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UAV Velocity Measurement for Ground Moving Target 被引量:2
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作者 黄大庆 徐诚 +1 位作者 韩伟 王东振 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2015年第1期9-15,共7页
To satisfy the demand of measuring the velocity of ground moving target through unmanned aerial vehicle(UAV)electro-optical platform,two velocity measurement methods are proposed.Firstly,a velocity measurement method ... To satisfy the demand of measuring the velocity of ground moving target through unmanned aerial vehicle(UAV)electro-optical platform,two velocity measurement methods are proposed.Firstly,a velocity measurement method based on target localization is derived,using the position difference between two points with the advantages of easy deployment and realization.Then a mathematical model for measuring target velocity is built and described by 15 variables,i.e.UAV velocity,UAV attitude angular rate,camera direction angular rate and so on.Moreover,the causes of velocity measurement error are analyzed and a formula is derived for calculating the measurement error.Finally,the simulation results show that angular rate error has a strong influence on the velocity measurement accuracy,especially the UAV pitch angular rate error,roll angular rate error and the camera angular altitude rate error,thus indicating the direction for improving velocity measurement precision. 展开更多
关键词 unmanned aerial vehicle(UAV) target velocity measurement target localization velocity measurement error
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Velocity Measurement and Freezing Technology of Multi-shot Pellet on HL-1M Tokamak 被引量:1
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作者 李波 李立 +6 位作者 肖正贵 王明旭 刘德权 郑银甲 冯震 王明建 徐小桥 《Plasma Science and Technology》 SCIE EI CAS CSCD 2001年第5期971-976,共6页
A measuring system for high-speed hydrogen ice pellet was introduced in this paper and the photographing of flying pellet taken therein. With the system, a pellet (minimum size of φ 0.3 mm) velocity (ranging from 50 ... A measuring system for high-speed hydrogen ice pellet was introduced in this paper and the photographing of flying pellet taken therein. With the system, a pellet (minimum size of φ 0.3 mm) velocity (ranging from 50 m/s to 2500 m/s) can be measured in the HL-1M tokamak fueling experiments. By analyzing photographs and the conditions of frozen pellets (including gas supply, gas replenishment, temperature controlling etc), the pellet-freezing technology is summarized in the paper. 展开更多
关键词 velocity measurement and Freezing Technology of Multi-shot Pellet on HL-1M Tokamak HL
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Asymptotic bounded consensus tracking of double-integrator multi-agent systems with bounded-jerk target based on sampled-data without velocity measurements
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作者 Shuang-Shuang Wu Zhi-Hai Wu +1 位作者 Li Peng Lin-Bo Xie 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第1期591-596,共6页
This paper investigates asymptotic bounded consensus tracking(ABCT) of double-integrator multi-agent systems(MASs) with an asymptotically-unbounded-acceleration and bounded-jerk target(AUABJT) available to parti... This paper investigates asymptotic bounded consensus tracking(ABCT) of double-integrator multi-agent systems(MASs) with an asymptotically-unbounded-acceleration and bounded-jerk target(AUABJT) available to partial agents based on sampled-data without velocity measurements. A sampled-data consensus tracking protocol(CTP) without velocity measurements is proposed to guarantee that double-integrator MASs track an AUABJT available to only partial agents.The eigenvalue analysis method together with the augmented matrix method is used to obtain the necessary and sufficient conditions for ABCT. A numerical example is provided to illustrate the effectiveness of theoretical results. 展开更多
关键词 asymptotic bounded consensus tracking multi-agent systems without velocity measurements sampled-data control
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Velocity measurement technique for high-speed targets based on digital fine spectral line tracking
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作者 Wen Shuliang Yuan Qi 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2006年第1期6-12,共7页
