Efecto de la Corriente y Longitud de Arco en Soldaduras con Arco Eléctrico Asistido por Modelado Matemático

A 2D mathematical model was developed for the GTAW arc welding process (Gas Tungsten Arc Welding). Computational simulations were performed by using the commercial software PHOENICS based on mass and momentum conservation equations as well as on Maxwell equations. The model predicts the electric characteristics of the arc column, flow patterns, temperature profiles, heat flux, total heat flow and the electrical potential, by varying the arc length and the applied current. By increasing the current the arc jet is stronger, hotter and provides more heat to the weld pool, while by increasing the arc length the maximum temperature, maximum velocity and heat flow are unchanged, although a short arc focuses the heat in a small area and a long arc spreads the heat in a wider area of the work piece.Keywords: Electric arc, heat transfer, fluid flow, mathematical modeling.

Evaluating the Effectiveness and Motivational Impact of Replacing a Human Instructor by Mobile Devices for Teaching Network Services Configuration to Telecommunication Engineering Students

Proceedings of: 10th IEEE International Conference on Advanced Learning Technologies (ICALT 2010). Sousse, Tunisia, 5-7 July 2010.The introduction of mobile technologies in class provide instructors with tools for contextualized, active, situated, any-time any-where learning. In fact, the role of the instructor can be partially delegated to the student by the use of a mobile device. This paper assesses if this delegation can be brought to the limit of eliminating the need of the physical presence of the instructor in the particular context of a situated learning environment consisting of a server room where third year Telecommunication Engineering students learn how to configure network services such as DNS, SMTP and HTTP. The paper presents the results of two experiments inside the "advanced telematic applications" course at the Carlos III University of Madrid. Two groups of students participated in the experiments, one following traditional instructor based classes and the other using NFC enabled mobile phones. The paper analyzes both learning increments and motivational aspects.The work presented in this paper has been partially funded by the project Learn3 TIN2008-05163/TSI within the Spanish “Plan Nacional de I+D+I”, the SOLITE CYTED Program 508AC0341 and the e-Madrid project S2009/TIC-1650 funded by the Madrid regional Government. Thanks to INNOVISION for providing the NFC tags for this experiment. Gustavo Ramirez-Gonzalez is funded by the EU Programme Alban, scholarship number E06D101768CO and by the Universidad del Cauca.Publicad

Effect of Defoliation Frequency and Planting Density on Yield and Nutritive Value of \u3ci\u3eCoursetia ferruginea\u3c/i\u3e (HBK) Lavin

The aim of the present study was to asses the influence of the frequency of defoliation and density of sowing on yield and nutritive value of Coursetia ferruginea. Three defoliation frequencies (6, 8 and 10 weeks) and three densities of planting (1 x 1 m, 1 x 1.5 m and 1 x 2 m) were evaluated. A randomized block design, in a split plot arrangement and four repetitions, was used. Frequency of defoliation has a strong significant (P\u3c 0.01) effect on dry matter (DM) yield (13.6, 18.1 and 27.8 g DM/plant for 6, 8 and 10-week defoliation frequencies), plant height (63.5, 76.6 and 101.2 cm) and plant survival (71, 74 and 86%). Nutritive value was significantly (P\u3c 0.05) affected by the frequency of defoliation. Mineral content was reduced as the defoliation interval increased. Density of planting did not affect (P\u3e 0.05) any of the variables. It is concluded that, C. ferruginea is a forage shrub with potential to improve animal feed quality, but it does not stand frequent defoliation

Efecto de las altas presiones hidrostáticas y el tratamiento térmico tradicional en las características físicoquímicas, microbiológicas y análisis sensorial de una mermelada de aceituna

