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Dynamic Rangefinding Device Using Amplitude-Modulated Continuous UltrasonicWave+
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作者 华宏 王涌天 徐彤 《Journal of Beijing Institute of Technology》 EI CAS 1998年第1期55-61,共7页
Aim To develop a high speed and high resolution dynamic rangefinding device for the measurement of large distances.Methods The device was comprised of an ultrasonic transmitter and a receiver,and a receiver , and a co... Aim To develop a high speed and high resolution dynamic rangefinding device for the measurement of large distances.Methods The device was comprised of an ultrasonic transmitter and a receiver,and a receiver , and a continuous ultrasonic wave amplitude-modulated by a low- frequency acoustic signal was used. The rangefinding was achieved by detecting the phase difference between the transmitted and received ultrasonic signals. The design principle. hard- ware implementation , experimental results and performance analysis of the device are included. Results and Conclusion Experiments show that the accuracy of the device are included. within 1.5m while its dynamic data update rate can be up to 40kHz. 展开更多
关键词 position tracker rangefinding continuous ultrasonic wave phase shift
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Optimization and Performance Enhancement of Gesture Recognition Algorithm Based on FMCW Millimeter-Wave Radar
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作者 Zhe He Jinlong Zhou +1 位作者 Decheng Bao Renjing Gao 《Journal of Beijing Institute of Technology》 EI CAS 2024年第5期412-421,共10页
Gesture recognition plays an increasingly important role as the requirements of intelligent systems for human-computer interaction methods increase.To improve the accuracy of the millimeter-wave radar gesture detectio... Gesture recognition plays an increasingly important role as the requirements of intelligent systems for human-computer interaction methods increase.To improve the accuracy of the millimeter-wave radar gesture detection algorithm with limited computational resources,this study improves the detection performance in terms of optimized features and interference filtering.The accuracy of the algorithm is improved by refining the combination of gesture features using a self-constructed dataset,and biometric filtering is introduced to reduce the interference of inanimate object motion.Finally,experiments demonstrate the effectiveness of the proposed algorithm in both mitigating interference from inanimate objects and accurately recognizing gestures.Results show a notable 93.29%average reduction in false detections achieved through the integration of biometric filtering into the algorithm’s interpretation of target movements.Additionally,the algorithm adeptly identifies the six gestures with an average accuracy of 96.84%on embedded systems. 展开更多
关键词 gesture recognition biometric filtering frequency-modulated continuous wave(FMcw)millimeter-wave radar feature optimization human-computer interaction
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Broadband and continuous wave pumped second-harmonic generation from microfiber coated with layered GaSe crystal 被引量:1
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作者 Zhen Hao Biqiang Jiang +3 位作者 Yuxin Ma Ruixuan Yi Xuetao Gan Jianlin Zhao 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2023年第9期59-68,共10页
The conversion-efficiency for second-harmonic(SH)in optical fibers is significantly limited by extremely weak second-order nonlinearity of fused silica,and pulse pump lasers with high peak power are widely employed.He... The conversion-efficiency for second-harmonic(SH)in optical fibers is significantly limited by extremely weak second-order nonlinearity of fused silica,and pulse pump lasers with high peak power are widely employed.Here,we propose a simple strategy to efficiently realize the broadband and continuous wave(CW)pumped SH,by transferring a crystalline GaSe coating onto a microfiber with phase-matching diameter.In the experiment,high efficiency up to 0.08%W-1mm-1 is reached for a C-band pump laser.The high enough efficiency not only guarantees SH at a single frequency pumped by a CW laser,but also multi-frequencies mixing supported by three CW light sources.Moreover,broadband SH spectrum is also achieved under the pump of a superluminescent light-emitting diode source with a 79.3 nm bandwidth.The proposed scheme provides a beneficial method to the enhancement of various nonlinear parameter processes,development of quasi-monochromatic or broadband CW light sources at new wavelength regions. 展开更多
