti+2B mixtures containing up to 50% Al by volume, based on a reduced impact velocity threshold required for impact-induced reaction initiation as evidenced by observation of light emission. Uniaxial strain experiments on the Ti+2B binary mixture show possible expanded states in the powder at pressures greater than 6 GPa, consistent with the Ballotechnic hypothesis for shock-induced chemical reactions. Rise-time dispersive signatures are consistently observed under uniaxial strain loading, indicating complex compaction phenomena, which are reproducible by the meso-scale simulations. The simulations show the prevalence of shear banding and particle agglomeration in the uniaxial stress case, providing a possible rationale for the lower observed reaction threshold. Bulk shock response is captured by the uniaxial strain meso-scale simulations and is compared with PVDF stress gauge and VISAR traces to validate the simulation scheme. The simulations also reveal the meso-mechanical origins of the wave dispersion experimentally recorded by PVDF stress gauges.

To better manage deteriorating infrastructure, quantitative data about the performance of infrastructure assets is required. Rayleigh based distributed fibre optic strain sensing (FOS) is a technology that has the potential to offer this type of data and unlike traditional strain sensors it can measure the strain along the full length of the structure. A series of experiments were undertaken to develop installation techniques and evaluate sensor accuracy for typical civil engineering materials: steel, concrete and reinforced concrete. The results of these experiments showed that the choice of sensing fibre and adhesive was dependent on the material being monitored. When the sensing fibre and adhesive are chosen correctly, the Rayleigh system can provide the same accuracy as a strain gauge for steel and concrete, and useful measurements can be obtained even in areas of concrete cracking. The FOS technique was utilized to determine whether distributed strain measurements could be used to detect and quantify localized deterioration of the steel reinforcement (localized area reductions of 0-30%) at service loads. A series of specimens was tested, the sensing system was able to detect the presence of localized deterioration with embedded nylon and polyimide fibres, but the nylon fibre cannot quantify large strain gradients due to slip within the sensing fibre. The strain profiles gave insights to the failure mechanism occurring in the reinforced concrete specimens. The strain profiles for both test series indicated that the tension reinforcement was acting as a tension tie and the strain profiles suggested the presence of compressive struts indicative of an arching mechanism in the specimens. The Black River bridge in Madoc, Ontario was instrumented with fibre optics sensors to determine whether the use of FOS is both practical and beneficial for reinforced concrete bridge assessment when compared to conventional instrumentation. The FOS showed reasonably good agreement with conventional sensors. The fibre optic strain results are used to calculate curvature, slope and displacement but careful consideration of the boundary conditions is required. The results from the fibre optic sensors can be used to show the bridge load distribution and give insights into the support conditions of the beams. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-08-21 11:56:53.276

Cette thèse étudie différents problèmes de minimisations avec des fonctions de régularisations qui promeuvent la parcimonie. Plus précisément, on souhaite reconstruire une image, que l'on suppose parcimonieuse et qui a subit une transformation après un opérateur linéaire, à l'aide de problèmes de minimisations. Dans ce manuscrit, on s'intéressera plus particulièrement à la minimisation l1 synthèse, analyse et bloc qui sont très utilisées pour reconstruction une image que l'on sait parcimonieuse. Ces minimisations produisent en pratique des résultats convaincants qui n'ont été compris théoriquement que récemment. Les différents travaux sur le sujet mettent en évidence le rôle d'un vecteur particulier appelé certificat dual. L'existence d'un certificat dual permet à la fois d'assurer la reconstruction exacte d'une image dans le cas où il n'y a pas de perturbations et d'estimer l'erreur de la reconstruction en présence de perturbations. Dans nos travaux, nous allons introduire l'existence d'un certifical dual optimal pour la minimisation l1 synthèse qui minimisent l'erreur de reconstruction. Ces résultats ayant une forte interprétation géométrique, nous avons développé un critère identifiabilité, c'est à dire que ce critère assure que l'image recherchée est l'unique solution du problème de minimisation. Ce critère permet d'étendre nos travaux à la minimisation l1 analyse, l1 bloc et à d'autres cas. / This thesis studies different minimization problems with sparses based regularization. More precisely, we want to reconstruct a sparses image, which undergone a linear transformation, with minimization problems. In this manuscript, we will be focused on l1 synthesis, analysis and block minimization which are widely used in sparse approximations. These problems offer competitive results which are theorietical understood only recntly. Different studies on the subject emphasized the contribution of a particular vector called dual certificate. The existence of this dual certificate allows simultaneously to guarantee the exact recovey of an image in noiseless case and to estimate the noise robustness in noisy case. In this work, we introduce eth existence of an optimal dual certificate for the l1 synthesis minimization which minimizes the reconstruction error. As those results have a strong geometrical interpretation, we develop an identifiability criterion which ensures the uniqueness of a solution. This criterion generalizes the work on l1 synthesis minimization tothe analysis case, block case and others.

