Estudos recentes em materiais unidimensionais indicaram a necessidade de alterações na equação da dinâmica de captura de portadores por armadilhas. As experiências de Haarer e Möhwald em fenantreno PMDA mostraram que o tempo de captura das armadilhas decai linearmente com o campo elétrico, a partir de um campo crítico. Neste caso podemos admitir a substituição da fórmula clássica do tempo de captura pela razão entre a distância entre as armadilhas e a velocidade do portador sob ação do campo elétrico. A velocidade do portador devido ao campo é dada pelo produto da mobiliade do portador pelo campo elétrico. Assim, a equação de balanço de cargas nas armadilhas fica alterada pelo aparecimento explícito do campo elétrico, ocasionando mudanças no próprio processo de transporte. Neste trabalho, tentou-se encontrar o comportamento de materiais unidimensionais, na região de campo de ocorrência deste fenômeno e em suas proximidades, estudando-se a característica voltagem-corrente, bem como alguns processos transientes de tratamento analítico ameno. / Recent studies in one-dimensional systems show that the trapping equations must be changed. Haarer and Möhwald experiments on Phenanthrene PMDA showed that the trapping time decays linearly with the electric field, from a critical field on. Therefore we can assume that one should substitute the classical formula of the trapping time by the ratio between the intertrap distance and the drift velocity. The drift velocity is given by the product of the carrier mobility by the field. Thus the equation of carrier trapping becomes modified by the explicit dependence on the field that leads to changes in the transport itself. In this work we tried to find the response of a material in which such behavior is observed, by studying the current voltage characteristic, and also some transient processes amenable to analytical treatment.

Estudos recentes em materiais unidimensionais indicaram a necessidade de alterações na equação da dinâmica de captura de portadores por armadilhas. As experiências de Haarer e Möhwald em fenantreno PMDA mostraram que o tempo de captura das armadilhas decai linearmente com o campo elétrico, a partir de um campo crítico. Neste caso podemos admitir a substituição da fórmula clássica do tempo de captura pela razão entre a distância entre as armadilhas e a velocidade do portador sob ação do campo elétrico. A velocidade do portador devido ao campo é dada pelo produto da mobiliade do portador pelo campo elétrico. Assim, a equação de balanço de cargas nas armadilhas fica alterada pelo aparecimento explícito do campo elétrico, ocasionando mudanças no próprio processo de transporte. Neste trabalho, tentou-se encontrar o comportamento de materiais unidimensionais, na região de campo de ocorrência deste fenômeno e em suas proximidades, estudando-se a característica voltagem-corrente, bem como alguns processos transientes de tratamento analítico ameno. / Recent studies in one-dimensional systems show that the trapping equations must be changed. Haarer and Möhwald experiments on Phenanthrene PMDA showed that the trapping time decays linearly with the electric field, from a critical field on. Therefore we can assume that one should substitute the classical formula of the trapping time by the ratio between the intertrap distance and the drift velocity. The drift velocity is given by the product of the carrier mobility by the field. Thus the equation of carrier trapping becomes modified by the explicit dependence on the field that leads to changes in the transport itself. In this work we tried to find the response of a material in which such behavior is observed, by studying the current voltage characteristic, and also some transient processes amenable to analytical treatment.

Disertacijoje aprašyti šešiafazių asinchroninių variklių dinaminiai modeliai ir ištirti pereinamieji vyksmai. Disertaciją sudaro įvadas, trys pagrindiniai skyriai, išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašas. Įvadiniame skyriuje suformuluota tiriamoji problema, darbo aktualumas, tyrimų objektas, darbo tikslas ir uždaviniai, tyrimų metodika, darbo mokslinis naujumas, rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatytos autoriaus paskelbtos publikacijos disertacijos tema ir pateikiamas perskaitytų pranešimų konferencijose sąrašas bei aprašoma disertacijos sandara. Pirmame skyriuje aprašyti daugiafazių variklių privalumai lyginant juos su trifaziais ir nurodyti jų taikymo atvejai. Aprašyti šešiafazių asinchroninių variklių tipai. Pateiktas šešiafazio asinchroninio variklio matematinis modelis. Pristatyti šešiafazių asinchroninių elektros pavarų valdymo metodai. Suformuluotos skyriaus išvados ir disertacijos uždaviniai. Antrajame skyriuje pateikti šešiafazio asinchroninio variklio kompiuteriniai modeliai sukurti pagal variklio statoriaus, rotoriaus srovių ir srautų išraiškas. Aprašyti imitacinių modelių naudojimo atvejai greitojo prototipo sistemose. Skyriaus pabaigoje suformuluotos išvados. Trečiajame skyriuje pristatyti šešiafazių asinchroninių pavarų imitaciniai ir eksperimentiniai tyrimai. Sudarytos sutelktosios dvisluoksnės sutrumpinto žingsnio ir poliaus žingsnio šešiafazių apvijų schemos. Pateikti šešiafazio... [toliau žr. visą tekstą] / Dynamic models for investigation transient processes of six phase induction motors are presented in this dissertation. The thesis layout consists of introduction, three main chapters, conclusions, bibliography and list of publications. The introduction reveals the investigation problem, importance of the work and the object of research as well as describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of obtained results and defended statements. The author’s publications on the subject of the defended dissertation, offering the material of made presentations in conferences and the structure of the dissertation are presented at the end of introduction. The advantages of multiphase motors over conventional three phase are presented in the first chapter. The applications with multiphase motors are reviewed. The types of six phase induction motors are presented. The mathematical model of six phase induction motor are composed. The control methods of six phase induction motors are reviewed. At the end of the chapter, conclusions and tasks for the dissertation are formulated. The second chapter is dedicated for methodology to develop two types mathematical models of six phase induction motor. First of them is composed according to stator and rotor current expressions and second one according to stator and rotor flux expressions. Fast prototype systems with simulation models are reviewed. At the end of the chapter... [to full text]

Experimente mit neuartigen Messverfahren lieferten Daten über die Struktur von transienten Flüssig-keits-Gas-Strömungen für die Entwicklung und Validierung von mikroskopischen, d.h. geometrieunabhängigen Konstitutivbeziehungen zur Beschreibung des Impulsaustauschs zwischen Flüssig-phase und Gasblasen sowie zur Quantifizierung der Häufigkeit von Blasenkoaleszenz und -zerfall. Hierzu wurde eine vertikale Testsektion der Zweiphasentestschleife MTLoop in Rossendorf genutzt, wobei erstmals Gittersensoren mit einer Auflösung von 2-3 mm bei einer Messfrequenz von bis zu 10 kHz angewandt wurden. Dabei wurde die Evolution von Gasgehalts-, Geschwindigkeits- und Bla-sengrößenverteilungen entlang des Strömungsweges und bei schnellen Übergangsprozessen aufge-nommen und so die für die Modellbildung erforderlichen Daten bereitgestellt. Für den Test der Mo-dellbeziehungen wurde ein vereinfachtes Verfahren zur Lösung der Strömungsgleichungen entlang des Strömungswegs erstellt. Es basiert auf der Betrachtung einer größeren Anzahl von Blasengrö-ßenklassen. Die erhaltenen numerische Lösungen haben erstmals gezeigt, dass der bei Erhöhung der Gasvolumenstromdichte stattfindende Übergang von einer Blasenströmung mit Randmaximum zu einem Profil mit Zentrumsmaximum und anschließend zu einer Pfropfenströmung ausgehend von einem einheitlichen Satz physikalisch begründeter und geometrieunabhängiger Konstitutivgleichun-gen modelliert werden kann. Die Modellbeziehungen haben sich in einem abgegrenzten Gebiet der Volumenstromdichten als generalisierungsfähig erwiesen und sind für den Einbau in CFD-Modelle geeignet. Weiterhin wurden Arbeiten zur Kondensation durchgeführt, die direkten Bezug zu den Kon-densationsmodellen haben, die in Thermohydraulik-Codes enthalten sind. Die Untersuchung liefert darüber hinaus experimentelle Daten für die Modellvalidierung hinsichtlich des Verhaltens und des Einflusses nichtkondensierbarer Gase. Hierfür wurden spezielle Sonden für die Bestimmung der Konzentration und für die Lokalisierung von Pfropfen nichtkondensierbarer Gase entwickelt und bei transienten Kondensationsversuchen in einem leicht geneigten Wärmeübertragerrohr eingesetzt.

