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Home>Products>Journal and Reviews>I.RE.AS.E.>Latest issue International Review of Aerospace Engineering - October 2008 - Papers
International Review of Aerospace Engineering - Papers
Abstract - The existence of types of mathematical models is conditioned by characteristics of the examined object. The process of synchronizing program modules employs this division in Information and Communication Technologies that are examined and optimized for the simulation process. The main problem in the process of synchronization is that how computing is done by the distributed control system – cluster or network. How can conditions of mathematical models be managed and how computing can become a creative and effective process. The physics of simulation model is well done and it is examined by their parameters easily. Now this model construction for some time is able to simulate the design of models very authentically. This work focuses on this very important field of science and technical community. The theory of design of decentralized computer control systems are derived from computers that create a distributed computer system of a flight simulator. Modelling of a time benefit of a simulator system is done by description using equations depending on architecture of computer systems. An important part of this article is the way of analysis types of mathematical models, a simulation method and an analytical approach, a corresponding calculation of a control implemented in single-processor architecture. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: admission job, cluster, mathematical model, task execution, parallel simulation.
Abstract - This paper address the problem of fault identification for Reusable Launch Vehicles (RLV) control surfaces. The identification scheme is based on a modified extended Kalman filter which not required derivatives, leading to an easy implementation at each updating time. A solution is provided for systematic tuning the filter noise covariance matrices. It is shown that this problem can be formulated as an optimization problem using a quadratic criterion which can be solved using a Particle Swarm Optimization (PSO) algorithm. A prior trimmability deficiency analysis procedure is also proposed using a state-space modeling approach. The simulation results are quite encouraging and suggest that the proposed fault identification scheme could be an efficient tool for advanced diagnosis algorithm for RLV actuators. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Nonlinear fault estimation, Atmospheric reentry, evolutionary optimization.
Abstract - This paper presents an overview of an on-going collaborative research project in Europe which gathers together the European Space Agency, University of Bordeaux (France) and Astrium Space Transportation. The project addresses the issue of on board fault tolerant path planning and robust fault diagnosis for next generation atmospheric reentry vehicles. The final aim is to promote innovative and robust technologies that could significantly increase spacecraft operational autonomy. The techniques are integrated in a supervisory layer which manages all or a part of the GNC chain during the reentry mission. Such a level of autonomy can be reached first by monitoring the vehicle behavior, then by reconfiguring all or a part of the G&C chain when a faulty scenario occurs. Some tools and techniques which are currently being developed to meet these objectives are presented here. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Reentry Vehicle, Fault Detection, Isolation and Reconfiguration, Replanning / Retargeting.
by D. M. Sharma, K. Poddar, A. Muthukumar, K.S.V. Reddy
Abstract -
Wind tunnel experiments were
carried out on NLF-0416 airfoil model to investigate the effect of
boundary Layer mixing devices on the aerodynamic characteristics and
hysteresis behavior associated with the pitching motion of the airfoil.
Pressure measurements were carried out on the mid span of the airfoil
and in the wake for quantitative information. The hysteresis behavior
was observed in aerodynamic characteristics as a function of pitch rates
and was found to increase with pitch rates. For the pitch rates covered
in the present study, no large eddy vortex formation associated with
deep dynamic stall was observed. The results show significant
improvements in hysteresis behavior and aerodynamic characteristics by
the application of boundary layer mixing devices. The data show that
placing the vortex generators between 5% and 7% of the chord which
corresponds to the approximate location of the pressure peak at lower
angles of attack, increases the lift coefficient and hysteresis lift
significantly while improving the drag characteristics. Vortex
generators close to the pressure peak allows the mixing of the outer
flow and boundary layer flow to occur before reaching adverse pressure
gradient. At low angle of attack region vortex generators completely
removes the hysteresis loops. In order to arrest the spanwise flow,
boundary layer fences were also used which resulted in improvement of
stall characteristics.
Keywords: Pitching airfoil, dynamic stall, hysteresis, flow control, vortex generator, boundary layer fence.
Abstract - There exists a growing use of Sigma-Point Kalman filters (SPKF) in fields where historically has dominated the Extended Kalman Filter (EKF). The SPKF are superiors to EKF in accuracy estimation and simplicity of implementation. However, their major drawback is due to the relatively poor execution speed compared with respect to the EKF. In order to reduce this problem, a new criterion for selecting a minimum set of sigma points has been proposed. This approach is known as Spherical Simplex Sigma-Points. Despite the relevance of achieving this goal for real-time applications, this approach is practically not discussed in literature. In this paper, we analyse the performance of two variants of classic SPKF with respect to two variants of Spherical Simplex Sigma-Points, all versions have been applied to the three-dimensional position estimation of a mini-helicopter. The results of the comparative analysis are shown through simulations. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inertial navigation, Mobile robots, Nonlinear filtering, Sigma-Point Kalman filters.
Abstract - In order to study the thermal behaviour of aeronautic stainless steel welded by TIG process, we have improved the energetic distribution formulation by adapting the geometric configuration into a bi-elliptic form with Gaussian surface heat flow distributions of the welding source. The Thermal transient fields and thermal cycles are evaluated to determine dimensions of the risky zones (Heat Affected Zone and Fusion Zone) and the welded joint is characterized by tension tests, micro-hardness (Hv) and micrographics. A metallographic analysis is prepared to differentiate all zones as well as the grain sizes, and to confirm theirs widths. Computations are carried out by finite volume method, where thermo-physic’s properties and boundary conditions are in function of temperature. The reliability of the model is evaluated by the comparison of the simulated results with those obtained by thermal cycle recordings to evaluate the size of the risky zones. Both, theoretical and experimental approaches have good agreement and give an enhancement of a previous work. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Aeronautic stainless steel, Mechanical and metallurgical characterization, TIG welding, Thermal simulation.
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