Tesis sobre el tema "Reference speed"

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical and Computer Engineering of the Faculdade de Ciências e Tecnologia of Universidade Nova de Lisboa
More and more signal processing is being transferred to the digital domain to profit from the technological enhancement of digital circuits. Where technology scaling enhances the capabilities of digital circuits, it degrades the performance of analog circuits. However, it is important to note that the impact that technology scaling has on digital circuits is becoming smaller and smaller, which means that, in nanotechnologies, to enhance energy and area efficiency, we can not simply depend on the benefits of this scaling. Although, a share of the efficiency can be obtained from the technology, new circuit architectures and techniques have to be developed to really push the limits of efficiency. In data converters, more specifically analog-to-digital converters (ADCs), a decision can be made: research energy and area efficient analog circuit techniques and architectures that cope with technological scaling issues, or design algorithms that use digital circuitry to assist the poor analog technological performance. The former option is the premise for the work developed in this thesis. The work reported in this thesis explores various design techniques with the purpose of enhancing the power and area efficiency of building blocks mainly to be used in multiplying digital-to-analog converter based ADCs. Therefore, novel analog techniques are developed for the three main blocks of an MDAC-based stage, namely, the flash quantizer, the amplifier, and the switched capacitor network of the MDAC. These techniques include self-biasing and inverter-based design for the flash quantizer and amplifier. Regarding the MDAC, it combines three techniques: unity feedback factor, insensitivity to capacitor mismatch, and current-mode reference shifting. In the second part of this work, the designed amplifier is implemented and experimentally characterized demonstrating its practical feasibility and performance. The final part of this work explores the design and implementation of a medium-low resolution high speed pipeline ADC incorporating all the developed circuits. Experimental results validate the feasibility of the techniques and demonstrate the attractiveness in terms of power dissipation and reduced area.

The frequency of a Pulse Width Modulated (PWM) power source can be adjusted to control the speed of an AC machine. Machine response in this mode of operation depends strongly on the quality of the chosen PWM switching strategy. Several methods of PWM waveform synthesis are presented and new methods are introduced. A novel Relaxed Spectrum (RS) algorithm based on a Fourier series expansion of the PWM signal is presented. The algorithm computes sinusoidal and non-sinusoidal switching patterns from a specified set of harmonic coefficients. The RS method is suitable for both full- and half-bridge PWM invertors. Unwanted harmonics inherent in a PWM signal, are exploited to induce excitation into the rotor of a synchronous machine. Rotor mounted diodes are used to rectify the induced currents. 'Rvo novel induced excitation methods are presented which permit accurate control of excitation levels. Whilst the first method uses a single Excitation Harmonic Voltage (EHV) for rotor excitation, an EHV pair is used in the second method to obtain improved machine response. The RS algorithm is applied to obtain a PWM waveform which approximates closest to a given specification. PWM switching patterns are obtained for most possible excitation conditions. Voltage Control Limit Functions (VCLF) are computed which define control limits for several excitation schemes. The response of a computer simulated machine model to an Ideal Test Voltage (lTV) is investigated to assess the performance of the new methods of machine excitation. Simulation reveals that the use of an EHV pair minimises motor torque pulsation. Optimum excitation ratios are then defined in terms of the harmonic indices of a given EHV pair. These ratios are shown to be largely independent of machine parameters. The RS method is used t(] compute generalised sets of PWM switching sequences which can subsequently be applied to a wide range of differently rated machines. Analogue Symmetrical Sample (SS) PWM waveform synthesis methods for induce( excitation are compared with their digital equivalents. It is shown that digital P~ techniques compare favourably and can provide higher excitation levels when a largl fundamental drive voltage is required.

This thesis presents the study and the design analysis of apermanent magnet synchronous motor (PMSM) for the tractionapplication of an electric vehicle. An existing inductiontraction motor for an electric forklift benchmarks the expectedperformances of the proposed PMSM design. Further, thepossibility of using the identical stator as the one used inthe induction motor is explored for the fast prototyping. Theprototype motor is expected to be field-weakened and to have aconstant power speed range (CPSR) of 2.5 to 3.

A design approach based on the CPSR contour plot in aninterior permanent magnet (IPM) parameter plane is derived toobtain the possible designs that meet all the designspecifications and the targeted CPSR. This study provides thepossible alternative designs for the subsequent futureprototype motors.

An analytical approach to estimate the iron loss in PMsynchronous machines is developed and included in the designprocedure. The proposed technique is based on predicting theflux density waveforms in the various regions of the machine.The model can be applied at any specified load condition,including the field-weakening operation region. This model canbe ultimately embedded in the design process for a routine usein loss estimations.

The first prototype motor with an inset permanent magnetrotor has been built and the available measurements are used tovalidate the design performance. In particular, the thermalanalyses based both on the lumped-circuit approach and thenumerical method are compared with the measured results. Asecond and possibly a third prototype motor targeting a widerand higher performance will be carried out in the continuingphase of the project.

