Atsushi Takizawa

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Given a directed graph <i>D = (V, A)</i> and a set of specified vertices S = {s<sub>1</sub>,&#8230;,s<sub>d</sub>} &#8838; <i>V</i> with |S| = <i>d</i> and a function <i>f</i>: S &#8594; N where N denotes the set of natural numbers, we present a necessary and sufficient condition that there exist &#931;s<sub>i</sub> &#949; arc-disjoint in-trees denoted by(More)
In evacuation situations, it is very important that we have enough refuges. Therefore, we have to check in advance if capacities of refuges in urban areas are sufficiently large. In this paper, we present an algorithm for this problem by using a dynamic network flow which is a branch of the network flow theory, and then we apply our method to a numerical(More)
abstract In December 2004, the Sumatra-Andaman earthquake occurred. It triggered tsunamis, and tragedy fell upon many people. Not only earthquakes but also diverse disasters occurred and caused serious damages in many countries. Therefore it is very important to establish crisis management systems against large-scale disasters such as big earthquakes,(More)
In recent years, catastrophic disasters by massive earthquakes are increasing in the world, and disaster management is required more than ever. In the case of disasters such as tsunami from which the slight delay of evacuation deprives of life. In this article, we formalize the emergency evacuation planning model for the evacuation from tsunami etc. based(More)
An optimization system based on genetic algorithms (GAs)-simulating an evolutionary feedback for the design of theatres-was developed. The first GA model was an optimization of the walls and the ceiling of a hall of the wide-shoebox type. The second model was an optimization of reflectors for a fan shaped outdoor theatre. The final results show that the(More)