Updated on 2022/08/11

写真a

 
TOYOIZUMI, Hiroshi
 
Affiliation
Faculty of Commerce, Graduate School of Accountancy
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   School of Fundamental Science and Engineering

  • Faculty of Science and Engineering   Graduate School of Fundamental Science and Engineering

Research Institute

  • 2005
    -
     

    産業経営研究所   兼任研究所員

Education

  •  
    -
    1998

    Waseda University   Graduate School, Division of Science and Engineering  

Degree

  • Waseda University   Ph.D. of Engineering in Mathematical Physics,

Professional Memberships

  •  
     
     

    Operations Research Society of Japan

  •  
     
     

    IEICE

  •  
     
     

    日本応用数理学会

  •  
     
     

    IEEE

  •  
     
     

    INFORMS

  •  
     
     

    SIAM

▼display all

 

Research Areas

  • Social systems engineering

  • Safety engineering

Research Interests

  • Applied Probability

Papers

  • Reduction of Foraging Work and Cooperative Breeding

    Hiroshi Toyoizumi, Jeremy Field

    ACTA BIOTHEORETICA   62 ( 2 ) 123 - 132  2014.06  [Refereed]

     View Summary

    Using simple stochastic models, we discuss how cooperative breeders, especially wasps and bees, can improve their productivity by reducing foraging work. In a harsh environment, where foraging is the main cause of mortality, such breeders achieve greater productivity by reducing their foraging effort below full capacity, and they may thrive by adopting cooperative breeding. This could prevent the population extinction of cooperative breeders under conditions where a population of lone breeders cannot be maintained.

    DOI PubMed

  • Dynamics of social queues

    Hiroshi Toyoizumi, Jeremy Field

    JOURNAL OF THEORETICAL BIOLOGY   346   16 - 22  2014.04  [Refereed]

     View Summary

    Queues formed by social wasps to inherit the dominant position in the nest are analyzed by using a transient quasi-birth-and-death (QBD) process. We show that the extended nest lifespan due to division of labor between queen and helpers has a big impact on nest productivity. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

    DOI PubMed

  • Direct and Indirect Control of the Initiation of Meiotic Recombination by DNA Damage Checkpoint Mechanisms in Budding Yeast

    Bilge Argunhan, Sarah Farmer, Wing-Kit Leung, Yaroslav Terentyev, Neil Humphryes, Tomomi Tsubouchi, Hiroshi Toyoizumi, Hideo Tsubouchi

    PLOS ONE   8 ( 6 ) e65875  2013.06  [Refereed]

     View Summary

    Meiotic recombination plays an essential role in the proper segregation of chromosomes at meiosis I in many sexually reproducing organisms. Meiotic recombination is initiated by the scheduled formation of genome-wide DNA double-strand breaks (DSBs). The timing of DSB formation is strictly controlled because unscheduled DSB formation is detrimental to genome integrity. Here, we investigated the role of DNA damage checkpoint mechanisms in the control of meiotic DSB formation using budding yeast. By using recombination defective mutants in which meiotic DSBs are not repaired, the effect of DNA damage checkpoint mutations on DSB formation was evaluated. The Tel1 (ATM) pathway mainly responds to unresected DSB ends, thus the sae2 mutant background in which DSB ends remain intact was employed. On the other hand, the Mec1 (ATR) pathway is primarily used when DSB ends are resected, thus the rad51 dmc1 double mutant background was employed in which highly resected DSBs accumulate. In order to separate the effect caused by unscheduled cell cycle progression, which is often associated with DNA damage checkpoint defects, we also employed the ndt80 mutation which permanently arrests the meiotic cell cycle at prophase I. In the absence of Tel1, DSB formation was reduced in larger chromosomes (IV, VII, II and XI) whereas no significant reduction was found in smaller chromosomes (III and VI). On the other hand, the absence of Rad17 (a critical component of the ATR pathway) lead to an increase in DSB formation (chromosomes VII and II were tested). We propose that, within prophase I, the Tel1 pathway facilitates DSB formation, especially in bigger chromosomes, while the Mec1 pathway negatively regulates DSB formation. We also identified prophase I exit, which is under the control of the DNA damage checkpoint machinery, to be a critical event associated with down-regulating meiotic DSB formation.

