Miracle-dz/UniFAR-FTUs huggingface dataset:
Transient response of Reynolds stress transport to spanwise wall oscillation in a turbulent channel flow

Turbulent channel flow at low Reynolds number subjected to spanwise wall oscillation is studied by direct numerical simulation. The Reynolds stress budgets under the influence of the oscillating wall are analyzed in the first two oscillation periods. It is found that the spanwise velocity fluctuations are enhanced at the very beginning of the wall oscillation, and the subsequent global turbulence suppression is caused by the sustained attenuation of the pressure-strain terms. The hindrance of intercomponent transfer of turbulent kinetic energy by the oscillating wall is a mechanism of the skin-friction reduction.
Electrical Properties of n -Type Gallium Arsenide

As part of a general investigation into the properties of gallium arsenide, the Hall coefficient and resistivity of three pure samples have been measured from 300 to 2\ifmmode^\circ\else\textdegree\fi{}K. The highest mobility measured at 300\ifmmode^\circ\else\textdegree\fi{}K was 7200 ${\mathrm{cm}}^{2}$/V-sec increasing to 22 000 ${\mathrm{cm}}^{2}$/V-sec at 72\ifmmode^\circ\else\textdegree\fi{}K, the mobility temperature curve following the theory of Ehrenreich very closely. At helium temperatures impurity conduction was observed with the resistivity $\ensuremath{\rho}\ensuremath{\propto}\mathrm{exp}(\ensuremath{-}\frac{{\ensuremath{\epsilon}}_{1}}{\mathrm{kT}})$ and ${\ensuremath{\epsilon}}_{1}$ varying from 9.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ eV to 5.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ eV. A discussion of these results is given in terms of the theory of Miller and Abrahams and Twose.
M Dwarf catalog of LAMOST general survey data release one

We present a spectroscopic catalog of 93 619 M dwarfs from the first data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) general survey. During sample selection, M giant contamination was eliminated using 2MASS photometry and CaH/TiO molecular indices. For each spectrum, the spectral subtype and values are provided including radial velocity, Hα equivalent width, a series of prominent molecular band indices, and the metal–sensitive parameter ζ, as well as distances and the space motions for high S/N objects. In addition, Hα emission lines are measured to examine the magnetic activity properties of M dwarfs and 7179 active ones are found. In particular, a subsample with significant variation in magnetic activity is revealed through observations from different epochs. Finally, statistical analysis for this sample is performed, including the metallicity classification, the distribution of molecular band indices and their errors.
Block preconditioners for the discrete incompressible Navier–Stokes equations

We examine the convergence characteristics of iterative methods based on a new preconditioning operator for solving the linear systems arising from discretization and linearization of the steady‐state Navier–Stokes equations. For steady‐state problems, we show that the preconditioned problem has an eigenvalue distribution consisting of a tightly clustered set together with a small number of outliers. These characteristics are directly correlated with the convergence properties of iterative solvers, with convergence rates independent of mesh size and only mildly dependent on viscosity. For evolutionary problems, we show that implicit treatment of the time derivatives leads to systems for which convergence is essentially independent of viscosity. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of metallophthalocyanine‐metal contacts: Electrical properties in a large frequency range

The dark electrical properties of metallophthalocyanine‐metal contacts are studied in an extended frequency range (10−3–105 Hz). The measurements show that the standard Schottky model cannot be applied to metallo‐organic semiconductors. Three different contributions to the admittance may be distinguished. Over the very first few angstroms of the semiconductor extends a surface‐charge layer associated with a high capacitive term. The surface‐charge capacitance is only slightly dependent upon superimposed dc voltages. The so‐called space‐charge region extends below the surface‐charge layer over approximately 2000–4000 A. The properties of this space‐charge region are, however, dramatically different from those found in monocrystalline inorganic semiconductors. The corresponding capacity is almost independent of any dc superimposed voltage. At the same time, the resistance of the space‐charge region is highly dependent on externally applied dc voltages. The I‐V relationship seems to indicate a Frenkel–Poole .
JHK colours of ‘ordinary’ galaxies

