Few people learn cursive these days with any skill or speed. It’s a shame. This is a form of traditional art and communication. Handwriting is a slower way of writing, that leads to a different type of letter or essay. The sentences are, typically longer, and the words more expressive because the experience of writing and reading cursive is more expressive than with text. The emotional state and energy of the writer comes through the cursive writing, because the writing itself is a form of creative art, adding to the words.
Send a letter or a post card, and you’ve sent a work of art. You’ve communicated words, or course, but far more than with a text or email. First off, there is the picture on the card. You bought that card, or took the picture. Then there is the art of how many words you use. Each letter is directed to only one person, not to 100 as with a text. As a result, people will keep your letter or card far more than they will not keep a text an email. It is more from you, and more to them. You are likely to put more (or different) things in: experiences and feelings that don’t go into an email or text-letter. The size of your writing communicates and even your cross-outs are part of a cursive communication. With email or text, there are no natural cross outs, and you can send the same letter to 100 people, so you write more blandly, with an eye for eventual reuse for someone else. A cursive note is intended for only one person, the one recipient, and this affects both the words, and the form of the words.
Cursive also lends itself to adding a small sketch or doodle. This becomes part of a personal part of the art in a way that does not fit with normal text. It’s calligraphy and conceptional art, an important part of education, and a continuation of western culture. In normal texts, some people have come to add emojis or GIFs, but these are nowhere near as personal or expressive. The cursive letter or note is personal and spicy. It’s an important art form, at least a valid an art form as any that could be taught in school, and it should be.
Robert E. Buxbaum, Sept 1, 2024. I’m running for school board, and like the idea of teaching basic knowledge as a foundation of creativity. One of these basics, I think, is cursive writing.
It’s hard to notice the lack of something, but there’s been a sharp drop-off in the the number of serial killers. Nearly gone are folks like John Wayne Gacy (the clown killer), Jeffrey Dahmer (severed heads, cannibalism, necrophilia), Gary Ridgway, “The Green River Killer” (71 prostitutes killed). Mostly, they were sexual sadists, men who’d have sex with strangers (able or female) and then kill them. In 1987, there were 198 active in the US and many more inactive; by 2018 it was down to 12. And these few are less-prolific, and less-colorful, like Anthony Robinson, “the shopping cart killer”, who killed 4-6 in DC, transporting the bodies in shopping carts.
It’s not clear why there are so few these days. Perhaps it’s the prevalence of surveillance cameras, or improvements in DNA and other pic technology. But these explanations don’t explain why there were so few before 1960. There were some mass murderers, “Jack the Ripper,” “the Boston Strangler” but few before 1960.
Police like to credit the drop off to their detective skills, but there are still plenty of violent crimes that go unsolved, about half the murders in Detroit for example, or most of the rapes in Europe. I suspect that serial killing spiked up in the 60s because of a spike in friendliness, and spiked down in the 2000s because it ended. Before the hippy era, people were cautious of gangsters, rapists, homosexuals, and spies under the bed. But that changed in the 60s. Folks thought it was cool to hitchhike, or pick up random guys. Now, we’re back to being cautious.
A personal story: I was visiting Toronto in the late 1980s and someone I didn’t know overheard that I was planning to drive back to Detroit that afternoon. He asked if I would not mind driving his teenaged daughters to Detroit to see their grandmother, and I said “yes.” At the border, the guards asked who these girls were, and I said I didn’t know. I hadn’t asked. The border guards let us through without passports after a call to the grandmother. I would not be as ready to offer a ride today, and the parents would not be as trusting, nor would the guards.
Serial killings are down since 1990, but mass shootings are up.
Despite much the stricter gun laws, there’s been a rise in crime and a steady growth in the number of murderers in our major cities. There’s also been a rise in synagogue attacks, and a rise in mass murders. These folks kill many in one day or as part of gang-drug activity. Stricter gun laws seem to have made things worse, not better. They do not stop the killers and they hamper the defenders. I took a look at synagogue attacks, and find a pistol would have helped.
On a societal level, I think it would help to have fewer illegal aliens, or aliens who enter with no positive record or skills. It would help to have psychological treatment and lockup for crazy folks and prisoners. Currently, we send violent crazy folks out on the streets until they do something true horrific. More consistent prison sentences are needed for criminals too. We’ now’ve come to use the courts for political theater: Biden’s son should not go to jail for years because he lied on a gun purchase, nor should Trump get for putting down a prostitute as “legal fees”. Nor is his half-billion dollar fine appropriate. Minor crime deserves minor punishment. As a result of our crazy courts, violent criminals are let go as with the MSU killings near me. He was a crazy violent black man, and there was no way, in the law to give him a short sentence, or counseling, or job training. When our incarcerated leave prison, they have anger, plus no jobs or skills. Don’t be surprised when these folks turn to violent crime.
Germany’s green transition is a disaster. Twenty years ago, Germany had 23 nuclear power plants that generated 30% of the country’s electricity cleanly, cheaply, and reliably. These plants have all been shut by the government as part of a commitment to clean energy. What could be cleaner? Germany has switched to a mix of wind and solar, plus a significant shift to coal power. Wind and solar use a lot of land compared to nuclear, and they break down leaving fields of debris. There is now a lack of electricity to power homes and industries, and what power there is, is unreliable, due to the many dark windless days in Germany.
