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In this paper, we consider a singular Adams' inequality with logarithmic weights in the unit ball of $ \mathbb {R}^4 $ R 4 . Our results extend the results of Zhu and Wang [Adams' inequality with logarithmic weights in $ \mathbb {R}^4 $ R 4 . Proc Amer Math Soc. 2021;149(8):3463–3472] on Adams' inequality with logarithmic weights to singular case. Then, we study the existence of solutions for some weighted mean field equations, relying on variational methods and the singular Adams' inequality with logarithmic weights we previously established. [ABSTRACT FROM AUTHOR]

In this paper, as an attempt we consider the linear self-interacting diffusion driven by an α-stable motion, which is the solution to the equation X t α = M t α − θ ∫ 0 t ∫ 0 s (X s α − X r α) d r d s + ν t , where θ ≠ 0 , ν ∈ R and M α is an α-stable motion on R ( 0 < α ≤ 2). The process is an analogue of the self-attracting diffusion (see Durrett-Rogers, Prob. Theory Related Fields92 (1992), 337–349, and Cranston-Le Jan, Math. Ann.303 (1995), 87–93.). The main object of this paper is to prove some limit theorems associated with the solution process X α for 1 2 < α ≤ 2. When θ > 0 we show that ψ α (t) (X t α − X ∞ α) converges to an α-stable random variable in distribution, as t tends to infinity, where ψ α (t) = t 1 / α for 1 ≤ α ≤ 2 and ψ α (t) = t 2 − 1 α for 1 2 < α < 1. When θ < 0 , for all 1 2 < α ≤ 2 we show that, as t → ∞ , J t α (θ , ν , 0) := t e 1 2 θ t 2 X t α converges to ξ ∞ α − ν θ and J t α (θ , ν , n) : = − θ t 2 (J t α (θ , ν , n − 1) − (2 n − 3) ! ! (ξ ∞ α − ν θ)) → (2 n − 1) ! ! (ξ ∞ α − ν θ) a.s. for all n ≥ 1 , where (− 1) ! ! = 1 and ξ ∞ α = ∫ 0 ∞ s e 1 2 θ s 2 d M s α . [ABSTRACT FROM AUTHOR]

This paper deals with the following mixed pseudo-parabolic p-Laplacian type equation with logarithmic nonlinearity u t − Δ u t − d i v (| ∇ u | p − 2 ∇ u) = | u | q − 2 u log ⁡ | u | in a bounded domain with zero Dirichlet boundary condition, which was studied in our previous paper [J Math Anal Appl. 2019;478(2):393-420]. In view the results of [J Math Anal Appl. 2019;478(2):393-420], for the case (1) 1 < p ≤ q ≤ 2 , i f n ≤ p , ≤ 2 , i f 2 n n + 2 < p < n , < n p n − p , i f p ≤ 2 n n + 2 , the global existence and blow-up results were got when J (u 0) ≤ d , where d denotes the mountain-pass level. But for the case (2) 1 < p ≤ q a n d 2 < q < ∞ , i f n ≤ p , n p n − p , i f 2 n n + 2 < p < n , the blow-up results were got when J (u 0) ≤ M , where M ≤ d is a constant. In this paper, we extend and complete the results of [J Math Anal Appl. 2019;478(2):393-420] on the following three aspects: First, the blow-up results are got when J (u 0) ≤ d and (2) are satisfied. Second, the upper and lower bounds of blow-up time are estimated. Third, the global existence and blow-up results are got when J (u 0) > d. [ABSTRACT FROM AUTHOR]

This paper presents asymptotic formulas in the case of the following two problems for the Pucci's extremal operators M ± . It is considered the solution u ε (x) of − ε 2 M ± ∇ 2 u ε + u ε = 0 in Ω such that u ε = 1 on Γ. Here, Ω ⊂ R N is a domain (not necessarily bounded) and Γ is its boundary. It is also considered v (x , t) the solution of v t − M ± ∇ 2 v = 0 in Ω × (0 , ∞) , v = 1 on Γ × (0 , ∞) and v = 0 on Ω × { 0 }. In the spirit of their previous works [Berti D, Magnanini R. Asymptotics for the resolvent equation associated to the game-theoretic p-laplacian. Appl Anal. 2019;98(10):1827–1842.; Berti D, Magnanini R. Short-time behavior for game-theoretic p-caloric functions. J Math Pures Appl (9). 2019;(126):249–272.], the authors establish the profiles as ϵ or t → 0 + of the values of u ε (x) and v (x , t) as well as of those of their q-means on balls touching Γ. The results represent a further step in the extensions of those obtained by Varadhan and by Magnanini-Sakaguchi in the linear regime. [ABSTRACT FROM AUTHOR]