On presente la photometrie JHK precise pour 19 galaxies elliptiques, 10 lenticulaires, 29 spirales «ordinaires» et une de type Im dans le systeme photometrique SAAO. Les galaxies elliptiques et lenticulaires sont celles qui presentent le plus haut degre d'uniformite de couleur. On n'a pas note de variation significative de la couleur IR avec le rayon
Wavelengths and hyperfine constants in Ga I and Ga II derived by Fourier transform spectroscopy

Hyperfine and isotope structure have been studied in 18 Ga II lines, recorded with Fourier transform spectroscopy. For 12 of the lines the observed patterns could be analysed, yielding magnetic hyperfine structure constants A for eight Ga II levels. Improved wavelengths are given for a number of prominent Ga II lines, including centres of gravity and the individual hyperfine and isotope components of the lines with significant structure. The components of the spin-forbidden transition 4s24p 2P-4s4p2 4P in Ga I have also been analysed and absolute wavelengths and hyperfine constants A are reported.
Resistive instability in the absence of critical levels

Abstract Fearn and Weiglhofer (1992) identified and investigated an instability of the magnetic field B 0 = B 0(s)1 φ that is resistive in character but which is unstable when the condition usually associated with resistive instability k·B 0 = 0 is not satisfied. The instability is not present when the (cylindrical) container boundaries are perfect conductors. Fearn and Weiglhofer tried to determine what other conditions, particularly on the choice of B 0, are required for instability, but they could find no simple condition. Here we adopt a simpler plane-layer model in which the z-direction is normal to the plane, B 0 = B 0(z)1 y, and the rotation vector Ω lies in the x-z plane, making an angle θ with the z-direction. The case θ = π/2, with ω parallel to the boundaries, corresponds most closely to Fearn and Weiglhofer's (1992) cylindrical model, but is a singular case in the magnetostrophic approximation. We show that the instability exists in the plane-layer model, for all values of θ. The simpler geome.
Two-shot point-diffraction interferometer with an unknown phase shift

On the basis of a modified Mach–Zehnder interferometer, this paper proposes a two-shot point-diffraction interferometer (PDI), by which two π-shifted interferograms are created according to the principle of half-wave loss and are simultaneously captured by a single CCD camera. After an arbitrary unknown phase shift is induced, a second and final shot captures these last two patterns. Then a novel algorithm based on statistical principles is developed to extract the actual phase shift and the wavefront phase from four interferograms. The combination of two required shots and a robust algorithm allows the proposed PDI to be implemented efficiently and accurately. Related simulation and experiments are conducted to prove the correctness of the proposed method.
A stochastic model for particle motion in large-eddy simulation

Most of the studies on large-eddy simulation (LES) of particle-laden flows assume that the effect of subgrid scales on the particle motion is negligible. This assumption may break down, particularly when particles have a small time constant and/or the filtered energy is significant. In this work, a stochastic model is proposed for the particle motion in LES while considering the effect of subgrid fluctuations. The model assumes that the fluid particle seen by the heavy particle evolves based on a diffusion stochastic process. For model assessment, both a priori and a posteriori tests are conducted for a particle-laden decaying isotropic turbulence. In the a priori test the filtered velocity field, obtained via filtering the DNS velocities, and in the a posteriori test the LES velocity field, obtained via the dynamic Smagorinsky model, are applied to particles through the stochastic model. The small-particle statistics obtained through the stochastic model very well match those obtained through DNS in the a priori test, once the effects of the initial conditions have decayed. There is also a good agreement with DNS results in the a posteriori test. It is shown that the neglect of subgrid fluctuations is not acceptable for these cases. For large particle time constants, the model needs to be adjusted.
A study of defects in iron-based binary alloys by the Mössbauer and positron annihilation spectroscopies

