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41.
简要阐述了当前企业环境的特点,分析了大批量定制及其可拓学模型;然后,从可拓学中的可拓工程出发,以“系列化”、“变型结构设计”和“变型工艺设计”为例,说明了可拓学在实施大批量定制中的应用,为企业寻找新的、有效的大批量定制实施方法提供料新的思路和工具。 相似文献
42.
In this paper, the effectiveness of the approximate motion equations of a flexible structure, obtained by the RitzKantorovich method, is analysed by using Lyapunov functions. The analysis, which is restricted to the case of a single flexible beam for the sake of simplicity, is carried out under the assumption that a partial dissipation is present, affecting only the first degrees of freedom of the system. By means of suitable Lyapunov functions, an overbounding estimate of the quadratic approximation error is determined as a decreasing function of the approximation order. The analysis is completed by considering the two ‘extreme’ cases: the theoretical absence of dissipation and the presence of structural dissipation, affecting all the infinite degrees of freedom. 相似文献
43.
共轭高分子三阶非线性光学材料 总被引:3,自引:0,他引:3
概述了n-共轭高分子材料的三阶非线性光学性质,着重讨论了化学结构对其光学非线性的影响,说明了n-共轭聚合物的三阶非线性极化率主要取决于共轭主链的结构,侧链取代基的变化对其非线性影响不大,文中展望了共轭高分子材料在集成光学中的应用前景。 相似文献
44.
L. FAN‡ D. PATERSON† I. McNULTY‡ M. M. J. TREACY & J. M. GIBSON‡ 《Journal of microscopy》2007,225(1):41-48
Measuring medium‐range order is a challenging and important problem in the structural study of disordered materials. We have developed a new technique, fluctuation x‐ray microscopy, that offers quantitative insight into medium‐range correlations in disordered materials at nanometre and larger length scales.In this technique, which requires a spatially coherent x‐ray beam, a series of speckle patterns are measured at a large number of locations in a sample using various illumination sizes. Examination of the speckle variance as a function of the illumination spot size allows the structural correlation length to be measured. To demonstrate this technique we have studied polystyrene latex spheres, which serve as a model for a dense random‐packed glass, and for the first time have measured the correlation length in a disordered system by fluctuation X‐ray microscopy. We discuss data analysis and procedures to correct for shot noise and detector noise. This approach could be used to explore medium‐range order and subtle spatial structural changes in a wide range of disordered materials, from soft matter to nanowire arrays, semiconductor quantum dot arrays and magnetic materials. 相似文献
45.
The static and dynamic properties of solutions of a side chain polysiloxane liquid crystal polymer have been studied in a cyanobiphenyl nematic host as a function of concentration and temperature. Refractive index measurements were carried out on aligned samples and the data used to determine the macroscopic order parameter, S, using Haller's method. Photon correlation spectroscopy has been used to measure () for the pure nematic solvent and the solutions. From these measurements it appears that the static properties vary slowly and linearly with increasing polymer concentration whilst the dynamic or viscoelastic properties change markedly. This change has been attributed to γ1, the twist viscosity, and the results have been discussed in terms of the function of the siloxane polymer backbone. 相似文献
46.
47.
Bernolet Sarah; Hartsuiker Robert J.; Pickering Martin J. 《Canadian Metallurgical Quarterly》2007,33(5):931
Studies on syntactic priming strongly suggest that bilinguals can store a single integrated representation of constructions that are similar in both languages (e.g., Spanish and English passives; R. J. Hartsuiker, M. J. Pickering, & E. Veltkamp, 2004). However, they may store 2 separate representations of constructions that involve different word orders (e.g., German and English passives; H. Loebell & K. Bock, 2003). In 5 experiments, the authors investigated within- and between-languages priming of Dutch, English, and German relative clauses. The authors found priming within Dutch (Experiment 1) and within English as a 2nd language (Experiments 2 and 4). An important finding is that priming occurred from Dutch to German (Experiment 5), which both have verb-final relative clauses; but it did not occur between Dutch and English (Experiments 3 and 4), which differ in relative-clause word order. The results suggest that word-order repetition is needed for the construction of integrated syntactic representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
In [4,7,9,12], classes of nonlinear systems are considered for which observers can be designed. Although observability of nonlinear systems is known to be dependent on the input, the proposed observers have the property that the estimation error decays to zero irrespective of the input. In the first part of this paper, it is shown that this phenomenon follows from a common property of these systems: for all of them, the “unobservable states” with respect to some input, are in some sense “stable” (in the linear case, these systems are called detectable), and for this reason, a reduced order observer can be designed. In the second part is given a more general class of nonlinear systems for which such an observer can be designed. 相似文献
49.
This article presents a design of the internal model control(IMC)based single degree of freedom(SDF) fractional order(FO)PID controller with a desired bandwidth specification for a class of fractional order system(FOS). The drawbacks of the SDF FO-IMC are eliminated with the help of the two-degree of freedom(TDF)FO PID controller. The robust stability and robust performance of the designed controller are analyzed using an example. 相似文献
50.
脉冲噪声环境下宽带循环平稳信号DOA估计算法 总被引:1,自引:1,他引:0
针对传统二阶循环相关算法在脉冲噪声环境中的显著退化问题,本文以α稳定分布为噪声模型,提出基于分数低阶循环相关的波达方向(Direction of arrival,DOA)估计算法。利用分数低阶循环相关的相移特性,将宽带循环平稳信号的DOA估计问题转化为"中心频率"为ε的窄带问题,解决了宽带情况下DOA估计困难的问题。计算机仿真结果进一步验证了此算法的有效性,且性能优于传统SC-SSF(Spectral correlation signal subspacefitting)算法。 相似文献