Frequency selective surfaces(FSSs)play an important role in wireless systems as these can be used as filters,in isolating the unwanted radiation,in microstrip patch antennas for improving the performance of these ante...Frequency selective surfaces(FSSs)play an important role in wireless systems as these can be used as filters,in isolating the unwanted radiation,in microstrip patch antennas for improving the performance of these antennas and in other 5G applications.The analysis and design of the double concentric ring frequency selective surface(DCRFSS)is presented in this research.In the sub-6 GHz 5G FR1 spectrum,a computational synthesis technique for creating DCRFSS based spatial filters is proposed.The analytical tools presented in this study can be used to gain a better understanding of filtering processes and for constructing the spatial filters.Variation of the loop sizes,angles of incidence,and polarization of the concentric rings are the factors which influence the transmission coefficient as per the thorough investigation performed in this paper.A novel synthesis approach based on mathematical equations that may be used to determine the physical parameters ofDCRFSSbased spatial filters is presented.The proposed synthesis technique is validated by comparing results from high frequency structure simulator(HFSS),Ansys electronic desktop circuit editor,and an experimental setup.Furthermore,the findings acquired from a unit cell are expanded to a 2×2 array,which shows identical performance and therefore proves its stability.展开更多
This research proposes a synergistic meta-heuristic algorithm for solving the extreme operational complications of combined heat and power economic dispatch problem towards the advantageous economic outcomes on the co...This research proposes a synergistic meta-heuristic algorithm for solving the extreme operational complications of combined heat and power economic dispatch problem towards the advantageous economic outcomes on the cost of generation. The combined heat and power (CHP) is a system that provides electricity and thermal energy concurrently. For its extraordinary efficiency and significant emission reduction, it is considered a promising energy prospect. The broad application of combined heat and power units requires the joint dispatch of power and heating systems, in which the modelling of combined heat and power units plays a vital role. The present research employs the genetic optimization algorithm to evaluate the cost function, heat and power dispatch values encountered in a system with simple cycle cogeneration unit and quadratic cost function. The system was first modeled to determine the various parameters of combined heat and power units towards solving its economic dispatch problem directly. In order for modelling to be done, a general structure of combined heat and power must be defined. The test system considered consists of four units: two conventional power units, one combined heat and power unit and one heat-only unit. The algorithm was applied to test system while taking into account the power and heat units, bounds of the units and feasible operation region of cogeneration unit. Output decision variables of 4-unit test systems plus cost function from Genetic Algorithm (GA), was determined using appropriate codes. The proposed algorithm produced a well spread and diverse optimal solution and also converged reasonably to the actual optimal solution in 51 iterations. The result obtained compared favourably with that obtained with the direct solution algorithm discussed in a previous paper. We conclude that the genetic algorithm is quite efficient in dealing with non-convex and constrained combined heat and power economic dispatch problem.展开更多
The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) com...The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) communication systems. We consider an uplink NOMA scenario for such a satellite-aerial-ground integrated network where multiple users communicate with satellite under the help of an Unmanned Aerial Vehicle(UAV) as an aerial relay equipped with a phased array. Supposing that buffer-aided decode-and-forward protocol is adopted at the UAV relay, we first formulate an optimization problem to maximize Ergodic Sum Rate(ESR) of the considered system subject to individual power constraint and quality-of-service constraint of each user.Then, with known imperfect channel state information of each user, we propose a joint power allocation and robust Beam Forming(BF) iterative algorithm to maximize ESR for the user-to-UAV link. Besides, to take the advantages of Free-Space Optical(FSO) and millimeter Wave(mmWave)communications, we present a switch-based hybrid FSO/mmWave scheme and a robust BF algorithm for the UAV-to-satellite link to achieve higher rate. Moreover, a closed-form ESR expression is derived. Finally, the effectiveness and correctness of the proposed solutions are verified by numerical simulations, and the performance evaluation results show that the proposed solutions not only achieve performance enhancement and robustness, but also outperform the orthogonal multiple access significantly.展开更多
