Transition zones in railway tracks are locations with considerable changes in the vertical stiffness of the rail support. Typically they are located near engineering structures, such as bridges, culverts, tunnels and level crossings. In such locations, the differential settlement always exists and continually grows without proper maintenance. Due to the effect of the differential settlement and...

The unintentional introduction of nonindigenous species by ballast water discharge is one of the greatest threats to biodiversity in freshwater systems. Proposed international regulations for ballast water management will require enumeration of viable plankton in ballast water. In this study we analyze the efficacy of vital stains in determining viability of freshwater taxa. The efficacy of vit...

To minimize the dispersal of aquatic nuisance species through shipping, ballast water can be treated to kill, remove, or inactivate organisms. Ultraviolet (UV) radiation is used in some ballast water management systems to address this goal. Because UV treatment renders cells nonviable (by sterilizing them, preventing reproduction) and does not necessarily kill organisms instantaneously, the eff...

Fluorescent lamps are non-linear devices that exhibit negative resistance over the useful range of operation. At low frequency, this negative resistance peculiarity is passed through during each period of the AC driving current [1]. When the fluorescent lamp operates at high frequency, the negative resistance is associated with the average power rather than with the instantaneous, cycle by cycl...

With the growth of maritime traffic and the use of large ships, ballast water has become a leading dispersing agent of harmful organisms (David et al., 2007; Souza et al., 2001). According to Ruiz et al. (2000) human pathogens are also being transported through ballast water. As an example, we mention a cholera epidemic occurred in Peru in 1991 and quickly spread through Latin America (McCarthy...

In this article, we determined the concentration levels of metals including Zn, Al, Sr, and Co and metalloid of As of ballast water in commercial ships entering Bushehr port, along the Persian Gulf. Ballast water samples were taken from commercial ships entering Bushehr port from 34 ports around the world during 15 February and 25 August 2016. The concentration levels of metals and metalloid we...

This paper presents analytical tools aimed at improving and simplifying the development of frequency-controlled dimming electronic ballasts. A modified phasor transformation is proposed that converts a frequency-modulated signal into an equivalent time-varying phasor. The proposed transformation is applied to develop a complete small-signal phasor model of the LCC resonant ballast, which explic...

The discharge of nutrients, phytoplankton and pathogenic bacteria through ballast water may threaten the Cayo Arcas reef system. To assess this threat, the quality of ballast water and presence of coral reef pathogenic bacteria in 30 oil tankers loaded at the PEMEX Cayo Arcas crude oil terminal were determined. The water transported in the ships originated from coastal, oceanic or riverine regi...

It is known, that track deterioration (loss of its geometry) strongly depends on track support conditions, particularly on the ballast. In this paper a novel approach is presented to predict the evolution of track vertical irregularities due to vehicle-track dynamic interaction taking into account ballast stiffness with dry friction. An applied vehicle-track model is composed of a railway car a...