Дисертації з теми "Pitch variance"
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Oberhofer, Robert. "Pitch adaptive variable bitrate CELP speech coding." Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264811.
Повний текст джерелаPoole, Sean. "The development of a segmented variable pitch small horizontal axis wind turbine with active pitch control." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020583.
Повний текст джерелаGuentert, Paul H. "A Variable Pitch Quadrotor with Quaternion Based Attitude Controller." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504882010631186.
Повний текст джерелаHarson, Andrew. "A blade angle control system for large variable pitch fans." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334529.
Повний текст джерелаCutler, Mark Johnson. "Design and control of an autonomous variable-pitch quadrotor helicopter." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77106.
Повний текст джерелаCataloged from department-submitted PDF version of thesis. This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 101-106).
The aerospace community, particularly in academia, has seen a recent rise in the popularity of fixed-pitch quadrotor helicopters. The fixed-pitch quadrotor is popular largely because of its mechanical simplicity relative to other hovering aircraft. This simplicity, however, places fundamental limits on the achievable actuator bandwidth and the types of maneuvers possible to fly. This thesis explores the extent to which the addition of variable-pitch propellers to a quadrotor helicopter overcomes these limitations. A detailed analysis of the potential benefits of variable-pitch propellers over fixed-pitch propellers for a quadrotor is presented. This analysis is supported with experimental testing to show that variable-pitch propellers, in addition to allowing for efficient generation of negative thrust, substantially increase the maximum rate of thrust change. A nonlinear, quaternion-based control algorithm is presented for controlling the quadrotor. An accompanying trajectory generation method is detailed with an optimization routine for finding minimum-time paths through waypoints. The control law and trajectory generation algorithms are implemented in simulation and on a custom variable-pitch quadrotor. The quadrotor attitude control is performed on the vehicle using a custom autopilot. Position and attitude measurements are made with an off-board motion capture system. Several flight tests are shown with a particular emphasis on the benefits of a variable-pitch qaudrotor over a standard fixed-pitch quadrotor for performing aggressive and aerobatics maneuvers. To the best of the author's knowledge, this work marks the first documented, autonomous variable-pitch quadrotor built for agile and aggressive flight.
by Mark Johnson Cutler.
S.M.
Pawsey, N. C. K. Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Development and evaluation of passive variable-pitch vertical axis wind turbines." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2002. http://handle.unsw.edu.au/1959.4/18805.
Повний текст джерелаWu, Xiaonan. "Design and Development of Variable Pitch Quadcopter for Long Endurance Flight." Thesis, Oklahoma State University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10813154.
Повний текст джерелаThe variable pitch quadrotor is not a new concept but has been largely ignored in small unmanned aircraft, unlike the fixed pitch quadcopter which is controlled only by changing the RPM of the motors and only has about 30 minutes of total flight time. The variable pitch quadrotor can be controlled either by the change of the motor RPM or rotor blade pitch angle or by the combination of both. This gives the variable pitch quadrotor potential advantages in payload, maneuverability and long endurance flight. This research is focused on the design methodology for a variable pitch quadrotor using a single motor with potential applications for a long endurance flight. This variable pitch quadcopter uses a single power plant to power all four rotors through a power transmission system. All four rotors have the same rpm but vary the blade pitch angle to control its attitude in the air. A proof of concept variable pitch quadcopter is developed for testing the drivetrain mechanism on the vehicle and evaluating performance of the vehicle through numbers of testing.
Wong, Richard Tik Fai. "Sub-micron pitch variable diffraction grating using nanoporous electrodes and electrophoresis of dye ions." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12660.
Повний текст джерелаYalcin, Levent. "Design And Performance Analysis Of A Variable Pitch Axial Flow Fan For Ankara Wind Tunnel." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607091/index.pdf.
Повний текст джерелаHou, Hoe Chen. "Performance of Variable Helix and Pitch Cutting Tools on Chatter Vibration in End Milling of Inconel 718." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/73521.
Повний текст джерелаRosmin, Norzanah. "Internal Model Control (IMC) design for a stall-regulated variable-speed wind turbine system." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16850.
Повний текст джерелаAlshahrani, Ali. "Analysis and Initial Optimization of The Propeller Design for Small, Hybrid-Electric Propeller Aircraft." Thesis, KTH, Flygdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287726.
Повний текст джерелаDenna rapport har som fokus att optimera propellern på ett eldrivet flygplan för att förbättraflygprestationen. Eldrivna flygplan har begränsad energi, i synnerhet motorns vridmomenti jämförelse med bränslemotorns vridmoment. Därav behöver propellern designas om föratt uppnå en större verkningsgrad i propellern. Glauerts teori om flygplanspropellrar haranvänts som metod för designen där vissa modifieringar i teorin har tillämpats enligt Brattför att förbättra teorin. Glauerts teori är en kombination mellan axiell momentum- ochbladelement teori. Specifikationerna för Pipistrel Alpha Electro flygplan har använts sommodell i design metoden. Utnyttjande av propeller med justerbara bladvinklar samt antalblads påverkan har undersökts. De erhållna designresultaten visade att propellern medjusterbara bladvinklar vid planflykt på 3000 m höjd har sparat 0,14 kWh samt ökat propellernsverkningsgrad med 0,4% jämfört med propellern med icke justerbara bladvinklar.Propeller med justerbara stigning var lämplig för elflygplan. Det optimala antalet blad fördesignspecifikationerna är 3 blad.
Feytout, Benjamin. "Commande crone appliquée à l'optimisation de la production d'une éolienne." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2014BOR14946/document.
Повний текст джерелаThe research studies, in collaboration with VALEOL and IMS laboratory, propose several solutions to optimize the production and the efficiency of a wind turbine. The general theme of the work is based on control laws of the system or subsystems using the CRONE robust design. Each part highlights aspects of modeling, system identification and design before simulations or tests of scale and full size models. Chapter 1 provides an overview of the issues discussed in this manuscript, using states of the art and precisions on the industrial and economic context of 2013.Chapter 2 introduces the CRONE command for robust design. It is used to achieve the control of the rotation speed of a variable speed wind turbine, with an innovative architecture - mechanical variable speed solution and synchronous generator.Chapter 3 makes a comparison of three new optimization criteria for CRONE design. The aim is to reduce the methodology complexity and to facilitate handling by any user. The results are obtained through simulations on an academic example, then with a DFIG wind turbine model. Chapter 4 focuses on the reduction of structural loads transmitted by the wind on the turbine. It is about better control of the pitch angle by individual pitch control, depending on the rotor position or wind disturbances.Chapter 5 deals with the design of an anti-icing/de-icing system for blades. After the modeling and identification steps, the CRONE design is used to control the temperature of a heating coating disposed on the blades. An observer is finally designed to detect the presence of ice
MACÊDO, Ana Vitória de Almeida. "Inclusão de energia eólica em sistemas elétricos e controle de frequência utilizando lógica Fuzzy." Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1549.
