A delay-locked loop based hybrid phase conjugator (DLL-HPC) is presented as a possible solution for 5G beamforming. Theoretical background, unique capabilities, and experimental verification are presented. The proposed DLL-HPC provides backwards compatibility with existing beamforming protocols as well as sub-millisecond beamsteering and automatic mobile target tracking with zero communication overhead. A proof-of-concept DLL-HPC prototype has been constructed from commercially available components to operate in the 5G NR-FR1 band, indicating that the technique can be readily adopted with available technology.
{"title":"A High-Speed DLL-Based Hybrid Phase Conjugator for 5G Beamforming","authors":"Michael Bolt, M. Adams","doi":"10.4236/cs.2020.113003","DOIUrl":"https://doi.org/10.4236/cs.2020.113003","url":null,"abstract":"A delay-locked loop based hybrid phase conjugator (DLL-HPC) is presented as a possible solution for 5G beamforming. Theoretical background, unique capabilities, and experimental verification are presented. The proposed DLL-HPC provides backwards compatibility with existing beamforming protocols as well as sub-millisecond beamsteering and automatic mobile target tracking with zero communication overhead. A proof-of-concept DLL-HPC prototype has been constructed from commercially available components to operate in the 5G NR-FR1 band, indicating that the technique can be readily adopted with available technology.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47703482","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}
This paper presents a higher order voltage and current mode low pass or high pass filter for wave active filter based on Voltage Differencing Transconductance Amplifiers (VDTAs). The wave equivalent variable technique and topological simulation as well as operational realization using wave variables techniques are proposed for basic active building blocks of wave active filters. The proposed wave equivalent technique is employed for wave active filter with the proper selection of the terminal connections. This work presented the basic element for the realizing wave active filter is the series inductor with parallel grounded capacitor. The proposed wave active filter is verified by realizing a 4th order low pass and high pass Butterworth filter with minimum power consumption at ±0.82 V using SPICE simulation with 0.18 μm TSMC CMOS technology parameters.
{"title":"CMOS Realization of VDTA Based Electronically Tunable Wave Active Filter with Minimum Power Consumption at Low Supply Voltage ±0.82 V","authors":"G. Singh","doi":"10.4236/cs.2020.112002","DOIUrl":"https://doi.org/10.4236/cs.2020.112002","url":null,"abstract":"This paper presents a higher order voltage and current mode low pass or high pass filter for wave active filter based on Voltage Differencing Transconductance Amplifiers (VDTAs). The wave equivalent variable technique and topological simulation as well as operational realization using wave variables techniques are proposed for basic active building blocks of wave active filters. The proposed wave equivalent technique is employed for wave active filter with the proper selection of the terminal connections. This work presented the basic element for the realizing wave active filter is the series inductor with parallel grounded capacitor. The proposed wave active filter is verified by realizing a 4th order low pass and high pass Butterworth filter with minimum power consumption at ±0.82 V using SPICE simulation with 0.18 μm TSMC CMOS technology parameters.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44043736","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}
Multimedia based virtual learning system (MMVLS) is a web-based platform for teaching and learning with a virtual teacher within a virtual classroom. This research was motivated by the problems confronting the traditional institutions of higher learning in Nigeria which include inadequate funding, lack of infrastructures, inadequate teaching and learning facilities, limited slots for admission known as carrying capacity, a limited number of lecturers/instructors in the tertiary institutions in Nigeria. The objective of this research is to develop a multimedia based virtual learning system for Nigerian tertiary institutions to be used in academic processes for teaching and learning. The methodology used is Object Oriented Design Methodology (OODM) with the following web development tools PHP, JavaScript, Bootstrap 3, HTML5, CSS4, Apache, and MYSQL as database. The expected result is a multimedia based virtual learning system for tertiary institutions in Nigeria which is cost effective, innovative, vibrant, individualized, learner-centric, available anytime, any place even with mobile devices. It was concluded that multimedia based virtual learning system is a veritable tool for Nigerian tertiary institutions, which when fully implemented by Nigerian tertiary institutions would help to increase the number of candidates that are given admission into our tertiary institutions and drastically reduce school dropouts as a result of candidates not gaining admission due to insufficient tertiary institutions/carrying capacity.
