Reliability Allocation Model Research Articles

Reliability-centered availability collaborative optimization allocation approach for machine tools

The availability of computer numerical control (CNC) machine tools is a comprehensive reflection of reliability and maintainability. To ensure the availability requirements of products, it is necessary to allocate the availability indicators of the entire machine to all units. Traditional methods based on reliability allocation or maintainability allocation ignore the coupling relationships among them, which cannot comprehensively improve the availability level of machine tools. Therefore, in this paper, a availability collaborative optimization allocation model for CNC machine tools is proposed to maximize the availability under the optimal combination of failure rate and repair rate. Firstly, a two-stage reliability allocation model based on different allocation mechanisms is established by taking the Function-Motion-Action (FMA) decomposition tree as the allocation path. In the first stage, the allocation weights are determined based on global sensitivity analysis. In the second stage, the reliability optimization allocation model based on Copula function is established. Then, with reliability as the center, an availability collaborative optimization allocation model constrained by maintainability is constructed, and the non-dominated sorting genetic algorithm II (NSGA-II) algorithm is used to solve the model. Finally, a CNC gear milling machine is taken as an example to verify the rationality and effectiveness of the method on product availability requirements under collaborative allocation.

Time‐constrained and reliability aware energy minimization scheduling algorithm for heterogeneous multiprocessor environments

SummaryHeterogeneous multiprocessor systems are now widely used in industry by providing high performance and high concurrency. However, with the increasing number of computational nodes, it leads to a dramatic increase in energy consumption of heterogeneous multiprocessor systems. Most of the current research has been conducted to reduce the energy consumption by reducing the processor frequency and extending the task execution time, but these measures often lead to a significant decrease in system reliability. This article addresses the problem of energy‐aware task scheduling in the case of distributed computing systems with deadline and reliability constraints. First, a time and reliability allocation model is built to assign the deadline and reliability constraints to each task, which ensures fairness among tasks. Then, a three‐stage scheduling algorithm is proposed to minimize the system energy consumption. The static energy consumption is minimized by shutting down the inefficient processors. The dynamic energy consumption of the system is reduced by distributing tasks as evenly as possible on each processor through a task redistribution strategy. Finally, experimental results on real scientific workflows and randomly generated graphs show that the proposed algorithm outperforms other algorithms in terms of energy reduction.

Research on the Reliability Allocation Method of Smart Meters Based on DEA and DBN

Reliability allocation can reasonably determine the reliability index of each unit in the system to ensure product quality in design, manufacturing, testing and acceptance. In the design process of the smart meter, the preliminary reliability allocation results may be unreasonable, so in the middle and later stages of the design stage, the reliability needs to be reallocated. The traditional allocation method has some limitations, such as strong subjectivity, large amount of calculation and too much reliance on expert judgment. In order to solve these problems, this paper presents a multi-method fusion method of reliability allocation. First, this paper uses the goal-oriented methodology (GO methodology) to integrate dynamic Bayesian networks (DBNs) to predict the reliability of smart meters. Second, a data envelopment analysis (DEA) reliability allocation model is established, the posterior probability obtained by DBN reasoning together with the failure rate and structural complexity of each unit are used as the output indicators of this model. Finally, the reliability allocation weight is calculated by using the efficiency value obtained from the DEA reliability allocation model. The validity and accuracy of this method is verified by an accelerated life test. This provides a new idea for reliability reallocation of smart meters.

Reliability-based design optimization approach for compressor disc with multiple correlated failure modes

In this work, a reliability optimization method is proposed to resolve the multi-objective reliability-based design optimization (MORBDO) of the compressor disc with multiple correlated failure modes. The cost function-based reliability allocation model is firstly established to allocate the structural reliability into reliability under failure mode by minimizing the cost. During this process, the correlations among multi-failure modes are described by using the pair-copula function. Then, an improved MOPSO algorithm based on the niche sorting strategy and the dynamic inertia weight, is employed to solve the MORBDO problem while guaranteeing efficiency and accuracy. The proposed approach is verified by the MORBDO of the compressor disc considering low cycle fatigue (LCF), creep-fatigue (CF), and combined high and low cycle fatigue (H-LCF) failure modes. Strong non-linear positive correlations among the lifetimes of three failure modes are revealed. It is proved that ignoring the correlations among failure modes by assuming independent failure modes will result in an overly conservative reliability prediction, thus leading to redundancy of structural performance in MORBDO. Furthermore, the results proved that the improved MOPSO algorithm does not only provide a better Pareto front curve but also improves computational efficiency.

