火山Mogi模型形变反演的虚拟观测法及方差分量估计

针对Mogi模型垂直位移与水平位移联合反演中的病态问题,改进火山形变总体最小二乘(Total Least Squares,TLS)联合反演的虚拟观测法,并使用方差分量估计(Variance Components Estimation,VCE)方法确定病态问题的正则化参数.将附有先验信息的参数作为观测方程,与垂直位移和水平位移的观测方程联合解算,推导了三类观测方程联合反演的求解公式及基于总体最小二乘方差分量估计确定正则化参数的表达式,给出了算法的迭代流程.通过算例实验,研究了总体最小二乘联合反演的虚拟观测法在火山Mogi模型形变反演中的应用;算例结果表明,三类数据的联合平差及方差分量估计方法可以确定权比因子并得到修正后的压力源参数,具有一定的实际参考价值.     

使用量化器件获得高精度测量方法的几点讨论

本文从列阵器件测量精度的估计公式出发，推导了用低精度Ａ／Ｄ变换器件获得高精度测量结果的一般性证明，还讨论了这种方法的若干可能应用。     

Analysis of the Variability of a Two-Dimensional Finite Strain Estimate

Finite strain estimation is a widely used technique for the study of rock deformation in structural geology. One particular algorithm proposed by Shimamoto and Ikeda uses the ‘average shape matrix’ of deformed markers. This paper provides a detailed error analysis for resulting strain estimates in two dimensions. When the number of markers exceeds 100, estimators of components of the strain tensor are shown to have an approximately Gaussian distribution with variances that increase with their mean. Equal variance estimators are obtained by applying a log transform for the elongation and an arcsin transformation for the orientation estimates. Confidence interval formulae for strain tensor components are proposed. Lithology specific constants arising in these formulae are estimated from undeformed samples. The results are validated by application to simulated data as well as observational data from thin sections of sandstone sampled from SE Ireland.     

赫尔默特方差分量估计在混合水准网平差中的应用

测量中有些时候会碰到定权不统一的问题,导致了平差后的结果不理想.本文主要讨论的是通过赫尔默特方差估计的方法消除由于定权的不合理而产生的精度超限问题.通过实例进行分析表明,利用赫尔默特方差分量估计在进行迭代定权非常实用,大大提高了其精度.     

The spectral composition of fluxes and variances over land and sea out to the mesoscale

We discuss the accuracy requirements for measuring mesoscale (roughly horizontal scales > 10 km or 5 to 10 times the planetary boundary-layer (PBL) depth) fluxes in the convective PBL, and the ability of current research aircraft to achieve this accuracy. We conclude that aircraft equipped with inertial nagivation systems capable of < 3 km hr⁻¹ navigational accuracy are able to resolve mesoscale fluctuations in velocity, and thus variances and fluxes on the mesoscale. We then discuss measurements of velocity and scalar spectra, and cospectra of vertical velocity with horizontal velocity components and scalars, obtained from long flight legs with the National Center for Atmospheric Research Electra aircraft over the boreal forest of Canada in summer during the BOreal Ecosystem-Atmosphere Study (BOREAS), over the tropical Pacific Ocean from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE), and over the East China Sea during wintertime cold-air outbreaks from the Air Mass Transformation Experiment (AMTEX). Each of these studies has somewhat different forcings and boundary conditions, so we can compare their consequences on the spectra and cospectra. On average, we found no significant scalar or momentum fluxes for horizontal scales > 10 km. We also develop a simple model based on observed thermal structure to explain the phase angle between vertical velocity and the along-wind horizontal velocity as a function of height, which shows good agreement with the observed phase angle in AMTEX. The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Spatially non-stationary relationships between urban residential land price and impact factors in Wuhan city,China

Land price plays an important role in guiding land resource allocation for urban planning and development, particularly in big cities of fast developing countries where infrastructures and populations change frequently. Therefore, detecting spatially implicit information in the spatial pattern of relationships between land price and related impact factors is critical. Geographically weighted regression (GWR) analysis was conducted in this study for the purpose in Wuhan, China, by using a 10-year panel data set of residential land price. Based on twelve factors in three aspects (land attributes, location factors and neighborhood attributes), an evaluation index system of resident land price was established. The spatial distributions of estimated coefficients and pseudo t-values of three major explanatory variables (floor area ratio, distance to nearest center business district (CBD) and distance to nearest lake), obtained from GWR analysis, indicated that their relationships of the impact factors with land price are spatially non-stationary. The positive impact of floor area ratio on land price is more significant in highly developed areas than in less developed areas. Conversely, the negative impact of distance to nearest CBD on land price is larger in highly developed areas than in less developed areas. Moreover, wealthier dwellers may be willing to pay a higher price for a good lake view (especially views of small lakes), but infrastructure barriers (near some large lakes) cause negative effect. The outputs of this study, which provide detailed information on the relationships between land price and impact factors in local areas, are promising for urban planners to scientifically evaluate land price and make area-specific strategies.     

印度洋-太平洋海温长期变化的周期性及其年代际变化

运用小波分析方法对近百年来印度洋－太平洋海温的周期变化特征进行了详细讨论,并且结合以前的工作,运用方差分析的方法对近半个世纪以来各周期振荡水平分布的年代际变化进行了综合分析。研究表明：近百年中,赤道东太平洋海温的长期变化不仅具有准两年（ＱＢＯ）和３－７年（ＬＦＯ）的年际振荡,而且具有１０－１２年、１８－２０年和３０－４０年的年代际振荡。各振荡分量的振幅和周期具有显著的年代际变化特征。近半个世纪各振     

一种消除不规则地物影响的规则地物边缘检测算子

对传统的边缘检测算子来说，虽然本身或在使用方法上都有一定的抑制噪声能力，但是效果并不明显，所以本文提出一种改进的方向方差算子，能够在检测“规则”地物边缘的同时，有效的抑制了“不规则”地物的影响。实验中，与传统的边缘检测算子进行了比较，结果证明本算法是有效的。     

Generalized maximum-likelihood estimation of variance components with inverted gamma prior

A new method for the estimation of variance components is presented. The proposed method combines the concept of maximum-likelihood estimation with the Bayesian approach and facilitates computationally efficient introduction of prior information into the estimation process. Received: 22 April 1998 / Accepted: 19 April 1999