The lack of reliable electricity is crippling German industry now that Russian gas has been cut off. In this environment, why would the Germans order special trains and boats that burn, hydrogen that’s made from electricity and natural gas? My understanding of the reason is that, Germany sometimes has too much wind power and nothing to do with it. They plan to store this excess by making hydrogen that they can use to power their trains and boats. The cost is high, and the efficiency is poor, but the electricity is free.
Hydrogen is not as compact a fuel as gasoline, nor is it as cheap as electricity, but it’s cleaner than gas, and in some ways it’s better than battery-stored electricity. While hydrogen takes a lot of storage space relative to gasoline, high pressure helps, and the storage is cheaper than with batteries. Also, hydrogen fuel is transferred faster than electric fuels. Trains and ships are chosen for hydrogen because they are good at carrying bulky items. The transition to hydrogen is relatively straightforward with trains, since many are already powered by electricity. Hydrogen fuel cells can make the electricity on board (in theory), while avoiding the need for expensive overhead wires. The idea sort-of makes sense.
Germany’s first hydrogen train. cancelled after 1 year of poor operating.
The first German train to use hydrogen powered them with fuel cells that generated electricity. It began service in October 2022, but the fuel cells proved unreliable. Service ended one year later, October 2023, replaced by polluting diesel (see here). The Hannover line plans to replace these with battery-powered trains over the next few years. There are also plans for a hydrogen-powered ferry, but it is not clear why the ferry should prove more reliable than the train, or cheaper.
San Francisco’s hydrogen-powered ferry, $30 million, 15 knots top speed, 75 passengers, no cars. Long delayed.
In the US, the Biden administration has paid, so far, $30 million for a hydrogen ferry in San Francisco. It’s two years behind schedule and over cost, taking only 75 passengers and no cars at 15 knots, 17mph. In the US, and likely in Germany, most of the hydrogen will be made from natural gas. A better solution, I think would be to power the ferris and trains by natural gas and to store the excess electricity in land-based batteries or as land-based hydrogen for land-based fuel cells.
Germany is committed to electric trains, though, and hydrogen provides a route to power these trains with excess electricity. German customers take the train, in part, because they like them, and in part because German politicians have banned short-hop planes on competing routes, and subsidized electric trains. Yet another option to balance times of excess solar and wind power would be to subsidize electric cars, or at least allow theirs owners to trade electricity: to buy electricity when it’s cheap and resell it to the grid when demand and prices are high.
Heat exchange is a key part of most chemical process designs. Heat exchangers save money because they’re generally cheaper than heaters and the continuing cost of fuel or electricity to run the heaters. They also usually provide free, fast cooling for the product; often the product is made hot, and needs to be cooled. Hot products are usually undesirable. Free, fast cooling is good.
So how do you design a heat exchanger? A common design is to weld the right amount of tubes inside a shell, so it looks like the drawing below. The the hot fluid might be made to go through the tubes, and the cold in the shell, as shown, or the hot can flow through the shell. In either case, the flows are usually in the opposite direction so there is a hot end and a cold end as shown. In this essay, I’d like to discuss how I design our counter current heat exchangers beginning a common case (for us) where the two flows have the same thermal inertia, e.g. the same mass flow rates and the same heat capacities. That’s the situation with our hydrogen purifiers: impure hydrogen goes in cold, and is heated to 400°C for purification. Virtually all of this hot hydrogen exits the purifier in the “pure out” stream and needs to be cooled to room temperature or nearly.
Typical shell and tube heat exchanger design, Black Hills inc.
For our typical designs the hot flows in one direction, and an equal cold flow is opposite, I will show the temperature difference is constant all along the heat exchanger. As a first pass rule of thumb, I design so that this constant temperature difference is 30°C. That is ∆THX =~ 30°C at every point along the heat exchanger. More specifically, in our Mr Hydrogen® purifiers, the impure, feed hydrogen enters at 20°C typically, and is heated by the heat exchanger to 370°C. That is 30°C cooler than the final process temperature. The hydrogen must be heated this last 30°C with electricity. After purification, the hot, pure hydrogen, at 400°C, enters the heat exchanger leaving at 30°C above the input temperature, that is at 50°C. It’s hot, but not scalding. The last 30°C of cooling is done with air blown by a fan.
The power demand of the external heat source, the electric heater, is calculated as: Wheater = flow (mols/second)*heat capacity (J/°C – mol)* (∆Theater= ∆THX = 30°C).
The smaller the value of ∆THX, the less electric draw you need for steady state operation, but the more you have to pay for the heat exchanger. For small flows, I often use a higher value of ∆THX = 30°C, and for large flows smaller, but 30°C is a good place to start.
Now to size the heat exchanger. Because the flow rate of hot fluid (purified hydrogen) is virtually the same as for cold fluid (impure hydrogen), the heat capacity per mol of product coming out is the same as for mol of feed going in. Since enthalpy change equals heat capacity time temperature change, ∆H= Cp∆T, with effectiveCp the same for both fluids, and any rise in H in the cool fluid coming at the hot fluid, we can draw a temperature vs enthalpy diagram that will look like this:
The heat exchanger heats the feed from 20°C to 370°C. ∆T = 350°C. It also cools the product 350°C, that is from 400 to 50°C. In each case the enthalpy exchanged per mol of feed (or product is ∆H= Cp*∆T = 7*350 =2450 calories.
