Why this gift to idle tossers who profit from somebody else's creative laurels?
I think copyright should be limited the later of the author's death or 20 years after first publication. That would suit me if I was the author and should give enough time for a publisher to recoup his outlay. Anything more just panders to third party greed.
The stuff is expensive and a bear to work with (it work-hardens). As LOHAN isn't exactly massive, a light alloy T extrusion should be fine. Mount it flat side down so LOHAN's Teflon sliders can clip over the edges.
Using a T should save structural weight too as it will be stiff enough to serve as the bottom member of an I-beam. Attach it to a carbon upper member with carbon diagonals to form a 2D launch track. You only need to fatten this to a 3D structure with a triangular or diamond cross section around the electronics. Adding a carbon cross-piece to steady the wings during the climb to launch height would be sensible, but you wouldn't need more than that because once LOHAN is moving longer wing steadies become irrelevant, particularly if the front half of the launch track is a 2D structure.
For that matter, the launch rail can almost certainly be a lot shorter then you've drawn it: any longer than LOHAN herself seems like overkill to me. The air up there is too thin for aerodynamic stability to have much, if any, effect during the launch and the further she slides on the rod the more friction will slow her down.
BTW, I think you need another test rig. It would be a good idea to test the eventual launch track, whatever its design turns out to be, by using smaller rockets at ground level. They should be wingless to approximate the lack of aerodynamic stability at 90,000 ft.
... I ever met was fired from the large Govt contract I was on a bit over 30 years ago. He evidently didn't know that a COBOL paragraph falls through to the next paragraph because all his paragraphs ended with GO TO NAME-OF-NEXT-PARAGRAPH. He was famous for arriving at work late, followed by working late and claiming overtime. Other contractors who knew him said that over several years he'd never been known to deliver a working program: he'd always managed to resign before his work was tested or inspected.
Between graduation in 1988 and the present, i.e. 24 years, the only time that Cameron wasn't working for the Conservative party or in Parliament as an MP was the 7 years from 1994 until 2001 when he was a PR flack for Carlton Communications.
Unless things have changed since last time I looked, it can be a major problem finding who to contact (or sue) if you need to resolve an issue with some US-based websites.
At that time I don't believe there was any legal requirement to publish a valid street address or phone number on the website. Does American law now require websites that provide goods or services to provide this information online?
You obviously read my post before submitting yours, but look at the timestamps!
I wish I knew what is going on: I'd expect the timestamps to be added by the server, but the only way I can explain them is if they are local posting times set by the browser and you're in a different timezone to me unless, of course, you're using Winders and its suffering from the usual clock drift: my system is synced to NTP.
However, I digress. I've always assumed Niven deliberately wrote technological progress into the Known Space scenario and history line before he wrote more than one or two of the stories. The earlier, in Known Space time line, stories (Gil Hamilton, etc) only use fusion torches, then the earlier interstellar stories (Protector, The Warriors) are using Bussard ramjets or laser drives, with FTL drives following contact with the Outsiders. Putting the novels and short story collections in copyright date order, i.e. from 'World of Ptavvs' to 'Ringworld Throne', more or less confirms the hypothesis: "Ringworld" was copyrighted before "Protector" and it was copyrighted before most of the Gil Hamilton stories.
BTW, Poul Anderson's 'Tau Zero' was copyrighted a year or two after "A Gift From Earth" and so, if there was any interaction between them, Anderson got the Bussard drive idea from Niven, not the other way round.
I've been using ixquick (aka startpage) since Scroogle bit the dust. It seems to do a good job and, unlike Google and friends, doesn't store any information about its users and uses SSL encryption for search queries and results.
The rovers only have between 0.5 and 0.25 kWh per day to use for all purposes depending on the time of year. That has to keep the electronics warm, run the science instruments, cameras and radios *and* let them drive about on what's effectively a sandy beach. When you take all that into account the surprise is that they can go as far as 100m a day in midsummer, not that they are slow.
I thought the banks already provided this ability.
Simple: you set up an account for your child with zero overdraft limit. Kid empties account. Suddenly kid can't buy anything.
As has already been suggested its a very old idea: much older by far than the concept of an overdraft, so the idea of patenting it is simply ludicrous.
"coal - which the UK can exploit for several hundred years using current technology." NOT.
UK coal production peaked in 1913. Its decline since then is due as much to seams being worked out as to changes in technology and the fuel du jour. At current usage rates in 2008 there were said to be 250-300 years global reserves of coal.
- New Scientist, vol 197, no 2639, 19 Jan 2008 page 38
Those global reserves are known to be overestimates, but lets use them. The kicker is 'at current usage rates' : kick in a 2% year-on year increase and suddenly all that coal will be gone in 80 years. Now consider that the reserves are over-estimates and that annual usage growth probably exceeds 2% and where's your "several hundred years of coal for the UK" gone, Andrew?
Apart from GPS there are at least three alternative time sources:
- NTP. You DON'T need to connect your highly secure financial system to the net to use it. Run an NTP server on a 'net connected box and let it pretend to be a GPS receiver: every second it sends an NMEA GPRMC sentence to your secure network via a serial (RS-232) connection.
- MSF60 (UK) and DCF77 (German) low frequency time signals
- WWF and other short wave signals. The noticeable absence from this band is the UK
If accurate timing is critical for your application then you're an idiot to rely on just one, especially when receivers are relatively cheap (MSF60 receivers are cheap enough to fit in a 15 quid wall clock), so use at least two and plumb them into a local ntp time server - this way you won't be caught out by jammers or the big one if when a solar flare takes out GPS, Galileo *and* GLONASS.
Keeping LORAN alive as a GPS backup would be a smart move for shipping and airlines too.
Is there any reliable data on just how big one of the balloons can get? If not, are they so expensive that you couldn't slowly inflate one with air on the ground and track how big it gets before it bursts?
It seems to me that this is essential data because the beam length needs to be at least twice the burst size of a balloon. Three times would be better if LOHAN is to have a good chance at a vertical launch without hitting one of the balloons.
Now that modern CPUs can adjust their clock speed and number of active cores to match the load the situation with regard to 'free CPU cycles' has changed. Back in the day of P3 and P4 chips the CPU ran at the same speed and used the same amount of power regardless of whether it was working hard or twiddling its thumbs, so it made sense to donate the idle cycles to something like SETI@home or MalariaControl.
However, now there are no 'free CPU cycles' because the clock slows down and cores are stopped instead of being left to spin in idle.