In this paper, we study the long-time behavior of the chemotaxis-Navier–Stokes system ∂ t n + u ⋅ ∇ n = λ Δ n − ∇ ⋅ (χ (c) n ∇ c) , ∂ t c + u ⋅ ∇ c = μ Δ c − f (c) n , ∂ t u + u ⋅ ∇ u + ∇ P = ζ Δ u − n ∇ φ , ∇ ⋅ u = 0 , t > 0 , x ∈ Ω posed in a strip domain Ω := R 2 × [ 0 , 1 ] ⊂ R 3 . In Peng-Xiang (Math. Models Methods Appl. Sci., 28 (2018), 869-920), the authors have established the global existence of strong solutions to this system with non-flux boundary conditions for n and c and non-slip boundary conditions for u. Our main purpose is to establish the time-decay rates for such solutions. This will be done by using the anisotropic L p interpolation and the iterative techniques. [ABSTRACT FROM AUTHOR]

In this paper, we consider the following Choquard equation: − Δ u + u = (I α ∗ F (u)) F ′ (u) i n R N where N ⩾ 3 , α ∈ (0 , N) , I α is the Riesz potential, and F (u) := 1 p | u | p + 1 q | u | q , where p = N + α N and q = N + α N − 2 are lower and upper critical exponents in sense of the Hardy–Littlewood–Sobolev inequality. Based on perturbation method and the invariant sets of descending flow, we prove that the above equation possesses infinitely many sign-changing solutions. Our results extend the results in Seok [Nonlinear Choquard equations: doubly critical case. Appl Math Lett. 2018;76:148–156] and Su [New result for nonlinear Choquard equations: doubly critical case. Appl Math Lett. 2020;102(106092):0–7]. [ABSTRACT FROM AUTHOR]

In this paper, we study the evolution p, q-Laplacian equations u t = d i v (| ∇ u | p − 2 ∇ u) + u α ∫ Ω v m d x and v t = d i v (| ∇ v | q − 2 ∇ v) + v β ∫ Ω u n d x with 1 (p − 1 − α) (q − 1 − β) , there exist suitable initial data such that vanishing solutions exist. If m n < (p − 1 − α) (q − 1 − β) , we find the explicit scopes of initial data such that the solutions could not vanish, which complete the corresponding classifications of solutions in Math. Methods Appl. Sci. 39 (2016) 1325–1335 and Appl. Math. Comp. 259 (2015) 587–595, respectively. For the critical case m n = (p − 1 − α) (q − 1 − β) , the solutions vanish in finite time with small initial data. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the Hénon–Hardy type systems on R n : (− Δ) α 2 u (x) = | x | a v p (x) , u (x) ≥ 0 , x ∈ R n , (− Δ) α 2 v (x) = | x | b u q (x) , v (x) ≥ 0 , x ∈ R n , where n ≥ 2 , n > α , 0 < α ≤ 2 or α = 2 m. We prove Liouville theorems (i.e. non-existence of nontrivial nonnegative solutions) for the above Hénon–Hardy systems. The arguments used in our proof is the method of scaling spheres developed in [Dai W, Qin GLiouville type theorems for fractional and higher-order Hénon–Hardy type equations via the method of scaling spheres. preprint, submitted for publication, arXiv: 1810.02752.]. Our results generalize the Liouville theorems for single Hénon–Hardy equation on R n in Bidaut-Véron and Pohozaev [Nonexistence results and estimates for some nonlinear elliptic problems. J Anal Math. 2001;84:1.49], Chen et al. [Liouville type theorems, a priori estimates and existence of solutions for critical order Hardy–Hénon equations in R N . preprint, submitted, arXiv: 1808.06609], Dai et al. [Liouville type theorems, a priori estimates and existence of solutions for non-critical higher-order Lane–Emden–Hardy equations. preprint, submitted for publication, arXiv: 1808–10771], Dai and Qin [Liouville type theorems for Hardy–Hénon equations with concave nonlinearities. Math Nachrichten. 2020;293(6):1084–1093. ; Liouville type theorems for fractional and higher-order Hénon–Hardy type equations via the method of scaling spheres. preprint, submitted for publication, arXiv: 1810.02752], Guo and Liu [Liouville-type theorems for polyharmonic equations in R N and in Liouville-type theorems for. Proc Roy Soc Edinburgh Sect A. 2008;138(2):339–359], and Phan and Souplet [Liouville-type theorems and bounds of solutions of Hardy–Hénon equations. J Diff Equ. 2012;252:2544–2562] to systems. [ABSTRACT FROM AUTHOR]

