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Comment Good fun (Score 2) 519

Isn't it fun, watching all the people who were out in the streets over the NSA's bulk domestic surveillance, suddenly reassuring us that there's all sorts of oversight over wiretaps?

Isn't it fun, watching all the people who cheered Snowden on, suddenly up in arms about "irregular" declassification of information by the president?

Submission + - Ask Slashdot: Distributed file sharing 1

DeathToBill writes: I'm a software engineer, and so also the guy who knows stuff about IT, in a company with five employees. All five are based in different cities on two continents. So far, we've used Dropbox for file sharing. The main drawbacks are the cost (£108 per year per user) for still-limited storage space, not-terribly-good collaborative editing, limited version history and very coarse permissions (top-level folder controls only). I'm looking into other solutions, but am finding it difficult to get a feel for how well different solutions actually work. We really like Google Docs' collaborative editing, but we'd like to still be able to use MS Office as users are familiar with it. As well as documents, spreadsheets and presentations, we also need to be able to share engineering outputs such as CAD drawings, schematics, PCB layouts and so on. Most of our work happens on Windows, but a couple of us (mostly me) switch back and forward to Ubuntu for some jobs, so a Linux client would be very useful (even if Office documents aren't editable there). We need some sort of permission control, preferably reasonably find-grained but easy enough for non-technical people to set permissions. At the moment we're getting by with a few GB, but that's becoming a struggle. Most of our users are usually connected, but offline access is occasionally important. We're currently using hosted services, but are happy to host our own if it makes it better or cheaper. What does Slashdot recommend? Is there something great out there that solves all of these?

Comment Economics (Score 1) 435

There are lots of other reasons others have pointed out, but I think it's also worth pointing out the economically bad timing of 3D TVs. Big-screen TVs got established in part because they were released during an economic boom when credit was cheap. Remember those people mortgaging their house to buy a TV?

3D TVs were released in the aftermath of an economic crash when credit was almost unobtainable. I think if manufacturers had a few more years of patience with the market, they might see a different result.

Comment Not news (Score 1) 504

This is not exactly news. On the one hand, it's true; solar is considerably cheaper than anything else in large swathes of the developing world and has been for a while now. It's only going to get more-so. However, that's only the case if you use it to offset grid usage; a complete off-the-grid solar system, with enough storage to see you through the night and the odd cloudy day, is still going to cost you more over its life than the equivalent grid supply. The costs are heading down, and it's not far off being worth doing in some places, but it's not there yet. There are a few cases where supply costs aren't the only consideration where solar-with-storage is already reliable for other reasons; we came across a mining outfit with a very large crusher and a very unreliable grid. Every time the grid cut out, their crusher stopped, and someone had spend a couple of hours climbing through it clearing out the half-crushed rubble before they could restart it. Concerns about the 'unreliability' of renewables are a very first-world thing, where the grid alternative has several nines of reliability; when there are more sevens than nines involved in the grid reliability, renewables suddenly look pretty reliable.

But. On the other hand, the cost numbers are a bit deceptive. The comparison, especially in the first world, is always for _new build_ capacity. So if you're looking to add 100MW capacity and the choice is between solar-with-storage and a new 100MW coal plant, solar might well out-perform coal in a few years. But if the choice is between 100MW of existing coal capacity and 100MW of new-build solar-with-storage, there's no competition and won't be, probably ever, for two reasosn: One, you've already spent the sunk costs of the coal plant and they're being amortized over the remaining life of the plant, so replacing it with solar means there is a sudden 'cost' to account for, which you've actually already spent but which you were planning to make back in the years to come but now can't. And two, because almost all the costs of renewables are in the construction phase (ie there is no fuel to buy), you need the money sooner than you do with fossil fuels, so you don't get to spend the money on something else. As a crude example, suppose you have two 100MW projects, each with a life of 20 years, one coal and one solar. The coal plant costs $50 million to build and you'll spend $50 million on fuel evenly over its 20 year life, while the solar plant costs $100 million to build with no operating costs. The overall cost is equal, but with the coal plant you have $50 million to invest in something else until you actually need the coal, while with the solar plant you've already spent your whole $100 million.

