Resin Transfer Molding (RTM) is a widely used composite manufacturing process where liquid resin is injected into a closed mold filled with a fibrous preform. By applying this process, large pieces with complex shapes can be produced on an industrial scale, presenting excellent properties and quality. A true physical phenomenon occurring in the RTM process, especially when using vegetable fibers, is related to the absorption of resin by the fiber during the infiltration process. The real effect is related to the slowdown in the advance of the fluid flow front, increasing the mold filling time. This phenomenon is little explored in the literature, especially for non-isothermal conditions. In this sense, this paper does a numerical study of the liquid injection process in a closed and heated mold. The proposed mathematical modeling considers the radial, three-dimensional, and transient flow, variable injection pressure, and fluid viscosity, including the effect of liquid fluid absorption by the reinforcement (fiber). Simulations were carried out using Computational Fluid Dynamic tools. The numerical results of the filling time were compared with experimental results, and a good approximation was obtained. Further, the pressure, temperature, velocity, and volumetric fraction fields, as well as the transient history of the fluid front position and injection fluid volumetric flow rate, are presented and analyzed.

Neste trabalho são apresentados resultados analíticos a respeito da aplicabilidade da Transformada de Fourier no processamento de sons. Fez-se um estudo simplificado do desenvolvimento matemático de Fourier para funções ou sinais: contínuos ou discretizados em uma ou duas dimensões, periódicos ou não, apresentando e provando algumas de suas propriedades importantes no tratamento dos sons. O presente trabalho teve como objetivo principal realizar uma pesquisa bibliográfica acerca da série de Fourier e suas transformadas com a aplicação na compactação das ondas sonoras. Foram utilizados textos de PEREIRA (2021), SOUZA (2022) e MACHADO (2023).Como resultado, verificou-se que a Transformada contribuiu significativamente para a existência da música compactada no modo de streaming, transformando grandes arquivos em pequenos arquivos.

Um ambiente não projetado para a ocupação humana contínua, que possua meios limitados de entrada e saída e onde possa existir atmosfera perigosa é definido como espaço confinado. Devido aos riscos inerentes às atividades nesses ambientes, é comum que ocorram acidentes, demandando, em muitos casos, uma perícia criminal nestes locais, visando estabelecer o que aconteceu, como aconteceu e quem são os responsáveis pelo sinistro. Entretanto, os peritos criminais que atendem a esse tipo de ocorrência geralmente não estão adequadamente treinados para tal, fato esse agravado pela carência, na literatura nacional, de um documento consultivo simplificado para guiar o trabalho pericial em espaços confinados. Assim, o presente trabalho tem o objetivo de produzir um protocolo de atuação do perito criminal em locais de acidente de trabalho em espaços confinados, com foco na segurança da equipe pericial, na avaliação técnica do local e na avaliação documental complementar à cena periciada.

Resin Transfer Molding (RTM) is a broadly applied composite fabrication technique in which liquid resin is injected into a sealed mold housing a fibrous preform. This technique enables the industrial-scale production of large, complex-shaped components while ensuring high quality and excellent material properties. A notable phenomenon in the Resin Transfer Molding process, particularly when vegetable fibers are used as reinforcement, involves resin absorption by the fibers during the filling process, which causes a deceleration of the fluid flow front, leading to an increase in mold filling time. This phenomenon has been scarcely investigated in the scientific literature, particularly under non-isothermal situations. In this context, this paper focuses on the resin injection in a closed and heated mold, emphasizing the evaluation of the capillary number of the fluid flow. The model incorporates a transient, radial, and 3D flow, variable resin viscosity, and includes the effect of resin absorption by the fibers. Simulations were carried out using CFD techniques, evaluating the effect of fixed injection gauge pressure (2.0 bar) or volumetric flow rate (3.5 × 10⁻⁸ m³/s) on the infiltration transient behavior. The numerical results of the capillary number of the flow, resin viscosity, and resin superficial velocity as a function of radial position were analyzed. Based on the analysis of the capillary number field, with the sole objective of minimizing the potential formation of voids in the manufactured composite, optimal operating parameters were identified, namely, a mold heating temperature of 30 °C and an optimal resin injection condition consisting of a constant volumetric flow rate of 3.5 × 10⁻⁸ m³/s. Further, the volumetric fraction, pressure, and temperature fields are presented and examined. The numerical modeling used builds upon a previously validated numerical framework and extends its application by evaluating the potential generation of voids through the analysis of the capillary number field.