Well, a lot has happened since March 13th.
The "wash your hands and cover your cough" and do some mild social distancing campaign was too little too late. Heavy social distancing followed by shelter in place became the rule in a lot of places as the race was on to keep COVID-19 cases from overwhelming hospitals. Some place managed to get ahead of the curve and kept cases to a minimum, mashing the curve down - notably San Francisco and California. Some places get going too late and got swamped - notably Albany GA and NYC. The Atlanta area was in the middle. The metro counties got going a couple weeks ahead of the state and managed to keep the local hospitals afloat and use of the emergency overflow spaces to a minimum (so far...)
Watching all this play out so fast was horrific. Knowing how much worse it could have been was not much consolation. Hearing about the pain that places in the world that got going late, notably Italy, were going through was sobering enough to not think twice about obeying the shelter in place rules.
Helping my wife's 80+ y.o. parents, we doubled down on our social distancing, doing curbside for groceries and generally staying out of any buildings except our house. We still do takeout and delivery of restaurant food, trying to help keep economy going. Our grown kids, who live in the area, have done the same. They are helping our chances, and consequently, the in-laws chances of "keeping clean". I have to say, even doing that is stressful, remembering to wear a mask and wiping down stuff. Really, though, compared to what a lot of people are going through, that stress is really a "first world problem."
Anecdotal stories and statistics filled our news feeds and were handed down through friends and relatives. A lot of it was like waiting on a Tsunami, not knowing how high the wave would be.
Consuming so much news was confusing and stressful. There is so much not known that getting a clear picture of what to do, how to do it and what will happen was very difficult. "The virus can 'live' 72 hours on surfaces". "The virus was found on a cruise ship two weeks after everyone was off." "There is plenty of testing." Friends with symptoms can't get tested. It's only airborne droplets that are contagious. Aerosols can travel 30 feet. It could be on you shoes. This person has it. That person died. Only older people with co-morbidity get the severe form of the disease. A young, healthy person died. Lots of kids get it and are asymptomatic. Are they "carriers" or not? Drug treatments are being tried. They help! They are worthless! They aren't being tried the right way!
Usually, more information is better and reliable information is the best. With this thing, so much is unknown, or known imperfectly, that speculation, conspiracies and misinformation fill the void at a great rate. It felt like this: https://www.instagram.com/tv/B_PrvZdhMiR/?igshid=yumazu0pfnn5
Using Twitter news feeds is normally helpful, but there is just too much and whole day of it will sink your psyche, so I've tried, mostly unsuccessfully, to limit my Twitter time.
One source of information I've found most useful and enlightening is a woman who blogs on Facebook. Her "about": ".... a pathologist with degrees in infectious disease epidemiology, mathematical modeling of epidemics, and fieldwork in epidemic control." In other words, she's a subject matter expert. Here's a link https://www.facebook.com/jenniferkastenmd/
So, after the first couple weeks, we've kind of settled into a new routine. What does that look like? What's surprising, interesting, annoying? What's keeping us busy?
That'll be the next blog posts.
Monday, April 27, 2020
Friday, March 13, 2020
Hub and Spoke. Be a hero to someone you don't know.
Is this an blog on hub and spoke vs. lane transportation operating philosophies? No. This is about everyone's favorite topic, Coronavirus, and the problem with it.
The problem, generally, isn't that it's so deadly or horrible to survive for most people. So, why not just let everyone get it and get over it and be done with it? The problem is how fast the infection spreads and what that means for our health care system and patients who need it. If we just let things happen, the 10% or so that need hospitalization for a while will swamp our "right sized" healthcare industry. We don't have enough beds, doctors and ventilators to cover even a fraction of what would be needed if we did that. That means a lot of folks would die unnecessarily. What to do, then? In general, we need to "flatten the curve".
https://www.statnews.com/2020/03/11/flattening-curve-coronavirus/
For the more "math-y" https://medium.com/@tomaspueyo/coronavirus-act-today-or-people-will-die-f4d3d9cd99ca
How to flatten the curve? Have fewer spokes. Make your spokes skinny.
If you think of yourself as a hub that is connected to the other people you come in contact with as spoke, and draw that picture out with each person you are connected to as having a spoke with each person THEY are connected to and so on, you can see that if each person has a lot of spokes, then you don't have to go out too far until you come to someone who has coronavirus. Fewer spokes, you have to go out more "levels" until you reach and infected person.
If you then think about each spoke as a conduit for likely transmission, then you can draw that spoke as a fat pipe if it's close contact and skinny if it's a less likely path for transmission. Somebody you sit next to at work - fat pipe. The person who stocked those black beans you bought at Kroger this morning - skinny pipe. So, the goal is to have less spokes and make each spoke as skinny as possible.