Повний текст джерелаMade available in DSpace on 2018-08-24T14:29:39Z (GMT). No. of bitstreams: 1 ANA VITÓRIA DE ALMEIDA MACÊDO - TESE (PPgEE) 2017.pdf: 3449345 bytes, checksum: ff78e54595b43261343d5050a8dc3e50 (MD5) Previous issue date: 2017-03-29
CNPq
Um controle para auxílio do controle de frequência é projetado utilizando um método baseado em lógica fuzzy e no controle do ângulo de passo de turbinas eólicas de velocidade variável. O controle visa que as turbinas eólicas operem abaixo do seu valor nominal, estando sempre prontas para aumentar sua geração no caso de evento na rede elétrica, contribuindo para o controle de frequência. Com os esforços para converter tanta energia quanto seja possível com o vento disponível, a potência desperdiçada pela maioria dos controles estudados para elaboração desta tese vale a pena em relação aos benefícios do controle de frequência em sistemas com grande penetração das usinas eólicas, proporcionando a participação da energia eólica nos serviços ancilares. Ressaltando que a introdução de qualquer nova tecnologia de geração no sistema deve ser feita de modo que seja compatível com os princípios operacionais do sistema existente. O controle fuzzy de potência foi desenvolvido no Matlab®/Simulink e permite o bom funcionamento da turbina eólica utilizando uma metodologia alternativa aos controles clássicos. Com isto foi desenvolvido o controle de frequência também baseado em lógica fuzzy. Como grande vantagem do controle fuzzy destaca-se sua fácil adaptação a outros modelos de turbina que utilizem o controle de pitch (turbinas eólicas de velocidade variável), uma vez que o algoritmo é o mesmo, havendo a necessidade apenas de fazer testes para adaptação das faixas de operação do controle.
A control to support the frequency control is designed using a method based on fuzzy logic and pitch angle control in variable speed wind turbines. The control aims that some wind turbines operate below their rated value (derated or deloaded), being always ready to increase their generation in case of some event in the power grid, contributing to the frequency control. With efforts to convert as much energy as possible with the available wind, the power wasted by most controls studied in this work worth of the benefits of frequency control in systems with high power plants penetration, providing wind power to participate on ancillary services. Recalling that the introduction of any new generation technology into the system must be made in a way that is compatible with the operating principles of the existing system. The fuzzy control developed in Matlab®/Simulink for power control enables a suitable operation of the wind turbine using an alternative methodology to the classic controls, it was developed the frequency control also based on fuzzy logic. The fuzzy control great advantage highlight is its easy adaptation to other turbine design which use pitch control (variable speed wind turbines), since the algorithm is the same, just by doing tests for adjustment of the control operation ranges.
Guenoune, Ibrahim. "Commandes non linéaires robustes de systèmes éoliens." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0003/document.
Повний текст джерелаThis work deals the nonlinear control of wind turbine structures. The first objective is the design of control laws of a standard wind turbine with variable speed-variable pitch angle. The proposed control strategies allow controlling the wind turbine indifferent operating areas (optimization and powerlimitation).The second objective consists in controlling a new structure of twin wind turbines. The originality of this structure lies in the fact that it can rotate face the wind without using a dedicated actuator, thanks to the free rotation of the arm carrying the wind turbines. Two control architectures are proposed in order to ensure the structure face the wind : pitch angles differential and the produced power difference. Given that the environment is uncertain (windvariations, modeling errors, noise), robust nonlinear control laws are proposed for a multiple objectives. The efficiency of the control strategies have been carried out according to several scenarios
Qiu, Donghai. "Theoretical and experimental study of tuned nonlinear energy sink : application to passive vibration control." Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0029/document.
Повний текст джерелаThe work presented in this thesis deals with the passive control of dynamics systems subjected to harmonic and transient excitations using a Nonlinear Energy Sink (NES). Several research aspects have been developed: design theory and experimental study of a novel NES, efficient Targeted Energy Transfer (TET) of bistable NES and design criteria for optimally tuned Vibro-Impact (VI) NES. Firstly, a design criterion intended to provide optimal nonlinear stiffness is proposed. Then a novel design of NES system yielding cubic stiffness with conical springs or variable pitch springs and negative stiffness mechanism is developed. Secondly, the experimental procedures for static and dynamic test are presented and applied to validate the concept of NES system. Then a sensitivity analysis is performed with respect to the pre-compressed length of springs. Thirdly, the optimal design of the above device with negative stiffness (termed as bistable NES) is studied. This type of NES is proved to work robustly for different types of excitation, and experimental study of semi-active control are explored. Finally, design criteria for optimally tuned VI NES are studied. Detailed analytical calculations of clearance to control the vibration under different excitations are proposed. A good correspondence between theoretical and experimental results is observed
Djebarri, Sofiane. "Contribution à la modélisation et à la conception optimale de génératrices à aimants permanents pour hydroliennes." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0012/document.
Повний текст джерелаThe improvements of marine current turbines drive train are key features to ensure safe operation and to make tidal energy resource cost-attractive. In this context, eliminating mechanical systems that demand high-level of maintenance can be an interesting way to improve the global behavior of tidal turbines. For that purposes, the presented studies focus on design methodologies and concepts of direct-driven generators associated with fixed-pitch turbines. The proposed designs are based on multiphysics models of the generator that are integrated in an optimization process taking into account the drive train environment. For these reasons, several models have been integrated into a global design strategy in order to find solutions that improve marine current turbines performances. This strategy is based on the use of an optimization process that combines electromagnetic model, thermal model, turbine performances model, and tidal resource velocity profile. This methodology integrates also an efficient control strategy based on a maximum power point tracking (MPPT) approach at low tidal speed and a flux-weakening power limitation control at high tidal speed. This control at high tidal velocities is in this work achieved by considering only the generator electrical control without using blade pitching systems. The obtained results highlight trends that could lead to an improvement of the design and they help designers to set relevant technological choices in order to ensure significant cost reduction and highly improve the reliability of marine current turbines
Şentürk, Sertan. "Computational analysis of audio recordings and music scores for the description and discovery of Ottoman-Turkish Makam music." Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/402102.
