Determination of surface heat-transfer coefficients of steel cylinder with phase transformation during gas quenching with high pressures

In numerical simulation of quenching process, the boundary conditions of temperature field and stress field are very important, in which the boundary conditions of temperature field are very complicated. In order to simulate the thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field. The surface heat-transfer coefficient is a key parameter. The explicit finite difference method, non-linear estimate method and the experimental relation between temperature and time during quenching have been used to solve the inverse problem of heat conduction. The relationships between surface temperature and surface heat-transfer coefficient of cylinder have been given. The non-linear surface heat-transfer coefficients include the coupled effects between phase transformation and temperature. In calculation, physical properties were treated as the function of temperature and volume fraction of constituent. The results obtained have been shown that this technique can determine effectual the surface heat-transfer coefficients during gas quenching.     

Frictional anisotropy of oriented carbon nanotube surfaces

This report examines highly anisotropic tribological behavior of multi-walled nanotube films oriented in mutually orthogonal directions. The average values of coefficient of friction varied from extremely high values (=0.795) for vertically aligned nanotubes grown on rigid substrates to very low values (=0.090) for nanotubes dispersed flat on the same substrates. The results were insensitive to humidity, in contrast to graphite materials, and indicate that nanotubes could be utilized as both low and high frictional surfaces.     

一维固结理论中固结系数的试验分析

利用长安大学改装的K0固结仪,对原状土样与重塑土样进行了固结渗透试验,根据试验所得到的数据,分别对2种土体的变形与渗透特性进行了分析,并结合太沙基一维固结理论,得到了固结系数的确定方法;在此基础上,对固结系数的变化进行了非线性分析,揭示了固结系数在固结过程中的变化规律及土体结构性对它的影响,这对准确计算地基土体的固结沉降有指导作用。     

关于近于凸函数

本文研究了近于凸函数的新子族的偏差性质,积分表示;还得到最初几项系数的精确估计。     

Consideration on Effective Diffusivity of Strontium in Granite

Abstract

Diffusive behavior of strontium and certain kinds of divalent cations in Inada granite were studied by a through-diffusion method. In order to examine the effect of sorption onto overall diffusive behavior, two kinds of solutions were used: 0.1M KCl solution and deionized water. The effective diffusion coefficient (D_e ) and rock capacity factor (a) were (2.0–3.6) xl0–¹³ m²/s and less than 0.022 in 0.1M KCl solution and (0.32–1.7) x 10 ^?13m²/s and 1.5–2.4 in deionized water respectively. The D_e , and α in deionized water were much larger than those in 0.1M KCl solution. These results are well explained by taking into account the diffusion of sorbed ion or the surface diffusion. In support of this mechanism, most D_e , values of Sr reported for various rocks are found proportional to the sorptivity ( _ρR_d )-In the case that the sorptivity is low, D_e of Sr depends on porosity like that of nonsorbed iodide. The effective diffusion coefficient of Sr in rocks was well explained by taking into account pore and surface diffusion and was expressed as D_e=2.1 xl0^?10 _? ^1.3+3.5xl0″^?12 _ρR_d . The effective diffusion coefficient of divalent cations in the granite was found proportional to their diffusion coefficients in bulk solution.     

出钢顺立案模型在宝钢炼钢厂的应用

从基本概念和程序的具体实现两方面,阐述了出钢顺立案模型的功能、特点以及在生产实践中所取得的效果。     

基于目标检测的SAR图像变化检测方法

SAR图像变化检测有着广阔的应用前景,但目前的方法普遍以精确的配准为前提,使其适用范围受到限制。针对人造目标在SAR图像上的特点,提出了一种基于目标检测的SAR图像变化检测方法。通过图像中的人造目标之间相对位置关系的相似程度确定图像的变化情况,以此来降低对图像配准精度的要求。实验表明该方法在很宽的配准精度范围内都可获得较满意的结果。     

基于数据区域发现的信息抽取规则生成方法

提出一种自动检测网页中数据记录结构特点并生成Web信息抽取规则的方法,以网页DOM树为基础,自动发现和分离Web数据区域所对应的DOM子树,将其分解为数据记录子树集合,综合数据记录子树的结构特点生成抽取规则。实验结果显示,该方法具有较高的抽取准确率和查全率。     

动态核的形态分解联想算法及抗随机噪声研究

在灰度图像分解算法和动态核形态联想记忆网络的基础上,提出了一种新的联想记忆算法--动态核的形态分解联想算法.该方法显著地提高了联想记忆抗随机噪声的能力,较好地解决了灰度图像在含噪时的联想记忆和识别的问题,从而给出了一种恢复含噪灰度图像的途径,并把该方法推广到了彩色图像的处理.通过实验,验证了该方法的良好性能,取得了理想的结果.