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31.
FU Xian-song YAO Su-ying YUAN Yi-dong XU Jiang-tao DING Ke YAN Kun-shan 《半导体光子学与技术》2008,14(3):153-157
The logarithmic response complementary metal oxide semiconductor (CMOS) image sensor provides a wide dynamic range, but its drawback is the lack of simple fixed pattern noise(FPN) cancellation scheme. Designed is a novel logarithmic active pixel sensor(APS) with high dynamic range and high output swing. Firstly, the operation principle of mixed-model APS is introduced. The pixel can work in three operation modes by choosing the proper control signals. Then, FPN sources of logarithmic APS are analyzed, and double-sampled technique is implemented to reduce FPN. Finally, according to the simulation results, layout is designed and has passed design rule check(DRC), electronic rule eheck(ERC) and layout versus schematic(LVS) verifications, and the post-simulation results are basically in agreement with the simulation results. Dynamic range of the new logarithmic APS can reach about 140 dB; and the output swing is about 750 inV. Results show that by using double sampled technique, most FPN is eliminated and the dynamic range is enhanced. 相似文献
32.
分析TDaubechies小波系列的频带特性,针对故障诊断信号特征提取的问题,提出了一种改进的小波包算法,并运用该算法对变频调速系统输出电流进行分析。该算法克服了小波包频谱混叠的缺陷且其计算量和占用的存储空间较标准的小波包算法均减少50%.经过仿真证明,该方法适用于变频调速系统故障信号的特征提取。 相似文献
33.
The organic phase of bituminous coals may be represented as a three-dimensional macromolecular network, with chains consisting of aromatic or heterocyclic clusters and smaller connecting bonds, usually of etheric, sulfidicor methylenic nature. The crosslinks are covalently bonded bridges or hydrogen-bonded structures. The molecular weight between crosslinks, [Mbar]C, and other parameters of the crosslinked structure can be calculated using the results of various experiments and applying theories widely used for the analysis of polymeric networks, albeit with significant modifications. 相似文献
34.
Network structure and compositional effects on tensile mechanical properties of hydrophobic association hydrogels with high mechanical strength 总被引:1,自引:0,他引:1
Hydrophobic association hydrogels (HA-gels) were successfully prepared through micellar copolymerization of acrylamide (AM) and a small amount of octylphenol polyoxyethylene acrylate (OP-4-AC) in an aqueous solution containing sodium dodecyl sulfate (SDS). HA-gels exhibited excellent mechanical properties and transparency. Especially, HA-gels possessed the capability of re-forming, such as self-healing and molding. From Fourier transform infrared, swelling behavior and re-forming capability of HA-gels, the network structure was established. On the basis of the micellar copolymerization theory, the statistical molecular theory of rubber elastic, and using uniaxial stretching data, the length of the hydrophobic microblocks, the effective network chain density and the molecular weight of the chain length between cross-linking points were evaluated for all HA-gels; furthermore, they were also evaluated for the region of medium deformation by the Mooney-Rivlin theory. For HA-gels, we investigated in detail the effects of the content of compositions in the initial solution, OP-4-AC, SDS and AM, on their tensile mechanical properties on the basis of the proposed network structure. The results clearly indicate their tensile strength, fracture energy, elastic modulus, and elongation strongly depended on their composition content. 相似文献
35.
李直 《计算机光盘软件与应用》2011,(20)
随着社会经济的蓬勃发展,我国的公路系统也越来越发达。网络给公路收费系统带来便利的同时,也带来了危机。本文对公路联网收费系统常见网络故障进行了分析,并提出了相关解决措施。 相似文献
36.
Shao Junpeng Jia HuijuanDepartment of Mechanical Engineering Harbin University of Scienceand Technology Harbin China 《机械工程学报(英文版)》2004,17(1):25-27
A method is proposed for the analysis of vibration signals from components of rotating machines, based on the wavelet packet transformation (WPT) and the underlying physical concepts of modulation mechanism. The method provides a finer analysis and better time-frequency localization capabilities than any other analysis methods. Both details and approximations are split into finer components and result in better-localized frequency ranges corresponding to each node of a wavelet packet tree. For the purpose of feature extraction, a hard threshold is given and the energy of the coefficients above the threshold is used, as a criterion for the selection of the best vector. The feature extraction of a vibration signal is accomplished by computing the reconstruction signal and its spectrum. When applied to a rolling bear vibration signal feature extraction, the proposed method can lead to be very effective. 相似文献
37.
38.
OMRON PLC网络与通信 总被引:2,自引:4,他引:2
可编程控制器与上位计算机组成的集散控制系统越来越广泛应用于生产过程自动化领域。本文介绍了OM—RONPLC的网络硬件组成及特点;通信模式;通信程序。 相似文献
39.
40.
人工神经网络与失效评定图在压力容器安全评定中的应用 总被引:9,自引:1,他引:8
采用人工神经网络与失效评定图相结合的方法对压力容器进行安全评定,样本评定结果和R6 失效评定图方法的评定结果一致,并对评定结果进行了参数敏感性分析,分析结果令人满意。人工神经网络为压力容器安全评定智能化提供了一个有效的手段。 相似文献