102 research outputs found
Gegevens betreffende optredende ruwheidswaarden voor de weerstand die het water in watergangen tengevolge van plantengroei ondervindt
Resultaten van wandruwheidsmetingen in een aantal leidingen van het waterschap "De Oostermoersche Vaart" in Drenthe
Op de voorgrond stond de invloed van het gedrag van een in de tijd toenemende begroeiing in open leidingen op de stromingsweerstand. Het begroeid raken van leidingen heeft tot gevolg dat bij een bepaalde afvoer het waterpeil zich hoger instelt dan wanneer die afvoer door een schone leiding zou plaats vinden
Asymptotic Dynamics of Breathers in Fermi-Pasta-Ulam Chains
We study the asymptotic dynamics of breathers in finite Fermi-Pasta-Ulam
chains at zero and non-zero temperatures. While such breathers are essentially
stationary and very long-lived at zero temperature, thermal fluctuations tend
to lead to breather motion and more rapid decay
Analyse van de onderhoudskosten van leidingen, in enkele Drenthse waterschappen over het jaar 1963
De Te verwachten verkeersbelasting van landbouwwegen bij wel en niet verplaatsen van boerderijen, in het bijzonder voor een weg in de ruilverkaveling in voorbereiding "Rolde"
Tunneling of quantum rotobreathers
We analyze the quantum properties of a system consisting of two nonlinearly
coupled pendula. This non-integrable system exhibits two different symmetries:
a permutational symmetry (permutation of the pendula) and another one related
to the reversal of the total momentum of the system. Each of these symmetries
is responsible for the existence of two kinds of quasi-degenerated states. At
sufficiently high energy, pairs of symmetry-related states glue together to
form quadruplets. We show that, starting from the anti-continuous limit,
particular quadruplets allow us to construct quantum states whose properties
are very similar to those of classical rotobreathers. By diagonalizing
numerically the quantum Hamiltonian, we investigate their properties and show
that such states are able to store the main part of the total energy on one of
the pendula. Contrary to the classical situation, the coupling between pendula
necessarily introduces a periodic exchange of energy between them with a
frequency which is proportional to the energy splitting between
quasi-degenerated states related to the permutation symmetry. This splitting
may remain very small as the coupling strength increases and is a decreasing
function of the pair energy. The energy may be therefore stored in one pendulum
during a time period very long as compared to the inverse of the internal
rotobreather frequency.Comment: 20 pages, 11 figures, REVTeX4 styl
Discrete breathers in polyethylene chain
The existence of discrete breathers (DBs), or intrinsic localized modes
(localized periodic oscillations of transzigzag) is shown. In the localization
region periodic contraction-extension of valence C-C bonds occurs which is
accompanied by decrease-increase of valence angles. It is shown that the
breathers present in thermalized chain and their contribution dependent on
temperature has been revealed.Comment: 5 pages, 6 figure
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