Best and Worst Aspects of Course–Your Opinions

I’ve just completed grading the essay question that each of you completed on the exam.  I’m happy to say that all of you took it seriously and thus almost everyone received a “10 out of 10”.  Only a few people had entries that were too short or not read for grammar, thus losing portions of a point.  One or two, sadly, did not complete the question at all and thus received no points.

Since I use this question as a prime way of learning what’s good about the course and what needs improvement I keep a tally while grading of “Best” things and Worst things.  Here’s a summary of what I learned.

Best Aspects of the Course – by number of mentions above 5

• The diversity of the course, introducing you to all aspects of what the department does - 35
• The lectures – mostly for their variety and enthusiasm – 35
• Discussions – 25 (though 3 disliked them)
• Site Visits – 22
• The labs – generally (and see below for problems) – 15
• Course design overall - 8
• Connection of theory to reality - 6
• There were quite a variety of aspects with fewer than 5 mentions including specific lecturers, specific labs, aspects of the administration

Worst (or problematic) Aspects of the course

• Various aspects of the labs, though a maximum of 6 in each area
  • Lack of detailed rubrics, guidance on some labs
  • Lab instructions not clear
  • A variety of aspects with less than 5 mentions including: Discussions, lab instructions, dull lecturers, specific labs.

Some Statistics

• 48 people chose to write exclusively about the Best
• 2 chose to write exclusively about the Worst
• 31 chose to write about the best and worst
• Longest essay – 624 words
• Average essay – 276 words

To get a sense of your overall satisfaction with the course I rated each essay on a 1-to-7 scale with one being “intense dislike” and seven being “best course of the term” – a four being neutral.  Using that scale your rating was 6.1 out of 7 overall.  I will look at the course evaluations when you complete them to see how they match this rating.

Here’s a link to the overall Final Assessment Comments

Take-Home Assessment – Comments

Some of you may wish to know how the class performed on the final Take Home Assessment. Here are some comments

The Process

• I graded all the essay questions myself – almost everyone was careful and received full credit
• I reviewed the “item analysis” provided by BbLearn.  It looks at the performance on each question to see if there problems because they were poorly written or possibly required material that was not presented in class.
  • As a result of that review I decided to add 8.7 points to each person’s raw score to make allowance for possible lack of clarity, although I found no questions that I felt were wrongly stated.
  • The result of this increase in the exam is reflected in the column –CAEE-201 TakeHomeAdj

Some comments on questions where there were difficulties.

• Learning after Graduation – It’s almost certain that you’re going to need to go on learning throughout your career as an engineer.  Many of you chose answers that indicated your thought there wouldn’t be much later learning.
• Heat Transfer Calculation – this was the same basic question as in Lab #1
• Nested IF Function – This was admittedly a difficult question, but it was directly based on the hydrology lab.  Learning to use this kind of logic will almost certainly be beneficial in your engineering career.
• Gas Concentrations – A key result of the IAQ lab was that you cannot have all things – low ozone and low CO2 merely by ventilating.
• Revit Type – Revit is BIM software, not a sketching or drafting tool.  When I Googled the word Revit the first entry stated that as I did in class.
• EER – EER is a ratio of BTU/Watt-Hour – It’s a measure of efficiency of an air conditioning system.  it is NOT dimensionless as it is used. 
• Member Weight Calculation – It’s surprising that a number had difficulty with this one.  You needed to calculate the volume and multiply by the density, being sure to watch the units of volume to work in either in^3 or ft^3.

Short Essay on Best or Worst Aspect of CAEE-201

I covered this in a separate post

Units for Bridge Lab–Sources for Calculation Problems–Dimensions and Micro-Strain

There are two potential sources of error on the bridge lab, one of which is probably not as obvious as it ought to be.

#1 Consistent Units

It’s easy to forget to convert your lengths into consistent units – usually inches.  That often introduces big errors.

 

#2 Micro-Strain

The data for the lab are marked “ue”.   It is probably not obvious that this means the real strain is 10^6 times smaller than shown in the excel spreadsheet.  It’s shown that way in the spreadsheet to avoid showing many, many zeroes before the significant digits.

