Desenvolvimento e avaliação de pulverizador florestal com detecção eletrônica de plantas daninhas e aplicação em doses variáveis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Real-time multi-sensors measurement system with temperature effects compensation for impedance-based structural health monitoring

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

An electrochemical sensor for (L)-dopa based on oxovanadium-salen thin film electrode applied flow injection system

An oxovanadium-salen complex (NAP-ethylene-bis(salicylidenciminato) oxovanadium) thin film deposited on a graphite-polyurethane electrode was investigated with regard to its potential use for detection of L-dopa in flow injection system. The oxovanadium(IV)/oxovanadium(V) redox couple of the modified electrode was found to mediate the L-dopa oxidation before its use in the FIA system. Experimental parameters, such as pH of the carrier solution, flow rate, sample volume injection and probable interferents were investigated. Under the optimized FIA conditions, the amperometric signal was linearly dependent on the L-dopa concentration over the range 1.0 x 10(-1) to 1.0 x 10(-4) mol L-1 (I-anodic, mu A) = 0.01 + 0.25 [L-dopa mu mol L-1]) with a detection limit (S/N = 3) of 8.0 x 10(-7) mol L-1 and a sampling frequency of 90 h(-1) was achieved. For a concentration of 1.0 x 10(-5) mol L-1 L-dopa, the R.S.D. of nine consecutive measurements was 3.7%. (c) 2006 Elsevier B.V. All rights reserved.

Combining SERRS and electrochemistry to characterize sensors based on biomembrane mimetic models formed by phospholipids

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Toward the Optimization of an e-Tongue System Using Information Visualization: A Case Study with Perylene Tetracarboxylic Derivative Films in the Sensing Units

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A New Impedance Measurement System for PZT-Based Structural Health Monitoring

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modified LPE system used to diffuse Cd to obtain InSb infrared detectors

We are presenting here p/n junctions obtained with a modified opened liquid-phase epitaxy (LPE) system, used to diffuse indium antimonide (InSb) doped with Cd over InSb doped with Te wafers, in order to make InSb infrared (IR) sensors. This technique has several advantages: the diffusion can be performed in bigger substrate areas improving the device production; this method decreases the device manipulation, decreasing human mistakes and increasing the process reproducibility. The opened LPE in this work produced sensors in the first case with vapor of the diffusion material, coming from a microholed carbon boat full of the diffusion material, over which is positioned the substrate at atmospheric pressure. In the second, the diffusion material is on the bottom of a quartz recipient, and the InSb/Te wafer works as its cover, and vacuum was used. The IR sensors produced with the first method measured 8.9 x 10(7) cm Hz(1/2)/W as detectivity value and higher IR spectral response at 4.6 mu m, and those produced with the second 2.8 x 10(9) cm Hz(1/2)/W, at 4.4 mu m. Besides the electrical-optical properties, the structural properties of diffused layers were investigated by X-ray diffraction (XRD), scanning electron and atomic force microscopy (SEM, AFM), energy-dispersive and secondary ion mass spectroscopy (EDS, SIMS). (C) 2007 Elsevier B.V. All rights reserved.

Automatic dimming multi-lamp fluorescent management system with active input power factor corrector stage

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Design of a control system using linear matrix inequalities for the active vibration control of a plate

The study of algorithms for active vibration control in smart structures is an area of interest, mainly due to the demand for better performance of mechanical systems, such as aircraft and aerospace structures. Smart structures, formed using actuators and sensors, can improve the dynamic performance with the application of several kinds of controllers. This article describes the application of a technique based on linear matrix inequalities (LMI) to design an active control system. The positioning of the actuators, the design of a robust state feedback controller and the design of an observer are all achieved using LMI. The following are considered in the controller design: limited actuator input, bounded output (energy) and robustness to parametric uncertainties. Active vibration control of a flat plate is chosen as an application example. The model is identified using experimental data by an eigensystem realization algorithm (ERA) and the placement of the two piezoelectric actuators and single sensor is determined using a finite element model (FEM) and an optimization procedure. A robust controller for active damping is designed using an LMI framework, and a reduced model with observation and control spillover effects is implemented using a computer. The simulation results demonstrate the efficacy of the approach, and show that the control system increases the damping in some of the modes.

