Modeling and analyzing multiple station baggage screening security system performance

In the aftermath of the tragic events of 11 September 2001, numerous changes have been made to aviation security policy and operations throughout the nation's airports. The allocation and utilization of checked baggage screening devices is a critical component in aviation security systems. This paper formulates problems that model multiple sets of flights originating from multiple stations (e.g., airports, terminals), where the objective is to optimize a baggage screening performance measure subject to a finite amount of resources. These measures include uncovered flight segments (UFS) and uncovered passenger segments (UPS). Three types of multiple station security problems are identified and their computational complexity is established. The problems are illustrated on two examples that use data extracted from the Official Airline Guide. The examples indicate that the problems can provide widely varying solutions based on the type of performance measure used and the restrictions imposed by the security device allocations. Moreover, the examples suggest that the allocations based on the UFS measure also provide reasonable solutions with respect to the UPS measure; however, the reverse may not be the case. This suggests that the UFS measure may provide more robust screening device allocations. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

Priority and dynamic scheduling in a make‐to‐stock queue with hyperexponential demand

We consider the scheduling problem in a make‐to‐stock queue with two demand classes that can be differentiated based on their variability. One class experiences Poisson arrivals and the other class experiences hyperexponential renewal arrivals. We provide an exact analysis of the case where the demand class with higher variability is given non‐preemptive priority. The results are then used to compare the inventory cost performance of three scheduling disciplines, first‐come first‐serve and priority to either class. We then build on an existing dynamic scheduling heuristic to propose a modification that works well for our system. Extensions of the heuristic to more than two classes and to the case where demand state is known are also discussed. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.     

基于改进支持向量机的航空装备维修安全评估

传统航空装备维修安全评估大多采用定性评估方法,针对传统评估中存在主观性、随意性过强,实践中缺乏可操作性等问题,提出了基于核密度估计的改进支持向量机。构建了航空装备维修安全评估指标体系,在利用层次分析法对其权重进行计算的基础上,通过改进支持向量机对某单位航空装备维修状况进行了全面评估,为航空装备维修安全评估提供了科学的方法,对确保航空装备维修安全具有较强的理论和现实意义。     

Security gradient and national defense – the optimal choice between a draft army and a professional army

The earlier work on the optimal design of the national security has focused on the opportunity cost of the draft in terms of foregone human capital formation. The current paper introduces the national security into the welfare analysis missing from the earlier work. This creates a trade-off between the private goods and the security as a public good in the social cost–benefit analysis. There are three major results. First, and arising from the intergenerational interaction, it is optimal to introduce a pay to the young generation when in duty even by resorting to a distortive tax. Second, when optimizing the size of the army, the optimal choice between the draft army and the professional army depends on the risk class of the country. A security gradient arises. Third, the choice is linked to the size and the quality of the reserve generated by the two approaches.     

以可靠性为中心的维修

以可靠性为中心的维修(Reliability Centered maintenance——RCM)是美国航空界和美国防部制订装备预防维修大纲时所使用的一种维修理论,其主要目的是以最低的费用保持复杂装备的固有可靠性水平。本文跟踪RCM的发展过程,简述其基本原理和基本内容,并在综述国内外有关文献的基础上提出了笔者对RCM的认识及在军械系统应用RCM的必要性。     

Multi-period airline overbooking with multiple fare classes

Consider a multi-period multi-fare class airline overbooking problem that relates to a single-leg flight. Passengers may cancel their reservations at any time, including being no-shows at flight-time. Canceling passengers receive a refund that depends on their fare class, e.g., supersaver, coach, etc. At flight-time, the airline bumps passengers in excess of flight capacity and pays a penalty for so doing. A continuous state-space dynamic programming model is developed in which the state is the numbers of reservations currently on hand in each fare class. In each period, reservation requests occur in only one fare class and the fraction of reservations canceling in each class is independent of the number of reservations therein. A booking-limit policy is optimal, i.e., in each period the airline accepts reservation requests up to a booking limit if the number of initial reservations in the fare class is less than the booking limit, and declines reservation requests otherwise. The booking limits for each class depend on the numbers of reservations in the other classes. When there are two fare classes the optimal booking limits in each class decrease with the number of reservations in the other class. © 1996 John Wiley & Sons, Inc.     

