Wednesday, July 27, 2011

Bad Management or Excellent Engineering?

One client that we have at Aspen Research has a product that they first started manufacturing 50 years ago. Yes, 50 years ago, and they still make it and sell it. [1] There is however, a fly in the ointment and a colleague and I are in disagreement about how to interpret the situation surrounding that fly.

Over the past 50 years, the production yields have gradually fallen to the point that yields are just a few percent. I see that as a total failure of management, that they would let things slip away like that for so long, a perfect example of the boiled frogs analogy [2]. My colleague on the other hand, thinks the story is an example of engineering excellence: the original development of the product was completed so well that it took 50 years of lesser competence to destroy what was originally there.

What do you think?

[1] I'd love to tell you what it is, but confidentiality reigns here.

[2] The "boiled frogs" analogy is that if you take a frog and put him in a pot of boiling water, he will immediately jump out and save its life, but if you put him in a pot of cold water and turn on the heat, the discomfort for the frog gradually increases but the slow increases in discomfort are never enough to cause him to jump out. He ends up being boiled. I have no idea if frogs would actually behave like this, but I find the story does provide a useful analogy regardless. There are way too many examples of situations in business and life where conditions gradually worsen to the point that if you were put in it anew, you would immediately leave, but because the conditions worsened at a slow rate, you tolerated them.

Tuesday, July 26, 2011

Plastic is Forever (Shhh! Don't tell the Art Curators)

"Plastic is Forever" has become a rallying cry for certain environmentalists. The ironic situation is that they have set up an art show made from plastics retrieved at beaches.

I said ironic [*], as that truly is the case. Art and museum curators, people who want to keep plastic in pristine condition, have known for quite some time that plastics are quite prone to oxidation and degradation. Sarah Everts, on her "Artful Science" blog had a recent posting on the matter. Having helped numerous clients with degradation and oxidation issues in their products, I was well aware of the relentless degradation, but I didn't know that cellulose acetate was able to wreak havoc on other materials in its immediate vicinity.

Imagine if this "Plastic is Forever" art show sticks around for 30 years or so: they will be in the uncomfortable position of having to explain why their art is degrading.

[*] An additional irony of sorts: the show is at Bainbridge Performing Arts, abbreviated on their webpage as "BPA".

Monday, July 25, 2011

Jello Comparisons

Comparisons to Jello are rampant in the news lately. First, in the ongoing negotiations between Congress and the White House, Speaker Boehner said
"Dealing with them the last couple months has been like dealing with Jell-O, Boehner said. 'Some days it's firmer than others. Sometimes it's like they've left it out over night.'"
That at least is a proper characterization of Jello. For a dubious comparison, consider this comparison made when discussing the negotiations between the NFL and the team owners. A punter (coincidentally who plays for the local Minnesota Vikings) had shot his mouth off (aka Tweeted) about the situation and was taken to task for the little contributions that a punter makes to the team.
"But perhaps the moment most indicative of the separation between punter and football player is when one of his punts is returned for a touchdown. The punter, the nominal last line of defense, appears to be an invertebrate on a sheet of ice as he squirms into a position to make the tackle. His eyes widen and he splays his arms out to the side as if to embrace a giant teddy bear. The returner, with a quick head nod, sends the punter blindly lurching to the wrong side, into a Jell-O-like pile of his own shortcomings."
(emphasis added) So what exactly is a Jello-like pile of shortcomings?

It's not often that I praise politicians, but in this case, Boehner certainly showed a higher understanding of Jello rheology than a sportwriter.

Friday, July 22, 2011

The Heat Index and Jenson's Inequality

I've mentioned Jensen's Inequality before, which deals with the average output of a nonlinear function. If the function increases nonlinearly with increases in the input, then the average output will be greater than the output of the average input. How about a real world example? In chemical reactions, the reaction rate increases in a nonlinear fashion with temperature. So if you run a reaction for a time period at T1 and then later for the same time at T2 (so that the avereage temperature for the reaction is Tavg = (T1 + T2)/2), the total extent of the reaction will actually be greater than if the reaction had been run strictly at Tavg. The reaction ran much faster at the higher temperature, more than enough to compensate for the slowness at the lower temperature.

