Material identification is critical for understanding the relationship between mechanical properties and the associated mechanical functions.However,material identification is a challenging task,especially when the ch...Material identification is critical for understanding the relationship between mechanical properties and the associated mechanical functions.However,material identification is a challenging task,especially when the characteristic of the material is highly nonlinear in nature,as is common in biological tissue.In this work,we identify unknown material properties in continuum solid mechanics via physics-informed neural networks(PINNs).To improve the accuracy and efficiency of PINNs,we develop efficient strategies to nonuniformly sample observational data.We also investigate different approaches to enforce Dirichlet-type boundary conditions(BCs)as soft or hard constraints.Finally,we apply the proposed methods to a diverse set of time-dependent and time-independent solid mechanic examples that span linear elastic and hyperelastic material space.The estimated material parameters achieve relative errors of less than 1%.As such,this work is relevant to diverse applications,including optimizing structural integrity and developing novel materials.展开更多
In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic s...In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic simulations for modeling biological phenomena are discussed. CG particle models can largely increase the length scale and time scale of atomistic simulations by eliminating the fast degrees of freedom while preserving the mesoscopic structures and properties of the simulated system. Moreover, CG particle models can be used to capture the microstructural alternations in diseased RBCs and simulate the topological changes of biomembranes and RBCs, which are the major challenges to the typical continuum representations of membranes and RBCs. The power and versatility of CG particle methods are demonstrated：through simulating the dynamical processes mvolving significant topological .changes e.g. lipid self-assembly vesicle fusion and membrane budding.展开更多
Shock compression and spallation of a eutectic high-entropy alloy(HEA)AlCoCrFeNi_(2.1)with lamellar structure are investigated via plate impact loading with free-surface velocity measurements.The as-cast and postmorte...Shock compression and spallation of a eutectic high-entropy alloy(HEA)AlCoCrFeNi_(2.1)with lamellar structure are investigated via plate impact loading with free-surface velocity measurements.The as-cast and postmortem samples are characterized with transmission electron microscopy,electron back-scatter diffraction and scanning electron microscopy.An accurate Hugoniot equation of state is determined.Af-ter shock compression to∼12 GPa,both the L1_(2)and B_(2)phases retain their ordered structures.Dense dislocations in the{111}slip planes,stacking faults and deformation twins are found in the L1_(2)phase,along with fewer dislocations in the{110}slip bands in the B(2)phase.Shock-induced deformation twin-ning within the L1_(2)phase of this HEA is observed as a new deformation mechanism under various load-ing conditions.For spallation,both ductile and brittle damage modes are observed.The micro voids and cracks prefer to nucleate at the phase boundaries chiefly,then in the B(2)phase.Under similar shock stress,the spall strength of AlCoCrFeNi_(2.1)HEA is about 40%higher than those of other reported dual-phase HEAs due to the high stability of its semi-coherent phase boundaries.展开更多
Shock compression and spallation damage of a face-center cubic phase high-entropy alloy(HEA)Al_(0.1)CoCrFeNi were investigated via plate impact experiments along with free surface velocity measurements.Postmortem samp...Shock compression and spallation damage of a face-center cubic phase high-entropy alloy(HEA)Al_(0.1)CoCrFeNi were investigated via plate impact experiments along with free surface velocity measurements.Postmortem samples were characterized with transmission electron microscopy and electron backscatter diffraction.The Hugoniot equation of state and spall strength at different impact strengths were determined.There exists a power-law relation between spall strength and strain rate.The spall strength of Al_(0.1)CoCrFeNi HEA is about 50%higher than those of previously studied HEAs and comparable to those widely applied structural stainless steels at the same shock stress.Dislocation glide and stacking faults are the important deformation mechanisms in the Al_(0.1)CoCrFeNi HEA.Nanotwins are only observed at high shock stress.Damage in the Al_(0.1)CoCrFeNi HEA is ductile in nature.Voids are nucleated preferentially in grain interiors,and the intragranular voids show a strong dependence on grain boundary misorientation and peak stress.展开更多
