A geometrically nonlinear topology optimization method for continuum structures is proposed based on the independent continuous mapping method.The stress constraint problem is studied due to the importance of structur...A geometrically nonlinear topology optimization method for continuum structures is proposed based on the independent continuous mapping method.The stress constraint problem is studied due to the importance of structural strength in engineering applications.First,a topology optimization model is established for a lightweight structure with element stress as constraints.Second,the stress globalization method is adopted to convert local stress constraints into strain energy constraints,which overcomes the difficulties caused by local stress constraints,such as model establishment,sensitivity analysis,and massive solution calculations.Third,the sensitivity of the objective function and constraint function is analyzed,and the method of moving asymptotes is employed to solve the optimization model.In addition,the additive hyperelasticity technique is utilized to solve the numerical instability induced by structures undergoing large deformation.Numerical examples are given to validate the feasibility of the proposed method.The method provides a significant reference for geometrically nonlinear optimization design.展开更多
β-decay half-life and β-delayed neutron emission(βn) are of great importance in the development of basic science and industrial applications, such as nuclear physics and nuclear energy, where β--decay plays an imp...β-decay half-life and β-delayed neutron emission(βn) are of great importance in the development of basic science and industrial applications, such as nuclear physics and nuclear energy, where β--decay plays an important role. Many theoretical models have been proposed to describe β-decay half-lives, whereas the systematic study of βn is still rare. This study aimed to investigate β--decay half-lives and βn probabilities through analytical formulas and by comparing them with experimental data. Analytical formulas for β--decay properties have been proposed by considering prominent factors, that is, decay energy,odevity, and the shell effect. The bootstrap method was used to simultaneously evaluate the total uncertainty on calculations,which was composed of statistic and systematic uncertainties. β--decay half-lives, βn probabilities, and the corresponding uncertainties were evaluated for the neutron-rich region. The experimental half-lives were well reproduced. Additional predictions are also presented with theoretical uncertainties, which helps to better understand the disparity between the experimental and theoretical results.展开更多
Information on the decay process of nuclides in the superheavy region is critical in investigating new elements beyond oganesson and the island of stability.This paper presents the application of a random forest algor...Information on the decay process of nuclides in the superheavy region is critical in investigating new elements beyond oganesson and the island of stability.This paper presents the application of a random forest algorithm to examine the competition among different decay modes in the superheavy region,includingα decay,β^(-)decay,β^(+)decay,electron capture and spontaneous fission.The observed half-lives and dominant decay mode are well reproduced.The dominant decay mode of 96.9%of the nuclei beyond ^(212) Po is correctly obtained.Further,α decay is predicted to be the dominant decay mode for isotopes in new elements Z=119-122,except for spontaneous fission in certain even–even elements owing to the increased Coulomb repulsion and odd–even effect.The predicted half-lives demonstrate the existence of a long-lived spontaneous fission island southwest of ^(298) Fl caused by the competition between the fission barrier and Coulomb repulsion.A better understanding of spontaneous fission,particularly beyond ^(286)Fl,is crucial in the search for new elements and the island of stability.展开更多
The binding and proton separation energies of nuclides with Z,N=30-50 are investigated based on the shell model,with an uncertainty analysis via statistical methods.Several formulas are used to obtain the binding and ...The binding and proton separation energies of nuclides with Z,N=30-50 are investigated based on the shell model,with an uncertainty analysis via statistical methods.Several formulas are used to obtain the binding and proton separation energies according to shell-model calculations.The non-parametric bootstrap method is applied to establish an uncertainty decomposition and recomposition framework.Moreover,this is used to estimate the stability of proton(s) emission for each nuclide.Two formulas for calculating the binding energies with a systematic uncertainty of~0.3 Me V are proposed,and a reliable extrapolation ability is examined.These binding energy formulas deduce similar forms for their respective S_(p) and S_(2 p) energies,which predict the extension of the nuclear boundary of this region.A good description of the binding and proton separation energies is provided.The one-and twoproton separation energies and partial half-lives of proton emission are predicted,thus revealing a new dripline.Furthermore,there are 30 unstable nuclides predicted to be bound against proton(s)-emission.These nuclear properties will be useful in nuclear astrophysics.展开更多
基金This work was supported by the National Natural Science Foundation of China(11872080)Beijing Natural Science Foundation(3192005)。
文摘A geometrically nonlinear topology optimization method for continuum structures is proposed based on the independent continuous mapping method.The stress constraint problem is studied due to the importance of structural strength in engineering applications.First,a topology optimization model is established for a lightweight structure with element stress as constraints.Second,the stress globalization method is adopted to convert local stress constraints into strain energy constraints,which overcomes the difficulties caused by local stress constraints,such as model establishment,sensitivity analysis,and massive solution calculations.Third,the sensitivity of the objective function and constraint function is analyzed,and the method of moving asymptotes is employed to solve the optimization model.In addition,the additive hyperelasticity technique is utilized to solve the numerical instability induced by structures undergoing large deformation.Numerical examples are given to validate the feasibility of the proposed method.The method provides a significant reference for geometrically nonlinear optimization design.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(No.2021B0301030006)computational resources from Sun Yat-Sen University and the National Supercomputer Center in Guangzhou.
