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A distributed cooperative guidance law for salvo attack of multiple anti-ship missiles 被引量:26
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作者 Zhang Youan Wang Xingliang Wu Huali 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2015年第5期1438-1450,共13页
The consensus problem of impact time is addressed for multiple anti-ship missiles. A new distributed cooperative guidance law with the form of biased proportional navigation guidance (BPNG) is presented. The propose... The consensus problem of impact time is addressed for multiple anti-ship missiles. A new distributed cooperative guidance law with the form of biased proportional navigation guidance (BPNG) is presented. The proposed guidance law employs the available measurements of relative impact time error as the feedback information to achieve the consensus of impact time among mis- siles and, by exploiting the special structure of the biased cooperative control term, it can handle the seeker's field-of-view (FOV) constraint. The proposed scheme ensures convergence to consensus of impact time under either fixed or switching sensing/communication network, and the topological requirements are less restrictive than those in the existing results. Numerical examples are provided to illustrate the effectiveness of the proposed guidance law. 展开更多
关键词 COOPERATIVE DISTRIBUTED field-of-view constraint Missile guidance Missile trajectory control
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Integrated cooperative guidance framework and cooperative guidance law for multi-missile 被引量:21
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作者 Jianbo ZHAO Shuxing YANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2018年第3期546-555,共10页
An integrated cooperative guidance framework for multi-missile cooperatively attacking a single stationary target is proposed in this paper by combining both the centralized and decentralized communication topologies.... An integrated cooperative guidance framework for multi-missile cooperatively attacking a single stationary target is proposed in this paper by combining both the centralized and decentralized communication topologies. Once missiles are distributed into several groups, missiles within a single group communicate with the centralized leader-follower framework, while the leaders from different groups communicate using the nearest-neighbor topology. To implement the integrated cooperative guidance framework, a group of Finite-Time Cooperative Guidance(FTCG) laws considering the saturation constraint on FOV(FTCG-FOV) are firstly derived within the centralized leader-follower framework to satisfy the communication topology of missiles in a single group.Then, an improved sequential approach is developed to adapt the FTCG-FOV to satisfy the communication topology between groups. The numerical simulations demonstrate the effectiveness and high efficiency of the integrated cooperative guidance framework and the cooperative guidance laws, as well as the superiority of the developed sequential approach. 展开更多
关键词 COOPERATIVE field-of-view constraint FINITE-TIME FRAMEWORK Missile guidance Multi-missiles
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带有导引头视场限制的攻击时间控制导引律 被引量:14
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作者 马国欣 张友安 《弹道学报》 CSCD 北大核心 2013年第2期6-11,27,共7页
