University of TsukubaApplied Stochastic
Systems Lab.

Welcome message

Our research areas are around Applied Probability, Stochastic Process, Queueing Theory and their applications in Stochastic Systems. We have been developing models for call centers, data centers and 5g communication systems. We are also interested in developing new mathematical tools for analyzing stochastic models arising from real world systems. Some keywords of our research are as follows.

Methodologies: Applied Probability, Mathematical Engineering, Stochastic Models, Queueing Theory, Mathematical Models

Applications: Service Management, Information Systems, Resource Sharing Systems

We are very open, having been collaborating with many leading researchers in more than ten countries of four continents in the world! Please do not hesitate to contact us for possible collaboration or for joining our group as a member.

Information

Ayane Nakamura (M2) Yoshito Machida (M2) Zhuangling Luo (M2) Tianqi Zhao (M2) obtained Master's degree and Tomoko Masui Shoma Nishio got Bachelor's degree. Ayane Nakamura received President's award and Yoshito Machida received Degree Program's leader Award. Congratulations! NEW
Our papers were accepted.
Nazarov, A., Phung-Duc, T., Paul, S. and Lizura, O.,“Diffusion Limit for Single-Server Retrial Queues with Renewal Input and Outgoing Calls,” Mathematics, Vol. 10, No. 6, Article no. 948, 2022.
*Nguyen, Q. H. and Phung-Duc, T., “Strategic customer behavior and optimal policies in a passenger-taxi double-ended queueing system with multiple access points and non-zero matching times,” to appear in Queueing Systems, 2022. NEW
Hung Q. Nguyen, Yoshito Machida gave presentations at The 2022 Spring National Conference of Operations Research Society of Japan, March 17-18, 2022. NEW
Our paper was accepted.Phung-Duc, T., *Akutsu, K., Kawanishi, K., Salameh, O. and Wittevrongel, S. (2021), “Queueing models for cognitive wireless networks with sensing time of secondary users,” to appear in Annals of Operations Research. NEW
We submitted two papers.
Yajima, M. and Phung-Duc, T. (2021), “A survey on queues with variable service speeds: Exact results and scaling limits,” Submitted.
*Nguyen, Q. H. and Phung-Duc, T. (2021), “Two-part equilibria of supply-demand and multivariate optimization of social welfare in double-ended queueing systems,” Submitted. NEW
Kazuma Abe (M1), Masato Obinata (M1), Runze Miao (Research Student) joined our group. Congratulations! NEW
Our paper was accepted: Makino, Y., Phung-Duc, T. and Machida, F. (2021), “A Queueing Analysis of Multi-model Multi-input Machine Learning Systems,” to appear in Proceedings of The 4th DSN Workshop on Dependable and Secure Machine Learning (DSN-DSML'21), Taipei, Taiwan, 21 June 2021. NEW
Our paper was published: Sakuma, Y., Boxma, O. and Phung-Duc, T., “An M/PH/1 queue with workload-dependent processing speed and vacation,” Published online in Queueing Systems, 2021. NEW
Yudai Makino got the Master degree and started his new career! Congratulations! NEW
Tuan Phung-Duc joined the editorial board of MDPI Mathematics (Impact factor: 1.747). NEW
We have published more than 100 refereed papers. Thanks all people who supported us! NEW
We gave 5 presentations (Nakamura et al., H. Q. Nguyen et al, Makino et al., Kawamura et al.) at the Queueing Symposium 2021. NEW
According to Google Scholar, our H-Index is 20 now. Thanks all people who supported us! NEW
Tomoko Masui, Shoma Nishio, Keigo Nishikawa, Haruka Hayashi joined our lab. NEW
Ayane Nakamura received Student Paper Award for the following paper. Congratulations!
*Nakamura, A., Phung-Duc, T. and Ando, H. (2020), “A Stochastic Model for Car/Ride-Share Service by a Bus Company,” to be presented at NOLTA2020. NEW
