The energy cost of airplanes, trains, and buses

I’ve come to conclude that airplane travel makes a lot more sense than high-speed trains. Consider the marginal energy cost of a 90kg (200 lb) person getting on a 737-800, the most commonly flown commercial jet in US service. For this plane, the ratio of lift/drag at cruise speed is 19, suggesting an average value of 15 or so for a 1 hr trip when you include take-off and landing. The energy cost of his trip is related to the cost of jet fuel, about \$3.20/gallon, or about \$1/kg. The heat energy content of jet fuel is 44 MJ/kg. Assuming an average engine efficiency of 21%, we calculate a motive-energy cost of 1.1 x 10-7 \$/J. The amount of energy per mile is just force times distance. Force is the person’s weight in (in Newtons) divided by 15, the lift/drag ratio. The energy use 1609 m (1 mile) is 90*9.8*1609/15 = 94,600 J. Multiplying by the \$-per-J we find the marginal cost is 1¢ per mile: virtually nothing compared to driving.

The Wright brothers testing their gliders in 1901 (left) and 1902 (right). The angle of the tether reflects a dramatic improvement in lift-to-drag ratio; the marginal cost per mile is inversely proportional to the lift-to-drag ratio.

The marginal cost of 1¢/passenger mile explains why airplanes offer crazy-low, fares to fill seats. But this is just the marginal cost. The average energy cost is higher since it includes the weight of the plane. On a reasonably full 737 flight, the passengers and luggage  weigh about 1/4 as much as the plane and its fuel. Effectively, each passenger weighs 800 lbs, suggesting a 4¢/mile energy cost, or \$20 of energy per passenger for the 500 mile flight from Detroit to NY. Though the fuel rate of burn is high, about 5000 lbs/hr, the mpg is high because of the high speed and the high number of passengers. The 737 gets somewhat more than 80 passenger miles per gallon, far less than the typical person driving — and the 747 does better yet.

The average passengers must pay more than \$20 for a flight to cover wages, capital, interest, profit, taxes, and landing fees. Still, one can see how discount airlines could make money if they have a good deal with a hub airport, one that allows them low landing fees and allows them to buy fuel at near cost.

Compare this to any proposed super-fast or Mag-lev train. Over any significant distance, the plane will be cheaper, faster, and as energy-efficient. Current US passenger trains, when fairly full, boast a fuel economy of 200 passenger miles per gallon, but they are rarely full. Currently, they take some 15 hours to go Detroit to NY, in part because they go slow, and in part because they go via longer routes, visiting Toronto and Montreal in this case, with many stops along the way. With this long route, even if the train got 150 passenger mpg, the 750 mile trip would use 5 gallons per passenger, compared to 6.25 for the flight above. This is a savings of \$5, at a cost of 20 hours of a passenger’s life. Even train speeds were doubled, the trip would still take 10 hours including stops, and the energy cost would be higher. As for price, beyond the costs of wages, capital, interest, profit, taxes, and depot fees, trains have to add the cost of new track and track upkeep. Wages too will be higher because the trip takes longer. While I’d be happy to see better train signaling to allow passenger trains to go 100 mph on current, freight-compatible lines, I can’t see the benefit of government-funded super-track for 150+ mph trains that will still take 10 hours and will still be half-full.

Something else removing my enthusiasm for super trains is the appearance of new short take-off and landing jets. Some years ago, I noted that Detroit’s Coleman Young airport no longer has commercial traffic because its runway was too short, 1051m. I’m happy to report that Bombardier’s new CS100s should make small airports like this usable. A CS100 will hold 120 passengers, requires only 1463m of runway, and is quiet enough for city use. The economics are such that it’s hard to imagine mag-lev beating this for the proposed US high-speed train routes: Dallas to Houston; LA to San José to San Francisco; or Chicago-Detroit-Toledo-Cleveland-Pittsburgh. So far US has kept out these planes because Boeing claims unfair competition, but I trust that this is just a delay. For shorter trips, I note that modern busses are as fast and energy efficient as trains, and far cheaper because they share the road costs with cars and trucks.

If the US does want to spend money, I’d suggest improving inner-city airports, and to improve roads for higher speed car and bus traffic. If you want low pollution and high efficiency, how about hydrogen hybrid buses?

Robert Buxbaum, October 30, 2017. I taught engineering for 10 years at Michigan State, and my company, REB Research, makes hydrogen generators and hydrogen purifiers.

Fat people live longer, show less dementia

Life expectancy is hardly affected by weight in the normal – overweight – obese range. BMI 30-34.9 = obese.

Lets imagine you are a 5’10” man and you weigh 140 lbs. In that case, you have a BMI of 20, and you probably think you’re pretty healthy, or perhaps you think you’re a bit overweight. Our institutes of health will say that you are an “average-wight” or “normal-weight” American, and then claim that the average-weight American is overweight. What they don’t tell you, is that low weight, and so-called average weight people in the US live shorter lives. Other things being equal, the morbidity (chance of death) for a thin American, BMI 18.5 is nearly triple that of someone who’s obese, BMI 32. The morbidity of the normal-weight American is better, but is still nearly double that of the obese fellow whose BMI is 32.

Our NIH has created a crisis of overweight Americans, that is not based on health. They work hard to solve this obesity crisis by telling people to jog to work, and by creating ever-more complicated food pyramids. Those who listen live shorter lives. A prime example is Jim Fixx, author of several running books including “The complete Book of Running.” He was 52 when he died of a heart attack while running. Similar to this is the diet-expert, Adelle Davis, author of “Let’s eat right to keep fit”. She died at 70 of cancer — somewhat younger than the average American woman. She attributed her cancer to having eaten junk food as a youth. I would attribute it to being thin. Not only do thin people live shorter lives, but their chances of recovering from cancer, or living with it, seem to improve if you start with some fat.

