58 research outputs found
Aplicación de un sistema de información geográfica para visualizar vías pecuarias y obtener información sobre las mismas a partir de imágenes de satélite SPOT
Sin resume
Changes in epilithic diatom assemblages in a Mediterranean high mountain lake (Laguna de La Caldera, Sierra Nevada, Spain) after a period of drought
The epilithic diatom assemblages studied in the high mountain lake “La Caldera” (Granada, Spain) from 1996 to 1998 went through two clearly different stages. The initial one, in 1996, corresponded to the reflooding of the basin after a severe drought and was composed mainly of the colonising species Fragilaria rumpens, together with a lesser presence of Nitzschia sublinearis and Hantzschia amphioxys. The predominant presence of F. rumpens at the end of the summer of 2006 coincided with low species diversity (values of Shannon and Wiener Index: 0.3-0.6). During the following two years another assemblage established itself, dominated by Achnanthidium minutissimum, which is considered to be more stable and widespread among the lakes of the Sierra Nevada. The most notable subdominant species (less than 20% of relative abundance) in this assemblage were: Encyonema minutum, Encyonopsis microcephala and Navicula cryptocephala. The diversity values during this second period were much higher than in the first: 1.0-2.2. Nutrient concentrations were measured separately in the limnetic (epilimnetic) and benthic (epilithic) environments. These abiotic parameters show that the dynamics of ammonia and silica were much the same in both, showing a gradual decrease from the beginning to the end of the study period. Epilimnetic phosphorus followed a similar pattern to ammonia and silica. In the epilithon, nitrates and phosphates increased during the first year, only to descend notably during the second. The effect of other environmental parameters such as temperature and the preceding drought on the dynamics of the diatom assemblage are discussed. Ratio DIN:SRP let us test the different degrees of phosphorus limitation in epilithon and epilimnion environments; our results suggest that phosphorus limitation of primary production in high mountain lakes is much more severe in the limnetic environment that it is in the epilithon.Chemical analyses were funded by the European
project Mountain Lake Research (MOLAR)
Implementation and Provisioning of Federated Networks in Hybrid Clouds (pre-print)
Federated cloud networking is needed to allow the seamless and efficient interconnection of resources distributed among different clouds. This work introduces a new cloud network federation framework for the automatic provision of Layer 2 (L2) and layer 3 (L3) virtual networks to interconnect geographically distributed cloud infrastructures in a hybrid cloud scenario. After a revision of existing encapsulation technologies to implement L2 and L3 overlay networks, the paper analyzes the main topologies that can be used to construct federated network overlays within hybrid clouds. In order to demonstrate the proposed solution and compare the different topologies, the article shows a proof-of-concept of a real federated network deployment in a hybrid cloud, which spans a local private cloud, managed with OpenNebula, and two public clouds, two different regions of mazon EC2. Results show that L2 and L3 overlay connectivity can be achieved with a minimal bandwidth overhead, lower than 10%
Interoperable Federated Cloud Networking
The BEACON framework enables the provision of federated cloud infrastructures, with special emphasis on inter-cloud networking and security issues, to support the automated deployment of applications and services across different clouds and datacenters. BEACON is distributed as open source (see http://github.com/BeaconFramework) and some enhancements are being contributed to the OpenNebula and OpenStack cloud management platforms
Cross-Site Virtual Network in Cloud and Fog Computing
The interconnection of the different geographically dispersed cloud and fog infrastructures is a key issue for the development of the fog technology. Although most existing cloud providers and platforms offer some kind of connectivity services to allow the interconnection with external networks, these services exhibit many limitations and they are not suitable for fog computing environments. In this work we present a hybrid fog and cloud interconnection framework, which allows the automatic provision of cross-site virtual networks to interconnect geographically distributed cloud and fog infrastructures. This framework provides a scalable and multi-tenant solution, and a simple and generic interface for instantiating, configuring and deploying Layer 2 and Layer 3 overlay networks across heterogeneous fog and cloud platforms, with abstraction from the underlying cloud/fog technologies and network virtualization technologies
Methodology for drafting least environmental cost railway corridors. Practical case study: High speed rail route Huelva (Spain) - Faro(Portugal)
El trabajo contempla el desarrollo de una
metodología de Evaluación Multicriterio
para establecer el corredor ferroviario de
mínimo impacto ambiental entre Huelva
(España) y Faro (Portugal). Este estudio
forma parte del proyecto Interreg “Evaluación
ambiental estratégica (EAE) de las
posibles conexiones ferroviarias (Convencional
/ Alta Velocidad) Huelva – Algarbe
(EAE-FER)” (www.web-rise.eu). La metodología
prevé en primer lugar la selección
de los factores ambientales que van
a intervenir en el modelo y la recogida
y homogeneización de la información
ambiental existente entre los dos países,
así como su posterior implementación en
un Sistema de Información Geográfica. A
continuación se calculan las superficies
de fricción (resistencia al desplazamiento)
de los factores seleccionados, y mediante
combinación lineal ponderada e introduciendo
como restricciones los limitantes
se obtiene la superficie final de fricción,
a partir de la cual, y junto con los puntos
origen y destino es posible obtener el
corredor y camino mínimos.This work enables the developing of a
multi-criteria assessment methodology to
find the least environmental cost railway
corridor that connects Huelva (Spain) and
Faro (Portugal). This paper is part of Interreg
Project entitled “Strategical impact
assessment (SIA) for the possible railway
connections (high speed/conventional)
Huelva-Algarve (EAE-FER)” (www.webrise.
