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.     

均匀面积映射及其在均匀纹理映射中的应用

为形成一个具有更小拉伸的网格参数化映射,在三角形网格面片面积均匀分布的情况下,采用分两步走的均匀面积映射法。通过均质化参数域里的三角形面积,用均匀或不均匀方式有效地降低了采样稀疏问题的影响,避免了传统方法中矩阵奇异值的计算。对三角形网格,先进行均值协调参数化,然后通过一个凸组合让参数域更加均匀,得到一个拉伸较低、面积更加均匀的三角形分布,从而可以更好地取样且适合于纹理映射。通过实验和对比,可以证明在均匀纹理映射方面,均匀面积映射法比保角映射法和等积投影映射法都有明显的提高。     

考虑有损伤测量条件下的设备剩余寿命的建模分析

在有损测量的情况下,仅从退化数据本身出发所建的模型不能反映设备的真实退化过程.尤其在测量导致的设备性能退化量不可忽略时,不考虑测量耗损量将不能有效进行预测和评估.为解决这个问题,首先基于维纳过程建立有损测量的设备退化过程,进一步给出了相应模型的参数估计方法和基于贝叶斯理论的设备剩余寿命的实时更新方法,最后通过一个仿真示...     

灭火救援过程中撤离战术应用研究

结合公安消防部队灭火救援工作实际,对照以往消防部队在灭火救援过程中对撤离战术应用的情况,指出了撤离战术应用需要提高思想认识,加强战术训练,科学预测风险,准确判断时机和合理选择撤离方式,并阐述了在灭火救援过程撤离战术的应用方法。     

基于结构随机跳变系统的制导误差预测

针对空中目标作大机动时导弹制导误差难以预测的缺点,将导弹和目标视为一个结构随机跳变系统,并将目标作大机动当作系统的外部扰动输入,建立了该系统的数学模型,应用结构随机跳变系统理论对脱靶量的数学期望和方差进行了计算。通过仿真表明,该方法可对大机动目标进行制导误差预测,还可为变系数导引律的设计提供依据。