Of course, programmers doing custom work quickly is the source of about half our problems (the Windows environment supplies the other half).
Absolutely dead right. Unfortunately, quick custom programming is often required, because airports have so many levels of bureaucracy interconnected by so many computer systems and databases and operating systems... fortunately, the computers communicate with each other a lot easier than the people. "By the way, we're changing this aspect of the protocol tomorrow..."
When I heard Air Canada is running all their systems on Windows, I immediately thought I should send out letters as a consultant to their CIO offering a Linux replacement for simple servers. Depending on what adapters and IO cards they're using, I believe I could switch their entire structure at least here in Toronto.
Heheh... first off, you might be underestimating the complexity of airport systems. But you haven't seen the Air Canada computers, have you? Remember that AC is essentially a Crown Corporation... neither efficiency or intelligence are prerequisites their employees, though I feel badly for the front-line customer service people who have nothing to do with the airline's problems.
In Terminal 2, on the Domestic Departures level and area, there is a little hallway and a door. That little door leads you into an antique computer museum where the power lights are still lit, and the curator seems to be Dr. Emmett L. Brown.
It would take you weeks to figure out the cabling in that room, let alone the undocumented production code and weird structures of databases.
There are plenty of Linux techies here in Toronto wandering about unemployed while the companies are investing in Microsoft.
Yeah. It's amazing where you'll find Windows. For the past few days, the local public education cable channel has had a Windows login prompt misdisplayed.
Airport FIDS (Flight Information Display Systems) tend to run Windows. I used to manage a system of a few thousand displays running a weird Continental Airlines and Infax proprietary protocol. There were two big reasons for using Windows, despite the suckage. One is that it's a hell of a lot easier to find programmers who can do custom work quickly in the Windows enviroment. The other is that Windows support for things like multi serial cards and stuff is a lot better; we often didn't have too much choice in the hardware we had to use (strange implementations of the old current loop, on 16 ports, for example... with only one supplier). Airports are very conservative, and with good reason. They really don't like change. Lots of serial cabling and repeaters where Ethernet would have done a great job.
Why, given the nature of the department and (one would hope) its awareness of the threats, would they use IIS while more stable and more secure alternatives are still available?
This is like a fire station which keeps the bin full of oily rags next to the Captain's personal collection of matchbooks from world-famous hotels.
Looking at that site and seeing the fragile infrastructure they're using, I can't help but feel proud to be a Canadian. Jesus wept.
Re:KVM Switch Loathing, IIS in Ironic Places
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actually the bulletins appear to be a WARNING to the general public. Just because a site is on IIS doesn't mean it immedatly crap. Unless you know for 100% that the server is NOT patched and resionably secure; none of us can make an option either way.
Having said that, I would imagine that the seismology agencies in Japan are in seismically correct buildings... Isn't that exactly the same? It's not like they control the threats to the infrastructure, all they can do is provide information to civilians and government agencies.
Isn't using IIS, while there are still more secure and reliable alternatives, exactly the same?
Back to the Japanese: what with the paper houses with the stone roofs on active fault lines? And you go out and buy a Honda, presumably trusting them to design your brakes? I don't get it.
You wouldn't be that guy from the redgreen show by any chance ?
Steve Smith? No. But we are on first name basis (no kidding!) and I wear lots of flannel. He once did something on the show which really reminded me of snowblower couch races with friends, and I can't remember if I told him about it or not...
(Snowblower couch racing? You scoop sofas, mattresses and box-springs from the garbage and store them in your backyard. You buy beer and sharpen the ice-cutters on your snowblower. Then you invite over some friends with their own snowblowers and see who can demolish the upholstered furniture the fastest. Truly a good reason to own a snowblower in a warm climate.)
KVM Switch Loathing, IIS in Ironic Places
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You've got to be kidding....
No.
I hope that it was someone elses negligence & not yours!
Yes. In fact, I did learn something: there's a very good reason that I hate KVM switches.
Solution (probably falling on deaf ears, but I shall try anyway):
Keyboard and monitor on all servers. Monitors should be LCD to save UPS batteries. This way, if the UPS shutdown sequence fails, it can be done manually. (A distressing number of these machines run Redmond's cancer, so having one central "shutdown console" is less practical.)
Serial shutdown outputs from UPS will be "broadcast" to all hosts connected to that UPS. Will require making a custom cable with a few MAX232 line-driver ICs and hang it off a machine's PS/2 port for power.
Backup generator is rated for 90kW and showed only about 10kW load running emergency lights around the building. Time to tap out that extra 80kW of capacity. Why this wasn't checked before is an absolute mystery to me.
Reorganize server interconnections. The network switch for the users' LAN wasn't on UPS (but neither are the users, so it didn't seem like a big deal). However, over the years, some stuff has come to rely on mapped drives... fortunately in this case, we're not so lucky to have hard-mounted NFS anywhere.:)
Have occasional practice power outages before long weekends. Who doesn't test their UPS by unplugging it from time to time? [grin]
I guess I'll stop complaining about the 50 l-users who ignored my emails on Jul.28 - Aug.1 warning them of the impending RPC vulnerability worm that would destroy their data.... (well, it didn't destory their data, but they did ignore my warnings & they did get the worm!)
Quick and Dirty LIVE UPS Recharging Ideas
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Apparently not around my neck of the woods... I had fun doing traceroutes as the power came back up and seeing how far I could get as more and more routers along the way were returning to service.
Yeah, same up here in Ottawa, Canada... I was awakened early on Friday morning to the sound of my servers POSTing; my power was back in under 12 hours. I was lucky.:) (Made sure to double-check that hdparm was set to spin down the drives, that and killing the A/C were my contributions to energy efficiency.)
Of course, I had to wait for MY neighbourhood's power to come back up as my UPS died about 4.5 hours into the blackout; my wife won't let me add the additional 300lbs of batteries required to last a full 24 hours.:( Still, I was up and running before connectivity in my area was restored.
I don't have a UPS (well, I do, I got one free, but it's broken and I haven't had time to troubleshoot it - anyone got schematics for an APC Back-UPS Pro 280?), so your mileage may vary. If the UPS runs off 12V batteries, you might be able to:
cobble a set of binding posts onto the side of its case, in parallel with the battery, and connect them to the battery in a running car. (Essentially, "jump-start" your UPS. Start the car first.)
Replace the 12V gel-cel battery with a good old-fashioned car battery. Even a weak used one should run it for a lot longer, but I haven't seen how charge current is regulated when the UPS is on AC, so I don't know how well the UPS's charging circuits will tolerate it.
Scoop an old gas lawnmower out of the garbage (Briggs and Stratton or Techumseh 4-stroke motors are preferable and very reliable if you keep them well tuned). Fix it, and install a pulley where the blades were (usually a 3/4" or 1" keyed shaft, and you want to take a 4L belt of the required length). Cut a hole in the deck, install a bracket, and hang a GM 1-wire alternator (1975-1985 models) in there. The lawnmower's deck is ground, the plastic-insulated bolt on the back is the positive. Mount a car battery onto it, and you have a portable jump-starter and 12V generator. Good also to weld on a perch for your toolbox. (Built one for myself, works *great* in junkyards when you want to test compression or oil pressure in an old car.)
