Improvedforward—lookingimagingmethodforairbornearrayFMCWSAR

机载阵列前视合成孔径雷达（SAR）信号模型中忽略载机速度会影响成像。针对该问题，在调频连续波（FMCW）SAR信号模型中考虑了载机速度，分析了栽机速度的影响和裁机连续运动引入的多普勒频率偏移的特点，结合FrequencyScaling算法，研究了机载阵列FMCWSAR前视成像。成像仿真和性能参数分析表明：改进方法可精确实现载机运动条件下的FMCWSAR前视成像。

基于多Agent强化学习的多站点CSPS系统的协作Look-ahead控制

研究多站点传送带给料生产加工站(Conveyor-serviced production station,CSPS)系统的最优控制问题,其优化目标是通过合理选择每个CSPS的Look-ahead控制策略,实现整个系统的工件处理率最大.本文首先根据多Agent系统的反应扩散思想,对每个Agent的原始性能函数进行改进,引入了具有扩散功能的局域信息交互项(原始项看作具有反应功能);并运用性能势理论,构建一种适用于平均和折扣两种性能准则的Wolf-PHC多Agent学习算法,以求解决策时刻不同步的多站点的协作Look-ahead控制策略.最后,论文通过仿真实验验证了该算法的有效性,学习结果表明,通过性能函数的改进,各工作站的负载平衡性得到改善,整个系统的工件处理率也明显提高.

结合look-ahead值排序的自适应分支求解算法

基于新近提出的自适应分支约束求解框架,结合look-ahead值启发式,提出一种新的约束求解算法AdaptBranchLVO。为验证算法效率,在标准测试库上进行了充分对比实验。结果表明,新提出算法在效率上明显优于已有的自适应分支求解算法。

完备格子气自动机Look－UPTable的状态

给出了完备格子气模型的Ｌｏｏｋ－ＵｐＴａｂｌｅ的状态解的存在条件，并给出特定情况下的状态个数．

格子气自动机Look-Up表的简并度

给出格子气自动机中具有三条守恒律的

VLOOKUP函数的初级用法

Excel应用中,VLOOKUP函数是查找数据神器。在EXCEL数据表里查找数据时,如果数据表的面积非常大,可以通过VLOOKUP函数来快速查找数据。VLOOKUP函数是EXCEL软件中特别重要的一个函数。我们从理解VLOOKUP函数入手,结合实例给出具体应用及操作步骤。用好VLOOKUP函数可以大幅提高查找数据的工作效率。

CNC中基于Bezier拟合的Look-Ahead轨迹规划的研究

轨迹规划是CNC系统的重要功能之一。传统CNC在处理连续微小NC程序时,存在诸如机床震颤、工件毛刺、加工效率低等问题。作者提出的Look-Ahead轨迹规划算法能解决上述问题,此算法将NC程序分成3种"大路径段",将连续微小路径(CSBs)拟合成Bezier曲线,再进行速度规划和轨迹插补,在此基础上提出Look-Ahead离线插补器的结构。仿真结果表明,该算法能够实现大量微小路径的连续加工。

基于修正ANT逻辑高速树形32 BitCarry Lookahead加法器

一种用修正全NMOS管逻辑(ANT)实现的树形结构高速32bitcarryLookahead加法器,使用两相时钟动态CMOS逻辑、修正不反向ANT逻辑和二进制树形结构实现。该加法器运用0.25μm工艺,文中给出了修正ANT逻辑中所有晶体管的宽长尺寸和仿真结果,最高工作频率为2GHz,计算结果在3.5个时钟周期后有效。

Second-look endoscopy with prophylactic hemostasis is still effective after endoscopic submucosal dissection for gastric neoplasm

AIM: The clinical value of second-look endoscopy(SLE) after endoscopic submucosal dissection(ESD) has been doubted continuously. The aim of this study was to assess the effectiveness of SLE based on the risk of delayed bleeding after ESD. METHODS: A total of 310 lesions of gastric epithelial neoplasms treated by ESD were reviewed. The lesions were divided into two groups based on the risk of postprocedural bleeding estimated by Forrest classification. The high risk of rebleeding group(Forrest?Ⅰa,?Ⅰb and Ⅱa) required endoscopic treatment, while the low risk of rebleeding group(Forrest Ⅱb, Ⅱc and Ⅲ) did not. Delayed bleeding after ESD was investigated. RESULTS: Sixty-six lesions were included in the high risk of rebleeding group and 244 lesions in the low risk of rebleeding group. There were no significant differences in delayed bleeding between the high risk group(1/66) and the low risk group(1/244)(P = 0.38). The high risk of rebleeding group tended to be located more often in the mid-third and had higher appearance of flat or depressed shape than the low risk group(P = 0.004 and P = 0.006, respectively). CONCLUSION: SLE with pre-emptive prophylactic endoscopic treatment is still effective in preventing delayed bleeding after ESD.