{"title":"A Multimedia Based Virtual Learning System: A Panacea for Nigerian Tertiary Institutions","authors":"E. Ekwonwune, Chidiebere Chukwuma Oparah","doi":"10.4236/cs.2020.111001","DOIUrl":"https://doi.org/10.4236/cs.2020.111001","url":null,"abstract":"Multimedia based virtual learning system (MMVLS) is a web-based platform for teaching and learning with a virtual teacher within a virtual classroom. This research was motivated by the problems confronting the traditional institutions of higher learning in Nigeria which include inadequate funding, lack of infrastructures, inadequate teaching and learning facilities, limited slots for admission known as carrying capacity, a limited number of lecturers/instructors in the tertiary institutions in Nigeria. The objective of this research is to develop a multimedia based virtual learning system for Nigerian tertiary institutions to be used in academic processes for teaching and learning. The methodology used is Object Oriented Design Methodology (OODM) with the following web development tools PHP, JavaScript, Bootstrap 3, HTML5, CSS4, Apache, and MYSQL as database. The expected result is a multimedia based virtual learning system for tertiary institutions in Nigeria which is cost effective, innovative, vibrant, individualized, learner-centric, available anytime, any place even with mobile devices. It was concluded that multimedia based virtual learning system is a veritable tool for Nigerian tertiary institutions, which when fully implemented by Nigerian tertiary institutions would help to increase the number of candidates that are given admission into our tertiary institutions and drastically reduce school dropouts as a result of candidates not gaining admission due to insufficient tertiary institutions/carrying capacity.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45421692","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}
Mussa Elsaadi, Hend Muhmed, Mohammed Abd Alraheem, Hajir Miftah, Omar Salah
This paper presents a model of cancer diagnosis using principal electrical parameters of tumor cells such as the relative permittivity and the conductivity. The proposed model involves a square microstrip antenna and breast phantom comprising a tumor cell. The radiation properties of the designed antenna at the ISM bands, such as the Return Loss (RL), the current density, the electrical field and the Specific Absorption Rate (SAR) are exploited for diagnosing purposes. The Ansoft HFSS (13.0) simulated results show that the difference in terms of the RL, the current density, the electrical field and the SAR is higher than 2 dB, 40 A/m2, 100 V/m and 20 W/kg respectively, once the tumor exists inside the breast model. This proposed technique in turn can be exploited to distinguish malignant cells inside the women breast in earlier stages as compared to other traditional techniques such as mammography, X-ray, ultra-sound, tomography and MRI.
{"title":"Square Patch Antenna for Breast Cancer Diagnosis at 2.45 GHz","authors":"Mussa Elsaadi, Hend Muhmed, Mohammed Abd Alraheem, Hajir Miftah, Omar Salah","doi":"10.4236/cs.2019.104004","DOIUrl":"https://doi.org/10.4236/cs.2019.104004","url":null,"abstract":"This paper presents a model of cancer diagnosis using principal electrical parameters of tumor cells such as the relative permittivity and the conductivity. The proposed model involves a square microstrip antenna and breast phantom comprising a tumor cell. The radiation properties of the designed antenna at the ISM bands, such as the Return Loss (RL), the current density, the electrical field and the Specific Absorption Rate (SAR) are exploited for diagnosing purposes. The Ansoft HFSS (13.0) simulated results show that the difference in terms of the RL, the current density, the electrical field and the SAR is higher than 2 dB, 40 A/m2, 100 V/m and 20 W/kg respectively, once the tumor exists inside the breast model. This proposed technique in turn can be exploited to distinguish malignant cells inside the women breast in earlier stages as compared to other traditional techniques such as mammography, X-ray, ultra-sound, tomography and MRI.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43395707","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}
Mussa Elsaadi, Yousef Aid, Mustafa Abbas, Amani Embarek, Khaleel Salih
The primary intent of this paper is to investigate the potential of using a slotted circular patch antenna at 2.45 GHz for breast tumor hyperthermia treatment. A cancer treatment model consisting of a microstrip patch antenna and breast phantom comprising tumor is designed and simulated in CST Studio Suite 2018. The radiation properties of the proposed antenna attain 3 dB beam width of 74.1° and 70.5° for the E-Plane and the H-plane, respectively. The breast phantom is exposed to the designed antenna radiation for 10 minutes, leading to raise the breast phantom temperature by 8.5°C and 11.4°C once the antenna pumped power is 1.5 and 2 watt, respectively. By considering 10 minutes as an exposure time, the breast temperature as a function of the applied antenna power is studied and compared with previous published results.
本文的主要目的是研究在2.45GHz下使用开槽圆形贴片天线用于乳腺肿瘤热疗的潜力。在CST Studio Suite 2018中设计并模拟了由微带贴片天线和包含肿瘤的乳房模型组成的癌症治疗模型。所提出的天线的辐射特性在E平面和H平面分别达到74.1°和70.5°的3dB波束宽度。乳房模型暴露在设计的天线辐射下10分钟，一旦天线泵浦功率分别为1.5和2瓦，乳房模型的温度将分别升高8.5°C和11.4°C。通过将10分钟视为暴露时间，研究了乳房温度作为所施加天线功率的函数，并将其与先前发表的结果进行了比较。
{"title":"Hyperthermia for Breast Cancer Treatment Using Slotted Circular Patch Antenna","authors":"Mussa Elsaadi, Yousef Aid, Mustafa Abbas, Amani Embarek, Khaleel Salih","doi":"10.4236/cs.2019.103003","DOIUrl":"https://doi.org/10.4236/cs.2019.103003","url":null,"abstract":"The primary intent of this paper is to investigate the potential of using a slotted circular patch antenna at 2.45 GHz for breast tumor hyperthermia treatment. A cancer treatment model consisting of a microstrip patch antenna and breast phantom comprising tumor is designed and simulated in CST Studio Suite 2018. The radiation properties of the proposed antenna attain 3 dB beam width of 74.1° and 70.5° for the E-Plane and the H-plane, respectively. The breast phantom is exposed to the designed antenna radiation for 10 minutes, leading to raise the breast phantom temperature by 8.5°C and 11.4°C once the antenna pumped power is 1.5 and 2 watt, respectively. By considering 10 minutes as an exposure time, the breast temperature as a function of the applied antenna power is studied and compared with previous published results.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45852743","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}
Based on 2-D device simulations and mixed-mode transient simulations, DC and transient discharge characteristics of a usual diode string utilizing a standard CMOS process, and a diode string utilizing a triple-well CMOS process, which can serve as an essential VDD-VSS clamp device for CMOS input ESD protection were compared. Transient discharge characteristics including peak voltages developed across gates oxides of transistors in input buffers, lattice heating inside ESD protection devices, and ratios of discharge current components at its peak inside the diode-string clamp were compared. DC standby current levels added per each input pad structure, which are the critical parameters determining usefulness of the devices, were also compared. We showed that the diode-string devices in comparison can serve successfully as a VDD-VSS clamp device for ESD protection by virtue of the dominant pnpn thyristor-related conduction mechanisms. Optimization of design parameters including anode-cathode contact spacing in each diode in the string, device width of the diode string, and number of diodes in the diode string was performed to present transient discharge and DC characteristics of some recommendable design examples, which can serve as a guideline in designing diode-string clamp devices.
{"title":"A Comparison Study of Diode-String ESD Clamps for CMOS Input Protection","authors":"J. Choi","doi":"10.4236/cs.2019.102002","DOIUrl":"https://doi.org/10.4236/cs.2019.102002","url":null,"abstract":"Based on 2-D device simulations and mixed-mode transient simulations, DC and transient discharge characteristics of a usual diode string utilizing a standard CMOS process, and a diode string utilizing a triple-well CMOS process, which can serve as an essential VDD-VSS clamp device for CMOS input ESD protection were compared. Transient discharge characteristics including peak voltages developed across gates oxides of transistors in input buffers, lattice heating inside ESD protection devices, and ratios of discharge current components at its peak inside the diode-string clamp were compared. DC standby current levels added per each input pad structure, which are the critical parameters determining usefulness of the devices, were also compared. We showed that the diode-string devices in comparison can serve successfully as a VDD-VSS clamp device for ESD protection by virtue of the dominant pnpn thyristor-related conduction mechanisms. Optimization of design parameters including anode-cathode contact spacing in each diode in the string, device width of the diode string, and number of diodes in the diode string was performed to present transient discharge and DC characteristics of some recommendable design examples, which can serve as a guideline in designing diode-string clamp devices.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47751751","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}
Dhiman Chowdhury, M. Miah, Md. Feroz Hossain, Md. Mostafijur Rahman, M. J. Hossain, Md. Nazim Uddin Sheikh, M. Hasan, Uzzal Sarker, A. Hasan
This paper documents design and modeling of a grid-connected emergency back-up power supply for medium power applications. Back-up power supplies are very important in regard to support electrical loads in the events of grid power outage. However, grid-integration of a back-up power supply substantiates continual power transfer to the loads, especially to the critical loads, which should not suffer from power interruptions. Therefore, design and circuit modeling of switching converters based reliable grid-tied emergency back-up power supply are presented in this paper. There are a rectifier-link boost derived battery charging circuit and a 4-switch push-pull power inverter circuit which are controlled by high frequency pulse width modulation (PWM) signals. This paper presents a state averaging model and Laplace domain transfer function of the charging circuit and a switching converter model of the power inverter circuit. A changeover relay based transfer switch controls the power flow towards the utility loads. During off-grid situations, loads are fed power by the proposed inverter circuit and during on-grid situations, battery is charged by an ac-link rectifier-fed boost converter. However, there is a relay switching circuit to control the charging phenomenon of the battery. The proposed design is simulated in PLECS and the simulation results corroborate the reliability of the presented framework.
