复合绝缘子微间隙大小对电场分布的影响

复合绝缘子因长久运行或工艺缺陷等原因可能存在微间隙,这种微间隙的存在使局部电场发生畸变,使微间隙内发生电离,进一步可能发展为局部放电。带电金具与芯棒、伞裙护套之间微间隙放电会直接腐蚀芯棒,老化、腐蚀伞裙护套,降低芯棒的机械性能,引起芯棒脆裂、掉线,从而造成重大停电事故。对复合绝缘子存在微间隙时伞裙电场进行初步探讨,结果表明微间隙的存在使间隙局部场强分布发生严重畸变,金具处最大场强变大,微间隙附近处伞裙以及微间隙内部场强随着间隙增大局部畸变变得严重,但是微间隙的存在与否,对伞裙整体上的电位、电场分布影响不甚明显。     

Synthesis of LiNi0.9Co0.1O2 from Li2CO3, NiO or NiCO3, and CoCO3 or Co3O4 and their electrochemical properties

Cathode active materials with a composition of LiNi_0.9Co_0.1O₂ were synthesized by a solid-state reaction method at 850 °C using Li₂CO₃, NiO or NiCO₃, and CoCO₃ or Co₃O₄, as the sources of Li, Ni, and Co, respectively. Electrochemical properties, structure, and microstructure of the synthesized LiNi_0.9Co_0.1O₂ samples were analyzed. The curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂ for the first charge–discharge and the intercalated and deintercalated Li quantity Δx were studied. The destruction of unstable 3b sites and phase transitions were discussed from the first and second charge–discharge curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂. The LiNi_0.9Co_0.1O₂ sample synthesized from Li₂CO₃, NiO, and Co₃O₄ had the largest first discharge capacity (151 mA h/g), with a discharge capacity deterioration rate of −0.8 mA h/g/cycle (that is, a discharge capacity increasing 0.8 mA h/g per cycle).     

再论水泥工业可持续发展的"四零一负"战略

我国水泥工业的可持续发展应该朝着“四零一负”的目标发展,即水泥企业对其周围生态环境完全达到零污染;水泥熟料生产企业对外界电能的零消耗;水泥企业对废料、废渣、废水的零排放;熟料生产对天然矿物燃料(煤、油、天然气)的零消耗;水泥企业对全社会废料、废渣的负增长作出应有的贡献。科学技术的进步和实践证明,这一目标离我们不是太远。     

电解液添加剂苯基丙二酸对电池持续放电时间影响的研究

采用恒流放电和定电压充电的电化学方法研究了苯基丙二酸添加剂对改善铅酸电池放电持续时间的影响,初步探讨了添加剂的可能作用机理.通过多组对比实验结果的分析和研究后认为:适量苯基丙二酸用作电解液添加剂的加入可以提高电池的放电持续时间.     

Enhanced lithium-ion intercalation properties of coherent hydrous vanadium pentoxide-carbon cryogel nanocomposites

Coherent hydrous vanadium pentoxide (V₂O₅·nH₂O)-carbon cryogel (CC) nanocomposites were synthesized by electrodeposition of vanadium pentoxide onto the porous carbon scaffold which was derived from resorcinol (R) and formaldehyde (F) organic hydrogels. As-fabricated nanocomposites were characterized by scanning electron microscopy (SEM), along with EDAX and nitrogen sorption isotherms which suggested vanadium pentoxide incorporated in the pores of carbon cryogels. The nanocomposites showed much improved discharge capacity and better cyclic stability as compared to hydrous vanadium pentoxide films deposited on platinum foil. The discharge capacity of the nanocomposites reached 280 mAh g⁻¹ based on the mass of the vandium pentoxide at a current density of 100 mA g⁻¹ and it possessed good cycle stability at different discharge rates. The results demonstrated that electrochemical performances, such as specific discharge capacitance and reversibility of the composite electrode, could be greatly enhanced by the introduction of carbon cryogels (CCs) scaffold with three-dimensionally interconnected porous structure in which V₂O₅·nH₂O homogeneously dispersed.     

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将清洁燃料(天然气)的利用与环境结合起来进行研究，是当今世界的前沿科学技术。为了具体说明从天然气开采到使用整个过程中对环境产生的影响，采用生命周期分析的方法对天然气开采、运输、使用等三个阶段中所造成的废弃物排放进行了分析和计算，对整个过程中投入和产出的能量进行了计算，并对天然气合成氨、作为民用燃气、发电、热电联产等天然气利用方法进行了比较。结果表明：与煤、石油等传统能源相比，天然气在各个方面对环境的影响是最小的，是一种理想的清洁能源。     

石镇街站“95.6”洪水最大洪峰流量浅析

根据现有资料的粗浅分析表明，“９５．６”洪水实测最大洪峰流量明显偏大。通过进一步分析得出较为合理的结果，这对流量整编定线提供依据以及规划设计有应用均有一定的实际意义。     

一个特殊的设计洪水流量过程线放制方法介绍

为满足水利水电工程的防洪要求，需进行设计洪水的计算，其中选择典型洪水过程线，由于条件所限，一般常用的典型洪水过程线放制方法所得过程线，不能真正代表工程所在流域的洪水特性，本文探讨某些特殊情况下，对典型线进行修改的必要性和修改方法。     

Deterministic and stochastic assessment of the harmonic currents consumed by discharge lamps

The paper examines the deterministic and stochastic behavior of magnetic ballast discharge lamps. Expressions to deterministically calculate the harmonic currents of discharge lamps are provided and analytical expressions of the probability density functions of these harmonic currents are obtained. The results are validated with experimental measurements.     

The effect of blade angle on the flow and pressure distributions in the vicinity of the diffuser blades of a room air conditioner

Many studies on air-conditioning systems are more focused on the individual thermal comfort rather than the thermal efficiency, due to an increase in health concerns. There are several factors influencing the thermal comfort, such as temperature, humidity, convection and air movement, etc. Numerical analyses were performed to investigate the effect of blade angle on the flow characteristics in the vicinity of diffuser blades of a room air conditioner (RAC), with three different blade discharge angles of 45.1°, 58.6° and 116°. We used the commercial code FLUENT to calculate the two-dimensional steady thermal flow fields with different impeller rotational velocities. The angular velocities were located within the range from 900 rpm to 1200 rpm. Turbulence closure was achieved using a standard k-ɛ model. A moving reference frame (MRF) approach was adopted to simulate the flow field generated by the impeller in an RAC. The results were graphically depicted with various geometrical configurations and operating conditions. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Youn-Jea Kim received his B.S. degree in Mechanical Engineering from Sungkyunkwan University, Korea, in 1982. He then received his M.S. and Ph.D. degrees from the State University of New York at Buffalo in 1987 and 1990, respectively. Dr. Kim is currently a Professor at the School of Mechanical Engineering at Sungkyunkwan University in Korea. Dr. Kim’s research interests include gas dynamics, MEMS, and fluid-machineries, etc.