Experimental Active Vibration Control in Truss Structures Considering Uncertainties in System Parameters

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Magnetoresistive sensors in a new biomagnetic instrumentation for applications in gastroenterology

Anisotropic Magnetoresistive (AMR) sensors shows a new possibility to detect magnetic fields produced by magnetic particles present in the gastrointestinal (GI) tract. A system that uses excitation and detection of magnetic field was developed using AMR sensor. A magnetic flux concentrator was also studied to increase the sensitivity of AMR in this work.

Variable dose rate application of herbicides using optical sensors

The aim of this study was to develop and evaluate a variable dose rate application of herbicides using an online electronic control based system with optical sensors for weed detection in forested areas. The proposed concept was to apply a basic dose on 100% of the area (aiming to control small weeds) and to apply a complementary patch-spraying dose only on areas with higher weed infestation. For that purpose, a conventional spray boom was adjusted to apply 40% of the herbicide dose on the full area and the optical sensors were used to control the application of the complementary dose (60%) only on areas with higher infestation. The results showed that the system performed adequately. Field applications presented herbicide savings around 20 to 30%, with a similar weed control performance as compared to the full dose application on 100% of the area.

Development of a low-cost mobile mapping system: A South American experience

This paper presents the prototype of a low-cost terrestrial mobile mapping system (MMS) composed of a van, two digital video cameras, two GPS receivers, a notebook computer, and a sound frame synchronisation system. The imaging sensors are mounted as a stereo video camera on top of the vehicle together with the GPS antennae. The GPS receivers and the notebook computer are configured to record data referred to the vehicle position at a planned time interval. This position is subsequently transferred to the road images. This set of equipment and methods provide the opportunity to merge distinct techniques to make topographic maps and also to build georeferenced road image databases. Both vector maps and raster image databases, when integrated appropriately, can give spatial researchers and engineers a new technique whose application may realise better planning and analysis related to the road environment. The experimental results proved that the MMS developed at the São Paulo State University is an effective approach to inspecting road pavements, to map road marks and traffic signs, electric power poles, telephone booths, drain pipes, and many other applications important to people's safety and welfare. A small number of wad images have already been captured by the prototype as a consequence of its application in distinct projects. An efficient organisation of those images and the prompt access to them justify the need for building a georeferenced image database. By expanding it, both at the hardware and software levels, it is possible for engineers to analyse the entire road environment on their office computers.

Optimal placement of sensors/actuators in truss structures with known disturbances

An important stage in the solution of active vibration control in flexible structures is the optimal placement of sensors and actuators. In many works, the positioning of these devices in systems governed for parameter distributed is, mainly, based, in controllability approach or criteria of performance. The positions that enhance such parameters are considered optimal. These techniques do not take in account the space variation of disturbances. An way to enhance the robustness of the control design would be to locate the actuators considering the space distribution of the worst case of disturbances. This paper is addressed to include in the formulation of problem of optimal location of sensors and piezoelectric actuators the effect of external disturbances. The paper concludes with a numerical simulation in a truss structure considering that the disturbance is applied in a known point a priori. As objective function the C norm system is used. The LQR (Linear Quadratic Regulator) controller was used to quantify performance of different sensors/actuators configurations.

Experimental damage detection using system norms

Nowadays there is great interest in structural damage detection in systems using nondestructive tests. Once the failure is detected, as for instance a crack, it is possible to take providences. There are several different approaches that can be used to obtain information about the existence, location and extension of the fault in the system by non-destructive tests. Among these methodologies, one can mention different optimization techniques, as for instance classical methods, genetic algorithms, neural networks, etc. Most of these techniques, which are based on element-byelement adjustments of a finite element (FE) model, take advantage of the dynamic behavior of the model. However, in practical situations, usually, is almost impossible to obtain an accuracy model. In this paper, it is proposed an experimental technique for damage location. This technique is based on H: norm to obtain the damage location. The dynamic properties of the structure were identified using experimental data by eigensystem realization algorithm (ERA). The experimental test was carried out in a beam structure through varying the mass of an element. For the output signal was used a piezoelectric sensor. The signal of input of sine form was generated through SignalCalc® software.