关键词 nonlinear optics second-harmonic generation continuous wave pump high efficiency multi-frequencies mixing broad spectra MICROFIBERS gallium selenide
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基于双注意力机制的FMCW雷达人体行为识别
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作者 卓智海 祝文胜 王双龙 《北京信息科技大学学报(自然科学版)》 2024年第5期58-66,共9页
为了提高调频连续波(frequency modulated continuous wave,FMCW)雷达人体行为识别的分类精度和泛化性能,提出了一种基于双注意力机制的特征融合方法。通过设置阈值,对距离-时间谱图和微多普勒谱图中的有效频谱进行提取、拼接后送入Alex... 为了提高调频连续波(frequency modulated continuous wave,FMCW)雷达人体行为识别的分类精度和泛化性能,提出了一种基于双注意力机制的特征融合方法。通过设置阈值,对距离-时间谱图和微多普勒谱图中的有效频谱进行提取、拼接后送入AlexNet和VGG16神经网络来提取特征;加入空间注意力和改进的通道注意力模块,丢弃冗余信息,以增强对重要信息的关注,获取更感兴趣的特征进行特征融合分类。实验结果表明,该方法对6种日常人体行为的平均识别准确率高达97.0%。 展开更多
关键词 调频连续波雷达 特征融合 通道注意力 空间注意力 人体行为识别
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Stable continuous-wave single-frequency intracavity frequency-doubled laser with intensity noise suppressed in audio frequency region 被引量:1
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作者 Ying-Hao Gao Yuan-Ji Li +1 位作者 Jin-Xia Feng Kuan-Shou Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第9期197-202,共6页
We demonstrated a continuous wave(cw) single-frequency intracavity frequency-doubled Nd:YVO_4/LBO laser with 532 nm output of 7.5 W and 1.06 μm output of 3.1 W, and low intensity noise in audio frequency region.To su... We demonstrated a continuous wave(cw) single-frequency intracavity frequency-doubled Nd:YVO_4/LBO laser with 532 nm output of 7.5 W and 1.06 μm output of 3.1 W, and low intensity noise in audio frequency region.To suppress the intensity noise of the high power 532 nm laser, a laser frequency locking system and a feedback loop based on a Mach-Zehnder interferometer were designed and used.The influences of the frequency stabilization and the crucial parameters of the MZI, such as the power splitting ratio of the beam splitters and the locking state of the MZI, on the intensity noise of the 532 nm laser were investigated in detail.After the experimental optimizations, the laser intensity noise in the frequency region from 0.4 kHz to 10 kHz was significantly suppressed. 展开更多
关键词 continuous wave SINGLE-FREQUENCY INTRACAVITY frequency-doubled LASER noise SUPPRESSION power stabilization audio FREQUENCY
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Modified Omega-K algorithm for processing helicopter-borne frequency modulated continuous waveform rotating synthetic aperture radar data 被引量:2
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作者 Dong Li Guisheng Liao +1 位作者 Yong Liao Lisheng Yang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第3期476-485,共10页
With appropriate geometry configuration, helicopter- borne rotating synthetic aperture radar (ROSAR) can break through the limitations of monostatic synthetic aperture radar (SAR) on forward-looking imaging. With ... With appropriate geometry configuration, helicopter- borne rotating synthetic aperture radar (ROSAR) can break through the limitations of monostatic synthetic aperture radar (SAR) on forward-looking imaging. With this capability, ROSAR has extensive potential applications, such as self-navigation and self-landing. Moreover, it has many advantages if combined with the frequency modulated continuous wave (FMCW) technology. A novel geometric configuration and an imaging algorithm for helicopter-borne FMCW-ROSAR are proposed. Firstly, by per- forming the equivalent phase center principle, the separated trans- mitting and receiving antenna system is equalized to the case of system configuration with antenna for both transmitting and receiving signals. Based on this, the accurate two-dimensional spectrum is obtained and the Doppler frequency shift effect in- duced by the continuous motion of the platform during the long pulse duration is compensated. Next, the impacts of the velocity approximation error on the imaging algorithm are analyzed in de- tail, and the system parameters selection and resolution analysis are presented. The well-focused SAR image is then obtained by using the improved Omega-K algorithm incorporating the accurate compensation method for the velocity approximation error. FJnally, correctness of the analysis and effectiveness of the proposed al- gorithm are demonstrated through simulation results. 展开更多
关键词 helicopter-borne rotating synthetic aperture radar(ROSAR) frequency modulated continuous wave (FMcw) improved Omega-K algorithm two-dimensional spectrum.
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Efficient and high-power laser-diode single-end-pumped Nd:YVO4 continuous wave laser at 1342nm 被引量:1
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作者 张玉萍 郑义 +2 位作者 张会云 王鹏 姚建铨 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第9期2018-2021,共4页
A compact, efficient and high-power laser diode (LD) single-end-pumped Nd:YVO4 laser with continuous-wave emission at 1342 nm is reported. With a single crystal single-end-pumped by fibre-coupled LD array, an outpu... A compact, efficient and high-power laser diode (LD) single-end-pumped Nd:YVO4 laser with continuous-wave emission at 1342 nm is reported. With a single crystal single-end-pumped by fibre-coupled LD array, an output power of 7.36W is obtained from the laser cavity of concave-convex shape, corresponding to an optical-to-optical efficiency of 32.8%. The laser is operated in TEM00 mode with small rms amplitude noise of 0.3%. The influences of the Nd concentration, transmissivity of the output mirror and the cavity length on the output power have been studied experimentally. 展开更多
关键词 laser diode single-end-pumped Nd:YVO4 at 1342 nm continuous wave efficiency
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Micro-failure process and failure mechanism of brittle rock under uniaxial compression using continuous real-time wave velocity measurement 被引量:3
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作者 WU Zhi-jun WANG Zhi-yang +2 位作者 FAN Li-feng WENG Lei LIU Quan-sheng 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第2期556-571,共16页
In this study,the micro-failure process and failure mechanism of a typical brittle rock under uniaxial compression are investigated via continuous real-time measurement of wave velocities.The experimental results indi... In this study,the micro-failure process and failure mechanism of a typical brittle rock under uniaxial compression are investigated via continuous real-time measurement of wave velocities.The experimental results indicate that the evolutions of wave velocities became progressively anisotropic under uniaxial loading due to the direction-dependent development of micro-damage.A wave velocity model considering the inner anisotropic crack evolution is proposed to accurately describe the variations of wave velocities during uniaxial compression testing.Based on which,the effective elastic parameters are inferred by a transverse isotropic constitutive model,and the evolutions of the crack density are inversed using a self-consistent damage model.It is found that the propagation of axial cracks dominates the failure process of brittle rock under uniaxial loading and oblique shear cracks develop with the appearance of macrocrack. 展开更多
关键词 elastic wave velocity brittle rock failure uniaxial compression test continuous real-time measurement anisotropic damage evolution theory and modelling
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Cell-type continuous electromagnetic radiation system generating millimeter waves for active denial system applications 被引量:1
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作者 Sun-Hong Min Ohjoon Kwon +17 位作者 Matlabjon Sattorov Seontae Kim In-Keun Baek Seunghyuk Park Ranjan Kumar Barik Anirban Bera Dongpyo Hong Seonmyeong Kim Bong Hwan Hong Chawon Park Sukhwal Ma Minho Kim Kyo Chul Lee Yong Jin Lee Han Byul Kwon Young Joon Yoo Sang Yoon Park Gun-Sik Park 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第10期1895-1913,共19页
