Statistical moment-based structural damage detection method in time domain

A novel structural damage detection method with a new damage index,i.e.,the statistical moment-based damage detection(SMBDD) method in the frequency domain,has been recently proposed.The aim of this study is to extend the SMBDD method in the frequency domain to the time domain for building structures subjected to non-Gaussian and non-stationary excitations.The applicability and effectiveness of the SMBDD method in the time domainis verified both numerically and experimentally.Shear buildings with various damage scenarios are first numerically investigated in the time domain taking into account the effect of measurement noise.The applicability of the proposed method in the time domain to building structures subjected to non-Gaussian and non-stationary excitations is then experimentally investigated through a series of shaking table tests,in which two three-story shear building models with four damage scenarios aretested.The identified damage locations and severities are then compared with the preset values.The comparative results are found to be satisfactory,and the SMBDD method is shown to be feasible and effective for building structures subjected to non-Gaussian and non-stationary excitations.     

大地震多发于俯冲带和洋底断裂带的交叠区

全世界的大地震都发生在俯冲带,因为在俯冲带中,一个构造板块在另一个之下滑动.但是,俯冲区的哪些地方最有可能发生大地震呢?澳大利亚悉尼大学的科学家研究发现,海底断裂带与俯冲带的交叠区域发生大地震的风险高于其他区域.该项研究成果于2012年12月发表在欧洲地球科学联合会(EGU)的开放获取期刊Solid Earth上.     

新技术节省污水支管修复费用——150万美元

本文简要介绍了CIPP管线修复技术在污水支管中的应用情况,重点介绍了CIPP应用特点。     

The IUGS/IAGC Task Group on Global Geochemical Baselines

The Task Group on Global Geochemical Baselines,operating under the auspices of both the International Union of Geological Sciences(IUGS) and the International Association of Geochemistry(IAGC),has the long-term goal of establishing a global geochemical database to document the concentration and distribution of chemical elements in the Earth's surface or near-surface environment.The database and accompanying element distribution maps represent a geochemical baseline against which future human-induced or natural changes to the chemistry of the land surface may be recognized and quantified.In order to accomplish this long-term goal,the activities of the Task Group include:(1) developing partnerships with countries conducting broad-scale geochemical mapping studies;(2) providing consultation and training in the form of workshops and short courses;(3) organizing periodic international symposia to foster communication among the geochemical mapping community;(4) developing criteria for certifying those projects whose data are acceptable in a global geochemical database;(5) acting as a repository for data collected by those projects meeting the criteria for standardization;(6) preparing complete metadata for the certified projects;and(7) preparing,ultimately,a global geochemical database.This paper summarizes the history and accomplishments of the Task Group since its first predecessor project was established in 1988.     

拉萨地块和羌塘地块多个二叠纪基性岩及一个古特提斯海山的初步古地磁结果:对模拟东冈瓦纳晚古生代裂解的暗示

Detachment of the sliver-like Cimmerian terrane from eastern Gondwana in the Early Permian triggered mafic volcanism in many parts of the rift zone. To understand this tectonic episode we have carried out paleomagnetic investigations on mafic volcanic for-mations that were erupted on key terranes that now form part of Tibet. Specifically, we will present data from sections near Lhasa City (central Lhasa block) and Tuotuohe (central Qiangtang Block) as well as near Gyanyima (Paleotethyan sea-mount) that was emplaced onto the floor of Palaeotethys during the Late Permian. Paleomagnetic plots from each location will be used for tectonic calculations. Our new data will be used to evaluate regional scale models con-cerned with how the Cimmerian terranes in southern and SE Asia (from Iran-Tibet-SW China-Myanmar- Thailand-Sumatra) formerly abutted eastern Gond-wana.     

http://www.sciencedirect.com/science/article/pii/S1674987111001046

The role played by Paleoproterozoic cratons in southern South America from the Mesoproterozoic to the Early Cambrian is reconsidered here.This period involved protracted continental amalgamation that led to formation of the supercontinent Rodinia.followed by Neoproterozoic continental break-up,with the consequent opening of Clymene and Iapetus oceans,and finally continental re-assembly as Gondwana through complex oblique collisions in the Late Neoproterozoic to Early Cambrian.The evidence for this is based mainly on a combination of precise U-Pb SHRMP dating and radiogenic isotope data for igneous and metamorphic rocks from a large area extending from the Rio de la Plata craton in the east to the Argentine Precordillera in the west and as far north as Arequipa in Peru.Our interpretation of the paleogeographical and geodynamic evolution invokes a hypothetical Paleoproterozoic block(MARA) embracing basement ultimately older than 1.7 Ga in the Western Sierras Pampeanas(Argentina),the Arequipa block(Peru),the Rio Apa block(Brazil),and probably also the Paraguaia block(Bolivia).     

Evidence for polychlorinated biphenyls dechlorination in the sediments of Sado Estuary, Portugal

Sediment gravity cores and grab samples were collected in the Sado Estuary and in its coastal area. The cores were sliced on board and the percentage of weight loss on ignition was determined in the laboratory, and analysed for polychlorinated biphenyl (PCB) congeners. PCB contents were higher in samples from the North Channel of the estuary, nearby the industrial zone (max. 114 ng g-1 dry weight), while levels in the coastal area were lower than 4.9 ng g-1. The concentrations of the quantified congeners varied irregularly with sediment depth in the estuary, but showed two opposite distribution patterns in cores from the coastal area: the proportions of lower chlorinated congeners increased with depth, while congeners with higher number of chlorines decreased. This suggests a dechlorination of the most chlorinated congeners into less toxic compounds, under reductive conditions of the sediment. Though measurements were done in natural environment it appears that dechlorination was not entirely dependent on chlorine position in the phenyl rings.     

Bather density as a predominant factor for health effects related to recreational bathing: results from the Greek bathers cohort study

Our aim was to examine the health effects on bathers from exposure to recreational seawater on three beaches with different microbiology quality and bather density through a cohort study. An initial questionnaire and a 10 day follow up were used. Univariate and backward logistic regression analyses were used to asses the risk of developing symptoms or diseases among the bathers. In total, 3805 bathers were included in the study and 149 samples were collected from the three beaches. Despite all the beaches being characterized of high quality the levels of bacterial indicators differed among them. Health effects among bathers were not associated with bacterial indicators. A statistically significant increased risk for symptoms related to respiratory illness, gastroenteritis, medical consultation and use of medication was observed among bathers at the higher bather density beaches. Beach bather numbers should always be taken into account when considering a risk assessment approach.     

PCBs in Central Vietnam coastal lagoons: levels and trends in dynamic environments

PCBs were analysed in surficial sediments and selected sediment cores collected between 2002 and 2008 in Central Vietnam coastal lagoons. The aim was to determine contamination levels and trends, and to evaluate the effects of anthropogenic pressures and natural events. Samples were mostly fine-grained with low total PCB concentrations (0.367-44.7 μg kg⁻¹). Atmospheric transport and post depositional processes modify to some degree the fingerprint of PCB inputs to the environment favouring the predominance of 3, 4 and 5 chlorinated congeners. The similarity of congener distributions in contemporary surficial samples also suggests the presence of a unique source over the entire study area, probably connected to mobilisation and long range transports from land-based stocks. The removal of consistent sediment layers is hypothesised based on repeated samplings of the same area. Natural meteorological events (such as typhoons) are suspected to be responsible for these sediment losses.