Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror

Comment Re:From the laundromat (Score 2) 88

The problem with nuclear power comes in two forms:

The increased regulation isn't a separate thing; it's just a reaction to the potentially catastrophic results of a failure. When a small mistake can lead to a catastrophic failure that leaves the region around the plant uninhabitable for decades at the very least, people within the potentially affected area will demand regulations to make sure even small mistakes don't happen. This happens in any field where small mistakes can have terrible consequences on bystanders.

Comment Re:Natural Gas & Coal (Score 2) 88

With all the talk of Santa Ana Winds I think there's an opportunity to build some of these wind farms in SoCal.

The Santa Anas are the wrong kind of wind for power generation because they blow only part of the time but very strongly when they are blowing. That means you need to build the turbines to be very strong to resist the peak winds, but you won't get to benefit from that strength most of the time. The ideal winds for power generation are more or less constant speed.

That said, there is a fair amount of wind power generation in Southern California. There are large wind farms built to take advantage of the wind funnel effects of the San Gorgonio and Tehachapi passes.

Comment Re:I guess he started to stink . . . (Score 4, Insightful) 145

For honored dead, it was called lying in state, for dishonored it was parading the body, but in both cases the reason was the same: to get as many witnesses as possible to the fact the person was well and truly dead. Otherwise, there would be persistent rumors that they were still alive, people pretending to be them (or their children born after their official date of death), and the like. So it was gruesome but completely practical.

And it's not as if the need for this kind of thing has completely gone away. There are still people who are rumored to be alive long after their deaths, like Elvis Presley. In the fight against terrorism, there have been several cases where the US has published pictures of the obviously dead bodies of prominent enemies as a way of proving they're actually dead, and there was considerable speculation among conspiracy theorists about why Osama bin Laden's body was disposed of so quickly.

Comment Re:Hold it right there (Score 2) 51

It's not as much the manufacturer as it is the statistics for the light. Look for lights with the color temperature you like, an acceptable Color Rendering Index (CRI, 90+ is best, 80+ is OK, below 80 is not worth considering), and then efficiency in lumens per watt. Any LED light that meets US EnergyStar requirements will be acceptable, since they require a CRI of at least 80, but I'd try to find higher than that.

The lights I'm so happy with are fluorescent tube replacements, rather than screw-in bulb replacements. They require you to bypass the fluorescent ballasts, which involves some electrical skill and may mean replacing your existing tube holders. They give almost 100 lumen/watt in a daylight balanced tube (a bit less in warm white) that seems to have an acceptable CRI. Their biggest drawback is that their light is a bit less diffuse than the T12 fluorescent tubes they replaced, so I needed to upgrade my diffusers as well as my lights.

That said, I think the biggest change is going to be in new forms of lighting that aren't drop-in replacements for existing bulbs and tubes. LEDs are different technology, and they have different inherent strengths and weaknesses from existing lighting technology. Specifically, they are individually small and produce only a bit of light, and they are more heat sensitive than other light sources. That means they do best when they're spread over a large area to provide diffuse light and avoid overheating. Cramming them into an incandescent bulb replacement makes them immediately useful, but it doesn't play to their strengths as light sources. That will only happen when we design completely new light sources that take full advantage LEDs' inherent advantages.

Comment Re:Visually Efficient? (Score 1) 51

If you know where to shop, you can get high (90+) CRI fluorescent tubes in just about any color temperature. A lot of the manufacturers seem to have standardized on a three digit code to describe the lights, with the first digit giving the approximate CRI and the final two giving the color temperature. So a 927 tube would be 2700K with a 90+ CRI and a 641 would be 4100K with a CRI of about 60. If you buy a cheap tube without a labeled color or CRI, it will probably be a 641, which are the nasty, old fashioned ones that give fluorescent lighting such a bad reputation. 800 series tubes are a bit more expensive but give fairly good light and comparable efficiency to the 600 series. 900 series give really nice light that closely approximates a continuous spectrum, but lose some efficiency compared to the 800 series. I have 950 tubes in my remaining fluorescent tube fixtures, and they look great compared to the 641s I had before; colors really pop, and skin looks natural.

