Numerical simulation of detonation of an explosive atmosphere of liquefiedpetroleum gas in a confined space

The detonation of an explosive atmosphere from liquefied petroleum gas disseminated in air in a confined space is studied using numerical modeling with software product ANSYS AUTODYN. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Analysis on the resistive force in penetration of a rigid projectile

According to the dimensionless formulae of DOP （depth of penetration） of a rigid projectile into different targets, the resistive force which a target exerts on the projectile during the penetration of rigid projectile is theoretically analyzed. In particular, the threshold Vc of impact velocity applicable for the assumption of constant resistive force is formulated through impulse analysis. The various values of Vc corresponding to different pairs of projectile-target are calculated, and the consistency of the relative test data and numerical results is observed. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Single channel source separation of radar fuze mixed signal based on phasedifference analysis

A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze. This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals, solve the candidate data set by the mixing coefficients and signal analytical form, and resolve the problem of vector ambiguity by analyzing the phase differences. The signal separation is realized by exchanging data of the solutions. The waveform similarity coefficients are calculated, and the timeefrequency distributions of separated signals are analyzed. The results show that the proposed method is effective. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Nitrogen analogs of TEX e A computational studyLemi

TEX, a well-known nitramine type explosive, has been subjected to centric perturbations by replacing its etheric （acetal） oxygens withnitrogen atoms one by one. The structural features, stabilities and IR and UV-VIS spectra of new structures formed are investigated. For thispurpose, density functional theory has been employed at the B3LYP/6-31G （d,p） and B3LYP/6-311G（d） levels. In general the calculationsrevealed that the oxygenenitrogen replacement resulted in more energetic but less sensitive structures than TEX.Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Influence of high frequency pulse on electrode wear in micro-EDM

An electromagnetic coupling mathematical model is established by finite element method and is verified by the contrastive experiments of copper matrix NieTiN cylindrical coating electrode, copper electrode and Cu50W electrode. The wear mechanism of NieTiN/Cu composite electrode in the case of high-frequency pulse current is studied, and the influence of the fluctuation frequency of discharge current on electrode wear in micro-EDM is found out. Compared with the electrode made from homogeneous material, the high frequency electromagnetic properties of NieTiN composite layer can be used effectively to inhibit the effect of high frequency pulse on the electrode and improve the distribution trend of current density. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Indirect robust control of agile missile via Theta-D technique

An agile missile with tail fins and pulse thrusters has continuous and discontinuous control inputs. This brings certain difficulty to the autopilot design and stability analysis. Indirect robust control via Theta-D technique is employed to handle this problem. An acceleration tracking system is formulated based on the nonlinear dynamics of agile missile. Considering the dynamics of actuators, there is an error between actual input and computed input. A robust control problem is formed by treating the error as input uncertainty. The robust control is equivalent to a nonlinear quadratic optimal control of the nominal system with a modified performance index including uncertainty bound. Theta-D technique is applied to solve the nonlinear optimal control problem to obtain the final control law. Numerical results show the effectiveness and robustness of the proposed strategy. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Analysis of equivalent antenna based on FDTD method

An equivalent microstrip antenna used in radio proximity fuse is presented. The design of this antenna is based on multilayer multipermittivity dielectric substrate which is analyzed by finite difference time domain （FDTD） method. Equivalent iterative formula is modified in the condition of cylindrical coordinate system. The mixed substrate which contains two kinds of media （one of them is air）takes the place of original single substrate. The results of equivalent antenna simulation show that the resonant frequency of equivalent antenna is similar to that of the original antenna. The validity of analysis can be validated by means of antenna resonant frequency formula. Two antennas have same radiation pattern and similar gain. This method can be used to reduce the weight of antenna, which is significant to the design of missile-borne antenna. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Analysis of parameter estimation using the sampling-type algorithm ofdiscrete fractional Fourier transform

Parameter estimation is analyzed using two kinds of common sampling-type DFRFT （discrete fractional Fourier transform） algorithm. Amodel of parameter estimation is established. The factors which influence estimation accuracy are analyzed. And the simulation is made to verifythe conclusions. From the theoretic analysis and simulation verification, it can be drawn that, for the estimation of chirp-rate and initial frequency,Pei＇s method [10] is more suitable if the absolute value of chirp-rate is small relatively; Ozaktas＇ method [9] is more suitable if theabsolute value of chirp-rate is large relatively; and the two methods are both workable if the absolute value of chirp-rate is moderate. The scopeof moderate chirp-rate can be approximately determined as [40 Hz/s, 110 Hz/s].Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Investigation on the foaming behaviors of NC-based gun propellants

