Reliability analysis of a multi-state system with identical units having two dependent components

2020 ◽  
pp. 1748006X2095747
Author(s):  
Funda Iscioglu ◽  
Aysegul Erem
Keyword(s):  
Performance Evaluation ◽  
Reliability Analysis ◽  
Order Statistics ◽  
Performance Measures ◽  
Dynamic Performance ◽  
State System ◽  
Binary State ◽  
Degradation Rates ◽  
The Mean ◽  
Bivariate Order Statistics

The performance evaluation of a system having n identical units, each of which consists of two components has been successfully discussed in binary-state reliability analysis. In this paper, we study the performance evaluation of a multi-state system based on bivariate order statistics. The multi-state system consists of n independent and identical units, each having two components. The components of each unit are assumed to be s-dependent. However, the units work s-independently with each other. The system and each component of each unit having three performance levels “0 (failure), 1 (partially working) and 2 (completely working)” are considered. The degradation of the components follows Markov Process and also Farlie-Gumbel-Morgenstern distribution is used to model the s-dependence of the components. The reliability analysis of a multi-state k-out-of- n system are evaluated under the assumptions. Some dynamic performance measures for the system such as the mean residual and mean past lifetime functions based on bivariate order statistics are also evaluated. The performance of the system is especially examined for different values of s-dependence parameter, the degradation rates and different number of units for the system. The results are supported with some numerical examples and graphical representations.

A generalized model selection framework for multi-state failure data analysis

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rajkumar Bhimgonda Patil ◽  
Suyog Subhash Patil ◽  
Gajanand Gupta ◽  
Anand K. Bewoor
Keyword(s):  
Data Analysis ◽  
Reliability Analysis ◽  
State System ◽  
Numerical Control ◽  
Failure Behavior ◽  
Class Iii ◽  
Content Type ◽  
Failure Data ◽  
Binary State ◽  
Design Attribute

PurposeThe purpose of this paper is to carry out a reliability analysis of a mechanical system considering the degraded states to get a proper understanding of system behavior and its propagation towards complete failure.Design/methodology/approachThe reliability analysis of computerized numerical control machine tools (CNCMTs) using a multi-state system (MSS) approach that considers various degraded states rather than a binary approach is carried out. The failures of the CNCMT are classified into five states: one fully operational state, three degraded states and one failed state.FindingsThe analysis of failure data collected from the field and tests conducted in the laboratory provided detailed understandings about the quality of the material and its failure behavior used in designing and the capability of the manufacturing system. The present work identified that Class II (major failure) is critical from a maintainability perspective whereas Class III (moderate failure) and Class IV (minor failure) are critical from a reliability perspective.Research limitations/implicationsThis research applies to reliability data analysis of systems that consider various degraded states.Practical implicationsMSS reliability analysis approach will help to identify various degraded states of the system that affect the performance and productivity and also to improve system reliability, availability and performance.Social implicationsIndustrial system designers recognized that reliability and maintainability is a critical design attribute. Reliability studies using the binary state approach are insufficient and incorrect for the systems with degraded failures states, and such analysis can give incorrect results, and increase the cost. The proposed MSS approach is more suitable for complex systems such as CNCMT rather than the binary-state system approach.Originality/valueThis paper presents a generalized framework MSS's failure and repair data analysis has been developed and applied to a CNCMT.

scholarly journals The 8-item Morisky medication adherence scale: validation of a Portuguese version in HIV patients

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
A Aguiar ◽  
C Piñeiro ◽  
R Serrão ◽  
R Duarte
Keyword(s):  
Medication Adherence ◽  
Psychometric Properties ◽  
Reliability Analysis ◽  
Cronbach’S Alpha ◽  
Portuguese Version ◽  
Cronbach's Alpha ◽  
Adherence To Medication ◽  
Morisky Medication Adherence Scale ◽  
Adherence Scale ◽  
The Mean