Keywords:Constant Power Speed Range, Electric Vehicles,Field-weakening, Reference Flux Linkage, Iron Loss, PermanentMagnet Synchronous Motor, Thermal Analysis

ABSTRACT SENSORLESS DIRECT FIELD ORIENTED CONTROL OF INDUCTION MACHINE BY FLUX AND SPEED ESTIMATORS USING MODEL REFERENCE ADAPTIVE SYSTEM This work focuses on an observer design which will estimate flux-linkage and speed for induction motors in its entire speed control range. The theoretical base of the algorithm is explained in detail and its both open-loop, and closed-loop performance is tested with experiments, measuring only stator current and voltage. Theoretically, the field-oriented control for the induction motor drive can be mainly categorized into two types
indirect and direct field oriented. The field to be oriented may be rotor, stator, or airgap flux-linkage. In the indirect field-oriented control, the slip estimation based on the measured or estimated rotor speed is required in order to compute the synchronous speed. There is no need for the flux estimation in such a system. For the direct field oriented case the synchronous speed is computed with the aid of a flux estimator. In DFO, the synchronous speed is iv computed from the ratio of dq-axes fluxes. With the combination of a flux estimator and an open-loop speed estimator one can observe stator-rotor fluxes, rotor-flux angle and rotor speed. In this study, the direct (rotor) flux oriented control system with flux and-open-loop speed estimators is described and tested in real-time with the Evaluation Module named TMS320LF21407 and the Embedded Target software named Vissim from Visual Solutions Company.

In the first part of this thesis the means are described by which an industrial disc stack centrifuge may be scaled-down to process in a meaningful fashion small volumes of particle suspensions. The centrifuge separation characteristics so measured were suitable for direct scale-up predictions of centrifuge performance. Experiments with a dye tracer and a reduced number of discs indicated that the flow through the disc centrifuge is influenced by the position of the separating discs within the disc stack. This influence was also reflected in the separation performance of a particulate suspension. The results were shown to be in the range obtained using a full-scale industrial disc centrifuge. Experiments also showed a distinct trend that the flow rate and in particular the single passage throughput influenced the separation performance. Using a non-linear curve-fitting algorithm it was shown that the grade efficiency curve of a disc centrifuge may be approximated by a two-parameter model equation. In the second part of this thesis the means are described by which various feed zones designs may be examined in respect to particle breakup using small volumes of a diluted protein precipitate suspension. It has been shown that in the high shear fields which are present in the feed zones to centrifuges the precipitate particles are readily disrupted into smaller fragments, the fragment size depending on the strength of the shear field. Examination of three different feed zone types revealed that particle breakup increased in the following order: full-hermetic < hydro-hermetic < semi-hermetic It has also been demonstrated that the bowl speed and in particular the rotational velocity of the distributor ribs has a significant influence on the level of particle breakup in the hydro-hermetic feed zone, while the effects were less pronounced in the full-hermetic feed zone. Based on the results obtained during the above studies the major mechanism of particle breakup is thought to be due to a combination of turbulence and collision of the particle suspension with the rotating distributor ribs. It has been shown that the level of particle breakup is directly related to the circumferential velocity of the distributor ribs.

Aim: The aim of this study is to analyse potential determinants of cycle commuting speed, with the following research questions: 1. How does cycle commuting speed relate to amount of gears, access to shower facilities, and rating of perceived exertion (RPE), when sex, age, weight, body mass index (BMI), duration, last digit in self-reported duration, and cycling area are controlled for? 2. How are the earlier found relationships between speed and duration, and speed and sex, affected when amount of gears, access to shower facilities, and RPE are added to the control variables age, weight, BMI, last digit in self-reported duration, and cycling area?   Method: In this cross-sectional study, 1526 adult cycle commuters (67% females) in Stockholm County, Sweden, were recruited through advertisements. In a self-administered questionnaire, the respondents reported their sex, age, height, weight, duration of their typical cycle commuting journey, amount of gears, access to shower facilities at the destination, and rating of perceived exertion (measured by the Borg RPE Scale) while cycling. They also drew their cycling route on an individually adjusted map. Multiple linear regression was used to facilitate the analyses.   Results: In a regression model with the independent variables sex, age, weight, body mass index, duration, last digit in self-reported duration (1–4 or 6–9 compared to 0 or 5), cycling area (inner urban compared to suburban and suburban – inner urban), gears, shower facilities, and RPE, the dependent variable cycle commuting speed was positively related to using a bicycle with five or more (as compared to four or fewer) gears, having convenient (as opposed to inconvenient or non-existent) access to shower facilities, and perceiving a higher degree of exertion while cycling. Gears, showers, and RPE were also found to substantially affect the earlier found relationships between speed and duration, and speed and sex. The respondents showed a clear tendency of giving odd-numbered, compared to even-numbered, ratings of perceived exertion.   Conclusions: This study highlights the importance of gears, showers, and RPE in activities such as estimating, planning or taking measures in relation to cycle commuting. It also shows that adding new factors to control for might change earlier established relationships within this field. When the Borg RPE Scale is used, correct instructions strengthens the validity.
Syfte och frågeställningar: Syftet med denna studie är att analysera potentiella påverkansfaktorer gällande cykelpendlingshastighet, med följande frågeställningar: 1. Hur relaterar hastighet till antal växlar, tillgång till duschfaciliteter och skattning av egenupplevd fysisk ansträngningsgrad (RPE), när kön, ålder, vikt, BMI, duration, slutsiffra i självrapporterad duration samt cykelområde kontrolleras? 2. Hur påverkas de tidigare funna förhållandena mellan hastighet och duration, samt hastighet och kön, när antal växlar, tillgång till duschfaciliteter och RPE adderas till kontrollvariablerna ålder, vikt, BMI, slutsiffra i självrapporterad duration, och cykelområde?   Metod: I denna tvärsnittsstudie rekryterades 1526 vuxna cykelpendlare (67% kvinnor) i Stockholms län genom annonser. I ett själv-administrerat formulär rapporterade de kön, ålder, längd, vikt, duration vid deras typiska cykelpendlingsresa, antal växlar, tillgång till duschfaciliteter vid destinationen, och skattning av egenupplevd fysisk ansträngningsgrad (enligt Borgskalan) under cyklingen. De ritade även in sin cykelväg på en individuellt anpassad karta. Multipel linjär regression användes för att möjliggöra analyserna.   Resultat: I en regressionsmodell med de oberoende variablerna kön, ålder, vikt, BMI, duration, slutsiffra i självrapporterad duration (1­–4 eller 6–9 jämfört med 0 eller 5), cykelområde (innerstad i jämförelse med ytterstad samt ytterstad – innerstad), växlar, duschmöjligheter och RPE, var den beroende variabeln cykelhastighet positivt relaterad till användandet av en cykel med fem växlar eller fler (i jämförelse med fyra eller färre), att ha bekväm tillgång till dusch (i motsats till obekväm eller ingen tillgång alls) samt att uppleva en högre grad av fysisk ansträngning under cykling. Växlar, duschmöjligheter och RPE visade sig även substantiellt påverka de tidigare funna förhållandena mellan hastighet och duration, samt hastighet och kön. Respondenterna visade en tydlig tendens att ge ojämna, i jämförelse med jämna, RPE-skattningar.   Slutsats: Denna studie belyser vikten av växlar, duschmöjligheter och egenupplevd ansträngningsgrad vid exempelvis bedömning, planering eller vidtagande av åtgärder i relation till cykelpendling. Den visar även att nya kontrollfaktorer kan förändra tidigare etablerade förhållanden inom detta fält. Korrekta instruktioner stärker validiteten vid användandet av Borgskalan.

