Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)最新文献

{"title":"Reconstruction of the dyadic dielectric constant profile of anisotropic inhomogeneous media","authors":"A. Omar","doi":"10.1109/NRSC.1999.760869","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760869","url":null,"abstract":"The dyadic dielectric constant profile in a general inhomogeneous and anisotropic object can be uniquely reconstructed by a series of near field measurements of the scattered field resulting from illuminating the object by electromagnetic waves with properly chosen properties. This can be made either in the time domain, if the object is illuminated by short pulses, or in the frequency domain, if the frequency of a monochromatic illumination is swept. The lateral variation of the dielectric constant tensor can be obtained in terms of the measured reflected field at a number of points in the vicinity of the object. How near the measurements should be conducted depends on the resolution with which the lateral variation of the dielectric constant is to be reconstructed. This is mainly due to the fact that waves with high lateral resolution decay rapidly against the distance from the object. The normal (depth-dependent) variation of the dielectric constant, on the other hand, can be reconstructed in terms of the frequency dependence of the measured scattered field via an inverse Fourier transform or equivalently in terms of the time dependent reflection coefficient, if a short duration pulse is used for illumination. This procedure is usually used to reconstruct the dielectric constant profile for planar stratified media. A new method for reconstructing the three-dimensional permittivity profile of an inhomogeneous dielectric object located within a cavity resonator is presented. It utilizes the measured frequency response of the scattering parameters associated with connecting the resonator to properly chosen coupling ports. The cavity resonator is necessary to avoid dealing with continuous spectra related to open structures. This doesn't however restrict the validity of the method as the resonator can be arbitrarily chosen. The resolution of the method is arbitrarily controllable via the choice of the number and location of the coupling ports on the one hand and the frequency range over which the scattering parameters are measured on the other hand. Application to a simple one dimensional case shows excellent agreement between originally assumed and reconstructed dielectric profiles. The presented method represents new basis for a wide class of inverse problems, e.g., filter design, microwave imaging and remote sensing.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"42 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127770019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Image contrast enhancement using homomorphic processing and adaptive filters","authors":"M. Hadhoud","doi":"10.1109/NRSC.1999.760889","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760889","url":null,"abstract":"This paper proposes a method of image enhancement using adaptive filters. An adaptive high pass (HP) and low pass (LP) filters are combined in homomorphic domain to obtain adaptive image enhancement filter. The method offers great advantages over the method of using fixed filters. Adaptive filters allow the use of HPF with different sizes and amount of sharpening as required. Also this paper proposes spatial domain contrast enhancement method which is equivalent to the processing in homomorphic domain without the need to any logarithmic operations. The use of adaptive HP method is shown to be very useful and avoids the noise amplification and details blurring. The adaptive method do not assume any knowledge about the image statistics or characteristics. Results are presented to illustrate the performance of the proposed method. Future research includes studying the use of multiple HPF channels with different HP filter sizes and the adaptation of the enhancement parameters to the changes in the image local contrast.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127919324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of cellular telephone radiation on the human head using plane waves at 900 MHz","authors":"H. Elkamchouchi","doi":"10.1109/NRSC.1999.760958","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760958","url":null,"abstract":"With the wide spread usage of cellular telephones (GSM) in Egypt, many questions have been raised about the influence of these telephones on the human body. In this research, we study the effect of transient electromagnetic fields on the human head using the finite difference time domain technique (FDTD). To develop this study, we have introduced two models for the human head, which are homogeneous and heterogeneous models. These two models have been implemented on two different grid size models, which are the fine model and coarse models in order to illustrate the effect of wavelength to grid size ratio on the accuracy of the results. Three different incident fields have been used to cover a wide band of frequencies. The electric fields inside the head models have been computed and the specific absorption rate (SAR) has also been computed for the proposed models. The SAR results of this work have been compared with international standards, which are the European standard and the ANSI/IEEE standard.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121241613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reed-Solomon codes and their performance for FCMA systems in fading satellite channel","authors":"M. Ali, A. Abou-El-azm, M. Marie","doi":"10.1109/NRSC.1999.760893","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760893","url":null,"abstract":"Fading in mobile satellite communications severely degrades the performance of data transmission. The emphasis in this paper is on the performance of uncoded and coded FCMA in the fading environment. The channel is modeled with nonfrequency selective Rice and Rayleigh fading using noncoherent demodulation with Reed-Solomon (RS) codes and hard decision decoding. Berlekamp-Massey decoding of RS codes is used to compensate for the fading. The bit error rate (BER) after decoding is calculated for specific codes and for different values of Rician channel parameters. The results of this paper are obtained by simulation techniques. They show that substantial coding gains are obtained compared to the uncoded reference system. They are also useful as a reference for validating the results of simulation studies.