In the present work the effect of the processing by high hydrostatic pressures (HPP) was assessed as an alternative to the thermal treatment of pasteurization in olive jam. The effects of both treatments on the product after processing were compared and stability during storage under refrigeration was assessed through the characterization of physicochemical, microbiological and sensory aspects. To assess the effect of processing, two HPP treatments (450 and 600MPa) and thermal pasteurization (80 °C for 20 min) were applied, comparing them with the unprocessed product. HPP 600MPa versus the rest of treatments showed a reduction in microorganisms, greater clarity and less browning, and sensory acceptance. The shelf-life of the refrigerated product would indicate the feasibility of the application of the HPP technology for food with similar shelf-life to that obtained with the traditional treatment of pasteurization, but with a better sensory quality.En el presente trabajo se valoró el efecto del procesado por altas presiones hidrostáticas (HPP) como método alternativo al tratamiento térmico de pasteurización en la mermelada de aceitunas. Para ello se comparó el efecto de ambos tratamientos sobre el producto procesado y se evaluó su estabilidad durante el almacenamiento en refrigeración, mediante la caracterización de los aspectos físico-químicos, microbiológicos, y sensoriales. Para evaluar el efecto del procesado, se aplicaron dos tratamientos de HPP (450 y 600MPa) y otro de pasteurización térmica (80 °C durante 20 min), comparándose con el producto no procesado. Las muestras tratadas con HPP 600MPa presentaron, frente al resto de tratamientos una reducción en la presencia de microorganismos, mayor claridad y menor pardeamiento, y una mayor aceptación sensorial. El estudio de la vida útil del producto en refrigeración, indicaría la viabilidad de la aplicación de la tecnología de HPP para obtener alimentos con vida útil similar a la obtenida con el tratamiento tradicional de pasteurización, pero con mejor calidad sensorial

InterEvo-TR: Interactive Evolutionary Test Generation With Readability Assessment

Automated test case generation has proven to be useful to reduce the usually high expenses of software testing. However, several studies have also noted the skepticism of testers regarding the comprehension of generated test suites when compared to manually designed ones. This fact suggests that involving testers in the test generation process could be helpful to increase their acceptance of automatically-produced test suites. In this paper, we propose incorporating interactive readability assessments made by a tester into EvoSuite, a widely-known evolutionary test generation tool. Our approach, InterEvo-TR, interacts with the tester at different moments during the search and shows different test cases covering the same coverage target for their subjective evaluation. The design of such an interactive approach involves a schedule of interaction, a method to diversify the selected targets, a plan to save and handle the readability values, and some mechanisms to customize the level of engagement in the revision, among other aspects. To analyze the potential and practicability of our proposal, we conduct a controlled experiment in which 39 participants, including academics, professional developers, and student collaborators, interact with InterEvo-TR. Our results show that the strategy to select and present intermediate results is effective for the purpose of readability assessment. Furthermore, the participants' actions and responses to a questionnaire allowed us to analyze the aspects influencing test code readability and the benefits and limitations of an interactive approach in the context of test case generation, paving the way for future developments based on interactivity.Comment: 17 pages, 10 figures, 5 tables, journal pape

Interactivity in the Generation of Test Cases with Evolutionary Computation

Test generation is a costly but necessary testing activity to increase the quality of software projects. Automated testing tools based on evolutionary computation principles constitute an appealing modern approach to support testing tasks. However, these tools still find difficulties to detect certain types of plausible faults in real-world projects. Besides, recent studies have shown that, in general, automatically-generated tests do not resemble those manually written and, consequently, testers are reluctant to adopt them. We observe two key issues, namely the opacity of the process and the lack of cooperation with the tester, currently hampering the acceptance of automated results. Based on these findings, we explore in this paper how the interaction between current tools and expert testers would help address the test case generation problem. More specifically, we identify a number of interaction opportunities related to the object-oriented test case design driven to boost their readability and detection power. Using EvoSuite as base implementation, we present a proof of concept focused on the possibility to integrate readability assessment of the most promising test suites into a genetic algorithm.Work partially funded by the European Commission (ERDF), the Spanish Ministry of Science, Innovation and Universities [RTI2018-093608-BC33 and RED2018-102472-T], the University of Cordoba (Plan Propio - mod. 2.4), and the University of Malag

Root Density in \u3cem\u3ePanicum maximum\u3c/em\u3e cv. Tanzania Monoculture and in a Mixture with \u3cem\u3eLeucaena leucocephala\u3c/em\u3e with Different Densities in Mexico

In Yucatan cattle production is limited by forage availability during the dry season. L. leucocephala has good nutritive value (24 - 30% CP) and can stand drought and grazing, therefore its use in mixture with grasses is recommended. However, in association both species could compete for light, water and nutrients. The aim of this study was to assess the effect of introduction of L. leucocephala with different densities on root density of P. maximum

