Dissertations / Theses on the topic 'Equivalent Circuit Analysis'
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1
Choi, Pyung. "An equivalent circuit structure macromodel for analog phase locked loops." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/14875.
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2
Danielsson, Christer. "Analysis of Synchronous machine dynamics using a novel equivalent circuit model." Licentiate thesis, Stockholm : Skolan för elektro- och systemteknik, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10510.
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3
Yasar, Orten Pinar. "Numerical Analysis, Design And Two Port Equivalent Circuit Models For Split Ring Resonator Arrays." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611620/index.pdf.
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Split ring resonator (SRR) is a metamaterial structure which displays negative permeability values over a relatively small bandwidth around its magnetic resonance frequency. Unit SRR cells and arrays have been used in various novel applications including the design of miniaturized microwave devices and antennas. When the SRR arrays are combined with the arrays of conducting wires, left handed materials can be constructed with the unusual property of having negative valued effective refractive indices.
In this thesis, unit cells and arrays of single-ring multiple-split type SRR structures are numerically analyzed by using Ansoft&rsquos HFSS software that is based on the finite elements method (FEM). Some of these structures are constructed over low-loss dielectric substrates and their complex scattering parameters are measured to verify the numerical simulation results. The major purpose of this study has been to establish equivalent circuit models to estimate the behavior of SRR structures in a simple and computationally efficient manner. For this purpose, individual single ring SRR cells with multiple splits are modeled by appropriate two-port RLC resonant circuits paying special attention to conductor and dielectric loss effects. Results obtained from these models are compared with the results of HFSS simulations which use either PEC/PMC (perfect electric conductor/perfect magnetic conductor) type or perfectly matched layer (PML) type boundary conditions. Interactions between the elements of SRR arrays such as the mutual inductance and capacitance effects as well as additional dielectric losses are also modeled by proper two-port equivalent circuits to describe the overall array behavior and to compute the associated transmission spectrum by simple MATLAB codes. Results of numerical HFSS simulations, equivalent circuit model computations and measurements are shown to be in good agreement.
4
Shamsi, Mohammad Haris. "Analysis of an electric Equivalent Circuit Model of a Li-Ion battery to develop algorithms for battery states estimation." Thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-298427.
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Batteries have imparted momentum to the process of transition towards a green future. However, mass application of batteries is obstructed due to their explosive nature, a trait specific to Li-Ion batteries. To cater to an efficient battery utilization, an introduction of a battery management system would provide an ultimate solution. This thesis deals with different aspects crucial in designing a battery management system for high energy as well as high power applications. To build a battery management system capable of predicting battery behavior, it is necessary to analyze the dynamic processes happening inside the battery. Hence, a battery equivalent circuit model is proposed in this thesis as well as proper analysis is done in MATLAB to project a generic structure applicable to all Li-Ion chemistries. The model accounts for all dynamic characteristics of a battery including non-linear open circuit voltage, discharge current and capacity. Effect of temperature is also modeled using a cooling system. The model is validated with test current profiles. Less than 0.1% error between measured and simulated voltage profiles indicates the effectiveness of the proposed model to predict the runtime behavior of the battery. Furthermore, the model is implemented with the energy as well as the power battery pack. State of charge calculations are performed using the proposed model and the coulomb counting method and the results indicate only a 4% variance. Therefore, the proposed model can be applied to develop a real-time battery management system for accurate battery states estimation.
5
Iseri, Kadir. "Analysis Of Dual-polarized Aperture-coupled Microstrip Antennas With H-shaped Slots And Equivalent Circuit Modeling Of H-shaped Slots." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614527/index.pdf.
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This thesis includes the design, production and measurement of a wideband dualpolarized
X-band aperture-coupled microstrip patch antenna. The wideband and
dual-polarized operation is achieved through the use of H-shaped coupling slots.
Therefore, the equivalent circuit modeling of a microstrip line fed H-shaped slot is
also studied in this thesis. A step-by-step procedure is followed during the design
process of the dual-polarized aperture-coupled microstrip antenna. First, an
aperture-coupled microstrip antenna with a single rectangular slot, that exhibits a
wideband characteristic for single polarization, is designed. Then, the design
procedure is repeated for an antenna with H-shaped slot in order to satisfy the same
specifications with a shorter slot. Finally, dual-polarized aperture-coupled
microstrip antenna is designed. At this configuration, two H-shaped slots are used
and they are placed orthogonal to each other. During the design process, the effects
of antenna parameters on the input impedance characteristics of the antenna are
investigated. These parametric analyses are done in CST Microwave Studio®. The v designed dual-polarized wideband aperture-coupled microstrip antenna is manufactured. Simulation results and measurement results are compared. During the equivalent circuit modeling of an H-shaped slot fed by a microstrip line, an approach based on the reciprocity theorem is utilized. The method was originally proposed for rectangular shaped slots, in this thesis it is generalized for arbitrarily shaped slots. Software codes are developed in MATLAB to calculate the equivalent impedance of the slot.
6
KRISHNAN, RAJESH. "ANALYSIS OF HIGH-FREQUENCY CHARACTERISTICS OF PLANAR COLD CATHODES." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061215895.
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Hasan, Iftekhar Hasan. "Modeling and Analysis of High Torque Density Transverse Flux Machines for Direct-Drive Applications." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1515582377354583.
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8
Hashimoto, Kazuki. "Analysis and Design of Air-Core Transformer Based on Internal Magnetic Flux Density Distribution for High-Frequency Power Converter." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263662.
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9
Parrow, Jacob Matthew. "Equivalent Circuit Modeling and Signal Integrity Analysis of Magneto-Static Responsive Structures, and Their Applications in Changing The Effective Permittivity of Microstrip Transmission Lines." Thesis, North Dakota State University, 2016. https://hdl.handle.net/10365/28002.
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This work presents the equivalent circuit model, ringing and overshoot characteristics, as
well as the ability of a new magneto-static responsive structure (MRS) to achieve the recon gurabil-
ity of a variable e ective permittivity structure (VEPS). Through the use of a static magnetic eld
and micro-sized conductive magnetic particles, the MRS can be used to connect separate transmis-
sion lines (TL) that operate up to a radio frequency of 5 GHz. The simulated and measured results
show the MRS functions well compared to other switching methods. The VEPS's ability to achieve
e ective permittivity recon gurability is also demonstrated, showing that the VEPS functions as
the well-known mushroom structure when the MRSs are in the on state and as a regular TL when
the MRSs are in the o state. Finally, several brief studies of the MRS are performed, including the
activation methods, MRS geometry, di erent types of magnetic particles, and smaller embedded
MRSs within the VEPS.
10
Logan, Thomas George. "Harmonic analysis of the brushless doubly-fed machine including single-phase operation." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/252277.
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11
Sienkiewicz, Lukasz Krzysztof. "Concept, implementation and analysis of the piezoelectric resonant sensor / Actuator for measuring the aging process of human skin." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0047/document.
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L’objectif de cet projet est la conception, réalisation et caractérisation d’un actionneur / capteur piézoélectrique piézorésonant destiné à la mesure du vieillissement de la peau humaine. L’étude présentée est le fruit d’une collaboration entre le groupe de recherche de l'Electrodynamique du INP-ENSEEIHT (Toulouse), LAPLACE Laboratoire de Recherche et l'École Polytechnique de Gdask, Département Génie Electrique et Automatique. Un concept d’actionneur / capteur pour la caractérisation des propriétés mécaniques des tissus mous a été présenté. Un actionneur piézoélectrique résonant, appelé "unimorphe" a été choisi parmi les différentes structures piézoélectriques fondées sur le cahier des charges. L'innovation du projet réside dans l'intégration de la méthode d'indentation dynamique en utilisant un unimorphe comme dispositif d'indentation. Ceci permet l'utilisation d'un certain nombre de propriétés électromécaniques favorables des transducteurs piézo-électriques. Ce mémoire est divisé en 7 chapitres. Le chapitre 1 présente la thèse et ses objectifs. Le chapitre 2 présente le phénomène piézoélectrique et les applications piézoélectriques dans les domaines de la médecine et de la bio ingénierie. Le chapitre 3 décrit le cahier des charges pour le transducteur développé. Le choix du transducteur unimorphe est ainsi justifié. Le chapitre 4 présente une description analytique du transducteur unimorphe, y compris les calculs de déformations statiques, la description du circuit équivalent de Mason, et la description des conditions de contact entre la sonde d'indentation et les matériaux testés. Le chapitre 5 contient l'analyse numérique du transducteur unimorphe en utilisant le modèle virtuel MEF. Les résultats de simulations statiques et modales sont décrits par deux géométries considérées du transducteur. Le chapitre 6 décrit le processus de vérification expérimentale des modèles analytiques et numériques développés pour le transducteur unimorphe. Enfin, le dernier chapitre comprend des conclusions générales concernant les résultats de recherche obtenus, ainsi que les travaux futurs possibles. Afin de vérifier la thèse d'un cycle complet de recherche a été effectuée, qui a couvert: étude analytique, l'analyse numérique (simulations MEF), réalisation de prototype, et la vérification expérimentale des actionneurs / capteurs piézoélectriques considérésThe main goal of the dissertation was following: preparation of a new concept, implementation and analysis of the piezoelectric resonant sensor/actuator for measuring the aging process of human skin. The research work has been carried out in the framework of cooperation between the INP-ENSEEIHT-LAPLACE, Toulouse, France, and at the Gdansk University of Technology, Faculty of Electrical and Control Engineering, Research Group of Power Electronics and Electrical Machines, Gdask, Poland. A concept of transducer for the characterization of mechanical properties of soft tissues was presented. The piezoelectric resonant, bending transducer, referred to as “unimorph transducer” was chosen from different topologies of piezoelectric benders based on the fulfillment of the stated requirements. The innovation of the project lies in the integration of the dynamic indentation method by using a unimorph as an indentation device. This allows the use of a number of attractive electromechanical properties of piezoelectric transducers. The thesis is divided into seven chapters. Chapter 1 states the thesis and goals of the dissertation. Chapter 2 presents piezoelectric phenomenon and piezoelectric applications in the fields of medicine and bioengineering. Chapter 3 describes the requirements for the developed transducer. The choice of unimorph transducer is justified. Chapter 4 presents an analytical description of the unimorph transducer, including the calculations of static deformations, equivalent circuit description, and description of the contact conditions between the transducer and the tested materials. Chapter 5 contains the numerical analysis of the unimorph transducer using FEM virtual model. Results of static and modal simulations are described for two considered geometries of the transducer. Chapter 6 describes the experimental verification process of analytic and numerical models developed for unimorph transducer. The final chapter includes general conclusions concerning obtained research results and achievements, as well as possible future works. In order to verify the proposition of the thesis a full research cycle was carried out, that covered: analytical study, numerical analysis (FEM simulations), prototype realization, and experimental verification of the considered (developed) piezoelectric sensor/actuator structures
12
Patil, Nishad. "Design And Analysis Of MEMS Angular Rate Sensors." Thesis, Indian Institute of Science, 2006. https://etd.iisc.ac.in/handle/2005/291.
