New product introduction against a predator: A bilevel mixed‐integer programming approach

We consider a scenario with two firms determining which products to develop and introduce to the market. In this problem, there exists a finite set of potential products and market segments. Each market segment has a preference list of products and will buy its most preferred product among those available. The firms play a Stackelberg game in which the leader firm first introduces a set of products, and the follower responds with its own set of products. The leader's goal is to maximize its profit subject to a product introduction budget, assuming that the follower will attempt to minimize the leader's profit using a budget of its own. We formulate this problem as a multistage integer program amenable to decomposition techniques. Using this formulation, we develop three variations of an exact mathematical programming method for solving the multistage problem, along with a family of heuristic procedures for estimating the follower solution. The efficacy of our approaches is demonstrated on randomly generated test instances. This article contributes to the operations research literature a multistage algorithm that directly addresses difficulties posed by degeneracy, and contributes to the product variety literature an exact optimization algorithm for a novel competitive product introduction problem. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

Governance through brokerage: informal governance in post-civil war societies

There is currently a lack of knowledge about how elites rule post-civil war societies without strong state institutions. This paper argues that elites oftentimes overcome such institutional deficiencies by engaging in governance through brokerage. According to this perspective, elites outsource central state functions to influential broker figures. This is particularly true when dealing with war-affected groups that possess much violent agency. By functioning as social membranes, brokers can help elites and war-affected groups to redefine a new social contract. Liberia is employed as an example to illustrate the paper’s central arguments.     

A characterization of optimal base‐stock levels for a multistage serial supply chain

In this article, we present a multistage model to optimize inventory control decisions under stochastic demand and continuous review. We first formulate the general problem for continuous stages and use a decomposition solution approach: since it is never optimal to let orders cross, the general problem can be broken into a set of single‐unit subproblems that can be solved in a sequential fashion. These subproblems are optimal control problems for which a differential equation must be solved. This can be done easily by recursively identifying coefficients and performing a line search. The methodology is then extended to a discrete number of stages and allows us to compute the optimal solution in an efficient manner, with a competitive complexity. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 32–46, 2016     

On the application and extension of system signatures in engineering reliability

Following a review of the basic ideas in structural reliability, including signature‐based representation and preservation theorems for systems whose components have independent and identically distributed (i.i.d.) lifetimes, extensions that apply to the comparison of coherent systems of different sizes, and stochastic mixtures of them, are obtained. It is then shown that these results may be extended to vectors of exchangeable random lifetimes. In particular, for arbitrary systems of sizes m < n with exchangeable component lifetimes, it is shown that the distribution of an m‐component system's lifetime can be written as a mixture of the distributions of k‐out‐of‐n systems. When the system has n components, the vector of coefficients in this mixture representation is precisely the signature of the system defined in Samaniego, IEEE Trans Reliabil R–34 (1985) 69–72. These mixture representations are then used to obtain new stochastic ordering properties for coherent or mixed systems of different sizes. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

The concept of logistics derived from Clausewitz: All that is required so that the fighting force can be taken as a given

This article assesses the existing literature on logistics in war, concluding that there is no satisfactory conceptual definition of logistics. It proposes a concept of logistics derived from Clausewitz's theory of war to fill that void. This is presented as a derivation because Clausewitz's distinction between (1) the use of the fighting forces (tactics and strategy) and (2) all other activities in war that were required so that forces could be taken as a given. The latter, left unnamed by Clausewitz, corresponds to a concept of logistics that proves to be an analytical peer to Clausewitz's categories of politics, tactics and strategy.     