Our publications have received more than 1000 citations. NEW
The following papers were accepted at DCCN' 20.
Nazarov, A., Phung-Duc, T., Paul, S. and Lizura, O., (2020), “Asymptotic-Diffusion Analysis of Multiserver Retrial Queue with Two-Way Communication,” Accepted.
Nazarov, A., Phung-Duc, T. and Izmailova, Y. (2020), “Gaussian asymptotics for a multiclass M/M/1 retrial queueing system,” Accepted. NEW
The following paper was accepted for presentation at NOLTA2020.
*Nakamura, A., Phung-Duc, T. and Ando, H. (2020), “A Stochastic Model for Car/Ride-Share Service by a Bus Company,” to be presented at NOLTA2020. NEW
We submitted the following paper to an international conference.
Nazarov, A., Phung-Duc, T., Paul, S. and Lizura, O., (2020), “Asymptotic-Diffusion Analysis of Multiserver Retrial Queue with Two-Way Communication,” Submitted. NEW
We submitted the following paper to a journal.
Morozov, E., Rogozin, S. Nguyen, Q. H., Phung-Duc, T. (2020), “Modified Erlang loss system for cognitive wireless networks,” Submitted. NEW
The following paper was accepted in QEST2020.
M. A. Yazici, T. Phung-Duc, M/M/1 Vacation Queue with Multiple Thresholds: A Fluid Analysis, to be presented at QEST2020 and to appear in Lecture Notes in Computer Science. NEW
We submitted the following paper to a conference.
*Nakamura, A., Phung-Duc, T. and Ando, H. (2020), “A Stochastic Model for Car/Ride-Share Service by a Bus Company,” Submitted. NEW
We submitted the following paper to a conference.
Nazarov, A., Phung-Duc, T. and Izmailova, Y. (2020), “Gaussian asymptotics for a multiclass M/M/1 retrial queueing system,” Submitted. NEW
We submitted the following paper to a conference.
M. A. Yazici, T. Phung-Duc, M/M/1 Vacation Queue with Multiple Thresholds: A Fluid Analysis. NEW
We editted the following special issue.
Phung-Duc, T., Takahashi, Y. and Takagi, H. Eds., Special Issue of Annals of Operations Research on Queueing theory and network applications II, 2020. [DOI: 10.1007/s10479-020-03618-4] NEW
Tuan Phung-Duc joined the Panel Session: Analysis on Stochastic Service Systems with Strategic Service Providers and Customers of 2020 IEEE 7th International Conference on Industrial Engineering and Applications (ICIEA 2020) as an invited panelist and gave an invited talk entitled Queueing Analysis of Autoscaling Systems. NEW
Three new members: Nguyen Quoc Hung (Doctoral course), Zhuangling Luo (Master course) Tianqi Zhao (Master course) joined our lab. Congratulations!!!NEW
Moeko Yajima became an assistant professor of Tokyo Institute of Technology. Congratulations!!!NEW
Kohei Akutsu and Shinto Hideyama graduated and started their new careers. Congratulations!!!NEW
Kohei Akutsu (M2) received department chair's award,Ayane Nakamura (B4) received the Kuratani Award and the University of Tsukuba's President Award!Congratulations!!!NEW
Shinto Hideyama and Kohei Akutsu received Master Degree; Ayane Nakamura and Yoshito Machida received Batchelor Degree. Congratulations!NEW
Tuan Phung-Duc editted his forth book.NEW
Gribaudo, M., Iacono, M., Phung-Duc, T., Razumchik, R. (Eds.): Computer Performance Engineering: 16th European Workshop, EPEW 2019, Milan, Italy, November 28–29, 2019, Revised Selected Papers (Lecture Notes in Computer Science).
We submitted two papers to a journal. NEW
*Nakamura, A., Phung-Duc, T. and Ando, H. (2020), “Queueing Analysis of a Car/Ride-Share System,” Submitted.
Phung-Duc, T., *Akutsu, K., Kawanishi, K., Salameh, O. and Wittevrongel, S. (2020), “Queueing models for cognitive wireless networks with sensing time of secondary users,” Submitted.
The following paper was accepted by ASMTA2019 and to appear in Lecture Notes in Computer Science.  
