Influence of charged droplet cloud on flashover of air gaps for lightning impulse voltage

Transmission lines passing through a mountainous region often are struck by winter lightning. As a result, numerous double-circuit faults occur. Space charge might be responsible for this phenomena. Several investigations on flashover characteristics have been performed focusing on reduction of flashover voltage due to ionic space charge formed by corona discharge. In this paper, flashover characteristics of an air gap within a charged droplet cloud ejected from an airless nozzle using an induction charging method are discussed. The droplets are charged in the range -200 to 200 μC/kg, forming the space-charge density of approximately 13 μC/m³. The flashover voltage and the time lag to flashover were measured when 1.2 × 50 μs lightning impulse voltage applied to a rod-sphere gap is placed within the charged cloud. Flashover voltage for a positive rod increased markedly within a positive charged cloud by increasing the charge-to-mass ratio. The increase of flashover voltage was up to 80 percent in comparison with uncharged droplets. Flashover voltage for the negative rod decreased about 20 percent in the cloud of either polarity. The results show that the presence of charged droplets in the air gaps affects the discharge process significantly.     

Temperature‐induced surfactant‐ mediated pre‐concentration of uranium assisted by complexation

Cloud‐point extraction (CPE) was used with lipophilic chelating agent to extract uranium(VI) from aqueous solutions. The methodology used is based on the formation of metal complexes soluble in a micellar phase of a non‐ionic surfactant, Triton X‐114. The metal ions complexes are then extracted into the surfactant‐rich phase at a temperature above the cloud‐point temperature. The influence of surfactant concentration on extraction efficiency was studied and the advantage of adding 8‐hydroxyquinoline (8HQ) as lipophilic chelating agent was evidenced. High extraction efficiency was observed, indicating the feasibility of extracting U(VI) using CPE. This study describes a four‐step process—(1) extraction, (2) thermo‐induced phase splitting, (3) back‐extraction and (4) second phase splitting—for the recovery of uranium from water. In our conditions, the extraction yield is quantitative and the concentration factor obtained is superior to 100. After stripping with a diluted nitric acid solution (pH < 1), the system can be recycled through a new four‐step cycle. Copyright © 2006 Society of Chemical Industry     

Direct extraction of phenylacetic acid from immobilised enzymatic hydrolysis of penicillin G with cloud point extraction

The enzymatic hydrolysis of potassium salt of penicillin G (Pen G) into phenylacetic acid (PAA) and potassium salt of 6‐aminopenicillanic acid (APA) is inhibited not only by the substrate and the product APA but also by the by‐product PAA. The partitioning behaviour of PAA in a cloud point system, a novel two‐phase partitioning system, was determined. Direct extraction of PAA in the process of immobilised penicillin acylase hydrolysis of Pen G without pH control was achieved. Pen G was hydrolysed almost completely and the product APA concentration in the cloud point system was much higher than in the control, suggesting that the cloud point system may be applied as a novel extractive bioreactor for the enzymatic hydrolysis of Pen G. Copyright © 2006 Society of Chemical Industry     

云参数和可降水总量的同步物理反演方法试验

利用改进的同步物理反演方法计算东亚地区的云参数和可降水总量,并用气象卫星短、长波窗区通道亮度温度差对反演结果进行真实性检验.结果表明:该反演算法的效果是好的.     

H型钢结构工业厂房施工技术

通过几个H型钢结构工业厂房的施工实践，介绍了H型钢结构的组成及工艺特点，就H型钢构件的制作、安装等问题进行了分析探讨，为类似工程积累了丰富的施工经验。     

乳品厂新型CIP自动控制系统

为了顺应国内乳品厂原地清洗(CIP)工艺的不断发展，研制了新一代基于PLC控制器的CIP设备控制系统，本文介绍了该系统的原理、组成及应用。     

表面安装和高密度印制线路板

当今电子，通信产品日新月异，要求电路板高密度组装，安装方式由表面实地以代通孔插装已 历史的必然，因此，印制板技术正向高密度多层化方向飞速发展。文中介绍电子元器件和装配方法演变，电路板方式种类表面安装用印制板的特点，实现印制板高密度多层化的方法，印制板安装密度的选择，评估，认定印制板委托加工的要素以及现今印制板一般加工范围。     

Pseudo-Satellitefilm Using Fractal Clouds to Enhance Animated Weather Forecasting

We have developed a system enabling the National German Meteorological Office to generate pseudo-satellite images and video sequences based on their weather forecasting simulation data. With our system meteorologists can visualize the past and the current weather situation, evaluate their simulation results, and produce animated weather forecast videos broadcasted by several television stations. Realistic images are generated by interpolating the extremely coarse weather simulation data grid and enhancing the result using fractal clouds. It also enables the meteorologists to interactively change the forecast data in order to compensate the lack of accuracy or the known errors in their simulation models. Our system TRITON enables the visualization of complex weather simulations in a more natural way by presenting an intuitively understandable forecast.     

装置参数对FAE云雾状态的影响

本实验研究了壳体材料、比药量和长径比等装置参数对燃料空气炸药（FAE）云雾状态的影响。结果表明：钢质壳体更利于云雾的径向分散；适当的比药量可形成最优化的云雾尺寸和调节云雾内部浓度；长径比不是云雾最终状态的决定因素。     

异构脱蜡润滑油基础油中絮状物组成的研究

某些异构脱蜡重质润滑油基础油，在室温下，放置一定时间后，常有絮状物从油中析出。为了研究异构脱蜡油絮状物生成的原因，将异构脱蜡油中的絮状物分离出来，并以模拟蒸馏、测定平均相对分子质量、质谱(MS)和核磁共振(^13C-NMR)等方法进行分析。结果表明，絮状物主要是由具有较长碳链、凝固点较高的蜡状分子，特别是链状或异构化程度较低的烷烃分子组成。