Brazil offers significant potential for installing floating photovoltaic systems in artificial reservoirs, as it represents the world's second-largest installed hydroelectric capacity, corresponding to 56.8% of the Brazilian electrical energy matrix. The current paper highlights the potential contributions of floating photovoltaic solar energy to the Brazilian renewable energy matrix, specifically regarding land use efficiency and water resource management. In addition, through a comparative analysis with a global scenario, this work shows the importance of Brazil's water bodies and sunlight for renewable energy generation. It shows that using 1% of surface areas in artificial water bodies in Brazil can generate 57,384 GWh/year, reaching up to 5 times the generation capacity, as indicated by more recent studies. Moreover, analyzing data for one-day hourly generation considering a hybrid system would result in an increase of approximately 4% in electricity generation. By leveraging its favorable conditions and addressing the challenges, Brazil has the opportunity to establish itself as a pioneer in the (FPV) sector, contributing to its sustainable energy future and the global transition to renewable sources.

A simple loop shaping technique is applied to design an optimal, robust feedback controller to reduce the interior noise of an acoustic cavity. It is a data-based technique that uses the measured plant response to tune the parameters of a fixed-structure controller in a graphical way. The two cases studied are narrowband noise control in a small cavity and broadband noise control in a long duct. Each control system consists of a microphone, a loudspeaker, and a controller connecting the two transducers that are further collocated. The fixed-structure of each controller should be chosen ahead of loop shaping and is determined in this paper solely based on the Nyquist plot of each plant measured. It turns out that a single band (high) pass filter of second order is suitable for the narrowband (broadband) noise control case considered. It is finally demonstrated with experiments that the technique is practical and a second order filter can be effectively used for active control of cavity noise in a single narrow or broad frequency band.

Electromechanical impedance-based (EMI) damage detection techniques are based on the capability of piezoelectric materials to act as sensors and actuators and they have contributed to the development of structural health monitoring (SHM) systems. Classic techniques use a PZT (Pb-lead Zirconate Titanite) transducer attached to the monitored structure and measure the impedance signature of the couple PZT-Structure. However, EMI based techniques are depending of different factors such as frequency range, number of PZT, ambient temperature, type of structure, among others. Thus, in order to demonstrate the effectiveness of EMI-based methods, it is necessary to carry out practical experiments, which is not a trivial task when such factors have to be considered. Therefore, in this paper, it is presented an EMI-based finite element (FE) model developed using PZFlex® software, which is based on FE. Two different structures were simulated and evaluated: a rectangular aluminum plate and a steel pipe. Simulated results were compared with practical ones and show that the proposed model can be a powerful tool for developing EMI-based SHM techniques.

This paper describes a theoretical and experimental investigation into an electrical Helmholtz resonator (EHR): that is, an active noise control (ANC) loudspeaker used in conjunction with a microphone and a feedback controller for suppressing resonant noise in an acoustic cavity. The microphone is collocated with the loudspeaker and a band pass filter of second-order is used as the control filter inside the controller. The EHR is configured as such in order to suppress an acoustic mode that is within the volume velocity drive frequency range of the loudspeaker used. The concepts of impedance and passivity are used to develop the mathematical model as well as to study its dynamics. From these, it is theoretically shown that the EHR for single-mode suppression is an extremely low-impedance acoustic damping device that electrically realizes the pressure neutralization mechanism of a conventional Helmholtz resonator (HR). Experimental work is also presented, in which an EHR is constructed to suppress the Helmholtz mode of an acoustic cavity at about 40 Hz by more than 40 dB, to justify the mathematical model and also to verify the dynamic control mechanism.

This paper presents a methodology to perform the monitoring and identification of flaws in aircraft structures using an ARTMAP-Fuzzy-Wavelet artificial neural network. This technique is used in the detection and characterization of structural failure. The main application of this method is to assist in the inspection of aircraft structures in order to identify and characterize failures as well as decision-making, in order to avoid accidents or air crashes. In order to evaluate this method, the modeling and simulation of signals from a numerical model of an aluminum beam was performed. The results obtained by the method are satisfactory compared to literature.

This paper presents an ARTMAP-Fuzzy-Wavelet artificial neural network to perform the analysis of the structural integrity of a building. The combination of Fuzzy ARTMAP neural network, wavelets transform to generate a tool that performs the identification and characterization of structural failure. This method is applied as a support tool for professionals in the inspection of mechanical and building structures to identify and characterize flaws in order to carry out preventive maintenance to ensure the integrity of the structure and decision making. In order to validate the methodology perform mathematical modeling of a building of two walk, and from this model were simulated different situations (base-line condition and improper conditions), yielding a database of signals that serve as input ARTMAP-Fuzzy-Wavelet neural network. The results obtained by ARTMAP-Fuzzy-Wavelet shown efficiency and robustness.

This paper presents a noncontact technique for displacement measurement based on the variation of the pixels positions of a target object in the images captured by CCD or CMOS sensor. A video from a moving structure is made and then it is analyzed frame by frame and the variation of the pixels position of the target object in the structure is calculated for each frame and related with the position of the object in the image. The proposed approach is evaluated to measuring vibrations of a reduced scale model of two-floor building lab structure, which focuses on the advantage of using a unique camera for measurements of structural vibrations. The results obtained are compared to reference model and have shown good agreement.

