Dissertations / Theses on the topic 'Unbalanced mode'

One of the challenging issues with the Microgrid is that the bidirectional power flow providedby the distributed generator (DG) which modify the fault current level. Furthermore, theinverter based-renewable energy source (IB-RES) limits the total fault current contributionto the grid due to its thermal capability. Since Microgrid should be able to operate in gridconnectedand islanded mode, protection strategies are needed to solve this challenging issue.By only having IB-RES and battery storage system, the fault condition and normaloperation cannot be distinguished. Apart from fault clearing issue, there is a consideration tostudy the fault isolation in the Microgrid under the limited fault current provided by IB-RES.To have fault isolation capability, the intelligent electrical device (IED) is needed. The firststep is to find a method that can detect a fault under the fault level modification constraint.This thesis presents a zero and negative sequence current protection to detect a fault.However, to make it selective, this protection will be applied directionally. It is common thatthe distribution grid has unbalanced load operation, thus providing zero and negativesequence component in the grid. To apply the directional zero and negative sequence currentprotection, the unbalanced load flow is simulated to distinguish the fault and normaloperation under unbalanced load condition.Safety and regulation are discussed briefly in this thesis. It is important that each of theIB-RES has fault ride-through (FRT) capability that follows a regulation. However, thisregulation is expected to have a coordination with the proposed protection in the Microgridso the reliability, selectivity, and sensitivity can be achieved in grid-connected and islandedmode. This thesis shows the coordination between fuses, IED, and inverter FRT capability.After providing a protection strategy, the adaptability of the proposed protection isassessed regarding of Microgrid expansion. The result shows that by applying the schemeand following the grading margin requirement that is presented in this thesis, the Microgridexpansion will not disrupt the proposed protection coordination. Since it is known that thedistribution grid is expanding its load capacity and microgeneration in continuous basis, it isconvenient that the proposed protection in the IED is expected to be adaptable, means that ithas a fixed IED setting when the grid is expanded. The analysis is performed by electrical transient analysis program (ETAP) and MatlabSimulink. The short circuit analysis, sequence-of-operation, and unbalanced load flow aresimulated by ETAP, while the protection stability is simulated by Matlab Simulink.
Ett problem som finns med microgrid är att de distribuerade produktionsgeneratorerna harett dubbelriktat effektflöde som modifierar felströmmen. Dessutom, inverterbaseradeförnyelsebara energikällor (IB-RES) begränsar det totala felströmsbidraget på grund av desstermiska kapacitet. Eftersom microgrids ska vara operativ vid både anslutning till externt nätsamt önätsdrift behövs skyddsstrategier för att kunna hantera fel, speciellt vid önätsdrift.Om endast IB-RES och batterilager används kan feldrift och normal drift inte särskiljas.Bortsätt från felhantering är det viktigt att studera felbortkoppling för microgrid underbegränsad felström som fås av IB-RES. För att kunna åstadkomma felbortkoppling behöveren IED (från engelskans Intelligent Electronic Device). Det första steget är att finna en metodför att kunna detektera fel under fel nivå modifiering. Denna avhandling tittar på att användanoll- och minusföljds ström sekvensskydd för att detektera fel. För att göra skyddet selektivtkommer det att titta på riktningen av effektflödet. I distributionsnät är det vanligt att haobalanserade laster vilket medför noll- och negativa sekvenskomponenter i nätet. För atttillämpa riktningsskydd för noll och negativ sekvens ström simuleras ett obalanserateffektflöde för att särskilja på feldrift och normal drift vid obalanserad last.Säkerhet och förordningar diskuteras kortfattat i denna avhandling. Det är viktigt att varjeIB-RES har en feltålighet som följer vissa förordningar. Denna förordning förväntassamordna det föreslagna skyddet i micronåt så att pålitlighet, selektivitet och känslighet kanåstadkommas vid nätanslutning och önätsdrift. Denna avhandling visar samordningen mellansäkringar, IED och feltåligheten för växelomriktare.Anpassningsförmågan för det föreslagna skyddet bedöms med avseende på expansion avmicrogrid. Resultatet visar att en expansion av ett microgrid inte kommer att störa denföreslagna samordningen om skyddsmetoden och tidsfördröjningskravet som presenteras idenna avhandling följs. Eftersom det är känt att distributionsnätet kommer att fortsätta ökasin lastkapacitet och mikrogenerering, är det lämpligt att skyddet förväntas varaanpassningsbart vilket innebär att det har en fast IED inställning när nätet expanderas.Analysen genomförs med mjukvarorna electrical transient analysis program (ETAP) ochMatlab Simulink. Kortslutningsanalysen, arbetssekvensen och obalanserad lastflödesimuleras av ETAP, medan skyddsstabiliteten simuleras av Matlab Simulink.

Диссертация на соискание ученой степени доктора технических наук по специальности 05.09.03 - электротехнические комплексы и системы. - Национальный технический университет "Харьковский политехнический институт". - Харьков, 2015. Диссертационная работа посвящена решению важной научно-технической проблемы создания обобщенной теории мощности (ТМ), единого комплексного подхода к компенсации и учету неактивных составляющих полной мощности (ПМ) для обеспечения оптимального режима потребления электрической энергии (ЭЭ) в точке подключения неидеальной нагрузки к сети с несимметричным напряжением. На основе теоретических исследований, использующих метод ортогонального разложения векторов мгновенных значений 3-фазного тока и напряжения, получена обобщенная векторная математическая модель (ВММ), которая классифицирует электроэнергетические режимы (ЭР) в 3-фазной схеме электроснабжения с помощью векторной мгновенной мощности (ММ). Сформулированы и обоснованы предложения политики повышения качества поставки и потребления электроэнергии в 3-фазной сети, сочетающие установку поставщиком в каждой точке подключения потребителя счетчика, измеряющего каждую ЭКТ, заключение публичного договора, в котором предусмотрена оплата каждой ЭКТ по своему тарифу, установки потребителем КУ, применение компенсации неактивных составляющих ПМ на каждом уровне для уменьшения групповых потерь в сетях поставщика. Предложенная политика позволит учесть разную степень влияния ЭКТ на качество электроэнергии и обеспечит потребителю выбор выгодного для него способа потребления электроэнергии, стимулирует установку КУ, а поставщику обеспечит надежную методологию повышения качества электроэнергии в рамках несимметрии нагрузки и напряжения.
Thesis for a Doctor’s degree in Engineering Sciences by specialty 05.09.03 - Electrical Engineering Complexes and Systems. - National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2015. The dissertation is devoted an important scientific and technical issues to improve the power quality of supply and consumption (SC) in three-phase networks through further development of die power theory, development of methods and ways of compensation, proposals for the accounting and payment of the inactive components of the apparent power (AP). A generalized mathematical model (GMM) of electric power processes (EPP) in a 3-phase SC scheme was developed. The model of 3-wire circuit is provided by a special (О-balanced) mode of the model 4-wire circuit The developed GMM classifies the SC modes using the vectorial instantaneous power (IP) and summarizes the class of models used in the theory of IP. For sinusoidal mode with asymmetric voltage the refines vectorial mathematical model (VMV) 3-phasors (complex rms vectors) was created. The analytical expressions for the integral characteristics of the classified modes are founded and their relationship with standard IP and vectorial IP are established. With asymmetrical voltage and asymmetrical loading a sinusoidal mode can be both unbalanced and pulsed. Each mode is represented by its power equation and the equivalent orthogonal decomposition of the 3-phase current Both decompositions are used to create the optimal mode of SC with a constant IP at asymmetrical voltage. The proposed compensator provides the non-puised energy supply with the highest possible power factor and with the same average (active) power as the initial current. Based on the evaluation and calculation of the power equation components of a unbalanced mode was developed a methodology for calculating the loss of the measuring selection. A methodology and technique of analytical calculation of additional losses on the passport data of the connected electrical equipment was proposed. Formulated and proved offers on differential measurement and payment of the energy components of AP will stimulate consumer sets the compensator, and provide a reliable methodology for improving the quality of SC (within unbalance loading and voltage).

Les énergies renouvelables, l’énergie sous la forme électrique et son transport à l’aide de réseaux électriques intelligents représentent aujourd’hui des enjeux majeurs car ils ont de grands impacts environnementaux et sociétaux. Ainsi, la production, le transport et la gestion de l’énergie électrique, continuent toujours à susciter un intérêt croissant. Pour atteindre ces objectifs, plusieurs verrous technologiques doivent être levés. Au-delà des questions liées aux architectures des réseaux électriques, aux modèles, aux outils de dimensionnement, à la formalisation de caractéristiques et d’indicateurs, aux contraintes et aux critères, à la gestion et à la production décentralisée, la qualité de la puissance électrique est centrale pour la fiabilité de l’ensemble du système de distribution. Les perturbations affectent la qualité des signaux électriques et peuvent provoquer des conséquences graves sur les autres équipements connectés au réseau. Les travaux de cette thèse s’inscrivent dans ce contexte et de fait ils sont orientés vers le développement de modèles, d’indicateurs et de méthodes de traitement des signaux dédiés à la surveillance en temps-réel des performances des réseaux de distribution électrique.Cette thèse analyse la qualité de la puissance électrique, en prenant en compte plusieurs caractéristiques bien connues ainsi que leur pertinence. Les modèles des systèmes électriques et les méthodes de traitement du signal pour estimer leurs paramètres sont étudiés pour des applications en temps-réel de surveillance, de diagnostic et de contrôle sous diverses conditions. Parmi tous, la fréquence fondamentale est l’un des paramètres les plus importants pour caractériser un système de distribution électrique. En effet, sa valeur qui est censée être une constante, varie en permanence et reflète la dynamique de l’énergie électrique disponible. La fréquence peut également être affectée par certaines productions d’énergie renouvelable et peut être influencée par des mauvaises synchronisations de certains équipements. En outre, la puissance absorbée par les charges ou produite par des sources est généralement différente d’une phase à l’autre. Évidemment, la plupart des installations électriques existantes avec plusieurs phases, qu’elles soient résidentielles ou industrielles, travaillent dans des conditions déséquilibrées. Identifier les composantes symétriques de tension est dans ce cas un moyen pertinent pour quantifier le déséquilibre entre les phases d’un système électrique.De nouvelles représentations de type espace d’état et modélisant des systèmes électriques sont proposées pour estimer la fréquence fondamentale et pour identifier les composantes symétriques de tension des systèmes électriques triphasés et déséquilibrés. Le premier modèle d’espace d’état proposé considère la fréquence fondamentale comme connue ou obtenue par un autre estimateur. En contrepartie, il fournit les autres paramètres caractérisant le système électrique. Un second modèle d’état-espace est introduit. Il est original dans le sens où il ne nécessite aucune connaissance de la fréquence fondamentale. Une de ses variables d’état est directement reliée à la fréquence et permet donc de la déduire. En outre, ce nouvel espace d’état est parfaitement capable de représenter des systèmes électriques à trois phases équilibrés et non équilibrés. [...]
Renewable energy, electricity and smart grids are core subjects as they have great environmental and societal impacts. Thus, generating, transporting and managing electric energy, i.e., power, still continue to drive a growing interest. In order to properly achieve these goals, several locks must be removed. Beyond issues related to the distribution architecture, the formalization of models, sizing tools, features and indicators, constraints and criteria, decentralized generation and energy management, power quality is central for the whole grid’s reliability. Disturbances affect the power quality and can cause serious impact on other equipment connected to the grid. The work of this thesis is part of this context and focuses on the development of models, indicators, and signal processing methods for power quality monitoring in time-varying power distribution systems.This thesis analyzes the power quality including several well-known features and their relevance. Power system models and signal processing methods for estimating their parameters are investigated for the purpose of real-time monitoring, diagnostic and control tasks under various operating conditions. Among all, the fundamental frequency is one of the most important parameters of a power distribution system. Indeed, its value which is supposed to be a constant varies continuously and reflects the dynamic availability of electric power. The fundamental frequency can also be affected by renewable energy generation and by nasty synchronization of some devices. Moreover, the power absorbed by loads or produced by sources is generally different from one phase to the other one. Obviously, most of the existing residential and industrial electrical installations with several phases work under unbalanced conditions. Identifying the symmetrical components is therefore an efficient way to quantify the imbalance between the phases of a grid. New state-space representations of power systems are proposed for estimating the fundamental frequency and for identifying the voltage symmetrical components of unbalanced three-phase power systems. A first state-space representation is developed by supposing the fundamental frequency to be known or to be calculated by another estimator. In return, it provides other parameters and characteristics from the power system. Another original state-space model is introduced which does not require the fundamental frequency. Here, one state variable is a function of the frequency which can thus be deduced. Furthermore this new state-space model is perfectly are able to represent a three-phase power system in both balanced and unbalanced conditions. This not the case of lots of existing models. The advantage of the proposed state-space representation is that it gives directly access to physical parameters of the system, like the frequency and the amplitude and phase values of the voltage symmetrical components. Power systems parameters can thus be estimated in real-time by using the new state-space with an online estimation process like an Extended Kalman Filter (EKF). The digital implementation of the proposed methods presents small computational requirement, elegant recursive properties, and optimal estimations with Gaussian error statistics.The methods have been implemented and validated through various tests respecting real technical constraints and operating conditions. The methods can be integrated in active power filtering schemes or load-frequency control strategies to monitor power systems and to compensate for electrical disturbances

Gaussian graphical model has been a popular tool to investigate conditional dependency between random variables by estimating sparse precision matrices. The estimated precision matrices could be mapped into networks for visualization. For related but different classes, jointly estimating networks by taking advantage of common structure across classes can help us better estimate conditional dependencies among variables. Furthermore, there may exist multilevel structure among variables; some variables are considered as higher level variables and others are nested in these higher level variables, which are called lower level variables. In this dissertation, we made several contributions to the area of joint estimation of Gaussian graphical models across heterogeneous classes: the first is to propose a joint estimation method for estimating Gaussian graphical models across unbalanced multi-classes, whereas the second considers multilevel variable information during the joint estimation procedure and simultaneously estimates higher level network and lower level network. For the first project, we consider the problem of jointly estimating Gaussian graphical models across unbalanced multi-class. Most existing methods require equal or similar sample size among classes. However, many real applications do not have similar sample sizes. Hence, in this dissertation, we propose the joint adaptive graphical lasso, a weighted L1 penalized approach, for unbalanced multi-class problems. Our joint adaptive graphical lasso approach combines information across classes so that their common characteristics can be shared during the estimation process. We also introduce regularization into the adaptive term so that the unbalancedness of data is taken into account. Simulation studies show that our approach performs better than existing methods in terms of false positive rate, accuracy, Mathews correlation coefficient, and false discovery rate. We demonstrate the advantage of our approach using liver cancer data set. For the second one, we propose a method to jointly estimate the multilevel Gaussian graphical models across multiple classes. Currently, methods are still limited to investigate a single level conditional dependency structure when there exists the multilevel structure among variables. Due to the fact that higher level variables may work together to accomplish certain tasks, simultaneously exploring conditional dependency structures among higher level variables and among lower level variables are of our main interest. Given multilevel data from heterogeneous classes, our method assures that common structures in terms of the multilevel conditional dependency are shared during the estimation procedure, yet unique structures for each class are retained as well. Our proposed approach is achieved by first introducing a higher level variable factor within a class, and then common factors across classes. The performance of our approach is evaluated on several simulated networks. We also demonstrate the advantage of our approach using breast cancer patient data.
Ph. D.

Aero-engine assemblies are complex structures typically involving two or three nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The deployment of SFDs into such structures is highly cost-effective but requires careful calculation since they can be highly nonlinear in their performance, particularly if they are unsupported (i.e. without a retainer spring). The direct study of whole-engine models with nonlinear bearings has been severely limited by the fact that current nonlinear computational techniques are not well-suited for complex large-order systems. The main contributions of this thesis are: • A procedure for unbalance response computation, suitable for generic whole-engine models with nonlinear bearings, which significantly extends the capability of current finite element packages. This comprises two novel nonlinear computational techniques: an implicit time domain integator referred to as the Impulsive Receptance Method (IRM) that enables rapid computation in the time domain; a whole-engine Receptance Harmonic Balance Method (RHBM) for rapid calculation of the periodic response in the frequency domain. Both methods use modal data calculated from a one-off analysis of the linear part of the engine at zero speed.• First-ever analyses on real twin-spool and three-spool engines. These studies illustrate the practical use of these solvers, provide an insight into the nonlinear dynamics of whole-engines and correlate with a limited amount of industrial experimental data. Both IRM and RHBM are directly formulated in terms of the relative response at the terminals of the nonlinear bearings. This makes them practically immune to the number of modes that need to be included, which runs into several hundreds for a typical engine. The two solvers are extensively tested on two/three-shaft engine models (with 5-6 SFDs) provided by a leading engine manufacturer using an SFD model that is used in industry. The tests show the IRM to be many times faster than an established robust conventional implicit integrator while achieving a similar level of accuracy. It is also shown to be more reliable than another popular implicit algorithm. The RHBM enables, for the first time, the frequency domain computation of the nonlinear response of whole-engine models. Its use is illustrated for both Single-Frequency Unbalance (SFU) excitation (unbalance confined to only one shaft) and Multi-Frequency Unbalance (MFU) excitation (unbalance located on two or more shafts, rotating at different speeds). Excellent correlation is demonstrated between RHBM and IRM.The parametric studies compare and contrast the frequency spectra for SFU and MFU cases. They also reveal the varying degree of lift at the unsupported SFDs. The sensitivity of the response to end-sealing and bearing housing alignment is also illustrated. It is demonstrated that the use of suitably preloaded vertically oriented “bump-springs” at the SFDs of heavy rotors produces a significant improvement in journal lift. It is also shown that the consideration of a slight amount of distributed damping in the structure significantly affects the predicted casing vibration levels, bringing them closer to measured levels, while having little effect on the SFD orbits.

Five chapters of this dissertation concentrate on the characterization and cancellation of high frequency parasitic parameters in EMI filters. One chapter addresses the interaction between the power interconnects and the parasitic parameters in EMI filters. The last chapter addresses the characterization, evaluation and design of noise separators. Both theoretical and experimental analyses are applied to each topic. This dissertation tries to explore several important issues related to EMI filters and noise separators. The author wishes to find some helpful approaches to benefit the understanding and design of EMI filters. The contributions of the dissertation can be summarized below: 1) Identification of mutual couplings and their effects on EMI filter performance 2) Extraction of mutual couplings using scattering parameters 3) Cancellation of mutual couplings to improve EMI filter performance 4) Cancellation of equivalent series inductance to improve capacitor performance 5) Analysis of mode transformations due to the imperfectly balanced parameters in EMI filters 6) Analysis of interaction between power interconnects and EMI filters on filter high-frequency performance 7) Modeling and design of high-performance noise separator for EMI diagnosis 8) Identification of the effects of parasitics in boost PFC inductor on DM noise Although all topics are supported by both theory and experiments, there may still be some mistakes in the dissertation. The author welcomes any advice and comments. Please send them via email to shuowang@ieee.org. Thanks
Ph. D.

The simplified models of synchronous generators, widely used in stability studies of large electric power systems, are not completely suitable for the stability analysis and the design of controllers of distributed synchronous generators, generally connected to typically unbalanced branches. To more accurately analyze the systems with distributed generation, it is necessary to utilize synchronous generator models that consider frequency variation in their electrical equations. Furthermore, this model must represent possible unbalanced three-phase voltages at the generator terminals as well. Nonetheless, to provide reliable responses, the parameters of this more detailed model should be known. Thus, this work assesses the influence of the parameters on the responses of a detailed synchronous generator model, suitable to depict unbalanced operating conditions, and proposes an approach for the estimation of its most important parameters. In the proposed structure, we first employ Trajectory Sensitivity Functions to evaluate the dependency of the responses of this model with respect to its parameters and, from that, we rank them according to their importance. Subsequently, we apply an estimation process that utilizes the Unscented Kalman Filter with the aid of a genetic algorithm to estimate the main parameters of this synchronous generator model under unbalanced operating conditions. To obtain the results and, therefore, assess the proposed estimation approach, we make use of a system which comprises a synchronous generator connected to a three-phase unbalanced load. In addition to the unbalanced operation of the test system, we also consider noises due to the constant load switching, typical of distribution systems. The estimations performed for three operating conditions of the generator were very satisfactory, which demonstrates the efficiency of the proposed approach to obtain adequate models for the description of synchronous generator operation under unbalanced operating conditions.
Os modelos simplificados de geradores síncronos, amplamente utilizados em estudos de estabilidade de grandes sistemas elétricos de potência, não são completamente adequados para a análise de estabilidade e projetos de controladores dos geradores síncronos distribuídos, geralmente conectados a sistemas tipicamente desequilibrados. Para que os sistemas com geração distribuída possam ser analisados mais fidedignamente, é necessária a utilização de um modelo de gerador síncrono que considere a variação de frequência em suas equações elétricas. Além disso, esse modelo também deve ser capaz de representar possíveis tensões trifásicas desequilibradas nos terminais do gerador. Entretanto, para que esse modelo mais detalhado possa fornecer respostas coerentes com a realidade, deve-se conhecer seus parâmetros. Dessa forma, este trabalho avalia a influência dos parâmetros nas respostas de um modelo de gerador síncrono mais detalhado, adequado para representar operações desbalanceadas, e propõe uma abordagem para a estimação de seus parâmetros mais importantes. Nessa estrutura, inicialmente empregam-se as Funções de Sensibilidade de Trajetória para avaliar a dependência das respostas desse modelo em relação aos seus parâmetros e, a partir disso, ordená-los conforme sua importância. Em seguida, aplica-se um processo de estimação que utiliza o Filtro de Kalman Unscented com o auxílio de um algoritmo genético para estimar os principais parâmetros desse modelo de gerador síncrono em condições de desbalanço. Para a obtenção dos resultados e consequente avaliação da abordagem de estimação proposta, utiliza-se um sistema composto por um gerador síncrono conectado a uma carga trifásica desbalanceada. Além da operação desbalanceada desse sistema teste, também são considerados ruídos devidos ao constante chaveamento de cargas, típicos de sistemas de distribuição. As estimações realizadas para três condições de operação do gerador foram bem satisfatórias, indicando a eficiência da abordagem proposta na obtenção de modelos adequados para descrever a operação de geradores síncronos em condições de desbalanço.

La marche est définie par des séquences de gestes cycliques et répétées. Il a été déjà montré que la vitesse et la variabilité de ces séquences peuvent révéler des aptitudes ou des défaillances motrices. L’originalité de ce travail est alors d’analyser et de caractériser les foulées de sujets âgés à partir des signaux de pression issus de semelles instrumentées lors de la marche, au moyen d’outils de traitement du signal. Une étude préliminaire, sur les signaux de pression générés lors de la marche, nous a permis de mettre en évidence le caractère cyclo-stationnaire de ces signaux. Ces paramètres sont testées sur une population de 47 sujets. Tout d'abord, nous avons commencé par un prétraitement des signaux et nous avons montré dans la première de cette thèse que le filtrage peut éliminer une partie vitale du signal. C’est pourquoi un filtre adaptatif basé sur la décomposition en mode empirique a été conçu. Les points de retournement ont été filtrés ensuite en utilisant une technique temps-fréquence appelée «synochronosqueezing». Nous avons également montré que le contenu des signaux de force de marche est fortement affecté par des paramètres inquantifiables tels que les tâches cognitives qui les rendent difficiles à normaliser. C’est pourquoi les paramètres extraits de nos signaux sont tous dérivées par une comparaison inter-sujet. Par exemple, nous avons assimilé la différence dans la répartition de poids entre les pieds. Il est également recommandé dans ce travail de choisir le centre des capteurs plutôt que de compter sur la somme des forces issues du réseau de capteurs pour la classification. Ensuite, on a montré que l’hypothèse de la marche équilibrée et déséquilibrée peut améliorer les résultats de la classification. Le potentiel de cette hypothèse est montré à l'aide de la répartition du poids ainsi que le produit de l'âge × vitesse dans le premier classificateur et la corrélation dans le second classificateur. Une simulation de la série temporelle de VGRF basé sur une version modifiée du modèle de Markov non stationnaire, du premier ordre est ensuite dérivée. Ce modèle prédit les allures chez les sujets normaux et suffisamment pour les allures des sujets de Parkinson. On a trouvé que les trois modes: temps, fréquence et espace sont très utiles pour l’analyse des signaux de force, c’est pourquoi l’analyse de facteurs parallèles est introduite comme étant une méthode de tenseur qui peut être utilisée dans le futur
Walking is defined as sequences of repetitive cyclic gestures. It was already shown that the speed and the variability of these sequences can reveal abilities or motorskill failures. The originality of this work is to analyze and characterize the steps of elderly persons by using pressure signals. In a preliminary study, we showed that pressure signals are characterized by cyclostationarity. In this study, we intend to exploit the nonstationarity of the signals in a search for new indicators that can help in gait signal classification between normal and Parkinson subjects in the elderly population. These parameters are tested on a population of 47 subjects. First, we started with preprocessing the vertical ground reaction force (VGRF) signals and showed in this first part of the thesis that filtering can remove a vital part of the signal. That is why an adaptive filter based on empirical mode decomposition (EMD) was built. Turning points are filtered using synochronosqueezing of time-frequency representations of the signal. We also showed that the content of gait force signals is highly affected by unquantifiable parameter such as cognitive tasks which make them hard to be normalized. That is why features being extracted are derived from inter-subject comparison. For example we equated the difference in the load distribution between feet. It is also recommended in this work to choose the mid-sensor rather than relying on summation of forces from array of sensors for classification purposes. A hypothesis of balanced and unbalanced gait is verified to be potential in improving the classification accuracy. The power of this hypothesis is shown by using the load distribution and Age×Speed in the first classifier and the correlation in the second classifier. A time series simulation of VGRF based on a modified version of nonstationary- Markov model of first order is derived. This model successfully predict gaits in normal subjects and fairly did in Parkinson’s gait. We found out that the three modes: time, frequency and space are helpful in analyzing force signals that is why parallel factor analysis is introduced as a tensor method to be used in a future work

The organic materials used for stator winding insulation are subject to deterioration from thermal, electrical, and mechanical stresses. Stator winding insulation breakdown due to excessive thermal stress is one of the major causes of electric machine failures; therefore, prevention of such a failure is crucial for increasing machine reliability and minimizing financial loss due to motor failure. This work focuses on the development of an efficient and reliable stator winding temperature estimation scheme for small to medium size mains-fed induction machines. The motivation for the stator winding temperature estimation is to develop a sensorless temperature monitoring scheme and provide an accurate temperature estimate that is capable of responding to the changes in the motors cooling capability. A discussion on the two major types of temperature estimation techniques, thermal model-based and parameter-based temperature techniques, reveals that neither method can protect motors without sacrificing the estimation accuracy or motor performance. Based on the evaluation of the advantages and disadvantages of these two types of temperature estimation techniques, a new online stator winding temperature estimation scheme for small to medium size mains-fed induction machines is proposed in this work. The new stator winding temperature estimation scheme is based on a hybrid thermal model. By correlating the rotor temperature with the stator temperature, the hybrid thermal model unifies the thermal model-based and the parameter-based temperature estimation techniques. Experimental results validate the proposed scheme for stator winding temperature monitoring. The entire algorithm is fast, efficient and reliable, making it suitable for implementation in real time stator winding temperature monitoring.

1. Einführung in die Theorie dynamischer Analysen mit Creo Simulate 2. Modalanalysen (Standard und mit Vorspannung) 3. Dynamische Analysen einschließlich Klassifizierung der Analysen; einige einfache Beispiele für eigene Studien (eine Welle unter Unwuchtanregung und ein Ein-Massen-Schwinger) sowie etliche Beispiele größerer dynamischer Systemmodelle aus unterschiedlichsten Anwendungsbereichen 4. Feedback an den Softwareentwickler PTC (Verbesserungsvorschläge und Softwarefehler) 5. Referenzen
1. Introduction to dynamic analysis theory in Creo Simulate 2. Modal analysis (standard and with prestress) 3. Dynamic analysis, including analysis classification, some simple examples for own self-studies (shaft under unbalance excitation and a one-mass-oscillator) and several real-world examples of bigger dynamic systems 4. Feedback to the software developer PTC (enhancement requests and code issues) 5. References

Thesis (M.S.)--Florida State University, 2005.
Advisor: Dr. Philip Cunningham, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed June 7, 2005). Document formatted into pages; contains xiv, 118 pages. Includes bibliographical references.

碩士
國立交通大學
管理科學系所
101
In the experimental design, sample size plays an important role in experimental reliability and confidence level. Under the constraints of costs and available resources, how can we determine the optimal sample size required to estimate characteristics of the population? In this research, we want to measure the power of intraclass correlation coefficient for the unbalanced case in the random effects model.

The participation of irrigation districts (IDs) in surface water transfers from agriculture-to-municipal uses is studied by examining IDs’ economic and political behavior, comparing their performance with non-districts (non-IDs), and analyzing the role of economic and demographic heterogeneities in water transfers. Economic modeling, econometric, and analytical techniques are used to investigate these issues. An economic model is developed to investigate how the collective-type institutional structure of IDs in the presence of local interdependencies (between internal water delivery and external water transfers) and increasing returns to scale in the internal water delivery causes reduction in marginal benefit of water transfers and the optimal transfers. The model is also used to investigate how the involvement of the U.S. Bureau of Reclamation in IDs causes more water uses in agriculture availing less for external transfers. The conjunction of multiple uses and exclusion rights without ownership rights in IDs’ water and vote-maximizing political structure of IDs are found to create disincentive for water conservation and transfers. Water transfer responses of IDs and non-IDs are empirically investigated by using a Quasi Maximum Likelihood Estimation (QMLE) technique. Based on the analysis of 38 years of time series water transfer data, IDs are found to be less responsive in water transfers relative to non-IDs in terms of water right-weighted transfers. It is found that water scarcity, private housing permits, and nonfarm establishments are positively associated with water transfers. The marginal effect of water scarcity on water transfer is stronger for non-IDs than for IDs. Impacts of economic and demographic heterogeneities on water transfer behavior of IDs are investigated using unbalanced panel data econometric techniques. Water right holdings and population in nearby cities of IDs are found to be significantly correlated with water transfer behaviors of IDs. Larger IDs with higher water right holdings and higher population centers in nearby cities are found to be more responsive to water transfers. The findings complement previous studies that commend public attention for policy redesign including institutional changes to motivate IDs to increase their water transfer activity.

碩士
明志科技大學
電機工程系碩士班
103
echanical crank presses in operation, the quality of the internal mechanism of Newton's second law of motion due to the inertia force generated on the rack, resulting in an imbalance of the machine, causing vibration punch when punching machines are more likely to cause life shortening . The conventional way to solve the dynamic imbalance punch, often with the addition of the slider balancing mechanism as a four-bar linkage group. Study purpose of this paper is to analyze the vibration generated by high-speed precision punch in the course of, and improve the machine vibration in the course of such value to enhance the punch. High-speed precision punching of the first crank provides manufacturers inertia force is derived in order to understand the operation of the power division of the punch of the process, and then use the lever weight and center of mass and other parameters of the slider do inertia cases and compared. Finally, the inertia force is derived as boundary conditions of numerical analysis and calculation method. In this paper, using numerical analysis method to analyze the calculation method can be used to calculate the numerical analysis computer software simulation, analysis software, ANSYS Workbench and so on through the finite elements, the present study first to draw the entire physical infrastructure software for frame part, using finite element Analysis ANSYS Workbench software for analysis, and the use of the inertial forces derived derived inertial force and the lateral thrust as boundary conditions to analyze, but to observe and analyze the results and the improvement of structural analysis results after comparison, to identify the partial structure The improvement programs can be used as a reference for future design improvements when.

碩士
大葉大學
事業經營研究所
92
Facing the phenomenon that teacher job vacancies are difficult to recruited, and many senior teachers are waiting to retired. This study view unemployed problems of “vagabond teacher” as an education government management range, and the quality of teacher also is an important loop in the education system. Therefore, we focus on unbalanced problems between teacher supply and demand. We use whole system viewpoint study education system structure, and build teacher supply and demand system dynamics model to find out fluctuate sources in education system. In order to observe education develop process in education system model, we divide education system to three subsystems. First, the science subsystem, second, the education policy and third is economic subsystem. Through the reality simulation, we can find the changed patterns of three variables, they are vagabond teacher, teacher quality and teacher supply and demand. Finally, we use policy-test methods to find out the best policies and then improve the system behavior. To avoid single policy to obstruct whole system long term develop make system bring out “fixes that fail” behavior.

碩士
國立清華大學
電機工程學系
104
Under the isolated microgrid, the output voltage of the inverter is influenced by different load conditions; further, the unbalanced load and the nonlinear load affect the output voltage of the inverter significantly. In order to mitigate voltage unbalance rate and improve total harmonic distortion (THD) caused by the unbalanced loads under the existing converter structure, this thesis not only applies model predictive control on inner current control loop to improve the dynamic response, but also performs the repetitive control on the outer loop to improve THD. Besides, the discrete model for analyzing effect of the predictive controller and repetitive controller are constructed to prove the stability of the system. The proposed control strategy is performed by Simulink; moreover, the presented theory are also verified by different simulations such as unbalanced loads, nonlinear loads and switching loads.