Conjugate gradient methods are widely used for solving unconstrained optimization and nonlinear equations, specially in large-scale cases. Since they own the attractive practical factors of simple computation and low memory requirement, interesting theoretical features of curvature information and strong global convergence. In this paper, we present a modified conjugate gradient algorithm by line search method with acceleration scheme for nonlinear symmetric equations. Furthermore, the proposed method not only possess descent property but also owns global convergence in mild conditions. Numerical results also indicate that the presented method is much more effective than the other methods for the test problems. [ABSTRACT FROM PUBLISHER]

Some preconditioners for accelerating the classical iterative methods are given in Zhang et al. [Y. Zhang and T.Z. Huang, A class of optimal preconditioners and their applications, Proceedings of the Seventh International Conference on Matrix Theory and Its Applications in China, 2006. Y. Zhang, T.Z. Huang, and X.P. Liu, Modified iterative methods for nonnegative matrices and M-matrices linear systems, Comput. Math. Appl. 50 (2005), pp. 1587-1602. Y. Zhang, T.Z. Huang, X.P. Liu, A class of preconditioners based on the (I+S(α))-type preconditioning matrices for solving linear systems, Appl. Math. Comp. 189 (2007), pp. 1737-1748]. Another kind of preconditioners approximating the inverse of a symmetric positive definite matrix was given in Simons and Yao [G. Simons, Y. Yao, Approximating the inverse of a symmetric positive definite matrix, Linear Algebra Appl. 281 (1998), pp. 97-103]. Zhang et al. 's preconditioners and Simons and Yao's are generalized in this paper. These preconditioners are all of low construction cost, which all could be taken as approximate inverse of M-matrices. Numerical experiments of these preconditioners applied with Krylov subspace methods show the effectiveness and performance, which also show that the preconditioners proposed in this paper are better approximate inverse for M-matrices than Simons'. [ABSTRACT FROM AUTHOR]

Nonlinear systems of time dependent partial differential equations of real life phenomena tend to be very complicated to solve numerically. One common approach to solve such problems is by applying operator splitting which introduces subproblems that are easier to handle. The solutions of the subsystems are usually glued together by either the Godunov method (first-order) or the Strang method (second-order). However, the accuracy of such an approach may be very hard to analyse because of the complexity of the equations involved. The purpose of the present paper is to introduce another line of reasoning concerning the accuracy of operator splitting. Let us assume that a fully coupled and implicit discretization of the complete system has been developed. Under appropriate conditions on the continuous problem, such discretizations provide reasonable and convergent approximations. As in the continuous case, operator splitting can be utilized to obtain tractable algebraic subsystems. The problem we address in the present paper is to obtain a bound on the difference between the fully coupled implicit discrete solutions, uh, and the solutions, uh, s, obtained by applying operator splitting to these discrete equations. Suppose we know that uh converges to the analytical solution u as the grid is properly refined and, applying the results from this paper, that uh, s converges toward uh under grid refinement. Then, by the triangle inequality, also the splitting approximation uh, s converges toward the analytical solution u and convergence is thus obtained for an approximation that, from a practical point of view, is easier to compute. [ABSTRACT FROM AUTHOR]

In the literature, rank-constrained Hermitian nonnegative-definite solutions to the matrix equation AXAH=B have been investigated, under the conditions that B is Hermitian and nonnegative-definite, and the matrix equation is consistent. In this paper, we discuss rank-constrained Hermitian nonnegative-definite least squares solutions to this matrix equation, in which the above conditions may not hold. We derive the rank range and expression of these least squares solutions. Therefore, the results obtained in this paper generalize those in the literature. [ABSTRACT FROM AUTHOR]

