装甲兵作战仿真系统信息存储与回放

在分析DIS信息结构和数据库的基础上,对基于DIS的装甲兵作战仿真系统信息存储与回放进行了研究,并将其应用于装甲兵作战仿真实验室的建设中,收到了良好的效果.     

“打倒军阀”语境下的唐继尧之死

北伐时期,"打倒军阀"成为革命动员的最重要口号和战争进行的最主要目标。在此代际更替的关键时刻,滇系军阀头目唐继尧离世,其死后的寂寞寥落与生前的轰轰烈烈形成大反差,不由得使人感叹:生逢其时,而死不逢时,其故去时正好是人生曲线的最低点,是世态炎凉的最低潮。前时叱咤风云的人物,若不趋新进取,势必被历史迅速淘汰。透过时论,回归语境,感受氛围,给我们考察时代转换之际曾经的要角是如何被世人所迅速"淡忘"、中国近代第一代军阀是如何退出历史舞台提供了别样视角。     

国民党“临全大会”与战时党政体制的建构

1938年,国民党在武汉召开"临全大会",通过了设立总裁制、组织非常时期国民参政会和抗战建国纲领等议案,逐步建立了以蒋介石为党政军最高领袖、以国防最高委员会为决策和执行机关、以国民参政会为战时"民意机关"的战时党政体制。这一战时体制的建构,既造成了国家权力高度集中与个人独裁,又使各党派获得了建言议政的机会。两者互为矛盾,却又共存发展。     

大数据技术专题讲座(二) 第3讲 面向大数据处理的MapReduce优化技术

随着大数据时代的到来,大规模数据的处理技术研究层出不穷。MapReduce计算框架的出现,暂时缓解了大数据的处理难题。虽然MapReduce能够实现大规模数据(通常为PB级甚至EB级)的高效并行处理,但在企业应用环境中,MapReduce底层架构和处理模式上的缺陷逐渐暴露出来,造成了处理效率、执行性能上的一些瓶颈。针对这些不足,结合企业实际处理需求,产生了针对MapReduce的各个方面的优化研究。文中首先阐述了MapReduce的编程模型和实现机制,然后总结了对MapReduce作业调度、实时处理、架构和服务等方面的优化研究,最后对MapReduce各种优化技术进行了总结和展望。     

Controllable combustion behaviors of the laser-controlled solid propellant

Microsatellites have been widely applied in the fields of communication,remote sensing,navigation and science exploration due to its characteristics of low cost,flexible launch mode and short development period.However,conventional solid-propellant have difficulties in starting and interrupting combustion because combustion is autonomously sustained after ignition.Herein,we proposed a new type of solid-propellant named laser-controlled solid propellant,which is sensitive to laser irradiation and can be started or interrupted by switching on/off the continuous wave laser.To demonstrate the feasibility and investigate the controllable combustion behaviors under different laser on/off conditions,the combus-tion parameters including burning rate,ignition delay time and platform pressure were tested using pressure sensor,high-speed camera and thermographic camera.The results showed that the increase of laser-on or laser-off duration both will lead to the decrease of propellant combustion performance during re-ignition and re-combustion process.This is mainly attributed to the laser attenuation caused by the accumulation of combustion residue and the change of chamber ambient temperature.Simultaneously,the multiple ignition tests revealed that the increased chamber ambient temperature after combustion can make up for the energy loss of laser attenuation and expansion of chamber cavity.However,the laser-controlled combustion performance of solid propellant displayed a decrease trend with the addi-tion of ignition times.Nevertheless,the results still exhibited good laser-controlled agility of laser-controlled solid propellant and manifested its inspiring potential in many aspects of space missions.     

导弹遥测系统应用CAN总线技术的探讨

CAN(Controller Area Net)总线技术,是主要用于各种过程检测和控制的一种现场总线。CAN总线采用双线串行通讯方式,具有很强的检错和抗干扰能力,最高通讯速率可达1Mbit/s,最大通讯距离为10000m。CAN具有优先权和仲裁功能,多个具有CAN总线控制器的带有CPU的仪器连接到CAN总线上,可以形成多主机的局部控制网。本文主要介绍CAN总线技术在导弹遥测系统中的应用展望。     

