Qualitative Analysis of Differential Equations

It is our pleasure to provide this special issue on qualitative analysis of differential equations in International Journal of Differential Equations. Qualitative analysis has proved to be an important and useful tool to investigate the properties of solutions of differential equations, because it enables to analyze differential equations without solving analytically and numerically. The study of qualitative properties of differential equations has a long history, and qualitative theories have been developed for various equations such as ordinary differential equations, functional differential equations, abstract differential equations, dynamical systems, integral equations, difference equations, partial differential equations, functional partial differential equations and so forth. Since the qualitative analysis of differential equations is related to both pure and applied mathematics, its applications to various fields such as science, engineering, and ecology have been extensively developed. This special issue contains papers which treat a number of important and attractive problems related to existence of positive periodic solutions for periodic neutral Lotka-Volterra system with distributed delays and impulses, dynamics of a Gross-Pitaevskii equation with phenomenological damping, characterization for rectifiable and nonrectifiable attractivity of nonautonomous systems of linear differential equations, positive periodic solutions of cooperative systems with delays and feedback controls, oscillations of a class of forced second-order differential equations with possible discontinuous coefficients, analysis of mixed elliptic and parabolic boundary layers with corners, unboundedness of solutions of Timoshenko beam equations with damping and forcing terms, and fractal oscillations of chirp functions and applications to second-order linear differential equations. The paper by Z. Luo and L. Luo discusses the existence of positive periodic solutions for a class of impulsive neutral Lotka-Volterra system with distributed delays by using a fixed point theorem of strict-set contraction. Some criteria that guarantee the existence of at least one positive periodic solution of the system are established. The research article of R. Colucci et al. deals with the dynamical behavior of solutions of an -dimensional nonlinear Schr？dinger equation with potential and linear derivative terms under the presence of phenomenological damping. The authors of that paper obtain conditions for the existence of a compact global attractor and find bounds for its Hausdorff and