I've just upgraded my old P3 box, which ran at a fixed speed, by replacing it with a dual core Athlon system, which does all that good frequency stepping and shuts down the second core when its not needed. I haven't measured its power consumption yet, but the effect is highly audible: once the OS had been installed and tweaked to match my workload it was pleasantly quiet - until I enabled BOINC, which masterminds the use of 'free cycles' to, in my case, run SETI@home and MalariaControl. The box promptly ramped up to full power, complete with howling fans that could be heard throughout the house. After three days of this I realised that I wasn't donating 'free cycles' at all, but instead I was paying for each one of the little buggers through the electricity meter and wear and tear on the PC. I've now deleted BOINC and the apps it managed. Result: peace, quiet and reduced running costs.
- You'll have noticed that the JPL Aerospace airship required the pilot to destroy/release the second balloon when the first burst, so I trust you have a similar automatic mechanism in mind? If not, simply looping the end of each lift line round hooks on the ends of a V, which would be pivoted in the center, may do the trick. The first balloon to burst will let the second tilt the V towards it so its line slides off its hook. Launching would probably be easier if the V is fixed during launch and unlocked a few minutes later, when its above most of the turbulence. It may benefit from a spring that's to keep it centered in turbulence but weak enough to be overcome when the whole weight of the truss comes onto the remaining balloon.
- running the lift lines up inside tubes or along masts for, say, half the length of the truss sounds like a much better stabilizer that either equalizing the lift from the two balloons (tricky in a breeze) or using a suspended weight (which wastes lifting power).
- if you have a choice, go for larger diameter thin-walled tubes, such as fishing-rod sections, rather than kite rods for making the truss. The large, thin-walled tubes are lighter and more rigid that the rather small, thick-walled ones used to make kites. Rolled balsa tubes of around 30 mm diameter might be better yet, especially if covered with doped-on tissue paper or very light glass-cloth. However they'd take time to make.
... its a WALDO, as anybody who reads classic science fiction knows. The name comes from a story of that name written in 1942 by Robert A. Heinlein. The current term for it is telemanipulator: I prefer waldo because its shorter and more memorable.
The distinction is that a robot is capable of autonomous action while a waldo is not: its sole job is to do precisely what its operator causes it to do while providing real-time visual, audio and haptic feedback.
a) the cost of the online disk array plus a geographically remote disk array, data centre and rental for enough comms bandwidth between the two to guarantee no data loss if the online array goes bang. Don't forget that the comms bandwidth must be considerably more than the disk array's average data rate in order to handle resyncs after one of the arrays has gone down and been fixed and restarted.
b) the cost of the online disk array plus a local tape system, off site storage for backed-up tape set(s) and the cost of van+driver to shuttle tapes between sites.
When you add in the cost of the remote data centre, the power it uses and the bandwidth rental, you may find the cost difference is a lot less than you expect.
"preventing emissions from landfills (what, a billion dollar dome over each one?"
Are you thick or what? Capping a landfill site with a plastic membrane doesn't cost even remotely what you think it does, but still manages to be rather an efficient methane trap. Add enough containerized motor generators to match the methane supply and connect them to the nearest electricity grid spur. Job done for a few million at most. This is known technology, so no development needed: its been in use in the more advanced nations since the early '90s. See:
That implies you have a spare keyboard and display. I bet most schools don't have the industrial quantities of them that would be needed to equip a programming class. Using Ethernet cables lets the RaspberryPis share the peripherals already attached to a roomful of working PCs and will certainly cost much less than buying the dedicated ones needed for direct attachment.
When I get hold of a RaspberryPi, I'm expecting to connect it to my local network, hide it in a corner somewhere and access it via ssh or telnet/Kermit. Apart from being able to access it from any other computer in the house, this will save both desk space and the cost of an extra keyboard and screen.
And better yet, it need cost no more than its face value plus a short Ethernet cable. Even the schools' current PC and the thing it calls an OS remain useful because the RaspberryPi needs a display and keyboard, but thats easy: use the cable to connect the two machines together and run PuTTY on the PC. Job done.
I've seen the S8E guys flying and I'm certain they get a lot more than 80m. Besides, 500g is damn heavy: if I built a 2.2m span F1A glider that weighed more than 450g I'd want to pull my head off with blunt pliers. F1A gliders are strong. They routinely take 30+G launch loads for every launch and still last for years. So, if LOHAN weighs more than 200-250g its probably overweight.
S8E is an international competition class for radio controlled rocket boost gliders. They use a single 20-40 newton-second motor, must weigh less than 300g and have a minimum wingspan of 1100mm. The aim of the event is to make a flight of precisely 360 secs, landing so the model stops with its nose as close as possible to a designated point. One point is deducted for every second of deviation from the target flight time and 10 points are deducted for every meter between the nose of the model and the target point.
"These models can reach approximately 1000 feet in 10 seconds and then glide in dead air for about 7 minutes using an E6 (20-40 n/s) motor. Typical models weigh 200 grams or less after motor burnout and are 200 square inches wing area plus or minus about 25 square inches. The smaller the model is, the higher it will boost and longer it will stay up in dead air. However, the smaller it is and the higher it boosts, the harder it is to see and control. So, eyesight is the ultimate limiting factor. A clean 200g model will boost to about 1100 feet on an AeroTech E6 motor." - from an American S8 page.
UK-centric details are here: http://www.fairocketry.org.uk/S8_glider.html
You guys should put your design team in touch with the British S8E flyers: Mike Francies, the UK S8E champion, is currently the chairman of FAI Rocketry. Contact details are on the Contacts page linked from the URL given above.
Flat spins have a lower descent rate than than a 'normal' spin, but I wouldn't know by how much. My gliding club requires that I spin a glider for recovery practise at least once a year, but I have never been in a flat spin and hope I never am: they are much more difficult to recover from.
The only aircraft I've seen in a flat spin, using only my Mk1 eyeball to observe it, has been an F1A class model glider, which are deliberately spun to get them down out of the thermal at the end of a flight. I've seen these go into a flat spin many times when the spin settings are not quite right. As it transitions from a 'normal' spin to a flat spin its descent rate is reduced a lot while the rotation rate increases dramatically. After a short while the flat spin destabilises and becomes a violent tumble which may, if you're lucky, transition back into a normal spin. The tumbling descent rate is a lot higher than during the initial spin, and if its tumbling when it hits the ground you get a lot of damage.
Flat spins, etc. may well do more damage on impact than normal spins because the rotation speed is so much higher.
