Target Controllability of Multi-Layer Networks With High-Dimensional Nodes

This paper studies the target controllability of multilayer complex networked systems,in which the nodes are highdimensional linear time invariant(LTI)dynamical systems,and the network topology is directed and weighted.The influence of inter-layer couplings on the target controllability of multi-layer networks is discussed.It is found that even if there exists a layer which is not target controllable,the entire multi-layer network can still be target controllable due to the inter-layer couplings.For the multi-layer networks with general structure,a necessary and sufficient condition for target controllability is given by establishing the relationship between uncontrollable subspace and output matrix.By the derived condition,it can be found that the system may be target controllable even if it is not state controllable.On this basis,two corollaries are derived,which clarify the relationship between target controllability,state controllability and output controllability.For the multi-layer networks where the inter-layer couplings are directed chains and directed stars,sufficient conditions for target controllability of networked systems are given,respectively.These conditions are easier to verify than the classic criterion.

Target layer state estimation in multi-layer complex dynamical networks considering nonlinear node dynamics

In many engineering networks, only a part of target state variables are required to be estimated.On the other hand,multi-layer complex network exists widely in practical situations.In this paper, the state estimation of target state variables in multi-layer complex dynamical networks with nonlinear node dynamics is studied.A suitable functional state observer is constructed with the limited measurement.The parameters of the designed functional observer are obtained from the algebraic method and the stability of the functional observer is proven by the Lyapunov theorem.Some necessary conditions that need to be satisfied for the design of the functional state observer are obtained.Different from previous studies, in the multi-layer complex dynamical network with nonlinear node dynamics, the proposed method can estimate the state of target variables on some layers directly instead of estimating all the individual states.Thus, it can greatly reduce the placement of observers and computational cost.Numerical simulations with the three-layer complex dynamical network composed of three-dimensional nonlinear dynamical nodes are developed to verify the effectiveness of the method.

Damage of multi-layer spaced metallic target plates impacted by radial layered PELE

Three different kinds of PELE(the penetrator with lateral efficiency) were launched by ballistic artillery to impact the multi-layer spaced metal target plates.The lmpact velocities of the projectiles were measured by the velocity measuring system.The damage degree and process of each laye r of target plate impacted by the three kinds of projectiles were analyzed.The experimental results show that all the three kinds of projectiles have the effect of expanding holes on the multi-layer spaced metal target plates.For the normal structure PELE(without layered) with tungsten alloy jacket and the radial layered PELE with tungsten alloy jacket,the diameters of holes on the seco nd layer of plates are 3.36 times and 3.76 times of the diameter of the projectile,re spectively.For radial layered PELE with W/Zr-based amorphous composite jacket,due to the large number of tungsten wires dispersed after the impact,the diameter of the holes on the four-layer spaced plates can reach 2.4 times,3.04 times,5.36 times and 2.68 times of the diameter of the projectile.Besides,the normal structure PELE with tungsten alloy jacket and the radial layered PELE whit tungsten alloy jacket formed a large number of fragments impact marks on the third target plate.Although the number of fragments penetrating the third target plate is not as large as that of the normal structure PELE,the area of dispersion of fragments impact craters on the third target plate is larger by the radial layered PELE.The radial layered PELE with W/Zr-based amorphous composite jacket released a lot of heat energy due to the impact of the matrix material,and formed a large area of ablation marks on the last three target plates.

Multi-layer phenomena in petawatt laser-driven acceleration of heavy ions

Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW laser-accelerated heavy particles using different nanoscale short targets with a thickness of 100 nm Cr, Fe, Ag, Ta, Au, Pb, Th and U, as well as 200 nm thick Al and Ca. An obvious stratification is observed in the simulation. The layering phenomenon is a hybrid acceleration mechanism reflecting target normal sheath acceleration and radiation pressure acceleration, and this phenomenon is understood from the simulated energy spectrum,ionization and spatial electric field distribution. According to the stratification, it is suggested that high-quality heavy-ion beams could be expected for fusion reactions to synthesize superheavy nuclei. Two plasma clusters in the stratification are observed simultaneously, which suggest new techniques for plasma experiments as well as thinner metal targets in the precision machining process.

