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Parameter estimation of maneuvering targets in OTHR based on sparse time-frequency representation 被引量:2
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作者 Jinfeng Hu Xuan He +3 位作者 Wange Li Hui Ai Huiyong Li Julan Xie 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第3期574-580,共7页
This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar(OTHR). In this method, the sparse time-frequency distribution o... This paper proposes a new method for estimating the parameter of maneuvering targets based on sparse time-frequency transform in over-the-horizon radar(OTHR). In this method, the sparse time-frequency distribution of the radar echo is obtained by solving a sparse optimization problem based on the short-time Fourier transform. Then Hough transform is employed to estimate the parameter of the targets. The proposed algorithm has the following advantages: Compared with the Wigner-Hough transform method, the computational complexity of the sparse optimization is low due to the application of fast Fourier transform(FFT). And the computational cost of Hough transform is also greatly reduced because of the sparsity of the time-frequency distribution. Compared with the high order ambiguity function(HAF) method, the proposed method improves in terms of precision and robustness to noise. Simulation results show that compared with the HAF method, the required SNR and relative mean square error are 8 dB lower and 50 dB lower respectively in the proposed method. While processing the field experiment data, the execution time of Hough transform in the proposed method is only 4% of the Wigner-Hough transform method. 展开更多
关键词 over-the-horizon radar(OTHR) maneuvering tar-get parameter estimation sparse time-frequency transform Hough transform
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Joint 2D DOA and Doppler frequency estimation for L-shaped array using compressive sensing 被引量:6
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作者 WANG Shixin ZHAO Yuan +3 位作者 LAILA Ibrahim XIONG Ying WANG Jun TANG Bin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第1期28-36,共9页
A joint two-dimensional(2D)direction-of-arrival(DOA)and radial Doppler frequency estimation method for the L-shaped array is proposed in this paper based on the compressive sensing(CS)framework.Revised from the conven... A joint two-dimensional(2D)direction-of-arrival(DOA)and radial Doppler frequency estimation method for the L-shaped array is proposed in this paper based on the compressive sensing(CS)framework.Revised from the conventional CS-based methods where the joint spatial-temporal parameters are characterized in one large scale matrix,three smaller scale matrices with independent azimuth,elevation and Doppler frequency are introduced adopting a separable observation model.Afterwards,the estimation is achieved by L1-norm minimization and the Bayesian CS algorithm.In addition,under the L-shaped array topology,the azimuth and elevation are separated yet coupled to the same radial Doppler frequency.Hence,the pair matching problem is solved with the aid of the radial Doppler frequency.Finally,numerical simulations corroborate the feasibility and validity of the proposed algorithm. 展开更多
关键词 electronic warfare L-shaped array joint parameter estimation L1-norm minimization Bayesian compressive sensing(CS) pair matching
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Adaptive target and jamming recognition for the pulse doppler radar fuze based on a time-frequency joint feature and an online-updated naive bayesian classifier with minimal risk 被引量:9
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作者 Jian Dai Xin-hong Hao +2 位作者 Ze Li Ping Li Xiao-peng Yan 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第3期457-466,共10页
This paper considers the problem of target and jamming recognition for the pulse Doppler radar fuze(PDRF).To solve the problem,the matched filter outputs of the PDRF under the action of target and jamming are analyzed... This paper considers the problem of target and jamming recognition for the pulse Doppler radar fuze(PDRF).To solve the problem,the matched filter outputs of the PDRF under the action of target and jamming are analyzed.Then,the frequency entropy and peak-to-peak ratio are extracted from the matched filter output of the PDRF,and the time-frequency joint feature is constructed.Based on the time-frequency joint feature,the naive Bayesian classifier(NBC)with minimal risk is established for target and jamming recognition.To improve the adaptability of the proposed method in complex environments,an online update process that adaptively modifies the classifier in the duration of the work of the PDRF is proposed.The experiments show that the PDRF can maintain high recognition accuracy when the signal-to-noise ratio(SNR)decreases and the jamming-to-signal ratio(JSR)increases.Moreover,the applicable analysis shows that he ONBCMR method has low computational complexity and can fully meet the real-time requirements of PDRF. 展开更多
关键词 Pulse Doppler radar fuze(PDRF) Target and jamming recognition time-frequency joint feature Online-update naive Bayesian classifier minimal risk(ONBCMR)
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Cramer-Rao bound of joint estimation of target location and velocity for coherent MIMO radar 被引量:3
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作者 Peilin Sun Jun Tang Shuang Wan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第4期566-572,共7页
The optimal estimation performance of target parameters is studied. First, the general form of Cramer-Rao bound (CRB) for joint estimation of target location and velocity is derived for coherent multiple input multi... The optimal estimation performance of target parameters is studied. First, the general form of Cramer-Rao bound (CRB) for joint estimation of target location and velocity is derived for coherent multiple input multiple output (MIMO) radars. To gain some insight into the behavior of the CRB, the CRB with a set of given orthogonal waveforms is studied as a specific case. Second, a maximum likelihood (ML) estimation algorithm is proposed. The mean square error (MSE) of the ML estimation of target location and velocity is obtained by Monte Carlo simulation and it approaches CRB in the high signal-to-noise ratio (SNR) region. 展开更多
关键词 Cramer-Rao bound (CRB) joint estimation coherentmultiple input multiple output (MIMO) radar.