The same patter exists where age-related dementia is concerned. If you divide the population into quartiles of weight, the heaviest has the least likelihood of dementia, the second heaviest has the second-least, the third has the third-least, and the lightest Americans have the highest likelihood of dementia. Here are two studies to that effect, “Association between late-life body mass index and dementia”, The Kame Project, Neurology. 2009 May 19; 72(20): 1741–1746. And “BMI and risk of dementia in two million people over two decades: a retrospective cohort study” The Lancet, Volume 3, No. 6, p431–436, June 2015.

Morbidity and weight, uncorrected data, and corrected by removing the demented. The likelihood of dementia decreases with weight.

Now you may think that there is a confounding, cause and effect here: that crazy old people don’t live as long. You’d be right there, crazy people don’t live as long. Still, if you correct the BMI-mortality data to remove those with dementia, you still find that in terms of life-span, for men and women, it pays to be overweight or obese but not morbidly so. The study concludes as follows: “Weight loss was related to a higher mortality risk (HR = 1.5; 95% CI: 1.2,1.9) but this association was attenuated when persons with short follow-up or persons with dementia were excluded.” As advice to those who are planning a weight loss program, you might go crazy and reduce your life-span a lot, but if you don’t go crazy, you’re only reducing your life-span a little.

In terms of health food, I’ve noticed that many non-health foods, like alcohol and chocolate are associated with longevity and mental health. And while low-impact exercise helps increase life-span, that exercise is only minimally associated with weight loss. Mostly weight loss involves changing the amount you eat and changing your clothes choices to maximize radiant heat loss.

Dr. Robert E. Buxbaum, October 26, 2017. A joke: Last week I was mugged by a vegan. You may ask how I know it was a vegan. He told be before running off with my wallet.

magnetic separation of air

As some of you will know, oxygen is paramagnetic, attracted slightly by a magnet. Oxygen’s paramagnetism is due to the two unpaired electrons in every O2 molecule. Oxygen has a triple-bond structure as discussed here (much of the chemistry you were taught is wrong). Virtually every other common gas is diamagnetic, repelled by a magnet. These include nitrogen, water, CO2, and argon — all diamagnetic. As a result, you can do a reasonable job of extracting oxygen from air by the use of a magnet. This is awfully cool, and could make for a good science fair project, if anyone is of a mind.

But first some math, or physics, if you like. To a good approximation the magnetization of a material, M = CH/T where M is magnetization, H is magnetic field strength, C is the Curie constant for the material, and T is absolute temperature.

Ignoring for now, the difference between entropy and internal energy, but thinking only in terms of work derived by lowering a magnet towards a volume of gas, we can say that the work extracted, and thus the decrease in energy of the magnetic gas is ∫∫HdM  = MH/2. At constant temperature and pressure, we can say ∆G = -CH2/2T.

With a neodymium magnet, you should be able to get about 50 Tesla, or 40,000 ampere meters At 20°C, the per-mol, magnetic susceptibility of oxygen is 1.34×10−6  This suggests that the Curie constant is 1.34 x293 = 3.93 ×10−4  At 20°C, this energy difference is 1072 J/mole. = RT ln ß where ß is the concentration ratio between the O2 content of the magnetized and un-magnetized gas.

From the above, we find that, at room temperature, 298K ß = 1.6, and thus that the maximum oxygen concentration you’re likely to get is about 1.6 x 21% = 33%. It’s slightly more than this due to nitrogen’s diamagnetism, but this effect is too small the matter. What does matter is that 33% O2 is a good amount for a variety of medical uses.

I show below my simple design for a magnetic O2 concentrator. The dotted line is a permeable membrane of no selectivity – with a little O2 permeability the design will work better. All you need is a blower or pump. A coffee filter could serve as a membrane.

This design is as simple as the standard membrane-based O2 concentrator – those based on semi-permeable membranes, but this design should require less pressure differential — just enough to overcome the magnet. Less pressure means the blower should be smaller, and less noisy, with less energy use.  I figure this could be really convenient for people who need portable oxygen. With several stages and low temperature operation, this design could have commercial use.

On the theoretical end, an interesting thing I find concerns the effect on the entropy of the magnetic oxygen. (Please ignore this paragraph if you have not learned statistical thermodynamics.) While you might imagine that magnetization decreases entropy, other-things being equal because the molecules are somewhat aligned with the field, temperature and pressure being fixed, I’ve come to realize that entropy is likely higher. A sea of semi-aligned molecules will have a slightly higher heat capacity than nonaligned molecules because the vibrational Cp is higher, other things being equal. Thus, unless I’m wrong, the temperature of the gas will be slightly lower in the magnetic area than in the non-magnetic field area. Temperature and pressure are not the same within the separator as out, by the way; the blower is something of a compressor, though a much less-energy intense one than used for most air separators. Because of the blower, both the magnetic and the non magnetic air will be slightly warmer than in the surround (blower Work = ∆T/Cp). This heat will be mostly lost when the gas leaves the system, that is when it flows to lower pressure, both gas streams will be, essentially at room temperature. Again, this is not the case with the classic membrane-based oxygen concentrators — there the nitrogen-rich stream is notably warm.

Robert E. Buxbaum, October 11, 2017. I find thermodynamics wonderful, both as science and as an analog for society.

How Tesla invented, I think, Tesla coils and wireless chargers.

I think I know how Tesla invented his high frequency devices, and thought I’d show you, while also explaining the operation of some devices that develop from in. Even if I’m wrong in historical terms, at least you should come to understand some of his devices, and something of the invention process. Either can be the start of a great science fair project.

