A local defect resonance for linear and nonlinear ultrasonic thermography

An efficient wave-defect interaction is the key to a high thermal response of flaws in ultrasonic thermography. To selectively enhance defect vibrations a concept of local defect resonance is developed and applied to ultrasonic activation of defects. The frequency match between the defect resonance frequency and the probing ultrasonic wave results in a substantial rise of a local defect temperature. The defect resonance is accompanied by depletion of the excitation frequency vibration due to nonlinear frequency conversion to higher harmonics. The local generation of higher frequency components provides a high thermal defect response in such an acoustically nonlinear thermography mode

Defect scaling Lee-Yang model from the perturbed DCFT point of view

We analyze the defect scaling Lee-Yang model from the perturbed defect conformal field theory (DCFT) point of view. First the defect Lee-Yang model is solved by calculating its structure constants from the sewing relations. Integrable defect perturbations are identified in conformal defect perturbation theory. Then pure defect flows connecting integrable conformal defects are described. We develop a defect truncated conformal space approach (DTCSA) to analyze the one parameter family of integrable massive perturbations in finite volume numerically. Fusing the integrable defect to an integrable boundary the relation between the IR and UV parameters can be derived from the boundary relations. We checked these results by comparing the spectrum for large volumes to the scattering theory.Comment: LaTeX, 33 pages, 9 figures, figures adde

Defect Branes

We discuss some general properties of "defect branes", i.e. branes of co-dimension two, in (toroidally compactified) IIA/IIB string theory. In particular, we give a full classification of the supersymmetric defect branes in dimensions 2 < D < 11 as well as their higher-dimensionalstring and M-theory origin as branes and a set of "generalized" Kaluza-Klein monopoles. We point out a relation between the generalized Kaluza-Klein monopole solutions and a particular type of mixed-symmetry tensors. These mixed-symmetry tensors can be defined at the linearized level as duals of the supergravity potentials that describe propagating degrees of freedom. It is noted that the number of supersymmetric defect branes is always twice the number of corresponding central charges in the supersymmetry algebra.Comment: Latex2e paper, 28 pages, no figures. Footnote adde

Study of defect formation in Al 7050 alloys

The Al 7050 alloy is an Al-Zn-Mg-Cu-Zr alloy having good mechanical properties. This alloy has been developed in order to overcome stress corrosion cracking problems that characterise 7xxx Al alloys. Despite Al 7050 is widely used for aerospace applications, it can be subjected to crack initiation and propagation during the manufacturing process. In this work cracked Al 7050 components have been analysed in order to identify possible causes of crack formation such as coarse intermetallic phase presence, voids or wrong mechanical machining processes