2381 Su14 Lecture 1 Introduction

MAE 2381

Experimental Methods and

Measurements

Introduction, Graphing, and Report Writing

Instructor

• Dibesh Joshi, Ph.D.

• Email: [email protected]

• Course Website: UTA Blackboard

• Office Hours: Monday 1:00 to 2:20 PM; Open door policy

or by appointment (via email) for other times

• Office: Woolf Hall 323J for office hours and appointments

Teaching Assistants

• GTAs: James Grisham ([email protected])

Siddartha Chintamani

Mariana Vallejo

– Will assist with questions about the labs

– Will assist with laboratory sections and grading of lab reports

– Office hours: TBD

GTAs for lecture: TBD

– Will assist with questions about the course and grade homework

assignments

• UGTAs: TBD

– Will assist with lab report grading

Class Format

• Lectures: Tuesday and Thursday 1:00–2:20 PM WH 311

– Discuss theory and practical issues related to experimental measurements

and professional reporting of results

– Bring notebook for example problems not repeated on Blackboard notes

• Labs: Tuesday and Thursday at 2:30 – 5:30 PM in WH 319

– Measurement experiments in groups of 3–4 people

– Acquire data in < 3 hours and spend majority of time on analysis and

reporting of results

– Assists with understanding the topics discussed in the course, some

reading ahead is required

Requirements

• Prerequisite: C or higher in MATH 2425 (Calculus II)

• Familiarity with Excel/MATLAB is helpful

• R.S. Figliola and D.E. Beasley, Theory and Design for

Mechanical Measurements, 5th ed., Wiley, 2011.

(hardbound)

or you can choose to buy the less expensive abridged

version (softbound) available at the book store.

• Lectures will follow the book chapters somewhat

Course Objectives

• To provide a background in engineering measurements and

measurement system performance.

• To convey the principles and practice for the design of

measurement systems and measurement test plans,

including the role of statistics and uncertainty analyses in

design.

• To introduce data analysis, reduction, and reporting of

results through formal reports.

Experiments…

• …they are an exciting part of engineering, but they can be

expensive and must be carefully planned from the facility

to the projected data analysis

Mars Science Laboratory

Pulsed detonation engine

Outline of Lectures

• Technical report writing and presentation of data

• Measurement methods for hardware and software

• Signal characteristics

• Measurement system behavior

• Probability and statistics for measurement systems

• Uncertainty analysis

• Experimental planning and practical measurements

Example Outcomes

• Improved communication of data (what to include in a

professional graph and report)

No! OK

Example Outcomes

• Understanding of statistics so experimental data can be

reported with the correct level of uncertainty (error bars)

Example Outcomes

• Understand how to collect frequency domain information

from signals

Example Outcomes

• Understand how to select measurement equipment; types

of instruments (both measure fluid velocity below)

Cup anemometer

http://en.wikipedia.org/wiki/File:Wea00920.jpg

Particle image velocimetry laser sheet

Outline of Labs

• A separate introduction to the measurement labs and the

required safety briefing will be given next week during the

lab time that you are enrolled in

• Labs begin next week and are performed every week until

completed

• Example labs: metrology, digital measurements, flow rates,

structural dynamics, heat transfer, LabVIEW programming

Assignments/Exams

• Homeworks (~ 6): Cover basic topics from the lecture

notes and textbook, mix of easy and more challenging

problems

• Lab reports (7): Formal reports of lab experiments

• Midterm and Final exam: Multiple choice questions and

short calculations

Grading

• ~6 homeworks 25%

• 7 labs 35%

• Midterm 20%

• Final 20%

• Total scores > 90% definitely receive an A. 80 to 90 B. 70

to 80 C. 60 to 70 D.

Late Assignment Policy

• Missed labs and exams must be made up immediately and

subjected to tardiness policy; – penalty for missing a lab

with no prior notice given to the TA. It is highly

recommended that you contact the instructor or TA if you

believe you will miss a lab or exam.

• One week given for grade appeals after an assignment is

handed back

• Late homework assignments will not be accepted. Grades

on assignments handed in one day late will be reduced by

20% of the total grade. Two days late, and the grade will

be zero.

