We investigate the boundary effect of quark–gluon plasma(QGP)droplets and the self-similarity effect of hadrons on QGP–hadron phase transition.In intermediate-or low-energy collisions,when the transverse momentum is...We investigate the boundary effect of quark–gluon plasma(QGP)droplets and the self-similarity effect of hadrons on QGP–hadron phase transition.In intermediate-or low-energy collisions,when the transverse momentum is below quantum chromodynamics(QCD)scale,QGP cannot be produced.However,if the transverse momentum changes to a relatively large value,a smallscale QGP droplet is produced.The modified MIT bag model with the multiple reflection expansion method is employed to study the QGP droplet with the curved boundary effect.It is found that the energy density,entropy density and pressure of QGP with the influence are smaller than those without the influence.In the hadron phase,we propose the two-body fractal model(TBFM)to study the self-similarity structure,arising from resonance,quantum correlation and interaction effects.It is observed that the energy density,entropy density and pressure increase due to the self-similarity structure.We calculate the transverse momentum spectra of pions with the self-similarity structure influence,which show good agreement with experimental data.Considering both boundary effect and self-similarity structure influence,our model predicts an increase in the transition temperature compared to the scenarios without these two effects in the High Intensity heavy-ion Accelerator Facility(HIAF)energy region,2.2 GeV to approximately 4.5 GeV.展开更多
The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices...The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices. In this work, we propose the concept of a Lieb electride, where the non-bound electrons gather at the middle edges,behaving as the quasi-atoms of a Lieb lattice, enabling the emergence of flat bands. Using crystal structure prediction method MAGUS and first-principles calculations, we predict a stable candidate, Ca_(2)I, at ambient pressure. Distinct from conventional electrides with localized electrons at cavity centers, Ca_(2)I features interstitial electrons situated at cavity edges. The resultant flat bands lie close to the Fermi level, giving rise to a pronounced peak in the density of states and leading to Stoner-type ferromagnetism. With increasing pressures, we observe quantum phase transitions from ferromagnetic to non-magnetic and finally to antiferromagnetic orders in Ca_(2)I.Intriguingly, superconductivity emerges in the antiferromagnetic region, suggesting potential competition between these correlated states. Our study not only extends the concepts of electrides but also provides a novel strategy for realizing Lieb lattices through non-bound electrons. This work establishes Ca_(2)I as a promising platform for exploring flat-band physics and correlated electronic states, opening avenues for novel quantum phenomena in electride-based materials.展开更多
This paper presents a comprehensive framework for analyzing phase transitions in collective models such as theVicsek model under various noise types. The Vicsek model, focusing on understanding the collective behavior...This paper presents a comprehensive framework for analyzing phase transitions in collective models such as theVicsek model under various noise types. The Vicsek model, focusing on understanding the collective behaviors of socialanimals, is known due to its discontinuous phase transitions under vector noise. However, its behavior under scalar noiseremains less conclusive. Renowned for its efficacy in the analysis of complex systems under both equilibrium and nonequilibriumstates, the eigen microstate method is employed here for a quantitative examination of the phase transitions inthe Vicsek model under both vector and scalar noises. The study finds that the Vicsek model exhibits discontinuous phasetransitions regardless of noise type. Furthermore, the dichotomy method is utilized to identify the critical points for thesephase transitions. A significant finding is the observed increase in the critical point for discontinuous phase transitions withescalation of population density.展开更多
In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on...In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model's ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength.展开更多
In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena s...In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study＇s results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow.展开更多
The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-...The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was investigated.Characterization of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample magnetometer.The results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)structure.The bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then increases.Magnetic investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.展开更多
