77 research outputs found

    Towards a Versatile Cyber Physical Power System Testbed: Design and Operation Experience

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    The present trends in the area of smartgrids indicate that future transmission and distribution systems will heavily rely on digital and on communication technologies to operate. Indeed, the power systems are evolving progressively towards what is denoted as a cyber-physical system. This transition challenges the classical approaches for experimental testing and requires the development of testing platforms for cyber-physical systems able to capture the interactions between physical components, control and monitoring software and the communication infrastructure. This paper presents general considerations and requirements for a cyber-physical testing platform for power systems. The paper provides also examples of a testing platform specifying the characteristics of the major components and a summary of the experience matured in its setup and configuration. Finally, an example of an experiment on a notional smartgrid and the related results are reported.acceptedVersio

    Identifying Unstable Region of Operation in a Micro-grid System

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    AbstractThis paper presents the stability analysis based on impedance representation of a single phase inverter operating as voltage source, where the Nyquist criteria can be applied. The method can be used to study the stability of a micro-grid dominated by power electronics in isolated operation mode. First, a small signal input impedance model is described. The second methodology applies no energy storage at the AC and DC side of the inverter. For two methods a comparative evaluation with the measured impedance was realized. The obtained results show that the proposed method of no energy storage can be employed in the studies of stability for micro grid systems

    Accuracy Analysis of a Dynamic State Estimator with a Hardware in the Loop Approach

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    State estimation is critical for the monitoring and control of power systems. The conventional approach for state estimation is based on quasi static models for the power systems and as such neglects relevant dynamic effects. These dynamic characteristics are accounted in what are referred as dynamic state estimators (DSE). Several implementations for DSEs have been proposed in literature but mostly focusing on the modelling and numerical aspects. In this paper a laboratory assessment of a DSE for estimating the internal variables of a generation plant is presented. The assessment is conducted with a Hardware in the Loop approach in a laboratory configuration that includes a PDC, real phasor measurement units (PMUs) operating with IEC 61850 sampled values and a real time model of the nordic power system. Experimental results show the behaviour and root mean square error of the estimator for a few different hardware implementations. Thus, it is assessed if the utilization of the IEC 61850 standard may have an impact on performance of the dynamic state estimation and it is quantified the effect on the accuracy.Accuracy Analysis of a Dynamic State Estimator with a Hardware in the Loop ApproachacceptedVersio

    Performance Evaluation of IEC 61850 GOOSE Messages over a 5G Network for Protection Coordination in Smart Grid

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    With low latency communication, it is possible to improve the reliability and reduce the downtime for the electric grids with coordination of digital protection relays. 5G wireless networks are quickly getting better coverage and becoming a viable alternative for smart grid communication. Moreover, there is a significant enthusiasm within the mobile network industry for energy use cases in this context. In this paper, we evaluate the feasibility of using a commercial 5G-NR access network with 4G core for protection coordination using IEC 61850 GOOSE. This is intended to validate previous studies that have evaluated smart grid communication over experimental 5G networks and to give practical insights on how to approach the configuration of protection coordination considering the limitations of the mobile networkPerformance Evaluation of IEC 61850 GOOSE Messages over a 5G Network for Protection Coordination in Smart GridacceptedVersio

    Emlékállítás és felejtés. A „málenkij robot” emlékezete a szatmári sváboknál

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    Commemorative practices and oblivion mechanism. The memory of the deportations of the Satu Mare Swabians) In 1945, a series of violent events took place, bringing the greatest individual and collective trauma in the history of the Satu Mare Swabians. The paper presents the various communication situations in which deportation narratives were drafted and transmitted. I wanted to reveal all the channels in which the commemoration of the deportations (both private and public) took/take place, paying special attention to changes in commemoration forms, as historical phenomena, and also making a comparison between the approaches in the Swabian villages from Romania and Hungary. In commemorating practicesof the deportations I distinguished four levels: individual memory, memory of generations, communicative memory and collective memory, all four having different functions and contexts

