Awell-anticipated wide-field X-ray focusing imager,the Einstein Probe(EP,also named“Tianguan”in Chinese)has caught the eye of astronomers since its launch in January 2024.Initiated and sponsored by the Chinese Acade...Awell-anticipated wide-field X-ray focusing imager,the Einstein Probe(EP,also named“Tianguan”in Chinese)has caught the eye of astronomers since its launch in January 2024.Initiated and sponsored by the Chinese Academy of Sciences(CAS),and developed in cooperation with the European Space Agency(ESA).展开更多
动床阻力研究是河流动力学中的重要课题,在回顾河流动床阻力研究现状的基础上,剖析了Einstein H A(以下简称Einstein)河流动床阻力公式存在的问题;一是原经验曲线未涵盖高能态区范围;二是试算的黄河沙粒水力半径约30%大于实测水深,导致...动床阻力研究是河流动力学中的重要课题,在回顾河流动床阻力研究现状的基础上,剖析了Einstein H A(以下简称Einstein)河流动床阻力公式存在的问题;一是原经验曲线未涵盖高能态区范围;二是试算的黄河沙粒水力半径约30%大于实测水深,导致按水力半径分割定义式求出的沙波水力半径为负值的物理悖论。通过黄河实测数据补充点群范围,外延曲线且拟合出关系式。利用实测资料计算分析Einstein动床阻力公式适用性,表明国外河流沙波水力半径未出现负值且水力参数大于0.3时适用,适当修正初步适用于黄河下游。引入张红武河床纵向稳定指标关系式求河床比降替代实测水面比降,在降低沙波水力半径负值率的前提下提高了公式验证精度,表明Einstein河流动床阻力公式经过修正后,适用于黄河下游相关计算。展开更多
In this paper,we define the spectral Einstein functional associated with the Dirac operator for manifolds with boundary.And we give the proof of Kastler-Kalau-Walze type theorem for the spectral Einstein functional as...In this paper,we define the spectral Einstein functional associated with the Dirac operator for manifolds with boundary.And we give the proof of Kastler-Kalau-Walze type theorem for the spectral Einstein functional associated with the Dirac operator on 4-dimensional manifolds with boundary.展开更多
We consider two pointlike static impurities without direct interaction immersed in a three-dimensional Bose–Einstein condensate(BEC)at zero temperature.By solving the Gross–Pitaevskii(GP)equation in a perturbative m...We consider two pointlike static impurities without direct interaction immersed in a three-dimensional Bose–Einstein condensate(BEC)at zero temperature.By solving the Gross–Pitaevskii(GP)equation in a perturbative manner,we calculate the ground state energy in the region where the atom–impurity interaction is assumed to be weak.We obtain an analytical expression for the spatial distribution of atom number density and the effective force between these two impurities.The effective force is found to be closely related to the strength of the atom–impurity interaction and the relative distance between these two impurities.Two critical relative distances are found between the two impurities.The first one corresponds to the vanishing of the perturbed energy with impurities,although the effective force between the two impurities still exists.At the second critical value,the energy of the impurities changes linearly with the atom–impurity interaction;otherwise,it changes quadratically with the atom–impurity interaction.展开更多
In this paper,we study scalar curvature rigidity of non-smooth metrics on smooth manifolds with non-positive Yamabe invariant.We prove that if the scalar curvature is not less than the Yamabe invariant in the distribu...In this paper,we study scalar curvature rigidity of non-smooth metrics on smooth manifolds with non-positive Yamabe invariant.We prove that if the scalar curvature is not less than the Yamabe invariant in the distributional sense,then the manifold must be isometric to an Einstein manifold.This result extends Theorem 1.4 in Jiang,Sheng and Zhang[27],from a special case where the manifolds have zero Yamabe invariant to general cases where the manifolds have non-positive Yamabe invariant.展开更多
A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature As...A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature Astronomy on January 23,2025 their discovery of an X-ray flash about 12.5 billion lightyears away.The signals burst out only 1.2 billion years after the Big Bang,when our 13.8-billion-year-old universe was still in its infancy,and a science satellite swiftly recorded them.展开更多
The Stokes–Einstein–Debye(SED) relation in TIP5P water is tested with the original formula and its variants within the temperature range 240–390 K. The results indicate that although the variants explicitly break d...The Stokes–Einstein–Debye(SED) relation in TIP5P water is tested with the original formula and its variants within the temperature range 240–390 K. The results indicate that although the variants explicitly break down, the original SED relation is almost valid. Compared with the Stokes–Einstein relation, no explicit decoupling is observed in translational and rotational motion. Variation of the effective hydrodynamic radius is critical to testing the validity of the SED relation.展开更多
In this paper,we give the definitions of the non-self-adjoint spectral triple and its spectral Einstein functional.We compute the spectral Einstein functional associated with the nonminimal de Rham-Hodge operator on e...In this paper,we give the definitions of the non-self-adjoint spectral triple and its spectral Einstein functional.We compute the spectral Einstein functional associated with the nonminimal de Rham-Hodge operator on evendimensional compact manifolds without boundary.Finally,several examples of the non-self-adjoint spectral triple are listed.展开更多
We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the st...We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.展开更多
文摘Awell-anticipated wide-field X-ray focusing imager,the Einstein Probe(EP,also named“Tianguan”in Chinese)has caught the eye of astronomers since its launch in January 2024.Initiated and sponsored by the Chinese Academy of Sciences(CAS),and developed in cooperation with the European Space Agency(ESA).
