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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.
131

Étude d'une source d'ions obtenue par extraction et accélération à partir d'une source plasma filaire

Gueroult, Renaud 19 September 2011 (has links) (PDF)
L'objet de ce travail consiste dans un premier temps en la modélisation d'une source plasma filaire en régime continu basse pression, puis, dans un second temps, en la caractérisation des propriétés d'une source d'ions développée sur la base de la source plasma préalablement étudiée. Un code particulaire permettant de modéliser le fonctionnement de la source plasma est ainsi développé, puis validé par comparaison avec les résultats d'une étude expérimentale. A la lueur des résultats de simulation, une analyse de la décharge en termes d'écoulement ionique de Child-Langmuir collisionnel en géométrie cylindrique est proposée, permettant alors d'interpréter la transition de mode comme une réorganisation naturelle de la décharge lorsque le courant de décharge excède un courant limite fonction de la tension de décharge, de la pression et de l'espace inter-électrodes. L'analyse de la fonction de distribution en énergie des ions impactant la cathode met par ailleurs en évidence la possibilité d'extraire un faisceau d'ions de faible dispersion en énergie autour de la tension de décharge, et ce sous réserve d'opérer la décharge dans son mode haute pression. Un prototype de source d'ions permettant l'extraction et l'accélération d'ions à partir de la source filaire est alors proposé. L'étude expérimentale d'un tel dispositif confirme le fait que l'adjonction d'un processus d'accélération se traduit par un simple décalage de la fonction de distribution en vitesse des ions d'une valeur correspondant à la tension d'accélération, mais ne l'élargit pas. Il est ainsi possible de produire des faisceaux d'ions de diverses espèces ioniques, d'énergie modulable (0-5 keV) et de dispersion en énergie limitée (~ 10 eV). Les courants de faisceau mesurés sont de quelques dizaines de micro-ampères, et la divergence d'un tel faisceau est de l'ordre du degré. Une modélisation numérique de cette source d'ions est finalement entreprise afin d'identifier de possibles optimisations du concept proposé.
132

Caractérisation prosodique et reconnaissance de la modalité déclarative de l'espagnol des Îles Canaries

Hernandez Diaz, Beatriz 09 November 2012 (has links) (PDF)
Notre recherche s'inscrit dans le projet AMPER (Atlas Multimédia Prosodique de l'Espace Roman) et elle a comme objectif principal celui d'offrir une caractérisation prosodique plus systématique de la modalité déclarative de l'espagnol parlée aux Îles Canaries. L'étude présente une double perspective : prosodique et dialectologique, car elle combine des variables strictement linguistiques (comme l'extension des syntagmes et leur combinaison accentuelle), en établissant des relations avec d'autres niveaux linguistiques comme le lexique et la syntaxe, mais aussi avec la phonétique segmentale, avec des variables sociolinguistiques (comme le sexe des informateurs, l'île d'origine, le milieu urbain ou rural et leur niveau d'études), qui nous permettent de vérifier que les informateurs constituent un groupe homogène, avec une intonation clairement représentative de la variété canarienne. Les résultats de l'analyse acoustique - vérifiés au niveau perceptif - démontrent que, effectivement, au-delà des coïncidences avec d'autres variétés, l'intonation de l'espagnol parlé aux Îles est parfaitement reconnaissable.
133

Respiratory Monitoring System Based on the Thoracic Expansion Measurement

Araujo Cespedes, Fabiola 01 January 2012 (has links)
The purpose of this reasearch was to develop a respiratory monitoring system using a reflective object sensor based belt to measure the thoracic expansion of a neonatal for future application at the medical center of the Universidad Evangelica Boliviana (UEB). This medical center, being founded by the UEB University, is dedicated to help and serve the poor and currently has no respiratory monitoring system. The methodology used was first to build and test the respiratory sensor belt and test the relationship between the blet expansion and the voltage generated. The, to incorporate the respiratory sensor belt in a system that would allow individual testing as well as group testing in a wireless network. The system was simulated using an expandable plastic container that was expanded and extracted periodically, registering the results in a MATLAB software. The system gave successful results and generated the frequency results of each cycle, average frequency and deviation frequency. The system demonstrated to be reliable and to have repeatable results.
134

