10-04-12 (Wed.) MECH 261/262 Measurements & Statistics **************************************************** Topics for final exam (10-04-29, AM) 261=2hrs., 262=3hrs. 1. Units conversion, e.g., mpg -vs- L/100km, but maybe something else. 2. Calibration and linear fit, i.e., straight line through data with minimum sum of least squares y-deviation 3. Instrument system and terms; that picture of the thermometer as an example. 4. Ohm's and Kirchhoff's laws a) "Perfect" bridge circuit b) Current/voltage source (output) impedance Rs->0 c) Instrument/sensor (input) impedance Rm->oo d) Up/down sensing resistors Ri in bridge for maximum sensitivity and (partial) temperature compensation e. Simple voltage divider/potentiometer for bridge zero-offset compensation. 5. RMS voltage; 3 question types a) Given wave-form specification, find RMS voltage b) Given wave-form shape and RMS voltage, find peak-to-peak voltage c) Given one wave-form specification and another wave-form shape, find peak-to-peak voltage of second one so as to produce the same RMS voltage. 6. Conversions among binary, deciaml, octal and hexadecimal bases a) Add and subtract, 2s complement, 10s complement arithmetic b) Analytic -vs- non-analytic codes. Gray (cyclic) code conversion to and from straight binary with XOR logic gate "iterative block" A | B || C=A(XOR)B __________ 0 | 0 || 0 0 | 1 || 1 1 | 0 || 1 1 | 1 || 0 7. Voltage divider using op-amp with binary fractional serial feedback resistor chain; making an ADC with a DAC and a binary voltage comparator 8. All about Op Amps, filters, etc. Bode plots, corner frequency, roll off, computing low pass, high pass, band pass and notch (band block) 1st order Butterworth filters. 9. Strain gauge basics and definitions, stress, strain, Young's and shear moduli, Poisson's ratio. Basic "steel block" force transducer, gauge factor, computing bridge output estimates for 1, 2 and 4 arm bridges. The cantilever force/displacement transducer and it's 2 and 4-arm bridge configurations. 10. In statistics all we've done is binomial distribution problems with known mean or expected values like the A-bomb cancer example and then spent lots of time on fitting data to lines in the plane (2-ways) for calibration, fitting data to lines in the plane for sum of least squares normal distances (correlation), fitting planes to data in 3D and fitting circles to points in the plane. **************Topics after midterm********************************* 11. Strain gauge torque cell and angle transducer 12. Pressure measurement according to Ch. 9 up to & incl. 9.1.2 plus web posted material; diaphragm transducer. 13. Temperature measurement " " form 9.2 up to & incl. 9.2.4 14. Flow measurement according to Chl. 10 up to & incl. 10.1.2 plus web posted material 15. Statistics; Poisson and continuous distributions: normal, students "t" and Chi-squared. Some poker probabilities