Physical and numerical investigations of target stratum selection for ground hydraulic fracturing of multiple hard roofs

Ground hydraulic fracturing plays a crucial role in controlling the far-field hard roof,making it imperative to identify the most suitable target stratum for effective control.Physical experiments are conducted based on engineering properties to simulate the gradual collapse of the roof during longwall top coal caving(LTCC).A numerical model is established using the material point method(MPM)and the strain-softening damage constitutive model according to the structure of the physical model.Numerical simulations are conducted to analyze the LTCC process under different hard roofs for ground hydraulic fracturing.The results show that ground hydraulic fracturing releases the energy and stress of the target stratum,resulting in a substantial lag in the fracturing of the overburden before collapse occurs in the hydraulic fracturing stratum.Ground hydraulic fracturing of a low hard roof reduces the lag effect of hydraulic fractures,dissipates the energy consumed by the fracture of the hard roof,and reduces the abutment stress.Therefore,it is advisable to prioritize the selection of the lower hard roof as the target stratum.

An Experimental and Numerical Study on the Ballistic Performance of Multi-Layered Moderately-Thick Metallic Targets against 12.7-mm Projectiles

Themain goal of this work is to study the ballistic performance ofmulti-layered moderately-thick metallic targets.Several target configurations have been considered in thiswork,with various types of interlayer connection(spaced,contacted and adhesive)and the number of layers(four and eight),and the influence of target configurations on ballistic performance has been studied experimentally and numerically.In the experiments,the targets were impacted by 12.7-mm projectiles at a velocity around 820 m/s.The experimental results show that,with similar total thickness,the contacted and adhesive targets exhibit better ballistic performance than the monolithic targets,and the four-layered targets are better than the eight-layered targets with the same connection type.To explore the ballistic resistance mechanism,numerical method has been used to simulate the penetration process of each target.The numerical results indicate that petal formation and friction have significant influence on targets’ballistic performance.Friction has stronger influence on themulti-layered targets than on themonolithic ones.According to the numerical results,about 14%of projectile’s initial kinetic energy is dissipated by friction during penetrating the four-layered contacted target,which is proved to be the most effective type of target studied in thiswork.The results also indicate that,in contrast to common understanding,friction plays an important role even when the impact velocity is significantly higher than the ballistic limit.The outcome of this work may provide useful information for a better understanding of ballistic resistant mechanisms and more efficient utilization of multi-layered metallic targets in armor structural design.

Strength prediction of multi-layered copper-based composites fabricated by accumulative roll bonding

This work aims to evaluate the feasibility of the fabrication of nanostructured Cu/Al/Ag multi-layered composites by accumulative roll bonding(ARB),and to analyze the tensile properties and electrical conductivity of the produced composites.A theoretical model using strengthening mechanisms and some structural parameters extracted from X-ray diffraction is also developed to predict the tensile strength of the composites.It was found that by progression of ARB,the experimental and calculated tensile strengths are enhanced,reach a maximum of about 450 and 510 MPa at the fifth cycle of ARB,respectively and then are reduced.The electrical conductivity decreased slightly by increasing the number of ARB cycles at initial ARB cycles,but the decrease was intensified at the final ARB cycles.In conclusion,the merit of ARB to fabricate this type of multi-layered nanocomposites and the accuracy of the developed model to predict tensile strength were realized.

Effective depth-of-penetration range due to hardness variation for different lots of nominally identical target material

The effect of small variations of target hardness on the depth of penetration for nominally identical target material has not been addressed systematically in publications yet and is often neglected. An investigation of this issue for laboratory-scale long rod projectiles penetrating into semi-infinite rolled-homogeneous-armor steel targets was conducted. The tungsten-heavy-alloy penetrators were of length 90 mm and diameter6 mm. Five lots of armor steel with a nominal hardness range of 280–330 BHN provided material for the targets. The pursued approach consisted of hardness testing of the targets, in total 17 ballistic experiments at velocities in between 1250 m/s and 1780 m/s and data analysis.A linear regression analysis of penetration vs. hardness shows that a target hardness increase within the given range of 280–330 BHN may result in a reduction of penetration depth of about 5.8 mm at constant velocity. This is equal to a change of-12% at an impact velocity of 1250 m/s. A multiple linear regression analysis included also the influence of yaw angle and impact velocity. It shows that small yaw angles and slight variations of impact velocities provide a smaller variation of the semi-infinite penetration depths than a variation of target hardness within a typical specification span of 50 BHN. For such a span a change in penetration of approximately-4.8 mm due to hardness variation is found, whereas 1°of yaw angle or-10 m/s of velocity variation gives a change of about-1.0 mm respectively-0.9 mm. For the given example, the overwhelming part of the variation is to be attributed to hardness effects – 4.8 mm out of 5.8 mm(83%). For nominally identical target material the target hardness thus influences the ballistic test results more severely than the typical scatter in impact conditions.

