An internal ballistic model of electromagnetic railgun based on PFN coupled with multi-physical field and experimental validation

To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried out.Various test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of rail.Combining the simulation results and experimental data,the damage condition of the contact surface is analyzed.

Mussel-inspired PTW@PDA composites for developing high-energy gun propellants with reduced erosion and enhanced mechanical strength

The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.

One-step green method to prepare progressive burning gun propellant through gradient denitration strategy

Gradiently denitrated gun propellant(GDGP)prepared by a“gradient denitration”strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant.Currently,the preparation of GDGP employed a tedious two-step method involving organic solvents,which hinders the large-scale preparation of GDGP.In this paper,GDGP was successfully prepared via a novelty and environmentally friendly one-step method.The obtained samples were characterized by FT-IR,Raman,SEM and XPS.The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant,with a well-preserved nitrocellulose structure.The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance,as confirmed by oxygen bomb and closed bomb test.At the same time,the effects of different solvents on the component loss of propellant were compared.The result showed that water caused the least component loss.Finally,the stability of GDGP was confirmed by methyl-violet test.This work not only provided environmentally friendly,simple and economic preparation of GDGP,but also confirmed the stability of GDGP prepared by this method.

Development and simulation of a gridded thermionic cathode electron gun for a high-energy photon source

A gridded thermionic cathode electron gun was developed for the linear accelerator of the High Energy Photon Source(HEPS).An electron gun should provide a large maximum bunch charge with a wide adjustable range.To satisfy these requirements,the shape of the electrode was optimized using a multi-objective genetic algorithm.A large bunch charge with an adjustable range was achieved using the grid-limited gun,the flow of which was analyzed using 3-D simulations.The electron gun has been manufactured and tested,and the measured data of the grid-limited current and simulation results are compared and discussed in this study.

Analysis of Corrosion Mechanisms of Low-cement or No-cement Al_(2)O_(3)-MgO Gunning Mix with Special Calcined Alumina in Rotary Slag Test

Al_(2)O_(3)-MgO and Al_(2)O_(3)-spinel low cement castables(LCC-AM and LCC-AS)have been extensively used in steel ladles as working linings.Nevertheless,the use of alumina-magnesia gunning mixes has been mainly kept for maintaining these castable linings,because of high rebound loss,poor green strength,high porosity and short life-span.Thanks to a high BET alumina(MC-G),it is now possible to develop a series of high-performance no-cement or low-cement Al_(2)O_(3)-MgO gunning mixes(NCG-AM or LCG-AM).The paper focuses on the BOF slag resistance of NCG-AM,LCG-AM,LCC-AM and LCC-AS.The corrosion mechanisms of rotary slag samples were studied by scanning electron microscopy(SEM/EDS).The results reveal different microstructures around MgO particles,depending on the four used compositions.Continuous and thicker spinel phases were formed in NCG-AM,which was proved to have the best corrosion resistance after the dynamic slag test.MC-G can provide a high diffusion flux of Al^(3+)in terms of kinetics and hence inhibits Kirkendall porosity around MgO particles.In addition,a continuous spinel phase acts like a pinning nail to reinforce the matrix and thus decreases erosion by slag.In contrast to NCG-AM,the porous spinel phase was found around unreacted MgO particles and some particles were carried away near the interface of LCC-AM and slag.The NCG-AM containing MC-G had been tested in two steel plants,and it extended the service life of the ladles up to 50%.In addition,this study suggests the potential application of NCG-AM as steel ladle linings.

