Multiagent Systems is the title of a collection of papers dedicated to surveying specific themes of Multiagent Systems (MAS) and Distributed Artificial Intelligence (DAI). All of them authored by leading researchers of this dynamic multidisciplinary field.

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Multiagent systems: a modern approach to distributed artificial intelligence

Various textbooks have been written on the epidemiology of plant diseases. Most of them present theory of epidemiology, thus giving a description of epidemiological principles. Some of these are of a general nature, whereas others concentrate on specialized subjects, but there are no books on experimental techniques in epidemiology. This omission has been recognized and rectified by Kranz and Rotem. As mentioned in their preface they intended, by editing and publishing the book, 'to help in the development of a methodology able to provide a choice of adequate methods widely acceptable amongst epidemiologists for varying applications and objectives'. For this purpose, they invited 27 distinguished plant pathologists, a number of them from Kranz's 'stable', to participate, and to provide information from their own rich experience. There are 20 chapters spread over four sections. Section I (General techniques), deals with techniques and approaches used in experiments in the field and under controlled conditions. Advantages and disadvantages of such experiments and the relations between them are explained. In Section II (.Measurements and their analysis) disease assessment, crop development and estimation of spore production, dispersal, survival and infectiousness are treated. The analysis of spatial patterns of soil-borne pathogens {s discussed in a separate chapter, for soil-borne diseases have to be approached differently. This section is concluded with two chapters on the monitoring and analysis of environmental factors. Section III (Special topics) is a collection of items, such as the analysis of the effects of control measures, fungicide resistance, virulence in pathogen populations, components in yield loss, development of forecasters, aphid-borne epidemiology, quantitative nematology, geophytopathology and long-distance dispersal. As the editors explain, these are 'not necessarily connected with each other, but all dealing with definite objectives in epidemiological experimentation'. The reasoning for the addition of these topics to the contents is clear. Most are worth treatment, and each has specialized techniques and approaches. The reasoning for collecting them all together under 'Special topics' is a little unsatisfactory. A rather simple rearrangement and naming of the subjects could separate them into a couple of better defined chapters, which would have made the contents more accessible to the eager user. Section IV (The synopsis of experimental restilts) gives the reader a look into the methods in comparative epidemiology, and into the development and use of simulation models for root and foliar diseases. The limitations, necessarily imposed upon the authors, to prevent the publication of an unwieldy and ever more expensive handbook lead to the question whether the editors 'bit more than they could chew'. Especially the chapters on modeling and simulation suffer under these limitations. Most authors have achieved a fine work, though readers, familiar with the authors' publications, can 'taste' a bit of subject.ivity in the choice and approach of techniques and methods by some of them. The book might be a useful addition to the library of all those involved in experimental work in epidemiology, but particularly those called 'novices in epidemiology' in the preface. The editors may have had undergraduates and young postgraduates in mind, but this work might be useful for other epidemiologists too. It is a pity that the high price will hinder young scientists from purchasing the book, particularly those in developing countries.

Book review: Experimental techniques in plant disease epidemiology, J. Kranz & J. Rotem (eds.). Springer-Verlag Berlin, 1989, 299 pp.

A large number of factors such as the increasingly stringent pollutant emission policies, fossil fuel scarcity and their price volatility have increased the interest towards the partial or total electrification of current vehicular technologies. These transition of the vehicle fleet into electric is being carried out progressively. In the last decades, several technological milestones have been achieved, which range from the development of basic components to the current integrated electric drives made of silicon (Si) based power modules. In this context, the automotive industry and political and social agents are forcing the current technology of electric drives to its limits. For example, the U.S Department of Energy’s goals for 2020 include the development of power converter technologies with power densities higher than 14.1 kW/kg and efficiencies greater than 98%. Additionally, target price of power converters has been set below $3.3/kW. Thus, these goals could be only achieved by using advanced semiconductor technologies. Wide-bandgap (WBG) semiconductors, and, most notably, silicon carbide (SiC) based power electronic devices, have been proposed as the most promising alternative to Si devices due to their superior material properties. As the power module is one of the most significant component of the traction power converter, this work focuses on an in-deep review of the state of the art concerning such element, identifying the electrical requirements for the modules and the power conversion topologies that will best suit future drives. Additionally, current WBG technology is reviewed and, after a market analysis, the most suitable power semiconductor devices are highlighted. Finally, this work focuses on practical design aspects of the module, such as the layout of the module and optimum WBG based die parallelization, placement and Direct Bonded Copper (DBC) routing.

Power module electronics in HEV/EV applications: New trends in wide-bandgap semiconductor technologies and design aspects

In recent decades, several factors such as environmental protection, fossil fuel scarcity, climate change and pollution have driven the research and development of a more clean and sustainable transport. In this context, several agencies and associations, such as the European Union H2020, the United States Council for Automotive Research (USCAR) and the United Nations Economic and Social Commission for Asia (UN ESCAP) have defined a set of quantitative and qualitative goals in terms of efficiency, reliability, power losses, power density and economical costs to be met by next generation hybrid and full electric vehicle (HEV/EV) drive systems. As a consequence, the automotive electric drives (which consists of the electric machine, power converter and their cooling systems) of future vehicles have to overcome a number of technological challenges in order to comply with the aforementioned technical objectives. In this context, this paper presents, for each component of the electric drive, a comprehensive review of the state of the art, current technologies, future trends and enabling technologies that will make possible next generation HEV/EVs.

