W e consider stochastic vehicle routing problems on a network with random travel and service times. A fleet of one or more vehicles is available to be routed through the network to service each node. Two versions of the model are developed based on alternative objective functions. We provide bounds on optimal objective function values and conditions under which reductions to simpler models can be made. Our solution method embeds a branch-and-cut scheme within a Monte Carlo sampling-based procedure.
We formulate and solve a mathematical programming optimization model to find a minimum cost solution for an orthogonal split‐spread design in a 3‐D land seismic survey. The model contains decision variables on source and receiver location spacings, the amount of receiver equipment, and the production rate of the seismic crews. The model includes operational constraints for source and receiver movements. It also includes geophysical constraints for fold coverage, offset, and azimuth. To demonstrate the efficacy of the model, we include an example and solve it using the nonlinear optimization solver in Microsoft Excel. The model results demonstrate the classic trade‐off between source and receiver points to satisfy the geophysical requirements. In addition, we conduct sensitivity analysis on an important production parameter: the maximum number of source points that can be shot per day. We show that although changes to this parameter do not impact the decision variables, such changes do have a significant effect on the total cost of the survey.
This paper describes a simulator for a large outdoor operation called a signal quality survey. Design and implementation of the simulator follows an object oriented approach with a primary focus of modeling operations cycles. The simulator is implemented in Visual C++/CSIM17. Excel acts as the primary user interface. A Microsoft Foundations Classes Single Document Interface application acts as a secondary user interface for simulation animation.We discuss the benefits of using discrete event simulation for this application. We also report on some of the challenges encountered during the implementation stages of the project.(causes damage to equipment), weather, permitting (i.e., permission to conduct the survey on public or private property), personnel problems, community relations, cultural factors, environmental and legal restrictions. Given the complexity of operations and the uncertainty associated with several of these factors, simulation was identified as an important decision support tool for use in understanding, quantifying, and improving signal quality survey operations.
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