Full textAbstract:
Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied.
Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied.
Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design.
Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventor-ware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware
Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4◦/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25◦/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2◦/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher
capacitance change for a given rotation in comparison to conventional comb-finger design.
The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.
13
Tinelli, Pascal. "Etude et realisation d'un detecteur microdosimetrique destine a la radioprotection." Toulouse 3, 1986. http://www.theses.fr/1986TOU30154.
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Cette etude a ete consacree a la realisation d'un compteur proportionnel au tissu biologique. Ce detecteur sensible aux neutrons et aux gamma, est destine a mesurer l'equivalent de dose dans le cadre de la radioprotection. L'analyse microdosimetrique des impulsions permet de calculer la dose absorbee et le facteur de qualite, en faisant eventuellement la discrimination entre les deux types de particules
14
Dareini, Ali. "Prediction and analysis of model’s parameters of Li-ion battery cells." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11799.
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Lithium-ion batteries are complex systems and making a simulation model of them is always challenging. A method for producing an accurate model with high capabilities for predicting the behavior of the battery in a time and cost efficient way is desired in this field of work. The aim of this thesis has been to develop a method to be close to the desired method as much as possible, especially in two important aspects, time and cost. The method which is the goal of this thesis should fulfill the below five requirements: 1. Able to produce a generic battery model for different types of lithium-ion batteries 2. No or low cost for the development of the model 3. A time span around one week for obtaining the model 4. Able to predict the most aspects of the battery’s behavior like the voltage, SOC, temperature and, preferably, simulate the degradation effects, safety and thermal aspects 5. Accuracy with less than 15% error The start point of this thesis was the study of current methods for cell modeling. Based on their approach, they are divided into three categories, abstract, black box and white box methods. Each of these methods has its own advantages and disadvantages, but none of them are able to fulfill the above requirements. This thesis presents a method, called “gray box”, which is, partially, a mix of the black and white boxes’ concepts. The gray box method uses values for model’s parameters from different sources. Firstly, some chemical/physical measurements like in the case of the white box method, secondly, some of the physical tests/experiments used in the case of the black box method and thirdly, information provided by cell datasheets, books, papers, journals and scientific databases. As practical part of this thesis, a prismatic cell, EIG C20 with 20Ah capacity was selected as the sample cell and its electrochemical model was produced with the proposed method. Some of the model’s parameters are measured and some others are estimated. Also, the abilities of AutoLion, a specialized software for lithium-ion battery modeling were used to accelerate the modeling process. Finally, the physical tests were used as part of the references for calculating the accuracy of the produced model. The results show that the gray box method can produce a model with nearly no cost, in less than one week and with error around 30% for the HPPC tests and, less than this, for the OCV and voltage tests. The proposed method could, largely, fulfill the five mentioned requirements. These results were achieved even without using any physical tests/experimental data for tuning the parameters, which is expected to reduce the error considerably. These are promising results for the idea of the gray box which is in its nascent stages and needs time to develop and be useful for commercial purposes.
15
Patil, Nishad. "Design And Analysis Of MEMS Angular Rate Sensors." Thesis, Indian Institute of Science, 2006. http://etd.iisc.ac.in/handle/2005/439.
Full textAbstract:
Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied.
Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied. Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design.
Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventorware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware
Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4º/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25º/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2º/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher
Capacitance change for a given rotation in comparison to conventional comb-finger design.
The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.
16
Bártů, Jan. "Analýza mechanického namáhání při zkratu ve vzduchem izolovaném rozváděči vn." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-317035.
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This Master thesis is based on problems of force effects of the magnetic field of short-circuit current. Firstly, I analysed the force action of the three phase busbars during the three-pole short circuit. The analysis was performed in the Ansys Maxwell program and I verified the correctness of the analysis by numerical calculation. The second practical part was executed for ABB company. The main task was to analyse the force effects of the short-circuit current in the HV switchgear with focusing on the arms and contact system of the circuit breaker. The simulations of the following configurations were performed in more details: three configurations of the simplified VD4 circuit breaker, two types of VD4 circuit-breaker contact systems and a linear circuit breaker configuration model. The objective was to calculate the forces acting on the current path of the arms and contact system of the VD4 circuit breaker during the three-phase short-circuit and to simulate the effects of forces on these current parts. For modelling of individual assemblies, calculations and simulations I used: SolidWorks 2014, Ansys Maxwell 16.0 and Ansys Workbench 14.5 programs. With SolidWorks 2014 3D CAD software were modelled simplified assemblies of circuit breakers and contact systems. These systems were imported into the Ansys Maxwell software, where the force effects of the magnetic field of the short-circuit current were calculated. In Ansys Workbench programme was simulated the effect of forces on the current circuit breakers. Moreover, the final deformations of the materials (with respect to the mechanical properties of the structure) were plotted. The analysis of force effects of the magnetic field was performed for the specified static short - circuit current value.
17
Patil, Nishad. "Design And Analysis Of MEMS Angular Rate Sensors." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/291.
Full textAbstract:
Design and analysis of polysilicon and single crystal silicon gyroscopes have been carried out. Variations in suspension design have been explored. Designs that utilize in-plane and out-of-plane sensing are studied.
Damping plays an important role in determining the sense response. Reduction in damping directly affects sensor performance. The various damping mechanisms that are prevalent in gyroscopes are studied.
Perforations on the proof mass are observed to significantly reduce the damping in the device when operated in air. The effects of perforation geometry and density have been analyzed. The analysis results show that there is a two orders of magnitude reduction in damping of thick gyroscope structures with optimized perforation design.
Equivalent circuit lumped parameter models have been developed to analyze gyroscope performance. The simulation results of these models have been compared with results obtained from SABER, a MEMS specific system level design tool from Coventor-ware. The lumped parameter models are observed to produce faster simulation results with an accuracy comparable to that of Coventorware
Three gyroscopes specific to the PolyMUMPS fabrication process have been designed and their performance analyzed. Two of the designs sense motion out-of-plane and the other senses motion in-plane. Results of the simulation show that for a given damping, the gyro design with in-plane modes gives a resolution of 4◦/s. The out-of-plane gyroscopes have two variations in suspension. The hammock suspension resolves a rate of 25◦/s in a 200 Hz bandwidth while the design with folded beam suspension resolves a rate of 2◦/s in a 12 Hz bandwidth. A single crystal silicon in-plane gyroscope has been designed with vertical electrodes to sense Coriolis motion. This design gives an order of magnitude higher
capacitance change for a given rotation in comparison to conventional comb-finger design.
The effects of process induced residual stress on the characteristic frequencies of the polysilicon gyroscopes are also studied. The in-plane gyroscope is found to be robust to stress variations. Analysis results indicate that the tuning fork gyroscope with the hammock suspension is the most susceptible to compressive residual stress, with a significant drop in sensitivity at high stress values.
18
Susetyo, Budi. "Modélisation de l'impédance harmonique de charges agrégées." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0027.
Full textAbstract:
Les applications de l’électronique de puissance contribuent à la pollution harmonique des réseaux électriques. Pour estimer le niveau de distorsion de tension, les différents composants du réseau doivent être modélisés en régime harmonique, en particulier les charges consommatrices, industrielles, commerciales et domestiques. L’étude concerne la modélisation de l’impédance harmonique des charges qui peuvent être séparées en deux grandes catégories: les charges passives et les charges dites actives qui réalisent une conversion d’énergie électromécanique. Les modèles disponibles pour les charges élémentaires sont récapitules en termes de complexité et de précision. Puis une méthode d’agrégation est développée, permettant d'obtenir un circuit équivalent d'ordre minimal et de structure compatible avec celle du réseau. La méthode d'identification des paramètres de ce circuit est basée sur une représentation fréquentielle de l’impédance harmonique, afin d'obtenir une réponse qui coïncide avec celle du réseau réel. Ce modèle agrège est utilise pour étudier la sensibilité de l’impédance harmonique aux variations aléatoires des paramètres caractéristiques du réseau et des charges.
19
Wang, Qian. "Elastomer-based Cellular Micromechanical Stimulators for Mechanobiological Study." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397610258.
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Tessarolo, Alberto. "Modeling and analysis of multiphase machines for high power applications." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3421670.