Target vdocity and acceleration are two of the most important features for identification of warheads and decoys in ballistic missile defense phased array radar systems. Velocity compensation is also the necessary ste... Target vdocity and acceleration are two of the most important features for identification of warheads and decoys in ballistic missile defense phased array radar systems. Velocity compensation is also the necessary step for one-dimensional range profile imaging. According to the high-vdocity characteristics of ballistic objects and the low data rate of phased array radars with multiple target tracking, a fine spectral line digital velocity tracking frame is presented and a new method is developed to extract velocity error and resolve the velocity ambiguity in the measurement loop. Simulation results demonstrate the effectiveness of the proposed technique. 展开更多
关键词 radar tracking radial velocity measurement velocity error extraction velocity ambiguity
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High-Precision Wideband Phase-Derived Velocity Measurement for Micro-Motion Extraction
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作者 Yuan Jiang Huayu Fan +1 位作者 Quanhua Liu Xinliang Chen 《Journal of Beijing Institute of Technology》 EI CAS 2017年第1期106-114,共9页
A phase-derived velocity measurement method is proposed in a wideband coherent system,based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets.The Cramer-Rao low band of v... A phase-derived velocity measurement method is proposed in a wideband coherent system,based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets.The Cramer-Rao low band of velocity measurement precision is deduced,demonstrating the high precision of the proposed method.Simulations and out-field experiments further validate the effectiveness of the proposed method in high-precision measurement and micro-motion extraction for targets with weak reflection intensity.Compared with the long-time integration approaches for velocity measurement,the phase-derived method is easy to implement and meets the requirement for high data rate,which makes it suitable for micro-motion feature extraction in wideband systems. 展开更多
关键词 phase-derived velocity measurement micro-motion extraction wideband coherent sys-tem high-precision measurement
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A Novel Approach for Warhead Fragments Velocity Measurement Based on Laser Screen
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作者 刘吉 赵冬娥 周汉昌 《Journal of Measurement Science and Instrumentation》 CAS 2011年第3期303-306,共4页
The velocity of warhead fragment is key criteria to determine its mutilation efficiency.We have designed an optoelectronic system to accurately measure the average velocity of warhead fragments.The apparatus including... The velocity of warhead fragment is key criteria to determine its mutilation efficiency.We have designed an optoelectronic system to accurately measure the average velocity of warhead fragments.The apparatus including two parallel laser screens spaced apart at a known fixed distance for providing time measurement start and stop signals.The large effective screen area is formed by laser source,retro-reflector and large area photo-diode with a central hole.Whenever a moving fragment interrupts two optical screen,the corresponding photometers senses the event,due to partial obscuration of the incident energy.Experiments have been performed to measure velocity of the different kinds of projectiles and fragments within various size and velocity ranges,including 7.62 mm bullet shooting experiments,prefabricated steel-ball exploding experiments.They were proved that the system is adequate to measure the velocity of larger than 5 mm,less than 1 000 m/s in the range,when fixed trajectory,test the velocity of the projectile average relative deviation is less than 4.21%.The system can perform satisfactorily with a lot of advantages such as larger effective light screen area,quick response speed,low uncertainty,strong repetition and reliability,etc. 展开更多
关键词 non-contact measurement velocity measurement laser screen retro-reflector
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Fixed-Time Anti-Disturbance Average-Tracking for Multi-Agent Systems Without Velocity Measurements
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作者 LI Yuling LIU Chenglin +1 位作者 ZHANG Ya CHEN Yangyang 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2024年第3期985-1002,共18页
In this paper,the authors tackle a fixed-time average-tracking problem for multi-agent systems which do not require velocity measurements and are affected by external mismatched and matched disturbances.The objective ... In this paper,the authors tackle a fixed-time average-tracking problem for multi-agent systems which do not require velocity measurements and are affected by external mismatched and matched disturbances.The objective requires the considered agents with second-order dynamics to follow the average value of several time-varying reference signals,each of which is acquired by only one agent.First of all,the average value is estimated by using a novel distributed average estimator in a fixed time.Second,an original observer is created to provide estimated values in a fixed time for external mismatched and matched disturbances as well as unmeasured velocities of agents.Then,the authors propose a novel fixed-time anti-disturbance average-tracking protocol with the aid of the observer and a sliding mode surface.In the end,the feasibility of theoretical analysis is illustrated by some simulation experiments. 展开更多
