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大学院理工学研究科 システムデザイン工学専攻 土木環境工学コース |
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2017年04月-2022年03月
東北大学 大学院工学研究科 土木工学専攻 卒業
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2015年04月-2017年03月
東北大学 工学部 建築・社会環境工学科 卒業
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2024年04月-継続中
秋田大学 大学院理工学研究科 助教
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2022年04月-2024年03月
八千代エンジニヤリング（株） 技術創発研究所 研究員
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Group-theoretic Bifurcation Mechanisms for Economic Agglomerations on a Square Lattice
Yosuke Kogure
2022年03月
単著
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Satellite City Formation for a Spatial Economic Model: Bifurcation Mechanism in a Hexagonal Domain
Hiroki Aizawa, Kiyohiro Ikeda, Yosuke Kogure
Networks and Spatial Economics 23 ( 3 ) 529 - 558 2023年09月 [査読有り]
研究論文（学術雑誌）
The economic agglomeration of one large city surrounded by satellite cities is observed worldwide and is a topic of keen economic interest. We theoretically investigate where such satellite cities emerge in a two-dimensional economic space in which discrete locations are evenly distributed in a regular-hexagonal domain. To elucidate this emergence, we introduce two viewpoints: (1) the bifurcation mechanism of the full agglomeration at the geographical center in this domain (mono-center), which produces satellite cities around this center, and (2) the existence of invariant patterns, which are equilibria for any value of the transport cost parameter. Theoretically-predicted agglomeration patterns are ensured to exist as stable equilibria for a spatial economic model proposed by Forslid and Ottaviano (2003). We theoretically find one large central city surrounded by hexagonal satellite cities that is a two-dimensional counterpart of the core-periphery pattern (Krugman 1991). Moreover, we demonstrate that spatial patterns of twin cities, three cities, and racetrack cities are absorbed into the mono-center as the transport cost decreases. These transitions are ubiquitously observed in the two-dimensional spatial platform with the geographical center.
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Global-Local Spatial Platform for Economic Geography: Mechanism for Sustaining Bifurcation
Y. Kogure, K. Ikeda
International Journal of Bifurcation and Chaos 32 ( 11 ) 2022年09月 [査読有り]
研究論文（学術雑誌）
This paper develops a spatial platform for economic agglomerations that can represent a hierarchical structure of cities, towns, and so on. A global system models geographical distribution of a system of cities, while population size and local geography of each city are modeled by an individual square lattice network. The mechanism of economic agglomeration is described by economic geography models with the replicator dynamics. As a major theoretical contribution of this paper, we elucidate the bifurcation mechanism of the mono-centric distribution in a square domain. Such bifurcation expresses how satellite places appear around a large city. This bifurcation behavior, called sustaining bifurcation, is different from symmetry-breaking bifurcation studied in nonlinear mathematics, and is not given much attention in economic geography, despite its importance. An air-network of cities with the seven largest hub airports in USA is employed as a realistic example, and is modeled as a global-local system comprising a series of local square lattices with different sizes connected by an equidistant economy. This system for an economic geography model displays successive sustaining bifurcations occurring many times leading to gradual emergence of satellite places around a large city.
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Group-Theoretic Bifurcation Mechanism of Economic Agglomerations on a Square Lattice
Y. Kogure, K. Ikeda, H. Aizawa
International Journal of Bifurcation and Chaos 31 ( 13 ) 2021年10月 [査読有り]
研究論文（学術雑誌）
We elucidate the mechanism of the self-organization of square agglomeration patterns that are described by spatial economic models on a square lattice with periodic boundary conditions. Focusing on the symmetry of the square lattice, we conduct a group-theoretic analysis and obtain bifurcating patterns from the uniform distribution. Furthermore, for the replicator dynamics, which are widely used in economics, we pay attention to the existence of invariant patterns that are solutions to the governing equation for any value of the bifurcation parameter (the trade freeness for spatial economic models). We advance invariant patterns on the square lattice as candidates of stable equilibria. Using a prototype spatial economic model proposed by Forslid and Ottaviano [2003], we numerically show a tendency that bifurcating solutions arrive at invariant patterns after bifurcation. This tendency is advanced as the underlying mechanism of the progress of economic agglomerations that is to be considered in the study of spatial economic agglomerations.
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相澤 大輝, 池田 清宏, 木暮 洋介, 大澤 実, José Maria GASPAR
土木学会論文集D3（土木計画学） ( 公益社団法人 土木学会 ) 76 ( 4 ) 282 - 298 2020年 [査読有り]
研究論文（学術雑誌）
都市への人口集積現象のメカニズムは新経済地理学モデルの理論分析を通じて研究されており，分岐を通じて集積パターンが形成されることが解明されている．しかし，多くの研究は2立地点空間や競技場経済のような対称性の高い空間を仮定しており，現実空間がもつ地理的優位性を捨象している．本研究では，境界がある線分上に等間隔に都市が分布する線分都市経済に着目し，単一の巨大都市型の集積が，衛星都市を含む都市群の集積に変化するメカニズムを，分岐解析により明らかにする．また，解析例としてForslid & Ottaviano<sup>1)</sup>のモデルをとりあげる．その結果，工業財への支出割合が大きいほど，あるいは，財の代替弾力性が小さくなるほど，衛星都市が中心都市から離れた箇所で発現することが明らかになった．
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Invariant patterns for replicator dynamics on a hexagonal lattice
K. Ikeda, Y. Kogure, H. Aizawa, Y. Takayama
International Journal of Bifurcation and Chaos 29 ( 6 ) 2019年06月 [査読有り]
研究論文（学術雑誌）
A hexagonal lattice is a promising and plausible spatial platform for economic agglomeration in spatial economic models. This paper aims at the elucidation of agglomeration mechanisms for the replicator dynamics on this lattice. Attention is paid to the existence of invariant solutions that retain their spatial patterns when the bifurcation parameter changes. Such existence is a special feature of the replicator dynamics, which is widely used in economics. A theoretical procedure to find invariant patterns is proposed and possible invariant patterns are advanced and classified. Among a plethora of theoretically possible invariant patterns, those which actually become stable for a spatial economic model are investigated numerically. The major finding of this paper, is the demonstration of equilibrium curves of invariant patterns that are connected by those of noninvariant ones to form a complicated mesh-like structure, just like the threads of warp and weft. It would be an important scientific mission to elucidate the mechanism of this complicated structure, and contribute to the study in economic geography.