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This doctoral thesis is dedicated to the modeling and analysis of high-power multiphase electric machines.
In the first part, the multiphase technology and variety in the field of high power electric drives and power generation is illustrated by means of some significant industrial realizations which highlight the main design issues and advantages that may lead to choose a high number of phases in large electric machinery.
Subsequently, the attention is focused on the so called split-phase configurations, characterized by stator windings split into *N* three-phase sections. The modeling of these machines is revisited from an analytical viewpoint and an equivalent circuit representation is proposed for them; in particular, it is shown and experimentally proved that, when the number of stator sections *N* exceeds two, a magnetic cross-coupling arises between d-axis and q-axis equivalent circuits.
A different modeling technique, called Vector-Space Decomposition (VSD), is then considered and extended to any kind of multiphase configuration, whether symmetrical or asymmetrical, through suitable geometrical transformations. A special effort is particularly spent on setting forth a general methodology which allows for space harmonics (related to the
non-idealities of air-gap shape and winding distribution) to be included in the machine model through VSD. The result achieved is that some geometry- or design-related machine information which usually require finite-element simulations to be caught, can be successfully incorporated in the VSD lumped-parameter model of the *n*-phase machine, to an extent that is larger
and larger as *n* grows. As an application example, it is shown how space harmonic effects in the operation of a six-phase and a nine-phase salient-pole multiphase machines can be reproduced by time-stepping finite-element analysis and by the proposed lumped-parameter methodology with the same level of accuracy but with a significant time and computational saving in the last mentioned case.
A part of the thesis is also dedicated to model parameter calculation.
Addressing the case of a general number and distribution of stator phases, algorithms are proposed to compute magnetizing parameters through the winding function theory and analytical computation methods are proposed for self and mutual leakage inductance parameters. The accuracy of the proposed
computation method is assessed by comparison with measurements or real machines.
The final part of the thesis is devoted to the study of two detailed
phenomena which characterize high-power multiphase machines when supplied by multiple inverters. In the instance of multiple current-source inverters, a model is proposed and validated to describe commutation transients including the mutual interaction effects between different winding sections. In the instance of multiple voltage-source inverters, the low-frequency current
circulation phenomenon is investigated analytically and experimentally showing how it arises due to the internal non-ideal machine structure.Questa tesi di dottorato tratta della modellizzazione ed analisi di machine multiphase di alta potenza. Nella prima parte, si illustra la tecnologia multifase e la varietà delle sue forme progettuali nel campo degli azionamenti elettrici e della generazione di energia elettrica. Nella descrizione, si fa riferimento ad alcune realizzazione industriali significative che mettono in luce le principali problematiche e vantaggi che possono indurre alla scelta di una configurazione multifase in macchie elettriche di grossa taglia. Successivamente, viene trattata una particolare configurazione multifase detta “split-phase”, propria di quelle macchine il cui avvolgimento statorico è suddiviso in *N *sezioni multifase. La modellizzazione di queste macchine è rivisitata da un punto di vista analitico e ne viene fornita una rappresentazione in termini di circuito equivalente; in particolare, si dimostra teoricamente e sperimentalmente che, quando il numero *N* di sezioni statoriche è maggiore di due, si verifica un accoppiamento magnetico tra i circuiti equivalenti di asse diretto e di asse in quadratura. Successivamente, si considera una diversa tecnica di modellizzazione, chiamata Vector-Space Decomposition (VSD), con l’intento di darne una formulazione estesa che si applica trattare ogni tipo di configurazione multifase, sia simmetrica che non, ricorrendo ad opportune trasformazioni geometriche. Particolare attenzione è dedicata alla formulazione di un metodo generale che consente l’inclusione, nel modello della macchina con tecnica VSD, delle armoniche spaziali dovute alla non-idealità della geometria del traferro e della distribuzione degli avvolgimenti. In risultato che ne consegue è la possibilità di incorporare nel modello a parametri concentrati della macchina *n*-fase, realizzato con metodo VSD, alcune informazioni, legate alla geometria e al progetto di dettaglio della macchina, le quali normalmente possono essere tenute in considerazione mediante approcci di simulazione agli elementi finiti. La quantità di informazioni includibile nel modello a parametri concentrati secondo la tecnica proposta si mostra essere tanto maggiore quanto più grande è il numero di fasi *n*. Come esempio di applicazione, si mostra come gli effetti legati alle armoniche spaziali nel funzionamento di una macchina a poli salienti a 6 fasi e a 9 fasi possano essere riprodotti, mediante analisi agli elementi finiti nel dominio del tempo e mediante il metodo a parametri concentrati proposto, con lo stesso livello di accuratezza ma con un significativo risparmio di tempo e di risorse computazionali in quest’ultimo caso. Una parte della tesi è altresì dedicata al calcolo parametrico dei modelli. Riferendosi al caso di numero e distribuzione generici delle fasi di statore, vengono proposti algoritmi di calcolo dei parametri di magnetizzazione basati sulla teoria basata sulle “winding functions” e metodi di calcolo analitici per i parametri di auto e mutua induttanza dispersa. L’accuratezza dei metodi di calcolo proposti è verificata per confronto con misure su macchine reali. La parte finale della tesi è dedicata allo studio di due fenomeni dettagliati che caratterizzando le macchine elettriche multifase alimentate da più invertitori. Con riferimento all’alimentazione da più invertitori a corrente impressa, viene proposto e validato un modello che descrive i transitori di commutazione tenendo conto degli effetti di mutua interazione tra diverse sezioni dell’avvolgimento. Nel caso di alimentazione da più invertitori a tensione impressa, viene indagato analiticamente e sperimentalmente il fenomeno di correnti armoniche di ricircolo tra le fasi a bassa frequenza, dimostrando come esso si verifichi a causa della struttura interna non-ideale della macchina.
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Amani, Julian Alexander [Verfasser], Hans Christian [Akademischer Betreuer] [Gutachter] Hofsäss, Michael [Gutachter] Seibt, and Ørjan G. [Gutachter] Martinsen. "A novel approach of immittance-spectra analysis and how it resolves a decade-old deviation of the Frenkel-Poole model : Utilising process-specific physical models to find the electrical equivalent circuit representing the underlying physics in immittance spectroscopy / Julian Alexander Amani ; Gutachter: Hans Christian Hofsäss, Michael Seibt, Ørjan G. Martinsen ; Betreuer: Hans Christian Hofsäss." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1126248576/34.
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Skalka, Miroslav. "Analýza vlivu mechanického momentu asynchronního stroje na sycení magnetického obvodu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-233534.
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e main goal of this thesis is mechanical torque analysis of induction machine based on magnetic circuit saturation, oversaturated areas classification and the possibility of oversaturated areas reduction of their influence on machine properties. Whole problem is solved by finite element method in ANSYS program. Work is divided into the description and creating of electromagnetic model, a method of the induction machine equivalent circuit parameters determination, the electromagnetic field calculation by finite element method, experimental measurement using LabVIEW program with measurement accessories (PCIe card National Instruments), data processing program in DIAdem, results analysis of calculations in terms of magnetic circuit saturation, the influence of magnetic circuit material based on electromagnetic field distribution and the magnetic flux density along the air gap including spectral analysis using MATLAB and the electromagnetic torque and its parasitic torque components calculation.
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Penny, Melissa. "Mathematical modelling of dye-sensitised solar cells." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16270/.
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This thesis presents a mathematical model of the nanoporous anode within a dyesensitised solar cell (DSC). The main purpose of this work is to investigate interfacial charge transfer and charge transport within the porous anode of the DSC under both illuminated and non-illuminated conditions. Within the porous anode we consider many of the charge transfer reactions associated with the electrolyte species, adsorbed dye molecules and semiconductor electrons at the semiconductor-dye- electrolyte interface. Each reaction at this interface is modelled explicitly via an electrochemical equation, resulting in an interfacial model that consists of a coupled system of non-linear algebraic equations. We develop a general model framework for charge transfer at the semiconductor-dye-electrolyte interface and simplify this framework to produce a model based on the available interfacial kinetic data. We account for the charge transport mechanisms within the porous semiconductor and the electrolyte filled pores that constitute the anode of the DSC, through a one- dimensional model developed under steady-state conditions. The governing transport equations account for the diffusion and migration of charge species within the porous anode. The transport model consists of a coupled system of non-linear differential equations, and is coupled to the interfacial model via reaction terms within the mass-flux balance equations. An equivalent circuit model is developed to account for those components of the DSC not explicitly included in the mathematical model of the anode. To obtain solutions for our DSC mathematical model we develop code in FORTRAN for the numerical simulation of the governing equations. We additionally employ regular perturbation analysis to obtain analytic approximations to the solutions of the interfacial charge transfer model. These approximations facilitate a reduction in computation time for the coupled mathematical model with no significant loss of accuracy. To obtain predictions of the current generated by the cell we source kinetic and transport parameter values from the literature and from experimental measurements associated with the DSC commissioned for this study. The model solutions we obtain with these values correspond very favourably with experimental data measured from standard DSC configurations consisting of titanium dioxide porous films with iodide/triiodide redox couples within the electrolyte. The mathematical model within this thesis enables thorough investigation of the interfacial reactions and charge transport within the DSC.We investigate the effects of modified cell configurations on the efficiency of the cell by varying associated parameter values in our model. We find, given our model and the DSC configuration investigated, that the efficiency of the DSC is improved with increasing electron diffusion, decreasing internal resistances and with decreasing dark current. We conclude that transport within the electrolyte, as described by the model, appears to have no limiting effect on the current predicted by the model until large positive voltages. Additionally, we observe that the ultrafast injection from the excited dye molecules limits the interfacial reactions that affect the DSC current.
