Computational Study of Thermal Comfort and Reduction of CO2 Levels inside a Classroom.

Due to the current COVID-19 pandemic, guaranteeing thermal comfort and low CO2 levels in classrooms through efficient ventilation has become vitally important. This study presents three-dimensional simulations based on computational fluid dynamics of airflow inside an air-conditioned classroom located in Veracruz, Mexico. The analysis included various positions of an air extractor, Reynolds numbers up to 3.5 × 104, four different concentrations of pollutant sources, and three different times of the day. The simulations produced velocity, air temperature, and CO2 concentrations fields, and we calculated average air temperatures, average CO2 concentrations, and overall ventilation effectiveness. Our results revealed an optimal extractor position and Reynolds number conducive to thermal comfort and low CO2 levels due to an adequate ventilation configuration. At high pollutant concentrations, it is necessary to reduce the number of students in the classroom to achieve safe CO2 levels.

Numerical Study of Nanofluid Irreversibilities in a Heat Exchanger Used with an Aqueous Medium.

Heat exchangers play an important role in different industrial processes; therefore, it is important to characterize these devices to improve their efficiency by guaranteeing the efficient use of energy. In this study, we carry out a numerical analysis of flow dynamics, heat transfer, and entropy generation inside a heat exchanger; an aqueous medium used for oil extraction flows through the exchanger. Hot water flows on the shell side; nanoparticles have been added to the water in order to improve heat transfer toward the cold aqueous medium flowing on the tube side. The aqueous medium must reach a certain temperature in order to obtain its oil extraction properties. The analysis is performed for different Richardson numbers (Ri = 0.1-10), nanofluid volume fractions (φ = 0.00-0.06), and heat exchanger heights (H = 0.6-1.0). Results are presented in terms of Nusselt number, total entropy generation, Bejan number, and performance evaluation criterion. Results showed that heat exchanger performance increases with the increase in Ri when Ri > 1 and when reducing H.

Application of the Max-Lloyd quantizer for ECG compression in diving mammals.

This article presents a practical implementation of an ECG compression algorithm using a Max-Lloyd quantizer, to optimize the low resources of an ECG acquisition and transmission system (telemetry system) for dolphins and human divers. The algorithm scheme is based on a first-order differential pulse code modulation (DPCM) and uses a Max-Lloyd quantizer to code the difference between the current and predicted samples. The use of the non-uniform quantizer instead of a uniform quantizer improves the percent root mean-square difference (PRD), thereby producing a low distortion in the reconstructed signals. Due to its low computational complexity, the compression process can be accomplished on-line during the ECG acquisition process.

Embarazo abdominal a término: report de un caso / Abdominal pregnancy a term: case report

El embarazo abdominal es poco frecuente y está asociado con alta mortalidad materna y fetal. Es raro que llegue al término y mucho más obtener un recién nacido en buenas condiciones. Un caso de embarazo abdominal a término (40,5 semanas), el cual fue atendido exitosamente en la Clínica General del Norte en Barranquilla, Colombia por el Departamento de Ginecología y Obstetricia: Paciente de 33 años G2P1 con diagnóstico de ingreso de embarazo de 40,5 semanas, DPPNI y pre-eclampsia; a quien se le hizo un diagnóstico transoperatorio de embarazo abdominal a término, con producto de la gestación eb buenas condiciones.