Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324304
G. A. Ford, C. Doreswamy, P. Bassapa
Spacecraft power systems are subjected to extremely hostile environments, due to the action of space plasma, temperature cycling and atomic oxygen. Literature indicates that the resistivity is sensitive to ambient temperature and pressure. The resistivity is an index which can indicate the performance of space based electrical systems. Hence, there is a need for experiments to determine the variation of leakage resistance with temperature and pressure. The surface leakage resistance, and volume resistance of Kapton H and V and Mylar films of 2 mils and 5 mils thickness were determined. The leakage resistance measurements were made according to ASTM D257. The experiments were conducted in a vacuum chamber with electrode temperatures ranging from 27/spl deg/ Centigrade to 140/spl deg/ Centigrade, and pressures varying from atmospheric to 10 millitorr at a voltage of 500 V.<>
{"title":"An investigation of the variation of leakage resistance of electrical insulating materials used on spacecraft power systems","authors":"G. A. Ford, C. Doreswamy, P. Bassapa","doi":"10.1109/SECON.1994.324304","DOIUrl":"https://doi.org/10.1109/SECON.1994.324304","url":null,"abstract":"Spacecraft power systems are subjected to extremely hostile environments, due to the action of space plasma, temperature cycling and atomic oxygen. Literature indicates that the resistivity is sensitive to ambient temperature and pressure. The resistivity is an index which can indicate the performance of space based electrical systems. Hence, there is a need for experiments to determine the variation of leakage resistance with temperature and pressure. The surface leakage resistance, and volume resistance of Kapton H and V and Mylar films of 2 mils and 5 mils thickness were determined. The leakage resistance measurements were made according to ASTM D257. The experiments were conducted in a vacuum chamber with electrode temperatures ranging from 27/spl deg/ Centigrade to 140/spl deg/ Centigrade, and pressures varying from atmospheric to 10 millitorr at a voltage of 500 V.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116620662","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324329
P. Liu, L. Martinez
Two new mapping methods for implementing neural networks on parallel mesh-connected processors are given. These are the rectangular region based mapping method and the no zero weight value mapping method. Implementation and performance comparisons with another existing method are carried out. One of these three methods can be used depending on system and problem parameters.<>
{"title":"Partitioned schemes of mapping neural networks onto mesh connected computers","authors":"P. Liu, L. Martinez","doi":"10.1109/SECON.1994.324329","DOIUrl":"https://doi.org/10.1109/SECON.1994.324329","url":null,"abstract":"Two new mapping methods for implementing neural networks on parallel mesh-connected processors are given. These are the rectangular region based mapping method and the no zero weight value mapping method. Implementation and performance comparisons with another existing method are carried out. One of these three methods can be used depending on system and problem parameters.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131074704","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324344
E. Ososanya, M. McGlone, T. D. Strong
Modern computer systems often are designed around a bus architecture. This, of course eliminates the need for complete point-to-point interconnection of all the devices attached to the bus. The major hurdle to this system is in resolving the conflicts that arise when more than one device wants to use the bus to communicate at a time. The job of resolving such conflicts is left to bus arbitration circuitry. A system designer using the MC68000 family is in some luck. This series of microprocessors has a limited set of lines built in to allow for external circuitry to request and receive the bus from the processor. However, having given up the bus the processor does nothing to decide who receives the bus next. This is left to external arbitration circuitry. This paper describes a VLSI chip designed to perform bus arbitration for the Motorola MC68000 series of microprocessors. With such a module, several devices (such as DMA, I/O controllers, and multiple microprocessors) can share a single bus while our device handles all bus conflicts using a priority scheme. The device is flexible, programmable, and compatible with the MC68000 family's bus architecture and their support chips.<>
{"title":"VLSI design of a bus arbitration module for the 68000 series of microprocessors","authors":"E. Ososanya, M. McGlone, T. D. Strong","doi":"10.1109/SECON.1994.324344","DOIUrl":"https://doi.org/10.1109/SECON.1994.324344","url":null,"abstract":"Modern computer systems often are designed around a bus architecture. This, of course eliminates the need for complete point-to-point interconnection of all the devices attached to the bus. The major hurdle to this system is in resolving the conflicts that arise when more than one device wants to use the bus to communicate at a time. The job of resolving such conflicts is left to bus arbitration circuitry. A system designer using the MC68000 family is in some luck. This series of microprocessors has a limited set of lines built in to allow for external circuitry to request and receive the bus from the processor. However, having given up the bus the processor does nothing to decide who receives the bus next. This is left to external arbitration circuitry. This paper describes a VLSI chip designed to perform bus arbitration for the Motorola MC68000 series of microprocessors. With such a module, several devices (such as DMA, I/O controllers, and multiple microprocessors) can share a single bus while our device handles all bus conflicts using a priority scheme. The device is flexible, programmable, and compatible with the MC68000 family's bus architecture and their support chips.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125424847","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324324
L.C. Origa de Oliveira, R.U. Pennafiel
