A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical n...A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical non-equilibrium reactions encounters the stiffness problem, thus taking huge CPU time. Based on the domain decomposition method, a high efficient automatic domain decomposer for three-dimensional hybrid meshes is developed, and then implemented to the numerical simulation of hypersonic flows. Control equations are multicomponent N-S equations, and spatially discretized scheme is used by a cell-centered finite volume algorithm with a five-stage Runge-Kutta time step. The chemical kinetic model is a seven species model with weak ionization. A point-implicit method is used to solve the chemical source term. Numerical results on PC-Cluster are verified on a bi-ellipse model compared with references.展开更多
The surface properties of fluorite are often affected by dissolved gangue species(e.g.,calcite)during the flotation process.Microflotation testing with and without the addition of calcite supernatant was conducted usi...The surface properties of fluorite are often affected by dissolved gangue species(e.g.,calcite)during the flotation process.Microflotation testing with and without the addition of calcite supernatant was conducted using octanohydroxamic acid(OHA)as the collector.The results revealed that dissolved calcite species significantly affected the flotation behavior of fluorite.Fourier transform infrared spectra confirmed that the decrease in flotation recovery was linked to lower OHA adsorption.Solution chemistry analysis indicated that CaCO_(3) and Ca^(2+)from the calcite supernatant were the most favorably adsorbed species,and X-ray photoelectron spectroscopy analysis confirmed the surface adsorption of calcite species.Density functional theory simulations provided a detailed analysis of the multidentate adsorption configuration of OHA,which was the most favorable for adsorption on the fluorite surface.The adsorption energy calculation showed that the calcite dissolved species were more stably adsorbed on the fluorite surface than OHA.The pre-adsorption of calcite dissolved species hindered the adsorption of OHA due to electrostatic repulsion.展开更多
Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the ...Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the complicated bit allocation to match the different signal-to-noise-ratios(SNRs) of different sub-channels. In this paper,we propose a geometric mean decomposition(GMD)-based hybrid precoding to avoid the complicated bit allocation. Specifically,we seek a pair of analog and digital precoders sufficiently close to the unconstrained fully digital GMD precoder. To achieve this, we fix the analog precoder to design the digital precoder, and vice versa. The analog precoder is designed based on the orthogonal matching pursuit(OMP) algorithm, while GMD is used to obtain the digital precoder. Simulations show that the proposed GMD-based hybrid precoding achieves better performance than the conventional SVD-based hybrid precoding with only a slight increase in complexity.展开更多
In this paper, the authors propose a new model for active contours segmentation in a given image, based on Mumford-Shah functional (Mumford and Shah, 1989). The model is composed of a system of differential and integr...In this paper, the authors propose a new model for active contours segmentation in a given image, based on Mumford-Shah functional (Mumford and Shah, 1989). The model is composed of a system of differential and integral equations. By the experimental results we can keep the advantages of Chan and Vese's model (Chan and Vese, 2001 ) and avoid the regularization for Dirac function. More importantly, in theory we prove that the system has a unique viscosity solution.展开更多
文摘A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical non-equilibrium reactions encounters the stiffness problem, thus taking huge CPU time. Based on the domain decomposition method, a high efficient automatic domain decomposer for three-dimensional hybrid meshes is developed, and then implemented to the numerical simulation of hypersonic flows. Control equations are multicomponent N-S equations, and spatially discretized scheme is used by a cell-centered finite volume algorithm with a five-stage Runge-Kutta time step. The chemical kinetic model is a seven species model with weak ionization. A point-implicit method is used to solve the chemical source term. Numerical results on PC-Cluster are verified on a bi-ellipse model compared with references.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.51874247,51922091,51904249)Young Elite Scientists Sponsorship Program by CAST,China(No.2018QNRC001)+2 种基金Sichuan Science and Technology Program,China(Nos.2019YFS0453,2018JY0148)Open Research Fund of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,China(No.CNMRCUKF2001)Postgraduate Innovation Fund by Southwest University of Science and Technology,China(No.20ycx0027).
文摘The surface properties of fluorite are often affected by dissolved gangue species(e.g.,calcite)during the flotation process.Microflotation testing with and without the addition of calcite supernatant was conducted using octanohydroxamic acid(OHA)as the collector.The results revealed that dissolved calcite species significantly affected the flotation behavior of fluorite.Fourier transform infrared spectra confirmed that the decrease in flotation recovery was linked to lower OHA adsorption.Solution chemistry analysis indicated that CaCO_(3) and Ca^(2+)from the calcite supernatant were the most favorably adsorbed species,and X-ray photoelectron spectroscopy analysis confirmed the surface adsorption of calcite species.Density functional theory simulations provided a detailed analysis of the multidentate adsorption configuration of OHA,which was the most favorable for adsorption on the fluorite surface.The adsorption energy calculation showed that the calcite dissolved species were more stably adsorbed on the fluorite surface than OHA.The pre-adsorption of calcite dissolved species hindered the adsorption of OHA due to electrostatic repulsion.
基金supported by the National Natural Science Foundation of China for Outstanding Young Scholars (Grant No. 61722109)the National Natural Science Foundation of China (Grant No. 61571270)the Royal Academy of Engineering through the UK–China Industry Academia Partnership Programme Scheme (Grant No. UK-CIAPP\49)
文摘Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the complicated bit allocation to match the different signal-to-noise-ratios(SNRs) of different sub-channels. In this paper,we propose a geometric mean decomposition(GMD)-based hybrid precoding to avoid the complicated bit allocation. Specifically,we seek a pair of analog and digital precoders sufficiently close to the unconstrained fully digital GMD precoder. To achieve this, we fix the analog precoder to design the digital precoder, and vice versa. The analog precoder is designed based on the orthogonal matching pursuit(OMP) algorithm, while GMD is used to obtain the digital precoder. Simulations show that the proposed GMD-based hybrid precoding achieves better performance than the conventional SVD-based hybrid precoding with only a slight increase in complexity.
文摘In this paper, the authors propose a new model for active contours segmentation in a given image, based on Mumford-Shah functional (Mumford and Shah, 1989). The model is composed of a system of differential and integral equations. By the experimental results we can keep the advantages of Chan and Vese's model (Chan and Vese, 2001 ) and avoid the regularization for Dirac function. More importantly, in theory we prove that the system has a unique viscosity solution.
