Inclusion of Mechanical Dampers in the Multimodal Flutter Analysis of Slender Structures

[Abstract] Sometimes slender structures are reinforced with mechanical dampers to reduce the vibrations caused by aeroelastic phenomena like flutter. However the formulation of flutter analysis only considers the classical damping ratio to take into account the structural damping. This paper explains the procedure used for adding mechanical dampers with a known constant to the analysis software FLAS. This code was developed at Universidade da Coruña to calculate the critical wind speed for flutter instability. An example of a solar tracker with two rows of flat panels is shown. In this slender structure two mechanical dampers are used to reduce the vibrations caused by the wind in structure interaction. The solar tracker has been studied for five different positions of the angle of attack. Results of flutter speed for several values of the dampers constant and global structural damping ratio are presented.This work has been funded by the Spanish Minister of Science and Innovation with reference PID2019-110786GB-I00 and the Galician regional government with reference ED431C2017/72. The collaboration in the wind tunnel test of the Research Assistant Miguel Roca is recognizedXunta de Galicia; ED431C2017/7

Characterization of patients diagnosed with vulvar lichen sclerosus

Introducción: el liquen escleroso vulvar es una dermatosis inflamatoria crónica y progresiva, infradiagnosticada y subtratada, con tendencia a la malignización. El diagnóstico oportuno y tratamiento precoz son fundamentales.Objetivo: caracterizar las pacientes con diagnóstico de liquen escleroso vulvar.  Métodos: se realizó un estudio observacional, descriptivo, transversal, de serie de casos. La muestra coincide con el universo por lo que el muestreo fue no probabilístico de tipo intencional. Se incluyeron las mujeres con liquen escleroso vulvar, atendidas en el municipio Chambas desde enero de 2015 hasta septiembre de 2022, se excluyeron las pacientes con historias clínicas incompletas. Como medida de resumen de la información se utilizaron frecuencias absolutas y relativas (porcentaje).Resultados: existió predominio del grupo de edades 60 – 69 años (66,7 %) y color de piel blanca (71,4 %). El 52,4 % perteneció al área Julio Castillo. La media de edad fue de 64,8±6,217 años. El prurito vulvar e hipopigmentación estuvieron presentes en el 100 % de las pacientes. El 61,9 % de las mujeres desarrollaron una neoplasia vulvar intraepitelial diferenciada. En el 48,2 % de los casos el tiempo de evolución fue mayor de tres años. Recibieron tratamiento quirúrgico el 71,4 %.Conclusiones: la enfermedad predominó en la tercera edad; la hipopigmentación y el prurito vulvar fueron una constante en las pacientes estudiadas, la mayoría desarrolló una neoplasia intraepitelial vulvar diferenciada con más de tres años de evolución de las lesiones y el tratamiento quirúrgico fue la conducta más aplicada.Introduction: Vulvar lichen sclerosus is a chronic and progressive inflammatory dermatosis, underdiagnosed and undertreated, with a tendency to malignancy. Timely diagnosis and early treatment are essential.Objective: To characterize patients with a diagnosis of vulvar lichen sclerosus attended in the health areas of Chambas municipality, Ciego de Avila.Methods: An observational, descriptive, cross-sectional, case series study was conducted. The sample coincides with the universe so the sampling was intentional non-probabilistic. Women with vulvar lichen sclerosus, treated in Chambas municipality from January 2015 to September 2022, were included, patients with incomplete medical histories were excluded. Absolute and relative frequencies (percentage) were used as a summary measure.Results: There was a predominance of the age group 60-69 years (66,7 %) and white skin color (71,4 %). 52,4 % belonged to the white group. The 52,4 % belonged to the Julio Castillo area. The mean age was 64,8±6,217 years. Vulvar pruritus and hypopigmentation were present in 100 % of the patients. Differentiated vulvar intraepithelial neoplasia developed in 61,9 % of the women. In 48,2 % of the cases the time of evolution was longer than three years. They received surgical treatment 71,4 %.Conclusions: The disease predominated in the elderly; Hypopigmentation and vulvar pruritus were a constant in the patients studied, most developed a differentiated vulvar intraepithelial neoplasia with more than three years of evolution of the lesions and surgical treatment was the most applied behavior

Comparación de dos técnicas de sutura para cierre aponeurótico en laparotomía media en pacientes con alto riesgo de evisceración posquirúrgica

