Sequential quadratic programming-based non-cooperative target distributed hybrid processing optimization method

The distributed hybrid processing optimization problem of non-cooperative targets is an important research direction for future networked air-defense and anti-missile firepower systems. In this paper, the air-defense anti-missile targets defense problem is abstracted as a nonconvex constrained combinatorial optimization problem with the optimization objective of maximizing the degree of contribution of the processing scheme to non-cooperative targets, and the constraints mainly consider geographical conditions and anti-missile equipment resources. The grid discretization concept is used to partition the defense area into network nodes, and the overall defense strategy scheme is described as a nonlinear programming problem to solve the minimum defense cost within the maximum defense capability of the defense system network. In the solution of the minimum defense cost problem, the processing scheme, equipment coverage capability, constraints and node cost requirements are characterized, then a nonlinear mathematical model of the non-cooperative target distributed hybrid processing optimization problem is established, and a local optimal solution based on the sequential quadratic programming algorithm is constructed, and the optimal firepower processing scheme is given by using the sequential quadratic programming method containing non-convex quadratic equations and inequality constraints. Finally, the effectiveness of the proposed method is verified by simulation examples.

Impedance control of multi-arm space robot for the capture of non-cooperative targets

Robotic systems are expected to play an increasingly important role in future space activities. The robotic on-orbital service, whose key is the capturing technology, becomes a research hot spot in recent years. This paper studies the dynamics modeling and impedance control of a multi-arm free-flying space robotic system capturing a non-cooperative target. Firstly, a control-oriented dynamics model is essential in control algorithm design and code realization. Unlike a numerical algorithm, an analytical approach is suggested. Using a general and a quasi-coordinate Lagrangian formulation, the kinematics and dynamics equations are derived.Then, an impedance control algorithm is developed which allows coordinated control of the multiple manipulators to capture a target.Through enforcing a reference impedance, end-effectors behave like a mass-damper-spring system fixed in inertial space in reaction to any contact force between the capture hands and the target. Meanwhile, the position and the attitude of the base are maintained stably by using gas jet thrusters to work against the manipulators' reaction. Finally, a simulation by using a space robot with two manipulators and a free-floating non-cooperative target is illustrated to verify the effectiveness of the proposed method.

Design of a Non-cooperative Target Capture Mechanism

A passive compliant non-cooperative target capture mechanism is designed to maintain the non-cooperative target on-orbit. When the relative position between capture mechanism and satellite is confirmed,a pair of four-bar linkages lock the docking ring,which is used for connecting the satellite and the rocket. The mathematical model of capture mechanism and capture space is built by the Denavit-Hartenberg(D-H)method,and the torque of each joint is analyzed by the Lagrange dynamic equation. Besides,the capture condition and the torque of every joint under different capture conditions are analyzed by simulation in MSC. Adams. The results indicate that the mechanism can capture the non-cooperative target satellite in a wide range. During the process of capture,the passive compliant mechanism at the bottom can increase capture space,thereby reducing the difficulty and enhance stability of the capture.

Design of a Flexible Capture Mechanism Inspired by Sea Anemone for Non-cooperative Targets

Robotic grippers have been used in industry as end-effectors but are usually limited to operations in pre-defined workspace.However,few devices can capture irregularly shaped dynamic targets in space,underwater and other unstructured environments.In this paper,a novel continuum arm group mechanism inspired by the morphology and motions of sea anemones is proposed.It is able to dissipate and absorb the kinetic energy of a fast moving target in omni-direction and utilize multiple arms to wrap and lock the target without accurate positioning control.Wire-driven actuation systems are implemented in the individual continuum arms,achieving both bending motion and stiffness regulation.Through finite element method,the influence of different configurations of the continuum arm group on the capture performance is analyzed.A robotic prototype is constructed and tested,showing the presented arm group mechanism has high adaptability to capture targets with different sizes,shapes,and incident angles.

Simulation of the RCS Range Resolution of Extremely Large Target

The high frequency hybrid technique based on an iterative Physical Optics(PC)) and the method of equivalent current (MEC) approach is developed for predicting rangeresolution of the Radar Cross Section (RCS) in the spatial domain. We introduce the hybrid highfrequency method to simulate range resolution of the extremely large target in the near zone. Thispaper applies this method to simulate the range resolution of the two 1 m X 1 m plates and the ship.The study improves the speed of simulatingthe range resolution of the extremely large target and isprepared for the application of the extrapolation and interpolation in the spatial domain.

