著者
宮武 勇登
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.28, no.3, pp.15-22, 2018-09-26 (Released:2018-12-26)
参考文献数
35

Continuous stage Runge-Kutta (CSRK) methods, which were introduced around 2010, are a framework of iterative numerical methods for solving ordinary differential equations. It turned out that some CSRK methods preserve some underlying geometric structures of differential equations, such as symplecticity or energy-preservation of Hamiltonian systems. This paper reviews CSRK methods and their recent developments with emphasis on their structure-preservation properties.
著者
川越 大輔
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.30, no.4, pp.16-23, 2020-12-22 (Released:2021-03-31)
参考文献数
18

Optical tomography is a new medical imaging technique which makes use of near infrared light, and it is mathematically modeled as an inverse problem to determine a coefficient in the stationary transport equation from boundary measurements. In this paper, we show two results on regularity of solutions to the direct problem of the stationary transport equation. The first result is to describe discontinuity of the solution which arises from discontinuous points of the incoming boundary data, and we show the exponential decay of a jump of the solution on a discontinuous point. The decay gives an idea for solving the inverse problem. The second one is to give a W1, p estimate of the solution to the direct problem in two-dimensional cases. Here, the exponent p has an upper bound pm, which is a real number depending only on the shape of the domain. This estimate is crucial when we solve the direct problem numerically with the discrete-ordinate discon-tinuous Galerkin method.
著者
今 隆助
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.25, no.3, pp.112-119, 2015-09-25 (Released:2017-04-08)

Periodical cicadas are known for their perfectly synchronized prime number emergences of either 13 or 17 year period. One of th eexplanations for the prime periodicity is that the prime periods are selected to prevent cicadas from resonating with predators with submultiple periods. This paper considers this hypothesis by investigating a population model for periodical predator and prey. The study shows that if the periods of the two periodical species are not coprime, then the predator cannot resist the invasion of the prey. On the other hand, if the periods are coprime, then the predator can eradicate the prey. These results suggest that prime number periods are disadvantageous under periodic predation pressure. Numerical investigations illustrate a non-coprime case where both populations coexist.
著者
桂 利行
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.14, no.1, pp.71-74, 2004-03-25 (Released:2017-04-08)
参考文献数
3
著者
松葉 育雄
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.5, no.3, pp.192-208, 1995-09-18 (Released:2017-04-08)
参考文献数
22
被引用文献数
1

不規則に変動する成分をランダムノイズとする統計的手法に従う時系列データ処理法に対し,カオスの発見以来,確率的成分を有しない非線形ダイナミクスが内在するメカニズムのみから不規則な様相を見せることが明らかにされ,不規則データのモデル化に関して従来と異なるアプローチが要求されるようになってきた.実際,カオティックな時系列データに対して統計モデルよりも非線形なモデルを基礎にした決定論的な方式が優れていることが示されるようになってきた.本稿では,カオスモデルだけではなく実際的な例を通してニューラルネットワークを予測の道具に用いた非線形予測の可能性を議論する.
著者
國廣 昇 太田 和夫
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.18, no.1, pp.23-29, 2008-03-25 (Released:2017-04-08)
参考文献数
17
被引用文献数
1
著者
岩崎 義光
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.5, no.3, pp.209-229, 1995-09-18 (Released:2017-04-08)
参考文献数
22

The theory of grain boundary structure is reviewed from the mathematical point of view. High-order twins are mathematically introduced and developed up to the 4th order twins in the case of cubic crystals. The coincidence-site lattice, 0-lattice and DSC lattice are considered with emphasis on their algebraic aspects. Some applications of high-order twins and coincidence-site boundaries are discussed to point out these importance in the field of material sciences and industries.
著者
横山 直人 高岡 正憲
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.26, no.4, pp.15-23, 2016-12-22 (Released:2017-03-25)
参考文献数
29

Elastic-wave turbulence has been used for a testbed for the weak turbulence theory, since it can be examined by numerical and laboratory experiments. The elastic-wave turbulence has distinctive characteristics as a wave turbulence system, one of which is the coexistence of the weak and strong turbulence. Recent researches on the elastic-wave turbulence are reviewed, not restricted to the weak turbulence properties, with focusing on energy transfers under large-scale external forcing.
著者
今井 桂子
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.6, no.1, pp.29-39, 1996-03-15 (Released:2017-04-08)
参考文献数
14

Triangulations have been one of main topics in computational geometry and other fields in recent years. In the planar case, any pair of triangulation can be transformed to each other by a sequence of so-called Delaunay flips, and enumeration of all triangulations can be done by reverse search. However, there is no known result for higher-dimensional triangulations. Recently, some types of triangulations have been found to bridge geometric issues and algebraic ones. Regular triangulations are of such a type, and form a meaningful wide subclass of triangulations of points in general dimensions. Especially, regular triangulations have a close connection with discriminants of polynomials in several variables. Restricting ourselves to the class of regular triangulations in any dimensions, we know that such triangulations correspond to vertices of some polytope, and we can enumerate all regular triangulations by reverse search.
著者
吉村 健司 高橋 一弘
出版者
一般社団法人 日本応用数理学会
雑誌
応用数理 (ISSN:24321982)
巻号頁・発行日
vol.7, no.1, pp.2-23, 1997-03-17 (Released:2017-04-08)
参考文献数
12

An electric power system is a large-scale energy system composed of a lot of equipment such as power generating units, transmission lines, voltage transformers and power demand loads. It is also a very complex system including generator's electromagnetic dynamics and many control system's characteristics to maintain a constant level of voltage and systemfrequency. Eigenvalue analysis is one of the methods to handle a power system stability problem associated with the system dynamic perfomance. This paper describes mathematical models of power system components and also explains a calculation technique of eigenvalue analysis to evaluate a large -scale power system stability. Its application for improving stability enhancement using eigenvalue sensitivity is also described in this paper.