The goal of this paper is to show some of the most important features of flying insects from a control point of view, describe in details the kinematics of insects during flapping flight, establish the corresponding kinematics equations of flying insects, analyze the force and moment acting on the flying insects, and establish the corresponding aerodynamic equations. Through the kinematics equations and aerodynamic equations of flying insects, the trajectory equations and attitude equations have also been established. A detailed mathematical model of flying insects is presented in this paper, which including 3 d.o.f. of wings kinematics, i.e., flapping, lagging and feathering, and 6 d.o.f. of insects body, i.e., yaw, roll, up–down flight, left–right flight and fore–back flight. All these motions of flying insects are interrelated by the kinematics equations, attitude equations, aerodynamics model and dynamics equations of the insects' centroid. In the findal part of this paper, the mathematical simulation model of flapping-wing insects is set up and the corresponding simulation curve created. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the convergence of finite element approximation to the exact solution of general self-adjoint elliptic equations with discontinuous coefficients. Due to low global regularity of the solution, it is difficult to achieve optimal order of convergence with classical finite element methods [ Numer. Math. 1998; 79:175–202]. In this paper, an isoparametric type of discretization is used to prove optimal order error estimates in L 2 and H 1 norms when the global regularity of the solution is low. The interface is assumed to be of arbitrary shape and is smooth for our purpose. Further, for the purpose of numerical computations, we discuss the effect of numerical quadrature on finite element solution, and the related optimal order estimates are also established. [ABSTRACT FROM AUTHOR]

This paper studies the behavior under iteration of the maps Tab(x, y) = (Fab(x) - y, x) of the plane R², in which Fab(x) = ax if x ≥ 0 and bx if x « 0. The orbits under iteration correspond to solutions of the nonlinear difference equation xn+2 = 1/2(a - b)[xn+1] + 1/2(a + b)xn+1 - xn. This family of piecewise-linear maps has the parameter space (a, b] ϵ R². These maps are area-preserving homeomorphisms of R² that map rays from the origin into rays from the origin. The action on rays gives an auxiliary map Sab: S¹ ↵ S¹ of the circle, which has a well-defined rotation number This paper characterizes the possible dynamics under iteration of Tab when the auxiliary map Sab has rational rotation number, It characterizes cases where the map Tab is a periodic map. [ABSTRACT FROM AUTHOR]

This paper describes students' solutions to a commonly taught and not commonly taught inequality. The findings showed students' difficulties. Participants implicitly and explicitly exhibited two intuitive beliefs: inequalities must result in inequalities and solving inequalities and equations are the same process . Following the analysis of students' written solutions, individual interviews were conducted that gave a better insight into their reasoning and provided some ideas for teaching. The concluding section of the paper offers relevant educational implications. [ABSTRACT FROM AUTHOR]

This paper deals with a fully implicit time discretization scheme with variable time-step for a nonlinear system modelling phase transition and mechanical deformations in shape memory alloys. The model is studied in the non-stationary case and accounts for local microscopic interactions between the phases introducing the gradients of the phase parameters. The resulting initial-boundary value problem has already been studied by the author who proved existence, uniqueness and continuous dependence on data for a suitable weak solution along some regularity results. A careful and detailed investigation of the variable time-step discretization is the goal of this paper. Thus, we deduce some estimates for the discretization error. These estimates depend only on data, impose no constraints between consecutive time-steps and show an optimal order of convergence. Finally, we prove another regularity result for the solution under stronger regularity assumptions on data. [ABSTRACT FROM AUTHOR]

Let D be a smooth bounded domain in . Let f be a positive monotone increasing function on which satisfies the Keller-Osserman condition. It is well-known that the solutions of Δ u = f ( u ), which blow up at the boundary behave, to a first order approximation, like a function of dist( x ,∂ D ). In this paper we show that the second order approximation depends on the mean curvature of ∂ D . This paper is an extension of results in [4] which dealt with radially symmetric solutions. It extends also the results in [5] for f = t p . [ABSTRACT FROM AUTHOR]

In a recent paper [4], Li et al . gave a generalized successive overrelaxation (GSOR) method for the least squares problems. In this paper, the connection between the GSOR method and the preconditioned conjugate gradient (PCG) method for the normal equations is investigated. It is shown that the PCG method is at least as fast as the GSOR method. Numerical examples demonstrates that the PCG method is much faster than the GSOR method. [ABSTRACT FROM AUTHOR]

