Based on NII spectra, some transition probabilities for 2p4f-2p3d and 2s2p23d-2s2p23p are obtained by a semi- classical method. The results are in good agreement with other measurements and the data reported by the Na...Based on NII spectra, some transition probabilities for 2p4f-2p3d and 2s2p23d-2s2p23p are obtained by a semi- classical method. The results are in good agreement with other measurements and the data reported by the National Institute of Standards and Technology. The transition probability for a line of 424.18nm is reported for the first time. Meanwhile, a feasible method of calculating transition parameters related to special excited configurations or highly excited states is provided.展开更多
Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. ...Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting （CZC） method is proposed in this paper, by combining the Duffing oscillator＇s phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent （MLE） method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.展开更多
The Cu?Al composite casts were prepared by the method of pouring molten aluminum. The solidification process and themicrostructure of the transition layer were investigated during the recombination process of the liqu...The Cu?Al composite casts were prepared by the method of pouring molten aluminum. The solidification process and themicrostructure of the transition layer were investigated during the recombination process of the liquid Al and the solid Cu. The results reveal that the microstructure of the transition layer in the Cu?Al composite cast consists of α(Al)+α(Al)?CuAl2 eutectic,α(Al)?CuAl2 eutectic, CuAl2+α(Al)?CuAl2 eutectic and Cu9Al4. Additionally, the pouring temperature, cooling mode of the Cu platesurface and start time of the forced cooling after pouring have no effect on the microstructure species. But the proportion of thevarious microstructures in the transition layer changes with the process parameters. The pure Al at the top of the transition layer startsto solidify first and then the α(Al) phase grows in a dendritic way, while the CuAl2 phase exhibits plane or cellular crystal growth from the two sides of the transition layer towards its interior. The stronger the cooling intensity of the Cu plate outer surface, the more developed the dendrite, and the easier it is for the CuAl2 phase to grow into a plane crystal.展开更多
The domain size of spiral waves is an important issue in studies of two-dimensional （2D） spatiotemporal patterns. In this work, we use the 2D complex Ginzburg-Landau equation （CGLE） as our model and find that an i...The domain size of spiral waves is an important issue in studies of two-dimensional （2D） spatiotemporal patterns. In this work, we use the 2D complex Ginzburg-Landau equation （CGLE） as our model and find that an initially big spiral can successfully transfer to several small spirals by applying a pulse array method. The impacts of several important factors, such as array density, controlling intensity and pulsing time, are investigated. This control approach may be useful for the control of 2D spatiotemporal patterns and has potential applications in the control of some realistic systems, such as meteorological and cardiac systems.展开更多
Columnar to equiaxial crystal transition(CET)is an important technological feature in many casting processes.This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiati...Columnar to equiaxial crystal transition(CET)is an important technological feature in many casting processes.This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiation in-situ imaging and phase-field method.Results show that the grain size,dendrite tip radius,and secondary dendrite arm spacing(SDAS)all exponentially decrease with an increase in cooling rate(Vc).The variation in the radius of the dendritic tip is similar to the prediction of the Hunt model,while the variation in the SDAS is close to the Bouchard-Kirkaldy model.It is worth noting that the CET is promoted by a decrease in the temperature gradient(G)and an increase in the cooling rate(Vc).In both equiaxed and columnar crystal regions,the dendrite tip growth rate and solid phase volume fraction increase with increasing G and Vc.In addition,the CET process has been predicted by simulation.The results are consistent with the predictions of the GTK model,which is important for the in-depth study of the dendrite morphology in different crystallization regions.In the final stage,the effects of different critical subcooling degrees and nucleation densities on the CET were explored.The results show that increasing the critical nucleation supercooling degree can inhibit the generation of equiaxial crystals,while increasing the nucleation density helps to promote the CET.展开更多
