Performance comparison between PWM and MPPT charge controllers

Charge controllers are implemented in several electronic systems to protect and control the charge and discharge rates of a battery; for off-grid Photovoltaic (PV) systems, there are two types of technologies, Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT). In this work, we compared two charge controllers in PV systems with the same technical specifications in order to determine the behavior of each of them under similar environmental conditions. The implementation of both charge controllers was based on firmware and hardware with original designs, using PWM and MPPT technologies. Both PV systems are composed of the charge controller, a 30 W solar panel and a 12 V – 18 Ah battery; in the experimental tests we measured the voltage and current in the panel and the battery in charge and discharge processes, observing that the MPPT controller has a higher average efficiency than the PWM controller, elucidating that the type of technology used in the charge controller has a direct impact on the efficiency, even under unfavorable conditions of solar radiation and environmental temperature. The PWM controller is an option of acceptable efficiency and lower price in relation to the MPPT controller. In the implementation of both controllers we calculated similar periods of autonomy

Performance comparison between PWM and MPPT charge controllers

Charge controllers are implemented in several electronic systems to protect and control the charge and discharge rates of a battery; for off-grid Photovoltaic (PV) systems, there are two types of technologies, Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT). In this work, we compared two charge controllers in PV systems with the same technical specifications in order to determine the behavior of each of them under similar environmental conditions. The implementation of both charge controllers was based on firmware and hardware with original designs, using PWM and MPPT technologies. Both PV systems are composed of the charge controller, a 30 W solar panel and a 12 V – 18 Ah battery; in the experimental tests we measured the voltage and current in the panel and the battery in charge and discharge processes, observing that the MPPT controller has a higher average efficiency than the PWM controller, elucidating that the type of technology used in the charge controller has a direct impact on the efficiency, even under unfavorable conditions of solar radiation and environmental temperature. The PWM controller is an option of acceptable efficiency and lower price in relation to the MPPT controller. In the implementation of both controllers we calculated similar periods of autonomy

Geometric tree graphs of points in convex position

Given a set $P$ of points in the plane, the geometric tree graph of $P$ is defined as the graph $T(P)$ whose vertices are non-crossing rectilinear spanning trees of $P$, and where two trees $T_1$ and $T_2$ are adjacent if $T_2 = T_1 -e+f$ for some edges $e$ and $f$. In this paper we concentrate on the geometric tree graph of a set of $n$ points in convex position, denoted by $G_n$. We prove several results about $G_n$, among them the existence of Hamilton cycles and the fact that they have maximum connectivity

Controlador de carga MPPT con método de estimación del estado de carga basado en conteo de amperios hora y voltaje a circuito abierto

Context:  Off-grid photovoltaic systems are one of the main alternatives to fulfill the need for electricity in rural areas where the connection to traditional electrification systems is not possible. Among the components of a photovoltaic off-grid system, the charge controller must adapt the voltage and current levels to store the energy delivered by the panels in batteries. Method: In this work, a maximum power point tracking (MPPT) charge controller based on the Perturbation and Observation (P&O) technique was implemented and evaluated. Additionally, the state of charge of the battery was estimated by combining the ampere-hour counting method and the open-circuit voltage. The controller implements a two-phase charging algorithm for lead-acid batteries. Results: The developed charge controller obtained an average efficiency of 84,7% and reached a maximum value of 96,3%. In addition, the two-phase charging algorithm and the state of charge estimation method implemented in the controller allowed for the adequate control and monitoring of the battery charging and discharging processes. ConConclusions: The proposed charge controller follows the maximum power point of the solar panel and allows storing energy in lead-acid batteries while supervising their state of charge.Contexto: Los sistemas fotovoltaicos desconectados de la red son una de las principales alternativas para suplir la necesidad de electricidad en zonas rurales donde la conexión a los sistemas tradicionales de electrificación no es posible. Entre los componentes del sistema fotovoltaico, el controlador de carga debe adaptar los niveles de corriente y voltaje para almacenar en baterías la energía entregada por los paneles. Método: En este trabajo se implementó y evaluó un controlador de carga de seguimiento del punto de máxima potencia (MPPT) basado en la técnica de perturbación y observación (P&O). Adicionalmente, se estimó el estado de carga de la batería combinando los métodos de conteo de amperios-hora y voltaje de circuito abierto. El controlador implementa un algoritmo de carga de dos fases para baterías de ácido-plomo. Resultados: El controlador de carga desarrollado obtuvo una eficiencia promedio de 84,7 % y alcanzó un valor máximo de 96,3 %. Adicionalmente, el algoritmo de carga de dos fases y el método de estimación del estado de caga implementados en el controlador permitieron un control adecuado y monitoreo de los procesos de carga y descarga de la batería. Conclusiones: El controlador de carga propuesto sigue el punto de máxima potencia del panel solar y permite almacenar energía en baterías de ácido-plomo a la vez que monitorea el estado de carga de estas

