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81.
Thermal expansion of Mg(OH)<Subscript>2</Subscript> brucite under high pressure and pressure dependence of entropy 总被引:1,自引:1,他引:0
H.?FukuiEmail author O.?Ohtaka T.?Suzuki K.?Funakoshi 《Physics and Chemistry of Minerals》2003,30(9):511-516
An equation of state for Mg(OH)2 brucite under high-pressure and high-temperature conditions has been obtained by measuring temperature dependence of volume up to 600 K at ambient pressure and pressure dependence of volume up to 16 GPa at 300, 473, 673, and 873 K with in situ X-ray diffraction. Pressure dependence of entropy of brucite has been calculated with thermal expansion coefficient and volume which are derived from the present EoS. This dependence indicates that generation of secondary OH dipoles affects entropy. The OH dipoles probably appear around 2 GPa and the number seems not to change over 8 GPa at 300 K. 相似文献
82.
The Entropy Score and its Uses in Earthquake Forecasting 总被引:1,自引:0,他引:1
Suppose a forecasting scheme associates a probability p* with some observed outcome. The entropy score given to this forecast is then –logp*. This article provides a review of the background to this scoring method, its main properties, and its relationships to concepts such as likelihood, probability gain, and Molchans - diagram. It is shown that, in terms of this score, an intrinsic characterization can be given for the predictability of a given statistical forecasting model. Uses of the score are illustrated by applications to the stress release and ETAS models, electrical signals, and M8. 相似文献
83.
Catherine Leyx J. Cornelis Van Miltenburg Christian Chopin Lado Cemič 《Physics and Chemistry of Minerals》2005,32(1):13-18
The low-temperature heat capacity of -Mg2PO4OH was measured between 10 and 400 K by adiabatic calorimetry. No phase transition was observed over this temperature range. A relative enthalpy increment of 22,119 J mol–1 and an absolute entropy value of 127.13±0.25 J mol–1 K–1 at 298.15 K are derived from the results. The low-temperature heat-capacity data are compared with the DSC data obtained from 143 K to 775 K and show marginal differences in the common temperature range. The latter data are fitted by the polynomial
which allows extrapolation to high temperatures.Software information: WINDOWS operating system, WORD word processing, SigmaPlot diagrams exported in tiff format. 相似文献
84.
The spatial variability of each parameter affecting storm runoff must be accounted for in distributed modelling. The objective of the work reported here is to assess the effects of using distributed versus lumped hydraulic roughness coefficients in the modelling of direct surface runoff. A spatially variable data set composed of Manning roughness coefficients is used to model direct surface runoff. To assess the information content (as measured by entropy) of spatially variable data and its significance in distributed modelling, various degrees of smoothing are applied. The error resulting from smoothing the hydraulic roughness coefficients is determined by modelling overland flow using a finite element solution. The Manning roughness coefficients were taken from field measurements of the Manning roughness coefficient at 0.6 m on a 14 m hillslope. These values were then used in a numerical simulation of outflow hydrographs to investigate the dependence of error on spatial variability. Our study focuses on the characteristics of spatial data used in distributed hydrological modelling. The field sites have fractal dimensions of ≈? 1.4, which is close to a Brownian variation. The sampling interval that captures the essential spatial variability of the Manning roughness coefficient does not seem to matter due to its Brownian variation in the field sites. Hence due to the nearly uniform random distribution, measurements at 0.6 m intervals are not necessary and larger intervals would yield results that are just as acceptable provided the mean value together with a uniformly random distribution is maintained for any size of finite element or sampling resolution. Because detailed measurements of hydraulic roughness are not practically available for deterministic catchment modelling, it is important to know that larger sampling resolutions may be used than 0.6 m. 相似文献
85.
Liangzhi You Stanley Wood 《International Journal of Applied Earth Observation and Geoinformation》2005,7(4):310-323
While crop production statistics are reported on a geopolitical – often national – basis, we often need to know, for example, the status of production or productivity within specific sub-regions, watersheds, or agro-ecological zones. Such re-aggregations are typically made using expert judgments or simple area-weighting rules. We describe a new, entropy-based approach to the plausible estimates of the spatial distribution of crop areas. Using this approach tabular crop production statistics are blended judiciously with an array of other secondary data to assess the areas of specific crops within individual ‘pixels’—typically 25–100 km2 in size. The information utilized includes crop production statistics, farming system characterization, satellite-based interpretation of land cover, biophysical crop suitability assessments, and population density. An application is presented in which Brazilian state level production statistics are used to generate pixel level crop area data for eight crops. To validate the spatial allocation we aggregated the pixel estimates to obtain synthetic estimates of municipality level areas in Brazil, and compared those estimates with actual municipality statistics. The approach produced extremely promising results. We then examined the robustness of these results compared to simplified approaches to spatializing crop production statistics and showed that, while computationally intensive, the cross-entropy method does provide more reliable spatial allocations. 相似文献
86.
关于熵与城市发展之探讨 总被引:5,自引:0,他引:5
城市的形成和发展是一个历史过程,如何评判城市是一个深刻的哲学命题,从熵定律角度来研究城市发展,可以帮助我们建立一种新的城市发展观。城市发展是一个不可逆过程,城市作为一个开放的系统,只要能够从外部环境得到足够的负熵流以抵消内部的熵增,城市将形成耗散结构系统并朝着进化的方向发展。未来的城市应进入低熵社会,主要途径是:建立生态城市,走可持续发展的道路;建立数字城市,实现城市社会信息化;控制城市人口,合理发展城市规模。 相似文献
87.
88.
断层形变短临前兆表现形式是多样的,并作了初步分类,丛集性高频波动是其一种重要现形式,探索了这种前兆信息的提取思路和方法,认为信息丛集度C是描述这种前兆短临信息,熵值积分平滑值G是描述中短信息较理想的特征量,震例学表明第二类前兆具有较好的预报效能,对异常判据了初步探索。 相似文献
89.
90.
The soil-covered landscape surface can be idealized from two viewpoints. The intuitive view is of a smooth, absolutely continuous surface with continuous contour lines and measurable in integral dimensions. The alternative view emphasizes the roughness, a surface of little regularity and at the limit of no contours, the appropriate measure being that of fractional Hausdorff dimension. Regularity is a local property and both idealizations need to stop far short of the limit to avoid awkward consequences. The dichotomy of viewpoint can be matched in the theory of Gaussian random fields. These, if they are smooth, are very smooth but if they are irregular they are highly irregular (erratic); there is no middle ground. This Belayev dichotomy is defined and both modes applied to the soil-covered landscape. On the one hand, if the landscape is subject to a general diffusive type degradation or more generally a Davisian downwasting regime then the curvature of the landscape surface is progressively straightened and the distribution of gradient (increments) along a typical traverse will eventually adopt a Gaussian form. Then from the irregular viewpoint the surface is ultimately well represented by a fractional Brownian surface of low Hausdorff dimension (2·0 < dim < 2·3). The Hausdorff dimension is directly related to the entropy of the landscape and as degradation proceeds both quantities decrease in value. On the other hand, if the surface is regarded as smooth and well represented by an absolutely continuous Gaussian field then the mean value of the number of upcrossings of a level or the extent of an excursion set will also be Gaussian. This analysis is restricted to one dimension; the number of times a profile curve crosses or the amount of time it spends above any given level. Predictions from both viewpoints are substantially corroborated in a map analysis of 15 sites on varied terrains in Southern England and the map analysis checked against one based upon digital tape data for one of the sites. 相似文献