So: a strain shown on the spreadsheet as –1.23 ue  is really –1.23/10^6 = 0.00000123

Lab-9 T-P Bridge Questions

 

Questions

Are these problems that need to be done for the lab? 

(2) Monitor the strain gage data under traffic and inform the engineer operating the data acquisition system when a truck approaches so they can record the strain time-history.

(3) Take a photograph of the truck that caused the measured strain in the top chord and note the lane (upstream, downstream or center) it occupied. 

      (8) Is the computed truck weight less than the legal limit?   (Where are we to find the legal limit?) 

Added Later

And is the max stress level the values in the one in the -30 range or in the 4-5 in/in range

 

Response

#2 & #3 – We provided the strain gauge data and the truck photograph this time

#8 – As Dr. Moon said in his lecture and I said in class today you can find this by a Google Search looking for Federal truck weight load limit or something similar.

Max Stress Level – It’s up to you to determine the max stress level.  Usually a maximum (in absolute terms) is the greatest departure from the average.

Bridge Calculation Question

Question

I find the figure 'Truss Chord Diagram' very confusing. Specifically, I am unsure as to where each label is referring to in regards to the information in the 'T-P Lab Description' file. 

The description states:

One Cover Plate: 28 in. by 1/2 in. è Area = 28in(1/2in) = 14 in²

Four Angles: 6 in. by 4 in. by 3/8 in. è Area = 4*(6in(3/8in)+4in(3/8in)) = 15 in²

Two Webs: 24 in. by 1/2 in. è Area = 2*(24in(1/2in)) = 24 in²

Two Plates: 12 in. by 5/8 in. è Area = 2*(12in(5/8in)) = 15 in²

I would like to know where these pieces are, as I see two labels for Web Plate 1 and Web Plate 2 for example, and do not understand which label goes to which piece. 

Follow-On Question: 

My confusion is more about the difference between a "webplate" and "web" and "plate." The diagrams show "Webplate" but the information in the attached description lists these separately. 

 

Response

The Truss Chord (The top one for your problem) is a “built-up” member composed of a series of steel pieces.  The “example” in the instructions for the lab is supposed to help you understand how to read the labeling on the drawings.  Our expectation is that you’ll look at the drawings and find the label that is similar to the one in the example for the truss chord where the strain gauges are labeled.  You then calculate the cross sectional area of the truss chord as in the example.

There is a diagram in the documents attached to the assignment that shows the typical assembly of a top chord.

To perform the calculation you don’t actually have to know where each piece is in the built-up member, although it’s nice to be able to interpret the code to be able to visualize it.

Web is the technical term for  the long middle piece between the two shorter parallel pieces in an “I” or “H” structural member.  Flange is the term for the shorter pieces.

Webplate probably should have been two words meaning “a plate that forms part of the web of a built-up member”

About the Online Final Assessment

Where Do I Find It?

• Click on the “Quizzes and Exams” menu item in the course website in BbLearn

When It’s Available

• Opens – Midnight Thursday Morning  6/5 
• Closes – 11:59PM Sunday Evening 6/8

How Much Does It Count?

• 18% of the total grade

What is on it?

• 75% Multiple Choice + True/False + Multiple Answers (more than one answer per question possible)
  • These are drawn from the lectures and the labs in the course.
  • A few require you to be careful in your thinking, but most are straightforward.
• 15% – Calculation Questions based on the labs
  • The description and logic for calculating the answer are the same, but each student will see different numbers
• 10% – 200 words or more on the Best or Worst (or Both) Aspects of CAEE-201 – graded on being specific, not on your opinions.

May I take It More than Once?

• Yes, you may take it up to three times – each time you have 3 hours
• You will not receive your score after taking the assessment– not until I have graded the essays after the assessment closes
• You may not save and resume during one instance of the test.
• Each time you take it the numbers for the calculations and the order of the questions will probably be different.
• You should assume that we will use the grade from the last instance that you take the assessment.

