BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Haoran Wu (University of Waterloo) DTSTART:20200821T153000Z DTEND:20200821T160000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/1 DESCRIPTION:Title: Double-Sided Queues with Marked Markovian Arrival Processes an d Abandonment\nby Haoran Wu (University of Waterloo) as part of BIRS w orkshop: Canadian Queueing Theorists and Practitioners Conference\n\n\nAbs tract\nIn this paper\, we study a double-sided queueing model with marked Markovian arrival processes and finite discrete abandonment times. We appl y the theory of multi-layer Markov modulated fluid flow (MMFF) processes t o analyze the queueing model. First\, we define three age processes for th e queueing system and convert them into a multi-layer MMFF process. Then w e analyze the multi-layer MMFF process to find queueing performance measur es related to the age processes\, matching rates/probabilities\, waiting t imes\, and queue lengths for both sides of the queueing system. We obtain a number of aggregate quantities as well as quantities for individual type s of inputs\, which can be useful for the analysis and design of\, for exa mples\, passenger-taxi service systems and organ transplantation systems.\ n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Qi-Ming He (University of Waterloo) DTSTART:20200821T160000Z DTEND:20200821T163000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/2 DESCRIPTION:Title: Bounds on the Mean and Squared Coefficient of Variation of Pha se-Type Distributions\nby Qi-Ming He (University of Waterloo) as part of BIRS workshop: Canadian Queueing Theorists and Practitioners Conference \n\n\nAbstract\nWe consider a class of phase-type distributions\, to be ca lled the MMPP class of PH-distributions\, and find bounds of their mean an d squared coefficient of variation (SCV). As an application\, we have show n that the SCV of the event-stationary inter-event time of Markov modulate d Poisson processes (MMPPs) is greater than or equal to unity\, which answ ers an open problem about MMPPs\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Barbara Margolius (Cleveland State University) DTSTART:20200821T163000Z DTEND:20200821T170000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/3 DESCRIPTION:Title: Catastrophes and Queueing Systems with Time-Varying Periodic T ransition Rates\nby Barbara Margolius (Cleveland State University) as part of BIRS workshop: Canadian Queueing Theorists and Practitioners Confe rence\n\n\nAbstract\nWe study the asymptotic periodic distribution of queu es with time-varying periodic transition rates and catastrophes that occur randomly according to an exponential distribution with time-varying perio dic rate. When a disaster occurs\, the system resets\, all customers are l ost and an exponentially distributed period of time elapses before the rep air is complete. Service is governed by a phase distribution. The asymptot ic periodic distribution of the queue process is analogous to the steady s tate distribution for a system with constant transition rates.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Suman Thapa (Carleton University) DTSTART:20200821T180000Z DTEND:20200821T183000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/5 DESCRIPTION:Title: Construction of New Copulas with Applications to Queueing Mode ls\nby Suman Thapa (Carleton University) as part of BIRS workshop: Can adian Queueing Theorists and Practitioners Conference\n\n\nAbstract\nIn th is paper\, we construct the bound copula\, which can reach both Frechet's lower and upper bounds for perfect positive and negative dependence cases. Since it has a wide range of dependency\, it can be very useful. This new copula is simple for the computational purpose. It is very difficult to u se copulas such as Archemedes\, Guassian\, t-copula to find the distributi on function and the expected value in explicit form. For both copulas\, we derive the strength of measures of the dependency such as Spearman's rho\ , Kendall's tau\, Blomqvist's beta and Gini's gamma\, and the coefficients of the tail dependency. For the application part\, we analyze the depende ncy between two service times to evaluate the mean waiting time and the me an service time when customers launch two replicas of each task on two par allel servers using the cancel-on-finish policy. We assume that the inter- arrival time is exponential and the service time is general.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Myron Hlynka (University of Windsor) DTSTART:20200821T200000Z DTEND:20200821T203000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/6 DESCRIPTION:Title: Completing a Task with Interruptions\nby Myron Hlynka (Uni versity of Windsor) as part of BIRS workshop: Canadian Queueing Theorists and Practitioners Conference\n\n\nAbstract\nAssume that the time to comple te a task without interruption is T. Assume interruptions occur according to a Poisson process with rate lambda. If a process is interrupted\, it mu st begin again. Let W be the total time to completion. We find the Laplace transform of W. One application is a solution of the classic problem of t he time to cross a one way street assuming Poisson traffic.