Works (32)

Updated: April 5th, 2024 08:03

2024 journal article

Mail back or in-store dropoff? Optimal design of product-exchange policies in omnichannel retailing systems

OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE, 125.

By: K. Sun*, Y. Liu n & X. Li*

author keywords: Queueing theory; Queueing economics model; Retailing system; Omnichannel retailing; Product exchange policy
TL;DR: This work investigates the implications of both online and onsite exchange policies in the setting of a queueing model that offers omnichannel services and discovers that online exchange becomes an inferior policy relative to in-store exchange when the market size is large. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: March 11, 2024

2023 article

An Online Learning Approach to Dynamic Pricing and Capacity Sizing in Service Systems

Chen, X., Liu, Y., & Hong, G. (2023, June 12). OPERATIONS RESEARCH.

By: X. Chen*, Y. Liu n & G. Hong*

author keywords: online learning in queues; service systems; capacity planning; staffing; pricing in service systems
Source: Web Of Science
Added: July 3, 2023

2023 article

An Online Learning Approach to Dynamic Pricing and Capacity Sizing in Service Systems

Chen, X., Liu, Y., & Hong, G. (2023, June 12). OPERATIONS RESEARCH.

By: X. Chen*, Y. Liu n & G. Hong*

author keywords: online learning in queues; service systems; capacity planning; staffing; pricing in service systems
TL;DR: GOLiQ prescribes an efficient procedure to obtain improved decisions in successive cycles using newly collected queueing data, and is advantageous when focusing on performance optimization in the long run because its data-driven nature enables it to constantly produce improved solutions which will eventually reach optimality. (via Semantic Scholar)
Source: Web Of Science
Added: July 10, 2023

2023 article

Improving Workers' Musculoskeletal Health During Human-Robot Collaboration Through Reinforcement Learning

Xie, Z., Lu, L., Wang, H., Su, B., Liu, Y., & Xu, X. (2023, May 22). HUMAN FACTORS, Vol. 5.

By: Z. Xie n, L. Lu n, H. Wang n, B. Su n, Y. Liu n & X. Xu n

author keywords: robotics; computer-supported collaborations; human-automation interaction; job risk assessment; human-robot interaction
TL;DR: The proposed model-free reinforcement learning method can learn the optimal worker postures without the need for specific biomechanical models and can be applied to improve the occupational safety in robot-implemented factories. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Sources: Web Of Science, ORCID, NC State University Libraries
Added: May 23, 2023

2023 article

Optimal interventions of infectious disease

Sun, X., & Liu, Y. (2023, April 19). NAVAL RESEARCH LOGISTICS.

By: X. Sun* & Y. Liu n

author keywords: benefit-cost analysis; infectious diseases; non-pharmaceutical interventions; optimal control
TL;DR: An optimal control problem for an infectious disease model, wherein the social planner can control the transmission rate by implementing or lifting lockdown measures, is proposed and extended to cases where the social planner may implement multiple lockdown levels. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: May 9, 2023

2022 journal article

Energy harvesting cognitive radio networks with strategic users: A two-class queueing model with retrials

COMPUTER COMMUNICATIONS, 199, 98–112.

By: K. Sun*, Y. Liu n & K. Li*

author keywords: Cognitive radio network; Queueing system; Energy harvesting; Nash equilibrium; Retrial queues; Strategic customers
UN Sustainable Development Goal Categories
7. Affordable and Clean Energy (OpenAlex)
Source: Web Of Science
Added: January 23, 2023

2022 journal article

Make waiting not to seem like waiting: Capacity management of waiting-area entertainment

OPERATIONS RESEARCH LETTERS, 50(6), 745–752.

By: K. Sun*, Y. Liu n & X. Li*

author keywords: Queueing economics model; Psychology of waiting lines; Waiting -area entertainment; Strategic customers
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: December 19, 2022

2022 article

Pay to activate service in vacation queues

Wang, Z., Liu, Y., & Fang, L. (2022, March 31). PRODUCTION AND OPERATIONS MANAGEMENT.

By: Z. Wang*, Y. Liu n & L. Fang*

author keywords: equilibrium analysis; N-policy; pay to activate service; strategic customers; vacation queue
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: April 8, 2022

2022 journal article

Routing and staffing in emergency departments: A multiclass queueing model with workload dependent service times

IISE TRANSACTIONS ON HEALTHCARE SYSTEMS ENGINEERING, 13(1), 46–61.