A Generalized Acceleration and Deceleration Approach for Continuous Small Line Blocks with Look-ahead

Generally complex 3D contours are divided into a lot of continuous small line blocks by CAD/CAM software. When these small line blocks are used in conventional way,machine tool has to stop at the end of one move before continuing on to the next to meet accuracy requirement,which results in inefficiency.Look-ahead is an intelligent function that aims at adjusting the feed rate automatically to achieve maximum productivity while maintaining accuracy.By now most researchers just utilize the simplest linear acceleration(ACC)and deceleration(DEC)to deal with look-ahead intelligence.A generalized ACC/DEC ap- proach and corresponding optimal look-ahead algorithm based on dynamic back tracking along a doubly linked list are proposed.An improved rounding strategy for reducing interpolation errors is also presented.By using the proposed techniques,arbitrary velocity profiles that offer look-ahead feature and have the desired ACC/DEC characteristics for movement of a lot of continuous line blocks can be generated efficiently.Both simulations and experiments showed the productivity was dramatically increased without sacri- fice of accuracy.

A general purpose exact Rayleigh scattering look-up table for ocean color remote sensing

The current exact Rayleigh scattering calculation of ocean color remote sensing uses the look-up table （LUT）, which is usually created for a special remote sensor and cannot be applied to other sensors. For practical application, a general purpose Rayleigh scattering LUT which can be applied to all ocean color remote sensors is generated. An adding-doubling method to solve the vector radiative transfer equation in the plane-parallel atmosphere is deduced in detail. Compared with the exact Rayleigh scattering radiance derived from the MODIS exact Rayleigh scattering LUT, it is proved that the relative error of Rayleigh scattering calculation with the adding-doubling method is less than 0.25%, which meets the required accuracy of the atmospheric correction of ocean color remote sensing. Therefore, the adding-doubling method can be used to generate the exact Rayleigh scattering LUT for the ocean color remote sensors. Finally, the general purpose exact Rayleigh scattering LUT is generated using the adding-doubling method. On the basis of the general purpose LUT, the calculated Rayleigh scattering radiance is tested by comparing with the LUTs ofMODIS, SeaWiFS and the other ocean color sensors, showing that the relative errors are all less than 0.5%, and this general purpose LUT can be applied to all ocean color remote sensors.

Look-Locker和B1修正变量翻转角技术在正常乳腺组织T_1值测量中的对照研究

目的:比较分析Look-Locker和B1修正变量翻转角(B1-corrected VFA)成像技术获得的正常乳腺腺体及胸壁肌肉的T1弛豫时间。方法:对77例正常乳房分别行Look-Locker和B1-corrected VFA序列扫描获得T1-mapping图像,由两位医师分别测量乳房腺体、胸壁肌肉的T1值,采用组内相关系数(ICC)对两位医师的测量结果进行一致性分析,并分析两种成像方法的变异度,比较两种成像方法的组织T1值差异。结果:两位医师之间乳腺腺体、胸壁肌肉的look-locker法获得T1值的ICC值分别为0.883、0.818;两位医师之间乳腺腺体、胸壁肌肉B1-corrected VFA法获得T1值的ICC值分别为0.796、0.757,一致性均为非常好。Look-Locker法与B1-corrected VFA法所得两种组织的T1值差异均有统计学意义[腺体组织T1值分别为(1423.42±80.63)和(2042.09±150.18)ms,t=35.14,P<0.05;肌肉组织T1值分别为(1369.79±65.24)和(2044.84±133.07)ms,t=48.53,P<0.05]。腺体组织Look-Locker法和B1-corrected VFA法获得的T1值的变异度分别为0.057和0.074,胸壁肌肉组织两种方法获得的T1值的变异度分别为0.048和0.065。结论:采用Look-Locker和B1-corrected VFA法获取正常乳房结构的T1值可行,可重复性较好;两种方法测量的T1值差异有统计学意义,但各组织的变异度较小,能反映正常乳房腺体、肌肉组织的特性,有可能为临床的进一步研究提供基础。

Second-look surgery plus hyperthermic intraperitoneal chemotherapy for patients with colorectal cancer at high risk of peritoneal carcinomatosis:Does it really save lives?

The treatment of peritoneal carcinomatosis (PC) of colorectal origin with cytoreductive surgery(CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) has a 5-year recurrence-free or cure rate of at least 16%, so it is no longer labeled as a fatal disease, and offers prolonged survival for patients with a low peritoneal carcinomatosis index. Metachronous PC of colorectal origin is so predictable that there is a model which has been used to successfully determine the individual risk of each patient. Patients at risk are clearly identified; those with the highest risk have small peritoneal nodules present in the first surgery (70% probability of developing PC), ovarian metastases(60%), perforated tumor onset or intraoperative tumor rupture(50%). Current clinical, biological and imaging techniques still lack sufficient sensitivity to diagnose PC in its initial stages, when CRS plus HIPEC has a greater impact and a higher cure rate. Second-look surgery with HIPEC or prophylactic HIPEC at the time of the first intervention have been proposed as means of preventing and/or anticipating clinical or radiological relapse in at-risk patients. Both techniques have shown a significant decrease in peritoneal relapses and should be considered essential weapons in the management of colorectal cancer.

