scholarly journals Estimation of the average time to failure of the turning steps according to the operation data

2019 ◽  
Vol 78 (1) ◽  
pp. 54-58
Author(s):  
M. V. Belousova ◽  
V. V. Bulatov
Keyword(s):  
Weibull Distribution ◽  
Failure Time ◽  
Operational Reliability ◽  
Likelihood Method ◽  
Point Estimate ◽  
Statistical Criterion ◽  
Time To Failure ◽  
Distribution Law ◽  
Software Environment ◽  
Technical Product

The purpose of this study is to determine the empirical law of the distribution of developments to the failure of the turning steps installed on passenger cars of locomotive traction. The correct choice of the distribution law for each technical product allows for the current calculation of reliability indicators, predicting them, as well as developing preventive measures for a specific technical product and leveling costs both during production and during operation.The article presents well-founded arguments that the failure time for turning steps is characterized by the Weibull distribution law. For confirmation, a statistical criterion for checking the deviation of the distribution from the normal one was applied.On the basis of carried statistic analysis a histogram of frequencies and a line of the density function of samples of failure time in the data fixation period from 2010 to 2017 were built. Results of applying the 2 agreement criterion in the same software environment revealed that the failure time of the closed turning step comply with the law of Weibull distribution. Authors suggest using the maximum likelihood method to identify Weibull distribution parameters, on the basis of which the value of the point estimate of the mean time to failure is calculated.Based on the research, it is concluded that this type of distribution law and the process of finding its parameters should be introduced into the program and methodology for assessing the operational reliability of the turning steps, when calculating the average time to failure of the steps, and consider the possibility of applying this law for analogous products.In conclusion, calculation of the pointed estimation of the average time to failure of the closed turning step was made on the basis of operational tests for one year in accordance with the adopted distribution law.

scholarly journals Best estimation for the Reliability of 2-parameter Weibull Distribution

2009 ◽  
Vol 6 (4) ◽  
pp. 705-710
Author(s):  
Baghdad Science Journal
Keyword(s):  
Maximum Likelihood ◽  
Weibull Distribution ◽  
Mean Square Error ◽  
Maximum Likelihood Method ◽  
Likelihood Method ◽  
Statistical Criterion ◽  
Mean Square ◽  
Simulation Process ◽  
The Mean ◽  
Two Parameter

This Research Tries To Investigate The Problem Of Estimating The Reliability Of Two Parameter Weibull Distribution,By Using Maximum Likelihood Method, And White Method. The Comparison Is done Through Simulation Process Depending On Three Choices Of Models (?=0.8 , ß=0.9) , (?=1.2 , ß=1.5) and (?=2.5 , ß=2). And Sample Size n=10 , 70, 150 We Use the Statistical Criterion Based On the Mean Square Error (MSE) For Comparison Amongst The Methods.

scholarly journals Reliability Estimation of Three Parameters Weibull Distribution based on Particle Swarm Optimization

2021 ◽  
pp. 35-42
Author(s):  
Zakariya Y Algamal ◽  
Ghalia Basheer
Keyword(s):  
Particle Swarm Optimization ◽  
Weibull Distribution ◽  
Continuous Distribution ◽  
Estimation Method ◽  
Particle Swarm ◽  
Reliability Estimation ◽  
Likelihood Method ◽  
Time To Failure ◽  
Swarm Optimization ◽  
Hazard Functions

The three-parameter Weibull distribution is a continuous distribution widely used in the study of reliability and life data. The estimation of the distribution parameters is an important problem that has received a lot of attention by researchers because of theirs effects in several measurements. In this research, we propose a particle swarm optimization (PSO) to estimate the three-parameter Weibull distribution and then to estimate the reliability and hazard functions. The real data results indicate that our proposed estimation method is significantly consistent in estimation compared to the maximum likelihood method. In terms of log likelihood and mean time to failure (MTTF). 

Effects of covariates on alternating recurrent events in accelerated failure time models

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Moumita Chatterjee ◽  
Sugata Sen Roy
Keyword(s):  
Recurrent Events ◽  
Failure Time ◽  
Likelihood Method ◽  
Model Parameters ◽  
Accelerated Failure Time ◽  
Survival Times ◽  
Copula Functions ◽  
Event Time ◽  
Accelerated Failure Time Models ◽  
Accelerated Failure

AbstractIn this article, we model alternately occurring recurrent events and study the effects of covariates on each of the survival times. This is done through the accelerated failure time models, where we use lagged event times to capture the dependence over both the cycles and the two events. However, since the errors of the two regression models are likely to be correlated, we assume a bivariate error distribution. Since most event time distributions do not readily extend to bivariate forms, we take recourse to copula functions to build up the bivariate distributions from the marginals. The model parameters are then estimated using the maximum likelihood method and the properties of the estimators studied. A data on respiratory disease is used to illustrate the technique. A simulation study is also conducted to check for consistency.

