Forgot your password?

Comment: Re:Charging amperage (Score 4, Informative) 395

Absolutely correct. Most electric cars (if you're keen, check out run at least 72V in a series string of at least 20 lithium-ion cells, and some run over 250V. Charging is done using a state-of-the-art high frequency AC/DC switching power supply with power factor correction, so that charging efficiency is maximized. For any given power transfer, double the voltage means half the amps, and that cuts the resistive power losses to 1/4, so it's always worthwhile to maximize the operating voltage within the bounds of the electronics (and safety considerations).

Comment: Re:Charging amperage (Score 1) 395

Most electric cars run at least one series string of cells so that each cell will see the same charging (and discharging) current. There are 'battery monitor systems' that monitor the terminal voltage of each cell so that you can detect if one cell is reaching its capacity limit in either direction... that's when you're done charging or driving. The trick with series strings is to know that the cells are at least nominally identical in capacity and internal impedance; then, to set them each to the same state (either zero state of charge or fully charged; and then to connect them all, and drive or charge until you hit the other limit on state of charge. If you work within the limits, you will be able to do series charging and discharge with no damage, and you'll get a long life out of the cells.

Comment: Re:This is good! (Score 1) 528

by TigerNut (#47771745) Attached to: Limiting the Teaching of the Scientific Process In Ohio

Maybe they're just not that smart....?



Perhaps they are behind where you were in terms of rote numeracy, but perhaps they have a deeper understanding of numerical objects than you did at that age?

I've spent pretty much my entire engineering career (25 years and counting) doing digital signal processing for realtime systems (voice coders, radio modulation and demodulation, GPS, inertial navigation, and graphics tomfoolery) and over time I've developed a pretty good grasp on numerical objects, algebra, and calculus, in fixed point, floating point, and modular field arithmetic. Certainly I know that stuff a lot better now than when I graduated, and I can think back through my schooling and see what was and what wasn't effective, from the basics through to a decently high level of applied math.

What I see my kids being taught, is basically a shotgun approach; but they spend so much time blasting them with alternate methods for doing things, that there is no time to teach the kids the underlying fundamentals which might help them tie things together; and the kids get confused between the different parts of the different methods so that instead of learning one or two methods fully and practicing it until they have it cold, they learn five methods superficially and forget the solution processes two days after the math unit ends.

Comment: Re:This is good! (Score 1) 528

by TigerNut (#47770411) Attached to: Limiting the Teaching of the Scientific Process In Ohio
My kids went through the same thing with the multiple methods of doing multiplication... holy sh!t did it frustrate the hell out of the younger one because once he had figured out a method that was intuitive to him, all the other methods were just, in his opinion, superfluous wastes of time. Now I hear that the "new thought" is that, for some things such as basic single digit multiplication, rote memorization is in fact the most effective method and it leaves time free to work on higher level problems.

FWIW, I did my grade school curriculum in the Netherlands in the 70's and it was like this (from a math perspective): Grade1: Addition/subtraction; Grade2: Multiplication tables. Lots of recitation to drive the numbers into your head. Grade 3: Long division. Grade 4: Fractions. Grade 5: Decimals and bigger numbers. Grade 6: Common factor elimination in fractional expressions.

My kids are three to four years behind that timeline because of the unnecessary fluffery that seems to pervade North American education.

Comment: Re:This is good! (Score 1) 528

by TigerNut (#47767309) Attached to: Limiting the Teaching of the Scientific Process In Ohio
Rote memorization is enough for math, hey? As others have already remarked, that will not work so well with division. Or algebra, or any other form of applied math. Or pure math. But I guess Ohio doesn't need to produce any math prodigies from here on. If you say "well, we can teach math methods so our kids don't have to be dumber than birds" then you have to teach logic (induction/deduction etc) so the kids can do proofs. Logical methods applied to everyday events (why do things fall?) begat the scientific method.

