有线控制飞行器群脉冲耦合效应及加固方法研究

飞行器在飞行状态时，控制导线在电快速瞬变脉冲群（EFT）作用下，该设备控制指令将会出现控制状态错误翻转、持续无指令输出等故障，产生故障的机理是电磁脉冲（EMP）通过传导方式进入控制箱产生紊乱的回输信号所致，严重时会损坏控制器及起飞装置。在实验基础上，研究了飞行器控制导线对电磁脉冲的防护加固方法，研究结果表明，对控制导线采取屏蔽法能够使飞行器对电磁脉冲具有很好的防护效果。     

Spares stocking policies for repairable items with dependent repair times

This paper analyzes the problem of determining desirable spares inventory levels for repairable items with dependent repair times. The problem is important for repairable products such as aircraft engines which can have very large investment in spares inventory levels. While existing models can be used to determine optimal inventory spares levels when repair times are independent, the practical considerations of limited repair shop capacity and prioritized shop dispatching rules combine to make repair times not independent of one another. In this research a simulation model of a limited capacity repair facility with prioritized scheduling is used to explore a variety of heuristic approaches to the spares stocking decision. The heuristics are also compared with use of a model requiring independent repair times (even though that assumption is not valid here). The results show that even when repair time dependencies are present, the performance of a model which assumes independent repair times is quite good.     

Calculation of the cost of warranty policies as a function of estimated life distributions

Two types of warranties are analyzed. These are the free-replacement warranty, under which failed items are replaced free of charge until a specified total operating time has been achieved, and the pro rata warranty, under which items that fail prior to a specified time are replaced at pro rata cost to the buyer. Both the buyer's and seller's points of view are considered. The basis of the analysis is a comparison of warranted and unwarranted (otherwise identical) items with regard to long-run cost to the buyer and long-run profit to the seller. Application of the results requires knowledge of certain characteristics of the life distribution of the items in question. Parametric and nonparametric methods of estimation of these characteristics from incomplete data are discussed. Single and multiple failure-mode situations are considered. Some solutions to the problem are illustrated using incomplete data on failure times of an aircraft component.     

飞机发动机关键系统智能故障诊断方法

飞机发动机是一个非常复杂的大系统,由于其结构复杂,工作环境恶劣,对其关键系统的故障进行准确诊断始终是困扰业界的技术瓶颈之一。提出了采用EMD小波阈值降噪与主元分析相结合的方法,对飞机发动机气路系统故障诊断进行了深入研究。针对某型真实飞机发动机进行测试试验采集的气路多参量数据,首先采用经验模态分解(Empirical Mode Decomposition,EMD)对气路系统各参量信号进行EMD分解,然后采用软阈值函数对其进行降噪,并进行信号重构,从而可得到飞机发动机气路工作状态有效数据。在此基础上,设计了飞机发动机气路系统主元分析故障诊断模型,并结合预处理得到的飞机发动机气路有效数据,运用所设计的主元分析故障诊断模型对飞机发动机进行故障诊断技术研究。研究结果表明,所提出的方法能够很好地诊断出飞机发动机气路系统实际运行时所出现的故障,具有重要的实际应用价值,并有广泛的应用前景。     

飞机战伤修理浅析

论述了飞机战伤修理的必要性,战饬修理与平时修理的主要区别,战斗恢复力及其设计,战伤评估等战伤修理研究中的关犍问题。根据实际数据模拟出了飞机战斗力随作战持续天数及修理天数的变化曲线图。并对美军的野战条件下战伤评估流程图作了改进,提出了适合我军野战条件下的战伤评估逻辑图。     

装甲装备修理对象修理工作量的分布模型及应用

通过论述当今典型军队战时修理机构任务的划分,给出了装甲装备修理对象按照修理工作量和按照修理时间分布的2种模型,结合俄陆军各级修理机构修理时限的划分,计算得到了典型装甲装备的技术故障和战损产生的修理对象在各级修理机构的概率分布,为开展战损研究提供了一条新途径,对提高技术保障方案的准确性有积极作用。     

基于Multi-Agent的航空集群系统重构机理研究

集群作战是未来空中作战的主要样式,其重构机理的研究对于提升航空集群执行任务的整体性能以及在遭受攻击时的生存能力具有重要作用。从作战任务层面出发,对集群系统重构的定义以及类型、触发机制和基本原则进行了分析阐述;借鉴博弈论理论,将航空集群系统分布式重构问题映射为多Agent之间的合作-竞争问题,建立了基于Multi-Agent的系统重构模型,给出了重构的流程与算法,为航空集群系统自适应重构能力的设计实现提供了理论技术支持。     

Determination of the optimal investment in end products and repair resources

This paper demonstrates how to determine the minimal cost combination of end products and repair service capability in order to maintain a given level of operating end products. It is shown that the general rule for optimal resource allocation requires simply that the absolute value of the marginal factor cost of repair services divided by the marginal factor cost of end products be equal to the arrival rate of end products to repair. The model is applied to the problem of determining the resources required to support an operating level of Navy F-4 aircraft.     