针对导弹机动飞行中的导引头视场受限问题,从导引头目标视角的动力学方程出发,通过在比例导引律基础上附加反馈项并利用余弦函数的非线性特性,设计了一种带有攻击时间控制及导引头视场限制的反舰导弹末制导律。采用Lyapunov稳定性理论,... 针对导弹机动飞行中的导引头视场受限问题,从导引头目标视角的动力学方程出发,通过在比例导引律基础上附加反馈项并利用余弦函数的非线性特性,设计了一种带有攻击时间控制及导引头视场限制的反舰导弹末制导律。采用Lyapunov稳定性理论,分析了闭环导引系统的稳定性。相比于切换逻辑的方法,这种直接设计导引律的方法避免了制导指令在不同导引律切换时的瞬间跳变。实际目标的机动使得攻击时间的控制精度变差,甚至导致导弹脱靶。对此,按照期望的攻击时间实时解算导弹与目标的预测遭遇点,并以遭遇点信息制导导弹,从而解决了目标机动情况下的多约束制导问题。仿真结果表明,本文方法是有效的。 展开更多
关键词 导弹 制导 稳定性 攻击时间 视场
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数字全息中利用图像拼接测量大物体的三维形貌 被引量:13
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作者 冯忠耀 贾昉 +1 位作者 周景会 忽满利 《中国激光》 EI CAS CSCD 北大核心 2008年第12期2017-2021,共5页
为扩大数字全息的测量视场,使数字全息可以应用于大物体三维形貌的测量,利用菲涅耳离轴数字全息,让照明光依次照明物体的各个区域并分别记录全息图,利用精密电控旋转台精确控制参考光的入射角以保证每次记录时物参角不变,通过参考光入... 为扩大数字全息的测量视场,使数字全息可以应用于大物体三维形貌的测量,利用菲涅耳离轴数字全息,让照明光依次照明物体的各个区域并分别记录全息图,利用精密电控旋转台精确控制参考光的入射角以保证每次记录时物参角不变,通过参考光入射角的变化量确定物体不同被照明区域之间的位置关系,对获得的物体去包裹的相位图进行拼接,进而得到整个物体的三维形貌。利用该方法测量了大小为11 cm×19 cm的石膏嘴的三维形貌,图像拼接的绝对拼接误差远小于1.14 mm,高度测量误差约为0.5 mm,实验结果说明这种测量方法能够有效地扩大数字全息测量物体三维形貌的视场并且具有和横向分辨率相当的拼接精度。 展开更多
关键词 信息光学 形貌测量 数字全息 图像拼接 视场
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Optimal three-dimensional impact time guidance with seeker’s field-of-view constraint 被引量:10
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作者 Shaoming HE Chang-Hun LEE +1 位作者 Hyo-Sang SHIN Antonios TSOURDOS 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第2期240-251,共12页
This paper proposes a new three-dimensional optimal guidance law for impact time control with seeker’s Field-of-View(FOV) constraint to intercept a stationary target. The proposed guidance law is devised in conjuncti... This paper proposes a new three-dimensional optimal guidance law for impact time control with seeker’s Field-of-View(FOV) constraint to intercept a stationary target. The proposed guidance law is devised in conjunction with the concept of biased Proportional Navigation Guidance(PNG). The guidance law developed leverages a nonlinear function to ensure the boundedness of velocity lead angle to cater to the seeker’s FOV limit. It is proven that the impact time error is nullified in a finite-time under the proposed method. Additionally, the optimality of the biased command is theoretically analyzed. Numerical simulations confirm the superiority of the proposed method and validate the analytic findings. 展开更多
关键词 Applied optimal control field-of-view constraint Impact time control Missile guidance Optimal error dynamics
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转台单侧多次偏置的旋转扫描模式的重建算法 被引量:8
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作者 陈明 张慧滔 +1 位作者 陈德峰 张朋 《无损检测》 2009年第1期29-34,共6页
在用短的线阵探测器检测大尺寸物体时,人们提出了多种扫描模式,以扩大扫描视野,其中RT(rotation-translation),即旋转加平移扫描模式在工程上较为实用。针对CT转台单侧多次偏置的RT扫描模式,提出了反投影滤波型的重建算法。该算法可以... 在用短的线阵探测器检测大尺寸物体时,人们提出了多种扫描模式,以扩大扫描视野,其中RT(rotation-translation),即旋转加平移扫描模式在工程上较为实用。针对CT转台单侧多次偏置的RT扫描模式,提出了反投影滤波型的重建算法。该算法可以直接重建CT图像,避免了已有算法所需要的数据重排,因而提高了计算效率和图像空间分辨力,使图像重建所需的投影数据减少约一半,从而在相同的旋转和平移次数下有效地扩大了扫描视野。实际CT扫描数据验证了重建算法的正确性。 展开更多
关键词 重建算法 RT扫描模式 转台偏置 扫描视野 反投影滤波
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基于双重体光栅的波导显示系统视场扩展研究 被引量:6
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作者 王闯 沈忠文 +2 位作者 翁一士 张宇宁 王保平 《光学学报》 EI CAS CSCD 北大核心 2022年第7期257-264,共8页
体全息波导显示系统的视场角受限于光栅衍射响应带宽,无法满足人们对大视场显示的需求。为扩展波导显示视场角,基于严格耦合波理论模型分析了波导显示视场角的影响因素,进一步提出了一种可有效扩展衍射响应带宽的双重体光栅波导结构,通... 体全息波导显示系统的视场角受限于光栅衍射响应带宽,无法满足人们对大视场显示的需求。为扩展波导显示视场角,基于严格耦合波理论模型分析了波导显示视场角的影响因素,进一步提出了一种可有效扩展衍射响应带宽的双重体光栅波导结构,通过变角度分次曝光法完成光栅制备,并搭建全息波导显示系统。成像结果表明,该显示系统的水平和竖直视场角可分别扩展至33.4°和22.6°,对角线视场角为40.3°。 展开更多
