Editorial

Este año se ha caracterizado por la enorme publicidad hecha a las celebraciones del bicentenario de la Independencia y del centenario de la revolución mexicanas. Incluso en muchas publicaciones se ha discutido desde antes sobre la naturaleza misma de los eventos que se pretenden rememorar y han aparecido análisis contrastantes entre sí y muchas veces con las visiones que ofrece la historia oficial

Dynamic analysis of runout correction in milling

Tool runout and its effects is an important area of research within modelling, simulation, and control of milling forces. Tool runout causes tool cutting edges to experience uneven forces during milling. This fact also affects tool life and deteriorates workpiece surface quality. In this article a procedure, in order to diminish the effects of tool runout, is presented. The procedure is based on chip thickness modification by means of the fast correction of the tool feed rate. Dynamic feed rate modification is provided by superposing our own design of a fast feed system driven by a piezoelectric actuator to the conventional feed drive of the CNC machine tool. Previously, a model of the dynamic behaviour of the system was developed to analyze the influence of fast feed rate modification on cutting forces. The model incorporates the piezoelectric actuator response as well as the structural dynamics of the tool and the designed Fast Feed Drive System (FFDS). Simulated and experimental results presented in this paper show the effectiveness and benefits of this new tool runout correction procedure

Weight distribution of cyclic codes defined by quadratic forms and related curves

We consider cyclic codes CL associated to quadratic trace forms inm variables (Formula Presented) determined by a family L of q-linearized polynomials R over Fqm, and three related codes CL,0, CL,1, and CL,2. We describe the spectra for all these codes when L is an even rank family, in terms of the distribution of ranks of the forms QR in the family L, and we also computethe complete weight enumerator for CL. In particular, considering the family L = ‹xql›, with l fixed in N, we give the weight distribution of four parametrized families of cyclic codes Cl, Cl,0,Cl,1, and Cl,2 over Fq with zeros(Formula Presented) respectively,where q = ps with p prime, α is a generator of F*qm, and m/(m,l)is even. Finally, we give simple necessary and sufficient conditions for Artin–Schreier curves yp−y = xR(x)+βx, p prime, associated to polynomials R ∈ L to be optimal. We then obtain several maximal and minimal such curves inthe case (Formula Presented).Fil: Podesta, Ricardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Videla Guzman, Denis Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin

The weight distribution of irreducible cyclic codes associated with decomposable generalized Paley graphs

We use known characterizations of generalized Paley graphs which areCartesian decomposable to explicitly compute the spectra of the corresponding associated irreducible cyclic codes. As applications, we give reduction formulas forthe number of rational points in Artin-Schreier curves defined over extension fields and to the computation of Gaussian periods.Fil: Podesta, Ricardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Videla Guzman, Denis Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin

Uranium and phosphate behaviour in the vadose zone of a fertilised corn field

Phosphate fertilizers contain approximately 200 mg.kg–1 of uranium. The uranium and phosphate can move through the vadose zone and reach groundwater. Therefore, the knowledge of the ways in which these two elements are distributed, their partition relationships and their mobility behavior is of great interest. In order to study the latter, suction cup samplers, intended to collect soil water at different depths, were installed in an experimental site in a high plain of Mexico, where corn is cultivated and phosphate fertilizers are systematically applied. It was observed that the vadose zone contains high concentrations of uranium (1–50 mg.k –1) and phosphates (22–33 mg.kg–1), which decrease at greater depths. Uranium concentration in the soil water varies between 10 and 3 mg.l–1 and phosphates between 1 and 0.3 mg.l–1. Their evolution throughout the profile of the vadose zone is determined by the decrease in concentrations, due to the physico-chemical processes involved

El espectro de códigos cíclicos y grafos asociados

Una de las clases más importantes e implementadas de códigos, es la clase de los códigos cíclicos, debido a su eficiente codificación, y por la existencia de buenos algoritmos para decodificarlos. Por otro lado, entender la distribución de pesos de códigos permite en algunos casos, calcular el error de probabilidad a la hora de decodificar. Por ello, es importante conocer la distribución de pesos de códigos cíclicos. En general, el problema de calcular distribuciones de pesos es computacionalmente complejo, inclusive en el caso de códigos cíclicos. Sin embargo, es posible atacar este problema si pedimos ciertas condiciones al código cíclico. Esta tesis se centra en el estudio del espectro o distribución de pesos de códigos cíclicos, y de las distintas relaciones que tienen estos espectros con otros objetos que aparecen en el estudio de cuerpos finitos tales como sumas exponenciales, caracteres, curvas algebraicas y grafos de Cayley