The aim of the present work was to search a convenient, simple and inexpensive method to determine the metals in electroplating hydroxide sludges. The analytical methods are characterized by sensitivity, selectivity and accuracy but for economic reasons and of course the availability of equipments and products, the UV-visible spectrophotometry was used. We have undertaken the study of the influence of different cations present in the same solution on the determination of metal. After conducting several tests on solutions prepared in the laboratory and then on the solutions used to dissolve different samples of industrial waste, the result revealed that it is possible to use spectrophotometric method to assess the amount of metals in electroplating sludges, provided that we followed a well-defined scheme so as to avoid all the possible interference.
Impact of nonlinear piezoelectric constants on surface acoustic wave propagation on a piezoelectric substrate is investigated in this work. Propagation of acoustic wave propagation under uniform stress is analyzed; the wave equation is obtained by incorporating the applied uniform stress in the equation of motion and taking account of the set of linear and nonlinear piezoelectric constants. A new method of separation between the different modes of propagation is proposed regarding the attenuation coefficients and not to the displacement vectors. Detail calculations and simulations have made for Lithium Niobate (LiNbO3); transformations between modes of propagation, under uniform stress, have been found. These results leads to conclusion that nonlinear terms affect the acoustic wave propagation and also we can make controllable acoustic devices.
