中国南海极端风暴海况下固定式平台结构可靠性分析

基于中国南海海域风暴环境条件,研究分析南海海域固定式导管架平台结构整体性和可靠性,以及新建固定式平台结构设计准则。采用海洋环境数据后报方法,得到南海海域1972~2011共40年的风、浪、流联合数据,从中抽取风暴环境条件;利用通用荷载模型,将40年间的风暴环境数据转变成结构的荷载数据,即基底剪力或倾覆力矩;并计算得到风暴环境荷载的短期及长期分布,以及任意风暴下荷载的概率分布;根据结构可靠性模型,结合荷载的长期分布,研究基于结构暴露等级及失效概率的固定式平台结构强度储备比。根据计算,得到了不同暴露等级下中国南海平台的强度储备比,并与墨西哥湾及北海海域进行了比较,为新建平台提供设计参考。     

基于可靠性的海洋石油平台维修策略研究

针对海洋石油平台传统维修方式依赖经验的缺陷,从可靠性分析角度来制定维修策略,包括确定最佳维修周期和制定设备的检修顺序。以胜利油田埕岛中心一号海洋石油动力平台电力系统为例,采用基于最小割集的数值仿真方法进行故障树分析,通过任务可靠度推出任务时间,实现以可靠性为中心的最佳预防性维修周期的确定。此外,对系统进行重要度分析,按关键重要度大小进行排序,从而制定设备的检修顺序。     

考虑优势流作用的降雨入渗边坡可靠度分析

降雨诱发滑坡是世界上最普遍的地质灾害,而关于降雨入渗对边坡的可靠度分析,优势入渗的影响被长期忽视。使用Comsol Multiphysics对降雨条件下优势入渗做数值求解,利用无限边坡模型计算边坡安全系数;并应用改进Cholesky分解法生成空间相关随机场,使用蒙特卡洛方法分析降雨过程中边坡的可靠度。结合确定性与可靠度计算对比均质入渗与优势入渗在降雨过程中边坡安全性变化：（1）降雨强度较低时,优势入渗安全性较好,而降雨强度较高时,均质入渗更稳定;（2）均质入渗中参数空间变异性是边坡失稳破坏的关键因素,而优势入渗的边坡失稳则由湿润峰快速推进所导致;（3）针对优势入渗模型研究,发现基质域与优势域水力交换强度较大时边坡有更大概率失稳,而较小的水力交换强度可能影响边坡底部的失稳破坏。     

省级气象宽带网可靠性设计

气象业务的发展和社会需求的增长,对广域宽带网络系统提出更高要求,不但要求传输的数据量大,时效性强,而且要求其可靠性高。目前各省级气象局的宽带网可靠性设计,大都采用降级备份,无法做到双链路自动切换、无缝备份,难以满足气象业务7×24 h从不间断的实际需求,网络可靠性有待进一步提高。该文提出一种基于双向转发检测 (BFD) 和策略路由技术的网络可靠性设计方案,应用该方案不仅使网络结构和带宽有大幅提升,还能实现业务分流、链路冗余和故障自动切换,提高气象宽带网的可靠性水平。该方案经严格测试后,已依托广东省气象宽带网得以实现并投入业务运行,效果良好。同时,该设计对其他省级气象网络建设有一定参考价值。     

西北地区五城市大型水源地地下水流模型若干问题研究

西北地区五城市系指西安市、兰州市、乌鲁木齐市、西宁市与银川市。五城市在“七五”期间分别建立了大型水源地的地下水管理模型，而地下水流模型的建立则是制作地下水管理模型的基础。一个好的地下水流模型对概化的水文地质模型必须有高度的仿真性，通过拟合求参必须有足够的保真性，对于预测必须有可靠性。     

土层随机地震反应的动力可靠度计算

研究了土层的随机地震反应分析方法 ,建立了基岩输入地震动加速度功率谱函数为白噪声和过滤白噪声时土层的动力可靠度计算理论     

星载铷原子频率标准的可靠性研究

星载原子频率标准在许多空间系统中担当着重要的角色,其性能和可靠性对这些系统的功能有重要的影响。介绍了广泛使用的星载铷原子频率标准的基本工作原理,分析了影响其可靠性的各种因素,并探讨了提高其可靠性的基本途径。     

A reliability‐based selective index for regional flood frequency analysis methods

In this paper, a new index is proposed for the selection of the best regional frequency analysis method. First, based on the theory of reliability, the new selective index is developed. The variances of three regional T‐year event estimators are then derived. The proposed methodology is applied to an actual watershed. For each regional method, the reliability of various T‐year regional estimates is computed. Finally, the reliability‐based selective index graph is constructed from which the best regional method can be determined. In addition, the selection result is compared with that based on the traditional index, root mean square error. The proposed new index is recommended as an alternative to the existing indices such as root mean square error, because the influence of uncertainty and the accuracy of estimates are considered. Copyright © 2003 John Wiley & Sons, Ltd.     

Probabilistic seismic response and reliability assessment of isolated bridges

Bridge seismic isolation strategy is based on the reduction of shear forces transmitted from the superstructure to the piers by two means: shifting natural period and earthquake input energy reduction by dissipation concentrated in protection devices. In this paper, a stochastic analysis of a simple isolated bridge model for different bridge and device parameters is conducted to assess the efficiency of this seismic protection strategy. To achieve this aim, a simple nonlinear softening constitutive law is adopted to model a wide range of isolation devices, characterized by only three essential mechanical parameters. As a consequence of the random nature of seismic motion, a probabilistic analysis is carried out and the time modulated Kanai-Tajimi stochastic process is adopted to represent the seismic action. The response covariance in the state space is obtained by solving the Lyapunov equation for a stochastic linearized system. After a sensitivity analysis, the failure probability referred to extreme displacement and the mean value of dissipated energy are assessed by using the introduced stochastic indices of seismic bridge protection efficiency. A parametric analysis for protective devices with different mechanical parameters is developed for a proper selection of parameters of isolation devices under different situations.     

Reliability checking for GNSS baseline and network processing

Reliability analysis is inseparably connected with the formulation of failure scenarios, and common test statistics are based on specific assumptions. This is easily overlooked when processing observation differences. Poor failure identification performance and misleading pre-analysis results, mainly meaningless minimum detectable biases and external reliability measures, are the consequence. A reasonable failure scenario for use with differenced GNSS observations is formulated which takes into account that individual outliers in the original data affect more than one processed observation. The proper test statistics and reliability indicators are given for use with correlated observations and both batch processing and Kalman filtering. It is also shown that standardized residuals and redundancy numbers fail completely when used with double differenced observations.