Note that I don't know how the UPS's inverter will handle running at rated load for longer than the internal battery is capable, nor do I expect that the UPS will have much noise suppression on the battery leads - after all, batteries themselves are pretty much noise-free electrical sources and alternators are not.
Map of UPS battery exhaustions
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You don't have backup power on your home LAN? Pffft, and you call yourself a geek.
From what I know, this failure happened from New York City to Ohio in a matter of under a minute. So, I guess the dots are more representative of the average lifespan of the (formerly) fully-charged batteries in one's UPS.
As for me, I was dead in the water. At home, it was instantaneous (I'm too cheap to buy a UPS for a site which is just for my personal amusement); at work, it was 10 minutes of standing there in the server room listening to the frantic beep-beep-beep of UPSes all around me, and then rushing around to connect low-power LCD monitors to the servers that someone else forgot to connect to the UPS's shutdown signals... (of course, this after the realization that the emergency generator is running, but not actually even connected to the servers... [grumble])
...kely over time individual drivers each threw a small amount out their windows gradually growing into an eyesore, that affected everyone. Enviromental pollution is like that. A little here, and a little there, and then you all wonder why you're having all these health problems.
No. The absence of catalytic converters isn't like that. Catalytic converters replace two fairly benign pollutants with one not-so-benign pollutant, and decrease gas mileage which increases CO2 pollution.
And yes, I'm from a big city.
Am I the only one who sees how wacked the above is? You complain about "enviro-wacko" laws and how they're driving business away. And in the next complain about how companies freed from the shackles of "enviro-wacko" laws are abusing their environment. So which is it?
True. There is a contradiction there. But wouldn't you trust industry in a first-world country more than industry in a third-world country?
I think I answered this same rant somewere else. You speak of economy of scale, but ignore it when it comes to fuel cells. Currently the technology isn't up to the standards that we would ask of a common power plant. But mass production can do for fuel cells the same thing that it does for everything else. It can make it cheaper to make, and operate. Improve it's reliability as well. Note as well that we presently get along well with individual gas furnaces without majour headaches. Same with other majour appliances (and that's what a fuel cell will be). Also when we talk about using fuel cells, we're talking at least a 1:1 ratio, maybe greater for greater individual demands. Second your fuel for the multitudes is handled quite adequately already. A lot of people already get their fuel (be it LNG or fuel oil) via a truck. In other words a nonissue, and if you still want to argue, there's in most homes a natural gas line.
The difference being is that it's a hell of a lot more inefficient to ship heat than it is to ship electricity. That's why we have individual furnaces. Perhaps you missed that lecture in first year Engineering Thermodynamics?
As for fuel cells, yeah, they might be great someday. But a real-world situation besides mass-production which you apparently don't understand is that fuel cells are extremely vulnerable to contaminated fuel. The sort of things which collect in tanks and are sufficiently fine to go right through fuel filters destroy fuel cells and destroy their osmotic membranes.
What a foolish thing to say. Incandescents can be made in a "chinease sweatshop" as any other bulb (not that you have any proof they were made in a sweatshop, but hey every rant needs a stereotype)).
Apparently, you don't understand how fluourescent lights work.
Incandescents are made of glass, steel and tungsten. Fluorescents require an electronic ballast (lots of nasty chemicals to make electronics), fluorescent materials (the white powder that comes out of broken fluorescent tubes) and mercury. That's what goes into them at the Chinese sweatshops. I don't care where they're made, frankly. Fluorescent lights are basically hazardous waste. But you already knew that, didn't you?
Yes, lets do. How many houses catch fire from their furnaces? How many catch fire from the dryer? Face it the world isn't a safe place, and using FUD isn't going to make it any safer.
How many furnaces are powered by internal combustion engines? Since fuel cells aren't practical yet - and getting their DC power onto the grid or used in the house is a Non-Trivial Issue - these things are going to have to be powered by internal combustion engines, meaning all the inherent inefficiencies. And meaning having something a little more sophisticated than a furnace oil burner running. More sophisticated means more complicated with more points of failure.
Comparing a generator with a furnace is idiocy at its finest.
Please remember that when the subject of landfill overflowing comes up, and they are building it's replacement next
Take the most common electrical generator most of us own, the alternator in your car. This item is driven by the engine's crankshaft, and it's speed goes uo as the crankshaft's revolutions speed up. Of course too fast, and the power the alternator makes will cook the battery (which it feeds). Hence the built in voltage regulator that all alternators have.
Very good.
Is the answer so obvious that they have missed it?
Okay. Electrical power is distributed as AC (alternating current). Here, it's 60 cycles. That means that the sinewave goes through 360 degrees every 1/60th of a second.
Now, consider putting *two* generating systems together in parallel. The two sinewaves have to match up *perfectly* in terms of both phase (in degrees) and voltage, otherwise you end up with interference between the two and a massive inefficiency. The energy lost to this inefficiency ends up as heat somewhere in the system, and blows stuff.
For these sinewaves to match in phase, they must also inherently match in frequency.
Generators (alternators, really; alternators produce AC, it's just that the one in your car includes rectifier diodes) work by turning coils of wire in a magnetic field, and the sinewave is a consequence of that. Therefore, the frequency is a function of the rotational speed of that loop of wire - the faster you turn the generator, the higher your frequency.
Here's the big problem: It's pretty hard to control the rotational speed of natural sources to the sort of precision required. This is why simple AC voltage regulators won't work - the phase is critical, not just the voltage.
So the best solution is to generate a sinewave through a big-assed version of the inverter which converts DC battery power to AC in your UPS. Of course, to get big iron which produces a good enough sinewave to go onto the grid without problems is a Non-Trivial Task.
Hence the problem.
Of course, you could use a dynamotor. ("dynamotor" = motor driving a dynamo (generator)). A precise DC motor could drive an alternator and do it - but they disappeared around about the time that car radios stopped having vibrators (nothing sexual, type "car radio vibrator" into Google) for the very same reasons of inefficiency.
Keep in mind that you're taking a DC voltage and trying to convert it to AC. AC, being varying, means that the DC source must be made to vary. Previous solutions have universally been resistive. If you take 120V from your wall socket, rectify it with a diode and filter it with a capacitor, your meter will show you 170V. That's the *peak* voltage of the sinewave, but the Root Mean Square (RMS) value is 120V. ( sqrt(2)*120 ). Conversely, if to go from DC to AC, 170/sqrt(2). In simplest terms, if you're trying to power a load, therefore, you require sqrt(2)*$DESIRED_AC_POWER going in. And that assumes 100% efficiency when the inverter is in full on state at the peaks. All that energy is wasted as heat while the inverter's semiconductors are in their linear states.
Bullshit, we can blame ourselves for overconsumption and the NIMBY's (Not In My BackYard) more than the environmentalists. I hate that knee-jerk response to everything - "It's the environmentalists fault".
So often it is. Look at catalytic converters on cars if you don't believe me - they eat about 20% of your gas mileage by making the engine pump exhaust out against a restriction. Acid rain wasn't caused by cars until the tree-huggers pestered the EPA and got them on all cars. Before we had a little unburnt gasoline and a little NOx leaving tailpipes. Both are unpleasant, but nature copes with them because they're both inherently unstable in the atmosphere. Now, we have 20% more CO2 than is necessary from each vehicle, and the added bonus of sulphur hydroxide formed in the catalytic!