ResumenIntroducciónLa evisceración posquirúrgica es una complicación con origen multifactorial. Los estudios para prevenirla modifican la técnica de cierre. La técnica reinforced tensión line (RTL) se ha usado en el tratamiento de hernias incisionales.Material y métodosEnsayo clínico en pacientes sometidos a laparotomía media. Se formaron dos grupos: 1) control con cierre habitual, y 2) grupo experimental con la técnica RTL. Se evaluó la presencia de evisceración posquirúrgica.ResultadosTerminaron el estudio 89 pacientes. Se presentaron un total de 9 (20%) y 2 (4.5%) evisceraciones, con diferencia a favor de la técnica RTL con una p de 0.0273.ConclusionesSe encontró que la técnica RTL reduce la incidencia de evisceración posquirúrgica.AbstractBackgroundPostsurgical evisceration is a complication, its origin is multifactorial. There are reports in the literature to prevent changing the closing technique. Reinforced tension line technique (RTL) has proven useful in the treatment of incisional hernias.Material and methodsClinical trial in patients undergoing midline laparotomy first time, two groups were formed the control group was sutured with the principles of Jenkins and the experimental group with RTL technique. The presence of postoperative evisceration between the two groups and associated complications were evaluated.ResultsCompleted the study 89, a total of 9 (20%) evisceration in the control group and 2 (4.5%) occurred in the study group, with statistical significance in favor of the RTL technique with p 0.0273.ConclusionIt was found that the RTL technique reduces the incidence of postoperative evisceratio

Plan de negocio para la fabricación y comercialización de dispensadores de Toallas Femeninas en baños de establecimientos de la ciudad de Managua

La investigación presenta un plan de negocio está orientado a la creación e introducción de un nuevo producto al mercado, con un nuevo concepto en complementos de servicios higiénicos para damas, para la elaboración de dicho producto se ha propuesto un diseño y se han establecido los procesos que permitan su fabricación e incorporación al mercado a través de la institución de una empresa encargada de la fabricación y distribución de dicho ´producto, que está definido como dispensador de toallas femeninas

Resistance and inactivation kinetics of bacterial strains isolated from the Non-chlorinated and chlorinated effluents of a WWTP

The microbiological quality of water from a wastewater treatment plant that uses sodium hypochlorite as a disinfectant was assessed. Mesophilic aerobic bacteria were not removed efficiently. This fact allowed for the isolation of several bacterial strains from the effluents. Molecular identification indicated that the strains were related to Aeromonas hydrophila, Escherichia coli (three strains), Enterobacter cloacae, Kluyvera cryocrescens (three strains), Kluyvera intermedia, Citrobacter freundii (two strains), Bacillus sp. and Enterobacter sp. The first five strains, which were isolated from the non-chlorinated effluent, were used to test resistance to chlorine disinfection using three sets of variables: disinfectant concentration (8, 20 and 30 mg·L−1), contact time (0, 15 and 30 min) and water temperature (20, 25 and 30 °C). The results demonstrated that the strains have independent responses to experimental conditions and that the most efficient treatment was an 8 mg·L−1 dose of disinfectant at a temperature of 20 °C for 30 min. The other eight strains, which were isolated from the chlorinated effluent, were used to analyze inactivation kinetics using the disinfectant at a dose of 15 mg·L−1 with various retention times (0, 10, 20, 30, 60 and 90 min). The results indicated that during the inactivation process, there was no relationship between removal percentage and retention time and that the strains have no common response to the treatmentsThe work of SM-H was supported by a graduate scholarship (number 217745) that was kindly provided by CONACyT, Mexico. Some chemical reagents were generously provided by the Administration of the B.A. in Biology at UAEH, Mexico. We thank the Instituto Tecnológico de Estudios Superiores de Monterrey, Hidalgo campus, for allowing us to sample from its WWTP. The authors recognize Jose A. Rodriguez-Ávila for his comments on the procedure for analyzing inactivation kineticsS

Distribución espacial de la evapotranspiración del cultivo de referencia y de la precipitación efectiva para las provincias del centro-noreste de Argentina

