Bounds on parallel-processing of queues with multiple-phase jobs

Currently, both the hardware and software designs of many large computing systems aim at improved system performance through exploitation of parallelism in multiprocessor systems. In studying these systems, mathematical modelling and analysis constitute an important step towards providing design tools that can be used in building such systems. With this view the present paper describes a queueing model of a multiprocessor system operating in a job-shop environment in which arriving jobs consist of a random number of segments (sub-jobs). Two service disciplines are considered: one assumes that the sub-jobs of a given job are capable of parallel operation on different processors while the other assumes that the same sub-jobs must be operated in a strictly serial sequ'snce. The results (in particular, the mean number in the system and waiting time in queue) obtained for these two disciplines are shown to be bounds for more general job structures.     

A Revolution Too Far? US Defence Innovation,Europe and NATO’s Military-Technological Gap

The United States is launching another defence innovation initiative to offset the growing military-technological might of countries such as China, Russia and Iran. However, by utilising emerging technologies from the commercial sector to achieve greater military power the US may further open up the technology gap within NATO. This raises serious questions for NATO’s European allies. This article probes the nature of the US’s latest innovation strategy and sets it within the strategic context facing Europe today. Whether European governments, firms and militaries will join the US in its new defence innovation drive will hinge on politico-military and industrial considerations.     

Augmented nested sampling for stochastic programs with recourse and endogenous uncertainty

We propose a novel simulation‐based approach for solving two‐stage stochastic programs with recourse and endogenous (decision dependent) uncertainty. The proposed augmented nested sampling approach recasts the stochastic optimization problem as a simulation problem by treating the decision variables as random. The optimal decision is obtained via the mode of the augmented probability model. We illustrate our methodology on a newsvendor problem with stock‐dependent uncertain demand both in single and multi‐item (news‐stand) cases. We provide performance comparisons with Markov chain Monte Carlo and traditional Monte Carlo simulation‐based optimization schemes. Finally, we conclude with directions for future research.     

Dangerous work: Terrorism against U.S. diplomats

The goal of diplomats is to represent their countries’ interests through diplomacy, not arms. Because they are not military personnel, they may be perceived as at lower risk of being the target of terrorists. However, recent events have called this perception into question. Despite this danger, there has been little research on terrorist attacks against diplomats. Drawing on the terrorism studies literature, this article argues that diplomats are targeted more than non-diplomatic targets in countries where certain U.S. foreign policies are implemented. An empirical analysis of 471 attacks against U.S. diplomats from 1970 to 2011 reveals that while U.S. alliances and foreign aid increase the likelihood of attacks against diplomats, U.S. military intervention and civil war, on the other hand, increase the risk of terrorism against non-diplomatic targets. This finding is relevant because it shows terrorist attacks against diplomats result from certain types of foreign policy.     

Flintlock brass fittings from the 19th-century Akko 1 shipwreck,Israel

The Akko 1 shipwreck is the remains of a 26-metre-long Egyptian armed vessel or auxiliary naval brig built at the beginning of the 19th century. Remains of six flintlock muskets were retrieved from the shipwreck, and characterised by various metallurgical methods. The research aimed to study the composition and microstructure of the musket fittings and their manufacturing processes, and if possible, to determine the date and origin of the raw materials. The lead isotope analysis of the fittings suggests that their raw material originated in Great Britain. Based on their typology and composition, the fittings were made in Great Britain of brass alloy and manufactured by casting, probably at the same workshop; and the staple was manufactured by casting and drawing. Considering the zinc content, combined with the manufacturing techniques, the fittings were manufactured between the latter part of the 18th and the early 19th centuries, which might indicate that they were purchased in the course of 19th century weapons trade to be used on board the Egyptian ship.     

An algorithm for optimal shipments with given frequencies

This article deals with the problem of minimizing the transportation and inventory cost associated with the shipment of several products from a source to a destination, when a finite set of shipping frequencies is available. A mixed-integer programming model—shown to be NP-hard—is formulated for that problem. The computational complexity of some similar models applied to different problems is also investigated. In particular, whereas the capacitated plant location problem with operational cost in product form is NP-hard, the simple plant location problem with the same characteristics can be solved in polynomial time. A branch-and-bound algorithm is finally worked out, and some computational results are presented. © 1996 John Wiley & Sons, Inc.     

A sequential attribute sampling inspection game for item facilities

The routine inspection of facilities storing large numbers of identical items is modeled as a two‐person, sequential game. Timely detection of illegal activity is parameterized in terms of a critical time to detection, and equilibria are derived which provide inspection strategies. Necessary conditions for deterrence of illegal behavior are discussed. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 496–505, 2001     

Optimizing ship berthing

Ship berthing plans reserve a location for inbound U.S. Navy surface vessels prior to their port entrance, or reassign ships once in port to allow them to complete, in a timely manner, reprovisioning, repair, maintenance, training, and certification tests prior to redeploying for future operational commitments. Each ship requires different services when in port, such as shore power, crane, ordnance, and fuel. Unfortunately, not all services are offered at all piers, and berth shifting is disruptive and expensive: A port operations scheduler strives to reduce unnecessary berth shifts. We present an optimization model for berth planning and demonstrate it for Norfolk Naval Station, which exhibits all the richness of berthing problems the Navy faces. ® 1994 John Wiley & Sons, Inc.     

A stochastic machine maintenance and sale problem: Results with different production functions

In this article we solve and analyze a stochastic version of the Boiteux problem by employing the stochastic optimal control method. Our setup is close to that of Thompson [22]. Our focus is to analyze, under the same structure, how different production functions and how the variance in machine deterioration/maintenance affect our optimal machine maintenance and sale date decisions. © 1993 John Wiley & Sons, Inc.     

Application of the stein-chen method for bounds and limit theorems in the reliability of coherent structures

The Stein-Chen method for establishing Poisson convergence is used to approximate the reliability of coherent systems with exponential-type distribution functions. These bounds lead to quite general limit theorems for the lifetime distribution of large coherent systems. © 1993 John Wiley & Sons, Inc.