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Kaiyin Huang

Publications and source records attributed to Kaiyin Huang.

5 recordsLinked to original sources

Necessary conditions for existence of tensor invariants for general nonlinear dynamical systems

The integrability has been playing an essential role in the field of differential equations. This property may better help us obtain the topological structure and even the global dynamics for the considered system. A system is called integrable if it has a number of tensor invariants, which can comprehensively define the integrability problem. In this paper, we give necessary conditions for existence of tensor invariants for general nonlinear systems, especially semi-quasihomogeneous systems. Our results may be viewed as a generalization of Poincaré and Kozlov's work.

math.DS↗

"Hidden" mechanisms for Gouy-Chapman layer and other critical features via Poisson-Boltzmann equations

In this work a dynamical system approach is taken to systematically investigate the one-dimensional classical Poisson-Boltzmann (PB) equation with various boundary conditions. This framework, particularly, the phase space portrait, has a unique advantage of a geometric view of the dynamical systems, which allows one to reveal and examine critical features of the PB models. More specifically, we are able to reveal the mechanism of Gouy-Chapman layer: the presence of an {\em equilibrium} for the PB equation, including equilibrium-at-infinity for Gouy-Chapman's original setup as the limiting case. Several other critical, somehow counterintuitive, features revealed in this work are the saturation phenomenon of surface charge density, the uniform boundedness of electric pressure (given length) and of length (given electric pressure) in surface charge, and the critical length for a reversal of electric force direction. All have a common mechanism: the presence of an equilibrium for the PB equation. We believe that the critical features presented from the classical PB models persist for modified PB systems up to a certain degree. On the other hand, any qualitative change in these features as the sophistication of the model is increasing is an indication of new phenomena with new mechanisms.

math.CA↗

Local first integrals for stochastic differential equations

Poincaré's classical results [H. Poincaré, Sur l'intégration des équations différentielles du premier order et du premier degré I and II, Rend. Circ. Mat. Palermo 5 (1891) 161-191; 11 (1897) 193-239] first provide a link between the existence of analytic first integrals and the resonant relations for analytic dynamical systems. In this paper, we show that by appropriately selecting the definition of the stochastic local first integrals, we are able to obtain the stochastic version of Poincaré non-integrability theorem. More specifically, we introduce two definitions of local first integrals for stochastic differential equations (SDEs) in the sense of probability one and expectation, respectively. We present the necessary conditions for the existence of functionally independent analytic or rational first integrals of SDEs via the resonances. We also show that for given integrable ordinary differential equations with some nondegeneracy conditions, there exists a linear stochastic perturbation such that the corresponding disturbed SDEs have no any analytic first integrals. Some examples are given to illustrate our results.

math.DG↗

On a simple model for describing convection of the rotating fluid: integrability, bifurcations and global dynamics

The Glukhovsky-Dolzhansky (GD) model arises naturally from geophysical science, which describes rotating fluid convection inside the ellipsoid. This work aims to provide some new insights into the GD model. (\emph{i}) We first show that, under some conditions there are homothetic transformations which covert the GD model into other similar quadric physical models, therefore, our results on the GD model can be naturally applied to the investigation of these models. (\emph{ii}) We propose a complete classification of Darboux polynomials and exponent factors for the GD model, which implies that the GD model has no polynomial, rational, or Darboux first integrals. In addition, some integrable cases of the GD model are also given when the physical parameters are allowed to be non-positive. (\emph{iii}) The existence of global attractor is proved. The stability and local bifurcations of all co-dimension one and two are investigated. Particularly, we show that the GD model undergoes two dynamical transitions as the Rayleigh number increases. (\emph{iv}) To understand the asymptotic behavior of the orbits for the GD model, we use the Poincaré compactification method to study its dynamical behavior at infinity. More precisely, we prove that the phase portraits of the GD model at infinity consist of an infinite sequence of periodic solutions and two heteroclinic loops. Our results may help us better understand the complex and rich dynamics of rotating fluid convection.

math.DS↗

Differential Galoisian approach to Jacobi integrability of general analytic dynamical systems and its application

The Morales-Ramis theory provides an effective and powerful non-integrability criterion for complex analytical Hamiltonian systems via the differential Galoisian obstruction. In this paper we give a new Morales-Ramis type theorem on the meromorphic Jacobi non-integrability of general analytic dynamical systems. The key point is to show the existence of Jacobian multiplier of a nonlinear system implies the existence of common Jacobian multiplier of Lie algebra associated with the identity component. In addition, we apply our results to the polynomial integrability of Karabut systems for stationary gravity waves in finite depth.

math.CA↗