Posts by ilmari

Re: Handbrake users beware

Funny, I thought video conversion would be minimally hit, as it consists mostly of:

read(very many bytes); process (very long cpu intensive code); write(very many bytes)

Where, if the read and write are implemented as sending big requests to the kernel, should be minimally affected. The processing portion of it is surely 99% of the whole processing time anyway?

I could believe things like a database would slow down, when it's hopping all over the place on disk looking for/writing data. I could believe facebook slows down alot, because browsers are doing lots of itsy bitsy tiny reads and writes to both disk and net, and lots of small updates of the screen to animate all the gifs and what not.

Re: "To provide a better experience to customers"

What's preferable, phone unexpectedly shutting down without warning, or phone slowing down to avoid sudden shutdown?

The big issue is of course that the user wasn't notified in either case, on any brand of phone (androids also suffer from thus when their battery gets old, sudden shutdowns despite having 30% left).

On the other hand, it's not an easy problem to solve. Unexpected shutdown means unexpected, even if there was an algorithm trying to collect data about the operating state of the cpu and all its peripherals, and recording battery voltages, when unexpected shutdown hits you lose the data. The hardware shuts down to protect both the battery (since they become unstable from operating at low voltage) and the CPU, ram and storage from corrupting data due to insufficient voltage.

AMD have a "clock stretching" feature in some of their CPUs, if the voltage inside the CPU drops the frequency slows down. It's mostly meant to allow them to operate with lower voltages and save power by not needing as big "safety margin" in voltage. Would be interesting to see something similar in mobile SOCs!

It's kinda remarkable that battery meters are still so bad at tracking the capabilities of an aging battery. On one hand, it's a kinda neglected area where manufacturers choose the cheapest component. On the other hand, it's a difficult problem! Batteries aged in standard cycle testing behave differently to batteries aged in real life. Batteries in real life age differently depending on how they're used and charged.

What do I mean by aged differently? As is well known, a battery's voltage sags when you put a load on it. The bigger the load, the more the voltage drops. The amount of drop is, for most part, a linear function of the load. When the battery is new, the sag is so small it makes no difference. The amount of sag can be described as internal resistance. More internal resistance means more sag.

On a new battery, the internal resistance stays nearly constant regardless if the battery is 100% or 20% full. Towards empty it becomes a bit higher. With an ideally cycled and aged battery, the capacity is lower, and the internal resistance is higher, but the internal resistance is still around the same order of magnitude regardless the battery is full or empty.

With batteries aged in real life conditions, where the battery might've spent a lot of time at 100%, a lot of time at 0%, a lot of time in heat, etc, the results on internal resistance will be different. The internal resistance might sharply rise as the battery discharges. From the initial situation with a fresh battery having a flat internal resistance curve vs state of charge, to having a inclined straight line describing an increased resistance at empty, to having exponentially increasing resistance towards empty.

Why does this all matter? Because currently there's no battery meter chip that can take into account anything except the "internal resistance is the same regardless of how full battery is" situation. Most chips don't account for internal resistance at all.

So from an engineer's perspective, if Apple is actually tracking actual battery performance and managing to make their system adapt to having a smaller and smaller power budget, that's kinda impressive. Makes me glad someone is finally paying attention to adding more sophistication to battery management systems!

Of course, they could just have put in a battery twice as big and they wouldn't have had issues with shrinking power budget for the phone's "lifetime", and they wouldn't need to consider aging battery.

Re: Battery shape?

It's more like, the more you focus on a battery's ability to deliver high peak power, then more you take away from its ability to to store energy. It's a tradeoff. Mobile phones very much favour capacity over power, Apple perhaps more so than the rest. Also keeping in mind that Apple has very powerful CPU while at the same time having "unremarkable" battery capacity, in remarkably small space, it pushes everything to the limit.

In this case they pushed it perhaps too far, when some batteries have aged a bit too fast.

Re: $20 per transaction fee

I remember back in the day when some nerds were trying to explain the usefulness of bitcoin, they argued speed of transaction and cost of transactions as superior to regular banking. At the time I thought the argument was dubious at best, as bank transactions were on the order of minutes, and transactions usually included with other services anyway, costing nothing extra.

"But bitcoin isn't vulnerable to the whims of governments and central bankers!" - well sure, but is the whims of the collective speculative investor hivebrain any better?

I think the biggest issue is the sheer number of passwords required. The average person probably struggles to remember more than 2 "difficult" passwords. Add to that, that every little thing wants you to make a user account and password, so you end up with hundreds.

Re: Tesla semi?

The batteries should accept charge at the same rate as the stated acceleration, so 100 to 0 in 20 seconds. That seems like very aggressive braking under normal circumstances.

Likewise, if it can maintain a specific speed going up a hill, it can maintain the same speed going down the hill without the use of friction braking.

Laser altimeter is the kind of thing a hobbyist would use, since hobbyist radars make ofcom/FCC/etc annoyed. GPS and barometric sensors aren't that good for approaching the ground at a ensured survivable rate.

Re: planet is surrounded by spy satellites

I once found a submarine on Google Earth. It was just outside Tokyo bay. Always takes me awhile to find it again though.

Was out shopping for a new phone for my elderly father. At some point he had wandered off into the shop of the third largest operator.

When I informed the shopkeeper that yes, that's exactly the phone for him (a Doro), we can't really buy it since we do need to use the competing operator for coverage concerbs.

