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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

Development of a Short Range Tracking System using an Inertial Measurement Unit

Shackelford, James Casey 09 December 2011 (has links)
Inertial measurement units, or IMUs, serve as effective tracking devices when used in sophisticated aerospace control and navigational systems. This tracking potential, coupled with ever advancing technology that permits IMUs to become smaller and more compact, is allowing IMUs to gain popularity in a many areas of research beyond the areas of aerospace. Using an IMU based on microelectromechanical (MEMS) technology, this document investigates an IMU’s ability to track complex, short range motions such as golf swings. To prepare the IMU, an accurate, yet quick, calibration procedure is proposed and illustrated to show the tools and equipment necessary for this approach. Once calibrated, experimental results from static and dynamic tests are compared to corresponding analytical results to help comprehend and confirm the IMU readings. The IMU is then applied to a series of short range motions for reliability and performance testing.
2

Simulation numérique de modèles cinétiques réduits pour l'étude de la dynamique des plasmas de fusion par confinement magnétique / Numerical simulation of reduced kinetic models for the study of magnetically confined fusion plasmas

Coulette, David 06 December 2013 (has links)
Ce travail de recherche s'inscrit dans la problématique de la compréhension des phénomènes de transport turbulent de l'énergie et des particules au sein des plasmas de coeur des machines de fusion thermonucléaire par confinement magnétique. L'instabilité dite de gradient de température ionique, considérée comme une des sources majeures de transport turbulent, y est étudiée au moyen d'un modèle gyrocinétique. L'originalité de ce travail consiste en l'utilisation d'un modèle réduit, dit "Multi-Water-Bag", qui permet de réduire la dimension du problème tout en préservant les effets cinétiques. Ce modèle est développé dans deux types de géométries de champ de confinement. En géométrie cylindrique, l'évolution de l'instabilité est analysée au travers de trois modèles dynamiques : linéaire, quasi-linéaire et non-linéaire. L'analyse de stabilité linéaire permet d'obtenir les caractéristiques spectrales et géométriques de l'instabilité à partir d'une situation d'équilibre instable. Dans un deuxième temps, la confrontation par le biais de simulations numériques trois modèles dynamiques permet l'examen du développement de la turbulence, ainsi que les premières étapes de la saturation de l'instabilité. En géométrie torique, une analyse linéaire de stabilité est effectuée au moyen de deux méthodes, respectivement par intégration en temps et analyse spectrale, pour obtenir les caractéristiques des modes les plus instables. Pour chacune des géométries envisagées, les diverses méthodes numériques implémentées sont décrites et leurs performances évaluées. Une attention particulière est portée tout au long de ce travail à la mise en balance des coûts et bénéfices de la réduction Multi-Water-Bag / The research exposed therein is developed in the context of the study of turbulent energy and particle transport phenomena occuring in magnetically confined fusion plasmas. A study of the ion temperature gradient instability, one of the main sources of such turbulent transport, is carried out using a gyrokinetic model. The main originality of this work lies in the use of a reduced model, the so-called Multi-Water-Bag model, which allows to reduce the problem dimension while preserving kinetic effects. The model is developed in two types of confinement field geometries. In cylindrical geometry, the growth of the instability is analysed by the mean of three dynamical models : linear, quasi-linear and non-linear. Starting from a given unstable stationary state, linear stability analysis allows one to obtain spectral and geometrical characteristics of the instability. In a second phase, comparing results of numerical simulations implementing the three dynamical models, the growth of turbulence is analysed as well as the first stages of non-linear saturation of the instability. In toroidal geometry, a linear stability analysis is performed. Two different methods, time-based and spectral, were implemented in order to obtain the spectral and geometrical characteristics of the most unstable modes. In both field geometries encompassed by this research, the numerical methods used to obtain the results are described and their performances analyzed. Throughout the work, particular care is given to the balance between the benefits and costs of the Multi-Water-Bag reduction
3

Experimental study of density fluctuations in the STOR-M tokamak by small-angle microwave scattering

