Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring.However,there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fib...Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring.However,there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fibers,and the detailed mechanism of how embedded optical fibers affect the micromechanical behavior and damage failure processes within composite materials remains unclear.This paper presents a micromechanical simulation analysis of composite materials embedded with optical fibers.By constructing representative volume elements(RVEs)with randomly distributed reinforcing fibers,the optical fiber,the matrix,and the interface phase,the micromechanical behavior and damage evolution under transverse tensile and compressive loads are explored.The study finds that the presence of embedded optical fibers significantly influences the initiation and propagation of microscopic damage within the composites.Under transverse tension,the fiber-matrix interface cracks first,followed by plastic cracking in the matrix surrounding the fibers,forming micro-cracks.Eventually,these cracks connect with the debonded areas at the fiber-matrix interface to form a dominant crack that spans the entire model.Under transverse compression,plastic cracking first occurs in the resin surrounding the optical fibers,connecting with the interface debonding areas between the optical fibers and the matrix to form two parallel shear bands.Additionally,it is observed that the strength of the interface between the optical fiber and the matrix critically affects the simulation results.The simulated damage morphologies align closely with those observed using scanning electron microscopy(SEM).These findings offer theoretical insights that can inform the design and fabrication of smart composite materials with embedded optical fiber sensors for advanced structural health monitoring.展开更多
The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplec...The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in detail.This chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective model.The construction of the relevant shell-model representations of the Sp(12,R)group along this chain is considered for three nuclei with varying collective properties and from different mass regions.It is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belonging to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but organized in a different way into different SO(6)shells.This is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm operation.Although the SU_(pn)(3)multiplets withinυ<υ0 are not all Pauli forbidden,it is safe to discard them.The results obtained in the present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.展开更多
The early precipitation process of Ni（75）Al（14）Mo（11） alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and oc...The early precipitation process of Ni（75）Al（14）Mo（11） alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and occupation probability of the three kinds of atoms were investigated.It is indicated that the non-stoichiometric Ll0（Ⅰ/Ⅱ） phases are found in the precipitation process.With the temperature increasing,the appearance time of Ll0 is brought forward.The Ll0（Ⅱ） structure always precipitates earlier than the Ll0（Ⅰ） structure.Compared with lower temperature,higher temperature brings the formation time of Ll0 phase forward and makes Ll0 phase have a higher order degree.But lower temperature shortens the process time of the Ll0 phase to the Ll2 phase.Al and Mo atoms tend to occupy γ site,Ni atom tends to occupy a and β sites.At the same temperature,Al atom has stronger occupation ability than Mo atom in the same site.Ni,Al and Mo collectively form the composited Ll2 structure.展开更多
We present simulations of the mechanism of secondary nucleation of polymer crystallization,based on a new model accounting for the microscopic kinetics of attaching and detaching.As the key feature of the model,we int...We present simulations of the mechanism of secondary nucleation of polymer crystallization,based on a new model accounting for the microscopic kinetics of attaching and detaching.As the key feature of the model,we introduced multibody-interaction parameters that establish correlations between the attaching and detaching rate constants and the resulting thickness and width of the crystalline lamella.Using MATLAB and Monte Carlo method,we followed the evolution of the secondary nuclei as a function of various multibody-interaction parameters.We identified three different growth progressions of the crystal：（i） Widening,（ii） thickening and（iii） simultaneously thickening and widening of lamellar crystals,controlled by the corresponding kinetic parameters.展开更多
The microscopic global nucleon–nucleus optical model potential(OMP)proposed by Whitehead,Lim,and Holt,the WLH potential(Whitehead et al.,Phys Rev Lett 127:182502,2021),which was constructed in the framework of many-b...The microscopic global nucleon–nucleus optical model potential(OMP)proposed by Whitehead,Lim,and Holt,the WLH potential(Whitehead et al.,Phys Rev Lett 127:182502,2021),which was constructed in the framework of many-body per-turbation theory with state-of-the-art nuclear interactions from chiral effective field theory(EFT),was tested with(p,d)transfer reactions calculated using adiabatic wave approximation.The target nuclei included both stable and unstable nuclei,and the incident energies reached 200 MeV.The results were compared with experimental data and predictions using the phenomenological global optical potential of Koning and Delaroche,the KD02 potential.Overall,we found that the micro-scopic WLH potential described the(p,d)reaction angular distributions similarly to the phenomenological KD02 potential;however,the former was slightly better than the latter for radioactive targets.On average,the obtained spectroscopic factors(SFs)using both microscopic and phenomenological potentials were similar when the incident energies were below approxi-mately 120 MeV.However,their difference tended to increase at higher incident energies,which was particularly apparent for the doubly magic target nucleus 40Ca.展开更多
