421 research outputs found

    Performance Evaluation of Distributed Mobility Management Protocols: Limitations and Solutions for Future Mobile Networks

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    Mobile Internet data traffic has experienced an exponential growth over the last few years due to the rise of demanding multimedia content and the increasing number of mobile devices. Seamless mobility support at the IP level is envisioned as a key architectural requirement in order to deal with the ever-increasing demand for data and to efficiently utilize a plethora of different wireless access networks. Current efforts from both industry and academia aim to evolve the mobility management protocols towards a more distributed operation to tackle shortcomings of fully centralized approaches. However, distributed solutions face several challenges that can result in lower performance which might affect real-time and multimedia applications. In this paper, we conduct an analytical and simulated evaluation of the main centralized and proposed Distributed Mobility Management (DMM) solutions. Our results show that, in some scenarios, when users move at high speed and/or when the mobile node is running long-lasting applications, the DMM approaches incur high signaling cost and long handover latency.This work was supported by the Government of Extremadura under Grant no. GR15099 and by the European Regional Development Fund Programme (2014–2020) and the Regional Fund, through Computing and Advanced Technologies Foundation of Extremadura (COMPUTAEX)

    Mechanistic studies on the: N -alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands

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    Iridium(i) cyclooctadiene complexes featuring O- and N-donor functionalised NHC ligands efficiently catalyse the C-N coupling of amines with alcohols through a borrowing hydrogen mechanism. These catalysts have been applied for the N-alkylation of several aromatic and aliphatic primary amines with a range of alcohols including benzyl alcohol derivatives, straight-chain primary alcohols and secondary alcohols. The cationic complex [Ir(NCCH3)(cod){MeIm(2-methoxybenzyl)}]+ (cod = 1, 5-cyclooctadiene, MeIm = 3-methylimidazol-2-ylidene) having a rigid O-donor wingtip exhibits the best catalytic performance for the N-alkylation of aniline with benzyl alcohol giving a quantitative conversion to N-benzylaniline in 3 h. Experimental and theoretical studies at the DFT level on the N-alkylation of aniline with benzyl alcohol catalysed by the model compound [IrCl(cod)(IMe)] (IMe = 1, 3-dimethyl-imidazol-2-ylidene) support the participation of the iridium catalyst not only in the alcohol dehydrogenation and imine hydrogenation steps but also in the key step leading to the formation of the new C-N bond. Nucleophilic attack of an iridium-amido species generated in basic medium on the electrophilic aldehyde results in a hemiaminolate intermediate species from which the hemiaminal is released by alcoholysis. The free hemiaminal dehydrates to give the corresponding intermediate imine product that is hydrogenated by the iridium catalyst to the N-alkylated amine product. The iridium(i) complexes featuring functionalised NHC ligands are more active than [IrCl(cod)(IMe)] which highlights the positive influence of the functional group on the N-alkylation catalytic activity

    The feeding of American plaice (Hippoglossoides platessoides), Redfish (Sebastes marinus) and Cod (Gadus morhua) in the Flemish Cap during July 1988

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    A randomly stratified bottom-trawl survey was realized in the Flemish Cap (NAFO Div. 3M) in July 1988. The stomach contents of three species were studied: 320 of American plaice (Hippoglossoides platessoides), 203 of redfish (Sebastes Marinus) and 468 of cod (Gadus morhua). The cod specimens were classified taking into account age groups; in the case of other species by length classes. The food items, the prey occurrence index and the diversity index were determined too. The Schoener overlap index was calculated to study the intraspecific diet overlap in cod and the interspecific diet overlap between the three species. The relation between predator size (cod) and prey size (redfish) was also studied

    Diseño y desarrollo de una aplicación de escritorio como soporte para la toma de decisiones de zonas de control en la asignación de las ayudas agrarias

