The stability of long span steel arch structure of globe transportation center (GTC) in the Beijing Capital International Airport was studied. Different objective models such as single arch model, composite arch model...The stability of long span steel arch structure of globe transportation center (GTC) in the Beijing Capital International Airport was studied. Different objective models such as single arch model, composite arch model and global structural model were introduced to analyze the structural stability by means of the finite element technique. The eigen buckling factor of the steel arch structure was analyzed. The geometrical nonlinearity, elastic-plastic nonlinearity and initial imperfection were taken into account in the investigation of the structural buckling, and the nonlinearity reduction factors for the steel arch structure were discussed. The effects of geometrical nonlinearity and initial imperfection on the structural buckling are light while the effect of material nonlinearity is quite remarkable. For a single steel arch, the dominant buckling mode occurs in out-of-plane of arch structure. The out-of-plane buckling factor of the composite steel arch is greater than that of the single steel arch while the in-plane buckling factor of the former is somewhat less than that of the latter. Moreover, the webs near the steel arch feet have the lowest local buckling level and the local buckling is more serious than the global buckling for the global structure.展开更多
In this paper, we investigate a class of mixed initial-boundary value problems for a kind of n × n quasilinear hyperbolic systems of conservation laws on the quarter plan. We show that the structure of the pieeew...In this paper, we investigate a class of mixed initial-boundary value problems for a kind of n × n quasilinear hyperbolic systems of conservation laws on the quarter plan. We show that the structure of the pieeewise C^1 solution u = u（t, x） of the problem, which can be regarded as a perturbation of the corresponding Riemann problem, is globally similar to that of the solution u = U（x/t） of the corresponding Riemann problem. The piecewise C^1 solution u = u（t, x） to this kind of problems is globally structure-stable if and only if it contains only non-degenerate shocks and contact discontinuities, but no rarefaction waves and other weak discontinuities.展开更多
The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling inst...The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling instability is not considered in the design codes. In this paper, the effect of web opening on both lateral torsional buckling and local buckling behaviors has been investigated. A simply supported steel I-beam has been studied under uniform bending moment around the major axis. Buckling analysis has been performed using the finite element method. Linear regression analysis has been conducted for output data to formulate an equation for the critical moment including web opening effect. The results have shown a limited reduction in the lateral torsional buckling capacity and a significant reduction in the local buckling capacity.展开更多
The theory of limit analysis is presented for a three-dimensional stability problem of excavation. In frictional soil, the failure surface has the shape of logarithm helicoid, with the outline profile defined by a log...The theory of limit analysis is presented for a three-dimensional stability problem of excavation. In frictional soil, the failure surface has the shape of logarithm helicoid, with the outline profile defined by a log- spiral curve. The internal dissipation rate of energy caused by soil cohesion and gravity power of the failure soil is obtained through theoretical derivation. By solving the energy balance equation, the stability factor for the excavation is obtained. Influence of the ratio of width to height, the slope angle, and the top angle on the stability is examined. Numerical results of the proposed algorithm are presented in the form of non dimensional graph. Examples illustrate the practical use of the results.展开更多
The authors consider systems of the form where the matrix A(u) is assumed to be strictly hyperbolic and with the property that the integral curves of the eigenvector fields are straight lines. For this class of system...The authors consider systems of the form where the matrix A(u) is assumed to be strictly hyperbolic and with the property that the integral curves of the eigenvector fields are straight lines. For this class of systems one can define a natural Riemann solver, and hence a Godunov scheme, which generalize the standard Riemann solver and Godunov scheme for conservative systems. This paper shows convergence and L1 stability for this scheme when applied to data with small total variation. The main step in the proof is to estimate the increase in the total variation produced by the scheme due to quadratic coupling terms. Using Duhamel’s principle, the problem is reduced to the estimate of the product of two Green kernels, representing probability densities of discrete random walks. The total amount of coupling is then determined by the expected number of crossings between two random walks with strictly different average speeds. This provides a discrete analogue of the arguments developed in [3,9] in connection with continuous random processes.展开更多
The use of advanced carbon nanomaterials for flexible antenna sensors has attracted great attention due to their outstanding electromechanical properties. However, carbon nanomaterial based composites have yet to over...The use of advanced carbon nanomaterials for flexible antenna sensors has attracted great attention due to their outstanding electromechanical properties. However, carbon nanomaterial based composites have yet to overcome drawbacks, such as low conductivity and toughness. In this work, a flexible multi-layer graphene film(FGF) with a high conductivity of 10~6 S/m for antenna based wearable sensors is investigated. A 1.63 GHz FGF antenna sensor exhibits significantly high strain sensitivity of 9.8 for compressive bending and 9.36 for tensile bending, which is super than the copper antenna sensor(5.39 for compressive bending and 4.05 for tensile bending). Moreover, the FGF antenna sensor shows very good mechanical flexibility, reversible deformability and structure stability, and thus is well suited for applications like wearable devices and wireless strain sensing.展开更多