Based on cluster variation method (CVM) and natural iteration method (MM),order-disorder phase transition in the intercalation compounds M_(1/2)TiS_2 is simulated bycomputer. The favorable conditions, under which 3^(1...Based on cluster variation method (CVM) and natural iteration method (MM),order-disorder phase transition in the intercalation compounds M_(1/2)TiS_2 is simulated bycomputer. The favorable conditions, under which 3^(1/2)a_0 x a_0 superstructure is formed, aregiven, and the results are in good agreement with the experiments and theoretical calculations. Therelationship between critical temperature and M-ion-vacancy interaction parameter is linear.展开更多
Bacterial flagellar filament can undergo a stress-induced polymorphic phase transition in both vitro and vivo environments.The filament has 12 different helical forms(phases)characterized by different pitch lengths an...Bacterial flagellar filament can undergo a stress-induced polymorphic phase transition in both vitro and vivo environments.The filament has 12 different helical forms(phases)characterized by different pitch lengths and helix radii.When subjected to the frictional force of flowing fluid,the filament changes between a left-handed normal phase and a right-handed semi-coiled phase via phase nucleation and growth.This paper develops non-local finite element method(FEM)to simulate the phase transition under a displacement-controlled loading condition(controlled helix-twist).The FEM formulation is based on the Ginzburg-Landau theory using a one-dimensional non-convex and non-local continuum model.To describe the processes of the phase nucleation and growth,viscosity-type kinetics is also used.The non-local FEM simulation captures the main features of the phase transition:two-phase coexistence with an interface of finite thickness,phase nucleation and phase growth with interface propagation.The non-local FEM model provides a tool to study the effects of the interfacial energy/thickness and loading conditions on the phase transition.展开更多
Scandium-substituted Al_(2)Mo_(3)O_(12)ceramics corresponding to the general formula Al_(2-x)Sc_(x)Mo_(3)O_(12)(0≤x≤0.5)were fabricated by the co-precipitation reaction.Sc^(3+)is proved to successfully replace Al^(3...Scandium-substituted Al_(2)Mo_(3)O_(12)ceramics corresponding to the general formula Al_(2-x)Sc_(x)Mo_(3)O_(12)(0≤x≤0.5)were fabricated by the co-precipitation reaction.Sc^(3+)is proved to successfully replace Al^(3+)and reduces the average grain size of the Al_(2-x)Sc_(x)Mo_(3)O_(12)ceramics from 6µm to 1µm.Sc^(3+)substitution induces a crystal structure change from monoclinic to orthorhombic symmetry.展开更多
The structural, electronic and mechanical properties of transition metal hydrides （TMH, TM=Mo, Tc, Ru） are investigated by means of first principles calculation based on density fimctional theory with generalized gr...The structural, electronic and mechanical properties of transition metal hydrides （TMH, TM=Mo, Tc, Ru） are investigated by means of first principles calculation based on density fimctional theory with generalized gradient approximation. Among the five crystallographic structures that have been investigated, the cubic phase is found to be more stable than the hexagonal ones. A structural phase transition from ZB to WC in Moll, NaC1 to NiAs in TcH and NaCI to ZB to NiAs in RuH is also predicted under high pressure. The calculated elastic constants indicate that all the three hydrides are mechanically stable at ambient pressure.展开更多
The two-component cold atom systems with anisotropic hopping amplitudes can be phenomenologically described by a two-dimensional Ising-XY coupled model with spatial anisotropy.At low temperatures,theoretical predictio...The two-component cold atom systems with anisotropic hopping amplitudes can be phenomenologically described by a two-dimensional Ising-XY coupled model with spatial anisotropy.At low temperatures,theoretical predictions[Phys.Rev.A 72053604(2005)]and[arXiv:0706.1609]indicate the existence of a topological ordered phase characterized by Ising and XY disorder but with 2XY ordering.However,due to ergodic difficulties faced by Monte Carlo methods at low temperatures,this topological phase has not been numerically explored.We propose a linear cluster updating Monte Carlo method,which flips spins without rejection in the anisotropy limit but does not change the energy.Using this scheme and conventional Monte Carlo methods,we succeed in revealing the nature of topological phases with half-vortices and domain walls.In the constructed global phase diagram,Ising and XY-type transitions are very close to each other and differ significantly from the schematic phase diagram reported earlier.We also propose and explore a wide range of quantities,including magnetism,superfluidity,specific heat,susceptibility,and even percolation susceptibility,and obtain consistent and reliable results.Furthermore,we observed first-order transitions characterized by common intersection points in magnetizations for different system sizes,as opposed to the conventional phase transition where Binder cumulants of various sizes share common intersections.The critical exponents of different types of phase transitions are reasonably fitted.The results are useful to help cold atom experiments explore the half-vortex topological phase.展开更多
