Solar Thermal Towers And How They Work
A Solar Thermal Tower runs on the thermal law that hot air rises. Basically the way a thermal tower works is very similar to what would happen if you combined a convection oven with a chimney.
A solar thermal tower has three main parts. The tower, the collector, and the turbine. The more prominent is the tower itself. The tower is almost like an exhaust. Around the tower is a huge collection area. The collection area is usually a covering of very thin film polymer sheeting, glass, plexiglass or lexan. The sun hits the collection material, heating the area underneath. As this air gets warmed up to around 100 deg, the air looks for an escape route. The heated air can reach speeds of up to 35 mph when exiting out of the thermal tower. If you put wind turbines inside the tower so that the heated, escaping air is making them spin, the heated air can be used to generate electricity.This type of power plant also works at night. With no modification, the sun not only heats up the air in the collector area, but it also heats up the ground, so at night when the sun goes down, the ground releases its heat which still produces the air current to make the turbines generate electricity. Because of the obvious absence of heat, the power output won’t be quite as much as during daylight hours. However if water is piped through the collection area, it will hold and transfer more heat with greater efficiency when the sun goes down.One of the main drawbacks to this type of power generation is the need for size. The more area for collection, the greater the amount of heated air, the more power is generated. The same adjustments in output are made with the change in tower height and diameter. The more air you can heat and push through the chimney, the faster you can spin turbines and the more power the can generate. This means more land will be needed and taller stacks. The best types of land for these power centers seem to be desert or otherwise lower valued land.
Archive for December, 2007
Latest Mac OS X 10.5.1 build fixes Finder data loss issue
Apple Inc. on Monday continued to pound away at its first maintenance and security update to the recently released Mac OS X 10.5 Leopard operating system, issuing a new test build to developers that fixes the much publicized Finder data loss issue.
People familiar with the ongoing testing process for Mac OS X 10.5.1 Update say the new build, labeled Mac OS X 10.5.1 build 9B16, was accompanied by a note to developers that specifically mentions a Finder-related fix affecting files that are moved between directories.
It was widely reported earlier this month that Leopard’s Finder is affected by a glaring bug in its directory-moving code, which could lead to horrendous data loss if a destination volume disappears while a move operation is in progress.
Those people familiar with pre-release builds of Mac OS X 10.5.1 also added that the software update will deliver an enhancement to Leopard that will allow Apple’s Software Update and installer applications to make revisions to application files which may have been moved outside their designated “Applications” directory on Leopard volumes.
As was the case with build 9B13, which was released for private testing last Monday, Apple is reportedly asking that its developers test the latest build broadly, paying particular attention to Time Machine, Mail, iCal, Back To My Mac, Bonjour, AirPort, gaming graphics, networking and the Finder.
Mac OS X 10.5.1 is expected to be released as a free update within a few weeks’ time.
Why do Apple customers care so much?
The question inevitably comes up when I meet people and they learn I write about Apple for a living: “So, what’s that like?”
I usually answer, “It’s crazy.” There perhaps has never been a more interesting time to write about Apple and its growing impact on the computer, telecommunications, and music worlds. Unfortunately, it also means that I have to witness (and sometimes join) a daily descent into a pit of mudslinging. Their size and degree of organization can be debated, and it’s usually overstated. But there is no question that Macintosh users are by far the most passionate advocates for their products in the technology industry. And while such passion is remarkable and even moving, it can also be terribly disturbing.
Take a recent story I wrote, “Problems with the Mac promised land.” The story was about how Apple sells the Mac as a computer that “just works” in its ubiquitous ad campaign comparing the Mac and the PC. But the Mac, like anything, is not immune to problems from time to time. Anyone who has followed Apple over the last couple of months knows that Leopard early adopters have run into a few issues, which we covered here and here.
Nothing in the article suggested that Mac users are revolting against Leopard, or that serious Leopard glitches have knocked the Mac user base offline, or anything even close to that effect. The majority of the discussion in the Talkback section, however, descended into the usual Mac vs. PC flame war. In addition to attacking each other, several people took me to task, saying that since they had never had a problem with their Mac or with their Leopard installation, I was clearly manufacturing problems as part of a sinister plan to either attack the Mac and put Apple out of business at the bidding of Microsoft, or through some naked self-interest of both myself and CNET to generate page views.
This happens just about every time I write about Apple. In fairness, that aggressive behavior is not indicative of Mac users as a whole. But that very noisy, hardcore crowd distorts the issues and inflames the discussion, to the point where a rational look at Apple and its products becomes a quest to decide The World’s One True Religion, which never seems to work out so well in the real world.
I think the roots of this zealotry go back to a time when Apple was on the ropes financially and someone who worked on a Mac was ridiculed by other computer users. Ten years ago, Mac users in the corporate world were viewed as rubes playing with “toys” not suitable for getting real work done, and there were plenty of people ready to remind the Mac community in not-so-subtle ways that the revolution promised in the 1980s by the original Macintosh was being fulfilled by Microsoft software. Apple’s response was to change the tone of the conversation, and it deliberately chose a spiritual motif for its message with the work started by Guy Kawasaki in the mid-1990s. Kawasaki originally worked at Apple in the mid-1980s in marketing, and was part of the team that introduced the Macintosh to the world before leaving in 1987.
When Kawasaki rejoined Apple in 1995, the company was probably at its lowest point. On his Web site, Kawasaki describes his role at Apple in the mid-1990s by saying, “My job on this tour of duty was to maintain and rejuvenate the Macintosh cult.” There was a dedicated group out there who still believed in the Mac and its promise as an alternative to Windows, but they weren’t organized, and their morale was low.
