Posts by John Robson

Re: get kids hooked on Microsoft 365 for life

Raspberry Pi, monitor, keyboard, mouse.

Single server running a network boot server.

So during the lesson everyone is using the class image, and out of class time (or in specific classes) an SD card can be used for a different persistent environment.

Heck, you could reasonable just have two different Pis... But it is slightly less portable (within the school) than this.

Re: I bet...

If you can get a remote desktop running, then does it matter?

Looks like a half decent thin client, potentially.

Re: So NASA will *never* make it to the Moon

Neither will I be.

Dragon to orbit, dock with Lunar starship.

Leave dragon in orbit of either the earth or the moon.

Starship to moon, land, take off, redock with dragon, return.

What's the big deal about throwing away perfectly good Shuttle main engines along with slightly stretched SRBs - reusable before it was feasible.

How much mess do you think they leave behind?

You're talking about genuinely tiny amounts of stuff to bury deep - as opposed to thousands of tons of crap just spewed everywhere, both the solid and the gaseous stuff.

Re: Windows updates

What's the value of your time?

And how much repair have you ever wanted to do to any of them?

I'm trying to remember the last time I had to repair a laptop, or a desktop.

I replaced the screen on a Surface Pro last year.

I upgraded the storage in my wife's laptop a year or so ago.

I added some memory and an SSD to the old mac mini about a decade ago.

I replaced the screen on a Toshiba laptop about twenty years ago.

Basically everything else I've ever done in the last twenty years has been to a server - different kettle of fish entirely.

I used to gut and fettle with computers constantly, but they have long since fallen down into the same category as any other tool. If I can make a tool that falls apart every year but can be put back together is that better or worse than one that doesn't fall apart but couldn't be put back together (because I welded that "weak" joint).

Re: I wonder?

But you have a level of battery storage that you need to cover for grid outages

You presumably need that level of energy storage to allow for a reasonable time to pass and to kick in the generators for longer term power delivery.

If you start using those batteries as time shift - you need to leave the capacity that was chosen for the above task available, so you need more batteries to deal with the time shifting.

Most datacentres won't have hours of battery standby, they'll have a few minutes, just enough to get the generators started (with the assumption that the power outage won't have been caused by a tsunami that floods the generators as well).

5-10kW/rack isn't unusual - so a one hour backup would need 5-10kwH of battery *per* rack - that's easily 15% of your rack (6u out of 42 is 14%) taken up for just one hour of storage:

https://www.greensunpv.com/48v-50ah-lifepo4-battery-2400wh-storage-lithium-battery-pack-51-2v-lithium-ion-battery_p144.html

Data centres are power hungry - and I've completely ignored the AC requirements (although these are now a much smaller portion of the overall DC power budget than they used to be).

Re: I wonder?

Small turbines are fairly useful - but not for a data centre.

Given a small baseload (e.g a home) you might only have a couple of hundred watts of base load - and a small turbine can really help there.

Re: I wonder?

Yeah, great - but now you need twice as much battery, because you need all that you had in the event of an actual power outage.

Re: Costs are rising everywhere

"The UK standards are pretty much identical to EU ones. If you meet the tougher one, you meet both."

Not necessarily, and you still need to prove to all the countries you export to that you meet the EU one.

Re: Get rid of the religious exemption.

"But all of Islam, Judaism, Hnduism, Jains, Sikhs, Vegan Society, their religious leaders considered the issue, carefully, and decided that these were exemptions worth making.

Does that help you with your thinking?"

It reinforces my thinking - because my thinking is that it's worth listening to their objections and talking to the various group leaders.

Re: Get rid of the religious exemption.

"Yup. Public health is about the greater good, not just shareholder profits. The idea being that with a dangerous, communicable disease, it's in the public interest to prevent it spreading. So Typhoid Mary could be quarantined against their will. "

There is a significant difference between forced quarantine and compelling someone to act against ethical/moral principles. I like cows, I particularly like how they taste, but there is no way I would look to force a vegan to wear leather shoes or eat a steak...

In this instance I am not aware of any religious objections to the available vaccines, but it's not unreasonable to look at whether an exemption is appropriate (in either direction) - particularly if there are further vaccines being looked at which might bypass those objections altogether.

i.e. I don't think it's a clear cut issue in terms of moral principles.

Re: Get rid of the religious exemption.

By your very logic there is a proportion who do, so for every individual who selfishly chooses not to get vaccinated there is another n% of a bed taken up... That might not even be a large number, but the number of idiots who can't work out that a vaccine is good for them is also large.

They also of course are more likely to pass covid on, because a) they're more likely to get an infection that takes and generates significant viral load and b) they're more likely to shun masks and distancing at every opportunity, whether legal or sensible.

Re: Get rid of the religious exemption.

So a vaccine is developed that's delivered on beef - should vegans and vegetarians be forced to partake?

There are occasions when an objection is valid - I am not aware of any which apply to *all* of the vaccines on offer for this particular disease (and even one vaccine which doesn't have an objection is sufficient to bypass the issue entirely).