eu). The approach enables, in the
first place, the selection of the environmental
factors that will be considered in
the model, the homogenization of environmental
information from the two different
countries, as well as its subsequent
implementation in a GIS (Geographical
Information System). In the second place
cost surfaces are calculated from selected
factors, and using a linear weighted combination
and introducing the limited factors
as a restriction, the final friction surface is
obtained, which in conjunction with the
points of origin and destination, it is possible
to obtain the least- environmental-cost
corridor and alignment
A unilateral robotic knee exoskeleton to assess the role of natural gait assistance in hemiparetic patients.
Background: Hemiparetic gait is characterized by strong asymmetries that can severely affect the quality of life of
stroke survivors. This type of asymmetry is due to motor deficits in the paretic leg and the resulting compensations in
the nonparetic limb. In this study, we aimed to evaluate the effect of actively promoting gait symmetry in hemiparetic
patients by assessing the behavior of both paretic and nonparetic lower limbs. This paper introduces the design and
validation of the REFLEX prototype, a unilateral active knee–ankle–foot orthosis designed and developed to naturally
assist the paretic limbs of hemiparetic patients during gait.
Methods: REFLEX uses an adaptive frequency oscillator to estimate the continuous gait phase of the nonparetic
limb. Based on this estimation, the device synchronically assists the paretic leg following two different control
strategies: (1) replicating the movement of the nonparetic leg or (2) inducing a healthy gait pattern for the paretic
leg. Technical validation of the system was implemented on three healthy subjects, while the effect of the generated
assistance was assessed in three stroke patients. The effects of this assistance were evaluated in terms of interlimb
symmetry with respect to spatiotemporal gait parameters such as step length or time, as well as the similarity
between the joint’s motion in both legs.
Results: Preliminary results proved the feasibility of the REFLEX prototype to assist gait by reinforcing symmetry. They
also pointed out that the assistance of the paretic leg resulted in a decrease in the compensatory strategies developed
by the nonparetic limb to achieve a functional gait. Notably, better results were attained when the assistance
was provided according to a standard healthy pattern, which initially might suppose a lower symmetry but enabled a
healthier evolution of the motion of the nonparetic limb.
Conclusions: This work presents the preliminary validation of the REFLEX prototype, a unilateral knee exoskeleton for
gait assistance in hemiparetic patients. The experimental results indicate that assisting the paretic leg of a hemiparetic
patient based on the movement of their nonparetic leg is a valuable strategy for reducing the compensatory mechanisms
developed by the nonparetic limb.post-print6406 K
Disk Image Storage, Distribution and Caching for Edge Cloud Infrastructures
Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaFALSEMinisterio de Ciencia e Innovación (MICINN)Comunidad de Madridunpu
Latency and resource consumption analysis for serverless edge analytics
The serverless computing model, implemented by Function as a Service (FaaS) platforms, can offer several advantages for the deployment of data analytics solutions in IoT environments, such as agile and on-demand resource provisioning, automatic scaling, high elasticity, infrastructure management abstraction, and a fine-grained cost model. Nonetheless, in case of applications with strict latency requirements, the cold start problem in FaaS platforms can represent an important drawback. The most common techniques to alleviate this problem, mainly based on instance pre-warming and instance reusing mechanisms, are usually not well adapted to different application profiles and, in general, can entail an extra expense of resources. In this work, we analyze the effect of instance pre-warming and instance reusing on both, application latency (response time) and resource consumption, for a typical data analytics use case (a machine learning application for image classification) with different input data patterns. Furthermore, we propose to extend the classical centralized cloud-based serverless FaaS platform to a two-tier distributed edge-cloud platform to bring the platform closer to the data source and reduce network latencies
On Demand/Agile Deployment of Edge Cloud Infrastructures for Federated Learning
Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaFALSEMinisterio de Ciencia e Innovación (MICINN)Comunidad de Madridunpu
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