    DOI PubMed

  • Analyzing Meiotic DSB Interference by Combining Southern Blotting and Microarray Analysis

    H. Toyoizumi, H. Tsubouchi

    The Fifth International Conference on Bioinformatics, Biocomputational Systems and Biotechnologies (Biotechno 2013)    2013

  • Estimating the Number of Double-Strand Breaks Formed During Meiosis from Partial Observation

    Hiroshi Toyoizumi, Hideo Tsubouchi

    JOURNAL OF COMPUTATIONAL BIOLOGY   19 ( 12 ) 1277 - 1283  2012.12  [Refereed]

     View Summary

    Analyzing the basic mechanism of DNA double-strand breaks (DSB) formation during meiosis is important for understanding sexual reproduction and genetic diversity. The location and amount of meiotic DSBs can be examined by using a common molecular biological technique called Southern blotting, but only a subset of the total DSBs can be observed; only DSB fragments still carrying the region recognized by a Southern blot probe are detected. With the assumption that DSB formation follows a nonhomogeneous Poisson process, we propose two estimators of the total number of DSBs on a chromosome: (1) an estimator based on the Nelson-Aalen estimator, and (2) an estimator based on a record value process. Further, we compared their asymptotic accuracy.

    DOI PubMed

  • Reverse preferential spread in complex networks

    H. Toyoizumi, S. Tani, N. Miyoshi, Y. Okamoto

    Phys. Rev. E   86:021103 ( 2 Pt 1 ) 021103  2012.08  [Refereed]

     View Summary

    Toyoizumi, H, Tani, S, Miyoshi, N & Okamoto, Y, 2012, 'Reverse preferential spread in complex networks', <i>Physical Review E</i>, vol. 86, no. 2.

    DOI PubMed

  • Budding Yeast Pch2, a Widely Conserved Meiotic Protein, Is Involved in the Initiation of Meiotic Recombination

    Sarah Farmer, Eun-Jin Erica Hong, Wing-Kit Leung, Bilge Argunhan, Yaroslav Terentyev, Neil Humphryes, Hiroshi Toyoizumi, Hideo Tsubouchi

    PLOS ONE   7 ( 6 ) e39724  2012.06  [Refereed]

     View Summary

    Budding yeast Pch2 protein is a widely conserved meiosis-specific protein whose role is implicated in the control of formation and displacement of meiotic crossover events. In contrast to previous studies where the function of Pch2 was implicated in the steps after meiotic double-strand breaks (DSBs) are formed, we present evidence that Pch2 is involved in meiotic DSB formation, the initiation step of meiotic recombination. The reduction of DSB formation caused by the pch2 mutation is most prominent in the sae2 mutant background, whereas the impact remains mild in the rad51 dmc1 double mutant background. The DSB reduction is further pronounced when pch2 is combined with a hypomorphic allele of SPO11. Interestingly, the level of DSB reduction is highly variable between chromosomes, with minimal impact on small chromosomes VI and III. We propose a model in which Pch2 ensures efficient formation of meiotic DSBs which is necessary for igniting the subsequent meiotic checkpoint responses that lead to proper differentiation of meiotic recombinants.

    DOI PubMed

  • Analysis of the dynamics of social queues by quasi-birth-and-death processes (abstract only).

    Hiroshi Toyoizumi, Jeremy Field

    SIGMETRICS Performance Evaluation Review   39 ( 4 ) 29 - 30  2012.04  [Refereed]

     View Summary

    Toyoizumi, H & Field, J, 2012, 'Analysis of the dynamics of social queues by quasi-birth-and-death processes (abstract only)', <i>ACM SIGMETRICS Performance Evaluation Review</i>, vol. 39, no. 4, p. 29.

  • Analysis of the dynamics of social queues by quasi-birth-and-death processes

    H. Toyoizumi, J. Field

    SIGMETRICS Perform. Eval. Rev.   39 ( 4 ) 29 - 30  2012

  • The dynamics of social queues

    H. Toyoizumi, J. Field

    8th European Conference on Mathematical and Theoretical Biology, and Annual Meeting of The Society for Mathematical Biology (ECMBT 2011)    2011

  • Analysis of the Dynamics of Social Queues by Quasi-Birth-and-Death Processes

    H. Toyoizumi, J. Field

    The Seventh International Conference on Matrix-Analytic Methods in Stochastic Models (MAM7)    2011

  • Sample path analysis of contribution and reward in cooperative groups

    Hiroshi Toyoizumi

    JOURNAL OF THEORETICAL BIOLOGY   256 ( 3 ) 311 - 314  2009.02  [Refereed]

     View Summary

    Explaining cooperative behavior is one of the major challenges in both biology and human society. The individual reward in cooperative group depends on how we share the rewards in the group. Thus, the group size dynamics in a cooperative group and reward-a I location rule seem essential to evaluate the emergence of cooperative groups. We apply a sample path-based analysis called an extension of Little's formula to general cooperative group. We show that the expected reward is insensitive to the specific reward-allocation rule and probabilistic structure of group dynamics, and the simple productivity condition guarantees the expected reward to be larger than the average contribution. As an example, we take social queues to see the insensitivity result in detail. (c) 2008 Elsevier Ltd. All rights reserved.

