The steady-state oscillation of a zero-voltageswitching clamped-voltage self-oscillating ballast driven by a saturable transformer is analyzed and simulated. Its selfoscillating operation is divided into six stages according to the hysteresis B–H loop of saturable transformer cores. Stage-wise circuit analysis shows the saturable transformer limits the lamp current and dominates the switching f...

Ballast bed deformation is significantly influenced by its internal stress state. However, investigations concerning ballast focus mainly on the behaviour under various ...

The ballast water treatment method consists of bubbling the inert gas via a row of pipes (orifices at the bottom of the pipes) located at the bottom of the tank, while maintaining a negative pressures of -2 psi at the ullage space. The inert gas from a standard shipboard inert gas generator is composed of 84% Nitrogen, 12-14% CO2 and 2% Oxygen. The ballast water will be equilibrated with gas fr...

The most important oyster farming area in Europe is in a close proximity of two medium size merchant ports. Cargo ships deballast in this area before loading, releasing unwanted or noxious marine species. During a sampling campaign aboard these arriving ships, we found in some ballast water samples a huge number of potentially toxic dinoflagellates and some potentially pathogenic bacteria. A mo...

The flooding of railway ballasts can cause extensive damage. This process has been the subject several experimental investigations. In present work, a relatively easy to implement approach modelling this fluid flow is presented. It shown that good agreement with results obtained. modelled by Darcy’s law, which we extend free flowing above ballast. main complexity in determining surface position...

The seismic failure behavior of railroad ballasts in response to earthquakes was analyzed using Discontinuous Deformation Analysis.Several sinusoidal waves with different frequencies and accelerations were inputted into the discontinuous numerical model of a railroad ballast ,which consists of an assemblage of polygonal crushed stones,rails,sleepers and a roadbed .The dependencies of railroad f...

Recently in Japan, railway ballasts have been flown out several times by heavy or intense rainfalls. However, the mechanism has not yet been investigated in detail, so that the risk and the countermeasures cannot be reasonably proposed. Therefore, in this research, model tests and numerical analyses were conducted to investigate the flow-out mechanism. It was found that the seepage characterist...

Biological invasions from ballast water are a severe environmental threat and exceedingly costly to society. We identify global hot spots of invasion based on worldwide patterns of ship traffic. We then estimate the rate of port-to-port invasion using gravity models for spatial interactions, and we identify bottlenecks to the regional exchange of species using the Ford-Fulkerson algorithm for n...

The North American Great Lakes have been invaded and dramatically altered by more than 145 alien species. Many invasions have occurred during the past few decades because of the release of Eurasian ballast water from transoceanic ships. Current regulations require ships to exchange foreign ballast with highly saline water before entering the Great Lakes; this procedure should prevent colonizati...