This paper derives the extended ambiguity function for a bistatic multiple-input multiple-output （MIMO） radar system, which includes the whole radar system parameters： geometric sensor configuration, waveforms, ran...This paper derives the extended ambiguity function for a bistatic multiple-input multiple-output （MIMO） radar system, which includes the whole radar system parameters： geometric sensor configuration, waveforms, range, range rate, target scattering and noise characteristics. Recent research indicates the potential pa- rameter estimate performance of bistatic MIMO radars. And this ambiguity function can be used to analyze the parameter estimate performance for the relationship with the Cramer-Rao bounds of the estimated parameters. Finally, some examples are given to demonstrate the good parameter estimate performance of the bistatic MIMO radar, using the quasi-orthogonal waveforms based on Lorenz chaotic systems.展开更多
Link16 data link is the communication standard of the joint tactical information distribution system(JTIDS)used by the U.S.military and North Atlantic Treaty Organization,which is applied as the opportunistic illumina...Link16 data link is the communication standard of the joint tactical information distribution system(JTIDS)used by the U.S.military and North Atlantic Treaty Organization,which is applied as the opportunistic illuminator for passive radar in this paper.The time-domain expression of the Link16 signal is established,and its ambiguity function expression is derived.The timedelay dimension and Doppler dimension side peaks of which lead to the appearance of the false target during target detection.To solve the problem,the time-delay dimension and Doppler dimension side peaks suppression methods are proposed.For the problem that the conventional mismatched filter(MMF)cannot suppress the time-delay dimension side peaks,a neighborhood MMF(NMMF)is proposed.Experimental results demonstrate the effectiveness of the proposed methods.展开更多
Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit...Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit element increases.A subarray-based space-time coding(sub-STC)radar is explored to alleviate the range resolution reduction.For the proposed radar configuration,an identical waveform is transmitted and it introduces a small time offset in different subarrays.The multidimensional ambiguity function of sub-STC radar is defined by considering resolutions in multiple domains including the range,Doppler,angle and probing direction.Analyses on properties of the multi-dimensional ambiguity function of the sub-STC radar with regard to the spatial coverage,resolution performance and low sidelobes are also given.Results reveal that the range resolution and low sidelobes performance are improved with the proposed approach.展开更多
The primary goal of this work is to characterize the impact of weighting selection strategy and multistatic geometry on the multistatic radar performance. With the relationship between the multistatic ambiguity functi...The primary goal of this work is to characterize the impact of weighting selection strategy and multistatic geometry on the multistatic radar performance. With the relationship between the multistatic ambiguity function （AF） and the multistatie Cram6r-Rao lower bound （CRLB）, the problem of calculating the multistatic AF and the multistatic CRLB as a performance metric for multistatic radar system is studied. Exactly, based on the proper selection of the system parameters, the multistatic radar performance can be significantly improved. The simulation results illustrate that the multistatic AF and the multistatic CRLB can serve as guidelines for future multistatic fusion rule development and multistatic radars deployment.展开更多
