Miracle-dz/UniFAR-FTUs huggingface dataset:
Generalized kinetic description of a plasma in an arbitrary field‐aligned potential energy structure

We present a general solution to the collisionless Boltzmann (Vlasov) equation for a free-flowing plasma along a magnetic field line using Liouville's theorem, allowing for an arbitrary field-aligned potential energy structure including nonmonotonicities. The constraints of the existing collisionless kinetic transport models are explored, and the need for a more general approach to the problem of self-consistent potential energy calculations is described. Then a technique that handles an arbitrary potential energy distribution along the field line is presented and discussed. For precipitation of magnetospherically trapped hot plasma, this model yields moment calculations that vary by up to a factor of 2 for various potential energy structures with the same total potential energy drop. The differences are much greater for the high-latitude outflow scenario, giving order of magnitude variations depending on the shape of the potential energy distribution. Self-consistent calculations for the photoelectron-driven polar wind are compared with previous results, and it is shown that even a photoelectron concentration of 0.03% at the base of the simulation (500 km) will cause the potential energy distribution to violate the constraints of the existing models.
Uniqueness of 2-D compressible vortex sheets

We consider compressible vortex sheets for the isentropic Euler equations of gas dynamics in two space dimensions. Under a supersonic condition that precludes violent instabilities, in previous papers [3, 4] we have studied the linearized stability and proved the local existence of piecewise smooth solutions to the nonlinear problem. This is a free boundary nonlinear hyperbolic problem with two main difficulties: the free boundary is characteristic, and the so-called Lopatinskii condition holds only in a weak sense, which yields losses of derivatives. In the present paper we prove that sufficiently smooth solutions are unique.
Electrical Properties of n‐Type Silicon Doped with Gold

Gold was diffused into arsenic‐doped silicon slices with initial resistivity of 0.3 or 5 Ω·cm at temperatures between 850° and 1250°C for times sufficiently long that the gold concentration was essentially constant, except for a very thin surface region which had a much larger concentration. The gold concentration was determined by means of neutron activation analysis. It was found that the gold concentrations were lower than would be expected from published solubility data when diffusion occurred at temperatures below 1100°C. Several surface treatments were found to result in similar gold concentrations when an evaporated gold film was used as the source. The measured room‐temperature resistivity was found to be in fair agreement with computations using accepted values for the various silicon parameters and the gold energy levels. Although refinements in the calculations and improved experimental techniques are both still necessary, it has been shown that the qualitative features of the model on which th.
DELTA A AND STROMGREN PHOTOMETRY OF STARS IN THE RENSON-CATALOGUE OF AP AND AM STARS

We have observed 131 stars of of Renson's (1991) catalogue of Ap and Am stars both in the Stromgren & Maitzen's (1976) system as a contribution to the photometric studies of the broad band flux depression feature in chemically peculiar stars. With few exceptions the probability grouping of Renson for membership in the CP2 group of peculiar stars is nicely reflected by peculiar values of . Comparison with already available values yields slightly larger values due to a minor shift in the filter g 1 sampling the depression. As found by Maitzen & Vogt (1983) the Geneva system peculiarity parameters correlate well with . This study demonstrates the advantageous performance of a photoelectric photometer with a rapidly rotating filter wheel moving in a stop and go mode.
Modified Diffusion Model of Pseudo-Shock Waves Considering Upstream Boundary Layers

Up to the present, two flow models for pseudo-shock waves have been presented, i.e. shockless model and diffusion model. However, since the effects of upstream boundary layer and wall friction in the pseudo-shock region are not considered in these models, the flow properties calculated by these models are identical with those by the theory of normal shock wave, and they are much different form experimental values. In the present study experiments have been performed to investigate the effects of the upstream boundary layer on the pseudo-shock waves, by varying the Mach number and boundary layer thickness upstream of the pseudo-shock. Based on the results and modifying the diffusion model, a new flow model of the pseudo-shock has been presented in which both effects of the upstream boundary layer and the wall friction are taken into account. Calculated values by this modified diffusion model agree better with the experimental values than the previous flow models.
Molecular design of hole transport materials for obtaining high durability in organic electroluminescent diodes

