851 research outputs found
The homotopy fixed point set of Lie group actions on elliptic spaces
Let be a compact connected Lie group, or more generally a path connected
topological group of the homotopy type of a finite CW-complex, and let be a
rational nilpotent -space. In this paper we analyze the homotopy type of the
homotopy fixed point set , and the natural injection . We show that if is elliptic, that is, it has
finite dimensional rational homotopy and cohomology, then each path component
of is also elliptic. We also give an explicit algebraic model of the
inclusion based on which we can prove, for instance, that for a torus,
is injective in rational homotopy but, often, far from being a
rational homotopy equivalence.Comment: 32 page
Estudio del sistema de diálisis para la desalcoholización parcial de vinos blancos
El cambio climático es algo palpable y en gran medida influencia, igual que a otros cultivos muy necesarios, al cultivo de la vid. Uno de sus efectos es el desequilibrio de la maduración de las plantas haciendo que el contenido en azúcar de la uva aumente y consecuentemente, lo haga el grado alcohólico del producto final. Este trabajo se basa en el estudio de varias membranas seleccionadas por el Grupo de Superficies y Materiales Porosos de la Uva (SMAP) para reducir el alcohol del vino mediante diálisis y analizar el impacto de este proceso sobre el vino. Tras seleccionar 3 membranas con diferentes grados de selectividad llegamos a la conclusión que la membrana de 2500 Da, es capaz de eliminar una mayor cantidad de alcohol, consiguiendo que químicamente el vino no sufra alteraciones en su composición que pueden resultar perjudiciales para el consumidor finalGrado en Enologí
New records of biting midges of the genus Culicoides Latreille from Mexico (Diptera: Ceratopogonidae)
We provide the first records of six species of biting midges (Diptera: Ceratopogonidae) in the genus
Culicoides Latreille from Mexico: C. baueri Hoffman, C. castillae Fox, C. debilipalpis Lutz, C. iriartei Fox, C. leoni
Barbosa and C. pusilloides Wirth and Blanton. In addition, C. leopoldoi Ortiz is confirmed from Mexico, and new
records are included for 25 other species previously recorded in Mexico: C. arubae Fox and Hoffman, C. blantoni Vargas
and Wirth, C. crepuscularis Malloch, C. daedalus Macfie, C. diabolicus Hoffman, C. foxi Ortiz, C. furens (Poey), C.
gabaldoni Ortiz, C. haematopotus Malloch, C. hylas Macfie, C. insignis Lutz, C. jamaicensis Edwards, C. luteovenus
Root and Hoffman, C. neopulicaris Wirth, C. nigrigenus Wirth and Blanton, C. pampoikilus Macfie, C. panamensis
Barbosa, C. paraensis (Goeldi), C. phlebotomus (Williston), C. poikilonotus Macfie, C. pusillus Lutz, C. stigmalis Wirth,
and all three species in the C. (Monoculicoides) variipennis complex, C. variipennis (Coquillett), C. occidentalis Wirth
and Jones, and C. sonorensis Wirth and Jones
Generalized parametric solutions in Stokes flow
The final publication is available at Springer via https://doi.org/10.1016/j.cma.2017.07.016Design optimization and uncertainty quantification, among other applications of industrial interest, require fast or multiple queries of some parametric model. The Proper Generalized Decomposition (PGD) provides a separable solution, a computational vademecum explicitly dependent on the parameters, efficiently computed with a greedy algorithm combined with an alternated directions scheme and compactly stored. This strategy has been successfully employed in many problems in computational mechanics. The application to problems with saddle point structure raises some difficulties requiring further attention. This article proposes a PGD formulation of the Stokes problem. Various possibilities of the separated forms of the PGD solutions are discussed and analyzed, selecting the more viable option. The efficacy of the proposed methodology is demonstrated in numerical examples for both Stokes and Brinkman models.Peer ReviewedPostprint (author's final draft
Proper generalized decomposition for parameterized Helmholtz problems in heterogeneous and unbounded domains: application to harbor agitation
Solving the Helmholtz equation for a large number of input data in an heterogeneous media and unbounded domain still represents a challenge. This is due to the particular nature of the Helmholtz operator and the sensibility of the solution to small variations of the data. Here a reduced order model is used to determine the scattered solution everywhere in the domain for any incoming wave direction and frequency. Moreover, this is applied to a real engineering problem: water agitation inside real harbors for low to mid-high frequencies. The Proper Generalized Decomposition (PGD) model reduction approach is used to obtain a separable representation of the solution at any point and for any incoming wave direction and frequency. Here, its applicability to such a problem is discussed and demonstrated. More precisely, the contributions of the paper include the PGD implementation into a Perfectly Matched Layer framework to model the unbounded domain, and the separability of the operator which is addressed here using an efficient higher-order projection scheme. Then, the performance of the PGD in this framework is discussed and improved using the higher-order projection and a Petrov-Galerkin approach to construct the separated basis. Moreover, the efficiency of the higherorder projection scheme is demonstrated and compared with the higher-order singular value decomposition
