Conformal mapping of ultrasonic crystals: confining ultrasound and cochlear-like wave guiding

Conformal mapping of a slab of a two-dimensional ultrasonic crystal generate a closed geometrical arrangement of ultrasonic scatterers with appealing acoustic properties. This acoustic shell is able to confine ultrasonic modes. Some of these internal resonances can be induced from an external wave source. The mapping of a linear defect produces a wave-guide that exhibits a spatial-frequency selection analogous to that characteristic of a synthetic "cochlea". Both, experimental and theoretical results are reported here.Comment: 4 pages, 4 figure

Monitoreo de Condición en Motores de Combustión Interna Monocilíndricos con Base en Adquisición y Procesamiento de Señales Experimentales

In recent years, condition monitoring based on signal analysis has become a valuable tool for the diagnosis of internal combustion engines. In this paper the experimental design for the ICE monitoring condition, based on signal analysis, is presented. The experimental configuration was development for the analysis of signals from ICE in order to monitor their condition. The conduced case study consists on the monitoring condition of a single-cylinder engine, operating under regular conditions and different speeds. The instrumentation, the adquisition systems as well as the signals analysis are also presented. The adquired signals were: engine block vibration, in-cylinder pressure and crankshaft speed. The mentioned signals were analyzed and processed by FFT and Rigid Regression. It was possible to obtain the frequency spectrum of the vibration signal and reconstruct the in-cylinder pressure of the single-cylinder engine. The presented configuration can be taken as a basis for the evaluation of others engines and for improving the schemes of monitoring condition.Keywords: Internal combustion engines, condition monitoring, signal acquisition, signal processing

SISTEMAS DE INFORMACIÓN Y TOMA DE DECISIONES METODOLOGÍA PARA LA PROGRAMACIÓN DE HORARIOS Y SALONES DE CLASES UNIVERSITARIAS – UN CASO DE ESTUDIO

Universidades, y en general instituciones de educación en todos los niveles, enfrentan en cada periodo académico el problema de la programación de horarios y la asignación de aulas (salones) de clase. En la literatura académica, este problema es una caracterización del problema de timetabling (Hernández et al. 2008). Puesto que existen recursos limitados en infraestructura y medios educativos, el problema consiste en asignar salones (aulas de clases) y recursos (docentes, equipos de apoyo, etc.) a un grupo de clases que deben tomar los estudiantes de acuerdo con su programa de estudios. Otras definiciones recientes del problema se encuentran en los trabajos de Schaerf (1999), Burke y Petrovic (2002) y Pillay (2013). La solución requiere la satisfacción de restricciones fuertes (duras) y suaves. De manera general, se requiere que las clases, módulos o eventos asociados sean programados en espacios horarios de tal forma que, primero, los estudiantes tengan cierta flexibilidad en la escogencia de los cursos; segundo, que los profesores y docentes tengan asignados sus cursos en espacios horarios que les permitan realizar otras actividades (gestión académica, investigación, etc.); y tercero, que la infraestructura sea utilizada de la mejor manera posible. Por esta razón, se invierte mucho tiempo en la planeación y asignación de estos recursos, con el fin de aprovechar al máximo la capacidad instalada. A pesar de los avances en el diseño de procedimientos formales (computacionales) para la resolución del problema, no existe evidencia en la literatura de que estos avances tomen en cuenta restricciones reales o hayan sido efectivamente traducidos en implementaciones reales en las universidades (McCollum 2007). En un estudio realizado hace más de 10 años, Carter y Laporte (1998) manifestaron haberse “sorprendido al descubrir que hay muy pocos artículos sobre planeación o programación de horarios de clases que reportan una real utilización de los métodos empleados en la investigación” [traducción de los autores]. El estudio de McCollum (2007) reporta las mismas conclusiones. 1 Una de las estrategias para reducir este distanciamiento entre los desarrollos teóricos y la implementación real en las universidades de los modelos y algoritmos de programación de horarios consiste en resaltar la importancia de los aspectos particulares de cada institución educativa (McCullan 2007). Bajo esta premisa, el objetivo de este artículo es presentar el impacto que se obtiene al diseñar modelos de optimización apropiados para la programación de horarios en la Universidad de La Sabana, Colombia. Para lograrlo, la siguiente sección presenta en detalle la metodología empleada. Posteriormente se presenta la caracterización del problema, así como los resultados obtenidos. Finalmente, el artículo presenta las conclusiones y algunas líneas para trabajo futuro

Short- and mid-term evaluation of the use of electric vehicles in urban freight transport collaborative networks: a case study

Despite its negative impacts, freight transportation is a primary component of all supply chains. Decision makers have considered diverse strategies, such as Horizontal Collaboration (HC) and the usage of alternative types of vehicles, to reduce overall cost and the related environmental and social impacts. This paper assesses the implementation of an electric fleet of vehicles in urban goods distribution under HC strategy between carriers. A biased randomisation based algorithm is used to solve the problem with a multi-objective function to explore the relationships between both delivery and environmental costs. Real data from the city of Bogota, Colombia are used to validate this approach. Experiments with different costs and demands projections are performed to analyse short- and medium-term impacts related to the usage of electric vehicles in collaborative networks. Results show that the optimal selection of vehicle types depends considerably on the time horizon evaluation and demand variation.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness (TRA2013-48180-C3-P and TRA2015-71883-REDT) and the Ibero-American Program for Science and Technology for Development (CYTED2014-515RT0489). Likewise, we want to acknowledge the support received by the Special Patrimonial Fund from Universidad de La Sabana (Colombia) and the doctoral grant from the UOC-Open University of Catalonia (Spain)

