Estudio comparativo del coeficiente de potencia y de torque presentados en diversas turbinas eólicas

Este artículo presenta un estudio comparativo del coeficiente de potencia y de torque presentado en diversas turbinas eólicas; que se emplean para realizar el análisis de una turbina eólica, estableciendo los conceptos que permiten encontrar la relación de la energía cinética del viento entre la energía mecánica. En este estudio se presentan tres modelos generales que expresan el coeficiente de potencia y de torque, los cuales se agrupan en exponencial, sinusoidal y polinomial. Cabe destacar que los modelos exponenciales y sinusoidales incluyen variaciones en relación a la velocidad específica y del ángulo de ataque; y los modelos polinomiales solo dependen de la velocidad específica. Los modelos son obtenidos considerando características reales de las turbinas eólicas. El propósito de este estudio es analizar el comportamiento de coeficiente de potencia y de torque para establecer todas las consideraciones a tomar en cuenta para el desarrollo e implementación de un emulador de turbinas eólicas.Palabra(s) Clave(s): Coeficiente de Potencia, Coeficiente de Torque, Turbina Eólica

Lung Ultrasound, Clinical and Analytic Scoring Systems as Prognostic Tools in SARS-CoV-2 Pneumonia: A Validating Cohort

At the moment, several COVID-19 scoring systems have been developed. It is necessary to determine which one better predicts a poor outcome of the disease. We conducted a single-center prospective cohort study to validate four COVID-19 prognosis scores in adult patients with confirmed infection at ward. These are National Early Warning Score (NEWS) 2, Lung Ultrasound Score (LUS), COVID-19 Worsening Score (COWS), and Spanish Society of Infectious Diseases and Clinical Microbiology score (SEIMC Score). Our outcomes were the combined variable “poor outcome” (noninvasive mechanical ventilation, intubation, intensive care unit admission, and death at 28 days) and death at 28 days. Scores were analysed using univariate logistic regression models, receiver operating characteristic curves, and areas under the curve. Eighty-one patients were included, from which 21 had a poor outcome, and 9 died. We found a statistically significant correlation between poor outcome and NEWS2, LUS > 15, and COWS. Death at 28 days was statistically correlated with NEWS2 and SEIMC Score although COWS also performs well. NEWS2, LUS, and COWS accurately predict poor outcome; and NEWS2, SEIMC Score, and COWS are useful for anticipating death at 28 days. Lung ultrasound is a diagnostic tool that should be included in COVID-19 patients evaluation

CONTROL DEL FLUJO DE POTENCIA HACIA LA RED ELÉCTRICA DE UN SISTEMA DE GENERACIÓN EÓLICA EMPLEANDO UN GENERADOR DE INDUCCIÓN DE DOBLE ALIMENTACIÓN

ResumenEn este trabajo se presenta el control del flujo de potencia hacia la red eléctrica, a través del Convertidor del Lado de la Red (CLR) de un Sistema de Generación Eólica (SGE), con el objetivo de ser utilizado en un Convertidor Back to Back (CBB) que se requiere conectar a un Generador de Inducción de Doble Alimentación (GIDA). Se diseñan los controladores Proporcionales-Integrales requeridos para controlar la tensión del bus de CD, así como, la Potencia Activa y Potencia Reactiva del SGE. Se simula el CLR en el programa Simulink de Matlab®, donde se valida el funcionamiento del convertidor en los dos modos de operación: como rectificador y como inversor. Aplicando la técnica del control vectorial se obtiene control total en el intercambio de potencias entre el SGE y la red eléctrica.Palabras Claves: Control Vectorial, control proporcional-integral, convertidor del lado de la red, flujo de potencia. CONTROL OF THE POWER FLOW TO THE ELECTRICAL NETWORK OF A WIND GENERATION SYSTEM USING A DOUBLE-FEED INDUCTION GENERATORAbstractIn this paper is presented the control of the power flow to the electrical network, through the Grid-Side Converter (GSC) of a Wind Generation System (WGS) with the objective of being used in a Back to Back Converter that is required to be connected to a Doubly Fed Induction Generator (DFIG). The Proportional-Integral controls are designed in order to control the voltage on the DC Link, as well as, the Active and Reactive Power of the WGS. The GSC is simulated in the program Simulink of Matlab®, where the operation of the converter is validated in the two modes of operation: as a rectifier and as an inverter. Applying the vector control technique is obtained the total control in the power exchange between the WGS and the electrical network.Keywords: Grid side converter, power flow, proportional-integral control, vector control

