At present, facial recognition entertains great importance in performing authentication processes, because it prevents unauthorized access to devices and places. Additionally, it allows for the identification of persons. Henceforth, this paper proposes a novel texture descriptor called Cyclical Chroma and a new classification technique, which takes in consideration the sub‐pixel values of 0–255 for each RGB (Red, Green, Blue) channel that conforms the image. To verify the effectiveness of the proposed techniques, tests were performed with a database of images in a controlled environment and in one under uncontrolled conditions; additionally, Cyclical Chroma was tested with a different classifier, denominated the Multiclass Classifier, and the results were compared against other descriptors, including GLCM, SHDH, LQP, and CCR, demonstrating the effectiveness of the proposed techniques with 100% efficiency with controlled images and 78% effectiveness under uncontrolled conditions prior to the application of an equalization technique, increasing the efficiency to 100%.

We synthesized the semiconductor oxide MnSb2O6 through a wet chemical process assisted by low-power microwave radiation. A gas-sensitive sensor was elaborated from the MnSb2O6 powders obtained by calcination at 600°C. The sensor was electrically characterized in static CO and C3H8 atmospheres by measuring direct current signals at 100, 200, and 300°C. The toxic gases’ concentrations were 1, 5, 50, 100, 200, 300, 400, and 500 ppm of C3H8; and 1, 5, 50, 100, 200, and 300 ppm of CO. From the MnSb2O6’s electrical resistance results, a sensor’s operational point and a low-cost analog circuit were proposed, obtaining two new prototypes: one for detecting C3H8 and a second one for detecting CO. We selected the response at 200°C and 5 ppm for both cases. Notably, this concentration (5 ppm) is selectable with a calibration resistance, generating an alarm signal of ≈11.3V at a supply voltage of 120 V AC. The toxic gas detectors showed excellent functionality. The resistive sensor showed high sensitivity and good electrical response, while the analog circuit presented a rapid response. Due to the operating temperature employed (200°C), these devices could find practical applications, for example, exothermic generators and heaters.

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