Pub Date : 1989-10-15DOI: 10.1109/INTLEC.1989.88244
D. J. Becker
A rectifier design is presented which incorporates a high-frequency conversion technology known as a quasi-resonant zero-current switcher. The power structure of this technology has been developed to allow very high speed operation; in this case the top end conversion frequency is 1 MHz. The zero-current switch technology substantially reduces switching losses in the primary switch of the circuit as well as reducing EMI (electromagnetic interference) generated in the switching process by controlling the di/dt of the system. This is accomplished by creating a resonant circuit that maintains a sinewave shape in the primary circuit. The actual operation of the primary switch is synchronized to the current waveform so that the simultaneous presence of voltage and current is permitted in the primary switch. The actual rectifier design consists of a series of conversion 'cells' operated in parallel and optimized for thermal and electrical performance. The cell groupings are then formed into a single 6 A rectifier module. This module is designed as part of a redundant rectifier system. An example would be a two-card system which would provide either 12 A or a redundant 6 A. The rectifier modules are designed for 'hot' replacement while on-line.<>
{"title":"A modular rectifier system with 1 MHz conversion frequency","authors":"D. J. Becker","doi":"10.1109/INTLEC.1989.88244","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88244","url":null,"abstract":"A rectifier design is presented which incorporates a high-frequency conversion technology known as a quasi-resonant zero-current switcher. The power structure of this technology has been developed to allow very high speed operation; in this case the top end conversion frequency is 1 MHz. The zero-current switch technology substantially reduces switching losses in the primary switch of the circuit as well as reducing EMI (electromagnetic interference) generated in the switching process by controlling the di/dt of the system. This is accomplished by creating a resonant circuit that maintains a sinewave shape in the primary circuit. The actual operation of the primary switch is synchronized to the current waveform so that the simultaneous presence of voltage and current is permitted in the primary switch. The actual rectifier design consists of a series of conversion 'cells' operated in parallel and optimized for thermal and electrical performance. The cell groupings are then formed into a single 6 A rectifier module. This module is designed as part of a redundant rectifier system. An example would be a two-card system which would provide either 12 A or a redundant 6 A. The rectifier modules are designed for 'hot' replacement while on-line.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131829388","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88283
D. Chapman
A small 1.5 kW off-line switch-mode rectifier has been developed for use in 48 V or 24 V rack power systems. The convection cooled rectifier is only 143 mm wide, 260 mm high, and 250 mm deep, and weighs only 6 kg. Two-thirds of the rectifier volume is heatsink. This has been achieved by using relatively high switching frequencies, 200 to 450 kHz for the main isolating converter and 70 kHz for the sinewave input current boost converter. Sinewave input current maximizes the use of standby generator capacity and minimizes main noise injection into the telecommunication network. The switch-mode components are housed on one printed circuit board, allowing easy access to all componentry for service. All user-required adjustments are accessible via holes through the rectifier front panel and can be adjusted without removing the rectifier from the rack.<>
{"title":"A compact 1.5 kW resonant switchmode rectifier","authors":"D. Chapman","doi":"10.1109/INTLEC.1989.88283","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88283","url":null,"abstract":"A small 1.5 kW off-line switch-mode rectifier has been developed for use in 48 V or 24 V rack power systems. The convection cooled rectifier is only 143 mm wide, 260 mm high, and 250 mm deep, and weighs only 6 kg. Two-thirds of the rectifier volume is heatsink. This has been achieved by using relatively high switching frequencies, 200 to 450 kHz for the main isolating converter and 70 kHz for the sinewave input current boost converter. Sinewave input current maximizes the use of standby generator capacity and minimizes main noise injection into the telecommunication network. The switch-mode components are housed on one printed circuit board, allowing easy access to all componentry for service. All user-required adjustments are accessible via holes through the rectifier front panel and can be adjusted without removing the rectifier from the rack.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"287 1-2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131804327","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88302
K. Boettger