Повний текст джерелаEsta tesis aborda varias limitaciones de las metodologías más avanzadas en el campo de recuperación de información musical (MIR por sus siglas en inglés). En particular, propone varios métodos computacionales para el análisis y la descripción automáticas de partituras y grabaciones de audio de música de makam turco-otomana (MMTO). Las principales contribuciones de la tesis son el corpus de música que ha sido creado para el desarrollo de la investigación y la metodología para alineamiento de audio y partitura desarrollada para el análisis del corpus. Además, se presentan varias metodologías nuevas para análisis computacional en el contexto de las tareas comunes de MIR que son relevantes para MMTO. Algunas de estas tareas son, por ejemplo, extracción de la melodía predominante, identificación de la tónica, estimación de tempo, reconocimiento de makam, análisis de afinación, análisis estructural y análisis de progresión melódica. Estas metodologías constituyen las partes de un sistema completo para la exploración de grandes corpus de MMTO llamado Dunya-makam. La tesis comienza presentando el corpus de música de makam turcootomana de CompMusic. El corpus incluye 2200 partituras, más de 6500 grabaciones de audio, y los metadatos correspondientes. Los datos han sido recopilados, anotados y revisados con la ayuda de expertos. Utilizando criterios como compleción, cobertura y calidad, validamos el corpus y mostramos su potencial para investigación. De hecho, nuestro corpus constituye el recurso de mayor tamaño y representatividad disponible para la investigación computacional de MMTO. Varios conjuntos de datos para experimentación han sido igualmente creados a partir del corpus, con el fin de desarrollar y evaluar las metodologías específicas propuestas para las diferentes tareas computacionales abordadas en la tesis. La parte dedicada al análisis de las partituras se centra en el análisis estructural a nivel de sección y de frase. Los márgenes de frase son identificados automáticamente usando uno de los métodos de segmentación existentes más avanzados. Los márgenes de sección son extraídos usando una heurística específica al formato de las partituras. A continuación, se emplea un método de nueva creación basado en análisis gráfico para establecer similitudes a través de estos elementos estructurales en cuanto a melodía y letra, así como para etiquetar relaciones semióticamente. La sección de análisis de audio de la tesis repasa el estado de la cuestión en cuanto a análisis de los aspectos melódicos en grabaciones de MMTO. Se proponen modificaciones de métodos existentes para extracción de melodía predominante para ajustarlas a MMTO. También se presentan mejoras de metodologías tanto para identificación de tónica basadas en distribución de alturas, como para reconocimiento de makam. La metodología para alineación de audio y partitura constituye el grueso de la tesis. Aborda los retos específicos de esta cultura según vienen determinados por las características musicales, las representaciones relacionadas con la teoría musical y la praxis oral de MMTO. Basada en varias técnicas tales como deformaciones dinámicas de tiempo subsecuentes, transformada de Hough y modelos de Markov de longitud variable, la metodología de alineamiento de audio y partitura está diseñada para tratar las diferencias estructurales entre partituras y grabaciones de audio. El método es robusto a la presencia de expresiones melódicas no anotadas, desviaciones de tiempo en las grabaciones, y diferencias de tónica y afinación. La metodología utiliza los resultados del análisis de partitura y audio para enlazar el audio y los datos simbólicos. Además, la metodología de alineación se usa para obtener una descripción informada por partitura de las grabaciones de audio. El análisis de audio informado por partitura no sólo simplifica los pasos para la extracción de características de audio que de otro modo requerirían sofisticados métodos de procesado de audio, sino que también mejora sustancialmente su rendimiento en comparación con los resultados obtenidos por los métodos más avanzados basados únicamente en datos de audio. Las metodologías analíticas presentadas en la tesis son aplicadas al corpus de música de makam turco-otomana de CompMusic e integradas en una aplicación web dedicada al descubrimiento culturalmente específico de música. Algunas de las metodologías ya han sido aplicadas a otras tradiciones musicales, como música indostaní, carnática y griega. Siguiendo las mejores prácticas de investigación en abierto, todos los datos creados, las herramientas de software y los resultados de análisis está disponibles públicamente. Las metodologías, las herramientas y el corpus en sí mismo ofrecen grandes oportunidades para investigaciones futuras en muchos campos tales como recuperación de información musical, musicología computacional y educación musical.
Aquesta tesi adreça diverses deficiències en l’estat actual de les metodologies d’extracció d’informació de música (Music Information Retrieval o MIR). En particular, la tesi proposa diverses estratègies per analitzar i descriure automàticament partitures musicals i enregistraments d’actuacions musicals de música Makam Turca Otomana (OTMM en les seves sigles en anglès). Les contribucions principals de la tesi són els corpus musicals que s’han creat en el context de la tesi per tal de dur a terme la recerca i la metodologia de alineament d’àudio amb la partitura que s’ha desenvolupat per tal d’analitzar els corpus. A més la tesi presenta diverses noves metodologies d’anàlisi computacional d’OTMM per a les tasques més habituals en MIR. Alguns exemples d’aquestes tasques són la extracció de la melodia principal, la identificació del to musical, l’estimació de tempo, el reconeixement de Makam, l’anàlisi de la afinació, l’anàlisi de la estructura musical i l’anàlisi de la progressió melòdica. Aquest seguit de metodologies formen part del sistema Dunya-makam per a la exploració de grans corpus musicals d’OTMM. En primer lloc, la tesi presenta el corpus CompMusic Ottoman- Turkish makam music. Aquest inclou 2200 partitures musicals, més de 6500 enregistraments d’àudio i metadata complementària. Les dades han sigut recopilades i anotades amb ajuda d’experts en aquest repertori musical. El corpus ha estat validat en termes de d’exhaustivitat, cobertura i qualitat i mostrem aquí el seu potencial per a la recerca. De fet, aquest corpus és el la font més gran i representativa de OTMM que pot ser utilitzada per recerca computacional. També s’han desenvolupat diversos subconjunts de dades per al desenvolupament i evaluació de les metodologies específiques proposades per a les diverses tasques computacionals que es presenten en aquest tesi. La secció de la tesi que tracta de l’anàlisi de partitures musicals se centra en l’anàlisi estructural a nivell de secció i de frase musical. Els límits temporals de les frases musicals s’identifiquen automàticament gràcies a un metodologia de segmentació d’última generació. Els límits de les seccions s’extreuen utilitzant un seguit de regles heurístiques determinades pel format de les partitures musicals. Posteriorment s’utilitza un nou mètode basat en anàlisi gràfic per establir semblances entre aquest elements estructurals en termes de melodia i text. També s’utilitza aquest mètode per etiquetar les relacions semiòtiques existents. La següent secció de la tesi tracta sobre anàlisi d’àudio i en particular revisa les tecnologies d’avantguardia d’anàlisi dels aspectes melòdics en OTMM. S’hi proposen adaptacions dels mètodes d’extracció de melodia existents que s’ajusten a OTMM. També s’hi presenten millores