The shopkeeper cheerfully said he's happy to sell the phone even if we put competitor's SIM in it.

Re: Bah!

Now I understand why some 3D printers have SD card slot for storing the print while it's printing!

Re: Competing with their own customers

I wonder if it's google saying "If you guys won't do it right and be responsible about security and updates, then we'll just do it ourselves."

These tariffs are available elsewhere in Europe. Suppliers offer different "day-ahead market price + margin" tariffs, for example.

It works as long as a minority uses those tariffs, and as long as demand isn't too flexible (everyone choosing to use all their power at 3am to charge Tesla powerwall when it's cheapest).

Re: Not applicable in any place I lived...

There are battery powered electronic versions of that valve, including ones with wireless control through a central "router", and the facepalm quality mobile apps. I know one manufacturer already deprecated their first gen versions of this, leaving expensive systems vulnerable. I'm looking at you, Danfoss.

Re: Lithium batteries are last century's technology

There are phones with large batteries available. Hardly anyone buys them. Thus, battery capacity stays low on most other models. What's the point making phone with big battery when everyone is fine with 8hour life?

2 year life

According to the article, FP1 was still sold in 2015. It is now 2017, and the device is unsupported. If someone had bought it on a 2 year contract from an operator in late 2015, it might've entered unsupported status before the customer had even paid it off! Not to mention statutory warranty periods..

Why not? It works like autopilot on a ship or on an airplane, The only other autopilots I can come to think of.

Airplane autopilots will happily fly into other airplanes, with the collision alert sounds blaring, or halfway into a mountain before giving up the controls and telling pilot to do something in the last second.

Re: Wrong comparison

They already do, pretty much. Their sleep states would give around 2-4 weeks battery life, It's just that they power up constantly to check farcebook, twitters, instagrams, snapchats, whatsapps, Skype, telegram, google+, gmail, oemaccount, google play, weather widgets, location, etc...

Don't forget the last gpu cryptomining fad propped up AMD's sales for a year, drove up prices and killed availability.

I haven't been following very closely, last time only AMD GPUs were useful, are both brands useful this time around?

Re: Hmmm

There is no metallic lithium in Li-Ion batteries - normally.

It is possible to generate metallic lithium by overcharging. This makes the battery quite volatile for future use.

Another trick you can do is over discharge, which causes the copper to dissolve. On charging it back up again, the dissolved copper precipitates in random places, and may or may not cause a short. Slower version of Russian roulette.

Re: Petty?

It gets more complicated than that. I used to think suck per watt would be the thing to measure (and do you want to measure volume per time, or static pressure?)

With less suck, but with a rotating brush, you get surprisingly good results, and better results at removing dog hair than a traditional powerful suck.

On the other hand, that gives terrible results on getting sand out of a carpet. Except if it's a very smooth and non-porous mat.

So you'd probably want to include a range of different dirts on different surfaces, spread onto and into the surfaces using various methods, weigh before and after result, and consider energy and time used, and the amount of particles exhausted or thrown up into the air.

Maybe suck per watt would be easier.

I used to enjoy playing around with lossy media such as CDs tapes and usenet, throwing more and more parity at it, and sometimes deliberately abuse the media to introduce more losses, just to see how much could be wrecked and still have a human viewable picture or audio left...

With that said, it would be interesting to see what a modified CD drive would be able to pull from a disc cracked and carefully put together again. Modified, because you'd want it to ignore luxuries like adressing and error correction/reporting and just get a raw bits (or probabilities of a bit or no bit) back..

I imagine it would be impossible to get the tracks aligned again, so it would in best case be randomly jumping to different track and getting stuck like a grammphone skipping tracks...

I wonder how well the metal layer is bonded to the rest of the disc, if a crack and would severely distort it on the rest of the disc too.

Re: Fixed for pennies

Actually, from the article I get the impression that what the device had was exactly the above: A MOV.

The thing is, they get more and more sensitive over time, and WILL become fully conductive during normal voltage, eventually.

In a properly designed device you make sure that the resulting fire or explosion doesn't spread, and that there's a fuse that disconnects it when the short circuit does happen.

That's what the "Protection OK" light on a surge protector is for, once the MOV shorts and causes the fuse to blow, the light no longer gets power and goes out.

Re: The Reg

It took me 3 attempts to upvote this because of that same banner jumping text up and down. The posts after your post fit a few accidental up votes. Oops.

Often it loads covering the article headline and the first few rows of text, and stays like that for quite a bit. Sometimes I get to close it and click "ad covered content", but usually itnjimps to where it's supposed to be if I try to X it...

Re: Milking It

As someone working in a so far robot-free plant, situated next door to a fanuc shop, that was interesting news and I will certainly demand manuals if those fanucs try to get in.

If you know, what robot manufacturer UA the friendliest for maintenance technicians armed with a netbook, pieces of string and duct tape?

Re: Two things

One thing to keep in mind regarding ticking time bomb, the issue is said to be insufficient space for the battery to expand. As Samsung has been limiting the state of charge the battery can operate at, we can assume that the swelling is bigger either near full or near empty, or both.

So, what happens when you put what is essentially a balloon in a low pressure environment such as an aircraft cabin? Does it get bigger or smaller?

I think I finally understood why the note got banned on air travel.