In the larger present-day UPS (uninterruptible power supply) systems, the DC voltage lies in the region of 400 V. In such cases, transformation of mains AC voltages of 3*380 V to 3*440 V will not be necessary. DC rectification equipment of such UPS devices is therefore designed without any rectifier transformers. The advantages presented by this concept are smaller dimensions and weights, smaller losses, and lower costs. Safety aspects in such devices require the same safety precautions as do normal AC systems. Special attention must be paid to all possible faults in the DC circuit. The possibility of short-circuit to earth must be countered by additional monitoring and shut-down facilities. In the event of earthing of the neutral line in the AC system, the battery voltage will have superimposed on it an alternating voltage which will prohibit the earthing of the battery mid-point. This superimposed AC potential will change along with the phase control angle imposed on the rectifier set. Because of these superimposed potentials, alternating voltages may be transmitted capacitively to metal battery-stand frames, which may cause noticeable electrification on being touched. Typical values and corrective measures are described and discussed.<>
{"title":"UPS DC intermediate circuits without AC line separation","authors":"K. Boettger","doi":"10.1109/INTLEC.1989.88302","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88302","url":null,"abstract":"In the larger present-day UPS (uninterruptible power supply) systems, the DC voltage lies in the region of 400 V. In such cases, transformation of mains AC voltages of 3*380 V to 3*440 V will not be necessary. DC rectification equipment of such UPS devices is therefore designed without any rectifier transformers. The advantages presented by this concept are smaller dimensions and weights, smaller losses, and lower costs. Safety aspects in such devices require the same safety precautions as do normal AC systems. Special attention must be paid to all possible faults in the DC circuit. The possibility of short-circuit to earth must be countered by additional monitoring and shut-down facilities. In the event of earthing of the neutral line in the AC system, the battery voltage will have superimposed on it an alternating voltage which will prohibit the earthing of the battery mid-point. This superimposed AC potential will change along with the phase control angle imposed on the rectifier set. Because of these superimposed potentials, alternating voltages may be transmitted capacitively to metal battery-stand frames, which may cause noticeable electrification on being touched. Typical values and corrective measures are described and discussed.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116894299","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88243
M. E. Jacobs
Cooling with forced air is analyzed from a general perspective. It is demonstrated that there are physical processes that limit the maximum dissipation of heat from a frame or shelf of electronic equipment. These constraints are shown to arise from the limitations on allowable acoustic noise. Some results from fluid mechanics are used to construct a pressure-flow model of heat removal. Two problems of determining maximum heat dissipation are then described. In the first, the maximum dissipation in a fan-cooled shelf is derived subject to an acoustic noise constraint. In the second problem, a shelf of circuit cards is examined for which the pressure drop is already given. For this case the maximum dissipation is derived and shown to be proportional to the square-root of pressure and to the top area of the shelf. It is noted that both of these results are essential in designing new system and in specifying high-dissipation elements such as power supplies.<>
{"title":"The practical limits of forced-air cooling of electronic equipment","authors":"M. E. Jacobs","doi":"10.1109/INTLEC.1989.88243","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88243","url":null,"abstract":"Cooling with forced air is analyzed from a general perspective. It is demonstrated that there are physical processes that limit the maximum dissipation of heat from a frame or shelf of electronic equipment. These constraints are shown to arise from the limitations on allowable acoustic noise. Some results from fluid mechanics are used to construct a pressure-flow model of heat removal. Two problems of determining maximum heat dissipation are then described. In the first, the maximum dissipation in a fan-cooled shelf is derived subject to an acoustic noise constraint. In the second problem, a shelf of circuit cards is examined for which the pressure drop is already given. For this case the maximum dissipation is derived and shown to be proportional to the square-root of pressure and to the top area of the shelf. It is noted that both of these results are essential in designing new system and in specifying high-dissipation elements such as power supplies.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115586840","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88335
A. Skjelines, G. Snilsberg, E. Munchow
The authors describe the expectations a computer user should have of his UPS (uninterruptible power supply) system, and how these expectations are satisfied in the new Siemens B41 model. The computer load characteristics are discussed, and a list of essential and 'good to have' characteristics is presented. The new model is presented with main circuit diagram, description of the control electronics, and mechanical design. Voltage and current waveforms are also shown.<>
{"title":"Matching a UPS to the computer market","authors":"A. Skjelines, G. Snilsberg, E. Munchow","doi":"10.1109/INTLEC.1989.88335","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88335","url":null,"abstract":"The authors describe the expectations a computer user should have of his UPS (uninterruptible power supply) system, and how these expectations are satisfied in the new Siemens B41 model. The computer load characteristics are discussed, and a list of essential and 'good to have' characteristics is presented. The new model is presented with main circuit diagram, description of the control electronics, and mechanical design. Voltage and current waveforms are also shown.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124213792","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88280