The authors study a 3 x 3 rate-type viscoelastic system, which is a relaxation approximation to a 2 x 2 quasi-linear hroerbolic system, including the well-known p-system. The nonlinear stability of two-mode shock wave...The authors study a 3 x 3 rate-type viscoelastic system, which is a relaxation approximation to a 2 x 2 quasi-linear hroerbolic system, including the well-known p-system. The nonlinear stability of two-mode shock waves in this relaxation approximation is proved.展开更多
The linear stability of Lagrangian elliptic equilateral triangle homographic solutions in the classical planar three body problem depends on the mass parameter β = 27（m1m2 ＋ m2m3 ＋ m3m1）/（m1 ＋ m2 ＋ m3）2∈ [0,...The linear stability of Lagrangian elliptic equilateral triangle homographic solutions in the classical planar three body problem depends on the mass parameter β = 27（m1m2 ＋ m2m3 ＋ m3m1）/（m1 ＋ m2 ＋ m3）2∈ [0,9] and the eccentricity e ∈ [0,1）.In this paper we use Maslov-type index to study the stability of these solutions and prove that the elliptic Lagrangian solutions is hyperbolic for β ＆gt; 8 with any eccentricity.展开更多
Let X={X(t),t 0} be a process with independent increments (PII)such that E=0, D X(t)E 2<∞, lim t→∞D X(t)t=1, and there exists a majoring measure G for the jump △X of X . Under these assu...Let X={X(t),t 0} be a process with independent increments (PII)such that E=0, D X(t)E 2<∞, lim t→∞D X(t)t=1, and there exists a majoring measure G for the jump △X of X . Under these assumptions, using rather a direct method, a Strassen's law of the iterated logarithm (Strassen LIL) is established. As some special cases,the Strassen LIL for homogeneous PII and for partial sum process of i.i.d.random variables are comprised.展开更多
Under the internal dissipative condition, the Cauchy problem for inhomogeneous quasilinear hyperbolic systems with small initial data admits a unique global C1 solution, which exponentially decays to zero as t →＋∞,...Under the internal dissipative condition, the Cauchy problem for inhomogeneous quasilinear hyperbolic systems with small initial data admits a unique global C1 solution, which exponentially decays to zero as t →＋∞, while if the coefficient matrix 19 of boundary conditions satisfies the boundary dissipative condition, the mixed initialboundary value problem with small initial data for quasilinear hyperbolic systems with nonlinear terms of at least second order admits a unique global C1 solution, which also exponentially decays to zero as t →＋∞. In this paper, under more general conditions, the authors investigate the combined effect of the internal dissipative condition and the boundary dissipative condition, and prove the global existence and exponential decay of the C1 solution to the mixed initial-boundary value problem for quasilinear hyperbolic systems with small initial data. This stability result is applied to a kind of models, and an example is given to show the possible exponential instability if the corresponding conditions are not satisfied.展开更多
基金Key Project of Chinese Ministry of Educa-tion (No. 104079)National Natural Sci-ence Foundation of China (No. 10572091)
文摘The stability of long span steel arch structure of globe transportation center (GTC) in the Beijing Capital International Airport was studied. Different objective models such as single arch model, composite arch model and global structural model were introduced to analyze the structural stability by means of the finite element technique. The eigen buckling factor of the steel arch structure was analyzed. The geometrical nonlinearity, elastic-plastic nonlinearity and initial imperfection were taken into account in the investigation of the structural buckling, and the nonlinearity reduction factors for the steel arch structure were discussed. The effects of geometrical nonlinearity and initial imperfection on the structural buckling are light while the effect of material nonlinearity is quite remarkable. For a single steel arch, the dominant buckling mode occurs in out-of-plane of arch structure. The out-of-plane buckling factor of the composite steel arch is greater than that of the single steel arch while the in-plane buckling factor of the former is somewhat less than that of the latter. Moreover, the webs near the steel arch feet have the lowest local buckling level and the local buckling is more serious than the global buckling for the global structure.
基金supported by the National Natural Science Foundation of China under Grant No.10671124
文摘In this paper, we investigate a class of mixed initial-boundary value problems for a kind of n × n quasilinear hyperbolic systems of conservation laws on the quarter plan. We show that the structure of the pieeewise C^1 solution u = u（t, x） of the problem, which can be regarded as a perturbation of the corresponding Riemann problem, is globally similar to that of the solution u = U（x/t） of the corresponding Riemann problem. The piecewise C^1 solution u = u（t, x） to this kind of problems is globally structure-stable if and only if it contains only non-degenerate shocks and contact discontinuities, but no rarefaction waves and other weak discontinuities.
文摘The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling instability is not considered in the design codes. In this paper, the effect of web opening on both lateral torsional buckling and local buckling behaviors has been investigated. A simply supported steel I-beam has been studied under uniform bending moment around the major axis. Buckling analysis has been performed using the finite element method. Linear regression analysis has been conducted for output data to formulate an equation for the critical moment including web opening effect. The results have shown a limited reduction in the lateral torsional buckling capacity and a significant reduction in the local buckling capacity.
