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1.
We consider the integral functional
under non-standard growth assumptions that we call p(x) type: namely, we assume that
a relevant model case being the functional
Under sharp assumptions on the continuous function p(x)>1 we prove regularity of minimizers. Energies exhibiting this growth appear in several models from mathematical physics. Accepted July 13, 2000?Published online January 22, 2001  相似文献   

2.
In this paper, first a class of fractional differential equations are obtained by using the fractional variational principles. We find a fractional Lagrangian L(x(t), where a c D t α x(t)) and 0<α<1, such that the following is the corresponding Euler–Lagrange
(1)
At last, exact solutions for some Euler–Lagrange equations are presented. In particular, we consider the following equations
(2)
(3)
where g(t) and f(t) are suitable functions. D. Baleanu is on leave of absence from Institute of Space Sciences, P.O. BOX MG-23, 76900 Magurele-Bucharest, Romania. e-mail: baleanu@venus.nipne.ro.  相似文献   

3.
1IntroductionandPreliminariesLetXbearealBanachspacewithnormIJ'11andadualX'.ThenormalizeddualitymappingJ:X~ZxisdefinedbyJx={x'eX*I(x,x')=11x112=11x if'},where',')denotesthegeneralizeddualitypairing.Itiswell-knownthatifX isstrictlyconvex,Jissingle-valuedandJ(tx)=tjxforallt201xeX.IfX*isuniformlyconvex,thenJisuniformlycontinuousonanyboundedsubsetSofX(of.Browde,fljandBarbuL2]).AnoperatorTwithdomainD(T)andrangeR(T)inXissaidtobeaccretiveifforeveryx,y6D(T),thereexistsajeJ(x--y)suchthat(T…  相似文献   

4.
Let be the exterior of the closed unit ball. Consider the self-similar Euler system
Setting α = β = 1/2 gives the limiting case of Leray’s self-similar Navier–Stokes equations. Assuming smoothness and smallness of the boundary data on ∂Ω, we prove that this system has a unique solution , vanishing at infinity, precisely
The self-similarity transformation is v(x, t) = u(y)/(t* − t)α, y = x/(t* − t)β, where v(x, t) is a solution to the Euler equations. The existence of smooth function u(y) implies that the solution v(x, t) blows up at (x*, t*), x* = 0, t* < + ∞. This isolated singularity has bounded energy with unbounded L 2 − norm of curl v.  相似文献   

5.
The divergence identity for punctured domain B1(0)\ {0}
suggest a viewpoint on describing the behavior of a function uC2(B1(0)\{0}) near the origin. This is useful especially on describing the singular behavior of solutions of polyharmonic equations. In this paper we mainly show that the solution u of the equation
satisfies the identity that, letting vi=(–)iu
provided there exist s0>0 and t0 0 such that f(x,t) c|x|tq for 0<|x|<s0 and t t0 with nq(n–2p) and q>1.Dedicated to Professor Shui-Nee Chow on the occasion of his 60th birthday.  相似文献   

6.
We investigate the asymptotic behavior of solutions of the damped nonlinear oscillator equation
where uf(u) > 0 for u ≠ 0, a(t) ≥ 0, and α is a positive constant with 0 < α ≥ 1. The case α = 1 has been investigated by a number of other authors. Here, it is shown that the behavior of solutions in the case of sublinear damping (0 < α < 1) is completely different from that in the case of linear damping (α = 1). Sufficient conditions for all nonoscillatory solutions to converge to zero and sufficient conditions for the existence of a nonoscillatory solution that does not converge to zero are given. We also give sufficient conditions for all solutions to be nonoscillatory. Some open problems for future research are also indicated. __________ Published in Neliniini Kolyvannya, Vol. 8, No. 2, pp. 186–200, April–June, 2005.  相似文献   

7.
The Aronsson-Euler equation for the functional
on W g 1, ∞(Ω, ℝ m , i.e., W 1, ∞ with boundary data g, is
This equation has been derived for smooth absolute minimizers, i.e., a function which minimizes F on every subdomain. We prove in this paper that for m=1, n≧ 1, or n=1, m≧ 1 an absolute minimizer of F exists in W g 1, ∞(Ω, ℝ m and for m= 1, n≧ 1 any absolute minimizer of F must be a viscosity solution of the Aronsson-Euler equation. Accepted November 13, 2000?Published online April 23, 2001  相似文献   

