食品微生物对超高压处理的逆境响应

 超高压（High Hydrostatic Pressure,HHP）作为一种非热杀菌技术,在食品工业中有着很广泛的应用,与传统的热加工处理相比,在保持食品品质、杀菌、钝酶等方面都有其明显的优势。通过对国内外相关文献的分析,对HHP处理后处于亚致死状态食品微生物的细胞膜、遗传与结构物质、机体代谢等方面,以及大部分食品微生物在应对外界的多种刺激时而进行的普遍性调控机制的研究进行了总结,探讨了经过HHP处理后处于亚致死状态的食品微生物在逆境下存活的应激反应。     

应力各向异性下耦合三层薄膜铁磁共振

研究铁磁/铁磁/反铁磁三层薄膜中应力各向异性场对共振场的影响.得到系统存在声学和光学两种模,并且随着应力场的增强,在某些区域声学模和光学模共振场均向高值方向移动.此外发现声学模共振场对两铁磁层厚度的依赖较大,对光学模而言,随着两铁磁层厚度的改变,应力各向异性场对其共振场的影响甚微.     

黏弹性熔体充模流动诱导残余应力模拟

流动诱导残余应力是塑料制品产生应力开裂以及翘曲变形等现象的重要原因,对成型过程中流动诱导残余应力研究具有重要意义.推导了基于黏弹性eXtended Pom-Pom本构关系的能量方程,进而建立了描述黏弹性流体非等温充模流动的气-液两相模型.用同位网格有限体积法进行了求解,得到了凝固层和剪切速率分布,给出了充填结束时影响制件力学性能的流动诱导残余应力.结果表明,型腔中凝固层的厚度与注射速率有关,注射速率越大,充模时间越短,凝固层越薄.在制品表层紧邻模壁的地方,剪切速率和残余应力几乎为零;在制品次表层的位置,制件内剪切速率和流动残余应力也较高;而在远离模壁的地方,剪切速率和流动残余应力也较小.     

Uniaxial stress influence on lattice, band gap and optical properties of n-type ZnO： first-principles calculations

The lattice,the band gap and the optical properties of n-type ZnO under uniaxial stress are investigated by firstprinciples calculations.The results show that the lattice constants change linearly with stress.Band gaps are broadened linearly as the uniaxial compressive stress increases.The change of band gap for n-type ZnO comes mainly from the contribution of stress in the c-axis direction,and the reason for band gap of n-type ZnO changing with stress is also explained.The calculated results of optical properties reveal that the imaginary part of the dielectric function decreases with the increase of uniaxial compressive stress at low energy.However,when the energy is higher than 4.0 eV,the imaginary part of the dielectric function increases with the increase of stress and a blueshift appears.There are two peaks in the absorption spectrum in an energy range of 4.0-13.0 eV.The stress coefficient of the band gap of n-type ZnO is larger than that of pure ZnO,which supplies the theoretical reference value for the modulation of the band gap of doped ZnO.     

循环流化床内颗粒团流动的研究

循环流化床颗粒相流动具有多尺度效应:单颗粒运动的微尺度、颗粒团运动的介尺度和固相运动的宏尺度。颗粒相流动参数受单颗粒运动和颗粒聚团运动的制约,同时影响气相流动。基于气体分子运动论和颗粒动理学,建立相平均稠密气固两相流流动模型。介尺度模型考虑颗粒团与单颗粒之间、颗粒团与气相之间的动量和能量的传递和耗散。模拟计算颗粒容积份额、速度等参数与实测值相吻合。     

非线性伪双曲方程初边值问题整体广义解

本文证明了一类非线性伪双曲方程初边值问题整体广义解的存在唯一性．     

On the choice of the initial value of a quadratic spline in positive interpolation

Any quadratic spline with coinciding interpolating points and breakpoints can be uniquely determined by one initial condition. We examine how to choose the initial value in positive interpolation by using a norm of the spline. Monotone interpolation is also considered. The results are illuminated by numerical examples and by an application.     

A Family of Fifth-Order Runge-Kutta Pairs

The construction of a Runge-Kutta pair of order with the minimal number of stages requires the solution of a nonlinear system of order conditions in unknowns. We define a new family of pairs which includes pairs using function evaluations per integration step as well as pairs which additionally use the first function evaluation from the next step. This is achieved by making use of Kutta's simplifying assumption on the original system of the order conditions, i.e., that all the internal nodes of a method contributing to the estimation of the endpoint solution provide, at these nodes, cost-free second-order approximations to the true solution of any differential equation. In both cases the solution of the resulting system of nonlinear equations is completely classified and described in terms of five free parameters. Optimal Runge-Kutta pairs with respect to minimized truncation error coefficients, maximal phase-lag order and various stability characteristics are presented. These pairs were selected under the assumption that they are used in Local Extrapolation Mode (the propagated solution of a problem is the one provided by the fifth-order formula of the pair). Numerical results obtained by testing the new pairs over a standard set of test problems suggest a significant improvement in efficiency when using a specific pair of the new family with minimized truncation error coefficients, instead of some other existing pairs.

     

高阶Broer-Kaup(BK)方程组的新精确解

利用扩展齐次平衡法,我们得到了1+1维和2+1维高阶BK方程组新的孤子解和无穷多有理函数解,尤其是求出了初始值问题解的封闭形式.     

Size-dependent resonance and buckling behavior of nanoplates with high-order surface stress effects

This work presents a theoretical study of the resonance frequency and buckling load of nanoplates with high-order surface stress model. A classical thin plate theory based on Kirchhoff–Love assumption is implemented with surface effects. Circular and rectangular nanoplates with simply supported end conditions are exemplified. The size-dependent solutions are compared with the simplified solutions based on simple surface stress model, and also on the classical theory of elasticity. We aim to explore the scope of applicability so that the modified continuum mechanics model could serve as a refined approach in the prediction of mechanical behavior of nanoplates.