Computational buckling analysis of cylindrical panels under uniform pressure

En este trabajo se investiga una metodología de energía reducida para calcular el límite inferior de carga de pandeo de paneles cilíndricos rebajados. La formulación de esta nueva metodología está basada en los postulados establecidos en la literatura para el cálculo de límites inferiores de carga de pandeo y se ha implementado en un programa de elementos finitos de aplicaciones múltiples. Se han analizado paneles formados de material isotrópico y caracterizados por tres valores del parámetro de Batdorf. De la comparación de los resultados obtenidos con la metodología propuesta con aquellos obtenidos de análisis no lineales incluyendo diferentes niveles de imperfección geométrica, surge que el modelo de energía reducida aplicado a paneles cilíndricos no conduce a límites inferiores de carga de pandeo. Si bien este nuevo modelo de energía reducida predice cargas de pandeo inferiores a las obtenidas del análisis clásico, éstas son mayores que las obtenidas de análisis no lineales. Sin embargo, la viabilidad de la implementación de una metodología de energía reducida en un programa de elementos finitos de aplicaciones múltiples queda demostrada.Peer Reviewe

Development of Surrogate Hand for Impact Tests

Despite continuous advancements in technology and safety procedures, hand injuries are still a significant problem in many industries. Metacarpal gloves are often used by workers to protect their hands against impacts, cuts, and other hazards. Importantly, testing the level of impact protection offered by different designs of metacarpal gloves cannot be done with living subjects. This limitation requires the use of a surrogate hand which can be used consistently and systematically in controlled impact tests. This work focuses on the development of a surrogate hand which can be manufactured and used for this purpose. The surrogate hand developed in this work is comprised of a bone structure and a flexible synthetic gel material, and the hand design is based on digital models obtained through laser scanning of bone and hand shapes. These digital models were scaled and assembled using a mesh editing software to generate a representative hand with the required size and posture. The resulting hand model was materialized with a 3D-printed bone structure surrounded by synthetic gel with shape, proportions, and flexibility resembling that of an actual hand

Testing of full-scale confined inflatable for the protection of tunnels

There are approximately 337 highway tunnels and 211 rail transit tunnels in the United States; many of these tunnels are beneath bodies of water.1 Every day, more than 11.3 million passengers in 35 metropolitan areas and 22 states use some form of rail transit, either commuter, heavy, or light rail.2 It is well known that man-made or natural disasters can significantly disrupt the functionality of critical transportation infrastructure. Some examples in the United States include the 1992 Chicago freight tunnel flood;3 the 2003 flooding of the Midtown Tunnel in Virginia caused by Hurricane Isabel;4 and the 2012 flooding of New York City, when Hurricane Sandy caused seven subway tunnels under the East River to flood and remain inoperable for several days.5 Tunnel safety and integrity is a subject of special concern, not only because tunnels are of difficult and limited accessibility, but also because most of the potential threats (e.g. fires, flooding, or noxious substances) compromise the integrity of entire connecting system as the threat can spread along it.6Conventional emergency sealing systems are not always installed or operational during the occurrence of extraordinary events, prompting the evaluation of alternative solutions, such as inflatable plugs.7-10 An inflatable plug can seal off and protect an underground system by stopping hazards, such as smoke or flooding. Unlike floodgates, an inflatable plug is fast-deploying, relatively inexpensive, and can be quickly installed in a small space in an existing tunnel or conduit. The concept was demonstrated in 2008 in the Washington D.C. Metro system with promising results.7, 9 This work describes additional full scale testing performed between late 2011 and 2012 for the development of confined inflatable structures for the protection of tunnels completed at West Virginia University

Large-scale inflatable structures for tunnel protection: a review of the Resilient Tunnel Plug project

The protection of underground civil infrastructure continues to be a high priority for transportation and transit security agencies. In particular, rail transit tunnels running under bodies of water are susceptible to disruptions due to flooding caused by extraordinary climatic events such as hurricanes or other events resulting from human activities. Several events have taken place in the past decades that have demonstrated the need to mitigate vulnerabilities or, at least, minimize the consequences of catastrophic events. Although it is impossible to prevent all situations that can lead to flooding, damage can be substantially decreased by reducing the area affected by the event. To minimize the effects of an event, a possible approach is to compartmentalize the tunnel system by creating temporary barriers that can contain the propagation of flooding until a more permanent solution can be implemented. One way to create a temporary barrier is by the deployment of a large-scale inflatable structure, also known as an inflatable plug. In such an application, the inflatable structure is prepared for placement, either permanently or temporally, and maintained ready for deployment, inflation, and pressurization when needed. The internal plug pressure imparts a normal force against the tunnel wall surface with the friction between the plug and tunnel surfaces opposing axial movement of the plug. The sealing effectiveness depends on the ability of the inflatable structure to self-deploy and fit, without human intervention, to the intricacies of the perimeter of the conduit being sealed. Primary design constraints include having the plug stowed away from the dynamic envelope of the trains and being able to withhold the pressure of the flooding water. This work presents a compilation of the main aspects of the activities completed for the development of large-scale inflatable structures as part of the Resilient Tunnel Plug (RTP) Project. The main test results and lessons learned are presented to demonstrate the viability of implementing large-scale inflatable plugs for the containment of flooding in rail tunnels systems. Over 400 coupon and specimen tests, 200 reduced scale tests, and 100 full-scale tests were conducted to demonstrate the efficacy of the design of different prototypes over a 10-year research and development project. The culmination of the work was 12 large-scale flooding demonstrations where the inflatable tunnel plug was shown able to be deployed remotely and withstand a simulated flooding event

