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1
Kumar, Akhilesh. "Leakage Power Modeling and Reduction Techniques for Field Programmable Gate Arrays." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/766.
Повний текст джерелаАнотація:
FPGAs have become quite popular for implementing digital circuits and systems because of reduced costs and fast design cycles. This has led to increased complexity of FPGAs, and with technology scaling, many new challenges have come up for the FPGA industry, leakage power being one of the key challenges. The current generation FPGAs are being implemented in 90nm technology, therefore, managing leakage power in deep-submicron FPGAs has become critical for the FPGA industry to remain competitive in the semiconductor market and to enter the mobile applications domain. In this work an analytical state dependent leakage power model for FPGAs is developed, followed by dual-Vt based designs of the FPGA architecture for reducing leakage power.
The leakage power model computes subthreshold and gate leakage in FPGAs, since these are the two dominant components of total leakage power in the scaled nanometer technologies. The leakage power model takes into account the dependency of gate and subthreshold leakage on the state of the circuit inputs. The leakage power model has two main components, one which computes the probability of a state for a particular FPGA circuit element, and the other which computes the leakage of the FPGA circuit element for a given input using analytical equations. This FPGA power model is particularly important for rapidly analyzing various FPGA architectures across different technology nodes.
Dual-Vt based designs of the FPGA architecture are proposed, developed, and evaluated, for reducing the leakage power using a CAD framework. The logic and the routing resources of the FPGA are considered for dual-Vt assignment. The number of the logic elements that can be assigned high-Vt in the ideal case by using a dual-Vt assignment algorithm in the CAD framework is estimated. Based upon this estimate two kinds of architectures are developed and evaluated, homogeneous and heterogeneous architectures. Results indicate that leakage power savings of up to 50% can be obtained from these architectures. The analytical state dependent leakage power model developed has been used for estimating the leakage power savings from the dual-Vt FPGA architectures. The CAD framework that has been developed can also be used for developing and evaluating different dual-Vt FPGA architectures, other than the ones proposed in this work.
2
Dastrup, Emily Joy. "Estimating the Discrepancy Between Computer Model Data and Field Data: Modeling Techniques for Deterministic and Stochastic Computer Simulators." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd986.pdf.
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Бойко, Антон Миколайович. "Діагностика полімерної ізоляції в процесі старіння кабелів під дією сильного електричного поля за трибоелектричним потенціалом". Thesis, НТУ "ХПІ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/19647.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. Національний технічний університет "Харківський політехнічний інститут", Харків, 2015. Дисертація присвячена розробці та обґрунтуванню діагностики за трибоелектричним потенціалом для виявлення зміни поверхневих властивостей полімерної ізоляції в процесі старіння кабелів під дією сильного електричного поля, підвищеної температури та іонізуючого випромінювання. В процесі старіння для двошарової ізоляції на основі застосування схеми заміщення встановлено появу струмів, що змінюються по експоненціальному закону, та отримано динаміку в часі накопичення, рекомбінації та релаксації поверхневого заряду на границі розділу. Встановлено розподіл густини поверхневого заряду по довжині симетричних ізольованих провідників при наявності між ними зазору та тонкого дефектного шару на поверхні полімерної ізоляції на основі отриманого аналітичного рішення. Показано, що окиснений прошарок на поверхні ізоляції призводить по появи сильного електричного поля. В залежності від конструктивного виконання і застосованих матеріалів експериментально визначено значення трибоелектричного потенціалу та встановлена динаміка його зміни в процесі прискореного терморадіаційного старіння кабелів. Встановлено вплив поверхневих та трибозарядів на результати діагностичних обстежень кабелів за опором ізоляції на високій напрузі. Запропонована діагностика за трибоелектричним потенціалом силових, контрольних та інформаційних кабелів дозволяє виявити зміну поверхневих властивостей полімерної ізоляції в процесі старіння кабелів.Thesis for granting Candidate of Technical sciences Degree in specialty 05.09.13 – Technics of Strong Electric and Magnetic Fields. – National Technical University "Kharkiv Polytechnic Institute", 2015. The thesis is devoted to development and diagnostic system for substantiation triboelectric potential to detect changes in surface properties of polymer isolation in aging cables under the strong electric field, high temperature and radiation. The distribution of surface charge density and voltage drop along the length of symmetrical insulated conductors in the presence of the gap between them and the defective thin layer on the surface of the polymer insulation was established based on the analytical solution. Experimentally determined the values of triboelectric potential and its dynamics of change in the process of accelerated termoradiation aging polymer cable insulation depending on the design of applied materials. There is a significant (threefold) increase in the maximum value of the contact potential difference and achieve maximum torque bias towards smaller values for single core power cables with cross-linked polyethylene insulation 6 kV after accelerated aging thermoradiation. This confirms the high sensitivity of triboelectric potential to aging and allows us to make a suggestion to use this parameter as an indicator of the polymeric insulation aging degree. Influence of surface charges and tribocharges on the results of diagnostic tests on the insulation resistance and stability during the measurement capacitance and dielectric loss tangent cables with polymer insulation was observed. Dynamics of changes in contact potential difference in the aging process power cables with different materials remains consistent with the results of diagnostic tests of capacity and dielectric loss tangent.
4
Бойко, Антон Миколайович. "Діагностика полімерної ізоляції в процесі старіння кабелів під дією сильного електричного поля за трибоелектричним потенціалом". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/19642.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. Національний технічний університет "Харківський політехнічний інститут", Харків, 2015.
Дисертація присвячена розробці та обґрунтуванню діагностики за трибоелектричним потенціалом для виявлення зміни поверхневих властивостей полімерної ізоляції в процесі старіння кабелів під дією сильного електричного поля, підвищеної температури та іонізуючого випромінювання. В процесі старіння для двошарової ізоляції на основі застосування схеми заміщення встановлено появу струмів, що змінюються по експоненціальному закону, та отримано динаміку в часі накопичення, рекомбінації та релаксації поверхневого заряду на границі розділу. Встановлено розподіл густини поверхневого заряду по довжині симетричних ізольованих провідників при наявності між ними зазору та тонкого дефектного шару на поверхні полімерної ізоляції на основі отриманого аналітичного рішення. Показано, що окиснений прошарок на поверхні ізоляції призводить по появи сильного електричного поля. В залежності від конструктивного виконання і застосованих матеріалів експериментально визначено значення трибоелектричного потенціалу та встановлена динаміка його зміни в процесі прискореного терморадіаційного старіння кабелів. Встановлено вплив поверхневих та трибозарядів на результати діагностичних обстежень кабелів за опором ізоляції на високій напрузі. Запропонована діагностика за трибоелектричним потенціалом силових, контрольних та інформаційних кабелів дозволяє виявити зміну поверхневих властивостей полімерної ізоляції в процесі старіння кабелів.Thesis for granting Candidate of Technical sciences Degree in specialty 05.09.13 – Technics of Strong Electric and Magnetic Fields. – National Technical University "Kharkiv Polytechnic Institute", 2015. The thesis is devoted to development and diagnostic system for substantiation triboelectric potential to detect changes in surface properties of polymer isolation in aging cables under the strong electric field, high temperature and radiation. The distribution of surface charge density and voltage drop along the length of symmetrical insulated conductors in the presence of the gap between them and the defective thin layer on the surface of the polymer insulation was established based on the analytical solution. Experimentally determined the values of triboelectric potential and its dynamics of change in the process of accelerated termoradiation aging polymer cable insulation depending on the design of applied materials. There is a significant (threefold) increase in the maximum value of the contact potential difference and achieve maximum torque bias towards smaller values for single core power cables with cross-linked polyethylene insulation 6 kV after accelerated aging thermoradiation. This confirms the high sensitivity of triboelectric potential to aging and allows us to make a suggestion to use this parameter as an indicator of the polymeric insulation aging degree. Influence of surface charges and tribocharges on the results of diagnostic tests on the insulation resistance and stability during the measurement capacitance and dielectric loss tangent cables with polymer insulation was observed. Dynamics of changes in contact potential difference in the aging process power cables with different materials remains consistent with the results of diagnostic tests of capacity and dielectric loss tangent.
