DSpace Collection: Producción científica documental revisada por pares, indizada en base de datos Web of Science

Dielectric properties of guava, mamey sapote, prickly pears, and Nopal in the microwave range

2025-09-22T16:32:26Z

Title: Dielectric properties of guava, mamey sapote, prickly pears, and Nopal in the microwave range Authors: Kaur Kataria, Tejinder; Olvera-Cervantes, José Luis; Corona-Chávez, Alonso; Rojas-Laguna, Roberto; Sosa-Morales, María Elena Abstract: Dielectric properties (DPs) of selected fruits: guava (Psidium guajava), mamey sapote (Pouteria sapota), red prickly pear (fruit from Opuntia streptacantha), and white prickly pear (fruit from Opuntia ficus-indica), as well as nopal (young cactus pads or cladodes from Opuntia ficus-indica) were studied. DPs were determined using the open-ended coaxial probe method at microwave frequencies (500 MHz–2 GHz) and temperatures of 20, 40, and 60ºC. At 20ºC and 915 MHz for unripe fruits, dielectric constant values ranged from 65.7 to 70.9, while the loss factor had values between 8.4 and 20.7. Both dielectric constant and dielectric loss factor were affected by temperature and frequency (p < 0.05). For example, loss factor for red prickly pear at 2450 MHz decreased from 13.88 at 20ºC to 12.8 at 40ºC and 11.7 at 60ºC. DPs of fruits were also affected by their ripening (quantified through the maturity index). In addition, penetration depth decreased with increasing frequency, ranging from 1.98 to 4.80 cm at 915 MHz and from 0.25 to 0.41 cm at 5800 MHz. Results are valuable to develop further applications with microwave technology for these foods, such as microwave- assisted disinfestation treatments or microwave drying.

Dielectric properties of in-shell and shelled sunflower seeds (Helianthus annuus L.) and pine nuts (Pinus pinea L.) at different temperatures for radio and microwave frequencies

2025-09-22T16:33:57Z

Title: Dielectric properties of in-shell and shelled sunflower seeds (Helianthus annuus L.) and pine nuts (Pinus pinea L.) at different temperatures for radio and microwave frequencies Authors: Hernandez-Nava, Ruth; Meza-Arenas, Juan Mateo; Sarmiento-Narvaez, Diego; Kaur Kataria, Tejinder; Corona-Chávez, Alonso; Rojas-Laguna, Roberto; Sosa-Morales, María Elena Abstract: The bulk permittivity (εbulk) and particle permittivity (εpart) of in-shell and shelled sunflower seeds (Helianthus annuus L) and pine nuts (Pinus pinea L.) were determined in a temperature range of 20–60°C and a frequency range of 27–5000 MHz using the transmission line method. Additionally, the samples were analyzed for moisture content, water activity (aw,), fat content, color, and densities (bulk, tapped, and particle). The dielectric constant (ε’) decreased with increasing temperature for sunflower seeds (from 3.04 to 2.63 for in-shell samples) and increased with temperature for pine nuts (from 4.41 to 5.48, also for in-shell seeds), due to the differences in the aw values. For all samples, the ε’ and loss factor (ε’”) decreased with increasing frequency. ε” and ε’” values increased with higher bulk density; for instance, at frequency of 915 MHz, in-shell sunflower seeds (ρbulk = 0.341 g/cm3) had ε” = 1.49 and ε’” = 0.02 at 20°C, while in-shell pine nuts (ρbulk = 0.601 g/cm3) had ε” = 2.53 and ε’’ = 0.03 at 20°C. Higher penetration depth (dp) values were found at lower frequencies, for example, shelled sunflower seeds at 60°C exhibited dp = 7.52 at 27 MHz, but dp = 1.20 m at 5000 MHz. Results are valuable for designing further radiofrequency and microwave treatments for these seeds and nuts.

Truck Axle Weights and Interaxle Spacings from Traffic Surveys in Mexican Highways

2025-09-22T16:37:56Z

Title: Truck Axle Weights and Interaxle Spacings from Traffic Surveys in Mexican Highways Authors: García-Soto, Adrián David; Pozos-Estrada, Adrián; Hernández-Martínez, Alejandro; Valdés-Vázquez, Jesús Gerardo Abstract: In structural and bridge engineering, the axle weights and interaxle spacings of heavy trucks are useful for assessing the capacity of existing bridges, developing live load models, and other issues. Weigh-in-motion data have become the most common source for recording axle weights and interaxle spacings; however, information is not as direct and may not be as precise as that from static surveys. Surveying vehicles by stopping them beside the highway is not common nowadays; nevertheless, surveys provide very reliable information on truck axle weights and interaxle spacing. In this study, data from three surveys on two Mexican highways recorded in 2016 and 2018 are provided. The data contain the gross vehicular weights, axle weights, and interaxle spacings of heavy trucks. The discussion is given as to how the provided information can be useful for the bridge and transportation engineering community and for reliability and code calibration tasks for Mexican bridges and a future design code for bridges in Mexico City. It is concluded that statistical values are consistent with WIM data, with differences due to different methods used, recording time, samples size and others, and that trucks heavier than the legal weight circulate in Mexican highways; static surveys are useful to strongly support this important issue. Further research to compare samples from different surveying techniques, as well as the use of the information to investigate load effects on bridges, is recommended.