Tuesday, September 20, 2005

From the Top of the Atmosphere

Here is a different kind of error; I'm not at all sure where the error lies. Maybe there is none, but in that case I'm wrong to put it this way. Bottom line: the molecules in the air around you are moving about as fast as if they had just fallen from the "effective height of the atmosphere", and I think that this is true anywhere you go, on any planet. But I'm extremely unsure of this.

Definition: the "effective height of the atmosphere" is pressure/density, which at sea level is about one ton per square foot divided by about one ounce per cubic foot, which gives you somewhere near 30,000 feet. It's the height which the atmosphere would have if its density were constant. (Actually, of course, if you go up 300 feet then you've risen above 1% of the atmosphere, so the pressure goes down by 1% and [unless the temperature has dropped already] the air expands to match, so that the "effective height" will still be some 30,000 feet over your head.)

The pressure and density I mentioned may be unfamiliar, but it's easy to check them. You probably remember sea-level pressure as being 14 pounds per square inch, and one square foot is 144 square inches -- so that's about a ton. Density is not so easy; perhaps you remember that air is nearly 80% N2 with a gram-molecular weight around 28, with the residue almost all O2 of about 32, so one mole (22.4 liters, a bit more than a cubic foot) will weigh 29 grams, just about an ounce. Well, it's really about an ounce and a quarter per cubic foot. Or you can look it up somewhere -- Galileo wrote somewhere in his Dialogues Concerning Two New Sciences (that's the less famous, more geeky of his main books) that air was about 1/800th the density of water, and if you know that a cubic foot of water is 60-some pounds or about 1000 ounces, then you've got it. The effective height of the atmosphere, at least when you start from sea level, is somewhere near 30K feet. Okay? (Is it a coincidence that we're roughly locating the tropopause, the troposphere-stratosphere boundary, here? Is there a tropopause for other planets? I have no idea.) Now, what about that speed?

Thirty-five years ago, as a sophomore physics student at Nacional de Buenos Aires, I was really quite surprised to learn that air molecules have an average velocity that's higher than the speed of sound; it took a while for my intuitions to accept that this is necessarily true because, loosely speaking, when air molecules (going in all directions) carry a wave (in one direction) some of their "effort" is literally misdirected. If the speed of sound is 1000 feet per second, the average speed of the molecules is 1500. As I recall, the 3/2 is exact and drops out of some volume integral whose details I no longer recall at all, but you may have noticed that exactness doesn't worry me here anyway.

Okay, so I've claimed that the speed of the molecules, which you now know is about 1500 fps, is about what they'd get from falling 30K feet. What was that formula again? Well, constant acceleration just means V=A*T which integrates to D=0.5*A*T^2 which we solve for T to get T=SqRt(2*D/A), and now we plug that T back in to the first equation to say V=A*SqRt(2*D/A)=SqRt(2*A*D) and if A is 32 fps^2 while D is 30K, V has got to be SqRt(2,000,000) or 1,414 which is definitely close enough. So yes, it works at sea level. But is it really a coincidence, or is it a Law that the Galactic Patrol's Lensmen will come after you for violating?

Imagine a tube that goes all the way up, to the top of the atmosphere, but is only wide enough for one molecule. Imagine that it's 100% nitrogen, which shouldn't make much difference at all, except that it helps the visualization. Imagine as usual that it's an ideal gas: as each molecule bounces off the molecules above and below, energy and momentum are conserved, so that if you blink as an actual collision happens then you can't tell that the two molecules didn't simply go through each other. Okay, that should mean that the bottom molecule is moving just as fast as if it were the top molecule of a a minute ago. (The actual time T of the last paragraph is about 50 seconds.)

Problem with that tube-to-the-top-of-the-atmosphere model: it had nothing at all about 30K feet being the top of the atmosphere. The tube went to the actual "top" of the atmosphere. Another problem is that it has no way to talk about averages; everything should be at a fixed velocity relating to height. I remember this puzzle every now and then -- probably at least once a year. Sometimes I convince myself, for a minute or ten, that these two problems actually cancel out: the 30K is an effective average. Then I think I really ought to make a computational model. Then I think I really ought to do some work instead. But at least I have written my puzzlement down.

