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61.
A college homework problem, dealing with a loaded transmission line, is reviewed. The setup is then treated as a two-port distributed network. The law of conservation of power is explained with the aid of a scattering theory. Two coupled circuit relations are then formulated. One, associated with the load terminals, is quite different from the conventional equation involving the self impedance and the mutual impedance. An effective impedance function, designated as the scattering impedance, is introduced to facilitate the formulation. The result of applying the Rayleigh/Carson reciprocity theorem to find the expression of the load current is also discussed 相似文献
62.
Zhenfei Tai Samuel Cheng Pramode Verma Yan Zhai 《Journal of Visual Communication and Image Representation》2010,21(7):722-730
There is a significant need for a system to recognize Braille documents in order to preserve them and make them available to a larger group of visually impaired people. A new system for Braille document recognition is proposed. We introduce a highly-adaptive Braille documents parameters estimation method to automatically determine the rotation angle, indentations, and spacing in both vertical and horizontal orientation. The key element in determining the rotation angle of the images is based on Radon transform. Also we introduce the method of Braille translation using Belief Propagation on the assumption that the Braille document is a Hidden Markov Model. We demonstrate the effectiveness of rotation angle correction as well as the accuracy of indentation and spacing in both orientations. We also prove that the translation algorithm is efficient and robust to errors made in the dot detection. The proposed method may be used for further applications. 相似文献
63.
Chen-To Tai 《Antennas and Propagation, IEEE Transactions on》1984,32(4):408-410
The theory of a terminated folded monopole was previously studied by Josephson. The equivalent circuit used by that author was incorrect for a folded monopole when its arms are of different diameters. By using the decomposition scheme suggested by Uda and Mushiake we have solved the problem correctly. The circuit parameters involved in the theory are discussed in detail to supplement the work of Uda and Mushiake. 相似文献
64.
Hau-Yan Lu Ting-Chang Chang Ya-Hsiang Tai Po-Tsun Liu Sien Chi 《Display Technology, Journal of》2007,3(4):398-403
A new pixel design and driving method for active-matrix organic light-emitting diode (AMOLED) display using low-temperature polycrystalline silicon thin-film transistor (LTPS-TFT) is proposed. The new circuit consists of five TFTs and one capacitor to eliminate the variation in the threshold voltage of the TFTs, and the drop in the supply voltage in a single frame operation. The proposed pixel circuit has been verified to realize uniform output current by the simulation work using HSPICE software. The simulated error rate of the output current is also discussed in this paper. The novel pixel design has great potential for use in large size and high resolution AMOLED displays. 相似文献
65.
Wei Yuan Chunyan Li Chen Zhao Chenguang Sui Wan‐Tai Yang Fu‐Jian Xu Jie Ma 《Advanced functional materials》2012,22(9):1835-1842
Efficient local gene transfection on a tissue scaffold is of crucial importance in facilitating tissue repair and regeneration. In this work, the gelatin‐functionalized polycaprolactone (PCL) film surfaces are prepared via surface‐initiated atom transfer radical polymerization of glycidyl methacrylate. The resultant covalent attachment of gelatin could enhance the cell‐adhesion and local gene transfection properties. The gelatin‐functionalized PCL film surfaces exhibit excellent cell‐adhesion ability to both adherent and suspension cells. The attached adherent cells demonstrate the characteristic elongated morphologies with good spreading capability, while the attached suspension cells can maintain the original status of the round morphologies without spreading. More importantly, the gelatin coupled on the PCL surface could be used to absorb the cationic vector/plasmid deoxyribonucleic acid (pDNA) complexes via electrostatic interaction. The local gene transfection property on the immobilized cells is dependent on both the density of the immobilized cells and the loading types of pDNA complexes. The transfection efficiency of different assemble methods of pDNA complex was compared. With the pre‐ and post‐loading sandwich‐like gene transfection, the gelatin‐functionalized PCL film surface can substantially enhance the transfection properties to different cell lines. The present study is very useful to spatially control local gene delivery within PCL‐based tissue scaffolds. 相似文献
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以氮化铝、碳化硅为原料,氧化钇为烧结助剂,在1900℃、氮气气氛中,采用热压烧结工艺制备了AlN-SiC复相微波衰减材料。借助网络分析仪,研究了该材料在8~12GHz的微波衰减性能。结果表明,当SiC质量分数从0增加到9%时,该材料的谐振损耗峰所对应的频率从10.86GHz降低到10.11GHz,所对应的峰值从3.2dB降低到0.7dB,而该材料的有效衰减带增大;在900~1000℃、氢气(纯度≥99.99%)气氛中保温30~50min后,该材料的谐振频率维持在10.65~10.62GHz,谐振峰峰值略微减小;这表明在氢气气氛中的热处理对该材料的微波衰减性能影响较小。 相似文献
70.
随着以太网通信技术的发展,局域网子网间的通信业务增长迅速,而适用于子网间数据通信的传统路由器因为其转发速度慢、用户配置复杂等缺点,难以满足当前大量跨子网以及虚拟局域网之间通信数据量的需求。基于片上系统(System-on-Chip, SoC)平台FMQL45T900型号的FPGA芯片,采用VHDL硬件描述语言,自主研发了12端口的千兆以太网三层交换功能,并已在相应的硬件平台上进行了功能验证和性能测试。实验结果表明,基于固定长度链表的哈希查找方式实现简单、查找高效、复杂度低,该研究成果可在某些需要进行数据灵活交换的特殊的场景下进行应用。 相似文献