en metodologies de reconeixement de makam i en identificació de tònica basats en distribució de to. La metodologia d’alineament d’àudio amb partitura és el nucli de la tesi. Aquesta aborda els reptes culturalment específics imposats per les característiques musicals, les representacions de la teoria musical i la pràctica oral particulars de l’OTMM. Utilitzant diverses tècniques tal i com Dynamic Time Warping, Hough Transform o models de Markov de durada variable, la metodologia d’alineament esta dissenyada per enfrontar les diferències estructurals entre partitures musicals i enregistraments d’àudio. El mètode és robust inclús en presència d’expressions musicals no anotades en la partitura, desviacions de tempo ocorregudes en les actuacions musicals i diferències de tònica i afinació. La metodologia aprofita els resultats de l’anàlisi de la partitura i l’àudio per enllaçar la informació simbòlica amb l’àudio. A més, la tècnica d’alineament s’utilitza per obtenir descripcions de l’àudio fonamentades en la partitura. L’anàlisi de l’àudio fonamentat en la partitura no només simplifica les fases d’extracció de característiques d’àudio que requeririen de mètodes de processament d’àudio sofisticats, sinó que a més millora substancialment els resultats comparat amb altres mètodes d´ultima generació que només depenen de contingut d’àudio. Les metodologies d’anàlisi presentades s’han utilitzat per analitzar el corpus CompMusic Ottoman-Turkish makam music i s’han integrat en una aplicació web destinada al descobriment musical de tradicions culturals específiques. Algunes de les metodologies ja han sigut també aplicades a altres tradicions musicals com la Hindustani, la Carnàtica i la Grega. Seguint els preceptes de la investigació oberta totes les dades creades, eines computacionals i resultats dels anàlisis estan disponibles obertament. Tant les metodologies, les eines i el corpus en si mateix proporcionen àmplies oportunitats per recerques futures en diversos camps de recerca tal i com la musicologia computacional, la extracció d’informació musical i la educació musical. Traducció d’anglès a català per Oriol Romaní Picas.
Chiang, Kei-wei, and 姜愷威. "Improved Pitch-contour Generation Methods Combing ANN, Global Variance and Real-contour Selection." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/73522706160793514552.
Повний текст джерела國立臺灣科技大學
資訊工程系
103
In this thesis, we propose an improved syllable pitch-contour generation method that combines ANN (artificial neural network), global variance and real-contour selection. This method not only alleviates the phenomenon of over-smoothed pitch-contour generated by ANN but also improves the naturalness level of the synthetic pitch contour. In the training stage, the automatically detected pitch contours are checked manually for some types of errors, and then corrected in terms of a program developed here. Next, each syllable pitch contour is transformed into DCT (discrete cosine transform) coefficients. Such DCT coefficients are then used to train ANN model and GV (global variance) parameters, and saved separately according to some context classification modes. In the generation stage, the ANN is used first to predict the DCT coefficients of each syllable pitch-contour according to the inputted contextual information items. Then, the generated DCT coefficients are adjusted by means of GV matching for each DCT vector dimension in order to alleviate the over-smoothing phenomenon mentioned above. Moreover, to promote the naturalness level of the synthetic pitch contours, we base on the DCT vector generated by ANN and adjusted by GV matching to select a real pitch contour from the saved contour pool corresponding to the requested context class. As for the objective assessment of our proposed method, we measure the VRs (variance ratio) under different option setting. It found that the higher VR value will be obtained if the larger weight for GV adjusting is used. In addition, the results of subjective listening tests demonstrate that an appropriate weight value for GV adjusting will improve the naturalness level of the generated pitch contour, and the processing step of real-contour selection will further improve the naturalness level.
Ho, David, and 何大衛. "Fast Code Excited Variant Pitch Gain Vocoders." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/48654614483016623177.
Повний текст джерелаChou, Chia-Cheng, and 周家正. "Study On A Variable Frame Pitch Detection Algorithm." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/ah9mce.
Повний текст джерела中原大學
電機工程研究所
93
ABSTRACT The objective of this thesis is to study the pitch detection methods of speech signals. Pitch is a very important feature in voiced speech and it is widely used in speech applications. Most of the pitch detection methods are based on fixed-length frames. In 1996, Xiaohu Qian and Ramdas Kumaresan proposed a detection method which was based on variable-length frames. According to the author’s research, the proposed method can overcome some weaknesses of other methods based on fixed-length frames, and can get more accurate results. In this thesis, we study the Xiaohu Qian and Ramdas Kumaresan method and try to improve their algorithm. We also study the effects of applying single clipping techniques in the algorithm. In our simulations, we used speech samples from MAT-2000 and compare the results of different algorithms. From the simulation results, we see that the proposed method can further improve the performance.
何晉欽. "Design of variable-pitch-lead-screw type steering mechanisms." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/57679238279911738943.
Повний текст джерелаXiao, Yong-Fa, and 蕭永發. "Variable Pitch Screw of Cutting and on-line Measurement." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/94650530233823317506.
Повний текст джерелаShiau, Jin-Chung, and 蕭金昌. "CNC measurement of variable pitch screw on coordinate measuring machine." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/39924578417333482117.
Повний текст джерелаPawsey, N. C. K. "Development and evaluation of passive variable-pitch vertical axis wind turbines /." 2002. http://www.library.unsw.edu.au/~thesis/adt-NUN/public/adt-NUN20030611.092522/index.html.
Повний текст джерелаYi-TingCheng and 鄭伊庭. "Performance Numerical Simulation of a Wind Turbine with Variable Pitch Blades." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/61043321786734920043.
Повний текст джерелаTsai, Ming Hon, and 蔡明宏. "Dynamic Behavior of Fixed-Speed Variable-Pitch Wind Energy conversion Systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/21187021637562644479.
Повний текст джерела國立高雄應用科技大學
電機工程系
99
This thesis presents the dynamic behavior simulation of fixed-speed variable-pitch wind energy conversion systems in SihMen and SihHu wind farms, operating under normal and abnormal conditions. The components of the system were developed using Simulink together with SimPowerSystems and then employed to cater for the dynamic behavior of the system, including wind turbine model, induction generator model, three-phase power transformer model, capacitor bank model, and static load model. The simulation results show that the system operated acceptably under those conditions and are coincident with practical operations. The dynamic behavior studies of fixed-speed variable-pitch wind energy conversion systems are essential for wind turbine power generation system planning,operation, and further expansion。
Lee, Jeng-Nan, and 李政男. "Studies on the Numerical Control Programming for Variable Pitch Surface Meshing Elements." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/86430060182831359911.
