An energy-efficient distributed dynamic bandwidth allocation algorithm for Passive Optical Access Networks

The rapid deployment of passive optical access networks (PONs) increases the global energy consumption of networking infrastructure. This paper focuses on the minimization of energy consumption in Ethernet PONs (EPONs). We present an energy-efficient, distributed dynamic bandwidth allocation (DBA) algorithm able to power off the transmitter and receiver of an optical network unit (ONU) when there is no upstream or downstream traffic. Our main contribution is combining the advantages of a distributed DBA (namely, a smaller packet delay compared to centralized DBAs, due to less time being needed to allocate the transmission slot) with energy saving features (that come at a price of longer delays due to the longer queue waiting times when transmitters are switched off). The proposed algorithm analyzes the queue size of the ONUs in order to switch them to doze/sleep mode when there is no upstream/downstream traffic in the network, respectively. Our results show that we minimized the ONU energy consumption across a wide range of network loads while keeping delay bounded.Postprint (published version

La Educomunicación como base de la formación del graduado en Publicidad: De la teoría a la praxis: Análisis de caso en el Campus María Zambrano

Este Trabajo de Fin de Grado es un recorrido desde la teoría de la Educomunicación hasta la puesta en práctica de la misma. Grandes educadores, y autores teóricos de la talla de Celestein Freinet, Paulo Freire, Howard Gardner, Ken Robinson, Armand Mattelart o Manuel Castells por poner sólo algunos ejemplos, forman parte de un directorio de iniciativas o “buenas prácticas” para llevar a cabo dentro del aula. En el análisis planteado el alumno es visto tanto a nivel individual, como a nivel colectivo, con el fin de dar respuesta a sus necesidades actuales, tomando como referencia la asignatura > impartida en el Grado de Publicidad y RRPP del Campus María Zambrano (Segovia) de la Universidad de Valladolid. Las variables del entorno como las nuevas tecnologías, la comunicación profesor-alumno o la efectividad para la vida profesional y personal del estudiante, son atributos a tener en cuenta. Los profesionales de la comunicación tienen un deber deontológico con los ciudadanos pero, ¿es posible que los ciudadanos asuman un deber con los medios de comunicación? Y lo que es más importante, ¿nuestros jóvenes están preparados para asumir ese deber? Y el maestro… ¡qué pasa con el maestro! ¿Sabría transmitir, potenciar e impulsar dicha cualidad? Preguntas como estas tratan de resolverse en el siguiente proyecto.Grado en Publicidad y Relaciones Pública

A P4-Based PON architecture for 5G

Postprint (author's final draft

A proposal for an SDN-based SIEPON architecture

Passive Optical Network (PON) elements such as Optical Line Terminal (OLT) and Optical Network Units (ONUs) are currently managed by inflexible legacy network management systems. Software-Defined Networking (SDN) is a new networking paradigm that improves the operation and management of networks. In this paper, we propose a novel architecture, based on the SDN concept, for Ethernet Passive Optical Networks (EPON) that includes the Service Interoperability standard (SIEPON). In our proposal, the OLT is partially virtualized and some of its functionalities are allocated to the core network management system, while the OLT itself is replaced by an OpenFlow (OF) switch. A new MultiPoint MAC Control (MPMC) sublayer extension based on the OpenFlow protocol is presented. This would allow the SDN controller to manage and enhance the resource utilization, flow monitoring, bandwidth assignment, quality-of-service (QoS) guarantees, and energy management of the optical network access, to name a few possibilities. The OpenFlow switch is extended with synchronous ports to retain the time-critical nature of the EPON network. OpenFlow messages are also extended with new functionalities to implement the concept of EPON Service Paths (ESPs). Our simulation-based results demonstrate the effectiveness of the new architecture, while retaining a similar (or improved) performance in terms of delay and throughput when compared to legacy PONs.Peer ReviewedPostprint (author's final draft

An integrated SDN-based architecture for Passive Optical Networks

Passive Optical Network (PON) are often managed by non-flexible, proprietary network management systems. Software Defined Networking (SDN) opens the way for a more efficient operation and management of networks. We describe a new SDN-based architecture for Ethernet Passive Optical Networks (EPON), in which some functions of the Optical Line Terminal (OLT) are virtualized and located in an external controller, while keeping the rest of the PON functionality around an Open Flow switch. This opens the way for an improved management of the resource usage, bandwidth allocation, Quality-of-Service (QoS) monitoring and enforcement, or power consumption management, among other possibilities. In order to maintain the time-sensitive nature of the EPON operations, synchronous ports are added to the switch. OpenFlow messages are extended in order to cope with the PON-related parameters. Results based on simulations demonstrate that our proposal performs similarly or better than legacy architectures, in terms of delay and throughput.Postprint (author's final draft

Efecto de la distribución de hidrocarburos SARA sobre las propiedades de residuales de vacío

