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Electrical and Electronics Engineers in Israel, 2002. The 22nd Convention of

Date 1-1 Dec. 2002

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Displaying Results 1 - 25 of 138
  • 22nd Convention of Electrical and Electronics Engineers in Israel. Proceedings (Cat. No.02EX637)

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    Freely Available from IEEE
  • Author index

    Page(s): 358 - 359
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    Freely Available from IEEE
  • Queueing analysis of Markov modulated ON/OFF arrivals with geometric service times

    Page(s): 189 - 191
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    There has been extensive work focused on modeling discrete-time queueing systems with correlated arrivals. Specific attention has been drawn to queueing models with application to data switching, where bursty arrival streams represent more accurately real-life network traffic. To that end, the Markov modulated ON-OFF model has been frequently incorporated as a building block for constructing more complex traffic scenarios. In order to better evaluate the performance of a given switching system under bursty traffic, many packet-scheduling algorithms are examined under traffic obeying Markov modulated arrival processes. In some cases, significant degradation in performance metrics, such as the mean queueing latency, is observed under such bursty scenarios. Typically, performance metrics for switching systems under bursty traffic loads are attained by means of simulations. In this paper, we present an analytical tool that exploits the probability generating function of the interarrival times for obtaining steady-state queueing information from which performance metrics are analytically derived. View full abstract»

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  • Direct-sequence spread-spectrum fast acquisition architectures in the presence of time and frequency uncertainty

    Page(s): 192 - 196
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    This paper presents, a comprehensive coverage of direct-sequence spread-spectrum fast acquisition techniques and architectures, their performance and complexity. A TDMA/CDMA transmission structure is presented as a burst of direct sequence spread spectrum signals. Fast parallel acquisition architectures are overviewed, examined, and compared in the perspective of performance and complexity. New architectures are presented, showing tradeoff between performance and complexity. The architectures evaluation is made from a novel point of view. It is based on the acquisition success probability in a finite time, instead of evaluating the traditional T~aq. All architectures use parallel processing with sequence matched filters, partial sequence matched filters, and FFT algorithms. View full abstract»

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  • Adaptive loading for multitone version of V-BLAST

    Page(s): 197 - 199
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    The demand for high data rate communication systems and the lack of available bandwidth has led to much research effort into MIMO systems using multiple transmit and receive antennas. It has been shown that MIMO systems can improve the capacity of rich Rayleigh fading channels by a factor which is linearly proportional to the minimum number of transmit and receive antennas. The V-BLAST architecture has been proposed for realizing high spectral efficiencies over flat Rayleigh fading indoor wireless channels. Multitone transmission, or OFDM, has been used in a number of systems. OFDM eliminates the need for a complex equalizer for overcoming ISI caused by delay spread or frequency-selective fading. However, it has been shown that for a single-input-single-output (SISO) system operating over a frequency-selective channel, if the transmitter "knows" the channel characteristics, the "water-pouring" technique can be used to optimize the transmitted bit rate and approach the channel capacity. In this paper, we use the "water-pouring" approach for combined OFDM-MIMO systems, and show that it is possible to achieve very good bandwidth efficiencies for un-coded systems. View full abstract»

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  • Accuracy of frequency estimation in conoscopic holography

    Page(s): 170 - 171
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    Conoscopic holography enables us to carry out precise distance measurement by non-contact methods. The distance between the ConoProbe and the point on the measured object where the laser beam strikes the surface, is determined by the frequency of fringes produced by the holographic image. The quality of measurement depends on a number of parameters of which the variation of frequency estimation is probably the most important. The purpose of this work is to evaluate errors in frequency estimation using statistical simulation. View full abstract»

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  • On strongest-users-only detectors for DS-CDMA cellular systems

    Page(s): 20 - 22
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    The fundamental figure of merit that specifies the ultimate performance of cellular systems is the per-cell spectral efficiency. The underlying tacit assumption in previous spectral efficiency analyses is that all active users are (reliably) decoded, regardless of their received powers. Unfortunately, in practice, this assumption may not hold and we consider an alternative approach. Assuming single cell-site processing, four types of multiuser detection strategies are considered: (1) the "conventional" matched-filter detector; (2) the linear MMSE detector; (3) a detector that "optimally" decodes the transmissions of the maximum decodable subset of intra-cell users, referred to as the "single-cell optimum (SCO) detector"; (4) an "optimum" detector referred to as the "single cell-site processing optimum (SCPO) detector". The strategies are analyzed and compared in terms of their outage constrained capacities, analytically derived as functions of the fraction of undecodable users (FUU), equivalent to the outage probability. View full abstract»

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  • Performance of concatenated Reed-Solomon and TCM over DMT modulation