By: S. Nambiar n, M. Mayorga n & Y. Liu n

author keywords: Simulation; fluid approximation; queueing model; patient flow
TL;DR: This work model a multiclass multiserver queueing system where patients of varying acuity receive care from one of several wards, each ward is attended by several nurses who work as a team, and incorporates state-dependent service times into the model. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Sources: Web Of Science, NC State University Libraries
Added: November 6, 2023

2021 journal article

A discrete-event simulation model for the Bitcoin blockchain network with strategic miners and mining pool managers

COMPUTERS & OPERATIONS RESEARCH, 134.

By: K. Li n, Y. Liu n, H. Wan n & Y. Huang n

author keywords: Blockchain; Discrete-event simulation; Bitcoin mining policy; Mining competition
TL;DR: This work investigates the miners’ and mining pool managers’ decisions in repeated Bitcoin mining competitions by building a Monte-Carlo discrete-event simulation model, which characterizes the system-level dynamics of the blockchain in terms of the mining difficulty level and total mining power. (via Semantic Scholar)
Source: Web Of Science
Added: July 26, 2021

2021 journal article

A little bit flexibility on headway distribution is enough: Data-driven optimization of subway regenerative energy

INFORMATION SCIENCES, 554, 276–296.

By: X. Li*, B. Zhang* & Y. Liu n

author keywords: Subway; Regenerative energy; ATO data; Headway distribution; Improved genetic algorithm
TL;DR: A new optimization method driven by real ATO data for maximizing subway regenerative energy based on a concept of uniformity to measure the homogeneous degree of headway distribution is developed and an improved genetic algorithm with multiple crossover and mutation operators to search for near-optimal solutions is proposed. (via Semantic Scholar)
UN Sustainable Development Goal Categories
7. Affordable and Clean Energy (OpenAlex)
Source: Web Of Science
Added: March 15, 2021

2021 article

Mind your own customers and ignore the others: Asymptotic optimality of a local policy in multi-class queueing systems with customer feedback

Yang, J., Huang, J., & Liu, Y. (2021, July 25). IISE TRANSACTIONS.

By: J. Yang, J. Huang & Y. Liu

author keywords: Multi-class queueing systems; asymptotic optimality; customer feedback; local information; convex delay cost; cl-rule
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: September 20, 2021

2021 article

Scheduling to Differentiate Service in a Multiclass Service System

Liu, Y., Sun, X., & Hovey, K. (2021, March 8). OPERATIONS RESEARCH.

By: Y. Liu n, X. Sun* & K. Hovey*

author keywords: dynamic scheduling; dynamic prioritization; time-varying staffing; efficiency-driven; heavy-traffic approximations; service differentiation; tail probability of delay
TL;DR: Dynamic Scheduling to Differentiate Delay-Based Service Levels in Multiclass Service Systems is presented, which aims to demonstrate the power of dynamic scheduling in solving the challenge of heterogeneity in service levels. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: November 1, 2021

2020 article

CAPTURING MINER AND MINING POOL DECISIONS IN A BITCOIN BLOCKCHAIN NETWORK: A TWO-LAYER SIMULATION MODEL

2020 WINTER SIMULATION CONFERENCE (WSC), pp. 3152–3163.

By: K. Li n, Y. Liu n, H. Wan n & L. Zhang n

TL;DR: A Monte-Carlo simulation model is built to study the miners’ and mining pool managers’ decisions in the Bitcoin blockchain network and characterize the system-level dynamics of the blockchain in terms of mining difficulty level and total hashing power. (via Semantic Scholar)
Source: Web Of Science
Added: August 30, 2021

2020 journal article

Reducing Delay in Retrial Queues by Simultaneously Differentiating Service and Retrial Rates

OPERATIONS RESEARCH, 68(6), 1648–1667.

By: J. Wang*, Z. Wang* & Y. Liu n

author keywords: retrial queues; simultaneous service-and-retrial differentiation; service differentiation
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: November 30, 2020

2020 journal article

Staffing many-server queues with autoregressive inputs

NAVAL RESEARCH LOGISTICS, 68(3), 312–326.

