A new sensor-based self-configurable bandstop filter for reducing the energy leakage in industrial microwave ovens

In this work a new sensor-based self-configurable waveguide bandstop filter that uses a combination of metallic irises and reconfigurable posts for reducing the energy leakage in industrial microwave ovens is presented and validated through a procedure fully based on measurements. Several optimization and reconfiguration alternatives of the moving posts such as genetic algorithms and parametric sweeps are assessed. Results show that good attenuation values can be obtained for all the analyzed scenarios. In particular, genetic algorithms are shown as the best search strategy. Design and optimization times are also reduced when using the proposed filter compared to computer simulations

Electromagnetic equivalent models for printed circuit boards inside a metallic enclosure Using a coaxial-to-waveguide transition calibration

Equivalent models of printed circuit boards are useful to simplify electromagnetic problems by reducing the computational costs of numerical simulations. In this paper, a new procedure for obtaining a simple equivalent model of printed circuit boards inside metallic enclosures is presented. The equivalent model is obtained in two steps: first we precisely characterize the coaxial to waveguide transitions used during measurements by means of an inverse procedure and then during a second inverse procedure, we carry out simulations by concatenating these transitions and the equivalent model and comparing to measurements. The optimized parameters for the equivalent model are: thickness, dielectric constant and the electric conductivity. Results for a printed circuit board in three scenarios have been obtained by using a sweep and two different optimization techniques. Benefits and drawbacks of the model are discussed. Results indicate that this procedure produces very precise characterization of the equivalent model of PCBs depending on the position and orientation of this device within the enclosure.This work was supported in part by the Fundación Séneca, Agencia de Ciencia y Tecnología de la Región de Murcia, under the Séneca predoctoral fellowship with reference 16381/FPI/10 and under the project 00700/PPC/0

Quality control on radiant heaters manufacture

An inspection process of radiant heaters is presented in this paper. The proposed non destructive testing and evaluation (NDT and E) technique for defect assessment of radiant heaters is based on infrared thermography images properly acquired and processed. The technique can be used in on-line fabrication quality control radiant heaters manufacturing processes. By exciting the heater with a very short electrical pulse, a sequence of thermographic images is captured by an infrared camera and then analyzed. Regardless of the electrical excitation applied to the heating element of the heater, the electrical power supplied will dissipate at the resistor. Provided enough spatial resolution, the heaters could be tested with an infrared camera capturing the radiated heat. The analysis of the heating wire during the heating flank shows differences among pixels corresponding to defective points and pixels belonging to non-defective areas of the wire. The automation is provided by the development of an algorithm that looks for the slope of the heating evolution of each pixel. A Radon Transform based algorithm is here proposed to reduce human intervention providing just one image where an operator could quickly locate possible defects

Precise evaluation of coaxial to waveguide transitions by means of inverse techniques

In this paper, a new two-tier inverse characterization technique for coaxial to waveguide transition evaluation is presented and properly validated. The transition is characterized by estimating its scattering parameters and a cascade procedure is employed in order to compare simulations and measurements during the unterminating procedure. In contrast to other unterminating methods there are no restrictions concerning the number and type of standards and two transitions are simultaneously characterized. Additionally, genetic algorithms and the gradient descent method are used for error minimization during the unterminating stage. The accuracy of this two-tier inverse technique is evaluated as a function of the employed standards and the obtained results are compared to those provided by different well-known calibration algorithms. Results show that it is possible to properly characterize the coaxial to waveguide transition in a very flexible and accurate way

Gender differences in the COVID-19 pandemic risk perception, psychology, and behaviors of spanish university students

The actual COVID-19 pandemic scenario has generated a context of uncertainty, helplessness, and inequality. Yet, the perception of COVID-19 risk has influenced nutritional, psychological, and physical activity patterns depending on gender. We conducted the present research with the aim of studying gender differences of university students in the perceived risk of the COVID-19 pandemic, and in psychological, nutritional, oral health, and physical activity habits. To reach the study’s aim, 300 volunteer university students completed an online questionnaire which analyzed variables of perceived risk of the COVID-19 pandemic, psychological profiles, and nutritional, oral health, and physical activity habits. Results showed that females presented a higher perception of danger to the COVID-19 virus than males but showed no differences in how the pandemic has affected personal lives. Females showed higher values of anxiety, conscientiousness, neuroticism, and openness to experience, while males presented higher values of extraversion. Nutritionally, males presented greater consumption of soft drinks, meat, and pasta or rice, and lower buccal hygiene. Yet, no differences were found regarding physical activity patterns. Results from the present study could be used by various educational institutions to implement multidisciplinary interventions to reduce the stress and risk perception