In order to smooth the trajectory of a robot and reduce dwell time,a transition curve is introduced between two adjacent curves in three-dimensional space.G2 continuity is guaranteed to transit smoothly.To minimize th...In order to smooth the trajectory of a robot and reduce dwell time,a transition curve is introduced between two adjacent curves in three-dimensional space.G2 continuity is guaranteed to transit smoothly.To minimize the amount of calculation,cubic and quartic Bezier curves are both analyzed.Furthermore,the contour curve is characterized by a transition parameter which defines the distance to the corner of the deviation.How to define the transition points for different curves is presented.A general move command interface is defined for receiving the curve limitations and transition parameters.Then,how to calculate the control points of the cubic and quartic Bezier curves is analyzed and given.Different situations are discussed separately,including transition between two lines,transition between a line and a circle,and transition between two circles.Finally,the experiments are carried out on a six degree of freedom(DOF) industrial robot to validate the proposed method.Results of single transition and multiple transitions are presented.The trajectories in the joint space are also analyzed.The results indicate that the method achieves G2 continuity within the transition constraint and has good efficiency and adaptability.展开更多
Two-dimensional(2D)transition metal sulfides(TMDs)are emerging and highly well received 2D materials,which are considered as an ideal 2D platform for studying various electronic properties and potential applications d...Two-dimensional(2D)transition metal sulfides(TMDs)are emerging and highly well received 2D materials,which are considered as an ideal 2D platform for studying various electronic properties and potential applications due to their chemical diversity.Converting 2D TMDs into one-dimensional(1D)TMDs nanotubes can not only retain some advantages of 2D nanosheets but also providing a unique direction to explore the novel properties of TMDs materials in the 1D limit.However,the controllable preparation of high-quality nanotubes remains a major challenge.It is very necessary to review the advanced development of one-dimensional transition metal dichalcogenide nanotubes from preparation to application.Here,we first summarize a series of bottom-up synthesis methods of 1D TMDs,such as template growth and metal catalyzed method.Then,top-down synthesis methods are summarized,which included selfcuring and stacking of TMDs nanosheets.In addition,we discuss some key applications that utilize the properties of 1D-TMDs nanotubes in the areas of catalyst preparation,energy storage,and electronic devices.Last but not least,we prospect the preparation methods of high-quality 1D-TMDs nanotubes,which will lay a foundation for the synthesis of high-performance optoelectronic devices,catalysts,and energy storage components.展开更多
Sliding electrical contact is a common phenomenon in electrical equipment and affects performance.In this paper,the mechanism of sliding electric contact pair transition and the moment when transition occurs are inves...Sliding electrical contact is a common phenomenon in electrical equipment and affects performance.In this paper,the mechanism of sliding electric contact pair transition and the moment when transition occurs are investigated using the railgun as an example.Transition is the phenomenon where the contact between the armature and rails changes from solid-solid contact to solid-arc-solid contact.In this paper,the finite element-boundary element coupling method(FE-BE method)is used to simulate the process of armature movement.Then,the force,thermal,and electrical parameters on the armature/rail contact surface are analyzed to explore the development of contact separation.Finally,the occurrence of the transition is judged based on the Townsend discharge model(improved by Rogowski).A Small-caliber railgun firing test was carried out to validate the methodology presented in this paper.Results show that the drop edge of the current will result in the armature/rail not being able to make full contact,and the contact gap may break down,leading to a sharp increase in contact resistance and deterioration of railgun performance.Judging the occurrence of transition based on the evolution of the contact gap and the Townsend discharge model is reliable.The research provides new ideas for studying railgun transition and sliding electric contact failure.展开更多
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
With the wide application of GPS technology, the application of the system of space rectangular coordinates is more and more extensive. Transformation of space rectangular coordinates into geodetic coordinates becomes...With the wide application of GPS technology, the application of the system of space rectangular coordinates is more and more extensive. Transformation of space rectangular coordinates into geodetic coordinates becomes a very popular problem. In order to evaluate various kinds of algorithms existing for solving the problem, three evaluation criteria of the algorithm were put forward at first, that is, precision, calculation speed and algorithm regional suitability. After given some basic formula, three kinds of representative algorithms, classics iteration algorithm, ellipsoidal parameter transformation algorithm and rational polynomials approximation algorithm were introduced. Through a test program made by MATLAB, these three kinds of algorithms were compared. Some helpful conclusions were drawn.展开更多
