Palacios J.I.,SENER Ingenieria y Sistemas |
Romeu J.,Polytechnic University of Catalonia |
Balastegui A.,Polytechnic University of Catalonia
Journal of Vibration and Acoustics, Transactions of the ASME | Year: 2010
Global active control of sound can be achieved inside enclosures under low modal acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system in which secondary acoustic sources (loudspeakers) and pressure transducers (microphones) as error sensors are used, several optimization strategies have been proposed. These strategies usually rely on partial approximation to the problem, focusing on the study of number and localization of secondary sources without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here for tonal global active noise control of steady states comprises two steps; the first is rather common for this sort of problem and its goal is to find the best locations for secondary sources and their strengths by minimizing the potential energy of the enclosure. The second step is the localization of the error transducer, which ensures the results of the first step. It is analytically demonstrated that for a single input single output system, the optimum location of error transducers is at a null pressure point of the optimally attenuated acoustic field. It is also shown that in a real case, the optimum position is that of a minimum of the optimally attenuated acoustic field. Finally, a numerical validation of this principle is carried out in a parallelipedic enclosure. © 2010 American Society of Mechanical Engineers.
Ismail M.,SENER Ingenieria y Sistemas |
Ismail M.,Zagazig University |
Ismail M.,Polytechnic University of Catalonia |
Rodellar J.,Polytechnic University of Catalonia |
Casas J.R.,Polytechnic University of Catalonia
Advances in Materials Science and Engineering | Year: 2016
This paper introduces a recent seismic isolation system, named Roll-in-Cage (RNC) isolator, for efficient protection of bridges against destructive earthquakes. The RNC isolator is a rolling-based isolation system with several integrated features in a single unit providing all the necessary functions of vertical rigid support, horizontal flexibility, full stability, hysteretic energy dissipation, and resistance to minor vibration loads. Besides, it is distinguished by a self-stopping (buffer) mechanism to limit the peak bearing displacement under abrupt severe excitations, a linear gravity-based self-recentering mechanism to prevent permanent dislocations after excitations, and a notable resistance to axial tension. A three-span box-girder prestressed concrete bridge is investigated under a set of different destructive real and synthetic earthquakes including near-fault, long-period, and pulse-like ground motions. As a performance measure, the responses of isolated and nonisolated cases are compared. In addition, the RNC isolator's behavior is then compared with those of other isolation systems including HDB, FPS, and LRB. The results confirmed that the RNC isolator has a superior behavior in achieving a balance between the peak displacements and accelerations of the isolated deck, relative other isolation systems, besides being the most (relatively) efficient isolator in the great majority of studies performed. © 2016 Mohammed Ismail et al.
Martinez P.,CIEMAT |
Moreno C.,CIEMAT |
Martinez I.,SENER Ingenieria y Sistemas |
Fusion Engineering and Design | Year: 2012
The Permeator Against Vacuum (PAV) has been conceived as the simplest, cost effective and reliable technology system dedicated to tritium extraction from breeding liquid metals. An optimal design of a PAV requires a detailed hydraulic design optimization for established operational ranges (HCLL at low velocities of ∼1 mm/s or DCLL in the ranges of tens of cm/s). The present work analyses the PAV extraction efficiency dependency on the design parameters as optimum on-line Tritium Extraction System (TES). Three different models have been built for that purpose: one through physically refined 1D tritium transport computation using TMAP7 (unique simulation tool with QA for ITER); and two further detailed models on 2D/3D FEM tool (COMSOL Multi-physics 4.0). The geometry used in this work is a simplification of Fuskite ® conceptual design developed at CIEMAT, consisting of a set of cylindrical and concentric α-Fe double membranes enclosing a vacuumed space and in contact with in-pipe flowing LiPb eutectic. The aim of this paper is to give the first steps to establish the optimal design parameters of a PAV and evaluate the state-of-the-art of these models. © 2012 Elsevier B.V.
