Dynamic characteristics of a base isolated building from ambient vibration measurements and low level earthquake shaking   总被引：3，自引：0，他引：3  

C. E. Ventura  W. D. Liam Finn  J. -F. Lord  N. Fujita 《Soil Dynamics and Earthquake Engineering》2003,23(4):313-322

Ambient vibration tests were conducted on a base-isolated apartment building in Takamatsu, Japan, to determine the mode shapes and the associated natural frequencies and damping ratios at very low levels of excitation. The latest developments in signal analysis for modal decomposition are used to analyze the ambient response data. A finite element model of the building and isolators was calibrated and refined using the experimental results from the ambient vibration tests. This model was then used to simulate the recorded response of the building under excitation from a small earthquake. The finite element model, calibrated by ambient vibration data and the low level of earthquake shaking, provides the starting point for modelling the non-linear response of the building when subjected to strong shaking.  相似文献   

Quaternary coastline evolution of Lake Ohrid (Macedonia/Albania)     

Nadine Hoffmann  Klaus Reicherter  Christoph Grützner  Jochen Hürtgen  Andreas Rudersdorf  Finn A. Viehberg  Martin Wessels 《Central European Journal of Geosciences》2012,4(1):94-110

Lake Ohrid (between FYR of Macedonia and Albania), situated in an active tectonic region of the Balkanides, is characterized by N ?? S trending active faults. To reconstruct the Holocene shoreline evolution we investigated the coastline using sediment cores and geophysical methods to image sedimentary and tectonic structures. We revealed areas of differing sedimentation regimes. The plains north and south of the lake are dominated by clastic input related to climate variations and uplift/erosion, whereas the steep western and eastern margins are controlled by recent tectonics. Furthermore, no evidence for a much higher lake-level during the Holocene was found in the plains north and south of the lake, except rare temporary floodings. This is supported by mappings of the limestone cliffs around Lake Ohrid, which yielded no evidence for abrasional platforms or notches as indicators for past highstands.  相似文献   

Shock Wave Interactions in Rock Blasting: the Use of Short Delays to Improve Fragmentation in Model-Scale     

Daniel Johansson  Finn Ouchterlony 《Rock Mechanics and Rock Engineering》2013,46(1):1-18

A series of detailed small-scale tests have been made to investigate the use of short delays to promote better fragmentation caused by shock wave interactions. The block design had a size of 650/660 × 205 × 300 mm (L × W × H) and two rows with five Ø 10-mm blastholes in each row. The spacing (S) and burden (B) were 110 and 70 mm, respectively, giving an S/B ratio of 1.6. The results showed no distinct differences or high improvements of the fragmentation when the delays were in the time range of interactions compared with no shock wave interactions. The decrease of x ₅₀ (mean size) was around 20 % at a delay time ~1.1 ms/m burden compared with longer delays like 2 ms/m. A statistical analysis of the results has been made to evaluate the minimum at short delays and it is not significant.  相似文献   

Tsunami impact assessment: development of vulnerability matrix for critical infrastructure and application to Christchurch,New Zealand     

Williams  James H.  Wilson  Thomas M.  Horspool  Nick  Lane  Emily M.  Hughes  Matthew W.  Davies  Tim  Le  Lina  Scheele  Finn 《Natural Hazards》2019,96(3):1167-1211

Natural Hazards - Tsunamis can have severe impacts on society. In addition to casualties and damage to buildings, they can also damage and disrupt critical infrastructure. To support effective risk...  相似文献   

The polarization of continuum radiation in sunspots     

G. D. Finn  J. T. Jefferies 《Solar physics》1974,39(1):91-106

Expressions are derived for the Stokes parameters of light scattered by a layer of free electrons and hydrogen atoms in a sunspot. A physically reasonable sunspot model was found so that the direction of the calculated linear polarization agrees reasonably with observations. The magnitude of the calculated values of the linear polarization agrees generally with values observed in the continuum at 5830 Å. Circular polarization in the continuum also accompanies electron scattering in spot regions; however for commonly accepted values of the longitudinal magnetic field, the predicted circular polarization is much smaller than observed.  相似文献   

Media,performance, and pastpresents: authenticity in the digital age     

Katrinka Somdahl-Sands  John C. Finn 《GeoJournal》2015,80(6):811-819

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Adaptive morphologies and guild structure in a high-diversity bivalve fauna from an early Campanian rocky shore, Ivö Klack (Sweden)     

Anne Mehlin Sørensen  Finn SurlykJohn W.M. Jagt 《Cretaceous Research》2012,33(1):21-41

