Power Factor Correction rectifiers are widely adopted as the first stage in most grid-tied power conversion systems. Among all PFC converts for single phase system, Boost PFC is the most popular one due to simplicity of structure and high performance. Although the efficiency of Boost PFC keeps increasing with the evolution of semiconductor technology, the intrinsic feature of high output voltage may result cumbersome system structure with multiple power conversion stages and even diminished system efficiency. This disadvantage is aggravated especially in systems where resonant converters are selected as second stage. Especially for domestic induction cooker application, step-down PFC with wide range output regulation capability would be a reasonable solution, Conventional induction cooker is composed by input filter, diode-bridge rectifier, and full bridge or half bridge series resonant circuit (SRC). High frequency magnetic field is induced through the switching action to heat the pan. The power level is usually controlled through pulse frequency modulation (PFM). In such configuration, first, a bulky input differential filter is required to filter out the high frequency operating current in SRC. Second, as the output power decreases, the operating point of SRC is moved away from the optimum point, which would result large amount circulating energy. Third, when the pan is made of well conducting and non-ferromagnetic material such as aluminum, due to the heating resistance become much smaller and peak output voltage of the switching bridge equals to the peak voltage of the grid, operating the SRC at the series resonant frequency can result excessive current flowing through the switch and the heating coil. Thus for pan with smaller heating resistance, even at maximum power, the operating frequency is pushed further away from the series resonant point, which also results efficiency loss. To address these potential issues, a PFC circuit features continuous conducting input current, high power factor, step-down capability and wide range output regulation would be preferred. The Analysis and design work is present in this article for a non-isolated hard switching DCM SEPIC PFC. Due to DCM operation of SPEIC converter, wide adjustable step-down output voltage, continuous conduction of input current and elimination of reverse recovery loss can be achieved at same time. The thesis begins with circuit operation analysis for both DC-DC and PFC operation. Based on averaged switching model, small signal model and corresponding transfer functions are derived. Especially, the impact from small intermediate capacitor on steady state value are discussed. With the concept of ripple steering, theoretic analysis is applied to SEPIC converter with two coupled inductors. The results indicate if the coupling coefficient is well designed, the equivalent input inductance can be multiple times larger than the self-inductance. Because of this, while maintaining input current ripple same, the two inductors of SEPIC can be implemented with two smaller coupled inductors. Thus both the total volume of inductors and the total number of windings can be reduced, and the power density and efficiency can be improved. Based on magnetic reluctance model, a corresponding winding scheme to control the coupling coefficient between two coupled inductors is analyzed. Also the impact of coupled inductors on the small signal transfer function is discussed. For the voltage follower control scheme of DCM PFC, single loop controller and notch filter design are discussed. With properly designed notch filter or the PR controller in another word, the closed loop bandwidth can be increased; simple PI controller is sufficient to achieve high power factor; THD of the input current can be greatly reduced. Finally, to validate the analysis and design procedure, a 1 kW prototype is built. With 120 Vrms AC input, 60V to 100V output, experimental results demonstrate unity power factor, wide output voltage regulation can be achieved within a single stage, and the 1 kW efficiency is around 93%. / Master of Science

This thesis covers the development of a component specification for the steering system of vehicles engineered by CEVT. This includes the components steering column, intermediate shaft, steering gear and tie rods. Due to the reuse of requirements on the component specification from previous projects it now lacks connection to customer needs. A verification of the component specification is necessary to ensure that no redundant or unnecessary requirements are present. The verification was performed through a comparison between a newly established specification and the current one. Identified customer needs were gathered on complete vehicle level and classified according to customer satisfaction with respect to implementation according to the Kano model. The subjective customer needs were translated into objective, quantifiable metrics on complete vehicle level that was then decomposed onto component level. Customer needs and metrics were then correlated against each other and visualized through the House of Quality matrix. Numeric targets for the metrics were based on its impact on customer satisfaction. This resulted in 50 identified metrics connected to the steering column and 58 metrics connected to the steering gear. The comparison resulted in 22 deviations between the new and current specification where 8 metrics was identified for further investigation. Further development would include investigation of these 8 identified metrics and relate targets to competitors’ performance.

Four wheel steering (4WS) is a concept proven to be beneficial in low speed applications requiring large steering angles, which is the case in city traffic or parking. By steering the rear wheels in the opposite direction to the front ones, maneuverability can be improved. However, a conflict is encountered at high speeds for all the steering strategies developed. If sharper response is achieved, this is at the expense of undesirably large vehicle sideslip angles. On the other hand, small vehicle sideslip angles are associated with heavy understeering behavior. It is not possible to improve both simultaneously in case of two-axle 4WS vehicles. The object of this study is the simulation of various steering configurations for multi-axle vehicles in an attempt to find a means of solving the problem of 4WS and to determine the best steering strategy. In addition to two-axle vehicles which have been extensively studied in literature, three- and four-axle vehicles are taken into consideration. By extending the strategies used for 4WS two-axle vehicles, new strategies are established for three and four-axle vehicles. An integrated non-linear ride and handling model in Matlab &amp / Simulink environment considering sprung and unsprung mass motions, wheel and tire dynamics, is used for simulations. It is shown by case studies that, with the application of the derived strategies for three and fouraxle vehicles, lateral acceleration and yaw velocity responses can be improved without degrading vehicle sideslip angle.