Research on the Reliability Allocation Method for a Wind Turbine Generator System Based on a Fuzzy Analytic Hierarchy Process Considering Multiple Factors

Given the current reliability allocation problem of wind turbine generator systems, based on the reliability allocation method of series systems, a reliability allocation model based on an improved fuzzy analytic hierarchy process (FAHP) is proposed. A three-scale standard is adopted to comprehensively consider six influencing factors, such as technical level, working environment and importance, by determining the comprehensive allocation weight combined with an improved FAHP and entropy weight method. In this way, the reliability allocation calculation model for a wind turbine generator system is developed for the reliability allocation of the wind turbine generator system. Using the method developed in this study and other methods for the reliability allocation of a wind turbine generator system as examples, the allocation results are compared and analyzed. The results show that this method not only is effective but also obtains lower allocation results than those of other studies, which verifies the rationality of the present method.

Intuitionistic Fuzzy AHP based Reliability Allocation Model for Multi-Software System

It is a challenge for developers to attain the desirable reliability for a software system considering the users and development team's requirements simultaneously. In our present work, we have inc...

Intuitionistic fuzzy AHP based reliability allocation model for multi-software system

Intuitionistic fuzzy AHP based reliability allocation model for multi-software system

A reliability allocation method of mechanism considering system performance reliability

AbstractIt is generally believed that the reliability of a mechanical system is determined by its composition. The system operates properly when all of its components do not fail. Based on this assumption, the reliability of the system can be represented by the reliability of its components. A problem arises when applying this hypothesis to a system containing motion mechanisms. There is a phenomenon in motion mechanism that the components do not happen structural failure (we call it “Type I failure”) and joint failure (we call it “Type II failure”), but the function of the mechanism cannot meet the requirements (we call it “Type III failure”). A reliability allocation method, which synthetically considers the composition and Type III failure modes of the motion mechanism, is proposed to solve this problem. A relative dispersion factor is introduced to describe the failure dependence of components and is proposed to calculate the complexity and criticality. A series system reliability allocation model considering three types of failure modes is established. Finally, using an airplane gear door lock mechanism as an example, a comparative analysis of the system reliability allocation results with and without considering Type III failure modes is made. The allocation results show the component reliability value without considering Type III failure modes is less than that when considering them, which will increase the system hazards. The result considering Type III failure modes is more reasonable than that from the traditional method.

Reliability allocation model and algorithm for phased mission systems with uncertain component parameters based on importance measure

This paper presents a model to deal with reliability allocation problem of phased mission systems (PMS), especially for PMS with uncertainty in components’ parameters due to inaccurate information and different phase environments. In practice, real value of the reliability of a component may become lower than its designed value due to such uncertainty, thus making the whole system fail to meet the required reliability level. Therefore, in this paper, we present a model that incorporates the component uncertainty in the system reliability allocation process and then propose a variance-based global importance hybrid heuristic algorithm for its solution. The variance-based global importance measure is used to evaluate the importance of a component to the mission reliability of PMS while the reliabilities of all components vary randomly. The main procedures of the proposed algorithm include: (1) generate feasible solutions by roulette wheel selection method based on a global importance index; (2) improve solutions by adjusting reliability parameter values of components according to their global importance; and (3) improve solutions by crossover and mutation operations of genetic algorithm (GA). To illustrate the effectiveness of the proposed model and algorithm, two examples of PMS are presented and the allocation solutions are validated through Monte–Carlo simulation method. Finally, we compare the proposed model with a general allocation model that does not consider component uncertainty, and additionally with a cost-based heuristic algorithm and a particle swarm optimization (PSO) algorithm. Our results show that component uncertainty has significant influence on the confidence level that an allocation solution satisfies the required system reliability. Hence, it is essential to consider component uncertainty in reliability allocation process. In comparison with the cost heuristic algorithm and the PSO algorithm, the proposed algorithm is more effective in reliability allocation of PMS with uncertainty in components’ parameters.

