Influence of bubble diameter and solids concentration on bubble stability: Development of a novel analytical approach

The properties and thickness of the bubbles in the froth control the flotation process. There is no work showing how to measure bubble film composition and thickness by a straightforward manner. In this work, a novel approach, a custom-designed bubble cell associated with layer interferometry（in the UV-vis region） and FT-IR spectroscopy was used to investigate the effect of solid particle type（hydrophilic vs hydrophobic）, concentration and bubble diameter on stability of a bubble blown in air. Stability was quantified by measuring bubble lifetime and hydrated film thickness. Kerosene with silicone oil as a foaming agent was used to evaluate the impact of bubble diameter（test series I）. Frother solutions（MIBC, Dowfroth 250, Hexanol and F-150） were used for the solid type concentration experiments（test series II）. In the first series of experiments, it was determined that as the diameter of a bubble increased from 10 to 25 mm, so did the hydrated film thickness from 350 to 1000 nm. In the second series, as the silica concentration increased（0 to 10%）, an increase in bubble lifetime and hydrated film thickness was resulted（130%-250%）. An impact of solid hydrophobicity was found but to a lesser degree than expected. It is possible that the small particle size（〈0.1 m） of silica was responsible for this behavior. The findings are used to interpret the effect of solids in flotation froth.     

Probabilistic analysis of random contact force between geomembrane and granular material

A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material. The contact force distribution is exponential according to the proposed method and the grain size is the most important factor that affects the distribution of contact force. The proposed method is then verified by a series of laboratory experiments using glass beads and cobbles as granular material and a very thin pressure, indicating that film is firstly used in these experiments which give a reliable method to measure the contact force at each contact point.     

铁心电抗器气隙等效导磁面积计算

以一台实际干式带气隙铁心电抗器为例,建立电抗器的三维电磁场仿真模型,给出仿真模型内的基本假设和边界条件;采用有限元分析,计算出了不同气隙下铁心电抗器的电感值和磁路中的磁感应强度矢量图,并与部分实测数据相对比,验证了仿真模型与仿真结果的正确性.然后,以铁心电抗器的电感量为主要研究对象,定量计算在不同气隙与不同铁心直径下电抗器的电感值,给出了电感值随气隙和铁心直径的变化曲线并对其拟合及定性分析.最后,结合铁心电抗器计算公式和基本假设,推算出气隙处磁通等效导磁面积扩大系数,研究气隙等效导磁面积扩大系数随气隙和铁心直径的变化关系.所得结论可以为此类电抗器的设计计算提供一定的技术支持.     

■241.3 mm井眼等井径膨胀管封堵技术研究与评价

等井径膨胀管可作为临时套管为深部复杂地层构建临时井壁,实现复杂地层无内径损失的机械封堵作业,封堵后仍保持原有井身结构,为深井安全穿越复杂地层提供一种新的技术方案。文章在介绍等井径膨胀管系统的结构设计和技术原理基础上,重点从膨胀管材优选及应力分析、膨胀螺纹结构设计和变径膨胀锥优化设计三方面对系统关键技术进行研究,通过室内性能评价和全过程井下试验,验证了系统的功能和工艺的可行性。现场应用时,井下电视影像显示：等径膨胀后管体及螺纹仍具有良好的完整性和密封性,内径达245 mm,作为临时技术套管封堵地层,满足■241.3 mm钻头安全下入及钻井服役要求,为复杂地层等井径封堵应用奠定了基础。     

大直径薄环加工专用夹具

为加工大直径薄环类工件设计了专用的U型结构夹具。该夹具可完成内孔、外圆、端面的加工，还可重复使用。     

硅藻土涂层气孔率对大口径球铁管外表面凹陷缺陷的影响

本文主要从涂层结构 ,即涂层气孔的种类、数量论述其对大口径球铁管外表面凹陷缺陷的影响。从涂料雾化液滴大小、金属型温度、喷嘴距金属型内表面距离、喷嘴移动速度、涂料中膨润土含量、金属型转速等工艺参数来控制涂层气孔率 ,保证涂层透气性 ,从而消除凹陷缺陷     

低碳Si-Mn系TRIP钢的热处理工艺对组织的影响

低碳Si-Mn系TRIP钢有着复杂的显微组织，主要由多边形铁素体（F）＋无碳贝氏体（B）＋残留奥氏体（AR）组成。本试验采用了彩色金相法，并结合X－ray衍射、SEM和TEM等手段研究了低碳Si-Mn系TRIP钢显微组织与工艺的关系，发现随着两相区退火温度的升高，最终显微组织中铁素体基体体积分数变小，并且贝氏体量增多，残留奥氏体的稳定性呈起伏式变化；在贝氏体转变区的等温温度过高或过低，均使最终显微组织中残留奥氏体体积分数减少；在贝氏体转变区等温时，所形成贝氏体表现出粒状的特征。     

退火温度对Co-Ag颗粒膜结构及巨磁电阻效应的影响

采用磁控溅射方法在室温衬底上制备了Co30Ag70(原子百分比)颗粒膜。利用X射线衍射谱(XRD)和四探针方法研究了Co30Ag70颗粒膜沉积态及真空退火后的室温结构和室温巨磁电阻效应。结果表明：沉积态颗粒膜织构较明显，巨磁电阻效应呈现各向异性；随着退火温度的升高，Co30Ag70颗粒膜的微结构发生了演变，导致Co30Ag70颗粒膜的巨磁电阻效应呈现先降后升再降的现象，在473K达到最大值，其值约为-5．7％。     

先共析铁素体对粒状贝氏体性能的影响

本文研究了低碳合金钢先共析铁素体+粒状贝氏体混合组织与单一粒状贝氏体组织的性能,先共析铁素体的存在降低钢的机械性能,尤其是显著降低冲击韧性。     

大直径无心磨金刚石砂轮制作及修整工艺研究

大直径无心磨砂轮（一般指直径D≥500mm，厚度H≥150mm）制造工艺一直是难点，具体表现在制造过程成品率低，性能难以满足要求。本文对大直径无心磨金刚石砂轮的制造工艺进行分析和讨论，提出一套完整可行制造工艺，具体包括：通过采用梯度粒度提高粗糙度，改进工艺配方提高自锐性，对实际制造过程中注意问题进行较全面分析以提高制造成品率，并对大直径无心磨金刚石砂轮热压机常用工艺热压参数热压级功率、吨位、加热板面积等进行讨论，得出合理热压工艺参数；最后，对修整工艺进行研究，大直径无心磨金刚石砂轮对修整要求精度高而且操作困难。笔者在T8365型制动鼓镗床设计全新修整工艺，实际应用证明修整工艺可操作性强，修整精度高。