The start of Tesla’s invention process, I think, was a visual similarity– I’m guessing he noticed that the physics symbol for a spring was the same as for an electrical, induction coil, as shown at left. A normal person would notice the similarity, and perhaps think about it for a few seconds, get no where, and think of something else. If he or she had a math background — necessary to do most any science — they might look at the relevant equations and notice that they’re different. The equation describing the force of a spring is F = -k x  (I’ll define these letters in the bottom paragraph). The equation describing the voltage in an induction coil is not very similar-looking at first glance, V = L di/dt.  But there is a key similarity that could appeal to some math aficionados: both equations are linear. A linear equation is one where, if you double one side you double the other. Thus, if you double F, you double x, and if you double V, you double dI/dt, and that’s a significant behavior; the equation z= atis not linear, see the difference?

Another linear equation is the key equation for the motion for a mass, Newton’s second law, F = ma = m d2x/dt2. This equation is quite complicated looking, since the latter term is a second-derivative, but it is linear, and a mass is the likely thing for a spring to act upon. Yet another linear equation can be used to relate current to the voltage across a capacitor: V= -1/C ∫idt. At first glance, this equation looks quite different from the others since it involves an integral. But Nicola Tesla did more than a first glance. Perhaps he knew that linear systems tend to show resonance — vibrations at a fixed frequency. Or perhaps that insight came later.

And Tesla saw something else, I imagine, something even less obvious, except in hindsight. If you take the derivative of the two electrical equations, you get dV/dt = L d2i/dt2, and dV/dt = -1/C i . These equations are the same as for the spring and mass, just replace F and x by dV/dt and i. That the derivative of the integral is the thing itself is something I demonstrate here. At this point it becomes clear that a capacitor-coil system will show the same sort of natural resonance effects as shown by a spring and mass system, or by a child’s swing, or by a bouncy bridge. Tesla would have known, like anyone who’s taken college-level physics, that a small input at the right, resonant frequency will excite such systems to great swings. For a mass and spring,

Basic Tesla coil. A switch set off by magnetization of the iron core insures resonant frequency operation.

resonant frequency = (1/2π) √k/m,

Children can make a swing go quite high, just by pumping at the right frequency. Similarly, it should be possible to excite a coil-capacitor system to higher and higher voltages if you can find a way to excite long enough at the right frequency. Tesla would have looked for a way to do this with a coil capacitor system, and after a while of trying and thinking, he seems to have found the circuit shown at right, with a spark gap to impress visitors and keep the voltages from getting to far out of hand. The resonant frequency for this system is 1/(2π√LC), an equation form that is similar to the above. The voltage swings should grow until limited by resistance in the wires, or by the radiation of power into space. The fact that significant power is radiated into space will be used as the basis for wireless phone chargers, but more on that later. For now, you might wish to note that power radiation is proportional to dV/dt.

A more -modern version of the above excited by AC current. In this version, you achieve resonance by adjusting the coil, capacitor and resistance to match the forcing frequency.

The device above provides an early, simple way to excite a coil -capacitor system. It’s designed for use with a battery or other DC power source. There’s an electromagnetic switch to provide resonance with any capacitor and coil pair. An alternative, more modern device is shown at left. It  achieves resonance too without the switch through the use of input AC power, but you have to match the AC frequency to the resonant frequency of the coil and capacitor. If wall current is used, 60 cps, the coil and capacitor must be chosen so that  1/(2π√LC) = 60 cps. Both versions are called Tesla coils and either can be set up to produce very large sparks (sparks make for a great science fair project — you need to put a spark gap across the capacitor, or better yet use the coil as the low-voltage part of a transformer.

Another use of this circuit is as a transmitter of power into space. The coil becomes the transmission antenna, and you have to set up a similar device as a receiver, see picture at right. The black thing at left of the picture is the capacitor. One has to make sure that the coil-capacitor pair is tuned to the same frequency as the transmitter. One also needs to add a rectifier, the rectifier chosen here is designated 1N4007. This, fairly standard-size rectifier allows you to sip DC power to the battery, without fear that the battery will discharge on every cycle. That’s all the science you need to charge an iPhone without having to plug it in. Designing one of these is a good science fair project, especially if you can improve on the charging distance. Why should you have to put your iPhone right on top of the transmitter battery. Why not allow continuous charging anywhere in your home. Tesla was working on long-distance power transmission till the end of his life. What modifications would that require?

Symbols used above: a = acceleration = d2x/dt2, C= capacitance of the capacitor, dV/dt = the rate of change of voltage with time, F = force, i = current, k = stiffness of the spring, L= inductance of the coil, m = mass of the weight, t= time, V= voltage, x = distance of the mass from its rest point.

Robert Buxbaum, October 2, 2017.

Military heroes, Genghis and confederate

This 13 story statue of Genghis Kahn looks over the plains of Mongolia.

All military statues are offensive, as best I can tell. Among the most offensive, is the 131 foot tall monument to Genghis Kahn in central Mongolia. Genghis Kahn is known for near-perfect military success, and for near-total disregard for non-Mongols; he treated them as cattle, to be herded, slaughtered, raped or pillaged. I imagine this statue is offensive to Chinese, Russians, Koreans, Moslems, Jews, Hindus, Poles, and Germans — people he slaughtered by the millions. For some Mongols too, I imagine this statue is offensive as a sad reminder that Mongolia no longer rules the eastern world. But the monument is not for the maudlin, nor is it intended to offend. Like other military statues, the Genghis monument is a rally point for soldiers, old and new. It’s a way to inspire Mongols to be great leaders of men, military and not. Such will see, in Genghis, a man who made tough choices, and carried through to great achievements. That he killed and oppressed others will be justified by noting he did it to keep his Mongols from being killed or oppressed. The grand size is chosen to encourage Mongols to think big.

