Effects of mechanical force on crystalline structure of electrospun poly(1‐butene) membranes

Fibrous poly(1‐butene) membranes were prepared from solutions using mixed solvents via electrospinning. The electrospun fibrous poly(1‐butene) membranes were stretched at elongations of 8, 16 and 24%, respectively. Scanning electron microscopy and stress–strain analysis showed that the deformation was elastic at an elongation of 8%, while plastic deformation occurred above 16%. The crystalline transformation induced by mechanical stretching was investigated using wide‐angle X‐ray diffraction. The poly(1‐butene) membrane stretched at 24% exhibited decreased diffraction intensity at 2θ = 11.8° and 18.3°, corresponding to the (200) and (213) crystalline reflections, indicating that crystalline transformation from metastable form II to either stable form I or I′ occurred due to mechanical stretching. Copyright © 2011 Society of Chemical Industry     

热作模具用Dievar钢奥氏体形成转变动力学

采用Gleeble热模拟试验测定了Dievar钢连续加热过程中奥氏体形成的动力学曲线（CHT）。然后,根据等温转变动力学与连续转变动力学间的关系计算求得奥氏体等温形成的动力学图（IHT）。并经计算机拟合求得奥氏体等温形成和转变量的方程式。     

辐照316L不锈钢的相变研究

运用穆斯堡尔效应和X射线衍射方法对辐照前后的316L不锈钢样品中的穆斯堡尔参数和相变进行了研究。实验表明316L不锈钢经能量为54MeV的碳离子辐照后,在结构和微观参数上都发生了重大变化。同时也对样品中碳的分布和相变的类型进行了探讨。     

我国中小钢铁企业的发展方向探讨

对我国中小钢铁企业的发展方向进行了探讨,提出了一条转变增长方式、实现专业化生产、技术装备大型化、节能减排的发展道路。     

图像的多尺度边缘抑噪算法的实现

本文提出了新的基于小波变换,根据多尺度信息提取去噪边缘的方法。并提出了用模糊数学形态学方法进行图像处理,最后本文展示了实验结果。     

一类含参分叉系统最简规范形系数的计算

将参数视为状态变量,在不截断的情况下,研究了非共振含参双Hop f分叉系统的最简规范形。在采用非线性恒同变换时引入了变时间尺度函数及变参数尺度函数两个变换函数,借助于计算机代数语言M athem atica,推导出最一般情况下含一个参数的非共振双Hop f分叉系统的最简规范形的前五阶系数的表达式,并根据其中的规律推导出该系统高阶最简规范形的通式。     

A versatile chemical conversion synthesis of Cu2S nanotubes and the photovoltaic activities for dye-sensitized solar cell

A versatile, low-temperature, and low-cost chemical conversion synthesis has been developed to prepare copper sulfide (Cu₂S) nanotubes. The successful chemical conversion from ZnS nanotubes to Cu₂S ones profits by the large difference in solubility between ZnS and Cu₂S. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have further successfully employed the obtained Cu₂S nanotubes as counter electrodes in dye-sensitized solar cells. The light-to-electricity conversion results show that the Cu₂S nanostructures exhibit high photovoltaic conversion efficiency due to the increased surface area and the good electrocatalytical activity of Cu₂S. The present chemical route provides a simple way to synthesize Cu₂S nanotubes with a high surface area for nanodevice applications.     

Concatenation of electrochemical grafting with chemical or electrochemical modification for preparing electrodes with specific surface functionality

Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (–O(CH₂)₃OCO₂Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (–C₆H₄NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (–C₆H₄CH₂OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal functional group modification depends on the chemical nature of the moiety attached to the surface in the electrochemical grafting step.     

钢与不锈钢的相变超塑扩散连接

通过利用真空扩散焊设备 ,成功地进行了钢与不锈钢相变超塑扩散连接 .试验结果表明 :在一定的试验范围内 ,扩散连接接头的拉伸强度值随着循环次数N的增加而增大 ,随着加热 /冷却速度的增加而降低 .相变超塑扩散连接最佳状态参数为 :t =70 0～ 92 0℃ ,N =1 0 ,p =1 0～ 2 0MPa.     

Three‐dimensional finite element implementation of the nonuniform transformation field analysis

In this paper aspects of the nonuniform transformation field analysis (NTFA) introduced by Michel and Suquet (Int. J. Solids Struct. 2003; 40 :6937–6955) are investigated for materials with three‐dimensional microtopology. A novel implementation of the NTFA into the finite element method (FEM) is described in detail, whereas the NTFA was originally used in combination with the fast Fourier transformation (FFT). In particular, the discrete equivalents of the averaging operators required for the preprocessing steps and an algorithm for the implicit time integration and linearization of the constitutive equations of the homogenized material are provided. To the authors knowledge this is the first implementation of the method for three‐dimensional problems. Further, an alternative mode identification strategy is proposed with the aim of small computational cost in combination with good efficiency. The new identification strategy is applied to three‐dimensional metal matrix composites in order to investigate its effective non‐linear behaviour. The homogenized material model is implemented into ABAQUS/STANDARD. Numerical examples at integration point level and in terms of structural problems highlight the efficiency of the method for three‐dimensional problems. Copyright © 2010 John Wiley & Sons, Ltd.