    Page(s): 308 - 310
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    In discrete multi-tone (DMT) modulation the information is conveyed using a set of tones. Each tone is modulated by a complex quadrature amplitude modulation (QAM) symbol and transmitted for a fixed time interval. In order to enhance the reliability of the system a concatenated coding scheme is often used: trellis coded modulation (TCM) as the inner code and Reed Solomon (RS) as the outer code. This coding scheme is used in DSL modems, particularly in ADSL. One of the basic performance measures of the system is the bit error rate (BER). Usually the designer is given the signal to noise ratio (SNR) distribution over the available set of tones, and is asked to find the BER for a given bit allocation, or to optimize bit allocation under the constraint of maximal BER. Performance analysis of the concatenated coding scheme is quite difficult and often it is necessary to use approximations, which have limited accuracy. In this work we develop a computational procedure to solve the BER estimation problem. The procedure is based on two steps. The first step is a recursive computation of the probability of the occurrence of a certain number of RS symbol (byte) errors in an RS codeword. The second step is based on a finite state machine (FSM) description of the TCM decoder output. We also discuss the extension of this scheme to a finite D-way interleaver. View full abstract»

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  • Time-scale modification of music signals

    Page(s): 254 - 256
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    Time-scale modification (TSM) of audio signals is the process of modifying the rate of audio signals such as speech or music, while maintaining other parameters (pitch, timbre) unchanged. It is a subject of major theoretical and practical interest. In this study, a new algorithm for time-scale modification of music signals is presented. The proposed algorithm is related to the PSOLA-like algorithms, which are based on the similarity of the short-time Fourier transform between the original and the timescaled signal. The basic assumption of these algorithms is that the spectral characteristics of the signal are constant for short durations, and that the signal is quasi-periodic in the time domain. The signal in PSOLA is divided into short-time overlapping frames, which are used for constructing the time-scaled synthesis signal, while maintaining the original spectral parameters and their related location. View full abstract»

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  • On the capacity-achieving distribution of the discrete-time non-coherent and partially-coherent AWGN channels

    Page(s): 148 - 150
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    We investigate the ultimate communication limits over rapid phase varying channels and consider the capacity of a discrete-time non-coherent additive white Gaussian noise channel under the average power constraint. We obtain necessary and sufficient conditions for the optimal, capacity achieving, input distribution and show that the optimal distribution is discrete and possesses an infinite number of mass points. In addition, we provide some easily computable lower and upper bounds on the channel capacity. Some of these results are extended to the partially coherent channel, where a phase locked loop (PLL) is used to track the carrier phase at the receiver, and where the residual phase errors are assumed to be Tikhonov distributed and statistically independent. View full abstract»

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  • Sensorless speed and direct torque control of surface permanent magnet synchronous machines using stochastic filtering techniques

    Page(s): 39 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    The paper describes the development of a sensorless speed and direct torque control system for surface permanent magnet synchronous machines (SPMSM). An extended Kalman filter (EKF) is used for the stator flux and mechanical state estimation of the SPMSM. The observer was developed based on a nonlinear model of the synchronous machine that employs α-β stationary reference frame. The torque controller was designed taking into consideration a model of the machine in the rotating reference frame attached to the stator flux space vector. The electromagnetic torque and stator flux, are controlled by nonlinear hysteresis controllers; their output signals are used for generating the control signals of inverter, based on a switching table. The angular speed controller is linear of I + PI type. View full abstract»

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  • Shielding against magnetic fields radiated from high power transformers

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    Summary form only given. Large buildings for commercial, educational and residential purposes require a local power plant for air conditioning, elevators and other uses. These power plants are high power transformers with a three phase high voltage input and a low voltage/high current three phase output. These high current outputs generate an intense local magnetic field, above the accepted ICNIRP exposure limits. This paper examines the specific sources of these fields and provides design methods and practical solutions to reduce these fields to an acceptable value in the vicinity of the power plant. View full abstract»

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  • The solar assisted "Intelligent" building-a revolution in the modern low-energy constructions' conception

    Page(s): 273 - 276
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    Renewable energies and especially solar energy are not a really new subject. Even in past historical times it seems that this and other natural energy resources were used to produce mechanical or other kind of work. Without entering the mode of usage and the specific appliances, we can note only that ancient people knew really much more about solar energy than we suppose they knew. In past modern times, solar energy was used by August Mouchot to drive a steam engine at the Universal Exposition in Paris in 1878 and Ericsson built a number of solar driven engines, the largest being capable to produce 2.5 kW, between 1875 and 1885. Solar energy is today largely used in developing countries, in arid and isolated areas to produce householding electricity. This will be the fuel of the future. Mankind's reserves of conventional fuels are close to their red line. We have to think about the energetic future of the coming generations. This future - indubitably - will be a solar one. View full abstract»

