目前大多数交直流混联系统无功优化计算方法还无法考虑直流输电功率调节次数限制,影响了无功优化计算的实际应用。将计及直流功率日调节次数限制的交直流系统无功优化问题的求解分解为96个时间断面的连续无功优化计算、直流输电功率曲...目前大多数交直流混联系统无功优化计算方法还无法考虑直流输电功率调节次数限制,影响了无功优化计算的实际应用。将计及直流功率日调节次数限制的交直流系统无功优化问题的求解分解为96个时间断面的连续无功优化计算、直流输电功率曲线的阶梯化和在确定各个时段直流输电功率情况下的连续无功优化计算3个阶段,较好地解决了交直流混联系统无功优化计算工程化问题。最后用南方电网500 k V主网架系统数据进行了测试,验证了该算法的合理性。并分析了不同直流功率日最大调节次数取值对无功优化计算的影响。展开更多
Using Ablowitz-Ramani Segur algorithm, the coupled KdV systems are reclassified under the Painlevé integrable sense while the similarity reductions of the model are obtained by using the Clarkson and Kruskal＇s d...Using Ablowitz-Ramani Segur algorithm, the coupled KdV systems are reclassified under the Painlevé integrable sense while the similarity reductions of the model are obtained by using the Clarkson and Kruskal＇s direct method. Some new types of Painlevé integrable models including a model with different dispersion relations for two layer fluids are found.展开更多
We study the quantum phase transition of ultracold atoms in the honeycomb optical lattice. The Hamiltonian of ultracold bosonic atoms in the honeycomb optical lattice is derived. We take the mean-field approximation a...We study the quantum phase transition of ultracold atoms in the honeycomb optical lattice. The Hamiltonian of ultracold bosonic atoms in the honeycomb optical lattice is derived. We take the mean-field approximation and further solve the Hamiltonian with the numerical diagonalization method. We obtain the phase diagram and find that the Mort-insulator （MI）, density wave （DW） and modulated superfluid （MS） phases appear. Furthermore, the phase diagram is analyzed according to the order parameter and the average number of particles.展开更多
Thomas-Fermi theory is an approximate method, which is widely used to describe the properties of matter at various hierarchical levels （atomic nucleus, atom, molecule, solid, etc.）. Special development is achieved u...Thomas-Fermi theory is an approximate method, which is widely used to describe the properties of matter at various hierarchical levels （atomic nucleus, atom, molecule, solid, etc.）. Special development is achieved using Thomas-Fermi theory to the theory of extreme states of matter appearing under high pressures, high temperatures or strong external fields. Relevant sections of physics and related sciences （astrophysics, quantum chemistry, a number of applied sciences） determine the scope of Thomas-Fermi theory. Popularity Thomas-Fermi theory is related to its relative simplicity, clarity and versatility. The latter means that result of the calculation by Thomas-Fermi theory applies immediately to all chemical elements： the transition from element to element is as simple scale transformation. These features make it highly convenient tool for qualitative and, in many cases, quantitative analysis.展开更多
Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of react...Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of reaction,activation barriers,and rate constants.Understanding of density functional exchangecorrelation approximations is essential to reveal the mechanism and performance of a catalyst.In the present work,we reported the influence of six exchange-correlation density functionals,including PBE,RPBE,BEEF+vdW,optB86b+vdW,SCAN,and SCAN+rVV10,on the adsorption energies,reaction energies and activation barriers of carbon hydrogenation and carbon-carbon couplings during the formation of methane and ethane over Ru(0001)and Ru(1011)surfaces.We found the calculated reaction energies are strongly dependent on exchange-correlation density functionals due to the difference in coordination number between reactants and products on surfaces.The deviation of the calculated elementary reaction energies can be accumulated to a large value for chemical reaction involving multiple steps and vary considerably with different exchange-correlation density functionals calculations.The different exchange-correlation density functionals are found to influence considerably the selectivity of Ru(0001)surface for methane,ethylene,and ethane formation determined by the adsorption energies of intermediates involved.However,the influence on the barriers of the elementary surface reactions and the structural sensitivity of Ru(0001)and Ru(1011)are modest.Our work highlights the limitation of exchange-correlation density functionals on computational catalysis and the importance of choosing a proper exchange-correlation density functional in correctly evaluating the activity and selectivity of a catalyst.展开更多
The Effects of pressure stress work and viscous dissipation in mixed convection flow along a vertical fiat plate have been investigated. The results are obtained by transforming the governing system of boundary layer ...The Effects of pressure stress work and viscous dissipation in mixed convection flow along a vertical fiat plate have been investigated. The results are obtained by transforming the governing system of boundary layer equations into a system of non-dimensional equations and by applying implicit finite difference method together with Newton＇s linearization approximation. Numerical results for different values of pressure stress work parameter, viscous dissipation parameter and Prandtl number have been obtained. The velocity profiles, temperature distributions, skin friction co-efficient and the rate of heat transfer have been presented graphically for the effects of the aforementioned parameters.展开更多
文摘目前大多数交直流混联系统无功优化计算方法还无法考虑直流输电功率调节次数限制,影响了无功优化计算的实际应用。将计及直流功率日调节次数限制的交直流系统无功优化问题的求解分解为96个时间断面的连续无功优化计算、直流输电功率曲线的阶梯化和在确定各个时段直流输电功率情况下的连续无功优化计算3个阶段,较好地解决了交直流混联系统无功优化计算工程化问题。最后用南方电网500 k V主网架系统数据进行了测试,验证了该算法的合理性。并分析了不同直流功率日最大调节次数取值对无功优化计算的影响。
基金National Natural Science Foundations of China under Grant Nos.10475055 and 40305009
文摘Using Ablowitz-Ramani Segur algorithm, the coupled KdV systems are reclassified under the Painlevé integrable sense while the similarity reductions of the model are obtained by using the Clarkson and Kruskal＇s direct method. Some new types of Painlevé integrable models including a model with different dispersion relations for two layer fluids are found.