Crime facilitation purposes of social networking sites: A review and analysis of the ‘cyberbanging’ phenomenon

There have been growing claims in media circles and law-enforcement settings that street gangs and criminal groups are turning to Internet-based social networking sites for various reasons ranging from the showcasing of their images and exploits to the suspected recruitment of members. The present study investigates whether such a trend is, in fact, in place. The presence of street gangs on these Internet sites is referred to as cyberbanging. While there is some anecdotal evidence suggesting that gangs are turning to social networking sites, there is little available research on exactly how street gangs and criminal groups use the Internet. Our main argument is that gang culture is in many ways an individualized phenomenon and this feature ties in directly with recent assessments of the Internet as a setting that is governed by a process of networked individualism. This theoretical link between the individualized gang setting and the presence of gang members on social networking sites helps us understand why recruitment is improbable even in a context where people are openly diffusing their image and exploits to a growing number of Internet users. The empirical segment of this research adds to this general outlook. Based on a keyword search of over 50 street gang names, the three main social networking sites (Twitter, Facebook, and MySpace) were monitored for street gang presence. Results illustrate that gang presence on social networking sites is linked primarily to promoting a general gang or street culture through individual displays. In regard to the visitors to such sites, there is no evidence that they are being tricked or manipulated in any way. They are, however, showing their curiosity in regard to such groups and, for those who share their comments and opinions, signs of support are evident. Thus, whereas criminal gangs are not proactively using the Internet to convert anyone into being gang members, social networking sites are creating a new venue for people who share or are sensitive to the values underlying street gang lifestyle to come together. These sites essentially create a new convergence setting for gang members to interact with a wider number of people who would probably never have been exposed to their lifestyles and exploits through physical interactions. The study's conclusion extends these findings toward further research in this area, as well as outlining the more relevant implications for law-enforcement monitoring of this growing phenomenon.     

DETERMINING THE DEFENCE INDUSTRIAL BASE

This paper models the determination of the defence industrial base – the number of different military systems a country decides to maintain. High R&D costs means that few countries can afford to produce major weapons systems and the producers also import systems. Non‐producers rely on imports and we assume their demand is driven by regional arms races. Military capability is determined by the number of systems and the quantity and quality of each. We examine how the defence industrial base is influenced by military expenditures, R&D costs, export controls, the nature of regional arms races and a variety of other factors.     

COUNTRY SURVEY XX: DEFENCE SPENDING AND PEACEKEEPING IN URUGUAY

Uruguay is a country with a very unusual profile, since it has just 3.4 million inhabitants but is among the top ten troop contributors to the UN PKO (Peace Keeping Operations) and is the first contributor per capita. In 2002 and 2003 it was the seventh troop contributor to the UN, and by the end of 2005 it was eighth in the UN ranking. Uruguay has never had any imminent external threat to its security after its independence in 1828, and it has had no internal threat since the end of the urban guerrillas’ actions in the 1970s. The country has no defence industry, and has always had an all‐volunteer military service, which presently involves almost 1% of the total population, and about 2% of the labour force. The empirical evidence presented in this paper shows that, in the past decades, Uruguayan defence spending has been influenced mainly by internal factors, most of them of an economic nature. The high participation in PKO has not increased military expenditure and it has produced a positive impact on the country’s economy.     

EFFECTS OF MILITARY SPENDING ON THE PROFITABILITY OF SPANISH DEFENCE CONTRACTORS

The traditional view of the defence industry obtaining large profits from contracts with the Ministry of Defence relies on several assumptions. Among these are the use of such arrangements as an instrument of industrial policy, the strong market power enjoyed by prime contractors, and the inefficiency encouraged by the sector. The findings show that defence contracts have a positive effect on profits, as well as the prizes for innovation and the market power enjoyed by some defence subsectors.     

A PRODUCTIVITY AND EFFICIENCY ANALYSIS OF THE SECURITY AND DEFENCE TECHNOLOGICAL AND INDUSTRIAL BASE IN SPAIN

This study analyses the performance of the productivity of the main industrial subsectors composing the security and defence technological and industrial base (SDTIB) in Spain from 1996 to 2009. Accordingly, we have used the non-parametric data envelopment analysis and bootstrapping techniques to compute Malmquist productivity indexes that allow us to split productivity growth into efficiency change and technical progress. The results obtained show productivity improvement in the SDTIB as a whole due mainly to advances in technology and to a lesser extent to the contribution of technical efficiency. The bootstrap approach yields further evidence, as for many cases, productivity growth or decline, is not statistically significant. This is the first time a study of this kind has been carried out on the production process of this sector in Spain.