Повний текст джерела國立成功大學
機械工程研究所
83
In this thesis, two kinds of tool path generation methods areachining Variable Pitch Lead Screw with surface meshing elements (V.P.L.S.) on five-axisolled machine. The first method is by generating method employs the cuttere geometry of the cylin- drical roller which drives the envelope surface of V.P. L.S. .l settings is calculated and the tool path generated. A five-axis machine center is usedng of the screw profile. The second method is by combined generating and sculpturing-mill cutter. Through the coordinate transformation,the surface vector operation and theol-axis and tool offset is calculated, this new method combined surface generating withring for the V. P.L.S.surface. The mathematical error in u and v directions between the toolnufacture path has been ana -lyzed and used as a basis for the selection of tool path controlrference check for identifying overcut is also performed by comparing the radius ofe surface to the radius of the tool. Finally, the developed methods are verified with thecomputer graphics and solid cutting software. The NC program is also verified through a trial cutrial. The results showed that the mathematical errors of V.P.L.S. surface can bein tolerance by the proposed methods.
Jin-LunXiao and 蕭敬倫. "Performance Numerical Simulation of a Ducted Water Turbine with Variable Pitch Blades." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/91580916502615625877.
Повний текст джерелаHwu, Ray Hwa, and 胡瑞華. "Scattered-Light Photoelastic Analysis of Contact Stresses of A Variable Pitch Lead Screw." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/27270159550632108683.
Повний текст джерелаCheng, Hong-Yih, and 鄭鴻儀. "On the Conjugate Surfaces of Variable Pitch Lead Screws by Double Enveloping Method." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/43455837126426503783.
Повний текст джерелаChen, Hsin-Hung, and 陳信宏. "On the design of tool profiles for machining line generated variable pitch helicoids." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/22367187145909021800.
Повний текст джерелаLiao, Chi-Min, and 廖啟閔. "Research on Variable Pitch Control of Blades and Hydrostatic Transmission Variable Rotational Speed Control for a 2MW Wind Turbine." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/57812236573001435403.
Повний текст джерела國立臺灣大學
工程科學及海洋工程學研究所
98
The thesis aims to develop a novel pitch control system of a large wind turbine driven by a variable-speed pump-controlled hydraulic servo system. In order to realize practical experiments of the pitch control, the full-scale test rig of the hydraulic pitch control system of a 2 MW wind turbine’s blade, including a novel mechanism of pitch control, a variable-speed pump-controlled hydraulic servo system, a disturbance system and a PC-Based control system, are designed and set up. The variable-speed pump-controlled hydraulic servo system, which contains an AC servo motor, a constant displacement hydraulic piston pump, two differential hydraulic cylinders and hydraulic circuits, performs high response and high energy efficiency, such that it is suitable for the applications in wind turbines. Besides, in order to implement the pitch control in the proposed novel pitch control system, the adaptive fuzzy controller with self-tuning fuzzy sliding-mode compensation (AFC-STFSMC) is developed to design the pitch controller. Finally, the developed variable-speed pump-controlled hydraulic servo system has been realized and verified for the path tracking control of the pitch control of the wind turbines by practical experiments in the full-scale test rig under different path profiles, load torques, and random wind speed. The simulation results of the hydrostatic transmission varable speed control system which is used on 2 MW wind turbines are implemented in this research. Through analyzing of the simulations, the hydrostatic transmission system can replace the gear box and has many advantages used in large wind turbines.
Knag, Yaw-Hong, and 康耀鴻. "On the Curvature of Variable Pitch Lead Screws with Ruled- Revolution-Surface Meshing Elements." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/82409251202334470983.
Повний текст джерела國立成功大學
機械工程研究所
83
Based on curvature theory of differential geometry for spatial curves and surfaces, and curvature theory of conjugate surfaces, this research firstly derives the following curvature equations: principal curvatures, principal directions, normal curvatures along any tangent direction at any point of screw surfaces, induced principal curvatures, induced principal directions, induced radii of curvature, direction of contact line and the geodesic torsion along that direction, lubrication angle, and the condition for avoiding undercutting between the mated surfaces of the screw and the meshing elements. Then, analysis is carried out for various curvatures characteristic of variable pitch lead screws with cylindrical and conical meshing elements, respectively. Furthermore, based on the coordinate transformation and theory of conjugate surfaces, we derive the geometric equations of the variable pitch lead screws with hyperboloidical meshing elements. Then, principal curvatures, principal directions, and geometric characteristics of the hyperboloid of revolution are studied based on differential geometry and curvature theory of ruled surface. And, the curvature characteristic of variable pitch lead screws with hyperboloidical meshing elements are concluded. Finally, the effects on the curvatures of screws for four different motion curves and three angular parameters of the variable pitch lead screws with ruled- revolution surface are compared.
Chang, Wen-I., and 張文壹. "The effect of geometric parameters on the performance of variable pitch lead screw transmission mechanisms." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/73470854742304247987.
Повний текст джерела國立成功大學
機械工程研究所
83
The Variable pitch lead screw transmission mechanism is one of important units in shuttleless weaving looms. It plays a major role regarding the performance of shuttleless weaving looms. A variable pitch lead screw transmission mechanism consists of a slider-crank mechanism, a variable pitch lead screw, and four meshing elements adjacent to both the slider and the screw. The screw is driven by the power flow through the crank, the con- necting rod, the slider, and meshing elements. The purpose of this research is to study the effect of geometric parameters on the kinematic and dynamic performances of variable pitch lead screw transmission mechanisms and to obtain optimum designs. Variable pitch lead screws are generated based on specified meshing elements with special motion curves. Meshing elements of ruled-revolution-surface (cylinder, cone, and hyperboliod of one sheet) and involute-revolution-surface (concave involute- revolution-surface and convex involute- revolution-surface) are adopted. And, the corresponding motion curves are modified trapezoidal curve, modified constact velocity curve, modified sine curve, first type polynomial curve, and second type polynomical curve. A computer program is developed for analyzing kinematic and dynamic performances of designed variable pitch lead screw transmission mechanisms. Five different sets of geometric parameters are inputed into this program to obtaine kinematic and dynamic performances. The results are analyzed, and the effect of geometric parameters are sumarited. In con- clusion, this work provides a powerful tool for selecting geo- metric parameters, meshing elements, and motion curves in designing optimum kinematic and dynamic performances of variable pitch lead screw transmission mechanisms for shuttleless weaving looms.
