409 research outputs found
On the Power of Name-Passing Communication
It is shown that generally higher order process calculi cannot be interpreted in name-passing calculi in a robust way
Reachability in 3-VASS is in Tower
The reachability problem for vector addition systems with states (VASS) has
been shown to be \textsc{Ackermann}-complete. For every , a
completeness result for the -dimensional VASS reachability problem is not
yet available. It is shown in this paper that the -dimensional VASS
reachability problem is in \textsc{Tower}, improving upon the current best
upper bound established by Leroux and Schmidt in 2019.Comment: 24 pages, 4 figures, submitted to CONCUR 202
Analyzing Divergence for Nondeterministic Probabilistic Models
Branching and weak probabilistic bisimilarities are two well-known notions
capturing behavioral equivalence between nondeterministic probabilistic
systems. For probabilistic systems, divergence is of major concern. Recently
several divergence-sensitive refinements of branching and weak probabilistic
bisimilarities have been proposed in the literature. Both the definitions of
these equivalences and the techniques to investigate them differ significantly.
This paper presents a comprehensive comparative study on divergence-sensitive
behavioral equivalence relations that refine the branching and weak
probabilistic bisimilarities. Additionally, these equivalence relations are
shown to have efficient checking algorithms. The techniques of this paper might
be of independent interest in a more general setting
Characteristics of nonlinear terahertz-wave radiation generated by mid-infrared femtosecond pulse laser excitation
We report on efficient terahertz-wave generation in organic and inorganic crystals by nonlinear wavelength conversion approach using a 3.3 ÎŒm femtosecond pulse laser. Experimental results reveal the relation between pump power and terahertz-wave output power, which is proportional to the square of the pump power at the range of mega- to tera-watt cmâ2 class even if the pump wavelength is different. Damage threshold of organic and inorganic crystals are recorded 0.6 and 18 tera-watt cmâ2 by reducing several undesirable nonlinear optical effects using mid-infrared source
A New Perspective for Dipolarization Front Dynamics: Electromagnetic Effects of Velocity Inhomogeneity
The stability of a quasiâstatic nearâEarth dipolarization front (DF) is investigated with a twoâdimensional electromagnetic particleâinâcell model. Strongly localized ambipolar electric fields selfâconsistently generate a highly sheared dawnward EâĂBâ electron drift on the kinetic scale in the DF. Electromagnetic particleâinâcell simulations based on the observed DF thickness and gradients of plasma/magnetic field parameters reveal that the DF is susceptible to the kinetic electronâion hybrid (EIH) instability driven by the strong velocity inhomogeneity. The excited waves show a broadband spectrum in the lower hybrid (LH) frequency range, which has been often observed at DFs. The wavelength is comparable to the shear scale length, and the growth rate is also in the LH frequency range, which are consistent with the EIH theory. As a result of the LH wave emissions, the velocity shear is relaxed, and the DF is broadened. When the plasma beta increases, the wave mode shifts to longer wavelengths with reduced growth rates and enhanced magnetic fluctuations although the wave power is mostly in the electrostatic regime. This study highlights the role of velocity inhomogeneity in the dynamics of DF which has been long neglected. The EIH instability is suggested to be an important mechanism for the wave emissions and steadyâstate structure at the DF.Key PointsMagnetotail DF contains a substantial velocity shear in the tangential electron driftThe sheared flow is susceptible to the EIH instability and can broaden the DF by emitting broadband LH wavesThe EIH emissions become more electromagnetic as plasma beta increasesPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152027/1/jgra55215_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152027/2/jgra55215.pd
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