这是一篇有关外星智能探索的最新报道。Are we alone in thegalaxy?从早期的无线电信号到现代的大型望远镜阵,人类对地外文明探索的脚步从未停止过。科技空前发展、资金相对充足,笑容不仅洋溢在科学家的脸上,希望也会在每一个相信地外...这是一篇有关外星智能探索的最新报道。Are we alone in thegalaxy?从早期的无线电信号到现代的大型望远镜阵,人类对地外文明探索的脚步从未停止过。科技空前发展、资金相对充足,笑容不仅洋溢在科学家的脸上,希望也会在每一个相信地外文明存在的人心中升起。展开更多
Appropriate and adequate lighting at select locations on roadways is essential for roadway safety. As the lighting technologies advance, many Wpes of new lighting devices have been developed for roadway lightings. The...Appropriate and adequate lighting at select locations on roadways is essential for roadway safety. As the lighting technologies advance, many Wpes of new lighting devices have been developed for roadway lightings. The most promising new lighting technologies for roadway lighting include light emitting diode, induction, plasma, and metal halide lighting systems. A study was conducted to compare the new systems with the conventional high pressure sodium systems that are currently used on the Indiana roadway systems. In this study, the engineering issues, were analyzed such as illuminance, color rendering, power usage, cost effectiveness, and approval procedures for new roadway lighting systems. This paper, however, presents only the study findings related to cost effectiveness of the evaluated roadway lighting systems. Illustrated in this paper are the main features of the roadway lighting systems under evaluations, installations of the new lighting systems, measurements of power consumptions, and life cycle cost analyses of the lighting systems. Through this study, experience and knowledge have been obtained on the installations, power measurements, and cost effectiveness of the new types of the roadway lighting devices. The actual power values of various luminaires were obtained by measuring the electric current with a multi-meter. It was found that the differences between the rated and measured power values could be significant. The results of the life cycle cost analysis indicate that the lower life cycle costs of some of the alternative lighting devices are attributed to their relatively lower electricity usages and longer lamp/emitter replacement cycles.展开更多
文摘Appropriate and adequate lighting at select locations on roadways is essential for roadway safety. As the lighting technologies advance, many Wpes of new lighting devices have been developed for roadway lightings. The most promising new lighting technologies for roadway lighting include light emitting diode, induction, plasma, and metal halide lighting systems. A study was conducted to compare the new systems with the conventional high pressure sodium systems that are currently used on the Indiana roadway systems. In this study, the engineering issues, were analyzed such as illuminance, color rendering, power usage, cost effectiveness, and approval procedures for new roadway lighting systems. This paper, however, presents only the study findings related to cost effectiveness of the evaluated roadway lighting systems. Illustrated in this paper are the main features of the roadway lighting systems under evaluations, installations of the new lighting systems, measurements of power consumptions, and life cycle cost analyses of the lighting systems. Through this study, experience and knowledge have been obtained on the installations, power measurements, and cost effectiveness of the new types of the roadway lighting devices. The actual power values of various luminaires were obtained by measuring the electric current with a multi-meter. It was found that the differences between the rated and measured power values could be significant. The results of the life cycle cost analysis indicate that the lower life cycle costs of some of the alternative lighting devices are attributed to their relatively lower electricity usages and longer lamp/emitter replacement cycles.
