Wikipedia:Reference desk/Archives/Computing/2012 July 27

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July 27

TBV files

Are there any avaliable programs that can extract or view .TBV files? The only one I found was unavaliable on my browser

Also in regards to my last posted question:

"Changeing words on websites - Is there any downloadable program avaliable that is capable of changing any instance of one word into another word whenever i surf the web, for example if i am browsing through random wikipedia pages the program automatically replaces any instance of the word "robin" and replaces it with the word "bird"?"

"That's something that can be done with a Greasemonkey script (such as this one) but one needs a bit of JavaScript knowledge to get it doing what you want..."

"Why would you want that? Apart from pranks, of course"

Its not for pranks, its for my own personal preferences....it won't affect the appearence of anyone else who views the same website on a separate computer, just my computer for my viewing preference. 72.235.221.120 (talk) 00:27, 27 July 2012 (UTC)

// ==UserScript==
// @name           ReplaceWord
// @include        http://en.wikipedia.org/wiki/*
// ==/UserScript==

var word = document.body.innerHTML
word=word.replace(/Robin/g,'bird');
word=word.replace(/robin/g,'bird');
document.body.innerHTML=word;

AvrillirvA (talk) 00:46, 27 July 2012 (UTC)

Note that javascript uses regular expresions so instead of

word=word.replace(/Robin/g,'bird');
word=word.replace(/robin/g,'bird');
//you can use this
word=word.replace(/[Rr]obin/g,'bird');

190.158.212.204 (talk) 05:19, 27 July 2012 (UTC)

Commons template

Does anyone here know how to modify templates on commons? It is probably a simple mod but I don't want to crash all the servers if I try it.

• http://commons.wikimedia.org/wiki/User_talk:Mdennis_(WMF)/Staff_uploads --Canoe1967 (talk) 03:20, 27 July 2012 (UTC)

Resolved

--Canoe1967 (talk) 04:16, 27 July 2012 (UTC)

Migrating from Ubuntu to Lubuntu, with version upgrade

I have a Linux machine that is currently running Ubuntu 11.04 Natty Narwhal, that I am considering migrating to Lubuntu 12.04, (corresponding to the Ubuntu Precise Pangolin LTS release). I access it using NoMachine from my Win 7 PC. I use it mostly (but not exclusively) as a server, and need a GUI.

The most important GUI applications that I will need to run are:

• Firefox with add-ons (AdBlock etc)
• Synaptic package manager
• CodeLite
• Libreoffice

The machine has been running for some years, and I've done many tweaks and fixes to config files relating to various services. I have several cron-driven scripts running. My record-keeping of the tweaks and fixes I've done is mostly non-existant. In other words, a total reinstall would be a pain.

My questions:

1. Is there a painless way to do the migration (like installing LXDE + various packages, de-installing various packages)?
2. If so, what would I need to install, and what could be removed, in order to "Lubuntify" Ubuntu?
3. If this approach is possible, I assume the most sensible thing to do is to do the migration to LXDE first, and the upgrades afterwards, correct?
4. There is an intermediate release, 11.10. Would I need to first upgrade to 11.10, then to 12.04?
5. Would the end result of such a migration be equivalent to a Lubuntu install, or would I keep some of the current bloat?
6. Do I need to (manually) change software repositories?

Thanks! -NorwegianBlue ^talk 08:57, 27 July 2012 (UTC)

Having a several-year-old machine full of undocumented changes is a situation fraught with peril no matter what you do. If the machine is doing something important, you really need to think about finding a path that will allow you to replace it when it fails, which it is bound to sooner or later. If it isn't doing anything important -- well, it really doesn't matter what you do. Looie496 (talk) 16:51, 27 July 2012 (UTC)

Well, what the machine is doing is of no great significance to mankind, but it is important to me! As I said above, the changes have not been systematically documented, regrettably. The oldest changes have survived the normal Ubuntu upgrades. I may have exaggerated the lack of documentation slightly. Every change is marked with a comment, tagged with my first name for easy grepping, and inserted blocks are marked with "#MyName INSERTION(BEGIN)", "#MyName INSERTION(END)" etc. Similar comments above and below lines in config files have been uncommented by me, and in the beginning of lines that I have commented out. The changes mostly reside in /etc. The machine is thoroughly backed up. So what I fear is not disaster, it is the amount of work involved in the migration/upgrade. I do take your message seriously, though, and will do some grepping of /etc, and write some documentation about what I've done and why, before starting the upgrade.