If you think about indoor places with hard surfaces that have lots of traffic - airports, mass transit vehicles, grocery stores - and you know that the virus can stay viable on hard surfaces for a couple of days - you then have lots and lots of skinny spokes to lots and lots of people who have touched that surface or item or coughed on it in the past couple days.
If you think of each day as its own diagram, then overlay each day on top of the other, you can see that repeated contact with the same people is not as risky as contact with different people each day.
Right now, each infected person is infecting over two other people. That's what causes the geometric growth of cases. If you want the number cases to stop growing, you have to get that transmission number under one. You do that by cutting the number and width of the spokes between each of us.
The problem isn't whether you or I will have a rough time with the disease. Odds are, we won't. But, out "sized for normal circumstances" health care industry can't handle a sure the size of what this virus did to China and now Italy. Places that have "flattened the curve" have death rates of 1% or less because it doesn't overwhelm their health care system Places that are overwhelmed have much higher death rates.
And, each of us trying to cut or shrink our spokes to others we contact doesn't just affect us, but everyone they have spokes to, and those people, and on down the line.
How do you reduce and shrink your spokes? Tons of ideas here: https://www.cdc.gov/coronavirus/2019-ncov/community/index.html
But, remember this doesn't mean you have to lock yourself in a closet! There are lots of low risk, skinny spoke things you can do. Go for a drive. Go for a hike. Go bicycling. Gardening. Go camping. Play tennis and golf. Play cards with your friends. Go to the botanical gardens. Go railfanning. (of course!). Get back into your hobbies and crafts. Go to the beach. Get to those procrastinated house projects. Make a photobook of your last trip. Go shopping - on Amazon. Plan your next trip (this problem IS going to be solved - it's just how much pain we have to go through...and how long it will take) Learn a new language or calculus (huh?)
So, it's not about us. It's about all of us. Pay attention to your spokes! The life you save may be your friend's co-workers son's mother-in-law.
The problem, generally, isn't that it's so deadly or horrible to survive for most people. So, why not just let everyone get it and get over it and be done with it? The problem is how fast the infection spreads and what that means for our health care system and patients who need it. If we just let things happen, the 10% or so that need hospitalization for a while will swamp our "right sized" healthcare industry. We don't have enough beds, doctors and ventilators to cover even a fraction of what would be needed if we did that. That means a lot of folks would die unnecessarily. What to do, then? In general, we need to "flatten the curve".
https://www.statnews.com/2020/03/11/flattening-curve-coronavirus/
For the more "math-y" https://medium.com/@tomaspueyo/coronavirus-act-today-or-people-will-die-f4d3d9cd99ca
How to flatten the curve? Have fewer spokes. Make your spokes skinny.
If you think of yourself as a hub that is connected to the other people you come in contact with as spoke, and draw that picture out with each person you are connected to as having a spoke with each person THEY are connected to and so on, you can see that if each person has a lot of spokes, then you don't have to go out too far until you come to someone who has coronavirus. Fewer spokes, you have to go out more "levels" until you reach and infected person.
If you then think about each spoke as a conduit for likely transmission, then you can draw that spoke as a fat pipe if it's close contact and skinny if it's a less likely path for transmission. Somebody you sit next to at work - fat pipe. The person who stocked those black beans you bought at Kroger this morning - skinny pipe. So, the goal is to have less spokes and make each spoke as skinny as possible.
If you think about indoor places with hard surfaces that have lots of traffic - airports, mass transit vehicles, grocery stores - and you know that the virus can stay viable on hard surfaces for a couple of days - you then have lots and lots of skinny spokes to lots and lots of people who have touched that surface or item or coughed on it in the past couple days.
If you think of each day as its own diagram, then overlay each day on top of the other, you can see that repeated contact with the same people is not as risky as contact with different people each day.
Right now, each infected person is infecting over two other people. That's what causes the geometric growth of cases. If you want the number cases to stop growing, you have to get that transmission number under one. You do that by cutting the number and width of the spokes between each of us.
The problem isn't whether you or I will have a rough time with the disease. Odds are, we won't. But, out "sized for normal circumstances" health care industry can't handle a sure the size of what this virus did to China and now Italy. Places that have "flattened the curve" have death rates of 1% or less because it doesn't overwhelm their health care system Places that are overwhelmed have much higher death rates.
And, each of us trying to cut or shrink our spokes to others we contact doesn't just affect us, but everyone they have spokes to, and those people, and on down the line.