Livingstone, Stephen 27 January 2006
Density fluctuations in high temperature fusion plasmas have been a central challenge to the development of fusion power. They are the cause of excessive anomalous losses from the plasma and are still not fully understood. A microwave scattering experiment is performed on the Saskatchewan Torus-Modified (STOR-M) tokamak for the first time to study these density fluctuations with wave-numbers in the range <b><i>k</i></b> = 5 /cm to 10 /cm. The fluctuations are found to follow <i>k¦Ñ<sub>s</sub></i> scaling consistent with ion drift waves; signatures of the electron temperature gradient (ETG) mode connected with anomalous electron losses are not detected. The fluctuation level in the STOR-M is measured to be <i>n<sub>tilda</sub>/n</i> ¡Ö 0.1 at a mean perpendicular wave-number of <b><i>k</b><sub>perp</sub></b></i> ¡Ö 7 /cm and is reported for the first time. The fluctuation levels are inversely proportional to the energy confinement time suggesting that these fluctuations are driving anomalous particle and energy losses from the STOR-M. The system is now fully operational and this work paves the way for future experiments with this equipment.
4

Experimental study of density fluctuations in the STOR-M tokamak by small-angle microwave scattering

Livingstone, Stephen 27 January 2006 (has links)
Density fluctuations in high temperature fusion plasmas have been a central challenge to the development of fusion power. They are the cause of excessive anomalous losses from the plasma and are still not fully understood. A microwave scattering experiment is performed on the Saskatchewan Torus-Modified (STOR-M) tokamak for the first time to study these density fluctuations with wave-numbers in the range <b><i>k</i></b> = 5 /cm to 10 /cm. The fluctuations are found to follow <i>k¦Ñ<sub>s</sub></i> scaling consistent with ion drift waves; signatures of the electron temperature gradient (ETG) mode connected with anomalous electron losses are not detected. The fluctuation level in the STOR-M is measured to be <i>n<sub>tilda</sub>/n</i> ¡Ö 0.1 at a mean perpendicular wave-number of <b><i>k</b><sub>perp</sub></b></i> ¡Ö 7 /cm and is reported for the first time. The fluctuation levels are inversely proportional to the energy confinement time suggesting that these fluctuations are driving anomalous particle and energy losses from the STOR-M. The system is now fully operational and this work paves the way for future experiments with this equipment.
5

Adoção e implantação da NBC TG 1000 – Contabilidade para pequenas e médias empresas: um estudo nas empresas de serviços contábeis de Pernambuco

Granha, Marco Antonio 30 April 2014 (has links)
Submitted by Suethene Souza (suethene.souza@ufpe.br) on 2015-03-09T17:30:33Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Marco Antonio Granha.pdf: 1263356 bytes, checksum: 9dc72d1fa8943f95af039a3ad5c365bd (MD5) / Made available in DSpace on 2015-03-09T17:30:33Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Marco Antonio Granha.pdf: 1263356 bytes, checksum: 9dc72d1fa8943f95af039a3ad5c365bd (MD5) Previous issue date: 2014-04-30 / O presente estudo teve como objetivo explicar como as empresas de serviços contábeis se adaptaram a NBC TG 1000 – Contabilidade para Pequenas e Médias Empresas para a preparação, elaboração e divulgação das demonstrações contábeis de seus clientes. Para alcançar esse objetivo, a pesquisa utilizou uma abordagem de métodos misto sequencial, sendo inicialmente aplicado um questionário de pesquisa para as 148 empresas de serviços contábeis associadas ao SESCAP-PE obtendo 35 respostas representando a etapa quantitativa do estudo. Em seguida, entrevistas semiestruturadas baseadas em um roteiro elaborado a partir dos resultados da etapa inicial, foram realizadas com 8 sócios de 7 empresas de serviços contábeis de reconhecida experiência e competência técnica, representando a etapa qualitativa do estudo. Os resultados da etapa inicial da pesquisa evidenciaram que a maioria das empresas pesquisadas não adotam plenamente ou não conhecem a norma. Na segunda etapa da pesquisa, onde se buscou o aprofundamento das questões apontadas na etapa inicial, os resultados revelaram que a adoção da NBC TG 1000 pelas empresas de serviços contábeis ocorreu de forma parcial, sendo utilizadas apenas as seções relativas a elaboração das demonstrações contábeis. Os principais fatores que dificultaram a adoção plena da norma evidenciados pela pesquisa foram: a complexidade do texto do pronunciamento e o prazo considerado muito curto entre a divulgação e sua obrigatoriedade de adoção, a necessidade de cumprimento das exigências fiscais, o conhecimento ainda em fase de consolidação dos profissionais da contabilidade, a falta de interesse e conhecimento dos clientes em relação a importância das demonstrações contábeis e a resistência para entrega das informações e documentações em tempo hábil para o registro tempestivo das transações. Embora os respondentes tenham adotado de forma parcial a norma, todos consideram positivo o processo de convergência ao padrão internacional de contabilidade.
6

