矩谱法求磁性体质心的若干问题

B K Bhattachryya(1975)推导的求磁性体质心的矩谱公式理论严谨,计算速度快,并且有不需要预先知道磁性体磁化率的特点。在该公式的基础上,本文对求质心的各种影响因素作了细致讨论,推导出了提高求解质心精度的改正公式。     

对数功率谱法计算磁性体顶底深的若干问题

对数功率谱法是计算磁性体顶深、底深的常用反演方法之一。该方法简单、计算速度快,并且不需要预先知道磁性体的磁化率。本文对该方法在实际资料处理时遇到的一些问题做了进一步的研究。通过对计算磁性体顶深、底深的误差分析,证明计算顶深的精度较高。对于非均匀磁化模型,作者推导出其谱公式,这与均匀磁化模型的谱公式近似相等,从而证明对数功率谱法计算磁性体顶、底深度不受非均匀磁化影响。三度磁性体的二度近似计算也是完全可靠的。 最后,计算了山西省太原盆地磁性体顶深,其结果与已有的地质、地球物理资料相符合。     

五维波动问题的一种解法

介绍解五维波动问题的微分算子级数法,首先引进数性算子概念及微分算子级数法;其次,推导出了求解公式;最后通过求解公式求解了一些五维波动方程的例题,得出任何维数(n≥5)的波动方程柯西问题都可以用微分算子级数法求其解。     

五维波动问题的一种解法

介绍解五维波动问题的微分算子级数法，首先引进数性算子概念及微分算子级数法；其次．推导出了求解公式；最后通过求解公式求解了一些五维波动方程的例题，得出任何维数（n≥5）的波动方程柯西问题都可以用微分算子级数法求其解。     

用球函数展开法求解轴对称稳恒磁场

本文用球函数展开法推导出计算轴对称三维稳恒磁场矢势的公式，应用该公式既能计算电流分布区域外部的磁场，又能计算电流分布区域内部的磁场。最后给出了应用文中公式求解轴对称稳恒磁场的具体例子。     

基于Neuman井流理论确定玄武岩潜水含水层渗透系数的应用——以吉林靖宇煤矿为例

全面分析研究区玄武岩潜水含水层水文地质条件的基础上,对稳定流和非稳定理论确定潜水含水层渗透系数的优缺点进行了对比,认为非稳定井流公式确定玄武岩潜水含水层渗透系数是合理的。Aquifer Test软件基于Neuman井流理论配线法求参原理,运用计算机完成了自动求参,避免了人工配线的不足。该文根据吉林靖宇煤矿研究区玄武岩潜水含水层非稳定流抽水试验,分别用Aquifer Test软件和稳定井流公式进行了求参,并对比分析得出:玄武岩含水层弹性释水作用影响时间较长,利用Neuman潜水井流公式求参可靠,且更逼近现实;用Aquifer Test软件实现了自动求参,具有操作简单规范、可比性好的优点。     

磁法θ图方法在圈定磁性体边界中的应用

近几年提出的导数处理方法θ图法利用极大值圈定磁性体边界,其算法主要步骤为计算垂向一阶导数与总水平导数的比值。通过分析二维半情况下不同磁性体模型的θ图,总结了θ图极值与直立磁性体边界、倾斜磁性体边界、岩体及矽卡岩带边界的对应性规律。该方法对重力圈定断裂构造及地质界线也有借鉴意义。     

二维板状体反演计算产状参数的一种方法

计算磁性矿休(脉)的产状参数,是磁异常解释推断的重要内容。本文主要讨论了利用磁异常复梯度振幅曲线A(x)和相位曲线Φ(x),某些特征点坐标及振幅值计算产状参数的方法—复梯度法。详细地推导了反演计算公式。     

关于电法异常正演计算的类磁法公式

本文根据金属矿地球物理勘探中磁法和电法工作的特点,分析归纳了椭球类(包括球、圆柱、椭球柱等形体)矿体磁异常公式,引出了用类磁参数表示的矿体视电阻率异常、时间域和频率城激电异常、低频电磁法异常公式。从而较好地建立了数学模型,在一定的条件下,简化了金属矿电法异常正演计算,加深了电法异常性质和特点的认识和研究,并对文献[1]在椭球体磁场公式和激发极化异常的类磁法公式中的一些笔误作一商榷。     

一种由铣刀刃形求螺旋槽形状方法的探讨

根据无瞬心包络原理,用向量法推导一种由已知铣刀刃形求螺旋槽形状的简便计算公式和方法.     