In this paper, we adopt the coarse graining method proposed by Lee H K et al. to develop a macroscopic model from the microscopic traffic model-GOVM. The proposed model inherits the parameter p which considers the inf...In this paper, we adopt the coarse graining method proposed by Lee H K et al. to develop a macroscopic model from the microscopic traffic model-GOVM. The proposed model inherits the parameter p which considers the influence of next-nearest car introduced in the GOVM model. The simulation results show that the new model is strictly consistent with the former microscopic model. Using this macroscopic model, we can avoid considering the details of each traffic on the road, and build more complex models such as road network model easily in the future.展开更多
As a cluster overlap amplitude,the reduced-width amplitude is an important physical quantity for analyzing clustering in the nucleus depending on specified channels and has been calculated and widely applied in nuclea...As a cluster overlap amplitude,the reduced-width amplitude is an important physical quantity for analyzing clustering in the nucleus depending on specified channels and has been calculated and widely applied in nuclear cluster physics.In this review,we briefly revisit the theoretical framework for calculating the reduced-width amplitude,as well as the outlines of cluster models to obtain microscopic or semi-microscopic cluster wave functions.We also introduce the recent progress related to cluster overlap amplitudes,including the implementation of cross-section estimation and extension to three-body clustering analysis.Comprehensive examples are provided to demonstrate the application of the reduced-width amplitude in analyzing clustering structures.展开更多
Symplectic symmetry approach to clustering(SSAC)in atomic nuclei,recently proposed,is modified and further developed in more detail.It is firstly applied to the light two-cluster^(20)Ne+αsystem of^(24)Mg,the latter e...Symplectic symmetry approach to clustering(SSAC)in atomic nuclei,recently proposed,is modified and further developed in more detail.It is firstly applied to the light two-cluster^(20)Ne+αsystem of^(24)Mg,the latter exhibiting well developed low-energy K^(π)=0_(1)^(+),k^(π)=2_(1)^(+) and π^(π)=0_(1)^(-) rotational bands in its spectrum.A simple algebraic Hamiltonian,consisting of dynamical symmetry,residual and vertical mixing parts is used to describe these three lowest rotational bands of positive and negative parity in^(24)Mg.A good description of the excitation energies is obtained by considering only the SU(3)cluster states restricted to the stretched many-particle Hilbert subspace,built on the leading Pauli allowed SU(3)multiplet for the positive-and negative-parity states,respectively.The coupling to the higher cluster-model configurations allows us to describe the known low-lying experimentally observed B(E2)transition probabilities within and between the cluster states of the three bands under consideration without the use of an effective charge.展开更多
The influence of temperature on the precipitation mechanism and sequence of L 12 and D022 phases during the early precipitation process of a Ni-15.Sat%Cr-14at%Al alloy was simulated based on the microscopic phase-fiel...The influence of temperature on the precipitation mechanism and sequence of L 12 and D022 phases during the early precipitation process of a Ni-15.Sat%Cr-14at%Al alloy was simulated based on the microscopic phase-field model. In the range from 873 to 1373 K, the precipitation mechanism transformed from spinodal decomposition to non-classic nucleation and growth; the incubation period prolonged gradually with increasing temperature. The volume fraction of L12 phases increased and that of D022 phases decreased. D022 phases disappeared at 1373 K, and finally single-phase L12 phases were formed.展开更多
The distinct element method（DEM） incorporated with a novel bond contact model was applied in this paper to shed light on the microscopic physical origin of macroscopic behaviors of weathered rock, and to achieve the...The distinct element method（DEM） incorporated with a novel bond contact model was applied in this paper to shed light on the microscopic physical origin of macroscopic behaviors of weathered rock, and to achieve the changing laws of microscopic parameters from observed decaying properties of rocks during weathering. The changing laws of macroscopic mechanical properties of typical rocks were summarized based on the existing research achievements. Parametric simulations were then conducted to analyze the relationships between macroscopic and microscopic parameters, and to derive the changing laws of microscopic parameters for the DEM model. Equipped with the microscopic weathering laws, a series of DEM simulations of basic laboratory tests on weathered rock samples was performed in comparison with analytical solutions. The results reveal that the relationships between macroscopic and microscopic parameters of rocks against the weathering period can be successfully attained by parametric simulations. In addition, weathering has a significant impact on both stressestrain relationship and failure pattern of rocks.展开更多
Simulations are performed on temporal evolution of atom morphology and ordering parameters of Ni-14.5 Cr-16.5 Al alloy during early precipitation process at different temperatures based on microscopic phase-field theo...Simulations are performed on temporal evolution of atom morphology and ordering parameters of Ni-14.5 Cr-16.5 Al alloy during early precipitation process at different temperatures based on microscopic phase-field theory; the relationship between precipitation sequence and mechanism of L12 and D022 structure and precipitation temperature are illuminated. The nonstoichiometric ordered L12 phases appear first with congruent ordering＋spinodal decomposition mechanism which is then followed by precipitation of D022 phases at ordering domain boundaries of L12 phases by spinodal decomposition mechanism at 1073 K and 1223 K. The nonstoichiometric L12 phases transform to stoichiometric ordering phases gradually. The incubation period of L12 and D022 phases is shorter at 1073 K than that 1223 K, and growth speed is higher at 1073 K. At 1373 K, L12 and D022 phases appear simultaneously by non-classical nucleation and growth mechanism. After that the particles of D022 phases diminish and disappear gradually; L12 phases grow and single L12 phases are remained at last.展开更多
