Scheduling a capacitated single machine with time deteriorating job values

We address the scheduling problem with the following characteristics: (i) there is a single machine available, (ii) the machine has limited capacity, and (iii) job value deteriorates with time. The problem is motivated from several real world situations, such as, downloading process of web pages, and scheduling of multiplexes. Since the problem is NP-hard, we propose new heuristics based on a multiplicative piece-wise metric as an approximation of the slope of job value deterioration. Computational results show that the proposed heuristics perform better than other existing heuristics for similar types of problems.     

Scheduling deteriorating jobs with CON/SLK due date assignment on a single machine

This paper considers the problem of scheduling deteriorating jobs and due date assignment on a single machine. The actual processing time of a job is a linear increasing function of its starting time. The problem is to determine the optimal due dates and the processing sequence simultaneously to minimize costs for earliness, due date assignment and weighted number of tardy jobs. We present polynomial-time algorithms to solve the problem in the case of two popular due date assignment methods: CON and SLK.     

Scheduling with processing set restrictions: PTAS results for several variants

We consider multiprocessor scheduling to minimize makespan. Each job has a given processing time and in addition, a subset of machines associated with it, also called its processing set. Each job has to be assigned to one machine in its set, thus contributing to the load of this machine. We study two variants of this problem on identical machines, the case of nested processing sets, and the case of tree-hierarchical processing sets. In addition, we consider uniformly related machines with a special case of inclusive processing sets, which has a clear motivation. We design polynomial time approximation schemes for these three variants. The first case resolves one of the open problems stated in the survey by Leung and Li (2008).     

Two-machine flow shop scheduling with deteriorating jobs and chain precedence constraints

In this paper we investigate two-machine flow shop scheduling problems with deteriorating jobs and chain precedence constraints. We consider two types of precedence constraints. Under the first type constraints, a successor cannot start on any machine before its predecessor has been completed on the same machine. Under the second one, a successor cannot start on any machine before its predecessor has been completed on all machines. We show that the problem with the first type precedence constraints is polynomially solvable, and the problem with the second type precedence constraints is NP-hard in the strong sense.     

A note: Multi-machine scheduling with general position-based deterioration to minimize total load

The majority of the papers dealing with scheduling deteriorating jobs ignores general deterioration forms, and considers only special cases. Moreover, most of these papers consider deterioration, most of these papers consider deterioration based on job starting times, and only a few study position-based deterioration. Finally, very few researchers focus on the measure of total load, which becomes important in a setting of deterioration on multi-machines. In this note, we study general, non-decreasing, job-dependent and position-dependent deterioration function. The machine setting is parallel identical machines, and the objective function is total load. We introduce a polynomial time solution for this problem.     

Unrelated parallel machine scheduling with setup consideration and a total weighted completion time objective

This paper addresses the problem of scheduling a set of independent jobs on unrelated parallel machines with job sequence dependent setup times so as to minimize a weighted mean completion time. The study of the problem stemmed from a real service industry problem. This problem is at least NP-hard in the ordinary sense, even when there are only two identical machines with no setups. Seven heuristic algorithms are proposed and tested by simulation. The results and analysis of quite extensive computational experiments are reported and discussed. The findings through the computational results are presented. Whether this problem is strongly NP-hard is left as an open question.     

Sourcing decisions of project tasks with exponential completion times: Impact on operating profits

When managing a project, a firm must evaluate multiple strategic factors and operational issues before deciding which tasks to keep in-house and which to outsource. We focus on one operational aspect of this evaluation process by examining the impact of different sourcing decisions of project tasks with exponential completion times on operating profits. As an initial attempt, we present two stylized models that capture two simplest types of projects: (a) a project with two “parallel” tasks that can be performed simultaneously and (b) a project with two “serial” tasks that must be performed sequentially. For each model, we determine the optimal operating profit for the case when the firm outsources zero task, one task, or two tasks. These operating profits can be informative for making sourcing decisions of different project tasks.     

Scheduling a maintenance activity and due-window assignment based on common flow allowance

We study a due-window assignment problem on a single machine. The job-dependent due-windows are obtained by the common flow allowance criterion. The scheduler has the option to perform a maintenance activity which is rate modifying, i.e., improves the processing times of the following jobs. We consider a number of versions of this setting: (i) The maintenance requires a constant time, (ii) The maintenance duration is an increasing function of its starting time (linear deterioration), and (iii) The maintenance duration is position-dependent (general deterioration). We study the standard setting of regular job processing times, and investigate also the extension to position-dependent processing times. The set of potential optimal positions for the maintenance activity is fully characterized. Consequently, the problems based on all the combinations of these settings are shown to be solved in polynomial time.     

Doing good deeds in times of need: a strategic perspective on corporate disaster donations

Major corporations often respond charitably in times of disaster. However, disasters can also impose nontrivial costs on firms themselves, and under adverse conditions, firms typically donate less, not more. This paper takes a strategic perspective on corporate magnanimity in times of crisis by looking at the relationship between firm value, reputation, and donations by U.S. Fortune 500 firms in the case of Hurricane Katrina. In general, we find that Katrina's landfall was associated with significant negative abnormal stock returns. In particular, we find that a reputation for social irresponsibility was associated with both the greatest drop in stock prices and the greatest likelihood of making a subsequent charitable donation in response to the disaster. Copyright © 2011 John Wiley & Sons, Ltd.     

Standard essential patents and global ICT value chains with a focus on the catching-up of China

Patents, standards and their combination, standard-essential patents (SEPs), are important in the information and communication technology (ICT) sector, in particular in mobile communication. We argue that SEPs are relevant in macroeconomic development and estimate the effect of a country's SEP portfolio on its value-added trade in global ICT value chains (GVC). We find that SEPs retain a higher share of value-adding domestically and that absorptive capacity is needed to join GVCs. China entered the SEP market late and is catching up rapidly. The trade effect of SEPs on China is different from that on matured economies because of the initially low value of its SEPs.     

The deterministic EOQ and EPQ with partial backordering at a rate that is linearly dependent on the time to delivery

Our original models for the EOQ and EPQ with partial backordering assumed that the backordering rate, β, is a constant. In this paper we extend those models to allow β to increase linearly as the time until delivery decreases. We show how those previous models can be adapted to find the optimal decision variable values for this new assumption and develop, for each model type, a condition that the initial value of β must meet for partial backordering to be optimal.