Optimización de la integridad estructural de las estaciones de ala de aeronaves de combate: un enfoque de análisis de elementos finitos

Modern fighter aircraft are equipped with multiple stations on the fuselage and under the wings to accommodate various external stores, both jettisonable and non-jettisonable. Each configuration undergoes airworthiness certification, including structural analysis of individual stations within the carriage flight envelope. This study focuses on the structural analysis of a fighter aircraft wing station within this specified envelope. To perform this analysis, the wing station is extracted from the comprehensive global wing model, creating a sub-model with equivalent stiffness properties. Utilizing ANSYS Workbench®, Finite Element Analysis (FEA) is conducted for critical load cases to determine the Factor of Safety (FoS). The initial analysis reveals that the wing station has an FoS of 1.2 under the maximum design load. Prestressed modal and buckling analyses indicate a 10% increase in stiffness due to stress-stiffening effects. To further enhance load-carrying capacity, parametric design changes are introduced. Increasing the bolt diameter from 8 mm to 10 mm raises the FoS to 1.33, resulting in an 8% increase in the maximum load-carrying capacity of the wing station. This comprehensive approach, employing FEA, ensures the wing’s structural integrity under static load conditions within the carriage envelope. The study\u27s findings support the wing station\u27s enhanced performance and contribute to safer and more efficient aircraft operations.Los aviones de combate modernos están equipados con múltiples estaciones en el fuselaje y debajo de las alas para acomodar varios almacenes externos, tanto descartables como no descartables. Cada configuración se somete a una certificación de aeronavegabilidad, incluido un análisis estructural de las estaciones individuales dentro de la envolvente de vuelo del transporte. Este estudio se centra en el análisis estructural de una estación de ala de un avión de combate dentro de esta envolvente especificada.Para realizar este análisis, la estación del ala se extrae del modelo global integral del ala, creando un submodelo con propiedades de rigidez equivalentes. Utilizando ANSYS Workbench®, se realiza un análisis de elementos finitos (FEA) para casos de carga críticos para determinar el factor de seguridad (FoS). El análisis inicial revela que la estación del ala tiene un FoS de 1,2 bajo la carga máxima de diseño. Los análisis modales y de pandeo pretensados indican un aumento del 10 % en la rigidez debido a los efectos de rigidez por tensión. Para mejorar aún más la capacidad de carga, se introducen cambios de diseño paramétrico. El cambio del diámetro del perno de 8 mm a 10 mm incrementa el FoS a 1,33, lo que da como resultado un aumento del 8 % en la capacidad máxima de carga de la estación del ala. Este enfoque integral, que emplea FEA, garantiza la integridad estructural del ala bajo condiciones de carga estática dentro de la envolvente del carro. Los hallazgos del estudio respaldan el rendimiento mejorado de la estación del ala y contribuyen a operaciones de aeronaves más seguras y eficientes

Strength properties of polymer mortar panels using methyl methacrylate solution of waste expanded polystyrene as binder

The present study examines the applicability of polymermortarpanels using a methylmethacrylate (MMA) solution of wasteexpandedpolystyrene (EPS) to develop effective recycling processes for the EPS, referring to the strengthproperties of a polymer-impregnated mortarpanel with almost the same performance as commercial products. An MMA solution of EPS is prepared by dissolving EPS in MMA, and unreinforced and steel fiber-reinforced polymermortars are mixed using the EPS-MMA-based solution as a liquid resin or binder. Polymermortarpanels (PMPs) using the EPS-MMA-based polymermortars without and with steel fiber and crimped wire cloth reinforcements and steel fiber-reinforced polymer-impregnated mortarpanel (PIMP) are prepared on trial, and tested for flexural behavior under four-point loading. The EPS-MMA-based PMPs are more ductile than the PIMP, and have a high load-bearing capacity. Consequently, they can replace PIMP in practical applications

ESCRT function in cytokinesis: location, dynamics and regulation by mitotic kinases

Mammalian cytokinesis proceeds by constriction of an actomyosin ring and furrow ingression, resulting in the formation of the midbody bridge connecting two daughter cells. At the centre of the midbody resides the Flemming body, a dense proteinaceous ring surrounding the interlocking ends of anti-parallel microtubule arrays. Abscission, the terminal step of cytokinesis, occurs near the Flemming body. A series of broad processes govern abscission: the initiation and stabilisation of the abscission zone, followed by microtubule severing and membrane scission—The latter mediated by the endosomal sorting complex required for transport (ESCRT) proteins. A key goal of cell and developmental biologists is to develop a clear understanding of the mechanisms that underpin abscission, and how the spatiotemporal coordination of these events with previous stages in cell division is accomplished. This article will focus on the function and dynamics of the ESCRT proteins in abscission and will review recent work, which has begun to explore how these complex protein assemblies are regulated by the cell cycle machinery