In this paper we study a quasi-linear hyperbolic system, with some integral operators, arising from an atmospheric model on the transition of water. By using the method of characteristics and a fixed point argument, w...In this paper we study a quasi-linear hyperbolic system, with some integral operators, arising from an atmospheric model on the transition of water. By using the method of characteristics and a fixed point argument, we prove a theorem of existence, uniqueness and continuous dependence on data, in Lipschitz class, of the solution to this problem.展开更多
Understanding the dynamics of phase boundaries in fluids requires quantitative knowledge about the microscale processes at the interface.We consider the sharp-interface motion of the compressible two-component flow an...Understanding the dynamics of phase boundaries in fluids requires quantitative knowledge about the microscale processes at the interface.We consider the sharp-interface motion of the compressible two-component flow and propose a heterogeneous multiscale method(HMM)to describe the flow fields accurately.The multiscale approach combines a hyperbolic system of balance laws on the continuum scale with molecular-dynamics(MD)simulations on the microscale level.Notably,the multiscale approach is necessary to compute the interface dynamics because there is—at present—no closed continuum-scale model.The basic HMM relies on a moving-mesh finite-volume method and has been introduced recently for the compressible one-component flow with phase transitions by Magiera and Rohde in(J Comput Phys 469:111551,2022).To overcome the numerical complexity of the MD microscale model,a deep neural network is employed as an efficient surrogate model.The entire approach is finally applied to simulate droplet dynamics for argon-methane mixtures in several space dimensions.To our knowledge,such compressible two-phase dynamics accounting for microscale phase-change transfer rates have not yet been computed.展开更多
Two new cadmium sulfamates,namely,centrosymmetric Cd(NH_(2)SO_(3))_(2)·2H_(2)O and noncentrosymmetric Cd(NH_(2)SO_(3))_(2) have been successfully synthesized.Crystals of Cd(NH_(2)SO_(3))_(2)·2H_(2)O grown us...Two new cadmium sulfamates,namely,centrosymmetric Cd(NH_(2)SO_(3))_(2)·2H_(2)O and noncentrosymmetric Cd(NH_(2)SO_(3))_(2) have been successfully synthesized.Crystals of Cd(NH_(2)SO_(3))_(2)·2H_(2)O grown using an aquasolution method reveal an infinite chain structure consisting of trans-[CdO_(2)(H_(2)O)_(2)(NH_(2))_(2)]octahedra and[NH_(2)SO_(3)]units.Crystals of Cd(NH_(2)SO_(3))_(2) obtained during the process of dehydration of Cd(NH_(2)SO_(3))_(2)·2H_(2)O exhibit a 3D framework composed of cis-[CdO_(4)(NH_(2))_(2)]octahedra and[NH_(2)SO_(3)]tetrahedra.Temperature-and humidity-induced reversible phase transitions of the title compounds are observed,which is confirmed by TGA and PXRD.Cd(NH_(2)SO_(3))_(2) exhibits a phase-matchable SHG response of ca.0.15×KDP.Interestingly,nitrogen-containing[CdO_(4)N_(2)]octahedra are found in the metal sulfamates for the first time.The unique arrangement is discussed with the hard-and-soft acids and bases theory and further compared with other existing[MO_(6)](M=Na,Mg)octahedra in sulfamates.In addition,the discovery would provide a new perspective to design new materials by adjusting the structural arrangement for polar anionic groups.展开更多
The phase transition process in magnetic materials entails novel physical properties closely linked to electron distribution and energy states.However,the absence of an electron-scale calculation method for magnetic t...The phase transition process in magnetic materials entails novel physical properties closely linked to electron distribution and energy states.However,the absence of an electron-scale calculation method for magnetic transition states hinders accurate description of electronic state changes.This paper presents a calculation method for magnetic phase transition string transition states,integrating excited state calculation with magnetic confinement.Using the ferromagnetic to antiferromagnetic phase transition in FeRh alloy as a case study,we demonstrate precise calculation of phase transition energy barrier and their influence on magnetic moment due to charge distribution.The method achieves high accuracy and reveals the interplay between lattice and magnetic coupling during magnetic phase transitions as well.This breakthrough not only sheds light on the fundamental mechanisms underlying magnetic phase transitions but also sets a precedent for future research in magnetic condensed matter physics,providing invaluable insights into the interplay between electron,lattice and magnetization.展开更多