A partial characterization of the optimal ordering/rationing policy for a periodic review system with two demand classes and backordering

We consider a finite horizon periodic review, single product inventory system with a fixed setup cost and two stochastic demand classes that differ in their backordering costs. In each period, one must decide whether and how much to order, and how much demand of the lower class should be satisfied. We show that the optimal ordering policy can be characterized as a state dependent (s,S) policy, and the rationing structure is partially obtained based on the subconvexity of the cost function. We then propose a simple heuristic rationing policy, which is easy to implement and close to optimal for intensive numerical examples. We further study the case when the first demand class is deterministic and must be satisfied immediately. We show the optimality of the state dependent (s,S) ordering policy, and obtain additional rationing structural properties. Based on these properties, the optimal ordering and rationing policy for any state can be generated by finding the optimal policy of only a finite set of states, and for each state in this set, the optimal policy is obtained simply by choosing a policy from at most two alternatives. An efficient algorithm is then proposed. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于作业成本原理的飞行训练保障费用模型

飞行训练保障费用是飞机使用保障费用中的重要组成部分,也是使用保障费用估算的重点和难点。结合目前航空兵部队实际工作情况,首先利用作业成本法的基本原理,对航空兵部队飞行保障阶段的作业进行划分,得出成本库及成本动因。其次针对军机飞行保障阶段的多种作业,建立基于作业成本法的飞行训练保障费用模型。最后通过算例说明其比其他估算方法所具备的优势。     

航空随队支援干扰掩护区仿真建模研究

干扰暴露区及干扰扇面等传统评估指标对静态干扰部署可以进行有效评估分析,对机动干扰掩护难以进行准确描述分析。为有效评估电子对抗航空兵随队支援干扰能力,以及准确进行航空兵突防编队配置及干扰力量需求分析,引入了干扰掩护区的概念,并建立相关模型进行仿真计算,得出3条电子对抗随队支援航空兵突防的运用启示。     

Optimal maintenance policies for serial,multi‐machine systems with non‐instantaneous repairs

We study optimal age‐replacement policies for machines in series with non‐instantaneous repair times by formulating two nonlinear programs: one that minimizes total cost‐rate subject to a steady‐state throughput requirement and another that maximizes steady‐state throughput subject to a cost‐rate budget constraint. Under reasonable assumptions, the single‐machine cost‐optimal and throughput‐optimal solutions are unique and orderable, and the multi‐machine optimal solutions have appealing structure. Furthermore, we establish equivalence between the two formulations and provide an illustrative numerical example. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

直升机野战油料保障模拟优化研究

野战条件下,场站通常在前沿阵地开设野战直升机场实施伴随保障,其中油料保障主要采取飞机加油车先对直升机实施加油,后到野战机场油库领取油料这一方式进行。若将野战直升机场油料保障作为一个系统来研究,要实现适时、适量的油料保障,确定合适的飞机加油车及野战机场油库发油鹤位数量是一个关键问题。利用GPSSW语言对这一问题进行模拟,得出模拟结果并进行统计分析,经反复模拟和参数比较得到适合的参数,为部队保障提供依据。     

边检机关在处置口岸突发事件中的作用

口岸突发事件,是指在出入境口岸限定区域突然发生的危害社会治安、损害人民生命财产安全和国家利益的事件。及时、有效地预防和处置口岸突发事件,对于维护国家的主权和领土完整,保证人民的生命财产不受侵害,保护出入境人员和交通工具的安全,维持口岸的正常出入境秩序,促进口岸的发展具有重要意义。出入境边防检查机关是否能够迅速、稳妥地处置口岸突发事件,将口岸突发事件的不良结果降到最低,有着责无旁贷和不可替代的作用。     

A three‐stage procurement optimization problem under uncertainty

This article examines a problem faced by a firm procuring a material input or good from a set of suppliers. The cost to procure the material from any given supplier is concave in the amount ordered from the supplier, up to a supplier‐specific capacity limit. This NP‐hard problem is further complicated by the observation that capacities are often uncertain in practice, due for instance to production shortages at the suppliers, or competition from other firms. We accommodate this uncertainty in a worst‐case (robust) fashion by modeling an adversarial entity (which we call the “follower”) with a limited procurement budget. The follower reduces supplier capacity to maximize the minimum cost required for our firm to procure its required goods. To guard against uncertainty, the firm can “protect” any supplier at a cost (e.g., by signing a contract with the supplier that guarantees supply availability, or investing in machine upgrades that guarantee the supplier's ability to produce goods at a desired level), ensuring that the anticipated capacity of that supplier will indeed be available. The problem we consider is thus a three‐stage game in which the firm first chooses which suppliers' capacities to protect, the follower acts next to reduce capacity from unprotected suppliers, and the firm then satisfies its demand using the remaining capacity. We formulate a three‐stage mixed‐integer program that is well‐suited to decomposition techniques and develop an effective cutting‐plane algorithm for its solution. The corresponding algorithmic approach solves a sequence of scaled and relaxed problem instances, which enables solving problems having much larger data values when compared to standard techniques. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

