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Naoya Fujiwara

Section

Graduate School of Information Sciences

Job title

Associate Professor

Degree

博士（情報学）（京都大学）
修士（情報学）（京都大学）

researchmap

https://researchmap.jp/naoyafujiwara

J-GLOBAL ID

201801019454177690

Research History 11

2023/10 - Present

The University of Tokyo
2021/10 - Present

Japan Science and Technology Agency　PRESTO researcher
2020/04 - Present

The University of Tokyo　Center for Spatial Information Science at the University of Tokyo　Visiting Researcher
2019/10 - Present

The University of Tokyo　Institute of Industrial Science
2018/04 - Present

Tohoku University　Graduate School of Information Sciences　Associate Professor
2017/05 - 2018/03

The University of Tokyo　Institute for Industrial Science　Project Lecturer
2014/04 - 2017/05

The University of Tokyo　Center for Spatial Information Science　Assistant Professor
2012/02 - 2014/03

FIRST, Aihara Innovative Mathematical Modelling Project　Researcher
2010/04 - 2012/01

Potsdam Institute for Climate Impact Research　Researcher
2008/06 - 2010/03

University of Potsdam　Researcher
2007/04 - 2008/03

Kyoto University　Graduate School of Informatics　Researcher

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Committee Memberships 3

電子情報通信学会複雑コミュニケーションサイエンス研究会　専門委員

2013 - Present
日本物理学会　領域１１運営委員

2019/04 - 2020/03
The 3rd ACM SIGSPATIAL International Workshop on Prediction of Human Mobility (PredictGIS 2019) Oragnizing committee member

2019/11 - 2019/11

Professional Memberships 4

応用地域学会
GEOGRAPHIC INFORMATION SYSTEMS ASSOCIATION OF JAPAN
THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS
THE PHYSICAL SOCIETY OF JAPAN

Research Interests 4

数理工学
空間情報科学
非線形動力学
複雑ネットワーク

Research Areas 2

Natural sciences / Mathematical physics and basic theory /
Informatics / Soft computing /

Awards 7

Honarable Mention of the Best Poster Award

2025/04　Eighth Northeast Regional Conference on Complex Systems　Epidemic Induced Network Evolution
石田實記念財団研究奨励賞

2022/12　一般財団法人石田實記念財団　人流データのネットワーク分析およびその応用に関する研究
2022年度日本神経回路学会論文賞

2022/07　日本神経回路学会　Chaos may enhance expressivity in cerebellar granular layer
CSIS DAYS 2021 優秀共同研究発表賞

2021/11　東京大学空間情報科学研究センター
優秀賞

2019/11　第17回情報学ワークショップ　Word Embeddingsを用いた斬新さと手堅さを兼ね備えた経済学における研究テーマの自動生成
Poster Competition 2nd Prize

2019/07　Netmob2019　Understanding Post-Disaster Population Recovery Patterns
CSIS DAYS 2016 優秀研究発表賞

2016/11　東京大学空間情報科学研究センター

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Papers 52

The size distribution of ‘cities’ delineated with a network theory‐based method and mobile phone GPS data Peer-reviewed

Shota Fujishima, Naoya Fujiwara, Yuki Akiyama, Ryosuke Shibasaki, Ritsu Sakuramachi

International Journal of Economic Theory　16　(1)　38-50　2020/03
Publisher: Wiley
DOI： 10.1111/ijet.12254 　

ISSN： 1742-7355

eISSN： 1742-7363
Understanding Post-Disaster Population Recovery Patterns Peer-reviewed

Takahiro Yabe, Kota Tsubouchi, Naoya Fujiwara, Yoshihide Sekimoto, Satish V. Ukkusuri

Journal of the Royal Society Interface　17　20190532　2020/02/19

DOI： 10.1098/rsif.2019.0532 　
Synchronization of mobile chaotic oscillator networks Peer-reviewed

Naoya Fujiwara, Jurgen Kurths, Albert Diaz-Guilera

CHAOS　26　(9)　2016/09

DOI： 10.1063/1.4962129 　

ISSN： 1054-1500

eISSN： 1089-7682
Synchronization in networks of mobile oscillators Peer-reviewed

Naoya Fujiwara, Juergen Kurths, Albert Diaz-Guilera

PHYSICAL REVIEW E　83　(2)　2011/02

DOI： 10.1103/PhysRevE.83.025101 　

ISSN： 1539-3755
Spectral universality of phase synchronization in non-identical oscillator networks Peer-reviewed

N. Fujiwara, J. Kurths

EUROPEAN PHYSICAL JOURNAL B　69　(1)　45-49　2009/05

DOI： 10.1140/epjb/e2009-00078-6 　

ISSN： 1434-6028

eISSN： 1434-6036
Pattern dynamics associated with dynamic phase transitions Peer-reviewed

Naoya Fujiwara, Takeo Kobayashi

PROGRESS OF THEORETICAL PHYSICS　119　(3)　361-379　2008/03

DOI： 10.1143/PTP.119.361 　

ISSN： 0033-068X
Dynamic phase transition in a rotating external field Peer-reviewed

Naoya Fujiwara, Takeo Kobayashi, Hirokazu Fujisaka

PHYSICAL REVIEW E　75　(2)　026202　2007/02

DOI： 10.1103/PhysRevE.75.026202 　

ISSN： 1539-3755
A review of human mobility: Linking data, models, and real-world applications Peer-reviewed

Yunhan Du, Takaaki Aoki, Naoya Fujiwara

Journal of Computational Social Science　8　(4)　90　2025/08/18
Publisher: Springer Science and Business Media LLC
DOI： 10.1007/s42001-025-00414-7 　

ISSN： 2432-2717

eISSN： 2432-2725

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Abstract Human mobility, encompassing activities ranging from daily commutes to long-term migration, plays a critical role in shaping societal structures, economic activities, and cultural exchanges. Its complex and multifaceted nature, driven by factors such as socioeconomic conditions, technological advancements, policy interventions, and environmental changes, has made human mobility a central focus of interdisciplinary research across various domains. This review explores recent advancements in human mobility studies, focusing on the integration of diverse data sources to analyze movement patterns. Key models of human mobility are introduced, addressing both individual-level dynamics, such as individual travel behavior, and population-level phenomena, such as migration flows. Furthermore, this review summarizes the practical applications of human mobility, particularly in urban planning and epidemic modeling, highlighting the significant implications of a comprehensive understanding of human mobility. Understanding these dynamics is essential for developing data-driven strategies to enhance urban infrastructure, manage public health risks, optimize transportation networks, and respond effectively to global mobility trends.
Geospatial analysis of toponyms in geotagged social media posts Peer-reviewed

Takayuki Hiraoka, Takashi Kirimura, Naoya Fujiwara

PLoS ONE　20　(6)　e0325022-e0325022　2025/06/05
Publisher: Public Library of Science (PLoS)
DOI： 10.1371/journal.pone.0325022 　

eISSN： 1932-6203
Geodemographic analysis of socioeconomic area disparities in tuberculosis incidence in Osaka City, Japan Peer-reviewed

Kaori Yamamoto, Shouhei Takeuchi, Tomoki Nakaya, Naoya Fujiwara, Junji Seto, Jun Komukai, Yuko Tsuda, Hideki Yoshida, Takayuki Wada

Scientific Reports　15　(1)　15968　2025/05/07
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-025-99711-4 　

eISSN： 2045-2322

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Abstract Regional disparities in the incidence of tuberculosis (TB) pose several challenges to effective TB control. This study aimed to investigate such disparities in Osaka City, Japan, by analyzing the relationship between TB incidence and residents’ socioeconomic indicators. Using 42 indicators from the 2010 population census, the city was clustered into 15 social areas through a factor analysis, and TB incidence during 2012–2016 was compared across the areas in 4,852 cases. Two geographically adjacent areas (Area D and O) exhibited significantly higher TB rates, each with distinct social characteristics. Area D consisted of a high proportion of young, single individuals working in the service sector as well as foreigners. Area O included a high proportion of day laborers, secondary industry workers, and individuals with lower educational levels. TB occurred more frequently in foreign-born patients aged < 60 years, and it was detected during treatment for other diseases in Area D compared with other areas. However, a high proportion of retreated patients aged 40–79 years, with a shorter delay in TB detection, was observed in Area O. The variations in this study provide insights into the relationship between socioeconomic indicators and regional disparities in TB incidence in local settings.
Mobility Patterns of Trailers Around International Container Terminals: A Case Study in Sendai Port, Japan Peer-reviewed

Huixuan Zheng, Chenbo Zhao, Yoshiki Ogawa, Ryuichi Shibasaki, Naoya Fujiwara

2024 IEEE International Conference on Big Data (BigData)　6823-6833　2025/01/16

DOI： 10.1109/BigData62323.2024.10825814 　
Directional intermodular coupling enriches functional complexity in biological neuronal networks International-journal Peer-reviewed

