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Measuring the kinetic parameters of saltating sand grains using a high-speed digital camera 被引量:4
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作者 ZHANG Yang WANG Yuan JIA Pan 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第6期1137-1143,共7页
A high-speed digital camera is used to record the saltation of three sand samples(diameter range:300–500,200–300 and100–125μm).This is followed by an overlapping particle tracking algorithm to reconstruct the salt... A high-speed digital camera is used to record the saltation of three sand samples(diameter range:300–500,200–300 and100–125μm).This is followed by an overlapping particle tracking algorithm to reconstruct the saltating trajectory and the differential scheme to abstract the kinetic parameters of saltating grains.The velocity results confirm the propagating feature of saltation in maintaining near-face aeolian sand transport.Moreover,the acceleration of saltating sand grains was obtained directly from the reconstructed trajectory,and the results reveal that the climbing stage of the saltating trajectory represents an critical process of energy transfer while the sand grains travel through air. 展开更多
关键词 high-speed digital camera sand saltation particle tracking kinetic parameters
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Research on digital twin technology and its application in intelligent operation and maintenance of highspeed railway infrastructure
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作者 Yi liu Ping Li +3 位作者 Boqing Feng Peifen Pan Xueying Wang Qiliang Zhao 《Railway Sciences》 2024年第6期746-763,共18页
Purpose–This paper analyzes the application of digital twin technology in the field of intelligent operation and maintenance of high-speed railway infrastructure from the perspective of top-level design.Design/method... Purpose–This paper analyzes the application of digital twin technology in the field of intelligent operation and maintenance of high-speed railway infrastructure from the perspective of top-level design.Design/methodology/approach–This paper provides a comprehensive overview of the definition,connotations,characteristics and key technologies of digital twin technology.It also conducts a thorough analysis of the current state of digital twin applications,with a particular focus on the overall requirements for intelligent operation and maintenance of high-speed railway infrastructure.Using the Jinan Yellow River Bridge on the Beijing–Shanghai high-speed railway as a case study,the paper details the construction process of the twin system from the perspectives of system architecture,theoretical definition,model construction and platform design.Findings–Digital twin technology can play an important role in the whole life cycle management,fault prediction and condition monitoring in the field of high-speed rail operation and maintenance.Digital twin technology is of great significance to improve the intelligent level of high-speed railway operation and management.Originality/value–This paper systematically summarizes the main components of digital twin railway.The general framework of the digital twin bridge is given,and its application in the field of intelligent operation and maintenance is prospected. 展开更多
关键词 System architecture digital twin Intelligent railway Beijing–shanghai high-speed railway Intelligent maintenance
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A Method to Improve Photographing Function of Common Digital Camera to Small Flowers and Fruits 被引量:1
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作者 洪亚平 张亚冰 《Agricultural Science & Technology》 CAS 2009年第6期105-107,共3页
[ Objective] The aim of this study was to solve the problem of photographing small flowers and fruits with a common digital camera in field. [Method] Firstly, the photographic mode of a common digital camera was set ... [ Objective] The aim of this study was to solve the problem of photographing small flowers and fruits with a common digital camera in field. [Method] Firstly, the photographic mode of a common digital camera was set as "macro" (or "soft snap" ) and "flash off". Secondly, the small flower or fruit was magnified with a magnifying glass, and then the magnified flower or fruit was automatically focused with the digital camera lens. After automatic focusing, the shutter button was pressed and the photograph finished. [Result] With this method, the clear inflo- rescence or floral photographs of Eragrostis pilosa ( Gramineae ) , Bidens biternata (Compositae) and Tribulus terrester (Zygophllaceae) were obtained in field. [ Conclusion] The optical system of a digital camera has been changed by the magnifying glass, which improves the photographic function of a common digital camera to small flowers and fruits, and also easily gets their clear photographs. 展开更多
关键词 digital camera Magnifying glass Photographing FLOWER FRUIT