    DOI PubMed

  • Analytical model of on-demand streaming services based on renewal reward theory

    Hiroshi Toyoizumi

    Advances in Queueing Theory and Network Applications     35 - 45  2009  [Refereed]

     View Summary

    We propose an analytical model based on renewal reward theory to investigate the dynamics of an on-demand streaming service. At the same time, we also propose a simple method combining a method of multicasts and method of unicasts that can reduce the download rate from the streaming server without causing delay. By modeling the requests as a Poisson arrival and using renewal reward theory, we study the dynamics of this streaming service and derive the optimal combination of unicast and multicast methods. We even show how to estimate the fluctuation of download rates of a streaming service. © Springer Science+Business Media LLC 2009.

    DOI

  • スズメバチの作る待ち行列

    豊泉 洋

    2006年度待ち行列シンポジウム「ユビキタスネットワーク社会における情報通信サービスの設計・評価法」    2007

  • コンピュータウィルスの生態学

    豊泉 洋

    オペレーションズリサーチ   52 ( 7 ) 403 - 408  2007

  • An infinite phase-size BMAP/M/1 queue and its application to secure group communication

    Hiroshi Toyoizumi

    SECRYPT 2006: Proceedings of the International Conference on Security and Cryptography     283 - 288  2006  [Refereed]

     View Summary

    We derive the bounds of the mean queue length of an infinite phase size BMAP/M/1 queue which has an M/M/infinity-type phase transition, and use them to evaluate the performance of secure group communication. Secure communication inside a groups on an open network is critical to enhance the internet capability. Extending the usual matrix analysis to the operator analysis, we derive a new estimation of the degradation of secure group communication model.

  • Observation of Spread Dynamics of Malicious Software and its Comparison to Theoretical Model

    Tatehiro Kaiwa, Hiroshi Toyoizumi

    Symposium of Network Ecology    2006

  • An Infinite Phase-size BMAP/M/1 Queue and Its Application to Secure Communication

    Hiroshi Toyoizumi

    13th INFORMS Applied Probability Conference    2006

  • Evaluation method of download rate distribution in the multicast streaming

    Hiroshi Toyoizumi

    The 2005 Spring National Conference of ORSJ    2005

  • tochastic Features of Computer Viruses: Towards Theoretical Analysis and Simulation

    Hiroshi Toyoizumi, Yuuzo Kobayashi, Kenta Kaiwa, Jiyun Shitozawa

    Proceedings of the 5th St.Petersburg Workshop on Simulation    2005

  • Obeservation and Modeling Method of Dynamics of Computer Virus Spread

    Hiroshi Toyoizumi, Kenta Kaiwa

    IEICE 3rd QoS Workshop    2005

  • Performance evaluation of secure group communication

    H Toyoizumi, M Takaya

    JOURNAL OF THE OPERATIONS RESEARCH SOCIETY OF JAPAN   47 ( 1 ) 38 - 50  2004.03

     View Summary

    There are demands for secure group communication on the internet, such as pay-per-view type broadcasting, business confidential information sharing and teleconference. Secure communication inside a groups on an open network is critical to enhance the internet capability. The public key system is not sufficient to support the group security, since it is not scalable for large groups. Some researchers propose a scalable group security model, managing several common keys for encryption and decryption sharing inside the community. In this paper, we will evaluate the performance of these group security model. Using M/G/infinity queueing models and the basic queueing theory, we show how to find the optimal condition of the allocation of the common keys if the joins to group is a Poisson process. In addition, we show our optimal condition may work for more general arrival processes by using the cross covariance formula (a variant of Papangelou's formula) for the stochastic intensity of departure process.

    DOI

  • Queues in genome

    Hiroshi Toyoizumi

    Communications of Operations Research of Japan   47 ( 7 ) 413 - 417  2004

  • Detect the Source of Worms with Spoofed Email Address

    Hiroshi Toyoizumi

    Technical Report of IPSJ   004-EVA-9 ( 62 ) 33 - 36  2004

  • Performance Evaluation of Defense Strategies against Computer Virus

    H. Toyoizumi

    Seventh INFORMS TELECOM     131 - 133  2003

  • Predators

    Toyoizumi H, Serban C, Marceau C, Foley S, Kara A

    Proceedings of the 2002 workshop on New security paradigms - NSPW '02    2002  [Refereed]

     View Summary

    Toyoizumi, H, Serban, C, Marceau, C, Foley, S & Kara, A, 2002, 'Predators', <i>Proceedings of the 2002 workshop on New security paradigms - NSPW '02</i>, ACM Press, New York, New York, USA, p. 11.

  • Predators: good will mobile codes combat against computer viruses.

