Ⅰ
Commodity Flow
”The sustainability and the survivability of Kyoto’s traditional craft industry revealed from supplier-customer network”
Daisuke Sato, Yuichi Ikeda, Shuichi Kawai, Maximilian Schich
PLOS ONE, 15, 11, e0240618-e0240618, 2020/11
Due to the changes in consumer demand and generational transformations, Kyoto’s traditional craft industry has suffered substantial revenue losses in recent years. This research aimed to characterize Kyoto’s traditional craft industry by analyzing the supplier-customer network involving individual firms within the Kyoto region. In the process, we clarify the community structure, key firms, network topological characteristics, bow-tie structure, robustness, the vulnerability of the supplier-customer network as crucial factors for sustainable growth. The community and bow-tie structure analysis became clear that the traditional craft industry continues to occupy an important position in Kyoto’s industrial network. Furthermore, we clarify the relationship between modern and traditional craft industries’ network characteristics and their relative profitability and productivity. It became evident that the traditional craft industry has a different network structure from the modern consumer games and electric machinery industries. The modern industries have the strongly coupled component, and the attendant firms there create high value-added and play a significant role in driving the entire industry, while more traditional craft industries, such as the Nishijin silk fabrics and Kyoto doll industries, do not have this strongly coupled component. Moreover, the traditional crafts industry does not have a central firm or a dense network for integrating information, which is presumed to be a factor in the decline of the traditional craft industry.
”Testing“efficient supply chain propositions” using topological characterization of the global supply chain network”
Abhijit Chakraborty, Yuichi Ikeda
PLOS ONE, 15, 10, e0239669-e0239669, 2020/10
In this paper, we study the topological properties of the global supply chain network in terms of its degree distribution, clustering coefficient, degree-degree correlation, bow-tie structure, and community structure to test the efficient supply chain propositions proposed by E. J.S. Hearnshaw et al. The global supply chain data in the year 2017 are constructed by collecting various company data from the web site of Standard & Poor’s Capital IQ platform. The in- and out-degree distributions are characterized by a power law of the form of γin = 2.42 and γout = 2.11. The clustering coefficient decays with an exponent βk = 0.46. The nodal degree-degree correlations 〈knn(k)〉 indicates the absence of assortativity. The bow-tie structure of giant weakly connected component (GWCC) reveals that the OUT component is the largest and consists 41.1% of all firms. The giant strong connected component (GSCC) is comprised of 16.4% of all firms. We observe that upstream or downstream firms are located a few steps away from the GSCC. Furthermore, we uncover the community structures of the network and characterize them according to their location and industry classification. We observe that the largest community consists of the consumer discretionary sector based mainly in the United States (US). These firms belong to the OUT component in the bow-tie structure of the global supply chain network. Finally, we confirm the validity of Hearnshaw et al.’s efficient supply chain propositions, namely Proposition S1 (short path length), Proposition S2 (power-law degree distribution), Proposition S3 (high clustering coefficient), Proposition S4 (“fit-gets-richer” growth mechanism), Proposition S5 (truncation of power-law degree distribution), and Proposition S7 (community structure with overlapping boundaries) regarding the global supply chain network. While the original propositions S1 just mentioned a short path length, we found the short path from the GSCC to IN and OUT by analyzing the bow-tie structure. Therefore, the short path length in the bow-tie structure is a conceptual addition to the original propositions of Hearnshaw.
”Multilayer network analysis of the drugs development cycle in the global pharmaceutical industry”
Hiromitsu Goto, Mari Jibu, Wataru Souma, Yuichi Ikeda
Applied Network Science ,5 , 1, 2020/12
Drug development is a time-consuming process from the start of research to obtaining approval, and the probability of success with a candidate compound is extremely low. We aim to understand the characteristics of the flow and localization of knowledge during drug development in the global pharmaceutical industry. We analyze the multilayer network constructed with the drug pipeline layer, global supply chain layer, and global ownership layer. First, we identify the bow-tie structure and the community structure of each network layer. The obtained bow-tie structure shows the large strongly connected component and suggests that the knowledge flow in drug pipelines has similar characteristics as the supply chain network. The communities in each layer are characterized by country, category of the company, and bow tie component. We then study the multilayer network’s knowledge flow, conduct a statistical test, and verify the significance of the overlapping links between the drug pipeline and supply chain layers. Our results suggest a strong connection between open innovation in the pharmaceutical industry and firms’ economic activities in the supply chain.
