GaN基激光器的研究进展

GaN材料作为第三代半导体材料具有十分独特的性能,其发光波段可以覆盖从红外到深紫外波段。GaN材料击穿电场强、发光效率高,使其在显示、照明、通信等领域具有非常广泛的应用。综述了GaN基激光器的发展历程及其失效和退化机制的研究进展。目前最新的蓝光GaN基激光器在3 A电流连续工作时的电压和输出功率为4.03 V和5.25 W;最新的绿光激光器波长为532 nm,在电流1.6 A时,输出功率为1.19 W。进一步阐述了GaN基激光器退化的主要表现,即随着工作时间的延长,激光器发光效率降低、光转化效率降低以及电压升高。总结了四种主要的退化模式,分别为封装退化、静电损伤、腔面退化和芯片失效。     

量子阱结构对GaN基紫光二极管性能的影响

采用不同MQW结构在MOCVD系统上生长UV-LED外延片.对样品进行了X射线衍射、电注入发光(EL)和光致发光谱(PL)测试,通过优化LED器件材料的生长条件,获得了光发光特性一般而电发光特性优良的高质量多量子阱紫光LED外延片.     

电场作用下熔铁与铝碳质水口耐材间的润湿和侵蚀行为

摘要：探究了外加电场作用下铁熔体与水口组成材料间的润湿和侵蚀行为。通过高温电润湿实验可知,在铁熔体和水口组成材料基板间施加电场,促进了铁熔滴与固体基板间的润湿,且在一定电场强度范围内,固 液相间的接触角随着电场强度的增加而减小,固 液相间的润湿性变好。对电润湿后两相界面的微观结构进行了分析,结果表明外加电场促进了铁熔体与水口组成材料间的原子迁移,显著改善固液两相界面间的传质、扩散和溶解等作用。电润湿反应过程中铝碳水口表面经脱碳后产生了孔隙,并且在外加电场作用下铁熔体易于向水口基板内部渗透,导致铁熔体对铝碳水口的侵蚀程度较高纯石墨和氧化铝基板更为严重。     

中国输电塔钢结构现状及市场情况

目前国内外输送电力的主要方法之一就是采用架空线路,中国大陆从1879年点燃了第一盏电灯,就开始了输电线路建设.输电塔是输电线路的一个重要部分,其作用是支承空中的导、地线.输电塔在我国经历了几次大的发展,从早期最原始的用木材为主作为输电杆塔,到后来用钢筋水泥杆为主作为输电杆塔,新中国成立后,开始建设220kV、330kV、500kV输电线路工程,才开始大量使用钢材作为输电塔的主要材料.尤其是目前我国正在加强电网建设、推进全国联网和正在准备进行电网特高压升级,将建设1000kV交流特高压输电线路、±800KV直流特高压输电线路,对钢材将有巨大的需求,对钢材品种和规格有更广的要求.     

电致塑性效应及其工程应用

电致塑性效应是材料在电的作用(包括电子照射、电场、电流脉冲等电刺激)下,变形抗力降低、塑性增加的一种现象.从电子对位错作用机制、磁场模型和磁学性能、物质波假说、不同层次结构的演变几个方面综述了电致塑性效应机理研究.以线材拔制和板带轧制为主介绍了电致塑性效应在很多领域的应用研究和良好的效果.对电致塑性技术的应用前景和需进一步研究的问题进行了分析,为其在钢铁业的工程应用提供了介绍和借鉴.     

辊芯表层电渣加热渣池热电场及影响因素的数学模拟

在建立辊芯表层电渣加热物理模型和数学模型的基础上,利用大型有限元软件ANSYS对辊芯表层加热系统中渣池热电场及影响因素进行了模拟研究。研究结果表明,在辊芯表层和电极之间存在一个强电流区,使辊芯表层被快速加热;随着电压的升高、渣池深度的增加和电极与辊芯间距的减小,渣池中的电场强度和整体温度升高,高温区集中在辊芯与电极之间;电极数量越多,系统的电场分布越均匀。     

高密度电法在岩溶勘察中的应用

近几年来,国家大力发展电网工程,各种规模的电压等级都有,很多输电线路都通过灰岩分布区,灰岩分布区易发生地面塌陷等地质灾害,物探和钻探相结合是岩溶勘察中的重要手段。高密度电法兼具电阻率剖面法与测深法的功能,其数据采集密度大、精度高的断面测量结果能较直观地反映地层及电性异常体的形态及纵、横向展布情况。本文介绍了高密度电法的原理与野外工作方法,通过应用实例说明高密度电法在输电线路中岩溶勘察中的作用。     

