Follow Slashdot blog updates by subscribing to our blog RSS feed


Forgot your password?

Comment Re:What makes a programming language 'Good'? (Score 1) 92

Exactly! For those who want to dig deeper, the keyword is "typeful programming". I.e. where one uses a sophisticated type system with type checking, to encode and reason about many of the properties/requirements of ones programme.

For those programmers who haven't been exposed to it, explaining what it is, is a little like trying to explain the ocean to someone who grew up in the desert. It's a mistake to dismiss it with a: "Sounds like just a lot of water to me". Instead, I encourage getting ones feet wet. Exposure to functional programming techniques will make one a better programmer, no matter what technology one uses.

Comment Re:Most likely they'll encounter interstellar debr (Score 1) 122

This is why it's too expensive for ISPs to roll out fiber in the USA compared to Japan or Korea.

Nope. Like matter in space, you USians are all clumped together. You don't need to roll out fibre to the middle of nowhere, since no-one lives there.

You have three times as many people in California as we do here in Sweden (we're roughly the size and shape of CA). And yet we have much better and cheaper fibre than you do. It's got nothing to do with average population density as you have us solidly beat on that measure (Sweden: 24/sq km, CA: 97/sq km...)

Comment Re: Show me (Score 1) 152

Yes, I described that effect in an earlier post. It's the main (i.e. what you're aiming for) effect behind the effectiveness of torpedoes or mines.

But it takes a much larger bubble for that effect to dominate over simple concussive effects. We're talking warheads with hundreds of kilos of explosive here, not 2 kg... For a small pop like a contact mine, it does have to be in contact.

Also, note the buoyancy of the bubble mentioned in the wikipedia article. You need the bubble to form under the target, not at its side for any real effect, which is were we're attaching these limpets. (Just look at the water spouts from missing artillery shells, they go up, not sideways :-)). C.f. Barnes Wallis bouncing bomb. Even though it was substantial in size, it had to be made to hug the dam wall, for it to have maximum effectiveness. You couldn't just drop it in the middle of the dam and be done with it.

Comment Re:Show me (Score 1) 152

It's not so much the explosives that do the damage, but the water that flows in after that can take down a ship.

Well, of course ultimately what sinks a ship is water inside the hull, aka not being able to keep it on the outside. But the story is more complicated than that, the main point being that ships have pumps and watertight compartments, so just making a hole in the ships hull isn't always successful. You have to make a large hole, preferably into a large compartment and one that's difficult to get at from the inside (to frustrate efforts to plug it). Or many smaller holes in different places, hence the practice of attaching many limpets when time and resources permitted.

Modern weapons actually use the physics of water to make that hole. A modern torpedo will detonate well below the keel of the ship to make a large cavity from the blast bubble. This makes the ship "sag" into the hole, breaking its back if your lucky, and when water rushes in to fill the cavity a spout will form that can cut the ship in two. All without trying to hole the ship as such, like older weapons did. (This takes a lot more explosive though...)

Comment Re:Show me (Score 1) 152

Yes, 2kg was the weight of explosives in the classic British limpet mine. So well below the waterline it could and did sink a ship, but in order to reliably take town a such a large vessel, and especially a man of war at that, with more and better damage control, you'd probably need a lot more than one limpet.

When the Norwegians sank the SS Donau (a 10000 ton ship, much smaller than Queen Elizabeth) they attached ten mines, and even that gave the captain the time to beach the ship.

So 2kg of explosives applied on the outside of the ship can do some damage in the ideal case, but probably not catastrophic when the ship is manned and ready.

Comment Re:You got fired... (Score 2) 1256

Yes, but in Sweden during the same time we've had a sea change in medicin (both human and veterinary), law, and journalism.

All these areas are now gender imbalanced, but with women being in the majority (sometimes very clear majority; 57% of judges overall, more in younger cohort, about 2/3 of younger doctors. etc. etc.). Even if the imbalance isn't as great as it was in favour of men in the eighties we're getting there.

But while these changed drastically, engineering OTOH is about the same as it always was. No great change.

