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您的检索式：作者名="Bingchen Qian"
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| 1 | The Mechanism of Groundwater Salinization and Its Control in the Yaoba Oasis,Inner Mongolia显示文摘The arid area is one of the most concerned areas among the water resources researchers and economists. Northwest China will be an important developing region of China in the 21st century. Yaoba is a well-irrigation oasis within this arid area, which is located in the Alxa area west of the Helan Mountains and next to the Tengger desert in the east. It has contributed greatly to the local stock raising and agriculture since its development in 1970. However, the groundwater which the oasis depends on to survive has been getting salinized gradually and more serious in recent years.A comprehensive study was carried out using the methods of groundwater environment isotope analysis, lithofaci-es and palaeogeography, calculations of water-rock interaction and the existing form of chemical components in groundwater etc. It has been found that the salinization of groundwater is mainly caused by reinfiltration water solving the salt in soil which is deposited simultaneously with the sediments and accumulated in | WANG Bingchen QIU Hanxue XU Qian ZHENG Xilai LIU Guanqun | 2000 | Acta Geologica Sinica(English Edition)2000，74，2： | 1 |
| 2 | Inverse problems of the Erdos-Ko-Rado type theorems for families of vector spaces and permutations显示文摘Ever since the famous Erd os-Ko-Rado theorem initiated the study of intersecting families of subsets,extremal problems regarding intersecting properties of families of various combinatorial objects have been extensively investigated.Among them,studies about families of subsets,vector spaces and permutations are of particular concerns.Recently,we proposed a new quantitative intersection problem for families of subsets:For F([n]k),define its total intersection number as I(F)=ΣF1;F2∈F|F1∩F2|.Then,what is the structure of F when it has the maximal total intersection number among all the families in([n]k)with the same family size?In a recent paper,Kong and Ge(2020)studied this problem and characterized extremal structures of families maximizing the total intersection number of given sizes.In this paper,we consider the analogues of this problem for families of vector spaces and permutations.For certain ranges of family sizes,we provide structural characterizations for both families of subspaces and families of permutations having maximal total intersection numbers.To some extent,these results determine the unique structure of the optimal family for some certain values of jFj and characterize the relationship between having the maximal total intersection number and being intersecting.Besides,we also show several upper bounds on the total intersection numbers for both families of subspaces and families of permutations of given sizes. | Xiangliang Kong Yuanxiao Xi Bingchen Qian Gennian Ge | 2022 | Science China Mathematics2022，65，5： | 0 |
| 3 | DLSLA 3-D SAR imaging algorithm for off-grid targets based on pseudo-polar formatting and atomic norm minimization显示文摘This paper concerns the imaging problem for downward looking sparse linear array three-dimensional synthetic aperture radar(DLSLA 3-D SAR) under the circumstance of sparse and non-uniform cross-track dimensional virtual phase centers configuration. Since the 3-D imaging scene behaves typical sparsity in a certain domain, sparse recovery approaches hold the potential to achieve a better reconstruction performance. However,most of the existing compressive sensing(CS) algorithms assume the scatterers located on the pre-discretized grids, which is often violated by the off-grid effect. By contrast, atomic norm minimization(ANM) deals with sparse recovery problem directly on continuous space instead of discrete grids. This paper firstly analyzes the off-grid effect in DLSLA 3-D SAR sparse image reconstruction, and then introduces an imaging method applied to off-gird targets reconstruction which combines 3-D pseudo-polar formatting algorithm(pseudo-PFA) with ANM. With the proposed method, wave propagation and along-track image reconstruction are operated with pseudo-PFA, then the cross-track reconstruction is implemented with semidefinite programming(SDP) based on the ANM model. The proposed method holds the advantage of avoiding the off-grid effect and managing to locate the off-grid targets to accurate locations in different imaging scenes. The performance of the proposed method is verified and evaluated by the 3-D image reconstruction of different scenes, i.e., point targets and distributed scene. | Qian BAO Kuoye HAN Xueming PENG Wen HONG Bingchen ZHANG Weixian TAN | 2016 | Science China(Information Sciences)2016，59，6： | 0 |
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