中国及邻区大地水准面异常的场源深度探讨

利用中国及邻区地形、地震层析成像、沉积层底面、Moho面及岩石层底面资料,正演计算出中国及邻区岩石圈大地水准面异常;再从全阶大地水准面异常中扣除正演模拟得到的岩石圈大地水准面异常与不同阶次波段的大地水准面进行比较,寻求表示中国及邻区地幔物质不均匀的大地水准面异常的最佳阶次为2-60阶. 结果表明,对应于岩石圈的大地水准面异常的重力位球谐函数阶数为61-20阶;下地幔重力位球谐函数阶数为2-6阶;而-60阶重力位球谐函数则表示中国及邻近区域上地幔大地水准面异常.     

Linear combinations of order statistics to estimate the position and scale parameters of the Generalized Pareto distribution

 Ad hoc techniques for estimating the position and the scale parameters of the Generalized Pareto distribution are introduced. The estimators proposed are simple linear combinations of the order statistics: they provide valuable estimates of the parameters of interest, both when the shape parameter is known and when it is unknown (this latter case being of great relevance in practical applications), and show a good performance as well when the sample size is small. The procedures are tested on simulated data, and comparisons with other techniques are shown.     

Magnetic phase diagrams of Mg-, Fe-, (Cu + Ti)- and Cu-substituted braunite Mn<Superscript>2+</Superscript>Mn<Subscript>6</Subscript><Superscript>3+</Superscript>SiO<Subscript>12</Subscript>

 The magnetic behavior of the Jahn-Teller structure braunite, (Mn²⁺ _1−yM _y )(Mn³⁺ _{6− x} M_x)SiO₁₂, is strongly influenced by the incorporation of elements substituting manganese. Magnetic properties of well-defined synthetic samples were investigated in dependence on the composition. The final results are presented in magnetic phase diagrams. To derive the necessary data, ac susceptibility and magnetization of braunites with the substitutional elements M = Mg, Fe, (Cu+Ti) and Cu were measured. Whereas the antiferromagnetic ordering temperature, T _N , of pure braunite is hardly affected by the substitution of nonmagnetic Mg, it is rapidly suppressed by the substitution of magnetic atoms at the Mn positions. Typically for a concentration (x, y) ≥ 0.7 of the substituted elements, a spin glass phase occurs in the magnetic phase diagrams. Additionally, for the braunite system with Fe³⁺ substitutions, we observe in the concentration range 0.2 < x< 0.7 a double transition from the paramagnetic state, first to the antiferromagnetic state, followed by a transition to a spin glass state at lower temperatures. The unusual change of the magnetic properties with magnetic substitution at the Mn positions is attributed to the peculiar antiferromagnetic structure of braunite, which has been resolved recently. Received: 19 April 2001 / Accepted: 6 September 2001     

浅水浮式生产储油系统(FPSO)二阶定常力数值仿真研究

应用三维线性势流理论和Ir J A Pinkster的近场分析方法,对超大型浮式生产储油系统(32万吨FPSO)的二阶波浪定常力进行了数值仿真分析,研究浅水情况下,不同水深对FPSO受到二阶波浪定常力的影响,对浅水油田中FPSO的设计应用有一定的实用意义。     

Coherency matrix-based proper orthogonal decomposition with application to wind field simulation

Proper Orthogonal Decomposition （POD） provides a powerful modal transformation tool for stochastic dynamics. In this paper, coherency matrix-based proper orthogonal decomposition （CPOD） is presented as an innovative form of the POD based on cross power spectral density matrices. By introducing a discretizing scheme, the CPOD-based spectral representation method is obtained for use in stochastic simulation. Moreover, some criteria are proposed that allow the truncation order of CPOD to be conveniently determined. A numerical example to illustrate the application of the proposed method for the simulation of a wind velocity field is provided.     

频率域线源大地电磁法有限元正演模拟

本文介绍了频率域线源大地电磁法有限元正演模拟的研究结果. 在外边界上统一应用适合于人工源的一阶吸收边界条件来形成边值问题,可减小基于平面波假设造成的人为截断边界的影响. 程序编辑中设计了两个二维数组分别存储总体系数矩阵的非零元素和在总体结点编号中的位置,使内存占用量减少,且物理意义明确,方便用高斯-赛德尔等迭代法解有限元方程时调用. 采用视δ函数模拟线源,提高了解方程组的稳定性. 最后通过对1个简单模型和1个复杂模型的模拟,证明所用的方法对异常体能够有明显的反映,说明了该方法的可靠性和有效性.     

自驾天气服务系统的设计与实现

自驾、客运和货运活动中,行驶路段天气状况已成为关系安全行驶的关键要素,使得个性化、精细化的自驾天气信息服务作为专业化气象服务的新需求越发强烈。为满足该需求,提出一套自驾天气服务系统模型。该系统模型以计算机Google Maps地图方式定制路线,手机客户端接收服务短信为目标完成设计。该设计以"数据→信息→知识→产品"的思路处理气象数据,获得的客观分析格点场气象服务信息作为气象服务基础;路线处理以Google Map API解析用户定制路线的JSON为基础,采用PrimeFaces的Decoder方法和分布函数过滤得到途经点路线的地理坐标集;最后对定制用户以短信方式提供途经点的气象信息服务。基于本模型开发的自驾天气服务系统已经投入试运行,开拓了新的短信气象服务业务方式。     

