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171.
172.
针对高分辨率影像上日光温室的信息提取问题,该文提出了利用支持向量机、最近邻算法结合纹理特征在不同层上分别提取连片日光温室和独栋日光温室的方法。实验表明:纹理特征能提高分类精度,在大尺度的层上,分类精度提升幅度较大,但在小尺度的层上,分类精度提升幅度会比较小;并不是参与运算特征数越多,分类精度越高,多数情况下光谱+纹理组合的分类精度最高;提取连片日光温室的最优方案是支持向量机和光谱+形状+纹理(7像素×7像素),总精度为92.86%,Kappa系数为0.90,而提取独栋日光温室最优方案为SVM和光谱+纹理(11像素×11像素),总精度为88.39%,Kappa系数为0.86。 相似文献
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Oded Navon Anatoly Chekhmir Vladimir Lyakhovsky 《Earth and Planetary Science Letters》1998,160(3-4):763-776
We examine the physics of growth of water bubbles in highly viscous melts. During the initial stages, diffusive mass transfer of water into the bubble keeps the internal pressure in the bubbles close to the initial pressure at nucleation. Growth is controlled by melt viscosity and supersaturation pressure and radial growth under constant pressure is approximately exponential. At later stages, internal pressure falls, radial growth decelerates and follows the square-root of time. At this stage it is controlled by diffusion. The time of transition between the two stages is controlled by the decompression, melt viscosity and the Peclet number of the system. The model closely fit experimental data of bubble growth in viscous melts with low water content. Close fit is also obtained for new experiments at high supersaturation, high Peclet numbers, and high, variable viscosity. Near surface, degassed, silicic melts are viscous enough, so that viscosity-controlled growth may last for very long times. Using the model, we demonstrate that bubbles which nucleate shortly before fragmentation cannot grow fast enough to be important during fragmentation. We suggest that tiny bubbles observed in melt pockets between large bubbles in pumice represent a second nucleation event shortly before or after fragmentation. The presence of such bubbles is an indicator of the conditions at fragmentation. The water content of lavas extruded at lava domes is a key factor in their evolution. Melts of low water content (<0.2 wt%) are too viscid and bubbles nucleated in them will not grow to an appreciable size. Bubbles may grow in melts with 0.4 wt% water. The internal pressure in such bubbles may be preserved for days and the energy stored in the bubbles may be important during the disintegration of dome rocks and the formation of pyroclastic flows. 相似文献
175.
Distribution and environmental impact of coal-mining wastes in Upper Silesia, Poland 总被引:8,自引:0,他引:8
About 50 million tonnes/year of waste rock from coal-mining is generated in the limited area of the thickly populated Upper
Silesian Coal Basin (USCB) in Poland. There are 380 coal-mining waste dumps, including 76 active dump sites covering over
2,000 ha. About 15-16 million tonnes/year of waste rock is being reused for civil engineering purposes in the same area. This
brings about a problem of ground water deterioration by constituents leached from waste rock exposed to atmospheric conditions.
The major factors determining the ground water contamination potential from waste rock are chloride salinity, sulfur content
and acid generation potential. The concept behind the presented studies was to provide data for correct evaluation and prediction
of contaminant release from the waste rock, based on the characterization of coal-mining waste properties, as well as on long-term
laboratory, lysimetric and field studies. The results show that coal-mining waste dumps can be a long-term source of ground
water contamination, lasting for decades and increasing with time. Ground water down-gradient from the disused 15–30-years-old
part of the studied dump displays high and increasing acidification, high TDS, SO4, and the highest, still increasing concentrations of Mn, Fe and Zn. Cost-effective and efficient pollution control measures,
similar to the presented design and construction elements of the dump site, can mitigate the negative environmental impacts.
Received: 3 July 1997 · Accepted: 9 September 1998 相似文献
176.
基于卫星遥感图象纹理特征的云类识别方法及软件设计 总被引:4,自引:0,他引:4
介绍了基于卫星遥感资料,运用纹理学识别云类的原理、方法及软件设计。理论与实际分析表明,不同的云类对纹理敏感,纹理特征量是识别云类的良好因子,软件设计充分考虑了模块化,可视化与交互性。 相似文献
177.
This paper presents two models of texture of carbon materials possessing porosity. For both models, RMAX, RINT and RMIN values of reflectance have been calculated by modified Ting's 3A method [Ting, F.T.C., 1978. Petrographic techniques in coal analysis. In: C. Karr (Ed.), Analytical Methods for Coal and Coal Products, Vol. 1. Academic Press, New York, 1978, pp. 3–25]. It has been found that the reflectance indicating surface (RIS) for the studied models of texture changes from a biaxial negative up to a biaxial positive one (the type A texture) depending on the shape and size of pores. In particular case, for the type B texture and the isometry of pores, a uniaxial negative RIS is merely obtained. 相似文献
178.
A wind tunnel investigation of particle segregation,ripple formation and armouring within sand beds of systematically varied texture
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This paper reports on a wind tunnel investigation of particle segregation, ripple formation and surface armouring within sand beds of systematically varied particle size distribution, from coarsely skewed to bimodal. By design, the system was closed with no external inputs of mass from an external particle feed. Particles too coarse to travel in saltation for the given range in wind speed were dyed red in order to distinguish them in optical images from finer sand particles, which could be entrained into the unidirectional airflow. A 3D laser scanner measured the changing bed topography at regular time intervals during 18 experiments involving varied combinations of wind speed and bed texture. Image classification techniques were used to investigate the coincident self‐organization of the two populations of particles, as distinguished by their colour. As soon as saltation commenced, some of the red particles segregated into thin discontinuous patches. Particle trapping and sheltering on these rough patches was strongly favoured, causing them to grow preferentially. During the earliest stages of formation, bedform growth coincided with: (i) rapid coarsening of the surface texture; and (ii) the merging of proto‐ripple ‘crests’ to generate larger rhythmic bedforms of lower frequency. Consistent with previous work, ripple size was observed to increase under stronger winds when not exceeding the threshold for entrainment of the coarse‐mode or red particles from the crest. With declining rates of mass transport and particle segregation as the bed surface armoured, and the consequent deceleration of ripple propagation through to the end of each experiment, all surfaces eventually attained a steady‐state morphometry. At saturation, the largest ripples developed on beds having the lowest initial concentration of red particles. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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180.
城市街道景观三维可视化的快速实现 总被引:4,自引:1,他引:3
提出了融合车载序列影像和二维矢量地图、快速实现城市街道景观三维可视化的方法。实验证明了该方法的有效性。 相似文献