OBSERVADOR HÍBRIDO DE MODOS DESLIZANTES PARA EL CONTROL SENSORLESS DE UN MOTOR SÍNCRONO DE IMANES PERMANENTES (HYBRID SLIDING MODE OBSERVER FOR SENSORLESS CONTROL OF A PERMANENT-MAGNET SYNCHRONOUS MOTOR)

En este artículo se propone un observador híbrido, el cual está constituido por un observador de Luenberger y un observador de modos deslizantes, ambos funcionando en paralelo para combinar las ventajas de ambas técnicas de observación. Debido a su naturaleza no lineal, este observador es usado para estimar la fuerza electromotriz de un motor síncrono de imanes permanentes, la cual contiene la información de la posición y velocidad. Esta fuerza electromotriz estimada es procesada digitalmente por un algoritmo PLL para estimar la posición y la velocidad del motor. Estas estimaciones son realimentadas en un esquema de control vectorial, con lo cual se elimina la necesidad del sensor mecánico de posición/velocidad (control sensorless). Simulaciones en MATLAB/Simulink son llevadas a cabo, donde se demuestra el correcto funcionamiento del observador propuesto. Finalmente, los resultados obtenidos son analizados y discutidos.In this paper, a hybrid observer is proposed, which is constituted by a Luenberger observer and a sliding mode observer, both working in parallel, so to obtain the advantages of both observation techniques. Due to its nonlinear nature, this observer is used to estimate the back-electromotive force of a permanent magnet synchronous motor, which contains the rotor position and speed information. This estimated back-electromotive force is digitally processed by a PLL algorithm to estimate the motor position and speed. These estimates are feedback into a vector control scheme, where the need for the mechanical position/speed sensor (sensorless control) is eliminated. Simulations in MATLAB/Simulink are carried out, where the performance of the proposed observer is demonstrated. Finally, the results obtained are analyzed and discussed

DISEÑO DE CONVERTIDOR DE CD/CD BOOST OPERANDO EN MODO RED PARA UN SGF PARTICULAR (DC/DC BOOST CONVERTER DESIGN OPERATING IN GRID MODE FOR A PARTICULAR PGS)

Resumen Este trabajo presenta el diseño de un convertidor de CD/CD Boost y la simulación de este en un sistema de generación fotovoltaico (SGF) particular operando en modo red. Para controlar este convertidor, se implementa un control con lazo de realimentación en corriente y un algoritmo para el seguimiento del máximo punto de potencia (MPPT) mediante la técnica de perturbar y observar(P&O). El objetivo de este modo es inyectar potencia activa a la red eléctrica local en función de la capacidad de generación del SGF. El diseño de control para el esquema propuesto se realiza a través de sisotool de MATLAB® en la que se sintoniza y simulan los controladores, posteriormente se prueba el esquema de control propuesto mediante el software PSIM® versión 9.1, en el que se simula el SGF propuesto y se observa el rendimiento del convertidor Boost bajo estas condiciones. Palabras Clave: Convertidor Boost, MATLAB, MPPT; Modo red, Generación fotovoltaica. Abstract This work presents the design of a DC / DC Boost converter and its simulation in a particular photovoltaic generation system (PGS) operating in grid mode. To control this converter, a current feedback loop control and an algorithm for the maximum power point tracking (MPPT) are implemented using the perturb and observe (P&O) technique. The objective of this mode is to inject active power into the local electricity grid based on the generation capacity of the PGS. The control design for the proposed scheme is carried out through MATLAB® sisotool in which the controllers are tuned and simulated, then the proposed control scheme is tested using the PSIM® version 9.1 software, in which the proposed SGF is simulated and the performance of the Boost converter is observed under these conditions Keywords: Boost Converter, MATLAB, MPPT, Grid mode, photovoltaic generation

Evaluation of the Effect of Hydroxyzine on Preoperative Anxiety and Anesthetic Adequacy in Children: Double Blind Randomized Clinical Trial.

