人体泌尿系统结石及人发成分分析的意义

利用红外光谱分析法对尿路结石进行了物相分析,并用原子吸收分光光度法测定了结石和发样的微量元素,根据结石的物相特征、微量元素含量以及与人体发样微量元素含量进行对比分析,探讨了尿路结石的成因、影响因素及预防措施。     

Geometric effects resulting from the asymmetry of dipping fault: Hanging wall/ footwall effects

Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rupture distance Drup and the seismogenic distance Dseis. Then, using Drup, Dseis and Drms, the hanging wall/footwall effects on the peak ground acceleration (PGA) during the 1999 Chi-Chi earthquake are evaluated by regression analysis. The logarithm residual shows that the PGA on hanging wall is much greater than that on footwall at the same Drup or Dseis when the Drup or Dseis is used as site-to-source distance measure. In contrast, there is no significant difference between the PGA on hanging wall and that on footwall at the same Drms when Drms is used. This result confirms that the hanging wall/footwall effect is mainly a geometric effect caused by the asymmetry of dipping fault. Therefore, the hanging wall/footwall effect on the near-fault ground motions can be ignored in the future attenuation analysis if the root-mean-square distance Drms is used as the site-to-source distance measure.     

A novel technique for detection of the toxic dinoflagellate, Karenia brevis, in the Gulf of Mexico from remotely sensed ocean color data

Karenia brevis, a toxic dinoflagellate that blooms regularly in the Gulf of Mexico, frequently causes widespread ecological and economic damage and can pose a serious threat to human health. A means for detecting blooms early and monitoring existing blooms that offers high spatial and temporal resolution is desired. Between 1999 and 2001, a large bio-optical data set consisting of spectral measurements of remote-sensing reflectance (R_rs(λ)), absorption (a(λ)), and backscattering (b_b(λ)) along with chlorophyll a concentrations and K. brevis cell counts was collected on the central west Florida shelf (WFS) as part of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) and Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) programs. Reflectance model simulations indicate that absorption due to cellular pigmentation is not responsible for the factor of ∼3–4 decrease observed in R_rs(λ) for waters containing greater than 10⁴ cells l⁻¹ of K. brevis. Instead, particulate backscattering is responsible for this decreased reflectivity. Measured particulate backscattering coefficients were significantly lower when K. brevis concentrations exceeded 10⁴ cells l⁻¹ compared to values measured in high-chlorophyll (>1.5 mg m⁻³), diatom-dominated waters containing fewer than 10⁴ cells l⁻¹ of K. brevis. A classification technique for detecting high-chlorophyll, low-backscattering K. brevis blooms is developed. In addition, a method for quantifying chlorophyll concentrations in positively flagged pixels using fluorescence line height (FLH) data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) is introduced. Both techniques are successfully applied to Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and MODIS data acquired in late August 2001 and validated using in situ K. brevis cell concentrations.     

兰州市区场地地面与基岩地震动峰值加速度对应关系研究

根据兰州市区黄河阶地特征及黄土层覆盖厚度,对兰州市场地划分了3个分区,选用兰州市区156个满足场地地震反应条件的地震钻孔资料,对每个工程场地合成3组相互独立的基岩加速度输入时程,进行土层地震反应分析,对各个工程场地地面与基岩地震动峰值加速度的对应关系进行研究,结果表明I区内的工程场地地面与基岩地震动峰值加速度比值为1.120,Ⅱ区为1.320,Ⅲ区为1.531,平均均方根误差为0.083。     

微波消解-原子吸收法初步分析葛根中微量元素与种植土质的相关性

采用微波消解-原子吸收光谱法测定葛根及其种植土壤中Cu、Fe、Zn、Mn、Ca和Mg等6种微量元素的含量。葛根中微量元素含量与种植土质的初步相关分析结果表明,葛根中6种微量元素含量丰富,其中Fe、Ca和Mg的含量较高;黄土土壤种植的葛根微量元素含量较黑土高。实验结果可为进一步开发葛根优良品种和平衡施肥提供科学信息和依据。     

