Dissertations / Theses on the topic 'Forced component of current'

В представленій роботі було розроблено компенсатор длякомпенсації реактивної потужності в перехідних режимах. На основі аналізу, узагальнення й систематизації наукових джерел висвітлено огляд основних способів компенсації реактивної потужності. Оцінюються переваги та недоліки окремих видів компенсації. Розглянуто методи компенсації для різних типів перехідних процесів. Числові розрахунки та моделювання проводились з використанням програмних засобів MATLAB (пакет Simulink), MathCAD. Результатом роботи є розроблена модель пристрою компенсації реактивної потужності в перехідних режимах. Оцінено підвищення коефіцієнту потужності при використанні запропонованого алгоритму компенсації. Запропонований алгоритм компенсації в перехідних режимах дозволяє покращити параметри якості електроенергії мінімум на 5%. Результат роботи може бути використаний при розробці пристроїв компенсації в усталених і перехідних режимах.
In the present thesis project was developed compensator for the compensation of reactive power in transient conditions. Based on the analysis, synthesis and systematization of scientific sources, an overview of the main methods of reactive power compensation is highlighted. The advantages and disadvantages of certain types of compensation are assessed. Compensation methods for various types of transient processes are considered. Numerical calculations and modeling were carried out using software tools MATLAB (Simulink package), MathCAD. The result of the work is a developed model of a device for reactive power compensation in transient conditions. Estimated increase in power factor when using the proposed compensation algorithm. The proposed compensation algorithm in transient conditions allows to improve the quality parameters of electricity by at least 5%. The result of the work can be used in the development of compensation devices in established and transient modes.
В представленной работе был разработан компенсатор для компенсации реактивной мощности в переходных режимах. На основе анализа, обобщения и систематизации научных источников освещены обзор основных способов компенсации реактивной мощности. Оцениваются преимущества и недостатки отдельных видов компенсации. Рассмотрены методы компенсации для различных типов переходных процессов. Числовые расчеты и моделирование проводились с использованием программных средств MATLAB (пакет Simulink), MathCAD. Результатом работы является разработанная модель устройства компенсации реактивной мощности в переходных режимах. Оценен повышения коэффициента мощности при использовании предложенного алгоритма компенсации. Предложенный алгоритм компенсации в переходных режимах позволяет улучшить параметры качества электроэнергии минимум на 5%. Результат работы может быть использован при разработке устройств компенсации в устоявшихся и переходных режимах.

Application specific digital systems, called embedded systems, touch almost every aspect of modern human life. As a result, there is considerable interest in automating the design (called synthesis) of these systems. Further, given the time-to-market pressures and increasing system complexities, component reuse during synthesis is being touted as a key to success. This thesis proposes a formal framework for reusing system-level components during synthesis. Within the framework for component reuse, component matching is a key problem that must be addressed. Given the specification of a design function, and a device stored as a component in a library, component matching addresses the question of whether the device can implement the function. Often system-level components are multi-functional and generic, and it is rarely the case that the function is directly realizable by a device. Hence, an important aspect of matching is to decide whether the device can be dynamically adapted to match the function. This thesis proposes a formalization of the matching problem using formal models of the function and device, denoted by F and D respectively. D matches F provided there exists an interface I that adapts D dynamically to produce the same behaviour as F. None of the existing implementation verification techniques within formal methods can be used to test for the existence of an I between arbitrary pairs of F and D. In this thesis, a new simulation relation called forced simulation is proposed between the states of F and D. It is then formally established that the existence of a forced simulation relation is a necessary and sufficient condition for the existence of I for a pair of F and d. Two kinds of forced simulation are proposed, one each for synchronous and asynchronous interactions with the environment. Based on forced simulation, a polynomial time algorithm for automatic matching of F and D is also developed. The distinguishing feature of the algorithm is that when successful, it generates an interface that automatically adapts the device to behave like the function. The algorithm is illustrated by reusing two rogrammable components from Intel and some typical embedded controllers.

In an investigation of the process termed hydraulic vapour compression (HVC), a photographic study of bubble compression and condensation rates in single component co-current downflow has been performed. Supplemental to the photographic study, measurements of the deliverable mass flowrates of the HVC process were also carried out. The downward flow of a gas and liquid mixture, as occurs in the HVC process, results in the compression of the gas phase because of the increasing hydraulic pressure. Bubble compression heating provides the driving temperature difference for both heat and mass transfer to occur. The minimization of the transfer processes is desirable to ensure a high compression efficiency. Experiments were carried out using near saturated Freon-11 in a 2.54 cm I.D., 1.7 m long glass downcomer. Bubbles were filmed during travel along the downcomer. Histories of the decrease in individual bubble size were determined from silhouette traces obtained from sequenced single frames selected from the exposed films. Bubble volumes and surface areas were inferred by numerically revolving digitized images of the traces about their principal centroidal axes. The inferred volumes and surface areas provided the basis upon which heat and mass transfer rates were calculated. Delivered vapour mass flowrates were measured by hot film anemometry. Results showed that mass condensation rates increased along the length of the downcomer. Local external Nusselt numbers used to characterize the transfer processes at the bubble wall, ranged from 0.1 to 16. The deliverable mass flowrates achieved by the HVC process were found to be comparable to those produced by the well known process of hydraulic air compression.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

La miniaturisation de la structure de transistor MOS a conduit à l'amincissement de l'oxyde de grille. Ainsi, la dégradation et le claquage sous contrainte électrique est devenu l'un des problèmes de fiabilité les plus importants des couches minces d'oxydes. L'utilisation de techniques de caractérisation permettant de mesurer les courants de fuite avec une résolution spatiale nanométrique a montré que le phénomène de claquage des oxydes est un phénomène très localisé. Le diamètre des "points chauds", des endroits où le courant de fuite est très élevé pour une tension appliquée continue, peut-être de quelques nanomètres uniquement. Ceci illustre pourquoi les méthodes de caractérisation avec une résolution spatiale à l'échelle nanométrique peuvent fournir des informations supplémentaires par rapport à la caractérisation classique macroscopique. Il y a deux instruments, dérivés de la microscopie à force atomique (AFM) qui peuvent être utilisés pour faire ce travail, soit le Tunneling Atomic Force Microscope (TUNA) ou le Conductive Atomic Force Microscope (C-AFM). Le mode TUNA qui est utilisé dans notre travail est capable de mesurer des courants très faibles variant entre 60 fA et 100 pA. Notre travail peut être divisé en deux thèmes principaux: - La caractérisation électrique des couches minces d'oxydes high-k (LaAlO3 et Gd2O3) à l'échelle nanométrique en utilisant le Dimension Veeco 3100 où nous avons montré que la différence de leurs techniques d'élaboration influe largement sur le comportement électrique de ces oxydes. - Les caractérisations électriques et physiques à l'échelle nanométrique des couches minces d'oxydes thermiques SiO2 sous différentes atmosphères, c.à.d. dans l'air et sous vide (≈ 10-6 mbar) en utilisant le microscope Veeco E-Scope. L'influence de l'atmosphère a été bien étudiée, où nous avons montré que les phénomènes de claquage des couches minces d'oxydes peuvent être fortement réduits sous vide surtout en l'absence du ménisque d'eau sur la surface de l'oxyde pendant les expériences. En utilisant les plusieurs modes de l'AFM, il a été démontré que l'existence de bosses anormales (hillocks) sur la surface de l'oxyde après l'application d'une tension électrique est une combinaison de deux phénomènes: la modification morphologique réelle de la surface de l'oxyde et la force électrostatique entre les charges piégées dans le volume de l'oxyde et la pointe de l'AFM. Selon les images du courant obtenues par AFM en mode TUNA, deux phénomènes physiques pour la création de ces hillocks ont été proposés: le premier est l'effet électro-thermique et la seconde est l'oxydation du substrat Si à l'interface Si/oxyde.

Approved for public release; distribution is unlimited
A high-resolution, multi-level, primitive equation ocean model is used to examine the response of an eastern boundary oceanic regime to both wind forcing and irregular coastline geometry. The focus of this study is the coastal region from 300 N to 42.50 N, a portion of the Canary Current System (CCS). To study the generation, evolution, and sustainment of the currents, meanders, eddies and filaments of the CCS, the model is forced from rest using seasonal climatological winds. To investigate - the role of irregular coastline geometry, the first experiment uses climatological wind forcing along an idealized "straightened" coastline, while the second experiment uses the same wind forcing along an irregular coastline. In both cases a surface current, undercurrent, meanders, eddies, and filaments are generated. The results obtained while using the irregular, rather than the idealized coastline, however, show preferred eddy generation locations as well as enhanced growth of meanders, eddies, and filaments. The features produced by the model are consistent with available observations of the CCS. The model results support the hypothesis that both wind forcing and irregular coastline geometry are important mechanisms in the generation of many of the observed features of the CCS

Magnetic Resonance Electrical Impedance Tomography (MREIT) algorithms using current density distribution have been proposed in the literature. The current density distribution can be determined by using Magnetic Resonance Current Density Imaging (MRCDI) technique. In MRCDI technique, all three components of magnetic flux density should be measured. Hence, object should be rotated inside the magnet which is not trivial even for small size objects and remains as a strong limitation to clinical applicability of the technique. In this thesis, 2D MRCDI problem is investigated in detail and an analytical relation is found between Bz, Jx and Jy. This study makes it easy to understand the behavior of Bz due to changes in Jx and Jy. Furthermore, a novel 2D MRCDI reconstruction algorithm using one component of B is proposed. Iterative FT-MRCDI algorithm is also implemented. The algorithms are tested with simulation and experimental models. In simulations, error in the reconstructed current density changes between 0.27% - 23.00% using the proposed algorithm and 7.41% - 37.45% using the iterative FT-MRCDI algorithm for various SNR levels. The proposed algorithm is superior to the iterative FT-MRCDI algorithm in reconstruction time comparison. In experimental models, the classical MRCDI algorithm has the best reconstruction performance when the algorithms are compared by evaluating the reconstructed current density images perceptually. However, the J-substitution algorithm reconstructs the best conductivity image by using J obtained from the proposed algorithm. Finally, the iterative FT-MRCDI algorithm shows the best performance when the reconstructed current density images are verified by using divergence theorem.

