The Vehicle Routing Problem with Time Windows is an important task in logistic planning. The expenditure on employing labor force, i.e., drivers for vehicles, accounts for most of the costs in this domain. We propose an initialized Ant Colony approach, IACO-VRPTW, with the primary goal (f1) to reduce the number of vehicle needed to serve the customers and the second-priority goal (f2) of decrea...

This vignette describes gdistance, an R package which provides functionality to calculate various distance measures and routes in heterogeneous geographic spaces represented as grids. Distances are fundamental to geospatial analysis (Tobler 1970). The most commonly used geographic distance measure is the great-circle distance, which represents the shortest line between two points, taking into a...

We investigate how visual motion registered during one’s own movement through a structured world can be used to gauge travel distance. Estimating absolute travel distance from the visual flow induced in the optic array of a moving observer is problematic because optic flow speeds co-vary with the dimensions of the environment and are thus subject to an environment specific scale factor. Discrim...

The terms ‘medical tourism’ and ‘health tourism’ cover many phenomena. Individuals able to afford the costs have frequently traveled great distances to consult with healers considered especially competent in their field. A reputation for expertise has, for the past century, been linked to technological capacity and those who can do so may prefer to travel to places such as the Mayo Clinic rathe...

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the "zone of disturbance" for Kittlitz's and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the l...

Dick Voith is a senior vice president and principal at Econsult Corporation, Philadelphia. When he wrote this article, he was an economic advisor in the Research Department of the Philadelphia Fed. The dominant trend in metropolitan development in the 20th century was the increasing use of land per capita. As households moved to the suburbs, both houses and residential lots increased dramatical...

Group-living animals face intragroup scramble and intergroup contest competitions. Many studies have shown that larger groups bear the costs of intragroup scramble competition, which negatively affects the reproductive success of females. Unlike most primate species, Japanese macaques in the Yakushima coastal forest show increased reproductive success with group size. However, it remains unclea...

Environmental effects on walking behavior have received attention in recent years because of the potential for policy interventions to increase population levels of walking. Most epidemiologic studies describe associations of walking behavior with environmental features. These analyses ignore the dynamic processes that shape walking behaviors. A spatial agent-based model (ABM) was developed to ...

Most of the studies on vehicle routing problem with time windows (VRPTW) aim to minimize total travel distance or travel time. This paper presents the VRPTW with a new objective function of minimizing the total fuel consumption. A mathematical model is proposed to formulate this problem. Then, a novel tabu search algorithm with a random variable neighborhood descent procedure (RVND) is given, w...