ResumenCon la finalidad de evaluar el efecto de la composición SARA de residuales de vacío sobre sus propiedades físicoquímicas más importantes, se realizó la separación de tres residuales de vacío de origen venezolano en sus 4 grupos fundamentales: Saturados, Aromáticos, Resinas y Asfaltenos (SARA), preparando a partir de ellos cuatro nuevos residuales, denominados residuales base, con concentraciones másicas de al menos 50% de cada uno de estos grupos, respectivamente. Estos residuales base se caracterizaron a partir de la relación C/H, análisis inmediato, concentraciones de metales pesados y carbón Conradson, encontrándose que para aquellos que contenían altas concentraciones de los grupos saturados y aromáticos, la relación C/H era menor, la proporción de material volátil era mayor y la concentración de metales pesados y de carbón Conradson eran menores que en el caso de los residuales con mayores concentraciones de grupos resínicos y asfalténicos. Se obtuvo además que la posibilidad de craqueo y formación de coque del residual está directamente relacionada con la presencia de estos dos últimos grupos de hidrocarburos en el crudo.AbstractIn order to evaluate the effect of the SARA composition of vacuum residuum on its major physicochemical properties, the separation of three vacuum residuum of Venezuelan origin was done in its four main groups: Saturates, Aromatics, Resins and Asphaltenes (SARA), preparing from these four new residuum, called base residuals, with mass concentrations of each of these groups at least 50%, respectively. These base residuals were characterized in based on the C/H relation, immediate analysis, concentrations of heavy metals and Conradson Carbon, being that for those containing high concentrations of saturated and aromatic groups, C/H relation was lower, volatile material was greater, and the concentration of heavy metals and Conradson carbon were lower than in the case of residuum with higher concentrations of resin and asphaltene groups. Also it was obtained that the possibility of cracking and coke formation of the residuum, is directly related to the presence of the latter two groups in the crude oil

First report of anthracnose caused by Colletotrichum theobromicola on Myrciaria dubia in Brazil.

Plants of the genus Myrciaria are commonly cultivated in the northern region of Brazilfor fruit production. Symptoms of leaf spot in camu-camu (Myrciaria dubia) trees arefrequently observed. The objective of this study was to identify the etiological agentassociated with anthracnose in camu-camu using the concept of morphological andphylogenetic analyses. Leaves with symptoms of anthracnose were collected fromcamu-camu plants in the state of Roraima, Brazil

A QoS-Aware Dynamic Bandwidth Allocation algorithm for passive optical networks with non-zero laser tuning time

The deployment of new 5G services and future demands for 6G make it necessary to increase the performance of access networks. This challenge has prompted the development of new standardization proposals for Passive Optical access Networks (PONs) that offer greater bandwidth, greater reach and a higher rate of aggregation of users per fiber, being Time- and Wavelength-Division Multiplexing (TWDM) a promising technological solution for increasing the capacity by up to 40 Gbps by using several wavelengths. This solution introduces tunable transceivers into the Optical Network Units (ONUs) for switching from one wavelength to the other, thus addressing the ever-increasing bandwidth demands in residential broadband and mobile fronthaul networks based on Fiber to the Home (FTTH) technology. This adds complexity and sources of inefficiency, such as the laser tuning time (LTT) delay, which is often ignored when evaluating the performance of Dynamic Bandwidth Allocation (DBA) mechanisms. We present a novel DBA algorithm that dynamically handles the allocation of bandwidth and switches the ONUs’ lasers from one wavelength to the other while taking LTT into consideration. To optimize the packet delay, we introduce a scheduling mechanism that follows the Longest Processing Time first (LPT) scheduling discipline, which is implemented over the Interleaved Polling with Adaptive Cycle Time (IPACT) DBA. We also provide quality of service (QoS) differentiation by introducing the Max-Min Weighted Fair Share Queuing principle (WFQ) into the algorithm. The performance of our algorithm is evaluated through simulations against the original IPACT algorithm, which we have extended to support multi-wavelengths. With the introduction of LPT, we obtain an improved performance of up to 73% reduction in queue delay over IPACT while achieving QoS differentiation with WFQ.This work has been supported by the Agencia Estatal de Investigación of Spain under project PID2019‐108713RB‐C51/AEI/10.13039/501100011033.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.1 - Desenvolupar infraestructures fiables, sostenibles, resilients i de qualitat, incloent infraestructures regionals i transfrontereres, per tal de donar suport al desenvolupament econòmic i al benestar humà, amb especial atenció a l’accés assequible i equitatiu per a totes les personesObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.4 - Per a 2030, modernitzar les infraestructures i reconvertir les indústries perquè siguin sostenibles, usant els recursos amb més eficàcia i promovent l’adopció de tecnologies i processos industrials nets i racionals ambiental­ment, i aconseguint que tots els països adoptin mesures d’acord amb les capacitats respectivesPostprint (published version

PIGMENTARY UVEITIS ASSOCIATED WITH IRIDOCILIARY CYSTS IN AMERICAN BULLDOGS

Presence of iridociliary cysts may cause a specific form of uveitis not associated with any known systemic disease or underlying cause. The condition was previously characterized in golden retrievers. However, Labrador retrievers, Great Danes and Boston terriers are reported to develop a similar disease condition. The following report documents seven cases of iridociliary cysts, with or without associated pigmentary uveitis, in American bulldogs from Brazil and Spain. Although not an uncommon disease, this syndrome has been relatively infrequently documented in the literature, with only one study in the American bulldog. This article describes clinical findings as well as medical and surgical management of each case. Because some of the patients were closely related in this series, a possible hereditary basis is considered for pigmentary uveitis associated with iridociliary cysts in American bulldogs

Convergence to equilibrium for the discrete coagulation-fragmentation equations with detailed balance

Under the condition of detailed balance and some additional restrictions on the size of the coefficients, we identify the equilibrium distribution to which solutions of the discrete coagulation-fragmentation system of equations converge for large times, thus showing that there is a critical mass which marks a change in the behavior of the solutions. This was previously known only for particular cases as the generalized Becker-D\"oring equations. Our proof is based on an inequality between the entropy and the entropy production which also gives some information on the rate of convergence to equilibrium for solutions under the critical mass.Comment: 28 page