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SUMMER-FALL 2003

Table of Contents


Editorial Note


SPECIAL SECTION ON COMMUNICATIONS:


Designing M-Channel IIR Uniform DFT Filter Banks Using Interpolated IIR Technique

M. J. Dehghani, K. M. M. Prabhu, and R. Aravind

PP. 61-68 

Reservation Aloha Algorithm With Adaptively Prioritized Controlled Capture

Mohamed Hadi Habaebi and Borhanuddin Mohd Ali

PP. 69-74 

FDSS Overlay on AMPS System Using Subchannel Suppression, Down and Up Link Analysis

Bazil Taha Ahmed, Miguel Calvo Ramón, and and Leandro de Haro Ariet

PP. 75-79 

Shaped W-CDMA Cells Performance in Highways (General Case)

Bazil Taha Ahmed, Miguel Calvo Ramón, and and Leandro de Haro Ariet

PP. 80-84 

Systematic Modeling of MESFETs Using Only Normal Bias Measurements

Mohammad Khalaj Amirhosseini

PP. 85-89 


REGULAR PAPERS:


New Approaches for Size Determination of Apple Fruits for Automatic Sorting and Grading

P. Sudhakara Rao and S. Renganathan

PP. 90-97 

Evaluation of Partial Discharge Activity by Expert Systems

Karel Zalis

PP. 98-105

Nonlinear Dynamics and Chaotic Behavior of a Resonant DC-DC Converter

Daniel Curiac, Octavian Dranga, and Florin Dragan

PP. 106-110

Time Series Prediction with Finite Performance Bounds

Ge Guo and Zhan T. Yuan

PP. 111-115

 


CALL FOR PAPERS:


Special Section on
Information Technology and Its Applications

 


Abstracts



Designing M-Channel IIR Uniform DFT Filter Banks Using Interpolated IIR Technique

M. J. Dehghani, K. M. M. Prabhu, and R. Aravind

Electrical Engineering Department, Indian Institute of Technology Madras, Indian


Abstract: This paper introduces a method of designing an M-channel, causal, stable and perfect reconstruction (PR), infinite impulse response (IIR), parallel uniform discrete Fourier transform (DFT) filter banks. The basic idea behind this is based on an efficient technique of designing and implementing narrowband lowpass finite impulse response (FIR) filters, called the interpolated FIR (IFIR) technique. In this paper, we have extended the IFIR concept to the IIR filter, known as Interpolated IIR (IIIR), and applied the concept to IIR DFT filter banks. It has been shown that this technique is good for IIR DFT filter banks in polyphase oversampled case and also has a modular structure which is therefore very useful for very large scale integration (VLSI) implementation.





Reservation Aloha Algorithm With Adaptively Prioritized Controlled Capture

Mohamed Hadi Habaebi and Borhanuddin Mohd Ali

Department of Computer & Communications
Engineering, Universiti Putra Malaysia, Malaysia


Abstract: In this paper, we introduce a new mixed priority scheme that utilizes the logarithmically equi-spaced random transmitter power levels (LESRTPL) model to control the assignment of the transmitter power levels, assigned to each priority class, adaptively. Packets, of different priority classes contending simultaneously over the wireless channels to capture a contention slot, will transmit using LESRTPLs set pre-assigned to them using an adaptive prioritized controlled capture (APCC) scheme. Higher priority classes are assigned stronger power levels according to their priority index and the estimated number of backlogged packets on the frame. The wireless channel capture model includes Rayleigh fading, shadowing, and path loss. The throughput of the algorithm is analyzed and its delay performance evaluated using simulation models. Results show that the new priority scheme offers significant improvement to the throughput and the waiting time of the different priority classes over Basic Aloha Algorithms, especially to high priority class packets.





FDSS Overlay on AMPS System Using Subchannel Suppression, Down and Up Link Analysis

Bazil Taha Ahmed, Miguel Calvo Ramón, and and Leandro de Haro Ariet

Departamento Sistemas, Senales y Radiocomunicaciones,
Universidad Politécnica de Madrid, Spain


Abstract: The overlay of a frequency diversity spread spectrum system (FDSS) on the advanced mobile phone service (AMPS) system is studied. The worst case condition is considered. The down- and uplink capacity for both systems are given using a model of 25 cells. The performance of the AMPS and FDSS users is investigated. Results show that the overlay is feasible when a good selection of the overlay parameters is done.





Shaped W-CDMA Cells Performance in Highways (General Case)

Bazil Taha Ahmed, Miguel Calvo Ramón, and and Leandro de Haro Ariet

Departamento Sistemas, Senales y Radiocomunicaciones,
Universidad Politécnica de Madrid, Spain


Abstract: The capacity and the interference statistics of the sectors of the shaped W-CDMA cell are studied for the general form of microcell (Cigar-shaped, T-shaped and Cross-shaped). A model of 5 cells is used to analyze the uplink, which limits the capacity. The cells are assumed to exist in rural zones. Results that show the capacity and the interference statistics of the cell are given for different breakpoint distances, different propagation exponent and different antenna side lobe levels when the microcell is of cigar-shaped form.