Since most heaters work in Watts, not calories, at some point it’s worthwhile to switch to Watts. 1 Cal = 4.174 J, 1 Cal/sec = 4.174 W. I tend to do calculations in mixed units (English and SI) because the heat capacity per mole of most things are simple numbers in English units. Cp (water) for example = 1 cal/g = 18 cal/mol. Cp (hydrogen) = 7 cal/mol. In SI units, the heat rate, WHX, is:
The flow rate in mols per second is the flow rate in slpm divided by 22.4 x 60. Since the driving force for transfer is 30°C, the area of the heat exchanger is WHX times the resistance divided by ∆THX:
A = WHX * R / 30°C.
Here, R is the average resistance to heat transfer, m2*∆T/Watt. It equals the sum of all the resistances, essentially the sum of the resistance of the steel of the heat exchanger plus that of the two gas phases:
R= δm/km + h1+ h2
Here, δm is the thickness of the metal, km is the thermal conductivity of the metal, and h1 and h2 are the gas-phase heat transfer parameters in the feed and product flow respectively. You can often estimate these as δ1/k1 and δ2/k2 respectively, with k1 and k2 as the thermal conductivity of the feed and product, both hydrogen in my case. As for, δ, the effective gas-layer thickness, I generally estimate this as 1/3 the thickness of the flow channel, for example:
h1 = δ1/k1 = 1/3 D1/k1.
Because δ is smaller the smaller the diameter of the tubes, h is smaller too. Also small tubes tend to be cheaper than big ones, and more compact. I thus prefer to use small diameter tubes and small diameter gaps. in my heat exchangers, the tubes are often 1/4″ or bigger, but the gap sizes are targeted to 1/8″ or less. If the gap size gets too low, you get excessive pressure drops and non-uniform flow, so you have to check that the pressure drop isn’t too large. I tend to stick to normal tube sizes, and tweak the design a few times within those parameters, considering customer needs. Only after the numbers look good to my aesthetics, do I make the product. Aesthetics plays a role here: you have to have a sense of what a well-designed exchanger should look like.
The above calculations are fine for the simple case where ∆THX is constant. But what happens if it is not. Let’s say the feed is impure, so some hot product has to be vented, leaving les hot fluid in the heat exchanger than feed. I show this in the plot at right for the case of 14% impurities. Sine there is no phase change, the lines are still straight, but they are no longer parallel. Because more thermal mass enters than leaves, the hot gas is cooled completely, that is to 50°C, 30°C above room temperature, but the cool gas is heated at only 7/8 the rate that the hot gas is cooled. The hot gas gives off 2450 cal as before, but this is now only enough to heat the cold fluid by 2450/8 = 306.5°. The cool gas thus leave the heat exchanger at 20°C+ 306.8° = 326.5°C.
The simple way to size the heat exchanger now is to use an average value for ∆THX. In the diagram, ∆THX is seen to vary between 30°C at the entrance and and 97.5°C at the exit. As a conservative average, I’ll assume that ∆THX = 40°C, though 50 to 60°C might be more accurate. This results in a small heat exchanger design that’s 3/4 the size of before, and is still overdesigned by 25%. There is no great down-side to this overdesign. With over-design, the hot fluid leaves at a lower ∆THX, that is, at a temperature below 50°C. The cold fluid will be heated to a bit more than to the 326.5°C predicted, perhaps to 330°C. We save more energy, and waste a bit on materials cost. There is a “correct approach”, of course, and it involves the use of calculous. A = ∫dA = ∫R/∆THX dWHX using an analytic function for ∆THX as a function of WHX. Calculating this way takes lots of time for little benefit. My time is worth more than a few ounces of metal.
The only times that I do the correct analysis is with flame boilers, with major mismatches between the hot and cold flows, or when the government requires calculations. Otherwise, I make an H Vs T diagram and account for the fact that ∆T varies with H is by averaging. I doubt most people do any more than that. It’s not like ∆THX = 30°C is etched in stone somewhere, either, it’s a rule of thumb, nothing more. It’s there to make your life easier, not to be worshiped.
I started my own business, rebresearch. It puts food on my table, and provides satisfaction that I’m helping people. It seems to me that other folks, particularly veterans, could benefit from owning their own businesses. Veterans seem to possess more of the skills for successful business startup than found the general population, and I notice that veterans start businesses more than most folk do, too.
Some 50% of returning veterans from WWII started their own businesses, I’ve read, and some were very successful. Walmart, the world’s largest retail company, for example, was founded by WWII Army intelligence officer Sam Walton. Then there’s FedEx, founded by Fred Smith, a Marine Corps Veteran of Vietnam, two tours, where he earned two Purple Hearts, a Bronze Star, and Silver Star.
Both of the above are in supply/ logistics, but veterans also open real estate shops, coffee shops, construction… Their success rate is higher than non-veterans perhaps due to skills they may not appreciate: physical stamina, organization, discipline, and the ability to “get the job done.” Having a successful business requires that you either show up every day at 6:30, or 7:30 — and to have a trusted replacement ready if you can’t. Many folks in the population don’t seem to understand the need to show up. This Is not to say that starting a successful business is easy, even if you show up and know what you’re doing, but reliability and hard work go a long way. Besides, many veterans have specific skills that transfer directly. See below, some business ideas with links to veteran-started companies in each area.
veteran-owned business directory copied from https://www.veteranownedbusiness.com.