The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living orga... The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living organisms.It irradiates a biological sample placed in a 30×30×50 cm^(3)cell with electromagnetic waves in the 3.15-mm-wavelength region(with an output of≥1 W)and analyzes the temperature change of the sample.A vacuum electronic device-based coupled-cavity backward-wave oscillator converts the electron energy of the electron beam into radiofrequency(RF)energy and radiates it to the target through an antenna,increasing the temperature through the absorption of RF energy in the skin.The system causes pain and ultimately reduces combat power.A cell-type continuous electromagnetic radiation system consisting of four parts—an electromagnetic-wave generator,a highvoltage power supply,a test cell,and a system controller—generates an RF signal of≥1 W in a continuous waveform at a 95-GHz center frequency,as well as a chemical solution with a dielectric constant similar to that of the skin of a living organism.An increase of 5°C lasting approximately 10 s was confirmed through an experiment. 展开更多
关键词 Millimeter waves Terahertz waves Coupled-cavity backward wave oscillator(CCBWO) Cell-type continuous electromagnetic radiation Active denial system(ADS) Directed-energy weapon(DEW)
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多波段FMCW雷达低慢小探测数据集(LSS-FMCWR-1.0)及高分辨微动特征提取方法 被引量:3
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作者 陈小龙 袁旺 +4 位作者 杜晓林 于刚 何肖阳 关键 汪兴海 《雷达学报(中英文)》 EI CSCD 北大核心 2024年第3期539-553,共15页
无人机等低慢小目标探测对雷达目标检测和识别技术提出了很高的挑战,迫切需要构建相关数据集,支撑低慢小探测技术的发展和应用。该文公开了一个多波段调频连续波(FMCW)雷达低慢小目标探测数据集,基于Ku波段和L波段的FMCW雷达采集6种类... 无人机等低慢小目标探测对雷达目标检测和识别技术提出了很高的挑战,迫切需要构建相关数据集,支撑低慢小探测技术的发展和应用。该文公开了一个多波段调频连续波(FMCW)雷达低慢小目标探测数据集,基于Ku波段和L波段的FMCW雷达采集6种类型的无人机回波数据,通过雷达调制周期和调制带宽,具备不同时域和频域分辨和测量能力,构建了多波段FMCW雷达低慢小探测数据集(LSS-FMCWR-1.0)。为了进一步提升无人机微动特征提取能力,该文提出基于局部极大值同步提取变换的无人机微动提取和参数估计方法,在短时傅里叶变换的基础上提取时频能量最大值,保留有用信号分量,实现精细化时频表示。基于LSS-FMCWR-1.0进行验证分析,结果表明该方法相较于传统时频方法,熵值平均降低了5.3 dB,旋翼叶长估计误差降低了27.7%,所提方法兼顾高时频分辨率和较高的参数估计精度,为后续目标识别奠定了基础。 展开更多
关键词 低慢小目标 调频连续波雷达 微动特性 局部极大值同步提取变换 公开数据集
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Experimental Research on the Propagation Process of Continuous Rotating Detonation Wave 被引量:16
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作者 Quan ZHENG Chun-sheng WENG Qiao-dong BAI 《Defence Technology(防务技术)》 SCIE EI CAS 2013年第4期201-207,共7页
In order to study the propagation mechanism of continuous rotating detonation wave,the H2/air continuous rotating detonation engine ignited by tangentially installed H2/O2pre-detonation tube is studied experimentally ... In order to study the propagation mechanism of continuous rotating detonation wave,the H2/air continuous rotating detonation engine ignited by tangentially installed H2/O2pre-detonation tube is studied experimentally using a tilt slot injector structure.The experimental results show that the stable rotating detonation wave can be gained successfully with the equivalent ratio of 0.93.The propagation frequency and velocity of rotating detonation wave range from 5200 to 5500 Hz and from 1518.5 to 1606.1 m/s,respectively.Three propagation modes,such as rotation,reversal and bifurcation,of detonation wave are verified through the analysis of propagation mechanism of rotating detonation wave. 展开更多
关键词 连续旋转 传播过程 爆轰波 实验 传播机制 传播模式 传播机理 喷射器