Modern Forms of an Ancient Art: A Selection of Contemporary Fanfares for Multiple Trumpets Demonstrating Evolutionary Processes in the Fanfare Form

Florek, Paul J. 05 1900 (has links)
The pieces discussed throughout this dissertation provide evidence of the evolution of the fanfare and the ability of the fanfare, as a form, to accept modern compositional techniques. While Britten’s Fanfare for St. Edmundsbury maintains the harmonic series, it does so by choice rather than by the necessity in earlier music played by the baroque trumpet. Stravinsky’s Fanfare from Agon applies set theory, modal harmonies, and open chords to blend modern techniques with medieval sounds. Satie’s Sonnerie makes use of counterpoint and a rather unusual, new characteristic for fanfares, soft dynamics. Ginastera’s Fanfare for Four Trumpets in C utilizes atonality and jazz harmonies while Stravinsky’s Fanfare for a New Theatre strictly coheres to twelve-tone serialism. McTee’s Fanfare for Trumpets applies half-step dissonance and ostinato patterns while Tower’s Fanfare for the Uncommon Woman demonstrates a multi-section work with chromaticism and tritones. By applying modern compositional techniques to an older, abstract form, composers have maintained the original aesthetic while allowing for fanfares to be used as concert music. This document adds to the limited body of scholarly writing on modern fanfares.
7

Le modèle « water bag » appliqué aux équations cinétiques des plasmas de Tokamak / Water bag modelling of kinetic plasmas in Tokamak

Morel, Pierre 04 July 2008 (has links)
Ce travail a porté sur l'étude des instabilités de gradient de température ioniques (ITG) en géométrie cylindrique, le champ magnétique étant supposé constant et dirigé selon l'axe du cylindre. Une fonction de distribution discrète en forme de marche d'escalier est utilisée pour décrire la direction de vitesse parallèle au champ magnétique. L'équation de Vlasov se résume à un système de type multi fluides couplés par l'équation de quasi neutralité. Chaque fluide est décrit par un système fermé d'équations (continuité, Euler et fermeture adiabatique), caractéristiques d'un fluide incompressible, d'où la dénomination de sac d'eau ou "water bag". Le recours à cette description water bag est particulièrement intéressant dans le cas de problèmes à une seule dimension en vitesse. Ainsi, dans le cas des plasmas fortement magnétisés, un modèle water bag peut se combiner avantageusement aux modèles dits girocinétiques. Les paramètres associés a la représentation water bag ont pu être identifiés et reliés aux grandeurs macroscopiques par le biais d'une méthode originale d'équivalence au sens des moments. L'analyse water bag des ITG a permis de valider le modèle et les méthodes choisies. Ce travail a également permis de montrer que le concept de water bag peut sans problème prendre en compte des effets variés comme ceux liés a l'introduction d?un rayon de Larmor fini, tout comme à la description d'un plasma composé de plusieurs espèces d'ions. / A drift-kinetic model in cylindrical geometry has been used to study Ion Temperature Gradients (ITG). The cylindrical plasma is considered as a limit case of a stretched torus. The magnetic field is assumed uniform and constant; it is directed along the axis of the column. A discrete distribution function f taking the form of a multi-step like function is used in place of the continuous distribution function along the parallel velocity direction. With respect to the properties of the Heaviside?s distribution, the Vlasov equation is reduced to a system of fluids coupled by the electromagnetic fields. This model is well suited mainly for problems involving a phase space with one velocity component. In the case of magnetized plasmas it gives an alternative way to study turbulence thanks to the gyro-average whose allows reducing the 3D velocity space into a 1D space. Parameters introduced by the water bag formalism have been linked to physical quantities by an original method of moment-sense equivalence. In the linear approximation, the water bag study of the ITG instability allows an interesting comparison with some well-known analytical results. The water-bag concept is not affected by taking into account Finite Larmor Radius effects. It well describes the case of multi-species plasma
8

