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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.
41

Simulační studie robotické linky pro obsluhu obráběcího stroje a realizaci dokončovacích operací / A simulation study of a robotic cell for production machine operation and realization of finishing operation

Kljajič, Marko January 2020 (has links)
The aim of the thesis is conceptual design of robotic workplace with its subsequent simulation. The current workplace for manufacturing and deburring parts for automotive industry is operated manually. The plan is overall automation and replacement of operators by robots. The thesis deals with the concept of layout of elements in the cell, and the procedure of their selection or design. Process simulation is performed in the Process Simulate software from Siemens. For the purposes of the work is used RCS module, which on the basis of dynamic conditions can calculate the cycle of production very close to the reality. The production cycle is compared to the current workplace. The work also deals with the economic evaluation of the proposed workplace.
42

Architecture à qualité de service pour systèmes satellites DVB-S/RCS dans un contexte NGN

Alphand, Olivier 07 December 2005 (has links) (PDF)
L'objet de cette thèse est de doter les réseaux satellites d'accès géostationnaires d'une architecture de QoS compatible avec l'infrastructure NGN (Next Generation Network) qui entend réaliser la convergence des réseaux et services de communication existants et à venir. Dans une première étape, nous établissons un modèle de QoS NGN s'inspirant principalement de l'évolution des architectures de QoS dans les réseaux IP. Dans une deuxième étape, nous démontrons que les réseaux satellites ne disposent pas, en l'état actuel, d'une architecture de QoS suffisamment mature pour assurer un accès large bande aux futurs services IP multimédias. Afin d'y remédier, nous spécifions une architecture de QoS NGN unifiée assurant une étroite collaboration entre les mécanismes de QoS déployés à différents niveaux de communication (Application, Session, Réseau et MAC). Elle assure à la fois une différenciation de la QoS adaptée aux besoins des différentes classes d'applications au niveau IP tout en optimisant l'utilisation des ressources satellites via des mécanismes de bande passante à la demande au niveau MAC. Deux solutions applicatives assurant la corrélation dynamique entre les applications et les services réseaux différenciés sont également spécifiées et implémentées. Enfin un émulateur satellite de niveau réseau a été implémenté et nous a permis d'évaluer les garanties de QoS offertes par notre architecture et de valider leur conformité avec les besoins d'applications multimédias réelles.
43

Coparticipación municipal de la provincia de Buenos Aires

Sotelo, Rodrigo 20 May 2010 (has links)
El objetivo del trabajo es estudiar una de las fuentes de financiamiento de los municipios de la Provincia de Buenos Aires: las transferencias del régimen de coparticipación municipal. Para ello se evalúan dos aspectos de dicho régimen: 1- el carácter devolutivo del régimen general (RG) y 2- el funcionamiento del régimen de coparticipación por salud (RCS). Para analizar el carácter devolutivo del RG se evalúa el grado de cercanía del ordenamiento de los partidos según su aporte al Producto Bruto Geográfico provincial y su participación en la distribución secundaria de la coparticipación mediante el RG. Para analizar el funcionamiento del RCS se comparan los recursos distribuidos por este mecanismo con lo gastado en la finalidad salud y con la demanda potencial de los servicios de salud municipales. Los principales resultados del trabajo indican que: 1. existe cierto grado de devolución en el RG; 2. el diseño actual del RCS ha generado y genera fuertes inequidades horizontales así como ineficiencias asignativas producto de inconsistencias en el diseño del régimen vigente.
44

Radarupptäckt av artilleriraketer

Humeur, Robert January 2012 (has links)
Denna rapport behandlar en radarsensors förmåga att upptäcka 107 mm raketerberoende på hur sensorn positioneras i förhållande till skyddsobjektet.Fältförsök, underrättelser och stridserfarenheter har visat att dessa raketer ärvanligt förekommande samt svåra att detektera med radarsensorer. En modell för hur räckviddsökning beror på olika sensorpositioner har skapats genom att använda dokument från USA och forna Sovjetunionen beskrivande ballistik tillsammans med teorier för hur räckvidd påverkas av radarmålarea (RCS) samten beskrivning av RCS tillhandahållen av FOI. Resultat från körningar iMATLAB visar att sensorpositioner inom 300 meter från skyddsobjektet ärfördelaktiga vid en skottvidd av 3000 meter. Som tumregel för att uppnå maximal sensorprestanda bör strävan vara att placera sensorn på ett avståndfrån skyddsobjektet understigande 10% av förväntad skottvidd.
45

