Robust Linear Longitudinal Feedback Control of a Flapping Wing Micro Air Vehicle

This paper falls under the idea of introducing biomimetic miniature air vehicles in ambient assisted living and home health applications. The concepts of active disturbance rejection control and flatness based control are used in this paper for the trajectory tracking tasks in the flapping-wing miniature air vehicle (FWMAV) time-averaged model. The generalized proportional integral (GPI) observers are used to obtain accurate estimations of the flat output associated phase variables and of the time-varying disturbance signals. This information is used in the proposed feedback controller in (a) approximate, yet close, cancelations, as lumped unstructured time-varying terms, of the influence of the highly coupled nonlinearities and (b) the devising of proper linear output feedback control laws based on the approximate estimates of the string of phase variables associated with the flat outputs simultaneously provided by the disturbance observers. Numerical simulations are provided to illustrate the effectiveness of the proposed approach

HEAT TRANSFER ENHANCEMENT IN A HORIZONTAL CHANNEL BY THE ADDITION OF CURVED BAFFLES

ABSTRACT This paper presents the heat transfer and flui

Sonido, Ultrasonido y Cavitación

We present in an accessible way and avoiding the mathematical language the main characteristics of the phenomenon of cavitation. We intend to provide the concepts to understand the conditions of generation, development and implosion of the bubbles created by the passage of a sound wave of a certain frequency and intensity in an aqueous medium. The effect of cavitation on the surface structure of the leaves of aquatic lirium plants exposed to sonic or ultrasonic irradiation is discussed.Presentamos en una forma accesible y evitando el lenguaje matemático las principales características del fenómeno de la cavitación. Pretendemos proporcionar los conceptos para entender las condiciones de generación, desarrollo e implosión de las burbujas creadas al paso de una onda sonora de determinada frecuencia e intensidad en un medio acuoso. Se comenta sobre el efecto de la cavitación en la estructura superficial de las hojas de las plantas de lirio acuático expuestas a irradiación sónica o ultrasónica

Application of photoacoustic spectroscopy in the study of optical absorption in n-type porous silicon

The application of the photoacoustic spectroscopy technique in the study of the optical absorption spectrum in samples of porous silicon n-type is reported. A spectral range of 250 to 800 nm and modulation frequencies of 200 Hz were used. The differential optical absorption spectrum obtained shows two significant absorption bands, one in the visible region and the other in the UV region, which is consistent with the quantum confinement model. These optical absorption remarkable properties give porous silicon a particular importance for its application as a photothermal material.Se reporta la aplicación de la técnica de espectroscopía fotoacústica en el estudio del espectro de absorción óptico en muestras de silicio poroso tipo n. Se utilizó un rango espectral de 250 a 800 nm y frecuencias de modulación del haz monocromático de 200 Hz. El espectro de absorción óptico diferencial obtenido muestra dos importantes bandas de absorción, una en la región visible y la otra en la región UV, que es consistente con el modelo de confinamiento cuántico. Estas notables propiedades de absorción óptica dan al silicio poroso una importancia particular para su aplicación como material fototérmico