Criteria for the existence of solutions to random integral and differential equations

In [1], we proved a general rondom fixed point theorem and gave some applications. In this paper, we shall give further applications of the theorem. We first obtain a rondom Darbo’s fixed point theorem, using the theorem, we give the criteria for the existence of solutions under compactness hypotheses to nonlinear rondom volterra integral equations and the Cauchy problem of nonlinear rondom differential equations. Our theorems improve andgeneralize some main results of Lakshmikanthem^[2], Vaughn^[3,4] as well as De Blasi and Myjak^[5].     

分数阶微分方程的Haar小波算法研究

在BPFs的Caputo分数阶微分算子矩阵的基础上,建立了Haar小波的分数阶微分算子矩阵,提出了一种有效的求解分数阶微分方程的Haar小波数值方法,并将该方法应用于线性和非线性分数阶常微分方程求解中.数值算例表明,该算法简单,数值精确度高,是一种高效的数值求解方法.     

Stability analysis of linear fractional differential system with multiple time delays

In this paper, we study the stability of n-dimensional linear fractional differential equation with time delays, where the delay matrix is defined in (R ⁺)^n×n. By using the Laplace transform, we introduce a characteristic equation for the above system with multiple time delays. We discover that if all roots of the characteristic equation have negative parts, then the equilibrium of the above linear system with fractional order is Lyapunov globally asymptotical stable if the equilibrium exist that is almost the same as that of classical differential equations. As its an application, we apply our theorem to the delayed system in one spatial dimension studied by Chen and Moore [Nonlinear Dynamics 29, 2002, 191] and determine the asymptotically stable region of the system. We also deal with synchronization between the coupled Duffing oscillators with time delays by the linear feedback control method and the aid of our theorem, where the domain of the control-synchronization parameters is determined.     

General solutions to a class of time fractional partial differential equations

A class of time fractional partial differential equations is considered, which in- cludes a time fractional diffusion equation, a time fractional reaction-diffusion equation, a time fractional advection-diffusion equation, and their corresponding integer-order partial differential equations. The fundamental solutions to the Cauchy problem in a whole-space domain and the signaling problem in a half-space domain are obtained by using Fourier- Laplace transforms and their inverse transforms. The appropriate structures of the Green functions are provided. On the other hand, the solutions in the form of a series to the initial and boundary value problems in a bounded-space domain are derived by the sine- Laplace or cosine-Laplace transforms. Two examples are presented to show applications of the present technique.     

分数阶黏弹性土层中分数阶三维轴对称桩的竖向振动

将桩基和土体视为三维连续介质,桩基和土体的应力一应变关系采用分数阶黏弹性模型描述。在三维轴对称情况下,利用三维弹性理论和连续介质力学理论,运用分离变量法和分数阶导数的性质,得到了分数阶黏弹性土层中分数阶黏弹性桩基的三维轴对称解;并分析了相关参数对桩顸动态刚度和等效阻尼的影响。研究结果表明：与土体相比,桩基的相关参量对桩顶复刚度的影响较大;桩基和土体的密度比、模量比对桩顶复刚度都有较大的影响。     

Refined differential equations of deflections in axial symmetrical bending problems of spherical shell and their singular perturbation solutions

This paper deals with the research of accuracy of differential equations of deflections.The basic idea is as follows.Firstly,considering the boundary effect the meridianmidsurface displacement u=0,thus we derive the deflection differential equations;secondly we accurately prove that by use of the deflection differential equations or theoriginal differential equations the same inner forces solutions are obtained;finally,weaccurately prove that considering the boundary effect the meridian surface displacementu=0 is an exact solution.In this paper we give the singular perturbation solution of thedeflection differential equations.Finally we check the equilibrium condition and prove theinner forces solved by perturbation method and the outer load are fully equilibrated.Itshows that perturbation solution is accurate.On the other hand,it shows again that thedeflection differential equation is an exact equation.The features of the new differential equations are as follows:1.The accuracies of the new differentia     

STUDYING THE FOCAL VALUE OF ORDINARY DIFFERENTIAL EQUATIONS BY NORMAL FORM THEORY

ＳＴＵＤＹＩＮＧＴＨＥＦＯＣＡＬＶＡＬＵＥＯＦＯＲＤＩＮＡＲＹＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＢＹＮＯＲＭＡＬＦＯＲＭＴＨＥＯＲＹＺｈａｎｇＱｉｃｈａｎｇ（张琪昌）（ＴｉａｎｊｉｎＵｎｉｖｅｒｓｉｔｙ．Ｔｉａｎｊｉｎ３０００７２．Ｐ．Ｒ．Ｃ...     

