架空屏蔽电缆–大地耦合的感应电流谐振分析

为了从理论上分析计算空间电磁场耦合在电缆上产生的感应电流,基于架空屏蔽电缆–大地回路的有源传输线模型,得到电缆两端接不同负载时,空间电磁场在电缆上产生的感应电流的解析表达式;分析了电缆感应电流的谐振机理,得到了谐振频率与电缆长度应满足的关系;并讨论了感应电流谐振与大地电导率、电缆架空高度等参数的关系。研究结果表明,当电缆感应电流发生谐振时,电缆–大地回路时间常数越大,感应电流越大;当大地电导率为0.01 S/m、照射波频率为75 MHz、电缆半径为4 mm、电缆距地高度为1 m、电缆长度为2 m、电缆两端架空时,电缆上感应电流的理论计算结果与实测结果之间的误差5 d B。     

装配式钢结构建筑热工性能测试研究

围护结构热工性能是影响建筑物节能效果的重要指标.通过测试东莞某装配式钢结构示范项目两种不同构造复合墙板的传热系数、隔热性能及外立面红外热像法热工缺陷,对比2种复合墙板热工性能的差异及墙板与钢质梁、型钢骨架之间节点构造对建筑物能耗的影响;分析两种复合墙板在夏热冬暖地区低能耗装配式钢结构建筑围护体系中的适用性.     

做好安全评价实现安全发展

安全评价反映了安全发展的本质及其要求,体现了安全生产“以人为本”和“预防为主”的理念,是从传统方式向现代管理方式科学发展的具体体现,是实现安全生产监管、监察“关口前移”的一个有效手段。成为安全生产重要的技术保障手段之一。     

直立锁边铝镁锰合金屋面施工技术

结合国家奥体中心体育馆改扩建工程,介绍直立锁边铝镁锰合金金属屋面设计构造、工程难点和屋面特点.并重点介绍屋面板的加工、垂直和水平运输、屋面系统的安装等施工工艺.结果表明,扩建后的金属屋面外观效果良好.     

S7-300 PLC与直流调速装置6RA70的通讯

本文介绍S7-300 PLC与直流调速装置6RA70用PROFIBUS DP协议通讯的基础。     

义马煤田自然发火事故统计分析及防治对策

通过对义马煤田近50年来矿井自然发火事故进行统计分析,总结出义马矿区煤层自然发火的一般规律,提出了有针对性的防治对策,对现场防灭火工作具有现实指导意义。     

烟气余热的回收利用

以某医疗制品有限公司的节能改造项目为例,结合原系统负荷及烟气余热参数,提出了利用排烟余热技术制冷制热的改造方案,改造项目的顺利实施,为企业带来了良好的经济效益和社会效益。     

油品检测技术的应用

介绍了设备油品检测技术和开展设备油品检测工作的基本方法及油品状态监测管理过程中的注意事项等.     

Accumulation of 2-Keto-L-Gulonate at 33℃ by a Thermotolerant Gluconobacter Oxydans Mutant Obtained by Ion Beam Implantation

To obtain thermotolerant mutants of G. oxydans, which can enhance the transformation rate of L-sorbose to 2-Keto-L-gulonate （2-KLG） at 33℃ in a two-step process of vitamin C manufacture, ion beam was used as a mutation source. Gluconobacter oxydans GO and Bacillus megaterium B0 were used in this study. The original strain Gluconobacter oxydans GO was mutated by the heavy ion implantation facility at the Institute of Plasma Physics, Chinese Academy of Sciences. Several mutants including Gluconobacter oxydans GI13 were isolated and cocultured with Bacillus megaterium B0 at 33℃ in shaking flasks. The average transformation rate of the new mixed strain GI13-B0 in per gram-molecule reached 94.4% after seven passages in shaking flasks, which was increased by 7% when compared with the original mixed strain G0-B0 （Gluconobacter oxydans GO and Bacillus megaterium B0）. Moreover, the transformation rate of I13B0 was stable at 94% at temperatures ranging from 25℃ to 33℃, which would be of much value in reducing energy consumption in the manufacture of L-ascorbic acid, especially in the season of summer. To clarify some mechanism of the mutation, the specific activities of L-sorbose dehydrogenase in both GO and GI13 were estimated.     

A Mutant of Bacillus Subtilis with High-Producing Surfactin by Ion Beam Implantation

In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological changes in the bacteria were observed by scanning electron microscope （SEM）. The optimum condition of ions implantation, 20 keV of energy and 2.6 × 10^15N^＋/cm^2 in dose, was determined. A mutant, B.s-E-8 was obtained, whose surface activity of 50-fold and 100-fold diluted cell-free Landy medium was as 5.6-fold and 17.4-fold as the wild strain. The microbial growth and biosurfactant production of both the mutant and the wild strain were compared. After purified by ultrafiltration and SOURCE 15PHE, the biosurfactant was determined to be a complex of surfactin family through analysis of electrospray ionization mass spectrum （ESI/MS） and there was an interesting finding that after the ion beam implantation the intensities of the components were different from the wild type strain.