At a cross docking terminal, inbound shipments are directly transshipped across the terminal to designated outbound trucks, so that delays and inventories are kept as low as possible. We consider an operational truck scheduling problem, where a dock door and a start time has to be assigned to each inbound truck. A set of outbound trucks is scheduled beforehand and, therefore, departure times are fixed. If a shipment is not unloaded, transshipped to the outbound gate and loaded onto the designated outbound truck before its departure we consider the shipments's value as lost profit. The objective is to minimize total lost profit. The paper at hand formalizes the resulting truck scheduling problem. We settle its computational complexity and develop heuristics in order to tackle the problem. We show the efficiency of these heuristics by means of a computational study. Last but not least, a case study is presented.
This chapter discusses a simulation model for conducting workload analyses of police forces. Due to the high operational heterogeneity and variability, determining reliable profiles for resource utilization and establishing their relationship to response times is a challenging task in and of itself that requires an adequate consideration of several sources of stochastic influence. Prior approaches from police practice mainly consider static ratios (e.g. resources per number of inhabitants or calls for service) in order to estimate capacity demand. Based on an extensive dataset comprising more than two million data points, we derive stochastic process models for all relevant police operations in a major metropolitan area and use a discreteevent simulation to analyse the effects on workloads and capacity utilization of a given fleet of police cars. The simulation model predicts the spatial and temporal occurrence of police operations and dispatches available vehicles from different districts, in order to model resource sharing in emergency response. This provides key insights into the required capacity over time and constitutes a crucial first step for an adequate capacity planning.
Operational planning at transshipment nodes is a wide and challenging field of research that covers a vast number of distinct relevant applications, spanning from seaport container terminals to rail terminals to cross-docks. In this work, we study the feasibility version of a fundamental synchronization problem that assigns incoming vehicles to docking resources subject to handover relations. We carry out a comprehensive analysis of computational complexity of various problem variants and establish structural connections to famous decision problems in graph theory. We further propose an exact solution algorithm for finding feasible dock assignments, if vehicles can visit the node only once and evaluate its performance in a comprehensive computational study.
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