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231.
以山区高空间分辨率的DEM数据为主要数据源,在提取纬度、坡度、坡向等相应的地形要素栅格数据的基础上,利用GIS技术对山区可照时间的空间分布进行了模拟,实现了山区可照时间空间分布规律的可视化表达,分析了山区可照时间的空间分布特征,对于山区的农业、林业和生态环境等方面的研究具有重要意义. 相似文献
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Jun Sekine 《Applied Mathematics and Optimization》2006,54(2):131-158
The dual optimization problem for the exponential hedging problem is addressed with a cone constraint. Without boundedness
conditions on the terminal payoff and the drift of the Ito-type controlled process, the backward stochastic differential equation,
which has a quadratic growth term in the drift, is derived as a necessary and sufficient condition for optimality via a variational
method and dynamic programming. Further, solvable situations are given, in which the value and the optimizer are expressed
in closed forms with the help of the Clark-Haussmann-Ocone formula. 相似文献
234.
Yangyang Jiang Chen Guo Huizhou Liu 《中国颗粒学报》2007,5(1):130-133
A magnetically rotational reactor (MRR) has been developed and used in absorbing benzene emissions. The MRR has a permanent magnet core and uses magnetic ionic liquid [bmim]FeCl4 as absorbent. Benzene emissions were carried by N2 into the MRR and were absorbed by the magnetic ionic liquid. The rotation of the permanent magnet core provided impetus for the agitation of the magnetic ionic liquid, enhancing mass transfer and making benzene better dispersed in the absorbent. 0.68 g benzene emissions could be absorbed by a gram of [bmim]FeCl4, 0.27 and 0.40 g/g higher than that by [bmim]PF6 and [bmim]BF4, respectively. The absorption rate increased with increasing rotation rate of the permanent magnet. 相似文献
235.
We report X-ray absorption near edge structures (XANES) study of CeAl2 thin films of various thicknesses, 40-120 nm, at Al K- and Ce L3-edges. The threshold of the absorption features at the Al K-edge shifts to the higher photon energy side as film thickness decreases, implying a decreased in Al p-orbital charges. On the other hand, from Ce L3-edge spectra, we observed a decrease in the 5d4f occupancy as the surface-to-bulk ratio increases. The valence of Ce in these thin films, as revealed by the Ce L3-edge spectral results, is mainly trivalent. From a more detailed analysis we found a small amount of Ce4+ contribution, which increases with decreasing film thickness. Our results indicate that the surface-to-bulk ratio is the key factor which affects the electronic structure of CeAl2 thin films. The above observations also suggest that charge transfer from Al to Ce is associated with the decrease of the film thickness. 相似文献
236.
LiNbO3∶Cr∶Cu晶体吸收特性及非挥发全息存储研究 总被引:1,自引:1,他引:0
研究了LiNbO3∶Cr∶Cu晶体的吸收特性,发现LiNbO3∶Cr∶Cu(含0.14 wt.% Cr2O3 和 0.011 wt.% CuO)晶体存在两个明显的吸收峰,中心波长分别位于480 nm和660 nm; 随着Cr的含量逐渐减小,Cu的含量逐渐增大,短波段不存在明显吸收峰,掺Cr的含量越大,中心波长在660 nm处的吸收越大;633 nm红光虽然位于中心波长为660 nm的吸收峰内,但它无助于光折变过程.分别采用390 nm紫外光和488 nm蓝光作为敏化光,514 nm绿光作为记录光的记录方案,实现了非挥发全息记录,掺入适量的Cr( 比如NCr=2.795×1025 m-3,NCr/ NCu=1)有助于全息记录性能的提高. 相似文献
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Ping-xing Chen Jian-ming Cai Zheng-wei Zhou Guang-can Guo 《量子光学学报》2006,12(B08):72-73
The second law of thermodynamics is one of the most fundamental and for-reaching laws of physics. It teaches us that when a closed system undergoes a thermodynamic process the entropy of the system never decreases; it increases, or at least remains constant. If the entropy increases the thermodynamic process is irreversible, otherwise it is reversible. Only ideal thermal process is reversible. In classical world a great number of facts have proved the second law is true. But in quantum world since the quantum coherence and correlations exist we are not sure the second law is still true, at least in principle. This is because that: 1. on the microscopic level the irreversibility is conflict with the reversibility of all fundamental physical laws ; 2. there are not enough evidences to show it is true in quantum world. 相似文献