Please create an account to participate in the Slashdot moderation system


Forgot your password?

Comment Re: Simpleish (Score 1) 225

A lot of iron and steel foundries in the UK had a particular model of spectrometer built in the 1960s for carrying out analyses of metal samples. This spectrometer had an option of a hard-wired electric typewriter (not an IBM Selectric, a Remington or similar) that would print out the results of an analysis in a simple table. This was before Centronics printers were readily available. Back in the early 80s I worked with a consulting metallurgist to add a box to tap into the signals from the analyser to the typewriter and present them to a parallel-port interface so they could be read by a desktop computer. From memory the drive signals were at 24V with some weird pulse combinations for shifts, code pages etc. that we decoded by trial and error -- the company making the analysers wouldn't hand out the information and we couldn't mess with their internals since they were covered by long-term maintenance agreements (decades and more, these were very expensive bits of kit). We got the interface to work and the foundries were very happy to pay us to get the information out in digital for eventually supporting ISO9000 chain-of-custody certification which was necessary given that some of the places that used these analysers were making single large castings for paper-making machinery worth a million bucks a pop.

Comment Re:Radios? (Score 2) 229

How in the name of all stupid plot devices does each and every space suit, vehicle, structure and other large chunk of habitat equipment not have its own, independent up-link to the multiple Earth-Mars radio relays we already have in orbit around that planet?

Worked example -- the Apollo moonsuits had a short-range VHF link back to the Lunar Lander. From there the radio comms was via an S-band microwave link back to Earth. There was no direct link from the suits to the Command Module in orbit, even when it was above the horizon for the astronauts on the Lunar surface.

Comment Re:Charge takes 15 sec for 30 min (Score 1) 279

The digitising system used in the Surface Pro 1 and 2 was a Wacom-based design, it's now an nTrig in the Surface Pro 3. Both of them have pens that are powered by near-field from the digitising surface so they don't need separate power or charging at all. Since Apple are relying on their passive capacitive digitiser to work with the Pencil they can't power it that way.

Wacom provide a range of specialist stylii for artists such as an airbrush model, I'm not sure if nTrig do.

Comment Re:Stylus (Score 2) 279

The iPad Pro does have a separate digitizer.

This is from the Apple website page describing the Apple Pencil:

iPad Pro knows whether youâ(TM)re using your finger or Apple Pencil. When iPad Pro senses Apple Pencil, the subsystem scans its signal at an astounding 240 times per second, giving it twice the data points it normally collects with your finger. This data, combined with Appleâ'designed software, means that thereâ(TM)s only milliseconds between the image you have in your mind and the one you see on the display.

That doesn't sound like a separate stylus digitiser layer, it's more like the regular capacitive touch layer goes into turbo mode when the Pencil tip gets close to the screen.

We'll find out definitively when the first teardowns occur I suppose.

Comment Stylus (Score 1) 279

From what I've seen and read the iPad Pro stylus uses the classic capacitive touch sensor of the sort used on all the iPads, maybe with a higher-definition capability. That that means the user can't rest their hand on the screen while drawing. All the videos I've seen of users demoing the iPad stylus show them being very careful not to let their hand get anywhere near the screen, holding the stylus in a rather unnatural fashion.

The Surface Pro has a separate digitising screen for the stylus as well as the regular capacitive touch screen and it's possible to rest a hand on the Surface Pro's screen while writing and drawing as it can ignore the capacitive touch signal.

Comment Re:Moon orbit - why? (Score 3, Insightful) 93

The Sun isn't visible on any given point on the Lunar surface for two weeks every month and it gets cold at "night". An RTG-powered lander and rover can stay operational in such circumstances and the excess heat from the RTG can stop the electronics, motors, batteries etc. from freezing up and failing. The solar-only solution would require lots and lots of PV panels plus enough battery storage to, at the minimum, warm the lander/rover and prevent damage to the instruments and systems. That's a lot of extra mass to carry compared to a small RTG that can provide power and heat.

Comment Re:Water as rocket fuel (Score 1) 131

LH2/LOX engine technology is very well-developed and modern versions like the Vulcain 2, the RS-25 and RS-68/RS-68A produce close to the maximum possible Isp given the reaction chemistry involved absent a slight loss of efficiency due to the need to throttle up and down. The bad news is the amount of mass they throw out the back to provide thrust is low because hydrogen is a very light gas. Most LH2 engines run oxygen-rich to improve their total thrust by increasing the mass of the exhaust.

LH2-fuelled engines don't perform at their best in thick atmosphere as the large volume of exhaust gas is fighting the back pressure. LH2/LOX rockets really do well in vacuum where there's no back-pressure on the exhaust -- the Delta 4's RS-68 engine has an Isp of 365 seconds as sea-level (100kPa) but that increases to 410 seconds in vacuum.

The low density of LH2 also means the pumps, plumbing, injectors and most critically the tankage have to be substantially larger and heavier than a motor burning a denser fuel like kerosene or maybe liquid methane, the fuel for SpaceX's future Raptor engine.

Comment Hugos and the WSFS (Score 1) 1044

The Hugo awards are a part of the Worldcon, nominated and voted on by members of the Worldcon. Anyone can be a member of the current Worldcon by paying a membership fee. Supporting membership usually costs $40. That doesn't get you physical access to the con itself, attending membership is a lot more.

