Geostatistics with the Matern semivariogram model: A library of computer programs for inference, kriging and simulation

In many modern applications of geostatistics in the earth sciences, the empirical information is abundant and with complete spatial coverage (e.g. satellite sensor images). In these cases, a critical characteristic of spatial variability is the continuity of the random field that better models the natural phenomenon of interest. Such continuity describes the smoothness of the process at very short distances and is related to the behaviour of the semivariogram near the origin. For this reason, a semivariogram model that is flexible enough to describe the spatial continuity is very convenient for applications. A model that provides such flexibility is the Matern model that controls continuity with a shape parameter. The shape parameter must be larger than zero; a value larger than 1 implies a random field that is m-times mean square differentiable if the shape parameter is larger than m. A package of computer programs is provided for performing the different steps of a geostatistical study using the Matern model and the performance and implementation are illustrated by an example.     

关于穆斯堡尔谱的数学模型和数据拟合的看法

一、引言 运用计算机解穆斯堡尔谱的方法,在许多文献中都作了详细介绍。我们通过大量计算,常常发现实测计数的残差的加权平方和X~2的值在统计假设检验中被拒绝。文献[4]对这类现象产生的原因从仪器、物理和化学等方面作了详尽的分析。经过分析研究,我们认为问题主要可能还在数理统计方面。我们发现,近代文献中关于穆斯堡尔谱数学模型中的误差     

Establishment of accuracy limits and standards for comparative thermal conductivity measurements

New techniques have been developed for reducing thermal conductivity data from thermal comparative measurements. The first of these techniques is based on making a Taylor-series expansion of the stack centerline temperature profile. The result is an expression giving the ratio of sample to reference conductivities at any temperature as a function of measured quantities, the stack thermocouple readings and stack element thicknesses. The conventional formula presently used to reduce comparative conductivity data is shown to be a special result of the general analysis. A second technique involves the use of linear least-squares (LS) techniques to derive both the sample and the reference conductivities from the measured data. The LS technique provides the coefficients for a polynomial temperature expansion of the reference and sample conductivities directly. Use of the new techniques is illustrated in a reduction of some comparative data on the conductivities of Pyrex 7740 and Pyroceram 9606. It is shown that a highly self-consistent pair of conductivity functions can be derived for these two commonly used reference materials if the conductivity vs temperature relation for Pyrex is modified slightly from its recommended value. The Pyroceram conductivity results from the comparative measurements are in good agreement with a conductivity derived from pulse diffusivity and differential scanning calorimetry measurements and also in good agreement with the recommended Pyroceram conductivity function.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

An Initial Experimental Assessment of the Dynamic Modelling in UML

The goal of this empirical study is to compare the semantic comprehension of three different notations for representing the dynamic behaviour in unified modelling language (UML): (a) sequence diagrams, (b) collaboration diagrams, and (c) state diagrams. Eighteen students of Informatics analysed the three types of diagrams within three different application domains. We performed a 3 × 3 factorial experimental design with repeated measures. The metrics collected were total time and total score. The main conclusion of this study is that the comprehension of the dynamic modelling in object-oriented designs depends on the diagram type and on the complexity of the document. The software project design written in the UML notation is more comprehensible, when the dynamic behaviour is modelled in a sequence diagram. While if it is implemented using a collaboration diagram, the design turns out to be less comprehensible as the application domain, and consequently, the document is more complex.     

Near-infrared spectroscopic analysis of macronutrients and energy in homogenized meals

Near-infrared (NIR) reflectance spectroscopy was evaluated as a rapid and environmentally benign technique for the simultaneous determination of macronutrients and energy in commercially available, packaged meals. Reflectance spectra (400–2498 nm) of homogenized meals were obtained with a dispersive NIR spectrometer. Protein and moisture were measured by AOAC reference methods, total fat by a semi-automated acid hydrolysis, solvent extraction, gravimetric method and total carbohydrate calculated. Energy was calculated using Atwater factors. Using multivariate analysis software, PLS models (n = 113–115 products) were developed to relate NIR spectra of homogenized meals to the corresponding reference values. The models predicted components and energy in validation samples (n = 37–38 products), overall, with r² of above 0.96. Ratios of deviation to performance were between 3.6 and 6.6, and indicated adequacy of the models for screening, quality control, or process control. Performance of the models varied substantially when used to predict sub-groups of meals within the validation set.     

Theory analysis and system identification methods on thermal dynamics characteristics of ballscrews

Empirical model of machine tools on thermal error has been widely researched, which can compensate for thermal error to some extent but not suitable for thermal dynamic errors produced by dynamic heat sources. The thermoelastic phenomenon of unidimensional heat transfer of ballscrews influenced by changeable heat sources is analyzed based on the theory of heat transfer. Two methods for system identification (the least square system identification and BP artificial neural network (ANN) system identification) are put forward to establish a dynamic characteristic model of thermal deformation of ballscrews. The model of thermal error of the X axis in a feed system of DM4600 vertical miller is established with a fine identification effect. Comparing the results of the two identification methods, the BP ANN system identification is more precise than the least square system identification.     

Timing error estimation for baseband multicarrier modulation

In this paper, the topic of timing error estimation for baseband discrete multitone modulation is addressed in the context of high‐speed digital subscriber line applications. To the authors' best knowledge, this problem is sparsely and not in depth treated in the literature. In this study the modified Cramer–Rao lower bound is derived, two conventional estimators are considered and a new one is proposed. Behavior of these estimators is evaluated in terms of bias, variance and computational complexity in a wide variety of scenarios, concluding that the proposed estimator appears to be superior in all instances. Copyright © 2008 John Wiley & Sons, Ltd.     

基于PLS-LSSVM方法的湿法炼锌过程预测建模

在湿法炼锌过程中,沉铁工序具有流程长、化学反应耦合强和物理沉降过程复杂的特点.针对这一特点,提出基于PLS-LSSVM的预测建模方法.PLS能有效处理复杂冶金生产过程中的非线性、多输入和数据相关性等特性.同时,针对建模过程中LS-SVM两个重要参数的优化选择,提出免疫文化差分进化算法.仿真结果表明,本文提出的基于PLS-LSSVM的预测模型能取得较好的预测结果,为解决沉铁过程铁渣品位实时检测提供了一种有效可行的方法.     

多孔泄水闸侧向环流及脉动压力试验研究

三孔泄水闸的水工模型试验表明 ,单孔泄流会在消力池内产生侧向环流 .使作用在消力池底板上的脉动压力比底流水跃显著增加 ;使跃后水深小于相应的共轭水深 ,无法形成底流水跃的表面水滚 .建议三孔泄水闸正常泄水时 ,优先选用三孔同时泄水     

On the Triple Square and the Diagonal of the Golden Section

Geometer Mark Reynolds demonstrates the use of an ancient system for new ways of thinking and seeing: on the triple square and the diagonal of the Golden Section.