Use the Live-CD so you can try your hardware before actually installing
1990 posts • joined 24 Mar 2010
Use the Live-CD so you can try your hardware before actually installing
A good deal of science computing is done on RHEL or spin offs
was from someone who thinks I really use Windows in secret !!
I don't need or use WIndows.
I browse the web, watch video, process RAW photo files, edit video ( 1080/50p), design pcbs, write code, model proteins, run extensive scientific calculations, scan and print ALL without the need for WIndows
is my usual one of ignoring Windows completely.
It's worked fine for the last 6 years
The figures quoted in the article suggest the amount of energy imparted to the projectile is a small proportion of the energy used so the number of shots drops even further maybe by 20 fold
~90 J from your figures - really small, far too small
~2 kJ from http://en.wikipedia.org/wiki/Muzzle_energy for a rifle bullet
They sound impressive your numbers but let's look at them at little more closely.
A 1 tonne Mach 7.5 projectile had a kinetic energy of ~3e9 J - that's 3000 MJ - that's rather out of the range of current discussion esp. if the launch efficiency is as low as the data in the article suggests.
It is hard to beat Physics
if you make it into a sieve it will sink but it seems rather far fetched to assume that it will be hit a sufficient number of times BELOW the waterline. If its a small vessel then game over and if the projectile hits something heavy or critical that it can vaporise/ be vaporised by then ditto.
100000 tons takes a lot of sinking with small holes.
Most modern warships have relatively thin hulls. Such a slim projectile needs to hit something with substantial mass to impart a good proportion of its energy otherwise it will just go through like a rifle bullet through paper. There might be local damage but it could easily be insignificant to a ship-sized object.
Its also an unguided shell equivalent so it need to follow a ballistic curve and allow for the curvature of the earth. This is likely to increase errors in aiming.
For close quarter defence there might be a different picture.
I calculate the 1 ton kinetic energy as ~1.5MJ so there is a large mismatch somewhere
(Imperial AND SI units - urrgh!!)
It is used all day - if we leave for more than a short time it's put to sleep as are the desktops if they are on. Only the low-power Atom file/odds&sods server runs all the time
What's so special about that ?
We have an old laptop running OpenSUSE 11.4 that's left on during the day and sleeps at night - it's hardly ever turned off it might be restarted once a month usually because it's been left unplugged.
That mirrors my experiences with various laptops/desktop but most often when Windows Update fails and the Recovery fails and there is, of course, no install disk. In each case a Linux Live-CD has recovered the data, and even reformatted the apparently ailing disk and the system has then gone on to a long useful Linux life. In fact I'm writing this on one now ~3 years after it's 'accident'
My normal distro is OpenSUSE. If you use the DVD download that has 3 webservers including Apache2 available on disk. They are not installed by default - why would they be but available for a few clicks.
Incidently the most dangerous contaminants of food are natural, although generally caused by poor storage etc. Materials like aflatoxins ( must be less than 20 ppb in food) make many man-made poisons, let alone food additives, look quite bland.
Carcinogens in food ARE an important issue - but are they actually a significant risk?
Lots of things are easy to measure to measure to extremely low levels e.g certain chemicals and ionizing radiation. Problem is assessing the consequences.
With carcinogens a 'predicitive' test that has been used widely is the Ames test named after its inventor, which actually show the mutagenic effect of a chemical. Find an active and the supposition was that almost no level was 'safe'
Years later Bruce Ames published a long review of carcinogenic challenges and demonstrated that biological systems have a threshold level below which almost no damage is important and the system generally self-repairs.
So carcinogens are important but the risks are probably far lower than the popular perception.
is readily available e.g.
No hardware assisted encoding but I use it for 1080/50p encoding and it works well, if rather slowly, on anything less then top-notch kit. Playback on VDPAU/Nvidia assisted decode is excellent using ~5-10% cpu even on an old dual core AMD 64
There certainly have been ARM versions
You need to use liquid crystal glasses NOT beer goggles
can produce that effect. I've spent a lot of time looking at 3D chemical graphics of various types over the last 30 years and have got used to the games they can play. If you cross your eyes or defocus them you might well find the images shift around to give the impression that you are looking from below. Try changing the size or darkening the room.
Thanks for that, pity it was so small.
Having done this quiz I guess one problem is that it isn't against the clock so I had plenty of time to scrutinize the pages and particularly the URLs. In some ways it was easy to spot the phishing sites but verifying that a genuine site was genuine was harder - spot the phish and you're done but on the 'good' sites it took more searching to convince me that there wasn't some trick.
But how many people did your survey cover ?