LIU, JUN-YOU, and 劉俊佑. "On the geometric design of variable pitch lead screw transmission mechanisms with cylindrical meshing elements." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/50866812915001898241.
Повний текст джерелаWu, Feng-Chi, and 吳豐吉. "Geometry Design of Variable Pitch Lead Screw Transmission Mechanisms with Ruled-Revolution-Surface Meshing Elements." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/34921465399162104250.
Повний текст джерелаHsu, Chi-Wei, and 許自瑋. "The Study on the Performance of the Wind Turbine Blades with Variable Pitch Angle Mechanism." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/10490114827228708751.
Повний текст джерела長庚大學
機械工程學系
99
As the rise of environmental consciousness, renewable energy becomes increasingly more prevalent, and wind energy is being used extensively for generation of electricity. Small-sized horizontal-axis wind turbines (SHAWT) offer great advantages in off grid system in rural and remote areas. However, present designs of SHAWT have some defects, such as high startup speed, fixed pitch angle and additional safety device for strong wind, etc. In order to solve these problems, we build wind turbine blades with variable pitch angle mechanism that have high wind speed efficiency, stall control and low startup speed simultaneously. The purpose of this research was to examine the performance of newly developed mechanism. In theoretical analysis, we programmed algorithms based on the Blade Element Momentum (BEM) theory with C programming language to predict the blades performance. And we also development Equation for wind turbine blades with variable pitch angle mechanism, to obtain the relationship between the blades rotational speed, and the pitch-angle variation, v. In experimental design, we establish a car-mounted experimental bench to gain performance data of the blades, which allows us to simulate variable wind conditions by controlling vehicle speed. A magnetic particle brake provides shaft load, and rotational torque sensor used for rotation speed and load measurement. An anemometer is used for wind speed measurement. All the data are recorded in a portable data logger for further analysis. The test result shows that the experimental bench is capable of measuring instantaneous wind speed, rotational speed, and shaft load of the turbine blades. Moving average method was applied to analog data for measure error reduction. The experimental data (Power-) are greatly consistent with the theoretical data, but due to the dynamic stall and the inevitable gust winds, the experiment data has circulatory phenomenon. Furthermore, current design of the safety pin and the pin hole may induce an unsteady turbine performance when Tip Speed Ratio (TSR) > 5. To solve this problem, we illustrate three feasible methods for future research.
Su, Sin-Jhang, and 蘇信彰. "Application of Variable Blade Pitch Control on Improving the Performance of Vertical Axis Wind Turbine." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/986qz5.
Повний текст джерела國立虎尾科技大學
航空與電子科技研究所
100
In viewing that the Vertical Axis Wind Turbines (VAWT) have the advantages over the Horizontal Axis Wind Turbine (HAWT) in insensitive to changing wind directions, low noise and easy installation for buildings in urban and suburban areas, they are being favorably considered for current and future green living environment. On the other hand, the VAWTs are suffered from the inherent problems of no self-start, lower efficiency compared to HAWT, and structural vibration. These problems enlighten that more research efforts are needed, in order to improve the performance of the current commercial VAWT products. This study is intended to improve the performance a VAWT by controlling the pitch angles of the turbine blades while rotating. A single blade wind turbine simulation is performed firstly to investigate the unsteady aerodynamic characteristics and the relation between the tangent force corresponded to rotating angle. The NACA 0015 airfoil is chosen as the section of the rotor blade with chord length 9cm and the radius of the wind turbine is 45cm. The wind speed and tip speed ratio are 7m/s and 2.5. Several fixed and variable pitch angle models are applied to investigate the unsteady flow field of the wind turbine by the methods of computation fluid dynamics. Results show that these blade pitch control models reduced effectively the negative torque regime as well as increase the tangent force of the turbine blade about 8.18% comparing with the without pitch control model. A three blades model is proceeded to study the aerodynamic characteristics of the vertical axis wind turbine. The effects of turbine performance are carried out with varying design parameters including thickness, chord length and camber. Results show that, the average torque coefficient is increased at lower tip speed ratio for the blades of proper thickness. The camber airfoils have the potential to self-start; however, the average torque coefficient shows a reduction in peak efficiencies. The longer the chord length of the blade, the average torque coefficient is reduced. However the average torque is increased. And the point of maximum average torque occurs at lower tip speed ratio. For the pitch control consideration, the models of pitch control are related to tip speed ratio. An appropriate pitch control model can effectively decrease the range of negative torque and the vibration of the wind turbine. The average torque coefficient as well as the energy capture efficiency can be improved. Therefore, the efficiency of the wind turbines in power generation will be enhanced. The efficiency can be raised 243.16% with fixed pitch control. And the efficiency can be enhanced to 486.06% with variable pitch control.
陳健成. "A Study of the Dynamic Cutting Force in Wheel Grinding and Milling with Variable Pitch Cutter." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/07778269160403073195.
Повний текст джерела國立成功大學
機械工程學系
86
This thesis investigate the influence of variablly spaced cutting teeth on milling and wheel grinding force. Based on the tooth sequence function which is composed of geometry of cutting edges, we combined it with elementary cutting function to get milling cutting force for a two tooth face milling cutter. For the purpose of analyzing the grinding geometry, it is convenient to liken the grinding wheel action to that of a milling cutter, with the cutting points corresponding to cutter teeth. We consider the randomness of the cutting edges on the grinding wheel face. Similarty, we model the variable distance between cutting points around the wheel periphery by using Gauss distribution. the dynamic wheel grinding force is derived with elementary cutting function by considering the characteristics of abrasive geometry and its convolution. Finally, milling and dynamic whell grinding forces models are verified with experiments and the results are discussed.
Liu, Tsian-Hsing, and 劉燦興. "The Measurements of Variable pitch screw on 5-Axis machine and three-dimensional coordinate mearsuring machine." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/34212261005482185684.
Повний текст джерела國立成功大學
機械工程研究所
83
This thesis presents an analytical methodology on the NC data eneration for automation measurement of variable pitch lead screw on coordinate measuring machine and mutli-axis machine tools.he desired probe location and the ability functions of 4-axisMM and two multiaxis machine tools are derived by a modified notation. NC data equations are obtained by solving the machine''sink variables through equations of its ability function and theesired probe location matrices.This methodlogy is a general onend is applicable for various mechanical element measuring. Itlso combines the activities of design and quality control, thusaking the production process more flexible, automatic and controllable.
Wu, Chiou-Jin, and 吳秋錦. "On the Geometric Design of Variable Pitch Cylindrical Cam Transmission Mechanisms with Generalized Conical Meshing Elements." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/30190713107638727435.
