The paper focuses on developing and studying efficient block preconditioners based on classical algebraic multigrid for the large-scale sparse linear systems arising from the fully coupled and implicitly cell-centered...
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We consider computing the minimal nonnegative solution of the nonsymmetric algebraic Riccati equation with *** is well known that such equations can be efficiently solved via the structure-preserving doubling algorith...
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We consider computing the minimal nonnegative solution of the nonsymmetric algebraic Riccati equation with *** is well known that such equations can be efficiently solved via the structure-preserving doubling algorithm(SDA)with the shift-and-shrink transformation or the generalized Cayley *** this paper,we propose a more generalized transformation of which the shift-and-shrink transformation and the generalized Cayley transformation could be viewed as two special ***,the doubling algorithm based on the proposed generalized transformation is presented and shown to be ***,the convergence result and the comparison theorem on convergent rate are *** numerical experiments show that the doubling algorithm with the generalized transformation is efficient to derive the minimal nonnegative solution of nonsymmetric algebraic Riccati equation with M-matrix.
In recent years, supervised learning has been widely used in various tasks of optical remote sensing image understanding, including remote sensing image classification, pixel-wise segmentation, change detection, and o...
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When common factors strongly influence two cross-correlated time series recorded in complex natural and social systems, the results will be biased if we use multifractal detrended cross-correlation analysis (MF-DXA) w...
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When common factors strongly influence two cross-correlated time series recorded in complex natural and social systems, the results will be biased if we use multifractal detrended cross-correlation analysis (MF-DXA) without considering these common factors. In order to better study the time series of such cases, we extend the multifractal temporally weighted detrended cross-correlation analysis (MF-TWXDFA) proposed by our group (Wei et al., 2017) and propose multifractal temporally weighted detrended partial cross-correlation analysis (MF-TWDPCCA) to quantify intrinsic power-law cross-correlation of two non-stationary time series affected by common external factors in this paper. To test the performance of MF-TWDPCCA, we apply it and multifractal partial cross-correlation analysis (MF-DPXA) proposed by Qian et al. (2015) on simulated series. Numerical tests on artificially simulated series demonstrate that MF-TWDPCCA can more accurately detect the intrinsic cross-correlations for two simultaneously recorded series than MF-DPXA and MF-TWXDFA. To further show the utility of MF-TWDPCCA, we apply it on time series from stock markets and find that there exists significantly multifractal power-law cross-correlation between stock returns. In addition, a new partial cross-correlation coefficient is defined to quantify the level of intrinsic cross-correlation between two time series.
Dirac point plays a crucial role in regulating electronic properties of topological semimetals. In two dimensions, the manipulation of Dirac points can spur a transition from Dirac semimetal through semi-Dirac phase t...
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Dirac point plays a crucial role in regulating electronic properties of topological semimetals. In two dimensions, the manipulation of Dirac points can spur a transition from Dirac semimetal through semi-Dirac phase to a gapped phase. Across such a so-called Lifshitz transition, we find that the quantum interference corrections to the conductivity δσxx and δσyy are always negative, giving rise to a weak localization behavior. The ratio δσxx/δσyy undergoes a transition from linear to parabolic dependence on the merging parameter across the Lifshitz transition, which leads to a crossover of the temperature dependence of the inverse inelastic scattering time 1/τɛ from ∼T to ∼Tln(T0/T). This fingerprint behavior can be readily tested experimentally through merging Dirac points in two-dimensional lattices. This work presents an alternative perspective to understand weak localization through Lifshitz transition.
Ferrofluid is a colloidal suspension system with magnetic nanoparticles, the overall field of study in ferrofluid has a highly interdisciplinary character in practical applications. In this paper a set of parabolized ...
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Ferrofluid is a colloidal suspension system with magnetic nanoparticles, the overall field of study in ferrofluid has a highly interdisciplinary character in practical applications. In this paper a set of parabolized stability equations(PSEs)of ferrofluid is represented by Rosensweig equations. The characteristic analysis show that in subsonic region the nonlinear PSEs of ferrofluid are parabolical, and in supersonic region are elliptical. The PSEs of ferrofluid is solved numerically for heat conduction process and RT instability problem, respectively. The results of characteristic analysis and numerical simulation all verify that the basic characteristic of ferrofluid are not influenced by the external magnetic field, and the viscosity is the only reason for the variation of ellipticity of PSEs of ferrofluid. That is to say, the external magnetic field and the viscosity are essentially different.