Abstract Background Antiretroviral therapy (ART) has the most effective treatment for people with HIV, but its effectiveness depends on the individual medication adherence. Morisky Medication Adherence Scale (MMAS-8) is one of the most widely used scales to assess patient adherence. Thus, we aimed to validate a Portuguese version of MMAS-8 and determine its psychometric properties in HIV positive patients. Methods A cross-sectional survey was conducted in Centro Hospitalar Universitário São João (Porto, northern Portugal) at the infectious diseases department. After authorization to use the scale - granted by the author - and, a standard forward-backwards procedure to translate MMAS-8 to Portuguese, the questionnaire was applied to 233 patients with HIV doing ART. Reliability was assessed using Cronbach's alpha and test-retest reliability. Three levels of adherence were considered: 0 to < 6 (low), 6 to < 8 (medium), 8 (high). Results In the studied sample, the mean age was 45.03 years (SD = 11.63), 80.3% men, 19.3% women and 1 transgender, and 53.8% had ≤9 years of education. The mean number of prescribed ART per patient was 1.76. The mean score for the medication adherence scale was 7.29 (SD = 6.74). For the reliability analysis, 12 patients were excluded due to missing data (n = 221). Regarding the level of adherence, 22.5% were low adhering, 71.6% medium and 5.9% high. Corrected item-total correlations showed that 1 item does not correlate very well with the overall scale and was dropped. Scale reliability analysis for the remaining 7 items revealed an overall Cronbach's alpha of 0.661. Women had a protective effect on adherence (OR = 0.31;95%CI:0.15-0.66). Number of years doing ART, age of participants, and type of residence didn't show to be correlated with adherence. Conclusions MMAS-8 is a reliable and valid measure to detect patients at risk of non-adherence. A satisfactory Cronbach's alfa (0.661) was obtained. In general, adherence to medication was medium or high. Key messages This scale can be applied nationwide in other different hospitals, as it could serve as a tool for measuring adherence to ART that can allow for better health care to the ones that are low adhering. A Portuguese version of the MMAS-8 was created for measuring adherence to ART that maintained a similar structure to the original MMAS-8 and good psychometric properties.

Chemical characteristics and in situ ruminal parameters of barley for cattle: Comparison of the malting cultivar AC Metcalfe and five feed cultivars

2008 ◽  
Vol 88 (4) ◽  
pp. 711-719 ◽  
Author(s):  
Kenton J Hart ◽  
Brian G Rossnagel ◽  
Peiqiang Yu
Keyword(s):  
Nutritive Value ◽  
Degradation Kinetics ◽  
Starch Degradation ◽  
Barley Cultivars ◽  
Degradation Rates ◽  
Key Words Barley ◽  
In Situ Degradation ◽  
The Mean ◽  
Pass Through

The objective of this study was to compare the most widely grown barley cultivar in Canada, AC Metcalfe, a malting type barley, with five feed cultivars. Barley cultivars were grown at one location during 3 consecutive years and barley samples were milled to pass through a 1-mm screen and analysed to determine nutritive value. Additional samples were passed through a roller mill with a gap set at 1.12 mm and incubated ruminally for 0, 2, 4, 8, 12, 24, and 48 h in 3 dry Holstein cows fitted with rumen cannulae. The rate and extent of rumen digestion were estimated. AC Metcalfe had a higher (P < 0.001) concentration of NDF, and lower (P < 0.05) concentrations of non structural carbohydrates, starch, ADF, total digestible nutrients, and fermentable cell wall carbohydrates compared with the mean of the feed cultivars. The malting cultivar had a higher (P < 0.001) soluble DM fraction, lower (P < 0.05) CP and starch degradation rates, and a lower (P < 0.001) ruminally degradable starch concentration compared with the mean of the five feed cultivars. The results demonstrate that there are only small differences in terms of chemical composition and in situ degradation kinetics between the malting cultivar AC Metcalfe and the five feed cultivars of barley reported here. Key words: Barley, energy, protein, ruminants

