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Indoor air conditioning is currently a topic of much interest, not only to save energy but also due to public health issues such as pandemics. This study focuses on the thermal comfort and air quality of a closed, air-conditioned space located in an extremely hot climate. Due to noise and weather conditions, the door and window of the space are kept closed at all times. The study uses computational fluid dynamics techniques and the finite element method. Average temperatures and CO2 concentrations, as well as effectiveness for temperature and concentration distribution, are calculated for the analysis. Results indicate that supplying air away from hot walls improves air quality and thermal comfort. Furthermore, there is an optimal Reynolds number that depends on the number of people inside the space. Due to the above, it is possible to find an ideal configuration that simultaneously allows for efficient energy use, helps to avoid the adverse effects of CO2 on daily activities such as working or studying, and supports people’s health and comfort.

The aim of this work is the simulation of volumetric strain of tuberous crop during drying. We propose a poroelastic model for predicting the drying kinetics and volume loss of potato cubes during convective drying. The Biot’s theory of poroelasticity was used, which considers the Lamé parameters, Young’s modulus and Poisson’s ratio. Drying kinetics and volumetric strain were modeled and compared versus experimental data. An X-ray microtomograph coupled with image analysis was used to visualize the shape and size of the samples during drying. Drying experiments were conducted at 50, 60 and 70 °C, 20% RH, with an air velocity of 1 and 2 m/s. The drying process was interrupted several times to perform tomographic acquisitions. We found a period of ideal shrinkage, nevertheless, the volumetric strain reveals a kinetic behavior over time. The model computes the volumetric strain, which describes correctly the experimental data obtained by microtomography.

Due to the current COVID-19 pandemic, guaranteeing thermal comfort and low CO

A reduced set of reaction kinetic mechanism was obtained for the combustion of n-butanol in air, including low temperature ignition phenomena. Fourteen chemical-kinetic reactions are identified, and their associated reaction-rate parameters are given and added to an existing short chemical-kinetic mechanism (the San Diego mechanism); this entails introducing six new additional chemical species. Two important features of the reaction of the hydroxybutyl radical C4H8OH-1 radical with molecular oxygen involve a path competition of low and high temperature reactions, and low total available heat release not promoting NTC behavior. Tests of predictions against measured ignition delay times and laminar burning velocities are reported and compared with recent measurements in jet-stirred reactors. The comparisons support the predictions of the mechanism, which may be useful in combustion computations, especially when larger mechanisms would be too time-consuming to be accommodated.

En el presente trabajo, se propone un modelo matemático capaz de predecir la deformación en cilindros de papa (Solanum tuberosum) sometidos a un proceso de secado convectivo a temperaturas de 40, 50 y 60 ºC, con humedad relativa y velocidad de aire constantes. El modelo considera la consrvación de masa y calor acoplada a un modelo de mecánica de sólidos basado en la teoría poroelástica de Biot. El acoplamiento considera los cambios de presión causados por la migración de agua líquida y las deformaciones sufridas por el material como consecuencia de los cambios de tensión en la interacción fluido-sólido. Para el cómputo de la presión de vapor en el material se incluyeron las isotermas de desorción del tubérculo. Para el modelo poroelástico fueron considerados parámetros mecánicos del material, tales como los parámetros de Lamé, los módulos de Young y Poisson, además de una ecuación de conservación de Darcy para involucrar las presiones que ejerce la fase líquida en la matriz sólida.

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.

Abdominal pregnancy is uncommon and associated with higher fetal and maternal mortality. It is rare to grow to term and furthermore obtain a newborn in good conditions. A case of abdominal pregnancy at term ( 40,5 weeks) which was successfully treated in the Clinica General del Norte, Barranquilla, Colombia, by the obstetrics and gynecologist department; was an obstetric patient of 33 years old, G2P1 with initial diagnosis of 40,5 weeks of gestation, abruptio placentae and pre-eclampsia; with postoperative diagnosis of abdominal pregnancy at term with a newborn in good conditions. This article is a case report. It has a general interest for two reasons: 1) Its an uncommon event in obstetrics, the abdominal pregnancies with an alive fetus have very now frequency in the world. 2) A brief revision and how to confront this kind of cases is made.

In the present paper, an electronic prototype designed to acquire electrocardiographic signals from marine mammals has been developed. The system consists of a portable device that allows the on-line acquisition of EKG signals through a parallel port interface that is connected to a laptop computer. The EKG waveform, the voltage level, the bandwidth and the most relevant information from this type of signals is stored and analysed under real-time conditions by means of specifically implemented software. The whole system has been successfully tested to obtain the EKG from captive dolphins. The characteristics of the equipment presented here, with its low cost, size and energy requirements accomplish a portable system suitable for the acquisition of this type of signals in conductive media such as the seawater.

A simple and low-cost acquisition device using the computer parallel port has been used to implement a full acquisition system composed of an analogue interface, a 12-bit analogue-to-digital converter, a quad three to one multiplexer and a software package aimed at managing the acquisition process. The features of this system make its implementation a suitable educational resource for undergraduate students from Engineering, Physics and Computer Sciences faculties.