The molecular design of hole transport materials (HTMs) for producing high durability in organic layered electroluminescent (EL) diodes was elucidated. The durability tests were examined using fourteen hole transport materials in the cell structure of an anode/hole transport layer (HTL)/emitter layer (EML)/cathode. The ionization potential (Ip) of HTLs was found to be the dominant factor for obtaining high durability in organic EL devices. The formation of the small energy barrier at the interface of a HTL/anode was required for high durability. Moreover, no straightforward relations between melting point, glass transition temperature of the HTMs, and durability of the EL devices were observed. The EL device using the HTM having a low Ip (5.08 eV) showed an especially remarkable stability. In this case, the half‐life period of the initial luminance was beyond 500 h.
Null hypersurfaces and new variables

Following Ashtekar's (1987) recently revised version of the standard canonical theory, the construction of a new variables canonical formalism for Einstein's theory of gravity is investigated when the time parameter has level sets which are null hypersurfaces. The configuration space variables are the components of a tetrad and the self-dual components of a connection. Because a null time parameter is used, the Hamiltonian formalism has second-class constraints as well as the first-class constraints which are associated with the invariance of the theory under diffeomorphisms and local gauge transformations. The first-class constraint algebra is discussed and reality conditions which relate the complex formalism to real general relativity are displayed.
Evolution of short gravity waves on long gravity waves

The evolution of short gravity waves on long gravity waves on the surface of deep water is studied. Both wave trains are assumed to be irrotational, mild in slope, and slowly modulated in space and time, but their scales are so different that the short wavelength is very much less than the long‐wave amplitude. Here, it is shown that the use of Lagrangian instead of the usual Eulerian coordinates is advantageous for yielding analytical results. Linear and nonlinear evolutions of short waves over intermediate and very long distances are discussed.
The neutral hydrogen distribution of NGC 3079

Multiarray VLA H I observations of the radio lobe spiral galaxy NGC 3079 and it companions NGC 3073 and MCG9-17-9 are reported. It is found that the density and velocity distributions in this galaxy can be adequately described, to first order, by simple exponential or Gaussian functions and a Brandt curve, respectively. From residual line profiles, an anomalous redshifted emissions feature centered at a radius of roughly 3.5 kpc on the southern major axis is found. A distinct redshifted absorption component several hundred pc from the nucleus is detected from nuclear absorption profiles. The galaxy is also distinguished by a centrally peaked H I distribution. 55 refs.
Spectroscopic and Photometric Observations of a Five-Magnitude Flare Event on UV CETI

Abstract : Flare stars are late-type emission-line main sequence stars which exhibit random and rapid increases in luminosity. All dwarf M stars thus far observed in the blue-visible and near ultraviolet emit Ca II H and K and Mg II h and k arising from their low to midchromospheres, respectively. However, only those with enhanced chromospheric and transition region densities emit Ha (Distinguishing dMe from dM) as well as a host of other optical and ultraviolet emission lines. There are several classes of stars that exhibit flaring behavior and related phenomena similar to solar magnetic activity. UV Ceti is the classic prototype of the flare star. These flare stars are isolated systems characterized by a wide range of flaring properties that include, for example, the frequency of flaring and the total flare energy.
The Structure and Defect Formation Energy in Tetragonal PbTiO3: Ab Initio Calculation

The first-principles calculation had been adopted to investigate the intrinsic vacancies in bulk PbTiO3. The atomic relaxation and the formation energy of isolated neutral vacancy were studied respectively. And the defect reaction energies of Pb partial Schottky (VPb 2−+VO 2+), Ti partial Schottky (VTi 4−+2VO 2+), and full Schottky (VPb 2−+ VTi 4−+3VO 2+), were obtained. It was found that both the formation energy of vacancy and the defect reaction energy were connected closely with the thermodynamic condition. By comparing the calculated formation energy values, Pb partial Schottky (VPb 2−+VO 2+) was considered to be the dominant defect species in the seven thermodynamic conditions, consistent with the experimental reports.
Extended Galerkin–Eckhaus Method in Nonlinear Thermoconvection