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    El control de las ayudas agrarias es imprescindible dentro del contexto normativo de la agricultura europea. Los procesos de control que realizan las administraciones públicas se basan, en gran medida, en visitas de campo a zonas concretas que varían anualmente en función de factores definidos para cada campaña. Esta metodología origina una movilización importante de personal y equipos que redunda en altos costes económicos y temporales, lo que implica que las zonas elegidas para el control sean las más óptimas posibles para rentabilizar al máximo el trabajo. Esta necesidad de optimización pone de manifiesto la necesidad de automatizar la selección de las zonas, tal que los criterios que intervengan en el proceso sean valorados de forma objetiva e imparcial atendiendo a parámetros que aparecen regulados en la normativa vigente. Este marco planteado es idóneo para el desarrollo y empleo de un SIG que permita de manera automática, sistemática y objetiva la selección de dichas zonas mediante una evaluación multicriterio. El objetivo de este trabajo es el desarrollo de una aplicación de escritorio adaptada a unas necesidades particulares, empleando librerías de código libre para determinar las zonas de control mediante una evaluación multicriterio.The control of agricultural aid is essential in the context of European agricultural policy. The control processes carried out by the government are based on field visits to specific areas, such areas change annually depending on factors for each campaign. This methodology results in a significant mobilization of personnel and equipement causing high economic costs and time, which means that the areas chosen for the control must be the most optimal possible to maximize the job. The need for optimization emphasizes the need to automate the selection of areas, such that the criteria involved in the process must be evaluated objectively and impartially on the basis of parameters present in the regulations. The framework proposed is suitable for the development and use of a GIS to automatically enable, the systematic and objective selection of these areas through a multi-criteria evaluation. The aim of this study is to develop a desktop application adapted to some particular needs, using open source libraries to identify areas of control via a multicriteria evaluation

    Estudio descriptivo de las cavidades pleurales residuales complicadas tratadas en un Servicio de Cirugía Torácica

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    Introducción: Las cavidades pleurales residuales se definen como espacios pleurales causados por una falta de reexpansión pulmonar principalmente secundario a infecciones pleurales o cirugías torácicas. Estas pueden cronificarse y complicarse si no logran resolverse con los tratamientos de primera línea (drenaje torácico, fibrinolíticos o decorticación quirúrgica). Material y Métodos: Estudio descriptivo retrospectivo de los pacientes con cavidades pleurales residuales complicadas (CPRC) en el Servicio de Cirugía Torácica del Complejo Hospitalario Universitario de Albacete desde noviembre del 2004 hasta mayo del 2015. Resultados: Sesenta y tres pacientes fueron diagnosticados, con una mayor frecuencia en hombres (n=57; 90,5%). Del total de pacientes intervenidos en este periodo, el 16,27% de cirugías fueron secundarias a esta patología. La patología infecciosa fue la más frecuente (n=35; 55,6%) y dentro de la post-quirúrgica la neumonectomía (n=8; 42,1%), con una media de días desde la intervención quirúrgica hasta el diagnóstico de 190,7 días. En 43 pacientes (68,3%) el cultivo del líquido pleural fue positivo. En 17 pacientes (27%) se asoció a una fístula broncopleural. De los 63 pacientes, 16 (25,4%) recibieron un único tratamiento quirúrgico (25,4%), mientras que 47 (74,6%), precisaron más de un tratamiento. En 39 casos (61,9%) la cavidad pleural complicada se resolvió por medio de los tratamientos, mientras que no lo hizo en 24 (38,1%) pacientes. Conclusiones: A pesar de ser una patología poco frecuente continua presente en la actualidad, principalmente como complicación postquirúrgica o infecciosa. Los tratamientos descritos hasta la fecha no revelan una alta eficacia.Introduction: Residual pleural cavities are pleural spaces caused by a lack of pulmonary reexpansion mainly secondary to pleural infections or thoracic surgeries. If they can not be solved with first line treatments (thoracic drainage, fibrinolytics or surgical decortication), these can become cronic and complicate. Material and Methods: Retrospective descriptive study of patients with complicated residual pleural cavities at the Thoracic Surgery Service of the “Complejo Hospitalario Universitario de Albacete” from November 2004 to May 2015. Results: Sixty-three patients were diagnosed, showing that incidence was more frequent in men (n=57; 90.5%). 16.27% of the surgeries treated within this period were secondary to this pathology. The infectious pathology was the most frequent (n = 35; 55.6%), whereas within the postoperative group, it was pneumonectomy (n = 8; 42.1%), with 190.7 days in average from surgical intervention to the diagnosis. In 43 patients (68.3%), the pleural fluid culture was positive. In 17 patients (27%), it was associated with a bronchopleural fistula. From the 63 patients, 16 (25.4%) received a single surgical treatment (25.4%), while 47 (74.6%) required more than one treatment. In 39 cases (61.9%), the complicated pleural cavity was resolved, whereas in 24 (38.1%) patients it wasn’t. Conclusions: Despite it being a rare pathology, it is still present today, mainly as a post-surgical or infectious complication. To date, the treatments described haven’t exhibited high efficacy

