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排序方式: 共有1101条查询结果,搜索用时 15 毫秒
101.
The construction and convergence of high-order product integration methods for the second-kind Abel equation are discussed and the results of De Hoog and Weiss are generalised. Backward difference methods are introduced, and numerical results are presented which verify the theoretical rates of convergence. 相似文献
102.
在再生核空间中给出一类二阶非线性偏微分方程的一个新的求解方法,近似解un(x)是通过在再生核空间中截断精确解u(x)而得到的,最后,通过一个数值算例来说明该方法是有效的. 相似文献
103.
Cui-E Hu Zhao-Yi Zeng Chun-Yang Kong Yu-Ting Cui Lin Zhang 《Physica B: Condensed Matter》2012,407(24):4671-4675
We employ the spin-polarized generalized gradient approximation within the density functional theory to investigate the equation of state, magnetism and elastic constant of cubic ACrO3 (A=Pb, Ca, Sr, and Ba) perovskite. The antiferromagnetic phase is the most stable state at zero pressure. Under pressure, the ferromagnetic state will transform to the non-magnetic state. Considering the effect of magnetism, the equilibrium lattice constant, the bulk modulus and the high pressure equations of state agree well with the available experiments. By using the energy-strain method, the predicted elastic properties are satisfactory. 相似文献
104.
王雪梅 《数学的实践与认识》1998,(2)
本文借助laplace变换及不动点理论,研究了系统(?)=Ax+integral from n=0 to t(c(t-s)x(s)ds)+F(t,x)的周期解的存在性。唯一性问题,给出了一组充分条件. 相似文献
105.
L. P. Falaleev 《Mathematical Notes》2000,67(4):505-511
We obtain a sharp value for the constant in the leading term of the deviation of a function belonging to the class Lip1 α from the generalized Abel-Poisson operators specified by the summation factors
of the conjugate Fourier series in the case 0 < α <l ≤ 1.
Translated fromMatematicheskie Zametki, Vol. 67, No. 4, pp. 595–602, April, 2000. 相似文献
106.
We have studied the structural behavior of lead monoxide (PbO) as a function of pressure via angular dispersive X-ray diffraction employing two different pressure transmitting media that were quasi-hydrostatic (N2) and non-hydrostatic (MgO), respectively. Besides litharge (-PbO) and massicot (β-PbO), which are both stable at ambient pressure, there is an orthorhombic γ-PbO phase which appears upon application of pressure to -PbO. We have found that the orthorhombic γ-PbO phase is favored by shear stress under non-hydrostatic conditions. -PbO shows strong anisotropy in compressibility. The a-axis is rather incompressible with a linear stiffness coefficient of Ka0=540(30) GPa whereas the c-axis stiffness is Kc0=25(1) GPa. The bulk modulus of -PbO is K0=23.1(3) GPa and its derivative . 相似文献
107.
Talbot Michael Katz 《Journal of statistical physics》1985,38(3-4):589-602
Gates and Penrose have given criteria under which classical gases with weak long-range interactions fail to be described by the van der Waals equation with Maxwell's rule. Unfortunately, examples of equations of state for such systems have not yet been produced. This paper examines the Gates-Penrose class of interactions-i.e.,U
(r)=q(r)+(r), in the limit0, where the Fourier transform
(p) has a minimum at a nonzero value ofp-for the spherical model on a one-dimensional lattice. Free energy and magnetization isotherms are computed; it is seen that there is a phase transition, but that the zero-field spontaneous magnetization is always zero (a parahelicoidal phase). However, the pair-correlation function may exhibit either long-range order or the appearance of oscillation. 相似文献
108.
Uri. Goldberg 《International Journal of Computational Fluid Dynamics》2013,27(1):27-38
A new topography-parameter-free turbulence closure, based on a transport equation for the pseudo eddy viscosity, is described. The model is tested against experimental data of several flow cases across the Mach number range and compared to Menter's single equation model and to the Spalart-Allmaras model. The main conclusion is that the new closure outperforms the other two models in both low and high speed flows. 相似文献
109.
Humberto Hinojosa-GómezAuthor Vitae J. Fernando Barragán-ArocheEnrique R. Bazúa-RuedaAuthor Vitae 《Fluid Phase Equilibria》2010
In this work we present two modifications to the Peng–Robinson-Fitted equation of state where pure component parameters are regressed to vapor pressure and saturated liquid density data. The first modification (PR-f-mod) is a method that enhances the equation of state pure component property predictions through simple temperature dependent pure component parameters. In the second modification (PR-f-prop) we propose a temperature dependency for co-volume b in the repulsive parameter of the EoS, and revise the temperature function in the attractive term. The agreement with experimental data for 72 pure substances, including highly polar compounds, is remarkably good. We obtain average absolute deviations in saturated liquid density of less than 1% for all substances studied. 相似文献
110.
Using a similar approach as Lencka and Anderko [AIChE J. 39 (1993) 533], we developed an equation of state for hydrogen fluoride (HF), which can correlate the vapor pressure, the saturated liquid and vapor densities of it from the triple point to critical point with good accuracy. We used an equilibrium model to account for hydrogen bonding that assumes the formation of dimer, hexamer, and octamer species as suggested by Schotte [Ind. Eng. Chem. Process Des. Dev. 19 (1980) 432]. The physical and chemical parameters are obtained directly from the regression of pure component properties by applying the critical constraints to the equation of state for hydrogen fluoride. This equation of state together with the Wong–Sandler mixing rule as well as the van der Waals one-fluid mixing rule are used to correlate the phase equilibria of binary hydrogen fluoride mixtures with HCl, HCFC-124, HFC-134a, HFC-152a, HCFC-22, and HFC-32. For these systems, new equation of state with the Wong–Sandler mixing rule gives good results. 相似文献