This paper investigates the ergodicity and weak convergence of transition probabilities for two-dimensional stochastic primitive equations driven by multiplicative noise.The existence of invariant measures is establis...This paper investigates the ergodicity and weak convergence of transition probabilities for two-dimensional stochastic primitive equations driven by multiplicative noise.The existence of invariant measures is established using the classical Krylov-Bogoliubov theory.The uniqueness of invariant measures and the weak convergence of transition probabilities are demonstrated through the application of the asymptotic coupling method and Foias-Prodi estimate.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
Based on X_α multiple scattering one-electron wave functions, a way for solving the many-electron Schrodinger equation by means of irreducible tensor method is reported. As an application, the analysis of the spectra...Based on X_α multiple scattering one-electron wave functions, a way for solving the many-electron Schrodinger equation by means of irreducible tensor method is reported. As an application, the analysis of the spectra of molecule NIF_6^(4-) is presented.展开更多
This paper shows that the experimental results of quantum well energy transitions can be found numerically. The cases of several ZnO-ZnMgO wells are considered and their excitonic transition energies were calculated u...This paper shows that the experimental results of quantum well energy transitions can be found numerically. The cases of several ZnO-ZnMgO wells are considered and their excitonic transition energies were calculated using the finite difference method. In that way, the one-dimensional Schrödinger equation has been solved by using the BLAS and LAPACK libraries. The numerical results are in good agreement with the experimental ones.展开更多
Direct Monte Carlo(MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on ...Direct Monte Carlo(MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on direct MC simulation is proposed to solve the problem in this paper.This method biases transition rates of the components by adding virtual components to them in series to increase the occurrence probability of the rare event,hence the decrease in the variance of MC estimator.Several cases are used to benchmark this method.The results show that the method is effective at modeling system failure and is more efficient at collecting evidence of rare events than the direct MC simulation.The performance is greatly improved by the biasing transition rate method.展开更多
As an improved guidance method,the attitude head pursuit guidance （AHPG） law enables the attitude pursuit guidance （APG） law to be more suited to transition guidance of air-to-ground missiles. By adding a head ang...As an improved guidance method,the attitude head pursuit guidance （AHPG） law enables the attitude pursuit guidance （APG） law to be more suited to transition guidance of air-to-ground missiles. By adding a head angle into the attitude angle of APG,AHPG directs the missile axis onto the line of sight （LOS）. The maximum range trajectory simulation shows that the elevator deflection angle reaches the saturated value of 10° at the outset and the impact angle is less than 60° when APG is used as transi-tion guidance law. However,the elevator deflection angle on the whole trajectory is reduced to under 5° and the impact angle increased to over 60° when AHPG is used. The formulae to calculate head angles are derived for different target distributions. The simulation of multiple trajectories shows that with the help of the formulae based on AHPG law,the same performance could be achieved.展开更多
This paper concerns the calculation of wave height exceedance probabilities for nonlinear irregular waves in transitional water depths, and a Transformed Rayleigh method is first proposed for carrying out the calculat...This paper concerns the calculation of wave height exceedance probabilities for nonlinear irregular waves in transitional water depths, and a Transformed Rayleigh method is first proposed for carrying out the calculation. In the proposed Transformed Rayleigh method, the transformation model is chosen to be a monotonic exponential function, calibrated such that the first three moments of the transformed model match the moments of the true process. The proposed new method has been applied for calculating the wave height exceedance probabilities of a sea state with the surface elevation data measured at the Poseidon platform. It is demonstrated in this case that the proposed new method can offer better predictions than those by using the conventional Rayleigh wave height distribution model. The proposed new method has been further applied for calculating the total horizontal loads on a generic jacket, and its accuracy has once again been substantiated. The research findings gained from this study demonstrate that the proposed Transformed Rayleigh model can be utilized as a promising alternative to the well-established nonlinear wave height distribution models.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 40475007）.
