The article being quoted clearly states that these cells require concentrated sunlight -- this is true of all thin-film high-TSE cells.
No, the article clearly states that the efficiency is measured at 20 suns concentration. They'll work just fine at lower concentrations, or with no concentration at all, but at a slightly reduced efficiency. Furthermore, the vast majority of thin-film, high-efficiency multijunction solar cells that have ever been manufactured were designed to operate without concentration and are currently circling the globe on various spacecraft.
So basically you can't mount them on the roof, you'll get no power at all.
Not true at all. As I said, you'll lose a few efficiency points, and without the 20X concentration the power output will be further reduced by (surprise, surprise) a factor of 20, but they'll still produce power. But then, why wouldn't you just mount the concentrator on the roof along with the cells?
At any rate, while they talk about roof-mounting these cells, they were ultimately developed with DARPA funding and the military has various uses in mind for them (though the folks at U-Delaware are apparently talking to Dow about commercializing these for the rest of us a few years down the road).
What matters to me: Do those new cells finally "produce" more energy during their life than they required during manufactoring?
What do you mean "finally"? They always have, though nowadays they recover the energy used in their production much faster than they used to. A few years to recovery is typical, and you really have to be trying to make it more than a decade. By contrast, the solar panels themselves are waranteed for 20+ years and thought to have useful lifetimes of 30+ years.
...cover the front of solar cell with deep, open, honeycomb-shaped, reflective walls (e.g. Aluminum or silver) grid? That would effectively act as a light trap
That's a pretty standard design feature in modern solar cells, though typically they use pyramids rather than honeycombs. It isn't practical to do on all solar cells, but nearly every monocrystalline silicon solar cell produced on the planet over the last 10-20 years has had this feature.
Its 20 years since I looked into solar cells in my engineering job, but the figure quoted above must be close to theoretical maximum because solar cells amount to a forward biased diode and can never get to 50% efficiency
The theoretical maximum efficiency for crystalline silicon solar cells is about 29%. However, these solar cells are not made from crystalline silicon. Not only that, they are essentially three different solar cells stacked on top of one another, each optimized for a certain part of the visible spectrum and transparent to the part of the spectrum the cells below it are sensitive to. If you had an infinite number of semiconductor materials, each with a different bandgap energy somewhere in the solar spectrum, and used them to make a "stacked" solar cell like this one the theoretical maximum efficiency would be more like 88%.
they also have poor temperature performance which falls off rapidly as they get hotter, so enclosing them and reflecting more sunlight onto them is exactly the wrong thing to do, they run most efficiently when cool.
Thermal performance is a function of open-circuit voltage (the higher the voltage, the lower the thermal degradation); these cells have rather high open-circuit voltages and won't suffer from the same amount of degradation as silicon cells. The higher efficiency also means that fewer photons are being converted to heat, which should help the cells run cooler. As for "enclosing" them, some sort of packaging is required if the cells are to withstand the outdoor environment. Standard silicon cells packaged in conventional modules lose 10-12% of their potential production in hot areas like the desert southwest, and less elsewhere. The cells discussed in this article will theoretically lose less, but since they're designed to operate under concentrated sunlight (which plays a role in the high efficiency) they will require some sort of active or passive cooling regardless. It's a well established mode of operation for solar cells that are designed for it.
A lot of solar cells require a certain minimal light threshold before they start producing energy, and for reallife application, a lower threshold matters more than a few percent more of peak efficiency.
For conventional silicon solar cells, the threshold you speak of is somewhere down around indoor light levels (which are less than 10% of outdoor light levels on a bright sunny day -- don't trust your eyes on that, they have a logarithmic response to light intensity). Thin film solar cells like amorphous silicon and the ones discussed here won't have that problem (which is why amorphous silicon cells are used in solar calculators), but at those light levels a rooftop of solar cells will barely generate enough power to switch the inverter on and get power flowing into the house. In other words, the inverter is going to be the limiting factor here, and the intensity threshold on the solar cells is moot.
IOW efficiency is a function of among others light intensity
Above the threshold, efficiency is approximately constant (to be more accurate, it is a very weak, slightly nonlinear function of light intensity). If you model a solar cell assuming that efficiency is not a function of light intensity at all, the error in your calculation will be pretty inconsequential.
I wanna know why when they test new airplanes they have an escape hatch that you can jump out and parachute to safety but in the production models this feature is removed.
And everyone in the plane is trained to use parachutes and the hatch. The reason they have it on test flights is because of the nature of test flights -- in essence, nobody really knows if the plane will actually fly until it actually flies.
Would it be that hard to have a parachut under the seat and have everyone bail out if the plane starts going down?
In general, planes don't just "start going down" -- in fact, I can't even think of one aside from aircraft that were shot down. The vast majority of plane crashes occur at takeoff or landing; once you've made it to an altitude where people could safely parachute, there's very little that will cause it to crash in spectacular Hollywood fashion. Bombs or sudden structural failures can, but then the plane disintigrates so fast that nobody has time to strap on a parachute and jump to safety, or the structural failure happens in a manner that it would be far more dangerous to get up and move around than it would to stay strapped in your seat (think Hawaiian Airlines when the roof ripped off). In a deliberate crash, either by a suicidal pilot (EgyptAir) or a hijacker (any of the 9/11 flights) you'd never get an opportunity to use a parachute -- the plane would either be diving in a manner that you'd couldn't get up and walk to the door, or hijackers would prevent you from doing so. In the case of other types of failure, the plane won't simply fall out of the sky, it will glide gently for a long, long time, and it's virtually guaranteed that the pilot will be able to land it with fewer injuries and fatalities than you'll have if 200 untrained parachutists jump out of the plane at an altitude where they're likely to pass out (not to mention that all the passengers will be scattered over hundreds or thousands of square miles, many of them likely landing in trees or water and requiring immediate assistance).
