基于中低分辨率卫星影像中舰船目标识别方法

目前,中低分辨率成像侦察卫星已经成为远距离情报保障的重要手段之一。然而,中低分辨率成像侦察卫星对海上机动舰船的侦察存在目标检测、识别难等问题,大大影响了情报使用效益。针对上述问题,提出基于霍夫变换的舰船开尔文尾迹提取方法,用于匹配并识别舰船型号。通过仿真得出不同型号舰船的开尔文尾迹尖头波平均距离,可以有效的识别出真实遥感影像中舰船属性,与实际影像数据对比分析,证明上述算法具有一定可行性。因此,基于霍夫变换的舰船开尔文尾迹提取方法可以在一定条件下基本实现目标舰船型号的识别,提升中低分辨率成像侦察卫星对海上机动舰船目标的识别准确率。

环氧树脂基近红外吸收涂层的近红外光谱、力学及耐盐水性能研究

以环氧树脂为粘合剂,Sm2O3为功能颜料,硅烷偶联剂和石墨烯为改性剂,制备得到了一种同时具有突出力学性能和耐盐水性能的近红外低反射率涂层。系统研究了Sm2O3添加量、硅烷偶联剂种类、硅烷偶联剂添加量和石墨烯添加量对涂层性能的影响。结果表明:Sm2O3添加量的增加可明显降低涂层对1.06μm近红外光的反射率,当Sm2O3添加量为50%,涂层对1.06μm近红外光的反射率可低至31.2%。此时,涂层的附着力和耐冲击强度分别可达到1级和50 kg·cm。用硅烷偶联剂改性涂层,偶联剂上的强极性基团分别可与涂层中的树脂基体和颜料形成共价键结合,从而可发挥桥连作用,进而可明显改善涂层的柔韧性,其中KH560的改性效果最佳。当KH560添加量为5%,涂层的柔韧性可从改性前的9 mm显著改善为改性后的4 mm。石墨烯具有特殊的共平面结构和超长共轭结构特征,使其对入射光的吸收可延伸到近红外区域。石墨烯特殊的片层结构使其具有很高的耐冲击强度和柔韧性,在涂层中添加石墨烯可明显改善涂层的力学性能。研究发现石墨烯的添加可在进一步改善涂层力学性能的前提下显著降低涂层对1.06μm近红外光的反射率。当石墨烯添加量为8%,涂层对1.06μm近红外光的反射率可低至12.6%,此时涂层可具备突出的激光隐身效能。同时,涂层的附着力、柔韧性和耐冲击强度分别可达到1级、2 mm和50 kg·cm,可很好地满足实际工程应用要求。在环氧树脂、硅烷偶联剂和石墨烯的协同界面优化作用下,最佳配方(Sm2O3添加量为50%、KH560添加量为5%、石墨烯添加量为8%)的涂层经盐水腐蚀21 d后,涂层的微结构、近红外低反射率性能和力学性能可保持稳定。此时,涂层对1.06μm近红外光的反射率为12.47%,涂层的附着力、柔韧性和耐冲击强度分别可保持在1级、2 mm和45 kg·cm,表明制备的涂层具有良好的耐盐水性能。

Dynamic response of honeycomb-FGS shells subjected to the dynamic loading using non-polynomial higher-order IGA

The main goal of this study is to use higher-order isogeometric analysis(IGA)to study the dynamic response of sandwich shells with an auxetic honeycomb core and two different functionally graded materials(FGM)skin layers(namely honeycomb-FGS shells)subjected to dynamic loading.Touratier's non-polynomial higher-order shear deformation theory(HSDT)is used due to its simplicity and performance.The governing equation is derived from Hamilton's principle.After verifying the present approach,the effect of input parameters on the dynamic response of honeycomb-FGS shells is carried out in detail.

