热轧钢板的织构

综述了热轧钢板织构的形成机制和形成特点,分析了化学成分、加热温度、终轧温度、轧制速度、轧后冷却速度以及润滑对热轧织构的影响规律,并描述了热轧织构对热轧钢板塑性应变比、屈服强度和韧性的影响特点,可为热轧钢板织构和性能的优化与控制提供依据。

The Displacement and Strain Field of Three-Dimensional Rheologic Model of Earthquake Preparation

Based on the three-dimensional elastic inclusion model proposed by Dobrovolskii, we developed a rheological inclusion model to study earthquake preparation processes. By using the Corresponding Principle in the theory of rheologic mechanics, we derived the analytic expressions of viscoelastic displacement U(r, t) , V(r, t) and W(r, t), normal strains epsilon(xx) (r, t), epsilon(yy) (r, t) and epsilon(zz) (r, t) and the bulk strain theta (r, t) at an arbitrary point (x, y, z) in three directions of X axis, Y axis and Z axis produced by a three-dimensional inclusion in the semi-infinite rheologic medium defined by the standard linear rheologic model. Subsequent to the spatial-temporal variation of bulk strain being computed on the ground produced by such a spherical rheologic inclusion, interesting results are obtained, suggesting that the bulk strain produced by a hard inclusion change with time according to three stages (alpha, beta, gamma) with different characteristics, similar to that of geodetic deformation observations, but different with the results of a soft inclusion. These theoretical results can be used to explain the characteristics of spatial-temporal evolution, patterns, quadrant-distribution of earthquake precursors, the changeability, spontaneity and complexity of short-term and imminent-term precursors. It offers a theoretical base to build physical models for earthquake precursors and to predict the earthquakes.

有二次涡的激波边界层干扰流动的DPNS和NS方程计算

针对具有二次涡复杂分离再附现象的激波边界层干扰流动，数值地考察了扩散抛物化Navier-Stokes (DPNS)方程组的适用情况。壁面摩阻和压力、主涡和二次涡的涡高和涡长、分离再附位置以及流线图等特性的计算表明：DPNS方程组的数值结果均与NS方程组的数值结果很好相符。

特征向量导数计算的简单动柔度法

在计算很多特征向量导数时, 以Nelson法为代表的直接法都显出效率低下, 第二作者为此发展了直接法的一个分支—动柔度法。本文虽是动柔度法的继续, 但就非重特征值情况而言, 它是一种最好的动柔度法, 因为它像Fox法一样, “ 一步求解”便可获得通解, 然而它又不存在Fox法的缺点—支配方程的系数阵为满阵, 所以说, 在计算很多非重特征值的特征向量导数时, 简单动柔度法不仅在计算步骤上比Nelson法简单, 而且在计算时间上成倍地减少。

Application of the Conjugate Gradient Optimization Algorithm of Neural Network on Laser Machining

在应用激光技术加工复杂曲面时,通常以采样点集为插值点来建立曲面函数,然后实现曲面上任意坐标点的精确定位。人工神经网络的BP算法能实现函数插值,但计算精度偏低,往往达不到插值精确要求,造成较大的加工误差。提出人工神经网络的共轭梯度最优化插值新算法,并通过实例仿真,证明了这种曲面精确定位方法的可行性,从而为激光加工的三维精确定位提供了一种良好解决方案。这种方法已经应用在实际中。

Preliminary Studies of Practicability of Laminar Plasma Surface Treatment Process

The basic remelting and cladding tests with laminar plasma technology on metals have been conducted in order to demonstrate the possibility of the technology applied in material surface modification. The experimental results show that the properties of the modified layers of the cast iron surface can be improved notably by the remelting treatment and those of the stainless steel by the cladding treatment. The related results are also verified by microscopic studies such as scanning electron microscopic (SEM) observations, energy dispersive spectra (EDS) analysis and the Vickers hardness measurements of the surface modified layers.

三组元W/O乳化液的表面张力和雾化特性

研究了W／O型乳化液的表面张力，压力雾化喷嘴的乳化液雾化特性与乳化液的组分、乳化剂的黏度以及喷油压力的关系．实验结果表明：乳化液的表面张力接近柴油，但喷雾滴径均大于柴油，而且喷嘴的启喷压力、乳化液组分和乳化剂黏度对乳化液平均滴径均有显著影响．随着启喷压力升高，喷雾滴径明显减小；若启喷压力相同，随着乳化液中水相含量增加(不高于50％)，乳化液喷雾滴径随之增加；采用高黏度、低HLB值乳化剂配制的乳化液的喷雾滴径相对较大；内相界面特性和界面上的乳化剂会对滴径分布有重要影响．

确定低渗透油藏启动压力梯度的三种方法

了确定低渗透油藏启动压力梯度的三种方法,重点介绍了低渗油藏试井分析确定启动压力梯度的方法和实际应用意义。给出了低渗油藏试井分析模型与常规中高渗油藏试井分析模型的对比。通过实例测试资料分析,指出了目前低渗油藏试井资料分析的一种常见错误。

Application of Similarity Theory to the Characterization of Non-Transferred Laminar Plasma Jet Generation

Laminar-flow non-transferred DC plasma jets were generated by a torch with an inter-electrode insert by which the arc column was limited to a length of about 20 mm. Current–voltage characteristics, thermal efficiency and jet length, a parameter which changes greatly with the generating parameters in contrast with the almost unchangeable jet length of the turbulent plasma, were investigated systematically, by using the similarity theory combined with the corresponding experimental examination. Formulae in non-dimensional forms were derived for predicting the characteristics of the laminar plasma jet generation, within the parameter ranges where no transfer to turbulent flow occurs. Mean arc temperature in the torch channel and mean jet-flow temperature at the torch exit were obtained, and the results indicate that the thermal conductivity feature of the working gas seems to be an important factor affecting thermal efficiency of laminar plasma generation.

