scholarly journals Reliability and Availability Analysis of Arepairable System With Two Types of Failure

2015 ◽  
Vol 4 (1) ◽  
pp. 39
Author(s):  
M. A. El-Damcese ◽  
M. S. Shama
Keyword(s):  
System Reliability ◽  
Repairable System ◽  
Time To Failure ◽  
Repair Rate ◽  
System Parameters ◽  
Availability Analysis ◽  
Reliability Characteristics ◽  
The Mean ◽  
Mean Time ◽  
Reliability And Availability

This paper investigates reliability and availability of a repairable system with two types of failure. Let failure rate and repair rate of [type1, type2] components are assumed to be exponentially distributed. The expressions of availability and reliability characteristics such as the system reliability and the mean time to failure are derived. We used several cases to analyze graphically the effect of various system parameters on the reliability system and availability system.

A MARKOV REPAIRABLE SYSTEM INVOLVING AN IMPERFECT SERVICE STATION WITH MULTIPLE VACATIONS

2005 ◽  
Vol 22 (04) ◽  
pp. 555-582 ◽  
Author(s):  
JAU-CHUAN KE ◽  
CHUEN-HORNG LIN
Keyword(s):  
Repairable System ◽  
System Failure ◽  
Service Station ◽  
System Parameters ◽  
Failure Frequency ◽  
The Mean ◽  
Repair Facility ◽  
Markov Repairable System ◽  
Mean Time ◽  
Reliability And Availability

The main purpose of this paper is to study the reliability and availability of a system with M operating devices, m spares, and an imperfect service station that takes vacations. Specifically, once there are no failed devices in the system, the service station takes consecutive vacations until there is at least one failed device upon its return from vacation. The service station may break down and require repair at a repair facility. This paper derives the reliability, the mean time to system failure, the availability, and failure frequency of the K-out-of-M + m system. Numerical simulation of the impacts of system parameters as well as sensitivity analysis for the reliability, the mean time to system failure, the availability and failure frequency is performed.

scholarly journals Multi-Machine Repairable System with One Unreliable Server and Variable Repair Rate

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1299
Author(s):  
Shengli Lv
Keyword(s):  
Steady State ◽  
Transient State ◽  
Repairable System ◽  
Repair Rate ◽  
Numerical Illustration ◽  
Transform Method ◽  
Unreliable Server ◽  
Busy Time ◽  
The Mean ◽  
Mean Time

This paper analyzed the multi-machine repairable system with one unreliable server and one repairman. The machines may break at any time. One server oversees servicing the machine breakdown. The server may fail at any time with different failure rates in idle time and busy time. One repairman is responsible for repairing the server failure; the repair rate is variable to adapt to whether the machines are all functioning normally or not. All the time distributions are exponential. Using the quasi-birth-death(QBD) process theory, the steady-state availability of the machines, the steady-state availability of the server, and other steady-state indices of the system are given. The transient-state indices of the system, including the reliability of the machines and the reliability of the server, are obtained by solving the transient-state probabilistic differential equations. The Laplace–Stieltjes transform method is used to ascertain the mean time to the first breakdown of the system and the mean time to the first failure of the server. The case analysis and numerical illustration are presented to visualize the effects of the system parameters on various performance indices.

Research on Spurious Trip of 1oo2 Safety Instruments of Petrochemical Installation with Repair Considered

2010 ◽  
Vol 118-120 ◽  
pp. 596-600
Author(s):  
Jian Xin Zhu ◽  
Xue Dong Chen ◽  
Shi Yi Bao
Keyword(s):  
Failure Rate ◽  
System Reliability ◽  
Repairable System ◽  
Time To Failure ◽  
Redundant System ◽  
Common Cause ◽  
System A ◽  
Definition Of ◽  
Mean Time ◽  
Complex Influence

An innovative nuisance trip calculation method based on Markov model was proposed in this paper which was used to evaluate the effect of repairment on system reliability. By analysis of the availabilities of classic 1 out of 2 (1oo2) repairable system, a new definition of spurious trip was put forwarded where online repair was considered. Compared with the benefits obtained by online repairment, the repair-caused-nuisance-trip was analyzed in this paper. Numerical calculation revealed that the online repair is helpful for anti-spurious trip in 1oo2 redundant system. Dangerous failures, if not repaired or cannot be online fixed, have complex influence on system reliability. The dangerous failure is sometimes benefit for anti-spurious performance if it is not repaired. But Mean Time To Failure Spurious (MTTFs) reduces with the increase of dangerous failure provided that dangerous failure rate is bigger than safe failure rate. Meanwhile, the finding that common cause can reduce the chance of nuisance trip was also proposed in this paper, though the influence is too small to be neglected.