Holding a constant heading and airspeed for 20-30 seconds and comparing the result computed result with the GPS or an equivalently accurate inertial system, i.e. better than 5 metre accuracy, will also give a good enough windspeed to navigate by and is a method that can be fairly continuously updated. Alternatively, if either the inertial system or the GPS is working, you just fly 3-5 circles at a constant turn rate and measure the drift. Depending on turn rate, that need not take more than 5-10 minutes.
All sailplane navigation programs use the circling method to calculate wind. They update the wind vector every time you stop to circle in a thermal, and at least one of them uses the straight line method and can get an acceptable accuracy from 10 seconds of hand-flown straight, constant speed flight.
Don't forget the UAV will know its wind vector up to the point when the GPS signal gets jammed, so it should be able to get near enough to home to pick up an NDB or TACAN from its home field.
I track all my energy usage on the cost per kilowatt-hour, using a rate of 9.7 kWh/litre to convert litres of petrol into energy measured in kWh. This number comes from "Sustainable Energy - without the hot air" http://www.withouthotair.com/
Averaged over the last 12 months, I've paid 14.80 p/kWh for electricity and 13.74 p/kWh for petrol.
In other words, the cheapness or otherwise of running an electric car depends entirely on the relative efficiency of energy use by a petrol car vs. an electric one.
The second video, taken from outside the airfield, catches the touchdown perfectly. The pilot put it right on the threshold with the exact amount of flare to grease it on. Its hard to imagine how it could have been done better.
"Ward said that the grotto did want to sell tickets through Groupon, but claimed that there were issues with the voucher and they had never signed the contract."
So, why in hell is the grotto out of pocket buying toys for Goupon punter's kids? No contract = no requirement to accept the Groupon voucher.
The unasked and unanswered question is "What are Groupon doing to sort the problem out?" Saying 'sorry' really doesn't begin to match the situation, but free entry to a grotto with a train for punters and paying for the grotto's losses and damage costs might.
It certainly sounds like a bastard child of the Freedom Ship concept.
A late 90s idea, that was meant to be launched in 2001, but 10 years later they're still dicking about looking for finance and there's no sign of construction on the horizon.
I found a US source of aspirators: http://www.capitolscientific.com
They sell a Brinkman pump with a 10litre tank of water that it recirculates with an electric pump for a mere $US1850, so far too expensive for the LOHAN test, but its the only one on their catalogue that can get down to an absolute pressure of 20mBar
At the other end of the scale are a couple of plastic ones that you can run from any water supply with enough pressure and capacity to squirt 12 litres/minute through the aspirator. These cost $12.50 to $14.50, so are affordable and can get down to 64mm Hg (85 mbar) and 37mm Hg (49 mbar) respectively.
So, the $12.50 aspirator is twice as good as a fridge compressor (lowest pressure around 100mbar) while the $15 one is three times as good. I'd say go for the fridge compressors but keep the $15 aspirator in mind if the compressor doesn't do the job for some reason.
I could be entirely wrong, but I think the cold at 80,000 ft will provide more of an ignition problem than the low pressure and that, while freezing the rocket motor may be an issue, keeping the ignition battery warm enough to deliver enough amps may be the biggie.
Suggestion
Sacrifice an ignitor in order to measure the current it needs if the supplier can't tell you this, and then set up a second cold soak test to make sure you can keep the ignitor battery warm enough for long enough to deliver the required current after LOHAN reaches maximum altitude.
Size the battery to have enough capacity to keep itself warm inside its insulation for, say, twice the estimated time needed to get to 80,000 ft and still retain more than enough kick to goose the ignitor real good. I think you'll find that keeping itself warm needs more capacity than firing the ignitor and that you'll need a thermostat in the heating circuit to minimise power drain at lower altitudes. The PARIS time-to-altitude numbers should be a useful input to this capacity calculation.
Notes
Li-poly batteries don't work at all well below 25 degrees C and most other types get discouraged below zero.
Maybe a supercap, kept topped up by a lower current battery with chemistry that can deal better with lower temperatures, would work as well as a Li-poly kept at 25C. A look at the specs hints that you could charge it on the ground and forget about the top-up battery, though a top-up battery might be useful to counter any current leakage if you get condensation on the supercap and wiring as the rig gets cold. Supercaps may be lighter than Li-poly batteries (I can't find any weights), are certainly cheaper and are unlikely to be bigger.
That was me reporting what I experienced at the time. IIRC we couldn't even persuade WPW to read a document we'd written a year or so previously with WP for DOS.
I cheered when Wordperfect finally sank without trace...
... because the DOS version had the least friendly UI of just about anything I've ever used. Yes, even worse than Wordstar with its collection of dot commands borrowed from nroff. On start up the Wordperfect screen was entirely blank apart from a cryptic indication in the corner that you were at line 1 page 1, it required you to use a template to sort out its tangled mess of 4 shifts on the function keys and its idea of WYSIWYG was to stick with the same font but use colours to indicate italic, bold, etc. Some will tell you that its Reveal Codes mode was wonderful: I disagree. Essential, yes. Wonderful, no. In truth Reveal Codes was nothing but a debugger and was essential because it was all too easy to create an unprintable mess of misused formatting codes that could only be fixed with careful editing in Reveal Codes. Last but not least, the only way it could produce our company standard documents was with a large collection of custom macros that somebody had to write in house.
Word 4.0 for DOS was 100% better: faster, fairly instinctive to use, and about as WYSIWYG as a 24x80 display could get. On-screen alignment etc was good, it could show italics, underlining and bold text on screen, and it was much faster than Wordperfect on the same PC. Company standard documents? Somebody took half a day to create a style sheet. Job done.
The company I worked for at the time used both Word and Wordperfect: I never used Wordperfect if I could possibly avoid doing so.
I disliked Win Word when it appeared because it was much slower than Word for DOS, but at least it worked reliably, which was far more than could be said for the Windows Wordperfect port.
Get yourself a liter or two of acetone to pour into the dry ice chamber before adding the dry ice. Without it there will be almost no thermal conductivity between the dry ice and the steel tube and cooling down will take forever. The advice to get things cooled down before pulling vacuum is good too, but you should also think about packing steel wool into the space between the chamber wall and the rocket motor for better thermal conductivity and faster cooling.
However, two things to watch with acetone:
(1) it dissolves styrofoam instantly, so don't use any styro insulation round the acetone jacket. Wrapping the dry ice container with 2-3 layers of corrugated cardboard, gluing on a ring of cardboard top and bottom and finishing with a coat of acrylic or enamel paint to keep the acetone out (both are immune to acetone) will provide plenty of insulation for the fairly short time you need to keep things cold.
