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81.
对高速运动环境下多普勒效应引起的大载波频偏引起的载波间干扰进行数学分析,建立带频偏的非时变和时变频偏OFDM动态状态空间模型,提出了基于平方根无迹卡尔曼滤波(square-root unscented Kalman filter , SR-UKF)的频偏估计算法。将非线性状态估计思想引入OFDM频偏估计中,实现了对频偏的有效跟踪和估计。仿真结果表明,在大频偏、高阶调制下,SR-UKF频偏估计算法较自消除算法、最大似然估计算法具有更好的误码率性能;在收敛精度、稳定度和对信噪比敏感度方面,性能较扩展卡尔曼滤波算法均有所提升。 相似文献
82.
A series of waterborne poly(urethane‐urea)s, WPUUs, based on using nonpolar hydroxyl‐terminated polybutadiene (HTPB) as the soft segment, were successfully synthesized in this article. The effects of the COOH group content and soft‐segment molecular weight (Mns) on the dispersion, morphology, and physical properties were investigated. Variations of the particle size, viscosity, and zeta potential were first governed by the hydrophilicity of the polymer chain, and then by the swelling derived from water. Fourier transfer infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated that the degree of phase separation decreased as the COOH group content increased or as Mns decreased. However, the hydrogen bonding between the soft and hard segments and the two‐phase mixing could not occur in this nonpolar HTPB‐based WPUU system, indicating that the hard segments tended to form smaller domains and to pack more loosely. It was attributed to the fact that the presence of bulky ionic salt groups destroyed the ordered arrangement of the hard segments. In this case, the increases of the interface area between the soft and hard phases resulted in that the present behaviors were similar to the phase mixing. In tensile properties, HTPB‐based WPUUs exhibited higher tensile stress, elongation at break, and modulus as the COOH group content decreased or as Mns decreased. In thermal degradation, the introduction of HTPB polyol improved the thermal stability of WPUU. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
83.
A series of new sesquiterpene ketones and norsesquiterpene ketones could be identified from the cephalic secretion of females of the cuckoo bee,Nomada lathburiana (K.). The major component proved to be 2,6,10-trimethylundeca-(5E)-2,5,9-trien-4-one. Large amounts of high-boiling-point straight-chain hydrocarbons serve as solvents for the volatile, unstable ketones. 相似文献
84.
CPL: Detecting Protein Complexes by Propagating Labels on Protein-Protein Interaction Network 下载免费PDF全文
Proteins usually bind together to form complexes, which play an important role in cellular activities. Many graph clustering methods have been proposed to identify protein complexes by finding dense regions in protein-protein interaction networks. We present a novel framework (CPL) that detects protein complexes by propagating labels through interactions in a network, in which labels denote complex identifiers. With proper propagation in CPL, proteins in the same complex will be assigned with the same labels. CPL does not make any strong assumptions about the topological structures of the complexes, as in previous methods. Tile CPL algorithm is tested on several publicly available yeast protein-protein interaction networks and compared with several state-of-the-art methods. The results suggest that CPL performs better than the existing methods. An analysis of the functional homogeneity based on a gene ontology analysis shows that the detected complexes of CPL are highly biologically relevant. 相似文献
85.
本文介绍了一步法制备取代2-四氢萘酮的新方法,与常规合成方法相比,该法具有明显的优点:不需要先将羧酸转化成酰氯,避免了三氯化铝以及含氯溶剂的应用,并使催化剂得以循环利用。因此,该方法安全、环保,有望取代常规的付-克反应在工业上的应用。 相似文献
86.
Carbon/carbon composites were made through the pyrolysis of stabilized PAN felt and phenolic resin with the addition of 5 or 10 wt % carbon black to the matrix and then heat treatment at 600–2500°C. The effects of adding carbon black to the matrix precursor on the physical properties, microstructure, and mechanical properties of the resultant composites were investigated. Adding carbon black not only reduced the weight loss but also limited the shrinkage of the resultant composites. Adding carbon black also accelerated the formation of carbon basal planes in the matrix. At 2500°C, the crystalline stacking height in the composite with 10 wt % added carbon black was 200% greater than that with no additive. The flexural strength of the composite also increased from 15 to 42 MPa (almost 300%). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 333–337, 2006 相似文献
87.
通过失重法和极化曲线、线性极化两种电化学方法,研究了十二烷基二甲基(2-羟基)乙基氯化铵(122)、十四烷基二甲基(2-羟基)乙基氯化铵(142)和十六烷基二甲基(2-羟基)乙基氯化铵(162)对20#碳钢在5%盐酸中的缓蚀作用。并与新洁尔灭(十二烷基二甲基苄基溴化铵)进行了比较。结果表明,它们在酸性介质中具有很好的缓蚀作用。 相似文献
88.
近些年来,环氧沥青混合料以其耐久性好、强度高、冲击韧性优越等特点,广泛地应用于大型桥梁桥面铺装之中.以TAF-10型环氧沥青混合料为研究对象,对其进行不同温度与频率下的动态模量试验,结合时温等效原理,通过Origin数学计算软件,采用西格摩德(Sigmoidal)模型对试验结果进行非线性拟合;并通过高温车辙试验、小梁弯曲试验及冻融劈裂试验,对其高温稳定性、低温抗裂性、水稳定性等路用性能进行检测.结果表明:随着加载频率的增大,TAF-10环氧沥青混合料的动态模量不断增大,而随试验温度的升高其值不断减小;拟合所得到的主曲线方程,可以对任何给定温度与加载频率下该种混合料的动态模量进行有效预估;TAF-10环氧沥青混合料的高温稳定性、低温抗裂性及水稳定性等性能均超出规范要求,满足桥面铺装要求.研究成果可以为TAF-10环氧沥青混合料桥面铺装的动态设计提供参考. 相似文献
89.
90.
Claudia Kuster Jean‐Charles Bazin Cengiz Öztireli Teng Deng Tobias Martin Tiberiu Popa Markus Gross 《Computer Graphics Forum》2014,33(2):1-10
Multi‐view reconstruction aims at computing the geometry of a scene observed by a set of cameras. Accurate 3D reconstruction of dynamic scenes is a key component for a large variety of applications, ranging from special effects to telepresence and medical imaging. In this paper we propose a method based on Moving Least Squares surfaces which robustly and efficiently reconstructs dynamic scenes captured by a calibrated set of hybrid color+depth cameras. Our reconstruction provides spatio‐temporal consistency and seamlessly fuses color and geometric information. We illustrate our approach on a variety of real sequences and demonstrate that it favorably compares to state‐of‐the‐art methods. 相似文献