Or consider all the enviro-wacko laws on industry. Fine. Between enviromentalists and trade unions pushing up the cost of doing business, I don't blame them for moving to third-world hell-holes. And that's better? Love Canal is happening in China, and protesters demanding reasonable safety from industrial waste aren't being quietly placated, but they're being shot. Not only that, but now we have to waste energy shipping raw materials and finished product greater distances!
Environmentalism is too often about stupid band-aid solutions and silly platitudes espoused by people with arts degrees and toe rings. Real environmental solutions are about doing unpleasant things. Forget the crappy low-flow toilet that makes dimwits feel oh-so-good but takes 6 flushes to get rid of the Dark Matter. Use a regular toilet which takes 1 flush. Better still if you can, use the waste water from your washing machine or shower to flush it.
Even with all the technology that we've created to make lower power devices we just find a way to get more devices. I saw how they were working on LED's as a better, more efficient lightsource that can do task lighting for about 1 watt of power. I mention this at work and some jackass comes up behind me and says how cool it would be to be able to have a wall full of them and be able to change the color of his walls with his mood - POWER SAVINGS - what power savings?
Well, assuming he wants a comfortable quantity of light in his room, then he will only be able to stand to use so much power in his LEDs, right? If the guy wants to supplant his ordinary room lighting with this, isn't that fine, or do we no longer have a society based on personal freedom? The net energy consumption would be less than ordinary room lighting... woah, wait a minute. Have we considered the energy and environmental cost involved in processing all those little silion wafers being made into LEDs? When you consider the energy going into the whole system, incandescents aren't so bad.
It's a balancing act. First we have a grid that's just too old and extremely expensive to update. There's a mix of powerplants that are aging, there's poor planning, no incentive to change energy usage habbits, poor city design that promotes heat which in turn increases energy consumption due to airconditioners, extra showers, fans, and refridgerators. Then you have people who don't want a soot belching powerplant in their backyard, or off their favorite camping spot, nor do they want to pay extra for a more expensive cleaner burning plant, or pay extra tax dollars to have research into alternative plans like more efficient solar/wind/water/et al.
I agree with everything you've said there.
My feeling is that we need a decentralized system where power is created in much smaller "nodes" and distributed from those points. Nodes could be created in house basements or in larger buildings and be connected to more evenly distribute power over shorter distances reducing the waste that happens when power has to be transmitted over miles and miles of cable to a destination.
No. Not a good idea.
Power plants operate on a couple of principles, one of them being economy of scale. This economy of scale suggests,
WTF are "power electronics"? Couldn't you at elast have given us some tiny hint, so that upon clicking your links we'd be going into the articles having some vague clue how to parse your summary?
Power is (work / time). When used to describe electronics, it generally means (large work / time). In other words, over any arbitrary scale, big.
Electronics is widely described as the science of the control of electrons. The term first originated with the 1904 Flemming diode, the first electron-controlling device. The DeForrest Audion and other early triodes were also early electron-controlling devices. Systems which used electron-controlling devices were generally called "electronic".
Power electronics, therefore, suggests devices which control arbitrarily large quantities of electrons.
While power electronics are often held to be small stuff like regulators in a computer power supply or MOSFETs in a car stereo amplifier or even the IGBTs which turn on and off windings in elevator motors, real power electronics are generally bigger stuff than Radio Shack sells. Hockey-puck shaped SCRs which require water cooling when they're installed to control aluminum smelters. Or the stuff the power company uses. (Note that word again...)
In other words, stuff which can be compared to a 2N3055 in exactly the same way as you'd compare your Palm to a Cray.
I don't know if I agree with that or not. I do happen to remember my father adding aluminum foil, coat hangers, and various other sundries to our standard set top pair or rabbit ears to increase the reception. it wasn't rocket science. it wasn't science it all. it was trial and error.
Use a quality antenna... VHF TV channels 2-6 and 7-13 are in different parts of the spectrum; you cannot handle them efficiently with the same antenna... to say nothing of UHF. If it's a rod antenna (my favorites are 1/2 wave), make sure it's isolated from, but on, a good ground plane. Old BBQ grills work well for this at high frequencies, but remember that you want each side of your ground plane to be twice the length of the antenna - ie, one wavelength. Place the antenna up high. Make sure you polarize it the same way as the transmitter - AM/FM radio is usually vertically polarized, TV and SW radio are horizontal. Move the antenna away from all conductive objects (including drywall screws embedded in the walls). Replace 300 ohm twin-lead with 75 ohm coax by using a matching transformer right at the driven elements on the antenna. Beware of reflected radio waves coming off everything from wet trees to building walls. Orient the antenna to receive the strongest signal, whether it's the main signal or a reflection off a permanent object. Any other technique (ie. aluminum foil to unbalance the dipole) is a poor I-don't-care-if-I-lose-12dB-of-good-signal response to the problem. It may work in local areas with strong signals, but it's neither reliable nor efficient.
Among cheap antennas... UHF loops are great, if you use a UHF-capable matching tranformer to drive coax, and mount the loop far away from all conductive objects. Rabbit ears are junk and are really only good for strong reception areas, unless you place the ears horizontally at 180 degrees to each other, place it on a NON-conductive surface, and retract the telescopic elements to the right length for the frequency of the station you're trying to receive.
In short, if you know what you're doing, you'll avoid the aluminum foil and random chunks of coathanger. Math is your friend, and it will blow trial-and-error out of the water every time.
The standard Microsoft weenie excuse for instability in the past has been "it's the drivers!", blaming the video drivers is a favourite.
Unless it's an ATI product, in which case you can be 100% assured that it *is* the video drivers.
In my experience, you can bring any Windows 2000 or XP machine with any model of All in Wonder to a screeching blue HALT by simply doing such outlandish and unreasonable things as
Changing the channel
Changing the size of the video window
Allowing a hover-over or dropdown menu to overlap with the video window
Letting DPMS turn off your monitor
Attempting to bring your computer back from standby
Attempting to record or save recorded video using ATI's own AVI or MPEG recording software, regardless of codec used
And for those who really like fun, try an ATI All In Wonder Pro on Windows 2000. A couple of years ago, I deployed a couple of hundred of them at a Toronto TV station. A year later, they asked me to upgrade all their systems to Windows 2000. Constant random lockups of the whole system, requiring not just a reboot but a power cycle. Needless to say, they were not very pleased - you spend $300 on a video card, and you kind of expect that they'll provide drivers for at least a couple of years. ("They've been around forever. Besides, they're a good hometown company! Their headquarters are just 5 minutes from here, up the 404 in Markham."). Their news department almost did a story on crappy software but it was vetoed because news is supposed to be impartial.
As for ATI, I will never buy another ATI product ever again, for myself or for anyone else.
Yeah, so the deal is this site is essentially as it was back in 1993. I am recreating the whole site as we speak.
Keep a copy somewhere for an online museum!
Sorry... usually a site like that is designed by teenage girls using Geocities accounts to post tributes to their favorite teen idol. Flaming them for their animated GIFs, horrible background, and MIDI assaults when I accidentally happen onto their pages is, of course, pointless. I guess I had a lot of built-up tension. Sorry.
Ever heard the Growing Pains theme in MIDI? Urk. B.J. Thomas and Jennifer Warnes must not be impressed.
Even my little old G3 iMac is capable of handling quite a load from Slashdot and this site is serving up graphics intensive stuff.