This reminds me a bit of the floating seat cushions they give you. I suppose it's nice to have them in the event of a "water landing," as they like to say, but I've read that nobody has ever survived a water landing in a commercial aircraft. I don't know if that's true, but it's certainly believable -- the pilot has no way of braking on water or skipping over its surface to burn off energy, which makes for an incredibly sudden and violent landing -- and I can't think of a water landing with survivors off the top of my head. I suppose you could argue that would be a good time to have a parachute, but then you're talking about a search over thousands of square miles of water, most likely in an area that would take a long time for rescuers to reach (otherwise the pilot could probably have reached land). You likely wouldn't have any survivors then, either.
Seems that some lives saved would be better than absolutely no lives saved. Or at least they tried.....
It's such a risky proposition that I can't imagine a pilot would ever think he'd save more lives by ordering a parachute evacuation than by trying to land. And if you push a wheelchair-bound 80-year-old lady with no parachute experience out of a plane traveling 300 mph, can you really say you're trying to save her life?
The print article that TFA links to seems to suggest that, but I could swear that in the audio they aired yesterday morning the inventor said the current system uses 2D images. IIRC, the inventor said 3D images are planned for the next generation machine and are expected to help reduce the hiss. But IMNRC (I may not recall correctly)....
Silly me -- it's right there in the summary: 3D images are next generation and expected to help reduce hiss.... That's what I get for posting before coffee.
This system takes an image of the entire disk surface in one pass, with no moving parts. That image is then processed to construct a 3D model of the surface, and that model can then be processed to follow the groove track, much like the laser-based system physically scans the disk surface.
The print article that TFA links to seems to suggest that, but I could swear that in the audio they aired yesterday morning the inventor said the current system uses 2D images. IIRC, the inventor said 3D images are planned for the next generation machine and are expected to help reduce the hiss. But IMNRC (I may not recall correctly)....
I don't know what slashdot is coming to, this is a total dupe! OK, so that story is from 2005, so what?
That's really similar to what the NPR story described, but AFAICT it's a different project performed by different people and wasn't thrown together in an evening (as the end of the page you linked to says that project was). FWIW.
and don't let me get started on the tech's that end up going to your houses, it's like they just don't care who they hire
Last time I had a tech visit my house he needed the customer service department to handle something for him. Apparently Comcast doesn't give its techs a priority number to call, because he called exactly the same number I do and went through the same voice menu that I do. While he was going through the same wait on hold that I do, he explained that the area he lives actually has a choice between Comcast and Charter, and that he chose Charter without even giving it a second thought.
I have to say that I was pretty impressed with this particular tech. Despite customer service telling him to move on to his next appointment and let me call back to finish fixing the problem myself, he insisted on staying until I was up and running again. He even borrowed my phone (while he was on hold on his own phone) to call his next two appointments to let them know he was running late. Haven't had an experience quite like that since....
Not to be a smart ass, but have you heard of 2-story homes?
With odd roof shapes, even a ranch home can have a limited amount of south-facing roof.
True, and not all homes have south-facing roofs. However, I've been involved in the solar industry for over a decade and have yet to meet the owner of a single-family home that seriously pursued solar power and gave up because the panels wouldn't fit on the roof. It wouldn't surprise me in the least if there's one out there somewhere, but it certainly isn't an issue that's keeping anybody up at night. In fact, there's a sizeable portion of the industry that believes solar cell efficiency is irrelevant and all that matters is cost (and many of those folks are quite experienced in installing solar systems in single-family homes).
Of course, a key element of properly sizing a PV system that a lot of people miss is that it's cheaper to upgrade lighting and appliances to high-efficiency models than it is to buy extra solar panels to power the devices most folks already have in their homes. As a result, solar-powered homes typically use significantly less energy than an equivalently sized, conventially powered home. That, of course, further reduces the need for roof space. Look at a few photos of solar-powered homes -- even those that have multiple stories -- and you'll see that it is rare that the entire roof is covered with solar panels.
Finally, until solar power efficiency improves there will be plenty of people who won't have enough roof space to get back their ROI on the investment and thus solar power won't be a popular option until 2 things happen; the panels cost less and are more efficient in coverting light into electricity.
Agree on cost -- right now it's about 2.5x more expensive than the average grid rate in California -- but you're dead wrong about roof space. Using the least efficient cells available a 10 kW PV system will require about 1600 square feet of roof space, which a home large enough to need a 10 kW system would almost certainly have available. Using cells of average efficiency reduces that to less than 1000 square feet, and using the highest efficiency cells brings it down to about 600 square feet. And not only do the cells cost about the same per watt regardless of efficiency, giving you plenty of flexibility on how much roof space you use, you can cut those areas in half for a typical home.
Now if they can only bring back the old "reasonable and prudent" daytime speed limits, also in defiance of the federal government...
Montana's "reasonable and prudent" speed limits were never in defiance of the federal government. They ended in 1974 with the establishment of the national maximum speed limit and were reinstated in 1995 when the national maximum speed limit was repealed by Congress. According to Wikipedia, Montana established a speed limit in 1999 after the Montana Supreme Court reversed a speeding conviction on the grounds that ticketing drivers for speeding when there's no numerical speed limit violates the due process clause of the Montana Constitution, which in effect left Montana with no speed limit whatsoever.
