Posts by Alan Brown

"If you legitimately open the door by mechanically unlocking the door lock the alarm should not go off. "

It does on most european cars. Disabling the alarm is done with the remote and if you have to go in with a key the only way to silence the alarm is to put a valid (paired) key into the ignition.

Re: Been there, done that

"There was a joke back in the 70s & 80s that as all the particle physicists shared code, a significant number of the particles discovered were probably Fortran bugs."

They still do and they probably are - and they're still insisting on having Fortran 77 support.

> The "aircraft maintenance process" is overseen by the CAA, to stop people doing shortcuts.

And all the "paperwork" is on..... computers in BA's datacentre.

As were all the loadout calculations and a bunch of other safety critical functions.

Re: Latest config not saved

"Allright, my bet is that the power failure is caused by putting too much load on the circuits at one time. Either from a mass reboot or the cooling systems not behaving nicely, or being mismanaged."

If any of the above happen, then the power system is mismanaged.

If it can't survive a mass reboot then you beef it up or don't let such a thing ever happen

I can't fathom DCs which appear to only have one (or two) cooling systems. This falls under "not a good idea" for a number of reasons - and after some nasty experiences with dickheaded wiring on "centrally managed" cooling(*), I'm minded to insist on completely independent command and control systems for each one even if that puts the cost up a little.

(*) Hint: Guess what happens to your 5 "independent" cooling systems if the central panel goes "phut" ?

Re: Ethernet

"Networks are supposed to be redundant - that's the whole point of spanning trees and routing protocols."

Spanning tree operated over a domain more than 5 switches wide is a disaster waiting to happen (that's what it was designed for). It can be a disaster on domains even smaller than that if there's LACP involved (any LACP disturbances result in a complete spanning tree rebuild, so you don't want LACP to your servers unless the switches they're connected to don't use spanning tree to the rest of the network)

Thankfully there are better alternatives.

I deployed TRILL on our campus a couple of years ago. Whilst the switchmakers primarily push it as a datacentre protocol it was _DESIGNED_ for campus-wide/MAN applications and will work across WANs too. (Bypass Cisco and look around, there are a number of OEMs all selling using Broadcom's excellent Trident2+ descendants, with far better levels of support than Cisco sell)

Naked TRILL does leave a (small) SPOF - routers for inter-subnet work, but that was plugged a while back: https://tools.ietf.org/html/rfc7956 - The distributed L3 extension to TRILL takes care of that nicely and means one less complicating factor can be taken out of the loop (no need for VRRP or OSPF or other failover protocols within the network, just at the edges)

Re: LFTR time

"Wind and solar are fine, "

No they're not. Not by a long shot.

If you look at _actual_ installations and _actual_ outputs and scale them up to what's _actually_ possible (even discarding safety limits to allow for windmill blades going over a mile if they break off) and carpet the countryside in windmills and PV, you'll _just_ be able to match the existing electrical generation fleet.

And that's without even going into the issue that large windmills are eating gearboxes at a prodigious rate, such that pretty much the only way to make money off them - even with subsidies - is to be paid not to run them. Or the issue of the hydrofluric acid mess unfolding in China from manufacture of solar panels (putting the potable water of several tens of millions of people at risk)

Forget paving the Sahara. Firstly it's not ours and secondly the practical limit on electrical transmission systems before losses become excessive is about 1500 miles, unless someone's come up with some magic pixie dust that make ultra-low-loss Megavolt transmission lines practical (higher than that and they start arcing to ground) with the limit dropping to a few tens of miles for underwater links.

Chad, Morocco and others might be able to use it as a good power source but not Europe.

Now factor in that electricity accounts for 35-40% of carbon emission, with virtually all the rest being taken up in industrial processes (mainly heat), domestic heating (gas/oil) and transportation. Electrify those and you need to increase your generation capacity by a factor of _AT LEAST_ 6 to keep up, if not 8

Now factor in the developing world. You can't leave them out or their carbon emissions will simply rise to match what we reduce by, as they work to advance their economies.

To be serious about reducing carbon emissions and avoid an anoxic oceanic event, we need to have embarked on a crash nuclear building program a decade ago, but the problem with THAT is that there's nowhere near enough uranium available "off the shelf" to start the things and only enough reserves to run them for about 150-200 years at the scale required. Compare and contrast with _known_ thorium reserves at the scale required being about 200,000 years' worth and hundreds of thousands of tons available right now (it's a nuisance waste byproduct of rare earth mining and difficulty disposing of it is why most of the rare earth mines in the USA closed down)

Yes you need uranium or other fissiles to start a thorium reactor but think of it as a starter motor and once the thorium reactor is running you can syphon out enough fissiles to start a new one relatively easily.

The country which can build and distribute LFTR designs to the developing world over the next 2 decades is the one which will call the economic shots for the next 2-3 centuries.

