RAMS技术在动车组电气连接器中的应用

在动车组电气连接器中引入RAMS技术,针对新型动车组自动电气连接器,建立系统可靠性模型,进行可靠性分配、预计,计算出系统的MTBF时间;基于系统的故障树分析,对系统的顶事件的影响进行安全性分析、评估;根据用户要求及相关标准(EN 50126),定义了系统各单元的危险事件、危险源、危险的严重性及可能性,依据风险矩阵进行系统的风险评估。     

汽车零部件可重构自动化制造系统的研究

针对按传统理论设计制造的汽车零部件自动生产线只适合单一品种加工、设计制造周期长、零部件通用化率低、成本高的缺点,通过对汽车零部件可重构自动化制造系统的特点及其关键技术的研究和探讨,提出了一种新型的汽车零部件可重构自动化制造系统(RAMS)模式,并以此为技术平台,研制了一条可重构、短流程、柔性化的活塞自动生产线,实现了活塞加工高效率、高精度、高质量、低成本的生产需求。通过分析进一步指出:可重构自动化制造系统是现代先进制造技术的集成和再造,将成为支持21世纪初全球制造业发展的重大技术。     

Numerical Simulation of Fluxes Generated by Inhomogeneities of the Underlying Surface over the Jinta Oasis in Northwestern China

Using land-use types derived from satellite remote sensing data collected by the EOS Moderate Resolution Imaging Spectroradiometer (EOS/MODIS),the mesoscale and turbulent fluxes generated by inhomogeneities of the underlying surface over the Jinta Oasis,northwestern China,were simulated using the Regional Atmospheric Modeling System (RAMS4.4).The results indicate that mesoscale circulation generated by land-surface inhomogeneities over the Jinta Oasis is more important than turbulence.Vertical heat fluxes and water vapor are transported to higher levels by mesoscale circulation.Mesoscale circulation also produces mesoscale synoptic systems and prevents water vapor over the oasis from running off.Mesoscale circulation transports moisture to higher atmospheric levels as the land-surface moisture over the oasis increases,favoring the formation of clouds,which sometimes leads to rainfall.Large-scale wind speed has a significant impact on mesoscale heat fluxes.During the active phase of mesoscale circulation,the stronger large-scale winds are associated with small mesoscale fluxes; however,background wind seems to intensify the turbulent sensible heat flux and turbulent latent heat flux.If the area of oasis is enlarged properly,mesoscale circulation will be able to transport moisture to higher levels,favoring the formation of rainfall in the oasis and protecting its "cold island" effect.The impact of irrigation on rainfall is important,and increasing irrigation across the oasis is necessary to protect the oasis.     

Reliability, availability and maintenance optimisation of heat exchanger networks

A new methodology is proposed to use comprehensive up-to-date commercial software tools for heat exchanger network (HEN) reliability modelling and optimisation. The idea behind this proposal is that to apply the combination of specific HEN optimisation and reliability software packages has several advantages over the commonly used approach. There is a variety of features that need to be taken into account to choose the right software tool. The HEN design has a significant impact on reliability issues and this should be considered. There are many related issues and features – the robustness, the type of welding, the increment of maximum mechanical resistance, the impact on manufacturing costs, reduction of lost opportunity costs caused by exchanger outages, troubleshooting of heating exchanger problems by operators etc. Fouling should be analysed as it has a significant impact on maintenance issues. Up to 30% decrease of maintenance costs can be achieved annually by applying advanced reliability results and determining heat exchanger failure causes. These analyses include the investigation of failure causes, prediction of future probabilities of failures, cleaning planning and scheduling and the calculation of reliability and maintainability.     

Integrating RAMS engineering and management with the safety life cycle of IEC 61508

This article outlines a new approach to reliability, availability, maintainability, and safety (RAMS) engineering and management. The new approach covers all phases of the new product development process and is aimed at producers of complex products like safety instrumented systems (SIS). The article discusses main RAMS requirements to a SIS and presents these requirements in a holistic perspective. The approach is based on a new life cycle model for product development and integrates this model into the safety life cycle of IEC 61508. A high integrity pressure protection system (HIPPS) for an offshore oil and gas application is used to illustrate the approach.     

