Effective data sampling strategies and boundary condition constraints of physics-informed neural networks for identifying material properties in solid mechanics

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.

环境温度和日粮锰对肉种鸡产蛋性能、蛋品质和血浆生化指标的影响

本试验旨在研究环境温度和日粮锰对肉种鸡产蛋性能、蛋品质和血浆生化指标的影响。试验采用双因素完全随机设计,包括2个环境温度(一个正常温度,21±1°C;一个高温,32±1°C)和3个不同的饲粮锰处理(在玉米-豆粕型基础日粮中添加0 mg/kg的锰、120 mg/kg的锰(来源分别为Mn SO4·H2O和蛋白锰)。因此,试验共6个处理组,每个组6个重复,每个重复4只鸡。结果表明高温降低了蛋重(P<0.0001)、产蛋率(P<0.0001)、产蛋量(P<0.0001)、采食量(P<0.0001)、饲料转化率(P<0.0001)、蛋壳强度(P<0.05)和蛋壳厚度(P<0.0001)、血浆三碘甲状腺氨酸水平(P<0.05)、碱性磷酸酶活性(P<0.04);提高了直肠温度(P<0.0001)、血浆丙二醛水平(P<0.02)、乳酸脱氢酶(P<0.002)、天冬氨酸转氨酶和肌酸激酶的活性。与不添加锰的饲粮相比,无论添加有机锰还是无机锰都增强了肉种鸡的蛋壳强度(P<0.05),降低了血浆三碘甲状腺氨酸和蛋白质羰基含量(P≤0.05)。与不添加锰的饲粮相比,饲喂添加有机锰日粮的肉种鸡的蛋壳厚度增加(P<0.01)。环境温度和饲粮锰在产蛋率、产蛋量、采食量和饲料转化率有相互作用(P<0.05)。在正常温度下,日粮无机锰或有机锰对产蛋率、产蛋量、采食量和饲料转化率不产生影响。然而,在高温情况下,饲喂有机锰日粮提高了肉种鸡产蛋率、产蛋量、采食量和饲料转化率(P<0.03)。本试验的结果表明:在32-45周龄,高温显著降低了产蛋性能、蛋壳质量,并诱导脂质过氧化反应和组织损伤。而日粮中添加有机锰或无机锰可以增加蛋壳强度和肉种鸡耐热性,并减少了蛋白质的氧化。综上,有机锰可以减轻高温对肉种鸡产蛋性能的负面影响。

Modeling biomembranes and red blood cells by coarse-grained particle methods

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.

Dynamic mechanical properties,deformation and damage mechanisms of eutectic high-entropy alloy AlCoCrFeNi_(2.1)under plate impact

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.

Shock compression and spallation damage of high-entropy alloy Al_(0.1)CoCrFeNi

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.

Optical and thermal performance analysis of aerogel glazing technology in a commercial building of Hong Kong

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.

Four α correlations in nuclear fragmentation: a game of resonances

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.

肉鸡玉米—豆粕型日粮中最佳Zn元素的添加水平研究

该试验研究了肉鸡玉米-豆粕型日粮中最佳Zn元素的添加水平。384只1日龄肉仔鸡随机分布到各试验日粮处理组，饲养期为21d。试验处理如下：在玉米-豆粕型基础日粮中（Zn含量为28．32mg／kg日粮）添加ZnSO4·7H2O形式的Zn，添加量分别为0、20、40、60、80、100、120和140mg／kg日粮。每个处理6个重复，每个重复8只鸡。