一种民用无人机反制系统的设计

本文设计了一种民用无人机反制系统,用于保护重点区域的低空空域安全。系统基于软件无线电理念设计:软件平台使用GUN Radio,硬件平台使用Hack RF。文章分析了驱离迫降民用无人机的原理,详细阐述了模拟GPS信号和产生宽带噪声信号的方法,通过理论计算推断系统的输出功率,系统理论上可对100 m范围内的民用无人机进行反制。经验证,系统可实现对无人机的驱离迫降,达到反制效果。系统方案简洁、成本低,可推广至类似的项目研究领域,具有较高的研究价值。

基于研制阶段数据融合的舰炮制导弹药测试性评估方法

针对小子样条件下开展测试性评估存在数据冲突的问题,提出一种基于研制阶段数据融合的舰炮制导弹药测试性评估方法。首先,确定研制阶段中舰炮制导弹药测试性信息的来源,并根据其不同特点,利用相应的Beta分布参数折合方法,获得测试性信息Beta分布并构造对应的基本信任分配函数。其次,为解决在数据融合中存在的冲突问题,引入一种基于可信度、不确定度和重要度的数据融合权重确定方法,通过融合多来源的测试性信息得到舰炮制导弹药测试性指标评估结果。实例表明,所提方法能充分利用研制阶段收集的多来源测试性信息,有效利用主观不确定性信息,且减少数据冲突问题,可提高舰炮制导弹药测试性指标评估的可靠性。

主成分分析和灰色模型组合的身管多点烧蚀磨损量预测

身管是火炮类武器的关键零件,对其烧蚀磨损量进行预测,有助于保持火炮作战效能。针对火炮身管沿轴向各点烧蚀磨损量需分别建立数学模型进行预测问题,提出一种组合烧蚀磨损量预测方法。采用主成分分析(principal component analysis,PCA)方法对身管多点烧蚀磨损量进行数据空间降维,提取反映烧蚀磨损量变化的主成分,利用灰色模型对主成分进行多步预测,通过PCA逆运算获得身管内膛多点烧蚀磨损量预测值。结果表明,在历史数据较少的条件下,通过选择合适的预测步数可获得较为准确的预测值,为身管内膛多点烧蚀磨损量的预测提供了一种新的有效途径。

基于射击时机的坦克射击门分析及改进

针对坦克的射击门控制逻辑,分析现有射击门在坦克高速行进条件下在射击时机判断上的不足,提出基于预测机制的射击门改进方法,该射击门在考虑射击时延和炮口切向速度影响的情况下,去除了身管必须满足进入简单射击门的角度约束,可更大限度地把握有效射击时机,数字仿真结果验证了改进射击门的优越性。

电磁发射用直线电机及其控制技术综述

电磁发射用直线电机是电磁发射系统的核心执行机构,为电磁发射提供驱动磁场和加速通道。近十年来,电磁发射用直线电机及其控制技术日趋成为直线电机领域较为热点的研究方向。该文归纳了电磁发射用直线电机的特点和关键技术,综述了电磁发射用直线电机及其控制技术的研究现状,探讨了电磁发射用直线电机的发展趋势和应用前景,旨在为电磁发射用直线电机的后续研究提供方向引导。

枪管用环保镀层摩擦行为研究

传统枪管内膛表面采用的六价铬镀层,高温耐磨性好,但对环境污染严重。为开发环保镀层,采用超景深三维显微镜、扫描电子显微镜表征了室温和高温(400℃)摩擦磨损试样,对比分析了六价铬、三价铬、钴-镍和镍-钨四种电镀层的磨损特征。研究结果表明:在500℃定性回火后,三价铬、镍-钨、六价铬和钴-镍镀层硬度依次递减,与六价铬层相比,三价铬层脆性大,镍-钨和钴-镍镀层韧性高;室温下与H62黄铜对摩后,六价铬和三价铬镀层摩擦程度较轻,钴-镍和镍-钨镀层呈现明显粘着特征,二者摩擦系数高于两种铬层;400℃下与08Al钢对摩后,六价铬呈粘着磨损特征,摩擦程度较大;三价铬层摩擦系数相对较高;镍-钨镀层呈磨粒磨损特征,摩擦系数与六价铬接近,摩擦程度相对较轻。

