To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by depl...To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by deploying a large number of Access Points(APs)in the service area.However,since the energy consumption of APs generally accounts for a substantial part of the communication system,how to deal with the consequent energy issue is a challenging task for a mobile network with densely deployed APs.In this paper,we propose an intelligent AP switching on/off scheme to reduce the system energy consumption with the prerequisite of guaranteeing the quality of service,where the signaling overhead is also taken into consideration to ensure the stability of the network.First,based on historical traffic data,a long short-term memory method is introduced to predict the future traffic distribution,by which we can roughly determine when the AP switching operation should be triggered;second,we present an efficient three-step AP selection strategy to determine which of the APs would be switched on or off;third,an AP switching scheme with a threshold is proposed to adjust the switching frequency so as to improve the stability of the system.Experiment results indicate that our proposed traffic forecasting method performs well in practical scenarios,where the normalized root mean square error is within 10%.Furthermore,the achieved energy-saving is more than 28% on average with a reasonable outage probability and switching frequency for an area served by 40 APs in a commercial mobile network.展开更多
This paper studies the regional stability for positive switched linear systems with multi-equilibrium points （PSLS-MEP）. First, a sufficient condition is presented for the regional stability of PSLS-MEP via a common...This paper studies the regional stability for positive switched linear systems with multi-equilibrium points （PSLS-MEP）. First, a sufficient condition is presented for the regional stability of PSLS-MEP via a common linear Lyapunov function. Second, by establishing multiple Lyapunov functions, a dwell time based condition is proposed for the regional stability analysis. Third, a suprasphere which contains all equilibrium points is constructed as a stability region of the considered PSLS-MEP, which is less conservative than existing results. Finally, the study of an illustrative example shows that the obtained results are effective in the regional stability analysis of PSLS-MEP.展开更多
The present paper studies the coalescence of pore columns in ferroelectric ceramics driven by back and forth domain switching under cyclic electric field. A finite element method that incorporates mass transfer capaci...The present paper studies the coalescence of pore columns in ferroelectric ceramics driven by back and forth domain switching under cyclic electric field. A finite element method that incorporates mass transfer capacity is formulated to simulate the evolution of point defects subjected to the kinetics of pore surface diffusion and domain wall migration. The merge of point defects provides a mechanism for the vacancy agglomeration that leads to the formation of large pores or microcracks.展开更多
随着新型电力系统的建设,用户对于供电可靠性的需求日益升高,而各类开关作为配电网自愈过程的主要执行设备,其优化配置对于提高系统可靠性起到关键作用。新型柔性软开关(soft open point,SOP)具有远程控制与电压支撑的特点,可替代传统...随着新型电力系统的建设,用户对于供电可靠性的需求日益升高,而各类开关作为配电网自愈过程的主要执行设备,其优化配置对于提高系统可靠性起到关键作用。新型柔性软开关(soft open point,SOP)具有远程控制与电压支撑的特点,可替代传统配电网中的联络开关,实现各馈线之间的柔性互联,为改善配电网可靠性提供了新的思路。为此,该文提出一种显式集成可靠性表达式的柔性配电网多类型开关优化配置模型,对配电网自愈过程不同阶段中柔性开关与其他智能开关的动作耦合关系进行精细化建模,建立不同开关类型与系统可靠性指标之间的显式解析关系,从而得到最优的多类型开关配置方案。最后,在配电网算例中对该模型进行测试,验证模型的正确性和有效性。展开更多
本文主要探讨了大功率三电平应用中3.3 kV SiC MOSFET和IGBT的混合应用问题,针对外管高频、内管低频的调制策略中不同箝位管脉冲时序对三电平有源中点箝位(ANPC)拓扑换流路径、开关损耗以及开关特性等关键因素的影响开展分析,实验验证...本文主要探讨了大功率三电平应用中3.3 kV SiC MOSFET和IGBT的混合应用问题,针对外管高频、内管低频的调制策略中不同箝位管脉冲时序对三电平有源中点箝位(ANPC)拓扑换流路径、开关损耗以及开关特性等关键因素的影响开展分析,实验验证了不同箝位管脉冲时序对SiC MOSFET和IGBT的动态特性和开关损耗的影响。展开更多
基金partially supported by the National Natural Science Foundation of China under Grants 61801208,61931023,and U1936202.
