Case Study Commentary and Analysis: The Moral Sword of Damocles

Case summary, by James Cook (Case Study Editor):

In the final issue of the 2015 volume of the Journal of Military Ethics, we published a case study entitled “Coining an Ethical Dilemma: The Impunity of Afghanistan’s Indigenous Security Forces”, written by Paul Lushenko. The study detailed two extra-judicial killings (EJKs) by Afghan National Police (ANP) personnel in an area stabilized and overseen by a US-led Combined Task Force (CTF). To deter further EJKs following the first incident, the CTF’s commander reported the incidents up his chain of command and used the limited tools at his disposal to influence local indigenous officials directly. Apparently, the ANP unit took no notice. In his commentary on the case study, Paul Robinson considered moral compromise in war more generally. Coalition troops in Afghanistan, for instance, have encountered not just EJKs but also sexual abuse of minors, killing of non-combatants, kidnapping, torture, and widespread corruption. What should the soldier on the ground do if indigenous personnel violate Laws of Armed Conflict (LOAC) with impunity? Refusing to serve will not right or prevent moral wrongs, while staying on to fight the good but futile fight will mire the soldier in moral compromise. “?… [S]oldiers faced with this dilemma have no good options. The systemic failings surrounding them mean that it is probable that nothing they do will help”. In a concluding note, I suggested that while an individual soldier may indeed have no good options, as Paul Robinson suggests, that soldier’s military and nation at large are obliged to do what they can. At least, they must keep to the moral high ground so as not to give indigenous security forces an excuse to misbehave, and determine the nature of crimes such as EJKs: are they outlaw acts or in fact endorsed by the indigenous culture and perhaps even government? Below Colonel Dave Barnes, himself a veteran of Operation Enduring Freedom, analyzes Paul Lushenko’s case study at “?…?the local, tactical level: If a commander is in this situation – where her unit witnesses an EJK or other war crime – what should she do?”     

Algorithms and heuristics for variable-yield lot sizing

We consider the multiperiod lot-sizing problem in which the production yield (the proportion of usable goods) is variable according to a known probability distribution. We review two economic order quantity (EOQ) models for the stationary demand continuous-time problem and derive an EOQ model when the production yield follows a binomial distribution and backlogging of demand is permitted. A dynamic programming algorithm for an arbitrary sequence of demand requirements is presented. Heuristics based on both the EOQ model and appropriate modification of the underlying perfect-yield lot-sizing policies are discussed, and extensive computational evaluation of these heuristics is presented. Two of these heuristics are then modified to include the notion of supply safety stock. The modified heuristics consistently produce near-optimal lot-sizing policies for problems with stationary and time-varying demands.     

Likelihood estimation for generalized mixed exponential distributions

The class of functions expressed as linear (not necessarily convex) combinations of negative exponential functions is dense in the set of all square integrable functions on the nonnegative reals. Because of this and resultant mathematical properties, linear combinations of exponential densities have excellent potential for wide application in stochastic modeling. This work documents the development and testing of a practical procedure for maximum-likelihood estimation for these generalized exponential mixtures. The algorithm offered for the problem is of the Jacobi type and guarantees that the result will provide a legitimate probability function of the prescribed type. Extensive testing has been performed and results are very favorable: convergence is rapid and the use of computer resources rather limited.     

四轴超精密车床的改进坐标驱动装置

带微进给方式步进电机的PC控制轴系驱动装置可生产光学质量的表面。超精密车床可生产诸如球体和非球体之类的集合体,其表面粗糙度≤5nmRa,可用于光学装置的反光镜或空气轴承转轴的超精密零件。     

Application of level crossing analysis to discrete state processes in queueing systems

In this paper we introduce a discrete state level crossing analysis and present some basic results and a key theorem of level crossings. We illustrate the fertility of the discrete state level crossing analysis by applying it to queueing systems with (i) bulk arrival, (ii) instantaneous feedback, (iii) limited waiting space, and (iv) to machine interference problems.     

A time series analysis of some interrelated logistics performance variables

This paper is a case study. We show how the powerful methods of time series analysis can be used to investigate the interrelationships between Alert Availability, a logistics performance variable, and Flying Hours, an operational requirement, in the presence of a major change in operating procedures and using contaminated data. The system considered is the fleet of C-141 aircraft of the U.S. Air Force. The major change in operating procedures was brought about by what is known as Reliability Centered Maintenance, and the contaminated data were due to anomalies in reporting procedures. The technique used is a combination of transfer function modeling and intervention analysis.     

Characterizations of the exponential distribution by higher-order gap

Suppose X₁,X₂, ?,X_n is a random sample of size n from a continuous distribution function F(x) and let X_1,n, ≦ X_2,n ≦ ? ≦ X_n,n be the corresponding order statistics. We define the jth-order gap g_i,j as g_i,j = X_i+j,n ? X_i,n, 1 ≦ i < n, 1 ≦ j ≦ n ? i. In this article characterizations of the exponential distribution are given by considering the distributional properties of g_k,n-k, 1 ≦ k ≦ n.     

Optimal maintenance models for systems subject to failure–A Review

This paper is a state-of-the-art review of the literature related to optimal maintenance models of systems subject to failure. The emphasis is on work appearing since the 1976 survey, “A Survey of Maintenance Models: The Control and Surveillance of Deteriorating Systems,” by W.P. Pierskalla and J.A. Voelker, published in this journal.     

Joint determination of optimum variable and attribute target means

This article considers the problem of joint control of attribute and variable quality characteristics of a given product. Items are acceptable if they meet the specifications for both types of quality characteristics at the same time. Otherwise, the items are sold as scrap at reduced prices. The objective is to determine simultaneously the target values for each characteristic so as to maximize the expected profit per item. Several item-by-item quality-inspection plans are formulated on the basis of various inspection strategies. These strategies are defined in terms of whether the inspection is to be carried out simultaneously for both characteristics, or sequentially, or whether inspection for one of the characteristics is to be ignored. All these plans are shown to differ in terms of their profitability. However, they all yield equivalent quality standards. A numerical example is provided to illustrate the application of these models.