关键词 Average-tracking control fixed-time algorithm fixed-time observer mismatched distur-bances multi-agent systems velocity measurements
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Velocity measurement based on orthogonal CCD shadow photograph system in Ballistic range 被引量:7
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作者 LUO Hong-e,GU Jin-liang,CHEN Ping,XIA Yan,GUO Jian-guo,LI Bao-ming National Key Laboratory of Science and Technology on Ballistics,Nanjing University of Science and Technology,Nanjing 210094,China 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2010年第1期127-130,共4页
A method of measuring the velocity of fast moving object by charge coupled device (CCD) shadow photograph system is developed. This system consists of high resolution orthogonal CCD cameras, time detecting device an... A method of measuring the velocity of fast moving object by charge coupled device (CCD) shadow photograph system is developed. This system consists of high resolution orthogonal CCD cameras, time detecting device and the pulsed laser which can generate two short laser pulses with adjustable interval more than 100 μs. Experiments are conducted to measure the velocity of the flying steel ball. The results show that the proposed velocity measurement is effective in modem ballistic measurement. 展开更多
关键词 orthogonal CCD shadow photograph system twice sparking laser source velocity measurement
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Development of an all-fiber heterodyne lidar for range and velocity measurements 被引量:4
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作者 杨馥 贺岩 +1 位作者 尚建华 陈卫标 《Chinese Optics Letters》 SCIE EI CAS CSCD 2010年第7期713-716,共4页
A 1550-nm all-fiber monostatic lidar system based on linear chirp amplitude modulation and heterodyne detection for the measurements of range and velocity is presented. The signal processing method is given, after whi... A 1550-nm all-fiber monostatic lidar system based on linear chirp amplitude modulation and heterodyne detection for the measurements of range and velocity is presented. The signal processing method is given, after which the relationship between the peak frequency values in the final signal spectrum, the target's range, and the line-of-sight velocity is obtained in the presence of the fiber end-face-reflected signal plaguing many monostatic lidar systems. The range of an electric fan as well as the line-of-sight fan speed of different levels is tested. This proposed system has a potential application for the space-borne landing system. 展开更多
关键词 Chirp modulation HETERODYNING Optical radar velocity measurement
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Fundamental research on the size and velocity measurements of coal powder by trajectory imaging 被引量:1
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作者 Xue-cheng WU Ying-chun WU +6 位作者 Cong-chang ZHANG Guo-neng LI Qun-xing HUANG Ling-hong CHEN Kun-zan QIU Hao ZHOU Ke-fa CEN 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2013年第5期377-382,共6页
A trajectory imaging based method for measuring the velocity and diameter of coal particles was presented.By using an industrial charge-coupled device(CCD)camera and a low power semiconductor laser,the images of coal ... A trajectory imaging based method for measuring the velocity and diameter of coal particles was presented.By using an industrial charge-coupled device(CCD)camera and a low power semiconductor laser,the images of coal particles under relatively long exposure time were recorded and then processed to yield both the velocities and sizes.Fundamental research on this method with special attention to recording parameters,e.g.,magnification factor and exposure time,was carried out.For most of the test cases,the results agree with those obtained by particle image velocimetry(PIV)and shadow imaging method.Measurements with good accuracy can be obtained when the imaging magnification factor and exposure time are set appropriately,making N be larger than 3.5,and R between 5-7,where N and R are the number of pixels occupied by the average width and the ratio of length to width of particle trajectory on the image,respectively.The work indicates the feasibility and potential application of the present measurement method for online measurement of coal powder in pipes in industrial power plants. 展开更多