I suspect, given the subject matter of your site, the chosen backgrounds and text colors are designed to test a theory that extreme garishness may cause blindness?
...but I posted links to three images, around 80KB each, on my home server a few days ago fairly deep down in the discussion and got 3904 hits from it. It didn't kill my server (Pentium 133MHz, 64MB RAM, Debian 3.0, Apache 1.3.26, 3000/256 cable) and didn't result in any nasty letters from my ISP.
Yeah, I've been hammered a few times with exactly the same effect. (Pentium 90, 48 megs RAM, simple dynamic content, Apache, Linux.) I believe the primary limitation in my case is the speed of my DSL (1200kbps/128kbps less PPPoE overheads); when I've been Slashdotted, I've checked my outbound traffic with iptraf and found that I'd maxed out my upload speed and page requests were occasionally timing out rather than melting down the server. (Though seeing literally nothing but CGI scripts and httpd daemons on top's display is exhilarating, almost as good as skydiving but not quite as good as a big-block V8 or sex.)
I'm sorry, but fox29 buffalo is crap, even when you don't need a huge antenna to get it.
Well, this is true. But I like the Sunday night line-up.
Up here in Canada, there's a CRTC (Canadian equivalent to FCC) rule that if an American channel and a Canadian channel are carrying the same show, the cable company has to switch and carry the Canadian station over the American one. Presumably to benefit Canadian broadcasters and advertisers.
Problem is that the Canadian stations are showing the same three episodes over and over, or without stereo sound, etc. They frequently forget to make the switch until about 10 minutes in, so you get to watch the opening of a new episode then miss out to a very tired re-run. The Simpsons became intolerable after the Apu-has-babies episode was run three times in three months while new episodes were on.
Just more protectionist bullcrap making me yearn for a Green Card.
I'm sure their success is attributed more to knowing what you are doing in a McGyver'ish way than simply hacking.
Yeah, antennas don't respond well to guesswork.
Most people don't know that an antenna rings electrically the way a tuning fork rings mechanically. There's only a very limited frequency range that an antenna will handle well.
On top of that, as the frequency increases, radio waves behave more and more like light. And problems like stray capacitance and stray inductance - tiny values in farads and henries - become very important design considerations as the frequency increases.
But a well-designed amateur antenna can be very capable. The radio waves don't care if you make the elements out of silver encrusted canine feces, if they're the right lengths.
UHF TV band, around 450MHz. Design is extremely critical here. But by doing a little math first, I designed and built a 12-element Yagi (looks like an ordinary rooftop TV antenna but with more elements) which is tuned to channel 29. It's very directional, meaning I have to be pointed within a few degrees of the transmitter. But I can also watch WUTV Fox 29 from Buffalo, in Ottawa Canada, without shelling out for cable. Cost? Scrap of wood, old coat hanger wire trimmed to within 1/16" of the design dimensions, plastic tubing and clips to hold the elements to the board, old 75-300 ohm matching transformer gutted for its balun and soldered directly to the driven elements and feeding coax. Essentially free. Not waterproof, so it lives in my attic.
Those are probably bogus emails to harvest valid emails to sell. Usually they put a 1x1px image in the mail so they know who read it and who did not, then they sell those addresses as "1million valid addresses, only $99.99!!!"
Now, I'm gonna sound like a luddite, but there's a good reason. I *hate* HTML e-mail.
Having said that, there are times when I'd like to be able to embed an image to be grabbed from a remote server so that I can determine when a user is online.
I've never looked into creating HTML e-mail more than idly playing with the settings in Eudora (yeah, I run Windows 2000 on my primary workstation, Linux and the BSDs on the others). It seems that Eudora 5.2 won't allow it, unless I'm missing something.
How. I understand the area under a graph is the intergral of the formula of the graph, but if you have an everyday shape, chances are its not created by a known mathematical formula. how do you work out the area using calculus?
Ahh... Now we discover the joy of Infinite Series. Infinite series allows you to do all sorts of things to (arbitrary) precision. (Arbitrary in that it won't spit back an answer to 300 decimal places unless you make the program you write run through the loop 300 times...)
Basically, here's the idea. You can do a regression of the known points on the graph to come up with a function (formula) to describe the relationship. Regressions come from infinite series, but are used in a plug-and-play format in statistics courses. Also annoyingly, Excel 95 and up includes the capability to do them in the Data Analysis tools, OpenOffice does not yet [grumble grumble]. Anyway, once you have a function, you simply integrate it to find the area.
My favorite part of all this is that the series usually gives you a nice long sum of little polynomial expressions, which are individually and collectively easy to integrate.
Practical applications? Fourier Transforms and Fast Fourier Transforms. They allow you to express any function (audio waveform?) as a sum of different overlapping sinewaves. From there, you can do all the math you want on them. MP3 and Ogg codecs do this.
The best piece of advice I can give anyone trying to learn from a textbook is to tell them to work through the problems. Anyone should be able to pick up many of the textbooks listed below and work though as many of the problems as time allows (limited either by patience or by real life events). Most textbooks provide answers to selected problems, so you can check your progress.
Absolutely, 100%. Nobody is born with the ability to take a triple scalar product or multiply two matrices (both happening in your video card when you're playing Doom!). As a great Calculus teacher once announced to his class through a thick French Canadian accent, "Math is not a spectator sport." (Actually, it came out as "Matt ees not a spectator sport.")
Having said that, Calculus is my favorite kind of math. It's incredibly elegant and probably the most useful advanced math, as it touches everything you do. Consider your car. If you calculate your speed using a watch and the odometer, you have an idea how fast you were going, but your speedometer is actually showing you the value of the derivative at any instantaneous time. Your speedometer shows the rate of change of position (distance travelled) at any instantaneous time. That's calculus.
Don't be afraid. "Calculus" (besides being a formal term for tartar the dentist scrapes off your teeth) means small stones in Latin... small stones as used for counting.
Two *great* books on the subject:
Sylvanus P. Thompson's 1910 classic Calculus Made Easy is still in print and remains as relevent as ever. It's funny ("To Deliver you from the Preliminary Terrors" is the title of the first chapter) and it's full of interesting tidbits. (Do you know where the time units of minutes and seconds got their names?) Hit Amazon.com or Bibliofind to get a copy.
Applied Calculus - an Intuitive Approach is great, too. Faber, Freedman and Kaplan. Starts with First Principles and takes you to fairly advanced integration in an easy-to-read format.
Remember: Do the problems, succeed. Don't do the problems, fail. It's that simple.
Oh yeah... Don't power it off PS2 ports.
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The last thing, too.. Don't power anything like this (the pad or the fan) off a PS2 port. I think that most of them are fused for about 20-50mA at 5V. You'd be better off finding a mouse with a pair of extra wires and making a little adapter at the computer end to drop 5V or 12V from the power supply into the mouse. It might be a good idea to consider adding an inline fuse there, too. (If the dog eats the mouse, you don't want to lose your uptime record when the power supply cuts out.)
Re:Now if only...
on
Clammy Modding
·
· Score: 3, Interesting
Now if only...
...he'd hooked the BreezePad up to the exhaust of a vacuum cleaner rather than a wimpy little computer fan.
HoverMouse, anyone?
I should try mousing on the air hockey table to see how slippery it is....