Of the questions above, the most important ones to me are whether the end result, if successful, is equivalent to a Lubuntu installation, and whether I need to make changes to the repositories other than those that are performed by the upgrade scripts. --NorwegianBlue ^talk 18:56, 27 July 2012 (UTC)

Well, I can't speak to this specific combination of distros, but from general Linux experience I would say almost certainly it won't work. I doubt you'll find anything anywhere that systematically removes large numbers of packages, because the dependency issues would be overwhelming. I think if you want Lubuntu, the only way to make it work is to do a reinstall -- leaving /home intact if you have it on a separate partition, as you ought to -- and then redo your customizations. I doubt you will find any other way to make this work. In future your goal should be to set things up so that you can do as much customization as possible in user space, or at least in a restricted set of files that you can copy over to a new system. Looie496 (talk) 00:36, 28 July 2012 (UTC)

Thanks! --NorwegianBlue ^talk 06:52, 28 July 2012 (UTC)

It can be done, but you'd want to do it from the command line package management programs and not from the Ubuntu GUI ones. Ideally you should consult Debian users and look for a relatively full proof (if overkill) method. ¦ Reisio (talk) 21:49, 29 July 2012 (UTC)

Thanks! I decided to follow Looie's advice, and am in the process of checking that I can get the setup working in a VirtualBox installation of Lubuntu first, meticulously taking notes... --NorwegianBlue ^talk 16:50, 30 July 2012 (UTC)

Is it possible to charge a battery from 0% to 100% instantly?

Is it possible to charge a battery from empty to full in no time (the battery goes to 100% as soon as you plug the charger)? 11:36, 27 July 2012 (UTC) — Preceding unsigned comment added by 183.81.73.132 (talk)

In general, and for all I know, for all cases, the answer is a clear no. Charging a battery tends to be about changing the chemistry of the battery. That tends to be an exothermic reaction. There are limits to the speed of charging imposed by such things as the ability of the battery to withstand the heat developed; the speed of the chemical reaction; and the ability of the anode and cathode to pass sufficient current through to cell to effect charging. --Tagishsimon (talk) 12:25, 27 July 2012 (UTC)

AFAIK instantaneity is an unphysical concept to begin with; two events occurring simultaneously are causally disconnected from one another, and do not in fact occur simultaneously from a different reference frame. If you were to substitute "in an imperceptibly small amount of time" for "instantly", then it becomes more realistic (and perhaps even possible in the real world, for some values of "imperceptible"), but there will always be some minimum amount of time required. As Tagishsimon stated, for any real battery, the speed of the chemical reaction in the battery and the heat produced by any large current are going to be limiting factors. Superconductors may resolve some of the heat problems, and the use of a capacitor in lieu of a battery can eliminate the chemical reaction speed, but an arbitrarily small charge time requires an arbitrarily large current, and even superconductors have a finite critical current density. It would probably be possible to make ultra-rapidly-charging "batteries" using such techniques, but they would almost certainly be extremely large and heavy (not to mention expensive!) and require cryogenic cooling, and eliminating the charge time entirely would simply be impossible. --Link ^(t•c•m) 13:35, 27 July 2012 (UTC)

Even charging near-instantly would be very very difficult. For instance to charge the battery from my Camera(870mAh) in the blink of an eye (1/3 seconds) would require 9396 Amps. Passing this through any circuit would generate a huge amount of heat - even a circuit with a very low resistance of 100μΩ (1/10,000 Ohms) would produce 9kw of heat - three times as much as a 3-bar electric fire; and in reality no circuit containing a battery would have such low resistance. Cheers, davidprior ^t/_c 18:51, 27 July 2012 (UTC)

