兰州观象台存放台阵汶川M_S8.0强震动记录与分析

兰州观象台存放台阵在汶川特大地震中获取了10组三分量数字强震动加速度记录.本文依据这些实际观测资料研究了黄土场地在地震发生后的自由场地面运动加速度过程及其特征.结果表明在震源、场地和震中距相同情况下,场地上不同测点记录的加速度峰值存在一定程度的差异,较明显地反映了场地地形对EW分向地面自由场加速度的影响.10个测点的峰值加速度(PGA)均显示EW向大于NS向,而垂直向最小;各测点的傅里叶谱值,尤其是在小于1 Hz频段范围内,差异极小.     

泉州地震台数字地震仪台址的地脉动噪声分析

利用2008年泉州台甚宽频带数字地震仪连续48 h和全年每月连续48 h内白天与夜间各连续4 h的地脉动记录,计算5 Hz、5 s和100s的静态地脉动噪声功率谱密度、1/3倍频程1-20Hz带宽各段的平均静态地脉动噪声有效值、1/3倍频程100-30 s带宽各段的平均静态地脉动加速度噪声有效值,以及上述3个频点和2个...     

探索基于地震动峰值加速度的地震灾害评估方法

将福建省面积按0.05°（约5 km）网格离散化后得到4 361个网格点,在地震发生后根据全省台站的监测数据进行计算,每个网格点都能快速得到地震动峰值加速度。利用这些已经赋有地理信息和加速度的网格点对全省乡镇级单位的行政区进行烈度计算和赋值提出一种基于地震动峰值加速度的地震灾害评估方法。     

地下结构对工程场地地震动场的影响

本文以日本神户市地铁大开站为工程背景,应用大型通用有限元ANSYS软件,分别建立了自然条件下的工程场地土层和建有地下车站结构的土层的二维有限元分析模型。计算了基岩一致地震动输入模式下2个土层模型的动力反应。通过将2个土层模型的动力反应进行比较分析,讨论了地下结构对工程场地地震动场的影响。分析结果表明,日本神户地铁大开站的存在对其邻近区域土层的地震反应有影响,但影响有限。     

VIV and galloping of single circular cylinder with surface roughness at 3.0×10≤Re≤1.2×10

Passive Turbulence Control (PTC) in the form of selectively distributed surface roughness is used to alter Flow Induced Motion (FIM) of a circular cylinder in a steady flow. The objective is to enhance FIM's synchronization range and amplitude, thus maximizing conversion of hydrokinetic energy into mechanical energy by oscillator in vortex-induced vibration and/or galloping. Through additional viscous damping, mechanical energy is converted to electrical harnessing clean and renewable energy from ocean/river currents. High Reynolds numbers (Re) are required to reach the high-lift TrSL3 (Transition-Shear-Layer-3) flow regime. PTC trips flow separation and energizes the boundary layer, thus inducing higher vorticity and consequently lift. Roughness location, surface coverage, and size are studied using systematic model tests with broad-field laser visualization at 3.0×10⁴<Re<1.2×10⁵ in the low-turbulence free-surface water-channel of the Marine Renewable Energy Laboratory of the University of Michigan. Test results show that 16° roughness coverage is effective in the range (10°-80°) inducing reduced vortex-induced vibration (VIV), enhanced VIV, or galloping. Range of synchronization may increase or decrease, galloping amplitude of oscillation reaches three diameters; wake structures change dramatically reaching up to ten vortices per cycle. Conversion of hydrokinetic energy to mechanical is enhanced strongly with proper PTC.     

郑州市地下水源热泵应用适宜性与环境影响分析

本文在分析郑州市现有地温空调系统应用的基础上,从水文地质条件、浅层地温场特征、经济效益等方面分析了郑州市地下水源热泵应用的适宜性,研究了热泵运行对地下水环境的影响,认为地下水源热泵应用效果较好,经济社会效益明显,适宜推广应用,为城市地下水源热泵发展应用提供了依据。     

基于OSCAR需求指标对遵义市地面气象观测站网现状分析研究

基于观测系统能力分析和审查工具（OSCAR）选取各气象应用领域对地面观测要素的需求指标,对遵义市地面自动气象观测站网现状进行评估分析,提出相应规划思路,旨在提高地面自动气象站网优化布局,推进气地面象观测业务的高质量发展。     

Timing of advance and basal condition of the Laurentide Ice Sheet during the last glacial maximum in the Richardson Mountains,NWT

This study presents new ages for the northwest section of the Laurentide Ice Sheet (LIS) glacial chronology from material recovered from two retrogressive thaw slumps exposed in the Richardson Mountains, Northwest Territories, Canada. One study site, located at the maximum glacial limit of the LIS in the Richardson Mountains, had calcite concretions recovered from aufeis buried by glacial till that were dated by U/Th disequilibrium to 18,500 cal yr BP. The second site, located on the Peel Plateau to the east yielded a fossil horse (Equus) mandible that was radiocarbon dated to ca. 19,700 cal yr BP. These ages indicate that the Peel Plateau on the eastern flanks of the Richardson Mountains was glaciated only after 18,500 cal yr BP, which is later than previous models for the global last glacial maximum (LGM). As the LIS retreated the Peel Plateau around 15,000 cal yr BP, following the age of the Tutsieta phase, we conclude that the presence of the northwestern margin of the LIS at its maximum limit was a very short event in the western Canadian Arctic.     

Ground penetrating radar inversion in 1-D: an approach for the estimation of electrical conductivity, dielectric permittivity and magnetic permeability

This paper presents a method for inverting ground penetrating radargrams in terms of one-dimensional profiles. We resort to a special type of linearization of the damped E-field wave equation to solve the inverse problem. The numerical algorithm for the inversion is iterative and requires the solution of several forward problems, which we evaluate using the matrix propagation approach. Analytical expressions for the derivatives with respect to physical properties are obtained using the self-adjoint Green's function method. We consider three physical properties of materials; namely dielectrical permittivity, magnetic permeability and electrical conductivity. The inverse problem is solved minimizing the quadratic norm of the residuals using quadratic programming optimization. In the iterative process to speed up convergence we use the Levenberg–Mardquardt method. The special type of linearization is based on an integral equation that involves derivatives of the electric field with respect to magnetic permeability, electrical conductivity and dielectric permittivity; this equation is the result of analyzing the implication of the scaling properties of the electromagnetic field. The ground is modeled using thin horizontal layers to approximate general variations of the physical properties. We show that standard synthetic radargrams due to dielectric permittivity contrasts can be matched using electrical conductivity or magnetic permeability variations. The results indicate that it is impossible to differentiate one property from the other using GPR data.