Definition of linear color models in the RGB vector color space to detect red peaches in orchard images taken under natural illumination

This work proposes the detection of red peaches in orchard images based on the definition of different linear color models in the RGB vector color space. The classification and segmentation of the pixels of the image is then performed by comparing the color distance from each pixel to the different previously defined linear color models. The methodology proposed has been tested with images obtained in a real orchard under natural light. The peach variety in the orchard was the paraguayo (Prunus persica var. platycarpa) peach with red skin. The segmentation results showed that the area of the red peaches in the images was detected with an average error of 11.6%; 19.7% in the case of bright illumination; 8.2% in the case of low illumination; 8.6% for occlusion up to 33%; 12.2% in the case of occlusion between 34 and 66%; and 23% for occlusion above 66%. Finally, a methodology was proposed to estimate the diameter of the fruits based on an ellipsoidal fitting. A first diameter was obtained by using all the contour pixels and a second diameter was obtained by rejecting some pixels of the contour. This approach enables a rough estimate of the fruit occlusion percentage range by comparing the two diameter estimates.

Rotational Doppler effect in magnetic resonance

We compute the shift in the frequency of the spin resonance in a solid that rotates in the field of a circularly polarized electromagnetic wave. Electron-spin resonance, nuclear magnetic resonance, and ferromagnetic resonance are considered. We show that contrary to the case of the rotating LC circuit, the shift in the frequency of the spin resonance has strong dependence on the symmetry of the receiver. The shift due to rotation occurs only when rotational symmetry is broken by the anisotropy of the gyromagnetic tensor, by the shape of the body or by magnetocrystalline anisotropy. General expressions for the resonance frequency and power absorption are derived and implications for experiment are discussed.

Trompa interestelar : el color sonoro de la trompa en la "llamada interestelar" de O. Messiaen

Mi trabajo versa sobre la obra de O. Messiaen "Des Canyons aux etoiles" (De los cañones a las estrellas), y en particular de uno de los movimientos de la obra: "Appel Interestellaire" -N.VI- (Llamada Interestelar) -para trompa sola-. Se estructura en dos partes. La primera se centra en su contexto histórico -como, cuando y para quien fue compuesta-; análisis formal, armónico, melódico, rítmico; y aspectos estéticos. La segunda parte está vinculada con la interpretación de la obra. Se realiza un análisis para la interpretación -técnica de la trompa, efectos sonoros, timbres-; se hace una comparación entre la interpretación de 2 diferentes trompistas, y por último, aporto mi propuesta de interpretación. El trabajo se cierra con una conclusión, bibliografía, y un extracto con anexos (esquema, partitura y datos o imágenes de interés).