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123930307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The European VLBI Network, its new data processor at JIVE, and opportunities for expansion","authors":"R. Schilizzi","doi":"10.1109/NRSC.1999.760864","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760864","url":null,"abstract":"The European Very Long Baseline Interferometry Network (EVN) is in the final stages of a major revolution in its capabilities. The new capabilities include improved astronomical receiver systems, greater frequency agility and new data acquisition systems at the member telescopes, and a new 16-station VLBI data processor at the central institute for the EVN, the Joint Institute for VLBI in Europe (JIVE). The geographical distribution of telescopes in the EVN can be improved by the addition of a radio telescope in southern Egypt, the Abu Simbel Project. Its location well to the south of Europe means that this telescope would provide improved aperture plane coverage and image quality for measurements with the EVN.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"200 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115719510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and simulation of a wideband CMOS transconductance amplifier","authors":"M. Elazab","doi":"10.1109/NRSC.1999.760934","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760934","url":null,"abstract":"A CMOS wideband transconductance amplifier has been designed in 1.2 /spl mu/m technology. The output current driving capabilities as well as the frequency response have been simulated using Monte Carlo analysis in order to investigate the effect of dispersion in process parameters. The control over the amplifier bandwidth is obtained by adequate design of the main biasing current. Finally, the transfer characteristic curve nonlinearity is also studied.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128190958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aircraft recognition system using eigenvector technique","authors":"A. Somaie, A. Badr, T. Salah","doi":"10.1109/NRSC.1999.760913","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760913","url":null,"abstract":"The general task of the aircraft identification system is to select the important aspects and ignore the irrelevant data. The perimeter of the aircraft in the image plane possesses sufficient information for recognition. The contour of each aircraft was extracted using a morphological module and the perimeter was standardised in the gray level. The eigenvector technique was exploited to align the input image to a fixed orientation. The principal component analysis is used to create a new co-ordinate system for object representation where each aircraft is projected onto that plane and the projection coefficients are used for the purpose of recognition. The new features are invariant to translation, scale and rotation. The presented algorithm was tested and it was found that the recognition performance is 100% using only an x-l features where x is the number of the referenced aircraft.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125249903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate modeling of energy-dependent impact ionization rate for hydrodynamic simulators of semiconductor devices","authors":"M.H. El-Sahn","doi":"10.1109/NRSC.1999.760930","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760930","url":null,"abstract":"Proposes an accurate nonlocal model describing the impact ionization rate in semiconductor devices in terms of the carrier mean energy. The model is developed from the general set of hydrodynamic equations (HDEs) without presuming any form a priori for the carrier distribution function. A fundamental feature of the present model is that it takes into account the band structure effect on the carrier generation rate through the carrier-energy relaxation time. In order to confirm the validity of the model, it is compared with the famous empirical and analytical models. In contrary to the previous energy-dependent models, the present one does not underestimate the generation rate by impact ionization at high fields. So, it can be used for better predictions of the avalanche breakdown voltage and avalanche injection currents in semiconductor devices.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"495 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115885581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infrared image compression using subband coding in the wavelet domain","authors":"A. Ragab, A. Mohamed, M. Hamid","doi":"10.1109/NRSC.1999.760903","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760903","url":null,"abstract":"Infrared (IR) imaging has become one of the most important image sources and is used now in many different applications. Thus, the compression of IR images is very important for the transmission and storage purposes. The application of the subband coding in the wavelet domain (SCWD) to IR images is shown to be a good tool to reduce the image redundancy. In this paper, the SCWD is applied to IR images with one and two levels of decomposition and the results are compared with a standard image. The application of the SCWD to IR images gives a bit rate of 1.25 bpp with very high PSNR and excellent perceptual quality. Also, a bit rate of 0.312 bpp is obtained with high PSNR and very good perceptual quality of the reconstructed image.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"359 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115890662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Error detection and optimum decoding for line codes in digital transmission systems","authors":"A. Abou-El-azm, H. El-daim","doi":"10.1109/NRSC.1999.760919","DOIUrl":"https://doi.org/10.1109/NRSC.1999.760919","url":null,"abstract":"It is important for the communication link to detect random errors caused by noise, interference and crosstalk or caused by other impairments, so that the fault can be rectified. For this reason, error detection is a vital part of a transmission link. When errors have been detected, it is important for the decoder to minimize their effect or to ensure that they do not cause further errors. This paper introduces various methods to evaluate the performance of a digital transmission system at the receiving terminal. Optimization techniques to construct the decoding maps for line codes are also investigated. They help the designers to predict the error rate in the decoded data assuming the transmission error rate is given. The predicted error rate is based on the error extension factor for the line code. Thus, the paper presents the methodology technique to obtain this factor for most line codes. It depends on the statistics of the transmitted data and the decoding map for the code.","PeriodicalId":250544,"journal":{"name":"Proceedings of the Sixteenth National Radio Science Conference. NRSC'99 (IEEE Cat. No.99EX249)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128830301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}