Nobuaki Monma, Hideaki Yamamoto, Naoya Fujiwara, Hakuba Murota, Satoshi Moriya, Ayumi Hirano-Iwata, Shigeo Sato

Neural Networks　184　106967-106967　2024/11/28
Publisher: Elsevier BV
DOI： 10.1016/j.neunet.2024.106967 　

ISSN： 0893-6080
Unveiling realistic mobility patterns with home–origin–destination data aggregation

Yunhan Du, Takaaki Aoki, Naoya Fujiwara

The European Physical Journal Plus　139　(5)　403　2024/05/10
Publisher: Springer Science and Business Media LLC
DOI： 10.1140/epjp/s13360-024-05142-x 　

eISSN： 2190-5444

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Abstract The availability of increasingly abundant mobility data in recent years has opened up new avenues for researchers to unravel human mobility patterns. Data aggregation methods have been introduced to gain a quantitative understanding of collective individual movements using these data. Nevertheless, the widely adopted origin–destination (OD) aggregation method for human mobility data lacks an essential piece of information: home location, which plays a vital role in characterizing individual movement patterns. In this study, we propose a novel data aggregation approach called home–origin–destination (HOD) with the aim of improving the accuracy of human mobility estimation. We compare the performance of various data aggregation methods for estimating population distribution. Our experimental results reveal more realistic mobility patterns when incorporating estimated home information, where individuals move out in the morning and return home before midnight. To further evaluate the effectiveness of the HOD approach, we conduct an entropy analysis to measure the unpredictability of human mobility. The HOD results exhibit lower entropy values than those in the other two cases, OD and home–destination (HD). These findings underscore the importance of incorporating home information in understanding and modeling human mobility. By leveraging the HOD data aggregation method, we can achieve more accurate population distribution estimates and capture the inherent dynamics of human movement
人流が創発する地理コネクティビティ

藤原直哉

地形　45　(1)　81-86　2024/02
Identifying sinks and sources of human flows: A new approach to characterizing urban structures

Takaaki Aoki, Shota Fujishima, Naoya Fujiwara

Environment and Planning B: Urban Analytics and City Science　51　(2)　419-437　2023/06/07
Publisher: SAGE Publications
DOI： 10.1177/23998083231180608 　

ISSN： 2399-8083

eISSN： 2399-8091

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Human flow data are rich behavioral data relevant to people’s decision-making regarding where to live, work, go shopping, etc., and provide vital information for identifying city centers. However, it is not as easy to understand massive relational data, and datasets have often been reduced merely to the statistics of trip counts at destinations, discarding relational information from origin to destination. In this study, we propose an alternative center identification method based on human mobility data. This method extracts the scalar potential field of human trips based on combinatorial Hodge theory. It detects not only statistically significant attractive locations as the sinks of human trips but also significant origins as the sources of trips. As a case study, we identify the sinks and sources of commuting and shopping trips in the Tokyo metropolitan area. This aim-specific analysis leads to a combinatorial classification of city centers based on the distinct aspects of human mobility. The proposed method can be applied to other mobility datasets with relevant properties and helps us examine the complex spatial structures in contemporary metropolitan areas from the multiple perspectives of human mobility.
人流データのネットワーク分析とその応用--最近の結果から

藤原直哉

関東都市学会年報　(24)　55-60　2023/03/31
A modified radiation model for human mobility: effects of distinct job-seeker expectation and job-offer benefit distributions Peer-reviewed

Yunhan Du, Naoya Fujiwara

Proceedings of 2022 International Symposium on Nonlinear Theory and Its Applications (NOLTA2022)　415-418　2022/12

DOI： 10.34385/proc.71.B4L-D-04 　
Influence of trip distance and population density on intra-city mobility patterns in Tokyo during COVID-19 pandemic Peer-reviewed

Kazufumi Tsuboi, Naoya Fujiwara, Ryo Itoh

PLOS ONE　17　(10)　e0276741-e0276741　2022/10/28
Publisher: Public Library of Science (PLoS)
DOI： 10.1371/journal.pone.0276741 　

eISSN： 1932-6203

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This study investigates the influence of infection cases of COVID-19 and two non-compulsory lockdowns on human mobility within the Tokyo metropolitan area. Using the data of hourly staying population in each 500m×500m cell and their city-level residency, we show that long-distance trips or trips to crowded places decrease significantly when infection cases increase. The same result holds for the two lockdowns, although the second lockdown was less effective. Hence, Japanese non-compulsory lockdowns influence mobility in a similar way to the increase in infection cases. This means that they are accepted as alarm triggers for people who are at risk of contracting COVID-19.
Urban spatial structures from human flow by Hodge–Kodaira decomposition Peer-reviewed

Takaaki Aoki, Shota Fujishima, Naoya Fujiwara

Scientific Reports　12　(1)　11258　2022/07/04
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-022-15512-z 　

eISSN： 2045-2322

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Abstract Human flow in cities indicates social activity and can reveal urban spatial structures based on human behaviours for relevant applications. Scalar potential is a mathematical concept that, when properly applied, can provide an intuitive view of human flow. However, the definition of such a potential in terms of the origin-destination flow matrix and its feasibility remain unresolved. In this case, we use Hodge–Kodaira decomposition, which uniquely decomposes a matrix into a potential-driven (gradient) flow and a curl flow. We depict the potential landscapes in cities resulting from commuting flow and reveal how the landscapes have either changed or remained unchanged by years or methods of transportation. We then determine how well the commuting flow is described by the potential, by evaluating the percentage of the gradient component for metropolitan areas in the USA and show that the gradient component is almost 100% in several areas; in other areas, however, the curl component is dominant, indicating the importance of circular flow along with triangles of places. The potential landscape provides an easy-to-use visualisation tool for showing the attractive places of human flow and will help in a variety of applications such as commerce, urban design, and epidemic spreading.
A model for simulating emergent patterns of cities and roads on real-world landscapes Peer-reviewed

Takaaki Aoki, Naoya Fujiwara, Mark Fricker, Toshiyuki Nakagaki

Scientific Reports　12　(1)　10093　2022/06/16
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-022-13758-1 　

eISSN： 2045-2322

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Abstract Emergence of cities and road networks have characterised human activity and movement over millennia. However, this anthropogenic infrastructure does not develop in isolation, but is deeply embedded in the natural landscape, which strongly influences the resultant spatial patterns. Nevertheless, the precise impact that landscape has on the location, size and connectivity of cities is a long-standing, unresolved problem. To address this issue, we incorporate high-resolution topographic maps into a Turing-like pattern forming system, in which local reinforcement rules result in co-evolving centres of population and transport networks. Using Italy as a case study, we show that the model constrained solely by topography results in an emergent spatial pattern that is consistent with Zipf’s Law and comparable to the census data. Thus, we infer the natural landscape may play a dominant role in establishing the baseline macro-scale population pattern, that is then modified by higher-level historical, socio-economic or cultural factors.
Analytical estimation of maximum fraction of infected individuals with one-shot non-pharmaceutical intervention in a hybrid epidemic model. International-journal Peer-reviewed

Naoya Fujiwara, Tomokatsu Onaga, Takayuki Wada, Shouhei Takeuchi, Junji Seto, Tomoki Nakaya, Kazuyuki Aihara

BMC Infectious Diseases　22　(1)　512-512　2022/06/01

DOI： 10.1186/s12879-022-07403-5 　

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BACKGROUND: Facing a global epidemic of new infectious diseases such as COVID-19, non-pharmaceutical interventions (NPIs), which reduce transmission rates without medical actions, are being implemented around the world to mitigate spreads. One of the problems in assessing the effects of NPIs is that different NPIs have been implemented at different times based on the situation of each country; therefore, few assumptions can be shared about how the introduction of policies affects the patient population. Mathematical models can contribute to further understanding these phenomena by obtaining analytical solutions as well as numerical simulations. METHODS AND RESULTS: In this study, an NPI was introduced into the SIR model for a conceptual study of infectious diseases under the condition that the transmission rate was reduced to a fixed value only once within a finite time duration, and its effect was analyzed numerically and theoretically. It was analytically shown that the maximum fraction of infected individuals and the final size could be larger if the intervention starts too early. The analytical results also suggested that more individuals may be infected at the peak of the second wave with a stronger intervention. CONCLUSIONS: This study provides quantitative relationship between the strength of a one-shot intervention and the reduction in the number of patients with no approximation. This suggests the importance of the strength and time of NPIs, although detailed studies are necessary for the implementation of NPIs in complicated real-world environments as the model used in this study is based on various simplifications.
Estimation of socioeconomic attributes from location information Peer-reviewed

