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     

The keyhole satellite program

James S. Corum, The Roots of Blitzkrieg: Hans von Seeckt and German Military Reform. Lawrence, KS: University of Kansas Press, 1992. Pp.274, photos, biblio, index; $29.95. ISBN 0–7006–0541‐X.

G. M. Hall, Geopolitics and the Decline of Empire, Implications for United States Defence Policy. Jefferson, NC: McFarland &; Co., 1990. Pp.xii + 210, index; £22.50. ISBN 0–89950–538–4.

Eric Carlton, Occupation: The Policies and Practices of Military Conquerors. London: Routledge, 1992. Pp.viii + 198, biblio, index; £30. ISBN 0–415–05846–5.

Erik Goldstein, Wars and Peace Treaties, 1816–1991. London: Routledge, 1992. Pp.xx + 264, 19 maps, biblio, index; £40. ISBN 0–415–07822–9.

Marc D. Lax, Selected Strategic Minerals. Lanham, Maryland: University Press of America, 1992. Pp.xvii + 337, 15 illus, biblio, index; $48.50. ISBN 0–8191–8300–8.

Keith Krause, Anns and the State: Patterns of Military Production and Trade, Cambridge Studies in International Relations Vol.22. Cambridge: Cambridge University Press, 1992. Pp.xi + 299, 32 tables, 3 figures, biblio, index; £35. ISBN 0–521–39446–5.

Frank Barnaby, The Role and Control of Weapons in the 1990s. London: Routledge 1992. Pp.189, index; £30. ISBN 0–415–07667–3.

Manus I. Midlarsky (ed.), The Internationalization of Communal Strife. London: Routledge, 1992. Pp.xvii + 306, 10 figures and tables, index; £45. ISBN 0–415–08408–3.

Richard N. Haass, Conflicts Unending: The United States and Regional Disputes. New Haven, Connecticut: Yale University Press, 1992. Pp.xiv + 176, notes and index; $12 (paperback), $25 (hardback). ISBN 0–300–04555–7 and 15129–8.

Sean M. Lynn and Steven E. Miller (eds.), America's Strategy in a Changing World. Cambridge, MA and London, UK, The MIT Press, 1992. Pp.xvii + 398, 6 tables; £14.25. ISBN 0–262–62085–5.

Robert Cribb, Gangsters and Revolutionaries: The Jakarta People's Militia and the Indonesian Revolution, 1945–1949. Sydney: Asian Studies Association of Australia/Allen &; Unwin, 1991. Pp.xiii + 222, 4 photos, 2 maps, glossary, biblio, index; £12.95 (paperback). ISBN 0–04–301296–5.

Anton Lucas, One Soul, One Struggle: Region and Revolution in Indonesia. North Sydney: Asian Studies Association of Australia/Allen &; Unwin, 1992. Pp.xxvi + 301, 14 photos, 4 maps, glossary, biblio, index; £12.95 (paperback). ISBN 0–04–442249–0.     

Economic Competition and Nuclear Cooperation

The number of bilateral nuclear cooperation agreements surged during the “nuclear renaissance” of the past decade. This proliferation is only partially explained by the prevailing approaches that focus on strategic imperatives. To supplement these explanations, this study draws on neoliberal models of economic competition to posit that bilateral agreement negotiations also exhibit conditions of “uncoordinated interdependence” and maneuvering to gain market share. Case evidence suggests the contours of supplier state bids for civilian assistance are determined at least as much by considerations about economic competition as they are by positive strategic goals. In addition, this study identifies several cases of cooperation where there appears to be little or no strategic motive for export agreements. The study concludes that patterns of economic competition and the influence of peers in defined competitive spaces alter material payoffs and impact policies. It also identifies a surprising role for principled restraint in dampening strategic and economic competition in some dyads.     

An exact algorithm for the maximal covering problem

This article develops a robust, exact algorithm for the maximal covering problem (MCP) using dual-based solution methods and greedy heuristics in branch and bound. Based on tests using randomly generated problems with problem parameters similar to those in the existing literature, the hybrid approach developed in this work appears to be effective over a wide range of MCP model parameters. The method is further validated on problems constructed from three real-world data sets. The extensive computational study compares the new method with other existing exact methods using problems that are as big, or larger than, those used in previous work on MCP. The results show that the proposed method is effective in most instances of MCP. In particular, it is shown that bounding schemes using Lagrangian relaxation are effective on MCP as a method of obtaining both exact and heuristic solutions. © 1996 John Wiley & Sons, Inc.     

The reliability of a series system of repairable subsystems: A bayesian approach

Consider the problem of estimating the reliability of a series system of (possibly) repairable subsystems when test data and historical information are available at the component, subsystem, and system levels. Such a problem is well suited to a Bayesian approach. Martz, Waller, and Fickas [Technometrics, 30 , 143–154 (1988)] presented a Bayesian procedure that accommodates pass/fail (binomial) data at any level. However, other types of test data are often available, including (a) lifetimes of nonrepayable components, and (b) repair histories for repairable subsystems. In this article we describe a new Bayesian procedure that accommodates pass/fail, life, and repair data at any level. We assume a Weibull model for the life data, a censored Weibull model for the pass/fail data, and a power-law process model for the repair data. Consequently, the test data at each level can be represented by a two-parameter likelihood function of a certain form, and historical information can be expressed using a conjugate family of prior distributions. We discuss computational issues, and use the procedure to analyze the reliability of a vehicle system. © 1994 John Wiley & Sons, Inc.