In a multi-lane area,the increasing randomness of lane changes contributes to traffic insecurity and local traffic flow instability.A study on safe lane shifting activity that focuses on threat assessment under real-t...In a multi-lane area,the increasing randomness of lane changes contributes to traffic insecurity and local traffic flow instability.A study on safe lane shifting activity that focuses on threat assessment under real-time knowledge is necessary to enhance smooth vehicle flow.This paper proposed amore comprehensive lane changing guidance rule to investigate the status of surrounding vehicles to accommodate future vehicle-on-road collaborative environments based on these parameters 1)lane change demand and 2)treat assessment function.The collaborative relationships between vehicles are analyzed using a cellular automata model based on their location,velocity,and acceleration.We analyze and examine the relationship between the number of lanes and traffic flow when the road capacity is heavily mined via intelligent lane changing.Our analysis can further provide theoretical guidance for the selection of road expansion mode.Our proposed STCA-L is compared based on the average speed,average flow,lane changing frequency,spatial and temporal pattern of STCA,STCA-I,and STCA-S,and STCA-M under different vehicle densities.The numerical simulation results show that our proposed STCA-L provides themost flexible lane changing guidance in the multi-lanes road.Moreover,the simulated results show that the exponential growth of physical space cannot provide the corresponding increase in the average flow of vehicles.展开更多
The excellent performance of laser-induced removal has been widely recognized,yet the limitation of its applications has been gradually approached for complex multilayer coatings in practical situations.Therefore,it i...The excellent performance of laser-induced removal has been widely recognized,yet the limitation of its applications has been gradually approached for complex multilayer coatings in practical situations.Therefore,it is necessary to clarify the laser-induced removal mechanisms of different material layers,which may contribute to guiding precise and controllable layer-by-layer removal and subsequent repair.Herein,the laser-induced layer-by-layer removal of FeCo-based multilayer wave-absorbing coatings was designed and verified.The macro/micro morphologies and elemental analysis indicated that the removal of the topcoat and wave-absorbing layer was dominated by thermal ablation.Interestingly,experiments and simulations demonstrated that a shift in the removal mechanism,i.e.,from the ablation mechanism to the stripping mechanism,occurred when the laser irradiated the primer.It is mainly attributed to the competing contributions of temperature rise and thermal stress to the removal effect.Subsequent macrodynamic behavior captured by a high-speed camera also validated the combination of both re-moval mechanisms.Additionally,the evolution of the crystalline phase and element valence state was revealed.Further laser-induced breakdown spectroscopy revealed the microscopic material motions dur-ing the layer-by-layer removal,including molecular bond breaking induced by multiphoton absorption,atomic ionization,excitation and compounding of electrons and ions,crystal lattice deformation caused by electron-phonon coupling,etc.Based on the above analysis,the thermo-mechanical action mechanisms and microscopic motion models of laser-induced layer-by-layer removal for FeCo-based multilayer wave-absorbing coatings were established,which is expected to be an ideal method for breaking through the limitation of laser-induced removal’s applications.展开更多
The global nuclear mass based on the macroscopic-microscopic model was studied by applying a newly designed multi-task learning artificial neural network(MTL-ANN). First, the reported nuclear binding energies of 2095 ...The global nuclear mass based on the macroscopic-microscopic model was studied by applying a newly designed multi-task learning artificial neural network(MTL-ANN). First, the reported nuclear binding energies of 2095 nuclei(Z ≥ 8, N ≥ 8) released in the latest Atomic Mass Evaluation AME2020 and the deviations between the fitting result of the liquid drop model(LDM)and data from AME2020 for each nucleus were obtained.To compensate for the deviations and investigate the possible ignored physics in the LDM, the MTL-ANN method was introduced in the model. Compared to the single-task learning(STL) method, this new network has a powerful ability to simultaneously learn multi-nuclear properties,such as the binding energies and single neutron and proton separation energies. Moreover, it is highly effective in reducing the risk of overfitting and achieving better predictions. Consequently, good predictions can be obtained using this nuclear mass model for both the training and validation datasets and for the testing dataset. In detail, the global root mean square(RMS) of the binding energy is effectively reduced from approximately 2.4 MeV of LDM to the current 0.2 MeV, and the RMS of Sn, Spcan also reach approximately 0.2 MeV. Moreover, compared to STL, for the training and validation sets, 3-9% improvement can be achieved with the binding energy, and 20-30% improvement for S_(n), S_(p);for the testing sets, the reduction in deviations can even reach 30-40%, which significantly illustrates the advantage of the current MTL.展开更多
The structure properties for even–even nuclei around^(230)U,located on the hexadecapoledeformation island,are investigated using the potential-energy-surface calculation within the framework of the macroscopic-micros...The structure properties for even–even nuclei around^(230)U,located on the hexadecapoledeformation island,are investigated using the potential-energy-surface calculation within the framework of the macroscopic-microscopic model.The impact of different deformation degrees of freedom(including axial and nonaxial quadrupole and hexadecapole deformations)on total energy,shell,and pairing contributions is analyzed,based on the projected energy maps and curves.The single-particle structure is presented and briefly discussed.To a large extent,a much better agreement with experimental data and other theoretical results is obtained if the hexadecapole deformations,especially the axial one,are taken into account.These results could provide useful insights into understanding the effects of different quadrupole and hexadecapole deformations.展开更多