Shohei Doi, Takayuki Mizuno, Naoya Fujiwara

Journal of Computational Social Science　4　(1)　187-205　2021/05
Publisher: Springer Science and Business Media LLC
DOI： 10.1007/s42001-020-00073-w 　

ISSN： 2432-2717

eISSN： 2432-2725

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<title>Abstract</title>Timely estimation of the distribution of socioeconomic attributes and their movement is crucial for academic as well as administrative and marketing purposes. In this study, assuming personal attributes affect human behavior and movement, we predict these attributes from location information. First, we predict the socioeconomic characteristics of individuals by supervised learning methods, i.e., logistic Lasso regression, Gaussian Naive Bayes, random forest, XGBoost, LightGBM, and support vector machine, using survey data we collected of personal attributes and frequency of visits to specific facilities, to test our conjecture. We find that gender, a crucial attribute, is as highly predictable from locations as from other sources such as social networking services, as done by existing studies. Second, we apply the model trained with the survey data to actual GPS log data to check the performance of our approach in a real-world setting. Though our approach does not perform as well as for the survey data, the results suggest that we can infer gender from a GPS log.
Chaos may enhance expressivity in cerebellar granular layer Peer-reviewed

Keita Tokuda, Naoya Fujiwara, Akihito Sudo, Yuichi Katori

Neural Networks　136　72-86　2021/04
Publisher: Elsevier BV
DOI： 10.1016/j.neunet.2020.12.020 　

ISSN： 0893-6080
Non-compulsory measures sufficiently reduced human mobility in Tokyo during the COVID-19 epidemic Peer-reviewed

Takahiro Yabe, Kota Tsubouchi, Naoya Fujiwara, Takayuki Wada, Yoshihide Sekimoto, Satish V. Ukkusuri

Scientific Reports　10　(1)　18053　2020/12
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-020-75033-5 　

eISSN： 2045-2322

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<title>Abstract</title>While large scale mobility data has become a popular tool to monitor the mobility patterns during the COVID-19 pandemic, the impacts of non-compulsory measures in Tokyo, Japan on human mobility patterns has been under-studied. Here, we analyze the temporal changes in human mobility behavior, social contact rates, and their correlations with the transmissibility of COVID-19, using mobility data collected from more than 200K anonymized mobile phone users in Tokyo. The analysis concludes that by April 15th (1 week into state of emergency), human mobility behavior decreased by around 50%, resulting in a 70% reduction of social contacts in Tokyo, showing the strong relationships with non-compulsory measures. Furthermore, the reduction in data-driven human mobility metrics showed correlation with the decrease in estimated effective reproduction number of COVID-19 in Tokyo. Such empirical insights could inform policy makers on deciding sufficient levels of mobility reduction to contain the disease.
Dynamical impacts of the coupling in a model of interactive infectious diseases Peer-reviewed

Patricio Olivares, Werner Creixell, Naoya Fujiwara

Chaos: An Interdisciplinary Journal of Nonlinear Science　30　(9)　093144-093144　2020/09
Publisher: AIP Publishing
DOI： 10.1063/5.0009452 　

ISSN： 1054-1500

eISSN： 1089-7682
Prediction of Student Performance in Abacus-Based Calculation Using Matrix Factorization Peer-reviewed

Keita Tokuda, David Kaschu, Takuma Ota, Yasunobu Hashimoto, Naoya Fujiwara, Akihito Sudo

UMAP '20 Adjunct: Adjunct Publication of the 28th ACM Conference on User Modeling, Adaptation and Personalization　114-118　2020/07

DOI： 10.1145/3386392.3399309 　
Evaluation of Mental Calculation Educational System with Invisible Abacus Peer-reviewed

Keita Tokuda, Yasunobu Hashimoto, Chika Yamauchi, Keiko Iwasa, Kazuki Yoshida, Naoya Fujiwara, Akihito Sudo

Proceedings of the 2020 8th International Conference on Information and Education Technology　161-168　2020/03/28
Publisher: ACM
DOI： 10.1145/3395245.3396417 　
Effects of infection control policies on the final size

藤原直哉, 藤原直哉, 翁長朝功, 翁長朝功, 和田崇之, 合原一幸

生産研究　72　(2)　141-143　2020/03

DOI： 10.11188/seisankenkyu.72.141 　

ISSN： 0037-105X
Development of patient-specific 1D-0D simulation based on MRI and SPECT data

Hao Zhang, Naoya Fujiwara, Masaharu Kobayashi, Shigeki Yamada, Fuyou Liang, Shu Takagi, Marie Oshima

Journal of Biorheology　32　(1)　2-8　2018
Publisher: Japanese Society of Biorheology
DOI： 10.17106/jbr.32.2 　

ISSN： 1867-0474 1867-0466
Smoothing effect for spatially distributed renewable resources and its impact on power grid robustness Peer-reviewed

Motoki Nagata, Yoshito Hirata, Naoya Fujiwara, Gouhei Tanaka, Hideyuki Suzuki, Kazuyuki Aihara

CHAOS　27　(3)　033104　2017/03

DOI： 10.1063/1.4977510 　

ISSN： 1054-1500

eISSN： 1089-7682
A perturbation-theoretic approach to Lagrangian flow networks Peer-reviewed

Naoya Fujiwara, Kathrin Kirchen, Jonathan F. Donges, Reik V. Donner

CHAOS　27　(3)　2017/03

DOI： 10.1063/1.4978549 　

ISSN： 1054-1500

eISSN： 1089-7682
Development of a Numerical Method for Patient-Specific Cerebral Circulation Using 1D-0D Simulation of the Entire Cardiovascular System with SPECT Data Peer-reviewed

Hao Zhang, Naoya Fujiwara, Masaharu Kobayashi, Shigeki Yamada, Fuyou Liang, Shu Takagi, Marie Oshima

ANNALS OF BIOMEDICAL ENGINEERING　44　(8)　2351-2363　2016/08

DOI： 10.1007/s10439-015-1544-8 　

ISSN： 0090-6964

eISSN： 1573-9686
The role of asymmetrical and repulsive coupling in the dynamics of two coupled van der Pol oscillators Peer-reviewed

Sergey Astakhov, Artem Gulai, Naoya Fujiwara, Juergen Kurths

CHAOS　26　(2)　2016/02

DOI： 10.1063/1.4940967 　

ISSN： 1054-1500

eISSN： 1089-7682
Clustering of human mobility networks in cities

Fujiwara Naoya, Akiyama Yuki, Fujishima Shota, Shibasaki Ryosuke

Meeting Abstracts of the Physical Society of Japan　71　2908-2908　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.2.0_2908 　
Detecting early warning signals for blackouts in power grids from the viewpoint of nonlinear dynamics Peer-reviewed

Motoki Nagata, Yoshito Hirata, Naoya Fujiwara, Gouhei Tanaka, Hideyuki Suzuki, Kazuyuki Aihara

International Symposium on Nonlinear Theory and its Applications (NOLTA2015)　22-25　2015/12

DOI： 10.34385/proc.47.A2L-B-2 　
Perturbation theory for unstable periodic orbits in chaotic dynamical systems Peer-reviewed

Naoya Fujiwara, Miki U. Kobayashi, Kazuyuki Aihara

International Symposium on Nonlinear Theory and its Applications (NOLTA2015)　229-232　2015/12

DOI： 10.34385/proc.47.A4L-A-4 　
Communities in an inter-firm network and their geographical perspectives Peer-reviewed

Ritsu Sakuramachi, Naoya Fujiwara, Shota Fujishima, Yuki Akiyama, Ryosuke Shibasaki

14th International Conference on Computers in Urban Planning and Urban Management (CUPUM 2015)　2015　371-100144　2015/07
Publisher: The Association of Japanese Geographers
DOI： 10.14866/ajg.2015s.0_100144 　
An approximation for dynamical processes on periodic temporal networks Peer-reviewed

Fujiwara Naoya

IEICE NONLINEAR THEORY AND ITS APPLICATIONS　6　(2)　295-302　2015

DOI： 10.1587/nolta.6.295 　

ISSN： 2185-4106
Interdisciplinary challenges in the study of power grid resilience and stability and their relation to extreme weather events Peer-reviewed

J. Heitzig, N. Fujiwara, K. Aihara, J. Kurths

European Physical Journal: Special Topics　223　(12)　2383-2386　2014/10/01
Publisher: Springer Verlag
DOI： 10.1140/epjst/e2014-02281-0 　

ISSN： 1951-6401 1951-6355
Node-wise robustness against fluctuations of power consumption in power grids Peer-reviewed

Motoki Nagata, Naoya Fujiwara, Gouhei Tanaka, Hideyuki Suzuki, Eiichi Kohda, Kazuyuki Aihara

EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS　223　(12)　2549-2559　2014/10