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Estimation of Fractional Vegetation Cover Based on Digital Camera Survey Data and a Remote Sensing Model 被引量:6
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作者 HU Zhen-qi HE Fen-qin +4 位作者 YIN Jian-zhong LU Xia TANG Shi-lu WANG Lin-lin LI Xiao-jing 《Journal of China University of Mining and Technology》 EI 2007年第1期116-120,共5页
The objective of this paper is to improve the monitoring speed and precision of fractional vegetation cover (fc). It mainly focuses on fc estimation when fcmax and fcmin are not approximately equal to 100% and 0%, res... The objective of this paper is to improve the monitoring speed and precision of fractional vegetation cover (fc). It mainly focuses on fc estimation when fcmax and fcmin are not approximately equal to 100% and 0%, respectively due to using remote sensing image with medium or low spatial resolution. Meanwhile, we present a new method of fc estimation based on a random set of fc maximum and minimum values from digital camera (DC) survey data and a di- midiate pixel model. The results show that this is a convenient, efficient and accurate method for fc monitoring, with the maximum error -0.172 and correlation coefficient of 0.974 between DC survey data and the estimated value of the remote sensing model. The remaining DC survey data can be used as verification data for the precision of the fc estimation. In general, the estimation of fc based on DC survey data and a remote sensing model is a brand-new development trend and deserves further extensive utilization. 展开更多
关键词 fractional vegetation cover digital camera survey data dimidiate pixel model
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The Calibration of High-Speed Camera Imaging System for ELMs Observation on EAST Tokamak 被引量:1
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作者 FU Chao ZHONG Fangchuan +5 位作者 HU Liqun YANG Jianhua YANG Zhendong GAN Zaifu ZHANG Bin EAST Team 《Plasma Science and Technology》 SCIE EI CAS CSCD 2016年第9期884-889,共6页
A tangential fast visible camera has been set up in EAST tokamak for the study of edge MHD instabilities such as ELM. To determine the 3-D information from CCD images, Tsai's two-stage technique was utilized to calib... A tangential fast visible camera has been set up in EAST tokamak for the study of edge MHD instabilities such as ELM. To determine the 3-D information from CCD images, Tsai's two-stage technique was utilized to calibrate the high-speed camera imaging system for ELM study. By applying tiles of the passive stabilizers in the tokamak device as the calibration pattern, transformation parameters for transforming from a 3-D world coordinate system to a 2-D image coordinate system were obtained, including the rotation matrix, the translation vector, the focal length and the lens distortion. The calibration errors were estimated and the results indicate the reliability of the method used for the camera imaging system. Through the calibration, some information about ELM filaments, such as positions and velocities were obtained from images of H-mode CCD videos. 展开更多
关键词 CCD CALIBRATION H-MODE ELM filamentary structure high-speed camera
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Investigation of condition-induced bubble size and distribution in electroflotation using a high-speed camera 被引量:2
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作者 Ren Liuyi Zhang Yimin +3 位作者 Qin Wenqing Bao Shenxu Wang Peipei Yang Congren 《International Journal of Mining Science and Technology》 SCIE EI 2014年第1期7-12,共6页
In the flotation process, bubble is a key factor in studying bubble-particle interaction and fine particle flo- tation. Knowledge on size distribution of bubbles in a flotation system is highly important. In this stud... In the flotation process, bubble is a key factor in studying bubble-particle interaction and fine particle flo- tation. Knowledge on size distribution of bubbles in a flotation system is highly important. In this study, bubble distributions in different reagent concentrations, electrolyte concentrations, cathode apertures, and current densities in electroflotation are determined using a high-speed camera. Average bubble sizes under different conditions are calculated using Image-Pro@ Plus (Media Cybernetics@, MD, USA) and SigmaScan@ Pro (Systat Software, CA, USA) software. Results indicate that the average sizes of bubbles, which were generated through 38, 50, 74, 150, 250, 420, and 1000 μm cathode apertures, are 20.2, 29.5, 44.6, 59.2, 68.7, 78.5, and 88.8 μm, respectively. The optimal current density in electroflotation is 20 A/m2. Reagent and electrolyte concentrations, current density, and cathode aperture are important factors in controlling bubble size and nucleation. These factors also contribute to the control of fine- Particle flotation. 展开更多
关键词 high-speed camera Bubble Electroflotation Fine particle Bubble production and control