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ADC-GERT network parameter estimation model for mission effectiveness of joint operation system 被引量:6
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作者 FANG Zhigeng WU Shuang +1 位作者 ZHANG Xiaoli SUN Yunke 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第6期1394-1406,共13页
Effectiveness evaluation of the joint operation system is an important basis for the demonstration and development of weapon equipment.With the consideration that existing models of system effectiveness evaluation sel... Effectiveness evaluation of the joint operation system is an important basis for the demonstration and development of weapon equipment.With the consideration that existing models of system effectiveness evaluation seldom describe the structural relationship among equipment clearly as well as reflect the dynamic,the analog-to-digital converter-graphical evaluation and review technique(ADC-GERT)network parameter estimation model is proposed based on the ADC model and the joint operation system structure.Firstly,analysis of the joint operation system structure and operation process is conducted to build the GERT network,where equipment subsystems are nodes and activities are directed arches.Then the mission effectiveness of equipment subsystems is calculated by the ADC model.The probability transfer parameters are modified by the mission effectiveness of equipment subsystems based on the Bayesian theorem,with the ADC-GERT network parameter estimation model constructed.Finally,a case study is used to validate the efficiency and dynamic of the ADC-GERT network parameter estimation model. 展开更多
关键词 joint operation system system mission effectiveness analog-to-digital converter(ADC)model graphical evaluation and review technique(GERT) parameter estimation
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Joint synchronization estimation based on genetic algorithm for OFDM/OQAM systems 被引量:3
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作者 LIU Yongjin CHEN Xihong ZHAO Yu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第4期657-665,共9页
This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increas... This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increase the spectrum efficiency,an improved preamble structure without guard symbols is derived at first. On this basis, instead of deriving the log likelihood function of power spectral density, joint estimation of the symbol timing offset and carrier frequency offset based on the preamble proposed is formulated into a bivariate optimization problem. After that, an improved genetic algorithm is used to find its global optimum solution. Conclusions can be drawn from simulation results that the proposed method has advantages in the joint estimation of synchronization. 展开更多
关键词 offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) SYNCHRONIZATION joint estimation genetic algorithm
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Joint DOA and polarization estimation for unequal power sources based on reconstructed noise subspace 被引量:2
