# Search results

1. ### Passive vibration suppression using piezoelectric elements?

I am looking at one idea to passive vibration supression that involves "a resistive shunt to a piezoelectric material" but I can not find a lot of info outside of papers that I would have to pay for. does anyone know and can explain some detail about this method?
2. ### Recommendation for hydroelectricity

Homework Statement I am trying to write a report that recommends hydro electric power as a future technology for Canada. I was looking for help in deciding what topics will make up the body of the report Homework Equations The Attempt at a Solution for example, Benefits of Hydroelectricity...
3. ### Bending moment diagrams

So the F_r component for example, it generates a moment about the xy plane because it has a moment arm to the xy plane? But doesn't it also have a moment arm to the yz plane?
4. ### Bending moment diagrams

can someone explain why this problem would involve two bending moment diagrams, one for the xy plane and another for the xz plane? Also, how are the reaction forces at B and C determined each time?
5. ### Euler formula for sine

ok, i got it now. thanks
6. ### Euler formula for sine

Basically, I want to know how you go from ## ae^{jwt}## + ## be^{-jwt}## to ##Asin(wt + \theta)##
7. ### Euler formula for sine

can someone explain how you go from (4.25) to (4.26) using Euler's formulas in the attachment?
8. ### Equation for underdamped harmonic motion

thanks, can you also explain the "However, if you assume the function x(t) is real, then they are related as A = B" bit
9. ### Equation for underdamped harmonic motion

I found an explanation for the equation of under damped harmonic motion, x(t) = C cos(wt) + D sin(wt), but I was wondering if someone could further explain why: - "However, if you assume the function x(t) is real, then they are related as A = B - why is (A-B) is imaginary
10. ### Nyquist frequency and sampling frequency

Homework Statement ##N= \frac{2 f_s}{f_{lowest}}## ##\frac{f_s}{2} - \frac{f_s}{N}## Homework Equations - The Attempt at a Solution I have these equations listed on a formula sheet but I do not know what they are used for. It is from a chapter titled "Discrete Sampling and Analysis of Time...
11. ### Equal friction method for duct sizing

Homework Statement In the attachment. Homework Equations Chart of pressure loss due to friction for steel ducts : http://postimg.org/image/4iml9x761/ The Attempt at a Solution I don't understand the deltaP/L column of the results table. Where did the values come from? Shouldn't they all be...
12. ### Simple circuit question

Homework Statement Can someone why the voltage ##V^-## is the same voltage as that of R2? https://www.physicsforums.com/attachments/circuit-png.92144/ [Broken] Homework Equations - The Attempt at a Solution is it an application of KVL concerning the voltage for R1 and ##V^-##
13. ### Resistance Temperature Detectors

Can someone explain three wire and four wire RTD circuits in terms of how the lead resistances affect the voltage output ##V_o = \frac{R_3 V_s}{R_2 + R_3} - \frac{R_4 V_s}{R_1 + R_4}## Also, in the case of a three wire, what is the purpose of Lead C?
14. ### Pressure control

Homework Statement I have a lab on pressure control but I don't really understand the setup. I was wondering if someone could tell me what topics,chapters I need to read/look over to understand the network of valves on pg2. Homework Equations - The Attempt at a Solution -
15. ### Using calibration data for a beam scale -- How to apply?

Homework Statement I attached the full document, buy I just want to know about : "Using calibration procedure determine: a) Sensitivity (mV/gr) b) Overall instrument error (gr) c) Linearity error %FSO d) Hysteresis error %FSO e) Precision error %FSO" Homework Equations The Attempt at a...
16. ### Discriminator control

thanks very much for the reply! I have another question http://postimg.org/image/quz6smejb/full/ I don't really understand the basic conditions involving design/minimum volumetric flow rates to calculate reheat or to change the damper position. I was wondering if you could explain
17. ### Discriminator control

Homework Statement A factory has two zones. Zone 1 and 2 are both maintained at 75FDB. The design supply air flow rates to Zone 1 and 2 are 320 and 200 CFM, respectively. At a certain hour in summer, the cooling loads for Zone 1 and 2 are 6,000 Btu/hr and 3,000 Btu/hr, respectively. Assume...
18. ### Uncertainties question

Homework Statement A nominally linear electrical output force measuring device has the following manufacturer specifications: Input range : 0-100 lbf Full Scale output : 30mV Temperature effect on: Zero 0.002 % full scale/degrees Fahrenheit Span 0.002 % of reading/degrees Fahrenheit The...