Lab-9–Tacony-Palmyra Bridge Questions

Questions

#1 What files do we submit to Bb Learn for this assignment? If it is a singular Excel workbook, then are we to create the Memo sheet from scratch? If not, what other files are we to complete?

#2 When analyzing the strain values from the sensors, I noticed that a lot of them, including the largest ones, are negative. Does this imply that the strain is in compression? Are we to use these larger negative values in our calculations and disregard the negative sign?

#3 Which distribution factor are we supposed to use? Are we to use just one? Or do we calculate the weight of the truck three separate times for all three scenarios?

 

Responses

#1 – As in any work situation you are to submit what is required to address the problem.  We left it more open.   If it were me, I’d submit a single Excel sheet using what I’d learned from the other labs.

#2 – Think about the truss and how it bends.  The bottom wants to stretch and the top wants to compress.  Negative values indicate compression.

#3 – You are to look at the information provided and decide which lane the truck is in and thus which distribution factor is appropriate.

Geotech Lab tips

Chart:

- Profile - should be a continuous line or curve

- Profile - do not use Trendline (Layout Analysis tab); this feature is not intended for our type of Labs. Use Chart types from Design Type tab.

- When you produce datapoints for your chart please use and leave Excel formulas so we can see how you obtained them

- Axis title and labels should be on the same side if possible

Format:

 - When preparing a table for a chart please keep it formatted, e.g., borders, headings, column names etc. Points will be deducted in the "Format and clear organization of the entire document and its parts" line

- Equations as ∑ _(i=1)^n  γ_i Z_i = γ_1 Z_1 + γ_2 Z_2 + γ_3 Z_3….+ γ_n Z_n  are not in any accepted notations and are not intelligible. Notations as σ(v) = Y(1)Z(1) + Y(2)Z(2) +Y(3)Z(3) are slightly better but still, have ambiguity, and may not be understood properly by a person distant from this specific lab and lecture.

- Use named cells

Memo:

- Keep Memo language formal; avoid words "like", "kind", "us engineers",

- Grammar - write Memo in a text processor and Copy-Paste into Excel text box. Excel does not have the spell check capability!

- If you decide to report key equations in Memo please report factors used, e.g., F = ma, where F is force, m is mass and a is acceleration

Units:

- When establishing a new data column please indicate units

- When you apply multiplication or division operator there's a good chance your units will change!

Calculations:

- Don't round intermediate results
- Specific Weight (or Unit Weight) of water is 62.4 lb/cu.ft. (changes with temperature) 

General feedback:

- Please read the Lab instructions and the lecture materials before the Lab, come prepared!

- Don't wait to submit  until 09:50 when many other students may overload the server and you may not be able to submit successfully

- Charts have a random place on a chart Quest

- When reporting units, please avoid extraneous characters, e.g., (psf_)

IAQ and Pollution labs

A few notes about the IAQ lab and the upcoming water pollution lab.

IAQ:
- This lab was probably the most lopsided so far.  For many people, one mistake in this lab had a domino effect on the rest of the results.  If the rubric has that a value is "correct", it unfortunately does not leave room for partial credit, even if I can trace your work back to the error.

- Many people either mistyped or mis-converted the total heating gain from 280 kBTU/hr, should have been 280000 BTU/hr

- Many people mis-converted the electricity consumed by the chiller by using the BTU to watt-hr given.  However, the Ecooling has units of BTU/hr, and EER has units of BTU/watt-hr, so Ecooling/EER has units of (BTU/hr)*(watt*hr/BTU), or watt*hr/hr or just watt.  The instructions asked for kwatt*hr/hr, which required dividing by 1000.

- There seemed to be some confusion with the flow rates.  Put simply, Qe must always equal Qv.  The equation on the first page that Qv+Qr=Qe+Qr indicates this; if you subtract Qr from both sides of the equation, you're left with Qv=Qe.  Thinking about it physically, if if Qv was > Qe, there space would be pressurized, and if Qv were < Qe, it would be under vacuum.  Since we never want either of these, Qv and Qe will always be equal.  For question 3, the CO2 concentration should have decreased exponentially with increasing ventilation flow rate.