Optimal microstructure design of battery materials is critical to enhance the performance of batteries for tailored applications such as high power cells.Accurate simulation of the thermodynamics,transport,and electro...Optimal microstructure design of battery materials is critical to enhance the performance of batteries for tailored applications such as high power cells.Accurate simulation of the thermodynamics,transport,and electrochemical reaction kinetics in commonly used polycrystalline battery materials remains a challenge.Here,we combine state-of-the-art multiphase field modelling with the smoothed boundary method to accurately simulate complex battery microstructures and multiphase physics.The phase-field method is employed to parameterize complex open pore cathode microstructures and we present a formulation to impose galvanostatic charging conditions on the diffuse boundary representation.By extending the smoothed boundary method to the multiphase-field method,we build a simulation framework which is capable of simulating the coupled effects of intercalation,anisotropic diffusion,and phase transitions in arbitrary complex polycrystalline agglomerates.This method is directly compatible with voxel-based data,e.g.,from X-ray tomography.The simulation framework is used to study the reversible phase transitions in Li_(X)NiO_(2)in dense and nanoporous agglomerates.Based on the thermodynamic consistency of phase-field approaches with ab-initio simulations and the open circuit potential,we reconstruct the Gibbs free energies of four individual phases(H1,M,H_(2)and H_(3))from experimental cycling data.The results show remarkable agreement with previously published DFT results.From charge simulations,we discover a strong influence of particle morphology on the phase transition behaviour,in particular a shrinking core-like behaviour in dense polycrystalline structures and a particle-by-particle mosaic behavior in nanoporous samples.Overall,the proposed simulation framework enables the detailed study of phase transitions in intercalation materials to enhance microstructure design and fast charging protocols.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.12175031Guangdong Provincial Key Laboratory of Nuclear Science under Grant No.2019B121203010。
文摘We investigate the boundary effect of quark–gluon plasma(QGP)droplets and the self-similarity effect of hadrons on QGP–hadron phase transition.In intermediate-or low-energy collisions,when the transverse momentum is below quantum chromodynamics(QCD)scale,QGP cannot be produced.However,if the transverse momentum changes to a relatively large value,a smallscale QGP droplet is produced.The modified MIT bag model with the multiple reflection expansion method is employed to study the QGP droplet with the curved boundary effect.It is found that the energy density,entropy density and pressure of QGP with the influence are smaller than those without the influence.In the hadron phase,we propose the two-body fractal model(TBFM)to study the self-similarity structure,arising from resonance,quantum correlation and interaction effects.It is observed that the energy density,entropy density and pressure increase due to the self-similarity structure.We calculate the transverse momentum spectra of pions with the self-similarity structure influence,which show good agreement with experimental data.Considering both boundary effect and self-similarity structure influence,our model predicts an increase in the transition temperature compared to the scenarios without these two effects in the High Intensity heavy-ion Accelerator Facility(HIAF)energy region,2.2 GeV to approximately 4.5 GeV.
基金supported by the National Natural Science Foundation of China(Grant Nos.12125404,T2495231,123B2049,and 12204138)the National Key R&D Program of China(Grant No.2022YFA1403201)+7 种基金the Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0607000)the Basic Research Program of Jiangsu (Grant Nos.BK20233001 and BK20241253)the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant Nos.2024ZB002,2024ZB075,2025ZB440 and2025ZB852)the China Postdoctoral Science Foundation (Grant No.2025M773331)the Postdoctoral Fellowship Program of CPSF (Grant No.GZC20240695 and GZC20252202)the AI&AI for Science Program of Nanjing UniversityArtificial Intelligence and Quantum physics (AIQ) program of Nanjing Universitythe Fundamental Research Funds for the Central Universities。
文摘The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices. In this work, we propose the concept of a Lieb electride, where the non-bound electrons gather at the middle edges,behaving as the quasi-atoms of a Lieb lattice, enabling the emergence of flat bands. Using crystal structure prediction method MAGUS and first-principles calculations, we predict a stable candidate, Ca_(2)I, at ambient pressure. Distinct from conventional electrides with localized electrons at cavity centers, Ca_(2)I features interstitial electrons situated at cavity edges. The resultant flat bands lie close to the Fermi level, giving rise to a pronounced peak in the density of states and leading to Stoner-type ferromagnetism. With increasing pressures, we observe quantum phase transitions from ferromagnetic to non-magnetic and finally to antiferromagnetic orders in Ca_(2)I.Intriguingly, superconductivity emerges in the antiferromagnetic region, suggesting potential competition between these correlated states. Our study not only extends the concepts of electrides but also provides a novel strategy for realizing Lieb lattices through non-bound electrons. This work establishes Ca_(2)I as a promising platform for exploring flat-band physics and correlated electronic states, opening avenues for novel quantum phenomena in electride-based materials.
