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ANALYSES ON CURRENT SITUATION, CAUSES OF FORMATION, AND WAY OF MANAGEMENT OF DESERTIFICATION IN WESTERN NORTHEAST PLAIN OF CHINA
中国东北平原西部荒漠化现状、成因及其治理途径研究
Qiu Shanwen,Zhang Bai,Wang Zhichun,
裘善文,张柏,王志春
第四纪研究 , 2005,
Abstract: 中国东北平原西部土地荒漠化，主要表现为土地沙漠化和土地盐碱化，它属于荒漠化的两种类型。东北平原西部分布着科尔沁沙地和松嫩沙地，前者是全国五大沙漠之一。文章全面、系统地对该地区编制了1：1000000荒漠化图和量算出土地沙漠化面积。东北平原西部土地沙漠化面积为72280．6km^2，占土地总面积的22．2％。自20世纪50年代至80年代末，土地沙漠化面积迅速扩大，平均每年以1．5％～3．7％的速度递增；自90年代以来，沙漠化呈现出逆转趋势，但就总体而言，沙漠化发展仍然大于逆转。东北平原西部土地盐碱化面积33850．79km^2，占土地总面积10．44％，主要分布在松嫩平原，面积为23329．19km^2，占土地总面积15．2％，它是世界上苏打盐碱化土壤的三大片之一，土地盐碱化每年以1．4％～2．5％速率正在发展。所以，该地区的土地荒漠化，不仅制约着当地农、牧业和农村经济的发展，影响周围和毗邻国家的生态环境安全，而且已危及当地人民的生存。东北平原西部荒漠化的形成有自然因素和人为因素，前者有物源和气候变化等原因，后者有草原超载过牧、滥垦、滥伐滥櫵、乱挖，河流上中游修建水库等原因，以及冻融作用的特殊原因，致使荒漠化形成和发展。文章总结了该地区沙漠化正、逆过程的演变，并提出荒漠化的治理应根据荒漠化的不同类型，采用不同的治理模式、适用技术和治理途径。
Least Squares Problems in Orthornormalization
Shanwen Hu
Mathematics , 2012,
Abstract: For any $n$-tuple $(\alpha_1,...,\alpha_n)$ of linearly independent vectors in Hilbert space $H$, we construct a unique orthonormal basis $(\epsilon_1,...,\epsilon_n)$ of $span\{\alpha_1,...,\alpha_n\}$ satisfying: $$\sum_{i=1}^n\|\epsilon_i-\alpha_i\|^2\le\sum_{i=1}^n\|\beta_i-\alpha_i\|^2$$ for all orthonormal basis $(\beta_1,...,\beta_n)$ of $span\{\alpha_1,...,\alpha_n\}$. We study the stability of the orthornormalization and give some applications and examples.
Le système d'Euler de Kato
Shanwen Wang
Mathematics , 2012,
Abstract: This article is devoted to Kato's Euler system, which is constructed from modular unites, and to its image by the dual exponential map (so called Kato's reciprocity law). The presentation in this article is different form Kato's original one, and dual exponential map in this article is a modification of Colmez's construction in his Bourbaki talk.
Le système d'Euler de Kato en famille (I)
Shanwen Wang
Mathematics , 2012,
Abstract: This article is the first article of a serie of articles on the generalization of Kato's Euler system. The main subject of this article is to construct a family of Kato's Euler systems and a family of Kato's explicit reciprocity laws over the weight space, which interpolate the corresponding classical objects.
Le système d'Euler de Kato en famille (II)
Shanwen Wang
Mathematics , 2013,
Abstract: This article is the second article on the generalization of Kato's Euler system. The main subject of this article is to construct a family of Kato's Euler systems over the cuspidal eigencurve, which interpolate the Kato's Euler systems associated to the modular forms parametrized by the cuspidal eigencurve. We also explain how to use this family of Kato's Euler system to construct a family of distributions on $Z_p$ over the cuspidal eigencurve; this distribution gives us a two variable $p$-adic L function which interpolate the $p$-adic L function of modular forms.
Formation Background of the Zhalong Wetland and its Eco- environmental Significance
扎龙湿地的形成背景及其生态环境意义
YIN Zhiqiang,QIN Xiaoguang,LIU Jiaqi,QIU Shanwen,
殷志强,秦小光,刘嘉麒,裘善文
地理科学进展 , 2006,
Abstract: Zhalong wetland locates at the western part of Heilongjiang province and was developed from the terminal lake of the Wuyuer river. In this paper, the geological environment of the Zhalong area and the relationships among the Zhalong wetland, the Nenjiang river and the Songnen desert were studied by field survey, soil sample analysis and remotely sensed image interpretation. It was found that the desert from Qiqihaer to Daqi consisted of NW- extended dunes and saline, forming a NE - extended dune belt with Keerqin desert together. The desert was mainly developed from the last glacial period. After that, the Nenjiang river flowed through the dune area and rebuilt the dunes and a lot of yoke lakes were left in Zhalong area. Because of the crustal tectonic uplift in the Zhalong area, the Nenjiang river moved westwards and Wuyuer river became an inner river which terminal lake evolved and developed as the present Zhalong wetland eventually. So the environmental evolution of the Zhalong area since the last glacial period was concluded as: the wind- blown dune belt formed → the Nenjiang river rebuilt the dune belt → the Nenjiang river westwardly migrated and the Wuyuer river became an inner river → the terminal lake of the Wuyuer river evolved to the Zhalong wetland. Therefore, the Zhalong wetland and the Lianhuan lake developed on an once- existed desert, suggesting that the ecoenvironment of the area is the frailest in the whole Nenjiang watershed. It means that the salinification and desertation in the area would rapidly develop and severely affect the eco- environment of the Qiqihaer- Daqi area if the Zhalong wetland disappeared.
