Cost Effective Maintenance of Wind Turbines Using Finite State Markov Model

2015 ◽  
Vol 799-800 ◽  
pp. 1422-1426
Author(s):  
Lahcene Boukelkoul
Keyword(s):  
Markov Model ◽  
Optimal Solution ◽  
Minimum Cost ◽  
Cost Effective ◽  
Maintenance Cost ◽  
Cost Of Energy ◽  
Finite State ◽  
Evaluation Metric ◽  
Cost Parameters ◽  
The Cost

Nowadays the cost effectiveness concept becomes a decision-making and technology evaluation metric. The cost of energy metric accounts for the effect of reliability through levelized replacement cost and unscheduled maintenance cost parameters. One key of the proposed approach is the idea of maintaining the WTs which can be captured via use of a finite state Markov chain. Such a model can be embedded within a probabilistic operation and maintenance simulation reflecting the action to be done. In this paper a finite state Markov model is used for decision problems with number of determined periods (life cycle) to predict the cost according to the option of the maintenance adopted. The minimum cost is taken as the optimal solution.

scholarly journals Analysis and Optimization of a Novel Hexagonal Waveguide Concentrator for Solar Thermal Applications

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2146
Author(s):  
Karunesh Kant ◽  
Karthik Nithyanandam ◽  
Ranga Pitchumani
Keyword(s):  
Industrial Process ◽  
Cost Effective ◽  
Solar Irradiation ◽  
Maintenance Cost ◽  
Solar Concentrator ◽  
Thermal Desalination ◽  
Process Heat ◽  
Solar Thermal Applications ◽  
The Cost ◽  
Operation And Maintenance Cost

This paper analyzes a novel, cost-effective planar waveguide solar concentrator design that is inspired by cellular hexagonal structures in nature with the benefits of facile installation and low operation and maintenance cost. A coupled thermal and optical analysis of solar irradiation through an ideal hexagonal waveguide concentrator integrated with a linear receiver is presented, along with a cost analysis methodology, to establish the upper limit of performance. The techno-economic model, coupled with numerical optimization, is used to determine designs that maximized power density and minimized the cost of heat in the temperature range of 100–250 °C, which constitutes more than half of the industrial process heat demand. Depending on the incident solar irradiation and the application temperature, the cost of heat for the optimal design configuration ranged between 0.1–0.27 $/W and 0.075–0.18 $/W for waveguide made of ZK7 glass and polycarbonate, respectively. A techno-economic analysis showed the potential of the technology to achieve cost as low as 80 $/m2 and 61 $/m2 for waveguide made of ZK7 glass and polycarbonate material, respectively, which is less than half the cost of state-of-the-art parabolic trough concentrators. Overall, the hexagonal waveguide solar concentrator technology shows immense potential for decarbonizing the industrial process heat and thermal desalination sectors.

scholarly journals Managing cost uncertainties in transportation and assignment problems

1998 ◽  
Vol 2 (1) ◽  
pp. 65-104 ◽  
Author(s):  
V. Adlakha ◽  
H. Arsham
Keyword(s):  
Time Lag ◽  
Real Life ◽  
Optimal Solution ◽  
Global Market ◽  
Solution Algorithm ◽  
Assignment Problems ◽  
The Stability ◽  
Order Assignment ◽  
Cost Parameters ◽  
The Cost

In a fast changing global market, a manager is concerned with cost uncertainties of the cost matrix in transportation problems (TP) and assignment problems (AP).A time lag between the development and application of the model could cause cost parameters to assume different values when an optimal assignment is implemented. The manager might wish to determine the responsiveness of the current optimal solution to such uncertainties. A desirable tool is to construct a perturbation set (PS) of cost coeffcients which ensures the stability of an optimal solution under such uncertainties.The widely-used methods of solving the TP and AP are the stepping-stone (SS) method and the Hungarian method, respectively. Both methods fail to provide direct information to construct the needed PS. An added difficulty is that these problems might be highly pivotal degenerate. Therefore, the sensitivity results obtained via the available linear programming (LP) software might be misleading.We propose a unified pivotal solution algorithm for both TP and AP. The algorithm is free of pivotal degeneracy, which may cause cycling, and does not require any extra variables such as slack, surplus, or artificial variables used in dual and primal simplex. The algorithm permits higher-order assignment problems and side-constraints. Computational results comparing the proposed algorithm to the closely-related pivotal solution algorithm, the simplex, via the widely-used pack-age Lindo, are provided. The proposed algorithm has the advantage of being computationally practical, being easy to understand, and providing useful information for managers. The results empower the manager to assess and monitor various types of cost uncertainties encountered in real-life situations. Some illustrative numerical examples are also presented.

