Dissertations / Theses on the topic 'Switching machines'
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Zulu, Ackim. "Flux switching machines using segmental rotors." Thesis, University of Newcastle Upon Tyne, 2010. http://hdl.handle.net/10443/1070.
Full textGuardado, J. L. "Computer models for representing electrical machines during switching transients." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521481.
Full textIcli, Burcak. "Towards Autonomous Molecular Machines: Switching Coupled To An Oscillating Reaction." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608749/index.pdf.
Full textChen, Anyuan. "Investigation of Permanent Magnet Machines for Downhole Applications : _ Design, Prototype and Testing of a Flux-Switching Permanent Magnet Machine." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11829.
Full textForster, Andrew E. "Energy Harvesting From Exercise Machines: Buck-Boost Converter Design." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1702.
Full textNasr, Andre. "Nouvelles structures de machines électriques pour la génération embarquée avionique." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN065.
Full textThis work addresses the subject of the embedded electric generation in future aircraft. The main objective is to find a new electrical machine structures that can meet the new avionic requirements. We have been particularly interested in a Hybrid Excited Flux Switching machine with a Magnetic Bridge (HEFSMMB). The structure of this machine has several advantages such as static excitation sources, a passive rotor and a unique stator structure which makes it possible to have a low residual voltage, thus respecting the safety constraints. We have presented in the first chapter a state of the art on singly and doubly excited flux switching machines. We have also given the rules which define the choice of the number of stator and rotor poles. Chapter 2 was devoted to study the electromagnetic performances of the HEFSMMB using a finite element model. This model has been validated by experimental measurements carried out on a 3 kW prototype. In the final chapter, we have put in place an optimization methodology in order to improve the overall performances of the HEFSMMB and to limit its residual voltage. The optimization results showed much improved performances. It can be concluded that the MCFDEPM is a good candidate to replace the three-stage machine in future aircraft
Felicetti, Roberto. "Voltage Transients in the Field Winding of Salient Pole Wound Synchronous Machines : Implications from fast switching power electronics." Licentiate thesis, Uppsala universitet, Elektricitetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-434652.
Full textCalmels, Dorothea [Verfasser], and Hans [Akademischer Betreuer] Ziegler. "Job Sequencing and Tool Switching Problems with a Generalisation to Non-Identical Parallel Machines / Dorothea Calmels ; Betreuer: Hans Ziegler." Passau : Universität Passau, 2020. http://d-nb.info/1218780703/34.
Full textLovgren, Nicholas Keith. "Energy Harvesting From Exercise Machines: Forward Converters with a Central Inverter." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/520.
Full textBen, Sedrine Emna. "Machines à commutation de flux à grand nombre de phases : modèles comportementaux en mode dégradé et élaboration d’une stratégie de commande en vue de l’amélioration de la tolérance aux pannes." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0047/document.
Full textIn this thesis, we are interested in the study of a five-phase flux switching permanent magnet machine (five-phase FSPM machine) behavior in healthy and faulty mode. First, a comparison of electromagnetic performances between this machine and an equivalent three-phase machine is carried out. These performances are calculated by a Finite Element (FE 2D) model and validated by experiments. Results showed the five-phase machine contribution with a higher torque density, lower torque ripples, lower short-circuit current and ability to tolerate phases faults. The study of open-circuit tolerance is then developed for this five-phase FSPM. The behavior of the machine (the average torque, torque ripples, copper losses and the current in the neutral) in the case of open-circuit on a single and two adjacent and non-adjacent phases is presented. Then reconfiguration methods to improve the operation are proposed including a minimum reconfiguration allowing to end up with a feeding equivalent to that of a three-phase or a four-phase machine, an analytical calculation of optimal currents to cancel both the neutral current and torque ripples while ensuring the average torque, and finally a reconfiguration performed by a genetic optimization algorithm which is a non-deterministic algorithm multi-objective functions and multi-constraints. In this context, various combinations of different objectives and constraints are proposed and optimal currents are injected into the 2D FE model of the machine to see if performances have been improved. The analytical model of the torque used in the optimization algorithm is then revised to take into account the influence of the degraded mode. Different solutions of Pareto front are analyzed and electromagnetic performances are improved. This is verified by FE 2D calculations and followed by experimental validation. Faults impact on the radial magnetic forces is also analyzed. In the second part of this work, the study of the five-phase FSPM machine tolerance to short-circuit faults is performed. First steps of the faults isolation are proposed. Thereafter, short-circuit currents, taking into account the reluctance machine impact, are calculated analytically and their effects on machine performances are analyzed. Reconfigurations are also calculated by the genetic algorithm optimization and new references currents improved the degraded mode operation. All results are validated by the FE 2D calculation and experimentally. In conclusion, comparisons between fault-tolerance to phases openings and short-circuits of the five-phase FSPM machine are performed. Results led to conclude regarding the operation of this machine in healthy and degraded modes with and without correction. Analytical, numerical and experimental results showed good efficiency of the proposed control to improve fault-tolerance to phases openings and short-circuits
Uslu, Mutlu. "Analysis, Design, And Implementation Of A 5 Kw Zero Voltage Switching Phase-shifted Full-bridge Dc/dc Converter Based Power Supply For Arc Welding Machines." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607873/index.pdf.
Full textVerez, Guillaume. "Contribution à l’étude des émissions vibro-acoustiques des machines électriques : cas des machines synchrones à aimants dans un contexte automobile." Thesis, Le Havre, 2014. http://www.theses.fr/2014LEHA0024/document.