DEVELOPMENT AND EVOLUTION OF HORQIN SANDY LAND AND ANCIENT HYDROLOGICAL NETWORKS
科尔沁沙地及其古水文网的演化变迁
Qin Xiaoguang,Liu Jiaqi,Qiu Shanwen,Yin Zhiqiang,
秦小光,刘嘉麒,裘善文,殷志强
第四纪研究 , 2010,
Abstract: In Horqin region,the formation and development of sandy land was closely related to the change and evolution of ancient rivers.In the paper,the macroscopic features of sandy land and drainage network were carefully analyzed according to remotely sensed images and field investigations.It was found that there were five identifiable stages of drainage network,codes as paleochannel-Ⅰ to -Ⅴ.The distribution characteristics of each drainage network stage were different from other's.There were at least four activation stages of desert.The paleochannel-Ⅴ might develop before the desert-Ⅱ and -Ⅲ and might form before the last glacial period,or an earlier period,such as midPleistocene.In the stage,rivers in Horqin areas flowed into the paleo-Songliao lake.The paleochannel-Ⅳ formed when the desert-Ⅱ and/or-Ⅲ developed.In the stage that might be the last glacial period,rivers in Horbin and the paleo-Songliao lake shrank and the rivers disappeared in deserts and did not flow into the paleo-Songliao lake.The paleochannel-Ⅲ developed after the desert-Ⅱ and -Ⅲ when may be the last deglaciation period.In the stage,temperature-rising result in a large amount of snow and ice melt-water to flow into rivers and overflow into lowlands between sand ridges to connect the ancient-Xilamulun river,the ancient-Laoha river and the ancient-Jiaolai river.The paleochannel-Ⅱ might form during the Holocene Optimal period.In the stage corresponding to the desert-Ⅰ stage,the uniform west-Liao river formed and there were several times of desert activation and dormancy.The river-Ⅰ developed at present and belong to the desert-Ⅰ stage.Most active deserts distributed in the Wengniute area.
Ammonia as a Suitable Fuel for Fuel Cells
Rong Lan,Shanwen Tao
Frontiers in Energy Research , 2014, DOI: 10.3389/fenrg.2014.00035
Abstract: Ammonia, an important basic chemical, is produced at a scale of 150 million tons per year. Half of hydrogen produced in chemical industry is used for ammonia production. Ammonia containing 17.5 wt% hydrogen is an ideal carbon-free fuel for fuel cells. Compared to hydrogen, ammonia has many advantages. In this mini-review, the suitability of ammonia as fuel for fuel cells, the development of different types of fuel cells using ammonia as the fuel and the potential applications of ammonia fuel cells are briefly reviewed.
$C^*$-algebras generated by three projections
Shanwen Hu,Yifeng Xue
Mathematics , 2012,
Abstract: In this short note, we prove that for a $C^*$-algebra $\aa$ generated by $n$ elements, $M_{k}(\tilde{\aa})$ is generated by $k$ mutually unitarily equivalent and almost mutually orthogonal projections for any $k\ge \de(n)=\min\big\{k\in\mathbb N\,|\,(k-1)(k-2)\ge 2n\big\}$. Then combining this result with recent works of Nagisa, Thiel and Winter on the generators of $C^*$--algebras, we show that for a $C^*$-algebra $\aa$ generated by finite number of elements, there is $d\ge 3$ such that $M_d(\tilde A)$ is generated by three mutually unitarily equivalent and almost mutually orthogonal projections. Furthermore, for certain separable purely infinite simple unital $C^*$--algebras and $AF$--algebras, we give some conditions that make them be generated by three mutually unitarily equivalent and almost mutually orthogonal projections.
Completeness of $n$--tuple of projections in $C^*$--algebras
Shanwen Hu,Yifeng Xue
Mathematics , 2012,
Abstract: Let $(P_1,...,P_n)$ be an $n$--tuple of projections in a unital $C^*$--algebra $\aa$. We say $\pn$ is complete in $\aa$ if $\aa$ is the linear direct sum of the closed subspaces $P_1\aa,...,P_n\aa$. In this paper, we give some necessary and sufficient conditions for the completeness of $\pn$ and discuss the perturbation problem and topology of the set of all complete $n$--tuple of projections in $\aa$. Some interesting and significant results are obtained in this paper.
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