A diminuição de habitats tem como consequência a perda de biodiversidade, a mata Atlântica é o Bioma que comporta maior biodiversidade no mundo e devido à ocupação e exploração desordenada ocupa a posição de ecossistema mais ameaçado do planeta, perdendo assim, processos ecológicos, evolutivos, diversidade genética, populações e espécies. Devido a este cenário, a reparação dos danos ambientais gerados tornou-se algo urgente, gerando um campo chamado Ecologia da restauração. Os plantios florestais realizados para restauração das áreas utilizam somente espécies arbóreas, pois se espera que assim seja formada uma estrutura que catalise a sucessão secundária. Porém diversos estudos revelam que mesmo após anos de plantio outras formas de vida não voltam a regenerar com facilidade. O presente trabalho teve como objetivo geral avaliar o comportamento das espécies arbustivas em sua germinação e na recolonização de ambientes em recuperação com diferentes idades, visando auxiliar a utilização de espécies arbustivas em projetos de restauração florestal. Foram utilizadas sementes de 15 espécies arbustivas para avaliação da porcentagem de germinação, velocidade de germinação e Índice de velocidade de germinação, sendo que com Conchocarpus pentandrus (A. St.-Hil.) Kallunki & Pirani foi realizado também teste de armazenamento. Cinco das 15 espécies utilizadas obtiveram boa porcentagem de germinação sem nenhum tratamento prévio de quebra de dormência e Conchocarpus pentandrus obteve melhor taxa de porcentagem de germinação quando armazenado em embalagem permeável por até 3 meses. Para a regeneração natural foram feitas 6 parcelas de 6x8m em áreas com idades de plantio de 4, 7, 12, 15 e 20 anos e mais 6 parcelas em áreas nativas de referência. As áreas estão aumentando sua riqueza e diversidade com o passar do tempo, porém ainda estão longe dos valores atingidos pelas áreas de referência. Poucas arbustivas foram encontradas se regenerando, sendo a maioria arbustos de pequeno porte.
Habitat conversion leads to losses in biodiversity. The Atlantic Forest is that biome that hosts the greatest biodiversity in the world and, due to its unplanned occupation and exploitation, it became the most threatened ecosystem in the planet. It has been losing ecological and evolutionary processes, genetic diversity, ecosystems, populations and species. Because of this scenario, reparation of environmental damage has become vital, which brings up the need for the field of ecological restoration. Forest plantations aiming ecological restoration mostly use only tree species, hoping to achieve a structure that may catalyze secondary succession. However, several studies reveal that even after some years other life forms do not start regenerating easily, mainly in the state of São Paulo where remnant forests are very fragmented. This study aimed to evaluate the behavior of shrub species during germination and recolonization of recovering environments of different ages in order to help better use shrub species in restoration projects. Seeds of 15 shrub species were used to evaluate germination percentage, germination velocity and germination velocity index. Storage test was also performed only for Conchocarpus pentandrus (A. St.-Hil.) Kallunki & Pirani. Five out of 15 species used showed good germination percentage with no previous treatment to overcome dormancy. Conchocarpus pentandrus showed better germination percentage rate when stored in permeable containers for up to 3 months. For natural regeneration, six plots measuring 6x8m were established in plantations of different ages (4, 7, 12, 15 and 20 year-old. Areas are increasing in richness and diversity along the years, but are still far from values of reference sites. A few shrubs were found regenerating and most of them are small shrubs.