Phung-Duc, T. and Fiems, D. (2019), “Exact Performance Analysis of Retrial Queues with Collisions,” Accepted in ASMTA2019 and to appear in Lecture Notes in Computer Science. NEW
The following paper was accepted by ASMTA2019 and to appear in Lecture Notes in Computer Science.  
Ayane Nakamura, Tuan Phung-Duc and Hiroyasu Ando, “Queueing Analysis for a mixed model of carsharing and ridesharing,” Accepted in ASMTA2019. NEW
The following paper was accepted by ASMTA2019 and to appear in Lecture Notes in Computer Science. 
Velika Dragieva and Tuan Phung-Duc, “Queueing Analysis of Cognitive Radio Networks with Finite Number of Secondary Users,” Accepted in ASMTA2019. NEW
4th Year Batchelor Student Ayane Nakamura gave the following presentation. 
Ayane Nakamura, Tuan Phung-Duc, Hiroyasu Ando, “Mixed Model for Carsharing and RideSharing,” The 2019 Fall National Conference of Operations Research Society of Japan. NEW
Yutaka Sakuma, Tuan Phung-Duc and Onno Boxma received the Best Paper Award at QTNA2019 for the following paper. 
Sakuma, Y., Boxma, O. and Phung-Duc, T. (2019), “A single server queue with workload-dependent service speed and vacations,” QTNA2019. NEW
Master Student Shinto Hideyama gave the following presentation at QTNA2019. 
*Hideyama, S., Phung-Duc, T. and Okada, Y., “Queueing Analysis of Home Delivery Services with Parcel Lockers,” QTNA2019. NEW
Master Student of Second Year Kohei Akutsu gave the following presentation at QTNA2019. 
*Akutsu, K., Phung-Duc, T. (2019), “Analysis of Retrial Queues for Cognitive Wireless Networks with Sensing Time of Secondary Users,” QTNA2019. NEW
The paper: Dragieva, V. I. and Phung-Duc, T., “A Finite-Source M/G/1 Retrial Queue with Outgoing Calls,” was accepted in Annals of Operations Research. NEW
The paper: *Makino, Y. and Phung-Duc, T. (2019), “Queueing Analysis of Taxi Stand Considering Boarding Time,” was accepted by NOLTA2019. NEW
Prof. Tuan Phung-Duc became an associate editor of Journal of the Operations Research Society of Japan. NEW
Prof. Tuan Phung-Duc is serving as TPC Co-Chair of 16th European Performance Engineering Workshop (EPEW2019). NEW
Prof. Tuan Phung-Duc is serving as General Chair of 13th EAI International Conference on Performance Evaluation Methodologies and Tools (Valuetools2020). NEW
Prof. Moshe Haviv visits us and delivers a series of intensive lectures on Economics of Queues. Further, he will give a talk entitled ``Social cost of deviation in non-cooperative games". NEW
Master Student Kohe Akutsu received the travel grant from The International Information Science Foundation. NEW
Prof. Ying-Dar Lin visited us and gave the talk entitled "5G Mobile Edge Computing: Research Roadmap of H2020 5G-Coral Project" NEW
The paper: Phung-Duc, T. and Kawanishi, K., “Delay Performance of Data-Center Queue with Setup Policy and Abandonment,” was accepted by Annals of Operations Research. NEW
Three papers of our group were accepted by QTNA2019 and to appear in Lecture Notes in Computer Science. 
Sakuma, Y., Boxma, O. and Phung-Duc, T. (2019), “A single server queue with workload-dependent service speed and vacations,” Accepted by QTNA2019. To appear in Lecture Notes in Computer Science.
*Hideyama, S., Phung-Duc, T. and Okada, Y. (2019), “Queueing Analysis of Home Delivery Services with Parcel Lockers,” Accepted by QTNA2019. To appear in Lecture Notes in Computer Science.
*Akutsu, K., Phung-Duc, T. (2019), “Analysis of Retrial Queues for Cognitive Wireless Networks with Sensing Time of Secondary Users,” Accepted by QTNA2019. To appear in Lecture Notes in Computer Science. NEW
We opened our website. NEW
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