Its possible that you could get away without any exterior insulation. Things will get cold enough inside the chamber without the insulation - you'll just use rather more dry ice, but its fairly cheap at around $US 2 - $US 4 a kilo and, as it sublimes at the rate of around 5 Kg / day if kept in a chilly bin, you'll probably need to buy 10 Kg or so in any case. When I used it in the lab, we always bought it as 5 lb or 10 lb chunks first thing on the day we needed it and didn't have much left at the end of the day.
(2) Acetone is very flammable, so drain it out before hitting the GO button on the rocket motor: fit a pluggable drain hole in the bottom of the dry ice compartment.
According to this site: http://www.paragoncode.com/shop/vacuum_pump/
a fridge compressor maxes out at 100mb, or about 75 mm of mercury, so its probably not good enough.
@PC Paul: if you sucked down to 15mm Hg (0.98 bar) when vac-bagging a foam wing you'd end up with a very thin wing. I have an AutoVac II system I bought from ASP which was set to pull 5" (128mm) of mercury when I got it (0.16 bar): that's plenty for vac-bagging wings. I vac-form carbon shells on Dow blue foam male moulds and pull about 11" (0.36 bar) but this is much stiffer foam than anything you'd make a wing out of: its sold for under-floor insulation and is rated to support something like 260kG/m^2 load with a hard floor surface on top of it to spread the load.
..or they'd have known that DEP is irrelevant to the Java JVM. The JVM works by interpreting bytecode (and for all I know single-steps JIT output since that would still be a lot faster than bytecode interpretation) which means that:
(1) the bytecode generated by javac is just data to the host OS since it can't be run by the OS. All that can happen to it is to get read as data and interpreted by the JVM, which IS a binary executable within the meaning of the act. The OS neither knows not cares that bytecode is going to be interpreted by the JVM. Since the JVM reads the byte code as data and will apply its own rules to prevent access outside the memory regions the JVM has allocated as stack and heap data space, DEP is simply irrelevant.
(2) the JVM allocates and manages all access to memory containing byte code, the stack and heap, ASLR rules also become somewhat irrelevant since the JVM interpreter will use ASLR in OSes that support the facility and, anyway, applies its own sanity checks first, so it will spot an out of limits data reference before it gets bounced off the ASLR gatekeeper.
(2) the JVM is a normal executable that happens to do a number of things as the result of reading the bytecode - WHICH DOESN'T MAKE THE BYTECODE EXECUTABLE TO THE OS
Cameron is right too: implementing DEP and ASLR checks over the head of any program (user-land or not) is entirely OS business: any OS that leaves these checks to a program its running is shockingly badly designed.
This isn't exactly recent news either, boys and girls: mainframes have done this since 1964. No, I don't mean the IBM S/360 schlock, but the ICL 1900 series, which always used zero-based addressing within a program regardless of the address a program was loaded at: the OS knew the datum and limit values for every program and restricted all program addressing (for both data and instructions) to that range - and yes, even in the 60s a running program could be and typically was moved in memory while it was running and could also be stopped, swapped out to disk and back in to (probably) a different memory region without knowing that it had been stopped or moved.
Photons can be made to follow an optical fibre if the angle they make with the sides of the fibre is low enough for them to all be reflected back into the cable.
However, neutrinos are particles that barely interact with other particles enough to be detected, which is why they can travel 732 km through solid rock. The chances of reliably deflecting such a beam in a circle are approximately zero. Similarly, they carry no electric charge so magnets won't deflect them either.
To show how unreactive neutrinos are, Its been calculated that a neutrino beam can penetrate a lightyear of solid lead without loosing more than a few percent of its brightness and they can whistle through the sun almost without noticing that it was there.
So, as collisions don't deflect them, they can't be reflected by anything, and magnets or electric fields don't affect them, you have no choice except to design the experiment around measuring a straight beam on neutrinos.
A good summary of the situation. Many thanks for writing it.
There's just one thing I'd like to know: why was this flood so much worse that others in previous years? I know that the area around Bankok is like a billiards table but I wonder what has been happening upstream that may have made those floods more severe.
BTW, I remember the semiconductor manufacture problems after Kyoto, but I thought the factory was the source of the casting resin used to make plastic-encapsulated chip packages.
Some time ago I was developing on a Stratus box that shared a server room and mains connection with a Tandem Non-Stop box. Both are fault tolerant machines.
We came in one Monday to find that our Stratus was dead. It turned out that the Tandem PSU had shorted during the weekend which tripped out the mains, shutting down the 2nd half of the Tandem PSU and leaving the Stratus to run on its backup battery until that went flat after 3 hours or so.
Exactly the same thing happened again a month later, proving it was no fluke.
Moral: if the backup(s) aren't in different buildings which are connected to different substations and standby generators the system can't be considered fault tolerant - and still may not be due to other circumstances.
If NHS use of N3 keeps J.Random Civil-Servant's hands off my data, which I assume it does, but use of PSN or merging N3 into PSN can't guarantee the same level of protection, then I'm totally against any use of PSN by the NHS.
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Page:
Looks OK except for copyright extension
Why this gift to idle tossers who profit from somebody else's creative laurels?
I think copyright should be limited the later of the author's death or 20 years after first publication. That would suit me if I was the author and should give enough time for a publisher to recoup his outlay. Anything more just panders to third party greed.
This post has been deleted by its author
Why a titanium rod?
The stuff is expensive and a bear to work with (it work-hardens). As LOHAN isn't exactly massive, a light alloy T extrusion should be fine. Mount it flat side down so LOHAN's Teflon sliders can clip over the edges.
Using a T should save structural weight too as it will be stiff enough to serve as the bottom member of an I-beam. Attach it to a carbon upper member with carbon diagonals to form a 2D launch track. You only need to fatten this to a 3D structure with a triangular or diamond cross section around the electronics. Adding a carbon cross-piece to steady the wings during the climb to launch height would be sensible, but you wouldn't need more than that because once LOHAN is moving longer wing steadies become irrelevant, particularly if the front half of the launch track is a 2D structure.
For that matter, the launch rail can almost certainly be a lot shorter then you've drawn it: any longer than LOHAN herself seems like overkill to me. The air up there is too thin for aerodynamic stability to have much, if any, effect during the launch and the further she slides on the rod the more friction will slow her down.
BTW, I think you need another test rig. It would be a good idea to test the eventual launch track, whatever its design turns out to be, by using smaller rockets at ground level. They should be wingless to approximate the lack of aerodynamic stability at 90,000 ft.