In an inteview this week, Kawasaki recalled signing up 44,000 hardcore Mac users in 1995 on a listserv named, quite appropriately, “EvangeList.” “All I would do is disseminate good news,” Kawasaki said. He wanted his listserv to be a counterpoint to the torrents of bad news about the Mac, exemplified by a 1996 BusinessWeek cover story about Apple titled, “The Fall of an American Icon.” For its cover art, the magazine placed an Apple icon in front of a black, funereal background.
Kawasaki’s idea was to give Mac users hope, that they were not alone, and that they were on the right side of history. Hope is a powerful thing to someone at the end of their rope, and while that’s perhaps overstating it a bit, that’s how many Mac users felt in those years. “It’s almost like a religious experience in that you feel like you have to tell everyone you know in an effort to ’save them.’ It’s crazy, and I never understood those people but now I am one,” said Doug Otto, a News.com reader, vice president of systems engineering for Govstar and a Sacramento, Calif., resident.
The trouble is that most people don’t like cults; they associate them with Charles Manson or Red Sox fans. Sure, you may believe you have all the answers. But there are a lot of people who automatically tune out the incessant preaching of a zealot. With the rise of the Internet, it became much easier to preach that gospel far and wide and anonymously. “Like anything people are passionate about–sports, politics, religion–there are going to be some people who are goofy about it and don’t have that thing in their brain that tells them they’ve stepped over the edge from ‘fan’ to ‘fanatic’,” said John Moltz, the editor of Crazy Apple Rumors Site and perhaps the best source of comic relief in the Apple universe.
Since it’s a two-party world, however, many of those evangelists combined their love for the Mac with their hatred of Microsoft, much like Republicans attack Democrats when Democrats are in charge, only to find themselves on the defensive when the sides switch. Windows users, who had almost forgotten about the Mac, initially laughed at Mac users and their intense love for a plastic cube of electronics. But then, as Apple starting gaining market share and increasing respect for its design chops, they started to fight back.
Last year, Moltz created the “Artie MacStrawman” character as a symbol of those counterattacks on Mac users, as an allegory for the “strawman” theory of debate that intentionally exaggerates an opponent’s position to make it look more ridiculous. Many of those who criticize Mac users often come back to the whole “those crazy Apple cult people” thing, in that just because one Apple fan “mindlessly worships Steve Jobs” and “blindly buys anything Apple releases no matter how dumb and stupid and dumb it is,” they all do.
But let’s be honest: we’ve all seen that person in action in discussion forums on this site and many others. “Windows users aren’t put off by the ‘depth of passion’ that Mac users have. They are put off by the sheer futility of trying to make a rational argument with someone devoid of rational thought,” said Ken Webber, another News.com reader.
This “debate” has been polluting the Internet for more than a decade, but Apple is no longer a company to be laughed at. It’s selling more and more Macs to first-time Mac users. College campuses and hipster coffee shops are bastions of backlit Apple logos. Even businesses, long the last line of defense against the encroachment of the Mac, are changing their mind as programs like Boot Camp give Mac users a way to gain access to corporate applications developed for Windows. And as we start doing more and more work over the Internet, rather than on our desktop software, the compatibility issue becomes less and less relevant.
Yet the desire to be separate continues. Hank Stuever of The Washington Post bemoaned the trendy Apple user in a December 9 story about the Apple retail experience. “The demi-privacy of it, the clubby feeling–I know that you know that I know that we know and love Macs like nobody else does–is fading away.” Tuesday morning, I posted a short item to my blog asking for contributions for this story. I received about 50 e-mails in about 50 minutes before I had to plead for a halt. The basic question I sent to those who wrote in was, “Why are Mac users so passionate about Apple?”
The responses were similar. Mac users feel an affinity to both their machines and their fellow users that the rest of the world simply doesn’t share. For some, it’s the emphasis on design, both in hardware and software. For others, it’s the way Apple focuses on applications that make it easier for them to be creative. “It’s hard to put my own feelings into words on this, but that’s just it: I have feelings for my Apple computer. Not in the creepy obsessive way or anything, but I genuinely love my iBook,” said Ryan Spilken, a News.com reader.
Many see Apple’s devotion to quality as a symbol of a bygone era for American business, and believe they have to support that kind of thinking. At some point, according to several readers, American industry became so bottom-line obsessed that it gambled that people would probably buy their products anyway if, little by little, they stripped out the costs, which would lower prices but in a fashion that also guaranteed more profit. We’ve seen this happen time after time in the automobile, consumer electronics, and computer industries, just to name a few, and while it works in the short-term, it doesn’t end well.
But still others see the basic Mac vs. PC debate as the computer industry’s version of Ford vs. Chevrolet, or Bud vs. Miller, or Michigan vs. Ohio State: people like to identify with groups and subcultures, and they do all sorts of ridiculous things in arbitrary support of whichever group they’ve chosen. Computers are no longer a novelty. Style and usefulness count for so much more these days, since people have had a computer and know what they like and what they hate. And no company does style better than Apple.
Now that Apple has momentum on its side, does this finally mean we’re nearing a day when we can have a coherent discussion of the pros and cons of Apple’s approach to the computing world? Probably not. After all, the Mac community has all the momentum on its side, and is unlikely to lift its foot off the gas now that more people are starting to come around to its point of view. And Apple hasn’t stopped making Mac vs. PC ads.
But here’s a challenge: if Mac users care about quality and excellent design, and Windows users are adamant about openness and ubiquity, let’s apply those same standards to the discussion of the computer industry. There are going to be Macs, and there are going to be PCs. This religious argument is very 1995; it’s time to move on.