关键词 光学器件 全息波导 视场角 双重体光栅
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Large-field objective lens for multi-wavelength microscopy at mesoscale and submicron resolution
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作者 Xin Xu Qin Luo +7 位作者 Jixiang Wang Yahui Song Hong Ye Xin Zhang Yi He Minxuan Sun Ruobing Zhang Guohua Shi 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2024年第6期41-56,共16页
Conventional microscopes designed for submicron resolution in biological research are hindered by a limited field of view,typically around 1 mm.This restriction poses a challenge when attempting to simultaneously anal... Conventional microscopes designed for submicron resolution in biological research are hindered by a limited field of view,typically around 1 mm.This restriction poses a challenge when attempting to simultaneously analyze various parts of a sample,such as different brain areas.In addition,conventional objective lenses struggle to perform consistently across the required range of wavelengths for brain imaging in vivo.Here we present a novel mesoscopic objective lens with an impressive field of view of 8 mm,a numerical aperture of 0.5,and a working wavelength range from 400 to 1000 nm.We achieved a resolution of 0.74μm in fluorescent beads imaging.The versatility of this lens was further demonstrated through high-quality images of mouse brain and kidney sections in a wide-field imaging system,a confocal laser scanning system,and a two-photon imaging system.This mesoscopic objective lens holds immense promise for advancing multi-wavelength imaging of large fields of view at high resolution. 展开更多
关键词 mesoscopic objective lens large field-of-view high resolution MULTI-WAVELENGTH wide-field microscopy confocal laser scanning microscopy
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Command filtered integrated estimation guidance and control for strapdown missiles with circular field of view
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作者 Wei Wang Jiaqi Liu +2 位作者 Shiyao Lin Baokui Geng Zhongjiao Shi 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第5期211-221,共11页
In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated... In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets. 展开更多
关键词 Integrated estimation guidance and control Circular field-of-view Time-varying integral barrier Lyapunov function Command filtered backstepping control Nonlinear adaptive control Extended state observer
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带视场角约束的导弹协同攻击两阶段制导律 被引量:6
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作者 史绍琨 赵久奋 尤浩 《战术导弹技术》 北大核心 2019年第6期82-90,共9页
针对多导弹协同攻击机动目标问题,提出了一种带视场角约束的导弹协同攻击两阶段制导律。第一阶段为攻击时间控制,通过在传统比例导引项中增加用于时间控制和视场角限制的偏置项,设计了一种视场角限制下带时间约束的偏置比例导引律,设计... 针对多导弹协同攻击机动目标问题,提出了一种带视场角约束的导弹协同攻击两阶段制导律。第一阶段为攻击时间控制,通过在传统比例导引项中增加用于时间控制和视场角限制的偏置项,设计了一种视场角限制下带时间约束的偏置比例导引律,设计的制导律形式简单易于控制;第二阶段为攻击落角控制,设计了一种对视场角限制的新型滑模面,并结合快速幂次趋近律,提出了一种视场角限制下攻击落角控制的有限时间滑模制导律,适用于攻击机动目标。同时,给出了两种制导律的切换条件,通过制导律的切换,完成对攻击时间和落角的控制,并达到了对视场角限制的目的。仿真结果表明,所提出的制导律能够控制多枚导弹以各自指定角度协同攻击目标,并且将导弹视场角限制在导引头视场角范围内,验证了该制导律的有效性和优越性。 展开更多
关键词 视场角 协同攻击 机动目标 落角约束 滑模控制 导弹
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Two-phase guidance law for impact time control under physical constraints 被引量:6
