Discussions - Addressing Other Student’s Work

Question:

I am a student in your CAEE 201 class and I was wondering if the replies had to be done in the section you posted in. I was the first to post in my discipline, Environmental Engineering, so I was unsure if I was supposed to post a reply in the other disciplines or not. Please get back to me when you can.

 

Response:

The intention was that most students would include reactions/comments about other students’ work in their own post.  The following notes may be helpful:

• If you’re the first person to post in a section (e.g. Environmental Engineering), then you do not need to address any other student’s posts
• If you’re the second you only have to address the first – and so on up to the number required.  You only need to consider within your section.
• If you wish to make a comment attached to another person’s post that is fine, but please structure your own post to indicate to the grader that you’ve done so with names and sections so they can find that post easily.

Seeing Blog Summary in Firefox and Chrome

Recent versions of Firefox and Chrome can block the appearance of the box summarizing the blog on the home page of BbLearn.  IRT recently provided information on the simple fix for this problem.

Firefox recently made a change in it's security features and it is now blocking what it has been told is unsecured content.  This is the issue that is featured on the homepage of Learn of the left hand side.

Here's a video of me enabling it.
http://screencast.com/t/Wat6ROIw

Chrome will do a similar thing, but the shield is on the right hand side.

IE too, but it's a questions posed in yellow at the bottom of the screen and you have to answer the question such that unsecured content is allowed.

Lab 1 feedback from the TA's

1.       Due - 10 AM Thursday a week after the class, but also check with current Syllabus.

Excel:

2.       Named Variables - don't use spaces. Good practice -- capitalize 1st letter of a word, e.g. MyFirstName
3.       Troubles with Excel -- please refer to Excel help and tutorials; it is the best and most effective solution. You can also try the IRT MS Office training workshop.
4.       Remember, Excel is a computational software; it is designed to do computations for you.
5.       Excel allows leaving comments in cells - you can use this feature when you feel a comment may add clarification.
6.       Consult the Post-It-like notes and Instructions attached to question pages for grade tips.

Units and sig figs:

7.       Conversion factors column does not need formulas; it needs conversion factors which are constants. No real rule for conversion factors sig figs.
8.       Prof. Mitchell is OK with an extra sig fig. I encourage using a good judgment when deciding to have it or not, and not leaving an extra digit across the whole exercise.
9.       Units spelling -- refer to literature e.g. , NIST Handbook 44 - 2013 Edition, Appendix C - General Tables of Units of Measurement  OR NIST Special Publication 330, 2008 Edition. International System of Units (SI). Both are by National Institute of Standards and Technology, Washington, DC.
10.   Note:: Some questions have non-conforming unit notations, it is alright to correct them when Excel allows to.
11.   In Question 5 --  BTU/CF-DegF means Btu/ft³∙°F (and similar to it cells).

Memo:

12.   Writing Memo -- consult Prof. Mitchell's blog entry and the links he refers to.
13.   Memo subject -- "Meaningful phrase that announces the topic".
14.   Memos should have a professional tone. Limitations of the lab are not your own personal limitations or struggles but rather specific caveats related to assumptions you had to make in order to complete your calculations (ex: did you actually measure your shoulder width with a ruler?) See the earlier entry on the course blog for additional suggestions.
15. Some labs have specific questions that should be answered in Memo.

Misc.:

16.   If you do not have a laptop, please look at the lab prior to class time and come to the class session to ask your questions.
17. If your computer does not have MS Office -- it appears that it is OK to do it in OpenOffice (save as .xls or .xlsx file), or maybe use CADLab machines.

Conversion Factors and Methods

Conversion factors could be seen as universal constants. Some of them are exact, like 1 inch equals 25.4 mm. Most of them don't have an exact value but rather expressed as a decimal fraction with 4-8 sig figs which is enough for most engineering applications without reducing desired precision.In the lab we had to find several conversion factors. It may be OK and definitely convenient to google it, but for the lab Memo and for professional reports a google search is not a credible reference. I think the best source of reference materials such as conversion factors is a relevant industry's handbook. For HVACR it would be ASHRAE Handbook - Fundamentals. An electronic edition of it is available through Drexel libraries, but for this large class' convenience I also supply a link to the Chapter 38 image file on my Google Drive (page 1 and page 2). I hope the ASHRAE people won't be considering it as a serious breach of copyright. It can be cited as ASHRAE (2009), 2009 ASHRAE Handbook - Fundamentals (I-P Edition), Chapter 38 Units and Conversions, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Another great reference would be ASTM/IEEESI-10-1997 Standard.The unit-factor method is a commonly used technique to convert a value from one system of units into another, or from one unit into another within the same system. Explore it more on KhanAcademy videos. Wikipedia article on it also is a good one on the unit-factor method (and of course we never refer to Wikipedia in memos and reports). Unit conversion is fundamental and essential to engineering disciplines!

References Style

ASCE recommends its authors to use Author-Date References.  I suggest that we adhere to this recommendation in the class.

Significant Figures and Rounding

The concept of significant figures (sig figs, s.f.) arises from the concept of physical measuring of a variable. Instruments we use have finite accuracy and reliability. For example, a desk ruler has least readable unit (least count) of 1 mm, while a common Vernier caliper can measure with accuracy of 0.02 mm. Thus the reasonably reliable length of a steel plate measured with the ruler could be 26 mm (two s.f.), while measured with the caliper would be 26.14 mm (four s.f.). If one has to add two measures, let's say a plate measured with a ruler and a plate measured with the caliper, the ±0.5 mm uncertainty of the first plate will dominate the uncertainty in length of the second plate ±0.01 mm. When that person reports the combined length of 52.14 mm he or she cannot defend the final precision up to 0.02 mm because the ruler's precision of 1 mm dominates. Side-note: some technicians and researchers state that many elementary measuring devices allow an (experienced) operator to estimate the measured value one figure beyond the instrument's least count. In our ruler example, we could estimate the plate's length as 26.1 or 26.2 mm (three s.f.)