scholarly journals Techno-Economic Feasibility Study of Investigation of Renewable Energy System for Rural Electrification in South Algeria

2018 ◽  
Vol 8 (5) ◽  
pp. 3421-3426 ◽  
Author(s):  
F. Chermat ◽  
M. Khemliche ◽  
A. E. Badoud ◽  
S. Latreche
Keyword(s):  
Greenhouse Gas Emission ◽  
Electrical Energy ◽  
Energy System ◽  
Economic Feasibility ◽  
Maintenance Cost ◽  
Management Algorithm ◽  
Cost Of Energy ◽  
The Cost ◽  
Operation And Maintenance Cost ◽  
Different Sources

This work aims to consider the combination of different technologies regarding energy production and management with four possible configurations. We present an energy management algorithm to detect the best design and the best configuration from the combination of different sources. This combination allows us to produce the necessary electrical energy for supplying habitation without interruption. A comparative study is conducted among the different combinations on the basis of the cost of energy, diesel consumption, diesel price, capital cost, replacement cost, operation, and maintenance cost and greenhouse gas emission. Sensitivity analysis is also performed.

Cost Utility of Fractional Exhaled Nitric Oxide Monitoring for the Management of Children Asthma

2020 ◽  
Author(s):  
Jefferson Antonio Buendia ◽  
Rannery Acuña ◽  
carlos rodriguez
Keyword(s):  
Nitric Oxide ◽  
Markov Model ◽  
Standard Therapy ◽  
Asthma Management ◽  
Cost Effective ◽  
Cost Utility ◽  
Exhaled Nitric Oxide ◽  
Fractional Exhaled Nitric Oxide ◽  
Tertiary Center ◽  
The Cost

Abstract IntroductionFractional exhaled nitric oxide is a simple, non-invasive measurement of airway inflammation with minimal discomfort to the patient and with results available within a few minutes. This study aimed to evaluate the cost-effectiveness of asthma management using fractional exhaled nitric oxide monitoring in patients between 4 and 18 years of age.Methods A Markov model was used to estimate the cost-utility of asthma management using fractional exhaled nitric oxide monitoring versus asthma management without using fractional exhaled nitric oxide monitoring (standard therapy) in patients between 4 and 18 years of age. Cost data were obtained from a retrospective study on asthma from a tertiary center, in Medellin, Colombia, while probabilities of the Markov model and utilities were obtained from the systematic review of published randomized clinical trials. The analysis was carried out from a societal perspective.ResultsThe model showed that fractional exhaled nitric oxide monitoring was associated with a lower total cost than standard therapy (US $1,333 vs. US $1,452 average cost per patient) and higher QALYs (0.93 vs. 0.92 average per patient). The probability that fractional exhaled nitric oxide monitoring provides a more cost-effective use of resources compared with standard therapy exceeds 99% for all willingness-to-pay thresholds.Conclusion Asthma management using fractional exhaled nitric oxide monitoring was cost-effective for treating patients between 4 and 18 years of age with mild to moderate allergic asthma. Our study suggests evidence that could be used by decision-makers to improve clinical practice guidelines, but this should be replicated in different clinical settings.

Modeling the development of rail corrugation to schedule a more economical rail grinding

2019 ◽  
Vol 234 (4) ◽  
pp. 370-380 ◽  
Author(s):  
Hirofumi Tanaka ◽  
Masashi Miwa
Keyword(s):  
Surface Roughness ◽  
Growth Curves ◽  
Minimum Cost ◽  
Maintenance Cost ◽  
Rail Corrugation ◽  
Maintenance Schedule ◽  
Rail Grinding ◽  
Noise Vibration ◽  
Maintenance Schedules ◽  
The Cost

Rail corrugation should be managed appropriately, as it causes noise, vibration, and degradation of track components and materials. Generally, rail corrugation is managed with the removal of rail surface roughness by rail grinding. However, in many cases, rail corrugation will reoccur after the rail is ground, thereby making the management of the phenomenon difficult for railway operators. For the proper management of rail corrugation, it is necessary to understand the development of rail corrugation and model it mathematically. However, this effort has not been made in previous studies. This paper investigates an efficient method for scheduling a regular grinding maintenance to manage rail corrugation. Using regularly measured data about rail surface roughness on a commercial line, a mathematical model was developed to estimate the growth of rail corrugation. This model was utilized to estimate the effects of the remaining roughness after rail grinding on the maintenance cost and to optimize the maintenance schedule. First, it was confirmed that the development of rail surface roughness of rail corrugation can be expressed in three phases and can be modeled by fitting the functions of growth curves to measurements of rail surface roughness recorded over a long period. Next, the rail grinding strategy was examined by applying this model to realize both effective and economical strategies for the maintenance of rail corrugation. This study confirmed that maintenance costs can be reduced by rail grinding that removes almost all of rail corrugation. In the case of ballasted tracks, it has been found that the optimal grinding schedule can reduce the cost of rail grinding as well as the cost of tamping. These findings can be applied by railway operators tasked with managing maintenance schedules for railway lines at a minimum cost.

