1,721,007 research outputs found
Global nonlinear stability and "cold convection instability" of non-constant porous throughflows, 2D in vertical planes
No full textPorous horizontal layers are considered. A class of non-constant porous throughflows, 2D in vertical planes, is obtained. The global stability conditions
and the "cold convection instability'' conditions are investigated
On the long-time dynamics of nonautonomous predator-prey models with mutual interference
No full textThe longtime behaviour of a nonautonomous bidimensional Hassell predator-prey model with mutual interference is investigated. The existence of an absorbing set in the phase space is shown, and necessary and sufficient conditions guaranteeing the nonlinear, global, asymptotic stability of the positive solutions have been found by using the Liapunov direct method
Global Stability for a binary reaction-diffusion Lotka-Volterra model with ratio-dependent functional response
No full textA reaction-diffusion system modeling the predation between two species is analyzed in the case in which the predators have to search, share and compete for food. The boundedness and uniqueness of the solutions is proved and conditions guaranteeing the global nonlinear asymptotic stability of the positive equilibrium point have been found. These conditions improve those ones present in the existing literature
Convection in multi-component rotating fluid layers via the auxiliary system method
No full textThe onset of thermal convection in a uniformly rotating horizontal layer filled by a Navier-Stokes multi-component fluid mixture, heated from below and salted partly from above and partly from below, is investigated via the new approach named auxiliary system method Rionero (Rend Lincei Mat Appl 25:1-44, 2014). In the free-free case, via the generalization of the Rionero Linearization Principle: "Decay of linear energy for any initial data implies decay of nonlinear energy at any instant" [given in Rionero (Rend Lincei Mat Appl 25:1-44, 2014) in the absence of rotation], it is shown that conditions guaranteeing linear stability of thermal conduction solution guarantee also absence of subcritical instabilities and global exponential asymptotic nonlinear stability. The classical Benard problem is investigated via a procedure different from the celebrated one given in Chandrasekhar (Hydrodynamic and hydromagnetic stability, 1981)
Double diffusive convection in porous media under the action of a magnetic field
No full textThe onset of thermal convection in an electrically conducting fluid saturating a porous medium, uniformly heated from below, salted by one chemical and embedded in an external transverse magnetic field is analyzed. The critical Rayleigh thermal numbers at which steady and Hopf convection can occur, are determined. Sufficient conditions guaranteeing the effective onset of convection via steady or oscillatory state are provided
Onset of convection for ternary fluid mixtures saturating horizontal porous layers with large pores
No full textTernary fluid mixtures saturating horizontal porous layers with large pores, uniformly rotating around the vertical axis, are investigated. The layers are heated from below, salted from above and from below by two salts. The stabilizing effects of both the rotation and Brinkman terms on the conduction solution are analyzed
Coincidence between linear and global nonlinear stability of non-constant throughflows via the Rionero "Auxiliary System Method"
No full textA system modeling fluid motions in horizontal
porous layers, uniformly heated and salted from below, is
analyzed in the case of variable thermal and solutal diffusivities.
The boundedness and uniqueness of solutions are
shown. A class of non-constant throughflows is found and
their stability is analyzed via a new approach. Conditions of
global nonlinear stability, in closed form, are obtained
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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