Model of a continuous crystallization process for a sorbet by the moments methodology

La etapa de precongelación es un importante paso en el proceso de manufactura de helados y sorbetes dado que las condiciones de operación tienen una fuerte influencia sobre la microestructura y por consecuencia sobre los atributos sensoriales del producto final. Esta etapa de precongelación es llevada a cabo en un intercambiador de calor de superficie raspada donde la calidad del producto es fuertemente influenciada por las condiciones de operación tales como la temperatura de evaporación de un refrigerante, el gasto másico de la alimentación, la velocidad del raspador y una presión provocada por la introducción de aire. Con la finalidad de estudiar la pertinencia de un sistema de control basado en la influencia de las variables del proceso sobre la calidad del producto, este trabajo presenta un modelo para una cristalización continua de un sorbete utilizando la metodología de momentos, el cual es validado con datos experimentales. El modelo realizado por esta metodología de momentos es capaz de representar la influencia de las condiciones de operación durante la cristalización de sorbete sobre las características finales del producto tales como el tamaño de cristal y la temperatura de salida del intercambiador de superficie raspada (ICSR) en ausencia de aire. El modelo basado en momentos se estudia, entonces, como la reducción del modelo de la ecuación de balance de población e incluye los fenómenos de nucleación heterogénea y crecimiento. De este modo, el modelo desarrollado representa requerimientos computacionales mínimos y está altamente adaptado para tareas de optimización y/o control del proceso.Freezing is an important step in the manufacturing process of ice-cream and sorbet, since the operating conditions have a strong influence on the micro-structure, and consequently on the sensorial attributes of the final product. This steep of freezing is carried out by a scraped surface heat exchanger (SSHE) where the product quality is conditioned by process conditions as the evaporation temperature of a refrigerant fluid, the mix flow rate, the dasher speed and the cylinder pressure due to the air introduction. In order to study the relevance of a control system based on the influence of process variables on product quality, this paper presents a model for a continuous crystallization of a sorbet using the method of moments, which is validated by experimental data.The model created by this methodology has been able to represent the influence of the process conditions during the crystallization of the sorbet on the final product characteristics such as crystal size and the draw temperature in the outlet of the SSHE in absence of air. The model based in moments is studied as a reduced model of the population balance equation and includes the phenomena of heterogeneous nucleation and growth. This model developed represents minimal computational requirements and is highly adapted for optimization and/or process control tasks.Peer Reviewe

Tests of Gaussianity

We review two powerful methods to test the Gaussianity of the cosmic microwave background (CMB): one based on the distribution of spherical wavelet coefficients and the other on smooth tests of goodness-of-fit. The spherical wavelet families proposed to analyse the CMB are the Haar and the Mexican Hat ones. The latter is preferred for detecting non-Gaussian homogeneous and isotropic primordial models containing some amount of skewness or kurtosis. Smooth tests of goodness-of-fit have recently been introduced in the field showing some interesting properties. We will discuss the smooth tests of goodness-of-fit developed by Rayner and Best for the univariate as well as for the multivariate analysis.Comment: Proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive), in pres

A recovery-type error estimator for the extended finite element method based on singular+smooth stress field splitting

[EN] A new stress recovery procedure that provides accurate estimations of the discretization error for linear elastic fracture mechanic problems analyzed with the extended finite element method (XFEM) is presented. The procedure is an adaptation of the superconvergent patch recovery (SPR) technique for the XFEM framework. It is based oil three fundamental aspects: (a) the use of a singular+smooth stress field decomposition technique involving the use of different recovery methods (or each field: standard SPR for the smooth field and reconstruction of the recovered singular field using the stress intensity factor K for the singular field: (b) direct calculation of smoothed stresses at integation points using conjoint polynomial enhancement and (c) assembly of patches with elements intersected by the crack using different stress interpolation polynomials at each side of the crack. The method was validated by testing it oil problems with an exact solution in mode I, mode II, and mixed mode and oil it problem without analytical solution. The results obtained showed the accuracy of the proposed error estimator.This paper was developed within the framework of the research projects DP12007-66773-C02-01 and DPI2007-66995-C03-02 of the Ministerio de Educacion y Ciencia (Spain). Funding was also received from the Generalitat Valenciana and the Universidad Politecnica de Valencia.Ródenas, J.; González-Estrada, O.; Taráncón, J.; Fuenmayor, F. (2008). A recovery-type error estimator for the extended finite element method based on singular+smooth stress field splitting. International Journal for Numerical Methods in Engineering. 76(4):545-571. https://doi.org/10.1002/nme.2313S54557176

A note on Poisson goodness-of-fit tests for ionizing radiation induced chromosomal aberration samples

Purpose: To present Poisson exact goodness-of-fit tests as alternatives and complements to the asymptotic u-test, which is the most widely used in cytogenetic biodosimetry, to decide whether a sample of chromosomal aberrations in blood cells comes from an homogeneous or inhomogeneous exposure. Materials and methods: Three Poisson exact goodness-of-fit test from the literature are introduced and implemented in the R environment. A Shiny R Studio application, named GOF Poisson, has been updated for the purpose of giving support to this work. The three exact tests and the u-test are applied in chromosomal aberration data from clinical and accidental radiation exposure patients. Results: It is observed how the u-test is not an appropriate approximation in small samples with small yield of chromosomal aberrations. Tools are provided to compute the three exact tests, which is not as trivial as the implementation of the u-test. Conclusions: Poisson exact goodness-of-fit tests should be considered jointly to the u-test for detecting inhomogeneous exposures in the cytogenetic biodosimetry practice