M. Grossoni, R. Fratta, F. Dal Lago
The authors describe the planning criteria used to produce a small-size redundant power supply system. This type of system is equipped with display, microprocessor autodiagnosis, and remote supervision with sinusoidal main input and output according to telephone requirements. It is shown that in order to achieve monitoring of all information in a high-performance system without compromising reliability, a solution that comprises many high-performance modules that operate in redundant parallel must be chosen. These requirements are a starting point for the realization of the rectifier module, thus adopting switching technology in a single conversion and inserting the system in a standardized measurement container. Entrusting the diagnosis element to the microprocessor and its peripherals completes the system, thus obtaining complete control of the system as well as both local and remote monitoring of all information. It is seen that the application of this power system is directed to all telecommunication systems that require uninterrupted power supply as all those systems that require a high level of reliability and performance from the power system.<>
{"title":"High capacity modular supply system for telephone users","authors":"M. Grossoni, R. Fratta, F. Dal Lago","doi":"10.1109/INTLEC.1989.88280","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88280","url":null,"abstract":"The authors describe the planning criteria used to produce a small-size redundant power supply system. This type of system is equipped with display, microprocessor autodiagnosis, and remote supervision with sinusoidal main input and output according to telephone requirements. It is shown that in order to achieve monitoring of all information in a high-performance system without compromising reliability, a solution that comprises many high-performance modules that operate in redundant parallel must be chosen. These requirements are a starting point for the realization of the rectifier module, thus adopting switching technology in a single conversion and inserting the system in a standardized measurement container. Entrusting the diagnosis element to the microprocessor and its peripherals completes the system, thus obtaining complete control of the system as well as both local and remote monitoring of all information. It is seen that the application of this power system is directed to all telecommunication systems that require uninterrupted power supply as all those systems that require a high level of reliability and performance from the power system.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125451773","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88267
B. Larsson
The author describes principles and equipment for automatic battery supervision in telephone exchanges and the advantages involved. To simplify maintenance and supervision, a computer-based system for remote supervision of batteries has been developed. The system, BMP 610, reduces the costs of maintenance to a minimum and improves the reliability. The supervisory system can supervise all types of stationary lead storage batteries. The system is part of a major power management system, the Ericsson Energymaster, for supervision of power plants and cooling plants in telephone exchanges. The supervisory system supervises many conditions of the batteries, and issues alarms if necessary. Wiring, cell voltage deviations, level of electrolyte, leakage, high temperature, low status, and short reserve time are supervised.<>
{"title":"Battery supervision in telephone exchanges","authors":"B. Larsson","doi":"10.1109/INTLEC.1989.88267","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88267","url":null,"abstract":"The author describes principles and equipment for automatic battery supervision in telephone exchanges and the advantages involved. To simplify maintenance and supervision, a computer-based system for remote supervision of batteries has been developed. The system, BMP 610, reduces the costs of maintenance to a minimum and improves the reliability. The supervisory system can supervise all types of stationary lead storage batteries. The system is part of a major power management system, the Ericsson Energymaster, for supervision of power plants and cooling plants in telephone exchanges. The supervisory system supervises many conditions of the batteries, and issues alarms if necessary. Wiring, cell voltage deviations, level of electrolyte, leakage, high temperature, low status, and short reserve time are supervised.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114697913","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88246
E. Kulzer, B. Brakus
The authors describe the new generation of Siemens microcomputer-controlled charging rectifiers, comprising a 30 A and a 100 A model. The nominal output voltage can be switched between 48 V and 60 V. For initial charging 84 V and a current that can be varied from 10%-100% * I/sub nom/ are available. As the power section is still the most up-to-date in this field, the first-generation power section with just a few minor changes could be used for the 100 A model. Because of the lower power, the power section was redimensioned for the 30 A model. The design is modular and all control modules are suitable for use in both models.<>