I realized another use for Jensen's inequality while sweltering through the recent heat and humidity wave that started in the Midwest and is now blanketing the East coast. This was actually the result of a lively discussion on the Minnesota Forecaster's blog on the impact of a wind on the heat index.

The heat index is based on a remarkably long set of factors. You can read the original research article (open access) if you like - it's a pretty straight forward engineering analysis. I (and you) can certainly suggest other assumptions to be made, but realize that the calculations are all laid out for you, so feel free to recalculate out your own results. The biggest issue I had with the original report was that it was assumed that there was a constant wind speed of 5.6 mph.

Heat transfer from forced convection (wind) is nonlinear (I think you can see now where I am going with this, huh), in this case varying with the 0.3 power - a decreasing exponent. In this case then, Jensen's inequality is reversed. If the wind blows for a fixed time at speed v1 and the later at v2, the cooling effect will be worse than if it had just blown at vavg. I've never felt a constant wind speed so this is actually an important result. The fact that the wind is assumed at a non-zero constant actually understates the heat index, especially in the lack of wind. The slightest breeze is more important than any incremental increase, something we all appreciated on some of those near windless days.

Thursday, July 21, 2011

A Slippery Slope Indeed

Plastics News is reporting this week that the California Supreme Court has allowed the city of Manhattan Beach to ban the use of single-use plastic carryout bags. But part of the rationale suggests a very challenging future for broader bans in California.

One of the challenges to the ban was that an Environmental Impact Review had not been completed. The court had a interesting take on that issue however:
"First, even though the court said no environmental impact report (EIR) is needed in the Manhattan Beach case because “substantial evidence and common sense support the city’s determination that its ordinance would have no significant environmental effect,” the court also said that its analysis of whether an EIR is necessary to enact a plastic bag ban would vary under different circumstances.

“The analysis would be different for a ban on plastic bags by a larger governmental body [as it] might precipitate a significant increase in paper bag consumption,” said the court.

In addition, the court said “cumulative impacts [of bans] should not be allowed to escape review when they arise from a series of small-scale projects.”"
Now that could get to be a very difficult question to answer in the future: how big is too big? And also, how many is too many?

The only certainty from this decision? Job security for lawyers.

Tuesday, July 19, 2011

Making a Mess of Good Research

You may have read my post last month about a research paper that found that degradable polymers in landfills generated methane, a potent greenhouse gas. While I did have a few quibbles about the research, I generally thought it was a good paper, one in which the researchers did not overgeneralize their results or have a bias towards a certain outcome.

Boy was I wrong.

One of the researchers has an opinion piece in this week's Plastic News [1] in which he completely overstates his research results, does not understand the reaction of others to his research, and isn't cognizant of his own biases. Let's start with one of the most innocuous statements
"The foundation of this research is a life-cycle accounting of the greenhouse gas (GHG) emissions associated with discarding waste in both national-average and state-of-the-art landfills. A state-of-the-art landfill collects the generated methane and beneficially uses it. Only an estimated 35 percent of waste is discarded in state-of-the-art landfills, while about 31 percent of waste is in landfills without any gas collection. The rest is in landfills that collect and flare the gas.

The results of this research show that there are significant benefits to collecting and beneficially using landfill gas. Disposing of mixed municipal solid waste in a state-of-the-art landfill is carbon negative, but disposing of similar waste in a national-average landfill leads to positive GHG emissions. The results of this analysis also show that the more degradable a material is, the greater the GHG emissions it generates when disposed in a landfill. The best material to have in a landfill, from a GHG emissions standpoint, is one that does not degrade at all."
I'm fine with every line in that except the second to last one: "The results of this analysis also show that the more degradable a material is, the greater the GHG emissions it generates when disposed in a landfill."

