Improving Optical Qualification of Solar Concentrator by FOCuS Tool

AbstractAn improved tool for the shape qualification of parabolic trough mirror modules used in concentrated solar power plants was developed. The tool is based on the fringe reflection theory, in which sinusoidal fringe patterns are projected on a screen and their reflection over a specular surface is recorded by a camera. The observed distortions in the image are related directly to surface deviations from ideal geometry. Relevant aspects of the technique are its high spatial resolution (more than 1 million points per facet), short measurement time and easy setup. The so called FOCuS tool is capable of calculating the mirror slope deviations from its ideal design and the RMS value as a quality factor. Furthermore, the tool generates a file which can be loaded on CENER'S TONATIUH ray tracing software, through a specially developed plug-in, for mirror modeling and intercept factor calculation with several tube absorber geometries

Caracterización térmica del reactor solar multitubular M&M

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolaRESUMEN: El objetivo de este trabajo es la caracterización térmica de un reactor solar de cavidad multitubular (M&M) bajo radiación solar concentrada del horno solar del Instituto de Energías Renovables de la UNAM (HoSIER); concebido para realizar reacciones termoquímicas de producción de combustibles limpios como son el hidrógeno y gas de síntesis. Ha habido diversas propuestas de reactores solares, pero no se ha estudiado de manera experimental los efectos que tiene la distribución geométrica de los tubos dentro de la cavidad en su comportamiento térmico, en la inercia térmica ante los cambios de la irradiancia solar y con el flujo de aire dentro de los mismos. La caracterización se realizó en función del arreglo de los tubos en la cavidad, la estabilidad y homogeneidad de la temperatura entre los tubos y la evaluación de la inercia térmica del reactor en función de las variaciones de la irradiancia solar. Los resultados muestran que el arreglo propuesto tiene una buena estabilidad térmica y puede responder fácilmente ante cambios súbitos en la irradiancia solar. La diferencia mínima de temperatura alcanzada entre los tubos fue de 72ºC cuando la temperatura del tubo central fue de 1200ºC, equivalente a 6% de diferencia.ABSTRACT: The main objective of this work is the thermal characterization of a multi-tubular cavity solar reactor (M&M) under concentrated solar radiation from the solar furnace of the Renewable Energy Institute of the UNAM (HoSIER); conceived to perform thermochemical reactions to produce clean fuels as the hydrogen and synthesis gas. There have been various proposals for solar reactors, but the effects of the geometric distribution of the tubes within the cavity on their thermal behavior, on thermal inertia with changes in solar irradiance and air flux inside them, have not been experimentally studied. The characterization was performed as a function of the tubes arrangements, the stability and the temperature homogeneity between tubes, and the thermal inertia evaluation as a function of solar irradiance. The results show that the proposed arrangement has good thermal stability and can easily respond to sudden changes in solar irradiance. The minimum temperature difference reached between the tubes was 72ºC, when the central tube reaches 1200ºC, equivalent to 6% difference.info:eu-repo/semantics/publishedVersio

Shock Wave Structure in a Strongly Nonlinear Granular Lattice with Viscous Dissipation

The shock wave structure in a one-dimensional lattice (e.g. granular chain) with a power law dependence of force on displacement between particles with viscous dissipation is considered and compared to the corresponding long wave approximation. A dissipative term depending on the relative velocity between neighboring particles is included in the discrete model to investigate its influence on the shape of steady shock profiles. The critical viscosity coefficient is obtained from the long-wave approximation for arbitrary values of the exponent n and denotes the transition from an oscillatory to a monotonic shock profile in stronly nonlinear systems. The expression for the critical viscosity coefficient converges to the known equation for the critical viscosity in the weakly nonlinear case. Values of viscosity based on this expression are comparable to the values obtained in the numerical analysis of a discrete particle lattice with a Herzian contact interaction corresponding to n = 3/2. An initial disturbance in a discrete system approaches a stationary shock profile after traveling a short distance that is comparable to the width of the leading pulse of a stationary shock front. The shock front width is minimized when the viscosity is equal to its critical value.Comment: 20 pages, 6 figure

Tunability of solitary wave properties in one dimensional strongly nonlinear phononic crystals

One dimentional strongly nonlinear phononic crystals were assembled from chains of PTFE (polytetrafluoroethylene) and stainless steel spheres with gauges installed inside the beads. Trains of strongly nonlinear solitary waves were excited by an impact. A significant modification of the signal shape and an increase of solitary wave speed up to two times (at the same amplitude of dynamic contact force)were achieved through a noncontact magnetically induced precompression of the chains. Data for PTFE based chains are presented for the first time and data for stainless steel based chains were extended into a smaller range of amplitudes by more than one order of magnitude than previously reported. Experimental results were found to be in reasonable agreement with the long wave approximation and with numerical calculations based on Hertz interaction law for discrete chains.Comment: 36 pages, 7 figure

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Las energías renovables: la energía solar y sus aplicaciones*

Tema del mesEl objetivo de este trabajo es reflexionar sobre el problema actual de la energía en el mundo y en México y considerar a las energías renovables (ER), en particular a la solar como una alternativa para enfrentar el agotamiento de los yacimientos de combustibles fósiles y garantizar la conservación del medio ambiente permitiendo acceder a un desarrollo sustentable. En el artículo se plantea el problema de la energía en el mundo y en México, los mercados de las ER, la estructura energética mundial y en México, las inversiones en ciencia y tecnología en ER, los escenarios futuros de la energía y las tecnologías de energía solar y sus aplicacione