基于二次插值的非饱和土壤水流问题的特征差分方法及数值模拟

本文针对一类非饱和土壤水流问题,提出了基于二次插值的特征差分格式,得到了严谨的L2模误差估计.并作了数值试验,指明方法的有效性.     

The solution of a convection–diffusion–reaction equation arising from cathodic reduction in a pulsating crack

This paper derives the convection–diffusion-reaction equation governing the reaction between the dissolved oxygen in sea-water and the steel walls of a pulsating crack. By the neglect of the diffusion term it is shown that an exact solution of the convection-reaction equation can be obtained. A numerical method for the solution of the complete convection–diffusion-reaction equation is derived by the use of finite differences. The numerical computation of the initial transient and the final periodic steady-state values is also discussed.     

特征线法在求解非线性液相吸附色谱模型中的应用

本文应用特征线法求解非线性液相吸附色谱分离过程模型，论述了特征线法的原理和步骤，讨论了时间步长和空间步长对模型数值解的影响，并用色谱分离甘露醇和山梨醇以及分离蔗糖和还原糖的实验进行验证，用特征线法计算的理论流出曲线与实验流出线吻合较好。本文还分折了模型中各个参数的灵敏度，结果表明：吸附等温方程Q＝Ci*／（ai＋biCi*）中参数ai比参数bi以及总传质系数ki有更高的灵敏度。     

Characteristics of Ag/Bi<Subscript>3.25</Subscript>La<Subscript>0.75</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript>/p-Si heterostructure prepared by sol-gel processing

The metal-ferroelectric-semiconductor (MFS) heterostructure has been fabricated using Bi_3.25La_0.75Ti₃O₁₂ (BLT) as a ferroelectric layer by sol-gel processing. The effect of annealing temperature on phase formation and electrical characteristics of Ag/BLT/p-Si heterostructure were investigated. The BLT thin films annealed at from 500°C to 650°C are polycrystalline, with no pyrochlore or other second phases. The C-V curves of Ag/BLT/p-Si heterostructure annealed at 600°C show a clockwise C-V ferroelectric hysteresis loops and obtain good electrical properties with low current density of below 2×10⁻⁸ A/cm² within ±4 V, a memory window of over 0.7 V for a thickness of 400 nm BLT films. The memory window enlarges and the current density reduces with the increase of annealing temperature, but a annealing temperature over 600°C is disadvantageous for good electrical properties.     

飞秒激光冲击AZ31B镁合金过程的数值模拟

采用有限元分析法对飞秒激光冲击AZ31B镁合金进行数值模拟,研究了激光冲击处理对镁合金变形过程的影响,分析了单脉冲激光冲击下材料内部的位移、动能、应力和应变的分布情况,得到了材料的瞬态速度和应变率变化过程.仿真结果表明,单脉冲飞秒激光冲击镁合金产生的塑性变形,可在材料表面形成微米级凹坑,中心点处最大位移为34μm,最大变形速度390m/s;在冲击初期,材料表面的应力和应变主要分布在冲击区域中心节点和边缘附近,并且得到镁合金的最大应力和最大应变率分别为955 MPa和1.8×106 s-1.研究结果能够为深入分析飞秒激光与镁合金作用时材料变形参量的变化规律提供数值理论依据.     

PLD法生长n-Zn1-xCoxO/p-Si异质结的电学性能研究

用高功率脉冲激光轰击Zn1-xCoxO,得到锌、钴和氧的原子、分子和团簇等混合体,并在p型单晶Si表面反应生成n型Zn1-xCoxO.X射线衍射(XRD)、原子力显微镜(AFM)研究表明,这层材料是结构致密均匀、呈c轴高度择优取向的薄膜,与p型Si材料形成n-Zn1-xCoxO/p-Si异质结.在Zn1-xCoxO中加入H,生成了Co-H-Co聚合体,异质结的势垒高度随着Co含量的增加而增加,同时深能级的Co-d轨道捕获作为浅施主的间隙H提供的电子,造成的体系n型半导体层的载流子浓度降低,电阻率提高,使得n-Zn1-xCoxO/p-Si异质结在6.5V时漏电流降致6×10-3 mA,反向击穿电压超过20V,电学性能得到显著改进.     

四元数矩阵理论中的几个概念间的关系

本文指出并改正文［１］中的错误，给出弱特征多项式［２］与重特征多项式［３］间的显式关系，同时也给出行列式［２］与重行列式［４］间的显式关系，最后讨论了左特征值、右特征值、特征值和特征根之间的关系及最小多项式与弱特征多项式根之间的关系．     

赤潮光谱特征及其形成机制

采用海面以上光谱测量方法 (Above water method),利用美国FieldSpec® Dual VNIR光谱仪测量了丹麦细柱藻、中肋骨条藻、海洋褐胞藻等三种浮游植物赤潮以及红色中缢虫这一原生动物赤潮的离水辐射光谱数据。强调赤潮与正常海水的光谱差异在于687～728 nm波段的特征反射峰,指出了浮游植物赤潮与原生动物赤潮间的显著光谱差异,并认为可据此进行某些赤潮种类的遥感识别。给出了浮游植物赤潮光谱反射峰、吸收峰成因;红色中缢虫这一原生动物引起的水色异常,与其体内的共生藻类及浮游植物色素碎屑有关;其摄食偏好、与藻类的共生特性研究以及藻类常温下的荧光发射特性研究,将有助于加深对于红色中缢虫赤潮光谱成因的认识。     

Asymptotic behavior of solutions to scalar conservation laws and optimal convergence orders to N-waves

The goal of this article is to develop a new technique to obtain better asymptotic estimates for scalar conservation laws. General convex flux, f″(u)?0, is considered with an assumption . We show that, under suitable conditions on the initial value, its solution converges to an N-wave in L¹ norm with the optimal convergence order of O(1/t). The technique we use in this article is to enclose the solution with two rarefaction waves. We also show a uniform convergence order in the sense of graphs. A numerical example of this phenomenon is included.     

HL—1装置电流上升段辐射与杂质特性

托卡马克等离子体中的杂质会影响托卡马克的放电品质及等离子体特性。许多理论和实验对杂质的产生和输运做了深入详细的研究。等离子体电流起始阶段,由于约束性能不好,会引起大量的杂质产生,辐射损失增大是杂质增加引起的直接后果。杂质辐射是等离子体辐射的主要组成部分之一,等离子体线辐射功率～Z_(eff)~6,复合辐射功率～Z_(eff)~4,轫致辐