While this certainly was true as a trend in what they found in their research, the data and analysis is nowhere even hinting that such a result is universal for all materials. A trend gathered from the few select materials that they studied is not what is used to make predictions - the data they have is far, far short of what is needed to suggest that it is a universal law. It certainly can be used to make a hypothesis and then further test that hypothesis, but it is not a result, a demonstrable truth, and for the author to make that statement now is unnerving.
"Numerous articles and comments written by anti-environmentalists have tried to use the results to portray environmentalists and environmentalism as naive and/or misguided. This argument is nonsensical when made by those who deny anthropogenic climate change. This research is meaningless if one does not first accept basic climate science."
The last 2 sentences have me completely floored. The results of the research are meaningless depending on what you think about global warming? So is he saying that, if you believe in global warming (as the author does) you get one result, but if you don’t, then you get another result? Or is it more along the lines that evolutionary research results are meaningless to creationists? Either way, I don't understand it.
"The purpose of the research is to allow us to more effectively mitigate GHG emissions by making informed decisions."
There you have it, an admission that this research was undertaken to prove a certain point rather than explore an unknown or test a hypothesis. The author has a bias that he was looking to support. No wonder he calls the headline "Biodegradable products are often worse for the planet" as "reckless". I don't see that headline as such.

Why the author decides to swing so widely from research supported conclusions to wildly broad assertions is beyond me. And for him to somehow try to say that he is the final arbiter of what the research means is even worse. As I stated at the beginning, I read the paper and thought that it was a nice piece of research. I still do. I just can't believe the way it is being misrepresented by its own author, all while attempting to state that others are misrepresenting it.

[1] Don Loepp first raised this issue in his Plastics News blog last week. I didn't realize that the opinion piece he quoted was being published on paper.

[2] I'm reminded of an inventor filing for a patent with overly broad claims that end up getting greatly narrowed at the patent office. As soon as the patent issues however, the inventor starts making the over broad claims again

Monday, July 18, 2011

How to Not Explain the Deborah Number

While I normally find XKCD to be entertaining, I thought today's cartoon was a horrible way to explain the Deborah Number:

The explanation is not wrong per se, but it's just too long winded in getting to the point, and misses the perspective that rheologist, geologists,evolutionary biologists, cosmologists and other have: that the time scale of a human being is too short of a time interval to be an appropriate unit for observing the natural world.

Friday, July 15, 2011

A New Polymer Blog

Or maybe this is more like saying that someone is expecting.

Tom Phillips will be starting school in the fall, pursuing a doctorate at the Plastic Electronics Doctoral Training Centre, and will be blogging about his experiences. Since I'm not expecting much polymer discussions until he actually starts his studies, this might be more like what I said above - we are expecting a live birth sometime soon - rather than a formal birth announcement. Nonetheless, we might be surprised to feel the baby kick sometime too.

(Poor Tom. All excited about starting his blog and I go around comparing him to a pregnant woman. Sorry - I will be nicer in the future.)

Wednesday, July 13, 2011

Just the same, only really different

One of the baseball players in town here, Justin Morneau is from Canada, a country normally associated with producing hockey players, not baseball players. He has radio commercial in which he makes fun of that stereotype and himself by saying he thinks baseball is just like hockey, only really different.

That's how I see the rheology of granular materials - they're just like fluids, only really different. We saw a few weeks back that under enough stress, theoretically all granular media can act like Bingham fluids with a yield stress and terminal velocity for falling objects, which is just like a fluid. Similarly, ATA Scientific has a list of simple results from the rheology of particles which is worth a look. Consider the first two examples from their list
"1. Decrease particle size and viscosity will increase.
In a constant volume fraction, the number of particles will increase when particle size decreases. As a result of this, the number of interactions between particles increases as well, leading to an overall increase in viscosity (the resistance to force that causes flow). The effect is more common at low shear rates, as a particle-particle interaction is a weak force.

2. Increase particle size and viscosity will decrease
Keeping the previous point in mind, it stands to reason that if you were to increase the particle size, this would lead to a lower amount of particle-particle interactions, resulting in a decrease in viscosity. As before, this effect is most common at low shear rates."
Nice simple explanations which I always like. Again, look at the rest of the list (but maybe after you finish my post).