DOI： 10.1140/epjst/e2014-02215-x 　

ISSN： 1951-6355

eISSN： 1951-6401
Network analysis of transport phenomena in flow fields Peer-reviewed

Naoya Fujiwara

International Symposium on Nonlinear Theory and its Applications (NOLTA2013)　314-37　2013/09

DOI： 10.15248/proc.2.314 　
Phase-Model Analysis of Supply Stability in Power Grid of Eastern Japan Peer-reviewed

Motoki Nagata, Naoya Fujiwara, Isao Nishikawa, Gouhei Tanaka, Hideyuki Suzuki, Kazuyuki Aihara

International Symposium on Nonlinear Theory and its Applications (NOLTA2013)　69-72　2013/09

DOI： 10.15248/proc.2.69 　
Hopf bifurcation and multistability in a system of phase oscillators Peer-reviewed

Sergey Astakhov, Naoya Fujiwara, Artem Gulay, Naofumi Tsukamoto, Juergen Kurths

Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics　88　(3)　032908　2013/09

DOI： 10.1103/PhysRevE.88.032908 　

ISSN： 1539-3755
Towards dynamical network biomarkers in neuromodulation of episodic migraine Peer-reviewed

Markus A. Dahlem, Sebastian Rode, Arne May, Naoya Fujiwara, Yoshito Hirata, Kazuyuki Aihara, Jürgen Kurths

Translational Neuroscience　4　(3)　282-294　2013/09

DOI： 10.2478/s13380-013-0127-0 　

ISSN： 2081-3856 2081-6936
A detection method of symmetry restoration process of attractor merging crisis Peer-reviewed

T. Mizuguchi, M. Yomosa, N. Fujiwara, M. U. Kobayashi

EUROPEAN PHYSICAL JOURNAL B　85　(7)　230-237　2012/07

DOI： 10.1140/epjb/e2012-21037-0 　

ISSN： 1434-6028
Complete synchronization of chaotic atmospheric models by connecting only a subset of state space Peer-reviewed

P. H. Hiemstra, N. Fujiwara, F. M. Selten, J. Kurths

NONLINEAR PROCESSES IN GEOPHYSICS　19　(6)　611-621　2012

DOI： 10.5194/npg-19-611-2012 　

ISSN： 1023-5809
Spectral Analysis of Synchronization in Mobile Networks Peer-reviewed

Naoya Fujiwara, Juergen Kurths, Albert Diaz-Guilera

NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2011: INTERNATIONAL CONFERENCE ON NUMERICAL ANALYSIS AND APPLIED MATHEMATICS, VOLS A-C　1389　2011

DOI： 10.1063/1.3637782 　

ISSN： 0094-243X
Scytale decodes chaos: A method for estimating unstable symmetric solutions Peer-reviewed

Yasuaki Morita, Naoya Fujiwara, Miki U. Kobayashi, Tsuyoshi Mizuguchi

CHAOS　20　(1)　2010/03

DOI： 10.1063/1.3365053 　

ISSN： 1054-1500
Dynamics in the anisotropic XY model driven by dichotomous Markov noise Peer-reviewed

Katsuya Ouchi, Takehiko Horita, Naofumi Tsukamoto, Naoya Fujiwara, Hirokazu Fujisaka

PHYSICAL REVIEW E　78　(2)　2008/08

DOI： 10.1103/PhysRevE.78.021139 　

ISSN： 1539-3755

eISSN： 1550-2376
Magnetic domain wall dynamics associated with the dynamic phase transition Peer-reviewed

N Fujiwara, H Tutu, H Fujisaka

PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT　(161)　181-184　2006

DOI： 10.1143/PTPS.161.181 　

ISSN： 0375-9687
Magnetic walls in the anisotropic XY-spin system in an oscillating magnetic field Peer-reviewed

N Fujiwara, H Tutu, H Fujisaka

PHYSICAL REVIEW E　70　(6)　066132　2004/12

DOI： 10.1103/PhysRevE.70.066132 　

ISSN： 1539-3755

eISSN： 1550-2376
Landau theory of dynamic phase transitions and systematic perturbation expansion method for getting phase diagrams Peer-reviewed

H Tutu, N Fujiwara

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　73　(10)　2680-2696　2004/10

DOI： 10.1143/JPSJ.73.2680 　

ISSN： 0031-9015

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Misc. 30

21aBS-7 Percolation-like transition in human mobility networks

Fujiwara N, Sonawane Abhijeet R, Iwayama K, Aihara K

Meeting Abstracts of the Physical Society of Japan　71　(0)　2994-2994　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.1.0_2994 　

ISSN： 2189-079X
A simulation study of a mobile oscillator network with fixed nodes

OSHIMA Yuki, FUJIWARA Naoya, AIHARA Kazuyuki, ANDO Hiroyasu

SEISAN KENKYU　68　(3)　247-250　2016
Publisher: Institute of Industrial Science The University of Tokyo
DOI： 10.11188/seisankenkyu.68.247 　

ISSN： 0037-105X

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A mobile oscillator network, which is a kind of temporal networks, is of interest due to a variety of its applications such as mobile communication. In this study, we investigate the time required for synchronization of all the nodes in a mobile oscillator network, especially regarding effects of fixed nodes on the synchronization time. According to our simulation, there exists an optimal ratio of the number of fixed nodes to that of mobile ones in order to reduce the synchronization time. Furthermore, we analytically estimate the synchronization time with respect to the number of fixed nodes.
Effect of fixed nodes on synchronization in mobile oscillator networks

115　(300)　29-33　2015/11/09
Publisher: 電子情報通信学会
ISSN： 0913-5685
16pCW-8 Analysis of the size of infection spread using the people flow data II

Fujiwara N, Sonawane A.R, Iwayama K, Aihara K

Meeting Abstracts of the Physical Society of Japan　70　(0)　2590-2590　2015
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.70.2.0_2590 　

ISSN： 2189-079X
30aPS-61 Simulation of the spread of infectious diseases using human mobility data

Urabe Chiyori, Fujiwara Naoya, Suzuki Shin'ichiro, Akita Junichi, Iwayama Koji, Fujii Fumiyuki, Aihara Kazuyuki

Meeting Abstracts of the Physical Society of Japan　69　(0)　373-373　2014
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
10aAP-5 Analysis of the size of infection spread using the people flow data

Fujiwara N, Sonawane Abhijeet R, Iwayama K, Aihara K

Meeting Abstracts of the Physical Society of Japan　69　(0)　175-175　2014
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
AS-1-1 ANALYTIC FRAMEWORK FOR INFORMATION TRANSMISSION IN MOBILE NETWORKS

Fujiwara Naoya, Aihara Kazuyuki

Proceedings of the IEICE General Conference　2013　"S-1"-"S-2"　2013/03/05
Publisher: The Institute of Electronics, Information and Communication Engineers
27pXM-8 Perturbation theory of unstable periodic orbits in chaotic dynamical systems

Fujiwara N, Kobayashi M. U, Aihara K

Meeting Abstracts of the Physical Society of Japan　68　(0)　360-360　2013
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Analysis of Frequency Synchronization of the Power Grid in East Japan Using the Phase Model

NAGATA Motoki, FUJIWARA Naoya, NISHIKAWA Isao, TANAKA Gouhei, SUZUKI Hideyuki, AIHARA Kazuyuki

SEISAN KENKYU　65　(3)　295-299　2013
Publisher: Institute of Industrial Science The University of Tokyo
DOI： 10.11188/seisankenkyu.65.295 　

ISSN： 0037-105X

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After the Tohoku earthquake, it is becoming very important to ensure a stable energy supply because of the recent developments in renewable and decentralized energy. In order to stabilize the supply of power grids, it is useful to analyze mathematical models which describe the essence of dynamical processes of the grids. In this paper, we replicated the topology of the power grid in Eastern Japan and described power grids by phase models. We used the minimum coupling strength for global frequency synchronizationas a stability measure in power grids. Further, we identify transmission lines which contribute to a stable supply.
25aTH-2 Synchronization in networks of mobihle oscillators

Fujiwara N., Kurths J., Diaz-Guilera A.

