scholarly journals ЕКСПРЕС-АНАЛІЗ ВПЛИВУ ІННОВАЦІЙНИХ РІШЕНЬ МЕХАНІЗМІВ НА НАДІЙНІСТЬ ШКАРПЕТКОВИХ АВТОМАТІВ

2021 ◽  
Vol 146 (3) ◽  
pp. 48-57
Author(s):  
Л. М. Березін
Keyword(s):  
Reliability Analysis ◽  
Failure Time ◽  
Matrix Theory ◽  
Numerical Estimate ◽  
Automatic Machine ◽  
Data Matrix ◽  
A Posteriori ◽  
Limited Information ◽  
Innovative Solutions ◽  
Operational Assessment

Purpose: development of a methodology for operational assessment of the influence of innovative solutions to the technical and operational characteristics of individual mechanisms and systems on the reliability of the sock automatic machine on a posteriori information about failures in production.Methodology:  the method of search, description, analogies and analysis of information is used to audit the set of possible solutions to the subject of research, the basics of reliability theory, methods for assessing reliability indicators based on experimental data, matrix theory, elements of numerical methods and methodology of a posteriori reliability analysis of structurally complex technical systems. Findings: the calculation algorithm and mathematical support for operational assessment of influence of technical and operational changes of one of mechanisms on reliability of the sock automatic machine as a whole in the conditions of uncertainty of the information about failures and sources of its receipt are presented. The advantages of the proposed approach in comparison with the traditional one are shown, which allows to reduce the design duration while ensuring the required quality and minimizing costs by limiting tests and calculations. A numerical estimate of the degree of influence on the reliability of the sock automatic machine of changes in the design of the knitting mechanism is obtained. It is shown that the increase in the average failure time to 24.82 hours, when changing the technical characteristics of the knitting mechanism leads to an increase in this indicator for the machine as a whole to 1.24 hours. Originality: it is the further development of the theory and methodology of reliability analysis of sock automatic machines at the stages of design or modernization in cases of controlled variety of options for innovative mechanisms with limited information about failures and while maintaining functional and structural relationships. Practical value: the method of modeling the reliability of the sock automatic machine according to the innovative solutions of its mechanisms is proposed, which minimizes the costs of additional tests and calculations. The results of the above concept of the analysis of the reliability of the machine confirmed the sufficient accuracy of the calculations at the stage before the design preparation, which allows it to be used for other knitting machines.

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.

Copula-based reliability analysis of gamma degradation process and Weibull failure time

2019 ◽  
Vol 36 (5) ◽  
pp. 654-668 ◽  
Author(s):  
Somayeh Mireh ◽  
Ahmad Khodadadi ◽  
Firoozeh Haghighi
Keyword(s):  
Reliability Analysis ◽  
Failure Time ◽  
Degradation Process ◽  
Copula Function ◽  
Closed Form Expression ◽  
Suggested Approach ◽  
Content Type ◽  
Dependency Structure ◽  
Testing Experiment ◽  
Hard Failure

Purpose The purpose of this paper is the reliability analysis for systems with dependent gamma degradation process and Weibull failure time. Design/methodology/approach Consider a life testing experiment in which a sample of n devices starts to operate at t=0 and the data are available on failure time and failure-evolving process on each individual, called in some contents wear or degradation. Ignoring the between performance characteristics dependency structure may lead us to different reliability estimations, while the dependency justly exists. In previous research, dependency between the degradation process and hard failure time has been studied in limited detail (special closed form expression). Thereafter, the dependency between two degradation processes with the same structure (gamma process) in a system is considered using the copula function. Findings The results indicate that ignoring the dependency structure may lead us to different reliability estimations while the dependency justly exists. Originality/value This study gives some contributions that evaluate reliability metrics with more than one failure mechanism that may not be independent and possibly follow a different distribution function. The authors have used the copula function as a basis to develop a proposal model and analysis methods. In addition, the authors discussed the identifiability of the copula. Finally, simulation data were used to review the suggested approach.

An Efficient Reliability Analysis Method for Structures With Epistemic Uncertainty Using Evidence Theory

2014 ◽  
Author(s):  
Zhe Zhang ◽  
Chao Jiang ◽  
G. Gary Wang ◽  
Xu Han
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Epistemic Uncertainty ◽  
Limit State ◽  
Computational Cost ◽  
Evidence Theory ◽  
State Function ◽  
Limited Information ◽  
Design Point ◽  
Engineering Problems

Evidence theory has a strong ability to deal with the epistemic uncertainty, based on which the uncertain parameters existing in many complex engineering problems with limited information can be conveniently treated. However, the heavy computational cost caused by its discrete property severely influences the practicability of evidence theory, which has become a main difficulty in structural reliability analysis using evidence theory. This paper aims to develop an efficient method to evaluate the reliability for structures with evidence variables, and hence improves the applicability of evidence theory for engineering problems. A non-probabilistic reliability index approach is introduced to obtain a design point on the limit-state surface. An assistant area is then constructed through the obtained design point, based on which a small number of focal elements can be picked out for extreme analysis instead of using all the elements. The vertex method is used for extreme analysis to obtain the minimum and maximum values of the limit-state function over a focal element. A reliability interval composed of the belief measure and the plausibility measure is finally obtained for the structure. Two numerical examples are investigated to demonstrate the effectiveness of the proposed method.

scholarly journals FPGA-Based Degradation and Reliability Monitor for Underground Cables

