A novel tool for Bayesian reliability analysis using AHP as a framework for prior elicitation

Quantitative risk assessment (QRA) is a powerful and popular technique to support risk-based decisions. Unfortunately, QRAs are often hampered by significant uncertainty in the frequency of failure estimation for physical assets. This uncertainty is largely due to lack of quality failure data in published sources. The failure data may be limited, incompatible and/or outdated. Consequently, there is a need for robust methods and tools that can incorporate all available information to facilitate reliability analysis of critical assets such as pipelines, pressure vessels, rotating equipment, etc. This paper presents a novel practical approach that can be used to help overcome data scarcity issues in reliability analysis. A Bayesian framework is implemented to cohesively integrate objective data with expert opinion with the aim toward deriving time to failure distributions for physical assets. The Analytic Hierarchy Process is utilized to aggregate time to failure estimates from multiple experts to minimize biases and address inconsistencies in their estimates. These estimates are summarized in the form of informative priors that are implemented in a Bayesian update procedure for the Weibull distribution. The flexibility of the proposed methodology allows for efficiently dealing with data limitations. Application of the proposed approach is illustrated using a case study.     

Model-based information fusion investigation on fault isolation of subsea systems considering the interaction among subsystems and sensors

The offshore oil industry has expanded to deep water and Arctic. The harsh operating conditions (e.g., ice and strong wind) and increasing complicated system raise the occurrence likelihood of system faults. This requires timely fault isolation and management in the subsea system. However, the offshore oil industry mainly relies on humans to isolate faults based on alarms. With harsh operating conditions and increasing complicated system, this industry urgently needs research on more efficient fault isolation and cause diagnosis methods. Unfortunately, limited research is conducted on fault isolation method in the offshore oil industry. Furthermore, in industry 4.0 era, large amounts of information are obtained. This provides precondition for the application of information fusion technique which aims to improve diagnosis results. However, to the authors’ knowledge, information fusion has not been much studied in the fault isolation of the offshore oil industry. Moreover, the interaction of different subsystems contains valuable information. How the interaction of different subsystems can influence the fault diagnosis has not been explored. This paper proposes a Bayesian network (BN) based method for timely fault isolation and cause diagnosis for the offshore oil industry. The work fuses different information, and it also includes the dependency among different subsystems in the fault diagnosis. As an important alarm source, false alarms are also taken into account in the model. A case study on the subject of the subsea wellhead and chemical injection systems is conducted to demonstrate the functions and merits of the proposed method.     

Analysis of Extreme Summer Rainfall Using Climate Teleconnections and Typhoon Characteristics in South Korea1

Abstract: It is now widely acknowledged that climate variability modulates the frequency of extreme hydrological events. Traditional methodologies for hydrologic frequency analysis are not devised to account for variation in the exogenous teleconnections. Flood frequency analysis is further plagued by the assumptions of stationary in the causal structure as well as ergodicity. Here, we propose a dynamical hierarchical Bayesian analysis to account for exogenous forcing that govern the summer season rainfall. The precursors for Korean summer rainfall at different frequencies are identified utilizing wavelet and independent component analyses. The sea surface temperatures, the ensemble of rainfall predictions by General Circulation Model, in addition to the typhoon attributes were found to have direct correlation with extreme rainfall events and were used as inputs to the logistic regression model. The model parameters are estimated using Markov Chain Monte Carlo and the resulting posterior distributions associated with individual inputs are analyzed to advance our understanding of the spatiotemporal impact of the teleconnections. Eight rainfall stations throughout Korea are considered in this analysis. We demonstrate that the probability of occurrence of extreme events could be successfully projected at a 90% rate of correct classification of extreme events.     

用vb.net开发电子阅览室机位分配系统

电子阅览室在使用新的一卡通系统后,针对一卡通软件某些方面的不足,采用vb．net开发了机位分配系统。本文对vb与vb．net两种开发工具以及它们的区别和该软件的一些新功能进行了讨论,并列出了程序中的部分源代码。     

Assessing the Effectiveness of a Constructed Arctic Stream Using Multiple Biological Attributes

Objective assessment of habitat compensation is a central yet challenging issue for restoration ecologists. In 1997, a 3.4-km stream channel, designed to divert water around an open pit diamond mine, was excavated in the Barrenlands region of the Canadian Arctic to create productive stream habitat. We evaluated the initial success of this compensation program by comparing multiple biological attributes of the constructed stream during its first three years to those of natural reference streams in the area. The riparian zone of the constructed stream was largely devoid of vegetation throughout the period, in contrast to the densely vegetated zones of reference streams. The constructed stream also contained lower amounts of woody debris, coarse particulate organic matter (CPOM), and epilithon; had lower coverage by macrophytes and bryophytes; and processed leaf litter at a lower rate than reference streams. Species richness and densities of macroinvertebrates were consistently lower in the constructed stream compared to natural streams. This contributed to differences in macroinvertebrate assemblage structure throughout the period, although assemblages showed some convergence by year 3. The effectiveness of the constructed stream to emulate natural streams varied somewhat depending on the biological attribute being evaluated. Assessments based on individual attributes showed that minimal to moderate levels of similarity between the constructed stream and natural streams were achieved. A collective assessment of all biological and ecosystem attributes suggested that the constructed stream was not a good surrogate for natural streams during these first years. Additional time would be required before many characteristics of the constructed stream would resemble those of reference streams. Because initial efforts to improve fish habitat in the constructed stream focused on physical structures (e.g., weirs, vanes, rock, groins), ecological factors limiting fish growth were not considered and likely constrained success. We suggest that a greater focus on organic characteristics and vegetation within the stream and its riparian zone could have accelerated compensation. The addition of woody debris and CPOM, combined with planting of shrubs and herbs along the stream, should provide a source of allochthonous matter for the biotic community while large cobble and boulders should improve the physical stability of stream system, protecting its organic components.     