基金the National Natural Science Foundation of China(Grant No.62273033).
文摘This paper presents a comprehensive framework for analyzing phase transitions in collective models such as theVicsek model under various noise types. The Vicsek model, focusing on understanding the collective behaviors of socialanimals, is known due to its discontinuous phase transitions under vector noise. However, its behavior under scalar noiseremains less conclusive. Renowned for its efficacy in the analysis of complex systems under both equilibrium and nonequilibriumstates, the eigen microstate method is employed here for a quantitative examination of the phase transitions inthe Vicsek model under both vector and scalar noises. The study finds that the Vicsek model exhibits discontinuous phasetransitions regardless of noise type. Furthermore, the dichotomy method is utilized to identify the critical points for thesephase transitions. A significant finding is the observed increase in the critical point for discontinuous phase transitions withescalation of population density.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11275118,11404198,91430109,61505100,51502189the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province(STIP)under Grant No.2014102+2 种基金the Launch of the Scientific Research of Shanxi University under Grant No.011151801004the National Fundamental Fund of Personnel Training under Grant No.J1103210The Natural Science Foundation of Shanxi Province under Grant No.2015011008
文摘In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model's ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength.
文摘In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study＇s results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow.
文摘The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was investigated.Characterization of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample magnetometer.The results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)structure.The bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then increases.Magnetic investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.
基金This work was supported by the Foundation of Civil Aviation University of China (No. 2001-3-18).
文摘Based on cluster variation method (CVM) and natural iteration method (MM),order-disorder phase transition in the intercalation compounds M_(1/2)TiS_2 is simulated bycomputer. The favorable conditions, under which 3^(1/2)a_0 x a_0 superstructure is formed, aregiven, and the results are in good agreement with the experiments and theoretical calculations. Therelationship between critical temperature and M-ion-vacancy interaction parameter is linear.
基金supported by the Hong Kong University of Science and Technology and the National Natural Science Foundation of China(10902013)
文摘Bacterial flagellar filament can undergo a stress-induced polymorphic phase transition in both vitro and vivo environments.The filament has 12 different helical forms(phases)characterized by different pitch lengths and helix radii.When subjected to the frictional force of flowing fluid,the filament changes between a left-handed normal phase and a right-handed semi-coiled phase via phase nucleation and growth.This paper develops non-local finite element method(FEM)to simulate the phase transition under a displacement-controlled loading condition(controlled helix-twist).The FEM formulation is based on the Ginzburg-Landau theory using a one-dimensional non-convex and non-local continuum model.To describe the processes of the phase nucleation and growth,viscosity-type kinetics is also used.The non-local FEM simulation captures the main features of the phase transition:two-phase coexistence with an interface of finite thickness,phase nucleation and phase growth with interface propagation.The non-local FEM model provides a tool to study the effects of the interfacial energy/thickness and loading conditions on the phase transition.
基金National Natural Science Foundation of China(No.51602280 and 51102207)Qing Lan Project of Jiangsu Province,Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX18_0794).
文摘Scandium-substituted Al_(2)Mo_(3)O_(12)ceramics corresponding to the general formula Al_(2-x)Sc_(x)Mo_(3)O_(12)(0≤x≤0.5)were fabricated by the co-precipitation reaction.Sc^(3+)is proved to successfully replace Al^(3+)and reduces the average grain size of the Al_(2-x)Sc_(x)Mo_(3)O_(12)ceramics from 6µm to 1µm.Sc^(3+)substitution induces a crystal structure change from monoclinic to orthorhombic symmetry.