The one trend I noticed in the list, and that you even see in the example I gave, is that particle rheology examples always seem to have far more restrictions and assumptions than fluid mechanic examples do. "...under enough stress...", " a constant volume fraction..." etc. If you ignore those prescripts, then you start finding strong divergences from fluid mechanics.

And boy are there plenty of examples of divergences, whether it's the Brazil nut effect, bridging, rat holing and a whole host of other examples, particle rheology is just like fluid mechanics, only really different.

Tuesday, July 12, 2011

Art with a Rheological Influence

Almost by total accident, I ran across the artwork of Mike Solomon, a New York-based artist who appears to work with netting and resins to create sculptures with some beautiful flow in them. Consider this one, called "Panta rhei": Somehow Mike has brushed up against rheologists, as he doesn't just stop with Panta rhei, but also has another rheology-inspired sculpture entitled "The Deborah Number":
His website has many more pictures of his art, most of which do not have a rheological title. Please click over there and have a look. In the mean time, I'm contacting Mike to find out about how he became so rheological.

Wednesday, July 06, 2011

"Scientists Develop Bioplastic"

Just another typical headline, right? Oh no it's not - read the entire article and then decide.


Scientists in Point Lees University, Keele, have developed a new plastic that is biodegradable, made from renewable sources and versatile.

"This is the ultimate plastic," said Teresa Plant, lead materials science officer at Point Lees's chemistry lab. "We can make it as hard or as pliable as we like. We imagine that pretty soon all plastics we use from sandwich wrappers to car parts will be made of this plastic."

Ligneous Plastic, as it has been termed, can be made using organic waste material, making it another ideal use of the waste that society produces in copious amounts.

"Ligneous plastic is made using a proprietary system," said Plant. "People can rest assured though, we don't have to use harsh chemicals to extract the plastic, nor do we use excessive amounts of energy. We can almost make it by hand."

By varying amounts of a secondary plastic that is produced alongside Ligneous Plastic, celluloid, the properties of Ligneous Plastic can be adjusted to make it more or less pliable.

"The only thing we've not been able to produce," said Plant, "is a transparent plastic. Even with mostly celluloid and only added ligneous plastic for strength, we couldn't make it completely see-through so we'll be carrying on looking."

"So far, they've been keeping this close to their chests," said Paul Looter, an environmentalist with Greenpeas. "I'd like to see more than words. I'd like to see the product and the manufacturing process to see if it is as green as they say."

In response, Plant produced a plank of the new plastic.

"It's wood," said Looter.

"It's like wood," said Plant. "It grows on trees and we can make any shape we like with it. It's definitely plastic though. This one also smells of pine."

Tuesday, July 05, 2011

Bicycle Racing is a Team Sport...

and here's proof:Source
This photo was take at the end of the third stage. The guy in white, front-and-center, (Tyler Farrar) is about the cross the finishing line and win the stage. That's fine and nice, but my focus today is elsewhere. Who can you see with a fist in the air celebrating the victory? A teammate, Julian Dean, who helped lead him up to the line, keeping Farrar out of the wind. In doing so, Dean destroyed his own chances to win.

But look further again [*]. Right behind Farrar is Thor Hushvold, another teammate of Farrar, who, while WEARING THE YELLOW JERSEY AS OVERALL RACE LEADER also helped lead out his teammate. You can't see it here, but the TV camera yesterday caught it perfectly that Hushvold too was also celebrating Farrar's win before Farrar did. By the way, Hushvold normally wears another jersey all year long unless he's wearing the yellow jersey - it's call the WORLD CHAMPION'S JERSEY.

So let's put this all together. The Cervelo team decided that Tyler Farrar had the best chance to win that day, so everybody, including the World Champion and Yellow Jersey all gave up their chances to win and helped Tyler Farrar win.

Bicycle Racing is a team sport.

[*] Isn't this beginning to remind you of the picture analysis I discussed yesterday?

How to Torture a Chemist

Given yesterday was a national Holiday (Independence Day), it was a 3-day weekend for us and the lab in a complete shutdown, leading to my pain.