Very often we have to use the measured values in various calculations which ordinarily give as answers with a long trail of decimals. While it is perfectly fine to carry the trails during a multi-step calculation, the final answer must be always rounded off and reported with a correct number of s.f. In other words, the accuracy of the final answer cannot exceed the accuracy of the least accurate measurements or data provided.  Four groups of different arithmetical "operations" have different rules of maintaining s.f. Those groups are Addition and Subtraction, Division and Multiplication, Logarithms and Antilogarithms, and Trigonometric functions.

Addition and subtraction can produce and answer with a higher or lesser s.f.

Division and multiplication results are limited by the data with least s.f. I have heard respected opinions that there's an exception to the division and multiplication rule. The opinion is based on the notion of fractional uncertainty: when an answer begins with a digit 1, the answer's accuracy would be preserved better if we maintain an extra s.f. than the original data with lowest s.f. I personally adhere to that opinion. However, I advice to proceed with caution - it appears that this "rule of 1" is not widely discussed and often omitted. Please consult relevant literature or specific industry's guidelines for further use.

In logarithm operations the mantissa determines the number of s.f.

For purpose of real life applications trig functions preserve the number of s.f. of the input variable.

A few words on rounding tie-breaks (when the "digit" we want to cut off is "exactly" 5, e.g. 26.145 or 26.14500 or 26.145000). Many disciplines use the round half up or round half away from zero rules. Both those rules are asymmetrical and lead to biases. In science the most accepted tie-breaking rule is round half to even. As per 09/25/2013 1900 the Wikipedia's relevant page has a correct explanation with an example.

My favorite intro text on s.f. with computational examples is Quantitative Chemical Analysis by Daniel C. Harris.

References:

ASTM Standard E29, 2008, "Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications," ASTM International, West Conshohocken, PA, 2008, DOI: 10.1520/E0029-08, www.astm.org.

Harris, D. C. (2007), Quantitative Chemical Analysis, 7 ed., 663 pp., W. H. Freeman, New York.

Michener, B.; Scarlata, C.; Hames, B. (2008). Rounding and Significant Figures: Laboratory Analytical Procedure (LAP). 7 pp.; NREL Report No. TP-510-42626. http://www.nrel.gov/biomass/pdfs/42626.pdf

About You

You may find it interesting to know the composition of the class.  Here’s the breakdown by college, major and year.

As expected, the majority of you are sophomores from the CAEE department, but there are a significant number of Business and Engineering Seniors and a sprinkling from other departments and colleges.

Memo Writing for Lab Reports

In past offerings of CAEE-201 the graders have commented repeatedly on how students have lost points in their lab reports because of poor understanding of what is expected in a Technical Report – we call it a “Memo” in most of our labs.  What follows is the description from “Lab Assignments” on appropriate Memo Writing.

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You will write many letters, proposals and reports throughout your career. In these labs we require a "memo" that in one page summarizes the key aspects of the lab. It's very important that you learn to write this kind of document well because you will be judged by your employer by HOW you say what you did as well as what you did - that's a reality. Here are two links that should help on writing good memos. There are many others available online or through your English instructors.

• The Content of A Technical Memo - PDF Document from Texas A&M giving good guidelines. Adapt it as appropriate.
• Language for a Technical Memo - WikiHow has good advice on appropriate language.

 

Keep in mind the following. The reader will want to know:

• Who did it
• What you did
• Why you did it
• When you did it
• Where you did it
• What tools/equipment/programs you used
• What you found
• What you conclude
• What uncertainties, reservations you have after completing the work
• What further work you would recommend (if any).

 

For language you can avoid most problems by:

• Write in "simple" language. Be direct and brief.
• Check grammar and spelling
• make use of language labs and other resources if English is not your native language
• Make use of MSWord's grammar and spelling checker - write there and paste the text into the memo
• Avoid colloquial or slang language

Your Work in CAEE-201–Requirements

The requirements for your work in this course spelled out in detail in the BbLearn pages addressing each.element.  This page summarizes that work.

Weekly Work

• Attendance

• We will take attendance at all lectures and lab sessions.  You will have a total of three “free” misses to account for illness or other reasons for missing the class.

• Discussions

• Post a “discussion” in BbLearn each Monday by the start of class addressing the week’s topic.

• Note that you’re to have read other student’s work and commented on it.

• Labs

• Go to the Thursday lab each week

• Download the lab from BbLearn and review it before the start of the lab session.  That lab session will be your only regular opportunity to meet with a TA to ask questions about the lab.

• The location and duration of the labs will vary through the term.  We’ll announce that week’s requirements in class. Some weeks we’ll have site visits.

• Submit your completed lab by the 10:00 the following Thursday

• The final lab will be due at the end of the last full week of classes.

End-Of-Term Work

• Take-Home Assessment

• At the end of the final full week of classes there will be an on-line assessment to be completed over the period of several days.  It will consist of questions drawn from the full term’s worth of work as well as short essay on the best or worst aspect of CAEE-201

About This Blog

We'll use this blog to post announcements and answer questions that are raised throughout this term related to CAEE-201.  We advise you to subscribe to it via an RSS reader such as Google Reader.  That way you won't have to go into BbLearn to see any changes.  There are many many blogs available on interesting topics.  A good place to search for others that may interest you is Technorati.