scholarly journals SCHEDULING IMPATIENT JOBS IN A CLEARING SYSTEM WITH INSIGHTS ON PATIENT TRIAGE IN MASS CASUALTY INCIDENTS

2008 ◽  
Vol 22 (3) ◽  
pp. 301-332 ◽  
Author(s):  
Nilay Tanik Argon ◽  
Serhan Ziya ◽  
Rhonda Righter
Keyword(s):  
Service Time ◽  
Optimal Policy ◽  
Numerical Study ◽  
Complex Structure ◽  
Mass Casualty ◽  
Single Server ◽  
Worst Case ◽  
State Dependent ◽  
Clearing System ◽  
Mass Casualty Event

Motivated by the patient triage problem in emergency response, we consider a single-server clearing system in which jobs might abandon the system if they are not taken into service within their “lifetime.” In this system, jobs are characterized by their lifetime and service time distributions. Our objective is to dynamically determine the optimal or near-optimal order of service for jobs so as to minimize the total number of abandonments. We first show that if the jobs can be ordered in such a way that the job with the shortest lifetime (in the sense of hazard rate ordering) also has the shortest service time (in the sense of likelihood ratio ordering), then the optimal policy gives the highest priority to this “time-critical” job independently of the system state. For the case in which the jobs with shorter lifetimes have longer service times, we observed that the optimal policy generally has a complex structure that might depend on the type and number of jobs available. For this case, we provide partial characterizations of the optimal policy and obtain sufficient conditions under which a state-independent policy is optimal. Furthermore, we develop two state-dependent heuristic policies, and by means of a numerical study, we show that these heuristics perform well, especially when jobs abandon the system at a relatively faster rate when compared to service rates. Based on our analytical and numerical results, we develop several insights on patient triage in the immediate aftermath of a mass casualty event. For example, we conclude that in a worst-case scenario, where medical resources are overwhelmed with a large number of casualties who need immediate attention, it is crucial to implement state-dependent policies such as the heuristic policies proposed in this article.

scholarly journals SCHEDULING IN A SINGLE-SERVER QUEUE WITH STATE-DEPENDENT SERVICE RATES

2019 ◽  
Vol 34 (4) ◽  
pp. 507-521
Author(s):  
Urtzi Ayesta ◽  
Balakrishna Prabhu ◽  
Rhonda Righter
Keyword(s):  
Optimal Policy ◽  
Arrival Rate ◽  
Complete Characterization ◽  
Single Server ◽  
Holding Costs ◽  
Release Times ◽  
State Dependent ◽  
Service Rates ◽  
Transient System ◽  
The Cost

We consider single-server scheduling to minimize holding costs where the capacity, or rate of service, depends on the number of jobs in the system, and job sizes become known upon arrival. In general, this is a hard problem, and counter-intuitive behavior can occur. For example, even with linear holding costs the optimal policy may be something other than SRPT or LRPT, it may idle, and it may depend on the arrival rate. We first establish an equivalence between our problem of deciding which jobs to serve when completed jobs immediately leave, and a problem in which we have the option to hold on to completed jobs and can choose when to release them, and in which we always serve jobs according to SRPT. We thus reduce the problem to determining the release times of completed jobs. For the clearing, or transient system, where all jobs are present at time 0, we give a complete characterization of the optimal policy and show that it is fully determined by the cost-to-capacity ratio. With arrivals, the problem is much more complicated, and we can obtain only partial results.

Assigning Priorities (or Not) in Service Systems with Nonlinear Waiting Costs

2021 ◽  
Author(s):  
Huiyin Ouyang ◽  
Nilay Taník Argon ◽  
Serhan Ziya
Keyword(s):  
Service Time ◽  
Queueing System ◽  
Numerical Study ◽  
Arrival Rate ◽  
The Other ◽  
Cost Functions ◽  
Single Server ◽  
Dominant Type ◽  
Fixed Priority ◽  
Poisson Arrivals

For a queueing system with multiple customer types differing in service-time distributions and waiting costs, it is well known that the cµ-rule is optimal if costs for waiting are incurred linearly with time. In this paper, we seek to identify policies that minimize the long-run average cost under nonlinear waiting cost functions within the set of fixed priority policies that only use the type identities of customers independently of the system state. For a single-server queueing system with Poisson arrivals and two or more customer types, we first show that some form of the cµ-rule holds with the caveat that the indices are complex, depending on the arrival rate, higher moments of service time, and proportions of customer types. Under quadratic cost functions, we provide a set of conditions that determine whether to give priority to one type over the other or not to give priority but serve them according to first-come, first-served (FCFS). These conditions lead to useful insights into when strict (and fixed) priority policies should be preferred over FCFS and when they should be avoided. For example, we find that, when traffic is heavy, service times are highly variable, and the customer types are not heterogenous, so then prioritizing one type over the other (especially a proportionally dominant type) would be worse than not assigning any priority. By means of a numerical study, we generate further insights into more specific conditions under which fixed priority policies can be considered as an alternative to FCFS. This paper was accepted by Baris Ata, stochastic models and simulation.

