Spedley

I understand the biological necessity for Mental Effort as it stops you over stressing your body and burning more calories than needed but I don't understand how it works. Example, when you do excersize you get to a mental barrier at which point it becomes mentally difficult to continue exercising. You may just be using one arm with moderately elevated heart rate and breathing and yet it changes from a physical effort into a mental one. I don't know how the system works but I guess that a chemical signal in the brain depleats the longer it is used and mental effort affects the production of the chemical? Compounds like adrenaline adjust the takeup of the signals, not giving more strengtg but making it more easily available. It seems that a drug which affects this chemical would be highly addictive but also highly useful.

Thanks, I did consider that kind of setup originally but for other reasons. I'll try it.

That was a very good example of why cars won't be fully autonomous for a while yet. Assuming the car could do anything it was told, I find it hard to specify what to do in that situation. The car needs to be far more aware of it's situation, e.g. how many lanes there are, which lanes are safe etc. I think the first real use of fully autonomous cars will be a dedicated lane on motorways where cars travel fast and in convoy with only automated vehicles permitted, probably in communication with each other acting more like a train. There would be a significant speed/efficiency advantage, very safe travelling and a gain of public trust and acceptance.

I have a basic understanding of pressure and flow but nowhere near enough to find the answers I need. I have water flowing at a high rate through a pipe (80L/m) and I want to divert some of this through a heat exchanger (30 L/m) whilst keeping the total flow rate as high as possible. I've included a diagram of roughly what I hope will work but I'm not totally sure how to get rough calculations of the dimensions required. Currently I have a single pipe diameter and a valve between the input and output to the heat exchanger (C and E) to create a pressure differential but this slows the flow and is very sensitive to any slight adjustment. In the diagram below, my idea is that the water flows in through A and out through F. At B there will be a higher pressure (I think) than D causing water to flow through the heat exchanger G and H. My hope is that flow will not be significantly affected and there should be a more stable flow through the heat exchanger. Firstly, I'm not sure this will work? Secondly, I don't know how to calculate the sizes for B and D or if the return flow at E will affect the pressure drop or if the pipe needs widening again at E to cope with the increased flow. Basically, I know very little and thought someone here may be able to point me in the right direction. (Also, there is significant resistance through the heat exchanger - lots of narrow passages and turbulence) (I've included a picture of the current setup, ignore the hot pipes to the heat exchanger behind it - the letters are from elsewhere and do not correlate to this post )

I've always thought of Survival of the Fittest as a negative feedback system. It implies that the population is declining and that a single individual is responsible for the advancement of the gene pool - only the best survive. Today I was struck that the bigger driving force of evolution is expansion into new territory. Environmental boundaries, e.g. land/coastline, forrest/grass, plain/hills offer room for expansion aswell as a challenge for a species. Individuals with the best adaptations will congregate on the boundary where resources are more plentiful. Even small advantages will be shared through a healthy gene pool of similar individuals, multiplying the rate of evolution into the new niche. I suspect that major changes could be achieved within very few generations under such conditions and that this is the real driving force of evolution.