The sampling process is very inefficient for sam-pling-based motion planning algorithms that excess random sam-ples are generated in the planning space.In this paper,we pro-pose an adaptive space expansion(ASE)approac...The sampling process is very inefficient for sam-pling-based motion planning algorithms that excess random sam-ples are generated in the planning space.In this paper,we pro-pose an adaptive space expansion(ASE)approach which belongs to the informed sampling category to improve the sampling effi-ciency for quickly finding a feasible path.The ASE method enlarges the search space gradually and restrains the sampling process in a sequence of small hyper-ellipsoid ring subsets to avoid exploring the unnecessary space.Specifically,for a con-structed small hyper-ellipsoid ring subset,if the algorithm cannot find a feasible path in it,then the subset is expanded.Thus,the ASE method successively does space exploring and space expan-sion until the final path has been found.Besides,we present a particular construction method of the hyper-ellipsoid ring that uniform random samples can be directly generated in it.At last,we present a feasible motion planner BiASE and an asymptoti-cally optimal motion planner BiASE*using the bidirectional exploring method and the ASE strategy.Simulations demon-strate that the computation speed is much faster than that of the state-of-the-art algorithms.The source codes are available at https://github.com/shshlei/ompl.展开更多
The South China Sea suffers strongly from the typhoon storm surge disasters in China,and its northern coastal areas are facing severe risks.Therefore,it is necessary and urgent to establish an assessment system for ra...The South China Sea suffers strongly from the typhoon storm surge disasters in China,and its northern coastal areas are facing severe risks.Therefore,it is necessary and urgent to establish an assessment system for rating typhoon storm surge disaster.We constructed an effective and reliable rating assessment system for typhoon storm surge disaster based on the theories of over-threshold,distribution function family,and composite extreme value.The over-threshold sample was used as the basis of data analysis,the composite extreme value expansion model was used to derive the design water increment,and then the disaster level was delineated based on the return period level.The results of the extreme value model comparison show that the Weibull-Pareto distribution is more suitable than the classical extreme value distribution for fitting the over-threshold samples.The results of the return period projection are relatively stable based on different analysis samples.Taking the 10 typhoon storm surges as examples,they caused landfall in the Guangdong area in the past 10 years.The results of the assessment ranking indicate that the risk levels based on the return period levels obtained from different distributions are generally consistent.When classifying low-risk areas,the classification criteria of the State Oceanic Administration,China(SOA,2012)are more conservative.In the high-risk areas,the results of the assessment ranking based on return period are more consistent with those of the SOA.展开更多
本文提出了一种基于时间拓展方式的实时采样接收算法.该算法利用DTC (digital to time converter)产生两组相位可控的方波信号分别控制基带信号的发射和接收ADC (analog to digital converter)的采样,这两组方波信号之间的相位差为等差...本文提出了一种基于时间拓展方式的实时采样接收算法.该算法利用DTC (digital to time converter)产生两组相位可控的方波信号分别控制基带信号的发射和接收ADC (analog to digital converter)的采样,这两组方波信号之间的相位差为等差数列,通过调整锁相环的倍频比与输入信号的参考频率使其最小相位差为62 ps,从而完成低频ADC (1 MHz)对高频信号的等效采样,由此大大降低系统的功耗和硬件系统的设计难度,增加系统的可维护性.利用Verilog HDL在FPGA (field programmable gate array)上实现了该算法,并完成验证.展开更多
The rapid variation of channel can induce the intercarrier interference in orthogonal frequency-division multiplexing （OFDM） systems. Intercarrier interference will significantly increase the difficulty of OFDM chan...The rapid variation of channel can induce the intercarrier interference in orthogonal frequency-division multiplexing （OFDM） systems. Intercarrier interference will significantly increase the difficulty of OFDM channel estimation because too many channel coefficients need be estimated. In this article, a novel channel estimator is proposed to resolve the above problem. This estimator consists of two parts： the channel parameter estimation unit （CPEU）, which is used to estimate the number of channel taps and the multipath time delays, and the channel coefficient estimation unit （CCEU）, which is used to estimate the channel coefficients by using the estimated channel parameters provided by CPEU. In CCEU, the over-sampling basis expansion model is resorted to solve the problem that a large number of channel coefficients need to be estimated. Finally, simulation results are given to scale the performance of the proposed scheme.展开更多