Meeting abstracts of the Physical Society of Japan　65　(2)　278-278　2010/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22aVB-5 Detection of unstable periodic orbits from chaotic time series II

Morita Yasuaki, Mizuguchi Tsuyoshi, Fujiwara Naoya, Kobayashi Miki

Meeting abstracts of the Physical Society of Japan　63　(2)　232-232　2008/08/25
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Prof. Hirokazu Fujisaka and Pattern Dynamics

MIYAZAKI S, TUTU H, FUJIWARA N, TSUKAMOTO N

形の科学会誌 = Bulletin of the Society for Science on Form　22　(2)　207-208　2007/11/01

ISSN： 0915-6089
24aPS-42 Large deviation analysis of undirected networks

Miyazaki S, Ejima K, Fujiwara N

Meeting abstracts of the Physical Society of Japan　62　(2)　329-329　2007/08/21
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
21aPS-33 Pattern dynamics in a rotating external field II

Fujiwara N., Kobayashi T., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　62　(1)　307-307　2007/02/28
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
21aPS-48 Dynamics in the anisotropic XY spin system driven by the dichotomous markov noise II

Ouchi K., Tsukamoto N., Fujiwara N., Horita T., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　62　(1)　310-310　2007/02/28
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
回転外力に駆動されるパターンの動力学(生命リズムと振動子ネットワーク)

藤原直哉, 小林丈朗, 藤坂博一

物性研究　87　(4)　621-621　2007
Publisher: 物性研究刊行会
ISSN： 0525-2997
26aPS-27 Dynamics in the anisotropic spin system driven by the dichotomous markov noise

Ouchi K., Tsukamoto N., Fujiwara N., Horita T., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　61　(2)　235-235　2006/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
23aXG-3 Pattern dynamics in a rotating external field

Fujiwara N., Kobayashi T., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　61　(2)　174-174　2006/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
23aXG-1 Torus-torus transition in the spin system under rotating magnetic field

Kobayashi T., Fujiwara N., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　61　(2)　174-174　2006/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29pRD-5 Kink dynamics in the periodic and the static external fields

Fujiwara N., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　61　(1)　294-294　2006/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29pRD-4 Spatio-temporal dynamics in the anisotropic XY spin system in a rotating magnetic field

Kobayashi T., Fujiwara N., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　61　(1)　294-294　2006/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22aPS-45 Dynamic phase transition and chaotic response

Fujiwara N., Kobayashi T., Tutu H., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　60　(2)　211-211　2005/08/19
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22aYO-3 Dynamic phase transition in the anisotoropic XY spin system in a rotating magnetic field

Kobayashi T., Fujiwara N., Tutu H., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　60　(2)　200-200　2005/08/19
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
27aPS-28 Dynamic phase transition in the Heisenberg ferromagnet under oscillating magnetic field (II)

Fujiwara N., Kobayashi T., Tutu H., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　60　(1)　324-324　2005/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
14aTC-6 Dynamic phase transitions of Heisenberg ferromagnet under osicllating magnetic field

Fujiwara N, Tutu H, Fujisaka H

Meeting abstracts of the Physical Society of Japan　59　(2)　232-232　2004/08/25
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29pPSA-38 Perturbation method for getting phase diagram in dynamic phase transition

Tutu H., Fujiwara N.

Meeting abstracts of the Physical Society of Japan　59　(1)　327-327　2004/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Kink dynamics associated with dynamic phase transitions

Fujiwara N., Tutu H., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　58　(2)　210-210　2003/08/15
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Ising-Bloch transition in an oscillating magnetic field

Fujiwara N., Tutu H., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　58　(1)　300-300　2003/03/06
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Dynamic Phase transition and ordering process in the XY model

Fujiwara N., Tutu H., Fujisaka H.

Meeting abstracts of the Physical Society of Japan　57　(2)　209-209　2002/08/13
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Contribution of hidden modes to nonlinear epidemic dynamics in urban human proximity networks

Naoya Fujiwara, Abhijeet R. Sonawane, Koji Iwayama, Kazuyuki Aihara

arXiv　1512.01901

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Books and Other Publications 3

ネットワーク科学入門 Pythonで学ぶデータ分析とモデリング

笹原和俊, 五十嵐佑, 小林照義, 瀧川裕貴, 橋本康弘, 藤原直哉, 宮下修人, 村瀬洋介

丸善出版　2023/12

ISBN: 9784621308981
ツイートを用いた人流ネットワーク分析

藤原直哉

古今書院　2019/11
ツイッターの空間分析

桐村喬, 編, 藤原直哉

古今書院　2019/11

ISBN: 9784772253291

Presentations 121

都市の創発シミュレーション：確率的エージェントベースモデルによる分析

小平航大, 坪井和史, 藤原直哉

ネットワーク生態学グループ創立20周年記念シンポジウム　2025/03/08

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ポスター番号 14
確率的エージェントベースモデルを用いた都市形成のシミュレーション

小平航大, 坪井和史, 藤原直哉

ネットワーク科学研究会2024　2025/03/04

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ポスター番号 30
Exploring the functional role of directional intermodular coupling through in vitro experiments and in silico modeling

Nobuaki Monma, Hideaki Yamamoto, Naoya Fujiwara, Hakuba Murota, Satoshi Moriya, Ayumi Hirano-Iwata, Shigeo Sato

The 13th RIEC International Symposium on Brain Functions and Brain Computer (BFBC2025)　2025/02/27
Mobility Patterns of Trailers Around International Container Terminals: A Case Sutdy in Sendai Port, Japan International-presentation

Huixuan Zheng, Chenbo Zhao, Yoshiki Ogawa, Ryuichi Shibasaki, Naoya Fujiwara

IEEE BigData 2024, Synergizing Mobility Data for Creating and Discovering Valuable Places　2024/12/18

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https://www3.cs.stonybrook.edu/~ieeebigdata2024/BD2024-Program-Schedule.pdf
育児中の親の行動パターンと接触経験:人流データを用いた実証研究

林秀星, 矢部貴大, 藤原直哉

第38回応用地域学会研究発表大会　2024/11/30
仙台港湾部における国際海上コンテナ用セミトレーラのモビリティ分析

藤原直哉, 鄭慧萱, 趙琛渤, 小川芳樹, 柴崎隆一

第70回土木計画学会・秋大会　2024/11/17
マルコフ連鎖モデルによる神経細胞ネットワークの構造機能相関解析

門間信明, 山本英明, 藤原直哉, 佐藤茂雄

ニューロコンピューティング研究会　2024/09/28
City size distribution associated with percolation simulation

Yuzan Liu, Takaaki Aoki, Naoya Fujiwara

NetSci2024　2024/06/19
Exploring the Impacts of the Complex Interplay Between Waning Immunity and Disease Fatality on the Topology of Scale Free Networks International-presentation

Ikpe ThankGod, Naoya Fujiwara

Seventh Northeast Regional Conference of Complex Systems (NERCSS 2024)　2024/03/21
Pattern recognition through synchronization to oscillatory inputs in chaotic neural networks

Keita Tokuda, Naoya Fujiwara

The 12th RIEC International Symposium on Brain Functions and Brain Computer (BFBC2024)　2024/02/27

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P-10
Designing modular neuronal networks with directional connections to enhance dynamical complexity International-presentation

Nobuaki Monma, Hideaki Yamamoto, Hakuba Murota, Satoshi Moriya, Naoya Fujiwara, Ayumi Hirano-Iwata, Shigeo Sato

The 12th RIEC International Symposium on Brain Functions and Brain Computer　2024/02/27
City size distribution by percolation simulation on Japan real terrain

Yuzan Liu, 青木高明, 藤原直哉

2023/12/23
Effects of Epidemics Dynamics with Births and Deaths on the Topology of a Scale Free Network

ThankGod IfrekeSylvanus Ikpe, Naoya Fujiwara

2023/12/23
Beyond origin-destination: Home information in mobility data aggregation

2023/12/23
A survey on social interaction via proximity detection

2023/12/09
Geographical connectivity emerging from human mobility Invited

Naoya Fujiwara

GEOCONNECTIVITY2023　2023/11/22
Exploring interplay between structure of urban proximity networks and spread of infectious diseases based on social surveys International-presentation

Naoya Fujiwara, Akihiro Fujihara, Mao Wei, Takayuki Wada, Tomoya Hanibuchi, Tomoki Nakaya, Kazuyuki Aihara

NetMob2023　2023/10/05
A comparative analysis of aggregation methods for human mobility data International-presentation

Yunhan Du, Takaaki Aoki, Naoya Fujiwara

NetMob2023　2023/10/05
機械学習によるインフルエンザウイルス細胞変性効果自動判定技術の構築

水田克巳, 瀬戸順次, 藤原直哉, 青木洋子, 佐々木美香, 駒林賢一, 昆美也子, 鈴木優子, 大槻りつ子

第70回日本ウイルス学会学術集会　2023/09/26

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発表番号 P-379
指向性結合を有する神経細胞ネットワークのin vitro-in silico モデリング

門間信明, 山本英明, 室田白馬, 守谷哲, 藤原直哉, 平野愛弓, 佐藤茂雄

第84回応用物理学会秋季学術講演会　2023/09/21
Potential field of human flow extracted by Hodge-Kodaira decomposition International-presentation

Takaaki Aoki, Shota Fujishima, Naoya Fujiwara

International Congress on Industrial and Applied Mathematics（ICIAM2023）　2023/08/24