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Amir Rastpour (Ontario Tech University) DTSTART:20200821T203000Z DTEND:20200821T210000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/7 DESCRIPTION:Title: Algorithms for Queueing Systems with Reneging and Priorities M odeled as Quasi-Birth-Death Processes\nby Amir Rastpour (Ontario Tech University) as part of BIRS workshop: Canadian Queueing Theorists and Prac titioners Conference\n\n\nAbstract\nAlgorithms for queueing systems with r eneging and priorities modeled as quasi-birth-death processes By Amir Rast pour\, Ontario Tech. University Abstract: We develop an iterative algorith m for a class of infinite level-dependent quasi-birth-and-death (LDQBD) sy stems. The class of queueing systems that we focus on includes the Erlang A system with two priority classes where customers from both classes are i mpatient\, and they can have different arrival\, service\, and abandonment rates. Our algorithm provides upper and lower bounds for stationary proba bilities and automatically proceeds until a pre-specified error tolerance is achieved. Our algorithm exploits an approach that can be used to obtain element-wise bounds for the rate matrix of any LDQBD system within any de sired error tolerance. We generate a wide range of instances and perform n umerical analyses on them. We report numerical results and discuss algorit hm limitation\, accuracy and speed.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Douglas Down (McMaster University) DTSTART:20200821T210000Z DTEND:20200821T213000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/8 DESCRIPTION:Title: Size-based Scheduling with Estimation Errors\nby Douglas D own (McMaster University) as part of BIRS workshop: Canadian Queueing Theo rists and Practitioners Conference\n\n\nAbstract\nWhen job sizes are known \, Shortest Remaining Processing Time (SRPT) is known to be an optimal (in a very strong sense) scheduling policy for a single server queue under ge neral assumptions on underlying random variables. However\, the performanc e of SRPT is known not to be robust to errors in processing time estimates . For a popular error model\, we characterize the optimal policy using a G ittins Index approach and discuss its properties. The implementability of the policy is studied\, with the structure of the optimal policy guiding h euristic policies that appear to perform well. Time permitting\, issues fo r multiple server queues will be highlighted.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Peter Taylor (University of Melbourne) DTSTART:20200821T220000Z DTEND:20200821T230000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/9 DESCRIPTION:Title: Admission Policies for Complex Resource Allocation Problems\nby Peter Taylor (University of Melbourne) as part of BIRS workshop: Can adian Queueing Theorists and Practitioners Conference\n\n\nAbstract\nThere are many applications where users of different types arrive to a finite s et of resources and request temporary use of subsets of these resources. T he manager of the resources is entitled to charge for their use and might incur some costs in making them available.\n\nIn this context\, the manage r has an admission control problem. Given the current state of allocation\ , can they admit a user of a particular type? If they can\, should they\, or wait for a more lucrative user to arrive in the future? In the situatio n where a user is indifferent between different sets of resources\, which ones should they choose?\n\nIn this talk I shall discuss my long history o f engaging with different versions of this problem\, culminating with some current work with Jing Fu and Bill Moran in which we are looking at a res tless multi-armed bandit formulation.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Winfried Grassmann (University of Saskatchewan) DTSTART:20200822T143000Z DTEND:20200822T153000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/10 DESCRIPTION:Title: Queueing Theory in a World where most Queueing Problems are S olved by Simulation\nby Winfried Grassmann (University of Saskatchewan ) as part of BIRS workshop: Canadian Queueing Theorists and Practitioners Conference\n\n\nAbstract\nMonte Carlo simulation is one of the most succes sful techniques\, not only in operations research and performance evaluati on\, but in science in general. One reason for this extraordinary success is its flexibility. In contrast\, most queueing models are rather speciali zed. In this talk\, we suggest methods to make queueing theory more flexib le. In particular\, we suggest an event-based approach\, which provides gr eat flexibility for the modeller. We also show how to convert such event-b ased models into Markov chains\, which can then be solved by classical num erical methods. The suggested method is particularly suited for small mode ls\, where its execution times are much lower than Monte-Carlo simulation. For larger problems\, the curse of dimensionality takes over\, and the ex ecution times based on classical numerical methods increase exponentially. This means that for complex models\, simulation finds numerical solutions with less computer time than classical numerical methods.