{"title":"The new generation of MC controlled switched mode rectifier for telecom","authors":"E. Kulzer, B. Brakus","doi":"10.1109/INTLEC.1989.88246","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88246","url":null,"abstract":"The authors describe the new generation of Siemens microcomputer-controlled charging rectifiers, comprising a 30 A and a 100 A model. The nominal output voltage can be switched between 48 V and 60 V. For initial charging 84 V and a current that can be varied from 10%-100% * I/sub nom/ are available. As the power section is still the most up-to-date in this field, the first-generation power section with just a few minor changes could be used for the 100 A model. Because of the lower power, the power section was redimensioned for the 30 A model. The design is modular and all control modules are suitable for use in both models.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129581590","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88291
R. Nelson
Elevated-temperature data and test methods are presented for Gates products commonly used in telecommunications applications. Failure modes are enumerated and life projections based on these tests are presented and evaluated; where possible, comparisons are made with actual product field failure results and it is found that substantial discrepancies exist. Temperature factors in both laboratory testing and field conditions are discussed and simulations of temperature effects in above-ground cabinets show that life projections based on average daily temperatures may be overly optimistic. It is shown that temperature and cell chemistry can have a dramatic impact on product life at elevated temperatures. Accelerated-life tests at 60-80 degrees C show that Gates products will meet or exceed that published float life of 8-12 years at 23 degrees C. Thermal effects in telecommunication applications are such that the interior of the battery will always be hotter than the surrounding environment by some factor, the latter having a profound impact upon battery life.<>
{"title":"Accelerated-life testing and thermal effects in valve-regulated lead-acid batteries","authors":"R. Nelson","doi":"10.1109/INTLEC.1989.88291","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88291","url":null,"abstract":"Elevated-temperature data and test methods are presented for Gates products commonly used in telecommunications applications. Failure modes are enumerated and life projections based on these tests are presented and evaluated; where possible, comparisons are made with actual product field failure results and it is found that substantial discrepancies exist. Temperature factors in both laboratory testing and field conditions are discussed and simulations of temperature effects in above-ground cabinets show that life projections based on average daily temperatures may be overly optimistic. It is shown that temperature and cell chemistry can have a dramatic impact on product life at elevated temperatures. Accelerated-life tests at 60-80 degrees C show that Gates products will meet or exceed that published float life of 8-12 years at 23 degrees C. Thermal effects in telecommunication applications are such that the interior of the battery will always be hotter than the surrounding environment by some factor, the latter having a profound impact upon battery life.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129976535","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88275
V. J. Zhuikov, A. Leonov, R. Strzelecki
Nonlinear electrotechnic systems with electric power inverters can be described by equations with constant or convertible commutation moments depending on the type of semiconductor element model used. To investigate such systems a qualitatively new theory is needed that is capable of a comparatively deep analysis of the characteristics of the objects studied. Recent studies of the incidental fluctuation of different quantities were mainly based on qualitative dynamic systems theory, which could not elucidate the chaotic process structure as it does not use the incidental perturbations. It is suggested that the stochastic regimes found in determined systems, the notion of the strange attractor in dynamic systems theory, the theory of self-organization, and Feigenbaum's theory allow a more complete investigation of the chaotic behavior of a large number of nonlinear systems.<>
{"title":"Chaotic modes in electrotechnical system with transducers","authors":"V. J. Zhuikov, A. Leonov, R. Strzelecki","doi":"10.1109/INTLEC.1989.88275","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88275","url":null,"abstract":"Nonlinear electrotechnic systems with electric power inverters can be described by equations with constant or convertible commutation moments depending on the type of semiconductor element model used. To investigate such systems a qualitatively new theory is needed that is capable of a comparatively deep analysis of the characteristics of the objects studied. Recent studies of the incidental fluctuation of different quantities were mainly based on qualitative dynamic systems theory, which could not elucidate the chaotic process structure as it does not use the incidental perturbations. It is suggested that the stochastic regimes found in determined systems, the notion of the strange attractor in dynamic systems theory, the theory of self-organization, and Feigenbaum's theory allow a more complete investigation of the chaotic behavior of a large number of nonlinear systems.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130802619","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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