Intelligent Detection Method of Substation Environmental Targets Based on MD-Yolov7

The complex operating environment in substations, with different safety distances for live equipment, is a typical high-risk working area, and it is crucial to accurately identify the type of live equipment during automated operations. This paper investigates the detection of live equipment under complex backgrounds and noise disturbances, designs a method for expanding lightweight disturbance data by fitting Gaussian stretched positional information with recurrent neural networks and iterative optimization, and proposes an intelligent detection method for MD-Yolov7 substation environmental targets based on fused multilayer feature fusion (MLFF) and detection transformer (DETR). Subsequently, to verify the performance of the proposed method, an experimental test platform was built to carry out performance validation experiments. The results show that the proposed method has significantly improved the performance of the detection accuracy of live devices compared to the pairwise comparison algorithm, with an average mean accuracy (mAP) of 99.2%, which verifies the feasibility and accuracy of the proposed method and has a high application value.

侵彻弹体过载信号特性与处理技术研究进展

侵彻弹体过载信号是反映侵彻物理过程的关键信号,可分为刚体减速度、弹体结构响应、连接结构响应和传感器噪声4种成分。介绍了4种成分的来源和各自特点,讨论了弹体结构响应和传感器相关信号各自的建模和评估方法。整理了针对过载信号进行分析处理的若干方法,比较了各种方法的精确性、自适应性、实时性和适用范围。对于过载信号处理实时性需求、重构手段、刚体减速度在复杂侵彻环境下的形式以及高速侵彻对过载信号分析处理带来的挑战展开了讨论。针对侵彻弹体过载信号研究现状,总结了存在的问题以及未来可能的研究方向。

基于DnCNN 的侵彻过载时频去噪方法

目的提高从侵彻过载中准确估计刚体过载信号的能力。方法提出一种基于前馈去噪卷积神经网络(DnCNN)的侵彻过载时频去噪方法,该方法首先应用短时傅里叶变换(STFT)提取侵彻过载信号的时频图像,使DnCNN能够充分利用时频图像信息,估计出刚体过载时频图像。最后,通过逆STFT将时频图像转换回时域,得到估计的刚体过载信号。结果在5-Fold交叉验证中,所提方法在测试集上的平均绝对误差(MAE)为0.968%,Pearson相关系数(r)为90.35%。与低通滤波、总体经验模态分解(EEMD)和小波变换方法相比,所提方法的平均MAE分别降低了1.82%、1.00%、0.75%,平均相关系数r值分别提高了47.81%、17.48%、22.93%。结论所提方法可以从侵彻过载中准确估计出刚体过载信号,在去噪能力上优于低通滤波、EEMD和小波变换方法,且在去噪过程中,无需调整参数,能够自动完成去噪任务。

穿越多种典型地层的跨海超大直径泥水盾构选型及针对性设计——以青岛胶州湾第二海底隧道为例

为缓解海底隧道盾构段施工中存在的关键问题,以青岛胶州湾第二海底隧道TJ-06标段为实际工程背景,针对“深蓝号”超大直径泥水平衡式盾构长距离、高水压穿越上软下硬土岩复合地层、全断面凝灰岩、断层破碎带、全断面花岗岩时的刀盘刀具磨损、刀具破岩能力不足、泥水舱滞排、刀盘泥饼堵塞和盾尾密封失效与主驱动密封失效等关键问题与难点进行针对性设计与研究,采取减小刀间距、优化刀具布置与形式、采用大直径短螺旋后接颚式破碎机排渣模式、加强并优化刀盘与泥水舱的冲刷等设计方案,实现了降低能耗、减少刀具损坏、缓解泥水舱滞排、提高施工效率,并极大地确保了施工安全的实施效果。

基于小波系数的粘连信号穿层特征提取方法

针对侵彻多层硬目标过程引信信号处理中层与层之间的过载相互粘连的问题,提出基于小波系数的粘连信号穿层特征提取方法。该方法以小波基函数重构信号能力和提取穿层特征能力作为处理粘连信号时最优小波基的选择依据,使用选取的最优小波基db10对粘连信号进行小波分解,提取含穿层信息的刚体减加速度信号分量对应的小波系数。Matlab仿真表明,通过db10小波分解重构得到侵彻过程中弹体的刚体减加速度信号(即A6信号),提取A6信号对应的小波系数ca6,清晰地表述了穿层特征。

