Vibration measurements can be used to evaluate the operation status of power equipment and are widely applied in equipment quality inspection and fault identification.Event-sensing technology can sense the change in s...Vibration measurements can be used to evaluate the operation status of power equipment and are widely applied in equipment quality inspection and fault identification.Event-sensing technology can sense the change in surface light intensity caused by object vibration and provide a visual description of vibration behavior.Based on the analysis of the principle underlying the transformation of vibration behavior into event flow data by an event sensor,this paper proposes an algorithm to reconstruct event flow data into a relationship correlating vibration displacement and time to extract the amplitude-frequency characteristics of the vibration signal.A vibration measurement test platform is constructed,and feasibility and effectiveness tests are performed for the vibration motor and other power equipment.The results show that event-sensing technology can effectively perceive the surface vibration behavior of power and provide a wide dynamic range.Furthermore,the vibration measurement and visualization algorithm for power equipment constructed using this technology offers high measurement accuracy and efficiency.The results of this study provide a new noncontact and visual method for locating vibrations and performing amplitude-frequency analysis on power equipment.展开更多
无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进...无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进行信息解码的同时收集能量,与无小区大规模MIMO-NOMA优势互补。文中基于SWIPT研究无小区大规模MIMO-NOMA系统中的能量效率问题,通过联合优化功率分配系数和SWIPT的时隙切换(Time Switching,TS)系数,提高系统的能量效率。为了最大化能量效率,采用布谷鸟算法设计功率分配系数。考虑一种特殊情况,将所有终端的TS系数设置相同,进而推导了最佳TS系数的封闭表达式。仿真结果表明,相较于几种已有方案,文中提出的优化方案可以显著提升系统的能量效率。展开更多
In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mat...In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater,the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching,the non-powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process,and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.展开更多
980 nm InGaAs/GaAs separate confinement heterostructure (SCH) strained quantum well (QW) laser with non-absorbing facets was fabricated by using thermal treatment. Microchannel coolers with a five-layer thin oxyge...980 nm InGaAs/GaAs separate confinement heterostructure (SCH) strained quantum well (QW) laser with non-absorbing facets was fabricated by using thermal treatment. Microchannel coolers with a five-layer thin oxygen-free copper plate structure were designed and fabricated through thermal bonding in hydrogen ambient. The highest CW (continuous wave) output power of 200 W for 5-bar arrays packaged by microchannel coolers was presented.展开更多
本文研究了在毫微微蜂窝网络(femtocell network,FN)中,协同双小区系统的非正交多址接入(non-orthogonal multiple access,NOMA)与无线携能通信(simultaneous wireless information and power transfer,SWIPT)下行协作通信的中断性能,...本文研究了在毫微微蜂窝网络(femtocell network,FN)中,协同双小区系统的非正交多址接入(non-orthogonal multiple access,NOMA)与无线携能通信(simultaneous wireless information and power transfer,SWIPT)下行协作通信的中断性能,提出了一种边缘用户在邻基站及源基站随机中心用户共同协作的下行接入方案。所提方案共分为两个时隙:第一时隙内由两基站向所有用户广播叠加信号,提供中继服务的中心用户对其所接收的叠加信号逐级解码并收集能量。第二时隙,中心用户将其第一时隙内所收集的能量作为额外功率资源,在优先保证自身通信质量的前提下对成功解码的边缘用户信息进行再编码转发。基于空间均质泊松点过程(Poisson point process,PPP)中心用户的位置模型,推导了中心用户与边缘用户平均中断概率的表达式,进行了蒙特卡罗仿真验证,同时分析了各仿真参数(中心用户分布半径、用户阈值速率、路径损耗指数等)与中心用户、边缘用户平均中断概率的关系。结果表明:所提方案可以改善边缘用户的下行接入中断性能和系统吞吐量。展开更多
为了探求影响电力通信系统数据安全传输的关键因素,构建基于解码转发(decode-and-forward,DF)中继和非正交多址接入(non-orthogonal multiple access,NOMA)技术辅助的电力线通信(power line communication,PLC)系统,并研究其安全传输性...为了探求影响电力通信系统数据安全传输的关键因素,构建基于解码转发(decode-and-forward,DF)中继和非正交多址接入(non-orthogonal multiple access,NOMA)技术辅助的电力线通信(power line communication,PLC)系统,并研究其安全传输性能.针对外部窃听和内部窃听两种情况,联合考虑背景噪声和脉冲噪声的影响,分析系统的可达速率、遍历安全速率和安全中断概率等性能,并利用高斯-切比雪夫求积方法获得其相应的闭合表达式.结果表明:较高的脉冲噪声会降低系统的频谱效率和安全传输性能;功率分配系数以及源用户到中继用户的距离均对系统安全传输产生显著影响.进一步地,通过蒙特卡罗仿真实验验证了理论分析的正确性.展开更多
A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous...A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.展开更多
