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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A New Approach to Impacting the Construction Industry

January 2017 (has links)
abstract: Construction industry performance (schedule, budget, and customer satisfaction) has not improved over the last 20 years. This investigation proposes that academic/industry research using actual project data may have more impact on improving industry performance than traditional survey-based research. The authors utilize the CIB and CIB W117 platforms to proliferate the concept of academic/industry test results to increase the impact on the construction industry. The authors propose to use the existing journal and then share the journal papers on an online platform (ResearchGate.net) ensuring a faster proliferation of the key academic/industry test results into the academic research community. The mechanism of the academic/industry test results will have more of an impact on industry practices than the traditional publication systems, which concentrate on literature reviews and surveys to collect industry opinions and analyze the information to change industry practices. The proliferation of industry research results will create transparency in the construction industry and the academic research community. / Dissertation/Thesis / Masters Thesis Construction Management 2017
2

Conception et réalisation de micro-capteurs de pression pour l’instrumentation d’interface à retour d’effort / Pressure micro-sensor conception and fabrication for force feedback interfaces instrumentation

Nazeer, Sébastien 02 March 2012 (has links)
Ce travail de thèse présente la conception et la réalisation d’un capteur de pression 3D flexible pouvant être intégré dans un gant ou sur un outil de chirurgie pour qualifier et quantifier les forces de préhension notamment sous contraintes normales et de cisaillement. Un état de l’art présente d’abord les technologies se prêtant à cette application. Puis, le choix est porté sur la conception et le dimensionnement à partir de la loi de Hooke, d’un capteur matriciel capacitif tri-axe de 8 x 8 x 3 cellules/cm² à partir d’un diélectrique flexible de faible module d’Young autour de 1 MPa. Les cellules conçues ont une capacité nominale voisine de 0,5 pF. Une variation de 30% est attendue à une force maximale envisagée de 100 N/cm². La dynamique visée est de 1 à 1000. Elle correspondant à une résolution de 0,15 fF ou 100 mN/cm². La fabrication du capteur souple est abordée en prenant en compte la caractérisation des matériaux support, notamment le Kapton, dans un flux de microfabrication. Les problèmes de métallisation et d’adhérence d’électrodes sur PDMS conduisent au développement d’un procédé basé sur la technologie de transfert de film adapté aux électrodes enfouies dans le PDMS. Des résultats de simulation sous ANSYS valident le principe physique exploité. Ils sont confirmés par des mesures électriques statiques et en charge du capteur tactile pour des forces de 10 mN à 20 N. / This PhD work presents the design and realization of a 3D flexible force sensor that can be integrated in surgical gloves or tools to qualify and quantify the grip forces including normal and shear stress. A state of the art first presents the suitable technologies for this application. Then, the choice is focused on the design and dimensioning, using Hooke’s law, of a capacitive tri-axis sensor of 8 x 8 x 3 cells/cm² matrix from a flexible dielectric of low Young’s modulus around 1 MPa. Designed cells have a nearby nominal capacitance of 0.5 pF. A variation of 30% is expected at maximum force range of 100 N/cm². The aimed dynamic is 1 to 1000. It corresponds to a resolution of 0.15 fF or 100 mN/cm². The flexible sensor fabrication is tackled by taking into account the characterization of support materials, notably the Kapton, in a stream of microfabrication. Metallization and adhesion of electrodes on PDMS problems lead to the development of a process based on film transfer technology adapted to electrodes buried in PDMS. On the basis of ANSYS simulations, the operating physical principle is validated. They are confirmed by static and in charge electrical measurements of the tactile sensor for forces ranging from 10 mN to 20 N.
3