Optimal Reliability Allocation of ±800 kV Ultra HVDC Transmission Systems

In this paper, an optimal reliability allocation (ORA) model of ±800 kV ultra-high voltage direct current (HVDC) transmission system is proposed. The model intends to provide the means to determine the availability requirements of components in the bidding process of ±800 kV ultra HVDC transmission projects. In this model, the component availability is optimized based on the prespecified system reliability. The objective function is composed of the component investment cost and the operation and maintenance cost. The ORA is formulated as a constrained nonlinear programming problem, and the genetic algorithm (GA) is used to find its solution. An improved dagger sampling (IDS) method is proposed to evaluate the reliability of ultra HVDC systems, and a bisection method is used to generate the initial population of the GA. An actual ultra HVDC project is used to conduct the case study. Results show that the proposed ORA model can minimize the component investment, operation, and maintenance costs, while achieving optimal allocation of the system reliability index to obtain the availability of components. In addition, the impact of the component spare on the ORA result is investigated. Performance comparison on the sampling efficiency of the IDS method and the direct Monte Carlo sampling method is also presented.

A-IFM reliability allocation model based on multicriteria approach

Purpose The paper aims to evaluate reliability allocation using an aerospace system prototype. The proposed approach has been applied and compared with other traditional methods on an aerospace system prototype, where the reliability allocation process is rigorous. Design/methodology/approach The new approach is based on Integrated factors Method (IFM), whose values are adjusted trough a multicriteria method, the Analytic Hierarchy Process, depending on the importance of each factor and each unit of the system. The result is a dynamic model, that combines the advantages of the allocation method and the multicriteria decision-making technique. Findings The reasons that led to the development of the IFM based AHP are the outcome of a careful analysis of the current military and commercial approaches. In particular most of analyzed methods use constant weights for the factors involved in the reliability allocation; different weights are rarely assigned to these factors. Research limitations/implications There is no limitation for implementation of A-IFM reliability allocation model in very large and complex systems, and it can therefore provide an improved structured arrangement for reliability allocation. Therefore, researchers are encouraged to test the proposed propositions further. Practical implications The proposed method offers several benefits compared with current military and commercial approaches. Originality/value The computational results clearly demonstrate the effectiveness of the new approach and its ability to overcome the criticalities highlighted in literature.

A nonparametric approach for optimal reliability allocation in health services

Purpose – Reliability evaluation of healthcare services has been a challenging task for both operations managers and system engineers working in the respective field. The purpose of this paper is to develop a data envelopment analysis-based reliability allocation model. Design/methodology/approach – A two-phase optimization scheme for the reliability evaluation and allocation of homogeneous system entities, namely, hospitals, operating in a healthcare network is proposed. First, reliability evaluation is performed nonparametrically through the frontier estimation technique data envelopment analysis by considering several failure modes and failure free discharged patients as the inputs and output of the service system. Subsequently, optimal reliability allocation that maximizes the overall network reliability subject to a budget constraint is carried out by utilizing weights of the inputs and output calculated on the Pareto optimal frontier, which is constructed from the most reliable hospitals operating in the network. Findings – The popular performance assessment methodology DEA is found to be an invaluable reliability assessment and allocation tool, where optimal weights of the associated envelopment model, under certain budget restrictions, are used to maximize overall network reliability. Originality/value – An empirical illustration of the proposed model is presented on a set of hospital network data from Turkey. Modeling implications can be carried out on similar service operations where identification of the critical performance indicator costs is possible.

Reliability Analysis of CNC Machine Tools Based on Fuzzy Theory

There are many factors influencing the reliability allocation of CNC machine tools and some are difficult to analyze quantitatively, a comprehensive reliability allocation method is proposed using interval analysis, fuzzy comprehensive evaluation and analytic hierarchy process. Many influence factors were considered and endowed with different weight respectively according to the influence degree. In this paper, a reliability allocation model is proposed for CNC machine tools, which used interval number instead of real number to express uncertain information. It could make use of the field test information and experts’ experience comprehensively. Finally, the application of this method is illustrated with an example, and the results showed that the allocation method is feasible and effective for the reliability allocation of CNC machine tools.

Fuzzy multi-objective software reliability redundancy allocation based on swarm intelligence algorithm

A fuzzy multi-objective software reliability allocation model was established,and bacteria foraging optimization algorithm based on estimation of distribution was proposed to solve software reliability redundancy allocation problem.As the fuzzy target function,software reliability and cost were regarded as triangular fuzzy members,and bacterial foraging algorithm optimization based on Gauss distribution was applied.Different membership function parameters were set up,and different Pareto optimal solutions could be obtained.The experimental results show that the proposed swarm intelligence algorithm can solve multi-objective software reliability allocation effectively and correctly,Pareto optimal solution can help the decision between software reliability and cost.