Повний текст джерелаSheng, Yu-Chun, and 盛玉君. "Studies on the Numerical Control Programming for Machining Variable Pitch Lead Screw on Four-AXIS MACHINE." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/38829237727428045433.
Повний текст джерела國立成功大學
機械工程研究所
81
In this thesis , two kinds of tool path generation methods are developed for machining Variable Pitch Lead Screw with four cylindrical meshing elements (V.P.L.S.) on four-axis numerical control machine . The first method employs end-mill cutter , According to the geometry of V.P.L.S. mechanism , the machine tool settings is calculated and the tool path is generated , A 4-axis machine center with angle head attachment is used for the machining of the screw The second method employs ball-end mill cutter, Through the coordinate transformation , the surface normal vector operation and the tool offset calculation , this new method combined surface generating with surface sculpturing for the V.P.L.S. surface . Finally , an example for N C milling of Variable Pitch Lead Screw with four cylindrical meshing elements is presented . The results show that the mathematical errors of V.P.L.S. surface can be controlled within tolerance by the proposed methods .
Yi-ChengLu and 陸毅誠. "The Guidance and Control of Variable-pitch Quadrotors - Autonomous Landing and Take-off on a Moving Vehicle." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/v7652b.
Повний текст джерела國立成功大學
航空太空工程學系
105
The goal of this dissertation is to construct a system that can use at outdoors and land quadrotors on a narrow (1.2 x 1.2 m) and fast moving (3 m/s) vehicle. In this dissertation, we propose solutions for two key issues related to this research 1. Positioning accuracy improvement We propose a visual positioning system to improve the accuracy of the original positioning system. Unlike most studies that place the system on an unmanned aerial vehicle (UAV), we place the system on a carrier vehicle. The advantage of this architecture is that it significantly reduces the equipment required for the unmanned aerial vehicles, thus it is suitable for UAVs of all sizes. In order to improve the success rate of recognition in cloudy or strong sunlight, we propose Adaptive Background Subtraction and Adaptive Background Threshold algorithms. The image moment of the extracted pattern is then compared to that of the target pattern to confirm the target. Then we calculate the relative position information according to the lens parameters. Benefit from the combination of GPS and inertial measurements is that the system can provide continuous position information when the visual positioning system is temporary unavailable. 2. Quadrotor robustness improvement A variable-pitch quadrotor is proposed to replace the traditional quadrotor as a carrier-based aircraft. Because of its high dynamic bandwidth and more complete control of the output, it is more suitable for operation in harsh environments. However, the variable-pitch quadrotor is completely different from the general quadrotor in the yaw equation; therefore, the traditional control allocation method cannot be applied to the variable-pitch quadrotor. In this paper, we analyze the force and moment equations under various conditions, and derive the control allocation method for the variable-pitch quadrotor. The design of the automatic landing and take-off control system is addressed in this dissertation. Various experiments are conducted to simulate the dynamic motions of the vessel, including up and down motions and moving forward motion. Finally, the quadrotor successfully lands automatically on a moving rover at the speed of 3 m/s in outdoor environment.
Chih-ILin and 林芷誼. "On the Design of Variable Pitch Lead Screw Transmission Mechanism of a Linear Type Blow-Molding Machine." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/11909363969648293080.
Повний текст джерела國立成功大學
機械工程學系碩博士班
98
The linear type blow-molding machine with a variable pitch lead screw consists of a heating system, a linear blow-station, a variable pitch lead screw transmission system, and an infeed-and-outlet system. The va-riable pitch lead screw (VPLS) transmission system consists of a slider, a fixed screw, a rotary screw, and a catch device. It transfers the bottle from the heating system to the blow-station. The design of the motion of VPLS transmission system affects the efficiency of blow-molding machine. This works presents a systematic analytical method to design the motion of VPLS transmission system to improve the performance of blow-molding machine. Firstly, the motion of the VPLS transmission system is analyzed. Based on the design requirements and constraints of the motion of trans-mission system, the curve of VPLS is synthesized by applying the cam motion curves (MT, MS, and MCV). According to Newton’s law and the definition of pressure angle, the pressure angle of the cam mechanisms and the kineotastatic analysis are evaluated. The kinematic and kinetos-tatic characteristics are improved based on the optimal theorem by using the Bezier and Fourier series curves as the design curves. As a result, the motion curve by using the optimum method approach improves the ki-nematic and kinetostatic characteristics of the transmission system of the blow-molding machine and decreases the pressure angle of the VPLS and the input force of the transmission device.
Jong, Shye-Herng, and 鍾協衡. "Studies on the Five-axis Numerical Control Programming for Variable Pitch Lead Screw with Oscillatory Meshing Elements." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/81822127286853579107.
Повний текст джерела國立成功大學
機械工程研究所
82
In this thesis, two kinds of tool path generation methods are developed for machining of Variable Pitch Lead Screw with four oscillatory meshing elements (V.P.L.S.) on five-axis numerical controlled machine. The first one is by generating method with form-mill cutter, according to the geometry of V.P.L.S. mechanism. The machine tool settings is calculated and the tool path is generated. A five-axis machine center is used for the machining of the screw profile. The other method is by combined generating and sculpturing method with end-mill cutter. Through the coordinate transformation, the surface normal vector operation and the tool offset calculation, this new method combined surface generating with surface sc Finally, the developed tool path generationmethods are verified through computer graphic simulation and the trial cut with model material. The advantages of the proposed methods over the sculpturing method are discussed. The results show that the mathematical errors of V.P.L.S. surface can be controlled within tolerance by the proposed methods.
Hsiao, Yun-Fan, and 蕭雲璠. "Novel Design for Variable Pitch Control System and Constant Rotational Speed Control of Rotor for a Small Wind Turbine." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/77462208811205247056.
Повний текст джерела國立臺灣大學
工程科學及海洋工程學研究所
103
Most of the small wind turbines are designed with no control or passive control due to the cost consideration so that the electric generation performance is limited as the wind speed is over the rated wind speed. Thus, the objective of the paper is to improve the electric generation performance by developing a novel active pitch control system and a rotor constant rotational speed control for a 2kW small wind turbine. The study first developed a novel mechanism design for the active-controlled pitch control system. The novel mechanism is the DC servo motor-driving variable-pitch bevel mechanism. By using the PID controller, the one to three bevel gear chain driven by DC servo motor is applied to adjust the pitch angles of the three blades at the same time. Then, the dynamic simulation of the overall system of wind turbine was developed by combining softwares of FAST, ADAMS and MATLAB. After that, the proposed novel mechanism design of the active pitch control and the constant rotational speed control of rotor could be verified via dynamic simulation. For that, the controllers of pitch control and the constant rotor constant rotational speed control were developed by PID control and fuzzy sliding mode control. The experimental prototype system was modified according to the TECO 2kW small wind turbine which original type has no control. The novel mechanism for the active pitch control system and the required controller system were integrated and tested in the open wind tunnel. When the wind speed is above the rated wind speed, the DC servo motor-driving variable-pitch control system starts to work to regulate the pitch angle to keep the constant rotational speed of rotor. The one to three bevel gear chain driven by DC servo motor is applied to adjust the pitch angles of the three blades at the same time. Through the active pitch control system, the constant rotational speed control of rotor can be implemented.