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作者 Yong Han Qingyuan Fang +2 位作者 Fenggang Yan Ming Jin Xiaolin Qiao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第3期501-513,共13页
In most literature about joint direction of arrival(DOA) and polarization estimation, the case that sources possess different power levels is seldom discussed. However, this case exists widely in practical applicati... In most literature about joint direction of arrival(DOA) and polarization estimation, the case that sources possess different power levels is seldom discussed. However, this case exists widely in practical applications, especially in passive radar systems. In this paper, we propose a joint DOA and polarization estimation method for unequal power sources based on the reconstructed noise subspace. The invariance property of noise subspace(IPNS) to power of sources has been proved an effective method to estimate DOA of unequal power sources. We develop the IPNS method for joint DOA and polarization estimation based on a dual polarized array. Moreover, we propose an improved IPNS method based on the reconstructed noise subspace, which has higher resolution probability than the IPNS method. It is theoretically proved that the IPNS to power of sources is still valid when the eigenvalues of the noise subspace are changed artificially. Simulation results show that the resolution probability of the proposed method is enhanced compared with the methods based on the IPNS and the polarimetric multiple signal classification(MUSIC) method. Meanwhile, the proposed method has approximately the same estimation accuracy as the IPNS method for the weak source. 展开更多
关键词 invariance property of noise subspace(IPNS) joint DOA and polarization estimation multiple signal classification(MUSIC) reconstruction of noise subspace unequal power sources
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A method of Robust low-angle target height and compound reflection coefficient joint estimation
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作者 WANG Shenghua CAO Yunhe LIU Yutao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第2期322-329,共8页
It is always a challenging issue for radar systems to estimate the height of a low-angle target in the multipath propagation environment.The highly deterministic maximum likelihood estimator has a high accuracy,but th... It is always a challenging issue for radar systems to estimate the height of a low-angle target in the multipath propagation environment.The highly deterministic maximum likelihood estimator has a high accuracy,but the errors of the ground reflection coefficient and the reflecting surface height have serious influence on the method.In this paper,a robust es-timation method with less computation burden is proposed based on the compound reflection coefficient multipath model for low-angle targets.The compound reflection coefficient is es-timated from the received data of the array and then a one-di-mension generalized steering vector is constructed to estimate the target height.The algorithm is robust to the reflecting sur-face height error and the ground reflection coefficient error.Fi-nally,the experiment and simulation results demonstrate the validity of the proposed method. 展开更多
