Binary excitation of a high-Q bulk acoustic microresonator by actuation polarity inversion

We present a technique for independently exciting two resonant modes of vibration in a single-crystal silicon bulk mode microresonator using the same electrode configuration through control of the polarity of the DC actuation voltage. Applications of this technique may include built-in temperature compensation by the simultaneous selective excitation of two closely spaced modes that may have different temperature coefficients of resonant frequency. The technique is simple and requires minimum circuit overhead for implementation. The technique is implemented on square plate resonators with quality factors as high as 3.06 × 106. Copyright © 2008 by ASME.

Anchor limited q in flexural mode resonators

This paper reports a preliminary examination of the effect of anchor geometry design on the quality factor of flexural mode resonators operating in vacuum using both FE simulation and measurements of resonator frequency response. Three types of structures have been considered in this study: an elliptical mode ring, a double ended tuning fork, and a doubly-clamped beam. We consider the relative distribution of strain energies in both the resonant structure and the connecting stem, which is indicative of the measured quality factor. The measured quality factors of the different structures are compared against each other, based on which suggestions are proposed for optimizing the anchor limited quality factor (Q) in flexural mode micromechanical resonators. ©2008 IEEE.

La sacra doctrina y el gnosticismo : (S. Th., I, q. 1, art. 1)

El estudio de la falsa gnosis es algo de lo cual varios pensadores católicos ya han escrito y lo siguen haciendo. Sin embargo, la consideración de este argumento a la luz del pensamiento de Santo Tomás de Aquino no es algo común. El concepto de gnosis (gnw/sij, conocimiento), en sí mismo, no significa algo peyorativo. Por el contrario, Jesucristo hace referencia a los doctores de la ley que han quitado la llave de la ciencia (Lc 11, 52). Por su parte san Pablo confiesa que «no hay sino un solo Dios y Padre, de quien proceden todas las cosas, y nosotros estamos destinados hacia él; y un solo Señor Jesucrito, por quien son todas las cosas, y nosostros también por él. Pero no en todos se halla esa ciencia (h` gnw/sij)». Este conocimiento o gnosis que toma la Revelación en la fe por regla y guía es la gnosis verdadera Nos proponemos en este trabajo realizar una lectura del art. 1º de la Iª Pars de la Suma Teológica y compararlo ante todo con el fundamento mismo de aquello que san Pablo denomina como «la mal llamada ciencia»...

Research on Q-Switched Nd : YAG laser engraving

IN this paper, the engraving process with Q-Switched Nd:YAG laser is investigated. High power density is the pre- requisition to vapor materials, and high repetition rate makes the engraving process highly efficient. An acousto- optic Q-Switch is applied in the cavity of CW 200 W Nd:YAG laser to achieve the high peak power density and the high pulse repetition rate. Different shape craters are formed in a patterned structure on the material surface when the laser beam irradiates on it by controlling power density, pulse repetition rate, pulse quantity and pulse interval. In addition, assisting oxygen gas is used for not only improving combustion to deepen the craters but also removing the plasma that generated on the top of craters. Off-focus length classified as negative and positive has a substantial effect on crater diameters. According to the message of rotating angle positions from material to be engraved and the information of graph pixels from computer, a special graph is imparted to the material by integrating the Q- Switched Nd:YAG laser with the computer graph manipulation and the numerically controlled worktable. The crater diameter depends on laser beam divergence and laser focal length. The crater diameter changes from 50 micrometers to 300 micrometers , and the maximum of crater depth reaches one millimeter.

Distribución de "coxiella burnetii" en los rumiantes domésticos y en la fauna silvestre de la Comunidad Atutónoma Vasca. Evaluacióndel efecto del tratamiento antibiótico y de la vacunación en el control de la fiebre Q en rebaños ovinos naturalmente infectados

243 p. : il.

Avances en espectrometría de masas con fuente de plasma: Análisis simultáneo de elementos mayores y trazas mediante Q-ICP-MS y análisis isotópicos de Sm-Nd mediante HR-MC-ICP-MS. Aplicación en estudios geoquímicos

186 p. : il.