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991.
Abstract The phase diagram of a mixture of the discogens triphenylene hexa-n-heptanoate (HET7) and triphenylene hexa-(2-methyl-4-n-decyloxy)benzoate is presented. This mixture provides a more accessible nematic temperature range than was previously possible. The refractive indices of one mixture composition are measured and a rather small, negative birefringence found. The two-parameter Haller extrapolation method is used to calculate the molecular polarizability ratio Δα/α. This has a rather small magnitude compared with calamitic mesogens, although the individual polarizabilities are much larger, due to the greater molecular mass of these compounds. The calculated value of Δα/α is used to give the uniaxial orientational order parameter S, whose value is comparable to those of calamitic examples. Tabulated bond polarizability data are used to predict a value for Δα/α, which is found to be similar to the experimental result. 相似文献
992.
993.
We analyse different error propagation mechanisms for conservativeand nonconservative time-integrators of nonlinear Schrödingerequations. We use a geometric approach based on interpretingwaves as relative equilibria. 相似文献
994.
GUAN Xiang-guo DU Yong LI Yun-liang WaiMing Kwok David Lee Phillips 《光散射学报》2005,17(3):261-262
pacc:8240,8250F TheultravioletphotolysisofCH2I2wasstud iedinwater[1-3]andsaltwatersolutionsusing photochemistryandpicosecondtime-resolved resonanceRamanspectroscopy.Photolysisinboth typesenvironmentsproducesmainlyCH2(OH)2andHIproducts.However,photolysisof… 相似文献
995.
996.
997.
On the effects of a compressible viscous lubricant on the load‐bearing capacity of a journal bearing
A compressible viscous isothermal model is presented for studying journal‐bearing lubrication. The viscosity in the model thickens with increasing density. The governing equations are written in terms of velocity, the natural logarithm of the density and the kinematic extra‐stress tensor. A semi‐Làgrangian treatment of the material derivatives is combined with a spectral element discretization in space. The roles of the speed of sound and the eccentricity ratio on the load‐bearing capacity of the journal bearing are investigated. Compressibility is shown to enhance the load‐bearing capacity and this effect is amplified as the eccentricity ratio approaches unity. It is shown that for speeds of sound in the region of those of multigrade oils, the dominant component of the force on the journal acts along the line joining the centres of the bearing and journal and in the direction away from the narrow gap. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
998.
George M. Phillips 《BIT Numerical Mathematics》1997,37(1):232-236
This paper is concerned with a generalization of the classical Bernstein polynomials where the function is evaluated at intervals
which are in geometric progression. It is shown that these polynomials can be generated by a de Casteljau algorithm, which
is a generalization of that relating to the classical case.
Dedicated to M. J. D. Powell on the occasion of his 60th birthday 相似文献
999.
Michael K. Kinyon J. D. Phillips 《Proceedings of the American Mathematical Society》2004,132(3):617-619
In this note we show that the commutant of a Bol loop of odd order is a subloop.
1000.
Jack R. Frautschi Joseph A. Chinn Richard E. Phillips Jr. Q.H. Zhao James M. Anderson Ravi Joshi Robert J. Levy 《Colloids and surfaces. B, Biointerfaces》1993,1(5)
This study compares and contrasts mechanisms of polyetherurethane (PEU) degradation in vitro and in vivo. Models comprising incubation with hydrogen peroxide in vitro (H2O2), in vivo subcutaneous rat implant (SUBQ), and subcutaneous rat cage implant (CAGE) are described and compared with in vivo degradation of the pacemaker lead device retrieved after human implant (PACE). Experimental results support the hypothesis that stress accelerates PEU degradation. Scanning electron microscopy (SEM), gel permeation chromatography (GPC), and Fourier transform IR spectroscopy/attenuated total reflectance (FT-1R/ATR) evaluation of tested PEU samples suggests, for all models, decreased soft segment and increased ester functionality at the polymer surface. These observations are consistent with a single, metal ion catalyzed, polyester intermediate, oxidative degradation mechanism common to all models, and with device performance in vivo. Model comparison suggests that in vitro H2O2 and in vivo SUBQ and CAGE models accurately mimic in vivo degradation of the pacemaker lead device (PACE). 相似文献