The pre-precipitation processes of γ＇ phase in Ni-Al-Ti alloy with different chemical compositions are investigated by microscopic phase-field dynamics model. The simulation results show that the early precip...The pre-precipitation processes of γ＇ phase in Ni-Al-Ti alloy with different chemical compositions are investigated by microscopic phase-field dynamics model. The simulation results show that the early precipitated phase with L10 structure is formed before the formation of γ＇ phase. With the increase of Al content, the composition of precipitated phase is transformed from the co-existence of γ＇ phase and material phase into single y phase. Furthermore, excessive Al content can stimulate the production of γ＇ phase, and the conversion time from L10 phase to L12 phase will lag behind other samples with lower Al con-tent. By analyzing the occupation probability of Ti, it can be found that the solid solution strengthening effect of Ti is reduced with the increase of Al component.展开更多
Tight sandstone reservoirs are characterized by complex pore structures and strong heterogeneity,and their seepage characteristics are much different from those of conventional sandstone reservoirs.In this paper,the t...Tight sandstone reservoirs are characterized by complex pore structures and strong heterogeneity,and their seepage characteristics are much different from those of conventional sandstone reservoirs.In this paper,the tight sandstone reservoirs of Upper Jurassic Penglaizhen Fm in western Sichuan Basin were analyzed in terms of their pore structures by using the data about physical property,mercury injection and nuclear magnetic resonance(NMR)tests.Then,the seepage characteristics and the gasewater two-phase migration mechanisms and distribution of tight sandstone reservoirs with different types of pore structures in the process of hydrocarbon accumulation and development were simulated by combining the relative permeability experiment with the visual microscopic displacement model.It is shown that crotch-like viscous fingering occurs in the process of gas front advancing in reservoirs with different pore structures.The better the pore structure is,the lower the irreducible water saturation is;the higher the gas-phase relative permeability of irreducible water is,the more easily the gas reservoir can be developed.At the late stage of development,the residual gas is sealed in reservoirs in the forms of bypass,cutoff and dead end.In various reservoirs,the interference between gas and water is stronger,so gas and water tends to be produced simultaneously.The sealed gas may reduce the production rate of gas wells significantly,and the existence of water phase may reduce the gas permeability greatly;consequently,the water-bearing low-permeability tight sandstone gas reservoirs reveal serious water production,highly-difficult development and low-recovery percentage at the late stage,which have adverse impacts on the effective production and development of gas wells.展开更多
Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical...Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and ~reater seismic safety.展开更多
To study the effect of tempering temperature on strain hardening exponent and flow stress curve,one kind of 1000 MPa grade low carbon bainitic steel for construction machinery was designed,and the standard uniaxial te...To study the effect of tempering temperature on strain hardening exponent and flow stress curve,one kind of 1000 MPa grade low carbon bainitic steel for construction machinery was designed,and the standard uniaxial tensile tests were conducted at room temperature.A new flow stress model,which could predict the flow behavior of the tested steels at different tempering temperatures more efficiently,was established.The relationship between mobile dislocation density and strain hardening exponent was discussed based on the dislocation-stress relation.Arrhenius equation and an inverse proportional function were adopted to describe the mobile dislocation,and two mathematical models were established to describe the relationship between tempering temperature and strain hardening exponent.Nonlinear regression analysis was applied to the Arrhenius type model,hence,the activation energy was determined to be 37.6kJ/mol.Moreover,the square of correlation coefficient was 0.985,which indicated a high reliability between the fitted curve and experimental data.By comparison with the Arrhenius type curve,the general trend of the inverse proportional fitting curve was coincided with the experimental data points except of some fitting errors.Thus,the Arrhenius type model can be adopted to predict the strain hardening exponent at different tempering temperatures.展开更多
Crowd evacuation simulation is an essential element when it comes to planning and preparation in evacuation management.This paper presents the survey based on systematic literature review(SLR)technique that aims to id...Crowd evacuation simulation is an essential element when it comes to planning and preparation in evacuation management.This paper presents the survey based on systematic literature review(SLR)technique that aims to identify the crowd evacuation under microscopic model integrated with soft computing technique from previous works.In the review process,renowned databases were searched to retrieve the primary articles and total 38 studies were thoroughly studied.The researcher has identified the potential optimization factors in simulating crowd evacuation and research gaps based on acquired issues,limitation and challenges in this domain.The results of this SLR will serve as a guideline for the researchers that have same interest to develop better and effective crowd evacuation simulation model.The future direction from this SLR also suggests that there is a potential to hybrid the model with softcomputing optimization focusing on latest nature-inspired algorithms in improving the crowd evacuation model.展开更多
基金funded by the National Key Research and Development Program of China(Grant No.2022YFB3402500)the National Natural Science Foundation of China(Grant No.12372129).