The room temperature positron annihilation lifetime spectra and 57Fe Mossbauer spectra were measured for pure Fe as well as for iron-based Fe1−xRex, Fe1−xOsx, Fe1−xMox, and Fe1−xCrx solid solutions, where x is in the range between 0.01 and 0.05. The measurements were performed in order to check if the known from the literature, theoretical calculations on the interactions between vacancies and solute atoms in iron can be supported by the experimental data. The vacancies were created during formation and further mechanical processing of the iron systems under consideration so the spectra mentioned above were collected at least twice for each studied sample synthesized in an arc furnace— after cold rolling to the thickness of about 40 μm as well as after subsequent annealing at 1270 K for 2 h. It was found that only in Fe and the Fe-Cr system the isolated vacancies thermally generated at high temperatures are not observed at the room temperature and cold rolling of the materials leads to creation of another.
Stop-bands for periodic metallic rods: Sculptures that can filter the noise

We perform extensive band structure computation for two-dimensional (2D) periodic arrays of rigid stainless steel cylinders in air, with Bloch vector being perpendicular to the cylinders. For cylinders 2.9 cm in diameter and period of 10 cm (i.e., filling fraction f=0.066) there is no acoustic gap for frequencies below 6.4 kHz. However, the density of states reveals prominent minima at 1.7 and 2.4 kHz. These frequencies do agree with those of the first two attenuation maxima observed in the experiment [Nature 378, 241 (1995)] and are indeed related to diffraction from the [100] and [110] planes. Thus, even with idealization, Sempere’s sculpture exhibits pseudogaps—not full gaps. We stress that, for any value of the period, there is no acoustic gap for f⩽30%; magnitude of the gap, for f>30%, is inversely proportional to the period of the system. Moreover, if the filling fraction exceeds 40%, a second gap, higher in frequency, opens up. In addition, we propose the fabrication of a multiperiodic system in ta.
Collisionless magnetic reconnection: Electron processes and transport modeling

Particle-in-cell simulations are used to investigate collisionless magnetic reconnection in thin current sheets, based on the configuration chosen for the Geospace Environment Modeling (GEM) magnetic reconnection challenge [Birn et al., this issue]. The emphasis is on the overall evolution, as well as details of the particle dynamics in the diffusion region. Here electron distributions show clear signatures of nongyrotropy, whereas ion distributions are simpler in structure. The investigations are extended to current sheets of different widths. Here we derive a scaling law for the evolution dependence on current sheet width. Finally, we perform a detailed comparison between a kinetic and Hall-magnetohydrodynamic model of the same system. The comparison shows that although electric fields appear to be quite similar, details of the evolution appear to be considerably different, indicative of the role of further anisotropies in the ion pressures.
Theoretical study of the influence of a metal enclosure on the parameters of a plasma column sustained by a travelling electromagnetic surface wave

In this paper, we have studied the influence of a metal enclosure on the electromagnetic wave characteristics and on the structure of a plasma column sustained by the wave itself. The present work is an extension of a theoretical model of a plasma column produced by a traveling azimuthally-symmetric electromagnetic surface wave (Zhelyazkov, I. and Benova, E., J. Appl. Phys. 66, 1641 (1989)). The axial profiles of the dimensionless electron number density, wave power, wave number, and wave electric field components have been obtained as a function of an additional parameter η - R1/R taking into account the presence of a metal enclosure near the discharge tube (R being the plasma column radius, R1 the metal tube radius). These results are applied to particular experimental setups.
Observation of fs laser-induced heat dissipation in diamond bulk

Dynamics of refractive index variation in diamond crystal during and after its irradiation by fs laser pulses has been investigated by the pump–probe interferometric technique. It is found that, as well as the positive +Δn variation of refractive index determined by the Kerr effect and the negative −Δn resulting from bulk ionization, there is a positive +Δn determined by material heating. Analysis of experimental data and modeling allows us to visualize a laser heated volume, to trace its growth in time and to determine the temperature of material in the beam waist. The maximum observed temperature for intensity ≈3 × 1012 W cm−2 is estimated as 700 K.
Antecedents impact on brand loyalty in cosmetics industry

