硬塑盒气调保鲜包装机的设计

文中论述一种自主开发的硬塑盒气调保鲜包装机的工作原理及结构，深入分析其主要技术性能和设计要点。     

Numerical Study of Solid Iron Carburization in a Carbon Monoxide Atmosphere

The diffusion step during the high temperature carburization of a spherical iron particle in a carbon monoxide atmosphere is mathematically modeled and numerically simulated in this work. The continuity equation is numerically solved using a forward finite-differences scheme, and a temperature range of 1,486-1,664 K is considered. An integration time during which the solid iron particle is not yet melted is assumed. The programming code was verified using experimental results previously reported by other authors. Radial carbon concentration is determined for several temperatures, and the average carbon concentration in the particle is obtained by numerical integration.     

用Ar气制备在基管的研究

比较了在碳弧法中制各布基管时．用氦（He）气氛和用氩（Ar）气氛的制各工艺条件、阴极沉积物的生长速率、布基管产率与惰性气体压强的关系。研究表明，用Ar气氛制各布基管优于传统的用He气氛制备布基管。     

Brinkman-Forchheimer方程的加罚有限元方法

Brinkman-Forchheimer方程(BF方程)是具有强非线性项并满足无散度条件的流动控制方程,其中无散度条件的精确满足对控制方程的数值求解极其重要.为了放松无散度条件的限制,本文采用了加罚方法.为了得到加罚问题解的适定性,首先,利用加罚关系将压力项消去,证明了速度所满足的具有单调性的非线性椭圆变分问题等价于对应能量泛函的极小化问题,从而得到了速度的存在唯一性.进一步,利用LBB条件证明了BF方程加罚问题压力的存在唯一性.其次,证明了BF方程加罚问题的Galerkin变分问题的解关于加罚参数收敛到BF方程的Galerkin变分问题的解.最后,给出了BF方程加罚问题Galerkin变分问题的有限维逼近问题及其解的存在唯一性,并且得出了采用协调有限元离散的误差估计.数值算例表明加罚方法是有效的.     

模拟沿海大气环境下铝合金搭接件电偶腐蚀行为研究

铝合金搭接结构材料2A12与螺栓材料ML30CrMnSiA因存在电位差,在沿海潮湿的大气环境中服役时会发生电偶腐蚀。采用自制实验装置模拟沿海大气环境,通过电化学极化曲线测试法分别测量铝合金材料和螺栓材料在0.5mm厚液膜下的边界值,运用数值仿真软件BEASY对搭接件表面偶合后的电位、电流密度分布及腐蚀速率进行模拟计算。研究结果表明,铝合金板2A12与螺栓搭接后作为偶对阳极电位正移:与螺栓直接接触的位置,阳极极化程度最高,电偶腐蚀速率最大;随与螺栓距离增大,铝合金板的电偶腐蚀速率向两侧递减。     

Parallel Solution of Linear Systems

Computational scientists generally seek more accurate results in shorter times, and to achieve this a knowledge of evolving programming paradigms and hardware is important. In particular, optimising solvers for linear systems is a major challenge in scientific computation, and numerical algorithms must be modified or new ones created to fully use the parallel architecture of new computers. Parallel space discretisation solvers for Partial Differential Equations (PDE) such as Domain Decomposition Methods (DDM) are efficient and well documented. At first glance, parallelisation seems to be inconsistent with inherently sequential time evolution, but parallelisation is not limited to space directions. In this article, we present a new and simple method for time parallelisation, based on partial fraction decomposition of the inverse of some special matrices. We discuss its application to the heat equation and some limitations, in associated numerical experiments.     

钢箔称重法测量气氛氮势再探

对钢箔称重法测量气氛氮势做了进一步研究 ,结果表明 :用 0 .0 5 mm厚的钢箔氨渗 40 min左右 ,钢箔中的氮浓度与炉气达到平衡。5 10℃渗氮时 ,氮势与氨分解率成线性关系 :Np=0 .72 8- 0 .797α。     

两类问题的最佳逼近

本文研究了矩阵方程约束下的两类最佳逼近问题。利用矩阵的奇异值分解等技术,我们导出了这两类问题的解,并说明了现实中的许多问题是本文所研究问题的特例。     

On a Stabilization Procedure for the Parabolic Stability Equations

The numerical-stability consequences of the remaining ellipticity in the Parabolic Stability Equations (PSE) are studied. The analysis of Li and Malik of the constant-coefficient Navier-Stokes equations is extended by a detailed analysis of the parabolizing steps. Dropping of the highest streamwise derivative removes the slowest decaying upstream propagating mode, whereas the fastest remains. This mode can be numerically damped, by use of an implicit discretization of the streamwise derivative and a large enough streamwise step size. Suggestions of how to make the equations well-posed by the addition of a term proportional to the truncation error of the implicit scheme are given. This term is easy to implement, does not change the order of approximation and removes the step-size restriction. An explicit formula for the critical step size is also derived, in the modified equations, which shows that the equations are completely stabilized for a properly chosen stabilization parameter.     

一种简易无人机载大气数据计算机的设计

大气数据参数的采集和处理是无人机的关键技术之一。本文针对无人机的具体特点,给出了一种基于C51单片机的简易大气数据计算机的设计方案,并着重对系统的硬件和软件设计进行了分析和研究。实验表明该系统满足无人机的使用要求。     

新鲜瘦肉的换气包装技术

采用换气包装技术包装新鲜瘦肉可以有效地延长新鲜瘦肉的货架寿命。换气包装技术主要包含真空包装和充气包装二个工艺过程。文中给出了充填气体和包装材料的选用方法。     

The Initial Equations and the Equations for Measuring the Mass and Volume Flow Rates of a Gas

A mathematical model of the flow of a gas in Laval nozzles is analyzed. The model is used to obtain equations for measuring the mass and volume flow rates of a gas.__________Translated from Izmeritel’naya Tekhnika, No. 4, pp. 44–48, April, 2005.     