Friday after work I was enjoying a wonderful Lithuanian beer with my wife when a thought hit me, a creative breakthrough about how to tackle a new project at work. I knew with a little experimentation it would work. The problem? The agony? I had to play with the idea in my mind all 3 days, knowing that if I went into the lab, I'd be there alone, and given what happened last weekend to a chemistry student working in their lab alone, I wasn't going to chance it. No, the mental anguish was mine and mine alone to bear, something only a chemist could understand.

Finally [*], it's off to the lab! The pain is over! I've been set free!

[*] Salt was poured on the wounds by the IT department. They decided that we all needed a new service pack installed for Windows, and that didn't go smoothly. After 3 hours, the install timed out and I was finally granted access to the computer and the past data I needed.

Monday, July 04, 2011

One Pinpoint of Light

Since today is the Fourth of July (Independence Day in the US), a picture of stars is perfectly appropriate. This one is courtesy of the Astronomy Picture of the Day website, a site I highly recommend. Most pictures are of jaw dropping nebula and such, but this one from Friday actually shows an experimental observation, and how one little dot of light changed humanities entire outlook on the universe.
The famed astronomer Edwin Hubble (namesake of the Hubble Space Telescope) was looking at a couple of images of the Andromeda Galaxy. Some of the small pinpoints of light were nova that faded over time, and these are marked in the black-and-white photo in the lower right by the letter "n". However, one of the suspected nova, relabeled as "VAR!" turned out to not be nova at all, but a variable star (one's who intensity changed over time) and not just any variable start, but of a particular class called cepheids. These stars have a intensity that is a function of periodicity of the variability. If you know the period of the variability, you know how bright the star at a standard distance, and since you can measure how bright the star is on earth, you can then calculate the true distance of the star.

So from this small prick of light, it was then possible to determine the distance to the Andromeda galaxy. This was extremely important as it showed for the first time that the galaxy was outside of our galaxy, and this then led to the idea that the universe is filled with galaxies. All that from a small pinpoint of light.

Astronomy has always fascinated me because of the difficulty of making the measurements. No one can go to a star or a galaxy to observe them first hand - we are stuck on the ground in a little planet that doesn't seem to be remarkable in any way, looking at little deviations like this that most of us would never even think are significant at all. And so astronomers have to compensate for this with cleverness and creativity.

As polymer scientists and engineers, can't we do the same? Instead of constantly relying on all the (comfortable) trappings of our instruments, what can we find out if were to do some boring grunt work, looking at for a tiny little datum somewhere in a massive field that could change our entire outlook?

Friday, July 01, 2011

Quicksand! It's Everywhere!

I remember as a youngster being terrorized by black-and-white movie scenes where a jungle explorer walks into quicksand and disappears forever, leaving only his pith hat on top of the sand for others to find. We now know that quicksand is relatively uncommon and isn't that dangerous anyway since you would only sink until Archimedes' Law kicks and you end up floating in the mess.

However, a new report (subscription required - an independent review) in Physics Review Letters suggests that the rather unusual rheology of quicksand might be much more common than we think. Before I completely scare the bejeebers out of you, let me explain the report.

The dominant thought pattern regarding granular media, and in this case, dry granular media, is that objects falling into will eventually come to a stop because the energy of the falling body is absorbed by the inefficiencies of the media (friction). It was discovered however, that that is not always true. The researchers filled a ping-pong ball with steel, dropped it in a 20 foot tube of polystyrene beads and found that not only did the ball not stop falling, it eventually fell at a steady rate - a terminal velocity. Since the existence of a terminal velocity meant that the forces on the ball were balanced, the ball would never stop falling and should continue downward at that same speed forever.

Theoretical analysis supported this and suggests that even ordinary sand could fit the criteria - meaning that if you were walking on the beach, you could end up falling through the sand forever never to be seen again. Before you panic and decide to take your chances with the sharks and not the sand next time you are at the ocean, there is only one catch to this: for a ping-pong ball to fall into dry sand, it would need a density of 400 g/cm3, which is about 20 times higher than the densest metals on earth (osmium, 22.5 g/cm3.)

It is also interesting that this result is independent of the initial velocity, which sort of plays against intuition, but then again when you think about it, bullets are stopped by sand in very short order.