    Hiroshi Toyoizumi, Atsuhi Kara

    Proceedings of the 2002 Workshop on New Security Paradigms, Virginia Beach, VA, USA, September 23-26, 2002     11 - 17  2002  [Refereed]

  • Predators: good will codes combat against computer viruses

    H. Toyoizumi, A. Kara

    ACM SIGSAC New Security Paradigms Workshop 2002    2002

  • Two Extremal Autocorrelated Arrival Processes

    Toyoizumi H, Shanthikumar J, Wolff R

    Probability in the Engineering and Informational Sciences   7 ( 04 )  1997.10  [Refereed]

     View Summary

    Toyoizumi, H, Shanthikumar, J & Wolff, R, 1997, 'Two Extremal Autocorrelated Arrival Processes', <i>Probability in the Engineering and Informational Sciences</i>, vol. 7, no. 04, p. 343.

  • Sengupta's Invariant Relationship and Its Application to Waiting Time Inference

    H. Toyoizumi

    Journal of Applied Probability   34 ( 34 ) 795 - 799  1997.09  [Refereed]

     View Summary

    Toyoizumi, H, 1997, 'Sengupta's Invariant Relationship and Its Application to Waiting Time Inference', <i>Journal of Applied Probability</i>, vol. 34, no. 3, p. 795.

  • Distribution Measurement of Delay by Sengupta's Invariant Relationship

    H. Toyoizumi

    ITC Specialist Seminar    1995

  • A SIMPLE METHOD OF ESTIMATING MEAN DELAY BY COUNTING ARRIVALS AND DEPARTURES

    H TOYOIZUMI

    IEEE INFOCOM 93 : THE CONFERENCE ON COMPUTER COMMUNICATIONS, PROCEEDINGS, VOLS 1-3     829 - 834  1993  [Refereed]

    DOI

  • EVALUATING MEAN SOJOURN TIME ESTIMATES FOR THE M/M/1 QUEUE

    H TOYOIZUMI

    COMPUTERS & MATHEMATICS WITH APPLICATIONS   24 ( 1-2 ) 7 - 15  1992.07  [Refereed]

     View Summary

    Mean sojourn time is one of the most important performance measures for queueing systems. It is difficult to obtain the real sojourn time of a customer directly, so it is also difficult to estimate the mean sojourn time. In this paper, we propose a new and relatively simple estimate of the mean sojourn time in a single server queue, using the number of arrivals and the number of departures. This method can be used for evaluating the quality and the performance of call processing in communication switching systems, for example. We evaluate the accuracy of this estimate for an M/M/1 queue, using some results obtained by Jenkins. This estimate is compared with two other standard estimates of the mean sojourn time obtained from the sequence of actual arrival and departure times.

  • Continuous Dependence on Obstacles in Variational Inequalities

    H. Toyoizumi

    Functional Equations   34 ( 1 ) 103 - 115  1991

  • Optimal Merging and Its Evaluation in Multicast

    Hiroshi Toyoizum

    INFORMS Hong Kong  

  • 相関を比較する確率順序

    豊泉 洋

    オペレーションズリサーチ   52 ( 9 ) 577 - 579

▼display all

Books and Other Publications

Misc

  • 変動の激しい到着過程をもつ無限サーバー待ち行列

    豊泉洋

    日本オペレーションズ・リサーチ学会秋季研究発表会アブストラクト集   2018   68‐69  2018.09

    J-GLOBAL

  • ブロックチェーン技術を利用した配車サービスモデルの提案と評価

    加藤浩介, 豊泉洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2018   94‐95  2018.03

    J-GLOBAL

  • 財務諸表による租税回避判定

    松岡隼歩, 佐藤賢, 豊泉洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2018   76‐77  2018.03

    J-GLOBAL

  • The Growth of Non-Giant Component in Preferentially-Attached Networks

    下邨貴裕, 豊泉洋

    電子情報通信学会技術研究報告   117 ( 474(COMP2017 45-53) ) 9‐16  2018.02

    J-GLOBAL

  • 株取引板の優先権付き待ち行列モデル

    豊泉洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2017   49‐50  2017.03

    J-GLOBAL

  • Pull型情報拡散モデルにおける最適な情報伝播方法

    皆川拓, 豊泉洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2017   55‐56  2017.03

    J-GLOBAL

  • Swarm behavior of traders with different subjective predictions in the Market

    Hiroshi Toyoizumi

       2017.03

    Internal/External technical report, pre-print, etc.  

     View Summary

    A combination of a priority queueing model and mean field theory shows the<br />
    emergence of traders&#039; swarm behavior, even when each has a subjective<br />
    prediction of the market driven by a limit order book. Using a nonlinear Markov<br />
    model, we analyze the dynamics of traders who select a favorable order price<br />
    taking into account the waiting cost incurred by others. We find swarm behavior<br />
    emerges because of the delay in trader reactions to the market, and the<br />
    direction of the swarm is decided by the current market position and the<br />
    intensity of zero-intelligent random behavior, rather than subjective trader<br />
    predictions.

