共查询到20条相似文献,搜索用时 312 毫秒
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研究了利用GaAs作为衬底的HgCdTe MBE薄膜的表面缺陷,发现其中一类缺陷与Hg源中杂质有关。采用SEM对这类缺陷进行正面和横截面的观察,并采用EDX对其正面和横截面进行成分分析。并设计了两个实验:其一,在CdTe/GaAs衬底上,低温下用Hg源照射20min,再在其上继续高温生长CdTe;其二,在CdTe/GaAs衬底上,一直用Hg源照射下高温生长CdTe。两个实验后CdTe表面都出现与HgCdTe表面相比在形状和分布上类似的表面缺陷,采用光学显微镜和SEM对CdTe表面缺陷进行了观察,通过CdTe表面缺陷和HgCdTe表面缺陷的比较,我们证实了这类表面缺陷的成核起源于Hg源中杂质。 相似文献
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文章通过分析电子商务模式和移动Agent技术的特点,研究了不可靠环境下基于移动Agent协作式电子商务的安全性问题,论述了安全电子商务模式的技术特点和安全风险,并分析了主要的解决方案。应用结果表明,从不可靠主机环境和移动Agent本身两方面出发,综合使用多种安全技术措施可以较好地实现基于移动Agent的安全电子商务。 相似文献
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基于EDGE技术原理的分析,通过调研中国联通EDGE业务在现网中的覆盖情况,从业务启动条件、系统升级需求、覆盖区域设计、频率规划等方面详细介绍了网络建设中的典型问题。此外,还分析了业务启动后对网络的影响,最后进一步阐述了EDGE业务的开展建议。 相似文献
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在分析了P2P网络模式和数字版权管理(DRM)技术体系的基础上,提出了基于P2P模式的DRM系统体系,并对系统体系结构和传输协议进行了研究与探讨.基于体系的拓扑结构,提出了体系功能框架,并对其中内容管理、内容标识、付费机制和质量控制进行分析和设计.同时以数字内容的生命周期和价值链为依据,对体系工作的流程进行了深入探讨.给出了体系的数字内容上传和下载协议,实现了P2P网络模式与DRM技术体系的有效集成. 相似文献
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利用两步生长法在蓝宝石纳米图形衬底(NPSS)上生长得到高质量的氮化镓薄膜。通过XRD和SEM对薄膜质量的表征和研究发现,为得到高质量的氮化镓(GaN)薄膜,在NPSS上生长时得到的最优缓冲层厚度为15nm,而在微米级尺寸的图形衬底(MPSS)上得到的最优缓冲层厚度远大于15nm。同时,在NPSS上生长氮化镓薄膜的过程中观察到一个有趣的现象,即GaN在NPSS上生长的初始阶段,氮化镓晶粒主要在图形之间的平面区域生长,极少量的GaN在衬底图形的侧面上聚集生长。这一有趣的现象明显不同于GaN在MPSS上的生长过程。接着,又在NPSS上生长了GaN基LED结构,并对其光电性能进行了研究。 相似文献
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3G手机时代的来临给PCB的制造技术带来了巨大的挑战,文章介绍了3G手机对PCB行业的影响、PCB高密度化的要求、CCL高性能化的要求、PCB加工技术的要求。 相似文献
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单站无源定位技术具有隐蔽性强、设备量小及系统相对独立等优点,有着较强的实用价值.以往人们对运动单站无源定位技术研究较多,而对固定单站无源定位技术研究相对较少.针对此种情况,文章对固定单站对运动目标的无源定位技术的基本原理进行了分析,并提出了多普勒变化率、到达角变化率等定位参数的测量方法. 相似文献
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刘凡 《电信工程技术与标准化》2014,(8):21-26
桌面虚拟化技术的应用可简化管理,但需要正确规划才能消除存储设备的瓶颈,确保用户感受和满足增长需求。本文结合桌面虚拟化项目的部署经验,探讨桌面虚拟化部署过程中存储、备份的需求、面临的挑战及技术的选择和应用。 相似文献
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The distribution of Fc receptors on the surface of clinical isolates of streptococci was examined by immunoelectron microscopy. A unique two-layered ferritin tagging was observed on the surface of isolate MS-4 (group A). The spacing between the layers (10-40 nm) was narrower than that of the layered protein A (30-70 nm) on Staphylococcus aureus. Labeling on the other isolates, IP-28 (group A) and ES-21L (group C), showed similar rough layers, but the labeling were clearly different in thickness and density. The labeling on isolate IP-28 was also similar to that on strain AR1 (group A), reported previously, while the labeling on ES-21L was similar to that on protein G producing strain G148 (group G) in thickness. However, it was obviously thinner than that on IP-28 and AR1. These results strongly suggest that there are at least three distribution patterns of Fc receptors on streptococci, and these are distinct from that of protein A. 相似文献
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Mutual-information-based registration of medical images: a survey 总被引:78,自引:0,他引:78
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Ledoux P. Auge J. Boniort L.Y. Dupont P. Goudeau J. Saugrain J.M. Rousseau J.C. Mohanna Y. 《Lightwave Technology, Journal of》1989,7(8):1270-1274
The authors point out the formation mechanism of axial stress, describes the method and the apparatus used for measurements, and presents the results obtained during a study of loss reduction on trapezoidal core 1.55-μm dispersion-shifted fibers manufactured by the MCVD technique. It is concluded that the stress measurements on fiber are less accurate than those on preform (experimental dispersion reaches 15% instead of 5%). The various observations made from measurements on preform show that the axial stress is related to the index profile and that the core axial stress increases with the GeO2 content. The measurements performed on fiber show that the level of stress is linearly dependent on the drawing tension and that the stress profile is related to the glass-transition temperature of the different materials. Furthermore, this method of stress measurement is complementary to the more standard index profile measurement on fiber or on preform 相似文献