Comment: Re:Years ago, I was involved in an edit war. (Score 2) 219

by TigerNut (#45680627) Attached to: Wikipedia's Lamest Edit Wars
Having recently been involved in somewhat of an edit war (well, more of a "spirited discussion"... I'm in it for the long haul on behalf of my fellow Sunbeam Tiger owners), the "reliable citation" requirement is pretty much a nuclear handgrenade. Information is considered "reliable" if it's in a printed and published book by a "reliable source" which can be taken to mean "someone that writes a lot" - regardless of whether or not their writings are well researched in general or in particular. In our particular case, even appeals to demonstrable fact were treated with disdain because it was "original research" which is not permitted.

Comment: Re:That is the best use of text messaging (Score 1) 211

But they're not. SMS messages are sent over the control channel on the cellular network (which is why they use much less of the system infrastructure than a voice call, which requires assignment of a voice/data channel, etc.) and they can stay fully within the cellular phone system infrastructure. No email relays involved.

Comment: Re:Push the asteroid at the earth plz k thx bye (Score 1) 57

by TigerNut (#36099890) Attached to: NASA Satellite Snaps First Image of Target Asteroid
Ummm... orbital velocity is inversely proportional to its altitude above the earth. For LEO stuff, it's about 17,000 MPH (sorry about the units). If you want a faster velocity, you have to orbit lower, and then atmospheric drag would take it out within a few orbits. The moon's tangential velocity, relative to the earth, is only about 2700 km/h (or 1700 MPH).
The Internet

The Puzzle of Japanese Web Design 242

Posted by kdawson
from the how-to-pack-five-eggs dept.
I'm Not There (1956) writes "Jeffrey Zeldman brings up the interesting issue of the paradox between Japan's strong cultural preference for simplicity in design, contrasted with the complexity of Japanese websites. The post invites you to study several sites, each more crowded than the last. 'It is odd that in Japan, land of world-leading minimalism in the traditional arts and design, Web users and skilled Web design practitioners believe more is more.'"

Giant Planet Nine Times the Mass of Jupiter Found 73

Posted by Soulskill
from the fat-planets dept.
cremeglace writes "In the late 1990s, astronomers noticed a distinct warp in the disk of dust and gas orbiting a young star some 60 light-years from Earth. Now, using new analytical tools, researchers have discovered a giant planet lurking within the dusty haze. About nine times as massive as Jupiter and composed mainly of gas, the planet is only a few million years old, proving that such enormous planetary bodies can form rapidly." What's amazing about this is that the images taken of the star clearly show the planet first on one side of the star, and then the other, several years later.

Sticky Rice Is the Key To Super Strong Mortar 194

Posted by timothy
from the what-can't-sticky-rice-do? dept.
lilbridge writes "For over 1,500 years the Chinese have been using sticky rice as an ingredient in mortar, which has resulted in super strong buildings, many of which are still standing after hundreds of years. Scientists have been studying the sticky rice and lime mortar to unlock the secrets of its strength, and have just determined the secret ingredient that makes the mortar more stable and stronger. The scientists have also concluded that this mixture is the most appropriate for restoration of ancient and historic buildings, which means it is probably also appropriate for new construction as well."

Recession Cuts Operation That Uses Hair To Clean Up Oil 119 Screenshot-sm

Posted by samzenpus
from the hair-today-gone-tomorrow dept.
Matter of Trust, a nonprofit that uses human hair scraps to make mats to clean up oil spills, finds itself with 18,000 pounds of hair and nobody to process it. Lisa Gautier, who runs the organization, says that the recession has closed many of the textile makers that produced the mats and the warehouse that stored them. Unfortunately for Lisa the hair keeps piling up. From the article: "Hair is good at soaking up oil because, up close, the strands are shaped like a palm tree with scalelike cuticles. Drops of oil naturally cling inside those cuticles, says Blair Blacker, chief executive of the World Response Group. A pound of hair can pick up one quart of oil in a minute, and it can be wrung out and reused up to 100 times, Mrs. Gautier says."

Life. Don't talk to me about life. - Marvin the Paranoid Anroid