OPTIMAL CONTROL OF A MAKE-TO-STOCK SYSTEM WITH ADJUSTABLE SERVICE RATE

2006 ◽  
Vol 20 (4) ◽  
pp. 609-634 ◽  
Author(s):  
Maria E. Mayorga ◽  
Hyun-Soo Ahn ◽  
J. George Shanthikumar
Keyword(s):  
Optimal Policy ◽  
Numerical Study ◽  
Infinite Horizon ◽  
Service Rate ◽  
New Order ◽  
Single Server ◽  
Rationing Policy ◽  
Make To Stock ◽  
Infinite Horizon Problems ◽  
Horizon Problems

We consider a multiclass make-to-stock system served by a single server with adjustable capacity (service rate). At any point in time, the decision-maker must determine the capacity level, make a production decision (i.e., whether to produce an item to stock or to satisfy a backorder), and make a rationing decision (i.e., whether to satisfy a new order from stock or place it on backorder). In this article we characterize the structure of optimal capacity adjustment, production, and stock rationing policy for both finite- and infinite-horizon problems. We show that an optimal policy is monotone in current inventory and backorder levels, and we characterize its properties. In a numerical study we compare the optimal policy with heuristic policies and show that the savings from using an optimal policy can be significant.

State-dependent signalling in queueing networks

1994 ◽  
Vol 26 (02) ◽  
pp. 436-455 ◽  
Author(s):  
W. Henderson ◽  
B. S. Northcote ◽  
P. G. Taylor
Keyword(s):  
Queueing Networks ◽  
State Dependence ◽  
Product Form ◽  
Batch Size ◽  
Single Server ◽  
Negative Customers ◽  
Affect Control ◽  
State Dependent ◽  
Special Cases ◽  
Equilibrium Distributions

It has recently been shown that networks of queues with state-dependent movement of negative customers, and with state-independent triggering of customer movement have product-form equilibrium distributions. Triggers and negative customers are entities which, when arriving to a queue, force a single customer to be routed through the network or leave the network respectively. They are ‘signals' which affect/control network behaviour. The provision of state-dependent intensities introduces queues other than single-server queues into the network. This paper considers networks with state-dependent intensities in which signals can be either a trigger or a batch of negative customers (the batch size being determined by an arbitrary probability distribution). It is shown that such networks still have a product-form equilibrium distribution. Natural methods for state space truncation and for the inclusion of multiple customer types in the network can be viewed as special cases of this state dependence. A further generalisation allows for the possibility of signals building up at nodes.

Non-Pediatric Nurses’ Willingness to Provide Care to Pediatric Patients during a Disaster: An Assessment of Pediatric Surge Capacity in Four Midwestern Hospitals

2021 ◽  
pp. 1-6
Author(s):  
Terri Rebmann ◽  
Rachel L. Charney ◽  
Rebecca L. Eschmann ◽  
M. Colleen Fitzpatrick
Keyword(s):  
Pediatric Patients ◽  
Response Rate ◽  
Mass Casualty ◽  
Pediatric Care ◽  
Pediatric Nurses ◽  
Surge Capacity ◽  
Factors Associated ◽  
Pediatric Hospitals ◽  
Survey Response Rate ◽  
Mass Casualty Event

Abstract Objective: To assess non-pediatric nurses’ willingness to provide care to pediatric patients during a mass casualty event (MCE). Methods: Nurses from 4 non-pediatric hospitals in a major metropolitan Midwestern region were surveyed in the fall of 2018. Participants were asked about their willingness to provide MCE pediatric care. Hierarchical logistical regression was used to describe factors associated with nurses’ willingness to provide MCE pediatric care. Results: In total, 313 nurses were approached and 289 completed a survey (response rate = 92%). A quarter (25.3%, n = 73) would be willing to provide MCE care to a child of any age; 12% (n = 35) would provide care only to newborns in the labor and delivery area, and 16.6% (n = 48) would only provide care to adults. Predictors of willingness to provide care to a patient of any age during an MCE included providing care to the youngest-age children during routine duties, reporting confidence in calculating doses and administering pediatric medications, working in the emergency department, being currently or previously certified in PALS, and having access to pediatric-sized equipment in the unit or hospital. Conclusion: Pediatric surge capacity is lacking among nurses. Increasing nurses’ pediatric care self-efficacy could improve pediatric surge capacity and minimize morbidity and mortality during MCEs.