Baigiamajame darbe sudarytas uždarosios asinchroninės bejutiklės vektoriškai valdomos pavaros imitacinis modelis ir ištirtos charakteristikos. Teorinėje darbo dalyje yra aptariami asinchroninių elektros pavarų privalumai bei šiose pavarose naudojami greičio jutikliai. Aprašomi stebiklių privalumai bei trūkumai, pagrindžiamas jų naudojimas asinchroninėse pavarose. Nagrinėjami bejutiklių elektros pavarų ypatumai, aprašomi vektorinio valdymo bendrieji principai bei aprašomi bejutiklėse vektoriškai valdomose pavarose naudojamų stebiklių modeliai. Pateikiami du skirtingi asinchroninių variklių matematiniai modeliai. Tiriamojoje dalyje parenkamas asinchroninio variklio modelis, tiriant abiejų imitacinių modelių dinamines greičio charakteristikas. Sudaromas stebiklio imitacinis modelis. Tiriamos stebiklio greičio dinaminės charakteristikos, sudaroma uždaroji greičio reguliavimo sistema su stebikliu. Analizuojamos uždarosios greičio reguliavimo sistemos greičio charakteristikos be apkrovos, su šuoline apkrova ir harmoniškai kintančia apkrova. Nagrinėjama sistemos stiprinimo koeficiento įtaka uždarosios greičio reguliavimo sistemos greičio charakteristikų pereinamiesiams procesams. Magistro darbas baigiamas tyrimo išvadomis, kuriose aptariamas darbo rezultatų realaus pritaikymo galimybės. Darbą sudaro 8 dalys: įvadas, žymėjimai, literatūros šaltinių analizė, tyrimo tikslas ir uždaviniai, teorinė dalis, tiriamoji dalis išvados ir pasiūlymai, literatūros šaltiniai.
The final master degree thesis presents sensorless vector controlled induction motor drive simulation model and characteristics. In the analytic part of master thesis advantages of induction motor drives and speed sensors are described. Advantages and disadvantages of speed estimators are presented and purpose of using them are proved. Peculiarities of sensorless motor drives, principles of vector control and models of speed estimators are analyzed. Two simulation models of induction motor are proposed. In the research part characteristics of induction motors are compared and motor model is chosen. Characteristics of open loop induction motor drive are investigated and simulation model of closed loop induction motor drive with speed estimator is designed. Characteristics of closed loop control system at no load, constant load and harmonic load are analyzed and influence of speed controller gain is considered. Thesis is closed with conclusions about designed system application in real projects. Structure: introduction, list of symbols, literature review, the study aims and objectives, the theoretical part, research part, conclusions and proposals, references.

Avaliou-se o desempenho de um modelo numérico de previsão do tempo (GFS - Global Forecast System – antigo AVN – AViatioN model - do Centro Nacional para Previsão Ambiental – NCEP) no prognóstico de variáveis meteorológicas temperatura, déficit de pressão de vapor do ar, saldo de radiação e velocidade do vento, e da evapotranspiração de referência calculada pelos métodos de Thornthwaite (1948) e de Penman-Monteith (Allen et al., 1998). O desempenho foi avaliado por comparação com dados provenientes de uma estação meteorológica, situada em Piracicaba, São Paulo. A temperatura e o déficit de pressão de vapor do ar foram os elementos melhor prognosticados, com desempenho "muito bom" e "bom", de acordo com o índice de desempenho proposto por Camargo e Sentelhas (1997), para no máximo quatro e três dia de antecedência, respectivamente, durante o período seco. Para o período úmido, somente o prognóstico do déficit de pressão de vapor do ar para o primeiro dia mostrou-se "bom". Os prognósticos de saldo de radiação e velocidade do vento foram ruins para ambos os períodos. Em decorrência do bom desempenho do modelo para prognosticar a temperatura, verificou-se que a estimativa de ETo pelo método de Thornthwaite teve boa concordância com o calculado a partir dos dados da estação meteorológica, com antecedência de até três dias para o período seco. Para o úmido, este fato foi observado apenas para o primeiro dia de antecedência. A concordância entre os valores estimados pelo modelo e a partir da estação para o método de Penman-Monteith foi muito baixa, em conseqüência do desempenho do modelo de previsão do tempo em prognosticar o saldo de radiação e a velocidade do vento.
The performance of a numeric weather forecast model (GFS- Forecast System, former AVN - AvatioN model, National Center for Environmental Prediction-NCEP) was evaluated for predicting weather variables, like air temperature and vapor pressure deficit, net radiation and wind speed, as well as reference evapotranspiration calculated by Thornthwaite (1948) and Penman-Monteith (Allen et al., 1948) methods, by the comparison with data obtained by an automatic weather station, in Piracicaba, State of São Paulo, Brazil. Temperature and vapor pressure deficit were the variables predicted with the best accuracy, with a "very good" and "good" performance, according to the index of confidence proposed by Camargo and Sentelhas (1997), for the maximum of four and three days in advance, respectively, during the dry season. For the wet season, only vapor pressure deficit was predicted with a "good" performance of the model. The predictions of net radiation and wind speed were very poor for both seasons. As the weather forecast model predicted temperature well, ETo estimated by Thornthwaite method showed a good agreement with ETo values estimated by observed data from the weather station, with till three days in advance for the dry season. For the wet season, such agreement was observed just for one day in advance. When ETo estimated by Penman-Monteith method with data from the weather forecast model and from weather station were compared any agreement was observed, which was caused by the poor performance of the numeric weather forecast model to predict net radiation and wind speed.

