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81.
82.
Digital i mages are extensively used because of itsfeatures of visibility and abundanceininformation ex-pression. Along with the development of the Inter-net ,the security of storage andtransmission of digitali mages are becoming more and morei mportant .As anapproach of i mage encryption, digital i mage scram-blingtechnologyis aresearchemphasis all through.Itcan be used directlyin digital encryption,andcanalsobe used as the preprocessing and post processing toenhance the robustness of digital… 相似文献
83.
Adaptive Noise Cancellation Method Used for Wheel Speed Signal of Integrate ABS/ASR System 总被引:2,自引:0,他引:2
The anti-lock braking system (ABS) and anti-slip regulation system(ASR) are the very i mportantparts of active safety systems used for modern vehi-cles . This two systems make up of commonintegratesystem ABS/ASR[1 ,2]. At present ,the main controlmethodin ABS/ASRis the logic threshold method.When getting the wheel speed signal ,ECUcomputesand applies control after comparing current signalwith the threshold[3 -5].Because of many reasons ,the wheel speed sig-nals sampled in ABS/ASRalw… 相似文献
84.
Watermarking,as a technique for copyright pro-tection,has drawn significant attention from manyresearchers and there has been intensive research inthis areainrecent years.Robustness of watermarkingstill remains one of the key issues for practical appli-cations.Aserious problemconstrainingsome practicalexplorations of watermarking technologyis the insuf-ficient robustness of existing watermarking algorithmsagainst geometric distortionsuch as rotation,scaling,and translation(RST),etc[1].Designi… 相似文献
85.
高熔体强度聚丙烯(high melt strength polypropylene,HMSPP)是具有较高熔体强度和弹性、在熔融拉伸时存在应变硬化现象的一种新型聚丙烯材料。近年来,对长支链(LCB)型HMSPP(LCB-HMSPP)的研发引起了学术界和工业界的广泛关注。在利用各种方法和工艺制备LCB-HMSPP之后,所得聚合物是否具有长支链结构,长支链的化学组成、密度及链长度等拓扑结构信息,都需要通过各种仪器分析与表征方法对其进行定性或定量验证。本文着重对傅里叶变换红外光谱(FTIR)法、核磁共振碳谱(13C NMR)法、凝胶渗透色谱(GPC)及其联用方法、流变学表征法和结晶行为表征法在LCB-HMSPP中LCB链结构分析与表征中的研究新进展进行总结和评述,介绍了这些方法各自的优缺点和适用性并对这些方法进行了对比,最后对用于LCB-HMSPP中LCB链结构的分析与表征方法研究的未来发展及应用前景进行了展望。 相似文献
86.
Yao Wang Pei-feng Hsu Yingsang Wu 《International Journal of Applied Ceramic Technology》2022,19(4):2311-2321
Thermal barrier coatings (TBCs) using yttria-stabilized zirconium dioxide (YSZ) are widely used in gas turbines to protect metal components against the high combustion product temperature. Increasing combustion temperature and pressure, radiative heat transfer becomes an essential portion of the overall heat transfer in TBCs. This necessitates a greater understanding of the thermal radiative properties of YSZ films, especially in the near-infrared wavelength range. The commonly used Kubelka–Munk (KM) method in the radiative property reduction from the measured transmittance and reflectance spectra of YSZ films can incur inaccurate results when the coating optical thickness is not sufficiently large. The discrete ordinates method with the asymmetric spherical ring angular quadrature can solve the radiative transfer equation with good accuracy in optically thin media. Considering the solution accuracy and computational efficiency, a hybrid approach of combining the KM and discrete ordinate methods is used to invert radiative properties. The absorption and scattering coefficients of air plasma sprayed YSZ films are determined over the wavelength range from 1 to 2.6 μm at room temperature. Over this near-infrared wavelength range, the scattering coefficient decreases with the increasing wavelength, and the absorption coefficient is very small overall. 相似文献
87.
采用傅立叶变换红外光谱(FTIR),研究了聚[(2,2′-间-苯基)-5,5′-二苯并咪唑](简称聚苯并咪唑,PBI)膜及其磷酸掺杂膜分别在N2、空气氛围中的热降解过程,并与这2种膜的热失重分析结果进行对比.结果发现,在N2中直到450℃时PBI的结构都没有大的变化,而在空气中达450℃时PBI结构发生了变化.从磷酸掺杂PBI膜的FTIR发现,除了PBI结构变化外,磷酸在其中的存在形态也随着温度的升高而变化.在温度升高过程中掺杂体系中的H2PO4-逐渐减少,而H3PO4则逐渐增多. 相似文献
88.
89.
Displacements and stresses due to a vertical point load in an inhomogeneous transversely isotropic half-space 总被引:1,自引:0,他引:1
C. D. Wang C. S. Tzeng E. Pan J. J. Liao 《International Journal of Rock Mechanics and Mining Sciences》2003,40(5):667-685
We present the solutions for displacements and stresses subjected to a vertical point load in a continuously inhomogeneous transversely isotropic half-space with Young's and shear moduli varying exponentially with depth. Planes of transverse isotropy are assumed to be parallel to the horizontal surface. The solutions for the half-space are obtained by superposing the solutions of two full spaces, one with a point load in its interior and the other with opposite traction of the first full space along the z=0 plane. The Hankel transform in a cylindrical co-ordinate system is employed for deriving the solutions. However, the resulting integrals for displacements and stresses involve polynomial, exponential function, and Bessel function that cannot be given in closed form; hence, numerical techniques are adopted in this work. In order to check the accuracy of numerical procedures, the comparisons are carried out with the homogeneous solutions of Liao and Wang, and the calculated results agree with those to nine decimal places. Furthermore, two illustrative examples are presented to elucidate the effect of inhomogeneity, and the type and degree of rock anisotropy on the vertical surface displacement and vertical normal stress in the inhomogeneous isotropic/transversely isotropic rocks subjected to a vertical concentrated force acting on the surface. The calculated results show that the induced displacement and stress are decisively influenced by the inhomogeneity, and the degree and type of material anisotropy. The proposed solutions can more realistically simulate the actual stratum of loading problem in many areas of engineering practice. 相似文献
90.
针对目前电压暂降检测方法存在的的精确性低、实时性较差的缺点,提出了一种基于改进dq变换与顺序形态滤波器相结合的暂降检测新方法。研究论述了改进dq变换用于电压暂降检测的算法基本原理,介绍了顺序形态学概念,并由此基础设计了形态学滤波器,同时阐述了滤波器参数的选取方法。通过设置不同的信噪比与超前角度,仿真论证了新方法在理想条件和非理想条件下的暂降检测效果,并与传统方法进行了比较和分析。证明了新方法可以更高效精确地检测到暂降的特征值和起止时间。 相似文献