38 research outputs found
Model-based manoeuvre analysis: a path to a new paradigm in aircraft flight dynamics
We propose a closed-form system of nonlinear equations for the pitch plane or longitudinal motions of a fixed-wing aircraft and use it to demonstrate a possible path to the unification of theoretical flight dynamics and practical analysis of aircraft manoeuvres. The derivation of an explicit model free of data tables and interpolated functions is enabled by our use of empirical formulae for lift and drag which agree with experiments. We validate the model by recovering the well-known short period and phugoid modes, and the regions of normal and reversed command. We then use the model to present detailed simulations of two acrobatic manoeuvres, an Immelmann turn and a vertical dive. Providing new quantitative insights into the dynamics of aviation, our model-based manoeuvre analysis has the potential to impact both the academic flight dynamics curriculum and the ground training program for pilots of manned and unmanned aircraft. Possible consequences of future model-centric pilot training may include improved safety standards in general and commercial aviation as well as expedited theoretical course completion in air transport
Voros product and the Pauli principle at low energies
Using the Voros star product, we investigate the status of the two particle
correlation function to study the possible extent to which the previously
proposed violation of the Pauli principle may impact at low energies. The
results show interesting features which are not present in the computations
made using the Moyal star product.Comment: 5 pages LateX, minor correction
Analytic study of Gauss-Bonnet holographic superconductors in Born-Infeld electrodynamics
Using Sturm-Liouville (SL) eigenvalue problem, we investigate several
properties of holographic s-wave superconductors in Gauss-Bonnet gravity with
Born-Infeld electrodynamics in the probe limit. Our analytic scheme has been
found to be in good agreement with the numerical results. From our analysis it
is quite evident that the scalar hair formation at low temperatures is indeed
affected by both the Gauss-Bonnet as well as the Born-Infeld coupling
parameters. We also compute the critical exponent associated with the
condensation near the critical temperature. The value of the critical exponent
thus obtained indeed suggests a universal mean field behavior.Comment: 9 pages, Latex, minor modifications, To appear in JHE
Analytic study of properties of holographic p-wave superconductors
In this paper, we analytically investigate the properties of p-wave
holographic superconductors in -Schwarzschild background by two
approaches, one based on the Sturm-Liouville eigenvalue problem and the other
based on the matching of the solutions to the field equations near the horizon
and near the asymptotic region. The relation between the critical
temperature and the charge density has been obtained and the dependence of the
expectation value of the condensation operator on the temperature has been
found. Our results are in very good agreement with the existing numerical
results. The critical exponent of the condensation also comes out to be 1/2
which is the universal value in the mean field theory.Comment: Latex, To appear in JHE
String non(anti)commutativity for Neveu-Schwarz boundary conditions
The appearance of non(anti)commutativity in superstring theory, satisfying
the Neveu-Schwarz boundary conditions is discussed in this paper. Both an open
free superstring and also one moving in a background antisymmetric tensor field
are analyzed to illustrate the point that string non(anti)commutativity is a
consequence of the nontrivial boundary conditions. The method used here is
quite different from several other approaches where boundary conditions were
treated as constraints. An interesting observation of this study is that, one
requires that the bosonic sector satisfies Dirichlet boundary conditions at one
end and Neumann at the other in the case of the bosonic variables
being antiperiodic. The non(anti)commutative structures derived in this paper
also leads to the closure of the super constraint algebra which is essential
for the internal consistency of our analysis.Comment: new references added, original article appeared in Int.J.Theor.Phy
Influence of reaction time and synthesis temperature on the physical properties of ZnO nanoparticles synthesized by the hydrothermal method
Influence of synthesis temperature and reaction time on the structural and optical properties of ZnO nanoparticles synthesized by the hydrothermal method was investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray, Fourier transform infra-red spectroscopy, and UV–visible and fluorescence spectroscopy. The XRD pattern and HR-TEM images confirmed the presence of crystalline hexagonal wurtzite ZnO nanoparticles with average crystallite size in the range 30–40 nm. Their energy gap determined by fluorescence was found to depend on the synthesis temperature and reaction time with values in the range 2.90–3.78 eV. Thermal analysis, thermogravimetric and the differential scanning calorimetry were used to study the thermal reactions and weight loss with heat of the prepared ZnO nanoparticles
Analytic study of properties of holographic superconductors in Born-Infeld electrodynamics
In this paper, based on the Sturm-Liouville eigenvalue problem, we
analytically investigate several properties of holographic s-wave
superconductors in the background of a Schwarzschild-AdS spacetime in the
framework of Born-Infeld electrodynamics. Based on a perturbative approach, we
explicitly find the relation between the critical temperature and the charge
density and also the fact that the Born-Infeld coupling parameter indeed
affects the formation of scalar hair at low temperatures. Higher value of the
Born-Infeld parameter results in a harder condensation to form. We further
compute the critical exponent associated with the condensation near the
critical temperature. The analytical results obtained are found to be in good
agreement with the existing numerical results.Comment: 12 pages, LateX, To appear in JHE