Offline map matching identifies corresponding roads to a GPS trajectory represented by a series of recorded geographic coordinates (GPS points) to the road network. This paper defines matching error as cost on the corresponding road-link to matched GPS points and formulates the offline map matching problem as a shortest path problem with resource constraints. By regarding matched points on one link as a type of resource consumed, the resource constraint indicates that the number of matched GPS points equals the total number of points in the given trajectory. We propose an offline map matching algorithm based on shortest paths by calculating the matching error on each link and extending the classic label-setting shortest path algorithm to find the path with the minimum total matching error for all GPS points. We use real-world taxi trajectories to compare our algorithm with three state-of-the-art map matching algorithms. Our algorithm outperforms all benchmark algorithms in terms of both matching accuracy and computational efficiency. Our algorithm achieves greater matched length (5.36 to 12.27% larger) and lower mis-matched length (3.72 to 75.30% smaller) at a very high matching speed (60.59 points per second on average over thirteen sampling intervals).

We study how to model and handle correlated travel times in two-stage stochastic vehicle-routing problems. We allow these travel times to be correlated in time and space; that is, the travel time on one link in one period can be correlated to travel times on the same link in the next and previous periods as well as travel times on neighboring links (links sharing a node) in both the same and the following periods. Hence, we are handling a very high-dimensional dependent random vector. We discuss how such vehicle-routing problems should be modeled in time and space, how the random vector can be represented, and how scenarios (discretizations) can meaningfully be generated to be used in a stochastic program. We assume that the stochastic vehicle-routing problem is being solved by a search heuristic and focus on the objective function evaluation for any given solution. Numerical procedures are given and tested. As an example, our largest case has 142 nodes, 418 road links, and 60 time periods, leading to 25,080 dependent random variables. To achieve an objective function evaluation stability of 1%, we need only 15 scenarios for problem instances with 64 customer nodes and nine vehicles.

This paper addresses a supply chain scheduling problem with consideration of production and transportation operations. This problem is formulated as a bilevel mixed integer nonlinear program. An evolution-strategy-based bilevel optimization model is developed to handle this problem. The performance of the proposed model is evaluated by numerical experiments based on real-world data and industrial-size problems. Experimental results show that the proposed model can solve the investigated problem effectively.

This research investigated a retail sales forecasting problem based on early sales. An effective multivariate intelligent decision-making (MID) model is developed to handle this problem by integrating a data preparation and preprocessing module, a harmony search-wrapper-based variable selection (HWVS) module and a multivariate intelligent forecaster (MIF) module. The HWVS module selects out the optimal input variable subset from given candidate inputs as the inputs of MIF. The MIF is proposed to model the relationship between the selected input variables and the sales volumes of retail products, and then employed to forecast the sales volumes of retail products. Experiments were conducted to evaluate the effectiveness of the proposed model. Results show that it is statistically significant that the proposed MID model can provide superior forecasts to ELM-based model and generalized linear model.

This paper investigates a flexible assembly line balancing (FALB) problem with work sharing and workstation revisiting. The mathematical model of the problem is presented, and its objective is to meet the desired cycle time of each order and minimize the total idle time of the assembly line. An optimization model is developed to tackle the addressed problem, which involves two parts. A bilevel genetic algorithm with multiparent crossover is proposed to determine the operation assignment to workstations and the task proportion of each shared operation being processed on different workstations. A heuristic operation routing rule is then presented to route the shared operation of each product to an appropriate workstation when it should be processed. Experiments based on industrial data are conducted to validate the proposed optimization model. The experimental results demonstrate the effectiveness of the proposed model to solve the FALB problem.