GaN:Eu,Dy薄膜的结构和发光特性研究

通过离子注入方法制备了一系列稀土Eu和Dy掺杂的GaN薄膜，研究了其结构、发光特性和能量传递机制。拉曼(Raman)光谱和X射线衍射(XRD)的研究一致表明：当Eu剂量保持不变时，随着Dy剂量增加，GaN晶格应变出现了先张应变后压应变的变化趋势。阴极荧光(CL)光谱表明：Eu,Dy共掺GaN样品的发光峰和单掺GaN样品的发光峰基本一致，这说明Eu和Dy共掺时并没有显著改变彼此的局域晶体场环境。在GaN中，对于Eu离子，⁵D₀→⁷F₂跃迁所对应的625 nm发光最强；对于Dy离子，⁴F_9/2→⁶H_13/2对应的583 nm发光最强。在Eu离子剂量保持不变的情况下，随着Dy离子注入剂量的增加，583 nm的发光逐渐变强，而625 nm的发光变弱。进一步，结合计算分析表明Eu离子主要通过电偶极-电偶极共振方式传递能量给Dy离子。最后发现随着离子注入剂量的改变，发光颜色在白色和红色间变化，色温在3889～4839 K变化...     

物探方法在德兴银山矿田勘探中的试验应用

江西德兴银山矿床是一个Cu-Pb-Zn-Au-Ag矿化集中区,该处地质工作程度较高,但物探资料较缺乏。作者采用双频激电法、自然电场法和天然电场选频法开展试验探测工作,期望探讨方法的有效性,为矿区深、边的找矿工作提供科学依据。根据探测结果可知,银山矿区的铅锌矿和斑岩铜矿具有十分明显的低阻高极化特性,激电方法适合于该矿区的边部找矿工作,但矿区工业电流干扰大,所以最好采用大功率激电方法;自然电场和天然电场选频法方法简便,仪器轻便,其异常与矿体或构造具有较好的对应性,特别是自然电场法适合于井下巷道中开展工作,可作为今后深部矿产预测的方法之一。     

收尘用高压电源的比较分析与优化设计

为使电场强度满足工况要求,粉尘荷电效果理想,本文在分析不同高压电源技术特性的基础上,设计了由四个电场组成的静电收尘设备,并根据高压电源的使用工况进行了优化设计,其中,第一个电场由高频高压脉冲电源供电,其余电场由适合高比电阻的恒流源供电。设备投运后,工作状况良好,证明本文的相关分析符合实际情况,设计满足使用要求。     

改进增强颗粒加入方式对喷射共沉积6066Al/SiCp组织性能的影响

应用喷射共沉积技术制备了 6 0 6 6 Al/Si Cp复合材料 ,用金相和扫描电镜观察显微组织 ,测试了材料的力学性　　能 ,并研究了增强颗粒加入方式对材料组织均匀性及力学性能的影响     

Neurotic disturbances, depression and anxiety disorders in the population living in the vicinity of overhead high-voltage transmission line 400 kV. Epidemiological pilot study

Numerous reports suggest a relationship between the increased incidence of depressive and neurotic symptoms in humans and the exposure to extremely low frequency electromagnetic field (EMF) at the place of residence. Our study was conducted in one of the Cracow suburbs with low socio-economic status, adjacent to an easement containing two 400 kV high-voltage transmission lines (distance up to 50 m from the line). The population investigated comprised 70 persons (35 males and 35 females). This group was exposed to EMF from 1986. A control group (n = 37), non-exposed to EMF, was also tested. The EMF intensity was measured by special devices. The following assessments instruments were used: Anamnestic Data Questionnaire, Neurotic Symptoms Questionnaire "O" Spielberger Self-Rating Questionnaire, and Beck-Self-Rating Scale. The measurements of the electric field levels taken at the front walls of investigated buildings averaged much higher than normal values of safety exposure. Our investigation showed the increased psychopathological values in all clinical tests. The difference between the group exposed to EMF and the control population was statistically significant. The results of our study did not support a possible cause-and-effect relationship between EMF and psychopathology observed. Some other factors (noise) can be responsible for the data obtained. The hypothesis that EMF produced by external electric power lines may enhance the occurrence of neurotic symptoms and depression, requires further clinical and experimental investigations.     

