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"On a bright, sunny day, the sun shines approximately 1,000 watts of energy per square meter of the planet's surface"

like this

And how exactly are you going to transport all this energy?
They are called fuel cells.

How does this work? Info here!

I know this is just a light joke, but this is a mistake that is oft repeated...

THX is *not* an audio format. Stereo, Dolby Digital, DTS, hell even MP3.. these are all audio stream formats.

THX is an equipment certification, that certifies a set of equipment meets certain quality standards. (For actual theatres, it goes beyond just the AV equipment and looks at the whole environment including seating, screen angles, etc)

If you're interested, here's an excellent article on it.

Go here

747s average about 0.2 miles per gallon for a reasonable-distance flight. When you figure in their larger passenger capacity, it costs significantly less fuel to transport a passenger in a 747 than it does to transport a passenger in even a fully-occupied SUV.

To burst your bubble a little more, diesel-powered trains are significantly more efficient than planes or cars. A representative example would be the aggregate fuel efficiency of Burlington Northern, a large freight railroad. 751.2 GTM (gross ton-miles per gallon) in 2003 for their entire fleet of trains. We'll stick with the previous poster's comparison to the Cadillac Escalade EXT. With a gross curb weight of 3175kg (3.5 standard tons) and highway fuel efficiency of 16 miles per gallon, the Escalade weighs in with a whopping 56.0 GTM.

So, freight trains are 13.41x as fuel-efficient as Escalades. Now that must be a surprise...

Thank you for the info. I found this explanation on the launch window and the reasons they mention do not seem to apply to geo satellites. Also the wikipedia mentions "For trips into Earth orbit most any [launch] time will do". I suspect that the launch window for geo launches has more to do with weather and/or coordination than with orbital mechanics.

Whomever distributes these 'boycott' emails, rather than appeal to consumers emotional 'tough guy ego', should possibly fill inboxes with more logical approaches (with explanations).

Here's a start, and something everyone might benefit from reading if they hadn't already known:

What speed should I drive to get maximum fuel efficiency?

It's a shame I have to feel unsafe driving the speed limit on the way to work in the morning, I don't drive the most aerodynamic vehicle and glady sacrifice the few extra minutes.

I think travel to mars could end poverty
... on mars
much like the Freedom Boat the cost of anyone living on mars when that eventuality occurs would be quite prohibative allowing only the richest to enter and ending homelessness.
Heck, given a couple of thousand years, earth could just be mars' lower east side

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

In the Declaration it does not say property. It states there are others, unmentioned. If property is among them, and property is passed though wills to others upon death, do you therefore think ownership of inventions should be passed on indefinitely if willed by its owner? Once the block and tackle, gears, and hydraulics are invented, is it fair to expect all future inventors to pay for using those in their designs? Using leverage appears so simple it obvious. Should all inventors who don't want to pay have to use levers, such as the inventor of the crane?

If property is not among them, and government exists to serve the people, I say the people are better served by the accumulation of knowledge, invention, and art for all to enjoy. You keep saying a life cannot be lived without a way to pay for it, and I agree. Creators should get compensation if others desire their work.

You keep talking about the State granting and revoking rights. The people created the State, run it, and shape it. So the people had the State grant rights and remove others. Why should property be inalienable? It may help pay for the cost of living. Couldn't society decide we all work on kibbutzim growing and machining things to pay for living, but all invention and art are free for all?

If you remember an applicable Journal(s), I'd read that.

• Near total silence - 0 dB
• A whisper - 15 dB
• Normal conversation - 60 dB
• A lawnmower - 90 dB
• A car horn - 110 dB
• A rock concert or a jet engine - 120 dB
• A gunshot or firecracker - 140 dB

As the article demonstrates, any time you can get a battery, capacitor, and some wire together, you have the resouces to make a simplistic taser.

Yeah, a 1.5v taser that'll do a whole lotta damage.

The discharge from one of these capacitors is harmful because it's coming from 300 volts. There's pretty complicated circuitry in that camera that makes the 1.5 into 300 that charges the main capacitor. You're not going to find 300 volt caps in every piece of equipment. Why? They're expensive, and only necessary in high voltage applications.

Trust me, I've disassembled scores of these things, and been shocked by them. They're all around 350 volt caps. You know the whine you hear as the camera charges up? That's the 1.5 being stepped-up to 300.

The article says some cameras have 600 volt caps... I've never found one in a disposable. Those are for studio speed lights that are run from the wall power, with a voltage tripler circuit.