Full textThe proportion of permanent magnets synchronous motors used for electric and hybrid automotive traction has exponentially increased during the past decade. This evolution comes with ever-demanding low noise and vibrations requirements. Multi-physics analysis of the motor is a decisive issue for the development of the powertrain. For the exploration of potentially efficient motor solutions in first design steps, it is thus a necessity to have at disposal fast and accurate computer codes. In this respect, acoustic and vibratory aspects are modeled using finite element and analytical models in this thesis. As a result, using an electromagnetic model, the weakly-coupled magneto-vibro-acoustic analysis (iterative solving of each physic) can be performed.The thesis is divided into four parts. The first part states the art on machine vibro-acoustic emissions and focuses on noise of magnetic origins modeling. Issues of modeling are detailed. Then, models are described to a great extent in the second part. Finite element models are favorably compared to experimental measures. A third part validates analytical models in comparison to finite element analysis, by gradually complicating the geometry of a surface permanent magnets radial flux machine. Finally, a fourth part uses finite element models to study non-conventional machines such as flux switching radial flux machines and surface permanent magnets axial flux machines
Dupas, Agathe. "Modélisation et optimisation d'une machine synchrone à commutation de flux et à double excitation à bobinage global." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN037/document.
Full textIn this thesis, a new hybrid excitation, flux-switching machine is being presented. The main feature of this device is its global winding hybrid excitation with claw poles. This solution has been explored in order to reduce the copper mass and increase excitation winding efficiency. One of the most widely used alternators in automotive applications is a claw pole alternator whose claws are located on the rotor. The prototype introduced in this study is based on the same principle yet with claws located on the stator, which allows its rotor to be passive in rotating at higher speeds without slip-rings or brushes. Furthermore, the advantages of the double excitation are cumulative.The thesis will first describe the structure and operating principles of this new hybrid excitation, flux-switching machine, For example, the no-load flux linkage and the back-electromotive force on a no-load are measured and calculated;. Moreover, the load testing of this machine will be displayed. Short-circuit currents will be calculated and measured in order to determine the output power capability while operating in generator mode. The second chapter presents finite element and analytical models which allows to determine the output power capability while operating in generator mode. And with the FEA, the no-load flux linkage is investigated, This investigation serves to highlight: the influence of the stacking factor, the B-H curve definition, and the permanent magnet residual induction value, Finally, a lumped-parameter magnetic circuit model is developed and validated by 3-D finite element analysis, The model allows estimating output power of the structure when running in generator mode (with a DBR) faster than with 3D-FEA. In addition, thanks to the model the geometry is optimized for several specifications
Boisson, Julien. "Modélisation analytique magnéto-acoustique des machines synchrones à commutation de flux à aimants permanents : optimisation du dimensionnement." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0043/document.
Full textThis thesis deals with the study of Flux-Switching Permanent-Magnets, in particular on magnetic, mechanical and acoustic behavior of these structures. Firstly, origin of noise generated has been presented with particular attention to magnetic phenomena. Exploration of magnetic stresses, mechanical and vibration analysis have been performed by finite element simulations. Secondly, an analytical multi-physics model has been presented in order to estimate magnetic, mechanical and acoustic behavior. The different models have been validated by finite element simulations or by experimental measurements. Finally, this model has been applied in a geometric optimization loop to maximize electromagnetic torque and minimize acoustic noise generated. These optimizations have been performed on 3-phases 12/10, 4-phases 16/12 and 5-phases 20/18 at fixed and variable speed
Rumi, Alberto. "Partial Discharge Inception Voltage in Converter-Fed Machines for the More Electric Aircraft." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textFares, Adnan. "Development of advanced architectures of power controllers dedicated to Ultra High Switching Frequency DC to DC converters." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS195.