风荷载作用下单层平面索网体系点支式玻璃幕墙的动力性能研究

近年来,单层平面索网体系点支式玻璃幕墙以其简洁、通透的特点在国内外得到广泛的应用,其破坏主要由风荷载造成,目前国内外针对此种结构的风振动力性能研究甚少。本文应用谐波叠加法模拟了脉动风速的时程曲线,进而得到风荷载;通过有限元分析软件ANSYS,对单层平面索网体系点支式玻璃幕墙模型进行动力风荷载下的时程分析,研究在动力风荷载下,幕墙的玻璃面板厚度、拉索截面积以及拉索预拉力对其受力性能的影响,以供幕墙设计参考。     

广西贺州市典型矿区周边耕层土壤Cd通量特征

广西是我国西南部典型的地质高背景区,碳酸盐岩、黑色岩系、基性-超基性岩体与金属矿床（矿化体）强烈的风化成壤作用,使土壤重金属镉（Cd）含量高于全国其他地区.为了查明在地质高背景区矿业活动对耕层土壤环境质量的影响程度,在广西贺州市选取矿业活动影响区和对照区为研究区,系统开展了耕层土壤Cd输送途径及输送通量密度的对比研究.结果表明,在矿区和对照区耕层土壤中,Cd大气干湿沉降通量密度平均值分别为1.87 g·（hm²·a）^-1和1.52 g·（hm²·a）^-1,分别占总输入通量密度的61.5%和60.3%,施肥和灌溉输入土壤Cd通量密度较低;Cd的输出途径均以地表水下渗为主,分别占总输出通量密度的75.4%和86.6%,农作物收割输出通量密度矿区高于对照区,且矿区内种植的水稻籽实Cd含量超标率更高,玉米籽实则未超标.整体上,矿区与对照区土壤Cd净输送通量密度分别为-3.05 g·（hm²·a）^-1和-4.05 g·（hm²·a）^-1,表现为土壤Cd淋失状态,但大气干湿沉降输入通量密度高值点和水稻籽实Cd含量超标点均主要分布在矿区周围,有可能对当地居民健康造成潜在威胁,因此建议通过监控和种植结构调整对该区域Cd污染土壤进行治理.     

融合多源时空数据的地下水硫酸盐预测模型

准确预测地下水SO₄ ^2-空间变化趋势对改善地下水质量、提高区域地下水管理水平具有重要意义.以2011、2014、2017和2020年叶尔羌河流域平原区土地覆盖数据、土壤参数数据、数字高程数据等多源时空数据和地下水pH值为特征变量,分析其与地下水SO₄ ^2-浓度的相关性,利用贝叶斯优化算法优化随机森林回归,建立BOA-RFR模型,并基于BOA-RFR模型对特征变量进行重要性分析,对模型预测精度进行评价,最后生成地下水SO₄ ^2-预测图.结果表明,pH值、地面高程（GE）和贡献区荒地（BAR）面积占比作为影响地下水水化学组分的重要参数,与地下水SO₄ ^2-浓度均呈现极显著负相关,对地下水SO₄ ^2-浓度预测的重要度均大于25 %;地统计插值方法作为空间分布预测建模的辅助手段,加入辅助样本后的BOA-RFR模型,地下水SO₄ ^2-浓度预测的R²均大于0.96,且多辅助样本构建模型的RMSE和MAE最大值较少样本模型的最小值分别降低了4.7 %和23.8 %;在地下水SO₄ ^2-浓度预测中,高SO₄ ^2-地下水向叶尔羌河流域平原区东北部富集,且面积呈扩张趋势.     

单层平面索网玻璃幕墙结构研究现状综述

单层平面索网玻璃幕墙是点支式玻璃幕墙的一种重要型式,其幕墙玻璃的支承结构为单层平面索网结构,在国内外一些大型公共建筑中得到了广泛的应用。综述了单层平面索网结构的研究现状,重点阐述了其几何非线性特征、玻-索协同工作特性,以及该类结构的动力特性及动力响应等研究成果。同时,对单层平面索网玻璃幕墙结构研究中所存在的问题进行了分析,并对其发展趋势作了展望。     

水市场双边叫价贝叶斯博弈模型及机制设计研究

通过水权交易提高水资源的使用效率和配置效率,实现水资源最优配置。水权和水市场理论研究是水资源可持续利用的重要研究课题,而水权交易模型是水市场理论与实践中水权交易的核心。针对水权交易市场最常见的双边交易,采用双边拍卖的交易模式,通过对水权交易市场的双边交易进行描述分析,建立了水权交易买卖双方叫价拍卖的不完全信息博弈模型,给出双方叫价拍卖的机制设计。该机制具有有效性和激励相容性,最后给出算例。