Control methods for problems of mixing and coherence in chaotic maps and flows

We review a variety of control methods which are capable of enhancing the chaoticity and mixing properties of chaotic flows and also methods which work towards promoting the coherence properties of such flows. We discuss a parameter control method which can enhance the chaoticity and the rate of mixing of dissipative as well as conservative flows and outline methods which promote global mixing by the addition of noise and by preventing island formation. As the inverse side of this problem, we summarize methods which can create coherent structures in chaotic dynamical flows. We also discuss the utility of these methods from the point of view of applications as well as for understanding phenomena which occur in natural systems.     

Hybrid numerical methods in static and dynamic fracture mechanics

In this article, the concept of the hybrid numerical methods is clarified. On the basis of this concept, various hybrid numerical methods used in static and dynamic fracture mechanics are classified into five categories: (i) hybrid experimental–numerical methods, (ii) hybrid numerical–experimental methods, (iii) hybrid analytical–numerical methods, (iv) hybrid numerical–analytical methods, and (v) hybrid numerical–numerical methods. Features of each category of hybrid numerical method are presented with pertinent numerical results.     

MRI segmentation: Methods and applications

The current literature on MRI segmentation methods is reviewed. Particular emphasis is placed on the relative merits of single image versus multispectral segmentation, and supervised versus unsupervised segmentation methods. Image pre-processing and registration are discussed, as well as methods of validation. The application of MRI segmentation for tumor volume measurements during the course of therapy is presented here as an example, illustrating problems associated with inter- and intra-observer variations inherent to supervised methods.     

MRS signal quantitation: a review of time- and frequency-domain methods

In this paper an overview of time-domain and frequency-domain quantitation methods is given. Advantages and drawbacks of these two families of quantitation methods are discussed. An overview of preprocessing methods, such as lineshape correction methods or unwanted component removal methods, is also given. The choice of the quantitation method depends on the data under investigation and the pursued objectives.     

基于光的反射与折射定律的表述方法推导及应用

光的反射和光的折射是几何光学应用中最基本的方法。在现代精密光学元件加工过程中,其不同的表述方法可以为光线追迹、棱镜误差分析以及棱镜装调提供不同的解决思路。介绍了光的反射定律和折射定律的传统形式表述方法,并推导了光的反射定律和折射定律的矢量、矩阵及四元数3种表述方法。通过Matlab辅助下的模拟计算,得到施密特棱镜检验光路中2个不同区域入射光线的反射在水平方向上对称分布于前表面反射像两侧,与实际应用相符,实现了矢量、矩阵和四元数表述方法在施密特棱镜检验光路中的应用。3种表述方法可以为光线追迹、棱镜误差分析以及棱镜装调提供科学、实用的解决方法。     

Analytic treatment of linear and nonlinear Schrödinger equations: A study with homotopy-perturbation and Adomian decomposition methods

In this work, two powerful analytical methods, called homotopy-perturbation method (HPM) and Adomian decomposition method (ADM) are introduced to obtain the exact solutions of linear and nonlinear Schrödinger equations. The main objective is to propose alternative methods of solution, which do not require small parameters and avoid linearization and physically unrealistic assumptions. The results show that these methods are very efficient and convenient and can be applied to a large class of problems. The comparison of the methods shows that although the numerical results of these methods are the same, HPM is much easier, more convenient and efficient than ADM.     

Bending and acoustic waves in a water-filled box studied by pulsed TV holography and LDV

Pulsed TV holography and laser Doppler vibrometry (LDV) are non-destructive and non-contacting methods useful in the testing of mechanical properties in a wall separating two media. This paper presents comparative studies of transient, propagating bending waves in an impact-loaded thin aluminium wall of a box, and acoustic waves generated in the water inside the box using the two mentioned methods. Besides being evaluated and compared, the results were used to investigate qualities of the methods for the specific applications. The measured wave propagations obtained from the two methods are consistent regarding both amplitude and phase. Further, transient pressure fields in the water have been computed from the pulsed TV holography measurements. Since none of the two methods are capable of providing both temporal and spatial information simultaneously, they complement each other.     

