439 research outputs found
Meson Excitation at Finite Chemical Potential
We consider a probe stable meson in the holographic quark-gluon plasma at
zero temperature and chemical potential. Due to the energy injection into the
plasma, the temperature and chemical potential are increased to arbitrary
finite values and the meson is also excited. Excitation time tex is the time at
which the meson falls into the final excited state. We study the effect of
various parameters of theory on the excitation time and observe that for larger
values of final temperature and chemical potential the excitation time
increases. Furthermore, our outcomes show that the more stable mesons are
excited sooner.Comment: 10 pages, 9 figures, references added, appendix added, typos
correcte
Meson Life Time in the Anisotropic Quark-Gluon Plasma
In the hot (an)isotropic plasma the meson life time is defined as a
time scale after which the meson dissociates. According to the gauge/gravity
duality, this time can be identified with the inverse of the imaginary part of
the frequency of the quasinormal modes, , in the (an)isotropic black
hole background. In the high temperature limit, we numerically show that at
fixed temperature(entropy density) the life time of the mesons
decreases(increases) as the anisotropy parameter raises. For general case, at
fixed temperature we introduce a polynomial function for and observe
that the meson life time decreases. Moreover, we realize that ,
where and are entropy density and temperature of the plasma
respectively, can be expressed as a function of anisotropy parameter over
temperature. Interestingly, this function is a Pad\'{e} approximant.Comment: 5 pages, 4 figures, 1 tabl
Chiral Magnetic Effect in the Anisotropic Quark-Gluon Plasma
An anisotropic thermal plasma phase of a strongly coupled gauge theory can be
holographically modelled by an anisotropic AdS black hole. The temperature and
anisotropy parameter of the AdS black hole background of interest [1] is
specified by the location of the horizon and the value of the Dilaton field at
the horizon. Interestingly, for the first time, we obtain two functions for the
values of the horizon and Dilaton field in terms of the temperature and
anisotropy parameter. Then by introducing a number of spinning probe D7-branes
in the anisotropic background, we compute the value of the chiral magnetic
effect (CME). We observe that in the isotropic and anisotropic plasma the value
of the CME is equal for the massless quarks. However, at fixed temperature,
raising the anisotropy in the system will increase the value of the CME for the
massive quarks.Comment: 22 pages, 8 figure
Finite element modeling of a wind turbine blade
Wind energy is a sustainable source of power that has a much lower environmental impact than conventional energy sources. One of the important stages in developing the modern wind turbines is studying the dynamic behavior of the flexible blades. In this article, a finite element beam model of a 150 kW horizontal axis wind turbine blade is presented. The beam elements of the present model are linear with 14 DOF and arbitrary cross sections that consider rotational velocity, shear center, warping and gyroscopic effects, stiffening due to the rotation, and all the couplings. In the present model, the cross-sectional properties along each element are variable that decreases number of the needed elements, size of the model and hence the analyses running time. By using the present model, natural frequencies, mode shapes and frequency and transient responses of the blade are extracted. The modal properties are compared with another finite element beam code BModes, and with a shell finite element model of the same blade in ABAQUS. The blade frequency and transient responses in the flap and edge directions under a turbulent wind loading are also compared with ABAQUS. Furthermore, the effects of the rotational speed and pitch angle on the blade modal properties are studied
- …