”Trade network reconstruction and simulation with changes in trade policy"
Y. Ikeda, H. Iyetomi
Evolutionary and Institutional Economics Review, 15, 2, 495-513, 2018/12
The interdependent nature of the global economy has become stronger with increases in international trade and investment. We propose a new model to reconstruct the international trade network and associated cost network by maximizing entropy based on local information about inward and outward trade. We show that the trade network can be successfully reconstructed using the proposed model. In addition to this reconstruction, we simulated structural changes in the international trade network caused by changing trade tariffs in the context of the government’s trade policy. The simulation for the FOOD category shows that import of FOOD from the US to Japan increase drastically by halving the import cost. Meanwhile, the simulation for the MACHINERY category shows that exports from Japan to the US decrease drastically by doubling the export cost, while exports to the EU increased.
”Who buys what, where: Reconstruction of the international trade flows by commodity and industry"
Y. Ikeda
Complex Networks & Their Applications V (Studies in Computational Intelligence Volume 693), 2016/12
We developed a model to reconstruct the international trade network by considering both commodities and industry sectors in order to study the effects of reduced trade costs. First, we estimated trade costs to reproduce WIOD and NBERUN data. Using these costs, we estimated the trade costs of sector specific trade by types of commodities. We successfully reconstructed sector-specific trade for each types of commodities by maximizing the configuration entropy with the estimated costs. In WIOD, trade is actively conducted between the same industry sectors. On the other hand, in NBER-UN, trade is actively conducted between neighboring countries. This seems like a contradiction. We conducted community analysis for the reconstructed sector-specific trade network by type of commodities. The community analysis showed that products are actively traded among same industry sectors in neighboring countries. Therefore the observed features of the community structure for WIOD and NBER-UN are complementary.
”Community Dynamics and Controllability of G7 Global Production Network"
Y. Ikeda
11th International Conference on Signal-Image Technology & Internet-Based Systems (SITIS), 391-397, 2015/11
We study G7 Global Production Network constructed using production index time series from January 1998 to January 2015 for G7 countries. Collective motion of G7 Global Production Network is analyzed using complex Hilbert principal component analysis, community analysis for single layer network and multiplex networks, and structural controllability. Through tout this analysis we characterize features of collective motion for G7 Global Production Network during economic crisis in 2008.
”Community Structure and Dynamics of the Industry Sector-Specific International-Trade-Network”
Y. Ikeda, H. Iyetomi, T. Mizuno, T. Ohnishi, T. Watanabe
10TH INTERNATIONAL CONFERENCE ON SIGNAL-IMAGE TECHNOLOGY AND INTERNET-BASED SYSTEMS SITIS 2014, 456-461, 2014
We analyzed the industry sector-specific international trade data from 1995 to 2011 to clarify the structure and dynamics of communities that consist of industry sectors in various countries linked by international trade. We applied conventional community analysis to each time slice of the international trade network, and then identified the links between communities in adjoining years by using the World Input-Output Database. This database contains the industry sector specific international trade data on 41 countries and 35 industry sectors. The identified link structure shows that a triple backbone structure exists in the international trade network. We used the Hilbert transform to evaluate the phase time series of the growth rate of value added for 1435 nodes and then estimated the complex order parameters for communities. The respective amplitude for the order parameter of each community was observed to be greater than the amplitude for all sectors. This means active trade produces higher phase coherence within each community. Phase coherence decreased gradually in the late 1990's but increased sharply in 2001 and 2002.
”Correlated performance of firms in a transaction network”
Y. Ikeda, H. Aoyama, H. Iyetomi, Y. Fujiwara, W. Souma
Journal of Economic Interaction and Coordination, 3, 1, 73-80, 2008/06
The correlation of firms’ performance on a transaction network is studied by analyzing financial and transaction data. Statistically significant correlation coefficients are obtained as evidence for the firm interactions. The firm interactions are taken into account in the basic equation of firm activity. Forty percent of residuals are explained by considering the firm interactions. The overall structure of the transaction network, i.e., the connectivity of industry sectors, is analyzed.