acoustic emission


The dynamic problem of determining the wave field of displacements on the surface of an elastic half-space caused by the opening of an internal mode II crack has been solved. Using the method of boundary integral equations, a change in the amplitude-frequency characteristics of elastic oscillations on the surface of a solid body depending on the size of the defect, its depth, and the distance from the epicenter to the observation point was determined.

Research of acoustic emissions from the system of complanary cracks

The dynamic problem of the displacement field in an elastic half-space caused by the timesteady displacement of the surfaces of the system of disc-shaped coplanar cracks is solved. The solutions are obtained by the method of boundary integral equations. The dependences of elastic displacements on the surface of the half-space on the wave number, the number of defects and the depths of their occurrence are constructed.

Визначення координат джерел при об'ємній локалізації дефектів методом акустичної емісії

The mathematical providing of construction of models of determination of co-ordinates of sources of acoustic emission and algorithms of search of defects is offered. Description of layout of sensors charts is given.  The calculation formulas of determination of co-ordinates of spatial localization of sources of acoustic emission are offered. Procedure of non-destructive control and  technical diagnostics of metal of constructions is described.

Antimicrobial Packaging Materials from Poly(Lactic Acid) Incorporated with Pectin-Nisaplin® Microparticles

The thermostability of nisin and Nisaplin® was investigated in the presence and absence of pectin. By mixing with pectin, both nisin and Nisaplin® were able to inhibit microbial growth, even after heating to 433 K. In contrast, without pectin, the nisin was totally inactivated after heat treatment. Nisin and pectin in solution were complexed, as shown by atomic force microscopic analysis. Probably, the complex formation between the polysaccharide and the polypeptide improves the nisin thermostability; however, a detailed mechanism remains to be resolved.