Fundamental Evaluation of Power Supply and Rectifiers for Wireless Power Transfer Using Magnetic Resonant Coupling

This paper provides a fundamental analysis of a power supply and rectifiers for wireless power transfer using magnetic resonant coupling (MRC). MRC enables efficient wireless power transfer over middle‐range transfer distances. MRC for wireless power transfer should operate at a high frequency in the industry science medical band, such as 13.56 MHz, because the size of the transfer device decreases at higher transfer frequencies. Therefore, the output frequency of the power supply on the transmitting side should be 13.56 MHz. In addition, the rectifier on the receiving side is operated at a high frequency. This paper focuses on the reflected power in the power supply and rectifiers. Thus, the parametric design method is clarified for the power supply, including a low‐pass filter to match the output, the impedance of the power supply with the characteristic impedance of the transmission line. In addition, the effects on the rectifiers of silicon carbide and gallium nitride diodes are confirmed by performing an experiment and a loss analysis.     

基于多因素耦合分析的冲击地压卸压技术研究

为有效预防ZF2803工作面的冲击地压,本文采用多因素耦合分析法研究了初次来压、见方、煤柱、断层、邻近空区支承压力、煤层厚度变化及巷道底煤等7个因素的单独影响区域及叠加效果,确定了7个危险区:中等冲击危险区4个、强冲击危险区3个,给出了相应的煤层及底板大钻孔预卸压措施,工业性应用取得了良好的防治效果。     

Photopolymerization synthesis of polyacrylic acid dispersant with methoxysilicon end groups and its application in a nano‐SiO2 aqueous system

In order to improve the dispersity and stability of the nano‐SiO₂ aqueous system with high solid content, a kind of polyacrylic acid dispersant with methoxysilicon end groups (KH590‐PAA) was synthesized by photopolymerization of acrylic acid (AA) initiated with (3‐mercaptopropyl)trimethoxysilane (KH590). After adding KH590‐PAA into the nano‐SiO₂ aqueous dispersion system (20 wt% solid content), the viscosity and the curing time of the system were measured with a rotational viscometer and the inverted bottle method. Moreover, the dispersion mechanism of KH590‐PAA for the nano‐SiO₂ aqueous system was researched by measuring the adsorption capacity, the particle size and the zeta potential of the nanoparticles with a conductivity meter, dynamic light scattering, SEM and TEM, respectively. The results showed that the methoxysilicon groups in KH590‐PAA could react with hydroxyl groups on the surface of nano‐SiO₂ in the process of stirring, which enhanced the adsorption capacity of the dispersant and then increased the surface charge of the particles. Therefore, electrostatic repulsion and steric hindrance effects between the SiO₂ nanoparticles could be further enhanced by adding the KH590‐PAA dispersant, and then the nano‐SiO₂ aqueous system exhibited better dispersity and stability. Besides, the dispersion properties of SiO₂ nanoparticles in water were closely related to the addition amount and the molecular weight of the KH590‐PAA dispersant. © 2018 Society of Chemical Industry     

气瓶内部淬火过程的流动换热特性

 大直径厚壁气瓶内部淬火时的流动换热过程极其复杂，受到多种因素的影响，而研究气瓶内部压强和温度的变化规律对改善流动换热效果、提高产品组织性能具有重要的理论指导意义。以914 mm厚壁气瓶和瓶内流体为研究对象，建立了二维等效流 固耦合模型；采用多喷嘴系统对气瓶内外进行喷水淬火，研究了气瓶总长、喷水流速及淬火时间对瓶内压强及内壁温度的影响，通过间歇淬火试验验证了数学模型的正确性。结果发现，气瓶长度对瓶内压强和瓶壁温度的影响显著，喷水流速次之，当喷水流速大于8 m/s后，水量对瓶壁的冷却效果大大降低；气瓶内壁长度方向的温度梯度分别随气瓶总长的增加和淬火时间的延长而减小，但基本不受喷水量的影响。     

Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Coal-based ethanol production by hydration of ethylene is limited by the low equilibrium ethylene conversion at elevated temperature. To improve ethylene conversion, coupling hydration of ethylene with a potential ethanol consumption reaction was analyzed thermodynamically. Five reactions have been attempted and compared: (1) dehydration of ethanol to ethyl ether ({\mathrm{2C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}\mathrm{OH}\iff{\mathrm{C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{OC}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{+H}}_{\mathrm{2}}\mathrm{O}), (2) dehydrogenation of ethanol to acetaldehyde ({\mathrm{C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}\mathrm{OH}\iff {\mathrm{CH}}_{\mathrm{3}}{\mathrm{CHO+H}}_{\mathrm{2}}), (3) esterification of acetic acid with ethanol ({\mathrm{C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{OH+CH}}_{\mathrm{3}}\mathrm{COOH}\iff {\mathrm{CH}}_{\mathrm{3}}{\mathrm{COOC}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{+H}}_{\mathrm{2}}\mathrm{O}), (4) dehydrogenation of ethanol to ethyl acetate ({\mathrm{2C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}\mathrm{OH}\iff {\mathrm{CH}}_{\mathrm{3}}{\mathrm{COOC}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{+2H}}_{\mathrm{2}}), and (5) oxidative dehydrogenation of ethanol to ethyl acetate ({\mathrm{2C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{OH+O}}_{\mathrm{2}}\iff {\mathrm{CH}}_{\mathrm{3}}{\mathrm{COOC}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}{\mathrm{+2H}}_{\mathrm{2}}\mathrm{O}). The equilibrium constants and equilibrium distributions of the coupled reactions were calculated and the effects of feed composition, temperature and pressure upon the ethylene equilibrium conversion were examined. The results show that dehydrogenation of ethanol to acetaldehyde has little effect on ethylene conversion, whereas for dehydrogenation of ethanol to acetaldehyde and ethyl acetate, ethylene conversion can be improved from 8% to 12.8% and 18.5%, respectively, under conditions of H₂O/C₂H₄ = 2, 10 atm and 300°C. The esterification of acetic acid with ethanol can greatly enhance the ethylene conversion to 22.5%; in particular, ethylene can be actually completely converted to ethyl acetate by coupling oxidative dehydrogenation of ethanol.     

考虑流固耦合的管道机器人冲击环焊缝过程动力学建模与分析

以管道机器人（Pipeline inspection gauge，PIG）为载体的内检测技术是保障油气管道安全运输的重要手段。针对管内高压流体作用下，管道机器人在冲击管内环焊缝过程中产生的动力学行为突变问题。建立了管道周向受限空间中基于Kelvin弹簧阻尼的管道机器人密封盘等效动力学模型，结合管道机器人本体建立了多体系管道机器人动力学模型；详细推导了管道机器人轴向振动微分方程，以及管内流体的流动方程；并使用Matlab/Simulink与Adams进行流固耦合仿真，作为重要的工艺参数之一，研究了管道机器人速度改变时，其在冲击环焊缝过程中的动力学响应情况。结果表明：所建立的密封盘及管道机器人动力学模型能够很好地表征密封盘在管道轴向、径向以及周向的力学特性；运行速度越快，管道机器人通过环焊缝引起的轴向振动越剧烈，冲击振动越明显；而垂向和俯仰振动现象随运动速度增大而显著减弱。     

BHDDF350型联轴器失效分析及改进设计

联轴器在旋转过程中连续传递扭矩且具备一定缓冲和减振的保护作用,而又不改变初始旋转方向和扭矩大小,BHDDF350型联轴器是某型矿用减速机与电机之间的扭矩传动部件。从该型联轴器的运行工况、结构分布、损坏形式等方面查找并分析了其失效原因,依据其受力分析提出了改进型设计方案,以供业内参考。改进设计后的联轴器,弹性块受力均匀,且最大受力降比30%以上,可有效延长联轴器的整体使用寿命,减少了煤矿井下日常的维护工作量。     

铜基化合物的可见光催化研究进展

与传统贵金属光催化剂相比，铜基光催化剂具有价格低廉、绿色环保、反应条件温和、光催化活性可调节等优势，受到合成化学家们广泛关注。本文简述了铜基催化剂的光催化历史，回顾了近五年来铜基化合物在可见光催化领域的研究成果与进展，总结了铜基催化剂的独立光催化机理与协同光催化机理；简要阐述了铜催化剂在不同类型反应中的应用，重点讨论了铜(Ⅰ)催化剂在烯烃官能化、碳-碳偶联、碳-杂偶联、原位催化等反应中的应用研究，表明铜基化合物在光催化合成领域具有很大的应用潜力。对未来的研究工作进行了展望，指出拓展催化剂的反应适用性、探索催化剂的氧化还原能力、进一步开发催化剂在手性合成中的应用将是该领域的研究重点。     

Synthesis of Cellulose-Based Macromolecular Coupling Agent and its Utilization in Poly (butylene succinate)/Wood Flour Composites

A long fatty side chain was introduced into the macromolecule of hydroxyethyl cellulose (HEC) via esterification reaction. The hydrophobicity of hydroxyethyl cellulose lauric acid ester (HECLAE) was enhanced in comparison with HEC. The obtained HECLAE was used as macromolecular coupling agent in poly (butylene succinate)/wood flour composites and exhibited a positive influence on improving the mechanical performance of composites. Besides, HECLAE plays a role as a hydrophobic agent in composites. A significant increase in storage modulus (E’) was observed upon the incorporation of treated wood flour. SEM images showed that the dispersion of treated wood flour in PBS matrix was improved.