The bivalve fauna from a late early Campanian rocky shore at Ivö Klack (southern Sweden), comprises just over sixty species, a very high diversity in comparison to other Late Cretaceous and modern rocky shore bivalve assemblages. This high diversity is here considered to represent a reliable census of the fauna; only in part can it be explained by the cumulative effect of generations of bivalves inhabiting this coastal environment. The high density and diversity and the wide range of shell morphologies allow interpretation of different modes of life in this variable environment with many contrasting habitats. Study of the functional morphology of bivalve shells and comparison with extant relatives has resulted in a subdivision of the fauna into seven guilds and five habitats. The bivalve fauna represents a within-habitat, time-averaged assemblage to which none of the species was introduced from adjacent environments. It includes some of the most northerly known, very small rudistid bivalves, in addition to the oldest known occurrences of Mytilus and Barbatia in association with rocky shores. Bivalves constituted the most important invertebrate group inhabiting the late early Campanian rocky shore at Ivö Klack, in terms of diversity, density and biomass.  相似文献   

Upper Campanian-Maastrichtian nannofossil biostratigraphy and high-resolution carbon-isotope stratigraphy of the Danish Basin: Towards a standard δC curve for the Boreal Realm     

Nicolas Thibault  Rikke HarlouNiels Schovsbo  Poul SchiølerFabrice Minoletti  Bruno GalbrunBodil W. Lauridsen  Emma SheldonLars Stemmerik  Finn Surlyk 《Cretaceous Research》2012,33(1):72-90

High-resolution carbon isotope stratigraphy of the upper Campanian-Maastrichtian is recorded in the Boreal Realm from a total of 1968 bulk chalk samples of the Stevns-1 core, eastern Denmark. Isotopic trends are calibrated by calcareous nannofossil bio-events and are correlated with a lower-resolution δ¹³C profile from Rørdal, northwestern Denmark. A quantitative approach is used to test the reliability of Upper Cretaceous nannofossil bio-events and provides accurate biohorizons for the correlation of δ¹³C profiles. The Campanian-Maastrichtian boundary (CMB) is identified through the correlation of dinoflagellate biostratigraphy and δ¹³C stratigraphy between Stevns-1 and the Global boundary Standard Stratotype-section and Point at Tercis les Bains (SW France), allowing the identification of new chemical and biostratigraphic markers that provide a precise placement of the stage boundary on a regional scale. The boundary interval corresponds to the third phase of a stepwise 0.8‰ negative δ¹³C excursion, lies in calcareous nannofossil subzone UC16d^BP, and encompasses the last occurrence of nannofossil Tranolithus stemmerikii and first occurrence of nannofossil Prediscosphaera mgayae. Fifteen δ¹³C events are defined and correlated to sixteen reliable nannofossil biohorizons, thus providing a well-calibrated standard high-resolution δ¹³C curve for the Boreal Realm.  相似文献   

Late Cretaceous scleractinian corals from the rocky shore of Ivö Klack, southern Sweden, including some of the northernmost zooxanthellate corals     

Anne Mehlin SørensenSøren Floris  Finn Surlyk 《Cretaceous Research》2011,32(3):259-263

A relatively low diversity coral fauna comprising eight zooxanthellate, three azooxanthellate, and one unidentified species is described from a Late Cretaceous rocky shore at Ivö Klack, southern Sweden. All species, except the solitary azooxanthellate Paracyathus? sp., are represented by one or two specimens only, indicating low preservation potential similar to the aragonite-shelled gastropod fauna from the same locality. The fauna comprises one out of two northernmost zooxanthellate forms known and adds important environmental information to the fauna and depositional conditions of the rocky shore at Ivö Klack.  相似文献   

A method to generalize stream flowlines in small-scale maps by a variable flow-based pruning threshold     

Michael Tinker  Peter Anthamatten  Jeff Simley  Michael P. Finn 《制图学和地理信息科学》2013,40(5):444-457

The aim of this paper is to explore and describe a method of automated generalization designed to produce a map which strikes a balance between cartographic and hydrologic representations. Following a discussion of scholarly literature on generalization, we describe a novel method for automated generalization of hydrographic stream data, using the National Hydrography Data Set (NHDPlus) as an example.

Traditional hydrography shows a fairly uniform density of stream flowlines over space. While this is pleasing to the eye, traditional methods tend to under-represent rivers in humid areas and over-represent them in arid areas. We address this problem through a method in automated generalization to produce a high-quality presentation of hydrographic data, suitable for display as a wall map or in an atlas. Streams are pruned based on a variable flow threshold, derived from the local mean annual precipitation by a regression equation.

After running the model using different parameters, we produce a more satisfactory portrayal of stream networks in the United States that communicates the flow of water through rivers and reflects the regional climate. Specific advantages in generalizing with variable flow threshold include (1) the method allows for fine gradations in output scale; (2) the output maps tend to minimize density variations in the raw data; (3) the subjective criteria are easily derived; and (4) the method can be performed rapidly on large data sets, as long as the stream data has been enriched with reliable flow rates.  相似文献