Read on, people.

Normally you would galvanise or paint it in with something water proof, but surly painting it would cover all the hooks up? I know this isn't an issue for stainless steel but there are plenty of other metals.

You can carry more information at 2.4Ghz though. Think of it this way if you use each peak to carry one bit of information then the frequency of peaks affects the data rate.

900 MHz = 900 M bps 2.4 GHz = 2400 M bps

To see how different encoding system work AM, FM PCM look here

"There are no rules in war, period".

Err, there are, here's a little primer The rules of war

Try reading this then. I play golf occasionally, and when it's obvious that the dimples do something. If you're ever hit a good shot off the tee you'll notice that the ball trajectory isn't parabolic, it curves up before coming back down.

There are two major hybrid techs out there, the honda and the toyota types (I believe that ford's is like the toyota one, dodge's was... bad and was dropped). The 2004 toyta uses a planetary gear that hooks up the gas engine and the generator together and also to the drive train, where the electric motor hooks up to it. This all acts like a CVT and a Power Split Device (PSD) to split the gas engine's output to both the wheels and to the generator. The gas engine only needs to be on when extra power is needed (high speeds or climbing hills where it gets sent directly to the wheels via the PSD) or when the batteries are low (power get sent to the generator) or a combination of the two. The electric motor does all the low speed low HP high torque work with the gas engine shutting down quite a bit of the time.

The honda ... well the honda has the gas engine as the main power and is always on (the newer civic does have a 'stop at light' mode but it rarely kicks in), the electric motor acts as supplementary to it and the whole thing goes through a normal transmission (which can be a CVT, but not the nifty PSD one that toyota uses, just a normal CVT).

The edmunds article on hybrids is misleading, check out the howstuffworks article for info on the prius

The NiMH batteries are much better on the environment than NiCD and Lead-Acid batteries. FWIW NiMHs are not considered hazardous waste by the EPA. There is some concern about the nickel in them (nothing concrete yet) but normal car batteries have lead (bad heavy metal) and sulfuric acid... not the best things in the world. I would be more worried by the lead acid battery in a normal car than the NiMH batteries on a hybrid. Of course they can both be and should be be recycled

Aluminum is a difficult metal to work. Welding to the body to perform a collision repair is going to be expensive because it requires equipment that most body shops don't have - TIG welder, stock of aluminum sheet metal, person capable of TIG welding without warping thin sheet metal. Therefore, the cars will be scrapped more often after collisions. Also, aluminum rots extremely quickly in road and sea salt conditions - look at city buses, there's a reason all of the panels are interchangable with only 1/2 hour and a rivet gun. More and more cars are using aluminum now, I know Audi's do so more shops will be able to deal with them.

Complexity - either real or perceived - of the drivetrain is increased. More and more people and shops will want to avoid working on them, which will drive up labor costs for service. Therefore, because they're expensive to fix, they'll get scrapped sooner.

Have you seen how the toyota hybrid works (not the honda)? It is incredible simple. It uses a planetary gear CVT/Power Split which simplifies the transmission. No torque converter or clutch and no complicated multi-speed gear boxes. Pretty nifty. Other things like generators (alternators) and electric motors (starters) already have equivalents in normal cars.

Late-Life vehicles - Will driving this car be at all practical if the assist battery is disconnected? When the car is 6-8 years old and being driven around by its last owner and the battery dies, will it still be usable as a conventional car, or will it be scrapped rather than spending the many thousands of dollars a new battery will cost?

Good question, but keep in mind that most of the old cars currently are the ones that are responsible most of the pollution, as time goes on we get new cars that run cleaner and more efficient. We also need to ask what portion of cars that are made now will be used in 6-8 years? Normal cars can need expensive repairs (new transmissions, new clutches) too and how many get junked for that? I know you keep really good care of your older car but I would have to say that is (regrettably) not what most people do.

1970 Dodge Dart 4-door sedan, mostly stock, seats 5 full-size (6 foot +) adults in comfort, modern radial tires, Slant-6 brings the thing up to highway speed quicker than most new econoboxes. And it's made of thick, solid steel. 34 years old, gets 25MPG highway, about 22MPG city.