Next generation electric drives for HEV/EV propulsion systems: Technology, trends and challenges

Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) enable higher efficiency, higher power density, and smaller passive components resulting in lighter, smaller and more efficient electrical systems as opposed to conventional Silicon (Si) based devices. This paper investigates the detailed benefits of using GaN devices in transportation electrification applications. The material properties of GaN including the applications of GaN HEMTs at different switch ratings are presented. The challenges currently facing the transportation industry are introduced and possible solutions are presented. A detailed review of the use of GaN in the Electric Vehicle (EV) powertrain is discussed. The implementation of GaN devices in aircraft, ships, rail vehicles and heavy-duty vehicles is briefly covered. Future trends of GaN devices in terms of cost, voltage level, gate driver design, thermal management and packaging are investigated.

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Current Status and Future Trends of GaN HEMTs in Electrified Transportation

This paper presents real time implementation of a digital controlled conventional boost converter works on the fixed frequency driven by the duty cycle control techniques. The digital controller, implemented using ADUC841 microcontroller, monitors the output voltage and calculate the error to determine the next duty cycle value. Simulation and experimental results indicates that the constructed PI controlled boost converter have good transient response as well as stable and accurate steady-state response during the drastically changes occur in input voltage and output load.

http://ieeexplore.ieee.org/iel5/5351135/5354996/05355295.pdf

Real time implementation of a digital controlled boost converter

This paper presents a three-dimensiona (3-D) space vector pulse width modulation (SVPWM) technique via a 4 � 4 orthonormal transformation matrix that has been used as a new approach in controlling a three-phase four-leg voltage source inverter (VSI). A fully optimal digital control scheme for the closed-loop regulation of the three-phase four-leg VSI has been used to synthesize a sinusoidal waveform with the help of the proposed method. Discrete-time modelling of each phase has been obtained independently in abc reference frame, and its optimal controller has been designed using a predened performance index. A DSP-based controlled three-phase four-leg prototype VSI has been designed to verify the proposed discrete time modelling and the control scheme. The simulations and the real-time experiments show that satisfactory results have been obtained for the modelling of the three-phase four-leg VSI in abc reference frame and the 3-D SVPWM technique via 4 � 4 orthonormal transformation matrix at 20 kHz switching

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Optimal digital control of a three-phase four-leg voltage source inverter

Maximum power point trackers are in charge of absorbing the maximum potential power from the photovoltaic panels. Thus, this makes the maximum power point trackers the fundamental parts of the photovoltaic panel systems. The conventional maximum power point tracker algorithms are working well under balanced insolation conditions, however when the partial shade condition occurs, those algorithms are trapped at the local maxima. Hence, under partial shade conditions, the need for a global maximum power point tracking algorithm arises. Particle swarm optimization is a preferential algorithm of maximum power point trackers in literature, especially in partial shade conditions. This paper is focused on improving the existing particle swarm optimization algorithm for maximum power point trackers. The proposed advanced particle swarm optimization algorithm aims to catch the global maximum power point much faster, accurately and to reduce the chatter in the power curve. The proposed method accelerates the global maximum tracking time with gridding the initial search area. The effectiveness of the proposed method is demonstrated with simulation results and these results are compared with a conventional particle swarm optimization method under step changes in irradiance and partial shade conditions of an array of photovoltaic panels.

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An Advanced Particle Swarm Optimization Algorithm for MPPTs in PV Systems

A switched-mode power supply (also called as switching-mode power supply, SMPS, or simply switcher) is an electronic power supply unit (PSU) that incorporates a switching regulator. This paper investigates SMPS design and a filter solution for common mode noises. At first, the design of an SMPS which has three outputs has been presented after that common mode noises have been determined and then these noises have been tried to be reduced by the filter. The experimental studies have shown that there is a considerable reduction in common mode noises thanks to designed filter.

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An application study about SMPS design and reduction of common mode noises

The purpose of this study is to obtain the dynamic model of an electrical powered wheelchair and to estimate the state variables of right and left DC motor currents with the designed observer. First, the dynamic equations are written and then discrete-time state space model of the electrical powered wheelchair is directly obtained from this dynamic equations. Discrete time state space model of the electrical powered wheelchair is verified with the transfer function obtained using the dynamic equations. In addition, the accuracy of the estimated left and right DC motor current values are validated in the simulation results.

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Zekiye Erdem

Papers

Real time implementation of a digital controlled boost converter

Optimal digital control of a three-phase four-leg voltage source inverter

An Advanced Particle Swarm Optimization Algorithm for MPPTs in PV Systems

An application study about SMPS design and reduction of common mode noises

State-Space Modeling of an EPW in Discrete Time and an Observer Design for State Variable Estimation