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作者 Yang TANG Xiaoping ZHU +1 位作者 Zhou ZHOU Fei YAN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2020年第11期2946-2958,共13页
An impact-time-control guidance law is required for the simultaneous attack of suicide attack unmanned aerial vehicles.Based on the nonlinear model,a two-phase guidance strategy is proposed.The impact time is derived ... An impact-time-control guidance law is required for the simultaneous attack of suicide attack unmanned aerial vehicles.Based on the nonlinear model,a two-phase guidance strategy is proposed.The impact time is derived in a simple analytical form of initial states and switching states,and it can be controlled by switching at an appropriate range.Firstly,a two-phase guidance law is designed to make the magnitude of the heading error decrease monotonically from its initial value to zero.And then,the feasible interval of the switching ranges and of the impact times under the acceleration constraint are given analytically in sequence.Furthermore,a general form of twophase guidance law is proposed,which allows the magnitude of the heading error to increase in the first phase,to improve the applicability of the methodology.Having the same structure as proportional navigation guidance with a time-varying gain,the proposed algorithms are simple and easy to implement.The corresponding feedback form is presented for realistic implementation.When a predefined impact time is taken within its permissible set,the constraints on the acceleration and fieldof-view will not be violated during the interception.Finally,simulations validate the effectiveness of the methodology in impact time control and salvo attack. 展开更多
关键词 Acceleration constraint field-of-view constraint Guidance Impact time control SWITCHING
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乘用车与两轮车事故特征分析和目标识别因素研究 被引量:6
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作者 张立存 苗强 耿冬冬 《汽车技术》 CSCD 北大核心 2020年第3期41-44,共4页
为探究自动紧急制动(AEB)系统在事故场景中的避障作用,基于中国交通事故深入研究(CIDAS)数据库,分析了乘用车与两轮车事故成因及典型场景,确定其分布特性,建立了碰撞前1 s两轮车与乘用车的相对位置分布情况,基于此对自动紧急制动系统进... 为探究自动紧急制动(AEB)系统在事故场景中的避障作用,基于中国交通事故深入研究(CIDAS)数据库,分析了乘用车与两轮车事故成因及典型场景,确定其分布特性,建立了碰撞前1 s两轮车与乘用车的相对位置分布情况,基于此对自动紧急制动系统进行了工程探索,结果表明,两轮车被检测到的概率随自动紧急制动系统视场角的增大而增大。对真实道路行驶数据的研究表明,电动自行车在与乘用车同向或反向行驶时易被识别为摩托车,横穿场景易漏检或归类为行人。 展开更多
关键词 两轮车事故 中国交通事故深入研究 自动紧急制动 视场角
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Deep learning-based magnetic resonance imaging reconstruction for improving the image quality of reduced-field-of-view diffusionweighted imaging of the pancreas 被引量:1
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作者 Yukihisa Takayama Keisuke Sato +3 位作者 Shinji Tanaka Ryo Murayama Nahoko Goto Kengo Yoshimitsu 《World Journal of Radiology》 2023年第12期338-349,共12页
BACKGROUND It has been reported that deep learning-based reconstruction(DLR)can reduce image noise and artifacts,thereby improving the signal-to-noise ratio and image sharpness.However,no previous studies have evaluat... BACKGROUND It has been reported that deep learning-based reconstruction(DLR)can reduce image noise and artifacts,thereby improving the signal-to-noise ratio and image sharpness.However,no previous studies have evaluated the efficacy of DLR in improving image quality in reduced-field-of-view(reduced-FOV)diffusionweighted imaging(DWI)[field-of-view optimized and constrained