onetimeuse92304

That is unfortunately my reality working with other Java developers. I mean, it would be if it actually wasn't even worse than that.

They are constantly pushing to create more "microservices" which is just just a misguided trend to spread your functionality over as many machines as possible and have your user wait until a graph of a hundred network calls finishes to get any simplest thing done.

Then they spend huge amount of time trying to resolve performance issues and call me, a "performance expert", to try to help find ways to improve the situation. Then dismiss my calls to maybe modularize their applications using regular programming language mechanisms like interfaces and packages.

Anyway... it's been quite long since I met a Java dev who even knows what MMU and TLB is. It's a rare candidate who knows what is a virtual memory in the first place.

It is hard to know the difference between efficient, frugal and cheap. Your employees will always want to spend more money, you always want to save it. You may not be expert on the topic of servers but you also know you can't completely trust your employees.

It is a difficult situation for owners and sometimes they do mistakes.

Was he doing something illegal/immoral?

Maybe he had two Ferraris because he was frugal with his business?

Why does everybody think it is absolute must to maximise the profits? Maybe he was ok with his profits and just didn't care to optimise his business as long as he has comfortable life? Is there something wrong with it.

Over the years I have worked as an advisor with many owners and CEOs of various sized companies (up to couple thousand employees). I had many situations when those CEOs would confide in me how disappointed they were in some of the decisions their employees made when it comes to finances. Especially high level leaders, who should know better. As a rather typical example, situation when an ex-Microsoft director hired as new IT director would sign a contract with Snowflake to commit 300k USD over 3 years for a 10% discount. The issue is I calculated if we did not commit, we would actually pay about 500 USD/year. Yes, not 500 thousand, just 500 USD. After that we have instituted a near total ban on commitments as a recognition of the fact that we just can't predict the future.

Or people that would start some expensive stuff on AWS and then would just "forget" to turn them off. Or a guy who thought it is ok to pay almost $100k for a marketing stunt where they would livestream with a single webcam a bunch of grazing cows for a week.

Yeah, it is kind of easy to waste money when it is not your money.

I am (an amateur) sailor and every time I have a new crew I go through the same set of safety rules with them including explanation of what to do in case somebody falls overboard.

We will usually also go through a training exercise (throw a weighted fender into water while underway) to cement the lesson a bit and for people to understand what they can expect in a real situation.

Probably the most important task is that of the person who needs to keep pointing with the finger at the man over board and keep constant focus on not loosing them from their sight.

On a small yacht and with any waves around you, it is almost impossible to find a bobbing human head unless somebody is constantly focused on tracking the victim. Trust me, once you loose the sight of the head that only shows in your view intermittently, it can be almost impossible to find them again.

I am not a mountaineer, but I have red quite a bunch of mountain stories and the same theme repeats all over again -- people who die even though they could be easily rescued if just anybody knew where they got stuck. People who got caught by a blizzard and got disoriented even as close as a hundred feet from the basecamp. Rescuers going on a long and dangerous rescue mission even if the victim was almost at the door step. Rescuers risking their lives even though the victim have fallen from a great height and there was essentially no chance for a positive outcome. Rescuers waiting for a long time not knowing what to do and trying to weigh the risks of going out vs the risk to their friend who did not report to the base at the planned time.

A simple GPS device could cut so much of that drama just like a simple mobile phone cut a lot of drama from meeting with somebody. Who still remembers the time when you had to meet with the other person at the prearranged time and if they were not there you faced a sometimes difficult decision to stay and wait because they might be late or go back home?

As to the GPS receiver inaccuracy, even with inaccurate results the signal can be useful. You can usually tell if the signal is or is not accurate by how erratic it is. If it follows the planned path it probably is accurate. If suddenly strays off the planned path and then stays in one place while still transmitting -- that is very likely a sign of accident. Even if you don't have 100% certainty in the signal, rather than search everywhere for the victim and risk rescuers' lives, you can just go where the signal points and there is good likelihood you will not come emptyhanded.

> I cannot explain the physics

Here, this is actually the problem.

Water can store many times the amount of energy per volume or mass, per degree Celcius, than rock.