Inspired by dynamic programming, we propose Stochastic Virtual Gradient Descent (SVGD) algorithm where the Virtual Gradient is defined by computational graph and automatic differentiation. The method is computationall...
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Ions in the bulk of solvent-free ionic liquids bind into ion pairs and *** competition between the propensity of ions to stay in a bound state,and the reduction of the energy when unbinding in electric field,determine...
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Ions in the bulk of solvent-free ionic liquids bind into ion pairs and *** competition between the propensity of ions to stay in a bound state,and the reduction of the energy when unbinding in electric field,determines the portion of free ions in the electrical double *** present the simplest possible mean-field theory to study this effect."Cracking"of ion pairs into free ions in electric field is accompanied by the change of the dielectric response of the ionic *** predictions from the theory are verified and further explored by molecular dynamics simulations.A particular finding of the theory is that the differential capacitance vs potential curve displays a bell shape,despite the low concentration of free charge carriers,because the dielectric response reduces the threshold concentration for the bell-to camelshape *** presented theory does not take into account overscreening and oscillating charge distributions in the electrical double *** in spite of the simplicity of the model,its findings demonstrate a clear physical effect:a preference to be a charged monopole rather than a dipole(or higher order multipole)in strong electric field.
Based on the first-principles calculations, we demonstrated that a GeSe/SnSe heterostructure has type-II band alignment and a direct band gap, which can effectively prevent the recombination of photogenerated electron...
Based on the first-principles calculations, we demonstrated that a GeSe/SnSe heterostructure has type-II band alignment and a direct band gap, which can effectively prevent the recombination of photogenerated electron–hole pairs. Moreover, the GeSe/SnSe heterostructure also exhibits strong optical absorption intensity, which can reach the order of 105 cm−1. Our predicted photoelectric conversion efficiency (PCE) for the GeSe/SnSe heterostructure reaches 21.47%. We also found that the hole carrier mobility of the GeSe/SnSe heterostructure along the x direction has been significantly improved to 6.42 × 104 cm2 V−1 s−1, which is higher than that of black phosphorus (1 × 104 cm2 V−1 s−1). By applying a vertical external electric field, we found that the band gap and band offset of the GeSe/SnSe heterojunction can be effectively tuned. The revealed type-II band alignment, strong optical absorption, superior PCE and superior hole carrier mobility of the GeSe/SnSe heterostructure imply that this new proposed material has broad application prospects in solar cells.
Land use projections are crucial for climate models to forecast the impacts of land use changes on the Earth’s ***,the spatial resolution of existing global land use projections(e.g.,0.25°×0.25°in the ...
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Land use projections are crucial for climate models to forecast the impacts of land use changes on the Earth’s ***,the spatial resolution of existing global land use projections(e.g.,0.25°×0.25°in the Land-Use Harmonization(LUH2)datasets)is still too coarse to drive regional climate models and assess mitigation effectiveness at regional and local *** generate a high-resolution land use product with the newest integrated scenarios of the shared socioeconomic pathways and the representative concentration pathways(SSPs-RCPs)for various regional climate studies in China,here we first conduct land use simulations with a newly developed Future Land Uses simulation(FLUS)model based on the trajectories of land use demands extracted from the LUH2 *** this basis,a new set of land use projections under the plant functional type(PFT)classification,with a temporal resolution of 5 years and a spatial resolution of 5 km,in eight SSP-RCP scenarios from 2015 to 2100 in China is *** results show that differences in land use dynamics under different SSP-RCP scenarios are jointly affected by global assumptions and national ***,with improved spatial resolution,the data produced in this study can sufficiently describe the details of land use distribution and better capture the spatial heterogeneity of different land use types at the regional *** highlight that these new land use projections at the PFT level have a strong potential for reducing uncertainty in the simulation of regional climate models with finer spatial resolutions.
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