One advantage of stating a business over working for others is that you are guaranteed to get hired. And you can hire your wife, etc. Also, there’s a bigger up-side than working for others. There are tax benefits too — your car and computer can be bought with pre-tax dollars assuming you use them in the business. These are not insignificant benefits — usually your tax bracket is higher than your profit margin. You generally have to work more hours per day as an entrepreneur, but if you like the work and have the skills that might not be too bad.
Perhaps you learned cybersecurity
Veterans often have credentials and skills that are rare in the country at large, and this can set you up for a good job. A high security clearance, for example– it’s necessary for many jobs in security –or skills in airplane repair, fire-arms, martial arts, shipping, recruiting, food service, communications, security, commissary… If these areas appeal to you, you can get extra training, either while still in the military or outside, and the gov’t will often pay for it. If you’re already out, think of using your VA benefits to go to school. You’ll want to fill in gaps, too, like in accounting. Good luck.
About 7% of new US car and truck sales in 2023 were electric, 1.2 million vehicles. Of these, about 55% were Teslas. These numbers make sense based on US manufacturing and driving habits, so I don’t expect fast sales growth in 2024.
Currently home owners are the only major group of private drivers that save on fuel cost from owning an EVs. Home owners pay relatively little for electricity, about 11¢ per kWh, and they can generally charge their EVs conveniently, at home, overnight. Charging is more expensive and inconvenient for apartment dwellers. As a result, in 2023, some 95% of US EV sales went to home owners. Over 2 to 3 years they could hope to recover in gasoline savings the $7000 more that their EVs cost compared to petrol-powered vehicles, but they still have to drive a fair amount. A full charge of 80kWh EV at home will cost about $8.80 at current rates. This will power about 250 miles at a cost of 3.5¢/mile = $8.80/250.
Home, level 2 Chargers will cost about $1500 including the electrician cost.
The cost of gasoline is about 16.5¢/mile = $3.80/gal/ 23mi/gal) suggesting that you save 13¢ per mile by owning an EV. In order to recover the extra $7000 cost of the car in two years, you’d have to drive 27,000 miles per year, or 74 miles per day. To recover the difference in three years, you must drive 50 miles per day or 18,000 miles per year. This is more than most people drive.
EVs also offer reduced maintenance, but customers can balance this against the inconvenience of long charge times and spotty availability of chargers. My sense is that the fraction of Americans who benefit and drive 50-75 miles per day is about 7%. This fraction will increase as EVs get cheaper, but families that can benefit already own an EV.
The average Tesla costs today about $3000 more than the equivalent petrol car, but that still makes it relatively expensive, and it seems that the price differential was intentionally set to match sales to Tesla’s production capacity. Tesla could make EVs cheaper than petrol cars and still make a profit on each, but if they did this, they would have too much demand. Other US auto makers are mostly lose money on EVs and are unmotivated to lower prices. Based on this, my sense is that it is unlikely that sales will be much higher in 2024 than the 1.2 million sold in 2023.
The Chinese have plenty of new EVs, and they are eager to export. Their car market is currently about 50% EV, with companies like BYD selling EVs for as little as $12,000. The Chinese government subsidizes production and powers their EVs with cheap electricity by burning coal.These cars do not seem very good, compared to Tesla, but at this price they would flood the market if allowed to compete. The US government has kept them out with tariffs and with complaints about slave labor. Trump has promised a yet higher tariff, 100% on Chinese cars, if elected. The intent is to preserve US jobs and manufacturing. This is one of those situations where tariffs are good, IMHO.
Toyota Prius, the most popular hybrid.
Hybrids are a third option, cheaper than EVs, high mpg than normal engines. Though they are sometimes touted as a transition to EVs, to me they’ seem to suit a completely different demographic: those who don’t own their own home and drive a lot. Toyota makes the most popular hybrids in the US. They cost about $4000 more than the equivalent petrol car, $30,000 for a Prius vs $26,000 for a Corolla. When using a Prius in the city, you’ll get about 50 mpg, spending 7.5¢ per mile ($3.80/gal / 50 mpg = 7.5¢). This implies a gas savings of about 9¢ per mile vs an ordinary Corolla. Based on this, you have to drive about 27,000 miles per year in the city to recover the cost difference in two years. That’s a lot, and your performance is typically worse with a hybrid: you have a heavier car with a small engine. Maintenance cost is also higher with a hybrid than with an EV: you still need oil changes, fluid changes, belts, etc. and the mpg advantage vanishes on the highway. A hard driving home owner is better off with an EV, IMHO, an apartment dweller with a hybrid. Hybrids also should make sense for taxis and local-haul trucks. I can imagine hybrid sales rising in 2024, perhaps as high as 15% of vehicle sales. What we’re all waiting for is more near-shore manufacturing (or mandates), and this is not likely in 2024.
When the UK left the EU, they gained some economic freedom, but lost easy access to their largest trade partner. They avoided having to follow the weird green policies of the EU, and no longer had to take low cost workers from Poland, Bulgaria, Tec, but having lost easy access to European trade, the assumption was that they would want a trade deal soon, with someone, and the likely someone was the USA.
At first things went pretty well. there was the predicted crash didn’t come, showing that the top economists were talking out their hats, or trying to scare people to stay in the EU. And then Trump proposed the first of four attempts at a trade deal, and things got ugly. All four attempts were rejected in a most-forceful and insulting way.
When Trumps first forays at a trade deal were rejected, he attempt a visit in the summer of 2017. The British Parliament forbidding the visit, accepting it only by a slim majority with the PM, May making no strong case. The mayor of London protested with a blimp of Trump as a big baby, and the Queen was not sure she had time for tea (she had time for Obama). Trump cancelled the visit, and May made deals with Norway, Switzerland, Israel, Palestine, and Iceland. Why these but not the US?
Over the next two years Trump made trade deals with Mexico, Canada, Japan, and Korea, trying The UK again in July, 2019. This time, Theresa May was more welcoming — she was facing an election — but the blimp was brought out again, and allowed to follow Trump around England, along with a statue of Trump on the toilet, tweeting, and making fart sounds while saying “witch hunt,” “no collusion*”, and other comic comments. All rather insulting, and deal with the UK was signed.
I suspect Trump’s offers to the UK were similar to those with Japan, and Japan seemed very happy with the deal (Biden offered them an exit from Trump’s, and Abe stayed — and proposed Trump for the Nobel Prize. So why the British antagonism? Even if they had to say no, why didn’t they arrange a location or treatment to say no politely. India said no to Trump’s trade deal, politely, in 2020, and to the UK too.
My theory is that Theresa May was taken by the anti-Trump propaganda of Europe and particularly of the German press (see magazine covers of the time). Germany was the leader of Europe (this status has diminished), and its press presented Trump as a racist murderer. May kept trying to get back into the EU, and may have thought that ill-treating Trump would help. Boris Johnson followed May, and was pro-Trump, but his cabinet was not. They acted as if they could recreate the British empire of Queen Victoria — a silly thought. They tried for free trade deals with India, Turkey, and Saudi Arabia, members of the old empire, but they never quite managed anything. COVID made things worse. The UK economy stalled, Johnson was removed, and the current PM, Rishi Sunak, seems to have got nowhere with Biden. Trump re-offered his trade deal during the visit, but he was out of office; Both Biden and Sunak ignored it.
The UK needs free trade with some substantial countries. They are a hub for manufacturing, information, and banking, currently without any spokes. India likely turned them down because the UK no longer has the power to protect them from enemies, China, Iran, Russia.., nor to protect their trade. Aside from rejoining the EU (good luck there), US is the obvious partner. If personality were the problem, there would have been a deal between Rishi Sunak and Joe Biden.
Since leaving the EU, the UK is doing slightly better than Germany, but that’s not saying much. British exports were helped by the cut off of trade with Russia, but that might not last, and London is having trouble trying to remain a financial center, fighting difficult travel and work rules, and the decline of the pound. Maybe it’s Biden’s fault that there is no deal. It’s hard to tell. Last week, the British Foreign secretary, David Cameron, came to visit Trump at Mar a Lago for a good feelings chat and to start on a trade deal should Trump become president. It’s not clear that Trump will become president, but there are at least hopes for a deal, ideally signed at a distance from the baby balloon.
Robert Buxbaum, April 18, 2024 *”Russian collusion” was a big deal at the time. A dossier was supposed show that Trump was a Russian agent. It turned out the dossier was created by Democrats working with the FBI.
In 1905 and 1908, Einstein developed two formulations for the diffusion of a small particle in a liquid. As a side-benefit of the first derivation, he demonstrated the visible existence of molecules, a remarkable piece of work. In the second formulation, he derived the same result using non-equilibrium thermodynamics, something he seems to have developed on the spot. I’ll give a brief version of the second derivation, and will then I’ll show off my own extension. It’s one of my proudest intellectual achievements.
But first a little background to the problem. In 1827, a plant biologist, Robert Brown examined pollen under a microscope and noticed that it moved in a jerky manner. He gave this “Brownian motion” the obvious explanation: that the pollen was alive and swimming. Later, it was observed that the pollen moved faster in acetone. The obvious explanation: pollen doesn’t like acetone, and thus swims faster. But the pollen never stopped, and it was noticed that cigar smoke also swam. Was cigar smoke alive too?
Einstein’s first version of an answer, 1905, was to consider that the liquid was composed of atoms whose energy was a Boltzmann distribution with an average of E= kT in every direction where k is the Boltzmann constant, and k = R/N. That is Boltsman’s constant equals the gas constant, R, divided by Avogadro’s number, N. He was able to show that the many interactions with the molecules should cause the pollen to take a random, jerky walk as seen, and that the velocity should be faster the less viscous the solvent, or the smaller the length-scale of observation. Einstein applied the Stokes drag equation to the solute, the drag force per particle was f = -6πrvη where r is the radius of the solute particle, v is the velocity, and η is the solution viscosity. Using some math, he was able to show that the diffusivity of the solute should be D = kT/6πrη. This is called the Stokes-Einstein equation.
In 1908 a French physicist, Jean Baptiste Perrin confirmed Einstein’s predictions, winning the Nobel prize for his work. I will now show the 1908 Einstein derivation and will hope to get to my extension by the end of this post.
Consider the molar Gibbs free energy of a solvent, water say. The molar concentration of water is x and that of a very dilute solute is y. y<<1. For this nearly pure water, you can show that µ = µ° +RT ln x= µ° +RT ln (1-y) = µ° -RTy.