Full textThe continuous sophistication of smart handheld devices such as smartphones and tablets creates an incremental need for improving the performances of the power conversion devices. The trend in power delivery migrates progressively to higher frequency, higher density of integration and flexibility of the control scheme. Dynamic Voltage Scaling Power Management ICs (DVS PMIC) are now systematically used for powering RF Transmitters and DVFS PMICS using Voltage and Frequency scaling are used for CPUs and GPUs. Flexible High frequency (HF) DC/DC converters in conjunction with low dropout LDOs constitute the main solution largely employed for such purposes. The migration toward high frequency/small size DCDC solutions creates serious challenges which are: 1) the stability of the feedback loop across a wide range of loading voltage and current conditions 2) The complexity of the control and often-non-synchronous state machine managing ultra large dynamics and bridging low power and high power operating modes, 3) The portability of the proposed solution across technology processes.The main stream solutions have so far reached the range of 2 to 6 MHz operation by employing systematically sliding mode or hysteretic converters that suffer from their variable operating frequency which creates EMI interferences and lead to integration problems relative to on-chip cross-talk between converters.In this work we aim at extend the use of traditional design and modeling techniques of power converters especially the average modeling technique by putting a particular care on the simplification of the theory and adjunction of flexible compensation techniques that don't require external components and that are less sensitive to process spread, or to high frequency substrate and supply noise conditions.The Small Signal Average Models, widely treated in the existing literature, might address most needs for system modeling and external compensation snubber design, especially when aiming on the high frequency natural zero of the output capacitor. However, HFDCDC converters today use small size MLCC capacitors with a very low ESR which require using alternative techniques mixing the compensation scheme with the duty cycle generation itself. The literature often provides a simplistic state machine description such as PWM/PFM operations but doesn't cover combined architectures of synchronous / non synchronous mode operations such as PWM, PFM, Current Limit, Boundary Clamp, Start, Transitional and finally Fault or Protection modes.In our work, we have focused our study on two main axes: 1) The parametric modeling and the loop compensation of HFDCDC and 2) the scalability of the control state machine and mode inter-operation. In the first part, we provided a detailed small signal averaged model of the “voltage and current mode buck converter” and we depicted it to emphasize and optimize the contributions of the Proportional, Integral and Derivative feedback loops. We demonstrated the ability to use the current feedback to damp and stabilize the converter with a wide variety of loading conditions (resistive or capacitive). In the second part, we provided architecture of the mode control state machine with different modes like the PWM, PFM, soft-start, current limit,… .The technique we have used is inspired by Huffman machine with a significant effort to make it abstract and scalable. The state machine is implemented using RTL coding based on a generic and scalable approach.The theoretical effort has been implemented inside a real PMIC test-chip carrying two 12MHz buck converters, each employing a voltage and current mode feedback loop. The chip has been realized in a 0.5um / 0.18um BiCMOS technology and tested through a dedicate Silicon validation platform able to test the analog, digital and power sections. The key performance obtained is a 50mV load transient undershoot / overshoot during 2us following a load step of 300mA (slope 0.3A/ns)
Asfirane, Salim. "Développement d’un outil de génération automatique des réseaux de réluctances pour la modélisation de dispositifs électromécaniques." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN065/document.
Full textIn the field of electrical machine modeling, the method that is experiencing great popularity as renowned for the quality of its results is the finite element method. However, computation time becomes important when the finite element models are associated with an optimization and predesign process as part of a complex technical specification sheet. The alternate modeling solution is the lumped parameter models approach. The latter is well suited for the individual physical domains involved in the operation of electrical machines, namely electromagnetic, mechanical and thermal. The latter is well suited for the individual physical domains involved in the operation of electrical machines, namely electromagnetic, mechanical and thermal. Thus, electric machine design routines have been used to determine the properties and performance of the latter under different operating conditions. However, the implementation of these modeling approaches requires significant development time for lack of dedicated tools such as those existing for the finite element method. In the electromagnetic context, the work of this thesis presents a contribution to the reluctance network modeling approach by developing tools allowing their automatic generation. This approach is integrated into a software tool allowing the automated processing of a geometry, providing a precise model in a shorter time than that required for the construction of a dedicated model. The tool, fully developed on MATLAB®, has been called MRNsoftware (for Mesh-based Reluctance Network Software). This dissertation contains four chapters. The first chapter is devoted to a detailed state of the art on reluctance network modeling methods. In the second chapter, we discuss the methodologies implemented based on a conformal mesh of the study space by bidirectional elementary blocks. The non-conformal mesh will be the subject of the third chapter. Magnetic scalar potential interpolation will prove useful to connect the different branches of the block elements at the edge of the non-conformal interfaces. Different mesh patterns of the same structure are tested and the accuracy as well as the evaluation time of the reluctance network models are compared with the finite element reference models. The fourth chapter presents, at first, the graphical interface of the tool. Subsequently, the developed modeling techniques are used to realize the models of the permanent magnet linear machine and the linear wound excitation linear machine. These modeling approaches are the result of the cooperation between SATIE and GREAH laboratories and are part of the general endeavor of developing multiphysics modeling tools for the optimal sizing of electromagnetic devices
Gabsi, Mohamed Khémis. "Contribution a l'etude de la commutation dans les machines a courant continu associees a des convertisseurs statiques de puissance." Paris 6, 1987. http://www.theses.fr/1987PA066170.
Full textHari, Nikita. "Gallium nitride power electronics using machine learning." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288610.
Full textReeve, John Martin. "Computer aided design, simulation and optimisation of the flux switching machine." Thesis, University of Leicester, 2002. http://hdl.handle.net/2381/30202.
Full textDarmanjian, Shalom. "Switching Hidden-Markov Model and hardware implementation for a Brain-Machine Interface." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009426.
Full textКасяненко, Артем Вікторович. "Врахування потенціалу сонячної електричної станції встановленої на даху багатоквартирного будинку при виборі елементів системи електропостачання." Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/43038.
Full textDuring the implementation of the diploma project, the calculation of the residential area, the network of which reaches more than 1 kV, was performed, and during the calculations, power transformers, automation and protection equipment were selected. In a special issue, a study was conducted on the effectiveness of installing SES on the roof of an apartment building.
Stinson, Benjamin M. (Benjamin Michael). "Nucleotide binding and conformational switching in the hexameric ring of a AAA+ machine." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/97273.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
ATP-powered proteases enforce protein quality-control and regulation in all domains of life. ClpX, a AAA+ ring homohexamer, uses the energy of ATP binding and hydrolysis to power conformational changes that unfold and translocate target proteins into the ClpP peptidase for degradation. X-ray crystal structures show that some ClpX subunits occupy nucleotide-loadable conformations and others occupy unloadable conformations. Furthermore, biochemical evidence suggests that multiple classes of nucleotide-loadable subunits exist. How asymmetry among subunits is coordinated to achieve mechanical function has remained unclear. Using a combination of mutagenesis, disulfide crosslinking, and fluorescence methods to assay the conformations and nucleotide-binding properties of individual subunits, we demonstrate dynamic interconversion of loadable and unloadable subunits. Such interconversion is required to couple ATP hydrolysis by ClpX to mechanical work, plays a role in substrate binding and ClpP interaction, and is not strictly coupled to the ATP hydrolysis cycle. ATP binding to different classes of subunits drives allosteric changes in ring conformation to allow hydrolysis and coupled machine function, and we present a subunit-specific single molecule nucleotide occupancy assay to elucidate details of this process.
by Benjamin M. Stinson.
