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Search Results: 1 - 10 of 38711 matches for " Duan ZHOU "
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Dynamics of decadal changes in the distribution of double-cropping rice cultivation in China
JuQi Duan,GuangSheng Zhou
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-012-5608-y
Abstract: Quantitative description of changes in the distribution of paddy rice cultivation in response to recent climate change provides a reference for rice cultivation patterns and formulation of countermeasures to cope with future climate change in China. This study analyzes the dynamics of decadal changes in distribution of double-cropping rice in China during 1961–2010 in relation to climate change based on the maximum entropy method. Decadal changes in the double-cropping rice cultivation area and climatic suitability in China were apparent. The total area of climatically suitable regions was highest in the 1960s, and subsequently showed an increasing trend at first and then a decreasing trend from the 1970s to 2000s. However, the low climatic suitability area decreased, which implied that the moderate and high climatic suitability areas increased. Among the latter, the high climatic suitability area showed the highest increase in extent to 4.4 times that of the 1990s and four times that of the 1960s. The areas of double-cropping rice cultivation most sensitive to climate change are mainly located in central Jiangsu, central Anhui, the eastern Sichuan Basin, southern Henan and central Guizhou. Transformation of areas between low and moderate climatic suitability was observed in northern Zhejiang, southern Anhui and Hubei, and northern Guangxi. Transformation of areas between moderate and high climatic suitability was observed in central Jiangxi and Leizhou Peninsula. The northern boundary of double-cropping rice cultivation in China shifted southwards and contracted eastwards in the 1970s, and extended northwards in the 1980s. However, the northern boundary did not shift northwards in response to climate warming in the 2000s.
Non-linear forcing singular vector of a two-dimensional quasi-geostrophic model
Wansuo Duan,Feifan Zhou
Tellus A , 2013, DOI: 10.3402/tellusa.v65i0.18452
Abstract: We propose a non-linear forcing singular vector (NFSV) approach to infer the effect of non-linearity on the predictability associated with model errors. The NFSV is a generalisation of the forcing singular vector (FSV) to non-linear fields and acts as a tendency perturbation that results in a significantly large perturbation growth. In predictability studies, the NFSV, as a tendency error, may provide useful information about model errors that cause severe prediction uncertainties. In this article, a two-dimensional quasi-geostrophic (QG) model is used to study NFSVs and make a comparison between NFSVs and FSVs. We choose two basic flows: the first is a zonal steady flow (Ref-1), and the second is a meridional steady flow (Ref-2). The results demonstrate that the corresponding NFSVs contain a phase where the stream function tends to be contracted around regions of strong velocity shear. Furthermore, the NFSVs for the Ref-1 tend to have a meridional asymmetric spatial structure. Due to the absence of non-linearity, FSVs tend to have a larger spatial extension than NFSVs; in particular, the FSVs for the Ref-1 are almost symmetric in the stream function component. The prediction errors caused by FSVs in the non-linear QG model are generally smaller than those caused by FSVs in the linearised QG model; therefore, the non-linearity in the QG model would significantly saturate the perturbation growth. Nevertheless, the prediction errors caused by NFSVs (especially for the Ref-1) in the non-linear QG model are larger than those caused by FSVs, which further implies that the tendency errors of NFSV structures tend to reduce the damping effect of the non-linearity on the perturbation growth and are more applicable than those of FSV structures to describing the optimal mode of the model errors. The differences between NFSVs and FSVs demonstrate the usefulness of NFSVs in revealing the effects of non-linearity on predictability. The NFSV may be a useful non-linear technique for exploring the predictability problems introduced by model errors.
National Innovation-Oriented City Evaluation Study Based on Two-Stage DEA Model  [PDF]
Xianbiao Wei, Yuzhen Duan, Mo Wang, Junxing Zhou, Xiaobao Peng
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.59156
Abstract: The research on the evaluation indicator system of innovation-oriented cities has a long history. It presents different characteristics in different countries or regions. In 2006, China proposed the national strategy to build an innovation-oriented nation and subsequently approved more than 60 pilot cities in the country. The research on China’s innovation-oriented city assessment system is also increasing. On the basis of predecessors, this paper constructs innovation-oriented city evaluation indicator system with more links based on innovation link. It has three categories with 44 indicators in total according to input, intermediate output and final output. It creatively introduces in two-stage DEA model on sharing input and constructs the evaluation model based on the above evaluation indicator system. This paper makes an empirical analysis on the innovation-oriented cities in Yangtze River Delta including Hefei, arrives at innovation efficiency difference and puts forward some countermeasures and suggestions for the analysis results.
An explicit solution to right factorization with application in eigenstructure assignment

Guangren DUAN,Bin ZHOU,

控制理论与应用 , 2005,
Abstract: Based on the well-known Leverrier algorithm, a simple explicit solution to right factorization of a linear system is established.This solution is expressed by the controllability matrix of the given system and a symmetric operator matrix.Applications of this solution to a type of generalized Sylvester matrix equations and the problem of parametric eigenstructure assignment by state feedback are investigated,and general complete parametric solutions to these two problems are deduced. These new solutions are simple,and possess desirable structural properties which render the solutions readily implementable.An example demonstrates the effect of the proposed results.
An explicit solution to polynomial matrix right coprime factorization with application in eigenstructure assignment