文摘Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring.However,there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fibers,and the detailed mechanism of how embedded optical fibers affect the micromechanical behavior and damage failure processes within composite materials remains unclear.This paper presents a micromechanical simulation analysis of composite materials embedded with optical fibers.By constructing representative volume elements(RVEs)with randomly distributed reinforcing fibers,the optical fiber,the matrix,and the interface phase,the micromechanical behavior and damage evolution under transverse tensile and compressive loads are explored.The study finds that the presence of embedded optical fibers significantly influences the initiation and propagation of microscopic damage within the composites.Under transverse tension,the fiber-matrix interface cracks first,followed by plastic cracking in the matrix surrounding the fibers,forming micro-cracks.Eventually,these cracks connect with the debonded areas at the fiber-matrix interface to form a dominant crack that spans the entire model.Under transverse compression,plastic cracking first occurs in the resin surrounding the optical fibers,connecting with the interface debonding areas between the optical fibers and the matrix to form two parallel shear bands.Additionally,it is observed that the strength of the interface between the optical fiber and the matrix critically affects the simulation results.The simulated damage morphologies align closely with those observed using scanning electron microscopy(SEM).These findings offer theoretical insights that can inform the design and fabrication of smart composite materials with embedded optical fiber sensors for advanced structural health monitoring.
文摘The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in detail.This chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective model.The construction of the relevant shell-model representations of the Sp(12,R)group along this chain is considered for three nuclei with varying collective properties and from different mass regions.It is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belonging to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but organized in a different way into different SO(6)shells.This is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm operation.Although the SU_(pn)(3)multiplets withinυ<υ0 are not all Pauli forbidden,it is safe to discard them.The results obtained in the present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.
基金Project(51275486)supported by the National Natural Science Foundation of China
文摘The early precipitation process of Ni（75）Al（14）Mo（11） alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and occupation probability of the three kinds of atoms were investigated.It is indicated that the non-stoichiometric Ll0（Ⅰ/Ⅱ） phases are found in the precipitation process.With the temperature increasing,the appearance time of Ll0 is brought forward.The Ll0（Ⅱ） structure always precipitates earlier than the Ll0（Ⅰ） structure.Compared with lower temperature,higher temperature brings the formation time of Ll0 phase forward and makes Ll0 phase have a higher order degree.But lower temperature shortens the process time of the Ll0 phase to the Ll2 phase.Al and Mo atoms tend to occupy γ site,Ni atom tends to occupy a and β sites.At the same temperature,Al atom has stronger occupation ability than Mo atom in the same site.Ni,Al and Mo collectively form the composited Ll2 structure.
基金financially supported by the National Natural Science Foundation of China(No.21374054)the Sino-German Center for Research Promotion
文摘We present simulations of the mechanism of secondary nucleation of polymer crystallization,based on a new model accounting for the microscopic kinetics of attaching and detaching.As the key feature of the model,we introduced multibody-interaction parameters that establish correlations between the attaching and detaching rate constants and the resulting thickness and width of the crystalline lamella.Using MATLAB and Monte Carlo method,we followed the evolution of the secondary nuclei as a function of various multibody-interaction parameters.We identified three different growth progressions of the crystal：（i） Widening,（ii） thickening and（iii） simultaneously thickening and widening of lamellar crystals,controlled by the corresponding kinetic parameters.
基金Supported by National Natural Science Foundation of China(Nos.U2067205 and 12205098)National Key Laboratory of Computational Physics(HX02021-35).
文摘The microscopic global nucleon–nucleus optical model potential(OMP)proposed by Whitehead,Lim,and Holt,the WLH potential(Whitehead et al.,Phys Rev Lett 127:182502,2021),which was constructed in the framework of many-body per-turbation theory with state-of-the-art nuclear interactions from chiral effective field theory(EFT),was tested with(p,d)transfer reactions calculated using adiabatic wave approximation.The target nuclei included both stable and unstable nuclei,and the incident energies reached 200 MeV.The results were compared with experimental data and predictions using the phenomenological global optical potential of Koning and Delaroche,the KD02 potential.Overall,we found that the micro-scopic WLH potential described the(p,d)reaction angular distributions similarly to the phenomenological KD02 potential;however,the former was slightly better than the latter for radioactive targets.On average,the obtained spectroscopic factors(SFs)using both microscopic and phenomenological potentials were similar when the incident energies were below approxi-mately 120 MeV.However,their difference tended to increase at higher incident energies,which was particularly apparent for the doubly magic target nucleus 40Ca.
基金Project supported by National Creative Research Groups Science Foundation of China(Grant No.60721062)National Basic Research Program of China(Grant No.2007CB714000)
文摘In this paper, we adopt the coarse graining method proposed by Lee H K et al. to develop a macroscopic model from the microscopic traffic model-GOVM. The proposed model inherits the parameter p which considers the influence of next-nearest car introduced in the GOVM model. The simulation results show that the new model is strictly consistent with the former microscopic model. Using this macroscopic model, we can avoid considering the details of each traffic on the road, and build more complex models such as road network model easily in the future.