Waveguide bandstop filter based on irises and double corrugations for use in industrial microwave ovens

In this reported work it is shown that one of the most employed filtering systems for use in continuous-flow industrial microwave ovens, namely doubly corrugated filters, does not work properly for many values of the electric permittivity of the processed material when it is partially filled. Thus, a novel bandstop filter which solves these inconveniences, based on a combination of metallic irises and double corrugations, is designed by means of CST Microwave Studio® and experimentally validated.This work was supported in part by the Fundación Séneca under the fellowship 16381/FPI/10 and the project 11689/PI/09

Increased Presentation of Diabetic Ketoacidosis and Changes in Age and Month of Type 1 Diabetes at Onset during the COVID-19 Pandemic in Spain

COVID-19; Aparició de la diabetis; Diabetis tipus 1COVID-19; Aparición de diabetes; Diabetes tipo 1COVID-19; Diabetes onset; Type 1diabetesObjective: To assess the impact of the COVID-19 pandemic and lockdown measures on the presenting characteristics (age at diagnosis, severity, monthly distribution) of newly diagnosed type 1 diabetes in Spanish children. Research Design and Methods: An ambispective observational multicenter study was conducted in nine Spanish tertiary-level hospitals between January 2015 and March 2021. Inclusion criteria: new cases of type 1 diabetes in children (0–14 years) recording age, sex, date of diagnosis, presence of diabetic ketoacidosis (DKA) at onset, and severity of DKA. Data were compared before and during the pandemic. Results: We registered 1444 new cases of type 1 diabetes in children: 1085 in the pre-pandemic period (2015–2019) and 359 during the pandemic (2020–March 2021). There was a significant increase in the group aged ≤4 years in the pandemic period (chi-squared = 10.986, df 2, p = 0.0041). In 2020–2021, cases of DKA increased significantly by 12% (95% CI: 7.2–20.4%), with a higher percentage of moderate and severe DKA, although this increase was not significant. In 2020, there was a sharp decrease in the number of cases in March, with a progressive increase from May through November, higher than in the same months of the period 2015–2019, highlighting the increase in the number of cases in June, September, and November. The first three months of 2021 showed a different trend to that observed both in the years 2015–2019 and in 2020, with a marked increase in the number of cases. Conclusions: A change in monthly distribution was described, with an increase in DKA at onset of type 1 diabetes. No differences were found in severity, although there were differences in the age distribution, with an increase in the number of cases in children under 4 years of age

Filtro autoconfigurable para horno microondas de procesado en línea, proceso de filtrado autoconfigurable para hornos microondas de procesamiento en línea y horno microondas de procesamiento en línea.

Número de publicación: 2 334 549 Número de solicitud: 200900734Filtro autoconfigurable para hornos microondas (1) de procesado en línea, que comprende medios configurados para la variación automática y adaptativa de la geometría interior de dicho filtro mediante la inserción de una pluralidad de pivotes deslizantes (5) configurados para variar perpendicularmente su distancia respecto de la cavidad de guías de ondas (2) de tal manera que actúen como elementos metálicos reactivos atenuantes de los principales modos que se propagan desde el interior del horno hacia el exterior, generando discontinuidades que cortan dichos modos de campo electromagnético.Universidad Politécnica de Cartagen

Diseño de Anillo Térmico para el Patrón Nacional de Ruido

En ese trabajo se presentan los aspectos fundamentales de una parte fundamental del que será patrón nacional de ruido térmico: el anillo que realiza el contacto térmico entre los conductores interior y exterior en la parte superior de la línea coaxial del patrón de ruido. El objetivo de este dispositivo es mantener la misma temperatura en ambos conductores a la entrada del patrón y, asimismo, minimizar el efecto que pueda tener sobre la temperatura de ruido y el coeficiente de reflexión a la entrada del patrón