Notice the length of the video?
An accident or a message in a cage?
The most incompetent contract programmer...
... I ever met was fired from the large Govt contract I was on a bit over 30 years ago. He evidently didn't know that a COBOL paragraph falls through to the next paragraph because all his paragraphs ended with GO TO NAME-OF-NEXT-PARAGRAPH. He was famous for arriving at work late, followed by working late and claiming overtime. Other contractors who knew him said that over several years he'd never been known to deliver a working program: he'd always managed to resign before his work was tested or inspected.
Cameroonian work experience
Between graduation in 1988 and the present, i.e. 24 years, the only time that Cameron wasn't working for the Conservative party or in Parliament as an MP was the 7 years from 1994 until 2001 when he was a PR flack for Carlton Communications.
Re: WTF?
I should have thought it was obvious.
Its a day in the life of the average entrepreneur at Silicon Roundabout.
That could be difficult
Unless things have changed since last time I looked, it can be a major problem finding who to contact (or sue) if you need to resolve an issue with some US-based websites.
At that time I don't believe there was any legal requirement to publish a valid street address or phone number on the website. Does American law now require websites that provide goods or services to provide this information online?
Re: Oh, so you meant....
You obviously read my post before submitting yours, but look at the timestamps!
I wish I knew what is going on: I'd expect the timestamps to be added by the server, but the only way I can explain them is if they are local posting times set by the browser and you're in a different timezone to me unless, of course, you're using Winders and its suffering from the usual clock drift: my system is synced to NTP.
However, I digress. I've always assumed Niven deliberately wrote technological progress into the Known Space scenario and history line before he wrote more than one or two of the stories. The earlier, in Known Space time line, stories (Gil Hamilton, etc) only use fusion torches, then the earlier interstellar stories (Protector, The Warriors) are using Bussard ramjets or laser drives, with FTL drives following contact with the Outsiders. Putting the novels and short story collections in copyright date order, i.e. from 'World of Ptavvs' to 'Ringworld Throne', more or less confirms the hypothesis: "Ringworld" was copyrighted before "Protector" and it was copyrighted before most of the Gil Hamilton stories.
BTW, Poul Anderson's 'Tau Zero' was copyrighted a year or two after "A Gift From Earth" and so, if there was any interaction between them, Anderson got the Bussard drive idea from Niven, not the other way round.
Oh, so you meant....
...a Bussard ramjet! Why not simply say so.
Bussard ramjets make many appearances in Niven's "Tales of Known Space" series of novels and short stories as well as Poul Anderson's "Tau Zero".
Film, so it is real
There's film of the flight. It includes footage of Joe Kittinger, who is an adviser on this project. Here's the link:
http://www.redbullstratos.com
I've been using ixquick (aka startpage) since Scroogle bit the dust. It seems to do a good job and, unlike Google and friends, doesn't store any information about its users and uses SSL encryption for search queries and results.
... and have very little available power
The rovers only have between 0.5 and 0.25 kWh per day to use for all purposes depending on the time of year. That has to keep the electronics warm, run the science instruments, cameras and radios *and* let them drive about on what's effectively a sandy beach. When you take all that into account the surprise is that they can go as far as 100m a day in midsummer, not that they are slow.
I thought the banks already provided this ability.
Simple: you set up an account for your child with zero overdraft limit. Kid empties account. Suddenly kid can't buy anything.
As has already been suggested its a very old idea: much older by far than the concept of an overdraft, so the idea of patenting it is simply ludicrous.
Bollocks
"coal - which the UK can exploit for several hundred years using current technology." NOT.
UK coal production peaked in 1913. Its decline since then is due as much to seams being worked out as to changes in technology and the fuel du jour. At current usage rates in 2008 there were said to be 250-300 years global reserves of coal.
- New Scientist, vol 197, no 2639, 19 Jan 2008 page 38
Those global reserves are known to be overestimates, but lets use them. The kicker is 'at current usage rates' : kick in a 2% year-on year increase and suddenly all that coal will be gone in 80 years. Now consider that the reserves are over-estimates and that annual usage growth probably exceeds 2% and where's your "several hundred years of coal for the UK" gone, Andrew?
Relying on just GPS for timing is stupid
Apart from GPS there are at least three alternative time sources:
- NTP. You DON'T need to connect your highly secure financial system to the net to use it. Run an NTP server on a 'net connected box and let it pretend to be a GPS receiver: every second it sends an NMEA GPRMC sentence to your secure network via a serial (RS-232) connection.
- MSF60 (UK) and DCF77 (German) low frequency time signals
- WWF and other short wave signals. The noticeable absence from this band is the UK
If accurate timing is critical for your application then you're an idiot to rely on just one, especially when receivers are relatively cheap (MSF60 receivers are cheap enough to fit in a 15 quid wall clock), so use at least two and plumb them into a local ntp time server - this way you won't be caught out by jammers or the big one if when a solar flare takes out GPS, Galileo *and* GLONASS.
Keeping LORAN alive as a GPS backup would be a smart move for shipping and airlines too.
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Data! we need data!Martin Gregorie
Is there any reliable data on just how big one of the balloons can get? If not, are they so expensive that you couldn't slowly inflate one with air on the ground and track how big it gets before it bursts?
It seems to me that this is essential data because the beam length needs to be at least twice the burst size of a balloon. Three times would be better if LOHAN is to have a good chance at a vertical launch without hitting one of the balloons.
Re: How do JPA do it?
Just what I was going to say. So, ask them.
Worst thing that can happen: they won't tell you.
'Idle' computer power isn't so idle these days
Now that modern CPUs can adjust their clock speed and number of active cores to match the load the situation with regard to 'free CPU cycles' has changed. Back in the day of P3 and P4 chips the CPU ran at the same speed and used the same amount of power regardless of whether it was working hard or twiddling its thumbs, so it made sense to donate the idle cycles to something like SETI@home or MalariaControl.
However, now there are no 'free CPU cycles' because the clock slows down and cores are stopped instead of being left to spin in idle.
I've just upgraded my old P3 box, which ran at a fixed speed, by replacing it with a dual core Athlon system, which does all that good frequency stepping and shuts down the second core when its not needed. I haven't measured its power consumption yet, but the effect is highly audible: once the OS had been installed and tweaked to match my workload it was pleasantly quiet - until I enabled BOINC, which masterminds the use of 'free cycles' to, in my case, run SETI@home and MalariaControl. The box promptly ramped up to full power, complete with howling fans that could be heard throughout the house. After three days of this I realised that I wasn't donating 'free cycles' at all, but instead I was paying for each one of the little buggers through the electricity meter and wear and tear on the PC. I've now deleted BOINC and the apps it managed. Result: peace, quiet and reduced running costs.
