Recent content by inquisitivegeek

I've got to run but the CO2 concentrator consumes energy. Just from the title + the 2nd Law of Thermodynamics, one can deduce it: if you want to reduce the entropy you must invest energy into it.

I don't think it is worth doing either. CO2 is near the bottom of the chemical potential energy list - that's why you get so much energy from combusting C or CO.

The business model of companies like Wal-Mart is pretty conservative and does not take on large risk. Banks like Citibank - well let's not go there; the whole concept of fractional reserve banking is basically fraudulent. When the stakes become high enough that national interest/pride gets...

AlephZero's answer is the correct one. Carbon fiber has a high strength but lousy toughness, because it has practically no elongation after its ultimate tensile strength has been reached. Also because carbon fiber is so brittle, it must be encased in a rigid matrix material like epoxy resin...

All its merits aside, I think the difficulty with nuclear power, is that the cost of a disaster is not quantifiable and could sink any commercial venture that tries it and ends up with a Chernobyl. Even the biggest companies in the world - say Citibank, Wal-Mart or Microsoft - none of them...

Understood, but I thought the strength of the magnetic field from a magnetic dipole decays with a 1/r3 relationship, and linearly with the dipole moment. Most of the magnetic field lines would be paired with the corresponding magnet on either side of the hull for maximum torque transfer...

Yup, I read that, thanks. Very fascinating article. For the benefit of casual readers of this thread, the relevant section of bits flying off due to the compressed water is here: Is it possible to transmit sufficient torque to drive a submarine, magnetically through a paramagnetic or even...

Yeah, it would make sense, because any deviation from symmetry would start imposing weight penalties to reinforce against the added stress. It is a very unstable equilibrium though - relying on geometric symmetry to keep the pressure hull intact. Any deviation caused by say, an explosively...

Thanks for your reply. I understand the effect of hoop and longitudinal stresses on a cylinder. In the context of a submarine I presume the main danger from compressive hoop stresses is local buckling of any irregularities/stress concentrations on the hull and for longitudinal stresses the...

Hi everyone, It might seem like a silly question but given that 10m of water is about 1 atmosphere, the amount of hydrostatic pressure that deep diving military submarines undergo must present enormous waterproofing & engineering challenges. How is this problem solved? Using metals with large...

Hi all, Thanks for the replies. Regarding the little green dot artifact, it is still there if I try taking it from a different position; see second attached photo. The camera is an in-built camera on the laptop (driver is that of a USB camera). So, if I understand your explanations...

Hi all, I'm new to the forums. I recently tried to take an image of two laser dots on a white wall, using my laptop's USB camera. I saved them to PNGs. I have a number of questions... 1. There was an artifact with the green laser, where a smaller second dot appeared for some reason. What...