关键词 low-angle target robust joint estimation compound reflection coefficient MULTIPATH direction of arrival(DOA)
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Research on LPI radar signal detection and parameter estimation technology 被引量:4
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作者 WAN Tao JIANG Kaili +2 位作者 LIAO Jingyi JIA Tingting TANG Bin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第3期566-572,共7页
Modern radar signals mostly use low probability of intercept(LPI)waveforms,which have short pulses in the time domain,multicomponent properties,frequency hopping,combined modulation waveforms and other characteristics... Modern radar signals mostly use low probability of intercept(LPI)waveforms,which have short pulses in the time domain,multicomponent properties,frequency hopping,combined modulation waveforms and other characteristics,making the detection and estimation of LPI radar signals extremely difficult,and leading to highly required significant research on perception technology in the battlefield environment.This paper proposes a visibility graphs(VG)-based multicomponent signals detection method and a modulation waveforms parameter estimation algorithm based on the time-frequency representation(TFR).On the one hand,the frequency domain VG is used to set the dynamic threshold for detecting the multicomponent LPI radar waveforms.On the other hand,the signal is projected into the time and frequency domains by the TFR method for estimating its symbol width and instantaneous frequency(IF).Simulation performance shows that,compared with the most advanced methods,the algorithm proposed in this paper has a valuable advantage.Meanwhile,the calculation cost of the algorithm is quite low,and it is achievable in the future battlefield. 展开更多
关键词 multicomponent signals detection parameter estimation visibility graphs(VG) low probability of intercept(LPI) time-frequency representation(TFR)
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Joint planning method for cross-domain unmanned swarm target assignment and mission trajectory
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作者 WANG Ning LIANG Xiaolong +2 位作者 LI Zhe HOU Yueqi YANG Aiwu 《Journal of Systems Engineering and Electronics》 2025年第3期736-753,共18页
Compared with single-domain unmanned swarms,cross-domain unmanned swarms continue to face new challenges in terms of platform performance and constraints.In this paper,a joint unmanned swarm target assignment and miss... Compared with single-domain unmanned swarms,cross-domain unmanned swarms continue to face new challenges in terms of platform performance and constraints.In this paper,a joint unmanned swarm target assignment and mission trajectory planning method is proposed to meet the requirements of cross-domain unmanned swarm mission planning.Firstly,the different performances of