Browsing by Author "Pérez, Susana"
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Item Adaptive Weighted Round Robin (AWRR) scheduling for optimization of the wireless medium virtualisation(2010) Hernando, Gorka; Pérez, Susana; Cabero, José María; GENERAL; Tecnalia Research & InnovationNetwork virtualisation has been recently presented as a mean to overcome the saturation of the current Internet by sharing the same infrastructure by different network operators. This work considers virtualisation of the wireless medium, a way to share common network physical resources by different Virtual Operators based on a Time Division Multiple Access technique. We propose an Adaptive Weighted Round Robin scheduler as a means to optimize the assignment of time slots to each virtual operator and improve the performance of the system. End-to-end delay and packet loss are the metrics used in this paper to show the potential and limitations of wireless virtualisation as a way to increase the network usage. This research is presented as a simulation-based study developed over the widely used NS2 network simulator. Different scenarios and network topologies are considered in order to assess the benefits of using the proposed scheduler.Item Enhanced CO2 Methanation by New Microstructured Reactor Concept and Design(2019-06-15) Pérez, Susana; Aragón, Jorge J.; Peciña, Iñigo; Garcia-Suarez, Eduardo J.; VALORIZACIÓN DE RESIDUOS; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationA novel multichannel minireactor with channel internal diameter in the range of millimeters has been conceptually designed and constructed. Its configuration confers to the new concept reactor some features and advantages compared to conventional fixed-bed reactors g.e. better mass-transfer, avoid hot-spots formation, increased performance (10–20%). Consequently, this new reactor concept is ideal to be applied to exothermic reactions such as the Sabatier reaction that demands continuous removal of the heat produced to avoid hot-spot formation and the sintering of the catalyst. Thanks to its configuration, this reactor could control effectively the heat generated by the reaction and several tests were carried out to validate the reactor features. The results obtained demonstrate that the catalysts activity in the reaction is improved with the application of the novel reactor respect the conventional fixed- and fluidized-bed ones and neither catalyst sintering, nor pressure drop was appreciated during the catalytic tests. At the best reaction conditions, Tecnalia’s multichannel minireactor can handle 820 Nm3/h of CO2 per square meter of channel section showing the enormous potential of the new reactor concept.Item Implementation and comparison of AODV and OLSR routing protocols in an ad-hoc network over bluetooth(2009) Hernando, Gorka; Cabero, José María; Jodrá, José Luis; Pérez, Susana; Tecnalia Research & Innovation; GENERALAd-Hoc networking is one of the most impacting architectures in the development of the Future Internet, where the nodes are expected to be wireless and mobile. Unlike the traditional IP-based and simulation-based approaches inside the Ad-Hoc research field, this work presents a real implementation of proactive (OLSR) and reactive protocols (AODV) over real Bluetooth devices (non-IP approach) in static and dynamic scenarios. Along the paper we point out many handicaps that have been solved in order to make Bluetooth work as supporting technology (the need for a previously established connection to, the lack of broadcast messages, the overhead...). We have carried out a set of experiments to compare the potential and limitations of both protocols. This work was developed inside the Future Internet project supported by the Basque Government within the ETORTEK Programme and the FuSeN project supported by the Spanish Ministerio de Ciencia e Innovación.Item Mobility-Aware Distributed Embedding (MADE) of virtual networks(2010) Hernando, Gorka; Pérez, Susana; Cabero, José María; GENERAL; Tecnalia Research & InnovationNetwork virtualisation has been recently presented as a mean to overcome the saturation of the current Internet by sharing the same infrastructure by different network operators. The efficient embedding of Virtual Networks in the physical substrate represents one of the main challenges associated to this technique, since it is necessary to set up a coordinated procedure to provide the requested set of resources in the most beneficial way. We propose a novel embedding protocol, designed in a distributed manner, and especially focused on solving the problems derived from the dynamicity of the nodes in mobile environments. Our Mobility-Aware Distributed Embedding (MADE) protocol applies the well known Path Splitting and Migration techniques in order to optimize the use of the physical resources. A simulation-based study lets us show the efficiency of our protocol and the good results in terms of acceptance and finalization of Virtual Networks. 1Item A total process for the sewage sludge treatment(2005) Belsué, Mikel; Pérez, Susana; Etxebeste, Oier; Gaballah, I.; Mishra, B.; Solozabal, R.; Tanaka, M.; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOSThe present paper describes a total process for the treatment of the sludge produced in the management of urban waste waters that allows the waste energy valorization. The main phases of this process are: drying of the sludge, gasification of the dried sludge and, last, the use of the combustible gas obtained in the previous phase. By this development, the sewage sludges are revalued besides eliminating the environmental impact that these wastes will cause in the near future.