关键词 Trajectory imaging velocity measurement Size measurement Coal powder
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High sampling-rate measurement of turbulence velocity fluctuations in Mach 1.8 Laval jet using interferometric Rayleigh scattering 被引量:4
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作者 Li Chen Fu-Rong Yang +4 位作者 Tie Su Wei-Yi Bao Bo Yan Shuang Chen Ren-Bing Li 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第2期341-344,共4页
Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement a... Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement accuracy is then evaluated by comparing with hot wire anemometry results. Moreover, the distributions of velocity and turbulence intensity in a supersonic free jet from a Laval nozzle with a Mach number of 1.8 are also obtained quantitatively. The sampling rate in this measurement is determined to be approximately 10 k Hz. 展开更多
关键词 Fabry–Pérot interferometer Rayleigh scattering time-resolved velocity measurement turbulence
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Reliability analysis of in-situ stress measurement using circumferential velocity anisotropy
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作者 Jiandong Liu1, 2, Luhe Shen1, 2, Juan Jin1, 2 1 Key Laboratory of Oil and Gas Reservoirs, China National Petroleum Corporation, Beijing, 100083, China 2 PetroChina Research Institute of Petroleum Exploration and Development, Beijing, 100083, China 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2011年第S1期457-460,共4页
In-situ stress measurement for deep reservoir formation is difficult in terms of security, reliability and technique. Acoustic velocity anisotropy test is a basic method for stress measurement of rock cores, which is ... In-situ stress measurement for deep reservoir formation is difficult in terms of security, reliability and technique. Acoustic velocity anisotropy test is a basic method for stress measurement of rock cores, which is based on the distribution of acoustic velocity in different directions around rock cores. The heterogeneity of core samples, such as fractures and gravel contained, can also lead to wave velocity anisotropy. Therefore, the corresponding reliability evaluation method is established to exclude some other anisotropy factors caused by non-tectonic stresses. In this paper, the reliability of testing results is evaluated from three aspects, i.e. phase difference, anisotropy index and waveform, to remove the factors caused by non-tectonic stresses. 展开更多
关键词 acoustic velocity measurement wave velocity anisotropy in-situ stress measurement
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Research on sound velocity measurement in a laboratory for large elastic materials
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作者 ZHU Hanhao PIAO Shengchun +2 位作者 ZHANG Haigang LIU Wei AN Xudong 《Chinese Journal of Acoustics》 2014年第2期121-135,共15页
A measurement scheme carried out in a tank is designed to obtain the compressionaland shear-wave velocities of a large elastic material.A hydrophone is used to receive the high frequency acoustic signals which penetra... A measurement scheme carried out in a tank is designed to obtain the compressionaland shear-wave velocities of a large elastic material.A hydrophone is used to receive the high frequency acoustic signals which penetrate the tested material,in order to determine the transmission time from the source to the hydrophone,the transmission time is also calculated according to the ray acoustic theory in layered media.A cost function is built based on the measured and the calculated transmission time,then the compressional- and shear-wave velocities can be obtained using the optimization algorithm.Compared with the traditional measurement scheme,this approach can not only get the 2 kinds of sound velocities in the tested material at the same time,but also keep the integrality of the tested material.With the proposed measurement system,the uncertainty of measurement results is less than 3.5%. 展开更多
关键词 Research on sound velocity measurement in a laboratory for large elastic materials
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Measurement of the Plasma Rotation Velocity by Using Visible Spectrum on HL-1M Mokamak 被引量:1
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作者 罗俊林 李伟 +3 位作者 王恩耀 董贾福 唐年益 刘泽田 《Plasma Science and Technology》 SCIE EI CAS CSCD 2001年第2期683-690,共8页