Postexposure Interventions to Prevent Infection With HBV, HCV, or HIV, and Tetanus in People Wounded During Bombings and Other Mass Casualty Events—United States, 2008: Recommendations of the Centers for Disease Control and Prevention and Disaster Medicine and Public Health Preparedness

2008 ◽  
Vol 2 (3) ◽  
pp. 150-165 ◽  
Author(s):  
Louisa E. Chapman ◽  
Ernest E. Sullivent ◽  
Lisa A. Grohskopf ◽  
Elise M. Beltrami ◽  
Joseph F. Perz ◽  
...  
Keyword(s):  
Public Health ◽  
Disease Control ◽  
Emergency Response ◽  
Mass Casualty ◽  
Acute Injury ◽  
Mass Casualties ◽  
Public Health Preparedness ◽  
Mass Casualty Event ◽  
Public Health Officials ◽  
Centers For Disease Control

ABSTRACTPeople wounded during bombings or other events resulting in mass casualties or in conjunction with the resulting emergency response may be exposed to blood, body fluids, or tissue from other injured people and thus be at risk for bloodborne infections such as hepatitis B virus, hepatitis C virus, human immunodeficiency virus, or tetanus. This report adapts existing general recommendations on the use of immunization and postexposure prophylaxis for tetanus and for occupational and nonoccupational exposures to bloodborne pathogens to the specific situation of a mass casualty event. Decisions regarding the implementation of prophylaxis are complex, and drawing parallels from existing guidelines is difficult. For any prophylactic intervention to be implemented effectively, guidance must be simple, straightforward, and logistically undemanding. Critical review during development of this guidance was provided by representatives of the National Association of County and City Health Officials, the Council of State and Territorial Epidemiologists, and representatives of the acute injury care, trauma, and emergency response medical communities participating in the Centers for Disease Control and Prevention’s Terrorism Injuries: Information, Dissemination and Exchange project. The recommendations contained in this report represent the consensus of US federal public health officials and reflect the experience and input of public health officials at all levels of government and the acute injury response community. (Disaster Med Public Health Preparedness. 2008;2:150–165)

scholarly journals Stochastic Approximations and Monotonicity of a Single Server Feedback Retrial Queue

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Mohamed Boualem ◽  
Natalia Djellab ◽  
Djamil Aïssani
Keyword(s):  
Markov Chains ◽  
Service Time ◽  
Retrial Queue ◽  
Stochastic Ordering ◽  
Stochastic Comparison ◽  
Single Server ◽  
Stochastic Approximations ◽  
Bernoulli Feedback ◽  
Monotonicity Results

This paper focuses on stochastic comparison of the Markov chains to derive some qualitative approximations for anM/G/1retrial queue with a Bernoulli feedback. The main objective is to use stochastic ordering techniques to establish various monotonicity results with respect to arrival rates, service time distributions, and retrial parameters.

On queueing systems by retrials

1983 ◽  
Vol 20 (02) ◽  
pp. 380-389 ◽  
Author(s):  
Vidyadhar G. Kulkarni
Keyword(s):  
General Result ◽  
Service Time ◽  
Queueing Systems ◽  
Single Server ◽  
Expected Number ◽  
Waiting Room ◽  
Second Moments ◽  
Different Types ◽  
General Distributions ◽  
Arbitrary Service Time

A general result for queueing systems with retrials is presented. This result relates the expected total number of retrials conducted by an arbitrary customer to the expected total number of retrials that take place during an arbitrary service time. This result is used in the analysis of a special system where two types of customer arrive in an independent Poisson fashion at a single-server service station with no waiting room. The service times of the two types of customer have independent general distributions with finite second moments. When the incoming customer finds the server busy he immediately leaves and tries his luck again after an exponential amount of time. The retrial rates are different for different types of customers. Expressions are derived for the expected number of retrial customers of each type.

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