Analysis of SAW propagation in gratings on ZnO/diamond substrates
The space harmonic method is used to analyze surface acoustic wave (SAW) propagation under an infinite periodic metal grating on ZnO/diamond composite layered substrates. Dispersion properties for shorted and open gratings are derived as a function of the thickness of the grating electrodes. From these dispersion relations, the coupling of modes (COM) parameters are derived. Energy profiles inside ZnO/diamond show that the energies contained in each of the ZnO and diamond layers are of the same order when the thickness of the ZnO layer is P//spl pi/r (P=grating period) and that the energy is contained within two wavelengths below the ZnO/diamond interface.
Field analysis o SAW single-phase unidirectional transducers using internal floating electrodes
A coupled-mode analysis is presented of the performance of a single-phase unidirectional transducer utilizing the internal reflections of floating electrodes of electrically open circuited and shorted metal strips within an interdigital electrode. All four independent parameters (self- and mutual-coupling coefficients, transduction coefficient, and static capacitance) governing the coupled-mode equation with an electrical transduction term are analytically derived using extended Legendre polynomial expansions of electrical fields and a perturbation analysis. The frequency response of the radiation admittance and the insertion loss, and the growing surface acoustic wave (SAW) field distributions are calculated from simple closed-form solutions of the coupled-mode equation. The shift effect of reflection and transduction centers due to the asymmetric electrode structure is clarified. Experimental results are given for test devices fabricated on a 128 degrees YX LiNbO/sub 3/ substrate, and compared with the theory. The theoretical results are in good agreement with experiments.<<ETX>>
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.