The plasma rotation velocity were measured in HL-1M with Doppler shifts of CⅢ、 C Ⅱ、 O Ⅱ and H. line by a SKD high resolution spectrometer. The effects .of density' hydrogen pellet injection and carbon impuri... The plasma rotation velocity were measured in HL-1M with Doppler shifts of CⅢ、 C Ⅱ、 O Ⅱ and H. line by a SKD high resolution spectrometer. The effects .of density' hydrogen pellet injection and carbon impurities injected by laser-blow-off on toroidal(V) and poloidal (Vθ)rotation velocity have been observed. The Vθ measured from H. line is only half of that from C Ⅱ impurity line. 展开更多
关键词 measurement of the Plasma Rotation velocity by Using Visible Spectrum on HL-1M Mokamak HL
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Using a linear array to estimate the velocity of underwater moving targets 被引量:2
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作者 严光洪 陈志菲 孙进才 《Journal of Marine Science and Application》 2009年第4期343-347,共5页
A new method uses a linear array that takes advantage of underwater physical sound fields to estimate the velocity of an underwater moving target. The mathematical model was established by considering the geometric re... A new method uses a linear array that takes advantage of underwater physical sound fields to estimate the velocity of an underwater moving target. The mathematical model was established by considering the geometric relationship between the moving target installed with only two transducers to radiate sound of different frequencies and the linear array. In addition, deterministic maximum likelihood and signal phase matching algorithms were introduced to effectively find the directions of arrival (DOAs) of the sound sources of the two transducers installed on the target. Factors causing velocity measurement errors were considered. To track the target, a linear array with a compass, a pressure transducer, a signal conditioner and a digital recorder was configured. Relevant requirements for the array parameters were derived. The simulation showed that a 16-element array with an aperture of less than lm can measure velocity with relative error of no more', than 4% when including typical system errors. Anechoic pool and reservoir experiments confirmed these results. 展开更多
关键词 underwater velocity measurement linear array direction of arrival (DOA) deterministicmaximum likelihood signal phase matching
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Internal Flow Field Measurement of Gas Turbine Based on Optical Flow Method
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作者 Chengyang Li 《Journal of Applied Mathematics and Physics》 2022年第6期1910-1917,共8页
The in-cylinder flow field of the internal combustion engine is an important factor affecting the quality and combustion quality of the fuel mixture in the cylinder. In order to calculate the high-precision flow field... The in-cylinder flow field of the internal combustion engine is an important factor affecting the quality and combustion quality of the fuel mixture in the cylinder. In order to calculate the high-precision flow field, the paper presents a flow field calculation method based on the optical flow algorithm. The motion of the point was calculated using the change in pixel intensity within two temporally adjacent frame images. The results show the high accuracy and resolution of the flow field at small displacement conditions. 展开更多
关键词 Optical Flow Method Particle Image velocity measurement Flow Field Calculation
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Simutaneous radar imaging and velocity measuring with step frequency waveforms 被引量:4
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作者 Yuan Haotian Wen Shuliang Cheng Zhen 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第4期741-747,共7页
The principle and method of both radar target imaging and velocity measurement simultaneously based on step frequency waveforms is presented. Velocity compensation is necessary in order to obtain the good High resolut... The principle and method of both radar target imaging and velocity measurement simultaneously based on step frequency waveforms is presented. Velocity compensation is necessary in order to obtain the good High resolution range profile since this waveform is greatly sensitive to the Doppler shift. The velocity measurement performance of the four styles is analyzed with two pulse trains consisted of positive and negative step frequency waveforms. The velocity of targets can be estimated first coarsely by using the pulse trains with positive-positive step frequency combination, and then fine by positive-negative combination. Simulation results indicate that the method can accomplish the accurate estimation of the velocity with efficient computation and good anti-noise performance and obtain the good HRRP simultaneously. 展开更多
关键词 high resolution radar step frequency waveform velocity measuring high resolution range profile.