5
Papalexopoulos, Alexis D. "Modeling techniques for power system grounding systems." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/13529.
Повний текст джерела
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Babineau, David. "Modeling the electric field and natural environment of weakly electric fish." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27222.
Повний текст джерелаАнотація:
Weakly electric fish use a unique sensory modality in order to help them communicate, navigate and find prey. These fish emit electric discharges that are monitored by electroreceptors located in the fish's skin. Surrounding objects perturb these baseline transdermal potentials and create electric images. The study of these images has led to a better understanding of general sensory processing principles; however, many aspects of these fish's natural electrosensory environment remain unknown. To this end, a two-dimensional finite element model of Apteronotus leptorhynchus was created. Using this model, we suggest new ways by which electric fish are able to locate objects and propose that it is possible for these fish to extract useful information from their environment using their natural scanning behaviour. Our results also reveal important limitations in standard experimental paradigms that aim to mimic the effects of conspecifics. Alternative paradigms that will enable more realistic stimulation are suggested.
7
Zhang, Minya. "Optoelectronic device modeling using field simulation techniques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/NQ42892.pdf.
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Andersson, Helena. "Individualized mathematical modeling of neural activation in electric field." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-313150.
Повний текст джерелаАнотація:
Deep Brain Stimulation (DBS) is a treatment of movement disorders such as Parkinson's disease and essential tremor. Today it has been used in more than 80.000 patients. Electrical stimulation is administered by an implanted pulse generator through an electrode surgically placed in a target brain area specific to the treated disease. Opposed to alternative purely surgical treatment procedures, DBS is reversible and can be turned off. In this project, the aim is to individualise an already existing computational model of DBS, but also to look at optimisation of the treatment by developing a neuron model. It has been executed the following way. To localise the target area for the electrode, Magnetic Resonance Imaging (MRI) is used. An MRI image consists of volume elements called voxels. By analysing these voxels, it is possible to set up a coordinate system for the position of different parts of the brain. To build up an individualised model of the DBS, an MRI image is segmented into tissues of different conductivity thus resulting in a more accurate description of the electrical field around the electrode. To visualize the stimuli coverage for the medical staff, the MRI image of the target area, the electrode, and the electrical field produced by the stimuli are depicted in the same figure. From the results, we can draw the conclusion that this method works well for individualising the computational model of DBS, but it has only been used on one MRI scan so far so it needs further testing to obtain more data to compare with. The neuron model is a temporospatial mathematical model of a single neuron for the prediction of activation by a given electrically applied field generated by a DBS lead. The activation model is intended to be part of a patient-specific model of an already existing computational model of DBS. The model originate from a neuron model developed by Hodgkin and Huxley (HH). The original HH model only takes into account one compartment and, to make the neuron model more accurate, it is combined with a cable model. The simulation results obtained with the model have been validated against an established and widely accepted neuron model. The results correlated highly to each other with only minor differences. To see how position and orientation impact on activation, the developed HH model was tested for different pulse widths, distances from the lead, and rotations of the neuron relative to the lead. A larger pulse width makes activation more likely and so does a larger amplitude. Thicker neurons are more likely to get activated, neurons closer to the lead and also neurons perpendicular to the lead. From the results we can draw the conclusion that this method is a good way to stimulate neural activation of a single neuron. In future research, it might be possible to compare results from the neuron model with patient's response to treatment.
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De, Marco Tommaso <1980>. "Parallel modeling of the electric field distribution in the brain." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3618/.
Повний текст джерелаАнотація:
The term "Brain Imaging" identi�es a set of techniques to analyze the structure and/or functional behavior of the brain in normal and/or pathological situations. These techniques are largely used in the study of brain activity.
In addition to clinical usage, analysis of brain activity is gaining popularity in others recent �fields, i.e. Brain Computer Interfaces (BCI) and the study of cognitive processes. In this context, usage of classical solutions (e.g. f MRI, PET-CT) could be unfeasible, due to their low temporal resolution, high cost and limited portability. For these reasons alternative low cost techniques are object of research, typically based on simple recording hardware and on intensive data elaboration process. Typical examples are ElectroEncephaloGraphy (EEG) and Electrical Impedance Tomography (EIT), where electric potential at the patient's scalp is recorded by high impedance electrodes. In EEG potentials are directly generated from neuronal activity, while in EIT by the injection of small currents at the scalp. To retrieve meaningful insights on brain activity from measurements, EIT and EEG relies on detailed knowledge of the underlying electrical properties of the body. This is obtained from numerical models of the electric �field
distribution therein. The inhomogeneous and anisotropic electric properties of human tissues make accurate modeling and simulation very challenging, leading to a tradeo�ff between physical accuracy and technical feasibility,
which currently severely limits the capabilities of these techniques. Moreover elaboration of data recorded requires usage of regularization techniques computationally intensive, which influences the application with heavy temporal constraints (such as BCI).
This work focuses on the parallel implementation of a work-flow for EEG and EIT data processing. The resulting software is accelerated using multi-core GPUs, in order to provide solution in reasonable times and address requirements of real-time BCI systems, without over-simplifying the complexity and accuracy of the head models.
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Weinstein, Randall Kenneth. "Techniques for FPGA neural modeling." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/26685.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Bioengineering, Georgia Institute of Technology, 2007.Committee Chair: Lee, Robert; Committee Member: Butera, Robert; Committee Member: DeWeerth, Steve; Committee Member: Madisetti, Vijay; Committee Member: Voit, Eberhard. Part of the SMARTech Electronic Thesis and Dissertation Collection.
11
Moulton, Derek E. "Mathematical modeling of field driven mean curvature surfaces." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 242 p, 2008. http://proquest.umi.com/pqdweb?did=1597617631&sid=12&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Au, Yi-ching. "Leakage power modeling and reduction techniques for nanometer scale VLSI circuits /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20AUY.
Повний текст джерелаАнотація:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 59-61). Also available in electronic version. Access restricted to campus users.
13
Karimi, Sharif Hamed. "Degradation of silicon nitride glow plugs in electric field-experiments and modeling." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36256.
Повний текст джерелаАнотація:
Silicon nitride (Si₃N₄) based ceramic Glow Plugs (GP) are considered by the automotive industry as a reliable, long-term source of ignition for natural gas and hydrogen internal combustion engines. The commercial GPs investigated in this work comprised of an all-ceramic heater with two U-shaped tungsten carbide heating elements encased in an Yb₂O₃-doped silicon-nitride (Si₃N₄) insulating phase. Upon applying electric potentials of 10-14V, the temperature on the surface of ceramic heater rapidly raises to as high as 1500ºC. This work looks into various modes of deterioration of GPs, particularly resulting from interaction of high operating temperature and the electric field within the GP heaters. An extensive scanning electron microscopy and energy dispersive x-ray spectroscopy investigation was performed to determine the degradation mechanisms of GPs in natural gas-burning rig, electric rig and engine. GP testing has shown that under the influence of constant electric load (DC) the sintering aid (Yb₂O₃) cations continuously migrate away from the high potential side of the heating elements following the electric field pattern. A 2D mathematical model was developed to simulate the redistribution of the sintering additive (Yb₂O₃) cations as a function of time, temperature, and electric field. The damage pattern of the tested GPs suggests synergistic impact of temperature, voltage, and environment on GPs lifetime. For the GPs tested in the burner rig and in engine the internal joule heating, externally applied combustion heat, together with the corrosive nature of the combustion gases, synergistically contribute to the degradation of Si₃N₄-based heaters. The comparison of cross sections for aged GPs revealed an increase in Yb ions migration with increasing temperature, electric field, and test duration. This study confirms that the removal of just one of the failure stimuli may significantly improve the GP performance. For example, applying AC voltage provided a significant improvement of GP durability in electric rig, even without addressing any other damage phenomena.
14
Chen, Shuoqi. "Characterization of semiconductor-based guided wave structures using field theoretical analysis techniques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21927.pdf.
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Zhang, Yanjing. "Electric and magnetic contributions and defect interactions in remote field eddy current techniques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22507.pdf.