文摘The structural, electronic and mechanical properties of transition metal hydrides （TMH, TM=Mo, Tc, Ru） are investigated by means of first principles calculation based on density fimctional theory with generalized gradient approximation. Among the five crystallographic structures that have been investigated, the cubic phase is found to be more stable than the hexagonal ones. A structural phase transition from ZB to WC in Moll, NaC1 to NiAs in TcH and NaCI to ZB to NiAs in RuH is also predicted under high pressure. The calculated elastic constants indicate that all the three hydrides are mechanically stable at ambient pressure.
基金Project supported by the Hefei National Research Center for Physical Sciences at the Microscale (Grant No.KF2021002)the Natural Science Foundation of Shanxi Province,China (Grant Nos.202303021221029 and 202103021224051)+2 种基金the National Natural Science Foundation of China (Grant Nos.11975024,12047503,and 12275263)the Anhui Provincial Supporting Program for Excellent Young Talents in Colleges and Universities (Grant No.gxyq ZD2019023)the National Key Research and Development Program of China (Grant No.2018YFA0306501)。
文摘The two-component cold atom systems with anisotropic hopping amplitudes can be phenomenologically described by a two-dimensional Ising-XY coupled model with spatial anisotropy.At low temperatures,theoretical predictions[Phys.Rev.A 72053604(2005)]and[arXiv:0706.1609]indicate the existence of a topological ordered phase characterized by Ising and XY disorder but with 2XY ordering.However,due to ergodic difficulties faced by Monte Carlo methods at low temperatures,this topological phase has not been numerically explored.We propose a linear cluster updating Monte Carlo method,which flips spins without rejection in the anisotropy limit but does not change the energy.Using this scheme and conventional Monte Carlo methods,we succeed in revealing the nature of topological phases with half-vortices and domain walls.In the constructed global phase diagram,Ising and XY-type transitions are very close to each other and differ significantly from the schematic phase diagram reported earlier.We also propose and explore a wide range of quantities,including magnetism,superfluidity,specific heat,susceptibility,and even percolation susceptibility,and obtain consistent and reliable results.Furthermore,we observed first-order transitions characterized by common intersection points in magnetizations for different system sizes,as opposed to the conventional phase transition where Binder cumulants of various sizes share common intersections.The critical exponents of different types of phase transitions are reasonably fitted.The results are useful to help cold atom experiments explore the half-vortex topological phase.
文摘In this paper we study a quasi-linear hyperbolic system, with some integral operators, arising from an atmospheric model on the transition of water. By using the method of characteristics and a fixed point argument, we prove a theorem of existence, uniqueness and continuous dependence on data, in Lipschitz class, of the solution to this problem.
基金Funding Open Access funding enabled and organized by Projekt DEAL.When preparing this manuscript,the authors have kept the COPE guidelines on how to deal with potential acts of misconduct.The research leading to these results received funding from Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)through the project SFB-TRR 75 with the project number 84292822the DFG under Germanys Excellence Strategy-EXC2075with the project number390740016.
文摘Understanding the dynamics of phase boundaries in fluids requires quantitative knowledge about the microscale processes at the interface.We consider the sharp-interface motion of the compressible two-component flow and propose a heterogeneous multiscale method(HMM)to describe the flow fields accurately.The multiscale approach combines a hyperbolic system of balance laws on the continuum scale with molecular-dynamics(MD)simulations on the microscale level.Notably,the multiscale approach is necessary to compute the interface dynamics because there is—at present—no closed continuum-scale model.The basic HMM relies on a moving-mesh finite-volume method and has been introduced recently for the compressible one-component flow with phase transitions by Magiera and Rohde in(J Comput Phys 469:111551,2022).To overcome the numerical complexity of the MD microscale model,a deep neural network is employed as an efficient surrogate model.The entire approach is finally applied to simulate droplet dynamics for argon-methane mixtures in several space dimensions.To our knowledge,such compressible two-phase dynamics accounting for microscale phase-change transfer rates have not yet been computed.
基金supported by the National Research Foundation of Korea(NRF)funded by the Ministry of ScienceICT(Grant No.2018R1A5A1025208 and 2019R1A2C3005530).