In this dissertation, a new non-global regression model - the partial linear threshold regression model (PLTRM) - is proposed. Various issues related to the PLTRM are discussed. In the first main section of the dissertation (Chapter 2), we define what is meant by the term “non-global regression model”, and we provide a brief review of the current literature associated with such models. In particular, we focus on their advantages and disadvantages in terms of their statistical properties. Because there are some weaknesses in the existing non-global regression models, we propose the PLTRM. The PLTRM combines non-parametric modelling with the traditional threshold regression models (TRMs), and hence can be thought of as an extension of the later models. We verify the performance of the PLTRM through a series of Monte Carlo simulation experiments. These experiments use a simulated data set that exhibits partial linear and partial nonlinear characteristics, and the PLTRM out-performs several competing parametric and non-parametric models in terms of the Mean Squared Error (MSE) of the within-sample fit. In the second main section of this dissertation (Chapter 3), we propose a method of estimation for the PLTRM. This requires estimating the parameters of the parametric part of the model; estimating the threshold; and fitting the non-parametric component of the model. An “unbalanced penalized least squares” approach is used. This involves using restricted penalized regression spline and smoothing spline techniques for the non-parametric component of the model; the least squares method for the linear parametric part of the model; together with a search procedure to estimate the threshold value. This estimation procedure is discussed for three mutually exclusive situations, which are classified according to the way in which the two components of the PLTRM “join” at the threshold. Bootstrap sampling distributions of the estimators are provided using the parametric bootstrap technique. The various estimators appear to have good sampling properties in most of the situations that are considered. Inference issues such as hypothesis testing and confidence interval construction for the PLTRM are also investigated. In the third main section of the dissertation (Chapter 4), we illustrate the usefulness of the PLTRM, and the application of the proposed estimation methods, by modelling various real-world data sets. These examples demonstrate both the good statistical performance, and the great application potential, of the PLTRM.
Graduate

博士
國立雲林科技大學
工程科技研究所
104
To address the voltage unbalance issues of the single-phase powered three-phase induction motor and the three-phase self-excited induction generator supplying single-phase loads, a novel balancing scheme with PC-based control called the two-dimensional perturbation and observation method is proposed and implemented. In the first part, the balancing scheme is composed of two static Var compensators (SVCs) in Steinmetz connection, and is modeled and analyzed by the positive- and negative-sequence equivalent circuits of the three-phase induction motor. The steady-state analysis allows the proper values of the energy-storage elements that balance the motor to be found. Simulations using the EMTP have shown that the motor can be balanced from starting to full load by adjusting the SVCs' firing angles. In the second part, the induction motor is operated as a self-excited induction generator. Appropriate control of the SVC firing angles also allows the single-phase loaded generator to work in a balance condition. Finally, a practical 0.5 HP cage induction motor with SVCs is used in the motor mode and the generator mode to test the PC-based control interface. The testing results indicate that the experimental results are in very good agreement with the simulation results, which demonstrates that the proposed PC-based control interface is feasible and can have more future applications.

The concern for the impact of the Health Care costs in private and public spending has been increasing because of its effect on the country’s financial stability. Therefore, several drivers of Health Care Expenditure have been studied. However, one of its most relevant drivers is Baumol’s cost disease. Baumol (1967) defines the cost disease as the difference between the wage growth in the overall economy and productivity growth in the services sector, such as the health care sector. This excess in wages causes the unit costs in the health care sector to increase over time. In order to understand if there is enough margin for policymakers to establish effective policies to control for the rise in health care costs, this thesis studies the impact of Baumol’s cost disease in this sector in OECD countries. To do so, I define an instrument, the adjusted Baumol variable, to measure Baumol’s cost disease and apply it to a panel data set containing 18 OECD member countries from 1970 to 2016. The results found show that the adjusted Baumol variable is explaining from 20% to 80% of the increase in Health Care expenditure, depending on the definition of the Baumol sector. These results may imply that policymakers still have some margin to implement policies since the rise in Health Care expenditure is partially explained by Baumol’s cost disease.
O impacto do aumento dos custos na despesa pública e privada relativos ao Sector da Saúde tem sido motivo de preocupação, uma vez que estes afetam a estabilidade financeira do país. Assim, foram estudados vários fatores influenciadores dos gastos associados ao sector da Saúde. De acordo com os resultados obtidos, a doença de custos de Baumol foi um dos fatores com maior impacto no crescimento dos referidos custos. Baumol (1967) define a doença dos custos como sendo a diferença entre o crescimento dos salários na Economia e o crescimento da produtividade no sector dos serviços, como é o caso do sector da saúde. Portanto, esta diferença faz com que os custos unitários no sector de saúde aumentem ao longo do tempo. Esta tese estuda o impacto da doença dos custos de Baumol no sector da Saúde com o intuito de compreender se existe espaço suficiente para a introdução de políticas eficazes na contenção do aumento dos custos associados a este sector. Portanto, foi definido um instrumento – variável de Baumol ajustada – para medir a doença de custos de Baumol e, posteriormente, foi aplicada com um conjunto de dados em painel, contendo 18 países membros da OCDE de 1970 a 2016. Os resultados encontrados mostram que a referida variável explica entre 20% a 80% do aumento dos gastos com a saúde dependendo da definição do sector de Baumol. Conclui-se que existe margem para implementar políticas pois o aumento das de saúde não é totalmente explicado pela doença dos custos de Baumol.