The Medical System of Transportation deals with two online real-time decisions: ambulance dispatching and relocation. Dispatching consists of selecting which ambulance to send to an emergency call; relocation consists of determining how to modify the location of available ambulances in response to changes in the system’s state. Although the literature regarding this problem is extensive, only a limited number of online real-time approaches for ambulance management have been proposed, much less one taking into consideration different types of emergencies and vehicles. This paper proposes an online real-time matheuristic algorithm that combines: i) a new preparedness index defined as the availability probability of a multi-server queue model which is used as an optimization objective and as a control variable for relocation strategies, ii) two mathematical models to solve the relocation problem, one oriented to the maximization of coverage and other to the minimization of the maximum relocation time, and iii) two heuristic algorithms oriented to the maximization of the preparedness level, one to solve the dispatch problem and other to solve the location problem of one ambulance. The computational experiments, based on discrete event simulation and historical data of Bogotá, Colombia, have shown their capability to adequately respond to the necessities of real-time operation.

This article addresses the problem of dynamic sequencing on n identical parallel machines with stochastic arrivals, processing times, due dates and sequence-dependent setups. The system operates under a completely reactive scheduling policy and the sequence of jobs is determined with the use of dispatching rules. Seventeen existing dispatching rules are considered including standard and setup-oriented rules. The performance of the system is evaluated by four metrics. An experimental study of the system is conducted where the effect of categorical and continuous system parameters on the objective functions is examined. In light of the results from the simulation experiments, a parameterized priority rule is introduced and tested. The simulation output is analyzed using rigorous statistical methods and the proposed rule is found to produce significantly better results regarding the metrics of mean cycle time and mean tardiness in single machine cases. In respect to three machine cases, the proposed rule matches the performance of the best rule from the set of existing rules which were studied in this research for three metrics.

In this article, a manpower allocation and cell loading problem is studied, where demand is sto-chastic. The inter-cell and intra-cell movements are considered and attention is focused on as-signing operators with different skill levels to operations, because cell performance in addition to load cell is dependent on manpower. The purpose of this article is manpower allocation in cellu-lar manufacturing with consideration to learning and training policies. The manpower skill levels are determined in order to enhance production rate. The main contribution of this approach is the scenarios of training and learning in addition to the combination of training and learning being simulated. By using these three scenarios, the skill level of workers increase which reduces the processing time. In this regard cell layout is static where processing times and customer demand follow a normal distribution. As one of the significant costs of industrial unit is related to pro-duction cost, this study has attempted to reduce these costs by increasing the skill level of opera-tor which causes to reduce the processing time. Scenarios are evaluated by using a simulation method that finally attained results indicate this simulation provides better manpower assign-ments.

Operations research techniques have been used widely in simulating the dynamics of workforce systems. Discrete Event Simulation (DES) and System Dynamics (SD) are among the techniques that have been increasingly used in modelling military workforces. In the last five years, DES has seen more interest in modelling both career management and the training pipeline. Two significant reasons for this are discussed in this paper. This article presents some notes in comparing the two techniques in modelling military workforce. The study found that DES is an appealing method in workforce modelling, especially with a small size population, as it more easily accommodates new personnel attributes and prevents the fractionalisation of personnel through the system.