基金the National Natural Science Foundation of China(Nos.41002095,41172251 and 41272317)
文摘The theory of limit analysis is presented for a three-dimensional stability problem of excavation. In frictional soil, the failure surface has the shape of logarithm helicoid, with the outline profile defined by a log- spiral curve. The internal dissipation rate of energy caused by soil cohesion and gravity power of the failure soil is obtained through theoretical derivation. By solving the energy balance equation, the stability factor for the excavation is obtained. Influence of the ratio of width to height, the slope angle, and the top angle on the stability is examined. Numerical results of the proposed algorithm are presented in the form of non dimensional graph. Examples illustrate the practical use of the results.
基金the European TMR network"Hyperbolic Systems of Conservation Laws"! ERBFMRXCT960033
文摘The authors consider systems of the form where the matrix A(u) is assumed to be strictly hyperbolic and with the property that the integral curves of the eigenvector fields are straight lines. For this class of systems one can define a natural Riemann solver, and hence a Godunov scheme, which generalize the standard Riemann solver and Godunov scheme for conservative systems. This paper shows convergence and L1 stability for this scheme when applied to data with small total variation. The main step in the proof is to estimate the increase in the total variation produced by the scheme due to quadratic coupling terms. Using Duhamel’s principle, the problem is reduced to the estimate of the product of two Green kernels, representing probability densities of discrete random walks. The total amount of coupling is then determined by the expected number of crossings between two random walks with strictly different average speeds. This provides a discrete analogue of the arguments developed in [3,9] in connection with continuous random processes.
基金supported by the National Natural Science Foundation of China(51701146)the Natural Science Foundation of Hubei Province of China(2015CFB719)the Fundamental Research Funds for the Central Universities(WUT:2017IB015)
文摘The use of advanced carbon nanomaterials for flexible antenna sensors has attracted great attention due to their outstanding electromechanical properties. However, carbon nanomaterial based composites have yet to overcome drawbacks, such as low conductivity and toughness. In this work, a flexible multi-layer graphene film(FGF) with a high conductivity of 10~6 S/m for antenna based wearable sensors is investigated. A 1.63 GHz FGF antenna sensor exhibits significantly high strain sensitivity of 9.8 for compressive bending and 9.36 for tensile bending, which is super than the copper antenna sensor(5.39 for compressive bending and 4.05 for tensile bending). Moreover, the FGF antenna sensor shows very good mechanical flexibility, reversible deformability and structure stability, and thus is well suited for applications like wearable devices and wireless strain sensing.
文摘The authors study a 3 x 3 rate-type viscoelastic system, which is a relaxation approximation to a 2 x 2 quasi-linear hroerbolic system, including the well-known p-system. The nonlinear stability of two-mode shock waves in this relaxation approximation is proved.
基金supported by National Natural Science Foundation of China (Grant No.11131004)
文摘The linear stability of Lagrangian elliptic equilateral triangle homographic solutions in the classical planar three body problem depends on the mass parameter β = 27（m1m2 ＋ m2m3 ＋ m3m1）/（m1 ＋ m2 ＋ m3）2∈ [0,9] and the eccentricity e ∈ [0,1）.In this paper we use Maslov-type index to study the stability of these solutions and prove that the elliptic Lagrangian solutions is hyperbolic for β ＆gt; 8 with any eccentricity.
文摘Let X={X(t),t 0} be a process with independent increments (PII)such that E=0, D X(t)E 2<∞, lim t→∞D X(t)t=1, and there exists a majoring measure G for the jump △X of X . Under these assumptions, using rather a direct method, a Strassen's law of the iterated logarithm (Strassen LIL) is established. As some special cases,the Strassen LIL for homogeneous PII and for partial sum process of i.i.d.random variables are comprised.
基金supported by the National Natural Science Foundation of China(Nos.11326159,11401421)the China Postdoctoral Science Foundation(No.2014M560287)the Shanxi Scholarship Council of China(No.2013-045)
文摘Under the internal dissipative condition, the Cauchy problem for inhomogeneous quasilinear hyperbolic systems with small initial data admits a unique global C1 solution, which exponentially decays to zero as t →＋∞, while if the coefficient matrix 19 of boundary conditions satisfies the boundary dissipative condition, the mixed initialboundary value problem with small initial data for quasilinear hyperbolic systems with nonlinear terms of at least second order admits a unique global C1 solution, which also exponentially decays to zero as t →＋∞. In this paper, under more general conditions, the authors investigate the combined effect of the internal dissipative condition and the boundary dissipative condition, and prove the global existence and exponential decay of the C1 solution to the mixed initial-boundary value problem for quasilinear hyperbolic systems with small initial data. This stability result is applied to a kind of models, and an example is given to show the possible exponential instability if the corresponding conditions are not satisfied.
