惯性定向定位/导航技术及发展概况

阐述了惯性导航、陀螺罗经定向工作原理和捷联惯性导航的计算问题,以及GPS的有关情况。最后,预测捷联惯性系统和GPS 组合将成为航空、航海和陆地车辆导航定位的主要装置。     

圆锥壳方程的二次渐近解

本文由旋转壳的一对二阶常微分方程得出圆锥壳的复变量方程,利用渐近积分法推导出方程的一次近似解和二次近似解。二次近似解达到薄壳理论所具有的精度,一次近似解也具有足够精度。对于所取算例,本文解的计算结果与已有的Kelvin函数解的结果符合良好。但本文解为有限形式的简单表达式,便于计算应用。     

建立不工作失效率理论预测模型的具体方法

本文介绍了建立不工作失效率理论预测模型的具体方法和途径,提出检验数据是否可用的五条标准,并讨论了模型建立过程中应注意的几个特殊因素。     

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.     

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.     

重评北洋时期冯玉祥治军

冯玉祥是从北洋军中普通一兵“起家”的高级将领,又是反抗北洋军阀“发家”的有代表性的军人。笔者认为冯玉祥在北洋时期的治军颇具特点,是对北洋军的“变异”。本文探讨其“变异”的原因,并指出冯玉祥治军存在着家长制的弊端。     

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。     

“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。     

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.