材料期刊网

TANDEM and GMAW Twin Wire Welding ofQ690 Steel Used in Hydraulic Support

FANG Chen-fu , MENG Xiao-hui , HU Qing-xian , WANG Feng-jiang , REN He , WANG Hai-song , GUO Yu , MAO Ming

钢铁研究学报(英文版)

Compared with using semi-automatic gas shielded arc welding, using automatic TANDEM twin wire welding and twin wire gas metal arc welding (GMAW) to weld Q690 steel, a low-alloy high-strength structural steel used in the hydraulic support in the fully-mechanized mining face, the welding speed, deposition rate, production environment and welding quality can be obviously improved. Compared with GMAW twin wire welding, a refined microstructure in the weld and heat-affected zone (HAZ), narrow HAZ and improved joint strength were achieved with TANDEM on Q690. Also, due to the push-pull pulsed way in TANDEM welding, the droplet transfer, distribution on heat flow and interaction between two arcs were completely different from those in GMAW twin wire system. The heat input of TANDEM is only about 766% of GMAW, and correspondingly, the welding speed and welding seam can be obviously improved. The complete oscillation caused by TANDEM pulsed current occurred in the welding pool, which refined the grains in the microstructure. The results show that TANDEM twin wire welding is very suitable in the welding of Q690 used in the hydraulic support.

关键词: Q690 steel , TANDEM twin wire welding , GMAW twin wire welding , performance analysis , hydraulic support

THERMODYNAMIC PROPERTIES OF ALPHA-HELIX PROTEIN - A SOLITON APPROACH - COMMENT

Physical Review E

We disagree with the deduction of the equations of motion for the Davydov soliton and of the results in the paper by Jia-Xin Xiao et al. [Phys. Rev. A 44, 8375 (1991)]. The weakness and faults of the Davydov theory are also indicated.

关键词: davydov solitons;vibron solitons;molecules;excitation;system

预测复合材料非线性有效介电系数的割线方法

周萧明 , 胡更开

复合材料学报 doi:10.3321/j.issn:1000-3851.2004.06.026

提出了预测复合材料非线性电位移和电场强度关系的一种解析方法,该方法基于各向材料的割线介电常数,将非线性问题转化成一系列线性问题来求解.该方法适用于任意各向异性复合材料和组分材料的非线性性质,而常用的Stroud和Hui的模型只适用于各向同性复合材料和组分材料的弱线性.证明了本文方法具有Ponte Castaneda提出的变分结构.计算结果表明,当基体非线性较小时,本文模型的预测与Stroud和Hui的模型一致,但当基体非线性系数增大时,本文模型能给出合理的预测结果,而Stroud和Hui的模型则会超出基体和夹杂的性能范围.

关键词: 复合材料 , 介电常数 , 非线性 , 割线方法