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991.
谈谈"内网"安全 总被引:6,自引:1,他引:6
杜虹 《信息安全与通信保密》2005,(1):81
内网即Intranet,是相对于外网Extranet而言的。广义的讲,是所有党政机关、企事业单位的内部网络都称为内网。狭义的讲,对于我国电子政务建设,中办发【2002】17号文件中电子政务内网的定义为:主要是副省级以上政务部门的办公网,与副省级以下政务部门的办公网物理隔离,也与政务外网和互联网物理隔离。下面就广义的内网谈谈安全问题。一、物理隔离与逻辑隔离电子政务内网是涉及国家秘密的信息系统,按照国家保密部门有关规定,不能与互联网进行直接的或间接的连接。电子政务外网与互联网是逻辑连接的,因此电子政务内网也要求与电子政务外网物理… 相似文献
992.
Wireless Networks - The increasing demand for real-time applications of Wireless Sensor Networks (WSNs) makes Quality of Service (QoS)-based charging scheduling models an interesting and hot... 相似文献
993.
994.
Yogesh Sharma Radhe Agarwal Liam Collins Qiang Zheng Anton V. Ievlev Raphael P. Hermann Valentino R. Cooper Santosh KC Ilia N. Ivanov Ram S. Katiyar Sergei V. Kalinin Ho Nyung Lee Seungbum Hong Thomas Z. Ward 《Advanced functional materials》2020,30(3)
Multiferroic materials have driven significant research interest due to their promising technological potential. Developing new room‐temperature multiferroics and understanding their fundamental properties are important to reveal unanticipated physical phenomena and potential applications. Here, a new room temperature multiferroic nanocomposite comprised of an ordered ferrimagnetic spinel α‐LiFe5O8 (LFO) and a ferroelectric perovskite BiFeO3 (BFO) is presented. It is observed that lithium (Li)‐doping in BFO favors the formation of LFO spinel as a secondary phase during the synthesis of LixBi1?xFeO3 ceramics. Multimodal functional and chemical imaging methods are used to map the relationship between doping‐induced phase separation and local ferroic properties in both the BFO‐LFO composite ceramics and self‐assembled nanocomposite thin films. The energetics of phase separation in Li doped BFO and the formation of BFO‐LFO composites are supported by first principles calculations. These findings shed light on Li's role in the formation of a functionally important room temperature multiferroic and open a new approach in the synthesis of light element doped nanocomposites for future energy, sensing, and memory applications. 相似文献
995.
In‐Hwan Ahn Seon Ju Yeo Kinam Jung Gumin Kang Dong‐Hun Shin Ho Seong Jang Byunghoon Kim Minwoo Nam Seok Joon Kwon Doo‐Hyun Ko 《Advanced functional materials》2020,30(13)
Upconversion nanoparticles (UCNPs) have been integrated with photonic platforms to overcome the intrinsically low quantum efficiency limit of upconversion luminescence (UCL). However, platforms based on thin films lack transferability and flexibility, which hinders their broader and more practical application. A plasmonic structure is developed that works as a multi‐functional platform for flexible, transparent, and washable near‐infrared (NIR)‐to‐visible UCL films with ultra‐strong UCL intensity. The platform consists of dielectric microbeads decorated with plasmonic metal nanoparticles on an insulator/metal substrate. Distinct improvements in NIR confinement, visible light extraction, and boosted plasmonic effects for upconversion are observed. With weak NIR excitation, the UCL intensity is higher by three orders of magnitude relative to the reference platform. When the microbeads are organized in a square lattice array, the functionality of the platform can be expanded to wearable and washable UCL films. The platform can be transferred to transparent, flexible, and foldable films and still emit strong UCL with a wide viewing angle. 相似文献
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997.
超宽带系统需要超宽带滤波器的相对带宽达到110%,并且使用常见的材料设计它,使其结构紧凑、价格便宜。该文将介绍用左右手传输线结构设计的新型超宽带滤波器。另外,利用微带线和共面波导相结合的方式来简化设计、缩小尺寸。其仿真结果证明了利用复合材料可产生负介电常数和负磁导率,滤波器在通带3.8到10.6GHz内的插入损耗小于1.0db。并且其中心频带附近的群时延约为0.20ns,这个群时延足够小,以至于它可以应用到无线通信系统中。 相似文献
998.
为了提高TD-SCDMA系统的传输速率,向国际电联IMT-Advanced所提技术指标迈进,TD-SCDMA的演进策略提上了研究议程。鉴于TD—SCDMA的短期演进HSPA(包括HSDPA和HSUPA)无法满足IMT-Advanced的要求,提出了HSPA+和LTE的概念。本文首先介绍了TD-SCDMA未来演进和发展的趋势,包括TD-SCDMA的增强、短期演进、中长期演进以及基于IMT-Advanced的4G等。然后重点分析了HSPA+的关键技术和协议架构等,最后对LTE的帧结构和多址方式进行了分析,提出了演进时的关键点和对策。 相似文献
999.
Tadao Tanabe Yuichi Kozawa Ken Suto Jun-ichi Nishizawa Ytaka Oyama 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(6):881-892
Stimulated Raman gain (SRG) spectroscopy using infrared pump pulses with narrow linewidth and a low-noise cw probe infrared laser was proposed. High-resolution Raman spectra of solutions were obtained. The SRG spectra of crystal GaP, benzene, and toluene were measured to confirm the spectral resolution and sensitivity over the terahertz (THz) region. We discuss the polarization dependence of the spectral measurement of carbon tetrachloride. Our system can detect organic molecules in aqueous solutions. 相似文献
1000.
Qian-Zhong Xue Shi-Chang Zhang Pu-Kun Liu 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(10):1407-1415
A design procedure for the H10□ to H01° sector-type mode converter at Ka-band is described in detail. As an example, an H10□ to H01° sector-type mode converter with an input rectangular port size as 7.112×3.556 mm2 and another output circular port diameter as 17.2 mm is designed and measured for insertion losses and wanted mode pattern. The mode converting efficiency from H10□ mode to H01° mode is about 91.2%. The insertion losses of the converter are lower than 0.1525 dB with 2GHz band. 相似文献