Future heavy duty vehicles will be designed and manufactured with improved Advanced Driver Assistance Systems, ADAS. When developing ADAS, an accurate model of the vehicle dynamics greatly simplifies the development process. One element integral to the vehicle lateral dynamics and development of ADAS is the steering system. This thesis aims to develop an accurate model of a heavy duty vehicle steering system suitable for simulations. The input to the system is an input torque at the steering wheel and the output is the wheel angle. Physical models of the system components are developed using bond graphs and known relations. Some components are modelled with non-linear inefficiencies and friction of different complexity. Unknown parameters and functions are identified from measurement data using system identification tools such as, for example, linear regression and non-linear grid search. The different subsystems are identified separately to the extent deemed possible. Different model designs are considered, validated, and compared. The advantages and disadvantages of different model choices are discussed. Finally, a non-linear state space model is selected for its high accuracy and efficiency. As this final model can be used to simulate a heavy duty vehicle steering system on a desktop computer faster than real time, it fulfills its purpose.

The main aim of this research project is to extend theories of four-wheel-steering as developed by J. Ackermann to include an individually steered four-wheel steering system for passenger vehicles. Ackermann’s theories, including theories available in this subject area, dwell much on vehicle system dynamics developed from what is called single track model and some call it a bicycle model. In the bicycle model, the front two wheels are bundled together. Similarly, the rear wheels are bundled together. The problem with this is that it assumes two front wheels or two rear wheels to be under the same road, vehicle and operating conditions. The reality on the ground and experiments that are conducted are to the contrary. Therefore this study discusses vehicle disturbance rejection through robust decoupling of yaw and lateral motions of the passenger vehicle. A mathematical model was developed and simulated using Matlab R2008b. The model was developed in such a way that conditions can be easily changed and simulated. The model responded well to variations in road and vehicle conditions. Focus was in the ability of the vehicle to reject external disturbances. To generate yaw moment during braking, the brake on the left front wheel was disconnected. This was done because lateral wind generators, as used by Ackermann, were not available. The results from both simulations and experiments show disturbance rejection in the steady state. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

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In this work, we discuss a description of quantum properties of light beams produced by an Optical Parametric Oscillator (OPO) above threshold, pumped by a 780 nm Titanium Sapphire laser, resonant with the D2 line of Rb with a noise spectrum of a coherent beam. The twin beams have wavelengths around 1560nm, in the telecommunication band. The states emitted by the OPO under study are approximately Gaussian (1), which allows us to describe them in terms of first and second order moments. As we analyze the noise spectrum of the fluctuations of each beam, the first order moments are null, which allows us to describe the state of the system in terms of a covariance matrix. We present the behavior of the noise spectrum and the correlations between the reflected pump, signal and idler beams. In addition, we applied different entanglement criteria to study the system. We present a prediction of the bipartite entanglement using Duan criterion (2). For tripartite correlations, we use the Furusawa criterion (3). We performed a study of bipartition pump and sum quadrature. As well, we applied the PPT criterion (4) for continuous variables, independently transposing each beam under study. The PPT criterion is necessary and sufficient to demonstrate entanglement between bipartitions for Gaussian states. In order to explore the behavior of the system using the steering criterion in the model developed by Reid (5), we theoretically study the criterion of inference for bipartite quadratures: between the twin beams or between one of the twin beams and the pump beam. In addition, we analyzed the inference between the three modes, through the bipartition pump mode and combination of sum quadrature of the twin beams. We develop a quantum teleportation protocol of a coherent input state, composed by the Titanium Sapphire beam whose Bell measurement is performed using the pump reflected by the OPO as an entangled state for the signal and idler beams as a first possibility to implement the protocol. Furthermore, we propose a protocol in which the signal beam assists in the process of teleportation. Thus, the fidelity of the system increases and exceeds the limit of non-cloning. We will describe the first measurements of correlations between the beams emitted by the OPO for this system. The tripartite entanglement characterization is the first step in the implementation of quantum optical protocols using a source of entangled states that is compatible with both Rubidium atomic systems and the telecommunications region, thus forming a quantum network. / Nesse trabalho apresentamos uma descrição das propriedades quânticas dos feixes de luz produzidos por um Oscilador Paramétrico Ótico (OPO) acima do limiar, bombeado por um laser de Titânio Safira com comprimento de onda de 780nm, linha D2 do Rb, com espectro de ruído de um feixe coerente. Os feixes gêmeos possuem comprimentos de onda na região de 1560 nm que compreende a janela de transmissão de fibras óticas. Os estados emitidos pelo OPO em estudo são aproximadamente gaussianos (1), o que nos permite descrevê-los em termos de momentos de primeira e segunda ordem. Como analisamos o espectro de ruído das flutuações de cada feixe, os momentos de primeira ordem são nulos, o que nos permite descrever o estado do sistema em termos de uma matriz de covariância. Apresentamos então o comportamento do espectro de ruído e das correlações entre os feixes de bombeio refletido, sinal e complementar. Ademais, aplicamos diferentes critérios de emaranhamento para estudar o sistema. Apresentamos uma previsão do emaranhamento bipartido utilizando o critério de Duan (2). Para as correlações tripartidas, utilizamos o critério de Furusawa (3). Realizamos um estudo da bipartição bombeio e quadratura soma. E, aplicamos o critério PPT para variáveis contínuas (4), transpondo independente cada feixe em estudo. O critério PPT é necessário e suficiente para demonstrar emaranhamento entre bipartições para estados gaussianos. Com o objetivo de explorar qual o comportamento do sistema frente ao critério de \"steering\" no modelo desenvolvido por Reid (5), estudamos teoricamente o critério de inferência para quadraturas bipartidas: entre os feixes gêmeos ou entre um dos feixes gêmeos e o feixe de bombeio. Finalizamos essa análise caracterizando a inferência entre os três modos, através da bipartição modo do bombeio e combinação das quadraturas soma dos feixes gêmeos. Apresentamos a formulação de um protocolo de teletransporte quântico de um estado coerente de entrada formado pelo feixe do Titânio Safira, cuja medida de Bell é realizada utilizando o bombeio refletido pelo OPO como estado emaranhado para os feixes sinal e complementar, como uma primeira possibilidade de implementar o protocolo. Também propomos um protocolo em que o feixe sinal auxilia no processo de teleportação. Dessa forma, a fidelidade do sistema aumenta e supera o limite da não clonagem. Descreveremos as primeiras medidas de correlações entre os feixes emitidos pelo OPO para esse sistema. A caracterização de emaranhamento tripartido nessa nova configuração é o primeiro passo para a implementação de protocolos de ótica quântica utilizando uma fonte de estados emaranhados que é compatível tanto com sistemas atômicos de Rubídio quanto com a região de telecomunicações, formando assim uma rede quântica de transferência e aprisionamento de informação.

The aim of this Master Thesis is to analyze using the system of plans and budgets in a steering of sales department in the company SKODA AUTO a.s. In the theoretical part are basically defined terms plans and budgets and also analyzed different point of views of scientific and professional public on using system of plans and budgets in business management. Then are characterized the basic approaches to budgeting and described in detail the proscedure of establishing the budget. In the practical part is described the analysis of using system of plans and budgets on example of SKODA AUTO a.s. company, during which obtained theoretical knowledge were applied. The analysis revealed a weakness in the steering of sales department and have been proposed the measures, aiming to eliminace this weekness.