How well will that car protect you in an accident? I know - 'it's made of thick, solid steel' - but we know all that means is that the shock and force of the impact will be directly passed on to the occupants rather than being absorbed by the crumple zones. This mean more and worse injuries to the occupants (see article). In 1970 there were 4.7 deaths per 100 million highway miles traveled, in 1999 there were 1.5. That is a nice improvement. Unless you added a catalytic converter to your 1970 car (they were introduced in '75), your Dodge Dart pollutes a lot more carbon monoxide and unburned hydrocarbons than cars after it with similar milage. Milage is important, but by no means the only thing.

"The "ham" part of ham radio is really a shortcut way of saying just the first syllable of amateur radio." Maybe you didn't know???

The low tech verison of this has existed for some time. It is called an EPIRB. Here is one that is less than 8oz and $150.

Why do slashdotters assume every dumbass post is a legimate problem to solve and RFID/linux/OSS/your_pet_tech is the way to do it ?

An interesting explanation about lightning can be found here.

According to the Mastercard site, the RFID tags will carry exactly the same information as the magnetic strip. And while these cards may indeed return encrypted information, there is no challenge/response system. That's just not how they work. When you broadcast the correct radio frequency close enough to these tags, they just resonate and play back (over radio waves) a predetermined string, encrypted or not. If you have a matching reader at your disposal, you have the means to read every RFID within range. Where would you get such a reader? Why, you could steal one, buy one at a distressed business auction, or open a small store and order one from Mastercard. Think of the RFID tag reader just like the magnetic stripe reader, but you don't have to do the "swipe."

Wow, does that override their applications in thermostats?

To clarify a little something for any non-physicists out there: Seat belts are designed to distribute force evenly across the strongest parts of a vehicle occupant's body (the hips and chest). We already have materials strong enough that 10 microns could restrain an accident victim, but a 10-micron seat belt would cut through your flesh, probably down to the bone in the case of an accident.

In other words, the world does not need a better 10 micron seat belt.

In California truckers are striking as we speak because of high diesel prices (well, because high diesel prices are undercutting their profits, they want a raise).

And as a final reason - the TOWING capacity of a Prius or Civic Hybrid, is something on the order of 600 pounds. I've pulled 2000 lbs in my Jetta TDI at 80 miles an hour. No problemo. Diesel=torque baby. Diesel=torque baby.

The electric motor on the Prius has 295 lb ft of torque at 1200 rpm, the VW TDI does 155 lb ft at 1900 rpm. Electric motors are great at torque, in fact diesel locomotives use diesel generators to run electric motors. Having said that I have not found the rated tow capacity for either the VW TDI or the Prius, as far as I can tell it seems neither one is rated for towing by their manufacturer. (the new mini-SUV hybrids are reported to have been rated at 1000 lbs towing)

getting rid of losses from the damn torque converter in the damn automatic transmission

I agree that hybrids are in their infancy but the prius doesn't use a toque converter/auto transmission, it uses a planetary gear power splitting device that acts like a CVT, pretty cool.

Honda and Ford are both leasing the CVT technology from Toyota. Since it's essentially just a gearbox, they have probably had trouble coming up with something that doesn't violate the patents on it.

its been around some time:
word spy
how stuff works

Yes, sadly no visionaries are left on the earth. This good idea here was never really realised because of money problems, only the giant hall is still standing: Cargolifter

The next big thing in fuel efficiency for conventional piston engines is the variable timing and lift technology now available in BMW's 4.5liter V8 and soon to come form other manufacturers. Fully variable timing and lift allow optimization of pumping losses across the rev range, as well as improved combustion efficiency for higher torque at equivalent RPM, at the price of potentially larger valve train mechanical losses.

Can't mention dynamic valve train management for air/fuel optimization without proper credit to the pioneer: Honda's VTEC.
Introduced way back in 1989 on the Integra in Japan and on the NSX in 1990 in the US. Elegant engineering genius.

hot dogs why not genetically engineered food.

Hmmm, there really isn't much to a driver. It's basically just a coil of wire attached to a suspended structure (the cone) that sits inside a permanent magnet. The energy is fed to the coil which makes it move inside the magnet which in turn moves the cone structure to create air pressure waves (sound).

Simple science-type experiments are super easy to do. No more complex than an electric motor experiment.

Although I haven't read it, this probably has everything you need.

If you can store potential energy in a spring (nano-springs?) Why not make use of this concept in modern cars much as hybrid cars do. Use braking to "wind-up" the spring, then energy from which can be used to give a good boost to acceleration.

Of course, the question is how much energy can we store in a spring and is it practical? Perhaps some research is required.

Thoughts?

