用VB和Matrix VB混合编程求解偏微分方程

对MatrixVB作了简单介绍,通过一个具体的例子演示了如何在VisualBasic6 0(以下简称VB)中调用MatrixVB的函数,将MATLAB的强大的计算功能与VB在图形用户界面(Windows界面)开发方面的优势结合起来,有效地解决了复杂的偏微分方程的求解问题。     

ON THE UNIMODALITY OF THE EXACT LIKELIHOOD FUNCTION FOR NORMAL AR(2) SERIES

Abstract. For stationary second-order autoregressive normal processes, the conjecture of uniqueness of the solution of the exact likelihood equations is examined. A sufficient condition for uniqueness is given; this condition is satisfied with very high probability if the number of observations is not extremely small. Moreover, it is shown that not more than two maxima may exist. Examples of data which actually produce a likelihood function with two local maxima are given.     

A continuous-time framework for least squares parameter estimation

This paper proposes a continuous-time framework for the least-squares parameter estimation method through evolution equations. Nonlinear systems in the standard state space representation that are linear in the unknown, constant parameters are investigated. Two estimators are studied. The first one consists of a linear evolution equation while the second one consists of an impulsive linear evolution equation. The paper discusses some theoretical aspects related to the proposed estimators: uniqueness of a solution and an attractive equilibrium point which solves for the unknown parameters. A deterministic framework for the estimation under noisy measurements is proposed using a Sobolev space with negative index to model the noise. The noise can be of large magnitude. Concrete signals issued from an electronic device are used to discuss numerical aspects.     

FracSym: Automated symbolic computation of Lie symmetries of fractional differential equations

In this paper, we present an algorithm for the systematic calculation of Lie point symmetries for fractional order differential equations (FDEs) using the method as described by Buckwar & Luchko (1998) and Gazizov, Kasatkin & Lukashchuk (2007, 2009, 2011). The method has been generalised here to allow for the determination of symmetries for FDEs with n$n$ independent variables and for systems of partial FDEs. The algorithm has been implemented in the new MAPLE package FracSym (Jefferson and Carminati 2013) which uses routines from the MAPLE symmetry packages DESOLVII (Vu, Jefferson and Carminati, 2012) and ASP (Jefferson and Carminati, 2013). We introduce FracSym by investigating the symmetries of a number of FDEs; specific forms of any arbitrary functions, which may extend the symmetry algebras, are also determined. For each of the FDEs discussed, selected invariant solutions are then presented.     

A conservative discontinuous Galerkin scheme for the 2D incompressible Navier–Stokes equations

In this paper we consider a conservative discretization of the two-dimensional incompressible Navier–Stokes equations. We propose an extension of Arakawa’s classical finite difference scheme for fluid flow in the vorticity–stream function formulation to a high order discontinuous Galerkin approximation. In addition, we show numerical simulations that demonstrate the accuracy of the scheme and verify the conservation properties, which are essential for long time integration. Furthermore, we discuss the massively parallel implementation on graphic processing units.     

Jet bundle formulation of infinite-dimensional port-Hamiltonian systems using differential operators

We consider infinite-dimensional port-Hamiltonian systems described on jet bundles. Based on a power balance relation we introduce the port-Hamiltonian system representation using differential operators regarding the structural mapping, the dissipation mapping and the input mapping. In contrast to the well-known representation on the basis of the underlying Stokes–Dirac structure our approach is not necessarily based on using energy-variables which leads to a different port-Hamiltonian representation of the analyzed partial differential equations. The presented constructions will be specialized to mechanical systems to which class also the presented examples belong.     

Psychophysical basis for maximum pushing and pulling forces: A review and recommendations

The objective of this paper was to perform a comprehensive review of psychophysically determined maximum acceptable pushing and pulling forces. Factors affecting pushing and pulling forces are identified and discussed. Recent studies show a significant decrease (compared to previous studies) in maximum acceptable forces for males but not for females when pushing and pulling on a treadmill. A comparison of pushing and pulling forces measured using a high inertia cart with those measured on a treadmill shows that the pushing and pulling forces using high inertia cart are higher for males but are about the same for females. It is concluded that the recommendations of Snook and Ciriello (1991) for pushing and pulling forces are still valid and provide reasonable recommendations for ergonomics practitioners. Regression equations as a function of handle height, frequency of exertion and pushing/pulling distance are provided to estimate maximum initial and sustained forces for pushing and pulling acceptable to 75% male and female workers.     

颗粒流体两相流基本方程中压差力和曳力系数的计算

本文总结了颗粒流体两相流基本方程的压差力表达方式和推导颗粒流体系统曳力系数计算公式的力平衡原理，提出了一种分析压差力的简单方法，阐明了各种压差力表达方式间的关系及对应的两相流基本方程的曳力系数的计算方法     

高热稳定性和可逆交联性质的含新型偶氮发色团电光聚合物的研究

制备了两种新型的分别含有以三苯胺为电子给体的偶氮类发色团作为特征活性官能团和3-呋喃甲酸及受保护的马来酰亚胺的可交联型聚合物体系．通过研究表明利用该制备方法，发色团在聚合物中的含量得到了极大的提高，分别达到32．1％（NLO1_P1）和44．4％（NLO1_P2）．该聚合物体系以“DielsAlder”[4＋2]环加成反应作为其交联特征，具有高温非交联、低温交联的特点，其过程与以往的热交联型聚合物相反，可解决传统电光交联聚合物中存在的热交联对极化效率影响的问题并用热失重分析法（TGA）和差示扫描量热法（DSC）分析了这一过程．此外DA交联型聚合物，不需要引入额外的助交联剂，克服了传统热交联聚合物分离难的问题，最大程度的保证了材料的纯度．