Les applications entrainées par des moteurs asynchrones consomment à elles seules la majorité de l’énergie électrique utilisée dans le secteur industriel. Des défauts, majoritairement d’origine mécanique, sont susceptibles de se développer au cours du fonctionnement de ces systèmes et rendent nécessaires la mise en place d’une maintenance souvent onéreuse. Afin de réduire ces coûts et d’optimiser la disponibilité des matériels, des méthodes de diagnostic peuvent être développées afin de détecter au plus tôt l’apparition d’un défaut. Cependant, la fiabilité de ces algorithmes et l’automatisation du diagnostic sont complexifiées par la diversité des systèmes alimentés par les variateurs de vitesse industriels ainsi que par le changement de leur point de fonctionnement. Afin de répondre à ces problématiques, un protocole de diagnostic permettant de réaliser une détection sensible et robuste des défaillances mécaniques est développé dans ce travail. Cette méthode consiste à segmenter le plan couple-vitesse du moteur surveillé et à réaliser des références statistiques caractérisant son fonctionnement sain sur chacune des zones de fonctionnement. Des indicateurs de défaut peuvent ensuite être définis statistiquement afin de quantifier l’écart du système vis-à-vis de son comportement sain. Ces indicateurs sont ainsi indépendants du système surveillé et de son point de fonctionnement. Les principales applications ciblées par ce protocole sont les systèmes de compression, de pompage et de ventilation qui représentent une part importante de l’énergie électrique consommée dans le secteur industriel. Le protocole de diagnostic développé dans cette étude est validé expérimentalement dans le cadre de la détection de différentes niveaux de déséquilibre mécanique mais également pour la surveillance d’un système de transmission de type poulies-courroies. De plus, les campagnes expérimentales sont effectuées sur plusieurs systèmes électromécaniques dont les propriétés sont foncièrement différentes afin de valider les performances de normalisation de ce protocole.

Les travaux de recherche développés, dans ce rapport de thèse de Doctorat traitent la commande vectorielle indirecte par orientation du flux statorique d'une machine asynchrone avec ou sans capteur de vitesse. L'approche développée utilise la méthode adaptative avec modèle de référence. Le modèle de référence ainsi que le modèle ajustable, qui sont développés dans un repère lié au stator, sont utilisés pour l'estimation de la vitesse de rotation, de la résistance rotorique et enfin l'estimation mutuelle de la vitesse de rotation et de résistance rotorique d'une machine asynchrone à partir de la connaissance des courants et tensions statoriques. Pour annuler l'erreur statique lors de la régulation de la vitesse et améliorer par la suite les performances des résultats obtenus, le couple résistant, qui peut être considéré comme une perturbation, a été estimé en se basant sur les variables d'état du moteur à commander. Pour cela une procédure d'estimation du couple résistant de la même machine a été développée en se basant sur un observateur de type Luenberger. Les résultats de simulation numérique obtenus dans l'environnement Matlab- Simulink ainsi que les résultats expérimentaux, obtenus sur deux plates formes d'essais de machines asynchrones équipées chacune d'une carte de commande temps réel de type DS1104, valident bien les algorithmes développés
The research developed in this PhD report deal with indirect stator field oriented control (ISFOC) of an induction motor drive (IM), with and without speed sensor. The developed approach uses the method with Model Reference Adaptive System (MRAS). The reference model and the adjustable one, which are developed in stationary stator reference frame, are used to estimate the rotor speed, the rotor resistance and the simultaneous estimation of speed and rotor resistance of the (IM) from the knowledge of the stator currents and voltages. To cancel the static error in the speed control and ameliorate subsequently the performance results, the load torque, which can be considered as a disturbance, has been estimated based on the state variables of the motor to be controlled. For this, a procedure was developed to estimate the torque of the same machine based on a Luenberger observer. The numerical simulations results obtained with Matlab-Simulink software package as well as the experimental results, obtained on two platforms for testing asynchronous machines each equipped with a real time controller board of dSPACE, validate the developed algorithms

Ideal magnetohydrodynamics (MHD) simulations are known to have problems in satisfying the solenoidal constraint (i.e. the divergence of magnetic field should be equal to zero, $

ablacdotvec{B} = 0$). The simulations become unstable unless specific measures have been taken.