文摘Based on NII spectra, some transition probabilities for 2p4f-2p3d and 2s2p23d-2s2p23p are obtained by a semi- classical method. The results are in good agreement with other measurements and the data reported by the National Institute of Standards and Technology. The transition probability for a line of 424.18nm is reported for the first time. Meanwhile, a feasible method of calculating transition parameters related to special excited configurations or highly excited states is provided.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047 and 61071025)
文摘Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting （CZC） method is proposed in this paper, by combining the Duffing oscillator＇s phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent （MLE） method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.
基金Project(LJQ2014062)supported by the Outstanding Young Scholars in Colleges and Universities of Liaoning Province,China
文摘The Cu?Al composite casts were prepared by the method of pouring molten aluminum. The solidification process and themicrostructure of the transition layer were investigated during the recombination process of the liquid Al and the solid Cu. The results reveal that the microstructure of the transition layer in the Cu?Al composite cast consists of α(Al)+α(Al)?CuAl2 eutectic,α(Al)?CuAl2 eutectic, CuAl2+α(Al)?CuAl2 eutectic and Cu9Al4. Additionally, the pouring temperature, cooling mode of the Cu platesurface and start time of the forced cooling after pouring have no effect on the microstructure species. But the proportion of thevarious microstructures in the transition layer changes with the process parameters. The pure Al at the top of the transition layer startsto solidify first and then the α(Al) phase grows in a dendritic way, while the CuAl2 phase exhibits plane or cellular crystal growth from the two sides of the transition layer towards its interior. The stronger the cooling intensity of the Cu plate outer surface, the more developed the dendrite, and the easier it is for the CuAl2 phase to grow into a plane crystal.
文摘The domain size of spiral waves is an important issue in studies of two-dimensional （2D） spatiotemporal patterns. In this work, we use the 2D complex Ginzburg-Landau equation （CGLE） as our model and find that an initially big spiral can successfully transfer to several small spirals by applying a pulse array method. The impacts of several important factors, such as array density, controlling intensity and pulsing time, are investigated. This control approach may be useful for the control of 2D spatiotemporal patterns and has potential applications in the control of some realistic systems, such as meteorological and cardiac systems.
基金financially supported by the Postdoctoral Research Project of Henan Province(No.202101003)the Key Research Programs of Higher Education Institutions in Henan Province(Nos.24A450003,23A460016)+2 种基金the Henan Provincial Key Laboratory of Intelligent Manufacturing of Machinery and Equipment Open Subjects(No.IM202308)the Zhengzhou University of Light Industry Doctoral Research Initiation Fund(No.2019BSJJ005)the Henan Provincial Science and Technology Tackling Project(No.23A460016).
文摘Columnar to equiaxial crystal transition(CET)is an important technological feature in many casting processes.This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiation in-situ imaging and phase-field method.Results show that the grain size,dendrite tip radius,and secondary dendrite arm spacing(SDAS)all exponentially decrease with an increase in cooling rate(Vc).The variation in the radius of the dendritic tip is similar to the prediction of the Hunt model,while the variation in the SDAS is close to the Bouchard-Kirkaldy model.It is worth noting that the CET is promoted by a decrease in the temperature gradient(G)and an increase in the cooling rate(Vc).In both equiaxed and columnar crystal regions,the dendrite tip growth rate and solid phase volume fraction increase with increasing G and Vc.In addition,the CET process has been predicted by simulation.The results are consistent with the predictions of the GTK model,which is important for the in-depth study of the dendrite morphology in different crystallization regions.In the final stage,the effects of different critical subcooling degrees and nucleation densities on the CET were explored.The results show that increasing the critical nucleation supercooling degree can inhibit the generation of equiaxial crystals,while increasing the nucleation density helps to promote the CET.
基金Supported by the National Natural Science Foundation of China(No.61573358)Research and Development of Large Multi-function Demolition Equipment in Disaster Site(No.2015BAK06B00)
文摘In order to smooth the trajectory of a robot and reduce dwell time,a transition curve is introduced between two adjacent curves in three-dimensional space.G2 continuity is guaranteed to transit smoothly.To minimize the amount of calculation,cubic and quartic Bezier curves are both analyzed.Furthermore,the contour curve is characterized by a transition parameter which defines the distance to the corner of the deviation.How to define the transition points for different curves is presented.A general move command interface is defined for receiving the curve limitations and transition parameters.Then,how to calculate the control points of the cubic and quartic Bezier curves is analyzed and given.Different situations are discussed separately,including transition between two lines,transition between a line and a circle,and transition between two circles.Finally,the experiments are carried out on a six degree of freedom(DOF) industrial robot to validate the proposed method.Results of single transition and multiple transitions are presented.The trajectories in the joint space are also analyzed.The results indicate that the method achieves G2 continuity within the transition constraint and has good efficiency and adaptability.
基金supported by the National Natural Science Foundation of China(No.22202065).
文摘Two-dimensional(2D)transition metal sulfides(TMDs)are emerging and highly well received 2D materials,which are considered as an ideal 2D platform for studying various electronic properties and potential applications due to their chemical diversity.Converting 2D TMDs into one-dimensional(1D)TMDs nanotubes can not only retain some advantages of 2D nanosheets but also providing a unique direction to explore the novel properties of TMDs materials in the 1D limit.However,the controllable preparation of high-quality nanotubes remains a major challenge.It is very necessary to review the advanced development of one-dimensional transition metal dichalcogenide nanotubes from preparation to application.Here,we first summarize a series of bottom-up synthesis methods of 1D TMDs,such as template growth and metal catalyzed method.Then,top-down synthesis methods are summarized,which included selfcuring and stacking of TMDs nanosheets.In addition,we discuss some key applications that utilize the properties of 1D-TMDs nanotubes in the areas of catalyst preparation,energy storage,and electronic devices.Last but not least,we prospect the preparation methods of high-quality 1D-TMDs nanotubes,which will lay a foundation for the synthesis of high-performance optoelectronic devices,catalysts,and energy storage components.
文摘Sliding electrical contact is a common phenomenon in electrical equipment and affects performance.In this paper,the mechanism of sliding electric contact pair transition and the moment when transition occurs are investigated using the railgun as an example.Transition is the phenomenon where the contact between the armature and rails changes from solid-solid contact to solid-arc-solid contact.In this paper,the finite element-boundary element coupling method(FE-BE method)is used to simulate the process of armature movement.Then,the force,thermal,and electrical parameters on the armature/rail contact surface are analyzed to explore the development of contact separation.Finally,the occurrence of the transition is judged based on the Townsend discharge model(improved by Rogowski).A Small-caliber railgun firing test was carried out to validate the methodology presented in this paper.Results show that the drop edge of the current will result in the armature/rail not being able to make full contact,and the contact gap may break down,leading to a sharp increase in contact resistance and deterioration of railgun performance.Judging the occurrence of transition based on the evolution of the contact gap and the Townsend discharge model is reliable.The research provides new ideas for studying railgun transition and sliding electric contact failure.
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.
