DNAN 基熔铸炸药成型过程数值仿真

为模拟DNAN 基熔铸炸药成型过程,采用结构网格计算流场和温度场、非结构网格计算应力场的方法,得到DNAN 基熔铸炸药冷却凝固时清晰的固液界面以及合理的缩孔缩松及热应力分布。通过对比研究,在一定模具和装药尺寸条件下,提出减少DNAN 基熔铸炸药装药缩孔缩松、降低热应力极值以及缩短凝固时间的优化方案,方案为模具上表面保温1 h,模具下表面30 益恒温水浴。     

机床底座ProCAST数值模拟及铸造工艺优化

中型灰铸铁机床底座铸造过程中,补缩不足使铸件厚大部分产生较大缩松缩孔,用Creo进行机床底座3D建模,通过3D打印制作分析模型;用ProCAST软件对充型与凝固过程进行多方案、多次有限元分析及仿真模拟.结果表明:铸件厚大部位易产生热节,冷却后产生缩松缩孔,用增加冒口与铺设冷铁等方案优化铸造工艺,使铸件自然补缩,最终实现自下而上的顺序凝固,有效避免产生较大热节,解决了铸件的缩松缩孔缺陷.     

成型工艺对2,4-二硝基苯甲醚基熔铸炸药装药质量的影响

为了提高2,4-二硝基苯甲醚（DNAN）基熔铸炸药的装药质量,采用压力浇铸与真空浇铸成型工艺,研究其对DNAN基熔铸炸药温度场、缩孔疏松、相对密度及抗拉强度的影响规律。结果表明：压力浇铸使DNAN基熔铸炸药凝固时间缩短,药柱内部缩孔疏松及气孔减少;当成型压力达到0.8 MPa时,DNAN/奥克托今（HMX）炸药相对密度和抗拉强度分别提高了6.4%、9.9%,药柱无裂纹;DNAN/黑索今（RDX）炸药的相对密度提高了2.7%,但抗拉强度降低了40.8%,同时药柱存在裂纹。真空浇铸对DNAN基熔铸炸药凝固过程温度场无影响,使药柱内部缩孔疏松及气孔减少;当真空度达到0.08 MPa时,DNAN/RDX炸药的相对密度及抗拉强度分别提高了2.0%、14.3%,药柱无裂纹。因此,为了获得高质量的熔铸炸药,DNAN/HMX炸药可采用压力浇铸;DNAN/RDX炸药可采用真空浇铸。     

半固态锌合金凝固过程数值模拟

以ZA9半固态锌合金为研究对象,研究其凝固过程温度变化及影响因素。应用Fluent软件建立锌铝合金自然对流下的凝固数学模型,获得在牛顿流体和非牛顿流体假设下自然对流液相体积分数的分布图。利用自行研制的半固态浆料凝固过程温度测试试验台,对制取的锌铝合金半固态浆料温度进行控制和记录,并对两种模型的凝固界面及试验获得的凝固过程温度场数据进行对比,验证了模拟结果的可靠性。     

熔黑梯炸药凝固过程的数值模拟与实验验证

为了解浇铸炸药的凝固过程,采用有限元法对熔黑梯炸药凝固过程中的温度场进行了模拟,并对凝固过程中可能产生的缩孔进行了预测.结果表明,熔黑梯炸药凝固过程中内外温差较大,中心位置附近的温度变化曲线在75 ℃左右存在拐点,在药柱中间位置将出现缩孔和缩松.另外还采用热电偶对熔黑梯炸药凝固过程中的温度变化进行了测试,采用工业CT对固化后的熔黑梯药柱内部质量进行了检测,并将数值模拟结果和实验测试结果进行了对比,结果表明有限元方法可以对熔黑梯炸药凝固过程进行有效模拟.     

2,4-二硝基苯甲醚基熔铸炸药慢速烤燃过程传热特征分析

为探究2,4-二硝基苯甲醚基熔铸炸药慢速烤燃过程的内部传热特征,设计了3组试验装置并进行烤燃试验。通过试验获得了炸药内部各测点在1 K/min热刺激下的温度变化曲线,其相变温度为73 ℃,响应温度为205 ℃,响应后均表现为不完全燃烧反应;结合响应结果判断出点火点位于弹体上部;系统地描述了炸药从固相到液相再到响应的内部温度变化过程。通过数值模拟观察了炸药相变的整个过程,对炸药受热时内部温度场变化进一步分析后发现：固相时炸药内部温度场为同心类椭圆状分布,液相时内部温度场为类层状分布;炸药相变后内部存在自然对流,对流是影响炸药点火点位置分布的主要因素。     

TNT炸药熔铸结晶成型过程μCT实验研究

利用微焦点工业CT(μCT)对TNT炸药熔铸结晶成型过程进行了在线监测试验研究,获得了成型过程TNT炸药结晶与成型质量的三维细观结构及其分布的演化特征与规律.结果表明: 炸药结晶凝固速度在初始阶段最快,随后逐渐降低; 在凝固过程中缩孔存在逐渐增大直至稳定、交联的现象; 靠近侧壁和底部部位的缩孔少、CT值高,相应密度值也高.在保温、不补缩状态下熔态TNT浇铸凝固后的细小缩孔率为7.13%,集中缩孔与细小缩孔体积之和大于所浇铸悬浮液体积的20%; 药柱下部与中下部直至中部截面的线密度差约1.5%～8%,表层与浅表层直至靠近中心部位的线密度差则达5%～18%.     