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An analytical technique to determine the effects of finite ground plane on the radiation characteristics of a microstrip antenna is presented. The induced currents on the ground plane and on the upper surface of the patch are determined from the discontinuity of the near field produced by the equivalent magnetic current source on the physical aperture of the patch. The radiated fields contributed by the induced current on the ground plane and the equivalent sources on the physical aperture yield the radiation pattern of the antenna. Radiation patterns of the circular patch with finite ground plane size are computed and compared with the experimental data, and the agreement is found to be good. The radiation pattern, directive gain and input impedance are found to vary widely with the ground plane size 相似文献
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M2M在3GPP SA2的研究进展 总被引:1,自引:0,他引:1
随着物联网的快速发展,M2M成为各个标准化组织研究和标准制定的工作重点。3GPP作为移动通信技术的主要研究和标准制定者,对M2M的相关研究和标准制定也在加紧进行。本文在介绍3GPP各个工作组的工作情况的基础上,重点介绍了M2M在3GPP在SA2的研究和标准化进展情况。 相似文献
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In this paper, recent literature on the discussion on high-speed backplanes with optical, electrical, and mixed solutions, as well as on polymer-waveguide systems suitable for implementation on printed circuit boards (PCBs), is reviewed from the point of view of their optical losses. The reevaluation of the optical power budget for realistic high-speed optical polymer-waveguide links on backplanes showed that signal amplification is necessary to boost the signal, which resulted in an additional literature review on advances in optical amplifiers based on silicon bench technology available. Finally, a concept study of an active optical waveguide amplifier device, based on planar optical waveguide amplifiers and semiconductor optical amplifiers, was performed. The amplification device can be flip-chip mounted on the backplane to compensate for optical losses due to signal routing, which increases the overall degree of freedom in waveguide routing on high-density interconnects for backplanes. The hybrid concept design guarantees compatibility with the processes of the PCB industry. 相似文献
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十九届五中全会审议通过的《中共中央关于制定国民经济和社会发展第十四个五年规划和二〇三五年远景目标的建议》(以下简称"《规划建议》"),描绘了未来5年乃至15年我国经济社会发展的宏伟蓝图,也给新型智慧城市建设谋定了新的方向。文章分析了《规划建议》对新型智慧城市建设的方向指引,剖析了新型智慧城市建设在贯彻落实《规划建议》方面的作用,并就加快推进新型智慧城市建设提出了有针对性的思考和建议。 相似文献
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Thomas S.G. Johnson E.S. Tracy C. Maniar P. Xiuling Li Roof B. Hartmann Q. Ahmari D.A. 《Electron Device Letters, IEEE》2005,26(7):438-440
In this letter, we report the first demonstration of InGaP/GaAs heterojunction bipolar transistors (HBTs) on germanium-on-insulator (GOI) substrates. We have performed physical characterization of the epitaxial layers to verify the high quality of the III-V epitaxial material grown on the GOI substrates and performed dc characterization of large-area InGaP/GaAs HBTs fabricated on the substrates. The InGaP/GaAs HBTs realized on GOI substrates were compared with identical devices grown on bulk germanium substrates and similar devices on semi-insulating GaAs substrates. 相似文献