Post-earthquake economic resilience and recovery efficiency in the border areas of the Tibetan Plateau: A case study of areas affected by the Wenchuan Ms 8.0 Earthquake in Sichuan,China in 2008     

Zhou  Kan  Liu  Baoyin  Fan  Jie 《地理学报(英文版)》2020,30(8):1363-1381

Journal of Geographical Sciences - The border areas of the Tibetan Plateau and the neighboring mountainous areas have a high incidence of earthquakes with a magnitude greater than Ms 5.0, as well...  相似文献   

一种基于自证明公钥的可公开验证的认证加密方案     

彭银桥  甘元驹  邓锐  彭凌西  陈月峰 《广东海洋大学学报》2005,25(3):73-75

针对现有的基于证书的认证加密方案通信量和计算量大的缺点,提出了基于自证明公钥的可公开验证的认证加密方案。详细阐述了方案的系统初始化、签名生成、消息恢复验证以及公开验证4个阶段,方案的安全性是基于求解离散对数的困难性(DLP)和强单向hash函数(OWFH)的不可逆。该方案在没有签名者的协作下,任何验证者都可验证签名者的诚实性,在验证签名的同时可认证签名者的公钥,因而减少了存储空间、通信量和计算量。  相似文献   

Numerical estimation of REV and permeability tensor for fractured rock masses by composite element method   总被引：2，自引：0，他引：2  

S.‐H. Chen  X.‐M. Feng  S. Isam 《国际地质力学数值与分析法杂志》2008,32(12):1459-1477

The Monte Carlo method is used to generate parent stochastic discrete fracture network, from which a series of fractured rock samples of different sizes and orientations are extracted. The fracture network combined with a regular grid forms composite element mesh of the fractured rock sample, in which each composite element is composed of sub‐elements incised by fracture segments. The composite element method (CEM) for the seepage is implemented to obtain the nodal hydraulic potential as well as the seepage flow rates through the fractured rock samples. The application of CEM enables a large quantity of stochastic tests for the fractured rock samples because the pre‐process is facilitated greatly. By changing the sizes and orientations of the samples, the analysis of the seepage characteristics is realized to evaluate the variation of the permeability components, the existence of the permeability tensor and the representative element volume. The feasibility and effectiveness are illustrated in a numerical example. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Dynamic properties of green water event in the overtopping of extreme waves on a fixed dock     

Nobuhito Mori  Daniel T. Cox 《Ocean Engineering》2003,30(16):2021-2052

A statistical model is developed to predict wave overtopping volume and rate of extreme waves on a fixed deck. The probability density function for the volume and rate of overtopping water are formulated based on the truncated Weibull distribution with the assumption of local sinusoidal profile for small amplitude waves. Sensitivity to the wave nonlinearity parameter and deck clearance is discussed. The statistical model is compared to laboratory data of the instantaneous free surface elevation measured in front of a fixed deck, and overtopping volume and overtopping rate measured at the leading edge of the deck. The statistical theory compared well with the measured exceedance probability seaward of the deck. The model prediction of the exceedance probability of deck overtopping gave qualitatively good agreement for large overtopping values.  相似文献   

钛型吸附剂的表面特性     

谢式南  王俊鹤  周英兰  孙爱平 《中国海洋大学学报(自然科学版)》1990,(3)

用自装的BET容量法装置测定了几种粒状钛型吸附剂的比表面及其孔径分布。测定是在常温减压下进行的。结果表明:钛型吸附剂在加铀海水中的吸铀量与样品的比表面及孔径分布有一定的内在联系。这种表面性质的研究对吸附剂的筛选有重要的指导意义。  相似文献   

Virgin rock temperatures from well logs — accuracy analysis for some advanced inversion models     

C. Hermanrud  P.Y. Shen 《Marine and Petroleum Geology》1989,6(4)

Temperature data from 18 measurement series obtained during logging of the Oseberg field in the northern North Sea are presented. Because the measurement series are taken at approximately the same depth, they should give identical temperatures after depth correction, and are suitable for assessing the performance of different models used to determine virgin rock temperatures from well log information.We have used this data set to test the properties of the different models given by Shen and Beck (1986). Although these models were built to simulate closely the thermal recovery of a well and are unbiased, the uncertainties in the temperature estimates when applied to real data are found to be no less than those from simpler (biased) models. This fact confirms the conclusion of Hermanrud (1989a) who showed that physical factors other than those presently accounted for significantly influence the thermal recovery of a borehole.  相似文献   

A community-wide intercomparison exercise for the determination of dissolved iron in seawater     

Andrew R. Bowie  Eric P. Achterberg  Peter L. Croot  Hein J.W. de Baar  Patrick Laan  James W. Moffett  Simon Ussher  Paul J. Worsfold 《Marine Chemistry》2006

The first large-scale international intercomparison of analytical methods for the determination of dissolved iron in seawater was carried out between October 2000 and December 2002. The exercise was conducted as a rigorously “blind” comparison of 7 analytical techniques by 24 international laboratories. The comparison was based on a large volume (700 L), filtered surface seawater sample collected from the South Atlantic Ocean (the “IRONAGES” sample), which was acidified, mixed and bottled at sea. Two 1-L sample bottles were sent to each participant. Integrity and blindness were achieved by having the experiment designed and carried out by a small team, and overseen by an independent data manager. Storage, homogeneity and time-series stability experiments conducted over 2.5 years showed that inter-bottle variability of the IRONAGES sample was good (< 7%), although there was a decrease in iron concentration in the bottles over time (0.8–0.5 nM) before a stable value was observed. This raises questions over the suitability of sample acidification and storage.  相似文献   

Variation in Water Masses on Shelf of Northern Bering Sea in September 2016-2018     

Yingjie Wang  Na Liu  Lina Lin  Yan He  Bin Kong  Zhanhai Zhang 《Marine Geodesy》2020,43(3):285-301

Abstract

Based on hydrological data obtained during the 7th to 9th Chinese National Arctic Research Expeditions in the summers of 2016–2018, the main water structure on the shelf of the northern Bering Sea and the volume and heat fluxes of the Bering Strait throughflow were analyzed. Distinct variability was identified in the three Pacific water masses feeding the strait - Anadyr Water (AW), Bering Shelf Water (BSW) and Alaskan coastal water (ACW). Overall, the temperature and salinity of the entire section increased each year, with 2018 showing significant anomalies, i.e., a temperature anomaly of up to 1?°C and a maximum salinity anomaly of 2. From 2016 to 2018, the extent of the ACW gradually narrowed in the eastern part of this section, while the AW expanded eastward each year. The net volume transport through each of the three sections increased poleward from 1.65?Sv to 2.76?Sv, with the AW increasing from 0?Sv to 1.03?Sv, the BSW varying between 0.52–1.65?Sv, and the ACW gradually decreasing from 1.04?Sv to disappearing completely. The net heat fluxes were also poleward, varying between 25.77 TW and 61.50 TW, and showing a significant increase. Significant variations in magnitude and extent were observed in each water mass of the Bering Strait throughflow, which could produce widespread effects in the Arctic Ocean and the global ocean beyond.  相似文献   

Community turnover provides insight into variable invertebrate recovery between restored streams with different integrated catchment management plans     

Sharon Elizabeth Graham  John Martin Quinn 《新西兰海洋与淡水研究杂志》2020,54(3):467-489

ABSTRACT

Understanding temporal patterns in restored environments is important for identifying potential barriers to recovery and improved management of degraded habitats. In this paper, we use temporal beta diversity analyses to compare invertebrate community recovery trajectories in three restored agricultural stream sites under different integrated catchment plans, a native forest reference site, and two unmodified pasture control stream sites over 24 years. The restored sites diverged from their initial community composition over time and became more similar to the reference site community, which was relatively stable over time. Variation partitioning showed that prior to restoration beta diversity was primarily associated with environmental and spatial drivers, whereas post-restoration beta diversity was more influenced by temporal and environmental drivers, including changes in substrate size, fine sediments, water clarity, and nutrients, as well as temperature and flow regime. Species’ contributions to beta diversity varied between sites and years, with sensitive EPT taxa contributing more in reference and control sites. However, contributions of some EPT species, particularly mayflies, increased in restored sites post-ICM. In summary, after nearly two decades of ICM, restored stream sites show recovery towards reference conditions, yet differences persist, indicating that rehabilitation may take longer, depending on the restoration goals.  相似文献   

Fish-farming effects on benthic community structure in coastal sediments: analysis of meiofaunal recovery   总被引：8，自引：0，他引：8  

Mazzola  A.; Mirto  S.; La Rosa  T.; Fabiano  M.; Danovaro  R. 《ICES Journal of Marine Science》2000,57(5):1454-1461

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