Dependability Analysis of Homogeneous Distributed Software/Hardware Systems

2015 ◽  
Vol 22 (02) ◽  
pp. 1550007
Author(s):  
G. Vijayalakshmi
Keyword(s):  
Reliability Analysis ◽  
Distributed System ◽  
Failure Time ◽  
Load Sharing ◽  
Accelerated Failure Time Model ◽  
Time To Failure ◽  
Critical Systems ◽  
Time Model ◽  
Distributed Software ◽  
Dependability Analysis

With the increasing demand for high availability in safety-critical systems such as banking systems, military systems, nuclear systems, aircraft systems to mention a few, reliability analysis of distributed software/hardware systems continue to be the focus of most researchers. The reliability analysis of a homogeneous distributed software/hardware system (HDSHS) with k-out-of-n : G configuration and no load-sharing nodes is analyzed. However, in practice the system load is shared among the working nodes in a distributed system. In this paper, the dependability analysis of a HDSHS with load-sharing nodes is presented. This distributed system has a load-sharing k-out-of-(n + m) : G configuration. A Markov model for HDSHS is developed. The failure time distribution of the hardware is represented by the accelerated failure time model. The software faults are detected during software testing and removed upon failure. The Jelinski–Moranda software reliability model is used. The maintenance personal can repair the system up on both software and hardware failure. The dependability measures such as reliability, availability and mean time to failure are obtained. The effect of load-sharing hosts on system hazard function and system reliability is presented. Furthermore, an availability comparison of our results and the results in the literature is presented.

scholarly journals KAJIAN RELIABILITAS PADA SISTEM SERI-PARALEL DENGAN EMPAT KOMPONEN

2018 ◽  
Vol 7 (1) ◽  
pp. 73-83
Author(s):  
Farhah Izzatul Jannah ◽  
Sudarno Sudarno ◽  
Alan Prahutama
Keyword(s):  
Weibull Distribution ◽  
System Reliability ◽  
Failure Time ◽  
Likelihood Estimation ◽  
Parallel System ◽  
Operating Conditions ◽  
Failure Time Data ◽  
Time Data ◽  
Rank Regression ◽  
Load Resistor

Reliability analysis is the analysis of the possibility that the product or service will function properly for a certain period of time under operating conditions without failure. One configuration of components that can be formed is a series-parallel system on a filter capacitor circuit using 4 components consisting of 2 rectifier diodes, 1 capacitor, and 1 load resistor. The data used to obtain the value of system reliability is the time of failure based on the assumption of failure of the independent component. The function of the form on the system can be expressed by Ф(x)= x1x3 + x1x4 + x2x3 + x2x4 - x1x3x4 - x2x3x4 - x1x2x3 - x1x2x4 + x1x2x3x4. The parameter values of each distribution are calculated using the Median Rank Regression Estimation (MRRE) and Maximum Likelihood Estimation (MLE) methods. To test the data following a certain distribution or not, the calculation is manually done with the Anderson-Darling (AD) test so that it is known that the failure time data of rectifier diode 1 follows the weibull distribution with parameters  and , failure time data of rectifier diode 2 follows weibull distribution with parameters  and , failure time data of capacitors follow normal distribution with parameters  and , and the failure time data of the load resistor following the gamma distribution with parameters  and . From the calculation of system reliability, it shows that the higher the intensity of the system fails it will affect the value of reliability to be lower. A serial system from a parallel system functions if there is at least one component j in one subsystem that functions. Keywords: Reliability, Series-Parallel, MRRE, MLE, AD.

Influence of Overheating Degree on Material Reliability of A390.0 Alloy

2012 ◽  
Vol 191 ◽  
pp. 23-28 ◽  
Author(s):  
Jaroslaw Piątkowski
Keyword(s):  
Tensile Strength ◽  
Distribution Function ◽  
Weibull Distribution ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Time To Failure ◽  
The Impact ◽  
Failure Evaluation ◽  
Graphic Interpretation ◽  
Gravity Cast

The object of the studies was A390.0 alloy (AlSi17Cu5Mg), similar to A3XX.X series, gravity cast into sand and metal moulds. This alloy is mainly used for cast pistons operating in I.C. engines, for cylinder blocks and housings of compressors, and for pumps and brakes. The A390.0 alloy was poured at temperatures 880 and 980°C, holding the melt for 30 minutes and casting from the temperature of 780°C. The assessment of the impact of the degree of overheating was to analysis the tensile strength. Studies were carried out on a normal-running fatigue testing machine, which was the mechanically driven resonant pulsator. For the needs of quantitative reliability evaluation and the time-to-failure evaluation, the procedures used in survival analysis, adapted to the analysis of failure-free operation with two-parametric Weibull distributions, were applied. Having determined the boundary value σ0 for Weibull distribution, the value of „m” modulus was computed along with other coefficients of material reliability, proposed formerly by the authors. Basing on the obtained results, a model of Weibull distribution function was developed for the tensile strength with respective graphic interpretation.

scholarly journals Heat Transfer Behavior of Green Roof Systems Under Fire Condition: A Numerical Study