What you see is that rock has much lower thermal conductivity. It can be hot inside but it is not as good at transferring that heat outside. It means when you have hot rock it will stay hot for longer than equivalent amount of water. That because water emits that energy faster.

But put that rock and water in a well insulated vessel and you will find that the properties of the insulation and the vessel will start dominating the process and what counts now is how much energy you can store in the material inside.

> -Order of magnitude smaller coefficient of thermal expansion.

On the other hand the thermal expansion of water does not matter because water, you know, is a liquid -- it conforms to whatever vessel you put it in.

> -No real risk of phase change - freezing or boiling.

In a vessel that is meant to store thousands of tonnes of water that is hot and that is very well insulated to store energy for months, there is no real danger that the water will freeze. On the boiling side, water make it easy to monitor the temperature and you just stop adding energy if it starts boiling. Your kettle can do that reliably, we can do this for a huge battery.

> No problems with corrosion/scale in high temperature

It is hard to put 5 thousand tonnes of sand in a container and ensure it is dry. There is always going to be water that will be evaporating when you heat the sand in the middle and condensing on the sides that are cold.

There is no possibility of scale when you do not heat water to boiling.

> Sand is great because it's largely inert in a huge range of temperatures.

Crushed rock will release water when heated up.

100MWh = 3.6 * 10^11 joules

sand's heat capacity = 830 J/kg degree C

sand battery size is "13m tall and 15m wide". Assuming most voluminous possible shape that's 13m * 15m * 15m = 2925 cubic meters of sand (100% fill, no account for insulation, etc.)

Dry sand density is about 1600kg/m3

Total weight of sand would be 2925m3 * 1600kg/m3 = 4.7Mkg (4.7kt)

4.7Mkg of sand has a heat capacity of 830J/kg * 4.7Mkg = 3.9 * 10^9 joules / degree C (it takes this much energy to heat up entire battery by one degree C)

So from this, we get that 100MWh of energy would heat up the battery by (3.6 * 10^11 J) / (3.9 * 10^9 J/C) or about 100C.

If we include a different shape (a cylinder), and account for a thick insulation needed, this becomes closer to 200C of temp diff.

I guess it checks out... It is going to be more difficult to estimate heat loss.

But sand is quite expensive so my question is, why sand and not water? Water has 5 times higher specific heat per weight, about 3 times per volume. Water is way cheaper than sand and much easier to find, transport and extract energy from. The only real problem with water is you can only heat it up to 100C.

I think there is a great opportunity to use AI in design and development, as long as it is used correctly. Which is as tools to help engineers.

At my previous workplace I wrote a documentation bot which helps people find documentation based on vague descriptions of what they are looking for (like when you know you saw something but you don't know where exactly or what the keyword is). Or by specifying what you want to accomplish.

Mind, the bot would not create answers to questions, it would just ingest existing documentation and point people to things that are relevant to their searches.

All development was offshored to a lowest bidder. Thanks to this, all our critical flight control software is now developed by a single intern aided by Copilot (sic!) We are now looking for a way to optimize the intern away.

I did not mean doing home electrical work. That I do leave to professionals.

But there are times I have a device on my bench that is consuming 230V AC.

I have a 3kVA separation transformer set up, which makes it safer for me to work with the device (there is no potential between the DUT and the ground).

Technically, even without the transformer the residual current protection should kick in and prevent you getting killed between device and the ground. I have tested mine couple of times to check whether it works. But I somehow still feel better with a separation transformer.

But there is still the problem that I could touch different parts of the device that are at different potential and then I could get zapped this way. There is not much protection there. Solution -- If you must, don't ever touch more than one place at a time.

Well... one difference between a stun gun and CRT tube is that in a stun gun you usually have both terminals relatively close to each other. Little chance of the main pulse going deep across the chest. On the other hand working with the CRT you are likely using both hands and that makes the signal go through your upper chest, by default. So yeah, there is something to it.

One thing I learned as amateur EE is to always use just one hand to probe the device under test if there is any high voltage or AC involved. You put the other hand behind you so that there is no chance you create a short right through your chest.

> It's also a safety issue, since the Cathode voltage might be substantial.