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基于延迟断点映射FMCW的双功能雷达通信系统设计 被引量:2
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作者 徐瑞 文瑞铭 +2 位作者 黄子涵 李钢 文光俊 《电子科技大学学报》 EI CAS CSCD 北大核心 2024年第2期210-218,共9页
基于调频连续波(Frequency Modulated Continuous Wave, FMCW)的双功能雷达通信(Dual-Functional RadarCommunication, DFRC)系统具有时频利用率高、抗多普勒性能强、距离旁瓣低的特点。现有的FMCW-DFRC波形系统产生双功能性能恶化,并... 基于调频连续波(Frequency Modulated Continuous Wave, FMCW)的双功能雷达通信(Dual-Functional RadarCommunication, DFRC)系统具有时频利用率高、抗多普勒性能强、距离旁瓣低的特点。现有的FMCW-DFRC波形系统产生双功能性能恶化,并增加通信接收机的链路复杂度。设计了一种基于延迟断点映射(Delayed Breakpoint Mapping, DBM)FMCW的DFRC系统,通过啁啾周期内延迟断点位置的映射和被分割的簇间的相位进行数据调制。通信接收端在载波混频和欠采样后,在数字域实现去啁啾、码片对齐和数据解调,极大降低了接收端生成相干信号和ADC性能的需求。在雷达处理链路中,设计了断点区域删除与拼接(Breakpoint Area Deletion and Splicing, BADS)方案,使DFRC的雷达性能与无调制的FMCW一致。仿真结果表明,与无补偿的方案相比,BADS方案距离图像的副瓣幅度减小约37 dB,且不受调制数据的影响。与现有基于啁啾波形的DFRC方案的通信性能相比,DBM-FMCW降低了约3 dB误符号率。 展开更多
关键词 啁啾信号 双功能雷达通信 调频连续波 旁瓣抑制 欠采样
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片上集成FMCW激光雷达研究进展(封面文章·特邀)
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作者 朱精果 袁野 +2 位作者 姜成昊 刘宇 赵政伟 《红外与激光工程》 EI CSCD 北大核心 2024年第8期1-17,共17页
随着硅基光电子集成技术快速发展,具有测距测速一体、探测精度高、抗干扰能力强的片上集成调频连续波(Frequency Modulated Continuous Wave,FMCW)激光雷达已成为研究热点,并在智能驾驶、航空航天、目标监测和公共安全等领域释放出越来... 随着硅基光电子集成技术快速发展,具有测距测速一体、探测精度高、抗干扰能力强的片上集成调频连续波(Frequency Modulated Continuous Wave,FMCW)激光雷达已成为研究热点,并在智能驾驶、航空航天、目标监测和公共安全等领域释放出越来越大的应用潜力。文中聚焦基于光学相控阵(Optical Phased Array,OPA)的片上集成FMCW激光雷达,介绍了系统工作原理及典型组成,针对国内外研究进展,概述分析了片上集成FMCW激光雷达的发展现状,同时从调频、发射、扫描、探测和处理等角度凝练了主要关键技术,并梳理了片上集成FMCW激光雷达在相关领域的应用前景和典型系统示例。最后,分析并展望了片上集成FMCW激光雷达面临的潜在挑战及发展趋势。 展开更多
关键词 激光雷达 调频连续波 光学相控阵 片上集成
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Cylindrical Guided Wave Signals for Underground Pipe Inspection using Different Continuous Wavelet Mother Functions 被引量:1
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作者 Rais Ahmad Tribikram Kundu 《Journal of Civil Engineering and Architecture》 2011年第12期1103-1110,共8页
Over the past decade, wavelets provided a powerful and flexible set of tools for handling fundamental problems in science and engineering. Wavelet analyses are being used for solving problems in different engineering ... Over the past decade, wavelets provided a powerful and flexible set of tools for handling fundamental problems in science and engineering. Wavelet analyses are being used for solving problems in different engineering areas like audio de-noising, signal compression, object detection, image decomposition, speech recognition etc. Wavelet analysis employs orthonormal as well as non-orthonornal functions. This research investigates the effectiveness of wavelet analysis in detecting defects in underground steel pipe networks. Continuous Wavelet Transforms (CWT) has been performed on the received signals of cylindrical guided waves. Cylindrical Guided waves are generated and propagated through the pipe wall boundaries in a pitch-catch system. Piezo-electric transducers are used to generate as well as receive guided waves. Several mother wavelet functions such as Daubechies, Symlet, Coiflet and Meyer have been used for the Continuous Wavelet Transform to investigate the most suitable function for defect detection. This research also investigates the effect of surrounding soil on wavelet transforms for different mother wavelet functions. 展开更多
关键词 wavelet analysis guided waves mother wavelet functions continuous wavelet transform.