Ambiguity function （AF） is proposed to represent ultrasonic signal to resolve the preprocessing problem of different center frequencies and different arriving times among ultrasonic signals for feature extraction, a...Ambiguity function （AF） is proposed to represent ultrasonic signal to resolve the preprocessing problem of different center frequencies and different arriving times among ultrasonic signals for feature extraction, as well as offer time-frequency features for signal classification. Moreover, Karhunen-Loeve （K-L） transform is considered to extract signal features from ambiguity plane, and then the features are presented to probabilistic neural network （PNN） for signal classification. Experimental results show that ambiguity function eliminates the difference of center frequency and arriving time existing in ultrasonic signals, and ambiguity plane features extracted by K-L transform describe the signal of different classes effectively in a reduced dimensional space. Classification result suggests that the ambiguity plane features obtain better performance than the features extracted by wavelet transform （WT）.展开更多
针对间歇采样转发干扰产生的假目标和目标高速运动产生的多普勒频移导致雷达脉压性能急剧下降的问题,提出一种高多普勒容限的线性调频离散相位编码(linear frequency modulation-discrete phase coding,LFM-DPC)复合调制相干波形集设计...针对间歇采样转发干扰产生的假目标和目标高速运动产生的多普勒频移导致雷达脉压性能急剧下降的问题,提出一种高多普勒容限的线性调频离散相位编码(linear frequency modulation-discrete phase coding,LFM-DPC)复合调制相干波形集设计方法。在一定多普勒频移范围内,以最小化未转发信号自模糊函数旁瓣能量以及未转发信号与转发信号互模糊函数能量建立优化模型,并设计一种基于KKT(Karush-Kuhn-Tucker)最优性条件的迭代算法对模型求解。仿真实验表明,相比于遗传算法和单一调制的LFM和DPC信号,基于KKT最优性条件的交替迭代优化算法优化的LFM-DPC波形集有更好的抗间歇采样转发干扰性能。展开更多
目的探讨揿针穴位埋置对腹腔镜下全子宫切除术后患者胃肠功能的影响。方法选取2020年10月—2022年10月该院行腹腔镜下全子宫切除手术的100例患者为研究对象,采用随机数字表法分为试验组及对照组,每组50例。试验组患者在双侧内关及足三...目的探讨揿针穴位埋置对腹腔镜下全子宫切除术后患者胃肠功能的影响。方法选取2020年10月—2022年10月该院行腹腔镜下全子宫切除手术的100例患者为研究对象,采用随机数字表法分为试验组及对照组,每组50例。试验组患者在双侧内关及足三里两个穴位共4个部位埋针,对照组患者进行常规术后护理。观察两组胃肠道功能恢复情况(术后首次排气及排便时间、肠鸣音状况)和不良反应发生情况。结果排除了4例数据记录不全的患者后,最终纳入研究的试验组及对照组患者分别为49例及47例。与对照组比较,试验组胃肠道功能恢复更快,在术后首次排气时间(11.7 h vs 24.2 h,P<0.001),排便时间(48.3 h vs 72.4 h,P<0.001)及肠鸣音恢复时间(6.5 h vs 48.0 h,P<0.001)等各项观察指标上具有显著改善。另一方面,试验组患者术后胃肠道相关并发症的发生率也明显低于对照组。除外术后48 h恶心呕吐发生率的比较差异无统计学意义,在术后6 h、12 h、24 h恶心呕吐症状发生率及术后6 h、12 h、24 h、48 h腹胀症状发生率的对比中,两组数据均具有统计学意义(P<0.05)。结论足三里及内关穴揿针埋置能缩短腹腔镜下全子宫切除术后患者首次排气、排便及肠鸣音恢复时间,同时还能够有效降低患者术后出现恶心、呕吐及腹胀等胃肠道不良反应的发生率。展开更多
基金supported by the Innovation Project for Excellent Postgraduates of Hunan Province (CX2011B018)the Innovation Project for Excellent Postgraduates of National University of Defense Technology (B110402)
文摘This paper derives the extended ambiguity function for a bistatic multiple-input multiple-output （MIMO） radar system, which includes the whole radar system parameters： geometric sensor configuration, waveforms, range, range rate, target scattering and noise characteristics. Recent research indicates the potential pa- rameter estimate performance of bistatic MIMO radars. And this ambiguity function can be used to analyze the parameter estimate performance for the relationship with the Cramer-Rao bounds of the estimated parameters. Finally, some examples are given to demonstrate the good parameter estimate performance of the bistatic MIMO radar, using the quasi-orthogonal waveforms based on Lorenz chaotic systems.
基金the National Natural Science Foundation of China(61401526).
文摘Link16 data link is the communication standard of the joint tactical information distribution system(JTIDS)used by the U.S.military and North Atlantic Treaty Organization,which is applied as the opportunistic illuminator for passive radar in this paper.The time-domain expression of the Link16 signal is established,and its ambiguity function expression is derived.The timedelay dimension and Doppler dimension side peaks of which lead to the appearance of the false target during target detection.To solve the problem,the time-delay dimension and Doppler dimension side peaks suppression methods are proposed.For the problem that the conventional mismatched filter(MMF)cannot suppress the time-delay dimension side peaks,a neighborhood MMF(NMMF)is proposed.Experimental results demonstrate the effectiveness of the proposed methods.