Systematic Modeling of MESFETs Using Only Normal Bias Measurements

Mohammad Khalaj Amirhosseini

Electrical Engineering Department, Iran University
of Science and Technology, Iran


Abstract: Analysis of both small-signal and large-signal circuits, requires small-signal modeling of their elements in one and several biases, respectively. In this paper, we present a systematic method for extracting a small-signal model of MESFETs using S parameters measured only in normal bias and in two frequencies. This method is examined for a low-noise MESFET in L and S band.




New Approaches for Size Determination of Apple Fruits for Automatic Sorting and Grading

P. Sudhakara Rao* and S. Renganathan**

* CEERI Chennai Centre, CSIR,, India

** Madras Institute of Technology, Anna University, India


Abstract: Nondestructive quality evaluation of fruits is important and very vital for the food and agricultural industry. The fruits in the market should satisfy the consumer preferences. Traditionally grading of fruits is performed primarily by visual inspection using size as a particular quality attribute. Image processing offers solution for automated fruit size grading to provide accurate, reliable, consistent and quantitative information apart from handling large volumes, which may not be achieved by employing human graders. A fruit grading system based on machine vision technology to assess the fruits quality would bring economical benefits to the fruit industry by increasing consumer/buyer confidence in the quality of the fruit.


Conventional methods of size determination are not suitable for objects of irregular shape. Majority of the apples have good degree of symmetry about the stem and calyx axis. The paper discusses three different methods to determine the size of this category of apples by applying the known geometrical models. Three more methods are presented in the paper to determine the size of the other category of apples. The Apple fruit images in different postures are captured to cover the entire fruit, using a CCD camera. The analysis is carried out using MATLAB® package on Windows® platform. It was found that though all the methods outlined in the paper could be used, some methods achieve higher performance..




Evaluation of Partial Discharge Activity by Expert Systems

Karel Zalis

Department of Electroenergetics, Czech Technical
University in Prague, Czech Republic


Abstract: Insulation systems are one of the most exposed parts of electrical machines and equipment. Special diagnostic methods have been developed not only to detect defects and anomalies in high voltage (HV) insulation systems, but also to evaluate the state of the systems with regard to further service reliability. Following the results of diagnostic methods, it is possible not only to determine the reliability of the equipment in subsequent service but also to prolong the inspection periods, or to reduce the number of inspections.


Expert system with the elements of artificial intelligence is a very effective tool for the evaluation of measured data from the diagnostic measurements and for the estimation of behavior of the insulation system in future operation. Several rule-based expert systems for the diagnostics of HV insulation systems have been developed at the Czech Technical University in Prague in the collaboration with other top diagnostic workplaces of the Czech Republic.


A complex system for the partial discharge (PD) evaluation, based on digital data processing, has been developed. Detected analog PD impulses are digitized in the measuring unit by a special analog-digital converter and the connection between the measuring unit and the computer enables to transfer detected PD impulses immediately into a computer for their further processing. Two parallel expert systems work in this complex evaluating system: a rule-based expert system performs an amplitude analysis of PD impulses for determining the damage of the insulation system, and a neural network is used for a phase analysis of PD impulses (the recognition of PD patterns) to determine the kind of PD activity and location of the resource of PD activity.




Nonlinear Dynamics and Chaotic Behavior of a Resonant DC-DC Converter

Daniel Curiac*, Octavian Dranga**, and Florin Dragan*

* Department of Automation and Applied Informatics, Politehnica, University of Timisoara, Romania

** Department of Automation and Applied Informatics, Budapest University of Technology and Economics, 1111 Budapest, Hungary

Abstract: The paper reports subharmonic and chaotic operation in one member of a new double channel resonant DC-DC converter family. The converter can operate both in symmetrical and in asymmetrical mode. Our investigation is restricted to the buck configuration in symmetrical operation.


After a brief summary of the configuration and its basic operation the paper is concerned with some nonlinear phenomena of the output voltage control loop of the resonant buck converter. The nonlinearity is due to the dependence of the turn-on time of the controlled switches on a system state variable. The feedback controlled converter exhibits rather strange behavior, which is studied by computer simulations. As a result of the switching train our nonlinear dynamic system can be in periodic, subharmonic and chaotic state reached by a period doubling scenario. The paper presents a number of simulations results of this behavior in form of time functions, bifurcation diagrams and Poincaré maps.


The analysis presented in the paper allows a practical overall picture of the converter behavior, to help the designing engineer and to search for stable periodic regions and settings.


ISSN: 1682-0053
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