青藏高原地表长波辐射参数化及其气候计算

根据１９８２年８月至１９８３年７月青藏高原辐射平衡资料，详细讨论了该地区活动面温度与地表温度的关系，提出了两种计算地表长波辐射的参数化方法Ｕ＝ｋδσ（Ｔ０＋２７３）＾４和Ｕ＝δσ［（Ｔ０＋２７３）＋ΔＴ］＾４。经反演检验，两式的拟合精度相同（均为３．６％），并适用于作瞬时和平均通量密度计算，文中还就ｋ、ΔＴ的日、年变化作了分析，计算并讨论了青藏高原地表长波辐射的气候特征。     

EOF和CCA方法在台风路径预报试验中的比较

利用气候持续性因子，并分别考虑了５００ｈＰａ高度场的ＥＯＦ因子和ＣＣＡ因子，分别建立了基于ＥＯＦ因子和基于ＣＣＡ因子的南海台风２４－１２０小时路径预报模式。经过非独立样本和独立样本的预报检验，比较。将两种方法运用于５００ｈＰａ高度场的分析表明，ＣＣＡ方法得出的典型变量权重系数分布虽不能象ＥＯＦ方法的特征向量一样表示出明显的而且平滑的空间场形式，但ＣＣＡ方法浓缩了更多的与台风路径整体相关性最好的原变     

Dynamic characterization of a long span bridge: A finite element based approach

Aging bridges coupled with increasing traffic loads are producing a severe toll on the nation's infrastructure. This has made it necessary to take a closer look at the health of existing bridges and develop automated damage identification methods if possible. Recent works in the field of structural dynamics have shown that damage detection techniques utilizing parameters like mode shapes, modal frequencies and damping ratios can be used to identify damage in structural systems. It is, however, important to be able to establish a baseline model for the structure first, and then a model updating technique can be utilized to evaluate the condition of the structure from time to time. It is with this goal in mind that the authors have decided to establish the process for obtaining a baseline model for a long span bridge. Based on the actual design drawings of a bridge, finite element (FE) models of the bridge in question are developed using SDRC-IDEAS. Three models of the bridge are simulated using Normal Mode Dynamics solver in SDRC-IDEAS to obtain the modal parameters of interest, in this case the modal frequencies and the mode shapes. A modal assurance criteria (MAC) is utilized to compare the different simulated mode shapes and, finally, the modal frequencies that have been obtained from the FE analysis are compared to frequencies that have been obtained from some preliminary field tests.     

高速大动态范围数据采集器

本文介绍了一种新的数据采集模块，并对其硬软件的构成及应用作简要说明。     

763面波震级和大震速报

大量的观测资料表明我国大震速报台网与世界台网震级存在较大的偏差，而７６３面波震级与世界台网比较一致的事实，提出了将７６３面波震级用于大震速报的建议及其可行性。     

超远距离HF传播预测值与实测值的比较

本文主要对超远距离HF传播信号场强测量值与山CCIR第894—2号报告书方法所做的预测值进行了比较,其平均偏差为-1.7dB,标准均方根偏差为13.5dB。最后分析了偏差的原因并对预测方法进行了评估,指出预测值偏低和对极点聚焦公式应当修改,这将大大提高第894—2号报告方法的预测精度。     

