4. Conclusions and recommendations
In this paper we demonstrated a methodology for modifying the existing CRE structure. Our multiobjective approach maximizes the use of the existing structure, defines trade-offs between competing objectives, and significantly reduces the set of alternatives to consider. We demonstrated that in the absence of resource constraints, we can improve coverage by more than 15%, approximately 49 million people. Furthermore, with only 23 unit relocations (less than a 30% modification of the entire structure) coverage will exceed 98%, an improvement of an additional 45 million people covered. Finally, we demonstrated that the enforcement of the CCP constraint reduces the risk of an LSE neutralizing CRE assets and improves redundancy of coverage.
Potential improvements to our model merit further study. First, our use of county-based network Epigenetics Compound Library the Continental U.S. population to 3109 possible locations, which may overly simplify the number of possible facility locations. Counties also vary greatly in size, resulting in nodes in our network model representing varying area sizes. One possible alternative to county-level aggregation is to establish a network with population nodes corresponding to postal zip codes, which entail over 40,000 nodes. Whereas this expansion of the instance size would provide result in a network having a higher granularity representation of the population, it also would increase the complexity of the problem, which would likely preclude the use of an exact solution method and require the development of a customized heuristic. Second, our model assumed that a CRE unit could be relocated to any node (i.e., county) in the network. Depending on the availability of real estate and facilities to base such units, a modeling extension might consider a modification of possible facility locations to only consider sites predetermined by a governing authority. Finally, it merits mention that societies are not egalitarian; some population areas merit a higher level of protection due to their contribution to critical sectors of a national economy and/or governance, as these locations are more likely to incur a CBRN attack. As such, a modeling extension should also examine a third objective: minimizing either the average or the maximum response time for a subset of CBRN targets that are weighted by importance. Thus, the resulting model would seek to balance service quality to priority nodes, total coverage, and the cost of changing the existing enterprise unit locations.
AcknowledgmentThe authors gratefully thank the Area Editor, the Associate Editor, and two reviewers for their constructive comments that have helped improve the presentation of this paper.Disclaimer. The views expressed in this paper are those of the authors and do not reflect the official policy or position of the United States Air Force, the United States Army, the Department of Defense, or the United States Government.
OR in service industries; Employee scheduling; Integer programming; Flexible contract; Flexible service demand
Efficient management of workforce is one of the most important concerns in both manufacturing and service organizations, since it has a direct effect on the productivity of day-to-day operations and the quality of the service provided. Especially the employee scheduling problem has attracted considerable amount of research due to high costs associated with employee utilization. Employee scheduling problem is NP-Hard , and this, by itself, indicates a major challenge. However, in addition to this major challenge, concerns like large number of strict rules and regulations set by governments and labor unions, which impose hard constraints over the feasible utilization of employees, and non-numerical objectives such as well-being and happiness of the employees, and fairness between employees makes the problem even more interesting as a research topic.
In this study, we investigate an employee scheduling problem that we frequently face in a group of special health-care organizations, such as care centers for children with disabilities and nursing homes for elderly. Operating environment of these special organizations involves two basic forms of flexibility. The first flexibility is in the demand for services rendered in these organizations. The types of patients served require special personalized care. Timing, content and length of services vary significantly, and it is virtually impossible to generate a balanced pattern of services for a prolonged period of time. Services such as emergency health-care, social events, and educational activities that need case specific resources (personnel and equipment) in an irregular manner must be provided regularly. The second flexibility is in the availability of human resources that is utilized in the delivery of these highly flexible services. The span of skills required is very large, and consequently, it is almost impossible to have full time contracts with all the required human personnel. Hence, these health-care organizations need to provide a set of flexible services using employees with flexible contracts in addition to regular full time employees.
4. Conclusions and recommendations