To get the effect of charging instantly, without actually doing so, you can swap the uncharged batteries with charged ones, and then put the uncharged ones on the regular old charger. This approach has some promise for electric cars, where you could keep a spare set of batteries at home in order to do the swap when you come home. This would have the advantage of allowing you to drive twice as many miles in a day (say discharging one set driving to and from work and the 2nd set while going out in the evening) or allow for slower charging, which is generally better for batteries. Having some quick, hopefully automated, way to exchange the batteries is important, of course. Doing the battery swap away from home is more problematic, though, as this means you'd sometimes give your new batteries away and get weak, old batteries in their place. StuRat (talk) 18:17, 27 July 2012 (UTC)

I suppose it would be technically possible to create a very tiny battery that fully charges in under 1 second. It would likely have few practical uses though. 92.233.64.26 (talk) 15:22, 28 July 2012 (UTC)

How about a large battery consisting of many tiny cells ? Could that be charged quickly ? StuRat (talk) 20:05, 29 July 2012 (UTC)

I need to find a great Desktop sidebar with which to replace Google Desktop.

Google made the mistake of discontinuing support for Google Desktop Sidebar. It was GREAT the way it was.

Since I can't find the "Currencies" gadget anymore on it, I need to find a viable replacement that gets updated regularly. It must work on Windows 7, and be as good as Google Desktop Sidebar used to be, if not better. Please offer suggestions. Thank you. --70.179.170.114 (talk) 12:49, 27 July 2012 (UTC)

I'm afraid that our silence suggests that there isn't anything that could be considered a direct replacement. Until very recently we could have pointed you to Windows Desktop Gadgets, but Microsoft has just pulled them since they had a rather serious security flaw.

Can we ask what you hope to achieve with the gadget? You might be able to use either Google's search-box currency conversion, or an iGoogle widget, or one of these tools, or maybe you need something like a VBA macro in Excel. - Cucumber Mike (talk) 10:25, 28 July 2012 (UTC)

iGoogle will be discontinued too [1]. --NorwegianBlue ^talk 16:43, 30 July 2012 (UTC)

Two questions about cassette tapes

1. A cassette can store any kind of data, not just audio. Is it true? 2. What is the capacity (in bytes) of a regular tape?

27.65.101.220 (talk) 16:44, 27 July 2012 (UTC)

The Data recording section of the cassette tape article gives some information about it. The article suggests that regular cassette tapes could hold "up to 60 MB", and streamer cassette tapes made specially for data storage could "hold anywhere from 50 to 160 megabytes of data". These capacities seem to be based on using modern modulation techniques, so using older techniques like Kansas City standard would result in much lower capacities, probably less than 1MB per tape. AvrillirvA (talk) 16:49, 27 July 2012 (UTC)

And yes, they can store any kind of data, although you'd need a lot of cassettes, say, to store a movie (maybe a dozen for standard def, more for HD). StuRat (talk) 18:08, 27 July 2012 (UTC)

See also Digital Audio Tape. I think old floppy disks were made from similar material. One of the advanages was disks could access anywhere but tapes had to access 'linearally' from one end to the other.--Canoe1967 (talk) 18:26, 27 July 2012 (UTC)

And, of course, (magnetic) computer tapes were used for mass storage of data before either of those. I actually had an early computer which stored programs on regular cassette tapes (the Texas Instruments TI-99/4A). StuRat (talk) 18:37, 27 July 2012 (UTC)

Back in the early 80's, audio cassette tapes were the main offline storage medium used by many home computers. For example ZX Spectrum, Commodore 64, etc. For those computers, with <100KB of memory and no virtual paging, total capacity of the storage medium was never a problem. Astronaut (talk) 16:58, 30 July 2012 (UTC)