【摘 要】
：
Recognizing land use changes (LUC) and evaluating their relationship with producing dust sources are considered effective to manage the environment. Taking Kermanshah Province, Iran as study area, dusty days from 2008 to 2015 were selected and dust source
【机 构】
：
Department of Geography, Faculty of Literature and Humanities, Razi University, Kermanshah 671441494
论文部分内容阅读
Recognizing land use changes (LUC) and evaluating their relationship with producing dust sources are considered effective to manage the environment. Taking Kermanshah Province, Iran as study area, dusty days from 2008 to 2015 were selected and dust sources were identified applying thermal-infrared dust index (TDI), hybrid single-particle lagrangian integrated trajectory (HYSPLIT), false col-or composite (FCC) and true color composite (TCC) of MODerate resolution Imaging Spectroradiometer (MODIS) images. Afterwards, the land use change map was produced using Landsat images in 2000 and 2015. Then, the distribution and frequency of the sources in each land-use change class and important dust production areas were specified. Eventually, two non-parametric tests including Chi-square and Kruskal-Wallis were applied to examine the relationship between LUC and dust sources. Results indicated that the distribu-tion of dust sources was not identical in the study area, and the sources were mainly generated in the areas where land-use change had occurred. In fact, different classes of LUC have different contributions to dust production, and the highest contribution refers to the de-flation in gentle slope areas and lowlands where the rangeland has been converted into agriculture land. The findings from this study are useful to manage and control dust in the identified sources.
其他文献
股票市场的价格波动以及其带来的收益率变化备受国内外专家学者的关注.在此背景下,本文主要研究长资产收益率序列波动率的变化情况,并用于上证综合指数的实例分析中.由于最常用的GARCH模型仅在观察周期较短时才充分有效,针对长资产收益率序列的波动率往往具有长记忆性,本文提出了一种改进的时变波动率模型.为使模型更好地拟合波动率的变化,本文将波动率的方差分解为条件方差与无条件方差的乘积,通过合理的模型转化,使条件方差遵循GARCH过程,无条件方差使用非参数方法(B-spline函数)拟合,并使之随时间平滑变化.通过数
Main observation and conclusionrnBoswelliains A-E (1-5),five new cembrane-type diterpenoids,were isolated from the resin of Boswellia papyifera.Their structures,determined by using spectroscopic,computational and chemical methods,demonstrate that 2-5 are
Main observation and conclusionrnThe steric and electronic properties of N-heterocyclic carbenes (NHCs) can be modified by the exocyclic substituents at the nitrogen atoms,by 1-3 atoms\' replacements of the five-membered imidazolium skeleton and by the
The karst landform is a typical ecologically vulnerable region, and the problem of karst rocky desertification in southtern and western China has led to impoverishment and a degraded local ecological environment, which severely limits local socioeconomic
Main observation and conclusionrnHistone point mutations,including missense mutations on histone H3 at positions 27 (K27M),34 (G34R/V,G34W,G34L) and 36(K36M),were identified as potential cancer driver mutations.H3.3G34R/V mutations account for pediatric g
Main observation and conclusionrnTwo discotic liquid crystalline (LC) molecules consisting of a bowl-shaped corannulene core and five-fold photoactive azobenzene branches with different paraffinic side chains were developed.Their self-assembly,photo-respo
对于贝塔负二项模型的概率参数,我们推荐并解析地计算了张损失函数下的贝叶斯估计量,张损失函数对总的高估和总的低估有相等的惩罚.该估计量使后验期望张损失最小化.在平方误差损失函数下,我们还计算了常用的贝叶斯估计量.此外,我们得到了后验期望张损失在两个贝叶斯估计量下的估计.然后,我们分别用矩法和极大似然估计法给出了贝塔-负二项模型超参数估计量的两个定理.因此,利用这两个定理估计的超参数,得到了张损失函数下概率参数的经验贝叶斯估计量.在数值模拟中,我们例证了三件事.首先,我们举例说明了贝叶斯估计量和后验期望张损失
Main observation and conclusionrnSix new meroterpenoids,bipolarinoids A-F (1-6),and two known congeners (7-8) were isolated from a soil-derived fungus Bipo-laris zeicola.Their structures were elucidated based on extensive spectroscopic techniques (includi
National urban planning, construction, and management levels have undergone qualitative changes in China since 2000. Nonetheless, problems caused by rapid urbanization are becoming increasingly promin
With the continuous development of urbanization in China, the countrys growing population brings great challenges to urban development. By mastering the refined population spatial distribution in admi