Use of non-destructive eddy current technique to detect simulated corrosion of aircraft structures

The article deals with the issue of non-destructive testing of riveted joints. In the article, the authors used a non-destructive eddy current array technique, which was applied to detect simulated corrosion in the field of aircraft riveted joints of aluminum sheets. In aircraft maintenance, the eddy current method is used to control the outer surface of the aircraft skin, especially the areas around the riveted joints. This method makes it possible to detect hidden cracks and corrosion that may occur during aircraft operation. Especially hidden are hidden cracks and corrosion of aircraft structures, which cannot be detected during a visual inspection of the aircraft. The aim of the experimental measurements was to reveal simulated corrosion in the area of riveted joints formed on the experimental sample. Corrosion was simulated by gluing aluminum powder to the surface of the aluminum sheets from which the sample was made. The simulated corrosion in the second and third layers of the riveted sample was reliably detected. The settings, the method of control and the results of measurements are given in the article in the experimental part and the results of measurements. Measurements were performed using a defectoscope with an ECA measurement module, with appropriate measuring probes suitable for this type of inspection

Influence of turbulent mixing on critical behavior of directed percolation process: Effect of compressibility

Universal behavior is a typical emergent feature of critical systems. A paramount model of the nonequilibrium critical behavior is the directed bond percolation process that exhibits an active-to-absorbing state phase transition in the vicinity of a percolation threshold. Fluctuations of the ambient environment might affect or destroy the universality properties completely. In this work, we assume that the random environment can be described by means of compressible velocity fluctuations. Using field-theoretic models and renormalization group methods, we investigate large-scale and long-time behavior. Altogether, 11 universality classes are found, out of which 4 are stable in the infrared limit and thus macroscopically accessible. In contrast to the model without velocity fluctuations, a possible candidate for a realistic three-dimensional case, a regime with relevant short-range noise, is identified. Depending on the dimensionality of space and the structure of the turbulent flow, we calculate critical exponents of the directed percolation process. In the limit of the purely transversal random force, critical exponents comply with the incompressible results obtained by previous authors. We have found intriguing nonuniversal behavior related to the mutual effect of compressibility and advection. © 2018 American Physical Society

Influence of turbulent mixing on critical behavior of directed percolation process: Effect of compressibility

Universal behavior is a typical emergent feature of critical systems. A paramount model of the nonequilibrium critical behavior is the directed bond percolation process that exhibits an active-to-absorbing state phase transition in the vicinity of a percolation threshold. Fluctuations of the ambient environment might affect or destroy the universality properties completely. In this work, we assume that the random environment can be described by means of compressible velocity fluctuations. Using field-theoretic models and renormalization group methods, we investigate large-scale and long-time behavior. Altogether, 11 universality classes are found, out of which 4 are stable in the infrared limit and thus macroscopically accessible. In contrast to the model without velocity fluctuations, a possible candidate for a realistic three-dimensional case, a regime with relevant short-range noise, is identified. Depending on the dimensionality of space and the structure of the turbulent flow, we calculate critical exponents of the directed percolation process. In the limit of the purely transversal random force, critical exponents comply with the incompressible results obtained by previous authors. We have found intriguing nonuniversal behavior related to the mutual effect of compressibility and advection. © 2018 American Physical Society