Papers by Ricardo Luiz Utsch de Freitas Pinto
Implementação do método de Multhopp para a previsão de estol em asas no regime subsônico
Proceedings of the XI Congresso Nacional de Engenharia Mecânica - CONEM 2022
Journal of Computational and Applied Mathematics, 1990
A method for the solution of systems of linear algebraic equations is presented. It is derived us... more A method for the solution of systems of linear algebraic equations is presented. It is derived using an approach based on linear estimation theory and is directly related to a generalization of Huang's method (1975) proposed by . Exploring the approach adopted, the paper presents properties complementary to those found in the literature. Among these is included a Potter's factorized form of the method. In terms of applications, the method is analyzed as an alternative tool to get pseudoinverses, the solution of a class of quadratic programming problems and of ill-conditioned linear systems where iterative schemes are necessary.
Active Noise Control for Small-Diameter Exhaustion System
Abstract. The active noise control system based on adaptive filter theory was developed in the 19... more Abstract. The active noise control system based on adaptive filter theory was developed in the 1980s. However, only with the recent introduction of powerful but inexpensive digital signal processor hardware has the technology become pratical. This work considers broadband feedforward ANC systems that have a reference sensor, single secondary source, and single error sensor. The main reason is related to the adaptation algorithms to the active noise control for small-diameter exhaust system. A modification of the well-known LMS algorithm, the filtered-X LMS algorithm, will be presented. Contrasts between passive and active noise control are decribed.
In this work high aspect-ratio straighttrapezoidal wing planforms are analyzed, considering both ... more In this work high aspect-ratio straighttrapezoidal wing planforms are analyzed, considering both aerodynamic and structural standpoints. The wings are analyzed as candidates to be used in a low-speed, very-low wing loading, solar aircraft. The motivation for the straighttrapezoidal wing planform geometry is to obtain a simple geometry to allow a feasible construction and installation of a solar array in its upper surface; and at the same time presenting low induced drag coefficient, in comparison with a rectangular wing of the same aspect ratio. The intermediate goals of the analysis are: In terms of aerodynamics, to obtain the trends of induced drag coefficient related to geometric proportions for a given aspect ratio; and in terms of structures, to define the trends of wing structural mass and wing main vibration modes, related to the variations on the wing geometry, for a given aircraft mass and design load factor. These intermediate features are the basis for the main goal to ob...
Abstract. This paper proposes a linear programming formulation for the Resource Constrained Proje... more Abstract. This paper proposes a linear programming formulation for the Resource Constrained Project Scheduling Problem (RCPSP) with processing time and amount of resource as continuous variables. The problem is modeled as a resources allocation problem combined with a scheduling activities problem, considering disjunctive graphs for the Job Shop. Moreover, precedence relations between the activities must be respected. The simultaneous allocation of renewable resources is modeled with the aid of binary variables. In this formulation, the processing time is a nonlinear function of the amount of resource allocated. Linear approximations using arbitrary set of line segments are used to reformulate the problem as a mixed linear programming problem. Although the treatment is initially aimed to continuous resources, it presents itself as an effective treatment for problems with discrete resources. The implementation of the proposed procedure is illustrated by a discrete example whose resou...
Hybrid approach to noise control of industrial exhaust systems
Applied Acoustics, 2017
Abstract This study aims to present a procedure for optimal design of hybrid noise control system... more Abstract This study aims to present a procedure for optimal design of hybrid noise control systems for exhaust ducts from large fans and high radiated sound power, in an industrial environment. Reactive, resistive or hybrid silencers are considered as alternatives with the possibility of adding a supplementary active noise control system to mitigate remaining noise of multiple low frequencies, which are difficult to be attenuated by passive means. Algorithms are proposed for the implementation of optimal hybrid passive/active design and the main theoretical and practical fundamentals involved are showed. Two effective solutions for a real industrial exhaust system are presented as examples of applications of hybrid optimal design procedure proposed. The first one uses of Helmholtz resonators (to attenuate lower frequencies) and resistive silencer parallel lamellae (to lower the midrange and high frequencies). The second one adopts resistive silencer of parallel lamellae and a forward active noise control system. This is a hybrid approach that is not treated in this manner in the available literature, especially in the text books of applied acoustics engineering.
arXiv: Numerical Analysis, 2018
In this paper we present a new family of rules for numerical integration. This family has up to h... more In this paper we present a new family of rules for numerical integration. This family has up to half the error of the widely used Newton-Cotes rules when a sufficient number of points is evaluated and also much better numerical stability for high orders. These rules can be written as the midpoint rule with a correction term, providing a straightforward and computationally cheap way to obtain error estimations. The rules are interpolatory and use evenly spaced points, which makes them well suited for many practical applications. Their major potential disadvantage is the use of points outside the integration interval.
