Some biggies I use all the time, but haven't seen mentioned here, are Levenberg-Marquardt (sp?) (non-linear model fitting through chi-squared minimization) and Powell's direction set method (optimization). And biconjugate gradient methods for solving large sparse linear systems. Also we shouldn't take for granted Tchebychev methods, which are the magic behind fast accurate implementation of special functions like exp and sin.
This may be a bit of a stretch -- but I have to mention the Beowulf algorithm: fill a room with cheap PCs, string together with scrounged network hardware, add Linux and MPI/PVM, and poof, you have a supercomputer.
That original list of 10 certainly hit the war-horses -- Monte-Carlo, matrix decomposition, FFT -- without which life would be nasty, brutish, and short.
This article was interestingly devoid of information. Let's us know they're really simple, e.g.:
The Daubechies wavelets turn the theory into a practical tool that can be easily programmed and used by any scientist with a minimum of mathematical training.
But apparently not so simple they could explain any of it to us blockheads.
Anybody know where you could find a introduction to this subject that actually introduces it?
Perhaps I'm beating a dead horse here, but spinning a disk at constant speed does not eat up any power. (Or whatever power it takes is due to imperfections in the bearings.)
I wonder, do you know of any actual verified examples of improved precision machining in zero g? Only one I recall hearing of was high precision ball bearings, which at last news never worked out.
Let me give you an example of a practical application of this technology.
Take a wheel, with the axle horizontal and place the axle directly over the edge of this thing, so half the wheel has its gravity reduced, and the other half doesn't. Then there is a net torque on the wheel. It will spin. You can put a generator on the axle and make free energy for nothing.
In other words, if this thing works, you can make a perpetual motion machine. You can interpret that fact any way you want -- I interpret it to mean this anti-gravity thing is a crock of shit.
This has been going on for a while. See the most recent note on this subject from Bob Park's "What's New." He refers to an earlier $2M that got dropped on this crackpottery.
Re:Cost of Repairs vs. Relaunch vs. Reentry
on
NASA Satellite Stranded
·
· Score: 3, Informative
Well, NASA has 3 choices Re-entry, Retrieve and Relauch, or Repair.
I fear this post has missed an essential point -- as the article makes clear, this isn't NASA's problem, it's Boeing's problem. NASA doesn't pay for the thing and doesn't own it until it's in the right orbit.
When the price of getting up there gets to $2,000(due to some new form of propulsion likely) then we'll see great strides such as Space Station wheels...
Yes, it will be a great advance when we can get wheels on the Space Station. Those oxen dragging it along on skids just isn't very efficient.
I thought that all light bulbs are designed to die after a certain amount of use.
Seems like a rather negative way of looking at it -- I'd say they're designed to go on working for a certain amount of use. And it's a miracle of engineering that incandescent bulbs last as long as they do. When you flip that switch an incandescent bulb filament ramps from room temperature to several thousand degrees in a fraction of a second. They had to refine the design to withstand this severe thermal cycling as many times as possible before it breaks. And they have to restrict the materials to ones that not only won't melt at that temperature, but that evaporate slowly enough. The evaporation thing is a particular problem -- not only does it eat into the filament, but said metal winds up condensed on the glass envelope, which keeps the light from getting out.
I don't think the incandescent bulb is a good candidate for significant improvement. It's a crude idea, and it's a miracle that they kept it from going obsolete this long.
First part of the plan is make up a bunch of bullshit exaggerating the likelihood of Earth being destroyed by an asteroid. As you see, this part of the plan is pretty much in place.
Next part of the plan is to absorb as much tax money as possible for projects to track asteroids that come anywhere near Earth. This is also going nicely.
And the final part of the plan is start really sucking up the tax money with schemes for doing something about it -- usually coming from the same people who brought you SDI. And this makes a lot of sense -- many of the stupid ideas that could never stop a missile are equally applicable to asteroids.
Funny you should say that. Some years back, well before Iridium went belly up, I called them to find out what it would cost to use Iridium for command and telemetry to an Antarctic balloon payload we were building. What I got was the runaround, and a general sense that they thought it odd and annoying that somebody actually wanted to use their service.
Frinstance, those small lightweight headphones that you use with your walkman were a miraculous innovation about 20 years ago, and what made them possible was advances in magnet technology. Before that, headphones of that quality weighed a couple pounds.
Right now, electric motors for e.g. hybrid vehicles could really use better magnets. Pull out your McMaster-Carr and see what a 200 horse high starting torque DC motor weighs, and how big it is. It's impressive.
At least one thing about this story is full of crap. The article quotes the guy saying "Hubble's UV detectors are not solar-blind" -- this would be false. One of the detectors in the newly installed ACS is called the Solar Blind Channel (SBC). Can you guess why it's called that? In addition, two UV detectors in STIS, which was installed in 1997, are solar-blind.
Re:International Impact
on
SSSCA Hearing
·
· Score: 1
Don't get too comfortable just because you don't live in the US. Due to the modern miracle of free trade treaties e.g. GATT, any stupid new legislation affecting commerce sooner or later becomes a stupid new requirement on all signatory nations.
I'm all for free trade, but I can't help noticing that a smelly byproduct is what amounts to a new layer of global government that is orders of magnitude less responsive and accountable that our already incredibly unresponsive and unaccountable national governments.
You can find the quote here, from the PMRC hearings:
I have a hard time understanding it. Paul, since I traveled the country for 3 years, they said they could not understand me. Maybe I
could make a good rock star. I do not know.
I have no earthly idea what he's talking about. The man is a loon.