When I was a small kid, my father had a TV set repair side hustle. I was 7-8yo but I would sometimes be called to help him a bit. Once he asked me to clean a bunch of CRT tubes from substantial amount of dust. What he forgot is that he was just testing one of them and the charge wasn't properly dissipated and it did not have time to dissipate on its own.

I got hit with a spark so powerful, that it must have temporarily disrupted my brain because for a brief moment I was completely stupefied, and then I just resumed cleaning it. Then I got hit for the second time, then for the third time. Only after third time I realised that me cleaning the tube has something to do with it. Probably the discharge was much less powerful the third time and did not stun me completely.

I can tell you the voltage and amount of charge on these things is no joke. Multiple tens of thousands of volts is enough to stun you temporarily. Probably not enough to cause lasting damage unless you are extremely unlucky about where the discharge went (stun guns usually have higher voltage and capacity), but enough for you to lose control of your body, fall and hurt yourself.

It is hard for me to understand WHY they spent so much time discussing the process and whether to record or not record it in CMES, but they could not be bothered to remember the truly important part -- to bolt the fucking thing properly.

It is a bit as if people forgot what their job is about.

As a mathematician we can easily confirm by going outside and waiting until we can see 19 people being visibly obese. Best see 19 obese people at the same time to eliminate possibility that some of them are the same person who just changed clothes and appearance to confuse the experiment.

Decades, in most cases. And not necessarily self-neglect. Frequently it is neglect by the parents or by your environment. Currently, in many countries it is pretty difficult to maintain healthy diet if you have below average income.

The way obesity starts in most cases is that you eat the wrong things for a long time and this slowly damages your internal regulation. There isn't super firm consensus on what exactly causes this to develop, but you can bet on low protein, high sugar high carb paired with low amount of exercise and food intake spread throughout the entire day (snacking).

Hyperpalatable food that is currently majority of food items in stores is essentially designed to keep people eating.

But it typically takes a decade or two for most people before they visibly gaining weight. For example, I drank 2-4 liters of Coca Cola every day and for over a decade I was completely fine. Until I wasn't and started gaining weight dramatically.

As far as I understand most (yes, over half) of kids in developed countries are already progressing into obesity and have damaged metabolism to higher or lesser extent. That they are not classified as sick and in need of help is only due to our medical system which essentially waits until you require medical assistance until you get classified as sick.

Only some people get fat because they overeat a lot for whatever reason. Some unfortunate kids because parents let them eat whatever they want. Some unfortunate adults because maybe they are stressed and overeat to compensate.

But most people really take a long time to develop the underlying condition that causes them to gain weight.

More likely helpful with perspiration and heat management.

It is absolutely OBVIOUS why there is no old forests in Netherlands. I don't think there is any danger of the same happening to the US.

US is 237 times larger than Netherlands. Netherlands also is 17.5M people. If US had the same population density, there would have to be over 4B people in the US.

And that is not including the area that Netherlands had to recover from the sea.

I don't think real requirements are known and understood in general.

For example, consider a team that has been maintaining the system for a long time. Most or all of the people that has initially created the system have moved on to other positions or companies. Many of the people who stuck with the team did so for reasons of being experts but are also unable or unwilling to communicate well (for example, because they see the value in preserving their position of being one of the few people with expertise).

In a team like that, they might have good memory of things they have worked on recently, but not necessarily things that are working and the users take for granted. Users do not typically spend much time reaffirming the features that are working well.

One of the challenges of working with stakeholders is that close to 100% of the communication tends to be on things that are not working or are missing or they want to get done. As a developer or manager of the team, you need to find some way of answering the question "am I doing well?". Because users are of course unhappy with how the application works, but to understand levels of unhappiness you need to find some other reference (working for some other projects).

I was yesterday in a meeting with developers where they complained about how manual our deployment system is.

Our deployment system requires them to press a button to deploy a version of the application to the environment. Yes, log in and press a button.

I explained, that I worked in the past for teams that had hundred page manuals on how to compile and deploy the software and that manual would be compiled again and again for each release and the process would take from couple of days to a whole quarter.

So you need to have some perspective to be able to judge that kind of feedback.

I think people tend to want to rewrite software for the psychological break from the old, bad and ugly thing they don't want to have anything to do with anymore.

It is so easy to think "If only I could start everything from scratch, life will be so beautiful and I will be so successful and everybody will be happy. I will fix all the problems of the current codebase and people will forever sing songs about how amazingly I turned everything around."

What more frequnetly (much more frequnetly) happens is usually some mix of:

* developers not really understanding why exactly the previous version failed,

* developers not really understanding what actually worked well in the previous version,

* developers completely underestimating actual amount of accumulated knowledge in the old system that they now have to replicate. Obviously, they only discover it along the way when it is suddenly too late to fix the design to take all of that stuff into account.

* developers not appreciating the fact they are in a much very different (worse) situation than original creators of the previous version. The creators of the previous version had time to build the system and then slowly evolve it. But the current team has typically a short time horizon to replicate ALL of it.

* as the resources are shifted from the maintenance of the old system to the development of the new, suddenly the clock starts ticking and the stakeholders are impatient to see the result. The pressure grows quickly and with it comes inevitable compromises and technical debt.

* at some point development team is told they have to start maintaining the old app. The resources devoted to the rewrite shrink, the work grinds to a halt. I have seen many more systems that have been in a state of perpetual migration than I have seen ones that have been successfully completed rewrite.

I think the authors do not understand how planetary resonances work and how precise (or imprecise) the orbits need to be for the resonance to hold.

Resonances are very common. We have lots of resonances in our Solar system in all different places between bodies.

For the resonance to be stable, two bodies do not need to have mathematically precise orbits in relation to each other. There is quite a wide margin for error. Once two planets are close enough to the resonance, the resonance may become stable due to feedback. What happens is planets will exchange energy back and forth on each orbit in a way, that preserves the resonance. A substantial input needs to be provided to break up the resonance.

What is actually interesting about this particular system is the long chain of resonances. But that is also nothing super special -- once you know how resonances form you can see how all of the planets, when they are close enough to the resonance, will transfer energy between themselves to snap into it and then continue on their resonant orbits.

There is absolutely no reason to suggest that a resonance like this must have come from unnatural origin. It would be like saying that because the period of our Moons rotation is so precisely the same as period of its orbit around Earth that it always faces Earth with one side, that somebody must have put the Moon on the orbit. That's obviously false, these resonances form easily and naturally.

That's exactly what is happening. But it is also not enough for the airplane to fly.

In a normally flying airplane, the wing compresses and pushes an amount of air under its wing. But there is actually even greater amount of air sucked down by the region of underpressure created above the wing and by the laminar flow directing it downward. Here, the drawing at the top of the page makes it clear: http://www.amasci.com/wing/airfoil.html

When you have a stall condition, what happens is that the air below the wing is still being compressed and directed downwards, but the air above the wing becomes turbulent and "unsticks" from the surface of the wing. Rather than being nicely directed downward, it just dissipates a lot of energy in turbulent motion that is not directed in any particular direction.

This turbulent air not only ceases to provide lift, it also prevents the air from below the wing to be directed downwards efficiently.

The main job of an airfoil isn't to create a pressure difference, it is to create conditions for the air to be laminar at as wide range of speeds and angles of attack as possible to make the plane nicely behaving and possible to takeoff and land. It is super critical for landing as you need to have higher the angle of attack the slower you fly and all planes essentially are driven as close to stall as possible during landing. Similar happens at high altitudes and high speeds, but for a bit different reason (read up on "coffin corner" if you are interested in that sort of thing).

Thank. You. That's exactly what is missing and that's exactly what I have mentioned in my... highly criticised comment. It just shows how pervasive the misconception is.

If you take a step back there is a simple way to think about this. In order for the object to stay up there, there needs to be equal and opposite force from some other body. What is that other body? It is the mass of air that is being directed in the opposite direction of the lift force acting on the plane.

I wish every presentation on how planes fly started with an actual flat plane. A wing that has a flat crossection. I think the shape of the airfoil of the wing is absolutely distracting and prevents people from understanding what is really happening.

Every person who ever stuck a flat object outside the window of a moving car knows that you do not need a fancy shape to have lift.

And so many people are stuck thinking that the shape of the airfoil is responsible for the plane to be able to fly, supposedly because the air needs to run a longer way around the foil above the wing than below the wing. And this somehow causes pressure difference due to Bernoulli law and this is what keeps the plane up. Which is almost total BS because planes can obviously fly inverted.

