A novel opportunistic maintenance strategy for systems with dependent main and auxiliary components

2020 ◽  
Vol 32 (1) ◽  
pp. 69-90 ◽  
Author(s):  
Jingyuan Shen ◽  
Yanjing Zhang ◽  
Yizhong Ma ◽  
Cong Lin
Keyword(s):  
System Reliability ◽  
Maintenance Strategy ◽  
Replacement Cost ◽  
The Matrix ◽  
Optimal Maintenance ◽  
Sensitivity Studies ◽  
Inspection And Maintenance ◽  
Environmental Shocks ◽  
Main Component ◽  
Cost Parameters

Abstract The complexity of dependence between different types of components results in many challenges to estimate system reliability and to optimize maintenance plans. In this paper, we develop a reliability model to study the failure dependence of a system with a main component and several protective auxiliary components. Damage to the main component caused by random environmental shocks depends on the number of auxiliary components in operation. When the execution of inspection and maintenance actions during system operation is difficult, failures of the main component provide opportunities to inspect and replace the auxiliary components. We derive the system reliability using Laplace transforms and the matrix method. The optimization problem is solved by an enumeration method. A numerical example and sensitivity studies of cost parameters show how the evolution of the parameters influences the optimal maintenance strategy. The results show that a high replacement threshold of the auxiliary components is required when the replacement cost of the main component is high. Conversely, the threshold could be adjusted to a lower level when the replacement cost of the auxiliary components and the downtime cost increase.

scholarly journals THE MATRIX PROCEDURES FOR CALCULATION OF IMPORTANCE MEASURES

2019 ◽  
pp. 71-78
Author(s):  
Elena Zaitseva ◽  
Peter Sedlacek ◽  
Andrej Forgac
Keyword(s):  
Structure Function ◽  
System Reliability ◽  
Boolean Logic ◽  
Mathematical Representation ◽  
Complex Concept ◽  
System Components ◽  
The Matrix ◽  
Importance Analysis ◽  
The Impact ◽  
Fixed System

System reliability/availability is a complex concept that is evaluated based on numerous indices and measures. There are different methods for the calculation of these indices and measures in reliability analysis. Some of the most used indices are important measures. These measures allow us to evaluate the influence of fixed system components or set of components to the system reliability/availability. Importance measures are used today to allow for various aspects of the impact of system elements on its failure or operability. Analysis of element importance is used in the system design, diagnosis, and optimization. In this paper new algorithms for the calculation, some of the important measures are developed based on the matrix procedures. This paper's goal is the development of a new algorithm to calculate importance measures of the system based on the matrix procedures that can be transformed in the parallel procedures/algorithms. These algorithms are developed based on the application of Logical Differential Calculus of Boolean logic for the important analysis of the system. The application of parallel algorithms in importance analysis allows the evaluation of the system of large dimensions. Importance specific of the proposed matrix procedures for calculation of importance measures is the application of structure-function for the mathematical representation of the investigated system. This function defined the correlation of the system components states and system reliability/ availability. The structure-function, in this case, is defined as a truth vector to be used in the matrix transformation. The truth vector of a Boolean function is a column of the truth table of function if the values of the variables are lexicographically ordered. Therefore, the structure-function of any system can be represented by the truth vector of 2n elements un-ambiguously.

scholarly journals Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET-Europe

2013 ◽  
Vol 6 (2) ◽  
pp. 3013-3057
Author(s):  
B. Torres ◽  
C. Toledano ◽  
A. Berjón ◽  
D. Fuertes ◽  
V. Molina ◽  
...  
Keyword(s):  
Calibration Method ◽  
Field Of View ◽  
Pointing Error ◽  
Vicarious Calibration ◽  
Movement Correction ◽  
Measurement Protocol ◽  
The Matrix ◽  
First Results ◽  
Sensitivity Studies

Abstract. Sensitivity studies indicate that among the different error sources of ground-based sky radiometer observations, the pointing error has an important role in the correct retrieving of aerosol properties, being specially critical for the characterization of desert dust aerosol. The present work analyzes the first results of two new measurements, cross and matrix, specifically designed for an evaluation of the pointing error in the standard instrument of the Aerosol Robotic Network, the Cimel CE-318 sun-photometer. The first part of the analysis contains a preliminary study whose results conclude on the need of a sun movement correction for the correct evaluation of the pointing error from both new measurements. Once this correction is applied, both measurements show an equivalent behavior with differences under 0.01° in the evaluation of the pointing error. The second part of the analysis includes the incorporation of the cross scenario in the AERONET routine measurement protocol in order to monitor the pointing error in field instruments. Using the data collected for more than a year, the pointing error is evaluated on 7 sun-photometers belonging to AERONET-Europe. The pointing error values registered are generally smaller than 0.01° though in some instruments values up to 0.03° have been observed. Moreover, the pointing error evaluation has shown that this measure can be used to detect mechanical problems in the robots or dirtiness in the quadrant detector due to the stable behavior of the values against time and solar zenith angle. At the same time, the matrix scenario can be used to derive the value of the field of view. The methodology implemented and the characterization of five sun-photometers is presented in the last part of the study. To validate the method, a comparison with field of view values obtained from the vicarious calibration method was developed. The differences between both techniques are under 3%.