By: X. Sun* & Y. Liu n

author keywords: autocorrelation; heavy‐ traffic approximations; many‐ server queues; mean‐ reverting process; non‐ Poisson arrivals; optimal staffing; parameter uncertainty; queues with customer abandonment
TL;DR: A multiserver queueing system where customer arrivals follow a doubly stochastic Poisson point process whose intensities are driven by a Cox–Ingersoll–Ross (CIR) process is studied, finding that, in order to achieve the designated service level, such an autoregressive feature in the arrival model translates into notable adjustment in the staffing formula, and such an adjustment can be fully characterized by the parameters of the new arrival model. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: November 30, 2020

2020 article

To Pool or Not to Pool: Queueing Design for Large-Scale Service Systems

Cao, P., He, S., Huang, J., & Liu, Y. (2020, December 3). OPERATIONS RESEARCH.

By: P. Cao*, S. He*, J. Huang* & Y. Liu n

author keywords: dedicated queue; join-the-shortest-queue; power-of-d; join-idle-queues; customer abandonment; overloaded queue; many-server heavy-traffic limit
TL;DR: “To Pool or Not to Pool: Queueing Design for Large-Scale Service Systems” demonstrates that the dedicated queue structure, under which each server has her own queue, could be more advantageous for improving the system’s service level. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: November 8, 2021

2019 journal article

Modeling and Simulation of Nonstationary Non-Poisson Arrival Processes

INFORMS JOURNAL ON COMPUTING, 31(2), 347–366.

By: R. Liu*, M. Kuhl*, Y. Liu n & J. Wilson n

author keywords: nonstationary arrival process; non-poisson process; time-dependent arrival rate; dispersion radio; index of dispersion for counts
TL;DR: CIATA, a combined inversion-and-thinning approach for modeling a nonstationary non-Poisson process (NNPP), where the target arrival process is described by a given rate function and its ... (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: June 17, 2019

2018 journal article

Many-server Gaussian limits for overloaded non-Markovian queues with customer abandonment

Queueing Systems, 89(1-2), 81–125.

By: A. Aras*, X. Chen* & Y. Liu n

UN Sustainable Development Goal Categories
Source: NC State University Libraries
Added: August 6, 2018

2018 journal article

Staffing to Stabilize the Tail Probability of Delay in Service Systems with Time-Varying Demand

OPERATIONS RESEARCH, 66(2), 514–534.

By: Y. Liu n

author keywords: staffing algorithms; service systems; capacity planning; many-server queues; efficiency-driven; time-varying arrivals; queues with abandonment; nonstationary queues; nonexponential distributions
TL;DR: Analytic formulas are developed to set the time-dependent number of servers to stabilize the tail probability of customer waiting times for the Gt/GI/st + GI queueing model, which has a nonstationary non-Poisson arrival process, nonexponential service times, and allows customer abandonment according to a nonexp exponential patience distribution. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2017 journal article

Allocation heuristics for high-altitude long- endurance UAV image intelligence platforms

Military Operations Research, 22(3), 5–19.

By: G. Kim, T. Hodgson, R. King, Y. Liu & M. Kay

Source: NC State University Libraries
Added: August 6, 2018

2017 journal article

Functional law of the iterated logarithm for multi-server queues with batch arrivals and customer feedback

ANNALS OF OPERATIONS RESEARCH, 264(1-2), 157–191.

By: Y. Guo*, Y. Liu n & R. Pei*

author keywords: Functional law of the iterated logarithm; Multi-server queue; Batch arrival; Customer feedback; Nonexponential service times; Strong approximation
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2016 journal article

Approximations for Heavily Loaded G/GI/n plus GI Queues

NAVAL RESEARCH LOGISTICS, 63(3), 187–217.

By: Y. Liu n, W. Whitt* & Y. Yu n

author keywords: many-server queues; queues with customer abandonment; queuing performance approximations; steady-state performance; queues with non-exponential distributions
TL;DR: Simulation experiments show that the proposed approximations are effective for large‐scale queuing systems for a significant range of the traffic intensity ρ and the abandonment rate θ, roughly for ρ > 1.02 and θ > 2.0. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2016 journal article

STAFFING A SERVICE SYSTEM WITH NON-POISSON NON-STATIONARY ARRIVALS

PROBABILITY IN THE ENGINEERING AND INFORMATIONAL SCIENCES, 30(4), 593–621.