Bionic stab-resistant body armor based on triangular pyramid structure

A stab-resistant substrate was designed and realized with a triangular pyramidal structure, inspired by the biological armor model in nature. The stab-resistance behavior and dynamic response mechanisms were studied through numerical simulation and experimental testing of a knife impacting a substrate, and an optimal structural design was obtained accordingly, with a tilted angle of 22.5° and optimal thickness of 1.2 mm. It was shown that the triangular pyramidal structure generated twice the internal energy of the knife than the flat substrate due to the dispersing effect of the structure. The force parallel to the inclination caused a significant scratch on the substrate surface, while the force perpendicular caused obvious substrate deformation. A new riveting method was used to form the total layer, which passed the GA 68—2008 standard. The stab-resistant clothing coupled with the reduced wearing burden could provide effective protection and avoid fatal injuries on security personnel working in dangerous environments. The method provided may enlighten the future design and manufacturing of stab-resistant clothing.     

Partial penetration of annular grooved projectiles impacting ductile metal targets

Changing and optimizing the projectile nose shape is an important way to achieve specific ballistic performance. One special ballistic performance is the embedding effect, which can achieve a delayed high-explosive reaction on the target surface. This embedding effect includes a rebound phase that is significantly different from the traditional penetration process. To better study embedment behavior, this study proposed a novel nose shape called an annular grooved projectile and defined its interaction process with the ductile metal plate as partial penetration. Specifically, we conducted a series of low-velocity-ballistic tests in which these steel projectiles were used to strike 16-mm-thick target plates made with 2024-O aluminum alloy. We observed the dynamic evolution characteristics of this aluminum alloy near the impact craters and analyzed these characteristics by corresponding cross-sectional views and numerical simulations. The results indicated that the penetration resistance had a brief decrease that was influenced by its groove structure, but then it increased significantly-that is, the fluctuation of penetration resistance was affected by the irregular nose shape. Moreover, we visualized the distribution of the material in the groove and its inflow process through the rheology lines in microscopic tests and the highlighted mesh lines in simulations. The combination of these phenomena revealed the embed-ment mechanism of the annular grooved projectile and optimized the design of the groove shape to achieve a more firm embedment performance. The embedment was achieved primarily by the target material filled in the groove structure. Therefore, preventing the shear failure that occurred on the filling material was key to achieving this embedding effect.     

Experimental investigation on enhanced damage to fuel tanks by reactive projectiles impact

Enhanced damage to the full-filled fuel tank,impacted by the cold pressed and sintered PTFE/AL/W reactive material projectile(RMP)with a density of 7.8 g/cm3,is investigated experimentally and theoretically.The fuel tank is a rectangular structure,welded by six pieces of 2024 aluminum plate with a thickness of 6 mm,and filled with RP-3 aviation kerosene.Experimental results show that the kerosene is ignited by the RMP impact at a velocity above 1062 m/s,and a novel interior ignition phenomenon which is closely related to the rupture effect of the fuel tank is observed.However,the traditional steel projectile with the same mass and dimension requires a velocity up to 1649 m/s to ignite the kerosene.Based on the experimental results,the radial pressure field is considered to be the main reason for the shear failure of weld.For mechanism considerations,the chemical energy released by the RMP enhances the hydrodynamic ram(HRAM)effect and provides additional ignition sources inside the fuel tank,thereby enhancing both rupture and ignition effects.Moreover,to further understand the enhanced ignition effect of RMP,the reactive debris temperature inside the kerosene is analyzed theoretically.The initiated reactive debris with high temperature provides effective interior ignition sources to ignite the kerosene,resulting in the enhanced ignition of the kerosene.     

Robust cubature Kalman filter method for the nonlinear alignment of SINS

Nonlinear initial alignment is a significant research topic for strapdown inertial navigation system(SINS).Cubature Kalman filter(CKF)is a popular tool for nonlinear initial alignment.Standard CKF assumes that the statics of the observation noise are pre-given before the filtering process.Therefore,any unpredicted outliers in observation noise will decrease the stability of the filter.In view of this problem,improved CKF method with robustness is proposed.Multiple fading factors are introduced to rescale the obser-vation noise covariance.Then the update stage of the filter can be autonomously tuned,and if there are outliers exist in the observations,the update should be less weighted.Under the Gaussian assumption of KF,the Mahalanobis distance of the innovation vector is supposed to be Chi-square distributed.Therefore a judging index based on Chi-square test is designed to detect the noise outliers,determining whether the fading tune are required.The proposed method is applied in the nonlinear alignment of SINS,and vehicle experiment proves the effective of the proposed method.