Influence of endocrine disrupting chemicals on adipogénesis

Indexación: Scopus; Scielo.A raíz del incremento a nivel mundial de la prevalencia de sobrepeso y obesidad tanto en adultos como en niños, con consecuencias en la salud pública, la obesidad se ha convertido en un blanco de estudio de diferentes grupos de investigación, lo que a su vez involucra el entendimiento del proceso de adipogénesis. El proceso de diferenciación de adipocitos es complejo e incluye varios pasos altamente regulados que inducen al fenotipo característico de adipocito maduro, proceso promovido por la activación de los reguladores maestros de las familias de PPARƳ y C/EBPs. La adipogénesis es afectada por diversos factores que incluyen el estado nutricional, mecanismos fisiológicos y también por factores ambientales. Por otra parte, se ha propuesto que diversos contaminantes ambientales, especialmente aquellos con actividades disruptivas endocrinas, están emergiendo como nuevos factores de riesgo para desarrollar obesidad. Químicos disruptores endocrinos son sustancias ambientales que presentan actividad biológica cuyo blanco es la alteración de la función del sistema endocrino, influyendo también en la regulación fisiológica del tejido adiposo. En la presente revisión se expondrán los diferentes disruptores endocrinos a los cuales se les ha comprobado experimentalmente que influyen en la regulación del proceso de adipogénesis.http://www.revistaavft.com/images/revistas/2018/avft_1_2018/influencia_disruptores_endocrinos.pd

Maritime Perspective of Panama Interoceanic Railway

In 1977, when the American historian David McCullough wrote a book called ”The Path Between the Seas: The Creation of the Panama Canal, 1870-1914”, about the social and geographical environment during the Panama Canal construction, he described the transisthmic railway as a complement of the engineering department that French’s company did not know how to take advantage of, because with the Californian gold fever decadence and with the Canal works it would not have had any commercial purpose other than the ridiculous price of passenger tickets. He never imagined that 100 years later this complement will be a key fact in the supply chain of the Latin-American and worldwide trade. In this paper, we will focus in the logistical map of America, where Panama is the centre. Being the way to connect Asia and America, also both coasts of the American Continent, and the begin/end place of four of the five Feeders highways of Latin America, it turns in the link with the others and with the rest of the world. But they are separated by 76 kilometres that a logistical system converts this distance into a one-hour travel to the next connection. The challenges of this system are raising everyday as result of di_erent regional trade facts. The Panamanian complex is playing an important role with the trade balances, the growing economies and transoceanic services with stop in Panama, generating disequilibrium (empty containers problem). The empty containers must follow the empty container cycle since the container is emptied and the customer returns it to the owner, it’s taken to the depot for maintenance, step that is mandatory in order to return to the cycle of export

Is tagging with visual implant elastomer a reliable technique for marking earthworms?

Visual implant elastomer (VIE) has recently been employed to investigate different aspects of earthworm ecology. However, a number of fundamental questions relating to the detection and positioning of the tag, its persistence and potential effects on earthworms remain unknown. Seven earthworm species belonging to three ecological groupings, with different pigmentation and burrowing behaviour, were tagged using different coloured VIE. External inspection after two days, one week and 1, 10 and 27 months were followed by preservation, dissection and internal inspection. Tags could be seen in living specimens to 27 months, and dissection revealed that in most cases they were lodged in the coelomic cavity, held in place by septa. However, over longer time periods (more than two years), the chlorogogenous tissue tended to bind to the tags and made external observation increasingly difficult. Migration of the VIE material towards the posterior of the earthworm and potential loss of the tag were only observed on rare occasions, and a recovery rate in excess of 98% was recorded. By introducing a reasonable amount of VIE into segments, just after the clitellum, this technique can become a valuable tool in earthworm ecology and life history studies, particularly in short-medium term laboratory and field experiments

Primeros datos polínicos de la secuencia "fuentillejo-1" de la laguna del Maar de Fuentillejo (Campo de Calatrava, Ciudad Real)

XV lnternational A.P.L.E. Symposium of Palynolog

Evaluation of ecological organic paint coatings via electrochemical impedance spectroscopy

The behaviour of five different water-based anticorrosive paint systems for the corrosion protection of carbon steel surfaces was evaluated by electrochemical impedance spectroscopy (EIS). Epoxy-polyamine, epoxy-amine and epoxy-acrylic resins as primer coats, and acrylic-polyurethane and acrylic paints as top coats, were investigated both in single layer and double-layer applications. The best protection was provided by the epoxy-amine resin, whereas acrylic-polyurethane exhibited the poorest characteristics and signs of corrosion could be observed since the initial moments of immersion onwards. The impedance spectra could be satisfactorily fitted by employing an equivalent circuit which corresponds to a porous barrier fil