Application of variational iteration method and homotopy–perturbation method for nonlinear heat diffusion and heat transfer equations

Perturbation methods depend on a small parameter which is difficult to be found for real-life nonlinear problems. To overcome this shortcoming, two new but powerful analytical methods are introduced to solve nonlinear heat transfer problems in this Letter; one is He's variational iteration method (VIM) and the other is the homotopy–perturbation method (HPM). Nonlinear convective–radiative cooling equations are used as examples to illustrate the simple solution procedures. These methods are useful and practical for solving the nonlinear heat diffusion equation, which is associated with variable thermal conductivity condition. Comparison of the results obtained by both methods with exact solutions reveals that both methods are tremendously effective.     

块结构自适应网格上任意区域和任意界面的数值积分

研究块结构自适应网格上计算任意界面上和任意区域内的数值积分方法,其中任意界面和任意区域通过一个水平集函数表示.首先介绍在一致网格上任意界面上和任意区域内的数值积分方法.然后,将该方法推广到块结构的自适应网格上.数值算例表明,自适应网格方法有二阶精度.同一致网格方法相比,自适应网格方法显著地减少了计算机存储量的需求.     

全光网络的攻击与检测方法研究

全光网络是未来信息网的核心。人们在对其优越性能进行研究的同时发现它存在安全上的隐患。针对全光网络普遍采用的物理结构,分析了全光网络的主要攻击类型和检测方法,提出了两种新的检测方法,并与传统检测方法进行了比较。     

Design and management of lithium-ion batteries:A perspective from modeling,simulation,and optimization

Although the lithium-ion batteries(LIBs) have been increasingly applied in consumer electronics, electric vehicles,and smart grid, they still face great challenges from the continuously improving requirements of energy density, power density, service life, and safety. To solve these issues, various studies have been conducted surrounding the battery design and management methods in recent decades. In the hope of providing some inspirations to the research in this field, the state of the art of design and management methods for LIBs are reviewed here from the perspective of process systems engineering. First, different types of battery models are summarized extensively, including electrical model and multi-physics coupled model, and the parameter identification methods are introduced correspondingly. Next, the model based battery design methods are reviewed briefly on three different scales, namely, electrode scale, cell scale, and pack scale. Then, the battery model based battery management methods, especially the state estimation methods with different model types are thoroughly compared. The key science and technology challenges for the development of battery systems engineering are clarified finally.     

类金刚石薄膜及其进展

为了使研究者能更详细地了解类金刚石（DLC）薄膜的研究现状,综述了类金刚石薄膜的特性及应用,分析对比了目前常用的一些类金刚石薄膜的制备方法,包括物理气相沉积法（PVD）和化学气相沉积法（CVD）,并对类金刚石薄膜的抗强激光损伤特性以及提高其激光损伤阈值的方法进行了论述。结果发现,利用PVD法制备的DLC膜的硬度可以达到40 GPa~80 GPa,且薄膜的残余应力可以达到0.9 GPa~2.2 GPa之间,而CVD法则由于反应气体的充入导致类DLC薄膜的沉积速率大大降低,故使用率不高。同时,优化膜系的电场强度设计,采用合理的制备工艺,进行激光辐照后处理,施加外界电场干预均可有效地提高DLC薄膜的抗激光损伤能力, 且目前的DLC薄膜的激光损伤阈值可达到2.4 J/cm2。     

Linearly implicit methods for nonlinear PDEs with linear dispersion and dissipation

The linear stability of IMEX (IMplicit–EXplicit) methods and exponential integrators for stiff systems of ODEs arising in the discrete solution of PDEs is examined for nonlinear PDEs with both linear dispersion and dissipation, and a clear method of visualization of the linear stability regions is proposed. Predictions are made based on these visualizations and are supported by a series of experiments on five PDEs including quasigeostrophic equations and stratified Boussinesq equations. The experiments, involving 24 IMEX and exponential methods of third and fourth order, confirm the predictions of the linear stability analysis, that the methods are typically limited by small eigenvalues of the linear term and by eigenvalues on or near the imaginary axis rather than by large eigenvalues near the negative real axis. The experiments also demonstrate that IMEX methods achieve comparable stability to exponential methods, and that exponential methods are significantly more accurate only when the problem is nearly linear. Novel IMEX predictor–corrector methods are also derived.     