硬目标侵彻引信炸点控制方法综述

为使读者对硬目标侵彻引信有较全面的了解,综述了硬目标侵彻引信发展现状,及其计时、空穴识别、计层、计行程、定深和介质识别等6种起爆方式。

地下硬目标毁伤分析

分类研究了深层目标,讨论分析了目标易损面积及纯易损面积、结构毁伤、功能毁伤的概念,指出了目标易损面积与命中条件下的毁伤概率的相关性;构造了可以描述目标易损性的数学函数,理论上可通过对f(μ)的分析,了解目标易损性变化规律,方便描述目标的毁伤过程,预测目标的毁伤状况。

空地导弹对飞机掩蔽库的毁伤效能评估

针对典型飞机掩蔽库目标,研究空地导弹对两种不同停放方式飞机的毁伤效能评估方法。首先定义了飞机的毁伤等级,其次构建了聚能侵彻战斗部对飞机掩蔽库的毁伤模型。最后通过蒙特卡罗仿真方法研究空地导弹对掩体内停放飞机的毁伤效果,并且计算了导弹的杀伤概率。仿真结果表明所建模型和采用的评估方法具有较强实用性和可操作性。

射频磁控溅射(Ti,Al)N薄膜性能的研究

采用射频磁控溅射,用Al靶和Ti靶同时溅射沉积(Ti,Al)N薄膜。研究表明:不同Al靶功率沉积的薄膜中始终存在面心立方结构(B1型),当Al靶功率大于250 W薄膜中面心立方结构(B1型)和六方结构(B4型)共存。随Al成分的增加,B1型结构晶格常数减小,薄膜择优取向由B1型(111)向B4型(002)转变。薄膜表面随Al靶功率增加分别呈岛状、纤维状和柱状增长。(Ti,Al)N薄膜的硬度随Al靶功率的增加呈上升趋势。等离子体发射光谱分析显示,在相同工艺条件下Al靶比Ti靶先进入非金属态溅射模式,导致在相同功率下Al溅射速率低于Ti溅射速率。

刚玉块石混凝土抗弹丸侵彻效应试验研究

块石混凝土由于取材方便、工艺简单等特点,作为遮弹材料一直为人们所关注。但块石自身强度有限,对于大威力的现代弹种,遮弹效果受到了一定限制,以致实际工程中块石混凝土遮弹层厚度太大,施工不便,影响了块石混凝土遮弹层的应用。刚玉块石具有强度高、硬度大等独特的力学性能,利用它代替块石混凝土中的普通块石,研制成一种由刚玉块石和混凝土共同浇注组成的抗侵彻复合材料。为了研究这种新型材料的防护性能,对混凝土和刚玉块石混凝土进行了实弹射击对比试验。制作了刚玉块石混凝土靶体6块,混凝土靶体3块,使用坦克炮发射φ125模拟弹。结果表明,刚玉块石混凝土具有优良的抗侵彻性能,它能够使弹体破坏、变形或跳弹。提高侵彻速度,刚玉块石混凝土靶体破坏情况变化不明显,表明刚玉块石混凝土对抵抗更高速度的弹丸侵彻有效。与相同强度等级混凝土相比,刚玉块石混凝土靶体侵彻深度减小很多。整块刚玉块石完全能够阻止弹丸的侵入。研究成果可为刚玉块石混凝土遮弹层的工程应用和深入理论分析提供依据。

基于Choi-Williams分布的侵彻层数识别方法

针对侵彻多层硬目标过程中实测加速度信号的振荡叠加,以及可能引起的层数误判问题,采用时频分析法研究弹体主轴方向加速度信号的Choi-Williams能量分布特征,提出了以侵彻过程加速度信号的能量分布为依据的层数识别方法。侵彻8层等间距混凝土靶板的实测数据处理结果表明,该方法可快速准确实现层数识别,解决了低通滤波方法无法获取准确层数信息的问题,为实时控制起爆位置提供依据。

侵彻硬目标武器及其智能引信关键技术研究

探讨了侵彻硬目标武器的发展背景、发展现状以及发展趋势,重点对其所配用的硬目标智能引信进行分析,阐述了硬目标智能引信的功能组成,并结合相关基础研究工作,总结了硬目标智能引信研制过程中需解决的关键技术,提出了在硬目标智能引信研制过程中应以动力学仿真为主、结合必要试验的研究方法。