    Stability evaluation of a DC micro-grid and future interconnection to an AC system

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    This paper presents the stability analysis of a DC micro-grid fed by renewable sources and the future interconnection with an AC micro-grid. This interconnection is realized through a voltage source converter, and the operation of the micro-grid is in island mode. The stability is analyzed by the Nyquist criteria with the impedance relation method. The frequency response of the models was obtained by the injection of a perturbation current at the operation point. Where this perturbation was at the input of the converter used to export power from the DC grid. Other perturbation was applied at the node of the micro-grid to evaluate its impedance. Finally the simulations show the impedance representation of the systems, and the stability for the interconnection of them. The experimental verification shows the impedance of the converter with the same tendency as the representation obtained by the analytical and simulation

    Resistance to autosomal dominant Alzheimer's disease in an APOE3 Christchurch homozygote: a case report.

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    We identified a PSEN1 (presenilin 1) mutation carrier from the world's largest autosomal dominant Alzheimer's disease kindred, who did not develop mild cognitive impairment until her seventies, three decades after the expected age of clinical onset. The individual had two copies of the APOE3 Christchurch (R136S) mutation, unusually high brain amyloid levels and limited tau and neurodegenerative measurements. Our findings have implications for the role of APOE in the pathogenesis, treatment and prevention of Alzheimer's disease

    Ciencias de la Biología y Agronomía

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    Este volumen I contiene 17 capítulos arbitrados que se ocupan de estos asuntos en Tópicos Selectos de Ciencias de la Biología y Agronomía, elegidos de entre las contribuciones, reunimos algunos investigadores y estudiantes. Se presenta un Estudio Comparativo de los Recursos Hidrológico-Forestales de la Microcuenca de la Laguna de Epatlan, Pue. (1993 a 2014); la Situación Actual de la Mancha de Asfalto en Maíz (Zea mays L.) en los Municipios de Jiquipilas y Ocozocoautla, Chiapas, México; las poblaciones sobresalientes de maíz de la raza Zapalote Chico, en la Región Istmeña de Oaxaca; Se indica el índice de área foliar de cultivo de Chile Poblano mediante dos métodos en condiciones protegidas; Esquivel, Urzúa y Ramírez exploran el efecto de la biofertilización con Azospirillum en el crecimiento y producción de Jitomate; esbozan su artículo sobre la determinación del nivel de Heterosis en híbridos de Maíz para la Comarca Lagunera; una investigación sobre la estabilización de semilla de Solanum lycopersicum durante el almacenamiento y estimulación de la germinación; acotan sobre el CTAB como una nueva opción para la detección de Huanglongbing en cítricos, plantean su evaluación sobre el aluminio y cómo afecta la vida de florero de Heliconia psittacorum; indican sobre el impacto del H-564C, como un híbrido de maíz con alta calidad de proteina para el trópico húmedo de México; presetan su investigación sobre la producción de Piña Cayena Lisa y MD2 (Ananas comosus L.) en condiciones de Loma Bonita, en Oaxaca; acotan sobre el efecto de coberteras como control biológico por conservación contra áfidos en Nogal Pecanero; esbozan sobre la caracterización de cuatro genotipos de Frijol Negro en Martínez de la Torre, Veracruz, México; presentan una caracterización hidroecológica de la microcuenca de Arroyo Prieto, Yuriría, Gto., y alternativas para su restauración ambiental; presentan su investigación sobre el efecto del hongo Beauveria bassiana sobre solubilización de fosfatos y la disponibilidad de fósforo en el suelo; plantean su investigación sobre la Germinación y regeneración in vitro de Epidendrum falcatum LINDL; esbozan su artículo sobre genotipos de frijol negro y su tolerancia a sequía terminal en Veracruz, México

    Particularities of allergy in the Tropics

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    Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

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    Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.
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