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Liu, Jingbo. "Modeling, analysis and design of integrated starter generator system based on field oriented controlled induction machines." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1132763176.
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17
Guffond, Raphaël. "Characterization and modeling of microstructure evolution of cable insulation system under high continuous electric field." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS039/document.
Повний текст джерелаАнотація:
Le sujet de cette thèse porte sur la compréhension et la modélisation du comportement électrique de système d'isolation soumis à un fort champ électrique continu. Les propriétés électriques du polymère sont directement pilotées par ses hétérogénéités chimiques et physiques présentes à plusieurs échelles. Dans cette étude, un nouveau modèle est développé ayant pour but de simuler l'évolution de la microstructure de polymère avec la température, le champ électrique et le temps et de simuler l'impact de cette évolution sur les propriétés électriques du polymère. Dans ce modèle, des matrices sont utilisées pour décrire la distribution de chacune des hétérogénéités et propriété électriques d'un polymère semi-cristallin. L'évolution de ces matrices de microstructure suit des lois génétiques dont la définition a été obtenue à partir d'une caractérisation fine des propriétés physicochimiques et électriques de matériaux spécifiques en fonction de la température et du champ électrique. Ces lois implémentées sont basés sur des calculs simples permettant un temps de résolution plus rapide comparativement aux autres modèles préexistants. Basée sur ces lois d'évolutions génétiques, le comportement électrique sous champ électrique continue de polymère isolant peut être simulé uniquement à partir d'une caractérisation physique et chimique de ce polymère. Le modèle est ainsi capable de reproduire le comportement électrique de plusieurs polymères semi-cristallins et de suivre les données expérimentales mesurées par ailleurs. Le modèle intègre plusieurs physiques tels que la diffusion, le transport ionique et le transport électronique, lui permettant ainsi de prendre en compte l'influence d'un grand nombre d'hétérogénéitésThis thesis presents a research work on understanding and modeling the electrical behavior of insulation system in cables subjected to high DC constraints. Electrical properties of polymeric insulation are directly related to their chemical and physical heterogeneities present at several scales. In this work, a new model is developed to simulate the modification over time of the microstructure in insulation polymers under electric field and temperature as well as the subsequent impacts on electrical properties. In this model, matrices are used to describe the distribution of each heterogeneity and electrical property in semi-crystalline polymer. When stressed under electric field and at temperature, matrices of microstructure evolve from implemented genetic laws. This simulated microstructure evolution yields to the simulation of electrical property changes over time at transient and steady state. To define these genetic laws, a detailed characterization of the physical, chemical and electrical properties of specific materials as a function of temperature and electric field is experimentally performed. Genetic laws are notably implemented to take into account the impact of the semi-crystalline structure and the presence of chemical residues in polymer electrical properties. Based on these genetic evolution laws, this modeling approach allows simulating DC electrical behavior of polymers only from their physical and chemical characterizations and reproduce accurately experimental electrical behavior with a faster solving time compared to other simulation methods
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Panicker, Nithin S. "Numerical Modeling of Flow and Deformations Induced in a Droplet Subjected to Alternating Electric Field." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729917.
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Cai, Haiwei. "Modeling and Control of Dual Mechanical Port Electric Machine." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449247852.
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Essah, David N. "New modeling techniques for power electronics based systems with application to switched reluctance drives /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9962521.
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Trainito, Claudia. "Study of cell membrane permeabilization induced by pulsed electric field – electrical modeling and characterization on biochip." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN008/document.
Повний текст джерелаАнотація:
Depuis plusieurs années, de nouvelles méthodologies basées sur l’utilisation du champ électrique pour agir ou caractériser les cellules ou les tissus cellulaires génèrent de nombreuses avancées et apportent des nouvelles promesses dans les laboratoires de recherche et dans l'industrie : diagnostic de cancer, ElectroChimioThérapie (insertion d’un médicament en perméabilisant les membranes des cellules), thérapie génique (insertion d’un gène thérapeutique), immunothérapie (vaccins anti-tumoraux obtenus par électrofusion de cellules dendritiques et cellules cancéreuses pour réactiver le système immunitaire).L’application d’ impulsions électriques à des cellules ou dans des tissus cellulaires induit un changement sur leurs propriétés, en particulier sur leurs membranes qui deviennent transitoirement perméables, laissant temporairement le passage aux ions et macro-molécules. Les phénomènes induits lors d’une perméabilisation par application de champ électrique ont été partiellement caractérisés en microscopie epi-fluorescence. Pour effectuer un suivi en temps réel de la dynamique du processus de l’électroperméabilisation, une voie prometteuse consiste à caractériser électriquement l’échantillon. Dans cet objectif, mon travail de thèse consiste à mettre en oeuvre le suivi en temps réel de l’évolution des caractéristiques électriques sur une large bande de fréquences d’un tissu cellulaire ou d’une cellule isolée, avant, pendant et après la sollicitation par un champ électrique pulsé.Dans le cadre de ma thèse un modèle du système biologique et de son environnement a été élaboré, afin de mieux décrire des phénomènes observés expérimentalement: effet des sollicitations électriques sur la viabilité cellulaire, sur la perméabilité de la membrane externe, effets induits sur les composés intracellulaires, dynamique de fusion membranaire. Le degré de perméabilisation de l’objet biologique (cellule ou tissu) dépend de manière fortement non-linéaire de nombreux paramètres, ce qui rend complexe l’élaboration de ce modèle et son interprétation. La détection de ce niveau de perméabilisation est effectuée en temps réel (mesure du niveau de perméabilisation avant, pendant et après l’application de l’impulsion électrique). In fine cette approche devrait permettre d’optimiser le taux de perméabilisation cellulaire en fonction de l’application considérée. Ce système de contrôle individuel du niveau de perméabilisation cellulaire pourrait à terme être parallélisé massivement sur une puce dédiée à l’électroporation d’un grand nombre de cellules. Afin d’avoir une vision multi-échelle des effets, l’étude a été menée sur plusieurs modèles expérimentaux: qui vont du tissu (échelle millimétrique) à la cellule unique, en passant par les échelles intermédiaires (caractérisation de spéroides cellulaires).Dans ces deux derniers cas (sphéroide, cellule unique) l’objet biologique est isolé dans une biopuce microfluidique équipée d’électrodes de mesure et d’application du champ (échelle micrométrique).Les micro-dispositifs que j’ai réalisé pour caractériser en temps réel la perméabilisation de cellules, intègrent une géométrie spécifique d’électrodes, ainsi que d'un réseau de canaux microfluidiques pour contrôler le débit de cellules Le degré de miniaturisation de ces puces permet de travailler au niveau de la cellule unique, et appliquer des champs électriques de forte amplitude, de forte fréquence, localisés spatialementThe increasing interest for new methodologies based on the use of the electric field to characterize the cells or tissue cells and generate brought promising development in research laboratories and industry: cancer diagnosis, electrochemotherapy (insertion of a drug after cell membranes permeabilization), gene therapy (insertion of a therapeutic gene), immunotherapy (anti-tumor vaccines obtained by electrofusion of dendritic cells and cancer cells to activate the immune system).The application of electrical pulses to cells or cell tissues induces a change in their properties, in particular on their membranes which become transiently permeable, and temporarily allow the passage of ions and macromolecules. Effect linked to the permeabilization phenomenon have been partially characterized by epi-fluorescence microscopy. Nevertheless, in order to perform the real-time monitoring of the electroporation process and know its dynamics, the electrical sample characterization is employed. Thus the aim of this work is to implement a real-time monitoring of dielectrical characteristics changes, on a wide frequency range, of a cellular tissue or a single cell, before, during and after the pulsed electric field application.As part of my thesis a model of the biological system has been developed to better describe the phenomena observed experimentally: effect of electrical stress on cell viability, on the permeability of the outer membrane, induced effects on the intracellular compounds, dynamics of membrane fusion.The degree of permeabilization of the biological sample (cells or tissues) is non linearly dependent of several parameters, which makes complicated the development of the model and its interpretation.The detection of a specific level of permeabilization is done in real time (measure of the level of permeabilization before, during and after the electric pulses application). This cell permeabilization level control could eventually be parallelized on a chip dedicated to the electroporation of a large number of cells. The latter can be used to optimize the electric pulses parameters in order to reach the desired permeabilization level. In order to have a multi-scale overview of the phenomenon, the study was performed on different size-level: from the tissue level (millimeter scale) to the single cell model through the intermediate scales (cell spéroides characterization).In the latter two cases (spheroid, single cell) the biological sample is isolated in a microfluidic biochip where the electric field solicitation are applied (micrometer scale).The microdevice designed and fabricated during this work, allows the real time characterization of the cell permeabilization. Furthermore the miniaturization of the system is crucial to work at the level of the single cell, and make possible the application of electrical fields of high amplitude, high frequency and spatially localized
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Akin, Bilal. "State Estimation Techniques For Speed Sensorless Field Oriented Control Of Induction Motors." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1055953/index.pdf.
