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)
The global methane (CH 4) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH 4 over the past decade. Emissions and(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)
Using spatial data mining techniques, we analyze car-related crimes such as auto theft, auto parts theft, and breaking into a car in the area of Nishikyo-ku, Kyoto City. The strategy of natural surveillance proposed by Crime Prevention Through Environmental Design (CPTED) is taken into consideration as visibility attributes. From the viewpoint of risk(More)