Water pollution lab due this week:
- Please make the memo a sheet in your workbook, formatted in the same way as previous memos, and answer all of the questions as described in the rubric.

- Format section: this is a more important section this time, please remember that your name and date should still be on each page.  On a similar note, organization is extremely important.  Each piece that is on the rubric should be clearly labeled in your document.

- Units are vitally important for this lab.  Make sure you clearly label all the conversions you make and label every result

- During lab, there were a lot of problems with entering the formulas into Excel.  Here's a couple features of your results to make sure you're on the right track:

1. The peak concentration should be about 10^-2, variable to the time step you use and different between Pottstown and Norristown, 
2. The rise and fall of the concentration should have about the same slope - if it is steeper on the upslope than the downslope, you've got a calculation error
3. Both Norristown and Pottstown concentrations should peak and return to virtually zero in the time specified

Again, please let us know if you have any questions!

-Anita

HVAC/IAQ lab formula

Hi everyone,

Two comments:
1) We got a question from a student and am posting the response here in case others are having the same problem:

Q:  In the Week Four HVAC/IAQ Lab Instructions, the equation for energy carried by airflow only shows up as

Eairflow=m×[]
when I download it.

A: The formula for Eairflow is m*[0.24T+W(0.45T+1061)]

Where m should be m with a dot over it as the mass flow rate, T is the temperature, and W is the relative humidity as described in the parameters of question 2 of the Excel file.

2) EDITED: I had a previous comment here before which was incorrect, sorry!

-Anita

Grading Notes–Attendance and Calculation Method

I’ve brought the attendance grades up to date through week-4.  You should check the attendance score and other grades now rather than at the end of the term.

Notes on the grading:

• Attendance scores are “raw”.  At the end of the term I will make an allowance for one missed lab and two missed lectures – a total of three.  This will improve your attendance score in the final grade calculation.
• Discussion and Lab scores are already adjusted to drop the lowest score in calculating the running total. 
• HOWEVER.  If you didn’t turn in a lab or discussion that one isn’t included in the calculation during the term.  IT WILL be included as a “0” at the end of the term so your overall grade could decrease

Week-4 - Rec Center Tour - Lab Locations and Times

This week we’ll be touring the Rec Center AND having time in the lab to address the calculation assignment of the week.  You should plan to be involved the whole two hours of your lab period.

Note that we will meet outside the East entrance to the Papadakis Integrated Sciences Building (PISB) (inside if raining).  Here’s a map showing where we’ll meet and where we’ll go.

• Wear flat shoes (NOT heels) – we’ll walk on sensitive surfaces.
• We’ll take attendance during the tour

 

Time & Location

Lab	Last Name	Time	Location	2nd Hour
060	A-L	10:00	PISB	Randel-327
060	M-Z	10:00	Randel-327	PISB
061	A-L	12:00	PISB	Randel-327
061	M-Z	12:00	Randel-327	PISB

Hydrology lab corrections/clarifications

Hi everyone,

Just a couple important notes from issues that came up in lab today:

A) On the Excel file, question 2, the first line is supposed to be an example.  However, it is incorrect on two counts.  First, the data you inserted from rainfalldata.xlsx has rainfall data for 1/1/12, and that should be included in your calculations.  Second,  "Outputs" (column E) and "Amount supplied by the municipal supply" (column H) are incorrect for that day.  The outputs in ft^3 should have a value of 1604 (but be sure to show your work, 0 credit will be given for typing that number).

B) It has now been fixed, but if you downloaded a copy of today's lab lecture notes before around noon today, there's a typo on the 4th slide: the volume of the cistern should be calculated as 15000+750*LettersLastName, not 1500+ 750*LettersLastName.  Sorry for the confusion, if you see any other such contradictions, please ask for clarification - we do make mistakes!

C) The rainfall.xlsx file has two tabs: one has the precipitation in inches, the other tab has different units.  You'll get the same answer if you use the correct conversion for each case, but please be aware of the difference - starting with the values in the inches tab will be easiest.

