Pub Date : 1994-03-29DOI: 10.1109/SOUTHC.1994.498076
P. Myllymaki, H. Tirri
Given a set of samples of a probability distribution on a set of discrete random variables, we study the problem of constructing a good approximate neural network model of the underlying probability distribution. Our approach is based on an unsupervised learning scheme where the samples are first divided into separate clusters, and each cluster is then coded as a single vector. These Bayesian prototype vectors consist of conditional probabilities representing the attribute-value distribution inside the corresponding cluster. Using these prototype vectors, it is possible to model the underlying joint probability distribution as a simple Bayesian network (a tree), which can be realized as a feedforward neural network capable of probabilistic reasoning. We describe how the prototypes can be determined, given a partition of the samples, and present a method for evaluating the likelihood of the corresponding Bayesian tree. We also present a greedy heuristic for searching through the space of different partition schemes with different numbers of clusters, aiming at an optimal approximation of the probability distribution.
{"title":"Learning in neural networks with Bayesian prototypes","authors":"P. Myllymaki, H. Tirri","doi":"10.1109/SOUTHC.1994.498076","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498076","url":null,"abstract":"Given a set of samples of a probability distribution on a set of discrete random variables, we study the problem of constructing a good approximate neural network model of the underlying probability distribution. Our approach is based on an unsupervised learning scheme where the samples are first divided into separate clusters, and each cluster is then coded as a single vector. These Bayesian prototype vectors consist of conditional probabilities representing the attribute-value distribution inside the corresponding cluster. Using these prototype vectors, it is possible to model the underlying joint probability distribution as a simple Bayesian network (a tree), which can be realized as a feedforward neural network capable of probabilistic reasoning. We describe how the prototypes can be determined, given a partition of the samples, and present a method for evaluating the likelihood of the corresponding Bayesian tree. We also present a greedy heuristic for searching through the space of different partition schemes with different numbers of clusters, aiming at an optimal approximation of the probability distribution.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131635856","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498110
J. Vinson
Presents one technique to apply concurrent engineering in the development of a reliable fuse element in CMOS PROMs. The development required both a new circuit and process design. The five stages presented were used to produce a reliable fuse element that is also manufacturable. The use of these techniques uncovered several limitations in the circuit early enough in the development to be corrected. One reported in this paper was the poor current gain of the fusing bipolar transistor.
{"title":"NiCr fuse reliability-a new approach","authors":"J. Vinson","doi":"10.1109/SOUTHC.1994.498110","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498110","url":null,"abstract":"Presents one technique to apply concurrent engineering in the development of a reliable fuse element in CMOS PROMs. The development required both a new circuit and process design. The five stages presented were used to produce a reliable fuse element that is also manufacturable. The use of these techniques uncovered several limitations in the circuit early enough in the development to be corrected. One reported in this paper was the poor current gain of the fusing bipolar transistor.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129697103","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498138
C. Melear
Inverting power supplies and high voltage/current switches form the basis for many uninterruptible power supply (UPS) designs. In a very basic sense, a 60 Hz square wave with minimal filtering may suffice in many applications. Not only is power quality a factor but so is the speed at which a UPS can be brought online. As the need for quality power increases and response times to switch in the UPS decrease, more sophisticated controllers for UPSs must be used. Microcontrollers, such as the MC68F333, provide an excellent vehicle to implement intelligent UPS systems. The MCU can provide the intelligence and the peripheral modules to measure and monitor external voltage levels and frequency. From this information intelligent decisions can be made on whether to enable a power conditioning circuit or to completely switch over to a UPS until the main source of power has been restored. Microcontrollers, because of the inherent ability to generate complex, high speed timing signals that can be phase and frequency locked together, makes these devices a natural choice when designing modern UPSs. These MCU-based designs allow for higher PWM switching speeds, better monitoring of the external line voltage and enhanced ability to determine what type of malfunction is occurring when trouble happens. From this information MCU based UPSs can be built to economically provide back-up power when warranted by external conditions.
{"title":"An MCU based uninterruptible power supply using an MC68F333","authors":"C. Melear","doi":"10.1109/SOUTHC.1994.498138","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498138","url":null,"abstract":"Inverting power supplies and high voltage/current switches form the basis for many uninterruptible power supply (UPS) designs. In a very basic sense, a 60 Hz square wave with minimal filtering may suffice in many applications. Not only is power quality a factor but so is the speed at which a UPS can be brought online. As the need for quality power increases and response times to switch in the UPS decrease, more sophisticated controllers for UPSs must be used. Microcontrollers, such as the MC68F333, provide an excellent vehicle to implement intelligent UPS systems. The MCU can provide the intelligence and the peripheral modules to measure and monitor external voltage levels and frequency. From this information intelligent decisions can be made on whether to enable a power conditioning circuit or to completely switch over to a UPS until the main source of power has been restored. Microcontrollers, because of the inherent ability to generate complex, high speed timing signals that can be phase and frequency locked together, makes these devices a natural choice when designing modern UPSs. These MCU-based designs allow for higher PWM switching speeds, better monitoring of the external line voltage and enhanced ability to determine what type of malfunction is occurring when trouble happens. From this information MCU based UPSs can be built to economically provide back-up power when warranted by external conditions.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129487030","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498071
J. Jacobs
When electric vehicles are discussed with the public, two questions inevitably arise: how far can it go between charges, and how fast can it go? Both of these issues are related in part to the electrical energy stored and the efficiency of conversion from electrical energy to mechanical energy. In practical use many electric vehicle drivers have been known to use only 10-20% of the vehicle's range before recharging. The desire not to run out of enough energy to return to a charging station motivates the drivers to be very conservative. One solution to this problem is to equip the vehicle with an auxiliary power supply which will recharge the batteries. Such vehicles are powered by a combination of stored electric energy and chemical fuel. Here, the author describes these so-called hybrid vehicles.
