ON THE PROBLEMS OF PREVENTING THE BLOWING UP OF THE SOLUTIONS FOR SEMILINEAR PARABOLIC EQUATIONS

§ 1 Introduction The investigating of the existence of globally smooth solutions or the formation of singularities of the solutions for semilinear parabolic equations is of much importance in the theory of partial differential equation as well as in the application. The blowing up of the solutions is an interesting phenomenon and has been pointed out by many authors in various cases, such as by S. Kaplan [1], C. V. pao[2], H. Kawarada[3]etc. In[4], Chen studied the problem of     

NONLINEAR OPERATOR APPROXIMATION THEORY BASED ON DEMI-REGULAR CONVERGENCE

§1.Introduction Regular operator approximation therory,developed in[3]and[4],pertains to nonlinear operators with certain inverse compactness ptoperties The results give the seistence of solutions of equations and the convergence of approximate     

GLOBAL REGULARITY FOR MODIFIED CRITICAL DISSIPATIVE QUASI-GEOSTROPHIC EQUATIONS

We consider the n-dimensional modified quasi-geostrophic(SQG) equations δ_tθ + u·▽θ+kΛαθ=0, u = Λα-1R⊥θ with κ 0, α∈(0, 1] and θ0∈ W1,∞(Rn). In this paper, we establish a different proof for the global regularity of this system. The original proof was given by Constantin, Iyer, and Wu[5], who employed the approach of Besov space techniques to study the global existence and regularity of strong solutions to modified critical SQG equations for two dimensional case.The proof provided in this paper is based on the nonlinear maximum principle as well as the approach in Constantin and Vicol [2].     

Superconvergence of Finite Element Approximations to Parabolic and Hyperbolic Integro-Differential Equations

1 IntroductionRecently, considerable attention has been devoted to the finite element analysis fOr par-tiaJ illtegro-differential equations, see, fOr example, Yanik and Ftweatherl1], Cannon andLin[2'3] 5 Chen and Shih[4], Lin, Thomee and Wahlbi.I5l ? Thomee and Zhang[6] and ZhangI7j8J.The main tool used for this kind of equations is the mtz-Voterra projection [5'7] as againstttitz projection fOr parabolic equation. In this paPer, we are concerned primarily with theanalysis of knot supe…     

Existence of Periodic Solutions to a Class of Third-order p-Laplacian Equations with Delays

By using the continuation theorem of coincidence degree theory due to Mawhin and the new analytical method, we study the T-periodic solutions to a class of third order p-Laplacian equations with distributed delays as follows . Some new results for existence of T-periodic solutions to such equations are obtained.     

SOME FURTHER NOTES ON THE MATRIX EQUATIONS A~TXB+B~TX~TA=C AND A~TXB+B~TXA=C

Dehghan and Hajarian, [4], investigated the matrix equations ATXB +BTXTA =C and ATXB + BTXA = C providing inequalities for the determinant of the solutions of these equations. In the same paper, the authors presented a lower bound for the product of the eigenvalues of the solutions to these matrix equations. Inspired by their work, we give some generalizations of Dehghan and Hajarian results. Using the theory of the numerical ranges, we present an inequality involving the trace of C when A, B, X are normal matrices satisfying ATB = BAT.     

THE VANISHING PRESSURE LIMIT OF SOLUTIONS TO THE SIMPLIFIED EULER EQUATIONS FOR ISENTROPIC FLUIDS

In this paper,the Riemann problem of the 1-D reduced model for the 2-D Euler equations is considered and the Riemann solutions are obtained.It is proved that,as the pressure vanishes,they converge to two kinds of Riemann solutions to the 1D reduced model for the 2-D transport equations:one contains δ-shocks,the other contains vacuum.     

A refined invariant subspace method and applications to evolution equations

The invariant subspace method is refined to present more unity and more diversity of exact solutions to evolution equations.The key idea is to take subspaces of solutions to linear ordinary differential equations as invariant subspaces that evolution equations admit.A two-component nonlinear system of dissipative equations is analyzed to shed light on the resulting theory,and two concrete examples are given to find invariant subspaces associated with 2nd-order and 3rd-order linear ordinary differential equations and their corresponding exact solutions with generalized separated variables.     

LARGE TIME STEP GENERALIZATIONS OF GLIMM''''S SCHEME FOR SYSTEMS OF CONSERVATION LAWS

Two kinds of generalizations of Glimm's scheme for Courant numbers larger than1/2 is introduced. For one kind of the generalizations, referred to as L. T. S. Glimm's scheme(I), it is shown that for any fixed (but arbitrary large) Courant number if a sequence ofapproximate solutions converges to a limit u as the mesh is refined, then u is a werk solutionto the system of conservation laws/for almost choise of random sequence. Furthermore it is,obtained that for scalar equations and systems of conservation laws the family ofapproximate solutions contains convergent subsequnce. For another kind of generalizations with any fixed (but arbitrary large) Courantnumber, referred to as L. T. S. Glhnm's scheme (Ⅱ), it is proved that the family ofapproximate solutions to the system of isothermal gas dynamics equations contains aconvergent subsequence provided the total varigtion of the initial data is bounded.     