Not on my system mate
Just like the desktop ?
Just card in/out - no PIN
Spent ~£380 recently going Calais-Switzerland-Riviera-Auvergne-Calais with the largest single item ~£40 all without PIN or signature - I guess they have the reg. plate captured though.
Both electricity/gas I put the readings in on-line, bill gets paid by DD, meterman turns up about a week later. Being going on for ~ 2/3 years
It didn't read like a joke
sudo version 1.7.6p2
"daringly innovative; on the cutting edge. "
Your point is ?
And I have been on this site for a number of years. And there does seem to be a tendency for posters to get their facts wrong - often wildly so.
Recently someone claimed that the NEO was 6 miles in diameter where most info sources were saying ~11m or bus sized
er ? 11 metres is closer
"The asteroid, estimated to be about 11m (36ft) in diameter, was first detected on Wednesday."
"A small asteroid the size of a city bus zoomed between Earth and the moon's orbit Friday (Jan. 25)"
I agree about the nuck though
Quite the reverse.
A charged comb will lift a feather ( against the force of gravity) but the uncharged comb doesn't
I think the problem is that the rock is most to be both an irregular shape and likely to be tumbling so to attach any form of propulsion to it and then stabilize and steer it is going to be mighty hard
It does sound fanciful doesn't it ?. Nevertheless that is exactly what is being proposed in the document referenced in the article under the title "Gravity Tractor"
"..minimize fuel consumption and maximize the asteroid’s deflection? What are the trade-offs between the mass of the tractor, the distance between the tractor and the NEO, the control laws, and the time required to produce the required deflection? Reliability is a crucial issue given the long periods (several years to a decade) typically required for gravity traction to produce the required deflection. What are the requirements for autonomous spacecraft control procedures to manage hovering station keeping and maintain stability of the traction system over a long period of time in the (verynearby) presence of an irregular rotating mass?"
That is indeed what is being proposed although the object would have active propulsion to slowly 'tow' the NEO away from a collision course.
There are enough misguided souls on this site who seem to believe almost anything they are told. It's one thing to be a lively, edgy tech. site - quite another to be an off-shoot of the Daily Mail
Will you STOP using this wildly inaccurate description of the actual proposal !
e.g. the Linux kernel Oh wait !
And yet we still use it - I wonder why
As a Linux only user I might be devastated by this news except I don't use Met Office widget for Firefox anyway.
"but that involves at least one more click than usual" - er ? Bookmarks anyone ?
As for iPlayer - simples use get_iplayer instead
It's not clear to me how the layers are orientated bu it looks as though the graphene sheets are stacked "vertically" |||||| so that the water has to move along between the sheets. If these have hydrophilic groups and have dimensions that just allows water to move through the spaces then other materials may well have problems as there will be a strong tendency for water to fill the spaces and repel any other molecules. In this situation the water will behave quite differently to bulk water - it'll be more like a sloppy ice where every water molecule that evaporates from the low humidity end will need to be replaced from the high end to maintain the energetics.
I guess it well might. Even chemistry is different with deuterium. The rates of reactions are generally slower and drugs with a hydrogen replaced by deuterium at a point of metabolism are usually metabolised significantly more slowly.
So some people think that a heat shield, steering mechanism and parachutes are going to be feasible for 20000 tonnes of iron ore or whatever
To manage all the telephone sanitizers and hairdressers that'll be arriving soon after.
the article keeps banging on about mass difference e.g " live long enough to measure the positron’s mass" or "one such possibility – that matter and antimatter have different mass."
We know the mass of an electron - if the energy from electron/positron collision is not twice the equivalent of the electron mass then doesn't that give the answer directly ?
Any physicist care to comment ?
The other quote :"Cross-platform support is essential to avoid being locked into a particular technology.”
Like Office ?
Sorry I find that a poor example - the data isn't "under one roof" and available to anyone on the CERN network.
The LHC is going to generate 15PB of data per year.
Their GRID computer :-
Number of machines: 14,972 processors with 64,623 cores running Linux
Some facts about storage capacity (November 2011):
Tape: 41 PB of data, including non LHC data. (Source)
Disk: 62K hard drives with a total capacity of 62660 TiB. RAID is used to increase redundancy and stability. (Source)
That sounds like quite big data
I've noticed it too.
Maybe it's the fact that they have hardly been exposed to anything else.
When I think of the bare board micros , ROM Basic, .... Amiga, Forth, PC, Linux that I've been exposed to as an amateur let alone the terminal/mainframe, PDP11, VAX, Linux workstations and farms in my professional life I guess anyone 50+ has lived through a lot of changes.