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Electrotechnical Conference, 1989. Proceedings. 'Integrating Research, Industry and Education in Energy and Communication Engineering', MELECON '89., Mediterranean

Date 11-13 April 1989

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Displaying Results 1 - 25 of 197
  • Discontinuous conduction mode in the SEPIC converter

    Publication Year: 1989, Page(s):38 - 42
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (266 KB)

    The steady-state and dynamic analysis of the SEPIC converter in the discontinuous conduction mode by means of averaging techniques is considered. As a result, similar behavior to that of the Cuk converter was found. It is noted that the results obtained can be used for the optimum design of switching regulators using a SEPIC converter as a power stage.<> View full abstract»

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  • MELECON '89: Mediterranean Electrotechnical Conference Proceedings. Integrating Research, Industry and Education in Energy and Communication Engineering (Cat. No.89CH2679-9)

    Publication Year: 1989
    Request permission for commercial reuse | PDF file iconPDF (54 KB)
    Freely Available from IEEE
  • Short term reliability and cost of operation for an autonomous energy system

    Publication Year: 1989, Page(s):107 - 110
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    The authors describe an algorithm for determining the reliability and cost of operation of an autonomous energy system consisting of diesel units and wind generators over a period of T hours. The simulation period is divided into intervals of t minutes duration. Given the characteristics of the diesel and wind generators, the hourly loads, and the statistics of wind velocity, the... View full abstract»

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  • Performance of direct sequence spread spectrum systems using continuous phase modulation

    Publication Year: 1989, Page(s):520 - 523
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    The author analyzes and compares different continuous phase modulation (CPM) schemes in direct-sequence (DS) spread-spectrum systems under the assumption that the out-of-band power is limited. It is shown that a processing gain improvement can be achieved using CPM with respect to the DS system with binary phase-shift keying when both systems operate within the same bandwidth. The exact expression... View full abstract»

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  • Repercussions from the connection of wind turbines to the local grid

    Publication Year: 1989, Page(s):104 - 106
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (188 KB)

    Repercussions of the connection of dispersed wind turbines to the steady-state operation of the local grid are examined. An interactive computer program is used which provides the voltage fluctuations and the line losses at selected points of a typical 20 kV rural distribution feeder with and without wind turbines. The results presented indicate that utilities will not face serious voltage regulat... View full abstract»

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  • A direct-sequence spread-spectrum public portable telephone

    Publication Year: 1989, Page(s):516 - 519
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    Attention is given to a portable telephone system using direct-sequence spread-spectrum multiple-access and binary phase-shift keying (BPSK) with coherent demodulation. The system has several pairs of base-portable units for each user. Instead of being concentrated in a central point, the base stations are distributed in an area. Each base station, then, serves as the central point of a covering a... View full abstract»

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  • Adaptive control of an asynchronous aeolic generator using the field-oriented technique

    Publication Year: 1989, Page(s):99 - 103
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    The wind power generation process using asynchronous generators is analyzed. The study includes modeling and simulation of the windmill and the asynchronous generator, using for the latter the dynamic field-oriented model. The need to keep the power generated within admissible limits imposes the realization of a control over the pitch blade of the windmill so that the effective mechanical power su... View full abstract»

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  • Fast PN sequence correlation by using FWT

    Publication Year: 1989, Page(s):513 - 515
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (184 KB)

    A simple relation between Walsh functions and PN (pseudonoise) sequences is derived. It is shown that by using a suitable permutation a set of discrete Walsh functions-sequences can be transformed into the set of different phase shifts of a single PN sequence. A matched filter-correlator based on the fast Walsh transform (FWT) which exploits this property is proposed. This correlator can be effici... View full abstract»

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  • A flexible control strategy to interface solar system with privileged load and utility line

    Publication Year: 1989, Page(s):25 - 30
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (292 KB)

    An intermediate photovoltaic power system (160 kVA, 380 V three-phase) that could be used as a stand-alone energy power supply and as an AC back up system has been designed. For this purpose it was necessary to use self-commuted inverters; a suitable power control logic was also required in order to compensate for reactive power and optimize power flow from the photovoltaic array to the AC power l... View full abstract»

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  • Conjugate gradient equalizers adaptation algorithm versus LMS algorithm

    Publication Year: 1989, Page(s):201 - 204
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    The LMS (least mean square) and conjugate-gradient window (CGW) algorithms are considered for use in digital equalizers. The equalizer with implementation of the CGW algorithm is shown to require more computation, but the convergence is faster and the equalizer can be used in worse conditions. The simulation results are encouraging. The implementation of the CGW method for multilevel quadrature mo... View full abstract»

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  • Control system for a wind turbine driven self excited asynchronous generator

    Publication Year: 1989, Page(s):95 - 98
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    The authors present a method for the analysis of the operation of a self-excited induction generator which also provides a procedure for the computation of the required external control capacitance and resistance. A number of switchable control capacitors and resistors can be used to provide variation in discrete steps in order to balance active and reactive power. The objective is to develop a dy... View full abstract»

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  • Performance of 16 and 64 QAM digital radio systems with multipath propagation and distortion induced phase jitter

    Publication Year: 1989, Page(s):509 - 512
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (212 KB)

    The authors present a novel method for assessing the bit error probability in a QAM (quadrature amplitude modulation) system, taking into account thermal noise, multipath distortion, and phase jitter. System signature is calculated for a system without any specific protection against multipath and for an IF (intermediate frequency) equalized system. Minimum-phase as well as nonminimum-phase fading... View full abstract»

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  • The prediction of the interference and service zones in the VHF/UHF tactical radio systems