基金supported by the National Key Research and Development Program of China(2016YFE0200400)the Key R&D Program of Shaanxi Province(2017KW-ZD-12)+1 种基金the Postdoctoral Science Foundation of Shaanxi Provincethe Nature Science Foundation of Shaanxi Province
文摘Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit element increases.A subarray-based space-time coding(sub-STC)radar is explored to alleviate the range resolution reduction.For the proposed radar configuration,an identical waveform is transmitted and it introduces a small time offset in different subarrays.The multidimensional ambiguity function of sub-STC radar is defined by considering resolutions in multiple domains including the range,Doppler,angle and probing direction.Analyses on properties of the multi-dimensional ambiguity function of the sub-STC radar with regard to the spatial coverage,resolution performance and low sidelobes are also given.Results reveal that the range resolution and low sidelobes performance are improved with the proposed approach.
基金Project(61271441)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0895)supported by the Program for New Century Excellent Talents in Universities of China
文摘The primary goal of this work is to characterize the impact of weighting selection strategy and multistatic geometry on the multistatic radar performance. With the relationship between the multistatic ambiguity function （AF） and the multistatie Cram6r-Rao lower bound （CRLB）, the problem of calculating the multistatic AF and the multistatic CRLB as a performance metric for multistatic radar system is studied. Exactly, based on the proper selection of the system parameters, the multistatic radar performance can be significantly improved. The simulation results illustrate that the multistatic AF and the multistatic CRLB can serve as guidelines for future multistatic fusion rule development and multistatic radars deployment.
文摘Ambiguity function （AF） is proposed to represent ultrasonic signal to resolve the preprocessing problem of different center frequencies and different arriving times among ultrasonic signals for feature extraction, as well as offer time-frequency features for signal classification. Moreover, Karhunen-Loeve （K-L） transform is considered to extract signal features from ambiguity plane, and then the features are presented to probabilistic neural network （PNN） for signal classification. Experimental results show that ambiguity function eliminates the difference of center frequency and arriving time existing in ultrasonic signals, and ambiguity plane features extracted by K-L transform describe the signal of different classes effectively in a reduced dimensional space. Classification result suggests that the ambiguity plane features obtain better performance than the features extracted by wavelet transform （WT）.
文摘针对间歇采样转发干扰产生的假目标和目标高速运动产生的多普勒频移导致雷达脉压性能急剧下降的问题,提出一种高多普勒容限的线性调频离散相位编码(linear frequency modulation-discrete phase coding,LFM-DPC)复合调制相干波形集设计方法。在一定多普勒频移范围内,以最小化未转发信号自模糊函数旁瓣能量以及未转发信号与转发信号互模糊函数能量建立优化模型,并设计一种基于KKT(Karush-Kuhn-Tucker)最优性条件的迭代算法对模型求解。仿真实验表明,相比于遗传算法和单一调制的LFM和DPC信号,基于KKT最优性条件的交替迭代优化算法优化的LFM-DPC波形集有更好的抗间歇采样转发干扰性能。
文摘目的探讨揿针穴位埋置对腹腔镜下全子宫切除术后患者胃肠功能的影响。方法选取2020年10月—2022年10月该院行腹腔镜下全子宫切除手术的100例患者为研究对象,采用随机数字表法分为试验组及对照组,每组50例。试验组患者在双侧内关及足三里两个穴位共4个部位埋针,对照组患者进行常规术后护理。观察两组胃肠道功能恢复情况(术后首次排气及排便时间、肠鸣音状况)和不良反应发生情况。结果排除了4例数据记录不全的患者后,最终纳入研究的试验组及对照组患者分别为49例及47例。与对照组比较,试验组胃肠道功能恢复更快,在术后首次排气时间(11.7 h vs 24.2 h,P<0.001),排便时间(48.3 h vs 72.4 h,P<0.001)及肠鸣音恢复时间(6.5 h vs 48.0 h,P<0.001)等各项观察指标上具有显著改善。另一方面,试验组患者术后胃肠道相关并发症的发生率也明显低于对照组。除外术后48 h恶心呕吐发生率的比较差异无统计学意义,在术后6 h、12 h、24 h恶心呕吐症状发生率及术后6 h、12 h、24 h、48 h腹胀症状发生率的对比中,两组数据均具有统计学意义(P<0.05)。结论足三里及内关穴揿针埋置能缩短腹腔镜下全子宫切除术后患者首次排气、排便及肠鸣音恢复时间,同时还能够有效降低患者术后出现恶心、呕吐及腹胀等胃肠道不良反应的发生率。