Genghis appears in fictional form as the villain, Shan Yu, in Mulan. There, his motivation is he doesn’t like the wall. Mulan and the Chinese army stop his Mongol attack by burying them at a snow-covered mountain pass. Historically, a Chinese army did meet Genghis and his army at a mountain pass, but the Mongols were not defeated. Instead they bypassed the Chinese and captured their supplies. Genghis then offered the starving Chinese a choice: join or die. Those that joined had to fight those who did not. A few months later, Peking fell, and in a few years, the rest of Asia. Few of the turncoats survived. Given the same choice, Genghis’s men never turned on him.

General Lee planted a maple tree on this spot in Fort Hamilton, New York. in 2017 the plaque is removed as offensive.

Genghis’s most famous saying is that one arrow is easily broken, but a bundle will overcome any adversary. Similar to this, he is supposed to have said that, if you treat your soldiers as sons, they will follow you even into death. Such words are nonsense to non-soldiers and professional complainers: those who do not imagine themselves going to war. Those who go to war as generals know this is how to behave; those who go as soldiers hope for a leader who values them as sons, and not as cannon fodder.

In the US we’ve begun removing all monuments to the southern forces of the Civil War. This may be a mistake, but it seems irreversible. We’ve kept our monuments for Northern generals including William Sherman, known for his tactic of total destruction, and for Phillip Sheridan, equally known for total war, and for the saying: “The only good Indian is a dead Indian.” But we no longer tolerate Confederates. Among the reasons is that we claim to ease the pain of black people — a pain I feel looking at the Genghis Kahn monument. Another reason, we’re told, is that the statues are “dog-whistles” to racists and white supremacists — a particular danger now, evidenced in the election of Donald Trump. A danger, I think, that’s been largely trumped up as a way to keep politicians and newscasters politically relevant.

For these reasons, or politicians have removed every last confederate monument in Florida, the last being a large grave-stone in the Woodlawn cemetery. Virginia’s governor has similarly declared his intention to remove them all from his state. The city of Baltimore removed all four civil-war monuments in the middle of one busy night, August 18, 2017, and the University of Texas did similarly, working at night. New York City removed a plaque remembering Robert E. Lee for planting a tree at Ft. Hamilton, And, last week, an honorary window at the Washington cathedral where Lee had been a deacon.

Statues of Robert E. Lee are a particular target. There are quite a few in Virginia where his family was prominent — it was Richard H. Lee’s motion in the Continental Congress that carried as independence; his home now serves as Arlington Cemetery. While Lee opposed slavery and freed his slaves before the war, he fought for the Confederacy, so clearly he didn’t oppose slavery as totally as we would like. And Lee only freed his wife’s inherited slaves in 1862, fairly late, though Grant still had slaves at that time. Besides, in 1852, Lee caused an escaped slave to be whipped. I imagine he did the same to runaway soldiers. Historians used to praise Lee, but now call him a cruel racist. In hindsight, we imagine we would have done much better.

General Lee statue being removed from the University of Texas.

As best I can tell, Virginians still remember Lee fondly, particularly soldiers, veterans, and those who imagine themselves leading men in difficult situations. When I try to put myself in Lee’s position, I find I can’t imagine myself doing better or achieving more. His life involved thousands of divisions and hundreds of inspiring actions. In the choice to fight for Virginia and not for the north, I note that Lee was given the same no-win choice as Genghis’s trapped Chinese: join the Union army and kill your brothers, or be killed by that army. The exchange appears in this movie. I admire Lee’s courage to stand by his brothers; it seems the more honorable of two bad choices. Early in his life, Lee committed himself to only honorable behavior  — according to his conception. This is all I expect from myself, and the most I hope for from any other person.

Another thing is Lee’s surrender. I find it a model of how to end a war so that lasting peace is achieved. It’s remembered in Johnny Cash’s song, “God Bless Robert E. Lee.”  Another song, “The night they drove old Dixie down” calls Lee “the very best.” I would be hard pressed to find a better US general: one who won more or was better loved.

Japanese resettlement in WWII. Our history is full of painful decisions by people we admire. Let’s try to not repeat our mistakes or pretend we don’t make them.

A killer complaint lodged against Lee, and against all the confederates, is that they were traitors. If so, George Washington and Ben Franklin were traitors too. In England, Benedict Arnold is honored as a patriot with a statue on Trafalgar square, but we do not honor him, rightly I think. He turned on his friends and brothers. I think it’s politics that’s motivated the current spate of removal. Most of the confederate statues stand (stood) in Democrat-leaning cities of five Republican-leaning states: Virginia, Texas, Georgia, North Carolina, and Mississippi. The white, non-college country-folk of these states are being pitted against the darker, college-educated city folk in a fight for their hearts and pocket books.

As for my guess at interpretation of the statues themselves. I’m inclined to suggest that the statues and their inscriptions do not appear racists to me, so much as soldierly. The statues were largely erected between the Spanish-American war and WWII with soldierly (to my eyes) comments. Baltimore monument to Jackson and Lee, reads on one side: “STRAIGHT AS THE NEEDLE TO THE POLE JACKSON ADVANCED TO THE EXECUTION/ OF MY PURPOSE” and on the other side: “SO GREAT IS MY CONFIDENCE IN GENERAL LEE THAT I AM WILLING TO FOLLOW HIM BLINDFOLDED.” Another Baltimore inscription: “THEY FOUGHT AS GENTLEMEN.” To me this latter is a swipe at Sherman and Sheridan, who did not. Removing these statues is a swipe at the honor of southern soldiers. The statues now read “BLACK LIVES MATTER,” a slogan I read as anti-police, anti-Trump, and anti-white.