  • Preferential Attachmentで生成されるネットワークの分裂構造

    下邨貴裕, 豊泉洋

    ネットワーク生態学シンポジウム予稿集(CD-ROM)   14th   ROMBUNNO.SHIMOMURA  2017

    J-GLOBAL

  • メロン栽培における最適摘心戦略

    兒玉恭輔, 佐藤真史, 豊泉洋

    日本オペレーションズ・リサーチ学会秋季研究発表会アブストラクト集   2016   216‐217  2016.09

    J-GLOBAL

  • 在庫管理最適化を目指した公平なコスト配分法

    伊藤敬宏, 豊泉洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2016   27‐28  2016.03

    J-GLOBAL

  • 伝搬速度限定モデルの情報伝搬シミュレーションと考察

    皆川拓, 谷聖一, 豊泉洋

    ネットワーク生態学シンポジウム予稿集(CD-ROM)   13th   ROMBUNNO.POSUTA5  2016

    J-GLOBAL

  • Spread of Information over Social Network and Its Advertisement Effect

    TOYOIZUMI Hiroshi, NAKAGAWA Shingo

    IEICE technical report   114 ( 6 ) 119 - 123  2014.04

     View Summary

    Various information is distributed on social networks. Especially, companies are increasing their marketing activities on social network. There are two main categories of marketing on social network: (1) advertisement by word of mouth such as &quot;like&quot; and &quot;share&quot;, and (2) direct marketing such as banners displayed on the customers&#039; window. In this research we will model the spread process of word of mouth advertisement on social network, and compare their effectiveness with direct marketing.

    CiNii

  • フィールド情報学入門-自然観察,社会参加,イノベーションのための情報学-, 京都大学フィールド情報学研究会(編), 共立出版, 2009-03, B5判, 定価(本体3,200円+税)

    豊泉 洋

    電子情報通信学会誌   92 ( 12 )  2009.12

    CiNii

  • Markovian Arrival Process と暗号通信

    豊泉 洋

    オペレーションズ・リサーチ : 経営の科学 = [O]perations research as a management science [r]esearch   53 ( 6 ) 340 - 345  2008.06

     View Summary

    M/M/∞待ち行列のダイナミックスに従う位相変化を待つBMAP/M/1待ち行列の待ち時間を解析し,グループでの暗号通信のセキュリティを評価する.M/M/1待ち行列,MAP/M/1待ち行列との対比を行いながら,BMAP/M/1待ち行列の系内客数の上下限を,通常用いられる行列の反復計算を用いずに求める方法を示す.

    CiNii

  • 「情報」を学び直す, 石井健一郎(著), "「情報」を学び直す", NTT出版(2007-04), B6版, 定価(本体1,600円+税)

    豊泉 洋

    電子情報通信学会誌   90 ( 10 )  2007.10

    CiNii

  • 統計数理は隠された未来をあらわにする ベイジアンモデリングによる現実世界イノベーション, 樋口知之(監修・著), 石井信,照井伸彦,井元清哉,北川源四郎(著), "「統計数理は隠された未来をあらわにする ベイジアンモデリングによる現実世界イノベーション", 東京電機大学出版局(2007-06), A5版, 定価(本体2,200円+税)

    豊泉 洋

    電子情報通信学会誌   90 ( 10 )  2007.10

    CiNii

  • ネットワークのセキュリティ評価と新しい確率モデル : コンピュータウィルスの生態学(信頼性-温故知新-)

    豊泉 洋

    シンポジウム   ( 57 ) 53 - 70  2007.03

     View Summary

    コンピュータウィルスのモデリング手法に対する解説と評価を行なう。疫学的モデルから、Lotka-Volterra方程式、出生死滅過程、確率微分方程式、さらには、スケールフリーネットワーク上でのpercolationモデルなどの最新の確率的モデリング手法を、実際のコンピュータウィルスを紹介しながら解説し、コンピュータウィルスの数理的な生態モデルがネットワークセキュリティ上、重要であることを示す。

    CiNii

  • B-7-3 Worm-type Attack Packet Source Identification System : Attack Packet Arrival-Interval Analysis Approach

    池川 隆司, 豊泉 洋

    Proceedings of the Society Conference of IEICE   2005 ( 2 )  2005.09

    CiNii

  • マルチキャストストリーミングにおけるダウンロードレート分布の評価法(待ち行列モデルとその周辺(2))

    豊泉 洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2005   52 - 53  2005.03

    CiNii

  • ゲノムの中にあらわれた待ち行列

    豊泉 洋

    オペレーションズ・リサーチ : 経営の科学 = [O]perations research as a management science [r]esearch   49 ( 7 ) 413 - 417  2004.07

     View Summary

    バイオインフォマテックスを初めて学んだ待ち行列研究者の苦闘とゲノム情報の解析に待ち行列を使った遺伝子解析を解説する.