Повний текст джерелаАнотація:
This thesis presents different state estimation techniques for speed sensorlees
field oriented control of induction motors. The theoretical basis of each algorithm is
explained in detail and its performance is tested with simulations and experiments
individually.
First, a stochastical nonlinear state estimator, Extended Kalman Filter (EKF)
is presented. The motor model designed for EKF application involves rotor speed,
dq-axis rotor fluxes and dq-axis stator currents. Thus, using this observer the rotor
speed and rotor fluxes are estimated simultaneously. Different from the widely
accepted use of EKF, in which it is optimized for either steady-state or transient
operations, here using adjustable noise level process algorithm the optimization of
EKF has been done for both statesthe steady-state and the transient-state of operations. Additionally, the measurement noise immunity of EKF is also investigated. Second, Unscented Kalman Filter (UKF), which is an updated version of EKF, is proposed as a state estimator for speed sensorless field oriented control of induction motors. UKF state update computations, different from EKF, are derivative free and they do not involve costly calculation of Jacobian matrices. Moreover, variance of each state is not assumed Gaussian, therefore a more realistic approach is provided by UKF. In this work, the superiority of UKF is shown in the state estimation of induction motor. Third, Model Reference Adaptive System is studied as a state estimator. Two different methods, back emf scheme and reactive power scheme, are applied to MRAS algorithm to estimate rotor speed. Finally, a flux estimator and an open-loop speed estimator combination is employed to observe stator-rotor fluxes, rotor-flux angle and rotor speed. In flux estimator, voltage model is assisted by current model via a closed-loop to compensate voltage model&rsquo
s disadvantages.
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Liu, Yansheng. "Investigation of Novel Microseparation Techniques." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1816.pdf.
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Li, Zhao. "Subsurface Simulation Using Stochastic Modeling Techniques for Reliability Based Design of Geo-structures." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1466691128.
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Woodburn, David. "Modeling and Simulation of All-electric Aircraft Power Generation and Actuation." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6037.
Повний текст джерелаАнотація:
Modern aircraft, military and commercial, rely extensively on hydraulic systems. However, there is great interest in the avionics community to replace hydraulic systems with electric systems. There are physical challenges to replacing hydraulic actuators with electromechanical actuators (EMAs), especially for flight control surface actuation. These include dynamic heat generation and power management.
Simulation is seen as a powerful tool in making the transition to all-electric aircraft by predicting the dynamic heat generated and the power flow in the EMA. Chapter 2 of this dissertation describes the nonlinear, lumped-element, integrated modeling of a permanent magnet (PM) motor used in an EMA. This model is capable of representing transient dynamics of an EMA, mechanically, electrically, and thermally.
Inductance is a primary parameter that links the electrical and mechanical domains and, therefore, is of critical importance to the modeling of the whole EMA. In the dynamic mode of operation of an EMA, the inductances are quite nonlinear. Chapter 3 details the careful analysis of the inductances from finite element software and the mathematical modeling of these inductances for use in the overall EMA model.
Chapter 4 covers the design and verification of a nonlinear, transient simulation model of a two-step synchronous generator with three-phase rectifiers. Simulation results are shown.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Ho, Wai. "GaAs MESFET modeling and its applications." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1175707072.
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Mesgarpour, Tousi Maryam. "Electric Field Grading and Electrical Insulation Design for High Voltage, High Power Density Wide Bandgap Power Modules." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100621.
Повний текст джерелаАнотація:
The trend towards more and all-electric apparatuses and more electrification will lead to higher electrical demand. Increases in electrical power demand can be provided by either higher currents or higher voltages. Due to "weight" and "voltage" drop, a raise in the current is not preferred; so, "higher voltages" are being considered. Another trend is to reduce the size and weight of apparatuses. Combined, these two trends result in the high voltage, high power density concept. It is expected that by 2030, 80% of all electric power will flow through "power electronics systems". In regards to the high voltage, high power density concept described above, "wide bandgap (WBG) power modules" made from materials such as "SiC and GaN (and, soon, Ga2O3 and diamond)", which can endure "higher voltages" and "currents" rather than "Si-based modules", are considered to be the most promising solution to reducing the size and weight of "power conversion systems". In addition to the trend towards higher "blocking voltage", volume reduction has been targeted for WBG devices. The blocking voltage is the breakdown voltage capability of the device, and volume reduction translates into power density increase. This leads to extremely high electric field stress, E, of extremely nonuniform type within the module, leading to a higher possibility of "partial discharge (PD)" and, in turn, insulation degradation and, eventually, breakdown of the module. Unless the discussed high E issue is satisfactorily addressed and solved, realizing next-generation high power density WBG power modules that can properly operate will not be possible. Contributions and innovations of this Ph.D. work are as follows. i) Novel electric field grading techniques including (a) various geometrical techniques, (b) applying "nonlinear field-dependent conductivity (FDC) materials" to high E regions, and (c) combination of (a) and (b), are developed; ii) A criterion for the electric stress intensity based upon accurate dimensions of a power device package and its "PD measurement" is presented; iii) Guidelines for the electrical insulation design of next-generation high voltage (up to 30 kV), high power density "WBG power modules" as both the "one-minute insulation" and PD tests according to the standard IEC 61287-1 are introduced; iv) Influence of temperature up to 250°C and frequency up to 1 MHz on E distribution and electric field grading methods mentioned in i) is studied; and v) A coupled thermal and electrical (electrothermal) model is developed to obtain thermal distribution within the module precisely. All models and simulations are developed and carried out in COMSOL Multiphysics.Doctor of Philosophy
In power engineering, power conversion term means converting electric energy from one form to another such as converting between AC and DC, changing the magnitude or frequency of AC or DC voltage or current, or some combination of these. The main components of a power electronic conversion system are power semiconductor devices acted as switches. A power module provides the physical containment and package for several power semiconductor devices. There is a trend towards the manufacturing of electrification apparatuses with higher power density, which means handling higher power per unit volume, leading to less weight and size of apparatuses for a given power. This is the case for power modules as well. Conventional "silicon (Si)-based semiconductor technology" cannot handle the power levels and switching frequencies required by "next-generation" utility applications. In this regard, "wide bandgap (WBG) semiconductor materials", such as "silicon carbide (SiC)"," gallium nitride (GaN)", and, soon, "gallium oxide" and "diamond" are capable of higher switching frequencies and higher voltages, while providing for lower switching losses, better thermal conductivities, and the ability to withstand higher operating temperatures. Regarding the high power density concept mentioned above, the challenge here, now and in the future, is to design compact WBG-based modules. To this end, the extremely nonuniform high electric field stress within the power module caused by the aforementioned trend and emerging WBG semiconductor switches should be graded and mitigated to prevent partial discharges that can eventually lead to breakdown of the module. In this Ph.D. work, new electric field grading methods including various geometrical techniques combined with applying nonlinear field-dependent conductivity (FDC) materials to high field regions are introduced and developed through simulation results obtained from the models developed in this thesis.
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Ertek, Talip Murat. "Speed Estimation Techniques For Sensorless Vector Controlled Induction Motor Drive." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606863/index.pdf.
