" the best way to build a skyscraper is not to use CAD programs at all, but a slide rule and pen'n'paper, which force you to think about what you're doing instead of making mistakes and 'correcting them later'."
Except that using a CAD program forces yyou to draw to scale. I've seen a surprising number of hand drawings which have two bolts intersecting.
Using tools is supposed to prevent stupid mistakes, allowing you to concentrate on preventing smart mistakes. If your debugger doesn't fall into this category, then something needs to be fixed.
I hope this is not too picky, but both your examples of poor design are examples of the discovery of a previously unknown engineering phenomenon. In the case of the Tacoma narrows it's vortex shedding, and in the case of the Millineum bridge, a resonant evvect caused by people walking in step with the current vibration. It's rather like discovering that on the trillion-and-first iteration, your CPU explodes. It sucks, but it's not a case of poor planning.
Which systems, exactly? I work in a research institution, and we use both Suns and PCs, and every one of our benchmarks that I've seen show that, at any given time, a high end PC (Redhat) beats out a high end Sun (Solaris) workstation for the 3 main CFD codes we use (CPU intensive tasks).
We still buy Sun, for ease of administration, reliability and warranty, but not for speed (or speed/cost ratio).
What the ancient Greeks called democracy, and what we call democracy are two different beasts. It's all in what you define as a citizen. In ancient Greece, you could vote so long as you were male, greek, and rich. That sounds more like an aristocracy than a democracy to me. Your assumption that all democracies are equal is ill-founded.
One of the major strategies to get any complex project to work is to use off the shelf parts. For physical engineering, those parts are defined by standards, and their properties are well known _and_documented_. For instance if I want an M10*1.5 socket head cap screw of strength rating 8.8, the properties of that piece are very well documented.
The problem with software engineering is roughly the same as if you made a bridge with every bolt individually hand made. It's a quality control problem.
Physical engineering generally does the same thing as code building, use standard parts to build a variation on a theme. Creativity in the selection of standard parts will end up in an end product of unknown quality.
It's not that creativity doesn't play a role, more that it shouldn't play as much of a role if quality product is to be made.
Generally the waste product of burning H20 and air at high temperature also include OH, NO, NO2, CO, H202, HCN, and about every other combination of O, H, N and C, your imagination can supply. The quantities of these other factors are dependant on temperature and pressure, so the amounts of these other things should be small in a fuel cell, so long as temperatures are kept down.
Here's an interesting piece of math. Take the worst case: You have 32 pieces, therefore, at each move there are 32 factorial board arrangements. =2.6e35 positions Assume 50 moves =1.32e37 positions
How do you get out of this more moves than molecules in the universe?
Which is not to say that there are not problems with the current peer review system. The current pressure to publish, means that the requirement that the published results should be original can get softened. The outcome is then more papers, with the same amount of scientific work.
If Schön was putting out 30 essentially similar papers per year, then the peer review process may have been failing to ensure that each paper had sufficient new material to warrant publication.
On a lighter note, I've always found that this pretty much summarises my idea of experimental physics.
The answer to any question, "Why wouldn't a custom *** be cheaper than a kludged job?" is: The rule of thumb is custom jobs cost 10-100 times per unit what a mass production product costs. Do you think they can make walkmans for 1/10 to 1/100 of the current prices?
Re:With enough storage, Chess could be solved too.
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In addition, even if you assume 2e44 possible positions (64!-40!)*50 moves, you've still got storage which weighs less than the earth.
Re:With enough storage, Chess could be solved too.
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Here's an interesting piece of math. 5.26e36 bits assume each bit can be represented in 5 atoms of silicon. 5 moles of silicon=3.01e24 bits=0.14 kg 5.26e36 bits= 2e11 kg The mass of the earth is 6e24kg, so you're much smaller than the earth. Since the density of silicon is 2330 kg/m^3, this mass is 1e8 m^3, or a cube of silicon 472m on a side.
The trouble is, that the niche between laptop and desktop is not really addressed. A lot of people (me too), would like a protable system, but do not need mobile computing. We're therefore reluctant to shell out big bucks, and sacrifice performance for a property we don't need.
Say I have a screen and keyboard in the office, and at home. I could pay â2500 for a top-end laptop with limited performance, or â1500 for a portable which screams. The problem, however is that the portable is not available.....yet.
Or with a science degree you'd know that as energy goes with the square of velocity, that the car is producing 9 times the energy (ignoring drag), and I doubt if it has a very different mass to the original, so the batteries have 9 times the energy densities of the old cells. Take your pick as to whether this is 18 or 81 times better than the original.
This is why scientists only trust liberal arts students to do simple maths like adding up McDonalds orders, or balancing the budget.
As an Australian (briefly overseas) I'd have to say that the fact that I don't know anyone with a minidisc player, and have only rarely seen portable players being used, that the format is not popular there. Maybe I just know too many people with CD burners.