Second, because there are only a limited number of visas to go around, there are many who would apply for a H1-B "just in case" (via the bodyshop route). So it's becoming more of a good-to-have credential that you can show to a potential employer, rather than a legal necessity for working in the US.
Um, no. An individual cannot apply for an H1-B visa, only the sponsoring employer can. That is, you have to find a job before the visa application is submitted by your potential employer. Once you have the visa it is valid only for work with the sponsoring employer, so it is useless as a "good-to-have credential" in finding other work -- if you want to change jobs, your new employer has to get you a new visa.
As for the "bodyshop" route, the H1-B is intended for "specialty occupations" that require at least a 4-year degree, and while "bodyshops" (I assume you mean what most Americans call temporary empolyment agencies) certainly do exist for such occupations, they are the exception rather than the rule. Furthermore, while I'm aware of no provisions prohibiting temp agencies from sponsoring H1-B visas, I rather suspect that for most positions they would have a difficult time making a successful case for one (though I could be wrong). Plus, given the fees charged for a visa application and the nature of the temporary employment industry, I suspect they would have to be pretty desperate before they would consider sponsoring H1-Bs.
Two papers I wrote as a phd student are now behind pay for access portals, where they charge $30 for a single copy, or a subscription.
Do I get a penny of this? Nope, and do I get free access as the Author? Nope.
Nor are you entitled to that, regardless of whether you hold the copyright. The copyright only applies to the text, tables, and figures you submitted, not the typeset and printed pages that the journal produces. Authors of books and magazine articles often retain the copyrights to their works, but many of them don't get free copies of their books or articles. That said, many academic journals provide authors with a certain number of reprints. Apparently not the one you were published in....
Did they ask for my permission? Nope.
Sure they did, and you granted it when you agreed to let them publish it. You did give them permission to publish it, didn't you? If you wanted to get paid for it, you should have submitted it to a publication that pays its authors. Academic publications generally don't do that, though, and I suspect you knew that when you chose to publish there. Presumably, the value you received from publishing without compensation was greater than the value you would have received from publishing elsewhere or not publishing at all -- otherwise, why did you let them publish it?
Its the standard way papers are distributed in the academic world. I think it's unfair as it stands, although I recognise they have some need to recoup their storage/indexing costs.
Why is it unfair? Academic journals have a small audience interested in reading their publications and ethical considerations that prohibit them from accepting advertising. Furthermore, they have an enormous pool of authors who are willing to provide them content without compensation (because for those authors, publishing is a means to an end, not a living unto itself). They have absolutely no incentive to pay you or give you anything for free, and a rather large disincentive to do so. I happen to think there are a lot of things wrong with academic publishing, but this is not one of them. The more they have to give to their authors, the fewer papers they can afford to publish and the harder it will be to get published. If your graduation is delayed because you're having a hard time getting published, that's going to cost you a whole lot more than you would ever get in compensation for your paper.
As for the true scope of the permissions you granted them, if they published your article then I'm certain you and/or your co-author(s) signed something granting them permission to do so (or otherwise provided legally binding consent). If not, they had no right to publish the article in the first place. I also suspect that if you read the fine print wherever your consent is recorded that you granted them all rights to the article, as academic journals typically require. That means that not only did you give them permission to publish the article, but you also assigned the copyright on the article to the publisher. That means they can do with it as they wish, including publishing it elsewhere without your permission. It also means that if you ever want to re-publish the article elsewhere (even your own dissertation), you need to ask the original publisher for permission even though you are the author. Don't like it? Don't assign them all rights. Sure, that means they probably won't publish it, but when they've got 10 other people willing to take your place in the journal why should they care?
By the way, it's not just academic authors who have to deal with this -- there are a fair number of mainstream publications that will only buy all rights. Of course, they buy them, meaning the authors are monetarily compensated, but then they're dealing with professional writers and attempting to attract an entirely different sort of author than academic journals are. Magazines with high-quality articles, of course, tend to pay well and agree to buy one-time publication rights only because that's what attracts the best writers, but the academic market is a completely different story.
Polymer solar cells have already been made, there are some efficiency issues but they are incredibly cheap. The problem with them is that they disintegrate very quickly. As far as I understood, this was the real problem with conducting polymers of all sorts (the thiophenes, etc.) as far as I know. Anyone know the current status of this?
There's been a little progress -- within the last year somebody announced that he developed a polymer solar cell that might be able to last 5 years in the field. I don't recall what he did to get the additional lifetime, but most polymer cells are thought to have lifetimes no greater than a year or two (and some can't even make it that long in the laboratory, let alone baking in the sun under UV rays).
But right now, that's just one of many issues that polymer cells face. You mentioned efficiency issues, and I'm not sure that having a more conductive plastic will provide a significant boost. Polymer solar cells work by absorbing photons to create excitons, which are similar to the electron-hole pairs you see in silicon and other semiconductors. However, with an exciton the electron and the hole are tightly bound to one another and cannot move independently, so they act as a single particle. The trick is to move the exciton to a junction between two plastics of differing work function, where the electron and hole can be separated by electrostatic force and can then be used to produce an electric current. The problem is, you're lucky if you can move the exciton more than a few tens of nanometers before it relaxes. This has resulted in all sorts of weird device structures designed to minimize the distance the excitons must travel to reach the junction. Increased conductivity will not necessarily allow excitons to travel farther -- in fact, in silicon increasing conductivity often reduces the distance electrons and holes can travel -- so it won't necessarily help with this problem. It may help with other issues, though, I don't know.