scholarly journals Replacement and Maintenance Decision Analysis for Hydraulic Machinery Facilities at Reservoirs under Imperfect Maintenance

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2507
Author(s):  
Sou-Sen Leu ◽  
Tao-Ming Ying
Keyword(s):  
Cost Effective ◽  
Maintenance Cost ◽  
Imperfect Maintenance ◽  
Term Operation ◽  
Engineering Economics ◽  
Hydraulic Machinery ◽  
Effective Manner ◽  
The Cost ◽  
Replacement Time

After the long-term operation of reservoir facilities, they will become nonoperational due to the material deterioration and the performance degradation. One of crucial decisions is to determine the maintenance or replacement of the facilities in a cost-effective manner. Conventional replacement models seldom consider the maintenance effect. The facilities after maintenance are generally not as good as new, but are relatively restored. The target of this study is to establish a replacement decision model of the reservoir facilities under imperfect maintenance. By combining the theories of reliability analysis, imperfect maintenance, and engineering economics, the best timing of replacement that achieves cost-effectiveness is analyzed and proposed. Lastly, based on the design of experiments (DOE) and simulation, the regression curve chart for the economical replacement decision is established. Once the failure rate, the age of recovery after maintenance, and the ratio of maintenance cost to replacement cost are estimated based on historical data, the cost-effective replacement time of hydraulic machinery facilities will be efficiently determined.

THE PRICE OF NASH EQUILIBRIA IN MULTICAST TRANSMISSION GAMES

2010 ◽  
Vol 11 (03n04) ◽  
pp. 97-120 ◽  
Author(s):  
VITTORIO BILÒ
Keyword(s):  
Nash Equilibrium ◽  
Cost Sharing ◽  
Price Of Anarchy ◽  
Optimal Solution ◽  
Minimum Cost ◽  
Price Of Stability ◽  
Common Source ◽  
Cost Share ◽  
Worst Case ◽  
The Cost

We consider the problem of sharing the cost of multicast transmissions in non-cooperative undirected networks where a set of receivers R wants to be connected to a common source s. The set of choices available to each receiver r ∈ R is represented by the set of all (s, r)-paths in the network. Given the choices performed by all the receivers, a public known cost sharing method determines the cost share to be charged to each of them. Receivers are selfish agents aiming to obtain the transmission at the minimum cost share and their interactions create a non-cooperative game. Devising cost sharing methods yielding games whose price of anarchy (price of stability), defined as the worst-case (best-case) ratio between the cost of a Nash equilibrium and that of an optimal solution, is not too high is thus of fundamental importance in non-cooperative network design. Moreover, since cost sharing games naturally arise in socio-economical contests, it is convenient for a cost sharing method to meet some constraining properties. In this paper, we first define several such properties and analyze their impact on the prices of anarchy and stability. We also reconsider all the methods known so far by classifying them according to which properties they satisfy and giving the first non-trivial lower bounds on their price of stability. Finally, we propose a new method, namely the free-riders method, which admits a polynomial time algorithm for computing a pure Nash equilibrium whose cost is at most twice the optimal one. Some of the ideas characterizing our approach have been independently proposed in Ref. 10.

A Multiple Level of Detail Approach to the Tactical Movement Problem

2012 ◽  
Vol 6 (6) ◽  
pp. 749-756 ◽  
Author(s):  
Peter Beasley ◽  
◽  
P. Ross McAree
Keyword(s):  
Optimal Path ◽  
Optimal Solution ◽  
Cost Effective ◽  
Multiple Level ◽  
Practical Application ◽  
Robotic Excavator ◽  
The World ◽  
The Cost ◽  
Robotic Agent ◽  
Movement Problem

The tactical movement problemis considered to be one in which a robotic agent is required to move around its world to complete a task. This agent has manipulation abilities which allow it to perform work on its local surroundings. The coupled optimisation of the agent movements and manipulations is thus of key importance to minimise the cost of completing the task. The driving practical application in this paper is one of cost effective excavation in a mining environment. The agent is a mining shovel and it has the ability to manipulate the world through excavation actions. The problem becomes one of determining the optimal path that the shovel should take and the dig operations that should be completed at each point along the path. An initial solution is presented to automatically generate an optimized dig plan for a large robotic excavator. A wavelet based detail reduction approach is used which allows a near optimal solution of the problem to be generated in practically useful timeframes.