Selective Subtraction: An Extension of Background Subtraction

Background subtraction or scene modeling techniques model the background of the scene using the stationarity property and classify the scene into two classes of foreground and background. In doing so, most moving objects become foreground indiscriminately, except for perhaps some waving tree leaves, water ripples, or a water fountain, which are typically learned as part of the background using a large training set of video data. Traditional techniques exhibit a number of limitations including inability to model partial background or subtract partial foreground, inflexibility of the model being used, need for large training data and computational inefficiency. In this thesis, we present our work to address each of these limitations and propose algorithms in two major areas of research within background subtraction namely single-view and multi-view based techniques. We first propose the use of both spatial and temporal properties to model a dynamic scene and show how Mapping Convergence framework within Support Vector Mapping Convergence (SVMC) can be used to minimize training data. We also introduce a novel concept of background as the objects other than the foreground, which may include moving objects in the scene that cannot be learned from a training set because they occur only irregularly and sporadically, e.g. a walking person. We propose a selective subtraction method as an alternative to standard background subtraction, and show that a reference plane in a scene viewed by two cameras can be used as the decision boundary between foreground and background. In our definition, the foreground may actually occur behind a moving object. Our novel use of projective depth as a decision boundary allows us to extend the traditional definition of background subtraction and propose a much more powerful framework. Furthermore, we show that the reference plane can be selected in a very flexible manner, using for example the actual moving objects in the scene, if needed. We present diverse set of examples to show that: (i) the technique performs better than standard background subtraction techniques without the need for training, camera calibration, disparity map estimation, or special camera configurations; (ii) it is potentially more powerful than standard methods because of its flexibility of making it possible to select in real-time what to filter out as background, regardless of whether the object is moving or not, or whether it is a rare event or a frequent one; (iii) the technique can be used for a variety of situations including when images are captured using stationary cameras or hand-held cameras and for both indoor and outdoor scenes. We provide extensive results to show the effectiveness of the proposed framework in a variety of very challenging environments

How Socially Deviant and Socially Agreeing Stereotypes of Computer Scientists Contribute to Middle School Boys’ Identity and Career Intentions

Like other STEM fields, computer science (CS) lacks representation of minority groups both in the number of bachelor’s degrees obtained and the number of individuals in the CS workforce. Out-o- -school CS programs are often designed with the intent to inspire young people to pursue careers in CS. Much of this programming focuses on developing student interest in CS and CS careers. Nevertheless, it is not well understood how the stereotypes that children hold about computer scientists contribute to CS interest and career choice. In this study we set out to examine the complex relationships between CS interest, held stereotypes, and CS career choice. We surveyed minority male participants in an after-school CS program (N = 91). We tested structural equation models and confirmed that CS interest and socially divergent stereotypes of computer scientists play unique and contrary roles in young boys’ career decision-making process. The model with best fit suggests informal CS programs should include curriculum to disperse participants’ socially divergent stereotypes about computer scientists rather than targeting CS interest alone, particularly if a goal is to inspire diverse young people to pursue careers in CS

A complex network of interactions between mitotic kinases, phosphatases and ESCRT proteins regulates septation and membrane trafficking in S. pombe

Cytokinesis and cell separation are critical events in the cell cycle. We show that Endosomal Sorting Complex Required for Transport (ESCRT) genes are required for cell separation in Schizosaccharomyces pombe. We identify genetic interactions between ESCRT proteins and polo and aurora kinases and Cdc14 phosphatase that manifest as impaired growth and exacerbated defects in septation, suggesting that the encoded proteins function together to control these processes. Furthermore, we observed defective endosomal sorting in mutants of plo1, ark1 and clp1, as has been reported for ESCRT mutants, consistent with a role for these kinases in the control of ESCRT function in membrane traffic. Multiple observations indicate functional interplay between polo and ESCRT components: firstly, two-hybrid in vivo interactions are reported between Plo1p and Sst4p, Vps28p, Vps25p, Vps20p and Vps32p; secondly, co-immunoprecipitation of human homologues of Vps20p, Vps32p, Vps24p and Vps2p by human Plk1; and thirdly, in vitro phosphorylation of budding yeast Vps32p and Vps20p by polo kinase. Two-hybrid analyses also identified interactions between Ark1p and Vps20p and Vps32p, and Clp1p and Vps28p. These experiments indicate a network of interactions between ESCRT proteins, plo1, ark1 and clp1 that coordinate membrane trafficking and cell separation in fission yeast