Design and analysis of a mechanical ventilation system based on cams

Low-cost mechanical ventilators have been developed in order to deal with the shortage of traditional ventilators whose quantity is not sufficient in an emergency context in Perú. Protofy, a company from Spain, designed one of the first low-cost mechanical ventilation systems OxyGEN which was approved by a medicine agency in its country in special context of COVID 19. Therefore, as main of this article, a redesign of this system named OxygenIP.PE was carried out according to local requirements and available technology, but maintaining its working concept based on compression mechanism by cams. Sensors were added and a control algorithm of the respiratory rate was developed. Ventilation curves monitoring over time was implemented; in this sense, a mathematical model of the whole system was developed. OxygenIP.PE was redesigned, fabricated, and tested measuring its ventilation curves over time. Results indicate that this redesign provides a sturdy equipment able to work during a longer lifetime than the original. The replicability of the ventilation curves behavior is ensured, while the mechanism dimensions are adapted for a particular airbag resuscitator. The mathematical model of the whole system can satisfactorily determine the ventilation curves over time and is used to show the air pressure, volume, and flow as a function of the compression arm's angular position and differential pressure through the breathing circuit measurement, furthermore the algorithms designed as a consequence of the mathematical model were implemented for Raspberry and ARDUINO microcontrollers. There were obtained parameters of pressure 10-65 cmH2O, airflow 50-65 l/m, volume 0-0.5 l, at two values of beat per minute (BPM) 15 and 25

Analysis of micro-properties for triaxial behaviour on coarse aggregates using DEM

This paper presents an analysis of the mechanical behaviour of coarse granular aggregates using the discrete element method. A background reference for the conducted study is the set of results of a few large scale triaxial tests performed at the UPC geotechnical laboratory. The basic tool used to simulate some of the tests is the computer code PFC3D. Rockfill particles (they have the size of gravels, typically ranging from 1 cm to 4 cm) were simulated as breakable clusters of 3D balls. Particle breakage occurs in time according to fracture mechanic’s laws. The relationship between stress intensity at a given particle, the size of an initial defect (crack) and the relative humidity could be established. This information was introduced in the numerical analysis to derive criteria for particle breakage in time. The paper describes the preliminary results of the work in progress. The influence of some properties such as particle shape, porosity, toughness, and friction coefficient was studied. The actual shape of rock gravels has been approximated by means of clusters of spherical particles. Several arrangements, comprising a different number of particles, have been tested, having always as reference validation criterion the results from triaxial tests performed. The results of the modelling exercise are encouraging and test results are reasonably well reproduced. The model is fairly general and it has a number of interesting capabilities

Reacciones químicas oscilantes: su historia

Se presenta un recuento histórico de los hechos más destacados, relacionados con el estudio de reacciones químicas oscilantes. Se ilustran y discuten algunos de los conceptos más importantes en el campo de estas reacciones

Simulación de mecanismos complejos de reacción.

Se propone un método para la interpretación de mecanismos complejos de reacción, el cual es aplicado a la simulación del mecanismo de Gyórgyi-Field, (GF) desarrollado para la reacción química oscilante de Belousov-Zhabotinsky (BZ). El método basado en la ley de acción de masas y en el principio de independencia y coexistencia de los pasos elementales, reproduce el comportamiento oscilatorio en la concentración de los intermediarios de reacción

Rigorous Multicomponent Reactive Separations Modelling : Complete Consideration of Reaction-Diffusion Phenomena