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Imaging simulation and analysis of attitude jitter effect on topographic mapping for lunar orbiter stereo optical cameras
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作者 CHEN Chen TONG Xiao-Hua +4 位作者 LIU Shi-Jie YE Zhen HUANG Chao-Wei WU Hao ZHANG Han 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2024年第5期722-730,共9页
The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo m... The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison. 展开更多
关键词 topographic mapping lunar orbiter stereo camera attitude jitter imaging simulation digital elevation model
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Positioning of Screw Holes Group Based on Digital Camera and Digital Control Drilling
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作者 FENGWenhao LIJiansong YANLi SUGuozhong YUANXiuxiao ZHONGShengzhang JIHuiming 《Geo-Spatial Information Science》 2004年第4期235-242,共8页
Positioning of screw holes is an important production procedure for steel construction connecting with bolts. In this paper, a new production method is presented, in which the digital camera is used for taking picture... Positioning of screw holes is an important production procedure for steel construction connecting with bolts. In this paper, a new production method is presented, in which the digital camera is used for taking pictures of screw holes and other techniques are advanced. This paper also indicates that the pixels of CCD chip in photogrammetry should be chosen as all geometric units in an image, such as interior elements and all kinds of distortions. The measure can also simplify the camera calibration for determining the size of non-square pixel. 展开更多
关键词 digital camera screw hoies digital drilling machine PHOTOGRAMMETRY multi-station photo- grammetry SELF-CALIBRATION bundle adjustment
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Evaluation of the Anterior Chamber Angle Structures in Perinatal Infants Using a Wide-Field Digital Fundus Camera
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作者 Xian ZHANG Dan-lan LUO +2 位作者 Bo CHEN Qiong-lei ZHONG Hong YANG 《Current Medical Science》 SCIE CAS 2022年第6期1305-1309,共5页
Objective This study aimed to evaluate the ability of a digital fundus camera to observe the development of the anterior chamber angle(ACA)in premature infants.Methods Forty-eight eyes of preterm infants(n=48)were exa... Objective This study aimed to evaluate the ability of a digital fundus camera to observe the development of the anterior chamber angle(ACA)in premature infants.Methods Forty-eight eyes of preterm infants(n=48)were examined by a digital fundus camera to observe the development of the ACA.ACA grading was performed based on the visualization of the anterior chamber structures according to the Scheie Angle Depth Evaluating System.Results ACA images from all 48 infants were successfully acquired using RetCam3.The corrected gestational age ranged from 30 weeks to 49 weeks,which covered the period from 2 months preterm to>2 months post-term.As the corrected gestational age increased,the corrected gestational age grading was significantly decreased.The mean corrected gestational ages of the infants corresponding to the ACA classification from grade IV to grade 0 were 32.75±1.89,37.20±1.30,39.75±2.38,40.56±2.24,and 44.23±2.14 weeks,respectively,which were all significantly different(P<0.05).The regression analysis showed a linear correlation between the grading of the ACA and the corrected gestational age(R2=0.724,P=0.0001).Conclusion The ACA of a full-term newborn can be fully detected and evaluated by a digital fundus camera.For premature infants,part of the ACA is not visible physiologically;however,it should not be misdiagnosed as angle closure or a narrow angle. 展开更多
关键词 digital fundus camera anterior chamber angle GLAUCOMA INFANT
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Enhancement of Frame-rate Using Digital Camera
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作者 LIU Wen-jing HUANG Yao-xiong XIONG Ping 《Semiconductor Photonics and Technology》 CAS 2007年第1期80-82,88,共4页
Frame rate is corresponding to the temporal resolution and the number of the pixels of the picture is corresponding to the spatial resolution. They are both very important for the researchers. The ideal image analysis... Frame rate is corresponding to the temporal resolution and the number of the pixels of the picture is corresponding to the spatial resolution. They are both very important for the researchers. The ideal image analysis and processing system should have high spatiotemporal characteristics, which is much expensive in practical use. A new method to enhance dynamic frame rate using multi-digital camera(DC) is proposed and the result shows that it could increase the frame rate effectively and decreases the cost in practical use. 展开更多
