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961.
962.
963.
研究了装备器材管理的成本构成特点,认为装备器材多极库存系统可简化为n级系列体系结构。建立了装备器材多级库存优化控制模型,通过模型求解和相应实例分析,表明了装备器材多级库存优化控制方法的可行性和有效性。 相似文献
964.
非晶碳类金刚石薄膜摩擦学特性及其应用 总被引:1,自引:0,他引:1
综合地介绍了类金刚石膜研究现状,着重说明了非晶碳类金刚石薄膜的摩擦学特性,分析了沉积方法、掺杂元素、摩擦环境、基体及对偶材料对其摩擦学特性的影响。最后,简要说明了非晶碳类金刚石膜应用情况。 相似文献
965.
基于快照日志分析的数据同步方法 总被引:5,自引:0,他引:5
在大型信息系统的开发中,分布式数据库和分布式应用系统间的数据同步问题是一个较难解决的问题,现有的各种解决方案存在着难以反映源数据频繁变化、工作效率低以及应用程序间协调困难和部署管理复杂等问题。通过对Oracle数据库的数据复制机制的研究,提出了基于快照日志分析的数据同步方法,介绍了快照日志的数据结构、对数据库操作的记录方式,并阐述了提取快照日志记录的增量变化的日志分析算法,对于实现事务操作频繁的数据表间的数据同步提供了一种新思路。 相似文献
966.
Hai-bin Xu Long-kui Chen De-zhi Zhang Fang-ping Zhang Zhao-wu Shen Wen-xiang Liu Sheng-hong Huang 《防务技术》2021,17(3):1071-1080
The mitigation of blast shock with water has broad application prospects. Understanding the mitigation effects on the reflected overpressure of the explosion shock with water surrounding an explosive in a confined space is of great significance for military explosives safety applications. To estimate the effects of the parameters on the reflected overpressure of blasted shock wave, a series of experiments were carried out in confined containers with spherical explosives immersed in a certain thickness of water, and numerical simulations were conducted to explore the corresponding mechanisms. The results reveal that the reflected overpressure is abnormally aggravated at a small scaled distance. This aggravation is due to the high impulse of the bulk accelerated water shell converted from the explosion. With increasing scaled distance, the energy will be gradually dissipated. The mitigation effects will appear with the dispersed water phase front impacting at a larger scaled distance, except in the case of a dense water phase state. A critical scaled distance range of 0.7—0.8 m/kg1/3 for effective mitigation was found. It is suggested that the scaled distance of space walls should be larger than the critical value for a certain water-to-explosive weight ratio range (5—20). 相似文献
967.
美军认为,近年来中俄等大国的军事实力不断增强,成为美国的主要安全威胁,长期的反叛乱作战也使美国陆军应对正规战争的能力有所下降,必须推进面向大国竞争的转型建设以适应未来的作战环境。随着美国陆军转型建设的大幕拉开,提升大规模作战能力成为其建设发展的焦点。本文认为,旅战斗队作为美国陆军的主要合成兵种部队与实施近距离地面作战的主要梯队之一,其建设发展必将服务于美国陆军的战略目标。据此,美国陆军旅战斗队围绕“跨域、集中、持续、聚合”四个指导原则,重点采取各种举措提升其指挥机构生存力、火力集中打击力、空中威胁防护力、战术网络杀伤力四项基本能力。总结分析美国陆军旅战斗队发展建设的举措,对军队未来作战能力建设具有一定的启示作用。 相似文献
968.
This study investigates and quantifies some possible sources affecting the position of impact points of small caliber spin-stabilized projectiles (such as 12.7 mm bullets). A comparative experiment utilizing the control variable method was designed to figure out the influence of tiny eccentric centroids on the projectiles. The study critically analyzes data obtained from characteristic parameter measurements and precision trials. It also combines Sobol's algorithm with an artificial intelligence algorithm—Adaptive Neuro-Fuzzy Inference Systems (ANFIS)—in order to conduct global sensitivity analysis and determine which parameters were most influential. The results indicate that the impact points of projectiles with an entry angle of 0° deflected to the left to that of projectiles with an entry angle of 90°. The difference of the mean coordinates of impact points was about 12.61 cm at a target range of 200 m. Variance analysis indicated that the entry angle — i.e. the initial position of mass eccentricity — had a notable influence. After global sensitivity analysis, the significance of the effect of mass eccentricity was confirmed again and the most influential factors were determined to be the axial moment and transverse moment of inertia (Izz Iyy), the mass of a projectile (m), the distance between nose and center of mass along the symmetry axis for a projectile (Lm), and the eccentric distance of the centroid (Lr). The results imply that the control scheme by means of modifying mass center (moving mass or mass eccentricity) is promising for designing small-caliber spin-stabilized projectiles. 相似文献
969.
In this paper, based on a bidirectional parallel multi-branch feature pyramid network (BPMFPN), a novel one-stage object detector called BPMFPN Det is proposed for real-time detection of ground multi-scale targets by swarm unmanned aerial vehicles (UAVs). First, the bidirectional parallel multi-branch convolution modules are used to construct the feature pyramid to enhance the feature expression abilities of different scale feature layers. Next, the feature pyramid is integrated into the single-stage object detection framework to ensure real-time performance. In order to validate the effectiveness of the proposed algorithm, experiments are conducted on four datasets. For the PASCAL VOC dataset, the proposed algorithm achieves the mean average precision (mAP) of 85.4 on the VOC 2007 test set. With regard to the detection in optical remote sensing (DIOR) dataset, the proposed algorithm achieves 73.9 mAP. For vehicle detection in aerial imagery (VEDAI) dataset, the detection accuracy of small land vehicle (slv) targets reaches 97.4 mAP. For unmanned aerial vehicle detection and tracking (UAVDT) dataset, the proposed BPMFPN Det achieves the mAP of 48.75. Compared with the previous state-of-the-art methods, the results obtained by the proposed algorithm are more competitive. The experimental results demonstrate that the proposed algorithm can effectively solve the problem of real-time detection of ground multi-scale targets in aerial images of swarm UAVs. 相似文献
970.
Liquid-filled compartment structure consists of a bulk steel plate with matrix blind holes which are filled with liquid and a steel front plate to seal up the liquid with rings and bolts.The liquid-filled compart-ment structure can resist the shaped charge warhead effectively.This paper presents experimental and theoretical investigations of the penetration ability of the residual shaped charge jet emerging from the liquid-filled compartment structure after the penetration process at different impact angles.On the basis of shock wave propagation theory,the influence of the liquid-filled compartment structure on jet sta-bility is analysed.The interferences of the liquid backflow caused by a reflected shock wave and a back plate on jet stability under different impact angles are also examined.In addition,the range of the disturbed velocity segments of the jet at different impact angles and the penetration ability of the re-sidual jet are obtained.A theoretical model is validated against the experimental penetration depths. 相似文献