Scheduling for Optimal Rate Allocation in Ad Hoc Networks With Heterogeneous Delay Constraints

This paper studies the problem of scheduling in single-hop wireless networks with real-time traffic, where every packet arrival has an associated deadline and a minimum fraction of packets must be transmitted before the end of the deadline. Using optimization and stochastic network theory we propose a framework to model the quality of service (QoS) requirements under delay constraints. The model allows for fairly general arrival models with heterogeneous constraints. The framework results in an optimal scheduling algorithm which fairly allocates data rates to all flows while meeting long-term delay demands. We also prove that under a simplified scenario our solution translates into a greedy strategy that makes optimal decisions with low complexity

Real-time portable system for fabric defect detection using an ARM processor

Modern textile industry seeks to produce textiles as little defective as possible since the presence of defects can decrease the final price of products from 45% to 65%. Automated visual inspection (AVI) systems, based on image analysis, have become an important alternative for replacing traditional inspections methods that involve human tasks. An AVI system gives the advantage of repeatability when implemented within defined constrains, offering more objective and reliable results for particular tasks than human inspection. Costs of automated inspection systems development can be reduced using modular solutions with embedded systems, in which an important advantage is the low energy consumption. Among the possibilities for developing embedded systems, the ARM processor has been explored for acquisition, monitoring and simple signal processing tasks. In a recent approach we have explored the use of the ARM processor for defects detection by implementing the wavelet transform. However, the computation speed of the preprocessing was not yet sufficient for real time applications. In this approach we significantly improve the preprocessing speed of the algorithm, by optimizing matrix operations, such that it is adequate for a real time application. The system was tested for defect detection using different defect types. The paper is focused in giving a detailed description of the basis of the algorithm implementation, such that other algorithms may use of the ARM operations for fast implementations

Structural Evaluation of Bamboo Bike Frames: Experimental and Numerical Analysis

Construction of bicycles with bamboo frames has become an alternative to improve the quality of life of some communities, be friendly with the environment and be ecologically sustainable. However, the production of bike frames is made in an artisanal way and there are few antecedents that have proven their reliability. This work presents the evaluation and simulation of the mechanical behavior of bike frames made in bamboo. Three-points bending tests were performed using bamboo bars with similar dimensions to bike frames, and an equivalent elasticity modulus was determined and used as the input datum of a finite element model. A linear model material and beam elements were used to model the bike frame. Tests were performed using bike frames of bamboo applying loads greater than 7000 N, and the displacements were measured. The experimental displacements were used to calibrate the model, which consisted of modifying the rigidity of the connections until the displacements of the model fit near to 90%. The calibrated model was used for a fatigue simulation in order to predict the lifespan of the bike frame. Some technical values of bamboo bike frames were obtained so that these will allow them to define the technical characteristics of the product and guarantee their operating conditions

Influencia de la potencia de deposición en las propiedades eléctricas y ópticas de películas delgadas de Sn1-xO2 Nbx obtenidas por pulverización catódica

RESUMEN: En un sólido la buena conductividad eléctrica y la transparencia óptica parecen ser 2 propiedades contradictorias. Los materiales conductores son opacos, y los sólidos transparentes son aislantes eléctricos. La combinación de estas dos propiedades en un material lo hacen muy atractivo para una gran cantidad de aplicaciones optoelectrónicas. En este trabajo se realiza la caracterización estructural óptica y eléctrica de uno de los óxidos conductores transparentes más prometedores, el Sn1-xO2 Nbx . Las películas fueron crecidas sobre sustratos de vidrio por la técnica de sputtering RF. Al cambiar la potencia de deposición se halló que la conductividad eléctrica de las películas crecía al aumentar la potencia de deposición, lo cual coincidía con un crecimiento preferencial de las películas en el plano (200). Todas las películas muestran una transmitancia mayor al 80 % en el rango visible.ABSTRACT: In a solid, the electrical conductivity and optical transparency seem to be two contradictory physical properties. Conductive materials are opaque, and transparent solids are electrical insulators. Combinations of these two physical properties in a material make it appropriate for application in many optoelectronic devices. The coincidence of these two properties has been mainly ascribed to point defects in the crystal lattice. In this work, we performed structural, electrical and optical characterization of thin films of one of the most promising transparent conductive oxides Sn1-xO2 Nbx . The films were grown on glass substrates by RF magnetron sputtering technique. As the deposition power was varied, it was found that the electrical conductivity of the films increased with increasing power deposition, and they showed a preferential growth in the (200) direction. All films exhibited optical transmittance in the visible range larger than 80%

Herramientas de modelado para Bioingeniería, casos de estudio: a) Antena de relajometría por Resonancia Magnética, b) Bobina generadora de gradientes magnéticos

