This paper concentrates on super-resolution imaging of the ship target under the sparse aperture situation.Firstly,a multi-static configuration is utilized to solve the coherent processing interval(CPI)problem caused ...This paper concentrates on super-resolution imaging of the ship target under the sparse aperture situation.Firstly,a multi-static configuration is utilized to solve the coherent processing interval(CPI)problem caused by the slow-speed motion of ship targets.Then,we realize signal restoration and image reconstruction with the alternating direction method of multipliers(ADMM).Furthermore,we adopt the interferometric technique to produce the three-dimensional(3D)images of ship targets,namely interferometric inverse synthetic aperture radar(InISAR)imaging.Experiments based on the simulated data are utilized to verify the validity of the proposed method.展开更多
In this paper,a multi-static system working in an active way is made up of ionospheric oblique backscatter sounding system(IOBSS)and two separate receiving stations,which adopts discontinuous wave mechanism.We have ad...In this paper,a multi-static system working in an active way is made up of ionospheric oblique backscatter sounding system(IOBSS)and two separate receiving stations,which adopts discontinuous wave mechanism.We have advanced a new model that contains skywave condition to locate over-the-horizon targets.We use a single quasi-parabolic(QP)ionosphere model and an analytic ray-tracing program to obtain the coordinate registration(CR)index,which changes skywave group range to ground range.Also,IOBSS and other two receiving stations use this distance information to locate the target which is far away from the system.The analytic expression for the geometric dilution of precision(GDOP)under different station deployments are obtained,which shows GDOP is influenced by the system measurement precision,the stations'coordinates,and CR index.By computer simulation,we find that GDOP of isosceles right triangle deployment is smaller than that of line deployment and location precision will be improved with increasing base line length.The results indicate that this model is practicable with an acceptable range of error(less than 500 m under certain conditions in this paper).展开更多
Generally,to apply the MUltiple SIgnal Classification(MUSIC)algorithm for the rapid imaging of small objects,complete elements of the multi-static response(MSR)matrix must be collected.However,in some real-world appli...Generally,to apply the MUltiple SIgnal Classification(MUSIC)algorithm for the rapid imaging of small objects,complete elements of the multi-static response(MSR)matrix must be collected.However,in some real-world applications in microwave imaging,diagonal elements of theMSRmatrix are unknown.Nevertheless,it is possible to obtain imaging results using a traditional approach but theoretical reason of the applicability has not been investigated yet.In this paper,we consider the application of MUSIC for a fast identification of small objects from collected MSR matrix in both transverse magnetic(TM)and transverse electric(TE)polarizations.In order to examine the applicability,fundamental limitation,and various properties of MUSIC,we establish mathematical structure of the three imaging functions and explore that the main factors of the imaging functions are Bessel function of order zero,one,and two.The established structures demonstrate why the existence and location of small objects can be retrieved via MUSIC without the diagonal elements of the MSR matrix.Results of numerical simulations with noise-corrupted synthetic data are also provided to support the identified structures.展开更多
基金This work was supported by the National Natural Science Foundation of China(61871146).
文摘This paper concentrates on super-resolution imaging of the ship target under the sparse aperture situation.Firstly,a multi-static configuration is utilized to solve the coherent processing interval(CPI)problem caused by the slow-speed motion of ship targets.Then,we realize signal restoration and image reconstruction with the alternating direction method of multipliers(ADMM).Furthermore,we adopt the interferometric technique to produce the three-dimensional(3D)images of ship targets,namely interferometric inverse synthetic aperture radar(InISAR)imaging.Experiments based on the simulated data are utilized to verify the validity of the proposed method.
基金Supported by the National High Technology Research and Development Program of China (863 Program) (2009AAXXX1302)
文摘In this paper,a multi-static system working in an active way is made up of ionospheric oblique backscatter sounding system(IOBSS)and two separate receiving stations,which adopts discontinuous wave mechanism.We have advanced a new model that contains skywave condition to locate over-the-horizon targets.We use a single quasi-parabolic(QP)ionosphere model and an analytic ray-tracing program to obtain the coordinate registration(CR)index,which changes skywave group range to ground range.Also,IOBSS and other two receiving stations use this distance information to locate the target which is far away from the system.The analytic expression for the geometric dilution of precision(GDOP)under different station deployments are obtained,which shows GDOP is influenced by the system measurement precision,the stations'coordinates,and CR index.By computer simulation,we find that GDOP of isosceles right triangle deployment is smaller than that of line deployment and location precision will be improved with increasing base line length.The results indicate that this model is practicable with an acceptable range of error(less than 500 m under certain conditions in this paper).
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(NRF-2020R1A2C1A01005221).
文摘Generally,to apply the MUltiple SIgnal Classification(MUSIC)algorithm for the rapid imaging of small objects,complete elements of the multi-static response(MSR)matrix must be collected.However,in some real-world applications in microwave imaging,diagonal elements of theMSRmatrix are unknown.Nevertheless,it is possible to obtain imaging results using a traditional approach but theoretical reason of the applicability has not been investigated yet.In this paper,we consider the application of MUSIC for a fast identification of small objects from collected MSR matrix in both transverse magnetic(TM)and transverse electric(TE)polarizations.In order to examine the applicability,fundamental limitation,and various properties of MUSIC,we establish mathematical structure of the three imaging functions and explore that the main factors of the imaging functions are Bessel function of order zero,one,and two.The established structures demonstrate why the existence and location of small objects can be retrieved via MUSIC without the diagonal elements of the MSR matrix.Results of numerical simulations with noise-corrupted synthetic data are also provided to support the identified structures.
文摘介绍了碳纳米管(Carbon Nano Tube, CNT)冷阴极X射线源及分布式X射线源的概念、构成和发展历史,总结了CNT冷阴极的3个特点:(1)结构简单、体积小,易于高密度集成;(2)常温工作、控制简单且无热管理问题;(3)阴极电流和工作寿命达到应用需求。详细介绍了国内外冷阴极分布式X射线源的研究进展情况。国外多个单位的CNT冷阴极分布式X射线源、医疗静态三维成像系统及静态安检CT;国内的研究和应用已处于领先地位,实现了焦点数量从7个增加到256个,阳极工作电流从7 mA提高到50 mA,阳极电压最高200 kV。工作寿命达数万小时的CNT冷阴极分布式X射线源已产品化,且已在安检、工业和医疗领域取得了积极的应用:安检静态CT检测通道尺寸超过1 m,检测速度已经达到1.5 m/s,通过中国民航和欧洲民航会议(European Civil Aviation Conference, ECAC)最高等级3.1的认证,已投入运行近百套;高速工业CT可实现10 f/s的高速成像,在高速流场分析、烧蚀过程分析及运动疲劳分析等过程分析中发挥重要作用;牙科3D成像设备获得美国食品药物管理局(Food and Drug Administration, FDA)认证并销售近百套;移动式胸部层析成像在北美放射学年会(Radiological Society of North America, RSNA)获得较高关注度。随着CNT冷阴极分布式X射线源的技术特性日益清晰,静态三维成像系统技术的优势得到验证,国际知名企业纷纷加入研究队伍,标志着该项技术及应用即将步入快速发展阶段。
