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European Conference on Antennas and Propagation, EuCAP

作者： Gabor Szladek Janos Bito Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

The percentage of the serviced area of terrestrial BFWA - fed by fiber network or satellite - is investigated for rainy and non-rainy cases. In this paper our results will show that transmitter power can be saved in most of the cases of raining because beside the wanted signal the interference will be higher attenuated by rain shower leading to SINR increasement compared to the non-rainy case. Conventional link budget planning methods ignore the time variance of SINR. Taking into account the phenomena that the wanted and interfering signals are jointly attenuated with the knowledge of temporal and spatial correlation of rain attenuation the link budget planning could be led to using the available transmitter power more environmentally sound applying lower transmit power level.

关键词： Rain Attenuation Signal to noise ratio Interference Power system planning Fluctuations Frequency Gaussian noise Transmitters Radio link

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Utilization of exhaust gas thermal energy – theoretical investigation

Utilization of exhaust gas thermal energy – theoretical inv...

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International Spring Seminar on Electronics technology

作者： Norbert Stuban Adam Torok Department of Electronics Technology Budapest University슠of슠Technology슠and슠Economics Budapest Hungary Department of Transport Economics Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

Even modern internal combustion engines have no more than 40% of efficiency. The remaining 60% of the energy gained from the burning fuel is considered as waste energy. Half of the waste energy is transferred to the environment by the exhaust system. As the exhaust gas has higher temperature than the environment the heat energy of the gas could be utilized. Although this idea is currently being researched by car companies to increase the fuel economy, our purpose with the present research is not to decrease the consumption but to generate electricity from the temperature difference based on the Seebeck effect. The produced electricity can power an emission reducing unit. The theoretical investigation of exhaust gas energetic utilization is described in the paper. The Seebeck efficiency of a 50 W nominal power Peltier element was determined with a measurement series. Based on the lower heating value (LHV) of diesel oil the achievable exhaust energy was calculated. A thermo picture was taken to determine the temperature gradient around the exhaust system on a real car. Finally the necessary Peltier element area was calculated.

关键词： Temperature measurement Resistance Electrical resistance measurement Semiconductor device measurement Waste heat Heat engines

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Hybrid dynamical method of FMS scheduling. a new level of intelligence and automation

Hybrid dynamical method of FMS scheduling. a new level of in...

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IEEE International Conference on Intelligent Engineering Systems (INES)

作者： J. Somlo Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

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Convergence test of model reference parameter adaptive SRM drives

Convergence test of model reference parameter adaptive SRM d...

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European Conference on Power Electronics and Applications

作者： L. Szamel Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

Nowadays switched reluctance motor (SRM) drives have been widely used in the field of controlled electric motor drives. The paper proposes a model reference parameter adaptive control method for SRM drives. The main goal of the drive control is to improve dynamical performance by compensating for the motor nonlinearities. The adaptation practically works only in a relatively narrow speed error track (adaptation range) which is equal to approximately 20-100 revolution/min absolute value of speed error. The drawback of this limitation is the relatively short time for the algorithm to operate. But the convergence of the algorithm is extremely fast which significantly reduces the effect of this drawback. Two more important advantages emerge when adaptation works only with small speed errors. First of all the controller at changing drive parameters adapts to parameters around the value specified by speed reference signal which also assists to speed the adaptation. The other significant positive effect is the disappearing of the problem coming from nonlinear systems that the response of the system can even differ in its character when the value, amplitude of the reference signal is changed. The convergence test of this control method was performed in an experimental drive system. A SRM of 6/8 pole and 4 kW rated power was used. Simulation and experimental results are presented

关键词： Convergence Reluctance motors Reluctance machines Electric motors Adaptive control Control nonlinearities Nonlinear systems System testing Control systems Performance evaluation

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Class-E/sub M/ switching-mode tuned power amplifier-high efficiency with slow-switching transistor

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IEEE Transactions on Microwave Theory and Techniques 2003年第6期51卷 1662-1676页

作者： A. Telegdy B. Molnar N.O. Sokal Ericsson Hungary Limited Budapest Hungary Department of Broadband Infocommunication Systems Budapest University슠of슠Technology슠and슠Economics Budapest Hungary Department of Microwave Department of Microwave Telecommunications Budapest University슠of슠Technology슠and슠Economics Budapest Hungary Design Automation Inc. Lexington MA USA

In class-E switching-mode power amplifiers, the switch-current waveform includes a step change ("jump"), approximated by a ramp of <15% of the period. At a transistor's highest useful frequency, the large input drive required for fast-enough switching yields marginal power gain. Objective: a high-efficiency power amplifier with jumpless current and voltage waveforms. Previously, that was proven impossible for amplifiers using only linear passive components and an ideal switch. We present the theory of a new topology that does achieve the objective: a class-E amplifier with nonlinear passive or active components in the load network. A "biharmonic" version was simulated, built, and tested. It comprises a main stage switching at the output frequency f/sub 1/, drawing DC power of approximately 3/4(P/sub OUT RF//drain efficiency), and an auxiliary amplifier switching at 2f/sub 1/, injecting 2f/sub 1/-current into the circuit node at the main-stage transistor's output port to shape jumpless voltage and current waveforms. That switching (nonlinear) output port converts 2f/sub 1/ power from the auxiliary amplifier to approximately 1/4 of the f/sub 1/ power at the load. Computer simulation, and measurement on a scaled-frequency 3.5-MHz prototype, show that switching losses practically disappear when the main-stage switch is operated in the jumpless regime.