Wave Propagation and Scattering in Communication, Microwave Systems and Navigation, WFMN09 / Wellenausbreitung und Streuung in Funk- Mikrowellensystemen und Navigation, WFMN09

01 February 2011 (has links) (PDF)
The ITG section 7.5 "Wellenausbreitung" within the VDE (German Association for Electrical, Electronic & Information Technologies) organised a conference on Wave Propagation in Communication, Microwave Systems and Navigation which was held during 25th - 27th of November 2009 in Chemnitz, Germany. The conference philosophy is to emphasize the commonalty between propagation aspects of microwave remote sensing sensors and microwave systems at large. The following topics of Remote Sensing, Communication and Navigation are eligible for presentation: Microwave Propagation in Communication and Microwave Sensors - Satellite Communications - Multi-Path Propagation - Indoor Propagation - Digital Broadcast Planning - MIMO Systems and Reuse - Ionospheric Propagation - Urban Communication - Microwave Measurements in Propagation Applications of Microwave Sensors - Radar Polarimetry - Bistatic and Multistatic Radar - Polarimetric and Multistatic Interferometry - Multi-Parameter Weather Radar Systems - Automotive and Airborne Radars - System Calibration - Biological Effects of EM-Radiation - Wave Modulation Remote Sensing Radars Antenna Design and Measurements / Im Rahmen der Aktivitäten des ITG-Fachausschusses 7.5 "Wellenausbreitung" im VDE wurde eine Fachtagung auf dem Gebiet Wellenausbreitung bei Funk-, Mikrowellensystemen und Navigation vom 25. - 27. November 2009 in Chemnitz abgehalten. Die Tagungsphilosophie betont den gemeinsamen Nenner der Wellenausbreitung in diversen Bereichen wie Mikrowellensensorik und Mikrowellensystemen. Dem Leitthema zugeordnet, werden die folgenden Themen aus Fernerkundung, Kommunikation und Navigation besonders berücksichtigt. Mikrowellenausbreitung in der Kommunikation und Mikrowellensensorik - Satellitenkommunikation - Mehrwegeausbreitung - Innen-Gebäude-Übertragung - Frequenzplanung für den digitalen Rundfunk - MIMO Systeme - Wellenausbreitung in der Ionosphäre - urbane Kommunikation - Mikrowellenmessungen der Wellenausbreitung Nutzung und Anwendung in der Mikrowellensensorik - Radar-Polarimetrie - Bistatische und Multistatische Radarverfahren - Polarimetrische und Multistatische Interferometrie - Multiparameter-Wetterradar-Verfahren - Automobil- und Flugzeugradar - Systemkalibrierung - Biologische Effekte der EM-Strahlung - Antennenentwicklung und -messungen für wellenmodulierte Fernerkundungsradare
9

A Performance Analysis of Intrusion Detection with Snort and Security Information Management / En Prestandaanalys av Intrångsdetektering med Snort och Hantering av Säkerhetsinformation

