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301.
在工程制图中,圆柱圆锥正交相贯时,其交线上的某些特殊点总是近似求出.以正投影理论为基础,以圆柱圆锥正交相贯的数学模型为依据,提出了一种准确、简便、可靠的求解方法.方法对于手工或计算机准确绘制该交线、对圆管平交正锥台三通下料等工程问题,都很有实用价值. 相似文献
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Yves Grohens Stephane Ulvé Karine Vallée-Réhel Jean Jacques Péron Dominique Haras 《Macromolecular Symposia》2003,203(1):271-276
Contact angle measurements (captive bubble and sessile drop techniques) were used to determine the surface energy of several acrylic based polymers at the early stage of immersion (t0) in pure and salt water or after several days (tx). The sessile drop technique using various liquid probes allows the calculation of the dispersive, acid and basic components of the surface energy. Significant differences of wettability are observed between the polymers at t0 which tend to remain after immersion along with a general increase of the surface hydrophilicity. The same trend is observed by the “in-situ” captive bubble technique. The surfaces become more hydrophilic with a final contact angle, θ, ranging from 110 to 150 ± 3° in pure water and 130 to 150 ± 4° in 0,51 M salt water. The modifications of surface energy between t0 and tx are not only dependent on water diffusion. One assumption is that the degree of swelling of the immersed surface layer along with the particular dynamics resulting from a surface gel-like structure are significant factors in the measured surface thermodynamics. 相似文献
305.
Wenliang Zhu Jiliang Zhu Mingsong Wang Bo Zhu Xiaohong Zhu Giuseppe Pezzotti 《Journal of Raman spectroscopy : JRS》2012,43(9):1320-1328
A quantitative polarized Raman analysis of ferroelectric grain/domain orientation in LiSbO3 (LS‐modified) (K0.5Na0.5)NbO3 (KNN) ceramics is presented, based on the analysis of the complex orientation dependence in space of their Raman‐active modes. Complete sets of Raman tensor elements of Ag, and Eg phonon modes for orthorhombic/tetragonal structures of KNN have been determined. Through this spectroscopic algorithm, quantitative information could be extracted in terms of three Euler angles in space for KNN samples consisting of mixed phases, thus enabling quantitative visualization of the local distribution of grains/domains in the solid angle. As an application of the method, we quantitatively examined the unknown crystallographic grain orientation patterns on the surfaces of pure KNN and of KNN‐0.05LS ceramics. These two samples were useful to clarify a polymorphic phase transition from the orthorhombic to the tetragonal phase taking place in the LS‐modified KNN system. Thus, we demonstrated that polarized Raman spectroscopy is a valuable and efficient tool for nondestructive three‐dimensional assessments of grain/domain orientation in ferroelectric materials with complex polymorphic structures. We believe that the data shown here represent a typical scenario encountered in grain/domain orientation assessments of piezoelectric perovskites. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献