Now, take a derivative with respect to some linear direction, z. Normally this is considered illegal, since thermodynamic is normally understood to apply to equilibrium systems only. Still Einstein took the derivative, and claimed it was legitimate at nearly equilibrium, pseudo-equilibrium. You can calculate the force on the solvent, the force on the water generated by a concentration gradient, Fw = dµ/dz = -RT dy/dz.
Now the force on each atom of water equals -RT/N dy/dz = -kT dy/dz.
Now, let’s call f the force on each atom of solute. For dilute solutions, this force is far higher than the above, f = -kT/y dy/dz. That is, for a given concentration gradient, dy/dz, the force on each solute atom is higher than on each solvent atom in inverse proportion to the molar concentration.
For small spheres, and low velocities, the flow is laminar and the drag force, f = 6πrvη.
Now calculate the speed of each solute atom. It is proportional to the force on the atom by the same relationship as appeared above: f = 6πrvη or v = f/6πrη. Inserting our equation for f= -kT/y dy/dz, we find that the velocity of the average solute molecule,
v = -kT/6πrηy dy/dz.
Let’s say that the molar concentration of solvent is C, so that, for water, C will equal about 1/18 mols/cc. The atomic concentration of dilute solvent will then equal Cy. We find that the molar flux of material, the diffusive flux equals Cyv, or that
where Cy is the molar concentration of solvent per volume.
Classical engineering comes to a similar equation with a property called diffusivity. Sp that
Molar flux of y (mols y/cm2/s) = -D dCy/dz, and D is an experimentally determined constant. We thus now have a prediction for D:
D = kT/6πrη.
This again is the Stokes Einstein Equation, the same as above but derived with far less math. I was fascinated, but felt sure there was something wrong here. Macroscopic viscosity was not the same as microscopic. I just could not think of a great case where there was much difference until I realized that, in polymer solutions there was a big difference.
Polymer solutions, I reasoned had large viscosities, but a diffusing solute probably didn’t feel the liquid as anywhere near as viscous. The viscometer measured at a larger distance, more similar to that of the polymer coil entanglement length, while a small solute might dart between the polymer chains like a rabbit among trees. I applied an equation for heat transfer in a dispersion that JK Maxwell had derived,
where κeff is the modified effective thermal conductivity (or diffusivity in my case), κl and κp are the thermal conductivity of the liquid and the particles respectively, and φ is the volume fraction of particles.
To convert this to diffusion, I replaced κl by Dl, and κp by Dp where
Dl = kT/6πrηl
and Dp = kT/6πrη.
In the above ηl is the viscosity of the pure, liquid solvent.
The chair of the department, Don Anderson didn’t believe my equation, but agreed to help test it. A student named Kit Yam ran experiments on a variety of polymer solutions, and it turned out that the equation worked really well down to high polymer concentrations, and high viscosity.
As a simple, first approximation to the above, you can take Dp = 0, since it’s much smaller than Dl and you can take Dl to equal Dl = kT/6πrηl as above. The new, first order approximation is:
D = kT/6πrηl (1 – 3φ/2).
We published in Science. That is I published along with the two colleagues who tested the idea and proved the theory right, or at least useful. The reference is Yam, K., Anderson, D., Buxbaum, R. E., Science 240 (1988) p. 330 ff. “Diffusion of Small Solutes in Polymer-Containing Solutions”. This result is one of my proudest achievements.
There have been many attacks on Jewish schools, homes , and markets. The press likes to blame white supremicists. But in the US, Islamicists and “Black Hebrews” have been the more regular assailants. Along with them are equal opportunity killers — those who kill, for no obvious reason. I note that mostly attackers don’t wear body armor, suggesting that a small revolver is the best choice for defense. The police come, but never in time.
The Monsey, NY, 2019 attack is fairly typical of a small-scale hate crime, though it was not charged as such. A member of the “Black Hebrew” movement who had attacked Jews in the. past, always released by police, waled into a Channuka celebration in a home in Monsey, NY, pulled a large knife, and stabbed the rabbi and four others before being chased out by folks with chairs. One of those stabbed died from the wounds, and several others spent time in hospital. The attacker, undeterred, drove attack another Jewish establishment, a nearby orthodox shul, and attacked there. It seems he’d committed an anti-Jewish stabbing shortly before this murder, but was released as always before the final, deadly attack. As with most black on Jewish attacks, this was not ruled a hate crime by the police.
Kessler before the attack. The claim is that his flag triggered an accidental attack by Professor Alnaji and his compatriot.
In the US Islamic on Jewish attacks tend to be ruled as accidents or legitimate expressions, and never as hate crimes. In Thousand Oaks California, 2023, Paul Kessler 69 was standing with an Israeli flag (right) when two Islamic activists crossed the street to shout at him. One of them, Professor Loay Abdelfattah Alnaji, hit him fatally on the head with a bull horn. The police ruled it accidental, involuntary manslaughter, despite that it was two on one, deliberate, premeditated, and the assailant kept yelling: “stop killing our children,” even after Kessler was down after being hit. Alnaji is free on bail of $50K. It was not ruled a hate crime.
Poway synagog shooter, Shot four, killed one before gun jammed.