I believe this article is not talking about monocrystalline alumina, the novelty being getting transparency in polycrystalline alumina. Folks have of course been making transparent monocrystalline alumina aka ruby/sapphire for years.
But while we're on the subject, I did my grad school work with a maser that used synthetic ruby. Had four pieces, each about 2mm x 4mm x 150 mm. I believe the set cost about $5000, and were made from a boule about 20 mm in diameter. So as gems go, these things aren't all that expensive.
We also used sapphire washers a few places -- sapphire is both an electrical insulator and a good thermal conductor (below 100K), a rare combination. I'll never forget the time I caught an undergrad throwing one in the trash. He thought it was plastic -- he just about lost it when I told him it was sapphire.
"A filter that blocks out bright light"? Sometimes it's difficult finding the connection between CNN science news and reality.
Serious space junkies will want to check out the SM3B web site. In particular has lots of tech info about the stuff getting installed, and for your idle moments has webcams viewing the clean room and launch pad.
Slashdot Mirror
This may be a bit of a stretch -- but I have to mention the Beowulf algorithm: fill a room with cheap PCs, string together with scrounged network hardware, add Linux and MPI/PVM, and poof, you have a supercomputer.
That original list of 10 certainly hit the war-horses -- Monte-Carlo, matrix decomposition, FFT -- without which life would be nasty, brutish, and short.
Anybody know where you could find a introduction to this subject that actually introduces it?
Perhaps I'm beating a dead horse here, but spinning a disk at constant speed does not eat up any power. (Or whatever power it takes is due to imperfections in the bearings.)
I wonder, do you know of any actual verified examples of improved precision machining in zero g? Only one I recall hearing of was high precision ball bearings, which at last news never worked out.
Take a wheel, with the axle horizontal and place the axle directly over the edge of this thing, so half the wheel has its gravity reduced, and the other half doesn't. Then there is a net torque on the wheel. It will spin. You can put a generator on the axle and make free energy for nothing.
In other words, if this thing works, you can make a perpetual motion machine. You can interpret that fact any way you want -- I interpret it to mean this anti-gravity thing is a crock of shit.
This has been going on for a while. See the most recent note on this subject from Bob Park's "What's New." He refers to an earlier $2M that got dropped on this crackpottery.
I fear this post has missed an essential point -- as the article makes clear, this isn't NASA's problem, it's Boeing's problem. NASA doesn't pay for the thing and doesn't own it until it's in the right orbit.
Yes, it will be a great advance when we can get wheels on the Space Station. Those oxen dragging it along on skids just isn't very efficient.
Seems like a rather negative way of looking at it -- I'd say they're designed to go on working for a certain amount of use. And it's a miracle of engineering that incandescent bulbs last as long as they do. When you flip that switch an incandescent bulb filament ramps from room temperature to several thousand degrees in a fraction of a second. They had to refine the design to withstand this severe thermal cycling as many times as possible before it breaks. And they have to restrict the materials to ones that not only won't melt at that temperature, but that evaporate slowly enough. The evaporation thing is a particular problem -- not only does it eat into the filament, but said metal winds up condensed on the glass envelope, which keeps the light from getting out.
I don't think the incandescent bulb is a good candidate for significant improvement. It's a crude idea, and it's a miracle that they kept it from going obsolete this long.
Could this story possibly be any more pointless? And what the hell is it doing in the science section?
Yes. Zero.
Let me set your mind at rest. There are no 8000 km wide asteroids. That would be bigger than three of the nine planets. We would have noticed.
First part of the plan is make up a bunch of bullshit exaggerating the likelihood of Earth being destroyed by an asteroid. As you see, this part of the plan is pretty much in place.
Next part of the plan is to absorb as much tax money as possible for projects to track asteroids that come anywhere near Earth. This is also going nicely.
And the final part of the plan is start really sucking up the tax money with schemes for doing something about it -- usually coming from the same people who brought you SDI. And this makes a lot of sense -- many of the stupid ideas that could never stop a missile are equally applicable to asteroids.
Funny you should say that. Some years back, well before Iridium went belly up, I called them to find out what it would cost to use Iridium for command and telemetry to an Antarctic balloon payload we were building. What I got was the runaround, and a general sense that they thought it odd and annoying that somebody actually wanted to use their service.
Right now, electric motors for e.g. hybrid vehicles could really use better magnets. Pull out your McMaster-Carr and see what a 200 horse high starting torque DC motor weighs, and how big it is. It's impressive.
At least one thing about this story is full of crap. The article quotes the guy saying "Hubble's UV detectors are not solar-blind" -- this would be false. One of the detectors in the newly installed ACS is called the Solar Blind Channel (SBC). Can you guess why it's called that? In addition, two UV detectors in STIS, which was installed in 1997, are solar-blind.
I'm all for free trade, but I can't help noticing that a smelly byproduct is what amounts to a new layer of global government that is orders of magnitude less responsive and accountable that our already incredibly unresponsive and unaccountable national governments.
But while we're on the subject, I did my grad school work with a maser that used synthetic ruby. Had four pieces, each about 2mm x 4mm x 150 mm. I believe the set cost about $5000, and were made from a boule about 20 mm in diameter. So as gems go, these things aren't all that expensive.
We also used sapphire washers a few places -- sapphire is both an electrical insulator and a good thermal conductor (below 100K), a rare combination. I'll never forget the time I caught an undergrad throwing one in the trash. He thought it was plastic -- he just about lost it when I told him it was sapphire.
Serious space junkies will want to check out the SM3B web site. In particular has lots of tech info about the stuff getting installed, and for your idle moments has webcams viewing the clean room and launch pad.