Pulse propagation in superconducting coplanar striplines

The phenomenological loss equivalence method (PEM), the enhanced two-fluid model for thin-film superconducting materials, and the dynamical calculation of radiation losses in planar structures are used-in the context of a linear filter approach-to model attenuation and dispersion of ultrafast pulses in coplanar striplines. The numerical simulation of this modeling shows excellent agreement with experimental results available in the literature. Simple relationships between the peak attenuation and delay time of the propagation pulse, and penetration depth at absolute zero and conductivity at critical temperature may open the possibility of using pulse distortion to characterize thin-film, high-temperature superconducting materials     

稳频激光陀螺中闭锁阈值的变化

本文由腔反射镜反向散射标量理论与模耦合理论讨论激光陀螺在稳频时闭锁阈值、反向散射系数幅值及其位相与腔结构的关系,给出了相应的实验结果。     

Traffic impacts of international roaming on mobile and personal communications with distributed data management

In this paper, we propose four network interconnection scenarios and the related signaling aspects for the international roaming traffic in mobile and personal communications. With or without international gateway relay nodes summarized from the proposed scenarios, we also derive three international roaming network sets {IR₁, IR₂, IR₃} for the observed signaling traffic model with twolevel databases. Based on the proposed performance metrics, analysis results show that under some reasonable assumptions the signaling traffic of international roaming is significantly impacted by the related gateway relay nodes and databases. In addition, the studied cache data management strategy at VLR can reduce the impacts of the signaling traffic of query operation, but the caching approach cannot improve the performance of update operation. Furthermore, the performance of proposed standalone STP scenario is better than that of integrated STP scenario for the international network connection.     

高速钢激光重熔后的组织与性能

研究了W18Cr4V高速钢激光重熔后的组织与性能。结果表明，常规淬回火组织经激光重熔后其硬度、韧性都有提高，熔化层的残余应力为技应力；经640℃回火后；由于残余应力的消除及重熔组织中马氏体的二次硬化和残余奥氏体的二次淬火效应其耐磨性能有了进一步地提高。     

山东水泥厂有限公司高温风机变频改造

本文综述了高压变频器在水泥厂高温风机上的应用情况，对改造过程、改造前后的耗电情况进行了对比，结果表明交流变频调速器，以适用性强、可靠必体育馆、操作方便等优势，受到用户的好评。     

基于认知的LTE系统动态频谱分配

传统的软频率复用(SFR)无法适应长期演进(LTE)系统中业务的动态分布,可能导致小区中心和边缘区域频谱利用率不均。针对此问题,该文提出一种基于认知的LTE系统动态频谱分配方法(Cog-DSA)。该方法利用基站间的相互协作获得频谱使用状态信息,从而确定可用频谱集合,并评估来自邻小区的同频干扰,最终根据可用资源块的通信质量,对重负荷小区边缘进行频谱的动态借用和服务基站的灵活选择。仿真结果表明,所提方法能够有效改善频谱利用率,减少小区间干扰,显著提升边缘用户的传输速率。     

RF-MBE生长的AlGaN/GaN高电子迁移率晶体管特性

用射频分子束外延技术研制出了室温迁移率为1035cm2/(V·s),二维电子气浓度为1.0×1013cm-2,77K迁移率为2653cm2/(V·s),二维电子气浓度为9.6×1012cm-2的AlGaN/GaN高电子迁移率晶体管材料.用此材料研制的器件(栅长为1μm,栅宽为80μm,源-漏间距为4μm)的室温非本征跨导为186mS/mm,最大漏极饱和电流密度为925mA/mm,特征频率为18.8GHz.     

RF-MBE生长的AlGaN/GaN高电子迁移率晶体管特性

用射频分子束外延技术研制出了室温迁移率为10 35 cm2 /(V·s) ,二维电子气浓度为1.0×10 1 3cm- 2 ,77K迁移率为2 6 5 3cm2 /(V·s) ,二维电子气浓度为9.6×10 1 2 cm- 2 的Al Ga N/Ga N高电子迁移率晶体管材料.用此材料研制的器件(栅长为1μm,栅宽为80μm,源-漏间距为4μm )的室温非本征跨导为186 m S/m m,最大漏极饱和电流密度为92 5 m A/m m,特征频率为18.8GHz.     

Si基MOCVD生长AlN深陷阱中心研究

通过PL 谱和Raman谱对MOCVD生长Si基Al N的深陷阱中心进行了研究,发现三个深能级Et1 ,Et2 ,Et3,分别在Ev 上2 .6 1,3.10 ,2 .11e V.Et1 是由氧杂质和氮空位(或Al间隙原子)能级峰位靠近重合共同引起的,Et2 、Et3都是由于衬底Si原子扩散到Al N引起的.在Si浓度较低时,Si主要以取代Al原子的方式存在,产生深陷阱中心Et2 .Si浓度高于某个临界浓度时,部分Si原子以取代N原子位置的方式存在,形成深陷阱中心Et3.实验还表明,即使经高温长时间退火,Al N中Et1 和Et2 两个深陷阱中心也是稳定的