The remnant of Baltimore’s Lee – Jackson statue with the old inscription and the new..To me, the old inscription is military, mostly, and not as racist as the new.

The pain of black America is real, but the thing that’s missed is that it is similar to the pain of rural white America. Both have been left behind. I’ve noted that urban black Americans and rural whites have virtually no savings, It could be the two poor cultures don’t realize they have much in common. Or it could be (I think) some folks purposefully fermenting dissension. What is needed, at least is better financial sense, and a recognition that race isn’t racism, but to listen to CNN or read the New York Times, such understandings seem unlikely. The Trump election shocked everyone, I think, those who voted for him and those who didn’t — and perhaps even Trump himself. Hillary, it seems had already bought a house in DC to house her staff. The surprise is not a reason to turn on one’s fellow. I can hope that Trump will prove to be a great president. For now, he is the president, and we are faced by nuclear enemies. It hardly helps to see half of our electorate call the other half racists and deplorables. As with a bundle of arrows, we have strength in union, weakness in disunion. May we all be blessed for a good, sweet year of peace and brotherly love

Robert E. Buxbaum. September 24, 2017. Perhaps my fondness for Lee is because I’m named after him. Here’s my theory for why Mongol arrows flew further.

One of the great patterns of government is that it continually expands adding overseers over overseers to guarantee that those on the bottom do their work honestly. There are overseers who check that folks don’t overcharge, or take bribes, or under-pay. There are overseers to check shirking, and prevent the hiring of friends, to check that paperwork is done, and to come up with the paperwork, and lots of paperwork to assert that no one is wasting money or time in any way at all. There have been repeated calls for regulation reform, but little action. Reform would require agreement from the overseers, and courage from our politicians. Bureaucracy always wins.

By 2009 the number of health administrators was rising dramatically faster than the number of doctors; it’s currently about 20:1.

The call for reform is particularly strong in healthcare and the current, Obamacare rules are again under debate. As of 2009 we’d already reached the stage where there were fourteen healthcare administrators for every doctor (Harvard Business Review), and that was before Obamacare. By 2013, early in the Obamacare era, the healthcare workforce had increased by 75%, but 95 percent of those new hires were administrators: we added 19 administrators per doctor. Some of those administrators were in government oversight, some worked in hospitals filling out forms, some were in doctors offices, and some were in the government, writing the new rules and checking that the rules were followed. A lot of new employment with no new productivity. Even if these fellows were all honest and alert, there are so many of them, that there seems no way they do not absorb more resources than the old group of moderately supervised doctors would by laziness and cheating.

Overseers fill ever-larger buildings, hold ever-more meetings, and create ever-more rules and paperwork. For those paying out of pocket, the average price of healthcare has risen to \$25,826 a year for a family of four. That’s nearly half of the typical family income. As a result people rarely buy healthcare insurance (Obamacare) until after they are too sick to work. Administering the system take so much doctor time that a Meritt Hawkins study finds a sharp decline in service. The hope is that Congress will move to reverse this — somehow.

With more administrators than workers, disagreements among management becomes the new normal. Doctors find themselves operating in “The Dilbert Zone”.

Both Democrats and Republicans have complained about Obamacare and campaigned to change or repeal it, but now that they are elected, most in congress seem content to do nothing and blame each other. If they can not come up with any other change, may I suggest a sharp decrease in the requirements for administrative oversight, with a return to colleague oversight, and a sharp decrease in the amount of computerized documentation. The suggestion of colleague oversight also appears here, Harvard Business Review. Colleague oversight with minimal paperwork works fine for plumbers, and electricians; lawyers and auto-mechanics. It should work fine for doctors too.

Robert Buxbaum, September 19, 2017. On a vaguely similar topic, I ask is ADHD is a real disease, or a disease of definition.

Estimating the strength of an atom bomb

As warfare is a foundation of engineering, I thought I’d use engineering to evaluate the death-dealing power of North Korea’s atomic/hydrogen bomb, tested September 3, 2017. The key data in evaluating a big bomb is its seismic output. They shake the earth like earthquakes do, and we measure the power like earthquakes, using seismometers. I’ve seen two seismographs comparing the recent bomb to the previous. One of these, below, is from CTBTO, the Center for Test Ban Treaty Oversight, via a seismometer in western Kazakhstan (see original data and report).

Seismic output, to scale, of all declared DPNK nuclear tests as observed from IMS station AS-59 in Western Kazakhstan

North Korea’s previous bomb, exploded 9 September 2016, was reported to be slightly more powerful than the ones we dropped on Hiroshima and Nagasaki, suggesting it was about 20 kilotons. According to CTBTO, it registered 5.3 on the Richter scale. The two tests before that appear somewhat less powerful, perhaps 7-10 kilotons, and the two before that appear as dismal failures — fizzles, in atomic bomb parlance. The MOAB bomb, by comparison, was 9 Tons, or 0.009 kiloTons, a virtual non-entity.

To measure the output of the current bomb, I place a ruler on my screen and measure the maximum distance between the top to bottom wiggles. I find that this bomb’s wiggles measure 5 cm, while the previous measures 5 mm. This bomb’s wiggles are ten times bigger, and from this I determine that this explosion registered 6.3 on the Richter scale, 1.0 more than the previous — the Richter scale is the logarithmic measure of the wiggle amplitude, so ten times the shake magnitude  is an addition of 1.0 on the scale. My calculation of 6.3 exactly matches that of the US geological survey. The ratio of wiggle heights was less on the, NORSAR seismometer, Norway, see suggesting 5.8 to 5.9 on the Richter scale. The European agencies have taken to reporting 6.1, an average value, though they originally reported only the 5.8 from NORSAR, and a bomb power commensurate with that.