Consenso colombiano de enfermedad inflamatoria intestinal

La Enfermedad inflamatoria intestinal (EEI) es un término con el que se conocen varias entidades, las dos más importantes: la colitis ulcerativa idiopática (CUI) y la enfermedad de Crohn (EC), cuyo origen es multifactorial y se caracterizan por un fenómeno inflamatorio, crónico, recurrente, con diferentes grados de severidad del tubo digestivo; pero, además con afectación potencial de otros órganos. En la última década ha habido un renovado interés en dichas entidades, debido a un auge en medicamentos novedosos; a pesar de lo cual estas siguen siendo incurables. Lo anterior asociado a una incidencia creciente de dicha patología en nuestro país nos obliga tanto científica como moralmente a convocar a un panel de expertos para elaborar unos lineamientos básicos en el enfoque y manejo de la EEI. OBJETIVOS 1. Desarrollar un consenso adaptado a nuestro medio, basado en documentación científica de la mejor calidad disponible para el enfoque diagnóstico y el manejo médico y quirúrgico. 2. Publicar y difundir dichos lineamentos tanto a la comunidad científica como al público en general a través de foros especializados, y medios de comunicación de alta penetración. 3. Elaborar y divulgar el consenso en forma de suplemento de la Revista Colombiana de Gastroenterología, el 8 de diciembre de 2011, en medio del congreso de ACADI (Asociación Colombiana de Asociaciones del Aparato Digestivo); es el mejor homenaje que el panel multidisciplinario de expertos le puede rendir a dicho evento; pero más importante aún es el reconocimiento que se le hace a los pacientes que padecen de dicha patología en nuestro país, quienes en últimas son nuestra razón de ser. METODOLOGÍA 1. Se invitaron médicos especialistas (Clínicos y quirúrgicos), líderes de opinión e industria farmacéutica nacional, cuyo área de interés y de trabajo es la EEI. 2. Se separó y manejó independientemente desde el principio la CUI de la EC. A su vez, se dividió cada entidad por módulos, con base en el método de panel de Delphi, se nombró un coordinador por cada uno de ellos, el cual se encargó de analizar junto con su equipo la literatura, para extraer el nivel de evidencia clínica y así emitir unos conceptos preliminares. Posteriormente, todo el panel de expertos se reunió en varias jornadas y conjuntamente se revisó nuevamente la evidencia clínica y conclusiones de los diferentes módulos homogenizándolas y de una manera concertada se formularon las recomendaciones definitivas.Q4https://orcid.org/0000-0002-9219-4548Revista Nacional - Indexad

Effectiveness of an intervention for improving drug prescription in primary care patients with multimorbidity and polypharmacy:Study protocol of a cluster randomized clinical trial (Multi-PAP project)

This study was funded by the Fondo de Investigaciones Sanitarias ISCIII (Grant Numbers PI15/00276, PI15/00572, PI15/00996), REDISSEC (Project Numbers RD12/0001/0012, RD16/0001/0005), and the European Regional Development Fund ("A way to build Europe").Background: Multimorbidity is associated with negative effects both on people's health and on healthcare systems. A key problem linked to multimorbidity is polypharmacy, which in turn is associated with increased risk of partly preventable adverse effects, including mortality. The Ariadne principles describe a model of care based on a thorough assessment of diseases, treatments (and potential interactions), clinical status, context and preferences of patients with multimorbidity, with the aim of prioritizing and sharing realistic treatment goals that guide an individualized management. The aim of this study is to evaluate the effectiveness of a complex intervention that implements the Ariadne principles in a population of young-old patients with multimorbidity and polypharmacy. The intervention seeks to improve the appropriateness of prescribing in primary care (PC), as measured by the medication appropriateness index (MAI) score at 6 and 12months, as compared with usual care. Methods/Design: Design:pragmatic cluster randomized clinical trial. Unit of randomization: family physician (FP). Unit of analysis: patient. Scope: PC health centres in three autonomous communities: Aragon, Madrid, and Andalusia (Spain). Population: patients aged 65-74years with multimorbidity (≥3 chronic diseases) and polypharmacy (≥5 drugs prescribed in ≥3months). Sample size: n=400 (200 per study arm). Intervention: complex intervention based on the implementation of the Ariadne principles with two components: (1) FP training and (2) FP-patient interview. Outcomes: MAI score, health services use, quality of life (Euroqol 5D-5L), pharmacotherapy and adherence to treatment (Morisky-Green, Haynes-Sackett), and clinical and socio-demographic variables. Statistical analysis: primary outcome is the difference in MAI score between T0 and T1 and corresponding 95% confidence interval. Adjustment for confounding factors will be performed by multilevel analysis. All analyses will be carried out in accordance with the intention-to-treat principle. Discussion: It is essential to provide evidence concerning interventions on PC patients with polypharmacy and multimorbidity, conducted in the context of routine clinical practice, and involving young-old patients with significant potential for preventing negative health outcomes. Trial registration: Clinicaltrials.gov, NCT02866799Publisher PDFPeer reviewe

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R$^{2}$ = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R$^{2}$ = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

AimAmazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.LocationAmazonia.TaxonAngiosperms (Magnoliids; Monocots; Eudicots).MethodsData for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.ResultsIn the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.Main ConclusionNumerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions