不同时期土壤有机碳(SOC)空间格局研究的主要方法

土壤有机碳作为陆地生态系统中的一个区域化随机变量,在系统内部垂直和水平发生变化的同时与大气圈和生物圈这两个碳库之间产生循环作用。为了揭示土壤有机碳的空间分布特性,传统统计学、地统计学、遥感与地理信息系统等方法被相继引入且逐渐走向成熟,其中利用遥感与地理信息系统相结合的方法来反演土壤有机碳库储量及其空间分布格局受到了越来越多的专家学者所推崇。本文在对不同方法基本理论进行简单阐述的基础上,介绍了它们在土壤有机碳的空间分布格局的研究中所取得的一些成果,并就遥感技术在反演表层土壤有机碳的空间分布格局中的应用前景进行了展望。     

Excel分析工具库在统计中的应用

本文举例介绍了利用Excel分析工具库进行统计的方法。     

苏南典型地区土壤颗粒的空间变异特征

在地统计学和GIS的支持下,以半方差函数为基本工具,分析了苏南典型地区耕层土壤颗粒的空间变异特征,并运用块段普通克立格法(BlockKriging)进行最优无偏线性插值,制作了不同粒径土壤颗粒的空间分布图。结果表明,研究区域不同粒径土壤颗粒在较大的范围内存在着空间相关性,砂粒和粉砂的空间相关距离达到243km,粘粒也达到81km;不同粒径土壤颗粒由结构性因素引起的空间变异性达到70%以上,反映了土壤颗粒在研究区域内具有较强的空间自相关性。Kriging插值结果更直观地反映了研究区域土壤颗粒的空间变异特征。     

Practical kriging in three dimensions

Little has been published to date on the practical difficulties of ore reserve estimation in three-dimensional deposits. Some authors have suggested condensing the problem into two dimensions, but this is not always practicable or desirable. A suggestion and a FORTRAN IV Function Segment are provided which may alleviate some of these difficulties.     

稻田土壤养分的空间变异性研究

本研究以嘉善县陶庄农场内一块5.1hm2的水稻田为研究区,区内不规则采样,共128个采样点。以土壤的pH、有机质、全磷、全氮、碱解氮、速效钾和速效磷含量为研究对象,研究其相应的统计规律,结果表明土壤各养分属性的变异系数在6.3%~35.61%之间,pH为5.3%;采用地统计的半方差函数分析,发现有机质,全氮,碱解氮和速效钾在一定范围内存在空间相关性;采用克立格方法进行最优内插,绘制了养分含量分布图,并对其空间变异进行了初步分析。     

热带低丘地区农场尺度土壤质量指标的空间变异

本文以我国热带地区海南儋州一个典型农场为样区,采用地统计学方法研究土壤质量指标的空间变异.研究选择了土壤质量评价最小数据集中的7项土壤质量指标(总有机碳,容重,粘粒含量,速效P、K,阳离子交换量,pH)进行分析,统计分析的结果表明,研究区域土壤存在酸化和养分贫瘠化现象.地统计学分析结果表明,表层土壤基底值普遍高于表下层土壤,说明表层土壤由于受随机因素影响更为强烈导致空间变异性增强.在各项土壤质量指标中,pH和土壤容重主要表现为基底效应,总有机碳、阳离子交换量,速效P、K含量以及亚表层土壤粘粒含量表现出中等空间相关性,表层粘粒含量空间变异随距离增加而增加.在GIS支持下,采用块段克立格方法(block kriging)进行各项土壤质量指标的空间内插得到指标的等级分布图.研究结果可以为进一步的土壤质量综合评价提供方法和理论依据.     

Modeling uncertainties in sodium spatial dispersion using a computational intelligence-based kriging method

Classical and geostatistical methods have been used to create continuous surfaces from sampled data. A common geostatistical method is kriging, which provides an accurate estimation based on the existing spatial structure of sample points. However, kriging is sensitive to errors in the input data, the dispersion of the sample points, and the fit of the model to the variogram. The purpose of this research is to develop a new method to address the uncertainties resulting from the input data and choice of model in the kriging method. In our approach, the existing uncertainties in the input data are modeled by fuzzy computations, and the variogram variables are optimized by a genetic algorithm. To test this new hybrid method, sodium contamination values in the Zanjan aquifer were used. The results show a general improvement in accuracy compared with the ordinary kriging method. Consideration of all equations and values in fuzzy computations highlights the complexity of the computation. Herein, the integration problems experienced by other researchers when trying to use fuzzy kriging are resolved.     

Some auxiliary functions for the spherical model of geostatistics

The tasks of evaluating the accuracy of estimates produced by geostatistics and of Kriging have been eased by the introduction of auxiliary functions. This paper gives a brief resume of the properties, uses and potentialities of auxiliary functions, followed by some computer FUNCTIONs in the FORTRAN IV language for their evaluation for the spherical or ‘Matheron’ model of the semivariogram.     

Network optimization algorithms and scenarios in the context of automatic mapping

Many different algorithms can be used to optimize the design of spatial measurement networks. For the spatial interpolation of environmental variables in routine and emergency situations, computation time and interpolation accuracy are important criteria to evaluate and compare algorithms. In many practical situations networks are not designed from scratch but instead the objective is to modify an existing network. The goal then is to add new measuring stations optimally or to withdraw existing stations with as little damage done as possible. The objective of this work is to compare the performance of different optimization algorithms for both computation time and accuracy criteria. We describe four algorithms and apply these to three datasets. In all scenarios the mean universal kriging variance (MUKV) is taken as the interpolation accuracy measure. Results show that greedy algorithms that minimize the information entropy perform best, both in computing time and optimality criterion.     