Mach 4 at 1 bar doesn't have the same heat load as Mach 7 at 0.02 bar. And you need to be going faster than your cruising speed anyway if you want to launch from a rail gun.
That is really the core of the problem. If its a missile, the engine can be sacrificed, so it doesn't really need to slow down at its destination, but a non-ballistic missile does need guidance, which is a challenge. The idea is that it would be superior to a rocket because it would be only 35% of the takeoff weight for the same payload. Launching civilian payloads to space is probably the best goal. It's not like the world desparately needs more methods of raining down destruction.
No, actually you can work it out. The speed of sound in a gas in meters per second is equal to sqrt(ratio_of_specific_heats*8.314*Temperature/mas s_of_one_mole_in_kg) The only pressure dependance is a very small one, through the ratio of specific heats. Basically the speed of sound in a gas is independant of pressure and density.
This is true in a closed system, without heat addition. This is not the atmosphere. In the atmosphere the Pressure dropps off logarithmically, but the temperature makes a kind of sinusoid.
Maybe... Say a missile is cruising at Mach 8, and Altitude 35km. The weak Mach angle is then 7 degrees, meaning that the missile would have gone 280km past the sensor before it was detected, now extend that to Mach 20 and 50km altitude, and you're up to 1000 km past the sensor.
If the fuel burned, of course thrust was achieved. However, to answer your real question, this engine was not designed to produce net thrust. It was designed to achieve supersonic combustion within the simplest possible configuration
Actually for Hyshot, the design temperature was 220 Kelvin. A weather balloon was sent up beforehand, to make sure that the air wasn't so cold as to suppress combustion.
The Mach number is a similarity parameter. That is, all craft travelling at Mach 7.6 experience similar problems, regardless of the actual speed. Other similarity parameters include the Prandtl, Reynolds, Stanton and Damköhler numbers.
Scramjets are not the ideal engine for missiles. Amongst other things, the whole front of the engine is required for the air intake, which doesn't leave much room for a guidance package. The next is that the nose of the missile itself would be hot, complicating any heat seeking guidance. the last is a practical issue. Solid rockets are incredibly reliable, and it would take a lot to trade reliability for a possible increase in range.
Slashdot Mirror
" the best way to build a skyscraper is not to use CAD programs at all, but a slide rule and pen'n'paper, which force you to think about what you're doing instead of making mistakes and 'correcting them later'."
Except that using a CAD program forces yyou to draw to scale. I've seen a surprising number of hand drawings which have two bolts intersecting.
Using tools is supposed to prevent stupid mistakes, allowing you to concentrate on preventing smart mistakes. If your debugger doesn't fall into this category, then something needs to be fixed.
I hope this is not too picky, but both your examples of poor design are examples of the discovery of a previously unknown engineering phenomenon. In the case of the Tacoma narrows it's vortex shedding, and in the case of the Millineum bridge, a resonant evvect caused by people walking in step with the current vibration. It's rather like discovering that on the trillion-and-first iteration, your CPU explodes. It sucks, but it's not a case of poor planning.
Which systems, exactly? I work in a research institution, and we use both Suns and PCs, and every one of our benchmarks that I've seen show that, at any given time, a high end PC (Redhat) beats out a high end Sun (Solaris) workstation for the 3 main CFD codes we use (CPU intensive tasks).
We still buy Sun, for ease of administration, reliability and warranty, but not for speed (or speed/cost ratio).
What the ancient Greeks called democracy, and what we call democracy are two different beasts. It's all in what you define as a citizen. In ancient Greece, you could vote so long as you were male, greek, and rich. That sounds more like an aristocracy than a democracy to me.
Your assumption that all democracies are equal is ill-founded.
In the mean time, you've just lost at least one sale per broken link. Perhaps they don't think that's acceptable?
One of the major strategies to get any complex project to work is to use off the shelf parts. For physical engineering, those parts are defined by standards, and their properties are well known _and_documented_. For instance if I want an M10*1.5 socket head cap screw of strength rating 8.8, the properties of that piece are very well documented.
The problem with software engineering is roughly the same as if you made a bridge with every bolt individually hand made. It's a quality control problem.
Physical engineering generally does the same thing as code building, use standard parts to build a variation on a theme. Creativity in the selection of standard parts will end up in an end product of unknown quality.
It's not that creativity doesn't play a role, more that it shouldn't play as much of a role if quality product is to be made.
Generally the waste product of burning H20 and air at high temperature also include OH, NO, NO2, CO, H202, HCN, and about every other combination of O, H, N and C, your imagination can supply. The quantities of these other factors are dependant on temperature and pressure, so the amounts of these other things should be small in a fuel cell, so long as temperatures are kept down.
Here's an interesting piece of math.
