The numerical integration of relative equilibrium solutions. The nonlinear Schrodinger equation

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.     

甲基卤化物的脱卤研究以及在盐溶液(NaCl)环境中通过紫外光分解CH_2I_2制备强酸(英文)

pacc:8240,8250F TheultravioletphotolysisofCH2I2wasstud iedinwater[1-3]andsaltwatersolutionsusing photochemistryandpicosecondtime-resolved resonanceRamanspectroscopy.Photolysisinboth typesenvironmentsproducesmainlyCH2(OH)2andHIproducts.However,photolysisof…     

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.     

A de Casteljau algorithm for generalized Bernstein polynomials

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     

Commutants of Bol loops of odd order

In this note we show that the commutant of a Bol loop of odd order is a subloop.

     

Degradation of polyurethanes in vitro and in vitro: comparison of different models

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).