The classical shortest route problem in networks assumes deterministic link weights, and route evaluation by a utility (or cost) function that is linear over path weights. When the environment is stochastic and the “traveler’s” utility function for travel attributes is nonlinear, we define “optimal paths” that maximize the expected utility. In this setting, the concept of temporary and permanent preferences for route choices is introduced. It is shown that when the utility function is linear or exponential (constant risk averseness), permanent preferences prevail and an efficient Dijkstra-type algorithm can be used.
Headway control strategies have been proposed as methods for correcting transit service irregularities and thereby reducing passenger wait times at stops. This paper addresses a particular strategy which can be implemented on high frequency routes (headways under Is12 minutes), in which buses are held at a control stop to a threshold headway. An algorithm is developed which yields the optimal control stop location and optimal threshold headway with respect to a system wait function. The specification of the wait function is based on the development of several empirical models, including a headway variation model and an average delay time model at control stops.A conclusion is reached that the headway variation does not increase linearly along a route, a common assumption made in many previous studies. Furthermore, the location of the optimal control stop and threshold value are sensitive to the passenger boarding profile, as expected. The algorithm itself appears to have practical application to conventional transit operations.
The Military Occupational Specialty Level System (MOSLS) of the US Army's enlisted force manpower decision support system (DSS) was developed to support programming and planning decisions in the areas of recruitment, training and education, promotion, reclassification and reenlistment, and separation and retirement. The DSS contains a combined linear optimization-simulation personnel flow model. The flow simulation is used as a controlling mechanism to stabilize the optimizer's results and to reflect in greater detail those facets of personnel management that cannot be modeled within a linear programming framework either because of problem size limitations or accuracy considerations. The models can be exercised in a what-if mode where policy can be modified and the predicted effects evaluated. The system is supported by a state-of-the-art, on-line data base and various support software permitting statistical analysis, report generation, and direct data base query.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.