微米级可降解性高吸水树脂微球的制备工艺

以淀粉与丙烯酸(AA)/丙烯酰胺(AM)为原料,采用接枝共聚的方法,在低油水比的反相悬浮体系中制备微米级可降解高吸水树脂微球,探讨了油水比、中和度、分散剂、引发剂、交联剂对树脂性能的影响.结果表明,对产物的粒径和吸水倍率影响程度由大到小依次为:丙烯酸中和度、油水比、分散剂用量、引发剂用量、交联剂用量.研究得到的最佳工艺条件为:丙烯酸中和度0.7,油水比2.5∶1,分散剂用量0.7g,引发剂用量(占单体总质量)0.3%,交联剂用量(占单体总质量)0.057%;得到产物的粒径约为1.5μm,吸水倍率为290.93g/g.     

A study on the thermal conductivity of resilient materials

The floor system of apartments must have a certain level of floor impact sound performance (light-weight impact sound is 58 dB or less, heavy-weight impact sound is 50 dB or less), and comply with the building energy code to prevent energy loss in residential buildings in Korea. In this study, expanded polystyrene (EPS), expanded polypropylene (EPP), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE) and urethane foam, which are widely used in Korea as resilient materials for floating floor system of apartments, were measured. Their thermal conductivity and apparent density were measured to analyze their thermal properties and their relation was analyzed by material. In case of resilient materials made of EPS and EPP, thermal conductivity tended to decrease as apparent density increased, whereas in case of resilient materials made of EVA and PE, as apparent density increased, thermal conductivity tended to increase as well.     

绝对吸收式激光能量计高准确度校准技术研究

采用量热法的高能激光能量计用于测量能量大于50 kJ的连续波高能激光能量,通常用已知功率的连续激光开展激光能量计的光电校准需要激光照射时间超过20 min,而由于热损失等原因,进行长时间激光能量校准时,校准不确定度高达12%。以量热式平面吸收高能激光能量计为模型,从理论上分析了热辐射、热对流对连续波高能激光能量测量结果的影响,得到了较准确的平面吸收腔激光能量计冷却数学模型,实现了能量计热损失补偿,并通过建立相应的实验装置验证了该模型,用其对装置的测量结果加以修正,可使光电校准的测量不确定度减小到1%以下。     

纳米级MnO_2的制备与电化学性质研究(Ⅱ)溶胶凝胶法制备掺铋改性纳米MnO_2的性能

用溶胶凝胶法制得掺铋二氧化锰．经XRD、TEM、ICP、化学分析等测定，确定了所得样品的主要晶型为α－MnO2，所掺铋的晶态为Bi2O3,为纳米级颗粒（记为um－Bi-CMD）．用它与掺铋电解二氧化锰（记为Ci-EMD）以最佳配比混合，可大大提高充放电容量．通过循环伏安、交流电导率、交流电阻等测试所测得的电导率、电极表面的分形维数，初步解释了了充入电性能改善的原因主要是由于提高了最佳配比样品的导电率，降低了混合样品的晶界电阻，使制得的电极表面粗糙度增大，稳定了电极表面结构．     

Measurement of liquid film in microchannels using a laser focus displacement meter

This paper presents a new method for measuring the interfacial displacement of a liquid film in microchannels using a laser focus displacement meter (LFD). The purpose of the study is to clarify the effectiveness of the new method for obtaining detailed information concerning interfacial displacement, especially in the case of a thin liquid film, in microchannels and minichannels. To prevent the tube wall signal from disturbing that of the gas–liquid interface, a fluorocarbon tube with a water box was used; the refraction index of this device is the same as that for water. With this method, accurate instantaneous measurements of the interfacial displacement of the liquid film were achieved. The error caused by refraction of the laser beam passing through the acrylic water box and fluorocarbon tube was estimated analytically and experimentally. The formulated analytical equation can estimate the real interface displacement by using the measured displacement in a fluorocarbon tube of 25 m to 2.0 mm I.D. A preliminary test using fluorocarbon tubes of 1 mm and 2 mm I.D. showed that the corrected interface displacement calculated by the equation agreed with the real displacement to within a 1% margin of error. It was also confirmed that the LFD in the system could measure a liquid film of 0.25 m at the thinnest. We made simultaneous measurements of the interface in fluorocarbon tubes of 0.5 mm and 1 mm I.D. using the LFD and a high-speed video camera with a microscope. These showed that the LFD could measure the interface of a liquid film with high spatial and temporal resolution during annular, slug, and piston flow regimes. The data also clarified the existence of a thin liquid film of less than 1 m in thickness in the slug and annular flow regimes.     

取样量对润滑油中微量水分检测结果的影响

研究取样量对润滑油中微量水分测定结果的影响。基于卡尔·费休滴定法,在选定的测量条件下,用发生电极为有隔膜的自动库仑水分仪对基础油、有机热载体油、压缩机油、膨胀机油等新油和发动机油、汽轮机油、涡轮机油、压缩机油、齿轮油、液压油、导热油、船用油、电器绝缘油、风动工具油、金属加工油等在用油在0.1~2.0 g内各取9组不同质量的样品进行测定,得到了润滑油中微量水分准确测定所需的取样量。实验结果表明,新油取样量大于1.0 g,在用油取样量在1.0~1.5 g范围内,可以准确测定润滑油中微量水分含量。测定结果的相对标准偏差为0.83%~3.51%(n=10),样品加标回收率为95.0%~103.0%。在选择的取样量下,该方法具有良好的精密度、准确度,可连续测定多个样品,满足测定需求。     

Experimental study on axial development of liquid film in vertical upward annular two-phase flow

Accurate measurements of the interfacial wave structure of upward annular two-phase flow in a vertical pipe were performed using a laser focus displacement meter (LFD). The purpose of this study was to clarify the effectiveness of the LFD for obtaining detailed information on the interfacial displacement of a liquid film in annular two-phase flow and to investigate the effect of axial distance from the air–water inlet on the phenomena. Adiabatic upward annular air–water flow experiments were conducted using a 3 m long, 11 mm ID pipe. Measurements of interfacial waves were conducted at 21 axial locations, spaced 110 mm apart in the pipe. The axial distances from the inlet (z) normalized by the pipe diameter (D) varied over z/D = 50–250. Data were collected for predetermined gas and liquid flow conditions and for Reynolds numbers ranging from Re_G = 31,800 to 98,300 for the gas phase and Re_L = 1050 to 9430 for the liquid phase. Using the LFD, we obtained such local properties as the minimum thickness, maximum thickness, and passing frequency of the waves. The maximum film thickness and passing frequency of disturbance waves decreased gradually, with some oscillations, as flow developed. The flow development, i.e., decreasing film thickness and passing frequency, persisted until the end of the pipe, which means that the flow might never reach the fully developed state. The minimum film thickness decreased with flow development and with increasing gas flow rate. These results are discussed, taking into account the buffer layer calculated from Karman’s three-layer model. A correlation is proposed between the minimum film thickness obtained in relation to the interfacial shear stress and the Reynolds number of the liquid.     

用硅光电池制作光功率计实验

介绍使用运算放大器以及硅光电池制作光功率计的原理以及制作的过程。实验涉及到运算放大器以及硅光电池光谱响应等基础知识。     

多路电度表误差检测系统

本文报道了单片微机在电度表误差检测中的应用成果,介绍单片微机控制的多路电度表误差检测系统的功能、硬件结构和软件设计。     

在线红外水分仪的一种校准方法

用动态被测物料作为校准介质,再用重量法对选取的样品定值,以此校准在线红外水分仪。