However, if you add impurities to the water (mostly salts), it rapidly becomes conductive due to the free ions in salt.
Pure water is non-conductive, but you won't keep it that way. During my PhD research, I tried cooling an electromagnet with deionized water. It works for a while, but it doesn't stay deionized for long. Once it starts to turn, things get messy and as well as shorts, you get corrosion and other problems.
I ended up using paraffin, which I think you in the US call kerosine (not the stuff you put in aeroplanes!) It has a much lower heat capacity than water, but is at least easy to pump (I used a central heating centrifugal pump). It is not a fire hazard unless you make it into a fine mist or have something that could act as a wick.
Re:Where to put angular momentum
on
Hack in Space
·
· Score: 2, Interesting
Thanks for that. One question though. Where does the unwanted angular momentum come from? I would have expected that once things have settled down after release of the satellite, there would not be much in the way of sources of angular momentum to deal with. The impact of dust might possibly add some, but wouldn't this be negligible? I can't think of any other sources off the top of my head. Induced currents and magnetic fields would tend to damp any rotation. What am I missing? Maybe this satellite is in low-earth orbit and being 'buffetted' by the upper atmosphere...?
I'm still looking for a book on C++ written in an equivalent style to K&R. The example programs in all the C++ books I've ever seen are just too darned long. K&R manage to illustrate the essential points of C in snippets mostly of around 3 lines. No fluff and completely general. I'm not interested in examples that implement a whole program, because I can put the pieces together myself thankyou, once I understand what those pieces are. I don't want to have to spend more time trying to understand what a program does than I do understanding how it's expressed in the language when I'm learning a new language.
I think terse examples are far more educational than long 'real-world' examples. K&R's one-liner implementation of strcpy() is a perfect example. Once you understand why it works, you understand for loops, pointers, null-terminated strings, expression evaluation, post-increment, etc...
Of course it's broken in NS4. (Actually, I was surprised at how well NS4 did render it considering.) NS4 has very buggy stylesheet support. Remember this is a demo of a technology. If you were using it for real, you'd use one of the techniques mentioned earlier to hide the stylesheet from NS4, so everything would be hunkydory.
Good point about fixed font sizes. What is ironic, is that elsewhere ALA give a method that sets the font size in a consistent way using relative font sizing, so that the user can increase the font size with the browser font size control. You're quite right though – their site is non-resizable in Konqueror too. A quick glance at their stylesheet seems to suggest they are not practising what they preach for some reason. (Do as they say, but don't do as they do...)
BTW, if this is a frequent problem for you, you may benefit from looking into Mozilla. Mozilla allows you to resize text even when its size has been specified in absolute terms (e.g. px). Very useful. It also allows you to select alternate stylesheets where supplied, or even use your own.
Of course, you can always just turn off stylesheet support in your browser if you don't like it. Any standards-compliant page will divulge its content just fine sans-stylesheet.
Take a look at this, this and this for ideas about using CSS and honest-to-goodness standards-compliant no-frills HTML in a totally cross-browser fashion, and getting some really nice layouts into the bargain.
I'm not sure what the previous comment about webstandards.org wanting everyone to live on the bleeding edge of stylesheets was about, or if it was just plain wrong. The point of stylesheets is that when you use them properly, the page will display on any browser. Older browsers will just ignore the stylesheet and do a fine job of giving a mostly plain-text display. The only problem is a couple of mid-way browsers that think they understand stylesheets and don't. But there are techniques to avoid these problems.
To clarify gmack, a 64-bit integer on a 32-bit processor is treated as two 32-bit numbers. That means add, subtract, multiply, etc all require multiple operations.
I remember doing 16-bit arithmetic on the BBC micro, which used an 8-bit 6502 processor. Nothing wrong with it, but it is not nearly as efficient as native 16-bit arithemtic.