文摘β-decay half-life and β-delayed neutron emission(βn) are of great importance in the development of basic science and industrial applications, such as nuclear physics and nuclear energy, where β--decay plays an important role. Many theoretical models have been proposed to describe β-decay half-lives, whereas the systematic study of βn is still rare. This study aimed to investigate β--decay half-lives and βn probabilities through analytical formulas and by comparing them with experimental data. Analytical formulas for β--decay properties have been proposed by considering prominent factors, that is, decay energy,odevity, and the shell effect. The bootstrap method was used to simultaneously evaluate the total uncertainty on calculations,which was composed of statistic and systematic uncertainties. β--decay half-lives, βn probabilities, and the corresponding uncertainties were evaluated for the neutron-rich region. The experimental half-lives were well reproduced. Additional predictions are also presented with theoretical uncertainties, which helps to better understand the disparity between the experimental and theoretical results.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research under Grant No. 2021B0301030006the computational resources from SYSU and the National Supercomputer Center in Guangzhou。
文摘Information on the decay process of nuclides in the superheavy region is critical in investigating new elements beyond oganesson and the island of stability.This paper presents the application of a random forest algorithm to examine the competition among different decay modes in the superheavy region,includingα decay,β^(-)decay,β^(+)decay,electron capture and spontaneous fission.The observed half-lives and dominant decay mode are well reproduced.The dominant decay mode of 96.9%of the nuclei beyond ^(212) Po is correctly obtained.Further,α decay is predicted to be the dominant decay mode for isotopes in new elements Z=119-122,except for spontaneous fission in certain even–even elements owing to the increased Coulomb repulsion and odd–even effect.The predicted half-lives demonstrate the existence of a long-lived spontaneous fission island southwest of ^(298) Fl caused by the competition between the fission barrier and Coulomb repulsion.A better understanding of spontaneous fission,particularly beyond ^(286)Fl,is crucial in the search for new elements and the island of stability.
基金Supported by the National Natural Science Foundation of China (11775316,11825504,11961141004)the Tip-top Scientific and Technical Innovative Youth Talents of Guangdong special support program (2016TQ03N575)the Guangdong Major Project of Basic and Applied Basic Research (2021B0301030006)。
文摘The binding and proton separation energies of nuclides with Z,N=30-50 are investigated based on the shell model,with an uncertainty analysis via statistical methods.Several formulas are used to obtain the binding and proton separation energies according to shell-model calculations.The non-parametric bootstrap method is applied to establish an uncertainty decomposition and recomposition framework.Moreover,this is used to estimate the stability of proton(s) emission for each nuclide.Two formulas for calculating the binding energies with a systematic uncertainty of~0.3 Me V are proposed,and a reliable extrapolation ability is examined.These binding energy formulas deduce similar forms for their respective S_(p) and S_(2 p) energies,which predict the extension of the nuclear boundary of this region.A good description of the binding and proton separation energies is provided.The one-and twoproton separation energies and partial half-lives of proton emission are predicted,thus revealing a new dripline.Furthermore,there are 30 unstable nuclides predicted to be bound against proton(s)-emission.These nuclear properties will be useful in nuclear astrophysics.