Thorarensen, Christian January 2021 (has links)
Network intrusion detection systems (NIDSs) are a major component in cybersecurity and can be implemented with open-source software. Active communities and researchers continue to improve projects and rulesets used for detecting threats to keep up with the rapid development of the internet. With the combination of security information management, automated threat detection updates and widely used software, the NIDS security can be maximized. However, it is not clear how different combinations of software and basic settings affect network performance. The main purpose in this thesis was to find out how multithreading, standard ruleset configurations and near real-time data shipping affect Snort IDS’ online and offline performance. Investigations and results were designed to guide researchers or companies to enable maximum security with minimum impact on connectivity. Software used in performance testing was limited to Snort 2.9.17.1-WIN64 (IDS), Snort 3.1.0.0 (IDS), PulledPork (rule management) and Open Distro for Elasticsearch (information management). To increase the replicability of this study, the experimentation method was used, and network traffic generation was limited to 1.0 Gbit/s hardware. Offline performance was tested with traffic recorded from a webserver during February 2021 to increase the validity of test results, but detection of attacks was not the focus. Through experimentation it was found that multithreading enabled 68-74% less runtime for offline analysis on an octa-thread system. On the same system, Snort’s drop rate was reduced from 9.0% to 1.1% by configuring multiple packet threads for 1.0 Gbit/s traffic. Secondly, Snort Community and Proofpoint ET Open rulesets showed approximately 1% and 31% dropped packets, respectively. Finally, enabling data shipping services to integrate Snort with Open Distro for Elasticsearch (ODFE) did not have any negative impact on throughput, network delay or Snort’s drop rate. However, the usability of ODFE needs further investigation. In conclusion, Snort 3 multithreading enabled major performance benefits but not all open-source rules were available. In future work, the shared security information management solution could be expanded to include multiple Snort sensors, triggers, alerting (email) and suggested actions for detected threats.
10

Drift-Type Waves in Rotating Tokamak Plasma

Asp, Elina January 2003 (has links)
<p>The concept of energy production through the fusion of two light nuclei has been studied since the 1950’s. One of the major problems that fusion scientists have encountered is the confinement of the hot ionised gas, i.e. the plasma, in which the fusion process takes place. The most common way to contain the plasma is by using at magnetic field configuration, in which the plasma takes a doughnut-like shape. Experimental devices of this kind are referred to as tokamaks. For the fusion process to proceed at an adequate rate, the temperature of the plasma must exceed 100,000,000C. Such a high temperature forces the plasma out of thermodynamical equilibrium which plasma tries to regain by exciting a number of turbulent processes. After successfully quenching the lager scale magnetohydrodynamic turbulence that may instantly disrupt the plasma, a smaller scale turbulence revealed itself. As this smaller scale turbulence behaved contrary to the common theory at the time, it was referred to as anomalous. This kind of turbulence does not directly threaten existents of the plasma, but it allows for a leakage of heat and particles which inhibits the fusion reactions. It is thus essential to understand the origin of anomalous turbulence, the transport it generates and most importantly, how to reduce it. Today it is believed that anomalous transport is due to drift-type waves driven by temperature and density inhomogeneities and the theoretical treatment of these waves is the topic of this thesis.</p><p>The first part of the thesis contains a rigorous analytical two-fluid treatment of drift waves driven solely by density inhomogeneities. Effects of the toroidal magnetic field configuration, the Landau resonance, a peaked diamagnetic frequency and a sheared rotation of the plasma have been taken into account. These effects either stabilise or destabilise the drift waves and to determine the net result on the drift waves requires careful analysis. To this end, dispersion relations have been obtained in various limits to determine when to expect the different effects to be dominant. The main result of this part is that with a large enough rotational shear, the drift waves will be quenched.</p><p>In the second part we focus on temperature effects and thus treat reactive drift waves, specifically ion temperature gradient and trapped electron modes. In fusion plasmas the α-particles, created as a by-product of the fusion process, transfer the better part of their energy to the electrons and hence the electron temperature is expected to exceed the ion temperature. In most experiments until today, the ion temperature is greater than the electron temperature and this have been proven to improve the plasma confinement. To predict the performance of future fusion plasmas, where the fusion process is ongoing, a comprehensive study of hot-electron plasmas and external heating effects have been carried out. Especially the stiffness (heat flux vs. inverse temperature length scale) of the plasma has been examined. This work was performed by simulations done with the JETTO code utilising the Weiland model. The outcome of these simulations shows that the plasma response to strong heating is very stiff and that the plasma energy confinement time seems to vary little in the hot-electron mode.</p>

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