天铁热力风机升级改造方案设计

通过对天铁集团高炉现状、风机现状的分析,提出了对热力厂风机升级改造的规划,确定了实施方案.该方案实施后将彻底改变风机渐进式改造的现象,使新高炉的备用机组发挥更大的作用,可增加现有高炉的风压、风量,使现有高炉的产量、冶炼强度进一步提高.     

冶炼平车移动DP总线编码器的应用

介绍了在铁合金电炉控制系统的改造中应用移动DP从站的实践,对铁合金电炉控制领域的开发及维护具有一定的借鉴作用.     

强化知识管理提高企业的应变与创新能力

处于相同行业结构和机会的企业存在着很大差别.知识管理作为作管理创新的一种成果,面对知识时代更加激烈的市场竞争和经营环境的更为不确定性,知识管理在结合企业的具体发展情况下,将为企业的发展注入新的活力.     

职业教育发展的政府失灵与市场调节

职业教育的发展,主要是在市场和政府的相互调节下运行的.但完全的政府调节不利于职业教育的健康发展,完全政府调节下的职业教育会出现政府失灵现象,因而,市场的无形调节是非常重要的.市场调节主要包括人才需求、利益导向、人事制度等方面的调节.     

浅谈我国有色金属行业的技术创新发展与对策研究

在分析我国有色金属行业现状的基础上,指出随着国际贸易的不断加深,我国有色金属发展中的技术落后、设备陈旧等问题日益突出,使整个行业的发展受到严重制约.提出技术创新是促进我国有色金属行业持续发展的关键,并对现有问题的根源及解决办法进行了初步探讨.     

浅谈黄金矿山企业的绩效考核管理

绩效考核是企业管理的重要组成部分.文中通过理论与实践的结合,阐述了黄金矿山企业绩效考核管理体系的建立、实施以及绩效考核应注意的问题.     

考虑辐射影响的隔热纤维体的热导率分形模

根据纤维体内部分形结构特点,建立了计及温度影响的隔热纤维体的热导率分形模型.通过对硅酸铝纤维SEM图像的处理,得到了不同密度下硅酸铝纤维的孔隙面积和孔隙通道曲线的分形维数,并据此计算了硅酸铝纤维的热导率.实验结果验证了本文分形热导率模型的正确性.     

减轻钒铁生产中炉底烧结的试验研究

铝热法冶炼钒铁过程中,炉底被烧结,产生含钒烧结渣.烧结渣中含有大量的钒,从而造成钒的损失,降低了钒的回收率,增加了生产成本.本试验通过对炉底打结材料和冶炼布料方式的优化,大大改善了炉底烧结状况,减少了含钒烧结渣的产出量,同时烧结渣中钒的含量也大幅度降低,从而减少了钒的流失,钒的回收率提高0.5%以上.     

包钢炼铁厂企业信息系统

介绍了包钢炼铁厂企业信息系统的发展概况、组成及覆盖范围,网络的功能和软件开发过程,详细说明了各子系统的作用,对网络应用的效益做了评估.     

强化改进措施——确保质量管理体系的绩效

面对竞争日趋激烈的设计市场,企业如何立于不败之地,就要求我们的企业改进原有的管理模式.ISO9000作为国际化标准组织至今为止颁布的唯一一个质量管理性标准,一个先进的管理方法.它的应用会极大地提升管理水平和管理力度,尤其现阶段设计市场面临着严峻的考验,国际化的管理体系的建设更是尤为重要,以先进的理念促进企业发展.     

A fast method to compute the potential in the multisphere model

A series expansion is derived for the potential distribution, caused by a dipole source in a multilayered sphere with piecewise constant conductivity. When the radial coordinate of the source approaches the radial coordinate of the field point the spherical harmonics expansion converges only very slowly. It is shown how the convergence can be improved by first calculating an asymptotic approximation of the potential and using the so-called addition-subtraction method. Since the asymptotic solution is an approximation of the true solution, it gives some insight on the dependence of the potential on the conductivities. The formulas will be given in Cartesian coordinates, so that difficulties with coordinate transformations are avoided. Attention will be paid to the (fast) computation of the partial derivatives of the potential, which is useful for inverse algorithms.     

非线性界面动力学影响下颗粒增长的界面稳定性

研究了一个带有非线性温度依赖界面动力学的颗粒生长数学模型,分析颗粒界面的演化及其形态稳定性.利用渐近展开方法,获得颗粒生长的渐近解以及界面扰动的变化率.当界面动力学增加时,界面动力学过冷减小,颗粒增长速度也减小,非线性温度依赖界面动力学使得颗粒界面生长倾向于稳定.与忽略界面动力学的情形比较,非线性界面动力学显著减弱了球颗粒的生长速度.      

Approximate Solutions for Forchheimer Flow to a Well

An exact solution for transient Forchheimer flow to a well does not currently exist. However, this paper presents a set of approximate solutions, which can be used as a framework for verifying future numerical models that incorporate Forchheimer flow to wells. These include: a large time approximation derived using the method of matched asymptotic expansion; a Laplace transform approximation of the well-bore response, designed to work well when there is significant well-bore storage and flow is very turbulent; and a simple heuristic function for when flow is very turbulent and the well radius can be assumed infinitesimally small. All the approximations are compared to equivalent finite-difference solutions.     