The conventional Kalman filter is based on the assumption of non-delayed measurements. Several modifications appear to address this problem, but they are constrained by two crucial assumptions: 1) the delay is an inte...The conventional Kalman filter is based on the assumption of non-delayed measurements. Several modifications appear to address this problem, but they are constrained by two crucial assumptions: 1) the delay is an integer multiple of the sampling interval, and 2) a stochastic model representing the relationship between delayed measurements and a sequence of possible non-delayed measurements is known. Practical problems often fail to satisfy these assumptions, leading to poor estimation accuracy and frequent track-failure. This paper introduces a new variant of the Kalman filter, which is free from the stochastic model requirement and addresses the problem of fractional delay.The proposed algorithm fixes the maximum delay(problem specific), which can be tuned by the practitioners for varying delay possibilities. A sequence of hypothetically defined intermediate instants characterizes fractional delays while maximum likelihood based delay identification could preclude the stochastic model requirement. Fractional delay realization could help in improving estimation accuracy. Moreover, precluding the need of a stochastic model could enhance the practical applicability. A comparative analysis with ordinary Kalman filter shows the high estimation accuracy of the proposed method in the presence of delay.展开更多
Mission-critical IEC 61850 system architectures are designed to tolerate hardware failures to achieve the highest reliability performance.Hence,multi-channel systems are used in such systems within industrial faciliti...Mission-critical IEC 61850 system architectures are designed to tolerate hardware failures to achieve the highest reliability performance.Hence,multi-channel systems are used in such systems within industrial facilities to isolate machinery when there are process abnormalities.Inevitably,multi-channel systems introduce Common Cause Failure(CCF)since the subsystems can rarely be independent.This paper integrates CCF into the Markov reliability model to enhance the model flexibility to investigate synchronous generator intra-bay SCN architecture reliability performance considering the quality of repairs and CCF.The Markov process enables integration of the impact of CCF factors on system performance.The case study results indicate that CCF,coupled with imperfect repairs,significantly reduce system reliability performance.High sensitivity is observed at low levels of CCF,whereas the highest level of impact occurs when the system diagnostic coverage is 99%based on ISO 13849-1,and reduces as the diagnostic coverage level reduces.Therefore,it is concluded that the severity of CCF depends more on system diagnostic coverage level than the repair efficiency,although both factors impact the system overall performance.Hence,CCF should be con-sidered in determining the reliability performance of mission-critical communication networks in power distribution centres.展开更多
Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900℃ by applying a new method to continuously monitor the char surface activity.Benzene vapor was continuously forced to pass t...Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900℃ by applying a new method to continuously monitor the char surface activity.Benzene vapor was continuously forced to pass through a micro fixed bed of char with residence time as short as 7.6 ms,and then detected continuously by a flame-ionization detector.Results showed the presence of two different types of char surfaces;consumptive Type I surface and non-consumptive(sustainable)Type II surface.Type I surface of a partially CO_(2)-gasified char had an capacity of carbon deposit from benzene over 20 wt%-char and an initial activity(represented by a first-order rate constant)as high as 160 s−1.Both of them decreased with increasing carbon deposit due to consumption of micropores accessible to benzene,and finally became zero leaving Type II surface that had a very stable activity with rate constant of 4 s−1.The chars without gasification had capacities of Type I surfaces smaller by two orders of magnitude than the partially gasified char,while the Type II surfaces had activities similar to that of the partially gasified char.It was found that Type II surface converted benzene into not only carbon deposit but also diaromatics and even greater aromatics.Composition of the greater aromatics was unknown because they were deposited onto the reactor wall immediately after passing through the char bed.展开更多
We propose a reliable asymmetric dual-k spacer with SiC source/drain（S/D）pocket as a stressor for a Si channel.This enhances the device performance in terms of electron mobility（eMobility）,current driving capabili...We propose a reliable asymmetric dual-k spacer with SiC source/drain（S/D）pocket as a stressor for a Si channel.This enhances the device performance in terms of electron mobility（eMobility）,current driving capabilities,transconductance（G_m）and subthreshold slope（SS）.The improved performance is an amalgamation of longitudinal tensile stress along the channel and reduced series resistance.We analysed the variation in drive current for different values of carbon（C）mole fraction y in Si_（1-y）C_y.It is found that the mole fraction also helps to improve device lifetime,performance enhancement also pointed by transconductance variation with the gate length.All the simulations are performed in the 3-D Sentaurus TCAD tool.The proposed device structure achieved ION=2.17 mA/μm for Si_（0.3）C_（0.7） and found that Si_（0.5）C_（0.5） is more suitable for the perspective of a process variation effect for 14 nm as the gate length.We introduce reliability issues and their solutions for Si（1-y）Cy FinFET for the first time.展开更多
