Journal of the Operational Research Society

Namen, A A; Bornstein, C T; Rosenhead, J

doi: 10.1057/palgrave.jors.2602585pmid: N/A

AbstractThis paper presents some alternatives for the improvement of the conditions of life for poor communities based on self-management and sustainability in food production. A complex decision process is necessarily involved, and a soft OR approach, more specifically, robustness analysis, is used in its analysis. Some new features of the approach arise, not least from its community operational research context. A software called Robus has been developed which helps in the application of the methodology.

Zhang, X; Chakravarthy, A; Gu, Q

doi: 10.1057/palgrave.jors.2602581pmid: N/A

AbstractThis paper addresses the production and workforce scheduling problem under disruptions in United States Postal Service mail processing facilities. These facilities contain a large variety of equipment and employ a non-homogeneous workforce that work on shifts of various lengths and start times. Disruptions such as demand fluctuation and absenteeism happen and may significantly change demand and the size of workforce. How to adjust production plans and workforce schedules through the use of overtime and flexible employees in the face of these disruptions to meet the service commitment is a challenging problem yet to be solved. This problem is modelled as a large-scale integer program, which contains equipment scheduling, shift scheduling and overtime management, and break assignment modules. Problems of realistic size are solved efficiently through an LP-based decomposition algorithm. Comprehensive experiments have been designed to investigate the effects of the use of overtime, the control of absenteeism, and the importance of integrating equipment and workforce scheduling simultaneously. The model integrates seamlessly with other research studies and provides the necessary and critical tools to manage the resources in a facility on a routine basis.

Syntetos, A A; Babai, M Z; Dallery, Y; Teunter, R

doi: 10.1057/palgrave.jors.2602593pmid: N/A

AbstractIn this paper we propose a modification to the standard forecasting, periodic order-up-to-level inventory control approach to dealing with intermittent demand items, when the lead-time length is shorter than the average inter-demand interval. In particular, we develop an approach that relies upon the employment of separate estimates of the inter-demand intervals and demand sizes, when demand occurs, directly for stock control purposes rather than first estimating mean demand and then feeding the results in the stock control procedure. The empirical performance of our approach is assessed by means of analysis on a large demand data set from the Royal Air Force (RAF, UK). Our work allows insights to be gained on the interactions between forecasting and stock control as well as on demand categorization-related issues for forecasting and inventory management purposes.

Plà, L M; Faulín, J; Rodríguez, S V

doi: 10.1057/palgrave.jors.2602599pmid: N/A

AbstractHousing facilities design represents the main strategic decision in pig farms. This paper introduces a linear programming formulation of a semi-Markov process to approach the facilities design. Thus, the Linear Programming formulation determines the optimum replacement policy and provides the equilibrium distribution of the herd along pig facilities. Then, the calculation of the associated needs of room for each sow facility is derived from sow herd distribution at equilibrium. Results show the flexibility of the model for designing pig facilities and computational advantages in the solving procedure compared to previous proposals. Furthermore, the robustness of the optimal solution is studied by means of sensitivity analysis.

Wyburn, J; Hayward, J

doi: 10.1057/palgrave.jors.2602600pmid: N/A

AbstractOR methodology is applied to the contemporary concern of modelling language group interaction, with a view to language planning. The change in size of two unilingual language groups, and of a third bilingual population mediating the interaction of these, is modelled using system dynamics. The model is one of highest possible endogeneity, with the minimum of external intervention in modelling runs. The model is applied to the instances of modern Canada excluding Quebec, Quebec, all Canada and Wales, and conclusions drawn regarding the use of the model in determining language planning initiatives.

Lakhal, L

doi: 10.1057/palgrave.jors.2602601pmid: N/A

AbstractEffective quality improvement has become a potentially valuable way of securing competitive advantage and improving organizational performance. This research conceptualizes and develops a framework that links quality, competitive advantage, and organizational performance. Data for the study were collected from 74 organizations and the relationships proposed in the framework were tested using structural equation modelling. The results indicate that quality improvement can lead to enhanced competitive advantage and improved organizational performance. The contribution of the paper is that it provides empirical support for direct and indirect effects of quality on organizational performance and competitive advantage in Tunisia.