Microscopic defects formation and dynamic mechanical response analysis of Q345 steel plate subjected to explosive load

As the basic protective element, steel plate had attracted world-wide attention because of frequent threats of explosive loads. This paper reports the relationships between microscopic defects of Q345 steel plate under the explosive load and its macroscopic dynamics simulation. Firstly, the defect characteristics of the steel plate were investigated by stereoscopic microscope(SM) and scanning electron microscope(SEM). At the macroscopic level, the defect was the formation of cave which was concentrated in the range of 0-3.0 cm from the explosion center, while at the microscopic level, the cavity and void formation were the typical damage characteristics. It also explains that the difference in defect morphology at different positions was the combining results of high temperature and high pressure. Secondly, the variation rules of mechanical properties of steel plate under explosive load were studied. The Arbitrary Lagrange-Euler(ALE) algorithm and multi-material fluid-structure coupling method were used to simulate the explosion process of steel plate. The accuracy of the method was verified by comparing the deformation of the simulation results with the experimental results, the pressure and stress at different positions on the surface of the steel plate were obtained. The simulation results indicated that the critical pressure causing the plate defects may be approximately 2.01 GPa. On this basis, it was found that the variation rules of surface pressure and microscopic defect area of the Q345 steel plate were strikingly similar, and the corresponding mathematical relationship between them was established. Compared with Monomolecular growth fitting models(MGFM) and Logistic fitting models(LFM), the relationship can be better expressed by cubic polynomial fitting model(CPFM). This paper illustrated that the explosive defect characteristics of metal plate at the microscopic level can be explored by analyzing its macroscopic dynamic mechanical response.

Experimental and numerical analyses of the effect of fibre content on the close-in blast performance of a UHPFRC beam

Limited research has been conducted on the influences of fiber content on close-in blasting characteristics for ultrahigh-performance fiber-reinforced concrete(UHPFRC)beams.This paper aims to address this knowledge gap through experimental and mesoscale numerical methods.Experiments were conducted on ten UHPFRC beams built with varying steel fiber volumetric fractions subjected to close-in explosive conditions.Additionally,this study considered other parameters,such as the longitudinal reinforcement type and ratio.In the case of UHPFRC beams featuring normal-strength longitudinal reinforcement of diametersΦ12,Φ16,andΦ20,a reduction in maximum displacement by magnitudes of19.6%,19.5%,and 17.4%was observed,respectively,as the volumetric fractions of fiber increased from1.0%to 2.5%.In addition,increasing the longitudinal reinforcement ratio and using high-strength steel longitudinal reinforcement both significantly reduced the deformation characteristics and increase the blasting resistances of UHPFRC beams.However,the effects on the local crushing and spalling damage were not significant.A mesoscale finite element model,which considers the impacts of fiber parameters on UHPFRC beam behaviors,was also established and well correlated with the test findings.Nevertheless,parametric analyses were further conducted to examine the impacts of the steel fiber content and length and the hybrid effects of various types of microfibers and steel fibers on the blasting performance of UHPFRC beams.

Experimental and numerical study on protective effect of RC blast wall against air shock wave

Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.

Experimental crushing behavior and energy absorption of angular gradient honeycomb structures under quasi-static and dynamic compression

The high variability of shock in terrorist attacks poses a threat to people's lives and properties,necessitating the development of more effective protective structures.This study focuses on the angle gradient and proposes four different configurations of concave hexagonal honeycomb structures.The structures'macroscopic deformation behavior,stress-strain relationship,and energy dissipation characteristics are evaluated through quasi-static compression and Hopkinson pressure bar impact experiments.The study reveals that,under varying strain rates,the structures deform starting from the weak layer and exhibit significant interlayer separation.Additionally,interlayer shear slip becomes more pronounced with increasing strain rate.In terms of quasi-static compression,symmetric gradient structures demonstrate superior energy absorption,particularly the symmetric negative gradient structure(SNG-SMS)with a specific energy absorption of 13.77 J/cm~3.For dynamic impact,unidirectional gradient structures exhibit exceptional energy absorption,particularly the unidirectional positive gradient honeycomb structure(UPG-SML)with outstanding mechanical properties.The angle gradient design plays a crucial role in determining the structure's stability and deformation mode during impact.Fewer interlayer separations result in a more pronounced negative Poisson's ratio effect and enhance the structure's energy absorption capacity.These findings provide a foundation for the rational design and selection of seismic protection structures in different strain rate impact environments.

Capillary Property of Entangled Porous Metallic Wire materials and Its Application in Fluid Buffers:Theoretical Analysis and Experimental Study

Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).

