埋地管道震害的多因素灰色关联分析

根据多次历史地震埋地管道震害调查资料的统计和定性分析，应用灰色系统理论，以管道震害率作为参考数列，以地震烈度、场地类型、管道材料、接口构造和管径尺寸作为比较数列，对埋地管道震害率进行了多因素灰色关联分析，排出了关联序．研究结果客观地揭示出震害率与各影响因素之间的相互关系，为进一步研究理地管道的震害预测方法提供了科学依据．     

基于层次-模糊评价法的山区油气管道地质灾害易发性研究

针对山区油气管道地质灾害的基本特征,将层次分析与模糊综合评价相结合,建立起可用于山区管道地质灾害易发性评价的层次-模糊评价模型;并从自然因素、管道敷设状况、灾害活动和设计与误操作四个方面建立山区油气管道地质灾害易发性评价体系.首先依据专家经验构造各层影响因素的判断矩阵,并利用层次分析法求出各影响因素的权重集,然后对山区油气管道地质灾害易发性进行多级模糊综合评价,最终根据评价结果确定山区油气管道地质灾害易发性等级.通过具体实例检验了本文所建立评价方法的应用效果.     

Tapping the leakages: Methane losses, mitigation options and policy issues for Russian long distance gas transmission pipelines

The Russian natural gas industry is the world's largest producer and transporter of natural gas. This paper aims to characterize the methane emissions from Russian natural gas transmission operations, to explain projects to reduce these emissions, and to characterize the role of emissions reduction within the context of current GHG policy. It draws on the most recent independent measurements at all parts of the Russian long distance transport system made by the Wuppertal Institute in 2003 and combines these results with the findings from the US Natural Gas STAR Program on GHG mitigation options and economics.With this background the paper concludes that the methane emissions from the Russian natural gas long distance network are approximately 0.6% of the natural gas delivered. Mitigating these emissions can create new revenue streams for the operator in the form of reduced costs, increased gas throughput and sales, and earned carbon credits. Specific emissions sources that have cost-effective mitigation solutions are also opportunities for outside investment for the Joint Implementation Kyoto Protocol flexibility mechanism or other carbon markets.     

压力管道泄漏声发射源定位的实验研究

结合实验室声发射仪和油气管道设备,建立了充气管道泄漏声发射检测系统模型,分别在传感器间距、管道压力和泄漏量三种变化状态下进行了泄漏源定位影响实验。对管道泄漏声发射信号的时域统计特征、频域分布特征以及泄漏信号的相关性作了分析;从声信号能量累计和衰减特性方面对互相关定位法和幅度衰减测量区域定位法的可行性进行了计算,表明在传感器间距较小和泄漏量较小的状态下,在背景噪声较小的环境中,用互相关法具有较好的定位精度;而幅度衰减测量区域定位方法对泄漏源的定位误差较大。     

Homology and phylogeny and their automated inference

The analysis of the ever-increasing amount of biological and biomedical data can be pushed forward by comparing the data within and among species. For example, an integrative analysis of data from the genome sequencing projects for various species traces the evolution of the genomes and identifies conserved and innovative parts. Here, I review the foundations and advantages of this "historical" approach and evaluate recent attempts at automating such analyses. Biological data is comparable if a common origin exists (homology), as is the case for members of a gene family originating via duplication of an ancestral gene. If the family has relatives in other species, we can assume that the ancestral gene was present in the ancestral species from which all the other species evolved. In particular, describing the relationships among the duplicated biological sequences found in the various species is often possible by a phylogeny, which is more informative than homology statements. Detecting and elaborating on common origins may answer how certain biological sequences developed, and predict what sequences are in a particular species and what their function is. Such knowledge transfer from sequences in one species to the homologous sequences of the other is based on the principle of 'my closest relative looks and behaves like I do', often referred to as 'guilt by association'. To enable knowledge transfer on a large scale, several automated 'phylogenomics pipelines' have been developed in recent years, and seven of these will be described and compared. Overall, the examples in this review demonstrate that homology and phylogeny analyses, done on a large (and automated) scale, can give insights into function in biology and biomedicine.     

污水管道增强通风作用下氧气气液传质特性

污水管道的厌氧环境是诱发H2S和CH4等有毒有害气体产生的主要原因,结合我国污水收集系统内建筑排水立管与市政污水管道之间设置化粪池加剧了污水管道通风不畅的现状,提出将建筑排水立管与污水管道直连形成的增强通风系统能够有效提高污水管道通风量,来改善管道气相空间环境.在此基础上,结合实验和计算流体动力学(CFD)仿真方法,以...     

IAFSA-GRNN在油田集输管道CO2腐蚀速率预测中的应用

为提高油田集输管道CO₂腐蚀速率预测的准确性,针对原始广义回归神经网络(GRNN)预测精度低的问题,提出改进的群智能算法优化原始GRNN的预测模型;分别使用GRNN模型、人工鱼群算法(AFSA)优化的GRNN(AFSA-GRNN)模型和自适应改进的AFSA-GRNN(IAFSA-GRNN)模型预测X65管线钢的CO₂腐蚀速率。结果表明:采用AFSA和IAFSA优化光滑因子S后,能大大提高GRNN模型的预测精度,预测结果的平均相对误差由36.09%分别减小至7.20%和6.90%;与AFSA相比,IAFSA优化的GRNN不仅具有更高的预测精度,还具有更快的收敛速度。AFSA-GRNN在第164次迭代计算时收敛,而IAFSA-GRNN在第109次迭代计算时收敛,说明AFSA经自适应优化能提高优化过程的收敛速度和GRNN的预测精度。