Looks like a good design.
However, one or two suggestions:
- You'll have noticed that the JPL Aerospace airship required the pilot to destroy/release the second balloon when the first burst, so I trust you have a similar automatic mechanism in mind? If not, simply looping the end of each lift line round hooks on the ends of a V, which would be pivoted in the center, may do the trick. The first balloon to burst will let the second tilt the V towards it so its line slides off its hook. Launching would probably be easier if the V is fixed during launch and unlocked a few minutes later, when its above most of the turbulence. It may benefit from a spring that's to keep it centered in turbulence but weak enough to be overcome when the whole weight of the truss comes onto the remaining balloon.
- running the lift lines up inside tubes or along masts for, say, half the length of the truss sounds like a much better stabilizer that either equalizing the lift from the two balloons (tricky in a breeze) or using a suspended weight (which wastes lifting power).
- if you have a choice, go for larger diameter thin-walled tubes, such as fishing-rod sections, rather than kite rods for making the truss. The large, thin-walled tubes are lighter and more rigid that the rather small, thick-walled ones used to make kites. Rolled balsa tubes of around 30 mm diameter might be better yet, especially if covered with doped-on tissue paper or very light glass-cloth. However they'd take time to make.
That's no ROBOT...
... its a WALDO, as anybody who reads classic science fiction knows. The name comes from a story of that name written in 1942 by Robert A. Heinlein. The current term for it is telemanipulator: I prefer waldo because its shorter and more memorable.
The distinction is that a robot is capable of autonomous action while a waldo is not: its sole job is to do precisely what its operator causes it to do while providing real-time visual, audio and haptic feedback.
A proper price comparison could be interesting
That would be one that compares:
a) the cost of the online disk array plus a geographically remote disk array, data centre and rental for enough comms bandwidth between the two to guarantee no data loss if the online array goes bang. Don't forget that the comms bandwidth must be considerably more than the disk array's average data rate in order to handle resyncs after one of the arrays has gone down and been fixed and restarted.
b) the cost of the online disk array plus a local tape system, off site storage for backed-up tape set(s) and the cost of van+driver to shuttle tapes between sites.
When you add in the cost of the remote data centre, the power it uses and the bandwidth rental, you may find the cost difference is a lot less than you expect.
@DaveMorris
"preventing emissions from landfills (what, a billion dollar dome over each one?"
Are you thick or what? Capping a landfill site with a plastic membrane doesn't cost even remotely what you think it does, but still manages to be rather an efficient methane trap. Add enough containerized motor generators to match the methane supply and connect them to the nearest electricity grid spur. Job done for a few million at most. This is known technology, so no development needed: its been in use in the more advanced nations since the early '90s. See:
http://www.envirowaste.co.nz/index.php?page=landfill-gas-to-power
That implies you have a spare keyboard and display. I bet most schools don't have the industrial quantities of them that would be needed to equip a programming class. Using Ethernet cables lets the RaspberryPis share the peripherals already attached to a roomful of working PCs and will certainly cost much less than buying the dedicated ones needed for direct attachment.
When I get hold of a RaspberryPi, I'm expecting to connect it to my local network, hide it in a corner somewhere and access it via ssh or telnet/Kermit. Apart from being able to access it from any other computer in the house, this will save both desk space and the cost of an extra keyboard and screen.
I agree
And better yet, it need cost no more than its face value plus a short Ethernet cable. Even the schools' current PC and the thing it calls an OS remain useful because the RaspberryPi needs a display and keyboard, but thats easy: use the cable to connect the two machines together and run PuTTY on the PC. Job done.
Hey, I've got a great idea
Sell licenses to hunt the poachers, thus killing two birds with one stone.
Besides, it makes the hunt a bit more even handed if the game can shoot back.
Agree about the altitude
I've seen the S8E guys flying and I'm certain they get a lot more than 80m. Besides, 500g is damn heavy: if I built a 2.2m span F1A glider that weighed more than 450g I'd want to pull my head off with blunt pliers. F1A gliders are strong. They routinely take 30+G launch loads for every launch and still last for years. So, if LOHAN weighs more than 200-250g its probably overweight.
S8E is an international competition class for radio controlled rocket boost gliders. They use a single 20-40 newton-second motor, must weigh less than 300g and have a minimum wingspan of 1100mm. The aim of the event is to make a flight of precisely 360 secs, landing so the model stops with its nose as close as possible to a designated point. One point is deducted for every second of deviation from the target flight time and 10 points are deducted for every meter between the nose of the model and the target point.
"These models can reach approximately 1000 feet in 10 seconds and then glide in dead air for about 7 minutes using an E6 (20-40 n/s) motor. Typical models weigh 200 grams or less after motor burnout and are 200 square inches wing area plus or minus about 25 square inches. The smaller the model is, the higher it will boost and longer it will stay up in dead air. However, the smaller it is and the higher it boosts, the harder it is to see and control. So, eyesight is the ultimate limiting factor. A clean 200g model will boost to about 1100 feet on an AeroTech E6 motor." - from an American S8 page.
UK-centric details are here: http://www.fairocketry.org.uk/S8_glider.html
You guys should put your design team in touch with the British S8E flyers: Mike Francies, the UK S8E champion, is currently the chairman of FAI Rocketry. Contact details are on the Contacts page linked from the URL given above.
HTH
Flat spins have a lower descent rate than than a 'normal' spin, but I wouldn't know by how much. My gliding club requires that I spin a glider for recovery practise at least once a year, but I have never been in a flat spin and hope I never am: they are much more difficult to recover from.
The only aircraft I've seen in a flat spin, using only my Mk1 eyeball to observe it, has been an F1A class model glider, which are deliberately spun to get them down out of the thermal at the end of a flight. I've seen these go into a flat spin many times when the spin settings are not quite right. As it transitions from a 'normal' spin to a flat spin its descent rate is reduced a lot while the rotation rate increases dramatically. After a short while the flat spin destabilises and becomes a violent tumble which may, if you're lucky, transition back into a normal spin. The tumbling descent rate is a lot higher than during the initial spin, and if its tumbling when it hits the ground you get a lot of damage.
Flat spins, etc. may well do more damage on impact than normal spins because the rotation speed is so much higher.
