3,972 research outputs found
Reduced-complexity transmit-beamforming codebook search algorithm
A two-stage reduced-complexity index search algorithm is proposed for finding the best vector in the codebook of quantised equal gain transmission based multiple-input multiple-output arrangements. When the number of transmit antennas is more than three, the normalised complexity is halved while maintaining the same symbol error rate as the benchmark
Density of Yang-Lee zeros for the Ising ferromagnet
The densities of Yang-Lee zeros for the Ising ferromagnet on the
square lattice are evaluated from the exact grand partition functions
(). The properties of the density of Yang-Lee zeros are discussed as
a function of temperature and system size . The three different classes
of phase transitions for the Ising ferromagnet, first-order phase transition,
second-order phase transition, and Yang-Lee edge singularity, are clearly
distinguished by estimating the magnetic scaling exponent from the
densities of zeros for finite-size systems. The divergence of the density of
zeros at Yang-Lee edge in high temperatures (Yang-Lee edge singularity), which
has been detected only by the series expansion until now for the square-lattice
Ising ferromagnet, is obtained from the finite-size data. The identification of
the orders of phase transitions in small systems is also discussed using the
density of Yang-Lee zeros.Comment: to appear in Physical Review
Thermal activation energy of 3D vortex matter in NaFe1-xCoxAs (x=0.01, 0.03 and 0.07) single crystals
We report on the thermally activated flux flow dependency on the doping
dependent mixed state in NaFe1-xCoxAs (x=0.01, 0.03, and 0.07) crystals using
the magnetoresistivity in the case of B//c-axis and B//ab-plane. It was found
clearly that irrespective of the doping ratio, magnetoresistivity showed a
distinct tail just above the Tc, offset associated with the thermally activated
flux flow (TAFF) in our crystals. Furthermore, in TAFF region the temperature
dependence of the activation energy follows the relation U(T, B)=U_0 (B)
(1-T/T_c )^q with q=1.5 in all studied crystals. The magnetic field dependence
of the activation energy follows a power law of U_0 (B)~B^(-{\alpha}) where the
exponent {\alpha} is changed from a low value to a high value at a crossover
field of B=~2T, indicating the transition from collective to plastic pinning in
the crystals. Finally, it is suggested that the 3D vortex phase is the dominant
phase in the low-temperature region as compared to the TAFF region in our
series samples
Computational Fluid Dynamics Analysis of the Stall Characteristics of a Wing Designed Based on Prandtl's Mininum Induced Drag
Stall characteristics of a wing designed based on Prandtls minimum induced drag solution using the bending moment as the design constraint is presented. Flow field is resolved using the Reynold-Averaged Navier Stokes solver OVERFLOW, version 2.2l, with fully turbulent flow approximation. The turbulence was resolved using the Spalart-Allmaras turbulence model with rotational and curvature correction. Grid independence study show acceptable grid resolution is achieved. The stall angle-of-attack was predicted at 17.25. CFD analysis show that large separations begins inboard, near the symmetry plane, and exists at stall. However, the separated region remain localized and the flow at the wing tip remain attached
Electronic and phonon excitations in {\alpha}-RuCl
We report on THz, infrared reflectivity and transmission experiments for wave
numbers from 10 to 8000 cm ( 1 meV - 1 eV) and for temperatures
from 5 to 295 K on the Kitaev candidate material {\alpha}-RuCl. As reported
earlier, the compound under investigation passes through a first-order
structural phase transition, from a monoclinic high-temperature to a
rhombohedral low-temperature phase. The phase transition shows an extreme and
unusual hysteretic behavior, which extends from 60 to 166 K. In passing this
phase transition, in the complete frequency range investigated we found a
significant reflectance change, which amounts almost a factor of two. We
provide a broadband spectrum of dielectric constant, dielectric loss and