Nonlinear Stability and B-convergence of Additive Runge-Kutta Methods for Nonlinear Stiff Problems

In this paper, we are devoted to nonlinear stability and B-convergence of additive Runge-Kutta (ARK) methods for nonlinear stiff problems with multiple stiffness. The concept of ($θ$,$\bar{p}$,$\bar{q}$)-algebraic stability of ARK methods for a class of stiff problems $K_{σ,τ}$ is introduced, and it is proven that this stability implies some contractive properties of the ARK methods. Some results on optimal B-convergence of ARK methods for $K_{σ,0}$ are given. These new results extend the existing ones of RK methods and ARK methods in the references. Numerical examples test the correctness of our theoretical analysis.     

大气光学遥感监测技术现状与发展趋势

针对开展环境空气中的痕量污染气体监测研究的需求,综述了目前应用较广的光谱遥感监测技术。阐述了利用光学遥感技术监测大气环境的工作原理,详细介绍了几种主流的大气监测技术,包括傅里叶变换红外光谱技术,差分吸收光谱技术,激光长程吸收技术,可调谐激光二极管吸收光谱技术,差分吸收激光雷达技术,指出了上述监测方法的特点并对它们的优缺点进行了分析与比较。     

Symplectic and multisymplectic numerical methods for Maxwell’s equations

In this paper, we compare the behaviour of one symplectic and three multisymplectic methods for Maxwell’s equations in a simple medium. This is a system of PDEs with symplectic and multisymplectic structures. We give a theoretical discussion of how some numerical methods preserve the discrete versions of the local and global conservation laws and verify this behaviour in numerical experiments. We also show that these numerical methods preserve the divergence. Furthermore, we extend the discussion on dispersion for (multi)symplectic methods applied to PDEs with one spatial dimension, to include anisotropy when applying (multi)symplectic methods to Maxwell’s equations in two spatial dimensions. Lastly, we demonstrate how varying the Courant–Friedrichs–Lewy (CFL) number can cause the (multi)symplectic methods in our comparison to behave differently, which can be explained by the study of backward error analysis for PDEs.     

Spectrophotometric and Fluorimetric Methods for the Determination of Methoxamine Hc1 in Bulk Drugs and in Ampoules

Abstract

Three simple and sensitive methods for the determination of methoxamine HCl in bulk drugs and in ampoules were proposed. The methods are based on the oxidation of methoxamine HCl by sodium periodate, potassium permanganate and cerium(IV)sulphate. The first two reactions are followed spectrophotometrically by measuring the absorbance at 352 &; 608 nm for the periodate and permanganate methods, respectively. The third method is based on measuring the relative fluorescence intensity of Ce(III)arising from Ce(IV) at 348 nm with excitation wavelength at 257 nm. The different experimental parameters were carefully studied. Under the described conditions the proposed methods were applicable over the concentration ranges 10.0 - 40.0, 2.0-10.0 and 0.05-0.30 μg ml^?1 for the three methods, respectively.     

应用于高性能光学薄膜表征的光热光声检测技术

本文介绍了光热与光声探测技术的基本原理,结合光学薄膜的吸收测试、光学薄膜的激光辐照特性表征、激光损伤特性表征以及光学薄膜的机械性质表征等各种具体应用,对激光量热法、光热偏转法、表面声波法等典型的光热、光声检测方法进行了分析;阐述了这些方法的测试原理以及各自优势与不足。介绍了该领域利用这些方法取得的一些成果,并就光声光热检测技术的发展趋势做了展望。     

Hamilton formalism and variational principle construction

It is widely accepted that a variational principle cannot be constructed for an arbitrary differential equation; a rigorous mathematical condition shows which equations can have a variational formulation. On the other hand, the importance for variational principles in various fields of physics resulted in several methods to circumvent this condition and to construct another type of variational principles for any differential equation. In this paper the common origin of the considered methods is investigated, and a generalized Hamiltonian formalism is formulated. Additionally, constructive algorithms are given by different methods to construct variational principles. Simple examples are presented to make construction methods more transparent: several Lagrangians are constructed for the different forms of the Maxwell equations and for the extended heat conduction equation.