Showing papers in "Aerospace Science and Technology in 2012"

TL;DR: A new optimization algorithm called multi-frequency vibrational genetic algorithm (mVGA) that can be used to solve the path planning problems of autonomous unmanned aerial vehicles (UAVs) is significantly improved.

TL;DR: In this article, the effects of the geometric parameters, i.e., the upstream depth, the downstream depth, and the swept angle, on the drag force of the cavity flameholder for a heated flow were investigated using the variance analysis method.

TL;DR: In this paper, the authors presented a kinematic, dynamic analysis and control methods to predict the deployment motions of the hoop truss deployable antenna, which can be applied to carry out the position, velocity and acceleration analysis of any point on the structure.

TL;DR: In this article, a combined nonlinear observer and back-stepping technique is adopted for designing a dynamic output-feedback controller that provides stable tracking of the velocity and altitude reference trajectories.

TL;DR: In this article, the robust Kalman filtering problem for discrete-time nonlinear systems with norm-bound parameter uncertainties is studied and a Riccati equation is derived in the presence of both the parameter uncertainties and the linearization errors.

TL;DR: In this article, an approach based on the Eulerian two-phase flow theory to numerically simulate ice accretions on an aircraft wing is developed, where the air flowfield is obtained through Euler flow computation.

TL;DR: In this paper, a novel attitude stabilization control scheme for flexible spacecraft, based on the semi-globally input-to-state stable (ISS) concept, is presented, where the modified Rodrigues parameters described attitude system is considered in the presence of unknown parameter uncertainties, external disturbances and even control input saturation.

TL;DR: In this paper, the authors investigated the design, theoretical study, numerical modelling and experiment of a novel flapping wing rotor for micro aerial vehicles (MAV). Attention was firstly focused on the design of a simple, reliable and lightweight configuration of the flappingwing structure and the rotor.

TL;DR: The optimization framework is first applied to various optimization problems in hover starting with the easy task of optimizing the twist rate for the 7A model rotor, and a multi-objective optimization for Twist is carried out in order to find a compromise design between the conflicting goal functions for hover and forward flight.

TL;DR: The work establishes the superiority of feed-forward backpropagation neural nets for the airfoil geometry determination due to good function approximation properties of the neural architecture and the use of Bezier–PARSEC 3434 parameterization scheme.

TL;DR: In this article, the authors used the LS-DYNA to simulate an HRAM event created by a steel spherical projectile impacting a partially water-filled aluminium square tube, and the ALE formulation was employed to reproduce the event.

TL;DR: In this paper, an efficient gradient-based optimization technique is used to optimize 2D contour bump parameters including the length, the maximum height, the bump position via shock location, and the crest position via bump and also the jet actuation parameters such as mass flow coefficient, suction/blowing angle, actuation location over the upper surface of the airfoil.

TL;DR: In this article, a novel experimental and computational aerodynamic database for a complete helicopter has been generated for the GOAHEAD project, where the primary objective of the five-year long project was to validate state-of-the-art CFD solvers developed for rotorcraft aerodynamic problems against experimental measurements.

TL;DR: In this paper, the authors developed a methodology and simulation tool for a preliminary yet accurate evaluation of airplane dynamical response and stability and control characteristics due to icing, using only basic mass properties, configuration, and propulsion data, together with known icing data obtained for similar configurations.

TL;DR: In this paper, a 3D trapped vortex combustor (TVC) cavity was investigated numerically by using shear stress transport (SST) k − ω model and eddy dissipation combustion model.

TL;DR: A continuous finite-time-convergent differentiator is presented based on a strong Lyapunov function that can reduce chattering phenomenon sufficiently than normal sliding mode differentiator, and the outputs of signal tracking and derivative estimation are all smooth.

TL;DR: In this article, a 3D dynamic stall was observed on the rotor of a fully equipped subscale helicopter model in a wind tunnel and the small-scale shear layer vortices that constitute the large-scale dynamic stall vortex were identified and localised.

TL;DR: In this paper, a robust multi-objective filter is constructed for the concerned Inertial Navigation System with disturbance rejection and attenuation performance, where the drift estimations are applied to reject the inertial sensor drifts and mixed H 2 /H ∞ filter is adopted to attenuate Gaussian noises and norm bounded disturbances.

TL;DR: In this article, the authors investigated the role of the leading edge details of the X-31 wind tunnel model in obtaining the vortical flow phenomena observed in the wind tunnel and the results obtained for selected test conditions measured during test run VN01004 (M = 0.18 and Re m. a. c. = 2.07 × 10 6 ) were discussed.

TL;DR: In this article, five different types of six layered GFRP laminates were prepared from three types of resin systems and compared for their intermediate velocity bullet impact response and vibration damping characteristics.

TL;DR: In this paper, a family of multi-block CFD meshes was developed at the University of Liverpool to work with the sliding-plane method, and a more advanced multilayer topology was developed for the post-wind tunnel phase of the project, which allowed main and tail rotors to be included.

TL;DR: In this article, the planform, profile, and cross-sectional views of the wing-tip region of a half-wing model with an aspect ratio of 3.2 and three different wing configurations, namely, square-cut, simple fairing, and Whitcomb's full winglet wingtip, were visualized at various angles of attack using smoke-wire visualization technique.

TL;DR: In this paper, a nonlinear constrained optimization scheme based on Sequential Quadratic Programming (SQP) is used to generate the optimal maneuver motions for small aircraft in pre-and post-stall regimes.

TL;DR: In this paper, the authors proposed a flexible method for interpolating a continuous load distribution in order to identify the full-field aerodynamic load from strain data acquired at a number of discrete points.

TL;DR: In this article, the effects of spatially uncertain material properties on the aeroelastic response predictions (e.g., rotating frequencies, vibratory loads, etc.) of composite helicopter rotor are investigated.

TL;DR: In this paper, the negative impact of low-level flight is examined and a relationship between fuel consumption and altitude established using real flight data and the GA technique, and corresponding results exhibit similar model coefficients and low residuals for three of four flights.

TL;DR: In this article, the authors investigated the lean blowout performance of several combustors which utilized trapped vortex in the cavity to improve the flame stability and found that the minimum pressure drop across the combustor occurred when the height to length (Hf / L ) ratio was 08; and very low overall LBO equivalence ratios were observed over a wide range of primary air flows at the same H/L ratio.

TL;DR: The new algorithm emphasizes the use of an aerodynamic design prediction based on a global and a local surrogate modelling in genetic algorithm structure and significantly decreases the required CFD calls in multi-element airfoil optimization; more than 70% in active flow control parameter optimization; and approximately 50% in direct shape optimization problem.

TL;DR: The paper presents the star tracker system, details some newly developed algorithms and analyzes the test results, as well as verifying the performance of the sensor in real-time End-to-End tests.

TL;DR: In this article, the first attempt to exploit the GOAHEAD data base to perform a code-to-code evaluation on complete helicopter aerodynamics is presented and compared to experimental measurements.