加强海军航空军械器材信息化建设的对策研究

面对现代空战时域、空域广阔,发生时机不确定性强,航空军械装备战损消耗大的局面,为达到海军航空军械器材保障"快速反应"和"精确保障"目的,必须进一步加强海军航空军械器材信息化建设的研究。首先从总体上规划了海军航空军械器材信息管理系统功能;然后研究了信息化管理的主要技术;最后,提出推行海军航空军械器材"全资可视化"管理,为海军航空军械器材信息化保障提供了一种建设思路和技术指导。     

航空维修活动中的组织知识存量

将知识管理的思想引入到航空维修中来,认为知识是构成维修活动的最基本要素,而知识存量的多少及应用的程度,反映在维修活动中就是维修能力的强弱.通过建立知识的增长模型,对构成航空装备维修的主要活动从知识的角度进行了分析,在此基础上建立了基于维修活动的航空维修组织知识存量度量模型,运用模糊综合评判的方法,给出了具体的算法步骤,最后通过算例进行具体分析,说明了该方法的有效性、实用性.     

To Be or Not To Be: The Development of Soviet Deck Aviation

Few issues were as contentious in the development of the Soviet Navy as the role of aircraft carriers and sea-based aviation. Despite the continued insistence by the highest naval authorities and scientific experts that surface combatants simply could not be protected in the open ocean without the support of ship-borne aviation, Soviet leaders – for a variety of reasons – resisted aircraft carrier development until the final decades of the Cold War. In examining one of the most defining and telling asymmetries of the Cold War at sea, the author argues that while the USSR was economically and technologically capable of building aircraft carriers of any class, bureaucratic infighting, misperceptions of cost and practicality, and the inherent flaws of a totalitarian system ultimately created an impossible gap in capabilities between the two sides. The priorities and direction of Soviet weapons and defense technology development during the Cold War was largely a factor of the military-political situation taking shape at home, and in the world. As a rule, the navy was assigned missions that corresponded to its capabilities at a given point in time, rather than the other way around. Often, the navy lacked the material resources needed to implement its core mission. The availability of these resources, in turn, depended on the country's economic situation, its scientific potential, the technological state of its industry, as well as the subjective influence of political and military leaders on the priorities of technological development. The impact of the country's socioeconomic imperatives was undoubtedly also felt in the sluggish pace of development of ship-borne aviation and aircraft carriers in the USSR.     

面向对象的反舰导弹航路规划

针对反舰导弹航路规划的任务特点,提出了一种面向对象的反舰导弹航路规划方法.在全面分析了反舰导弹航路规划中可能用到的类的基础上,建立了对各种类的描述,使得不同算法和不同任务要求的航路规划可以通过对类的继承和对成员函数的重载实现.最后,在VC 平台下,对这种面向对象的反舰导弹航路规划方法进行了编程实验.     

直升机吊放声纳搜索方法效能研究

利用直升机吊放声纳对潜艇目标进行搜索,是航空反潜作战的重要环节.引入蒙特卡罗法对吊放声纳搜潜方法进行效能评估,以概率和统计理论方法得出其搜索概率作为评定吊放声纳搜潜方法效能的指标.对三种吊放声纳搜潜方法进行了效能仿真.通过计算机模拟对三种方法对潜艇目标的搜索概率进行比较,结果表明采用蒙特卡罗法对吊放声纳搜潜方法进行效能评估是可行有效的.     

Investment in production resource flexibility: An empirical investigation of methods for planning under uncertainty

We examine several methods for evaluating resource acquisition decisions under uncertainty. Traditional methods may underestimate equipment benefit when part of this benefit comes from decision flexibility. We develop a new, practical method for resource planning under uncertainty, and show that this approach is more accurate than several commonly used methods. We successfully applied our approach to an investment problem faced by a major firm in the aviation information industry. Our recommendations were accepted and resulted in estimated annual savings in excess of $1 million (US). © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

A parallel machine replacement model

This paper considers a finite horizon parallel machine replacement problem where a fixed number of machines is in operation at all times. The operating cost for a machine goes up as the machine gets older. An older machine may have to be replaced by a new one when its operating cost becomes too high. There is a fixed order cost associated with the purchase of new machines. Machine purchase prices and salvage values may depend on the period in which they were purchased. The objective is to find a replacement plan that minimizes the total discounted cost over the problem horizon. We believe that the costs in our model are more commonly observed in practice than those previously used in the literature. The paper develops properties of optimal solutions and an efficient forward‐time algorithm to find an optimal replacement plan. A dominance property is developed that further limits the options to be considered, and a simple forecast horizon result is also presented. Future research possibilities are mentioned. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 275–287, 2002; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/nav.10012