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1.
Galvanic corrosion over a semi-infinite, planar surface 总被引:1,自引:0,他引:1
Mark Verbrugge 《Corrosion Science》2006,48(11):3489-3512
We derive the governing equations for the galvanic coupling of two dissimilar materials in a planar surface wherein the transport phenomena in the liquid phase are controlled by ionic migration or diffusion. The problem statement corresponds to two semi-infinite materials located in the same plane and coupled along a single boundary, resulting in a two-dimensional analysis. A single dimensionless group arises in the analyses of the corrosion problems, which greatly simplifies the presentation of numerical results and subsequent implementation. An example application of this work is presented that demonstrates how the results can be used to set requirements for protective films (e.g., paint) utilized for reducing corrosion rates. 相似文献
2.
3.
小波变换在管道弱超声回波奇异性检测中的应用 总被引:2,自引:0,他引:2
研究了小波变换在细尺度下检测信号奇异性的原理。通过对样管中标准缺陷的超声回波分析试验,证明6层db5小波变换可以有效地分离出湮没在噪声中的微弱缺陷信号,并可以有效地分离出信号的孤立奇异点,准确定位缺陷出现时刻。 相似文献
4.
以3-TPT并联机构作为研究对象,建立该机构的运动学正、反解方程,求出该机构的雅可比矩阵及其逆矩阵,并在此基础上运用MATLAB软件和LabVIEW软件对该机床的奇异性、灵,5性和平稳性性进行仿真分析。仿真结果表明:3-TPT并联机构不存在奇异位形,并且拥有较好的灵巧性和平稳性,这为并联机构的最优化设计及控制系统设计提供了理论基础,并为确定工作形位和机构尺寸提供了设计依据。 相似文献
5.
Philippe Flajolet's research in theoretical computer science spans over more than 20 years. He made lasting contributions
to the analysis of algorithms and analytic combinatorics. Among many of his results we mention here some in such diversified
topics as enumeration, number theory, formal languages, continued fractions, automatic analysis of algorithms, Mellin transform,
digital sums, recurrences, trees, random generation of combinatorial objects, random graphs and mappings, polynomial factorization,
communications, codes, graphics, etc. This gives only a small snapshot of his work, and we encourage the reader to visit Flajolet's
homepage http://www-rocq.inria.fr/algo/flajolet/index.html for a fuller account. The bibliography was taken from his homepage
and may not be totally complete, although we added a few items. Our paper was written without giving any prior notice to Philippe
Flajolet. It reflects the view of the authors and any misunderstandings and shortcomings should be put on their account. 相似文献
6.
Singularity is a fundamental problem with robotic manipulators. Various methods of singularity handling have been published in the past. In this paper, a singularity robust method is presented and its implementation issues discussed. It focuses on the discontinuity problem inherent in the singularity robust techniques with removal of degenerate components. Sources of the discontinuity are discussed and the null motion is proposed as the means of providing a continuous control of the end-effector over the boundary of the singular region. The presentation of this paper covers a complete treatment of singularities, starting from identifications of the singular configurations and the associated singular directions, the handling algorithm and the discontinuity issues. The algorithm was implemented on PUMA 560. The experimental results are presented and discussed. 相似文献
7.
高压电器设备的故障大多与绝缘有关,而局部放电是造成绝缘损坏的主要原因之一。如何有效地从噪声和干扰中准确提取局部放电信号的特征,是绝缘故障在线检测的关键。针对高压电缆中的局部放电信号检测问题,提出了一种基于小波包的奇异信号检测方法。首先,分析后得到窄带信号和奇异的放电信号在小波包变换下会表现出截然不同的特性,然后利用这个特性,采用小波包的方法有效地抑制窄带干扰,并从噪声中提取出奇异的局部放电信号。仿真结果显示出在两项指标中,同步性指标大于99%,相似性指标大于90%,这证明了该算法能够从噪声和干扰中,有效地检测并提取出高压电缆中的局部放电信号。 相似文献
8.
为解决现有方法在处理微带线边缘电磁场的奇异性时,存在计算效率和精度之间的矛盾,该文提出一种在局部1维时域有限差分法(LOD-FDTD)基础上,结合微带线边缘电磁场分布函数,并通过坐标变换可处理导体嵌入网格面积大于1/2时的情况,因而适用性更广的微带线边缘奇异性处理技术。与现有奇异性处理技术对比证明,该算法在采用的时间步长小于等于Courant-Friedrichs-Lewy(CFL)稳定性条件所允许最大时间步长5倍的情况下,具有更高的计算精度。且与一般LOD-FDTD算法对比证明,引入的微带线边缘电磁场分布函数使得该算法在节省计算资源和提高计算效率的同时,保持了更高的计算精度。 相似文献
9.
10.
Chattering free full-order sliding-mode control 总被引:3,自引:0,他引:3
In conventional sliding-mode control systems, the sliding-mode motion is of reduced order. Two main problems hindering the application of the sliding-mode control are the singularity in terminal sliding-mode control systems and the chattering in both the conventional linear sliding-mode and the terminal sliding-mode control systems. This paper proposes a chattering-free full-order terminal-sliding-mode control scheme. Since the derivatives of terms with fractional powers do not appear in the control law, the control singularities are avoided. A continuous control strategy is developed to achieve the chattering free sliding-mode control. During the ideal sliding-mode motion, the systems behave as a desirable full-order dynamics rather than a desirable reduced-order dynamics. A systematic design method of full-order sliding-mode control for nonlinear systems is presented, which allows both the chattering and singularity problems to be resolved. Simulations validate the proposed chattering free full-order sliding-mode control. 相似文献