Повний текст джерелаАнотація:
This work focuses on speed estimation techniques for sensorless closed-loop speed control of an induction machine based on direct field-oriented control technique. Details of theories behind the algorithms are stated and their performances are verified by the help of simulations and experiments.
The field-oriented control as the vector control technique is mainly implemented in two ways: indirect field oriented control and direct field oriented control. The field to be oriented may be rotor, stator, or airgap flux-linkage. In the indirect field-oriented control no flux estimation exists. The angular slip velocity estimation based on the measured or estimated rotor speed is required, to compute the synchronous speed of the motor. In the direct field oriented control the synchronous speed is computed with the aid of a flux estimator. Field Oriented Control is based on projections which transform a three phase time and speed dependent system into a two co-ordinate time invariant system. These projections lead to a structure similar to that of a DC machine control. The flux observer used has an adaptive structure which makes use of both the voltage model and the current model of the machine.
The rotor speed is estimated via Kalman filter technique which has a recursive state estimation feature. The flux angle estimated by flux observer is processed taking the angular slip velocity into account for speed estimation. For closed-loop speed control of system, torque, flux and speed producing control loops are tuned by the help of PI regulators. The performance of the closed-loop speed control is investigated by simulations and experiments. TMS320F2812 DSP controller card and the Embedded Target for the TI C2000 DSP tool of Matlab are utilized for the real-time experiments.
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Stefopoulos, Georgios Konstantinos. "Quadratic power system modeling and simulation with application to voltage recovery and optimal allocation of VAr support." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29695.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Taylor, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Parris, Joseph Steele. "Finite-Difference Time-Domain Modeling of Nickel Nanorods." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2707.
Повний текст джерелаАнотація:
Theoretical and experimental plasmonics is a growing field as a method to create near fields at sub-wavelength distances. In this thesis, a finite-difference time-domain method is used to simulate electromagnetic waves onto a thin film that present of nickel nanorods with sharp apexes. The absorbed, transmitted, and reflected fields were shown to depend linearly on silver film thickness and nanotip length. The electric field is visualized along the tip to show strong charge density along the base of the tip’s apex and how that density changes for wavelength, metal, and source tilt. Lastly, the study shows gold film on the nanotip apex provides the largest enhancement of the electric field for the wavelengths 532, 572, and 633 nm.
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Donets, Sergii [Verfasser], and Stephan [Akademischer Betreuer] Bäurle. "Development and application of field-based multiscale modeling techniques for optimizing the performance of polymer nanodevices / Sergii Donets. Betreuer: Stephan Bäurle." Regensburg : Universitätsbibliothek Regensburg, 2014. http://d-nb.info/1071713248/34.
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Ved, Hetal R. "A computer-based cascaded modeling and experimental approach to the physical characterization of a clinical full-field mammography system." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0920102-144012.
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Johnson, Buxton L. Sr. "HYBRID PARALLELIZATION OF THE NASA GEMINI ELECTROMAGNETIC MODELING TOOL." UKnowledge, 2017. http://uknowledge.uky.edu/ece_etds/99.
Повний текст джерелаАнотація:
Understanding, predicting, and controlling electromagnetic field interactions on and between complex RF platforms requires high fidelity computational electromagnetic (CEM) simulation. The primary CEM tool within NASA is GEMINI, an integral equation based method-of-moments (MoM) code for frequency domain electromagnetic modeling. However, GEMINI is currently limited in the size and complexity of problems that can be effectively handled. To extend GEMINI’S CEM capabilities beyond those currently available, primary research is devoted to integrating the MFDlib library developed at the University of Kentucky with GEMINI for efficient filling, factorization, and solution of large electromagnetic problems formulated using integral equation methods. A secondary research project involves the hybrid parallelization of GEMINI for the efficient speedup of the impedance matrix filling process. This thesis discusses the research, development, and testing of the secondary research project on the High Performance Computing DLX Linux supercomputer cluster. Initial testing of GEMINI’s existing MPI parallelization establishes the benchmark for speedup and reveals performance issues subsequently solved by the NASA CEM Lab. Implementation of hybrid parallelization incorporates GEMINI’s existing course level MPI parallelization with Open MP fine level parallel threading. Simple and nested Open MP threading are compared. Final testing documents the improvements realized by hybrid parallelization.
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Haas, Benedikt. "Développement de techniques quantitatives en microscopie électronique à balayage en transmission." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY018/document.
Повний текст джерелаАнотація:
Dans cette thèse, différentes techniques de microscopie électronique à transmission et à balayage (STEM : scanning transmission electron microscopy) ont été améliorées et appliquées à plusieurs structures essentiellement à base de semiconducteurs. La création de nouveaux matériaux et dispositifs a été à l'origine du développement des civilisations et des méthodes de caractérisation expérimentales sont nécessaires pour étudier les nouvelles structures afin de les comprendre et de les améliorer. Avec le développement des nanotechnologies, la microscopie électronique est devenu un outil indispensable du fait de sa grande résolution spatiale et de la pléthore d'information qu'elle permet d'obtenir.Dans la première partie de cette thèse, les nombreux développements réalisés sont présentés. Plusieurs sous-techniques du STEM ont été améliorés : création de moirés obtenus par balayage (SMF : scanning moiré fringes), nano-diffraction électronique en mode précession (NPED : nano-beam precession diffraction) et haute résolution en STEM (HR-STEM). Ces développements permettent d'obtenir des cartographies quantitatives sur les déformations et les champs électriques et indirectement des informations chimiques.Dans la deuxième partie, les techniques développés sont utilisés pour étudier différentes structures et les résultats sont comparés à ceux d'autres techniques comme l'holographie et le contraste de phase différentielle (DPC : differentail phase contrast). Dans une structure photovoltaïque à base de matériaux II-VI, une accumulation d'un matériau II a été détectée aux interfaces grâce aux mesures des déformations. Des champs de déformations très faibles capitaux pour le fonctionnement des isolants topologiques à base de HgTe ont été mesurés. Des cartographies de déformation très précises ont été obtenues dans des transistors SiGe. Dans des couches AlN/GaN des cartographies de déformation et de champs électriques ont pu être réalisés simultanément révélant l'importance des dislocations. Des domaines d'inversion coeur-coquille ont été mis en évidence pour la première fois. Ils ont été observés dans de nombreux fils de GaN élaborés par épitaxie par jet moléculaires. Les positions des atomes dans un domaine d'inversion ont pu être mesurés à quelques picomètres près et comparés à des calculs ab-initioIn this work, different scanning transmission electron microscopy (STEM) techniques have been developed and applied to several material systems. The creation of novel materials and devices has been a backbone of society’s development and characterization methods are needed to investigate these materials in order to understand and improve them. With the advent of nanotechnology, electron microscopy has become an invaluable tool, as it is able to visualize the atomic structure of thin samples and produces a plethora of quantifiable signals.In a first part, the numerous developments realized in this thesis are presented. Several STEM based techniques have been improved: scanning moiré fringes (SMF), nano-beam precession diffraction (NPED) and high-resolution STEM (HR-STEM). These developments allow for more accurate strain measurements, the quantitative mapping of electric fields and to realize accurate chemical profiles.In a second part, the developed methods are applied to different material systems and compared to more classical techniques, like holography and differential phase contrast (DPC). In a II/VI solar cell structure the interface chemistry is determined from strain with atomic resolution. Very faint strain gradients that are vital for the topological insulator properties of HgTe are measured. Accurate two-dimensional strain maps are obtained of a SiGe transistor. Simultaneous strain and electric field maps of m-plane AlN/GaN reveal the influence of dislocations in the material. Core-shell type inversion domains are described for the first time in GaN nanowires. They were found in many samples grown by molecular beam epitaxy. Thanks to quantitative analysis the exact atomic structure of inversion domains in GaN is described and compared to simulations
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Tarog, Emanuel S. "Design techniques to improve time dependent dielectric breakdown based failure for CMOS circuits." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/229.
