Aeronautics Institute of Technology ITA

Brazil

Aeronautics Institute of Technology ITA

Brazil
SEARCH FILTERS
Time filter
Source Type

De Castro P.A.L.,Aeronautics Institute of Technology ITA | Annoni R.,Raifa Intelligent Systems
FTC 2016 - Proceedings of Future Technologies Conference | Year: 2016

Since early days of computer science, researchers ask themselves where is the line that separates tasks machine can do from those only human beings can really accomplish. Several tasks were pointed as impossible to machines and later conquered by new advances in Artificial Intelligence. Nowadays, it seems we are not far from the day when driving cars will be included among the tasks machines can do in an efficient way. Certainly, even more complex activities will be dominated by machines in the future. In this paper, we argue that investment analysis, the process of assessment and selection of investments in terms of risk and return, should and can be among the tasks performed efficiently by machines in the (maybe not so far) future. Investment decisions have to be faced not only by financial professionals but by all people. Naturally, these professionals have more complex and often decisions to make, but everybody needs to invest to warrant good standard of living in the old age. In fact, there is significant research effort to create algorithms and/or quantitative methods to analyze investments. We present a brief review of them. Through this review, we may realize that there are many interconnected challenges in the quest for autonomous investment analysis. In this paper, we propose an adaptive multiagent architecture that deals with these three dimensions of complexity (nature of assets, multiple analysis algorithms per asset and horizon of investment) and keeps an explicit model of investor's preferences. This architecture breaks down the complexity faced by AIA in problems that can be addressed by a group of agents that work together to provide intelligent and customized investment advices for individuals. We believe that such architecture may contribute to development of AIA that deals with the complexity of the problem in a tractable way. Furthermore, this architecture allows the incorporation of known algorithms and techniques that may help to solve part of the issue. © 2016 IEEE.


Ballesteros H.M.S.,Embraer SA | Das Neves Calvo R.,Embraer SA | Filho A.A.,Aeronautics Institute of Technology ITA
Proceedings - 2017 IEEE International Conference on Mechatronics, ICM 2017 | Year: 2017

In flight control systems, electro-hydraulic actuators are responsible for moving the aircraft primary control surfaces under boundary conditions defined by time and frequency response requirements and at the same time preventing control surface flutter when mass balancing strategies are not feasible. The flutter prevention is translated into a set of dynamic stiffness and dynamic damping requirements [1] for the hydraulic actuator. This work aims to investigate different actuator's position control strategies seeking compliance with performance requirements while enhancing the actuator's dynamic stiffness. Actuator performance is evaluated for classic controllers and a modern control approaches using an LQR control strategy and a linear reduced-order observer. This work will show the benefits of applying modern control techniques that contribute to an increase in the actuator dynamic stiffness. © 2017 IEEE.


dos Santos C.R.,University of Sao Paulo | Pereira D.A.,Aeronautics Institute of Technology ITA | Marques F.D.,University of Sao Paulo
Journal of Fluids and Structures | Year: 2017

Helicopter blades and wind turbines are examples of aeroelastic systems that can reach high angles of attack and can vibrate due to the effects of the dynamic stall, thereby leading to fatigue problems or performance loss. Structural and aerodynamic nonlinearities influence the aforementioned behavior and their modeling is crucial for phenomena characterization. Such system modeling requires proper knowledge of the physical events during the stall, which can be better achieved by validating the model with experimental data. This work investigates the nonlinear dynamics of a NACA 0012 airfoil under the influence of structural and aerodynamic nonlinearities due to dynamic stall effects at high angles of attack. Experimental and numerical analyses are carried out. Moreover, different preset incidence angles for the typical aeroelastic section are also considered. The aeroelastic signals are used for estimating the Hopf bifurcation onset and to build the bifurcation diagrams. By using a typical section model with two degrees of freedom coupled to the Beddoes–Leishman aerodynamic model, numerical results have been able to capture with good precision experimental features. The onset of the Hopf bifurcations allows the determination of the flutter critical airspeed. Results for zero preset angle show that limit cycle oscillations from small to moderate displacements are mostly driven by the hardening nonlinearity. After reaching larger angles of incidence the dynamic stall nonlinearities supplant those from structural sources. For higher preset angles, the dynamic stall effects tend to increase the energy associated with pitching motion and to reduce amplitudes in plunge motion. Another effect related to the aerodynamic nonlinearities relies on the increase of the flutter velocity by around 10% for preset angles ranging from zero up to ten degrees. For higher preset angles an abrupt reduction in the flutter onset velocity is observed. © 2017 Elsevier Ltd


Martos J.F.A.,Aeronautics Institute of Technology ITA | Rego I.S.,Institute Estudos Avancados IEAv | Toro P.G.P.,Institute Estudos Avancados IEAv
21st AIAA International Space Planes and Hypersonics Technologies Conference, Hypersonics 2017 | Year: 2017

Nowadays, scramjet is a topic that has attracted the attention of several scientific communities (USA, Australia, Germany, France, Japan, India, China, Russia), that are investing in this in this type of propulsion system due its interest to facilitate access to space and reach hypersonic speed. The Hypersonic Brazilian Aerospace Vehicle 14 – X B is a technological demonstrator of hypersonic propulsion system technology based on supersonic combustion (scramjet) designed to fly in Earth’s atmosphere at 30 km altitude and the speed to Mach number 7. The development of a technological scramjet demonstrator must integrate theoretical and analytical analysis, numerical simulation and experimental research in hypersonic shock tunnel. A 1-m long stainless steel 14-X B model was experimentally investigated at T3 Hypersonic Shock Tunnel, for freestream Mach number 7. Experimental data was compared to the analytical theoretical solutions and the computational fluid dynamics (CFD) simulations, showing good qualitative agreement, and in consequence demonstrating the importance of these methods in the project of the 14-X B hypersonic scramjet aerospace vehicle. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.