Some approximations in multi-item,multi-echelon inventory systems for recoverable items

The optimization problem as formulated in the METRIC model takes the form of minimizing the expected number of total system backorders in a two-echelon inventory system subject to a budget constraint. The system contains recoverable items – items subject to repair when they fail. To solve this problem, one needs to find the optimal Lagrangian multiplier associated with the given budget constraint. For any large-scale inventory system, this task is computationally not trivial. Fox and Landi proposed one method that was a significant improvement over the original METRIC algorithm. In this report we first develop a method for estimating the value of the optimal Lagrangian multiplier used in the Fox-Landi algorithm, present alternative ways for determining stock levels, and compare these proposed approaches with the Fox-Landi algorithm, using two hypothetical inventory systems – one having 3 bases and 75 items, the other 5 bases and 125 items. The comparison shows that the computational time can be reduced by nearly 50 percent. Another factor that contributes to the higher requirement for computational time in obtaining the solution to two-echelon inventory systems is that it has to allocate stock optimally to the depot as well as to bases for a given total-system stock level. This essentially requires the evaluation of every possible combination of depot and base stock levels – a time-consuming process for many practical inventory problems with a sizable system stock level. This report also suggests a simple approximation method for estimating the optimal depot stock level. When this method was applied to the same two hypotetical inventory systems indicated above, it was found that the estimate of optimal depot stock is quite close to the optimal value in all cases. Furthermore, the increase in expected system backorders using the estimated depot stock levels rather than the optimal levels is generally small.     

Dynamic programming approach to the optimization of Naval aircraft rework and replacement policies

This paper describes a method for determining optimal repair and replacement policies for aireraft, with specific reference to the F–4. The objective of the analysis is to choose the set of policies from all possible alternatives over a finite planning horizon which minimizes the cost of operations. A dynamic program is presented which seeks an optimal path through a series of decision periods, when each period begins with the choice of keeping an aircraft, reworking it before further operation, or buying a new one. We do not consider changes in technology. Therefore, when a replacement does occur, it is made with a similar aircraft. Multivariate statistical techniques are used to estimate the relevant costs as a function of age, and time since last rework.     

飞机机翼结构损伤仿真研究

飞机结构的战伤模式及战伤程度预测对于制定战场抢修预案及改进战斗生存力设计具有重要意义。采用计算机模拟仿真技术定量分析了飞机机翼结构遭受射弹攻击后的损伤情况。通过损伤仿真讨论了3类情形,一是机翼结构受到简单的侵彻后的冲击效应;二是高速射弹攻击带有翼盒的机翼,而产生流体动力冲压效应;三是在射弹冲击模型中增加爆炸条件,研究射弹以任意角度冲击不同的位置产生的耦合效应。基于AN SY S/LS-DYNA仿真,给出了机翼结构损伤的结果,结论为战伤飞机战场抢修的快速评估提供了科学依据,也为飞机平时修理提供了参考。     

Involving the elephant: technical isolation and the role of India in a possible solution to the Iranian nuclear crisis

Apart from North Korea, no state's nuclear program in the twenty-first century has raised more concern to international security than Iran's. While Iran insists that its nuclear program is strictly for civilian purpose in line with Article IV of non-proliferation treaty, the USA and its allies insist that Iran has military intentions and called for sanctions. The failure of sanctions to deter Iran from its nuclear agenda had made many scholars and policy-makers call for a preemptive attack on Iranian nuclear facilities. Situated within this debate, this paper positions itself as an antagonist to the preemptive airstrike option and argues that involving India in a possible nuclear “iron curtain” against Iran – a move known as technical isolation – remains the best option to the current nuclear crises.     