Ph. D.
Liu, Jiamo. "Machine learning based heuristic BBU-RRH switching scheme for C-RAN in 5G." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31427.
Full textTrabelsi, Mohamed. "Contribution au diagnostic de défauts des composants de puissance dans un convertisseur statique associé à une machine asynchrone - exploitation des signaux électriques -." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4342.
Full textThe main goal of this thesis concerns the detection and identification of simple and multiple open-circuit faults in voltage source inverters (VSIs)-fed induction motor drives. In first step, the potentialities, the weaknesses as well as the uncertainties of the previously published works have been discussed. The second step was dedicated to the study of the inverter faults impact on the induction motor. For this purpose, we have proposed two methodologies permitting the characterization of the electromagnetic torque behaviour as well as the electric variables of the induction motor under the open- and short-circuit faults. These preliminary studies allowed to propose two novel signal-based approaches for open-circuit fault diagnosis in voltage source inverter. The measured outputs inverter voltages and currents have been used as the input quantities for the fault detection and identification (FDI) process. The first approach consists in analyzing the pulse-width modulation (PWM) switching signals and the line-to-line voltage levels during the switching times, under both healthy and faulty operating conditions. For this purpose, we have adopted an instantaneous representation of these variables, which permits their analysis over one switching period. The fault diagnosis scheme is achieved using simple analog device. This circuit allows an accurate single and multiple faults diagnosis, and a minimization of the fault detection time which becomes about a few tens of microseconds
Gambetta, Daniele Morco. "Sensorless technique for BLDC motors." University of Southern Queensland, Faculty of Engineering and Surveying, 2006. http://eprints.usq.edu.au/archive/00001427/.
Full textFreire, Hermelo Maria. "Amplifier control using machine learning and coloured optical packet switching node design in optical networks." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAS024.
Full textData rate and energy consumption are the major concerns in optical networks. In order to reduce energy consumption, transport operator networks based on optical circuit switching (OCS) concept, are becoming optically transparent, reducing optical to electrical (O/E) and electrical to optical (E/O) conversions. To face data rate increase, complex modulation formats and dual-polarization systems are considered and fiber spectrum is saved using network resources in a more efficient way, giving rise to a flexible frequency grid. Flexible transponders are developed to tune modulation formats and wavelengths and reconfigurable optical add/drop multiplexers (ROADMs) based on wavelength selective switches (WSSs) are studied. Flexible networks consider also a more dynamic traffic. Dynamism and flexibility lead to a deep transformation of the optical networks, including optical nodes, from both physical and control layer point of view. When channels are added and/or dropped, optical power excursion from erbium doped fiber amplifiers (EDFAs) has to be controlled dynamically. In that context, software defined networking (SDN) assisted by machine learning (ML) techniques is envisaged as promising candidate for the management and the dynamic control of optical networks. In this context, in the first part of our PhD work, we deal with optical power excursion in dynamic optical transport networks. In order to mitigate undesirable effects, we introduce and implement power excursion prediction and pre-compensation module using ML methods. As physical layer impairments (PLIs) accumulate along the path, we consider optical power excursion together with optical signal to noise ratio (OSNR) and bit error rate (BER), to estimate quality of transmission (QoT) of unseen channel configurations. Afterwards, using a reinforcement learning (RL) approach, we establish an autonomous impairment aware modulation format and wavelength assignment procedure, and we show that this permits to reduce the blocking probability of the incoming demands in optical nodes. In the second part of our PhD work, in the context of the N-GREEN project from the French national agency of research, we address a disruptive network architecture based on coloured optical packet switching (OPS). The main objective of N-GREEN is to propose a new generation of energy efficient routers. In the N-GREEN project, we perform the experimental characterization of an optical 2 x 2 switch based on semiconductor optical amplifiers (SOAs). This characterization leads to the proof of concept of a ring network with 10 nodes in cascade. Envisaging a 16 x 16 switch configuration, the experimental characterization, in single channel and WDM configurations, unveil interesting possibilities for the transmission of ultra-high data rates
Suppharangsan, Wisaruda. "A new switching technique for minimisation of DC-link capacitance in switched reluctance machine drives." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/14610/.
Full textRobert, Frédéric. "Modélisation et simulation de transformateurs pour alimentations à découpage." Doctoral thesis, Universite Libre de Bruxelles, 1999. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211897.
Full textSelon le premier axe de recherche, l'idée est d'utiliser un logiciel de simulation de champs électromagnétiques par éléments finis pour analyser les champs en deux et en trois dimensions dans le transformateur. Outre une compréhension globale de la répartition des champs, on cherche à analyser finement les pertes cuivre générées dans les enroulements.