Non-cooperative target pose estimation based on improved iterative closest point algorithm

For localisation of unknown non-cooperative targets in space,the existence of interference points causes inaccuracy of pose estimation while utilizing point cloud registration.To address this issue,this paper proposes a new iterative closest point(ICP)algorithm combined with distributed weights to intensify the dependability and robustness of the non-cooperative target localisation.As interference points in space have not yet been extensively studied,we classify them into two broad categories,far interference points and near interference points.For the former,the statistical outlier elimination algorithm is employed.For the latter,the Gaussian distributed weights,simultaneously valuing with the variation of the Euclidean distance from each point to the centroid,are commingled to the traditional ICP algorithm.In each iteration,the weight matrix W in connection with the overall localisation is obtained,and the singular value decomposition is adopted to accomplish high-precision estimation of the target pose.Finally,the experiments are implemented by shooting the satellite model and setting the position of interference points.The outcomes suggest that the proposed algorithm can effectively suppress interference points and enhance the accuracy of non-cooperative target pose estimation.When the interference point number reaches about 700,the average error of angle is superior to 0.88°.

Identifying the sensitive areas in targeted observation for predicting the Kuroshio large meander path in a regional ocean model

With the Regional Ocean Modeling System(ROMS),this paper investigates the sensitive areas in targeted observation for predicting the Kuroshio large meander(LM)path using the conditional nonlinear optimal perturbation approach.To identify the sensitive areas,the optimal initial errors(OIEs)featuring the largest nonlinear evolution in the LM prediction are first calculated;the resulting OIEs are localized mainly in the upper 2500 m over the LM upstream region,and their spatial structure has certain similarities with that of the optimal triggering perturbation.Based on this spatial structure,the sensitive areas are successfully identified,located southeast of Kyushu in the region(29°–32°N,131°–134°E).A series of sensitivity experiments indicate that both the positions and the spatial structure of initial errors have important effects on the LM prediction,verifying the validity of the sensitive areas.Then,the effect of targeted observation in the sensitive areas is evaluated through observing system simulation experiments.When targeted observation is implemented in the identified sensitive areas,the prediction errors are effectively reduced,and the prediction skill of the LM event is improved significantly.This provides scientific guidance for ocean observations related to enhancing the prediction skill of the LM event.

Calibration of Camera with Large Field-of-View Based on Flexible Planar Target

For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.

A Method to Obtain the Moving Speed of Uncooperative Target Based on Only Two Measurements

The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This article proposes a new method that requires only two consecutive measurements. While using the azimuth measurement to obtain the angular difference between two radial distances, it also conducts two consecutive Doppler frequency shift measurements at the same target azimuth. On the basis of this measurement, a frequency difference equation is first constructed and solved jointly with the Doppler frequency shift equation. By eliminating the velocity variable and using the measured angular difference to obtain the target’s lead angle, the target’s velocity can be solved by using the Doppler frequency shift equation again. The new method avoids the condition that the target must move equidistantly, which not only provides an achievable method for engineering applications but also lays a good foundation for further exploring the use of steady-state signals to achieve passive positioning.

An innovative inertial parameters identification method for non-cooperative space targets based on electrostatic interaction

Inertial characteristics of non-cooperative targets are crucial for space capture and sub-sequent on-orbit servicing.Previous methods for identifying inertial parameters involve proximity operations,which are associated with the risk of collision with non-cooperative targets.This paper introduces a long-range,contactless method for identifying the inertial parameters of a non-cooperative target during the pre-capture phase.Specifically,electrostatic interaction is used as an external excitation to alter the target's motion.A force estimation algorithm that uses measure-ments from visual and potential sensors is proposed to estimate the electrostatic interaction and eliminate the need for force sensors.Furthermore,a recursive estimation-identification framework is presented to concurrently estimate the coupled motion state,weak electrostatic interaction,and inertial parameters of the target.The simulation results show that the proposed method extends the identification distance to 170 times that of the previous method while maintaining high identifica-tion precision forall parameters.

Analytic optimal pose tracking control in close-range proximity operations with a non-cooperative target

This paper investigates an analytical optimal pose tracking control problem for chaser spacecraft during the close-range proximity operations with a non-cooperative space target subject to attitude tumbling and unknown orbital maneuvering.Firstly,the relative translational motion between the orbital target and the chaser spacecraft is described in the Line-of-Sight(LOS)coordinate frame along with attitude quaternion dynamics.Then,based on the coupled 6-Degree of Freedom(DOF)pose dynamic model,an analytical optimal control action consisting of constrained optimal control value,application time and its duration are proposed via exploring the iterative sequential action control algorithm.Meanwhile,the global closed-loop asymptotic stability of the proposed predictive control action is presented and discussed.Compared with traditional proximity control schemes,the highlighting advantages are that the application time and duration of the devised controller is applied discretely in light of the influence of the instantaneous pose configuration on the pose tracking performance with less energy consumptions rather than at each sample time.Finally,three groups of illustrative examples are organized to validate the effectiveness of the proposed analytical optimal pose tracking control scheme.

Nine-year clinical outcomes of drug-eluting stents vs. bare metal stents for large coronary vessel lesions

Objectives To evaluate the very long-term safety and effectiveness of drug-eluting stents （DES） compared to bare-metal stents （BMS） for patients with large coronary vessels. Methods From April 2004 to October 2006, 2407 consecutive patients undergoing de novo lesion percutaneous coronary intervention with reference vessel diameter greater than or equal to 3.5 mm at Fu Wai Hospital in Beijing, China, were prospectively enrolled into this study. We obtained 9-year clinical outcomes including death, myocardial infarction （MI）, thrombosis, target lesion revascularization （TLR）, target vessel revascularization （TVR）, and major adverse cardiac events （MACE, the composite of death, MI, and TVR）. We performed Cox＇s proportional-hazards models to assess relative risks of all the outcome measures after propensity match. Results After propensity scoring, 514 DES-treated patients were matched to 514 BMS-treated patients. The patients treated with BMS were associated with higher risk ofTLR （HR： 2.55, 95%CI： 1.520-4.277, P = 0.0004） and TVR （HR： 1.889, 95%CI： 1.185-3.011, P = 0.0075）, but the rates of death/MI and MACE were not statistically different. All Academic Research Consortium definition stent thrombosis at 9-year were comparable in the two groups. Conclusions During long-term follow-up through nine years, use of DES in patients with large coronary arteries was still associated with significant reductions in the risks of TLR and TVR.

Evaluation of a five-gene signature associated with stromal infiltration for diffuse large B-cell lymphoma

BACKGROUND Diffuse large B-cell lymphoma(DLBCL)is a common non-Hodgkin lymphoma.The development of immunotherapy greatly improves the patient prognosis but there are some exceptions.Thus,screening for better biomarkers for prognostic evaluation could contribute to the treatment of DLBCL patients.AIM To screen the novel mediators involved in the development of DLBCL.METHODS The GSE60 dataset was applied to identify the differentially expressed genes(DEGs)in DLBCL,and the principal components analysis plot was used to determine the quality of the included samples.The protein-protein interactions were analyzed by the STRING tool.The key hub genes were entered into to the GEPIA database to determine their expressions in DLBCL.Furthermore,these hub gene alterations were analyzed in cBioportal.The UALCAN portal was employed to analyze the expression of the hub genes in different stages of DLBCL.The Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data Score was conducted to evaluate the correlation between the gene expression and tumor purity.The gene-gene correlation analysis was conducted in the GEPIA.The stromal score analysis was conducted in TIMER to confirm the correlation between the gene expression and infiltrated stromal cells.The correlation between the indicated genes and infiltration level of cancerassociated fibroblasts(CAFs)was also completed in TIMER with two methods,MCP-Counter and Tumor immune dysfunction and exclusion.The correlation between fibronectin(FN1)protein level and secreted protein acidic and cysteinerich(SPARC)messenger ribonucleic acid expression was confirmed in the cBioportal.RESULTS The top 20 DEGs in DLBCL were identified,and the principal components analysis plot confirmed the quality of the significant DEGs.The pairwise correlation coefficient analysis among all samples showed that these DEGs have a certain co-expression pattern.The DEGs were subjected to STRING to identify the hub genes,alpha-2-macroglobulin(A2M),cathepsin B(CTSB),FN1,matrix metallopeptidase 9(MMP9),and SPARC.The five hub genes were confirmed to be overexpressed in DLBCL.The cBioportal portal detected these five hub genes that had gene alteration,including messenger ribonucleic acid high amplification and missense mutation,and the gene alteration percentages of A2M,FN1,CTSB,MMP9,and SPARC were 5%,8%,5%,2.7%,and 5%,respectively.Furthermore,the five hub genes had a potential positive correlation with tumor stage.The correlation analysis between the five genes and tumor purity confirmed that the five genes were overexpressed in DLBCL and had a positive correlation with the development of DLBCL.More interestingly,the five genes had a significant correlation with the stromal infiltration scores.The correlation analysis between the fives genes and CAFs also showed a significant value,among which the top two genes,FN1 and SPARC,had a remarkable co-expression pattern.CONCLUSION The top DEGs were identified,and the five hub genes were overexpressed in DLBCL.Furthermore,the gene alterations were confirmed and the positive correlation with tumor purity revealed the overexpression of the five genes and close association with the development of DLBCL.More interestingly,the five genes were positively correlated with stromal infiltration,especially in CAFs.The top two genes,FN1 and SPARC,showed a co-expression pattern,which indicates their potential as novel therapeutic targets for DLBCL.

一种应用于大尺寸测量系统的坐标系自动标定方法

针对现有方法在标定过程中过于繁琐的问题,提出了一种应用于大尺寸测量系统的坐标系全自动标定方法。该方法通过固定两个在测量单元局部坐标系已知坐标的测量节点作为标记靶,测量单元之间相互测量彼此的标记靶获得标记靶上的测量点在不同坐标系下的坐标值,利用这些坐标值建立三维几何约束,从而自动标定不同坐标系之间的坐标转换关系。借助于精密激光定位系统平台进行实验验证,结果表明,所提方法可以实现测量单元局部坐标系之间的自动标定,降低了坐标系标定过程中的人工成本。在距离测量单元布站区域约2 m,大小为5 000 mm×5 000 mm×500 mm的测量空间中长度测量的精度在0.46 mm/m以内,测试点三维坐标测量的标准偏差在0.026 mm以内,可以满足绝大部分工业测量的需求。该方法极大的提高了系统的标定效率,有望为具有自动标定功能的大尺寸测量设备的产品化提供新的理论基础。

弥漫大B细胞淋巴瘤中ERK和p38的表达及临床病理学意义

目的探讨ERK和p38在弥漫大B细胞淋巴瘤(DLBCL)中的表达与各临床病理指标之间的关系,及其与预后的相关性。方法运用免疫组化检测152例弥漫大B细胞淋巴瘤中ERK和p38阳性表达情况,应用SPSS 23.0软件分析其与各临床病理指标的关系。结果在DLBCL中,ERK、p38的阳性率分别为68.4%、50%,ERK、p38在肿瘤直径>4 cm中阳性表达率高,差异均有统计学意义,且均与肿瘤直径显著正相关。p38在结内病变和结外侵犯>2个淋巴结阳性表达率更高,差异有统计学意义,且与结外侵犯正相关,与原发部位负相关。多因素分析中,表现状态评分、LDH水平和R-CHOP治疗是影响DLBCL患者总生存期的独立危险因素。结论这些发现表明ERK和p38在DLBCL中的致癌作用,提示它们是DLBCL潜在的治疗靶点。

基于稀疏重构的空域大目标背景下的小目标检测方法

现代战争经常需要大小平台协同作战,较为典型的是有/无人编队协同作战。在协同作战过程中,由于大目标的回波副瓣掩盖了小目标回波,导致无法实现大小目标一体化检测,给指挥员战场态势的判断带来了严峻的挑战。为此研究了一种基于稀疏重构的空域大目标背景下的小目标检测方法,利用压缩感知稀疏重构算法的高分辨特性实现大小目标在空域上分离,进而消除大目标对小目标的检测影响。针对传统稀疏重构方法存在重构准确率与计算效率相互矛盾的问题,提出了一种基于虚变换的稀疏重构方法。仿真分析结果表明,所提方法相对于传统正交投影(Orthogonal Matching Projection,OMP)方法具有更好的大小目标分离准确度,而相对于传统凸优化重构方法,可以实现计算效率提升16%。