D)  Please note (as the instructions do) that for question 3, the x and y axes should be labeled, and that you need two separate plots.  In the example, the x-axis is day of the year, but there are many ways to display the date, you may choose a different one.

We've also gotten a few questions about the lab feedback on BBLearn: when you look at the assignment on BBLearn, the preview you see is for what you submitted, not our responses.  To see the responses, click the file on the right side, should be a file starting with your last name and ending in "graded" or "grd"

Please let us know if you have any questions!  We would much rather answer your questions before labs are due than take off points while grading.

-Anita

Lab 1 feedback and notes on memos

Hi everyone,

We've finished grading the first lab and you should be able to see your grade and download our responses via BBLearn.  If you have any questions, let us know or talk to us in class on Friday.

A few general comments: 
- You should NEVER type values into Excel, with the rare exception of multiplying or dividing by 1000 (like changing to kips in this lab).
- Lots of points off for sig figs and notation: 2 to 3 sig figs will be criteria for the entire term
- Name and date on each page: if the header is not visible, switch to page layout view

And a few notes on the memo: 
- It is 100% okay to be direct and say "The purpose of this lab was __" and then continue on from there.
- If you're stuck on what to write for the purpose or details section, look again at the grading criteria for each question: if we're looking for it in the grading criteria, chances are we wanted you to learn something from it.
- For details, you do not have to provide details for every question, it should be a summary, not a step-by-step procedure of what you did.
- The implications and limitations are an attempt to have you look at the lab in a broader view.  Think about: what are the broader consequences of what you learned (will you use it in the future? do your results indicate success or failure? how does this type of system work?) and what kept you from being more accurate or certain about your results? (did you make simplifying assumptions that are too simplistic? what piece of data was limiting? where do you think the largest source of error comes from?)
- These should have a formal tone, and should never be in first person.  A previous TA used this great example: "We took a tour of the Tacony-Palmyra Bridge and it was so fun to get hands-on experience and measure the strain gage distance for ourselves."  A better way to state the same activities: "A site tour of the Tacony-Palymyra Bridge was conducted and field measurements were recorded to determine the strain gage distance."

If you're having problems with the memo, somegreat source for writing business memos:
http://owl.english.purdue.edu/owl/resource/590/04/

http://www.writing.engr.psu.edu/

You can always get help here at Drexel by utilizing the Writing Center:http://drexel.edu/engphil/about/DrexelWritingCenter/http://drexel.edu/engphil/about/DrexelWritingCenter/workshops/
They also have various workshops you may register for during the various terms:http://drexel.edu/engphil/about/DrexelWritingCenter/workshops/

Please remember to include all three documents (.rvt file, .docx file, pdf) when you submit your Revit lab this week!

See you back in the normal classroom this week, Randell 327,
-Anita

Lab-1 - Help with Question 5b

Question

“would the first blank where it asks for the Air BTU/CF-DegF be solved by dividing the air specific heat by the air density?”

Response

There are several ways to address this kind of problem where you’re facing new material.

1) Check the units.  Given the information available what combination produces the units of the desired answer.  In this case that’s BTU/CF-DegF.

2) Think about the physical reality – the more meaningful approach.  I suggest thinking about one cubic foot of air. 

• What do we know about it? 
• It has a mass, which we can calculate with the given information
• It will take a amount of heat to raise it one degF
• We can calculate that if we know the mass because of the other given information
• With those two you have the answer
• The same approach will give you answers to the other parts.

Revit Lab–Hints for the Lab

Below are the hints for the lab.

• Save your file to desktop in the cadlab to avoid losing it in your machine 
  • Email it to yourself, or use a flash drive, or DropBox
• Videos online are helpful if the text instructions aren't clear
• If you have only 3-4 letters in your last name - multiply by 20 to get the length of your wall.
• Make walls go to 2nd level 
  • set "property" before  drawing, but you can change later
• Remember to put on a dimension 
  • under the annotate menu
• Not all things in the videos are required for this lab

Suggestions About Using Revit

Questions: – From Previous Year, but still appropriate

1. Hello, I have one question about the Revit Lab. I followed the videos, made the Revit model and the output sheet. How do I convert the sheet to a PDF file from Rivet?
2. Also, we're supposed to submit the actual Rivet model, meaning we have to submit the actual file we made upon starting the Rivet videos? Just a little confused, hope you can clear that up thank you.

