Publicações - engenharias
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RIBEIRO, KEVIN MAURICIO MENON;
AMARAL, GABRIEL RUGGIERO DO;
BALTHAZAR, JOSÉ MANOEL;
WAHRHAFTIG, ALEXANDRE DE MACÊDO;
Eduardo Márcio de Oliveira Lopes
Palavra-chave:
Bending stiffness;
Material loss factor;
Nonlinear optimization techniques;
Overhead power cables;
Parametric idenfification;
Receptance equation
Áreas do conhecimento:
Engenharias; Engenharia Mecânica; Mecânica dos Sólidos; Dinâmica dos Corpos Rígidos, Elásticos e Plásticos
resumo ...
Wind-induced vibrations pose a significant global challenge in the electric power transmission sector. The alternating shedding of Von Kármán vortices, resulting from airflow around overhead power cables, induces oscillations that can lead to cable failure due to fatigue, if they are not properly understood and controlled. In this context, it is of special concern the ability to predict the dynamic behavior of these cables, which are systems with high modal density. This study presents an improved and integrated experimental/numerical method to identify elastic and dissipative parameters of overhead power cables, using a novel receptance expression, experimental data and nonlinear optimization techniques. The receptance expression (which relates displacement and force in the frequency domain) is of analytical nature, the fidelity of which is verified in comparison to a formulation developed via the finite element method. Experimental data are collected from discrete harmonic sweep and impact tests, performed on a conductor cable in a laboratory bench under five different tensile loads. The ensuing results show that the bending stiffness tends to increase with tensile load while the equivalent material loss factor tends to decrease, which is consistent with reports in the pertinent literature. It is shown that the proposed method proves to be a consistent, efficacious and meaningful alternative for thesimultaneous and flexible estimation of stiffness and damping parameters of overhead power cables, contributing to advance the subject beyond its current state.
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VALDÉS, A.C.;
DE SOUZA, D.J.;
CAPRARO, A.P.B.;
Ricardo Pieralisi;
Marcelo Henrique Farias de Medeiros
Palavra-chave:
Internal sulfate attack;
expansão do concreto;
reações expansivas;
Durabilidade
Áreas do conhecimento:
Engenharias; Engenharia Civil; Inovação
resumo ...
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José João de Espíndola;
José João de Espíndola;
José João de Espíndola
Palavra-chave:
Viscoelastic Support;
Passive Control of Structures;
Rotordynamic;
Optimum Design;
Experimental Study
Áreas do conhecimento:
Engenharias; Engenharia Mecânica; Mecânica dos Sólidos; Vibrações
resumo ...
The growing demand for enhanced energy efficiency in the industrial sector necessitates increasingly precise analyses of rotor dynamics and, in many cases, the implementation of vibration control systems to maintain acceptable vibration levels in rotating machinery. This paper presents numerical and experimental studies to address the challenges limiting the widespread application of viscoelastic supports (VES) by proposing a constructively simple and optimally designed VES that delivers high static stiffness while effectively reducing unbalance response. A finite element model of the rotating system was developed, and parametric optimization techniques were employed to design the viscoelastic support for maximum reduction of the system’s unbalance response. The feasibility of achieving significant vibration control using a single VES, rather than multiple supports, was also investigated. A prototype of the optimized support was fabricated for experimental validation. The mathematical model proposed to describe the dynamic behavior of the composite system with VES is capable of adequately representing these systems and the methodology can be used to design simple VES for application in rotating machines. Furthermore, it was found that, with the application of a single VES, it is possible to obtain a large reduction in the response to unbalance. The study successfully demonstrates the practical applicability and structural efficiency of a simplified, optimally designed viscoelastic support for vibration control in rotating machinery. This contributes to overcoming key barriers to the broader adoption of VES, offering a promising solution for improving energy efficiency, reliability, and safety in industrial applications.
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DE OLIVEIRA SANTOS, GEANESSON ALBERTO;
DA SILVA ZANZARINI, ISADORA;
VALDAMERI, GLAUCIO;
ROTUNO MOURE VALDAMERI, VIVIAN;
DA SILVA, THIAGO ALESSANDRE;
CABRAL, PALOMA SOUZA;
JORGE, REGINA MARIA MATOS;
Alvaro Luiz Mathias;
FARIAS, FABIANE OLIVEIRA
Palavra-chave:
extração;
Biorefinery approach
Áreas do conhecimento:
Engenharias; Engenharia Química; Tecnologia Química; Alimentos
resumo ...