Effects of mining-induced seismic events on a deep underground mine

The performance of an underground excavation at the Lucky Friday Mine that was subjected to repetitive episodes of mining-induced seismic activities is assessed. Field measurements indicate that an underground excavation may respond to mining-induced seismicity with step changes in displacement of the rock mass around the excavation or step changes in excavation closures. However, step changes in displacement or closure were also observed without the presence of mine seismic events. This behavior may be explained using the concept of stick-slip on joints or bedding planes within the rock mass. The stick-slip mechanism is believed to be controlled by the state of stresses at a joint or bedding plane. Through this mechanism, joint displacement is accumulated in a progressive fashion leading to a weakening of rock mass around an excavation. As a result, the excavation becomes less stable and therefore is more susceptible to seismic impacts. The concept of using peak particle velocity to assess damage threshold for underground excavations may not be conservative when considering the effect of rock mass fatigue.     

北京地区不同超越概率水准下基岩峰值加速度分析

基于中国地震动参数区划图、华北平原地震带和汾渭地震带地震活动性参数、华北地区地震动参数衰减关系,计算北京地区50年、70年、100年不同超越概率水准下基岩峰值加速度.并分析不同年限各超越概率水准下的峰值加速度与该年限超越概率10％的峰值加速度比值,发现各计算格点的比值普遍偏小,按照当前抗震设防标准,所考虑的地震作用偏于保守且安全.     

基于地震动参数的城市建筑物震害模拟——以兰州市城关区为例

首先利用最短断层法烈度衰减模型分别模拟两次地震的地震动参数空间分布,并通过与实际地震的极震区对比,验证该模型模拟地震烈度的可靠性.然后,基于模拟的地震烈度空间分布和建筑物的结构类型、层高等信息,采用结构弹塑性时程分析方法对兰州市城关区建筑物进行三维震害模拟.研究结果表明:最短断层法是一个模拟历史地震烈度空间分布较好的模...     

黏声介质最小平方逆时偏移

介质的黏滞性是普遍存在的.黏滞性介质中的真振幅成像需要校正由介质的黏滞性引起的振幅衰减与速度频散,然而常规的反Q偏移方法存在不稳定问题.本文在反演的框架下求解黏声介质成像问题,在有效避开不稳定的同时实现真振幅成像.首先将波动方程线性化,并依此建立黏声介质最小平方逆时偏移（LSRTM）的目标函数;然后推导波动方程伴随算子,并在此基础上借助伴随状态法推导迭代求解的具体算法;最后通过引入动态相位编码技术将计算量降至与常规逆时偏移相同的数量级.该方法在真振幅成像过程中考虑了介质黏滞性的影响,更接近实际情况,具有更好的振幅保持性.相对于常规逆时偏移,该方法能够自动压制成像噪声,具有更高的成像分辨率及精度.通过模型试算验证了方法的正确性.     

A simple procedure to approximate slip displacement of freestanding rigid body subjected to earthquake motions

A simple calculation procedure for estimating absolute maximum slip displacement of a freestanding rigid body placed on the ground or floor of linear/nonlinear multi‐storey building during an earthquake is developed. The proposed procedure uses the displacement induced by the horizontal sinusoidal acceleration to approximate the absolute maximum slip displacement, i.e. the basic slip displacement. The amplitude of this horizontal sinusoidal acceleration is identical to either the peak horizontal ground acceleration or peak horizontal floor response acceleration. Its period meets the predominant period of the horizontal acceleration employed. The effects of vertical acceleration are considered to reduce the friction force monotonously. The root mean square value of the vertical acceleration at the peak horizontal acceleration is used. A mathematical solution of the basic slip displacement is presented. Employing over one hundred accelerograms, the absolute maximum slip displacements are computed and compared with the corresponding basic slip displacements. Their discrepancies are modelled by the logarithmic normal distribution regardless of the analytical conditions. The modification factor to the basic slip displacement is quantified based on the probability of the non‐exceedence of a certain threshold. Therefore, the product of the modification factor and the basic slip displacement gives the design slip displacement of the body as the maximum expected value. Since the place of the body and linear/nonlinear state of building make the modification factor slightly vary, ensuring it to suit the problem is essential to secure prediction accuracy. Copyright © 2006 John Wiley & Sons, Ltd.