ITERATIVE ALGORITHM FOR AXIALLY ACCELERATING STRINGS WITH INTEGRAL CONSTITUTIVE LAW

A numerical method is proposed to simulate the transverse vibrations of a viscoelastic moving string constituted by an integral law. In the numerical computation, the Galerkin method based on the Hermite functions is applied to discretize the state variables, and the Runge- Kutta method is applied to solve the resulting differential-integral equation system. A linear iterative process is designed to compute the integral terms at each time step, which makes the numerical method more efficient and accurate. As examples, nonlinear parametric vibrations of an axially moving viscoelastic string are analyzed.     

POSITIVE SOLUTIONS OF HIGHER DIMENSIONAL DISCRETE BOUNDARY VALUE PROBLEM

By means of the critical point theory, we prove the existence of positive solutions for a higher dimensional discrete boundary value problem. Our results generalize one of Agarwal in [2].     

人工肾透析液进出口处分流片对传质的影响

通过数值模拟，重点考察了人工肾透析液进出口处的分流片对传质的影响．同时对分流片作了改进设计，即将分流片改为同形状的多孔分流片，并研究了随着多孔分流片的Darcy渗透系数K从 ∞减小到O时人工肾清除率的变化趋势．模拟结果显示，随着K降低，清除率先增大后减小，最佳Darcy渗透系数对应的最大清除率比现有人工肾同条件下的清除率提高约4．5％．模拟结果对优化设计人工肾以提高透析效率有重要意义．     

硼元素对人造金刚石单晶氧化速度的影响

 本文用KNO₃溶液氧化法对人造金刚石大单晶切片进行氧化实验，用两光束干涉计测量了单晶（含硼和不含硼）(110)截平面上各晶面成长区沿(110)面法线方向的相对氧化深度，计算了其相对氧化速度，并定性的与硼元素在这些区域的浓度做了对应。     

Preface

Preface

Preface     

A numerical study of cell behaviour in a ternary solution during the freezing process

Using a continuum model for multi-component phase change system, the freezing of cell suspension in a ternary solution, H2O-NaCl-CPA (cryoprotective agent) inside a flat bag is investigated numerically in this study. The temperature and phase change history, intracellular water loss, and the volume change of the cells at different locations inside cell suspension are calculated. Numerical results reveal that although the sample boundary is cooled at a constant rate, different locations inside the sample experienced different temperature changes and cooling rates. The highest cooling rates occur at internal locations. The cell volume change is location-dependent.     

Finite termination of a dual Newton method for convex best <Emphasis Type="Italic">C</Emphasis><Superscript><Emphasis Type="Italic">1</Emphasis></Superscript> interpolation and smoothing

Summary. Given the data (x _i ,y _i )², which are in convex position, the problem is to choose the convex best C ¹ interpolant with the smallest mean square second derivative among all admissible cubic C ¹ -splines on the grid. This problem can be efficiently solved by its dual program, developed by Schmdit and his collaborators in a series of papers. The Newton method remains the core of their suggested numerical scheme. It is observed through numerical experiments that the method terminates in a small number of steps and its total computational complexity is only of O(n). The purpose of this paper is to establish theoretical justification for the Newton method. In fact, we are able to prove its finite termination under a mild condition, and on the other hand, we illustrate that the Newton method may fail if the condition is violated, consistent with what is numerically observed for the Newton method. Corresponding results are also obtained for convex smoothing. Mathematics Subject Classification (2000):41A29, 65D15, 49J52, 90C25The work was supported by the Australian Research Council for the first author and by the Hong Kong Research Grant Council for the second author.     

FeS2能隙的外压微扰调制

 采用基于密度泛函理论的自洽赝势方法，计算了FeS₂在外压调制下的电子结构性质。计算结果表明：随着压缩度的增加，外压调制下的Fe—S键长缩短，FeS₂小的能隙变宽，Fe的d电子与S的p电子杂化增强，原子间相互作用增大。这一能隙随压力增大而增大的结果，与非导体在高压下金属化的特征相反。     

A study of alkali resistance of CaO---Al2O3---SiO2 glasses

The alkali resistance and structure of CaO---Al₂O₃---SiO₂ glasses are studied in this paper. The change of coordination number of aluminum ions in the glasses, caused by corrosion from the cement extract aqueous solution, was determined by means of X-ray fluorescence spectra and infrared absorption spectra. The interrelationship between glass compositions, structure, and alkali resistance is discussed.     

Crystal Structure and Characterization of a Dye with Two-photon Pumped Frequency-upconverted Lasing Properties

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