应用非线性高阶谐波衰减和尾波干涉监测高温作用后水泥制品的损伤演化

非线性高阶谐波和尾波波速变化均能够反映水泥材料内部微结构的应力变化。利用高阶谐波和尾波干涉实验测量系统,对引入高温作用后的3类不同粒径共6块水泥试样进行单轴加载的损伤演化实验,并与无高温作用的完整试样的实验结果进行对比。结果表明,从初始状态到25%抗压强度的过程中,高温作用后的试样的谐波幅值和尾波波速变化出现明显增强的现象（谐波幅值最大增幅约20%）,而无高温作用的完整试样的谐波幅值和尾波波速变化较为平稳（谐波幅值最大增幅约5%）;在达到65%抗压强度的过程中,高温作用后的试样的谐波幅值和尾波波速变化急剧增大（谐波幅值最大增幅约100%）,且粒径较大的试样的增幅高于粒径较小的试样,而无高温作用的完整试样的谐波幅值和尾波波速变化的增幅较小（谐波幅值最大增幅约10%）;当抗压强度超过75%以后,高温作用后的试样的谐波幅值和尾波波速变化急剧衰减（谐波幅值最大衰减幅度约140%）,而无高温作用的完整试样的谐波幅值和尾波波速的最大衰减幅值在40%以内。基于以上观测结果对高温作用后水泥制品损伤演化的物理机制以及这两类监测方法的适用性进行了讨论。     

A frequency‐dependent and intensity‐dependent macroelement for reduced order seismic analysis of soil‐structure interacting systems

The computational demand of the soil‐structure interaction analysis for the design and assessment of structures, as well as for the evaluation of their life‐cycle cost and risk exposure, has led the civil engineering community to the development of a variety of methods toward the model order reduction of the coupled soil‐structure dynamic system in earthquake regions. Different approaches have been proposed in the past as computationally efficient alternatives to the conventional finite element model simulation of the complete soil‐structure domain, such as the nonlinear lumped spring, the macroelement method, and the substructure partition method. Yet no approach was capable of capturing simultaneously the frequency‐dependent dynamic properties along with the nonlinear behavior of the condensed segment of the overall soil‐structure system under strong earthquake ground motion, thus generating an imbalance between the modeling refinement achieved for the soil and the structure. To this end, a dual frequency‐dependent and intensity‐dependent expansion of the lumped parameter modeling method is proposed in the current paper, materialized through a multiobjective algorithm, capable of closely approximating the behavior of the nonlinear dynamic system of the condensed segment. This is essentially the extension of an established methodology, also developed by the authors, in the inelastic domain. The efficiency of the proposed methodology is validated for the case of a bridge foundation system, wherein the seismic response is comparatively assessed for both the proposed method and the detailed finite element model. The above expansion is deemed a computationally efficient and reliable method for simultaneously considering the frequency and amplitude dependence of soil‐foundation systems in the framework of nonlinear seismic analysis of soil‐structure interaction systems.     

基于多位点分子标记和线粒体基因组学中国蚌类(蚌目:蚌超科)物种分类与系统进化研究

中国是东亚蚌类（蚌目：蚌超科）物种分布中心,共记录有26属.然而,在世界蚌目框架下,中国仍缺乏一个完整科学的蚌类分类系统.本研究基于多位点分子标记（COI、16S、28S）和线粒体基因组学重构聚焦于蚌超科的蚌目系统发育关系,ML、BI和BEAST系统发育结果均支持蚌科5亚科分类系统,即（（（Ambleminae+Gonideinae）+Rectidentinae）+Unioninae）+Parreysiinae;珍珠蚌科2亚科分类系统,即（Gibbosulinae+Margaritiferinae）;中国蚌类隶属蚌科4亚科（Gonideinae,Rectidentinae,Unioninae,Parreysiinae）13族和珍珠蚌科两亚科（Gibbosulinae,Margaritiferinae）.基于化石标定的分子钟显示：蚌科物种分化时间为中三叠世（median=232.07 Ma）,其中雕刻蚌亚科（Parreysiinae）起源和物种分化时间早于其他亚科;矩形蚌亚科（Rectidentinae）物种分化时间最晚,为晚白垩世（median=94.72 Ma）;小方蚌亚科（Ambleminae）和隆脊蚌亚科（Gonideinae）最近共同祖先分化于晚侏罗纪世（median=144.69 Ma）,珍珠蚌科起源于晚石炭世（median=312.61 Ma）,物种分化于晚白垩世（median=91.59 Ma）,中国蚌科现生物种最早起源时间可追溯到白垩纪（中国尖嵴蚌（Acuticosta chinensis）,median=114.36 Ma）.蚌超科线粒体基因重排分析显示：蚌超科线粒体基因组有4种基因排列方式（GO）,珍珠蚌科独享一种（GO1）;蚌科中Unioninae和Ambleminae共享一种（GO2）;Gonideinae有2种基因排列方式（GO3和GO4）,其中室蚌（Chamberlainia hainesiana）独享一种（GO4）,其余物种共享一种（GO3）.以往作为高阶元分类的贝壳形态、钩介幼虫形态以及育儿囊类型,并不能作为蚌科属及以上阶元分类依据.本研究重构了世界蚌目聚焦于蚌超科的系统发育关系和进化历史,建立了中国蚌类分类系统,为今后该类群区系多样性研究及资源保护提供了分类依据.