Multi-valued variational inequalities with K-pseudomonotone operators

In this paper, we first employ the 1961 celebrated Fan lemma to derive a very general existence result for multi-valued variational inequalities involving multi-valued K-pseudomonotone operators. It will be seen that this result improves and unifies existence results of variational inequalities for monotone operators. Next, we establish some uniqueness results for multi-valued variational inequalities by introducing the concepts of strict, , and strong K-pseudomonotonicity of multi-valued operators, respectively. These uniqueness results appear to be new even if the underlying space is finite-dimensional.This work was partially supported by the National Science Council Grant NSC 82-0208-M-110-023. The author would like to express his sincere thanks to the referees for their valuable comments and suggestions that improved this paper substantially.     

Elasto-plastic contact problems with heat exchange

This paper deals with a dynamical model for the motion of a one-dimensional visco-elasto-plastic body in contact with an elasto-plastic obstacle and undergoing thermal expansion. The problem for the unknown displacement and temperature is rewritten in accordance with the formalism of hysteresis operators as solution operators of the underlying variational inequalities. The system consists of the momentum balance and energy balance equations. The existence result for this thermodynamically consistent problem is obtained by using some a priori estimates established for the space discretized problem while the uniqueness result follows from the Lipschitz continuity of the nonlinearities.     

Generalized Vector Variational Inequalities

In this paper, we introduce a generalized vector variational inequality problem (GVVIP) which extends and unifies vector variational inequalities as well as classical variational inequalities in the literature. The concepts of generalized C-pseudomonotone and generalized hemicontinuous operators are introduced. Some existence results for GVVIP are obtained with the assumptions of generalized C-pseudomonotonicity and generalized hemicontinuity. These results appear to be new and interesting. New existence results of the classical variational inequality are also obtained.     

Existence of Solutions for Generalized Vector Variational-like Inequalities

In this paper, we consider a generalized vector variational-like inequality problem (for short, GVVLIP), which includes generalized vector variational inequalities, vector variational inequalities and classical variational inequalities as special cases. The concepts of generalized C-pseudomonotone-like and generalized H-hemicontinuous-like operators are introduced. Some existence results for GVVLIP are obtained under the assumptions of generalized C-pseudomonotone-like property and generalized H-hemicontinuous-like property. These results appear to be new and interesting. New existence results of the classical variational inequality are also obtained. In this research, the first author was partially supported by the Teaching and Research Award Fund for Outstanding Young Teachers in Higher Education Institutions of MOE, China and the Dawn Program Foundation in Shanghai. The third author was partially supported by Grant NSC 94-2213-E-110-035.     

Non-compact generalized variational inequalities for quasi-monotone and hemi-continuous operators with applications

Some results are obtained for non-compact cases in topological vector spaces for the existence problem of solutions for some set-valued variational inequalities with quasi-monotone and lower hemi-continuous operators, and with quasi-semi-monotone and upper hemi-continuous operators. Some applications are given in non-reflexive Banach spaces for these existence problems of solutions and for perturbation problems for these set-valued variational inequalities with quasi-monotone and quasi-semi-monotone operators. This revised version was published online in June 2006 with corrections to the Cover Date.     

Convergence analysis of non-quadratic proximal methods for variational inequalities in Hilbert spaces

We consider a general approach for the convergence analysis of proximal-like methods for solving variational inequalities with maximal monotone operators in a Hilbert space. It proves to be that the conditions on the choice of a non-quadratic distance functional depend on the geometrical properties of the operator in the variational inequality, and –- in particular –- a standard assumption on the strict convexity of the kernel of the distance functional can be weakened if this operator possesses a certain `reserve of monotonicity'. A successive approximation of the `feasible set' is performed, and the arising auxiliary problems are solved approximately. Weak convergence of the proximal iterates to a solution of the original problem is proved.     

Projection-proximal methods for general variational inequalities

In this paper, we consider and analyze some new projection-proximal methods for solving general variational inequalities. The modified methods converge for pseudomonotone operators which is a weaker condition than monotonicity. The proposed methods include several new and known methods as special cases. Our results can be considered as a novel and important extension of the previously known results. Since the general variational inequalities include the quasi-variational inequalities and implicit complementarity problems as special cases, results proved in this paper continue to hold for these problems.     

On vector variational inequalities

In this paper, we study vector variational inequalities. The concept of weaklyC-pseudomonotone operator is introduced. By employing the Fan lemma, we establish several existence results. The new results extend and unify existence results of vector variational inequalities for monotone operators under a Banach space setting. In particular, existence results for the generalized vector complementarity problem with weaklyC-pseudomonotone operators in Banach space are obtained.This research was partially supported by the National Science Council of the Republic of China under Contract NSC 84-2121-M-110-008.     

Solutions to variational inequalities of parabolic type

The existence of strong solutions to a kind of variational inequality of parabolic type is investigated by the theory of semigroups of linear operators. As an application, an abstract semi permeable media problem is studied.     

Variational principle for the spectral exponent of polynomials of weighted composition operators

In this paper we derive a relationship between the Legendre-Fenchel transform of the spectral exponent of weighted composition operators acting in Lp-spaces and the Legendre-Fenchel transform obtained for their polynomials. We establish the variational principle for the spectral exponent of polynomials of weighted composition operators.