• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 16
  • 4
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 29
  • 29
  • 10
  • 10
  • 9
  • 8
  • 8
  • 7
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
21

Characterization of In-Vivo Damage in Implantable Cardiac Devices and the Lead Residual Properties

Salih, Anmar Mahdi 15 May 2019 (has links)
No description available.
22

Qualitative and quantitative analysis of systems and synthetic biology constructs using P systems

Konur, Savas, Gheorghe, Marian, Dragomir, C., Mierla, L.M., Ipate, F., Krasnogor, N. 04 August 2014 (has links)
Yes / Computational models are perceived as an attractive alternative to mathematical models (e.g., ordinary differential equations). These models incorporate a set of methods for specifying, modeling, testing, and simulating biological systems. In addition, they can be analyzed using algorithmic techniques (e.g., formal verification). This paper shows how formal verification is utilized in systems and synthetic biology through qualitative vs quantitative analysis. Here, we choose two well-known case studies: quorum sensing in P. aeruginosas and pulse generator. The paper reports verification analysis of two systems carried out using some model checking tools, integrated to the Infobiotics Workbench platform, where system models are based on stochastic P systems. / EPSRC
23

Conception de générateurs d'impulsions ultra-large bande en technologie CMOS

Vauché, Rémy 29 November 2011 (has links)
La théorie de l'information développée par Claude Shannon (1916 - 2001) met en évidence le fait que pour accroître la capacité d'un canal de transmission, il est préférable d'élargir la bande de fréquences sur laquelle les informations sont émises plutôt que les puissances d'émissions. Cette constatation est le point de départ de nombreux travaux de recherche sur les communications Ultra-Large Bande (ULB) qui ont abouti en 2002 à la création aux Etats-Unis d'une bande fréquence dîtes ULB où aucun mode de communication n'est privilégié. C'est ainsi que 2 années plus tard ont débuté à l'IM2NP des travaux portant sur les communications ULB impulsionnelles, et notamment la conception d'amplificateur faible bruit, de détecteur d'énergie, mais également de générateurs d'impulsions qui est l'élément clé des émetteurs impulsionnels. Ces derniers constituent la base des travaux présentés dans le manuscrit qui se sont déroulés de 2008 à 2011. La nature discontinue des communications impulsionnelles a tout d'abord impliquée l'introduction de nouvelles figures de mérite permettant de mesurer les performances des générateurs d'impulsions. Ensuite, il est question de méthodes de conception permettant de dimensionner des structures fonctionnant aux fréquences en jeu mais également d'en réduire les consommations statiques principalement de fuite, et ce en vue de répondre aux contraintes de consommation des systèmes embarqués. Enfin sont développées 3 architectures de générateurs d'impulsions, chacune permettant de répondre à des contraintes différentes en termes de bande de fréquences, de consommation et de portée. / The information theory developed by Claude Shannon (1916 - 2001) highlights the fact that in order to increase the capacity of a transmission channel, it is preferable to extend the bandwidth used rather than the transmission power. This finding is the starting point of many papers on Ultra-Wideband (UWB) which led to the creation in the United States of UWB band since 2002 where no modulation is privileged. Two years later, many works on Impulsionnal Radio UWB (IR-UWB) communications began at IM2NP including the design of low noise amplifier, power detector, but also pulse generators which is the key element of IR-UWB emitters. These form basis of works presented in the manuscript that took place from 2008 to 2011. The discontinuous nature of communications impulse was first implied the introduction of new figures of merit for measuring performances of pulse generators. Then it deals with design techniques for sizing structures operating at frequencies involved, but also to reduce consumption and especially static leakage to reduce enough power consumption for embedded systems. Finally three architectures of pulse generators are developed, each one responding to different constraints in terms of frequency, consumption and range.
24

