1,720,952 research outputs found
A Semi-Empirical Aerodynamic Model Based on Dynamic Stall for Rigid-Framed Delta Kites during Figure-of-Eight Maneuvers
No full textGreen Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
Determination of Optimal Control Laws in Airborne Wind Energy Scenarios With a Self-Consistent Kite Dynamics Model
No full textLos mitos de la nueva y la vieja Rusia. Historias. Revista de la Dirección de Estudios Históricos. Num. 85 (2013) mayo-agosto
No full textRodric Braithwaite (Londres, 1932) es autor de varios libros que se derivan de su pasión y conocimiento de Rusia, así como de su experiencia como embajador en Moscú entre 1988 y 1992: El compromiso de Rusia (icipe, traducción de Agustín Vergara Sharp y Míriam Rodríguez Murphy, 1995), Russia and Euerope (1999), Across the Moscow River: The World Turned Upside Down (2003) y Moscú 1941: una ciudad y su pueblo en guerra (Crítica, traducción de Gonzalo G. Djembé y Francesc Fernández Sánchez, 2006). Braithwaite estudió letras francesas y rusas en la Universidad de Cambridge, y en 1995 se sumó al servicio diplomático inglés. Tomado del Financial Times del 22 de diciembre de 2011
Application of the Estimation-Before-Modeling Method to the Aerodynamic Characterization of Power Kites
No full textEl ejemplar del Geka seiso (1791) de la Colección Francisco Guerra por José Luis Gonzalo Sánchez-Molero
No full textDesde 2007 la Biblioteca Histórica Marqués de Valdecilla conserva un ejemplar del Geka seiso, un libro xilográfico japonés impreso en el siglo XVIII. Su título original chino es Waik'o Cheng Tsung, o Método ortodoxo de la cirugía, en español. Esta tratado médico fue escrito al inicio del siglo anterior por Chen Shih-kung, o Chen Shigong, (c. 1555-1636), y en 1791 fue editado de nuevo en Japón por el médico imperial Ogino Gengai (1737-1806). Este ejemplar complutense proviene de la colección de Francisco Guerra Pérez-Carral. En este artículo se estudian tres aspectos del Geka seiso, en un orden cronológico inverso. Primero, su adquisición por el doctor Guerra, quien lo compró en Miami (1990), procedente el volumen de la colección del doctor norteamericano Otto Orren Fisher. A continuación se analiza el contenido de esta obra, publicada por vez primera en 1611, en China. En ella su autor (Chen Shigong) incluyó sus famosos preceptos profesionales y éticos: Los cinco mandamientos y las diez exigencias. Por último se estudian, por un lado, las circunstancias históricas de esta edición en 1791, relacionada probablemente con el proceso político de restauración de los estudios Chu Hsi, y por otro lado el proceso técnico de su impresión, realizado en Kyoto por Hayashi Gonbe, Hayashi Ihe y Takemura Kahe. Finalmente se describen y comentan algunas de las características materiales de este ejemplar del Geka seiso, para su mejor comprensión por un lector occidental.Since 2007, the Historical Library "Marqués de Valdecilla" preserves a copy of Geka seiso, a Japanese blockbook printed in the eighteenth century. Its original title Chinese is Waik'o Cheng Tsung, or Orthodox method of surgery, in English. This medical treatise was written at the beginning of the previous century by Chen Shih-kung, or Chen Shigong, (c. 1555-1636), and in 1791 was printed again in Japan by the imperial doctor Gengai Ogino (1737-1806). This complutense copy is from the collection Francisco Perez-Carral Guerra. This article looks at three aspects of Geka seiso, in a reverse chronological order. First, its acquisition by Dr. Guerra, who bought it in Miami (1990), from the volume of the collection of American Dr. Otto Orren Fisher. Next it analyzes the content of this work, first published in China (1611). in this edition the author (Chen Shigong) included his famous professional and ethical precepts: The Five Commandments and Ten Tenets for Physicians. Finally, we study the historical circumstances of this edition in 1791, probably related to the political process of restoration of Chu His's studies and too the technical process of printing, held in Kyoto by Gonbad Hayashi, Ihe Hayashi and Takemura Kahe. Finally, it describes and discusses some of the material characteristics of this copy of Geka seiso for a better understanding of Western readers
Flight-Path Reconstruction and Flight Test of Four-Line Power Kites
Full text linkA flight-path reconstruction algorithm for tethered aircraft, which is based on an extended Kalman filter, is presented. The algorithm is fed by the measurements of a set of onboard and ground-based instruments and provides the optimal estimation of the system state-space trajectory, which includes typical aircraft variables such as position and velocity, as well as an estimation of the aerodynamic force and torque. Therefore, it can be applied to closed-loop control in airborne wind energy systems and it is a first step toward aerodynamic parameter identification of tethered aircraft using flight-test data. The performance of the algorithm is investigated by feeding it with real flight data obtained from a low-cost and highly portable experimental setup with a four-line kite. Several flight tests, which include pullup and lateral-directional steering maneuvers with two kites of different areas, are conducted. The coherence of the estimations provided by the filter, such as the kite state-space trajectory and aerodynamic forces and torques, is analyzed. For some standard variables, such as kite Euler angles and position, the results are also compared with a second independent onboard estimator.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