Teaching a course of special electric loads in a continuing education program to power engineers is a difficult task because they are not familiarized with switching topology circuits. Normally, in a typical program, many hours are dedicated to explain the thyristors switching sequence and to draw the power converter currents and terminal voltages waveforms for different operative conditions. This work presents teaching support software in order to optimize the time spent in this task and, mainly, to benefit the assimilation of the proposed subjects, studying the static power converter under different nonideal operative conditions.<>
{"title":"Static converter: didactic support software","authors":"L.C. Origa de Oliveira, R.U. Pennafiel","doi":"10.1109/SECON.1994.324324","DOIUrl":"https://doi.org/10.1109/SECON.1994.324324","url":null,"abstract":"Teaching a course of special electric loads in a continuing education program to power engineers is a difficult task because they are not familiarized with switching topology circuits. Normally, in a typical program, many hours are dedicated to explain the thyristors switching sequence and to draw the power converter currents and terminal voltages waveforms for different operative conditions. This work presents teaching support software in order to optimize the time spent in this task and, mainly, to benefit the assimilation of the proposed subjects, studying the static power converter under different nonideal operative conditions.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122113896","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324295
R. Sannegowda, V. Aalo
Closed form results for the symbol error probabilities are derived for M-ary, L branch selection diversity system in a Nakagami fading environment using noncoherent frequency-shift keying modulation. The maximum SNR selection and the maximum output selection schemes are considered. The analysis is not limited to integer values of the Nakagami fading parameter m. Results for the Rayleigh fading channel are obtained and presented as special cases of those of the Nakagami fading model. The symbol error probability when the diversity branches undergo different fading statistics with unequal mean SNR are considered for the maximum SNR selection scheme. Outage probabilities are also calculated for the maximum SNR selection scheme.<>
{"title":"Performance of selection diversity systems in a Nakagami fading environment","authors":"R. Sannegowda, V. Aalo","doi":"10.1109/SECON.1994.324295","DOIUrl":"https://doi.org/10.1109/SECON.1994.324295","url":null,"abstract":"Closed form results for the symbol error probabilities are derived for M-ary, L branch selection diversity system in a Nakagami fading environment using noncoherent frequency-shift keying modulation. The maximum SNR selection and the maximum output selection schemes are considered. The analysis is not limited to integer values of the Nakagami fading parameter m. Results for the Rayleigh fading channel are obtained and presented as special cases of those of the Nakagami fading model. The symbol error probability when the diversity branches undergo different fading statistics with unequal mean SNR are considered for the maximum SNR selection scheme. Outage probabilities are also calculated for the maximum SNR selection scheme.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"27 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123578310","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324355
R. Chennupati, M. Cheng
An approach based on the physical evolution of the distribution function in the energy relaxation scale is used to study multi-valley distribution functions of electrons in GaAs subjected to a rapid change in electric field. This approach, which assumes the distribution can be determined by mean energy, is able to describe transport phenomena, including inter-valley transitions, in the scale as small as the energy relaxation time. Results show that, near the peak of velocity overshoot and bottom of undershoot in the /spl Gamma/ valley, the energy-dependent distribution cannot respond as fast as the distribution obtained from Monte Carlo method. This results in less pronounced overshoot and undershoot in the /spl Gamma/ valley when using the introduced approach than using the Monte Carlo method. However, in the L valley, overshoot and undershoot are not pronounced, and these two approaches are in very good agreement.<>
{"title":"Evolution of multi-valley electron distributions in GaAs","authors":"R. Chennupati, M. Cheng","doi":"10.1109/SECON.1994.324355","DOIUrl":"https://doi.org/10.1109/SECON.1994.324355","url":null,"abstract":"An approach based on the physical evolution of the distribution function in the energy relaxation scale is used to study multi-valley distribution functions of electrons in GaAs subjected to a rapid change in electric field. This approach, which assumes the distribution can be determined by mean energy, is able to describe transport phenomena, including inter-valley transitions, in the scale as small as the energy relaxation time. Results show that, near the peak of velocity overshoot and bottom of undershoot in the /spl Gamma/ valley, the energy-dependent distribution cannot respond as fast as the distribution obtained from Monte Carlo method. This results in less pronounced overshoot and undershoot in the /spl Gamma/ valley when using the introduced approach than using the Monte Carlo method. However, in the L valley, overshoot and undershoot are not pronounced, and these two approaches are in very good agreement.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"145 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132994219","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324278
R. Samudio, P. Pillay
The paper describes the design of a DSP-based control of a switched reluctance motor. A TMS320E15 Digital Signal Processor is used to control the conduction angle for each phase as well as the phase current. The conduction for each phase is synchronized with the rotor position by using an optical encoder shaft position sensor. Stator current control is achieved using a hysteresis current controller. Schematics and practical measurements are provided.<>