Reliability of mission-based k-out-of-n systems with exponential phase durations and component lifetimes

2020 ◽  
pp. 1748006X2096930
Author(s):  
Bora Çekyay
Keyword(s):  
System Reliability ◽  
Transition Probabilities ◽  
General System ◽  
System Structure ◽  
Time To Failure ◽  
Long Run ◽  
Reliability Characteristics ◽  
Mission Change ◽  
Component Failure Rates ◽  
Mean Time

This paper focuses on the reliability analysis of [Formula: see text]-out-of-[Formula: see text] systems which are designed to perform a given mission consisting of several distinct phases. As the phases of the mission change, the reliability characteristics of the system and the system structure vary accordingly. The phase transition probabilities, phase durations, and component failure rates are dependent on the number of operating components. Moreover, the system is allowed to have cold, warm, or hot standby components. We propose computationally tractable methods to compute the system reliability, mean time to failure, and long-run availability for such a general system structure. We also provide a numerical analysis to show the applicability and the empirical computational complexity of the proposed methods.

A Method for the Calculation of the Mean Time To Failure (MTTF) of Repairable System

2008 ◽  
Vol 44-46 ◽  
pp. 813-820 ◽  
Author(s):  
Jian Xin Zhu ◽  
Li J. Wang ◽  
Shi Yi Bao ◽  
W.P. Wang ◽  
Zeng Liang Gao
Keyword(s):  
Single Unit ◽  
Management Strategy ◽  
Great Influence ◽  
Repairable System ◽  
Time To Failure ◽  
Test Interval ◽  
Operating Cycle ◽  
Mean Time To Failure ◽  
The Mean ◽  
Mean Time

The ability of executing assigned function of repairable system under certain condition is quite different from that of single unit due to redundant configuration. It is well understood that proper management strategy can greatly prolong the mean time to failure (MTTF) of repairable system. By introducing operating cycle or partial test interval, repair time and maintenance efficiency, the MTTF of classic 1oo1, 1oo2 and 2oo3 redundant systems is studied in this paper. It is found that periodical maintenance can dramatically improve the availability of repairable system, while the efficiency of maintenance has great influence on the MTTF of repairable system.

scholarly journals Surveillance System in Smart Cities: A Dependability Evaluation Based on Stochastic Models

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 876
Author(s):  
Igor Gonçalves ◽  
Laécio Rodrigues ◽  
Francisco Airton Silva ◽  
Tuan Anh Nguyen ◽  
Dugki Min ◽  
...  
Keyword(s):  
Surveillance System ◽  
Smart Cities ◽  
Heterogeneous Data ◽  
Time To Failure ◽  
Video Streams ◽  
Dependability Evaluation ◽  
The Mean ◽  
Mean Time ◽  
The Internet Of Things

Surveillance monitoring systems are highly necessary, aiming to prevent many social problems in smart cities. The internet of things (IoT) nowadays offers a variety of technologies to capture and process massive and heterogeneous data. Due to the fact that (i) advanced analyses of video streams are performed on powerful recording devices; while (ii) surveillance monitoring services require high availability levels in the way that the service must remain connected, for example, to a connection network that offers higher speed than conventional connections; and that (iii) the trust-worthy dependability of a surveillance system depends on various factors, it is not easy to identify which components/devices in a system architecture have the most impact on the dependability for a specific surveillance system in smart cities. In this paper, we developed stochastic Petri net models for a surveillance monitoring system with regard to varying several parameters to obtain the highest dependability. Two main metrics of interest in the dependability of a surveillance system including reliability and availability were analyzed in a comprehensive manner. The analysis results show that the variation in the number of long-term evolution (LTE)-based stations contributes to a number of nines (#9s) increase in availability. The obtained results show that the variation of the mean time to failure (MTTF) of surveillance cameras exposes a high impact on the reliability of the system. The findings of this work have the potential of assisting system architects in planning more optimized systems in this field based on the proposed models.

