Time filter

Source Type

Coelho T.A.H.,University of Sao Paulo | Malvezzi F.,Maua Institute of Technology
Mechanisms and Machine Science | Year: 2015

The paper presents an asymmetric three-degree-of-freedom parallel mechanism purposely conceived as a robotic device for tool positioning applications. The kinematic structure of the mechanism contains one central passive limb that constrains the end-effector motion to two translations and one rotation. This work deals with important issues related to the parallel mechanism, such as the position kinematics analysis and the singular configurations prediction. © Springer International Publishing Switzerland 2015.

Romano R.A.,University of Sao Paulo | Romano R.A.,Maua Institute of Technology | Garcia C.,University of Sao Paulo
Journal of Process Control | Year: 2011

Among several process variability sources, valve friction and inadequate controller tuning are supposed to be two of the most prevalent. Friction quantification methods can be applied to the development of model-based compensators or to diagnose valves that need repair, whereas accurate process models can be used in controller retuning. This paper extends existing methods that jointly estimate the friction and process parameters, so that a nonlinear structure is adopted to represent the process model. The developed estimation algorithm is tested with three different data sources: a simulated first order plus dead time process, a hybrid setup (composed of a real valve and a simulated pH neutralization process) and from three industrial datasets corresponding to real control loops. The results demonstrate that the friction is accurately quantified, as well as "good" process models are estimated in several situations. Furthermore, when a nonlinear process model is considered, the proposed extension presents significant advantages: (i) greater accuracy for friction quantification and (ii) reasonable estimates of the nonlinear steady-state characteristics of the process. © 2010 Elsevier Ltd. All rights reserved.

Malvezzi F.,Maua Institute of Technology | Hess-Coelho T.A.,University of Sao Paulo
International Journal of Vehicle Systems Modelling and Testing | Year: 2015

This work deals with a three-degree-of-freedom mechanism for rear independent suspensions, capable to adjust simultaneously the camber, toe and roll angles. Topologically, the mechanism is parallel and asymmetric with three distinct active kinematic chains. In this paper, the kinematic and kinetostatic models are developed. In order to evaluate how promising this mechanism is, two analyses are conducted. First, a performance analysis evaluates the influence of the mechanism actuation on the vehicle dynamic behaviour and, second, a feasibility analysis determines a suitable stroke and the required force/power for the actuators. The obtained results have shown the capability of the mechanism to improve vehicle handling performance, when compared to a car equipped with a conventional suspension system. The evaluation is based on three manoeuvres: a steady-state cornering, a fishhook and a double lane change. Moreover, the mechanism feasibility analysis has shown that the actuator's stroke, velocity and force can be obtained by using standard hydraulic or eletromechanical actuators. Copyright © 2015 Inderscience Enterprises Ltd.

Alves V.A.O.,Maua Institute of Technology | Juliani Correa De Godoy R.,University of Sao Paulo | Garcia C.,University of Sao Paulo
Proceedings of the IEEE International Conference on Control Applications | Year: 2012

In some system identification methods, high order ARX models are adopted as true descriptions of the process to be identified. Afterwards, such high order model is used as a basis for a model order reduction procedure. The optimization strategy for the search of the best high order (in the fit index sense) for SISO ARX models, presented in a related paper [1], is extended to the MIMO case. The analyzed system is the Wood & Berry binary distillation column [2]. In this study, the search for the best dead times associated with the high order ARX model is also addressed. The results obtained by the optimization strategy are compared with those derived by exhaustive search. © 2012 IEEE.

Mockaitis G.,University of Sao Paulo | Rodrigues J.A.D.,Maua Institute of Technology | Foresti E.,University of Sao Paulo | Zaiat M.,University of Sao Paulo
Journal of Environmental Management | Year: 2012

Cadmium ion (Cd2+) toxicity on anaerobic systems, used for organic matter removal, was assessed by studying its effect on kinetic parameters and metabolic changes. This fundamental study was performed in a continuous fixed bed anaerobic bioreactor that treated synthetic wastewater simulating domestic sewage. The biomass was immobilized on a fixed bed made of polyurethane foam. Under influent cadmium concentrations of 0.0, 0.4, 4.4 and 6.2 mg Cd2+ L-1 the organic matter removal efficiencies were 84%, 82%, 72% and 52%, respectively. At influent concentration of 6.2 mg Cd2+ L-1 the reactor had reached its limit for cadmium toxicity. In the removal of dissolved organic matter, the first-order apparent kinetic coefficients (k1app) were 0.84, 0.67 and 0.10 h-1 for the operations with 0.0, 0.4 and 4.4 mg Cd2+ L-1, respectively. The apparent inhibition coefficient for cadmium (kiapp) was 1.69 mg L-1. Despite the toxic effects of cadmium on anaerobic organic matter removal at large Cd2+ concentrations, the results demonstrated that the anaerobic process was suitable for cadmium concentrations below 29.8 mg Cd2+ L-1, considering the bioavailable fraction of adsorbed cadmium in the support when the cadmium influent concentration was 6.2 mg Cd2+ L-1. © 2012 Elsevier Ltd.

Discover hidden collaborations