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Measuring the velocity of sand particles in an air/particle two-phase flow:A comparison of several commonly used methods 被引量:2
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作者 Zhibao Dong GuangQiang Qian WanYin Luo HongTaoWang 《Research in Cold and Arid Regions》 2010年第3期185-197,共13页
The velocity of blown sand particles is an important parameter in aeolian movement (a special case of gas particle two-phase flow) and has ever been a topic of interest. At present, several techniques have been appl... The velocity of blown sand particles is an important parameter in aeolian movement (a special case of gas particle two-phase flow) and has ever been a topic of interest. At present, several techniques have been applied in measuring velocity of the blown sand particles. This paper reviews the measurement results of several commonly used methods: photoelectric cell method, high-speed photographic method, Particle Dynamics Analyzer (PDA) method and Particle Image Velocimetry (PIV) method. Photoelectric cell method, high-speed photograph method and PDA method are useful in studying the velocity distribution of particles. PIV is a whole-flow-field technique and a useful tool to study the average velocity field in a target area. These methods got some similar results but considerable differences also exist. They have come to similar conclusions on the velocity distributions at a single height but direct measurement results with respect to the velocity distribution very close to the surface are still scarce except some PDA results. The magnitude of measured mean particle velocity differs greatly. The relationship obtained by different methods between mean particle velocity and wind velocity, particle size and possibly other influencing factors also differs considerably. Although several authors have proposed similar power functions to describe the variation with height of the mean particle velocity, the predicted results have wide differences. Each technique is based on some unique principles, and has its advantages and disad- vantages. To make full use of different techniques, a lot of work needs be done to validate them. Developing a reliable technique to measure the velocity of blown particles is still a necessary task in aeolian research. 展开更多
关键词 aeolian transport velocity of particles measurement techniques
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Analysis of the Intrinsic Uncertainties in the Laser-Driven Iron Hugoniot Experiment Based on the Measurement of Velocities
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作者 章欢 段晓溪 +6 位作者 张琛 刘浩 张惠鸽 薛全喜 叶青 王哲斌 蒋刚 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第8期91-95,共5页
One of the most challenging tasks in the laser-driven Hugoniot experiment is how to increase the reproducibility and precision of the experimental data to meet the stringent requirement in validating equation of state... One of the most challenging tasks in the laser-driven Hugoniot experiment is how to increase the reproducibility and precision of the experimental data to meet the stringent requirement in validating equation of state models. In such cases, the contribution of intrinsic uncertainty becomes important and cannot be ignored. A detailed analysis of the intrinsic uncertainty of the aluminum-iron impedance-match experiment based on the measurement of velocities is presented. The influence of mirror-reflection approximation on the shocked pressure of Fe and intrinsic uncertainties from the equation of state uncertainty of standard material are quantified, Furthermore, the comparison of intrinsic uncertainties of four different experimental approaches is presented. It is shown that, compared with other approaches including the most widely used approach which relies on the measurements of the shock velocities of AI and Fe, the approach which relies on the measurement of the particle velocity of Al and the shock velocity of Fe has the smallest intrinsic uncertainty, which would promote such work to significantly improve the diagnostics precision in such an approach. 展开更多
关键词 of is Analysis of the Intrinsic Uncertainties in the Laser-Driven Iron Hugoniot Experiment Based on the measurement of Velocities in Al on
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Comparison of methods for turbulence Doppler frequency shift calculation in Doppler reflectometer
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作者 仲小明 邹晓岚 +16 位作者 周楚 刘阿娣 庄革 冯喜 张津 季佳旭 范泓锐 刘深 王士凡 高刘天 史文祥 兰涛 李弘 谢锦林 毛文哲 刘子奚 刘万东 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第9期42-50,共9页
The Doppler reflectometer(DR),a powerful diagnostic for the plasma perpendicular velocity(u⊥)and turbulence measurement,has been widely used in various fusion devices.Many efforts have been put into extracting the Do... The Doppler reflectometer(DR),a powerful diagnostic for the plasma perpendicular velocity(u⊥)and turbulence measurement,has been widely used in various fusion devices.Many efforts have been put into extracting the Doppler shift from the DR signal.There are several commonly used methods for Doppler shift extraction,such as the phase derivative,the center of gravity,and symmetric fitting(SFIT).However,the strong zero-order reflection component around 0 kHz may interfere with the calculation of the Doppler shift.To avoid the influence of the zerofrequency peak,the asymmetric fitting(AFIT)method was designed to calculate the Doppler shift.Nevertheless,the AFIT method may lead to an unacceptable error when the Doppler shift is relatively small compared to the half width at half maximum(HWHM).Therefore,an improved method,which can remove the zero-frequency peak and fit the remaining Doppler peak with a Gaussian function,is devised to extract the Doppler shift.This method can still work reliably whether the HWHM is larger than the Doppler shift or not. 展开更多
关键词 perpendicular velocity measurement Doppler reflectometer Doppler shift
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