基于身管应变的小口径火炮弹丸速度测试方法

针对传统火炮弹丸速度测试方法中存在难以获取整条速度曲线、易受环境影响、体积庞大、成本较高、操作复杂等问题,提出了一种基于身管应变的小口径火炮弹丸速度测试方法。基于30 mm口径火炮设计了应变测试仪,实现身管外壁应变测试。根据厚壁圆筒理论计算得出火炮膛压曲线,通过弹底压力解算模型得出弹底压力曲线,与弹载存储测试方法得到的弹底压力曲线进行对比。结合弹丸运动方程得出弹丸速度曲线,采用四阶龙格库塔算法建立弹丸速度仿真模型,将应变测试、弹载存储测试得到的弹丸速度曲线与仿真曲线进行对比。结果表明:应变测试、弹载存储测试与仿真弹丸速度曲线趋势基本吻合,最大速度误差分别为1.1%和0.5%,验证了应变测试方法的可行性,为小口径火炮弹丸测速开辟了新途径。

武器装备轻量化结构正向设计方法及应用

为满足武器装备轻量化的迫切需求,提升装备结构优化设计水平,提出了一种代理模型辅助多目标优化的结构正向设计方法。按照从概念设计到参数优化设计的流程,通过优化信息交互和代理模型重构来实现结构多目标优化设计。以轻型车载高炮弹箱架优化设计为例,首先,根据拓扑优化获得的最佳传力路径,建立几何模型和有限元分析模型。其次,通过灵敏度分析缩减设计变量,建立以一阶模态频率和结构强度为约束、最小化质量和最大化刚度为目标的优化模型。然后,使用差分进化算法求解基于Kriging模型的多目标优化问题;在优化过程中,通过比较中间优化结果调整优化模型,并采用基于期望改进的填充样本策略重构代理模型。最后,兼顾结构轻量化和安全,筛选44组优化解中的3组优势方案与初始设计进行比较,结果显示:在满足弹箱架结构性能的前提下,重量分别可减轻31.2%、24.7%和21.8%;所提结构正向设计方法能够明显提升轻量化效果,也可为相关结构优化设计提供参考。

多重约束下民警公务用枪的行动逻辑

公务用枪中存在的问题反映出公安机关在社会治理中的困境。实证研究发现,民警公务用枪的心理与行为受到多重条件的约束。文化与舆论是最外围的软性约束,影响着公务用枪的正义感。法律法规是较外围的刚性约束,决定着公务用枪的合法感。组织氛围是较内围的显性约束,决定着公务用枪的支持感。素质与训练则是最内围的硬性约束,决定着公务用枪的效能感。四个维度的用枪心理影响着民警在警务实战中的行为倾向和行为表现。涉枪事件的应对和涉枪民警的处理,又将反作用于涉枪民警及其他民警的心理与行为。研究结果为民警不愿拿枪、不敢用枪、不会用枪等问题找到一种阐释框架。

炮膛间距对枢轨初始接触状态的影响分析

电磁轨道炮炮膛间距直接影响到发射过程中枢轨滑动电接触状态,尤其是起始段炮膛间距变化对电枢烧蚀具有较大影响,将炮膛等效成呈一定角度张开的两条直线,利用角平分线相关特性开展炮膛间距测量,根据炮膛间距实测数据,结合工程实际分析起始段炮膛变化形态并建立对应形态下的枢轨初始接触模型,分析了炮膛装配精度对枢轨初始接触性能的影响,分析结果表明起始段炮膛间距是造成电枢静态受力不均、枢轨接触面积及接触力非对称分布的主要原因,通过不同炮膛变化形态的静态接触试验,进一步验证了理论分析结果。通过分析炮膛间距对枢轨初始接触的影响作用,为枢轨匹配性设计提供理论依据。