Aux fréquences utilisées dans les alimentations actuelles (typiquement quelques centaines de kilohertz), la densité de courant se répartit en effet de manière non uniforme dans les conducteurs suite aux effets quasi statiques (effet pelliculaire et effet de proximité). Les pertes cuivre doivent donc être calculées avec des outils spécifiques qui en tiennent compte. Or les modèles analytiques classiquement utilisés dans ce but (formules de Dowell et apparentées) reposent sur une analyse unidimensionnelle du transformateur, suivant une hypothèse dont la portée est mal connue et mise en cause par plusieurs auteurs.
Grâce aux simulations par éléments finis, la thèse dresse un inventaire inédit des effets quasi¬statiques 2D et 3D dans les enroulements. Les différents effets sont expliqués physiquement. La fiabilité des méthodes 1D est analysée et l'erreur commise par celles ci est quantifiée suivant le type d'enroulement et la fréquence. Trois méthodes alternatives de calcul des pertes en deux dimensions sont également analysées et critiquées.
Pour un type précis d'enroulement (une couche de ruban entre une valeur nulle et une valeur maximale de la force magnétomotrice), une "formule semi empirique" est encore développée. Celle-¬ci rassemble en une seule expression un grand nombre de simulations couvrant toutes les situations géométriques envisageables pour le type d'enroulement considéré. On crée ainsi un outil sans équivalent actuellement, qui allie la rapidité des méthodes 1D à la précision des simulations 2D. La formule semi empirique offre de nombreux avantages pour les concepteurs, dont une forme analytique particulière et la possibilité de réaliser des études paramétriques.
D'autre part, la thèse montre également que le "facteur de remplissage", notion présente dans la plupart des formules unidimensionnelles de calcul des pertes cuivre, résulte d'une erreur dans l'article de base de Dowell et se révèle donc sans fondement théorique. Ce facteur garde néanmoins une utilité pratique par le fait qu'il reproduit fortuitement certains effets 2D.
Selon le second axe de recherche, la modélisation, divers schémas équivalents sont analysés. Compte tenu du fait que les transformateurs utilisés dans les alimentations à découpage comprennent généralement plusieurs sorties et voient des formes d'onde fortement chargées en harmoniques, deux types de schémas particuliers sont retenus: le schéma "Coupled Choke Secondaries" (schéma CCS) et les schémas du Laboratoire d'Electrotechnique de Grenoble (schémas LEG). Le schéma CCS est validé sur un transformateur réel et implémenté dans une application conviviale.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
Backlund, Alexander. "Switching hybrid recommender system to aid the knowledge seekers." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414623.
Full textEamrurksiri, Araya. "Applying Machine Learning to LTE/5G Performance Trend Analysis." Thesis, Linköpings universitet, Statistik och maskininlärning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-139126.
Full textPretorius, Dewald. "Design study and analysis of a conventional radial-field flux-switching permanent magnet machine for a medium-speed wind turbine." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33844.
Full textBardenet, Rémi. "Towards adaptive learning and inference : applications to hyperparameter tuning and astroparticle physics." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112307.
Full textInference and optimization algorithms usually have hyperparameters that require to be tuned in order to achieve efficiency. We consider here different approaches to efficiently automatize the hyperparameter tuning step by learning online the structure of the addressed problem. The first half of this thesis is devoted to hyperparameter tuning in machine learning. After presenting and improving the generic sequential model-based optimization (SMBO) framework, we show that SMBO successfully applies to the task of tuning the numerous hyperparameters of deep belief networks. We then propose an algorithm that performs tuning across datasets, mimicking the memory that humans have of past experiments with the same algorithm on different datasets. The second half of this thesis deals with adaptive Markov chain Monte Carlo (MCMC) algorithms, sampling-based algorithms that explore complex probability distributions while self-tuning their internal parameters on the fly. We start by describing the Pierre Auger observatory, a large-scale particle physics experiment dedicated to the observation of atmospheric showers triggered by cosmic rays. The models involved in the analysis of Auger data motivated our study of adaptive MCMC. We derive the first part of the Auger generative model and introduce a procedure to perform inference on shower parameters that requires only this bottom part. Our model inherently suffers from label switching, a common difficulty in MCMC inference, which makes marginal inference useless because of redundant modes of the target distribution. After reviewing existing solutions to label switching, we propose AMOR, the first adaptive MCMC algorithm with online relabeling. We give both an empirical and theoretical study of AMOR, unveiling interesting links between relabeling algorithms and vector quantization
Axehill, Daniel, and Johan Sjöberg. "Adaptive Cruise Control for Heavy Vehicles : Hybrid Control and MPC." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1604.
Full textAn Adaptive Cruise Controller (ACC) is an extension of an ordinary cruise controller. In addition to maintaining a desired set velocity, an ACC can also maintain a desired time gap to the vehicle ahead. For this end, both the engine andthe brakes are controlled.
The purpose with this thesis has been to develop control strategies for an ACC used in heavy vehicles. The focus of the work has been the methods used for switching between the use of engine and brake. Two different methods have been studied, a hybrid controller and an MPC-controller.
For the hybrid controller, the main contribution has been to use the influence of the surroundings on the acceleration of the truck. This consists of several parts such as wind drag, road slope and rolling resistance. The estimated influence of the surroundings is used as a switch point between the use of engine and brakes. Ideally, these switch points give bumpless actuator switches.
The interest in the MPC-controller as an alternative solution was to achieve automatic actuator switching, thus with no explicitly defined switch points. The MPC-controller is based on a model of the system including bounds on the control signals. Using this knowledge, the MPC-controller will choose the correct actuator for the current driving situation.