I hate to be a warmonger here, but this stuff could probably be used in military applications as well, probably for night ops and the like. A modern day ninja outfit with this stuff comes to mind, or if the stuff could be tweaked to not only absorb light, but radar as well.
If it reflects virutally nothing, I wonder how it dissipitates heat, or if heat is even a factor in this.
It doesn't absorb anything. It's simply several layers of silicon dioxide nanotubes whose index of refraction is controlled by their arrangement. In other words, it's a multilayer antireflection coating. It won't work with radar any more than regular old silicon dioxide or other typical antireflection coatings will.
Complete fabrication. Porn is a large industry but not larger then the Theatric movie release industry. The 12-15 number is based on interviews AVN did then re-enforced in Frobes for mentioning it.
Yes. According to a bunch of adult industry folks, the real figure is more likely $400-500 million annually, which makes much more sense than $12-15 billion if you believe the guy from the BoingBoing post who says $216 million is spent making porn movies each year. The $12-15 billion number includes the entire adult entertainment industry -- strip clubs, sex toys, etc. in addition to porn movies, but keeps getting pushed as the size of the "porn industry".
This reminds me of an attorney I once knew who worked as a prosecutor for a major U.S. city. The city included several universities, and whenever one of the university police forces turned over a case to her there was a far higher than average chance she would have to drop it because of the lack of professionalism of the police. Generally it was because proper procedures were not followed, so evidence was either (a) missing or (b) inadmissible in court, though I do seem to recall her mentioning a case where someone was arrested for doing something perfectly legal. I can't recall any stories of gross misconduct like this one, though.
Except that, like, no one has been killed in the name of atheism. Ever.
I agree with you on most points -- I see no reason to believe that Stalin or Hitler ever killed anybody in the name of atheism. Mao, on the other hand, routinely dispatched his Red Guard to religious sites to destroy them and kill religious people for no reason other than that they were religious. Granted, it was part of a larger plan, but isn't that always the case? Even the Crusades weren't just about killing Muslims, and during the first Crusade in particular Christian mercenaries massacred huge numbers of Jews and Orthodox Christians on the way to the front lines.
Mind you, I'm no fan of religion, but I think if you were to devise a litmus test to determine whether a death was "in the name" of some religion (including atheism) you would either have to count a considerable number of deaths against atheism or seriously reduce the number of deaths you attribute to religion. No doubt you would still have considerably fewer deaths attributed to atheism, but then atheists have historically existed in much smaller numbers and largely without the means to kill "in the name" of atheism. Atheists can be just as sane or insane as religious people, and regardless of the justification for violence I see no compelling reason to believe that atheists, given the numbers and means, would be any less violent than the religious.
Bain Capital is a private equity firm that was founded by Mitt Romney, outgoing governor of Massachusetts and 2008 presidential hopeful. (Last year they tried to buy the entire National Hockey League.) I guess we can't really know how meaningful that is until the 2008 election is upon us, but a presidential candidate with his own network of radio stations is courting controversy to say the least.
Like nearly all technologies, it's benign. It's up to the user to make it good or bad.
While I agree the technology itself is benign, it seems to me the user doesn't really have much control over good or bad. The user can choose be tracked or not, and that's about it. Whether it's good or bad for the user depends on who makes use of the tracking information and why, and that is totally beyond the user's control. Your own comment gave examples of that: Stalkers, followups from the professor, and subpoena-happy attorneys are all beyond the user's control.
Certainly the user has a choice about whether to expose him- or herself to all of that, but he or she is at the mercy of the other users (and the occasional non-user, like an attorney) to make it a good or bad experience.
Reminds me of the folks who have a problem with LaTeX, but blame the text editor because that's where the button they clicked to run LaTeX is. Makes about as much sense as blaming your television set because there's nothing good on TV....
"It's a lot cheaper to buy high-efficiency appliances than it is to buy enough PV to power low-efficiency ones."
Yes, and no. Within reasaonable limits, any size solar array will pay itself off in pretty much the same amount of time in energy savings.
I think you miss my point. A 3 kW PV array might cost $24,000 while a 2 kW array might cost only $16,000. Suppose the 3 kW system will meet your needs without you replacing any appliances, but the 2 kW system will meet your needs if you replace your lighting and major appliances with high-efficiency versions. If the lighting and appliance replacement costs less than $8,000 -- the difference in cost between the two systems -- it is more cost-effective to buy the appliances and the 2-kW system than it is to buy the 3-kW system. Typically, this is exactly the case and the homeowner can spend, say, $4,000 on appliances and $16,000 on PV -- a total of $20,000 -- instead of $24,000 on PV. Unless you're able borrow money for free, the smaller system is the cheaper one no matter how you slice it -- you get all the energy you need for $20,000 instead of $24,000.
And I do understand that if you assume all of the energy is used the break-even points will be similar, but what you're saying amounts to throwing money at excess energy consumption instead of simply reducing consumption. If you disagree, look at it this way: if you borrow $24,000 you can (a) spend it all on PV, or (b) spend $4,000 on appliances, $16,000 on PV, and have $4,000 left over to do whatever you like. Which option do you think gives you the most value?
