Application of the photo-elastic method to measurement of dynamic stress distribution for NS-GT cut quartz crystal resonators
NS-GT cut quartz crystal resonators are widely used as a frequency standard element in consumer products and communication equipment. The vibration mode of the resonators was analyzed by the finite element method (FEM) because they have a complicated shape. As a result, an asymmetrical vibration mode at the main resonant frequency has been obtained by the FEM simulation. But, it is necessary to confirm the asymmetrical vibration mode experimentally because it is just a simulation. In this paper, stress distributions of the NS-GT cut quartz crystal resonators are measured experimentally by using a dynamic photo-elastic method when the resonators are vibrating in the resonant frequency; thereafter, vibration modes of the NS-GT cut resonators are estimated with the experimental data of the stress distributions. This experiment for the NS-GT cut quartz crystal resonators exposes the existence of a twisted asymmetrical vibration mode at the main resonant frequency, with the magnitude of the twisted vibration in proportion to thickness of the resonators.
Finite element and experimental results of transverse vibration for GT-cut and SC-cut quartz plates with fixed and free boundary conditions and multiple methods of excitation
This study presents complete results of the dynamic characteristics for GT-cut and SC-cut quartz plates at resonance from experimental measurements and numerical calculations. The quartz plates are excited from applying voltage and acoustic waves on the surfaces. The first experimental method, amplitude–fluctuation electronic speckle pattern interferometry (AF-ESPI), can provide the resonant frequencies and the correspondent full-field vibration mode shapes at the same time. The second method, laser Doppler vibrometer (LDV), is used to verify the results of resonant frequencies measured by AF-ESPI. The investigation is focused on the cantilever and completely free quartz plates and the experimental measurements are compared with the results obtained by the finite element method (FEM). Three electrode designs for quartz plates with free boundary conditions were provided to study the influence of electrode on vibration characteristics of quartz plates.
Concentration of amino acids in wine after the end of fermentation by Saccharomyces cerevisiae strains
Both quantitative and qualitative differences in the utilization and release of assimilable nitrogen by two wine strains of Saccharomyces cerevisiae (cerevisiae and capensis) under different conditions of oxygen were observed. These differences were influenced by the presence of oxygen at the beginning of the fermentation, and by the strain of S cerevisiae. The release of some amino acids post-fermentation may be the result of reoxidation of NAD(P)H in order to maintain a normal redox balance. Copyright © 2003 Society of Chemical Industry