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Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate 被引量:7
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作者 丁欣 张少敏 +3 位作者 马洪梅 庞明 姚建铨 李卓 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第1期211-216,共6页
This paper reports a continuous-wave (CW) mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. C... This paper reports a continuous-wave (CW) mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN's grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%. 展开更多
关键词 continuous-wave MID-INFRARED intracavity optical parametric oscillator periodically poled lithium niobate crystal
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基于多核DSP的星载双基FMCW SAR成像算法实现
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作者 陈洋 肖国尧 +3 位作者 全英汇 任爱锋 别博文 邢孟道 《系统工程与电子技术》 EI CSCD 北大核心 2024年第1期121-129,共9页
调频连续波(frequency modulated continuous wave,FMCW)合成孔径雷达(synthetic aperture radar,SAR)降低了传感器的峰值传输功率,使系统的重量和成本最小化,被广泛应用于机载平台。将双基地构型与FMCW技术相结合,应用于星载平台,即构... 调频连续波(frequency modulated continuous wave,FMCW)合成孔径雷达(synthetic aperture radar,SAR)降低了传感器的峰值传输功率,使系统的重量和成本最小化,被广泛应用于机载平台。将双基地构型与FMCW技术相结合,应用于星载平台,即构成星载双基地FMCW SAR。本文对距离多普勒(range-Doppler,RD)算法进行改进,建立起一种高性能的适宜星载双基地平台的FMCW SAR成像频域算法,这种算法的处理精度明显提高,成像效果更好。基于多核数字信号处理器(digital signal processor,DSP)构建适用于星载双基SAR成像算法的并行处理架构,完成软硬件设计实现。验证了所提软件架构可以满足实时成像需求,以及算法工程化实现的可行性。 展开更多
关键词 调频连续波合成孔径雷达成像算法 星载双基 多核数字信号处理器 实时处理
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Electroacupuncture with different waveforms for primary dysmenorrhea:A randomized controlled trial
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作者 Xiaona Wu Jingxue Yuan +5 位作者 Jinxia Ni Xiuli Ma Ziniu Zhang Yini Hua Juwei Dong Bob Peng Wang 《Journal of Traditional Chinese Medical Sciences》 CAS 2024年第3期357-362,共6页
Objective:To observe and compare the clinical effects of different electroacupuncture waveforms on primary dysmenorrhea.Methods: This was a prospective,randomized,three-group,parallel-controlled trial.Participants wit... Objective:To observe and compare the clinical effects of different electroacupuncture waveforms on primary dysmenorrhea.Methods: This was a prospective,randomized,three-group,parallel-controlled trial.Participants with primary dysmenorrhea were randomly divided into dense-sparse wave,continuous wave,and discontinuous wave groups in a 1:1:1 ratio.Two lateral Ciliao(BL 32)points were used.All three groups started treatment 3–5 days before menstruation,once a day for six sessions per course of treatment,one course of treatment per menstrual cycle,and three menstrual cycles.The primary outcome measure was the proportion with an average visual analog scale(VAS)score reduction of≥50%from baseline for dysmenorrhea in the third menstrual cycle during treatment.The secondary outcome measures included changes in dysmenorrhea VAS scores,Cox Menstrual Symptom Scale scores and the proportion of patients taking analgesic drugs.Results: The proportion of cases where the average VAS score for dysmenorrhea decreased by≥50%from baseline in the third menstrual cycle was not statistically significant(P>.05).Precisely 30 min after acupuncture and regarding immediate analgesia on the most severe day of dysmenorrhea,there was a statistically significant difference in the dense-sparse wave group compared with the other two groups during the third menstrual cycle(P<.05).Additionally,there was a statistically significant difference between the dense-sparse wave and discontinuous wave groups 24 h after acupuncture(P<.05).Conclusions: Waveform electroacupuncture can alleviate primary dysmenorrhea and its related symptoms in patients.The three groups showed similar results in terms of short-and long-term analgesic efficacy and a reduction in the number of patients taking analgesic drugs.Regarding achieving immediate analgesia,the dense-sparse wave group was slightly better than the other two groups. 展开更多