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Lu, Bin. "Energy Usage Evaluation and Condition Monitoring for Electric Machines using Wireless Sensor Networks." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14152.
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Energy usage evaluation and condition monitoring for electric machines are important in industry for overall energy savings. Traditionally these functions are realized only for large motors in wired systems formed by communication cables and various types of sensors. The unique characteristics of the wireless sensor networks (WSN) make them the ideal wireless structure for low-cost energy management in industrial plants.
This work focuses on developing nonintrusive motor-efficiency-estimation methods, which are essential in the wireless motor-energy-management systems in a WSN architecture that is capable of improving overall energy savings in U.S. industry.
This work starts with an investigation of existing motor-efficiency-evaluation methods. Based on the findings, a general approach of developing nonintrusive efficiency-estimation methods is proposed, incorporating sensorless rotor-speed detection, stator-resistance estimation, and loss estimation techniques. Following this approach, two new methods are proposed for estimating the efficiencies of in-service induction motors, using air-gap torque estimation and a modified induction motor equivalent circuit, respectively. The experimental results show that both methods achieve accurate efficiency estimates within ¡À2-3% errors under normal load conditions, using only a few cycles of input voltages and currents. The analytical results obtained from error analysis agree well with the experimental results.
Using the proposed efficiency-estimation methods, a closed-loop motor-energy-management scheme for industrial plants with a WSN architecture is proposed. Besides the energy-usage-evaluation algorithms, this scheme also incorporates various sensorless current-based motor-condition-monitoring algorithms. A uniform data interface is defined to seamlessly integrate these energy-evaluation and condition-monitoring algorithms. Prototype wireless sensor devices are designed and implemented to satisfy the specific needs of motor energy management. A WSN test bed is implemented. The applicability of the proposed scheme is validated from the experimental results using multiple motors with different physical configurations under various load conditions. To demonstrate the validity of the measured and estimated motor efficiencies in the experiments presented in this work, an in-depth error analysis on motor efficiency measurement and estimation is conducted, using maximum error estimation, worst-case error estimation, and realistic error estimation techniques. The conclusions, contributions, and recommendations are summarized at the end.
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Penny, Melissa. "Mathematical modelling of dye-sensitised solar cells." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16270/1/Melissa_Penny_Thesis.pdf.
Full textAbstract:
This thesis presents a mathematical model of the nanoporous anode within a dyesensitised solar cell (DSC). The main purpose of this work is to investigate interfacial charge transfer and charge transport within the porous anode of the DSC under both illuminated and non-illuminated conditions. Within the porous anode we consider many of the charge transfer reactions associated with the electrolyte species, adsorbed dye molecules and semiconductor electrons at the semiconductor-dye- electrolyte interface. Each reaction at this interface is modelled explicitly via an electrochemical equation, resulting in an interfacial model that consists of a coupled system of non-linear algebraic equations. We develop a general model framework for charge transfer at the semiconductor-dye-electrolyte interface and simplify this framework to produce a model based on the available interfacial kinetic data. We account for the charge transport mechanisms within the porous semiconductor and the electrolyte filled pores that constitute the anode of the DSC, through a one- dimensional model developed under steady-state conditions. The governing transport equations account for the diffusion and migration of charge species within the porous anode. The transport model consists of a coupled system of non-linear differential equations, and is coupled to the interfacial model via reaction terms within the mass-flux balance equations. An equivalent circuit model is developed to account for those components of the DSC not explicitly included in the mathematical
model of the anode. To obtain solutions for our DSC mathematical model we develop code in FORTRAN for the numerical simulation of the governing equations. We additionally employ regular perturbation analysis to obtain analytic approximations to the solutions of the interfacial charge transfer model. These approximations facilitate a reduction in computation time for the coupled mathematical model with no significant loss of accuracy. To obtain predictions of the current generated by the cell we source kinetic and transport parameter values from the literature and from experimental measurements associated with the DSC commissioned for this study. The model solutions we obtain with these values correspond very favourably with experimental data measured from standard DSC configurations consisting of titanium dioxide porous films with iodide/triiodide redox couples within the electrolyte. The mathematical model within this thesis enables thorough investigation of the interfacial reactions and charge transport within the DSC.We investigate the effects of modified cell configurations on the efficiency of the cell by varying associated parameter values in our model. We find, given our model and the DSC configuration investigated, that the efficiency of the DSC is improved with increasing electron diffusion, decreasing internal resistances and with decreasing dark current. We conclude that transport within the electrolyte, as described by the model, appears to have no limiting effect on the current predicted by the model until large positive voltages. Additionally, we observe that the ultrafast injection from the excited dye molecules limits the interfacial reactions that affect the DSC current.
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Farrell, Troy W. "The mathematical modelling of primary alkaline battery cathodes." Thesis, Queensland University of Technology, 1998.
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Hamdi, Bilel. "Modélisation des circuits périodiques et quasi-périodiques alimentés par des sources arbitraires." Thesis, Toulouse, INPT, 2015. https://oatao.univ-toulouse.fr/25877/1/HAMDI_Bilel.pdf.
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Les réseaux d’antennes planaires sont réputés par leur grande directivité et leur facilité de mise en œuvre qui offre la possibilité d’avoir un diagramme de rayonnement commandable. Cependant l’étude globale tenant compte des différents couplages EM par une théorie électromagnétique rigoureuse nécessite un espace mémoire important et un temps de calcul considérable. Pour surmonter à ces inconvénients, nous proposons d’introduire une nouvelle approche théorique basée sur le théorème de Floquet permettant la réduction du volume d’analyse EM au niveau d’une seule cellule élémentaire. Nous allons focaliser notre étude à la détermination des termes de couplage dans une configuration répartie dans une trame presque-périodique et en particulier pour les réseaux d’antennes périodiques et quasi-périodiques alimentés par des sources arbitraires. Dans ce cas, nous utiliserons les décompositions en modes de Floquet (adaptées aux structures périodiques) pour extraire la matrice de couplage [S]. Ces décompositions sont des concepts établis de longue date et a priori démontrés par de supports théoriques solides. Par conséquent, cette analyse modale permet de simplifier la résolution du problème considéré surtout quand les éléments rayonnants sont fortement couplés. Une seule méthode numérique est adoptée afin de modéliser la structure proposée : la méthode des moments combinée avec le circuit équivalent généralisé : MoM-GEC. La validation de cette dernière sera réalisée par comparaison avec d’autres méthodes numériques exactesPlanar antenna arrays are renowned for their high directivity and ease of implementation, which offers the possibility of having a controllable radiation pattern. However the global study taking into account the different EM couplings by a rigorous electromagnetic theory requires a large memory space and a considerable computation time. To overcome these drawbacks, we propose to introduce a new theoretical approach based on the Floquet theorem allowing the reduction of the EM analysis volume at the level of a single elementary cell (basic cell). We will focus our study on the determination of coupling terms in a distributed configuration in an almost-periodic frame and in particular for periodic and quasi-periodic antenna arrays fed by arbitrary sources. In this case, we will use Floquet mode decompositions (adapted to periodic structures) to extract the coupling matrix [S]. These decompositions are concepts established for a long time and a priori demonstrated by solid theoretical supports. Consequently, this modal analysis makes it possible to simplify considerably the resolution of the problem, especially when the radiating elements are strongly coupled. A single numerical method is adopted in order to model the proposed structure: the method of moments combined with the generalized equivalent circuit: MoM-GEC. Validation of the latter will be done by comparison with other exact numerical methods
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AHMADI, DARMANI MOSTAFA. "Multiphysics Design of Interior Permanent Magnet Machines and Characterization of Innovative Hard Magnetic Material." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971120.
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Lee, Chih Long, and 李誌隆. "Electric Equivalent Circuit and Three-Dimensional Vibration Analysis for Piezoelectric Transformer." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/63803709877960876741.
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碩士國立臺灣大學
造船及海洋工程學研究所
89
Abstract In this thesis, use two model method for piezoelectric transformer, (i)The first one consist of performing the analysis with electric equivalent circuit（EEC method）. (ii) Use a more general numerical finite element method using ANSYS software. More detailedness follow: (i)Use dimension, material parameters of piezoelectric transformer model become Electric equivalent circuit, through calculate circuit get properties of piezoelectric transformer, including impedance, voltage gain, efficiency. (ii)Use finite element method simulated three-dimension structure vibration of the piezoelectric transformer. Generally, piezoelectric transformer use EEC Method to model and design, but designer have be unaware of true structure vibration of the piezoelectric transformer. In this thesis, with the help of simulated three-dimension structure vibration of the piezoelectric transformer, let designer more understand piezoelectric transformer. In the same time, keep error design for piezoelectric transformer.
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Tang, Yu-Lin, and 湯毓麟. "The Dynamic Analysis of DMFC with A Nonlinear Impedance Equivalent Circuit Model." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/54232566304253438576.
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碩士北台灣科學技術學院
燃料電池產業研發碩士專班
97
To combine with other power sources is inevitable for direct methanol fuel cell (DMFC) in most applications. The dynamic model of the DMFC for simulating or designing hybrid power system is getting more important with the growing attention to the DMFC in the world. In most present researches, dynamic models of the DMFC follow with differential equations derived from electrochemical principles, so it is relatively difficult to extend applications of these models to simulate or design hybrid power systems or fuel cell stacks. In this thesis, a dynamic equivalent circuit model which is easier to be used to simulate or design the hybrid power system or fuel cell stack is proposed. The equivalent circuit is based on three equivalent circuit models, and discussed by Muller, Randles and Ramesham. In models of Muller and Ramesham, the effect of methanol crossover is neglected. In this thesis, the author proposes a nonlinear impedance module with an inductor in series developed by matching the measured polarization I-V curve. It is found the dynamic characteristics of mass transport effect can be improved in simulations via applying the inductor in series. By using the simulation software tool Matlab/Simulink SimPower module the nonlinear impedance equivalent circuit model is applied to simulate the dynamic response of the DMFC circuit in the mode of step changed output voltage control. A DMFC single cell made of Dupont MEA Nafion®117 with cross sectional area 35cm2 is used to be references of the dynamic model. The simulation results are compared with experi- ments results and found having good coincidence.
