11,645 research outputs found
Investigation of chemically reacting and radiating supersonic internal flows
The two-dimensional spatially elliptic Navier-Stokes equations are used to investigate the chemically reacting and radiating supersonic flow of the hydrogen-air system between two parallel plates and in a channel with a ten degree compression-expansion ramp at the lower boundary. The explicit unsplit finite-difference technique of MacCormack is used to advance the governing equations in time until convergence is achieved. The chemistry source term in the species equation is treated implicitly to alleviate the stiffness associated with fast reactions. The tangent slab approximation is employed in the radiative flux formation. Both pseudo-gray and nongray models are used to represent the absorption characteristics of the participating species. Results obtained for specific conditions indicate that the radiative interaction can have a significant influence on the flow field
On the categories of L-Valued and Q-Valued 6 deterministic fuzzy automata
Automata and languages have been studied in the context of different lattice structures by several authors. This paper is toward the categorical study of deterministic lattice-valued (L-valued) fuzzy automata and deterministic quantale-valued (Q-valued)
fuzzy automata. The existence of initial and final objects in the subcategory of category of deterministic lattice-valued fuzzy automata is shown. We also show that there is an adjunction between the category of deterministic lattice-valued and quantale-valued
fuzzy automata
Vertical flows and mass flux balance of sunspot umbral dots
A new Stokes inversion technique that greatly reduces the effect of the
spatial point spread function of the telescope is used to constrain the
physical properties of umbral dots (UDs). The depth-dependent inversion of the
Stokes parameters from a sunspot umbra recorded with Hinode SOT/SP revealed
significant temperature enhancements and magnetic field weakenings in the core
of the UDs in deep photospheric layers. Additionally, we found upflows of
around 960 m/s in peripheral UDs (i.e., UDs close to the penumbra) and
600 m/s in central UDs. For the first time, we also detected
systematic downflows for distances larger than 200 km from the UD center that
balance the upflowing mass flux. In the upper photosphere, we found almost no
difference between the UDs and their diffuse umbral background.Comment: Accepted for publication in Astronomy and Astrophysic
Rotating light, OAM paradox and relativistic complex scalar field
Recent studies show that the angular momentum, both spin and orbital, of
rotating light beams possesses counter-intuitive characteristics. We present a
new approach to the question of orbital angular momentum of light based on the
complex massless scalar field representation of light. The covariant equation
for the scalar field is treated in rotating system using the general
relativistic framework. First we show the equivalence of the U(1) gauge current
for the scalar field with the Poynting vector continuity equation for paraxial
light, and then apply the formalism to the calculation of the orbital angular
momentum of rotating light beams. If the difference between the co-, contra-,
and physical quantities is properly accounted for there does not result any
paradox in the orbital angular momentum of rotating light. An artificial
analogue of the paradoxical situation could be constructed but it is wrong
within the present formalism. It is shown that the orbital angular momentum of
rotating beam comprising of modes with opposite azimuthal indices corresponds
to that of rigid rotation. A short review on the electromagnetism in
noninertial systems is presented to motivate a fully covariant Maxwell field
approach in rotating system to address the rotating light phenomenon.Comment: No figure
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