Germany is turning on its monster stellarator • Hacker News Board

Re: Germany is turning on its monster stellarator

#121

Post by HerpDerpLerp » Mon, Nov 02, 2015, 4:09 PM UTC

annnnd wrote: post #104

fsloth wrote: post #96

Earlier quoted context omitted.

Not all functions are refactorable. A 'purely hypothetical' scenario: a numeric routine of several klocs on length, that takes in 20 parameters with 1-3 letter obscure variable names, was written 30 years ago in fortran, was f2c:d 20 years ago into c and has been doing it's 'stuff' correctly ever since somewhere in the bottom of mission critical code in a codebase of millions of lines. Commercial codebase. Only a han…

The scenario you describe is a disaster waiting to happen. Refactor it, preferably yesterday - but make a "shadow deploy". For each set of input / output parameters run both functions and compare them. If they differ, use the old one and go back to figuring out where it went wrong. After some time you can be quite sure that the new clean function works as it should - then you just switch.

I am not sure the above idea is mentioned by Michael Feathers in his amaze book "Working Effectively with Legacy Code" but it is a great idea, and combined with the things that Michael does cover will do you a lot of good!

http://www.amazon.co.uk/Working-Effectively-Legacy-Michael-F...

Re: Germany is turning on its monster stellarator

#122

Post by kuschku » Mon, Nov 02, 2015, 4:10 PM UTC

drjesusphd wrote: post #117

kuschku wrote: post #75

Earlier quoted context omitted.

Tokamaks need, to contain the plasma, a continuously changing magnetic field. To create a continuously changing magnetic field, you need to continuously increase or decrease the current. The issue is that you can not turn up the current more than a maximum level, and you have to keep the direction the same (so you can’t switch between turning off and on). Stellerators instead solve this with complex geometry and the…

> Tokamaks need, to contain the plasma, a continuously changing magnetic field Do you have a citation for this claim?

I could source one from German Wikipedia, but english wikipedia does not seem to have that information.

You might be able to find some sources when you search for the reasons of Tokamaks pulsed usage.

Re: Germany is turning on its monster stellarator

#123

Post by prodmerc » Mon, Nov 02, 2015, 4:14 PM UTC

scrumper wrote: post #111

prodmerc wrote: post #26

"Designed in Hell" - really? Goddamn, I hate modern media outlets...

Worth pointing out that this phrase was the title of a linked 3rd party YouTube video, not from Business Insider Malaysia who did a reasonably decent job on the article.

Yeah, nothing against the article, actually, but the video is from Science Mag - you'd think they'd be more professional...

Re: Germany is turning on its monster stellarator

#124

Post by madaxe_again » Mon, Nov 02, 2015, 4:16 PM UTC

jessriedel wrote: post #93

justifier wrote: post #87

Earlier quoted context omitted.

the first video claims a magnetic field strength of 2.5 Tesla(o) roughly that of an MRI(i) can anyone speak to sort of considerations that lead to this value? 2.5T seems insignificant considering the events it will be confining how sensitive is the field to magnetic interactions outside of the device? (o) https://youtu.be/lyqt6u5_sHA?t=301 (i) https://en.wikipedia.org/wiki/Tesla_(unit)#Examples

Steady magnets can't get much stronger than that. The very strongest steady magnets, purpose built, are in the 40-70 tesla range. I believe the limit is set by the break down of normal matter. Higher field strengths can be achieved, but only for fractions of a second and are general destructive.

Imploding coils. This stuff gets me every time I see it - chills down the spine. You can induce a field in the MEGAtesla range for an infintesimal amount of time. Take a copper (or superconductor, if you're feeling ballsy) coil, run a huge current through it from your enormous capacitor bank, set off a wad of high explosive surrounding the apparatus - the near-instantaneous collapse of the conductor causes the field within to become absolutely enormous - and equally importantly the Ts-1 - i.e. the rate of change of the field - again, you can induce enormous currents outside of the apparatus through induction.

This technique is mostly used in solid state and, surprise surprise, fusion experiments. Oh, and you can make an EM bomb if you make a big enough one, and wipe out a city's electronic infrastructure in a microsecond. https://en.wikipedia.org/wiki/Explosively_pumped_flux_compre...

Re: Germany is turning on its monster stellarator

#125

Post by balabaster » Mon, Nov 02, 2015, 4:29 PM UTC

TeMPOraL wrote: post #97

balabaster wrote: post #41

Earlier quoted context omitted.

Mostly it's inspiring because most people sit back and say "It can't be done, it's impossible" or "wow, they must have had a shit ton of luck to get this out of the door" instead of looking for solutions or ways to circumvent or exploit the million little problems along the way that seek to obstruct the endgame. Kudos to these guys for sticking at it long enough and persevering to achieve their vision.