If you can store potential energy in a spring (nano-springs?) Why not make use of this concept in modern cars much as hybrid cars do. Use braking to "wind-up" the spring, then energy from which can be used to give a good boost to acceleration.

Of course, the question is how much energy can we store in a spring and is it practical? Perhaps some research is required.

Thoughts?

Smart cards are similar to credit cards and serve the same purpose, but they have a completely different data storage system. Instead of using a magnetic strip to store the user's information, smart cards feature an embedded 8-bit microprocessor with up to 16 kilobytes of programmable-only memory. Smart cards have only recently began to gain popularity in the United States, despite their widespread use in Europe for years.

Domain Dynamics' new TESPAR voice authenticator stores three samples of the user's voice on a template within the Java-based smart card. When users want to make a transaction, they simply enter the card into a terminal at a store and give a speech sample. The card then matches the spoken voice to the recorded voice samples, a process that takes a fraction of the second. The company said that TESPAR is able to handle day-to-day variations in the user's voice and can ignore background noise.

Read more here.

... the image of the LCDs was brighter than the DLPs with similarly powerful bulbs (no, I don't know here the DLPs leave the 'extra' light :-). To achieve the same brightness, a DLP will require a brighter bulb ...

If you're wondering how a gyroscope works and what it does:

How stuff works has a nice article.

Nasa's also got a page about how they're used in space shuttles

Simple intro

Howstuffworks: I've noticed that I am not allowed to use my cell phone in airplanes or in hospitals. Why are these prohibitions in place?

ELECTROMAGNETIC INTERFERENCE

Electromagnetic Interference with Aircraft Systems: why worry?

those must be some mighty fine headlights, why not just equip the car with nightvision goggles, it would be cheaper.

I'm guessing this was a troll, but i'm going to pretend it isn't and answer it anyway.

The PSU, my misguided friend, is the Power Supply Unit. The "Power Supply" you referred to. I can assure you that you're using one, unless you have replaced it with a series of very large 12v and 5v batteries carefully wired into the rails.

Now, for the 8th-grade lesson you seem to have missed-- your power supply works using a large transformer to convert the voltage coming out of the wall into the 12v and 5v voltages required by your PC. How does a transformer work? at its simplest, it's a pair of coils of wire placed next to eachother. The coils are magnetically coupled-- the first coil gets the power from the wall and generates a HUGE magnetic field. The second coil does what coils do when placed in big magnetic fields-- it makes electrical current. The number of turns of wire on each coil determine the ratio of the input to output voltages.

That's how things worked in the 1980s. Now, today's power supplies aren't that simple. Computer power supplies today are switching power supplies, and use a frequency step-up before feeding into the transformers to reduce the size of the transformer needed. But you will note, as this nice article says and clearly shows in pictures, there are still multiple transformers in a switching power supply. And yes, the way they work is by shunting all the power you're using through a big ol' magnetic field between two coils with different numbers of turns of wire.

So, yes, your power supply is producing a gigantic magnetic field. One large enough to transfer all the hundreds of watts your PC needs through the air as a magnetic field.

If you find the earlier postings difficult to understand, Why not try How stuff works. It will give the answer in a simple, easy to understand answer.

Too bad city traffic is a lot more complicated than "Simple math"

While I won't be so bold as to say that speeding won't get you there any faster, I recognise the hidden costs.

First off, I should begin by referencing howstuffworks.com This article explains the concept of "the most efficient cruising speed" and even links to a chart dealing with gas mileage at a given speed. 50mph was more efficient than 60 or 40mph for every class of vehicle from sub compact to luxury vehicles.

Now to begin. There is a difference from the Ideal and the Real.
Ideally, for innercity traffic you have a stretch of roads with traffic lights all programed at a given speed. In my city its 40mph (even though sometimes the speed limit is lower or higher than this)

So lets say you've got two cars, CarF and CarS. CarF is traveling down Street Summperlane at a cruising 50mph while the other choses a more conservative speed of 40mph.
Again, Ideally, two things will happen. One: CarF will get to an intersection before the light turns green and will be required to stop. Two: CarS gets to the intersection just in time for a green light and can continue going at 40mph.

So now CarF must make up the ground lost while accelerating from 0mph to 50mph over carS, and this cycle will repeat for every intersection.

Analyzing the situation on a pure gas mileage basis, carS will get a better fuel economy even though he is not driving at his vehicles optimal mph, simply because he is not having to repeatedly accelerate from a stop.

And on a time basis, both cars are effectively throttled to 40mph by the traffic lights.