    CiNii

  • Optimal Merging Scheme of Multicast Streaming

    TOYOIZUMI Hiroshi, TANAKA Hiroyuki

    IEICE technical report   104 ( 18 ) 33 - 36  2004.04

     View Summary

    Combining multicast and unicast, we show the download rate from the streaming server can be effectively reduced. By modeling the request from users as a Poisson arrival, we can derive the optimal combination of unicast and multicast. Even in the large-scale streaming service, the download rate will be reduced by the order of n1/2, where n is the number of users in the streaming service.

    CiNii

  • グループセキュリティサービスにおける暗号鍵管理サーバの性能評価(待ち行列(2))

    高谷 松慶, 豊泉 洋

    日本オペレーションズ・リサーチ学会春季研究発表会アブストラクト集   2003   162 - 163  2003.03

    CiNii

  • Deterministic Analysis of Fluid Input Queues Using Inverse Representations

    TOYOIZUMI Hiroshi

    IEICE technical report. Information networks   102 ( 131 ) 1 - 6  2002.06

     View Summary

    We propose a new concept of performance evaluation based on deterministic analysis using inverse functions of the input and output of systems. Traffic theory and queueing theory depend heavily on the probabilistic behavior of systems and users. In general, only the probabilistic features of delay and loss can be obtained by probalisctic arguements. Now many new application, especially streaming servises such as VoIP and Broadcasting over internet, requires a deterministic guarantee of their performance. Hence, many researches start to focus on deterministic analysis such (σ,ρ)-calculus, where inputs to systems are described by some deterministic manners. In this paper, we use inverse functions of input and output of systems to evaluate its performance. Especially, we apply these concept to the case of multi-inputs sharing an FIFO queue, and evaluate the delay of each input.

    CiNii

  • グループセキュリティ通信の性能評価(インターネットへの待ち行列理論の応用)

    豊泉 洋, 高谷 松慶

    シンポジウム   ( 45 ) 29 - 37  2001.04

     View Summary

    インターネット上の各種コミュニティーにおけるグループ内の通信やマルチキャストによる有料番組の提供や企業内の重要な情報の共有サービスなど、オープンなネットワーク上で、セキュリティを確保しながら多数の人が情報を共有する必要性が高まっている。その一つの実現方法としてグループ内で共通の鍵を複数使って暗号通信を行うグループセキュリティ通信という方法が提案されている。ここでは、待ち行列の基本的な考え方を応用することにより、グループセキュリティ通信を行う場合の効率的な鍵の配置方法を導出する。

    CiNii

  • MODELING AND EVALUATION OF INTEGRATED SERVICE TRAFFIC

    TOYOIZUMI Hiroshi

    IEICE technical report. Information networks   100 ( 105 ) 33 - 40  2000.06

     View Summary

    We propose a method for modeling auto-correlated traffic sent by sources in integrated service networks. We define local and global descriptors of the source traffic, and using block renewal processes, we obtain the Laplace-Stieltjes transform (LST) of the workload in the queue and the effective bandwidth for aggregated traffic. We also discuss how the change of the descriptors affects the mean workload in the queue and the effective bandwidth.

    CiNii

  • Charging Based on Queue Observation

    豊泉 洋

    日本オペレーションズ・リサーチ学会秋季研究発表会アブストラクト集   1999   254 - 255  1999.09

    CiNii

  • A Study of VP bandwidth adjustment method based on Self-sizing control on ATM-CL network

    TANIKAWA Masaki, TOYOIZUMI Hiroshi, KONDO Takashi, TSUCHIYA Toshiaki

    IEICE technical report. Communication systems   98 ( 301 ) 13 - 18  1998.09

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    The exponential growth of the Internet traffic causes the various bottleneck problems in the backbone networks. This affects the degradation of service quality and unstable operation of routing management. Therefore, authors have proposed the CL-Core Network Architecture as a large-scale ATM based connectionless network architecture. An application of the Self-sizing control technology may be more effective in the provision of a cost-effective and high quality connectionless network. This paper proposes a new VP bandwidth adjustment method based on Self-sizing control (called a queue length snapshot method). The theoretical and simulation study shows the proposed method could make an appropriate bandwidth estimate in spite of quite a long observation period.

    CiNii

  • セルフサイジングによるVPC容量の設計法

    横井 弘文, 豊泉 洋, 斎藤 洋

    NTT R & D   45 ( 12 ) 1323 - 1332  1996.12

    CiNii

  • New Auto-correlated Traffic Process

    Shanthikumar G.J, Wolff W.R

    Proceedings of the Society Conference of IEICE   1996 ( 2 )  1996.09

     View Summary

    マルチメディア通信網において、ますます多様化するトラヒック扱うためには、自己相関のあるトラヒックをモデル化することが非常に重要である。ここでは、自己相関のあるトラヒックを測定データから簡易に構成できる新たなトラヒックモデルを提案する。

    CiNii

  • Virtual Path Bandwidth Control Algorithm in the Self-sizing Network Operation Systems