Improving the thermal insulation of glazing units is a common strategy of reducing building energy use for spacing cooling.This paper newly examined the application of aerogel glazing technology in Hong Kong by the me...Improving the thermal insulation of glazing units is a common strategy of reducing building energy use for spacing cooling.This paper newly examined the application of aerogel glazing technology in Hong Kong by the means of laboratory testing and simulation.Nine prototypes of granular aerogel glazing were selected to examine their optical properties,and the measured optical properties of aerogel were used to calculate the total window thermal performance indices.A typical 40-story commercial office building was chosen for energy simulation to compare the thermal performance of aerogel glazing with different glazing technologies in Hong Kong.The results showed that aerogel glazing could achieve the promising reduction of window heat gain up to 57%and cooling energy up to 8.5%compared with double glazing.The heat insulation performance of aerogel glazing is even better than the double glazing with low-E coating in Hong Kong.Therefore,aerogel glazing can be a good alternative of glazing to comply with the existing local Overall Thermal Transfer Value(OTTV)requirement and to reduce the building energy use for space cooling in Hong Kong and other regions.展开更多
Heavy ion collisions near the Fermi energy produce a‘freezout’region where fragments appear and later decay,emitting mainly neutrons,protons,alpha particles,and gamma rays.These decay products carry information abou...Heavy ion collisions near the Fermi energy produce a‘freezout’region where fragments appear and later decay,emitting mainly neutrons,protons,alpha particles,and gamma rays.These decay products carry information about the decaying nuclei.Fragmentation events may result in high yields of boson particles,especially alpha particles,and may carry important information about the nuclear Bose Einstein condensate(BEC).We study‘in medium’fourαcorrelations and link them to the‘fission’of 16O in two 8Be in the ground state or 12C*(Hoyle state)+α.Using novel techniques for the correlation functions,we confirm the resonance of 16O at 15.2 MeV excitation energy,and the possibility of a lower resonance,close to 14.72 MeV.The latter resonance is the result of allαparticles having 92 keV relative kinetic energies.展开更多
基金funded by the Cora Topolewski Cardiac Research Fund at the Children’s Hospital of Philadelphia(CHOP)the Pediatric Valve Center Frontier Program at CHOP+4 种基金the Additional Ventures Single Ventricle Research Fund Expansion Awardthe National Institutes of Health(USA)supported by the program(Nos.NHLBI T32 HL007915 and NIH R01 HL153166)supported by the program(No.NIH R01 HL153166)supported by the U.S.Department of Energy(No.DE-SC0022953)。
文摘Material identification is critical for understanding the relationship between mechanical properties and the associated mechanical functions.However,material identification is a challenging task,especially when the characteristic of the material is highly nonlinear in nature,as is common in biological tissue.In this work,we identify unknown material properties in continuum solid mechanics via physics-informed neural networks(PINNs).To improve the accuracy and efficiency of PINNs,we develop efficient strategies to nonuniformly sample observational data.We also investigate different approaches to enforce Dirichlet-type boundary conditions(BCs)as soft or hard constraints.Finally,we apply the proposed methods to a diverse set of time-dependent and time-independent solid mechanic examples that span linear elastic and hyperelastic material space.The estimated material parameters achieve relative errors of less than 1%.As such,this work is relevant to diverse applications,including optimizing structural integrity and developing novel materials.
基金Project supported by the National Institutes of Health of U.S.A.(No.U01HL114476)the National Science Foundation of U.S.A.(Nos.CMMI-1235025 and PHY-1205910)
文摘In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic simulations for modeling biological phenomena are discussed. CG particle models can largely increase the length scale and time scale of atomistic simulations by eliminating the fast degrees of freedom while preserving the mesoscopic structures and properties of the simulated system. Moreover, CG particle models can be used to capture the microstructural alternations in diseased RBCs and simulate the topological changes of biomembranes and RBCs, which are the major challenges to the typical continuum representations of membranes and RBCs. The power and versatility of CG particle methods are demonstrated：through simulating the dynamical processes mvolving significant topological .changes e.g. lipid self-assembly vesicle fusion and membrane budding.
基金sponsored in part by Sichuan Province Key R&D Program(No.2022YFG0033)the National Natural Science Foundation of China(Nos.12102491,52101150,11902274,11627901).
