ME 322 Instrumentation Lecture 1 January 21, 2015 Professor Miles Greiner Course administration, Lab 1, Probability Distribution Function, Population and sample mean and standard deviation

Web Resouses Course Website: – MECH322Instrumentation/ MECH322Instrumentation/ – HW, Reading and Lab assignment and handouts – Lecture Topics, Resources and Notes Use WebCampus to – Find ME322 Student ID number Use this instead of name on homework so I can hand it back in class – Grades – Upload Labs

Syllabus aching/MECH322Instrumentation/Syllabus/Syl labus.pdf aching/MECH322Instrumentation/Syllabus/Syl labus.pdf Some extra credit assignments will be available (~4% of grade)

Labs Lab Section 7 (ME ) – Fr 2:30PM - 5:15PM, Only has 7 students – Please send me an if you would like to move to If you want to move into any other lab you must find someone to trade with, and both must me This week – Do not meet in PE 113 this week – Do Lab 1 Measure Area of UNR Quad on your own – 22Instrumentation/Labs/Lab%2001%20and%2002%20Quad %20Measurement%20and%20Analysis/Lab%201.htm 22Instrumentation/Labs/Lab%2001%20and%2002%20Quad %20Measurement%20and%20Analysis/Lab%201.htm

Lab 1: Measure UNR Quad Area How much money should a landscaper budget to cover the UNR Quad? 1 lbm of grass seed covers 200 ft 2 and costs $3.49. Upload raw results to the ME 322 course information section of WebCampus by noon tomorrow (survey closes at that time). Turn in paper handout in class on Friday

Lab 1: Measure UNR Quad Area How to quickly measure length of – Short Side, S – Long Side, L Measure stride length, F – One foot to the other, not back to the first foot – Do you think stride length F will be “correlated” with student height H? What does correlated mean? Count number of steps to cover S and L.

Stride Length, F Measure a calibration distance, D C – Measuring Tape – Quarter mile track (1320 ft) – other Count the number of strides 3 to 4 times. – Report your height (H) in decimal feet. Do you think F be correlated with H?

Determine S and L Walk around the quad 2 times. – 4 measures of N Si and N Li Estimate (guess) Uncertainty – – What is uncertainty? Estimate (guess) Certainty Level – i.e. 5%, 50%, 90%... – What is certainty level?

Calculate Area and its Uncertainty Area How would you calculate ? If A = 1,134, ± 40, ft 2 Then write A = 1,130,000 ± 40,000 ft 2 (why?)

Best Estimate and Uncertainty of Cost, C How much money should a landscaper charge for seed to avoid loosing money because he/she may need to buy extra seed to do the job (due to the error in estimating the area)? Should budget be C + mW C ? – What should m be?

Assignment Measure quad area Upload spreadsheet to WebCampus by Noon tomorrow Turn in paper handout on Friday. Both are graded This is the only required lab that will not be performed in PE113

Questions Will all 127 of you get the same cost? Would one person get the same cost if he/she repeated the measurement 127 times? If a measurement is repeated many times, would the distribution of the results exhibit a pattern? Center and spread How can we quantify those patterns

Cost Estimate Histogram Define bin size Notice outliers (Can they be rationally eliminated?) Would shape (center and spread) change if many more samples were acquired? – What is “many?” Cost Estimate [$]

Probability Distribution function Shape for very large sample size

Sample Size For example if we take 127 measurements. n = 127 (Sample size) n < N (Population size, can be infinite!) Population Mean (center)

Spread Population Standard Deviation Strongly affected by samples with large deviations (Large X i –  )

Estimate μ and σ

What causes different length measurements? A person’s stride length is not constant – This causes random variations of the measurement – The length determined by the same person will be different each time he/she makes the measurement The average stride length used during the measurement may be different from that determined during stride-length determination (calibration) – This causes consistent or systematic errors (the measurement will always be higher or lower than the true length) Blunders…