{"title":"Grid-Connected Emergency Back-Up Power Supply","authors":"Dhiman Chowdhury, M. Miah, Md. Feroz Hossain, Md. Mostafijur Rahman, M. J. Hossain, Md. Nazim Uddin Sheikh, M. Hasan, Uzzal Sarker, A. Hasan","doi":"10.4236/CS.2019.101001","DOIUrl":"https://doi.org/10.4236/CS.2019.101001","url":null,"abstract":"This paper documents design and modeling of a grid-connected emergency back-up power supply for medium power applications. Back-up power supplies are very important in regard to support electrical loads in the events of grid power outage. However, grid-integration of a back-up power supply substantiates continual power transfer to the loads, especially to the critical loads, which should not suffer from power interruptions. Therefore, design and circuit modeling of switching converters based reliable grid-tied emergency back-up power supply are presented in this paper. There are a rectifier-link boost derived battery charging circuit and a 4-switch push-pull power inverter circuit which are controlled by high frequency pulse width modulation (PWM) signals. This paper presents a state averaging model and Laplace domain transfer function of the charging circuit and a switching converter model of the power inverter circuit. A changeover relay based transfer switch controls the power flow towards the utility loads. During off-grid situations, loads are fed power by the proposed inverter circuit and during on-grid situations, battery is charged by an ac-link rectifier-fed boost converter. However, there is a relay switching circuit to control the charging phenomenon of the battery. The proposed design is simulated in PLECS and the simulation results corroborate the reliability of the presented framework.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43696317","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}
Long Zhang, Hong-Chong Wu, Ching-Hwa Cheng, Don-Gey Liu, M. Shiau, Weidian Lai, Ziwei Zheng
In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power supply module in a UPS, it would be better to reduce the output current ratio for a hotter supply module in the UPS. In this design, we implemented our regulation circuits by the UMC 0.25-μm CMOS technology with an input range from 3 V to 4.2 V and the regulated output at 1.1 V. The rated output current was 100 mA for each phase. We also employed a current-mode error-correction circuit to improve the current sharing performance based on the averaged current of each phase at the same temperature. According to our simulation results, the current sharing error can be restricted within ± 5% for the supply modules at the same temperature in our system.
{"title":"A Temperature-Based Hysteresis Buck Converter for Dynamic Current Sharing","authors":"Long Zhang, Hong-Chong Wu, Ching-Hwa Cheng, Don-Gey Liu, M. Shiau, Weidian Lai, Ziwei Zheng","doi":"10.4236/cs.2018.912019","DOIUrl":"https://doi.org/10.4236/cs.2018.912019","url":null,"abstract":"In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power supply module in a UPS, it would be better to reduce the output current ratio for a hotter supply module in the UPS. In this design, we implemented our regulation circuits by the UMC 0.25-μm CMOS technology with an input range from 3 V to 4.2 V and the regulated output at 1.1 V. The rated output current was 100 mA for each phase. We also employed a current-mode error-correction circuit to improve the current sharing performance based on the averaged current of each phase at the same temperature. According to our simulation results, the current sharing error can be restricted within ± 5% for the supply modules at the same temperature in our system.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":"09 1","pages":"213-223"},"PeriodicalIF":0.0,"publicationDate":"2018-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49155110","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}
Reducing greenhouse gases, saving energy resources and mass optimization require technological changes towards increasingly electric vehicles. At the same time, performance improvement of semiconductor and dielectric materials further promotes electronic components confinement, resulting in a significant increase of embedded power densities. In the particular case of future hybrid propulsion aircrafts, electrical power that intended to supply reactors would be converted through power electronics components mounted on power busbars and insulated by solid dielectrics materials. These dielectrics materials have to respond to various electrical constraints of use (HVDC), in spite of environment change of aircraft parameters such as low pressure, temperature and thermal cycles, humidity... Unfortunately, partial discharges phenomenon is the most problem within electrical insulation system (EIS). Based on a topological model of power busbars designed for power converters dedicated to hybrid aircraft, partial discharge studies were conducted by simulation in various charging conditions of a PTFE insulator. Simulation results, which focus on electric field thresholds criteria of partial discharge inception voltage in air, reveal a net sensitivity of a space charge accumulation and distribution on dielectrics behaviour even for low space charge density, depending on their location in dielectrics. Compared to the behaviour observed with implanted homocharges, when by increasing homocharges density from 0.5 C/m3 to 2 C/m3 we observe a decrease of electric field by 450%, simulation results show a highest risk of partial discharge inception when heterocharges are accumulated inside dielectrics. Their accumulation increases the electric field in triple points beyond electric field thresholds of partial discharge inception in air. The simulated electric field reaching 22 kV/mm with only 2 C/m3 of heterocharges density accumulated in dielectric/busbars interfaces.
