Alternative Multiple Spanning Tree Protocol (AMSTP) for Optical Ethernet Backbones

The availability and affordable cost of Gigabit and 10 Gigabit Ethernet switches has impacted the deployment of metropolitan area networks (MAN) and campus networks. This paper presents a new protocol, the alternative multiple spanning tree protocol (AMSTP), that uses multiple source based spanning trees for backbones using Ethernet switches. It provides minimum paths and more efficient usage of optical backbone infrastructure than currently proposed protocols such as resilient packet ring and rapid spanning tree. The protocol exhibits features similar to MAC routing protocols like Link State Over MAC (LSOM) such as optimum path and effective infrastructure usage, without requiring MAC routing due to the use of the spanning tree protocol paradigm. AMSTP is not restricted to specific topologies such as ring or tree, but performs efficiently in arbitrary topologies. Among the application areas are optical backbones of campus and MANs.Publicad

Inclusive Development in Latin America and Smallholders’ Interactive Learning Spaces

Inclusive development appears as a challenge in Latin America countries after the rupture of the social inclusion as a trickle-down effect of the economic growth. Searching development with inclusion several public policies were implemented in Latin American focusing in the agri-food production. In order to assess the progress to reach such objectives, two cases are studied. Smallholder milk producers at the Loma Blanca community (Mexico) and smallholders olive producers at Aimogasta (Argentina) were considered. Interactive learning spaces were clearly identified as consequence of the linking between product, producers and territory. Despite these results, several queries are still opened.Fil: Bastida Mercado, Claudia. Universidad Autónoma del Estado de México; MéxicoFil: García Martínez, Anastacio. Universidad Autónoma del Estado de México; MéxicoFil: Sanchez, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Estudios Urbanos y Regionales; Argentina. Universidad de Morón; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentin

A comparative study of different optimization methods for resonance half-bridge converter

The LLC resonance half-bridge converter is one of the most popular DC-DC converters and could easily inspire researchers to design a high-efficiency and high-power-density converter. LLC resonance converters have diverse operation modes based on switching frequency and load that cause designing and optimizing procedure to vary in different modes. In this paper, different operation modes of the LLC half-bridge converter that investigate different optimization procedures are introduced. The results of applying some usual optimization methods implies that for each operation mode some specific methods are more appropriate to achieve high efficiency. To verify the results of each optimization, numerous simulations are done by Pspice and MATLAB and the efficiencies are calculated to compare them. Finally, to verify the result of optimization, the experimental results of a laboratory prototype are provided.Peer ReviewedPostprint (published version

"Agua dulce, agua salada". propuestas y problemas del análisis arqueológico del recurso hídrico en Al-Andalus

Jornadas de Jóvenes en Investigación Arqueológica, JIA (3as : 5-7 de mayo 2010 : Universitat Autònoma de Barcelona). Sesión 9. La explicación de la Edad Media a través de la Arqueología.Ante la inmensidad del tema que pretendemos analizar hemos planteamos en este trabajo únicamente algunos juicios de valor historiográficos y nuestra breve experiencia hasta el momento. La escasez de espacio, además, nos obliga a sintetizar sobremanera un tema tan complejo y de tal profundidad que ha centrado en gran medida los debates histórico-arqueológicos sobre al-Andalus, llegando a afirmarse que es "algo más que una discusión historiográfica" (Malpica, 1995: 67).Given the vastness of the topic that we analyze in this paper we propose only some historiographical value judgments and our brief experience so far. Shortage of space also forces us to synthesize an extremely complex issue and of such depth that has focused largely historical and archaeological discussions about al-Andalus, even claiming it is "more than a historiographical discussion (Malpica, 1995: 67).Davant la immensitat del tema que pretenem analitzar hem plantegem en aquest treball únicament alguns judicis de valor historiogràfics i la nostra breu experiència fins al moment. L'escassetat d'espai, a més, ens obliga a sintetitzar gran manera un tema tan complex i de tal profunditat que s'ha centrat en gran mesura els debats històric-arqueològics sobre al-Andalus, arribant a afirmar que és "quelcom més que una discussió historiogràfica" (Malpica, 1995: 67)

A novel high step-up secondary side impedance source full-bridge converter

In order to suppress the voltage stress of semiconductor devices, and solve the reverse recovery problem of diodes by decreasing the duty cycle of switches, impedance source converters could be consider as a solution. In this paper an impedance network is applied to the secondary side of a phase-shifted full-bridge converter in order to reduce the voltage stress of rectifier diodes. The proposed impedance network involves coupled inductors and capacitors that provide a new rectifier configuration for the converter. Operational principles of the proposed converter along with its theoretical analysis is investigated, and finally simulation results is provided by Pspice to verify the performance of the converter.Postprint (published version

Component sizing of an isolated networked hybrid microgrid based on operating reserve analysis

The power-sharing possibility amongst microgrids (MGs) in networked microgrids (NMGs) offers multiple profits to the NMG by employing an applicable energy management system. An efficient energy management system can provide an adequate compromise in terms of the component sizing of NMGs through MG collaboration. This paper proposes a procedure to size the component for an isolated networked hybrid microgrid. The proposed design procedure relies on the optimum operation of individual MGs. The defined Reduced Factor (RF) identifies the possible size reduction for the dispatchable components, such as diesel generators and the energy storage system of each MG. The introduced RF is based on the operating reserve evaluation obtained from the optimal operation of individual MGs and the correlation between load profiles. Eventually, the simulation and practical results of a networked hybrid MG consisting of three MGs are presented to verify the proposed component sizing procedure. The practical results verify the theoretical expectations. The results show that NPC and capital costs are reduced up to 13% and 17%, respectively.The authors would like to thank the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN)—Agencia Estatal de Investigación (AEI) and the European Regional Development Funds (ERDF) by grant PGC2018-098946-B-I00 funded by MCIN/AEI/10.13039/501100011033/ and by ERDF A way of making Europe.Peer ReviewedPostprint (published version

Networked microgrid energy management based on supervised and unsupervised learning clustering

Networked microgrid (NMG) is a novel conceptual paradigm that can bring multiple advantages to the distributed system. Increasing renewable energy utilization, reliability and efficiency of system operation and flexibility of energy sharing amongst several microgrids (MGs) are some specific privileges of NMG. In this paper, residential MGs, commercial MGs, and industrial MGs are considered as a community of NMG. The loads’ profiles are split into multiple sections to evaluate the maximum load demand (MLD). Based on the optimal operation of each MG, the operating reserve (OR) of the MGs is calculated for each section. Then, the self-organizing map as a supervised and a k-means algorithm as an unsupervised learning clustering method is utilized to cluster the MGs and effective energy-sharing. The clustering is based on the maximum load demand of MGs and the operating reserve of dispatchable energy sources, and the goal is to provide a more efficient system with high reliability. Eventually, the performance of this energy management and its benefits to the whole system is surveyed effectively. The proposed energy management system offers a more reliable system due to the possibility of reserved energy for MGs in case of power outage variation or shortage of power.Peer ReviewedPostprint (published version

Spider diversity (Arachnida: Araneae) in two different coffee management systems and surrounding tropical forest during two contrasting seasons in Oaxaca, Mexico

This study focuses on species richness, abundance, diversity, and seasonal variation of spiders in two coffee plantations with different crop management and a portion of tropical forest in two municipalities of La Costa region of Oaxaca, Mexico, using manual collection, foliage beating and pitfall traps. We collected 2,210 spiders belonging to 35 families, 100 genera and 146 species. The inventory includes 51 new species records for Oaxaca. Completeness values for two estimators indicate that the level of representation of inventories range from 68.25% to 78.44%, and the proportion of singletons range from 33.72% to 38.14%. Spider abundance in the rainy season was significantly lower than during the dry season. Spider abundance in the Tropical Forest was significantly lower than Monoculture site with the foliage beating method. Polyculture was the site with the lowest spider abundance with the pitfall traps. Rarefaction curves did not show significant differences in species richness between the sites and seasons. Hutcheson t-test showed that spider diversity was significantly lower in Monoculture than Tropical Forest during the rainy season. This study contributes to the knowledge of the arachnofauna of Mexico and particularly of the state of Oaxaca.Este estudio se enfoca en la riqueza de especies, abundancia, diversidad y variación estacional de las arañas en dos cultivos de café con diferente manejo y una porción de bosque tropical en dos municipios de la región Costa de Oaxaca, México, utilizando la colecta manual, agitación del follaje y trampas de caída. Se recolectaron 2,210 arañas pertenecientes a 35 familias, 100 géneros y 146 especies. El inventario incluye 51 nuevos registros de especies para Oaxaca. Los valores de completitud de dos estimadores indican que el nivel de representación de los inventarios oscila entre el 68.25 % y el 78.44 %, mientras que la proporción de singletons fue de 33.72 % y 38.14 %. La abundancia de arañas en la estación lluviosa fue significativamente menor que durante la estación secas. La abundancia de arañas en el Bosque Tropical fue significativamente menor que en el Monocultivo con el método de agitación de follaje. El Policultivo fue el sitio con menor abundancia de arañas con el método de trampas de caída. Las curvas de rarefacción no mostraron diferencias significativas en la riqueza de especies entre los sitios y estaciones. La prueba t de Hutcheson mostró que la diversidad de arañas fue significativamente menor en el Monocultivo que en el Bosque Tropical durante la estación lluviosa. Este estudio contribuye al conocimiento de la aracnofauna de México y particularmente del estado de Oaxaca

Inverter control analysis in a microgrid community based on droop control strategy

Power-sharing in a microgrid community (MGC) requires mandatory strategies in order to stabilize the system by maintaining the rated frequency and voltage. The hierarchical control strategy is the most adopted control structure due to providing seamless operation in transient between islanded and grid-connected modes. Droop control strategy is discussed in this paper to control the voltage source inverter (VSI) in power exchange mode with other microgrids (MGs) or main utility grid. After analysing the average model of three-phase VSI, the voltage and current transfer functions are obtained according to the considered droop controller. The stability and seamless operation of the system are analysed, and the simulation results verify the control loops of the VSI can handle the power variation of the MG effectively.This work has been partially supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN)-Agencia Estatal de Investigación (AEI) and the European Regional Development Funds (FEDER), by project PGC2018-098946-B-I00.Peer ReviewedPostprint (published version