8.
We establish efficient conditions guaranteeing that every solution of the problem
u¢(t) 3 l(u)(t),    u(a) 3 h(u), u'(t) \geq \ell (u)(t),\quad u(a) \geq h(u),  相似文献   

9.
Let X be a uniformly smooth real Banach space. Let T:X → X be continuos and strongly accretive operator. For a given f ε X, define S: X → X by Sx =f−Tx+x, for all x ε X. Let {an} n=0 , {βn} n=0 be two real sequences in (0, 1) satisfying:
((i))
;
((ii))
Assume that {un} n=0 and {υn} n=0 are two sequences in X satisfying ‖un‖ = 0(αn) and ‖υn‖ → 0 as n → ∞. For arbitrary x0 ε X, the iteration sequence {xn} is defined by
(1)
Moreover, suppose that {Sxn} and {Syn} are bounded, then {xn} converges strongly to the unique fixed point of S.  相似文献   

10.
We study the stationary Dirac equation
where M(x) is a matrix potential describing the external field, and R(x, u) stands for an asymptotically quadratic nonlinearity modeling various types of interaction without any periodicity assumption. For ħ fixed our discussion includes the Coulomb potential as a special case, and for the semiclassical situation (ħ → 0), we handle the scalar fields. We obtain existence and multiplicity results of stationary solutions via critical point theory.  相似文献   

11.
This paper addresses the phenomenon of spinodal decomposition for the Cahn-Hilliard equation
where Ω⊂ℝ n , n∈{1,2,3 }, is a bounded domain with sufficiently smooth boundary, and f is cubic-like, for example f(u) =uu 3. Based on the results of [26] the nonlinear Cahn-Hilliard equation will be discussed. This equation generates a nonlinear semiflow in certain affine subspaces of H 2(Ω). In a neighborhood U ε with size proportional to ε n around the constant solution , where μ lies in the spinodal region, we observe the following behavior. Within a local inertial manifold containing there exists a finite-dimensional invariant manifold which dominates the behavior of all solutions starting with initial conditions from a small ball around with probability almost 1. The dimension of is proportional to ε n and the elements of exhibit a common geometric quantity which is strongly related to a characteristic wavelength proportional to ε. (Accepted May 25, 1999)  相似文献   

12.
We consider the Cauchy problem for a strictly hyperbolic, N × N quasilinear system in one-space dimension
where , is a smooth matrix-valued map and the initial data is assumed to have small total variation. We present a front tracking algorithm that generates piecewise constant approximate solutions converging in to the vanishing viscosity solution of (1), which, by the results in [6], is the unique limit of solutions to the (artificial) viscous parabolic approximation
as . In the conservative case where A(u) is the Jacobian matrix of some flux function F(u) with values in , the limit of front tracking approximations provides a weak solution of the system of conservation laws u t + F(u) x = 0, satisfying the Liu admissibility conditions. These results are achieved under the only assumption of strict hyperbolicity of the matrices A(u), . In particular, our construction applies to general, strictly hyperbolic systems of conservation laws with characteristic fields that do not satisfy the standard conditions of genuine nonlinearity or of linear degeneracy in the sense of Lax[17], or in the generalized sense of Liu[23]. Dedicated to Prof. Tai Ping Liu on the occasion of his 60 th birthday  相似文献   

13.
We develop the axisymmetric Synthetic Schlieren technique to study the wake of a microscale sphere settling through a density stratification. A video-microscope was used to magnify and image apparent displacements of a micron-sized random-dot pattern. Due to the nature of the wake, density gradient perturbations in the horizontal greatly exceed those in the vertical, requiring modification of previously developed axisymmetric techniques. We present results for 780 and 383 μm spheres, and describe the limiting role of noise in the system for a 157 μm sphere. This technique can be instrumental in understanding a range of ecological and environmental oceanic processes on the microscale.
King-Yeung Yick (Corresponding author)Email:
Roman StockerEmail:
Thomas PeacockEmail:
  相似文献   