Optimization of equal-cycle maintenance strategy considering imperfect preventive maintenance

2021 ◽  
pp. 095440892110638
Author(s):  
Xinlong Li ◽  
Yan Ran ◽  
Genbao Zhang
Keyword(s):  
Decision Making ◽  
Preventive Maintenance ◽  
Maintenance Cost ◽  
Maintenance Strategy ◽  
Action Unit ◽  
Cost Rate ◽  
Equipment Reliability ◽  
Optimal Maintenance ◽  
Important Means ◽  
Maintenance Decision

Preventive maintenance is an important means to extend equipment life and improve equipment reliability. Traditional preventive maintenance decision-making is often based on components or the entire system, the granularity is too large and the decision-making is not accurate enough. The meta-action unit is more refined than the component or system, so the maintenance decision-making based on the meta-action unit is more accurate. Therefore, this paper takes the meta-action unit as the research carrier, considers the imperfect preventive maintenance, based on the hybrid hazard rate model, established the imperfect preventive maintenance optimization model of the meta-action unit, and the optimization solution algorithm was given for the maintenance strategy. Finally, through numerical analysis, the validity of the model is verified, and the influence of different maintenance costs on the optimal maintenance strategy and optimal maintenance cost rate is analyzed.

scholarly journals Measurements on pointing error and field of view of Cimel-318 Sun photometers in the scope of AERONET

2013 ◽  
Vol 6 (8) ◽  
pp. 2207-2220 ◽  
Author(s):  
B. Torres ◽  
C. Toledano ◽  
A. Berjón ◽  
D. Fuertes ◽  
V. Molina ◽  
...  
Keyword(s):  
Calibration Method ◽  
Pointing Error ◽  
Vicarious Calibration ◽  
Movement Correction ◽  
Measurement Protocol ◽  
The Matrix ◽  
Mechanical Faults ◽  
Sensitivity Studies ◽  
Error Estimations

Abstract. Sensitivity studies indicate that among the diverse error sources of ground-based sky radiometer observations, the pointing error plays an important role in the correct retrieval of aerosol properties. The accurate pointing is specially critical for the characterization of desert dust aerosol. The present work relies on the analysis of two new measurement procedures (cross and matrix) specifically designed for the evaluation of the pointing error in the standard instrument of the Aerosol Robotic Network (AERONET), the Cimel CE-318 Sun photometer. The first part of the analysis contains a preliminary study whose results conclude on the need of a Sun movement correction for an accurate evaluation of the pointing error from both new measurements. Once this correction is applied, both measurements show equivalent results with differences under 0.01° in the pointing error estimations. The second part of the analysis includes the incorporation of the cross procedure in the AERONET routine measurement protocol in order to monitor the pointing error in field instruments. The pointing error was evaluated using the data collected for more than a year, in 7 Sun photometers belonging to AERONET sites. The registered pointing error values were generally smaller than 0.1°, though in some instruments values up to 0.3° have been observed. Moreover, the pointing error analysis shows that this measurement can be useful to detect mechanical problems in the robots or dirtiness in the 4-quadrant detector used to track the Sun. Specifically, these mechanical faults can be detected due to the stable behavior of the values over time and vs. the solar zenith angle. Finally, the matrix procedure can be used to derive the value of the solid view angle of the instruments. The methodology has been implemented and applied for the characterization of 5 Sun photometers. To validate the method, a comparison with solid angles obtained from the vicarious calibration method was developed. The differences between both techniques are below 3%.

scholarly journals Research on Multi-Attribute Decision-Making in Condition-Based Maintenance for Power Transformers Based on Cloud and Kernel Vector Space Models

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5948
Author(s):  
Renxi Gong ◽  
Siqiang Li ◽  
Weiyu Peng
Keyword(s):  
Decision Making ◽  
Vector Space ◽  
Assessment System ◽  
Condition Based Maintenance ◽  
Power Transformers ◽  
Maintenance Strategy ◽  
Cloud Models ◽  
Optimal Maintenance ◽  
Maintenance Decision ◽  
Vector Space Models

Decision-making for the condition-based maintenance (CBM) of power transformers is critical to their sustainable operation. Existing research exhibits significant shortcomings; neither group decision-making nor maintenance intention is considered, which does not satisfy the needs of smart grids. Thus, a multivariate assessment system, which includes the consideration of technology, cost-effectiveness, and security, should be created, taking into account current research findings. In order to address the uncertainty of maintenance strategy selection, this paper proposes a maintenance decision-making model composed of cloud and vector space models. The optimal maintenance strategy is selected in a multivariate assessment system. Cloud models allow for the expression of natural language evaluation information and are used to transform qualitative concepts into quantitative expressions. The subjective and objective weights of the evaluation index are derived from the analytic hierarchy process and the grey relational analysis method, respectively. The kernel vector space model is then used to select the best maintenance strategy through the close degree calculation. Finally, an optimal maintenance strategy is determined. A comparison and analysis of three different representative maintenance strategies resulted in the following findings: The proposed model is effective; it provides a new decision-making method for power transformer maintenance decision-making; it is simple, practical, and easy to combine with the traditional state assessment method, and thus should play a role in transformer fault diagnosis.

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