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jws

12,720 karma · joined January 18, 2008

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jws··on Plan to incinerate soil from Ohio train derailment is ‘horrifying’, says expert
Burning random manufactured stuff makes dioxins. It would be astonishing if there weren't dioxins in the soil before the accident and some more after it.

This being the rural United States, burn barrels for household waste were a thing for most of a century and spewed dioxin and a lot of other stuff all over the place. You can find lots of studies for background levels of dioxin.

It isn't a binary "Is there dioxin?" There certainly is. The question is, is it elevated above background? Is it elevated about established safe levels? If you run it through that nearby incinerator, will the dispersed plume raise land above acceptable levels?

The EPA has experience with dioxin sites and incineration. They bought a town of 800 people, demolished everything, hauled all the surface dirt to a site-built incinerator and over the course of a year incinerated everything and built a mound out of it. The locals were vocally aggrieved that the incineration was done near them. Its now a nice park for bicycle riding on flat land by a river.

jws··on Making a terrarium with an Arduino-powered artificial sun
It looks like the author is changing the light color and intensity throughout the day to approximate the color of sunlight. But he has a bunch of LEDs in different spatial locations…

You could make the LEDs be different colors based on location to model the light coming from that direction, at that time of day. Then you could get your plants to track.

It might take much brighter LEDs, since the relatively few sunward ones would need to really crank out the photons while most of them were more chill and bluer.

jws··on Vacuum Balloons (2020)
Also, maintaining vacuum is probably easier in larger units since the volume is increasing faster than the surface area. More gas intrudes, but there is much more space for it to intrude.

The wildcard is what has to change for the thickness of the shell as it scales. That either makes it work, or be infeasible. More research required.

jws··on Vacuum Balloons (2020)
I just checked out a couple videos of hydrogen filled party balloons being lit. I think it’s safe to say it could be a pants wetting experience and likely ignite paper party decorations.
jws··on U.S. FAA closes some airspace in Montana for Defense Department activities
That's a lot of text obscuring "we might decide to kill you, and that will be just fine". I might have even moved that up above "we might fine you".
jws··on Guinea worm disease reaches all-time low
One phase of the lifecycle only happens in humans and dogs. Once no one (or their dog) has it, then the cycle is done. The out-of-human part is three phases of larva which take a few weeks, although I didn’t see how long the phase 3 larva could persist without a human or dog host to proceed to adulthood.

https://www.cdc.gov/parasites/guineaworm/biology.html

jws··on Ask HN: Something you’ve done your whole life that you realized is wrong?
If when you coil a long cable or hose you find yourself fighting a twist as you coil… then you should learn to coil in an alternating overhand/underhand style. Google a video. Basically when grabbing the next hunk of cable you alternate between your thumb pointing away from you down the cable and your thumb point back up the cable to you and things just sort of happen right.

When you uncoil the cable it will be laying flat on the ground with no twists.

An alternative for massive cables it lay it out in a figure 8 on the ground. That will also pay out without twists.

Extension: The upright vacuum cleaner you've been using that releases the cord from the handle by twisting the top hook down? If it is leaving you with a twisted mess of cord, that means you haven't been winding it up in a figure 8.

Even more, since you got this far: Do this with your short cables too. Your USB and audio cables will last longer. When you have a twisted cable, a torque shows up at each individual wire where it meets its connector. The repeated twisting and untwisting leads to connection failure.

And when you get a new cable that is rolled up (any Apple cable), unroll it instead of pulling the ends apart. Then you cable need never have twists put into it.

jws··on Weather Machine – Rock solid weather APIs with zero hassle
It speaks poorly of an industry if there is a market for a toll gate to mush things into a common format.

It appears the plan with pricing doesn't include the weather data, just the transformation. You still need keys to the ultimate source.

I do feel the pain though. I moved to WeatherKit REST API when they stopped Dark Sky. The tiny amount of calls I make were free and easy in Dark Sky. In WeatherKit it is still free, but I had to figure out how to have my server generate JWT tokens which is a grade 2 pain in the ass on the 0 to 10 scale. (Also, the APIs are still marked as "beta". If you are killing a service and replacing it with a new one, maybe nail down that new one before cut over day? They are also sadly vague, the kind of stuff a programmer jots in because comments are required. If there is 3mm of rain followed by 50mm of snow, what does the precipitationAmount field have? The documentation says "The amount of precipitation forecasted to occur during the day, in millimeters.". Thanks, 12 words to tell me nothing. )

jws··on CamelCase vs. underscores revisited (2013)
Neither are the upper case letters or the underscore. Those are all composed with multiple keys. Easy enough to carve one out for the new separator.
jws··on CamelCase vs. underscores revisited (2013)
This has remained unsettled for 60 years. Perhaps we need a new choice?

How about Unicode "Thin Space" 0x2009 for a legal identifier character? (HN isn't letting me put the Thin Space in there.)

How about Unicode "Middle Dot" 0x00B7 for a legal identifier·character?

Best if you aren't in a fixed with editor for those.