In this paper, analysis of DC and analog/RF performance on cylindrical gate-all-around tunnel fieldeffect transistor（TFET） has been made using distinct device geometry. Firstly, performance parameters of GAATFET are...In this paper, analysis of DC and analog/RF performance on cylindrical gate-all-around tunnel fieldeffect transistor（TFET） has been made using distinct device geometry. Firstly, performance parameters of GAATFET are analyzed in terms of drain current, gate capacitances, transconductance, source-drain conductance at different radii and channel length. Furthermore, we also produce the geometrical analysis towards the optimized investigation of radio frequency parameters like cut-off frequency, maximum oscillation frequency and gain bandwidth product using a 3D technology computer-aided design ATLAS. Due to band-to-band tunneling based current mechanism unlike MOSFET, gate-bias dependence values as primary parameters of TFET differ. We also analyze that the maximum current occurs when radii of Si is around 8 nm due to high gate controllability over channel with reduced fringing effects and also there is no change in the current of TFET on varying its length from 100 to 40 nm.However current starts to increase when channel length is further reduced for 40 to 30 nm. Both of these trades-offs affect the RF performance of the device.展开更多
文摘Frequency selective surfaces(FSSs)play an important role in wireless systems as these can be used as filters,in isolating the unwanted radiation,in microstrip patch antennas for improving the performance of these antennas and in other 5G applications.The analysis and design of the double concentric ring frequency selective surface(DCRFSS)is presented in this research.In the sub-6 GHz 5G FR1 spectrum,a computational synthesis technique for creating DCRFSS based spatial filters is proposed.The analytical tools presented in this study can be used to gain a better understanding of filtering processes and for constructing the spatial filters.Variation of the loop sizes,angles of incidence,and polarization of the concentric rings are the factors which influence the transmission coefficient as per the thorough investigation performed in this paper.A novel synthesis approach based on mathematical equations that may be used to determine the physical parameters ofDCRFSSbased spatial filters is presented.The proposed synthesis technique is validated by comparing results from high frequency structure simulator(HFSS),Ansys electronic desktop circuit editor,and an experimental setup.Furthermore,the findings acquired from a unit cell are expanded to a 2×2 array,which shows identical performance and therefore proves its stability.
文摘This research proposes a synergistic meta-heuristic algorithm for solving the extreme operational complications of combined heat and power economic dispatch problem towards the advantageous economic outcomes on the cost of generation. The combined heat and power (CHP) is a system that provides electricity and thermal energy concurrently. For its extraordinary efficiency and significant emission reduction, it is considered a promising energy prospect. The broad application of combined heat and power units requires the joint dispatch of power and heating systems, in which the modelling of combined heat and power units plays a vital role. The present research employs the genetic optimization algorithm to evaluate the cost function, heat and power dispatch values encountered in a system with simple cycle cogeneration unit and quadratic cost function. The system was first modeled to determine the various parameters of combined heat and power units towards solving its economic dispatch problem directly. In order for modelling to be done, a general structure of combined heat and power must be defined. The test system considered consists of four units: two conventional power units, one combined heat and power unit and one heat-only unit. The algorithm was applied to test system while taking into account the power and heat units, bounds of the units and feasible operation region of cogeneration unit. Output decision variables of 4-unit test systems plus cost function from Genetic Algorithm (GA), was determined using appropriate codes. The proposed algorithm produced a well spread and diverse optimal solution and also converged reasonably to the actual optimal solution in 51 iterations. The result obtained compared favourably with that obtained with the direct solution algorithm discussed in a previous paper. We conclude that the genetic algorithm is quite efficient in dealing with non-convex and constrained combined heat and power economic dispatch problem.