Friction and leakage characteristics of confined, reduced-scale inflatable structures

This work is focused on the evaluation of the performance of a small-scale inflatable, or plug, placed in a confined space provided by a circular rigid pipe as a way to contain the propagation of floods. The rigid pipe is a simplified and scaled approximation of an actual tunnel section. The evaluations were conducted using an inflatable plug made of a single layer of coated Vectran® fabric. Friction coefficients of the system were calculated for three different materials lining the pipe so a comparison could be made. These friction coefficients were also compared to laboratory friction machine testing of the same lining materials. This comparison showed that the friction coefficients of the pipe-plug system were lower than the laboratory friction machine tests. Rates of water leakage around the plug were also studied. The leakage rates were recorded for several different plug pressures while varying the tunnel pressure accordingly. It was observed that as pressure differential decreased between the plug and pipe, the leakage rate increased. Results showed also that the plug was able to withstand a pressure differential with manageable water leakage rates

First results of the glitching pulsars monitoring program at the Argentine Institute of Radioastronomy

We report here on the first results of a systematic monitoring of southern glitching pulsars at the Argentine Institute of Radio astronomy started on the year 2019. We detected a major glitch in the Vela pulsar (PSR J0835$-$4510) and two mini-glitches in PSR J1048$-$5832. For each glitch, we present the measurement of glitch parameters by fitting timing residuals. We then make an individual pulses study of Vela in observations previous and after the glitch. We selected 6 days of observations around the major glitch on July 22nd 2021 and study their statistical properties with machine learning techniques. We use Variational AutoEncoder (VAE) reconstruction of the pulses to separate them clearly from the noise. We perform a study with Self-Organizing Maps (SOM) clustering techniques and find an unusual behavior of the clusters two days prior to the glitch. This behavior is only visible in the the higher amplitude pulse clusters and if intrinsic to the pulsar could be interpreted as a precursor of the glitch.Comment: 13 pages, 13 figures, 13 table

Localización geográfica de ganado utilizando modelos de propagación de señal y XBee

En este artículo se presentan los avances en una línea de investigación y desarrollo enfocada en la experimentación con aplicaciones de Redes de Sensores Inalámbricos para soportar servicios en un contexto de Ambientes Inteligentes. El objetivo de la línea, radica en el diseño e implantación de un prototipo harware/software basado en Redes de Sensores Inalámbricos (Wireless Sensor Networks WSN) para capturar la intensidad de las señales de los enrutadores móviles, y mediante el método de Trilateración, ayudar a la localización de ganado en un área determinada. El prototipo permite analizar distintos modelos de propagación y técnicas de estimación de distancia y visualizar los resultados en una interfaz web amigable. El prototipo está en su fase de prueba en laboratorio y de obtención de los primeros resultados en campo.Eje: Arquitectura, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI

Localización geográfica de ganado utilizando modelos de propagación de señal y XBee

En este artículo se presentan los avances en una línea de investigación y desarrollo enfocada en la experimentación con aplicaciones de Redes de Sensores Inalámbricos para soportar servicios en un contexto de Ambientes Inteligentes. El objetivo de la línea, radica en el diseño e implantación de un prototipo harware/software basado en Redes de Sensores Inalámbricos (Wireless Sensor Networks WSN) para capturar la intensidad de las señales de los enrutadores móviles, y mediante el método de Trilateración, ayudar a la localización de ganado en un área determinada. El prototipo permite analizar distintos modelos de propagación y técnicas de estimación de distancia y visualizar los resultados en una interfaz web amigable. El prototipo está en su fase de prueba en laboratorio y de obtención de los primeros resultados en campo.Eje: Arquitectura, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI

Localización geográfica de ganado utilizando modelos de propagación de señal y XBee

En este artículo se presentan los avances en una línea de investigación y desarrollo enfocada en la experimentación con aplicaciones de Redes de Sensores Inalámbricos para soportar servicios en un contexto de Ambientes Inteligentes. El objetivo de la línea, radica en el diseño e implantación de un prototipo harware/software basado en Redes de Sensores Inalámbricos (Wireless Sensor Networks WSN) para capturar la intensidad de las señales de los enrutadores móviles, y mediante el método de Trilateración, ayudar a la localización de ganado en un área determinada. El prototipo permite analizar distintos modelos de propagación y técnicas de estimación de distancia y visualizar los resultados en una interfaz web amigable. El prototipo está en su fase de prueba en laboratorio y de obtención de los primeros resultados en campo.Eje: Arquitectura, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI