针对正交频分线性调频(OFD-LFM)信号MIMO高分辨雷达稀疏成像问题展开研究,在分析了OFD-LFM信号频谱合成原理以及MIMO高分辨雷达一次快拍成像原理的基础上,给出了一种基于频域稀疏OFD-LFM信号和空域稀疏MIMO雷达天线阵列的联合稀疏模型,...针对正交频分线性调频(OFD-LFM)信号MIMO高分辨雷达稀疏成像问题展开研究,在分析了OFD-LFM信号频谱合成原理以及MIMO高分辨雷达一次快拍成像原理的基础上,给出了一种基于频域稀疏OFD-LFM信号和空域稀疏MIMO雷达天线阵列的联合稀疏模型,并结合压缩感知理论,提出了目标高分辨距离像(high-resolution range profile,HRRP)合成方法以及目标二维成像方法。该方法能够在大幅减少OFD-LFM信号子载波个数、大幅减少MIMO高分辨雷达天线阵元个数的条件下,利用一次快拍重构出高质量的目标HRRP和二维像,不仅避免了目标机动带来的运动补偿难题,同时还有利于天线阵列的工程实现。仿真结果表明所提方法是有效的,且具有一定的抗噪性。展开更多
As a promising paradigm of the fifth generation networks,fog radio access network(F-RAN)has attracted lots of attention nowadays.To fully utilize the promising gain of F-RANs,the acquisition of accurate channel state ...As a promising paradigm of the fifth generation networks,fog radio access network(F-RAN)has attracted lots of attention nowadays.To fully utilize the promising gain of F-RANs,the acquisition of accurate channel state information is significant.However,conventional channel estimation approaches are not suitable in F-RANs due to the large training and feedback overhead.In this paper,we consider the channel estimation in F-RANs with fog access point(F-AP)equipped with massive antennas.Thanks to the computing ability of F-AP and the sparsity of channel matrices in angular domain,Gated Recurrent Unit(GRU),a data-driven based channel estimation is proposed at F-AP to reduce the training and feedback overhead.The GRU-based method can capture the hidden sparsity structure automatically through the network training.Moreover,to further improve the channel estimation,a bidirectional GRU based method is proposed,whose target channel structure is decided by previous and subsequent structures.We compare the performance of our proposed channel estimation with traditional methods(Orthogonal Matching Pursuit(OMP)and Simultaneous OMP(SOMP)).Simulation results show that the proposed approaches have better performance compared with the traditional OMP and SOMP methods.展开更多
In the recent decades, effects of blast loads on natural and man-made structures have gained considerable attention due to increase in threat from various man-made activities. Site-specific empirical relationships for...In the recent decades, effects of blast loads on natural and man-made structures have gained considerable attention due to increase in threat from various man-made activities. Site-specific empirical relationships for calculation of blast-induced vibration parameters like peak particle velocity （PPV） and peak particle displacement （PPD） are commonly used for estimation of blast loads in design. However, these relation- ships are not able to consider the variation in rock parameters and uncertainty of in situ conditions. In this paper, a total of 1089 published blast data of various researchers in different rock sites have been collected and used to propose generalized empirical model for PPV by considering the effects of rock parameters like unit weight, rock quality designation （ROD）, geological strength index （GSI）, and uniaxial compressive strength （UCS）. The proposed PPV model has a good correlation coefficient and hence it can be directly used in prediction of blast-induced vibrations in rocks. Standard errors and coefficient of correlations of the predicted blast-induced vibration parameters are obtained with respect to the observed field data. The proposed empirical model for PPV has also been compared with the empirical models available for blast vibrations predictions given by other researchers and found to be in good agreement with specific cases.展开更多
针对大尺度压缩感知重构算法实时性应用的需要,探讨了基于图形处理器(GPU)的正交匹配追踪算法(OMP)的加速方法及实现。为降低中央处理器与GPU之间传输的高延迟,将整个OMP算法的迭代过程转移到GPU上并行执行。其中,在GPU端根据全局存储...针对大尺度压缩感知重构算法实时性应用的需要,探讨了基于图形处理器(GPU)的正交匹配追踪算法(OMP)的加速方法及实现。为降低中央处理器与GPU之间传输的高延迟,将整个OMP算法的迭代过程转移到GPU上并行执行。其中,在GPU端根据全局存储器的访问特点,改进CUDA程序使存储访问满足合并访问条件,降低访问延迟。同时,根据流多处理器(SM)的资源条件,增加SM中共享存储器的分配,通过改进线程访问算法来降低bank conflict,提高访存速度。在NVIDIA Tesla K20Xm GPU和Intel(R)E5-2650CPU上进行了测试,结果表明,算法中耗时长的投影模块、更新权值模块分别可获得32和46倍的加速比,算法整体可获得34倍的加速比。展开更多
针对压缩感知重构算法计算实时性太差的问题,提出压缩采样追踪匹配(compressive sampling matching pursuit,Co Sa M P)算法的并行化加速算法。基于多线程技术实现重构算法的粗粒度并行化,分析Co Sa M P算法的计算热点,将其中耗时较多...针对压缩感知重构算法计算实时性太差的问题,提出压缩采样追踪匹配(compressive sampling matching pursuit,Co Sa M P)算法的并行化加速算法。基于多线程技术实现重构算法的粗粒度并行化,分析Co Sa M P算法的计算热点,将其中耗时较多的矩阵操作移植在图形处理器(graphics processing unit,GPU)上,实现算法的细粒度并行化。在测试图像上进行试验,结果表明:并行化加速算法取得50倍的加速效果,有效地降低重构算法的计算时间开销。展开更多
文摘针对正交频分线性调频(OFD-LFM)信号MIMO高分辨雷达稀疏成像问题展开研究,在分析了OFD-LFM信号频谱合成原理以及MIMO高分辨雷达一次快拍成像原理的基础上,给出了一种基于频域稀疏OFD-LFM信号和空域稀疏MIMO雷达天线阵列的联合稀疏模型,并结合压缩感知理论,提出了目标高分辨距离像(high-resolution range profile,HRRP)合成方法以及目标二维成像方法。该方法能够在大幅减少OFD-LFM信号子载波个数、大幅减少MIMO高分辨雷达天线阵元个数的条件下,利用一次快拍重构出高质量的目标HRRP和二维像,不仅避免了目标机动带来的运动补偿难题,同时还有利于天线阵列的工程实现。仿真结果表明所提方法是有效的,且具有一定的抗噪性。
基金supported in part by the State Major Science and Technology Special Project(Grant No.2018ZX03001023)the National Natural Science Foundation of China under No.61831002+1 种基金the National Science Foundation for Postdoctoral Scientists of China(Grant No.2018M641279)FundamentalResearch Funds for the Central Universities under Grant No.2018XKJC01
文摘As a promising paradigm of the fifth generation networks,fog radio access network(F-RAN)has attracted lots of attention nowadays.To fully utilize the promising gain of F-RANs,the acquisition of accurate channel state information is significant.However,conventional channel estimation approaches are not suitable in F-RANs due to the large training and feedback overhead.In this paper,we consider the channel estimation in F-RANs with fog access point(F-AP)equipped with massive antennas.Thanks to the computing ability of F-AP and the sparsity of channel matrices in angular domain,Gated Recurrent Unit(GRU),a data-driven based channel estimation is proposed at F-AP to reduce the training and feedback overhead.The GRU-based method can capture the hidden sparsity structure automatically through the network training.Moreover,to further improve the channel estimation,a bidirectional GRU based method is proposed,whose target channel structure is decided by previous and subsequent structures.We compare the performance of our proposed channel estimation with traditional methods(Orthogonal Matching Pursuit(OMP)and Simultaneous OMP(SOMP)).Simulation results show that the proposed approaches have better performance compared with the traditional OMP and SOMP methods.
文摘In the recent decades, effects of blast loads on natural and man-made structures have gained considerable attention due to increase in threat from various man-made activities. Site-specific empirical relationships for calculation of blast-induced vibration parameters like peak particle velocity （PPV） and peak particle displacement （PPD） are commonly used for estimation of blast loads in design. However, these relation- ships are not able to consider the variation in rock parameters and uncertainty of in situ conditions. In this paper, a total of 1089 published blast data of various researchers in different rock sites have been collected and used to propose generalized empirical model for PPV by considering the effects of rock parameters like unit weight, rock quality designation （ROD）, geological strength index （GSI）, and uniaxial compressive strength （UCS）. The proposed PPV model has a good correlation coefficient and hence it can be directly used in prediction of blast-induced vibrations in rocks. Standard errors and coefficient of correlations of the predicted blast-induced vibration parameters are obtained with respect to the observed field data. The proposed empirical model for PPV has also been compared with the empirical models available for blast vibrations predictions given by other researchers and found to be in good agreement with specific cases.
文摘针对大尺度压缩感知重构算法实时性应用的需要,探讨了基于图形处理器(GPU)的正交匹配追踪算法(OMP)的加速方法及实现。为降低中央处理器与GPU之间传输的高延迟,将整个OMP算法的迭代过程转移到GPU上并行执行。其中,在GPU端根据全局存储器的访问特点,改进CUDA程序使存储访问满足合并访问条件,降低访问延迟。同时,根据流多处理器(SM)的资源条件,增加SM中共享存储器的分配,通过改进线程访问算法来降低bank conflict,提高访存速度。在NVIDIA Tesla K20Xm GPU和Intel(R)E5-2650CPU上进行了测试,结果表明,算法中耗时长的投影模块、更新权值模块分别可获得32和46倍的加速比,算法整体可获得34倍的加速比。
文摘目的探究基于光梭成像(United Compressed Sensing,uCS)技术的多动脉期成像在肝脏磁共振增强检查中的成像特点和应用价值。方法选取经我院临床诊断为肝脏实质性占位患者42例为研究对象,应用uCS技术进行肝脏多动脉期扫描。对所得多组动脉期图像(uCS组)与基于平行成像(parallel Imaging,PI)单动脉期图像(PI组)进行分析。并对2组图像伪影、信噪比(Signal to Noise Ratio,SNR)、肝脏信号变异系数(Coefficient of Variation,CV)和病灶强化效果进行综合评测。结果uCS组动脉晚期的图像质量综合评测优于PI组:伪影评分为(3.81±0.45)分vs.(3.19±0.94)分(P<0.05);右肝图像SNR为(244.87±62.66)vs.(191.19±51.13)(P<0.05);右肝图像变异系数优于PI组[(0.045±0.010)vs.(0.051±0.011)](P<0.05),并可动态显示病灶连续强化过程。结论基于uCS技术的多期动脉成像能应用于肝脏增强磁共振扫描,可以在保证图像质量的同时减少动脉期伪影、优化动脉期时相和提供更丰富的肿瘤血管信息。
文摘针对压缩感知重构算法计算实时性太差的问题,提出压缩采样追踪匹配(compressive sampling matching pursuit,Co Sa M P)算法的并行化加速算法。基于多线程技术实现重构算法的粗粒度并行化,分析Co Sa M P算法的计算热点,将其中耗时较多的矩阵操作移植在图形处理器(graphics processing unit,GPU)上,实现算法的细粒度并行化。在测试图像上进行试验,结果表明:并行化加速算法取得50倍的加速效果,有效地降低重构算法的计算时间开销。
