This study aims at investigating the ballistic resistance and energy absorption in woven E-glass composite panels,considering different projectile nose shapes and oblique incidence angles.To that scope,three-dimension...This study aims at investigating the ballistic resistance and energy absorption in woven E-glass composite panels,considering different projectile nose shapes and oblique incidence angles.To that scope,three-dimensional finite element(FE)models of both projectiles and the laminated target are developed and numerical investigations are carried out using Abaqus Explicit solver.The composite damage model’s constitutive law encompasses nonlinear material response,material properties degradation,progressive failure,and an element deletion strategy.The cohesive surface technique is used to represent the interface between two adjacent plies in the laminate,and the traction-separation law is used to characterize the behaviors of interlaminar degradation and failure.Material responses attributable to fiber rupture,matrix cracking,and plasticity caused by micro-matrix cracking due to shear loading are taken into account with suitable damage evolution laws.The computational framework is first validated against the experimental results reported in the literature by performing ballistic impact tests on the target laminate with conical,hemispherical and blunt-ended projectile,and the numerical results showed a good comparison in terms of residual velocity.Subsequently the framework is explored in simulating more complex failure mechanisms,with particular emphasis on the influence of the impact angle of obliquity,a parameter that is not usually analyzed in the literature.In that regard,the effects of normal and oblique impact on the damage morphologies and ballistic behavior of the fabric composite target in terms of energy absorption,impact contact force,and projectile residual velocity are conducted and analyzed,comparatively.The findings showed that the ballistic impact behavior of target composite is substantially influenced by projectile nose shape and incidence angle obliquity.展开更多
An alternative strain energy method is proposed for the prediction of effective elastic properties of orthotropic materials in this paper. The method is implemented in the topology optimization procedure to design cel...An alternative strain energy method is proposed for the prediction of effective elastic properties of orthotropic materials in this paper. The method is implemented in the topology optimization procedure to design cellular solids. A comparative study is made between the strain energy method and the well-known homogenization method. Numerical results show that both methods agree well in the numerical prediction and sensitivity analysis of effective elastic tensor when homogeneous boundary conditions are properly specified. Two dimensional and three dimensional microstructures are optimized for maximum stiffness designs by combining the proposed method with the dual optimization algorithm of convex programming. Satisfactory results are obtained for a variety of design cases.展开更多
In this paper, the structure of a new chaotic bitwise dynamical system (CBDS) is described. Compared to our previous research work, it uses various random bitwise operations instead of only one. The chaotic behavior...In this paper, the structure of a new chaotic bitwise dynamical system (CBDS) is described. Compared to our previous research work, it uses various random bitwise operations instead of only one. The chaotic behavior of CBDS is mathemat- ically proven according to the Devaney's definition, and its statistical properties are verified both for uniformity and by a comprehensive, reputed and stringent battery of tests called TestU01. Furthermore, a systematic methodology developing the parallel computations is proposed for FPGA platform-based realization of this CBDS. Experiments finally validate the proposed systematic methodology.展开更多
The characterization of finite length Surface Acoustic Wave (SAW) and Bulk acoustic Wave (BAW) resonators is addressed here. The Finite Element Analysis (FEA) induces artificial wave reflections at the edges of the me...The characterization of finite length Surface Acoustic Wave (SAW) and Bulk acoustic Wave (BAW) resonators is addressed here. The Finite Element Analysis (FEA) induces artificial wave reflections at the edges of the mesh. In fact, these ones do not contribute in practice to the corresponding experimental response. The Perfectly Matched Layer (PML) method, allows to suppress the boundary reflections. In this work, we first demonstrate the basis of PML adapted to FEA formalism. Next, the results of such a method are depicted allowing a discussion on the behavior of finite acoustic resonators.展开更多
Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectropho...Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectrophotometer.The self-made four-channel measurement device was used to test the gas sensitivity of ZIF-8 material toward ethanol gas under photo-thermal synergistic excitation.The results showed that the sample was typical ZIF-8(E_(g)=4.96 eV)with a regular dodecahedron shape and the specific surface is up to 1793 m^(2)/g.The as-prepared ZIF-8 has a gas response value of 55.04 to 100 ppm ethanol at 75℃ and it shows good gas sensing selectivity and repeated stability.The excellent gas sensitivity can be attributed to the increase of free electron concentration in the ZIF-8 conduction band by photo-thermal synergistic excitation,and the large specific surface area of ZIF-8 material provides more active sites for gas-solid surface reaction.The reaction mechanism of ZIF-8 material under multi-field excitation was also discussed.展开更多
