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  • Sep
    27

    IEMS Seminar: Optimal Routing to Remote Queues

    Department of Industrial Engineering and Management Sciences

    11:00 AM M228 Technological Institute

    EVENT DETAILS

    Yunana Liu

    North Carolina State University

    Title: Optimal Routing to Remote Queues

    Abstract:
    We develop optimal routing policies for remote queueing systems, in which each arrival, after being routed to join one of several single-server queues in parallel, will experience a pre-arrival delay. Motivated by service systems in which system state (e.g., queue length and waiting time) is available for routing decisions, we intend to use pre-arrival delays to model commute times of arrivals, such as patients' transportation times before arriving at clinics and data packets' transmission times to web servers. For parallel queues with no pre-arrival delays, it is well known that the join-the-shortest queue (JSQ) routing policy is asymptotically optimal in minimizing the total queue length and in-queue waiting time. In addition, under JSQ the performance of the parallel system with no pre-arrival delays is asymptotically equivalent to the pooled system in heavy traffic. In the presence of pre-arrival delays, unfortunately, JSQ can be disastrous for the system performance, causing excessively large in-queue waiting time and an undesired bouncing effect (having negatively correlated queue performance). In order to reduce the waiting time and to minimize the total queue length, we propose a new state-dependent probabilistic routing policy, named JSQ with a root-excess bias (JSQ-REB). Specifically, JSQ-REB means that we route a customer to the shortest queue with a slight bias that is proportional to the square root of the fraction of idleness (i.e., one minus the traffic intensity). We prove a heavy-traffic limit theorem by showing that, under the proposed JSQ-REB policy, the parallel system is asymptotically equivalent to the pooled system as the traffic intensity approaches one, so that both the waiting time and total queue length are minimized, and the excessive congestion caused by pre-arrival delays is eliminated.

    Mini-bio:
    Yunan Liu is an assistant professor at the Industrial and Systems Engineering Department and an associate faculty member of the Operations Research Center of North Carolina State University. His research interests include queueing theory, stochastic modeling, applied probability, simulation, and their applications in service systems including call centers, healthcare, and manufacturing systems. He received his M.S. and Ph.D. in Operations Research from Columbia University and B.S. in Electrical Engineering from Tsinghua University.

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    TIME Tuesday, September 27, 2016 at 11:00 AM - 12:00 PM

    LOCATION M228 Technological Institute    map it

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    CONTACT Agnes Kaminski    a-kaminski@northwestern.edu EMAIL

    CALENDAR Department of Industrial Engineering and Management Sciences

  • Apr
    30

    Learning and Information Aggregation in Dynamic Games

    Department of Industrial Engineering and Management Sciences (IEMS)

    11:00 AM ITW 1.350, Ford Motor Company Engineering Design Center

    EVENT DETAILS

    TIME Tuesday, April 30, 2024 at 11:00 AM - 12:00 PM

    LOCATION ITW 1.350, Ford Motor Company Engineering Design Center    map it

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    CONTACT Kendall Minta    kendall.minta@gmail.com EMAIL

    CALENDAR Department of Industrial Engineering and Management Sciences (IEMS)

  • May
    8

    Extending Care: A Conversation about Conservation and Futurity

    Block Museum of Art

    6:00 PM Block Museum of Art, Mary and Leigh

    EVENT DETAILSmore info

    TIME Wednesday, May 8, 2024 at 6:00 PM - 7:30 PM

    LOCATION Block Museum of Art, Mary and Leigh    map it

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    CONTACT Block Museum of Art    block-museum@northwestern.edu EMAIL

    CALENDAR Block Museum of Art

  • Jun
    10

    Northwestern Engineering PhD Hooding and Master's Degree Recognition Ceremony

    McCormick School of Engineering and Applied Science

    9:00 AM Welsh-Ryan Arena

    EVENT DETAILSmore info

    TIME Monday, June 10, 2024 at 9:00 AM - 11:00 AM

    LOCATION Welsh-Ryan Arena   

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    CONTACT Amy Pokrass    amy.pokrass@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science

  • Jun
    10

    Northwestern Engineering Undergraduate Convocation

    McCormick School of Engineering and Applied Science

    2:00 PM Welsh-Ryan Arena

    EVENT DETAILSmore info

    TIME Monday, June 10, 2024 at 2:00 PM - 4:00 PM

    LOCATION Welsh-Ryan Arena   

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    CONTACT Amy Pokrass    amy.pokrass@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science

  • Aug
    14

    Undergraduate Quantum Summer School

    McCormick School of Engineering and Applied Science

    All Day Ford Motor Company Engineering Design Center

    EVENT DETAILSmore info

    TIME Wednesday, August 14, 2024

    LOCATION Ford Motor Company Engineering Design Center    map it

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    CONTACT Dongyang Li    lidongyang@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science

  • Aug
    15

    Undergraduate Quantum Summer School

    McCormick School of Engineering and Applied Science

    All Day Ford Motor Company Engineering Design Center

    EVENT DETAILSmore info

    TIME Thursday, August 15, 2024

    LOCATION Ford Motor Company Engineering Design Center    map it

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    CONTACT Dongyang Li    lidongyang@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science