نتایج جستجو برای: ballast
تعداد نتایج: 1836 فیلتر نتایج به سال:
Biological invasions have the potential to cause extensive ecological and economic damage. Maritime trade facilitates biological invasions by transferring species in ballast water, and on ships' hulls. With volumes of maritime trade increasing globally, efforts to prevent these biological invasions are of significant importance. Both the International Maritime Organization and the Australian go...
ships’ ballast water has apparently enabled numerous species to expand their ranges to environments in which they did not evolve (Carlton 1998; Cohen and Carlton, 1998; Ruiz et al., 2000). In normal trading operations, ships load seawater ballast in one port, then discard it at another in exchange for cargo. Modern international voyages span just a few days or weeks, affording entrained organis...
Organisms, including Vibrio cholerae, can be transferred between harbors in the ballast water of ships. Zones in the Caribbean region where distance from shore and water depth meet International Maritime Organization guidelines for ballast water exchange are extremely limited. Use of ballast water treatment systems could mitigate the risk for organism transfer.
Most harmful diatoms belong to the marine, planktonic genus Pseudo-nitzschia and are responsible for amnesic shellfish poisoning through the production of domoic acid. Fifteen Pseudo-nitzschia species, nine of them toxigenic (approximately 60% of the species found in our samples) were recovered from 185 ship ballast tanks (water and sediment) destined for Canadian ports. Our results demonstrate...
Design and analysis of a new singleswitch soft-switching class-E electronic ballast with high input power factor is presented. Design equations for the optimum operating condition are derived and complete computer analysis performed. It is shown that low duty-cycle control of the class-E ballast can reduce the voltage stress of the controlled switch. A 40-W fluorescent lamp ballast is implement...
A digitally addressable digital dimming ballast has been developed. It conforms to DALI standard requiring very few parts and operates at very low power. Applications include building management or studio lighting where it is desired to control single or groups of lamps for conserving energy, performing lamp maintenance or creating prefect light quality. The design includes the digital dimming ...
This paper presents a high-frequency electronic ballast for HID lamps. A new fixed frequency dimming method with low EMI features is developed in this research. The proposed electronic ballast has the advantages of high power density, simple circuit and low EMI features. The circuit operating principle and design procedures are described in detail. A laboratory prototype was built and tested. T...
A novel single-stage push–pull electronic ballast with high input power factor is presented in this paper. The proposed electronic ballast combines the front-end power-factor corrector and push–pull converter into a single-stage converter. Compared to the single-stage class-D electronic ballast, the proposed circuit does not require an isolated driver. The control of the circuit is easier and t...
The use of electromagnetic induction lamps without electrodes has increased because of their long life and energy efficiency. The control of the ignition and luminosity of the lamp is provided by an electronic ballast. Beyond that, the electronic ballast also provides a power factor correction, allowing the minimizing of the lamps impact on the quality of service of the electrical network. The ...
A novel ballast resistor network is proposed to achieve a better thermal management in HBT power cells without degrading the RF performances. Experiments were conducted on two HBT power amplifiers. They occupy same area. One was designed using conventional ballast network. The other uses proposed novel network. Temperature comparisons were made based on the same current density. Infrared camera...
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