A coordinated scheduling model based on two-stage distributionally robust optimization(TSDRO)is proposed for integrated energy systems(IESs)with electricity-hydrogen hybrid energy storage.The scheduling problem of the...A coordinated scheduling model based on two-stage distributionally robust optimization(TSDRO)is proposed for integrated energy systems(IESs)with electricity-hydrogen hybrid energy storage.The scheduling problem of the IES is divided into two stages in the TSDRO-based coordinated scheduling model.The first stage addresses the day-ahead optimal scheduling problem of the IES under deterministic forecasting information,while the sec-ond stage uses a distributionally robust optimization method to determine the intraday rescheduling problem under high-order uncertainties,building upon the results of the first stage.The scheduling model also considers col-laboration among the electricity,thermal,and gas networks,focusing on economic operation and carbon emissions.The flexibility of these networks and the energy gradient utilization of hydrogen units during operation are also incor-porated into the model.To improve computational efficiency,the nonlinear formulations in the TSDRO-based coordinated scheduling model are properly linearized to obtain a Mixed-Integer Linear Programming model.The Column-Constraint Generation(C&CG)algorithm is then employed to decompose the scheduling model into a mas-ter problem and subproblems.Through the iterative solution of the master problem and subproblems,an efficient analysis of the coordinated scheduling model is achieved.Finally,the effectiveness of the proposed TSDRO-based coordinated scheduling model is verified through case studies.The simulation results demonstrate that the proposed TSDRO-based coordinated scheduling model can effectively accomplish the optimal scheduling task while consider-ing the uncertainty and flexibility of the system.Compared with traditional methods,the proposed TSDRO-based coordinated scheduling model can better balance conservativeness and robustness.展开更多
文摘This study aims at investigating the ballistic resistance and energy absorption in woven E-glass composite panels,considering different projectile nose shapes and oblique incidence angles.To that scope,three-dimensional finite element(FE)models of both projectiles and the laminated target are developed and numerical investigations are carried out using Abaqus Explicit solver.The composite damage model’s constitutive law encompasses nonlinear material response,material properties degradation,progressive failure,and an element deletion strategy.The cohesive surface technique is used to represent the interface between two adjacent plies in the laminate,and the traction-separation law is used to characterize the behaviors of interlaminar degradation and failure.Material responses attributable to fiber rupture,matrix cracking,and plasticity caused by micro-matrix cracking due to shear loading are taken into account with suitable damage evolution laws.The computational framework is first validated against the experimental results reported in the literature by performing ballistic impact tests on the target laminate with conical,hemispherical and blunt-ended projectile,and the numerical results showed a good comparison in terms of residual velocity.Subsequently the framework is explored in simulating more complex failure mechanisms,with particular emphasis on the influence of the impact angle of obliquity,a parameter that is not usually analyzed in the literature.In that regard,the effects of normal and oblique impact on the damage morphologies and ballistic behavior of the fabric composite target in terms of energy absorption,impact contact force,and projectile residual velocity are conducted and analyzed,comparatively.The findings showed that the ballistic impact behavior of target composite is substantially influenced by projectile nose shape and incidence angle obliquity.
基金The project supported by the National Natural Science Foundation of China(10372083,90405016)973 Program(2006CB601205)the Aeronautical Science Foundation(04B53080)
文摘An alternative strain energy method is proposed for the prediction of effective elastic properties of orthotropic materials in this paper. The method is implemented in the topology optimization procedure to design cellular solids. A comparative study is made between the strain energy method and the well-known homogenization method. Numerical results show that both methods agree well in the numerical prediction and sensitivity analysis of effective elastic tensor when homogeneous boundary conditions are properly specified. Two dimensional and three dimensional microstructures are optimized for maximum stiffness designs by combining the proposed method with the dual optimization algorithm of convex programming. Satisfactory results are obtained for a variety of design cases.
基金Project supported by China Postdoctoral Science Foundation(Grant No.2014M552175)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Chinese Education Ministry+1 种基金the National Natural Science Foundation of China(Grant No.61172023)the Specialized Research Foundation of Doctoral Subjects of Chinese Education Ministry(Grant No.20114420110003)
文摘In this paper, the structure of a new chaotic bitwise dynamical system (CBDS) is described. Compared to our previous research work, it uses various random bitwise operations instead of only one. The chaotic behavior of CBDS is mathemat- ically proven according to the Devaney's definition, and its statistical properties are verified both for uniformity and by a comprehensive, reputed and stringent battery of tests called TestU01. Furthermore, a systematic methodology developing the parallel computations is proposed for FPGA platform-based realization of this CBDS. Experiments finally validate the proposed systematic methodology.
