K. Manivannan

Minimal multiplier realization of 2-D all-pass digital filters

A method is described to realize 2-D all-pass digital filters using a minimum number of multipliers. The multiplier values are real and are obtained as simple functions of the coefficients of the transfer function. It is shown that using this method one can realize a first-order 2-D all-pass filter with only three real-gain multipliers and three delays. >

Universal digital biquads which are free of limit cycles

Two second-order, multiple-output digital-filter structures are described which realize simultaneously a low-pass, a high-pass, a bandpass, a notch, and an all-pass transfer function. The two structures can be stabilized with respect to limit-cycle oscillations by employing the techniques of magnitude truncation and controlled rounding, and each uses four multipliers and two unit delays. The two structures are attractive for VLSI implementation since each can serve as the basis of a versatile, universal digital-filter chip which can be used for the implementation of Butterworth, Chebyshev, and elliptic digital filters and also for the design of digital equalizers.

Improved genetic algorithm solution to unit commitment problem

As the electrical industry restructures, many of the traditional algorithms for controlling generating units need modification or replacement. Previously utilized to schedule generation units in a manner that minimizes costs while meeting all demand, the Unit Commitment (UC) algorithm must be updated. This work deals with the Improved Genetic Algorithm (IGA) Solution to UC problem. The objective of this paper is to find the generation scheduling such that the total operating cost can be minimized, when subjected to a variety of constraints. A simple GA implementation using the standard reproduction, cross over and mutation operators has been utilized to get optimal solution. In this paper, we have obtained the satisfactory solutions for the UC problem using the varying quality function technique and by adding problem specific operators. The idea has been implemented using technical simulation package MATLAB and the results for the same were obtained. Neyveli Thermal Power Station - II in India, demonstrates the effectiveness of the proposed approach. Numerical results are shown to compare the superiority of the cost solutions obtained using the conventional methods.

An alternative sensitivity measure for designing low-sensitivity digital biquads

A sensitivity measure is proposed for determining the optimum set of machine-representable multiplier constants in the derivation of low-sensitivity digital biquadratic filters. A comparison of this measure with two other sensitivity measures of this class is then undertaken using four different design examples. The four sixth-order filters considered are a Butterworth low-pass, a Chebyshev high-pass, an elliptic bandstop, and an elliptic bandpass filter. It is shown that the three sensitivity measures usually give slightly different low-sensitivity designs and that the new sensitivity measure often gives the best design. >

Design of low-sensitivity universal wave digital biquads

A systematic procedure for the synthesis of low-sensitivity wave digital biquads is described. The procedure is based on the strategy of using, as far as possible, multiplier coefficients that are machine representable, so as to decrease the dependence of the amplitude response on multiplier coefficients that must be quantized. The procedure yields structures which can be stabilized with respect to zero- and constant-input limit-cycle oscillations. In addition, multiple-output structures can be obtained which realize simultaneously the standard second-order transfer functions. Experimental sensitivity wave digital biquad based on the three-amplifier RC-active configuration is less sensitive than other known low-sensitivity structures. Further, it is shown that by choosing the machine-representable coefficients, wave digital biquads can be obtained which are sensitivity-equivalent to other known low-sensitivity structures. >

Refined simulated annealing method for solving unit commitment problem

The objective of this paper is to find the generation scheduling such that the total operating cost can be minimized, when subjected to a variety of constraints with temperature and demand as control parameter. Neyveli Thermal Power Station - II in India, demonstrates the effectiveness of the proposed approach.

Optimisation of soft handoff margin in WCDMA cellular system

The focus of the paper is to analyse the downlink performance of a wideband code division multiple access (WCDMA) system with site selection diversity transmission (SSDT) power control during soft handoff (SHO) mode and to find the optimum SHO margin (M SH) in terms of maximum system capacity under energy-per-bit to noise spectral density ratio (E b/N 0) quality requirements. Analysing the dependency of the connection probabilities, percentage of users connected to one, two, or three base stations (BSs) simultaneously as a function of the M SH. We analysed the system capacity and required resources dependency on M SH for voice service and combined multimedia mobile services. System capacity dependency on M SH is analysed, by considering two types of user distributions, namely: 1) uniform user distribution; 2) a concentration of all the users in the location that requires maximum transmitted power (the worst case). The result of this analysis shows an increase in user capacity of about 16%-20% for the optimum M SH of 5-5.5 dB. Nevertheless, the resources required (number of scrambling codes) by the base station increases faster than the number of active users in terms of M SH.

Segmentation, Recognition and Synthesis of Tamil Characters for Robotic Writing

Currently, there are many ongoing researches that are targeted at making robots more human-like. In this paper, we are presenting a flexible algorithm that can allow a robot to write. This novel methodology includes two important phases namely, recognition of characters and writing of characters.Recognition is done via polynomial fitting. From a given text, each character is segmented, divided into five parts and decimated . These decimated samples are fitted to a polynomial of higher order and the coefficients of the polynomial are extracted as features of the character. These features are then compared with the standard template and are recognized. Writing is done via parametric equations, where the main idea lies in developing equations for each character. Each character is probed in a graphical sense and equations are obtained. Basic figures like cycloid, circle, spiral, ellipse, etc are studied and their features are utilised in developing equations. Thus, we obtain a set of primary equations for each character. By tracing this equation in a three dimensional environment, we get the required character.

Assessment of available transfer capability for practical power systems with margins

This paper describes the assessment of available transfer capability with capacity benefit and transmission reliability margins of practical power systems in a deregulated environment. It is a measure of unutilized capability of a transmission system subjected to wheeling transactions without violating transmission constraints at a given time and load. In this paper, a capacity benefit margin is incorporated by reserving power in five transmission lines. The transmission reliability margin is implemented by making any one of the transmission lines out of order at a time. Optimal generation and cost of generating units have been evaluated using evolutionary programming without violating transmission constraints, which has been tested using the Newton Raphson power flow algorithm. The proposed computation procedure of available transfer capability with margins has been tested and analysed for the IEEE-30 bus system. The solutions obtained are quite encouraging and useful in the present deregulated environment.

Allocation of power for Universal Mobile Telecommunication Services network during Soft Handoff

In order to provide a multiple services, especially multimedia and high-bit-rate packet data, Universal Mobile Telecommunication Services adopted Wideband Code Division Multiple Access (WCDMA) act as the mainstream air interface solution for the third-generation networks. An in-depth study of Soft Handoff (SHO) in the downlink direction of WCDMA network is carried out. The link-level study begins with the SHO effects on the downlink interference analysis and power allocation for each downlink-dedicated channel. To the users at the cell boundaries, the inter-cell interference is the main part of the total interference, especially with higher orthogonality. Simulation result shows that SHO decreases the probability of over-power Quality of Service (QoS) deterioration for the users at cell boundaries. However, 2-way SHO has a better performance than hard handoff and 3-way SHO, because it requires less dedicated power to meet the QoS for corner users.