Much has been researched in South Africa about the trauma of losing one&rsquo
s home, one&rsquo
s community and rebuilding one&rsquo
s life in a new environment. Several books have been published tracking the lives of the forcibly removed and their responses to leaving District Six. My research focuses on a different group namely those who had been forcibly removed from the centre of Stellenbosch, called &ldquo
Die Vlakte&rdquo
during that time. Living and working with and among people who have experienced this removal, I was keen to research whether the impact of the trauma is currently 
manifesting in this specific community and if so, what the symptoms would be. This qualitative inquiry focuses on one particular individual, Mr. Hilton Biscombe. I selected him because he, who experienced the removal as a teenager, spent most of his later life determinedly collecting stories and documents relating to this incident. Mr. Biscombe is also the only person of whom I am aware who responded personally through compiling a book, making a DVD, writing poetry as well as an autobiography relating to this event. My inquiry into the ways trauma manifests in a narrative, will be based on two interviews: one conducted by a white man from the University of Stellenbosch thirty years after the event
and another interview, six years later, conducted by myself.Our understanding of trauma is usually associated with a death or injury or the possibility thereof, but it could also include the victim&rsquo
s response to extreme fear, serious harm or threat to 
family members. According to van der Merwe and Vienings, people also become traumatized when witnessing harm, physical violence or death or the sudden loss or destruction of a victim&rsquo
s home (van der Merwe &
Vienings, 2001). So the issue of trauma is not in question, nor the fact that forced removals cause trauma. I am exploring testimony in the form of interviews for possible current manifestations of this trauma thirty-six years down the line.

Approved for public release; distribution is unlimited
A high-resolution, multi-level, primitive equation ocean model is used to investigate the roles of wind forcing and irregular coastline geometry in the generation of currents, eddies, jets and filaments in the Canary Current System (CCS) from 30 to 42.5 deg N. To study the generation, evolution, and sustainment of the currents, eddies, jets and filaments in the CCS, the model is forced from rest using seasonal climatological winds and a realistic coastline. Results of the experiment show that wind forcing alone is capable of generating surface currents, undercurrents, meanders, eddies, and filaments. Preferred eddy generation locations, enhanced growth of meanders, eddies, and filaments are seen. The features produced by the model are consistent with available observations of the CCS

The Brazil Current (BC) is possibly one of the least studied western boundary currents (WBCs) in the world ocean. Its unique vertical structure makes this a different WBC in terms of velocity and transport. Although significant progress has been made over the last decade, the BC system variability within the Santos Bight (SB, 23°S-28°S) is very poorly understood despite its strategic role for Brazil in terms of energy. The BC thickens and changes its vertical structure and dynamical modal composition as it crosses the SB. As it enters the bight by trying to contour Cape Frio (Cf, 23°S), the BC is about 500 m deep. As the current leaves the bight south of Cape Santa Marta (CSM, 28°S) it is 1300 m. These differences in thickness and accompanying velocity vertical shear are due to the impinging branch of the intermediate South Equatorial Current (SEC) generating the so called Santos Bifurcation (SBi). We here investigate the subinertial variability of the BC system within the SB primarily using satellite altimetry data and some traditional spectral analysis techniques. We also analyzed quasi-synoptic observations of an oceanographic cruise, which was part of the IOUSP-PETROBRAS CERES Experiment. We identified that there are different phenomena occurring to the north and to the south of the bifurcation and this might be caused by the SBi feature itself and/or the consequential change in the BC vertical structure downstream. North of the SBi, we detected oscillations with period of 92 days and a wavelength of 490 km and which represent about a fifth of the BC variability at 25°S. The 92-day oscillations are nonlinear vorticity waves, which are originated to the east of 35°W and propagate zonally towards the BC axis. These waves then perturb the current exciting oscillatory motions of the same period and which propagate downstream. South of the SBi axis (~28°S), we identified two different maxima in the ω - κ spectrum. They correspond to oscillations with periods (wavelengths) of 68 and 148 days (397 km and 790 km). The longer wave is also a baroclinic first-mode nonlinear vorticity waves propagating with westward phase speed of the nondispersive planetary Rossby waves of same period. They are originated in the ocean interior and we were able to track its signal as far as 5°W. The 68-day waves has its existence limited to vicinities of the BC. Phase speeds have approximately the BC axis orientation and they can only be clearly detected between ~27°S and ~32°S. This propagating signal accounts with a variance of ~21% on the BC axis. Quasi-synoptic observations allowed the mapping of a anticyclone and a cyclone of such waves. They seem to have modal composition very similar to the BC itself, which might provide additional evidence of local origin.
A Corrente do Brasil (CB) é provavelmente a Corrente de Contorno Oeste (CCO) menos estudada dos oceanos mundiais. A sua estrutura vertical única es faz dela uma CCO diferente em termos de velocidade e transporte. Apesar dos avanços significativos na última década, a variabilidade da CB na Bacia de Santos (BS, 23°S-28°S) ainda é pouco conhecida, apesar do papel estratégico da região na matriz energética brasileira. A CB se espessa mudando a sua estrutura vertical e muda sua estrutura dinâmica no domínio da BS. Na região de Cabo Frio (23°S) a corrente tem cerca de 500 m de profundidade. Ao sair da BS na região do Cabo de Santa Marta (28°S) a corrente se estende até cerca de 1300 m. Estas variações na espessura da corrente e consequente diferença no cisalhamento vertical de velocidade ocorrem devido à presença da Corrente Sul Equatorial em nível intermediário na região gerando a Bifurcação de Santos (BiS). Neste trabalho investigamos a variabilidade subinercial da CB na Bacia de Santos usando primeiramente dado alimétrico e um conjunto de análise espectral. Foram depois estudados fenômenos geradores dessa variabilidade com dados quasi-sinóticos do um cruzeiro oceanográfico CERES V do conjunto IOUSP-PETROBRAS. Foram identificados fenômenos diferentes no norte e sul da Bifurcação de Santos e esta diferença é provavelmente devido à presença da bifurcação ou à mudança que esta causa na estrutura da CB. Ao norte da BiS foi identificada uma oscilação com período de 92 dias e comprimento de onda de 490 km explicando um quinto da variabilidade da CB em 25°S. A oscilação de 92 dias está relacionada com ondas de vorticidade não lineares originadas a leste da corrente em ~35°W e se propagam zonalmente até ao eixo da corrente. Estas ondas perturbam a corrente originando oscilações com mesmo período e que propagam ao longo do eixo da corrente. Ao sul da BiS (~27°S) foram identificados dois máximos no espectro κ - ω. Os máximos correspondem a oscilações com período (comprimento de onda) de 68 e 148 dias (397 e 790 km). A onda com maior comprimento de onda é também uma onda de vorticidade de primeiro modo baroclínico não linear propagando para oeste com velocidade de fase de ondas de Rossby não dispersivas. Estas ondas são originadas no interior da bacia oceânica e seu sinal foi identificado chegando até 5°W. A onda de 68 dias existe apenas no domínio da CB. Esta onda propaga fase num eixo aproximadamente paralelo à CB e são detadas de forma clara apenas entre ~27°S e ~32°S. Esta onda explica uma variância da CB de ~21% ao longo do seu eixo. Observações quasi-sinóticas permitiram mapear um anticiclone e um ciclone associado a essa onda. Os vórtices aparentam uma estrutura modal muito semelhante à da corrente.

The forced expropriation has been, since the origins of the Peruvian Republic, a useful mechanism for the Government to meet its objectives, at the expense of the lawful damage inflicted to the private actors, conferring a fair compensation in return.In this article the current Peruvian legal regime of forced expropriation is studied, for which purpose both authors compare it with the regulation in the earliest Peruvian constitutions and laws, discovering that the concept has not always been designed in the same way by the constituent or the legislator.
La expropiación forzosa ha sido, desde los orígenes de la República, un mecanismo que ha servido al Estado para cumplir con sus objetivos, a costa del daño lícito causado al privado, y a cambio de un justiprecio. En el presente artículo se estudia el actual régimen jurídico de la expropiación forzosa en el Perú, para lo cual los autores lo comparan con lo regulado en las primeras constituciones y leyes peruanas, descubriendo que la figura no siempre fue pensada de la misma manera por el constituyente o el legislador.

Magister Artium - MA
Much has been researched in South Africa about the trauma of losing one’s home, one’s community and rebuilding one’s life in a new environment. Several books have been published tracking the lives of the forcibly removed and their responses to leaving District Six. My research focuses on a different group namely those who had been forcibly removed from the centre of Stellenbosch, called “Die Vlakte” during that time.Living and working with and among people who have experienced this removal, I was keen to research whether the impact of the trauma is currently manifesting in this specific community and if so, what the symptoms would be. This qualitative inquiry focuses on one particular individual, Mr. Hilton Biscombe. I selected him because he, who experienced the removal as a teenager, spent most of his later life determinedly collecting stories and documents relating to this incident. Mr.Biscombe is also the only person of whom I am aware who responded personally through compiling a book, making a DVD, writing poetry as well as an autobiography relating to this event. My inquiry into the ways trauma manifests in a narrative, will be based on two interviews: one conducted by a white man from the University of Stellenbosch thirty years after the event; and another interview, six years later, conducted by myself.Our understanding of trauma is usually associated with a death or injury or the possibility thereof, but it could also include the victim’s response to extreme fear, serious harm or threat to family members. According to van der Merwe and Vienings, people also become traumatized when witnessing harm, physical violence or death or the sudden loss or destruction of a victim’s home (van der Merwe & Vienings, 2001).So the issue of trauma is not in question, nor the fact that forced removals cause trauma. I am exploring testimony in the form of interviews for possible current manifestations of this trauma thirty-six years down the line.
South Africa

In this work we considered the influence of low alternating voltage of up to 100 V on the field photoemission process from a semiconductor tip under high voltage of 0.7-5.0 kV and photon excitation of 1.3 eV energy. Considered cathodes were made of high-resistivity silicon with p-type conductivity.

In grid-connected photovoltaic applications, a supply-frequency output transformer is normally used to isolate the inverter from the supply. This transformer is heavy, costly and adds to the overall power loss. However removal of the output transformer can result in unwanted DC components appearing in the inverter output current. Excessive DC current injection into the distribution network can affect distribution components as well as other loads connected to the network. There are various circuits which can be used to for grid connection without the use of an output transformer. These include the 2-level half-bridge and the H-bridge inverters. These circuits have the disadvantage of the requirement for higher rated power devices or increased EMI problems due to high frequency switching of the DC-link relative to earth. To overcome these problems, a three-level half-bridge inverter circuit is used, where the DC-link voltage can be twice the device voltage rating allowing the use low rated switching devices. The neutral conductor is connected to the mid-point of a split rail supply from PV array, and therefore the DC-link voltage is not switching relative to earth. The aim of this research is to minimise the DC current component in the output of a grid-connected inverter when a supply-frequency output transformer is not used. A three-level diode-clamped half-bridge inverter is proposed to interface the PV panel directly to the utility grid. The main contribution of this research lies in the development of an auto-calibration technique for the DC-link current sensors in the multi-level inverter. Combined with a current feedback control scheme this technique allows the minimisation of DC current offset drift in the Hall-Effect current sensors. Auto-calibrated DC-link current sensors in turn allow the inverter output current controller to minimise the output DC current component in spite of sensor drift and other disturbances. A comprehensive review on the different types of grid-connected PV systems, the problems caused by DC current injection into the grid, and up-to-date techniques to overcome this problem is included. The performance of the auto-calibration technique is investigated using both computer simulation and an experimental test rig.

The laminar structure of the neocortex is universal. In spite of some variation in structure and cell type, the composition of the 6 cortical laminae is conserved in virtually all neocortical areas and amongst all mammalian species. However, the function of cortical layers remains largely unknown. Here we seek to determine whether laminar-specific spontaneous current sources and sinks are distributed randomly, or whether they show repeating patterns. We further aim to investigate whether the time-course of current sources and sinks can be decomposed into separate independent components.To this end, we recorded Local Field Potentials (LFPs) from a linear array of equally spaced electrodes positioned locally perpendicular to the cortical manifold in rat somatosensory area S1Fl. The frequency-band specific Current Source Density (CSD) was derived from the filtered LFPs, which warded off the effects of volume conduction and resulted in reference independent signals. Principal Component Analysis (PCA) was applied to the CSD data in order to reduce dimensionality and noise, and to perform whitening. Temporal Independent Component Analysis (ICA) was then applied to each of the frequency-band specific CSD with reduced dimensions using the FastICA methods. The column vectors of the mixing matrix represent the spatial weights or 'strength of neural activation' across cortical layers, associated with each independent component. We tested the repeatability and reliability of the pattern of laminar activity across the cortex.The results show patterns of laminar-specific dipoles of current sources and sinks that are repeatable across sessions/subjects. Across most of the frequency bands, the maximum contribution towards the signal power is from layers 4, 5a and 5b. The cortical depth of dipoles depends on the frequency band. In the delta (1-4 Hz) band, a prominent dipole was observed in layer 6. In the theta (5-8 Hz) and alpha (9-14 Hz) bands, repeating dipoles overlap with layers 4, 5a and 5b. In the beta (15-30 Hz) band, a dipole was observed in layers 5a and 5b. In the low and high gamma bands (30-50 and 50-100 Hz, respectively), prominent dipoles overlapped with layer 3 and 4. Our findings suggest that spontaneous current sources and sinks emerge in a non-random, laminar and frequency-band specific manner, showing independent components that are consistent across runs and animals. We hypothesize that these independent components reflect separate contributions of thalamo-cortical input and of spontaneous activity of cortical origin.
La structure laminaire du neocortex est universelle. Au-delà de petites variations dans la structure et la composition cellulaire, l`organisation des 6 couches corticales est conservé à travers tout les mammifères. Pourtant, la fonction des différentes couches corticales est largement inconnue. Ici, nous examinons si les sources et puits de courent observés durant làctivité neuronale spontanée sont distribués de façon aléatoire dans les couches corticales ou si des motifs reproductibles peuvent être observé. Pour examiner cette question, nous avons enregistré des potentiels de champs locaux (LFP) avec une électrode linéaire positionnée perpendiculaire à la surface corticale de làire S1Fl du cortex somato-sensoriel du rat. Afin d`éliminer l`impact de la référence électrique commune, la densité de sources de courent (CSD) a été calculé à partir des LFP. De plus, le CSD a été filtré dans les bandes classiques de EEG. Ensuite, afin de réduire la dimensionnalité des données, lànalyse des composantes principales (PCA) a été appliqué. Finalement, les composantes temporelles indépendantes (tICA) ont été calculées pour chaque bande de fréquence en utilisant làlgorithme FastICA. La reproductibilité du motif laminaire fût testée pour chaque composante.Nos résultats suggèrent des motifs laminaires de dipôles de source de curent qui sont reproductible à travers les différentes sessions et sujets. Pour la majorité des bandes de fréquence, la contribution maximale à l`énergie du signal vient des couches 4, 5a et 5b. La profondeur des dipôles dépend de la bande de fréquence. Dans la bande delta (1-4 Hz), le dipôle majeur est situé dans la couche 6. Dans la bande theta (5-8 Hz) et alpha (9-14 Hz), les dipôles reproductibles sont situés dans les couches 4, 5a et 5b. Dans la bande beta (15-30 Hz) un dipôle a été observé dans les couches 5a et 5b. Finalement, dans la bande gamma (30- 50 et 50-100 Hz), le dipôle majeur est situé dans les couches 3 et 4.Nos résultats suggèrent que les sources et puits de curent observées durant làctivité neuronale spontanée présentes de motifs laminaires reproductibles et ne sont donc pas aléatoires. Nos supposons que ces composantes indépendantes reflètent des contributions séparées du thalamus et des autres régions corticales.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Neste trabalho desenvolve-se uma técnica para determinação da componente longitudinal do campo elétrico gerado por uma densidade superficial de corrente. A metodologia proposta baseia-se na diádica de Green da região em consideração, sendo estudadas regiões interiores em que existe uma solução analítica da equação de onda escalar em coordenadas ortogonais e regiões exteriores, em sistemas de coordenadas esféricas e cilíndricas. Para cada uma das soluções, mostra-se a convergência da expressão obtida para a componente longitudinal do campo elétrico, expressa por uma série ou integrais de funções modais. Baseado na metodologia desenvolvida, elabora-se um modelo de análise para determinação de campos e impedância característica em cabos coaxiais de seção arbitrária. O modelo é aplicado a cabos de seção circular e retangular. A metodologia de determinação de campos por diádicas de Green é ainda aplicada à análise de cabos coaxiais de seção retangular, com estais de fixação do condutor interno, localizados periodicamente.
It is developed a method for the determination of the longitudinal component of the electric field generated by a surface current density in the interior or the exterior regions. The proposed method is based on the dyadic Green´s function of the region under consideration, beeing analysed interior regions, assuming the knowledge of the analytical solution for the scalar wave equation in the orthogonal coordinate systems and external regions, using spherical and cylindrical coordinate systems. For the each solution, it is shown the convergence of the expression obtained for the longitudinal component of the electric field. Based on the developed method, a model of analysis is elaborated to determine the field and the characteristics impedance of coaxial cables of arbitrary cross section. The model is applied to cables with circular and rectangular sections. The dyadic Green´s function method is finally applied to the analysis of coaxial cables with internal metallic struts periodicaly placed.

The transport critical current density (J(_c)) of a 37 filament Bi-2223/Ag tape has been measured as a function of field and temperature from 4.2 K up to 90 K. Data have been obtained over a large current range from 10 mA up to 100 A and in fields up to 23 T with the tape in 3 orientations with respect to field. These comprehensive data have been used to test the predictions of the flux creep and weak link models used to explain J(_c) in Bi-2223 tapes. The J(_c)(B,T) dependence of optimised Bi-2223 tapes has been calculated using a curved film model. The model assumes perfect grain connectivity and that the local superconducting properties are equivalent to those in the best reported thin films. A comparison between the calculations and measured J(_c)(B,T) dependencies suggest that in high fields at 20 K, J(_c) in presently available industrially processed tapes is only a factor of 8 below the performance of ideal fully optimised tapes. Transport measurements have been made on Bi-2223 single filaments extracted from an alloy sheathed multifilamentary tape in liquid nitrogen at 77 K in fields up to 300 mT with the field aligned parallel and perpendicular to the a-b planes. Further Jc(B,T) data have been taken in a variable temperature insert at temperatures between 60 to 90 K in fields up to 15 T. In a study of the electric field-current density {E-J) characteristics of the c-axis orientated data at 77 K, negative curvature is observed in traces below 280 mT. However, the 280 mT trace exhibits both positive and negative curvature in different current regimes in contrast to the predictions of standard theory. A laboratory scale Bi-2223 superconducting magnet producing a maximum field of 1.29 T at 4.2 K has been designed and fabricated. The magnet comprises 6 resin impregnated double wound pancakes with a 40 mm bore fabricated via the react and wind route. Critical current density measurements have been made as a function of magnetic field, angle and strain at 4.2 K and 77 K on short samples of the constituent tape. The E-J characteristics of all component coils have been measured and a comparison with short sample data shows that minimal additional damage occurred beyond that produced by the bending strain on the tape and the long length variation in J(_c). Sufficient detail is provided for the non-specialist to assess the potential use of brittle superconducting tapes for magnet technology and construct a laboratory scale magnet.

This work deals with an origin of the harmonic currents, their classification into symmetrical components and their influence on neutral conductor in distribution systems. It analyses the heat strain increase in distribution cables and distortion of supply tension in consequence of harmonic zero component flows in distribution system and it provides possibilities of neutral conductor overload and break-in protection.

Three-phase voltage source converters(VSCs) have become the converter of choice in many ac medium and high power applications due to their many advantages, including low harmonics, high power factor, and high efficiency. Modular VSCs have also been a popular choice as building blocks to achieve even higher power, primarily through converter paralleling. In addition to high power ratings, paralleling converters can also provide system redundancy through the so-called (N+1) configuration for improved availability, as well as allow easy implementation of converter power management. Interleaving can further improve the benefit of paralleling VSCs by reducing system harmonic currents, which potentially can increase system power density. There are many challenges to implement interleaving in paralleled VSCs system due to the complicated relationships in a three-phase power converter system. In addition, to maximize the benefit of interleaving, current knowledge of symmetric interleaving is not enough. More insightful understanding of this PWM technology is necessary before implement interleaving in a real paralleled VSCs system. In this dissertation, a systematic methodology to analyze and design a paralleled three-phase voltage source converters with interleaving is developed. All the analysis and proposed control methods are investigated with the goal of maximizing the benefit of interleaving based on system requirement. The dissertation is divided into five sections. Firstly, a complete analysis studying the impact of interleaving on harmonic currents in ac and dc side passive components for paralleled VSCs is presented. The analysis performed considers the effects of modulation index, pulse-width-modulation (PWM) schemes, interleaving angle and displacement angle. Based on the analysis the method to optimize interleaving angle is proposed. Secondly, the control methods for the common mode (CM) circulating current of paralleled three-phase VSCs with discontinuous space-vector modulation (DPWM) and interleaving are proposed. With the control methods, DPWM and interleaving, which is a desirable combination, but not considered possible, can be implemented together. In addition, the total flux of integrated inter-phase inductor to limit circulating current can be minimized. Thirdly, a 15 kW three phase ac-dc rectifier is built with SiC devices. With the technologies presented in this dissertation, the specific power density can be pushed more than 2kW/lb. Fourthly, the converter system with low switching frequency is studied. Special issues such as beat phenomenon and system unbalance due to non-triplen carrier ratio is explained and solved by control methods. Other than that, an improved asymmetric space vector modulation is proposed, which can significantly reduce output current total harmonic distortion (THD) for single and interleaved VSCs system. Finally, the method to protect a system with paralleled VSCs under the occurrence of internal faults is studied. After the internal fault is detected and isolated, the paralleled VSCs system can continue work. So system reliability can be increased.
Ph. D.