The two-dimensional non-Newtonian steady flow on a power-law stretched surface with suction or injection is studied. Thermal conductivity is assumed to vary as a linear function of temperature. The transformed governi...The two-dimensional non-Newtonian steady flow on a power-law stretched surface with suction or injection is studied. Thermal conductivity is assumed to vary as a linear function of temperature. The transformed governing equations in the present study are solved numerically using the Runge-Kutta method. Through a comparison, results for a special case of the problem show excellent agreement with those in a previous work. Two cases are considered, one corresponding to a cooled surface temperature and the other to a uniform surface temperature. Numerical results show that the thermal conductivity variation parameter, the injection parameter, and the power-law index have significant influences on the temperature profiles and the Nusselt number.展开更多
In order to better accommodate heterogeneous quality of service (QoS) in wireless networks, an algorithm called QoS-aware power and admission controls (QAPAC) is proposed. The system is modeled as a non-cooperative ga...In order to better accommodate heterogeneous quality of service (QoS) in wireless networks, an algorithm called QoS-aware power and admission controls (QAPAC) is proposed. The system is modeled as a non-cooperative game where the users adjust their transmit powers to maximize the utility, thus restraining the interferences. By using adaptive utility functions and tunable pricing parameters according to QoS levels, this algorithm can well meet different QoS requirements and improve system capacity compared with those that ignore the QoS differences.展开更多
The characteristics of low frequency electrical noise, voltage current ( V I ) and electrical derivation for 980 nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditi...The characteristics of low frequency electrical noise, voltage current ( V I ) and electrical derivation for 980 nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low frequency electrical noise with surface non radiative current of devices is discussed. The results indicate the low frequency electrical noise of 980 nm DQWLs with high power is mainly 1/ f noise and has good relation with the device surface current at low injection.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFB2604600).
文摘Vibration measurements can be used to evaluate the operation status of power equipment and are widely applied in equipment quality inspection and fault identification.Event-sensing technology can sense the change in surface light intensity caused by object vibration and provide a visual description of vibration behavior.Based on the analysis of the principle underlying the transformation of vibration behavior into event flow data by an event sensor,this paper proposes an algorithm to reconstruct event flow data into a relationship correlating vibration displacement and time to extract the amplitude-frequency characteristics of the vibration signal.A vibration measurement test platform is constructed,and feasibility and effectiveness tests are performed for the vibration motor and other power equipment.The results show that event-sensing technology can effectively perceive the surface vibration behavior of power and provide a wide dynamic range.Furthermore,the vibration measurement and visualization algorithm for power equipment constructed using this technology offers high measurement accuracy and efficiency.The results of this study provide a new noncontact and visual method for locating vibrations and performing amplitude-frequency analysis on power equipment.
文摘无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进行信息解码的同时收集能量,与无小区大规模MIMO-NOMA优势互补。文中基于SWIPT研究无小区大规模MIMO-NOMA系统中的能量效率问题,通过联合优化功率分配系数和SWIPT的时隙切换(Time Switching,TS)系数,提高系统的能量效率。为了最大化能量效率,采用布谷鸟算法设计功率分配系数。考虑一种特殊情况,将所有终端的TS系数设置相同,进而推导了最佳TS系数的封闭表达式。仿真结果表明,相较于几种已有方案,文中提出的优化方案可以显著提升系统的能量效率。
文摘In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater,the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching,the non-powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process,and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.