{"title":"Simulation of Space Charge Impact on Partial Discharge Inception Voltage in Power Busbars Dedicated to Future Hybrid Aircrafts","authors":"M. Banda, D. Malec, J. Cambronne","doi":"10.4236/CS.2018.911018","DOIUrl":"https://doi.org/10.4236/CS.2018.911018","url":null,"abstract":"Reducing greenhouse gases, saving energy resources and mass optimization require technological changes towards increasingly electric vehicles. At the same time, performance improvement of semiconductor and dielectric materials further promotes electronic components confinement, resulting in a significant increase of embedded power densities. In the particular case of future hybrid propulsion aircrafts, electrical power that intended to supply reactors would be converted through power electronics components mounted on power busbars and insulated by solid dielectrics materials. These dielectrics materials have to respond to various electrical constraints of use (HVDC), in spite of environment change of aircraft parameters such as low pressure, temperature and thermal cycles, humidity... Unfortunately, partial discharges phenomenon is the most problem within electrical insulation system (EIS). Based on a topological model of power busbars designed for power converters dedicated to hybrid aircraft, partial discharge studies were conducted by simulation in various charging conditions of a PTFE insulator. Simulation results, which focus on electric field thresholds criteria of partial discharge inception voltage in air, reveal a net sensitivity of a space charge accumulation and distribution on dielectrics behaviour even for low space charge density, depending on their location in dielectrics. Compared to the behaviour observed with implanted homocharges, when by increasing homocharges density from 0.5 C/m3 to 2 C/m3 we observe a decrease of electric field by 450%, simulation results show a highest risk of partial discharge inception when heterocharges are accumulated inside dielectrics. Their accumulation increases the electric field in triple points beyond electric field thresholds of partial discharge inception in air. The simulated electric field reaching 22 kV/mm with only 2 C/m3 of heterocharges density accumulated in dielectric/busbars interfaces.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":"09 1","pages":"196-212"},"PeriodicalIF":0.0,"publicationDate":"2018-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41481353","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}
In a given linear, multistage, cascaded amplifier [1] comprising passive coupling circuits and active two-ports alternatively, the problem is where in the amplifier the stabilizing circuit elements should be placed to eliminate instability, and of what type and value. Our investigations are based on a new recursive formula for the determinant of tridiagonal matrices. Relation of our results to the Stern stability factor has been obtained. A verification in numerical examples has also been provided.
{"title":"Stabilization of Linear Multistage Amplifiers","authors":"Janos Ladvanszky","doi":"10.4236/CS.2018.911017","DOIUrl":"https://doi.org/10.4236/CS.2018.911017","url":null,"abstract":"In a given linear, multistage, cascaded amplifier [1] comprising passive coupling circuits and active two-ports alternatively, the problem is where in the amplifier the stabilizing circuit elements should be placed to eliminate instability, and of what type and value. Our investigations are based on a new recursive formula for the determinant of tridiagonal matrices. Relation of our results to the Stern stability factor has been obtained. A verification in numerical examples has also been provided.","PeriodicalId":63422,"journal":{"name":"电路与系统(英文)","volume":"09 1","pages":"169-195"},"PeriodicalIF":0.0,"publicationDate":"2018-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42477850","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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