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Cloud technology is an attractive infrastructure solution that provides customers with an almost unlimited on-demand computational capacity using a pay-per-use approach, and allows data centers to increase their energy and economic savings by adopting a virtualized resource sharing model. However, resources such as graphics processing units (GPUs), have not been fully adapted to this model. Although, general-purpose computing on graphics processing units (GPGPU) is becoming more and more popular, cloud providers lack of flexibility to manage accelerators, because of the extended use of peripheral component interconnect (PCI) passthrough techniques to attach GPUs to virtual machines (VMs). For this reason, we design, develop, and evaluate a service that provides a complete management of cloudified GPUs (cGPUs) in public cloud platforms. Our solution enables an effective, anonymous, and transparent access from VMs to cGPUs that are previously scheduled and assigned by a full resource manager, taking into account new GPU selection policies and new working modes based on the locality of the physical accelerators and the exclusivity when accessing them. This easy-to-adopt tool improves the resource availability through different cGPUs configurations for end-users, whilst cloud providers are able to achieve a better utilization of their infrastructures and offer more competitive services. Scalability results in a real cloud environment demonstrate that our solution introduces a virtually null overhead in the deployment of VMs. Besides, performance experiments reveal that GPU-enabled clusters based on cloud infrastructures can benefit from our proposal not only exploiting better the accelerators, but also serving more jobs requests per unit of time.

Nowadays, video coding and transcoding have a great interest and important impact in areas such as high-definition video and entertainment, healthcare and elderly care, high-resolution video surveillance, self-driving cars, or e-learning. This growing demand for high-resolution video boosts the proposal of new codecs and the development of their encoders that require high computational requirements. Therefore, new strategies are needed to accelerate them. Cloud infrastructures offer interesting features for video coding, such as on-demand resource allocation, multitenancy, elasticity, and resiliency. This paper proposes a cloud-based distributed architecture, where the network and the storage layers have been tuned, to accelerate video encoders over an elastic number of worker encoder nodes. Moreover, an application is developed and executed in the proposed architecture to allow the creation of encoding jobs, their dynamic assignment, their execution in the worker encoder nodes, and the reprogramming of the failed ones. To validate the proposed architecture, the parallel execution of existing video encoders, x265 for H.265/HEVC and libvpx-vp9 for VP9, has been evaluated in terms of scalability, workload, and job distribution, varying the number of encoder nodes. The quality of the encoded videos has been analyzed for different bit rates and number of frames per job using the Peak Signal-to-Noise Ratio (PSNR). Results show that our proposal maintains video quality compared with the sequential encoding while improving encoding time, which can decrease near 90%, depending on the codec and the number of encoder nodes.

RESUMEN Los sistemas fotovoltaicos son fuentes emergentes de energías renovables que generan electricidad a partir de la radiación solar. El monitoreo de los sistemas fotovoltaicos aislados proporciona información necesaria que permite a sus propietarios mantener, operar y controlar estos sistemas, reduciendo los costes de operación y evitando indeseadas interrupciones en el suministro eléctrico de zonas aisladas. En este artículo, se propone el desarrollo de una plataforma para el monitoreo de sistemas fotovoltaicos aislados en el Ecuador con el objetivo fundamental de desarrollar una solución escalable, basada en el uso de software libre, en el empleo de sensores de bajo consumo y en el desarrollo de servicios web en la modalidad ‘Software as a Service’ (SaaS) para el procesamiento, gestión y publicación de información registrada y la creación de un innovador centro de control solar fotovoltaico en el Ecuador. Palabras clave: Servicios Cloud, monitoreo remoto, sistemas fotovoltaicos. ABSTRACT Photovoltaic systems are typical renewable energy sources that generate electricity from solar radiation. Monitoring isolated PV systems is necessary to provide information that allows their holders to maintain, operate and control these systems, reducing installations costs and avoiding unwanted electric power disruptions in isolated areas. This paper propose a development of cloud-based platform for monitoring the isolated PV systems in Ecuador with the aim of develop an extreme scalable solution based on open source software, low consumption wireless sensors, and ‘Software as a Service’ (SaaS) paradigm to process, manage and publish the information for a Ecuadorian solar control center. Keywords: Cloud services, monitoring, photovoltaic systems.

The evolution of the World Wide Web from hypermedia information repositories to web applications such as social networking, wikis or blogs has introduced a new paradigm where users are no longer passive web consumers. Instead, users have become active con- tributors to web applications, so introducing a high level of dynamism in their behavior. Moreover, this trend is even expected to rise in the incoming Web. As a consequence, there is a need to develop new software tools that consider user dynamism in an appropiate and accurate way when generating dynamic workload for evaluating the performance of the current and incoming web. This paper presents a new testbed with the ability of defining and generating web dy- namic workload for e-commerce. For this purpose, we integrated a dynamic workload generator (GUERNICA) with a widely used benchmark for e-commerce (TPC-W).