Multi-layered solid-PCM thermocline thermal storage concept for CSP plants. Numerical analysis and perspectives

Thermocline storage concept has been considered for more than a decade as a possible solution to reduce the huge cost of the storage system in concentrated solar power (CSP) plants. However, one of the drawbacks of this concept is the decrease in its performance throughout the time. The objective of this paper is to present a new thermocline-like storage concept, which aims at circumventing this issue. The proposed concept consists of a storage tank filled with a combination of solid material and encapsulated PCMs, forming a multi-layered packed bed, with molten salt as the heat transfer fluid. The performance evaluation of each of the prototypes proposed is virtually tested by means of a detailed numerical methodology which considers the heat transfer and fluid dynamics phenomena present in these devices. The virtual tests carried out are designed so as to take into account several charging and discharging cycles until periodic state is achieved, i.e. when the same amount of energy is stored/released in consecutive charging/discharging cycles. As a result, the dependence of the storage capacity on the PCMs temperatures, the total energy and exergy stored/released, as well as the efficiencies of the storing process are compared for the different thermocline, single PCM, cascaded PCM and the proposed multi-layered solid-PCM (MLSPCM) configurations. The analysis shows that the multi-layered solid-PCM concept is a promising alternative for thermal storage in CSP plants.Peer ReviewedPostprint (author’s final draft

Advanced Videoconferencing based on WebRTC

Lately, videoconference applications have experienced an evolution towards the World Wide Web. New technologies have given browsers real-time communications capabilities. In this context, WebRTC aims to provide this functionality by following and defining standards. Being a new effort, WebRTC still lacks advanced videoconferencing services such as session recording, media mixing and adjusting to varying network conditions. This paper analyzes these challenges and proposes an architecture based on a traditional communications entity, the Multipoint Control Unit or MCU as a solution

Predictive Power Control for PV Plants With Energy Storage

This work presents a model predictive control (MPC) approach to manage in real-time the energy generated by a grid-tied photovoltaic (PV) power plant with energy storage (ES), optimizing its economic revenue. This MPC approach stands out because, when a long enough prediction horizon is used, the saturation of the ES system (ESS) can be advanced by means of a prediction model of the PV panels production. Therefore, the PV+ES power plant can modify its production so as to manage the power deviations with regard to that committed in the daily and intraday electricity markets, with the objective of reducing economic penalties. The initial power commitment is supposed in this work to be given by a higher level energy management operator. By a proper definition of its objective function, the predictive control allows us to economically optimize the PV+ES power plant performance. This control strategy is tested in simulations with actual data measured for different days with varying meteorological conditions. Results provide a good reference on the economic benefits which can be obtained thanks to the MPC introduction

dOTM: a mechanism for distributing centralized multi-party video conferencing in the cloud

One of the key factors for a given application to take advantage of cloud computing is the ability to scale in an efficient, fast and reliable way. In centralized multi-party video conferencing, dynamically scaling a running conversation is a complex problem. In this paper we propose a methodology to divide the Multipoint Control Unit (the video conferencing server) into more simple units, broadcasters. Each broadcaster receives the media from a participant, processes it and forwards it to the rest. These broadcasters can be distributed among a group of CPUs. By using this methodology, video conferencing systems can scale in a more granular way, improving the deployment

Implementation of integrated systems for efficient resource planning in hospitals

Objetivo: evaluar el impacto de la implantación de Sistemas de Información Integrados para la planificación de recursos empresariales en hospitales, mediante el análisis de su diseño y utilización, con especial atención a la satisfacción de los usuarios. Métodos: investigación cualitativa basada en un estudio de caso longitudinal. Para la recogida de la información se utilizaron las técnicas de observación no participante, análisis de documentación interna, entrevistas individuales y en grupo y conversaciones informales. La unidad de análisis fue una Fundación Hospitalaria de la Comunidad Autónoma de Madrid seleccionada de manera intencional por su adecuación al objetivo del trabajo y por la facilidad de acceso a la información. Resultados: las expectativas previas de los responsables del hospital se cumplieron razonablemente. Se consiguió un sistema único con distintos módulos en el que la información está integrada. Los usuarios están satisfechos con el funcionamiento del sistema, especialmente el personal clínico. Gracias a la implicación de la dirección y de los mandos intermedios, se minimizaron las dificultades derivadas de los roces entre la cultura clínica y la administrativa durante el proceso de implantación y en la utilización posterior del sistema. Conclusiones: la aplicación de Sistemas de Información Integrados en los hospitales no solo es posible, sino que resulta muy conveniente. Para la Fundación Hospitalaria supone una mejora de la eficacia en la gestión clínico asistencial y un aumento de la eficiencia en la gestión económico financiera. La implantación generalizada de estos sistemas permitiría establecer comparaciones entre distintos hospitales y avanzar hacia la gestión integral del sistema sanitario.Objective: to evaluate the impact of the setting up of the enterprise resource planning in hospitals, by analysing their design and implementation, paying special attention to the user satisfaction. Methods: qualitative research study based on a longitudinal case study in which the techniques of internal documentation analysis, non-participant observation, individual and group interviews and informal talks were used to collect data. The analysis unit was selected because of its suitability for the objective of the paper and easy access to the necessary information. Specifically, the study has been conducted in "Fundación Hospitalaria de la Comunidad de Madrid (FHM)". Results: the hospital management's prior expectations of the system were fulfilled to a reasonable degree. A single system, with different modules in which the information is integrated, has been achieved. The users, especially the clinical staff, are satisfied with the operation of the system. Thanks to the involvement of the senior and middle managers, it has been possible to minimise the difficulties arising from confrontation between the clinical and the administrative cultures during the process of the setting-up and subsequent utilisation of the system. Conclusions: the implementation of enterprise resource planning in hospitals is not only possible but also very advantageous. For the Fundación Hospitalaria de Madrid, it represents not only improved effectiveness in clinical assistance management but also higher efficiency in economic and financial resources management. If these systems were established generally, it would be possible to make constructive comparisons between different hospitals, and to progress towards the integral management of the health-care system

Videoconference capacity Leasing on Hybrid Clouds.

This paper proposes a new methodology focused on implementing cost effective architectures on Cloud Computing systems. With this methodology the paper presents some disadvantages of systems that are based on single Cloud architectures and gives some advices for taking into account in the development of hybrid systems. The work also includes a validation of these ideas implemented in a complete videoconference service developed with our research group. This service allows a great number of users per conference, multiple simultaneous conferences, different client software (requiring transcodification of audio and video flows) and provides a service like automatic recording. Furthermore it offers different kinds of connectivity including SIP clients and a client based on Web 2.0. The ideas proposed in this article are intended to be a useful resource for any researcher or developer who wants to implement cost effective systems on several Cloud

Propuesta de trabajo de curso: tipo de evaluación final para la asignatura matemática numérica en la universidad de las ciencias informáticas

Esta investigación presenta una propuesta de trabajo de curso como tipo de evaluación final para la asignatura de Matemática Numérica del ingeniero informático de la Universidad de las Ciencias Informáticas de Cuba. En esta actividad se produce la integración interdisciplinaria de la Matemática con asignaturas que se imparten en años precedentes y en el propio segundo año de la carrera, con el objetivo de elevar la formación integral de los estudiantes a través del desarrollo de habilidades técnico-profesionales, que permitirá a los educandos cumplir mejor con su encargo social

Pyrrole Functionalization by Copper‐Catalyzed Nitrene Transfer Reactions

The catalytic functionalization of pyrroles by incorporation of a nitrene group is reported. The Cα‐H bond of 1H‐pyrrole is amidated upon the formal insertion of the NTs (Ts=p‐toluenesulfonyl) group catalyzed by TpBr3Cu(NCMe) (TpBr3=hydrotris(3,4,5‐tribromo‐pyrazolyl)borate). N‐substituted pyrroles also verify the same transformation. The mechanism proposal is similar to that previously described for benzene amidation with the same catalyst and PhI=NTs, which takes place through aziridine formation, ring opening and 1,2‐hydrogen shift. A cascade reaction involving the coupling of 2,5‐dimethylfuran, 1,2,3‐trimethyl‐pyrrole and a nitrene NTs group is also described, leading to a 1,2‐dihydropyridine‐imine compound.Support for this work was provided by the MINECO (CTQ2017‐82893‐C2‐1‐R and PO FEDER 2014‐2020, UHU‐1254043). AMR and MRR thanks MEC for a FPU fellowships