This paper proposes a hybrid control strategy for a single-phase Totem-Pole Bridgeless Rectifier (TPBR), modeled as an affine switched system combining controlled and autonomous dynamics under parametric uncertainties. The TPBR is analytically characterized as a current-dependent system, with modes consolidated into two per current half-cycle, without loss of generality, preserving the nonlinear behavior through switching. Such formulation enables a two-stage evaluation of the Switching Rule (SR), fully computed offline through Linear Matrix Inequalities (LMIs) posed over a polytopic uncertainty set. This guarantees Lyapunov-based stability while tracking a sinusoidal reference for the inductor current across the entire admissible range, which remains one of the main challenges in switched control. The control architecture adopts a nested-loop structure, where this SR acts in the inner loop performing current control by directly driving the switches without modulation, while the outer loop employs a PI compensator to regulate the output voltage indirectly by generating the current reference. Experimental validation was performed under sinusoidal excitation on a TMS320F28377S-based prototype with input voltages of 85 V, 127 V, and 220 V, and load levels of 100 W, 200 W, and 300 W. The proposed algorithm exhibits negligible computational cost in real-time and results confirm stable voltage regulation at 380 V, unity power factor, and fast transient recovery under load and input voltage variations.
The aim of this study was to analyze the association between sleep quality and daytime sleepiness with sociodemographic, clinical, and behavioral variables during the COVID-19 pandemic in physically active and inactive older adults. An observational cross-sectional study was conducted with 150 older adults (88
The present study evaluates numerically the thermophysical properties of polymer melts during the filling phase. The mathematical model corresponds to the transient and incompressible Navier-Stokes equations, solved by the Ansys-Fluent® software, using the generalized Newtonian formulation. The results also show that geometric transitions and proximity to the advancing flow front strongly affect velocity gradients, leading to localized increase in shear rate and pressure, particularly near cavity walls and smoothing radius. Temperature distribution indicates formation of a frozen layer near the mold walls, while the flow core remains close to the inlet temperature due to dominant convective effects. Overall, the numerical framework enables accurate monitoring of the filling dynamics and provides quantitative insights into the thermophysical conditions governing polymer melt flow, thereby contributing to improved prediction of filling-related defects and optimization of injection molding process parameters.
Humulus lupulus L. (hops) is essential in brewing due to its contributions to bitterness, flavor, and aroma. This study compared the volatile profiles of five commercially important hop varieties-Amarillo, Ariana, Cascade, Centennial, and El Dorado-grown in their main regions of origin (United States for Amarillo, Cascade, and El Dorado; Germany for Ariana; and Brazil for Centennial). Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS) enabled the identification of 312 volatile compounds, including monoterpenes (e.g., myrcene, linalool, geraniol), sesquiterpenes (e.g., humulene, caryophyllene), esters, alcohols, aldehydes, and ketones. Amarillo showed the highest myrcene content (22.61% of the total volatile area), while Centennial was distinguished by elevated gamma-muurolene (20.59%), and El Dorado by the highest level of undecan-2-one (10.47%), highlighting marked varietal differences in key aroma-active constituents. Multivariate, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), clearly discriminated the five varieties: PC1 (41.04% of the variance) separated samples enriched in fruity/floral monoterpenes and esters from those dominated by woody/resinous sesquiterpenes, whereas PC2 (25.93% of the variance) reflected variation in medium-chain esters, ketones, and waxy compounds. These chemometric patterns demonstrate that both genetic background and growing region terroir strongly shape hop volatile composition and, consequently, aroma potential, providing brewers with objective criteria for selecting hop varieties to achieve specific sensory profiles in beer.
Arbuscular mycorrhizal fungi (AMF) establish a mutualistic symbiosis with most terrestrial plants. Mycorrhizal colonization begins with fungal spore germination in soil, a critical stage for symbiosis establishment, and is therefore highly susceptible. Among the compounds that may negatively affect AMF, imidacloprid has been identified as a potential stressor. In this context, the present study aimed to investigate the effects of the insecticide imidacloprid, as the active ingredient, on the pre-symbiotic phase of Acaulospora morrowiae, Gigaspora margarita, and Rhizophagus clarus. The substrate used for the in vitro assays was tropical artificial soil (TAS). The concentrations tested were 0, 2, 4, 8, 16, 32, 64, 128, 256, and 512 mg imidacloprid kg–1 of TAS for A. morrowiae and G. margarita; and 0, 1, 2, 4, 8, 16, 32, 64, 128, and 256 mg imidacloprid kg–1 of TAS for R. clarus. Imidacloprid reduced spore germination in all AMF species across all tested concentrations. However, A. morrowiae was the most sensitive species, with an IC50 of 23 mg kg–1. Although all AMF species evaluated in this study showed inhibition of spore germination upon exposure to imidacloprid, their responses differed among species, likely due to distinct morphological characteristics.