This study aimed to examine antecedents’ impact on brand loyalty in a highly competitive of cosmetics industry dealing with a mass majority of younger consumers. The study also addressed the relationship between perceived value and customer satisfaction on the effect of brand loyalty. Women or men purchasing and personally using cosmetic products were participants of this study. Data gathered from a total sample of 200 women or men from multiple ethnicities such as Malayans, Chinese and Indians were used for the statistical analysis. It was collected from main shopping mall centers in Klang Valley. Multiple regression analysis was applied to test relationship between brand loyalty, perceived value and customer satisfaction. Besides that, it tested perceived value, corporate image and service quality and customer satisfaction relationships. The results demonstrated that the perceived value and customer satisfaction had significant influence on brand loyalty; particularly, overall customer satisfaction did influence loyalty intention. As a matter of fact, by maintaining and strengthening its images and values, brand would be positively positioned in the minds of consumers.
Kink instability of flux ropes anchored at one end and free at the other

The kink instability of a magnetized plasma column (flux rope) is a fundamental process observed in laboratory and in natural plasmas. Previous theoretical, experimental, and observational work has focused either on the case of periodic (infinite) ropes (relevant to toroidal systems) or on finite ropes with both ends tied to a specified boundary (relevant to coronal ropes tied at the photosphere). However, in the Sun's corona and in astrophysical systems there is an abundant presence of finite flux ropes tied at one end but free at the other. Motivated by recent experiments conducted on the RSX device (Furno et al., 2006) and by recent theoretical work (Ryutov et al., 2006), the present paper investigates by simulation the linear and nonlinear evolution of free-ended flux ropes. The approach is based on comparing the classic case of a periodic flux rope with the case of a rope tied at one end and free at the other. In the linear phase, periodic and free ropes behave radically differently. A simulation analysis of the linear phase confirms the experimental and phenomenological findings relative to an increased instability of a free rope: the new stability limit is shown to be just half of the classic limit for periodic ropes. In the nonlinear phase, reconnection is observed to be a fundamental enabler to reach the eventual steady state. The mechanism for saturation of a flux rope is investigated and compared with the classic theory (the so-called bubble state model) by Rosenbluth et al. (1976). A remarkable agreement is found for the classic periodic case. The case of a free rope is again very different. The saturated state is observed to present a outwardly spiraling configuration with the displacement of the plasma column increasing progressively and monotonically from the tied end to the free end. The maximum displacement is observed at the free end where it is consistent with the displacement observed in a periodic rope. The key distinction is that in a periodic rope the same displacement is observed throughout the whole rope to form a helix with constant radius.
M‐I coupling scales and energy dumping

The paper reviews three magnetosphere‐ionosphere coupling scales characterizing (1) inverted‐V auroral arcs, (2) so‐called Alfvénic arcs, and (3) dense plasma clouds artificially injected into the magnetosphere. The three scale‐breaking processes are different but follow all from the principle of perfect matching of the wave impedance of the energy and momentum carrier with the effective resistance of the energy dump. As a consequence, wave reflections from the ionosphere are absent or present only in a short initial phase and lead to quasi‐stationary wave fields. In inverted‐V auroral arcs the energy conversion occurs in the low magnetosphere by postacceleration of the current‐carrying hot electrons. For the Alfvénic arc the energy is transferred first to dispersive Alfvén waves which are then damped in the topside ionosphere by accelerating electrons along B and ions transversely to B. Barium plasma clouds break into narrow striations mapping to ionospheric scales that experience a strongly reduced Pedersen conductivity and thus achieve the perfect matching. It is also argued that the scale ΣP/K , derived from electrostatic mapping, is not suited to describe M‐I coupling.
Polarization multistability and instability in a nonlinear dispersive ring cavity

We study the role of polarization in modulational instabilities in a synchronously pumped ring resonator that is filled with an isotropic nonlinear dispersive medium. To describe nonlinear propagation of the polarized field through the ring, we introduce two coupled driven and damped nonlinear Schrodinger equations. These equations, which result from averaging propagation and boundary conditions over each circulation through the ring, permit a simple stability analysis. This analysis predicts polarization multistability in the steady state as well as the emergence of stable pulse trains whose polarization state is either parallel or orthogonal to a linearly polarized synchronous pump beam. The analytical predictions are confirmed and extended by numerical simulations of polarized wave propagation in the cavity.
Australia Telescope Observations of the CTB 33 Complex

We present high-resolution radio continuum, H I absorption, and H90α recombination line observations of the CTB 33 complex and nearby sources (l = 337°, b = 0°) taken with the Australia Telescope Compact Array. We estimate distances to several discrete sources on the basis of H I absorption spectra. Radio recombination lines are detected for two sources in the field. The compact source G337.0-0.1 in the CTB 33 complex, whose nature was previously in doubt, is identified as a supernova remnant with a diameter of ~5 pc. This classification is based on several contributing features: a nonthermal spectral index (-0.6), a shell structure, and the absence of detectable recombination lines. In addition, a 1720 MHz OH maser is probably associated with G337.0-0.1. We conclude that the CTB 33 region is a supernova remnant-H II complex at a distance of ~11 kpc.
Optimal Sobolev inequalities on complete Riemannian manifolds with Ricci curvature bounded below and positive injectivity radius

The concept of best constants for Sobolev embeddings appeared to be crucial for solving limiting cases of some partial differential equations. A striking example where it has played a major role is given by the very famous Yamabe problem. While the situation is well understood for compact manifolds, things are less clear when dealing with complete manifolds. Aubin proved in '76 that optimal Sobolev inequalities are valid for complete manifolds with bounded sectional curvature and positive injectivity radius. We prove here that the result still holds if the bound on the sectional curvature is replaced by a lower bound on the Ricci curvature (a much weaker assumption). We also get estimates for the remaining constants.
Linear stern waves in finite depth channels

This paper formulates an analytically tractable problem for the wake generated by a long flat bottom ship by considering the steady free surface flow of an inviscid, incompressible fluid emerging from beneath a semi-infinite rigid plate. The flow is considered to be irrotational and two-dimensional so that classical potential flow methods can be exploited. In addition, it is assumed that the draft of the plate is small compared to the depth of the channel. The linearized problem is solved exactly using a Fourier transform and the Wiener-Hopf technique, and it is shown that there is a family of subcritical solutions characterized by a train of sinusoidal waves on the downstream free surface. The amplitude of these waves decreases as the Froude number increases. Supercritical solutions are also obtained, but, in general, these have infinite vertical velocities at the trailing edge of the plate. Consideration of further terms in the expansions suggests a way of cancelling the singularity for certain values of the Froude number.
Bifurcations and chaos in a model of a rolling railway wheelset

In this paper we present the results of a numerical investigation of the dynamics of a model of a suspended railway wheelset in the speed range between 0 and 180 km h-1. The wheel rolls on a straight and horizontal track unaffected by external torques. A nonlinear relation between the creepage and the creep forces in the ideal wheel rail contact point is used. The effect of flange contact is modelled by a very stiff spring with a dead band. The suspension elements have linear characteristics, and the wheel profile is assumed to be conical. All other parameters than the speed are kept constant. Both symmetric and asymmetric oscillations and chaotic motion are found. The results are presented as bifurcation diagrams, time series and Poincaré section plots. We apply bifurcation and path following routines to obtain the results. In the last chapter we examine one of the chaotic regions with the help of symbolic dynamics.
A note on inverse function theorems

In this note we use the Newton-Raphson approach to inverse function theorems. We draw natural conclusions when only a left or a right inverse to the differential at a point is available. By using a strengthened version of differential, we are able to use differentiability at a single point as the smoothness condition. Although the method has been used before (cf. [2, p. 167 ff.]), analysis books have tended to use an approach that assumes finite dimensionality of the reference spaces. DEFINITION. Let U and V be Banach spaces and f: U-* V a function. A strong differential of f at a point xO in U is a bounded linear transformation a: U-* V which approximates changes of f in the sense that for every E> 0, there is a 5 >0 such that if x' and x" are nearer than a to 0, then: