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Luís F. Simões

The Fantastical Promise of Reversible Computing  - Technology Review - 2 views

  • Reversible logic could cut the energy wasted by computers to zero. But significant challenges lie ahead.
  • By some estimates the difference between the amount of energy required to carry out a computation and the amount that today's computers actually use, is some eight orders of magnitude. Clearly, there is room for improvement.
  • There are one or two caveats, of course. The first is that nobody has succeeded in building a properly reversible logic gate so this work is entirely theoretical. But there are a number of computing schemes that have the potential to work like this. Thapliyal and Ranganathan point in particular to the emerging technology of quantum cellular automata and show how their approach might be applied.
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  • Ref: arxiv.org/abs/1101.4222: Reversible Logic Based Concurrent Error Detection Methodology For Emerging Nanocircuits
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    We did look at making computation powers more efficient from the bio perspective (efficiency of computations in brain). This paper was actually the base for our discussion on a new approsach to computing http://atlas.estec.esa.int/ACTwiki/images/6/68/Sarpeshkar.pdf and led to several ACT internal studies
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    here is the paper I told you about, on the computational power of analog computing: http://dx.doi.org/10.1016/0304-3975(95)00248-0 you can also get it here: http://www.santafe.edu/media/workingpapers/95-09-079.pdf
Dario Izzo

Probabilistic Logic Allows Computer Chip to Run Faster - 3 views

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    Francesco pointed out this research one year ago, we dropped it as noone was really considering it ... but in space a low CPU power consumption is crucial!! Maybe we should look back into this?
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    Q1: For the time being, for what purposes computers are mainly used on-board?
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    for navigation, control, data handling and so on .... why?
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    Well, because the point is to identify an application in which such computers would do the job... That could be either an existing application which can be done sufficiently well by such computers or a completely new application which is not already there for instance because of some power consumption constraints... Q2 would be then: for which of these purposes strict determinism of the results is not crucial? As the answer to this may not be obvious, a potential study could address this very issue. For instance one can consider on-board navigation systems with limited accuracy... I may be talking bullshit now, but perhaps in some applications it doesn't matter whether a satellite flies on the exact route but +/-10km to the left/right? ...and so on for the other systems. Another thing is understanding what exactly this probabilistic computing is, and what can be achieved using it (like the result is probabilistic but falls within a defined range of precision), etc. Did they build a complete chip or at least a sub-circiut, or still only logic gates...
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    Satellites use old CPUs also because with the trend of going for higher power modern CPUs are not very convenient from a system design point of view (TBC)... as a consequence the constraints put on on-board algorithms can be demanding. I agree with you that double precision might just not be necessary for a number of applications (navigation also), but I guess we are not talking about 10km as an absolute value, rather to a relative error that can be tolerated at level of (say) 10^-6. All in all you are right a first study should assess what application this would be useful at all.. and at what precision / power levels
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    The interest of this can be a high fault tolerance for some math operations, ... which would have for effect to simplify the job of coders! I don't think this is a good idea regarding power consumption for CPU (strictly speaking). The reason we use old chip is just a matter of qualification for space, not power. For instance a LEON Sparc (e.g. use on some platform for ESA) consumes something like 5mW/MHz so it is definitely not were an engineer will look for some power saving considering a usual 10-15kW spacecraft
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    What about speed then? Seven time faster could allow some real time navigation at higher speed (e.g. velocity of a terminal guidance for an asteroid impactor is limited to 10 km/s ... would a higher velocity be possible with faster processors?) Another issue is the radiation tolerance of the technology ... if the PCMOS are more tolerant to radiation they could get more easily space qualified.....
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    I don't remember what is the speed factor, but I guess this might do it! Although, I remember when using an IMU that you cannot have the data above a given rate (e.g. 20Hz even though the ADC samples the sensor at a little faster rate), so somehow it is not just the CPU that must be re-thought. When I say qualification I also imply the "hardened" phase.
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    I don't know if the (promised) one-order-of-magnitude improvements in power efficiency and performance are enough to justify looking into this. For once, it is not clear to me what embracing this technology would mean from an engineering point of view: does this technology need an entirely new software/hardware stack? If that were the case, in my opinion any potential benefit would be nullified. Also, is it realistic to build an entire self-sufficient chip on this technology? While the precision of floating point computations may be degraded and still be useful, how does all this play with integer arithmetic? Keep in mind that, e.g., in the Linux kernel code floating-point calculations are not even allowed/available... It is probably possible to integrate an "accelerated" low-accuracy floating-point unit together with a traditional CPU, but then again you have more implementation overhead creeping in. Finally, recent processors by Intel (e.g., the Atom) and especially ARM boast really low power-consumption levels, at the same time offering performance-boosting features such as multi-core and vectorization capabilities. Don't such efforts have more potential, if anything because of economical/industrial inertia?
Ma Ru

