{"title":"Electrostatic beneficiation of potash ores","authors":"I. Inculet, G. Strathdee","doi":"10.1109/IAS.1988.25298","DOIUrl":"https://doi.org/10.1109/IAS.1988.25298","url":null,"abstract":"A study of the effectiveness of electrostatic extraction of the KCl fraction from the potash ore by additive enhanced triboelectrification is presented. The separation process depends on adequate triboelectrification between the KaCl and NaCl fractions. The authors use reagents added to the ore and study their influence on the beneficiation effects. The experiments were carried out using a fluidized bed conveyor separator. The results show that significant KCl recovery can be achieved in a two-stage process with special pretreatment. Recoveries in the order of 50% of the total KCl mass were achieved with a KCl concentration of 92%. The dry electrostatic process looks sufficiently promising to be considered further by the potash industry. While the results point out what can be achieved industrially by this process, they also show the desirability of fundamental studies in the relatively unexplored field of additive enhanced triboelectrification.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131264064","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":"Transistor inverter optimization employing self-oscillation for low cost and simplicity","authors":"J. Ferreira, J. V. van Wyk","doi":"10.1109/IAS.1988.25177","DOIUrl":"https://doi.org/10.1109/IAS.1988.25177","url":null,"abstract":"It is shown that it is possible to extend the power range of high-frequency transistor inverters into the kilowatt region by introducing: (1) simple but effective relief of bipolar transistor switching stresses; (2) reduction and containment of transistor storage times at turn-off; and (3) effective design of the transformer and effective electromagnetic layout of the inverter. The authors first examine switching stress relief in the transistors of the inverter by previously proposed nondissipative snubbing methods, since this is a prerequisite to increasing inverter power levels. They then propose a novel nondissipative snubbing concept, which is applied to self-oscillating inverters with magnetic feedback and center-tap topology. The combined circuit is then developed further for a converter with saturation of the main transformer or saturation of the base drive transformer. This is also done for these converters in a bidirectional configuration. Enhancement of bipolar transistor turn-off and optimized electromagnetic design of the electromagnetic components and layout of the topology, which completes the development of a simple, low-cost converter configuration, are discussed.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123848562","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":"Is there a lag from input to output of a thyristor converter?","authors":"X. Ma","doi":"10.1109/IAS.1988.25185","DOIUrl":"https://doi.org/10.1109/IAS.1988.25185","url":null,"abstract":"Dynamic behavior of thyristor converters has until now been modeled using a fixed-period sampling element, assuming an approximate transport lag of T/sub 0//2. Many experiments have shown that this is longer than the actual lag, and the model needs to be revised. A variable-period sampling model is proposed. Theoretical analysis and simulation results show that the converter should be considered as a proportional element without lag.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121520080","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":"Retrofitting optical reflectors into existing fluorescent fixtures","authors":"M.F. Neils","doi":"10.1109/IAS.1988.25316","DOIUrl":"https://doi.org/10.1109/IAS.1988.25316","url":null,"abstract":"The suitability of retrofitting specular optical reflectors into existing fluorescent fixtures is discussed from an applications perspective. Of particular concern are efficiency of operation and photometric performance. Included is basic information on reflector efficiency, photometrics, lens requirements, and fixture efficiency. Comparisons are made between fixtures with and without optical reflectors. The information presented provides a review of reflector basics and techniques for their evaluation. Typical applications include offices and supermarkets.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115196020","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":"Computation of ion-flow fields of AC coronating wires by charge simulation technique","authors":"M. Abdel-Salam, D. Shamloul","doi":"10.1109/IAS.1988.25284","DOIUrl":"https://doi.org/10.1109/IAS.1988.25284","url":null,"abstract":"A method is developed to compute the ion flow from AC corona-discharging wire above the ground plane, without resort to simplifying assumptions. In this method, ions are emitted from the wire into the space around it when the surface gradient of the wire exceeds the onset value. The space charges are simulated by discrete line charges, and the C-S technique is used to compute the charge emission from the wire during corona periods over both the positive and negative half cycles. The simulation line charges are displaced away from and back to the wire by prevailing AC field with a subsequent recombination between the outgoing and returning line charges of opposite polarities. Among the parameters computed are: (1) the corona current components and their time variations during the positive and negative half-cycles; (2) the corona charge-voltage characteristics for different applied voltages; and (3) the corona onset and the ionization onset voltages as well as the corona ending voltage over the succeeding positive and negative half cycles.