Abstract We propose an extension of the Galerkin–Eckhaus method in order to study thermoconvective instabilities not only in the weakly nonlinear régime, but also farther from the threshold. This extension consists in an appropriate choice of the basis functions used to expand the unknowns and in an increase of the number of amplitude equations taken into account. The rigid-free Rayleigh–Bénard problem with heat-conducting boundaries and the Marangoni–Bénard problem are considered in detail before generalizing to all thermoconvective instabilities. The validity of our approach is proven by comparing its results with a multiple scale method and with a finite element method. A very good agreement between all methods is found in the weakly nonlinear regime. Farther from the threshold, the agreement between our extended Galerkin–Eckhaus method and the finite element approach is also obtained with appropriate basis functions whose choice depends crucially on the value of the Prandtl number and also on the boundary conditions imposed at the top and bottom of the system.
RF Wave Propagation in Bounded Plasma under Divergent and Convergent Magnetic Field Configurations

Radio frequency (RF) wave propagation in a bounded plasma (cylindrical shape with a large diameter of 45 cm) produced by a planar, spiral antenna was investigated under divergent and convergent magnetic field configurations. The measured excited magnetic field amplitude and the phase were examined based on helicon wave characteristics, and were consistent with the computed results using the Transport Analyzing System for tokamaK/Wave analysis by Finite element method (TASK/WF) code. The wave propagation region was broadened (focused) in the radial direction with increasing distance from the antenna under the divergent (convergent) field.
On operators of stochastic differentiation on spaces of regular test and generalized functions of Levy white noise analysis

The operators of stochastic differentiation, which are closely related with the extended Skorohod stochastic integral and with the Hida stochastic derivative, play an important role in the classical (Gaussian) white noise analysis. In particular, these operators can be used in order to study properties of the extended stochastic integral and of solutions of stochastic equations with Wick-type nonlinearities. In this paper we introduce and study bounded and unbounded operators of stochastic differentiation in the Levy white noise analysis. More exactly, we consider these operators on spaces from parametrized regular rigging of the space of square integrable with respect to the measure of a Levy white noise functions, using the Lytvynov's generalization of the chaotic representation property.This gives a possibility to extend to the Levy white noise analysis and to deepen the corresponding results of the classical white noise analysis.
The electron effective mass in heavily doped GaAs

A resolution to the order k6 of the three-level equation of Kane allows the authors to obtain a new expression for the conduction band energy and so new analytical expressions for the electron effective masses in the range of carrier concentration 1016-1019 cm-3. The calculated values of the conduction effective mass as a function of carrier density agree well, for the first time, with experimental values, which were obtained from Shubnikov-de Haas experiments by using a new expression for the oscillation amplitude. In this expression the authors take into account the effect of medium-range potential fluctuations induced by crystal inhomogeneities.
Electron and hole relaxation pathways in semiconductor quantum dots

Femtosecond (fs) broad-band transient absorption (TA) is used to study the intraband relaxation and depopulation dynamics of electron and hole quantized states in CdSe nanocrystals (NC{close_quote}s) with a range of surface properties. Instead of the drastic reduction in the energy relaxation rate expected due to a {open_quotes}phonon bottleneck,{close_quotes} we observe a fast subpicosecond 1P-to-1S electron relaxation, with the rate exceeding that due to phonon emission in bulk semiconductors. The energy relaxation is enhanced with reducing the NC{close_quote}s radius, and does not show any dependence on the NC surface properties (quality of the surface passivation). These data indicate that electron energy relaxation occurs by neither multiphonon emission nor by coupling to surface defects, but is likely meditated by Auger-type electron-hole energy transfer. We use fs infrared TA to probe electron and hole intraband transitions, which allows us to distinguish between electron and hole relaxation pathways leading to the depopulation of NC quantized states. In contrast to the electron relaxation, which is controlled by NC surface passivation, the depopulation of hole quantized states is extremely fast (sub-ps-to-ps time scales) in all types of samples, independent of NC surface treatment (including NC{close_quote}s overcoated with a ZnS layer). Our results indicate that ultrafast holemore » dynamics are not due to trapping at localized surface defects such as a vacancy, but rather arise from relaxation into intrinsic NC states or intrinsically unpassivated interface states. {copyright} {ital 1999} {ital The American Physical Society}« less
High-angle scattering of fast electrons from crystals containing heavy elements: Simulation and experiment

The paper reports on quantitative comparisons of experimental and simulated image intensities in high-angle annular dark-field imaging in scanning transmission electron microscopy of a PbWO4 single crystal. The experimental image intensities are normalized to the incident beam. Provided that the effects of spatial incoherence and multiple thermal diffuse scattering events are taken into account in the simulations, excellent agreement within about 5% is achieved between theory and experiments. The comparisons depend critically on accurate knowledge of the Debye-Waller factors, which were determined by x-ray single-crystal structure refinement, and of the experimental thickness values. The Debye-Waller factors are different for different atomic columns, causing column intensities to not be a simple function of their atomic number. Channeling effects associated with the oxygen columns contribute to intensity variations between the Pb and W columns. The results show that even for single crystals, image simulations are required to correctly interpret the contrast.
The solar flux influence on quiet time conductances in the auroral ionosphere

Hall and Pedersen conductances derived from EISCAT Common Program 1 (CP-1) data during half a solar cycle are presented. The data set consists of 9 quiet summer days with 10.7-cm solar flux (Sa) ranging from solar minimum (Sa=74) to solar maximum (Sa=248) conditions. The solar flux and the solar zenith angle (χ) dependence of Hall (∑H) and Pedersen (∑P) conductances are well represented by respectively. The present results are in good agreement with the theoretical model calculations by Rasmussen et al. [1988] for solar minimum conditions. For higher solar activity levels, however, our model gives consistently higher conductance values than older models.
The Hard X-ray Spectra of the Polars V2301 Oph, BL Hyi, and WW Hor

The hard X-ray spectra of the Polars V2301 Oph and BL Hyi acquired using the Proportional Counting Array (PCA) detector on board the Rossi X-ray Timing Explorer (RXTE) satellite were modeled using theoretical spectra from two-temperature radiative shock models for field-aligned accretion flows onto magnetic white dwarfs. The radiative shock models included the cooling processes e-i and e-e bremsstrahlung and Compton cooling and, importantly, self-consistently included the effects of cyclotron emission through an explicit solution of the radiative transfer equation rather than through the use of the approximate cyclotron cooling function derived by Chanmugam, Langer, and Shaviv. The spectra also included the effects of reflection from the surface of the white dwarf. We also discussed the eclipsing Polar WW Hor within the context of the theoretical shock models. WW Hor was observed and detected by XMM-Newton in the hard X-rays, and, unlike the above named Polars, WW Hor also exhibits an optical light curve with properties characteristic of a shock with cyclotron emission. We find that: (i) based on the X-ray continuum, the mass of the white dwarf in V2301 Oph is M * > ∼ 0.9 - 1 ) M⊙ for the known magnetic field strength B∗ = 7 MG. Using the observed optical flux of V2301 Oph, we set the further upper limit on the white dwarf mass of M∗ ∼ 1.2 M⊙. (ii) Based on the X-ray continuum and the shapes of the B and R optical light curves, we infer that the mass of the white dwarf in WW Hor to M∗ ≳ 0.4 M⊙ with magnetic field B∗ ∼ 15 MG. Using the observed optical flux of WW Hor, we suggest that the lower limit on the mass of the white dwarf mass in WW Hor is M∗ ∼ 0.8 M⊙. We were unable to model the hard X-ray spectrum of BL Hyi using a fitting function composed of an absorbed shock spectrum.
Diffraction by thick conducting half-plane and dielectric-loaded waveguide