In this paper, we study the Gevrey regularity of weak solutions for a class of linear and semi-linear kinetic equations, which are the linear model of spatially inhomogeneous Boltzmann equations without an angular cutoff. [ABSTRACT FROM AUTHOR]

We consider a nonoscillatory second-order linear dynamic equation on a time scale together with a linear perturbation of this equation and improve recently given conditions on the perturbation that guarantee that the perturbed equation is also nonoscillatory and has solutions that behave asymptotically like a recessive and a dominant solution of the unperturbed equation. The presented results are time scales analogues of a 2002 paper on the differential equations case by Trench. The difference equations case has not been treated yet, but is contained in our study together with other cases of dynamic equations. [ABSTRACT FROM AUTHOR]

In this article we stochastically perturb the classical non-autonomous delay Lotka-Volterra model [image omitted] into the stochastic delay population system (SDPS) [image omitted] Different from most of the existing papers [A. Bahar and X. Mao, Stochastic delay Lotka-Volterra model, J. Math. Anal. Appl. 292 (2004), 364-380, A. Bahar and X. Mao, Stochastic delay population dynamics, J. Pure Appl. Math. 11 (2004), 377-400, X. Mao, Delay population dynamics and environmental noise, Stochastics Dyn. 5(2) (2005), pp. 149-162], the system parameters in this article are time-dependent. We will give a sufficient condition under which the SDPS will have a unique global positive solution. We will then establish some new asymptotic properties for the moments of the solution. In particular, we will discuss two fundamental problems in population systems, namely ultimate boundedness and extinction. [ABSTRACT FROM AUTHOR]

The basic rules of elementary algebra can often appear beyond the grasp of many students. Even though most subjects, including calculus, prove to be more difficult, it is the simple rules of algebra that continue to be the “thorn in the side” of many mathematics students. In this paper we present a result intended to help students achieve a greater understanding of a familiar algebraic error. [ABSTRACT FROM AUTHOR]

The article presents the first part of a paper about second-order rational difference equations. This study aims to demonstrate the results of the global character of solutions of a second-order rational difference equation. Moreover, a number of open problems and conjectures related to the topic will also be presented in the article.

In the original work by Burnett, the pressure tensor and the heat current contain two time derivates. Those are commonly replaced by spatial derivatives using the equations to zero order in the Knudsen number. The resulting conventional Burnett equations were shown by Bobylev to be linearly unstable. In this paper it is shown that the original equations of Burnett have a singularity. A hybrid of the original and conventional equations is constructed and shown to be linearly stable. It contains two parameters, which have to be larger than or equal to some limit values. For any choice of the parameters, the equations agree with each other and with the Burnett equations to second order in Kn, that is, to the accuracy of the Burnett equations. For the simplest choice of parameters the hybrid equations have no third derivative of the temperature, but the inertia term contains second spatial derivatives. For stationary flow, when the terms Kn2Ma2 can be neglected, the only difference from the conventional Burnett equations is the change of coefficients ϖ2→ϖ3, ϖ3→ϖ3. [ABSTRACT FROM AUTHOR]

This paper gives a quantitative control of the order of zero of a weak solution to perturbations of the Baouendi-Grushin operator, which generalizes the result due to Aronszaijn, Krzywicki, and Szarski valid for elliptic operators in divergence form with Lipschitz continuous coefficients. [ABSTRACT FROM AUTHOR]

In this paper, we present C∞ examples of degenerate hyperbolic and mixed type Monge-Ampère equations in the plane, which do not admit a local C3 solution. [ABSTRACT FROM AUTHOR]

This paper studies the boundedness character of the positive solutions of the difference equation.[image omitted] where [image omitted] with [image omitted] . We prove that if [image omitted] , then every solution of the equation is bounded, and if [image omitted] and k is even, then there exist positive unbounded solutions. For the case [image omitted] and k odd, we consider the related equation [image omitted] and show that every integer solution is eventually periodic. [ABSTRACT FROM AUTHOR]

In this paper an attempt has been made to analyze a multimachine system composed of a number of self-excited induction generators (SEIG). A simple model has been proposed to carry out the steady state analysis of the system. The model results in a single equation for terminal voltage in contrast to a number of equations as obtained by many other researchers. Computed results have been verified using experimental results on a system including two self-excited induction generators. [ABSTRACT FROM AUTHOR]

In this paper, we will study the max difference equation in the title when is a constant sequence or period-four sequence of real numbers greater than one. In the former case, we provide an alternative proof to that already given in Amleh, Hoag, and Ladas, 1998, A difference equation with eventually periodic solutions, Computers and Mathematics with Applications , 36, 401–404, and Grove and Ladas, 2005, Periodicities in Nonlinear Difference Equations (Boca Raton: Chapman & Hall/CRC), where we show that every solution is eventually periodic with period 4. We prove that every solution is eventually periodic with period 8 in the latter case. [ABSTRACT FROM AUTHOR]

In this paper a Petrov–Galerkin method is used to derive a numerical solution for the K (2, 2) equation, where we have chosen cubic B-splines as test functions and piecewise linear functions as trial functions. The product approximation technique is applied to the nonlinear terms. A Crank–Nicolson scheme is used to discertize in time. A nonlinear pentadiagonal system is obtained. We solve this system by Newton’s method and a linearization technique. The accuracy and stability of the scheme have been investigated. The single compacton solution and the conserved quantities are used to assess the accuracy of the scheme. The interaction of two compactons are displayed and the numerical results have shown that this compacton exhibits a soliton-like solution. [ABSTRACT FROM AUTHOR]

In this paper we combine the techniques of the Malliavin and the fractional calculus to establish a Clark-Ocone integral representation for fractional Brownian motion with Hurst parameter . The uniqueness of this adapted representation is proved. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the set of solutions of a linear difference equation of high-order. More precisely, we obtain a basis of such a linear subspace. We deduce integral representations for elements of this basis. [ABSTRACT FROM AUTHOR]

This paper studies the behavior of positive solutions of the recursive equationwith We prove that every positive solution { y i } converges to a period two solution or to the equilibrium . This result answers Open Problem 11.4.8 (a) in Kulenovic and Ladas, 2002 Dynamics of Second Order Rational Difference Equations. With Open Problems and Conjectures (Boca Raton:Chapman and Hall/CRC). [ABSTRACT FROM AUTHOR]

In this paper, we study the existence of multiple positive solutions of boundary value problems for second-order discrete equations ? 2 x ( n - 1) - p ? x ( n - 1) - qx ( n - 1)+ f ( n , x ( n )) = 0, n ? {1,2,...}, ax (0) - ß? x (0) = 0, x (8) = 0. The proofs are based on the fixed point theorem in Fréchet space (see Agarwal and O'Regan, 2001, Cone compression and expansion and fixed point theorems in Fréchet spaces with application, Journal of Differential Equations , 171, 412–42). [ABSTRACT FROM AUTHOR]

In this paper, by using a so-called fixed steplength strategy, we propose a BFGS method without use of line searches for unconstrained optimization. Under mild conditions, we show the global and superlinear convergence of the proposed method even when the objective function is nonconvex. [ABSTRACT FROM AUTHOR]

In section 1, we correct an error in the proof of Lemma 3.1 in L. Alsedà, M.A. del Río, and J.A. Rodríguez. Transitivity and dense periodicity for graph maps. J. Difference Equ. Appl. 9, 577–598, 2003. In section 2 we give a simple proof that weak mixing implies mixing for maps on topological graphs. The proofs can also be extended to (nut necessarily compact) intervals, so in particular, this paper shows that for one-dimensional manifolds, weak mixing implies mixing. [ABSTRACT FROM AUTHOR]

In this paper we develop some techniques to obtain global hyperbolicity for a certain class of endomorphisms of with This kind of endomorphisms are obtained from vectorial difference equations where the mapping defining these equations satisfy a circulant condition. In particular, we show that one-parameter families of these quadratic endomorphisms are hyperbolic for large values of the parameter. [ABSTRACT FROM AUTHOR]

In this paper we study regularity properties of the free boundary problem where B + 1 = {| x | 0} and B 1 = {| x | [ABSTRACT FROM AUTHOR]

This paper is concerned with the analysis of the discontinuous Galerkin finite element method applied to the space semidiscretization of nonlinear nonstationary convection-diffusion problems. The attention is paid to the derivation of the method and the investigation of error estimates for schemes with a symmetric as well as nonsymmetric discretization of diffusion terms and with the interior and boundary penalty. The theoretical results are illustrated by numerical experiments. [ABSTRACT FROM AUTHOR]