文摘With the wide application of GPS technology, the application of the system of space rectangular coordinates is more and more extensive. Transformation of space rectangular coordinates into geodetic coordinates becomes a very popular problem. In order to evaluate various kinds of algorithms existing for solving the problem, three evaluation criteria of the algorithm were put forward at first, that is, precision, calculation speed and algorithm regional suitability. After given some basic formula, three kinds of representative algorithms, classics iteration algorithm, ellipsoidal parameter transformation algorithm and rational polynomials approximation algorithm were introduced. Through a test program made by MATLAB, these three kinds of algorithms were compared. Some helpful conclusions were drawn.
基金supported in part by the NSFC(12171084,12326367)the Jiangsu Provincial Scientific Research Center of Applied Mathematics(BK20233002)the fundamental Research Funds for the Central Universities(RF1028623037)。
文摘This paper investigates the ergodicity and weak convergence of transition probabilities for two-dimensional stochastic primitive equations driven by multiplicative noise.The existence of invariant measures is established using the classical Krylov-Bogoliubov theory.The uniqueness of invariant measures and the weak convergence of transition probabilities are demonstrated through the application of the asymptotic coupling method and Foias-Prodi estimate.
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.
文摘Based on X_α multiple scattering one-electron wave functions, a way for solving the many-electron Schrodinger equation by means of irreducible tensor method is reported. As an application, the analysis of the spectra of molecule NIF_6^(4-) is presented.
文摘This paper shows that the experimental results of quantum well energy transitions can be found numerically. The cases of several ZnO-ZnMgO wells are considered and their excitonic transition energies were calculated using the finite difference method. In that way, the one-dimensional Schrödinger equation has been solved by using the BLAS and LAPACK libraries. The numerical results are in good agreement with the experimental ones.
基金supported by the Special Projects of International Thermonuclear Experimental Reactor(2015GB116000)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA03040000)+1 种基金the Informatizational Special Projects of Chinese Academy of Sciences(No.XXH12504-1-09)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2014FXCX004)
文摘Direct Monte Carlo(MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on direct MC simulation is proposed to solve the problem in this paper.This method biases transition rates of the components by adding virtual components to them in series to increase the occurrence probability of the rare event,hence the decrease in the variance of MC estimator.Several cases are used to benchmark this method.The results show that the method is effective at modeling system failure and is more efficient at collecting evidence of rare events than the direct MC simulation.The performance is greatly improved by the biasing transition rate method.
文摘As an improved guidance method,the attitude head pursuit guidance （AHPG） law enables the attitude pursuit guidance （APG） law to be more suited to transition guidance of air-to-ground missiles. By adding a head angle into the attitude angle of APG,AHPG directs the missile axis onto the line of sight （LOS）. The maximum range trajectory simulation shows that the elevator deflection angle reaches the saturated value of 10° at the outset and the impact angle is less than 60° when APG is used as transi-tion guidance law. However,the elevator deflection angle on the whole trajectory is reduced to under 5° and the impact angle increased to over 60° when AHPG is used. The formulae to calculate head angles are derived for different target distributions. The simulation of multiple trajectories shows that with the help of the formulae based on AHPG law,the same performance could be achieved.
基金financially supported by the Chinese State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University(Grant No.GKZD010038)
文摘This paper concerns the calculation of wave height exceedance probabilities for nonlinear irregular waves in transitional water depths, and a Transformed Rayleigh method is first proposed for carrying out the calculation. In the proposed Transformed Rayleigh method, the transformation model is chosen to be a monotonic exponential function, calibrated such that the first three moments of the transformed model match the moments of the true process. The proposed new method has been applied for calculating the wave height exceedance probabilities of a sea state with the surface elevation data measured at the Poseidon platform. It is demonstrated in this case that the proposed new method can offer better predictions than those by using the conventional Rayleigh wave height distribution model. The proposed new method has been further applied for calculating the total horizontal loads on a generic jacket, and its accuracy has once again been substantiated. The research findings gained from this study demonstrate that the proposed Transformed Rayleigh model can be utilized as a promising alternative to the well-established nonlinear wave height distribution models.