undistorted single-shot(FOCUS)]of the pancreas.We hypothesized that a combination of these techniques would improve DWI image quality without prolonging the scan time but would influence the apparent diffusion coefficient calculation.AIM To evaluate the efficacy of DLR for image quality improvement of FOCUS of the pancreas.METHODS This was a retrospective study evaluated 37 patients with pancreatic cystic lesions who underwent magnetic resonance imaging between August 2021 and October 2021.We evaluated three types of FOCUS examinations:FOCUS with DLR(FOCUS-DLR+),FOCUS without DLR(FOCUS-DLR−),and conventional FOCUS(FOCUS-conv).The three types of FOCUS and their apparent diffusion coefficient(ADC)maps were compared qualitatively and quantitatively.RESULTS FOCUS-DLR+(3.62,average score of two radiologists)showed significantly better qualitative scores for image noise than FOCUS-DLR−(2.62)and FOCUS-conv(2.88)(P<0.05).Furthermore,FOCUS-DLR+showed the highest contrast ratio and 600 s/mm^(2)(0.72±0.08 and 0.68±0.08)and FOCUS-DLR−showed the highest CR between cystic lesions and the pancreatic parenchyma for the b-values of 0 and 600 s/mm2(0.62±0.21 and 0.62±0.21)(P<0.05),respectively.FOCUS-DLR+provided significantly higher ADCs of the pancreas and lesion(1.44±0.24 and 3.00±0.66)compared to FOCUS-DLR−(1.39±0.22 and 2.86±0.61)and significantly lower ADCs compared to FOCUS-conv(1.84±0.45 and 3.32±0.70)(P<0.05),respectively.CONCLUSION This study evaluated the efficacy of DLR for image quality improvement in reduced-FOV DWI of the pancreas.DLR can significantly denoise images without prolonging the scan time or decreasing the spatial resolu 展开更多
关键词 Deep learning-based reconstruction Magnetic resonance imaging Reduced field-of-view Diffusion-weighted imaging PANCREAS
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Atmospheric Correction of SeaWiFS Data for the Retrieval of SuspendedSediment in East China Coastal Waters 被引量:3
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作者 廖迎娣 张玮 P.Y.Deschamps 《China Ocean Engineering》 SCIE EI 2005年第2期225-234,共10页
The data of SeaWiFS (Sea-Viewing Wide Field-of-View Sensor), installed on SeaStar, has been used to generate SSC (suspended sediment concentration) of complex and turbid coastal waters in China. In view of the problem... The data of SeaWiFS (Sea-Viewing Wide Field-of-View Sensor), installed on SeaStar, has been used to generate SSC (suspended sediment concentration) of complex and turbid coastal waters in China. In view of the problems of the SeaDAS (SeaWiFS Data Analysis System) algorithm applied to China coastal waters, a new atmospheric correction algorithm is discussed, developed, and used for the SSC of East China coastal waters. The advantages of the new algorithm are described through the comparison of the results from different algorithms. 展开更多
关键词 suspended sediment concentration Sea-viewing Wide field-of-view Sensor suspended sediment atmospheric correction China coastal waters
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Understanding wide field-of-view flat lenses:an analytical solution[Invited]
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作者 杨帆 安森松 +3 位作者 Mikhail Y.Shalaginov 张华亮 胡崛隽 古田 《Chinese Optics Letters》 SCIE EI CAS CSCD 2023年第2期111-118,共8页
