Quantifying the performance effects of idle time utilization in multiserver systems

In many practical multiserver queueing systems, servers not only serve randomly arriving customers but also work on the secondary jobs with infinite backlog during their idle time. In this paper, we propose a c‐server model with a two‐threshold policy, denoted by (e d), to evaluate the performance of this class of systems. With such a policy, when the number of idle servers has reached d (<c), then e (<d) idle agents will process secondary jobs. These e servers keep working on the secondary jobs until they find waiting customers exist in the system at a secondary job completion instant. Using the matrix analytic method, we obtain the stationary performance measures for evaluating different (e, d) policies. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007.     

Europe,Russia and the Ukraine crisis: the dynamics of coercion

This article analyses European strategy towards Russia during the Ukraine crisis between February 2014 and December 2015, conceptualising it as a coercive diplomatic strategy and analysing the relationship between its ends, ways and means. European strategy sought to reverse Russian intervention. However, this overarching aim was flanked by two ‘constraining’ aims of avoiding an escalation of the conflict and a breakdown of relations with Russia. The strategy shifted between these aims, which proved to be irreconcilable: while the EU partly succeeded in containing the conflict, it failed to reverse Russian intervention and relations between the EU and Russia deteriorated sharply.     

Optimal maintenance policies for a safety‐critical system and its deteriorating sensor

We consider the integrated problem of optimally maintaining an imperfect, deteriorating sensor and the safety‐critical system it monitors. The sensor's costless observations of the binary state of the system become less informative over time. A costly full inspection may be conducted to perfectly discern the state of the system, after which the system is replaced if it is in the out‐of‐control state. In addition, a full inspection provides the opportunity to replace the sensor. We formulate the problem of adaptively scheduling full inspections and sensor replacements using a partially observable Markov decision process (POMDP) model. The objective is to minimize the total expected discounted costs associated with system operation, full inspection, system replacement, and sensor replacement. We show that the optimal policy has a threshold structure and demonstrate the value of coordinating system and sensor maintenance via numerical examples. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 399–417, 2017     

“Effing” the military: a political misunderstanding of management

The use of commercial business management techniques is widespread in all government departments, including the Ministry of Defence. This article examines the use of popular management techniques in the Armed Forces and argues that their application is misplaced. It looks at what the “effs” – “efficiency” and “effectiveness” – mean in the business world and to the Armed Forces. It compares the definitions both in business and the Armed Forces and finds that there are few, if any, situations where the same measurements can be applied. Whilst many management techniques are suited for business, the function of the Armed Forces and its output cannot be measured in the same way, complicated by the different metrics of “efficiency” in peace and in war. This difference may not be clearly understood by some politicians, or indeed by some senior military personnel. Using examples from some of the most popular management techniques such as “Lean” and “Agile” it is possible to see that their use might actually diminish the capabilities of the Armed Forces when it comes to performing their principal role – the use of force to achieve political objectives.     

Country survey: military expenditure and defence policy in Norway 1970–2013

This article examines military expenditure and defence policy in Norway from 1970 to 2013. Until 1990 Norwegian military expenditure remained between 2.5 and 3.0 per cent of Gross Domestic Product (GDP). Despite constant GDP shares, the military expenditure could not sustain a large and properly armed mobilization army. The constant nominal defence budgets of the 1990s accentuated the Norwegian Armed Forces' underlying imbalance between tasks, structure and budget. Around year 2000, large organizational reforms were effectuated, in which costs, the number of man-years, and underlying imbalances between tasks, structure and budget were reduced. Military expenditure increased in nominal terms between 2003 and 2013, while real military expenditure remained practically constant.     

A sequential scheduling problem with impatient jobs

There are n customers that need to be served. Customer i will only wait in queue for an exponentially distributed time with rate λ_i before departing the system. The service time of customer i has distribution F_i, and on completion of service of customer i a positive reward r_i is earned. There is a single server and the problem is to choose, after each service completion, which currently in queue customer to serve next so as to maximize the expected total return. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 659–663, 2015     

美军在信息安全视野下利用社交媒体政策研究

近年来,美军逐步调整社交媒体政策,重视发挥其在公共事务、家庭服务以及塑造军队形象中的独特功能。从信息安全的角度出发,在分析美军社交媒体政策发展变化及其内在动因的基础上,总结出美军运用社交媒体所采取的信息安全措施。     

Into the black box? Technology sharing in major arms transfers and beyond

From the recipients’ perspective, arms transfers have, through the use of offsets, technology transfers, and industrial participation, become an opportunity to receive not only advanced weapons, but also technologies not otherwise available. How important are friendly relations for securing a military export order? To what extent do buyers demand advanced military or commercial technology and how are these demands accepted by the supplier? How does this influence smaller producers in relation to major producers? These questions are addressed by studying (a) the Joint Strike Fighter/F-35 by Lockheed Martin, USA, and the JAS-39 Gripen aircraft by Saab, Sweden, (b) the Medium Multi-Role Combat Aircraft competition in India for 126 combat aircraft, and (c) the Indian offset policy. In the final section, some long-term consequences are discussed.     

Technical note: Finite-time regret analysis of Kiefer-Wolfowitz stochastic approximation algorithm and nonparametric multi-product dynamic pricing with unknown demand

We consider the problem of nonparametric multi-product dynamic pricing with unknown demand and show that the problem may be formulated as an online model-free stochastic program, which can be solved by the classical Kiefer-Wolfowitz stochastic approximation (KWSA) algorithm. We prove that the expected cumulative regret of the KWSA algorithm is bounded above by where κ₁, κ₂ are positive constants and T is the number of periods for any T = 1, 2, … . Therefore, the regret of the KWSA algorithm grows in the order of , which achieves the lower bounds known for parametric dynamic pricing problems and shows that the nonparametric problems are not necessarily more difficult to solve than the parametric ones. Numerical experiments further demonstrate the effectiveness and efficiency of our proposed KW pricing policy by comparing with some pricing policies in the literature.     

Optimal control of an M/G/1 queue with impatient priority customers

An optimal operating policy is characterized for the infinite‐horizon average‐cost case of a single server queueing control problem. The server may be turned on at arrival epochs or off at departure epochs. Two classes of customers, each of them arriving according to an independent Poisson processes, are considered. An arriving 1‐customer enters the system if the server is turned on upon his arrival, or if the server is on and idle. In the former case, the 1‐customer is selected for service ahead of those customers waiting in the system; otherwise he leaves the system immediately. 2‐Customers remain in the system until they complete their service requirements. Under a linear cost structure, this paper shows that a stationary optimal policy exists such that either (1) leaves the server on at all times, or (2) turns the server off when the system is empty. In the latter case, we show that the stationary optimal policy is a threshold strategy, this feature being commonplace in most of priority queueing systems and inventory models. However, the optimal policy in our model is determined by two thresholds instead of one. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 201–209, 2001