<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>1405-5546</journal-id>
<journal-title><![CDATA[Computación y Sistemas]]></journal-title>
<abbrev-journal-title><![CDATA[Comp. y Sist.]]></abbrev-journal-title>
<issn>1405-5546</issn>
<publisher>
<publisher-name><![CDATA[Instituto Politécnico Nacional, Centro de Investigación en Computación]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1405-55462003000200004</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Bifurcaciones de Hopf: Análisis Cualitativo y Aplicación a un Modelo Bioeconómico de Pesquerías]]></article-title>
<article-title xml:lang="en"><![CDATA[Hopf Bifurcations: Qualitative Analysis and Application to a Bioeconomic Model of Fisheries]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Vílchez Lobato]]></surname>
<given-names><![CDATA[Ma. Luisa]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Velasco Morente]]></surname>
<given-names><![CDATA[Francisco]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[González Abril]]></surname>
<given-names><![CDATA[Luis]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ortega]]></surname>
<given-names><![CDATA[Juan Antonio]]></given-names>
</name>
<xref ref-type="aff" rid="A03"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad de Huelva 1Departamento de Economía General y Estadística ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>España</country>
</aff>
<aff id="A02">
<institution><![CDATA[,Universidad de Sevilla Departamento de Economía Aplicada I ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>España</country>
</aff>
<aff id="A03">
<institution><![CDATA[,Universidad de Sevilla Departamento de Lenguajes y Sistemas Informáticos ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2003</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2003</year>
</pub-date>
<volume>6</volume>
<numero>4</numero>
<fpage>273</fpage>
<lpage>283</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S1405-55462003000200004&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S1405-55462003000200004&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S1405-55462003000200004&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Realizamos en este trabajo un estudio cualitativo de las trayectorias del sistema dinámico resultante de aplicar el Principio del Máximo de Pontryagin a un problema de control óptimo para la gestión económica de una pesquería. Analizamos la estabilidad de las soluciones de equilibrio estacionario en función de los parámetros del sistema, para posteriormente investigar sobre la existencia de bifurcaciones de codimensión uno. En este sentido, centramos particularmente nuestra atención en la bifurcación de Hopf y en la consiguiente aparición de trayectorias cerradas de tipo ciclo límite. Los resultados obtenidos a nivel teórico son ilustrados empíricamente asignando a los parámetros del sistema las estimaciones realizadas para el caso de la pesquería de "chamelea gallina" del litoral suratlántico español. Los valores de bifurcación se obtienen mediante el uso de los softwares Content y Vensim y se da una descripción del comportamiento cualitativo de las órbitas del sistema en los entornos de los valores de bifurcación.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[This paper deals with the theory of codimension one bifurcations applied to a dynamical system derived from applying Pontryagin's maximum principle to an optimal control problem for economic fisheries management Changes in the number and/or the stability of stationary states as well as the appearance of closed orbits, are analyzed. Some necessajy and/or sufficient conditions are established for the existence of Hopf bifurcations, according to the biological and economic parameters of the model. We focus our attention on the resulting limit cycles which can be candidates for solutions of the optimal control problem. The method is applied to the South Atlantic "chamelea gallina" fishery. To obtain the bifurcation values, we have made numerical computations by the use of Content and Vensim software. So, we make a qualitative description of the trajectories behaviour around the stationary states.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Estabilidad]]></kwd>
<kwd lng="es"><![CDATA[Bifurcaciones]]></kwd>
<kwd lng="es"><![CDATA[Teorema de Hopf]]></kwd>
<kwd lng="es"><![CDATA[Ciclo Límite]]></kwd>
<kwd lng="es"><![CDATA[Control Óptimo]]></kwd>
<kwd lng="en"><![CDATA[Stability]]></kwd>
<kwd lng="en"><![CDATA[Bifurcations]]></kwd>
<kwd lng="en"><![CDATA[Hopf Theorem]]></kwd>
<kwd lng="en"><![CDATA[Limit Cycle]]></kwd>