    TSUCHIYA Toshiaki, TOYOIZUMI Hiroshi

    Proceedings of the IEICE General Conference    1995

     View Summary

    ATM網は多種多様なサービスを扱うことを期待されている.その対象は既存のサービスだけでなく、将来実現するであろうサービスも含み、それらを統合的に扱うためには、需要予測→網設計→網品質管理というサイクルによる、単一サービスを対象とした将来のトラヒックオペレーションでは対処しきれない.そこでATM網におけるVirtual Path(VP)設定容量の可変性を利用して、変動する需要に対して網形態を適合させていくVP容量制御に関する検討が行われている.このVP容量制御の概念を含むトラヒックオペレーション全般によって実現されるSelf-sizing networkの検討が現在進められている.本稿では特にSelf-sizing network内におけるVP容量制御のアルゴリズム部分の実現方法に関して報告する.

    CiNii

  • Consideration on Traffic Flow Information Model

    Amada Hiroyuki, Suzuki Gengo, Nogami Shinya, Toyoizumi Hiroshi

    Technical report of IEICE. SSE   93 ( 256 ) 83 - 88  1993.09

     View Summary

    Traffic flow information is indispensable to manage a circuit switched network.It ranges from traffic measurements to its highly processed information.Information identifying traffic values such as traffic load and calls is complex to define it.To cause the information to smoothly flow,it is required to be standardized. This paper describes classification of traffic infomation and a traffic information model.Top-down and bottom-up approaches are applied to the modelling of the information.It also discusses that the above information be modelled by three elements:network component,time,and call characteristic.

    CiNii

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Awards

  • Biothechno 2013 Best Paper Award

    2013.05  

  • IEICE Switching Workshop SSE Research Award

    1999.03  

  • IEICE Young Research Engineer Award

    1997.03  

Research Projects

  • コンピュータウィルスの確率論的モデル化とその能動的撃退手法の性能評価の研究

    科学研究費助成事業(会津大学)  科学研究費助成事業(萌芽研究)

  • 決定論型と確率論型モデリングの融合による新しい待ち行列評価モデルの研究

    科学研究費助成事業(会津大学)  科学研究費助成事業(奨励研究(A))

Specific Research

  • 集団と個体のインタラクションのある場合の意思決定理論とその実験的検証

    2019  

     View Summary

    本研究は、個体と集団のインタラクションのあるプロセスにおける個体の意思決定問題の解析手法として新たに提案・研究されている平均場ゲームや非線形マル コフ過程を用いた解析手法を、ネットワーク上での情報拡散、生物の集団行動、株取引の3つ実例に応用できるように改良し、実際のソーシャルメディアのデー タ、株式市場の高速取引データ、ハチなどの生物の観測データを用いて、その妥当性・応用可能性について実験・検証・改良を行った。

  • 待ち行列モデルのグループダイナミックス評価への応用とその検証実験

    2015  

     View Summary

    待ち行列理論やネットワーク理論を使って、自然界で実際に見られる生物の相互の関係、特に、階級構造(女王、働き蜂)などのグループダイナミックスをモデル化し、グループ全体の性能を分析する手法を考案する。さらに、階級構造や相互関係などの待ち行列の操作実験を行うことで、分析結果を実証し、グループにおける協力関係などのダイナミックスを解明する新しい手法を開発することを目的とする。また、これらの新しいグループ全体の性能評価手法を生物だけではなく、人間社会の組織等への応用も視野に含める。

  • 二重鎖切断の不完全情報から遺伝子混合の特性を推定する数学手法の研究

    2014  

     View Summary

    It is well-known that crossover formation events on a chromosome interfere with each other during meiosis, and this interference affects the distribution of genetic exchanges on a chromosome in sexual reproduction. However, due to the technical difficulties, it is unknown if meiotic double strand break (DSB) formation, the initiating event of meiotic recombination, shows interference. We discuss a method that employs probability theory of survival analysis in conjunction with: chromosome fragment distribution, detected by Southern blotting; and genome-wide DSB intensity maps, obtained by microarray analysis. We show that this method is a promising tool to analyse DSB interference.

  • 待ち行列モデルの生物グループダイナミックスへの応用とその検証実験

    2014   Jeremy Field

     View Summary

    Using simple stochastic models, we discuss how cooperative breed- ers, especially wasps and bees, can improve their productivity by reducing foraging work. In a harsh environment, where foraging is the main cause of mortality, such breeders achieve greater productivity by reducing their for- aging effort below full capacity, and they may thrive by adopting cooperative breeding. This could prevent the population extinction of cooperative breeders under conditions where a population of lone breeders cannot be maintained.&nbsp;