Thw wind vector is easy enough to calculate
Holding a constant heading and airspeed for 20-30 seconds and comparing the result computed result with the GPS or an equivalently accurate inertial system, i.e. better than 5 metre accuracy, will also give a good enough windspeed to navigate by and is a method that can be fairly continuously updated. Alternatively, if either the inertial system or the GPS is working, you just fly 3-5 circles at a constant turn rate and measure the drift. Depending on turn rate, that need not take more than 5-10 minutes.
All sailplane navigation programs use the circling method to calculate wind. They update the wind vector every time you stop to circle in a thermal, and at least one of them uses the straight line method and can get an acceptable accuracy from 10 seconds of hand-flown straight, constant speed flight.
Don't forget the UAV will know its wind vector up to the point when the GPS signal gets jammed, so it should be able to get near enough to home to pick up an NDB or TACAN from its home field.
Don't be too sure about cheap driving
I track all my energy usage on the cost per kilowatt-hour, using a rate of 9.7 kWh/litre to convert litres of petrol into energy measured in kWh. This number comes from "Sustainable Energy - without the hot air" http://www.withouthotair.com/
Averaged over the last 12 months, I've paid 14.80 p/kWh for electricity and 13.74 p/kWh for petrol.
In other words, the cheapness or otherwise of running an electric car depends entirely on the relative efficiency of energy use by a petrol car vs. an electric one.
and also....
... the LOT pilot who did a superb job of putting a 767 down at Warsaw when its undercarriage failed to come down.
http://airpigz.com/blog/2011/11/2/2-videos-lot-767-lands-wheels-up-in-warsaw-poland-11-1-11.html
The second video, taken from outside the airfield, catches the touchdown perfectly. The pilot put it right on the threshold with the exact amount of flare to grease it on. Its hard to imagine how it could have been done better.
I hear that, like Sully, he is a glider pilot...
So, let me understand this...
"Ward said that the grotto did want to sell tickets through Groupon, but claimed that there were issues with the voucher and they had never signed the contract."
So, why in hell is the grotto out of pocket buying toys for Goupon punter's kids? No contract = no requirement to accept the Groupon voucher.
The unasked and unanswered question is "What are Groupon doing to sort the problem out?" Saying 'sorry' really doesn't begin to match the situation, but free entry to a grotto with a train for punters and paying for the grotto's losses and damage costs might.
Error 404 revisited
Either the URL on the last line of your article, http://iopscience.iop.org/1748-9326/6/4/044022
is incorrect or that page has been moved recently.
A Born Again Freedom Ship ?
It certainly sounds like a bastard child of the Freedom Ship concept.
A late 90s idea, that was meant to be launched in 2001, but 10 years later they're still dicking about looking for finance and there's no sign of construction on the horizon.
For your records
I found a US source of aspirators: http://www.capitolscientific.com
They sell a Brinkman pump with a 10litre tank of water that it recirculates with an electric pump for a mere $US1850, so far too expensive for the LOHAN test, but its the only one on their catalogue that can get down to an absolute pressure of 20mBar
At the other end of the scale are a couple of plastic ones that you can run from any water supply with enough pressure and capacity to squirt 12 litres/minute through the aspirator. These cost $12.50 to $14.50, so are affordable and can get down to 64mm Hg (85 mbar) and 37mm Hg (49 mbar) respectively.
So, the $12.50 aspirator is twice as good as a fridge compressor (lowest pressure around 100mbar) while the $15 one is three times as good. I'd say go for the fridge compressors but keep the $15 aspirator in mind if the compressor doesn't do the job for some reason.
Cold batteries won't start rockets
I could be entirely wrong, but I think the cold at 80,000 ft will provide more of an ignition problem than the low pressure and that, while freezing the rocket motor may be an issue, keeping the ignition battery warm enough to deliver enough amps may be the biggie.
Suggestion
Sacrifice an ignitor in order to measure the current it needs if the supplier can't tell you this, and then set up a second cold soak test to make sure you can keep the ignitor battery warm enough for long enough to deliver the required current after LOHAN reaches maximum altitude.
Size the battery to have enough capacity to keep itself warm inside its insulation for, say, twice the estimated time needed to get to 80,000 ft and still retain more than enough kick to goose the ignitor real good. I think you'll find that keeping itself warm needs more capacity than firing the ignitor and that you'll need a thermostat in the heating circuit to minimise power drain at lower altitudes. The PARIS time-to-altitude numbers should be a useful input to this capacity calculation.
Notes
Li-poly batteries don't work at all well below 25 degrees C and most other types get discouraged below zero.
Maybe a supercap, kept topped up by a lower current battery with chemistry that can deal better with lower temperatures, would work as well as a Li-poly kept at 25C. A look at the specs hints that you could charge it on the ground and forget about the top-up battery, though a top-up battery might be useful to counter any current leakage if you get condensation on the supercap and wiring as the rig gets cold. Supercaps may be lighter than Li-poly batteries (I can't find any weights), are certainly cheaper and are unlikely to be bigger.
They want an absolute pressure of 15mm Hg inside the chamber, not a 15mm reduction from atmospheric pressure.
"Please see Novell v Microsoft" - Why?
That was me reporting what I experienced at the time. IIRC we couldn't even persuade WPW to read a document we'd written a year or so previously with WP for DOS.
I cheered when Wordperfect finally sank without trace...
... because the DOS version had the least friendly UI of just about anything I've ever used. Yes, even worse than Wordstar with its collection of dot commands borrowed from nroff. On start up the Wordperfect screen was entirely blank apart from a cryptic indication in the corner that you were at line 1 page 1, it required you to use a template to sort out its tangled mess of 4 shifts on the function keys and its idea of WYSIWYG was to stick with the same font but use colours to indicate italic, bold, etc. Some will tell you that its Reveal Codes mode was wonderful: I disagree. Essential, yes. Wonderful, no. In truth Reveal Codes was nothing but a debugger and was essential because it was all too easy to create an unprintable mess of misused formatting codes that could only be fixed with careful editing in Reveal Codes. Last but not least, the only way it could produce our company standard documents was with a large collection of custom macros that somebody had to write in house.
Word 4.0 for DOS was 100% better: faster, fairly instinctive to use, and about as WYSIWYG as a 24x80 display could get. On-screen alignment etc was good, it could show italics, underlining and bold text on screen, and it was much faster than Wordperfect on the same PC. Company standard documents? Somebody took half a day to create a style sheet. Job done.
The company I worked for at the time used both Word and Wordperfect: I never used Wordperfect if I could possibly avoid doing so.