We calculate the bomb power from the Richter-scale measure, or the ratio of the wiggles. Bomb power is proportional to wiggle height to the 3/2 power. Using the data above, ten times the wiggle, this bomb appears to be 10^3/2 = 31.6 times as powerful as the last, or 31.6 x 20kTon = 630kTon (630,000 tons of TNT). If we used the European value of 6.1, the calculated power would be about half this, 315 kTons, and if we used the NORSAR’s original value, it would suggest the bomb had less than half this power. Each difference of 0.2 on the Richter scale is a factor of two in power. For no obvious reason we keep reporting 120 to 160 kTons.

NORSAR comparison of North Korean blasts — suggests the current bomb is smaller; still looks like hydrogen.

As it happens, death power is proportional to the kiloton power, other things being equal. The bombs we dropped on Hiroshima and Nagasaki were in the 15 to 20 kTon range and killed 90,000 each. Based on my best estimate of the bomb, 315 kTons, I estimate that it would kill 1.6 million people if used on an industrial city, like Seoul, Yokohama, or Los Angeles. In my opinion, this is about as big a bomb as any rational person has reason to make (Stalin made bigger, as did Eisenhower).

We now ask if this is an atom bomb or a hydrogen-fusion bomb. Though I don’t see any war-making difference, if it’s a hydrogen bomb that would make our recent treaty with Iran look bad, as it gave Iran nuclear fusion technology — I opposed the treaty based on that. Sorry to say, from the seismic signature it looks very much like a hydrogen bomb. The only other way to get to this sort of high-power explosion is via a double-acting fission bomb where small atom bomb sets off a second, bigger fission bomb. When looking at movies of Eisenhower-era double-acting explosions, you’ll notice that the second, bigger explosion follows the first by a second or so. I see no evidence of this secondary-delay in the seismic signature of this explosion, suggesting this was a hydrogen bomb, not a double. I expect Iran to follow the same path in 3-4 years.

As a political thought, it seems to me that the obvious way to stop North Korea would be to put pressure on China by making a military pact with Russia. Until that is done, China has little to fear from a North Korean attack to the south. Of course, to do that we’d likely have to cut our support of NATO, something that the Germans fear. This is a balance-of-power solution, the sort that works, short of total annihilation. It was achieved at the congress of Vienna, at the treaty of Ghent, and by Henry Kissinger through détente. It would work again. Without it, I see the Korean conflict turning hot again, soon.

Robert Buxbaum, September 11, 2017.

Japanese zen art – just go away

Japanese zen spiral — it’s a cartoon about meditation. It looks like a monk and a spiral, and note that both ends point inward. Cute.

The purpose of art is not generally to show the world as it is, but to show a new, better way to look at the world. As such, my take on Japanese zen art, is that it is a very cool, fun way to say “just go away.” What follows are some nice (to my eyes) examples, with my commentary.

As with most Japanese art, the zen art looks simpler and more free-form than western religious art. In a sense that is true: there are far fewer lines, but the paintings take as long to make, to a good estimate, since they only appear to have been made with casual ease: flicks of the wrist and waves of the hand. In actuality the artist had a vision of what he wanted, and then made free-hand waving copy after copy until he had some correct, free-looking ones ready for delivery. Because of this, you can look for a meaning in every wiggle — something that you would not do with US free-form abstracts, or with religious paintings of the 1600s. Take daVinci’s last supper — the grand layout is clearly planned and meaningful, the details of the wrinkles, not really. With these, though, no detail is accidental, and the non-accidental sense, as I see it, is “just go away.”

Buddhist Master. Art like this keeps away guests.

Take the spiral at left. It’s sort of cool, and claims to be an allusion to meditation. Mystic, no? As I look carefully a the spiral, the first remarkable thing I see is that it circles in on itself at both ends. At a simple level, I think that’s an allusion to the inward nature of meditation, but note that, at the top end of the coil there’s a wiggle that looks like a face. I take that to be a monk’s face, looking away. The geometry of the coil then suggests the legs and thighs of the rest of the monk (sitting?). If that’s the image (and I think it is) the fact that the monk is facing away from you, leaving you behind suggests to me that the owner has no desire to have you join him. I see nothing in this that would cause another person to want to meditate either. There is nothing attractively persuasive as in western religious art. Here’s an essay I wrote on meditation.

Perhaps it’s just me, but I also imagine these artists living on an industrial treadmill, making painting after painting in his shop and throwing most away because, for example, the monk’s back extended past the paper. Western expressionism also sometimes puts many paintings on a single canvas, but the hidden image stays, at least in a sort-of half shadow. And the wiggles strive to be less learned, even if the faces of some western religious art is distant –even more distant often. At right, above, you’ll find another popular zen-art approach. It shows a zen master in nearly full face. As with most zen art, the master (Buddha or a disciple) looks calm -ish with a sense of the put-upon, as if he were Christ carrying the cross of you being there. Perhaps the intent was to make you go off and meditate, or to see society as worthless, but I think the more-likely message in the master’s look is “why me Lord.” The master looks like he isn’t unhappy with life, just unhappy with you being there. I imagine that this work was placed in a noble’s living room or study for the same reason that many American today put up a picture of Yosemite Sam, sometimes (for those who don’t get art) “Keep Out! This means you.”

A monkey looks at the moon in a well. Don’t touch, the moon seems to say.

