accedaCRIShttps://accedacris.ulpgc.es/jspuiThe accedaCRIS digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 02 Dec 2023 18:19:54 GMT2023-12-02T18:19:54Z50111Application of a nonlinear evolution model to fire propagationhttp://hdl.handle.net/10553/45257Title: Application of a nonlinear evolution model to fire propagation
Authors: Montenegro, R.; Plaza, A.; Ferragut, L.; Asensio, M. I.
Abstract: The numerical simulation of fire in forest has been an important objective in recent researches, The rate of spread and shape of a forest fire front is af8ecte.d by many factors. The most important of these are as follows: fuel type and moisture content, wind velocity and variability, forest topography, fire spread mechanism, fuel continuity and the amount of spotting (cf.[ l-21). The development of Geographic Information Systems allows the incorporation of these data to the developed models, The first models took into account constant factors, continuous uniform fuel type, constant wind velocity, moisture and slope. Under these conditions, a fire ignited at a single point reaches a quasi-steady state and progresses toward the down wind direction and expands at a constant rate. These data cannot give precise predictions under variable conditions but are very useful in order to the intuition of the fire controller. Models capable of being incorporated into the computer simulations of fires under variable conditions have been developed, based on cellular automata (cf. [3-7]), and stochastic process [8]. These models can give useful indicators as to fire behavior under such conditions. Combustion phenomena has been extensively studied [9], unsteady flame propagation has been analyzed [lo]. Models based on combustion theories are very difficult to develop because of the diversity of the fuel type and varied chemical composition within a given fuel type. Because of the complexity of the problem, models based rigorously on combustion theory have not been completely developed. In this preliminary work, a first attempt is done to design a computer code for numerical simulation of forest fire spread in landscapes. Basically a convection-diffusion model for temperature and a mass-consistent model for wind field simulation will be assumed. A two-steps chemical mechanism is simplified in order to obtain the heat source. This proposed 2-D model take into account the convection phenomena due to temperature gradients in vertical direction. A numerical solution of the former model is presented using a finite difference method together with the study of stability. This numerical method is contrasted with an adaptive finite element method using reflnementiderefinement techniques (cf. [ 1 1 - 143}).
Wed, 01 Jan 1997 00:00:00 GMThttp://hdl.handle.net/10553/452571997-01-01T00:00:00ZOn some measures of noncompactness in the space of continuous functionshttp://hdl.handle.net/10553/46756Title: On some measures of noncompactness in the space of continuous functions
Authors: Banaś, Józef; Sadarangani, Kishin
Abstract: We consider some quantities in the space of functions continuous on a bounded interval, which are related to monotonicity of functions. Based on those quantities we construct a few measures of noncompactness in the mentioned function space. Several properties of those measures are established; among others it is shown that they are regular or “partly” regular measures and equivalent to the Hausdorff measure of noncompactness.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10553/467562008-01-01T00:00:00ZOn existence and asymptotic behaviour of solutions of a functional integral equationhttp://hdl.handle.net/10553/42755Title: On existence and asymptotic behaviour of solutions of a functional integral equation
Authors: Banaś, Józef; Cabrera, Ignacio J.
Abstract: The paper contains a result on the existence and asymptotic behaviour of solutions of a functional integral equation. That result is proved under rather general hypotheses. The main tools used in our considerations are the concept of a measure of noncompactness and the classical Schauder fixed point principle. The investigations of the paper are placed in the space of continuous and tempered functions on the real half-line. We prove an existence result which generalizes several ones concerning functional integral equations and obtained earlier by other authors. The applicability of our result is illustrated by some examples.
Mon, 01 Jan 2007 00:00:00 GMThttp://hdl.handle.net/10553/427552007-01-01T00:00:00ZA Cauchy-Schwarz type inequality for fuzzy integralshttp://hdl.handle.net/10553/46749Title: A Cauchy-Schwarz type inequality for fuzzy integrals
Authors: Caballero, J.; Sadarangani, K.
