A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, ...A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment.展开更多
According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the ...According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s.展开更多
A PV （photovoltaic） solar panels exhibit non-linear current--voltage characteristics, and according to the MPT （maximum power transform） theory, it can produce maximum power at only one particular OP （operating p...A PV （photovoltaic） solar panels exhibit non-linear current--voltage characteristics, and according to the MPT （maximum power transform） theory, it can produce maximum power at only one particular OP （operating point）; namely, when the source impedance matches with the load impedance, a match which cannot be guaranteed spontaneously. Furthermore, the MPP （maximum power point） changes with temperature and light intensity variations. Therefore, different algorithms have been developed for finding MPPT （maximum power point tracking） based on offline and online methods. Evaluating the performance of these algorithms for various PV systems operating under highly dynamic environments are essentials to ensure producing reliable, efficient, cost-effective and high performance systems. One possible approach for system evaluation is to use computer simulation. This paper addresses the use of Matlab software as a simulation tool for evaluating the performance of PV solar systems and finding the MPPT.展开更多
The mobility of relay has great influence on the performance of a cooperative relay system.This paper proposes a dynamic selection scheme under the amplify-and-forward communication mode in high mobility environment,b...The mobility of relay has great influence on the performance of a cooperative relay system.This paper proposes a dynamic selection scheme under the amplify-and-forward communication mode in high mobility environment,based on the estimation of channels and the power allocation for each relay node by comparing it with the pre-set threshold.This scheme is used to choose the cooperative relay dynamically for a multiple relay scenario.Simulation results show that this proposed relay selection scheme decreases the outage probability effectively,maintains system capacity well,and improves the performance of the relay system.展开更多
文摘A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment.
基金supported by the Youth Science Fund,National Natural Science Foundation of China under Grant No.61102130
文摘According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s.
文摘A PV （photovoltaic） solar panels exhibit non-linear current--voltage characteristics, and according to the MPT （maximum power transform） theory, it can produce maximum power at only one particular OP （operating point）; namely, when the source impedance matches with the load impedance, a match which cannot be guaranteed spontaneously. Furthermore, the MPP （maximum power point） changes with temperature and light intensity variations. Therefore, different algorithms have been developed for finding MPPT （maximum power point tracking） based on offline and online methods. Evaluating the performance of these algorithms for various PV systems operating under highly dynamic environments are essentials to ensure producing reliable, efficient, cost-effective and high performance systems. One possible approach for system evaluation is to use computer simulation. This paper addresses the use of Matlab software as a simulation tool for evaluating the performance of PV solar systems and finding the MPPT.
基金Supported by the National Natural Science Foundation of China(No.61172073)the State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University(No.RCS2011ZT003)+2 种基金the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University(No.2012D19)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(No.2013JBZ001)the Program for New Century Excellent Talents in University of Ministry of Education of China(No.NCET-12-0766)
文摘The mobility of relay has great influence on the performance of a cooperative relay system.This paper proposes a dynamic selection scheme under the amplify-and-forward communication mode in high mobility environment,based on the estimation of channels and the power allocation for each relay node by comparing it with the pre-set threshold.This scheme is used to choose the cooperative relay dynamically for a multiple relay scenario.Simulation results show that this proposed relay selection scheme decreases the outage probability effectively,maintains system capacity well,and improves the performance of the relay system.