文摘动床阻力研究是河流动力学中的重要课题,在回顾河流动床阻力研究现状的基础上,剖析了Einstein H A(以下简称Einstein)河流动床阻力公式存在的问题;一是原经验曲线未涵盖高能态区范围;二是试算的黄河沙粒水力半径约30%大于实测水深,导致按水力半径分割定义式求出的沙波水力半径为负值的物理悖论。通过黄河实测数据补充点群范围,外延曲线且拟合出关系式。利用实测资料计算分析Einstein动床阻力公式适用性,表明国外河流沙波水力半径未出现负值且水力参数大于0.3时适用,适当修正初步适用于黄河下游。引入张红武河床纵向稳定指标关系式求河床比降替代实测水面比降,在降低沙波水力半径负值率的前提下提高了公式验证精度,表明Einstein河流动床阻力公式经过修正后,适用于黄河下游相关计算。
文摘In this paper,we define the spectral Einstein functional associated with the Dirac operator for manifolds with boundary.And we give the proof of Kastler-Kalau-Walze type theorem for the spectral Einstein functional associated with the Dirac operator on 4-dimensional manifolds with boundary.
基金funding from the National Natural Science Foundation of China(Grant Nos.12174055 and 11674058)the Natural Science Foundation of Fujian(Grant No.2020J01195)funding from the National Natural Science Foundation of China(Grant No.12175027)。
文摘We consider two pointlike static impurities without direct interaction immersed in a three-dimensional Bose–Einstein condensate(BEC)at zero temperature.By solving the Gross–Pitaevskii(GP)equation in a perturbative manner,we calculate the ground state energy in the region where the atom–impurity interaction is assumed to be weak.We obtain an analytical expression for the spatial distribution of atom number density and the effective force between these two impurities.The effective force is found to be closely related to the strength of the atom–impurity interaction and the relative distance between these two impurities.Two critical relative distances are found between the two impurities.The first one corresponds to the vanishing of the perturbed energy with impurities,although the effective force between the two impurities still exists.At the second critical value,the energy of the impurities changes linearly with the atom–impurity interaction;otherwise,it changes quadratically with the atom–impurity interaction.
基金Supported by the National Key Research and Development Program of China(2022YFA1005501)the Natural Science Foundation of Jiangsu Province(BK20241433).
文摘In this paper,we study scalar curvature rigidity of non-smooth metrics on smooth manifolds with non-positive Yamabe invariant.We prove that if the scalar curvature is not less than the Yamabe invariant in the distributional sense,then the manifold must be isometric to an Einstein manifold.This result extends Theorem 1.4 in Jiang,Sheng and Zhang[27],from a special case where the manifolds have zero Yamabe invariant to general cases where the manifolds have non-positive Yamabe invariant.
文摘A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature Astronomy on January 23,2025 their discovery of an X-ray flash about 12.5 billion lightyears away.The signals burst out only 1.2 billion years after the Big Bang,when our 13.8-billion-year-old universe was still in its infancy,and a science satellite swiftly recorded them.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12104502)the Natural Science Foundation of Sichuan Province (Grant No. 2023YFG0308)the Fundamental Research Funds for the Central Universities (Grant No. 24CAFUC03057)。
文摘The Stokes–Einstein–Debye(SED) relation in TIP5P water is tested with the original formula and its variants within the temperature range 240–390 K. The results indicate that although the variants explicitly break down, the original SED relation is almost valid. Compared with the Stokes–Einstein relation, no explicit decoupling is observed in translational and rotational motion. Variation of the effective hydrodynamic radius is critical to testing the validity of the SED relation.
基金supported by the National Natural Science Foundation of China(Grant No.11771070).
文摘In this paper,we give the definitions of the non-self-adjoint spectral triple and its spectral Einstein functional.We compute the spectral Einstein functional associated with the nonminimal de Rham-Hodge operator on evendimensional compact manifolds without boundary.Finally,several examples of the non-self-adjoint spectral triple are listed.
基金supported by the National Natural Science Foundation of China(Grant No.62275075)the Natural Science Foundation of Hubei Soliton Research Association(Grant No.2025HBSRA09)+1 种基金joint supported by Hubei Provincial Natural Science Foundation and Xianning of China(Grant Nos.2025AFD401 and 2025AFD405)Israel Science Foundation(Grant No.1695/22).
文摘We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.