Darbo metu apžvelgiami metodai pereinamiesiems procesams vamzdyne realizuoti. Aprašyta vamzdyno tėkmės pereinamųjų procesų dinamika matematinės lygtys ir sudarytas baigtinių elementų modelis skaitiniam vamzdynų pereinamųjų procesų modeliavimui. Panaudojant atgalinį slėgio bangos modeliavimą esant idealizuotam slėgio bangos sklidimo modeliui, sudaromas slėgio impulso vietos nustatymo algoritmas ir įvertinamos atsirandančios paklaidos. Realizuota programine įranga patikrinamas sudarytų modelių ir algoritmo teisingumas, bei pateikiami pasiūlymai, atsiradusioms paklaidoms mažinti. / During this research, the methods to realize the transient processes in piping systems are overviewed, also finite element method and idealized wave propagation of pressure mathematical models are set up. Using the backward pressure wave modelling at idealized pressure wave propagation model, piping system rupture location algorithm and the assessment of estimated errors are set up. With released software, the developed models and correctness of the algorithm are verified, and suggestions to reduce the resulting errors are presented.

Orientador: Marisa Masumi Beppu / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-12T23:04:08Z (GMT). No. of bitstreams: 1 Tiba_RafaelMassao_M.pdf: 4156025 bytes, checksum: 6b7f2bf2c33d458475abf019c06c839f (MD5) Previous issue date: 2009 / Resumo: O objetivo do trabalho foi analisar a adequação de Gráficos de Controle (coloquialmente chamadas também de Cartas de Controle) para o controle da qualidade e do desempenho de processos químicos. Dentro deste tema, Cartas de Controle usualmente aplicadas na indústria foram testadas e analisadas para verificar o seu impacto e aplicabilidade com dados provenientes de processos transientes. Os resultados obtidos indicaram que a utilização inadvertida dessas ferramentas (inicialmente concebidas para a indústria mecânica) pode trazer impactos indesejáveis como ocorrência de alarmes falsos e atraso na detecção. Os dados provenientes de indústrias químicas, particularmente quando apresentam autocorrelação, devem ser analisados de maneira diferenciada. Voltado para essa necessidade, uma ferramenta inédita foi criada para o controle de qualidade quando há esse tipo de dados: a carta para coeficientes angulares, que utiliza as tendências lineares de pequenos trechos de dados para antecipar a detecção de causas especiais. Entre as vantagens dessa ferramenta estão facilidade de aplicação (a carta dispensa recursos computacionais específicos ou utilização de séries temporais), alto desempenho e robustez frente a ruídos nos dados. Os gráficos de controle apresentam a vantagem de dispensar o conhecimento prévio do processo, podendo tratá-lo como uma "caixa preta", abordagem muito conveniente para processos muito complexos, com grande número de etapas e variáveis, onde abordagem fenomenológica e fundamental através de modelos diferenciais matemáticos entre variáveis dependentes e independentes pode ser bastante laboriosa na prática do controle. Para verificar se um ajuste comum ao processo possa não ser suficiente para fazer o processo convergir novamente ao "set point" (e voltar à zona de controle), sugere-se o uso de uma ferramenta auxiliar, a Dinâmica de Sistemas. Ela seria usada na indicação da necessidade de intervenção especial em um processo. Com o seu método particular de criar modelos multivariados, a Dinâmica de Sistemas fornece uma maneira qualitativa e quantitativa de identificar as variáveis críticas para a qualidade do processo e para analisar seu comportamento dinâmico bem como as relações multivariadas existentes em uma planta química, consistindo em uma grande oportunidade para ser aplicada no nível operacional. Ela pode servir para mostrar se uma determinada intervenção especial faria o sistema se descontrolar ainda mais (fato comum de processos com excesso de controle, "over-controlled") ou se poderia servir para fazê-la convergir novamente a uma zona de controle / Abstract: The purpose of this study was to examine the suitability of using ordinary control charts such as Shewhart's and Averages chart to control the quality and performance of chemical processes. Within this theme, control charts commonly used in industry were tested and