This paper gives the first step of the development of a rigorous multicomponent reactive separation model. Such a model is highly essential to further the optimization of acid gases removal plants (CO2 capture, gas treating, etc.) in terms of size and energy consumption, since chemical solvents are conventionally used.Firstly, two main modelling approaches are presented: the equilibrium-based and the rate-based approaches. Secondly, an extended rate-based model with rigorous modelling methodology for diffusion-reaction phenomena is proposed. The film theory and the generalized Maxwell-Stefan equations are used in order to characterize multicomponent interactions. The complete chain of chemical reactions is taken into account. The reactions can be kinetically controlled or at chemical equilibrium, and they are considered for both liquid film and liquid bulk. Thirdly, the method of numerical resolution is described. Coupling the generalized Maxwell-Stefan equations with chemical equilibrium equations leads to a highly non-linear Differential-Algebraic Equations system known as DAE index 3. The set of equations is discretized with finite-differences as its integration by Gear method is complex. The resulting algebraic system is resolved by the Newton- Raphson method. Finally, the present model and the associated methods of numerical resolution are validated for the example of esterification of methanol. This archetype non-electrolytic system permits an interesting analysis of reaction impact on mass transfer, especially near the phase interface. The numerical resolution of the model by Newton-Raphson method gives good results in terms of calculation time and convergence. The simulations show that the impact of reactions at chemical equilibrium and that of kinetically controlled reactions with high kinetics on mass transfer is relatively similar. Moreover, the Fick’s law is less adapted for multicomponent mixtures where some abnormalities such as counter-diffusion take place

Emergence of communities on a coevolutive model of wealth interchange

We present a model in which we investigate the structure and evolution of a random network that connects agents capable of exchanging wealth. Economic interactions between neighbors can occur only if the difference between their wealth is less than a threshold value that defines the width of the economic classes. If the interchange of wealth cannot be done, agents are reconnected with another randomly selected agent, allowing the network to evolve in time. On each interaction there is a probability of favoring the poorer agent, simulating the action of the government. We measure the Gini index, having real world values attached to reality. Besides the network structure showed a very close connection with the economic dynamic of the system.Comment: 5 pages, 7 figure

Síntomas músculo esqueléticos y percepción de calidad de vida en salud en trabajadores de una curtiembre.

The individual perception of quality of life in relation to health (QLH) may be related to physical disorders such as musculoskeletal disorders (MED), which may be a risk factor triggering diseases, creating economic impact due to absenteeism work. Objective: Establish the relationship between musculoskeletal symptoms (MSS) and perceived QLH among workers at a tannery. Methodology: Observational descriptive study in 56 workers in a tannery, Valle del Cauca. Two questionnaires were used in the date’s recollection: The Nordic to identify the presence of MSS and the SF-36 to assess the QLH. Potential associations between QLH dimensions and MSS were explored. Results: MSS most prevalent was pain in neck (60.7%), followed by back pain (58.9%) and wrist pain (48.2%). QLH dimensions more affected were Healt transition (53.6%), General Health (26.8%) and Body Pain (19.6%). A high risk workers relationated with Mental Health, the MED prevalence were Lumbar Pain (32,1%), Wrist Pain (26,8%) and Shoulder Pain (23,2%). A medium and high risk workers relationated with Physical Health were Lumbar Pain (23,2%), Neck Pain (19,6%) and Shoulder Pain (14,3%). Conclusion: According to the results the study establishes relationship between the presence of MSS and QLH.La percepción individual de calidad de vida en relación a la salud (CVS) puede estar relacionada con alteraciones físicas como desórdenes musculo esqueléticos (DME), lo cual puede convertirse en un factor de riesgo desencadenante de enfermedades profesionales, generando repercusiones económicas relacionadas con el ausentismo laboral. Objetivo: Establecer la relación entre los síntomas músculo esqueléticos (SME) y la percepción de CVS en los trabajadores de una Curtiembre. Metodología: Estudio observacional descriptivo en 56 trabajadores de una Curtiembre del Valle del Cauca. Para la recolección de datos se utilizaron los cuestionarios: Nórdico, que identifica presencia de SME; y el SF-36, que evalúa la CVS. Se exploró la relación de las dimensiones de calidad de vida y los SME. Resultados: El DME de mayor prevalencia fue Dolor a Nivel de Cuello (60,7%), seguido por Dolor Lumbar (58,9%) y Dolor en Muñecas (48,2%). Las dimensiones más afectadas de la CVS fueron: Transición en Salud (53,6%), Salud General (26,8%) y Dolor Corporal (19,6%). En los trabajadores con riesgo Alto en las esferas relacionadas con la Salud Mental, los SME de mayor prevalencia fueron de Dolor Lumbar (32,1%), Dolor en Muñecas (26,8%) y Dolor en Hombros (23,2%). Se presentó mayor prevalencia de Dolor Lumbar (23,2%), seguido de Dolor en Cuello (19,6%) y Dolor en Hombros (14,3%) en Riesgo Medio y Alto en las esferas relacionadas con la Salud Física. Conclusiones: Según estos resultados existe una relación entre los SME y la percepción de CVS

