Sensor placement in active multistatic sonar networks

The idea of deploying noncollocated sources and receivers in multistatic sonar networks (MSNs) has emerged as a promising area of opportunity in sonar systems. This article is one of the first to address point coverage problems in MSNs, where a number of points of interest have to be monitored in order to protect them from hostile underwater assets. We consider discrete “definite range” sensors as well as various diffuse sensor models. We make several new contributions. By showing that the convex hull spanned by the targets is guaranteed to contain optimal sensor positions, we are able to limit the solution space. Under a definite range sensor model, we are able to exclude even more suboptimal solutions. We then formulate a nonlinear program and an integer nonlinear program to express the sensor placement problem. To address the nonconvex single‐source placement problem, we develop the Divide Best Sector (DiBS) algorithm, which quickly provides an optimal source position assuming fixed receivers. Starting with a basic implementation of DiBS, we show how incorporating advanced sector splitting methods and termination conditions further improve the algorithm. We also discuss two ways to use DiBS to find multiple source positions by placing sensors iteratively or simultaneously. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 287–304, 2017     

Resourcing for defense: Solving the roles and missions puzzle

One of the most important issues facing the post‐Cold War U.S. defense establishment concerns the future allocation of combat tasks and responsibilities among different branches of the armed forces. The challenge is to reduce unnecessary redundancy across roles and missions when resources are highly constrained, without compromising military effectiveness. Defining the policy problem as one of resource allocation rather than operational effectiveness, we develop a methodology for allocating roles and missions. Our methodology focuses at the highest level of force aggregation and uses a mathematical programming model to produce cross‐service cross‐mission trade‐offs that will yield the best total force combat and non‐combat potential within resource consumption constraints.     

Assessing regional security dialogue through the agent/structure lens: reflections on ACRS

Using insights from agent/structure dynamics, the authors highlight the interplay between social/ideational elements drawn from the international experience with arms control, and those that prevailed at the state/agent level, among participants in ACRS. At the agent level, they focus on Egypt and Israel, the major protagonists in the talks. Their analysis reveals implicit clashes that occurred among these different ideational dimensions, and their constraining impact on the ability of states to achieve agreement on cooperative security arrangements. They suggest that attention must be directed to these constraints in any attempt to reconvene the ACRS talks.     

Optimal source placement for point coverage in active multistatic sonar networks

The allocation of underwater sensors for tracking, localization, and surveillance purposes is a fundamental problem in anti-submarine warfare. Inexpensive passive receivers have been heavily utilized in recent years; however, modern submarines are increasingly quiet and difficult to detect with receivers alone. Recently, the idea of deploying noncollocated sources and receivers has emerged as a promising alternative to purely passive sensor fields and to traditional sonar fields composed of collocated sources and receivers. Such a multistatic sonar network carries a number of advantages, but it also brings increased system complexity resulting from its unusual coverage patterns. In this work, we study the problem of optimally positioning active multistatic sonar sources for a point coverage application where all receivers and points of interest are fixed and stationary. Using a definite range sensor model, we formulate exact methods and approximation algorithms for this problem and compare these algorithms via computational experiments. We also examine the performance of these algorithms on a discrete approximation of a continuous area coverage problem and find that they offer a significant improvement over two types of random sensor deployment.     

A realist before ‘realism’: Quincy Wright and the study of international politics between two World Wars

Contrary to conventional belief, IR theorist Quincy Wright and his cohort before World War II were neither idealists, legalists, nor moralists. Deeply grounded in the realism and pragmatism that marked the University of Chicago's interwar climate, Wright applied an ethically neutral and empirical approach to understanding international relations. Unlike the stereotypical interwar theorist, Wright eschewed legalism. He recognized that a struggle for power drove international politics and would continue to do so for the forseeable future. Above all, Wright embraced the complexities of international politics, rejecting monocausal explanations for war or simplistic frameworks for understanding international relations.