In this paper, we consider an obstacle control problem where the state satisfies a quasilinear elliptic bilateral variational inequality and the control functions are the upper and the lower obstacles. Existence and necessary conditions for the optimal control are established. [ABSTRACT FROM AUTHOR]

In this paper, we study the asymptotic behavior of positive solutions of nonautonomous Beverton-Holt equationwhere { K n} is a positive persistent and bounded sequence. In our main result, we proved that all positive solutions { x n} satisfy the inequalityThe obtained result represents the extension of the Cushing-Hensons's conjecture. Applications to the case when { K n} is a positive periodic sequence are given and the alternative proof of the Cushing-Henson's conjecture is also presented. [ABSTRACT FROM AUTHOR]

In this paper we consider the 3D Navier–Stokes equations in O ? R 3 , not necessarily bounded. We prove the asymptotic stability for weak solutions in the class ? u ? L a (0, 8; L ? (O)) for with arbitrary initial and external perturbations. [ABSTRACT FROM AUTHOR]

The paper is concerned with strong solutions of bilinear stochastic wave equations in [Rscr]d, of which the coefficients contain semimartingale white noises with spatial parameters. For the Cauchy problems, the existence and spatial regularity of solutions in Sobolev spaces are proved under appropriate conditions. The dependence of solution regularity on the smoothness of the random coefficients is ascertained. The proofs are based on stochastic energy inequalities, the semigroup method and certain submartingale inequalities. Regularity results are also obtained for the special case of Wiener semimartingales. [ABSTRACT FROM AUTHOR]

The noncharacteristic Cauchy problem of heat equations is not well-posed. But the estimation on the continuous dependence of solutions holds under their prescribed bound and the bound of their Cauchy data. In this paper we show that a similar estimation holds also for some degenerate quasilinear parabolic equation. [ABSTRACT FROM AUTHOR]

In this note, we study positive solutions of the difference equation [This symbol cannot be presented in ASCII format] where p ∈ [1.∞) and s, l ∈ N. We prove that if p > 1, then every positive solution converges to the positive equilibrium x* = p + 1 and if p = 1, then every positive solution converges to a 2s-periodic solution. The second result generalizes the main result in the paper: W.T. Patula and H.D. Voulov. On the oscillation and periodic character of a third order rational difference equation. [ABSTRACT FROM AUTHOR]

In this paper, we attempt to investigate a class of constrained nonsmooth convex optimization problems, that is, piecewise C² convex objectives with smooth convex inequality constraints. By using the Moreau-Yosida regularization, we convert these problems into unconstrained smooth convex programs. Then, we investigate the second-order properties of the Moreau-Yosida regularization n. By introducing the (GAIPCQ) qualification, we show that the gradient of the regularized function n is piecewise smooth, thereby, semismooth. [ABSTRACT FROM AUTHOR]

In this paper we lay the ground work for the study of wave propagation through some helical slow wave structures in which the helices are wound on elliptical cylinders of very small eccentricity. The eccentricity is so small that it is assumed that the circular cylindrical coordinate system may be used. Some interesting results showing the effect of anisotropy on the characteristic dispersion equation are obtained. The standard characteristic equation for the modal index n = 0 for the circular helix as given in text books is retrieved showing that the analysis presented here is reliable. Fast wave helical structures of elliptical shape have been studied earlier by the authors. [ABSTRACT FROM AUTHOR]

The notion of equivalence relation is a fundamental concept in mathematics and yet mathematics students often are not given formal exposure to it until midway through their college careers. Not only do they need to become adept at working with equivalence relations but they should also understand the wide applicability of this notion. In this paper collaborative exercises are provided for students to gain facility with equivalence relations and their classes, as well as to see their usefulness in various areas of mathematics and computer science. [ABSTRACT FROM AUTHOR]

We consider a positive C²-function u in Rn which is equal to two different spherical solutions respectively in two disjoint domains, u satisfies the equation Δu + n(n - 2)Kun+2/n-2 = 0 in Rn. By a result of Gidas, Ni and Nirenberg, K ... 1 in Rn. In this paper we discuss lower bounds on supRn K -1. The estimates are applied to study blow-up solutions and interaction of bubbles. [ABSTRACT FROM AUTHOR]