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271.
武警部队担负着抢险救灾的任务,有必要对其应急救援能力进行科学评估。在分析对比当前应急救援能力评价方法存在不足基础上,构建了新的评价模式,为武警部队提高应急救援能力提供了一种新的借鉴依据。通过实证证明了该评价体系的科学性和评价方法的可操作性。 相似文献
272.
In this study, we explore an inventory model for a wholesaler who sells a fashion product through two channels with asymmetric sales horizons. The wholesaler can improve profitability by employing joint procurement and inventory reallocation as a recourse action in response to the dynamics of sales. In this research, a simple stochastic programming model is analyzed to specify the properties of the optimal inventory decisions. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011 相似文献
273.
针对反潜巡逻机使用磁探仪和自导深弹的攻潜效能研究,提出了一种基于蒙特卡洛法的计算模型。在建立攻潜坐标系的基础上,给出了连投深弹射击深度的定义;结合磁探仪定位原理,提出了基于峰值追踪的定位目标和连投攻击的方法,仿真结果表明该方法能够提高命中概率;给出了目标分布和连投深弹的散布模型,依据攻潜过程和命中判定条件,进行了攻潜效能的计算;仿真分析了影响攻潜效能的主要因素,并研究了投弹间隔的确定方法。 相似文献
274.
根据航天试验综合能力评估的特点和要求,依据系统工程的理论方法,确定了装备、人员和保障能力为主要评估要素,设置了评估层次和控制点,建立了航天试验综合能力评估模型。该模型由下至上分为3个层次:基础层主要对分系统各岗位人员和所属装备进行评估;分系统层主要对人员素质、装备性能和保障能力进行评估;系统层主要对整个系统的综合试验能力进行评估。通过实例表明该模型大大提高了航天试验综合能力量化评估的准确性。 相似文献
275.
Jia-xing Song Tao Guo Miao Yao Jia-lin Chen Wen Ding Feng-li Bei Xiao-nan Zhang Qin Yin Jun-yi Huang Chang-hao Li 《防务技术》2021,17(4):1289-1295
Fluoropolymers get increasing attention in energetic materials application due to the high fluorine content. To explore the effect of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) on Al/MnO2 nanothermite, the samples with different contents are prepared and characterized by SEM, TG-DSC, XRD, and their ignition and combustion behavior are tested and recorded. The results show that P(VDF-HFP) as an energetic binder can combine the nanothermite components together, even exist in the gaps. The integrity of energetic materials has been improved. Thermal analysis shows that the addition of P(VDF-HFP) greatly changes the thermal reaction processes, and the exothermic peaks appear early, but the utilization of fuel and oxidizer is not efficient from the XRD results. Furthermore, the appropriate addition of P(VDF-HFP) can directly reduce the ignition energy threshold and increase the combustion time, which is necessary for the potential ignition charge application. The possible reasons for above phenomena are discussed and analyzed. This research provides a reference for improvement of thermite-based ignition charge formulation. 相似文献
276.
Su-wei Wang Xiu-duo Song Zong-kai Wu Lei Xiao Guang-pu Zhang Yu-bing Hu Ga-zi Hao Wei Jiang Feng-qi Zhao 《防务技术》2021,17(6):1954-1966
The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base (CMDB) propellant. Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process. To improve the accuracy of the simulation results, material parameters and model structure were corrected based on actual conditions, and adaptive grid technology was applied in the local mesh refinement. In addition, the rheological behavior, motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps, rotational rates and temperatures of two rollers. The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet. Compared with the gap, the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging. Meanwhile, under the synergistic effect of contact heat transfer as well as convective heat exchange, heat accumulated near the outlet and diffused along the reflux movement, which led to the countercurrent heat dissipation behavior of CMDB propellant slurry. The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored, which provided theoretical guidance and reference data for the optimization of calendering process conditions. Based on the simulation results, the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle. 相似文献
277.
Chang-gui Song Xiao-dong Li Yue Yang Hui-min Liu Ying-xin Tan Jing-yu Wang 《防务技术》2021,17(6):1936-1943
The core-shell 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-Trinitrotoluene (CL-20/TNT) composite was prepared by spray-drying method in which sensitive high energy explosive (CL-20) was coated with insensitive explosive (TNT). The structure and properties of different formulations of CL-20/TNT composite and CL-20/TNT mixture were characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Laser particle size analyzer, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), impact sensitivity test and detonation performance. The results of SEM, TEM, XPS and XRD show that ϵ-CL-20 particles are coated by TNT. When the ratio of CL-20/TNT is 75/25, core-shell structure is well formed, and thickness of the shell is about 20–30 nm. And the analysis of heat and impact show that with the increase of TNT content, the TNT coating on the core-shell composite material can not only catalyze the thermal decomposition of core material (CL-20), but also greatly reduce the impact sensitivity. Compared with the CL-20/TNT mixture (75/25) at the same ratio, the characteristic drop height of core-shell CL-20/TNT composite (75/25) increased by 47.6% and the TNT coating can accelerate the nuclear decomposition in the CL-20/TNT composites. Therefore, the preparation of the core-shell composites can be regarded as a unique means, by which the composites are characterized by controllable decomposition rate, high energy and excellent mechanical sensitivity and could be applied to propellants and other fields. 相似文献
278.
279.
研究了小波系数的分布规律和统计特性,分析了各种小波系数对恢复图象质量的影响,从而为基于小波变换的图象数据压缩提供了量化方法。 相似文献
280.