Сістук, В. О. Підвищення показників маневреності кар'єрних самоскидів з електромеханічною трансмісією : авт. дис. к. т. н.: 05.22.12 / В. О. Сістук ; Дніпропетр. нац. ун-т залізн. трансп. ім. акад. В. Лазаряна. - Д., 2014. - 20 с. : іл., табл. ГРНТИ 52 УДК 622.271.33:629.3.072.4(043.3) Захист – 22 травня 2014 р.
UK: АНОТАЦІЯ Дисертацію присвячено підвищенню показників маневреності кар’єрних самоскидів з електромеханічною трансмісією. Вперше науково обґрунтовано можливість та доцільність застосування примусового управління обертанням задніх ведучих коліс кар’єрного самоскида з електромеханічною трансмісією, що дозволяє їм виконувати маневри із використанням силового довороту. Вперше розроблено математичну модель силового довороту, яка дозволяє визначити відношення кутових швидкостей задніх ведучих коліс окремо правого і лівого борту машини і її показники маневреності відповідно до коефіцієнта зчеплення на основі вперше встановлених аналітичних залежностей. Аналітична залежність відношення кутових швидкостей задніх ведучих коліс від коефіцієнта зчеплення доведена методом лабораторного експерименту на створеній лабораторній моделі, яка дозволяє моделювати процес виконання маневру колісною машиною при різних способах повороту. Створено алгоритм примусового управління обертанням задніх коліс кар’єрного самоскида, оснащеного електромеханічною трансмісією. Відповідно до розробленого алгоритму управління виготовлено електронний блок, який разом із додатковою датчиковою апаратурою, що встановлюється на кар’єрний самоскид БелАЗ-7513В, представляє собою систему примусового управління поворотом.
RU: АННОТАЦИЯ Диссертация посвящена вопросу улучшения маневренности карьерных самосвалов с электромеханической трансмиссией для повышения эффективности их работы в стесненном пространстве рабочих зон глубоких карьеров. В работе проведен комплекс теоретических, лабораторных, промышленных исследований маневренности карьерных самосвалов с электромеханической трансмиссией при выполнении маневров с применением силового доворота. Разработана математическая модель силового доворота колесной машины. Впервые установлена аналитическая зависимость отношения угловых скоростей задних ведущих колес отдельно правого и левого борта от коэффициента сцепления, которая позволяет разработать рациональный алгоритм принудительного управления вращением задних колес карьерного самосвала. Впервые установлены аналитические зависимости, позволяющие определить показатели маневренности колесной машины на основе требуемого отношения угловых скоростей задних ведущих колес. Математическое моделирование с использованием разработанной модели позволило установить, что для карьерного самосвала БелАЗ-7513 минимальный радиус поворота в сложных условиях эксплуатации (на увлажненном грунтовом покрытии основных трасс с коэффициентом сцепления φ=0,34) при выполнении маневра с использованием силового доворота может быть уменьшен с 13,0 до 10,1 м. Установленные математические зависимости проверены экспериментальным путем с применением лабораторной модели, созданной в соответствии с масштабным коэффициентом, равным 12,0, в качестве которого выступало отношение радиуса колеса карьерного самосвала к радиусу колеса модели. Лабораторная модель позволяет моделировать процесс выполнения маневра колесной машиной при различных способах поворота путем принудительного воздействия на частоты вращения электродвигателей задних колес. Разработан и реализован на карьерном самосвале БелАЗ-7513В в условиях ПАО «Центральный ГОК» алгоритм принудительного управления вращением задних колес карьерного самосвала с электромеханической трансмиссией. Отклонение между расчетным 100 % (1,12 м) минимальным радиусом поворота лабораторной модели и полученным в результате эксперимента составило 10,7 % (1,0 м), отклонение между расчетным 100% (10,38 м) минимальным радиусом поворота карьерного самосвала и полученным путем промышленных испытаний составило 7,9 % (11,30 м), что подтвердило соответствие аналитических и экспериментальных показателей. Использование системы принудительного управления поворотом на карьерных самосвалах с электромеханической трансмиссией позволяет повысить техническую производительность машин на 6,1 % путем уменьшения времени их маневрирования до 1,4 мин, установленного с помощью хронометража в промышленных условиях, а также позволяет снизить топливо-энергетические затраты на 2,3 %. Материалы диссертационных исследований приняты на предприятиях ПАО «Центральный ГОК», ПАО «АрселорМиттал Кривой Рог» и ООО «Кривбасс-БелАЗ-Сервис СП». Расчетный экономический эффект в условиях ПАО «АрселорМиттал Кривой Рог», полученный за счет повышения производительности карьерных самосвалов БелАЗ-7513 на 5,9%, для существующего парка из 8 машин составил 678,0 тыс. грн. / год. Таким образом, впервые научно обоснованы возможность и целесообразность применения принудительного управления вращением задних ведущих колес карьерного самосвала с электромеханической трансмиссией при маневрировании, что обеспечивает уменьшение радиуса поворота машины, повышая производительность промышленного автотранспорта карьеров.
EN: THE SUMMARY The thesis is dedicated to increasing of open pit trucks with electrical transmission indices of maneuverability. For the first time there has been scientifically grounded possibility and suitability of usage of forced controllability of rear leading wheels of open pit truck with electrical transmission that enables them to carry out maneuvers with the usage of a forced additional turn. For the first time there has been worked out mathematical model of a forced additional turn which enables to determine a correlation of angular velocity of rear leading wheels of starboard and port sides of a car and its indices of maneuverability relative to a friction coefficient on the basis of firstly determined analytical dependence. Analytical dependence of relation of rear leading wheels angular velocity to a friction coefficient has been proved with laboratory experiment method on a created laboratory model which enables to simulate the process of a wheel vehicle maneuver performing with various means of a turn. An algorithm of a forced controlling of rear wheels rotation of open pit truck with electrical transmission has been created. In accordance with the created algorithm an electrical block which coupled with additional sensor equipment that is installed on a pit truck BelAZ-7513B representing a forced turn controlling system has been manufactured.
Криворізький національний університет

U okviru doktorske disertacije, realizovane su podešljive feritne komponente sa jezgrima koja su proizvedena od komercijalno dostupnih ESL 40011 feritnih traka čije se induktivnosti podešavaju primenom jednosmerne struje. Rad realizovanih podešljivih feritnih komponenti je verifikovan u kolu DC-DC konvertora podizača napona. U disertaciji je predložena merna metoda koja omogućava ispitivanje uticaja jednosmerne struje na karakteristike SMD induktora postavljenih u realnom okruženju. Metoda je verifikovana na komercijalno dostupnim SMD induktorima.
As part of this thesis variable ferite components with cores produced from comercialy available ESL 40011 ferite tapes manufactured in Low Temperature Co-fired Ceramic technology are implemented. Inductivity of the components is varied by applying DC current. Functionality of the implemented ferite components is verified in a circuit of DC-DC boost converter. This thesis proposes a measurement method which enables examining the influence of DC current on the characteristics of SMD inductors in real environment. The method is verified on comercialy available SMD inductors

Ce travail s'inscrit dans une démarche générale de réduction des perturbations électromagnétiques émises par les équipements électriques. Il s'agit d'étudier les perturbations conduites générées par les convertisseurs statiques haute fréquence moyenne puissance dans l'optique de réaliser un outil d'aide a la conception prenant en compte ces phénomènes. Notre étude utilise comme support deux alimentations continu-continu isolées (alimentation flyback et alimentation forward) représentatives des problèmes rencontres. Après un bref rappel sur les normes et sur les équipements correspondants, un capteur de courant adapte a l'étude des perturbations électromagnétiques dans les convertisseurs statiques est présenté. Un des objectifs de l'étude est de pouvoir prédéterminer par simulation le niveau de perturbations d'un convertisseur. Pour cela, il est nécessaire de disposer d'un modèle électrique pour chacun des ensembles qui le constitue. Les modèles développés dans ce document concernent le transformateur et les composants a semi-conducteur (diode et igbt). Afin que ces modèles soient simples et facilement intégrables a un logiciel de simulation de type circuit, des modèles comportementaux issus de la littérature sont utilises. Notre travail consiste à adapter ces modèles à notre étude, c'est à dire à obtenir une bonne représentation des composants dans la bande de fréquence 10khz-30mhz. Le comportement des alimentations flyback et forward est alors analyse, essentiellement par simulation. A partir d'un schéma élémentaire (composants idéaux) de l'alimentation, les différents éléments parasites sont ajoutes étape par étape. L'analyse des modifications observées dans le domaine temporel et fréquentiel permet de cerner les diverses origines des perturbations. Cette démarche est reprise avec l'introduction d'un écrêteur puis d'un calc non dissipatif. Les résultats obtenus par simulation sont compares aux résultats expérimentaux afin de valider l'ensemble de l'étude (modèles et résultats d'analyse). Enfin, divers moyens de reduction des perturbations sont analyses. Tout d'abord deux moyens de reduction a la source sont proposes. Puis diverses solutions de reduction des couplages sont présentées. Finalement, le filtrage est abordé et les diverses cellules usuelles sont étudiées et comparées

In my graduation thesis I first of all shortly mentioned frequency–selection filters and their utilisations. However, the base point of this project was to acquaint with different types of signal flow diagrams with whom I should design and analyse frequency-selection filtres with conventional and also innovative active components. As the first I created signal flow diagrams for both voltage and current conveyors. These modern active components are well known today and enable the construction of circuits with better properties than circuits with traditional differentiating amplifiers with voltage feedback. Thereinafter I made signal flow diagrams for OTA component. Transconductancal amplifiers are well known active components used in various areas of analog signal processing. OTA amplifier is in fact the current source controlled by voltage difference, which is characterised by gm transconductance. Ulterior components were IOZ and IZN models of voltage amplifier with voltage gain A. The last component was COA amplifier. It is a current operational amplifier. COA model is fully dual component to VOA, which is classical voltage amplifier. In my project I used filters with two OTA components. This filter offers functions like low-pass filter, band-pass filter, high-pass filter, band-stop filter and two-phase network. Following this I used circuits with two GCC conveyors. These offer band-pass filter, low-pass filter, high-pass filter, band-stop filter and two-phase network. Ultimately I designed filters with COA components, which offer three transmission functions simultaneously (DP, PP and HP). Analysis of these filters was made with a help of PSpice computer programme.

Дисертація присвячена розробці науково-практичних засад удосконалення процесів регенерації гальванічних технологічних розчинів за допомогою методу мембранного електролізу. Проведено аналітичний огляд науково-технічної інформації щодо областей застосування та умов роботи мембранних електрохімічних пристроїв. На базі аналізу наукових джерел показано ефективність методу мембранного електролізу у процесах очищення водних розчинів від шкідливих та отруйних речовин. Показано, що підвищення якості та терміну роботи технологічних хромовмісних гальванічних ванн можливо завдяки роботі мембранних електрохімічних пристроїв. Для дослідження електровідновлення йонів металів, що присутні в хромовмісному розчині було застосовано метод вольтамперометрії з лінійним розгортанням потенціалу. Поляризаційними кривими встановлено залежності величини сили струму від рівня прикладеної напруги для катодного виділення кадмію та цинку при різних температурах. Поляризаційні криві демонструють зниження перенапруги в присутності йонів Zn2+, наявність йонів Cd2+ сприяє значній поляризації катоду, а підвищення температури зменшує поляризацію катоду. Підтверджено методом електронної мікроскопії з функціями рентгенофазового мікроанализу наявність у катодному осаді кадмію та цинку, йони яких знаходилися в якості домішок в аноліті. Поляризаційними кривими та методами електронної мікроскопії встановлено перенесення йонів через катіонообмінну мембрану між анодною та катодною камерами даного мембранного електрохімічного пристрою. Встановлено оптимальний діапазон значень рН катодної камери модуля електрохімічного для виділення металічних кадмію та цинку на катоді. У процесі статистичної обробки дослідних даних отримано рівняння регресій зміни середовища катодних камер електровідновлення кадмію та цинку в процесі масопереносу даних йонів металів через катіонообмінну мембрану RALEX®CMPES 11-66 електрохімічного модулю. Визначений експериментально та статистично підтверджений діапазон рН в межах 1,5-1,8 дозволяє отримувати у вигляді цінних продуктів металічні кадмій та цинк, які можливо використовувати в металургії на відміну від їх суміші гідроксидів у відстійниках гальванічного виробництва. У результаті проведених досліджень було розроблено лабораторну модель мембранного електрохімічного пристрою, експериментально досліджено закономірності масопереносу йонів Zn2+ та Cd2+ через катіонообмінну мембрану RALEX®CM-PES 11-66. Завдяки експериментальним дослідженням стало можливим створення нових промислових електрохімічних пристроїв, які здатні ефективно регенерувати вміст технологічних ванн. В процесі роботи вивчалися закономірності впливу наступних факторів на процес мембранного електролізу: концентрації забруднюючого йону металу, густини струму, температури та гідродинамічних умов примембранної зони аноліту. Експериментально встановлено умови результативної регенерації гальванічних розчинів. Визначено експериментально вплив концентрації забруднюючого йону металу в католіті при стабільних температурі та густині струму на катодний вихід металу. Експериментальні дослідження також було проведено при сталих концентраціях йонів забруднюючих металів в анолітах та змінних густинах струму або різних значеннях температури системи. Окрему увагу було спрямовано на застосування примусового механічного перемішування примембранної зони аноліту. Доведено збільшення масообміну через катіонообмінну мембрану RALEX®CM-PES 11-66 в процесі електролізу завдяки підвищенню концентрації забруднюючого йона в аноліті, підвищенні температури та підвищенні густини струму на мембрані. В результаті теоретичних та експериментальних узагальнень встановлено густину граничного струму для змодельованих розчинів пасивації кадмієвого та цинкового гальванічних покриттів. Встановлено підвищення, в результаті примусового механічного перемішування, виходу металу до 50%. Результати експериментальних досліджень були проаналізовані математично. Внаслідок удосконалення відомої математичної моделі було встановлено кінетичні параметри результатів досліджень зі зміною концентрацій забруднюючих йонів ванн пасивацій та зі зміною гідродинамічних умов та знайдено константи миттєвих швидкостей реакцій катодного електроосадження кадмію та цинку. Статистичний аналіз результатів досліджень описав адекватно закономірності мембранного електролізу рівняннями регресій. Побудовані рівняння прямих регресій експериментальних досліджень були перевірені регресійним та кореляційним аналізами. В процесі регресійного аналізу було уточнено коефіцієнти в рівняннях регресій. Кореляційний аналіз показав різні тісноти зв’язків в результаті знаходження коефіцієнтів кореляції Пірсона, що свідчить про наближення деяких експериментів як до лінійної кореляції так і навпаки. В результаті загальної математичної обробки даних результатів експериментів зі зміною концентрації, густини струму, температури та різних гідродинамічних умов були побудовані багатофакторні рівняння регресій мембранного катодного електроосадження кадмію та цинку. Для знаходження багатофакторних рівнянь регресій було застосовано програму Statgraphics Centurion 18-64X. Вперше отримані багатофакторні регресійні рівняння показують частку впливу кожного змінного фактору за допомогою відповідних коефіцієнтів. За побудованими моделями було з’ясовано вплив кожного змінного фактору на процеси електровідновлення кадмію та цинку. Таким чином побудовані математичні моделі дозволяють результативно проводити регенерацію пасивуючих розчинів завдяки регулювання впливу змінних факторів на процес. Статистичну значущість багатофакторних рівнянь регресій рівнянь було підтверджено критеріями Стьюдента, Фішера та Дарбіна-Уотсона. В результаті впровадження експериментальних та математичних досліджень в промислові умови створено промисловий електрохімічний пристрій, що дозволяє ефективно регенерувати склад технологічних ванн пасивацій кадмієвих та цинкових гальванічних покриттів. Встановлено конструктивні розміри та режимні параметри роботи промислового модуля електрохімічного. На реальних виробничих ваннах пасивацій практично підтверджено адекватність багатофакторних регресійних математичних моделей електровідновлення кадмію та цинку. В результаті промислового впровадження та роботи мембранних електрохімічних пристроїв крім ефективного очищення даних технологічних ванн від йонів Cd2+ та Zn2+ теоретично та експериментально доведено процес регенерації йонів хрому шестивалентного з йонів Cr3+ . На базі аналізу інформаційних джерел і застосування титрометричного та фотоколориметричного аналізів встановлено у промислових експериментальних умовах, в технологічних ваннах пасивацій кадмієвих та цинкових гальванічних покриттів, наявність процесу регенерації хромат-йонів на свинцевому аноді. Експериментальне дослідження процесу анодної регенерації підтвердило поступове зростання концентрації йонів хрому шестивалентного та поступове зниження концентрації йонів Cr3+ в ваннах пасивацій гальванічних покриттів. В результаті проведених досліджень встановлено ефективність регенерації хроматів на рівні 0,6-1,59 г/л на добу в працюючих ваннах пасивації об’ємом 150л. Практично встановлено зменшення рівня екологічної небезпеки ванн пасивацій в результаті тривалої роботи в них електрохімічних модулів за рахунок постійної регенерації хроматів. Даний процес призвів до зниження в них загальної концентрації хроматів. Доведено, що робота створених мембранних електрохімічних пристроїв знижує навантаження на очисні споруди гальванічної дільниці. Встановлене в процесі роботи модулів електрохімічних постійне утворення хроматів в пасивуючому розчині дало змогу створювати якісні конверсійні хроматні плівки на поверхні кадмієвого та цинкових гальванічних покриттів та економити натрій дихромат. Внаслідок утворення хроматів безпосередньо в пасивуючих ваннах зникла необхідність додавати часто натрій дихромат з ззовні. Встановлено зниження робочих концентрацій натрій дихромату в технологічних ваннах з 100 – 200 г/л до 30 – 50 г/л., завдяки його реагування з покриттям деталей та виносу в промивні ванни, що в результаті дало змогу знизити їх екологічну небезпеку в 3,75 рази. Вперше застосовано методику розрахунку еколого-економічної ефективності роботи даних електрохімічних пристроїв. Завдяки проведеним розрахункам показано результативність роботи створених промислових модулів електрохімічних в технологічних ваннах пасивації кадмієвих та цинкових гальванічних покриттів. Проведені експериментальні та статистичні дослідження, їх верифікація в промислових умовах реального гальванічного виробництва машинобудівної галузі, а також впровадження технологічних процесів електрохімічної регенерації хромовмісних технологічних гальванічних розчинів в АТ «Сумський завод «Насосенергомаш» (додатки Д, Е, Ж), дозволяють рекомендувати поширення використання даного методу мембранного електролізу для регенерації хромовмісних технологічних розчинів підприємств нашої країни.
The dissertation is devoted to the development of scientific and practical bases of improvement of regeneration processes in galvanic technological solutions by means of a membrane electrolysis method. An analytical review of scientific and technical information on the areas of application and operating conditions of membrane electrochemical devices were conducted. Based on the analysis of scientific sources, the effectiveness of the method of membrane electrolysis in the purification processes of aqueous solutions from harmful and toxic substances is shown. It is shown that the improvement of the quality and service life of technological chromium-containing galvanic baths is possible due to the operation of membrane electrochemical devices. The method of voltammetry with linear potential deployment was used as a study of the electrolitic reduction of metal ions present in the chromium-containing solution. Polarization curves the dependences of the magnitude of the current on the level of applied voltage for the cathodic release of cadmium and zinc at different temperatures. Polarization curves show a decrease in overvoltage in the presence of Zn2+ ions, the presence of Cd2+ ions contributes to a significant polarization of the cathode, and an increase in temperature reduces the polarization of the cathode. The presence of cadmium and zinc in the cathode deposit, the ions of which were present as impurities in the anolyte, was confirmed by electron microscopy with the functions of X-ray microanalysis. Polarization curves and electron microscopy methods established the transfer of ions through the cation exchange membrane between the anode and cathode chambers of this membrane electrochemical device. The optimal pH range of values electrochemical module cathode chamber for the release of metallic cadmium and zinc at the cathode has been established. In the result of statistical processing of experimental data, the regression equation of environment change of cathode chambers of electroreduction of cadmium and zinc in the mass transfer of data of metal ions through a cation exchange membrane RALEX®CM-PES 11-66 of the electrochemical module has received.The experimentally and statistically confirmed pH range in the range of 1.5-1.8 allows obtaining in the form of valuable products metallic cadmium and zinc, which can be used in metallurgy in contrast to their mixture of hydroxides in galvanic settlers. As a result, the conducted researches laboratory model of the membrane electrochemical device has developed, the regularities of mass transfer of Zn2+ and Cd2+ ions through the cation exchange membrane RALEX®CM-PES 11-66 had experimentally investigated.Thanks to experimental research, it has become possible to create new industrial electrochemical devices that can effectively regenerate the contents of technological baths. In the course of work, the regularities of influence of the following factors on the process of membrane electrolysis were studied: concentration of polluting metal ion, current density, temperature and hydrodynamic conditions of the near-membrane zone of the anolyte. The conditions for effective regeneration of galvanic solutions have been experimentally established. The effect of the concentration of the metal ion contaminant in the catholyte at a stable temperature and current density on the cathode yield of the metal was determined experimentally. Experimental studies were also performed at constant concentrations of pollutant metal ions in anolytes and variable current densities or different values of system temperature. Particular attention was paid to the use of forced mechanical stirring of the membrane zone of the anolyte. The increase of mass transfer through the cation exchange membrane RALEX®CM-PES 11-66 in the process of electrolysis due to the increase of the concentration of the contaminating ion in the anolyte, the increase of the temperature, and the increase of the current density on the membrane is proved. As a result of theoretical and experimental generalizations, the current limit density for simulated solutions of cadmium and zinc galvanic coatings passivations are determined. The increase of metal yield up to 50% as a result of forced mechanical mixing was established.The results of experimental studies have been analyzed mathematically. As a result of improving the known mathematical model, the kinetic parameters of research results with changes in the concentrations of contaminating ions of passivation baths and with changes in hydrodynamic conditions had established, instantaneous rate constants of cathodic electrodeposition of cadmium and zinc had found. Statistical analysis of research results is described adequately by the laws of membrane electrolysis by regression equations. The constructed equations of direct regressions of experimental researches had checked by regression and correlation analyzes. In the process of regression analysis, the coefficients in the regression equations were specified. Correlation analysis showed the different closeness of the relationships as a result of finding Pearson's correlation coefficients, which indicates the approximation of some experiments to both linear correlation and vice versa. As a result of general mathematical processing of the experiments results from data with changes in concentration, current density, temperature, and different hydrodynamic conditions, multifactor regression equations of membrane cathode electrodeposition of cadmium and zinc had constructed. Statgraphics Centurion 18-64X was used to find multifactor regression equations. The multifactor regression equations, obtained for the first time, show the share of influence of each variable factor by means of the corresponding coefficients. According to the constructed models, the influence of each variable factor on the electrical reduction processes of cadmium and zinc was determined. Thus constructed mathematical models allow to effectively carry out regeneration of passivating solutions by regulating the influence of variable factors on the process. The statistical significance of multifactorial regression equations was confirmed by the criteria of Student, Fisher, and Darbin-Watson. The industrial electrochemical device, allowing to regenerate effectively the structure of technological passivation baths of cadmium and zinc galvanic coatings, has been created in the result of introducing the experimental and mathematical researches in the industrial conditions. The structural dimensions and operating parameters of the industrial electrochemical module are established The adequacy of multifactor regression mathematical models of cadmium and zinc electroreduction has been practically confirmed on real passivation production baths. As a result of industrial implementation and operation of membrane electrochemical devices, in addition to effective purification of these process baths from Cd2+ and Zn2+ ions, the regeneration process of hexavalent chromium ions from Cr3+ ions has been theoretically and experimentally proved. Based on the analysis of information sources and the use of titrometric and photocolorimetric analyzes, the presence of chromate ion regeneration process at the lead anode was established in industrial experimental conditions, in technological baths of passivations of cadmium and zinc galvanic coatings. An experimental study of the anodic regeneration process confirmed the gradual increase in the concentration of hexavalent chromium ions and the gradual decrease in the concentration of Cr3+ ions in the passivation baths of galvanic coatings. As a result of the conducted researches, the efficiency of chromate regeneration was established at the level of 0.6-1.59 g / l per day in working passivation baths with a volume of 150 l. The reduction of the ecological danger level of passivation baths as a result of long-term operation of electrochemical modules in them due to constant regeneration of chromates had practically established. This process led to a decrease in the total concentration of chromates. It is proved that the operation of the created membrane electrochemical devices reduces the load on the treatment facilities of the galvanic section. The constant anodic regeneration of chromate anions installed during the operation of the electrochemical modules made it possible to create high-quality conversion chromate films on the surface of cadmium and zinc galvanic coatings and to save sodium dichromate. Due to the formation of chromates directly in the passivating baths, the need to often add sodium dichromate from the outside has disappeared. The reduction of working concentrations of sodium dichromate in technological baths from 100 - 200 g / l to 30 - 50 g / l had established due to its reaction with a coating of parts and removal to washing baths, which as a result allowed to reduce their ecological danger by 3.75 times. The calculation procedure on the ecological and economic efficiency of the electrochemical devices operation has been applied for the first time. Thanks to the calculations, the effectiveness of the created industrial modules of electrochemical in technological baths of passivation of cadmium and zinc galvanic coatings is shown. Experimental and statistical researches, their verification in industrial conditions of real factory galvanic production, and also the introduction of technological processes electrochemical regeneration of chromium-containing technological galvanic solutions in JSC Sumy plant "Nasosenergomash" (appendices Д, E, Ж), allow recommending to use this membrane electrolysis method for regeneration industrial chromiumcontaining technological solutions of our country.

State estimation plays an important role in modern power systems. The errors in the telemetered measurements and the connectivity information of the network will greatly contaminate the estimated system state. This dissertation provides solutions to suppress the influences of these errors. A two-stage state estimation algorithm has been utilized in topology error identification in the past decade. Chapter II discusses the implementation of this algorithm. A concise substation model is defined for this purpose. A friendly user interface that incorporates the two-stage algorithm into the conventional state estimator is developed. The performances of the two-stage state estimation algorithms rely on accurate determination of suspect substations. A comprehensive identification procedure is described in chapter III. In order to evaluate the proposed procedure, a topology error library is created. Several identification methods are comparatively tested using this library. A remote measurement calibration method is presented in chapter IV. The un-calibrated quantities can be related to the true values by the characteristic functions. The conventional state estimation algorithm is modified to include the parameters of these functions. Hence they can be estimated along with the system state variables and used to calibrate the measurements. The measurements taken at different time instants are utilized to minimize the influence of the random errors. A method for auto tuning of measurement weights in state estimation is described in chapter V. Two alternative ways to estimate the measurement random error variances are discussed. They are both tested on simulation data generated based on IEEE systems. Their performances are compared. A comprehensive solution, which contains an initialization process and a recursively updating process, is presented. Chapter VI investigates the errors introduced in the positive sequence state estimation due to the usual assumptions of having fully balanced bus loads/generations and continuously transposed transmission lines. Several tests are conducted using different assumptions regarding the availability of single and multi-phase measurements. It is demonstrated that incomplete metering of three-phase system quantities may lead to significant errors in the positive sequence state estimates for certain cases. A novel sequence domain three-phase state estimation algorithm is proposed to solve this problem.

Compte-tenu des progrès en matière de modélisation des dispositifs à courants de Foucault, et de résolution des problèmes inverses, on peut espérer pouvoir utiliser bientôt les outils de l'imagerie pour la reconstruction de défauts de pièce métalliques. Encore faut-il disposer d'un capteur approprie, qui échantillonne correctement le champ magnétique et qui soit modélisable. Dans cette thèse, nous présentons les pré déterminations nécessaires à la réalisation d'un capteur multiéléments, dans le cadre du contrôle à grande vitesse de tubes de générateurs de vapeurs. Cela conduit en la conception d'une sonde de type microsystème, avec détecteurs sur silicium et électronique de conditionnement embarquée. Par ailleurs, la reconstruction tomographique étant une opération coûteuse en temps de calcul, et elle ne doit être appliquée que sur des zones suspectes. Nous proposons un pré traitement rapide et efficace, base sur l'analyse en composantes principales pour détecter de telles zones, malgré un rapport signal à bruit souvent très mauvais. L'ensemble sonde/pré traitement donne des résultats très satisfaisant en termes de détection, et doit permettre par la suite une reconstruction tomographique des défauts.

Ce manuscrit de thèse propose l'optimisation de l'ensemble de la chaîne de reproduction sonore dans un système embarqué. Le premier axe de recherche introduit les notions générales concernant les systèmes audio embarqués nécessaires à la bonne compréhension du contexte de la recherche. Le principe de conversion de l'ensemble de la chaine est présenté afin de comprendre les différentes étapes qui composent un système audio. Un état de l'art présente les différents types de haut-parleurs ainsi que l'électronique associé les plus couramment utilisées dans les systèmes embarqués. Le second axe de recherche propose une approche globale : une modélisation électrique du haut-parleur (tenant compte d'un nombre optimal de paramètres) permet à un électronicien de mieux appréhender les phénomènes non-linéaires du haut-parleur qui dégradent majoritairement la qualité audio. Il en résulte un modèle viable qui permet d'évaluer la non-linéarité intrinsèque du haut-parleur et d'en connaitre sa cause. Les résultats des simulations montrent que le taux de distorsion harmonique intrinsèque au haut-parleur est supérieur à celui généré par un amplificateur. Le troisième axe de recherche met en avant l'impact du contrôle du transducteur. L'objectif étant de savoir s'il existe une différence, du point de vue de la qualité audio, entre la commande asservie par une tension ou par un courant, d'un micro-haut-parleur électrodynamique. Pour ce type de transducteur et à ce niveau de la modélisation, le contrôle en tension est équivalent à contrôler directement le haut-parleur en courant. Néanmoins, une solution alternative (ne dégradant pas davantage la qualité audio du signal) pourrait être de contrôler le micro-haut-parleur en courant. Le quatrième axe de recherche propose d'adapter les spécifications des amplificateurs audio aux performances des micro-haut-parleurs. Une étude globale (énergétique) démontre qu'un des facteurs clés pour améliorer l'efficacité énergétique du côté de l'amplificateur audio est la minimalisation de la consommation statique en courant, en maximalisant le rendement à puissance nominale. Pour les autres spécifications, l'approche globale se base sur l'étude de l'impact de la spécification d'un amplificateur sur la partie acoustique. Cela nous a par exemple permis de réduire la contrainte en bruit de 300%. Le dernier axe de recherche s'articule autour d'un nouveau type de transducteur : un micro-haut-parleur en technologie MEMS. La caractérisation électroacoustique présente l'amélioration en terme de qualité audio (moins de 0,016% de taux de distorsion harmonique) et de plage de fréquence utile allant de 200 Hz à 20 kHz le tout pour un niveau sonore moyen de 80dB (10cm). La combinaison de tous les efforts présente un réel saut technologique. Enfin, la démarche globale d'optimisation de la partie électrique a été appliquée aux performances du MEMS dans la dernière section, ce qui a notamment permis de réduire la contrainte en bruit de 500%.