Semianalytical Solution of Wave-Controlled Impact on Composite Laminates

Based on a structural model for wave-controlled impact, a modified Hertzian contact law was used to investigate the impact responses of composite laminates. The original nonlinear governing equation was transformed into two linear equations using asymptotic expansion. Closed-form solution can be derived for the first linear homogeneous equation, which is the equation of motion for single degree of freedom system with viscous damping. The second linear nonhomogeneous equation was solved numerically. The overall impact responses for wave-controlled impacts can be obtained semianalytically and agree well with the numerical solutions of nonlinear governing equations. The proposed methodology is useful for providing guidance to numerical simulation of impact on complex composite structures with contact laws fitting from experimental data.     

Three-Dimensional Elasticity Solutions of Laminated Annular Spherical Shells

An asymptotic theory is presented for the analysis of laminated annular spherical shells by the perturbation method. By means of proper nondimensionalization, asymptotic expansion, and then successive integration of the basic equations through the thickness direction, we obtain the recursive sets of governing equations for the bending analysis of annular spherical shells. The method of differential quadrature is adopted for solving the problems of various orders. Illustrative examples are given to demonstrate the performance of the present asymptotic theory.     

New Approximations for Reliability Integrals

A new asymptotic expansion is applied to approximate reliability integrals. The asymptotic approximation reduces the problem of evaluating a multidimensional probability integral to solving an unconstrained minimization problem. Approximations are developed in both the transformed (independently, normally distributed) variables and the original variables. In the transformed variables, the asymptotic approximation yields a very simple formula for approximating the value of the second-order reliability method integrals. In many cases, it may be computationally expensive to transform to normal variables, and an approximation using the probability distribution for the original variables can be used. Examples are presented illustrating the accuracy of the approximations, and results are compared with some existing approximations of reliability integrals.     

Transverse Shear Stiffness of Composite Honeycomb Core with General Configuration

Based on the zeroth-order approximation of a two-scale asymptotic expansion, equivalent elastic shear coefficients of periodic structures can be evaluated via the solution of a local function τklij(y), and the homogenization process reduces to solving the local function τklij(y) by invoking local periodic boundary conditions. Then, effective transverse shear stiffness properties can be analytically predicted by reducing a local problem of a given unit cell into a 2D problem. In this paper, an analytical approach with a two-scale asymptotic homogenization technique is developed for evaluation of effective transverse shear stiffness of thin-walled honeycomb core structures with general configurations, and the governing 3D partial differential equations are solved with the assumptions of free warping constraints and constant variables through the core wall thickness. The explicit formulas for the effective transverse shear stiffness are presented for a general configuration of honeycomb core. A detailed study is given for three typical honeycomb cores consisting of sinusoidal, tubular, and hexagonal configurations, and their solutions are validated with existing equations and numerical analyses. The developed approach with certain modifications can be extended to other sandwich structures, and a summary of explicit solutions for the transverse shear stiffness of common honeycomb core configurations is provided. The lower bound solution provided in this study is a reliable approximation for engineering design and can be efficiently used for quick evaluation and optimization of general core configurations. The upper bound formula, based on the assumption of uniform shear deformation, is also given for comparison. Further, it is expected that with appropriate construction in the displacement field, the more accurate transverse stiffness can be analytically attained by taking into account the effect due to the face-sheet constraints.     

基于均匀形核的金属液滴凝固过程

研究了均匀形核的金属液滴凝固过程,应用渐近分析法求得金属液滴内晶核生长数学模型的渐近解,分析了表面张力、界面动力学参数、初始晶核尺寸和过冷度对晶核界面生长速度、晶核半径以及液滴凝固时间的影响.在一定的过冷条件下,表面张力和界面动力学参数显著减缓了晶核界面生长速度.在凝固开始的很短时间内晶核界面生长速度迅速上升,当速度上升到最大值后,随着晶核半径的增大,界面生长速度逐渐减慢,表面张力和界面动力学参数对晶核生长速度的作用也逐渐减小.过冷度越大,液滴凝固时间越短.经过在开始的瞬变凝固阶段之后,温度场从设定的初始分布迅速地调整为由过冷度、表面张力、界面动力学参数等所确定的特定温度分布.      

Frequency of Functionally Graded Plates with Three-Dimensional Asymptotic Approach

The harmonic vibration problem of functionally graded plates is studied by means of a three-dimensional asymptotic theory formulated in terms of transfer matrix. Instead of using multiple time scales expansion, the frequency is determined in a much simpler way that renders the asymptotic method to be practically validated for finding any higher-order solutions. This is illustrated by applying the refined formulation to a functionally graded rectangular plate with simply supported edges. The locally effective material properties are estimated by the Mori–Tanaka scheme. Accurate natural frequencies associated with flexural, extensional, and thickness-stretching modes are provided.     

Elastic Buckling of Multilayered Anisotropic Conical Shells

On the basis of 3D elasticity, asymptotic solutions for buckling analysis of multilayered anisotropic conical shells under axial compression are presented. By means of proper nondimensionalization, asymptotic expansion, and successive integration, the classical shell theory is derived as a first-order approximation to the 3D theory. Because the governing equations for various orders consist of partial differential equations with variable coefficients, the use of analytical techniques is restricted. The method of differential quadrature is adopted in the present study. The modifications of the buckling loads and associated buckling modes can be determined in a consistent and hierarchic manner by considering the solvability and normalization conditions for various orders. The critical loads of cross-ply conical shells with simply supported–simply supported boundary conditions are studied to demonstrate the performance of the present asymptotic theory.