Optimal path finding in direction,location, and time dependent environments

This article examines optimal path finding problems where cost function and constraints are direction, location, and time dependent. Recent advancements in sensor and data‐processing technology facilitate the collection of detailed real‐time information about the environment surrounding a ground vehicle, an airplane, or a naval vessel. We present a navigation model that makes use of such information. We relax a number of assumptions from existing literature on path‐finding problems and create an accurate, yet tractable, model suitable for implementation for a large class of problems. We present a dynamic programming model which integrates our earlier results for direction‐dependent, time and space homogeneous environment, and consequently, improves its accuracy, efficiency, and run‐time. The proposed path finding model also addresses limited information about the surrounding environment, control‐feasibility of the considered paths, such as sharpest feasible turns a vehicle can make, and computational demands of a time‐dependent environment. To demonstrate the applicability and performance of our path‐finding algorithm, computational experiments for a short‐range ship routing in dynamic wave‐field problem are presented. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

Airpower in India's 1999 Kargil War

For 74 days in mid-1999, India waged an intense war against intruding Pakistani forces on the Indian side of the Line of Control dividing Kashmir in the Himalayas. The Indian Air Force (IAF) was a key contributor to India's eventual victory in that war. Among other things, the IAF's combat performance showed how the skillful application of air-delivered firepower, especially if unmatched by the other side, can shorten and facilitate the outcome of an engagement that might otherwise have persisted indefinitely. It also showed that a favorable position in the conventional balance remains strategically useful even in conditions of mutual nuclear deterrence.     

Britain's Great Security Mirage: The Royal Navy and the Franco-Russian Naval Threat, 1898–1906

This article focuses on the relationship between the threat perception analyses of the British Admiralty and the strategic orientation of the Royal Navy at the outset of the twentieth century. The current view is that this was an era when fear of France and Russia drove British naval policy. However, as this article will show, Britain's Naval Intelligence Department formed a low opinion of French and Russian naval capabilities at this time and this negative evaluation exerted considerable influence over decision making. The belief that, owing to multiple qualitative deficiencies, these powers could definitely be beaten in battle lessened the standing of the Franco-Russian naval challenge and freed the Admiralty to consider the danger posed by other possible enemies, most notably Germany.     

Why Culture Matters: Revisiting the Sino-Indian Border War of 1962

This article examines the nuclear command and control (C²) system implemented in Pakistan since 1998, and discusses its potential consequences for the risk of inadvertent or unauthorised use of nuclear weapons. I argue that troubled civil-military relations and Pakistan's doctrine of ‘asymmetric escalation’ account for the creation of a command and control system with different characteristics during peacetime and military crises. Although the key characteristics of Pakistan's nuclear C² system allow relatively safe nuclear operations during peacetime, operational deployment of nuclear weapons during military standoffs is likely to include only rudimentary protections against inadvertent or unauthorised nuclear release. The implication of this study is that any shift from peacetime to wartime command and control procedures is likely to further destabilise Indo-Pakistani relations during the early stages of a diplomatic or military standoff, and introduce a non-trivial risk of accidental escalation to the nuclear level.     

Statistical equivalency and optimality of simple step‐stress accelerated test plans for the exponential distribution

Accelerated life testing (ALT) is commonly used to obtain reliability information about a product in a timely manner. Several stress loading designs have been proposed and recent research interests have emerged concerning the development of equivalent ALT plans. Step‐stress ALT (SSALT) is one of the most commonly used stress loadings because it usually shortens the test duration and reduces the number of required test units. This article considers two fundamental questions when designing a SSALT and provides formal proofs in answer to each. Namely: (1) can a simple SSALT be designed so that it is equivalent to other stress loading designs? (2) when optimizing a multilevel SSALT, does it degenerate to a simple SSALT plan? The answers to both queries, under certain reasonable model assumptions, are shown to be a qualified YES. In addition, we provide an argument to support the rationale of a common practice in designing a SSALT, that is, setting the higher stress level as high as possible in a SSALT plan. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Partial input to output impacts in DEA: Production considerations and resource sharing among business subunits

Data envelopment analysis (DEA) is a methodology for evaluating the relative efficiencies of peer decision‐making units (DMUs), in a multiple input/output setting. Although it is generally assumed that all outputs are impacted by all inputs, there are many situations where this may not be the case. This article extends the conventional DEA methodology to allow for the measurement of technical efficiency in situations where only partial input‐to‐output impacts exist. The new methodology involves viewing the DMU as a business unit, consisting of a set of mutually exclusive subunits, each of which can be treated in the conventional DEA sense. A further consideration involves the imposition of constraints in the form of assurance regions (AR) on pairs of multipliers. These AR constraints often arise at the level of the subunit, and as a result, there can be multiple and often inconsistent AR constraints on any given variable pair. We present a methodology for resolving such inconsistencies. To demonstrate the overall methodology, we apply it to the problem of evaluating the efficiencies of a set of steel fabrication plants. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Rethinking Stability in South Asia: India,Pakistan, and the Competition for Escalation Dominance

India and Pakistan are currently engaged in a competition for escalation dominance. While New Delhi is preparing for a limited conventional campaign against Pakistan, Islamabad is pursuing limited nuclear options to deter India. Together, these trends could increase the likelihood of nuclear conflict. India, for example, might conclude that it can launch an invasion without provoking a nuclear reprisal, while Pakistan might believe that it can employ nuclear weapons without triggering a nuclear exchange. Even if war can be avoided, these trends could eventually compel India to develop its own limited nuclear options in an effort to enhance deterrence and gain coercive leverage over Pakistan.     

An alliance between Cyprus and Greece: assessing its partners’ relative security contribution

The issue that this paper tackles is the assessment of the relative security benefits that Cyprus and Greece derive in the context of their cooperation on defence matters. This form of cooperation, known as the ‘Integrated Defence Space Doctrine’, aims at defending their interests in the Aegean Sea and the broader East Mediterranean theatre. The paper relies heavily on earlier research on this topic, which deals with the Greek–Cypriot alliance facing an arms race against Turkey, and uses a coefficient especially designed to assess the optimal levels of security and the associated defence expenditure of the two allies. A comparison of the relative security coefficient values for the two allies suggests that the security benefit that Greece derives thanks to its alliance with Cyprus exceeds the corresponding Cypriot benefit by far. Given the importance assigned to human resources by this index, in conjunction with the demographic problems of Greece, this conclusion justifies the recent Greek defence policy revision, emphasizing quality, capital equipment and flexibility of forces. This revision aims at satisfying the security requirements of the alliance and the increasing demands of an arms race against Turkey.