Slashdot Mirror
The article being quoted clearly states that these cells require concentrated sunlight -- this is true of all thin-film high-TSE cells.
No, the article clearly states that the efficiency is measured at 20 suns concentration. They'll work just fine at lower concentrations, or with no concentration at all, but at a slightly reduced efficiency. Furthermore, the vast majority of thin-film, high-efficiency multijunction solar cells that have ever been manufactured were designed to operate without concentration and are currently circling the globe on various spacecraft.
So basically you can't mount them on the roof, you'll get no power at all.
Not true at all. As I said, you'll lose a few efficiency points, and without the 20X concentration the power output will be further reduced by (surprise, surprise) a factor of 20, but they'll still produce power. But then, why wouldn't you just mount the concentrator on the roof along with the cells?
At any rate, while they talk about roof-mounting these cells, they were ultimately developed with DARPA funding and the military has various uses in mind for them (though the folks at U-Delaware are apparently talking to Dow about commercializing these for the rest of us a few years down the road).
What matters to me: Do those new cells finally "produce" more energy during their life than they required during manufactoring?
What do you mean "finally"? They always have, though nowadays they recover the energy used in their production much faster than they used to. A few years to recovery is typical, and you really have to be trying to make it more than a decade. By contrast, the solar panels themselves are waranteed for 20+ years and thought to have useful lifetimes of 30+ years.
That's a pretty standard design feature in modern solar cells, though typically they use pyramids rather than honeycombs. It isn't practical to do on all solar cells, but nearly every monocrystalline silicon solar cell produced on the planet over the last 10-20 years has had this feature.
Its 20 years since I looked into solar cells in my engineering job, but the figure quoted above must be close to theoretical maximum because solar cells amount to a forward biased diode and can never get to 50% efficiency
The theoretical maximum efficiency for crystalline silicon solar cells is about 29%. However, these solar cells are not made from crystalline silicon. Not only that, they are essentially three different solar cells stacked on top of one another, each optimized for a certain part of the visible spectrum and transparent to the part of the spectrum the cells below it are sensitive to. If you had an infinite number of semiconductor materials, each with a different bandgap energy somewhere in the solar spectrum, and used them to make a "stacked" solar cell like this one the theoretical maximum efficiency would be more like 88%.
they also have poor temperature performance which falls off rapidly as they get hotter, so enclosing them and reflecting more sunlight onto them is exactly the wrong thing to do, they run most efficiently when cool.
Thermal performance is a function of open-circuit voltage (the higher the voltage, the lower the thermal degradation); these cells have rather high open-circuit voltages and won't suffer from the same amount of degradation as silicon cells. The higher efficiency also means that fewer photons are being converted to heat, which should help the cells run cooler. As for "enclosing" them, some sort of packaging is required if the cells are to withstand the outdoor environment. Standard silicon cells packaged in conventional modules lose 10-12% of their potential production in hot areas like the desert southwest, and less elsewhere. The cells discussed in this article will theoretically lose less, but since they're designed to operate under concentrated sunlight (which plays a role in the high efficiency) they will require some sort of active or passive cooling regardless. It's a well established mode of operation for solar cells that are designed for it.
A lot of solar cells require a certain minimal light threshold before they start producing energy, and for reallife application, a lower threshold matters more than a few percent more of peak efficiency.
For conventional silicon solar cells, the threshold you speak of is somewhere down around indoor light levels (which are less than 10% of outdoor light levels on a bright sunny day -- don't trust your eyes on that, they have a logarithmic response to light intensity). Thin film solar cells like amorphous silicon and the ones discussed here won't have that problem (which is why amorphous silicon cells are used in solar calculators), but at those light levels a rooftop of solar cells will barely generate enough power to switch the inverter on and get power flowing into the house. In other words, the inverter is going to be the limiting factor here, and the intensity threshold on the solar cells is moot.
IOW efficiency is a function of among others light intensity
Above the threshold, efficiency is approximately constant (to be more accurate, it is a very weak, slightly nonlinear function of light intensity). If you model a solar cell assuming that efficiency is not a function of light intensity at all, the error in your calculation will be pretty inconsequential.
The screenshots clearly show WinXP, not Vista.
You can identify his OS from a screenshot? If you saw a screenshot of my system you'd swear I run Win2k. I don't.
I wanna know why when they test new airplanes they have an escape hatch that you can jump out and parachute to safety but in the production models this feature is removed.
And everyone in the plane is trained to use parachutes and the hatch. The reason they have it on test flights is because of the nature of test flights -- in essence, nobody really knows if the plane will actually fly until it actually flies.
Would it be that hard to have a parachut under the seat and have everyone bail out if the plane starts going down?
In general, planes don't just "start going down" -- in fact, I can't even think of one aside from aircraft that were shot down. The vast majority of plane crashes occur at takeoff or landing; once you've made it to an altitude where people could safely parachute, there's very little that will cause it to crash in spectacular Hollywood fashion. Bombs or sudden structural failures can, but then the plane disintigrates so fast that nobody has time to strap on a parachute and jump to safety, or the structural failure happens in a manner that it would be far more dangerous to get up and move around than it would to stay strapped in your seat (think Hawaiian Airlines when the roof ripped off). In a deliberate crash, either by a suicidal pilot (EgyptAir) or a hijacker (any of the 9/11 flights) you'd never get an opportunity to use a parachute -- the plane would either be diving in a manner that you'd couldn't get up and walk to the door, or hijackers would prevent you from doing so. In the case of other types of failure, the plane won't simply fall out of the sky, it will glide gently for a long, long time, and it's virtually guaranteed that the pilot will be able to land it with fewer injuries and fatalities than you'll have if 200 untrained parachutists jump out of the plane at an altitude where they're likely to pass out (not to mention that all the passengers will be scattered over hundreds or thousands of square miles, many of them likely landing in trees or water and requiring immediate assistance).