De nouvelles applications émergent avec le développement de l’électronique souple comme des panneaux tactiles pliables, ou des capteurs de mouvement humain portables (wearable). Les technologies bien maîtrisées des jauges silicium sont mal adaptées à ces usages (faible élongation maximale, hautes températures de fabrication). Dans ce contexte, il est nécessaire de développer de nouveaux types de jauges. De nombreuses alternatives sont étudiées, qu’on peut diviser en deux catégories principales : les transducteurs nanoscopiques et les transducteurs composites. Dans ce travail, on étudie la possibilité d’utiliser une jonction tunnel MIM (Métal Isolant Métal) comme jauge de contrainte. Ce genre de dispositif est très peu étudié dans la littérature et la structure utilisée est généralement de type MIS (Métal Isolant Semi-conducteur). À chaque fois, la sensibilité du dispositif est expliquée par les propriétés du semi-conducteur (silicium). Les objectifs de cette thèse sont donc la compréhension des propriétés piézorésistives des jonctions MIM, l’optimisation de leur sensibilité et la fabrication d’un démonstrateur exploitant les technologies de la plastronique. Des jonctions de différentes natures (électrodes de différents métaux) sont fabriquées par évaporation et par ALD (Atomic Layer Deposition). La variation du courant en fonction de la contrainte est mesurée grâce à un banc de flexion. Le facteur de jauge associé est indépendant de la nature des électrodes mais varie fortement (de 40 à 75) en fonction du sens de polarisation de la jonction. Le facteur de jauge associé à la variation sous contrainte des paramètres géométriques (épaisseur et surface) est calculé mais reste inférieur à 13. Les phénomènes géométriques ne peuvent donc pas expliquer la sensibilité observée. L’étude de l’équation du courant Fowler Nordheim (identifié comme courant dominant dans nos jonctions) montre que cette sensibilité doit être associée à la variation sous contrainte de la hauteur de barrière aux interfaces métal/isolant, et/ou de la masse effective des électrons dans l’alumine. Des mesures de photoémission sont réalisées pour mesurer la hauteur de barrière des jonctions. À terme, cette méthode pourrait permettre de mesurer la variation sous contrainte, et donc de comprendre pleinement l’origine de la sensibilité des jonctions MIM. Pour finir, un démonstrateur intégrant des jauges MIM à effet tunnel (capteur de pression) est réalisé avec un substrat souple en polyimide rigidifié par une structure imprimée en 3D. Ce dispositif démontre la compatibilité des méthodes de fabrication des MIM avec les technologies souples et plastiques. / New applications are emerging with de development of flexible electronic like flexible touch panels and wearable movement sensors. The well mastered silicon technologies are ill adapted to these uses (low maximal elongation, high fabrication temperatures). In this context, it is necessary to develop new types of strain gauges. Numerous possibilities have been studied that can be divided in two main categories: nanosomic transducers and composite transducers. In this work, we study the possibility to use a MIM (Metal Insulator Metal) tunnel junction as strain gauge. This kind of structure is very unusual in the literature were the only similar article are based on MIS (Metal Insulator Semiconductor) junctions. The objectives of this thesis are thus the understanding of the piezorisistive properties of MIM structures, the optimisation of their sensitivity, and the realisation of a sensor prototype exploiting plastonic technologies.