Surgical procedures can generate significant preoperative anxiety (POA) in as much as 70% of the paediatric population. The role of hydroxyzine and distractive techniques such as clowns in the management of anxiety is controversial. Our main objective was to evaluate the effect of hydroxyzine on the control of POA. The secondary objective was to assess the potential additive effect of hydroxyzine and distracting techniques. We performed a randomized double-blind, controlled clinical trial in children aged 2–16 years undergoing outpatient surgery (). Subjects were randomized to hydroxyzine (group 1) or placebo (group 2). For the secondary objective, two further groups were made by allocation by chance to hydroxyzine plus accompaniment with clowns (group 3) and placebo plus clowns (group 4). All patients were accompanied by their parents as the standard procedure. POA was determined by a modified Yale scale of POA (m-YPAS). Compliance of children during induction of anesthesia (Induction Compliance Checklist (ICC)) was also assessed. No differences () were found in POA control at the time of induction measured by m-YPAS (group 1: ; group 2: ; group 3: ; group 4: ). No differences were found in the level of ICC between the different treatment arms (group 1: ; group 2: ; group 3: ; group 4: ). The combination of all treatments (group 3) was the only effective strategy to contain the progression of anxiety. In conclusion, hydroxyzine was not effective to control POA in children. The combination of hydroxyzine and clowns avoided the progression of POA in our patients. This trial is registered with ClinicalTrials.gov identifier: NCT03324828 (registered 21 September 2017, subject recruitment started on 12th January 2018).post-print489 K

Pre-operative anxiolysis in children through a combined pharmacological therapy with hydroxyzine and a non-pharmacological distraction technique with a clown (SONRISA): study protocol for randomised double-blind clinical trial.

Background Surgery can generate significant stress and anxiety in up to 70% of the paediatric population. There are several pharmacological and non-pharmacological strategies to reduce pre-operative anxiety in children, however, they have several side effects and the available information about them is contradictory. The role of clowns and hydroxyzine in the management of anxiety is controversial, with some studies supporting and others contraindicating both strategies. Methods We propose a randomised double-blind, controlled clinical trial that will evaluate the effectiveness of both interventions (hydroxyzine and clowns), alone or in combination, to reduce pre-operative anxiety (using the modified Yale scale of preoperative anxiety) in children aged 2–16 years undergoing outpatient surgery (n = 188). Subjects will be randomised into two groups – (1) standard procedure (parental accompaniment) combined with placebo or (2) standard procedure combined with preoperative hydroxyzine. After randomisation, they will be divided by chance into two further groups, depending on the presence of clowns on the patient’s surgery day. Control of pre-operative anxiety will be determined in the four groups by a modified Yale scale of preoperative anxiety and cortisol levels. Compliance of children during induction of anaesthesia, time until anaesthesia recovery, presence of postoperative delirium and use of analgesia until discharge will be also assessed. For additional information, the children, parents and healthcare professionals involved in the study will complete a satisfaction survey. Conclusions This study aims to gather evidence on which of these four therapeutic options achieves the highest reduction of pre-operative anxiety with the best safety profile to allow paediatricians and anaesthesiologists to use the most effective and safe option for their patients.post-print781 K

Mortality and other adverse outcomes in patients with type 2 diabetes mellitus admitted for COVID-19 in association with glucose-lowering drugs: a nationwide cohort study

Background: Limited evidence exists on the role of glucose-lowering drugs in patients with COVID-19. Our main objective was to examine the association between in-hospital death and each routine at-home glucose-lowering drug both individually and in combination with metformin in patients with type 2 diabetes mellitus admitted for COVID-19. We also evaluated their association with the composite outcome of the need for ICU admission, invasive and non-invasive mechanical ventilation, or in-hospital death as well as on the development of in-hospital complications and a long-time hospital stay. Methods: We selected all patients with type 2 diabetes mellitus in the Spanish Society of Internal Medicine's registry of COVID-19 patients (SEMI-COVID-19 Registry). It is an ongoing, observational, multicenter, nationwide cohort of patients admitted for COVID-19 in Spain from March 1, 2020. Each glucose-lowering drug user was matched with a user of other glucose-lowering drugs in a 1:1 manner by propensity scores. In order to assess the adequacy of propensity score matching, we used the standardized mean difference found in patient characteristics after matching. There was considered to be a significant imbalance in the group if a standardized mean difference > 10% was found. To evaluate the association between treatment and study outcomes, both conditional logit and mixed effect logistic regressions were used when the sample size was ≥ 100. Results: A total of 2666 patients were found in the SEMI-COVID-19 Registry, 1297 on glucose-lowering drugs in monotherapy and 465 in combination with metformin. After propensity matching, 249 patients on metformin, 105 on dipeptidyl peptidase-4 inhibitors, 129 on insulin, 127 on metformin/dipeptidyl peptidase-4 inhibitors, 34 on metformin/sodium-glucose cotransporter 2 inhibitor, and 67 on metformin/insulin were selected. No at-home glucose-lowering drugs showed a significant association with in-hospital death; the composite outcome of the need of intensive care unit admission, mechanical ventilation, or in-hospital death; in-hospital complications; or long-time hospital stays. Conclusions: In patients with type 2 diabetes mellitus admitted for COVID-19, at-home glucose-lowering drugs showed no significant association with mortality and adverse outcomes. Given the close relationship between diabetes and COVID-19 and the limited evidence on the role of glucose-lowering drugs, prospective studies are needed

Mortality and other adverse outcomes in patients with type 2 diabetes mellitus admitted for COVID-19 in association with glucose-lowering drugs: a nationwide cohort study

Background: Limited evidence exists on the role of glucose-lowering drugs in patients with COVID-19. Our main objective was to examine the association between in-hospital death and each routine at-home glucose-lowering drug both individually and in combination with metformin in patients with type 2 diabetes mellitus admitted for COVID-19. We also evaluated their association with the composite outcome of the need for ICU admission, invasive and non-invasive mechanical ventilation, or in-hospital death as well as on the development of in-hospital complications and a long-time hospital stay. Methods: We selected all patients with type 2 diabetes mellitus in the Spanish Society of Internal Medicine’s registry of COVID-19 patients (SEMI-COVID-19 Registry). It is an ongoing, observational, multicenter, nationwide cohort of patients admitted for COVID-19 in Spain from March 1, 2020. Each glucose-lowering drug user was matched with a user of other glucose-lowering drugs in a 1:1 manner by propensity scores. In order to assess the adequacy of propensity score matching, we used the standardized mean difference found in patient characteristics after matching. There was considered to be a significant imbalance in the group if a standardized mean difference > 10% was found. To evaluate the association between treatment and study outcomes, both conditional logit and mixed effect logistic regressions were used when the sample size was ≥ 100. Results: A total of 2666 patients were found in the SEMI-COVID-19 Registry, 1297 on glucose-lowering drugs in monotherapy and 465 in combination with metformin. After propensity matching, 249 patients on metformin, 105 on dipeptidyl peptidase-4 inhibitors, 129 on insulin, 127 on metformin/dipeptidyl peptidase-4 inhibitors, 34 on metformin/sodium-glucose cotransporter 2 inhibitor, and 67 on metformin/insulin were selected. No at-home glucose-lowering drugs showed a significant association with in-hospital death; the composite outcome of the need of intensive care unit admission, mechanical ventilation, or in-hospital death; in-hospital complications; or long-time hospital stays. Conclusions: In patients with type 2 diabetes mellitus admitted for COVID-19, at-home glucose-lowering drugs showed no significant association with mortality and adverse outcomes. Given the close relationship between diabetes and COVID-19 and the limited evidence on the role of glucose-lowering drugs, prospective studies are needed

Randomised controlled trial of a prognostic assessment and management pathway to reduce the length of hospital stay in normotensive patients with acute pulmonary embolism

[Background] The length of hospital stay (LOS) for acute pulmonary embolism (PE) varies considerably. Whether the upfront use of a PE prognostic assessment and management pathway is effective in reducing the LOS remains unknown.[Methods] We conducted a randomised controlled trial of adults hospitalised for acute PE: patients were assigned either to a prognostic assessment and management pathway involving risk stratification followed by predefined criteria for mobilisation and discharge (intervention group) or to usual care (control group). The primary end-point was LOS. The secondary end-points were the cost of prognostic tests and of hospitalisation, and 30-day clinical outcomes.[Results] Of 500 patients who underwent randomisation, 498 were included in the modified intention-to-treat analysis. The median LOS was 4.0 days (interquartile range (IQR) 3.7–4.2 days) in the intervention group and 6.1 days (IQR 5.7–6.5 days) in the control group (p<0.001). The mean total cost of prognostic tests was EUR 174.76 in the intervention group, compared with EUR 233.12 in the control group (mean difference EUR −58.37, 95% CI EUR −84.34­ to −32.40). The mean total hospitalisation cost per patient was EUR 2085.66 in the intervention group, compared with EUR 3232.97 in the control group (mean difference EUR −1147.31, 95% CI EUR −1414.97­ to −879.65). No significant differences were observed in 30-day readmission (4.0% versus 4.8%), all-cause mortality (2.4% versus 2.0%) or PE-related mortality (0.8% versus 1.2%) rates.[Conclusions] The use of a prognostic assessment and management pathway was effective in reducing the LOS for acute PE.Peer reviewe