Abstract: In this paper we prove a Cauchy-Schwarz type inequality for fuzzy integrals.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10553/467492010-01-01T00:00:00ZCompactness conditions and strong subdifferentiability of a norm in geometry of Banach spaceshttp://hdl.handle.net/10553/46764Title: Compactness conditions and strong subdifferentiability of a norm in geometry of Banach spaces
Authors: Banaś, Józef; Sadarangani, Kishin
Abstract: Connections between concepts of geometric theory of Banach spaces and concept of Asplund space were established. Characterization of separable Asplund spaces was performed with the help of compactness conditions of the geometry of Banach spaces. Relationships among the conditions and subdifferentiability of the norm of Banach spaces were also indicated.
Tue, 01 Jan 2002 00:00:00 GMThttp://hdl.handle.net/10553/467642002-01-01T00:00:00ZOn a nonlinear quadratic integral equation of Urysohn-Stieltjes type and its applicationshttp://hdl.handle.net/10553/46765Title: On a nonlinear quadratic integral equation of Urysohn-Stieltjes type and its applications
Authors: Bana, Józef; Rodriquez, Juan Ramon; Sadarangani, Kishin
Abstract: In this paper we study the solvability of the quadratic integral equation of Urysohn-Stieltjes type. Equation of such a type generalizes numerous functional and integral equations considered in nonlinear analysis. The main tool used in the investigation is the technique of measures of noncompactness. We will discuss some connections of the integral equation considered here with the traffic, biology and probability theory.
Mon, 01 Jan 2001 00:00:00 GMThttp://hdl.handle.net/10553/467652001-01-01T00:00:00ZSolving optimal control problems by GAshttp://hdl.handle.net/10553/47210Title: Solving optimal control problems by GAs
Authors: Montero, G.
Wed, 01 Jan 1997 00:00:00 GMThttp://hdl.handle.net/10553/472101997-01-01T00:00:00ZGeneralized contractions in partially ordered metric spaces and applications to ordinary differential equationshttp://hdl.handle.net/10553/44263Title: Generalized contractions in partially ordered metric spaces and applications to ordinary differential equations
Authors: Harjani, J.; Sadarangani, K.
Abstract: The purpose of this paper is to present some fixed point theorems in a complete metric space endowed with a partial order by using altering distance functions. We also present some applications to first and second order ordinary differential equations.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10553/442632010-01-01T00:00:00ZFixed point theorems for mixed monotone operators and applications to integral equationshttp://hdl.handle.net/10553/44257Title: Fixed point theorems for mixed monotone operators and applications to integral equations
Authors: Harjani, J.; López Brito, María Belén; Sadarangani, K.
Abstract: The purpose of this paper is to present some coupled fixed point theorems for a mixed monotone operator in a complete metric space endowed with a partial order by using altering distance functions. We also present an application to integral equations.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10553/442572011-01-01T00:00:00ZSome qualitative properties for geometric flows and its Euler implicit discretizationhttp://hdl.handle.net/10553/52596Title: Some qualitative properties for geometric flows and its Euler implicit discretization
Authors: Alvarez, Luis; Díaz, Gregorio; Díaz, Jesús Ildefonso
Abstract: We study the geometric flow parabolic equation and its implicit discretization which yield a family of nonlinear elliptic problems. We show that there are important differences in the study of those equations which concerns the propagation of level sets of data. Our study is based on the previous study of radially symmetric solutions of the corresponding equation. Curiously, in radial coordinates both equations reduce to suitable singular Hamilton-Jacobi first order equations. After considering the case of monotone data we point out a new peculiar behavior for non-monotone data with a profile of Batman type (g=min{g1,g2},g1(r) increasing, g2(r) decreasing and g1(rd)=g2(rd) for some rd>0). In the parabolic regime, and when the velocity of the convexity part of the level sets is greater than the velocity of the concavity part, we show that the level set {u=g(rd)} develops a non-empty interior set for any t>0. Nothing similar occurs in the stationary regime. We also present some numerical experiences.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10553/525962016-01-01T00:00:00ZFixed point theorems for weakly contractive mappings in partially ordered setshttp://hdl.handle.net/10553/44264Title: Fixed point theorems for weakly contractive mappings in partially ordered sets
Authors: Harjani, J.; Sadarangani, K.
Abstract: The purpose of this paper is to present some fixed point theorems for weakly contractive maps in a complete metric space endowed with a partial order.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10553/442642009-01-01T00:00:00Z