Friday, September 16, 2005

On Being The Right Size for Disaster-Handling

I'm thinking about Katrina foul-ups -- where I do tentatively think that FEMA did an unnecessarily bad job, and I do tentatively think that WalMart might be a good model for part of FEMA to follow -- and I'm feeling puzzled about the nature of centralization. I don't think that either Arnold Kling or Brad Delong are thinking seriously about WalMart, and I wish they would.

Arnold Kling, in A Challenge for Brad DeLong, claims that

Large organizations...are inherently dehumanizing...and unable to handle sudden new challenges.

Delong replies that

Shouldn't the fact that WalMart finds it more efficient to be a bureaucracy of 1.5 million people--rather than to split itself up into 15,000 companies of a hundred employees each--make Arnold Kling a little hesitant in his declarations that FEMA was bound to foul up this badly no matter what? Serious thoughts about when wants to use market and when one wants to use command-and-large-organizations--and how one then controls command-and-bureaucracy--would be very welcome here.

Kling, apparently accepting the characterization of WalMart as "a bureaucracy of 1.5 million people", responds that

The fact that Wal-Mart is not highly decentralized reflects the importance of economies of scale in its logistics capability.

I wonder if either Kling or Delong know that WalMart is being sued, in part, for being too heavily decentralized? Read Always Low Prices -- Always: WM vs. Class Actions

Central to the plaintiffs' case is the contention that Wal-Mart is a heavily decentralized company, in which managers are given wide latitude to make hiring, pay and promotion decisions. This, the lawyers argue, is a bad thing, because it leaves too much discretion in the hands of store managers, who can thus be influenced by their own negative stereotypes. Under this scenario, decentralization in management, which has been one of the core productivity-boosting principles of American business in the last two decades, becomes something that companies must avoid or limit.

WalMart has a shared database, which is centralized. It has a shared "culture", which WalMart works hard at by, e.g., moving managers around. It also seems to have central directives, which must be obeyed. Nonetheless, it appears to have achieved an interesting kind of decentralization. It isn't split into Delong's "15,000 companies of 100 employees each", but it is split into close to 5000 units of about 150 each, some hundreds of supercenters of about 350 each, and then of course the supporting divisions from warehousing and trucking to database management.

In Tom Peter's Pursuit of Excellence, the section on "Smallness" begins on page 270. Beginning on page 271 we see a conversation about the need to "Divide it up", then

The point of smallness is that it induces manageability and, above all, commitment. A manager really can understand something that is small and in which one central discipline prevails...More important, even in institutions that employ hundreds of thousands of people, if the divisions are small enough, ... the individual still counts and can stand out. ... The lion's share of the top performers keep their division size between $50 and $100 million, with a maximum of 1000 employees each. Moreover, they grant their divisions extraordinary independence...

As I understand it, each WalMart unit has a limited function, and has the objective of achieving that function at lowest cost. Some decisions take place within units located in Bentonville, and others don't. Each unit is small enough so that a unit manager can know everybody, so that "the individual still counts and can stand out" -- so he has a role to fill in achieving the objective of his unit. So he can be fired (or possibly given a second or third chance), in case of failure in filling his role.

Maybe FEMA, or part of FEMA, can indeed be like that, with a central database of trucks, buses, trains, boats, planes and people, to identify and locate resources when a hurricane threatens or the New Madrid lets go or flying saucers come down and start zapping skyscrapers. Would you volunteer your minivan? Then you should be in the database. (And is it AWD, and are you an experienced snow driver?) Would you volunteer a room or two in your house? ditto. And so on. My rural village is unlikely to be evacuated, but has a lot of resources (e.g., schoolbuses) which could be predesignated and called upon when we finally have to evacuate NYC. Central commands slow things down, I believe, and should rarely be invoked except to initiate or correct. (I will try to describe the system I'm visualizing, but not today.)

It would be very interesting to see somebody try to organize FEMA that way. I don't think Bush tried (though as I understand it, he quite correctly resisted the folding of FEMA into DHS). There should, of course, be some specific unit of FEMA which was responsible for checking the New Orleans evacuation plan, and which should have noticed when the city government started preparing the "you're on your own" DVDs this summer. I think of that as criminal. I think of the Louisiana failure to pre-allocate some of those 21,000 registered buses (for evacuation of the coast) as criminal. I think of FEMA's failure to notice as being...well, maybe not criminal. But definitely not good, and quite possibly attributable to a lack of focus.