Navarro-Cavalle J.,Technical University of Madrid |
Merino M.,Charles III University of Madrid |
Ahedo E.,Charles III University of Madrid |
Ruiz M.,SENER Ingenieria y Sistemas |
Sanchez V.,SENER Ingenieria y Sistemas
50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference 2014 | Year: 2014
This work preliminarily designs the main subsystems of a high power class Helicon Thruster. The assessment of thruster dimensions and performances is reached through fluid simulations of the internal and external plasma flows, and separately accounting for the wave-plasma coupling phenomena. These results are shown as requirements/constraints for the design of the radio-frequency subsystem, the magnetic field assembly, the thermal control and the propellant management subsystems. The guidelines for a good design of each subsystem are carefully explored and conclusions are reported. © 2014 by the authors.
Branco J.,GMV Inc |
Barrena V.,GMV Inc |
Olmos D.E.,GMV Inc |
Castellani L.T.,SENER Ingenieria y Sistemas |
Cropp A.,European Space Agency
Annual Review of Earth and Planetary Sciences | Year: 2015
PROBA-3 will demonstrate technologies and techniques for precise Formation Flying of two spacecraft. This paper describes its Formation Flying Navigation system for relative position and velocity determination. A Coronagraph spacecraft carries fine relative position metrology and higher-thrust propulsion, and an Occulter spacecraft carries fine low thrust actuators. The two spacecraft communicate data to each other through an Inter-Satellite Link with an associated delay. A relative GPS solution is also available for a period around the perigee pass. The Formation Flying Navigation system is part of the Formation Flying Software which commands the formation. It collects data from the sensors and actuation commands, synchronizes them to a common correction time, and processes them in an Extended Kalman Filter which makes use of a model of the dynamics of relative motion in elliptical orbits. This article provides an overview of the mission and the challenges posed to the relative navigation function design, and describes, in high level, the developed solutions that constitute the preliminary design of the Formation Flying Navigation System. Special emphasis is given to the solutions for handling the synchronization and processing of information from a high number of sources, in two spacecraft which communicate through an Inter Satellite link and are thus subject to significant latencies. © Springer International Publishing Switzerland 2015.
Huguenet P.,SENER Ingenieria y Sistemas |
Coll A.B.,SENER Ingenieria y Sistemas |
Gonzalez E.T.,SENER Ingenieria y Sistemas
19th AIAA/CEAS Aeroacoustics Conference | Year: 2013
This document presents a methodology developed for reducing the total weight of a noise reduction solution with a minimum impact on acoustic performances. This methodology is based on a procedure which identifies, from an optimized solution, the less contributive structural elements to cabin noise. By combining acoustical concepts such as Frequency Response Function (FRF), Modal Participation Factor (MPF) and Modal Acoustic Transfer Vector (MATV), in addition to optimization tools such as Nastran SOL 200, the proposed methodology leads to a significant reduction in weight of the solution with a limited impact on noise reduction values thus obtaining a more effective solution.
Kerr M.,Deimos Space S.L.U. |
Haya R.,Deimos Space S.L.U. |
Penin L.F.,Deimos Space S.L.U. |
de Zaiacomo G.,Deimos Space S.L.U. |
And 2 more authors.
