2006 International Conference on Electrical and Computer Engineering

Short circuit tests on circuit breakers are performed to prove the ratings of the circuit breakers. The drawbacks of direct testing using the power system or short circuit alternators: direct testing requires high power for testing CBs, high cost of installation, flexibility of the system available is limited and availability of limited power for testing of high voltage circuit breakers. Synthetic... View full abstract»

A very important matter of discussion in power system operation is the oscillations damping problem. In this paper the authors propose a fuzzy frequency controller (FFC) to improve the dynamic performance of a single-area power system. This paper represents the implementation of fuzzy frequency controller for an AGC in single-area power system. The aim of the proposed controller is to restore the ... View full abstract»

At present fuzzy logic control is receiving increasing emphasis in process control applications. This paper presents a self-adjusting, fast acting fuzzy gain scheduling scheme for conventional integral gain, K _I of automatic generation control (AGC) in a single area power system. The application of the fuzzy logic control on the performance of AGC is investigated. The integr... View full abstract»

In recent years, the immittance conversion topology (Oguchi et al., 2001) has become attractive as a novel power conversion strategy because of its features that a constant voltage source is converted to a constant current source and vice versa. However, the design of an ideal immittance circuit in the high-power (~kW) and high-frequency (~MHz) range is practically very important, especially when ... View full abstract»

This paper demonstrates the electromagnetic behaviour of transient response of lightning surge strike on vertical tower for wireless communications and power systems. Vertical tower surge responses are analysed using electromagnetic transient program (EMTP). The accuracy of this method is shown to be satisfactory with the simulation result based on the numerical electromagnetic code (NEC-2) that w... View full abstract»

In this paper, equal embedded algorithm is used to solve dynamic economic dispatch problem. This problem satisfies the load demand over a certain period of time and some practical operation constraints of generators such as ramp rate limits. The proposed method was tested on a power system having 6 and 15 generating units with ramp rate limits. The results obtained by the proposed method were comp... View full abstract»

Development in electrical power transmission system requires the use of circuit breakers with increasing breaking capacity. At present circuit breakers are to be installed on 245kV to 760 kV power systems with short circuit ratings up to 63kA. To test high voltage CBs, direct testing using the power system or short circuit alternators is not feasible. The testing of high voltage CBs of larger capa... View full abstract»

Trapping in microwave devices affects the time domain and frequency domain behaviour. In the time domain, surface traps result in the well known gate lag effect. A model, developed to predict these effects in HEMT devices, is used to simulate frequency domain behaviour of trapping in HEMT device. Trapping is known to cause distortion in intermodulation behaviour of the device, that is, a null in t... View full abstract»

The multiplication process is a stochastic event and induces noise as a result of describing random path lengths in ionizing atoms. The noise factor is examined for short devices where the multiplication of carriers is confined to very short length. It is seen to be affected, in contrast to the large devices, by the dead space effect. In the present paper random path length (RPL) model is introduc... View full abstract»

We have analyzed the four-wave mixing (FWM) characteristics with optimum time-delays between pump and probe pulses in semiconductor optical amplifiers (SOAs) by the finite-difference beam propagation method (FD-BPM). The study of FWM characteristics with optimum time-delays between pump and probe pulses in SOAs has the importance to achieve the high FWM conversion efficiency and to clarify the tim... View full abstract»

Calculation of the strain relaxation in membrane GaInAsP/InP quantum wire laser is performed using finite element method. Effect of strain-compensating barriers in multiple quantum wire stacks on the strain relaxation is investigated using both isotropic and anisotropic models. It is found that the difference between the two results increases when the wires are narrower and this effect is more pro... View full abstract»

This paper describes the integration of vertically aligned carbon nanofibers (VACNF) with the CMOS integrated circuits fabricated with commercial CMOS processes. The growth temperature of VACNF is about 700degC (Merkulov et al., 2001) which is well above the maximum operating temperature of CMOS circuits. In order to integrate VACNF with CMOS circuits, a method is described to transfer the separat... View full abstract»

This report describes a new modification technique of tungsten tip, which results a tip apex capable of emitting electrons at extremely low bias voltages. By employing positive electric field the structure of the tip apex is switched in presence of oxygen followed by freezing out the modified structure at low temperature. Thus modified tip exhibit an extraordinary two orders decrease in applied bi... View full abstract»

A fully micromachined single mode 2times2 cross-bar optical switch based on noble piezoelectric actuation has been designed and simulated for small volume, low insertion loss and low switching voltage. Piezoelectric unimorph bender was used for actuating the micromirror of the switch. The performance of the switch was simulated in MATLAB. The required tip displacement of the micromirror had found ... View full abstract»

A base transit time model for an npn bipolar junction transistor with exponential-doped base at high level of injection, which is applicable for all levels of injection before the onset of the Kirk effect, is developed. Based on the realistic assumption that a small change in electron concentration in the base at high injection occurs from its modified low injection model incorporating Webster eff... View full abstract»

An efficient genetic algorithm (GA) assisted bit error rate (BER) monitoring in digital communication link using a sum of Gaussian approximation (SGA) to the non-Gaussian link output variate is presented. The validity of the proposed method is established by both theory and experiment in three specific scenarios viz. non-coherent amplitude-shift-keying, misaligned optical transmitter-receiver syst... View full abstract»

Orthogonal frequency division multiplexing (OFDM) is an effective multicarrier modulation technique for high speed data communications which suffers from high peak to average power ratio (PAPR). And Wireless broadband (WiBro) is to provide high data rate wireless Internet access with PSS (personal subscribe station) under the stationary or mobile environment, anytime and anywhere for the future 4G... View full abstract»

This paper proposes multiuser channel estimation techniques for space time block coded-orthogonal frequency division multiplexing (STBC-OFDM) systems based on simple blocked pilot grid. The estimation of multiuser channels is based on least square (LS) and minimum mean square estimation (MMSE) schemes. Simulation results, for a slowly faded quasi-static channel, reveal that the estimated character... View full abstract»

With the increase in the spectral congestion and dramatic enhancement in the numbers of mobile telephone users, many approaches are being considered to reduce the bandwidth requirement of each user. One approach is the use of quadrature amplitude modulation (QAM) for mobile radio applications. QAM multilevel modulation can offer an attractive solution to current bandwidth restriction in microcellu... View full abstract»

This paper considers residential power line as communication channel for high speed power line communication (PLC). Power line is analysed according to transmission line theory. Four channel parameters: attenuation constant, phase constant, phase velocity, and group velocity are formulated as a function of characteristic impedance. The high frequency characteristics of these parameters are simulat... View full abstract»

MIMO systems, employing array of antennas at both ends of the transmission link, provide significant increase in the achievable capacity. The ability of achieving this high capacity is greatly influenced by the geometry of antenna array used and the correlation between the channel gains on each antenna element in the array. In this paper, the impact of different array configurations have on capaci... View full abstract»

This paper focuses a new public network for BTTB able to spread IP communications to provide value added services which is a demand of the age. Considering the popularized IP communications, together with the trend of communication technologies, the evolution to an all-IP infrastructure have impacts on the service layer. The arrival of Internet protocol (IP) based transport and switching technolog... View full abstract»

A comparison between path and span protection schemes has been carried out for a just-enough-time based optical burst switched network in case of single link failure utilizing the network link state information. Further, depending on the type of protection strategy and traffic load, the wavelength resource requirement has also been evaluated maintaining a desired network burst loss probability View full abstract»