High temperature strength and oxidation behaviour of hot-pressed silicon nitride-disilicate ceramics

Twelve different silicon nitride-disilicate ceramics have been fabricated by hot-pressing Si3N4 with the oxides of Y, Yb, Ho, Dy, Er, Sm, Ce, Lu, La, Pr, Gd, and Sc that are used as sintering additives. The high temperature strength and oxidation behaviour of the hot-pressed ceramics were investigated and correlated with the cationic radii of the oxide additives. The flexural strength at 1200°C increased, from 666 MPa for Si3N4-La2Si2O7 to 965 MPa for Si3N4-Sc2Si2O7 which is correlated with a decreasing cationic radius of the oxide additive. The weight gain during oxidation at 1400°C for 192 h in air decreased, from 0.8732 mg cm-2 for a Si3N4-Sm2Si2O7 ceramic to 0.1089 mg cm-2 for a Si3N4-Sc2Si2O7 ceramic, which is a function of the decreasing cationic radius of the oxide additive. This revised version was published online in November 2006 with corrections to the Cover Date.     

相移掩膜应用于显示技术光刻细线化的初步研究

对基于不改造应用于显示技术的曝光设备而提高光刻解像力进行研究。用半导体工艺模拟及器件模拟软件模拟分析了离焦量为0时,两种相位移掩膜和传统掩膜下4μm/2μm等间隔线的光强分布。并根据设备参数模拟分析离焦量为15、30μm时通过掩膜得到的光刻间距情况,最后实际比较测量了两种相位移掩膜在相同条件下各自曝光剂量范围和切面微观图。实验结果表明:自准直式边缘相移掩膜相比无铬相移掩膜在产能和良率方面更有优势。自准直式边缘相移掩膜更适合显示技术光刻细线化量产使用。     

PHYSIOLOGICAL ACTIVITIES OF CHUNGKOOKJANG (KOREAN TRADITIONAL SOYBEAN PASTE) PILL AS A FUNCTIONAL FOOD

Chungkookjang, Chungkookjang pill and mushroom (Lentinus edodes) had fibrinolytic activities. The mushroom had a higher level of fibrinolytic activity (15.1 unit/mg) than Chungkookjang pill (10.0 unit/mg) and Chungkookjang (0.6 unit/mg) in spite of heat treatment. Hot‐water extracts of Chungkookjang and Chungkookjang pill showed slightly higher macrophage‐stimulating activities than the positive control, lipopolysaccharide. Also, Chungkookjang pill (3.58 µg/g) had lower cyclo‐His‐Pro content than Chungkookjang (26.5 µg/g). In addition, Chungkookjang pill had less content of flavor components than Chungkookjang and, especially, the 2,5‐dimethylpyrazine content of Chungkookjang pill was less than that of Chungkookjang. When comparing with Chungkookjang, Chungkookjang pill had similar physiological activities and more palatable flavor.     

Investigation of fatigue resistance of fillet-welded tube connection details for sign support structures

Stiffened and unstiffened fillet-welded tube-to-transverse plate connection details are widely used for mast-arm and base-plate connections for highway sign structures. However, due to repetitive wind loads, cyclic fatigue stresses are induced and they are the primary source of failure in welded connections at these locations. The resistance of fatigue critical details has been an on-going research topic because of limited experimental results and the variability in existing fatigue testing results. The main objective of this study is to evaluate fatigue resistance of fillet-welded tube connection details by utilizing the advanced fatigue tool in ANSYS Workbench platform. Finite Element (FE) models development and model validation using existing test data was presented. The resulting fatigue resistance from FE analysis was expressed in terms of fatigue life, fatigue damage, and fatigue safety factor to determine the fatigue performance of fillet-welded connections. Existing fatigue test data was grouped to perform a synthetic analysis and then analysis results were provided to determine input data and fatigue limit for the fatigue module. The local stress level at fatigue critical locations was evaluated using a static FE model for different number of stiffeners and boundary conditions. The results of this investigation provides fatigue resistance of fillet-welded connection details in the form of fatigue life, fatigue damage and safety factor for various connection parameters and structural conditions.     

高速高精度加工的几种方法

目的介绍了高速加工的数控编程策略. 方法论述了高速高精度加工的几种方法, 如待加工轨迹监控法、专家系统法、曲线插补法及试切法等. 结果与结论待加工轨迹监控法和专家系统法能够动态调节机床的进给速度, 曲线插补法能够提高机床的平均进给速度, 试切法则可以为任意半径的圆弧段设定一个最高允许进给速度.     

一种基于H.263的视频多描述编码方法

网络上传输图像与视频数据流所遇到的一个重要问题是信息包在传输过程中可能发生丢失或过度延时, 从而造成解码信号的视觉质量严重下降。多描述编码旨在通过对同一个信息源编码成多个具有一定相关性的比特流, 并在多个不同的信道上传输, 以改善不可靠信道上传输的图像与视频信号质量。提出了一种基于H. 263 的视频信号多描述编码方法, 实验结果显示了所提出方法的有效性。     

An Efficient Method for Version Control of a Tree Data Structure

A new method for version controlling of a tree structure is presented. The key feature of the method is that the latest state of a tree is retained and other versions are constructed from it on request, and information on the change history of a node is maintaind in its parent node. Several algorithms for efficient manipulation of the tree have been developed, and it has been demonstrated that they correctly manipulate the tree. The performance of these algorithms has been compared with those of other tree-based methods, and found to be nearly optimal in all aspects of the comparison. © 1997 John Wiley & Sons, Ltd.