AIAA Guidance, Navigation, and Control Conference 2012 | Year: 2012
The Intermediate eXperimental Vehicle (IXV) re-entry GNC is tasked with stabilising and manoeuvring the IXV from the Entry Interface Point (EIP, 120 km altitude) suborbital trajectory conditions to the deployment of a 3 stage (supersonic drogue, subsonic drogue and a main parachute) parachute system. The re-entry GNC is comprised of the Guidance, Navigation and Control functions, which are scheduled via a Flight Management function that interfaces the GNC with the vehicle's mode vehicle management (MVM). Within re-entry GNC responsibilities there is also the design and validation of the Descent and Recovery System (DRS) triggering algorithm, which autonomously triggers the extraction of the supersonic parachute. The IXV is a lifting body with a lift-to-drag ratio of 0.7 in the hypersonic regime and, distinct from other re-entry vehicles such as ARD and Orion, is actuated through the combination of two body flaps mounted at the aft windward side of the vehicle and RCS thrusters. The challenges for the IXV re-entry GNC system design are common to those for re-entry vehicles performing a first flight, with the re-entry GNC required to be robust to high levels of uncertainty in the vehicle dynamics. This paper describes the IXV re-entry G&C and DRS triggering algorithms at the current IXV programme status of Phase D, including the assessment of the re-entry GNC performance using the IXV functional engineering simulation developed for the IXV programme. s© 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Gabarda S.,CSIC - Institute of Optics |
Cristobal G.,CSIC - Institute of Optics |
Rodriguez P.,SENER Ingenieria y Sistemas |
Miravet C.,SENER Ingenieria y Sistemas |
Del Cura J.M.,SENER Ingenieria y Sistemas
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
This paper shows how local directional entropy can be used as a tool to build up a robust local image descriptor for image feature extraction. Among other possible choices, the Rényi entropy has been selected as the main technique for this application. Local directional entropy which is related with the anisotropy images has been considered here as the basis for the design of a new Rényi entropy-based local image descriptor (RELID). The properties of this new descriptor are described and evaluated. The experimental results confirm that the new descriptor is endowed by most of the invariant properties desired for object recognition applications. © 2010 SPIE.
Llorente J.S.,SENER Ingenieria y Sistemas |
Agenjo A.,SENER Ingenieria y Sistemas |
Carrascosa C.,GMV Inc |
De Negueruela C.,GMV Inc |
And 3 more authors.
Acta Astronautica | Year: 2013
Formation Flying (FF) has generated a strong interest in many space applications, most of them involving a significant complexity for building for example on-board large virtual structures or distributed observatories. The implementation of these complex formation flying missions with critical dependency on this new, advanced and critical formation technology requires a thorough verification of the system behaviour in order to provide enough guarantees for the target mission success. A significant number of conceptual or preliminary designs, analyses, simulations, and HW on-ground testing have been performed during the last years, but still the limitations of the ground verification determine that enough confidence of the behaviour of the formation flying mission will only be possible by demonstration in flight of the concept and the associated technologies. PROBA-3 is the mission under development at ESA for in-flight formation flying demonstration, dedicated to obtain that confidence and the necessary flight maturity level in the formation flying technologies for those future target missions. PROBA-3 will demonstrate technologies such as formation metrology sensors (from very coarse to highest accuracy), formation control and GNC, system operability, safety, etc. During the last years, PROBA-3 has evolved from the initial CDF study at ESA, to two parallel phase A studies, followed by a change in the industrial configuration for the Bridging step between A and B phases. Currently the SRR consolidation has been completed, and the project is in the middle of the phase B. After the phase A study SENER and GMV were responsible for the Formation Flying System, within a mission core team completed by OHB-Sweden, QinetiQ Space and CASA Espacio. In this paper an overview of the PROBA-3 mission is provided, with a more detailed description of the formation flying preliminary design and results. © 2012 Elsevier Ltd.
Rodriguez-Colina E.,Metropolitan Autonomous University |
Gil-Leyva D.,Sener Ingenieria y Sistemas |
Marzo J.L.,University of Girona |
Ramos R. V.M.,Metropolitan Autonomous University
Telecommunication Systems | Year: 2014
Inter-satellite links (ISL) are a useful technology to transmit data to space stations and to communicate between satellites. However, there are serious limitations due to long delays and poor channel performance, resulting in high bit error rates (BER). In this paper, parallel transmission and the scaling of the Transport Control Protocol (TCP) window in free space optics (FSO) communications are analyzed in order to overcome these disadvantages in optical inter-satellite links. Latency and BER are the dominant effects that determine link performance. Thus, a physical, link, network and transport cross-layer analysis for FSO over ISL is presented in this paper. This analysis shows the advantages and disadvantages of using optical parallel transmission and TCP window scaling for free space optical links between stations and satellite constellations. The key contribution of this work is to simulate the effects of the BER and to link the results to packet error rate (PER) to determine the goodput for TCP transmissions by using a cross-layering approach. The results give evidence that wavelength division multiplexing (WDM) can mitigate the effects of long delay and high BER for a FSO communication using TCP. © 2013 Springer Science+Business Media New York.