Re: >"passive" safety systems that do not require human intervention

"I find mooted similarities in design with submarine reactors hardly reassuring in that context."

Ditto.

ALL the submarine reactors are based on the same basic Gen1 Weinberg principles - and they all use Uranium, which means you're spending an insane amount of energy and throwing away 90% of the fuel before it even sees the inside of a nuclear reactor - worse still, that fuel is a weapons proliferation risk.

More importantly, submarine reactors are _small_ and have virtually _infinite_ cooling capacity available (the sea's just outside the hull). If your design isn't capable of rejecting all its waste heat to air then sooner or later you're going to have a problem.

Re: The trouble with "failsafe"

"IIRC Windscale happened because someone thought it a good idea to have a reactor which basically worked like a coal fire, with a through air flow. Then the radioactive bits got hot and the carbon caught fire"

More or less. But remember that Windscale's _sole_ purpose was to produce plutonium to make nuclear weapons. The military (all militaries) has repeatedly played fast and loose with safety protocols when it's suited them to do so.

Bear _that_ in mind when you realise that the water moderated reactors we know and love are "modernised" and "safened" versions of an experimental nuclear reactor primarily designed as proof of concept - and whose inventor subsequently sat down and _built_ a new _intrinsically safe_ design with safety designed in at every stage of the process to ensure that operator abuse couldn't result in an accident of the kinds we've seen over the years and which didn't rely on bomb fuel to operate it.

Re: Russia

"The current new kid on the block is the sodium-cooled BN-800 which started up a couple of years ago."

Yeah, because liquid sodium is an intrinsically safe cooling material, even if the loop that happens to get exposed to air doesn't happen to be radioactive, and putting out a fire involving 30 tonnes of sodium that happened to find its way into the basement is easy. (Monju)

There needs to be a checklist of "SHALL NOT" for nuclear reactors and "be able to catch fire" high up on it.

The americans and russians never managed to stop their sodium rigs from catching fire and not to be outdone, the Japanese built Monju. The plant is now being dismantled.

I don't care that "modern technology means it will never leak", the fact that "if it does leak, it WILL burn, it's nearly impossible to put out, and it WILL burn a big hole in the loop causing the rest of the coolant to leak out, giving you an even bigger fire" means that even that "one in a million chance" is one too many.

Lead cooled sounds safe enough but the russians found out the hard way on one submarine that if you let it solidify you can't get to the fuel rods.

If you want to swing your power levels (load follow) then you can't use fuel rods. The Xenon needs to be able to be vented off because apart from the neutron poisoning aspect the sheer pressure of its presence inside the rods breaks the fuel pellets down to a fine powder. That's where MSRs win.

Alvin Weinberg looked at what commerce was doing with his lovely little submarine reactor (powered by uranium because that's what they had available at the time thanks to the weapons program), threw up his hands in horror at the safety issues and came up with an intrinsically safe design. His reward was to be fired and driven out of the industry. Would you run a car using cordite as the fuel?

Re: And what about solar?

"although worth noting that if you've got a monsoon season, there will be several months of very low direct sunshine, and that needs to be given some thought."

Contrary to popular opinion, monsoon isn't months (or even weeks) on end of overcast skies.

Re: Has there been anything beyond some marketing graphics yet?

" they came up with a different SMR concept, the PBMR, and they had a proof of concept plant built and working (IIRC). "

Pebblebeds are still being developed. The german ones had some safety issues which you'd kind of expect being an experimental setup and got shut down as a result.

Re: £875 per household per year!

"[2] mean you no longer get much rainfall (check how much civilisation in the Sahara!). "

This is one area of great concern for climate scientists. The effect on ~3 billion people of the asian Monsoon failing or significantly changing its pattern is something that should give pause for thought.

Re: Nice try, but...

"After flying once to NZ via the hell-hole that is LA transit, I have flown via Singapore to NZ since then."

I've been both ways several times. It's nicer via HK or BKK, but LAX was "best avoided" back in the 1980s let alone more recent times.

I haven't tried the Gulf route (yet) and the idea of a flight of that duration makes me shudder.

As for "Air NZ" - there are better airlines to fly to NZ with (and a lot worse ones too).

Re: "a pressurized hold is crew-accessible so as to deal with live cargo"

"Not all holds (many planes don't have a single hold, they have separated ones) are easily accessible by the crew"

MOST underfloor holds are inaccessible (without tearing up panels and carpets - some do have emergency access panels but the hint is in the word emergency). Even for the ones that are, contrary to TV representation, you'd find your way obstructed by LD3-type containers (actual type will vary by aircraft) - even if not full of cargo they'll stack empties in there to stop things moving around.

There might be a crew rest or other prep area below decks but these aren't holds and seldom offer access to the hold areas - and even if they did, the fact that it's stuff full of cargo containers isn't going to make access possible.