This study explored eco-friendly technology to optimize the production of hydroalcoholic peppermint natural extracts (NEP) and extend the shelf life of strawberries with natural, nontoxic substances while preserving their characteristics. Validated Response Surface Models for solid-liquid extraction demonstrated that optimal yields of total phenolic compounds (TPCop) at 38% ethanol and 65 °C and total flavonoids (TFCop) at 92% ethanol and 48 °C were influenced by ethanol concentration and temperature. Rosmarinic acid was the dominant compound in the lyophilized peppermint extract (L-)NEP with concentrations of 1.3 g/100 g central point, 1.2 g/100 g (L-)TPCop, and 5.4 g/100 g (L-)TFCop. Extraction conditions significantly impacted the metabolic profile, critical for food preservation and quality enhancement. Cell viability assays showed that (L-) NEP in aqueous solutions (A-)NEP have good biocompatibility, with IG50 values (concentrations able to decrease 50% of cell viability) at concentrations higher than 0.75 mg/mL. Strawberries treated with 0.5 mg/mL of (A-)NEP rich in phenols and stored at 2 °C had their shelf life extended by 77%. In contrast, treatment with 0.75 mg/mL rich in flavonoids extended it by 92% without affecting ripeness, epidermal firmness, total acidity, or soluble solids. This approach aligns with sustainable practices for green food technology, promoting health-conscious consumption and supporting socioeconomic development. Given the rising interest in sustainable and natural methods for food preservation, our research explored the remarkable potential of peppermint extracts. Our experimental findings revealed that hydroethanolic extracts of peppermint, confirmed to be nontoxic, can serve as effective natural additives for extending the shelf life of strawberries. Our findings open up potential routes for using natural extracts to preserve a wide range of food products. Solid-liquid extraction optimized yields of phenolic compounds and flavonoids. Rosmarinic acid was the dominant compound in hydroalcoholic peppermint extracts. Cell viability assays suggest that NEP solutions are biocompatible. Peppermint extracts extended strawberry shelf life by up to 92% with natural methods. Strawberry quality (firmness, acidity, ripeness) remained unchanged after NEP treatment.
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BAPTISTA, JOÃO;
SCHNEIDER, RICARDO;
ROSSI DE AGUIAR, KELEN MENEZES FLORES;
Módenes, A. N.;
Fabiano Bisinella Scheufele
Palavra-chave:
Carbonos mesoporosos ordenados;
adsorção;
Materiais carbonáceos;
Hard templating
resumo ...
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OLIVEIRA, DAYANA RUTH BOLA;
PROENÇA, MELISSA PASTORINI;
RISSON, KATHLEEN DALL BELO DE SOUZA;
NEVES JUNIOR, ALEX;
Jose Marques Filho;
POSSAN, EDNA
Palavra-chave:
Resíduos de construção e demolição;
otimização de finos;
sustentabilidade;
Economia Circular;
cimentos menos emissivos;
densidade de empacotamento
Áreas do conhecimento:
Engenharias; Engenharia Elétrica; Telecomunicações;
Engenharias; Engenharia Civil; Construção Civil; Tecnologia da Informação na Construção Civil;
Engenharias; Engenharia Civil; Construção Civil; Materiais e Componentes de Construção
resumo ...
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TESSARO, IRON;
HULTMANN AYALA, HELON VICENTE;
Viviana Cocco Mariani;
LEANDRO DOS SANTOS COELHO
Palavra-chave:
regressão simbólica;
métodos de regressão
Áreas do conhecimento:
Engenharias; Engenharia Elétrica; Inteligência Artificial;
Engenharias; Engenharia Elétrica; aprendizado de máquina
resumo ...
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FERREIRA, PATRÍCIA LOUISE DA SILVA;
SEQUINEL, RODRIGO;
MENDES, MAYARA DE LIMA;
TAMAMOTO, JULIANA YUKARI;
FERREIRA, JOÃO VITOR DA SILVA;
GONGORA, BENHURT;
SILVA, FABIANO ROSA DA;
MONTEIRO, MARCOS ROBERTO;
BARICCATTI, REINALDO APARECIDO;
Carlos Itsuo Yamamoto
Palavra-chave:
biodiesel;
BIOCOMBUSTÍVEIS
Áreas do conhecimento:
Engenharias; Engenharia Química; Biocombustíveis
resumo ...
(pt)
The use of fuel emulsions has garnered increasing attention over the past decade as a potential route to replace fossil fuels with more sustainable and technologically feasible alternatives. This study explores the incorporation of oxygenated biocomponents, such as refined vegetable oil, waste cooking oil, ethanol, and octanol, into diesel B S500 (a blend of diesel containing 10% biodiesel and 500 ppm sulfur). A key challenge associated with the high viscosity of vegetable oils, when used directly without prior transesterification, was successfully addressed by the addition of an ethanol/octanol cosolvent. Acting as a surfactant, the cosolvent enabled the formation of homogeneous and stable emulsions, maintaining stability for up to 90 days. The resulting fuel emulsions exhibited properties, including calorific value, viscosity, cold filter plugging point, oxidation stability, and atmospheric distillation, that were comparable with standard diesel B, ensuring suitability for common fuel applications. Engine performance tests showed similar results to diesel B, with certain formulations significantly reducing hydrocarbon and carbon monoxide emissions. Additionally, formulations incorporating neutralized waste cooking oil delivered promising outcomes, reinforcing the feasibility of repurposing waste oils. Fuel emulsions offer a complementary solution to the existing biodiesel industry, providing an environmentally sustainable alternative, particularly in regions distant from centralized processing facilities for vegetable oils and animal fats.
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MARTINS, M.C.;
LANGARO, E.A.;
FARIAS, M.M.;
Marcelo Henrique Farias de Medeiros
Palavra-chave:
durability of concrete;
sulfate attack;
Reinforced Concrete
Áreas do conhecimento:
Engenharias; Engenharia Civil; Inovação
resumo ...
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PROENÇA, MELISSA;
OLIVEIRA, DAYANA RUTH BOLA;
RISSON, KATHLEEN DALL BELLO DE SOUZA;
POSSAN, EDNA;
Marcelo Henrique Farias de Medeiros
Palavra-chave:
pozolanas;
Resíduos de construção e demolição
Áreas do conhecimento:
Engenharias; Engenharia Civil; Inovação
resumo ...
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