Técnica de control de rápida respuesta dinámica para convertidores DC/DC integrados de alta frecuencia (5MHz)

Una frecuencia de conmutación de 5MHz permite la integración en un chip de un convertidor DC/DC de baja potencia (10W). Aunque a esta frecuencia de conmutación es posible emplear un control modo tensión con un ancho de banda de 1MHz, los efectos parásitos y la robustez del sistema no permiten esa frecuencia de ancho de banda tan elevada. En esta publicación se propone una técnica de control que optimiza la respuesta dinámica de convertidores DC/DC de elevada frecuencia de conmutación. El control propuesto y analizado se basa en el control modo corriente de pico de la corriente del condensador de salida de un convertidor reductor (Buck). El lazo de corriente del condensador de salida proporciona la rápida respuesta dinámica, ya que se comporta como un feed-forward de la corriente por la carga, mientras que el lazo de tensión proporciona regulación y exactitud en régimen permanente. Los resultados experimentales han validado la rápida respuesta dinámica del control frente a escalones de carga

Fast control technique based on peak current mode control of the output capacitor current

The control proposed and analyzed in this paper is based on the peak current mode control of the output capacitor current of a Buck converter. The output capacitor current loop provides fast dynamic response to the control since it behaves as a feed-forward of the load current while the voltage loop provides accurate steady state regulation. A simulation oriented averaged model of the proposed control has been developed to design the external voltage loop. As shown in simulations, with the converter switching at 5 MHz, the proposed control with a voltage loop of 50 kHz bandwidth has the same voltage drop and a similar dynamic response as a 1 MHz bandwidth voltage mode control. The reduction of the bandwidth makes easier the control implementation and integration. Finally, experimental results have been achieved verifying the fast dynamic response of the proposed control under load step

Fast control technique for high frequency (5MHz) DC/DC integrated converter

A switching frequency of 5 MHz allows the integration in a chip of a low power (10W) DC/DC converter. Although this switching frequency would make feasible a voltage mode control with 1MHz bandwidth, the parasitics and robustness don't allow such a high frequency bandwidth. This paper proposes a fast control technique that helps to optimize the dynamic response of high frequency DC/DC converter. The control proposed and analyzed in this paper is based on the peak current mode control of the output capacitor current of a Buck converter. The output capacitor current loop provides fast dynamic response to the control since it behaves as a feed-forward of the load current while the voltage loop provides accurate steady state regulation. Experimental results have validated the fast dynamic response of the proposed control under load steps

Fast control technique for high frequency DC/DC integrated converter based on non-invasive output capacitance current estimation

High switching frequency allows the integration of low power DC/DC converters. Although a high switching frequency would make feasible a voltage mode control with 1MHz bandwidth, parasitic effects and robustness don’t allow such a high bandwidth. This paper proposes a fast control to optimize the dynamic response of high frequency DC/DC converters. The proposed control is based on the peak current mode control of the output capacitor current. The output capacitor current loop provides fast dynamic response while the voltage loop provides accurate steady state regulation. Experimental results have validated the fast dynamic response of the proposed control under load step

V2ic Control: A Novel Control Technique with Very Fast Response under Load and Voltage Steps

High switching frequencies (several MHz) allow the integration of low power DC/DC converters. Although, in theory, a high switching frequency would make possible to implement a conventional voltage mode control with very high bandwidth, in practice, parasitic effects and robustness make very complex to achieve bandwidths higher than 1MHz. This paper proposes a fast control technique to optimize the dynamic response of high switching frequency DC/DC converters. The proposed control is based on two loops. The fast internal loop has information of the output capacitor current and the error voltage, providing fast dynamic response under load and output voltage reference steps, while the slow external voltage loop provides accurate steady state regulation. Experimental results validate the fast dynamic response of the proposed control under load and output voltage reference steps and its suitability for high switching frequencies

Thermostructural characterization and structural elastic property optimization of novel high luminosity LHC collimation materials at CERN

The CERN Large Hadron Collider is currently being upgraded to operate at a stored beam energy of 680 MJ through the High Luminosity upgrade. The LHC performance is dependent on the functionality of beam collimation systems, essential for safe beam cleaning and machine protection. A dedicated beam experiment at the CERN High Radiation to Materials facility is created under the HRMT-23 experimental campaign. This experiment investigates the behavior of three collimation jaws having novel composite absorbers made of copper diamond, molybdenum carbide graphite, and carbon fiber carbon, experiencing accidental scenarios involving the direct beam impact on the material. Material characterization is imperative for the design, execution, and analysis of such experiments. This paper presents new data and analysis of the thermostructural characteristics of some of the absorber materials commissioned within CERN facilities. In turn, characterized elastic properties are optimized through the development and implementation of a mixed numerical-experimental optimization technique.peer-reviewe

Vocational education teacher’s perceptions about adequacy TECO’s curriculum to the current needs of adventure tourism companies

El currículo del ciclo formativo de grado medio en conducción de actividades físico-deportivas en el medio natural (TECO) tiene más de 20 años de anti-güedad (perteneciendo todavía al sistema LOGSE), siendo el sector del turismo activo y un contexto empresarial en continuo desarrollo y crecimiento (Inglés, Funollet y Olivera, 2016). El objetivo delpresente estudio es conocer la percepción del profe-sorado de TECO sobre la adecuación del currículo LOGSE vigente respecto al contexto empresarial de turismo activo. Se ha realizado un estudio con un diseño no experimental, descriptivo y seccional, debido a las características de la muestra compues-ta por 50 profesores de TECO de ámbito nacional con los que se ha contactado. Para la obtención de los datos, se utilizó un cuestionario ad hoc, al que se le realizó una validación de contenido mediante el consenso de 10 jueces expertos (7 profesores de TECO y 3 profesores de universidad).A partir de las valoraciones de los expertos, se confeccionó un segundo cuestionario finalmente empleado con 6 preguntas principales (y algunas subpreguntas den-tro de ellas), como por ejemplo" ¿Crees que la ac-tual titulación LOGSE es acorde con lo que le ofrece tu entorno laboral a tus alumnos?" El cuestionario fue creado en la aplicación google formulario y en-viado de manera telemática. Los profesores cum-plimentaron el mismo de manera autónoma y on-line. Los resultados muestran que los profesores deTECO perciben de manera mayoritaria (92,5 %) una desconexión del vigente currículo LOGSE con las necesidades actuales de las empresas de turismo activo del contexto en el que se desarrolla la forma-ción. Es necesario un cambio en el currículo del TE-CO, que vincule la formación recibida con las nece-sidades del sector del turismo activo actuales.he curriculum of the medium vocational educa-tion course about leader of physical-sport activi-ties in the natural environment (TECO) is 20th years old (LOGSE system). The adventure tour-ism sector and the business context are develop-ment quickly (English, Funollet and Olivera, 2016). The objective of the present study is to know the teacher’s TECO perception about the adequacy of the current LOGSE curriculum ver-sus the business context of adventure tourism. The study is a non-experimental descriptive and sectional design, due to the characteristics of thesample composed of 50 TECO teachers of na-tional scope with whom it has been contacted. Data collection was making wiht ad hoc question-naire, which was validated by 10 expert judges (7 TECO professors and 3 university professors). Based on expert evaluations, a second question-naire was finally made with 6 main questions (and some sub-questions within them), such as "Do you think that the current LOGSE qualification is in line with what your work environment offers you for your students? "The questionnaire was created in the google form application and sent by telematic platform. The teachers completed the same autonomously and on-line. The results show that TECO teachers perceive majority (92.5%) a disconnection from the current LOGSE curriculum to the current needs of the adventure tourism companies in the context in which the training takes place. A change in the TECO curriculum is necessary, linking the training received with the needs of the current active tourism sector

Self-Optimization of Continuous Flow Electrochemical Synthesis Using Fourier Transform Infrared Spectroscopy and Gas Chromatography