家用及商用空调智能功率模块(Intelligent Power Module,IPM)-FO功能保护直接决定了驱动电机乃至整个系统的稳定运行,而智能功率模块出现FO保护可能是由于印刷电路板(Printed Circuit Board,PCB)布局不合理、驱动控制器存在的强弱电干...家用及商用空调智能功率模块(Intelligent Power Module,IPM)-FO功能保护直接决定了驱动电机乃至整个系统的稳定运行,而智能功率模块出现FO保护可能是由于印刷电路板(Printed Circuit Board,PCB)布局不合理、驱动控制器存在的强弱电干扰、热地冷地之间的波动、开关电源变压器开关动作干扰、电子膨胀阀动作导致地线扰动影响电机电流采样等诸多因素。因此,驱动板FO出现保护时首先需要从IPM-FO模块保护机理出发,采用试验排除法逐步确认故障点。采用所提试验技术方法逐步排查直至整机正常运行,通过整改前后波形对比,进一步证明采用该方法能有效解决专用智能功率模块出现的FO问题,对空调行业售后技术服务人员有一定的的借签及指导意义。展开更多
基金supported in part by the National Natural Science Foun-dation of China(51975236)the National Key Research and Development Program of China(2018YFA0703203)the Innovation Project of Optics Valley Laboratory(OVL2021BG007)。
文摘The sampling process is very inefficient for sam-pling-based motion planning algorithms that excess random sam-ples are generated in the planning space.In this paper,we pro-pose an adaptive space expansion(ASE)approach which belongs to the informed sampling category to improve the sampling effi-ciency for quickly finding a feasible path.The ASE method enlarges the search space gradually and restrains the sampling process in a sequence of small hyper-ellipsoid ring subsets to avoid exploring the unnecessary space.Specifically,for a con-structed small hyper-ellipsoid ring subset,if the algorithm cannot find a feasible path in it,then the subset is expanded.Thus,the ASE method successively does space exploring and space expan-sion until the final path has been found.Besides,we present a particular construction method of the hyper-ellipsoid ring that uniform random samples can be directly generated in it.At last,we present a feasible motion planner BiASE and an asymptoti-cally optimal motion planner BiASE*using the bidirectional exploring method and the ASE strategy.Simulations demon-strate that the computation speed is much faster than that of the state-of-the-art algorithms.The source codes are available at https://github.com/shshlei/ompl.
基金Supported by the National Natural Science Foundation of China(Nos.52071306,52101360)the Natural Science Foundation of Shandong Province(No.ZR2019MEE050)the State Key Laboratory of Coastal and Offshore Engineering(No.LP2104)。
文摘The South China Sea suffers strongly from the typhoon storm surge disasters in China,and its northern coastal areas are facing severe risks.Therefore,it is necessary and urgent to establish an assessment system for rating typhoon storm surge disaster.We constructed an effective and reliable rating assessment system for typhoon storm surge disaster based on the theories of over-threshold,distribution function family,and composite extreme value.The over-threshold sample was used as the basis of data analysis,the composite extreme value expansion model was used to derive the design water increment,and then the disaster level was delineated based on the return period level.The results of the extreme value model comparison show that the Weibull-Pareto distribution is more suitable than the classical extreme value distribution for fitting the over-threshold samples.The results of the return period projection are relatively stable based on different analysis samples.Taking the 10 typhoon storm surges as examples,they caused landfall in the Guangdong area in the past 10 years.The results of the assessment ranking indicate that the risk levels based on the return period levels obtained from different distributions are generally consistent.When classifying low-risk areas,the classification criteria of the State Oceanic Administration,China(SOA,2012)are more conservative.In the high-risk areas,the results of the assessment ranking based on return period are more consistent with those of the SOA.
文摘本文提出了一种基于时间拓展方式的实时采样接收算法.该算法利用DTC (digital to time converter)产生两组相位可控的方波信号分别控制基带信号的发射和接收ADC (analog to digital converter)的采样,这两组方波信号之间的相位差为等差数列,通过调整锁相环的倍频比与输入信号的参考频率使其最小相位差为62 ps,从而完成低频ADC (1 MHz)对高频信号的等效采样,由此大大降低系统的功耗和硬件系统的设计难度,增加系统的可维护性.利用Verilog HDL在FPGA (field programmable gate array)上实现了该算法,并完成验证.
文摘The rapid variation of channel can induce the intercarrier interference in orthogonal frequency-division multiplexing （OFDM） systems. Intercarrier interference will significantly increase the difficulty of OFDM channel estimation because too many channel coefficients need be estimated. In this article, a novel channel estimator is proposed to resolve the above problem. This estimator consists of two parts： the channel parameter estimation unit （CPEU）, which is used to estimate the number of channel taps and the multipath time delays, and the channel coefficient estimation unit （CCEU）, which is used to estimate the channel coefficients by using the estimated channel parameters provided by CPEU. In CCEU, the over-sampling basis expansion model is resorted to solve the problem that a large number of channel coefficients need to be estimated. Finally, simulation results are given to scale the performance of the proposed scheme.
文摘家用及商用空调智能功率模块(Intelligent Power Module,IPM)-FO功能保护直接决定了驱动电机乃至整个系统的稳定运行,而智能功率模块出现FO保护可能是由于印刷电路板(Printed Circuit Board,PCB)布局不合理、驱动控制器存在的强弱电干扰、热地冷地之间的波动、开关电源变压器开关动作干扰、电子膨胀阀动作导致地线扰动影响电机电流采样等诸多因素。因此,驱动板FO出现保护时首先需要从IPM-FO模块保护机理出发,采用试验排除法逐步确认故障点。采用所提试验技术方法逐步排查直至整机正常运行,通过整改前后波形对比,进一步证明采用该方法能有效解决专用智能功率模块出现的FO问题,对空调行业售后技术服务人员有一定的的借签及指导意义。