Estudos sobre a modelagem e simulação de um reator snox®

CAMELO, Marteson Cristiano dos Santos 06 June 2016 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-05-24T12:54:55Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese mar 1.pdf: 2548372 bytes, checksum: e5acdc58a26dcd7f9102954cb7d402dc (MD5) / Made available in DSpace on 2017-05-24T12:54:55Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese mar 1.pdf: 2548372 bytes, checksum: e5acdc58a26dcd7f9102954cb7d402dc (MD5) Previous issue date: 2016-06-06 / Um dos principais problemas ambientais nos países industrializados está relacionado a liberação no meio ambiente de gases formadores de chuva ácida. A quantidade desses gases lançada para atmosfera é controlada pela legislação ambiental que vem se tornando cada vez mais restritiva. Vários são os processos aplicados a indústria capazes de remover esses contaminantes de correntes advindas de processos industriais. Dentre esses, destaca-se o processo SNOX® da Haldor Topsoe®, o qual é capaz de remover NOX e SOX de efluentes gasosos industriais, visando enquadrar a concentração desses gases dentro dos parâmetros exigidos pela legislação ambiental. A remoção desses gases é realizada por um reator constituído por dois leitos catalíticos, distintos, em série. O primeiro leito catalítico é constituído por um catalisador de estrutura monolítica, nesse ocorre a reação de redução do NOX. Enquanto que, o segundo leito é constituído por um catalisador em formato de anéis de Rashig, e nesse ocorre a oxidação do SO2. Neste trabalho foi modelado e simulado o comportamento dinâmico de um reator de abatimento de emissões atmosféricas nas condições operacionais similares a um reator de uma unidade SNOX®. Cada um dos leitos catalíticos que compõem o reator foi modelado e validado separadamente. No primeiro leito além da reação de redução do NO também considerou-se a reação de oxidação do SO2, esse modelo matemático foi simulado e avaliado nas condições operacionais apresentadas em Tronconni et al. (1998). No segundo leito catalítico do reator considerou-se apenas que a reação de oxidação do SO2 acontecia no leito, o modelo matemático do leito de oxidação foi simulado e avaliado nas condições operacionais apresentadas em Almqvist et al. (2008). Ambos os modelos apresentaram bom ajuste aos dados experimentais com erros entre 2 e 11%. Com isso, os dois modelos foram acoplados num código computacional e simulados nas condições operacionais do reator SNOX® mostrado em Schoubye e Jensen (2007). O primeiro leito catalítico teve um incremento na temperatura ao longo do reator de 9°C e a conversão de NO foi de 92%, a região de entrada do primeiro leito foi a região com maior quantidade de sítios catalíticos ocupados pela amônia. Já no segundo leito catalítico a conversão do SO2 foi de 96%. Como parte do estudo de modelagem e simulação do reator, técnicas de análise de sensibilidade global foram aplicadas, determinando-se o grau de dependência de parâmetros específicos sobre: as concentrações de NO, NH3 e SO3, no primeiro leito do reator, e as concentrações de SO2 e SO3 no segundo leito. Determinou-se que dentre os parâmetros avaliados o que teve maior influência sobre as concentrações de saída de ambos os leitos foi o comprimento do leito. A partir do modelo matemático desenvolvido neste trabalho também foram gerados dados para inferir as concentrações de NO e SO3 na saída do reator, que foi realizada através de redes neurais e máquinas de vetor de suporte. Verificou-se que a performance da estimação realizada pelas redes neurais se assemelha a das máquinas de vetor de suporte. / One of the main environmental problems in industrialized countries is related to release into the forming gas environment of acid rain. The amount of greenhouse gases released into the atmosphere is controlled by the environmental legislation, that is becoming increasingly restrictive. Several processes are applied to industry to remove these contaminants from currents resulting from industrial processes. Among these, there is the SNOX® Haldor Topsoe process, which is capable of removing NOx and SOx from industrial emissions, aiming to frame the concentration of these gases within the parameters required by environmental legislation. The removal of these gases is conducted by the process reactor consisting of two catalytic beds distinct in series. The first catalyst bed has a monolithic catalyst structure, in it occurs the reduction reaction of NOx. The second bed has a catalyst with shape of cylindrical rings, in this bed occurs the oxidation of SO2. In this work was modeled and simulated the dynamic behavior of atmospheric emissions abatement reactor in similar operating conditions to a reactor of a SNOX® unit. Each of the catalyst beds, that it make up the reactor, was modeled and validated separately. In the first bed was considered the reactions of reduction of NO and oxidation of SO2, this mathematical model was simulated and evaluated in the operating conditions presented in Tronconni et al. (1998). In the second catalytic bed was considered that only the reaction of oxidation SO2 occurred in the bed, the mathematical model of the oxidation bed was simulated and evaluated in operating conditions presented in Almqvist et al. (2008). Both models showed good fit to the experimental data with error between 2-11%. Thus, the two models had been written in computer code and simulated in reactor operating conditions SNOX® shown on Schoubye and Jensen (2007). The first catalyst bed had an increase in temperature along it of 9 ° C and the conversion of NO was 92%. In the first bed, the inlet region was the region with larger amount of catalytic sites occupied by ammonia. On the second catalytic bed, the SO2 conversion was 96,6%. As part of the modeling and simulation study for reactor the global sensitivity analysis techniques were applied aiming to determine the influence of some parameters over the concentrations of NO, NH3 and SO3 in the bed of catalytic reduction of NO and the concentration SO2 and SO3 in SO2 oxidation bed. From this study it was determined that among the evaluated parameters which it had the greatest influence on the output levels of the first reactor bed was the length of this bed. From the mathematical model developed in this paper we were also generated data to infer the concentrations of NO and SO3 in the reactor outlet, which was performed by neural networks and support vector machines. It was found that the performance of infer carried out by the neural network resembles to the performance of support vector machines.
46

