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Canonical Correlation Factors Causing the Formation of Accumulated Sand-belts along the Oasis Fringe in Hexi Corridor
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作者 Chang Zhaofeng Wang Qiangqiang +7 位作者 Zhang Jianhui Tang Jinnian Zhu Shujuan Fan Baoli Zhang Dabiao Liu Shizeng Zhang Guozhong Li Aide 《Animal Husbandry and Feed Science》 CAS 2014年第5期279-284,共6页
Accumulated sand-belts refer to those formed along the oasis fringe,especially at the upwind location,due to the accumulation of sand blocked by farmland windbreak. In the 60 years since the foundation of new China,a ... Accumulated sand-belts refer to those formed along the oasis fringe,especially at the upwind location,due to the accumulation of sand blocked by farmland windbreak. In the 60 years since the foundation of new China,a lot of trees have been planted for desertification combating in northwest and north China,thus,accumulated sand-belts were formed at the upwind location. The formation and the ecological effects of the accumulated sand-belts along the oasis fringe is a new scientific concern. To study the formation causes of these belts in Hexi corridor,21 samples were selected,and the height / width of the belts,as well as the vegetation,soil,soil moisture and climatic factors were investigated. This paper analyzed the correlation between the height / width of the belts and the vegetation,soil,soil moisture and climatic factors using the methods of variance analysis,correlation analysis and canonical correlation analysis. The results indicate that: the accumulated sand-belts take a trend of being high and wide in the east whereas low and narrow in the west,and most of the parts tend to be stable; the species on the belts are dominated by Tamarix austromongolica,the vegetation cover and the pure vegetation cover of different dominant species on the leeward slope of the accumulated sand-belts vary significantly. The canonical correlation analysis shows that: the height and width of accumulated sand-belt is the interaction of precipitation,distance to the sand source,leeward vegetation cover and annual average wind speed. Moreover,the height of accumulated sand-belts are negatively correlated to the soil moisture at the depth of 30- 50 cm,air humidity and leeward vegetation cover,and the width of the belts is also negatively correlated with the distance to the sand source. The ecological effects of the accumulated sand-belts are both positive( stopping sands from moving into farmland,protective role as an obstacle)and negative( when the belts decay and activate one day,they will become the new sand sources). At present,there are no signs showing the negative effects of the belts. The ecological effects of the accumulated sand-belts are: firstly the protective role as an obstacle,and secondly to intercept and reduce the sands moving into farmlands. 展开更多
关键词 Height of accumulated sand-belt Width of accumulated sand-belt Climatic and environmental factors canonical correlation factors Ecological effects Hexi of Gansu
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A CLASS OF COMPOUND VECTOR-VALUED PROBLEM AND FACTORIZATION OF MATRIX FUNCTION 被引量:2
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作者 郭国安 杜金元 《Acta Mathematica Scientia》 SCIE CSCD 2010年第1期173-179,共7页
In this article, we consider a class of compound vector-valued problem on upper-half plane C+, which consists of vector Riemann problem along a closed contour in C+ with matrix coefficient in H61der class and vector... In this article, we consider a class of compound vector-valued problem on upper-half plane C+, which consists of vector Riemann problem along a closed contour in C+ with matrix coefficient in H61der class and vector Hilbert problem on the real axis with essential bounded measurable matrix coefficient. Under appropriate assumption we obtain its solution by use of Corona theorem and factorization of matrix functions in decomposed Banach algebras. 展开更多
关键词 compound vector-valued problem Corona theorem canonical factorization Hardy space
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An algorithm and its application for obtaining some kind of infinite-dimensional Hamiltonian canonical formulation 被引量:6
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作者 任文秀 阿拉坦仓 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第11期3154-3160,共7页
Using factorization viewpoint of differential operator, this paper discusses how to transform a nonlinear evolution equation to infinite-dimensional Hamiltonian linear canonical formulation. It proves a sufficient con... Using factorization viewpoint of differential operator, this paper discusses how to transform a nonlinear evolution equation to infinite-dimensional Hamiltonian linear canonical formulation. It proves a sufficient condition of canonical factorization of operator, and provides a kind of mechanical algebraic method to achieve canonical 'σ/σx'-type expression, correspondingly. Then three examples are given, which show the application of the obtained algorithm. Thus a novel idea for inverse problem can be derived feasibly. 展开更多
关键词 nonlinear evolution equation infinite-dimensional Hamiltonian canonical system factorization of differential operator COMMUTATOR
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Relationships between Artemisia ordosica communities and environmental factors following sand-dune stabilization in the Mu Us desert,northwest China 被引量:3
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作者 Dongqing Fan Yuqing Zhang +1 位作者 Shugao Qin Bin Wu 《Journal of Forestry Research》 SCIE CAS CSCD 2017年第1期115-124,共10页
Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and ... Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and nutrient contents. However, the effects of factors on an A. ordosica community following sand stabilization remain unclear. In this study, we used canonical correspondence analysis (CCA) to examine the relationships between A. ordosica communities and environmental factors at three habitats: semi-fixed dune (SF), fixed dune with low-cov- erage biological soil crust (F), and fixed dune with high- coverage biological soil crust (FC) in Mu Us desert. The mean height and coverage of plants increased with sand stabilization, while species diversity and richness increased initially and then reduced significantly. Correlation analysis and CCA revealed that slope, soil organic carbon, and nutrient contents, proportion of fine soil particles, soil moisture, and thickness of biological soil crust were all highly correlated with vegetation characteristics. These environmental factors could explain 40.42 % of the vege- tation-environment relationships at the three habitats. The distribution of plant species was positively related to soil moisture in the SF dune. Soil moisture, soil nutrient, and fine-particle contents mainly affected plants distribution in the F dune. In the FC dune, distribution of plant species was positively and negatively correlated with the thickness of biological soil crust and soil moisture at a depth 0-20 cm, respectively. The dominance value of typical steppe species increased significantly following sand-dune stabilization and relations between species and samples in CCA ordination bi-plots showed that perennial grasses could invade the A. ordosica community on FC, indicating A. ordosica communities had a tendency to change into typical steppe vegetation with the further fixation. We conclude that the significant differentiation not only occurred in community characteristics, but also in the relationships between vegetation and environmental factors among the three stages of dune fixation. So, restoration of degraded dune ecosystems should be based on habitat conditions and ecological needs. 展开更多
关键词 Artemisia ordosica analysis Environmental factor stabilization canonical correspondence Mu Us desert Sand dune
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Wiener-Hopf Factorization of a Class of Matrix Functions and Corona Theorem 被引量:1
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作者 GUO Guoan DU Jinyuan 《Wuhan University Journal of Natural Sciences》 CAS 2009年第1期1-5,共5页
By using the Riemann-Hilbert method and the Corona theorem, Wiener-Hopf factorization for a class of matrix functions is studied. Under appropriate assumption, a sufficient and neces- sary condition for the existence ... By using the Riemann-Hilbert method and the Corona theorem, Wiener-Hopf factorization for a class of matrix functions is studied. Under appropriate assumption, a sufficient and neces- sary condition for the existence of the matrix function admitting canonical factorization is obtained and the solution to a class of non-linear Riemann-Hilbert problems is also given. Furthermore, by means of non-standard Corona theorem partial estimation of the general factorization can be obtained. 展开更多
关键词 Riemann-Hilbert problem Hardy space Corona theorem canonical factorization projector operator
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