A structure-based software reliability allocation using fuzzy analytic hierarchy process

During the design phase of a software, it is often required to evaluate the reliability of the software system. At this stage of development, one crucial question arises ‘how to achieve a target reliability of the software?’ Reliability allocation methods can be used to set reliability goals for individual components. In this paper, a software reliability allocation model has been proposed incorporating the user view point about various functions of a software. Proposed reliability allocation method attempts to answer the question ‘how reliable should the system components be?' The proposed model will be useful for determining the reliability goal at the planning and design phase of a software project, hence making reliability a singular measure for performance evaluation. Proposed model requires a systematic formulation of user requirements and preference into the technical design and reliability of the software. To accomplish this task, a system hierarchy has been established, which combines the user’s view of the system with that of the software manager and the programmer. Fuzzy analytic hierarchy process (FAHP) has been used to derive the required model parameters from the hierarchy. Sensitivity analysis has also been carried out in this paper. Finally, an example has been given to illustrate the effectiveness and feasibility of the proposed method.

Safety reliability optimal allocation of food cold chain

This paper applied the safety reliability of food cold chain logistics to establish reliability allocation model for cold chain systems, designed optimization algorithms, and made a case analysis. By applying system reliability allocation principle, this article firstly built safety reliability allocation model of food cold chain logistics system without cost constraint based on the safety reliability model of food cold chain logistics system, and then it set up optimal decision- making model of food cold chain logistics system with cost constraint using the functional relationship between the time, temperature of cold chain logistics and logistics costs. Next, according to the characteristics of the model, a heuristic algorithm was proposed to allocate safety reliability of the system to each cold chain unit so as to achieve the goal of operatingcosts optimization subject to assurance ofoverall safety reliability of the cold chain system. Taking the safety impact factor of food cold chain unit as a weight, the article also deduced the equation of reallocation of safety reliability of food cold chain system. In the end, these models were used to optimize the allocation of safety reliability in an example of Sushi cold chain process. It provided a new thought and method to optimally plan the unit safety of food cold chain system as well as reduce the cost of food cold chain.

Fuzzy Multi-Objective Software Reliability Redundancy Allocation Based on MEDA-BFA Algorithm

Software reliability allocation problem is a major problem in engineering design practices. A fuzzy multi-objective software reliability allocation model is established by analyzing the software redundancy architecture and considering some fuzzy factors to reliability. Then, the MEDA-BFA algorithm is proposed based on estimation of distribution to solve software reliability redundancy allocation problem. Finally, experimental results show that the proposed intelligence algorithm can solve multi-objective software reliability allocation effectively and correctly, can help decision makers decide between software reliability and cost.

Real-Time Reliability Analysis and Optimal Distribution of the Reliability on Five-Axis Machining Center

The some five-axis machining center was investigated, and it divided ten subsystems. Based on analysis of fault data, the distribution of fault time submits to Weibull distribution, the distribution function and reliability function of each subsystem were confirmed. The reliability allocation model with the constraints of cost is established based on reliability prediction to get optimal reliability allocation results of the complicated mechano-electronic system. The most growth potential of the reliability of subsystem and growth situation of reliability of each subsystem could be got by using this method. The reliability allocation is an important part of reliability design, because its result influences system design directly. This provides reference for design improving of this series of new products.

Software Reliability and Testing Time Allocation: An Architecture-Based Approach

With software systems increasingly being employed in critical contexts, assuring high reliability levels for large, complex systems can incur huge verification costs. Existing standards usually assign predefined risk levels to components in the design phase, to provide some guidelines for the verification. It is a rough-grained assignment that does not consider the costs and does not provide sufficient modeling basis to let engineers quantitatively optimize resources usage. Software reliability allocation models partially address such issues, but they usually make so many assumptions on the input parameters that their application is difficult in practice. In this paper, we try to reduce this gap, proposing a reliability and testing resources allocation model that is able to provide solutions at various levels of detail, depending upon the information the engineer has about the system. The model aims to quantitatively identify the most critical components of software architecture in order to best assign the testing resources to them. A tool for the solution of the model is also developed. The model is applied to an empirical case study, a program developed for the European Space Agency, to verify model's prediction abilities and evaluate the impact of the parameter estimation errors on the prediction accuracy.

Reliability Allocation Model of Weapon System Through Total Life Cycle Cost

Reliability Allocation Model of Weapon System Through Total Life Cycle Cost