Unfortunately, most CFLs don't include a CRI on the packaging. They have to have a CRI of at least 80 to get an EnergyStar rating, but most of them are barely above that. You can find 90+ CRI in CFLs, but mostly in daylight simulation bulbs that are 5000K and above. It's too bad, because I think a lot of people would pay for higher CRI bulbs in a wider range of colors.

I personally hate the 2700K light because it's grossly blue deficient. Your eyes can adapt to a wide range of color temperatures while maintaining a visual perception that the light is neutral. Any time the light has a visually obvious color cast, it's a sign that it has a lot more of some colors than others. That applies to the notably warm light from incandescent lamps (and fluorescent lights that try to mimic them) as much as it does to 641 fluorescent lights that have a nasty green tint. You may be able to find high CRI 2700K lights, but that just means that they're doing a good job of mimicking blue deficient incandescent light, not that they're giving truly accurate color rendition.

FWIW, high color temperature is typically more efficient because it most closely matches the sensitivity of our eyes, not because it's letting through more raw blue light from the mercury spectrum. Basically, our eyes have evolved to be most sensitive to wavelengths that are strongest in natural daylight (green and yellow) and less sensitive to colors that are weaker in natural daylight (extreme blue and extreme red). Ratings of lighting efficiency take that sensitivity into account, so daylight balanced light is naturally more efficient than warmer light is.

Comment Re:Visually Efficient? (Score 1) 51

I tried doing that with Fluorescents and realized it gave me headaches.

Make sure you get good quality, high CRI fluorescent lights. A lot of what people don't like about fluorescent lights is the poor quality light, which is sad, because better quality ones are available. You should try for a CRI above 90, and settle for one between 80 and 90. Most linear fluorescents have a CRI rating on the packaging, but CFLs usually don't. You can find high CRI CFLs, but mostly in daylight rather than soft white.

Comment Hold it right there (Score 5, Informative) 51

When to comes to offering warm yet visually efficient lighting, LEDs have a long way to go.

Stop right there. Have these people used recent LED lighting? I just upgraded some lights in my house to LEDs, and they're great. They're at least as good as the LED tubes they replaced, and that's at just over 100 lumens/watt. There are a lot of low quality LEDs out there, but the good ones are already very good indeed.

Comment Re:More than 150? Seriously? (Score 1) 217

It isn't really the right terms for the auction anyway. The company sending you mail should have to start its bidding at the cost of delivering the mail, which is what the postage covers, while your bidding should start at the price of not delivering the mail (e.g. sorting it into a recycling bin and sending it to the recycling plant), which is the alternative they should be considering. Since not delivering is going to be a lot cheaper than delivering, the target of unwanted mail should have an advantage.

Comment Re:More than 150? Seriously? (Score 1) 217

Only first class mail gets forwarded after a change of address, but junk mail companies can and do check the change of address information and update their databases. The last time I moved, a whole bunch of my junk mail followed me. That includes organizations I used to belong to who keep sending me letters about the need to re-join.

Comment Re:No contest, surely. (Score 4, Informative) 405

No, the Post Office does not get $100 million per year in funding. It is legally required to provide certain services at no cost to the recipients, and Congress appropriates money to make up for the costs. In any case, that's a drop in the bucket compared to the total cost of running the Post Office, not a massive subsidy.

And then there are all the ways that the Post Office is required to subsidize other people. They're required to deliver mail to the whole country at a fixed cost, rather than charging different rates according to the actual cost of delivery or refusing to deliver to out-of-the-way places that aren't cost effective. They have to deliver mail for Congress for free, which many Congresspeople abuse. The Post Office is actually very efficient.

Comment Re:All of the above or the public sector in genera (Score 1) 405

We have set the bar far too low for taking money from someone who has earned it and giving to someone who has done nothing except cry about how they need it.

Great. Let's start by taking businesses away from people who inherited them and give them to the employees. Or was that not what you had in mind?

Slashdot Top Deals

If God is perfect, why did He create discontinuous functions?

Working...