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[01202] Analysis and modelling of human flows[02895]
Towards science of multi-scale human flow International-presentation

Naoya Fujiwara

International Congress on Industrial and Applied Mathematics（ICIAM2023）　2023/08/24

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[01202] Analysis and modelling of human flows[03549]
Potential landscape of human flow in cities

Takaaki Aoki, Shota Fujishima, Naoya Fujiwara

STATPHYS 28　2023/08/10
A model of city formation and scaling laws International-presentation

Yuzan Liu, Takaaki Aoki, Naoya Fujiwara

STATPHYS 28　2023/08/08
人流データの複雑ネットワーク分析とその応用 Invited

藤原直哉

第44回数学入門公開講座　2023/08/03
Potential landscape of human flow in cities

Takaaki Aoki, Shota Fujishima, Naoya Fujiwara

NetSci2023　2023/07/14

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27
Scaling laws associated with percolation transition in the city size distribution

Yuzan Liu, Takaaki Aoki, Naoya Fujiwara

NetSci2023　2023/07/14

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25
Characteristics of urban proximity networks based on Bluetooth signals International-presentation

Naoya Fujiwara, Akihiro Fujihara, Takayuki Wada, Tomoya Hanibuchi, Tomoki Nakaya, Kazuyuki Aihara

NetSci2023 Satellite, Epidemic control: from mobility data to public health　2023/07/11
地形効果を考慮した都市の数理モデル

藤原直哉

RIMS共同研究「人口と環境の数理地理モデリング」　2023/06/15
Intersections of Nonlinearity and Networks in Human Mobility Data Invited

Naoya Fujiwara

IUTAM Symposium on Data-driven Nonlinear and Stochastic Dynamics with the Control　2023/06/08
Human mobility networks and their applications

Naoya Fujiwara

NONLINEAR DATA ANALYSIS AND MODELING: ADVANCES, APPLICATIONS, PERSPECTIVES　2023/03/15
Robustness of the scaling laws in the city size distribution

Yuzan Liu, Takaaki Aoki, Naoya Fujiwara

2023/03/08
機械学習を用いたインフルエンザウイルスの培養細胞に対する細胞変性効果の有無の判定

瀬戸順次, 青木洋子, 佐々木美香, 駒林賢一, 水田克巳, 藤原直哉, 昆美也子, 鈴木優子, 大槻りつ子

第49回山形県公衆衛生学会　2023/03/01
都市規模分布はスケーリング則に従うか？

藤原直哉, 劉雨瓚, 青木高明

応用地域学会第36回研究発表大会　2022/12/18

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4-6A
A Modified Radiation Model for Human Mobility: Effects of Distinct Job-Seeker Expectation and Job-Offer Benefit Distributions International-presentation

Yunhan Du, Naoya Fujiwara

2022 International Symposium on Nonlinear Theory and Its Applications　2022/12/13
高解像度な空間単位でのCOVID-19流行予測アプリケーションの開発

永田彰平, 足立浩基, 藤原直哉, 中谷友樹

第31回地理情報システム学会研究発表大会　2022/10/29
コロナ禍における人流分析 Invited

藤原直哉

関東都市学会シンポジウム　2022/05/29

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大会テーマ「新型コロナ禍と都市―現場からの提示を踏まえた再考―」
感染症ダイナミクスと人流分析

藤原直哉

地理情報システム学会東北支部 2021年年度研究交流会　2022/03/22
Response to severe disasters revealed by the human mobility data Invited

Naoya Fuijwara

JICA Innovative Asia JFY 2021 (Big data and Sustainable Development Goals (SDGs)) NO. 201702823-J041　2022/02/14
Branching process 理論によるリツイート活動の予測

楊氷潔, 藤原直哉, 翁長朝功

ネットワーク科学研究会2021　2021/12/11
Consumer preferences and multiple innovations in time-evolving product variety networks

Yunhan Du, Yoshinori Tone, Akihito Sudo, Naoya Fujiwara

2021/12/11
Urban spatial structures from human flow by Hodge-Kodaira decomposition

2021/11/20
Does COVID-19 pandemic change our daily mobility? Evidence from Japanese cellar-phone data

2021/11/20
Toward understanding the roles of consumer preferences in innovation processes

Du Yunhan, Yoshinori Tone, Akihito Sudo, Naoya Fujiwara

2021/11/20
人流データに基づく都市空間構造の可視化: OD行列のHodge-小平分解

青木高明, 藤嶋翔太, 藤原直哉

CSIS DAYS 2021　2021/11/20

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講演番号 C07
人流データを利用したCOVID-19流行の微細な時空間モデル

中谷友樹, 足立浩基, 永田彰平, 藤原直哉

地理情報システム学会第30回学術研究発表大会　2021/10/30

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ポスター番号12
Does COVID-19 pandemic change our daily mobility? Evidence from Japanese celler-phone data

Kazufumi Tsuboi, Naoya Fujiwara, Ryo Itoh

11thThe Asian Seminar in Regional Science (ASRS)　2021/10/08
ホッジ・小平分解を用いた,人流データの背後にあるポテンシャル場の決定

青木高明, 藤嶋翔太, 藤原直哉

日本物理学会　2021/09/21

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21pL2-10
A network model of consumer preferences and firm innovation International-presentation

Yunhan Du, Yoshihiro Tone, Akihito Sudo, Naoya Fujiwara

NETWORKS 2021　2021/07/05

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Presentation number: 10175
Network analysis of human mobility and impact of COVID-19 pandemic on human mobility

Kazufumi Tsuboi, Naoya Fujiwara, Ryo Itoh

2021/06/24
Mobility change and COVID-19: Evidence from the cellular-phone data in Tokyo International-presentation

Kazufumi Tsuboi, Naoya Fujiwara, Ryo Itoh

The XV World Conference of Spatial Econometrics Association (SEA 2021)　2021/05/28

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Session [8-A-03],PaperID C000048
地理情報データ解析と複雑ネットワーク Invited

藤原直哉

シンポジウム：先端数理科学の目指すもの現象にかかわる「理」を理解する　2021/03/18
A novel scenario for innovation: Consumer preference matters

Yunhan Du, Yoshinori Tone, Akihito Sudo, Naoya Fujiwara

2020/12/17
人流ネットワーク分析とその周辺

藤原直哉

ネットワーク科学セミナー2020　2020/12/18
感染抑制介入の数理モデル:経済的影響の評価に向けて

藤原直哉, 翁長朝功, 和田崇之, 竹内昌平, 瀬戸順次, 中谷友樹, 合原一幸

第 34 回応用地域学会研究発表大会　2020/11/29
全国レベルでみたジオタグ付きツイートに用いられる地名の空間分布

桐村喬, 藤原直哉, 平岡喬之

CSIS DAYS 2020　2020/11/21
Analysis of temporal and mobility networks

Naoya Fujiwara

The 8th RIEC International Symposium on Brain Functions and Brain Computer　2020/02/15
Mobility networks and distribution of location-specific nouns in geo-tagged tweets International-presentation

Naoya Fujiwara, Takashi Kirimura, Takayuki Hiraoka

NetSci-X 2020　2020/01/20

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poster number 113
Theoretical Modeling of Information Transmission in Visual Systems International-presentation

Naoya Fujiwara

2019 International Symposium on Nonlinear Theory and its Applications (NOLTA2019)　2019/12/04
災害時におけるリアルタイム人流データの解析

藤原直哉, 矢部貴大, 坪内孝太, 関本義秀, Satish V. Ukkusuri

第 33 回応用地域学会研究発表大会　2019/11/24

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D-7-3
ジオタグ付きツイートで用いられる名詞の空間分布

藤原直哉, 桐村喬, 平岡喬之

CSIS DAYS 2019　2019/11/16
Word Embeddingsを用いた斬新さと手堅さを兼ね備えた経済学における研究テーマの自動生成

渡辺星, 藤原直哉, 須藤明人

第17回情報学ワークショップ　2019/11/02
ジオタグ付きツイートで用いられる名詞の空間的広がりと階層性－京都市における事例分析－

桐村喬, 藤原直哉, 平岡喬之

地理情報システム学会第28回学術研究発表大会　2019/10/20
Tracking spreading events through human mobility data and networks

Naoya Fujiwara

Mathematical modeling and models of population dynamics in biological and social systems　2019/10/08
人流データ解析とネットワーク

藤原直哉

第75回情報科学談話会　2019/08/01
Complex networks of human mobility and their applications International-presentation

Naoya Fujiwara

A3 Foresight Program workshop "Modeling and Simulation of Hierarchical and Heterogeneous Flow Systems with Applications to Materials Science Ⅵ"　2019/07/28
地理空間情報・ネットワーク・数理モデル Invited