关键词 frame rate temporal resolution digital camera
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Spectral Measurement of Atmospheric Pressure Plasma by Means of Digital Camera
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作者 葛袁静 张广秋 +1 位作者 刘益民 赵志发 《Plasma Science and Technology》 SCIE EI CAS CSCD 2002年第1期1107-1112,共6页
A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pres- sure. The experimental results showed ... A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pres- sure. The experimental results showed that: (1) The uniformity of electron temperature in space depends on discharge condition and structure of web electrode. For a certain web electrode the higher the discharge voltage is, the more uniform distribution of electron temperature in space will be. For a certain discharge the finer and denser the holes on web electrode are, the more uniform distribution of electron temperature in space will be (2). Digital camera is an available equipment to measure some behaviors of the plasma working at atmospheric pressure. 展开更多
关键词 Spectral Measurement of Atmospheric Pressure Plasma by Means of digital camera
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1分钟,给你的相片做美容——Digital Camera Tools合家欢
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作者 周晶 《数字世界》 2002年第12期70-71,共2页
用数码相机拍得的相片,在保存和网络传输方面有不容置疑的优越性,因此越来越多的人开始使用数码相机。但是我们不得不承认,它在成像质量方面还不能完全替代传统的相机。在你的数码像册里有没有一些太亮、太暗或者有杂点的问题照片呢?不... 用数码相机拍得的相片,在保存和网络传输方面有不容置疑的优越性,因此越来越多的人开始使用数码相机。但是我们不得不承认,它在成像质量方面还不能完全替代传统的相机。在你的数码像册里有没有一些太亮、太暗或者有杂点的问题照片呢?不要以为它们没救了哦,看了今天介绍的方法你就会知道,其实要给它们做美容一点都不难,只要一分钟就可以让你的相片白净又明亮! 咱们要用的这一系列美容工具叫做:Digital camera Tools(本文介绍的软件都可在http://www.mediachance.com/digicam/下载),这些简单又实用的小工具基本上可以解决数码相片中存在的大部分常见问题,比如:偏色、亮度不正常、有杂点等,对传统相片中的类似问题也有一定的作用。每一种工具都有它的适用范围,如果你的照片不在其适用范围之内,或者原本就拍得不错的话,那你可能就看不到太大的差别哦! 展开更多
关键词 相片 digital camera TOOLS 数码相机 调色 去斑
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非常好色 明基BENQ Digital Camera 300mini
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《新潮电子》 2002年第1期20-20,共1页
关键词 明基BENQ digital camera 300mini 数码相机 内存 外形设计
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特工装备 007Digital Camera
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《电脑应用文萃》 2004年第2期25-25,共1页
关键词 数码相机 007 digital camera 光学变焦 数码变焦
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Digital Camera影像视觉牵手搜狐举办中国首届无人机摄影大赛获奖作品选登
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《影像视觉》 2015年第12期12-19,共8页
ANDERS ANDERSSON_海外组一等奖我想一直想用无人机拍这样的自拍照片,于是邀请了我的邻居朋友Tobias在瑞典Ljungby的一个社区摆出这样的姿势。我们在泳池开放时间提前一个小时到达,大概半个小时后完成了拍摄。我也很想在泳池里人多的时... ANDERS ANDERSSON_海外组一等奖我想一直想用无人机拍这样的自拍照片,于是邀请了我的邻居朋友Tobias在瑞典Ljungby的一个社区摆出这样的姿势。我们在泳池开放时间提前一个小时到达,大概半个小时后完成了拍摄。我也很想在泳池里人多的时候拍,但是考虑到会有一定的危险就没有实行。" 展开更多
关键词 digital camera 获奖作品选 影像视觉 里人 摄影大赛 广东省梅州市 繁星点点 花萼楼 大东 大埔县
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A Model for Estimating Total Forest Coverage with Ground-Based Digital Photography 被引量:5
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作者 GU Zhu-Jun ZENG Zhi-Yuan +5 位作者 SHI Xue-Zheng LI Lin D. C. WEINDORF ZHA Yong YU Dong-Sheng LIU YongoMei 《Pedosphere》 SCIE CAS CSCD 2010年第3期318-325,共8页
Vegetation fractional coverage (VFC) is one of the key indicators of vegetation distribution. In the work a measurement-based model was developed to derive total forest VFC (TG) as well as the VFC of trees (T) and shr... Vegetation fractional coverage (VFC) is one of the key indicators of vegetation distribution. In the work a measurement-based model was developed to derive total forest VFC (TG) as well as the VFC of trees (T) and shrub-grasses (G) separately in a subtropical forest area in Nanjing, China. Both upward and downward photographs were taken with a digital camera in 72 quadrats (10 m × 10 m each). Fifteen models were established and validated. Models jointly using both T and G performed better than those using the T and G separately. The best model, TG = T + G- 1.134 × T × G- 0.025 (R2 = 0.9115, P < 0.01, root mean squared error = 0.0789), is recommended for application. This model provides a good way to obtain total forest VFC values through taking tree and shrub-grass photos on ground below tree canopy rather than above tree canopy. 展开更多
关键词 digital camera 2-layer photography shrub-grasses trees
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Development of High-Speed On-Of Valves and Their Applications 被引量:3
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作者 He Wang Zhen Chen +2 位作者 Jiahai Huang Long Quan Bin Zhao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第4期21-41,共21页
With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components ... With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs. 展开更多
关键词 high-speed on-of valve digital hydraulic component Switching frequency Flow rate Innovative structure Intelligent material
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A survey of high-speed high-resolution current steering DACs 被引量:1