Повний текст джерелаАнотація:
This project investigates the failure of various CMOS circuits as a result of Time Dependent Dielectric Breakdown (TDDB) and explores design techniques to increase the mean time to failure (MTTF) of large-scale circuits. Time Dependent Dielectric Breakdown is a phenomenon where the oxide underneath the gate degrades as a result of the electric field in the material. Currently, there are few well documented design techniques that can increase lifetime, but with a tool chain I created called the MTTF Analyzing Program, or MAP, I was able to test circuits under various conditions in order to identify weak links, discover relationships, and reiterate on my design and see improvements and effects.
The tool chain calculates power consumption, performance, temperature, and MTTF for a 'real life' circuit. Electric VLSI, an Electronic Design Automation tool, outputs a Spice file that yields parasitic quantities and spatial dimensions. LTspice, a high performance Spice simulator, was used to calculate the voltage and current data. Finally, I created MAP to monitor the voltage, current, and dimension data and process that in conjunction with HotSpot, a thermal modeling tool, to calculate a MTTF for each MOSFET.
Analysis of the data from the software infrastructure showed that transistor sizing played a role in the MTTF. To maximize the MTTF of a transistor in a CMOS inverter, the activity of the pull-up transistor should be balanced with the transistor in the pull-down chain, ensuring the electric fields are balanced across both transistors. While it is impossible to completely balance an arbitrary CMOS circuit's activity for an arbitrary set of input signals, circuits can be intelligently skewed to help maximize the MTTF without increasing power consumption and without sacrificing circuit performance. Consequently, attaining a maximum MTTF does not come at a cost as it is possible to design a circuit with a high MTTF that performs better and uses less power than a circuit with low MTTF.
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Lim, Tien Tze. "Molecular characterization of Malaysian methicillin-resistant Staphylococcus aureus." Curtin University of Technology, School of Biomedical Sciences, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17817.
Повний текст джерелаАнотація:
Seventy-four methicillin-resistant Staphylococcus aureus (MRSA) from two Malaysian hospitals were characterised by both phenotypic and genotypic techniques. These isolates were collected over an 18 year time period in the years, 1982, 1989, 1994 and 2000. All of the Malaysian MRSA isolates were found to be multiresistant and resistant to at least five different antimicrobial agents. Over 30% of them were non-typable by the International Basic Set of bacteriophages. The majority of the typable isolates were susceptible to the group III phages, especially phage 85. The majority of the isolates carried one to six plasmids. Only two isolates were plasmid free. The plasmid profiles of these isolates, other than the 1982 isolates, were very similar to each other. Contour-clamped homogeneous electric field (CHEF) gel electrophoresis was used to examine the genetic relatedness of the isolates. Twenty-six CHEF patterns were found among the isolates. These CHEF patterns were closely related to each other. The predominant CHEF pattern A was found in the 1982, 1989 and 1994 isolates. The CHEF patterns of the year 2000 isolates were different to CHEF pattern A, but still closely related. All of the isolates were found to carry the Allotype III SCCmec and have coagulase-gene type 24. Multilocus sequence typing was preformed on the isolates with CHEF pattern A collected in different years. These isolates were found to have either sequence type 239 (ST239), or its single locus variant. The predominant Malaysian clone belongs to the pandemic clone ST239-MRSA-III that is pandemic in Asian countries. (Enright, 2003, Ko et al., 2005).A 1.5 kb cryptic plasmid found in Malaysian isolates was indistinguishable from a cryptic plasmid found in an Australian isolate. A 3.0 kb cryptic plasmid found in Malaysian isolates was undistinguishable from a 3.0 kb plasmid found in Singaporean isolates. Class II multiresistance plasmids of 28, 30.5 and 35 kb were commonly found together in many Malaysian MRSA isolates. Both the 28 and 30.5 kb plasmids encode resistance to the heavy-metals and nucleic acid-binding (NAB) compounds. The 35 kb plasmid carries heavy-metal and NAB resistance but also encodes β-lactamase. Structurally these three plasmids are almost identical and probably have the same origin. The differences observed between these plasmids is probably due to excision or partial deletion of the β-lactamase transposon of the original plasmid. The 28 kb plasmid is identical to the 28 kb plasmid of Singaporean and some Australian isolates. A 20 kb plasmid in Indonesian isolates was found to be closely related to these three plasmids. A conjugative plasmid, pWBG707, conferring trimethoprim-resistance was found in Malaysian isolates. It did not carry either of the two staphylococcal trimethoprim-resistance genes, dfrA and dfrD. (Lyon and Skurray, 1987, Dale et al., 1995b) It either encodes a novel resistance gene or the recently discovered dfrG gene. (Sekiguchi et al., 2005) pWBG707 was also found to mobilise a small 3.0 kb kanamycin-resistance plasmid during conjugation.
The mecR1 and mecI genes regulating the transcription of the methicillin-resistance gene, mecA, were also examined in the isolates. The Malaysian isolate, WBG7422, with the predominant CHEF pattern A has a nonsense mutation in its mecI gene that disables it. However, its mecR1 gene is intact. The eastern Australia MRSA (EA MRSA), WBG525, has a CHEF pattern that is closely related to the Malaysian predominant CHEF pattern A and its mecI gene has a mutation identical to the Malaysian isolate. Unlike the Malaysian isolate however, its mecR1 gene has a 166 bp deletion. Both WBG7422 and WBG525 express Class III heterogeneous methicillin resistance. However, WBG525 has more highly resistant cell in its population than WBG7422. The loss of aminoglycoside resistance, together with c. 114 kb of chromosomal DNA, was observed in some Malaysian isolates. The deleted segment was found to carry the aacA-aphD gene that encodes a bifunctional aminoglycoside-modifying enzyme conferring resistance to many of the aminoglycosides. The Malaysian isolates were compared with MRSA from different countries. These MRSA included 18 epidemic MRSA (EMRSA) from the United Kingdom, 15 Australian nosocomial MRSA, five classical MRSA, 22 community-acquired MRSA (CMRSA) from Australia and New Zealand and 46 nosocomial MRSAs from eight Asian-Pacific countries and South Africa. These Asian-Pacific countries were Australia, PR China, Hong Kong, Indonesia, Japan, Philippines, Singapore and Taiwan.
The CHEF patterns of most of the Asian-Pacific and South African isolates were closely related to the Malaysian isolates. Isolates from Singapore, Indonesia and Philippines were found to have an identical CHEF pattern to the Malaysian CHEF patterns A5. The Asian-Pacific and South African isolates, including the Malaysian isolates, were found to be closely related to EMRSA-1, -4 and -7. These EMRSA belong to the ST239-MRSA-III clone and are coagulase-gene type 24. The isolates from Japan were the only Asian-Pacific isolates not related to the other Asian-Pacific isolates and EMRSAs. EMRSA-1 and EA MRSA have the same 166 bp deletion in their mecR1 gene. Both of these strains have closely related CHEF patterns, the same sequence type, coagulase-gene type and SCCmec. These results indicate that these two strains belongs to the same clone and confirms the international spread of this clone in the early 1980s. However, the Malaysian isolates have CHEF patterns that are more closely related to EMRSA-4 than to EMRSA-1. Similar to the Malaysian isolates EMRSA-4 has an intact mecR1 gene. The CMRSA isolates were not related to any of the nosocomial MRSA. They also have very diverse genetic backgrounds but carry less diverse SCCmec allotypes. Most of the CMRSA carry either Allotype IV or V SCCmec These results show that the spread of Malaysian MRSA is due to a single clonal expansion. Infection control measures would have to have been more efficient if this clone was to have been contained. The Malaysian epidemic clone is the Asian pandemic clone, ST239-MRSA-III. The Malaysian isolates and EMRSA-4 probably share the same ancestor.
The presence of the same MRSA strain in Malaysian hospitals and in the hospitals of neighbouring countries indicates that the inter-hospital spread of an epidemic MRSA has occurred. This observation also suggests that the infection control measures in Malaysian hospitals have not been totally effective. The ineffectiveness of infection control has left Malaysian hospitals vulnerable to the future importation of new pandemic clones and/or highly virulent or resistant clones.
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Paramonov, Pavel B. "Theoretical Modeling of the Nanostructure Formation in Soft Condensed Matter Using Atomic Force Microscopy." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1123016038.