    Publication Year: 1989, Page(s):441 - 444
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    A method for the prediction of interference and service zones for VHF/UHF tactical radio systems is proposed, developed, and illustrated by a few characteristic examples. It is noted that mathematical propagation models or more accurate computer-aided field prediction methods could be applied. A modification of a recently proposed statistical definition of the coverage area is applied to the servi... View full abstract»

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  • Propagation of surges in stator winding of large AC motors

    Publication Year: 1989, Page(s):138 - 141
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    The impedance and admittance matrices of the ten-turn coils of a 3.3 kV, 1 MW induction motor stator winding are calculated using a finite-element package. Using multiconductor transmission line theory the Z and Y matrices are manipulated to explain the modal propagation of step-fronted surges entering the winding. Some modes are seen to have similar structures in both the slot and overhang region... View full abstract»

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  • Inverters for utility interactive photovoltaic power plants

    Publication Year: 1989, Page(s):16 - 20
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (368 KB)

    An introduction to the more important inverter circuits for photovoltaic (PV) plants is presented. Their relative merits and drawbacks are examined, with particular emphasis on power quality, reliability, and efficiency. It is concluded that transistor circuits will probably conquer the small power field, whereas high-power converters will use thyristors and GTOs View full abstract»

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  • Properties of the momentum LMS algorithm

    Publication Year: 1989, Page(s):197 - 200
    Cited by:  Papers (1)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    The momentum least-mean square (MLMS) algorithm, a modified version of the well-known LMS algorithm, has recently been proposed, and an analysis of its basic convergence properties has been given. The authors revise the ranges of the MLMS algorithm's parameters, for which convergence is guaranteed, and provide precise expressions of convergence rate and steady-state performance of the algorithm un... View full abstract»

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  • A CAD/CAM system in an aeronautical industry

    Publication Year: 1989, Page(s):473 - 475
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (188 KB)

    The authors introduce a new CAD/CAM (computer-aided design/manufacturing) system. This system consists of five CPUs (micro-vaxes) and over 100 workstations (Interpro-Clipper), all connected through five Ethernet local area networks. The applications software is run either in the micro-vax or in the workstation. The goal is to organize and design a user environment that integrates the user's action... View full abstract»

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  • Variable speed AC-generators in wind energy convertors

    Publication Year: 1989, Page(s):91 - 94
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    The authors describe two variable-speed AC-drive systems: a synchronous generator with frequency converter for large speed ranges and a rotor cascade induction generator for small variations of speed. Results of transient state calculations using computer models and verifying laboratory tests are presented. The synchronous generator system together with a digital control system is being tested on ... View full abstract»

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  • Microwave large-signal amplifier design using a quasi-black-box transistor model

    Publication Year: 1989, Page(s):324 - 327
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    A method for the design of large-signal microwave amplifiers using a quasi-black-box transistor model is described. It is based on design maps, drawn on the basis of a suitable large-signal mathematical model of the transistor, which permit a straightforward search for the load reflection coefficient which provides maximum saturated output power or, alternatively, a good compromise between conflic... View full abstract»

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  • Transient response in homogeneous planar stratified media fed by a vertical electric source

    Publication Year: 1989, Page(s):505 - 508
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    The transient response of an infinitesimal electric current source, having a general time dependence and located in a planar grounded dielectric slab, is obtained by inverting the three-dimensional Fourier transform of the spectral dyadic Green's function associated with the integrated structure. Numerical examples are provided to investigate the behavior of the structure working under Gaussian pu... View full abstract»

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  • A new FH/MFSK receiver for stationary multitone jamming

    Publication Year: 1989, Page(s):436, 438 - 440
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    A novel FH/MFSK (frequency-hopping/M-ary frequency shift keying) receiver is proposed to operate under conditions of stationary multitone jamming. The principle of operation of this receiver relies on power measurements at all of the M-frequencies for each M -ary band before the signal is received in it. The performance of the receiver is evaluated by analytical methods ... View full abstract»

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  • Implementation of a RPE codec on a commercial DSP

    Publication Year: 1989, Page(s):213 - 216
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    The regular pulse excitation technique for speech coding at low bit rates provides good speech quality but involves a heavy computational effort. A novel method of reduced complexity is described which permits an efficient implementation on on a commercial DSP (digital signal processor) in terms of computation time and code compactness. The algorithm uses vector quantization for a vocal tract all-... View full abstract»

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  • Developments in the electrical machine laboratory at King Saud University

    Publication Year: 1989, Page(s):771 - 773
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (176 KB)

    The authors describe the process of updating and renewing the electrical machine laboratory at King Saud University that accompanied the movement of the University to its new campus at Dhareya. Particular attention is given to the old equipment that has been preserved and to the potential of the new equipment. It is noted that the research facilities may be improved if a computer system is introdu... View full abstract»

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  • The suitability of artificial intelligence techniques for the modeling and simulation of kinetic-electronic systems

    Publication Year: 1989, Page(s):135 - 137
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (172 KB)

    A methodology for modeling and simulating kinetic-electronic systems using artificial intelligence techniques is outlined. The methodology involves the coupling of numeric and semantic representations. The objective is to separate the simulation model responsible for the numeric computing from the knowledge system responsible for the semantic process. The semantic knowledge is processed by a Prolo... View full abstract»

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  • Maximum power point tracking technique

    Publication Year: 1989, Page(s):21 - 24
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (212 KB)

    It is noted that to overcome the problem of mismatch between solar cells and a given load, maximum power-point tracking should be used. A simple efficient maximum power-point tracking technique is developed. The connection strategy depends on a very simple criterion which is the measurement of the solar radiation level. The control strategy is based on appropriate logic that compares the signs of ... View full abstract»

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