14.
Two- and three-dimensional flows in nearly cuboidal cavities are investigated experimentally. A tight cavity is formed in the gap between two long and parallel cylinders of large radii by adding rigid top, bottom, and end walls. The cross-section perpendicular to the axes of the cylinders is nearly rectangular with aspect ratio Γ. The axial aspect ratio Λ > 10 is large to suppress end-wall effects. The fluid motion is driven by independent and steady rotation of the cylinders about their axes which defines two Reynolds numbers Re 1,2. Stability boundaries of the nearly two-dimensional steady flow have been determined as functions of Re 1,2 for Γ = 0.76 and Γ = 1. Up to six different three-dimensional supercritical modes have been identified. The critical thresholds for the onset of most of the three-dimensional modes, three of which have been observed for the first time, agree well with corresponding linear-stability calculations. Particular attention is paid to the flow for Γ = 1 under symmetric and parallel wall motion. In that case the basic flow consists of two mirror symmetric counter-rotating parallel vortices. They become modulated in span-wise direction as the driving increases. Detailed LDV measurements of the supercritical three-dimensional velocity field and the bifurcation show an excellent agreement with numerical simulations.
Tanja Siegmann-Hegerfeld (Corresponding author)Email:
Stefan AlbensoederEmail:
Hendrik C. KuhlmannEmail:
  相似文献   

15.
Let E be a Banach space. We prove the instability of the trivial solution of the differential equation
where f: [0, +∞) × E → ℝ is a continuous mapping for which
__________ Translated from Neliniini Kolyvannya, Vol. 8, No. 3, pp. 404–414, July–September, 2005.  相似文献   

16.
An iterative procedure, based on the proper orthogonal decomposition (POD), first proposed by Everson and Sirovich (J Opt Soc Am A 12(8):1657–1664, 1995) is applied to marred particle image velocimetry (PIV) data of shallow rectangular cavity flow at Mach 0.19, 0.28, 0.38, and 0.55. The procedure estimates the POD modes while simultaneously estimating the missing vectors in the PIV data. The results demonstrate that the absolute difference between the repaired vectors and the original PIV data approaches the experimental uncertainty as the number of included POD modes is increased. The estimation of the dominant POD modes is also shown to converge by examining the subspace spanned by the POD eigenfunctions.
Nathan E. Murray (Corresponding author)Email:
Lawrence S. UkeileyEmail:
  相似文献   

17.
This paper is devoted to time-global solutions of the Fisher-KPP equation in ℝ N :
where f is a C 2 concave function on [0,1] such that f(0)=f(1)=0 and f>0 on (0,1). It is well known that this equation admits a finite-dimensional manifold of planar travelling-fronts solutions. By considering the mixing of any density of travelling fronts, we prove the existence of an infinite-dimensional manifold of solutions. In particular, there are infinite-dimensional manifolds of (nonplanar) travelling fronts and radial solutions. Furthermore, up to an additional assumption, a given solution u can be represented in terms of such a mixing of travelling fronts. Accepted October 30, 2000?Published online March 21, 2001  相似文献   

18.
This paper reports laser-Doppler measurements of the mean flow and turbulence stresses in a swirling pipe flow. Experiments were carried out under well-controlled laboratory conditions in a refractive index-matched pipe flow facility. The results show pronounced asymmetry in mean and fluctuating quantities during the downstream decay of the swirl. Experimental data reveal that the swirl significantly modifies the anisotropy of turbulence and that it can induce explosive growth of the turbulent kinetic energy during its decay. Anisotropy invariant mapping of the turbulent stresses shows that the additional flow deformation imposed by initially strong swirling motion forces turbulence in the core region to tend towards the isotropic two-component state. When turbulence reaches this limiting state it induces rapid production of turbulent kinetic energy during the swirl decay.
J. Jovanović (Corresponding author)Email:
F. DurstEmail:
  相似文献   

19.
Consider the Cauchy problem for a strictly hyperbolic, N × N quasilinear system in one space dimension
ut  +  A(u)ux = 0,        u(0, x) = [`(u)](x),                 (1)u_{t} \, + \, A(u)u_{x} = 0, \qquad u(0, x) = {\bar u}(x), \quad \quad \quad \quad (1)  相似文献   

20.
The existence and uniqueness of a solution to the nonstationary Navier–Stokes system having a prescribed flux in an infinite cylinder is proved. We assume that the initial data and the external forces do not depend on x3 and find the solution (u, p) having the following form
where x′  =  (x1, x2). Such solution generalize the nonstationary Poiseuille solutions.  相似文献   

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