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691.
Ronald D. Fricker 《海军后勤学研究》1998,45(1):1-22
This paper revisits the modeling by Bracken [3] of the Ardennes campaign of World War II using the Lanchester equations. It revises and extends that analysis in a number of ways: (1) It more accurately fits the model parameters using linear regression; (2) it considers the data from the entire campaign; and (3) it adds in air sortie data. In contrast to previous results, it concludes by showing that neither the Lanchester linear or Lanchester square laws fit the data. A new form of the Lanchester equations emerges with a physical interpretation. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 1–22, 1998 相似文献
692.
石油及其产品在储存过程中,受到工艺技术、设备以及管理方法的限制,不可避免会有部分轻质组分汽化,逸入大气,对环境造成污染,并造成经济损失。这种因自然损耗对储油经济带来的影响因素很多,既有定性的,又有定量的,且各因素大多又难以精确地描述,因此,为了反映这些不确定因素对油罐储油经济性的影响,运用多级模糊综合评判的方法,对储油经济性进行综合评判。该方法的思路是建立一个经济效能三级模糊综合评判指标体系,构建相应的评判模型,并以算例加以验证。分析计算结果表明:该方法能较好考虑到评判中的模糊因素,为客观准确评估储油经济效能提供了科学依据。 相似文献
693.
平台式惯导系统初始对准最佳可观性分析 总被引:1,自引:0,他引:1
首先应用线性系统的奇异值分解理论对静基座初始对准的可观性及可观度进行了深入地分析.给出了不同奇异值下系统状态可观性状况的直方图,并且计算出不同状态组合时系统奇异值的大小及对可观性的影响.理论分析表明选取(△)N、(△)E、εE为不可观测时,系统的估计效果最好.其次采用卡尔曼滤波器对可观阵的秩为7的三种状态组合进行最优估计,仿真结果验证这种论断的正确性.最后从误差分析的角度阐述了这种论断的合理性. 相似文献
694.
695.
经典的侦察与监测(S&R)系统效能分析方法存在模型难以建立、结果不准确等问题。考虑到S&R系统的目的是提供情报支持,提出一种基于信息需求的S&R系统情报支持效能分析方法。该方法以用户的信息需求为度量基准量,比较S&R系统性能对信息需求的满足度,并以此满足度作为S&R系统效能度量的指标。仿真实例表明了新方法的有用性。 相似文献
696.
697.
为减小单星测频定位的误差,提出一种融合初值校准与二阶逼近的单星测频定位算法。该算法在卫星接收信号多普勒频移为零的时间点,通过测距获得卫星到定位目标的距离信息,利用距离信息修正轨道平面与定位目标的几何关系,为初值的选取提供校准手段;将校准的初值代入含二阶级数的定位方程泰勒展开式,通过较少次数的迭代得到定位目标的真实位置,从而降低定位的算法复杂度,提高定位精度。仿真结果表明,所提出的算法与多普勒单星定位算法相比,迭代次数和定位误差大幅度减小,其实现简单、计算量少、误差小,在单星定位研究领域具有较高的理论价值和实用价值。 相似文献
698.
《防务技术》2020,16(2):362-373
An increase in the use of the gun barrel will cause wear of the inner wall, which reduces the muzzle velocity and the spin rate of the projectile. The off-bore flight attitude and trajectory of the projectile also change, affecting the shooting power and the accuracy. Exterior ballistic data of a high-speed spinning projectile are required to study the performance change. Therefore, based on the barrel's accelerated life test, the whole process of projectile shooting is reproduced using numerical simulation technology, and key information on the ballistic performance change at each shooting stage are acquired. Studies have shown that in the later stages of barrel shooting, the accuracy of shooting has not decreased significantly. However, it is found that the angle of attack of the projectile increases as the wear of the barrel increases. The maximum angle of attack reaches 0.106 rad when the number of shots reaches 4300. Meanwhile, elliptical bullet hole has appeared on the target at this shooting stage. Through combining external ballistic theory with simulation results, the primary reason of this phenomenon is found to be a significant decrease in the muzzle spin rate of the projectile. At the end of the barrel life, the projectile muzzle spin rate is 57.5% lower than that of a barrel without wear. 相似文献
699.
《防务技术》2020,16(1):96-106
The numerical simulation of a blast wave of a multilayer composite charge is investigated. A calculation model of the near-field explosion and far-field propagation of the shock wave of a composite charge is established using the AUTODYN finite element program. Results of the near-field and far-field calculations of the shock wave respectively converge at cell sizes of 0.25–0.5 cm and 1–3 cm. The Euler––flux-corrected transport solver is found to be suitable for the far-field calculation after mapping. A numerical simulation is conducted to study the formation, propagation, and interaction of the shock wave of the composite charge for different initiation modes. It is found that the initiation mode obviously affects the shock-wave waveform and pressure distribution of the composite charge. Additionally, it is found that the area of the overpressure distribution is greatest for internal and external simultaneous initiation, and the peak pressure of the shock wave exponentially decays, fitting the calculation formula of the peak overpressure attenuation under different initiation modes, which is obtained and verified by experiment. The difference between numerical and experimental results is less than 10%, and the peak overpressure of both internal and external initiation is 56.12% higher than that of central single-point initiation. 相似文献
700.
《防务技术》2020,16(5):969-979
Shock wave is emitted into the plate and sphere when a sphere hypervelocity impacts onto a thin plate. The fragmentation and phase change of the material caused by the propagation and unloading of shock wave could result in the formation of debris cloud eventually. Propagation models are deduced based on one-dimensional shock wave theory and the geometry of sphere, which uses elliptic equations (corresponding to ellipsoid equations in physical space) to describe the propagation of shock wave and the rarefaction wave. The “Effective thickness” is defined as the critical plate thickness that ensures the rarefaction wave overtake the shock wave at the back of the sphere. The “Effective thickness” is directly related to the form of the debris cloud. The relation of the “Effective thickness” and the “Optimum thickness” is also discussed. The impacts of Al spheres onto Al plates are simulated within SPH to verify the propagation models and associated theories. The results show that the wave fronts predicted by the propagation models are closer to the simulation result at higher impact velocity. The curvatures of the wave fronts decrease with the increase of impact velocities. The predicted “Effective thickness” is consistent with the simulation results. The analysis about the shock wave propagation and unloading in this paper can provide a new sight and inspiration for the quantitative study of hypervelocity impact and space debris protection. 相似文献