Multi-Harmonic Broadband Measurement with an Large-Signal Network Analyzer

Youngseo, Ko 24 August 2010 (has links)
No description available.
4

Structuration du silicium par laser femtoseconde : application au photovoltaïque

Torres, Rémi 12 July 2011 (has links)
Il a été montré récemment (Mazur et al, Harvard University) qu'un moyen simple d'améliorer le rendement des cellules solaires photovoltaïques actuelles pouvait être obtenu en irradiant la structure du silicium avec des impulsions laser femtoseconde en présence d'un gaz sulfuré (SF6). Cette irradiation entraîne la formation de micro-structures érigées (spikes) sur la surface. Celle ci devient ainsi fortement absorbante au rayonnement solaire (black silicon). Le travail effectué durant cette thèse a porté sur plusieurs points. Dans un premier temps une étude complète a été menée sur les différents paramètres expérimentaux permettant la création de ces micro-structures à la surface du silicium. Parallèlement, des séries d'expériences ont été menées pour permettre la compréhension des mécanismes physiques entraînant leur formation. Par la suite, les surfaces de silicium micro-structurées ont été caractérisées optiquement. Les résultats obtenus permettent d'avoir une absorption de 96 % du silicium dans les spectre UV et visible. Des cellules solaires complètes ont été réalisées afin d'en caractériser électriquement les performances. / It was shown recently (Mazur et al, Harvard University) a simple way to improve the performance of photovoltaic solar cells could be obtained by irradiating the surface of silicon with femtosecond laser pulses in a sulfide gas atmoshere (SF6). This irradiation causes the formation of micro-structures (spikes) on the surface becomes highly absorbent to solar radiation (black silicon). The work done during this thesis focused on several points. Initially a comprehensive study has been conducted on different experimental setting allowing the creation of these micro-structure on the surface of silicon. Parallel series of experiments were conducted to help understand the physical mechanism leading to their formation. Subsequently, the surfaces of silicon micro-structured were characterized optically. The results obtained allow to have an absorption of 96% silicon in the UV and visible. Complete solar cells were made in order to electrically characterized perform.
5

Grafické uživatelské rozhraní pro senzorické systémy / Graphical user interface for sensing systems

Dejdar, Petr January 2018 (has links)
Master thesis is focused on creating graphical user interface for the sensorical system based on Phase-OTDR. Theoretical part describes optical fibers, explains the principle of Bragg gratings, their production and their use in sensors. Methods of optical fiber attenuation and phase OTDR measurement are also described. Other part is focused on LabVIEW programming software and utilization of sensorical system and its components. Practical part deals with the user interface itself, which consists of two tabs. The first tab is designed for evaluation and display of measured data. The second tab is used to control and set up system components. Both of these tabs are further subdivided into other subtabs. Regarding the conclusion, further development of the program and options of hardware replacement for improving this sensorical system in the future will be discussed.
6

Enhancing Internet Security and Mobility with Host Identity Protocol: Integration, Testing, and Optimization : Simulation of HIP-VPLS using Mininet / Förbättring av säkerhet och rörlighet på internet genom Host Identity Protocol: integration, testning  och optimering

Christensson, Martin, De Paz, Edwin January 2024 (has links)
This project aims to enhance the capabilities of the Host Identity Protocol version 2 (HIPv2) within the Mininet network emulator and PyHIP framework. The objectives include integrating HIPv2 into Mininet to facilitate testing of HIPv2 environments and optimizing PyHIP for real-world applications. Integration with Mininet involves running the HIP daemon within a virtual host environment and ensuring successful ping replies between HIP-enabled Mininet hosts. Optimization efforts focus on potentially changing cryptographic algorithms. These enhancements aim to improve the testing and practical usability of HIPv2 in network emulation. The tests conducted for this thesis involved only two hosts, which limits the comprehensiveness regarding scalability and performance in larger network setups. While the initial findings are promising, a more extensive evaluation with varied scenarios and additional hosts is critical to fully grasp the system's capabilities. Regarding performance of the unmodified version, tests reveal that TCP window sizes ranging from 128,000 to 225,000 bytes and buffer settings at 3,000 $bytes$ were optimal for optimizing throughput. The last objective of throughput optimization, transitioning from PyCryptoDome to the cryptography library boosts throughput by approximately 20 Mbits/s, reaching up to 59 Mbits/s. Furthermore, it is important to acknowledge that modifications were not extended to the symmetric cryptography libraries, like AES, which could potentially greatly influence system throughput. Therefore, we recommend to further extend these modifications to validate throughput improvements across all modified cryptography algorithms. Depending solely on a single high-performing setup may mislead the assessment of the changes, as various iPerf3 test combinations could yield different outcomes. Thus, it is essential to recognize that these limitations may impact the credibility of the findings.
7