Advancing Millimeter-Wave Vehicular Radar Test Targets for Automatic Emergency Braking (AEB) Sensor Evaluation

Belgiovane, Domenic John, Jr. January 2017 (has links)
No description available.
47

Magnetic Resonance Imaging of the Rat Retina

Bhagavatheeshwaran, Govind 16 April 2008 (has links)
The retina is a thin layer of tissue lining the back of the eye and is primarily responsible for sight in vertebrates. The neural retina has a distinct layered structure with three dense nuclear layers, separated by plexiform layers comprising of axons and dendrites, and a layer of photoreceptor segments. The retinal and choroidal vasculatures nourish the retina from either side, with an avascular layer comprised largely of photoreceptor cells. Diseases that directly affect the neural retina like retinal degeneration as well as those of vascular origin like diabetic retinopathy can lead to partial or total blindness. Early detection of these diseases can potentially pave the way for a timely intervention and improve patient prognosis. Current techniques of retinal imaging rely mainly on optical techniques, which have limited depth resolution and depend mainly on the clarity of visual pathway. Magnetic resonance imaging is a versatile tool that has long been used for anatomical and functional imaging in humans and animals, and can potentially be used for retinal imaging without the limitations of optical methods. The work reported in this thesis involves the development of high resolution magnetic resonance imaging techniques for anatomical and functional imaging of the retina in rats. The rats were anesthetized using isoflurane, mechanically ventilated and paralyzed using pancuronium bromide to reduce eye motion during retinal MRI. The retina was imaged using a small, single-turn surface coil placed directly over the eye. The several physiological parameters, like rectal temperature, fraction of inspired oxygen, end-tidal CO2, were continuously monitored in all rats. MRI parameters like T1, T2, and the apparent diffusion coefficient of water molecules were determined from the rat retina at high spatial resolution and found to be similar to those obtained from the brain at the same field strength. High-resolution MRI of the retina detected the three layers in wild-type rats, which were identified as the retinal vasculature, the avascular layer and the choroidal vasculature. Anatomical MRI performed 24 hours post intravitreal injection of MnCl2, an MRI contrast agent, revealed seven distinct layers within the retina. These layers were identified as the various nuclear and plexiform layers, the photoreceptor segment layer and the choroidal vasculature using Mn54Cl2 emulsion autoradiography. Blood-oxygenlevel dependent (BOLD) functional MRI (fMRI) revealed layer-specific vascular responses to hyperoxic and hypercapnic challenges. Relative blood volume of the retina calculated by using microcrystalline iron oxide nano-colloid, an intravascular contrast agent, revealed high blood-volume in the choroidal vasculature. Fractional changes to blood volume during systemic challenges revealed a higher degree of autoregulation in the retinal vasculature compared to the choroidal vasculature, corroborating the BOLD fMRI data. Finally, the retinal MRI techniques developed were applied to detect structural and vascular changes in a rat model of retinal dystrophy. We conclude that retinal MRI is a powerful investigative tool to resolve layer-specific structure and function in the retina and to probe for changes in retinal diseases. We expect the anatomical and functional retinal MRI techniques developed herein to contribute towards the early detection of diseases and longitudinal evaluation of treatment options without interference from overlying tissue or opacity of the visual pathway.
48

Contributions expérimentales originales en chambres réverbérantes à brassage de modes et en cavités surdimensionnées / Original experimental contributions in reverberation chambers and in oversized cavities