Seriously, too. To cut acrylic (or most other plastics) neatly, use masking tape along the line you're cutting (helps avoid chips). Don't use metalworking tools if you can avoid it, the teeth are too fine and get clogged. Saw *slowly* because the friction will melt the plastic. Pouring water (ie. from a garden hose) as you cut is good to wash away chips and keep the piece cool. Leave the paper backing on the plastic until you're done *all* the cutting and drilling. Deburr the holes by using a countersinking bit BY HAND for a couple of turns. And finally, always remember: measure once, cut twice! [grin]
If you need this to work with an optical mouse, make sure any LEDs in the pad are a very different color. Mine, for example, has a red LED and I'd imagine that its sensor is designed for that, so blue LEDs would probably upset it very little... but I haven't tested it.
Once you've got the cutting and drilling done, you could take off the paper backing and take the piece to a sandblasting shop and have them blast it gently with walnut shells or other soft blasting media. That should frost it nicely so that it works with an optical mouse, and the whole thing would glow, too.
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Of course MIT is the best engineering school - they have the best understanding of engineers!
MIT Traditonal, The Engineer's Drinking Song, as sung by engineers worldwide.
Search for it on Kazaa, you'll find the Chorallaries excellent version.
Of course, programmers doing custom work quickly is the source of about half our problems (the Windows environment supplies the other half).
Absolutely dead right. Unfortunately, quick custom programming is often required, because airports have so many levels of bureaucracy interconnected by so many computer systems and databases and operating systems... fortunately, the computers communicate with each other a lot easier than the people. "By the way, we're changing this aspect of the protocol tomorrow..."
When I heard Air Canada is running all their systems on Windows, I immediately thought I should send out letters as a consultant to their CIO offering a Linux replacement for simple servers. Depending on what adapters and IO cards they're using, I believe I could switch their entire structure at least here in Toronto.
Heheh... first off, you might be underestimating the complexity of airport systems. But you haven't seen the Air Canada computers, have you? Remember that AC is essentially a Crown Corporation... neither efficiency or intelligence are prerequisites their employees, though I feel badly for the front-line customer service people who have nothing to do with the airline's problems.
In Terminal 2, on the Domestic Departures level and area, there is a little hallway and a door. That little door leads you into an antique computer museum where the power lights are still lit, and the curator seems to be Dr. Emmett L. Brown.
It would take you weeks to figure out the cabling in that room, let alone the undocumented production code and weird structures of databases.
There are plenty of Linux techies here in Toronto wandering about unemployed while the companies are investing in Microsoft.I know. It's horrible.
Yeah. It's amazing where you'll find Windows. For the past few days, the local public education cable channel has had a Windows login prompt misdisplayed.
Airport FIDS (Flight Information Display Systems) tend to run Windows. I used to manage a system of a few thousand displays running a weird Continental Airlines and Infax proprietary protocol. There were two big reasons for using Windows, despite the suckage. One is that it's a hell of a lot easier to find programmers who can do custom work quickly in the Windows enviroment. The other is that Windows support for things like multi serial cards and stuff is a lot better; we often didn't have too much choice in the hardware we had to use (strange implementations of the old current loop, on 16 ports, for example... with only one supplier). Airports are very conservative, and with good reason. They really don't like change. Lots of serial cabling and repeaters where Ethernet would have done a great job.
How about this one: The Canadian government's Office Of Critical Infrastructure Protection and Emergency Preparedness runs IIS.
Why, given the nature of the department and (one would hope) its awareness of the threats, would they use IIS while more stable and more secure alternatives are still available?
This is like a fire station which keeps the bin full of oily rags next to the Captain's personal collection of matchbooks from world-famous hotels.
Looking at that site and seeing the fragile infrastructure they're using, I can't help but feel proud to be a Canadian. Jesus wept.
actually the bulletins appear to be a WARNING to the general public. Just because a site is on IIS doesn't mean it immedatly crap. Unless you know for 100% that the server is NOT patched and resionably secure; none of us can make an option either way.
Having said that, I would imagine that the seismology agencies in Japan are in seismically correct buildings... Isn't that exactly the same? It's not like they control the threats to the infrastructure, all they can do is provide information to civilians and government agencies.
Isn't using IIS, while there are still more secure and reliable alternatives, exactly the same?
Back to the Japanese: what with the paper houses with the stone roofs on active fault lines? And you go out and buy a Honda, presumably trusting them to design your brakes? I don't get it.
You wouldn't be that guy from the redgreen show by any chance ?
Steve Smith? No. But we are on first name basis (no kidding!) and I wear lots of flannel. He once did something on the show which really reminded me of snowblower couch races with friends, and I can't remember if I told him about it or not...
(Snowblower couch racing? You scoop sofas, mattresses and box-springs from the garbage and store them in your backyard. You buy beer and sharpen the ice-cutters on your snowblower. Then you invite over some friends with their own snowblowers and see who can demolish the upholstered furniture the fastest. Truly a good reason to own a snowblower in a warm climate.)
You've got to be kidding....
No.
I hope that it was someone elses negligence & not yours!Yes. In fact, I did learn something: there's a very good reason that I hate KVM switches.
Solution (probably falling on deaf ears, but I shall try anyway):
- Keyboard and monitor on all servers. Monitors should be LCD to save UPS batteries. This way, if the UPS shutdown sequence fails, it can be done manually. (A distressing number of these machines run Redmond's cancer, so having one central "shutdown console" is less practical.)
- Serial shutdown outputs from UPS will be "broadcast" to all hosts connected to that UPS. Will require making a custom cable with a few MAX232 line-driver ICs and hang it off a machine's PS/2 port for power.
- Backup generator is rated for 90kW and showed only about 10kW load running emergency lights around the building. Time to tap out that extra 80kW of capacity. Why this wasn't checked before is an absolute mystery to me.
- Reorganize server interconnections. The network switch for the users' LAN wasn't on UPS (but neither are the users, so it didn't seem like a big deal). However, over the years, some stuff has come to rely on mapped drives... fortunately in this case, we're not so lucky to have hard-mounted NFS anywhere.
:)
- Have occasional practice power outages before long weekends. Who doesn't test their UPS by unplugging it from time to time? [grin]
I guess I'll stop complaining about the 50 l-users who ignored my emails on Jul.28 - Aug.1 warning them of the impending RPC vulnerability worm that would destroy their data.... (well, it didn't destory their data, but they did ignore my warnings & they did get the worm!)Heheh... Yeah, I know the type.
Along those lines, how's this for bitter irony? The Canadian government's "Office of Critical Infrastructure Protection and Emergency Preparedness" runs IIS on Windows 2000. (Note also the subjects of a couple of the bulletins on their site...) Somehow, this reminds me of doctors who smoke, or mechanics who don't change their oil.
My tax dollars at work. [sigh]
Apparently not around my neck of the woods... I had fun doing traceroutes as the power came back up and seeing how far I could get as more and more routers along the way were returning to service.
Yeah, same up here in Ottawa, Canada... I was awakened early on Friday morning to the sound of my servers POSTing; my power was back in under 12 hours. I was lucky. :) (Made sure to double-check that hdparm was set to spin down the drives, that and killing the A/C were my contributions to energy efficiency.)