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Belhi, Memdouh. "Simulation numérique de l’effet de champ électrique sur la stabilité des flammes de diffusion." Thesis, Rouen, INSA, 2012. http://www.theses.fr/2012ISAM0007/document.
Повний текст джерелаАнотація:
L'application de champ électrique est connue pour avoir la capacité d'améliorer significativement la stabilité des flammes. A ce sujet, un modèle mathématique permettant de modéliser la combustion en présence d'un champ électrique a été développé. Les équations de l'aérothermochimie sont couplées à des équations de bilan pour les densités des espèces chargées, et une équation de Poisson pour le potentiel électrique est résolue. Une situation principale est étudiée pendant la thèse ; elle concerne la stabilisation de flammes de diffusion par application d’un champ électrique continu ou alternatif.Les résultats obtenus montrent que la présence du champ électrique améliore significativement la stabilisation de la flamme. L’ampleur de cette amélioration dépend de l’intensité et de la polarité de la tension appliquée. Si la tension appliquée est alternative, un facteur supplémentaire s’ajoute pour influencer la stabilisation ; il s’agit de la fréquence. Une interprétation des mécanismes permettant la stabilisation est proposéeThe application of electric field is known to have the ability to improve significantly the flame stability. In this regard, a mathematical approach to model combustion in the presence of an electric field was developed. The Navier-Stokes equations along with transport equations for charged species and the electric potential Poisson’s equation are solved. A main situation, that concerns the stabilization of diffusion flames by applying a direct or alternating electric field, is studied. The results show that the presence of the electric field improves the flame stabilization. The magnitude of this improvement depends on the intensity and polarity of the applied voltage. If the applied voltage is alternating, an additional factor, which is the frequency of the electric current, influences also the extent of the flame stabilization improvement. An interpretation of the stabilization mechanisms is proposed
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Stefan, Anca Irina. "Modeling and design of resonators for electron paramagnetic resonance imaging and ultra high field magnetic resonance imaging." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133293403.
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Mieskoski, Randy. "Capturing and Modeling a Three-Dimensional Stationary Noise Source Directivity Pattern with a Dynamic Array in the Near Field." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1387979181.
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LOPES, Diego Soares. "Modelo de elementos finitos aplicado na avaliação de desempenho de isolantes em ambientes contaminados." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/19497.
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A presente dissertação aplica um modelo computacional para mapeamento da distribuição de potencial e campo elétrico ao longo de dispositivos isolantes na presença de uma camada condutiva em sua superfície. Na natureza, a formação dessa camada se dá através da deposição de poluição juntamente com a umidade ambiental. A pesquisa teve como base outros estudos presentes na literatura que abordam a mesma temática. A avaliação do comportamento da distribuição de potencial e campo elétrico em peças isolantes é de fundamental importância na determinação de possíveis regiões, as quais esses dispositivos apresentem maior estresse elétrico, tais regiões podem levar a descargas parciais e possíveis desgastes dos acessórios levando assim à sua falha. O modelo aplicado foi implementado utilizando o MEF (Método dos Elementos Finitos) através da construção do ambiente nosoftwareCOMSOLMultiphysicse da representação gráfica do acessório noAutoCAD. O estudo foi realizado em isoladores de vidro e polimérico, bem como em espaçadores, sob diferentes níveis de poluição. Os resultados obtidos são coerentes e apresentam consonância com a teoria envolvida neste estudo.
This dissertation applies a computational model to map the voltage distribution and electric field along dielectric devices in presence of a thin conductive layer on its surface. In the nature this thin layer may appear due to pollution deposition with environmental humidity. The base of this research are another studies found in literature with the same theme. The behavior of voltage distribution and electric field in dielectric devices has significant importance helping to determine possible regions where this devices present higher stress levels, causing partial discharges and possible damage to the accessories leading them to a failure condition. The applied model was implemented using FEM (finite element method) building an environment in COMSOL Multiphysics software and graphically representing each accessory through using AutoCAD. The present study was done in insulators made of glass and polymer, as well as spacers, under several pollution levels. The obtained results are consistent and show consonance with the whole theory involved in this research.
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Urban, Ferdinand. "Termodynamické poměry ve zhášedle výkonového vypínače NN." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233464.
Повний текст джерелаАнотація:
Práce se zabývá studiem procesů probíhajících při zhášení silnoproudého oblouku ve zhášecí komoře jističe. Je zaměřena na výpočet dynamiky tekutin a teplotního pole v okolí elektrického oblouku. V práci je dále popsán vliv vzdálenosti plechů v komoře a vliv tvarů plechů z hlediska aerodynamických podmínek uvnitř komory. Dalším cílem dosaženým touto prací je poskytnutí informací o vlivu polohy elektrického oblouku na termodynamické vlastnosti uvnitř komory. Toto je důležité, zejména pokud je oblouk do komory vtahován jinými silami, např. elektromagnetickými a během tohoto vtahovacího procesu mění svůj tvar i polohu. Za účelem co nejjednoduššího, ale zároveň co nejefektivnějšího řešení úkolu, byl vyvinut software určen speciálně pro výpočet dynamiky tekutin numerickou metodou konečných objemů (FVM). Tato metoda je, v porovnání s rozšířenější metodou konečných prvků (FEM), vhodnější pro výpočet dynamiky tekutin (CFD) zejména proto, že režie na výpočet jedné iterace jsou menší v porovnání s ostatními numerickými metodami. Další výhodou tohoto softwarového řešení je jeho modularita a rozšiřitelnost. Cely koncept softwaru je postaven na tzv. zásuvných modulech. Díky tomuto řešení můžeme využít výpočtové jádro pro další numerické analýzy, např. strukturální, elektromagnetickou apod. Jediná potřeba pro úspěšné používání těchto analýz je napsáni solveru pro konečné prvky (FEM). Jelikož je software koncipován jako multi–thread aplikace, využívá výkon současných vícejádrových procesorů naplno. Tato vlastnost se ještě více projeví, pokud se výpočet přesune z CPU na GPU. Jelikož současné grafické karty vyšších tříd mají několik desítek až stovek výpočetních jader a pracují s mnohem rychlejšími pamětmi, než CPU, je výpočetní výkon několikanásobně vyšší.
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Schoene, Jens. "Analysis of parameters of rocket-triggered lightning measured during the 1999 and 2000 Camp Blanding experiment and modeling of electric and magnetic field derivatives using the transmission line model." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE1000160.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Florida, 2002.Title from title page of source document. Document formatted into pages; contains viii, 184 p.; also contains graphics. Includes vita. Includes bibliographical references.
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Han, Ki Jin. "Electromagnetic modeling of interconnections in three-dimensional integration." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29642.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Madhavan Swaminathan; Committee Member: Andrew E. Peterson; Committee Member: Emmanouil M. Tentzeris; Committee Member: Hao-Min Zhou; Committee Member: Saibal Mukhopadhyay. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Baimpas, Nikolaos. "'Hybrid' non-destructive imaging techniques for engineering materials applications." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1aa00fed-34e6-4a5e-951b-c710e21ac23c.
Повний текст джерелаАнотація:
The combination of X-ray imaging and diffraction techniques provides a unique tool for structural and mechanical analysis of engineering components. A variety of modes can be employed in terms of the spatial resolution (length-scale), time resolution (frequency), and the nature of the physical quantity being interrogated. This thesis describes my contributions towards the development of novel X-ray “rich” imaging experimental techniques and data interpretation. The experimental findings have been validated via comparison with other experimental methods and numerical modelling. The combination of fast acquisition rate and high penetration properties of X-ray beams allows the collection of high-resolution 3-D tomographic data sets at submicron resolution during in situ deformation experiments. Digital Volume Correlation analysis tools developed in this study help understand crack propagation mechanisms in quasi-brittle materials and elasto-plastic deformation in co-sprayed composites. For the cases of crystalline specimens where the knowledge of “live” or residual elastic strain distributions is required, diffraction techniques have been advanced. Diffraction Strain Tomography (DST) allows non-destructive reconstruction of the 2-D (in-plane) variation of the out-of-plane strain component. Another diffraction modality dubbed Laue Orientation Tomography (LOT), a grain mapping approach has been proposed and developed based on the translate-rotate tomographic acquisition strategy. It allows the reconstruction of grain shape and orientation within polycrystalline samples, and provides information about intragranular lattice strain and distortion. The implications of this method have been thoroughly investigated. State-of-the-art engineering characterisation techniques evolve towards scrutinising submicron scale structural features and strain variation using the complementarity of X-ray imaging and diffraction. The first successful feasibility study is reported of in operando stress analysis in an internal combustion engine. Finally, further advancement of ‘rich’ imaging techniques is illustrated via the first successful application of Time-of-Flight Neutron Diffraction Strain (TOF-NDST) tomography for non-destructive reconstruction of the complete strain tensor using an inverse eigenstrain formulation.