Several standardized courses for Formula SAE (FSAE) testing are introduced and described with sufficient detail to be reproduced by any Formula SAE team. Basic analysis methods for the courses are given as well as explanations of how those analyses could be used. On-car data from the Global Formula Racing (GFR) SAE cars is used to verify the analysis methods, give estimates to unknown variables, and show the relevance of the standard testing courses. Using the courses and methods described in this paper should allow standardized comparison of FSAE car performance, as well as provide a method to verify simulations and evaluate changes in vehicle performance from tuning. Instrumentation of all suspension member forces with strain gauge load cells is shown to be an extremely powerful tool for measuring vehicle performance and quantifying vehicle dynamic characteristics. The design and implementation of strain gauge load cells is described in detail to provide a template for reproducing similar results in other vehicles. Data from the GFR 2011 FSAE car is used throughout the paper to: show the design process for making effective suspension member load cells, show the calibration processes necessary to ensure quality data is collected, illustrate the calculation of suspension corner forces, and show the effectiveness of measuring vehicle dynamic characteristics with this technique. Using the methods described in this paper should provide data that allows a more complete and thorough understanding of on-car vehicle dynamics. This data may be used to validate vehicle models. / Graduation date: 2012

The world is undergoing rapid changes and the future is uncertain. The changes are related to modification of the landscape due to human activities, such as large and small scale irrigation, afforestation and changes to the climate system. Understanding and predicting hydrologic change is one of the challenges facing hydrologists today. Part of this understanding can be developed from observed data, however, there often too few observations and those that are available are frequently affected by uncertainties. Hydrological models have become essential tools for understanding historical variations of catchment hydrology and for predicting future possible trends. However, most developing countries are faced with poor spatial distributions of rainfall and evaporation stations that provide the data used to force models, as well as stream flow gauging stations to provide the data for establishing models and for evaluating their success. Hydrological models are faced with a number of challenges which include poor input data (data quality and poorly quantified human activities on observed stream flow data), uncertainties associated with model complexity and structure, the methods used to quantify model parameters, together with the difficulties of understanding hydrological processes at the catchment or subbasin. Within hydrological modelling, there is currently a trend of dealing with equifinality through the evaluation of parameter identifiability and the quantification of uncertainty bands associated with the predictions of the model. Hydrological models should not only focus on reproducing the past behaviour of a basin, but also on evaluating the representativeness of the surface and subsurface model components and their ability to simulate reality for the correct reasons. Part of this modelling process therefore involves quantifying and including all the possible sources of uncertainty. Uncertainty analysis has become the standard approach to most hydrological modelling studies, but has yet to be effectively used in practical water resources assessment. This study applied a hydrological modelling approach for understanding the hydrology of a large Tanzanian drainage basin, the Great Ruaha River that has many areas that are ungauged and where the available data (climate, stream flow and existing water use) are subject to varying degrees of uncertainty. The Great Ruaha River (GRR) is an upstream tributary of the Rufiji River Basin within Tanzania and covers an area of 86 000 km2. The basin is drained by four main tributaries; the Upper Great Ruaha, the Kisigo, the Little Ruaha and the Lukosi. The majority of the runoff is generated from the Chunya escarpment, the Kipengere ranges and the Poroto Mountains. The runoff generated feeds the alluvial and seasonally flooded Usangu plains (including the Ihefu perennial swamp). The majority of the irrigation water use in the basin is located where headwater sub‐basins drain towards the Usangu plains. The overall objective was to establish uncertain but behavioural hydrological models that could be useful for future water resources assessments that are likely to include issues of land use change, changes in patterns of abstraction and water use, as well the possibility of change in future climates.