LD抽运免调试谐振腔被动调Q的固体激光器

将免调试谐振腔应用于二极管抽运固体激光器 ,采用Cr4 + ∶YAG晶体被动调Q ,准连续二极管侧向非均匀抽运Nd∶YAG激光棒 ,传导冷却 ,KTP腔外倍频 ,具有结构紧凑、抗失调能力强的特点。获得了远场近似平顶高斯分布的激光输出 ,输出波长 0 5 3μm ,能量 5 2 2mJ pulse ,稳定性 0 5 % ,电 光转换效率 3 4 % ,脉宽～ 6ns,重复频率 10～ 4 0Hz,发散角 2 8mrad。     

Primary (granulomatous) angiitis of the central nervous system with multiple aneurysms of spinal arteries. Case report

A 55-year-old woman with primary (granulomatous) angiitis of the central nervous system in association with non-Hodgkin's lymphoma (mucosa-associated lymphoid tissue type) presented with an acute spinal subdural hemorrhage secondary to rupture of one of several fusiform inflammatory aneurysms of the spinal cord radicular arteries. The literature on hemorrhagic complications, aneurysms, and spinal cord involvement in granulomatous angiitis is reviewed. Recognition of granulomatous angiitis is important, as the condition may be responsive to immunosuppressive therapy.     

Effect of grain boundaries on isothermal solidification during transient liquid phase brazing

The influence of liquid penetration at grain boundary regions on the rate of advance of the solid-liquid interface during isothermal solidification of transient liquid phase (TLP) brazed nickel joints has been examined. The test samples used in this study were Ohno-cast nickel with a grain size of >4 mm and a fine-grained nickel with a grain size of around 40 μm. Both Ni-base materials had the same chemical composition. The rate of isothermal solidification was greater when fine-grained nickel was employed during TLP brazing using Ni-11 wt pct P filler metal at 1200 °C. Liquid penetration at grain boundaries accelerates the isothermal solidification process by increasing the effective solid-liquid interfacial area and increasing the rate of solute diffusion into the base material. An analysis of electron channeling patterns has confirmed that random high-angle boundaries have a greater influence on the rate of isothermal solidification than ordered boundaries including small-angle or twin boundaries. Formerly Visiting Scientist, Department of Metallurgy and Materials Science, University of Toronto. Formerly Postdoctoral Fellow, Department of Metallurgy and Materials Science, University of Toronto     

塔河油田S105井-S106井-S117井井区盐下奥陶系油气成藏条件分析

为了探索塔河油田石炭系盐下奥陶系储集层发育特征及成藏条件,实现新地区、新层位、新领域的突破,进一步扩大塔河油田外围盐下奥陶系含油气范围,实现增储上产,利用率先在盐下奥陶系完钻的S105井、S106井、S117井的地质录井、测井、测试等资料,结合区域地质资料,对S105井-S106井-S117井区内盐下奥陶系的区域构造特征、油源条件、储集条件、储盖组合、圈闭条件及油气藏类型进行了分析,得出的结论是盐下奥陶系恰尔巴克组-一间房组发育地层不整合-岩溶裂缝型圈闭,且油源充足,储集层发育,圈闭条件良好,易于油气成藏,指出了盐下奥陶系的勘探开发前景。     

PDC钻头对录井的影响及应对措施

钻井技术水平的不断提高和PDC钻头的广泛使用给现场录井作业带来了新问题。与传统的三牙轮钻头相比,PDC钻头突出的特点是产生的岩屑稀少、细小甚至失真,给地质录井的岩屑采集、鉴定、识别以及油气层级别的判定、解释、评价带来了一系列困难。为此,结合PDC钻头在新疆塔河、松辽盆地、鄂尔多斯等地油田的使用及录井经验,从PDC钻头条件下岩屑特征和岩性特征的分析入手,阐述使用PDC钻头对气测录井、荧光录井的影响,总结了在PDC钻头条件下搞好录井作业的应对措施,并列举了提高录井技术水平的可行途径。     

Formation and retention of local melted films in AZ91 friction stir spot welds

The formation of local melted films during friction stir spot welding of as-cast AZ91D and thixomolded AZ91 material is investigated. The average temperatures close to the tip of the rotating pin vary from 438 to 454 °C during the dwell period in friction stir spot welding. These measured temperature values are higher than the melting temperature of α-Mg + Mg₁₇Al₁₂ eutectic (437 °C). It is suggested that the temperature in the stir zone during the dwell period is determined by the relative proportions of α-Mg and (α-Mg + Mg₁₇Al₁₂) eutectic material, which are incorporated during friction stir spot welding. Based on the stir zone temperature measurements and a detailed examination of material located at the root of the pin thread it is suggested that material is moved downwards via the pin thread and into the stir zone during the dwell period in friction stir spot welding. Evidence of local melted film formation is observed in the stir zone of AZ91 spot welds. It is suggested that melted films are retained since their dissolution rate is much slower in the high temperature stir zone than it is when melted films is formed in the stir zone during Al 7075-T6 friction stir spot welding. The spontaneous melting temperature, solute diffusion rate and the thermodynamic driving force for droplet dissolution are much higher during Al 7075-T6 friction stir spot welding.     

Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds

Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness.     

Ultrasonic welding using tie-layer materials. part II: Factors affecting the lap-shear strength of ultrasonic welds

The influence of tie-layer Melt Flow Index on the lap-shear strength of ultrasonic welds in oriented polypropylene (OPP) has been evaluated. The tie-layer Melt Flow Index was varied from 0.03 dg/min to 2600 dg/min; the highest lap-shear strength properties were obtained using tie-layers that had melt flow index values between 30 and 100 dg/min. When using low Melt Flow Index tie-layers, hot spot formation and concomitant changes in fusion zone and heat-affected-zone dimensions produced stress concentrations that promoted failure in oriented polypropylene material away from the bondline region. When very high Melt Flow Index (2600 dg/min) tie-layers were used, the mode of failure during lap-shear testing was a mix of cohesive, in oriented polypropylene, and adhesive failure. The molecular weight of material at the bondline was not markedly affected by the thermal cycle produced during ultrasonic welding. Only the flash ejected when using low Melt Flow Index tie-layers exhibited any evidence of degradation; it is suggested that the ejected flash may have been degraded because of a combination of thermal, cavitation, and thermo-oxidative processes.     

空冷发电厂的热力设计与分析

本文对热力发电厂的汽轮机排汽冷却系统进行了评估。作者编制了计算机程序,并对海勒式空冷系统做了计算,结果显示了塔高、水流速与空气流量、冷却塔与散热器投资以及经济效益的关系。     

DF_4内燃机车柴油机润滑油的热重分析

通过对DF_4内燃机车柴油机润滑油的热重曲线TG和微商热重曲线DTG的分析,探讨了这种润滑油的衰变规律。