藤原直哉

第9回数理モデリング研究会　2019/07/20
Understanding Post-Disaster Population Recovery Patterns International-presentation

Takahiro Yabe, Kota Tsubouchi, Naoya Fujiwara, Yoshihide Sekimoto, Satish V. Ukkusuri

Netmob2019　2019/07/10
人流ビッグデータ解析による、突発事象に対する社会の応用解析

藤原直哉

RIMS共同研究「数理地理モデリングと人口データ解析による環境人文学の展開」　2019/06/27
Rare Events Associated with Human Mobility International-presentation

Naoya Fujiwara

SIAM Conference on Applications of Dynamical Systems (DS19)　2019/05/23
地理空間データを用いた社会経済現象解析 Invited

藤原直哉

経済・社会への分野横断的研究会　2018/12/04
Pattern formation and co-existence of steady states in a co-evolving model of cities and roads

Naoya Fujiwara

ARSC2018　2018/12/01
ネットワーク科学・情報科学による人流解析の可能性 Invited

藤原直哉

人文地理学会大会第64回都市圏研究部会　2018/11/24
Towards Prediction of Complex Geospatial Phenomena International-presentation Invited

Naoya Fujiwara

ACM SIGSPATIAL 2018 Workshop on Prediction of Human Mobility (PredictGIS2018)　2018/11/06
実地形上における都市と道路のパターン形成

青木高明, 藤原直哉, 中垣俊之

2018/09/11
Dynamical processes on periodic temporal networks and their applications International-presentation

Naoya Fujiwara, Abhijeet R. Sonawane

International Symposium on Nonlinear Theory and its Applications (NOLTAS2018)　2018/09/03
人の流動のネットワーク解析と空間情報科学 Invited

藤原直哉

CSIS DAYS 2017　2017/12/01
Contribution of hidden modes to nonlinear epidemic dynamics in urban human proximity networks International-presentation

Naoya Fujiwara, Abhijeet R. Sonawane, Koji Iwayama, Kazuyuki Aihara

NetSci2017 Satellite, Urban Systems and Network Science　2017/06/19
Graph clustering of human mobility networks and its applications International-presentation

Naoya Fujiwara

Dynamics Days 2017　2017/01/06
ネットワーククラスタリングとしての都市圏域構造

藤原直哉

CSIS DAYS 2016　2016/11/18
人の流動ネットワークのクラスタリングの属性に対する依存性

藤原直哉

複雑コミュニケーションサイエンス研究会　2016/11/04
人流データのクラスタリング手法に対する一考察

藤原直哉

第25回地理情報システム学会学術研究発表大会　2016/10/16
都市圏における人流ネットワークのクラスタリング

藤原直哉, 秋山祐樹, 藤嶋翔太, 柴崎亮介

日本物理学会2016年秋季大会　2016/09/16
人流ネットワークのクラスタリングによる圏域検出と感染症拡大モデル

藤原直哉, 桜町律, 秋山祐樹, 藤嶋翔太, 金田穂高, 柴崎亮介

，CCS/NetSci 合同ワークショップ in 北海道　2016/08/09
人の流れネットワークにおけるパーコレーション的転移

藤原直哉, Abhijeet R. Sonawane, 岩山幸治, 合原一幸

日本物理学会2016 年年次大会　2016/03/21
人の移動データを用いた社会現象ダイナミクス解析

藤原直哉, Abhijeet R. Sonawane, 岩山幸治, 合原一幸

社会物理学の現代的課題　2016/01/08
都市圏における人の流動データによる感染症伝播のネットワーク解析

藤原直哉

複雑ネットワーク・サマースクール2014　2014/08/10
モバイルネットワーク上での情報伝播ダイナミクス

藤原直哉

情報ネットワーク科学研究会・複雑コミュニケーションサイエンス研究会合同ワークショップ　2013/08/09
人の流れデータによる動的ネットワーク上での情報伝播解析

藤原直哉, 合原一幸

IEICE-HPB公開シンポジウム「ヒューマンプローブの新たな展開」　2012/11/16
パーソントリップデータと数理モデルによる、動的ネットワーク上での情報伝播解析

藤原直哉, 合原一幸

CSIS DAYS 2012　2012/11/03
Synchronization in mobile networks: Model and face-to-face communication networks

Naoya Fujiwara, Kazuyuki Aihara

International Conference on Towards Mathematical Foundations of Complex Network Theory　2012/09/15
Synchronization of Networks with Time Evolving Topology

Naoya Fujiwara

The 2nd International Symposium on Innovative Mathematical Modelling　2012/05/15
Estimation of optimal coupling functions for synchronization of coupled chaotic oscillators

Naoya Fujiwara, J, ̈urgen Kurths

AGU Fall Meeting (　2011/12/05
Information spreading and synchronization in mobile networks International-presentation

Naoya Fujiwara, J, ̈urgen Kurths, Albert D ́ıaz-Guilera

XXXI Dynamics Days Europe　2011/09/13
Synchronization and its breakdown in mobile oscillator networks

Naoya Fujiwara, J, ̈urgen Kurths, Albert D ́ıaz-Guilera

Engineering of Chemical Complexity　2011/07/06
Parameter estimation of nonlinear dynamical systems using synchronization International-presentation

Naoya Fujiwara, J, ̈urgen Kurths

EGU general assembly 2011　2011/04/06
Synchronization dynamics in mobile oscillator networks International-presentation

Future Internet, Society, A Complex, Systems Perspective

2010/10/03
モバイルネットワークにおける同期現象

藤原直哉, Ju, ̈gen Kurths, Albert D ́ıaz-Guilera

日本物理学会 2010 年秋季大会 25aTH-2　2010/09/25
Synchronization of networks of mobile oscillators International-presentation

Naoya Fujiwara

IV International Congress/Networks: A framework for cross disciplinary applications　2010/02/05
Spectral analysis of chaotic synchronization in non-identical oscillator networks International-presentation

Naoya Fujiwara, J, ̈urgen Kurths

Conference on Dynamics in Systems Biology　2009/09/14
準周期振動子の位相ダイナミクス

藤原直哉, 小林, 丈朗, 藤坂博一

日本物理学会 2008 年年次大会 24aTE-2　2008/03/24
Dynamic phase transition and spatial structures in a rotating field International-presentation

Naoya Fujiwara, Takeo Kobayahsi, Hirokazu Fujisaka

Statphys 23

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P157
Nonlinear Dynamics in a Periodically Driven Coupled Oscillator System International-presentation

Naoya Fujiwara

The Fourth International Seminar on Applied Analysis and Synthesis of Complex systems　2007/06/28
回転外力下でのパターンダイナミクス II

藤原直哉, 小林, 丈朗, 藤坂博一

日本物理学会 2007 年春季大会　2007/03/21

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21aPS-33
回転外力に駆動されるパターンの動力学

藤原直哉

生命リズムと振動子ネットワーク　2006/10/18

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ポスター講演22
回転外力下でのパターンダイナミクス

藤原直哉, 小林丈朗, 藤坂博一

日本物理学会 2006 年秋季大会　2006/09/23

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23aXG-3
Spatiotemporal chaos driven by a rotating external field International-presentation

Naoya Fujiwara, Takeo Kobayashi, Hirokazu Fujisaka

Quantum Mechanics and Chaos

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PS-B36
Pattern dynamics in a rotating field International-presentation

Naoya Fujiwara, Takeo Kobayashi, Hirokazu Fujisaka

Dynamics Days Asia-Pacific 4　2006/07/13

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PD-11
周期外力および静的外力下でのキンクダイナミクス

藤原直哉, 藤坂博一

日本物理学会 2006 年年次大会　2006/03/29

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29pRD-5
Spatiotemporal dynamics in a rotating external field International-presentation

Naoya Fujiwara, Takeo Kobayashi, Hirokazu Fujisaka

Frontiers in Dynamics: Physical and Biological Systems

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PS 40
非対称ポテンシャル下での動的相転移と磁壁動力学

藤原直哉, 筒, 広樹藤坂

第 55 回理論応用力学講演会　2006/01/26

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3A07
動的相転移とカオス応答

藤原直哉, 小林, 丈朗, 筒, 広樹, 藤坂博一

日本物理学会 2005 年秋季大会　2005/09/22

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22aPS-45
Dynamic phase transition of Heisenberg spin system under rotating magnetic field International-presentation

Naoya Fujiwara, Takeo Kobayashi, Hiroki Tutu, Hirokazu Fujisaka

XXV Dynamics Days Europe 2005　2005/07/25

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P 1.61
振動磁場下における Heisenberg 強磁性体の動的相転移 (2)

藤原直哉, 小林, 丈朗, 筒, 広樹, 藤坂博一

日本物理学会第 60 回年次大会　2005/03/27

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27aPS-28
振動磁場下における動的相転移と磁壁構造