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Chuang, Shen-Wei, and 莊紳瑋. "Improved Design and Equivalent Circuit Analysis of Flexible Arrayed Dye-Sensitized Solar Cell." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/15362230772822540062.
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碩士國立雲林科技大學
電子工程系
102
In this thesis, the dye-sensitized solar cell (DSSC) was fabricated on flexible indium tin oxide/polyethylene terephthalate (ITO/PET), and investigated effect of different designed and arrayed. Firstly, flexible arrayed dye-sensitized solar cell was fabricated as mutual electrolyte structure. Part of conductive thin films was etched that opportunity for electrolyte to contact ITO thin films was reduced, and interface impedance was reduced. According to experimental results, when distance between the electrodes was 1 mm obtained optimal, which the open circuit voltage (VOC) was 0.81 V, the short circuit current density (JSC) was 1.70 mA/cm2, and the photovoltaic conversion efficiency was 0.37 %. Transmittance of transparent conductive substrate via etching was increased, which was found in previous experiments. So that designed different distances electrodes and investigated relation of transmittance. Optimal distance of comb-electrodes was 1 mm, which the open circuit voltage was 0.77 V, the short circuit current density was 1.20 mA/cm2, the fill factor (F. F.) was 46 % and the photovoltaic conversion efficiency was 0.43 %, and the transmittance was improved about 15 %. The most significant feature of the flexible substrate is bendable, but its packaging characteristic was poor. In further, the dye-sensitized solar cell produced leaking electrolyte, so the characteristic of dye-sensitized solar cell was investigated with different compressions for packaging. The optimal compression of packaging was 4 kgf/cm, which the lowest loss weight ratio (LWR) was 0.46%.
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Bansiwal, Ashok. "Equivalent Circuit Analyses and Methods to Enhance Bandwidth of Klystron Reentrant Cavities." Thesis, 2020. https://etd.iisc.ac.in/handle/2005/4659.
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Klystron is used as an amplifier at microwave frequency range. Klystrons use cylindrical or rectangular reentrant cavities in their interaction structure. Characteristics of reentrant cavity can be defined using parameters such as resonant frequency, characteristic shunt impedance and quality factor, which can be computed either using 3D electromagnetic field solver or using equivalent circuit analysis. An equivalent circuit analysis is often preferred to quickly arrive at initial dimensions of the cavity as well as to analyse the effect of various dimensional variations on the cavity parameters.
Equivalent circuit analysis for the calculation of these parameters is available in the literature for cylindrical reentrant cavity with single beam-tunnel and single constituent material. However, practical cavities are normally made with dissimilar materials and have multiple beam-tunnels as in the case of multiple-beam klystron. A new formulation has been proposed for accounting the effects of single and multiple beam-tunnels in the calculation of cavity gap capacitance. Proposed formulation provides better estimation of resonant frequency for the cavities with multiple beam-tunnels as compared to that from the existing analysis. A new analysis has also been proposed for the calculation of unloaded quality factor of cylindrical reentrant cavity using Wheeler’s incremental inductance rule. Analysis provides estimation of quality factor within 15% deviation compared with simulations. In addition to analysing the cavities with dissimilar materials, the proposed approach provides better estimation of quality factor compared with existing approaches.
Since a similar equivalent circuit analysis was not available for the rectangular reentrant cavity, the same is proposed here through geometric approximation and analytical approaches. Both the analyses have been proposed for a rectangular reentrant cavity with circular cylindrical ferrule and operating in the TM110 mode. Unloaded quality factor has been obtained using Wheeler’s incremental inductance rule. Analyses, through geometric approximation and analytical approaches, estimate resonant frequencies within 3% and 4.5% deviations, characteristic shunt impedance within 17% and 13% deviations, and unloaded quality factor within 15% and 14% deviations, respectively, compared with 3D electromagnetic simulations. The proposed analyses have also been validated against measurements and a good agreement has been obtained.
Klystrons inherently suffer from bandwidth limitation and a lot of research is going on to enhance its instantaneous bandwidth. Bandwidth of klystron depends primarily on the quality factor of the output cavity circuit. Here, three methods for enhancing the bandwidth of a klystron have been proposed. The first method utilises tailoring the surface roughness, by which the unloaded quality factor of the cavities could be reduced by a maximum of 48%. In the second method, a ridge-loaded rectangular and cylindrical reentrant cavity has been proposed where the quality factor could be reduced by maximum of 80%. In the third method, a post-loaded rectangular reentrant cavity has been proposed to have even higher reduction in the quality factor (upto 90%). Measurements have been carried out on unloaded, ridge-loaded and post-loaded rectangular reentrant cavities for the validation of proposed methods. Measured unloaded quality factors have been found within 10% deviations compared with those obtained through the simulations.
Equivalent circuit analyses and methods for reducing the quality factor of reentrant cavities proposed in the thesis will be useful for klystron designers to arrive at preliminary geometrical parameters of cylindrical or rectangular reentrant cavities with dissimilar constituent materials and to bolster their efforts to meet broadband operation.Defense Research and Development Organization (DRDO)
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Yang, Cheng-Jung, and 楊承融. "Optoelectronic Characteristics and Equivalent Circuit Analysis of Arrayed Electrochromic Display Based on Tertiary Colors." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/31546042838835453653.
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碩士國立雲林科技大學
電子工程系
102
In this thesis, the poly(3-methylthiophene) (PMeT) and the polyaniline (PANI) of the electrochromic thin films had been deposited on the zinc oxide nanowires/indium tin oxide/glass (ZnO nanowires/ITO/Glass) substrate by cyclic vltammetry (CV). First, the ZnO seed-layer was deposited on ITO/Glass by RF sputtering to investigate uniformity with different deposition mothods. Second, the ZnO nanowires were grown on the ZnO seed-layer by chemical bath deposition (CBD), which were investigated aspect ratio for different growth time. The PANI and PMeT thin films were deposited on ITO/Glass and ZnO nanowires/ITO/Glass by cyclic vltammetry. The electrochromic thin films ZnO nanowires/ITO/Glass was analyzed optical and electrochemical properties by photonic spectrometer, electrochemical impedance spectroscopy (EIS) and cyclic vltammetry, we found that the PANI and PMeT thin films was deposited for 9 hours on ZnO nanowires/ITO/Glass, which have the best transmittance variation (∆T550 nm=38 %) and optical density change (∆OD550 nm = 0.462), and the response time are 10 sec (T550 nm), 24 sec (T450 nm) and 28 sec (T650 nm). The chromaticity coordinates of PANI and PMeT thin films which deposited on ITO/Glass has the best shape of tracks.
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Chang, Meng-Ting, and 張孟婷. "Analysis of Spectrum and Discharging Behavior of Lithium-ion Battery Using Equivalent Circuit Model." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/51394267058925332726.
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碩士國立臺灣大學
應用力學研究所
102
Many studies of lithium-ion battery (LIB) has been carried out because of the wide use of it. Cost reduction, performance improvement, increase of power, excellent cycle life along with high safety are the main targets of those studies. During the process of LIBs research, it is important to inspect the inner condition of LIBs by making battery examinations. Electrochemical Impedance Spectroscopy (EIS) is one of the commonly used examinations, which is a nondestructive testing and famous for its rapidity. In this thesis, the EIS measurement was performed to obtain the spectra of LIBs. In addition, we simulated the spectra through the equivalent circuit model (ECM) of LIBs. In order to simulate the spectra precisely, we established a simulation method based on electrochemistry and mathematics. Besides, the parameters of the ECM, which were obtained from the simulation results, were analyzed and studied for understanding the effects on the impedance of LIBs caused by different experimental settings. Furthermore, one of the parameters in the ECM helped us gain an important electrochemical parameter--the diffusion coefficient of lithium-ion, which was critical for establishing electrochemical model of LIBs. The equivalent circuit model of LIBs could be further used to simulate the discharging behavior of LIBs. We also provided a method for estimating open-circuit voltage (OCV) of LIBs. This method could successfully predict the OCV of LIBs and thus decrease the time consumed during OCV measurement.
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WANG, SHI-JIE, and 王世杰. "Steady-state analysis of induction motors by a combined finite element-equivalent circuit method." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/93099151918966892925.
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Mukherjee, Pritam. "Construction Of Equivalent Circuit Of A Single Isolated Transformer Winding From Frequency Response." Thesis, 2011. https://etd.iisc.ac.in/handle/2005/2055.
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Frequency response analysis (FRA) of transformers is universally accepted as a highly sensitive tool to detect deformations in its windings. This is evident from the fact that customized commercial equipment (popularly called FRA or SFRA instruments) are used and recently the IEEE has issued a draft trial-use guide. Nevertheless, use of FRA is still limited to only detection and there is little progress towards its use for localization of winding deformation. Toward this end, a possible approach would be to compare the healthy and deformed systems in a suitable domain, e.g., their respective models could be compared. In this context, the mutually-coupled ladder network is ideally suited because not only does it map the length of the winding to sections of the ladder network, but, also inherently captures all subtle intricacies of winding behaviour under lightning impulse excitations insofar as the terminal response, internal oscillations and voltage distributions are concerned. The task of constructing a ladder network from frequency response is not trivial, and so exploration of newer methods is imperative.