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Javad Tavakoli (University of British Columbia - Okanagan) DTSTART:20200822T153000Z DTEND:20200822T160000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/11 DESCRIPTION:Title: The Distribution of the Line Length in a GI/G/1 Queue Using D istribution Little Laws and Roots Methods\nby Javad Tavakoli (Universi ty of British Columbia - Okanagan) as part of BIRS workshop: Canadian Queu eing Theorists and Practitioners Conference\n\n\nAbstract\nIn this talk\, we provide a method\, called L\, based on distributional law of Little (DL L) to determine the equilibrium distribution of the number of elements in a discrete-time GI/G/1 queueing system. We also clarify a number of issues \, and provide a number of new results. We assume that the inter-arrival t imes range from 1 to g+1 and the service times from 1 to h+1. The majority of authors have formulated the system in question as a quasi birth and de ath process\, which can be solved by the matrix iterative methods pioneere d by Neuts\, methods that are cubic in the number of phases\, and in fact\ , if g=h\, all matrix analytic methods we found in literature are cubic in g\, or worse. In contrast\, our method L\, which finds the distribution o f the number of elements in the system in quadratic time. This implies tha t for large enough g and h\, our algorithm will outperform all cubic algor ithms\, a claim verified by numerical tests. In particular\, for realistic values g and h\, algorithm L is more than 50 times faster than the differ ent algorithms based on matrix analytic methods we found in literature.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Ruichao Jiang (UBC Okanagan) DTSTART:20200822T160000Z DTEND:20200822T163000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/12 DESCRIPTION:Title: An upper bound for the Galois group of weight walks with rati onal coefficients in the quarter plane\nby Ruichao Jiang (UBC Okanagan ) as part of BIRS workshop: Canadian Queueing Theorists and Practitioners Conference\n\n\nAbstract\nUsing Mazur’s theorem on torsions of elliptic curves\, an upper bound 24 for the order of the finite Galois group H asso ciated with weighted walks in the quarter plane Z2+ is obtained. The expli cit criterion of H having order 4 or 6 is given by geometric argument. Usi ng division polynomial\, a recursive criterion for H having order 4m or 4m + 2 is also obtained and explicit criterion for H having order 8 is given .\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Vera Tilson (University of Rochester) DTSTART:20200822T170000Z DTEND:20200822T173000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/13 DESCRIPTION:Title: Models of the Impact of Triage Nurse Standing Orders on Emerg ency Department Length of Stay\nby Vera Tilson (University of Rocheste r) as part of BIRS workshop: Canadian Queueing Theorists and Practitioners Conference\n\n\nAbstract\nStanding orders allow triage nurses in emergenc y departments (EDs) to order tests for certain medical conditions before t he patient sees a physician\, which could reduce the patient’s ED length of stay (LOS). Several studies in the medical literature documented a dec rease in average ED LOS for a target patient population\, resulting from t he use of standing orders. We formulate models of the operational impact o f standing orders and test several policies for whether to order tests at triage for individual target patients\, as a function of ED congestion. We find that a threshold policy\, with a threshold whose value can be estima ted easily from model primitives\, performs well across a wide range of pa rameter values. We demonstrate potential unintended consequences of the us e of standing orders\, including over testing and spillover effects on non -target patients.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/13/ END:VEVENT BEGIN:VEVENT SUMMARY:George Zhang (Simon Fraser University) DTSTART:20200822T173000Z DTEND:20200822T180000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/14 DESCRIPTION:Title: Performance Analysis of a Markovian Queue with Service Rate a nd Customers' Joining Decisions\nby George Zhang (Simon Fraser Univers ity) as part of BIRS workshop: Canadian Queueing Theorists and Practitione rs Conference\n\n\nAbstract\nWe consider the customers' equilibrium strate gy and socially optimal strategy in a single server Markovian queueing sys tem with changeable service rates controlled by a threshold. When a custom er arrives at an empty system\, he is served by the server at a lower serv ice rate. When the queue length reaches the threshold\, customers are serv ed at a high service rate. The optimal joining strategies of customers are studied under two information scenarios. The first scenario\, where the s erver' state and the queue length are observable\, is called a fully obser vable case. The second scenario\, where the system state is not observable \, is called an unobservable case. We analyze the steady-state distributio n and performance measures of the system\, and derive the equilibrium stra tegy. Finally\, we compare the equilibrium strategy with socially optimal strategy via numerical examples.