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81.
本文将随机振动的虚拟激励法与拱坝-地基动力相互作用FE-BE-IBE时域模型结合,发展了一个可以考虑多维随机地震动作用下的拱坝动力响应计算模型,并用Monte Garlo方法对模型进行了验证,计算结果表明,地震动分量的相关性对结构的动力响应存在一定影响,合理考虑地震动各方向分量的相关性可以更好地计算实际地震作用下的拱坝动力响应。 相似文献
82.
Angela Marinoni Paolo Laj Pierre Alexandre Deveau Federica Marino Grazia Ghermandi Fabien Aulagnier Hlne Cachier 《Atmospheric Research》2005,74(1-4):565-580
The physical and chemical properties of aerosol particles were investigated at Plan d'Aups, one of the ESCOMPTE sites located in the St. Baume mountain area (700 m a.s.l.), 50 km east of Marseilles (France). The site is ideally located for assessing the vertical and horizontal extent of the pollution plume from the Marseilles–Berre area.Our study showed that polluted air masses from the Marseilles–Berre area are advected to Plan d'Aups in the early afternoon. Average daily concentration of particles reaches up to 40 μg m−3 while 1-h average particle number concentration is greater than 30,000 cm−3. Most of the particle mass is composed of SO42− and organic carbon (OC). The chemical properties of the particles revealed that an additional source, possibly from the industrial area of Gardanne, contributes to the aerosol mass. This last source is characterised by significant emissions of elements, such as Zn, V, Al and Si.In addition to transport, we found that gas-to-particle conversion takes place at the interface between the free troposphere and the boundary layer. We estimated that on average, 30% of the particle number is accounted for by direct nucleation. This is potentially a major aerosol source to the free troposphere. 相似文献
83.
Effect of chemical fertilizers on the fractionation of Cu,Cr and Ni in contaminated soil 总被引:1,自引:0,他引:1
Jie Liu Chang-Qun Duan Yi-Nian Zhu Xue-Hong Zhang Cheng-Xian Wang 《Environmental Geology》2007,52(8):1601-1606
Effect of chemical fertilizers (urea, NH4Cl, Ca(NO3)2, KCl and KH2PO4) on the fractionation of Cu, Cr and Ni was studied by a 4-month incubation experiment. Using sequential extraction procedure,
it was found that the application of fertilizers could change the distribution of Cu, Cr and Ni in the fractions of soil.
Applying urea (CO(NH2)2) significantly decreased the concentrations of Cu, Cr and Ni in water soluble plus exchangeable (WE) fraction, but increased
those in Fe–Mn oxides bound (FM) fraction (p < 0.01). However, application of NH4Cl caused an increase in the WE fraction by 27.7% for Cu, 111.5% for Cr and 20.4% for Ni. The CO(NH2)2 raised the soil pH from 4.51 to 4.96, whereas NH4Cl lowered the pH of soil by 0.44 units. The WE fraction of the three heavy metals was significantly increased, while the
FM fraction was significantly decreased by adding KCl (p < 0.01). Moreover, the supply of KH2PO4 reduced the WE and carbonate bound (CB) fractions of Cu, Cr and Ni in the soil, however, it raised Cu and Ni in the residual
(RS) fraction and Cr in the FM fraction. In addition, the mobility index indicated that KCl and NH4Cl increased the mobility of Cu, Cr and Ni in the soil, whereas urea and KH2PO4 decreased the mobility of the three metals in the soil. These results suggest that applying chemical fertilizers does not
only provide plant nutrients, but may also change the speciation and mobility of heavy metals in the soil. 相似文献
84.
Bridge fragility curves, which express the probability of a bridge reaching a certain damage state for a given ground motion parameter, play an important role in the overall seismic risk assessment of a transportation network. Current analytical methodologies for generating bridge fragility curves do not adequately account for all major contributing bridge components. Studies have shown that for some bridge types, neglecting to account for all of these components can lead to a misrepresentation of the bridges' overall fragilities. In this study, an expanded methodology for the generation of analytical fragility curves for highway bridges is presented. This methodology considers the contribution of the major components of the bridge, such as the columns, bearings and abutments, to its overall bridge system fragility. In particular, this methodology utilizes probability tools to directly estimate the bridge system fragility from the individual component fragilities. This is illustrated using a bridge whose construction and configuration are typical to the Central and Southeastern United States and the results are presented and discussed herein. This study shows that the bridge as a system is more fragile than any one of the individual components. Assuming that the columns represent the entire bridge system can result in errors as large as 50% at higher damage states. This provides support to the assertion that multiple bridge components should be considered in the development of bridge fragility curves. The findings also show that estimation of the bridge fragilities by their first‐order bounds could result in errors of up to 40%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
85.
