Proportional hazards modelling of aircraft cargo door complaints

Proportional hazards modelling is a powerful technique which can be used to investigate the effects of various explanatory variables on the life length of equipment. In this paper the analysis of aircraft cargo door complaints is considered, as this can cause serious delay problems. Particular attention is given to the assumptions supporting the application of the model. Consideration is given to problems in the choice of the appropriate basic metric time, definition of covariates and adapting the methodologies to this particular problem. Emphasis is placed upon the validation of the results by attempting several different structures of the dependent variables.     

An optimal design of solar water heating systems

Abstract

Based on the seismicity and tectonics of Taiwan area, a set of potential earthquake sources is identified. Using available attenuation laws and fault‐rupture model, the individual influences of potential sources are integrated into the probability distribution of maximum annual intensity and peak acceleration. The results are presented in the form of seismic risk maps for a 475‐year return period. Based on the result of this study, it concludes that the seismic hazard potential for the central region is moderate, but it is high for east‐coast region.

This paper also presents a reliability analysis method for safety evaluation of buried pipelines in Taiwan region. The results of the reliability analysis of the buried pipelines subjected to earthquake ground accelerations are presented and a fragility result for peak ground acceleration (PGA) studies is also constructed.     

Application of the weibull proportional hazards model to aircraft and marine engine failure data

The environment in which an equipment operates and associated diagnostic variables, such as metal particle level in engine oil, are factors that can influence an equipment's failure time. These factors can be incorporated into concomitant variable models such as the proportional hazards model (PHM), which has been widely used in medical research but not in engineering reliability. A Weibull PHM is applied to both aircraft engine failure data and marine gas turbine failure data. Examination of the residuals shows a good fit of the Weibull proportional hazards model to the data.     

长江三峡库区水库诱发地震的研究

中国长江三峡工程于2003年6月1日正式下闸蓄水，6月7日起突然在湖北省巴东县城北信陵镇沿江一线发生了2000多次密集的小震群，引起了大家的严重关切，在未来的几年内随着二期和三期工程的完工，水位将提高到156m和175m，是否会诱发更大更强的地震？根据地震构造的观点分析了库区东段几条活动断裂的分布、交汇关系和孕震能力，认为巴东和秭归可能为两个潜在震源区，蓄水后有引发5.5级左右的地震可能，地震烈度可达VII°~VIII°；并可能诱发库区内众多滑坡体的复活，导致严重的地质灾害。     

中国抗震鉴定加固五十年回顾与展望

在中国地震灾害预测的理论、技术和实践已经有40年的历史,由于政府、社会和公众对防灾减灾意识的逐渐增强,该学科得到了较为广泛的应用,使其成长为地震工程领域比较受关注的学科之一。该文拟从时间节点维度和政府、社会和公众应用的视角阐述其沿革、发展和应用延伸的历程。总体来说,震害预测的发展过程是按照以下的脉络延展的：初期只是针对典型区域内几类建(构)筑物的单体,目的是找出不同类型结构抗震的薄弱环节,为其减灾和加固提供基础依据;而后,重点转向了工作区域内不同结构的群体抗震能力和可能造成的损失及人员伤亡的分布,目标放到了城市、区域的规划、防灾准备和震时的应急评估;近十余年,保险业为了厘定保额和赔率,推动了群体震害预测和灾害风险评估工作;目前,由于政府的大量投入和指导,并分类推进全社会的灾害风险评估和治理,使得震害预测工作迎来了新的发展契机。随着不同的发展阶段,震害预测理论和方法的研究都得到了逐步完善、深化和延伸。该文仅从一个侧面概述了震害预测发展历程,难免挂一漏万和出现评论上谬误,供本行业从业人员讨论。     

Application of land-use planning criteria for the control of major accident hazards: a case-study

Land-use planning (LUP) with respect to major accident hazards is one of the more important requirements of Directive 96/82/EC (the so-called Seveso II Directive). Different approaches were developed by the Member States of the European Union in order to implement this aspect of the Directive. This study focuses on the comparison of the specific approaches developed for LUP with respect to major accidents hazards. An Italian industrial area has been selected to perform a case study. The different LUP criteria have been used both to evaluate the present state of the area and the effect of several proposed hazard reduction actions. The results obtained have allowed a comparison of the different LUP methodologies. Critical steps in the application of the different LUP criteria have been identified, and the different priorities of hazard reduction actions resulting from risk-based and consequence-based approaches have been highlighted.     