A system can comprehensively be characterized by its frequency response. With this as the starting point, many approaches exist to construct the corresponding rational function (in s-domain). But, the subsequent step of converting this rational function into a physically-realizable mutually-coupled ladder network has, as yet, remained elusive. A critical analysis of the circuit synthesis literature reveals that there exists no analytical procedure to achieve this task, a fact unequivocally stated by Guillemin in his seminal book "Synthesis of Passive Networks". In recent years, use of iterative methods to synthesize such ladder networks has also been attempted with some degree of success. However, there exists a lot of scope for improvement. Based on this summary, the objectives of this thesis are as follows-
_ Development of an analytical procedure, if possible, to synthesize a mutually-coupled ladder network starting from the s-domain representation of the frequency response
_ Construction of a nearly-unique, mutually-coupled ladder network employing
constrained optimization technique and using frequency response as input, with
time-efficiency, physical realizability and repeatability as its features
In Chapter 2, analytical solution is presented to convert a given driving-point impedance function (in s-domain) into a physically-realizable ladder network with inductive couplings (between any two sections) and losses considered. The number of sections in the ladder network can vary, but, its topology is assumed fixed. A study of the coefficients of the numerator and denominator polynomials of the driving-point impedance function of the ladder network, for increasing number of sections, led to the identification of certain coefficients, which exhibit very special properties. Generalized expressions for these specific coefficients have also been derived. Exploiting their properties, it is demonstrated that the synthesis method essentially turns out to be an exercise of solving a set of linear, simultaneous, algebraic equations, whose solution directly yields the ladder network elements. The proposed solution is novel, simple, and guarantees a unique network. Presently, the formulation can synthesize a unique
ladder network up to 6-sections. Although it is an analytical solution, there are issues which prevent its implementation with actual FRA data.
Keeping the above aspect in mind, the second part of the thesis presents results
of employing an artificial bee colony search algorithm for synthesizing a mutuallycoupled lumped-parameter ladder network representation of a transformer winding, starting from its measured magnitude frequency response. The bee colony algorithm is modified by defining constraints and bounds to restrict the search-space and thus ensure synthesis of a nearly-unique ladder network, corresponding to each frequency response. Ensuring near-uniqueness while constructing the reference circuit (i.e., a uniform healthy winding) is the objective. The proposed method is easy to implement, time-efficient, ensures physical realizability and problem associated with supply of initial guess in existing methods is circumvented. Experiments were performed on two types of actual, single, isolated transformer windings (continuous-disc and interleaveddisc) and the results are encouraging.
Further details are presented in the thesis.
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Mukherjee, Pritam. "Construction Of Equivalent Circuit Of A Single Isolated Transformer Winding From Frequency Response." Thesis, 2011. http://etd.iisc.ernet.in/handle/2005/2055.
Full textAbstract:
Frequency response analysis (FRA) of transformers is universally accepted as a highly sensitive tool to detect deformations in its windings. This is evident from the fact that customized commercial equipment (popularly called FRA or SFRA instruments) are used and recently the IEEE has issued a draft trial-use guide. Nevertheless, use of FRA is still limited to only detection and there is little progress towards its use for localization of winding deformation. Toward this end, a possible approach would be to compare the healthy and deformed systems in a suitable domain, e.g., their respective models could be compared. In this context, the mutually-coupled ladder network is ideally suited because not only does it map the length of the winding to sections of the ladder network, but, also inherently captures all subtle intricacies of winding behaviour under lightning impulse excitations insofar as the terminal response, internal oscillations and voltage distributions are concerned. The task of constructing a ladder network from frequency response is not trivial, and so exploration of newer methods is imperative.
A system can comprehensively be characterized by its frequency response. With this as the starting point, many approaches exist to construct the corresponding rational function (in s-domain). But, the subsequent step of converting this rational function into a physically-realizable mutually-coupled ladder network has, as yet, remained elusive. A critical analysis of the circuit synthesis literature reveals that there exists no analytical procedure to achieve this task, a fact unequivocally stated by Guillemin in his seminal book "Synthesis of Passive Networks". In recent years, use of iterative methods to synthesize such ladder networks has also been attempted with some degree of success. However, there exists a lot of scope for improvement. Based on this summary, the objectives of this thesis are as follows-
_ Development of an analytical procedure, if possible, to synthesize a mutually-coupled ladder network starting from the s-domain representation of the frequency response
_ Construction of a nearly-unique, mutually-coupled ladder network employing
constrained optimization technique and using frequency response as input, with
time-efficiency, physical realizability and repeatability as its features
In Chapter 2, analytical solution is presented to convert a given driving-point impedance function (in s-domain) into a physically-realizable ladder network with inductive couplings (between any two sections) and losses considered. The number of sections in the ladder network can vary, but, its topology is assumed fixed. A study of the coefficients of the numerator and denominator polynomials of the driving-point impedance function of the ladder network, for increasing number of sections, led to the identification of certain coefficients, which exhibit very special properties. Generalized expressions for these specific coefficients have also been derived. Exploiting their properties, it is demonstrated that the synthesis method essentially turns out to be an exercise of solving a set of linear, simultaneous, algebraic equations, whose solution directly yields the ladder network elements. The proposed solution is novel, simple, and guarantees a unique network. Presently, the formulation can synthesize a unique
ladder network up to 6-sections. Although it is an analytical solution, there are issues which prevent its implementation with actual FRA data.
Keeping the above aspect in mind, the second part of the thesis presents results
of employing an artificial bee colony search algorithm for synthesizing a mutuallycoupled lumped-parameter ladder network representation of a transformer winding, starting from its measured magnitude frequency response. The bee colony algorithm is modified by defining constraints and bounds to restrict the search-space and thus ensure synthesis of a nearly-unique ladder network, corresponding to each frequency response. Ensuring near-uniqueness while constructing the reference circuit (i.e., a uniform healthy winding) is the objective. The proposed method is easy to implement, time-efficient, ensures physical realizability and problem associated with supply of initial guess in existing methods is circumvented. Experiments were performed on two types of actual, single, isolated transformer windings (continuous-disc and interleaveddisc) and the results are encouraging.
Further details are presented in the thesis.
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Chen, Yi-Shien, and 陳逸仙. "900/1800MHz dual-band ceramic chip antenna bandwidth improvement and equivalent circuit simulation and analysis." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/72864772524722411677.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
93
Abstract The designs of dual-band and small antennas are widely proposed in national/international microwave conferences and academic journals.[1][2] It reveals that these two kinds of design already become important trend. Because of reducing antenna size, the antenna bandwidth would decrease. In this thesis, we take advantage of Low Temperature Co-fired Ceramic[3][4]to realizeλ/4 helical antenna instead of λ/4 monopole and hope to minimize antenna size.(antenna size= 13mm*5.25mm*1.2mm) Then we add monopole in theλ/4 helical antenna. In this way，this kind of antenna would have two independent resonance paths to produce dual-band operation .Then we add another two parasitic antenna to enhance the second mode bandwidth and adjust these three monopole antenna length and the distance of each other .Trying to make these two mode closer in high band for wider bandwidth effect. This skill could make the second mode bandwidth of our chip antenna to achieve 360MHz(could cover DCS band)[5].The average gain in low band is-6.23dBi and the average gain[6] in high band is -6.56dBi.In this way, the chip antenna could fit to these two kinds of trend. At the same time, we set up equivalent circuit modal according to transmission line theory. We hope the circuit modal could analyze the chip antenna correctly and expect to acquire more information of the antennas operation principles through the discussions of circuit models. We could take advantage of circuit modal to predict chip antenna practical measurement and strengthen circuit modal function in antenna design to reduce fabrication times and E-M simulation mistake and error. * Student: Yi-shien Chen ** Advisor: Wen-Shi Lee
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ASTORINO, MARIA DENISE. "Wideband equivalent-circuit model analysis, realization and time-domain spectroscopy characterization of terahertz periodic metamaterial devices." Doctoral thesis, 2019. http://hdl.handle.net/11573/1223931.
Full textAbstract:
In my PhD thesis, I have thoroughly researched THz periodic metamaterial devices by dealing with all the phases of their development: electromagnetic analysis, design, fabrication, characterization, and data post-processing. Initially, for the analysis and design phases, I have adopted an analytical/numerical perspective for the retrieval of the devised circuit topologies. In particular, I have developed and applied equivalent circuit models and parametric macromodels for the physical investigation and optimization of the devices; these methods have been validated by proving their efficiency and effectiveness through the comparison with finite-element method based simulations. Also, they guarantee a wider range of applications in terms of frequency spectra, complexity of geometrical shapes, and material characteristics. For the realization phase, I have used a heuristic procedure of micro-fabrication and after evaluating possible non-idealities, I have made tolerance studies in order to obtain a stable electromagnetic performance. For the characterization of the flexible devices, I have used custom THz-TDS setups for both reflection and transmission-modes; the resulting configurations have proved to be compact and interesting also for further integration in embedded measurement systems. For the data analysis phase, I have post-processed the acquired measurements by implementing retrieval procedures of the constitutive parameters of the samples. Other than topics specifically related to the THz field, I have developed some models of analytical/numerical character for the study of scatterers with discontinuous impedance boundary conditions.
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Wijeweera, Don Gayan Prabath. "Development of an equivalent circuit of a large power system for real- time security assessment." 2016. http://hdl.handle.net/1993/31927.