The location routing problem with facility sizing decisions

The location routing problem (LRP) integrates operational decisions on vehicle routing operations with strategic decisions on the location of the facilities or depots from which the distribution will take place. In other words, it combines the well-known vehicle routing problem (VRP) with the facility location problem (FLP). Hence, the LRP is an NP-hard combinatorial optimization problem, which justifies the use of metaheuristic approaches whenever large-scale instances need to be solved. In this paper, we explore a realistic version of the LRP in which facilities of different capacities are considered, i.e., the manager has to consider not only the location but also the size of the facilities to open. In order to tackle this optimization problem, three mixed-integer linear formulations are proposed and compared. As expected, they have been proved to be cost- and time- inefficient. Hence, a biased-randomized iterated local search algorithm is proposed. Classical instances for the LRP with homogeneous facilities are naturally extended to test the performance of our approach.Peer ReviewedPostprint (published version

Combining heuristics with simulation and fuzzy logic to solve a flexible-size location routing problem under uncertainty

The location routing problem integrates both a facility location and a vehicle routing problem. Each of these problems are NP-hard in nature, which justifies the use of heuristic-based algorithms when dealing with large-scale instances that need to be solved in reasonable computing times. This paper discusses a realistic variant of the problem that considers facilities of different sizes and two types of uncertainty conditions. In particular, we assume that some customers’ demands are stochastic, while others follow a fuzzy pattern. An iterated local search metaheuristic is integrated with simulation and fuzzy logic to solve the aforementioned problem, and a series of computational experiments are run to illustrate the potential of the proposed algorithm.This work has been partially supported by the Spanish Ministry of Science (PID2019-111100RB-C21/AEI/10.13039/501100011033). In addition, it has received the support of the Doctoral School at the Universitat Oberta de Catalunya (Spain) and the Universidad de La Sabana (INGPhD-12-2020).Peer ReviewedPostprint (published version

Aportaciones al conocimiento de la evolución paleoclimática y paleoambiental en la Península Ibérica durante los dos ultimos millones de años a partir del estudio de trasvertinos y espeleotemas

En este trabajo se contemplan los resultados principales del Proyecto" Reconstrucción Paleoclimática desde el Pleistoceno Medio a partir de análisis geocronológicos e isotópicos de travertinos españoles" (P. CEC FI2W-CT91-0075 " Paleoclimatological revision of climate evolution in the Western Mediterranean Region, Evaluation of altered scenarios) . Se seleccionaron cuatro áreas de depósitos travertínicos de carácter fluvial (Priego, Río Blanco), lacustre (Río Blanco, Banyoles) y aluvial (Tolox) así como una zona con depósitos espeleotémicos (Karst de la Cueva del Reguerillo). En ellas se obtuvieron datos sobre la evolución del paisaje y del clima, los travertinos y espeleotemas son indicadores de clima cálido s.l. que de forma abreviada son: O Mediante la geomorfología y dataciones (paleomagnetismo, U/Th, Resonancia de espín Resumen electrónico y racemización de aminoácidos), se determinó las historia fluvial de los travertinos de Priego y Río Blanco así como del Karst de la Cueva del Reguerillo donde, además, se dataron un paleosismo y fenómenos de neotectónica. La data más antigua obtenida mediante Resonancia de espín electrónico fue 950ka, mientras que mediante racemización de aminoácidos se dataron depósitos de más de 750ka. Mediante dataciones, sedimentología, análisis de isótopos estables y palinología se determinaron aspectos de la evolución climática de algunas áreas de la Península Ibérica. La correlación entre palinología e isotopía permitió la validación de algunos de los resultados. También se obtuvieron datos cualitativos sobre input hidraúlicos a los sistemas fluviales o kársticos

Increased expression of A Proliferation-inducing Ligand (APRIL) in lung leukocytes and alveolar epithelial cells in COPD patients with non small cell lung cancer: a possible link between COPD and lung cancer?

Background: Chronic Obstructive Pulmonary Disease (COPD) is characterized by an excessive activation of the adaptive immune system and, in particular, uncontrolled expansion of the B-cell pool. One of the key promoters of B cell expansion is A PRoliferation-Inducing Ligand (APRIL). APRIL has been strongly linked to non small cell lung cancer (NSCLC) onset and progression previously. However, little is known about the expression of APRIL in the lungs of COPD patients. Methods: Using immuno-fluorescence staining, the expression of APRIL was assessed in sections of lungs from 4 subjects with primary diagnosis of COPD (FEV1 33 ± 20 % predicted), 4 subjects with primary diagnosis of NSCLC, 4 subjects diagnosed with both COPD and NSCLC, smokers without COPD or NSCLC and 3 healthy never-smokers. The percentage of B cells, alveolar macrophages (AMs) and polymorphonuclear neutrophils (PMNs) in the lung and alveolar epithelial cells (AECs) that stained positively for APRIL was quantified using epi-fluorescence microscopy and image analysis software. Results: The percentage of APRIL-expressing B cells, AMs, PMNs and alveolar epithelial cells (AECs) was higher in patients having both COPD and NSCLC than in patients with either COPD or NSCLC alone, SC or NSC (p < 0.03 for all comparisons). The percentage of APRIL-expressing AMs and AECs (but not in B cells) was higher in patients with NSCLC alone than in patients with COPD alone. The percentage of APRIL-expressing AECs (but not B cells or AMs) was higher in COPD patients than in SC and NSC (p < 0.05 for all comparisons). The percentage of APRIL-expressing B cells, AMs and AECs cells was similar in NSC and SC. Conclusion: The percentage of APRIL-expressing B cells, AMs and AECs is higher in the lungs of patients with both COPD and NSCLC than in patients with COPD or NSCLC alone or control subjects. These findings suggest that APRIL may contribute to the pathogenesis of both COPD and NSCLC, and possibly to the development of NSCLC in patients with established COPD