Experimental study on the size effect on the equation of state of concretes under shock loading

Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of concrete.The experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the EoS.Although some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one size.In this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete materials.The mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the specimen.According to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.

Non-dimensional analysis on blast wave propagation in foam concrete:Minimum thickness to avoid stress enhancement

Foam concrete is a prospective material in defense engineering to protect structures due to its high energy absorption capability resulted from the long plateau stage.However,stress enhancement rather than stress mitigation may happen when foam concrete is used as sacrificial claddings placed in the path of an incoming blast load.To investigate this interesting phenomenon,a one-dimensional difference model for blast wave propagation in foam concrete is firstly proposed and numerically solved by improving the second-order Godunov method.The difference model and numerical algorithm are validated against experimental results including both the stress mitigation and the stress enhancement.The difference model is then used to numerically analyze the blast wave propagation and deformation of material in which the effects of blast loads,stress-strain relation and length of foam concrete are considered.In particular,the concept of minimum thickness of foam concrete to avoid stress enhancement is proposed.Finally,non-dimensional analysis on the minimum thickness is conducted and an empirical formula is proposed by curve-fitting the numerical data,which can provide a reference for the application of foam concrete in defense engineering.

Synthesis and microwave absorption performance of heat-treated RF/SiO_(2)aerogels

The well-designed composite with satisfactory electromagnetic microwave absorption at high temperatures remains a serious challenge.Herein,we fabricated a resorcinol-formaldehyde/silica dioxide composite aerogel(RF/SiO_(2))with a three-dimensional network structure using sol-gel,atmospheric pressure drying technique as well as heat-treated processes to achieve enhanced microwave absorption capabilities in the low frequency range.The pristine RF/SiO_(2)aerogel presented a typical micropores structure with a surface area,porous volume,and density of 146.82 m^(2)/g,62.40%,and 0.28 cm^(3)/g,respectively.Remarkably,the RF/SiO_(2)aerogel showed an effective absorption bandwidth of 3.56 GHz and a minimum reflection loss value of-46.10 d B at 2.25 mm after being heat-treated at 1500°C,while the maximum effective absorption bandwidth was 3.60 GHz at 2.30 mm.The intricate three-dimensional networks possessed remarkable impedance matching,multiple attenuation mechanisms,interfacial polarization,and dielectric loss,which were attributed to the exceptional ability to absorb electromagnetic microwaves.It offered a fresh approach to creating adaptable and effective microwave absorption materials in military defense.

基于眼动数据的空战控制能力评估方法

针对战勤人员空战控制能力评估主观评价多、客观评价少的问题,提出基于眼动数据的空战控制能力评估方法。首先将眼动要素和空战控制流程相结合建立能力素质量化评估模型;再利用熵权-变异系数法对体现能力素质的4种指标进行组合赋权,并将结果生成可视化的空战控制能力雷达图;最后通过TOPSIS法对能力素质排序结果进行验证,结果表明所提方法能够对空战控制能力提供客观评价,也为今后战勤人员空战控制能力素质评估提供了标准化依据。

基于MBD的产品设计数字化军检研究

针对传统军检技术存在质量监督方式落后的问题,就军事代表在产品设计阶段如何开展基于MBD(model baseddefinition)的数字化军检业务进行分析。梳理产品设计阶段的产出物和相应的军检点,并对军检内容、军检方式和军检对象进行研究。结果表明:在产品设计阶段开展基于MBD的数字化军检技术,可提升军事代表对装备质量的监督能力,适应基于MBD的装备研制体系,是未来军检技术的发展方向。

战场设施体系空间布局量化分析理论与方法

为解决战场设施体系空间布局定量表达与描述困难问题,运用空间统计学的理论与方法,剖析了战场设施体系的空间分布、空间依赖和空间关联等量化关系,构建了战场设施体系空间布局量化分析指标与计算分析方法,凝练出其在战场设施体系规划建设与作战运用中的策略。以典型联合作战背景下机场设施体系为例,深入研究和分析了其布局重心、布局指向、分布格局和作战覆盖范围等量化分析指标,为其体系设计、能力评估以及作战运用提供直观可视、精准可靠的信息支撑。