The exact difference depends on the (assumed) discount rate, and what number to use is a matter of considerable controversy. See eg. the Stern review, which assumed a very low discount rate, to make spending now look more competitive than spending in the future. To go back to the example, assuming a discount rate of 3%, the solar project has to cost around $88 million to be competitive with the coal project.

Comment Ineffective (Score 5, Informative) 351

Technical measures that prevent address spoofing are quickly becoming obsolete anyway; AFAICT, the recent attacks on Krebbs and Dyn, the two biggest DDoS attacks ever, didn't use spoofed source addresses. A spoofed address is only useful in an amplification attack, where you send a small request which provokes a much larger response; then if you don't spoof the source address, you get a huge firehose of responses coming at you and it's you that gets DDoSed, not the target.

In this case, the attackers didn't bother spoofing source addresses, because they didn't use an amplification attack; they just used a huge botnet all making ostensibly-valid requests and each device dealing with the response individually. It looks like the only way we have of preventing this sort of attack is to make the devices secure - easier said than done.

Comment Re:Offshore wind is very uncompetitive (Score 1) 222

The main costs in onshore wind are the grid connection and the cost of steel & fabrication of the tower sections. Between them, over 50% of the cost of the resulting energy. There is progress being made still in lighter, more flexible towers, but I'm not sure how much further there is to go; these days a 1% gain is a big win, while ten years ago a 10% gain was perfectly feasible (eg individual pitch control reduced tower loads by ~ 10-15%). The cost of the grid connection is largely out of the control of the project developer and no-one who is able to reduce it has any incentive to reduce it, so don't look for big savings there. Sure, there's another 40% or so of the costs that can be optimised, but that's spread over lots of small things, so eg halving the O&M costs will not make a big difference to the overall cost of energy. It's hard to see steel getting a lot cheaper than it is, so it seems likely that onshore wind is approaching its long-term cost.

Offshore is another matter. An offshore turbine is just an onshore turbine that's bolted to a support structure that's in the water (more or less) so the costs of the turbine itself are pretty similar to onshore. The main thing holding up the cost of offshore wind is being able to hire a suitable construction ship on a day when the whether is suitable. So yes, development of specialised construction ships that can operate in worse weather, and expansion of the fleet of such ships, is the big factor in bringing that cost down - though it's unlikely to ever match onshore wind. Floating turbines are also a concept that cuts these costs significantly - no need to drive piles into the ocean bed to anchor the support structure - though you do still need some seabed structure for the grid connection etc. I don't think anyone's quite ready to start building large fleets of these (though there are plenty of prototypes around).

Grid connection is a bugger, whether it's for a grid-scale wind farm or a residential solar panel. Way too much of the cost of these systems is just getting the thing connected to the grid. Feed-in-tariffs don't help here, as they make the metering more complicated (you have to measure imported and exported power separately, instead of just measuring net power imports). Someone ought to do something about that. Cheaper inverters and simpler meters FTW.

Comment Some basic flaws here (Score 5, Informative) 298

Off the top of my head:

1. "Every year we hear about people dying in plane crashes. This does not have to continue..." But air travel is already the safest mode of travel. Hear all those people screaming for new technology to make road travel safe? No? Well, they're the same ones that will take this up.

2. "Passengers might board a capsule at a local bus station and wake up in another city on the other side of the country, or planet, after a road, air and rail journey during which they didn't leave their seat." They don't seem to realise the blindingly obvious point that this is making air travel *worse*. Air travel already involves sitting in a seat for too long. Why would I opt for a mode of travel that exchanges a few minutes of having to be polite to people in the aisles for one that involves several hours more in the same damn seat?