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Na Li (Mcmaster University) DTSTART:20200822T180000Z DTEND:20200822T183000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/15 DESCRIPTION:Title: A decision integration strategy for short-term demand forecas ting and ordering for red blood cell components\nby Na Li (Mcmaster Un iversity) as part of BIRS workshop: Canadian Queueing Theorists and Practi tioners Conference\n\n\nAbstract\nBlood transfusion is one of the most cru cial and commonly administered therapeutics worldwide. The need for more a ccurate and efficient ways to manage blood demand and supply is an increas ing concern in many healthcare systems. Building a technology-based\, robu st blood demand and supply chain that can achieve the goals of reducing or dering frequency\, inventory level\, wastage and shortage\, while maintain ing the safety of blood usage\, is essential in modern healthcare systems. In this study\, we summarize the key challenges in current demand and sup ply management for red blood cells (RBCs). We combine ideas from statistic al time series modeling\, machine learning\, and operations research in de veloping an ordering decision strategy for RBCs integrating a hybrid deman d forecasting model using clinical predictors\, and a data-driven multi-pe riod inventory problem considering inventory and reorder constraints. We h ave applied the integrated ordering strategy to the blood inventory manage ment system in Hamilton\, Ontario using a large clinical database from 200 8 to 2018. The proposed hybrid demand forecasting model provides robust an d accurate predictions\, and identifies important clinical predictors for short-term RBC demand forecasting. Compared with the actual historical inv entory levels\, ordering decisions\, and wastage due to expiration\, our i ntegrated ordering strategy reduces the inventory level by approximately 4 0% and decreases the ordering frequency by approximately 60%\, with low in cidence of shortages and wastage due to expiration. If implemented success fully\, our proposed strategy can achieve significant cost savings for hea lthcare systems and blood suppliers. The proposed ordering strategy is gen eralizable to other blood products or even other perishable products.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Katsunobu Sasanuma (Stony Brook University) DTSTART:20200822T183000Z DTEND:20200822T190000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/16 DESCRIPTION:Title: Queueing and Markov chain decomposition method to analyze Mar kov-modulated Markov chains\nby Katsunobu Sasanuma (Stony Brook Univer sity) as part of BIRS workshop: Canadian Queueing Theorists and Practition ers Conference\n\n\nAbstract\nWe present a Queueing and Markov chain decom position method based on the total expectation theorem. Our decomposition method requires partial flow to be conserved\, which we call a termination scheme. This scheme is useful when deriving analytical formulas for compl ex queueing systems. As an example\, we apply our method to derive an exac t set of stationary equations for the probability generating functions of decomposed chains of Markov-modulated continuous-time Markov chains.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Ahmed Sid Ali (Carleton University) DTSTART:20200822T190000Z DTEND:20200822T193000Z DTSTAMP:20260404T042038Z UID:BIRS_20w2253/17 DESCRIPTION:Title: Fluid model for multiple TCP and UDP connections through a ne twork of queues in a random environment\nby Ahmed Sid Ali (Carleton Un iversity) as part of BIRS workshop: Canadian Queueing Theorists and Practi tioners Conference\n\n\nAbstract\nThe Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite and major inte rnet applications rely on it. The TCP protocol provides reliability\, flow control and congestion control. Alongside the TCP\, the User Datagram Pro tocol (UDP) is another transport protocol which\, in contrast to TCP\, is a simplified request-response protocol that does not have any connection s etup time and does not provide any flow\, congestion or error controls. We consider in this presentation a fluid model for multiple TCP and UDP conn ections interacting through a network of queues. We suppose that the conne ctions are randomly routed according to a dynamical routing table protocol which takes into account the topology of the network and adapts the routi ng dynamically. Our model extends the multi-class model studied in Graham et al (2009). The dynamic of the TCP flows follows the additive increase/m ultiplicative-decrease (AIMD) protocol and is represented by a stochastic differential equation w.r.t. a Poisson random measure and the UDP flows ar e represented by simple point processes. Using an adequate scaling\, a mea n-field result is proved where\, as the number of connections goes to infi nity\, the behaviour of the different connections can be represented by th e solution of an original nonlinear stochastic differential equation. The existence and uniqueness of the solution of this equation are derived. Mor eover\, we discuss some open problems and possible extensions. This talk i s based on a current ongoing joint work with Donald A.Dawson and Yiqiang Q .Zhao.\n LOCATION:https://stable.researchseminars.org/talk/BIRS_20w2253/17/ END:VEVENT END:VCALENDAR