Effects of electrodes with continuously varying thickness on energy trapping in thickness-shear mode quartz resonators.

We studied the effect of electrodes with varying thicknesses on thickness-twist modes in a piezoelectric plate resonator of crystals of 6 mm symmetry. The focus is on the effects of asymmetric electrodes, which do not seem to have been examined before. A theoretical analysis is performed using the theory of linear piezoelectricity. A trigonometric series solution is obtained that is relatively rare from the equations of piezoelectricity. Numerical calculations are made based on the series solution. Results show that asymmetric, nonuniform electrodes have a strong effect on vibration mode shapes. This effect offers the possibility of using nonuniform electrodes in design to achieve various goals. The quantitative results in this paper are useful for the purpose.

Vibration of a thickness-twist mode piezoelectric resonator with asymmetric, nonuniform electrodes

Using the Stevens–Tiersten equation for slowly varying thickness modes in doubly rotated quartz plate piezoelectric resonators, we determine optimal electrode shape and size for these resonators. The electrodes obtained are optimal in that they satisfy Bechmann’s number in every direction.

Optimal electrode shape and size of doubly rotated quartz plate thickness mode piezoelectric resonators

Electrically forced vibration of a thickness-twist mode piezoelectric resonator with non-uniform electrodes

Bachelor ́s thesis compares organic and conventional agriculture in terms of its energy balance. First part covers the history of organic agriculture in the Czech Republic and informs about the law and rules which are the organic farmers obligated to follow. Chapter involves charts and maps demonstrating present state and spatial arrangement of organic farms in the Czech Republic. Second part of the thesis examines researches from aboard, which are focused on energy comparison of agriculture in different husbandry systems. Third part is a comparison of three apple orchards in the Czech Republic. The research reveals, that the sample organic farm needs less than one third of the energy consumed by the conventional farm. On the other hand, the amount of the fruit harvested is smaller. Energy efficiency is comparable for conventional farm and orchard in transition period and lower for sample organic farm.

/pdf/technicka-univerzita-v-liberci-4gjt5ltquu.pdf

Technická univerzita v Liberci

We study the possibility of using electrodes of varying thickness for strong energy trapping in quartz thickness-shear resonators as an alternative for contoured resonators. A theoretical analysis is performed. Results show that nonuniform electrodes can produce strong trapping of thickness-shear modes

Lijun Sheng

Papers

Effects of electrodes with varying thickness on energy trapping in thickness-shear quartz resonators