Modeling of Multiscale and Multiphase Phenomena in Materials Processing

In order to demonstrate how CFD can help scientists and engineers to better understand the fundamentals of engineering processes, a number of examples are shown and discussed. The paper covers (i) special aspects of continuous casting of steel including turbulence, motion and entrapment of non-metallic inclusions, and impact of soft reduction; (ii) multiple flow phenomena and multiscale aspects during casting of large ingots including flow-induced columnar-to-equiaxed transition and 3D formation of channel segregation; (iii) multiphase magneto-hydrodynamics during electro-slag remelting; and (iv) melt flow and solidification of thin but large centrifugal castings.     

液态金属热扩散研究

铸件凝固数值计算时高温液态金属热物理参数的选取是尚未解决的问题之一。本文在前人工作的基础上,将现场浇注（浇注圆柱形试样）与DFP参数优化结合起来。提出了一种液态金属有效导温系数α的实测方法。大量的实验与数值计算证实了该方法的可能性。有效导温系数α随液态金属温度的下降而减小。通过改变试样尺寸和浇注温度,探索了诸因素对液态金属有效导温系数的影响。     

单片机在单峰定量分析中的应用

本文介绍单峰定量分析的单片机数据处理仪。仪器由单片机基本系统、前置放大器、A/D转换、键盘、LED显示器、打印机及接口电路组成。数据处理程序由数据输入,峰采集与处理,定量计算,打印输出等四个模块组成,由监控程序调度。实现(1)数据及命令的输入;(2)峰采集,滤波,起峰,峰顶,峰结束判断,峰高,峰面积计算;(3)标准直线最大偏差,相关系数计算,未知样品浓度计算。(4)报表的打印输出。该仪器已应用于汞的定量分析。     

挤压铸造Al2O2f／ZA22过程的预制块受压行为分析

采用准三维预测块模型对Ａｌ２Ｏ３短纤维预制块在挤压铸造过程中的受压力学行为进行了分析。结果表明，纤维预制块的变形主要取决于连接纤维，连接纤维比平面纤维更容易断裂，当平面纤维断裂时，整个预制块将完全破坏。     

ZA22／Al2O3f复合材料力学性能的神经网络模拟研究

采用人工神经网络的典型模邓Ｂ－Ｐ算法对ＺＡ２２／Ａｌ２Ｏ３ｆ复合材料的力学性能进行分析和预测。     

Numerical simulation of the casting process of titanium tooth crowns and bridges

The objectives of this paper were to simulate the casting process of titanium tooth crowns and bridges; to predict and control porosity defect. A casting simulation software, MAGMASOFT, was used. The geometry of the crowns with fine details of the occlusal surface were digitized by means of laser measuring technique, then converted and read in the simulation software. Both mold filling and solidification were simulated, the shrinkage porosity was predicted by a feeding criterion, and the gas pore sensitivity was studied based on the mold filling and solidification simulations. Two types of dental prostheses (a single-crown casting and a three-unit-bridge) with various sprue designs were numerically poured, and only one optimal design for each prosthesis was recommended for real casting trial. With the numerically optimized design, real titanium dental prostheses (five replicas for each) were made on a centrifugal casting machine. All the castings endured radiographic examination, and no porosity was detected in the cast prostheses. It indicates that the numerical simulation is an efficient tool for dental casting design and porosity control. © 2001 Kluwer Academic Publishers     

不同产地红心猕猴桃品质的主成分及聚类分析

为科学评价不同产地红心猕猴桃果实品质，建立红心猕猴桃品质评价体系，采用国标和农业标准方法测定11个产地果实外观品质和内在品质等16项指标，分析其品质指标的相关性，利用主成分和聚类分析法对红心猕猴桃的品质做出综合评价。结果表明，不同产地红心猕猴桃果实外观品质和内在品质均存在差异，其中微量元素差异较大，变异系数均大于20%，纵径差异最小，变异系数仅为6.66%。主成分分析表明，16项指标简化为6个主成分，累积方差贡献率为90.950%。利用相关性和主成分分析相结合，从16项品质指标中筛选出评价红心猕猴桃品质的6项核心品质指标，即纵径、糖酸比、维生素C、Co、Sr和Ba。根据聚类分析，11个产地红心猕猴桃可划分为4类，与主成分分析判定结果一致。11个产地红心猕猴桃中，奉新品质最好，其次是苍溪、周至和松桃，西峡品质最差。     

底注式浇注系统引起的局部过热对板铸件凝固过程的影响

本文通过实浇测温法,研究了底注式浇注系统所引起的局部过热对铝合金板铸件凝固时温度分布、温度梯度分布及实际模数的影响规律,提供了影响规律表达式,可供铸造工艺设计时参考。