The court reacts quite differently to white on Jewish crimes, ruling these hate crimes and punishing to the full extent of the law. An example, in Poway, CA, 2019, a white man, left, entered the Orthodox, Chabad synagog during services carrying a semi-automatic pistol. He shot and killed the first person he met, then shot the rabbi, entered a side room, and shot two more, an adult and an 8 year old. Then his gun jammed. At that point he left, and called 911. He claimed he hated Jews, Moslems, and President Trump. I note that gun jams are common in stressful situations, but police showing up in time is uncommon. A revolver for personal defense would’ve helped, but they are mostly illegal in California — not that the antigun laws deterred the killer.
Organized attacks are more deadly, and almost impossible to defend against. They tend to be Islamic. The recent attack on a music festival in Israel, for example. An air – land assault with machine guns by an armed group civilians (and UN workers!) that left 1500 dead, and 250 captured. Most of the victims were unarmed, but some were armed. They were over-run, and killed. It is very hard to defend against multiple assailants with training and the advantage of surprise.
A smaller-scale versions of these military stile Islamic attacks have play out regularly around the world. For example, Mumbai, 2019, two Islamic activists entered an orthodox Jewish hostel and school, and barricaded themselves in. Over the course of three days, they killed the rabbi and his wife, and five of their children. It was part of a wider program of well-planned attacks on Jews and Jewish businesses in India. The two perpetrators were eventually killed by the police, but the support network escaped justice. These are the folks who planned the attack, and armed the two; IMHO they are as guilty as the murderers.
The shooter who attacked the Hyper Kasher kosher store in Paris. He was trained, but worked alone, and wears no bulletproof vest. First he shot the person nearest to him and those behind the counter — anyone who might reasonably stop him. He then closed the metal grate around the store, started talking and killing for 4 hours. A well timed shot or two could have taken him out.
In Paris, as a similar Islamic general attack on Jews and businesses included the killing of 12 at the humor magazine “Charlie Hebdot” A trained Islamic activist entered a kosher market, “hypercasher” with two Kalashnikov AK47s provided by the same network who armed the Charlie Hebdot killers. Ownership of most guns is illegal in France, but that makes for easy targets. On entering, he immediately killed the person next to him and shot the two people behind the counter (one died). He then asked that the store be sealed by its steel gratings so he could keep on killing in peace. Secure in the market, the attacker then asked if he should kill someone else. When every shouted no, he laughed and killed the person. The killer talked and killed for the next 4 hours while the police gathered outside and watched. One unarmed customer tried to attack him, but was killed in the process, and jeered at besides — jeers seem to be common. Eventually, the French police killed the attacker and rescued those still alive. As with the Indian attack, the support network escaped or were found non-guilty. If someone had a pistol, maybe the killing would have ended quicker.
White supmemicist, right killed 11 in Pittsburgh. Survivor, center picture will testify. From the NY Post.
In Pittsburgh, PA, 2018, a “White supremicist” entered the “tree of life synagogue” with four semi-automatic pistols (three of them Glocks). He killed 11, going from room to room, sometimes talking to people. One survivor hid under the sink for hours, unable to reach his phone in deadly fear that it would ring and expose him. Eventually the killer just left, and as he did, someone with a gun shot after him, missing. Clearly, this fellow had that gun all along but was afraid to draw it, or could not find it. I’m glad he missed, by the way. If he’d hit the guy as he left, the shooter would have gone to jail. According to US law, you can’t shoot a fleeing attacker. My lesson is that you want a gun that’s small enough to hide well and draw easily, and you want to practice enough to be comfortable using it.
Another deadly attack from “Black Hebrews”, this time organized, military stile. In Jersey City, 2019, two “Black Hebrews” attacked the patrons of an orthodox, Kosher market, starting to shoot from the street, from 50 feet away. Once they were sure that no one inside was armed, they entered and killed three individuals who were doing their best to hide. The recent Gaza attacks used this military style, too. They attacked from a distance first to drive folks into hiding, then set the buildings afire or shot cowering individuals point blank. it’s very hard to defend against this sort of attack, especially if you are unarmed, but even if you are armed and trained.
Enhanced photo from the shooting at the Jersey City Kosher market. This is a rare example of military tactics being used. Two attackers of the “Black Hebrews” started shooting from outside the store, and only entered later to finish up.
The majority of other deadly attacks are by “Islamic youths” against older Jews. The youths will enter a house, threaten, kill, and leave. In one case the victim (a professor) was beheaded on the main street. He’d shown cartoons to his class that suggested that Islam is not peaceful. As with beatings that go with “Palestine Independence” rallies, these attacks are not considered “hate crimes,” but teen violence or political expression.
Hate crimes or not, they mostly target Jews, and they seem to be religiously motivated. Typically, it’s only one or two assailants attacking a chosen, visibly orthodox individual or place. Killing is mostly in close quarters over a relatively long period, often jeering the dead. So far, none appear to use a bulletproof vest. The police do not come on time, ever.
From the above, I suggest a stubby revolver for its concealment and reliability. Carrying a gun is not a good idea if you have children in the house, or if you spend a lot of time in schools, even though these are among the locations that need defending most. You need permission to carry in large venues, including big stores, synagogues and churches, as well as most clubs.