In this thesis, a solenoidal constraint satisfying technique that allows discrete satisfaction of the solenoidal constraint up to the machine accuracy is presented and validated with a variety of test cases. Due to its inspiration from Chorin's artificial compressibility method developed for incompressible CFD applications, the technique was named as \
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

This thesis provides a standardized method to measure accuracy for engine and gearbox sensors. Accuracy is defined by ISO 5725, which states that trueness and precision need to be known to provide a metric for accuracy. However, obtaining and processing the data required for this is not straight forward. In this thesis, a method is presented that consists of two main parts: data acquisition and data analysis. The data acquisition part shows how to connect all of the equipment used and how to sample and store all the raw data from the sensors. The data analysis part shows how to process that raw data into statistical data, such as trueness, repeatability and reproducibility for the sensors. Once repeatability and reproducibility are known, the total precision can be determined. Accuracy can then be obtained by using information from trueness and precision. Besides, this thesis shows that measurement error can be separated into error caused by the sensors and error caused by the measurand. This is useful information, because it can be used to assess which type of error is the greatest, whether or not it can be compensated for, and if it is economically viable to compensate for such error.  The results are then shown, where it is possible to gain information about the sensors’ performance from various graphs. Between Hall and inductive sensors, there were no superior winner, since they both have their strengths and weaknesses. The thesis ends by making recommendations on how to compensate for some of the errors, and how to improve upon the method to make it more automatic in the future.

Accurate travel time data are necessary to monitor and evaluate traffic conditions effectively. In the past 20 years, the hours per year lost by the average driver have increased by 300% in the 85 largest U.S. cities, which translates into lost productivity and increased costs. State department of transportation (DOT) agencies and other government organizations need accurate travel time and speed information to better combat this congestion faced by motorists. In the past, ground truth travel time information was typically collected with probe vehicles using the “floating car” method. However, new methods using data collected from global positioning systems by private companies such as INRIX®, Navteq®, and TomTom® have emerged that allow travel time data to be obtained more cheaply and quickly. The Urban Mobility Report (UMR) has turned to these companies, specifically INRIX®, for calculating congestion indices across the United States. This is done by analyzing average speeds and reference speeds supplied by INRIX. The UMR analysis relies on INRIX-supplied reference speeds to calculate delay, which produces artificially high delay on many suburban arterials. Currently, these reference speeds are determined by taking the 85th percentile of weekly speeds (typically overnight hours [10PM to 6AM]). There is a need to refine the reference speeds on arterials in order to account for signal operations, particularly during the daytime hours, so that the UMR more accurately reflects arterial congestion across the nation. Using Bluetooth and INRIX speed data, this thesis develops a new reference speed methodology that accurately reflects arterial delay during daytime hours. This study found that a 60% daytime free-flow reference speed best represents arterial congestion. Using Highway Capacity Manual (HCM) guidelines, this thesis also explores the use of Bluetooth data for arterial and intersection level of service (LOS) analysis under both HCM 2000 and HCM 2010 methodologies. Through analysis, it was found that Bluetooth data capture more of the high and low LOS values compared to the HCM methodology based on segment speed calculations. These high and low LOS values, as well as the rapidly changing LOS between 15-minute intervals, could be attributed to an insufficient sample size.

碩士
中正理工學院
電機工程研究所
86
How to apply vector control technique to induction motor with model reference adaptive system(MRAS) is what we study in this paper. The first, the MRAS estimates rotor flux, electrical angular velocity, and rotor speed, instead of the sensor feedback in the tradition. So, in order to improve estimation accuracy we modify the original design. Next, design the speed controller with MRAS instead of the original PI controller. The MRAS speed controller have no setting parameter problem as PI controller, better speed response in low speed, and better ability with load. Simulation results are obtained by running the Pentium 200 personal computer(PC) with the software MATLAB* SIMULINK*. The experiment is taken by a 3 phase induction motor drive based on PC and an induction motor assembly set. The simulation results of MRAS estimator is not good with speed command 1800rpm of load and no load. However, there are improving speed accuracy after modifying MRAS estimator algorithm. Otherwise, the experiment is good with speed command 180rpm. The simulation results of speed controller designed with MRAS, have no setting parameter problem as PI controller, better speed response in low speed, and better ability with load. The average root mean square error(RMSE) is only 0.0449rpm in speed 1rpm specially. In the experiment results, proceed many kind speed commands to confirm that the MRAS speed controller is superior. So, results of simulation and experiment prove that the paper presents the application of MRAS to estimator and controller having good performance.