It's a nice idea. I wonder for how many programs it will work. I know one shouldn't but there are occasions when it's easier to write code that relies on integers overflowing in a certain way (and hence assumes they are a certain size). And what about C unions/structures where you assume you know the size of the various elements?
We'll all need 64-bit before Tue Jan 19 03:14:07 2038.
That's when the 32-bit integer number of seconds since epoch 1970 used for time-processing on almost all UNIX-like systems hits the limit. Still, no-one will still be using 32-bit systems by then, will they? Er, right.
As [various parties] have belatedly grown interested in controlling networked computing..., battles over censorship and content... have raged throughout cyberspace. That's why Chicago artist Antonio Muntadas' website "The File Room" may be one of the most significant sites ever created on the Web.
Is it just me or was that just a bit of a non-sequitur? I can't see anything more here than the assertion that censorship (and therefore a website about it) is one of the most significant issues on the web.
This argument seems to be self-defeating, since the author himself asserts that censorship on the web can't succeed. It's just not a big deal. Is it really that important for everyone to be able to say whatever they want? What about if you don't have access to the web? Or what about if you can say what you want, but no one else ever hears you? (Ironically, this comment could be modded down to -1 - I would still have so-called 'free speech', but chances are no one would hear me.) I don't think the reality lives up to the hype. And I don't think it really matters.
Unfortunately, not everyone is so lucky. Environmental disasters inevitably hit the world's poorest the hardest, in countries with underdeveloped infrastructure and emergency relief services. I've summarised the following from the most recent edition of "Tear Times", the magazine of the charity Tearfund.
The 1990s saw 87 natural disasters, compared to 20 in the 1950s. The world's poor often have to live in the most dangerous places: river banks, flood plains and cyclone areas. They have no access to modern construction methods that protect against severe weather.
Nur Mohammed used to live with his family on the beach at Hatiya Island in the Bay of Bengal. He survived on fishing and could not afford to move elsewhere. Three months later, the place where his shack used to be is another kilometer out to sea.
65 Bangladeshi families live in a certain village on the banks of the Brahmaputra River. Each year the village floods to six feet and the water remains for 6 months. Many die from malaria. 'If I had the chance to go somewhere else I would', says Anwar Islaam. 'This is worse than before.'
It's the West that produces most of the CO2 emissions. The West can probably cope with more storms and sealevel rise. The innocent poor cannot.
... to determine the practicality of creating human colonies on other planets. If water and life are common, then the entire idea becomes far more practical.
If life already exists on other planets, we should leave them alone. Humankind has enough of a bad track-record of screwing up one planet – sending countless species into extinction and precipitating environmental melt-down.
Only if a planet is proven to be free from life should we consider colonising it.
Does it need really to be on 24x7?
on
Mini-PC w/o Fans?
·
· Score: 2, Informative
You mention that it needs to be on 24x7, but is this because it will be working all that time, or because you don't want to wait for it to boot up each time you come to it?
I put my desktop PC to sleep whenever I'm not sitting at it. In sleep mode the disk spins down and the fan slows right down so it is completely silent. It takes about 2 seconds to wake up when I jog the mouse. This may be worth considering.
If it's got to respond to other stimuli, e.g. an incoming call on the modem, a network request, cron, etc, you may even be able to make it wake up temporarily, deal with the request, and then go back to sleep, perhaps even without needing to start up the fan or disk. I haven't worked out how to do this yet (APMS doesn't seem as configurable as I hoped), but it is my aim.
But there is still the issue of trust for those sysadms using the block lists. They presumably trust the list maintainer or they wouldn't be using the list.
This trust is important, because it is what makes it worthwhile to use the list. If a sysadm didn't trust the list maintainer, they would have to verify the list themselves, which means they might as well compile their own.
The problem with making the list maintainer anonymous and unaccountable (by which I mean they don't answer to anybody – no one can bring them back into line if they start getting it wrong) is that sysadms won't necessarily know that there is a problem and therefore that they should stop using the list.
The article mentions that some of these 'spam cops' are only contactable via a newsgroup, and that they hide their real identities in order to avoid being hassled by lawyers employed by the spammers. I understand this. I applaud what they are doing - I despise spam as much as the next person.
But by their anonymity, they make themselves unaccountable to anyone else. That means that there are no real controls. What happens if one of these spam cops ends up on some kind of ego trip, or perhaps just starts making mistakes? A breakdown in relationships or other pressures could result in a block list not being updated.
Much as it may be difficult, I think all efforts to control spam must be made out in the open, with full accountability to the rest of the internet community.
I was thinking more of 'marketing' as information, rather than marketing as hard-sell. (I personally wish all advertising was informational rather than persuasive.)
Referring back to the original story - my biggest complaint is that usually I can't find what I want, only what the marketer hopes I want. If the marketer knew more about me (e.g. by studying my browsing history), he might be able to tell me the things I really want to know, rather than spamming me with things I'm not interested in.
It's to the marketer's advantage to do this. We're talking about targetted selling, but done much better than it is at present (if that's possible).
Joking aside, I think this touches on a key point. It's not whether they have the information, but what they choose to do with it.
I don't particularly care if an ISP is logging my every move, as long as they don't use this information to as an excuse to send me more uninteresting junk email than they do already. Which is odd really, because I would have thought they would be more likely to send me offers I am interested in if they know what sort of things interest me.
Let's face it - most advertising these days is rubbish. I almost never see an ad that tells me something I really wanted to know. Leaflets dropped through my door are never to sell something I actually want. I don't want a new patio, factory price clothing, etc. I do want to know where locally I can buy a universal 6V power supply with built in NiMH battery charger (for example).
I know advertising isn't the only issue. But my point is that I am not really bothered about what information is stored about me - only about how it is used. If it is used well, it could be to my benefit.
Most of us don't even use a tripod, let alone large-format film. For a normal hand-held shot with normal consumer film, his comparisons are not really valid.
I was trying out my new digital camera last Saturday for the first time, taking photos from the top of the London Eye of the city at dusk. Early on, there was too much contrast between the bright sky and the dark Palace of Westminster. I took two photos, one with auto exposure (sky ok, building too dark) and one 'overexposed' by about 2 stops. When I got home, I was able to combine the two in the GIMP.
I ended up with a much greater total tonal range than either of the individual images.
This experiment was done hand-held. I imagine that with a tripod and by doing the maths properly when combining the images, one could achive the same or even greater dynamic range than conventional film.
Incidently, displaying images on a CRT generally exaggerates the contrast. Compressing the raw values from the camera ought to counteract this effect, so would be a Good Thing just on its own. Of course, you have to take into account gamma curves too. As I said, you'd need to do the maths to do it properly.
'Drivelling Slashdotters' is a world-first experiment into artificial evolution - a culmination of four and a half years research by CmdrTaco and his team. The colony is divided into two species: Moderators and Posters. The Posters have one goal: to obtain enough karma to sound off about anything without being moderated into obscurity. Moderators feed off Posters by stalking down trolls, first posts, and anything vaguely factual, and sucking off score points.
In place of erudite discourse, the groundbreaking technology used in slashdot.org will be demonstrated to guests in a spectacular live-action show - complete with more-heat-than-light, flames, and random musings. Guests will witness Slashdotters in their natural environment, fighting for survival, learning and evolving as time goes on. Or not.
Each show will begin in darkness, and remain in darkness. Initially, a 'First Post' will appear. This simple creature is controlled by an 'artificial moron network', and it posts for no apparent reason.
Then a Moderator will appear. This is higher up the food chain than the Poster, and survives by feeding its ego off the Posters. The Moderator will immediately mod down the Poster. This is instinct, not reason.
Slashdot Mirror
NeXT, and it's OS failed because of market and pricing issues, not technical or ascetic ones
I thought 'ascetic' issues would only concern those still using the command line 8-)
However, if you add impurities to the water (mostly salts), it rapidly becomes conductive due to the free ions in salt.
Pure water is non-conductive, but you won't keep it that way. During my PhD research, I tried cooling an electromagnet with deionized water. It works for a while, but it doesn't stay deionized for long. Once it starts to turn, things get messy and as well as shorts, you get corrosion and other problems.
I ended up using paraffin, which I think you in the US call kerosine (not the stuff you put in aeroplanes!) It has a much lower heat capacity than water, but is at least easy to pump (I used a central heating centrifugal pump). It is not a fire hazard unless you make it into a fine mist or have something that could act as a wick.
Thanks for that. One question though. Where does the unwanted angular momentum come from? I would have expected that once things have settled down after release of the satellite, there would not be much in the way of sources of angular momentum to deal with. The impact of dust might possibly add some, but wouldn't this be negligible? I can't think of any other sources off the top of my head. Induced currents and magnetic fields would tend to damp any rotation. What am I missing? Maybe this satellite is in low-earth orbit and being 'buffetted' by the upper atmosphere...?
I'm still looking for a book on C++ written in an equivalent style to K&R. The example programs in all the C++ books I've ever seen are just too darned long. K&R manage to illustrate the essential points of C in snippets mostly of around 3 lines. No fluff and completely general. I'm not interested in examples that implement a whole program, because I can put the pieces together myself thankyou, once I understand what those pieces are. I don't want to have to spend more time trying to understand what a program does than I do understanding how it's expressed in the language when I'm learning a new language.
I think terse examples are far more educational than long 'real-world' examples. K&R's one-liner implementation of strcpy() is a perfect example. Once you understand why it works, you understand for loops, pointers, null-terminated strings, expression evaluation, post-increment, etc...
Edge.
That sorts the men from the boys - CSS-wise anyway.
Of course it's broken in NS4. (Actually, I was surprised at how well NS4 did render it considering.) NS4 has very buggy stylesheet support. Remember this is a demo of a technology. If you were using it for real, you'd use one of the techniques mentioned earlier to hide the stylesheet from NS4, so everything would be hunkydory.
Good point about fixed font sizes. What is ironic, is that elsewhere ALA give a method that sets the font size in a consistent way using relative font sizing, so that the user can increase the font size with the browser font size control. You're quite right though – their site is non-resizable in Konqueror too. A quick glance at their stylesheet seems to suggest they are not practising what they preach for some reason. (Do as they say, but don't do as they do...)
BTW, if this is a frequent problem for you, you may benefit from looking into Mozilla. Mozilla allows you to resize text even when its size has been specified in absolute terms (e.g. px). Very useful. It also allows you to select alternate stylesheets where supplied, or even use your own.
Of course, you can always just turn off stylesheet support in your browser if you don't like it. Any standards-compliant page will divulge its content just fine sans-stylesheet.
Take a look at this, this and this for ideas about using CSS and honest-to-goodness standards-compliant no-frills HTML in a totally cross-browser fashion, and getting some really nice layouts into the bargain.
I'm not sure what the previous comment about webstandards.org wanting everyone to live on the bleeding edge of stylesheets was about, or if it was just plain wrong. The point of stylesheets is that when you use them properly, the page will display on any browser. Older browsers will just ignore the stylesheet and do a fine job of giving a mostly plain-text display. The only problem is a couple of mid-way browsers that think they understand stylesheets and don't. But there are techniques to avoid these problems.
I'm certain that this is the way forwards.
To clarify gmack, a 64-bit integer on a 32-bit processor is treated as two 32-bit numbers. That means add, subtract, multiply, etc all require multiple operations.
I remember doing 16-bit arithmetic on the BBC micro, which used an 8-bit 6502 processor. Nothing wrong with it, but it is not nearly as efficient as native 16-bit arithemtic.
It's a nice idea. I wonder for how many programs it will work. I know one shouldn't but there are occasions when it's easier to write code that relies on integers overflowing in a certain way (and hence assumes they are a certain size). And what about C unions/structures where you assume you know the size of the various elements?
What other gotchas are there to look out for?
We'll all need 64-bit before Tue Jan 19 03:14:07 2038.
That's when the 32-bit integer number of seconds since epoch 1970 used for time-processing on almost all UNIX-like systems hits the limit. Still, no-one will still be using 32-bit systems by then, will they? Er, right.
As [various parties] have belatedly grown interested in controlling networked computing..., battles over censorship and content ... have raged throughout cyberspace. That's why Chicago artist Antonio Muntadas' website "The File Room" may be one of the most significant sites ever created on the Web.
Is it just me or was that just a bit of a non-sequitur? I can't see anything more here than the assertion that censorship (and therefore a website about it) is one of the most significant issues on the web.
This argument seems to be self-defeating, since the author himself asserts that censorship on the web can't succeed. It's just not a big deal. Is it really that important for everyone to be able to say whatever they want? What about if you don't have access to the web? Or what about if you can say what you want, but no one else ever hears you? (Ironically, this comment could be modded down to -1 - I would still have so-called 'free speech', but chances are no one would hear me.) I don't think the reality lives up to the hype. And I don't think it really matters.
Well, that's good news for NYC cormorants.
Unfortunately, not everyone is so lucky. Environmental disasters inevitably hit the world's poorest the hardest, in countries with underdeveloped infrastructure and emergency relief services. I've summarised the following from the most recent edition of "Tear Times", the magazine of the charity Tearfund.
The 1990s saw 87 natural disasters, compared to 20 in the 1950s. The world's poor often have to live in the most dangerous places: river banks, flood plains and cyclone areas. They have no access to modern construction methods that protect against severe weather.
Nur Mohammed used to live with his family on the beach at Hatiya Island in the Bay of Bengal. He survived on fishing and could not afford to move elsewhere. Three months later, the place where his shack used to be is another kilometer out to sea.
65 Bangladeshi families live in a certain village on the banks of the Brahmaputra River. Each year the village floods to six feet and the water remains for 6 months. Many die from malaria. 'If I had the chance to go somewhere else I would', says Anwar Islaam. 'This is worse than before.'
It's the West that produces most of the CO2 emissions. The West can probably cope with more storms and sealevel rise. The innocent poor cannot.
... to determine the practicality of creating human colonies on other planets. If water and life are common, then the entire idea becomes far more practical.
If life already exists on other planets, we should leave them alone. Humankind has enough of a bad track-record of screwing up one planet – sending countless species into extinction and precipitating environmental melt-down.
Only if a planet is proven to be free from life should we consider colonising it.
You mention that it needs to be on 24x7, but is this because it will be working all that time, or because you don't want to wait for it to boot up each time you come to it?
I put my desktop PC to sleep whenever I'm not sitting at it. In sleep mode the disk spins down and the fan slows right down so it is completely silent. It takes about 2 seconds to wake up when I jog the mouse. This may be worth considering.
If it's got to respond to other stimuli, e.g. an incoming call on the modem, a network request, cron, etc, you may even be able to make it wake up temporarily, deal with the request, and then go back to sleep, perhaps even without needing to start up the fan or disk. I haven't worked out how to do this yet (APMS doesn't seem as configurable as I hoped), but it is my aim.
Thank you. That's reassuring.
But there is still the issue of trust for those sysadms using the block lists. They presumably trust the list maintainer or they wouldn't be using the list.
This trust is important, because it is what makes it worthwhile to use the list. If a sysadm didn't trust the list maintainer, they would have to verify the list themselves, which means they might as well compile their own.
The problem with making the list maintainer anonymous and unaccountable (by which I mean they don't answer to anybody – no one can bring them back into line if they start getting it wrong) is that sysadms won't necessarily know that there is a problem and therefore that they should stop using the list.
The article mentions that some of these 'spam cops' are only contactable via a newsgroup, and that they hide their real identities in order to avoid being hassled by lawyers employed by the spammers. I understand this. I applaud what they are doing - I despise spam as much as the next person.
But by their anonymity, they make themselves unaccountable to anyone else. That means that there are no real controls. What happens if one of these spam cops ends up on some kind of ego trip, or perhaps just starts making mistakes? A breakdown in relationships or other pressures could result in a block list not being updated.
Much as it may be difficult, I think all efforts to control spam must be made out in the open, with full accountability to the rest of the internet community.
I was thinking more of 'marketing' as information, rather than marketing as hard-sell. (I personally wish all advertising was informational rather than persuasive.)
Referring back to the original story - my biggest complaint is that usually I can't find what I want, only what the marketer hopes I want. If the marketer knew more about me (e.g. by studying my browsing history), he might be able to tell me the things I really want to know, rather than spamming me with things I'm not interested in.
It's to the marketer's advantage to do this. We're talking about targetted selling, but done much better than it is at present (if that's possible).
Joking aside, I think this touches on a key point. It's not whether they have the information, but what they choose to do with it.
I don't particularly care if an ISP is logging my every move, as long as they don't use this information to as an excuse to send me more uninteresting junk email than they do already. Which is odd really, because I would have thought they would be more likely to send me offers I am interested in if they know what sort of things interest me.
Let's face it - most advertising these days is rubbish. I almost never see an ad that tells me something I really wanted to know. Leaflets dropped through my door are never to sell something I actually want. I don't want a new patio, factory price clothing, etc. I do want to know where locally I can buy a universal 6V power supply with built in NiMH battery charger (for example).
I know advertising isn't the only issue. But my point is that I am not really bothered about what information is stored about me - only about how it is used. If it is used well, it could be to my benefit.
How many of you can fill a 256MB compact flash card on a single set of batteries?
Heck, we need better batteries too. 4 weeks continuous use on a set of AA NiMHs?
Most of us don't even use a tripod, let alone large-format film. For a normal hand-held shot with normal consumer film, his comparisons are not really valid.
I was trying out my new digital camera last Saturday for the first time, taking photos from the top of the London Eye of the city at dusk. Early on, there was too much contrast between the bright sky and the dark Palace of Westminster. I took two photos, one with auto exposure (sky ok, building too dark) and one 'overexposed' by about 2 stops. When I got home, I was able to combine the two in the GIMP.
I ended up with a much greater total tonal range than either of the individual images.
This experiment was done hand-held. I imagine that with a tripod and by doing the maths properly when combining the images, one could achive the same or even greater dynamic range than conventional film.
Incidently, displaying images on a CRT generally exaggerates the contrast. Compressing the raw values from the camera ought to counteract this effect, so would be a Good Thing just on its own. Of course, you have to take into account gamma curves too. As I said, you'd need to do the maths to do it properly.
'Drivelling Slashdotters' is a world-first experiment into artificial evolution - a culmination of four and a half years research by CmdrTaco and his team. The colony is divided into two species: Moderators and Posters. The Posters have one goal: to obtain enough karma to sound off about anything without being moderated into obscurity. Moderators feed off Posters by stalking down trolls, first posts, and anything vaguely factual, and sucking off score points.
In place of erudite discourse, the groundbreaking technology used in slashdot.org will be demonstrated to guests in a spectacular live-action show - complete with more-heat-than-light, flames, and random musings. Guests will witness Slashdotters in their natural environment, fighting for survival, learning and evolving as time goes on. Or not.
Each show will begin in darkness, and remain in darkness. Initially, a 'First Post' will appear. This simple creature is controlled by an 'artificial moron network', and it posts for no apparent reason.
Then a Moderator will appear. This is higher up the food chain than the Poster, and survives by feeding its ego off the Posters. The Moderator will immediately mod down the Poster. This is instinct, not reason.
And so the show goes on... and on...
(No offence intended...)
I should have said no physical breeding/evolution/natural selection.