电源避雷器选型与安装应注意的事项

根据国际电工委员会与国家防雷规范的要求,确定电源避雷器选型与安装的最佳途径和应注意的事项。     

基于交通网络空间权重的区域经济空间相关分析——以甘肃省为例

在区域经济中,交通是联系地理空间和区域经济活动的纽带,交通的发达程度决定了各地理单元空间相互作用的广度与深度.针对不同交通模式赋以不同的权重,基于最短加权交通网络,提出新的空间权重矩阵构建方法,构建了交通网络空间权重,与各种传统空间权重一起,对比研究甘肃省各县域单元之间的区域经济的空间相关性.研究结果表明,利用交通网络空间权重生成的空间权重矩阵,能更真实地反映区域间实际的空间过程;甘肃省的区域经济具有空间相关性但不显著,核心城市经济外溢现象不明显.     

层次分析法在下垫面因子影响沙尘暴危险度研究中的应用

沙尘暴是一种危害严重的气象灾害,其形成依赖于大气环流和沙质地表两种不同密度的物理介质的相互作用,风力条件和下垫面的性质是影响沙尘暴强度和危害程度的两个重要因素。减轻沙尘暴危害的有效方法就是改善沙尘暴源地的下垫面状况,但这需要评估下垫面各因子在不同天气、气候背景条件下对沙尘暴发生的影响程度。从下垫面的角度出发,以内蒙古中西部地区为例,利用气象资料和实测数据,应用AHP方法对下垫面定性与定量因子进行综合分析,得出不同地区下垫面因子对沙尘暴发生作用的权重,为从下垫面角度研究沙尘暴危险度奠定基础。     

由计算机产生的等距离区域分界线

本文介绍一种最近由作者在美国研制的,由计算机产生等距离区域分界线的程序及其数据结构,同时给出初步的试验结果。     

特征分析模型构造原理

本文研究在矿产资源评价中适用于不同条件的,特征分析模型的构造原则和方法:建立一般特征分析模型的最大标度准则;变量权和样品关联度的不同算法和解释;基于不同相似性度量标准的矿床模型及建立广义矿化模型的方法;构造多维特征分析模型和进行定量资源评价的可能性。     

EOF迭代方案恢复夏季大气环流场的试验

本文设计了一种恢复夏季大气环流场的EOF(经验正交函数)迭代方案,并利用1951～1984年中国夏季降水距平场和北半球500hPa夏季高度距平场作镢复试验,数值试验效果较好.此项工作表明:利用某些长时间序列的资料通过EOF迭代方案恢复历史时期大气环流是可行的.     

测量平差模型的抗差最小二乘解及影响函数

抗差Ｍ估计是使用最广泛、计算较简明的抗差估计法。基于多维Ｍ估计原理，本文建立了经典测量平差函数模型的抗差解，并推导出相应的误差影响函数；为了使抗差估计适于不同类型以及不同先验精度的各类观测值的混合平差，将使用等价权原理构造抗差最小二乘解式。     

Molecular weight distribution,analytical and spectroscopic characterization of humic fractions sequentially isolated by organic solvents from a brown coal humic acid

A sequential fractionation procedure employing a series of selected mild organic solvents of different polarity has been applied for the isolation of chemically different organic fractions from a brown coal humic acid. Elemental composition, molecular weight distribution, i.r. and electron spin resonance analysis were carried out on the isolated humic fractions. They were characterized by: (a) a low polydispersity, (b) a decreasing aliphatic and increasing aromatic character along the series, (c) very different molecular weight which significantly correlated with E₄/E₆ ratios (particle aggregation and molecular association) and free radical concentrations (chemical and biochemical activity). Significant correlations were found between physico-chemical parameters of the isolated humic fractions, i.e. M_n, M_w, E₄/E₆ ratios, spins/g contents and the dielectric constants of the solvents used. This suggested the efficiency of the applied procedure in isolating chemically different organic fractions from the bulk, original humic acid.     

A digital model to evaluate the water balance in a typical hardrock environment

A digital model was designed and developed to study the water balance situation in a typical hardrock environment near Hyderabad, Andhra Pradesh. The model was calibrated over a period of six years with observed field hydrographs. An optimum error factor of 0.001 m was chosen and the computer took 47 iterations for outputting the results with the desired accuracy. Prognostic studies were carried out with progressively increasing draft conditions and water levels were observed to be declining even when the draft was less than the recharge. The analysis of the experiments further amended the belief of the earlier workers.