I guess different people see different things in such projects. What I see: - *massive* success of coordination and cooperation - illustration of potential humanity has - that careful and methodical approach can make even such monsters of recursive complexity work Luck does not enter the picture. Will and determination do though.

You'd be surprised how often will and determination is more of a factor of success than luck.

[Your level of surprise may vary]

Re: Germany is turning on its monster stellarator

#126

Post by nerdy » Mon, Nov 02, 2015, 4:55 PM UTC

balabaster wrote: post #83

nerdy wrote: post #77

Earlier quoted context omitted.

My inspiration from massive science projects is more like: "With that in mind, debugging this 1500-line function is nothing!"

Dude... refactor that shit. There is no place in today's development world that a 1500 line function is okay :P

It's a legacy system developed by someone who is lucky he lives 4300 miles away!

I've been working at the system to free it from that subsystem with an eventual replacement. There are all kinds of single-letter variables and Russian words, refactoring wouldn't be economical or sane.

Re: Germany is turning on its monster stellarator

#127

Post by DennisP » Mon, Nov 02, 2015, 5:19 PM UTC

campers wrote: post #14

hahainternet wrote: post #5

Earlier quoted context omitted.

I was chatting about this with a friend and there are something like 5 different in production technologies which produce or cause nuclear fusion. Only three I think are aimed at sustainable power generation, but it's still pretty cool.

I hadn't heard of this one before, always interested in fusion news. 3 others I know about are http://www.generalfusion.com/ http://lawrencevilleplasmaphysics.com/ (Focus fusion) http://www.lockheedmartin.com/us/products/compact-fusion.htm...

Tri-Alpha is the biggest private effort...about $200 million invested, 30 Ph.Ds, 150 employees. They recently announced they'd achieved stable plasma, the only major milestone left is scaling up the temperature. They think the plasma will get more stable at higher temperatures. Like focus fusion, they're attempting boron fusion.

Helion is similar to Tri-Alpha but with a pulsed design instead of steady state. They have funding from YCombinator. Instead of boron they're shooting for a hybrid D-D/D-He3 fuel cycle (the D-D reaction produces He3). They say only 6% of the energy released would be as neutron radiation.

Sandia's MagLIF project is interesting. According to their computer simulations they can get 100x to 1000x energy gain by preheating a fuel capsule and crushing it in an upgraded Z-Machine. Things are looking good so far.

UW has the Dynomak project, which is fairly similar to tokamak but a lot smaller and cheaper. They need $10 million to test the concept.

Re: Germany is turning on its monster stellarator

#128

Post by riffraff » Mon, Nov 02, 2015, 6:01 PM UTC

sp332 wrote: post #91

riffraff wrote: post #81

Earlier quoted context omitted.

and yet the "I was only following orders" line of defense should not be very popular anymore, especially in a german context.

It's not a defense. It encourages lower-level employees to come forward with incriminating information about higher-ups, even if if would also incriminate themselves. It's the best way to get them to roll over on their bosses.

The same logic applies to management, wouldn't it? So a middle manager should not be punished, if he incriminates a higher level manager. Until what level is it ok to get a free pass incriminating your boss?

People should be encouraged to come forward _before_ they do something illegal.

If you reward lower level employees for doing it after the fact, the rational thing for them to do is to continue acting illegally, as if the thing blows up they will be bailed out, and if they don't they might still suffer the consequences of it (i.e. get in bad relations with their boss).

I am not saying there is the same level of responsibility, but there should be _some_.

Re: Germany is turning on its monster stellarator

#129

Post by vidarh » Mon, Nov 02, 2015, 8:37 PM UTC

kuschku wrote: post #105

vidarh wrote: post #80

Earlier quoted context omitted.

On the other hand it teaches those on the ground that obeying illegal orders is perfectly fine, because, hey, you won't get punished.

It is also the only way you get people ever providing evidence against their boss, as otherwise they'd risk incriminating themselves.

You can support that goal by offering immunity to whistleblowers.

Re: Germany is turning on its monster stellarator

#130

Post by kuschku » Mon, Nov 02, 2015, 9:24 PM UTC

vidarh wrote: post #129

kuschku wrote: post #105

Earlier quoted context omitted.

It is also the only way you get people ever providing evidence against their boss, as otherwise they'd risk incriminating themselves.

You can support that goal by offering immunity to whistleblowers.

Well, offering immunity to everyone who just followed orders is an important part of doing so. And it makes in this case everything a lot easier.