As with the Warner-bros. classic, there is a flowing look to the brushwork, but a fair amount of detail. As with the Warner Bros. cartoon, the casual lines seem to serve the purpose of keeping the viewer from taking offense at the message. Sort of like, “Don’t go away mad, just go away.” Cool, but I also like Western cartooning.

As one last example, at left you’ll see a painting illustrating a zen parable. in this case it’s the parable of the monkey’s and the image of the moon. Shown is the moon’s reflection in the water of a well — moon is that big round face. A monkey is about to touch the moon-image, and as we can expect, when the monkey touches the image, it disappears. There are several understandings to be gained from this, e.g. that all is illusion (similar to Plato and his cave), or suggesting that it is better to look at life than to interact with it. Which is the main meaning? In this picture, my sense is that the moon seems put-upon, and afraid. Thus, the lesson I take from the picture is one of inaction: “don’t touch the reflection.” Once again, the choice to depict a frightened moon rather than an impassive one, seems to be the painter’s way of saying “please go away.” Very cool image, but as messages go, that’s the one I see in most Japanese zen art.

Robert Buxbaum, August 17, 2017. I’ve also written on surreal art (I like it a lot, and find it ‘funny’) and on Dada, and conceptual (I like it too, playfully meaningful, IMHO). If you like zen jokes (and who doesn’t) here’s a story of the Buddhist and the hot-dog vendor, and how many zen Buddhists does it take to change a lightbulb? Four. See why.

Kennedy’s perfect, boring college-entry essays

To get into any college you have to write an essay or two, generally including one describing why you want to go that particular college, and many students have trouble. How do I make myself stand out, they ask. My suggestion: Don’t. Make it clear that you want to go, but dare to be dull with the details. John Kennedy did; you can too.

JFK’s dull letter to Harvard. It’s his only essay.

Most school essays limit the number of words. The reviewer too prefers you keep it short. If you want to go to Harvard, or Princeton, or Iowa state, show you can say what needs to be said within the word limit. The first sentence must tell them that you want to go that college, specifically. Mention the college: you want to go to Old Ivy, say. Once that’s taken care of, just state your reasons. Unless you’re going into the writing program, the baldest, simplest terms will work just fine — e.g. that Old Ivy provides an excellent education. It’s better if you can mention a more-specific field of study, e.g. liberal arts or zoölogy, but that’s not necessary. You can now list three or so details to back up your claims. For example, you might mention that the zoölogy program at Old Ivy is well-regarded (mention the school often), that you enjoy their sports team (the ground-hogs, say), or their extracurriculars. Mention that your dad went there or your uncle (and is your hero — hero is a good word) or that you like the location. Surely there is some reason you want to go. If you can mention a famous teacher or alumnus, all the better. Flesh it out if you have space; don’t if you don’t. Conclude with a sentence pointing to the future: that this school will help me do something you want to achieve. You can be specific or not, but don’t lie. Dull is more effective than a lie. I’ve copied, above, John Kennedy’s essay to Harvard, and below his essay to Princeton. These essays follow the pattern, and are dull within the pattern. His conclusion for the first essay: that he wants to go to Harvard to be “a Harvard Man.” He got in. He used the same, dull letter for Princeton, but had more space. For Princeton he said It would have a good effect on me, and that he wanted to be “a Princeton Man.” He got into Princeton too, and went there for two months before switching to Harvard.

John F. Kennedy’s, almost identical letter to Princeton. He got in there too.

You may think that letters like this only work if you are John F. Kennedy, and to some extent that is true. But not totally. I got into Princeton grad school from a background in public school, with no famous relatives or money. My grades were better than JFKs, but my essay had the same structure with some more specifics. As I recall, I explained that I wanted to go to Princeton because I wanted to study chemical engineering in a top department. I may have mentioned a famous professor, and stated I wanted to work on nuclear fusion — a big Princeton specialty at the time. That’s about all, as I recall.

This formula can be tweaked for the other college (and non-college) essays. I’ve previously written about the two speeches at the opening of the Gettysburg cemetery, in 1863. Edwin Everett gave the first speech of the day, excerpted and analyzed here. His speech followed the formula and was lauded. He told folks that it was important that we are here honoring the dead, and followed with three or four reasons for why it was important. His conclusion pointed to the future significance of the events. Republicans and Democrat listeners agreed this was a speech to remember from a scholar of note. Everett’s face graced the \$50 bill for the 40 years after his death.

Abraham Lincoln also spoke at the Gettysburg dedication, but he didn’t follow the formula. He spoke of liberty, and America, and of a government of the people. His speech was panned at the time, even by Republicans. More details here. Though people now see his Gettysburg address as a landmark, at the time even the Republican press didn’t like it  Fortunately for Lincoln and the republic, they warmed to the speech over the next year – in time for the election of 1864. When you apply to college, you want entry now. You can’t wait a year for people to warm to your essay. Stick to the formula. You don’t want the compliment of finding, years from now, that one of the reviewers who rejected you remembers your words fondly. That will be too late. Write for the dull audience in front of you; help them put your application in the “accepted” box. As a last note: If you can not find any truthful reason that you want to go to Harvard or Old Ivy you probably should not be going there. The beginning of wisdom is self-knowledge, and the primary audience for your essay is you.

If you find you have good reasons, but find you need help with the process or with your english grammar, I should mention that my niece owns a company to help folks get into college — link here. She also has a book “From Public School to The Ivy League.

Robert E. Buxbaum, August 7, 2017. Some two years ago, I wrote an essay for my daughter on the joys and pressures of entering her junior year in high school. Here it is.