改进YOLOv7的小目标检测算法研究

随着深度学习在国内目标检测的不断应用,常规的大、中目标检测已经取得惊人的进步,但由于卷积网络本身的局限性,针对小目标检测依然会出现漏检、误检的问题,以数据集Visdrone2019和数据集FloW-Img为例,对YOLOv7模型进行研究,在网络结构上对骨干网的ELAN模块进行改进,将Focal NeXt block加入到ELAN模块的长短梯度路径中融合来强化输出小目标的特征质量和提高输出特征包含的上下文信息含量,在头部网络引入RepLKDeXt模块,该模块不仅可以取代SPPCSPC模块来简化模型整体结构还可以利用多通道、大卷积核和Cat操作来优化ELAN-H结构,最后引入SIOU损失函数取代CIOU函数以此提高该模型的鲁棒性。结果表明改进后的YOLOv7模型参数量减少计算复杂性降低并在小目标密度高的Visdrone 2019数据集上的检测性能近似不变,在小目标稀疏的FloW-Img数据集上涨幅9.05个百分点,进一步简化了模型并增加了模型的适用范围。

一种联合TDCM和PFA的空间目标大转角ISAR成像方法

空间目标态势感知是当前航天技术领域的研究热点,逆合成孔径雷达(Inverse Synthetic Aperture Radar, ISAR)是空间目标感知的一种有效手段。为了得到利于目标鉴别的高分辨二维ISAR图像,需要通过增大积累转角来提高方位向分辨率。但是,随着转角的增大,平动与转动之间的耦合增大,使得传统的先平动补偿、后利用转动成像的两步式成像方法不再适用。本文提出了一种结合时域信号共轭相乘(Time Domain Conjugate Multiplication, TDCM)处理与极坐标格式算法(Polar Format Algorithm, PFA)的成像算法,首先利用雷达回波的二维相干性,通过TDCM处理进行平动粗补偿,然后借助PFA的插值操作校正大转角引起的散射点越分辨单元走动(Motion Through Resolution Cell, MTRC)并估计目标相对转动参数。通过迭代处理,持续对平动和转动参数进行优化,提升运动补偿效果。仿真验证了所提成像算法的有效性,与传统算法相比,成像聚焦性更好。

基于人工蜂群算法的大规模武器目标分配研究

针对大规模武器目标分配问题,本文提出一种改进的多目标武器目标分配模型,该模型将武器平台泛化为武器,并将武器平均飞行时间作为第2个优化目标。为有效解决这类问题,本文还提出了改进的自适应离散多目标人工蜂群算法。该算法基于人工蜂群算法和非支配排序策略,引入了自适应算子操作数、重用蜜源探索信息的变异概率策略,并通过蜜源之间、蜜源与外部解集之间的交互以提高算法的收敛性,通过算子的随机选择保持种群多样性。最后通过不同规模武器目标分配的对比实验,证明了所提自适应算子操作数与重用蜜源探索次数的变异概率策略的有效性,并与MOABC、MOPSO、NSGA-II算法在反向世代距离、超体积、时间3个方面进行比较,本文算法能够在保证时效性的前提下得到质量更好的Pareto解集。

面向大规模目标跟踪的相控阵雷达资源分配方法

相比于传统雷达,相控阵雷达能够同时生成多个波束并灵活改变波束指向,被广泛应用于多目标跟踪领域。在大规模集群目标协同探测场景中,为支持后续节点对敌方目标进行火力拦截与打击的任务需求,相控阵雷达需要在规定时间内将空域内优先级更高的目标更快地跟踪至火控精度,然而若空域内目标数量过多,雷达探测资源有限,难以完成指定跟踪任务。为了解决这一问题,本文提出了一种面向大规模目标跟踪的相控阵雷达目标分配与功率联合优化算法。首先,推导出包含目标分配和功率优化的预测条件克拉美罗下界,并将其作为目标跟踪性能的衡量指标;随后,本文同时考虑跟踪容量和跟踪精度,以最大化满足跟踪精度的目标数量和最小化多目标优先级加权平均跟踪误差为优化目标,结合相控阵雷达系统资源,建立了大规模目标跟踪下的目标分配和功率联合优化模型,对目标分配变量和发射功率变量进行自适应联合优化配置。针对上述优化问题,本文采用两步分解法,将其分解为目标分配子问题和功率优化子问题,并结合激活函数对非平滑非凸的目标函数进行平滑近似。然后,利用谱投影梯度法进行求解。仿真实验验证了所提算法相较于传统算法在多个场景下均能在指定时间内更快速地将更多目标跟踪至指定精度。