analyzed to determine its impact and applicability with data from transient processes. The obtained results indicate that the inadverted use of such tools (originally designed for mechanical engineering, which has discrete processes) can lead to undesirable effects such as the occurrence of false alarms and delay on special causes detection. Therefore, data originated at chemical industries, especially when autocorrelation is present, must be analyzed through special techniques. Towards this need, a new tool was created specially to this sort of data: The Slope Chart, which uses the linear trends of small subgroups of data to anticipate special causes detection. The main advantages of this tool are ease of application (this charts does not requires specific computer resources or time series modeling), higher performance and robustness against noise. Control Charts allow users to deal with the process as "Black Boxes", not requiring previous knowledge about the process for special cause detection. For a high complexity process, where there are a considerable number of steps and variables, this is an advantage provided that classic control would require phenomenological studies which might be laborious. Therefore, an auxiliary tool in the cases where an ordinary correction may not enough is proposed. Furthermore, it has been proposed the use of System Dynamics as an auxiliary tool to indicate whether or not it is necessary to act at the process. With its particular method of creating multivariate models, the System Dynamics serves the purpose of quality control, providing both qualitative and quantitative ways to see critical variables to the process quality and to analyze its dynamic behavior and the existing multivariate relations in chemical industries, consisting of a significant opportunity to be used at operational level. It can be useful to simulate whether a potential action would bring more variability to the process (which is usual in overcontrolled processes) or would be useful to correct the process / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Experimente mit neuartigen Messverfahren lieferten Daten über die Struktur von transienten Flüssig-keits-Gas-Strömungen für die Entwicklung und Validierung von mikroskopischen, d.h. geometrieunabhängigen Konstitutivbeziehungen zur Beschreibung des Impulsaustauschs zwischen Flüssig-phase und Gasblasen sowie zur Quantifizierung der Häufigkeit von Blasenkoaleszenz und -zerfall. Hierzu wurde eine vertikale Testsektion der Zweiphasentestschleife MTLoop in Rossendorf genutzt, wobei erstmals Gittersensoren mit einer Auflösung von 2-3 mm bei einer Messfrequenz von bis zu 10 kHz angewandt wurden. Dabei wurde die Evolution von Gasgehalts-, Geschwindigkeits- und Bla-sengrößenverteilungen entlang des Strömungsweges und bei schnellen Übergangsprozessen aufge-nommen und so die für die Modellbildung erforderlichen Daten bereitgestellt. Für den Test der Mo-dellbeziehungen wurde ein vereinfachtes Verfahren zur Lösung der Strömungsgleichungen entlang des Strömungswegs erstellt. Es basiert auf der Betrachtung einer größeren Anzahl von Blasengrö-ßenklassen. Die erhaltenen numerische Lösungen haben erstmals gezeigt, dass der bei Erhöhung der Gasvolumenstromdichte stattfindende Übergang von einer Blasenströmung mit Randmaximum zu einem Profil mit Zentrumsmaximum und anschließend zu einer Pfropfenströmung ausgehend von einem einheitlichen Satz physikalisch begründeter und geometrieunabhängiger Konstitutivgleichun-gen modelliert werden kann. Die Modellbeziehungen haben sich in einem abgegrenzten Gebiet der Volumenstromdichten als generalisierungsfähig erwiesen und sind für den Einbau in CFD-Modelle geeignet. Weiterhin wurden Arbeiten zur Kondensation durchgeführt, die direkten Bezug zu den Kon-densationsmodellen haben, die in Thermohydraulik-Codes enthalten sind. Die Untersuchung liefert darüber hinaus experimentelle Daten für die Modellvalidierung hinsichtlich des Verhaltens und des Einflusses nichtkondensierbarer Gase. Hierfür wurden spezielle Sonden für die Bestimmung der Konzentration und für die Lokalisierung von Pfropfen nichtkondensierbarer Gase entwickelt und bei transienten Kondensationsversuchen in einem leicht geneigten Wärmeübertragerrohr eingesetzt.