基于战备完好率的军用飞机维修费用需求确定方法

军用飞机维修费用需求与战备完好率要求密切相关,为保持飞机一定的战备完好率水平,必须投入一定的维修费用。维修费用投入多,则维修设备齐全,维修人员维修能力高,维修备件充足,飞机故障修复时间短,战备完好率高;维修费用投入少,会造成维修设备短缺,设施破旧,维修人员培训不到位,维修备件供应不足等各种问题,直接影响战备完好率水平。     

航母编队在对空防御中预警机空域配置的方法

航母编队在对空防御中,通常利用预警机机载雷达探测距离远的优势实施对空预警,以提高编队防空作战能力。基于预警机的任务,提出了预警机空域配置的基本要求,分析了预警机前出距离、预警距离、预警扇面角与巡逻线长度之间制约关系,并建立了模型。在此基础上进行仿真分析。仿真结果证明该方法实用、可行,为对空防御中预警机空域的配置提供了参考依据。     

Fighter aircraft acquisition in Croatia: failure of policy delivery

The possibility for Croatia to obtain new fighter aircraft is not new, as this option has been publicly debated for at least a decade. A sudden decision to advance the acquisition of a limited number of fighter aircraft was made in 2017 with an international tendering process concluding in early 2018. Through open source material, this paper will look at this procurement process by examining the relationship between policy and strategic thinking on the one side, and policy delivery on the other, and evaluate why the tendering process failed in achieving envisaged results. The paper concludes that the problems facing the Croatian aircraft acquisition process stem from at least two interrelated factors: firstly, at the operational level, the failure of the procurement was the direct result of mismanaged tendering procedures linked to the wider public administration reform process; and secondly, at the strategic level, inherently complex civil-military relations and related cultural aspects which have not been adequately addressed over the past decades. The result was a failure to deliver on government policy, something which this paper argues will need to be addressed over the medium to long term.     

Customer delays in M/M/c repair systems with spares

A service center to which customers bring failed items for repair is considered. The items are exchangeable in the sense that a customer is ready to take in return for the failed item he brought to the center any good item of the same kind. This exchangeability feature makes it possible for the service center to possess spares. The focus of the article is on customer delay in the system—the time that elapses since the arrival of a customer with a failed item and his departure with a good one—when repaired items are given to waiting customers on a FIFO basis. An algorithm is developed for the computation of the delay distribution when the item repair system operates as an M/M/c queue.     

The Shi Lang,a vehicle for regional change?

In a succession of disclosures over the summer of 2011, the People's Republic of China acknowledged the near completion of its first aircraft carrier and the initiation of a carrier building program. These revelations have come at a time of increased tension in the South China Sea on top of the wider worries in the region concerning China's overly assertive stance and the pace of its military modernization. This perspective will examine why the status of the vessel and the program have now been made public, in addition to surveying the wider implications this upgrade to Chinese maritime capabilities will have on the stability of the region over the coming years. However, this paper concludes that there is, at present, no reason for the sensationalism nor the threat‐mongering seen in many media outlets, of late. Hastily drawn conclusions based primarily on realpolitik fail to understand the nuances of this issue.     

编队超视距空战效能评估方法

现有的两步裁定空战模型大多直接借鉴基于飞机易损性的先敌发射概率计算方法,而各种飞机的易损性无法通过解析模型来获取,因此降低了模型的通用性.在现有的研究基础上提出了作战飞机先敌发射指数概念,并基于空战双方的先敌发射指数提出了新的先敌发射概率计算模型和更为具体的编队超视距空战效能评估模型.最后给出了相关实例进行验证.     

MAD: Mathematical analysis of downtime

The MAD model presents a mathematic treatment of the relationship between aircraft reliability and maintainability, system manning and inspection policies, scheduling and sortie length, and aircraft downtime. Log normal distributions are postulated for subsystem repair times and simultaneous repair of malfunctions is assumed. The aircraft downtime for maintenance is computed with the distribution of the largest of k log normal distributions. Waiting time for maintenance men is calculated either by using a multiple-channel queuing model or by generating the distribution of the number of maintenance men required and comparing this to the number of men available to determine the probability of waiting at each inspection.     

Heuristics for multicomponent joint replacement: Applications to aircraft engine maintenance

This paper considers the maintenance of aircraft engine components where economies exist for joint replacement because (a) the aircraft must be pulled from service for maintenance and (b) repair of some components requires removal and disassembly of the engine. It is well known that the joint replacement problem is difficult to solve exactly, because the optimal solution does not have a simple structured form. Therefore, we formulate three easy-to-implement heuristics and test their performance against a lower bound for various numerical examples. One of our heuristics, the base interval approach, in which replacement cycles for all components are restricted to be multiples of a specified interval, is shown to be robustly accurate. Moreover, this heuristic is consistent with maintenance policies used by commercial airlines in which periodic maintenance checks are made at regular intervals. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 435–458, 1998