Troqueladora manual de platina

En aquest projecte final de carrera s’ha estudiat el mercat de les màquines encunyadores o troqueladores de la indústria de les arts gràfiques. S’ha projectat una màquina roqueladora amb càrrega i descàrrega manual de material. S’han estudiat els tipus de màquines que hi ha al mercat per projectar una alternativa a la maquinaria actual. S’ha recollit informació sobre premses en general i sobre troqueladores d’arts gràfiques en particular. Amb la visió global que dóna l’estudi, s’ha arribat a una alternativa viable que ha esdevingut en nucli del projecte en la seva etapa de desenvolupament. S’ha realitzat un estudi cinemàtic i dinàmic del mecanisme de la màquina projectada. A la memòria es recull l’evolució de tot el procés de projecte des de les primeres fases d’estudi fins a entrar en el projecte de la solució concreta. Es justifiquen les decisions preses avaluant les alternatives que s’hi presenten per arribar a aquesta solució escollida. Es mostren les figures tridimensionals de la gran majoria de components existents a la màquina projectada. A un dels annexos es recullen els dibuixos de conjunt i de peça dels elements més característics del projecte mecànic. L’annex de càlculs recull la informació del procés cinemàtic i dinàmic en la primera part. Posteriorment es centra en la selecció de l’accionament de la màquina i dels elements mecànics més característics. L’annex d’estudi econòmic indica que és viable obtenir un benefici industrial de la màquina projectada. Es calculen els costos directes des del projecte de màquina fins als derivats de la seva execució

Fatigue crack initiation and growth on a steel in the very high cycle regime with sea water corrosion

The authors acknowledge Arts et Métiers ParisTech and Foundation Arts et Métiers for the financial support of P.C. Paris’ stay at LAMEFIP. They acknowledge Vicinay Cadenas S.A. for its financial support, and both the PCP France-Mexique and the CONACYT for their financial support too.This paper is devoted to the effect of corrosion on the gigacycle fatigue strength of a martensitic–bainitic hot rolled steel used for manufacturing offshore mooring chains for petroleum platforms. Smooth specimens were tested under fully reversed tension between 1E6 and 1E10 cycles in three testing conditions and environments: (i) in air, (ii) in air after precorrosion and (iii) in air under real time artificial sea water flow. The fatigue strength at greater than 108 cycles is reduced by a factor more than five compared with non-corroded specimens. Fatigue cracks initiate at corrosion pits due to pre-corrosion, if any, or pits resulting from corrosion in real time during the cyclic loading. It is shown that under sea water flow, the fatigue life in the gigacycle regime is mainly governed by the corrosion process. Furthermore, the calculation of the mode I stress intensity factor at hemispherical surface defects (pits) combined with the Paris–Hertzberg–Mc Clintock crack growth rate model shows that fatigue crack initiation regime represents most of the fatigue life.PCP France Mexique, Conacyt, Arts et Métiers ParisTech (professeur invité Paul C Paris

Efectos de una enseñanza basada en proyectos sobre el rendimiento en Estadística en estudiantes de Ingeniería

El propósito de este trabajo es proporcionar información sobre el rendimiento académico en Estadística de los estudiantes de la Facultad de Ingeniería de la Universidad Nacional de Mar del Plata, al aplicar una enseñanza basada en proyectos de análisis de datos. Se midió a partir de las respuestas al cuestionario de Konold y Garfield (1993), dadas por alumnos de la asignatura Estadística Básica. Los resultados mostraron un mejor rendimiento académico en los alumnos que recibieron una experiencia didáctica con carácter innovador, que considera un aprendizaje significativo orientado a las competencias.Fil: Figueroa, Stella M. Universidad Nacional de Mar del Plata; ArgentinaFil: Ledesma, Ruben Daniel. Universidad Nacional de Mar del Plata. Facultad de Psicología. Introducción a la Investigación Psicológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata; ArgentinaFil: Pérez, María Angélica. Universidad Nacional de Tucumán. Facultad de Ciencias Económicas; Argentin

The bacterial community composition of the surface microlayer in a high mountain lake