Results from simulations show that both methods solve the actuator switch problem. The advantages with the hybrid controller are that it is implementable in a truck with the hardware used today and that it is relatively simple to parameterise. A drawback is that explicit switch points between the uses of the different actuators have to be included. The advantages with the MPC-controller are that no explicit switch points have to be introduced and that constraints and time delays on signals in the system can be handled in a simple way. Among the drawbacks, it can be mentioned that the variant of MPC, used in this thesis, is too complex to implement in the control system currently used in trucks. One further important drawback is that MPC demands a mathematical model of the system.
Aksel, Fatih. "Enhancing Accuracy Of Hybrid Recommender Systems Through Adapting The Domain Trends." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612330/index.pdf.
Full texts tastes and desires are temporary and they gradually evolve. Moreover, each domain has unique characteristics, trends and unique user interests. Recent research has mostly focused on static hybridization schemes which do not change at runtime. In this thesis work, we describe an adaptive hybrid recommender system, called AdaRec that modifies its attached prediction strategy at runtime according to the performance of prediction techniques (user feedbacks). Our approach to this problem is to use adaptive prediction strategies. Experiment results with datasets show that our system outperforms naive hybrid recommender.
Shenouda, Amir. "Quasi-static hydraulic control systems and energy savings potential using independent metering four-valve assembly configuration." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07052006-143614/.
Full textWayne J. Book, Committee Chair ; Nader Sadegh, Committee Member ; Chris Paredis, Committee Member ; Bonnie Heck, Committee Member ; Roger Yang, Committee Member ; Renato D.C.Monteiro, Committee Member.
Ruíz, Hernández Diego. "Essays on indexability of stochastic sheduling and dynamic allocation problems." Doctoral thesis, Universitat Pompeu Fabra, 2007. http://hdl.handle.net/10803/7347.
Full textThe second class of problems concerns two families of Markov decision problems. The spinning plates problem concerns the optimal management of a portfolio of assets whose yields grow with investment but otherwise decline. In the model of asset exploitation called the squad system, the yield from an asset declines when it is utilised but will recover when the asset is at rest. Simply stated conditions are given which guarantee general indexability of the problem together with necessary and sufficient conditions for strict indexability. The index heuristics, which emerge from the analysis, are assessed numerically and found to perform strongly.
Mollaret, Sébastien. "Artificial intelligence algorithms in quantitative finance." Thesis, Paris Est, 2021. http://www.theses.fr/2021PESC2002.
Full textArtificial intelligence has become more and more popular in quantitative finance given the increase of computer capacities as well as the complexity of models and has led to many financial applications. In the thesis, we have explored three different applications to solve financial derivatives challenges, from model selection, to model calibration and pricing. In Part I, we focus on a regime-switching model to price equity derivatives. The model parameters are estimated using the Expectation-Maximization (EM) algorithm and a local volatility component is added to fit vanilla option prices using the particle method. In Part II, we then use deep neural networks to calibrate a stochastic volatility model, where the volatility is modelled as the exponential of an Ornstein-Uhlenbeck process, by approximating the mapping between model parameters and corresponding implied volatilities offline. Once the expensive approximation has been performed offline, the calibration reduces to a standard & fast optimization problem.In Part III, we finally use deep neural networks to price American option on large baskets to solve the curse of the dimensionality. Different methods are studied with a Longstaff-Schwartz approach, where we approximate the continuation values, and a stochastic control approach, where we solve the pricing partial differential equation by reformulating the problem as a stochastic control problem using the non-linear Feynman-Kac formula
Aboelhassan, Mustafa Osman Elrayah. "Robustní řízení synchronního stroje s permanentními magnety a spínaným tokem." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233605.
Full textMenacer, Mohamed Amine. "Reconnaissance et traduction automatique de la parole de vidéos arabes et dialectales." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0157.
Full textThis research has been developed in the framework of the project AMIS (Access to Multilingual Information and opinionS). AMIS is an European project which aims to help people to understand the main idea of a video in a foreign language by generating an automatic summary of it. In this thesis, we focus on the automatic recognition and translation of the speech of Arabic and dialectal videos. The statistical approaches proposed in the literature for automatic speech recognition are language independent and they are applicable to modern standard Arabic. However, this language presents some characteristics that we need to take into consideration in order to boost the performance of the speech recognition system. Among these characteristics we can mention the absence of short vowels in the text, which makes their training by the acoustic model difficult. We proposed several approaches to acoustic and/or language modeling in order to better recognize the Arabic speech. In the Arab world, modern standard Arabic is not the mother tongue, that is why daily conversations are carried out with dialect, an Arabic inspired from modern standard Arabic, but not only. We worked on the adaptation of the speech recognition system developed for the modern standard Arabic to the Algerian dialect, which is one of the most difficult variants of the Arabic language to recognize by automatic speech recognition systems. This is mainly due to the borrowed words from other languages, the code-switching and the lack of resources. Our approach to overcome all these problems is to take advantage from oral and textual data of other languages that have an impact on the dialect in order to train the required models for dialect speech recognition. The resulting text from Arabic speech recognition system was then used for machine translation. As a starting point, we conducted a comparative study between the phrase based approach and the neural approach used in machine translation. Then, we adapted these two approaches to translate the code-switched text. Our study focused on the mix of Arabic and English in a parallel corpus extracted from official documents of the United Nations. In order to prevent the error propagation in the pipeline system, we worked on the adaptation of the vocabulary of the automatic speech recognition system and on the proposition of a new model that directly transforms a speech signal in language A into a sequence of words in another language B
Pascal, Jean-Pierre. "Etude de circuits d'aide à la commutation de thyristors GTO montés en série pour des applications à la traction ferroviaire." Paris 6, 1986. http://www.theses.fr/1986PA066273.
