High yield coaxial-type laser module packages using on-line monitoring system

The laser-welded coaxial-type laser module packages using an on-line monitoring system (OLMS) is presented. The OLMS is integrated with an ultra high precision laser displacement meter (LDM) and a laser welding system that enables to quantitatively on-line process the successive postweld shift (PWS) measurements by the LDM and corrections by the laser welding during multiple welding compensations in laser-welded laser module packages. The results show that the high-yield laser module packages with high coupling efficiency of 86-97% are obtained. The fiber shifts due to the PWS could be realigned back closer to their original position after applying multiple welding compensations, and hence the coupling powers loss due to the PWS could be recovered. This OLMS study has provided a practical package guideline for fabricating reliable laser module packages with high yield and high coupling efficiency for use in low-cost lightwave transmission systems.     

The interfacial structure of plated copper alloy resistance spot welded joint

Plated copper alloys are widely used in electron industry. The plating lay caused the farther decreasing of the welding property of copper alloys, whose intrinsic weldability was poor. In this paper, the bronze and brass specimens with nickel-tin double plating layer were joined by resistance spot welding method. The microstructure and peel strength of the joints were investigated. The experiment results show that a sandwich-like structure was obtained in the faying surface after welding, and the nickel plating layer thickness had severe effect on the reliability of the joints.     

基于空芯光子晶体光纤的微小型非本征光纤法布里-珀罗干涉应变传感器

报道了一种用空芯光子晶体光纤制作的法布里-珀罗腔体,利用光纤熔接方法将该法布里-珀罗腔体和两根普通通信单模光纤熔接起来构成的微小型光纤法布里-珀罗干涉应变传感器。这种干涉传感器制作过程仅应用了切割和熔接手段,光纤材料单一,因此受温度变化的影响小。另外,该类型传感器的干涉腔长度对干涉信号强度影响不大,其干涉腔长度可至数厘米。因此,这类传感器将在大容量、准分布式传感系统中具有极大的潜在应用价值。     

U型加劲板稳定极限承载力影响因素分析

为研究U型加劲板稳定极限承载能力受初始几何缺陷、焊接残余应力以及荷载偏心距等因素的影响, 采用考虑几何与材料双重非线性的有限元模拟方法, 对各影响因素进行参数分析. 结果表明, U型加劲板的稳定极限承载能力受初始几何缺陷的影响明显, 而焊接残余应力对其影响较初始几何缺陷更为显著; 荷载偏心距对加劲板极限承载力影响明显, 极限承载力随偏心距的增加逐渐降低, 且偏向U肋一侧时的降低幅度更大.     

低活化马氏体钢热等静压焊接接头性能初步研究

研究了低活化马氏体钢(CLF-1)热等静压(HIP)焊接接头的性能,经980℃/1h/空冷+740℃/2h/空冷的性能热处理后,接头组织保持着CLF-1钢母材回火马氏体组织;常温拉伸性能与母材相当,断口为韧窝状且有第二相粒子产生,为塑性断裂且断于焊缝;常温冲击功最高为母材的26.2%。初步分析认为焊接表面制备状态、表面污染物、表面清洗状态、表面氧化膜都会影响基体原子充分扩散,导致界面扩散层不均匀,焊缝裂纹敏感性增强,冲击功低,且不稳定。     

多层非晶薄带爆炸焊接实验设计

 非晶材料的高强度及其对温度的敏感性,导致爆炸复合制备非晶块体时下限较大而上限较小,使得焊接窗口较窄。通过对非晶薄带涂铜以降低表面硬度,分析表明其不仅能降低下限,同时使高速撞击产生的热量主要集中在涂层上,减小非晶薄带的受热影响区域;再利用损伤力学的思想,在装置设计时采用增设缺陷的方法,以削弱到达焊接界面的反射拉伸波强度,提高焊接上限;降低的下限和提高的上限能使焊接窗口有效地扩大,从而使爆炸复合制备非晶块体易于实现。     

Sensitivity comparison of gas chromatography–mass spectrometry with Cold EI and standard EI

Gas chromatography–mass spectrometry (GC–MS) with Cold EI is based on interfacing GC and MS with supersonic molecular beams (SMBs) along with electron ionization of vibrationally cold sample compounds in SMB in a fly-through ion source (hence the name Cold EI). Cold EI improves all the central performance aspects of GC–MS, and in this paper, we focus on its improvement of signal-to-noise ratio (S/N) and limits of detection (LODs). We found that the harder the compound for analysis with standard EI, the greater the Cold EI gain in S/N and LOD. The lower LOD and higher S/N of Cold EI emerge from a few reasons: (a) similar ionization yield as standard EI, (b) enhanced abundance of molecular ions, (c) elimination of vacuum background noise, (d) elimination of ion source-related peak tailing and degradation, (e) ability to lower the elution temperatures via the use of high column flow rates, and (f) greater range of thermally labile and low-volatility compounds that can be analyzed. We demonstrate the superior S/N and lower LOD of Cold EI versus standard EI in a range of compounds, from the simple-to-analyze octafluoronaphthalene all the way to reserpine and an organo-metallic compound that cannot be analyzed by standard EI. These compounds include methyl stearate, cholesterol, n-C₃₂H₆₆, large polycyclic aromatic hydrocarbons, dioctyl phthalates, diundecyl phthalate, pentachlorophenol, benzidine, lambda-cyhalothrin, and methidathion. The significantly lower Cold EI LODs that can be over 1000 times better than in standard EI further result in far superior response linearity and greater measurement dynamic range.     

考虑焊接残余应力的波形钢腹板PC梁关键细节疲劳可靠度研究

焊接残余应力对波形钢腹板细节疲劳寿命的影响不可忽略,本文以头道河大桥为工程背景,基于ABAQUS有限元软件,建立波形钢腹板焊接构件数值模型,提出不同波折角度的波形钢腹板残余应力模型。采用瞬态分析方法,分析6种典型车辆作用下波折角区域焊缝细节的应力时程。在此基础上,构建考虑焊接残余应力和车辆荷载共同作用下的波形钢腹板细节疲劳极限状态方程,讨论不同波折角度和交通增长率对疲劳可靠度指标的影响规律。研究表明,翼缘板-波形钢腹板焊接构件斜边两侧的纵向残余应力呈对称分布,焊接细节转角区域圆弧外侧的纵向残余应力整体高于圆弧内侧,随着波折角度的增加,两侧焊缝附近的纵向残余应力变大;在桥梁设计基准期取100年时,30°波折角度焊缝细节疲劳可靠度是60°波折角度的1.05倍;交通量的线性增长对头道河大桥焊缝细节的疲劳可靠度影响较大,不考虑交通增长率的焊缝细节疲劳可靠度是α=5%的1.84倍。