Soltane, Ayoub 17 December 2018 (has links)
La chambre réverbérante à brassage de modes (CRBM) est une cavité métallique fermée surdimensionnée, équipée d’un brasseur de modes. Le brassage de modes rend le champ électromagnétique homogène et isotrope à l’intérieur de la CRBM (dans son volume utile). Cette thèse illustre tout d’abord une nouvelle méthode pour évaluer les performances d’un brasseur de modes (via le spectre Doppler). Ensuite, elle présente une nouvelle méthode permettant de mesurer la surface équivalente radar (SER) d’un objet canonique en utilisant la technique de fenêtrage temporel ou time-gating. Enfin, elle présente une nouvelle méthode permettant de mesurer le diagramme de rayonnement d’une antenne dans une cavité surdimensionnée via la technique de time-gating. / The reverberation chamber (RC) is an oversized closed metal cavity, equipped with a mode-stirrer. The mode stirring makes the electromagnetic field homogeneous and isotropic inside the RC (in its useful volume). This thesis illustrates firstly a new method for evaluating the performance of a mode-stirrer (via the Doppler spectrum). Then, it presents a new method for measuring the radar cross section (RCS) of a canonical object using the time-gating technique. Finally, it presents a new method for measuring the antenna radiation pattern in an oversized cavity via the time-gating technique.
49

Adaptation de la couche transport des systèmes de communication hybrides satellite/terrestre

Tou, Ihsane 13 December 2012 (has links) (PDF)
Nos travaux de thèse ont pour objectif l'adaptation de la couche transport des systèmes de communications hybrides satellite/terrestre. Les réseaux satellites DVB-S2/RCS représente une solution alternative dans les zones reculés ou non couvertes par les réseaux filaires. Cependant, vu leur coût élevé et les caractéristiques qu'ils présentent, ils doivent être utilisés en complémentarité avec les solutions terrestres, constituants des réseaux intégrées ou hybrides (satellite/terrestre), en support du multiservice, avec ce que cela entraine en termes d'exigences liées aux nouveaux usages (accès généralisé et transparent). La première contribution consiste à l'analyse d'un système réel afin de caractériser le lien satellite. Cette démarche permet une éventuelle configuration d'un système émulé et s'avère le meilleur moyen pour bien paramétrer ce dernier. Par la suite, nous avons procédé à un ensemble de tests d'évaluation de plusieurs versions de TCP en utilisant l'émulateur SATEM. Vu les caractéristiques que représentent ces nouvelles versions de TCP, nous avons abouti à une proposition originale consistant à utiliser sur le segment satellite ces versions sans autre artifice architectural. Nous avons aussi proposé une solution qui permet d'améliorer le contrôle de congestion sur la voie aller DVB-S2 avec l'ACM pour les applications streaming, en utilisant le DCCP. Enfin, nous proposons une solution d'adaptation au niveau transport, qui s'avère efficace pour les handovers dans les réseaux hybrides satellites/terrestres et qui vient étayer nos résultats obtenus sur le segment satellite.
50

Etude d'un banc de caractérisation d'antennes intégrées miniatures aux fréquences millimétriques / Development of a test setup for miniature antennas for millimeter frequencies

Fu, Yan 18 July 2012 (has links)
Lors de cette thèse, on a développé un banc automatisé de relevé du diagramme de rayonnement particulièrement pour des antennes millimétriques avec faible directivité. On propose trois méthodes d’alimentation. La première méthode développée a été de concevoir une nouvelle sonde ayant un accès micro-coaxial de plus de 5cm afin de réduire la zone de masquage au minimum. Associée à une configuration de type flip-chip inversée, cette méthode a permis d’avoir une réduction de la zone de masquage de 80° à 20°. La deuxième méthode a été de concevoir une liaison souple par film souple de Kapton. Cette méthode présente l’avantage de placer une plus grande partie des connexions métalliques sous un plan de masse, mais nécessite une connexion optimale à la puce. Les résultats obtenus présentent une zone de masquage pratiquement inexistante, et sont conformes à l’état de l’art. La troisième méthode SER est basée sur la mesure de l’antenne sans placer de sondes ou de connecteurs spéciaux, mais en utilisant un système à charges connues. La simulation nous montre qu'il nous manque une dynamique par ces trois charges. / In this thesis, we designed and built a new 3D test bench, particularly for low-directivity integrated antennas at millimeter-wave frequencies. We proposed three feeding techniques for the antenna under test (AUT): a probe-fed technique, a flexible-transmission-line-fed technique and a radar-cross-section (RCS) method. The probe-fed method was developed with a customized probe, which involves an elongated (50 mm) coaxial line between the probe tip and the probe body, wherein the probe body is reversed (relative to the conventional measurement configuration) so it lies below the plane of the AUT. This method reduces the range of angles that are masked from 80° (for a conventional probe setup) to 20°. The second method was developed using a flexible transmission line with a modified flip-chip connection to the AUT. This method completely eliminates the masked zone. The third method characterizes the radiation pattern using a radar cross-section (RCS) method. This method requires neither a probe system nor connectors. However the simulation results demonstrate that there is insufficient variation in the ratio of received power to incident power as the load on the AUT is varied in order to make precise measurement with conventional measurement equipment.

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