Kvinnliga lärares psykosociala arbetsmiljö : En kvantitativ tvärsnittsstudie om den självupplevda psykosociala arbetsmiljön, ur ett salutogent perspektiv / Female teachers psychosocial work environment : A quantitative cross-sectional study about the self-reported psychosocial work environment in a salutogenic perspective

Pettersson, Julia, Adolfsson, Ida January 2019 (has links)
Kvinnliga lärare upplever sitt arbete som meningsfullt samtidigt som de utsätts för tidspress, vilket har en negativ inverkan på deras psykosociala arbetsmiljö och hälsa. Syftet med denna studie var att beskriva den självupplevda psykosociala arbetsmiljön hos kvinnliga lärare ur ett salutogent perspektiv. En tvärsnittsstudie enligt en kvantitativ design gjordes på 43 kvinnliga lärare på tre olika skolor med hjälp av instrumentet Work Experience Measurment Scale (WEMS). Kompletterande frågor om ålder och år av yrkeserfarenhet tillfördes för att undersöka eventuellt samband. Resultatet visade att det inte finns något statistiskt signifikant samband mellan ålder eller år av yrkeserfarenhet i hur deltagarna upplever sin psykosociala arbetsmiljö. För att beskriva kvinnliga lärares psykosociala arbetsmiljö ur ett salutogent perspektiv användes främst modellen “känsla av sammanhang” (KASAM). Deltagarna har starkt KASAM vad det gäller meningsfullhet men svagare KASAM i hanterbarhet och begriplighet. Slutsatsen för studien visar på att kvinnliga lärare upplever sitt arbete som meningsfullt vilket påverkar den psykosociala arbetsmiljön positivt. Samtidigt utsätts de för tidspress, vilket har en negativ inverkan på deras psykosociala arbetsmiljö. / Female teachers experiencing their work meaningful at the same time the work expose them for time pressure, which can have a negative impact on the health. The aim of this study was to describe self-perceived psychosocial work environment for female teachers in a salutogenic approach. A cross-sectional study with a quantitative design with 43 female teachers on three different schools was preformed, using the instrument Work Experience Measurement Scale (WEMS). Additional questions about age and years of work experience added to explore any relationship. The result show that there was no statistic significant relationship between age or years of work experience in how the participants experiencing their psychosocial work environment. To describe female teachers psychosocial work environment in a salutogenic approach has uppermost the model “Sense of coherence” (SOC) been used. The participants have a strong SOC regarding meaningfulness, but weaker SOC regarding manageability and comprehensibility. The conclusion of this study show that female teachers experience their work meaningful, which affect the psychosocial work environment positive, at the same time they are exposed for time pressure, which affect the psychosocial work environment negative.
8

Quantification 3D d’une surface dynamique par lumière structurée en impulsion nanoseconde. Application à la physique des chocs, du millimètre au décimètre / 3D measurement of a dynamic surface by structured light in nanosecond regime. Application to shock physics, from millimeters to decimeters