藤原直哉

第 13 回『凝縮系物理(非平衡系の統計物理) シンポジウム』 (つくば冬の学校 2004)　2005/01/20
Magnetic walls associated with the dynamic phase transition in the anisotropic XY-spin system International-presentation

Naoya Fujiwara, Hiroki Tutu, Hirokazu Fujisaka

International Symposium on Oscillation, Chaos and Network Dynamics in Nonlinear Science　2004/11/25

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P1-12
振動磁場下におけるHeisenberg強磁性体の動的相転移

藤原直哉, 筒, 広樹, 藤坂博一

日本物理学会第 59 回秋季大会　2004/09/14

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14aTC-6
動的相転移におけるキンクダイナミクス

藤原直哉, 筒, 広樹, 藤坂博一

日本物理学会第 58 回秋季大会　2003/09/20

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20pWE-6
強振動磁場下のIsing-Bloch転移

藤原直哉, 筒, 広樹, 藤坂博一

日本物理学会第 58 回年次大会　2003/03/30

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30pWJ-13
動的相転移と秩序化過程：異方的XYスピンモデル

藤原直哉, 筒, 広樹, 藤坂博一

日本物理学会第 57 回秋季大会　2002/09/06

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6aTB-12
人流データ分析で捉える社会構造の変化

藤原直哉

第１３回総合科学を考えるセミナー「ウィズコロナ時代の社会と情報科学」　2021/12/04

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Research Projects 14

A selection of spatial scale of population statistics by non-Poission GPS poin ts

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Shiga University

2024/04/01 - 2027/03/31
Integrated Dynamics Monitoring and Application for Land and Maritime Transport through Observation Data Collaboration

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: The University of Tokyo

2024/04/01 - 2027/03/31
データ駆動アプローチによる都市変容機構の解明

藤原直哉

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2024/04/01 - 2027/03/31
原シルクロードの形成－中央アジア山岳地帯の初期開発史に関する総合研究－

久米正吾, 久保田慎二, 藤澤明, 宮田佳樹, 竹内望, 瀬川高弘, 覚張隆史, 佐藤丈寛, 新井才二, 早川裕弌, 山口雄治, 辰巳祐樹, 青木高明, 藤原直哉

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(A)

Institution: 金沢大学

2021/04/05 - 2026/03/31
産業連関分析とネットワーク科学の融合アプローチによる地域内経済循環構造の解明

藤嶋翔太, 藤原直哉, 青木高明, 平松燈

Offer Organization: 日本学術振興会

System: 科学研究費助成事業挑戦的研究(萌芽)

Category: 挑戦的研究(萌芽)

Institution: 一橋大学

2022/06/30 - 2025/03/31
Development of the analytical framework of human mobility networks

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2021/04/01 - 2024/03/31
Uncovering transmission of tuberculosis based on spatial molecular epidemiology with person flow data

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

2020/04/01 - 2023/03/31
機械学習を用いた概念合成アプローチによる新商品アイデア自動創出技術の高度化

須藤明人, 藤原直哉, 徳田慶太

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(C)

Institution: 静岡大学

2019/04/01 - 2022/03/31
Development of the analytical framework of spatio-temporal networks using large-scale human mobility data

Fujiwara Naoya

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2018/04/01 - 2022/03/31

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In this project, the research regarding human mobility and interregional interactions through human mobility has been conducted. Considering features of GPS data, cell-tower-based data, and questionnaire-based human mobility data, studies on such as delineation based on the human mobility network analysis have been conducted. This framework has been applied to e.g. analyses of change of mobility after the COVID-19 pandemic, and the correlation between human mobility and spread of COVID-19 has been investigated. Mathematical models on spatial spread of infectious diseases and formation of cities have been introduced and studied, which fascilitates the understanding of the human mobility.
リアルタイム群集流動制御に関する基盤技術の研究開発

巳波弘佳, 藤原明広, 内田真人, 藤原直哉

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 関西学院大学

2017/04/01 - 2021/03/31

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大規模災害時の避難誘導のみならず，平常時における群集事故の回避や混雑解消のためにも，群集誘導の必要性が高まっている．そこで本研究では，リアルタイム群集流動制御技術の確立を目的として，群集流動制御の数理モデルの構築，制御アルゴリズムの設計を行い，実データに基づく大規模シミュレーションによる有効性評価を目標としている．これまでに主に以下の成果を得た．・人間を含む生物のモビリティとその数理モデルに関して，ミクロ的には各要素の持つ値が変化しているにも関わらず，マクロ的な視点ではスケールフリー性が維持されるメカニズムを調べた．再現できるモデルを検討し，数値実験によりその妥当性を評価した．・群集流動制御に適したネットワーク設計に関する研究成果として，主にリンク・ノード保護による高信頼化設計法に関する研究を行った．これは，一部のリンク・ノードを保護することによって，ネットワーク全体の信頼性を向上させることを目的とした設計問題である．これに対して，必要な信頼性を有するネットワークを設計するためにリンク付加のみ，もしくはリンク保護のみで行うよりも，リンク付加と保護を両方適切に組み合わせることによってコストを抑えられる可能性がある．そこで本稿では，リンク付加と保護を組み合わせたネットワーク設計問題を定式化し，NP困難性を示し，条件を限定した場合に多項式時間で解けることを示した．さらに，実際のネットワークトポロジに対してアルゴリズムを適用することにより，リンク付加と保護を組み合わせたネットワーク設計の有効性を示した．
Tracing of transmission routes of tuberculosis using geographical information of patients and genetic analysis of clinical isolates

WADA Takayuki

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Nagasaki University

2017/04/01 - 2020/03/31

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In order to investigate the transmission of tuberculosis infection, molecular epidemiology, in which genes of clinical strains isolated from patients are compared, is widely used. In this study, we visualized the correlation between spread of pathogens estimated from genetic analysis of the strain and spatial diffusion estimated from the spatial relationship (distance between residences) of the patients. Moreover, from people-flow data based on person-trip survey, we estimated, visualized, and compared how people are in contact with other people resident in surrounding areas. As a result, strong geographic anisotropy was monitored in the amount of contact of people that can be the background of epidemic of infection in a society.
Analysis of epidemic spreading and infection control with complex network theory

Fujiwara Naoya

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Young Scientists (B)

2015/04/01 - 2019/03/31

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In this research, we employed human mobility data in urban areas to construct time-dependent contact networks, performed simulations of spread of an infectious disease on the contact networks, and derived an approximated equation to estimate the final size of the infection. By varying a control parameter for the contact network, we found that the system shows the percolation transition and the scaling behavior. In the approximation, we can use small numbers of eigenvalues and eigenvectors of the contact networks, and found that the numerical solution of this equation well describes the simulation results with respect to the final size. Therefore,the relevant features of the spreading pattern can be captured by the eigenvectors of the connectivity matrices of the contact networks.
Understanding human proximity patterns by big data analysis and its application to proximity-based services

Fujihara Akihiro, MIWA HIROYOSHI, FUJIWARA NAOYA

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Young Scientists (B)

Institution: Fukui University of Technology

2015/04/01 - 2017/03/31

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Statistical properties of human proximity patterns have been analyzed using big data of human mobility patterns. Through visualizing these patterns in Japanese metropolitan areas, their spatial patterns have been investigated. Numerical simulations of epidemic routing, which is a routing method in delay tolerant networking have also been performed. In general, the temporal change of information spreading size obeys a logistic curve. By changing the communication distance, the inflection point of the curve is focused. As a result, a universal relation between the number of mobile nodes and the communication distance is found. Furthermore, methods for creating people flow data have been compared through the impacts on the performance of epidemic routing. A possibility of overestimating the performance by illusory and excessive aggregation of representative points is confirmed. These results are considered to be useful for evaluating proximity-based services.
Complex network analysis of transport phenomena in fluids

FUJIWARA Naoya

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Research Activity Start-up

Institution: The University of Tokyo

2012/08/31 - 2014/03/31

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The purpose of this research is to analyze the transport phenomena in fluids using methodologies of the complex network science. We have shown properties of the transport phenomena which has not been clarified with the conventional methods. First, we constructed the network of a turbulence model and analyzed the network using the betweenness centrality. We found that the boundary region between convection rolls show high betweenness centrality. Next, we considered the change of the steady state under the change of the control parameters of the system. We have classified the problem into three sub classes. We took into account the conditions specific to each situation, derived the perturbation equation, and showed that the derived equation is exact in the case that the number of particles is conserved.

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Social Activities 2

RIMS共同研究「人口と環境の数理地理モデリング」

2021/06/24 - 2021/06/25
第 34 回応用地域学会（ARSC）研究発表大会プログラム委員会委員

2020/11/28 - 2020/11/29