Electronic ballasts are designed to fulfill a variety of different input and output specifications depending on their end application and performance requirements. These designs typically include non-PFC, passive PFC and active PFC input stages, and, single, dual or multi-lamp output stages. The input voltage requirements for each design can vary significantly depending on the final application...

Screening methods to prevent introductions of invasive species are critical for the protection of environmental and economic benefits provided by native species and uninvaded ecosystems. Coastal ecosystems worldwide remain vulnerable to damage from aquatic species introductions, particularly via ballast water discharge from ships. Because current ballast management practices are not completely ...

the track stiffness experienced by a train will vary along the track. sometimes the stiffness variation may be very large within a short distance. one example is when an unsupported sleeper is hanging in the rail. track stiffness is then, locally at that sleeper, very low. at insulated joints the bending stiffness of the rail has a discontinuity implying a discontinuity also of the track stiffn...

Recent studies with numerical models regarding edge protection systems (EPS), class C according to standard EN 13374, showed that some requirements are inadequate for human safety. This problem mainly arises when a person is injured by falling directly against the EPS supports. To analyse this subject, three series of numerical models, in accordance with EN 13374, have been produced. The paper ...

There are high functioning and low functioning ballast water treatment systems on board ships. In this study, five systems were analysed so as to methodically examine the operational difficulties for ship crew members while giving important consideration to sustainable environment practices. Multi-criteria analysis, a questionnaire, survey and interviews were used as the research method so as t...

Enactment of any environmental policy should be followed by an evaluation of its efficacy to ensure optimal utilization of limited resources, yet measuring the success of these policies can be a challenging task owing to a dearth of data and confounding factors. We examine the efficacy of ballast water policies enacted to prevent biological invasions in the Laurentian Great Lakes. We utilize fo...

Ballast flying problems obsess the ballasted high speed railway, its microscopic mechanics is less of discovered. In the paper, the railway ballast particle force equilibrium is analyzed through basic mechanics and mathematic formula, and a model is set up to discover the factors and influence. The microscopic ballast flying model is used for ballast bed geometry and ballast shape optimization,...

To prevent the dramatic degradation of the device performance of SiGe power heterojunction bipolar transistors (HBTs) and maintain the power efficiency, emitter-ballast resistors and base-ballast resistors have been employed in high power bipolar transistors. The microwave performance of emitter-ballast and base-ballast HBTs has been compared and discussed empirically in the previous work. Howe...

Ballast degradation can cause poor drainage, settlement and reduced lateral stability, which adversely affect railroad track safety and performance. Two indices are commonly used in the North American railroad industry to quantify the level of ballast degradation. These are (i) Fouling Index (FI) and (ii) Percentage Fouling (PF). Identifying these two traditional indices involve ballast samplin...