Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109)最新文献_第6页

Classical active noise control technique 经典的主动噪声控制技术

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711519

A. Moustafa, N. Messiha, A. El-Malawany, M. El-Messiry, M. Shafik

{"title":"Classical active noise control technique","authors":"A. Moustafa, N. Messiha, A. El-Malawany, M. El-Messiry, M. Shafik","doi":"10.1109/NRSC.1998.711519","DOIUrl":"https://doi.org/10.1109/NRSC.1998.711519","url":null,"abstract":"A comprehensive theoretical investigation of a single input/single output (SISO) and a single input/multioutput (SIMO) active noise control system is presented. 'Classical' active noise control (CANC) where secondary sources act in antiphase with the primary noise source represents the bulk of this work. Previous studies concentrate mainly on the practical aspect of particular problems using analog devices without suggesting any algorithm that can be used to solve those problems using a PC. This was taken into consideration in the present study in which a digital model is developed and an algorithm is designed particularly to improve the noise reduction (NR) by taking into account the medium specification, the frequency response of the transducers (microphone and loudspeaker), the noise distribution and the separation distance between the sources. Two cases are studied. The first considers a single loudspeaker (SISO) and the second considers two loudspeakers (SIMO) which is known as Swinbank's source. The main results are: first, the ability for use with narrow band and wide band noise. Second, the transducers which were modeled as digital filters must have flat frequency response. Third, high degrees of noise reduction were obtained using multioutput devices. Fourth, the cancellation degree is a function of phase and amplitude for a single harmonic as well as the frequency of wide band noise. Fifth, a good noise reduction can be obtained over a long distance of the medium with accurate adjustment of the separation distance between the primary and secondary sources.","PeriodicalId":128355,"journal":{"name":"Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123036587","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}

引用次数: 1

New approach for the fault diagnosis of linear analog networks 线性模拟网络故障诊断的新方法

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711501

M. Rizk, M.Y. Yacout

引用次数: 4

Network representation of gyrotron oscillator using frequency-domain analysis 使用频域分析的回旋管振荡器网络表示

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711505

O. Abo-Elnor

引用次数: 0

Comparison of material selection methods for lead-frame package encapsulation of integrated circuits 集成电路引线框架封装材料选择方法的比较

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711516

W. Boulos, H. Ragaie, S. Sakr, N. El-Mahallawy

引用次数: 0

A novel secure image coding scheme using fractal transformation 一种新的基于分形变换的安全图像编码方案

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711485

S. El-Khamy, H. Abdou

引用次数: 7

Analysis of axial-mode helix without a ground plane 无地平面的轴向螺旋分析

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711450

S. Zainud-Deen

引用次数: 1

Efficient techniques of sampling circular aperture distributions for ring array synthesis 环形阵列合成中圆形孔径分布采样的有效技术

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711455

S. El-Khamy, A.-E.-F.A. Abou-Hashem

{"title":"Efficient techniques of sampling circular aperture distributions for ring array synthesis","authors":"S. El-Khamy, A.-E.-F.A. Abou-Hashem","doi":"10.1109/NRSC.1998.711455","DOIUrl":"https://doi.org/10.1109/NRSC.1998.711455","url":null,"abstract":"The sampling of circular apertures with continuous distributions using discrete feeding in the form of ring arrays is considered in this paper. The generally complicated continuous aperture-feeding problem is thus transformed to simply determining the array excitation coefficients. Most of previous sampling techniques were based on discretizing apertures into rectangular grids (cells). The feeding coefficient of the corresponding array element is either taken as the actual value of the corresponding continuous aperture feeding (conventional sampling (CS)) or as the average value among the cell area (integrated sampling (IS)). We have extended this technique to synthesize concentric ring arrays with special geometry with either CS or IS feeding. The rings are discretized into radial sectors each with either equal or unequal areas. The proposed techniques have some advantages over previously used ones due to the simplicity of calculating the feeding coefficients and in using fewer array elements, in general. Numerical results demonstrate that the proposed aperture sampling techniques give approximations of the required far field patterns for many types of aperture feeding including uniform, linear taper, parabolic taper and Taylor distributions. A detailed comparative study with other techniques is also presented.","PeriodicalId":128355,"journal":{"name":"Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122153944","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}

引用次数: 8

An optimum design of an ultrasonic transducer array for medical imaging 医学成像用超声换能器阵列的优化设计

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711525

S. El-sherbiny, E. Shafei

{"title":"An optimum design of an ultrasonic transducer array for medical imaging","authors":"S. El-sherbiny, E. Shafei","doi":"10.1109/NRSC.1998.711525","DOIUrl":"https://doi.org/10.1109/NRSC.1998.711525","url":null,"abstract":"In this paper, it is shown how to optimize an ultrasonic transducer array system, such that each array element receives a maximum reflected signal from that part of the object (to be imaged) which is directly lying in front of it, while it receives the minimum signal from the rest of the object. According to this concept, it is expected that the image quality will become better. Also, it is shown that the object should not lie directly in contact with the array, but it rather should be at a certain specific distance in order to get a maximum 'useful' signal. Thus if a coplanar circular receiving transducer is moved away from an identical transmitting one, it is shown that the receiving transducer passes by successive positions of maximum and minimum echoes which are induced by a flat metallic reflector situated at a predetermined specific distance. The first point of minimum echo is taken to be the optimum position for the receiving transducer when designing a transducer matrix for imaging applications. Theoretical as well as experimental results are obtained and compared with each other, and a rather fair coincidence is found between both kinds of results.","PeriodicalId":128355,"journal":{"name":"Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109)","volume":"28 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120862098","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}

引用次数: 0

Design considerations for low sidelobe levels for rectangular microstrip array antennas 矩形微带阵列天线低旁瓣电平的设计考虑

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711447

M. Alfaouri

引用次数: 1

Hybrid wavelet transform and MPEG-1 video coding system 混合小波变换与MPEG-1视频编码系统

Proceedings of the Fifteenth National Radio Science Conference. NRSC '98 (Cat. No.98EX109) Pub Date : 1998-02-24 DOI: 10.1109/NRSC.1998.711486

E. Youssef, S.E. El-Nahas, I. Ahmed, M. Moussa

引用次数: 0