RAMS+C informed decision-making with application to multi-objective optimization of technical specifications and maintenance using genetic algorithms

The role of technical specifications and maintenance (TSM) activities at nuclear power plants (NPP) aims to increase reliability, availability and maintainability (RAM) of Safety-Related Equipment, which, in turn, must yield to an improved level of plant safety. However, more resources (e.g. costs, task force, etc.) have to be assigned in above areas to achieve better scores in reliability, availability, maintainability and safety (RAMS). Current situation at NPP shows different programs implemented at the plant that aim to the improvement of particular TSM-related parameters where the decision-making process is based on the assessment of the impact of the change proposed on a subgroup of RAMS+C attributes.This paper briefly reviews the role of TSM and two main groups of improvement programs at NPP, which suggest the convenience of considering the approach proposed in this paper for the Integrated Multi-Criteria Decision-Making on changes to TSM-related parameters based on RAMS+C criteria as a whole, as it can be seem as a decision-making process more consistent with the role and synergic effects of TSM and the objectives and goals of current improvement programs at NPP. The case of application to the Emergency Diesel Generator system demonstrates the viability and significance of the proposed approach for the Multi-objective Optimization of TSM-related parameters using a Genetic Algorithm.     

Reliability allocation methods: A systematic literature review

The choice of a reliability allocation method is not always easy or straightforward, since it depends on several factors. Some factors are directly related to the characteristics of the analyzed system, such as the level of complexity or the reliability configuration; on the other hand, additional aspects constitute boundary conditions, such as budget or experimentation time. In this scenario, the purpose of the present research is to present a systematic literature review on reliability allocation, proposing a guideline to choose the optimal allocation method in respect to the desired application, available resources, and required accuracy. The proposed review analyzes allocation methods in literature, determining main features and area of application. Motivated by a lack of a comprehensive methods summarization present in literature, our research goal is to assist practitioners in choosing a well-suited method and to provide an overview, to support academics in conducting new research in this area. The results of the performed analysis are synthetized according to several criteria. The results are summarized and categorized in different clusters for each individuated application field. The proposed summarization design allows an easy and rapid consultation.     

Alternatives and challenges in optimizing industrial safety using genetic algorithms

Safety (S) improvement of industrial installations leans on the optimal allocation of designs that use more reliable equipment and testing and maintenance activities to assure a high level of reliability, availability and maintainability (RAM) for their safety-related systems. However, this also requires assigning a certain amount of resources (C) that are usually limited. Therefore, the decision-maker in this context faces in general a multiple-objective optimization problem (MOP) based on RAMS+C criteria where the parameters of design, testing and maintenance act as decision variables. Solutions to the MOP can be obtained by solving the problem directly, or by transforming it into several single-objective problems. A general framework for such MOP based on RAMS+C criteria is proposed in this paper. Then, problem formulation and fundamentals of two major groups of resolution alternatives are presented. Next, both alternatives are implemented in this paper using genetic algorithms (GAs), named single-objective GA and multi-objective GA, respectively, which are then used in the case of application to solve the problem of testing and maintenance optimization based on unavailability and cost criteria. The results show the capabilities and limitations of both approaches. Based on them, future challenges are identified in this field and guidelines provided for further research.     

Use of multiple objective evolutionary algorithms in optimizing surveillance requirements

This paper presents the development and application of a double-loop Multiple Objective Evolutionary Algorithm that uses a Multiple Objective Genetic Algorithm to perform the simultaneous optimization of periodic Test Intervals (TI) and Test Planning (TP). It takes into account the time-dependent effect of TP performed on stand-by safety-related equipment. TI and TP are part of the Surveillance Requirements within Technical Specifications at Nuclear Power Plants. It addresses the problem of multi-objective optimization in the space of dependable variables, i.e. TI and TP, using a novel flexible structure of the optimization algorithm. Lessons learnt from the cases of application of the methodology to optimize TI and TP for the High-Pressure Injection System are given. The results show that the double-loop Multiple Objective Evolutionary Algorithm is able to find the Pareto set of solutions that represents a surface of non-dominated solutions that satisfy all the constraints imposed on the objective functions and decision variables. Decision makers can adopt then the best solution found depending on their particular preference, e.g. minimum cost, minimum unavailability.     

Risk assessment techniques for civil aviation security

Following the 9/11 terrorists attacks in New York a strong economical effort was made to improve and adapt aviation security, both in infrastructures as in airplanes. National and international guidelines were promptly developed with the objective of creating a security management system able to supervise the identification of risks and the definition and optimization of control measures.Risk assessment techniques are thus crucial in the above process, since an incorrect risk identification and quantification can strongly affect both the security level as the investments needed to reach it.The paper proposes a set of methodologies to qualitatively and quantitatively assess the risk in the security of civil aviation and the risk assessment process based on the threats, criticality and vulnerabilities concepts, highlighting their correlation in determining the level of risk.RAMS techniques are applied to the airport security system in order to analyze the protection equipment for critical facilities located in air-side, allowing also the estimation of the importance of the security improving measures vs. their effectiveness.