Classroom Expectations

• Labs are performed after the lecture

– Lecture time ≠ time to complete lab report or homework in class

• Class participation is expected

– To attend class except for documented emergency

– Arrive on time and stay for the whole period

– I will take attendance

– 4 absences = grade reduction

– 9 absences = F

Expectations of Students

You alone are responsible for mastering the material presented in

this course for your own future use.

The instructor and teaching assistants are here to help you master

this material.

If you do not understand something presented in the class, it is

your responsibility to ask questions in class or seek help outside

of class.

A lab course offers the opportunity to witness and analyze

phenomena that you have studied or will study in other courses.

Successful completion of a lab course has always required a

student to spend significant time in the lab and writing reports.

Extra Notes

• Check Blackboard for additional handouts about report

writing, unit conversions, plagiarism cases, graphing, etc.

Americans With Disabilities Act

The University of Texas at Arlington is on record as being committed to

both the spirit and letter of federal equal opportunity legislation; reference

Public Law 93112-The Rehabilitation Act of 1973 as amended. With the

passage of new federal legislation entitled Americans with Disabilities Act

(ADA), pursuant to section 504 of The Rehabilitation Act, here is renewed

focus on providing this population with the same opportunities enjoyed by

all citizens.

As a faculty member, I am required by law to provide reasonable

accommodation to students with disabilities, so as not to discriminate on

the basis of that disability. Student responsibility primarily rests with

informing faculty at the beginning of the semester and in providing

authorized documentation through designated administrative channels.

Academic Dishonesty

It is the philosophy of The University of Texas at Arlington that academic

dishonesty is a completely unacceptable mode of conduct and will not

be tolerated in any form. All persons involved in academic dishonesty will

be disciplined in accordance with University regulations and procedures.

Discipline may include suspensions or expulsion from the University.

Scholastic dishonesty includes but is not limited to cheating, plagiarism

collusion, the submission for credit of any work or materials that are

attributable in whole or in part to another person, taking an examination

for another person, any act designed to give unfair advantage to a student

or the attempt to commit such acts. (Regents Rules and Regulations, Part

One, Chapter VI, Section 3, Subsection 3.2, Subdivision 3.22)

Presentation of Data in Graphs

Modified from “A pictorial guide to good graphing style” by Andrew Mizener, 2011

Introduction

• The objective of an experiment is to answer a question

(i.e., what does device A do at X, Y, Z conditions?)

• Answers to the question are usually in the form of data,

which must be graphically depicted and explained in a

technical report

• Excel graphs with default options are not acceptable for

professional communication of results

Bad Graph Example 1

Bad Graph Example 2

Graphing Requirements

• Size - The plot must be large enough to read in a printed

report. Plots both on their own page and in line with text

are acceptable. The text size in the plot should be similar

to the text of a report.

• Labels for axes - Axis labels should be descriptive and

have the appropriate units included. Axis labels without

units will confuse the reader.


• Titles – In a document, graph titles should be centered

below the graph and include a figure number.

• Ranges and scaling for axes - Limit the axes to the

minimum range necessary to display all the data.

– Add axis hatches so that the data can be reasonably read, but not so

many that they are unidentifiable.

– Select reasonable spacing for major and minor units


• Symbols for data and lines for functions - symbols should

of a reasonable size and color so that they are easily

printed out to read

• Generally, symbols are included only when you are

plotting a scatter of data.


• Lines for functions

– Dotted and dashed styles can be used to aid in

differentiating lines in close spacing, but should be

scaled such that no information is lost.

– Take care if printing in black and white since the color

doesn’t always translate to grayscale.


• Grid lines – These are usually not necessary. They might

be used with a logarithmic plot.

• Legends – Legends should be included when you are

plotting two or more data sets on the same plot.

– Move the legend inside the plot area to a space where no data is

plotted

– Legend entries should be descriptive. For example, “α = 5°”,

“Adiabatic Case”, etc. are good. “Series1” is not acceptable.


• Background color – There should not be a background

color.

• Borders – There should be no border around the entire

plot. A border can be put around the axes (see Good

Example 1), but that border should have the same color

and weight as the axes and hashes.

Good Example 1

Good Example 2

Experiments and Models

• Experimental data are usually compared with a model

equation

• If so, it is customary in publications to plot the data in the

form of points while the model is plotted with a line

Good Example 3

Data Points and Trend Lines

• Lines are often fit to scattered data to show the trends that

are occurring.

