An electrochemical surface-treatment method, has been used for modifying surface condition of large diameter CVD SiC (VV core) fibers. The average tensile strength of the fibers was increased obviously from 2270.1 to ...An electrochemical surface-treatment method, has been used for modifying surface condition of large diameter CVD SiC (VV core) fibers. The average tensile strength of the fibers was increased obviously from 2270.1 to 3002.9 MPa. X-ray photoelectron spectroscopy (XPS) studies on the treated fiber surface indicate that a silicon-oxide film (primarily alpha-SiO2) has formed, accompanying the precipitation of amorphous carbon as the products of an anode oxidation reaction. In addition, the substantial increase of fiber strength through the electrochemical treatment may be described to the formation of oxide films and elimination of defects on the fiber surface.展开更多
Nonlinear Jacobi iteration and nonlinear Gauss-Seidel iteration are proposed to solve the famous Numerov finite difference scheme for nonlinear two-points boundary value problem. The concept of supersolutions and subs...Nonlinear Jacobi iteration and nonlinear Gauss-Seidel iteration are proposed to solve the famous Numerov finite difference scheme for nonlinear two-points boundary value problem. The concept of supersolutions and subsolutions for nonlinear algebraic systems are introduced. By taking such solutions as initial values, the above two iterations provide monotone sequences, which fend to the solutions of Numerov scheme at geometric convergence rates. The global existence and uniqueness of solution of Numerov scheme are discussed also. The numerical results show the advantages of these two iterations.展开更多
A model to simulate the non-Gaussian non-white-noise random errors of gears is developed with the influence of rotational speed considered. The gear transmission errors is first decomposed into harmonic and random com...A model to simulate the non-Gaussian non-white-noise random errors of gears is developed with the influence of rotational speed considered. The gear transmission errors is first decomposed into harmonic and random components based on the spectral analysis. Then, a second-order Markov process with time-variant parameters is used to simulate the non-Gaussian non-white-noise random component of gears. The second-order Markov process is used as a shaping filter. The input of the filter is a white Gaussian noise process, and the output is the random erros of gears. Furthermore, a new dynamic and stochastic simulation model for the rotational bivration of gear transmission system is proposed. The influences of the random errors on vibration acceleration are examined by use of the developed simulation system.展开更多
In the Stratonovich-Taylor and Stratonovich-Taylor-Hall discretization schemes for stochastic differential equations (SDEs), there appear two types of multiple stochastic integrals respectively. The present work is to...In the Stratonovich-Taylor and Stratonovich-Taylor-Hall discretization schemes for stochastic differential equations (SDEs), there appear two types of multiple stochastic integrals respectively. The present work is to approximate these multiple stochastic integrals by converting them into systems of simple SDEs and solving the systems by lower order numerical schemes. The reliability of this approach is clarified in theory and demonstrated in numerical examples. In consequence, the results are applied to the strong discretization of both continuous and jump SDEs.展开更多
文摘An electrochemical surface-treatment method, has been used for modifying surface condition of large diameter CVD SiC (VV core) fibers. The average tensile strength of the fibers was increased obviously from 2270.1 to 3002.9 MPa. X-ray photoelectron spectroscopy (XPS) studies on the treated fiber surface indicate that a silicon-oxide film (primarily alpha-SiO2) has formed, accompanying the precipitation of amorphous carbon as the products of an anode oxidation reaction. In addition, the substantial increase of fiber strength through the electrochemical treatment may be described to the formation of oxide films and elimination of defects on the fiber surface.
文摘Nonlinear Jacobi iteration and nonlinear Gauss-Seidel iteration are proposed to solve the famous Numerov finite difference scheme for nonlinear two-points boundary value problem. The concept of supersolutions and subsolutions for nonlinear algebraic systems are introduced. By taking such solutions as initial values, the above two iterations provide monotone sequences, which fend to the solutions of Numerov scheme at geometric convergence rates. The global existence and uniqueness of solution of Numerov scheme are discussed also. The numerical results show the advantages of these two iterations.
文摘A model to simulate the non-Gaussian non-white-noise random errors of gears is developed with the influence of rotational speed considered. The gear transmission errors is first decomposed into harmonic and random components based on the spectral analysis. Then, a second-order Markov process with time-variant parameters is used to simulate the non-Gaussian non-white-noise random component of gears. The second-order Markov process is used as a shaping filter. The input of the filter is a white Gaussian noise process, and the output is the random erros of gears. Furthermore, a new dynamic and stochastic simulation model for the rotational bivration of gear transmission system is proposed. The influences of the random errors on vibration acceleration are examined by use of the developed simulation system.
文摘In the Stratonovich-Taylor and Stratonovich-Taylor-Hall discretization schemes for stochastic differential equations (SDEs), there appear two types of multiple stochastic integrals respectively. The present work is to approximate these multiple stochastic integrals by converting them into systems of simple SDEs and solving the systems by lower order numerical schemes. The reliability of this approach is clarified in theory and demonstrated in numerical examples. In consequence, the results are applied to the strong discretization of both continuous and jump SDEs.