基金co-supported by the Key International Cooperation Research Project,China(No.61720106003)Jiangsu Province Science and Technology Project,China(No.BE2021031)+4 种基金the Shanghai Aerospace Science and Technology Innovation Foundation,China(No.SAST2019-095)NUPTSF(No.NY220111)the Research Project of Science and Technology on Complex Electronic System Simulation Laboratory,China(No.DXZT-JC-ZZ-2019-009)the National Natural Science Foundation of China(No.61801234)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.KYCX210739)。
文摘The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) communication systems. We consider an uplink NOMA scenario for such a satellite-aerial-ground integrated network where multiple users communicate with satellite under the help of an Unmanned Aerial Vehicle(UAV) as an aerial relay equipped with a phased array. Supposing that buffer-aided decode-and-forward protocol is adopted at the UAV relay, we first formulate an optimization problem to maximize Ergodic Sum Rate(ESR) of the considered system subject to individual power constraint and quality-of-service constraint of each user.Then, with known imperfect channel state information of each user, we propose a joint power allocation and robust Beam Forming(BF) iterative algorithm to maximize ESR for the user-to-UAV link. Besides, to take the advantages of Free-Space Optical(FSO) and millimeter Wave(mmWave)communications, we present a switch-based hybrid FSO/mmWave scheme and a robust BF algorithm for the UAV-to-satellite link to achieve higher rate. Moreover, a closed-form ESR expression is derived. Finally, the effectiveness and correctness of the proposed solutions are verified by numerical simulations, and the performance evaluation results show that the proposed solutions not only achieve performance enhancement and robustness, but also outperform the orthogonal multiple access significantly.
基金supported by the Department of Science and Technology,Government of India under the Inspire Faculty Award
文摘The conventional Kalman filter is based on the assumption of non-delayed measurements. Several modifications appear to address this problem, but they are constrained by two crucial assumptions: 1) the delay is an integer multiple of the sampling interval, and 2) a stochastic model representing the relationship between delayed measurements and a sequence of possible non-delayed measurements is known. Practical problems often fail to satisfy these assumptions, leading to poor estimation accuracy and frequent track-failure. This paper introduces a new variant of the Kalman filter, which is free from the stochastic model requirement and addresses the problem of fractional delay.The proposed algorithm fixes the maximum delay(problem specific), which can be tuned by the practitioners for varying delay possibilities. A sequence of hypothetically defined intermediate instants characterizes fractional delays while maximum likelihood based delay identification could preclude the stochastic model requirement. Fractional delay realization could help in improving estimation accuracy. Moreover, precluding the need of a stochastic model could enhance the practical applicability. A comparative analysis with ordinary Kalman filter shows the high estimation accuracy of the proposed method in the presence of delay.
文摘Mission-critical IEC 61850 system architectures are designed to tolerate hardware failures to achieve the highest reliability performance.Hence,multi-channel systems are used in such systems within industrial facilities to isolate machinery when there are process abnormalities.Inevitably,multi-channel systems introduce Common Cause Failure(CCF)since the subsystems can rarely be independent.This paper integrates CCF into the Markov reliability model to enhance the model flexibility to investigate synchronous generator intra-bay SCN architecture reliability performance considering the quality of repairs and CCF.The Markov process enables integration of the impact of CCF factors on system performance.The case study results indicate that CCF,coupled with imperfect repairs,significantly reduce system reliability performance.High sensitivity is observed at low levels of CCF,whereas the highest level of impact occurs when the system diagnostic coverage is 99%based on ISO 13849-1,and reduces as the diagnostic coverage level reduces.Therefore,it is concluded that the severity of CCF depends more on system diagnostic coverage level than the repair efficiency,although both factors impact the system overall performance.Hence,CCF should be con-sidered in determining the reliability performance of mission-critical communication networks in power distribution centres.
