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871.
Gashinova M.S. Goubina M.N. Guoyong Zhang Kolmakov I.A. Kolmakov Y.A. Vendik I.B. 《Microwave Theory and Techniques》2003,51(3):792-795
This paper presents design and measurement results of a high-T/sub c/ superconducting planar filter based on a pair of coupled modified hairpin resonators considered to be a key constituent of the filter structure. This provides the filter characteristics, which are very close to the Chebyshev prototype of the same order. 相似文献
872.
基于数字化二次曝光干涉的光学元件波前畸变测量 总被引:1,自引:1,他引:0
将傅立叶变换条纹分析方法与二次曝光全息干涉计量相结合,提出了数字化二次曝光干涉术,用于测量光学元件引入的波前畸变。文中给出了理论分析,模拟与光学实验结果证实提出的方法具有高精度、快速的波前测量特点,可应用于激光系统中光学元件的波前畸变在线检测。 相似文献
873.
介绍了太阳电池应用的一般要求和太阳能供电系统的组成及运行,给出了工程设计个常用的太阳电池容量计算方法,并提出太阳能供电系统运行维护注意事项。 相似文献
874.
875.
With video compression standards such as MPEG‐4, a transmission error happens in a video‐packet basis, rather than in a macroblock basis. In this context, we propose a semantic error prioritization method that determines the size of a video packet based on the importance of its contents. A video packet length is made to be short for an important area such as a facial area in order to reduce the possibility of error accumulation. To facilitate the semantic error prioritization, an efficient hardware algorithm for face tracking is proposed. The increase of hardware complexity is minimal because a motion estimation engine is efficiently re‐used for face tracking. Experimental results demonstrate that the facial area is well protected with the proposed scheme. 相似文献
876.
J.K.J. vanDuren X. Yang J. Loos C.W.T. Bulle‐Lieuwma A.B. Sieval J.C. Hummelen R.A.J. Janssen 《Advanced functional materials》2004,14(5):425-434
The performance of bulk‐heterojunction solar cells based on a phase‐separated mixture of donor and acceptor materials is known to be critically dependent on the morphology of the active layer. Here we use a combination of techniques to resolve the morphology of spin cast films of poly(p‐phenylene vinylene)/methanofullerene blends in three dimensions on a nanometer scale and relate the results to the performance of the corresponding solar cells. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and depth profiling using dynamic time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) clearly show that for the two materials used in this study, 1‐(3‐methoxycarbonyl)propyl‐1‐phenyl‐[6,6]‐methanofullerene (PCBM) and poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene vinylene] (MDMO‐PPV), phase separation is not observed up to 50 wt.‐% PCBM. Nanoscale phase separation throughout the film sets in for concentrations of more than 67 wt.‐% PCBM, to give domains of rather pure PCBM in a homogenous matrix of 50:50 wt.‐% MDMO‐PPV/PCBM. Electrical characterization, under illumination and in the dark, of the corresponding photovoltaic devices revealed a strong increase of power conversion efficiency when the phase‐separated network develops, with a sharp increase of the photocurrent and fill factor between 50 and 67 wt.‐% PCBM. As the phase separation sets in, enhanced electron transport and a reduction of bimolecular charge recombination provide the conditions for improved performance. The results are interpreted in terms of a model that proposes a hierarchical build up of two cooperative interpenetrating networks at different length scales. 相似文献
877.
H.‐G. Boyen G. Kstle K. Zürn T. Herzog F. Weigl P. Ziemann O. Mayer C. Jerome M. Mller J.P. Spatz M.G. Garnier P. Oelhafen 《Advanced functional materials》2003,13(5):359-364
Starting with Co‐salt‐loaded inverse micelles, which form if the diblock copolymer polystyrene‐block‐poly(2‐vinylpyridine) is dissolved in a selective solvent like toluene and CoCl2 is added to the solution, monomicellar arrays of such micelles exhibiting a significant hexagonal order can be prepared on top of various substrates with tailored intermicellar distances and structure heights. In order to remove the polymer matrix and to finally obtain arrays of pure Co nanoparticles, the micelles are first exposed to an oxygen plasma, followed by a treatment in a hydrogen plasma. Applying in‐situ X‐ray photoelectron spectroscopy, it is demonstrated that: 1) The oxygen plasma completely removes the polymer, though conserving the original order of the micellar array. Furthermore, the resulting nanoparticles are entirely oxidized with a chemical shift of the Co 2p3/2 line pointing to the formation of Co3O4. 2) By the subsequent hydrogen plasma treatment the nanoparticles are fully reduced to metallic Co. 3) By exposing the pure Co nanoparticles for 100 s to various oxygen partial pressures pequation/tex2gif-inf-5.gif, a stepwise oxidation is observed with a still metallic Co core surrounded by an oxide shell. The data allow the extraction of the thickness of the oxide shell as a function of the total exposure to oxygen (pequation/tex2gif-inf-7.gif × time), thus giving the opportunity to control the ferromagnetic–antiferromagnetic composition of an exchange‐biased magnetic system. 相似文献
878.
悬浮床加氢裂化油溶性催化剂与沥青质的作用 总被引:1,自引:1,他引:0
在高压釜反应器中对添加了油溶性 Ni 催化剂(UPC-O)和水溶性 Ni 催化剂(UPC-W)的辽河稠油常压渣油(LHAR)进行了悬浮床加氢裂化实验。通过元素分析和傅里叶变换红外光谱(FTIR)分析对抑制反应生焦效果好的 UPC-O 与 LHAR 沥青质的作用进行了研究。元素分析结果显示,在 LHAR 中加入 UPC-O1000μg/g,沥青质和脱沥青质油中 Ni 含量分别出476μg/g和110μg/g 增加到7 559μg/g 和1 024μg/g,表明 UPC-O 在沥青质中有富集的趋势。FTIR 表征结果显示,UPC-O 和沥青质发生了相互作用。UPC-O 可在沥青质原位硫化为活性组分,对沥青质在悬浮床加氢裂化反应中的缩合起到好的抑制作用。 相似文献
879.
880.