Attenuation characteristics of peak ground acceleration from fault trace of the 1999 Kocaeli (Turkey) earthquake and comparison of spectral acceleration with seismic design code

The 17 August 1999 Kocaeli earthquake in Turkey produced a majorsurface rupture. We traced this surface rupture from Gölcük toDüzce and located it accurately by using GPS. The closest distancefrom the surface rupture to the strong motion observation sites weredetermined. Then the attenuation characteristics of the observed peakground acceleration were compared with the attenuation relation given byFukushima and Tanaka (1992), which is suitable for the near-fault zone inJapan and gives results that closely match data recorded during the 1995Hyogo-ken Nanbu earthquake in Japan. Although this attenuation relationwas developed for Japan, we found that it agreed well with the KOCAELIearthquake. Furthermore, the observed spectral acceleration of 5%damping was compared with the building design code of Turkey and theobserved level was lower than the code.     

Gravity interpretation of nonoutcropping sedimentary basins in which the density contrast decreases parabolically with depth

The decrease in density contrast of sedimentary rocks with depth in many sedimentary basins can be approximated by a parabolic density function. Analytical gravity expression of an outcropping two-dimensional vertical step along which the density contrast decreases parabolically with depth is derived in the space domain. A modification ofBott's (1960) method of gravity interpretation is proposed by considering two outcropping vertical steps on either side of the first and last observation points in addition toN outcropping vertical prisms in order to interpret the gravity anomalies of nonoutcropping basins. The thicknesses of the two outcropping vertical steps are made equal to the thicknesses of the two outcropping vertical prisms placed below the first and last observation points. The initial depth estimates of the sedimentary basin are calculated by the infinite slab formula ofVisweswara Rao et al. (1993). The gravity effects of theN outcropping prisms and the two outcropping vertical steps are calculated at each anomaly point and the depth to the floor of the basin are adjusted based on the differences between the observed and calculated anomalies. A gravity anomaly profile of Los Angeles basin, California is interpreted.     

改进的Berlekamp算法在数据收集平台处理中的应用

该文采用改进后的Berlekamp迭代算法，应用于气象卫星数据收集平台BCH地址码的译码、纠错问题。针对（31、21）BCH码，该算法在随机纠正2位错码时，具备了迭代次数少、计算速度快的特点。经过计算证明，此方法用于数据收集平台的BCH码的译码、纠错是可行的。     

基于二叉树的栅格数据快速编码及其实现

在对常规编码方法存在的不足进行分析的基础上，提出了在一次遍历栅格数据过程中生成线性二叉树的快速动态编码以及地程编码方法，该方法用堆栈的思想代替传统的线性表，以十进制orton码为顺序提取栅格单元数据并介入栈，以压栈的方式完成栅格单元或结点向上层的递归合并。当对整个栅格数据遍历一次后，栈中剩下的记录便是所需的线性二叉树编码结果。通过对算法的分析表明，该方法具有明显的优点和重要意义。     

Static deformation of an orthotropic multilayered elastic half-space by two-dimensional surface loads

The transfer matrix approach is used to solve the problem of static deformation of an orthotropic multilayered elastic half-space by two-dimensional surface loads. The general problem is decoupled into two independent problems. The antiplane strain problem and the plane strain problem are considered in detail. Integral expressions for displacements and stresses at any point of the medium due to a normal line load and a shear line load, acting parallel to a symmetry axis, are obtained. In the case of a uniform half-space, closed form analytic expressions for displacements and stresses are derived. The procedure developed is quite easy and convenient for numerical computations.     

DCS与MBMIS注记信息的转换

本文介绍了由“数字地籍测量系统(DCS)”注记信息形成“军队基建营房图形管理信息系统(MBMIS)”注记图元的过程以及西文字符的ASCII码与中文方式下相应字符的机内码转换算法。     

图式符号的编码及其它

本文就大比例尺地形图图式符号提出了一个按层、类、目安排的3位数字编码,不仅覆盖了全部图式符号,而且还包括图外整饰、图面注记、甚至地籍测量符号,有利于数字地形测量和数字地藉测量的规范化和标准化。另外,还附带提出了某些地形符号的改进意见,以期适应当前计算机绘图的需要。     

GRIB码的二级压缩

ＧＲＩＢ码是目前世界气象组织建议使用的二进制比特流压缩代码，适用于表示数值天气预报产品的格点场数据，该文在ＧＲＩＢ码一级压缩原理等内容简介的基础上，着重讨论了ＧＲＩＢ码二级压缩的概念，原理和方法。     

全球地震地理分区

文中描述了国际地震地理分区的现状（Ⅰ、Ⅱ、Ⅲ级）。介绍了中国大陆地区的Ⅲ级地震地理分区。提出了中国地震地理分区的建议。     

Magnetic anomalies of two-dimensional bodies and algorithms for magnetic inversion of dykes and basement topographies

Generalized equations for the anomalies in any component of the earth’s magnetic field due to two-dimensional bodies of arbitrary magnetization are derived in terms of a new parameter, called the direction of measurement. Schemes for inverting the magnetic anomalies of arbitrarily magnetized dykes and basement topographies are then developed and the relevant computer software is presented. In both the schemes, the initial values of the parameters are calculated by the computer, so that the input merely consists of the anomalies and their distances. The differences in the observed and calculated anomalies are solved iteratively for the errors in initial values of the parameters.