基金the supports of this study by the Iran National Science Foundation (No. 98001285)Pays de Montbéliard Agglomération (France) for the support of this work。
文摘The characterization of finite length Surface Acoustic Wave (SAW) and Bulk acoustic Wave (BAW) resonators is addressed here. The Finite Element Analysis (FEA) induces artificial wave reflections at the edges of the mesh. In fact, these ones do not contribute in practice to the corresponding experimental response. The Perfectly Matched Layer (PML) method, allows to suppress the boundary reflections. In this work, we first demonstrate the basis of PML adapted to FEA formalism. Next, the results of such a method are depicted allowing a discussion on the behavior of finite acoustic resonators.
基金supported by the National Natural Science Foundation of China(No.51864028)the Yunnan Province Science and Technology Major Project for Materials Genetic Engineering of Rare and Precious Metal(No.202002AB080001)+2 种基金the Yunnan Province Funds for Distinguished Young Scientists,(No.2019FJ005)the Science Research Foundation of Yunnan Provincial Education Department(No.2022J0441)the Sichuan Science and Technology Program(No.22QYCX0097)。
文摘Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectrophotometer.The self-made four-channel measurement device was used to test the gas sensitivity of ZIF-8 material toward ethanol gas under photo-thermal synergistic excitation.The results showed that the sample was typical ZIF-8(E_(g)=4.96 eV)with a regular dodecahedron shape and the specific surface is up to 1793 m^(2)/g.The as-prepared ZIF-8 has a gas response value of 55.04 to 100 ppm ethanol at 75℃ and it shows good gas sensing selectivity and repeated stability.The excellent gas sensitivity can be attributed to the increase of free electron concentration in the ZIF-8 conduction band by photo-thermal synergistic excitation,and the large specific surface area of ZIF-8 material provides more active sites for gas-solid surface reaction.The reaction mechanism of ZIF-8 material under multi-field excitation was also discussed.
基金supported in part by the National Natural Science Foundation(51977181,52077180)Natural Science Foundation of Sichuan Province(2022NSFSC0027)+2 种基金Fok Ying-Tong Education Foundation of China(171104)14th Five-year Major Science and Technology Research Project of CRRC(2021CXZ021-2)Key research and development project of China National Railway Group Co.,Ltd(N2022J016-B).
文摘A coordinated scheduling model based on two-stage distributionally robust optimization(TSDRO)is proposed for integrated energy systems(IESs)with electricity-hydrogen hybrid energy storage.The scheduling problem of the IES is divided into two stages in the TSDRO-based coordinated scheduling model.The first stage addresses the day-ahead optimal scheduling problem of the IES under deterministic forecasting information,while the sec-ond stage uses a distributionally robust optimization method to determine the intraday rescheduling problem under high-order uncertainties,building upon the results of the first stage.The scheduling model also considers col-laboration among the electricity,thermal,and gas networks,focusing on economic operation and carbon emissions.The flexibility of these networks and the energy gradient utilization of hydrogen units during operation are also incor-porated into the model.To improve computational efficiency,the nonlinear formulations in the TSDRO-based coordinated scheduling model are properly linearized to obtain a Mixed-Integer Linear Programming model.The Column-Constraint Generation(C&CG)algorithm is then employed to decompose the scheduling model into a mas-ter problem and subproblems.Through the iterative solution of the master problem and subproblems,an efficient analysis of the coordinated scheduling model is achieved.Finally,the effectiveness of the proposed TSDRO-based coordinated scheduling model is verified through case studies.The simulation results demonstrate that the proposed TSDRO-based coordinated scheduling model can effectively accomplish the optimal scheduling task while consider-ing the uncertainty and flexibility of the system.Compared with traditional methods,the proposed TSDRO-based coordinated scheduling model can better balance conservativeness and robustness.
基金support by the China Scholarship Council(CSC).This research has additionally been funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy via the Excellence Cluster“3D Matter Made to Order”(Grant No.EXC-2082/1-390761711)which has also been supported by the Carl Zeiss Foundation through the“Carl-Zeiss-Foundation-Focus@HEiKA”,by the State of Baden-Württemberg,and by the Karlsruhe Institute of Technology(KIT).We further acknowledge support by the Helmholtz program“Materials Systems Engineering”(MSE).Muamer Kadic is grateful for support by the EIPHI Graduate School(Grant No.ANR-17-EURE-0002)Changguo Wang is grateful for support by the National Natural Science Foundation of China(Grant No.12172102).