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  • Design and implementation of a μLAN network

    Page(s): 228 - 230
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    μLAN is a generic communication network protocol designed to provide a functionally-correct, reliable communication between the various components of a digital system. The μLAN network described in this paper can be used in a large variety of digital systems that contain more then one programmable logic device. Its simple and easy to use design flow reduces the effort invested in defining and implementing new and specific protocols and interfaces for every design, thus reducing the cost and time to market of designs. The μLAN network has advantages over other interface protocols between programmable logic devices in the market by having built in routing capabilities and protocol layer definitions and implementation. View full abstract»

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  • Study and development of a high-power, high-voltage nanosecond pulser

    Page(s): 32 - 34
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    Energy compression techniques are analyzed. A most advanced method is a combination of magnetic and fast semiconductor switching. An equivalent circuit of an inductive storage semiconductor opening switch (SOS)-based pulser was developed and analyzed using a PSpice platform. It comprised a number of nonlinear elements representing all-solid state switches and saturation inductors and transformers. An extensive experimental study of the described technique was performed using an SM-4N SOS-pulser yielding 50 MW 20 ns pulses. Electrical diagnostics means for monitoring nanosecond HV pulses was developed. It comprised specialty capacitive dividers, current shunts and transformers and Rogowski coils. The pulser was characterized both with an ohmic and gas discharge load. It was found that simulation and test results are in a fair agreement for a resistive load. The simulation model will be used for design of a high-power pulser intended for driving a pulsed corona discharge. View full abstract»

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  • CMOS based β-driven threshold elements with functional inputs

    Page(s): 111 - 113
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    We describe a CMOS implementation of a β-driven threshold element. Using such an element as a functional basis of artificial neurons has a number of advantages in comparison with the traditional functional basis. In this paper we focus on extension of the functional capability of the threshold element. We introduce functional inputs into the β-driven threshold element to allow increase of its functional capability up to the capability of realizing every monotonic Boolean function. We present an implementation of the β-driven threshold element, having the proposed functional inputs, by a CMOS circuit. SPICE simulation results demonstrate the high efficiency of the solutions and consequently motivate further investigations of artificial neurons based on β-driven elements. View full abstract»

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  • New power factor correction and current harmonic mitigation for AC variable reluctance generator with DC excitation

    Page(s): 156 - 158
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    The present paper proposes a new approach to compensate the inductive voltage drop on the internal inductance of the AC variable reluctance generator with DC excitation (AVARGED) and also to compensate the higher voltage harmonics produced in it. As a result, the output current and the associated output voltage on a resistive load are sinusoidal waves in phase with fundamental harmonic of the electro-motive force and without any higher harmonics. View full abstract»

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  • Diagrammatic reasoning with statecharts: a cognitive approach for software/systems engineers

    Page(s): 98 - 100
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    The behavior of reactive systems can be rigorously specified and verified via mathematical notation, such as temporal logic. However, for all but the simplest models, it is difficult for the reader to understand the intent of the model, and, for that matter, may be difficult for the model designer to accurately specify the desired behavior. Visual or "iconic" models have addressed this difficulty. Modeling tools typically include a mock-user interface builder and a graphical behavioral specifier, typically in the form of a Statechart editor (typical examples of such tools are Mathworks, Rapid, Statemate and Rhapsody). Statecharts solved the problem of combinatorial state explosion via encapsulation of OR and AND states. However, in order to minimize the corresponding transition explosion, Statecharts freely use global (i.e., global with respect to the Statechart) events and transitions that transcend state hierarchical boundaries. The paradoxical utilization and violation of encapsulation makes it difficult to apprehend the intent of even relatively simple Statecharts. We expound a pattern-based cognitive approach to this problem. View full abstract»

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  • Human epileptic seizure prediction with fuzzy clustering of wavelet and polyspectra-based features of the EEG

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    Summary form only given. Epileptic seizures affect about 1% of the human population. Many patients (20%) are resistant to preventive drug treatment. The ability to anticipate the onset of seizures in such cases would permit clinical intervention. In previous work, the unsupervised optimal fuzzy clustering (UOFC) algorithm was applied to wavelet coefficient features in predicting hyperbaric-oxygen-induced generalized epileptic seizures in rat EEG. The two phases have the ability of processing and identifying transients (spikes), as well as long-term activity. In 16 instances, a pre-seizure state, lasting between 0.7 and 4 minutes, was defined. Projecting these results to human epilepsy is uncertain, given the different origin of the seizure as well as species differences in cerebral organization. In the present work, we attempt to predict spontaneous focal seizures in the EEG of epileptic patients who are monitored for surgical intervention. The UOFC is applied to two main classes of features: Fourier-transform based features (polyspectra) and multi-resolution based features (wavelets and multi-wavelets). Cluster formation shows the ability to detect 88%-100% of the 25 focal seizures and a prediction rate of in about 30% of the seizure, all using the wavelet coefficients as features. Less promising results were obtained using Fourier based features. View full abstract»

