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  1. GregLocock

    Friedel's Model (two-phase) and Noise Attenuation Questions

    I'm /guessing/ that the 120 dB at 2m is for a PSV venting to atmosphere. Compared with say an IC engine that is pretty small beer, so you should be OK with truck type exhaust pipe. To get around the organ pipe effect you could add a Helmholtz resonator, or an expansion/contraction muffler, which...
  2. GregLocock

    Cylinder design pressure for aftermarket 4 stroke cylinder.

    You may glean some handy numbers from https://www.eng-tips.com/threads/peak-cylinder-pressures.215499/
  3. GregLocock

    stresses in framed structures

    Superficially it looks similar because it is a regular truss with a point load, but in general there is little obvious similitude between a force diagram and the geometry of a structure. Here's an example Unless you know how to construct a force polygon at a joint I don't see how you can...
  4. GregLocock

    Roller Coaster Design Challenge

    waross- yes I agree in the absence of friction etc then the shape of the path (ignoring the loop) is irrelevant. Brachistocrone is optimising for minimum total transit time, not exit velocty explicitly. Personally I'd steal my grandson's Hotwheels and do some experiments rather than trying to...
  5. GregLocock

    stresses in framed structures

    Well, if you finally get around to doing it properly you should get something like this for the bar forces. I got the geometry by cursoring figure 8 Coord=[0 185 0;0 0 0; 206 185 0;206 28 0;399 185 0;399 52 0;596 185 0]; % coordinates of nodes Con=[1 2; 2 3; 3 1; 4 2; 3 4;3 5; 4 5; 4 6; 6 5;5...
  6. GregLocock

    Friedel's Model (two-phase) and Noise Attenuation Questions

    " I assume the PSV discharging into a pipe would attentuate the noise for nearby operators, but don't have any experience to suggest what an actual attenuation value would be." A dangerous assumption. That depends on a host of factors, but you have basically created a steam powered organ pipe...
  7. GregLocock

    Roller Coaster Design Challenge

    So, ignoring aero drag, m*g*h=1/2*m*v^2+integral F dx, and we want to maximise v. F is the friction force. So there's a tradeoff between minimizing F (ie low radial accelerations) and total path length. So a big part of the problem is deciding on the optimal shape and size of the loop. A big...
  8. GregLocock

    stresses in framed structures

    The diagram is, AS THE ORIGINAL TEXT states, a superposition of all the joint diagrams, and I have explained how to construct it in one of my posts. I don't teach stupid.
  9. GregLocock

    Roller Coaster Design Challenge

    Th optimum loop may not be circular.
  10. GregLocock

    Axial load profile for a submerged pipe. How can this textbook be correct?

    "Is my reasoning correct here?: no as explained elsewhere. Forum shopping will not improve your understanding.
  11. GregLocock

    Electric "missile" type UAV/Drone

    I'm not entirely sure that designing rockets/drones for Pakistan is a great use of our time right now.
  12. GregLocock

    stresses in framed structures

    Eyeballing it the right hand triangle, b is roughly 2^.5*70, and a is roughly 70. Yes changing the dimensions will change the forces in the members.
  13. GregLocock

    Spain and Portugal power grid collapse

    Here's the Australian spec for grid forming rather than grid following inverters. https://aemo.com.au/-/media/files/initiatives/primary-frequency-response/2023/gfm-voluntary-spec.pdf?la=en&hash=F8D999025BBC565E86F3B0E19E40A08E
  14. GregLocock

    stresses in framed structures

    I'd be very wary of using a reference that labels a force diagram as a stress diagram. Anyway he's constructed a Cremona/Maxwell diagram . This is good. I'm not crazy about his notation, should have used Bow's. The key to determining the forces in a and b is shown in the little triangle at the...
  15. GregLocock

    Stacking an object

    Each book will have a torsional rigidity (about the axis into the screen in your picture). As you stack them up there is a compressive load due to the weight of the books, and at some point you will get Euler elastic buckling, which for self weight was first correctly solved in 1912. This is...
  16. GregLocock

    Electric "missile" type UAV/Drone

    Possibly, there again this will have the worst performance of any possible configuration except for flapping wings. People in the past have got into trouble for designing cruise missiles and the like (which is not very difficult if you are after minimum viable product performance), I think we...
  17. GregLocock

    Things are Starting to Heat Up - Part XIV

    In which dik either demonstrates a complete misunderstanding of %ages, or knows damn well what he is doing and uses them to mislead (a politer version of what I initially wrote). See post 132. The %age is dropping slightly, the coal use is increasing, as Tugboat said.
  18. GregLocock

    Seeking Guidance on Learning to Use ACOEM ONEPROD Vibration Analyzer

    B&K produce an excellent series of manuals and technical notes on signal analysis in general and vibration monitoring. The HP/Agilent intro is also fine...
  19. GregLocock

    Paths to 100% renewable power, globally

    True but does not support your easily disproved claim. Their coal consumption is increasing. 95% of the coal power stations being built are Chinese. Here's the graphs for China

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