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71.
72.
In general, this paper deals with general nonlinear oscillations of a nonconservative and single degree-of-freedom system with odd nonlinearity and, in particular, it presents accurate higher-order analytical approximate solutions to van der Pol damped nonlinear oscillators having odd nonlinearity and the Rayleigh equation. By combining the linearization of the governing equation with harmonic balancing and the method of averaging, we establish accurate analytical approximate solutions for the general weakly damped nonlinear systems. Unlike the classical harmonic balance method, simple linear algebraic equations instead of nonlinear algebraic equations are obtained upon linearization prior to harmonic balancing. The combination of these two methods results in very accurate transient response of the periodic solution. In addition and for the first time, this paper also presents a method for deducing fourth-, fifth- and higher-order linearized governing equations from the lower-order equations without the requirement of formulating the problem from the first principle. Three examples including the van der Pol damped nonlinear oscillator are presented to illustrate the excellent agreement with approximate solution using the exact frequency. 相似文献
73.
Rafael Gallego Lucia Comino Alberto Ruiz‐Cabello 《International journal for numerical methods in engineering》2006,66(12):1913-1933
In this paper, the material constant sensitivity boundary integral equation is presented, and its numerical solution proposed, based on boundary element techniques. The formulation deals with plane problems with general rectilinear anisotropy. Expressions for the computation of sensitivities for displacements, tractions, strains and stresses are derived, both for boundary and interior points. The sensitivities can be computed with respect to the bulk material properties or to the properties of part of the domain (inclusions, coatings, etc.). To assess the accuracy of the proposed approach, the computed results are compared to analytical ones derived from exact solutions obtained by complex potential theory, when possible, or finite difference derivatives otherwise. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
74.
双组分树脂冷压法制备摩擦材料 总被引:8,自引:0,他引:8
研究甲、乙双组分液体树脂作为粘结剂制备制动摩擦材料的冷压工艺方法,甲组分树脂为硼改性腰果壳油树脂,乙组分树脂为三聚氰胺改性酚醛树脂。该工艺可使模压料在室温下具有良好的成型效果,在固化处理中不使用夹具,可以使成型料具有良好的保型效果。冷压制备的制动摩擦材料具有硬度低、摩擦系数稳定和恢复性好等特点。 相似文献
75.
76.
The objective of this paper is to present an analysis on the scale‐up procedure of two‐dimensional spouted beds. The task was carried out with three different beds measuring 0.15, 0.30 and 0.80 in width. The conditions of scale‐up were studied through geometrical similitude analysis. Some parameters of scale were adimensionalised, tested and validated in order to propose relationships capable of predicting values of dependent properties. Those relationships should be followed in a prototype of an equipment of industrial scale. The study permitted the development of correlations to predict values of maximum pressure drop, minimum spout velocity and maximum height of spouting. 相似文献
77.
底部框剪砌体房屋空间弹塑性地震反应分析 总被引:10,自引:3,他引:7
本文提出了底部框剪砌体房屋这类上下混合承重结构体系的空间弹塑性地震反应时程分析方法。针对砌体结构和框架抗震墙结构截然不同的抗震性能,对上部砌体结构采用空间剪扭分析法,而对下部框架抗震墙结构采用空间协同分析法,建立了组合型串联刚片系振动模型。对单向和双向地震波输入结构层位移反应进行了比较。 相似文献
78.
79.
Kum‐Il Lee Yong‐Sik Yim Sang‐Wook Chung Jiaqiu Wei Jong Il Rhee 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(9):1036-1045
A two‐dimensional (2D) spectrofluorometer was used to monitor various fermentation processes with recombinant E coli for the production of 5‐aminolevulinic acid (ALA). The whole fluorescence spectral data obtained during a process were analyzed using artificial neural networks, ie self‐organizing map (SOM) and feedforward backpropagation neural network (BPNN). The SOM‐based classification of the whole spectral data has made it possible to qualitatively associate some process parameters with the normalized weights and variances, and to select some useful combinations of excitation and emission wavelengths. Based on the classified fluorescence spectra a supervised BPNN algorithm was used to predict some of the process parameters. It was also shown that the BPNN models could elucidate some sections of the process's performance, eg forecasting the process's performance. Copyright © 2005 Society of Chemical Industry 相似文献
80.
产品图象智能检测技术研究 总被引:3,自引:1,他引:2
工业界对图象智能检测技术有着迫切的需要。本文通过对火腿肠产品在线感官质量检测关键性技术的深入研究,证实了该项技术住火腿肠类产品在线感官检测中应用的可行性,文中重点讨论了产品图象智能判别系统的硬软件结构、图象检测判别万法、检测实验数据及实验结果分析。 相似文献