碩士
國立臺灣大學
土木工程學研究所
99
To undertake the investment of a HSR project, the most challenging issue is the financing. During the development of the Taiwan High Speed Rail (HSR) project, in the 80s, it was decided to learn from Japan and European countries to build a dedicated HSR line. The government hoped to benefit from the advantages of the HSR and solve the problem faced in the domestic transportation sector. Due to financing difficulties the government made an important decision to build the HSR with private participation (Build-Operate-Transfer). Without previous experiences, the THSR is the first one of the HSR BOT project in the world at the time. The determination to have a successful HSR providing service to the Taiwanese people was the main goal of the government, and despites all the controversies and debates during the project life cycle, it was finally completed and started to provide service in 2007. After the Cold War, America became the world most powerful country economically and politically. In the last two decades the U.S. Federal Government had put its attention in the development of nationwide highway networks and airport systems, neglecting the development of the conventional railway system. Without any HSR line, many serious nature-caused catastrophes and energy crisis had lead to the oil-dependent America reconsider the long-neglected railway system. The development of HSR in America can reduce highway and airway burden, also can cut down country’s carbon dioxide emission and energy consumption. Most importantly, it can reduce the distance and barriers of different States and cities. These issues induced America to reconsider the possibility of HSR, if America decides to build HSR, will eventually turn itself to the biggest HSR market that the world wishes to participate. However the decision toward a HSR line also brings up financial, construction method and environmental issues. Therefore this thesis analyses Taiwan’s private participation experience (BOT) and proposes financial suggestions as reference. Countries interested to develop HSR are numerous, but countries that have enough resources and funding are rare. From Taiwan High Speed Rail experience, this study analyzes the advantages and disadvantages of a HSR project using BOT model. From the point of view of the government, advantages are to reduce financial burden, introduce private sector efficiency, and minimize the risk of construction and operation. However, disadvantages are time spending in the contract negotiation and the design of related laws. By expert interviews and survey analysis, this study points out key issues when implementing alternative financing in HSR: Implementation of project financing, basic acts to promote HSR, procedures and involvement, contract terms and bidding control procedures, ridership expectation, etc. This study aims to reduce risk and cost for countries seeking for alternative financing to execute their high-speed rail project.

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the Degree of Doctor of Philosophy.
Variable speed motors are achieved by varying the voltage of a DC machine or by varying the frequency of an AC machine, the former method being the simpler of the two. DC motors have the major disadvantage of brushes and commutators which require regular downtime for maintenance, a fact already recognised by Tesla [1] in 1888. Thus the AC motor, in particular the induction motor, is of a more rugged design and does not suffer from the commutator problem of its DC counterpart. Recent advances in the technology of the power electronics used to supply a variable frequency to the motor has allowed the induction motor to be a viable alternative to the DC motor in variable speed applications. Problems have been encountered in industry when an inverter is injudiciously selected to be combined with a motor. Such problems were highlighted by difficulties being experienced with some 400 kW inverter drives. The inverters had been bought from one supplier and the motors from another. When this system was coupled together, there was excessive heating in the motors and the overall plant was only able to operate well below its capacity, incurring a substantial weekly loss of income. The motor and inverter were evidently incompatible, and since the inverter could not be modified, the motor was redesigned to make it less susceptible to the harmonics present in the inverter waveform, These problems have led to the development of a variable speed drive simulation package at the University for use by the local industry which can accurately model the complete system of inverter, motor and its associated load. It is envisaged that this package could be used to predict the performance of a drive system and highlight problems that may occur. To be able to do this, an accurate model of the motor is required. This investigation gives the development of an induction motor model which is suitable . for variable speed drive system simulations. The model accounts for the deep bar effect by using lumped parameter circuits and includes saturation of the leakage paths using only information which is typically available from motor design data. A complete analysis is given of the different lumped parameter models and their suitability for use in this application. The thesis also shows the utilisation of the deep bar model to simulate reswitching transients and double cage motors. The author hopes that the models used in the simulation package wallow industry to predict problems prior to their occurrence, alter the designs and thereby avoid costly remanufacture of the system.
Andrew Chakane 2018