This reminds me a bit of the floating seat cushions they give you. I suppose it's nice to have them in the event of a "water landing," as they like to say, but I've read that nobody has ever survived a water landing in a commercial aircraft. I don't know if that's true, but it's certainly believable -- the pilot has no way of braking on water or skipping over its surface to burn off energy, which makes for an incredibly sudden and violent landing -- and I can't think of a water landing with survivors off the top of my head. I suppose you could argue that would be a good time to have a parachute, but then you're talking about a search over thousands of square miles of water, most likely in an area that would take a long time for rescuers to reach (otherwise the pilot could probably have reached land). You likely wouldn't have any survivors then, either.
Seems that some lives saved would be better than absolutely no lives saved. Or at least they tried.....
It's such a risky proposition that I can't imagine a pilot would ever think he'd save more lives by ordering a parachute evacuation than by trying to land. And if you push a wheelchair-bound 80-year-old lady with no parachute experience out of a plane traveling 300 mph, can you really say you're trying to save her life?
The print article that TFA links to seems to suggest that, but I could swear that in the audio they aired yesterday morning the inventor said the current system uses 2D images. IIRC, the inventor said 3D images are planned for the next generation machine and are expected to help reduce the hiss. But IMNRC (I may not recall correctly)....
Silly me -- it's right there in the summary: 3D images are next generation and expected to help reduce hiss.... That's what I get for posting before coffee.
This system takes an image of the entire disk surface in one pass, with no moving parts. That image is then processed to construct a 3D model of the surface, and that model can then be processed to follow the groove track, much like the laser-based system physically scans the disk surface.
The print article that TFA links to seems to suggest that, but I could swear that in the audio they aired yesterday morning the inventor said the current system uses 2D images. IIRC, the inventor said 3D images are planned for the next generation machine and are expected to help reduce the hiss. But IMNRC (I may not recall correctly)....
I don't know what slashdot is coming to, this is a total dupe! OK, so that story is from 2005, so what?
That's really similar to what the NPR story described, but AFAICT it's a different project performed by different people and wasn't thrown together in an evening (as the end of the page you linked to says that project was). FWIW.
and don't let me get started on the tech's that end up going to your houses, it's like they just don't care who they hire
Last time I had a tech visit my house he needed the customer service department to handle something for him. Apparently Comcast doesn't give its techs a priority number to call, because he called exactly the same number I do and went through the same voice menu that I do. While he was going through the same wait on hold that I do, he explained that the area he lives actually has a choice between Comcast and Charter, and that he chose Charter without even giving it a second thought.
I have to say that I was pretty impressed with this particular tech. Despite customer service telling him to move on to his next appointment and let me call back to finish fixing the problem myself, he insisted on staying until I was up and running again. He even borrowed my phone (while he was on hold on his own phone) to call his next two appointments to let them know he was running late. Haven't had an experience quite like that since....
Not to be a smart ass, but have you heard of 2-story homes?
With odd roof shapes, even a ranch home can have a limited amount of south-facing roof.
True, and not all homes have south-facing roofs. However, I've been involved in the solar industry for over a decade and have yet to meet the owner of a single-family home that seriously pursued solar power and gave up because the panels wouldn't fit on the roof. It wouldn't surprise me in the least if there's one out there somewhere, but it certainly isn't an issue that's keeping anybody up at night. In fact, there's a sizeable portion of the industry that believes solar cell efficiency is irrelevant and all that matters is cost (and many of those folks are quite experienced in installing solar systems in single-family homes).
Of course, a key element of properly sizing a PV system that a lot of people miss is that it's cheaper to upgrade lighting and appliances to high-efficiency models than it is to buy extra solar panels to power the devices most folks already have in their homes. As a result, solar-powered homes typically use significantly less energy than an equivalently sized, conventially powered home. That, of course, further reduces the need for roof space. Look at a few photos of solar-powered homes -- even those that have multiple stories -- and you'll see that it is rare that the entire roof is covered with solar panels.
Finally, until solar power efficiency improves there will be plenty of people who won't have enough roof space to get back their ROI on the investment and thus solar power won't be a popular option until 2 things happen; the panels cost less and are more efficient in coverting light into electricity.
Agree on cost -- right now it's about 2.5x more expensive than the average grid rate in California -- but you're dead wrong about roof space. Using the least efficient cells available a 10 kW PV system will require about 1600 square feet of roof space, which a home large enough to need a 10 kW system would almost certainly have available. Using cells of average efficiency reduces that to less than 1000 square feet, and using the highest efficiency cells brings it down to about 600 square feet. And not only do the cells cost about the same per watt regardless of efficiency, giving you plenty of flexibility on how much roof space you use, you can cut those areas in half for a typical home.
Now if they can only bring back the old "reasonable and prudent" daytime speed limits, also in defiance of the federal government...