文摘Shock compression and spallation of a eutectic high-entropy alloy(HEA)AlCoCrFeNi_(2.1)with lamellar structure are investigated via plate impact loading with free-surface velocity measurements.The as-cast and postmortem samples are characterized with transmission electron microscopy,electron back-scatter diffraction and scanning electron microscopy.An accurate Hugoniot equation of state is determined.Af-ter shock compression to∼12 GPa,both the L1_(2)and B_(2)phases retain their ordered structures.Dense dislocations in the{111}slip planes,stacking faults and deformation twins are found in the L1_(2)phase,along with fewer dislocations in the{110}slip bands in the B(2)phase.Shock-induced deformation twin-ning within the L1_(2)phase of this HEA is observed as a new deformation mechanism under various load-ing conditions.For spallation,both ductile and brittle damage modes are observed.The micro voids and cracks prefer to nucleate at the phase boundaries chiefly,then in the B(2)phase.Under similar shock stress,the spall strength of AlCoCrFeNi_(2.1)HEA is about 40%higher than those of other reported dual-phase HEAs due to the high stability of its semi-coherent phase boundaries.
基金financially supported in part by the Sichuan Province Key R&D Program(No.2022YFG0033)the National Natural Science Foundation of China(Nos.11627901 and11902274)。
文摘Shock compression and spallation damage of a face-center cubic phase high-entropy alloy(HEA)Al_(0.1)CoCrFeNi were investigated via plate impact experiments along with free surface velocity measurements.Postmortem samples were characterized with transmission electron microscopy and electron backscatter diffraction.The Hugoniot equation of state and spall strength at different impact strengths were determined.There exists a power-law relation between spall strength and strain rate.The spall strength of Al_(0.1)CoCrFeNi HEA is about 50%higher than those of previously studied HEAs and comparable to those widely applied structural stainless steels at the same shock stress.Dislocation glide and stacking faults are the important deformation mechanisms in the Al_(0.1)CoCrFeNi HEA.Nanotwins are only observed at high shock stress.Damage in the Al_(0.1)CoCrFeNi HEA is ductile in nature.Voids are nucleated preferentially in grain interiors,and the intragranular voids show a strong dependence on grain boundary misorientation and peak stress.
基金The work is financially supported by the Hong Kong Polytech-nic University through Mainland University Joint Supervision Scheme(G-SB0N)for their partial financial support.
文摘Improving the thermal insulation of glazing units is a common strategy of reducing building energy use for spacing cooling.This paper newly examined the application of aerogel glazing technology in Hong Kong by the means of laboratory testing and simulation.Nine prototypes of granular aerogel glazing were selected to examine their optical properties,and the measured optical properties of aerogel were used to calculate the total window thermal performance indices.A typical 40-story commercial office building was chosen for energy simulation to compare the thermal performance of aerogel glazing with different glazing technologies in Hong Kong.The results showed that aerogel glazing could achieve the promising reduction of window heat gain up to 57%and cooling energy up to 8.5%compared with double glazing.The heat insulation performance of aerogel glazing is even better than the double glazing with low-E coating in Hong Kong.Therefore,aerogel glazing can be a good alternative of glazing to comply with the existing local Overall Thermal Transfer Value(OTTV)requirement and to reduce the building energy use for space cooling in Hong Kong and other regions.
基金Supported by the National Natural Science Foundation of China(11765014,11865010,11905120,I1605097,U2032146,11421505)the Robert A.Welch Founda-tion(A-1266)+6 种基金the US Department of Energy(DE-FG02-93ER40773)Natural Science Foundation of Inner Mongolia(2018MS01009,20191001)the Chinese Academy of Sciences(CAS)President's International Fellowship Initiative(2015VW A070)the Strategic Priority Research Program of the Chinese Academy of Sci-ences(XDB16,XDPB09)the Program for Young Talents of Science and Technology in Univrities of Inmer Mongolia Autonomous Region(NJYT-18-B21)the Doctoral Seientifie Research Foundation of Inner Mongolia University for Nationalities(BS365.BS400)The Fundamental Research Funds for the Central University(GK201903022)。
文摘Heavy ion collisions near the Fermi energy produce a‘freezout’region where fragments appear and later decay,emitting mainly neutrons,protons,alpha particles,and gamma rays.These decay products carry information about the decaying nuclei.Fragmentation events may result in high yields of boson particles,especially alpha particles,and may carry important information about the nuclear Bose Einstein condensate(BEC).We study‘in medium’fourαcorrelations and link them to the‘fission’of 16O in two 8Be in the ground state or 12C*(Hoyle state)+α.Using novel techniques for the correlation functions,we confirm the resonance of 16O at 15.2 MeV excitation energy,and the possibility of a lower resonance,close to 14.72 MeV.The latter resonance is the result of allαparticles having 92 keV relative kinetic energies.