A statistical analysis of the peak acceleration demands for nonstructural components (NSCs) supported on a variety of stiff and flexible inelastic regular moment‐resisting frame structures with periods from 0.3 to 3.0 s exposed to 40 far‐field ground motions is presented. Peak component acceleration (PCA) demands were quantified based on the floor response spectrum (FRS) method without considering dynamic interaction effects. This study evaluated the main factors that influence the amplification or decrease of FRS values caused by inelasticity in the primary structure in three distinct spectral regions namely long‐period, fundamental‐period, and short‐period region. The amplification or decrease of peak elastic acceleration demands depends on the location of the NSC in the supporting structure, periods of the component and building, damping ratio of the component, and level of inelasticity of the supporting structure. While FRS values at the initial modal periods of the supporting structure are reduced due to inelastic action in the primary structure, the region between the modal periods experiences an increase in PCA demands. A parameter denoted as acceleration response modification factor (Racc) was proposed to quantify this reduction/increase in PCA demands. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
86.
化学试剂管理数据库的设计与开发——以华东地质学院化学试剂管理数据库为例 总被引:2,自引:0,他引:2
论述了采用客户/服务器模型设计、实现化学试剂管理数据库的方法和技术。通过网络平台完成院各部门的年度化学试剂申报、统计和管理工作,可以充分发挥校园网的通讯优势。解决了长期存在的化学试剂手工管理所带来的效率低、申报不及时甚至重复申报等问题。 相似文献
87.
The spatial organization of decadal and bidecadal components (fluctuations) of annual rainfall is identified in this research for two regions: (1) southern South America, and (2) southern North America (conterminous USA, southeastern Canada and northern and central Mexico). Findings indicate that these decadal and bidecadal components have highly coherent wave-like spatial organization. Two types of organization of decadal and bidecadal components of annual rainfall were identified: a train of propagating fluctuations and quasi-standing fluctuations. For decadal components, such patterns alternate in time. A widespread change in the spatial organization of decadal component of annual rainfall took place simultaneously in both continents in 1932. The bidecadal component is organized as standing fluctuations in southern North America and as travelling fluctuations in southern South America, The spatial pattern of decadal fluctuations of annual rainfall has 12- and 13-year cycles, and the spatial pattern of bidecadal fluctuations has predominantly 21- and 22-year cycles. 相似文献
88.
地震面波产生的地震动转动分量研究 总被引:7,自引:0,他引:7
本文利用弹性波动理论对地面转动分量,即瑞利(Rayleigh)波和乐夫(Love)波产生的转动分量进行了研究,给出了相应的计算公式和计算方法,特别注意到面波的散射效应对转动分量的影响,并将这一特性引入到转动分量的求取中,使问题的解决更切合于实际,最后选取实际地震记录,利用得到的公式计算出地震面波产生的转动分量。 相似文献
89.
Since the late 1970s, the dynamic range and resolution of strong motion digital recorders have leaped from 65 to 135 dB, opening new possibilities for advanced data processing and interpretation. One of these new possibilities is the calculation of permanent displacement of the ground or of structures, associated with faulting or with non-linear response. Proposals on how permanent displacements could be recovered from recorded strong motion have been published since 1976. The analysis in this paper concludes that permanent displacements of the ground and of structures in the near-field can be calculated provided all six components of strong motion (three translations and three rotations) have been recorded, and the records are corrected for transducer rotation, misalignment and cross-axis sensitivity. 相似文献
90.
农业生态的化学元素分类及其与作物优质高产的关系 总被引:12,自引:0,他引:12
利用国家科学技术成果,并根据国内外研究现状,将103个化学元素分成对作物生长发育、增产起显著作用、起一定作用、起有害作用和起未知作用4个农业生态元素类型,进而论述了它们与作物优质高产的关系。 相似文献