PÓRTICOS DE ENSAYO EN LABORATORIOS: UNIENDO LA TEORÍA Y LA PRÁCTICA MEDIANTE EL FORTALECIMIENTO DE LA INVESTIGACIÓN Y LA ACADEMIA

Los pórticos de ensayo de materiales se constituyen en una herramienta trascendental para la caracterización del comportamiento mecánico de elementos estructurales de variados materiales. La definición de relaciones fundamentales como la de esfuerzo-deformación, que permite diseñar estructuras de manera eficiente, adecuada y segura, deviene de extensas campañas experimentales. El uso de estos pórticos posibilita la investigación multidisciplinaria en las materias relacionadas con el estudio de materiales y también permite el estudio detallado de elementos estructurales fabricados con diferentes materiales, elementos de reuso que puedan provenir de procesos industriales como fibras naturales o residuos de vidrio. Los resultados obtenidos a partir de ensayos principalmente sobre vigas, permiten establecer la línea de investigación en materiales y elementos estructurales a partir del estudio de las relaciones esfuerzo-deformación para posibilitar la estimación de propiedades de elasticidad y de resistencia en materiales como acero, hormigón armado, muros, entre otros. El presente trabajo tiene el propósito de mostrar las facultades del empleo de pórticos de ensayos para disminuir la brecha entre la formación teórica y la aplicación práctica a nivel académico e investigativo dentro la ingeniería estructural y de materiales, a través de una revisión de la evolución y la utilidad de este tipo de elementos en la enseñanza. Con este fin, se desarrolla una revisión bibliográfica de trabajos desarrollados principalmente a nivel Latinoamericano en laboratorios que cuentan con pórticos de ensayos, se describe la evolución de estos elementos, las características principales de pórticos en el medio, las normativas asociadas al desarrollo de pruebas en estos equipos y finalmente se realiza un breve análisis de resultados experimentales y su relevancia en la academia y la investigación

Conjunto Mínimo Básico de Dados no Registo de Úlceras por Pressão (CMBD-UPP)

Para os profissionais de Enfermagem como para a totalidade das disciplinas em Ciências da Saúde, a necessidade de registar corretamente a sua atividade assistencial é um facto indispensável e obrigatório que, atualmente, ninguém discute. No entanto, o que se regista e a forma na que se faz, se é motivo desde tempo atrás de investigação para a sua melhora. (…) Se é importante interiorizar a necessidade de registar e parece evidente que estamos em sintonia, tão importante é conhecer quais são as variáveis que registamos e se é possível propor um consenso sobre aquelas que se considerem básicas e aquelas outras que ampliariam essa listagem imprescindível.info:eu-repo/semantics/publishedVersio

Estructura general de un software para captura y procesamiento de datos. aplicaciones a potenciometría y microcalorimetría de alta precisión

Se describe la estructura general de un programa desarrollado para la captura y procesamiento de datos calorimétricos y potenciométricos. Se destaca su utilidad a través del estudio de diferentes sistemas químicos como: evaluación de la entalpia de protonación del THAMHCI, seguimiento cuantitativo de la concentración del ion bromuro y del par redox Ce(III)/Ce(IV) durante el transcurso de la reacción química oscilante de Belousov-Zhabotinsky, y cuantificación de la entalpia de reacción con piridina de los sitios ácidos superficiales en una muestra de carbón estándar