An analytical solution for wave-induced seabed response in a multi-layered poro-elastic seabed     

Xiang-Lian Zhou  Bin Xu  Yao-Liang Li 《Ocean Engineering》2011,38(1):119-129

In this study, a new analytical solution for the wave-induced seabed response in a multi-layered poro-elastic seabed is developed. The seabed is treated as a multi-layered porous medium and characterized by Biot’s theory. The displacements of the solid skeleton and the pore pressure are expressed in terms of two scalar potentials and one vector. Then, the Biot’s dynamic equation can be solved using Fourier transformation and reducing to Helmholtz equations. To obtain the general solutions for the multi-layered poro-elastic seabed in the frequency-wave-number domain, the transmission and reflection matrices (TRM) method is used to form the equivalent stiffness. Using the boundary conditions and continuous conditions, the frequency-wave-number domain solutions are obtained. Finally, the time-space domain solutions for the multi-layered poro-elastic seabed are obtained by means of the inverse Fourier transformation with respect to the horizontal coordinate. Based on the new solution, a parametric study is carried out to examine the effects of soil characteristics (number of layers, permeability and shear modulus) and wave characteristics (water depth and wave steepness) on seabed responses. The results indicate that the seabed response is affected significantly by permeability, shear modulus and relative water depth.  相似文献   

Spectroscopy of Yamato 984028     

M.D. Dyar  T.D. Glotch  M.D. Lane  B. Wopenka  J.M. Tucker  S.J. Seaman  G.J. Marchand  R. Klima  T. Hiroi  J.L. Bishop  C. Pieters  J. Sunshine 《Polar Science》2011,4(4):530-549

Comprehensive spectroscopic characterization of interior and exterior chips of the lherzolitic shergottite Y-984028 has been performed using results from six techniques. Data from UV–visible–near-IR reflectance spectra, thermal (mid-IR) emission spectra, attenuated total reflectance (ATR) spectra, transmission FTIR spectra, Raman microprobe spectra, and Mössbauer spectra of whole rock and mineral separates from this meteorite are integrated and compared. Five of these analytical techniques accurately determined the ～Fo₆₅ composition of the olivine within ±10 mol%. Both transmission FTIR and ATR spectra show broad features near 3500 cm^?1 indicating the presence of OH/H₂O that does not arise from surface water adsorption. The brown color of the Y-984028 olivine is likely due to the presence of nanophase metallic iron particles (npFe⁰) dispersed throughout the olivine during a major shock event on Mars. Y-984028 olivine also contains a significant amount of Fe³⁺, but this cannot be distinguished from Fe³⁺ that is present in pyroxene and possibly clay minerals. This meteorite and the nakhlite MIL03346 are the two most oxidized of the SNC meteorites studied to date, with Fe³⁺ contents consistent with high-temperature equilibration near the QFM oxygen buffer.  相似文献   

Extrinsic and intrinsic mode of hydrogen occurrence in natural olivines: FTIR and TEM investigation     

N. R. Khisina  R. Wirth  M. Andrut  A. V. Ukhanov 《Physics and Chemistry of Minerals》2001,28(5):291-301

Olivine crystals from two mantle nodules in kimberlites (pipe Udachnaya and pipe Obnazennaya, Yakutiya, Siberia) were investigated using EMP, TEM, AEM and FTIR techniques to determine the mode of hydrogen occurrence in olivine. Olivine contains three types of nanometer-sized inclusions: “large” inclusions of hexagonal-like shape up to several hundred nm in size (1), lamellar defects (2) and small inclusions of hexagon-like shape up to several 10?nm in size (3). Lamellar defects and small inclusions are considered to be a “hydrous” olivine. All three types of inclusions contain OH^? or water, but they are different with respect to their phase composition. In “large” inclusions (1) hydrous magnesium silicates, such as serpentine?+?talc (“kerolite”?) and 10-Å phase?+?talc were identified. Lamellar defects (2) and small inclusions (3) are depleted in Mg and Fe compared to the olivine matrix, while the silica content is the same as that of olivine. Modulations in the periodicity of the olivine structure are observed in SAED patterns and HREM images of (2) and (3). The superperiodicity can be referred to OH^?-bearing point defect ordering in the olivine structure. If this is the case, the material of both lamellar defects and small inclusions can be assumed to be a “hydrous olivine” Mg_{2– x} v _x SiO₄H_{2 x} with a cation-deficient olivine crystal structure. Thus, both an extrinsic mode of hydrogen occurrence in olivine, such as nanometer-sized inclusions of OH^?-bearing magnesium silicates, and an intrinsic mode of hydrogen incorporation into the olivine structure, such as “hydrous olivine” in itself, were found. The data obtained here show that the OH absorption bands observed in olivine spectra at 3704(3717) and 3683(3688) cm^?1 can be unambiguously identified with serpentine; the band at 3677(3676) cm^?1 can be associated with talc. The absorption bands observed at 3591 and 3660?cm^?1 in olivine match those of the 10-Å phase at 3594, 3662 and 3666?cm^?1.  相似文献   

Cation ordering in omphacite and effect on deformation mechanism and lattice preferred orientation (LPO)   总被引：1，自引：0，他引：1  

Frank E. Brenker  Dave J. Prior  Wolfgang Friedrich Müller 《Journal of Structural Geology》2002,24(12)