Full textKhamzin, Yersin. "Technologie vstřikování zkušebních těles z termoplastů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444217.
Full textSun, Shang-Te, and 宋尚德. "A Programmable State machine based Field Extraction Engine for Content switching." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/09296734408773769454.
Full text國立雲林科技大學
電機工程系碩士班
90
With the popularity of network applications and broadband network, the traffic on the network is continuously arising. We use the server clustering architecture to solve these problems. But the Layer 4 server cluster technique is still not enough for many emerging applications like E-business, because it can’t switch according to the user’s request content. Sometimes it may cause a serious error and reduce the performance of web servers. Content switching is a new technique to come with the tide of fashion, which has the intelligence to make the transmission between clients and servers faster and more reliable. Content switching has three basic approaches, which are URL switching, Cookie switching, and SSL switching. We study these techniques and develop a hardware architecture to implement the Content switching. We use the Content Addressable memory (CAM) and Programmable Logic Device to implement our system to make our solution more programmable. Finally we discuss the policies applying in content switching, and then we estimate the inference and the performance of the system.
Yu, Chung-Wen, and 余忠温. "Development of Regenerative Braking Control System for DC-Excited Flux Switching Machine." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/pmsb68.
Full text國立臺北科技大學
電機工程系
106
Regenerative braking is often employed to extend traveling distance of electric vehicles. This scheme is generally implemented with a bidirectional DC/DC converter in the DC-link to recover braking energy and a battery for energy storage. Thus, considerable increase of hardware and cost is needed. This thesis investigates a regenerative braking control strategy for a DC-excited flux switching machine. The machine was designed to drive small electric scooters. The relationships between recovery energy and motor drive losses are analyzed for the optimal braking conditions. A regenerative braking control strategy is proposed. The system only requires a simple modification to the field driver circuit with the addition of a super capacitor for energy storage. Regenerative braking is realized with the integration of circuit mode switching and control. Experiments are performed to verify the proposed control strategy. The measured losses are generally agreed with the analytic calculations. Moreover, dynamic test results show that the braking energy can be recovered and reused with the proposed strategy. Therefore, total energy used for periodic driving cycles reduced considerably.
Quan, Nguyen Hong, and Nguyen Hong Quan. "Design and Sensorless Control of Three-Phase Wound-Field Flux-Switching Machine." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/xpfw6x.
Full text國立臺北科技大學
電機工程系
107
The research presents a machine design and sensorless control algorithms development for three-phase outer-rotor wound-field flux-switching machines (WFFSM) having field and armature windings on the stator. The outer-rotor configuration is an appropriate candidate for the in-wheel traction applications. On the other hand, the field windings replacing permanent magnets (PM) provide a potential for lower cost applications and the investigation of control algorithms. The operational principle and electro-magnetic design of a three-phase, 12 slot-7 pole (12S-7P) WF-FSM with outer-rotor configuration were studied first. This topology was selected because it produced higher torque and fewer back-electromotive force voltage harmonics than the other topologies. The machine was designed on the basis of the physical dimension limitations for in-wheel traction in a lightweight electric scooter. Because this machine exhibits shaft radial magnetic force caused by the odd rotor poles, a novel dual-structure motor is proposed to reduce this force. The finite element analysis (FEA) calculation results demonstrated that the shaft radial force can be reduced to nearly zero with this design, whereas the generated torque was reduced only by 3%. The effectiveness of the design was also verified through the experiments that compared theii vibrations of the original and the dual-structure motors. The vibration of the dualstructure motor was substantially lower than that of the original motor. The mathematical model for WF-FSM was derived based on the model of permanent magnet synchronous machine (PMSM) with the inclusion of the field component. A 3x3 matrix model has been expressed with both coupling of q-d axes and d axis-field. An approximated high frequency model was also derived for the development of sensorless control. Two sensorless control schemes for WF-FSM are developed in this thesis, the high frequency (HF) voltage injection based and the backEMF based controls. The square-wave HF voltage injection based algorithm has several variations since there are two windings in the machine. Both the analytical and experimental results reveal that the scheme with d-axis voltage injection and q-axis inducing current process is generally similar to that used for PMSMs. Polarity identification is required to prevent phase errors in the estimated position. The schemes with separate windings for voltage injection and current processing demonstrate superior performance compared with the scheme without, and both schemes do not require polarity identification. Moreover, voltage injection at the field winding has an additional advantage for high-speed operations. The second sensorless control scheme developed in this thesis is based on the extended back-EMF. Because of the field excitation, the position estimated from the extended back-EMF has an offset-angle which is related to the field current. The influence of the offset-angle is negligible when the machine is operating in the closedloop control. However, in the start-up period, the offset-angle causes instability to the switching from the open-loop to the closed-loop control. An integrated start-up scheme was also presented which combines the HF voltage injection scheme at standstill, lowspeed and the extended back-EMF scheme at medium, high speeds.
Burgers, K. C. "The non-linear resonant pole soft switching inverter with induction machine load." Thesis, 2014. http://hdl.handle.net/10210/10226.
