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31.
Gökhan Demir 《Natural Hazards》2018,91(1):133-153
Numerical modelling techniques enable forcing function at the point of contact in a hail impact to be predicted, but many models available in commercial software have not been verified by experiments. A recently developed deterministic model is only able to simulate the impact action of an idealised spherical hailstone. Results recorded from the impact testing of non-spherical simulated hail ice specimens show wide scatters and are different to spherical specimens. A stochastic model has been developed in this study to incorporate the variability of the modelling parameters representing the behaviour of non-spherical ice specimens and to generate time histories of contact force for given impact scenarios. A probabilistic model which was developed previously to provide predictions of the distribution of the size of hailstones in a severe category hailstorm has also been further developed to provide predictions of the maximum contact force values in probabilistic terms. For any given pre-defined forcing function denting into the surface of a steel plate can be estimated by finite element analysis or experimentally on a test machine. The new knowledge base introduced in this paper can be used by manufacturers and designers to re-assess existing products and in making improvements to future installations taking into account cost–benefit considerations. 相似文献
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Theoretical and Applied Climatology - In the present study, we aimed to understand the current condition of land suitability and how climate change will affect its suitability for rice paddy... 相似文献
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Abdullah Kaygusuz Ferkan Sipahi Nurdane Ilbeyli Mehmet Arslan Bin Chen Emre Aydinakir 《地学前缘(英文版)》2013,4(4):423-438
A series of Cretaceous plutons is present in the eastern Pontides of northeastern Turkey.The Turnagl intrusion is the least studied and,thus,the least understood plutons in the orogen.This intrusion consists of hornblende-biotite granodiorites emplaced at 78 Ma based on LA-ICP-MS U-Pb zircon dating.It is of sub- alkaline affinity,belongs to the medium- to high-K calc-alkaline series,and displays features typical of Itype granites.The rocks of the intrusion are enriched in large-ion lithophile elements and light rare earthelements with negative Eu anomalies(Eu/Eu*= 0.69-0.82),but are deficient in high-field-strength elements.They have a small range of (87Sr/86Sr)i(0.7060-0.7063),εNdi(-2.6 to -3.1),and δ18O(+8.1 to +9.1) values.Their Pb isotopic ratios are 206Pb/204Pb = 18.63-18.65,207Pb/204Pb = 15.62-15.63,and 208Pb/204Pb = 38.53-38.55.The fractionation of plagioclase,hornblende,and Fe-Ti oxides had key functions in the evolution of the Tumagl intrusion.The crystallization temperatures of the melts ranged from 758 to 885℃ as determined by zircon and apatite saturation thermometry.All these characteristics,combined with the low values of K2O/Na2O and(Na2O + K2O)/(FeOt+MgO + TiO2),as well as the high values of (CaO + FeOt + MgO + TiO2).suggest an origin by dehydration melting from a metabasaltic lowercrustal source. 相似文献
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Sukran Akkus Tulin Bal Nagihan M. Karaaslan Emre Yaman Ersin Kilinc Mehmet Yaman 《洁净——土壤、空气、水》2013,41(12):1229-1234
Five‐step sequential extractions were employed to fractionation of Ni, Cr and Cu in soil polluted by anthropogenic activities and determine the mobility of the metals. Twelve samples were collected on an agricultural area that was located near an airport and intercity roads in Elazig‐Turkey. Exchangeable, organically bounded, carbonate bounded, adsorbed species on Fe and Mn oxides and residual species (except silicates) of Ni, Cr and Cu were extracted into solution by using CaCl2, Na4P2O7, Na2EDTA, NH2OH–HCl and HNO3–H2O2, respectively. Mobile metal concentrations in fractions and total recoverable in soils were determined by using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Total recoverable Ni, Cr and Cu concentrations were in the range of 40–119, 45–126 and 23–72 mg kg?1, respectively. It was observed that total concentrations of metals in some of the samples were higher than the permitted values. The sum of the mobile percentages of metals was found to be lower than 50%. The Ni, Cr and Cu percentages for exchangeable species are in the ranges of 0.18–1.64, 0.03–0.59 and 0.42–2.53%, respectively. 相似文献
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O. Dor C. Yildirim T. K. Rockwell Y. Ben-Zion O. Emre M. Sisk T. Y. Duman 《Geophysical Journal International》2008,173(2):483-504
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Natural Hazards - Flood emergency management practices cover various aspects of flooding, such as demography, infrastructure, economy, transportation, and agriculture. Emergency managers and local... 相似文献
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Finite element method (FEM) is effectively used for evaluating roller-compacted concrete (RCC) dams, especially in high seismicity zones. The aim of this study is to investigate the effect of various reservoir lengths on the seismic response of a selected RCC dam under strong ground motion effects. Six different reservoir lengths, the lengths varies from h/2 to 10h (h, the height of dam), are used within finite element models. The hydrodynamic pressure of the reservoir water is modelled with the 2D fluid finite elements based on the Lagrangian approach. The horizontal and vertical components of the 1989 Mw 6.9 Loma Prieta earthquake are utilized in numerical analyses. The non-linear time-history analyses of those six models are investigated by using Drucker-Prager material model. According to the numerical analysis, it is obvious that the seismic behavior of the RCC dams is considerably dependent on the reservoir length. By increasing the length, we have obtained higher displacement values, which exist until the reservoir length reaches the 3h; at increased lengths, the values remain stable. This result proposes that 3h reservoir length is adequate to assess the seismic response of RCC dams. The principal tensile stresses are relatively lower in non-linear analysis compared to linear analyses. However, the principal compression stresses are close to each other in linear and non-linear analyses. The results imply that the non-linear response is influential on the total seismic response of a dam, which cannot be neglected in numerical analysis. 相似文献
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Rob Westaway Hervé Guillou Ali Seyrek Tuncer Demir David Bridgland Stéphane Scaillet Anthony Beck 《International Journal of Earth Sciences》2009,98(3):601-625
We document the staircase of terraces of the River Tigris in the Diyarbakır area of SE Turkey, in the northern Arabian Platform,
and improve control on the ages of these terrace deposits by dating of overlying basalt flows using the unspiked K–Ar technique.
These fluvial terraces are formed of polymict gravel, including clasts derived from the Anatolian metamorphic terrane farther
north as well as of local basalt. At least 9 Tigris terraces have been recognised so far, the highest of which, ∼200 m above
present river level, marks the local transition from stacked deposition to fluvial incision, the timing of which is bounded
between the mid Late Miocene and the Middle Pliocene. Our K–Ar dating indicates a hiatus in fluvial incision in the late Early
Pleistocene, as basalts dated to 1.22 ± 0.02 and 1.07 ± 0.03 Ma overlie Tigris gravels at very similar levels, ∼60–70 m above
the present river. The lower terraces record the subsequent entrenchment of the modern Tigris valley following an increase
in incision rates in the early Middle Pleistocene, evident from the disposition of younger basalt, dated to 0.43 ± 0.02 Ma,
capping fluvial gravel only ∼21–22 m above the present river level. Numerical modelling can account for the observed uplift
history, as the response to coupling between surface processes and induced flow in the lower crust, with the mobile lower-crust
thin (∼5–7 km thick), consistent with the known presence of a thick layer of mafic underplating at the base of the crust beneath
the Arabian Platform.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献