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Discussion on `Characterization of 1-3 piezoelectric polymer composites - a numerical and analytical evaluation procedure for thickness mode vibrations' by C.V. Madhusudhana Rao, G. Prasad, Condens. Matter Phys., 2010, Vol.13, No.1, 13703
In the paper entitled "Characterization of 1-3 piezoelectric polymer
composites - a numerical and analytical evaluation procedure for thickness mode
vibrations", the dependence of the thickness electromechanical coupling
coefficient on the aspect ratio of piezoceramic fibers is studied by finite
element simulation for various volume fractions of piezoceramic fibers in a 1-3
composite. The accuracy of the results is questionable because the boundary
condition claiming that `predefined displacements are applied perpendicularly
on plane on all nodes' is not suitable for the analysis of 1-3 composite
with comparatively large aspect ratio from 0.2 to 1. A discussion regarding
this problem and the suggested corrections are presented in this paper.Comment: 4 pages, 3 figure
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MHD-RLC discharge model and the efficiency characteristics of plasma synthetic jet actuator
Major factors affecting efficiency of plasma synthetic jet actuator (PSJA) are analyzed based on a new discharge model in the present paper. The model couples the magnetohydrodynamics (MHD) equations with the resistor–inductor–capacitor (RLC) equations, and is able to resolve the time-dependent voltage fall on the sheath region and arc region, which is critical in analyzing energy loss in the heating process. This model is integrated into the commercial CFD software by a two-equation method. Results show that in a typical capacitive discharge at microsecond scale, the maximum energy loss is the sheath energy loss, which accounts for nearly half of the discharge energy, while the radiation loss is less than 5%. The discharge time is an important parameter for the PSJA efficiency. A short discharge time less than 1 μs will effectively reduce the sheath energy loss, while a longer discharge time will decrease the thermodynamic efficiency
Analysis of the strong coupling constant and the decay width of with QCD sum rules
In this article, we calculate the form factors and the coupling constant of
the vertex using the three-point QCD sum rules. We
consider the contributions of the vacuum condensates up to dimension in the
operator product expansion(OPE). And all possible off-shell cases are
considered, , and , resulting in three different form
factors. Then we fit the form factors into analytical functions and extrapolate
them into time-like regions, which giving the coupling constant for the
process. Our analysis indicates that the coupling constant for this vertex is
. The results of this work are very useful
in the other phenomenological analysis. As an application, we calculate the
coupling constant for the decay channel and
analyze the width of this decay with the assumption of the vector meson
dominance of the intermediate . Our final result about the decay
width of this decay channel is .Comment: arXiv admin note: text overlap with arXiv:1501.03088 by other author
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