汶川地震百花大桥震害分析

以在汶川地震中遭到严重破坏的百花大桥为研究对象,结合其震害建立了考虑墩柱、系梁、板式橡胶支座、钢筋混凝土挡块、伸缩缝和桥台等构件非线性力学性能的数值模型,采用距桥址最近的卧龙台记录,使用增量动力分析法（IDA）对其进行分析,结果表明：18跨牛腿搭接长度偏小是直接导致5联发生整体倒塌的原因,而不合理的支座布置方式导致双柱式固定墩无法共同受力,使一侧桥墩过早发生严重损伤从而无法为主梁提供足够的纵向约束也是不可忽视因素。     

Aviation software and hardware diagnostic unit for monitoring cross-country gas pipelines

The main components of a software and hardware diagnostic unit that makes it possible to perform remote laser probing of cross-country gas pipelines from on board an aircraft are considered. Results are provided for flying tests of the unit for a simulated gas leakage processed using special software. Translated from Izmeritel’naya Tekhnika, No. 2. pp. 41–44, February, 2009.     

Reliability assessment for systems suffering common cause failure based on Bayesian networks and proportional hazards model

The Bayesian network (BN) is an efficient tool for probabilistic modeling and causal inference, and it has gained considerable attentions in the field of reliability assessment. The common cause failure (CCF) is simultaneous failure of multiple elements in a system under a common cause, and it is a common phenomenon in engineering systems with dependent elements. Several models and methods have been proposed for modeling and assessment of complex systems with CCF. In this paper, a new reliability assessment method is proposed for the systems suffering from CCF in a dynamic environment. The CCF among components is characterized by a BN, which allows for bidirectional reasoning. A proportional hazards model is applied to capture the dynamic working environment of components and then the reliability function of the system is obtained. The proposed method is validated through an illustrative example, and some comparative studies are also presented.     

第二代基于性能地震工程中的地震易损性模型及正逆概率风险分析

第二代基于性能地震工程理论中的地震易损性主要是指结构构件以及非结构构件的抗震能力,与传统地震风险理论中的地震易损性定义和内涵并不相同。为了澄清二者的不一致性,首先介绍传统地震风险理论中地震易损性的定义和概率模型,然后指出第二代基于性能地震工程理论存在五个层次的地震易损性模型：地震需求易损性模型、抗震能力易损性模型、地震损伤易损性模型、地震损失易损性模型和抗震决策易损性模型,指出了这五种模型的区别及其相互关系,推导得到了地震需求易损性模型和地震损伤易损性模型分布参数的解析表达式。在此基础上,根据不同的不确定性传递路径,提出了正向PBEE和逆向PBEE的概念,以通过不同方式求解第二代基于性能地震工程理论的风险积分公式。基于地震危险性函数的近似表达式以及地震易损性模型及其分布参数的解析表达式,通过正向PBEE和逆向PBEE方法,分别得到了具有相同表达形式的工程需求参数EDP、地震损伤DM和决策变量DV三个层次的概率地震风险表达式。通过该文的研究,将传统地震风险分析理论与第二代基于性能地震工程理论统一在一致的理论框架之中。     

中国地震区划图应用和工程抗震

介绍了中国地震活动概况,中国地震区划图使用的内涵和抗震设防准则,提出了大型水工建筑、跨海大桥、长输油气管线、核电厂、石化厂等可能导致产生严重次生灾害场地进行地震安全性评价;以地震实例简要讨论了地震崩塌、滑坡、砂土液化、地震断层等地震地质灾害及抗震对策。     

Optimal design base shear forces for reinforced concrete buildings considering seismic reliability and life-cycle costs

The objective of this study is to propose a novel estimation procedure for optimal design base shear forces for reinforced concrete (RC) buildings while considering the seismic reliability and life-cycle costs (LCCs) incurred by life-cycle earthquake events. By simulating life-cycle earthquake events within a specified period and using nonlinear dynamic analysis, including earthquake occurrences and their peak ground accelerations (PGAs), this study also derives the damage states of an RC building considering the effect of the cumulative damage. Additionally, besides life-cycle earthquake events, a simplified model is developed to modify the structural properties of a structure without seismic repair after earthquakes. Given the uncertainty of the occurrence time and PGAs of earthquake events, the seismic reliability, and expected current values of LCCs are calculated using Monte Carlo simulation. Although the case study addresses only an RC building with five stories in Taipei, optimal design base shear forces for low-rise RC buildings calculated via the same procedure can be derived and utilized when making decisions on the seismic level of a building based on safety and economic considerations. Therefore, the proposed method can help both owners and investors to identify LCCs of RC buildings due to seismic structural damage within a specified service life.     

中国震害预测工作的沿革与发展

在中国地震灾害预测的理论、技术和实践已经有40年的历史,由于政府、社会和公众对防灾减灾意识的逐渐增强,该学科得到了较为广泛的应用,使其成长为地震工程领域比较受关注的学科之一.该文拟从时间节点维度和政府、社会和公众应用的视角阐述其沿革、发展和应用延伸的历程.总体来说,震害预测的发展过程是按照以下的脉络延展的:初期只是针对...     

