Marine risers transporting unsteady multiphase flows may experience internal flow-induced vibrations depending on several flow-structure parameters. This study presents an experimental investigation of large-amplitude intermittent inclined bendable riser air-water flow that exhibits slug pattern. The has initial catenary profile with a length over diameter about 320. By using non-intrusive meas...

To fully understand the environmental and ecological impacts of the Deepwater Horizon disaster, an accurate estimate of the total oil released is required. We used optical plume velocimetry to estimate the velocity of fluids issuing from the damaged well both before and after the collapsed riser pipe was removed. We then calculated the volumetric flow rate under a range of assumptions. With a l...

We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system be...

the use of acoustic waves in researches related to sea water is of most importance among scientistsrecently. since these waves are the only waves, transmitted in water with lowest attenuation and high speed, they canbe used in many scientific fields. the main goal of this research is to better understand the physics and mechanismsof sound-seabed interaction, including acoustic penetration, prop...

Autonomous underwater vehicles (AUVs) are robotic platforms that are commonly used to map the sea floor, for example for benthic surveys or for naval mine countermeasures (MCM) operations. AUVs create an acoustic image of the survey area, such that objects on the seabed can be identified and, in the case of MCM, mines can be found and disposed of. The common method for creating such seabed maps...

For FY14, the first objective was to investigate the statistics of the mode intensity that result from scattering from a randomly rough seabed surface in a shallow water environment. The specific objective was to examine the feasibility of using a 2-way coupled mode methodology to analyze observed monostatic reverberation collected off Panama City, FL in 2013 in the 2-4 kHz band. The second obj...

For FY14, the first objective was to investigate the statistics of the mode intensity that result from scattering from a randomly rough seabed surface in a shallow water environment. The specific objective was to examine the feasibility of using a 2-way coupled mode methodology to analyze observed monostatic reverberation collected off Panama City, FL in 2013 in the 2-4 kHz band. The second obj...

This paper proposes an original method for the 3-D reconstruction of seabed from multiple sidescan sonar images. The proposed method adopts a stereo-like vision approach based on a combination of the GPS positioning and the image matching technology to correspond among multiple sidescan sonar images taken from different viewmints. and then estract the 3-D structure information of 'seabed from t...

There are different mechanisms of seabed scattering which are due to different types of seabed medium irregularities, which are roughness of the seabed interfaces, and volume heterogeneity: continuous (spatial fluctuations of the sediment acoustic parameters) and discrete scatterers (or sediment inclusions, such as relatively large shells and shell fragments). Given different environmental cond...

Seabed sediments of commercial ports are often characterized by high pollution levels. Differences in number and distribution of bacteria in such areas can be related to distribution of pollutants in the port and to sediment conditions. In this study, the bacterial communities of five sites from Leghorn Harbor seabed were characterized, and the main bacterial groups were identified. T-RFLP was ...