Study on slope reliability method Response Surface Method based on Morgenstern-Price Method

The combination of Morgenstern-Price Method （MPM） with Response Surface Method （RSM） improves the eonventional RSM by replacing Finite-Element Method （FEM） with MPM, which is a type of reliability analysis method-RSM based on MPM, and makes the computing process simpler. The stability of the slope was re-evaluated by use of Monte Carlo method （MCM） and the result contrasted with the fore is the conclusion. The reliability analysis of the artificial slope in Donggang Power Station was carried on, and obtained the reliable charaeteristics, which provided basis for the project.     

Study on slope reliability method Response Surface Method based on Morgenstern-Pr ice Method

The combination of Morgenstern-Price Method (MPM) with Response Surface Method (RSM) improves the conventional RSM by replacing Finite-Element Method ( FEM) with MPM, which is a type of reliability analysis method-RSM based on MPM, and makes the computing process simpler. The stability of the slope was reevaluated by use of Monte Carlo method (MCM) and the result contrasted with the fore is the conclusion. The reliability analysis of the artificial slope in Donggang Power Station was carried on, and obtained the reliable characteristics, which provided basis for the project.     

A preliminary study on the relation between the thermal and geometric surface centroids of the Western Pacific Warm Pool

Numerous published results have showr the importance of the Wcstern Pacific Warm Pool （WPWP）surface centroid movement in ENSO-（EI Nino/Southcrn Oscillation）rclated studies .Howcver,some rccent research conclusions make it necessary to clarify the differenccs of the currently exicing two types of WPWP surface centroid：the geometric centroid and the thermal （heat）centrold.This study analyzes the physical backgrounds of the two typcs of centroid and points out their differenccs.which suggest that different types of ccntroid may scrve different study purposes.This study also shows that the ‘geometric center’of WPWP.actually a close approximation to the mass ccntroid,is more related to the Nino-3 region sca surfacc temperaturc（SST）ancmaly and can also be regarded as an important indicator of ENSO events.     

西安白鹿塬北缘黄土边坡稳定的可靠度分析

在西安白鹿塬北缘实测了14个黄土自然边坡断面,建立了地质模型,通过采样测试并收集已有的测试资料,获得了各时代黄土地层的物理力学参数,将Morgenstern-Price法稳定性计算公式作为极限状态方程,分别采用Monte-Carlo法和Duncan法进行了边坡稳定的可靠度分析。结果表明:采用Monte-Carlo法和Duncan法得到的14个边坡稳定系数分别为1.11～1.41和1.09～1.33,显示这些边坡处于基本稳定—稳定状态;采用上述两种方法得到的边坡可靠指标分别为0.56～1.79和0.39～1.60,得到的失效概率分别为3.4%～29.0%和5.5%～34.8%,并且共有75%的边坡失效概率大于10%,失效可能性较大。统计结果表明:白鹿塬区边坡的坡高和坡度存在负相关性。低而陡的边坡潜在最危险滑面剪出口较高,失效概率较小;坡高达到50m及以上时,边坡高而缓,剪出口较低,失效概率较大,其中河流下切深,有N2泥岩出露的极高边坡,稳定性最差。Duncan法求解的稳定系数略小于Monte-Carlo法求得的结果,而前者求解的失效概率略大于后者,两种方法计算结果较为接近。由于Duncan法理论简单,计算量小,更宜于在实际工程中应用。     

Surface thermal centroid anomaly of the eastern equatorial Pacific as a unified Niño index

