Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

×

Comment: Re:Wow, an array of photovoltaic cells. (Score 1) 85

by jeffb (2.718) (#49479997) Attached to: Researchers Design a Self-Powered Digital Camera

What are you basing this assertion on? It sounds believable, but it also sounds like an unproven assumption.

I'm glad you asked.

1. I assert that it will always be more expensive to make an array of individual PV cells, with circuitry to route their output to readout logic and the global power pool, than to make a conventional sensor and a conventional PV cell with larger effective area. I can't "prove" this, but I can't imagine a realistic scenario where it wouldn't be true.

2. I observe that a sensor in an optical assembly, with light only entering through a lens, can only absorb light that falls on the lens. In fact, it can't absorb all of that; the lens will reflect or absorb some light and some won't land on the sensor, unless the sensor encompasses the entire FOV of the rear of the lens. So, if your lens has one square centimeter of aperture, and your light level is one milliwatt per square centimeter (pretty bright indoor lighting), you get less than a milliwatt onto the sensor.

3. I assert that any camera will have a housing with more surface area than its lens. That's where you put the (conventional) PV cell(s) to harvest energy.

Feel free to poke holes in these assertions and observations, or to point out things that they don't cover. I'll take a crack at it myself:

a. Maybe you've got a situation where most light is coming from a single direction, and your camera faces that direction. You build your camera as a cylinder, perhaps embedded into a wall, so that light falls on no part of it except the lens. In that situation, you don't have a place to put an exterior PV cell. I think this is an unrealistic scenario; if it's built into a wall, plug it in, or surround it with a PV bezel.

b. Maybe your manufacturing is so good and so mature that microelectronics cost a flat rate per square cm, whether you're making a simple PV cell, a simple CMOS image sensor, or an integrated light-harvesting imaging array. From what I know of semiconductor manufacturing, this seems unrealistic, too -- but even if we get there, you can still collect more light with an exterior PV cell (from points 2 and 3), as long as you aren't also in contrived scenario a.

c. You're in a mature IoT scenario, where you've got smart dust everywhere, and it all needs to be self-powered. Here again, though, those dust grains will have more surface area than the lenses integrated into them. In this scenario, I'd expect something more like a fly-eye arrangement anyhow.

Any other ideas?

Comment: Wow, an array of photovoltaic cells. (Score 1) 85

by jeffb (2.718) (#49479209) Attached to: Researchers Design a Self-Powered Digital Camera

I recently visited an old friend, and saw that he'd installed a PV grid on his roof -- three rows, with thirteen panels in each row, and separate control/monitor circuitry for each one. It took me about two minutes to say "you know, put up a big board with a hole in the middle, and you could do imaging with that array."

It was a dumb joke, not a profound engineering insight.

Yes, I'm sure this camera can self-power. No, there's no way to make it cheaper or more effective than putting bigger, dumb panels on the outside of the camera, outside the lens, where they'll collect light over a much larger solid angle. Heck, you'd probably do better by putting a semitransparent solar cell in front of the lens, and a conventional sensor behind.

Comment: Usability metrics, anyone? (Score 3, Interesting) 183

I haven't read the relevant regulations, and I hope I'll never have to -- I'm not sure I have that much time left on Earth -- but I'll bet that there's almost nothing concrete in them about usability.

EMR capture happens in a time- and attention-constrained environment. Any competent development house should be doing task analysis to ensure that their system meets the time constraints found during a doctor visit.

EMR search -- oh, I don't even want to start thinking about this. The relevant tasks could be anything from an auditor fine-toothed-combing records for an insurance claim, to an EMT trying to get a blood type or allergy info before a victim bleeds out.

I've consciously avoided jobs where my code is responsible for life-and-death decisions. The problem, I guess, is that too many other good people have made the same decision, and there aren't enough good people available to do what needs to be done. I'm not sure what to do about this.

Comment: Oh, I've got reservations, all right... (Score 1) 193

I've had reservations about the Apple watch since I first heard about it. My reservations, though, are the sort that will keep me out of the store.

All the same, I've been watching Apple and its customers long enough to know that I will be hanging on to my Apple stock. The watch doesn't have to make sense; it just has to make money.

Comment: Re:We desperately need unflashable firmwares (Score 1) 120

by jeffb (2.718) (#49308667) Attached to: Persistent BIOS Rootkit Implant To Debut At CanSecWest

Sure, that's a good point. Even if the Standard Update Magnet is a big, obvious device, you could make a Scamful Update Device that's a tiny but strong magnet designed to look like something innocuous leaning against the machine. But I still think it would be better than always-on reflashability.

Comment: Re:We desperately need unflashable firmwares (Score 1) 120

by jeffb (2.718) (#49292905) Attached to: Persistent BIOS Rootkit Implant To Debut At CanSecWest

If the attacker has physical access to your machine, you're pretty much hosed.

I suggest a magnetic switch because it doesn't affect the external profile of the device. Apparently everybody has decided that physical switches are ugly and horrible. Fine; hide it internally, but still make it require a physical action on the device, so remote attackers can't flip it.

Comment: Re:We desperately need unflashable firmwares (Score 4, Interesting) 120

by jeffb (2.718) (#49291305) Attached to: Persistent BIOS Rootkit Implant To Debut At CanSecWest

This. Even if you can't stand to mar your product's sleek lines with a ghastly physical switch, would it be that hard to put a reed switch somewhere along the periphery of the device, so that nobody can flash the firmware unless you first put the Big Honking Update Magnet next to it?

Comment: How's that again? (Score 2) 77

by jeffb (2.718) (#49282183) Attached to: NVIDIA To Install Computers In Cars To Teach Them How To Drive

I recognize that analyzing lots of data across lots of cars, drivers, and routes might yield useful knowledge. I'll bet there are even insights that no single human driver could ever gain.

But an awful lot of driving behavior comes from things that have nothing to do with anything this computer can monitor -- specifically, the driver's thought processes. If I slam on the brakes suddenly because I remember something I forgot at home, what will the computer make of that?/p?

Comment: Society to Preserve the Sacred Mysteries (Score 2) 172

"When a person buys an American quarter horse, they want to know that my quarter horse has the blood of these horses running through it, not copies of it."

Well, ick. Blood from horses that lived fifty or a hundred years ago must be getting seriously stinky by now.

In other news, this spokesman appears to be willfully ignorant of the most rudimentary concepts of biology. I guess "understanding" would ruin the nobility and romance of breeding...

Comment: Re:Sorry, it's a drug precursor. Not yours. (Score 1) 132

by jeffb (2.718) (#49253783) Attached to: New Molecular 3D Printer Can Create Billions of Compounds

Sure, but not at all easily. (Okay, iodine's easy if you can get hold of an iodide.) I've seen documentation of a homebrew project that successfully produced a small amount of phosphorus. It's definitely not a process I'd be willing to try, at least not in any building where I'm responsible for paying insurance.

If you think nobody cares if you're alive, try missing a couple of car payments. -- Earl Wilson

Working...