cross-domain heterogeneous platforms and mission requirements of targets are characterised by using a collection of operational resources.Secondly,an algorithmic framework for joint target assignment and mission trajectory planning is proposed,in which the initial planning of the trajectory is performed in the target assignment phase,while the trajectory is further optimised afterwards.Next,the estimation of the distribution algorithms is combined with the genetic algorithm to solve the objective function.Finally,the algorithm is numerically simulated by specific cases.Simulation results indicate that the proposed algorithm can perform effective task assignment and trajectory planning for cross-domain unmanned swarms.Furthermore,the solution performance of the hybrid estimation of distribution algorithm(EDA)-genetic algorithm(GA)algorithm is better than that of GA and EDA. 展开更多
关键词 cross-domain swarm unmanned system target assignment trajectory planning joint planning hybrid estimation of distribution algorithm(EDA)-genetic algorithm(GA)
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基于增益调整的Joint-EKF算法估算电池SOC 被引量:3
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作者 吴铁洲 向富超 常春 《电池》 CAS CSCD 北大核心 2018年第3期150-153,共4页
在电流采样过程中,电流漂移噪声会对采样精度造成干扰,进而影响锂离子电池荷电状态(SOC)估算的精度。采用联合扩展卡尔曼滤波(Joint-EKF)算法,以Thevenin模型为等效电路模型基础,将电流漂移值与状态变量同步预测,可提高估算精度。在电... 在电流采样过程中,电流漂移噪声会对采样精度造成干扰,进而影响锂离子电池荷电状态(SOC)估算的精度。采用联合扩展卡尔曼滤波(Joint-EKF)算法,以Thevenin模型为等效电路模型基础,将电流漂移值与状态变量同步预测,可提高估算精度。在电流突变时,需要加快算法修正速度来解决算法跟踪效果差的问题。基于Joint-EKF算法,通过调整滤波增益动态修正SOC,可进一步提高SOC估算精度。结果表明:改进算法后的SOC估算误差为2.8%,比改进前的减小2.4%。 展开更多
关键词 锂离子电池 荷电状态(SOC)估算 联合扩展卡尔曼滤波(joint—EKF) 增益系数
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Faster-than-Nyquist signaling based on filter bank multicarrier modulation with joint optimization
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作者 CHE Hui PENG Dingxiang +1 位作者 GUO Fachang BAI Yong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第6期1208-1223,共16页
Multi-carrier faster-than-Nyquist(MFTN)can improve the spectrum efficiency(SE).In this paper,we first analyze the benefit of time frequency packing MFTN(TFP-MFTN).Then,we propose an efficient digital implementation fo... Multi-carrier faster-than-Nyquist(MFTN)can improve the spectrum efficiency(SE).In this paper,we first analyze the benefit of time frequency packing MFTN(TFP-MFTN).Then,we propose an efficient digital implementation for TFP-MFTN based on filter bank multicarrier modulation.The time frequency packing ratio pair in our proposed implementation scheme is optimized with the SE criterion.Next,the joint optimization for the coded modulation MFTN based on extrinsic information transfer(EXIT)chart is performed.The Monte-Carlo simulations are carried out to verify performance gain of the joint inner and outer code optimization.Simulation results demonstrate that the TFPMFTN has a 0.8 dB and 0.9 dB gain comparing to time packing MFTN(TP-MFTN)and higher order Nyquist at same SE,respectively;the TFP-MFTN with optimized low density parity check(LDPC)code has a 2.9 dB gain comparing to that with digital video broadcasting(DVB)LDPC.Compared with previous work on TFP-MFTN(SE=1.55 bit/s/Hz),the SE of our work is improved by 29%and our work has a 4.1 dB gain at BER=1×10^(-5). 展开更多
