Irreversible demagnetization mechanism of permanent magnets during electromagnetic buffering

The permanent magnets will be irreversibly demagnetized under high temperature and high velocity during the electromagnetic buffering. In this study, the magnetic field induced by eddy currents and the self-demagnetizing field of permanent magnet are taken into consideration together for demagnetiza-tion analyse. The magnetic Reynolds number is used to express the eddy currents demagnetization. The correction coefficient being expressed as the index of the air-gap width, the inner cylinder thickness, iron pole axial length and the permanent magnet demagnetization coefficient is introduced by magnetic path analysis to represent the self-demagnetization effect and the demagnetization extent. The electromag-netic buffer (EMB) prototype is tested under intensive impact loads of different strengths at room temperature. The accuracy of the nonlinear irreversible demagnetization finite element model is verified by demagnetization on damping force, velocity and displacement. Finally, high-velocity demagnetization and high-temperature demagnetization are analysed in order to obtain the distribution law of irre-versible demagnetization.     

Numerical simulation study on penetration performance of depleted Uranium (DU) alloy fragments

Due to its high strength, high density, high hardness and good penetration capabilities, Depleted ura-nium alloys have already shined in armor-piercing projectiles. There should also be a lot of room for improvement in the application of fragment killing elements. Therefore, regarding the performance of the depleted uranium alloy to penetrate the target plate, further investigation is needed to analyze its advantages and disadvantages compared to tungsten alloy. To study the difference in penetration per-formance between depleted uranium alloy and tungsten alloy fragments,firstly, a theoretical analysis of the adiabatic shear sensitivity of DU and tungsten alloys was given from the perspective of material constitutive model. Then, taking the cylindrical fragment penetration target as the research object, the penetration process and velocity characteristics of the steel target plates penetrated by DU alloy frag-ment and tungsten alloy fragment were compared and analyzed, by using finite element software ANSYS/LS-DYNA and Lagrange algorithm. Lastly, the influence of different postures when impacting target and different fragment shapes on the penetration results is carried out in the research. The results show that in the penetration process of the DU and tungsten alloy fragments, the self-sharpening properties of the DU alloy can make the fragment head sharper and the penetrating ability enhance. Under the same conditions, the penetration capability of cylindrical fragment impacting target in vertical posture is better than that in horizontal posture, and the penetration capability of the spherical fragment is slightly better than that of cylindrical fragment.     

次声波技术与心理战应用

次声波是一种频率变化范围在10?4 Hz～20 Hz之间的声波,它具有穿透力强、传输距离远以及不易被吸收的特点,以此制造的次声波武器伤人但不毁物。近年来,随着高新技术的不断发展,次声波武器在心理战领域得到了广泛应用。本文首先对次声波技术及次声波武器的概念进行了简要介绍;其次,研究了次声波的生物学效应,分析了次声波频率、声压强度以及作用时间与生物学效应的关系,发现三种次声波的作用参数与生物学效应之间的关系虽然错综复杂,但也有一定规律可循;最后,提出了次声波武器在心理战的三个潜在应用前景,即利用次声波穿透力强的特点发展对掩体人员作战的心理战装备、利用次声波的生物学效应发展反恐作战的心理战装备以及利用次声波的生理致伤机理发展心理战防护装备。     

Visual SLAM in dynamic environments based on object detection

A great number of visual simultaneous localization and mapping (VSLAM) systems need to assume static features in the environment. However, moving objects can vastly impair the performance of a VSLAM system which relies on the static-world assumption. To cope with this challenging topic, a real-time and robust VSLAM system based on ORB-SLAM2 for dynamic environments was proposed. To reduce the influence of dynamic content, we incorporate the deep-learning-based object detection method in the visual odometry, then the dynamic object probability model is added to raise the efficiency of object detection deep neural network and enhance the real-time performance of our system. Experiment with both on the TUM and KITTI benchmark dataset, as well as in a real-world environment, the results clarify that our method can significantly reduce the tracking error or drift, enhance the robustness, accuracy and stability of the VSLAM system in dynamic scenes.     