厦金大桥地区地震危险性远景探讨

厦门—金门及其邻近地区的现代地震特征虽已有讨论，但是自1999年9月21日台湾西部集集发生大地震(M=7.3)之后，促使人们考虑厦金地区在未来大桥工程修成之后的长期运转过程中，是否有更大地震发生而受到波及?这就需要从厦金地区周边更大的区域来进行分析。文章试图从台湾海峡地震内部成因、大陆福建沿岸的地震和台湾造山带内经常发生的较大地震可能对本区造成的危害进行探讨。     

Proportional hazards modelling of repairable systems

The purpose of this paper is to illustrate some situations under which the proportional hazards model (PHM) and its extensions can be used for identification of the most important covariates influencing a repairable system. First of all an overview of the application of the PHM in engineering is presented. Then the concepts of the PHM and its extensions, such as stratified PHM, PHM in the case of non-homogeneous Poisson processes and PHM in the case of jumps in the hazard rate or different intensity function at failures of a large number of copies of a repairable system, are presented. Selection of a suitable extension of the PHM for given data on the basis of residual plots is also discussed. Finally applications of the PHM and its extensions are illustrated with a suitable example. Only the semi-parametric method has been considered. The assumptions made in the PHM for the analysis of repairable systems have been explained graphically as far as possible. Perfect, minimal or imperfect repairs carried out on repairable systems can be taken into consideration for the reliability analysis using the PHM.     

主余震序列作用下结构增量损伤比研究

强震过后短时间内发生的余震会对主震损伤结构产生重要影响,目前针对地下结构抗震性能的研究多是基于单次主震作用,对余震作用的认识有待进一步提高。为研究主余震作用下地下结构的性能劣化及增量损伤,以2层3跨地铁车站为原型建立土–地下结构相互作用模型,选取14次真实地震中的85组天然主震记录和对应的主余震序列为输入,对比研究了地下结构的地震响应特征。结果表明：考虑主余震作用时地下结构的地震损伤程度一般要比仅考虑主震作用时严重,但其增量幅度及扩展范围与主余震序列峰值加速度比ξ、地震动特性和主余震“极性”等因素有关;由于地下结构的损伤累计效应,在相近主余震峰值强度作用下(ξ≈1.0),地铁车站在余震时的层间位移反应较主震更大;当主震与余震的峰值加速度相差较大时(ξ≥1.4),余震对结构造成的附加损伤十分有限。

     

基础隔震结构基于新抗震规范地震动随机模型的地震作用取值

对多自由度基础隔震结构的地震作用取值问题进行了系统研究。首先建立了结构运动方程，接着用实模态对上部结构进行解耦，针对所得运动方程为非对称质量与非经典阻尼矩阵的情况，再用复模态法解耦，最后采用基于新抗震规范的地震动随机模型，运用复模态时域法获得了体系的相对位移，由此便可以得到结构的地震作用取值。最后，通过一个例子来说明多层基础隔震结构的地震作用计算方法，同时给出了由规范的振型分解反应谱法得到的基础固定结构的地震作用取值。     

设计地震波的小波包多尺度调整

提出了一种基于小波包对地震动在不同尺度上进行调整的方法。和传统的小波分析相比，该方法不仅对地震波低频分量进行精确调整，还可对其高频成分实现类似的调整。本文提出的方法可方便地应用于时频联合分析和结构抗震设计中。     

A full history proportional hazards model for preventive maintenance scheduling

This paper is concerned with the development of a realistic preventive maintenance (PM) scheduling model. A heuristic approach for implementing the semi-parametric proportional-hazards model (PHM) to schedule the next preventive maintenance interval on the basis of the equipment's full condition history is introduced. This heuristic can be used with repairable systems and does not require the unrealistic assumption of renewal during repair, or even during PM. Two PHMs are fitted, for the life of equipment following corrective work and the life of equipment following PM, using appropriate explanatory variables. These models are then used within a simulation framework to schedule the next preventive maintenance interval. Optimal PM schedules are estimated using two different criteria, namely maximizing availability over a single PM interval and over a fixed horizon. History data from a set of four pumps operating in a continuous process industry is also used to demonstrate the proposed approach. The results indicate a higher availability for the recommended schedule than the availability resulting from applying the optimal PM intervals as suggested by using the conventional stationary models. © 1997 John Wiley & Sons, Ltd.     

Condition based maintenance optimization for multi-component systems using proportional hazards model

The objective of condition based maintenance (CBM) is typically to determine an optimal maintenance policy to minimize the overall maintenance cost based on condition monitoring information. The existing work reported in the literature only focuses on determining the optimal CBM policy for a single unit. In this paper, we investigate CBM of multi-component systems, where economic dependency exists among different components subject to condition monitoring. The fixed preventive replacement cost, such as sending a maintenance team to the site, is incurred once a preventive replacement is performed on one component. As a result, it would be more economical to preventively replace multiple components at the same time. In this work, we propose a multi-component system CBM policy based on proportional hazards model (PHM). The cost evaluation of such a CBM policy becomes much more complex when we extend the PHM based CBM policy from a single unit to a multi-component system. A numerical algorithm is developed in this paper for the exact cost evaluation of the PHM based multi-component CBM policy. Examples using real-world condition monitoring data are provided to demonstrate the proposed methods.