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 1995
Author(s):  
Unai Garro ◽  
Eñaut Muxika ◽  
Jose Ignacio Aizpurua ◽  
Mikel Mendicute
Keyword(s):  
Probability Distribution ◽  
Thermal Degradation ◽  
Reliability Analysis ◽  
Failure Time ◽  
Thermal Heating ◽  
Expectation Values ◽  
Underground Cables ◽  
Fpga Architecture ◽  
Degradation Models ◽  
Mc Simulation

The online RUL estimation of underground cables and their reliability analysis requires obtaining the cable failure time probability distribution. MC simulations of complex thermal heating and electro-thermal degradation models can be employed for this analysis, but uncertainties need to be considered in the simulations, to produce accurate RUL expectation values and confidence margins for the results. The process requires performing large simulation sets, based on past temperature or load measurements and future load predictions. FPGA permit accelerating simulations for live analysis, but the thermal models involved are complex to be directly implemented in hardware logic. A new standalone FPGA architecture has been proposed for the fast and on-site degradation and reliability analysis of underground cables, based on MC simulation, and the effect of load uncertainties on the predicted cable EOL has been analyzed from the results.

A Hybrid Reliability Approach Based on Probability and Interval for Uncertain Structures

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
C. Jiang ◽  
X. Han ◽  
W. X. Li ◽  
J. Liu ◽  
Z. Zhang
Keyword(s):  
Reliability Analysis ◽  
Limit State ◽  
Random Variables ◽  
Normal Space ◽  
Uncertain Parameters ◽  
Limited Information ◽  
Reliability Models ◽  
Distribution Parameters ◽  
Hybrid Reliability ◽  
Monotonicity Analysis

Traditional reliability analysis generally uses probability approach to quantify the uncertainty, while it needs a great amount of information to construct precise distributions of the uncertain parameters. In this paper, a new reliability analysis technique is developed based on a hybrid uncertain model, which can deal with problems with limited information. All uncertain parameters are treated as random variables, while some of their distribution parameters are not given precise values but variation intervals. Due to the existence of the interval parameters, a limit-state strip enclosed by two bounding hyper-surfaces will be resulted in the transformed normal space, instead of a single hyper-surface as we usually obtain in conventional reliability analysis. All the limit-state strips are then summarized into two different classes and corresponding reliability analysis models are proposed for them. A monotonicity analysis is carried out for probability transformations of the random variables, through which effects of the interval distribution parameters on the limit state can be well revealed. Based on the monotonicity analysis, two algorithms are then formulated to solve the proposed hybrid reliability models. Three numerical examples are investigated to demonstrate the effectiveness of the present method.

scholarly journals The phylogeny and taxonomic status of the Chlorocystini (sensu stricto) (Homoptera, Tibicinidae)

1995 ◽  
Vol 65 (4) ◽  
pp. 201-231 ◽  
Author(s):  
A.J. de Boer
Keyword(s):  
Computer Program ◽  
Computer Analysis ◽  
Phylogenetic Reconstruction ◽  
Taxonomic Status ◽  
Sister Group ◽  
Sensu Stricto ◽  
Complete Data ◽  
Data Matrix ◽  
A Posteriori

The “Baeturia and related genera complex”, as defined earlier (De Boer, 1990) by shared aedeagal characters, is identified as the tribe Chlorocystini (sensu stricto). The Prasiini (sensu stricto) are identified as the sister group of the Chlorocystini (sensu stricto), while the genus Muda is recognized as the nearest outgroup. The phylogeny and biogeography of the sister group and outgroup is briefly discussed. Baeturia kuroiwae Matsumura is transferred to the genus Muda. A phylogenetic reconstruction of all 147 species of the Chlorocystini (sensu stricto) is presented, based on 154 characters and 409 character states. The computer program PAUP 3.1.1 (Swofford, 1993) was used for analysing the data; the genera Prasia and Muda were used as outgroups in this analysis. The results obtained from the computer analysis were slightly modified a posteriori, favouring some presumably phylogenetically important characters over strongly fluctuating ones. These final modifications were carried out with the aid of the computer program MacClade 3.0 (Maddison & Maddison, 1992). A complete data matrix and a list of characters and character states are given in an appendix; for descriptions and illustrations of these characters one is referred to previous publications.

scholarly journals A Practical Method of Nonprobabilistic Reliability and Parameter Sensitivity Analysis Based on Space-Filling Design

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Xin-dang He ◽  
Wen-xuan Gou ◽  
Yong-shou Liu ◽  
Zong-zhan Gao
Keyword(s):  
Sensitivity Analysis ◽  
Reliability Analysis ◽  
Computational Cost ◽  
Rank Correlation ◽  
Practical Method ◽  
Limited Information ◽  
Convex Model ◽  
Space Filling ◽  
Uncertainty Space ◽  
Space Filling Design

Using the convex model approach, the bounds of uncertain variables are only required rather than the precise probability distributions, based on which it can be made possible to conduct the reliability analysis for many complex engineering problems with limited information. In this paper, three types of convex model including interval, ellipsoid, and multiellipsoid convex uncertainty model are investigated, and a uniform model of nonprobabilistic reliability analysis is built. In the reliability analysis process, an effective space-filling design is introduced to generate representative samples of uncertainty space so as to reduce the computational cost and provide an accurate depiction of possible model outcome. Finally, Spearman’s rank correlation coefficient is used to perform parameters global sensitivity analysis. Three numerical examples are investigated to demonstrate the feasibility and accuracy of the presented method.

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