High voltage transient protection for automotive

Lindholm, Viktor January 2019 (has links)
Electronics for automotive needs to be able to handle different situations that can occur on the power line, such as high voltage transients. ISO16750 and ISO-7637 describes different pulses and tests a system needs to be able to handle. This report compares three different protection circuits that can output +5V and +12V built for low power devices. The circuits use different techniques for protection, one that uses TVS diodes, another that uses a voltage regulator IC with built in protection. The last protection uses P-channel MOSFET’s for protection. The circuits are compared against protection, price and leakage current. The most relevant transients to test a system against are decided to be pulse1, pulse 2a and load dump. A pulse generator consisting of a pulse shaping network and a common drain amplifier is used to create the test pulses. The result shows that all the circuits could protect against pulse 2a and load dump. However, all the circuits did fail against pulse 1 due to an undersized diode for negative voltage protection. The leakage current did not exceed 4µA for two of the circuits in the temperature interval of -40°C to +100°C. All the circuits started to have high leakage current when the temperature got up to +150°C. The price for the circuits didn’t differ that much, all the circuits cost below 3 US-dollar per circuit when making 10 000 circuits. The conclusions that could be made of the results are that all the circuits could protect against pulse 1, pulse 2a and load dump if correct diode is used for negative voltage protection. The protection that builds on Pchannel MOSFET’s should be the best choice for low power devices due to its low leakage current and potential for low cost. The disadvantage is the complexity and number of components needed for the circuit. The TVS diodes should be used if low complexity and low number of components is preferred. The disadvantage is that TVS diodes gets hot if a load dump is applied and the interval between stand-off voltage and maximum clamping voltage is quite high. The study also shows that there are cheaper solutions than using TVS diodes.
25

Systémy pro generování impulsního magnetického vektorového potenciálu / Systems for Generation of Pulse Magnetic Vector Potential

Hanák, Pavel January 2012 (has links)
The doctoral thesis is focused on research, design, implementation and testing of systems for the application of magnetic vector potential to biological materials. The main objective was to analyze and design systems which could generate magnetic vector potential without the presence of other unwanted fields or at least amplify its intensity. Moreover, the systems designed had to eliminate other foreign effects on the biological samples, especially the influence of waste heat from the coils. Toroidal coils were employed to generate the vector potential, because they confine the unwanted magnetic induction inside their core thanks to their shape. The thesis employed coils with two different outer diameters, specifically 102 and 600 mm. To excite the coils, four current pulse generators capable of delivering currents of up to 100 A were constructed. The systems’ generated fields were comprehensively analyzed with the help of finite-element simulations in ANSYS. To simplify the design phase, analytical equations for the calculation of vector potential intensity at an arbitrary point around the toroidal coils were also derived. A method employing electromagnetic shielding made of two different materials was developed to suppress the unwanted fields. To eliminate the influence of heat, the 102 mm system employed air cooling and the 600 mm system employed a closed water loop to equalize the temperatures of biological samples. The biological effects of both systems were tested on genetically modified bio-luminescent bacteria Escherichia coli K12 luxABCDEamp. The thesis was created in connection with the research project of The Ministry of Education, Youth and Sports of the Czech Republic named “Research into the effect of a combination of substances for targeted therapy and inhibitory action of the field pulse vector magnetic potential on oncogenous diseases”, No. 2B08063.
26

Optimisation des performances d'un procédé industriel d'électrofiltration alimenté par hautes puissances pulsées / Performance optimization of an industrial electrofiltration process supplied by high pulsed powered

Souakri, Sonia 09 December 2016 (has links)
La lutte contre la pollution atmosphérique est un enjeu majeur de ce XXIème siècle. Le centre deMarcoule du CEA développe différents procédés de traitement de déchets issus du nucléaire parincinération/vitrification qui génèrent des gaz de combustion nécessitant un traitement. Pour cefaire, le CEA utilise la précipitation électrostatique, technique de traitement d’effluents gazeuxemployée pour la filtration des particules fines.Cette thèse est consacrée à l’optimisation des performances d’un électrofiltre alimenté parhautes puissances pulsées. L’un des objectifs est de dimensionner et réaliser une nouvelle électrodeémissive adaptée au développement d’un nouveau procédé d’incinération. Cette nouvelle électrodecouplée à son alimentation HT, dont les paramètres électriques ont été optimisés, ont permisd’obtenir des rendements de filtration maximum durant des temps de fonctionnement enadéquation avec des applications industrielles. L’impact des caractéristiques physico-chimiques despoussières sur l’efficacité de filtration a été analysé.Une étude spécifique a également porté sur l’évolution des différents régimes de décharge quise développent dans l’électrofiltre de manière à identifier les phénomènes responsables de la chuted’efficacité du procédé. Les bénéfices de l’électrode émissive et d’un générateur hybride, combinantdes impulsions de tension superposées à un fond continu, ont clairement été mis en évidence parleurs effets sur l’initiation des "back corona" et par conséquent sur la durée de fonctionnement àrendement optimal. / The fight against air pollution is a major issue in the twenty-first century. The center of Marcouleof CEA develops different waste treatment processes by incineration / vitrification that generatecombustion gases requiring treatment. To do this, the CEA uses the electrostatic precipitation, atechnical waste gas treatment employed for thin particles filtration.This thesis is dedicated to optimizing the performance of an electrofilter supplied by high pulsedpowered. One of the goals is to size and achieve a new emissive electrode adapted to thedevelopment of a new incineration process. This new electrode coupled to its High Voltage (HV)power supply, which electrical parameters were optimized, allowed to obtain maximum filtrationefficiency during operating times in line with industrial applications. The impact of thephysicochemical characteristics of dusts on the filtration efficiency was analyzed.A specific study also focused on the evolution of different discharge conditions that develop inthe electrofilter to identify the phenomena responsible for the process efficiency fall. The intake ofthe emissive electrode and a hybrid generator, combining a continuous background voltagesuperimposed with impulses, has clearly been demonstrated by their effects on back coronainitiation and therefore on the optimal efficiency operation duration.
27