文摘980 nm InGaAs/GaAs separate confinement heterostructure (SCH) strained quantum well (QW) laser with non-absorbing facets was fabricated by using thermal treatment. Microchannel coolers with a five-layer thin oxygen-free copper plate structure were designed and fabricated through thermal bonding in hydrogen ambient. The highest CW (continuous wave) output power of 200 W for 5-bar arrays packaged by microchannel coolers was presented.
文摘本文研究了在毫微微蜂窝网络(femtocell network,FN)中,协同双小区系统的非正交多址接入(non-orthogonal multiple access,NOMA)与无线携能通信(simultaneous wireless information and power transfer,SWIPT)下行协作通信的中断性能,提出了一种边缘用户在邻基站及源基站随机中心用户共同协作的下行接入方案。所提方案共分为两个时隙:第一时隙内由两基站向所有用户广播叠加信号,提供中继服务的中心用户对其所接收的叠加信号逐级解码并收集能量。第二时隙,中心用户将其第一时隙内所收集的能量作为额外功率资源,在优先保证自身通信质量的前提下对成功解码的边缘用户信息进行再编码转发。基于空间均质泊松点过程(Poisson point process,PPP)中心用户的位置模型,推导了中心用户与边缘用户平均中断概率的表达式,进行了蒙特卡罗仿真验证,同时分析了各仿真参数(中心用户分布半径、用户阈值速率、路径损耗指数等)与中心用户、边缘用户平均中断概率的关系。结果表明:所提方案可以改善边缘用户的下行接入中断性能和系统吞吐量。
文摘为了探求影响电力通信系统数据安全传输的关键因素,构建基于解码转发(decode-and-forward,DF)中继和非正交多址接入(non-orthogonal multiple access,NOMA)技术辅助的电力线通信(power line communication,PLC)系统,并研究其安全传输性能.针对外部窃听和内部窃听两种情况,联合考虑背景噪声和脉冲噪声的影响,分析系统的可达速率、遍历安全速率和安全中断概率等性能,并利用高斯-切比雪夫求积方法获得其相应的闭合表达式.结果表明:较高的脉冲噪声会降低系统的频谱效率和安全传输性能;功率分配系数以及源用户到中继用户的距离均对系统安全传输产生显著影响.进一步地,通过蒙特卡罗仿真实验验证了理论分析的正确性.
基金Project(JC200903180555A) supported by Shenzhen City Science and Technology Plan, China
文摘A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.
文摘The two-dimensional non-Newtonian steady flow on a power-law stretched surface with suction or injection is studied. Thermal conductivity is assumed to vary as a linear function of temperature. The transformed governing equations in the present study are solved numerically using the Runge-Kutta method. Through a comparison, results for a special case of the problem show excellent agreement with those in a previous work. Two cases are considered, one corresponding to a cooled surface temperature and the other to a uniform surface temperature. Numerical results show that the thermal conductivity variation parameter, the injection parameter, and the power-law index have significant influences on the temperature profiles and the Nusselt number.
基金the National Natural Science Foundation of China (No.60372055)the National Doctoral Foundation of China (No.20030698027)
文摘In order to better accommodate heterogeneous quality of service (QoS) in wireless networks, an algorithm called QoS-aware power and admission controls (QAPAC) is proposed. The system is modeled as a non-cooperative game where the users adjust their transmit powers to maximize the utility, thus restraining the interferences. By using adaptive utility functions and tunable pricing parameters according to QoS levels, this algorithm can well meet different QoS requirements and improve system capacity compared with those that ignore the QoS differences.
文摘The characteristics of low frequency electrical noise, voltage current ( V I ) and electrical derivation for 980 nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low frequency electrical noise with surface non radiative current of devices is discussed. The results indicate the low frequency electrical noise of 980 nm DQWLs with high power is mainly 1/ f noise and has good relation with the device surface current at low injection.