The performance of a call center is sensitive to customer abandonment. In this survey paper, we focus on G / GI / n + GI parallel-server queues that serve as a building block to model call center operations. Such a queue has a general arrival process (the G), independent and identically distributed (iid) service times with a general distribution (the first GI), and iid patience times with a general distribution (the +GI). Following the square-root safety staffing rule, this queue can be operated in the quality- and efficiency-driven (QED) regime, which is characterized by large customer volume, the waiting times being a fraction of the service times, only a small fraction of customers abandoning the system, and high server utilization. Operational efficiency is the central target in a system whose staffing costs dominate other expenses. If a moderate fraction of customer abandonment is allowed, such a system should be operated in an overloaded regime known as the efficiency-driven (ED) regime. We survey recent results on the many-server queues that are operated in the QED and ED regimes. These results include the performance insensitivity to patience time distributions and diffusion and fluid approximate models as practical tools for performance analysis.

Extant studies of cooperative advertising mainly consider a single-manufacturer-single-retailer channel structure. This can provide limited insights, because a manufacturer, in real practices, usually deals with multiple retailers simultaneously. In order to examine the impact of the retailer’s multiplicity on channel members’ decisions and on total channel efficiencies, this paper develops a multiple-retailer model. In this model, the manufacturer and the retailers play a Stackelberg game to make the optimal advertising decisions. Based on the quantitative results, it is observed that: 1) When there are multiple symmetric retailers, as the number of retailers scales up, the manufacturer’s national advertising investment contributes increasingly to add to channel members’ profits in equilibrium, but the total channel efficiency deteriorates quickly and converges down to a certain value; 2) When there are multiple asymmetric retailers, the distribution channel suffers from the manufacturer’s uniform participation strategy due to the retailer’s free-riding, and benefits with the manufacturer’s retailer-specific participation strategy. This study derives equilibrium solutions in closed form for all games considered and measures explicitly the gains/losses of channel efficiencies under different game settings.

A multiple criteria decision analysis (MCDA) approach is designed for capturing the relative preference information of a decision maker involved in a conflict. More specifically, an MCDA approach based on the outranking method, ELECTRE III, is employed for ranking states or possible scenarios in the conflict from most to least preferred, where ties are allowed, for a decision maker according to his or her value system. To demonstrate how this preference elicitation methodology can be conveniently implemented in practice within the framework of the Graph Model for Conflict Resolution, it is applied to a real world water supply crisis which occurred in the town of North Battleford, located in the Canadian province of Saskatchewan.

In this paper, we use the variational method to study the efficiency loss of user equilibrium for the multi-class, multi-criterion traffic equilibrium with general tolls and a discrete set of value of time. By introducing three important parameters ters k ₁, k ₂, k ₃, we derive several bounds of price of anarchy for this problem when tolls are considered and not considered as part of the system cost, with the cost-based criterion.

Lanchester equations and their extensions are widely used to calculate attrition in warfare models. The current paper addresses the warfare command decision-making problem for winning when the total combats capability of the attacking side is not superior to that of the defending side. For this problem, the corresponding warfare command stratagems, which can transform the battlefield situation, are proposed and analyzed quantitatively by considering the influence of the warfare information factor. The application examples in military conflicts show the feasibility and effectiveness of the proposed model and the warfare command stratagems for winning. The research results may provide a theoretical reference for warfare command decision making.

Elementary siphons are useful in the development of a deadlock prevention policy for a discrete event system modeled with Petri nets. This paper proposes an algorithm to iteratively extract a set of elementary siphons in a class of Petri nets, called system of simple sequential processes with resources (S3PR). At each iteration, by a mixed-integer programming (MIP) method, the proposed algorithm finds a maximal unmarked siphon, classifies the places in it, extracts an elementary siphon from the classified places, and adds a new constraint in order to extract the next elementary siphon. This algorithm iteratively executes until no new unmarked siphons can be found. It finally obtains a unique set of elementary siphons and avoids a complete siphon enumeration. A theoretical analysis and examples are given to demonstrate its efficiency and practical potentials.