UPDATE: it's perfectly possible that FEMA, at whatever level, did notice the city's you're-on-your-own plans and said they were okay; I would at present consider that to be criminal. More central to my own thinking, though, is the WalMart class action suit.

The class action suit explains at length that WalMart is highly centralized in terms of data-tracking, and in terms of a uniform culture, and in terms of some specific policies decided at the highest level. However, this is largely background, explaining why a class action suit is legitimate. The discrimination complaint itself has to do with payroll and promotion policies which are not centrally decided.

In sum, Wal-Mart deliberately grants its managers broad discretion at critical junctures in making compensation decisions for employees in the field. ... For promotions above department manager Wal-Mart has a very subjective process [that has systematically disadvantaged women]... Wal-Mart also allows store managers to apply their own unwritten criteria when selecting candidates. Store Manager, Art Mireles, for example, testified that he relied on factors such as teamwork, ethics, integrity and the ability to get along with others.
How, then, does WalMart control the store manager whose subjective judgement is given so much power? The class action suit explains how it works:
the major part of store manager's compensation is tied to store profitability.
Well, sure.

I have no desire to defend or attack WalMart, but it seems to me that it is not useful to describe it as "a bureaucracy of 1.5 million people." It is a product of evolution, of cumulative selection on several levels simultaneously, in which WalMart, Costco, Target, KMart, Home Depot, Ames, and on and on are constantly competing for the same dollars; in which each WalMart store competes for resources with other WalMart stores, each WalMart manager competes for resources with other WalMart managers, and so on. The result is an extremely focused collection of entities providing a highly efficient path from supplier to customer -- but not the most efficient path, because there is no such thing. The struggle will continue, and I expect that WalMart will eventually go under.

Can FEMA, or part of FEMA, be structured that way? Maybe it could be, but I don't think that anyone has tried.

Monday, September 12, 2005

The Dwarves are for the Dwarves

2005-09-11; an ordinary Sunday. I walk half a mile to the coffee shop, with my eight-year-old and her doll stroller, containing "Pink Doll" who has been going to the coffee shop for eight years now. We come back.

Later, we go with Mama (and the doll stroller, now containing "Sarah", who is only about five) to the mall, then to the food court (pizza for Daddy and daughter, Chinese for Mama, Sarah's not hungry), and to Sears ("Two Out of Three American Households Have Sears Appliances") where we get a winter jacket with some growing room. Then to Bed, Bath and Beyond, because Mama is tired of plastic cups in the bathroom, and we get some stainless steel cups instead. Then next door to BB and B is Barnes and Noble, where it seems to be sequel and prequel day: two of the sequels to Misty of Chincoteague, a sequel to The Best Christmas Pageant Ever, and I guess the first two American Girl books about the life of "Addy", a doll's character about whom my girl already has two later books.

(All the American Girl dolls are given biographies with historical settings; Addy is born a slave who escapes near the beginning of the Civil War. I have told my daughter that my grandfather, as a little boy, had a nanny who'd been born a slave, and who had come up from North (?) Carolina to Baltimore to get a job, and was saving up to bring her husband to join her. He told me about her taking him down to the docks to cheer the troops headed for the Spanish-American War, which he could barely remember, but he knew she thought it all had something to do with spreading freedom.)

On the way there, and on the way back, we're listening to Narnia on tape: we've come to The Last Battle, narrated by Patrick Stewart, and it's strange to hear the voice of Captain Picard narrating the glorious deaths of the good guys. Given where we stopped, I don't think my daughter quite realizes that they're all dead (and very happily so, except perhaps for the servants of the evil god Tash who have been taken away, and for the dwarves who refuse to be taken in by anybody, being totally focussed on their own concerns. They, too, get to Heaven, after a fashion, but they don't notice. They can't. The reality they're in is simply not within the scope of their imagination. The dwarves are for the dwarves.)

And when we get home? Well, we have a pretty traditional family setup where it's perfectly clear who decides when a carpet has become too decrepit and stained from years of use by our elder kids; and when she comes to that decision, it's also perfectly clear whose job it is to take up the carpet, the padding, and the staples and assorted hardware that held everything down, and get it all to the side of the road. (Can I lift it? Not really. But I can get it to the side of the road.) But it's also clear who cleans up the mess thereafter, and I'm not complaining. I'm just awaiting the next decision with some trepidation.

