Search

The fuel injection system is the main process in supersonic vehicles. In this article, injection of fuel jet through a trapezoidal strut in the coaxial supersonic air stream is investigated. The numerical method is applied for the simulation of three-dimensional trapezoidal lobe strut in supersonic flow. Hydrogen gas is injected from the end of the trapezoidal strut injector to augment fuel mixing and diffusion downstream by intensifying vortices inside the domain. The power of the vortices varies by the injector velocity and free stream condition. To simulate our model, RANS equations with the SST turbulence model are solved. Effects of free-stream velocity and fuel jet total pressure on fuel distribution and mixing are also investigated. Our results indicate that fuel mixing enhances about 18% when a rectangular strut is replaced by a trapezoidal one. An achieved finding disclosed that the strength of vortices is amplified by the presence of a trapezoidal strut injector., Comment: arXiv admin note: This version withdrawn by arXiv administrators because the author did not have the right to agree to our license at the time of submission

Spontaneous avalanche to plasma splits the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion first quenches the electron temperature of this core plasma. Then, long-range, resonant charge transfer from ballistic ions to frozen Rydberg molecules in the wings of the ellipsoid quenches the centre-of-mass ion/Rydberg molecule velocity distribution. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy of initially formed hot electrons and ions drives an observed separation of plasma volumes. These dynamics adiabatically sequester energy in a reservoir of mass transport, starting a process that anneals separating volumes to form an apparent glass of strongly coupled ions and electrons. Short-time electron spectroscopy provides experimental evidence for complete ionization. The long lifetime of this system, particularly its stability with respect to recombination and neutral dissociation, suggests that this transformation affords a robust state of arrested relaxation, far from thermal equilibrium.

In this paper, we study generalized Douglas-Weyl $(\alpha, \beta)$-metrics. Suppose that an regular $(\alpha, \beta)$-metric $F$ is not of Randers type. We prove that $F$ is a generalized Douglas-Weyl metric with vanishing S-curvature if and only if it is a Berwald metric. Moreover by ignoring the regularity, if $F$ is not a Berwald metric then we find a family of almost regular Finsler metrics which is not Douglas nor Weyl. As its application, we show that generalized Douglas-Weyl square metric or Matsumoto metric with isotropic mean Berwald curvature are Berwald metrics., Comment: 10 pages

In this paper, we study one of the open problems in Finsler geometry which presented by Matsumoto-Shimada about the existence of P-reducible metric which is not C-reducible. For this aim, we study a class of Finsler metrics called generalized P-reducible metrics that contains the class of P-reducible metrics. We prove that every generalized P-reducible $(\alpha, \beta)$-metric with vanishing S-curvature reduces to a Berwald metric or C-reducible metric. It results that there is not any concrete P-reducible $(\alpha,\beta)$-metric with vanishing S-curvature., Comment: The main result holds for $(\alpha, \beta)$-Metrics with isotropic S-curvature!

Using density functional theory combined with a Green's function scattering approach, we examine the thermoelectric properties of hetero-nanoribbons formed from alternating lengths of graphene and boron nitride. In such structures, the boron nitride acts as a tunnel barrier, which weakly couples states in the graphene, to form mini-bands . In un-doped nanoribbons, the mini bands are symmetrically positioned relative to the Fermi energy and do not enhance thermoelectric performance significantly. In contrast, when the ribbons are doped by electron donating or electron accepting adsorbates, the thermopower S and electronic figure of merit are enhanced and either positive or negative thermopowers can be obtained. In the most favourable case, doping with the electron donor tetrathiafulvalene (TTF) increases the room-temperature thermopower to -284 {\mu}v/K and doping by the electron acceptor tetracyanoethylene (TCNE) increases S to 210 {\mu}v/K. After including both electron and phonon contributions to the thermal conductance, figures of merit ZT up to of order 0.9 are obtained.

We have developed an efficient simulation tool 'GOLLUM' for the computation of electrical, spin and thermal transport characteristics of complex nanostructures. The new multi-scale, multi-terminal tool addresses a number of new challenges and functionalities that have emerged in nanoscale-scale transport over the past few years. To illustrate the flexibility and functionality of GOLLUM, we present a range of demonstrator calculations encompassing charge, spin and thermal transport, corrections to density functional theory such as LDA+U and spectral adjustments, transport in the presence of non-collinear magnetism, the quantum-Hall effect, Kondo and Coulomb blockade effects, finite-voltage transport, multi-terminal transport, quantum pumps, superconducting nanostructures, environmental effects and pulling curves and conductance histograms for mechanically-controlled-break-junction experiments., Comment: 66 journal pages, 57 figures