I disliked Win Word when it appeared because it was much slower than Word for DOS, but at least it worked reliably, which was far more than could be said for the Windows Wordperfect port.
Tech stock? Really?
Like hell Groupon is a tech stock. Its a coupon discount sales operation, pure and simple.
Keep up there.
Don'r forget the acetone
Get yourself a liter or two of acetone to pour into the dry ice chamber before adding the dry ice. Without it there will be almost no thermal conductivity between the dry ice and the steel tube and cooling down will take forever. The advice to get things cooled down before pulling vacuum is good too, but you should also think about packing steel wool into the space between the chamber wall and the rocket motor for better thermal conductivity and faster cooling.
However, two things to watch with acetone:
(1) it dissolves styrofoam instantly, so don't use any styro insulation round the acetone jacket. Wrapping the dry ice container with 2-3 layers of corrugated cardboard, gluing on a ring of cardboard top and bottom and finishing with a coat of acrylic or enamel paint to keep the acetone out (both are immune to acetone) will provide plenty of insulation for the fairly short time you need to keep things cold.
Its possible that you could get away without any exterior insulation. Things will get cold enough inside the chamber without the insulation - you'll just use rather more dry ice, but its fairly cheap at around $US 2 - $US 4 a kilo and, as it sublimes at the rate of around 5 Kg / day if kept in a chilly bin, you'll probably need to buy 10 Kg or so in any case. When I used it in the lab, we always bought it as 5 lb or 10 lb chunks first thing on the day we needed it and didn't have much left at the end of the day.
(2) Acetone is very flammable, so drain it out before hitting the GO button on the rocket motor: fit a pluggable drain hole in the bottom of the dry ice compartment.
What to expect from a fridge compressor
According to this site: http://www.paragoncode.com/shop/vacuum_pump/
a fridge compressor maxes out at 100mb, or about 75 mm of mercury, so its probably not good enough.
@PC Paul: if you sucked down to 15mm Hg (0.98 bar) when vac-bagging a foam wing you'd end up with a very thin wing. I have an AutoVac II system I bought from ASP which was set to pull 5" (128mm) of mercury when I got it (0.16 bar): that's plenty for vac-bagging wings. I vac-form carbon shells on Dow blue foam male moulds and pull about 11" (0.36 bar) but this is much stiffer foam than anything you'd make a wing out of: its sold for under-floor insulation and is rated to support something like 260kG/m^2 load with a hard floor surface on top of it to spread the load.
Clearly the Secunia guy(s) had no clue
..or they'd have known that DEP is irrelevant to the Java JVM. The JVM works by interpreting bytecode (and for all I know single-steps JIT output since that would still be a lot faster than bytecode interpretation) which means that:
(1) the bytecode generated by javac is just data to the host OS since it can't be run by the OS. All that can happen to it is to get read as data and interpreted by the JVM, which IS a binary executable within the meaning of the act. The OS neither knows not cares that bytecode is going to be interpreted by the JVM. Since the JVM reads the byte code as data and will apply its own rules to prevent access outside the memory regions the JVM has allocated as stack and heap data space, DEP is simply irrelevant.
(2) the JVM allocates and manages all access to memory containing byte code, the stack and heap, ASLR rules also become somewhat irrelevant since the JVM interpreter will use ASLR in OSes that support the facility and, anyway, applies its own sanity checks first, so it will spot an out of limits data reference before it gets bounced off the ASLR gatekeeper.
(2) the JVM is a normal executable that happens to do a number of things as the result of reading the bytecode - WHICH DOESN'T MAKE THE BYTECODE EXECUTABLE TO THE OS
Cameron is right too: implementing DEP and ASLR checks over the head of any program (user-land or not) is entirely OS business: any OS that leaves these checks to a program its running is shockingly badly designed.
This isn't exactly recent news either, boys and girls: mainframes have done this since 1964. No, I don't mean the IBM S/360 schlock, but the ICL 1900 series, which always used zero-based addressing within a program regardless of the address a program was loaded at: the OS knew the datum and limit values for every program and restricted all program addressing (for both data and instructions) to that range - and yes, even in the 60s a running program could be and typically was moved in memory while it was running and could also be stopped, swapped out to disk and back in to (probably) a different memory region without knowing that it had been stopped or moved.
+1 signers
Thanks for the heads-up about this petition.
Because a neutrino beam can't be bent.
Photons can be made to follow an optical fibre if the angle they make with the sides of the fibre is low enough for them to all be reflected back into the cable.
However, neutrinos are particles that barely interact with other particles enough to be detected, which is why they can travel 732 km through solid rock. The chances of reliably deflecting such a beam in a circle are approximately zero. Similarly, they carry no electric charge so magnets won't deflect them either.
To show how unreactive neutrinos are, Its been calculated that a neutrino beam can penetrate a lightyear of solid lead without loosing more than a few percent of its brightness and they can whistle through the sun almost without noticing that it was there.
So, as collisions don't deflect them, they can't be reflected by anything, and magnets or electric fields don't affect them, you have no choice except to design the experiment around measuring a straight beam on neutrinos.
A good summary of the situation. Many thanks for writing it.
There's just one thing I'd like to know: why was this flood so much worse that others in previous years? I know that the area around Bankok is like a billiards table but I wonder what has been happening upstream that may have made those floods more severe.
BTW, I remember the semiconductor manufacture problems after Kyoto, but I thought the factory was the source of the casting resin used to make plastic-encapsulated chip packages.
OK, so tell me how I know
"millions of credit cards already have the technology embedded, but very few people use them or even know they're there" .
Obvious question: how do you know if a card is NFC-enabled?
Is there some sort of logo, hologram, or what?
When fault tolerant isn't
Some time ago I was developing on a Stratus box that shared a server room and mains connection with a Tandem Non-Stop box. Both are fault tolerant machines.
We came in one Monday to find that our Stratus was dead. It turned out that the Tandem PSU had shorted during the weekend which tripped out the mains, shutting down the 2nd half of the Tandem PSU and leaving the Stratus to run on its backup battery until that went flat after 3 hours or so.
Exactly the same thing happened again a month later, proving it was no fluke.
Moral: if the backup(s) aren't in different buildings which are connected to different substations and standby generators the system can't be considered fault tolerant - and still may not be due to other circumstances.
Privacy is paramount
If NHS use of N3 keeps J.Random Civil-Servant's hands off my data, which I assume it does, but use of PSN or merging N3 into PSN can't guarantee the same level of protection, then I'm totally against any use of PSN by the NHS.
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