Precise calculation of the cumulative distribution function and its inverse function for Fisher's F and Student's t tests

A computer program to calculate precise solutions (exact to the limit of computer accuracy) for the cumulative distribution function of the statistical t and F distributions is detailed. A routine that makes iterative calls of this algorithm to calculate precisely the inverse function of these distributions by successive approximation is also provided. The program provided yields precise levels of probability confidence for both Fisher's F and Student's t tests, and the inverse calculation of critical values given p. It is written in a subset of BASIC which should run on any small computer, requiring only 1538 bytes on the Commodore 64.     

高职高专机械设计教学文献计量分析

文章从学科类别、期刊类别、研究基金、研究层次、作者、作者单位分布,年度分布等角度,对我国1999年以来发表的高职高专机械设计教学相关论文进行了计量统计分析。     

The design of optimal sampling schemes for local estimation and mapping of of regionalized variables—I: Theory and method

Surveys of materials at the earth's surface, especially soil, can be planned to make the best use of the resources for survey or to achieve a certain minimum precision provided the nature of spatial dependence is known already. A method is described for designing optimal sampling schemes. It is based on the theory of regionalized variables, and assumes that spatial dependence is expressed quantitatively in the form of the semi-variogram. It assumes also that the maximum standard error of a kriged estimate is a reasonable measure of the goodness of a sampling scheme. By sampling on a regular triangular grid, the maximum standard error is kept to a minimum for any given sampling, but a square grid is approximately equivalent where variation is isotropic. Given the semi-variogram for a variable, the sampling density for any prescribed maximum standard error is determined. Where variation is geometrically anisotropic, the same method is employed to determine sample spacing in the direction of maximum change, and the grid mesh elongated in the perpendicular direction in proportion to the anisotropy ratio.     

吉林公主岭土壤中砷、铬和锌含量的空间变异性及分布规律研究

在兼顾吉林省公主岭地区土壤类型与样点分布的相对均匀性的前提下 ,采集黑土、黑钙土和草甸土等土壤耕层 (0 -2 0cm )样品 70个 ,测定其全砷 (As)、铬 (Cr)和锌 (Zn)含量以及其它主要理化性质。采用经典统计学与半方差函数拟合相结合的方法 ,研究了土壤砷、铬和锌含量的空间变异性。根据半方差函数的拟合结果 ,在ArcViewGIS软件的支持下 ,编制Scripts进行克里格插值 ,以此来揭示该区域土壤砷、铬和锌含量的空间分布规律 ,并探讨这些重金属元素与主要土壤理化性质的关系     

The design of optimal sampling schemes for local estimation and mapping of regionalized variables—II: Program and examples

A FORTRAN IV program, OSSFIM, is presented for calculating estimation variances when interpolating by kriging from regular rectangular and triangular grids of data and previously-determined semi-variogram. The variances are computed for a range of grid spacings and block sizes, and the results graphed. The user chooses a block size, and can read from the appropriate graph the sample spacing corresponding to any prescribed maximum tolerable error. This is the optimal sampling scheme. Use of the program is illustrated with two examples showing different types of variation in soil. In one, the pH of topsoil is isotropic with a spherical semi-variogram and negligible nugget variance. An equilateral triangular grid is the best sampling scheme; it is approximately 10 per cent more efficient than a square grid. In the other example, variation is linear but anisotropic with a large nugget variance. In these circumstances, a triangular grid has no advantage over a rectangular one, which should be elongated in the ratio 1.88 to I in the direction of minimum variation.     

“十五”中期中部省区档案信息化基础数据统计分析

本文以《中国档案年鉴》的统计数据为主,对十五中期,中部8个省机构数量、人员数量、馆藏档案数量、计算机硬件与网络数量、电子文件与机读目录数和相对指标6组共33个指标项进行较为全面的统计分析研究。     

“十五”中期东部省区档案信息化基础统计分析

本文以《中国档案年鉴》的统计数据为主,设计了总量指标与相对指标两类6组共33个指标,对十五中期,东部11个省、市的档案信息化情况进行了量化统计分析研究。     

用Excel管理中职学生成绩

管理学生的考试成绩是教师教学工作的重要一环,本文借助Excel提供的强大数据处理能力,对学生的考试成绩进行录入、统计、分析及查询,以利提高教学成绩和工作效率。     

使用存储过程实现复杂的数据统计与分析

描述存储过程在复杂的统计查询方面的优点,并用实例说明其在复杂统计查询方面的优点所在.阐述存储过程在海量数据分析方面的优势,并结合现实说明了存储过程在海量数据分析系统优化方面的作用.     

A review of recent developments in geostatistics

This paper reviews developments in geostatistics in the period 1987 to mid-1991. The developments which are regarded as significant by the author fall broadly under six headings: simulation, indicator kriging, interval estimation, applications to hydrocarbon reservoirs and hydrology, incorporation of prior information in spatial estimation, and fuzzy kriging. A summary of significant contributions under each of these headings is given together with an assessment of their importance and application.