We present microstructural data and lattice preferred orientations (LPOs) of omphacites from a suite of eclogites, from the Adula/Cima Lunga nappe (Central Alps). Our work shows a surprisingly strong correlation between the measured LPO and the ordering state of cations in omphacite. Estimates of deformation temperature from metamorphic petrology, together with measured omphacite compositions and LPOs, determine the field (ordering state), on the omphacite phase diagram, into which each sample falls. LPOs dominated by L-type and S-type signatures are developed in samples that fall in the P2/n field (ordered structure) and C2/c field (disordered structure), respectively.Dislocations with b=1/2−110 or b=[001] are observed in the transmission electron microscope (TEM) in all samples. The former change from a perfect dislocation in the C2/c structure to a partial in P2/n. Any movement of a partial dislocation requires the formation or growth of a stacking fault. Furthermore, in order to pass an obstacle a partial dislocation has to constrict to a unit dislocation. The energy to form a constriction is high in omphacite due to the large separation width. Thus, the activity of the b=1/2−110 dislocation is hindered in the P2/n structure relative to the C2/c structure, which change the balance between the two and might give rise to the different LPOs.  相似文献   

BPL脉位调制方案及数据传送     

吴海涛  边玉敬 《时间频率学报》2000,23(2):102-109

实现BPL长波信道能力扩展的一个重要技术环节是对组重复间隔（GRI）脉冲的脉位调制,在将信源消息变成脉位调制电平的数据传输过程中,还有一系列的信号格式转换,提出了实现脉位调制的若干方法,探讨了数据流的详细传送过程并给出了相应的软件。  相似文献   

2013年1月京津唐地区霾事件气溶胶单颗粒形貌及硫酸盐化特征     

王文华  邵龙义  李泽熙  郭茜  侯聪  幸娇萍  赵承美 《岩石矿物学杂志》2015,34(6):914-924

2013年1月华北地区经历了重霾过程,为研究其污染特征,使用透射电子显微镜(TEM)及能谱(EDX)对北京、唐山和天津晴天和霾天气下气溶胶单颗粒基本形貌和硫酸盐化特征进行了分析。结果表明,华北地区气溶胶单颗粒包括矿物颗粒、硫酸盐颗粒、金属氧化物、烟尘集合体、有机颗粒和飞灰,仅在天津市样品中发现少量的Na Cl颗粒。对单颗粒的元素组成进行统计表明,华北地区晴天以富Si颗粒为主(31.0%),其次为富Ca颗粒(18.3%)、富Fe颗粒(14.1%)、富Cl颗粒(12.2%)等,霾天以富S颗粒为主(47.4%),其次为富Si颗粒(21.1%)和富Fe颗粒(13.4%)等。霾天气富Ca颗粒明显减少,同时在含S较高的颗粒中也含有Ca、K等元素,说明大气中含Ca、K等碱性矿物对雾水酸性有一定的缓冲作用。不同天气含S颗粒差异较大,霾天气明显高于晴天,S/Ca平均值在霾天明显较高,且大于0.8,说明在一定的SO2浓度下,大气湿度越大,硫酸盐化现象越明显,生成大量的硫酸铵盐。  相似文献   

Fluid flow dynamics under location uncertainty     

Etienne Mémin 《地球物理与天体物理流体动力学》2014,108(2):119-146

We present a derivation of a stochastic model of Navier Stokes equations that relies on a decomposition of the velocity fields into a differentiable drift component and a time uncorrelated uncertainty random term. This type of decomposition is reminiscent in spirit to the classical Reynolds decomposition. However, the random velocity fluctuations considered here are not differentiable with respect to time, and they must be handled through stochastic calculus. The dynamics associated with the differentiable drift component is derived from a stochastic version of the Reynolds transport theorem. It includes in its general form an uncertainty dependent subgrid bulk formula that cannot be immediately related to the usual Boussinesq eddy viscosity assumption constructed from thermal molecular agitation analogy. This formulation, emerging from uncertainties on the fluid parcels location, explains with another viewpoint some subgrid eddy diffusion models currently used in computational fluid dynamics or in geophysical sciences and paves the way for new large-scales flow modeling. We finally describe an applications of our formalism to the derivation of stochastic versions of the Shallow water equations or to the definition of reduced order dynamical systems.  相似文献   

Rock fracture compliance derived from time delays of elastic waves     

M. Möllhoff  C.J. Bean  P.G. Meredith 《Geophysical Prospecting》2010,58(6):1111-1122

The purpose of this study is to compare the reliability of various methods of estimating normal rock fracture compliance from elastic wave measurements. We compare ultrasonic through‐transmission laboratory measurements for a smooth fracture in a Westerly granite specimen with numerical simulations and analytical solutions. The focus is on deriving compliance from time delays. The influence of specimen and source transducer width was constrained using numerical wave simulations. We find that measured ultrasonic phase delays are better suited to estimate the fracture compliance than group delays. Using the frequency domain instead of the time domain increases the accuracy of the fracture compliance estimates. We further show that for cases where precise phase delay measurements are unavailable, employing first break times in conjunction with numerical simulations can be considered as an alternative.  相似文献   

西气东输二线某隧道南口地质安全评价研究   总被引：1，自引：0，他引：1       下载免费PDF全文

颜宇森  雷海英 《水文地质工程地质》2010,37(2):120-124

对西气东输二线工程新疆果子沟段某隧道南口进行实地调查,查明隧道工程区及其周围的自然地理、地质环境条件,同时调查隧道工程区存在的地质隐患类型、分布、规模、危险状态等因素,分析评价其对隧道施工安全的影响,最终根据地质安全评价结果,提出消除或减弱地质隐患的防治对策和建议。  相似文献   

多种传输方式在青海数字地震台网中的应用     

郭葆庆  孟鑫 《高原地震》2010,22(1):50-53

如何保障数据实时、连续的传输是数字地震台网运行的重要工作,本文就青海省数字地震台网所采用的几种传输方式进行了简单说明。经过近2年的运行,说明这几种传输方式在青海数字地震台网运行过程中经受住了考验,保证了台网的正常运行,同时也为以后的数据传输方式积累了经验。  相似文献