But it's not really an ordinary Sunday. A little because of the Katrina donations "proudly accepted" by Sears (BB and B just points you to the Red Cross), and a little because of a letter I'd missed about a school that we've indirectly sent money to:

All students parent are gardner. They live in Thailand but they have their gardners in Karen state. They have to work in fear, in addition to, they also have to face a big problem as rats are amputate the rice. For this reason, they haven't had enough food for them to eat. As the parents are have to deal with the problem, their children are have to deal with the problem as well. In this way, in future, students together with their parents are definitely will be facing the problem.
But mostly, it's not ordinary because it's 9/11. Even without the 9/11 photos on the wall of the coffee shop, it's not ordinary. Maybe it's getting to be an ordinary day for most people, but not for me. Not yet. I keep thinking -- how could I have been surprised? How could I have failed to see something of the sort -- many things of the sort -- on the way? 9/11 is my day for feeling stupid, and for being frightened of my own stupidity; I don't know why other people don't seem to feel this way.

I'd noticed the World Trade Center bombing in 1993, of course. I knew in a general sort of way about the 1994 attempt to blow up the Eiffel Tower with Flight 8969. I knew in a general sort of way about the 1995 Bojinka plan to blow up multiple airliners. But I still have email from 1996 in which I agreed with an e-friend that airline security was not merely a joke but an unjustifiable intrusion. What was I thinking?

I knew that feeble US responses had been encouraging bad guys since before I went to the University of Delaware to interview for an Asst Prof of CS job, on April 25, 1980. I knew that the US was and is giving many billions per year in oil money, some of which goes to feed fanatics who really believe that they must and shall rule.

I was busy, in my own part of the world. I had lots of things to think about, all through the 80s and 90s. I still do. I worry now -- what obvious things am I not seeing because they do not fit within the scope of my imagination?

The Dwarves are for the Dwarves.

Friday, September 09, 2005

Katrina Logistics Puzzlement

I don't understand the New Orleans/Gulf Coast hurricane evacuation planning or the subsequent criticism, because neither seems to talk about the use of buses from all over. Drudge reported on the Louisiana evacuation plan based on buses, as of course it had to be; many bloggers have talked about the Nagin Memorial Motor Pool and how thousands could have been saved by using those buses; others, especially at Countercolumn, have talked about the logistical limits of those buses, how they couldn't have saved everybody; but those aren't all the buses available. I'd have expected a process more or less like this:

  1. There are people living below sea level.
  2. They're in a hurricane zone.
  3. It will be flooded.
  4. So we tell them: If you don't get out, you'll die.
  5. Oops, 100,000+ of them are poor, with no cars.
  6. Okay, they need to be bused out.
  7. Oops, the City of New Orleans has less than a thousand buses. (Besides, we need to evacuate many outside the city, too.)
  8. Okay, the State of Louisiana has 4.5 million people and certainly has several thousand buses. (I don't know how many. In 2000, the US had some 53 million school-age kids with 48 million enrolled in school -- about 17% of the population. That's probably pretty close to Louisiana's percentage, though New Orleans school-age kids seems to be more like 20% of the population. I presume that a reasonably large fraction of these ride buses.)
  9. Other states have buses too.
  10. Hey, let's plan to bring in enough buses! (Is this rocket science?)
  11. Oops, it takes a while to bring in buses; Google Maps says that from the far corner of Louisiana you might need 8 hours, from the far corners of Arkansas you might need 13. You probably don't need those, but if you do --
  12. when we get to the 60-hour mark, they (enough of them) start driving.
  13. If all goes well, they will drive back. Empty. (Yes, this costs money. Maybe over a thousand dollars per bus per false alarm -- several million dollars total. Wow.)
  14. If not, they drive back full. To schools, churches, whatever.
  15. Oops, we found in other evacuations, some people won't go without their pets.
  16. Okay, we also have trucks, uncomfortable but available: give your dog a sedative, get on, GO!
  17. Oops, there may not be enough fuel for all these extra vehicles and the cars headed out.
  18. Okay, we also have fuel trucks, going down at roughly the same time.

There will naturally be other Oopses, mostly having to do with coordination. I would assume that the several hundred buses of the city being evacuated would be used to ferry people to the highway, and the couple-of-thousand buses going away from it would pick them up there. (This could also make people more willing to go, if they get to choose from a limited set of destinations, especially prearranged destinations.) I would assume that every bus can have a cell phone which talks to a database via text messaging to an email address, and every bus probably has a pair of National Guardsmen (one of whom is good at text messaging) in addition to any Guardsmen they may have to deploy at the end point or even at gas stations on the way. So on the drive, everybody gets on the list.