By: B. He, Y. Liu* & W. Whitt

TL;DR: A general model of the non-Poisson non-stationary arrival process is developed that includes as a special case the non -stationary Cox process (a modification of a Poisson process in which the rate itself is a non- stationary stochastic process), which has been advocated in the literature. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2016 journal article

Stabilizing performance in a service system with time-varying arrivals and customer feedback

EUROPEAN JOURNAL OF OPERATIONAL RESEARCH, 256(2), 473–486.

By: Y. Liu n & W. Whitt*

author keywords: Queueing; Staffing algorithms for service systems; Time-varying arrival rates; Queues with feedback; Stabilizing performance
Source: Web Of Science
Added: August 6, 2018

2014 journal article

A law of iterated logarithm for multiclass queues with preemptive priority service discipline

QUEUEING SYSTEMS, 79(3-4), 251–291.

By: Y. Guo* & Y. Liu n

author keywords: Law of iterated logarithm; Multiclass queues; Priority queues; Preemptive-resume discipline; Non-Markovian queues; Strong approximation
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2014 journal article

MANY-SERVER HEAVY-TRAFFIC LIMIT FOR QUEUES WITH TIME-VARYING PARAMETERS

ANNALS OF APPLIED PROBABILITY, 24(1), 378–421.

By: Y. Liu n & W. Whitt n

author keywords: Many-server queues; queues with time-varying arrivals; nonstationary queues; customer abandonment; nonexponential patience distribution; heavy traffic; functional central limit theorem; Gaussian approximation; deterministic fluid approximation
Source: Web Of Science
Added: August 6, 2018

2014 journal article

STABILIZING PERFORMANCE IN NETWORKS OF QUEUES WITH TIME-VARYING ARRIVAL RATES

PROBABILITY IN THE ENGINEERING AND INFORMATIONAL SCIENCES, 28(4), 419–449.

By: Y. Liu n & W. Whitt*

TL;DR: It is shown that index of dispersion for counts is effective for determining when a departure process is approximately an NHPP in this setting, and both the algorithm and the algorithm are effective. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2013 journal article

Algorithms for Time-Varying Networks of Many-Server Fluid Queues

INFORMS JOURNAL ON COMPUTING, 26(1), 59–73.

By: Y. Liu n & W. Whitt*

author keywords: queues with time-varying arrival rates; nonstationary queues; queueing networks; many-server queues; deterministic fluid models; fluid approximation; nonstationary networks of fluid queues; customer abandonment; non-Markovian queues
TL;DR: A new algorithm is developed for the previous model and generalize the model to include non-exponential service-time distributions, to confirm that the algorithms are effective in computing the performance functions and that these performance functions provide useful approximations for the corresponding stochastic models. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2012 journal article

A many-server fluid limit for the G(t)/GI/s(t) + GI queueing model experiencing periods of overloading

OPERATIONS RESEARCH LETTERS, 40(5), 307–312.

By: Y. Liu n & W. Whitt n

author keywords: Many-server heavy-traffic limit; Functional weak law of large numbers; Queues with time-varying arrivals; Nonstationary queues; Deterministic fluid model; Non-Markovian queues
UN Sustainable Development Goal Categories
16. Peace, Justice and Strong Institutions (OpenAlex)
Source: Web Of Science
Added: August 6, 2018

2012 journal article

Stabilizing Customer Abandonment in Many-Server Queues with Time-Varying Arrivals

OPERATIONS RESEARCH, 60(6), 1551–1564.

By: Y. Liu n & W. Whitt*

TL;DR: An algorithm is developed to determine time-dependent staffing levels to stabilize the time- dependent abandonment probabilities and expected delays at positive target values in the Mt/GI/st + GI many-server queueing model, which has a nonhomogeneous Poisson arrival process. (via Semantic Scholar)
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018

2012 journal article

The G(t)/GI/s(t)+GI many-server fluid queue

QUEUEING SYSTEMS, 71(4), 405–444.

By: Y. Liu n & W. Whitt*

author keywords: Queues with time-varying arrivals; Nonstationary queues; Transient behavior; Many-server queues; Deterministic fluid model; Customer abandonment; Non-Markovian queues
TL;DR: A deterministic fluid model has time-varying arrival rate and service capacity, abandonment from queue, and non-exponential service and patience distributions, and an algorithm is developed to calculate all performance functions. (via Semantic Scholar)
Source: Web Of Science
Added: August 6, 2018

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