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.     

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.     

The roles of service encounters, service value, and job satisfaction in achieving customer satisfaction in business relationships

Along with variables like the service process, perceived service value and customer satisfaction, job satisfaction of service employees plays a vital role in customer evaluation of service result. However, there has been little in-depth research into the nature of this relation, in particular in the context of B2B relations. In the sphere of an organization providing financial intermediation services to the banking sector and on the basis of a literature review, hypotheses are developed which establish the mediator role of service value and the moderator role of job satisfaction of service employees when delimiting customer satisfaction. Reliability and validity analysis give satisfactory results and our conclusions establish firstly that service encounter directly and significantly affects perceived service value which is the final antecedent to customer satisfaction and secondly, that the level of employment satisfaction moderates its effect on service value.     

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).     

Boundary spanner multi-faceted role ambiguity and burnout: An exploratory study

Although researchers have gained considerable knowledge regarding the multi-faceted manifestation of burnout over recent years, inconsistent findings of role ambiguity as an antecedent to burnout are still prevalent. Given the complex boundary-spanning nature of sales, it is likely that global measures of role ambiguity fail to fully capture the domain and impact of role ambiguity. To help address this gap, this study provides initial evidence that facets of role ambiguity impact burnout manifestation in the sales role differently. Specifically, findings provide a foundation to help mitigate the negative impact of burnout by focusing on only certain facets of role ambiguity.     

Airline Schedule Competition

This paper presents a simple model of airline schedule competition that circumvents the complexities of the spatial approach used in earlier papers. Consumers choose between two duopoly carriers, each of which has evenly spaced flights, by comparing the combinations of fare and expected schedule delay that they offer. In contrast to the spatial approach, the particular departure times of individual flights are thus not relevant. The model generates a number of useful comparative-static predictions, while welfare analysis shows that equilibrium flight frequencies tend to be inefficiently low.     

The joint replenishment and freight consolidation of a warehouse in a supply chain

We have developed joint replenishment and consolidated freight delivery policies for a third party warehouse that handles multiple items, which have deterministic demand rates in a supply chain. Two policies are proposed and mathematical models are developed to obtain the optimal parameters for the proposed policies. Four efficient algorithms are presented to solve the mathematical models for the two policies. The performances of the two policies with the parameters obtained from the proposed algorithms are then compared with the common cycle approach for 1600 randomly generated problems. The results show the robust performance of the proposed algorithm for both policies.     

Job rotation in assembly lines employing disabled workers

In this paper we consider the programming of job rotation in the assembly line worker assignment and balancing problem. The motivation for this study comes from the designing of assembly lines in sheltered work centers for the disabled, where workers have different task execution times. In this context, the well-known training aspects associated with job rotation are particularly desired. We propose a metric along with a mixed integer linear model and a heuristic decomposition method to solve this new job rotation problem. Computational results show the efficacy of the proposed heuristics.     

Coordination of planning and scheduling decisions in global supply chains with dual supply modes

We address the problem of coordinating aggregate planning decisions and short-term scheduling decisions in supply chains with dual supply modes. We consider long lead time, less expensive sea shipments that are based on demand forecast, and responsive but costly air shipments that are based on revised forecast closer to the demand period. The planning problem determines the sea shipment order quantity and inventory level, while the scheduling model determines the schedule and quantity of air shipments. Results from our numerical experiments suggest that our model leads to consistent cost improvements over a wide range of operating scenarios.     

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.     

Trust and forms of capital in business-to-business activities and relationships

The IMP group's ARA model, with its emphasis on interaction, captures social and economic dimensions of exchanges. We draw on it to compare three cases and assess how actors act in skilful and nuanced ways in mobilizing resources, given the very different norms of social and economic capital. We prioritize action ahead of structure and, given the inherent uncertainties that actors encounter in connection with resources, argue that trust is a cognitive and heuristic dimension of action, distinct from resources, actor-bonds and social capital. We conclude that for business practice, managers should be mindful that in order to trust others, they need to act in the distinct realms of social and economic capital, tempting though it is to interpret and measure the costs of actions economically.     

The effects of emotional intelligence on job performance and life satisfaction for the research and development scientists in China

To demonstrate the utility of the emotional intelligence (EI) construct in organizational studies, this study focuses on the effect of EI on job performance among research and development scientists in China. We argue that EI is a significant predictor of job performance beyond the effect of the General Mental Ability (GMA) battery on performance. This predictor effect is supported by results on a study of research and development scientists working for a large computer company in China. Our results also show that a self-reported EI scale developed for Chinese respondents, the WLEIS, is a better predictor of job performance than the scale developed in the U.S., the MSCEIT. Implications of the findings are discussed.

Diversification and sophistication of livestock products: The case of African countries

This study assesses the level of sophistication of livestock products in Africa by evaluating technology intensity and economic complexity of each product. Using trade data from 1995 to 2012, livestock commodity exports are classified based on technology intensity. Employing a method of reflection in computing the economic complexity of export products, we find that one fifth of African livestock commodity exports are manufactured with low technology while the rest is composed of raw materials. The results also show that the ten most complex livestock commodities represent about a third of African livestock total exports while the world level is almost double this figure. Yet African countries spend a huge share of their wealth on importing complex products. The results imply that by exporting non-complex products Africa loses nearly a third of the total value of its livestock exports. To boost the value of livestock products, African countries should exploit their untapped potential while securing the domestic market to achieve import substitution. This can be done by integrating with global value chains or developing niche markets at the regional or international markets and improving productive capabilities.     

Inventory control in a two-level supply chain with risk pooling effect

We consider an inventory control problem in a supply chain consisting of a single supplier, with a central distribution center (CDC) and multiple regional warehouses, and multiple retailers. We focus on the problem of selecting warehouses to be used among a set of candidate warehouses, assigning each retailer to one of the selected warehouses and determining replenishment plans for the warehouses and the retailers. For the problem with the objective of minimizing the sum of warehouse operation costs, inventory holding costs at the warehouses and the retailers, and transportation costs from the CDC to warehouses as well as from warehouses to retailers, we present a non-linear mixed integer programming model and develop a heuristic algorithm based on Lagrangian relaxation and subgradient optimization methods. A series of computational experiments on randomly generated test problems shows that the heuristic algorithm gives relatively good solutions in a reasonable computation time.     

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.