大口径机枪结构动力学建模方法研究

总结了我国近年来关于大口径机枪结构动力学建模方法研究的主要成果,分析了目前建模方法上存在的某些问题以及对武器装备研制的影响,进一步介绍了边界条件的确定、模型正确性判别和载荷识别等方面的新技术。     

Algorithms for solving the conditional covering problem on paths

Consider the conditional covering problem on an undirected graph, where each node represents a site that must be covered by a facility, and facilities may only be established at these nodes. Each facility can cover all sites that lie within some common covering radius, except the site at which it is located. Although this problem is difficult to solve on general graphs, there exist special structures on which the problem is easily solvable. In this paper, we consider the special case in which the graph is a simple path. For the case in which facility location costs do not vary based on the site, we derive characteristics of the problem that lead to a linear‐time shortest path algorithm for solving the problem. When the facility location costs vary according to the site, we provide a more complex, but still polynomial‐time, dynamic programming algorithm to find the optimal solution. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

Outsourcing warranty repairs: Dynamic allocation

In this paper we consider the problem of minimizing the costs of outsourcing warranty repairs when failed items are dynamically routed to one of several service vendors. In our model, the manufacturer incurs a repair cost each time an item needs repair and also incurs a goodwill cost while an item is awaiting and undergoing repair. For a large manufacturer with annual warranty costs in the tens of millions of dollars, even a small relative cost reduction from the use of dynamic (rather than static) allocation may be practically significant. However, due to the size of the state space, the resulting dynamic programming problem is not exactly solvable in practice. Furthermore, standard routing heuristics, such as join‐the‐shortest‐queue, are simply not good enough to identify potential cost savings of any significance. We use two different approaches to develop effective, simply structured index policies for the dynamic allocation problem. The first uses dynamic programming policy improvement while the second deploys Whittle's proposal for restless bandits. The closed form indices concerned are new and the policies sufficiently close to optimal to provide cost savings over static allocation. All results of this paper are demonstrated using a simulation study. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

On parallel machine replacement problems with general replacement cost functions and stochastic deterioration

The parallel machine replacement problem consists of finding a minimum cost replacement policy for a finite population of economically interdependent machines. In this paper, we formulate a stochastic version of the problem and analyze the structure of optimal policies under general classes of replacement cost functions. We prove that for problems with arbitrary cost functions, there can be optimal policies where a machine is replaced only if all machines in worse states are replaced (Worse Cluster Replacement Rule). We then show that, for problems with replacement cost functions exhibiting nonincreasing marginal costs, there are optimal policies such that, in any stage, machines in the same state are either all kept or all replaced (No‐Splitting Rule). We also present an example that shows that economies of scale in replacement costs do not guarantee optimal policies that satisfy the No‐Splitting Rule. These results lead to the fundamental insight that replacement decisions are driven by marginal costs, and not by economies of scale as suggested in the literature. Finally, we describe how the optimal policy structure, i.e., the No‐Splitting and Worse Cluster Replacement Rules, can be used to reduce the computational effort required to obtain optimal replacement policies. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

防空兵群动态防空抗击效率评估模型研究

结合未来陆军机动作战实际,研究了集中射击指挥条件下,防空兵群动态防空抗击效率的评估方法。提出了目标可射击概率应依据火力单位射程选用不同模型评估的观点,探讨了火力单位转移、导弹(弹药)储备和群指挥所状态等因素对群抗击效率的影响及其评估模型。在此基础上,指出了所建模型的适用范围和需要进一步解决的问题。     

温度场对机枪动力特性的影响

现代机枪重量较轻,要达到理想的射击精度就必须保证良好的动力匹配关系。机枪在射击过程中,枪管温度的升高直接影响机枪的动力特性。对某型机枪射击过程中枪管温度场及其对机枪动力特性的影响进行了分析,结果表明,温度变化对机枪动力特性改变的影响较小。     

水下滑翔机建模与纵向运动控制

水下滑翔机是一种浮力驱动的新型水下航行器,其特殊的驱动方式和结构特点增加了建模和控制分析的复杂度。为获得准确有效的水下运动控制方法,通过滑翔机运动学和动力学分析,建立了较为完善的三维空间数学模型,并进行了合理的假设和简化,得到纵平面内小扰动线性化模型。在此基础上,运用了线性二次型最优控制理论设计了LQR调节器,分析系统对于控制指令的跟踪响应情况。最后针对滑翔机的纵平面运动进行了仿真分析,仿真结果显示,LQR调节器有很好的干扰抑制能力和指令跟踪性能,并准确地描述了纵平面内滑翔机的运动特性。     

模糊优选动态规划在稀缺军事资源配置中的应用

在对稀缺军事资源配置问题进行数学描述的基础上,建立起评价指标相对优属度计算模型,实现了局部优选。在此基础上,通过分配目标综合评价模型实现了对局部优选数据的综合处理,最后建立资源分配的动态规划模型实现了对方案的优选。最后通过实例演示了解决该类问题的具体方法和步骤,对部队建设具有一定的参考和应用价值。     

模糊离散动态贝叶斯网络的目标威胁等级评估

动态贝叶斯网络作为一种智能推理工具在处理不确定推理问题中显示出强大的生命力,但是存在难于处理连续变量的推理问题。将模糊理论与动态贝叶斯网络相结合,提出一种模糊分类的方法,将连续变量模糊分类为动态贝叶斯网络能够应用的证据信息用于推理,并建立目标威胁等级评估模型,应用直接推理算法对该网络进行推理。仿真结果表明,该分类方法与动态贝叶斯网络结合能够很好地处理连续变量推理的问题。     

Modeling the operation of multireservoir systems using decomposition and stochastic dynamic programming

Stochastic dynamic programming models are attractive for multireservoir control problems because they allow non‐linear features to be incorporated and changes in hydrological conditions to be modeled as Markov processes. However, with the exception of the simplest cases, these models are computationally intractable because of the high dimension of the state and action spaces involved. This paper proposes a new method of determining an operating policy for a multireservoir control problem that uses stochastic dynamic programming, but is practical for systems with many reservoirs. Decomposition is first used to reduce the problem to a number of independent subproblems. Each subproblem is formulated as a low‐dimensional stochastic dynamic program and solved to determine the operating policy for one of the reservoirs in the system. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006