La fabrication des composants semi-conducteurs à base de nitrure de gallium (GaN) connaît actuellement une grande expansion. Ce matériau, par ces propriétés physico-chimiques intéressantes, est un très bon candidat pour la fabrication des composants de puissance à haute fréquence de fonctionnement. Dans la pratique, avant d'intégrer ces composants dans un système électronique, l'analyse de leur fiabilité est une étape nécessaire pour valider la technologie de fabrication utilisée. L'objectif de ce travail est la détermination des mécanismes physiques responsables de la dégradation des performances des Transistors à Haute Mobilité Electronique (HEMT) à base d'hétérostructures AlGaN/GaN et AlInN/GaN. Dans un premier temps, la caractérisation en régime statique des composants, par des mesures de courant et de capacité à différentes températures, nous a permis de repérer certaines anomalies dans les caractéristiques des composants. Cette non-idéalité liée aux effets thermiques semble provenir des mécanismes de piégeage des porteurs par les défauts dans le matériau. Dans le but d'analyser ces mécanismes, des mesures de spectroscopie de défauts profonds (DLTS) ont été effectuées sur la capacité de type Schottky du contact de la grille. L'étape suivante a consisté à mesurer les pièges profonds dans les HEMTs par DLTS en courant de drain, de façon à déterminer quels défauts influencent directement le courant dans ces dispositifs. Cette étude a été effectuée sur différents composants avec différentes géométries pour analyser au mieux le comportement de ces pièges. L'étude du contact de grille est aussi une étape importante pour déterminer les origines de défaillance des composants. Pour cela, nous avons réalisé une étude approfondie sur les différents mécanismes de transport à travers la barrière métal/semi-conducteur. Cette étude nous a permis de conclure sur la stabilité du contact de grille après les tests de vieillissement accélérés.

S tím, jak se neustále vyvíjejí nové technologie pro energeticky náročná průmyslová odvětví, stávající zařízení postupně zaostávají v efektivitě a produktivitě. Tvrdá konkurence na trhu a legislativa v oblasti životního prostředí nutí tato tradiční zařízení k ukončení provozu a k odstavení. Zlepšování procesu a projekty modernizace jsou zásadní v udržování provozních výkonů těchto zařízení. Současné přístupy pro zlepšování procesů jsou hlavně: integrace procesů, optimalizace procesů a intenzifikace procesů. Obecně se v těchto oblastech využívá matematické optimalizace, zkušeností řešitele a provozní heuristiky. Tyto přístupy slouží jako základ pro zlepšování procesů. Avšak, jejich výkon lze dále zlepšit pomocí moderní výpočtové inteligence. Účelem této práce je tudíž aplikace pokročilých technik umělé inteligence a strojového učení za účelem zlepšování procesů v energeticky náročných průmyslových procesech. V této práci je využit přístup, který řeší tento problém simulací průmyslových systémů a přispívá následujícím: (i)Aplikace techniky strojového učení, která zahrnuje jednorázové učení a neuro-evoluci pro modelování a optimalizaci jednotlivých jednotek na základě dat. (ii) Aplikace redukce dimenze (např. Analýza hlavních komponent, autoendkodér) pro vícekriteriální optimalizaci procesu s více jednotkami. (iii) Návrh nového nástroje pro analýzu problematických částí systému za účelem jejich odstranění (bottleneck tree analysis – BOTA). Bylo také navrženo rozšíření nástroje, které umožňuje řešit vícerozměrné problémy pomocí přístupu založeného na datech. (iv) Prokázání účinnosti simulací Monte-Carlo, neuronové sítě a rozhodovacích stromů pro rozhodování při integraci nové technologie procesu do stávajících procesů. (v) Porovnání techniky HTM (Hierarchical Temporal Memory) a duální optimalizace s několika prediktivními nástroji pro podporu managementu provozu v reálném čase. (vi) Implementace umělé neuronové sítě v rámci rozhraní pro konvenční procesní graf (P-graf). (vii) Zdůraznění budoucnosti umělé inteligence a procesního inženýrství v biosystémech prostřednictvím komerčně založeného paradigmatu multi-omics.

Les plantes médicinales constituent une source inexhaustible de composés (des produits naturels - PN) utilisé en médecine pour la prévention et le traitement de diverses maladies. L'introduction de nouvelles technologies et méthodes dans le domaine de la chimie des produits naturels a permis le développement de méthodes ‘high throughput’ pour la détermination de la composition chimique des extraits de plantes, l'évaluation de leurs propriétés et l'exploration de leur potentiel en tant que candidats médicaments. Dernièrement, la métabolomique, une approche intégrée incorporant les avantages des technologies d'analyse moderne et la puissance de la bioinformatique s’est révélé un outil efficace dans la biologie des systèmes. En particulier, l'application de la métabolomique pour la découverte de nouveaux composés bioactifs constitue un domaine émergent dans la chimie des produits naturels. Dans ce contexte, le genre Acronychia de la famille des Rutaceae a été choisi sur la base de son usage en médecine traditionnelle pour ses propriétés antimicrobienne, antipyrétique, antispasmodique et anti-inflammatoire. Nombre de méthodes chromatographiques modernes, spectrométriques et spectroscopiques sont utilisées pour l'exploration de leur contenu en métabolites suivant trois axes principaux constituant les trois chapitres de cette thèse. En bref, le premier chapitre décrit l’étude phytochimique d’Acronychia pedunculata, l’identification des métabolites secondaires contenus dans cette espèce et l'évaluation de leurs propriétés biologiques. Le deuxième chapitre vise au développement de méthodes analytiques pour l'identification des dimères d’acétophénones (marqueurs chimiotaxonomiques du genre) et aux stratégies utilisées pour la déréplication de ces différents extraits et la caractérisation chimique des composés par UHPLC-HRMSn. Le troisième chapitre se concentre sur l'application de méthodologies métabolomique (RMN et LC-MS) pour l'analyse comparative (entre les différentes espèces, origines, organes), pour des études chimiotaxonomiques (entre les espèces) et pour la corrélation des composés contenus avec une activité pharmacologique
Medicinal plants constitute an unfailing source of compounds (natural products – NPs) utilised in medicine for the prevention and treatment of various deceases. The introduction of new technologies and methods in the field of natural products chemistry enabled the development of high throughput methodologies for the chemical composition determination of plant extracts, evaluation of their properties and the exploration of their potentials as drug candidates. Lately, metabolomics, an integrated approach incorporating the advantages of modern analytical technologies and the power of bioinformatics has been proven an efficient tool in systems biology. In particular, the application of metabolomics for the discovery of new bioactive compounds constitutes an emerging field in natural products chemistry. In this context, Acronychia genus of Rutaceae family was selected based on its well-known traditional use as antimicrobial, antipyretic, antispasmodic and anti-inflammatory therapeutic agent. Modern chromatographic, spectrometric and spectroscopic methods were utilised for the exploration of their metabolite content following three basic axes constituting the three chapters of this thesis. Briefly, the first chapter describes the phytochemical investigation of Acronychia pedunculata, the identification of secondary metabolites contained in this species and evaluation of their biological properties. The second chapter refers to the development of analytical methods for the identification of acetophenones (chemotaxonomic markers of the genus) and to the dereplication strategies for the chemical characterisation of extracts by UHPLC-HRMSn. The third chapter focuses on the application of metabolomic methodologies (LC-MS & NMR) for comparative analysis (between different species, origins, organs), chemotaxonomic studies (between species) and compound-activity correlations