Multifunctional Nanomaterials for Biofortification and Protection of Tomato Plants

Calcium phosphate nanoparticles were doped with zinc ions to produce multifunctional nanomaterials for efficient agronomic fortification and protection of plants. The resulting round-shaped nanoparticles (nanoZn) were composed of 20.3 wt % Ca, 14.8 wt % P, and 13.4 wt % Zn and showed a pH-controlled solubility. NanoZn were stable in aqueous solutions at neutral pH but dissolved in citric acid at pH 4.5 (i.e., the pH inside tomato fruits), producing a pH-responsive delivery of the essential nutrients Ca, P, and Zn. In fact, the foliar application of nanoZn on tomato plants provided tomatoes with the highest Zn, Ca, and P contents (causing, respectively, a 65, 65, and 15% increase with respect to a conventional treatment with ZnSO4) and the highest yields. Additionally, nanoZn (100 ppm of Zn) inhibited in vitro the growth of Pseudomonas syringae (Ps), the main cause of bacterial speck, and significantly reduced Ps incidence and mortality in tomato seeds, previously inoculated with the pathogen. Therefore, nanoZn present dual agricultural applicability, enriching crops with nutrients with important metabolic functions in humans and simultaneously protecting the plants against important bacterial-based diseases, with considerable negative impact in crop productionJunta de Andalucía through the project NanoFERTI (P18-TP- 969)Projects NanoFERTI2 (CPP2021-008801)NextGenerationEU/PRTRRYC2021-032734-I funded by MCIN/AEI/10.13039/501100011033European Union NextGenerationEU/PRT

Evaluation and implementation of measurement uncertainty for determining stationary source emissions: a review

Este artículo presenta una revisión de metodologías comúnmente citadas en la literatura para la estimación de la incertidumbre, como es la metodología no estocástica de la Guía para la Expresión de la Incertidumbre de Medida (GUM), la cual provee una estructura de estimación con limitaciones en su implementación, como son: cálculo de derivadas parciales, suposición de linealidad de los modelos e identificación de las fuentes de incertidumbre y sus distribuciones de probabilidad. Por otro lado, se discuten otros métodos para estimar la incertidumbre, como son: Monte Carlo, Conjuntos Difusos, Intervalo Generalizado, Inferencia Bayesiana, Caos Polinomial y Bootstrap, que a diferencia de la GUM, presentan limitaciones de costo computacional y requieren de conocimientos más especializados para su implementación. El objetivo de este artículo es reportar el grado de aplicación y difusión de los métodos de estimación de la incertidumbre en las emisiones de fuentes fijas, encontrándose que la mayoría se enfoca en estudios usados para la elaboración de inventarios de gases de efecto invernadero (GHG), y son escasos los orientados a la medición de las emisiones de fuentes fijas usando monitoreos de lectura directa, como también los métodos definidos por la Agencia de Protección Ambiental de los Estados Unidos (US EPA). Se discute finalmente las fortalezas y debilidades que dan lugar al fomento de nuevas investigaciones en esta área del conocimiento.This paper presents a review of commonly-cited methods for estimating uncertainty in the literature. One of them is the non-stochastic approach proposed by the Guide to the Expression of Uncertainty in Measurement (GUM), which provides an estimation framework with limitations for the implementation, such as computation of partial derivatives, linear model assumptions, and uncertainty source identification with probability distributions. Other methods to estimate uncertainty are discussed as well; they include Monte Carlo, Fuzzy Sets, Generalized Intervals, Bayesian Inference, Polynomial Chaos, and Bootstrap, which in contrast to GUM present limitations regarding computational cost and require more specialized knowledge to be implemented. The aim of this work is to report the level of application and dissemination of methods for estimating the uncertainty of emissions caused by stationary sources. Most of the works in this field were found to be focused on the creation of inventories of Greenhouse Gases (GHG), and very few of them on the uncertainty associated with measuring the emissions of stationary sources using direct reading monitoring or those defined by the Environmental Protection Agency of the United States (US EPA). Finally, strengths and weaknesses are discussed in order to promote new research in this knowledge area