scholarly journals Availability Equivalence Analysis of a Repairable Series-Parallel System

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Linmin Hu ◽  
Dequan Yue ◽  
Dongmei Zhao
Keyword(s):  
Parallel System ◽  
Failure Rates ◽  
Numerical Examples ◽  
Equivalence Factor ◽  
System Components ◽  
System Designs

This paper studies the availability equivalence of different designs of a repairable series-parallel system. Under the assumption that the system components have constant failure rates and repair rates, we derive the availability of the original and improved systems according to reduction, increase, hot duplication, warm duplication and cold duplication methods, respectively. The availability equivalence factor is introduced to compare different system designs. Two types of availability equivalence factors of the system are obtained. Numerical examples are provided to interpret how to utilize the obtained results.

scholarly journals Unavailability Analysis fork-out-of-n:G Systems with Multiple Failure Modes Based on Micro-Markov Models

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Shengjin Tang ◽  
Xiaosong Guo ◽  
Xiaoyan Sun ◽  
Haijian Xue ◽  
Zhaofa Zhou
Keyword(s):  
Failure Modes ◽  
Markov Models ◽  
Repairable System ◽  
Failure Rates ◽  
Multiple Failure Modes ◽  
Numerical Examples ◽  
Integrity Verification ◽  
Repair Mechanisms ◽  
Redundant Systems

Markov models are commonly used for unavailability analysis of redundant systems. However, due to the exploding states of Markov models for redundant systems, the states need to be merged to simplify the computation, which is called micro-Markov models. However, how to derive the failure rates and repair rates of the newly developed micro-Markov models has not been studied thoroughly. Therefore, this paper proposes detailed explanations and rules to derive the static unavailability by the micro-Markov models for thek-out-of-n:G systems with multiple failure modes. Firstly, two properties about applying the Markov models to the repairable system with independent multiple failure modes are presented. Based on these two properties, two rules are proposed for implementing the micro-Markov models. The micro-Markov models provide the exact same results for the repairablek-out-of-n:G system with multiple independent failure modes and repair mechanisms and approximate results for systems with multiple hybrid failure modes. A case study of safety integrity verification for safety instrumented systems is provided to illustrate the application of the proposed method. The conceptual comparison and numerical examples demonstrate the reasonability and usefulness of the proposed micro-Markov models.

Estimation of Individual Failure Rates for Power System Components Based on Risk Functions

2019 ◽  
Vol 34 (4) ◽  
pp. 1599-1607 ◽  
Author(s):  
Jan Henning Jurgensen ◽  
Lars Nordstrom ◽  
Patrik Hilber
Keyword(s):  
Power System ◽  
Failure Rates ◽  
Risk Functions ◽  
System Components

Redundancy Allocation for Serial-Parallel System Considering Heterogeneity of Components

2018 ◽  
Author(s):  
Zhicheng Zhu ◽  
Yisha Xiang ◽  
David Coit
Keyword(s):  
System Design ◽  
System Reliability ◽  
Raw Materials ◽  
Parallel System ◽  
Redundancy Allocation Problem ◽  
Redundancy Allocation ◽  
Numerical Examples ◽  
System Cost ◽  
The Impact ◽  
Cost Components

The redundancy allocation problem (RAP) for series-parallel system is a system design problem by selecting an appropriate number of components from multiple choices for desired objectives, such as maximizing system reliability, minimizing system cost. RAP has been extensively studied in the last decades. The majority of existing RAP models assume that components for selection are from homogeneous populations. However, due to manufacturing difficulties and variations in raw materials, many manufactured components/parts are heterogeneous, consisting of multiple subpopulations. In this research, we consider a typical RAP with the objective of maximizing the system reliability subject to the constraint of system cost. Components in each choice are assumed to be degradation-based, and each choice consists one normal subpopulation and several abnormal subpopulations. Numerical examples are investigated to illustrate the impact of the component heterogeneity.

scholarly journals Operational Reliability of the Rotary Cup Burner Type Saacke - SKV 60 of Marine Boiler

2013 ◽  
Vol 2 (1) ◽  
pp. 20-27
Author(s):  
Joško Dvornik ◽  
Srđan Dvornik
Keyword(s):  
Operational Reliability ◽  
Reliability Prediction ◽  
System Component ◽  
Steam Boiler ◽  
Failure Rates ◽  
Technical Literature ◽  
Starting Point ◽  
System Components ◽  
Two Factors ◽  
Basic Objective

One of the steps in predicting the reliability of a system includes determining the failure rate of the system’s components. The latter is obtained on the basis of the data available to the manufacturer, experience in using similar systems, using statistical methods and technical literature. In practice, the starting point in the process of foreseeing the reliability of any technical system is the assumption of constant failure rates. The system components’ failure rates which are determined in this way represent the so-called nominal values. This value is commonly modified by taking into account operation loads and environment conditions under which the observed system component is supposed to operate. In most cases the quantitative values of these two factors result from the engineering assessment that is based on the data available to the manufacturer or the user and takes into account the inevitable effect of a number of subjective factors. Predicting reliability is a process of determining numerical values which show the probability that machinery or engine will meet previously set requirements. The basic objective of reliability prediction is to ensure timely maintenance. This paper discusses predicting the operational reliability of the rotary cup burner type SAACKE - SKV 60 in the marine steam boiler TPK/VIC 8.5/7.

Motion Feasibility Framework for Remotely Operated Vehicles Based on Dynamic Positioning Capability

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Juan A. Ramírez-Macías ◽  
Rafael E. Vásquez ◽  
Asgeir J. Sørensen ◽  
Svein Sævik
Keyword(s):  
Steady State ◽  
Time Domain ◽  
Environmental Data ◽  
Specific Information ◽  
Dynamic Positioning ◽  
Remotely Operated Vehicle ◽  
Site Specific ◽  
Numerical Examples ◽  
Work Training ◽  
System Components

Abstract Knowing whether a remotely operated vehicle (ROV) is able to operate at certain foreknown environmental conditions is a question relevant to different actors during the vehicle’s life cycle: during design stages, buying an ROV, planning operations, and performing an operation. This work addresses a framework to assess motion feasibility in ROVs by using the concept of ROV-dynamic positioning capability (ROV-DPCap). Within the proposed framework, the ROV-DPCap number is defined to measure motion capability, and ROV-DPCap plots are used to illustrate results, for quasi-static standard (L2) and site-specific (L2s) conditions, and dynamic standard (L3) and site-specific (L3s) conditions. Data are computed by steady-state or time-domain simulations from the ROV model, depending on the desired analysis. To illustrate the use of the framework, numerical examples for L2 and L2s motion feasibility analyses for NTNU’s ROV Minerva are provided. Motion feasibility can be used to know whether an ROV is appropriately designed for a specific operation and choose the appropriate one for a certain need, for instance, when designing the DP system components or planning an operation from the environmental data and ROV-specific information. As expected, predictions can be improved when more detailed information about the ROV appears; the same framework can be used to provide more detailed answers to motion feasibility-related questions. The results are likely to be straightforwardly understood by people whose work/training is ROV related and can interpret the graphic results for different operation scenarios.

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