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61.
Summary The distribution equilibria of cationic compounds in reversed-phase chromatographic systems (ion-pair chromatography) have
been studied on the basis of their effect on a detectable mobile phase component. The solid phase was a polystyrene-divinylbenzene
copolymer and the detectable component, a quaternary ammonium ion, 1-methylpyridine. The solutes were mono- and divalent amines
and quaternary ammonium ions.
The cations can be retained by ion-pair adsorption and ion exchange. Expressions for the ion-pair retention of the solutes
and the mobile phase cation (system peak) have been developed assuming Langmuir distribution of ion pairs to a solid phase
with one kind of binding site. The validity of the expressions has been tested by evaluation of ion-pair distribution constants
using non-linear curve fitting techniques. Good agreement for the constants of common ion pairs was obtained from different
kinds of capacity ratio expressions.
Ion exchange retention can appear beside ion-pair retention, and it has been observed in the pH range 1.6–6.1. The effect
depends not only on cations in the mobile phase, but also on the nature of the buffering systems. 相似文献
62.
Response of saturated porous media subjected to local thermal loading on the surface of semi-infinite space 总被引:2,自引:0,他引:2
Bing Bai 《Acta Mechanica Sinica》2006,22(1):54-61
Heat source function method is adopted in the present paper to derive elementary solutions of coupled thermo-hydro-mechanical
consolidation for saturated porous media under conjunct actions of instantaneous point heat source, instantaneous point fluid
source and constant volume force. By using the so-called fictitious heat source method and images method, the solutions of
a semi-infinite saturated porous medium subjected to a local heat source with time-varied intensity on its free surface are
developed from elementary solutions. The numerical integral methods for calculating the unsteady temperature, pore pressure
and displacement fields are given. The thermomechanical response are analyzed for the case of a circular planar heat source.
Besides, the thermal consolidation characteristics of a saturated porous medium subjected to a harmonic thermal loading are
also given, and the fluctuation processes of the field variables located below the center of heat source are analyzed.
The project supported by the National Natural Science Foundation of China (50578008) The English text was polished byYunming
Chen. 相似文献
63.
64.
有限元计算中疏密网格过渡方法研究 总被引:1,自引:0,他引:1
工程计算中出于节省计算量的目的,往往需要在一个有限元模型中布置粗细不同的网格。为保证计算结果的准确性,必须保证网格突变情况下的位移协调问题。本文工作之一是在强天驰界面过渡单元的基础上,引入虚拟节点和子单元,在子单元中应用节理元思想,提出了基于最小势能原理的弹簧节理单元法。简化了积分运算,避免了精度要求极高的坐标转换,从而提高了方法的精度和实用性;二是提出了基于位移约束的主从自由度法,简便实用,只需简单的矩阵运算即可实现。两种方法均实现了不同尺寸网格间位移的协调性和刚度的匹配,从而使之满足有限元收敛准则,且生成的刚度阵具有对称性及带状性。算例证明两种方法精度良好,并可方便地应用于求解大规模工程问题。 相似文献
65.
介绍了计算伏秒消耗的玻印亭方法,并通过扫描等离子体电流爬升率对伏秒消耗进行了优化分析。分析结果对EAST装置长脉冲稳态放电提供一定的参考。 相似文献
66.
The longitudinal motions and vertical accelerations of a floating torus as well as wave motion inside the torus are studied by model tests in regular deep-water waves. Comparisons are made with linear and partly with second-order potential-flow theory for the smallest examined experimental wave height-to-wave length ratio 1/120. Reasonable agreement is obtained, in particular for the linear problem. The importance of 3D flow, hydroelasticity and strong hydrodynamic frequency dependency is documented. Experimental precision errors and bias errors, for instance, due to tank-wall interference are discussed. Numerical errors due to viscous effects are found to be secondary. Experiments show that the third and fourth harmonic accelerations of the torus matter and cannot be explained by a perturbation method with the wave steepness as a small parameter. 相似文献
67.
Peter E.J. Vos Claes Eskilsson Alessandro Bolis Sehun Chun Robert M. Kirby 《International Journal of Computational Fluid Dynamics》2013,27(3):107-125
Time-stepping algorithms and their implementations are a critical component within the solution of time-dependent partial differential equations (PDEs). In this article, we present a generic framework – both in terms of algorithms and implementations – that allows an almost seamless switch between various explicit, implicit and implicit–explicit (IMEX) time-stepping methods. We put particular emphasis on how to incorporate time-dependent boundary conditions, an issue that goes beyond classical ODE theory but which plays an important role in the time-stepping of the PDEs arising in computational fluid dynamics. Our algorithm is based upon J.C. Butcher's unifying concept of general linear methods that we have extended to accommodate the family of IMEX schemes that are often used in engineering practice. In the article, we discuss design considerations and present an object-oriented implementation. Finally, we illustrate the use of the framework by applications to a model problem as well as to more complex fluid problems. 相似文献
68.
We consider the problem of recovering a two-dimensional periodic structure from scattered waves measured above the structure. Following an approach by Kirsch and Kress, this inverse problem is reformulated as a nonlinear optimization problem. We develop a theoretical basis for the reconstruction method in the case of an arbitrary Lipschitz grating profile. The convergence analysis is based on new perturbation and stability results for the forward problem. 相似文献
69.
Formation and movement of an exciton pulse in an inhomogeneous potential are studied. It is shown that the pulse does not blur and the maximum of the exciton density in the pulse remains constant during the exciton lifetime if the pulse is formed from the condensed phase. The path, traversed by the excitons, can be increased by imposing an additional laser pulse on the system. Thereby, such a system can be used for information transmission over the exciton condensed phase. 相似文献
70.