Now lets take a step back to reality. Posted speed limits in my city vary from 35 to 45, but the traffic light timings do not. You're basically encouraged to either speed or go below the speed limit, and psychologically going below the speed limit is unacceptable ;)

Of course, in my particular city I tend to get better results doing 50mph than I do going 40 in terms of Green to Red light ratios.

so, to reply to the previous poster, speeding = stupid. it saves no time, it uses more gas and causes significantly more wear to the vehicle causing higher maintaince costs. Ideally.
It does save time because we dont live in an Ideal world, you just gotta find the sweet spot. The gas consumption and Wear/tear on a vehicle will follow.

Long road trips are another matter though. You're better off on a car finance standpoint to go 50 the entire way. But seriously Who In Their Right Mind wants to make a 350mile road trip in 7 hours?
Anything more and you take a hit on your fuel economy, but its worth the time unless you speed excessively. Then there's the occasional Pass. It's pretty likely that you'll run into someone going slower than you are, so you'll probably downshift and accelerate hard to minimise the time spent passing said person. Especially if you have a limited passing lane ...

There are some exceptions to all of this though. The Hoover Dam is one of them. I've made the mistake of driving from Phoenix, Az to Las Vegas, NV during a week day. The Hoover Dam sucks! Any speed advantage you gained will be lost at this point because you're stuck going through the entire Hoover Dam in stop and go traffic and a maximum of 30mph. So what might have been an hour is now 5 minutes tops benefit. (and the only way around it is to go WAY around it -_-) So be smart about your speeding if you're going to speed at all. And realise that with many other things in life, there's a sweet spot, going beyond that will only be a hinderance.

Yeah, you're right, compared to the income for the at-the-pump tax, the SPR costs very little... How Stuff Works puts the cost at $21M for maintanance and $157M for buying oil (link) in what I think was 2000 or 2001. As for selling the oil high, it looks like they loan it to oil companies when things get tight and then ask for it back in the next couple of years... so I'm not sure how much of a profit that makes... but, its not unreasonable to think the SPR could be self-sufficient.

My point was more that the SPR isn't a very well targeted response to the problem, since it affects oil users and non-users equally.

You could say the same about anti-lock brakes. "What happens if the computer decides to release your brakes at the wrong time!!?".

Actually, YOU CAN'T say that about ABS, that's not how it works.

ABS will not engage without your foot pressing the brake. It's designed that way.

This system, however, is designed to engage on it's own. That's why it's 100% stupid.
One of the things people need to be able to do to keep control of their car is to be able to predict what it's going to do.

There is an absolutely HUGE difference between a system that is designed to assist a human and a system that is designed to do something totally on its own.

If they think the driver is asleep, they should kill the engine, roll down the windows and blast the radio (like a crescendo alarm clock, not suddenly).
While that might annoy the hell out of someone in the event of a false alarm, at least it wouldn't get them killed.

Altering the course of the vehicle is a very dangerous idea. It's about as bad as designing a gun to go off went it thinks it's being stolen so that the bullets can't be used in a crime later on.
If you could design the system PERFECTLY it might make sense, but the reality is that either system is a bad idea because even the slightest mistake could have disastrous consequences and mistakes are pretty much guaranteed.

All the lead is in the monitor glass.
The amount of lead in a base unit is limited to solder and tiny amounts within the ICs.

• Pedaling onto the Information Superhighway
  Laos villagers to get online with bike-powered PCs
• Could I power my computer or my TV with a bicycle generator?
• Pedal Powered Generator

Here is a photo of a Mazda rotary piston that was mentioned in the parent message. Here is a shot of the 8-shaped encasing.

Here is a photo of a Mazda rotary piston that was mentioned in the parent message. Here is a shot of the 8-shaped encasing.

Standard gear and rack interaction is well understood. Racks are usually straight-sided, while gear teeth are involute curves. Two gears which will mesh with the same straight-sided rack will mesh properly with each other. This fact reduces the size of simple gear inventories from O(N^2) to O(N).

"Mesh properly" has a specific meaning. There has to be contact on both sides of each gear tooth when the axes of the meshing gears are a constant distance apart. Getting this right improves gear life by orders of magnitude.

There's a nice little section in the back of every Boston Gear catalog which explains all this. Available online, too.

Nonstandard rack shapes are rare, but not unheard of. The drive system on the IBM RS-1 electrohydraulic gantry robot used a curved-sided rack.

How Magnetic RAM Will Work

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