This paper falls within the framework of the FAO-INA Agreement that was entered into to "identify new potential irrigated and supplementary-irrigated areas in the basins of northeastern Argentina". The agreement seeks to collect information on monthly reference crop evapotranspiration (ETo), analyze its variability, and show it on isoline maps. The study comprised the central northeastern part of Argentina; the program used was CROPWAT 8.0 – FAO; and climate data were obtained from CLIMWAT 2.0. The information was plotted with ArcView 3.2ª and the variables of interest wereinterpolated with the Kriging method. Results show that: a) Santiago del Estero is the station with the highest annual ETo: 1767 mm.year-1, while the lowest ETo value is found in Loreto (Misiones) with 1150 mm.year-1; b) the average ETo in January ranges between 160 to 200 mm.month-1, while in July it is between 35 - 90 mm.month-1; c) the average ETo in January in the northeastern part of Cordoba ranges between 165 - 185 mm. month-1 while in July the variability is less pronounced; and d) rainfall in an average hydrological year ranges between 605 and 1825 mm.year-1 with an effective rainfall of 500 and 1400 mm.year-1 that tends to increase towards the northeast.Este trabajo se enmarca en el Acuerdo FAO-INA (Instituto Nacional del Agua) "Identificación de potenciales nuevas áreas de regadío y áreas de riego complementario en las cuencas de la zona nordeste de Argentina". Sus objetivos: conocer la evapotranspiración mensual del cultivo de referencia (ETo), analizar su variabilidad y representarla espacialmente. El estudio comprendió el centro-noreste de Argentina, utilizó el programa CROPWAT 8.0 - FAO y los datos climáticos fueron obtenidos de la base CLIMWAT 2.0. La información se volcó en formato gráfico utilizando Arc View 3.2ª y las variables de interés se interpolaron mediante el método Kriging. Los resultados muestran: (a) la estación con mayor ETo anual es Santiago del Estero: 1767 mm.año-1; la mínima ETo (1150 mm.año-1) se observa en Loreto (Misiones), (b) la ETo media del área de estudio para enero varía entre 160 y 200 mm.mes-1 y la de julio está comprendida entre 35 y 90 mm.mes-1, (c) en el NE de Córdoba la ETo media de enero varía entre 165 y 185 mm.mes-1, mientras que en julio, la variabilidad es menor y (d) la lluvia para un año hidrológico medio varía entre 605 y 1825 mm.año-1 con una precipitación efectiva comprendida entre 500 y 1400 mm.año-1 aumentando hacia el noreste

Wind tunnel study on the effect of the gap width in the aerodynamic and aeroelastic responses of twin-box decks

Advances in Fluid Mechanics XII (WIT Transactions on Engineering Sciences; v.120). Containing papers from the 12th International Conference on Advances in Fluid Mechanics, this book covers a wide range of topics including basic formulations and their computer modelling as well as the relationship between experimental and analytical results. The emphasis is on new applications and research currently in progress.[Abstract:] Twin-box decks have recently been introduced in long-span bridges because this type of slotted cross-section provides flutter critical wind speeds higher than mono-box streamlined decks for flexible structures. The two parallel girders are linked together by means of transverse beams with a central gap between them. Experimental and CFD studies have shown that the length of this central gap plays a key role in the aerodynamic and aeroelastic responses of the deck. In this work, the geometry of the Stonecutters Bridge in Hong Kong (China) has been chosen as an application case to conduct a series of parametric studies based on wind tunnel tests. The tests have been conducted under smooth flow, for a 1:80 geometric scale sectional model able to modify its slot length. For an ample range of gap lengths, the force coefficients and the flutter derivatives have been obtained. It has been found that the slopes of the lift and moment coefficients suffer important changes with the gap length. In the same manner, it has also been found that the gap distance modifies the values of flutter derivatives. Finally, for a long-span bridge example, the critical flutter speeds for different gaps are obtained, aiming to identify the gap length that provides a safer threshold for the flutter phenomenon. The results reported herein permit the assessment of the impact caused by the gap length in the aerodynamic and aeroelastic responses of twin-box decks.The research leading to these results has been funded by the Spanish Minister of Economy, Industry and Competitiveness (MINECO) with project reference BIA2016-76656-R, and the Galician regional government with reference ED431C2017/72. A.J. Álvarez has been funded by the Spanish Ministry of Economy and Competitiveness in the frame of the National Program for Promotion of Talent and Employability through the BES-2014-068418 predoctoral contract grant, associated with the BIA2013-41965-P research project.Xunta de Galicia; ED431C2017/7

Effects of gamma-Ray radiation on magnetic properties of NdFeB and SmCo permanent magnets for space applications

Several samples of NdFeB and SmCo permanent magnets have been irradiated with gamma rays up to different total irradiation doses until 1Mrad(Si). Magnetic properties of the samples have been measured at different temperatures before and after irradiation. The modifications of the magnetic parameters are presented. From these results it is highlighted which permanent magnets show more resistance to radiation and are more suitable to be included in devices for space applications or high radiation environments

Trypanosoma cruzi: Seroprevalence Detection in Suburban Population of Santiago de Querétaro (Mexico)

Objectives. To evaluate the potential of iron-oxide dismutase excreted (SODeCRU) by T. cruzi as the antigen fraction in the serodiagnosis of Chagas disease and compile new epidemiological data on the seroprevalence of this disease in the suburban population of the city of Santiago de Querétaro (Mexico). Design and Methods. 258 human sera were analyzed by the techniques of ELISA and Western blot and using the homogenate and the SODeCRU. Results. A total of 31 sera were positive against ELISA/SODeCRU (12.4%), while 30 sera proved positive by WB/SODeCRU (11.6%). The comparison between the technique of ELISA and WB showed a sensitivity of 93%, and a specificity of 99%. The positive predictive value was 93% and the negative predictive value was 99%, with a Kappa (κ) value of 1. Conclusions. These preliminary data reveal the degree of infection of nonrural areas of Mexico and demonstrated that SODeCRU is an antigen useful to diagnose Chagas disease