MIFP MEMBERS' PUBLICATIONS

MEMBERS' PUBLICATIONS

<< Start < Prev 1 2 3 4 Next > End >>

Files:

  • pdf.png

    Why the Expansion of the Universe Appears to Accelerate

    Uploaded:
    17.06.13
    Modified:
    17.06.13
    File Size:
    685 KB

    Paul Smeulders


    A Speed of Light falling over time inversely proportional to the expansion of the Universe leads to an experimentally observed exponential changing of the Red Shift over time. It is necessary to re-define the Angular Impulse Momentum in order to get a consistent expansion of space on all levels. Conservation of Energy and this newly defined Angular Impulse Momentum then leads to the requirement that all clocks slow down in time inversely proportional to the Red Shift, independent of whether the Speed of Light is constant or not. From the Lorentz equation it then follows that Ex- pansion occurs over space-time and not over space alone. A steady state expansion in true time is then transformed into an exponential expansion for an observer with a local clock. A finite lifetime of the Universe is transformed to an infi- nite lifetime for these observers including elementary particles.

  • pdf.png

    On the efficiency at maximum cooling power

    Uploaded:
    04.09.13
    Modified:
    04.09.13
    File Size:
    424 KB

    Y. Apertet, H. Ouerdane, A. Michot, C. Goupil and Ph. Lecoeur

     

    The efficiency at maximum power (EMP) of heat engines operating as generators is one corner stone of finite-time thermodynamics, the Curzon-Ahlborn efficiency ηCA being considered as a universal upper bound. Yet, no valid counterpart to ηCA has been derived for the efficiency at maximum cooling power (EMCP) for heat engines operating as refrigerators. In this letter we analyse the reasons of the failure to obtain such a bound and we demonstrate that, despite the introduction of several optimisation criteria, the maximum cooling power condition should be considered as the genuine equivalent of maximum power condition in the finite-time thermodynamics frame. We then propose and discuss an analytic expression for the EMCP in the specific case of exoreversible refrigerators.

  • pdf.png

    From local force-flux relationships to internal dissipations and their impact on heat engine performance: The illustrative case of a thermoelectric generator

    Uploaded:
    04.09.13
    Modified:
    04.09.13
    File Size:
    269 KB

    Y. Apertet, H. Ouerdane, C. Goupil and Ph. Lecoeur

     

    We present an in-depth analysis of the sometimes understated role of the principle of energy conservation in linear irreversible thermodynamics. Our case study is that of a thermoelectric generator (TEG), which is a heat engine of choice in irreversible thermodynamics, owing to the coupling between the electrical and heat fluxes. We show why Onsager’s reciprocal relations must be considered locally and how internal dissipative processes emerge from the extension of these relations to a global scale: The linear behavior of a heat engine at the local scale is associated with a dissipation process that must partake in the global energy balance. We discuss the consequences of internal dissipations on the so-called efficiency at maximum power, in the light of our comparative analyses of exoreversibility and endoreversibility on the one hand and of two classes of heat engines, autonomous and periodically driven, on the other hand. Finally, basing our analysis on energy conservation, we also discuss recent works which claim the possibility to overcome the traditional boundaries on efficiency imposed by finite-time thermodynamics in thermoelectric systems with broken time-reversal symmetry; this we do by introducing a “thermal” thermopower and an “electrical” thermopower which permits an analysis of the thermoelectric response of the TEG considering a possible dissymmetry between the electrical/thermal and the thermal/electrical couplings.

  • pdf.png

    Bunching of numbers in a non-ideal roulette: the key to winning strategies

    Uploaded:
    20.01.16
    Modified:
    20.01.16
    File Size:
    2 MB

    A. V. Kavokin, A. S. Sheremet and M. Yu. Petrov

    Chances of a gambler are always lower than chances of a casino in the case of an ideal, mathematically perfect roulette, if the capital of the gambler is limited and the minimum and maximum allowed bets are limited by the casino. However, a realistic roulette is not ideal: the probabilities of realisation of different numbers slightly deviate. Describing this deviation by a statistical distribution with a width δ we find a critical δ that equalizes chances of gambler and casino in the case of a simple strategy of the game: the gambler always puts equal bets to the last N numbers. For up-critical δ the expected return of the roulette becomes positive. We show that the dramatic increase of gambler's chances is a manifestation of bunching of numbers in a non-ideal roulette. We also estimate the critical starting capital needed to ensure the low risk game for an indefinite time.

<< Start < Prev 1 2 3 4 Next > End >>
Page 4 of 4
Results 31 - 34 of 34

We use cookies to improve our website and your experience when using it. Cookies used for the essential operation of the site have already been set. To find out more about the cookies we use and how to delete them, see our privacy policy.

I accept cookies from this site.

EU Cookie Directive Module Information