[lolaa]

re bonjour,
je viens de parcourir une grande partie de votre site... une merveille !!! merci d'exister

voyance par mail

[lolaa]

Ça ne fait pas longtemps que je me suis inscrit sur ce forum, mais je le trouve super !
Voyance serieuse

[3Dfernseher101]

Although LEDs have been available for almost a decade for lighting purposes, they are still not as widely used as the traditional incandescent bulbs, which cost a lot during use both the customer and the environment.

There are several reasons why these highly energy-saving and environment friendly lighting solutions are not all over the market. After their first application in the household their performance was not satisfactory for most consumers, were very expensive and most of the lights were suitable for décor purposes only due to their short lifespan and low performance. A lot has changed since then, and the LEDs now available on the market – still constantly improving – can be used non-stop and many are bright enough to replace a 60W halogen light. By now, consumers are able to enjoy the full advantages of LED lighting.

Efficiency, longevity, durability, safety, environment, colour – are the keywords of LED advantages. LED lights are 90% more energy-efficient; can have a lifespan up to 100 000 hours; they are solid state lighting devices, and therefore insensitive to shock, vibration and extreme temperature; they are cool running, so safe to the touch; fully recyclable and contain no poisonous substances; and are available in any colours.

In a similar manner, the keywords to improving LED technology could be cost, performance and design. As LEDs are clearly the best lighting solutions available, the majority of people deciding against LED lights are discouraged by the price they have to pay at the time of purchase. White light LEDs currently available on the market are expensive to produce, since they include sapphire wafers. Also, LED lighting is different from the traditional incandescent lights in the sense that their light is directional and therefore do not give the appearance of a very bright light, since they illuminate only certain areas.

Researches in both areas (reducing the cost of production and increase the light emitted by single LEDs) are successful, and their latest results are expected to be on the market within a few years time. Several research groups work on creating more cost-effective production technologies. One of the best know of these is Prof. Colin Humphreys team at the University of Cambridge. The research group created an LED using gallium nitride grown on silicone wafers instead of the previous, highly expensive sapphire wafers. This makes the production of LEDs ten times cheaper, which is the greatest achievement of the group. The lights also have a 100 000 hours lifespan, and are dimmable.

The other field of research is to get more light from a single LED of 1W. CREE lighting is a leading researcher in the area, announcing in February 2010 the achievement of 208 lumens gained from a single Watt. The colour temperature of the light was 4579W, which is colour temperature closer to cold white, but not bluish at all. The greatest achievement in the result is the high efficiency of the LED, with a higher than general conversion rate at lower operating voltage. Although the achievement is great, we will have to wait a few years to get this on the market. Also, Cree produces probably the best available quality on the market, it is quite difficult to afford their products for an every-day user, as their prices are often three times as high as of any other LED products.

Both achievements mentioned above will take time to get to the market of household use also for the reason of design difficulties. LEDs generally create much less heat compared to incandescent lights. However, they still emit some, and LEDs are very sensitive to overheating and lose some of their lifespan due to this quite quickly. This is where design comes in: LEDs need bulbs designed with excellent thermal management, or heat sinks to circulate the air around them. Nuventix SynJet believes to have the best solution to this problem. Their latest invention is a smaller – and therefore more easily adjustable – turbulent device that pushes air to the LED heat sinks to cool the LEDs. This makes it possible to use smaller heat sinks, as well as higher performance LEDs within the limited space of a light bulb, and longer lifespan of LEDs up to 100,000 hours.


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