The subsurface defect in the wheel tread caused from Rolling Stock Fatigue (RCF) has become more danger in high speed railway. The conventional UT and phased array UT have deficiency to find the subsurface defect from the tread surface because of limitation of ultrasonic near field. In this paper, the subsurface defect is studied by simulation and experimental results with ultrasonic technique....

Shotand offset-domain common image gathers encounter problems in complex media. They can place events that come from different points in the subsurface at one subsurface location based on identical arrival times and horizontal slownesses. Angle-domain common image gathers uniquely define ray couples for each point in the subsurface, therefore each event in the data will be associated with only ...

The adsorption of atomic oxygen and its inclusion into subsurface sites on Ag(210) and Ag(410) surfaces have been investigated using density functional theory. We find that—in the absence of adatoms on the first metal layer—subsurface adsorption results in strong lattice distortion which makes it energetically unfavoured. However subsurface sites are significantly stabilised when a sufficient a...

ii ACKNOWLEDGMENTS I would like to acknowledge the following for completion of this thesis: God for giving me the patience, guidance and strength to succeed in this research. I am so grateful for everything I have been given and everything I was able to do. Without God I can do nothing. Dr. Nandita Basu for challenging and guiding me throughout graduate school and this research. I have grown an...

We perform first-principles calculations to investigate the initial stages of titanium nanoparticle oxidation. We determine the most stable structure of a 181-atom decahedral nanoparticle with various oxygen coverages ranging from a single atom to full oxidation of the surface. Linear Oad−Ti−Oad bonding configurations on the nanoparticle surface are found to be most stable for low oxygen covera...

background: natural methods of wastewater treatment, such as wetlands, are simple, cheap and acceptable for developing countries, especially small and remote cities. the aim of this study was to evaluate the efficiency of typha latifolica in subsurface flow constructed wetland for wastewater treatment. methods: in this experimental research, the efficiency of typha latifolica in subsurface flow...

This paper presents a novel compact factored subsurface scattering representation for optically thick, heterogeneous translucent materials. Our subsurface scattering representation is a combination of Tucker-based factorization and a linear regression method. We first apply Tucker factorization on the intensity profiles of the heterogeneous subsurface scattering responses. Next, we fit a polyno...

We investigated the role of increasingly well-constrained geologic structures in the subsurface (i.e., subsurface architecture) in predicting streambed flux and hyporheic residence time distribution (RTD) for a headwater stream. Five subsurface realizations with increasingly resolved lithological boundaries were simulated in which model geometries were based on increasing information about flow...