New streetlight design curbs light pollution

For astronomers, a well-lit city means a sky unavailable for study. Worse, light pollution is blamed for affecting bird migration, sea turtle hatching, and wildlife mating and feeding routines. Researchers at National Central University, Taiwan, and Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Mexico, have attacked the problem with a new LED street lamp designed to shine only where needed, without splashing into unwanted areas, as a way to reduce light pollution while providing better lighting.Current street lights often use high-pressure sodium or mercury lamps, and can spill light in unwanted directions, resulting in glare, non-uniform light patterns, upward-reflected light, and wasted energy. In some cases, nearly nearly half the light is lost by the light flooding horizontally and vertically, and conventional street lamp design has trouble adapting to different street lighting layouts, whether the lamps are set in the middle of the road, above it or in a zigzag pattern.

The research team proposes a new LED street lamp design based on a three-part lighting fixture, with the first part containing a cluster of high-efficiency LEDs. These use Total Internal Reflection (TIR) lenses, which focuses the light into parallel rays. The LEDs are mounted inside a reflecting cavity that helps keep the light from scattering and, as it leaves the unit, light is passed through a diffuser to reduce glare. According to the team, this design allows the lamp to project a uniform rectangle of light over a given area.

Continental United States as seen at night from the Suomi NPP satellite (Image: NASA Earth...

The LED street lamp was studied in simulation to determine the spread at a distance of 10 meters (33 ft) from the light source. This was measured by the team as the optical utilization factor (OUF), which describes the relationship between the flow rate of light at the target and the flow rate of light coming directly out of the LEDs. A higher OUF indicates better performance.

The simulation showed an OUF of 51 to 81 percent, compared to a conventional street lamp’s “excellent” performance of 45 percent. The proposed street lamp loses only two percent of its light as direct pollution and reduces energy consumption by 40 to 60 percent. The team also claims that the new lamp is relatively easy to fabricate because it only has four parts, with the LED component already an industry standard.

The team plans to have a working prototype within three to six months, followed by practical installations of the new street lamp as early as next year.

Comments

Recycled, solar-powered, boat-roofed wonder wins Shed of the Year

The crowning glory is a 14-ft boat which has been left whole and inverted to form the roof. A 20-W solar panel powers the creature comforts inside. To create the shed's frame, the boat was fixed atop four telegraph poles plonked judiciously on a hillside amid Wales' Cambrian Mountains. (The views aren't at all bad, either). Aluminum-framed windows were salvaged from a 1940s caravan, and others were "borrowed" from Holland's farmhouse. Walls are a mixture of corrugated metal and, for a taste of the Neolithic, wattle and daub. Inside things take a turn for the high tech. The shed's PV panel feeds a battery which provides power to LED lighting and a 12-V sound system – the only new item in the construction. The shed also boasts a plumbed Belfast sink (the generous, cuboid-shaped ones), and a 19th century wood burning stove for heat fitted with a chimney fashioned from the queen pole of an old circus big top.Where sheds end and (sometimes pretentious) ...

New type of silicone exhibits both viscous and elastic properties

Looking for a more effective solution to the all-too-common wobbly table dilemma than a folded up bit of cardboard or piece of rubber under the leg, University of Virginia physicist Lou Bloomfield created a new type of silicone rubber called Vistik – it's malleable enough to take on any shape when pressed, but is still resilient enough to offer support, as it gradually starts to return to its original shape as the pressure is released. The material could have many applications ... beyond just steadying up wobbly tables. Vistik is a viscoelastic material, meaning that it exhibits both viscous and elastic properties. As a result, when compared to something such as conventional silicone rubber, there’s a considerable time lag in its response to continuous pressure. “It seems elastic in response to sudden forces or impacts, denting in proportion to the sudden, brief stress and then returning almost instantly to its earlier shape when that stress is removed,” Prof. Bloomfield ex...

Roadless wheel concept adjusts to all terrains

Graduate student Ackeem Ngwenya has combined the 6000 year-old wheel with modern materials to develop a new type of all-terrain wheel assembly that switches from narrow to wide tread at the turn of a screw. His Roadless wheel system, while envisioned for rural applications in his native Malawi, has the potential to be as big a change to road (and off-road) transport as was the introduction of anti-lock braking. We've all done it. Before embarking on a long driving trip on smooth-surfaced interstate highways or other roads of national importance, we'll raise the tire pressure to boost the gas mileage a bit. Stuck in the snow, mud, or sand? Let some pressure out of the tires to increase the contact area, while at the same time increasing the chances that the now floppy tire will grab hold. However, the benefits of trying to change the aspect ratio of a tire by simply changing pressure are rather minor, and often associated with a significant loss in tire lifetime. The Road...

ANBARASUASOKAN

Search This Blog