虚拟专用网实现矿区计算机网络安全连接

针对煤炭企业矿区地理位置分布偏远所带来的网络安全连接的问题,提出利用IPSec安全协议实现2个矿区之间跨越因特网的企业内部网络连接方案,运用虚拟专用网内部网关策略控制体系,对发送端原始的数据经过高强度、动态变换的密钥封装在另一个IP通道内,通道头部地址为接收端的IP地址,以此来保证数据的安全性,以达到煤炭企业网络安全扩展的目的.并对企业矿区之间网络出口存在网络地址转换设备,导致两地网络间安全数据隧道无法连接的问题提出了有效的解决方法.     

等离子体浸没式离子注入沉积技术及应用

等离子体浸没式离子注入沉积是近年来迅速发展的一种材料表面改性新技术,其基本原理是,作为靶的工件外表面全部浸没在低气压、高密度的均匀等离子体中,工件上施加频率为数百赫兹、数千至数万伏高压负脉冲偏压.它克服了传统方法所具有的薄膜沉积或离子注入存在方向性的固有缺陷,因此在复杂形状的三维工件表面改性工艺与技术上表现出无与伦比的优越性.该技术可以有多种工作模式,在离子注入前、注入期间或注入后进行原位清洗、刻蚀或薄膜沉积.作为应用实例,本文给出在复杂形状构件上合成均匀类金刚石或纳米金刚石薄膜的实验结果,最后指出等离子体浸没式离子注入沉积技术的发展趋势和工业化应用尚需解决的问题.     

Centrifugal compressor blade optimization based on uniform design and genetic algorithms

An optimization approach to centrifugal compressor blade design, incorporating uniform design method (UDM), computational fluid dynamics (CFD) analysis technique, regression analysis method and genetic algorithms (GA), is presented. UDM is employed to generate the geometric information of trial samples whose performance is evaluated by CFD technique. Then, function approximation of sample information is performed by regression analysis method. Finally, global optimization of the approximative function is obtained by genetic algorithms. Taking maximum isentropic efficiency as objective function, this optimization approach has been applied to the optimum design of a certain centrifugal compressor blades. The results, compared with those of the original one, show that isentropic efficiency of the optimized impeller has been improved which indicates the effectiveness of the proposed optimization approach. __________ Translated from Journal of Power Engineering, 2007, 27(5): 713–716 [译自: 动力工程]     

Numerical analysis of rotating stall characteristics in vaneless diffuser with large width-radius ratio

A two-dimensional model, where the influence of wall boundary layers is neglected and inlet jet-wake velocity patterns are prescribed, was applied to simulate one vaneless diffuser with a large width-radius ratio. The impact of diffuser length, impeller blade number, etc. on the rotating stall was analyzed. Computational results show that a different mechanism does exist for diffusers with large width-radius ratios. Comparison with related conclusions and references is supportive of the model.     

Centrifugal compressor blade optimization based on uniform design and genetic algorithms

An optimization approach to centrifugal compressor blade design, incorporating uniform design method (UDM), computational fluid dynamics (CFD) analysis technique, regression analysis method and genetic algorithms (GA), is presented. UDM is employed to generate the geometric information of trial samples whose performance is evaluated by CFD technique. Then, function approximation of sample information is performed by regression analysis method. Finally, global optimization of the approximative function is obtained by genetic algorithms. Taking maximum isentropic efficiency as objective function, this optimization approach has been applied to the optimum design of a certain centrifugal compressor blades. The results, compared with those of the original one, show that isentropic efficiency of the optimized impeller has been improved which indicates the effectiveness of the proposed optimization approach.     

Optimal design of an experimental methanol fuel reformer

We report on the steady state modeling of an experimental methanol fuel reformer for fuel cell applications. The fuel reformer consists of an AutoThermal Reformer (ATR) followed by an Oxygen Removal (OR) reactor, Steam Reformer (SR) and Water Gas Shift (WGS) reactor. The effluent from the WGS is fed to a series of three Preferential Oxidation (PROX) reactors that reduce the CO concentration to less than 40 ppm. A mathematical model of the reformer is developed and selected parameters of the model are fit to experimental data collected from a fuel reformer that was designed, built and operated by the Material and Chemical Research Laboratories (MCL) of the Industrial Technology Research Institute (ITRI) in Hsinchu, Taiwan. In order to develop a compact and high-performance fuel reformer system, the mathematical model is used to design a reformer that has the minimum possible combined volume of the steam reformer and water gas shift reactor. The result is that the volume of the optimized reactor units can be reduced by 17.2% without a significant change in the overall efficiency.     

Planar array stack design aided by rapid prototyping in development of air-breathing PEMFC

The polymer electrolyte membrane fuel cell (PEMFC) is one of the most important research topics in the new and clean energy area. The middle or high power PEMFCs can be applied to the transportation or the distributed power system. But for the small power application, it is needed to match the power requirement of the product generally. On the other hand, the direct methanol fuel cell (DMFC) is one of the most common type that researchers are interested in, but recently the miniature or the micro-PEMFCs attract more attention due to their advantages of high open circuit voltage and high power density.     

Significantly enhanced charge conduction in electric double layer capacitors using carbon nanotube-grafted activated carbon electrodes

Carbon nanotube (CNT)-grafting by chemical vapor deposition was conducted to reduce the resistance of activated carbon fiber serving as an electrode for electric double layer capacitors. Sputtering deposition of Ni catalyst particles led to a uniform growth of CNTs on the carbon fiber surface through the tip-growth mechanism. Because sputtering deposition ensures little pore blockage (in comparison with wet-impregnation), the surface area decrease of the carbon fiber due to Ni loading was minimized. By using H₂SO₄ aqueous solution as the electrolyte, a capacitor cell assembled with the CNT-grafted fiber showed higher electron and electrolyte-ion conductivities relative to a cell assembled with the bare fiber. By increasing the discharging current density from 1 to 150 mA cm⁻², the bare fiber exhibited a capacitance loss of 17% while the CNT-grafted fiber showed a mitigated capacitance loss of only 7%. This developed CNT-grafting technique renders activated carbon fiber a promising electrode material for a variety of electrochemical applications.     

辐射硫化和增容剂对氯丁／聚丙烯酸钠遇水膨胀橡胶性能的影响

采用γ射线辐射硫化技术制备了氯丁/聚丙烯酸钠遇水膨胀橡胶,考察了在一定吸收剂量时增容剂对膨胀橡胶的力学性能、膨胀性能和质量损失率的影响,以及吸收剂量对质量损失率的影响.结果表明,增容剂有利于提高力学和膨胀性能,降低质量损失率,吸收剂量提高有利于质量损失率的降低.     

平整机吹扫系统的改造与优化

针对济钢冷轧板厂平整机组冷轧板残存平整液斑缺陷的问题,对平整机吹扫系统的结构及存在问题进行了分析,并采取了针对性的解决措施.采用优化措施后,吹扫效果良好,带钢表面质量明显提高,平整液斑缺陷大幅度减少.