optical conductivity from the THz to the mid infrared regime and study in
detail the phonon response and the low-lying electronic density of states. We
provide evidence for the onset of an optical energy gap, which is of order 200
meV, in good agreement with the gap derived from measurements of the DC
electrical resistivity. Remarkably, the onset of the gap exhibits a strong blue
shift on increasing temperatures.Comment: 18 pages, 7 figure
K*{\Lambda}(1116) photoproduction and nucleon resonances
In this presentation, we report our recent studies on the
photoproduction off the proton target, using the tree-level Born approximation,
via the effective Lagrangian approach. In addition, we include the nine (three-
or four-star confirmed) nucleon resonances below the threshold
MeV, to interpret the discrepancy between the
experiment and previous theoretical studies, in the vicinity of the threshold
region. From the numerical studies, we observe that the and
play an important role for the cross-section enhancement near
the . It also turns out that, in order to reproduce the
data, we have the vector coupling constants
and
.Comment: 2 pages, 2 figures, talk given at International Conference on the
structure of baryons, BARYONS'10, Dec. 7-11, 2010, Osaka, Japa
Heavy pseudoscalar-meson decay constants with strangeness from the extended nonlocal chiral-quark model
We study the weak-decay constants for the heavy pseudoscalar mesons, D, Ds,
B, and Bs. For this purpose, we employ the extended nonlocal chiral-quark model
(ExNLChQM), motivated by the heavy-quark effective field theory as well as the
instanton-vacuum configuration. In addition to the heavy-quark symmetry and the
nonlocal interactions between quarks and pseudoscalar mesons in ExNLChQM, a
correction for the strange-quark content inside Ds and Bs is also taken into
account and found to be crucial to reproduce the empirical values. From those
numerical results, we obtain f_{D,Ds,B,Bs}=(207.53, 262.56, 208.13, 262.39)
MeV, which are in good agreement with experimental data and other theoretical
estimations. Using those numerical results, we compute the CKM matrix elements
and the Cabibbo angle, using various mesonic and leptonic heavy-meson decay
channels, resulting in
(|V_{cd}|,|V_{cs}|,|V_{ub}|,|V_{td}|/|V_{ts}|)=(0.224,0.968,<5.395*10^{-3},0.215)
and theta_C=12.36^o which are well compatible with available data.Comment: 12 pages, 7 figures, accepted for publication in Mod. Phys. Lett.
An effective thermodynamic potential from the instanton with Polyakov-loop contributions
We derive an effective thermodynamic potential (Omega_eff) at finite
temperature (T>0) and zero quark-chemical potential (mu_R=0), using the
singular-gauge instanton solution and Matsubara formula for N_c=3 and N_f=2 in
the chiral limit. The momentum-dependent constituent-quark mass is also
obtained as a function of T, employing the Harrington-Shepard caloron solution
in the large-N_c limit. In addition, we take into account the imaginary quark
chemical potential mu_I = A_4, translated as the traced Polayakov-loop (Phi) as
an order parameter for the Z(N_c) symmsetry, characterizing the confinement
(intact) and deconfinement (spontaneously broken) phases. As a result, we
observe the crossover of the chiral (chi) order parameter sigma^2 and Phi. It
also turns out that the critical temperature for the deconfinment phase
transition, T^Z_c is lowered by about (5-10)% in comparison to the case with a
constant constituent-quark mass. This behavior can be understood by
considerable effects from the partial chiral restoration and nontrivial QCD
vacuum on Phi. Numerical calculations show that the crossover transitions occur
at (T^chi_c,T^Z_c) ~ (216,227) MeV.Comment: 15 pages, 7 figure
Impact of BovineSomatotropin (BST) on Dairy Produce
The use of bovine somatotropin (BST) in dairy herds has been shown to increase productivity levels. Bovine somatotropin is a biotechnology that, when injected in dairy cows, results in increased milk production levels anywhere from 10 to 40 percent (Kalter, et al.). Presently the injections are daily and have been shown to have a rather quick and dramatic increase in production levels
- …