基金supported by the National Key R&D Program of China(No.2023YFA1606701)the National Natural Science Foundation of China(Nos.12175042 and 12147101)。
文摘As a cluster overlap amplitude,the reduced-width amplitude is an important physical quantity for analyzing clustering in the nucleus depending on specified channels and has been calculated and widely applied in nuclear cluster physics.In this review,we briefly revisit the theoretical framework for calculating the reduced-width amplitude,as well as the outlines of cluster models to obtain microscopic or semi-microscopic cluster wave functions.We also introduce the recent progress related to cluster overlap amplitudes,including the implementation of cross-section estimation and extension to three-body clustering analysis.Comprehensive examples are provided to demonstrate the application of the reduced-width amplitude in analyzing clustering structures.
文摘Symplectic symmetry approach to clustering(SSAC)in atomic nuclei,recently proposed,is modified and further developed in more detail.It is firstly applied to the light two-cluster^(20)Ne+αsystem of^(24)Mg,the latter exhibiting well developed low-energy K^(π)=0_(1)^(+),k^(π)=2_(1)^(+) and π^(π)=0_(1)^(-) rotational bands in its spectrum.A simple algebraic Hamiltonian,consisting of dynamical symmetry,residual and vertical mixing parts is used to describe these three lowest rotational bands of positive and negative parity in^(24)Mg.A good description of the excitation energies is obtained by considering only the SU(3)cluster states restricted to the stretched many-particle Hilbert subspace,built on the leading Pauli allowed SU(3)multiplet for the positive-and negative-parity states,respectively.The coupling to the higher cluster-model configurations allows us to describe the known low-lying experimentally observed B(E2)transition probabilities within and between the cluster states of the three bands under consideration without the use of an effective charge.
基金This work was financially supported by the National Natural Science Foundation of China (No.50071046) and the National High-Tech Research and Development Program of China (No.2002AA331051).
文摘The influence of temperature on the precipitation mechanism and sequence of L 12 and D022 phases during the early precipitation process of a Ni-15.Sat%Cr-14at%Al alloy was simulated based on the microscopic phase-field model. In the range from 873 to 1373 K, the precipitation mechanism transformed from spinodal decomposition to non-classic nucleation and growth; the incubation period prolonged gradually with increasing temperature. The volume fraction of L12 phases increased and that of D022 phases decreased. D022 phases disappeared at 1373 K, and finally single-phase L12 phases were formed.
基金funded by the National Basic Research Programs of China(Grant Nos.2011CB013504 and 2014CB046901)the National Funds for Distinguished Young Scientists of China(Grant No.51025932)the National Nature Science Foundation of China(Grant No.41372272)
文摘The distinct element method（DEM） incorporated with a novel bond contact model was applied in this paper to shed light on the microscopic physical origin of macroscopic behaviors of weathered rock, and to achieve the changing laws of microscopic parameters from observed decaying properties of rocks during weathering. The changing laws of macroscopic mechanical properties of typical rocks were summarized based on the existing research achievements. Parametric simulations were then conducted to analyze the relationships between macroscopic and microscopic parameters, and to derive the changing laws of microscopic parameters for the DEM model. Equipped with the microscopic weathering laws, a series of DEM simulations of basic laboratory tests on weathered rock samples was performed in comparison with analytical solutions. The results reveal that the relationships between macroscopic and microscopic parameters of rocks against the weathering period can be successfully attained by parametric simulations. In addition, weathering has a significant impact on both stressestrain relationship and failure pattern of rocks.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 50071046） the National High-Tech Research and Development Program of China （863 Program, No. 2002AA331051）.
文摘Simulations are performed on temporal evolution of atom morphology and ordering parameters of Ni-14.5 Cr-16.5 Al alloy during early precipitation process at different temperatures based on microscopic phase-field theory; the relationship between precipitation sequence and mechanism of L12 and D022 structure and precipitation temperature are illuminated. The nonstoichiometric ordered L12 phases appear first with congruent ordering＋spinodal decomposition mechanism which is then followed by precipitation of D022 phases at ordering domain boundaries of L12 phases by spinodal decomposition mechanism at 1073 K and 1223 K. The nonstoichiometric L12 phases transform to stoichiometric ordering phases gradually. The incubation period of L12 and D022 phases is shorter at 1073 K than that 1223 K, and growth speed is higher at 1073 K. At 1373 K, L12 and D022 phases appear simultaneously by non-classical nucleation and growth mechanism. After that the particles of D022 phases diminish and disappear gradually; L12 phases grow and single L12 phases are remained at last.
基金supported in part by the National Natural Science Foundation of China(No.51905405)Basic Research Program of Natural Science of Shaanxi Province(No.2022JM-407)Guiding Program of Science and Technology of China Textile Industry Federation(No.2020106).
