Phone with GPS and barometer - I want a Kalman filter

My personal elevation, and air pressure corrected for elevation both change rather slowly.

With a suitable Kalman filter, my phone should be able to use the barometer to cancel some of the GPS elevation noise. I don't know how much noise the barometer has, but it seems low, compared with pressure change when I walk up a hill.

Most important, I want the corrected elevation estimate used to compute my local sea level pressure.

The pressure curve doesn't tell much about the weather, when I suddenly walk home from the office.

Screenshot from Barometer Monitor.

USB memory stick where anyone can add files, but only I can read, modify or delete.

I.e. a stick where adding a file is equivalent to encrypting the file with my public key and mailing it to me.

PFD for Vacuum Flask

I want my thermos to float when I lose it from a kayak. So it needs a Personal Floating Device. Most likely solution is a neoprene cover. That would also reduce the noise when it's rolling around in an otherwise empty cargo compartment.

Kayak bottles

I want a bottle that will stay in place under the shock cords on a kayak's foredeck.

That most likely means one concave side to align with ridge running the length of the deck.

(And I want them both for cold and hot drinks.)

Bike helmet, safe for jungle gym use.

Sadly, some times kids are suffocated by their bike helmets while playing in jungle gyms. They shouldn't wear their helmets while climbing, but they will.

I can think of two approaches to making the helmets safer for climbing.

The first is shape. The helmets worn by trawler crews look like they are less likely to catch anything.



The second is the strap. Can someone please design a strap that will keep the helmet in place when jerked, yet releases when pulled by the kid's body weight for a couple of seconds?

Vertical monofin

Yes, I know human anatomy, like seals' and whales', is best suited to a monofin with horizontal flukes.

Still, trying to swim like a fish, with a vertical monofin/tail, would be an interesting workout.

The product is not totally utopian, I did find one on Youtube. But I don't know where to get my hands...uh, feet, in one.

First the fundamentals: A material with negative dimensions

It's obvious: A wall with negative thickness gives a house with Potteresque properties: Small on the outside, but big inside.