基于红外光谱环类锻件内壁状态监测方法研究

考虑到环类锻件内壁状态对于保证工业的生产安全具有重要作用, 而基于红外光谱的测温方法可以大大提高测温精度, 因此研究基于红外光谱的环类锻件内壁状态监测方法具有重要的意义。为了实时掌握环类锻件的内壁状态, 提出一种红外光谱环类锻件内壁状态监测方法。首先利用红外光谱构建了三级FP型LCTF的测温系统, 通过获取锻件表面辐射的两个单一光谱运用红外双色测温原理实现锻件表面温度的测量。相比传统的测温方法大大提高了锻件表面的测温精度。其次在拉普拉斯导热微分方程的基础上, 运用分离变量法建立了环类锻件内壁状态监测模型;结合红外光谱测温系统测量的温度数据和锻件自身参数信息, 实现了环类锻件的内壁状态监测;最后通过仿真实验验证了所提出方法的可行性, 实现了环类锻件的内壁状态监测, 为保证环类锻件的正常运行提供了理论依据。     

格子Boltzmann模型平衡分布边界条件和多棱柱排列渗流流场的数值模拟

介绍了适用于多种流场数值模拟的无滑动格子Boltzmann平衡分布边界条件，这一边界条件是以Bounce-Back方法为基础并满足质量、动量守恒的准则.数值计算结果表明平衡分布边界条件克服了Bounce-Back方法在边界上所产生的滑动速度误差效应.利用平衡分布边界条件数值模拟了由棱柱形充填粒子构成的微尺度渗流流场中的Darcy-Forchheimer方程，通过与Lee 和Yang的数值结果比较，该预测结果是足够可靠的. 关键词： 平衡分布边界条件 渗流介质 Darcy-Forchheimer阻力     

梯形箱梁剪力滞后效应的精细化分析

引入剪滞翘曲应力自平衡条件的影响,考虑了剪切变形和剪滞效应等因素,设置了三个不同的剪滞纵向位移差函数以准确反映梯形箱梁不同宽度翼板的剪滞变化幅度,提出了一种能对工程中常用箱梁静力学特性分析的精确解法。本文以能量变分原理为基础建立了薄壁箱梁的弹性控制微分方程和自然边界条件,获得了相应广义位移的闭合解。算例中,分析了不同荷载形式、跨宽比和悬臂板长度等因素对箱梁静力学特性的影响,结果显示出引入剪滞翘曲应力自平衡条件的必要性。     

A stability condition for turbulence model： From EMMS model to EMMS-based turbulence model

The closure problem of turbulence is still a challenging issue in turbulence modeling. In this work, a stability condition is used to close turbulence. Specifically, we regard single-phase flow as a mixture of turbulent and non-turbulent fluids, separating the structure of turbulence. Subsequently, according to the picture of the turbulent eddy cascade, the energy contained in turbulent flow is decomposed into different parts and then quantified. A turbulence stability condition, similar to the principle of the energy-minimization multi-scale （EMMS） model for gas-solid systems, is formulated to close the dynamic constraint equa- tions of turbulence, allowing the inhomogeneous structural parameters of turbulence to be optimized. We name this model as the ＂EMMS-based turbulence model＂, and use it to construct the corresponding turbulent viscosity coefficient. To validate the EMMS-based turbulence model, it is used to simulate two classical benchmark problems, lid-driven cavity flow and turbulent flow with forced convection in an empty room, The numerical results show that the EMMS-hased turbulence model improves the accuracy of turbulence modeling due to it considers the principle of compromise in competition between viscosity and inertia.     

Long-time asymptotics and the radiation condition with time-periodic boundary conditions for linear evolution equations on the half-line and experiment

The asymptotic Dirichlet-to-Neumann (D-N) map is constructed for a class of scalar, constant coefficient, linear, third-order, dispersive equations with asymptotically time/periodic Dirichlet boundary data and zero initial data on the half-line, modeling a wavemaker acting upon an initially quiescent medium. The large time $t$ asymptotics for the special cases of the linear Korteweg-de Vries and linear Benjamin–Bona–Mahony (BBM) equations are obtained. The D-N map is proven to be unique if and only if the radiation condition that selects the unique wave number branch of the dispersion relation for a sinusoidal, time-dependent boundary condition holds: (i) for frequencies in a finite interval, the wave number is real and corresponds to positive group velocity, and (ii) for frequencies outside the interval, the wave number is complex with positive imaginary part. For fixed spatial location $x$, the corresponding asymptotic solution is (i) a traveling wave or (ii) a spatially decaying, time-periodic wave. The linearized BBM asymptotics are found to quantitatively agree with viscous core-annular fluid experiments.     

Self-consistency in non-extensive thermodynamics of highly excited hadronic states

The self-consistency of a thermodynamical theory for hadronic systems based on the non-extensive statistics is investigated. We show that it is possible to obtain a self-consistent theory according to the asymptotic bootstrap principle if the mass spectrum and the energy density increase q-exponentially. A direct consequence is the existence of a limiting effective temperature for the hadronic system. We show that this result is in agreement with experiments.     

An alternative scheme for calculating the unrestricted Hartree–Fock equation: Application to the boron and neon atoms

We present an alternative scheme for calculating the unrestricted Hartree–Fock (HF) equation. The scheme is based on the variational method utilizing the sophisticated basis functions that include no adjustable parameters. The validity of the present scheme is confirmed by actual calculations of the boron and neon atoms. The total energy of the present scheme is lower than that of the conventional restrictive HF equation, but higher than that of the CI method. Also, the resultant wave function satisfies the electron–nucleus cusp condition.     

Research on the properties of some planar polynomial differential equations

In this article, we use the new method of reflecting function to study the behavior of solutions of nonlinear time-vary differential equations, and give the sufficient conditions for these equations which have the reflecting function in the form of linear and fractional. We applied the obtained results to discuss the qualitative behavior of solutions of the higher degree polynomial differential systems and derive the sufficient conditions for a critical point to be a center.     

On the Neumann function and the method of images in spherical and ellipsoidal geometry

The invention of an image system for a boundary value problem adds to a significant understanding of the structure of the problem, both at the mathematical and at the physical level. In this paper, the interior and exterior Neumann functions for the Laplacian in the cases of spherical and ellipsoidal domains are represented in terms of images. Besides isolated images, the presence of the normal derivative in the Neumann condition demands an additional continuous distribution of images, which in the spherical cases, can be restricted to a one‐dimensional manifold, whereas for the ellipsoid, both a one‐dimensional and a two‐dimensional distribution of images is needed. Copyright © 2012 John Wiley & Sons, Ltd.     

Multiple solutions of a quasilinear elliptic problem involving nonlinear boundary condition on exterior domain

In this paper, we study the multiplicity of non‐negative solutions for the quasilinear p‐Laplacian equation with the nonlinear boundary condition (1) where Δ_p denotes the p‐Laplacian operator, defined by △ _pu = div( | ? u | ^{p ? 2} ? u),1 < p < N, Ω is a smooth exterior domain in . is the outward normal derivative, . The parameters p,q,r are either or . The weight functions a(x),h(x),g(x) satisfy some suitable conditions. Using the decomposition of the Nehari manifold and the variational methods, we prove that problem (1) has at least two positive solutions provided 0 < | λ | < λ₁ for some λ₁. Copyright © 2012 John Wiley & Sons, Ltd.