Dynamical Modeling of the Unsteady Flow over a Flapping Wing by applying Proper Orthogonal Decomposition and System Identification to Particle Image Velocimetry Data

In this work a novel approach for the dynamical modeling of the unsteady flow over a pitching airfoil is considered. The technique is based on collecting instantaneous velocity field data of the flow using particle image velocimetry (PIV), applying image processing to these snapshots to locate the airfoil, filling the airfoil and its surface with proper velocity data, applying proper orthogonal decomposition (POD) to these post-processed images to compute the POD modes and time coefficients, and finally fitting a discrete time state space dynamical model to the trajectories of the time coefficients using subspace system identification (N4SID). The procedure is implemented using MATLAB for the data obtained from a NACA0012 airfoil, and the results show that the dynamical model obtained can represent the flow dynamics with acceptable accuracy

Dynamical modelling of the flow over a flapping wing using proper orthogonal decomposition and system identification techniques

A systematic approach for the dynamical modelling of the unsteady flow over a flapping wing is developed, which is based on instantaneous velocity field data of the flow collected using particle image velocimetry (PIV) and computational fluid dynamics (CFD) simulations. The location and orientation of the airfoil is obtained by image processing and the airfoil is filled with proper velocity data. Proper orthogonal decomposition (POD) is applied to these post-processed images to compute POD modes and time coefficients, and a discrete-time state-space dynamical model is fit to the trajectories of the time coefficients using subspace system identification (N4SID). The procedure is verified using PIV and CFD data obtained from a pitching NACA0012 airfoil. The simulation results confirm that the dynamical model obtained from the method proposed can represent the flow dynamics with acceptable accuracy

Experimental design and statistical modeling methodology for wind tunnel aerodynamics of an agile missile to improve the simulation accuracy and performance

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Wind tunnel testing is an essential procedure to investigate the aerodynamics forces and moments. In this paper, a methodology is presented to perform such test in an efficient way. Experimental design process is carried out before the testing in order to cover the flight regime as much as possible with the least possible number of tests. After the determination of the test matrix and conducting the wind-on tests, the modeling of the data is the next step. On that matter, two nonlinear modeling techniques are presented and compared with each other. First technique is the well-known Artificial Neural Networks (ANN) and the second one is relatively lesser known but a powerful modeling algorithm Multivariate Adaptive Regression Splines (MARS). After the data is modeled using both approaches, their statistical metrics are compared and the models are integrated into a high fidelity 6DoF equations of motion model. Since all this effort is to improve the simulation accuracy and performance, 6DoF simulations are performed using three different flight scenarios that cover the flight regime of the missile. Afterwards, obtained trajectory and flight parameters are compared. Finally, various flight conditions are produced and the models are evaluated in batch mode to see their performances in terms of computational speed

Kültürel Mirasın İzinde Ankara

Kentlerin belleği vardır. Sokakların, meydanların, binaların, kaldırımların, parkların, taşların ve ağaçların belleği... Cansız bina yığınından ve koşturan insanlardan ibaret gibi görünen kentlerin belleği... Elinizde tuttuğunuz bu kitap, o belleğin taşıyıcısı ve sürdürücüsü olan herkese ve herşeye adanmıştır. Bizi büyüten güzel Ankara'ya vefa borcumuzu ödeme çabasıdır bu derlem. Unutmaya ve unutturmaya karşı direnç, ayrıntılara ve belleğe bir övgüdür... Romanların, şiirlerin, mektupların, binaların, toprağın, heykellerin, yolların ve o yollarda yürüyenlerin içinde sakladığı, unutmadığı her ayrıntıya bir güzellemedir. Bin yılların kentine, Cumhuriyet'in başkentine sevgiyle kaleme alınmış bilimsel yazılardan ve tanıklıklardan meydana gelmiştir. Hacettepe Üniversitesi Tarihi ve Kültürel Mirası Araştırma Merkezi çatısı altında, Ankara'nın belleğine katkıda bulunmaktan mutluluk ve gurur duyuyoruz. Bu derlemin oluşmasına katkıda bulunan yazarlarımıza içtenlikle teşekkür ederiz