熔铸炸药凝固过程内部温度和缺陷的数值仿真

为预估熔铸炸药凝固过程中装药内部温度场的变化和出现缺陷的位置,采用有限元程序ProCAST对RHT炸药的凝固过程进行数值模拟。以熔铸炸药RHT的凝固过程为研究对象,计算出装药内部的温度场分布,预测装药内部形成缩孔和缩松的位置,并与试验结果进行对比验证。结果表明:ProCAST程序能够准确计算出熔铸炸药凝固时内部缺陷的位置,可以用于炸药熔铸工艺的仿真设计。     

铸造成型局部加压补缩控制系统设计和应用实例

在现有铸造技术的基础上采用局部延时加压补缩工艺,即对进入铸造模具型腔内的接近模具热节处的液态或半固态金属在完全凝固之前,局部施加较高的机械压力,使铸件热节处的周围尽量形成补缩通道,以提高凝固过程中补缩效果,然后凝固成型,完成整个铸造过程。该工艺可有效提高铸件热节处金属组织致密度和性能,克服现有铸造技术在铸件制造中厚大部位易产生缩孔和缩松缺陷的关键问题,并可以在铸件工艺设计中省略或部分省略冒口设置,提高了金属材料的利用率。     

铸钢件凝固过程热裂纹数值模拟及预测

根据铸钢件凝固过程三维温度场模拟和热裂纹形成的理论分析,提出了一种考虑凝固速度,补缩能力因素的热裂纹预测判据。在凝固过程温度场数值模拟的基础上,利用预测判据对实验铸件和实际铸件的热裂进行了预测,预测与实际结果吻合。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Open Rule-setting System Applied to Conceptual Design of Engines

Open rule-setting method advanced in this paper concentrates on providing designers of engines with a convenient way to express their design innovations and develop the expected prototypes in the early CAD stage, and constitute effective models for the following analysis process of CAE and CAPP. The problems arisen in the process of conceptual design with the traditional experience-based development method are analyzed. Based on those analyses, open rule-setting method is presented and some associated technical problems are discussed. The functional framework of open rule-setting system was built as software engineering methods. The speciality of the engine product as a kind of complex product and the requirement of the engine product based on its structural particularity to rule-setting system are considered carefully. A demonstration is supplied to illustrate how the open rule-setting method enhances the efficiency and quality of the engine conceptual design.     

Research on Linux Network Device Driver

By analyzing the working principle of Linux network device driver, discussing the Linux network driver structure and its key technologies, the general network driver structure and its design methodologies in Linux system are summarized. Through modifying the network device driver of Linux device driver 3rd version snull, c and improving the COW technology, the Zero-Copy technology in Linux （kernel version 2.6.11 ） is implemented. In the end, the success test tells us that the thorough analysis of network device driver is the foundation of many applications, and it also provides a certain improvement to a lot of real applications, even to military application development.     

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.     

Experimental Study on the Small Flyer Initiating Behavior of Fine-grained Explosives

The initiating behavior of fine-grained explosives by small flyer is studied. The diameter of small flyer in this device is 1 ram. The test results indicate that the granularity of explosives has great effect on its flyer initiating sensitivity.The flyer initiating sensitivity of the fine-grained explosives is higher and the critical initiating energy is lower than that of common explosives. For common explosive, the flyer initiating sensitivity increases as the density is reduced. But for the fine-grained explosive, the test results are exactly opposite.     

Algorithm for Multi-laser-target Tracking Based on Clustering Fusion

Multi-laser-target tracking is an important subject in the field of signal processing of laser warners. A clustering method is applied to the measurement of laser warner, and the space-time fusion for measurements in the same cluster is accomplished. Real-time tracking of multi-laser-target and real-time picking of multi-laser-signal are introduced using data fusion of the measurements. A prototype device of the algorithm is built up. The results of experiments show that the algorithm is very effective.     

Influence of Installing Error on the Surface Shape Precision of the Axial Symmetry Aspheric Workpiece in Lapping

A method to calculate the surface shape error, which is caused by the installing error between the workpiece and the lapping tool in the process of form lapping, is proposed. The mathematical model which the installing translation error influences on the workpiece surface shape error is established. The changing rule of the error is simulated through the calculating example of the paraboloid workpiece. The results indicate that the surface shape error of the workpiece is increasing with the increase of the installing translation error, it is also increasing gradually along the center point of the curve surface to the edge, and the influence is severer to the curve surface with great curvature than that of the small curvature when the translation error is the same.     

Experimental Research on Output Performances of Giant Magnetostrictive Actuator

The paper introduces the performances of magnetostrictive actuators and its applications, discusses the design methods for the structure and internal magnetic circuit of a giant magnetostrictive actuator, and makes tests on the output displacement and force characteristics for an actuator using homemade magnetostrictive material. The experimental result shows that the actuator has satisfactory output precisions and ranges in transient and stable states, and can be used in lowfrequency vibration control system of precise equipment.     

Robust Graded Sliding Mode Tracking Control for Low Speed Spinning Ballistic Missiles

The nonlinear dynamic model of spinning ballistic missiles is established during the first boosting phase of the missile. Based on the conventional backstepping sliding mode control and the assumption of a two time-scale separation of missile dynamics, a graded sliding mode controller is designed with two sub-sliding surfaces which have invariability to external disturbances and parameter perturbations, and a matrix which comprises three first order low pass filters is introduced to prevent ＂explosion of terms＂. Owing to the upper bounds of the uncertainties are difficult to obtain in advance, adaptive laws are introduced to estimate the values of the uncertainties in real-time. Eventually, the numerical simulation results given to show the proposed controller can ensure the steady flight of missiles.