The design of characterizing-integral schemes and the application to the shallow water wave problems

In this paper a new approach for designing upwind type schemes-the characterizing-integral method and its applied skills are introduced. The method is simple, convenient and eff ective. And the method isn ’t only limited to conservation laws unlike other methods and maybe easily extended to multi-dimension problems. Furthermore, the numerical dissipation of the method can be flexibly regulated, so that it is especially suitable for solving various discontinuity problems.The paper shows us now to use this approach to simulate deformation and breaking of a nonlinear shallow water wave on a gentle slope, and to compute two-dimensional dam failure problem.     

功能梯度材料扁锥壳的热弹性大变形分析

研究了功能梯度材料扁薄锥壳在横向非均匀升温场中的几何非线性大变形问题.基于von Kármán几何非线性理论推导出了以中面位移为基本未知量的功能梯度扁薄锥壳在横向非均匀热载荷作用下的轴对称大挠度控制方程.采用打靶法数值求解所得非线性常微分方程边值问题,得到了锥壳的大挠度弯曲变形数值解.给出了锥壳的变形与其形状参数、载荷和材料参数等变化的特征关系曲线,分析和讨论了温度参数和材料梯度变化参数对变形的影响.     

Comparison of POD reduced order strategies for the nonlinear 2D shallow water equations

This paper introduces tensorial calculus techniques in the framework of POD to reduce the computational complexity of the reduced nonlinear terms. The resulting method, named tensorial POD, can be applied to polynomial nonlinearities of any degree p. Such nonlinear terms have an online complexity of , where k is the dimension of POD basis and therefore is independent of full space dimension. However, it is efficient only for quadratic nonlinear terms because for higher nonlinearities, POD model proves to be less time consuming once the POD basis dimension k is increased. Numerical experiments are carried out with a two‐dimensional SWE test problem to compare the performance of tensorial POD, POD, and POD/discrete empirical interpolation method (DEIM). Numerical results show that tensorial POD decreases by 76× the computational cost of the online stage of POD model for configurations using more than 300,000 model variables. The tensorial POD SWE model was only 2 to 8× slower than the POD/DEIM SWE model but the implementation effort is considerably increased. Tensorial calculus was again employed to construct a new algorithm allowing POD/DEIM SWE model to compute its offline stage faster than POD and tensorial POD approaches. Copyright © 2014 John Wiley & Sons, Ltd.     

Melting and subsolidus phase relations in the system K2CO3–MgCO3 at 3 GPa

ABSTRACT

As part of an investigation of carbonate systems under mantle pressures and temperatures, phase relations in the K₂CO₃–MgCO₃ system have been studied at 3?GPa and 800–1300°C. Subsolidus assemblages comprise the stability fields of K₂CO₃?+?K₂Mg(CO₃)₂ and K₂Mg(CO₃)₂?+?MgCO₃ with the transition boundary near 50?mol% K₂CO₃ in the system. The K₂CO₃–K₂Mg(CO₃)₂ eutectic is located at 840°C and 52?mol% K₂CO₃. The K₂CO₃ content in the melt coexisting with potassium carbonate increases to 85?mol% as temperature increases to 1050°C. K₂CO₃ remains solid up to 1250 and melts at 1300°C. K₂Mg(CO₃)₂ melts incongruently at 890°C to produce magnesite and a liquid containing 51?mol% K₂CO₃. As temperature increases to 1300°C, the K₂CO₃ content in the liquid coexisting with magnesite decreases to 27?mol%.     

大尺度浅水波方程中相互调制的非线性波

基于一般的浅水波方程, 根据大尺度正压大气的特点, 得到无量纲的控制大尺度大气的动力学非线性方程组. 利用多尺度法, 由无量纲的动力学方程组导出了扰动位势的非线性控制方程. 采用椭圆方程构造该扰动位势控制方程的解, 获得了扰动位势和速度的多周期波与冲击波(爆炸波) 并存的解析解. 扰动位势的解表明经向和纬向具有不同周期和波长的周期波, 且都受纬向孤波的调制; 速度的解表明大尺度大气流动存在气旋和反气旋周期性分布的现象. 关键词： 浅水波方程 大尺度正压大气 解析解 非线性波     

总剂量辐照效应对窄沟道SOI NMOSFET器件的影响

本文深入研究了130 nm Silicon-on-Insulator (SOI) 技术下的窄沟道n型metal-oxide-semiconductor-field-effect-transistor (MOSFET) 器件的总剂量辐照效应. 在总剂量辐照下, 相比于宽沟道器件, 窄沟道器件的阈值电压漂移更为明显. 论文利用电荷守恒定律很好地解释了辐照增强的窄沟道效应. 另外, 本文首次发现, 对于工作在线性区的窄沟道器件, 辐照产生的浅沟槽隔离氧化物(STI) 陷阱正电荷会增加沟道区载流子之间的碰撞概率和沟道表面粗糙度散射, 从而导致主沟道晶体管的载流子迁移率退化以及跨导降低. 最后, 对辐照增强的窄沟效应以及迁移率退化进行了三维器件仿真模拟, 仿真结果与实验结果符合得很好. 关键词： 总剂量效应(TID) 浅沟槽隔离(STI) 氧化层陷阱正电荷 SOI MOSFET     

粘性浅水方程柯西问题解的Lp-估计

本文通过对相应线性方程格林函数的估计，而获得粘性浅水方程柯西问题解的Lp渐近估计。     

Solution of shallow water equations using fully adaptive multiscale schemes

The concept of fully adaptive multiscale finite volume methods has been developed to increase spatial resolution and to reduce computational costs of numerical simulations. Here grid adaptation is performed by means of a multiscale analysis based on biorthogonal wavelets. In order to update the solution in time we use a local time stepping strategy that has been recently developed for hyperbolic conservation laws. The adaptive multiresolution scheme is now applied to two‐dimensional shallow water equations with source terms. The efficiency of the scheme is demonstrated on several problems with a general geometry, including circular damp breaks, oblique hydraulic jump, supercritical channel flows encountering sudden change in cross‐section, and, finally, the bore wave and its interactions. Copyright © 2005 John Wiley & Sons, Ltd.     

Improvements in mass conservation using alternative boundary implementations for a quasi‐bubble finite element shallow water model

Finite element approaches generally do not guarantee exact satisfaction of conservation laws especially when Dirichlet‐type boundary conditions are imposed. This article discusses improvement of the global mass conservation property of quasi‐bubble finite element solutions for the shallow water equations, focusing on implementations of the surface‐elevation boundary conditions. We propose two alternative implementations, which are shown by numerical verification to be effective in improving the smoothness of solutions near the boundary and in reducing the mass conservation error. The improvement of the mass conservation property contributes to augmenting the reliability and robustness of long‐term time integrations. Copyright © 2006 John Wiley & Sons, Ltd.     

A preliminary study on sea wave packet equations on slowly varying topography

There is a common hypothesis for the presently popular mild-slope equations that wave particle motion is irrotational. In this paper, an attempt is made to abandon the irrotational assumption and to set up new sea wave packet equations on slowly varying topography by use of the WKBJ method. To simplify the deduction, the two-dimensional shallow water equations are used to describe the sea wave particle motion in the very shallow nearshore area. The established equations can give some characteristics of wave propagation near shore.