Abdelhalim Zekry

The microthyristor could be a promising microelectronics device

In this paper, a new microthyristor structure suitable for microelectronics applications has been introduced. A suitable technology for its implementation has been chosen. The microthyristor has been designed and its performance has been simulated. The device showed superior performance concerning the switching times and the power dissipation in addition to controllability of its S-curve. During the development of this work, we introduced some new concepts such as doping-engineered devices, thyristor turn-off by shunting its cathode junction, and power consumption reduction by realizing high resistances. The basic requirements and some conditions are put together for successful launch of the microthyristor in microelectronics.

A fast CAD model of plasma spread in thyristors using a seminumerical time-domain approach

This paper presents a fast CAD model to calculate plasma-spreading velocity in large area thyristors. The model is based on the two-dimensional two-transistor circuit model of a thyristor. At first, a simplified numerical solution of the semiconductor equations is developed to obtain the current amplification factor and the base transit time of each transistor of the thyristor model as a function of the emitter current density. The turn-on recurrence relations governing the evolution of the anode current at different lateral points are then derived by the transit function method. The time constant of the anode current rise and the plasma spreading velocity are calculated as functions of the anode current density. The results of simulation are in close agreement with the corresponding measured values of plasma spreading velocity by the electrical probes method. This agreement confirms the validity of our model over a large scale of anode current densities.

Design of a Compact Dual Band Microstrip Antenna for Ku-Band Applications

ABSTRACT A new design of dual band compact microstrip antenna is proposed for Ku-band applications.Dual band is achieved using three pairs of thin slits from the sides of a rectangular patch and feeding with a microstrip feed line.The result shows that a return loss of -32.9dB is achieved at the first resonant frequency of 12.72GHz, and -14.4dB is obtained at the second resonant frequency of 14.4GHz frequency with VSWR ≤ 2indicating improved matching conditions. The results ofsimulation are return loss, radiation pattern, VSWR, and band widtharepresented. The design is performed by using Ready-madeSoftware package Zeland- IE3D. The antenna is fabricated using thin film and photolithographic technique and measured using the Vector Network Analyzer. The final result shows that good agreement between the simulated and measured results. Keywords Microstrip antenna,Ku-band, Dual band 1. INTRODUCTION Microstrip antennas have been one of the most innovative topics in antenna theory and design in recent years, and are increasingly finding application in a wide range of modern microwave systems [1]. Inherently they have numerous advantages like easy to fabricate using standard integrated circuit techniques, have microstrip lines [1low profile, are conformal, and can be easily integrated in arrays with electronic components. Nevertheless, microstrip antennas typically suffer from narrowband radiation (a few percent of center frequency), low gain, poor polarization purity, tolerance problem and limited power capacity. However, applications such as frequency tuning take advantage of the inherent narrow bandwidth of the microstrip antenna. Systems such as satellites, global position system(GPS) are required to operate at two different frequenciesthat are very far from each other. Microstrip antennas canavoid the use of two different single band antennas. A variety of methods has been proposed to obtain dual frequency operation. Such as loading slits [2], using slots in the patch [3], [4], loading the patch with shorting pins [5], [6] and [7], using stacked patches [8], [9], [10] and[11] or using two feeding ports [12] are the most exploited ones. In addition, there are planar antennas of special geometries fto achieve dual-bandoperation [13]. The Federal Communication Commission adopted a First Report and Order (First R&O) to permit non-geostationary satellite orbit (NGSO) and fixed-satellite service (FSS) providersto operate in various segments of the Ku-band, and adopted rules and policies to govern these operations. NGSO FSS can provide a variety of new services to the public, such as high-speed Internet access, other types of high-speed data, video and telephony services. Because of its ability to serve large portions of the earth’s surface, NGSO FSS can bring advanced services to rural areas. The Commission also adopted technical criteria so that NGSO FSS operations can share spectrum with incumbent services on a co-primary basis without causing unacceptable interference to them andwithout unduly constraining future growth of incumbent services or NGSO FSS system flexibility [14]. In this paper, a simple new compact design of single layer single patch element with microstrip feed line is proposed for dual frequency operation in Ku-band. The design and optimization resulted in a downlink frequency of 12.72GHz and uplink frequency of 14.4GHz. The most obvious application in the Ku-band is aircraft, spacecraft and satellite based communication system.

Intelligent Techniques for MPPT Control in Photovoltaic Systems: A Comprehensive Review

Photovoltaic (PV) electrical power generation, as one of renewable energy source, is a technique which uses solar energy to produce electric energy. The utilization of such systems is growing because of limited resources and the acute energy crisis. This motivates the research community to investigate these renewable energy sources and maximize their efficiency. This paper presents a literature survey from most recent achievements in maximum power tracking control AI algorithms. Maximum power tracking algorithms are used to match the load resistance to the source input resistance to increase the power delivered from the photovoltaic system. This paper compares between the works done in these algorithms concentrating on the AI algorithms which have proven higher efficiency in this field. The paper also states the most recent contributions in each algorithm. This manuscript should serve as a convenient reference for future work in maximum power tracking control.

Enhancing Channel Coding using AES Block Cipher

A key benefit of channel coding is the ability to protect data against channel impairments. Essentially, the channel coder adds redundancy bits that provide a way to correct corrupted data. Encryption is another way of protecting data against channel impairments and unintended interception or forging. This paper introduces an efficient approach of increasing coding gain at the receiver end. The implemented approach uses the advanced encryption standard (AES) cryptographic algorithm as a primary part of channel coding process. The simulation result of this implemented approach is evaluated in the presence of additive white Gaussian noise (AWGN).

A SPICE model of a thyristor with high injection effects and conductivity modulation

In this work a new SCR model is developed by applying the Gummel-Poon circuit model to the two-transistor configuration. This model naturally takes into consideration the high injection effects. Conductivity modulation is taken into consideration by using nonlinear current sources. The model parameters are defined and extracted according to a new methodology. The simulation results are compared with the measured results. The developed model satisfactorily describes the performance of the thyristor under practical operating conditions.

The Evolution of Aircraft Data Networks

paper presents the evolution of Aircraft Data Networks (ADN)s. It describes various Avionics data network protocols based on the Avionics systems architecture. The paper describes the evolution from a simple point-to-point protocol presented in ARINC 429 to a shared data bus protocol presented in ARINC 629. Finally, the new Data network based on AFDX (Avionics Full-duplex Ethernet) is discussed. AFDX is a new standard based on Ethernet technology and able to handle todays requirements. A brief comparison between the three different protocols is presented. The comparison shows that AFDX provides better performance and flexibility without losing the compliance with safety, redundancy and reliability of Avionics requirements

VHDL Realization of Efficient H.264 Intra Prediction Scheme Based on Best Prediction Matrix Mode

This paper introduces a VHDL realization of a new efficient intra prediction scheme that aims to enhance the compression efficiency of the H.264 standard. The new proposed algorithm is called Best Prediction Matrix Mode (BPMM). The main idea behind the new prediction scheme is to combine the most usable intra prediction modes,fvertical - horizontal - DCg, into a new efficient prediction mode. The performance of the new proposed prediction scheme with respect to compression ratio, Peak Signal to Noise Ratio (PSNR) and bit rate is evaluated. The results show that the BPMM enhances the compression ratio and correspondingly the bit rate and it noticeably increases the PSNR.

Design methodology and power conditioning circuit of vibration based MEMS converters for wireless sensor networks

This paper proposes a new design methodology for the MEMS energy converter to optimize its performance parameters in order to maximize its output power range and to validate charge transfer operation between the converter and the power conditioning circuit using the common circuit simulator SPICE. We developed a circuit model for the converter. An efficient transfer of charge between the reservoir and the converter has been found

Reduction of the current gain of the n-p-n transistor component of a thyristor due to the doping concentration of the p-base

The reduction of the current amplification factor of a wide-base transistor, with growing doping concentration in the base region, is investigated. A method for the determination of the minority-carrier lifetime tau /sub n/ in the base region and the emitter Gummel number G/sub e/ is developed. The method is based on transistor structures differing only in the base width. It was found that the lifetime tau /sub n/ decreases according to the power law tau /sub n/ approximately N/sup -0.45//sub A/. This result is analyzed for different recombination processes. Good agreement is obtained if shallow impurities acting as recombination centers are assumed. The injection-limited current gain beta /sub gamma / decreases significantly with an increase in the total number of the doping concentration of the base, reaches a broad maximum, and then falls slowly. The maximum value of G/sub e/ is found to be 1.1*10/sup 14/ cm/sup -4/-s in good agreement with theoretical results. Finally, the contribution of the injection efficiency gamma and the transport factor alpha /sub T/ to the current gain alpha are determined. It is found that alpha is limited mainly by the injection efficiency gamma . >