Take the worst case:
You have 32 pieces, therefore, at each move there are 32 factorial board arrangements.
=2.6e35 positions
Assume 50 moves
=1.32e37 positions
How do you get out of this more moves than molecules in the universe?
Which is not to say that there are not problems with the current peer review system. The current pressure to publish, means that the requirement that the published results should be original can get softened. The outcome is then more papers, with the same amount of scientific work.
If Schön was putting out 30 essentially similar papers per year, then the peer review process may have been failing to ensure that each paper had sufficient new material to warrant publication.
On a lighter note, I've always found that this pretty much summarises my idea of experimental physics.
The answer to any question,
"Why wouldn't a custom *** be cheaper than a kludged job?"
is: The rule of thumb is custom jobs cost 10-100 times per unit what a mass production product costs. Do you think they can make walkmans for 1/10 to 1/100 of the current prices?
In addition, even if you assume 2e44 possible positions (64!-40!)*50 moves, you've still got storage which weighs less than the earth.
Here's an interesting piece of math.
5.26e36 bits
assume each bit can be represented in 5 atoms of silicon.
5 moles of silicon=3.01e24 bits=0.14 kg
5.26e36 bits= 2e11 kg
The mass of the earth is 6e24kg, so you're much smaller than the earth.
Since the density of silicon is 2330 kg/m^3, this mass is 1e8 m^3, or a cube of silicon 472m on a side.
Math=1
Intuition=0
The trouble is, that the niche between laptop and desktop is not really addressed. A lot of people (me too), would like a protable system, but do not need mobile computing. We're therefore reluctant to shell out big bucks, and sacrifice performance for a property we don't need.
Say I have a screen and keyboard in the office, and at home. I could pay â2500 for a top-end laptop with limited performance, or â1500 for a portable which screams. The problem, however is that the portable is not available.....yet.
How appropriate for this topic.
I tried to find another comment to pirate, but all I could fine were some comments with the first five words repeared over and over.
Or with a science degree you'd know that as energy goes with the square of velocity, that the car is producing 9 times the energy (ignoring drag), and I doubt if it has a very different mass to the original, so the batteries have 9 times the energy densities of the old cells. Take your pick as to whether this is 18 or 81 times better than the original.
This is why scientists only trust liberal arts students to do simple maths like adding up McDonalds orders, or balancing the budget.
As an Australian (briefly overseas) I'd have to say that the fact that I don't know anyone with a minidisc player, and have only rarely seen portable players being used, that the format is not popular there. Maybe I just know too many people with CD burners.
Mach 4 at 1 bar doesn't have the same heat load as Mach 7 at 0.02 bar. And you need to be going faster than your cruising speed anyway if you want to launch from a rail gun.
That is really the core of the problem. If its a missile, the engine can be sacrificed, so it doesn't really need to slow down at its destination, but a non-ballistic missile does need guidance, which is a challenge. The idea is that it would be superior to a rocket because it would be only 35% of the takeoff weight for the same payload. Launching civilian payloads to space is probably the best goal. It's not like the world desparately needs more methods of raining down destruction.
No, actually you can work it out. The speed of sound in a gas in meters per second is equal to sqrt(ratio_of_specific_heats*8.314*Temperature/mas s_of_one_mole_in_kg)
The only pressure dependance is a very small one, through the ratio of specific heats. Basically the speed of sound in a gas is independant of pressure and density.
This is true in a closed system, without heat addition. This is not the atmosphere. In the atmosphere the Pressure dropps off logarithmically, but the temperature makes a kind of sinusoid.
Maybe... Say a missile is cruising at Mach 8, and Altitude 35km. The weak Mach angle is then 7 degrees, meaning that the missile would have gone 280km past the sensor before it was detected, now extend that to Mach 20 and 50km altitude, and you're up to 1000 km past the sensor.
Opinions vary. Estimates of starting Mach numbers range between Mach 4 and Mach 6.
If the fuel burned, of course thrust was achieved. However, to answer your real question, this engine was not designed to produce net thrust. It was designed to achieve supersonic combustion within the simplest possible configuration
Actually for Hyshot, the design temperature was 220 Kelvin. A weather balloon was sent up beforehand, to make sure that the air wasn't so cold as to suppress combustion.
The Mach number is a similarity parameter. That is, all craft travelling at Mach 7.6 experience similar problems, regardless of the actual speed. Other similarity parameters include the Prandtl, Reynolds, Stanton and Damköhler numbers.
Scramjets are not the ideal engine for missiles. Amongst other things, the whole front of the engine is required for the air intake, which doesn't leave much room for a guidance package. The next is that the nose of the missile itself would be hot, complicating any heat seeking guidance. the last is a practical issue. Solid rockets are incredibly reliable, and it would take a lot to trade reliability for a possible increase in range.