{"title":"Range extension for electric vehicles","authors":"J. Jacobs","doi":"10.1109/SOUTHC.1994.498071","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498071","url":null,"abstract":"When electric vehicles are discussed with the public, two questions inevitably arise: how far can it go between charges, and how fast can it go? Both of these issues are related in part to the electrical energy stored and the efficiency of conversion from electrical energy to mechanical energy. In practical use many electric vehicle drivers have been known to use only 10-20% of the vehicle's range before recharging. The desire not to run out of enough energy to return to a charging station motivates the drivers to be very conservative. One solution to this problem is to equip the vehicle with an auxiliary power supply which will recharge the batteries. Such vehicles are powered by a combination of stored electric energy and chemical fuel. Here, the author describes these so-called hybrid vehicles.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114293180","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498094
H. Latchman, O. Crisalle
In this paper we develop a stability criterion for systems with uncertainties which are manifested in the frequency domain by simply-connected and closed, arbitrary uncertainty regions which satisfy a mild convexity constraint. In particular, well-known stability results for the case of disk-bounded frequency domain uncertainties are recovered as a special case of the proposed approach. The main results hinge on the definition of the critical direction as the direction of the line joining the -1+j0 point to the the nominal frequency response at a particular frequency. It is argued that the worst case uncertainties must lie along this line and this idea is exploited to yield a general stability criterion. An example arising from system and uncertainty identification is presented to illustrate the ideas developed in the paper. An application of the results of this paper yields exact and explicit formulae for the robust stability of systems with ellipsoidal parametric uncertainties.
{"title":"Exact Nyquist-like stability results for ellipsoidal uncertainties","authors":"H. Latchman, O. Crisalle","doi":"10.1109/SOUTHC.1994.498094","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498094","url":null,"abstract":"In this paper we develop a stability criterion for systems with uncertainties which are manifested in the frequency domain by simply-connected and closed, arbitrary uncertainty regions which satisfy a mild convexity constraint. In particular, well-known stability results for the case of disk-bounded frequency domain uncertainties are recovered as a special case of the proposed approach. The main results hinge on the definition of the critical direction as the direction of the line joining the -1+j0 point to the the nominal frequency response at a particular frequency. It is argued that the worst case uncertainties must lie along this line and this idea is exploited to yield a general stability criterion. An example arising from system and uncertainty identification is presented to illustrate the ideas developed in the paper. An application of the results of this paper yields exact and explicit formulae for the robust stability of systems with ellipsoidal parametric uncertainties.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121733818","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498136
L. Tillis, C.W. Williams
Florida Power Corporation (USA) received complaints from an electronic components manufacturer regarding poor power quality at their facility outside of Orlando, Florida. Electrical disturbances were occurring which resulted in motors or systems shutting down and a consequent loss of production. This paper describes the procedure used to determine the cause of the problem and how the problem was mitigated.
{"title":"Voltage sag investigation and mitigation in an electronics manufacturing plant","authors":"L. Tillis, C.W. Williams","doi":"10.1109/SOUTHC.1994.498136","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498136","url":null,"abstract":"Florida Power Corporation (USA) received complaints from an electronic components manufacturer regarding poor power quality at their facility outside of Orlando, Florida. Electrical disturbances were occurring which resulted in motors or systems shutting down and a consequent loss of production. This paper describes the procedure used to determine the cause of the problem and how the problem was mitigated.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117090101","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498098
P. Lewis
Uncertainty in the job market in recent years has been driven by a redirection of national priorities and rapid advances in technology. While it is hoped the decrease in military tensions among nations will contribute to more stability worldwide, we will undoubtedly experience an increase in economic tension as nations compete for a larger share of expanding world markets. Engineers, through their formal education, critical thinking and problem solving skills are positioned to make major contributions to this new era of productivity. However, to remain a contributing part of this global economic expansion, engineers must not only constantly enhance their knowledge of technology. They must also learn about their customers, those individuals who use the products being designed. Continuing education will play an important part in preparing engineers for future employment.
{"title":"Continuing education in an age of uncertainty","authors":"P. Lewis","doi":"10.1109/SOUTHC.1994.498098","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498098","url":null,"abstract":"Uncertainty in the job market in recent years has been driven by a redirection of national priorities and rapid advances in technology. While it is hoped the decrease in military tensions among nations will contribute to more stability worldwide, we will undoubtedly experience an increase in economic tension as nations compete for a larger share of expanding world markets. Engineers, through their formal education, critical thinking and problem solving skills are positioned to make major contributions to this new era of productivity. However, to remain a contributing part of this global economic expansion, engineers must not only constantly enhance their knowledge of technology. They must also learn about their customers, those individuals who use the products being designed. Continuing education will play an important part in preparing engineers for future employment.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134091359","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498106
D. S. Dunn, M. Telep, E. P. Augustin
This paper describes a ferrite antenna that can produce any polarization on the Poincare sphere over the frequency range of 9.0 to 11.4 GHz by utilizing Faraday rotation and a quarter-wavelength phase shifter. All possible polarizations of the electromagnetic wave are achievable with this antenna which includes linear, circular and elliptical polarizations. Any tilt angle of elliptical polarization and any orientation of the linear polarization can be achieved as well. The polarization of the ferrite antenna can be electronically switched to a different polarization instantly without the use of moving parts. An automatic data acquisition system was designed and built to fully analyze the antenna's characteristics. Measured data shows cross-polarization values of 35 dB, axial ratios less than 1.5 dB and VSWR<2.0:1.
{"title":"A variable polarization ferrite antenna","authors":"D. S. Dunn, M. Telep, E. P. Augustin","doi":"10.1109/SOUTHC.1994.498106","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498106","url":null,"abstract":"This paper describes a ferrite antenna that can produce any polarization on the Poincare sphere over the frequency range of 9.0 to 11.4 GHz by utilizing Faraday rotation and a quarter-wavelength phase shifter. All possible polarizations of the electromagnetic wave are achievable with this antenna which includes linear, circular and elliptical polarizations. Any tilt angle of elliptical polarization and any orientation of the linear polarization can be achieved as well. The polarization of the ferrite antenna can be electronically switched to a different polarization instantly without the use of moving parts. An automatic data acquisition system was designed and built to fully analyze the antenna's characteristics. Measured data shows cross-polarization values of 35 dB, axial ratios less than 1.5 dB and VSWR<2.0:1.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132111910","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498113
W. Wong, M. S. Shekar
A SPICE model for the MOS-gated Emitter Switched Thyristor (EST) structure is developed for the first time. This static model is based on analytical models developed through two-dimensional numerical simulations using PISCES. Using this model the complete static characteristics of the EST, including the IGBT region of operation can be described. The EST model implemented in SPICE shows good agreement between the model and measurements (600 V EST) for the forward voltage drop and the main thyristor latching current density as a function of the gate bias.
首次建立了mos门控发射极开关晶闸管(EST)结构的SPICE模型。这个静态模型是基于使用双鱼座进行二维数值模拟开发的分析模型。利用该模型可以描述EST的完整静态特性，包括IGBT运行区域。在SPICE中实现的EST模型显示，模型与测量值(600 V EST)之间的正向压降和主晶闸管锁存电流密度作为栅极偏置的函数具有良好的一致性。
{"title":"SPICE modeling of the emitter switched thyristor","authors":"W. Wong, M. S. Shekar","doi":"10.1109/SOUTHC.1994.498113","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498113","url":null,"abstract":"A SPICE model for the MOS-gated Emitter Switched Thyristor (EST) structure is developed for the first time. This static model is based on analytical models developed through two-dimensional numerical simulations using PISCES. Using this model the complete static characteristics of the EST, including the IGBT region of operation can be described. The EST model implemented in SPICE shows good agreement between the model and measurements (600 V EST) for the forward voltage drop and the main thyristor latching current density as a function of the gate bias.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128189782","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 : 1994-03-29DOI: 10.1109/SOUTHC.1994.498103
T. Hentea
Purdue University Calumet is a community based university located in an urban environment (greater Chicagoland region). It proclaimed itself a "partnership University", a university that promotes strong ties with the surrounding community, its institutions, and businesses. The administration of the University is very supportive of the continuing education activities and stresses the importance of courses for professional training that enhance the competitiveness of Indiana businesses and enterprises. The university has established a resource center for small business development and created excellent special facilities for continuing education and outreach activities. This paper describes experience in developing three continuing education courses. This experience spans a six year period. It is ongoing, and it the intention to invest more time and effort in this type of activity in the next few years.
{"title":"Case studies in developing and teaching continuing education courses at a university","authors":"T. Hentea","doi":"10.1109/SOUTHC.1994.498103","DOIUrl":"https://doi.org/10.1109/SOUTHC.1994.498103","url":null,"abstract":"Purdue University Calumet is a community based university located in an urban environment (greater Chicagoland region). It proclaimed itself a \"partnership University\", a university that promotes strong ties with the surrounding community, its institutions, and businesses. The administration of the University is very supportive of the continuing education activities and stresses the importance of courses for professional training that enhance the competitiveness of Indiana businesses and enterprises. The university has established a resource center for small business development and created excellent special facilities for continuing education and outreach activities. This paper describes experience in developing three continuing education courses. This experience spans a six year period. It is ongoing, and it the intention to invest more time and effort in this type of activity in the next few years.","PeriodicalId":164672,"journal":{"name":"Conference Record Southcon","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133449741","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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