文摘In a multi-lane area,the increasing randomness of lane changes contributes to traffic insecurity and local traffic flow instability.A study on safe lane shifting activity that focuses on threat assessment under real-time knowledge is necessary to enhance smooth vehicle flow.This paper proposed amore comprehensive lane changing guidance rule to investigate the status of surrounding vehicles to accommodate future vehicle-on-road collaborative environments based on these parameters 1)lane change demand and 2)treat assessment function.The collaborative relationships between vehicles are analyzed using a cellular automata model based on their location,velocity,and acceleration.We analyze and examine the relationship between the number of lanes and traffic flow when the road capacity is heavily mined via intelligent lane changing.Our analysis can further provide theoretical guidance for the selection of road expansion mode.Our proposed STCA-L is compared based on the average speed,average flow,lane changing frequency,spatial and temporal pattern of STCA,STCA-I,and STCA-S,and STCA-M under different vehicle densities.The numerical simulation results show that our proposed STCA-L provides themost flexible lane changing guidance in the multi-lanes road.Moreover,the simulated results show that the exponential growth of physical space cannot provide the corresponding increase in the average flow of vehicles.
基金support from the National Natural Science Foundation of China(Nos.52075246 and U2341264)the Natural Science Foundation of Jiangsu Province(Nos.BK20211568 and BZ2023045)+2 种基金National Science and Technology Major Project of China(No.J2019-Ⅲ-0010-0054)Fundamental Research Funds for the Central Universities(No.NE2022005)Liaoning Provincial Key Laboratory of Aircraft Ice Protection(No.XFX20220301).
文摘The excellent performance of laser-induced removal has been widely recognized,yet the limitation of its applications has been gradually approached for complex multilayer coatings in practical situations.Therefore,it is necessary to clarify the laser-induced removal mechanisms of different material layers,which may contribute to guiding precise and controllable layer-by-layer removal and subsequent repair.Herein,the laser-induced layer-by-layer removal of FeCo-based multilayer wave-absorbing coatings was designed and verified.The macro/micro morphologies and elemental analysis indicated that the removal of the topcoat and wave-absorbing layer was dominated by thermal ablation.Interestingly,experiments and simulations demonstrated that a shift in the removal mechanism,i.e.,from the ablation mechanism to the stripping mechanism,occurred when the laser irradiated the primer.It is mainly attributed to the competing contributions of temperature rise and thermal stress to the removal effect.Subsequent macrodynamic behavior captured by a high-speed camera also validated the combination of both re-moval mechanisms.Additionally,the evolution of the crystalline phase and element valence state was revealed.Further laser-induced breakdown spectroscopy revealed the microscopic material motions dur-ing the layer-by-layer removal,including molecular bond breaking induced by multiphoton absorption,atomic ionization,excitation and compounding of electrons and ions,crystal lattice deformation caused by electron-phonon coupling,etc.Based on the above analysis,the thermo-mechanical action mechanisms and microscopic motion models of laser-induced layer-by-layer removal for FeCo-based multilayer wave-absorbing coatings were established,which is expected to be an ideal method for breaking through the limitation of laser-induced removal’s applications.
基金supported by the National Natural Science Foundation of China(Nos.1187050492,12005303,and 12175170).
文摘The global nuclear mass based on the macroscopic-microscopic model was studied by applying a newly designed multi-task learning artificial neural network(MTL-ANN). First, the reported nuclear binding energies of 2095 nuclei(Z ≥ 8, N ≥ 8) released in the latest Atomic Mass Evaluation AME2020 and the deviations between the fitting result of the liquid drop model(LDM)and data from AME2020 for each nucleus were obtained.To compensate for the deviations and investigate the possible ignored physics in the LDM, the MTL-ANN method was introduced in the model. Compared to the single-task learning(STL) method, this new network has a powerful ability to simultaneously learn multi-nuclear properties,such as the binding energies and single neutron and proton separation energies. Moreover, it is highly effective in reducing the risk of overfitting and achieving better predictions. Consequently, good predictions can be obtained using this nuclear mass model for both the training and validation datasets and for the testing dataset. In detail, the global root mean square(RMS) of the binding energy is effectively reduced from approximately 2.4 MeV of LDM to the current 0.2 MeV, and the RMS of Sn, Spcan also reach approximately 0.2 MeV. Moreover, compared to STL, for the training and validation sets, 3-9% improvement can be achieved with the binding energy, and 20-30% improvement for S_(n), S_(p);for the testing sets, the reduction in deviations can even reach 30-40%, which significantly illustrates the advantage of the current MTL.
基金the National Natural Science Foundation of China(No.11975209,No.U2032211,and No.12075287)the Physics Research and Development Program of Zhengzhou University(No.32410017)the Project of Youth Backbone Teachers of Colleges and Universities of Henan Province(No.2017GGJS008)
文摘The structure properties for even–even nuclei around^(230)U,located on the hexadecapoledeformation island,are investigated using the potential-energy-surface calculation within the framework of the macroscopic-microscopic model.The impact of different deformation degrees of freedom(including axial and nonaxial quadrupole and hexadecapole deformations)on total energy,shell,and pairing contributions is analyzed,based on the projected energy maps and curves.The single-particle structure is presented and briefly discussed.To a large extent,a much better agreement with experimental data and other theoretical results is obtained if the hexadecapole deformations,especially the axial one,are taken into account.These results could provide useful insights into understanding the effects of different quadrupole and hexadecapole deformations.