To prepare the porous NC-based （nitrocellulose-based） gun propellants, the batch foaming process of using supercritical CO2 as the physical blowing agent is used. The solubilities of CO2 in the single-base propellants and TEGDN （trimethyleneglycol dinitrate） propellants are measured by the gravimetric method, and SEM （scanning electron microscope） is used to observe the morphology of foamed propellants. The result shows that a large amount of CO2 could be dissolved in NC-based propellants. The experimental results also reveal that the energetic plasticizer TEGDN exerts an important influence on the pore structure. The triaxial tensile failure mechanism for solid-state nucleation is used to explain the nucleation of NC-based propellants in the solid state. Since some specific foaming behaviors of NC-based propellants can not be explained by the failure mechanism, a solid-state nucleation mechanism which revises the triaxial tensile failure mechanism is proposed and discussed. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Interaction and Compatibility Between DAAzF and Some Energetic Materials

The interaction and compatibility between diaminoazofuraz （DAAzF） and some energetic materials are studied by using pressure differential scanning calorimetry （DSC） method. The energetic materials include cyclotetramethylenetetranitramine （HMX）, cyclotrimethylenetrinitramine （RDX）, nitrocellulose （NC）, nitroglycerine （NG）, 125/100--NC/NG mixture （NC ＋ NG）, N-nitrodihydroxyethylaminedinitrate （DINA）, aluminum powder （A1）, and 3,4-dinitrofurzanfuroxan （DNTF）. The results show that there are obvious interactions between DAAzF and DNTF, DINA, HMX or RDX, while weak interactions between DAAzF and NC, NG, NC ＋ NG or A1. According to the evaluated standard of compatibility, the binary systems of DAAzF with NC, NG, NC ~ NG and A1 are compatible, the binary system of it with RDX is slightly sensitive, the binary systems of it with HMX and DINA are sensitive, and the binary system of it with DNTF is hazardous. Copyright 2013, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Combined proportional navigation law for interception of high-speed targets

A new proportional navigation （PN） guidance law, called combined proportional navigation （CPN）, is proposed. The guidance law is designed to intercept high-speed targets, which is a common case for ballistic targets. The range of target-to-interceptor speed ratio during target interception is derived when guidance laws are applied in high-speed targets interception, and the effectiveness of negative navigation ratio in the PN-based guidance law is proven analytically in some lemmas .Based on the lemmas, the lateral acceleration command of CPN is defined, and the solution to the appearance of singularity in time-varying navigation ratio is given. The simulation results show that CPN can determine headon engagement （as PN） or tail-chase engagement （as RPN） through initial path angle compared with PN and retro proportional navigation （RPN）, and can adjust the value of navigation ratio for head-on engagement or tail-chase engagement. Therefore, the capture region of CPN is larger than that of other guidance laws using PN-based methods. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

《弹道学报》征稿简则

正《弹道学报》是由中国科协主管、中国兵工学会主办、南京理工大学承办的国内外公开发行的学术期刊,创刊于1989年,主要刊载弹道学领域中内弹道学、中间弹道学、外弹道学、水中弹道学、终点弹道学、创伤弹道学、实验弹道学、发射动力学、空气动力学、飞行力学、导弹控制系统、弹道系统综合与分析、弹道测试技术,以及有关飞行物体运动规律等方面的最新研究成果的学术论文。鉴于《弹道学报》在国内外的重要影响,《弹道学报》成为国内外许多重要数据库、文摘刊物和检索机构的收录刊源。在北京大学出版社出版的北大图书馆2014版、2017版(最新版)《中文核心期刊要目总览》武器工业类核心期刊中《弹道学报》均排名第二。收录《弹道学报》的国内外重要数据库、文摘刊物及检索机构包括:(1) Elsevier二次文献数据库(Scoups,Geobase,     

Numerical simulation of base flow with hot base bleed for two jet models

In order to improve the benefits of base bleed in base flow field, the base flow with hot base bleed for two jet models is studied. Twodimensional axisymmetric NaviereStokes equations are computed by using a finite volume scheme. The base flow of a cylinder afterbody with base bleed is simulated. The simulation results are validated with the experimental data, and the experimental results are well reproduced. On this basis, the base flow fields with base bleed for a circular jet model and an annulus jet model are investigated by selecting the injection temperature from 830 K to 2200 K. The results show that the base pressure of the annular jet model is higher than that of the circular jet model with the changes of the injection parameter and the injection temperature. For the circular jet model, the hot gases are concentrated in the vicinity of the base. For the annular jet model, the bleed gases flow into the shear layer directly so that the hot gases are concentrated in the shear layer. The latter temperature distribution is better for the increase of base pressure. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Optimization of process parameters of the activated tungsten inert gaswelding for aspect ratio of UNS S32205 duplex stainless steel welds