A SIMPLE SOLUTION METHOD FOR THE FINITE HORIZON EOQ MODEL FOR DETERIORATING ITEMS WITH COST CHANGES

2011 ◽  
Vol 28 (06) ◽  
pp. 689-704 ◽  
Author(s):  
HORNG-JINH CHANG ◽  
WEN-FENG LIN
Keyword(s):  
Closed Form Solution ◽  
Minimum Cost ◽  
Form Solution ◽  
Inventory System ◽  
Finite Horizon ◽  
Eoq Model ◽  
Ordering Policy ◽  
Optimal Ordering Policy ◽  
Cost Parameters ◽  
The Cost

In this article, we generalize Lev and Weiss's (1990) finite horizon economic order quantity (EOQ) model with cost change to the inventory system with deterioration. Supplier announces some or all of cost parameters may change after a decided time. Depending on whether the inventory is depleted at the time of the last opportunity to purchase before some or all of the cost parameters may change, there are two types of inventory models to be discussed. The main objective of this paper is to identify the optimal ordering policy of the inventory system by comparing the minimum cost of the two types of models. We suggest a finite horizon EOQ model to combine the above two types and propose a theorem that can quickly identify the optimal policy of the suggested model. In considering temporary price discount problem and discrete-time EOQ problem, in general, there are integer operators in mathematical models, but our approach offers a closed-form solution to these kinds of problems. Numerical examples are presented to demonstrate the results of the proposed properties and theorem.

scholarly journals Cost-Effectiveness Analysis of Direct Oral Anticoagulants Versus Vitamin K Antagonists for Venous Thromboembolism in China

2021 ◽  
Vol 12 ◽  
Author(s):  
Ke-Xin Sun ◽  
Bin Cui ◽  
Shan-Shan Cao ◽  
Qi-Xiang Huang ◽  
Ru-Yi Xia ◽  
...  
Keyword(s):  
Decision Making ◽  
Sensitivity Analysis ◽  
Cost Effectiveness ◽  
Markov Model ◽  
Clinical Decision Making ◽  
Cost Effective ◽  
Clinical Decision ◽  
Base Case ◽  
Effectiveness Analysis ◽  
The Cost

Background: The drug therapy of venous thromboembolism (VTE) presents a significant economic burden to the health-care system in low- and middle-income countries. To understand which anticoagulation therapy is most cost-effective for clinical decision-making , the cost-effectiveness of apixaban (API) versus rivaroxaban (RIV), dabigatran (DAB), and low molecular weight heparin (LMWH), followed by vitamin K antagonist (VKA), in the treatment of VTE in China was assessed.Methods: To access the quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs), a long-term cost-effectiveness analysis was constructed using a Markov model with 5 health states. The Markov model was developed using patient data collected from the Xijing Hospital from January 1, 2016 to January 1, 2021. The time horizon was set at 30 years, and a 6-month cycle length was used in the model. Costs and ICERs were reported in 2020 U.S. dollars. One-way sensitivity analysis and probabilistic sensitivity analysis (PSA) were used to test the uncertainties. A Chinese health-care system perspective was used.Results: In the base case, the data of 231 VTE patients were calculated in the base case analysis retrospectively. The RIV group resulted in a mean VTE attributable to 95% effective treatment. API, DAB, and VKA have a negative ICER (−187017.543, −284,674.922, and −9,283.339, respectively) and were absolutely dominated. The Markov model results confirmed this observation. The ICER of the API and RIV was negative (−216176.977), which belongs to the absolute inferiority scheme, and the ICER value of the DAB and VKA versus RIV was positive (110,577.872 and 836,846.343). Since the ICER of DAB and VKA exceeds the threshold, RIV therapy was likely to be the best choice for the treatment of VTE within the acceptable threshold range. The results of the sensitivity analysis revealed that the model output varied mostly with the cost in the DAB on-treatment therapy. In a probabilistic sensitivity analysis of 1,000 patients for 30 years, RIV has 100% probability of being cost-effective compared with other regimens when the WTP is $10973 per QALY. When WTP exceeded $148,000, DAB was more cost-effective than RIV.Conclusions: Compared with LMWH + VKA and API, the results proved that RIV may be the most cost-effective treatment for VTE patients in China. Our findings could be helpful for physicians in clinical decision-making to select the appropriate treatment option for VTE.

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