de Medeiros-Junior R.A.,Aeronautics Institute of Technology ITA | de Lima M.G.,Aeronautics Institute of Technology ITA | de Medeiros M.H.F.,Polytechnic University of Mozambique
Environment, Development and Sustainability | Year: 2015

Chloride is one of the main factors responsible for damages related to the corrosion of the concrete reinforcement in marine environments. It is known that this mechanism of degradation is directly related to environmental variables. Within this context, it can be inserted the global climate change. This paper deals with the effects of temperature and relative humidity changes on the service life of concrete structures affected by chloride attack. This way, three situations of environmental aggressiveness were simulated: past, current, and future. Then, models for predicting the chlorides penetration were analyzed to the three selected situations. So, a practical methodology is presented, and the results are consistent with the literature data. Among the results, it can be noted that changes in temperature and relative humidity identified in a period of 100 years were responsible for a reduction from 7.8 to 10.2 years of service life. Most standards provide a design service life of 50 years for reinforced concrete structures. © 2014, Springer Science+Business Media Dordrecht.


Silveira F.F.,Federal University of São Paulo | Da Cunha A.M.,Aeronautics Institute of Technology ITA | Lisboa M.L.,Federal University of Rio Grande do Sul
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

Aspect-Oriented Software Development is a contemporary technique of software development that aims to improve the separation of concerns issues faced by traditional approaches. It improves the modularity of crosscutting concerns into units called aspects. However, this feature raises concerns about the quality of aspect-oriented programs (AOP). Existing functional testing approaches do not directly investigate the aspect composition problem, its resultant interactions and representation on a dynamic model. This paper describes a state-based testing method for AOP that targets class-aspect and aspect-aspect faults. To support the developed method, we introduce a model to represent the dynamic behavior of aspects interactions, a strategy to derive testing sequences, and a testing tool. Results of our assessment show that the approach is capable of detecting faults based on fault-models available in the literature. Furthermore, it is able to reveal another source of faults on AOPs, the aspect composition fault. © 2014 Springer International Publishing.


Panasiewicz J.,National Institute for Space Research | Pacheco G.M.,Aeronautics Institute of Technology ITA
SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings | Year: 2015

This article presents a photonic circuit that achieves direct carrier BPSK modulation of a RF signal from an opto-electronic oscillator suitable for satellite telemetry and control. The circuit was implemented with two Mach-Zehnder optical modulators. The optical wavelength is 1550 nm. One modulator was used to construct an optoelectronic oscillator to generate a carrier with frequency equal to 2.5 GHz. The second modulator was used to perform the BPSK direct modulation of the carrier signal. A bit rate of 1 Mbps was used and an EVM of 9.6% was obtained. The diagrams of the optoelectronic circuits and the modulation measurements are displayed. © 2015 IEEE.


Da Silva Jacinto A.,Aeronautics Institute of Technology ITA | De Oliveira J.M.P.,Aeronautics Institute of Technology ITA
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering | Year: 2012

Problem solving requires a lot of work for selecting and organizing resources and information, as well as defining the best solution approaches. In the case of ill-structured problems (ISP), due to the possibility of several potential solutions, the task becomes harder. Group work can better support this task but requires cognitive tools in order to allow the registration and the recovery of data about the problem and the exchange of ideas. This paper presents a process to support solving ISP, using ontology and software tools in order to facilitate the group work. Preliminary experiments indicate the feasibility of the process. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.


Scatolini F.,Aeronautics Institute of Technology ITA | Alves C.J.P.,Aeronautics Institute of Technology ITA | Eller R.D.A.G.,Aeronautics Institute of Technology ITA
Applied Acoustics | Year: 2016

This paper presents the difficulties found in trying to apply the "Balanced Approach" concept of ICAO (UN-International Civil Aviation Organization) on the noise pollution mitigation at urban Brazilian airports using, as a case study, the Congonhas Airport. It has been discussed by means of alternative operating scenarios, how to make the concept more flexible, aiming to bring the benefit of any additional acoustic comfort, without diminishing the installed capacity and already limited for environmental reasons. The results show that there are conditions for improvement, since there are both awareness of all players involved and permanent and real-time noise monitoring, even if those mitigating measures are not reflected on the noise annoyance models currently adopted for the land use planning. © 2015 Elsevier Ltd. All rights reserved.


Alves A.D.,Aeronautics Institute of Technology ITA | Yanasse H.H.,Federal University of São Paulo | Soma N.Y.,Aeronautics Institute of Technology ITA
Scientometrics | Year: 2016

Journal Citation Reports (JCR) is the main source of bibliometric indicators known by the scientific community. This paper presents the results of a study of the distributions of the first and second significant digits according to Benford’s law (BL) of the number of articles, citations, impact factors, half-life and immediacy index bibliometric indicators in journals indexed in the JCR Sciences and Social Sciences Editions from 2007 to 2014. We also performed the data analysis to country’s origin and by journal’s category, and we verified that the second digit has a better adherence to BL. The use of the second digit is important since it provides a more sound, complete and consistent analysis of the bibliometric indicators. © 2016 The Author(s)

Loading Aeronautics Institute of Technology ITA collaborators
Loading Aeronautics Institute of Technology ITA collaborators