陆域网络化火力敏捷规划建设构想

面向未来陆战场智能精确打击网络化、自主化发展趋势,聚焦提升陆域传统火力网络化协同打击的战场适变能力,从火力指控扁平化、服务化、知识化、敏捷化发展的视角,重点探讨了面向数据化服务的网络化火力指控信息系统建设和网络化火力敏捷任务规划建设构想,提出了“云-边-端”一体化的网络化火力任务规划架构,并在此架构下,针对不同指挥层级下网络化火力自主规划个性特征,提出并分析了3种任务规划模式,来支撑一体化构想。该建设构想将为网络化火力敏捷规划提供总体技术支撑。

基于FPGA的仿造数码迷彩生成系统研究

为了解决传统仿造数码迷彩生成算法开发平台灵活性不足的问题,提出了一种基于现场可编程门阵列(FPGA)的仿造数码迷彩生成算法。采用直方图统计提取主要颜色信息,将背景图像马赛克化获得颜色分布信息,依据色差进行主色替换得到仿造数码迷彩的方法,取得了不同主色数量、色差计算权重、颜色量化数量下的数据。结果表明,颜色量化为3600种后,提取出4种主色作为仿造数码迷彩主色,根据色差主色替换时色彩权重3∶6∶1,生成的仿造数码迷彩具有良好的伪装效果,且基于FPGA实现该算法时系统占用资源少,处理800 pixels×480 pixels分辨率的单帧彩色图像所需时间仅为22.21 ms,满足动态场景下生成仿造数码迷彩的实时性需求。该研究为主动伪装技术提供了参考。

基于中继保障的分布式海战补给路径优化

分布式海战是未来战争形态发展的必然趋势。与传统海战样式相比,分布式海战作战部署更加灵活,作战区域更广。分布式海战条件下的后勤保障区域分布范围广、保障半径大、分散程度高,传统伴随保障方式难以适应战争形态发展。依托中继保障基地进行递进保障,并运用补给舰编队进行物资转运的补给模式,更加适合分布式海战特点。考虑复杂多变的海洋天气对远距离物资投送带来的极大影响,首先基于不同地理位置的历史天气信息模拟有效波高,然后根据有效波高测算天气因素对舰船航速及补给开销的影响程度,最后触发优化模型与仿真模型之间的反馈并得到优化方案。将优化方案与未触发仿真模型的理想优化结果进行比较,以验证不同策略的性能表现,得到契合实际应用环境的优化方案,从而提高最优路径的鲁棒性,为分布式海战物资补给提供较好的决策支撑。

基于机器学习的迷彩伪装效果评价方法

针对迷彩伪装效果评价算法中评价指标权重分配复杂性,算法开发平台灵活性的问题,提出了基于多特征指标决策树的评价方法。该方法依据视觉注意力机制选择纹理、颜色、亮度、结构相似度与伪装目标尺寸这5项特征作为评价指标,使用机器学习决策树分类器训练出迷彩伪装效果评价模型,将模型移植入体积小、功耗低的树莓派开发平台上。通过与均值权重法、熵权法两种评价方法进行准确率对比实验,其中均值权重法准确率为56%;熵权法准确率为74%;该方法准确率为90%。通过实时性实验证明该方法可以在场外2 s左右得到迷彩伪装效果评价结果。

模糊积分决策级融合的空地协同目标识别研究

针对单独使用无人机或无人车对目标区域侦察识别效率低、虚警率高等局限性问题,分析了多种决策级信息融合的方法,提出了基于模糊积分改进的决策级空地信息融合目标识别方法,将空地协同探测的目标类型、位置、威胁度、毁伤程度等信息进行融合识别并输出。仿真结果表明,该算法有效完善了目标信息,提高了目标特征信息识别准确性,降低了虚警率。

基于超效率DEA模型的陆军部队指挥所指挥效率评价

指挥所指挥效率评估是复杂的系统性问题,对提高部队指挥、作战、保障能力具有重要意义。主要运用数据包络的方法,不探讨指挥所的内部结构问题,通过对陆军典型部队指挥所输入输出数据进行分析,运用CCR-DEA和超效率DEA模型,对指挥效率问题进行研究排序,并针对输入数据提出改进建议,评估方法简单、可操作性强,对于陆军部队指挥所构建和指挥能力提升具有重要意义。