Joining the Worldcon makes you a member of the World Science Fiction Society (WSFS) for that year. As part of that membership you get nominating and voting rights for the Hugos including the right to nominate the next year but not vote. If you want to vote next year (that con will be in Kansas City in 2016) you need to pay for a supporting or attending membership for that specific convention.

I was a member of the 2014 Worldcon, nominated and voted that year and nominated this year but I couldn't vote this year since I didn't join Sasquan.

As I understand it a lot of people joined Sasquan as supporting members after the nominations closed simply to vote for the Hugos, generally opposing the slate nominees. They couldn't change the nomination lists but they could vote against the slate nominees. In the end the opposition was strong enough that most slate nominees ended up below No Award (or as David Gerrold calls it "Noah Ward").

Comment Re:the USA is Portugal (Score 3, Informative) 87

JAXA is currently flying its second asteroid material return mission, Hayabusa 2. The first was not a total success but the craft did get to its target and return a capsule to Earth. Number of NASA asteroid material return missions, zero.

Hayabusa 2 is carrying a lander built by the French CNES and three smaller "hopping" landers as well as an IED meant to blow a hole in the asteroid's surface to expose fresh material for inspection and analysis.

There's a lot of difficult science to be done (tm GlaDOS) out in the solar system, we can't expect the US to do all of it.

Submission HTV-5 on its way to the ISS->

nojayuk writes: There's another launcher delivering cargo to the ISS apart from US and Russian vehicles, and it's Japanese. The fifth Koutonori (White Stork) cargo vehicle was successfully launched today at from pad 2 of the Yoshinobu Launch Complex at Tanegashima south of Tokyo at 11:50:49 UTC, carrying over 5 tonnes of food, spare parts and scientific equipment to the ISS in a pressurised cabin and an external racking system. This is the fifth successful launch in a row for the Japanese H2B launcher. The Koutonoris have carried over 20 tonnes of cargo in total to the ISS, more than double the amount of SpaceX's six successful CRS resupply flights.
Link to Original Source

Comment Re:Sell batteries as an end product (Score 1) 232

There are also satchel charges which can be, in extremis, thrown a certain distance by hand so they could be classed as "large hand grenades", I suppose. On the other hand there's the Special Atomic Demolition Munition which was (theoretically) man-portable...

I suspect that large Li-ion technology cells are used in certain circumstances such as submarines but not usually in "civilian" environments like cars because of Li-ion's ability to release its stored energy in a short period of time as heat or even a low-order explosion due to its low internal resistance. A rough calculation suggests a fully charged Li-ion battery holds about 15% of the energy of a similar mass of TNT. Building a battery pack out of a lot of smaller cells extends the time for a fire to propagate and engage neighbouring cells. A few large cells each storing several megajoules of energy are more likely to burn faster (the square/cube law at work) and set off their neighbours similarly.

Comment Re:Sell batteries as an end product (Score 2) 232

My understanding is that the Tesla car batteries are built from large arrays of commodity Li-ion battery cells, they're nothing special in terms of capacity or size or design. An 80kWh Tesla battery pack might have ten thousand cells each of which is a 3.7V 2.2AH unit of the sort you'd find in a laptop battery pack, arranged in series-parallel.

Tesla's "secret sauce" is the charging and conditioning of their batteries as well as armouring them against damage in a collision and preventing propagation of a fire in a series of cells spreading too quickly to the other cells in the pack.

Making Li battery cells in the Musk Gigafactory will bring the cost down a bit, cutting out the middleman as Henry Ford did but I don't expect them to change the design much, for safety reasons if nothing else. Battery makers don't sell large Li-ion cells for the same reason they don't sell large hand-grenades...

Comment Re:Just another case.... (Score 4, Interesting) 184

We did workarounds on the ATA bus spec for known hardware bugs in older VIA chipsets. These were silicon bugs, not chipset firmware so they couldn't be fixed afterwards with patches and there were millions of these boards out there. Declaring our devices (CD-ROM and DVD-ROM drives) wouldn't work with these boards was not going to happen for sales reasons so our code included a lockup-recovery function that was invoked when the rare bug conditions were met and the IDE bus froze. The average user never noticed these lockups and we didn't tell them about them.

Out-of-spec bugs like this were well-known in the industry and workarounds were easy to produce as long as you had access to a few million bucks worth of test equipment and a good team of professional engineers with decades of experience, not something that's common in the Linux world.

Comment Re:In other news... (Score 1) 484

Right now, as I type this, France is importing 2.5GW of electricity from Germany and 450MW from Switzerland. It is exporting 2GW to Britain, 2.6GW to Italy and 890MW to Spain though, a next export from France of 3GW.

You can find real-time details of France's generating capacity, imports and exports at this website,

I've seen times on this page when France has been exporting as much as 10GW of electricity to other countries (Britain in particular takes 2GW of cheap French nuclear electricity nearly all the time). I don't think I've ever seen a case where France was importing more electricity than it exported.

"I'm not afraid of dying, I just don't want to be there when it happens." -- Woody Allen