COST ANALYSIS OF THE R-UNRELIABLE-UNLOADER QUEUEING SYSTEM

2008 ◽  
Vol 25 (01) ◽  
pp. 57-73
Author(s):  
KUO-HSIUNG WANG ◽  
CHUN-CHIN OH ◽  
JAU-CHUAN KE

This paper analyzes the unloader queueing model in which N identical trailers are unloaded by R unreliable unloaders. Steady-state analytic solutions are obtained with the assumptions that trip times, unloading times, finishing times, breakdown times, and repair times have exponential distributions. A cost model is developed to determine the optimal values of the number of unloaders and the finishing rate simultaneously, in order to minimize the expected cost per unit time. Numerical results are provided in which several steady-state characteristics of the system are calculated based on assumed numerical values given to the system parameters and the cost elements. Sensitivity analysis is also studied.

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 618b-618
Author(s):  
Paul N. Walker ◽  
Joan P. Harris ◽  
Loren D. Gautz

Four engineering studies on optimization of sugarcane micropropagation are summarized. The optimum environmental conditions based on the cost of production were found to be with two medium changes per multiplication period, 6 initial shoots per vessel and a photosynthetic photon flux of 200 μmol/m2s even though greater production was obtained for more light, fewer shoots per vessel and more medium changes. A cost model for comparing production treatments under steady state production and a linear programming model for unsteady state production are discussed. Preliminary results on mechanization of the transfer process are also presented.


2021 ◽  
Vol 31 (3) ◽  
Author(s):  
Pallabi Medhi

This paper presents stochastic modelling of a single server, finite buffer Markovian queuing system with discouraged arrivals, balking, reneging, and retention of reneged customers. Markov process is used to derive the steady-state solution of the model. Closed form expressions using probability generating functions (PGFs) are derived and presented for both classical and novel performance measures. In addition, a sensitivity analysis is carried out to study the effect of the system parameters on performance measures. A numerical problem is also presented to demonstrate the derived results and some design aspects.


2009 ◽  
Vol 26 (01) ◽  
pp. 85-113 ◽  
Author(s):  
SRINIVAS R. CHAKRAVARTHY

We study a MAP/M/c queueing system in which a group of servers take a simultaneous phase type vacation. The queueing model is studied as a QBD process. The steady-state analysis of the model including the waiting time distribution is presented. Interesting numerical results are discussed.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4224-4224
Author(s):  
Charles Edward Mahan ◽  
Matt Borrego ◽  
Alex C Spyropoulos

Abstract Abstract 4224 Introduction. Venous thromboembolism (VTE) is comprised of deep vein thrombosis (DVT) and pulmonary embolism (PE). VTE is a common cause of serious morbidity and mortality associated predominantly with hospitalization. The concept of “preventable” DVT has recently emerged in the medical literature. VTE remains the number one cause of preventable death in hospitalized patients. To date, VTE costs at a United States (US) national level for total costs, hospital-acquired costs, and “preventable” hospital-acquired costs have not yet been well-defined. Recently, investigators have defined US annual total, hospital-acquired, and preventable DVT costs ranged from $7.5 to $39.5 billion, $5 to $26.5 billion, and $2.5 to $19.5 billion, respectively, in 2010 US dollars. When a multi-way sensitivity analysis was applied, taking into consideration higher incidence rates and costs, annual US total, hospital-acquired, and “preventable” DVT costs ranged from $9.8 to $52 billion, $6.8 to $36 billion, and $3.4 to $27 billion, respectively. In addition, it was estimated that the US annual prophylaxis cost of at-risk patients is less than $600 million per year. PE costs have not yet been defined within the US. Defining PE costs would allow for definition of total US VTE costs on an annual basis. Methods. The authors undertook a thorough research review to identify morbidities, incident rates of morbidities, costs of morbidities and incidences of death associated with PE. Identified references were then hand-searched to ensure no pertinent publications had been overlooked. A decision tree and cost model were developed to estimate the United States healthcare costs for PE, total hospital-acquired PE, and total “preventable” PE. The decision tree contains probability information on: PE's that are hospital-acquired or community-acquired; fatal vs. non-fatal; readmissions; VTE recurrence; minor bleed; major bleed; heparin induced thrombocytopenia; chronic thromboembolic pulmonary hypertension; and resolution of symptoms. Based on the decision tree, a cost model with calculations performed via Microsoft Office Excel was developed. The cost model contains all potential outcomes, representing all branches, to reflect all possible outcomes for a PE patient. The product of each outcome's probabilities and costs yields the average cost of a patient going down that respective path of the PE decision tree. Similarly, each branch contains a sum that reflects the average cost of a patient in that branch. Results. Preliminary estimates of US annual direct total, hospital-acquired, and preventable PE costs are likely to range (at a minimum) from $5 to $27 billion, $2.5 to $18 billion, and $2.1 to $15.4 billion, respectively, in 2010 US dollars. Indirect costs, primarily from death due to PE, are estimated to be a minimum of $19.5 billion per year with approximately $11 billion per year of this being “preventable.” A multi-way sensitivity analysis will be applied which will take into consideration higher incidence rates and costs. Final results of the cost analysis, with the multi-way sensitivity analysis will be presented. Preliminary estimates suggest minimum total annualized, direct, VTE costs of approximately $12.5 to $66 billion per year with a minimum of $4.6 to $34.9 billion per year being “preventable.” When factoring in the indirect costs of $11 billion per year, minimum, “preventable” VTE costs within the US appear to range from $15.6 to $45.9 billion per year. Final results of the cost analysis with the multi-way sensitivity analysis will be presented. Conclusions. Considerable savings and reduced morbidity and mortality could be realized if improved prevention rates were achieved and systems were implemented throughout the US. To date, US VTE costs have been underestimated. The DVT and PE cost models may be applied to estimate costs in the European Union and other countries. VTE prophylaxis is cost effective and may be a good target for healthcare savings with healthcare reform on the horizon. Mandating VTE quality measures, such as those from the Joint Commission and National Quality Forum, would expedite reducing health care costs and reduce unnecessary morbidity and mortality. Disclosures: No relevant conflicts of interest to declare.