Response

#1 You need to “Print to PDF”.  On the machines in the lab there is a PDF printer installed – just choose it when you’re printing.

If you’re doing this on your own machine you’ll need to install a “PDF Printer”.  There are multiple free one available.  TechSupportAlert is a good recommendation source – Here’s their link to PDF Printers and tools.

#2 You are to submit three things for this assignment

• The actual Revit File
• The PDF of the “Sheet” that you’ve created
• The Word document defined in the assignment.

Discussions–How Many Other Students to Review?

Question

If we posted first in our thread, do you still want us to reference other students' posts?

Response

I’ve revised the discussion page to address this question explicitly.  Here’s what it now says.

Each week you are to prepare for the week by reading two professional-level sources that give material related to the topic for the week.

You are to answer some standard questions about it and give some opinions.

You will enter that into one of the discussion "topics" for that week in BbLearn. You are also to read the entries of other students who have read the same primary source material and react to those entries in an appropriate way by editing what you've written to react to what those before you in your topic have entered.

We expect you to comment in some way in your discussion post on the work of at least two other students.

• If you're the first to post in your thread you do not need to comment on other student's work - but you do need to state that you were the first to post.
• If you're the second to post you comment on only one.
• We'll check and deduct points if we find suspicious claims.

Lab 1 tips

1.       Due - 10 AM Friday a week after the class, for both sections.

Excel:

2.       Named Variables - don't use spaces. Good practice -- capitalize 1st letter of a word, e.g. MyFirstName. If you need to eliminate an unwanted named variable use Ctrl-F3 shortcut.
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 on-line training.
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.       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.
9.       Note:: Some questions have non-conforming unit notations, it is alright to correct them when Excel allows to.
10.   In Question 5 --  BTU/CF-DegF means Btu/ft³∙°F (and similar to it cells).

Memo:

11.   Writing Memo -- consult Prof. Mitchell's blog entry and the links he refers to.
12.   Memo subject -- "Meaningful phrase that announces the topic".
13.   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.
Misc.:
14.   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.
15. 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 result is not a credible reference. 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. I hope the ASHRAE people won't be considering it as a serious breach of copyright. It can be cited   (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 is also a good explanation of the unit-factor method (and of course we never refer to Wikipedia in memos and reports).

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

Discussion Posts–Addressing Other Student’s Work

Question:

I would like some clarification about how you and/or the graders would like us to respond to other students posts. Should we use the "Reply" button underneath another students post, or should we include our responses in the body of our own post?

Response:

You want to make sure the grader knows that you have read and considered other people’s work.  The best way to do so is incorporate references to other people’s posts in your own post.

• e.g…… I agree with Jonathan Doe’s opinion about the importance of Geotextiles in Geotech, but am concerned that we don’t have good data on how they will deteriorate over time…………

Week-1 &2 Lab Schedule Information

Week-1 - In the Default Space – Randel-327 (corrected 4/3/2014)

• Bring your laptop or other device on which you can work with an Excel Speadsheet
• Look at the lab beforehand - have your questions ready for the TA

*******************************************************

Week-2 - Revit Lab

Where: CAT-167A – Google Map

Because of the limited number of computers in the lab we’ll split the labs into 1-hour blocks

Times

Lab Section #	Last Name Begins With	Time
60	A-L	10-11
60	M-Z	11-12
61	A-L	12-1
61	M-Z	1-2

 

Bring

• Yourself
• Lab – Please look at it first
• Laptop if you’d prefer to work on your own machine

About You

You might be interested in the composition of this class.

Breakdown By College and Major

 

Breakdown by Class

 

Experienced Students

Note that anyone who feels they don’t need this class because of prior experience can talk with Prof. Mitchell.  We may be able to allow you to substitute another, more meaningful, class for it.

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 – I use Feedly.  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.