基金A part of this work was financially supported by New Energy and Industrial Technology Development Organization,Japan,for an R/D project on next-generation coal gasification system.Another part was supported by the Japan Society for the Promotion of Science(JSPS)for Grant-in-Aid for Scientific Research(Grant 17H01340).
文摘Kinetics of thermal decomposition of benzene on lignite-derived char was investigated at 900℃ by applying a new method to continuously monitor the char surface activity.Benzene vapor was continuously forced to pass through a micro fixed bed of char with residence time as short as 7.6 ms,and then detected continuously by a flame-ionization detector.Results showed the presence of two different types of char surfaces;consumptive Type I surface and non-consumptive(sustainable)Type II surface.Type I surface of a partially CO_(2)-gasified char had an capacity of carbon deposit from benzene over 20 wt%-char and an initial activity(represented by a first-order rate constant)as high as 160 s−1.Both of them decreased with increasing carbon deposit due to consumption of micropores accessible to benzene,and finally became zero leaving Type II surface that had a very stable activity with rate constant of 4 s−1.The chars without gasification had capacities of Type I surfaces smaller by two orders of magnitude than the partially gasified char,while the Type II surfaces had activities similar to that of the partially gasified char.It was found that Type II surface converted benzene into not only carbon deposit but also diaromatics and even greater aromatics.Composition of the greater aromatics was unknown because they were deposited onto the reactor wall immediately after passing through the char bed.
基金the M.P.Council of Science & Technology,Bhopal,India,for financial support under the R&D project scheme No:1950/CST/R&D/Phy & Engg Sc/2015:27~(th) Aug 2015
文摘We propose a reliable asymmetric dual-k spacer with SiC source/drain（S/D）pocket as a stressor for a Si channel.This enhances the device performance in terms of electron mobility（eMobility）,current driving capabilities,transconductance（G_m）and subthreshold slope（SS）.The improved performance is an amalgamation of longitudinal tensile stress along the channel and reduced series resistance.We analysed the variation in drive current for different values of carbon（C）mole fraction y in Si_（1-y）C_y.It is found that the mole fraction also helps to improve device lifetime,performance enhancement also pointed by transconductance variation with the gate length.All the simulations are performed in the 3-D Sentaurus TCAD tool.The proposed device structure achieved ION=2.17 mA/μm for Si_（0.3）C_（0.7） and found that Si_（0.5）C_（0.5） is more suitable for the perspective of a process variation effect for 14 nm as the gate length.We introduce reliability issues and their solutions for Si（1-y）Cy FinFET for the first time.
基金supported by the Council of Scientific and Industrial Research(CSIR)Funded Research Project,Grant No.22/0651/14/EMR-II,Government of India
文摘In this paper, analysis of DC and analog/RF performance on cylindrical gate-all-around tunnel fieldeffect transistor（TFET） has been made using distinct device geometry. Firstly, performance parameters of GAATFET are analyzed in terms of drain current, gate capacitances, transconductance, source-drain conductance at different radii and channel length. Furthermore, we also produce the geometrical analysis towards the optimized investigation of radio frequency parameters like cut-off frequency, maximum oscillation frequency and gain bandwidth product using a 3D technology computer-aided design ATLAS. Due to band-to-band tunneling based current mechanism unlike MOSFET, gate-bias dependence values as primary parameters of TFET differ. We also analyze that the maximum current occurs when radii of Si is around 8 nm due to high gate controllability over channel with reduced fringing effects and also there is no change in the current of TFET on varying its length from 100 to 40 nm.However current starts to increase when channel length is further reduced for 40 to 30 nm. Both of these trades-offs affect the RF performance of the device.
