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171.
Scattering of an elastic wave by a cylindrical shell embedded in poroelastic medium is investigated theoretically with the assumption that the shell material is also a porous elastic medium. The porous medium is modellized via Biot's theory and the scattering by cylindrical shell is expressed by the definition of scattering matrix. The normal mode expansion technique is employed for analysing the scattering field, and the asymptotic solutions of displacements, stresses and pore pressure are derived. Two limiting cases‐scattering by a poroelastic cylinder in Biot medium and a elastic cylindrical shell in elastic medium are obtained from the general solutions. The dispersion curves of displacement amplitude at the interface of shell and medium is compared with the case of elastic shell. The scattering amplitude associated with the fast, slow and transverse waves are identified by numerical simulation. Furthermore, the influence of the poroelastic property of shell material on scattering amplitude is analysed. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
172.
A three-dimensional baroclinic shelf sea model was employed to simulate the seasonal characteristics of the South China Sea (SCS) upper circulation. The results showed that: in summer, an anticyclonic eddy, after its formation between the Bashi Channel and Dongsha Islands in the northeastern SCS, moves southwestward until it disperses slowly. There exists a northward western boundary current along the east shore of the Indo-China Peninsula in the western SCS and an anticyclonic gyre in the southern SCS. But at the end of summer and beginning of autumn, a weak local cyclonic eddy forms in the Nansha Trough, then grows slowly and moves westward till it becomes a cyclonic gyre in the southern SCS in autumn. At the beginning of winter, there exists a cyclonic gyre in the northern and southern SCS, and there is a southward western boundary current along the east shore of the Indo-China Peninsula. But at the end of winter, an anticyclonic eddy grows and moves toward the western boundary after forming in the Nansha Trough. The eddy‘s movement induces a new opposite sign eddy on its eastern side, while the strength of the southward western boundary current gets weakened. This phenomenon continues till spring and causes eddies in the southern SCS. 相似文献
173.
根据对常德1631年地震事件的史料鉴别,尤其是江陵为典型七度震害这一事实,运用震声传播方向和地光物理场以及地震烈度衰减关系,拟合推断此地震事件的序列主要由安乡北6 3/4级地震、常德北太阳山7级地震、澧县6级地震、大庸6级地震和澧县—安乡6 1/2级地震组成,相应的地震地质背景是江汉—洞庭地区晚更新世以来的剩余形变呈四象限分布。若考虑地震-构造相关分布为“Z”字型,则该地震事件的主控构造——太阳山断裂带东断裂具左旋走滑的力学机制。根据区域地震—构造相关发展过程,常德大震事件可视为1668年郯城8 1/2级地震的前震序列组成部分。 相似文献
174.
大坂山“铬矿物”产出于灰绿色中细粒石英闪长岩中,笔者从区域地质特征、岩石学、岩石化学、地球化学、同位素等方面对石英闪长岩进行了较全面的研究后认为,该套岩石成因为壳幔混合型,构造环境为北祁连加里东洋盆收缩阶段板块俯冲作用下形成的火山弧,岩石成岩时代为早奥陶世,铬矿物形成深度约30km,受区域性岩石圈断裂带控制。 相似文献
175.
波吉卵囊藻的固定化培养及利用 总被引:3,自引:0,他引:3
以褐藻酸钙为固定化载体,探讨了胶球直径、不同接种量、CaCl2溶液浓度、褐藻酸钠浓度等条件对波吉卵囊藻(Oocystisborgei)固定化培养及对养殖水体水质的影响。结果表明:波吉卵囊藻固定化培养的最好条件是微藻接种量为1×106 mL-1,CaCl2溶液的质量浓度为30g/L,褐藻酸钠溶液的质量浓度为20g/L。在此条件下制备的固定化藻珠,波吉卵囊藻的生物量从1 83×10-2 mg/粒增加到17. 46×10-2 mg/粒,增加了近10倍,生长率相对较高,证明了它的生理活性不会因固定化而受干扰。引入固定化的波吉卵囊藻不但可以降低养殖水体中氨氮、亚硝酸氮等有害因子的浓度,还能提高水中溶解氧含量,使水体环境长时间处于良好的动态平衡状态。 相似文献
176.
This study investigated the spatial scaling properties of Canadian flood flows, namely, annual maximum mean 1‐, 5‐ and 7‐day flows using both the product moments (PMs) and probability weighted moments (PWMs). Both approaches demonstrate that flood flows in climatic regions 1 (Pacific), 2 (South British Columbia mountains), 3 (Yukon and northern British Columbia), 6 (Northeastern forest), 7 (Great Lakes and St. Lawrence rivers), 8 (Atlantic), and 10 (Arctic tundra) exhibit simple scaling with scaling exponent θ/H close to 0·90, while flood flows in regions 4 (Prairie provinces), 5 (Northwestern forest), and 9 (Mackenzie) does not with scaling exponent θ/H close to 0·50. The plots of coefficient of variations of flood flows versus drainage area indicate that Cv remains almost constant in regions 1, 2, 3, 6, 7, 8, and 10, while it decreases as drainage area increases in regions 4, 5, and 9. These results demonstrate that the index flood method is applicable in climatic regions 1, 2, 3, 6, 7, 8, and 10, while it is not in climatic regions 4, 5, and 9. The physical backgroud of the simple scaling of flood flows in most Canadian climatic regions is that snowmelt or rain‐on‐snow runoff is a dominant flood‐generating mechanism across the country. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
177.
烃气测量法在锡、金、铜、铅锌等金属矿床找矿中得到了广泛应用,而该技术在花岗岩型铀矿找矿中的应用鲜有报道。本文对桂北376铀矿床已知矿体开展了烃气测量试验,结果显示:相较于其他金属矿,该铀矿区花岗岩和土壤中总烃含量极低,而且花岗岩总烃含量(平均19.42μL/kg)高于上覆土壤(平均6.32μL/kg)。花岗岩中U与多数烃气组分呈负相关,与重烃呈正相关,重烃在U迁移过程中作用强于轻烃;花岗岩烃气标准化配分模式以C1、iC4和C2-正异常为特征;铀矿化程度与iC4/nC4、(C1+iC4+C2-)/(C2+C3+nC4)及C2-/C3-比值呈正相关,与C2+/∑C比值呈负相关等可为寻找铀矿提供依据。3... 相似文献
178.
Acta Geotechnica - Electro-osmotic permeability is a very important parameter in soil drainage and electrochemical remediation. The present widely used equation for calculating the electro-osmotic... 相似文献
179.
<正>The Geological Mineral Exploration Institute No.8 in Inner Mongolia,China has recently discovered a new super-large big flake graphite ore deposit named the Chahanmuhulu graphite deposit.A total of eleven graphite orebodies were delineated in the deposit,with orebodies No.III and IV being dominant.The orebodies extend 85–1630 m along the strike,and have an oblique depth of 563 相似文献
180.
Climate Dynamics - A regional climate model, WRF (Weather Research and Forecasting model), was set-up and fine-tuned to simulate the possible impacts of climate change to the Mackenzie River Basin... 相似文献