In this work, we discuss a description of quantum properties of light beams produced by an Optical Parametric Oscillator (OPO) above threshold, pumped by a 780 nm Titanium Sapphire laser, resonant with the D2 line of Rb with a noise spectrum of a coherent beam. The twin beams have wavelengths around 1560nm, in the telecommunication band. The states emitted by the OPO under study are approximately Gaussian (1), which allows us to describe them in terms of first and second order moments. As we analyze the noise spectrum of the fluctuations of each beam, the first order moments are null, which allows us to describe the state of the system in terms of a covariance matrix. We present the behavior of the noise spectrum and the correlations between the reflected pump, signal and idler beams. In addition, we applied different entanglement criteria to study the system. We present a prediction of the bipartite entanglement using Duan criterion (2). For tripartite correlations, we use the Furusawa criterion (3). We performed a study of bipartition pump and sum quadrature. As well, we applied the PPT criterion (4) for continuous variables, independently transposing each beam under study. The PPT criterion is necessary and sufficient to demonstrate entanglement between bipartitions for Gaussian states. In order to explore the behavior of the system using the steering criterion in the model developed by Reid (5), we theoretically study the criterion of inference for bipartite quadratures: between the twin beams or between one of the twin beams and the pump beam. In addition, we analyzed the inference between the three modes, through the bipartition pump mode and combination of sum quadrature of the twin beams. We develop a quantum teleportation protocol of a coherent input state, composed by the Titanium Sapphire beam whose Bell measurement is performed using the pump reflected by the OPO as an entangled state for the signal and idler beams as a first possibility to implement the protocol. Furthermore, we propose a protocol in which the signal beam assists in the process of teleportation. Thus, the fidelity of the system increases and exceeds the limit of non-cloning. We will describe the first measurements of correlations between the beams emitted by the OPO for this system. The tripartite entanglement characterization is the first step in the implementation of quantum optical protocols using a source of entangled states that is compatible with both Rubidium atomic systems and the telecommunications region, thus forming a quantum network. / Nesse trabalho apresentamos uma descrição das propriedades quânticas dos feixes de luz produzidos por um Oscilador Paramétrico Ótico (OPO) acima do limiar, bombeado por um laser de Titânio Safira com comprimento de onda de 780nm, linha D2 do Rb, com espectro de ruído de um feixe coerente. Os feixes gêmeos possuem comprimentos de onda na região de 1560 nm que compreende a janela de transmissão de fibras óticas. Os estados emitidos pelo OPO em estudo são aproximadamente gaussianos (1), o que nos permite descrevê-los em termos de momentos de primeira e segunda ordem. Como analisamos o espectro de ruído das flutuações de cada feixe, os momentos de primeira ordem são nulos, o que nos permite descrever o estado do sistema em termos de uma matriz de covariância. Apresentamos então o comportamento do espectro de ruído e das correlações entre os feixes de bombeio refletido, sinal e complementar. Ademais, aplicamos diferentes critérios de emaranhamento para estudar o sistema. Apresentamos uma previsão do emaranhamento bipartido utilizando o critério de Duan (2). Para as correlações tripartidas, utilizamos o critério de Furusawa (3). Realizamos um estudo da bipartição bombeio e quadratura soma. E, aplicamos o critério PPT para variáveis contínuas (4), transpondo independente cada feixe em estudo. O critério PPT é necessário e suficiente para demonstrar emaranhamento entre bipartições para estados gaussianos. Com o objetivo de explorar qual o comportamento do sistema frente ao critério de \"steering\" no modelo desenvolvido por Reid (5), estudamos teoricamente o critério de inferência para quadraturas bipartidas: entre os feixes gêmeos ou entre um dos feixes gêmeos e o feixe de bombeio. Finalizamos essa análise caracterizando a inferência entre os três modos, através da bipartição modo do bombeio e combinação das quadraturas soma dos feixes gêmeos. Apresentamos a formulação de um protocolo de teletransporte quântico de um estado coerente de entrada formado pelo feixe do Titânio Safira, cuja medida de Bell é realizada utilizando o bombeio refletido pelo OPO como estado emaranhado para os feixes sinal e complementar, como uma primeira possibilidade de implementar o protocolo. Também propomos um protocolo em que o feixe sinal auxilia no processo de teleportação. Dessa forma, a fidelidade do sistema aumenta e supera o limite da não clonagem. Descreveremos as primeiras medidas de correlações entre os feixes emitidos pelo OPO para esse sistema. A caracterização de emaranhamento tripartido nessa nova configuração é o primeiro passo para a implementação de protocolos de ótica quântica utilizando uma fonte de estados emaranhados que é compatível tanto com sistemas atômicos de Rubídio quanto com a região de telecomunicações, formando assim uma rede quântica de transferência e aprisionamento de informação.

The thesis aim is to visualize and understand what happens to intentions formulated in national steering documents to be interpreted and implemented in schools to give every pupil without exception access to an equivalent education.   The principal starting point is that the individual official, or “street bureaucrat”, working inside school is the key person in interpreting steering document content.  A theory-based analysis model was constructed from the different levels of national school steering systems, including knowledge appropriation and knowledge transfer as theoretical concepts.  In the model, state, municipality, school and pupil constitute separate institutional concepts forming four frames, with three levels, macro, meso and micro, with school and pupil on the latter level. Following the process involving national steering documents, the actual steering of schools and the interpretation and implementation of the mission at different system levels highlights these documents’ importance.   The empirical material comprises five studies: Study 1, a literature study focusing on the expression A school for everyone; Study 2, a document study on the steering of schools in two systems; Studies 3 and 4, two mutually independent questionnaire studies about national steering documents involving school leaders undergoing school leadership education and special needs teachers-to-be during their education and Study 5,  a document study of pupil assistants’ role as officials in the two steering systems.   The conclusion of the thesis may be that the pedagogical significance of the steering documents depends on how administrative and school officials, individually and collectively, interpret and implement the mission among the pupils. Claiming that A school for everyone applies to everyone requires routines in whichever system which ensure that all steering process officials absorb the steering document content and agree on a common pedagogical foundation about who are all pupils, which ones need special support and what measures will give all pupils access to an equivalent education.