Plane surface suddenly set in motion in a viscoelastic fluid with fractional Maxwell model

The fractional calculus approach in the constitutive relationship model of viscoelastic fluid is introduced. The flow near a wall suddenly set in motion is studied for a non-Newtonian viscoelastic fluid with the fractional Maxwell model. Exact solutions of velocity and stress are obtained by using the discrete inverse Laplace transform of the sequential fractional derivatives. It is found that the effect of the fractional orders in the constitutive relationship on the flow field is significant. The results show that for small times there are appreciable viscoelastic effects on the shear stress at the plate, for large times the viscoelastic effects become weak. The project supported by the National Natural Science Foundation of China (10002003), Foundation for University Key Teacher by the Ministry of Education, Research Fund for the Doctoral Program of Higher Education     

On the definition of fractional derivatives in rheology

During the last two decades fractional calculus has been increasingly applied to physics, especially to rheology. It is well known that there are obivious differences between Riemann-Liouville (R-L) definition and Caputo definition, which are the two most commonly used definitions of fractional derivatives. The multiple definitions of fractional derivatives have hindered the application of fractional calculus in rheology. In this paper, we clarify that the R-L definition and Caputo definition are both rheologically unreasonable with the help of the mechanical analogues of the fractional element model. We also find that to make them more reasonable rheologically, the lower terminals of both definitions should be put to ?∞. We further prove that the R-L definition with lower terminal ?∞ and the Caputo definition with lower terminal ?∞ are equivalent in the differentiation of functions that are smooth enough and functions that have finite number of singular points. Thus we can define the fractional derivatives in rheology as the R-L derivatives with lower terminal ?∞ (or, equivalently, the Caputo derivatives with lower terminal ?∞ ) not only for steady-state processes, but also for transient processes.     

二维柱坐标系中守恒的保球对称的中心型拉氏方法

提出了一种Godunov型中心型拉氏方法,用于求解二维柱坐标系中的可压缩多介质Euler方程组,该方法完全在体积控制体上离散,不仅保证质量、动量和总能量守恒,且该方法在二维柱坐标系中保一维球对称;并且对一维球对称问题在球对称网格划分下,精度测试表明该方法具有一阶精度,算例显示方法非常有效。     

Dynamic behavior of fractional order Duffing chaotic system and its synchronization via singly active control

With the increasingly deep studies in physics and technology,the dynamics of fractional order nonlinear systems and the synchronization of fractional order chaotic systems have become the focus in scientific research.In this paper,the dynamic behavior including the chaotic properties of fractional order Duffing systems is extensively investigated.With the stability criterion of linear fractional systems,the synchronization of a fractional non-autonomous system is obtained.Specifically,an effective singly active control is proposed and used to synchronize a fractional order Duffing system.The numerical results demonstrate the effectiveness of the proposed methods.     

Measurement of curved-surface deformation in cylindrical coordinates

Stereo vision is used to measure the strain field of a round tension test specimen in a cylindrical coordinate system. Initially, the displacement fields of the specimen are measured relative to a world coordinate system erected by the stereo vision. Through coordinate transformations, the measured displacement fields expressed in world coordinates are then converted to the displacement fields expressed in cylindrical coordinates. By differentiating the axial and circumferential displacements in the axial and circumferential directions, the axial, circumferential and shear strains are determined. Results indicate that the measured mean value of the axial strains is in good agreement with the measurements of the extensometer and the strain gage. The Poisson's ratio obtained by the circumferential and axial strains is close to .33 in the elastic state. The mean error of the computed shear strain is approximately .03 percent in the smaller elastic deformation and .08 percent in the larger plastic deformation.     

岩石流变分数阶模型研究

以Kelvin流变模型为研究对象,提出了一种分数阶Kelvin流变模型。首先,把Kelvin模型中的整数阶导数改为分数阶导数,考虑到岩石材料的频率通常不超过1000 Hz,在分数阶拟合时,拟合频段选取为[0 1000],进而利用Oustalop滤波算法把分数阶表示为整数阶模式;其次,利用试验数据对分数阶模型进行参数识别,考虑到分数阶Kelvin模型具有强非线性的特点,引入了Levenberg-Marquardt优化算法来确定未知参数;最后,对于频域表示的流变方程,利用Laplace逆变换获得流变精确表达式。仿真实例表明本文方法可以很好地反映岩石流变特性。     

Construction space harmonic functions in polynomial form and spherical functions by complex-functional

In this paper, applying the theory of complex-functional, not only the space harmonic functions in polynomial form, but also the spherical functions are obtained.     