Approach to Facilitating Geospatial Data and Metadata Publication Using a Standard Geoservice
Nowadays, the existence of metadata is one of the most important aspects of effective discovery of geospatial data published in Spatial Data Infrastructures (SDIs). However, due to lack of efficient mechanisms integrated in the data workflow, to assist users in metadata generation, a lot of low quality and outdated metadata are stored in the catalogues. This paper presents a mechanism for generating and publishing metadata through a publication service. This mechanism is provided as a web service implemented with a standard interface called a web processing service, which improves interoperability between other SDI components. This work extends previous research, in which a publication service has been designed in the framework of the European Directive Infrastructure for Spatial Information in Europe (INSPIRE) as a solution to assist users in automatically publishing geospatial data and metadata in order to improve, among other aspects, SDI maintenance and usability. Also, this work adds more extra features in order to support more geospatial formats, such as sensor data.Sergio Trilles has been funded by the postdoctoral programme Vali+d (GVA) (grant number
APOSTD/2016/058). This work has been funded by the European Commission through the GEO-C project
(H2020-MSCA-ITN-2014, Grant Agreement number 642332, http://www.geo-c.eu/)
Monitorización de datos de calidad de aire
Cada vez más somos testigos del despliegue de redes de
sensores que miden el estado del entorno en el que vivimos.
Estas redes aportan grandes volúmenes de información en
formatos y escalas muy diversas. Encontramos ejemplos de
datos de diversa naturaleza, desde condiciones climáticas, hasta
concentraciones de elementos contaminantes debido a la
actividad humana como el transporte, y la industria.
En este trabajo describimos como la publicación de estos datos
mediante servicios que proporcionen un acceso estructurado y
basado en estándares permite una mejor integración de estos
datos, tanto para su visualización desde diversas plataformas
(web o móvil) como para su consumo mediante procesos de
análisis que permitan extraer valor añadido y asistir en la toma
de decisiones. Uno de los principales objetivos es incrementar la
interoperabilidad de acceso a estos datos y que un usuario a
través de diferentes dispositivos pueda conocer en tiempo real
las condiciones de una ubicación concreta.We are progressively witnessing how more and more sensor networks measure
the environment where we live. These networks provide big data volumes in
different formats and scales. We find examples of very diverse data, be it from
climatic conditions to the levels of concentration of polluting elements following
the human activity, such as those related to transport and industries. This article
describes how the publication of this data through services providing a
structured and standard-based access allows a better integration of the said
data, both for its visualisation from different platforms (web, or mobile devices)
and its consumption through analysis processes allowing to extract added value
and assist in the decision making process. One of its main aims is to increase
the interoperability of access to this data so that any user may know in real time
and through different devices the conditions of a given location
The role of endoscopic ultrasound in the evaluation of rectal cancer
Accurate staging of rectal cancer is essential for selecting patients who can undergo sphincter-preserving surgery. It may also identify patients who could benefit from neoadjuvant therapy. Clinical staging is usually accomplished using a combination of physical examination, CT scanning, MRI and endoscopic ultrasound (EUS). Transrectal EUS is increasingly being used for locoregional staging of rectal cancer. The accuracy of EUS for the T staging of rectal carcinoma ranges from 80-95% compared with CT (65-75%) and MR imaging (75-85%). In comparison to CT, EUS can potentially upstage patients, making them eligible for neoadjuvant treatment. The accuracy to determine metastatic nodal involvement by EUS is approximately 70-75% compared with CT (55-65%) and MR imaging (60-70%). EUS guided FNA may be beneficial in patients who appear to have early T stage disease and suspicious peri-iliac lymphadenopathy to exclude metastatic disease
Solution of geometrically parametrised problems within a CAD environment via model order reduction
The main objective of this work is to describe a general and original approach for computing an off-line solution for a set of parameters describing the geometry of the domain. That is, a solution able to include information for different geometrical parameter values and also allowing to compute readily the sensitivities. Instead of problem dependent approaches, a general framework is presented for standard engineering environments where the geometry is defined by means of NURBS. The parameters controlling the geometry are now the control points characterising the NURBS curves or surfaces. The approach proposed here, valid for 2D and 3D scenarios, allows a seamless integration with CAD preprocessors. The proper generalised decomposition (PGD), which is applied here to compute explicit geometrically parametrised solutions, circumvents the curse of dimensionality. Moreover, optimal convergence rates are shown for PGD approximations of incompressible flows
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