The activated TIG （ATIG） welding process mainly focuses on increasing the depth of penetration and the reduction in the width of weld bead has not been paid much attention. The shape of a weld in terms of its width-to-depth ratio known as aspect ratio has a marked influence on its solidification cracking tendency. The major influencing ATIG welding parameters, such as electrode gap, travel speed, current and voltage, that aid in controlling the aspect ratio of DSS joints, must be optimized to obtain desirable aspect ratio for DSS joints. Hence in this study, the above parameters of ATIG welding for aspect ratio of ASTM/UNS S32205 DSS welds are optimized by using Taguchi orthogonal array （OA） experimental design and other statistical tools such as Analysis of Variance （ANOVA） and Pooled ANOVA techniques. The optimum process parameters are found to be 1 mm electrode gap, 130 mm/min travel speed, 140 A current and 12 V voltage. The aspect ratio and the ferrite content for the DSS joints fabricated using the optimized ATIG parameters are found to be well within the acceptable range and there is no macroscopically evident solidification cracking. Copyright ？ 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

《弹道学报》征稿简则

正《弹道学报》是由中国科协主管、中国兵工学会主办、南京理工大学承办的国内外公开发行的学术期刊,创刊于1989年,主要刊载弹道学领域中内弹道学、中间弹道学、外弹道学、水中弹道学、终点弹道学、创伤弹道学、实验弹道学、发射动力学、空气动力学、飞行力学、导弹控制系统、弹道系统综合与分析、弹道测试技术,以及有关飞行物体运动规律等方面的最新研究成果的学术论文。鉴于《弹道学报》在国内外的重要影响,《弹道学报》成为国内外许多重要数据库、文摘刊物和检索机构的收录刊源。在北京大学出版社出版的北大图书馆2014版、2017版(最新版)《中文核心期刊要目总览》武器工业类核心期刊中《弹道学报》均排名第二。收录《弹道学报》的国内外重要数据库、文摘刊物及检索机构包括:(1) Elsevier二次文献数据库(Scoups,Geobase,CPX,Embase);(2)美国《剑桥科学文摘》(CSA);(3)《日本科学技术振兴机构(中国)数据库》(JSTChina);(4)美国《乌利希期     

Neural network modeling to evaluate the dynamic flow stress of highstrength armor steels under high strain rate compression

An artificial neural network （ANN） constitutive model is developed for high strength armor steel tempered at 500
C, 600
C and 650
Cbased on high strain rate data generated from split Hopkinson pressure bar （SHPB） experiments. A new neural network configuration consistingof both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered asinputs, whereas flow stress is taken as output of the neural network. A comparative study on JohnsoneCook （JeC） model and neural networkmodel is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and temperingtemperatures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB, over a range of temperingtemperatures （500e650
C）, strains （0.05e0.2） and strain rates （1000e5500/s） are employed to formulate JeC model to predict the high strainrate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the highstrain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient （R） andaverage absolute relative error （AARE）. R and AARE for the JeC model are found to be 0.7461 and 27.624%, respectively, while R and AAREfor the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with theexperimental data for all tempering temperatures.Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

缅甸特种部队的“由后捕俘”制敌术(上)

踹膝勒颈 采取这一招式,首先隐蔽接近目标,当距目标约五六步远时,迅速跃至其背后,右脚抬起与其膝窝同高,左臂弯曲,右手掌心向下伸至目标右肩上方;紧接着以右脚外侧猛踹目标的膝窝,趁其后仰下蹲之际,右手紧贴其颈部将右小臂插入其颌下,以手腕骨卡压其喉;然后左手抓拉右手腕,双手协力后拉勒其颈部的同时,右脚落地,肩顶其头,胯顶其腰,将其制服. 这个招式的要领是:接近目标时要隐蔽,跃起要快,踹、勒要协调一致.     

全保护型护手/高精度卡宾枪——M10卡宾枪

美军制式M4卡宾枪存在的一个问题是,其护手只包裹住枪管的一半长度,造成士兵不易携行,特别是持续射击后转移阵地时,因枪管滚烫,士兵只能握持有限的护手部分。如今,这个问题在CMMG公司的手中得到了解决,当然,在解决这个问题时,公司还重新设计了抛壳问题,并且在各组件的精密配合下,射击精度也获得提升,堪比高精度狙击步枪——     

专为美国市场打造:MR556A1步枪

经过努力,HK416的美国民用版终于改造成功,命名为MR556A1步枪.MR556A1仍然采用5.56mm口径,空枪质量4.1kg,采用伸缩式枪托,枪托伸展时全枪长957mm,枪托收回时全枪长861mm,枪管长419mm,瞄准基线长371mm.由于受美国武器法规的限制,该枪的枪管和下机匣必须在美国本土制作,为此HK公司在佐治亚州哥伦布市建立生产线,从德国进口枪管半成品、枪机组件、护手和发射控制组件等,在此进行进一步加工处理,并且制作出机匣组件,使其最终拥有美国本土武器的合法身份.     

智能系统中行驶路径的查找方法

智能系统中,寻找行驶路径分为对静止物和运动物的绕行.避开静止物时,从起点到终点拉一直线,遇到障碍物即顺时针绕行,碰到直线后再沿直线行驶,可到达终点.避开运动物是,相遇时先等待,若运动物挪开,仍按原路径前进;超时,则比较其优先级,低者等待,高者按避开静止物方法重新计算行走路径.