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     

Diurnal thermal cycling effects on microwave signatures of thin seaice

To investigate effects of diurnal thermal cycles on C-band polarimetric backscatter and millimeter-wave emission from sea ice, the authors carried out a winter experiment at the outdoor geophysical research facility (GRF) in the cold regions research and engineering laboratory (CRREL), the ice sheet grew from open sea water to a thickness of 10 cm in 2.5 days, during which they took polarimetric backscatter data with a C-band scatterometer, interlaced with brightness temperature measurements at 90 GHz in conjunction with meteorological and sea ice characterizations. The initial ice growth in the late morning was slow due to high insolation. As the air temperature dropped during the night, the growth rate increased significantly. Air temperature changed drastically from about -12 to -36°C between day and night, the diurnal thermal cycle repeated itself the next day and the growth rate varied in the same manner. Ice temperature profiles clearly show the diurnal response in the ice sheet with a lag of 2.5 h behind the time of the maximum short-wave incident solar radiation. The diurnal cycles are also evident in the millimeter-wave brightness temperature data, measured sea ice backscatter revealed substantial diurnal variations up to 6 dB with repeatable cycles in synchronization with the temperature cycles and the brightness temperature modulations, the diurnal cycles in backscatter indicate that the dominant scattering mechanism related to thermodynamic processes in sea ice is reversible, a diurnal backscatter model based on sea ice electrodynamics and thermodynamics explains the observed diurnal signature. This work shows that diurnal effects are important for inversion algorithms to retrieve sea ice geophysical parameters from remote sensing data acquired with a satellite synthetic aperture radar (SAR) or scatterometer on Sun-synchronous orbits     

基于空间矩的灰度边缘亚像元度量精度分析

灰度图像中边缘定位受采样密度限制，亚像元精度度量方法在需要高精度的应用中受到重视，要想知识到底需要多高的分辨率才能达到定精度指标，就有必要分析特征定位方法的最坏情况的精度，文中用分析和实验的方法给出了基于空间矩的边缘定位方法，对于边缘点，边缘直线以及直边缘区域的最坏情况定位精度分析。分析和讨论的结果不但可以用来确定已知形状位置估计的最大误差，而且还可用于对准的形状几何参数，以获得较高的精度。     

Chopper stabilised ΠΔΣ analogue to digitalconversion

A chopper stabilised ΠΔΣ ADC architecture is proposed. A chopper stabilised version of ΠΔΣ ADC, which has identical performances to the regular ΠΔΣ ADC but is immune to low frequency noises such as DC offsets, can be obtained without adding hardware complexities     

二聚酸甲酯的合成研究

研究了以自制的脂肪酸甲酯为原料、几种不同催化剂催化合成二聚酸甲酯的反应。结果表明,用活性自土作催化剂,用量（质量分数）为脂肪酸甲酯的10％,反应温度240℃,反应时间6h的条件下,二聚酸甲酯的收率可达到39％。此工艺为二聚酸甲酯的合成提供了一条新的路线。     

Silicon thin films prepared in the transition region and their use in solar cells

Diphasic silicon films (nc-Si/a-Si:H) have been prepared by a new regime of plasma enhanced chemical vapour deposition in the region adjacent of phase transition from amorphous to microcrystalline state. Comparing to the conventional amorphous silicon (a-Si:H), the nc-Si/a-Si:H has higher photoconductivity (σ_ph), better stability, and a broader light spectral response range in the longer wavelength range. It can be found from Raman spectra that there is a notable improvement in the medium range order. The blue shift for the stretching mode and red shift for the wagging mode in the IR spectra also show the variation of the microstructure. By using this kind of film as intrinsic layer, a p–i–n junction solar cell was prepared with the initial efficiency of 8.51% and a stabilized efficiency of 8.01% (AM1.5, 100 mw/cm²) at room temperature.