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Yang Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Yang Y.,University of Chinese Academy of Sciences | Su H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Su H.,Texas A&M University-Kingsville | And 3 more authors.
Journal of Applied Remote Sensing | Year: 2012

Accurate estimation of evapotranspiration (ET) has long been an important issue in hydrology. Many experimental observations indicate advection has a great impact on ET in arid and semiarid areas. However, most of the remote sensing models only focus on the vertical energy balance and deviate from reality. A revised Penman equation has been derived to estimate actual ET under normal conditions in order to account for advection. The parameter of the water availability for ET is introduced and the Ts/f (surface temperature and vegetation fraction) space is used to characterize this parameter in the revised formula. The estimates were validated using the observations measured with eddy covariance systems at the Yingke station. In 22 of all 24 days, the difference between the observations and the estimates was smaller than 70 W?m2. The correlation coefficient is 0.91 and the RMSE is 48.38 W/m2. This finding reveals that this approach is capable of providing reliable results. In addition, when considering advection, the potential ET can be 83.23 W/m 2 larger than the available energy. This finding indicates that the advection effect needs to be considered in remote sensing models in order to derive more reliable regional ET. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). Source


He R.,CAS Technical Institute of Physics and Chemistry | He R.,University of Chinese Academy of Sciences | Lin Z.S.,CAS Technical Institute of Physics and Chemistry | Zheng T.,Nanjing University of Technology | And 2 more authors.
Journal of Physics Condensed Matter | Year: 2012

The development of ultraviolet (UV) nonlinear optical (NLO) crystals demands optical materials with wide energy band gaps. Here we report first-principles studies on the electronic structures in several UV NLO borates with representative structures. Combined with model analysis, we find that the oxygen non-bonding 2p orbitals play an important role on the top of valence bands. The energy band gap can be adjusted by modifying the coordination environment around the oxygen atoms. Under ideal conditions the energy band gaps achieve 9eV if the non-bonding orbitals are totally eliminated, despite the original values varying from 6.6 to 8.3eV. © 2012 IOP Publishing Ltd. Source


Nie C.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Nie C.,University of Chinese Academy of Sciences | Li H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Yang L.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 5 more authors.
Quaternary International | Year: 2012

This study focuses on extreme temperature and extreme precipitation changes in Guangxi Province of south China, which has experienced increased numbers of climate disasters in recent years. In this paper, spatial and temporal changes in extreme temperature and extreme precipitation were reconstructed for the period 1960-2009. The method of FFT filtering was used to smooth time series of extreme temperature and extreme precipitation, linear regression to calculate linear fits, and spline interpolation to interpolate station data and estimate linear changes. The results show that the annual extreme temperature increased in most of the area during 1960-2009, especially in the northeast. The greatest increase was the extreme temperature in winter, compared to that in autumn, summer and spring in order from high to low across most of the study area. The annual extreme precipitation changed little in the first three decades and increased significantly in the last two decades, and varied with region and season. Spatially, the annual trend of extreme precipitation increased across most of the province, except in some areas of the southeast. The seasonal change trend of extreme precipitation varied greatly across different areas. © 2012 Elsevier Ltd and INQUA. Source


Yang Y.-Q.,Institute of Disaster Prevention | Hu J.-F.,National Disaster Reduction Center | Xi M.-H.,Institute of Disaster Prevention
Journal of Natural Disasters | Year: 2011

A large-scale debrisflow disaster occurred in Zhouqu County, Gansu Province on August 8, 2010, which made huge economic losses and people's death. Based on grey correlation method, the main influencing factors could be found by the analysis of influence of debris flow hazard in Zhouqu. The results show that, the heavy rainfall is direct dynamic force to cause the debris flow disaster and human's activities are the indirect reasons to lead to the geological disaster. The development of agriculture and animal husbandry has the biggest influence on debris flow in all human's factors. Author considers that the reasonable development of agriculture and animal husbandry should be planned appropriately. In addition, afforestation or converting cropland to forest should be strengthened, ecological environment impact assessment must be carried out for the new-building hydropower station to reduce natural disasters risk. Source


Lin Z.S.,CAS Technical Institute of Physics and Chemistry | Kang L.,CAS Technical Institute of Physics and Chemistry | Kang L.,University of Chinese Academy of Sciences | Zheng T.,Nanjing University of Technology | And 4 more authors.
Computational Materials Science | Year: 2012

The predictive capabilities of the density functional theory with various exchange-correlation functionals on the energy band gaps and optical properties in ultraviolet nonlinear optical (UV NLO) crystals are systematically investigated. We find that the energy band gaps of these crystals can be accurately predicted by the non-local hybrid functionals and sX-LDA functionals, but their calculated optical properties are not consistent with the experimental results compared to the usually adopted LDA or GGA functionals with the scissors corrections. Accordingly, we propose that a precise and effective strategy to study the optical properties in the UV NLO crystals without any experimental parameter should be the combination of different functional calculations. © 2012 Elsevier B.V. All rights reserved. Source

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