Effects of Nb_(2)O_(5)dopant on the radiation response of barium gallo-germanate(BGG)glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy.Owing to the Nb^(5+)$Nb^(3+)interconversion ...Effects of Nb_(2)O_(5)dopant on the radiation response of barium gallo-germanate(BGG)glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy.Owing to the Nb^(5+)$Nb^(3+)interconversion in doped samples,formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after g-ray irradiation are inhibited.Thereby,Nb_(2)O_(5)dopant can enhance radiation resistance of BGG glass,and 1.0%Nb2O5 concentration is the best.展开更多
The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed w...The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects;2) upper-bound solutions;3) accurate solutions and higher convergence rates;4) insensitivity to mesh distortion;5) Jacobian?free;6) volumetric-locking-free;and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on Al-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.展开更多
Total protection of fragile goods and equipment during transport has become critically important as fast delivery systems are growing rapidly due to the rise of mass online commerce worldwide.This paper therefore stud...Total protection of fragile goods and equipment during transport has become critically important as fast delivery systems are growing rapidly due to the rise of mass online commerce worldwide.This paper therefore studies the protection of falling eggs—one of the most fragile goods—through packaging.Intensive experiments are first conducted to obtain the critical stress at which the eggshell is damaged by falling impact.Tests are first conducted of unpackaged eggs dropping onto a granite platform from various heights.Finite element method(FEM)models of unpackaged eggs are then built to simulate the behaviour of eggs and compute their stress levels.The experimental data is compared with the results of FEM simulations to determine the critical stress at which the eggshell is damaged.A series of tests and numerical simulations are then carried out for eggs wrapped in expanded polyethylene(EPE)foam.The stress distribution of both a single egg and multiple eggs in packaging are studied.An empirical formula between the drop speed(or height)and the bottom thickness of the EPE foam packaging is obtained,which can be useful in the design of packaging for the total protection of eggs that may fall during usual transport and delivery operations.The experimental and numerical results from this study show that it is viable to protect fragile goods,as long as the EPE form packaging has sufficient thickness.The proposed study and design procedure are helpful for the selection of key parameters of foam packaging to protect fragile industry products from impact.展开更多
基金supported by China National Funds for Guangdong Key Research and Development Program(Grant No.2018B090904001)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(Grant No.2017BT01X137)+2 种基金Key Laboratory of Laser Device Technology Foundation of China Ordnance Industry Group Co.(Grant No.KLLDT202010)the Key R&D Program of Guangzhou(Grant No.202007020003)the National Natural Science Foundation of China(Grant No.52002131)。
文摘Effects of Nb_(2)O_(5)dopant on the radiation response of barium gallo-germanate(BGG)glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy.Owing to the Nb^(5+)$Nb^(3+)interconversion in doped samples,formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after g-ray irradiation are inhibited.Thereby,Nb_(2)O_(5)dopant can enhance radiation resistance of BGG glass,and 1.0%Nb2O5 concentration is the best.
文摘The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects;2) upper-bound solutions;3) accurate solutions and higher convergence rates;4) insensitivity to mesh distortion;5) Jacobian?free;6) volumetric-locking-free;and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on Al-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.
基金supported by the National Natural Science Foundation of China(Grant No.51805141)the State Key Laboratory of Advanced Design andManufacturing for Vehicle Body(Grant No.31715008)the Hebei Natural Science Foundation(Grant No.E2018202243 and E2019202201).
文摘Total protection of fragile goods and equipment during transport has become critically important as fast delivery systems are growing rapidly due to the rise of mass online commerce worldwide.This paper therefore studies the protection of falling eggs—one of the most fragile goods—through packaging.Intensive experiments are first conducted to obtain the critical stress at which the eggshell is damaged by falling impact.Tests are first conducted of unpackaged eggs dropping onto a granite platform from various heights.Finite element method(FEM)models of unpackaged eggs are then built to simulate the behaviour of eggs and compute their stress levels.The experimental data is compared with the results of FEM simulations to determine the critical stress at which the eggshell is damaged.A series of tests and numerical simulations are then carried out for eggs wrapped in expanded polyethylene(EPE)foam.The stress distribution of both a single egg and multiple eggs in packaging are studied.An empirical formula between the drop speed(or height)and the bottom thickness of the EPE foam packaging is obtained,which can be useful in the design of packaging for the total protection of eggs that may fall during usual transport and delivery operations.The experimental and numerical results from this study show that it is viable to protect fragile goods,as long as the EPE form packaging has sufficient thickness.The proposed study and design procedure are helpful for the selection of key parameters of foam packaging to protect fragile industry products from impact.