{"title":"DSP based control of switched reluctance motors","authors":"R. Samudio, P. Pillay","doi":"10.1109/SECON.1994.324278","DOIUrl":"https://doi.org/10.1109/SECON.1994.324278","url":null,"abstract":"The paper describes the design of a DSP-based control of a switched reluctance motor. A TMS320E15 Digital Signal Processor is used to control the conduction angle for each phase as well as the phase current. The conduction for each phase is synchronized with the rotor position by using an optical encoder shaft position sensor. Stator current control is achieved using a hysteresis current controller. Schematics and practical measurements are provided.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"322 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132387134","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324353
G. T. Troskey
IBM recently announced its PS/2 Server 95 based on the Pentium microprocessor. This paper provides a technical description of the product's architecture and technology. It then goes beyond that to also describe some of the nontechnical issues that were involved in the concept, design and development stages of the project. It is asserted that companies are world-class to the degree that they master all of the critical success factors, both technical and business.<>
IBM最近发布了基于Pentium微处理器的PS/2 Server 95。本文对该产品的体系结构和技术进行了技术描述。除此之外，它还描述了一些涉及项目概念、设计和开发阶段的非技术问题。有人断言，世界级的公司取决于它们掌握了所有成功的关键因素，无论是技术上的还是商业上的。
{"title":"Management and technical issues in a Pentium-based server development project","authors":"G. T. Troskey","doi":"10.1109/SECON.1994.324353","DOIUrl":"https://doi.org/10.1109/SECON.1994.324353","url":null,"abstract":"IBM recently announced its PS/2 Server 95 based on the Pentium microprocessor. This paper provides a technical description of the product's architecture and technology. It then goes beyond that to also describe some of the nontechnical issues that were involved in the concept, design and development stages of the project. It is asserted that companies are world-class to the degree that they master all of the critical success factors, both technical and business.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133848901","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324337
J. Campos, T. Kasparis
Texture is an important characteristic in an image, and it is used to identify objects or regions of interest within an image. The problem of texture classification has been widely studied and most of the proposed techniques fall into two categories: statistical or structural. In this paper, a structural approach based on the Hough method for line detection is proposed for the description of periodic textures that consist of mostly straight lines. The features used for the classification procedure are based on the relative orientations and separations of lines. With the proper normalizations, classification is independent of geometrical transformations such as rotation, translation and/or scaling. This approach provides more unique features compared to other approaches. Experimental results with test patterns are presented.<>
{"title":"Classification of periodic patterns using Hough transform","authors":"J. Campos, T. Kasparis","doi":"10.1109/SECON.1994.324337","DOIUrl":"https://doi.org/10.1109/SECON.1994.324337","url":null,"abstract":"Texture is an important characteristic in an image, and it is used to identify objects or regions of interest within an image. The problem of texture classification has been widely studied and most of the proposed techniques fall into two categories: statistical or structural. In this paper, a structural approach based on the Hough method for line detection is proposed for the description of periodic textures that consist of mostly straight lines. The features used for the classification procedure are based on the relative orientations and separations of lines. With the proper normalizations, classification is independent of geometrical transformations such as rotation, translation and/or scaling. This approach provides more unique features compared to other approaches. Experimental results with test patterns are presented.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131175052","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}
Pub Date : 1994-04-10DOI: 10.1109/SECON.1994.324297
J. Bagby
A full-wave spectral-domain integral equation formulation is used to analyze coupled open boundary microstrip transmission lines. A general rigorous formulation is specialized to the case of two identical uniform lines and a method of moments (MOM) solution is implemented. In contrast with earlier subdomain basis MOM solutions, entire-domain basis functions which incorporate appropriate edge conditions for transverse and longitudinal current components are utilized. This allows closed-term evaluation of relevant spatial integrals and results in improved accuracy using far fewer terms. Extensions of earlier results, including characteristic impedances, propagation constants and current distributions are presented for the dominant and first two higher-order coupled modes, and compare favorably to results of other techniques.<>
{"title":"Spectral domain analysis of coupled microstrip transmission lines","authors":"J. Bagby","doi":"10.1109/SECON.1994.324297","DOIUrl":"https://doi.org/10.1109/SECON.1994.324297","url":null,"abstract":"A full-wave spectral-domain integral equation formulation is used to analyze coupled open boundary microstrip transmission lines. A general rigorous formulation is specialized to the case of two identical uniform lines and a method of moments (MOM) solution is implemented. In contrast with earlier subdomain basis MOM solutions, entire-domain basis functions which incorporate appropriate edge conditions for transverse and longitudinal current components are utilized. This allows closed-term evaluation of relevant spatial integrals and results in improved accuracy using far fewer terms. Extensions of earlier results, including characteristic impedances, propagation constants and current distributions are presented for the dominant and first two higher-order coupled modes, and compare favorably to results of other techniques.<<ETX>>","PeriodicalId":119615,"journal":{"name":"Proceedings of SOUTHEASTCON '94","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131622892","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}
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