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作者 Xing Li Lei Zhou 《Journal of Semiconductors》 EI CAS CSCD 2020年第11期41-51,共11页
Digital to analog converters(DAC)play an important role as a bridge connecting the analog world and the digital world.With the rapid development of wireless communication,wideband digital radar,and other emerging tech... Digital to analog converters(DAC)play an important role as a bridge connecting the analog world and the digital world.With the rapid development of wireless communication,wideband digital radar,and other emerging technologies,better performing high-speed high-resolution DACs are required.In those applications,signal bandwidth and high-frequency linearity often limited by data converters are the bottleneck of the system.This article reviews the state-of-the-art technologies of high-speed and high-resolution DACs reported in recent years.Comparisons are made between different architectures,circuit implementations and calibration techniques along with the figure of merit(FoM)results. 展开更多
关键词 digital to analog converters high-speed high-resolution current steering
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Visualization of High-Speed Impact of Projectile in Granular Sheet with Destructive Collision of Particles 被引量:1
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作者 Chihiro Masaki Kojiro Suzuki Yasumasa Watanabe 《Journal of Flow Control, Measurement & Visualization》 2018年第3期136-151,共16页
The impact and penetration of a projectile in a particle-laden space, which are expected to have frequently occurred during the formation of the solar system and will occur in the case of an impact probe for future pl... The impact and penetration of a projectile in a particle-laden space, which are expected to have frequently occurred during the formation of the solar system and will occur in the case of an impact probe for future planetary exploration, were experimentally simulated by using the ballistic range. A two-dimensional sheet made from small glass beads or emery powder was formed by the free-falling device through a long slit in the test chamber evacuated down to about 35 Pa. A polycarbonate projectile of a hemi-sphere-cylinder or sphere shape with the mass and diameter about 4 g and 25 mm, respectively, was launched at the velocity up to 430 m/s, and the phenomena were observed by the high-speed camera at 20,000 fps. From a series of images, the bow-shock-wave-like laterally facing U-shaped pattern over the projectile and the absence of particles in the trail behind it were clearly seen. At the impact of the particles on the projectile surface, fine grains were formed due to the destructive collision and injected outward from the projectile. The images obtained by different lighting methods including the laser light sheet were compared. The effects of the particle diameter, its material and the impact velocity were also investigated. 展开更多
关键词 BALLISTIC Range IMPACT GRANULAR Flow COLLISION high-speed camera
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Visualization of High-Speed Impact of Penetrator into Icy Target 被引量:1
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作者 Kojiro Suzuki Kazuya Namba Yasumasa Watanabe 《Journal of Flow Control, Measurement & Visualization》 2016年第2期56-69,共14页
For application to exploration under the surface of icy objects in the solar system, the penetration of an impact probe into an icy target was experimentally simulated by using the ballistic range. Slender projectiles... For application to exploration under the surface of icy objects in the solar system, the penetration of an impact probe into an icy target was experimentally simulated by using the ballistic range. Slender projectiles with a cylindrical body and various nose shapes were tested at the impact velocity 130 - 420 m/s. The motion of the penetrator, fragmentation of ice and crater forming were observed by the high-speed camera. It revealed that the crown-shaped ejection was made for a short time after the impact and then the outward normal jet-like stream of ice pieces continued for much longer time. The concave shape of the crater was successfully visualized by pouring the plaster into it. The two-stage structure, the pit and the spall, was clearly confirmed. The rim was not formed around the crater. Observation of the crater surface and the ice around the trace of the penetrator shows that both crushing into smaller ice pieces and recompression into ice blocks are caused by the forward motion of the penetrator. In case of a body with a flow-through duct, ice pieces entering the inlet at the nose tip were ejected from the tail, resulting in relaxation of the impact force. The correlation of the penetration distance and the crater diameter with the impact velocity was investigated. 展开更多
关键词 PENETRATOR ICE IMPACT Crater Forming Ballistic Range high-speed camera
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