Wide field-of-view(FOV)optics are widely used in various imaging,display,and sensing applications.Conventional wide FOV optics rely on complicated lens assembly comprising multiple elements to suppress coma and other ... Wide field-of-view(FOV)optics are widely used in various imaging,display,and sensing applications.Conventional wide FOV optics rely on complicated lens assembly comprising multiple elements to suppress coma and other Seidel aberrations.The emergence of flat optics exemplified by metasurfaces and diffractive optical elements(DOEs)offers a promising route to expand the FOV without escalating complexity of optical systems.To date,design of large FOV flat lenses has been relying upon iterative numerical optimization.Here,we derive,for the first time,to the best of our knowledge,an analytical solution to enable computationally efficient design of flat lenses with an ultra-wide FOV approaching 180°.This analytical theory further provides critical insights into working principles and otherwise non-intuitive design trade-offs of wide FOV optics. 展开更多
关键词 metasurface metalens field-OF-view
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Near-Range Large Field-of-View Three-Dimensional Photon-Counting Imaging with a Single-Pixel Si-Avalanche Photodiode 被引量:3
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作者 Guang-Yue Shen Tian-Xiang Zheng +4 位作者 Bing-Cheng Du Yang Lv E Wu Zhao-Hui Li Guang Wu 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第11期38-41,共4页
Large field-of-view(FoV) three-dimensional(3 D) photon-counting imaging is demonstrated with a single-pixel single-photon detector based on a Geiger-mode Si-avalanche photodiode. By removing the collecting lens(C... Large field-of-view(FoV) three-dimensional(3 D) photon-counting imaging is demonstrated with a single-pixel single-photon detector based on a Geiger-mode Si-avalanche photodiode. By removing the collecting lens(CL)before the detector, the FoV is expanded to ±10°. Thanks to the high detection efficiency, the signal-to-noise ratio of the imaging system is as high as 7.8 dB even without the CL when the average output laser pulse energy is about 0.45 pJ/pulse for imaging the targets at a distance of 5 m. A 3 D image overlaid with the reflectivity data is obtained according to the photon-counting time-of-flight measurement and the return photon intensity. 展开更多
关键词 Near-Range Large field-of-view Three-Dimensional Photon-Counting Imaging with a Single-Pixel Si-Avalanche Photodiode SI
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多孔全卷积网络的语义分割算法研究 被引量:3
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作者 戴伟达 霍智勇 +1 位作者 严邓涛 陈钊 《南京邮电大学学报(自然科学版)》 北大核心 2018年第4期96-102,共7页
全卷积网络(Fully Convolutional Network,FCN)中由于连续的最大池化和下采样操作造成特征分辨率急剧降低,使最终上采样恢复的特征图失去对图像的细节敏感性。文中采用多孔卷积替代全卷积网络中的标准卷积,从而使得卷积网络在计算特征... 全卷积网络(Fully Convolutional Network,FCN)中由于连续的最大池化和下采样操作造成特征分辨率急剧降低,使最终上采样恢复的特征图失去对图像的细节敏感性。文中采用多孔卷积替代全卷积网络中的标准卷积,从而使得卷积网络在计算特征响应时能精确控制图像的分辨率,同时在不增加参数数量以及计算量的前提下,有效地扩大了滤波器的感受野。数值实验表明,文中算法利用更多的上下文信息获取了更稠密的特征,有效地提高了分割精度。 展开更多
关键词 卷积神经网络 语义分割 最大池化 感受野 多孔卷积
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Flexible reduced field of view magnetic resonance imaging based on single-shot spatiotemporally encoded technique 被引量:1
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作者 李敬 蔡聪波 +3 位作者 陈林 陈颖 屈小波 蔡淑惠 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第10期629-637,共9页