The existence of bacterioneuston in aquatic ecosystems is well established, but little is known about its composition and dynamics, particularly in lakes. The bacterioneuston underlies extreme conditions at the air-water boundary, which may influence its dynamics in a different way compared with the bacterioplankton. In this study, we assessed quantitative changes in major bacterial groups of the surface microlayer (SML) (upper 900 μm) and the underlying water (ULW) (0.2-0.5 m depth) of an alpine lake during two consecutive ice-free seasons. Analysis of the bacterial community composition was done using catalyzed reporter deposition FISH with oligonucleotide probes. In addition, several physicochemical parameters were measured to characterize these two water layers. Dissolved organic carbon was consistently enriched in the SML and the dissolved organic matter pool presented clear signals of photodegradation and photobleaching. The water temperature was generally colder in the SML than in the subsurface. The bacterial community of the SML and the ULW was dominated by Betaproteobacteria and Actinobacteria. The bacterial community composition was associated with different combinations of physicochemical factors in these two layers, but temporal changes showed similar trends in both layers over the two seasons. Our results identify the SML of alpine lakes as a microhabitat where specific bacterial members such as of Betaproteobacteria seem to be efficient colonizer

Hybridisable Discontinuous Galerkin Formulation of Compressible Flows

This work presents a review of high-order hybridisable discontinuous Galerkin (HDG) methods in the context of compressible flows. Moreover, an original unified framework for the derivation of Riemann solvers in hybridised formulations is proposed. This framework includes, for the first time in an HDG context, the HLL and HLLEM Riemann solvers as well as the traditional Lax-Friedrichs and Roe solvers. HLL-type Riemann solvers demonstrate their superiority with respect to Roe in supersonic cases due to their positivity preserving properties. In addition, HLLEM specifically outstands in the approximation of boundary layers because of its shear preservation, which confers it an increased accuracy with respect to HLL and Lax-Friedrichs. A comprehensive set of relevant numerical benchmarks of viscous and inviscid compressible flows is presented. The test cases are used to evaluate the competitiveness of the resulting high-order HDG scheme with the aforementioned Riemann solvers and equipped with a shock treatment technique based on artificial viscosity.Comment: 60 pages, 31 figures. arXiv admin note: substantial text overlap with arXiv:1912.0004

Anatomy of corpus callosum in prenatally malnourished rats

Indexación: Web of Science; ScieloThe effect of prenatal malnutrition on the anatomy of the corpus callosum was assessed in adult rats (45-52 days old). In the prenatally malnourished animals we observed a significant reduction of the corpus callosum total area, partial areas, and perimeter, as compared with normal animals. In addition, the splenium of corpus callosum (posterior fifth) showed a significant decrease of fiber diameters in the myelinated fibers without changing density. There was also a significant decrease in diameter and a significant increase in density of unmyelinated fibers. Measurements of perimeter's fractal dimensions from sagittal sections of the brain and corpus callosum did not show significant differences between malnourished and control animals. These findings indicate that cortico-cortical connections are vulnerable to the prenatal malnutrition, and suggest this may affect interhemispheric conduction velocity, particulary in visual connections (splenium).http://ref.scielo.org/nph4s

Evolución de la literatura occidental desde un contexto sociológico. De la Grecia clásica al Barroco

Hablar de literatura es hacer mención a una de las más especiales características del ser humano. Ese esfuerzo por transmitir hacia afuera todo lo que nuestra actividad cerebral genera, ha ido desarrollándose a lo largo de la historia en un proceso lento pero necesario para su avance. El lenguaje oral necesitaba de un recipiente dónde contener las palabras que de otra manera hubiesen quedado derramadas en el aire a perpetuidad. Con la aparición de la escritura surgirá la memoria documental, el registro material y no mental de las cosas y, con ella, la literatura como aquello que contiene a las letras. La literatura con el paso del tiempo ha ido sufriendo notables modificaciones tanto en el significado, como en los estilos, así como en su uso social. Se pretende hacer un análisis sociológico de la evolución de la literatura occidental hasta el siglo XVII, antes del acontecer de la literatura moderna

Characterization of Neurospora crassa α-Actinin

α-Actinin, an actin-binding protein of the spectrin superfamily, is present in most eukaryotes except plants. It is composed of three domains: N-terminal CH-domains, C-terminal calcium-binding domain (with EF-hand motifs), and a central rod domain. We have cloned and expressed Neurospora crassa α-actinin as GST and GFP fusion proteins for biochemical characterization and in vivo localization, respectively. The intracellular localization pattern of α-actinin suggests that this protein is intimately associated with actin filaments and plays an important role in the processes of germination, hyphal elongation, septum formation, and conidiation. These functions were confirmed by the experiments on the effect of α-actinin gene deletion in N. crass