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981.
作为2008年奥运会的举办城市,北京将会成为国内外游客主要聚集的地区,为了向用户提供"随时随地、方便快捷"的信息查询和位置查询服务,中国网通集团研究院开发了奥运"城市通"系统,通过该系统,用户可以使用一个具有定位功能的小灵通终端进行餐饮、娱乐、观光的出行导航和综合城市信息、企业信息的查询,因此,定位技术是实现"城市通"业务的核心,为开发其他增值业务提供了基础,本文将详细介绍定位技术在"城市通"业务中的应用。 相似文献
982.
983.
介绍了一种适用于三维毫米波集成电路的Si基微机械垂直过渡,该垂直过渡是两层0.1mm厚的共面波导传输线通过0.3mm厚中间层,在中间层采用了同轴结构,该同轴结构通过金属化通孔来实现。这一设计原理简单,结构简洁,便于优化设计,具有很宽的带宽和平坦的幅度响应。运用三维电磁场仿真软件对该垂直过渡结构进行了建模,并作了优化设计与仿真计算,运用微机械金属化通孔工艺和多层键合工艺研制了样品。在片测试结果表明该样品性能良好,在26.5~34.0GHz该过渡插入损耗小于3.5dB,带内起伏小于2dB。 相似文献
984.
985.
986.
本文针对带钢生产中“带钢尾端不好确认,打捆定位不准确”的瓶颈问题,首创性地运用计算机视觉检测技术,提出了一种新的带钢尾端自动定位控制系统。本系统由彩色摄像机、图像采集卡、PC机、PLC(可编程控制器)和执行机构组成。文中阐述了图像处理技术、PC机与PLC之间的通讯、PLC实现定位控制等关键问题。实践证明,系统使用后大大提了高定位的准确性和高效性,具有推广价值。 相似文献
987.
Cong Zhang Xin Liang Ruinian Xu Chengna Dai Bin Wu Gangqiang Yu Biaohua Chen Xiaolei Wang Ning Liu 《Advanced functional materials》2021,31(14):2008298
Surface segregation constitutes an efficient approach to enhance the alkaline hydrogen evolution reaction (HER) activity of bimetallic PtxNiy nanoalloys. Herein, a new strategy is proposed by utilizing the small gas molecule of H2 as the structure directing agent (SDA) to in situ induce Pt surface segregations over a series of PtNi5-n samples with extremely low Pt doping (Pt/Ni = 0.2). Impressively, the sample of PtNi5-0.3 synthesized under 0.3 MPa H2 delivers an extremely low overpotential of 26.8 mV (−10 mA cm−2) and Tafel slope of 19.2 mV dec−1, which is superior to most of the previously reported PtxNiy electrocatalysts. This is substantially related to the strong H2 in situ inducing effect to generate Pt-rich@Ni-rich core-shell nanostructure of PtNi5-0.3 with an ultrahigh Pt surface content of 46%. The specific mechanistic effects of H2 during the PtNi5-n synthesis process are well illustrated based on the combined experimental and theoretical studies. The density functional theory mechanism simulations further unravel that the evolved active site of PtNi5-n can efficiently reduce the reaction Gibbs free energies; especially for the scenario of PtNi5-0.3, the downward-shifted d band center of the Pt active site significantly reduces the Pt H bond strength, eventually resulting in the lowest absolute value of ΔGH. 相似文献
988.