LEE, JUNG-CHIA, and 李榮家. "The Research of the Variable and Constant Practice in the Displaying of Tee ball Accuracy Pitch Skills of the Primary School Students." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/24124738060995708459.
Повний текст джерела國立屏東教育大學
體育學系碩士班
102
This research was according to the extension of schema theories, which based on variability of practice hypothesis. It compared with the constant practice, applying to sports schema of Tee-ball pitch and learning of the pitch skills. It also discussed the influence which were about different practices of tee ball accuracy pitch of primary school students. It adopted the involved model in this research. The fifth grade students of Yili primary school, Pingtung County, took part in this experiment. It divided 60 official participants into different layer clusters, whose ages were 11.38±0.21 years old, the heights were 142.02±5.57 cm, the weights were 41.93±6.03 kg. It represented the analysis of quantity. Before tests, the researcher conducted a 40 minutes class about the accuracy pitch of Tee-ball. Then gave a 7m pre-test to the participants. And according to the results of the pre-test, divided the 60 participants into 5 groups which were the variable practice group, 5m constant group, 6m constant group, 8m constant group and 9m constant group. 4 weeks later, when the researcher gave post-test, retention test and transfer test to the participants, the constant groups pitched 12 times in a fixed distance while the variable groups pitched in the distance of 5m, 6m, 8m and 9m. The participants pitched 3 times in each distance, 12 tims altogether, paused 5 seconds between each pitch. The independent variabilities in this research were based on different groups and tests. The accuracy pitch skills were the dependent variabilities tested in the Mixed design Two-way ANOVA to certify the differences. If the interaction in this way was significant, it would take the simple main-effect tests. The statistic significant level was α=0.5. After discussing the results of the examining , the following were conclusions: A. Represented skill analyse : It had no difference of represented skill in different groups (variable and constant practice) and tests (pre-test and post-test). It had differences in pre-test and post-test. Results of post-test were better than pre-test means that after 4 weeks long practice, accuracy pitch skills were improved. There was a interaction between different groups and tests. The represented skill performances of post-tests both in variable and constant groups were superior than those of pre-tests. It meant that learning effects of the skill acquisition phase were equal in the variable and constant groups. B. Maintained skill analyse: Maintained skill performances did not differ in different groups and tests (pre-test, post-test, retention test). There were significant differences between the pre-test , the post-test and the retention test. Results of post-test and retention test were obviously superior than those of pre-test. Results from high to low were those of post-test, retention test and pre-test. An Interaction existed in maintained skill performances of different groups and tests. Retention test of maintained skill performance in variable group was better than in 9m constant group. After giving each kind of constant groups, results of post-test were better than those of retention test. In 5m and 6m constant groups, results of retention test were better than those of post-test. In variable groups, results of retention test were superior than those of pre-test and post-test. C. Transfer skill analysis: There was no significant difference of transfer skill performances in different groups and different tests (pre-test, post-test, transfer test 1, transfer test 2). significant differences existed in pre-test, post-test, transfer test 1 and transfer test 2 of different tests. Results of post-test were better than those of pre-test and 10m transfer test 2. Results of 4m transfer test 1 were better than those of pre-test, post-test and 10m transfer test 2. Results from high to low were 4m beyond transfer test 1, 7m within post-test and 10m beyond transfer test 2. There was an interaction effect of transfer skill performances between different groups and different tests. For skill performances, those of 4m transfer test 1 of each variable group and constant group were all better than those of pre-test, post-test and 10m transfer test 2. Post-tests of 5m and 6m costant groups were both better than 10m transfer test 2. 10 transfer test 2 of variable group was also better than pre-test.
Αντωνιάδης, Ηλίας. "Μελέτη συμπεριφοράς συστήματος ανεμογεννητριών μεταβλητών στροφών με φορτίο επαγωγική μηχανή και σύνδεση με το δίκτυο". Thesis, 2011. http://hdl.handle.net/10889/4899.
Повний текст джерелаThe first chapter indicates characteristics of wind energy. Studied the wind power, where we see how winds are formed, and we describe the elements of wind and the characteristics of wind performance. Presented finally, briefly, a few introductory information on distributed generation for distributed energy sources. In the second chapter, there is a description of the electric motor systems loads. We study their structure and categorize them according to their torque. In the third chapter we study the three-phase fault and three phase switch. We report the parameters that play a role in short and how it behaves a machine on it. The fourth chapter describes the three-phase transformer. We study the association of these conditions and it is connected. In the fifth chapter we study the variable wind speed control, in Wind Turbines, the power, electronics that we use, frequency inverters and types of generators. We specify the connections and the way we control voltages, active and reactive power through control systems. The sixth chapter is an analysis of the variable wind speed system, where we see Park transformation to convert the axis system, we analyze the model of the machine in another frame of reference (d - q) and apply vector control. In the seventh chapter we design the system with the program MATLAB / Simulink, simulating the system. We analyze the way that we do the initialization of our system in order to simulate in several wind speeds, giving the necessary waveforms.
Κόρκα, Στυλιανή, та Βασιλική Σιμώνη. "Έλεγχος ισχύος και μοντελοποίηση αιολικού συστήματος με ασύγχρονη μηχανή διπλής τροφοδοσίας (DFIG)". Thesis, 2013. http://hdl.handle.net/10889/6717.
Повний текст джерелаThe subject of this thesis is the study and analysis of a variable speed wind turbine equipped with a doubly-fed induction generator (DFIG). At first, an introduction is made of the renewable energy sources, with special mention of the wind energy. Then, there is the description of the different types of wind turbines than exist nowadays, their components and their aerodynamic conversion. A general presentation of a doubly-fed induction generator (DFIG) is made. After that, the dynamic model and the vector control doubly-fed induction generator are presented in order to study various transition phenomena. Finally, the simulation of a wind farm that includes wind turbines of this type, is made and we study the effects of sudden changes of the wind speed.