博士
國立成功大學
電機工程研究所
79
The first purpose of this study is to investigate the efficacy of the different current patterns frequently used in electric current computed tomography (ECCT) for making the resistivity images. The second purpose is to characterize the relationship between surface voltage and current patterns. The third purpose is to present an experimentally adaptive method for the best current patterns. The last purpose is to propose the mathematical models for describing the phenomena of electrodes and compare with the experimental results. Based upon the above evaluations, the newly developed technique of ECCT is validated in depth. In this dissertation, the modalitiesand basic principles for the currently available computed tomography (CT) are briefly reviewed so as to compare with the ECCT. The historical development for the ECCT is also mentioned. Then, a system with 32 independent channels of current generators called Adaptive Current Tomography (ACT) for use in this study is described. Three current patterns are compared for their spatial resolution based upon two measures: maximum voltage difference and distinguishability. The current patterns studied are trigonometic current patterns, and a single current applied between an abjacent pair of electrodes and between an diametrically opposite pair of electrodes. The theoretical values of distinguishability and voltage difference for three current patterns are also found in excellent agreement with the experimental data. An experimentally adaptive scheme for obtaining the best current pattern is demonstrated. The eigencurrents of pseudo operator R, which characterizing the surface voltages and currents, are proved to be the trigonometric functions for the homogeneous and concentric inhomogeneous cases. Two methods using different currents are presented for obtaining their corresponding characteristic resistances. Comparing the signal-to-noise ratio as well as the image quality for the proposed currents, it is shown that the trigonometric currents are the best one among all the proposed currents. Finally, the mathematical models for electrode are described and proved with the experimental results. In summary, the trigonometic current patterns are better choice except the adaptive currents for electrical impedance imaging. An appropriate electrode models should be incorporated into the forward solver for improving the spatial resolution of images. Funture investigations in ECCT are also anticipated in the conclusion. 本研究之主要目的，第一是探討電流式電腦斷層掃描技術裡常用的各種電流之效用， 第二是建立體表電壓與電流圖型間的特徵關係，第三是提出適應實驗法以推得最佳電 流圖型，第四是建立一套完整的電極數學模型。 論文中首先扼要地回顧現有之傳統電腦斷層掃描技術的種類與基本原理；包括Ｘ光， 放射性，超音波和核磁共振；同時說明電流式電腦斷層掃描技術之進展與特性。本研 究所用的實驗設備為一具有32個電流產生器的適應電流式斷層掃描系統。 比較三種常用的電流圖型：空間三角凶暴電流圖型，對邊對電流圖型與相鄰對電流圖 型，實驗結果顯示，依最大壓差值來衡量，則可分辨的中心物直徑大小分別是9mm, 23mm，和79mm；以分辨值來判斷，則其直徑分別為9mm, 10mm ，和30mm。從適應實驗 法所得的結果，證明此法在推演中心物或離心物的最佳電流圖型皆可行與有效。對於 均質態與同心異質態，其擬運算子R 的特徵電流，理論推得為空間三角函數；至於特 徵電阻則可由直接測量法與傅氏分解計算而得，不過結果顯示前者較為準確。比較多 種電流圖型對雜訊的敏感度實驗數據，說明使用空間三角函數電流圖型，所測得的電 壓雜訊比最高。直接比較以兩種電流組所重建之電阻係數影像品質，更進一步說明三 角函數電流組在製作電阻抗影像為佳。最後，從理論推導而建立一完整電極數學模型 ，並由實驗加以證實。 總之，空間三角函數電流組，在製作電阻係數影像時，確實比其他電流組為優；但最 好是使用最佳電流組。再者，正向解法中當結合適當的完整電極數學模型，以提高影 像的解析度。最後，從本研究中，我們亦展望未來電流式電腦斷層技術之系統改良與 應用的方向。 論文共分十章，第一章回顧現有電腦斷層系統，第二章實驗系統說明，第三章提出拉 住演最佳電流圖型的實驗方法，第四章比較不同電流所產生的空間解析度，第五章建 立體表電壓與電流之特徵關係，第六章比較不同電流所產生之測量誤差，第七章比較 不同電流所重建之影像品質，第八章說明電極數學模型，第九章討論與結論，參考文 獻列於第十章，最後是兩則附錄，分別說明影像重建模擬程式與電極上電壓與電流分 佈之初步數學推導。

碩士
國立東華大學
電機工程學系
96
The subject of this thesis is to design Hall current transducers, which are the key components of electrical vehicle (EV). First, the power control unit (PCU) of hybrid electrical vehicle (HEV) is analyzed and the field-oriented controlled permanent magnet synchronous motor (PMSM) and permanent magnet synchronous generator (PMSG) of the HEV are described. In the EV, the currents of the PMSM, PMSG and battery charge and discharge system are required. Therefore, Hall current transducers are the key components of the EV. Then, the type, operating principle and circuit architecture of the closed-loop Hall current transducer, which is designed by Topstek INC., are introduced. Furthermore, the output characteristic of the Hall current transducer is adjusted by the laser trimming device. Finally, the specifications of the closed-loop Hall current transducer are verified by some experimental results using DC test device and response frequency test device.

碩士
國立交通大學
電信工程研究所
98
In this thesis, a new microwave component named current driver is proposed, which is capable of inducing ground edge current for radiation. Since the current driver serves as a small feeding structure with little contribution to radiation, it can be designed very small while good radiation properties are maintained. Compared to the miniaturized antennas, the approach that utilizes ground plane as the main radiation has smaller size and better antenna performance. Furthermore, a circuit model of the miniaturized balun (balanced to unbalanced transformer) is introduced to explain the current inducing mechanism and to provide some valuable physical insights into the properties of the current driver. The effect of a shielding metal box for the proximity circuitry near the current driver is also investigated. It is shown that the nearby shielding box has minor effect on the performance of the driver, which demonstrates the feasibility of the current driver for antenna applications in a compact wireless terminal. Given the benefits shown above, two antenna applications based on the current driver are presented. Both of them are fabricated on the low cost FR4 substrate of 0.4 mm. First, the current driver for WLAN 2.4 GHz designed with a lumped capacitor or printed capacitor has a small size of about 4 mm × 4 mm. The good radiation properties are obtained at 2.45 GHz with the measured radiation efficiency over 60 % and the nearly omni-directional radiation pattern with the average gain of about 0 dBi. Secondly, the dual-band current driver for WLAN 2.4/5/2 GHz applications is achieved by combining two single-band current drivers with the overall size of about 8.5 mm × 4 mm. The measured radiation performances at 2.4 GHz are similar to the ones for the previous single 2.4 GHz current driver, which has the measured antenna radiation efficiency higher than 60 % and nearly omin-directional patterns. At 5.2 GHz, the measured radiation efficiency is reduced to about 50 % due to the high dielectric loss caused by the FR4 substrate in the high frequency. The nearly omni-directional patterns are still maintained. The simulation and measurement results come to a great agreement. Based on the compactness and design flexibilities, the current driver is feasible for wireless applications

博士
國立成功大學
物理學系碩博士班
94
Abstract 　Magnetic reconnection usually takes place in a current sheet that separates two plasma regions having an antiparallel magnetic field component. Magnetic reconnection can lead to the formation of reconnection layers, where magnetic energy is conversed to plasma kinetic/thermal energy and magnetohydrodynamic (MHD) shocks and discontinuities are formed. In a hot plasma, such as in the solar corona or solar wind, the heat conduction effects should be considered because the conduction timescale is comparable to or shorter than the Alfvén timescale. In this thesis, the effects of heat conduction and magnetic guide field By in the magnetic reconnection layer is studied by solving one-dimensional Riemann problem for the evolution of an initial current sheet with an antiparallel component of magnetic fields on the two sides. In the numerical simulations, a dissipative MHD code with heat conduction and magnetic resistivity is used. 　First, the By effects on the current sheet evolution is considered in the resistive MHD. The initial magnetic fields across the initial current sheet is set to be B(z) = −Bxotanh(z/delta) +By +Bz , where Bx0 is the antiparallel component. In the symmetric case with By = 0, a pair of slow shocks are formed. For By ≠ 0 cases (even for a very small By), it is found that a pair of slow shocks and a pair of time-dependent intermediate shocks (TDISs) are formed. Notice that TDIS is not present in the By = 0 case. It is apparent that the case with By = 0 is a singular case. The plasma density and pressure increase and the magnetic field decreases across TDIS. It is further found that the rotation angle of tangential magnetic field across TDIS, Δphi, develops with time and gradually reaches its final value. It obeys Δphi(final) = 90°–phi∞, where phi∞ = tan-1(By/Bx) is half of the rotation angle of tangential magnetic field across the initial current sheet. Both pressure and temperature downstream of the slow shock decrease with phi∞, and increase with plasma beta∞. 　Second, the structure of slow shocks in the presence of a heat conduction parallel to the local magnetic field is studied. It is found that the slow shock consists of two parts: the isothermal main shock and foreshock. Significant jumps in plasma density, velocity and magnetic field occur across the main shock, but the temperature is found to be continuous across the main shock. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. It is shown that the jumps in plasma density, pressure, velocity, and magnetic field across the main shock are determined by the set of modified isothermal Rankine-Hugoniot conditions. It is also found that a jump in the temperature gradient is present across the main shock in order to satisfy the energy conservation. 　Third, the structure of slow shocks and intermediate shocks in the presence of a parallel heat conduction for an initial current sheet with By≠0 is studied. As before, a pair of slow shocks and a pair of TDISs are formed, and each slow shock consists of two parts: the isothermal main shock and the foreshock. The foreshock is found to reach a steady state with a constant width in the slow shock frame. The TDIS initially can be embedded in the slow shock’s foreshock structure, and then moves out of the foreshock region. With an increasing By, the propagation speed of foreshock leading edge tends to decrease and the foreshock reaches its steady state at an earlier time. Both the pressure and temperature downstream of the main shock decrease with increasing By. The present results can be applied to the shock heating in the solar corona and solar wind.

Development of alternative cathodes that have high capacity and long cycle life at an affordable cost is critical for next generation rechargeable batteries to meet the ever-increasing requirements of global energy storage market. Lithium-sulfur batteries, employing sulfur cathodes, are increasingly being investigated due to their high theoretical capacity, low cost, and environmental friendliness. However, the practicality of lithium-sulfur technology is hindered by technical obstacles, such as short shelf and cycle life, arising from the shuttling of polysulfide intermediates between the cathode and the anode as well as the poor electronic conductivity of sulfur and the discharge product Li2S. This dissertation focuses on overcoming some of these problems. The sulfur cathode involves an electrochemical conversion reaction compared to the conventional insertion-reaction cathodes. Therefore, modifications in cell-component configurations/structures are needed to realize the full potential of lithium-sulfur cells. This dissertation explores various custom and functionalized cell components that can be adapted with pure sulfur cathodes, e.g., porous current collectors in Chapter 3, interlayers in Chapter 4, sandwiched electrodes in Chapter 5, and surface-coated separators in Chapter 6. Each chapter introduces the new concept and design, followed by necessary modifications and development. The porous current collectors embedded with pure sulfur cathodes are able to contain the active material in their porous space and ensure close contact between the insulating active material and the conductive matrix. Hence, a stable and reversible electrochemical-conversion reaction is facilitated. In addition, the use of highly porous substrates allows the resulting cell to accommodate high sulfur loading. The interlayers inserted between the pure sulfur cathode and the separator effectively intercept the diffusing polysulfides, suppress polysulfide migration, localize the active material within the cathode region, and boost cell cycle stability. The combination of porous current collectors and interlayers offers sandwiched electrode structure for the lithium/dissolved polysulfide cells. By way of integrating the advantages from the porous current collector and the interlayer, the sandwiched electrodes stabilize the dissolved polysulfide catholyte within the cathode region, resulting in a high discharge capacity, long-term cycle stability, and high sulfur loading. The novel surface-coated separators have a polysulfide trap or filter coated onto one side of a commercial polymeric separator. The functional coatings possess physical and/or chemical polysulfide-trapping capabilities to intercept, absorb, and trap the dissolved polysulfides during cell discharge. The functional coatings also have high electrical conductivity and porous channels to facilitate electron, lithium-ion, and electrolyte mobility for reactivating the trapped active material. As a result, effective reutilization of the trapped active material leads to improved long-term cycle stability. The investigation of the key electrochemical and engineering parameters of these novel cell components has allowed us to make progress on (i) understanding the materials chemistry of the applied functionalized cell components and (ii) the electrochemical performance of the resulting lithium-sulfur batteries.
text