长杆高速侵彻问题研究进展

由高密度金属制成的长杆弹在1.5$\sim$3.0km/s的下具有很强的侵彻和贯穿能力,长杆高速侵彻问题现已成为穿甲侵彻领域的研究热点.本文综述了长杆高速侵彻问题的最新研究进展,首先介绍了长杆高速侵彻的基本概念、研究方法和理论模型;其次重点论述了研究中关注的突出问题与应用, 包括弹靶材料性质、长杆弹头部形状、长径比效应与分段杆设计、陶瓷靶抵抗长杆侵彻与界面击溃和非理想长杆侵彻;最后对未来的研究工作提出一些建议.      

破片撞击起爆柱面带壳装药的临界速度修正判据

为获得适用于柱面带壳装药的冲击起爆修正判据，以Picatinny工程判据为基础加入修正项进行修正。采用AUTODYN-3D软件对破片撞击柱面带钢壳的B炸药进行数值计算，获得了破片入射角、装药曲率半径对炸药临界起爆速度的影响规律；通过拟合得到修正项表达式，建立了考虑破片入射角、柱壳装药形状函数的炸药起爆临界速度修正判据。判据计算值与实验数据和数值计算值吻合较好，该判据能较好的预测柱形带壳装药的冲击起爆条件。     

旋转射弹高速倾斜入水多相流场与弹道数值模拟

基于VOF多相流模型和有限体积法求解水、汽、气多相流动的RANS方程，结合重叠网格技术和six DOF算法对某一型号舰载射弹倾斜入水过程进行数值模拟研究。首先基于该方法研究了射弹旋转效应对射弹运动特性及流体动力特性的影响，然后对不同入水角下倾斜入水过程进行分析，得到不同倾角下旋转射弹入水空泡形态发展规律、弹体运动特征及流体动力特性变化规律。研究结果表明:射弹的旋转有利于弹体在初始对称面内的弹道稳定性，但会降低弹体侧向稳定性，使射弹受到的阻力系数、俯仰力矩系数变小；入水角越小，形成的空泡越不对称，由射弹运动状态的改变引起的空泡形态变化越明显，在超空泡航行阶段，弹体运动较稳定，不同角度下流体动力系数差别很小，当弹体下表面刺破空泡壁沾湿时，弹体运动状态发生较大变化，流体动力系数迅速增大，此时入水角度过小，弹体容易失稳；弹体的沾湿对空泡形态、弹体运动稳定性和流体动力特性有着重要的影响。     

爆炸荷载下基于细观建模的素/钢筋混凝土板破坏模式

为了获得爆炸荷载下细观结构对素/钢筋混凝土板的影响，采用随机骨料投放建立了素/钢筋混凝土板细观模型。利用LS-DYNA对基于细观建模的钢筋混凝土板进行爆炸荷载作用下的数值模拟，通过与实验以及均质建模方法进行比较，验证了细观建模方法的准确性。进而研究了基于细观建模的素/钢筋混凝土板在不同爆炸荷载下的结构响应，获得了素/钢筋混凝土板的响应过程和破坏模式。结果表明:在低药量（1、2 kg）爆炸荷载下，细观结构对素/钢筋混凝土板的影响较小，其破坏模式以纵横塑性铰线破坏为主，药量越大，铰线越多；在高药量（5、10和15 kg）爆炸荷载下，细观结构对素/钢筋混凝土板的影响较大，与均质模型相比存在较大差异，细观素/钢筋混凝土板以爆坑为中心，产生环向与径向裂纹，药量越大，圆坑越大，裂纹越多，板局部破坏越严重。     

Viscous Shock Wave to an Inflow Problem for Compressible Viscous Gas with Large Density Oscillations

Acta Mathematicae Applicatae Sinica, English Series - This paper is concerned with the inflow problem for one-dimensional compressible Navier-Stokes equations. For such a problem, Huang, Matsumura,...     

Isogeometric vibration and buckling analyses of curvilinearly stiffened composite laminates

Isogeometric analysis (IGA) with the polynomial splines over hierarchical T-meshes (PHT-splines) is used to provide an efficient tool capable of carrying out the vibration and buckling analyses of the stiffened laminates. IGA offers increased accuracy and efficiency using the PHT-splines, which represent exact geometry of the stiffeners and make the refinement more flexible near the areas where the stiffeners and composite plate are connected. Numerical examples are given to validate the correctness and superiority of the present method, comparing with the results from existing literatures and commercial softwares. Besides, the influences of the orientation, curvature, location and cross-section size of the stiffeners on the natural frequencies and buckling loads are also studied. The results show that the optimization of the shape and size of the stiffeners has an important effect on the vibration and buckling characteristics of stiffened laminates.     

Construction of ZIF-8/AuNPs/PVP–rGO/GCE Electrochemical Sensor and Its Sensitive Determination of Salbutamol

Russian Journal of Electrochemistry - An excellent electrochemical sensor based on glassy carbon electrode (GCE) modified in order with polyvinyl pyrrolidone-dispersed reduced graphene oxide...     

Testing Serial Correlation in Partially Linear Additive Models

Acta Mathematicae Applicatae Sinica, English Series - As an extension of partially linear models and additive models, partially linear additive model is useful in statistical modelling. This paper...     

Cutoff Phenomenon for Nearest Lamperti’s Random Walk

Methodology and Computing in Applied Probability - We consider transient neighbor random walks on the positive part of the real line, the transition probability is state dependent being a special...     

Hydrogen-induced dynamic slowdown of metallic glass-forming liquids

Dynamics of hydrogen doped Cu_(50) Zr_(50) glass-forming liquids are investigated by using the newly developed modified embedded atomic method(MEAM) potential based on molecular dynamics simulations. We find that the doping of hydrogen atoms slows down the relaxation dynamics, reduces the fragility of supercooled melts, and promotes the occurrence of glass transitions. The dynamic slowdown is suggested to be closely related to the effect of hydrogen atoms on locally ordered structure of melts. With increasing concentration of hydrogen, the five-fold symmetry associated with Cu-and Zr-centered polyhedrons is lowered, on the other hand, the local order featuring metal hydrides is enhanced. The latter dominates the dynamic behaviors of glass-forming liquids, especially for Zr atoms, and results in the dynamic slowdown.