NOM Accumulation at NF Membrane Surface: Impact of Chemistry and Shear

The effects of solution chemistry, surface shear, and composition of natural organic matter (NOM) were investigated for their impact on accumulation of foulant material at the surface of charged polymeric nanofiltration membranes. The source of NOM was the Suwannee River. A bench-scale, batch recycle system was used with 20 hollow fiber, nanofiltration membranes. Membrane flux decline and foulant accumulation increased at low pH and high ionic strength as a result of neutralization of charge, electric double layer compression, and the apparent shift in conformation of charged NOM macromolecules. The rate of NOM accumulation decreased with operating time, suggestive of an eventual steady state between adsorption and desorption. The effect of NOM composition on membrane fouling could not be discerned by a standard technique to isolate hydrophobic and hydrophilic NOM fractions, quite possibly because of the fractionation methodology's failure to recover a small but important fouling fraction or because of NOM interactions that are lost when individual fractions are separately tested. However, a greater percentage of the hydrophilic than hydrophobic fraction permeated the membrane, in agreement with prior observations by others. Increasing the cross flow velocity from 85 to 255 cm∕s reduced the extent of flux decline, presumably due to hydrodynamic disruption of cake layer formation.     

Fields and currents in the organs of the human body when exposed to power lines and VLF transmitters

A study is made of the electric fields and currents induced in the organs of the human body when exposed to high-voltage 50-60-Hz transmission lines and 10-30-kHz high-power transmitters. Relevant analyses previously carried out are summarized and supplemented with detailed investigations that complete the picture. Incomplete, misleading, and incorrect statements and methods in the related literature are pointed out, completed, and corrected. The major contribution is to provide quantitatively accurate, relatively simple analytic formulas that relate the incident electric field to the induced field in the organs of the body. The formulation and solution of the underlying integral equation are carried out in the Appendix.     

Effect of environment and grain size on cyclic deformation and surface hardening of iron

Specimens of commercially pure vacuum-melted iron with different grain sizes (0.02 to 0.9 mm diameters) were subjected to push-pull cyclic loading under plastic strain control at an amplitude of 5 × 10^-4 in both ultrahigh vacuum (UHV) and oxygen to investigate the effects of grain size and environment on cyclic surface deformation and microcrack initiation. The cyclic stress response curve is not affected by the environment. Fatigue in UHV produces diffuse, wavy but discrete slip lines in which tiny microcracks are initiated. In the presence of oxygen, fatigue produces prominent slip bands along which intense slip band cracks develop. Slip lines developed in UHV, although weaker in intensity, cover more surface area than those developed in oxygen. With increasing grain size, initiation of fatigue cracks along grain boundaries becomes more important. Surface hardening of the specimens and the depth of the surface hardened layer were examined by microhardness measurements after cyclic deformation. In both environments, the surface layer shows an enhanced microhardness over that in the bulk, and the depth of the hardened surface layer increases with grain size. The depth profile of microhardness is not significantly affected by the environment. formerly Graduate Research Assistant at Northwestern Uni-versity,     

UFC 工艺加压泵电气传动装置的选型策略

针对韶钢超快冷项目改造中加压泵电气传动装置的选型,本文通过对超快冷加压泵电气传动系统的分析和计算,并结合现场的实际使用情况,摒弃了采用变频电动机加合资品牌串联多重化高压变频器的加压供水泵传动方式,选用了满足工艺要求且无需定制的普通高压电动机加单元串联多重化变频器的低成本选型方案。通过韶钢3450mm生产线实际验证,该方案完全满足超快冷工艺现场使用要求,系统运行稳定,为韶钢3450mm超快冷改造项目直接节约投资150多万元。     

短流程电炉原料工程刍议

文中论述了重视开发电炉新原料，金属化球团，脱炭粒铁并促其快速发展，使入炉原料有一个合理比例，以保证电炉钢铁质量。     

高压直流干扰大幅值管地电位产生原因及影响因素分析

基于实际的工程参数建立了高压直流干扰电场计算模型,利用数值模拟计算技术对高压直流干扰大幅值管地电位的产生原因进行探究。考察接地极与管道之间的间距、管道防腐层类型、管道长度及土壤结构等因素对高压直流干扰下管地电位的影响规律,得到高压直流干扰大幅值管地电位是在接地极与管道距离较近、防腐层的绝缘性能较高、管道长度较大及上低下高的土壤电阻率分层结构共同作用下产生的。      

高压变频器在120t转炉除尘风机上的应用

介绍了高压变频器在120t转炉一次除尘、KR、精炼和辅原料除尘风机上的应用,其节电效果显著。     

Electromagnetic Environmental Impact of 500-kV Double-Circuit Transmission Lines

The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law,and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence,the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line,the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase.Finally,the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.