Étude d’un protocole de communication asynchrone faible consommation à lien radio impulsionnel ultra-large bande : implémentation sur silicium des fonctions RF critiques / Radio triggered asynchronous protocol for ULP sensor network based on a UWB sub-GHz communication link : critical RF functions design

Haloua, Abderrahmane 13 July 2018 (has links)
Au cours des dernières années, différents travaux de recherche ont été consacrés à l’étude et au développement des solutions de type réseau de capteurs sans fil. Ces travaux sont une réponse à l’augmentation du nombre d’objets connectés dans le monde avec le développement de l’internet des objets. La consommation d’énergie dans les réseaux de capteurs représente un des domaines les plus étudiés. Les communications dans les réseaux de capteurs représentent une part importante de leur consommation. Afin de réduire la consommation des communications dans les réseaux de capteurs, différents niveaux d’optimisation sont possibles. Dans ce contexte, différents travaux de recherches visant à réduire la consommation des émetteurs-récepteurs, grâce à des architectures innovantes, ont été menés à l’IM2NP. Beaucoup de ces travaux ont été consacrés aux radios impulsionnelles Ultra-Large Bande (ULB). En outre, les protocoles d’accès aux canaux de communications dans les réseaux de capteurs sont également importants quant à l’optimisation de leurs consommations. Les travaux de recherches proposés dans ce manuscrit, basés sur les travaux sur les radios impulsionnelles ULB réalisés au sein de l’IM2NP, proposent une optimisation de la consommation des réseaux de capteurs sur deux niveaux. Tout d’abord, un protocole asynchrone à base de radio de réveil d’accès au canal de communication adapté aux communications ULB est proposé ainsi que son étude énergétique. Suite à l'étude du protocole asynchrone proposé, la conception d’un récepteur de réveil semi-passif et d’un générateur d’impulsion ULB sous-GHz est abordée, et leurs performances en termes d’efficacité énergétique discutées. / In recent years, research has been devoted to the study and development of Wireless Sensor Network (WSN). These research are a response to the increase of the connected objet number in the world with development of smartphones and Internet of things (IoT). Energy consumption in sensor networks is one of the most studied areas. In fact, the optimization of the consumption of the elements making up the sensor networks allows a reduction in the costs associated with their installation, operation and maintenance. Communications in sensor networks represent an important part of their power consumption. In order to reduce the consumption of communications in sensor networks, different levels of optimization are possible. In this context, various IM2NP research projects aimed at reducing transceiver consumption through innovative design were carried out. Much of this work has been devoted to Impulsionnal Radio Ultra-Wide Band (IR-UWB). Moreover, MAC protocols used to manage the communication channel access in wireless sensor networks are also important in optimizing their consumption. The research work proposed in this manuscript, based on the work on impulse radios UWB carried out within the IM2NP, propose an optimization of the consumption of sensor networks on two levels. Firstly, an asynchronous MAC protocol based on radio wake-up radio suitable for UWB communications is proposed as well as its energy study. Following the study of the proposed asynchronous protocol, the design of a low power semi-passive wake-up receiver (WuRx) and a UWB sub-GHz impulse generator is presented and their performance in terms of energy efficiency discussed.
28

An Energy-Efficient Impulse Radio Ultra Wideband (IR-UWB) Transceiver for High-Rate Biotelemetry

Ebrazeh, Ali 03 September 2015 (has links)
No description available.
29

Zdroj pro pulzní magnetronové naprašování / Power source for pulse magnetron sputtering

Schulz, Jakub January 2008 (has links)
The presented thesis deals with the design and assembly of the generator for pulse magnetron sputtering. The designed device is capable of generating two square wave signals via its counter-working outputs. Both signals have independently adjustable frequency, pulse count and duty ratio. Both signals originate from two frequency syntheses controlled by microcontroller PIC16F877A. All the settings are entered by four buttons and are shown on an alphanumeric display with 16x4 characters. The duty ratio is adjusted using a special module.

Page generated in 0.0661 seconds