3. If you want to see just how off-their-faces unrealistic this is, look no further than this sentence: "Clip-Air's researchers, who are also looking into the possibility of using biofuels or liquid hydrogen as alternative fuels, have already initiated some contacts with the aerospace industry." Oh, great! You're launching publicity for a total redesign of the entire global air freight and passenger industry and you've *already* initiated some contacts with the aerospace industry??? Really??? What made you do that so soon??? And looking into hydrogen as a fuel source for this is basically admitting, "It's so far off the page that we might as well throw in any futuristic-sounding crap we can." If you're doing this seriously, get one thing right at a time. Don't complicate it by also trying to introduce a fuel that no-one else has managed to make work yet.

People who consider themselves "aviation visionaries" (yes, an actual term used in the article) always, always get excited about this kind of thing for no good reason. They *think* people want revolutionary concepts that change how they board planes and let them work out then drink themselves silly in a trendy bar while they're in flight. What people *actually* want are revolutionary new concepts that cut the cost of air travel.

Comment You pay WHAT for mobile data??? (Score 3, Insightful) 145

Bloody hell. Here in the newly-independent UK[1], £11 per month gets me 1GB of data, among other things. Another £3 per month turns that into unlimited data. ANOTHER £2 per month turns that into unlimited data with 4GB of data usable by a device tethered to the phone. That's right, £16 per month for unlimited data on the phone and 4GB for tethered devices. "Heightened competitive environment"? Could still use some work, I think. [1] Yes, yes, I know.

Comment Difficulties (Score 1) 324

Two problems I see with this: 1. Safety. If the grid goes away, this thing will have no reaction torque to apply, and it ain't gunna stop in a hurry. 2. Scale. A quick look at Wikipedia suggests that the heaviest goods trains in use anywhere are about 40,000 t. Suppose you have a mountain where you can raise that 1,000m. The energy involved is roughly 40,000 * 1,000 * 10 * 1,000 = 4e+11 J. That's 4e+11 / 3.6e+9 = 111 MWHr. It's not small cheese, but it's also not national grid scale. As I sit at my desk, demand on the UK national grid is ~31GW. It will last 4e+11 / 3.1e+10 = 12.9 seconds supplying the whole country. That 40,000t train is about four miles long, BTW, so there's a limit to how many of them you can put on the same bit of track. As I say, it's not small cheese, but at the same time, in our renewable-powered future, being able to smooth out a few hours of low wind is going to require a lot of trains and a lot of quite large mountains to drive them up.

Comment Re:Cliches (Score 1) 324

I know you meant this to be funny, but you're probably right. For this to work, of course, it has to use regenerative braking to return energy to the grid. So what happens in a grid-fault scenario, when the regenerative braking can't apply any torque to stop the train?

Comment Re:It's wildly unlikely we should exist (Score 2, Interesting) 267

One flaw? Every single sentence in that quote is either false or unknown. Let's review:
  • It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. The universe is not infinite. It may be unbounded (ie have no edges), but that is different.
  • However, not every one of them is inhabited. This one might be true. It is, as far as we know. It might be argued we don't know very much, though. Inhabited with what is not specified.
  • Therefore, there must be a finite number of inhabited worlds. False, as you point out - supposing that the premises are true, the number of inhabited worlds may or may not be infinite.

  • Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero.The first half is true-ish. Certainly the limit as x->infinity of y/x, for finite y, is zero. What relevance this has to the remainder of the sentence is not clear. If the number of inhabited worlds is finite, then so is their population and each populated world will have a finite, non-zero average population. If the number of inhabited worlds is infinite, then so is the total population.
  • From this it follows that the population of the whole Universe is also zero False, since its premises are false. Even if the premises were true, infinity times an infinitesimal number is not zero.
  • and that any people you may meet from time to time are merely the products of a deranged imagination. This depends rather on your personal situation.

Comment Re:AC is by its very nature inefficient (Score 3, Insightful) 245

If you don't understand why this isn't going to happen, you need to be kept away from grid design.

Replacing the AC network with a DC network would mean either replacing or substantially modifying the entire fleet of existing generation plant, all distribution and conversion equipment, all industrial equipment powered by electricity and most appliances. You might well be right that you can achieve better efficiency in a new network with DC than with AC; when you have to replace the entire electricity system, from spinning turbine to phone charger, it just ain't gunna happen.

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