2019 ◽  
Vol 25 (2) ◽  
pp. 147-154
Author(s):  
Hayette Braham ◽  
Louiza Berdjoudj ◽  
Mohamed Boualem ◽  
Nadji Rahmania

Abstract The stationary distribution is the key of any queueing system; its determination is sufficient to infer the corresponding characteristics. This paper deals with the {\mathrm{Er}/M/1} queue. Bayesian inference is developed to estimate the system parameters, specially the root of the relative equation which allows the determination of the stationary distribution. A numerical study is performed with MCMC methods to support the results, and a comparison with another existing method in the literature (moments method) is provided.


BMJ Open ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. e038867 ◽  
Author(s):  
Wenxiu Xin ◽  
Haiying Ding ◽  
Qilu Fang ◽  
Xiaowei Zheng ◽  
Yinghui Tong ◽  
...  

BackgroundPembrolizumab was recently demonstrated to have survival benefit in patients with recurrent or metastatic head and neck squamous cell carcinoma (r/mHNSCC). However, the cost-effectiveness of pembrolizumab versus chemotherapy in China remains uncertain.ObjectiveThis analysis aimed to describe the cost-effectiveness of pembrolizumab versus standard-of-care (SOC) therapy in r/mHNSCC in China.DesignA Markov model consisting of three health states (stable, progressive and dead) was developed to compare the cost and effectiveness of pembrolizumab with SOC in platinum-resistant r/mHNSCC. Model inputs for transition probabilities and toxicity were collected from the KEYNOTE-040 trial, while health utilities were estimated from a literature review. Cost data were acquired for the payer’s perspective in China. Costs and outcomes were discounted at an annual rate of 3.0%. Sensitivity analyses were conducted to test the uncertainties surrounding model parameters.Outcome measuresThe primary outcome was incremental cost-effectiveness ratios (ICERs), which were calculated as the cost per quality-adjusted life years (QALYs).ResultsThe total mean cost of pembrolizumab and SOC was US$45 861 and US$41 950, respectively. As for effectiveness, pembrolizumab yielded 0.31 QALYs compared with 0.25 QALYs for SOC therapy. The ICER for pembrolizumab versus SOC was US$65 186/QALY, which was higher than the willingness-to-pay threshold (WTP) of US$28 130/QALY in China. The univariate sensitivity analysis indicated that utility values for progressive state, probability from stable to progressive in the SOC group, as well as cost of pembrolizumab were the three most influential variables on ICER. The probabilistic sensitivity analysis demonstrated that standard therapy was more likely to be cost-effective compared with pembrolizumab at a WTP value of US$28 130/QALY. Results were robust across both univariate analysis and probabilistic sensitivity analysis.ConclusionsPembrolizumab is not likely to be a cost-effective strategy compared with SOC therapy in patients with platinum-resistant r/mHNSCC in China.Trial registration numberNCT02252042; Post-results.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Neide Canana

Abstract Background It is frequently said that funding is essential to ensure optimal results from a malaria intervention control. However, in recent years, the capacity of the government of Mozambique to sustain the operational cost of indoor residual spraying (IRS) is facing numerous challenges due to restrictions of the Official Development Assistance. The purpose of the study was to estimate the cost of IRS operationalization in two districts of Maputo Province (Matutuíne and Namaacha) in Mozambique. The evidence produced in this study intends to provide decision-makers with insight into where they need to pay close attention in future planning in order to operationalize IRS with the existent budget in the actual context of budget restrictions. Methods Cost information was collected retrospectively from the provider perspective, and both economic and financial costs were calculated. A “one-way” deterministic sensitivity analysis was performed. Results The average economic costs totaled US$117,351.34, with an average economic cost per household sprayed of US$16.35, and an average economic cost per person protected of US$4.09. The average financial cost totaled US$69,174.83, with an average financial cost per household sprayed and per person protected of US$9.84 and US$2.46, respectively. Vehicle, salary, and insecticide costs were the greatest contributors to overall cost in the economic and financial analysis, corresponding to 52%, 17%, and 13% in the economic analysis and 21%, 27%, and 22% in the financial analysis, respectively. The sensitivity analysis was adapted to a range of ± (above and under) 25% change. There was an approximate change of 14% in the average economic cost when vehicle costs were decreased by 25%. In the financial analysis, the average financial cost was lowered by 7% when salary costs were decreased by 25%. Conclusions Altogether, the current cost analysis provides an impetus for the consideration of targeted IRS operationalization within the available governmental budget, by using locally-available human resources as spray operators to decrease costs and having IRS rounds be correctly timed to coincide with the build-up of vector populations.


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