基金Supported by the Teaching and Research Foundation for the Outstanding Young Faculty of Southeast University
文摘We study the quantum phase transition of ultracold atoms in the honeycomb optical lattice. The Hamiltonian of ultracold bosonic atoms in the honeycomb optical lattice is derived. We take the mean-field approximation and further solve the Hamiltonian with the numerical diagonalization method. We obtain the phase diagram and find that the Mort-insulator （MI）, density wave （DW） and modulated superfluid （MS） phases appear. Furthermore, the phase diagram is analyzed according to the order parameter and the average number of particles.
文摘Thomas-Fermi theory is an approximate method, which is widely used to describe the properties of matter at various hierarchical levels （atomic nucleus, atom, molecule, solid, etc.）. Special development is achieved using Thomas-Fermi theory to the theory of extreme states of matter appearing under high pressures, high temperatures or strong external fields. Relevant sections of physics and related sciences （astrophysics, quantum chemistry, a number of applied sciences） determine the scope of Thomas-Fermi theory. Popularity Thomas-Fermi theory is related to its relative simplicity, clarity and versatility. The latter means that result of the calculation by Thomas-Fermi theory applies immediately to all chemical elements： the transition from element to element is as simple scale transformation. These features make it highly convenient tool for qualitative and, in many cases, quantitative analysis.
基金This work was supported by the Key Technologies R&D Program of China(No.2018YFA0208603)the National Natural Science Foundation of China(No.22172150 and No.91945302)+5 种基金the Chinese Academy of Sciences Key Project(QYZDJ-SSW-SLH054)the Start-up Funds of University of Science and Technology of China(No.KY2060000171)the National Natural Science Foundation of Anhui province(No.2108085QB62)USTC Research Funds of the Double First-Class Initiative(No.YD2060002012)K.C.Wong Education(No.GJTD-2020-15)highPerformance Computational Resources provided by the University of Science and Technology of China(http://scc.ustc.edu.cn)and Hefei Advanced Computing center.
文摘Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of reaction,activation barriers,and rate constants.Understanding of density functional exchangecorrelation approximations is essential to reveal the mechanism and performance of a catalyst.In the present work,we reported the influence of six exchange-correlation density functionals,including PBE,RPBE,BEEF+vdW,optB86b+vdW,SCAN,and SCAN+rVV10,on the adsorption energies,reaction energies and activation barriers of carbon hydrogenation and carbon-carbon couplings during the formation of methane and ethane over Ru(0001)and Ru(1011)surfaces.We found the calculated reaction energies are strongly dependent on exchange-correlation density functionals due to the difference in coordination number between reactants and products on surfaces.The deviation of the calculated elementary reaction energies can be accumulated to a large value for chemical reaction involving multiple steps and vary considerably with different exchange-correlation density functionals calculations.The different exchange-correlation density functionals are found to influence considerably the selectivity of Ru(0001)surface for methane,ethylene,and ethane formation determined by the adsorption energies of intermediates involved.However,the influence on the barriers of the elementary surface reactions and the structural sensitivity of Ru(0001)and Ru(1011)are modest.Our work highlights the limitation of exchange-correlation density functionals on computational catalysis and the importance of choosing a proper exchange-correlation density functional in correctly evaluating the activity and selectivity of a catalyst.
文摘The Effects of pressure stress work and viscous dissipation in mixed convection flow along a vertical fiat plate have been investigated. The results are obtained by transforming the governing system of boundary layer equations into a system of non-dimensional equations and by applying implicit finite difference method together with Newton＇s linearization approximation. Numerical results for different values of pressure stress work parameter, viscous dissipation parameter and Prandtl number have been obtained. The velocity profiles, temperature distributions, skin friction co-efficient and the rate of heat transfer have been presented graphically for the effects of the aforementioned parameters.