网络空间军备控制研究现状及启示思考

随着网络技术的发展,国际间基于网络空间进行的攻击与防卫行动愈演愈烈。在短短十数年间,网络空间行动的模式,已经由简单的宣传和窃密发展为某一国家主体或国际组织基于自身利益的考虑,对另一国家主体或国际组织在经济、军事、行政等领域进行破坏与瘫痪的军事行动。而且这种网络攻击行动的地位和作用越来越具有战略意义,正逐渐成为一种新的战争形态。文章梳理了美国和俄罗斯在网络空间军备控制方面的研究现状,并对我国如何应对这种形势提出了一些思考。     

某型矿用车辆油气弹簧阻尼可变方案设计

为实现某型矿用车辆油气弹簧阻尼可变,设计了一种机械机构,并对其结构与工作原理进行了分析:首先对油气弹簧的阻尼特性进行分析,根据计算结果确立了油气弹簧的改进目标;基于改变油液节流面积来改变阻尼特性的原理,设计了油气弹簧阻尼可变的方案,并通过计算验证了其可行性;利用Matlab/Simulink软件对油气弹簧的外特性进行了仿真分析.结果表明:油气弹簧的阻尼在改变后,空车的阻尼特性得到了改善,车辆乘坐的舒适性有所提高.     

太阳能光电热系统换热器性能实验研究

设计了新型半圆管形式的不锈钢板式换热器,对其作为太阳能光电热综合利用一体化系统集热组件的性能进行实验研究。通过新型集热光电热组件及光电组件系统的对比实验,研究该光电热组件在重庆地区夏季应用情况,分析其光电和光热特性。结果表明:在以晴朗为主的天气,半圆管形式的不锈钢板式光电热组件电热系统的电热性能与光电组件系统的相比较,前者的太阳能电池输出功率提高约26.48%,热利用效率提高23.70%以上,新型半圆管形式的光电热组件整体光电热(光电+光热)综合效率可达到25.70%,有效提高了光电热系统的综合效率。新型半圆管形式不锈钢板式换热器的换热面积增大,提高了换热效率,为太阳能光电热综合利用一体化系统在重庆等太阳辐射强度较小地区的应用提供了参考。     

钢质油罐底板腐蚀概率估计

针对钢质油罐底板腐蚀,首先分析了油罐底板腐蚀工程检测数据的特点和腐蚀试验数据统计分析理论;然后针对工程检测信息不完全的特性,以最大腐蚀深度的预测估计为目标,建立了以轻微腐蚀面积估计来实现腐蚀概率修正估计的模型;最后利用广州等地27个罐约900条检测数据估计了油罐底板的最大腐蚀深度。其最大相对误差小于45%,约80%的相对误差优于30%。     

偏振态演化对量子密钥分发影响分析

为了解决量子密钥分发(QKD)系统中的偏振态演化问题,文中分析了偏振态演化所引起的量子误码率问题,提出了通过电动偏振控制器的搜索跟踪算法来训练光纤链路的方法,达到抵消系统中存在的各种双折射的效果,将因双折射所引起的误码率从7%降至0.8%,大大提高了密钥分发的有效性。实验结果证明该方法能够有效解决QKD中的偏振态演化问题。     

一种新的证据K-NN数据分类算法

K近邻分类算法已被广泛应用于模式识别中。为了有效处理识别问题中的不确定信息并提高数据分类精度,提出了一种新的证据K-NN(NEK-NN)分类算法。首先从总的训练集中随机重复采样来构造多个训练样本子集。在每个训练子集中,利用目标数据与其各个近邻的距离分别构造基本置信指派,并根据K个近邻数据在每个类别中的数目来对构造的置信指派进行加权。然后,利用DS规则对加权证据融合。根据每个训练子集下融合结果的算术平均值来判断目标的类别属性。通过模拟数据集和真实数据集的实验,将NEK-NN算法与其他几种常见的方法做了对比分析,结果表明NEK-NN算法能够有效地提高分类的精度。