Full textAbstract:
More and more system operators are interested in calculating transfer capability in real-time using real-time power flow models generated from the Energy Management System (EMS). However, compared to off-line study models, EMS models usually cover only a limited portion of the interconnected system. In most situations, it is not practical to extend the EMS model to capture the impact of the external systems and therefore using an equivalent network becomes necessary.
The development of equivalent circuits to represent external areas was a topic discussed over the last 50 years. Almost all of these methods require impedance information about the external area to develop the equivalent circuit. Unfortunately utilities do not have the external impedance information in the real-time. Therefore, normal industry practice is to use off-line studies to develop an equivalent circuit and use that circuit in the real-time operation without any validation. This can result in errors in the security assessment. Therefore, power industry need a method to develop or validate an equivalent circuit based on the available real-time information. This thesis work is focussed on meeting that industry need.
The work on this thesis presents two new methods that can be used to generate an equivalent circuit based on the boundary conditions. This method involves calculating equivalent impedance between two areas based on the boundary stations voltages, voltage angles and power leaving the boundary stations into external areas.
This thesis uses power system simulation between two areas to change the system condition to obtain different boundary bus voltages, voltage angles and power injections to generate necessary data. Regression analysis and least square method is then used to generate the equivalent circuit using these data. It is expected that system changes will provide necessary information in the real-time to generate the equivalent circuit.
The proposed methodology is validated with modified three area 300 bus system as well as using Manitoba Hydro’s system. Contingency analysis, transfer level calcula-tion and PV curves analysis is used to validate the proposed method. Simulation results show that the proposed method produces adequate accuracy in comparison with detailed off-line system models.
The main advantage of the proposed method as compared to other existing meth-ods such as Ward and REI is that the proposed method does not require external imped-ance information to generate the equivalent circuit. The ability to generate reasonably good equivalent circuit only using available boundary information will help utilities to generate or validate the equivalent circuit based on the current system conditions, which will intern help improve the accuracy of the security assessmentFebruary 2017
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Huang, Ghi-Hong, and 黃志宏. "Unique Determination of the Small-signal Equivalent Circuit & Analysis of the Large-signal Behavior for Uniform-Doped MESFET." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/44177097433593500203.
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Jhang, Wun-Siang, and 張文祥. "Analysis and Establishment of the Equivalent Circuit Model for the Single-Phase Brushless DC Motor by Finite-Element Method." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/28528673842380617409.
Full textAbstract:
碩士國立雲林科技大學
電機工程系碩士班
94
The thesis mainly uses the finite-element method (FEM) to simulate the properties of magnetic fields and electrical circuits for the single-phase brushless dc motor. In addition, the author makes the complete analysis for the inductance of the motor and utilizes the related results computed by FEM to establish three kinds of simulation models for the motor driving system. In the analyses of magnetic fields and electrical circuits, the distribution of static magnetic fields and the waveform of the cogging torque are simulated. Then the properties of electrical circuits including the inductance, back EMF voltage, and the actual condition of the motor operated at constant speed are simulated. The simulation results of electrical circuits are compared with the measurement results in order to understand the accuracy of the simulation. In addition, a single-phase brushless dc motor needs the asymmetric stator structure to obtain the starting torque, so the thesis also discusses the further effect of the asymmetric stator. In the former analysis of the inductance, it doesn’t consider the effects of the rotor angle and coil current, so the author makes the further analysis about their affection. The symmetric condition of the magnetic fields is utilized to derive the corresponding results in order to reduce the computing time of simulation. At last, the related results computed by FEM are used to establish the three kinds of simulation models for the single-phase brushless dc motor driving system. The simulation results for the three kinds of models are finally compared with the measurement results and the comparative accuracy among them can be obtained from the related comparison.
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Chen, Huang-Hua, and 陳皇華. "Fabrication of Dye-Sensitized Solar Cells with Modified Photoelectrode by Ag, GO, TiO2 Fibrous Nanocomposites and EIS Measurement as well as Equivalent Circuit Analysis." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/cz4634.
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LIN, YU-JEN, and 林俞任. "Investigation on Equivalent Circuit Analysis of Large-area Arrayed TiO2/ZnO Dye-sensitized Solar Cell Modified by Graphene Integrated with Magnetic Beads and Study on Wireless-based Remote Real-time Monitoring System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/rsa2ju.
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LIN, SI-HONG, and 林思宏. "The Study of Differential Reference Electrodes on Characteristics and Equivalent Circuit Impedance Analysis of the Flexible Arrayed Glucose and Ascorbic Acid Biosensors Based on AZO and ZnO Modified by Magnetic Beads and Graphene Oxide, and Integrated with Microfluidic Framework, and the Design of Readout Circuit." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/v2cgb5.
Full textAbstract:
碩士國立雲林科技大學
電子工程系
107
In this thesis, the silver reference electrodes and conductive wires were printed onto a polyethylene terephthalate substrate (PET) by using screen printing technology. Next, aluminium-doped zinc oxide (AZO) or zinc oxide (ZnO) was deposited onto the silver electrodes by using the vacuum radio frequency (RF) sputtering system. The enzyme like glucose oxidase (GOx) or ascorbate oxidase (AO) was immobilized on the AZO or ZnO membranes to fabricate the glucose biosensor or the ascorbic acid biosensor, respectively. After that, graphene oxide (GO) and magnetic beads (MBs) were used to modify the sensing membranes. In terms of the analysis of sensing characteristics, average sensitivity, linearity, response time, limit of detection, drift, hysteresis, interference, lifetime, and temperature effects were investigated. Moreover, electrochemical impedance spectroscopy (EIS) was used to analyze the electrochemical impedance of different membranes. Finally, the sensing characteristics of the biosensor integrating with the microfluidic framework were analyzed, and the wireless sensing system based on ZigBee protocol integrating the biosensor was applied to realizing remote monitoring.
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Zu-Cheng, Li, and 黎祖成. "A Comprehensive Parasitic RLC Extraction Method and Equivalent Circuit Model for High Frequency and RF Noise Analysis and Simulation in Multi-finger and Multi-ring nMOSFETs with Layout Dependent and Technology Scaling Effects." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/e538m3.
Full textAbstract:
碩士國立交通大學
電子研究所
107
In this thesis, an extensive investigation has been carried out on the layout dependent effects in multi-finger (MF) and multi-ring (MR) nMOSFETs, and the impact on high frequency performance like most importantly unit gain cut-off frequency fT and maximum oscillation frequency fMAX, as well as RF noise in nanoscale CMOS technologies. A comprehensive extraction flow has been developed for accurate determination of the intrinsic device parameters as well as intrinsic parasitic resistances, inductances, and capacitances (RLC), which are key parameters governing fT and fMAX, and RF noise like NFmin and Rn. The impact of technology scaling on high frequency device parameters and performance appears as another critically important topic. In this thesis, 90nm and 40nm CMOS technologies from TSMC, namely TN90GUTM and TN40G have been adopted for MF and MR nMOSFETs design and fabrication. The aggressive scaling of layout rule and physical dimensions like poly gate length (Lg), poly gate thickness (TPO), contact plug thickness (TCO), and metal thickness (TM1) by around 52~60%, gate oxide thickness (Tox) by around 84%, and PO-to-CO space (LPO-CO) by 42~43% from TN90GUTM to TN40G will lead to complicated influence on the intrinsic device parameters, intrinsic parasitic RLC, and more importantly high frequency performance. Basically, the shrinkage of Lg, TPO, TCO, TM1, and layout dimensions can lead to the increase of gate resistance (Rg), contact resistance, and source parasitic resistance as well as inductance (RS and LS,int) in MF devices with extended source line, all of which may cause the penalties such as degradation of transconductance (gm), fT and fMAX, and even worse the increase of RF noise (Rn and NFmin). On the other hand, the scaling of Lg, TPO, TCO, and TM1 can help suppress the intrinsic parasitic capacitances like gate sidewall and finger-end fringing capacitances (Cof and Cf(poly-end)) and achieve smaller gate capacitance (Cgg). The experimental results indicate that more aggressive scaling in Lg than Tox (or Tox(inv)) can achieve higher gm and smaller Cgg, and thus significant boost of fT by around 60 ~110% in MF nMOSFETs attributed to technology scaling from TN90GUTM to TN40G. However, the higher fT cannot guarantee the higher fMAX because that the dramatic increase of Rg may overwhelm the advantage of fT and result in similar or even lower fMAX. It means that the complicated trade-off between the parasitic RLC associated with technology scaling and layout dependent effects becomes a valuable and challenging topic for high frequency devices design, parasitic RLC extraction, and equivalent circuit modeling. In this thesis, a new method, namely matrix method for accurate extraction of extrinsic source and drain parasitic resistances, RS and RD in MF and MR MOSFETs, has been developed and proven with sufficient accuracy for effective mobility eff extraction in MF and MR nMOSFETs associated with TN90GUTM and TN40G technologies. This matrix method can accurately determine the current through every active channel (OD) finger and voltage at each source finger terminal, and thus solve the problem from previous assumption of uniform current distribution and equal source terminal voltage at every finger. The mentioned assumption may lead to sever over-estimation of extrinsic RS and an abnormal jump of eff extracted from MF nMOSFETs in case of larger finger number (NF). This problem becomes particularly worse in TN40G technology than TN90GUTM, due to the aggressive scaling of TM1~M3 and TCO, as well as significant increase of the metal sheet resistance and contact resistance (RCO). Furthermore, how to determine the physical Rg and real Rg through high frequencies responsible for fMAX, Rn, and NFmin becomes a challenging topic of controversy, particularly for MF and MR devices with extremely narrow finger width (WF) in case of very large NF. MR devices proposed as a solution for higher eff attributed to suppression of STI compressive transverse stress ⊥. However, some potential problems like the increase of Rg, Cof, and Cf(poly-end) may be detrimental to fT, fMAX, and RF noise (Rn, and NFmin). Some innovative MR layouts for simultaneous reduction of Rg, Cof, and Cf(poly-end) emerge as another topic worthy of further study. In addition, the intrinsic parasitic inductances like Lg,int, Ld,int, and Ls,int appear as critical elements with sophisticated layout dependence and influence on high frequency parameters, which are dispensable for actual intrinsic MOSFET models for high frequency simulation aimed at mm-wave circuits design. Finally, the actual intrinsic MOSFET models can be integrated with our proprietary lossy substrate model to build up a full equivalent circuit model for both high frequency and RF noise simulation prior to deembedding. However, the aggressive thickness reduction of the stacked metal layers and inter-metal dielectric in technology scaling from TN90GUTM to TN40G causes dramatic increase of parasitic capacitances associated with the GSG pads and interconnection lines from the pads to the core devices. This kind of extrinsic parasitic capacitances may overwhelm the intrinsic channel and frigning capacitances (Cgg,int, Cof,, and Cf(poly-end)), which may lead to very minor difference between various MF layouts and difficulty in open deembedding. As a result, the intrinsic Y-parameters reveal anomalous frequency dependence and reverse of positive/negative sign. It emerges as a new challenge to precise deembedding and suggests more extensive research effort in the future for effective reduction of the extrinsic parasitic capacitances. To the end, our proprietary lossy substrate deembedding method can be applied for accurate extraction and simulation of intrinsic RF noise in MF and MR devices associated with TN90GUTM and TN40G technologies. This way can eliminate the problems of conventional noise correlation matrix method and facilitate device layouts optimization for high frequency and low noise design in nanoscale CMOS technologies.