J. Edgar Hoover’s 1939, 32 caliber, “Pocket perfect,” Detective.
A gun suggestion is a “detective special” revolver like the S+W 642 “airweight, 14.6 ounces. It’s about half of the weight of a standard Glock, and shoots five bullets of 38 caliber. A step smaller are 32 caliber revolvers as were carried by J. Edgar Hoover. Smaller yet, are 22LR and/or 22WMR, revolvers like the S+W 351C or 351 PD, and all the NAA mini revolvers, 6 to 11 oz. They are easy to carry, non-obvious, and more reliable than a semi. Five to seven bullets can be enough. Robert Kennedy was killed with a 22lr. Semi-automatic pistols are good for the range, but they need to be racked, and tend to jam in tense situations.
I suggest a revolver that takes different loads. You can practice with cheaper ammo, and carry it loaded with more expensive. Especially with semis, make sure you can draw fast and shoot accurately without jamming.
Robert Buxbaum, March 10, 2024. A common claim in the press is that guns should be banned as in Europe, or highly regulated as in New York, New Jersey and California. I disagree. Europe has a very high rate of violent crime, including quite a few deadly attacks on jews.
In Q4 2023, BYD became the world’s largest electric vehicle (EV) manufacturer, passing Tesla in world wide sales. They mostly sell in China, and claim to make a profit while selling cars for about half the price of a Tesla. They also make robots, trucks, busses, smart phones, and batteries — including blade batteries that Tesla uses for a variant in its Berlin facility. They are a darling of the wall-street experts, in part because Warren Buffett is an investor. BYD cars look to be about as nice as Tesla’s at least from the outside and sell (In China) for a fraction of the price. The experts are convinced enough to write glowing articles, but I suspect that the experts have not invested, nor bought BYD products. — What do I know?
BYD truck. It looks good on the outside. Is it competition?
Part of the BYD charm is that it is considered socially progressive, while Tesla is seen as run by a dictatorial villain. A Delaware judge who concluded that Musk did non deserve the majority of his salary, and confiscated it. There are no such claims against BYD. BYD also has far more models than Tesla, 41 by my count, compared to Tesla’s 4. The experts seem to believe that all BYD has to do is bring their low-cost cars west, and they will own the market. My sense is that, if that was all they needed, they’d have done it already. I strongly suspect the low cost cars that are the majority of BYD’s sales are low quality versions — too low to sell in the US. Here are some numbers.
Total number of vehicles made 2023: Tesla: ~1,800,000 BYD: ~3,020,000 (1,570,000 BEV)
Net Profit 2023: Profit per employee: Profit per vehicle: Tesla: ~$9.5B (9.7%). Tesla: $67,857. Tesla: $5,280. BYD: ~$3.5B (4.1%). BYD: $5,542. BYD: $1,160
Market share based on sales in western countries 2023: Tesla: US: 4%, EU: 2.6% BYD: US: 0%, EU: 0.1%
The most telling comparison, in my opinion, is BYD’s tiny market share in western countries. Their cars sell for 1/2 what Tesla’s sell for. If their low-cost cars were as good as Tesla’s, there is no way their market penetration would be so low. My sense is that the average BYD vehicle is lacking in something. Maybe they’re underpowered, or poorly constructed, unsafe, or unreliable: suitable only for China, India, or other poor markets. I suspect that the cars BYD sells in Europe are made on a separate line. Even so, customers say that BYD cars feel “cheap.” BYD charges more for these cars in Europe than Tesla charges for its top sellers, suggesting that these vehicles are of a different, better design. Even so, the low numbers suggest that BYD does not turn a profit on the sales. I suspect they do it for PR.
Both cars look sporty. Why doesn’t the BYD sell?
Another observation is that BYD produces 5.03 vehicles per worker, per year. That’s half as many as Tesla workers produce per worker-year. It’s also about half of Ford’s Rouge plant (Detroit) worker production in the 1930s. That Ford plant was vertically integrated starting with raw materials and outputting finished cars. This low output per worker suggests that BYD is built on low wage, low skill production, or equally damning, that none of these models are really mass-produced.
A first world market favors a polished product that your mechanic is somewhat familiar with. That favors Tesla as it has significant market penetration, and a network of mechanics. Also, Tesla has built up a network of fast charge stations and reliable service providers. BYD has no particular charging infrastructure and virtually no service network. Charging price and experience is a key decider among first world customers. No American will tolerate slow charging in the snow at a high price — especially if they must travel to a charger without being sure the charger will be working when they get there. Tesla has figured out how to make charging less painful, and that’s worth a lot.
Tesla might fail, but if so I don’t think it will be because of BYD success. Months ago the experts assured us that cybertruck would be deadly a failure. I disagree, but it might be. I don’t think BYDs will be better. Government subsidies have ended in many states and countries (Germany, California…) putting a dent in Tesla sales, and they are having manufacturing difficulties, particularly with batteries. These seem fix-able, but might not be. I see relatively little first world competition in the US EV market from legacy auto companies. Maybe they know to avoid EVs. They currently make decent products, IC and EV, but lose money on every EV. They treat EVs as a passing fad. If they are right, Tesla and BYD will fail. If they are wrong, Tesla will do fine, and they may not be able to make up their lost place in the market. As for BYD, given their low production numbers, they will need some 3 million new workers and many new factories. I don’t think they can find them, nor raise the money for the factories.
Most of the data here was taken from @NicklasNilsso14. All of the opinions are mine.