文摘To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by deploying a large number of Access Points(APs)in the service area.However,since the energy consumption of APs generally accounts for a substantial part of the communication system,how to deal with the consequent energy issue is a challenging task for a mobile network with densely deployed APs.In this paper,we propose an intelligent AP switching on/off scheme to reduce the system energy consumption with the prerequisite of guaranteeing the quality of service,where the signaling overhead is also taken into consideration to ensure the stability of the network.First,based on historical traffic data,a long short-term memory method is introduced to predict the future traffic distribution,by which we can roughly determine when the AP switching operation should be triggered;second,we present an efficient three-step AP selection strategy to determine which of the APs would be switched on or off;third,an AP switching scheme with a threshold is proposed to adjust the switching frequency so as to improve the stability of the system.Experiment results indicate that our proposed traffic forecasting method performs well in practical scenarios,where the normalized root mean square error is within 10%.Furthermore,the achieved energy-saving is more than 28% on average with a reasonable outage probability and switching frequency for an area served by 40 APs in a commercial mobile network.
基金supported by National Natural Science Foundation of China(No.61374065)the Research Fund for the Taishan Scholar Project of Shandong Province
文摘This paper studies the regional stability for positive switched linear systems with multi-equilibrium points （PSLS-MEP）. First, a sufficient condition is presented for the regional stability of PSLS-MEP via a common linear Lyapunov function. Second, by establishing multiple Lyapunov functions, a dwell time based condition is proposed for the regional stability analysis. Third, a suprasphere which contains all equilibrium points is constructed as a stability region of the considered PSLS-MEP, which is less conservative than existing results. Finally, the study of an illustrative example shows that the obtained results are effective in the regional stability analysis of PSLS-MEP.
基金The project supported by the National Natural Science Foundation of China (10332020 and 10121202)the National 973 Project (2004CB619304)
文摘The present paper studies the coalescence of pore columns in ferroelectric ceramics driven by back and forth domain switching under cyclic electric field. A finite element method that incorporates mass transfer capacity is formulated to simulate the evolution of point defects subjected to the kinetics of pore surface diffusion and domain wall migration. The merge of point defects provides a mechanism for the vacancy agglomeration that leads to the formation of large pores or microcracks.
文摘随着新型电力系统的建设,用户对于供电可靠性的需求日益升高,而各类开关作为配电网自愈过程的主要执行设备,其优化配置对于提高系统可靠性起到关键作用。新型柔性软开关(soft open point,SOP)具有远程控制与电压支撑的特点,可替代传统配电网中的联络开关,实现各馈线之间的柔性互联,为改善配电网可靠性提供了新的思路。为此,该文提出一种显式集成可靠性表达式的柔性配电网多类型开关优化配置模型,对配电网自愈过程不同阶段中柔性开关与其他智能开关的动作耦合关系进行精细化建模,建立不同开关类型与系统可靠性指标之间的显式解析关系,从而得到最优的多类型开关配置方案。最后,在配电网算例中对该模型进行测试,验证模型的正确性和有效性。
文摘本文主要探讨了大功率三电平应用中3.3 kV SiC MOSFET和IGBT的混合应用问题,针对外管高频、内管低频的调制策略中不同箝位管脉冲时序对三电平有源中点箝位(ANPC)拓扑换流路径、开关损耗以及开关特性等关键因素的影响开展分析,实验验证了不同箝位管脉冲时序对SiC MOSFET和IGBT的动态特性和开关损耗的影响。
