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  1. Baluncore

    Simulate the temperature inside an aquarium tank

    Before posting convert all mass to kg, all temp to °C, and all volumes to litre or m3. Eliminate the confusion. Convert everything before or outside the procedure. You do not need °F, pounds or BTU in computations. Water weighs 1 kg per litre, so you do not need to differentiate between...
  2. Baluncore

    Rough surface of swift wings

    The primary reason for having feathers is thermal insulation while being exposed to airflow. Feathers also shed water, self repair by zipping back into place after a disturbance, and can grow topologically from a pore in the skin. The fact that birds can fly would be irrelevant if they did not...
  3. Baluncore

    Face width of a spur gear pair

    How have you come to that conclusion? Are the gears you surveyed made from metal or from plastic? When correctly lubricated, metal gears will NOT wear significantly. Higher speed spur gears will throw lubricant from the pinion. Is the lubrication by oil bath, or open and exposed, greased once...
  4. Baluncore

    Mechanical lifting device

    The thing that confuses me is the term "front" being used to refer to what I and the Royal Wolf document call the "side".
  5. Baluncore

    Classical Oscillations in Fluids

    It sounds like you are interested in gravity waves near the surface. https://en.wikipedia.org/wiki/Gravity_wave#Shallow_water
  6. Baluncore

    Mechanical lifting device

    I am confused by the poorly specified problem. Can you provide a 3D sketch of the deployed extension cover. Can the cover be detached completely from the container? Is the cover stored inside or outside the container when not deployed. What else is then also inside the container. A cover that...
  7. Baluncore

    Automotive Aerodynamic drag on a car and recovering some of that energy using a fan

    Even if it could work, what percentage of the time does a vehicle travel at or over 130 km/h ? Is it worth carrying weight and complexity when it is used for so little time? You have plenty of time to think about that next time you are driving up a hill, or sitting in a traffic jam.
  8. Baluncore

    Where is the demodulator in this AM receiver?

    https://www.eeweb.com/extreme-circuits/circuit-project-am-receiver
  9. Baluncore

    Where is the demodulator in this AM receiver?

    Not quite... The 500 pF variable capacitor is in parallel with a fixed 200 uH inductor. That parallel LC circuit is tuned to resonanate at the receive frequency. The inductor is probably also being used as the antenna. I believe the first two transistors form a low frequency darlington pair...
  10. Baluncore

    A DFT calculations for metal oxide semiconductors and graphene oxide

    Welcome to PF. Density Functional Theory (DFT), not Discrete Fourier Transform (DFT). https://en.wikipedia.org/wiki/Density_functional_theory There is a list of publications here; https://en.wikipedia.org/wiki/Density_functional_theory#Key_publications
  11. Baluncore

    How can I measure the terrestrial tide on my place?

    Can you please give a link to the tidal data on the internet. The Earth tide computed by the “Solid” software correlates remarkably well with the borehole data observed. "Solid" is used to reliably remove tidal changes from gravity surveys. For ocean tides, the coastal profile geometry...
  12. Baluncore

    AC superconductor transmission

    As current in a superconductor increases there are two limitations. The first is that there is a critical current density at which the superconductivity ceases. That is of the order of about 105 A/cm2. The second is that the current flowing when superconductivity is suddenly lost, can generate...
  13. Baluncore

    5G beamforming

    The simple rule of thumb is that the beamwidth of the main lobe will be 360°/ 2Pi = 57°, divided by the width (measured in wavelengths) of the antenna, or array of elements.
  14. Baluncore

    Is the Force on a Dam dependant on the height of the water or the amount of water?

    Place two different diameter vertical tubes next to each other. Join them at the bottom. Pour water into one tube and notice the water settles to the same level in the two tubes.
  15. Baluncore

    Building a three phase motor -- need help figuring out how many poles

    Resistance. √ ( R2 + XL2 ) When you have a resistor in series with the reactance of an inductor, the total impedance is the root of the sum of the squares, because reactance is at right angles to resistance, and the impedance is the length of the hypotenuse of that right angle triangle.
  16. Baluncore

    Building a three phase motor -- need help figuring out how many poles

    https://en.wikipedia.org/wiki/Three-phase_electric_power Or the math; https://en.wikipedia.org/wiki/Three-phase Line voltage, V, is measured between two of the phases. The current, I, is measured in one of the phases. 3PH Power = V * I * 1.732 So don't be surprised by a square root of three =...
  17. Baluncore

    Unplugged Chest Freezer and It Won't Freeze Anymore - Why?

    Did you keep it upright? To find the thermostat, follow the power cables to the pump.
  18. Baluncore

    Building a three phase motor -- need help figuring out how many poles

    Unless it is a synchronous or induction motor, when; Synchronous RPM = 120 * Frequency in Hz / Number of poles. Notice that the synchronous RPM is independent of the number of phases, or the voltage. The number of poles is always even because coils make magnetic poles in N-S pairs.
  19. Baluncore

    Ladder-like bandpass filter theoretical analysis problem

    Here are later versions of the files used for post #18
  20. Baluncore

    New Degree Costs In Australia

    Australian universities are funded by the Federal Government to educate Australian students. Those students make a co-payment, or borrow that from the Federal Government through the HECS or HELP scheme. https://en.wikipedia.org/wiki/Tertiary_education_fees_in_Australia A significant income was...
  21. Baluncore

    Building a three phase motor -- need help figuring out how many poles

    Poles = number of coils per phase, multiplied by two. The number of poles and supply frequency decides the synchronous speed.
  22. Baluncore

    Air surge tank calculations

    Engine inlet and exhaust tuning. Transmission line theory. Helmholtz resonators and organ pipes. Acoustic modelling techniques.
  23. Baluncore

    Need to use a rectifier... but where to put it?

    The “Variac” is an autotransformer, it is not an isolation transformer. https://en.wikipedia.org/wiki/Autotransformer Notice that a Variac offers no electrical isolation.
  24. Baluncore

    Need to use a rectifier... but where to put it?

    That is a very dangerous circuit because it is connected directly to the mains Active and Neutral, without any isolation or fuse. If the Active is accidentally swapped with the Neutral, the chassis will become live. If the 3uF capacitor or the dimmer fails short, the current will no longer be...
  25. Baluncore

    RLC-circuits where phasor diagrams don't work

    For any one frequency, series and parallel RLC circuits can always be resolved into a complex impedance. The phasor diagram gets more complex when the excitation is not a pure sinewave. That is because R,L & C can be measured and marked with frequency independent values, but the reactance of...
  26. Baluncore

    RLC-circuits where phasor diagrams don't work

    The relative magnitude and phase of voltages and currents in AC systems can be represented by vectors, or phasors on a phasor diagram. The combined impedance of RLC elements can be represented as a complex number, Z=(R+jX), which can be seen as a vector. The simplified examples used in...
  27. Baluncore

    Can this version of pneumatic piston sustain a certain load on its own?

    The piston will appear to be like a spring. As you move the piston the enclosed volume will change, because the area of the piston A1, is equal to the area of the annulus A2, plus the area of the rod. You have rediscovered the pneumatic equivalent to half of a regenerative hydraulic circuit.
  28. Baluncore

    Earth busbars

    Are you sure one of them is not a Neutral ? Do not connect Protective Earth and Neutral except at the one point in the switchboard.
  29. Baluncore

    Vacuum Tank Query (Aluminium, Carbon Fibre, etc, Composition)

    You have failed to identify the application of the vacuum tank, so the leakage rate and potential for contamination cannot be assessed. Why is the use of the vacuum confidential?
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