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  • A physiological adaptation model and its predictions for different color induction effects

    Page(s): 353 - 356
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    A comprehensive computational biological model based on physiological retinal and cortical color-coded receptive fields and physiological adaptation mechanisms of the first and second order is presented. This order of color processing, of first dealing with the color and then with the color contrast, has a computational advantage, since color correction and enhancement become more cost-effective. The model's prediction of complementary color by color induction is not in agreement with previous suggested mechanisms, the suggested neuronal locus of the mechanism and the assumptions of previous studies that assumed that a complementary effect cannot be derived from an opponent receptive field type. The model succeeds in predicting psychophysical contrast-contrast dual effects. It was also suggested as a cortical chromatic physiological mechanism which has computer vision applications as well. As far as we know, most of the physiological or psychophysical chromatic computational models have not been applied to real images, except for a recent model of D'Zmura and Singer. Which performed gain control equalization. This application shows a pronounced effect (equalization of contrast) only after repeated applications of the contrast gain model. View full abstract»

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  • Synthesis of broadband dynamic optical equalizers

    Page(s): 172 - 174
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    We describe a novel approach for synthesizing a desired response using an optical lattice equalizer. We demonstrate the simultaneous compensation of polarization mode dispersion (PMD) in 5 channels by minimizing the maximum differential group delay (DGD) across the band. The same approach can be applied to equalize other transmission parameters of the communication channel such as the chromatic dispersion (CD) and the gain. View full abstract»

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  • Standardization in ITU-T

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    Summary form only given. The paper describes activities and experience of ECI in telecommunications standardization, especially in the ITU-T. We start by describing the market and motivation, other bodies active in the field, and the difference between them and the ITU-T. The method of operation of the ITU-T is described, followed by examples of the standardization activities involved within the development of marketing efforts of some of ECI's products. For ECI the standardization activities are considered to be a must. Why and how is explained. View full abstract»

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  • Self-regulated PTC mini burner embedded in a catheter, PTC blood flow sensor and PTC cautery scalpel-like device, for cardiac procedures

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    Summary form only given. A novel positive temperature coefficient (PTC) self-regulated heat generating device was developed. Three options were proposed for this self-regulated heater: a scalpel-like device for surgical applications; a PTC mini burner embedded in a catheter at its tip; and a PTC blood flow sensor. The scalpel-like device is capable of maintaining a constant temperature and variable heat generation along with coagulation capabilities for human and veterinarian surgical, medical and dental use. The PTC mini burner, embedded at a catheter tip is used for internal tissue local burning. The PTC blood flow sensor size is infinitesimal. As the temperature is preset to a certain value, thermal load is measured. A first derivative (in the time domain), of the thermal load readout, gives the blood flow (l/min). View full abstract»

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  • Allocating and splitting switchboard crews by urgency of calls

    Page(s): 207 - 209
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    Of all the calls made by Israelis to police emergency switchboards no more than 18% are genuinely urgent. The remainder are either requests for information or nuisance calls. Nonetheless, under the current system, all operators deal with all types of calls that are taken in FIFO order: that is, giving each call equal priority. But since callers in fact want different sorts of service of varying levels of urgency, applying FIFO order means that genuinely urgent calls may have to wait too long before being answered. One solution to the problem is to classify calls by urgency level and to allocate more operators to the urgent group. Response to urgent calls is thus improved at the expense of the less urgent ones. The study presented here examines the possibility and value of splitting a switchboard (SWB) and its operator team into two, for urgent and for non-urgent calls, and describes a model developed for calculating the proportion of the total operator team required for each of the two SWBs. The study also clarifies the relation between the urgency of calls and operators' level of occupation. View full abstract»

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  • Domain decomposition and non-uniform spherical grid interpolation (NSGI) algorithm for fast solution of potential problems

    Page(s): 86 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    A novel scheme facilitating numerically efficient evaluation of the potential produced by a given charge distribution is presented. The algorithm is based on the observation that locally the the potential produced by a finite size source is an essentially bandlimited function of the angles and a polynomial in the reciprocal radial distance. Therefore the potential can be interpolated from its samples at a small number of points of a nonuniform spherical grid. With this in mind, the problem geometry is decomposed into hierarchy of subdomains. Potential computation is performed separately for charges residing in each subdomain on the finest level. The proposed multilevel algorithm comprises interpolation and aggregation of potentials for each group of subdomains to compute the potential of a larger parent subdomain. The resulting hierarchical algorithm attains an asymptotic complexity of O(N). View full abstract»

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