Este trabalho consiste em investigar técnicas de monitoramento de integridade estrutural baseadas em Índices de Falha para detectar danos estruturais. Inúmeros problemas estruturais intensamente noticiados pela mídia, alguns resultando em vítimas fatais, demonstram a importância de se desenvolver metodologias confiáveis de monitoramento da integridade estrutural a fim de evitar catástrofes que resultem em perdas de vidas humanas, danos ao meio ambiente ou prejuízos financeiros. Trata-se, portanto, de um tema atual e de grande interesse tecnológico, em virtude das questões econômicas e de segurança. Em particular, o trabalho consiste em estudar, implementar e aplicar uma metodologia de monitoramento da condição estrutural (do inglês Structural Health Monitoring, SHM) baseado em medidas da norma H2, RMSD (Root-Means-Square Deviation), IFM (Índice de Falha Métrica) e CCDM (Correlation Coefficient Deviation). A metodologia é baseada no cálculo de uma das normas para a estrutura com e sem falha e na avaliação da diferença entre elas. Assim, o dano estrutural é detectado.

The electromechanical impedance (EMI) technique has been successfully used in structural health monitoring (SHM) systems on a wide variety of structures. The basic concept of this technique is to monitor the structural integrity by exciting and sensing a piezoelectric transducer, usually a lead zirconate titanate (PZT) wafer bonded to the structure to be monitored and excited in a suitable frequency range. Because of the piezoelectric effect, there is a relationship between the mechanical impedance of the host structure, which is directly related to its integrity, and the electrical impedance of the PZT transducer, obtained by a ratio between the excitation and the sensing signals.This work presents a study on damage (leaks) detection using EMI based method. Tests were carried out in a rig water system built in a Hydraulic Laboratory for different leaks conditions in a metallic pipeline. Also, it was evaluated the influence of the PZT position bonded to the pipeline. The results show that leaks can effectively be detected using common metrics for damage detection such as RMSD and CCDM. Further, it was observed that the position of the PZT bonded to the pipes is an important variable and has to be controlled.

A técnica da impedância eletromecânica (EMI) é utilizada de maneira eficiente em sistemas de monitoramento de integridade estrutural (SHM) para uma grande variedade de estruturas, esta técnica faz o monitoramento mediante a excitação e detecção de um transdutor piezelétrico. Neste trabalho são monitoradas duas estruturas com a técnica da EMI, a primeira é um tubo de aço e a segunda é uma tubulação com fluxo constante de água. Foram analisados os efeitos do posicionamento do transdutor na estrutura e a frequência de excitação mais adequada para maior sensibilidade ao dano.

O uso de materiais piezelétricos na conversão de energia mecânica, proveniente das vibrações, em energia elétrica tem aumentado consideravelmente nos últimos anos principalmente devido a alta capacidade de conversão de energia desses materiais. Entretanto, grande parte dos trabalhos mostrados na literatura apresentam dispositivos e estruturas piezelétricas de energy harvesting que atende os requisitos de geração e armazenamento de energia apenas quando operam na ressonância, quando operam em condições de excitação ligeiramente diferentes da ressonância a energia elétrica convertida diminui drasticamente. O presente trabalho apresenta a configuração de uma estrutura piezelétrica denominada piezoestrutura multifrequência que possibilita a geração de energia em uma quantidade razoável mesmo quando ocorrem variações nas condições de operação da estrutura. O comportamento da piezoestrutura multifrequência é obtido através de simulações no software ANSYS e a banda de frequência de operação é definida utilizando o conceito de banda de meia potência. Os resultados numéricos do modelo são comparados com dados experimentais mostrando sua potencialidade de aplicação.

In this paper we present a versatile and easy-to-assemble measurement system for structural health monitoring (SHM) based on the electromechanical impedance (EMI) technique. The hardware of the proposed system consists only of a common data acquisition (DAQ) device with external resistors and allows real-time data acquisition from multiple sensors. Besides the low-cost compared to conventional impedance analyzers, the hardware and the software are simple and easier to implement than other measurement systems that have been recently proposed.

The structural health monitoring (SHM) systems based on electromechanical (E/M) impedance technique have been widely investigated. Although many studies indicate the reliability of this technique, some practical considerations still have to be considered in real applications. This paper presents an experimental analysis of the effect of the structure area on the system's performance. The results indicate that the sensitivity of the system to detect damage decreases significantly when the host structure has large cross-section area.

This paper presents two different approaches to detect, locate, and characterize structural damage. Both techniques utilize electrical impedance in a first stage to locate the damaged area. In the second stage, to quantify the damage severity, one can use neural network, or optimization technique. The electrical impedance-based, which utilizes the electromechanical coupling property of piezoelectric materials, has shown engineering feasibility in a variety of practical field applications. Relying on high frequency structural excitations, this technique is very sensitive to minor structural changes in the near field of the piezoelectric sensors, and therefore, it is able to detect the damage in its early stage. Optimization approaches must be used for the case where a good condensed model is known, while neural network can be also used to estimate the nature of damage without prior knowledge of the model of the structure. The paper concludes with an experimental example in a welded cubic aluminum structure, in order to verify the performance of these two proposed methodologies.

Vibration monitoring of components in manufacturing plants involves the collection of vibration data, and a detailed analysis of data. One of the most important characteristic of neural networks is their ability to model process and systems from actual data, and to respond in real time to the changes in the machine state. This paper discusses the use of neural network for fault classification in rotating systems using signal of vibration.