How do you reduce and shrink your spokes? Tons of ideas here: https://www.cdc.gov/coronavirus/2019-ncov/community/index.html
But, remember this doesn't mean you have to lock yourself in a closet! There are lots of low risk, skinny spoke things you can do. Go for a drive. Go for a hike. Go bicycling. Gardening. Go camping. Play tennis and golf. Play cards with your friends. Go to the botanical gardens. Go railfanning. (of course!). Get back into your hobbies and crafts. Go to the beach. Get to those procrastinated house projects. Make a photobook of your last trip. Go shopping - on Amazon. Plan your next trip (this problem IS going to be solved - it's just how much pain we have to go through...and how long it will take) Learn a new language or calculus (huh?)
So, it's not about us. It's about all of us. Pay attention to your spokes! The life you save may be your friend's co-workers son's mother-in-law.
Saturday, January 11, 2020
Electric Cars and Climate Change
If you have been paying attention to climate change news, you might think the push toward electric cars is being driven by a desire for CO2 reduction. After all, transportation is responsible for slightly less than 1/3 of CO2 emissions.
https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions
I disagree. Not the CO2 emissions part. The "what's driving the change" part...
Electric cars are becoming available because technological advances have made them practical and economic.
The two big advances are solid state power conditioning and battery chemistry and construction. A third would be low cost computing to monitor and control everything.
Over the past few decades, switching power supplies and inverters have allowed power of just about any kind to be transformed into any other kind. Some examples:
Your car has a 12 volt battery and you want to run a 120 VAC device from it. Decades ago, you would have had to buy a motor-generator set with a 12VDC motor driving an AC generator to convert the 12 VDC power to 120VAC, 60Hz power. They existed but were bulky, expensive and impractical in most cases. Now, you just need to buy an inverter. Some cars even come with them built in. They are 100% solid state, small, lightweight and cheap.
Microwave ovens used to be very heavy and relatively low power because they needed large transformers with heavy iron cores to convert power to feed the magnetron.
"Wall-wart" power supplies used to be fairly large affairs because they had small transformers in them.
Now, they have solid state switching power supplies that not only make them much smaller, but able to run on multiple power inputs.
Electric cars use robust AC motors that can vary their speed and torque be feeding them variable frequency AC power made possible by relatively cheap, solid state power conditioning.
Batteries have come a long way. When I was a kid, batteries were carbon-zinc and weren't rechargable. A couple of D cells would last only a couple hours in a flash light. Barely long enough for a good game of flashlight tag. Then came alkaline batteries, then Ni-cad rechargeables, then Nickel-metal hydride, and now Lithium-ion.
They have really high power density and can be pretty fast charging.
If you couple these batteries with the solid state power conditioning and control it all with a microprocessor, you have the formula for a successful electric car.
That's fine, but what makes an electric car "better" than a gas of diesel powered one? Two things. Far fewer moving parts. Drastically improved energy efficiency.
Consider the number of moving parts in and engine and transmission - hundreds. Compare that to the number of moving parts in and AC motor - a dozen or so (the rotor, plus the roller bearings to support the rotor's shaft.) Consider the cost to manufacture, machine and assemble an engine and transmission alone. Then add in the complexity of the systems to keep the engine and transmission running - oil pumps, oil changes, etc. Electric propulsion is a clear winner because it's far, far simpler.
Efficiency? Internal combustion engines are heat engines. At full speed and load, an automotive diesel engine can be about 40% efficient, a gas engine about 30% efficient. Laws of thermodynamics regulate this. But, we don't run our car engines at full speed, full load. We run them slower and throttled nearly all the time. Efficiency under these conditions is much worse - perhaps half - thermodynamics, again.
Electricity can be generated from coal fired power plants at 40% efficiency, from combined cycle natural gas plants, at 60% efficiency. Solar and wind have zero fuel cost. Power line losses are typically around 8-15%, so that combined cycle gas power plant delivers electricity to the outlet at roughly 55% net efficiency. The round trip to charge and discharge an Li-ion battery is around 99% - almost negligible. So, where your car is running at 15% net thermal efficiency from a petroleum fuel source, an electric car will be running at over 50% net thermal efficiency from a petroleum fuel source. If your car gets 20 mpg, an identical electric car would get nearly 70 mpg.
An electric car has some other benefits as well.
Better performance. The battery and electric motor can supply full HP over the car's entire speed range. This means mind numbing acceleration at low speed. An internal combustion engine HP varies with speed. A transmission is needed to match engine output to vehicle demand.
Reduced maintenance. No oil changes. No spark plugs. Regenerative braking means fewer brake jobs.
Longer lifespan. With no engines and transmissions to wear out, electric cars can be expected to have much longer lifespans. Some early Tesla fleet owners have gotten over 500,000 miles out of them with few major failures. This will only improve as the state of the art advances.
Technological advances have made electric cars practical replacements for internal combustion powered automobiles. They will only get better and cheaper as the technology continues to mature and evolve. This was happening regardless of climate change, although the rate of change may be accelerated because of it.
All the major auto manufacturers are committed to electric cars. Not because they want to be "nice". But, because they are better.
https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions
I disagree. Not the CO2 emissions part. The "what's driving the change" part...
Electric cars are becoming available because technological advances have made them practical and economic.
The two big advances are solid state power conditioning and battery chemistry and construction. A third would be low cost computing to monitor and control everything.
Over the past few decades, switching power supplies and inverters have allowed power of just about any kind to be transformed into any other kind. Some examples:
Your car has a 12 volt battery and you want to run a 120 VAC device from it. Decades ago, you would have had to buy a motor-generator set with a 12VDC motor driving an AC generator to convert the 12 VDC power to 120VAC, 60Hz power. They existed but were bulky, expensive and impractical in most cases. Now, you just need to buy an inverter. Some cars even come with them built in. They are 100% solid state, small, lightweight and cheap.
 |
| An older inverter. New ones are more powerful and cheaper. |
Microwave ovens used to be very heavy and relatively low power because they needed large transformers with heavy iron cores to convert power to feed the magnetron.
"Wall-wart" power supplies used to be fairly large affairs because they had small transformers in them.
 |
| This thing makes 24VAC from 120VAC to power a doorbell. |
 |
| Everyone knows what this is. You can use it all over the world with only a plug adapter. |
Electric cars use robust AC motors that can vary their speed and torque be feeding them variable frequency AC power made possible by relatively cheap, solid state power conditioning.
Batteries have come a long way. When I was a kid, batteries were carbon-zinc and weren't rechargable. A couple of D cells would last only a couple hours in a flash light. Barely long enough for a good game of flashlight tag. Then came alkaline batteries, then Ni-cad rechargeables, then Nickel-metal hydride, and now Lithium-ion.
They have really high power density and can be pretty fast charging.
If you couple these batteries with the solid state power conditioning and control it all with a microprocessor, you have the formula for a successful electric car.
That's fine, but what makes an electric car "better" than a gas of diesel powered one? Two things. Far fewer moving parts. Drastically improved energy efficiency.
Consider the number of moving parts in and engine and transmission - hundreds. Compare that to the number of moving parts in and AC motor - a dozen or so (the rotor, plus the roller bearings to support the rotor's shaft.) Consider the cost to manufacture, machine and assemble an engine and transmission alone. Then add in the complexity of the systems to keep the engine and transmission running - oil pumps, oil changes, etc. Electric propulsion is a clear winner because it's far, far simpler.
Efficiency? Internal combustion engines are heat engines. At full speed and load, an automotive diesel engine can be about 40% efficient, a gas engine about 30% efficient. Laws of thermodynamics regulate this. But, we don't run our car engines at full speed, full load. We run them slower and throttled nearly all the time. Efficiency under these conditions is much worse - perhaps half - thermodynamics, again.
Electricity can be generated from coal fired power plants at 40% efficiency, from combined cycle natural gas plants, at 60% efficiency. Solar and wind have zero fuel cost. Power line losses are typically around 8-15%, so that combined cycle gas power plant delivers electricity to the outlet at roughly 55% net efficiency. The round trip to charge and discharge an Li-ion battery is around 99% - almost negligible. So, where your car is running at 15% net thermal efficiency from a petroleum fuel source, an electric car will be running at over 50% net thermal efficiency from a petroleum fuel source. If your car gets 20 mpg, an identical electric car would get nearly 70 mpg.
An electric car has some other benefits as well.
Better performance. The battery and electric motor can supply full HP over the car's entire speed range. This means mind numbing acceleration at low speed. An internal combustion engine HP varies with speed. A transmission is needed to match engine output to vehicle demand.
Reduced maintenance. No oil changes. No spark plugs. Regenerative braking means fewer brake jobs.
Longer lifespan. With no engines and transmissions to wear out, electric cars can be expected to have much longer lifespans. Some early Tesla fleet owners have gotten over 500,000 miles out of them with few major failures. This will only improve as the state of the art advances.
Technological advances have made electric cars practical replacements for internal combustion powered automobiles. They will only get better and cheaper as the technology continues to mature and evolve. This was happening regardless of climate change, although the rate of change may be accelerated because of it.
All the major auto manufacturers are committed to electric cars. Not because they want to be "nice". But, because they are better.
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