Of course, I had to wait for MY neighbourhood's power to come back up as my UPS died about 4.5 hours into the blackout; my wife won't let me add the additional 300lbs of batteries required to last a full 24 hours.I don't have a UPS (well, I do, I got one free, but it's broken and I haven't had time to troubleshoot it - anyone got schematics for an APC Back-UPS Pro 280?), so your mileage may vary. If the UPS runs off 12V batteries, you might be able to:
Note that I don't know how the UPS's inverter will handle running at rated load for longer than the internal battery is capable, nor do I expect that the UPS will have much noise suppression on the battery leads - after all, batteries themselves are pretty much noise-free electrical sources and alternators are not.
You don't have backup power on your home LAN? Pffft, and you call yourself a geek.
From what I know, this failure happened from New York City to Ohio in a matter of under a minute. So, I guess the dots are more representative of the average lifespan of the (formerly) fully-charged batteries in one's UPS.
As for me, I was dead in the water. At home, it was instantaneous (I'm too cheap to buy a UPS for a site which is just for my personal amusement); at work, it was 10 minutes of standing there in the server room listening to the frantic beep-beep-beep of UPSes all around me, and then rushing around to connect low-power LCD monitors to the servers that someone else forgot to connect to the UPS's shutdown signals... (of course, this after the realization that the emergency generator is running, but not actually even connected to the servers... [grumble])
No. The absence of catalytic converters isn't like that. Catalytic converters replace two fairly benign pollutants with one not-so-benign pollutant, and decrease gas mileage which increases CO2 pollution.
And yes, I'm from a big city.
Am I the only one who sees how wacked the above is? You complain about "enviro-wacko" laws and how they're driving business away. And in the next complain about how companies freed from the shackles of "enviro-wacko" laws are abusing their environment. So which is it?
True. There is a contradiction there. But wouldn't you trust industry in a first-world country more than industry in a third-world country?
I think I answered this same rant somewere else. You speak of economy of scale, but ignore it when it comes to fuel cells. Currently the technology isn't up to the standards that we would ask of a common power plant. But mass production can do for fuel cells the same thing that it does for everything else. It can make it cheaper to make, and operate. Improve it's reliability as well. Note as well that we presently get along well with individual gas furnaces without majour headaches. Same with other majour appliances (and that's what a fuel cell will be). Also when we talk about using fuel cells, we're talking at least a 1:1 ratio, maybe greater for greater individual demands. Second your fuel for the multitudes is handled quite adequately already. A lot of people already get their fuel (be it LNG or fuel oil) via a truck. In other words a nonissue, and if you still want to argue, there's in most homes a natural gas line.
The difference being is that it's a hell of a lot more inefficient to ship heat than it is to ship electricity. That's why we have individual furnaces. Perhaps you missed that lecture in first year Engineering Thermodynamics?
As for fuel cells, yeah, they might be great someday. But a real-world situation besides mass-production which you apparently don't understand is that fuel cells are extremely vulnerable to contaminated fuel. The sort of things which collect in tanks and are sufficiently fine to go right through fuel filters destroy fuel cells and destroy their osmotic membranes.
What a foolish thing to say. Incandescents can be made in a "chinease sweatshop" as any other bulb (not that you have any proof they were made in a sweatshop, but hey every rant needs a stereotype)).
Apparently, you don't understand how fluourescent lights work.
Incandescents are made of glass, steel and tungsten. Fluorescents require an electronic ballast (lots of nasty chemicals to make electronics), fluorescent materials (the white powder that comes out of broken fluorescent tubes) and mercury. That's what goes into them at the Chinese sweatshops. I don't care where they're made, frankly. Fluorescent lights are basically hazardous waste. But you already knew that, didn't you?
Yes, lets do. How many houses catch fire from their furnaces? How many catch fire from the dryer? Face it the world isn't a safe place, and using FUD isn't going to make it any safer.
How many furnaces are powered by internal combustion engines? Since fuel cells aren't practical yet - and getting their DC power onto the grid or used in the house is a Non-Trivial Issue - these things are going to have to be powered by internal combustion engines, meaning all the inherent inefficiencies. And meaning having something a little more sophisticated than a furnace oil burner running. More sophisticated means more complicated with more points of failure.
Comparing a generator with a furnace is idiocy at its finest.
Please remember that when the subject of landfill overflowing comes up, and they are building it's replacement next
Take the most common electrical generator most of us own, the alternator in your car. This item is driven by the engine's crankshaft, and it's speed goes uo as the crankshaft's revolutions speed up. Of course too fast, and the power the alternator makes will cook the battery (which it feeds). Hence the built in voltage regulator that all alternators have.
Very good.
Is the answer so obvious that they have missed it?Okay. Electrical power is distributed as AC (alternating current). Here, it's 60 cycles. That means that the sinewave goes through 360 degrees every 1/60th of a second.
Now, consider putting *two* generating systems together in parallel. The two sinewaves have to match up *perfectly* in terms of both phase (in degrees) and voltage, otherwise you end up with interference between the two and a massive inefficiency. The energy lost to this inefficiency ends up as heat somewhere in the system, and blows stuff.
For these sinewaves to match in phase, they must also inherently match in frequency.
Generators (alternators, really; alternators produce AC, it's just that the one in your car includes rectifier diodes) work by turning coils of wire in a magnetic field, and the sinewave is a consequence of that. Therefore, the frequency is a function of the rotational speed of that loop of wire - the faster you turn the generator, the higher your frequency.
Here's the big problem: It's pretty hard to control the rotational speed of natural sources to the sort of precision required. This is why simple AC voltage regulators won't work - the phase is critical, not just the voltage.
So the best solution is to generate a sinewave through a big-assed version of the inverter which converts DC battery power to AC in your UPS. Of course, to get big iron which produces a good enough sinewave to go onto the grid without problems is a Non-Trivial Task.
Hence the problem.
Of course, you could use a dynamotor. ("dynamotor" = motor driving a dynamo (generator)). A precise DC motor could drive an alternator and do it - but they disappeared around about the time that car radios stopped having vibrators (nothing sexual, type "car radio vibrator" into Google) for the very same reasons of inefficiency.
Keep in mind that you're taking a DC voltage and trying to convert it to AC. AC, being varying, means that the DC source must be made to vary. Previous solutions have universally been resistive. If you take 120V from your wall socket, rectify it with a diode and filter it with a capacitor, your meter will show you 170V. That's the *peak* voltage of the sinewave, but the Root Mean Square (RMS) value is 120V. ( sqrt(2)*120 ). Conversely, if to go from DC to AC, 170/sqrt(2). In simplest terms, if you're trying to power a load, therefore, you require sqrt(2)*$DESIRED_AC_POWER going in. And that assumes 100% efficiency when the inverter is in full on state at the peaks. All that energy is wasted as heat while the inverter's semiconductors are in their linear states.
That's why this is a big deal.
Bullshit, we can blame ourselves for overconsumption and the NIMBY's (Not In My BackYard) more than the environmentalists. I hate that knee-jerk response to everything - "It's the environmentalists fault".
So often it is. Look at catalytic converters on cars if you don't believe me - they eat about 20% of your gas mileage by making the engine pump exhaust out against a restriction. Acid rain wasn't caused by cars until the tree-huggers pestered the EPA and got them on all cars. Before we had a little unburnt gasoline and a little NOx leaving tailpipes. Both are unpleasant, but nature copes with them because they're both inherently unstable in the atmosphere. Now, we have 20% more CO2 than is necessary from each vehicle, and the added bonus of sulphur hydroxide formed in the catalytic!
Or consider all the enviro-wacko laws on industry. Fine. Between enviromentalists and trade unions pushing up the cost of doing business, I don't blame them for moving to third-world hell-holes. And that's better? Love Canal is happening in China, and protesters demanding reasonable safety from industrial waste aren't being quietly placated, but they're being shot. Not only that, but now we have to waste energy shipping raw materials and finished product greater distances!
Environmentalism is too often about stupid band-aid solutions and silly platitudes espoused by people with arts degrees and toe rings. Real environmental solutions are about doing unpleasant things. Forget the crappy low-flow toilet that makes dimwits feel oh-so-good but takes 6 flushes to get rid of the Dark Matter. Use a regular toilet which takes 1 flush. Better still if you can, use the waste water from your washing machine or shower to flush it.
Even with all the technology that we've created to make lower power devices we just find a way to get more devices. I saw how they were working on LED's as a better, more efficient lightsource that can do task lighting for about 1 watt of power. I mention this at work and some jackass comes up behind me and says how cool it would be to be able to have a wall full of them and be able to change the color of his walls with his mood - POWER SAVINGS - what power savings?
Well, assuming he wants a comfortable quantity of light in his room, then he will only be able to stand to use so much power in his LEDs, right? If the guy wants to supplant his ordinary room lighting with this, isn't that fine, or do we no longer have a society based on personal freedom? The net energy consumption would be less than ordinary room lighting... woah, wait a minute. Have we considered the energy and environmental cost involved in processing all those little silion wafers being made into LEDs? When you consider the energy going into the whole system, incandescents aren't so bad.
It's a balancing act. First we have a grid that's just too old and extremely expensive to update. There's a mix of powerplants that are aging, there's poor planning, no incentive to change energy usage habbits, poor city design that promotes heat which in turn increases energy consumption due to airconditioners, extra showers, fans, and refridgerators. Then you have people who don't want a soot belching powerplant in their backyard, or off their favorite camping spot, nor do they want to pay extra for a more expensive cleaner burning plant, or pay extra tax dollars to have research into alternative plans like more efficient solar/wind/water/et al.
I agree with everything you've said there.
My feeling is that we need a decentralized system where power is created in much smaller "nodes" and distributed from those points. Nodes could be created in house basements or in larger buildings and be connected to more evenly distribute power over shorter distances reducing the waste that happens when power has to be transmitted over miles and miles of cable to a destination.
No. Not a good idea.
Power plants operate on a couple of principles, one of them being economy of scale. This economy of scale suggests,
WTF are "power electronics"? Couldn't you at elast have given us some tiny hint, so that upon clicking your links we'd be going into the articles having some vague clue how to parse your summary?
Power is (work / time). When used to describe electronics, it generally means (large work / time). In other words, over any arbitrary scale, big.
Electronics is widely described as the science of the control of electrons. The term first originated with the 1904 Flemming diode, the first electron-controlling device. The DeForrest Audion and other early triodes were also early electron-controlling devices. Systems which used electron-controlling devices were generally called "electronic".
Power electronics, therefore, suggests devices which control arbitrarily large quantities of electrons.
While power electronics are often held to be small stuff like regulators in a computer power supply or MOSFETs in a car stereo amplifier or even the IGBTs which turn on and off windings in elevator motors, real power electronics are generally bigger stuff than Radio Shack sells. Hockey-puck shaped SCRs which require water cooling when they're installed to control aluminum smelters. Or the stuff the power company uses. (Note that word again...)
In other words, stuff which can be compared to a 2N3055 in exactly the same way as you'd compare your Palm to a Cray.
I don't know if I agree with that or not. I do happen to remember my father adding aluminum foil, coat hangers, and various other sundries to our standard set top pair or rabbit ears to increase the reception. it wasn't rocket science. it wasn't science it all. it was trial and error.
Use a quality antenna... VHF TV channels 2-6 and 7-13 are in different parts of the spectrum; you cannot handle them efficiently with the same antenna... to say nothing of UHF. If it's a rod antenna (my favorites are 1/2 wave), make sure it's isolated from, but on, a good ground plane. Old BBQ grills work well for this at high frequencies, but remember that you want each side of your ground plane to be twice the length of the antenna - ie, one wavelength. Place the antenna up high. Make sure you polarize it the same way as the transmitter - AM/FM radio is usually vertically polarized, TV and SW radio are horizontal. Move the antenna away from all conductive objects (including drywall screws embedded in the walls). Replace 300 ohm twin-lead with 75 ohm coax by using a matching transformer right at the driven elements on the antenna. Beware of reflected radio waves coming off everything from wet trees to building walls. Orient the antenna to receive the strongest signal, whether it's the main signal or a reflection off a permanent object. Any other technique (ie. aluminum foil to unbalance the dipole) is a poor I-don't-care-if-I-lose-12dB-of-good-signal response to the problem. It may work in local areas with strong signals, but it's neither reliable nor efficient.
Among cheap antennas... UHF loops are great, if you use a UHF-capable matching tranformer to drive coax, and mount the loop far away from all conductive objects. Rabbit ears are junk and are really only good for strong reception areas, unless you place the ears horizontally at 180 degrees to each other, place it on a NON-conductive surface, and retract the telescopic elements to the right length for the frequency of the station you're trying to receive.
In short, if you know what you're doing, you'll avoid the aluminum foil and random chunks of coathanger. Math is your friend, and it will blow trial-and-error out of the water every time.
The standard Microsoft weenie excuse for instability in the past has been "it's the drivers!", blaming the video drivers is a favourite.
Unless it's an ATI product, in which case you can be 100% assured that it *is* the video drivers.
In my experience, you can bring any Windows 2000 or XP machine with any model of All in Wonder to a screeching blue HALT by simply doing such outlandish and unreasonable things as
And for those who really like fun, try an ATI All In Wonder Pro on Windows 2000. A couple of years ago, I deployed a couple of hundred of them at a Toronto TV station. A year later, they asked me to upgrade all their systems to Windows 2000. Constant random lockups of the whole system, requiring not just a reboot but a power cycle. Needless to say, they were not very pleased - you spend $300 on a video card, and you kind of expect that they'll provide drivers for at least a couple of years. ("They've been around forever. Besides, they're a good hometown company! Their headquarters are just 5 minutes from here, up the 404 in Markham."). Their news department almost did a story on crappy software but it was vetoed because news is supposed to be impartial.
As for ATI, I will never buy another ATI product ever again, for myself or for anyone else.
Yeah, so the deal is this site is essentially as it was back in 1993. I am recreating the whole site as we speak.
Keep a copy somewhere for an online museum!
Sorry... usually a site like that is designed by teenage girls using Geocities accounts to post tributes to their favorite teen idol. Flaming them for their animated GIFs, horrible background, and MIDI assaults when I accidentally happen onto their pages is, of course, pointless. I guess I had a lot of built-up tension. Sorry.
Ever heard the Growing Pains theme in MIDI? Urk. B.J. Thomas and Jennifer Warnes must not be impressed.
Even my little old G3 iMac is capable of handling quite a load from Slashdot and this site is serving up graphics intensive stuff.