• If you fit a trend line, make sure that the line type chosen

(linear, quadratic, exponential, etc.) corresponds to theory.

• For instance, drag versus velocity points may have a

quadratic line fit since, in theory, D increases with u2.

Fitting an exponential line would be incorrect.

Example 4

Notes on Technical Report

Writing

This summarizes handouts online by Prof. Lu and Baker and Mizener

• A scientific experiment, no matter how

spectacular the results, is not completed until the

results are published.

• A cornerstone of the philosophy of science is

based on the fundamental assumption that

original research must be published.

• Only then can it be authenticated and added to

the existing database that we call scientific

knowledge (engineers use this knowledge to

design devices).

Report Structure

• In this course, report formatting is similar to

the conventions of academic journals.

• Most articles typically have an abstract,

introduction, methods, results and

discussion, and conclusions.

• These sections are followed by references

and, if needed, appendices for detailed

derivations of equations or data sets.

Title

• Should consist of the fewest possible words that

adequately describe the contents of the paper

– should be accurate, succinct but not vague.

– it is the first thing that is read and will

“make” or “break” the paper as a reader scans

through the pile of reading material that he or

she is inundated with daily.

Authorship

• Credit the persons performing and writing

up the work.

• Ranked in decreasing order of importance

to the work

• The inclusion of courtesy authors (i.e.,

adding a famous person) is strongly

disapproved by all professional societies.

• Usually no more than 10 authors in MAE

journals; some large projects generate

papers with hundreds of authors.

Abstract

• The abstract is typically 100–200 words and is

mostly written in the past tense.

• It assists the reader in assessing whether or not

he/she is interested in reading the paper

• 1) state the objectives and scope of the

investigation, 2) describe the method, 3)

summarize the results, and 4) state the major

conclusions.

Introduction

• Nature and scope of the problem investigated.

• Literature review of related work (also

establishes your work to be an original

contribution).

• Method of investigation and statement of work.

• Summarize the main results and conclusions.

Methods or Experimental Setup

• State methods used with applicable theory and

analysis.

• The goal is to give a reader enough information to

repeat the experiment to verify results (especially

if you report that neutrinos move faster than the

speed of light).

• Do not use an “instruction manual” language style.

Results and Discussion

• Present in a logical order with subsections if needed

• Don’t include results with no explanation. Discuss

graphs and tables as they are added to the report.

• Clearly explain the significance of the results.

• Discuss similarities and differences between current

observations and previous work that is referenced.

Conclusions

• Similar to an abstract, but not a copy of it.

• Make concrete statements that are supported by

results.

– “The Seebeck coefficient seems to be about 50

mV per kelvin for the metals starting around

300 K and ending around 1500 K.”

– “The Seebeck coefficient is 51 ± 2 mV per

kelvin for the metals over a temperature range

of 300–1500 K as indicated in Fig. 4.”

Acknowledgements

• Not needed in this course, but appears in

publications.

• Acknowledge co-workers that made

contributions, but not sufficient enough to

be co-authors.

• Acknowledge funding sources.

References

• Must be cited in the main text (usually with a

number [1], [2], etc.) and then added at the end

of the paper.

• Lots of references do not make a better paper,

but they should be thorough.

In text

In refs.

Fonts

• There are lots of fonts available, but only a few

are used for technical writing

(usually Times New Roman)

•Example of a bad font for technical writing.

• Variables are italicized and can be English or

Greek letters

• The text is usually justified right.

A Few Notes on Style

The handouts have many more details. Below

are common mistakes in lab reports.

• Tense: You DID perform the experiment.

You ARE presenting the results. The

procedure happened in the past.

• Use 3rd person tense. Don’t use “I,” “me,”

“we,” etc.

A Few Notes on Style

• Numbers less than 13 are typically spelled out.

• Put a space between the number and unit.

• Units named after a person are capitalized only

if they are abbreviated. All units are lower case

if spelled out. For example, the force is 1000 N

or 1000 newtons. (temperature units are an

exception).

• All equations should be centered with a number.

Paragraph Structure

• The main idea presented by a paragraph can be stated in the first or last sentence. Using first sentence main idea statements allows the reader to quickly determine what information is in the report.

• The last sentence is most effective as an introduction to the next paragraph (improves the “flow” of the writing).

2381 Su14 Lecture 1 Introduction

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