On classes of life distributions based on the mean time to failure function

2021 ◽  
Vol 58 (2) ◽  
pp. 289-313
Author(s):  
Ruhul Ali Khan ◽  
Dhrubasish Bhattacharyya ◽  
Murari Mitra
Keyword(s):  
Damage Model ◽  
Replacement Policy ◽  
Time To Failure ◽  
Mean Time To Failure ◽  
Moment Convergence ◽  
Life Distributions ◽  
Cumulative Damage Model ◽  
The Mean ◽  
Age Replacement ◽  
Mean Time

AbstractThe performance and effectiveness of an age replacement policy can be assessed by its mean time to failure (MTTF) function. We develop shock model theory in different scenarios for classes of life distributions based on the MTTF function where the probabilities $\bar{P}_k$ of surviving the first k shocks are assumed to have discrete DMTTF, IMTTF and IDMTTF properties. The cumulative damage model of A-Hameed and Proschan [1] is studied in this context and analogous results are established. Weak convergence and moment convergence issues within the IDMTTF class of life distributions are explored. The preservation of the IDMTTF property under some basic reliability operations is also investigated. Finally we show that the intersection of IDMRL and IDMTTF classes contains the BFR family and establish results outlining the positions of various non-monotonic ageing classes in the hierarchy.

scholarly journals Effect of Grid Instability on Power Generation System's Reliability

2020 ◽  
pp. 27-37
Author(s):  
Joseph Benedict Bassey ◽  
Isaac F. Odesola
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Failure Rate ◽  
System Reliability ◽  
Power Distribution ◽  
Power Plants ◽  
Time To Failure ◽  
Generation System ◽  
Reliability Indices ◽  
Mean Time

Aims: Reliability assessment of power generation system may be performed with the concept of system adequacy, security or both. Grid being a major component in the power distribution chain is seen to have some influence on the state of the generation system reliability because of the perturbation that may arise from it. In this study, the generation system reliability is evaluated using both the system adequacy and security concept. Study Design: To capture the system security problems attributed to grid disturbance, the generation system is structured into two component systems (1 - generation component and 2 - transmission component) with a series arrangement. Methodology: The reliability indices such as, mean time to failure, mean time to repair, failure rate and repair rate are assessed on component bases and with respect to the entire generation system. Results: The effect of failure rate of the transmission component on the entire generation system failure rate was evaluated as 66.25%, 55.55%, 33.33%, 55.00% and 35.72% in year 2013, 2014, 2017 2018 and 2019 respectively for FIPL Power Plant and 52.94%, 82.35%, 61.38% and 100% effect was evaluated in the year 2016, 2017, 2018 and 2019 respectively for GT5 of Omoku Power Plant. Conclusion: These results showed that there is a significant influence of grid disturbances on the reliability state of the two gas turbine power plants in Nigeria. Measures on possible reliability state improvement of the power generation systems were suggested to include training and retraining of technical personnel on the management of major equipment in the generation and transmission stations. 

Điều trị tăng liều Imatinib trên bệnh nhân u mô đệm đường tiêu hoá giai đoạn muộn tiến triển sau điều trị bước 1 liều chuẩn

2020 ◽  
Author(s):  
Kien Do Hung
Keyword(s):  
Primary Tumor ◽  
Standard Dose ◽  
Performance Status ◽  
Gastric Tumor ◽  
High Dose ◽  
Time To Failure ◽  
Gastrointestinal Stromal Tumours ◽  
Mean Time To Failure ◽  
The Mean ◽  
Mean Time

Objective: Evaluating the result of high-dose imatinib for metastatic gastrointestinal stromal tumours after failure standard-dose first line. Patients and method: Restrospective analysis of 46 patients with metastatic gastrointestinal stromal tumours after failure standard-dose imatinib treated with high-dose imatinib at K hospital from 1/2015 đến 10/2019. Results: Median age was 54.6±9.5, male was 58.7%. The common primary tumor was gastric tumor. The mean time to failure of imatinib standard-dose 400mg/day was 38.2±5.3 months. Liver lesions were the most common lesions progressed after imatinib standard-dose failure (71.7%), primary tumor progressed was 39.1%. There was no patient who had complete response with treatment, the proportion of partial response accounted for 21.7% and stable disease was 45.7%. The clinical benefit rate was 67.4%. The sex-female, primary gastric tumor, good ECOG performance status, neutrophils, hemoglobine and albumin before treatment were the significant prognostic factors affecting the treatment response, p <0.05. The mean time to failure was 22.5 ± 3.4 (months), (min: 2.0; max: 58.0), median was 11.0 months. Conclusion: Treatment of high-dose imatinib after failure standard-dose 400mg/day showed the efficacy and good tolerance in metastatic GISTs.

scholarly journals On the estimation of the mean time to failure by simulation

2017 ◽  
Author(s):  
Peter W. Glynn ◽  
Marvin K. Nakayama ◽  
Bruno Tuffin
Keyword(s):  
Time To Failure ◽  
Mean Time To Failure ◽  
The Mean ◽  
Mean Time
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