Montana's "reasonable and prudent" speed limits were never in defiance of the federal government. They ended in 1974 with the establishment of the national maximum speed limit and were reinstated in 1995 when the national maximum speed limit was repealed by Congress. According to Wikipedia, Montana established a speed limit in 1999 after the Montana Supreme Court reversed a speeding conviction on the grounds that ticketing drivers for speeding when there's no numerical speed limit violates the due process clause of the Montana Constitution, which in effect left Montana with no speed limit whatsoever.
Second, because there are only a limited number of visas to go around, there are many who would apply for a H1-B "just in case" (via the bodyshop route). So it's becoming more of a good-to-have credential that you can show to a potential employer, rather than a legal necessity for working in the US.
Um, no. An individual cannot apply for an H1-B visa, only the sponsoring employer can. That is, you have to find a job before the visa application is submitted by your potential employer. Once you have the visa it is valid only for work with the sponsoring employer, so it is useless as a "good-to-have credential" in finding other work -- if you want to change jobs, your new employer has to get you a new visa.
As for the "bodyshop" route, the H1-B is intended for "specialty occupations" that require at least a 4-year degree, and while "bodyshops" (I assume you mean what most Americans call temporary empolyment agencies) certainly do exist for such occupations, they are the exception rather than the rule. Furthermore, while I'm aware of no provisions prohibiting temp agencies from sponsoring H1-B visas, I rather suspect that for most positions they would have a difficult time making a successful case for one (though I could be wrong). Plus, given the fees charged for a visa application and the nature of the temporary employment industry, I suspect they would have to be pretty desperate before they would consider sponsoring H1-Bs.
Two papers I wrote as a phd student are now behind pay for access portals, where they charge $30 for a single copy, or a subscription.
Do I get a penny of this? Nope, and do I get free access as the Author? Nope.
Nor are you entitled to that, regardless of whether you hold the copyright. The copyright only applies to the text, tables, and figures you submitted, not the typeset and printed pages that the journal produces. Authors of books and magazine articles often retain the copyrights to their works, but many of them don't get free copies of their books or articles. That said, many academic journals provide authors with a certain number of reprints. Apparently not the one you were published in....
Did they ask for my permission? Nope.
Sure they did, and you granted it when you agreed to let them publish it. You did give them permission to publish it, didn't you? If you wanted to get paid for it, you should have submitted it to a publication that pays its authors. Academic publications generally don't do that, though, and I suspect you knew that when you chose to publish there. Presumably, the value you received from publishing without compensation was greater than the value you would have received from publishing elsewhere or not publishing at all -- otherwise, why did you let them publish it?
Its the standard way papers are distributed in the academic world. I think it's unfair as it stands, although I recognise they have some need to recoup their storage/indexing costs.
Why is it unfair? Academic journals have a small audience interested in reading their publications and ethical considerations that prohibit them from accepting advertising. Furthermore, they have an enormous pool of authors who are willing to provide them content without compensation (because for those authors, publishing is a means to an end, not a living unto itself). They have absolutely no incentive to pay you or give you anything for free, and a rather large disincentive to do so. I happen to think there are a lot of things wrong with academic publishing, but this is not one of them. The more they have to give to their authors, the fewer papers they can afford to publish and the harder it will be to get published. If your graduation is delayed because you're having a hard time getting published, that's going to cost you a whole lot more than you would ever get in compensation for your paper.
As for the true scope of the permissions you granted them, if they published your article then I'm certain you and/or your co-author(s) signed something granting them permission to do so (or otherwise provided legally binding consent). If not, they had no right to publish the article in the first place. I also suspect that if you read the fine print wherever your consent is recorded that you granted them all rights to the article, as academic journals typically require. That means that not only did you give them permission to publish the article, but you also assigned the copyright on the article to the publisher. That means they can do with it as they wish, including publishing it elsewhere without your permission. It also means that if you ever want to re-publish the article elsewhere (even your own dissertation), you need to ask the original publisher for permission even though you are the author. Don't like it? Don't assign them all rights. Sure, that means they probably won't publish it, but when they've got 10 other people willing to take your place in the journal why should they care?
By the way, it's not just academic authors who have to deal with this -- there are a fair number of mainstream publications that will only buy all rights. Of course, they buy them, meaning the authors are monetarily compensated, but then they're dealing with professional writers and attempting to attract an entirely different sort of author than academic journals are. Magazines with high-quality articles, of course, tend to pay well and agree to buy one-time publication rights only because that's what attracts the best writers, but the academic market is a completely different story.
Polymer solar cells have already been made, there are some efficiency issues but they are incredibly cheap. The problem with them is that they disintegrate very quickly. As far as I understood, this was the real problem with conducting polymers of all sorts (the thiophenes, etc.) as far as I know. Anyone know the current status of this?
There's been a little progress -- within the last year somebody announced that he developed a polymer solar cell that might be able to last 5 years in the field. I don't recall what he did to get the additional lifetime, but most polymer cells are thought to have lifetimes no greater than a year or two (and some can't even make it that long in the laboratory, let alone baking in the sun under UV rays).
But right now, that's just one of many issues that polymer cells face. You mentioned efficiency issues, and I'm not sure that having a more conductive plastic will provide a significant boost. Polymer solar cells work by absorbing photons to create excitons, which are similar to the electron-hole pairs you see in silicon and other semiconductors. However, with an exciton the electron and the hole are tightly bound to one another and cannot move independently, so they act as a single particle. The trick is to move the exciton to a junction between two plastics of differing work function, where the electron and hole can be separated by electrostatic force and can then be used to produce an electric current. The problem is, you're lucky if you can move the exciton more than a few tens of nanometers before it relaxes. This has resulted in all sorts of weird device structures designed to minimize the distance the excitons must travel to reach the junction. Increased conductivity will not necessarily allow excitons to travel farther -- in fact, in silicon increasing conductivity often reduces the distance electrons and holes can travel -- so it won't necessarily help with this problem. It may help with other issues, though, I don't know.
I hate to be a warmonger here, but this stuff could probably be used in military applications as well, probably for night ops and the like. A modern day ninja outfit with this stuff comes to mind, or if the stuff could be tweaked to not only absorb light, but radar as well.
If it reflects virutally nothing, I wonder how it dissipitates heat, or if heat is even a factor in this.
It doesn't absorb anything. It's simply several layers of silicon dioxide nanotubes whose index of refraction is controlled by their arrangement. In other words, it's a multilayer antireflection coating. It won't work with radar any more than regular old silicon dioxide or other typical antireflection coatings will.
Complete fabrication. Porn is a large industry but not larger then the Theatric movie release industry. The 12-15 number is based on interviews AVN did then re-enforced in Frobes for mentioning it.
Yes. According to a bunch of adult industry folks, the real figure is more likely $400-500 million annually, which makes much more sense than $12-15 billion if you believe the guy from the BoingBoing post who says $216 million is spent making porn movies each year. The $12-15 billion number includes the entire adult entertainment industry -- strip clubs, sex toys, etc. in addition to porn movies, but keeps getting pushed as the size of the "porn industry".
This reminds me of an attorney I once knew who worked as a prosecutor for a major U.S. city. The city included several universities, and whenever one of the university police forces turned over a case to her there was a far higher than average chance she would have to drop it because of the lack of professionalism of the police. Generally it was because proper procedures were not followed, so evidence was either (a) missing or (b) inadmissible in court, though I do seem to recall her mentioning a case where someone was arrested for doing something perfectly legal. I can't recall any stories of gross misconduct like this one, though.
Except that, like, no one has been killed in the name of atheism. Ever.
I agree with you on most points -- I see no reason to believe that Stalin or Hitler ever killed anybody in the name of atheism. Mao, on the other hand, routinely dispatched his Red Guard to religious sites to destroy them and kill religious people for no reason other than that they were religious. Granted, it was part of a larger plan, but isn't that always the case? Even the Crusades weren't just about killing Muslims, and during the first Crusade in particular Christian mercenaries massacred huge numbers of Jews and Orthodox Christians on the way to the front lines.
Mind you, I'm no fan of religion, but I think if you were to devise a litmus test to determine whether a death was "in the name" of some religion (including atheism) you would either have to count a considerable number of deaths against atheism or seriously reduce the number of deaths you attribute to religion. No doubt you would still have considerably fewer deaths attributed to atheism, but then atheists have historically existed in much smaller numbers and largely without the means to kill "in the name" of atheism. Atheists can be just as sane or insane as religious people, and regardless of the justification for violence I see no compelling reason to believe that atheists, given the numbers and means, would be any less violent than the religious.
Bain Capital is a private equity firm that was founded by Mitt Romney, outgoing governor of Massachusetts and 2008 presidential hopeful. (Last year they tried to buy the entire National Hockey League.) I guess we can't really know how meaningful that is until the 2008 election is upon us, but a presidential candidate with his own network of radio stations is courting controversy to say the least.
Like nearly all technologies, it's benign. It's up to the user to make it good or bad.
While I agree the technology itself is benign, it seems to me the user doesn't really have much control over good or bad. The user can choose be tracked or not, and that's about it. Whether it's good or bad for the user depends on who makes use of the tracking information and why, and that is totally beyond the user's control. Your own comment gave examples of that: Stalkers, followups from the professor, and subpoena-happy attorneys are all beyond the user's control.
Certainly the user has a choice about whether to expose him- or herself to all of that, but he or she is at the mercy of the other users (and the occasional non-user, like an attorney) to make it a good or bad experience.
Reminds me of the folks who have a problem with LaTeX, but blame the text editor because that's where the button they clicked to run LaTeX is. Makes about as much sense as blaming your television set because there's nothing good on TV....
"It's a lot cheaper to buy high-efficiency appliances than it is to buy enough PV to power low-efficiency ones."
Yes, and no. Within reasaonable limits, any size solar array will pay itself off in pretty much the same amount of time in energy savings.
I think you miss my point. A 3 kW PV array might cost $24,000 while a 2 kW array might cost only $16,000. Suppose the 3 kW system will meet your needs without you replacing any appliances, but the 2 kW system will meet your needs if you replace your lighting and major appliances with high-efficiency versions. If the lighting and appliance replacement costs less than $8,000 -- the difference in cost between the two systems -- it is more cost-effective to buy the appliances and the 2-kW system than it is to buy the 3-kW system. Typically, this is exactly the case and the homeowner can spend, say, $4,000 on appliances and $16,000 on PV -- a total of $20,000 -- instead of $24,000 on PV. Unless you're able borrow money for free, the smaller system is the cheaper one no matter how you slice it -- you get all the energy you need for $20,000 instead of $24,000.
And I do understand that if you assume all of the energy is used the break-even points will be similar, but what you're saying amounts to throwing money at excess energy consumption instead of simply reducing consumption. If you disagree, look at it this way: if you borrow $24,000 you can (a) spend it all on PV, or (b) spend $4,000 on appliances, $16,000 on PV, and have $4,000 left over to do whatever you like. Which option do you think gives you the most value?