A new formulation and branch-and-cut method for single-allocation hub location problems

A new compact formulation for uncapacitated single-allocation hub location problems with fewer variables than the previous Integer Linear Programming formulations in the literature is introduced. Our formulation works even with costs not based on distances and not satisfying triangle inequality. Moreover, costs can be given in aggregated or disaggregated way. Different families of valid inequalities that strengthen the formulation are developed and a branch-and-cut algorithm based on a relaxed version of the formulation is designed, whose restrictions are inserted in a cut generation procedure together with two sets of valid inequalities. The performance of the proposed methodology is tested on well-known hub location data sets and compared to the most recent and efficient exact algorithms for single-allocation hub location problems. Extensive computational results prove the efficiency of our methodology, that solves large-scale instances in very competitive times

Using the ℓ1-norm for Image-based tomographic reconstruction

This paper introduces an ℓ1-norm model based on Total Variation Minimization for tomographic reconstruction. The reconstructions produced by the proposed model are more accurate than those obtained with classical reconstruction models based on the ℓ2-norm. This model can be linearized and solved by linear programming techniques. Furthermore, the complementary slackness conditions can be exploited to reduce the dimension of the resulting formulation by removing unnecessary variables and constraints. Since the efficacy of the reduced formulation strongly depends on the quality of the dual-multipliers used when applying the reduction method, Lagrangian relaxation is used to obtain near-optimal multipliers. This allows solving larger instances in an efficient way

Quantitative Evaluation of Supported Catalysts Key Properties from Electron Tomography Studies: Assessing Accuracy Using Material-Realistic 3D-Models

Electron Tomography (ET) reconstructions can be analysed, via segmentation techniques, to obtain quantitative, 3D-information about individual nanoparticles in supported catalysts. This includes values of parameters out of reach for any other technique, like their volume and surface, which are required to determine the dispersion of the supported particle system or the specific surface area of the support; two figures that play a major role in the performance of this type of catalysts. However, both the experimental conditions during the acquisition of the tilt series and the limited fidelity of the reconstruction and segmentation algorithms, restrict the quality of the ET results and introduce an undefined amount of error both in the qualitative features of the reconstructions and in all the quantitative parameters measured from them. Here, a method based on the use of well-defined 3D geometrical models (phantoms), with morphological features closely resembling those observed in experimental images of an Au/CeO2 catalyst, has been devised to provide a precise estimation of the accuracy of the reconstructions. Using this approach, the influence of noise and the number of projections on the errors of reconstructions obtained using a Total Variation Minimization in 3D (TVM-3D) algorithm have been determined. Likewise, the benefits of using smart denoising techniques based on Undecimated Wavelet Transforms (UWT) have been also evaluated. The results clearly reveal a large impact of usual noise levels on both the quality of the reconstructions and nanometrological measurement errors. Quantitative clues about the key role of UWT to largely compensate them are also provided.This work has received support from Projects: PID2020-113006-RB-I00, PID2019-110018GA-I00, PID2020-114594GB-C22, funded by MCIN/AEI/https://doi.org/10.13039/501100011033.This work has also been co-financed by Project ref: MAT2017-87579-R and by the 2014 -2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia, Project references: FEDER-UCA18-107139, FEDERUCA18-106895 and P18-FR-1422. STEM ET experiments were recorded at the DME-UCA Node of the Spanish Singular Infrastructure for Electron Microscopy of Materials (ICTS ELECMI)

Innovación del Diseño para el Desarrollo Social

Una labor de síntesis alrededor de la gran temática de este libro que surge a partir de una serie de reflexiones y propuestas encaminadas desde la innovación del diseño para el desarrollo social, refleja una invitación al lector para enunciar a partir de su lectura nuevas discusiones sobre el quehacer del diseño con una perspectiva de innovación para este tipo de desarrollo, es pues este texto una invitación a enunciar nuevos retos y diálogos partiendo de reconocer al desarrollo social como uno de los pilares fundamentales desde la Organización de las Naciones Unidas (ONU) como parte fundamental para garantizar el mejoramiento de la vida de las personas. Desde la disciplina del diseño y retomado como eje para su discusión se pretendería establecer una serie de reflexiones y acciones que permitan atender situaciones para grupos minoritarios y vulnerables, así como apoyar esfuerzos encaminados a mejorar la calidad de vida de los integrantes de grupos y sociedades establecidas y recuperar el patrimonio cultural como parte fundamental de las identidades culturales y por tanto de la historia de la humanidad.A lo largo de la historia, el diseño, en cualquiera de sus manifestaciones, ha estado presente en todos los ámbitos. Se ha convertido en una disciplina que evoluciona al ritmo de las sociedades, que se pone al servicio de las necesidades de mercado pero también de las que requieren un abordaje distinto, observadas desde una mirada que concierne a lo social, entendido éste como lo que se reproduce o se instaura en el colectivo, en el grupo, en las comunidades, en las sociedades como parte significativa de sus cotidianeidades. El Diseño desde esta perspectiva acompaña al ser humano produciendo una significación de los objetos como parte fundamental de sus vidas, que transforma una realidad deseada en una realidad concreta, de aquí la importancia de crear una conciencia social para la praxis laboral de esta disciplina. En este sentido el campo profesional, académico y de investigación del diseño debe ocuparse de crear, difundir y divulgar el quehacer de la misma, manifestando un equilibrio entre conciencia, racionalidad y la realidad. Desde el contexto planteado, la Universidad Autónoma del Estado de México, a través de su Facultad de Arquitectura y Diseño presenta en esta obra una serie de reflexiones en torno al papel que desempeña el diseño humanístico, científico y tecnológico desde un enfoque de vanguardia e innovación para el desarrollo social, como resultado de la experiencia vertida en el Coloquio Internacional de Diseño que organiza éste año este espacio académico, en donde cada una de las aportaciones refleja la experiencia de cada uno de sus participantes; con base en ello, el presente libro integrado por una compilación de trabajos ofrece descripciones, análisis y propuestas que contribuyen a la solución de problemas procurando un desarrollo social