Buildings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 206
Author(s):  
Gerzhova ◽  
Blanchet ◽  
Dagenais ◽  
Côté ◽  
Ménard
Keyword(s):  
Heat Transfer ◽  
Failure Time ◽  
Numerical Study ◽  
Fire Hazard ◽  
Green Roof ◽  
Green Roofs ◽  
Heat Transfer Process ◽  
Heat Fluxes ◽  
Substrate Thickness ◽  
Time To Failure

Currently, green roof fire risks are not clearly defined. This is because the problem is still not well understood, which raises concerns. The possibility of plants catching fire, especially during drought periods, is one of the reasons for necessary protection measures. The potential fire hazard for roof decks covered with vegetation has not yet been fully explored. The present study analyzes the performance of green roofs in extreme heat conditions by simulating a heat transfer process through the assembly. The main objective of this study was to determine the conditions and time required for the roof deck to reach a critical temperature. The effects of growing medium layer thickness (between 3 and 10 cm), porosity (0.5 to 0.7), and heating intensity (50, 100, 150, and 200 kW/m²) were examined. It was found that a green roof can protect a wooden roof deck from igniting with only 3 cm of soil coverage when exposed to severe heat fluxes for at least 25 minutes. The dependency of failure time on substrate thickness decreases with increasing heating load. It was also found that substrate porosity has a low impact on time to failure, and only at high heating loads.

scholarly journals A Dynamic Failure Time Degradation-Based Model

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1532
Author(s):  
Abdulhakim A. Albabtain ◽  
Mansour Shrahili ◽  
Lolwa Alshagrawi ◽  
Mohamed Kayid
Keyword(s):  
Hazard Rate ◽  
Failure Time ◽  
Degradation Process ◽  
Residual Lifetime ◽  
Time To Failure ◽  
Lifetime Distributions ◽  
Mean Residual Lifetime ◽  
Aging Properties ◽  
Degradation Models ◽  
Characterization Property

A novel methodology for modelling time to failure of systems under a degradation process is proposed. Considering the method degradation may have influenced the failure of the system under the setup of the model several implied lifetime distributions are outlined. Hazard rate and mean residual lifetime of the model are obtained and a numerical situation is delineated to calculate their amounts. The problem of modelling the amount of degradation at the failure time is also considered. Two monotonic aging properties of the model is secured and a characterization property of the symmetric degradation models is established.

Parameter Estimation of Weibull Distribution Model Based on Ant Colony Algorithm

2014 ◽  
Vol 1070-1072 ◽  
pp. 2073-2078
Author(s):  
Xiu Ji ◽  
Hui Wang ◽  
Chuan Qi Zhao ◽  
Xu Ting Yan
Keyword(s):  
Parameter Estimation ◽  
Maximum Likelihood ◽  
Weibull Distribution ◽  
Ant Colony Algorithm ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Ant Colony ◽  
Likelihood Method ◽  
Distribution Model ◽  
Algorithm Theory

It is difficult to estimate the parameters of Weibull distribution model using maximum likelihood estimation based on particle swarm optimization (PSO) theory for which is easy to fall into premature and needs more variables, ant colony algorithm theory was introduced into maximum likelihood method, and a parameter estimation method based on ant colony algorithm theory was proposed, an example was simulated to verify the feasibility and effectiveness of this method by comparing with ant colony algorithm and PSO.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Analysis of HDPE Failure Data in Support of Development of Flaw Acceptance Criteria for Butt Fusion Joints

2020 ◽  
Author(s):  
Cheng Liu ◽  
Douglas Scarth ◽  
Douglas P. Munson ◽  
Ryan Wolfe
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Failure Time ◽  
Slow Crack Growth ◽  
Time To Failure ◽  
Acceptance Criteria ◽  
Failure Data ◽  
Criteria For Evaluation ◽  
Hdpe Pipes

Abstract There is a need for ASME B&PV Code procedures and acceptance criteria for evaluation of flaws detected by inspection of high density polyethylene (HDPE) piping items in safety Class 3 systems. To support the development of flaw acceptance criteria for butt fusion joints in HDPE pipes, a series of coupon tests have been completed for specimens cut from butt fused HDPE pipes with surface or subsurface flaws placed in the joints prior to fusion process. Specimens containing known flaw sizes were tested under axial load at accelerated stresses and temperatures until failure; or until a prescribed number of test hours was reached. The failure time from the tests has been correlated to the net section stress and the stress intensity factor, and the results showed that the failure time can be better represented by the stress intensity factor. The test results were then used to fit the Brown and Lu formula that predicts the time to failure due to the slow crack growth of flaws as a function of stress intensity factor and temperature. With the developed Brown and Lu equation, the allowable stress intensity factors for a piping lifetime of 50 years at the maximum code allowable temperature of 60°C have been proposed for both surface and subsurface flaws in HDPE butt fusion joints. Examples of what might be corresponding allowable flaw sizes in the butt fusion joints of piping are also provided.

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