基金National Natural Science Foundation of China(Nos.U1610123,51674226,51574207,51574206,51274175)International Cooperation Project of the Ministry of Science and Technology of China(No.2014DFA50320)Science and Technology Major Project of Shanxi Province(No.MC2016-06)
文摘The pre-precipitation processes of γ＇ phase in Ni-Al-Ti alloy with different chemical compositions are investigated by microscopic phase-field dynamics model. The simulation results show that the early precipitated phase with L10 structure is formed before the formation of γ＇ phase. With the increase of Al content, the composition of precipitated phase is transformed from the co-existence of γ＇ phase and material phase into single y phase. Furthermore, excessive Al content can stimulate the production of γ＇ phase, and the conversion time from L10 phase to L12 phase will lag behind other samples with lower Al con-tent. By analyzing the occupation probability of Ti, it can be found that the solid solution strengthening effect of Ti is reduced with the increase of Al component.
文摘Tight sandstone reservoirs are characterized by complex pore structures and strong heterogeneity,and their seepage characteristics are much different from those of conventional sandstone reservoirs.In this paper,the tight sandstone reservoirs of Upper Jurassic Penglaizhen Fm in western Sichuan Basin were analyzed in terms of their pore structures by using the data about physical property,mercury injection and nuclear magnetic resonance(NMR)tests.Then,the seepage characteristics and the gasewater two-phase migration mechanisms and distribution of tight sandstone reservoirs with different types of pore structures in the process of hydrocarbon accumulation and development were simulated by combining the relative permeability experiment with the visual microscopic displacement model.It is shown that crotch-like viscous fingering occurs in the process of gas front advancing in reservoirs with different pore structures.The better the pore structure is,the lower the irreducible water saturation is;the higher the gas-phase relative permeability of irreducible water is,the more easily the gas reservoir can be developed.At the late stage of development,the residual gas is sealed in reservoirs in the forms of bypass,cutoff and dead end.In various reservoirs,the interference between gas and water is stronger,so gas and water tends to be produced simultaneously.The sealed gas may reduce the production rate of gas wells significantly,and the existence of water phase may reduce the gas permeability greatly;consequently,the water-bearing low-permeability tight sandstone gas reservoirs reveal serious water production,highly-difficult development and low-recovery percentage at the late stage,which have adverse impacts on the effective production and development of gas wells.
基金supported by the research program of the National Dam Safety Research Center (Grants No.2011NDS021 and NDSKFJJ1103)the open fund of the State Key Laboratory of Hydraulics and Mountain River Engineering of Sichuan University (Grant No. 0912)the China Postdoctoral Science Foundation (Grant No. 2012M511594)
文摘Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and ~reater seismic safety.
文摘To study the effect of tempering temperature on strain hardening exponent and flow stress curve,one kind of 1000 MPa grade low carbon bainitic steel for construction machinery was designed,and the standard uniaxial tensile tests were conducted at room temperature.A new flow stress model,which could predict the flow behavior of the tested steels at different tempering temperatures more efficiently,was established.The relationship between mobile dislocation density and strain hardening exponent was discussed based on the dislocation-stress relation.Arrhenius equation and an inverse proportional function were adopted to describe the mobile dislocation,and two mathematical models were established to describe the relationship between tempering temperature and strain hardening exponent.Nonlinear regression analysis was applied to the Arrhenius type model,hence,the activation energy was determined to be 37.6kJ/mol.Moreover,the square of correlation coefficient was 0.985,which indicated a high reliability between the fitted curve and experimental data.By comparison with the Arrhenius type curve,the general trend of the inverse proportional fitting curve was coincided with the experimental data points except of some fitting errors.Thus,the Arrhenius type model can be adopted to predict the strain hardening exponent at different tempering temperatures.
基金This work was supported by Fundamental Research Grant Scheme(Ministry of Higher Edu-cation Malaysia):[Grant Number FRGS/1/2019/ICT02/UTM/02/13].
文摘Crowd evacuation simulation is an essential element when it comes to planning and preparation in evacuation management.This paper presents the survey based on systematic literature review(SLR)technique that aims to identify the crowd evacuation under microscopic model integrated with soft computing technique from previous works.In the review process,renowned databases were searched to retrieve the primary articles and total 38 studies were thoroughly studied.The researcher has identified the potential optimization factors in simulating crowd evacuation and research gaps based on acquired issues,limitation and challenges in this domain.The results of this SLR will serve as a guideline for the researchers that have same interest to develop better and effective crowd evacuation simulation model.The future direction from this SLR also suggests that there is a potential to hybrid the model with softcomputing optimization focusing on latest nature-inspired algorithms in improving the crowd evacuation model.