文摘Two new cadmium sulfamates,namely,centrosymmetric Cd(NH_(2)SO_(3))_(2)·2H_(2)O and noncentrosymmetric Cd(NH_(2)SO_(3))_(2) have been successfully synthesized.Crystals of Cd(NH_(2)SO_(3))_(2)·2H_(2)O grown using an aquasolution method reveal an infinite chain structure consisting of trans-[CdO_(2)(H_(2)O)_(2)(NH_(2))_(2)]octahedra and[NH_(2)SO_(3)]units.Crystals of Cd(NH_(2)SO_(3))_(2) obtained during the process of dehydration of Cd(NH_(2)SO_(3))_(2)·2H_(2)O exhibit a 3D framework composed of cis-[CdO_(4)(NH_(2))_(2)]octahedra and[NH_(2)SO_(3)]tetrahedra.Temperature-and humidity-induced reversible phase transitions of the title compounds are observed,which is confirmed by TGA and PXRD.Cd(NH_(2)SO_(3))_(2) exhibits a phase-matchable SHG response of ca.0.15×KDP.Interestingly,nitrogen-containing[CdO_(4)N_(2)]octahedra are found in the metal sulfamates for the first time.The unique arrangement is discussed with the hard-and-soft acids and bases theory and further compared with other existing[MO_(6)](M=Na,Mg)octahedra in sulfamates.In addition,the discovery would provide a new perspective to design new materials by adjusting the structural arrangement for polar anionic groups.
基金funded by the National Natural Science Foundation of China(Grant Nos.51790494 and 12088101).
文摘The phase transition process in magnetic materials entails novel physical properties closely linked to electron distribution and energy states.However,the absence of an electron-scale calculation method for magnetic transition states hinders accurate description of electronic state changes.This paper presents a calculation method for magnetic phase transition string transition states,integrating excited state calculation with magnetic confinement.Using the ferromagnetic to antiferromagnetic phase transition in FeRh alloy as a case study,we demonstrate precise calculation of phase transition energy barrier and their influence on magnetic moment due to charge distribution.The method achieves high accuracy and reveals the interplay between lattice and magnetic coupling during magnetic phase transitions as well.This breakthrough not only sheds light on the fundamental mechanisms underlying magnetic phase transitions but also sets a precedent for future research in magnetic condensed matter physics,providing invaluable insights into the interplay between electron,lattice and magnetization.
基金funded by the German Research Foundation (DFG) under Project ID 390874152 (POLiS Cluster of Excellence)Support by the Helmholtz association though the MTET programme (no. 38.02.01) is gratefully acknowledged.
文摘Optimal microstructure design of battery materials is critical to enhance the performance of batteries for tailored applications such as high power cells.Accurate simulation of the thermodynamics,transport,and electrochemical reaction kinetics in commonly used polycrystalline battery materials remains a challenge.Here,we combine state-of-the-art multiphase field modelling with the smoothed boundary method to accurately simulate complex battery microstructures and multiphase physics.The phase-field method is employed to parameterize complex open pore cathode microstructures and we present a formulation to impose galvanostatic charging conditions on the diffuse boundary representation.By extending the smoothed boundary method to the multiphase-field method,we build a simulation framework which is capable of simulating the coupled effects of intercalation,anisotropic diffusion,and phase transitions in arbitrary complex polycrystalline agglomerates.This method is directly compatible with voxel-based data,e.g.,from X-ray tomography.The simulation framework is used to study the reversible phase transitions in Li_(X)NiO_(2)in dense and nanoporous agglomerates.Based on the thermodynamic consistency of phase-field approaches with ab-initio simulations and the open circuit potential,we reconstruct the Gibbs free energies of four individual phases(H1,M,H_(2)and H_(3))from experimental cycling data.The results show remarkable agreement with previously published DFT results.From charge simulations,we discover a strong influence of particle morphology on the phase transition behaviour,in particular a shrinking core-like behaviour in dense polycrystalline structures and a particle-by-particle mosaic behavior in nanoporous samples.Overall,the proposed simulation framework enables the detailed study of phase transitions in intercalation materials to enhance microstructure design and fast charging protocols.