Variação Na Capacidade De Carga De Elementos De Fundação Direta Considerando a Não Saturação De Um Solo Coluvionar Do Município De Belo Horizonte
Anais do XVIII Congresso Brasileiro de Mecânica dos Solos e Engenharia Geotécnica, 2015
Aerodynamic optimization of high aspect ratio wings for application in unmanned aerial vehicles (UAV's)
17th Brazilian Congress of Thermal Sciences and Engineering
Adaptation of a nonlinear lifting line based method into a vortex lattice code for stall and post stall calculation
Procceedings of the 24th ABCM International Congress of Mechanical Engineering
Design study of high aspect ratio wings for unmanned air vehicles (UAV's)
SAE Technical Paper Series
A revised theoretical analysis of aerodynamic optimization of horizontal-axis wind turbines based on BEM theory
Renewable Energy
Design of a High-Altitude Sun-Powered Aircraft
Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015
A Study About Canard Type Airplane Stability
Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015
Aircraft Configuration Improvement Study from Aerodynamic and Structure Standpoints
Applied Mechanics and Materials, 2015
In this work improvements on the geometry of a high aspect ratio aircraft wing are studied, in or... more In this work improvements on the geometry of a high aspect ratio aircraft wing are studied, in order to reduce the wing in-flight deformation, without changing the drag of the aircraft and without increasing the structural weight. For this, from a reference rectangular wing, one new wing with elliptical planform has been defined; and comparative analyses of loads and structural deformation have been made for the wings considered: the original rectangular wing and the new corresponding elliptical wing. The aerodynamic analysis is based on the lifting line approach. A computer routine is made by the authors based on this approach, to obtain both induced drag values and the load distribution of the two wings, the original one and the corresponding elliptical. Based on the loads, spars for the two wings have been defined, and in order to evaluate the vertical displacements in flight, a finite element routine have been used. The main result of this study is the comparison of the deformat...
An exact penalty function based on the projection matrix
Applied Mathematics and Computation, 2014
ABSTRACT This paper proposes an exact penalty function based on the projection matrix concept. Th... more ABSTRACT This paper proposes an exact penalty function based on the projection matrix concept. The proposed penalty function finds solutions which satisfy the necessary optimality conditions of the original problem. Some theoretical results are presented showing that every regular point provides an absolute minimum to the proposed penalty function if and only if it satisfies the necessary conditions of the original constrained problem. As a general rule, penalty functions may have spurious local minima. An advantage of the proposed penalty function is its ability to identify if an obtained minimum is spurious. The proposed penalty function was applied to solve equality constrained problems from the Hock–Schittkowski Collection. Some solutions were obtained more efficiently using the new penalty function than by using a conventional constrained optimization method.
SAE Technical Paper Series, 2004
This paper present the instrumentation procedure used in order to determine the performance, stab... more This paper present the instrumentation procedure used in order to determine the performance, stability and control characteristics of the light aircraft CEA-205 CB-9 Curumim. The instrumentation used is: i) autonomous acquisition system using micro controllers; ii) solid state inertial platform; iii) pitot probe ; iv) attack and sideslip angle indicators; v) potentiometer on command system; vi) load cell on command system; vii) propeller tachometer; viii) barometer; ix) thermometer and x) GPS. Assembly and calibration detail procedures are presented with some results obtained on typical maneuvers. This work, in development on the Center for Aeronautical Studies of Federal University of Minas Gerais (UFMG) and on the University of Naples, intend to assembly a system in order to perform low cost flight tests on light aircrafts.
Sub-optimal control laws for minimization of take-off distance for aircrafts
SAE Technical Paper Series, 2006
Abstract The present paper presents a method for the numerical determination of control laws for ... more Abstract The present paper presents a method for the numerical determination of control laws for aircrafts needed for optimization of a pre-established maneuver, applied to a take-off under requirements of FAR-Part 23. The methodology is based on the minimization of ...
Mathematical Modeling for Optimization of Competition Sailplane Flight: a Preliminary Approach
SAE Technical Paper Series, 2003
ABSTRACT In this work, sailplane symmetrical motion equations including pitch motion controlled b... more ABSTRACT In this work, sailplane symmetrical motion equations including pitch motion controlled by elevator angle are presented. The following effects are especially taken into consideration: i) tail damping due to pitch motion; ii) air density variation according to ...
Flight Path Optimization for Competition Sailplanes through State Variables Parameterization
SAE Technical Paper Series, 2004
Abstract. This paper presents a numerical process for determination of optimal flight paths for c... more Abstract. This paper presents a numerical process for determination of optimal flight paths for competition soaring. The issue is reduction of flight time in order to soar towards an ascending thermal and climb, through thermal flying, to the initial altitude. The optimization ...
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Papers by Ricardo Luiz Utsch de Freitas Pinto