<kwd lng="en"><![CDATA[Optimal Control]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">Art&iacute;culos</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><b>Bifurcaciones de Hopf: An&aacute;lisis Cualitativo y Aplicaci&oacute;n a un Modelo Bioecon&oacute;mico de Pesquer&iacute;as</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><i>Hopf Bifurcations: Qualitative Analysis and Application to a Bioeconomic Model of Fisheries</i></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>Ma. Luisa V&iacute;lchez Lobato<sup>1</sup>, Francisco Velasco Morente<sup>2</sup>, Luis Gonz&aacute;lez Abril<sup>2</sup> y Juan Antonio Ortega<sup>3</sup></b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><i>1Departamento de Econom&iacute;a General y Estad&iacute;stica, Universidad de Huelva, Espa&ntilde;a, Plaza de la Merced s/n    <br>   2 Departamento de Econom&iacute;a Aplicada I, Universidad de Sevilla, Espa&ntilde;a, Avda, Ram&oacute;n y Cajal no. 1     ]]></body>
<body><![CDATA[<br>   3 Departamento de Lenguajes y Sistemas Inform&aacute;ticos, Universidad de Sevilla, Espa&ntilde;a, Avda. Reina Mercedes</i></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>E&#150;mail:</b> <a href="mailto:lobato@uhu.es">lobato@uhu.es</a>, <a href="mailto:velasco@us.es">velasco@us.es</a>, <a href="mailto:velasco@us.es">luisgon@us.es</a>, <a href="mailto:ortega@lsi.us.es">ortega@lsi.us.es</a></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><u>Art&iacute;culo recibido en Mayo 05, 2002; aceptado en Abril 18, 2003</u></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     <p align="justify"><font face="verdana" size="2"><i>Realizamos en este trabajo un estudio cualitativo de las trayectorias del sistema din&aacute;mico resultante de aplicar el Principio del M&aacute;ximo de Pontryagin a un problema de control &oacute;ptimo para la gesti&oacute;n econ&oacute;mica de una pesquer&iacute;a. Analizamos la estabilidad de las soluciones de equilibrio estacionario en funci&oacute;n de los par&aacute;metros del sistema, para posteriormente investigar sobre la existencia de bifurcaciones de codimensi&oacute;n uno. En este sentido, centramos particularmente nuestra atenci&oacute;n en la bifurcaci&oacute;n de Hopf y en la consiguiente aparici&oacute;n de trayectorias cerradas de tipo ciclo l&iacute;mite. Los resultados obtenidos a nivel te&oacute;rico son ilustrados emp&iacute;ricamente asignando a los par&aacute;metros del sistema las estimaciones realizadas para el caso de la pesquer&iacute;a de "chamelea gallina" del litoral suratl&aacute;ntico espa&ntilde;ol. Los valores de bifurcaci&oacute;n se obtienen mediante el uso de los softwares Content y Vensim y se da una descripci&oacute;n del comportamiento cualitativo de las &oacute;rbitas del sistema en los entornos de los valores de bifurcaci&oacute;n.</i></font></p>     <p align="justify"><font face="verdana" size="2"><b>Palabras clave:</b> Estabilidad, Bifurcaciones, Teorema de Hopf, Ciclo L&iacute;mite, Control &Oacute;ptimo.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2"><i>This paper deals with the theory of codimension one bifurcations applied to a dynamical system derived from applying Pontryagin's maximum principle to an optimal control problem for economic fisheries management Changes in the number and/or the stability of stationary states as well as the appearance of closed orbits, are analyzed. Some necessajy and/or sufficient conditions are established for the existence of Hopf bifurcations, according to the biological and economic parameters of the model. We focus our attention on the resulting limit cycles which can be candidates for solutions of the optimal control problem. The method is applied to the South Atlantic "chamelea gallina" fishery. To obtain the bifurcation values, we have made numerical computations by the use of Content and Vensim software. So, we make a qualitative description of the trajectories behaviour around the stationary states.</i></font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords:</b> Stability, Bifurcations, Hopf Theorem, Limit Cycle, Optimal Control.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><font face="verdana" size="2"><font size="2" face="verdana"><a href="/pdf/cys/v6n4/v6n4a4.pdf" target="_blank">DESCARGAR ARTICULO EN FORMATO PDF</a></font></font></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Agradecimientos</b></font></p>     <p align="justify"><font face="verdana" size="2">Este trabajo ha sido soportado parcialmente por la ayuda de la Junta de Andaluc&iacute;a (ACC&#150;354&#150;SEJ&#150;2001) (ACC&#150;944&#150;SEJ&#150;2002).</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Bibliograf&iacute;a</b></font></p>     ]]></body>
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