Prediction of input energy spectrum: attenuation models and velocity spectrum scaling          下载免费PDF全文

F. S. Alıcı  Halûk Sucuoğlu 《地震工程与结构动力学》2016,45(13):2137-2161

  相似文献   

Influence of food web structure on the biochemical composition of seston,zooplankton and recently deposited sediment in experimental freshwater mesocosms     

Béatrice Allard  Michaël Danger  Loïc Ten-Hage  Gérard Lacroix 《Aquatic Sciences - Research Across Boundaries》2011,73(1):113-126

The effects of food web structure on the quantity and biochemical composition of seston, zooplankton and recently deposited sediment in experimental freshwater mesocosms were examined. Food web structure was manipulated by addition of zooplanktivorous fish. Biochemical characterisations were carried out using lipid biomarkers (sterols, fatty acids, chlorophyll-derived compounds and long-chain alkanediols). Fish addition decreased zooplankton biomass and increased seston biomass and deposited sediment through a trophic cascade. Fish presence strongly influenced the biochemical characteristics of seston and sediment. In contrast, food web structure had a minor impact on the lipid biomarker composition of zooplankton. Although the relative abundance of sterols in the different compartments did not differ strongly between treatments, sterol profiles in seston and sediment depended on food web structure. The predominance of Δ⁷-sterols in seston and sediment in the fish treatment indicated a major contribution of Chlorophyceae. In contrast, the distribution of sterols in seston and sediment in the fishless treatment, dominated by cholesterol, indicated a major zooplanktonic input. The distribution of fatty acids and the relative abundance of chlorophyll-derived compounds and long-chain alkanediols agreed with the predominant contribution of phytoplankton or zooplankton to seston and sediment in the two treatments. The relative abundance of bacterial biomarkers suggested that the contribution of bacteria was rather low. The high relative abundance of polyunsaturated fatty acids (PUFAs) and the absence of stanols in sediments suggested low microbial reworking of organic matter in the recently accumulated sediments. The trophic cascade, generated by the addition of fish, increased the relative abundance of PUFAs in deposited organic matter, thus enhancing sediment quality and potential degradability.  相似文献   

Preface: Proceedings of the 5th International Symposium on Lithographic Limestone and Plattenkalk   总被引：1，自引：0，他引：1  

Daniel Marty  Jean-Paul Billon-Bruyat  Christian A. Meyer  Loïc Costeur  Basil Thüring 《Swiss Journal of Geoscience》2011,104(1):1-29

Magmatic rocks from the pre-Mesozoic basements of the Sambuco and Maggia nappes have been dated by U–Pb zircon ages with the LA-ICPMS technique. Several magmatic events have been identified in the Sambuco nappe. The mafic banded calc-alkaline suite of Scheggia is dated at 540 Ma, an age comparable to that of mafic rocks in the Austroalpine Silvretta nappe. The Sasso Nero peraluminous augengneiss has an age of 480–470 Ma, like many other “older orthogneisses” in Alpine basement units. It hosts a large proportion of inherited zircons, which were dated around 630 Ma, a Panafrican age indicating the Gondwanan affiliation of the Sambuco basement. The calc-alkaline Matorello pluton yielded ages around 300 Ma, similar to numerous Late Carboniferous intrusions in other basement units of the Lower Penninic (Monte Leone, Antigorio, Verampio) and Helvetic domains (Gotthard and other External Crystalline Massifs). Associated lamprophyric dykes are slightly younger (300–290 Ma), like similar dykes sampled in gneiss blocks included in the sedimentary cover of the underlying Antigorio nappe (290–285 Ma). The Cocco granodiorite and Rüscada leucogranite, both intruding the basement of the neighbouring Maggia nappe, yielded ages of ca. 300–310 Ma, identical within errors to the age of the Matorello pluton. They are significantly older than former age determinations. This age coincidence, coupled with remarkable petrologic similarities between the Cocco and Matorello granodiorites, strongly suggests paleogeographic proximity of the Sambuco and Maggia nappes in Late Carboniferous times. In recent publications these two nappes have been interpreted as belonging to distinct Mesozoic paleogeographic domains: “European” for Sambuco and “Briançonnais” for Maggia, separated by the “Valais” oceanic basin. In this case, the similarity of the Matorello and Cocco intrusions would demonstrate the absence of any significant transcurrent movement between these two continental domains. Alternatively, according to a more traditional view, Sambuco and Maggia might belong to a single large Alpine tectonic unit.  相似文献   

A Comparison of Carlin-type Gold Deposits:Guizhou Province,Golden Triangle,Southwest China,and Northern Nevada,USA   总被引：2，自引：0，他引：2  

Jean S.CLINE  John L.MUNTEAN  Xuexiang GU  Yong XIA 《地学前缘》2013,20(1):1-18

  相似文献   

河南省恐龙蛋类型及古生态特征     

周世全  罗铭玖  王德有  张克伟  李俊峰  何萍  周世全 《河南国土资源》1996,(3)

河南省是我国乃至世界上最重要的恐龙蛋化石产地之一，具有含蛋层位多、数量大、类型全、原始状态保存好以及可供研究的Ｋ／Ｔ界线等特点。据初步统计，已有７科、１０属、１９种之多，且与霸王龙、鸭咀龙、蜥脚类及轮藻、孢粉、痕迹化石等共生。本文评述了恐龙蛋化石的分类系统、地层划分与时代、古生态特征及古气候等，并论述了恐龙绝灭的问题。  相似文献   

Geometry of the hemispherical radiometric footprint over plant canopies     

B.?Marcolla  A.?CescattiEmail authorView author&#;s OrcID profile 《Theoretical and Applied Climatology》2018,134(3-4):981-990

Radiometric measurements of hemispherical surface reflectance and long-wave irradiance are required to quantify the broadband albedo and the outgoing thermal radiation. These observations are typically integrated with eddy covariance measurements of sensible and latent heat fluxes to characterize the surface energy budget. While the aerodynamic footprint has been widely investigated, the geometry of the hemispherical radiometric footprint over plant canopies has been rarely tackled. In the present work, the size and shape of the hemispherical radiometric footprint are formalized for a bare surface and in presence of a vegetation cover. For this purpose, four idealized canopies are analyzed and the dependency of the radiometric footprint on leaf area index and canopy height is explored. Besides, the radiometric footprint is compared with the aerodynamic footprint in conditions of neutral stability. It was observed that almost 100% of the hemispherical radiometric signal originates within a distance of a few radiometer heights, while only about 50–80% of the cumulative aerodynamic signal is generated within a distance of about 20 sensor heights. In order to achieve comparable extensions of the footprint areas, hemispherical radiometric measurements should therefore be taken about 6–15 times higher than turbulent flux ones, depending on the vegetation type. The analysis also highlights that the size of the radiative footprint decreases at increasing leaf area index, whereas the aerodynamic footprint shows an opposite behavior. For the abovementioned reasons, this work may support the interpretation of energy flux measurements and the optimal design of eddy covariance stations located in heterogeneous sites.  相似文献   

Changes in storminess and surges in western France during the last century     

Paolo Antonio Pirazzoli  Herv Regnauld  Loïc Lemasson 《Marine Geology》2004,210(1-4):307-323

French meteorological data provide some information on wind direction since 1890. Since 1951, wind speed and direction have been digitised every three hours in many stations. The Brest tide gauge has recorded hourly sea levels since 1860, thus enabling hourly surges to be calculated and studied. This set of data has been organised into a data base and analysed in order to recognize evolution and trends. Strong winds are increasing in frequency in the western part of Brittany and decreasing in Normandy and Pays de Loire. Surges associated with these winds do present a slight decreasing trend. A more precise analysis allows to distinguish between southerly winds, which are slightly decreasing, and strong winds from other directions, which display a more or less important increase in frequency. The analysis shows trends that may be linked to the global circulation pattern, and that result in a new spatial distribution of winds on western France.  相似文献   

The CMEKF Method for Sub-Sea Pipeline Monitoring and Leak Detection     

白莉  岳前进  崔莉  李洪升  金兆玉  王庆国 《中国海洋工程》2004,18(4):527-535

1 .IntroductionIdentificationofaleakingflowlinerepresentsaspecialchallengetoboththeoilandgasindustryandregulators .While ,historically ,thenumberofcasesofshallowwaterreleasefromflowlinesisex tremelysmall,deepwaterflowlinesoperateunderconditionsrarelyencounteredinpreviousdevelopmentschemes .Theremotenessofthedeepwaterpipeline ,coupledwithanumberofcomplexinteractionsbe tweenthereleasedfluidsandthedeepwaterenvironment,effectivelyeliminatesmostexternaldetectionmethods (Scott,1 999) .Thecauseoflea…  相似文献   

A Review of Studies on the Interaction Between Waves and Muddy Bottom     

Zhao Zidan Professor  Doctoral Supervisor  Tianjin University  Tianjin 《中国海洋工程》1992,(2)

This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University.  相似文献   

Along-strike variations of P–T conditions in accretionary wedges and syn-orogenic extension,the HP–LT Phyllite–Quartzite Nappe in Crete and the Peloponnese     

Laurent Jolivet  Fabien Trotet  Patrick Monié  Olivier Vidal  Bruno Goffé  Loïc Labrousse  Philippe Agard  Bad'r Ghorbal 《Tectonophysics》2010,480(1-4):133-148

Syn-orogenic detachments in accretionary wedges make the exhumation of high-pressure and low-temperature metamorphic rocks possible with little erosion. The velocity of exhumation within the subduction channel or the accretionary complex, and thus the shape of P–T paths, depend upon the kinematic boundary conditions. A component of slab retreat tends to open the channel and facilitates the exhumation. We document the effect of slab retreat on the shape of P–T paths using the example of the Phyllite–Quartzite Nappe that has been exhumed below the Cretan syn-orogenic detachment during the Miocene in Crete and the Peloponnese. Data show a clear tendency toward colder conditions at peak pressure and during exhumation where the intensity of slab retreat is larger. This spatial evolution of P–T gradient is accompanied with an evolution from a partly coaxial regime below the Peloponnese section of the detachment toward a clearly non-coaxial regime in Crete.  相似文献