Zheng Lv Zhongwei Man Hongtu Cui Zhenzhen Xu Huanhuan Cao Shuai Li Qing Liao Qihua He Lemin Zheng Hongbing Fu 《Advanced functional materials》2021,31(10):2009329
Lysosomes and mitochondria play an important role in maintaining cell homeostasis. Visualizing the long-term activities of lysosomes and mitochondria on the nanometer scale in live cells is essential for further understanding their functions but remains challenging due to the limitations of existing fluorescent probes, such as aggregation-caused quenching (ACQ) effect, limited signal-to-noise ratio from fluorescence “always on” in the process of targeting organelle and poor photobleaching resistance. Herein, two efficient red-emitting aggregation-induced emission (AIE) luminogens are reported, which showed “off-on” fluorescence characteristic and specific lysosomes as well as mitochondria targeting capability. Owing to their AIE characteristics, a Stokes’ shift larger than 100 nm, good biocompatibility, and excellent photostability, the AIE luminogens have been successfully utilized for high fidelity imaging of lysosomes and mitochondria. By virtue of these two probes, stimulated emission depletion (STED) images of dynamic lysosomal fusion and mitochondrial fission with a high resolution of 65.6 nm are obtained. Furthermore, the interactions between lysosomes and mitochondria in the process of mitophagy are recorded. This study also provides practical guidance for designing specific organelle targeting probes to support live cell dynamic super-resolution imaging. 相似文献
989.
Zijie Dai Manukumara Manjappa Yunkun Yang Thomas Cai Wei Tan Bo Qiang Song Han Liang Jie Wong Faxian Xiu Weiwei Liu Ranjan Singh 《Advanced functional materials》2021,31(17):2011011
The Dirac semimetal cadmium arsenide (Cd3As2), a 3D electronic analog of graphene, has sparked renewed research interests for its novel topological phases and excellent optoelectronic properties. The gapless nature of its 3D electronic band facilitates strong optical nonlinearity and supports Dirac plasmons that are of particular interest to realize high-performance electronic and photonic devices at terahertz (1 THz = 4.1 meV) frequencies, where the performance of most dynamic materials are limited by the tradeoff between power-efficiency and switching speed. Here, all-optical, low-power, ultrafast broadband modulation of terahertz waves using an ultrathin film (100 nm, λ/3000) of Cd3As2 are experimentally demonstrated through active tailoring of the photoconductivity. The measurements reveal the photosensitive metallic behavior of Cd3As2 with high terahertz electron mobility of 7200 cm2 (Vs)−1. In addition, optical fluence dependent ultrafast charge carrier relaxation (15.5 ps), terahertz mobility, and long momentum scattering time (157 fs) comparable to superconductors that invoke kinetic inductance at terahertz frequencies are demonstrated. These remarkable properties of 3D Dirac topological semimetal envision a new class of power-efficient, high speed, compact, tunable electronic, and photonic devices. 相似文献
990.
Aditya Mishra Masoud Alahbakhshi Ross Haroldson Qing Gu Anvar A. Zakhidov Jason D. Slinker 《Advanced functional materials》2021,31(31):2102006
Blue electroluminescence is highly desired for emerging light-emitting devices for display applications and optoelectronics in general. However, saturated, efficient, and stable blue emission has been challenging to achieve, particularly in mixed-halide perovskites, where intrinsic ion motion and halide segregation compromises spectral purity. Here, CsPbBr3−xClx perovskites, polyelectrolytes, and a salt additive are leveraged to demonstrate pure blue emission from single-layer light-emitting electrochemical cells (LECs). The electrolytes transport the ions from salt additives, enhancing charge injection and stabilizing the inherent perovskite emissive lattice for highly pure and sustained blue emission. Substituting Cl into CsPbBr3 tunes the perovskite luminescence from green through blue. Sky blue and saturated blue devices produce International Commission on Illumination coordinates of (0.105, 0.129) and (0.136, 0.068), respectively, with the latter meeting the US National Television Committee standard for the blue primary. Likewise, maximum luminances of 2900 and 1000 cd m−2, external quantum efficiencies (EQEs) of 4.3% and 3.9%, and luminance half-lives of 5.7 and 4.9 h are obtained for sky blue and saturated blue devices, respectively. Polymer and LiPF6 inclusion increases photoluminescence efficiency, suppresses halide segregation, induces thin-film smoothness and uniformity, and reduces crystallite size. Overall, these devices show superior performance among blue perovskite light-emitting diodes (PeLEDs) and general LECs. 相似文献