Abstract : The paper investigates the problem of diffraction of an incident plane wave by a half-plane with a finite thickness. The generalized scattering matrix procedure, which has been found useful for attacking waveguide discontinuity problems, is shown to apply to open region problems as well. Based on this procedure, a highly convergent Neumann Series solution is derived and numerical calculations are presented for a wide range of parameters. The method of solution is not restricted to sufficiently thin half-planes only as is the one discussed by Jones. Comparisons with Jones' results show good agreement in the range where his results are valid. New results are presented for the extended range of thickness of the half-plane. Two other related problems, viz., those of radiation from a waveguide loaded with a dielectric or plasma medium, and diffraction by an inhomogeneously loaded waveguide, are also investigated in this paper. (Author)
Compressibility effects on the Rayleigh-Taylor instability between miscible fluids

The linear Rayleigh-Taylor problem for two miscible compressible viscous fluids is solved for the first time. A wide range of parameter values is investigated. Two main parameters govern this instability: the stratification parameter —attached to the hydrostatic equilibrium— and the compressibility parameters —attached to the fluids. For increasing values of the stratification, the flow is stabilized, whereas for increasing values of the compressibility parameters the flow is destabilized. Diffusions (viscosity, thermal conduction and species) introduced a cut-off wave number beyond which the flow is marginally stable. These conclusions usually hold in the nonlinear single-mode regime, except when compressibilities are equal. In this case linear and nonlinear growth rates are in opposite order.
The Descent Rates of the Shear Zones of the Equatorial QBO

Abstract The influence of vertical advection on the descent rate of the zero-wind line in both phases of the equatorial quasi-biennial oscillation (QBO) is investigated with the help of the “THIN AIR” stratosphere two-and-a-half-dimensional model. The model QBO is forced by two symmetric easterly and westerly waves, and yet the model reproduces qualitatively the observed asymmetry in the descent rates of the two shear zones due to the enhanced heating during easterly descent combined with the equatorial heating induced by the extratropical planetary waves. Observations show that the maximum easterly accelerations occur predominantly from May until July, which is when the modeled equatorial planetary-wave-induced heating rates are weakest. Hence, model results are consistent with the theory that vertical advection induced by extratropical planetary waves slows significantly the descent of the easterly shear zone. The model also shows the observed increase in vertical wind shear during stalling of the easte.
Characteristics of the Tip Leakage Vortex in a Low-Speed Axial Compressor

The flowfields in the tip region of the rotor passage are investigated from a large-scale low-speed axial compressor test at both the design and near-stall conditions by using stereoscopic particle image velocimetry. The characteristics of the tip leakage vortex (TLV) are analyzed based on the variations of its trajectory, concentration, size, streamwise velocity, and the blockage effect, which are extracted from both the ensemble- and conditional-averaged results. According to the ensemble-averaged performance of the TLV, its evolution procedures can be divided into several distinct flow phases. As the flow phase of the TLV changes, its mean flow characteristics also change accordingly. The TLV is inherently unsteady and features unsteady behaviors of vortex wandering, splitting, and breakdown, which have profound effects to its mean flow characteristics.
Magneto-thermopower and magnetoresistance of single Co-Ni alloy nanowires

The magneto-thermopower is measured and correlated to the anisotropic magnetoresistance of Co-Ni alloyed nanowires with varying composition. The highest absolute and relative variation of the Seebeck coefficient in perpendicularly applied magnetic fields at room temperature is determined to be 1.5 μVK−1 for Co0.24Ni0. 76 and 8.1% for Co0.39Ni0. 61 nanowires. Power factors of 3.7 mW/mK2 have been achieved, which is competitive with common thermoelectric materials like Bi2Te3. For Co-Ni nanowires containing up to 39% Co, a linear relationship between the magnetic field dependent change of the Seebeck coefficient and the electrical conductivity is found.