Bayesian Networks Application in Multi-State System Reliability Analysis

2013 ◽  
Vol 347-350 ◽  
pp. 2590-2595 ◽  
Author(s):  
Sheng Zhai ◽  
Shu Zhong Lin
Keyword(s):  
Bayesian Network ◽  
Reliability Analysis ◽  
System Reliability ◽  
Prior Probability ◽  
State System ◽  
Weak Links ◽  
Uncertain Reasoning ◽  
Reliability Modeling ◽  
Line System ◽  
Reliability Indices

Aiming at the limitations of traditional reliability analysis theory in multi-state system, a method for reliability modeling and assessment of a multi-state system based on Bayesian Network (BN) is proposed with the advantages of uncertain reasoning and describing multi-state of event. Through the case of cell production line system, in this paper we will discuss how to establish and construct a multi-state system model based on Bayesian network, and how to apply the prior probability and posterior probability to do the bidirectional inference analysis, and directly calculate the reliability indices of the system by means of prior probability and Conditional Probability Table (CPT) . Thereby we can do the qualitative and quantitative analysis of the multi-state system reliability, identify the weak links of the system, and achieve assessment of system reliability.

Dynamic performance evaluation of multi – state systems under non – homogeneous continuous time Markov process degradation using lifetimes in terms of order statistics

2017 ◽  
Vol 231 (3) ◽  
pp. 255-264 ◽  
Author(s):  
Funda Iscioglu
Keyword(s):  
Markov Process ◽  
Order Statistics ◽  
Continuous Time ◽  
Dynamic Performance ◽  
Real Life ◽  
State Change ◽  
Transition Rates ◽  
Lifetime Analysis ◽  
Complete Failure ◽  
Effect Of Age

In multi-state modelling a system and its components have a range of performance levels from perfect functioning to complete failure. Such a modelling is more flexible to understand the behaviour of mechanical systems. To evaluate a system’s dynamic performance, lifetime analysis of a multi-state system has been considered in many research articles. The order statistics related analysis for the lifetime properties of multi-state k-out-of-n systems have recently been studied in the literature in case of homogeneous continuous time Markov process assumption. In this paper, we develop the reliability measures for multi-state k-out-of-n systems by assuming a non-homogeneous continuous time Markov process for the components which provides time dependent transition rates between states of the components. Therefore, we capture the effect of age on the state change of the components in the analysis which is typical of many systems and more practical to use in real life applications.

Modeling multi-state system reliability analysis in a power station under fatal and nonfatal shocks: a simulation approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Reza Pourhassan ◽  
Sadigh Raissi ◽  
Arash Apornak
Keyword(s):  
Reliability Analysis ◽  
System Reliability ◽  
System Performance ◽  
Failure Process ◽  
State System ◽  
Failure Behavior ◽  
Simulation Approach ◽  
Critical System ◽  
Content Type ◽  
System Reliability Analysis

PurposeIn some environments, the failure rate of a system depends not only on time but also on the system condition, such as vibrational level, efficiency and the number of random shocks, each of which causes failure. In this situation, systems can keep working, though they fail gradually. So, the purpose of this paper is modeling multi-state system reliability analysis in capacitor bank under fatal and nonfatal shocks by a simulation approach.Design/methodology/approachIn some situations, there may be several levels of failure where the system performance diminishes gradually. However, if the level of failure is beyond a certain threshold, the system may stop working. Transition from one faulty stage to the next can lead the system to more rapid degradation. Thus, in failure analysis, the authors need to consider the transition rate from these stages in order to model the failure process.FindingsThis study aims to perform multi-state system reliability analysis in energy storage facilities of SAIPA Corporation. This is performed to extract a predictive model for failure behavior as well as to analyze the effect of shocks on deterioration. The results indicate that the reliability of the system improved by 6%.Originality/valueThe results of this study can provide more confidence for critical system designers who are engaged on the proper system performance beyond economic design.

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