By analyzing the variability of global SST(sea surface temperature) anomalies,we propose a unified Ni o index using the surface thermal centroid anomaly of the region along the Pacific equator embraced by the 0.7°C contour line of the standard deviation of the SST anomalies and try to unify the traditional Ni o regions into a single entity.The unified Ni o region covers almost all of the traditional Ni o regions.The anomaly time series of the averaged SST over this region are closely correlated to historical Ni o indices.The anomaly time series of the zonal and meridional thermal centroid have close correlation with historical TNI(Trans-Ni o index) indices,showing differences among El Ni o(La Ni a) events.The meridional centroid anomaly suggests that areas of maximum temperature anomaly are moving meridionally(although slightly) with synchronous zonal movement.The zonal centroid anomalies of the unified Ni o region are found helpful in the classification of the Eastern Pacific(EP)/Central Pacific(CP) types of El Ni o events.More importantly,the zonal centroid anomaly shows that warm areas might move during a single warming/cooling phase.All the current Ni o indices can be well represented by a simple linear combination of unified Ni o indices,which suggests that the thermal anomaly(SSTA) and thermal centroid location anomaly of the unified Ni o region would yield a more complete image of each El Ni o/ La Ni a event.     

Numerical simulation and preliminary analysis on ocean waves during Typhoon Nesat in South China Sea and adjacent areas

Using the wave model WAVEWATCH III(WW3), we simulated the generation and propagation of typhoon waves in the South China Sea and adjacent areas during the passage of typhoon Nesat(2011). In the domain 100°–145°E and 0°–35°N, the model was forced by the cross-calibrated multi-platform(CCMP) wind fi elds of September 15 to October 5, 2011. We then validated the simulation results against wave radar data observed from an oil platform and altimeter data from the Jason-2 satellite. The simulated waves were characterized by fi ve points along track using the Spectrum Integration Method(SIM) and the Spectrum Partitioning Method(SPM), by which wind sea and swell components of the 1D and 2D wave spectra are separated. There was reasonable agreement between the model results and observations, although the WW3 wave model may underestimate swell wave height. Signifi cant wave heights are large along the typhoon track and are noticeably greater on the right of the track than on the left. Swells from the east are largely unable to enter the South China Sea because of the obstruction due to the Philippine Islands. During the initial stage and later period of the typhoon, swells at the fi ve points were generated by the propagation of waves that were created by typhoons Haitang and Nalgae. Of the two methods, the 2D SPM method is more accurate than the 1D SIM which overestimates the separation frequency under low winds, but the SIM method is more convenient because it does not require wind speed and wave direction. When the typhoon left the area, the wind sea fractions decreased rapidly. Under similar wind conditions, the points located in the South China Sea are affected less than those points situated in the open sea because of the infl uence of the complex internal topography of the South China Sea. The results reveal the characteristic wind sea and swell features of the South China Sea and adjacent areas in response to typhoon Nesat, and provide a reference for swell forecasting and offshore structural designs.     

Comparison of different sampling strategies for debris flow susceptibility mapping: A case study using the centroids of the scarp area,flowing area and accumulation area of debris flow watersheds

The quality of debris flow susceptibility mapping varies with sampling strategies. This paper aims at comparing three sampling strategies and determining the optimal one to sample the debris flow watersheds. The three sampling strategies studied were the centroid of the scarp area(COSA), the centroid of the flowing area(COFA), and the centroid of the accumulation area(COAA) of debris flow watersheds. An inventory consisting of 150 debris flow watersheds and 12 conditioning factors were prepared for research. Firstly, the information gain ratio(IGR) method was used to analyze the predictive ability of the conditioning factors. Subsequently, 12 conditioning factors were involved in the modeling of artificial neural network(ANN), random forest(RF) and support vector machine(SVM). Then, the receiver operating characteristic curves(ROC) and the area under curves(AUC) were used to evaluate the model performance. Finally, a scoring system was used to score the quality of the debris flow susceptibility maps. Samples obtained from the accumulation area have the strongest predictive ability and can make the models achieve the best performance. The AUC values corresponding to the best model performance on the validation dataset were 0.861, 0.804 and 0.856 for SVM, ANN and RF respectively. The sampling strategy of the centroid of the scarp area is optimal with the highest quality of debris flow susceptibility maps having scores of 373470, 393241 and 362485 for SVM, ANN and RF respectively.     

一种新的振幅滤波法在化磁极中的应用

本文针对低纬度地区频率域化磁极存在的问题，在频谱分析的基础上，提出了一种新的滤波方法即振幅滤波法。该方法能将低纬度地区化极磁场的频谱恢复到垂直磁化磁场的频谱，大大提高了低纬度地区化磁极的精度。