    Control de campo de ayudas agrarias basado en telefonía móvil

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    Hoy día, la mayoría de los datos que se manejan llevan asociados una componente geográfica. Bajo este contexto asistimos a un acercamiento de tecnologías empleadas por usuarios expertos hacia usuarios genéricos. En este marco se plantea la integración de las nuevas tecnologías en el control de las ayudas agrarias. Actualmente, los procesos de control de ayudas agrarias se basan fundamentalmente en visitas de campo con objeto de certificar el uso del suelo. Esta metodología de control origina una movilización importante de personal y equipos, empleando simultáneamente dispositivos como cámara fotográfica, tablet-PC, GPS, etc. El objetivo de este proyecto ha sido el desarrollo de una aplicación para telefonía móvil aprovechando los distintos sensores que se encuentran integrados en él, utilizando terminales que añaden nuevas funcionalidades, asegurando la integridad de la información, mejorando su correcta interpretación así como estableciendo diferentes canales de difusión. El proyecto se ha desarrollado bajo Android, empleando librerías de código abierto y de ejecución independiente al fabricante del dispositivo telefónico. El resultado es un software que integra información de diferentes sensores, presentando el terminal móvil apto para los trabajos de control de campo, reduciendo el material a emplear y mejorando la integridad de la información.Today, most data we use is associated with a geographic component. In this context we are witnessing a convergence in technologies used by expert users to generic users. In this framework we look at the integration of new technologies in the control of agricultural aid. Currently, control processes agricultural subsidies are fundamentally based on field visits in order to certify the land use. This control methodology results in a significant mobilization of personnel and equipment, using devices like a camera, tablet PC, GPS, etc. The objective of this project has been to develop a mobile application taking advantage of the different sensors that are integrated into it, using terminals that add new functionality, ensuring data integrity, improving its correct interpretation as well as establishing different channels diffusion. The project has been developed under Android, using open source libraries independent to the device manufacturer. The result is software that integrates information from different sensors, introducing the mobile terminal suitable for the work of field control, reducing the material to be used and improved data integrity

    Características morfológicas y estructura superficial de montículos submarinos del talud inferior del margen continental canario (O de las Islas Canarias)

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    Extrusive edifices and structural reliefs, catalogued as mounds and located on the seafloor to the west of Canary Islands were analyzed by acoustic data obtained with multibeam and parametric echosounders during several oceanographic expeditions. They were carried out at deep waters, from 4800 to 5200 m, and they have allowed characterizing 41 newly discovered submarine structures which occur either as isolated edifices or clustered mounds. These features have circular to elongated shapes with diameters of 2-24 km and relief heights of 10 to 250 m, showing different flank slopes of 2-50°. They generally display mounded forms and show morphological elements as ridges, near-circular rock outcrops, depressions and fault scarps together with mass flow and slide deposits located at the vicinity of the edifices. Two types of extrusive features are evidenced by the morphological and seismic data analyses, the first one probably corresponds to high velocity extrusions that reach the seafloor surface and the second one is probably formed by the combination of faulted structures and low velocity extrusions that produce singular domes in the shallower sedimentary records. Based on both analyses, extrusive phenomena represent the dominant mechanism for mound field evolution in the Canary lower slope region.Versión del edito

    Diagrammatic self-energy approximations and the total particle number

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    There is increasing interest in many-body perturbation theory as a practical tool for the calculation of ground-state properties. As a consequence, unambiguous sum rules such as the conservation of particle number under the influence of the Coulomb interaction have acquired an importance that did not exist for calculations of excited-state properties. In this paper we obtain a rigorous, simple relation whose fulfilment guarantees particle-number conservation in a given diagrammatic self-energy approximation. Hedin's G(0)W(0) approximation does not satisfy this relation and hence violates the particle-number sum rule. Very precise calculations for the homogeneous electron gas and a model inhomogeneous electron system allow the extent of the nonconservation to be estimated

    Hydrogen embrittlement risk of high strength galvanized steel in contact with alkaline media

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    The critical conditions for hydrogenembrittlement (HE) risk of highstrengthgalvanizedsteel (HSGS) wires and tendons exposed to alkaline concrete pore solutions have been evaluated by means of electrochemical and mechanical testing. There is a relationship between the hydrogenembrittlementrisk in HSGS and the length of hydrogen evolution process in alkalinemedia. The galvanizedsteel suffers anodic dissolution simultaneously to the hydrogen evolution which does not stop until the passivation process is completed. HSGS wires exposed to a very highalkalinemedia have showed HE risk with loss in mechanical properties only if long periods with hydrogen evolution process take place with a simultaneous intensive galvanized coating reduction
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