Challenges, Ideas, and Innovations of Joined-Wing Configurations: A Concept from the Past, an Opportunity for the Future

Diamond Wings, Strut- and Truss-Braced Wings, Box Wings, and PrandtlPlane, the so-called “Join-edWings”, represent a dramatic departure from traditional configurations. Joined Wings are characterized by a structurally overconstrained layout which significantly increases the design space with multiple load paths and numerous solutions not available in classical wing systems. A tight link between the different disciplines (aerodynamics, flight mechanics, aeroelasticity, etc.) makes a Multidisciplinary Design and Optimization approach a necessity from the early design stages. Researchers showed potential in terms of aerodynamic efficiency, reduction of emissions and superior performances, strongly supporting the technical advantages of Joined Wings. This review will present these studies, with particular focus on the United States joined-wing SensorCraft, Strut- and Truss- Braced Wings, Box Wings and PrandtlPlane

Assess the Accuracy of the Variational Asymptotic Plate and Shell Analysis Using the Generalized Uni

The accuracy of the Variational Asymptotic Plate and Shell Analysis (VAPAS) is assessed against several higher order, zig zag and layerwise theories generated by using the invariant axiomatic framework denoted as Generalized Unified Formulation (GUF). These theories are also compared against the elasticity solution developed for the case of a sandwich structure with high Face to Core Stiffness Ratio. GUF allows to use an infinite number of axiomatic theories (Equivalent Single Layer theories with or without zig zag effects and Layerwise theories as well) with any combination of orders of the displacements and it is an ideal tool to precisely assess the range of applicability of the Variational Asymptotic Plate and Shell Analysis or other theories in general. In fact, all the axiomatic theories generated by GUF are obtained from the kernels or fundamental nuclei of the Generalized Unified Formulation and changing the order of the variables is “naturally” and systematically done with GUF. It is demonstrated that VAPAS achieves accuracy comparable to a fourth (or higher) order zig-zag theory or lower-order layerwise theories with the least number degrees of freedom. The differences between the axiomatic Zig-zag models and VAPAS are also assessed. Range of applicability of VAPAS will be discussed in detail and guidelines for new developments based on GUF and VAPAS are provided

Properties and numerical solution of an integral equation system to minimize airplane drag for a multiwing system

We consider an open multiwing system, composed of N 2 disjoint openplane curves, not necessarily symmetric, and examine the corresponding (con-strained) induced drag minimization problem. To this end, we first derive theassociated Euler-Lagrange system of equations, which is then reduced to anequivalent system of Cauchy singular integral equations. By generalizing a pre-vious approach of ours for the case of a single open wing, we obtain existenceand uniqueness results for the problem solution in a product of weighted Sobolevtype spaces. This system is then solved by applying to it a collocation-quadraturemethod. For this, we prove stability and derive corresponding error estimates.Finally, to test the efficiency of the proposed numerical method, we apply it tosome multiwing system

Nonlinear Analysis of PrandtlPlane Joined Wings: Effects of Anisotropy

Structural geometrical nonlinearities strongly affect the response of joined wings: it has been shown that buckling evaluations using linear methods are unreliable, and only a fully nonlinear stability analysis can safely identify the unstable state. This work focuses on the understanding of the main physical mechanisms driving the wing system's response and the snap-buckling instability. Several counterintuitive effects typical of unconventional nonplanar wing systems are discussed and explained. In particular, an appropriate design of the joint-to-wing connection may reduce the amount of bending moment transferred, and this is shown to eventually improve the stability properties, although at price of a reduced stiffness. It is also demonstrated that the lower-to-upper-wing stiffness ratio and the torsional-bending coupling, due to both the geometrical layout and anisotropy of the composite laminates, present a major impact on the nonlinear response. The findings of this work could provide useful indications to develop effective aeroelastic reduced-order models tailored for airplane configurations experiencing important geometric nonlinearities such as PrandtlPlane, truss-braced and strut-braced wings, and sensorcraft

Generalized Unified Formulation shell element for functionally graded Variable-Stiffness Composite Laminates and aeroelastic applications

