Keiji Maekawa

A genetic solution for the traveling salesman problem by means of a thermodynamical selection rule

For successful applications of the genetic algorithm, there are two important points to be considered. The first point is the design of the fitness landscape introduced by the representation of the solution as a gene and searching operations such as crossover and mutation. The second is control of the convergence brought about by the selection operation. In the conventional implementation of GA, these two points are mutually dependent, i.e., a suitable selection pressure varies largely depending on, e.g., the crossover operator. Hence, it requires much trial-and-error effort to find a nice configuration of GA. The authors apply a novel selection rule, the Thermodynamical Genetic Algorithm (TDGA) proposed by N. Mori et al. (1995) to the traveling salesman problem (TSP), and propose an adaptive annealing schedule of the temperature in TDGA. Computer simulation with several crossover operators for TSP shows that TDGA reduces the mutual dependency between the fitness landscape and the convergence process.

A comparison study of genetic codings for the traveling salesman problem

In applying the genetic algorithm (GA) to optimization problems, both a genetic coding method and a method of genetic operations are essential for making a search effective. Moreover, freedom in a genetic representation, e.g. redundant coding, is indispensable for achieving a successful self-organization in GA. This paper treats the case of the application of a GA to the traveling salesman problem (TSP), and proposes four ways of redundantly coding a tour plan. Then, based on several computational experiments, the coding methods have been mutually compared from the viewpoints of the search efficiency, i.e. the effects of genetic operators, the quality of the obtained tours, and the number of generations required for finding near-optimal tours. As a result, the search for the optimal tour is found to be most effective in the case of the coding based on the link information, while the simple GA is found not to be sufficient for solving large-scale problems. Then, the GA is modified by supplementing some new mechanisms. The results of the computational experiments suggest the applicability of the modified GA to large-scale problems.<<ETX>>

An Enhanced Location Privacy Framework with Mobility Using Host Identity Protocol

Location privacy is one of the problems involved in IP mobility. There are two proposed frameworks for this problem based on Host Identity Protocol (HIP); HIP Location Privacy Framework provides partial location privacy with mobility, while BLIND provides complete location privacy without mobility. In this paper, we integrate their strong points, i.e. complete location privacy with mobility. Our framework gives a way to decouple identifiers for mobility from identifiers for end-to-end communications. We construct an extensional mobility management protocol of BLIND, and discuss a trade-off in terms of efficiency and operational cost.

AT ACS: First Phase Control System And ItsExperimental Test Results

The test run of AT ACS (Advanced Train Administration And Communications System)** which is managed by East Japan Railway Company was carried out. AT ACS is a radio communication-based train control system. Hitachi, Ltd. developed three field controller sets (a set constructed form a main controller and a sub-controller), two management servers and two sets of a on-board controller for two test trains. Outputs from main and sub-field controllers are mixed and transmitted to vehicles, and these data are verified by the on-board controller. Virtual trains generated in field controllers were also used in field test runs. Open & close control and handover control of communication channels were performed in the field controllers. A hazard state never happened in these test runs. Transactions on the Built Environment vol 34,