Abstract Spalling, a common failure mechanism of gear systems, greatly affects the dynamics of gears operation, which is reflected in the time-varying mesh stiffness (TVMS). Current TVMS models often ...overestimate the asymmetric spalling phenomenon and may lead to inaccuracy in identifying and predicting the spalling failure. To address this problem, in this paper, a new stiffness, namely torsional stiffness, is introduced to quantify the effect of asymmetric spalling defects, and an equivalent stiffness calculation method for different asymmetric shapes is proposed. Based on this, a shape-independent TVMS model is constructed, which can realize the fast calculation of TVMS for spalling defects with different shapes at arbitrary asymmetric locations. Furthermore, a FEM-based validation method is developed by considering diverse loading states and improving the current result extraction method. Case studies are presented to illustrate the proposed model and to analyze the effects of different types of asymmetric spalling defects on gear dynamics. The FEM validation has shown that the proposed model has a good effectiveness.
This paper introduces a new idea to obtain a better order of approximation for the Baskakov operator. We conclude two new operators from orders one and two of the Baskakov type. Also, we prove some ...directed results concerning the rate of convergence of these operators. We apply the Maple software to demonstrate how the operators converge to a specific function.
A thorough, self-contained and easily accessible treatment of the theory on the polynomial best approximation of functions with respect to maximum norms. The topics include Chebychev theory, ...Weierstraß theorems, smoothness of functions, and continuation of functions.
Polyimide (PI) films filled with K sub(0.5)Na sub(0.5)NbO sub(3) (KNN50) particles at different weight 0, 5, 10, and 15 wt % had been prepared by in-situ dispersion polymerization process. The ...thermally stimulated current (TSDC) method was used to investigate the charge carrier trap levels and their distribution of the composite films. The TSDC spectra show that pure film has Formulaomitted-peaks and Formulaomitted-peak, but the composite films only have Formulaomitted-peaks and an extraordinary peak at high temperature region. The trap parameters were calculated by an approximate model, and the results indicate that charge released of the shallow traps show a nonlinear behavior. The trap energies decrease from 0.879-0.968 eV to 0.549-0.839 eV with the increase of the KNN50 content. The surface and interface between KNN50 and PI matrix was considered to the variation of the trap levels. The extraordinary peak of the composite films was correlated with the phase transition of the KNN50 particles. copy 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39828.
The phonon spectrum of cubic BaThO(3) with the perovskite structure is calculated from first principles within the density functional theory. The analysis of unstable modes in the phonon spectrum ...enables to determine the symmetry of all possible distorted phases, calculate their energies, and show that the ground-state structure of barium thorate is Pbnm. For this structure, the static and optical dielectric constants, elastic moduli, heat capacity, Raman spectra, and the energy band gap in the IDA and GW approximations are calculated. The possibility of the structural phase transitions in BaThO(3) is also discussed.
We consider the critical behavior of the O(n)-symmetric model of the ϕ4 type with an antisymmetric tensor order parameter. According to a previous study of the one-loop approximation in the quantum ...field theory renormalization group, there is an IR-attractive fixed point in the model, and IR scaling with universal indices hence applies. Using a more specific analysis based on three-loop calculations of the renormalization-group functions and Borel conformal summation, we show that the IR behavior is in fact governed by another fixed point of the renormalization-group equations and the model therefore belongs to a different universality class than the one suggested by the simplest one-loop approximation. Nevertheless, the validity of the obtained results remains a subject for discussion.
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