Given that we need a high proportion of people to be vaccinated, not necessarily 100% it's probably sensible to look at how many people end up with medical and religious objections.

Re: Start Stop

I was taught that selecting neutral was done *after* you were at a standstill.

Your hand could then go straight to the handbrake.

Re: Start Stop

The handbrake is a simple device to hold the car still without blinding the motorist behind you with your very high intensity brake lights.

If you are stopped for any length of time (i.e. probably not a stop sign, but certainly for traffic lights) then use of the handbrake used to be strongly advised. But then driving used to be about making *safe* progress and looking out for other road users.

Now it seems to an all out arms race to blind everyone else on the road because they've just blinded you with their ridiculously overpowered and point source lights.

Re: Start Stop

Only if you leave it on for an extended period (like overnight). usually there isn't a separate set of pads that the handbrake uses, so it's no different from leaving your foot on the brake in terms of pad behaviour (just less risk in terms of foot cramp/day dreaming/blinding other road users)

Re: Start Stop

So leave the clutch depressed, then you don't need to pull back into gear.

I know I'm old but I was always taught never to coast like that, it removes a control interface you have with the car.

Re: Start Stop

So you're driving along in neutral with the clutch released - why?

Re: Start Stop

And some cars make it look like that.

My car for instance keeps the brake lights on, even though the handbrake is applied.

It applies the handbrake automatically, and releases it automatically, but it keeps the blooming brake lights on blinding anyone behind me... (I haven't checked what it does if I manually trigger the handbrake).

Re: China

Or they are just keeping the listing active whilst putting the price up to the point noone will buy

Re: Cheap cars

A Bicycle?

Or nothing...

Neither are suitable for everyone, but they aren't ridiculous options for many people.

Re: "[integrated combustible engine] "

Given the context I think it was pretty clearly a reference to the archaic power plant of yesteryear. </sarcasm(50%)>

Re: Start Stop

Ok, so it does it when you take your foot off the brake pedal then... not really substantially different.

Personally I tend to leave toilets with their lids closed, you know, prevention of accidental droppages etc.

Re: Start Stop

Yes - that would be annoying, but they don't do that, they won't stop if the battery isn't healthy enough to restart.

Re: Start Stop

What's annoying about it - Stop at lights, put yourself in neutral, release clutch, engine cuts.

Put clutch in to engage gear, engine starts so it's ready by the time you can drop the clutch to start moving.

Or does your car do something different to every vehicle I've been in with it?

Re: Hope

You don't need autonomous robots, just remote manipulators, and we're pretty good at those now.

Re: Hope

Depends on the launch requirements.

Both would take a dedicated launch - but what is the repair, how long is it likely to last.

Compare that with potential improvements from an HST2 (that's a better use of funds than HS2 anyway)...

Re: Hope

A Dragon has almost everything needed.

It has the orbital capability, and it has a docking adaptor - as well as a reasonably sized non pressurised volume.

If you accept Gemini levels of technology then you could simply dump the atmosphere and then refill fro bottles - though I imagine that the adaptor might be a bit on the tight squeeze side for an EVA suit.

Or we could use a remote manipulation system - they're a bit better now than they were thirty years ago...

The alternative (and yes it would be a few years in the development) is one I've mentioned before:

Use the "trunk" space to house a robotic arm - there's your coupling to hubble.

Additionally have an airlock - possibly inflatable - in there to attach to the docking hatch.

There are seven seats in a crew dragon, so you could have a couple of EVA suits and a reasonable crew.

The arm and airlock would obviously be single use...

Of course the other thing to consider is that the F9 standard fairing is 2.6m internal diameter, that's enough for the HST primary mirror already (2.4m), and we're clearly comfortable stacking mirrors and rearranging them in space (see JWST) (Atlas V, Delta IV, and Ariane V also fit the bill here by the way).

So it could be cheaper to not even wait for starship - just use a current commercial launch vehicle and a new set of flight hardware. Given the comparative accessibility of stuff in LEO, and the advances in remote manipulation in the last thirty years we could probably make it serviceable without astronauts in orbit.

How much would a new HST cost (original was $2B at launch)? Well, the launch cost would be nearly an order of magnitude lower than a shuttle (~$450m/launch for the shuttle, ~$50m for an F9)...

But the real costs were in the technologies developed for the HST, and those are much more "solved" problems now - To rebuild with modern compute, reaction wheels, sensors etc... would be substantially cheaper, and more estimate-able, since there are no novel technologies required (though it's still a bit more complicated than lego).

Then the question is... is it worth it to "just" replace an aging instrument... It might not be, the incremental cost between HST2 with a 2.4m mirror (i.e. a replacement) and a 10m mirror (i.e. an upgraded replacement) might be small enough that it's worth doing something new.

Or we could simply let it hang out, as a future museum piece - it's got to be one of the easiest objects to keep in a safe orbit, it's got a designed grappling point after all.