Goedel's Second Incompleteness Theorem Explained in Words of One Syllable - 5 views

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    "If it could be proved that two plus two is five, then it could be proved that five is not five, and then there would be no claim that could not be proved, and math would be a lot of bunk."
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    Fantastic!!!
pacome delva

Physics - Outsmarting decoherence in a trapped ion quantum computer - 0 views

  • This is the first ion trap demonstration of a set of logical gates that are universal for quantum computation
Luís F. Simões

Bitcoin P2P Currency: The Most Dangerous Project We've Ever Seen - 10 views

  • After month of research and discovery, we’ve learned the following:1. Bitcoin is a technologically sound project.2. Bitcoin is unstoppable without end-user prosecution.3. Bitcoin is the most dangerous open-source project ever created.4. Bitcoin may be the most dangerous technological project since the internet itself.5. Bitcoin is a political statement by technotarians (technological libertarians).*6. Bitcoins will change the world unless governments ban them with harsh penalties.
  • The benefits of a currency like this:a) Your coins can’t be frozen (like a Paypal account can be)b) Your coins can’t be trackedc) Your coins can’t be taxedd) Transaction costs are extremely low (sorry credit card companies)
  • An individual with the name -- or perhaps handle -- of Satoshi Nakamoto first wrote about bitcoins in a paper called Bitcoin: A Peer-to-Peer Electronic Cash System.
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  • * We made this term up to describe the “good people” of the internet who believe in the fundamental rights of individuals to be free, have free speech, fight hypocrisy and stand behind logic, technology and science over religion, political structure and tradition. These are the people who build and support things like Wikileaks, Anonymous, Linux and Wikipedia. They think that people can, and should, govern themselves. They are against external forms of control such as DRM, laws that are bought and sold by lobbyists, and religions like Scientology. They include splinter groups that enforce these ideals in the form of hacktivism, such as the takedown of the Sony Playstation Network after Sony tried to prosecute a hacker for unlocking its console.
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    Sounds good!
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    wow it's frigthening! it's the dream of every anarchist, every drug, arm, human dealer! the world made as a global fiscal paradise... the idea is clever however it will not replace real money because 1 - no one will build a fortune on bitcoin if a technological breakthrough can ruin them 2 - government never allowed parallel money to flourish on their territory, so it will be almost impossible to change bitcoin against euros or dollars
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    interesting stuff anyone read cryptonomicon by neal stephenson? similar theme.
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    :) yes. One of the comments on reddit was precisely drawing the parallels with Neal Stephenson's Snowcrash / Diamond Age / Cryptonomicon. Interesting stuff indeed. It has a lot of potential for misuse, but also opens up new possibilities. We've discussed recently how emerging technologies will drive social change. Whether it's the likes of NSA / CIA who will benefit the most from the Twitters, Facebooks and so on, by gaining greater power for control, or whether individuals are being empowered to at least an identical degree. We saw last year VISA / PayPal censoring WikiLeaks... Well, here's a way for any individual to support such an organization, in a fully anonymous and uncontrollable way...
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    One of my colleagues has made a nice, short write-up about BitCoin: http://www.pds.ewi.tudelft.nl/~victor/bitcoin.html
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    very nice analysis indeed - thanks Tamas for sharing it!
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    mmm I'm not an expert but it seemed to me that, even if these criticisms are true, there is one fundamental difference between the money you exchange on internet via your bank, and bitcoins. The first one is virtual money and the second one aims at being real, physical, money, even if digital, in the same way as banknotes, coins, or gold.
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    An algorithm wanna-be central bank issuing untraceable tax free money between internet users? not more likely than the end of the world supposed to take place tomorrow, in my opinion. Algorithms don't usually assault women though !:P
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    well, most money is anyway just virtual and only based on expectations and trust ... (see e.g. http://en.wikipedia.org/wiki/Money_supply) and thus if people trust that this "money" has some value in the sense that they can get something of value to them in exchange, then not much more is needed it seems to me ...
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    @Leopold: ok let's use the rigth words then. Bitcoin aim at being a currency ("physical objects generally accepted as a medium of exchange" from wikipedia), different than the "demand deposit". In the article proposed by Tamas he compares what cannot be compared (currencies, demand deposits and their mean of exchange). The interesting question is wether one can create a digital currency which is too difficult to counterfeit. As far as I know, there is no existing digital currency except this bitcoins (and maybe the currencies from games as second life and others, but which are of limited use in real world).
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    well of course money is trust, and even more loans and credit and even more stock and bond markets. It all represents trust and expectations. However since the first banks 500 years ago and the first loans etc. etc., and as well the fact that bonds and currencies bring down whole countries (Greece lately), and are mainly controlled by large financial centres and (central) banks, banks have always been on the winning side no matter what and that isn't going to change easily. So if you are talking about these new currencies it would be a new era, not just a new currency. So should Greece convert its debt to bitcoins ;P ?
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    well, from 1936 to 1993 the central bank of france was owned by the state and was supposed to serve the general interest...
Juxi Leitner