So, the only conclusion then is that we have a society that "forced" women to take down the male bastions of medicin, media and law, but left engineering untouched? It's OK to decided about life and death in law and medicin, but for the love of God don't design a bridge? (Well, that's a poor example as there were always more women in civil engineering than comp. sci.) It doesn't sound like a realistic argument.

Look, we have our fair share of screwed up policies and notions, but we're not that inconsistent... It's pretty clear to me that the answer has to lie elsewhere.

Comment Re:I hope he pounds the shit out of google (Score 1) 711

Perhaps. This woman argues that the differences are self-exaggerating, that fields which fewer women are interested in pursuing tend to be male-dominated, which makes them even less attractive to women, which makes them more male-dominated, in a cycle which leads ultimately to a situation where only the women most devoted to the field stay in it.

But that's taking the argument one step too far already. If the question was why the situation at Google is 80-20 one needs only to look at the graduation statistics from US Comp Sci PhD programmes (if Google hasn't changed their hiring practices recently), where the figures are indeed in that range (and that's counting mostly foreign women, without them I seem to remember that the figure would be closer to 90-10).

Now you're already addressing the question of why women have opted out much earlier in the chain, and while that is interesting, it's not really something that Google can fix with their hiring practices, they can only hire from the candidate pool that is there after all. It takes something else. In another part of society (of which admittedly Google is a part, so they can do something, of course).

Now, I know from first hand experience in the academic teaching field how unpopular it is to (as I've had to do) point out that our targets and goals of increasing comp. sci. female undergraduate admissions were completely unrealistic as we would have to attract (in that case) all qualified girls from high school, not a single one would be left for medicin, law, etc. which we know already attracts a majority of the qualified female students. But like the aspie idiot I am I feel it still needs to be pointed out. (And I have tenure, so I'm harder to fire... :-))

Our answers in both acceptance and hiring to the "WHY DON'T YOU X MORE WOMEN" (where X is hire/accept) is and continues to be, "because they aren't there and they don't apply". We can't fix that at the end of the pipeline. (And I've been exposed to that in both industry and academia for more than twenty years, no come to think of it, it's closer to thirty...)

And being in Scandinavia I'm not sure I buy the "there are too many men there" argument. Thirty years ago that was very much true of medicin, veterinary medicine, and law to mention just a few highly sought after careers, difficult to get into and more importantly almost 100% male. And today Swedish universities have been e.g. fined for instituting "affirmative action" programmes for boys so that the veterinary programme (or was it law?) wouldn't be completely female. (But that's against the law, so no boys in that field...)

For example, in 1992 (Sweden), medical doctors 55-62 were 93% male 7% female. In 2010 in the youngest cohort it's the other way around, with 39% men and 69% women. If the "(old) men scare away women" hypothesis would be true, then this change of affairs is a very clear (data) point against. At the very least it didn't work on doctors.

Or lawyers, 57% of all judges in Sweden are women now. 55% of all judges in criminal matters are women, and that's set to change even more, as their dominance in the younger cohorts are ever more marked. If not even the grumpy old judges managed to scare the dainty young women away, well, that's another pretty hard blow against that hypothesis. (That doctors are wishy washy and can't put their collective foot down is after all somewhat believable, but scary and scarred judges, well they were kind of our last hope! :-))

But of course in comp. sci. the figures are pretty much identical to what they were in the eighties. There are a few more now, but we haven't nearly have the sea change that we've had in medicin (both veterinary and human) and law.

Comment Re: End of subsidies (Score 1) 474

Tell me, when was the last time that you welded a large-diameter zirconium-alloy pipe and X-rayed it for defects, with any possible sign of imperfection meaning having to cut it off and start from scratch? How many people in the world do you think have that skillset? Because that's what's involved in nuclear power plant construction - it is extremely exacting.