Activated sludge sewage treatment bioreactors

I ran for water commissioner of Oakland county in 2016, a county with 1.3 million people and eight sewage treatment plants. One of these plants uses the rotating disk contractor, described previously, but the others process sewage by bubbling air through it in a large tank — the so-called, activated sludge process. A description is found here in Wikipedia, but with no math, and thus, far less satisfying than it could be. I thought I might describe this process relevant mathematics, for my understanding and those interested: what happens to your stuff after you flush the toilet or turn on the garbage disposal.

Simplified sewage plant: a bubbling, plug-flow bio-reactor with 90% solids recycle and a settler used to extract floc solids and bio-catalyst material.

In most of the USA, sanitary sewage, the stuff from your toilet, sink, etc. flows separately from storm water to a treatment plant. At the plant, the sewage is first screened (rough filtered) and given a quick settle to remove grit etc. then sent to a bubbling flow, plug-flow bioreactor like the one shown at right. Not all cities use this type of sludge processes, but virtually every plant I’ve seen does, and I’ve come to believe this is the main technology in use today.

The sewage flows by gravity, typically, a choice that provides reliability and saves on operating costs, but necessitates that the sewage plant is located at the lowest point in the town, typically on a river. The liquid effluent of the sewage, after bio-treatment is typically dumped in the river, a flow that is so great more than, during dry season, more than half the flow of several rivers is this liquid effluent of our plants – an interesting factoid. For pollution reasons, it is mandated that the liquid effluent leaves the plant with less than 2 ppm organics; that is, it leaves the plant purer than normal river water. After settling and screening, the incoming flow to the bio-reactor typically contains about 400 ppm of biomaterial (0.04%), half of it soluble, and half as suspended colloidal stuff (turd bits, vegetable matter, toilet paper, etc). Between the activated sludge bio-reactor and the settler following it manage to reduce this concentration to 2 ppm or less. Soluble organics, about 200 ppm, are removed by this cellular oxidation (metabolism), while the colloidal material, the other 200 ppm, is removed by adsorption on the sticky flocular material in the tank (the plug-flow tank is called an oxidation ditch, BTW). The sticky floc is a product of the cells. The rate of oxidation and of absorption processes are proportional to floc concentration, F and to organic concentration, C. Mathematically we can say that

dC/dt = -kFC

where C and F are the concentration of organic material and floc respectively; t is time, and k is a reaction constant. It’s not totally a constant, since it is proportional to oxygen concentration and somewhat temperature dependent, but I’ll consider it constant for now.

As shown in the figure above, the process relies on a high recycle of floc (solids) to increase the concentration of cells, and speed the process. Because of this high recycle, we can consider the floc concentration F to be a constant, independent of position along the reactor length.

The volume of the reactor-ditch, V, is fixed -it’s a concrete ditch — but the flow rate into the ditch, Q, is not fixed. Q is high in the morning when folks take showers, and low at night. It’s also higher — typically about twice as high — during rain storms, the result of leakage and illegal connections. For any flow rate, Q, there is a residence time in the tank, τ where τ = V/Q. We can now solve the above equation assuming an incoming concentration C° = 400 ppm and an outgoing concentration Co of 2 ppm:

ln (C°/Co) = kFτ

Where τ equals the residence time in the tank. Since τ = V/Q,

ln (C°/Co) = kFV/Q.

The required volume of reactor, V, is related to the flow rate, Q, as follows for typical feed and exit concentrations:

V = Q/kF ln( 400/2) = 5.3 Q/kF.

The volume is seen to be dependent on F. In Oakland county, thank volume V is chosen to be one or two times the maximum expected value of Q. To keep the output organic content to less than 2 ppm, F is maintained so that kF≥ 5.3 per day. Thus, in Oakland county, a 2 million gallon per day sewage plant is built with a 2-4 million gallon oxidation ditch. The extra space allows for growth of the populations and for heavy rains, and insures that most of the time, the effluent contains less than 2 ppm organics.

Bob Martin chief engineer the South Lyon, MI, Activated Sludge plant, 2016. His innovation was to control the air bubblers according to measurements of the oxygen content. The O2 sensor is at bottom; the controller is at right. When I was there, some bubblers were acting up.

As you may guess, the activated sludge process requires a lot of operator control, far more than the rotating disk contractor we described. There is a need for constant monitoring and tweaking. The operator deals with some of the variations in Q by adjusting the recycle amount, with other problems by adjusting the air flow, or through the use of retention tanks upstream or downstream of the reactor, or by adding components — sticky polymer, FeCl3, etc. Finally, in have rains, the settler-bottom fraction itself is adjusted (increased). Because of all the complexity. sewer treatment engineer is a high-pay, in demand, skilled trade. If you are interested, contact me or the county. You’ll do yourself and the county a service.

I’d mentioned that the effluent water goes to the rivers in Oakland county. In some counties it goes to the fields, a good idea, I think. As for the solids, in Oakland county, the solid floc is concentrated to a goo containing about 5% solids. (The goo is called unconsolidated sludge) It is shipped free to farmer fields, or sometimes concentrated to more than 5% (consolidated sludge), and provided with additional treatment, anaerobic digestion to improve the quality and extract some energy. If you’d like to start a company to do more with our solids, that would be very welcome. In Detroit the solids are burned, a very wasteful, energy-consuming process, IMHO. In Wisconsin, the consolidated sludge is dried, pelletized, and sold as a popular fertilizer, Milorganite.

Dr. Robert Buxbaum, August 1, 2017. A colleague of mine owned (owns?) a company that consulted on sewage-treatment and manufactured a popular belt-filter. The name of his company: Consolidated Sludge. Here are some sewer jokes and my campaign song.