In regression neural networks for pattern recognition of preprocessed guided waves signals in beams, a trained network produced large errors when identifying a test pattern not found in the training set. To improve the accuracy of results, a new neural network procedure was introduced where progressive training was performed in a series combined network with the integration of a weight-range se...

kinetic study of epoxidation of unsaturated ketone of mesityl oxide was studied by usinghydrogen peroxide in the presence of dodecyltrimethyl ammonium bromide (dtab) as aninverse phase transfer catalyst. the reaction was carried out in the two-phase media of waterheptanewith 1:1 ratio in 25 °c. it was found that the order of reaction for mesityl oxide forketone concentration in the range of 0.0...

Several different strategies are being considered for ultrasonic structural health monitoring systems using a variety of approaches. Guided wave techniques for interrogating large plate-like structures have probably generated the most interest; these methods have the potential of monitoring large areas with a low sensor density while remaining sensitive to defects. The acousto-ultrasonic nondes...

This effort explores the evolution and characterization of structural cracks in aircraft fuselage structures in which the loads are varying. During flight, an aircraft fuselage skin and structure are subjected to varied cyclic loads, which can cause embedded cracks and other damage features to change their characteristics due to loading effects. The current research uses finite element modeling...

a new method for the synthesis of nano zero-valent iron (nzvi) was developed in the present study.ultrasonic waves, as a novel method, were used to synthesize the nanoparticles. the morphologyand surface compositions of the particles were characterized by using fesem, xrd, bet, andparticle size analyzer. the synthesized nanoparticles were then utilized as a fenton-like catalyst todegrade of hyd...

All manned spacecraft are vulnerable to leaks generated by micrometeorite or debris impacts. Methods for locating such leaks using leak-generated, structure-borne ultrasonic noise are discussed and demonstrated. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum are used to find the location of the leak. Four methods for sensing and processing leak noise have been develope...

The availability of military platforms is affected by design methods, damage detection, maintenance, and logistics. Structural health monitoring provides a means of detecting damage, which can be used to predict future structural performance of the platform and effectively schedule maintenance. Ultrasonic guided waves can be employed as an active structural health monitoring technique in a vari...

Thin walled large structures are widely used for pipes, bridges, wings and body of aircrafts, and automobile bodies. To maintain such large structures, in addition to visual inspection, non-destructive testing with X-ray and ultrasonic is periodically implemented for essential parts. In ultrasonic non-destructive testing, ultrasonic pulse echo technique is generally used, in which plate thickne...