В работе изучается распределённая нелинейная математическая модель гликолитического осциллятора Хиггинса с диффузией. Исследуется влияние диффузии на процессы, протекающие в модели, способность модели к формированию пространственных структур и её чувствительность к случайному шуму. Изучаются явления мультистабильности, стохастического доминирования, подавления автоколебаний диффузией, индуцированных шумом переходов между аттракторами. Рассмотрен вариант модели с одной и двумя пространственными координатами. / This thesis studies a distributed nonlinear mathematical model of the Higgins glycolytic oscillator with diffusion. The influence of diffusion on the processes occurring in the model, the ability of the model to form spatial structures and its sensitivity to random noise are investigated. The phenomena of multistability, stochastic preference, suppression of self-oscillations by diffusion, noise-induced transitions between attractors are studied. A variant of the model with one and two spatial coordinates is considered.

Les moteurs thermoacoustiques sont des machines thermodynamiques cycliques, qui font usage d’un gradient de température dans un matériau poreux pour générer du travail acoustique. Les modèles historiques décrivant ces moteurssont basés sur la théorie linéaire de la thermoacoustique, qui faillit à qualifier leurs conditions de fonctionnement etde saturation car différents effets non linéaires dissipent une partie non négligeable de l’énergie acoustique produiteet perturbent la distribution de température dans le noyau et l’éloignent de la distribution pour laquelle le moteur aété optimisé.Les travaux présentent les résultats expérimentaux issus d’une approche globale pour limiter l’impact de ces effetsnon linéaires, en ajustant le champ acoustique par un rétro-contrôle acoustique dans le moteur afin d’exploiter au mieux la distribution de température présente dans la machine.Un modèle simplifié est établi afin de comprendre les phénomènes en jeu dans les comportements dynamiques complexes observés expérimentalement, tels que l’augmentation de l’efficacité de conversion thermoacoustique coupléeà une baisse de la différence de température dans le régénérateur, l’extinction de l’auto-oscillation, ou un comportementhystérétique des seuils d’instabilité. Ce modèle est basé sur une approche à constante localisée et une description discrète des transferts thermiques pour réduire l’ordre de complexité du problème.Une étude complémentaire est présentée sur la propagation non linéaire dans les moteurs thermoacoustiques, pouvantamener à la formation d’ondes de choc. Des outils de description de cette propagation sont adaptés au cas desauto-oscillations thermoacoustiques afin de mettre en évidence les paramètres déterminant dans l’amplification duphénomène de cascade harmonique dans des configurations académiques de moteurs thermoacoustiques. / Thermoacoustic engines are heat engines in which a fluid in a porous media submitted to temperature gradient undergoesa thermodynamic cycle performing acoustic work. The design and optimization of such engine usually makes use of the linear theory of thermoacoustics. Though it is sufficient to describe the onset conditions of the instability, this theory fails to predict accurately the operating conditions of engines. Indeed, nonlinear effects develop due to high acoustic levels, which tend to perturb the temperature distribution in the thermoacoustic core and take it away from the ideal distribution for which the engine as been optimized.The work presented in this manuscript is devoted to a technique of control of the acoustic field distribution in the engine, in order to optimize the thermoacoustic interaction though nonlinear effects distort the temperature distribution. An auxiliary acoustic source added to the engine, powered by a feedback loop allows to control the efficiency of thermoacoustic conversion. Experimental results are presented, showing complex behavior such as oscillation death or hysteretic behavior of thresholds.A low order model of the engine under the influence of the feedback loop is presented, giving an insight of the physical phenomena at stake in this control. It is based on a lumped element electro-acoustic analogy, coupled with a discretization of the heat transfer description.A complementary study of the nonlinear propagation is presented for simple configurations of thermoacoustic prime movers. The condition leading to shock-wave formation are sought thanks to a numerical model, adapted to selfsustainedoscillations from a previous model of weakly nonlinear guided propagation.

Рассмотрены две пространственные модели реакции–диффузии, найдены параметрические зоны диффузионной неустойчивости. Исследованы сценарии детерминированной и стохастической генерации паттернов. Показано, что обе модели мультистабильны с большим количеством сосуществующих аттракторов–паттернов. Под воздействием шума возможны переходы между стационарными неоднородными состояниями, а также генерация паттернов в зоне диффузионной устойчивости. / Two spatial reaction-diffusion models are considered, and parametric zones of diffusion instability are found. Scenarios of deterministic and stochastic pattern formation are investigated. It is shown that both models are multistable with a large number of coexisting attractor-patterns. Under the influence of noise, transitions between stationary inhomogeneous states are possible, as well as the generation of patterns in the zone of diffusion stability.