镍基单晶合金枝晶典型区域相成分最优化测算法

建立了用于测算镍基单晶高温合金枝晶典型区域相成分的最优化数学模型.根据电子探针对枝晶典型区域成分的测定结果,运用BFGS拟Newton法及CONSTR约束优化算法,可以计算枝晶各典型区域中γ和γ＇相成分.以镍基单晶合金CMSX-2和CMSX-4为对象,对优化测算结果进行了分析,证实了该方法的可行性.     

Pd基大块金属玻璃过冷液相区与键参数的关系

通过计算机对Pd基大块金属玻璃的过冷液相区宽度△Tx的表达式进行回归处理分析，得到Pd基大块金属玻璃过冷液相区△Tx与反映合金混合热变化的3个键参数(电负性差△X、原子尺寸差的百分数δ和电子浓度n)之间存在如下关系：△Tx=29．36909 3602．45898(△x)^2 9992．76758δ^2-3．95897n^2/3，相关系数为97．2％。△Tx随多元合金的电负性差和原子尺寸差的百分数的增加而增加，而随电子浓度的增加而略有降低。     

Zr基非晶合金在过冷液相区静液挤压的变形行为及结构

研究了Zr41.2Ti13.8Cu12.5Ni10Be22.5非晶合金在过冷液相区内静液挤压的变形行为以及结构变化。结果表明:非晶合金在高应变速率下产生了明显的塑性变形,直径从16 mm变为12 mm,断裂为4段,且样品断口上随机分布着充分发展与未充分发展的脉纹式切变带,由此可看出非晶合金的变形为非牛顿体变形行为;挤压后的样品约有3%的非晶相发生晶化,在非晶基体上析出10~20 nm的纳米晶粒,导致挤压后非晶合金的热稳定性降低;静液挤压高应变速率变形条件使非晶合金产生非均匀流变,是造成非晶合金断裂的主要原因。     

正多边形盒零件冲压成形凸缘变形区的应力分布计算

首先给出正多边形盒零件凸缘变形区的应力分布式 ,接着分析了凸缘变形区的应力变化规律 ,并以0Cr18Ni9板材和方盒零件为算例给出了凸缘变形区的应力分布曲线。正多边形盒零件凸缘变形区圆角部分的拉深变形是发生皱曲和破裂之源并向直边部分转移材料 ,使直边部分松弛乃至皱曲。因此 ,对于皱曲通常选择设置压边装置 (压边圈、拉深筋等 )来解决。对于破裂通常选择增大侧壁间圆角半径或多次拉深来解决。正多边形盒零件冲压成形最好采用分区 (分块 )变压边力拉深或分区 (分块 )恒压边力拉深     

自由曲面数控加工走刀方向的优化研究

走刀方向对数控加工的效率有重要影响，尤其对于多曲面拼接自由曲面不规则轮廓区域的数控加工。针对现有自由曲面数控加工过程走刀方向优化研究存在的问题，提出了基于曲面数控加工区域划分的走刀方向优化策略，建立了简化的刀具轨迹计算模型和加工时间模型，并用实例加以验证，取得了满意的效果。     

铸钢流变性能的实验研究

本文在自行研制的高熔点合金流变性能测试装置上，进行了液态及固液共存区钢的流变性能的实验研究。测试出合金在各温度下的γ─ｔ曲线，据此建立了合金在液态及固液共存区的流变性能机械模型及本构方程，分析了铸钢流变性能与凝固过程中钢的结构变化及质点间作用力的内在联系。     

溪洛渡电厂18F机组启动试运行试验研究

总结了溪洛渡右岸18F机启动试运行试验。检验了厂家的保证值,划分了18F机在全负荷范围的稳定运行区域,并找出了各运行区域振动的主要频率。试验成果有助于溪洛渡东电机组及电网的安全运行。     

基于分块分形的工业CT图像缺陷自动定位算法

针对传统的缺陷定位必须经过图像分割和缺陷提取等步骤,识别过程比较麻烦而且费时,提出了一种基于分块分形的工业CT图像缺陷自动定位算法.该方法首先对图像进行分块处理,对每个分块区域进行分形维数计算.通过分形维数频域分布直方图进行阈值处理,标记边缘块,最后通过连通区域处理标记块,进而对缺陷进行标记定位.通过对含有不同缺陷数目的固体火箭发动机模型工业CT图像处理,均可以准确地定位缺陷.实验结果表明,该方法能有效、准确地自动定位工业CT图像缺陷,且具有较强的鲁棒性.     

How the environment determines banking efficiency: a comparison of banking firms in Taiwan,Hong Kong,and Mainland China

This study uses the three‐stage data envelopment analysis (DEA) model to explore the true managerial efficiency of the banking firms in Taiwan, Hong Kong, and Mainland China. The empirical results indicate that the environmental conditions have a significant impact on banking efficiency. When the country‐specific situations are important factors in explaining efficiency difference, the common frontier estimates obtained by neglecting those factors can generate biased and overestimated inefficiency levels. With findings obtained from the slack variable analyses, the current study can provide inefficient banks with ways to reduce their input waste through the adjustment of input allocations. The findings also confirm the importance of the three‐stage DEA and its applications in determining the true managerial efficiencies of banks. Without the three‐stage DEA, the management could be misguided when making strategic decisions and conducting inappropriate resource allocation.     

Influence of groove type on welding-induced residual stress,deformation and width of sensitization region in a SUS304 steel butt welded joint

To join a medium or thick plate weldment with a full penetration, a groove is usually prepared in the space between two sections of metal. Because weld metal needs to be deposited within the groove to form the joint, it is expected that different groove type will require different heat input, which may consequently have influence on welding residual stress and deformation. Generally, different groove corresponds to different bead layout, so it can be foreseen that the groove type has a significant effect on temperature history, shape and size of heat affected zone, and region of sensitization in certain alloys such as austenitic stainless steel. The influences of groove type on residual stress, angular distortion and width of sensitization region in a SUS304 butt-welded joint were investigated by means of numerical simulation and experiment. Based on ABAQUS code, a computational approach with considering thermo-mechanical coupling behaviors, moving heat source, strain hardening and annealing effect was developed to simulate temperature profile, stress field and deformation in multi-pass joint. Welding temperature cycles, residual stress distributions and deformations in V, K and X groove joints were calculated through using the proposed computational procedure. Meanwhile, experiments were carried out to obtain residual stress distributions and angular distortions. Through comparing the numerical results and the measured data, the effectiveness and accuracy of the developed computational approach were verified. The simulation results show that groove type has a significant influence on welding residual stress distribution, angular distortion and width of sensitization region.