Dense Monolayers of Monodisperse Opaque Spheres: Transmission and diffraction in the fraunhofer domain

The transmission and diffraction of radiation through dense monolayers of monodisperse opaque spheres were studied for the Fraunhofer domain. Theoretical considerations, numerical calculations and experiments on ultrasonic transmission and on laser light transmission and diffraction yielded corresponding results. Complementary studies included the cases of sterically non-interacting particles (by numerical simulation) and of small particle size parameters (by ultrasonic extinction). Transmission was found to be, in general, a non-linear function of the monolayer density. Secondary effects on the transmission can be attributed to the effect of the monolayer structure (characterized by the pair correlation function) on the angular distribution of diffracted intensity. The results were found to be in accordance with experimental results on extinction in three-dimensional systems.     

Improved modeling and solution methods for the multi-resource routing problem

This paper presents modeling and solution method improvements for the Multi-Resource Routing Problem (MRRP) with flexible tasks. The MRRP with flexible tasks is used to model routing and scheduling problems for intermodal drayage operations in which two resources (tractors and trailers) perform tasks to transport loaded and empty equipment. Tasks may be either well defined, in which both the origin and the destination of a movement are given, or flexible, in which the origin or the destination is chosen by the model. This paper proposes methods to effectively manage the number of options considered for flexible tasks (either feasible origins for a known destination or feasible destinations for a known origin). This modeling change generates sufficient options to allow for low-cost solutions while maintaining reasonable computational effort. We also propose a new solution method that uses randomized route generation. Computational results from test cases show that these changes improve the quality of solutions by at least 5% in the test cases as compared to methods from previous studies.