Results 11 to 20 of about 8,669,989 (253)
On the Number of Nonnegative Solutions to the Inequality a1 +....ar < n [PDF]
, 2010 In this paper, we present a simple and fast method for counting the number of nonnegative integer solutions to the equality a1x1+a2x2+: : :+arxr = n where a1; a2; :::; ar and n are positive integers.
Farzaneh , A. +3 more
core +9 more sources
Existence of solutions for Kirchhoff-type problems via the method of lower and upper solutions [PDF]
Electronic Journal of Differential Equations, 2019 This article considers elliptic problems of Kirchhoff-type. We give some new definitions of lower and upper solutions for the problem and establish the method of lower and upper solutions when the upper and lower solutions are well ordered, i.e., the ...
Baoqiang Yan +2 more
doaj +3 more sources
3D ultimate limit state analysis using discontinuity layout optimization [PDF]
, 2012 The recently developed discontinuity layout optimization (DLO) procedure uses limit analysis theory to directly obtain upper bounds on plane strain collapse loads of bodies and has successfully been applied to geotechnical problems.
Hawksbee, Samuel John
core +6 more sources
The method of upper, lower solutions and hyperbolic partial differential equations
Journal of Mathematical Analysis and Applications, 1985 The authors extend the method of sub- and super-solutions to some initial value problems for certain nonlinear hyperbolic equations. They prove existence theorems and obtain minimal solutions. \{Reviewer's remark: It seems to the reviewer that their requirements on sub- and supersolutions are very restrictive.\}
Lakshmikantham, V, Pandit, S.G
openaire +2 more sources
Almost Periodic Solutions of First-Order Ordinary Differential Equations
Mathematics, 2018 Approaches to estimate the number of almost periodic solutions of ordinary differential equations are considered. Conditions that allow determination for both upper and lower bounds for these solutions are found.
Seifedine Kadry +3 more
doaj +1 more source
Discrete and Continuous Dynamical Systems - B, 2019 We prove existence and uniqueness of weak and classical solutions to certain semi-linear parabolic systems with Robin boundary conditions using the coupled upper-lower solution approach. Our interest lies in cross-dependencies on the gradient parts of the reaction term, which prevents the straight-forward application of standard theorems.
Anne Mund +2 more
openaire +1 more source
The upper–lower solution method for the coupled system of first order nonlinear PDEs
Journal of Mathematical Analysis and Applications, 2013 Abstract This paper is concerned with a coupled system of first order nonlinear partial differential equations. This system is, but not limited in, the extended case of the general blood–tissue exchange model (BTEX). We use the solutions of a coupled system of first order ordinary differential equations to construct a pair of ordered lower and upper ...
Guo-Chin Jau, Yu-Hsien Chang
openaire +1 more source
Causal difference equations with upper and lower solutions in the reverse order
Advances in Difference Equations, 2019 This paper is devoted to studying the existence conditions for difference equations involving causal operators in the presence of upper and lower solutions in the reverse order. To this end, we prove some new comparison theorems and develop the upper and
Wen-Li Wang, Jing-Feng Tian
doaj +1 more source
Lower semicontinuity of attractors for non-autonomous dynamical systems [PDF]
, 2009 This paper is concerned with the lower semicontinuity of attractors for semilinear non-autonomous differential equations in Banach spaces. We require the unperturbed attractor to be given as the union of unstable manifolds of time-dependent hyperbolic
Langa, José A. +3 more
core +1 more source
On positive solutions of the Dirichlet problem involving the extrinsic mean curvature operator
Electronic Journal of Qualitative Theory of Differential Equations, 2016 In this paper, we are concerned with necessary conditions for the existence of positive solutions of the Dirichlet problem for the prescribed mean curvature equation in Minkowski space \begin{equation*} \begin{aligned} -\text{div}\left(\frac {\nabla u}{\
Ruyun Ma, Tianlan Chen, Hongliang Gao
doaj +1 more source