筋膜枪与拉伸放松改善运动性肌肉疲劳的比较

背景:利用科技手段促进运动后肌肉疲劳恢复的方法逐渐增多,如振动泡沫轴、筋膜枪放松、超低温冷疗等,其中筋膜枪放松在实践中已广泛使用,但是目前国内外对于筋膜枪的研究还较少。目的:比较筋膜枪、拉伸、筋膜枪+拉伸3种放松方式对运动性肌肉疲劳恢复过程中肌肉状态、肌肉力量的影响,为3种方法的实践应用提供科学依据。方法:40名大学生随机分为对照组(10名)、拉伸组(10名)、筋膜枪组(10名)、筋膜枪+拉伸组(10名)。所有受试者完成每组15次的腿屈伸训练,强度为60%1 RM,进行10组运动性疲劳造模,随后分别采用仰卧休息、静态拉伸、筋膜枪放松、筋膜枪+拉伸放松进行干预,且在训练前、训练后即刻、放松后即刻、运动后24 h及48 h进行肌肉状态、肌肉力量指标测试。结果与结论:①放松后即刻对照组、拉伸组的肌肉张力、动态硬度显著高于训练前(P<0.01),筋膜枪、筋膜枪+拉伸组与训练前相比差异无显著性意义(P>0.05);②训练后24 h对照组、筋膜枪组的峰力矩显著低于训练前(P<0.01),拉伸组、筋膜枪+拉伸组24 h后与训练前比较差异无显著性意义(P>0.05);③结果说明,筋膜枪能够即刻有效改善运动性疲劳的肌肉状态,拉伸能够促进运动性疲劳后肌肉力量在24 h内得到有效恢复,筋膜枪与拉伸结合的放松手段能够实现两种效果的叠加。

基于生成对抗网络数据增强的舰炮可靠性分析

舰炮故障数据不足会导致其可靠性分析变得极其困难。为解决故障数据不足这一问题,采用生成式对抗网络(generative adversarial network,GAN)对故障样本进行数据增强。建立GAN数据增强深度神经网络的舰炮可靠性分析模型,并与原始数据进行可靠性分析获得的指标进行了对比。结果表明,利用GAN数据增强后的扩充样本得到的指数分布拟合精度及威布尔分布拟合精度分别提高了5.40%和11.90%,相较于原始数据有了显著提升。为实现舰炮故障数据可靠性分析提供了方法和思路。

15-15hs Max材料枪钻加工的钻削力和切屑分析

高氮奥氏体不锈钢15-15hs Max具有优秀的耐蚀性、良好的综合力学性能,但切削加工性差,属于一种难加工材料。以某石油钻探部件为研究对象,对15-15hs Max的加工特性进行分析,通过对15-15hs Max钻削过程的有限元仿真,分析其加工过程中的钻削力和切屑形态的变化。仿真结果表明:钻削力会随着钻入深度的增加而增加,当切削刃全部参与切削时钻削力达到稳定,加工过程中形成的切屑为向上弯曲的螺旋状切屑。在保证加工孔质量及加工效率条件下,得出了一组较为合理的钻削参数。

刑事案件射击残留物高光谱实验教学设计研究

枪击案件中,除了传统的枪支、弹头弹壳痕迹检验外,射击残留物的检验、弹道的检验也是至关重要的组成部分,是法庭科学检验的重要研究对象。传统的枪弹弹痕检查课程注重对弹头弹壳弹痕的讲解,并结合少量枪械结构和弹道的介绍,对于现场快速提取检验刑事案件、现场快速检查弹丸弹痕(目标物弹孔)十分重要,然而,实验课程中并没有将弹着点射击残留物的相关知识纳入其中。本文针对警校本科生的特点,创新性地提出对于枪弹痕迹检验课程实验教学模式的新探索,将现场勘验射击残留物的实验纳入课程,使教学内容形成科学完整的体系,同时采用虚拟现实教学手段克服该课程实践难的特点,以达到学以致用、服务实战的教学效果。

小型化Ka波段行波管快启电子枪研究

针对弹载环境中毫米波行波管快速启动要求,利用ANSYS软件模拟电子枪阴极施加热丝功率对阴极温度产生的影响,并通过电子枪温度试验,定量测定热丝功率和阴极温度的对应关系,验证温度对阴极发射的影响。在模拟和试验基础上,开展电子枪小型化结构设计,成功研制出小型化毫米波弹载行波管用电子枪,使其满足弹载环境15 s快启功能。