¿Qué queda de mí?

Este libro es una reclamación a quienes hemos sido, somos o seremos docentes. A quienes no hemos respetado a las personas que se han puesto junto a nosotros y nosotras, confiando su bien más preciado: la libertad. Estas páginas denuncian cada vez que convertimos una visión en la visión, una emoción en la emoción, un saber en el saber, un comportamiento en el comportamiento. Es un grito contra la imposición, la normalización, la neutralización y la universalización de una perspectiva particular. Una pugna contra cada proceso que no se ha conectado con las vidas de los aprendices. Un texto colaborativo realizado por alumnado de Educación y Cambio Social en el Grado en Educación Infantil de la Universidad de Málaga y coordinado por Ignacio Calderón Almendros

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 17

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 17 de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada, de acceso abierto a todas las áreas del conocimiento, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico. Con esta colección, se aspira contribuir con el cultivo, la comprensión, la recopilación y la apropiación social del conocimiento en cuanto a patrimonio intangible de la humanidad, con el propósito de hacer aportes con la transformación de las relaciones socioculturales que sustentan la construcción social de los saberes y su reconocimiento como bien público

Synthesis of mesoporous ceria using metal- and halogen-free ordered mesoporous carbon as a hard template

Authors thank the University of St Andrews for the PhD scholarship of FS. We acknowledge funding from MINECO/FEDER (Projects MAT2017-87579-R and MAT2016-81118-P) and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 823717 –ESTEEM3.Ordered mesoporous cerias were synthesised by employing metal- and halogen- free ordered mesoporous carbons (OMCs) as the hard templates in a ‘nanocasting’ procedure. TEM, small angle (SA) and wide angle (WA) XRD, and N2 physisorption analyses were used to characterise the templates, intermediates and ceria products and electron tomography (STEM-HAADF) was used to explore the 3D morphology of the ceria nanostructures grown within the carbon templates. This allowed the relationships between the structures of the OMC templates and the products to be considered in detail as two parameters were varied. These were: the method of impregnation of the ceria precursor; and the temperature of calcination of the OMC template. Of the four impregnation methods tested, the solid-liquid method was found to be the most successful. This gave a high quality product with the highest yield of uniform mesopores, and crystalline nanorods of ceria arrayed in clear long-range order, as viewed by TEM and determined in SA and WAXRD. The specific surface area and pore volume exhibited by this sample were 111 m2/g and 0.39 cm3/g, respectively. 3D electron tomography reconstructions revealed the presence of a network of ordered, nanoscale, rod-like structures interlinked in a complex fashion. The effect of calcination temperature of the template on uptake of the ceria precursor during impregnation was studied by calcining OMCs at temperatures from 350 to 800 °C and using these as hard templates for the nanocasting of ceria. Of these, the carbon template calcined at 400 °C gave the highest quality product.Publisher PDFPeer reviewe

Segmentation of scanning-transmission electron microscopy images using the ordered median problem

This paper presents new models for segmentation of 2D and 3D Scanning-Transmission Electron Micro- scope images based on the ordered median function. The main advantage of using this function is its good adaptability to the different types of images to be studied due to the wide range of weight vec- tors that can be cast. Classical segmentation models stand out for their ability to provide a segmentation of the original image very quickly and with low computational burden. However, they do not usually achieve high quality segmentations with a small number of clusters in order to classify the different ele- ments which compose the structure represented in the image. The quality of the segmentation provided by our approach is analysed using different choices of the weight vector in some real instances. More- over, improvements are proposed for the formulations to reduce the computational time needed to solve these problems by taking advantage of the weight vector structure