En el campo de la imagenología, clínica, la resolución y el contraste de imágenes médicas es el reto a obtener por los radiólogo en cada estudio o adquisición obtenida, aunque existen diversas técnicas de software que ayudan a apreciar de manera favorable estos conceptos, su potenciación es determinada por la tecnología del equipo y la intensidad de su campo magnético, este último concepto asociado para la técnica de Resonancia Magnética Nuclear. En la actualidad existe un método alternativo, que permite observar de manera eficaz ciertas regiones o secciones anatómicas diana, y con una mayor claridad visual que las técnicas actualmente en uso, es a través del uso de agentes de contraste, como ejemplo el Gadolinio, que permite potenciar y resaltar en intensidad, las secciones anatómicas que fueron programadas para su estudio. Para su uso, los agentes de contraste deberán ser evaluados en un equipo de relojometría de ciclado rápido por resonancia magnética, que tiene la función de obtener los valores T1 y T2, tiempos de relajación del elemento. El objetivo del presente trabajo de investigación, es un estudio de las diferentes herramientas de software de simulación involucradas en el análisis de los elementos transceptores, del equipo de relajometría de ciclado rápido por RM (Resonancia Magnética), elemento que tiene como función obtener los vectores de magnetización transversal y longitudinal de la muestra de gadolinio, así como la bobina generadora de gradientes de campo magnético, para entender el comportamientos de las nanopartículas ante las variaciones de campo electromagnético

Benchmarking seeding strategies for spreading processes in social networks: an interplay between infuencers, topologies and sizes

The explosion of network science has permitted an understanding of how the structure of social networks affects the dynamics of social contagion. In community-based interventions with spill-over effects, identifying influential spreaders may be harnessed to increase the spreading efficiency of social contagion, in terms of time needed to spread all the largest connected component of the network. Several strategies have been proved to be efficient using only data and simulation-based models in specific network topologies without a consensus of an overall result. Hence, the purpose of this paper is to benchmark the spreading efficiency of seeding strategies related to network structural properties and sizes. We simulate spreading processes on empirical and simulated social networks within a wide range of densities, clustering coefficients, and sizes. We also propose three new decentralized seeding strategies that are structurally different from well-known strategies: community hubs, ambassadors, and random hubs. We observe that the efficiency ranking of strategies varies with the network structure. In general, for sparse networks with community structure, decentralized influencers are suitable for increasing the spreading efficiency. By contrast, when the networks are denser, centralized influencers outperform. These results provide a framework for selecting efficient strategies according to different contexts in which social networks emerge

Gingivoplastía con láser de diodo de alta intensidad por agrandamiento gingival

   The article reports the case of a 53-year-old male patient, who went to the Clinic of University Dental Services (SERODU), in Ecuador, for presenting a gingival smile. He had no relevant medical history. He was diagnosed with a gingival enlargement of teeth 1.1, 1.2 and 2.1 and was treated with high intensity diode laser gingivoplasty. After 15 days of control, good healing was observed and the patient stated that he had no postoperative pain.The objective of this clinical case is to show the benefits of the high intensity diode laser, for the treatment of gingival enlargement and thereby achieve a better aesthetic perception of the upper anterior teeth.    El articulo reporta el caso de un paciente masculino de 53 años de edad, quien acudió a la Clínica de Servicios Odontológicos Universitarios (SERODU), en Ecuador, por presentar sonrisa gingival. No presentaba antecedentes médicos relevantes. Se le diagnosticó agrandamiento gingival, de las piezas dentarias 1.1,1.2 y 2.1 y fue tratado con gingivoplastía con láser de alta intensidad de diodo. A los 15 días de control se observó una buena cicatrización y el paciente manifestó no haber tenido dolor posoperatorio.El objetivo de este caso clínico, es mostrar los beneficios del láser de diodo de alta intensidad, para el tratamiento del  agrandamiento gingival y con ello lograr una mejor percepción estética de los dientes antero superiores.

Análisis de los cuellos de botella en la logística internacional de las PYMES de confecciones en Colombia.

Análisis de los cuellos de botella en la logistica internacional de las pymes de confecciones en Colombia. Se realiza un analisis de la situacion actual de la logistica nacional enfocada a las pymes de confeccion en Colombia, realizando un comparativo con el mercado mundial, se evaluan opciones de mejoramiento y su implementacion en el mercado de la confeccion nacional.Analysis of bottlenecks in the international logistics of clothing SMEs in Colombia. An analysis of the current situation of the national logistics focused on clothing SMEs in Colombia is carried out, making a comparison with the world market, improvement options and their implementation in the national clothing market are evaluated

Exports and Productivity: Comparable Evidence for 14 Countries

We use comparable micro level panel data for 14 countries and a set of identically specified empirical models to investigate the relationship between exports and productivity. Our overall results are in line with the big picture that is by now familiar from the literature: Exporters are more productive than non-exporters when observed and unobserved heterogeneity are controlled for, and these exporter productivity premia tend to increase with the share of exports in total sales; there is strong evidence in favour of self-selection of more productive firms into export markets, but nearly no evidence in favour of the learning-by-exporting hypothesis. We document that the exporter premia differ considerably across countries in identically specified empirical models. In a meta-analysis of our results we find that countries that are more open and have more effective government report higher productivity premia. However, the level of development per se does not appear to be an explanation for the observed cross-country differences.exports; productivity; micro data; international comparison