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Jaiswal, Vinay Kumar. "Finite element modeling of electric field distributions around a resistive glazed post station insulator covered with ice = Modélisation par éléments finis de la distribution du champ électrique autour d'un isolateur de poste avec une couche semi-conductrice recouvert de glace /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2005. http://theses.uqac.ca.
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Веселов, М. О. "Адаптація можливостей MATLAB Simulink для моделювання режимів роботи електричних мереж 0,4-110 кВ". Thesis, Чернігів, 2021. http://ir.stu.cn.ua/123456789/25263.
Повний текст джерелаАнотація:
Веселов, М. О. Адаптація можливостей MATLAB Simulink для моделювання режимів роботи електричних мереж 0,4-110 кВ : випускна кваліфікаційна робота : 141 "Електроенеретика, електротехніка та електромеханіка" / М. О. Веселов ; керівник роботи Р. О. Буйний ; НУ "Чернігівська політехніка", кафедра електричної інженерії та інформаційно-вимірювальних технологій. – Чернігів, 2021. – 81 с.Об’єктом дослідження є моделювання режимів роботи електричних мереж 0.4 - 110 кВ. Предмет дослідження – адаптація можливостей програмного пакету MATLAB Simulink для моделювання режимів роботи електричних мереж. Мета роботи – зменшення витрат часу на створення моделей електричних мереж та введення даних в модель в MATLAB Simulink та зменшення розмірів моделей. Практичне значення – створені моделі можуть бути використані для моделювання режимів роботи електричних мереж.
The object of research is the modeling of 0.4 - 110 kV electrical networks. The subject of research is the possibility of modeling the modes of operation of electrical networks in the software package MATLAB Simulink. The purpose of the work is to reduce the time spent on creating models of electrical networks and data entry into the model in MATLAB Simulink and reduce the size of models. Practical significance - the created models can be used to model the modes of operation of electrical networks.
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Сосіна, Олена Володимирівна. "Визначення співвідношень параметрів елементів конструкцій об'єктів електричних систем для зниження коронування". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/20292.
Повний текст джерелаАнотація:
Дисертація на здобуття вченого ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2016. Дисертаційна робота присвячена вирішенню актуальної наукової задачі визначення співвідношень між висотою та радіусами округлень кромок елементів конструкцій об'єктів електричних систем для зниження на них процесів коронування. У дисертаційній роботі описано вдосконалений метод оцінки величини струму корони по розрахованому електричному полі і знайденому об'єму зон, в яких рівні напруженості електричного поля перевищують або дорівнюють пробивній напруженості. У роботі запропонований метод врахування криволінійної границі розділу провідного та непровідного середовищ при накладенні прямокутної розрахункової сітки, заснований на знаходженні площин криволінійних поверхонь, які знаходяться всередині комірок розрахункової сітки, а також відстаней між криволінійною поверхнею і вузлами сітки. Отримано вираз, що дозволяє розрахувати величини критичної напруженості електричного поля, при прикладенні якого на стрижнях певної висоти і радіусу округлення вершин виникають коронні розряди. Визначені співвідношення між радіусами округлення вершин стрижневих електродів і їх висотою, при яких коронні розряди відсутні або їх інтенсивність суттєво знижується (на порядок і більше).Thesis for scientific degree of candidate of technical sciences, specialty 05.14.02 – Еlectrical power stations, nets and systems. – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2016. Dissertation work is devoted to the solution of an actual scientific and applied research problem of development of methods of mathematical and physical model operation of the electromagnetic processes accompanying formation of a crown on sharp edges of elements of electrical power systems, and a choice with their help of geometrical parameters of the objects providing suppression or decrease in intensity of a corona process. In dissertation work the advanced method of an assessment of size of current of a crown on the calculated electric field and the found volume of zones in which levels of an electric intensity exceed is described or are equal to penetrative strength. In work the method of the accounting of a curvilinear demarcation of conductive and nonconducting environments when imposing a rectangular calculated grid based on finding of lengths of the curvilinear surfaces concluded in cells of a calculated grid, and also distances between a curvilinear surface and clusters of a grid is offered. The expression allowing to calculate sizes of a critical electric intensity at which appendix on rod stock of a particular height and radius of a rounding off of tops there are corona discharges is received. Ratios between diameters of a rounding off of tops of rod electrodes and their height with which corona discharges do not arise are defined.
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Mao, Jifeng. "Modeling of simultaneous switching noise in on-chip and package power distribution networks using conformal mapping, finite difference time domain and cavity resonator methods." Diss., Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-10062004-125025/.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.Madhavan Swaminathan, Committee Chair ; Sung Kyu Lim, Committee Member ; Abhijit Chatterjee, Committee Member ; David C. Keezer, Committee Member ; C. P. Wong, Committee Member. Vita. Includes bibliographical references.
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Сосіна, Олена Володимирівна. "Визначення співвідношень параметрів елементів конструкцій об'єктів електричних систем для зниження коронування". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/20290.
Повний текст джерелаАнотація:
Дисертація на здобуття вченого ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2016.
Дисертаційна робота присвячена вирішенню актуальної наукової задачі визначення співвідношень між висотою та радіусами округлень кромок елементів конструкцій об'єктів електричних систем для зниження на них процесів коронування. У дисертаційній роботі описано вдосконалений метод оцінки величини струму корони по розрахованому електричному полі і знайденому об'єму зон, в яких рівні напруженості електричного поля перевищують або дорівнюють пробивній напруженості. У роботі запропонований метод врахування криволінійної границі розділу провідного та непровідного середовищ при накладенні прямокутної розрахункової сітки, заснований на знаходженні площин криволінійних поверхонь, які знаходяться всередині комірок розрахункової сітки, а також відстаней між криволінійною поверхнею і вузлами сітки. Отримано вираз, що дозволяє розрахувати величини критичної напруженості електричного поля, при прикладенні якого на стрижнях певної висоти і радіусу округлення вершин виникають коронні розряди. Визначені співвідношення між радіусами округлення вершин стрижневих електродів і їх висотою, при яких коронні розряди відсутні або їх інтенсивність суттєво знижується (на порядок і більше).Thesis for scientific degree of candidate of technical sciences, specialty 05.14.02 – Еlectrical power stations, nets and systems. – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2016. Dissertation work is devoted to the solution of an actual scientific and applied research problem of development of methods of mathematical and physical model operation of the electromagnetic processes accompanying formation of a crown on sharp edges of elements of electrical power systems, and a choice with their help of geometrical parameters of the objects providing suppression or decrease in intensity of a corona process. In dissertation work the advanced method of an assessment of size of current of a crown on the calculated electric field and the found volume of zones in which levels of an electric intensity exceed is described or are equal to penetrative strength. In work the method of the accounting of a curvilinear demarcation of conductive and nonconducting environments when imposing a rectangular calculated grid based on finding of lengths of the curvilinear surfaces concluded in cells of a calculated grid, and also distances between a curvilinear surface and clusters of a grid is offered. The expression allowing to calculate sizes of a critical electric intensity at which appendix on rod stock of a particular height and radius of a rounding off of tops there are corona discharges is received. Ratios between diameters of a rounding off of tops of rod electrodes and their height with which corona discharges do not arise are defined.