Bin ZHOU,Guangren DUAN,

控制理论与应用 , 2006,
Abstract: In this paper, an explicit solution to polynomial matrix right coprime factorization of input-state transfer function is obtained in terms of the Krylov matrix and the Pseudo-controllability indices of the pair of coefficient matrices. The proposed approach only needs to solve a series of linear equations. Applications of this solution to a type of generalized Sylvester matrix equations and the problem of parametric eigenstructure assignment by state feedback are investigated. These new solutions are simple, they possess better structural properties and are very convenient to use. An example shows the effect of the proposed results.
Solutions to the generalized Sylvester matrix equations by a singular value decomposition

Bin ZHOU,Guangren DUAN,

控制理论与应用 , 2007,
Solution of Nonlinear Elliptic Boundary Value Problemsand Its Iterative Construction
Li Wei,Liling Duan,Haiyun Zhou
Abstract and Applied Analysis , 2012, DOI: 10.1155/2012/210325
Abstract: We study a kind of nonlinear elliptic boundary value problems with generalized-Laplacian operator. The unique solution is proved to be existing and the relationship between thissolution and the zero point of a suitably defined nonlinear maximal monotone operator is investigated. Moreover, an iterative scheme is constructed to be strongly convergent to the unique solution. Thework done in this paper is meaningful since it combines the knowledge of ranges for nonlinear operators,zero point of nonlinear operators, iterative schemes, and boundary value problems together. Some newtechniques of constructing appropriate operators and decomposing the equations are employed, whichextend and complement some of the previous work.
Infrared Optical Response of Metallic Graphene Nanoribbons
Zigang Duan,Wenhu Liao,Guanghui Zhou
Advances in Condensed Matter Physics , 2010, DOI: 10.1155/2010/258019
Abstract: We investigate theoretically the infrared optical response characteristics of metallic armchair/zigzag-edge graphene nanoribbons (A/ZGNRs) to an external longitudinally polarized electromagnetic field at low temperatures. Within the framework of linear response theory at the perturbation regime, we examine the optical infrared absorption threshold energy, absorption power, dielectric function, and electron energy loss spectra near the neutrality points of the systems. It is demonstrated that, by some numerical examples, the photon-assisted direct interband absorptions for AGNR exist with different selection rules from those for ZGNR and single-walled carbon nanotube at infrared regime. This infrared optical property dependence of GNRs on field frequency may be used to design graphene-based nanoscale optoelectronic devices for the detection of infrared electromagnetic irradiations. 1. Introduction Intriguing experimental [1] and theoretical [2–11] attentions have been paid to graphene-based electronics, especially the unique electronic [3–11] and transport properties [12–19] of GNRs due to its potential applications in nanodevices. The optical spectra [20] of semiconducting GNRs and the excitonic effects [21, 22] in the optical properties of AGNRs with many-electron effects included have been investigated by density functional theory and the first-principles calculations, respectively. Liu et al. [23] have demonstrated that magnetic field can enhance and tune the optical response of GNRs in the terahertz to far-infrared regime. The effects of intrinsic spin-orbit and Coulomb interactions on low-energy properties of AGNRs have been studied [24]. The optical absorption selection rule [25] for ZGNR has been proposed to be qualitatively different from that for armchair carbon nonotubes (CNTs) [26, 27]. The optical properties of AGNRs [28] irradiated under an longitudinal polarized electromagnetic field have also been analyzed. Zhang et al. [29] have investigated the magneto-optical properties of graphene quantum dots. Furthermore, the optical response of the ZGNRs with the spin interaction included has been found to be dominated by magnetic edge-state-derived excitons other than the affections of the edges and confinement on the optical transition energies. [30, 31] However, to the best of our acknowledge, the optical properties for driven GNRs [20–25, 28–31] in the important frequency band of infrared have seldom been involved. A -AGNR is either semiconducting or metallic depending on the number of dimer lines along the edge. However, an -ZGNR is always
Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data
MeiRong Wang,ShunWu Zhou,AnMin Duan
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4838-8
Abstract: The trend in the atmospheric heat source over the central and eastern Tibetan Plateau (CE-TP) is quantitatively estimated using historical observations at 71 meteorological stations, three reanalysis datasets from 1980–2008, and two satellite radiation datasets from 1984–2007. Results show that a weakening of sensible heat (SH) flux over the CE-TP continues. The most significant trend occurs in spring, induced mainly by decelerated surface wind speeds. The ground-air temperature difference shows a notable increasing trend over the last 5 years. Trends in net radiation flux of the atmospheric column over the CE-TP, evaluated by two satellite radiation datasets, are clearly different. Trends in the atmospheric heat source calculated by the three reanalysis datasets are not completely consistent, and even show opposite signals. Results from the two datasets both show a weakening of the heat source but the magnitude of one is significantly stronger, whereas an increase is indicated by the other data. Therefore, it is challenging to accurately calculate the trend in the atmospheric heat source over the CE-TP, particularly from the estimates of the reanalysis datasets.
Closed-form solutions to the matrix equation AX ? EXF = BY with F in companion form

Bin Zhou,Guang-Ren Duan,

国际自动化与计算杂志 , 2009,
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