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81.
Recently,the expertise accumulated in the field of geovisualization has found application in the visualization of abstract multidimensional data,on the basis of methods called spatialization methods.Spatialization methods aim at visualizing multidimensional data into low-dimensional representational spaces by making use of spatial metaphors and applying dimension reduction techniques.Spatial metaphors are able to provide a metaphoric framework for the visualization of information at different levels of gran... 相似文献
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Athanassios Ganas Zafeiria Roumelioti Vassilios Karastathis Konstantinos Chousianitis Alexandra Moshou Evangelos Mouzakiotis 《Journal of Seismology》2014,18(3):433-455
We investigate mainshock slip distribution and aftershock activity of the 8 January 2013 M w?=?5.7 Lemnos earthquake, north Aegean Sea. We analyse the seismic waveforms to better understand the spatio-temporal characteristics of earthquake rupture within the seismogenic layer of the crust. Peak slip values range from 50 to 64 cm and mean slip values range from 10 to 12 cm. The slip patches of the event extend over an area of dimensions 16?×?16 km2. We also relocate aftershock catalog locations to image seismic fault dimensions and test earthquake transfer models. The relocated events allowed us to identify the active faults in this area of the north Aegean Sea by locating two, NE–SW linear patterns of aftershocks. The aftershock distribution of the mainshock event clearly reveals a NE–SW striking fault about 40 km offshore Lemnos Island that extends from 2 km up to a depth of 14 km. After the mainshock most of the seismic activity migrated to the east and to the north of the hypocenter due to (a) rupture directivity towards the NE and (b) Coulomb stress transfer. A stress inversion analysis based on 14 focal mechanisms of aftershocks showed that the maximum horizontal stress is compressional at N84°E. The static stress transfer analysis for all post-1943 major events in the North Aegean shows no evidence for triggering of the 2013 event. We suggest that the 2013 event occurred due to tectonic loading of the North Aegean crust. 相似文献
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Romeu Silva Vicente Hugo Rodrigues Humberto Varum Aníbal Costa Jos António Raimundo Mendes da Silva 《地震工程与工程振动(英文版)》2012,11(1):23-34
This paper discusses the issue of performance requirements and construction criteria for masonry enclosure and infill walls.Vertical building enclosures in European countries are very often constituted by non-load-bearing masonry walls, using horizontally perforated clay bricks.These walls are generally supported and confined by a reinforced concrete frame structure of columns and beams/slabs.Since these walls are commonly considered to be nonstructural elements and their influence on the structural response is ignored,their consideration in the design of structures as well as their connection to the adjacent structural elements is frequently negligent or insufficiently detailed.As a consequence,nonstructural elements,as for wall enclosures,are relatively sensitive to drift and acceleration demands when buildings are subjected to seismic actions. Many international standards and technical documents stress the need for design acceptability criteria for nonstructural elements,however they do not specifically indicate how to prevent collapse and severe cracking,and how to enhance the overall stability in the case of moderate to high seismic loading.Furthermore,a review of appropriate measures to improve enclosure wall performance and both in-plane and out-of-plane integrity under seismic actions is addressed. 相似文献
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Sofia U. Holmgren Christian Bigler Ólafur Ingólfsson Alexander P. Wolfe 《Journal of Paleolimnology》2010,43(2):393-412
Lake sediments from four small lakes on western Spitsbergen (Svalbard Archipelago, Norwegian High Arctic) preserve biostratigraphic and isotopic evidence for a complex suite of twentieth century environmental changes. At Lake Skardtjørna and Lake Tjørnskardet on Nordenskiöldkysten, there is a marked diatom floristic change coupled to increased diatom concentrations beginning around 1920. At Lake Istjørna and Lake Istjørnelva, 25 km southwest of Longyearbyen, both diatom total valve and chrysophyte stomatocyst concentrations have increased dramatically since the beginning of the 1900s. The early twentieth century changes are probably related to climate warming after the Little Ice Age. However, the most pronounced changes in diatom assemblages seem to have occurred in the last few decades. At the same time, nitrogen stable isotopes in sediment organic matter in two of the lakes became progressively depleted by ~2‰, which is consistent with diffuse atmospheric inputs from anthropogenic sources and attendant fertilization. These data suggest that climate change and nitrogen deposition may be acting together in driving these lakes towards new ecological states that are unique in the context of the Holocene. 相似文献
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Maria F. Gazulla Maria P. Gómez Mónica Orduña Eulalia Zumaquero Sonia Vicente 《Geostandards and Geoanalytical Research》2009,33(1):71-84
A study has been undertaken to determine sulfur in geological samples by coupled analytical techniques. Two measurement methods have been developed: one using an electric furnace coupled to an ion chromatograph (electric furnace-IC) and another using infrared (IR) and quadrupole mass spectrometry (QMS) for evolved gas analysis (EGA) coupled with a thermogravimetric analyser (TGA). In the electric furnace-IC method, measurement was performed without any sample pre-treatment. The measurement conditions were optimised by varying sample quantity, type of catalyst (WO3 , Cu, W and V2 O5 ) and sample/catalyst ratio, and the detection limit was 10 μg g−1 . Sulfur ores decompose at different temperatures. However, TGA-EGA allowed identification of the different forms of sulfur in the sample, even when they were found in very low concentrations, because the sulfur was continuously analysed. The developed chromatographic method allowed simultaneous analysis of several sample components, such as S, Cl and F, with a low detection limit. The method was much faster and more specific than the methods described in the literature. The results of the sulfur determination had low scatter, possibly because the samples underwent little handling during analysis: the operator only weighed and placed the sample in the furnace, the rest of the measurement process was fully automated. The results obtained by both the developed methods have been validated by using reference materials and comparison with combustion-IR spectroscopy, a standard method for determining total sulfur in a sample. 相似文献