Revista de Matemáticas 5(1)

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  • Ítem
    Generalización a Rn de algunos métodos de interpolación conocidos en ecuaciones diferenciales
    (2009-02-18 00:00:00) Arguedas Troyo, Vernor; Mata Montero, Roberto
    We present the Runge-Kutta methods of several one-step levels in Rn , as well as algorithms in pseudo-code for the implicit and explicit methods. We study the problem of error control in Rn and we give numerical examples in tables or parameter schemata.Keywords: n-dimensional runge-Katta methods, explicit and implicit methods, interpolation, pseudo-algorithms, parametric schema.
  • Ítem
    Métodos no estándar en el problema de la parada óptima
    (2009-02-18 00:00:00) Lobo Segura, Jaime
    We analize the optimal-stopping ploblem by the use of non standard analysis techniques. Using the non standard concept of quasi-optimal time, we prove the existence of optimal times for the problems of finite and infinite horizon . The approach used in non standard analysis is that of the Internal Set Theory.Keywords: optimal-stopping problem, finite and infinite horizon, Internal Set Theory, quasi-optimal time, optimal time, Loeb-Nelson integrability.
  • Ítem
    Scenario development, qualitative causal analysis and system dynamics
    (2009-02-18 00:00:00) Ruge, Michael H.; Kessler, Howard; Singh, Ajit; Hejazi, Shahram
    The aim of this article is to demonstrate that technology assessments can be supported by methods such as scenario modeling and qualitative causal analysis. At Siemens, these techniques are used to develop preliminary purely qualitative models. These or parts of these comprehensive models may be extended to system dynamics models.While it is currently not possible to automatically generate a system dynamics models (or vice versa, obtain a qualitative simulation model from a system dynamics model), the two thechniques scenario development and qualitative causal analysis provide valuable indications on how to proceed towards a system dynamics model. For the qualitative analysis phase, the Siemens – proprietary prototype Computer – Aided Technology Assessment Software (CATS) supportes complete cycle and submodel analysis.Keywords: Health care, telecommucations, qualitative model, sensitivity analysis, system dynamics.
  • Ítem
    Modelos aditivos y multiplicativos en el análisis de matrices multitrazos - multimétodos de cuestionarios de intereses profesionales
    (2009-02-18 00:00:00) Ruhel, Jacques; Marivain, Thierry
    The psychologist needs the evaluation of the conceptual validity (convergent and discriminant) of psychological constructions, used for describing and explaining the organization of his observations. In this work, we describe two approaches based in latent variables, that can be used for these evaluations. The first one is the first order confirmatory (or restrictive) factor analysis; the second one is the direc´-product model where the traits and the methods take effect. The methods are used on a data matrix multitrait and multimethod take effect. The methods are used on a data matrix   multitrait and multimethod obtained on a sample of 189 french high-school students, that responded two questionnaires of  professional interests; a discussion of the results follows.Keywords: conceptual validity, multitrait-multimethod matrices, confirmatoty factor analysis, direct- product model, professional interest.
  • Ítem
    La factorización de una transformada de Fourier en el método de Wiener-Hopf
    (2009-02-18 00:00:00) Rosales Ortega, José; Márquez Rivera, Carlos
    Using the Wiener-Hopf method, we factorize the Fourier Transform of the kernel of a singular integral equation as the product of two functions: one holomorphic in the upper semiplan and the other holomophic in the lower semiplan.Keywords: function product, Fourier transform, Wiener-Hopf method.
  • Ítem
    Sobre la convexidad de la función de presión en el problema de la filtración no lineal
    (2009-02-18 00:00:00) Grebenev, Vladimir N
    We prove the convexity of the pressure function v for the isotropic ideal gaz flow, based on the theorem about the zeros of the solution of the parabolic equation (1)Keywords: fluid mechanics, turbulence, parabolic equation
  • Ítem
    El "unravelling" para bigráficas diferenciales
    (2009-02-18 00:00:00) Boza Cordero, Juan
    Here are examined the main properties of the algorithm called ¨unravelling¨ for differential  bigraphs. This algorithm was originally developed for differential graded categories and was useful in the proof the celebrated ¨tame-wild¨ theorem of ¨Drozd´s. First we describe the algorithm, and then we establish in detail the existence of an equivalence between certain subcategories of representations of the original and the derived bigraphs. We also exhibit the precise behaviour of the norm and the quadratic form under the algorithm.Keywords: representation, differential bigraphic, unravelling, quadratic form, equivalence.