基于You Only Look Once v2优化算法的车辆实时检测

针对基于You Only Look Once v2算法的目标检测存在精度低及稳健性差的问题,提出一种车辆目标实时检测的You Only Look Once v2优化算法;该算法以You Only Look Once v2算法为基础,通过增加网络深度,增强特征提取能力,同时,通过添加残差模块,解决网络深度增加带来的梯度消失或弥散问题;该方法将网络结构中低层特征与高层特征进行融合,提升对小目标车辆的检测精度。结果表明,通过在KITTI数据集上进行测试,优化后的算法在检测速度不变的情况下,提高了车辆目标检测精度,平均精度达到0.94,同时提升了小目标检测的准确性。

LOOK-AHEAD ALGORITHM FOR VELOCITY CONTROL BASED ON PARAMETERIZED CURVE INTERPOLATOR

To avoid suffering gouge and transient overshooting in high speed cutting machining, a novel parametefized curve interpolator model with velocity look-ahead algorithm is proposed. Based on a prearrangement step interpolation algorithm for parameterized curves and considering high curvature points, parameterized curve tool path is divided into acceleration segments and deceleration segments by look-ahead algorithm. Under condition of characteristics of acceleration and deceleration stored in control system, deceleration before high curvature points and acceleration after high curvature points are realized in real-time in high speed cutting machining. Based on new parameterized curve interpolator model with velocity look-ahead algorithm, a real cubic spline is machined simulativly. The simulation results show that velocity look-ahead algorithm improves velocity changing more smoothly.

RESEARCH ON THE BISTATIC FORWARD-LOOKING SAR IMAGING

The bistatic Synthetic Aperture Radar (SAR) systems with separate transmitter and receiver antennas provide a new potential to imaging in the forward-looking geometry. Analysis of the Doppler property in this paper indicates the feasibility of Bistatic Forward-Looking (BFL) SAR imaging. Considering the different Doppler property determined by the two platforms in BFL SAR, a new 2-D point target spectrum is derived in our study. Based on the spectrum, an imaging method is chosen for the configuration, and the point target simulation validates the analysis.

Nonlinear RCMC method for spaceborne/airborne forward-looking bistatic SAR

In the spaceborne/airborne forward-looking bistatic syn- thetic aperture radar （SA-FBSAR）, due to the system platforms＇ remarkable velocity difference and the forward-looking mode, the range cell migration （RCM） not only depends on the target＇s two- dimensional location, but also varies with the range location non- linearly. And the nonlinearity is not just the slight deviation from the linear part, but exhibits evident nonlinear departure in the RCM trajectory. If the RCM is not properly corrected, nonlinear image distortions would occur. Based on the RCM model, a modified two-step RCM compensation （RCMC） method for SA-FBSAR is proposed. In this method, firstly the azimuth-dependent RCM is compensated by the scaling Fourier transform and the phase multi- plication. And then the range-dependent RCM is removed through interpolation. The effectiveness of the proposed RCMC method is verified by the simulation results of both point scatterers and area targets.

STUDY ON SPECKLE REDUCTION IN MULTI-LOOK POLARIMETRIC SAR IMAGE

This paper studies the speckle reduction in multi-look polarimetric synthetic aperture radar (SAR) image. A multi-look polarimetric whitening filtering (MPWF) method is presented and extended to form a fully polarimetric filter with multi-channel output. The paper also quantifies the speckle reduction amount achievable by the MPWF, and compares the MPWF with the span, weighting and power equalization methods. Experimental results with the NASA/JPL L-band 4-look polarimetric SAR data verify the effectiveness and superiority of the MPWF, and show that the MPWF is of great advantage for enhancing SAR image classification.

High-resolution forward-looking imaging algorithm for missile-borne detectors

Aiming at a novel missile-borne detector in the optional burst height proximity fuze, a self-adaptive high-resolution forward-looking imaging algorithm (SAHRFL-IA) is presented. The echo data are captured by the missile-borne detector in the target regions;thereby the azimuth angulation accuracy at the same distance dimension is improved dynamically. Thus, azimuth information of the targets in the detection area may be obtained accurately. The proposed imaging algorithm breaks through the conventional misconception of merely using azimuth discrimination curves under ideal conditions during monopulse angulation. The real-time echo data from the target region are used to perform error correction for this discrimination curve, and finally the accuracy of the azimuth angulation may reach the optimum at the same distance dimension. A series of experiments demonstrate the validity, reliability and high performance of the proposed imaging algorithm. Azimuth angulation accuracy may reach ten times that of the detection beam width. Meanwhile, the running time of this algorithm satisfies the requirements of missile-borne platforms.