I used middle dot in an experimental language which was Unicode heavy so already didn't like fixed width fonts. It parses trivially and reads well.

I haven't tried the thin space in earnest, but the example code I typed up looked reasonable.

jws··on Surveillance Footage of Tesla Crash on SF’s Bay Bridge
I haven’t looked at my tail lights, but in the US most cars have used the same bulb for hazard and brake. So the bulbs are already fully illuminated.

Cars meant for the rest of the world have separate yellow lights in back and you could flash those. I think they are adding a rapid burst flash for alert with those.

jws··on Surveillance Footage of Tesla Crash on SF’s Bay Bridge
Unless they are going under 13mph, two car lengths is too close.
jws··on Surveillance Footage of Tesla Crash on SF’s Bay Bridge
e.g. driving a couple of miles at moderate speed until there's a safer pull-off opportunity

I'm fairly certain this isn't a legal option in the United States. That would be unattended self driving.

It's probably a better solution, it just isn't available.

jws··on Animal Sedative Mixed with Fentanyl Brings Fresh Horror to US Drug Zones
Actually… kind of common in parts of Kentucky. My son in law arranged for us to buy a gallon to subdivide for gifts. Guy showed up with moonshine in the trunk. This is rural Kentucky, so you can't just have a transaction, you have to talk and be social for a period of time. So the seller brought out the AR15 from the trunk and there was some drinking, talking, and can shooting in the hollow… then we bought and paid and he was off to the next customer.

It came in a gallon water jug, like you would buy water in a grocery store. Ultimately I think that was its demise. When I went looking for it to subdivide I couldn't find it. But I had used a gallon of spring water to prime a well, I suspect I grabbed the wrong jug and primed the well with moonshine. The previously clear well kept producing a cloudy material that year.

No great loss, it isn't a "fine drinking" product. They make it from sugar since that's cheaper and cleaner. It's very much a "get you drunk cheap" product.

jws··on CDC File Transfer
To elaborate, rsync chunks in fixed sizes, so inserting or deleting a few bytes makes all different chunks from that point onward.

If instead you chunk based off of local content (conceptually like chunking text into sentences at periods, but its a binary thing on has an upper size limit and lower size limit and I couldn't find the algorithm specification) so that after an insertion or deletion in a small number of bytes you start getting the same chunks as before.

This drastically reduces the cost of identifying unmodified chunks.

jws··on Apple headset leak reveals new details and confirms earlier rumors
The initial target is developers who think they can build successful AR software for when the price comes down. You will not have significant numbers of users without compelling applications. $3k is a pittance in the scheme of creating a ground breaking application in an unexplored space.

$3k keeps the limited units out of drawers and in the hands of people that will be making something with them.

This device has a lot of cameras and scanners in it. After they work out what is actually required and used the consumer model may have fewer to control cost.

Apple will deliver an app or two to set the user experience quality bar, it sounds like VR conferencing is one of those, but that doesn't mean they think that is what the device is for. It is just that they need to give an example of what the user experience should be or you will have developers delivering poorly performing, battery eating, usability disasters and customers will think that is inherent to the device.

jws··on The State of HTTP in 2022
I've implemented PAT on a service. A server would only want to require PAT when it wants to see if it is dealing with a human. In the context of, say a blog, you would require PAT when someone wants to make an anonymous comment or create an account.

For requests which are "reading" you just serve content, unless for some reason you only want human eyeballs to see your content.

In your proposed scenario, reading the publicly accessible contents of the web, there should be no problems. (Of course some percentage of sites will accidentally have required PAT at any time and be unscannable, but presumably they figure that out and fix it.)

Now for the good side: I, reluctantly, implemented a geolocation filter to control anonymous content additions to that service I was alluding to. I felt bad about it, but I also felt bad having to filter out content spam every day. It turned out that all my strange content spam came from one country, so I banned 143 million people from anonymous content creation for my convenience.

With PAT I can remove the national ban and let any "probably human" in.

jws··on Tesla driver falls asleep – Autopilot ignores police and continues driving
"The driver had apparently tricked the car's safety systems. … In the footwell of the car, the officers found what is known as a steering wheel weight … A preliminary investigation into the criminal offense of endangering road traffic was initiated against the Tesla driver."

Sounds more like the driver defeated the safety systems which stop the vehicle if the driver is incapacitated.

jws··on Ventura Issues
External drives still take minutes to mount or sometimes never mount automatically. Sometimes I can manually mount them from Disk Utility. Other times I need to reboot or disconnect other drives first.

I've encountered failing USB disks which appear to work fine on macOS, but suddenly operations take minutes to perform and can block operations system wide. They don't report errors, and they don't show as CPU use in any program, but everything on the system slows to a crawl when you hit sensitive spots on the disk.

It's worth removing external storage devices and adding them back one by one any time you have a hanging or slow Mac to diagnose.