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(9755702), Tyler James Shelly. "PARAMETRIC ANALYSIS AND OPTIMIZATION OF LONG-RANGE BATTERY ELECTRIC VEHICLE THERMAL MANAGEMENT SYSTEMS." Thesis, 2020.
Find full textAbstract:
Due to increasing regulation on emissions and shifting consumer preferences, the wide adoption of battery electric vehicles (BEV) hinges on research and development of technologies that can extend system range. This can be accomplished either by increasing the battery size or via more efficient operation of the electrical and thermal systems. This thesis endeavours to accomplish the latter through comparative investigation of BEV integrated thermal management system (ITMS) performance across a range of ambient conditions (-20 °C to 40 °C), cabin setpoints (18 °C to 24 °C), and six different ITMS architectures. A dynamic ITMS modelling framework for a long-range electric vehicle is established with comprehensive sub models for the operation of the drive train, power electronics, battery, vapor compression cycle components, and cabin conditioning. This modelling framework is used to construct a baseline thermal management system, as well as for adaptation to four common systems. Additionally, a novel low-temperature waste heat recovery (LT WHR) system is proposed and shown to have potential benefits at low ambient temperatures through the reduction of the necessary cabin ventilation loading. While this system shows performance improvements, the regular WHR system offers the greatest benefit for long-range BEV drive cycles in terms of system range and transient response. With an optimal thermal management system found for long range BEV’s this system is then used as a boundary condition for a study on cooling of the battery. Battery conditioning, health, and as a result their along cell and system lifetime remains an additional concern of consumers as well as thermal systems engineers seeking to ensure safety and ensure longevity of EV battery cells. Three typical coolant flow orientations are studied to compare them under different flow conditions and thermal interface material performance. The battery cooling model is then coupled to the previously established dynamic modelling environment to demonstrate the added modelling capability (and necessity) for incorporating module-level cooling performance in both battery cooling studies and transient ITMS environments.
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Tang, X., Qichun Zhang, X. Dai, and Y. Zou. "Neural membrane mutual coupling characterisation using entropy-based iterative learning identification." 2020. http://hdl.handle.net/10454/18180.
Full textAbstract:
YesThis paper investigates the interaction phenomena of the coupled axons while the mutual coupling factor is presented as a pairwise description. Based on the Hodgkin-Huxley model and the coupling factor matrix, the membrane potentials of the coupled myelinated/unmyelinated axons are quantified which implies that the neural coupling can be characterised by the presented coupling factor. Meanwhile the equivalent electric circuit is supplied to illustrate the physical meaning of this extended model. In order to estimate the coupling factor, a data-based iterative learning identification algorithm is presented where the Rényi entropy of the estimation error has been minimised. The convergence of the presented algorithm is analysed and the learning rate is designed. To verified the presented model and the algorithm, the numerical simulation results indicate the correctness and the effectiveness. Furthermore, the statistical description of the neural coupling, the approximation using ordinary differential equation, the measurement and the conduction of the nerve signals are discussed respectively as advanced topics. The novelties can be summarised as follows: 1) the Hodgkin-Huxley model has been extended considering the mutual interaction between the neural axon membranes, 2) the iterative learning approach has been developed for factor identification using entropy criterion, and 3) the theoretical framework has been established for this class of system identification problems with convergence analysis.
This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 51807010, and in part by the Natural Science Foundation of Hunan under Grant 1541 and Grant 1734.
Research Development Fund Publication Prize Award winner, Nov 2020.
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KO, CHENG-CHU, and 柯承初. "Investigation of Photovoltaic Properties and Equivalent Circuit Impedance Analysis for Dye-sensitized Solar Cell Based on AZO Photoanode and Pt Counter Electrode Modified by Reduced Graphene Oxide under Low Illumination, and Study in Series-Parallel Connection Modules." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/86nyah.
Full textAbstract:
碩士國立雲林科技大學
電子工程系
107
In this thesis, the dye-sensitized solar cells (DSSCs) were fabricated on fluorine doped tin oxide (FTO) glass or flexible indium tin oxide/ polyethylene terephthalate (ITO/PET). The photoanode was double layer structure. Firstly, we deposited the Al-doped zinc oxide (AZO) seed layer on FTO glass by sputter system and then grew the zinc oxide (ZnO) nanorods on the AZO seed layer by hydrothermal method. Finally, we deposited the titanium dioxide (TiO2) on ZnO nanorods by the doctor blade method, the photoanode had been finished. The ZnO nanorods could increase the dye adsorption. In the other part, the platinum (Pt) modified is by reduced graphene oxide (rGO). The rGO is two-dimensional materials, which has a high surface and area-to-volume ratio. The rGO was deposited on platinum counter electrode by the doctor-blade method and it can enhance the electrocatalytic activity of the counter electrode. Finally, we measured the current density-voltage curves of the dye-sensitized solar cell (DSSCs), used electrochemical impedance spectroscopy (EIS) to measure impedance and used field emission scanning electron microscopy (FE-SEM) to observe surface morphology of the DSSCs. This new structure could make dye absorbed in a photoanode increase. We know the current situation by ultraviolet-visible spectroscopy. Consequently, This produced an increase in the photoanode ability to absorb the dye, which in turn increased the cell’s short circuit current density, raising the photovoltaic conversion efficiency from 3.71% to 4.87%. In addition, we made the DSSCs module which connected 2 devices in series and 2 devices in parallel and performed the stability analysis. In addition, The DSSCs was measured under the different light intensities. Corresponding to the results, when the light intensity was reduced from 100 mW/cm2 to 30 mW/cm2, the fill factor and the photovoltaic conversion efficiency were increased from 52.85 % to 63.45 % and 4.01 % to 5.25 %, respectively. The photovoltaic conversion efficiency was grown up to 7.82 % when the DSSCs were operated under T5 fluorescent light which light intensities were 0.2 mW/cm2 - 1.7 mW/cm2.
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YOU, PEI-HONG, and 游培弘. "Investigation on the Photovoltaic Characteristics of Flexible Arrayed TiO2 Dye-sensitized Solar Cell Modified by Graphene and Magnetic Beads Integrated with ZnO Nanowires under the Low Illumination and Study on Impedance Analysis of Large-area Series-parallel Equivalent Circuit." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/xc2mb5.
Full textAbstract:
碩士國立雲林科技大學
電子工程系
105
In this thesis, we focused on the performance improvement of dye-sensitized solar cell (DSSC). First, the zinc oxide nanowires was deposited on the different substrates by using water bath method, such as fluorine-doped tin oxide/glass (FTO/Glass) substrate and the indium tin oxide/polyethylene terephthalate (ITO/PET) substrate. After that, the different contents of graphene oxide (GO) and magnetic beads (MBs) were incorporated into titanium dioxide, which will be deposited on the zinc oxide nanowires film by using spin coating method. The optimal incorporating ratio of GO-MBs-TiO2/ zinc oxide nanowires is investigated for the photoelectrode. On the other hand, we also analyzed the series-parallel connection modules and the effects of low illumination for the photovoltaic properties of DSSC. For optimal device, the surface morphology, film thickness, crystalline phase, the optical and photoelectric properties of composite film will be investigated by scanning electron microscope (SEM), X-ray diffractometer (XRD), UV-visible spectroscopy (UV-vis) and electrochemical impedance spectroscopy (EIS). According to the experimental results, the content of 1.5 mL GO and 0.5 mL MBs for DSSC had the optimal photovoltaic properties performances. The optimal photovoltaic conversion efficiency (η) was 4.46 %. Finally, the DSSC of optimal composite film was investigated under different light intensities, which achieved the higher η of 5.21 % a 10 mW/cm2 illumination. The impedance decreased/increased with the increasing connections of the parallel/series module, which photovoltaic conversion efficiencies were 2.81 % and 4.21%, respectively. When use the large area module (2 series + 2 parallel), which η was 3.02%. The optimal η was 3.93% under 10 mW/cm2 illumination.