Now I admit I only skimmed the article, and although the animations are beautiful, I am missing what really is key to understanding of what is happening.

I am looking for a bigger, far away view of the wing and showing what happens to the air BEHIND the wing.

Because how the plane really works is as it flies forward, it diverts large masses of air downwards. It pushes off of air.

Part of the air is diverted by the lower portion of the wing, but the much larger portion of lift is generated by larger masses of air above and behind the wing. Those can be thought as being sucked down behind the wing (if you look at it from the point of view of a stationary air mass, not from the point of view of the wing).

And the main role of the airfoil is to keep that mass of air behind the wing stuck to the airfoil at wide range of angles and speeds as possible, because a flat sheet is very poor at doing this.

That's a very good point.

I would add, that sometimes being a newcomer is a benefit. Many times a particular industry is stuck in groupthink, having shared understanding on what is and what isn't possible. And it sometimes requires a person with a fresh perspective to be able to upend it. See example of Elon upending multiple industries by essentially doing exactly that.

Of course. And the way to go is to set up incentives so that everybody wants to report issues rather than hide them.

In a normal, healthy situation a company like Boeing should not feel threatened if some problems are exposed from time to time. That is assuming that everybody understand that uncovering these problems is part of the process and is necessary to improve safety and is exactly why and how we have good safety in the first place.

It only becomes a problem when that safety record becomes blemished too much.

I am pretty sure it actually has worked successfully for many decades up until some point, evidenced by consistently improving safety record.

> I'd be curious to know how many non-conformances they typically see during assembly of a plane (...)

Very likely that number is meaningless. I suspect this is the kind of environment that incentivises hiding non-conformances whenever possible.

For example, better quality control usually results in an increase of number of defects, at least temporarily. But that just because large portion of these defects were undetected before.

So... you are looking at a number that you have nothing to compare to that also depends on how closely the process is monitored and also depends a lot on the definition of what is non-conformance.

It is like trying to give an answer to "what is the length of Britain's coastline?" Everybody knows that you can get whatever answer you want depending on how long the ruler is.

No. As a business owner you will hire couple lawyers, give them a bunch of programs to automate searching through texts, answering questions and writing legalese based on human description of what is the text supposed to do. These three are from my experience great majority of the work. The 2 people you hire will now perform like 10 people without tools. Then you will use part of that saved money to reduce prices and if you are business savvy, you will use the rest to research the automation further.

Then another business that wants to compete with you will no longer have an option, they will have to do this or more to be able to stay in the business at all.

I think what you are missing is businesses doing what businesses have always been doing: finding a niche for themselves to make a good profit.

When you can hire less lawyers and get more work done and cheaper and at the same (or better) quality, you are going to upend the market for lawyering services.

And this does not require to replace lawyers. It is just enough to equip a lawyer with a set of tools to help them quickly do the typical tasks they are doing.

I work a lot with lawyers and a lot of what they are doing is going to be stupidly easily optimised with AI tools.

> Laywers hoard their contracts and it was very difficult in our journey to find lawyers who would be willing to write contracts we would turn into templates because they are essentially putting themselves and their professional community out of income streams in the future.

I notice same things in other professions, especially where it requires a huge upfront investment in education.

For example (at least where I live), there was a time about 20 years ago where architects also didn't want to produce designs that would be then sold to multiple people for cheap. The thinking was that this reduces market for architecture output. But of course it is easy to see that most people do not really need a unique design.

So the problem solved itself because the market does not really care and the moment somebody is able to compile a small library of usable designs and a usable business model, as an architect, you can either cooperate to salvage what you can or lose.

I believe the same comes for lawyers. Lawyers will live through some harsh time while their easiest and most lucrative work gets automated and the market for their services is going to shrink and whatever work is left for them will be of the more complex kind that the automation can't handle.

Not doable.

There exists nothing, even theoretically that you can put on the spaceship to get you that 1G continuous acceleration.

I don't remember exactly what is the maximum achievable delta V but if I remember well it is not a high portion of the speed of light, more like 60% of speed of light. And that assuming you have crazy things like carry a small black hole with you and use it to convert mass into energy at 40% efficiency.