Frugier, Pierre Antoine 29 June 2015 (has links)
La technique de reconstruction de forme par lumière structurée (ou projection de motifs) permet d’acquérir la topographie d’une surface objet avec une précision et un échantillonnage de points dense, de manière strictement non invasive. Pour ces raisons, elle fait depuis plusieurs années l’objet d’un fort intérêt. Les travaux présentés ici ont pour objectif d’adapter cette technique aux conditions sévères des expériences de physique des chocs : aspect monocoup, grande brièveté des phénomènes, diversité des échelles d’observation (de quelques millimètres au décimètre). Pour répondre à ces exigences, nous proposons de réaliser un dispositif autour d’un système d’imagerie rapide par éclairage laser nanoseconde, présentant des performances éprouvées et bien adaptées. La première partie des travaux s’intéresse à analyser les phénomènes prépondérants pour la qualité des images. Nous montrons quels sont les contributeurs principaux à la dégradation des signaux, et une technique efficace de lissage du speckle par fibrage est présentée. La deuxième partie donne une formulation projective de la reconstruction de forme ; celle-ci est rigoureuse, ne nécessitant pas de travailler dans l’approximation de faible perspective, ou de contraindre la géométrie de l’instrument. Un protocole d’étalonnage étendant la technique DLT (Direct Linear Transformation) aux systèmes à lumière structurée est proposé. Le modèle permet aussi, pour une expérience donnée, de prédire les performances de l’instrument par l’évaluation a priori des incertitudes de reconstruction. Nous montrons comment elles dépendent des paramètres du positionnement des sous-ensembles et de la forme-même de l’objet. Une démarche d’optimisation de la configuration de l’instrument pour une reconstruction donnée est introduite. La profondeur de champ limitant le champ objet minimal observable, la troisième partie propose de l’étendre par codage pupillaire : une démarche de conception originale est exposée. L’optimisation des composants est réalisée par algorithme génétique, sur la base de critères et de métriques définis dans l’espace de Fourier. Afin d’illustrer les performances de cette approche, un masque binaire annulaire a été conçu, réalisé et testé expérimentalement. Il corrige des défauts de mise au point très significatifs (Ψ≥±40 radians) sans impératif de filtrage de l’image. Nous montrons aussi que ce procédé donne accès à des composants tolérant des défauts de mise au point extrêmes (Ψ≈±100 radians , après filtrage). La dernière partie présente une validation expérimentale de l’instrument dans différents régimes, et à différentes échelles. Il a notamment été mis en œuvre sur l’installation LULI2000, où il a permis de mesurer dynamiquement la déformation et la fragmentation d’un matériau à base de carbone (champs millimétriques). Nous présentons également les mesures obtenues sous sollicitation pyrotechnique sur un revêtement de cuivre cylindrique de dimensions décimétriques. L’apparition et la croissance rapide de déformations radiales submillimétriques est mesurée à la surface du revêtement. / A Structured Light System (SLS) is an efficient means to measure a surface topography, as it features both high accuracy and dense spatial sampling in a strict non-invasive way. For these reasons, it became in the past years a technique of reference. The aim of the PhD is to bring this technique to the field of shock physics. Experiments involving shocks are indeed very specific: they only allow single-shot acquisition of extremely short phenomena occurring under a large range of spatial extensions (from a few mm to decimeters). In order to address these difficulties, we have envisioned the use of a well-known high-speed technique: pulsed laser illumination. The first part of the work deals with the evaluation of the key-parameters that have to be taken into account if one wants to get sharp acquisitions. The extensive study demonstrates that speckle effect and depth of field limitation are of particular importance. In this part, we provide an effective way to smooth speckle in nanosecond regime, leaving 14% of residual contrast. Second part introduces an original projective formulation for object-points reconstruction. This geometric approach is rigorous; it doesn’t involve any weak-perspective assumptions or geometric constraints (like camera-projector crossing of optical axis in object space). From this formulation, a calibration procedure is derived; we demonstrate that calibrating any structured-light system can be done by extending the Direct Linear Transformation (DLT) photogrammetric approach to SLS. Finally, we demonstrate that reconstruction uncertainties can be derived from the proposed model in an a priori manner; the accuracy of the reconstruction depends both on the configuration of the instrument and on the object shape itself. We finally introduce a procedure for optimizing the configuration of the instrument in order to lower the uncertainties for a given object. Since depth of field puts a limitation on the lowest measurable field extension, the third part focuses on extending it through pupil coding. We present an original way of designing phase components, based on criteria and metrics defined in Fourier space. The design of a binary annular phase mask is exhibited theoretically and experimentally. This one tolerates a defocus as high as Ψ≥±40 radians, without the need for image processing. We also demonstrate that masks designed with our method can restore extremely high defoci (Ψ≈±100 radians) after processing, hence extending depth of focus by amounts unseen yet. Finally, the fourth part exhibits experimental measurements obtained with the setup in different high-speed regimes and for different scales. It was embedded on LULI2000 high energy laser facility, and allowed measurements of the deformation and dynamic fragmentation of a sample of carbon. Finally, sub-millimetric deformations measured in ultra-high speed regime, on a cylinder of copper under pyrotechnic solicitation are presented.

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