关键词 waveFORMS Ciliao(BL 32) ELECTROACUPUNCTURE Primary dysmenorrhea Randomized controlled trial Dense-sparse waves continuous waves Discontinuous waves
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High efficiency continuous-wave tunable signal output of an intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate 被引量:5
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作者 丁欣 盛泉 +6 位作者 陈娜 禹宣伊 王睿 张衡 温午麒 王鹏 姚建铨 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第10期4314-4318,共5页
In this paper we report on a continuous-wave (CW) intracavity singly resonant optical parametric oscillator (ICSRO) based on periodically poled LiNbO3 (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. Consi... In this paper we report on a continuous-wave (CW) intracavity singly resonant optical parametric oscillator (ICSRO) based on periodically poled LiNbO3 (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%. 展开更多
关键词 continuous-wave intracavity optical parametric oscillator periodically poled lithium niobate crystal tunable eye-safe laser
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强干扰下基于三阶互累积量的FMCW雷达信号DOA估计算法 被引量:1
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作者 夏楠 马昕昕 王思琦 《电子学报》 EI CAS CSCD 北大核心 2024年第2期510-517,共8页
针对车载调频连续波雷达存在相互干扰的实际情况,本文提出了一种基于三阶互累积量的多目标波达方向超分辨估计方法.该方法利用同步采集的阵列信号并根据回波信号和干扰信号的非相关特性,构造三阶互累积量矩阵,随后根据子空间方法获得二... 针对车载调频连续波雷达存在相互干扰的实际情况,本文提出了一种基于三阶互累积量的多目标波达方向超分辨估计方法.该方法利用同步采集的阵列信号并根据回波信号和干扰信号的非相关特性,构造三阶互累积量矩阵,随后根据子空间方法获得二维空间谱,实现距离和方位的联合估计.计算机仿真结果表明,本文所提方法能够在抑制强干扰影响的同时实现3°以内多目标识别,与现有超分辨法和重构法相比,具有更高的角度分辨率和估计精度. 展开更多
关键词 调频连续波雷达 波达方向估计 空间谱 三阶互累积量 干扰抑制
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Tunable, continuous-wave single-resonant optical parametric oscillator with output coupling for resonant wave
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作者 郑雄桦 张宝夫 +1 位作者 焦中兴 王彪 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第1期620-623,共4页
We present a continuous-wave singly-resonant optical parametric oscillator with 1.5% output coupling of the reso- nant signal wave, based on an angle-polished MgO-doped periodically poled lithium niobate (MgO:PPLN)... We present a continuous-wave singly-resonant optical parametric oscillator with 1.5% output coupling of the reso- nant signal wave, based on an angle-polished MgO-doped periodically poled lithium niobate (MgO:PPLN), pumped by a commercial Nd:YVO4 laser at 1064 nm. The output-coupled optical parametric oscillator delivers a maximum total output power of 4.19 W with 42.8% extraction efficiency, across a tuning range of 1717 nm in the near- and mid-infrared region. This indicates improvements of 1.87 W in output power, 19.1% in extraction efficiency and 213 nm in tuning range exten- sion in comparison with the optical parametric oscillator with no output coupling, while at the expense of increasing the oscillation threshold by a factor of - 2. Moreover, it is confirmed that the finite output coupling also contributes to the reduction of the thermal effects in crystal. 展开更多
关键词 continuous wave frequency conversion optical parametric oscillators output coupling
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