In many ultrafast imaging applications, the reduced field-of-view(r FOV) technique is often used to enhance the spatial resolution and field inhomogeneity immunity of the images. The stationary-phase characteristic ... In many ultrafast imaging applications, the reduced field-of-view(r FOV) technique is often used to enhance the spatial resolution and field inhomogeneity immunity of the images. The stationary-phase characteristic of the spatiotemporallyencoded(SPEN) method offers an inherent applicability to r FOV imaging. In this study, a flexible r FOV imaging method is presented and the superiority of the SPEN approach in r FOV imaging is demonstrated. The proposed method is validated with phantom and in vivo rat experiments, including cardiac imaging and contrast-enhanced perfusion imaging. For comparison, the echo planar imaging(EPI) experiments with orthogonal RF excitation are also performed. The results show that the signal-to-noise ratios of the images acquired by the proposed method can be higher than those obtained with the r FOV EPI. Moreover, the proposed method shows better performance in the cardiac imaging and perfusion imaging of rat kidney, and it can scan one or more regions of interest(ROIs) with high spatial resolution in a single shot. It might be a favorable solution to ultrafast imaging applications in cases with severe susceptibility heterogeneities, such as cardiac imaging and perfusion imaging. Furthermore, it might be promising in applications with separate ROIs, such as mammary and limb imaging. 展开更多
关键词 magnetic resonance imaging spatiotemporal encoding single shot reduced field-of-view
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视场角限制下导弹协同攻击导引律设计 被引量:2
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作者 赵久奋 史绍琨 +1 位作者 尤浩 杨奇松 《国防科技大学学报》 EI CAS CSCD 北大核心 2019年第4期114-120,共7页
为实现多枚导弹协同攻击目标,提出视场角限制下攻击时间角度控制导引律。通过在传统比例导引上增加两项偏置项,推导出一种新型攻击时间和角度控制的导引律,并用Lyapunov理论证明其稳定性。针对导弹大机动下视场角可能超过导引头视场角... 为实现多枚导弹协同攻击目标,提出视场角限制下攻击时间角度控制导引律。通过在传统比例导引上增加两项偏置项,推导出一种新型攻击时间和角度控制的导引律,并用Lyapunov理论证明其稳定性。针对导弹大机动下视场角可能超过导引头视场角范围而丢失目标的问题,将用于角度控制的偏置项分为三个阶段,设计了导引头视场角限制下的导引过程。仿真结果表明:所设计的导引律可以将视场角限制在导引头视场角范围内,实现不同位置下的多枚导弹以指定角度同一时间攻击目标,达到导弹协同攻击的效果。 展开更多
关键词 视场角 攻击时间 攻击角度 导引律 协同攻击
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CT图像重建视野大小对放射治疗计划剂量计算及体积评估的影响 被引量:2
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作者 陆中杰 严森祥 +1 位作者 卜路懿 周进淇 《中华放射医学与防护杂志》 CAS CSCD 北大核心 2010年第3期303-306,共4页
目的 探讨CT图像重建视野(FOV)大小对放射治疗计划剂量计算及体积评估可能存在的影响.方法 对16例鼻咽癌患者的CT原始扫描数据分别行45 cm常规FOV和65 cm扩展视野(EFOV)重建并传输至放射治疗计划系统,所有病例均在常规FOV重建的CT... 目的 探讨CT图像重建视野(FOV)大小对放射治疗计划剂量计算及体积评估可能存在的影响.方法 对16例鼻咽癌患者的CT原始扫描数据分别行45 cm常规FOV和65 cm扩展视野(EFOV)重建并传输至放射治疗计划系统,所有病例均在常规FOV重建的CT图像上勾画肿瘤体积(GTV)、临床靶区(CTV)及脑干、晶体、腮腺、脊髓等危及器官,并制定7野等角动态调强放射治疗计划(GTV处方剂量70 Gy).两种重建方法图像按照医学数字影像通信3.0标准(DICOM 3.0)坐标方式融合后,拷贝常规FOV图像上的靶区及危及器官至EFOV图像,并将治疗计划移植至EFOV图像,治疗计划中心为两种重建方法图像的同一DICOM坐标,利用剂量体积直方图(DVH)工具计算两种重建方法图像上GTV、CTV和脑干、晶体、腮腺、脊髓的体积、最大剂量(Dmax)、平均剂量(Dmean)及最小剂量(Dmin).将入组病例的每个治疗计划7野分别导入常规45 cm FOV和65 cmEFOV重建的二维通量图验证设备Mapchek 1175的模体,距离通过协议(DTA)分析5 cm深度平面绝对剂量的计算和实测结果通过率.结果 两种重建方法图像上的靶区和危及器官的体积差异具有统计学意义,所有入组病例靶区和危及器官在常规FOV图像上的体积均大于EFOV图像上的体积.较小体积的晶体最大剂量Dmax常规FOV与EFOV图像之间差异有统计学意义(t=-3.14,P〈0.007),其余靶区及危及器官的最大剂量Dmax差异无统计学意义.CTV和GTV平均剂量Dmean在EFOV图像上大于FOV图像,差异有统计学意义(t=-6.45、-5.65,P〈0.001),危及器官的平均剂量Dmean和靶区及危及器官最小剂量Dmin差异均无统计学意义.两种重建方法图像上治疗计划的7野通过率之间差异无统计学意义.结论 在放射治疗CT模拟定位过程中图像重建FOV的大小对于靶区及部分危及器官的体积及剂量计算结果和治疗计划的评价存在影响;� 展开更多
关键词 CT 鼻咽癌 视野 剂量 放射治疗
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