Apple hates to scare or confuse users, but if a disk drive is taking a four orders of magnitude more time to do operations than it used to, I'd like my computer to please let me know.

jws··on Americans duped into losing $10B by illegal Indian call centres in 2022: report
Terrorism requires a political goal. Simply wanting more money and stealing it isn't a political goal.
jws··on King Charles' first Christmas speech reflects cost-of-living crisis
Looking at the current estimates from the UN, if you completely liquidated the British monarchy and got good value for all the seized assets, you could feed the hungry for 6 months.
jws··on HelloSilicon – An introduction to assembly on Apple Silicon Macs
The Apple ABI has requirements not present in the generic ARM.

https://developer.apple.com/documentation/xcode/writing-arm6...

jws··on The cold hard truth about electric vehicles in winter
my diesel car had no big problems with -19°C

It depends on the formulation of your diesel. If you had a tank of "summer diesel" it would be gel at that temperature. Generally the supply chain starts changing the formulation as the weather gets colder and everything is good until you get to arctic temperatures. But if you fill up at a station that doesn't sell a lot of diesel and they still have summer diesel and its an early cold spell, or you are driving a vehicle you don't fill often, you can be in trouble. There are also additives you can add on your own if you know you have summer diesel.

jws··on The cold hard truth about electric vehicles in winter
Spoken by someone who's never had their diesel fuel begin gelling in the fuel line at night on a frigid, remote highway and trying to figure out if you can make it to somewhere with heat before you stop completely. Then finding out they only have gasoline, so you try to figure out how much gas you can add to the diesel tank to keep it from gelling but still run adequately to move you along.

Sometimes we forget that we have 100 years of infrastructure behind our internal combustion engines and about 10 behind the electric vehicles.

In the first 10 years of internal combustion engines, you bought benzene at the local apothecary and used that to fuel your car.

Three years of EV in a more or less unheated garage and I'm still just charging off my 15A 120V outlet. It's fine. I plug in every other day or so. But you know what I don't do? Freeze my ass off standing in a gas station in subzero temperatures and howling winds! Not missing that at all.

jws··on Paper-Thin Solar Makes Any Surface Photovoltaic
Just because it gets distorted, not that it changes the message.

The solar panels installed on the White House during the Carter years were a solar hot water heater, not a photovoltaic system.

Here is part of his speech from the dedication ceremony in 1979: "In the year 2000 this solar water heater behind me, which is being dedicated today, will still be here supplying cheap, efficient energy…. A generation from now, this solar heater can either be a curiosity, a museum piece, an example of a road not taken or it can be just a small part of one of the greatest and most exciting adventures ever undertaken by the American people."

Details are not readily available without clearance, but the roof of the White House is a limited commodity and there was probably an antimissile system installed there after the solar panels. They might have needed the space.

Here in 2022 we can see which road was chosen. We didn't get to 20% renewables by 2000, but we are up to 12%, so making progress, if somewhat more slowly.

jws··on ‘My power’s low’: NASA’s Insight Mars lander prepares to sign off
With an atmospheric density 1/150th that of Earth, the engineering of a leaf blower might be tricky. Clearly the atmosphere can move dust, but you might hit speed of sound problems in your turbine.

Someone should spend a couple years doing some PhD work on Martian dust blowing turbine designs, but not burn out completely so they can write a 1000 word, interesting blog post with some pretty pictures for me to consume.

jws··on ‘My power’s low’: NASA’s Insight Mars lander prepares to sign off
Solar panel output is remarkably resilient to visible dirt. I have an installation on a seagull rookery. As you can imagine things get thoroughly “whitewashed”, especially since the top edge of the angled array is prime “standing around squawking and crapping” space. They can be covered to the point that there isn’t a clean spot the size of your fist anywhere on them and they will still be putting out 75% of their rated power.

I suspect it has something to do with the non-linear response of the human eye. You don’t have to reflect a lot of light to be perceived as significantly lighter than black, so diverting 25% of the light from the panel to reflected light makes the panel look quite light.

jws··on Winter & Cold Weather EV Range Loss in 7,000 Cars
The common RV battery for cold weather is a LiFePO4 battery. These can be used down to -20°C (-4°F), but you must not charge them below freezing, it will destroy the electrodes. The batteries integrate a heater which absorbs charging energy until the battery is safely warm enough to accept the charge, then charges normally.

In an EV this would be handled when charging by running a heater until it is a safe to accept charge. When driving, any time the battery becomes too cold you would divert regenerative braking energy into heating the batteries instead.

jws··on Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin
Acrylic and water have virtually the same index of refraction, so if the crack forms on the wet side of the wall and wicks in water you will not detect it visually.

It forms the basis of some magic tricks involving walking on or supporting things in water. (I say some, the rest are totally magic and you should enjoy them.)

jws··on Solar furnace to melt steel at 2000°C for Swiss recycler
The maximum efficiency of a steam turbine is just shy of 50%, by the time you have integrated the whole plant, 23-35% is typical. (so says wikipedia)

The sort of solar panels one would use in a large installation are around 23% efficient.

So they are close in "power/hectare". From there it is capital costs and cost of operation that will make the decision.

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