关键词： Switches Power amplifiers Voltage Radiofrequency amplifiers Switching circuits High power amplifiers Network topology Testing Radio frequency Shape

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World-Wide User Identification in Seven Characters with Unique Number Mapping

World-Wide User Identification in Seven Characters with Uniq...

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NETWORKS International Telecommunications Network Strategy and Planning Symposium

作者： Balazs Godor Budapest University슠of슠Technology슠and슠Economics Hungary

There are several initiations to create a unified framework for naming or addressing endpoints in telecommunications networks. UPT, ENUM, UCI are technologies which solve some of the major issues of unified routing but the identifiers they use are based on the E.164 telephone numbers in all cases. This results in different restrictions. This article proposes the unique number mapping as an identification scheme, that could replace the E.164 numbers, could be used both with PSTN and VoIP terminals and makes use of the elements of the ENUM technology and the hexatrigesimal number system

关键词： Routing Internet telephony Electronic mail Next generation networking Web and internet services Europe Space technology Network servers Web server technology management

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Battery characterization for CubeSat missions with battery tester application

Battery characterization for CubeSat missions with battery t...

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International Baltic Electronics Conference, BEC

作者： Gyula Horváth Gábor Marosy Sándor Glisics Dávid Czifra Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

Besides their place in the field of space technology education, the significance of CubeSats is increasing nowadays. Thanks to the miniaturization and to their low cost, technological and scientific experiments can be carried out with such a small satellite. Our paper describes an energy efficient measurement and optimization process which ensures that the onboard batteries are heated up to operation temperature at the beginning of the mission, regardless the initial conditions of its operation.

关键词： Temperature measurement Batteries Battery charge measurement Resistance Electrical resistance measurement Temperature dependence Heating

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Optimal operation of the rotating transformer brushless excitation of synchronous machine

Optimal operation of the rotating transformer brushless exci...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： K. Veszpremi I. Schmidt M. Hunyar Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

The brushless excitation of synchronous machines is an attractive solution for wound rotor machines, since no slip rings are necessary. The paper investigates the rotating transformer method, where the excitation machine is a wound rotor induction machine supplied by an excitation converter. A diode bridge rectifier connected to the three-phase rotor of the excitation machine excites the synchronous machine. The possible power circuits for the excitation converter are presented and the PWM AC chopper is proposed, providing almost sinusoidal supply for the excitation machine. The operation of the system is essentially determined by the commutation of the rotating diode bridge. The different working regions of the diode bridge are considered. The characteristics of the steady-state operation considering the utilization of the excitation machine are introduced, providing a complex design method for the system. A simple and easy feasible method is given for the indirect sensing of the excitation current.

关键词： Synchronous machines Diodes Bridge circuits Wounds Induction machines Rectifiers Pulse width modulation Pulse width modulation converters Choppers Commutation

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Short-term external air temperature prediction for an intelligent greenhouse by mining climatic time series

Short-term external air temperature prediction for an intell...

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IEEE International Symposium on Intelligent Signal Processing

作者： Peter Eredics Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

ISBN: (纸本)9781424450572

Climate control for intelligent greenhouses is currently an active field of research. Model based intelligent greenhouse control systems seem to increase the control performance over traditional solutions. In this paper the control intelligence means the preferably minimal maintenance (heating) cost, within the climatic conditions required to grow sensitive floral cultures. To this purpose it is not enough merely to follow optimally some particular temperature profile. Costs can be minimized if the internal air temperature is predictable within a reasonable time span, and this depends on how well we can predict the dynamics of the external air temperature. The problem is closely related to the prediction of the actual weather conditions within the immediate environment of the greenhouse. The paper demonstrates the limited performance of uninformed, simple methods for temperature forecasts, and introduces more accurate solutions using information from the problem domain.

关键词： Weather forecasting Temperature control Control systems Intelligent control Predictive models Costs Temperature sensors Biological system modeling Economic forecasting Environmental economics

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Application of partial discharge measurement on laboratory aged low voltage cables

Application of partial discharge measurement on laboratory a...

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Electrical Insulation Conference and Electrical Manufacturing & Coil Winding Conference

作者： Z. A. Tamus R. Cselko I. Berta Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

The partial discharge (PD) measurement has been developed for medium and high voltage cables to determine the condition of the insulation. Less attention was paid to diagnostics of low voltage cables, while the low voltage control cables act very important role in safe operation of e.g. power plants. By the results of authors, the partial discharge measurement can be applied for low voltage cables, too. Especially, this method can indicate the degradation effected by thermal stress on PE insulated low voltage control cables. In this article, the result of PD measurement on low voltage cables was examined. By using of statistical methods the general state of cables can be determined more precisely.

关键词： Partial discharge measurement Laboratories Aging Low voltage Partial discharges Cable insulation Voltage control Thermal stresses Medium voltage Power generation

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