Soon: A robot controlled by human brain cells! : Rediff Business News, Latest India bus... - 0 views

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    Rediff Business News, Latest India business news, India Economy news, World Business, Finance news, Latest business headlines, business videos and business articles.
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    after the rat brain cells... it was logical !
ESA ACT

Goedel and his Universe - 0 views

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    written version of a nice talk on Goedel I heard at a conference. No knowledge about math needed.
ESA ACT

Technology Review: Managing Energy with Swarm Logic - 0 views

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    Self-organizing equipment could cut energy bills.
jaihobah

The Nanodevice Aiming to Replace the Field Effect Transistor - 2 views

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    very nice! "For a start, the wires operate well as switches that by some measures compare well to field effect transistors. For example they allow a million times more current to flow when they are on compared with off when operating at a voltage of about 1.5 V. "[A light effect transistor] can replicate the basic switching function of the modern field effect transistor with competitive (and potentially improved) characteristics," say Marmon and co. But they wires also have entirely new capabilities. The device works as an optical amplifier and can also perform basic logic operations by using two or more laser beams rather than one. That's something a single field effect transistor cannot do."
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    The good thing about using CdSe NW (used here) is that they show a photon-to-current efficiency window around the visible wavelengths, therefore any visible light can in principle be used in this application to switch the transistor on/off. I don't agree with the moto "Nanowires are also simpler than field effect transistors and so they're potentially cheaper and easier to make." Yes, they are simple, yet for applications, fabricating devices with them consistently is very challenging (being the research effort not cheap at all..) and asks for improvements and breakthroughs in the fabrication process.
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    any idea how the shine the light selectively to such small surfaces?
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    "Illumination sources consisted of halogen light, 532.016, 441.6, and 325 nm lasers ported through a Horiba LabRAM HR800 confocal Raman system with an internal 632.8 nm laser. Due to limited probe spacing for electrical measurements, all illumination sources were focused through a 50x long working distance (LWD) objective lens (N.A. = 0.50), except 325 nm, which went through a 10x MPLAN objective lens (N.A. = 0.25)." Laser spot size calculated from optical diffraction formula 1.22*lambda/NA
darioizzo2

Embodied Logic: Researchers Build Artificial Venus Flytrap - Tech Briefs - 1 views

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    Nice story telling. (watch the video) The materials are actually cool, but the venus flytrap pitch (hinting at a biomimetic success) or the embodied intelligence speech are "a bit" of a stretch,
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