Re: Not a Chartered/Certifies Engineer or engineer but

"That means you can have great big gaping holes in the side of your aircraft and the plane will be able to fly and land without any problem."

That really depends where the holes are and how fast the aircraft is going.

The Lockerbie bomb only put a small hole in the side of the aircraft. Depressurisation made it a bit larger, but the protruding material at the edges caught a 600mph airstream and things unravelled pretty quickly from that point.

Re: Not a Chartered/Certifies Engineer or engineer but

"the pressurised cabin" ...."an unpressurised hold"

Whatever gave you the idea that holds are unpressurised?

Unheated maybe, but definitely not unpressurised on a jetliner, else the floor would buckle.

"It could become a a cancer hazard for frequent fliers."

I suggest you acquaint yourself with radiation doses from Xrays vs radiation doses from being at 30,000 feet (hint, the latter is far higher than the former and contains high energy protons in addition to simple ionising radiation)

"As it happens, we know that there has been a partially successful attack in Africa whereby a doctored laptop exploded, killing no-one but the attacker."

Said laptop was handed to the attacker AFTER he cleared security.

It's all about theatre, not reality.

Re: Natural barrier to runaway

"(#) I figured out that if built from 1940s-style valves/tubes with minimal spacing, a recent two-billion transistor Intel Core i7 CPU would occupy *six* 50m-high office blocks."

No it wouldn't. If you did that, it'd run for less than 5 minutes, then overheat and the minimal spacing means that nothing could ever be replaced. Allowing enough space for cooling and maintenance would increase that footprint by a factor of 20 or so. Then you need to factor in the power supplies.

1940s style computers made heavy use of 807 triodes. These had an operational life of 6-8 weeks under heavy load - or at least the ones I was constantly replacing in 1950s era SW transmitters during the 1980s did.

Re: Tata Consultancy.... surprised at incompetency.... I am not

"This is time for the british public to demand that BA "

The "british public" can't demand anything. BA is owned by a spanish private consortium.

So that's a lack of excellence in engineering OR customer service.

Re: Maintain your generators

"Also, people expect 3 year old fuel not to clog the filters."

Which is why you have circulation pumps, regular run tests, redundant filtration systems and duplicated fuel gauges.

Of course, if it's all put together by speed-e-qwik building contractors then you'd better be absolutely sure you covered every last nut bolt and washer in your contract and specified that any departures _they_ make from the plans are not allowed (else they will and then try to charge you for putting it right)

"You can't power the same stuff from 2 different grids at the same time."

Yes, you can: It's all in the secret sauce.

https://www.upssystems.co.uk/knowledge-base/understanding-standby-power/

And when it's really critical, you DON'T connect the DC directly to the external grid. That's what flywheel systems are for (you can't afford power glitches when testing spacecraft parts as one f'instance)

http://www.power-thru.com/ (our ones run about 300kW continuous load apiece and have gennies backing them up.)

For the UK, Caterpillar have some quite nice packaged systems ranging from 250kVA to 3500kVA - and they can be stacked if you need need more than that or to build up from a small size as your DC grows.

http://www.cat.com/en_GB/products/new/power-systems/electric-power-generation/continuous-power-module/1000028362.html

So, yes. This _is_ a solved problem - and it's been a solved problem for at least a couple of decades.

Re: Happenings ten years time ago

"I have some notoriously difficult to use air miles which I intend to at least try and use before I finish flying with that airline for good!"

They can generally be used elsewhere within the same alliance.

Re: Penny wise pound foolish

"So they're only telling 1/10th of the real story, enough to make everyone think they are not to blame, when in fact they probably are."

Which is probably why the utility companies are now all stepping forward to categorically deny any kind of power surge anywhere in the country.

Re: Back in the day...

"the office space contingency was to rent a spare location if our offices ever burnt down"

Oh, so you need that much space, that urgently? Sure, I can do that for a 2500% premium.

Re: Cynical Me

"Was there any review in terms of obtaining another genny and/or onsite sparkie during operational hours? No."

In other words, next time it happens the site manager won't bother.

It's amazing how much money there is to fix things AFTER the stable door has been smashed to smithereens.

Re: Is it because BA waived Tata

You say "the" data centre, like you expect it's normal to only have one of them.

Re: Really a power failure?

I've also run into cases of people unplugging stuff they shouldn't, to plug in stuff they shouldn't.(*)

And denied doing it - until confronted with CCTV evidence, then still tried to deny it.

(*) In one case, a toasted sandwich maker. That kind of shit belongs in the kitchen.

"beancounters that run businesses like Crapita (looking at you Serco, Egis, and Leidos) don't get really simple preparedness and mitigation concepts"

Then you ensure that the SLAs they sell you hold water and have penalty clauses.