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151.
In this note we present a new Rosenbrock solver which is third-order accurate for nonlinear parabolic problems. Since Rosenbrock methods suffer from order reduction when they are applied to partial differential equations, additional order conditions have to be satisfied. Although these conditions have been known for a longer time, from the practical point of view only little has been done to construct new methods. Steinebach modified the well-known solver RODAS of Hairer and Wanner to preserve its classical order four for special problem classes including linear parabolic equations. His solver RODASP, however, drops down to order three for nonlinear parabolic problems. Our motivation here was to derive an efficient third-order Rosenbrock solver for the nonlinear situation. Such a method exists with three stages and two function evaluations only. A comparison with other third-order methods shows the substantial potential of our new method.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
152.
In the short treatise De Motu (1684),which serves as a precursor to the Principia Mathematica (1687),Newton essentially deals with the following two problems. 相似文献
153.
The Hardy operator Ta on a tree is defined by Properties of Ta as a map from Lp() into itselfare established for 1 p . The main result is that, with appropriateassumptions on u and v, the approximation numbers an(Ta) ofTa satisfy for a specified constant p and 1 p < . This extends results of Naimark, Newmanand Solomyak for p = 2. Hitherto, for p 2, (*) was unknowneven when is an interval. Also, upper and lower estimates forthe lq and weak-lq norms of an(Ta) are determined. 2000 MathematicalSubject Classification: 47G10, 47B10. 相似文献
154.
Nous présentons un cadre unificateur pour un certain nombre de résultats connus de convergence en loi pour des processus admettant une représentation linéaire par rapport à un bruit blanc faible pour lequel il existe un principe dinvariance faible. Nous montrons que ce principe dinvariance est équivalent à la convergence dune suite de mesures aléatoires spectrales. Ceci permet daffaiblir les hypothèses usuelles et donc dobtenir des résultats nouveaux de convergence en loi, notamment pour des processus à longue portée. 相似文献
155.
Ambrose D Arroyo C Bachman M Connor D Eckhause M Graessle S Hancock AD Hartman K Hebert M Hoff CH Hoffmann GW Irwin GM Kane JR Kanematsu N Kuang Y Lang K Lee R Martin RD McDonough J Milder A Molzon WR Pommot-Maia M Riley PJ Ritchie JL Rubin PD Vassilakopoulos VI 《Physical review letters》2000,84(7):1389-1392
We report results from Experiment 871, performed at the BNL AGS, of a measurement of the branching ratio K(0)(L)-->&mgr;(+)&mgr;(-) with respect to the CP-violating mode K(0)(L)-->pi(+)pi(-). This experiment detected over 6200 candidate &mgr;(+)&mgr;(-) events, a factor of 6 more than that seen in all previous measurements combined. The resulting branching ratio gamma(K(0)(L)-->&mgr;(+)&mgr;(-))/gamma(K(0)(L)-->pi(+)pi(-)) = (3. 474+/-0.057)x10(-6) leads to a branching fraction B(K(0)(L)-->&mgr;(+)&mgr;(-)) = (7.18+/-0.17)x10(-9), which is consistent with the current world average, and reduces the uncertainty in this decay mode by a factor of 3. 相似文献
156.
温度对金属纳米线势能分布的影响 总被引:3,自引:0,他引:3
采用三维分子动力学模拟方法,以面心立方金属银为研究对象,基于Finnis-Sinclair型嵌入原子法(EAM)多体势,模拟研究了纳米线势能分布特征在常温下及其在不同温度直到熔化过程中的变化,给出了常温及不同温度银纳米线势能分布比例和势能分布函数.结果表明:常温下,纳米线高势能原子比例随纳米线横截面尺寸的减小而增大,势能分布函数曲线各峰位几乎与纳米线横截面尺寸无关;纳米线熔化前的势能分布函数曲线具有多个波峰,随着温度增加,峰数减少且峰位右移;熔化后,多峰特征消失,只有一个宽化的峰. 相似文献
157.
Elastic light scattering by low-dimensional quantum objects without a change in the frequency is theoretically investigated in terms of the quantum perturbation theory. The differential cross section of resonance light scattering from any excitons in any quantum dots is calculated. It is demonstrated that, when the light wavelengths considerably exceed the quantum-dot size, the polarization and angular distribution of the scattered light do not depend on the shape, the size, or the configuration of quantum dots. In this case, the total light scattering cross section is independent of the quantum-dot size. If the radiative damping of an exciton exceeds the nonradiative damping, the total light scattering cross section at resonance is of the order of the light wavelength squared. The radiative damping associated with the long-range exchange interaction between electrons and holes is calculated for any excitons and any quantum dots. 相似文献
158.
A cascaded Fresnel digital hologram (CFDH) is proposed, together with its mathematical derivation. Its application to watermarking has been demonstrated by a simulation procedure, in which the watermark image to be hidden is encoded into the phase of the host image. The watermark image can be deciphered by the CFDH setup, the reconstructed image shows good quality and the error is almost closed to zeros. Compared with previous technique, this is a lensless architecture, which minimizes the hardware requirement. 相似文献
159.
160.
G. I. Baram I. N. Azarova A. G. Gorshkov A. L. Vereshchagin B. Lang E. D. Kiryukhina 《Journal of Analytical Chemistry》2000,55(8):750-754
A technique for the direct preconcentration of bis(2-ethylhexyl) phthalate (DEHP) on a reversedphase analytical column was
proposed for the analysis of water samples by high-performance liquid chromatography (HPLC). A procedure for determining DEHP
in surface-water and atmospheric precipitations in the laboratory and in the field was developed (the limit of detection is
0.1 Μg/L, the limit of determination is 0.3 Μg/L, and the relative standard deviation is 20 or 6% at a DEHP concentration
of 0.3 or 10 Μg/L, respectively). The concentration levels of DEHP as a chemical tracer for the transfer and migration of
air and water masses were examined in Lake Baikal water and in the snow cover of the Baikal region. 相似文献