Composite materials have been extensively used in engineering thanks to their lightweight, superior mechanical performances and possibility to tailor the structural behavior, increasing the available design space. Variable Angle Tow (VAT) structures exploits this advantage by adopting a curvilinear patterns for the fibers constituting the lamina. This work, for the first time, extends the Generalized Unified Formulation (GUF) to the case of fourth-order triangular shell elements and VAT composites. Functionally graded material properties in both the thickness and in-plane directions are also possible. The finite element has been formulated with layers of variable thickness with respect to the in-plane coordinates. GUF is a very versatile tool for the analysis of Variable Stiffness Composite Laminates (VSCLs): it is possible to select generic element coordinate systems and define different types of axiomatic descriptions (Equivalent Single Layer, Layer Wise, and Zig-Zag enhanced formulations) and orders of the thickness expansions. Each displacement is independently treated from the others. All the infinite number of theories that can be generated with GUF are obtained by expanding six theory-invariant kernels (formally identical for all the elements), allowing a very general implementation. Finally, the possibility of tailoring the theory/order to increase the accuracy in desired directions makes the GUF VAT capability a very powerful tool for the design of aerospace structures

Quantifying Masking Fault-Tolerance via Fair Stochastic Games

We introduce a formal notion of masking fault-tolerance between probabilistic transition systems using stochastic games. These games are inspired in bisimulation games, but they also take into account the possible faulty behavior of systems. When no faults are present, these games boil down to probabilistic bisimulation games. Since these games could be infinite, we propose a symbolic way of representing them so that they can be solved in polynomial time. In particular, we use this notion of masking to quantify the level of masking fault-tolerance exhibited by almost-sure failing systems, i.e., those systems that eventually fail with probability 1. The level of masking fault-tolerance of almost-sure failing systems can be calculated by solving a collection of functional equations. We produce this metric in a setting in which one of the player behaves in a strong fair way (mimicking the idea of fair environments).Comment: In Proceedings EXPRESS/SOS2023, arXiv:2309.05788. arXiv admin note: substantial text overlap with arXiv:2207.0204

Uso de la librería OpenCV para la segmentación y clasificación de imágenes de radar meteorológico

Fil: Demasi, Maximiliano David. Servicio Meteorológico Nacional. Dirección Nacional de Ciencia e Innovación en Productos y Servicios. Dirección de Productos de Modelación Ambiental y de Sensores Remotos; Argentina.Fil: Vidal, Luciano. Servicio Meteorológico Nacional. Dirección Nacional de Ciencia e Innovación en Productos y Servicios. Dirección de Productos de Modelación Ambiental y de Sensores Remotos; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y Los Océanos; Argentina.En la actualidad existen numerosas herramientas orientadas al procesamiento y análisis de imágenes de uso libre que ofrecen capacidades destacables para su explotación en el ámbito de la meteorología por radar. En este contexto, una de las librerías más conocidas es OpenCV siendo ésta de gran utilidad a la hora de realizar tareas de visión artificial orientada a imágenes. En la presente Nota Técnica se muestra un ejemplo de uso de dicha librería para la segmentación y clasificación de imágenes COLMAX en formato PNG disponibles en el archivo de imágenes de radar del Servicio Meteorológico Nacional de Argentina.At present, there are many free image processing and analysis tools that offer remarkable capabilities for radar meteorology. In this context, one of the best known libraries is OpenCV, which is very useful for image-oriented computer vision tasks. This Technical Note shows an example of the use of this library for the segmentation and classification of COLMAX images in PNG format available in the radar image archive of the National Meteorological Service of Argentina

Exploratory Structural Investigation of a Hawkmoth-Inspired MAV’s Thorax

Manduca Sexta present excellent flight performances which make this insect an ideal candidate for bio-inspired engineered micro air vehicles. The actual insect presents an energetically very efficient thorax-wing flight system which needs to be fully understood for an effective design of artificial flying machines. This work discusses a preliminary finite element model which simulates the thorax-wing system and the muscles involved in the flapping motion. Both upstroke and downstroke conditions are statically analyzed with the application of load sets that simulate the contractions of the dorso-ventral and dorso-longitudinal muscles (indirect flight). Comparison with commercial software and experimental results is also presented and discussed