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129585155","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":"An on-line PC-based converter PWM modulator","authors":"D. Vincenti, P. Ziogas, R. Patel","doi":"10.1109/IAS.1988.25166","DOIUrl":"https://doi.org/10.1109/IAS.1988.25166","url":null,"abstract":"Developments in power control techniques for pulsewidth-modulated (PWM) inverters are often ignored because of lack of time for adequate testing and evaluation. The programmable PC-based PWM described is designed to alleviate this problem. The modulator is capable of generating, in ready-to-use form, gating signals for any type of PWM scheme and most types of converters. It can also generate and display associated converter-output voltage and current waveforms and their respective frequency spectra for further evaluation of selected PWM schemes. Therefore, tasks such as the selection of optimum PWM strategies, switching frequencies, and voltage/frequency curves (for variable-speed AC drives) are easier to perform. Moreover, the proposed research and development tool differs from similar devices in that it is user-friendly, multipurpose, and versatile. Selected performance features of the developed prototype are demonstrated by presenting the associated experimental waveforms.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"6 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120901649","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":"Transmission line model of base spreading resistance at high currents","authors":"H. Lin, D. J. Page, J. Ostop","doi":"10.1109/IAS.1988.25127","DOIUrl":"https://doi.org/10.1109/IAS.1988.25127","url":null,"abstract":"The base resistance of a bipolar transistor at high currents has been analyzed using a transmission-line model and taking the current-crowding effect into account. A closed-form solution has been obtained and shows that the collector current dependency on V/sub B,E/ is proportional to exp(V/sub B,E//2V/sub T/). This ideology factor of 2 for collector current is usually attributed to conductivity modulation at high currents. Analysis shows that the current crowding can also contribute to the nonunity ideology factor. The analysis is in agreement with experimental results.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"205 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116188918","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":"Computer analyses of glass forehearths","authors":"L. Chang, W. A. Poolos, F. J. Nelson","doi":"10.1109/IAS.1988.25202","DOIUrl":"https://doi.org/10.1109/IAS.1988.25202","url":null,"abstract":"A computer model, FHI, written to perform analytical mass and energy balances for glass forehearth cooling zones is discussed. Assumptions used to formulate the model are presented, together with results of a sample calculation. The interpretation and potential application of model results in control strategies are discussed.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116338304","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":"Impact of electric utility and customer modifications on existing medium voltage circuit breakers","authors":"K. R. Shah, E. R. Detjen, D. Epley","doi":"10.1109/IAS.1988.25259","DOIUrl":"https://doi.org/10.1109/IAS.1988.25259","url":null,"abstract":"The authors discuss seven factors that can increase circuit-breaker duties at existing installations and provide detailed analyses of possible corrective actions to alleviate the breaker overstressing problem, with special reference to the National Institute of Health's system. They emphasize a need for cooperation between large customers and the utility to obtain a mutually beneficial solution to the problem and prevent the recurrence of similar problems in the future.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121996651","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":"Potential and field computations by an optimized Monte Carlo technique","authors":"H. Anis, M. Abdallah","doi":"10.1109/IAS.1988.25290","DOIUrl":"https://doi.org/10.1109/IAS.1988.25290","url":null,"abstract":"The Monte Carlo method is applied to diverging field problems. The computational effort, expressed by the number of steps in random walks, is related to the relative space potential, the prespecified walk termination distance, and the degree of field nonuniformity in the gap. To obtain potential and field distributions in a given system, equations for these quantities are developed at neighboring space points using Green's function. The accuracy of the algorithm is markedly enhanced by seeking the optimal spacing of the neighboring points. The technique compares satisfactorily with the charge-simulation method in a case study on a hemispherically capped rod-plane gap.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126977710","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}