That said, the reason that we don't have the necessary skill set readily available today is because NIMBY-ism and regulatory hoops (esp. laws regarding public purchasing - cheapest bidder wins) means that nuclear is a more or less dead industry. When everything you ever build is a once-in-a-lifetime one-off, of course you're not going to reap any benefits from economy of scale, a mature subcontractor market, industry tradition and knowledge etc. etc.

So, the politics mentioned above did manage to kill nuclear, but indirectly, by making it such an uncertain (huge political risk) and unattractive field that the economy to support is isn't there. It's not inherent in the technology itself, we managed to do this (including welding) well enough in the sixties and seventies; as a species we're better at it now...

Comment Re: Change the cipher... (Score 1) 50

I know exactly what this is... what I am suggesting could be quite easily layered over top of that by software running on the end point devices...

That's the problem. They're satellite phones, so there's no "easily" in changing the endpoint software. Your solution amounts to "change the cipher to a more secure one". Well, yes, indeed, that's what we need to do.

That you can always run your own crypto on top of the one provided by the carrier is kind of trivially always true, but most often not a realistic option.

Comment Re:Please illuminate me (Score 1) 164

Large/mid-scale hog fuel/chip boilers can be extremely efficient and clean.

That said, smaller installations, like in a house, aren't that efficient, even though they've become much more advanced (with fans, lambda sensors and whatnot) in the last couple of decades.

Instead, what is typically meant is CO2. A wood fired boiler will of course have much lower net CO2 emissions as they don't burn fossil fuel.

When it comes to particulate matter and a few other nasties, smaller wood installations are actually pretty bad. Esp. in our cities.

Comment Re:Pffft (Score 2) 164

Welfare in Norway is good enough that this isn't an issue.

It's not even a question of that, but of cost. Heating oil in Norway is considerably more expensive than electricity, and having travelled and worked in Norway I can't remember when I saw something other than electricity (radiator or under floor heating), though of course wood (often in the form of pellets) is also popular.

Electricity is dirt cheap in Norway, so people even typically don't have a heat pump (like we do in Sweden), but just heat directly with electricity. As an example, for a 600 sq foot apartment with three outside walls, in the "cold" part of the country (two hours north of Oslo) I paid about $50 USD per month for electricity. That includes heating. In winter. Rent was $750 USD/month, so heating/electricity didn't add much.

In the Nordic countries we haven't installed oil fired boilers since before the energy crisis in the seventies. It's only houses with a very old heating system that burns oil these days. A system that should be well past its replacement days.

So that's why the Norwegians make this rule now. Usage is already virtually nil, so banning them won't have any real effect. Furthermore a typical oil fired boiler can be converted to burn wood pellets for, say $1000 USD or so, so even though a cheap conversion like that has it's disadvantages, it's not exactly a deal breaker if you own a house.

Comment Re:Solar Panel Not Equal to Spent Fuel (Score 2) 376

Well, while I agree there are problems with the article, in fairness 1kg of "spent" nuclear fuel won't magically develop wings and spread it self out to make a city the size of New York uninhabitable either. (And spent fuel isn't that dangerous to begin with. )

If you leave it alone, it will pretty much leave you alone as well. And a 1kg cube of spent fuel just sitting there won't be that dangerous. We store them in pools in our plants for the shortest lived, most active daughters to decay before sending them on after all.

That's not to say that just leaving it laying about is a good disposal strategy for spent nuclear fuel, of course. Far from it. And, equally obvious, neither does 300kg of solar panels present nearly as much of a hazard as nuclear fuel when dealing with the aftermath.

Comment Re:Why was CFC gasses so widely used in refrigerat (Score 1) 193

And it's not because the engineers were careless, stupid or did not care.

Oh, Thomas Midgley was both careless, stupid and did not care. It's not too long a shot to call his work in lead additives to petrol down right evil (check the link).

Now, whether he knew CFCs were bad, is somewhat moot given that it's not difficult to imagine that he would have gone ahead anyway. Like he did with tetra ethyl lead before.

Slashdot Top Deals

"Hey Ivan, check your six." -- Sidewinder missile jacket patch, showing a Sidewinder driving up the tail of a Russian Su-27