气流在喷管内流动的理论分析与数值模拟

基于气体动力学原理,由数学模型得出气流一元流动的特性:流速与压力的关系、流速与断面的关系,并分析说明原因.然后根据理论用软件进行数值模拟,结果与理论相符合.     

Modified Atmosphere Packaging of Guava Fruit

Fully matured fresh guava fruits (Lucknow‐49) were precooled at 10 °C for 1 h and pretreated with 500‐ppm benomyl for 5 min. The fruits were packed in 25‐µm and 50‐µm LDPE bags with active modified atmosphere packaging of 3% O₂ + 5% CO₂, 6% O₂ + 5% CO₂ and 9% O₂ + 5% CO₂ gas concentrations and stored at 5 ± 1 °C and 10 ± 1 °C temperatures as well as non‐packaged as control. The shelf life of guava could be increased up to 42 days by packaging in 50‐µm LDPE bags with a gas concentration of 9% O₂ + 5% CO₂ and stored at 10 °C without much change in physical, biochemical and sensory characteristics. Physico‐chemical changes viz., PLW, pulp to peel ratio, firmness, TSS, total sugar, ascorbic acid and titratable acidity were observed minimum for fruits packed in 50‐µm LDPE bags at 3% O₂ + 5% CO₂ gas concentration at 5 °C storage temperature, but sensory score decreased drastically after 21 days of storage. Chilling injury was observed for the fruits packed at 5 °C storage temperature after 21 days of storage, and it was severe in 25‐µm LDPE bag at later stage. Control fruits over‐ripened with the highest weight loss (12.47%) on 6 days of storage and discarded from the storage. Copyright © 2014 John Wiley & Sons, Ltd.     

Stabilized Finite Element Approximation of the Stationary Magneto-Hydrodynamics Equations

In this work we present a stabilized finite element method for the stationary magneto-hydrodynamic equations based on a simple algebraic version of the subgrid scale variational concept. The linearization that yields a well posed linear problem is first identified, and for this linear problem the stabilization method is designed. The key point is the correct behavior of the stabilization parameters on which the formulation depends. It is shown that their expression can be obtained only on the basis of having a correct error estimate. For the stabilization parameters chosen, a stability estimate is proved in detail, as well as the convergence of the numerical solution to the continuous one. The method is then extended to nonlinear problems and its performance checked through numerical experiments.     

钢箔称重法测量气氛氮势初探

对钢箔法测量气氛氮势做了初步研究。结果表明，钢箔法可直接测气气氛的真实氮势；钢箔称重法与钢箔化学分析法测量结果无显著差别，可以认为钢箔称重法用于生产现场气氛氮势的炉前检验是可靠的。     

Weakly nonlinear stability analysis of thin viscoelastic film flowing down on the outer surface of a rotating vertical cylinder

The paper presents both of the linear and nonlinear stability theories for characterization of viscoelastic film flows down on the outer surface of a rotating infinite vertical cylinder. After showing the insufficiency of the linear model in characterizing certain flow behaviors, a generalized nonlinear kinematic model is then derived to represent the physical system. The model is solved by the long wave perturbation method in a two-step procedure. In the first step, the normal mode method is used to characterize the linear behaviors. The amplitude growth rates and the threshold conditions are characterized subsequently and summarized as the by-products of the linear solutions. In the second step, an elaborated nonlinear film flow model is solved by using the method of multiple scales to characterize flow behaviors at various states of sub-critical stability, sub-critical instability, supercritical stability, and supercritical explosion. The modeling results indicate that by increasing the rotation speed, Ω, and decreasing the radius of cylinder, R, the film flow will generally make the flow system less stable. In this study, the interaction of the rotation and the radius of cylinder are taken into account. Generally, Reynolds number is divided into three regions, which are Re<3, 3<Re<8 and 8<Re, for discussion corresponding to the pre-selected Rossby number (Ro=0.1) and viscoelastic parameter (k=0.05).     

基于DataSocket技术的大气数据网络化测控系统研究

介绍了实现网络通信的一种极为便利的工具:DataSocket技术;分析了采用DataSocket技术实现网络测控系统的架构模式.在此基础上,介绍了应用DataSocket技术实现某型号大气数据系统的网络化测控设计方案.     

氧化气氛热处理对BaTiO3热敏电阻电性能的影响

对常阻值小于标移阻值ＰＴＣＲ热敏电阻在氧化气氛中（氧分压１ｇＰＯ２＝－０．３３５７￣－０．４９１４）于６００℃、８００℃、９００℃分别处理２ｈ、４ｈ、６ｈ,对处理的热敏电阻电性能及老化特性进行了研究。结果表明,在满足产品电性能要求的前提下,氧化气氛热处理在一定程度上可以调整ＰＴＣＲ热敏电阻的常温阻值,提高产品的合格度。     

A High-Order Difference Scheme for the Generalized Cattaneo Equation

A high-order finite difference scheme for the fractional Cattaneo equation is investigated. The $L_1$ approximation is invoked for the time fractional part, and a compact difference scheme is applied to approximate the second-order space derivative. The stability and convergence rate are discussed in the maximum norm by the energy method. Numerical examples are provided to verify the effectiveness and accuracy of the proposed difference scheme.