Change of characteristics of desulfurization and denitrification by combustion flue gas composition and electrode configuration under pulsed corona discharge

Laboratory-scale and parametric experiments of SO₂ and NO_x removal from the simulated combustion gas by pulsed corona discharge have been performed by changing the combustion gas composition and temperature, the electrode configuration of plasma reactor, and the polarity of high-voltage electrode. The following results are obtained: 1) the higher the concentration of H₂O and O₂, the higher the efficiency of desulfurization and denitrification at the same specific input; 2) the pulsed corona discharge with a voltage pulsewidth as short as 200 ns of negative polarity shows the possibility to attain almost 90 percent deSO_x and deNO_x efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron-beam process; 3) the deNO_x characteristics show a little temperature dependence in the range of 70 to 130°C, but the deSO_x efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSO_x reaction; 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor whose composition is identified to be 49 mol% (NH₄)₂SO₄ and 47 mol% of 2NH₄NO₃ · (NH₄)₂SO₄, and the ratio of SO₂, NO and NH₃ of the deposit is almost equal to that of supplied gas.     

Study on characteristics of Ni-W-B composites containing CeO2 nano-particles prepared by pulse electrodeposition

Ni-W-B composites containing CeO2 nano-particles on the surface of 45 steel were prepared by pulse electrodeposition,and the in-fluence of pulse frequency,pulse duty circle and heat treatment temperature on the structures and properties were investigated.The results in-dicated that the pulse co-deposition of Ni,W,B and CeO2 nano-particles led to Ni-W-B/CeO2 composites possessing higher microhardness and better wear resistance when heat-treated at 400 oC for 1 h.The microhardness of 636 HV and the deposition rate of 0.0281 mm/h of the as-deposited alloy were the highest at pulse frequency of 1000 Hz,pulse duty circle of 10% and pulse average current density of 10 A/dm2.The composites were mainly in the amorphous state and were partially crystallized as-deposited,and the crystallization trend was strength-ened when heat-treated at 400 oC.Decreasing pulse duty cycle from 75% to 10% was favorable to the refinement in grain structures and im-provement of microstructures.The crystal sizes of the composites were smaller by means of pulse electrodeposition.     

逆变器脉宽调制中基于脉冲的死区补偿方法

逆变器PWM波形中由于死区时间的存在可能会导致电力电子器件的短路,最终影响输出波形并降低可靠性.虽然每一个死区时间都很短.但如果按周期计算的话,叠加起来的死区会对输出的PWM波形产生很大影响.提出了一种修正死区时间的方法,即基于脉冲的死区补偿方法(PBDTC).与其他方法相比,该方法需要的硬件和软件比较少,且成奉较低.该方法在分析单个脉冲死区时间的基础上,对每个单脉冲进行修正.将实验结果与其他方法进行了比较.证明该补偿方法较为完美.     

基于AT89C2051的晶闸管触发电路设计

介绍了一种基于AT89C2051单片机为核心的晶闸管触发电路,并详细阐述了其软硬件结构,具有高集成度、智能化、体积小、安全、迅速、可靠稳定等优点,今后必将被广泛应用。     

负色散镜的设计、制备及在掺钛蓝宝石激光谐振腔内的使用

根据钛宝石激光器的要求设计了性能优良的两种负色散镜(NDM1和NDM2)。NDM1同时引入啁啾效应和G-T效应产生大的群延迟色散量以减少光在负色散镜上的反射次数。NDM2仅引入G-T效应产生较小的群延迟色散以补偿腔内自相位调制带来的部分啁啾。选用离子束溅射法制备了这两种负色散镜。用分光光度计测试了它们的透射率。结果表明,所制备的负色散镜的性能与设计性能非常接近。使用这两种负色散镜进行掺钛蓝宝石激光谐振腔内色散补偿实现了飞秒脉冲锁模,获得了15 fs的超短脉冲。     

脉冲电流在改善金属凝固组织中的作用

综述了脉冲电流在改善金属凝固组织方面的研究现状。从理论上归纳和分析了脉冲电流在金属凝固过程中产生作用的主要机制。     

不拆高压引线测量耦合电容器介质损耗和电容量

针对耦合电容器拆高压引线传统预防性试验的不足,根据不拆高压引线测量耦合电容器介质损耗和电容量值的试验方法,通过对南雁变南仙4367线等4条线路实测,与传统试验数据进行了对比分析,证明该方法可行有效。     

超超临界1000MW机组凝结水泵及高压变频器的计算与选型

为了降低发电厂的厂用电率,实现节能减排,大容量电机的变频运行是首选措施之一。介绍了超超临界1 000 MW发电机组配置的凝结水泵及其高压变频器和相关配套设备的计算与选型,提出了高压变频器选型中应注意的问题。     

F-TRIA01: A Fast Bipolar Transimpedance Amplifier

This paper describes a new transimpedance amplifier for fast current pulses delivered by high energy particle detectors. The choice of a bipolar technology allowed a 100 low input impedance and a rise time down to 1 nS. The fully differential current mode architecture provides an excellent linearity and a large versatility as for its transimpedance, bandwidth and power consumption.