碩士
國立高雄第一科技大學
營建工程所
92
BOT (Build-Operate-Transfer) is a construction model involving private enterprises participating in public projects. Due to scarcity and difficulties in procuring sufficient fund by the government, many of the major public projects are given out in a form of BOT construction, i.e. construction and funding are done by the private enterprises, in return the private enterprises are given the operation revenue for an agreed period. Under the BOT concept, the concessionaire (the private enterprise given the concession for the project) will normally sub-let out the construction portion to main contractors in the form of turnkey construction. In Taiwan, this concept is still at the infant stage and many contractors are not familiar with the concept. This BOT case study will concentrate on problems encountered for BOT project involving turnkey construction with self quality control. Some references are made on overseas experience with similar construction procurement background. Particular case study is made on the Taiwan High Speed Rail and Kaohsiung Mass Transit BOT project. This detailed study includes information collected during construction period, interviews with the relevant staff, which includes the concessionaire, the contractors and the construction professionals. From there, gained an in depth understanding of the quality control model, the operation mechanism and the associated problems. Subsequently, finding the root causes of the problems and developing suitable solutions. These can be helpful and will set an example for the smooth implementation of future BOT project involving turnkey construction and self quality control in Taiwan. The difference and the respective advantage and disadvantage of the QA/QC systems adopted by THSRC and Kaohsiung MRT project 1.Contractor’s responsibility — The contractor for THSRC contractor is solely responsible for the QA/QC of work in accordance with a standard required by the contract. This is a fundamental feature of a BOT contract. On the other hand, for the KMRT project, the main responsibility for QA/QC is in the hands of an appointed QA/QC company rather than the Contractor for the project. This setup maybe considered a disadvantage to the project and work progress due to the fact that the contractor is not solely in control of everything. 2.The appointed QA/QC Company — The responsibility of THSRC as the Employer Representative of the project is to monitor and carry out regular audit to ensure the requirements are met and properly maintained by the contractor. The contractor still remains solely responsible and is not required to refer to a third party. The responsibility of KMRT as the Employer Representative of the project is responsible for the QA/QC of work, the hold point should be checked by Employer Representative. 3.Independent QA/QC checking — For KMRT project the QA/QC company is selected through the traditional government tendering process. The selection method naturally carries with it the traditional bureaucratic procedure in the running of the project and is an additional burden the project management has to carry. 4.IV & V — The advantage to the KMRT project in appointing own QA/QC Company is that the Government has greater and direct control over the quality of work but may involve greater expenditure. 5.Government Audit — The advantage of THSRC project in carrying out audit is mainly a process, which requires the contractor to provide documentary evidence of all the QA/QC work. The provision of such evidence however does not relief the contractor the overall responsibility of the quality of work. On the other hand for the KMRT project, because the Government used the traditional selection process, the project control and audit required are also bound by the terms and conditions set forth in the traditional form of contract. 6.Conceptual design review — The advantage of KMRT project by independent checking in this respect is that the appointed company can ensure compliance but the disadvantage is that there is more work involved. 7. Detail design review — a) In KMRT project, the contractor is required to submit the design to the Government for reference b) To authrize the consultant to do the check by Employer Representative has less party involved in carrying the review process and therefore incurs lesser expenditure. c) The KMRT project requires only normal design review effort. In comparison THSRC requires full design review, which is better in checking that the design has less mistake but cost of performing the review is higher. 8.Contractor independent review — The advantage of THSRC is that the design review responsibility is more flexible in implementing. The contactor can choose to carry out work before approval is given on their own risk. The contractor for the KMRT project can only permit to commence work upon approval from C3 consultant. The contract has no provision for the contractor to take risk in this manner. From the above the QA/QC procedure for both projects has their own advantage and disadvantage. The main advantage of THSRC project to the Employer (which is the Government) is that the project is privatized and there is financial burden incurred to the Government. On the other hand for the KMRT project the Employer is comprehensively involved and the project implementation is through the traditional tendering procedure. From the contractor’s point of view, the KMRT contractor does not have sole responsibility in QAQC of the work, which is a very important feature pivotal to the success of a project. At best they can be considered a project awarded by a traditional form of contract with an additional responsibility in design. In accordance with the result of above research and analysis, I recommend the following; 1.In the course of our visits, we found the majority of staff who have knowledge of BOT contract prefer to use THSRC contract as a model to carry out their work. This is to enable them to carry out own QAQC work; reduce many inherent shortcomings associated with traditional type of contract. But on the other hand, the appointed Consultant and their staff still tend to carry out supervisory work and carry with them a sense of responsibility that conform to the traditional role of work supervision (to name an example, Kaoshiung MRT project ). This show that many in Taiwan still distrust a company taking over total management and control of work. I suggest to carry out further research into this subject matter. 2.The model adopted by THSRC is imported from abroad. This model has been in use for many years oversea. It is considered the first time it has been adopted in Taiwan. Is it successful? Up to this day of implementation, it is considered half-success and half-failure. From the work completed thus far, the question can be asked; for the same system of QAQC adopted for various contract, why there exist a large disparity in the quality of work achieved? It is suggested therefore to carry out further study to this question. 3.From the questions arisen as a result of this research, the cause of the problem shall be the subject of further study. 4.This study on both THSRC and Koashiung MRT form of contract, comparison of the management of work quality method, is a good reference for future adaptation of future BOT type of contract. 5.It is expected that the work quality achieved from BOT and turnkey type of contract as compared to those achieved from the Government awarded type of contract has considerable difference. It is suggested further research can be carried out to look into this subject matter.

Цель работы – разработка новых технических средств повышения точности и быстродействия приводов подач металлорежущих станков при высокоскоростном точении. Проведен анализ погрешностей собственно привода и системы отсчета перемещений, анализ существующих способов борьбы с погрешностями. На его основе разработаны следящий привод подачи металлорежущего станка, система отсчета перемещений рабочего органа машины, методика настройки системы отсчета перемещений рабочего органа станка и алгоритм настройки компенсирующей цепи системы отсчета перемещений с использованием ПК. Данные средства точнее существующих. В ходе работы над магистерской диссертацией, было получено 2 патента (№160849 Следящий привод подачи металлорежущего станка и №154592 Система отсчета перемещений рабочего органа машины). Участие во Всероссийской молодежной научно-практической конференции «Региональные программы и проекты в области интеллектуальной собственности глазами молодежи». Тезис доклада опубликован в сборнике трудов конференции.
The purpose of the work is the development of new technical ways to improve the accuracy and operation speed of feed drive of machine tools in high-speed turning. The analysis of accuracy of feed drive and reference frame of driven element displacement, existing ways of errors elimination was carried out. The analysis was used in order to design follower feed drive feed of machine tool, reference frame of driven element displacement of the machine tool, tuning method of reference frame of driven element displacement of the machine tool and tuning algorithm of bucking circuit of reference frame of driven element displacement with using a PC. Developed solutions give more accurate results. During the work on the master's thesis author received 2 patents of RF (№160849 Follower drive feed of machine tool and Reference frame of driven element displacement of the machines). The work participated in the All-Russian youth scientific conference "Regional programs and projects in the field of intellectual property through the eyes of young people". Abstracts of the report are published in the conference digest.