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831.
Research on thermal shock resistance of mullite-bauxite-silicon carbide castable refractory 总被引:1,自引:0,他引:1
Nobuaki Chiyoda 《中国地球化学学报》2012,31(2):204-208
Effects of different silicon carbide contents on thermal shock resistance properties of mullite-bauxite castable refractory were analyzed respectively by taking the mullite,bauxite as main raw materials and taking calcium aluminate cement as a binding system.After 24 h curing in mould and another 24 h curing at 110℃ after demoulding,the samples were heated at 1000,1300 and 1500℃for 3 h in air,respectively.The bulk density,thermal expansion coefficient and thermal shock resistance were examined.The results showed that there was a great effect of content of SiC on bulk density,thermal expansion coefficient and thermal shock resistance of mullite-bauxite castable.Under the experimental conditions,the castable performed the best thermal shock resistance when w(SiC)=5%-10%. 相似文献
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833.
阐述了引入时间距离权的传统GM(1,1)模型的建模过程以及灰色模型等级的判断方法,深入分析了白化背景参数λ取值对建模精度的影响;同时针对传统λ取值的缺陷,提出使用基于实数编码的改进遗传算法(IRCGA)对其进行优化处理,并用多个工程实例分析验证了优化后的GM(1,1)模型相对传统的灰色模型及其优化模型拟合效果更好,更加贴近真实数据序列。 相似文献
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835.
抗几何攻击的高分辨率遥感影像半盲水印算法 总被引:1,自引:1,他引:0
提出了一种可有效抵抗几何攻击的高分辨率遥感影像半盲水印算法。该算法充分考虑了高分辨率遥感影像的特点,在水印嵌入方案中,对原始水印信息进行扩频处理,将水印值与最高有效位进行匹配,生成密钥矩阵,水印嵌入到最高位或次低位,并以二进制方式保存生成的密钥矩阵;在水印提取方案中,采用模板匹配技术提取出最优的水印信息。实验结果表明,该水印方案具有良好的不可见性,并且对影像的裁剪、旋转、平移、加噪、滤波等操作具有较强的鲁棒性。 相似文献
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837.
838.
Relation of the Second Type Thermal Helicity to Precipitation of Landfalling Typhoons: A Case Study of Typhoon Talim
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This study utilized the MM5 mesoscale model to simulate the landfalling process of Typhoon Talim. The simulated typhoon track,
weather patterns, and rainfall process are consistent with the observation. Using the simulation results, the relation of
the second type thermal helicity (H
2) to rainfall caused by the landfalling typhoon Talim was analyzed. The results show that H
2 could well indicate the heavy inland rainfall but it did not perform as well as the helicity in predicting rainfall during
the beginning stage of the typhoon landfall. In particular, H
2 was highly correlated with rainfall of Talim at 1-h lead time. For 1–5-h lead time, it also had a higher correlation with
rainfall than the helicity did, and thus showing a better potential in forecasting rainfall intensification. Further analyses
have shown that when Talim was in the beginning stage of landfall, 1) the 850–200-hPa vertical wind shear around the Talim
center was quite small (about 5 m s−1); 2) the highest rainfall was to the right of the Talim track and in the area with a 300-km radius around the Talim center,
exhibiting no obvious relation to low-level temperature advection, low-level air convergence, and upper-level divergence;
3) the low-level relative vorticity reflected the rainfall change quite well, which was the main reason why helicity had a
better performance than H
2 in this period. However, after Talim moved inland further, 1) it weakened gradually and was increasingly affected by the
northern trough; 2) the vertical wind shear was enhanced as well; 3) the left side of the down vertical wind shear lay in
the Lushan and Dabieshan mountain area, which could have contributed to triggering a secondary vertical circulation, helping
to produce the heavy rainfall over there; hence, H
2 showed a better capacity to reflect the rainfall change during this stage. 相似文献
839.
Cloud droplet dispersion is an important parameter in estimating aerosol indirect effect on climate in general circulation
models (GCMs). This study investigates droplet dispersion in shallow cumulus clouds under different aerosol conditions using
three-dimensional large eddy simulations (LES). It is found that cloud droplet mean radius, standard deviation, and relative
dispersion generally decrease as aerosol mixing ratio increases from 25 mg−1 (clean case) to 100 mg−1 (moderate case), and to 2000 mg−1 (polluted case). Under all the three simulated aerosol conditions, cloud droplet mean radius and standard deviation increase
with height. However, droplet relative dispersion increases with height only in the polluted case, and does not vary with
height in the clean and moderate cases. 相似文献
840.
Human systems will have to adapt to climate change. Understanding of the magnitude of the adaptation challenge at a global scale, however, is incomplete, constrained by a limited understanding of if and how adaptation is taking place. Here we develop and apply a methodology to track and characterize adaptation action; we apply these methods to the peer-reviewed, English-language literature. Our results challenge a number of common assumptions about adaptation while supporting others: (1) Considerable research on adaptation has been conducted yet the majority of studies report on vulnerability assessments and natural systems (or intentions to act), not adaptation actions. (2) Climate change is rarely the sole or primary motivator for adaptation action. (3) Extreme events are important adaptation stimuli across regions. (4) Proactive adaptation is the most commonly reported adaptive response, particularly in developed nations. (5) Adaptation action is more frequently reported in developed nations, with middle income countries underrepresented and low-income regions dominated by reports from a small number of countries. (6) There is limited reporting on adaptations being developed to take advantage of climate change or focusing on women, elderly, or children. 相似文献