Flight Testing, Aerodynamic Parameter Identification and Dynamic Simulation of Rigid and Flexible Kites Applied to Airborne Wind Energy systems
No full textSimulation, state estimation, and aerodynamic parameter identification from in-flight data are actual research topics in AWE [1,2]. This work summarizes the status of four infrastructures developed at Universidad Carlos III de Madrid that are related with them: (i) a portable experimental rig for the acquisition of flight data like kite position, velocity, Euler angles, angular velocity, aerodynamic speed, angle of attack and sideslip angles, tether tensions, and wind velocity, (ii) an estimator of the state of the system, including the aerodynamic force and torque (iii) an optimization algorithm to compute the aerodynamic parameters from the estimated state variables, and (iv) the open-source simulator LAKSA, that contains modules aimed at the dynamic simulation and control of fly-gen and ground-gen generation systems, 2- line acrobatic kites, four-line kitesurf kites, and a train of N stacked kites.greenWind Energ
A lagrangian flight simulator for airborne wind energy systems
Full text linkA parallelized flight simulator for the dynamic analysis of airborne wind energy (AWE) systems for ground- and fly-generation configurations is presented. The mechanical system comprises a kite or fixed-wing drone equipped with rotors and linked to the ground by a flexible tether. The time-dependent control vector of the simulator mimics real AWE systems and it includes the length of the main tether, the geometry of the bridle, the torque of the motor controllers of the rotors, and the deflections of ailerons, rudder and elevator. The use of a lagrangian formulation with a minimal coordinate approach and discretizing the main tether as a chain of inelastic straight rods linked by ideal (dissipative-less) rotational joints, yielded a non-stiff set of ordinary differential equations free of algebraic constraints. Several verification tests, including a reel-in maneuver that admits an analytical solution, are presented. The efficiency of the parallelization with the number of tether segments, and trade-off analysis of the lagrangian and hamiltonian formulations are also considered. The versatility of the simulator is highlighted by analyzing two maneuvers that are relevant for AWE scenarios. First, the simulator is used to compute periodic figure-of-eight trajectories with an open-loop control law that varies the geometry of the kite’s bridle, as frequently done in ground-generation AWE systems. Second, an unstable equilibrium state of a tethered drone equipped with two rotors for energy harvesting is stabilized by implementing a closed-loop control strategy for the deflection of the control aerodynamic surfaces.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
Modeling and dynamics of a two-line kite
Full text linkA mathematical model of a kite connected to the ground by two straight tethers of varying lengths is presented and used to study the traction force generated by kites flying in cross-wind conditions. The equations of motion are obtained by using a Lagrangian formulation, which yields a low-order system of ordinary differential equations free of constraint forces. Two parameters are chosen for the analysis. The first parameter is the wind velocity. The second parameter is one of the stability derivatives of the aerodynamic model: the roll response to the sideslip angle, known also as effective dihedral. This parameter affects significantly the lateral dynamics of the kite. It has been found that when the effective dihedral is below a certain threshold, the kite follows stable periodic trajectories, and naturally flies in cross-wind conditions while generating a high tension along both tethers. This result indicates that kite-based propulsion systems could operate without controlling tether lengths if kite design, including the dihedral and sweep angles, is done appropriately. If both tether lengths are varied out-of-phase and periodically, then kite dynamics can be very complex. The trajectories are chaotic and intermittent for values of the effective dihedral below a certain negative threshold. It is found that tether tensions can be very similar with and without tether length modulation if the parameters of the model are well-chosen. The use of the model for pure traction applications of kites is discussed.Wind Energ
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