I suspect, given the subject matter of your site, the chosen backgrounds and text colors are designed to test a theory that extreme garishness may cause blindness?
Mac people are supposed to have style!
Yeah, I've been hammered a few times with exactly the same effect. (Pentium 90, 48 megs RAM, simple dynamic content, Apache, Linux.) I believe the primary limitation in my case is the speed of my DSL (1200kbps/128kbps less PPPoE overheads); when I've been Slashdotted, I've checked my outbound traffic with iptraf and found that I'd maxed out my upload speed and page requests were occasionally timing out rather than melting down the server. (Though seeing literally nothing but CGI scripts and httpd daemons on top's display is exhilarating, almost as good as skydiving but not quite as good as a big-block V8 or sex.)
I'm sorry, but fox29 buffalo is crap, even when you don't need a huge antenna to get it.
Well, this is true. But I like the Sunday night line-up.
Up here in Canada, there's a CRTC (Canadian equivalent to FCC) rule that if an American channel and a Canadian channel are carrying the same show, the cable company has to switch and carry the Canadian station over the American one. Presumably to benefit Canadian broadcasters and advertisers.
Problem is that the Canadian stations are showing the same three episodes over and over, or without stereo sound, etc. They frequently forget to make the switch until about 10 minutes in, so you get to watch the opening of a new episode then miss out to a very tired re-run. The Simpsons became intolerable after the Apu-has-babies episode was run three times in three months while new episodes were on.
Just more protectionist bullcrap making me yearn for a Green Card.
I'm sure their success is attributed more to knowing what you are doing in a McGyver'ish way than simply hacking.
Yeah, antennas don't respond well to guesswork.
Most people don't know that an antenna rings electrically the way a tuning fork rings mechanically. There's only a very limited frequency range that an antenna will handle well.
On top of that, as the frequency increases, radio waves behave more and more like light. And problems like stray capacitance and stray inductance - tiny values in farads and henries - become very important design considerations as the frequency increases.
But a well-designed amateur antenna can be very capable. The radio waves don't care if you make the elements out of silver encrusted canine feces, if they're the right lengths.
UHF TV band, around 450MHz. Design is extremely critical here. But by doing a little math first, I designed and built a 12-element Yagi (looks like an ordinary rooftop TV antenna but with more elements) which is tuned to channel 29. It's very directional, meaning I have to be pointed within a few degrees of the transmitter. But I can also watch WUTV Fox 29 from Buffalo, in Ottawa Canada, without shelling out for cable. Cost? Scrap of wood, old coat hanger wire trimmed to within 1/16" of the design dimensions, plastic tubing and clips to hold the elements to the board, old 75-300 ohm matching transformer gutted for its balun and soldered directly to the driven elements and feeding coax. Essentially free. Not waterproof, so it lives in my attic.
Those are probably bogus emails to harvest valid emails to sell. Usually they put a 1x1px image in the mail so they know who read it and who did not, then they sell those addresses as "1million valid addresses, only $99.99!!!"
Now, I'm gonna sound like a luddite, but there's a good reason. I *hate* HTML e-mail.
Having said that, there are times when I'd like to be able to embed an image to be grabbed from a remote server so that I can determine when a user is online.
I've never looked into creating HTML e-mail more than idly playing with the settings in Eudora (yeah, I run Windows 2000 on my primary workstation, Linux and the BSDs on the others). It seems that Eudora 5.2 won't allow it, unless I'm missing something.
Any pointers?
How. I understand the area under a graph is the intergral of the formula of the graph, but if you have an everyday shape, chances are its not created by a known mathematical formula. how do you work out the area using calculus?
Ahh... Now we discover the joy of Infinite Series. Infinite series allows you to do all sorts of things to (arbitrary) precision. (Arbitrary in that it won't spit back an answer to 300 decimal places unless you make the program you write run through the loop 300 times...)
Basically, here's the idea. You can do a regression of the known points on the graph to come up with a function (formula) to describe the relationship. Regressions come from infinite series, but are used in a plug-and-play format in statistics courses. Also annoyingly, Excel 95 and up includes the capability to do them in the Data Analysis tools, OpenOffice does not yet [grumble grumble]. Anyway, once you have a function, you simply integrate it to find the area.
My favorite part of all this is that the series usually gives you a nice long sum of little polynomial expressions, which are individually and collectively easy to integrate.
Practical applications? Fourier Transforms and Fast Fourier Transforms. They allow you to express any function (audio waveform?) as a sum of different overlapping sinewaves. From there, you can do all the math you want on them. MP3 and Ogg codecs do this.
The best piece of advice I can give anyone trying to learn from a textbook is to tell them to work through the problems. Anyone should be able to pick up many of the textbooks listed below and work though as many of the problems as time allows (limited either by patience or by real life events). Most textbooks provide answers to selected problems, so you can check your progress.
Absolutely, 100%. Nobody is born with the ability to take a triple scalar product or multiply two matrices (both happening in your video card when you're playing Doom!). As a great Calculus teacher once announced to his class through a thick French Canadian accent, "Math is not a spectator sport." (Actually, it came out as "Matt ees not a spectator sport.")
Having said that, Calculus is my favorite kind of math. It's incredibly elegant and probably the most useful advanced math, as it touches everything you do. Consider your car. If you calculate your speed using a watch and the odometer, you have an idea how fast you were going, but your speedometer is actually showing you the value of the derivative at any instantaneous time. Your speedometer shows the rate of change of position (distance travelled) at any instantaneous time. That's calculus.
Don't be afraid. "Calculus" (besides being a formal term for tartar the dentist scrapes off your teeth) means small stones in Latin... small stones as used for counting.
Two *great* books on the subject:
Remember: Do the problems, succeed. Don't do the problems, fail. It's that simple.
The last thing, too.. Don't power anything like this (the pad or the fan) off a PS2 port. I think that most of them are fused for about 20-50mA at 5V. You'd be better off finding a mouse with a pair of extra wires and making a little adapter at the computer end to drop 5V or 12V from the power supply into the mouse. It might be a good idea to consider adding an inline fuse there, too. (If the dog eats the mouse, you don't want to lose your uptime record when the power supply cuts out.)
Now if only...
...he'd hooked the BreezePad up to the exhaust of a vacuum cleaner rather than a wimpy little computer fan.
HoverMouse, anyone?
I should try mousing on the air hockey table to see how slippery it is....
Seriously, too. To cut acrylic (or most other plastics) neatly, use masking tape along the line you're cutting (helps avoid chips). Don't use metalworking tools if you can avoid it, the teeth are too fine and get clogged. Saw *slowly* because the friction will melt the plastic. Pouring water (ie. from a garden hose) as you cut is good to wash away chips and keep the piece cool. Leave the paper backing on the plastic until you're done *all* the cutting and drilling. Deburr the holes by using a countersinking bit BY HAND for a couple of turns. And finally, always remember: measure once, cut twice! [grin]
If you need this to work with an optical mouse, make sure any LEDs in the pad are a very different color. Mine, for example, has a red LED and I'd imagine that its sensor is designed for that, so blue LEDs would probably upset it very little... but I haven't tested it.
Once you've got the cutting and drilling done, you could take off the paper backing and take the piece to a sandblasting shop and have them blast it gently with walnut shells or other soft blasting media. That should frost it nicely so that it works with an optical mouse, and the whole thing would glow, too.