楔环连接结构的非线性静力学行为研究

通过静力加载实验,并结合3维接触有限元数值计算,研究了由2个筒体和2根楔带装配组成的楔环连接结构试件的非线性静力学行为。结果表明,在轴向拉伸下,当拉力增大到一定值时,楔环连接结构的总拉力-总轴向伸长就表现出非线性关系;在轴向-横向力联合作用下,在载荷增大过程中,楔带与壳体的接触位置会发生变化,从而导致口盖孔邻近区域应力集中位置也会发生一定变化,进而引起结构上应力随载荷的非线性变化。对楔环结构的这些非线性行为的认识为结构的设计和使用提供了概念指导。     

复合材料蜂窝夹层结构计算的一般方法和进展

本文对目前蜂窝夹层结构有限元分析的方法进行旭纳；对每一种计算模型中所包含的假设作一讨论；指出其适用范围，供设计和强度计算时参考。     

A survey of inspection strategy and sensor distribution studies in discrete-part manufacturing processes

Methodologies, modeling approaches, and the interactions between various system elements involved in inspection-allocation and sensor-distribution problems, that influence operational quality decisions, are discussed. The surveyed papers fall into two broad categories: inspection-oriented quality-assurance strategies and diagnosis-oriented sensor-distribution strategies. Within each subarea, individual papers are further classified according to the system characteristics of the physical processes being investigated and the modeling characteristics of the approaches being used. As evident from nearly 100 journal articles published in the past four decades, these two problems have received considerable attention from researchers in quality engineering, management science, operations research as well as robotic vision arenas. We find that the inspection-allocation problem has been studied rather comprehensively whereas the relatively new sensor-distribution problem has plenty of opportunities for researchers. Discussions are also presented to summarize our observations based on the classifications along with some thoughts on future research.     

Effects of Ti on N distribution and diffusion in FeTiN thin films

We studied the distribution and diffusion of N atoms in FeTiN single-layer and bilayer thin films by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). We found that in as-deposited films N atoms are first absorbed by Ti atoms, the rest being dissolved into FeTi lattices. Ti not only directly absorbs N by chemical bonding, but also decreases the energy of the N atoms that are dissolved into FeTi lattices. The diffusion study of N atoms in single layer and bilayer films showed that although the presence of Ti stabilized the /spl alpha/ phase of FeTi lattices during 200/spl deg/C annealing, the diffusion length of dissolved N in FeTi (Ti/spl les/8 at.%) lattices was still comparable to the diffusion length of N in pure Fe. Thus, the addition of a small amount of Ti in /spl alpha/-Fe lattice can not completely stabilize N atoms in the film, and the induced magnetic anisotropy of the films can still be unstable, although the /spl alpha/ phase of FeTiN is stabilized by the addition of Ti. The distribution of N atoms in bilayer films can be fitted by a simple enthalpy model.     

Complete stability of cellular neural networks with time-varying delays

In this paper, the complete stability of cellular neural networks with time-varying delays is analyzed using the induction method and the contraction mapping principle. Delay-dependent and delay-independent conditions are obtained for locally stable equilibrium points to be located anywhere, which differ from the existing results on complete stability where the existence of equilibrium points in the saturation region is necessary for complete stability and locally stable equilibrium points can be in the saturation region only. In addition, some existing stability results in the literature are special cases of a new result herein. Simulation results are also discussed by use of two illustrative examples.     

The growth of γ-LiAlO2 layer with a highly-preferred orientation on (0001) sapphire

Using vapor transport equilibration (VTE) technique we succeeded in the fabrication of single-phase γ-LiAlO2 layer on (0001) sapphire substrate. X-ray diffraction indicated that the as-fabricated layer was highly textured with [100] orientation at proper VTE treatment temperature range from 1050℃ to 1100℃. The main factors affecting the quality of the γ-LiAlO2 layer were investigated by SEM and transmission spectra. These results reveal the possibility of fabricating γ-LiAlO2 (100)// sapphire (0001) composite substrate for GaN-based epitaxial film by VTE.     

07Cr12NiMoVNb耐热钢疲劳性能研究

对07Cr12NiMoVNb钢进行了常温和550℃旋转弯曲疲劳试验,结果表明,此钢不同晶粒度时疲劳断裂行为相近,室温疲劳强度与静强度关系符合奥金格经验公式,高温疲劳强度与静强度有关,但直线关系的系数不同于常温的,需重新总结。晶粒度大小影响疲劳强度,但室温表现的不明显,550℃表现为细晶钢疲劳强度高,这正好与蠕变行为相反,粗晶钢表现出较高的蠕变强度。     

国内外高级硬线钢实物质量对比

分析对比了国内外钢厂生产的高级硬线钢的化学成分、金相组织和力学性能、显微氧化物夹杂、小方坯中心碳偏析,为改善高碳钢实物质量提供依据.     

Modification of High Performances of Polymer Cement Concrete

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A dual neural network for redundancy resolution of kinematically redundant manipulators subject to joint limits and joint velocity limits

In this paper, a recurrent neural network called the dual neural network is proposed for online redundancy resolution of kinematically redundant manipulators. Physical constraints such as joint limits and joint velocity limits, together with the drift-free criterion as a secondary task, are incorporated into the problem formulation of redundancy resolution. Compared to other recurrent neural networks, the dual neural network is piecewise linear and has much simpler architecture with only one layer of neurons. The dual neural network is shown to be globally (exponentially) convergent to optimal solutions. The dual neural network is simulated to control the PA10 robot manipulator with effectiveness demonstrated.