关键词 faster-than-Nyquist filter bank multi-carrier time-frequency packing(TFP) spectrum efficiency(SE) joint optimization
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基于特征重构与多时间尺度的锂电池SOH和RUL联合估计 被引量:1
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作者 寇发荣 杨天祥 +2 位作者 罗希 王衎 周东明 《太阳能学报》 北大核心 2025年第6期68-78,共11页
提出一种基于特征重构与多时间尺度的健康状态(SOH)和剩余寿命(RUL)联合估计方法。首先,从锂电池老化数据集中提取健康特征,使用变分模态分解算法重构特征数据;在此基础上,利用贝叶斯算法优化卷积长短期记忆网络构建SOH估计模型,通过微... 提出一种基于特征重构与多时间尺度的健康状态(SOH)和剩余寿命(RUL)联合估计方法。首先,从锂电池老化数据集中提取健康特征,使用变分模态分解算法重构特征数据;在此基础上,利用贝叶斯算法优化卷积长短期记忆网络构建SOH估计模型,通过微观尺度下的算法迭代与宏观尺度下的卷积神经网络模型相结合来实现SOH与RUL准确且高效的估计。利用美国国家航空航天局(NASA)和马里兰大学(CALCE)公开数据集进行验证,结果显示:SOH的估计误差稳定保持在1%以内,估计精度较特征重构前提升约35%;RUL预测结果的平均绝对误差(MAE)和均方根误差(RMSE)分别保持在0.42和0.78以内,实现了SOH和RUL的高精度估计。 展开更多
关键词 锂电池 长短期记忆网络 模态分解 多时间尺度 联合估计 清洁能源
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基于马尔可夫聚类的隐私高维数据发布方法
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作者 刘卓群 龙士工 +1 位作者 张珺铭 刘光源 《计算机工程与设计》 北大核心 2025年第1期117-123,共7页
针对现有差分隐私的方法在处理高维数据发布时面临计算成本高、数据精度低和中心服务器不可信任的问题,提出一种基于马尔可夫聚类的隐私高维数据发布方法MCL-LDP。基于在用户本地实现对用户数据的隐私保护,中心服务器接收到用户本地化... 针对现有差分隐私的方法在处理高维数据发布时面临计算成本高、数据精度低和中心服务器不可信任的问题,提出一种基于马尔可夫聚类的隐私高维数据发布方法MCL-LDP。基于在用户本地实现对用户数据的隐私保护,中心服务器接收到用户本地化差分隐私保护的数据后,构建无向依赖图矩阵表示高维数据的复杂的属性关联性,基于马尔可夫聚类将高维数据属性集分割成多个低维属性簇,利用EM算法计算低维属性簇和重叠属性簇的边缘分布、估计原始数据的联合分布,通过采样合成新的数据集进行发布。实验结果表明,所提出方法在发布高维数据集上有较好的精度、较少的迭代次数和较高的计算效率。 展开更多
关键词 高维数据 本地化差分隐私 马尔可夫聚类 数据发布 联合分布估计 属性关联性 数据合成
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基于最小角回归的稀疏辨识与优化PID控制
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作者 刘艳君 武禹辰 +1 位作者 陈晶 丁锋 《系统工程与电子技术》 北大核心 2025年第8期2706-2714,共9页
针对过程复杂且结构未知的对象,在保证模型有效性的前提下,根据数据信息构建简单模型来简化控制器的求解是亟待解决的问题。以受控自回归模型为例,提出一种基于修正最小角回归算法的稀疏辨识方法。首先将系统模型转化为过参数化的高维... 针对过程复杂且结构未知的对象,在保证模型有效性的前提下,根据数据信息构建简单模型来简化控制器的求解是亟待解决的问题。以受控自回归模型为例,提出一种基于修正最小角回归算法的稀疏辨识方法。首先将系统模型转化为过参数化的高维稀疏模型,然后将最小角回归算法用于稀疏系统辨识,并提出绝对角度停止准则,使算法经过少量的迭代即可获得模型的稀疏参数估计,并同时获得有效的时滞和阶次估计。结合辨识得到的受控自回归模型,引入一种基于指定相位点频率和增益的比例-积分-微分(proportional integral derivative,PID)控制器。数值仿真和平衡机器人的姿态控制仿真表明,该稀疏辨识算法在低数据量下具有较高的辨识精度,建立的模型具有较好的泛化性能,控制器具有良好的控制效果。 展开更多
关键词 最小角回归 稀疏系统辨识 时滞阶次联合估计 停止准则 优化PID控制
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联合弹药毁伤复杂面目标瞄准点高效优化算法 被引量:1
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作者 晏江 尹鹏 +2 位作者 刘彦 张文宇 黄风雷 《兵工学报》 北大核心 2025年第4期150-162,共13页
针对形状不规则复杂面目标多弹瞄准点优化算法计算效率低、稳定性差、优化能力不足的问题,提出一种基于弹药圆概率偏差(Circular Error Probable,CEP)的毁伤概率矩阵库(Damage Probability Matrix Library,DPML)和改进启发式退火优化机... 针对形状不规则复杂面目标多弹瞄准点优化算法计算效率低、稳定性差、优化能力不足的问题,提出一种基于弹药圆概率偏差(Circular Error Probable,CEP)的毁伤概率矩阵库(Damage Probability Matrix Library,DPML)和改进启发式退火优化机制的高效瞄准点优化算法(Efficient Aiming Point Optimization Algorithm,EAPOA)。构建多弹瞄准点优化模型时,除考虑目标形状、导弹毁伤能力外,还考虑导弹直接毁伤、间接毁伤和多弹种联合毁伤等复杂因素对目标毁伤效果的影响。提出一种基于DPML的毁伤概率快速估计算法,提升算法优化效率和鲁棒性;设计一种基于候选瞄准点序列化的优化算法框架,并提出基于全局搜索和改进退火机制的启发式优化算法,降低瞄准点组合求解空间大小并提升算法优化能力。通过6个复杂面目标测试用例验证算法性能。研究结果表明,所提的EAPOA相比于增强精英保留策略遗传算法具有更强的优化能力,且平均优化时间仅为其1/5~1/3,在优化收益和计算效率上具有明显优势。 展开更多
