基于热点参考系的板块绝对运动模型

本文在最新一代板块相对运动模型(MORVEL模型)的基础上,通过最小二乘反演观测热点方向数据建立板块绝对运动模型.经过对前人用于约束板块绝对运动模型的所有热点数据与MORVEL模型的一致性作系统的统计学检验,发现存在离群数据.相应地,提出两种系统剔除离群数据的新方法:逐一剔除法和全局搜索法.结合对总残差的卡方检验和对残差频率分布的正态检验,逐步筛选最优模型,最终得到一个基于热点参考系的板块绝对运动新模型(T87模型).该模型能够合理拟合全球分布的87个热点方向数据,而模型预测的板块绝对运动速率比观测热点火山的迁移速率系统偏小,最大偏差达到4 cm·a~(-1).这样的偏差可由观测热点速率的系统误差或地幔返回流造成的热点间运动解释.不论是哪种解释成立,本文结果表明热点方向数据能够独立、有效地定义全球热点参考系.这样定义的热点参考系可方便地应用于板块绝对运动、地幔对流及真极移的研究.     

含有控制时滞系统的输出反馈扰动抑制

研究在持续外界扰动作用下,具有控制时滞线性系统的动态输出反馈扰动抑制问题。首先利用模型转换将控制时滞系统转化为形式上无时滞的系统,通过求解Riccati方程和Sylvester方程,推导出前馈—反馈最优扰动抑制控制律。然后构造能同时预估状态和扰动的降维观测器,不仅解决前馈控制和状态反馈的物理不可实现问题,而且得到了近似于最优扰动抑制控制律的动态输出反馈扰动抑制控制器。仿真实例证明此控制律的有效性。     

密云综合孔径射电望远镜的干扰抑制(英文)

MSRT(密云综合孔径望远镜)从1985年起投入工作。在多年的观测中经常发现来自外部的强大干扰,严重影响着成图的质量。为了抑制观测过程中出现的各类干扰,我们发展了两种软件技术——剔除法和频域滤波法。滤波法的优点在于保留了全部观测信息,适合于长时间强干扰的情形。剔除法对脉冲形的干扰更为敏感有效。这两种技术的配合使用能有效、灵活地抑制各种不同干扰的影响。     

利用Matlab GUI实现磁测数据畸变点的交互式剔除

进行高精度磁测会受到很多地表干扰,造成采集数据畸变,因此必须在各种处理方法运用之前剔除掉。利用Matlab GUI的可视化、绘图及鼠标事件功能,实现了交互式地剔除地表磁测数据中畸变点的方法。实践表明,这种方法不仅提高了畸变点的剔除效率,还可以最大程度地保留正常数据点的信息。     

Ocean mixing with lead-dependent subgrid scale brine rejection parameterization in a climate model

Sea ice thickness is highly spatially variable and can cause uneven ocean heat and salt flux on subgrid scales in climate models.Previous studies have demonstrated improvements in ocean mixing simulation using parameterization schemes that distribute brine rejection directly in the upper ocean mixed layer.In this study,idealized ocean model experiments were conducted to examine modeled ocean mixing errors as a function of the lead fraction in a climate model grid.When the lead is resolved by the grid,the added salt at the sea surface will sink to the base of the mixed layer and then spread horizontally.When averaged at a climate-model grid size,this vertical distribution of added salt is lead-fraction dependent.When the lead is unresolved,the model errors were systematic leading to greater surface salinity and deeper mixed-layer depth(MLD).An empirical function was developed to revise the added-salt-related parameter n from being fixed to lead-fraction dependent.Application of this new scheme in a climate model showed significant improvement in modeled wintertime salinity and MLD as compared to series of CTD data sets in 1997/1998 and 2006/2007.The results showed the most evident improvement in modeled MLD in the Arctic Basin,similar to that using a fixed n=5,as recommended by the previous Arctic regional model study,in which the parameter n obtained is close to 5 due to the small lead fraction in the Arctic Basin in winter.     

组合桩在唐山沿海地区的试验应用

唐山沿海地区由于自然历史原因造成土体结构与内陆地区相差甚远,土体结构多层,且上部以软弱粘性土、砂类土为主,使得单一桩型成本较高、效率低、施工难度大且易造成环境污染。针对这些问题并结合本地区地层,设计试验了一套粉喷桩和预应力混凝土管桩相结合的柔刚组合桩施工方法,降低了施工难度、提高了效率、降低了成本,实现桩基施工无泥浆排放的节能环保示范,为类似地区地基基础工程施工提供了借鉴和参考。     

统计检验中两类错误与拒绝域的确定

本文通过实例分析,说明对于给定的统计检验模型应根据实际问题的使用与经济价值区别不同情况,合理地控制犯第一类错误与第二类错误的概率以及样本容量,从而去确定最优拒绝域。而不应笼统地采用现行的传统做法,即通常限定第一类错误的概率(显著水平)的前提下,去寻求最优拒绝域。     

SIPVADE: A New Computer Programme with Seventeen Statistical Tests for Outlier Detection in Evaluation of International Geochemical Reference Materials and its Application to Whin Sill Dolerite WS-E from England and Soil-5 from Peru

A new computer programme was written in programming language TURBOC, which enables us to apply a procedure involving seventeen statistical tests (a total of sixty five single or multiple outlier versions of these tests) for outlier detection in univariate sample at a high confidence level of 99% (significance level α= 0.01). The outlying observations should be evaluated first for technical reasons and then rejected manually from the data base until no more outliers are detected and the final statistical parameters are computed from the remaining data. This programme has been used successfully to process two reference material data bases: WS-E from England and Soil-5 from Peru. The final mean values for WS-E are more reliable (characterized by smaller standard deviations and narrower confidence limits) than those obtained earlier using a different statistical approach. The application of a large number of statistical tests to Soil-5 also resulted in smaller standard deviation values for most elements than the method involving a limited number of such tests. For WS-E, some laboratories seem to have produced multiple data that were detected as statistical outliers. A close analysis of the distribution of outliers as a function of laboratory, country and analytical method leads to a technical justification for these outlying observations, probably in terms of inadequate QA/QC practices. Use of geochemical criteria indicates that the new mean values in WS-E might be closer to the "true" concentrations. This procedure of outlier detection and elimination is therefore recommended in the study of the existing RM.     

Laboratory experiment and digital simulation of multiple fill-cut terrace formation

The formation mechanism of multiple erosional terraces which develop in the dissection process of sedimentary valley fills was investigated by laboratory experiments and computer simulations. Sequences of unpaired terraces were produced on experimental fan-like deposits under conditions of constant water discharge, no base-level change, and no sediment supply. The terraces developed as a result of the repetition of lateral shifting and stillstand of the stream channel at each cross-section during continuous downcutting. This mode of channel migration was caused by meander growth during which amplitude and wavelength increased with time. The terrace formation process was well-reproduced by computer simulations using a meander model having a similar wave mode.