2,274 research outputs found
Redundancy Analysis of the Railway Network of Hungary
Available alternative routes on which traffic can be rerouted in the case of
disruptions are vital for transportation networks. Line sections with less
traffic under normal operational conditions but with increased importance in
the case of disruptions are identified in the railway network of Hungary by
using a weighted directed graph. To describe the goodness of the individual
alternative routes the so-called redundancy index is used. The results show
that the structure of the network is good, but the lines with the highest
redundancy (lines No. 80, 2, 4 and 77 according to the numbering of the
national railway operator, M\'AV) are mostly single tracked and in many cases
the line speed is low. The building of additional tracks and electrifying these
lines while still maintaining the existing diesel locomotives for the case of
disruptions of the electric support are the keys to make the performance of the
rather dense railway network of Hungary sustainable.Comment: 8 pages, 4 figures. arXiv admin note: text overlap with
arXiv:2005.1280
Модификация состава лесообразующих пород ЗАО Bakonyerdő в лесничестве Papa
Были исследованы медленно растущие леса из робинии псевдоакации на площади 250 га в лесничестве Pápa ЗАО Bakonyerdő на трех пробных площадях (Egyházaskesző, Kemeneshőgyész, Magyargencs). Леса на выбранных ПП достигнут возраста рубки в течение следующего 10-летнего периода лесной таксации. Задачей работы было выяснение взаимосвязи между параметрами древостоя и индексами выхода древесины
Financial correlations at ultra-high frequency: theoretical models and empirical estimation
A detailed analysis of correlation between stock returns at high frequency is
compared with simple models of random walks. We focus in particular on the
dependence of correlations on time scales - the so-called Epps effect. This
provides a characterization of stochastic models of stock price returns which
is appropriate at very high frequency.Comment: 22 pages, 8 figures, 1 table, version to appear in EPJ
Simulating radiative shocks in nozzle shock tubes
We use the recently developed Center for Radiative Shock Hydrodynamics
(CRASH) code to numerically simulate laser-driven radiative shock experiments.
These shocks are launched by an ablated beryllium disk and are driven down
xenon-filled plastic tubes. The simulations are initialized by the
two-dimensional version of the Lagrangian Hyades code which is used to evaluate
the laser energy deposition during the first 1.1ns. The later times are
calculated with the CRASH code. This code solves for the multi-material
hydrodynamics with separate electron and ion temperatures on an Eulerian
block-adaptive-mesh and includes a multi-group flux-limited radiation diffusion
and electron thermal heat conduction. The goal of the present paper is to
demonstrate the capability to simulate radiative shocks of essentially
three-dimensional experimental configurations, such as circular and elliptical
nozzles. We show that the compound shock structure of the primary and wall
shock is captured and verify that the shock properties are consistent with
order-of-magnitude estimates. The produced synthetic radiographs can be used
for comparison with future nozzle experiments at high-energy-density laser
facilities.Comment: submitted to High Energy Density Physic
The particle spectrum of the Tricritical Ising Model with spin reversal symmetric perturbations
We analyze the evolution of the particle spectrum of the Tricritical Ising
Model by varying the couplings of the energy and vacancy density fields. The
particle content changes from the spectrum of a supersymmetric theory (either
of an exact or a spontaneously broken supersymmetric theory) to the spectrum of
seven particles related to the underlying E_7 structure. In the low temperature
phase some of these excitations are topologically charged particles that are
stable under an arbitrary variation of the parameters. The high and low
temperature phases of the model are related by duality. In some regions of the
two couplings there are also present false vacua and sequences of bound states.
In order to study the non-integrable features of this model we employ the Form
Factor Perturbation Theory and the Truncated Conformal Space Approach.Comment: 34 pages, 14 figures, text misprints correcte
Erlang Code Evolution Control
During the software lifecycle, a program can evolve several times for
different reasons such as the optimisation of a bottle-neck, the refactoring of
an obscure function, etc. These code changes often involve several functions or
modules, so it can be difficult to know whether the correct behaviour of the
previous releases has been preserved in the new release. Most developers rely
on a previously defined test suite to check this behaviour preservation. We
propose here an alternative approach to automatically obtain a test suite that
specifically focusses on comparing the old and new versions of the code. Our
test case generation is directed by a sophisticated combination of several
already existing tools such as TypEr, CutEr, and PropEr; and other ideas such
as allowing the programmer to chose an expression of interest that must
preserve the behaviour, or the recording of the sequences of values to which
this expression is evaluated. All the presented work has been implemented in an
open-source tool that is publicly available on GitHub.Comment: Pre-proceedings paper presented at the 27th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur,
Belgium, 10-12 October 2017 (arXiv:1708.07854
Rigorous results on spontaneous symmetry breaking in a one-dimensional driven particle system
We study spontaneous symmetry breaking in a one-dimensional driven
two-species stochastic cellular automaton with parallel sublattice update and
open boundaries. The dynamics are symmetric with respect to interchange of
particles. Starting from an empty initial lattice, the system enters a symmetry
broken state after some time T_1 through an amplification loop of initial
fluctuations. It remains in the symmetry broken state for a time T_2 through a
traffic jam effect. Applying a simple martingale argument, we obtain rigorous
asymptotic estimates for the expected times ~ L ln(L) and ln() ~ L,
where L is the system size. The actual value of T_1 depends strongly on the
initial fluctuation in the amplification loop. Numerical simulations suggest
that T_2 is exponentially distributed with a mean that grows exponentially in
system size. For the phase transition line we argue and confirm by simulations
that the flipping time between sign changes of the difference of particle
numbers approaches an algebraic distribution as the system size tends to
infinity.Comment: 23 pages, 7 figure
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