Archive for November, 2009
Running hot and cold in Apalachicola – steaming to cook clams and steaming to make ice
My wife and I are celebrating our 35th anniversary with a Thanksgiving week getaway on the panhandle of Florida. Later today we will enjoy a southern version of the traditional banquet, this one will featuring all sorts of grits – the chef’s specialty. I expect some oysters too – mainly harvested just down-beach at Apalachicola. Also, at the local Piggly-Wiggly I noticed lots of sweet potato pies laid out, along with pecan pies, of course. If I lay off the grits, maybe I will keep some room for a piece of the pecan pie, preferably with some whipped cream on top.
Earlier this week we stopped by an interesting museum in Apalach’ (as the locals refer to it). It celebrates the achievements of a local physician, John C. Gorrie, who invented the ice-making machine. He is also considered to be the father of refrigeration and air conditioning. Obviously the folks here in Florida hold Dr. Gorrie in high esteem for his dedication to cooling things off. What interests me, being that I am a chemical engineer, is how steam powered Gorrie’s ice machine. That seems very counter-intuitive, but the thermodynamics are explained nicely here by the inventor:
“If the air were highly compressed, it would heat up by the energy of compression. If this compressed air were run through metal pipes cooled with water, and if this air cooled to the water temperature was expanded down to atmospheric pressure again, very low temperatures could be obtained, even low enough to freeze water in pans in a refrigerator box.”
For a picture of what he patented in 1851 and historical background, see this Wired magazine article by Randy Alfred.
Getting back to the Thanksgiving feast this afternoon and thinking about the oysters, I suppose we will be given a choice of raw ones laid out on ice (thanks to the local inventor) or one cooked with steam. Coming from the middle of our continent, it may be too much of a stretch to eat uncooked shellfish. In fact, it makes me a bit queasy just thinking of it. Although I fancy myself an experimentalist, sometimes I must draw a line in the sand.
PS. One thing I find curious is that the oystermen (sorry ladies) still do their harvesting the old-fashioned way with tongs – see this video, for example .
New math sums digits from left to right: Does this add up as an improvement?
Posted by mark in Basic stats & math on November 22, 2009
A recent article in my local newspaper, the Stillwater Gazette, provided enlightenment on our school district’s new way of adding numbers – from left to right, rather than right to left. I might have to try this – maybe it will help me improve my accuracy when tallying checks on deposit slips. (I always hand-calculate these as a way to maintain my math muscles.)
Supposedly this left-to-right approach makes it easier for children to learn, because it goes in the same direction for processing numbers as for reading words. Here’s how it works. Let’s say that you and your spouse both collect up pennies and the first jar nets 237 cents versus 159 for the second. How much in total can be taken to the bank? The way I learned to add one first adds 7 and 9, recording 6 as the right-most digit (the ones column), and then carrying a 1 to the second column (the tens). This carrying part is where I sometimes get off, mainly due to my poor handwriting, which even I cannot always read. The new left-to-right approach eliminates a lot of carrying, but not all, I figure, as shown in the following case. Start by adding the left-most (hundreds in this case) column of numbers:
247
+159
=300
Do not forget to put in the zeroes to hold the place of what you just added. Now go to the next column to the right and add it:
= 90 (4 + 5)
And so forth until there’s no more columns:
= 16 (7 + 9)
Finally, tally up all the numbers you calculated:
300
+90
+16
406
I have a feeling that the old saying about not trying to teach an old dog new tricks might be operative for me in regard to this new math. I think I will just keep adding the old way, or admit that using a calculator or, better yet, a computerized spreadsheet for doing my deposits would be smarter. Am I shortchanging myself (pun intended)?
PS. This innovation in learning math struck a chord with my son Hank, who programs for Stat-Ease. He made me aware that “endianness” is a major issue in coding. Evidently programmers continually feud over the order in which bytes in multi-byte numbers should be stored – most-significant first (Big-Endian) or least-significant first (Little-Endian).* The “endian” terms come from Jonathan Swift who mocked the pettiness of social customs, such as which end one ought to first attack when shelling an egg.
“…the primitive way of breaking Eggs, before we eat them, was upon the larger End: But his present Majesty’s Grand-father, while he was a Boy, going to eat an Egg, and breaking it according to the ancient Practice, happened to cut one of his Fingers. Whereupon the Emperor his Father published an Edict, commanding all his Subjects, upon great Penaltys, to break the smaller End of their Eggs.”
— Jonathan Swift, Gulliver’s Travels, A Voyage to Lilliput, Chapter IV.
*For more details, see Basic concepts on Endianness.
Gambling with the devil
Posted by mark in Basic stats & math, design of experiments on November 15, 2009
In today’s “AskMarilyn” column by Marilyn vos Savant for Parade magazine she addresses a question about the game of Scrabble: Is it fair at the outset for one player to pick all seven letter-tiles rather than awaiting his turn to take one at a time? The fellow’s mother doesn’t like this. She claims that he might grab the valuable “X” before others have the chance. Follow the link for Marilyn’s answer to this issue of random (or not) sampling.
This week I did my day on DOE (design of experiments) for a biannual workshop on Lean Six Sigma sponsored by Ohio State University’s Fisher College of Business (blended with training by www.MoreSteam.com.) Early on I present a case study* on a training experiment done by a software publisher. The goal is to increase the productivity of programmers by sending them to workshop. The manager asks for volunteers from his staff of 30. Half agree to go. Upon their return from the class his annual performance rating, done subjectively on a ten-point scale, reveals a statistically significant increase due to the training. I ask you (the same as I ask my lean six sigma students): Is this fair?
“Designing an experiment is like gambling with the devil: only a random strategy can defeat all his betting systems.”
— RA Fisher
PS. I put my class to the test of whether they really “get” how to design and analyze a two-level factorial experiment by asking them to develop a long-flying and accurate paper helicopter. They use Design-Ease software, which lays out a randomized plan. However, the student tasked with dropping the ‘copters of one of the teams just grabbed all eight of their designs and jumped up the chair. I asked her if she planned to drop them all at once, or what. She told me that only one at a time would be flown – selected by intuition as the trials progressed. What an interesting sampling strategy!
PPS. Check out this paper “hella copter” developed for another statistics class (not mine).
*(Source: “Design of Experiments, A Powerful Analytical Tool” by Christopher Nachtsheim and Bradley Jones, Six Sigma Forum Magazine, August 2003.)