Solidification and liquation cracking issues in welding

Solidification cracking can occur in the fusion zone during the solidification of the weld metal. Liquation cracking, on the other hand, can occur in the partially melted zone during the solidification of the liquated material. These two types of cracking are reviewed in this article, including the factors that affect cracking and the remedies. For more information, contact Sindo Kou, University of Wisconsin, Department of Materials Science and Engineering, 1509 University Avenue, Madison, Wisconsin 53706; (608) 262-0576; fax (608) 262-8648; e-mail kou@engr.wisc.edu.     

基于漏钢预报的连铸拉速模糊控制

利用模糊控制器和神经元的优点，基于漏钢预报较成熟的热电偶方法，设计出一种基于漏钢预报的连铸拉速模糊控制系统，在保证不产生漏钢的前提下尽可能提高铸坯的拉速，从而提高钢产量。离线模拟结果了该方法的有效性。     

High density packaging technology ultra thin package & new tab package

As electronic devices become more highly integrated, the demand for small, high pin count packages has been increasing. We have developed two new types of IC packages in response to this demand. One is an ultra thin small outline package (TSOP) which has been reduced in size from the standard SOP and the other, which uses Tape Automated Bonding (TAB) technology, is a super thin, high pin count TAB in cap (T.I.C.) package. In this paper, we present these packages and their features along with the technologies used to improve package reliability and TAB. Thin packages are vulnerable to high humidity exposure, especially after heat shock.1 The following items were therefore investigated in order to improve humidity resistance: (1) The molding compound thermal stress, (2) Water absorption into the molding compound and its effect on package cracking during solder dipping, (3) Chip attach pad area and its affect on package cracking, (4) Adhesion between molding resin and chip attach pad and its affect on humidity resistance. With the improvements made as a result of these investigations, the reliability of the new thin packages is similar to that of the standard thicker plastic packages.     

EPR study of the electronic states of β′-(BEDT-TTF)(TCNQ)

β′-(BEDT-TTF)(TCNQ) is a compound of BEDT-TTF (=ET) and TCNQ molecules aligned orthogonally with each other, forming two-dimensional sheets and one-dimensional columns of 1/4-filled π band, respectively. It is known that the metal-insulator transition occurs at 330 K at ambient pressure. We have measured the electronic spin susceptibility by means of the EPR-NMR method at 50 MHz, and the angular dependence of g-factor and line width of EPR both at Q (34 GHz) and W (94 GHz) band. We successfully confirmed that the antiferromagnetic transition occurs in ET sheets and TCNQ columns, independently.     

CCK 型催化裂化进料喷嘴及其工业应用

简要介绍了CCK型催化裂化进料喷嘴的雾化机理，性能特点以及在延炼实业集团公司400kt/a重油催化裂化装置上的工业应用情况，应用结果表明：CCK喷嘴压力降低；汽液比适中，雾化效果好，运行可靠，与原使用喉管式喷嘴对相比，轻质油产率可提高2．88个百分点，焦炭和干气（含损失）产率分别降低0．67个百分点和0．42个百分点，催化剂单耗减少了0．25kg/t，同时可提高装置的处理能力和掺渣率，取得了显著的经济效益。     

Efficient weighted least-squares algorithm for the design of FIRfilters

The weighted least-squares (WLS) technique has been widely used for the design of digital FIR filters. In the conventional WLS, the filter coefficients are obtained by performing a matrix inverse operation, which needs computation of O(N³). The authors present a new WLS algorithm that introduces an extra frequency response including implicitly the weight function. In the new algorithm, the filter coefficients can be solved just by a matrix vector multiplication. It reduces the computational complexity from O(N³ ) to O(N²)     

一种用于双凸极永磁发电机的电容储能型变换器

提出了一种用于双凸极永磁发电机(DSPMG)的电容储能型变换器(CERC)。通过分析DSPMG的电磁特性和发电原理,提出了一种针对CERC的控制策略。与传统的三相全桥整流电路(FBR)对比,在相同的负载条件下,采用CERC电路的DSPMG发电系统的输出功率有明显提升。仿真和实验均证实了所提出的拓扑和控制策略的正确性。     

基于ArcEngine的管线碰撞分析算法设计与实现

地下管线作为城市的生命线,随着城市的建设变得越来越重要。庞大复杂的现状地下管线为新的管线铺设带来了困难,在管线设计阶段解决管线碰撞问题急需解决,针对这一问题,提出了管线碰撞分析算法。首先介绍了管线碰撞分析算法的研究现状,然后阐述了几何形状下管线出现碰撞的可能情况,并给出了相应的算法设计,最后基于Arc Engine开发环境进行了算法的程序实现,并进行了结果验证和实际应用。     

Enhanced thermoelectric properties in polyaniline composites with polyaniline-coated carbon nanotubes

Polyaniline (PANI)-coated multi-walled carbon nanotubes (PANI-CNTs) were firstly synthesized by in situ polymerization and then incorporated into the PANI matrix by hot pressing to fabricate bulk PANI-CNT/PANI composites. The composites showed homogeneously dispersed CNTs into the PANI matrix with a strong interface interaction. Thermoelectric measurements at room temperature showed a significant enhancement in both the electrical conductivity and Seebeck coefficient with the addition of PANI-CNTs. At the same time, relatively low thermal conductivity was also obtained. The maximum electrical conductivity and Seebeck coefficient of the composites were up to 2.8 × 10³ S/m and 21.6 μ/K, respectively, and the maximum figure of merit reached 1.0 × 10^?3 more than three orders of magnitude higher than that of neat PANI. This study proposed a novel and effective way to fabricate bulk PANI/CNT composites with enhanced thermoelectric properties.     

热卷箱在1780热轧带钢生产线的应用

在热轧带钢生产线中,热卷箱对提高带钢质量和成材率、降低能耗至关重要。介绍了承钢1780热轧带钢生产线中热卷箱的设备组成、工作方式和使用效果,针对生产中出现的工艺参数选择、液压设备和检测设备存在的故障问题,逐一找出原因,提出了相应的解决措施。