关键词 联合弹药 毁伤评估 瞄准点优化 启发式算法 复杂面目标 毁伤概率
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基于阵列的神经网络水声通信信号多参数联合估计算法
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作者 成乐 刘悦 +2 位作者 胡正良 朱宏娜 罗斌 《通信学报》 北大核心 2025年第1期67-78,共12页
针对水声信道复杂多变且衰减严重等问题,为提升非合作条件下水声通信信号的检测概率并扩大感知范围,设计了一种新型基于阵列多通道时频谱输入的神经网络多参数联合估计算法。该算法通过引入载波频率标签分配策略,将载波频率作为区分不... 针对水声信道复杂多变且衰减严重等问题,为提升非合作条件下水声通信信号的检测概率并扩大感知范围,设计了一种新型基于阵列多通道时频谱输入的神经网络多参数联合估计算法。该算法通过引入载波频率标签分配策略,将载波频率作为区分不同信号的关键物理特征,有效避免了频带外信号和噪声的干扰;利用端到端的多任务学习,能够同时完成信号检测、调制模式识别,以及对信号个数、载波频率、带宽和波达方向的联合估计,从而避免了传统算法中需要先进行波束成形再进行检测识别的复杂流程。仿真实验结果表明,在阵列阵元位置失配和信号被噪声掩蔽的情况下,所提算法仍能实现准确的信号估计。进一步的湖上实验验证了所提算法的实用性和泛化能力。 展开更多
关键词 多参数联合估计 波达方向估计 调制模式识别 阵列信号处理 神经网络
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交叉熵迭代辅助的跳时图案估计与多跳相干合并算法
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作者 苗夏箐 吴睿 +3 位作者 岳平越 张瑞 王帅 潘高峰 《电子与信息学报》 北大核心 2025年第2期480-489,共10页
作为全球化通信网络的重要组成部分,卫星通信因其能够实现全球无缝覆盖和构建天地一体化信息网络而备受关注。跳时(TH)作为一种常用的卫星通信方式,具备强大的抗干扰能力、灵活的频谱利用和高安全性。该文提出一种适用于卫星通信的TH图... 作为全球化通信网络的重要组成部分,卫星通信因其能够实现全球无缝覆盖和构建天地一体化信息网络而备受关注。跳时(TH)作为一种常用的卫星通信方式,具备强大的抗干扰能力、灵活的频谱利用和高安全性。该文提出一种适用于卫星通信的TH图案随机变化系统,以进一步增强数据传输过程的安全性。针对发射功率受限的问题,该文提出多跳信号相干合并策略,并进一步在该策略指导下,面对接收信号信噪比(SNR)低的约束,提出了交叉熵(CE)迭代辅助的跳时图案与多跳载波相位联合估计算法,以合并信噪比损失为目标函数,自适应调整待估参数的概率分布,从而快速收敛至最优解附近。仿真实验证明了该算法在迭代收敛速度、参数估计误差以及合并解调误码率等方面的优异性能。与传统算法相比,所提算法在保持较低复杂度的同时,误码率(BER)性能接近理论最优,有效提高了卫星TH通信系统在复杂环境下的稳定性和可靠性。 展开更多
关键词 跳时通信 多维参数联合估计 跳时图案估计 交叉熵 相干合并
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船舶运动安稳期短期统计特性研究
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作者 张云驰 段文洋 +1 位作者 黄礼敏 马学文 《船舶力学》 北大核心 2025年第7期1023-1033,共11页
舰载机起降、船舶燃油补给、船舶起重作业等海上作业对船舶的运动有着严格的要求,需要在安稳期窗口内进行以确保作业安全。然而,在高海况下安稳期窗口的出现概率较低。因此,提前评估目标海域安稳期的概率对于海上作业的规划和部署至关... 舰载机起降、船舶燃油补给、船舶起重作业等海上作业对船舶的运动有着严格的要求,需要在安稳期窗口内进行以确保作业安全。然而,在高海况下安稳期窗口的出现概率较低。因此,提前评估目标海域安稳期的概率对于海上作业的规划和部署至关重要。针对该问题本文基于船舶运动的统计特性建立了船舶运动概率模型,对安稳期短期统计特性进行研究,并利用仿真数据对运动统计特征与运动幅值–周期联合统计特征进行验证,证明了模型的准确性。随后对安稳期关注的低于作业阈值的连续小幅运动概率进行分析。结果表明,建立的船舶运动概率模型与船舶连续小幅运动概率模型,能够较为准确地反映船舶在相应海况下的运动特征与安稳期出现概率。本研究能够提前在船舶进入某海域作业前给出满足作业要求的安稳期发生概率,同时能在作业前的一段时间内给出安稳期出现的概率,为海上船舶的航行作业计划提供辅助决策。 展开更多
关键词 安稳期 窄带高斯过程 安稳期统计估计 联合分布
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基于视角统一的手姿态估计优化方法
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作者 曹忠锐 谢文军 +3 位作者 王冬 钮立超 王婷玉 刘晓平 《计算机应用研究》 北大核心 2025年第1期293-299,共7页
从深度图像中准确估计手的三维姿态是计算机视觉领域的重要任务。然而,由于手的自遮挡和关节自相似性,使得手姿态估计任务极具挑战性。为了克服这些困难,考察了深度图像采样视角对于估计精度的影响,提出了一种基于视角统一(UVP)的网络... 从深度图像中准确估计手的三维姿态是计算机视觉领域的重要任务。然而,由于手的自遮挡和关节自相似性,使得手姿态估计任务极具挑战性。为了克服这些困难,考察了深度图像采样视角对于估计精度的影响,提出了一种基于视角统一(UVP)的网络。该网络旨在将输入的深度图像重采样为更易于估计的“正面”视角,而后通过原始视角下的特征提高关节估计精度。首先,提出了视角转换模块,实现对输入的单张深度图像的视角旋转,提供作为补充的第二视角;然后,提出了视角统一损失函数,确保转换后的第二视角为“正面”视角,最大程度规避自遮挡问题;最后,通过改变卷积组合结构、降低网络深度等网络轻量化手段,进一步优化方法的性能。通过在三个公开的手姿态数据集(包括ICVL、NYU和MSRA)上进行实验,所提方法分别取得了4.92 mm、7.43 mm和7.02 mm的平均关节位置误差,且在搭载RTX3070的计算机上能以159.39 frame/s的速度运行。可见,转换深度图的采样视角,并融合双视角下的特征有利于提高手部姿态估计的精度。同时,所提方法具备自适应性,并表现出优秀的泛化能力,可以推广到大多数基于单深度图像的手部姿态估计模型,为深度学习在三维手姿态估计中的应用提供了有力支持。 展开更多
关键词 手部姿态估计 手关节自遮挡 视角统一 深度图像 点云变换
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