Numerical Simulation of Nox Formation in Coal Combustion with Inlet Natural Gas Burning

A full two-fluid model of reacting gas-particle flows and coal combustion is used to simulate coal combustion with and without inlet natural gas added in the inlet. The simulation results for the case without natural gas burning is in fair agreement with the experimental results reported in references. The simulation results of different natural gas adding positions indicate that the natural gas burning can form lean oxygen combustion enviroment at the combustor inlet region and the NOz concentration is reduced. The same result can be obtained from chemical equilibrium analysis.

Twinning and Stacking Fault Formation during Tensile Deformation of Nanocrystalline Ni

Deformation twins and stacking faults have been observed in nanocrystal line Ni, for the first time under uniaxial tensile test conditions. These partial dislocation mediated deformation mechanisms are enhanced at cryogenic test temperatures. Our observations highlight the effects of deformation conditions, temperature in particular, on deformation mechanisms in nanograins.

Dynamic behavior of a cylindrical crack in a functionally graded interlayer under torsional loading

In this paper the problem of a cylindrical crack located in a functionally graded material (FGM) interlayer between two coaxial elastic dissimilar homogeneous cylinders and subjected to a torsional impact loading is considered. The shear modulus and the mass density of the FGM interlayer are assumed to vary continuously between those of the two coaxial cylinders. This mixed boundary value problem is first reduced to a singular integral equation with a Cauchy type kernel in the Laplace domain by applying Laplace and Fourier integral transforms. The singular integral equation is then solved numerically and the dynamic stress intensity factor (DSIF) is also obtained by a numerical Laplace inversion technique. The DSIF is found to rise rapidly to a peak and then reduce and tend to the static value almost without oscillation. The influences of the crack location, the FGM interlayer thickness and the relative magnitudes of the adjoining material properties are examined. It is found among others that, by increasing the FGM gradient, the DSIF can be greatly reduced.

Identification of Nonlinear Systems Through Time-Frequency Filtering Technique

In the previous paper, a class of nonlinear system is mapped to a so-called skeleton linear model (SLM) based on the joint time-frequency analysis method. Behavior of the nonlinear system may be indicated quantitatively by the variance of the coefficients of SLM versus its response. Using this model we propose an identification method for nonlinear systems based on nonstationary vibration data in this paper. The key technique in the identification procedure is a time-frequency filtering method by which solution of the SLM is extracted from the response data of the corresponding nonlinear system. Two time-frequency filtering methods are discussed here. One is based on the quadratic time-frequency distribution and its inverse transform, the other is based on the quadratic time-frequency distribution and the wavelet transform. Both numerical examples and an experimental application are given to illustrate the validity of the technique.

一种新型的碳纤维和碳纳米管化学镀镍工艺

碳纤维是最重要的复合材料增强体之一,而碳纳米管比碳纤维具有更好的力学性能,对他们的表面改性将会对复合材料性能有很大影响.试验实现了一种对碳纤维和碳纳米管通用的化学镀镍工艺.通过对基体较好的预处理,在基体上成功地完成了化学镀镍并且较好的控制了镀层成分.同时还探讨了施镀温度、pH值和搅拌方式等对镀层的影响,试验发现pH值控制在9～10之间,温度控制在70 ℃附近并采用氮气搅拌可以获得较满意的施镀效果.

Nonequilibrium microstructures and their evolution in a Fe-Cr-W-Ni-C laser clad coating

The laser-solidified microstructural and compositional characterization and phase evolution during tempering at 963 K were investigated using an analytical transmission electron microscope with energy dispersive X-ray analysis. The cladded alloy, a powder mixture of Fe, Cr, W, Ni, and C with a weight ratio of 10:5:1:1:1, was processed with a 3 kW continuous wave CO2 laser. The processing parameters were 16 mm/s beam scanning speed, 3 mm beam diameter. 2 kW laser power, and 0.3 g/s feed rate. The coating was metallurgically bonded to the substrate, with a maximum thickness of 730 mu m, a microhardness of about 860 Hv and a volumetric dilution ratio of about 6%. Microanalyses revealed that the cladded coating possessed the hypoeutectic microstructure comprising the primary dendritic gamma-austenite and interdendritic eutectic consisted of gamma-austenite and M7C3 carbide. The gamma-austenite was a non-equilibrium phase with extended solid solution of alloying elements and a great deal of defect structures, i.e. a high density of dislocations, twins, and stacking faults existed in gamma phase. During high temperature aging, in situ carbide transformation occurred of M7C3 to M23C6 and M6C. The precipitation of M23C6, MC and M2C carbides from austenite was also observed.