Cell phone problems? Remember, we are doing this coordination before wind takes out the cell phone towers...and text messaging is low-bandwidth, generally. Actually, the post-disaster coordination can still depend on cells, if the first thing the helicopters from the Bataan do (long before the levees break) is to set up portable cell towers. From anchored balloons, if they have to.

Traffic problems? Yes, though the buses are a small addition to the many thousands of cars on the way, so the inbound lanes that became outbound lanes would be restricted to buses and trucks and cars carrying more than -- oh, I don't know, maybe more than 5 people. Lots of problems, but what I really don't understand is why nobody seems to be talking about those other buses. I'm missing something.

UPDATE: instapundit points to Louisiana Fast Facts 2000 which reports 21,000 registered buses at that time. That ought to be enough for a million or so riders, and there were many more cars than 21,000 in the evacuation, so I really see no reason why Louisiana shouldn't have been able to evacuate all the carless people from New Orleans, and from any other parts of the coast that might have needed it.

Sunday, September 04, 2005

Political Errors

In 1968, as a high-school student, I gave a little speech accepting an "American History Award" from the American Women's Society of Bogotá, Colombia. (I think I still have the plaque.) I predicted the extinction of homo sapiens, to take place by the year 2000. (Mom made me write an apology, but not a retraction.)

If this happened, I guess I missed it. But I was very sincere at the time, and I still think it could have happened. We were lucky.

That was probably my worst political-prediction error, but I think my worst political error, from the same period, was one of misclassification. You see, I thought Vietnam was an unjust war; I thought we were the bad guys.

Why? I had several kinds of reason, starting with our opposition to free elections because, as wikipedia quotes Eisenhower, possibly 80 per cent of the population would have voted for the communist Ho Chi Minh. On a more personal level, Norman Morrison was my First-Day School teacher's husband at the time that he immolated himself on the Pentagon steps. And in between, my father and grandfather were non-pacifist Quakers who were proud of service in their respective World Wars, but who opposed Vietnam.

So when I turned 18 and registered in Buenos Aires, just a couple of months after Kent State, I was walking around making speeches to myself about being a non-pacifistic conscientious objector, unwilling to pretend a religious objection to all war but willing to go to jail rather than serve -- and I totally blanked out on the fact that my having been diagnosed as an epileptic (incorrectly, I learned years later) made me an automatic 4F. This was embarrassing, but did not affect my views of Vietnam as an unjust war.

But then came the boat people. When a small country finishes a war and the good guys win, you don't expect a million or two of its people who have stuck it out through that war to risk their lives running away from the peace. If a million or two of its people do risk their lives running away, then you have to question your assumptions. The good guys did not win. Maybe it was an ill-thought war (or maybe not), maybe we should have stayed out (or maybe not), maybe our defeat was inevitable (or maybe not). But the guys who won were not the good guys; the boat people (primarily) convinced me of that. If I had foreseen the boat people, I would have volunteered to serve in Vietnam. (And I'd have been rejected.)

This is an extremely tentative blog, in which I expect to put some of my past mistakes on record and add new ones. My mistakes as a programmer and author tend to relate to Java, Javascript, XSL, and XML/XHTML, but I may also post about mistakes in politics, parenting, house renovation, driving in upstate New York, and so on.

Let me begin by admitting that back in the very early 1990s, as an asst. prof. of Computer Science at Colgate University, I was a lurker on a discussion list about the dawn of the WWW, with frequent posts by some guy named Tim Berners-Lee. And the NSF had given me a grant for NeXT cubes, which were running his first browser...and my desktop PC was linux.colgate.edu. Very forward-looking, yes? Well, actually no. I dropped off that WWW list because even though I liked the idea, I didn't see how it would get the critical mass of users I thought it needed. And I told my students in Operating Systems that Linux was filling a temporary need but it wasn't going anywhere. After all, I was teaching with Tanenbaum's book (the earlier edition) and everybody in my world knows his view of Linux.

So if you expect me to say anything true, even in areas where you might think that I ought to be an expert, I am hereby warning you that this is a totally irrational expectation.