Development Of A Pc Numerical System For High Voltage Sphere Gap Control

Kasap, Onur 01 June 2005 (has links) (PDF)
In this thesis, a high precision motion and position control system has been developed and applied to a high voltage sphere gap control and measurement system. The system is able to support up to 3-axes position and motion control. The control system includes a microcontroller card, three DC servo motor driver cards and a data storage unit. To provide communication between computer and motion control system, the Universal Serial Bus (USB) port is used. The microcontroller card is equipped with an USB interface and a PIC (Peripheral Interface Controllers) microcontroller. This microcontroller controls the dedicated motion control processors (LM629), on servo motor driver cards and read/write operations of data storage unit, which consists of a Multi Media Card.
135

Desenvolvimento de um sistema minimamente invasivo para monitorar a pressão intracraniana / Development of a minimally invasive system to monitor the intracranial pressure

Gustavo Henrique Frigieri Vilela 02 December 2010 (has links)
A pressão intracraniana (PIC) é um dos principais parâmetros neurológicos em animais e humanos. A PIC é uma função da relação entre o conteúdo da caixa craniana (parênquima cerebral, líquido cefalorraquiano e sangue) e o volume do crânio. O aumento da PIC (hipertensão intracraniana) pode acarretar graves efeitos fisiológicos ou até mesmo o óbito em pacientes que não receberem rapidamente os devidos cuidados, os quais incluem o monitoramento em tempo real da PIC. Todos os métodos de monitoramento da PIC atualmente utilizados são invasivos, ou seja, é necessário introduzir um sensor de pressão no sistema nervoso central, acarretando aos pacientes riscos de infecções e traumas decorrentes do método. Neste trabalho desenvolvemos um método minimamente invasivo de monitoramento da pressão intracraniana, que consiste na utilização de sensores de deformação do tipo strain gauge fixados sobre a calota craniana. Os sinais oriundos deste sensor foram amplificados, filtrados e enviados para um computador com software apropriado para análise e armazenamento dos dados. O trabalho aqui apresentado objetivou os testes "in vivo" do sistema, onde foi utilizada mais de uma centena de animais em diversos testes, sendo que em todos os casos os resultados foram satisfatórios, apontando a eficácia do método. / The intracranial pressure (ICP) is one of the most important neurological parameter in animals and humans. The ICP is a function of the relation between the contents of the skull (brain parenchyma, cerebrospinal fluid and blood) and the volume of the skull. The increase in ICP (intracranial hypertension) may cause serious physiological effects and death in patients that do not receive appropriate care quickly, which includes real-time monitoring of ICP. All monitoring methods currently used in ICP are invasive, ie requiring invasion of the central nervous system by a pressure sensor, causing infections and traumas risks to patients. In this work we present a new minimally invasive method to monitor the intracranial pressure. This uses strain gauge deformation sensors, externally glued on the skull. The signal from this sensor is amplified, filtered and sent to a computer with appropriate software for analysis and data storage. "In vitro" and "in vivo" experiments let to the following results: (1) Our minimally invasive system is capable of adequately monitoring the ICP. (2) The measurements are in real and online time providing excellent signal and stability. (3) Simultaneous comparison with invasive methods not only validated our results but showed increased performance. The equipment cost effective will allow the use of our system in the Public Health System, with a important social aspect of our contribution.
136

Konstruktion av Laborationskort med PIC-processorn / Construction of a laboration card with the PIC-processor

