Investigating effects of resistance wire heating on AISI 1023 weldment characteristics during ASAW

In this article, effects of advanced submerged arc welding process parameters on weld bead geometry have been investigated. A novel water-cooled torch has been developed which allow a use of higher preheat current values for a continuous advanced submerged arc welding (ASAW) operation. Weld beads have been deposited on AISI 1023 steel plates by varying open circuit voltage, wire feed rate, welding speed, nozzle to plate distance, and preheat current as per central composite design. The relationships between welding parameters and weldment characteristics namely bead width, penetration, reinforcement, and dilution have been developed using multiple linear regression. The effects of individual process parameters and their interactions on response parameters were examined. Finally, single and multiobjective optimization of process parameters were performed using desirability approach and Jaya algorithm. The results reveal that a smaller bead width and lower dilution can be achieved with the developed torch by allowing the use of higher preheat current values.     

基于GIS的区域坡度坡长因子提取算法

为提高基于地理信息系统的区域土壤侵蚀研究、水土保持环境效应评价、流域水文分析等的应用效率,设计新的坡度坡长(LS)因子算法,利用正向-反向遍历算法取代原累积坡长算法,以获取区域尺度下的LS因子。实验结果表明,在计算精度允许的范围内,新算法使计算机运行效率有较大幅度的提高。     

Role of α2-Adrenoceptor Subtypes in Suppression of L-Type Ca2+ Current in Mouse Cardiac Myocytes

Sarcolemmal α2 adrenoceptors (α2-AR), represented by α2A, α2B and α2C isoforms, can safeguard cardiac muscle under sympathoadrenergic surge by governing Ca²⁺ handling and contractility of cardiomyocytes. Cardiomyocyte-specific targeting of α2-AR would provide cardiac muscle-delimited stress control and enhance the efficacy of cardiac malfunction treatments. However, little is known about the specific contribution of the α2-AR subtypes in modulating cardiomyocyte functions. Herein, we analyzed the expression profile of α2A, α2B and α2C subtypes in mouse ventricle and conducted electrophysiological antagonist assay evaluating the contribution of these isoforms to the suppression of L-type Ca²⁺ current (I_CaL). Patch-clamp electro-pharmacological studies revealed that the α2-agonist-induced suppression of I_CaL involves mainly the α2C, to a lesser extent the α2B, and not the α2A isoforms. RT-qPCR evaluation revealed the presence of adra2b and adra2c (α2B and α2C isoform genes, respectively), but was unable to identify the expression of adra2a (α2A isoform gene) in the mouse left ventricle. Immunoblotting confirmed the presence only of the α2B and the α2C proteins in this tissue. The identified α2-AR isoform-linked regulation of I_CaL in the mouse ventricle provides an important molecular substrate for the cardioprotective targeting.     

大直径焊管的需求与发展

分析了大中直径焊管具有广阔的市场前景，并提出大中直径焊管的成型工艺中直缝埋弧焊具有明显的优越性。目前我国应优先采用其中的ＲＢＥ、ＪＣＯＥ工艺。     

强电流直流伸展电弧等离子体CVD金刚石沉积均匀性研究

采用特殊的等离子体技术成功研制出适合于金刚石涂层工具工业化生产的中试设备-强电流直流伸展电弧等离子体CVD-500型中试设备。单腔体沉积的沉积工件数量在100支以上;对该设备的沉积均匀性进行了系统的研究,位于等离子体扩散区同一柱面不同位置沉积的金刚石形貌及质量均匀、一致,涂层厚度的不均匀度在±3．5％的范围内;同一沉积试件不同位置处的金刚石形貌及质量稍有差别,但均在许可范围之内,涂层厚度的不均匀度在±2％的范围内;等离子体的扩散区的径向6 cm～8cm,轴向距阳极7 cm-19cm的范围为该设备的有效沉积区域。     

Experimental study on welding characteristics of CO2 laser TIG hybrid welding process

Abstract

The experiments of CO₂ laser TIG paraxial hybrid welding with 4 mm thick AISI 321 stainless steel sheet have been performed. The arc images and welding characteristics have been investigated with different energy ratios between laser and arc. The experimental results indicate that the hybrid welding is similar to laser welding and has also two welding mechanisms: deep penetration welding and heat conduction welding. Because of the effect of keyhole induced by laser, the arc root can be stabilised and compressed, and the current density and the penetration depth are all increased significantly, which show the characteristics of deep penetration welding. However, when the current is increased to a critical value, the laser induced keyhole disappears and the arc expands obviously, which decreases the penetration depth, so that the welding mechanism has been changed from deep penetration welding to heat conduction welding. Furthermore, the effects of distance between laser beam and electrode, pulsed laser and hybrid manners on hybrid welding characteristics have also been studied.     

用加速量热仪研究参比燃料的低温氧化特性(Ⅱ)

基于用加速量热仪(ARC)对参比燃料与空气的混合物在低温条件下的氧化特性的实验结果,对ARC实验结果进行了热力学和化学动力学分析．根据能量平衡方程,推导出在较小的样品质量下,考虑到密闭容器中各种基本反应物质的比热容随温度变化时,热惰性因子的准确表达式,算出参比燃料在反应过程中的实际自放热率,并根据化学动力学分析求出正庚烷和异辛烷低温氧化动力学参数．对正庚烷和异辛烷的自放热率分析发现,它们都出现双峰现象,并分别在589．4K和585．7K时有最大放热率,随后在598．5K和594．8K结束自放热．     

NV10-80大束流注入机离子源电路原理分析及维修经验浅谈

本文较为详细地分析了Eaton NV10-80大束流离子流入机离子源电路工作原理，包括ARC电压，灯丝电流，气源压力调节及固体源坩埚温度控制的电路工作原理，同时，又针对常用离子源故障解决作了剖析。由于Eaton NV10-80大束流离子注入机国内半导体厂家使用较为广泛，其它型号的离子注入机也可借鉴，本文有较高的实际指导意义。     

常用软件与ARC/INFO的数据转换

应用软件系统的增多,带给了社会用户更大的选择性,同时,不同应用软件之间的数据转换的问题也随之出现。在数据采集和编辑的实际生产过程中,往往需要应用多种软件系统才能达到最终产品的要求,这就必须进行数据转换,而进行数据转换也是数据再利用的途径之一。     

弧光保护在新能源发电中的应用

大现模的新能源发电接入系统对电力系统的影响较大,新能源的诸多特性使得传统继电保护的功能受到限制.介绍了一种采用全新原理的DPR360ARC弧光保护系统,对其在新能源发电变流设备和新能源发电母线中的应用进行了阐述.弧光保护系统通过检测故障时的弧光信号和电流突变信号实现对变流设备和母线的快速保护,解决了传统保护易受谐波干扰...