A continuous-flow electrochemical synthesis platform has been developed to enable self-optimization of reaction conditions of organic electrochemical reactions using attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) and gas chromatography (GC) as online real-time monitoring techniques. We have overcome the challenges in using ATR FT-IR as the downstream analytical methods imposed when a large amount of hydrogen gas is produced from the counter electrode by designing two types of gas–liquid separators (GLS) for analysis of the product mixture flowing from the electrochemical reactor. In particular, we report an integrated GLS with an ATR FT-IR probe at the reactor outlet to give a facile and low-cost solution to determining the concentrations of products in gas–liquid two-phase flow. This approach provides a reliable method for quantifying low-volatile analytes, which can be problematic to be monitored by GC. Two electrochemical reactions the methoxylation of 1-formylpyrrolidine and the oxidation of 3-bromobenzyl alcohol were investigated to demonstrate that the optimal conditions can be located within the pre-defined multi-dimensional reaction parameter spaces without intervention of the operator by using the stable noisy optimization by branch and FIT (SNOBFIT) algorithm

Early Tracheostomy for Managing ICU Capacity During the COVID-19 Outbreak: A Propensity-Matched Cohort Study

10 p.Background: During the first wave of the COVID-19 pandemic, shortages of ventilators and ICU beds overwhelmed health care systems. Whether early tracheostomy reduces the duration of mechanical ventilation and ICU stay is controversial. Research question: Can failure-free day outcomes focused on ICU resources help to decide the optimal timing of tracheostomy in overburdened health care systems during viral epidemics? Study design and methods: This retrospective cohort study included consecutive patients with COVID-19 pneumonia who had undergone tracheostomy in 15 Spanish ICUs during the surge, when ICU occupancy modified clinician criteria to perform tracheostomy in Patients with COVID-19. We compared ventilator-free days at 28 and 60 days and ICU- and hospital bed-free days at 28 and 60 days in propensity score-matched cohorts who underwent tracheostomy at different timings (≤ 7 days, 8-10 days, and 11-14 days after intubation). Results: Of 1,939 patients admitted with COVID-19 pneumonia, 682 (35.2%) underwent tracheostomy, 382 (56%) within 14 days. Earlier tracheostomy was associated with more ventilator-free days at 28 days (≤ 7 days vs > 7 days [116 patients included in the analysis]: median, 9 days [interquartile range (IQR), 0-15 days] vs 3 days [IQR, 0-7 days]; difference between groups, 4.5 days; 95% CI, 2.3-6.7 days; 8-10 days vs > 10 days [222 patients analyzed]: 6 days [IQR, 0-10 days] vs 0 days [IQR, 0-6 days]; difference, 3.1 days; 95% CI, 1.7-4.5 days; 11-14 days vs > 14 days [318 patients analyzed]: 4 days [IQR, 0-9 days] vs 0 days [IQR, 0-2 days]; difference, 3 days; 95% CI, 2.1-3.9 days). Except hospital bed-free days at 28 days, all other end points were better with early tracheostomy. Interpretation: Optimal timing of tracheostomy may improve patient outcomes and may alleviate ICU capacity strain during the COVID-19 pandemic without increasing mortality. Tracheostomy within the first work on a ventilator in particular may improve ICU availability

Optimization of interneuron function by direct coupling of cell migration and axonal targeting

Neural circuit assembly relies on the precise synchronization of developmental processes, such as cell migration and axon targeting, but the cell-autonomous mechanisms coordinating these events remain largely unknown. Here we found that different classes of interneurons use distinct routes of migration to reach the embryonic cerebral cortex. Somatostatin-expressing interneurons that migrate through the marginal zone develop into Martinotti cells, one of the most distinctive classes of cortical interneurons. For these cells, migration through the marginal zone is linked to the development of their characteristic layer 1 axonal arborization. Altering the normal migratory route of Martinotti cells by conditional deletion of Mafb—a gene that is preferentially expressed by these cells—cell-autonomously disrupts axonal development and impairs the function of these cells in vivo. Our results suggest that migration and axon targeting programs are coupled to optimize the assembly of inhibitory circuits in the cerebral cortex