Wessman, Richard, Svensson, Jonny January 2002 (has links)
In this report you can get a complete instruction about how to build your own development system for the PIC-processor. This card will be used for laborations for the students at LITH-ITN. With this card you can send new assembler codes (new instructions) down to the microprocessor via the Serialport on your computer. Then the new instructions for the microprocessor will start to execute. We made a solder paste stencil at Campus Norrköping solder paste stencil laboratory. The software we made makes it possible to receive and transmit the new code to the board. The first part of our report contains some information about why we chose the components that we did. There are also some preferences about how these components are working. We also explain the architecture of the microprocessor because it is then easier to understand how to program it, which is explained later. We have made a guide for Microchips development kit MPLAB and some discussions about it. The components that we use are necessary to initiate and therefore we show in detail how this works. The software for transmitting the code from the computer to the card is presented and so is the code on the board that receives the transmitted data. When the board receives new code through the serial port it puts the code in the memory and start to execute it. To test our construction we made programs, which initiates and reads a temperature from one digital temperature sensor and one analog temperature sensor. We also got the opportunity to learn how the manufacturing of a solder paste stencil is proceeded. This proceed we have described in this report. All software is described in assembler but you can also make your programs in C. Additionally we have made a short investigation about how the C-compiler CCS is installed and used in MPLAB.
137

Návrh a výroba kamerového modulu / Design and implementation of camera module

Vokoun, Ondřej January 2012 (has links)
Cílem diplomové práce je navrhnout levný, avšak dostatečně výkonný a univerzální systém, schopný snímání a zpracování obrazu z digitální kamery. Další částí je návrh a implementace funkcí pro zpracování obrazu a komunikace s nadřazeným systémem.
138

Analysis of Hall effect thrusters using Hybrid PIC simulations and coupling to EP plume

Villegas Prados, David January 2020 (has links)
In the last 30 years, numerical models have been developed to properly analyze Hall eect thrusters (HET),leading to a bridge between analytical prediction/empirical intuition and experiments. For companies in thespace sector, these codes serve to much more than simply simulating the thruster, but it provides a fast, cheapand reliable tool for processes such as validation and verication procedures, as well as for technical developmentof the thruster. During the testing of the thruster, mostly measurements upstream from the thruster exhaustare obtained since the high density plasma inside the channel disturbs any measurement inside the channel. Thisresults in the company knowing about the output of the thruster performance, but having little knowledge aboutthe processes and behavior of the thruster itself. The purpose of this study is to help reduce the uncertainty,using existing software to eectively analyze and understand HETs. Because of the physical nature of theproblem, HET simulations follow a multi-scale approach where the thruster is divided into two regions: insidechannel/near-plume region and far-plume region. To study each zone dierent softwares are typically used.This thesis aims to nd a common ground between both software, coupling them and creating a line of analysisto follow when studying HETs.The present thesis will focus on the analysis of the famous SPT-100. The design of this work can be divided intotwo: an hybrid-PIC simulation with a software focusing on the inside channel and near-plume region, Hallis; andanother hybrid-PIC simulation regarding the plasma plume expansion performed with SPIS-EP. During thisproject both software were mastered. Hallis is investigated, emphasizing the empirical modelling of the electronanomalous transport inside the thruster and its consequences on the output results. A sensitivity analysis isperformed to obtain a good set of the empirical parameters that drive the overall performance of the thrusterand the plasma behavior. Once a good match persist between Hallis and nominal operating conditions, theoutput is used to construct the input injection distributions needed by the plasma expansion software (SPIS).Finally, the plasma plume is simulated and results are compared to in-house experimental data. In this way,one is able to control and understand the nal output directly from the behavior of the thruster. It is importantto mention that due to condentiality reasons, the testing data cannot be fully shown and sometimes only thetrend can be analyzed.As a results of the analysis, it is found that establishing the coupling between softwares is feasible, but Halliscode needs to include some characteristics to fully take advantage of its potential. It is determined that theion denition followed by Hallis is enough to perfectly dene the ion energy distribution as well as generalperformance parameters of the SPT-100 (thrust, ionization eciency, power...), but the poor electron modelgenerates some deviation in the results. SPIS simulations and comparison with testing data suggest that Hallisoutput is not enough to properly match the experimental measurements, especially regarding the ion angledistribution function. According to Hallis, such distribution is too narrow compared to the observed plasmaplume. This problem is found to be caused by the small simulation domain of Hallis. Hence, although couplingof the software is easy, more functionalities of Hallis would allow for a better study and more accurate results.
139

Targeting SR-mitochondria crosstalk to treat calcium-dependent arrhythmias in catecholaminergic polymorphic ventricular tachycardia

Deb, Arpita 08 August 2023 (has links) (PDF)
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a stress-induced arrhythmia, caused by genetic defects in sarcoplasmic reticulum (SR) Ca-release channel RyR2, or its accessory proteins. Our previous studies demonstrated that CPVT mitochondria can absorb RyR2-mediated aberrant Ca release (ACR) and behave as an efficient Ca buffer which is critical in mitigating harmful consequences of ACR. In this study, we test the hypothesis that modulating mitochondrial phosphate (Pi) transport or the tethering between SR-mitochondria, known as Mitochondria-associated-membrane (MAMs), impacts arrhythmogenesis in CPVT. We found that inhibiting mitochondrial Pi carrier (PiC) exacerbated cellular arrhythmias whereas overexpressing PiC in CPVT alleviated both cellular and in vivo arrhythmias. In parallel, disrupting MAMs exacerbated arrhythmogenesis in CPVT, but promoting MAMs by overexpressing mitofusin2 tethering protein reduced cellular arrhythmias. Our study provided both pharmacological and genetic evidence that directing more Ca to mitochondria by enhancing mitochondrial Pi transport or targeting MAMs could be promising therapeutic strategies to reduce CPVT arrhythmia.
140

Modelling and Optimisation of Relativistic Magnetron with Transparent Cathode : Applications for High-Power Microwaves / Modellering och Optimering av en Relativistisk Magnetron med Transparent Katod : Tillämpningar för Högeffektiv Mikrovågsstrålning

Sawert, David January 2023 (has links)
This thesis aimed to investigate the relativistic magnetron (RM), which is a high-power microwave (HPM) source. Since the RM can generate high-intensity microwave radiation, it can be used as a pulsed electromagnetic weapon to target electronic systems in different objects, such as drones, missiles, or vehicles. Other applications include electromagnetic compatibility (EMC) testing. In this thesis, a novel design of an RM with a transparent cathode configuration was investigated. This RM, referred to as the FOI-magnetron, was developed with the goal of generating the more advantageous TE11 mode of microwaves. This thesis starts with an in-depth theoretical exploration of the physics surrounding the RM, followed by a proof-of-concept study, where we compare our simulation results against published data. We then investigate the FOI-magnetron to determine if the transparent cathode configuration is more favourable than a solid cathode configuration. Particle-in-cell (PIC) simulations in MAGIC3D were used to study the RM, and extensive parameter studies were conducted for the FOI-magnetron to optimise its performance. The simulations revealed that the FOI-magnetron suffered from leakage currents. Moreover, parameter studies of the FOI-magnetron with transparent cathode demonstrated favourable TE11-mode emission of microwaves with a peak output power reaching 590 MW after 15 ns, having a frequency of 2.56 GHz, and an efficiency of 37%. Comparisons between thetransparent and solid cathode for the FOI-magnetron showed a slightly lower output power and efficiency for the transparent cathode, with minimal difference in the rise time of microwaves. Additionally, the transparent cathode exhibits a higher overall impedance and leakage currents. On the other hand, a lower back-current density on the transparent cathode and emitter was shown, resulting in less damage to the material. In this study, we found that we could reduce leakage currents by extending the interaction region without impacting the performance of the FOI-magnetron. Also, the frequency was shown to change with either a shorter emitter or a longer interaction region, allowing for frequency control. Lastly, a modified design of an RM with a semitransparent cathode showed a promisingly high efficiency of 46% with an output power of 600 MW. This design utilised endcaps, which are useful for significantly reducing leakage currents

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