The fractional dimension identification method of critical bifurcated parameters of bearing-rotor system

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Electromagnetohydrodynamic (EMHD) flow of fractional viscoelastic fluids in a microchannel

This study investigates the electromagnetohydrodynamic (EMHD) flow of fractional viscoelastic fluids through a microchannel under the Navier slip boundary condition. The flow is driven by the pressure gradient and electromagnetic force where the electric field is applied horizontally, and the magnetic field is vertically (upward or downward). When the electric field direction is consistent with the pressure gradient direction, the changes of the steady flow rate and velocity with the Hartmann number Ha are irrelevant to the direction of the magnetic field (upward or downward). The steady flow rate decreases monotonically to zero with the increase in Ha. In contrast, when the direction of the electric field differs from the pressure gradient direction, the flow behavior depends on the direction of the magnetic field, i.e., symmetry breaking occurs. Specifically, when the magnetic field is vertically upward, the steady flow rate increases first and then decreases with Ha. When the magnetic field is reversed, the steady flow rate first reduces to zero as Ha increases from zero. As Ha continues to increase, the steady flow rate (velocity) increases in the opposite direction and then decreases, and finally drops to zero for larger Ha. The increase in the fractional calculus parameter α or Deborah number De makes it take longer for the flow rate (velocity) to reach the steady state. In addition, the increase in the strength of the magnetic field or electric field, or in the pressure gradient tends to accelerate the slip velocity at the walls. On the other hand, the increase in the thickness of the electric double-layer tends to reduce it.

     

Superposition about the 3D vortex solutions of the fluid dynamic equation

ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｌ＿ｋｎｏｗｎｔｈａｔｓｏｍｅｎｏｎｌｉｎｅａｒｄｙｎａｍｉｃｅｑｕａｔｉｏｎｓ,ｓｕｃｈａｓＫｄＶｅｑｕａｔｉｏｎ ,ｓｉｎｅ＿Ｇｏｒｄｅｎｅｑｕａｔｉｏｎ ,ｈａｖｅｅｘａｃｔｓｏｌｉｔｏｎｓｏｌｕｔｉｏｎｓ.Ａｖｅｒｙｉｍｐｏｒｔａｎｔｓｐｅｃｉａｌｉｔｙｏｆｔｈｅｓｏｌｉｔｏｎｓｏｌｕｔｉｏｎｓｏｆｎｏｎｌｉｎｅａｒｅｑｕａｔｉｏｎｓｉｓｔｈａｔｔｈｅｙｍａｙｈａｖｅａｓｕｐｅｒｐｏｓｉｔｉｏｎ ,ｉ.ｅ .,ｔｈｅｓｅｎｏｎｌｉｎｅａｒｅｑｕａｔｉｏｎｓｍａｙ…     

Role of Prehistories in the Initial Value Problems of Fractional Viscoelastic Equations

The fractional viscoelastic equation (FVE), which is a second-order differential equation with fractional derivatives describing the dynamical behavior of a single-degree-of-freedom viscoelastic oscillator, is considered. Some viscoelastic damped mechanical systems may be described by FVEs. However, FVEs with conventional nonzero initial values cannot generally be solved. In this paper, the prehistories of the unknown functions before the initial times, referred to as the initial functions, are taken into account to solve FVEs. Mathematically, appropriate initial functions are essential for unique solutions of FVEs. Physically, the initial functions reflect the processes of giving the initial values. FVEs are solved for some initial functions both by analytical and numerical methods. The initial functions affect the solutions of FVEs. It is discussed how the solutions depend on the initial functions. Implication of the solutions to viscoelastic materials will be discussed.     

分数算子描述的黏弹性体力学问题数值方法

讨论由黎曼-刘维尔 (Riemann-Liouville)分数导数描述的黏弹性体力学问题的数 值方法. 该方法利用黎曼-刘维尔分数 导数定义中核函数的特性，并结合被积函数在单步中的逼近以及Newmark型数值法，建立 了分数导数计算公式. 算例表明，该算法具有收敛快、精度高、稳定性好和易于 应用和改进的优点. 在对动态系统的瞬态响应分析和有限元分析格式中，算法都获得了 满意的结果.