Full textThe non-linear resonant pole (NLRP) inverter is part of the family of soft switching topologies based on resonant phenomena. The sequence of commutation that occurs between the semiconductors of a conventional voltage source inverter is modified through the mechanisms of energy exchange between added passive energy storage components. The NLRP inverter, through its psuedo resonant behaviour (resonant transition), gives rise to zero voltage and zero current turn-on of the switching devices as well as soft turn-off. The switching device voltage stresses are around 1 p.u, while the current stresses are reduced to around 1.3 p.u, by feeding back a portion of the load current. The rms current flowing through the inductor and switches is greatly reduced by driving the inductor into saturation (non-linear mode of operation). The advantages of soft switching, such as high switching frequency which allows greater dynamic response and higher power densities, along with reduced EMI, are achieved with this topology. Detailed analysis at multi- and sub-cycle levels is carried out, resulting in circuit equations and the criteria for commutation success. The commutation boundaries of the inverter are defined and methods discussed on how to extend them. The modulation of the NLRP inverter and some aspects regarding its use as part of both low and high performance induction motor drives are presented.
Yu, Shin-Yeu, and 游新羽. "A Study on An Isolated Self-excited Induction Machine and Series Connected Self-excited Synchronous Machine Under Switching Conditions." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/3g3gwm.
Full text國立成功大學
電機工程學系碩博士班
90
This thesis investigates the performance of a wound-rotor induction machine under two different operating modes by means of switching conditions. One operating mode is a self-excited induction generator with short-circuited Y-connected rotor terminals while the other is a series connected self-excited synchronous generator with Y-connected rotor windings in series with the stator windings in different phase sequence. The three-phase a-b-c induction-machine model is employed to analyze the performance of the studied machine under two different operating modes. The studied induction machine is also operated as a motor under these two different modes to analyze the startup and loading performance. To validate the proposed mathematical model under different operating modes and loading conditions, the simulated steady-state and transient results are compared with the experimental results obtained from a laboratory 1.1kW wound-rotor induction machine. It can be concluded from the simulated and experimental results that the proposed model is adequate to simulate the performance of the induction machine operated as generator and motor modes under switching conditions.
Jhang, Hong-Hao, and 張鴻豪. "Using Support Vector Committee Machine for Face Tracking Based on Adaptive Color Space Switching." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/43806884727505884968.
Full text國立雲林科技大學
電子與資訊工程研究所
94
In this thesis, we proposed a support vector committee machine (SVCM) based adaptive color space switching for human face tracking. The color space is dynamic switching to the most appropriate color space model (CSM) according to circumstance conditions. Most traditional tracking algorithms used empirical skin color distribution model to discriminate skin/non-skin regions. These empirical skin color models are not considered the illumination and environment variation. It results in less capacity to model skin color distribution. In this thesis, skin color distribution under five color spaces and Laws texture energy are used to represent face features. The features of skin color are used to train support vector machines (SVM) under five CSMs, independently. In the pre-processing, the discrete wavelet transform (DWT) concentrates important features and reduce computational complexity. Then, the face images are transformed into five CSMs and a bootstrap aggregating method is applied to re-sample the training samples for training SVMs. The bootstrap aggregating method promotes the classification accuracy and generalization of learning machine. A specific designed quality measurement is proposed to assess the face tracking performance in five color spaces. Finally, adaptive color space switching aggregates the results of each SVM to select the most appropriate CSM. Experimental results show that the proposed method selects the most appropriate color space automatically. Accordingly, faces could be tracked correctly under varying environment.
Jiang, Jun-Ying, and 江俊瑩. "Design and Control of a 12-Slot 7-Pole DC-Excited Flux Switching Machine." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/6n696h.
Full text國立臺北科技大學
電機工程研究所
104
This thesis investigates the design and control method for DC-Excited flux switching machine. DC-Excited flux switching machine uses dc field windings to replace permanent magnets, so the field is generated by field winding. Because its field can be regulated by dc current, the controllability of this type is more flexible. However, only a few researches have investigated the control strategy. In this thesis, a design and control strategy for three phase 12-slot 7-pole DC-excited flux switching machine is presented. Furthermore, the unbalanced radial magnetic force due to the asymmetric structure is investigated. The mathematical model of this motor is established and compare with the tradition permanent magnet motor, then a control scheme for maximum torque and regenerative braking is discussed.
Chang, Yu-Ying, and 張玉瑩. "The capability of a machine learning expert system to capture the style-switching profitability." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/92503842246809846785.
Full text靜宜大學
企業管理研究所
91
At present, the empirical study of the Efficient Market Hypothesis Theory (1970) was not having the final conclusion. Many studies have shown that there were many factors to influence the return of stocks, and the main factors were Growth and value, Quality, Beta, Yield and Size. But those studies were discussing no more than two dimensions. Therefore, we try to mix five factors to discuss. Beside, we also have taken the change of condition into account, and we join the variation of the condition and five dimensions into the Neuro Fuzzy to predict the rewards. According to the result, we found the anticipation reward by the Neuro Fuzzy was significantly higher than other three strategies. That shown the model of the Neuro Fuzzy has learned the rules between condition and dimension to get the better anticipation result. In addition, in the bull (bear) market analysis, we found that the reward anticipated by Neuro Fuzzy was outperformed the other three strategies in bear market. That was shown the Neuro Fuzzy that join the condition and five dimensions possessing the anticipation ability.