KipIngram

Today I learned about the "read disturb" phenomenon associated with NAND flash storage devices. https://www.flashmemorysummit.com/English/Collaterals/Proceedings/2015/20150812_FE22_Tressler.pdf It was interesting to see Tressler's name pop up - he's a colleague of mine. I haven't worked "strongly" with him, but I've been in meetings with him from time to time.

About the Milankovitch cycle and the relationship between orbital elements to ice age / interglacial cycles. Fascinating stuff.

"Yellow Rose of Texas," via a YouTube of the diner fight scene in Giant. https://www.youtube.com/watch?v=e4ptm6F2KHQ

Yes, the point I was trying to make is that you have to engineer the system to deal with it (rigidly support the two counter-rotating wheels), and said engineering adds extra weight, cost, and so on. You're right - it shouldn't wear out your tires; the gyro effects would be "contained" by the supporting structure. Another thing you have to keep in mind is what's going to happen if a flywheel fails; those tend to be rather violent events. So you'd also need a containment system, and that adds weight and cost as well. But of course all of these technologies have risks (gasoline can explode too).

They would if they are turning in the same direction. But if they are turning in opposite directions you won't feel that resistance (if they're turning at the same speed and have the same mass distribution). You're right that there's resistance to either direction of turn. But there's still a cancellation effect when the flywheels are counter-rotating. I'd probably have to go to a reference to express it mathematically, though.

Actually if they are counter-rotating at the same speed then the gyro torques cancel "externally." Whatever structure is holding them in a parallel configuration will experience stresses, though, so that would have to be a strong enough design hence weight etc. I actually "experienced" this recently - my wife bought my daughter a couple of those little spinner thingies people use to just play with or spend nervous energy. I could hold one between my thumb and finger, spin it, and feel the gyro torques. But if I held two and spun them opposite directions (matching speed as best I could) that effect was much diminished. These gizmos: http://www.asseenontvandbeyond.com/Fidget-Spinner--The-Original-Stress-Relief-Toy_p_357.html?gclid=CjwKCAjwjPXIBRBhEiwAz-kF6Q65lc10fWJHVOZ-sQcSuW9mDPS7nKAosobLxjXtjiZo03OVvIYCPxoCI_gQAvD_BwE

Oh, well, when you spin your flywheel a stress distribution arises in the material due to the outward force caused by the rotation. So you also get strain per the stress/strain relationship of the material. That's basically a stretching of the chemical bonds in the material's crystal lattice. If you spin the flywheel too fast you exceed the yield strength of the material and it flies apart. That's all I meant. All that stuff boils down to something going on at the atomic / molecular level.

Hmmm. I haven't done any flywheel calculations in a long time. Flywheels don't actually store energy by stretching bonds; the bond-stretching is a by-product of the stress created by the rotational motion. The first order storage is purely kinetic. But the bond strength would of course be one of the limiting factors. I still think it will be hard to compete with a storage technology based on completely forming and breaking bonds as the primary mechanism, but I guess we'll see way or the other. The market will pick a winner from whatever contenders appear. I guess the next year or two will tell us a lot more about the viability of the glass batteries. The outfit I worked with at UT was heavily into flywheel storage - the flywheel being the rotor of a pulse mode generator. Our main research was in using such things (which we designed in-house), spun up slowly with a hydraulic motor and then discharged over a very short period, to generate electrical pulses used to fire railguns. The main competition was Maxwell Labs, who focused on capacitor-based technology for the most part. This all ancient history, though; going on 30 years. At the time the military was really interested in deploying railguns on tanks. In the end they gave it up, though. Gunpowder was just too good at the job. I'm hitting the sack for the night - catch you again later. Maybe before I sleep I'll put in a pre-order for my very own De Beers flywheel.

Well, fuel cells still use fuel; it's not an all-electric technology that could use electricity sourced by nuclear power. I think we've talked in another thread about capacitors vs. chemical energy storage. Humans have accomplished too many amazing things for me to say "never" very easily, but pure electric energy storage has a tough challenge to compete with chemical storage. I believe the point I made in the other forum was that the former stores energy via fields without breaking / forming chemical bonds, whereas the latter does have access to the full energy of those bonds. Like I said, I won't say never, but I have severe doubts. I'm not fixated on any one thing - "whatever gets us there" is great in my book. I just think that if the team at UT can make battery capabilities such as the ones mentioned in the article commercially realizable, then it could make a real difference. Electric already has a lot of advantages over internal combustion (not the least of which is efficiency). Safer, more economically competitive, and safer batteries could put them on the inside track. Can you recharge a fuel cell? By that I mean by inputting electrical power, as opposed to adding fresh fuel. If so, how fast is that process?

One of the things I love most about the modern era we live in is the resources it makes available for self-education. I think it's a wonderful thing. Also, I don't want to be perceived as taking the recent battery announcement as a slam dunk done deal. It absolutely could fail to prove out. But one can certainly hope otherwise; maybe this will be one of the rounds we win. It would certainly be a good thing for the planet. I've never been very enthusiastic about electric vehicles. It's cool technology, and I was loosely connected with a couple of EV programs while I worked at UT Austin. But I've always felt that the battery technology available was limiting. What people (many, at least; perhaps not all) is a vehicle they can take a road trip in. That means being able to hold several hundred miles worth of energy, which batteries are at least in the ballpark for. But it also means being able to stop at a service station and re-fuel in a period of minutes, which batteries have not offered previously. If this announcement lives up to the stated potential it could change that. Energy storage and conversion is a fascinating field; I very much enjoyed working in that area. I found it necessary to move to move from Austin to Houston for personal reasons, though, and the job market at the time took me back into digital electronics. Which can also be very fun, but I sometimes think that the 1990's was the high water mark for people with my particular skill set. I think the most interesting things going on in electronics today are at the VLSI level. I still remember the UT work with enormous fondness.

I'm an electrical engineer by training, but I don't claim familiarity with battery chemistries. I do have a good understanding of EM field theory and so forth, though. Within EE I'd say my specialties are digital electronics / computer architecture and also electromechanical energy conversion. What's yours? My undergraduate training and the largest part of my career relate to the digital electronics area. My PhD research and the smaller part of my career relate to the electromechanical conversion area.

Well, they mentioned that they can be charged much faster than Li-ion batteries. It's hard to see why power would go faster one way but slower the other way. I'm definitely not an expert, though.

Hey, UT Austin! My alma mater! Matt Patterson: Goodenough has a solid reputation, so I'd be shocked if it's a "hoax" in the deliberate sense. Hopefully further work won't be disappointing. That article Strange linked directly addresses all of the areas where we need breakthroughs: energy density, lifetime cycle count, charging time, and SAFETY. If it works out it will change the game completely.

"Adequately" means unambiguously. The amount of information required for the specification is the amount that lets you reconstruct the system as precisely as it is possible to do. Like Mordred alluded, some systems could have many, many degrees of freedom and yet still be "simple" if those degrees of freedom can all be specified with a small amount of information.

Off the cuff I would say that a system that requires more information to specify is more complex than one that requires less. So perhaps complexity <--> information content?