Homogeneous Indian Monsoon rainfall: Variability and prediction

The Indian summer monsoon rainfall is known to have considerable spatial variability, which imposes some limitations on the all-India mean widely used at present. To prepare a spatially coherent monsoon rainfall series for the largest possible area, fourteen subdivisions covering the northwestern and central parts of India (about 55% of the total area of the country), having similar rainfall characteristics and associations with regional/global circulation parameters are merged and their area-weighted means computed, to form monthly and seasonal Homogeneous Indian Monsoon (HIM) rainfall series for the period 1871–1990. This paper includes a listing of monthly and seasonal rainfall of HIM region. HIM rainfall series has been statistically analysed to understand its characteristics, variability and teleconnections for long-range prediction. HIM rainfall series isfound to be homogeneous, Gaussian distributed and free from persistence. The mean (R) rainfall is 757 mm (87% of annual) and standard deviation (S) 119 mm, with a Coefficient of Variation (CV) of 16%. There were 21 dry (K, -<R S) and 19 wet (R _i R + S) years during 1871–1990. There were clusters of frequent negative departures during 1899–1920 and 1965–1987 and positive departures during 1942–1961. The recent three decades show very high rainfall variability with 10 dry and 6 wet years. The decadal averages were alternatively positive and negative for three consecutive decades, viz., 1871–1900 (positive); 1901–1930 (negative); 1931–1960 (positive) and 1961–1990 (negative) respectively. Significant QBO and autocorrelation at 14th lag have been found in HIM rainfall series. To delineate the changes in the climatic regime of the Indian summer monsoon, sliding correlation coefficients (CCs) between HIM rainfall series and (i) Bombay msl pressure, (ii) Darwin msl pressure and (iii) Northern Hemisphere surface air temperature over the period 1871–1990 have been examined. The 31-year sliding CCs showed the systematic turning points of positive and negative CCs around the years, 1900 and 1940. In the light of other corroborative evidences, these turning points seem to delineate ‘meridional’ monsoon regime during 1871–1900 and 1940–1990 and ‘zonal’ monsoon regime during 1901–1940. The monsoon signal is particularly dominant in many regional and global circulation parameters, during 1951–1990. Using the teleconnections ofHIM series with 12 regional/global circulation parameters during the recent 36-year period 1951–86 regression models have been developed for long-range prediction. In the regression equations 3 to 4 parameters were entered, explaining upto 80% of the variance, depending upon the data period. The parameters that prominently enter the multiple regression equations are (i) Bombay msl pressure, (ii) April 500 mb Ridge at 75°E, (iii) NH temperature, (iv) Nouvelle minus Agalega msl pressure and (v) South American msl pressure. Eleven circulation parameters for the period 1951–80 were subjected to Principal Component Analysis (PCA) and the PC’s were used in the regression model to estimate HIM rainfall. The multiple regression with three PCs explain 72% of variance in HIM rainfall.     

Another look at anisotropy in geostatistics

A thorough geostatistical data analysis includes a careful study of how the data's second-order variation, as characterized by the semivariogram, depends on the relative orientation of data locations. If the semivariogram depends on only the (Euclidean) distance between locations, then the semivariogram is isotropic; otherwise, it is anisotropic. In this article, I take another look at the modeling of anisotropy in geostatistics. A new, more specific classification of types of anisotropy is proposed. More importantly, some heretofore inadequately understood implications of the dependence of various semivariogram attributes on direction are discussed, and the wisdom of some current practices for modeling the direction-dependence of these attributes is questioned.     

乌鲁木齐地区地磁静日场Sq的变化特征

根据乌鲁木齐地磁台所编的1989年《地磁观测报告》,采用地磁静日场的水平分量(H)和垂直分量(Z)资料,选用其特征量——日变幅和相位,对乌鲁木齐地区地磁静日场S_q的变化特征进行初步统计分析表明,该工作对于进一步认识和研究乌鲁木齐地区地磁静日场的变化规律,为利用地磁预报地震提供背景值资料具有一定意义。     

Conditioned ranges for independent symmetric three valued inflows

The paper considers, as inputs to a storage system, independent random variablesX ₁,X ₂,... which have a symmetric three-valued distribution. Expressions are obtained for the conditional expected values of (i) the adjusted range ofX ₁,...X _n, conditioned on the eventX ₁+...+X _n=0; (ii) the Hurst range ofX ₁,...,X _n , conditioned on essentially the same event. Numerical comparisons of these two conditioned ranges show that they are close in value unless the inputs have high kurtosis.