Tsao, H-Y; Lin, P-C; Pitt, L; Campbell, C

doi: 10.1057/palgrave.jors.2602564pmid: N/A

AbstractResearching customer retention rates is made difficult because of the lack of suitable systems with which to measure it. From a first-order Markov brand-switching model, serial equations are derived to estimate the retention rate using market share and loyalty. To explore the impact of loyalty and promotion programme on retention rate, data from five leading brands for three product categories were obtained to fit the developed model. Findings suggest that: (1) when the loyalty effect remains unchanged over a period of time, the greater the effect of a promotion programme, the greater the retention rate; (2) when the promotion effects among brands are similar, the retention rate varies depending on level of loyalty; and (3) when the proportion of loyal customers is high, the proportion of potential switchers affected by promotion programmes is low. In this case, the impact of a promotion programme on the retention rate is not significant. This model successfully demonstrates how the Markov brand-switching model can be employed to estimate a measure of retention rate from consumer panel data as well as to better understand how promotion affects loyalty, switching behaviour, and retention rate.

Thiel, D

doi: 10.1057/palgrave.jors.2602608pmid: N/A

AbstractOwing to the perishability of fresh produce, the food industry has to react quickly by implementing different policies on labour management. We conduct two intensive surveys which showed that human resource management (HRM) issues in the fresh food industry mainly consist in finding appropriate labour capacity that meets the specific fluctuations in sales. The HRM decisions were taken so that flexible working time more efficiently matched the workload and staffing numbers. These empirical findings are very informative in that they point to how managers make HRM decisions when choosing the kind of employees they have to hire according to the type of additional workload imposed. In addition, they relate to the employment contract (temporary or permanent staff, subcontractor), the time required for employees to be efficient and their quality of work. Following this qualitative research, we mathematically formalize the combinatory possibilities of HRM assignments and the decision problems to be addressed. Finally, we propose a simulation tool for analysing the dynamical consequences of the HRM policies by comparing different policies on labour management.

Zhang, B; Murali, P; Dessouky, M M; Belson, D

doi: 10.1057/palgrave.jors.2602596pmid: N/A

AbstractWe have developed a methodology for allocating operating room capacity to specialties. Our methodology consists of a finite-horizon mixed integer programming (MIP) model which determines a weekly operating room allocation template that minimizes inpatients' cost measured as their length of stay. A number of patient type priority (eg emergency over non-emergency patient) and clinical constraints (eg maximum number of hours allocated to each specialty, surgeon, and staff availability) are included in the formulation. The optimal solution from the analytical model is inputted into a simulation model that captures some of the randomness of the processes (eg surgery time, demand, arrival time, and no-show rate of the outpatients) and non-linearities (eg the MIP assumes proportional allocation of demand satisfaction (output) with room allocation (input)). The simulation model outputs the average length of stay for each specialty and the room utilization. On a case example of a Los Angeles County Hospital, we show how the hospital length of stay pertaining to surgery can be reduced.

Marianov, V; Boffey, T B; Galvão, R D

doi: 10.1057/palgrave.jors.2602606pmid: N/A

AbstractMost models for location of immobile congested facilities assume exponentially distributed service time at the facilities. Although the resulting formulations are tractable, they do not adequately represent service time distributions with small variances, as often occur in practice. In a recent paper, the authors utilized an order r Erlang distribution for the service time, applied to the simple case of single-server facilities. We generalize this approach to multiple-server facilities, which need a different mathematical treatment. The constraint on service availability is cast as a linear constraint on the proportion of time the servers are busy, and its right-hand side parameter is provided for different situations. Extensive analysis is offered on the influence of the parameters of the service time and the capacity of the facilities on the performance of the system. Numerical results are given for a data set relating to the municipality of Rio de Janeiro.