Highly accurate SNR measurement using the covariance of two SEM images with the identical view

Quality of an SEM image is strongly influenced by the extent of noise. As a well-known method in the field of SEM, the covariance is applied to measure the signal-to-noise ratio (SNR). This method has potential ability for highly accurate measurement of the SNR, which is hardly known until now. If the precautions discussed in this article are adopted, that method can demonstrate its real ability. These precautions are strongly related to "proper acquisition of two images with the identical view," "alignment of an aperture diaphragm," "reduction of charging phenomena," "elimination of particular noises," and "accurate focusing," As necessary, characteristics in SEM signal and noise are investigated from a few standpoints. When using the maximum performance of this measurement, SNR of many SEM images obtained in a variety of the SEM operating conditions and specimens can be measured accurately.     

脱胶工艺对不同段棉秆皮纤维性能的影响

定量测定棉秆皮各段成分含量,并采用化学二煮法脱胶方法对棉秆皮进行分段脱胶.以棉秆皮纤维细度、残胶率、断裂强度为指标,研究脱胶处理对提取的不同段棉秆皮纤维性能的影响.结果表明,在同一脱胶工艺条件下,不同段棉杆皮纤维的细度、残胶率、断裂强度有较大差异,棉秆皮应采用分段脱胶处理.合理的棉秆皮脱胶分段方案为：第一段根部,地表以下部分;第二段中段,地表以上长度25cm;第三段稍部,地表以上长度大于25cm.     

ClO_2预氧化处理联苯胺生产废水的研究

采用ClO2氧化法对联苯胺生产废水进行预处理,运行结果表明：当进水的COD及联苯胺平均分别为1646mg/L和38.3 mg/L时,出水平均分别为95.8 mg/L和0.603 mg/L,出水优于GB8978-1996中的一级排放标准,处理效果稳定。     

单通道TD-SCDMA射频拉远单元

该文设计了一种单通道TD-SCDMA射频拉远单元。首先根据系统要达到的性能指标要求,设计了系统拓扑结构,接着从该系统拓扑结构出发,分析了整个系统的设计思路及实现方案,选择相应的电路模块。测试结果表明设计的系统达到了预期的指标,临近通道功率比小于-40.64 dBc和误差向量幅度为5.08%rms。     

紫苏调和油的黄金比例模型及生产配方

以中国营养学会提出的黄金比例为标准,分析国内油脂资源以及居民饮食习惯,建立以紫苏油为主的黄金比例调和油的数学模型,给出以紫苏油为主体的黄金比例调和油的配方,及其成本分析,另外根据不同的消费群体,修改模型参数,就可以得到适合的配方.     

延边大学朝鲜族女大学生身体成分与身体形态现状分析

对延边大学朝鲜族和其他民族女大学生的身体形态（身高、体重、三围）和身体成分（体重指数、体脂率、腰臀比）进行了比较研究.结果表明：朝鲜族女生的超重和高于正常体脂检出率略高于其他民族,而汉族女生的体重偏低比例略高于朝鲜族和其他少数民族,但均无显著性差异;朝鲜族女生的向心性肥胖比例略高于其他民族,但均无显著性差异;汉族女生的未达腰臀比切点比例高于朝鲜族,具有显著性差异;汉族和其他少数民族女生的身高、体重、臀围均值明显高于朝鲜族,具有显著性差异,但朝鲜族女生的腰臀比均值明显高于汉族,具有显著性差异;朝鲜族女生的体重指数（BMI）和体脂率均值虽然略高于其他民族,但无显著性差异;朝鲜族女生的平均身高略低于全国同龄组女生均值,且超重和肥胖检出率均低于全国同龄组女生检出率.     

钛白副产硫酸亚铁制备超细透明氧化铁黄研究

以钛白粉厂副产物硫酸亚铁为原料,以氨水为沉淀剂,采用空气氧化法制备超细透明氧化铁黄.分别研究了影响晶种形成和晶体生长的主要影响因素.通过优化实验,得出了最佳工艺条件.晶种制备阶段：温度为30℃,空气流量为2L/min,溶液的pH为4～6,搅拌速度为400r/min,Fe2＋浓度为1mol/L.晶体生长阶段：温度为85℃,空气流量为2L/min,溶液pH为4～6.     

空气源热泵热水系统的优化设计选择

空气源热泵热水供应是一种高效的建筑节能方式,被广泛地应用于公共建筑卫生热水供应系统。研究了热泵机组的出水规律和用户的用水规律,通过建立全寿命周期成本计算数学模型,对不同名义制热量的热泵机组进行经济效果综合评价,寻找最佳的技术经济点,为设备选型与计算、储热水箱最佳容积的确定,提供参考依据。     

Airflow characteristics by air curtain jets in full-scale room

A new air distribution pattern, air curtain jet ventilation was presented. The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail. To identify the airflow characteristics of this novel air curtain jet ventilation system, a full-scale room was used to measure the jet velocity with a slot-ventilated supply device, with regards to the airflow fields along the vertical wall as well as on the horizontal floor zones. The airflow fields under three supply air velocities, 1.0, 1.5 and 2.0 m/s, were carried out in the full-scale room. The experimental results show the velocity profiles of air distribution, the airflow fields along the attached vertical wall and the air lake zones on the floor, respectively. The current experimental research is helpful for heating, ventilation and air conditioning (HVAC) engineers to design better air distribution in rooms.