  • 待ち行列理論による社会性動物の協調行動の分析

    2011  

     View Summary

    本研究では、自然界で実際に見られる協力関係のグループダイナミックスを一つのシステムとし てモデル化し、そのシステムに対して待ち行列理論を用いることにより、グループ全体の性能を分析した。特に、マレーシアに見られるhover waspが女王の座を巡って作る待ち行列に関する実際のデータを解析し、Markov chain によりモデル化し、その特性を分析した。A wide variety of animals are known to form simple hierarchical groups called social queues, where individuals inherit resources or social status in a predictable order. Queues are often age-based, so that a new individual joins the end of the queue on reaching adulthood, and must wait for older individuals to die in order to reach the front of the queue. While waiting, an individual may work for her group, in the process often risking her own survival and hence her chance of inheri- tance. Eventually, she may survive to reach the head of the queue and becomes the dominant of the group. Queueing has been particularly well-studied in hover wasps (Hymenoptera: Stenogastrinae). In hover wasp social groups, only one female lays eggs, and there is a strict, age-based queue to inherit the reproductive position. While the dominant individual (queen) concentrates on breeding, subordinate helpers risk death by foraging outside the nest, but have a slim chance of eventually inheriting dominance. Some explanations for this altruistic behavior and for the stability of social queues have been proposed and analyzed [Field et al., 2006; Kokko and Johnstone, 1999]. Since both the productivity of the nest and the chance to inherit the dominant position depend critically on group size, queueing dynamics are crucial for understanding social queues, but detailed analy- sis is lacking. Here, using hover wasps as an example, we demonstrate that some basic queueing theory[Toyoizumi, 2008] and non-homogeneous birth and death processes are useful for analyzing queueing dynamics and the population demographics of social queues. Our work leads to better understanding of how environmental conditions and strategic decision-making by individuals inter- act to produce the observed group dynamics; and in turn, how group dynamics affects individual decision-making.

  • 企業ネットワークにおける協調関係の進化の理論的研究

    2009  

     View Summary

    生物の中には、social&#9251;queueという社会構造を持つものがある。social&#9251;queueでは、新規に協 力した個体が、報酬(繁殖の機会)を得るのは、グループに貢献してからである。報酬の遅れが 社会構造の安定性と進化に寄与しているものと考えられる。しかし、そこには、報酬を得られな いことに関するリスクや、報酬の遅れに対する嫌悪感などのトレードオフが存在する。Social&#9251;qu eueの特性を知ることは、プリミティブな社会構造が、どのように高度に発展した社会の構造へ発 展していくのか、さらには、現在の人間社会の社会構造、ネットワーク構造を知る上で、貴重な 鍵を与えてくれる。本研究の代表者は、既に、social&#9251;queueを待ち行列的にモデル化し、little の公式を用いることにより、その一般的な特性を明らかにすることに成功した&#9251;

  • カリバチの社会学的待ち行列モデルの研究

    2007  

     View Summary

    Social queueでは、グループ内に明確な階級構造が見られ、queueの先頭(階級の頂点)にいる個体が、グループ内で優位な生活(生活サポート、独占的な繁殖活動等)を送ることができる。その他の個体は、queueの先頭になる順番を待ち、待つ間は、ヘルパーとしてグループの活動を支える。ヘルパーの活動は、生命の危険を伴い、ヘルパー自身の利益を損なうものも多い。どうして、生命の危険を犯してまでヘルパーとしてグループに加わるのかという疑問に対する満足な答えはまだみつかっていない。特にHairy-Faced Hover Waspが作るsocial queueは、年功序列型の厳格なsocial queue構造を持つことが知られている。本研究では、Hairy-Faced Hover Waspのsocial queueを数学的にモデル化し、その特性を分析した。

  • コンピュータウィルスのスケールフリーネットワークモデルによる最適コントロール問題

    2006  

     View Summary

    発信源のPCで保存されているメールアドレスを検索し、このアドレスを経由して拡散していくメール型のウィルスを取り上げる。メール型ウィルスは、メールアドレスの相互保持関係を基盤にする仮想的なメールアドレス空間上のネットワークを自律的に移動し、繁殖する粒子としてモデル化することができる。また、メールアドレスネットワークは、よく知られた階層型や完全ランダムなネットワークと異なり、small world networkの一種として考えることができるスケールフリーネットワークとしてモデル化することが可能である。本研究では、実際のネットワーク上を移動するコンピュータウィルスの活動を観測することにより、逆にメールアドレスネットワークの特性とメール型ウィルスの拡散ダイナミックスをモデル化する方法を検討した。最終的には、観測データから感染において重要な役割を担うハブノード(スーパー感染源)の位置を推定し、これらのノードへ防御を集中することにより、スケールフリーネットワークの構造をアクティブに変化させ、従来とは比較にならないほど、効果的な防衛戦略が実現する方法を提案した。

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Overseas Activities

  • 企業ネットワークにおける協調関係の進化の理論的研究

    2010.08
    -
    2011.07

    アメリカ   ハーバード大学

 

Syllabus

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