A note on the influence of missing operations on scheduling problems

This paper attempts to resolve the existing confusion concerning missing operations. Scheduling problems are classified in two groups: (i) null-continuous (NC)—comprising the problems where an optimal schedule remains optimal on replacement of arbitrarily small processing times (existing operations) with zeros (missing operations); (ii) null-discontinuous (NDC)—comprising those problems which are not null-continuous.     

Equivalence relations in the theory of repetitive consumption

Preference for food in the function of the time since last consumption and total preference in the function of eating frequency are equivalent mathematical representations of attitudes governing food consumption. The observed and postulated properties of these functions imply a formal correspondence between preference maximizing and variety seeking behavior.     

Capacity expansion with lead times and autocorrelated random demand

The combination of uncertain demand and lead times for installing capacity creates the risk of shortage during the lead time, which may have serious consequences for a service provider. This paper analyzes a model of capacity expansion with autocorrelated random demand and a fixed lead time for adding capacity. To provide a specified level of service, a discrete time expansion timing policy uses a forecast error‐adjusted minimum threshold level of excess capacity position to trigger an expansion. Under this timing policy, the expansion cost can be minimized by solving a deterministic dynamic program. We study the effects of demand characteristics and the lead time length on the capacity threshold. Autocorrelation acts similarly to randomness in hastening expansions but has a smaller impact, especially when lead times are short. However, the failure either to recognize autocorrelation or to accurately estimate its extent can cause substantial policy errors. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

PH分布参数估计的确定性退火加速EM算法

针对连续PH分布参数估计标准EM算法迭代速度慢和初值敏感易陷入局部最优化的问题,首先引入逆温因子和加速因子两参数改进算法,提出了确定性退火加速EM算法;然后,进行了详细的理论推导,给出了PH分布参数估计的具体步骤;最后,利用算例对两类典型分布和一组某装备维修时间的实际数据进行拟合,验证了改进算法的全局最优性和较快的收敛速度,拟合效果和迭代加速情况也验证了该算法的有效性和通用性。     

Casualty Rates of US Military Personnel During the Wars in Iraq and Afghanistan

Abstract

In Operation Iraqi Freedom, which ended in August 2010, nearly 3500 hostile deaths occurred among US military personnel and 32,000 more were wounded in action (WIA). More than 1800 hostile deaths occurred during Operation Enduring Freedom (in and around Afghanistan) through 2014 and about 20,000 were WIA. A larger proportion of wounded personnel survived in Iraq and Afghanistan than during the Vietnam War, but the increased survival rates were not as high as some studies have asserted. The survival rates were 90.2% in Iraq and 91.6% in Afghanistan, compared with 86.5% in Vietnam. The casualty rates varied between the conflicts in Iraq and Afghanistan and before, during, and after the respective surges. Amputation rates are difficult to measure consistently, but I estimate that 2.6% of all WIA and 9.0% of medically evacuated WIA from the Iraq and Afghanistan theaters combined resulted in the major loss of a limb. Elevated non-hostile death rates (including deaths due to accidents, illnesses, homicides, or suicides) resulted in about 220 more deaths in Iraq and about 200 more deaths in Afghanistan than would have been expected in peacetime among populations of the size deployed to those two conflicts.     

Another manifestation of cyber conflict: attaining military objectives through cyber avenues of approach

Cyberspace is an avenue of approach through which a military force can attain objectives of value. Through these cyber avenues of approach, military forces can engage, vet, organize, and direct human agents to accomplish specific activities. Although the objectives of these activities could differ from traditional military objectives, they still have military relevance. This particular manifestation of cyber conflict is neither a new domain of war nor something outside of warfare. Rather, it can be viewed as an emerging avenue of approach in the larger context of military operations, auguring benefits in the integration of cyber activities with operations.     

Multilateral defense cooperation in the Indo-Asia-Pacific region: Tentative steps toward a regional NATO?

Some U.S. military leaders have asserted that the United States, Japan, Australia, and India and the Republic of Korea are developing multilateral defense cooperation to deter aggression and uphold norms much like North Atlantic Treaty Organization (NATO) has in Europe. Frequent military exercises and China’s threats to freedom of navigation (FoN) and North Korea’s nuclear missiles comprise the motive force for such cooperation. However, cooperation thus far has been trilateral and minimal, given divergent national interests and dispersed geopolitical locations. Cooperation among Japan, Republic of Korea (ROK), and the United States is increasing given the threat, but ROK’s public opinion is divided about Japan. Australia, Japan, and India have increased cooperation with the United States but are reluctant to conduct FoN operations with the United States to challenge China’s expansionism in the South China Sea. If China becomes more aggressive and blocks FoN or seizes territory, development toward an Asian NATO is possible.     

Simple paths with exact and forbidden lengths

We study new decision and optimization problems of finding a simple path between two given vertices in an arc weighted directed multigraph such that the path length is equal to a given number or it does not fall into the given forbidden intervals (gaps). A fairly complete computational complexity classification is provided and exact and approximation algorithms are suggested.     

Adjacency‐based local top‐down search method for finding maximal efficient faces in multiple objective linear programming

It is well‐known that the efficient set of a multiobjective linear programming (MOLP) problem can be represented as a union of the maximal efficient faces of the feasible region. In this paper, we propose a method for finding all maximal efficient faces for an MOLP. The new method is based on a condition that all efficient vertices (short for the efficient extreme points and rays) for the MOLP have been found and it relies on the adjacency, affine independence and convexity results of efficient sets. The method uses a local top‐down search strategy to determine maximal efficient faces incident to every efficient vertex for finding maximal efficient faces of an MOLP problem. To our knowledge, the proposed method is the first top‐down search method that uses the adjacency property of the efficient set to find all maximal efficient faces. We discuss this and other advantages and disadvantages of the algorithm. We also discuss some computational experience we have had with our computer code for implementing the algorithm. This computational experience involved solving several MOLP problems with the code.