Miracle-dz/UniFAR-FTUs huggingface dataset:
Nonlinear evolution, travelling waves, and secondary instability of sheared-film flows with insoluble surfactants

The nonlinear development of the interfacial-surfactant instability is studied for the semi-infinite plane Couette film flow. Disturbances whose spatial period is close to the marginal wavelength of the long-wave instability are considered first. Appropriate weakly nonlinear partial differential equations (PDEs) which couple the disturbances of the film thickness and the surfactant concentration are obtained from the strongly nonlinear lubrication-approximation PDEs. In a rescaled form each of the two systems of PDEs is controlled by a single parameter C, the ‘shear-Marangoni number’. From the weakly nonlinear PDEs, a single Stuart–Landau ordinary differential equation (ODE) for an amplitude describing the unstable fundamental mode is derived. By comparing the solutions of the Stuart–Landau equation with numerical simulations of the underlying weakly and strongly nonlinear PDEs, it is verified that the Stuart–Landau equation closely approximates the small-amplitude saturation to travelling waves, and that the error of the approximation converges to zero at the marginal stability curve. In contrast to all previous stability work on flows that combine interfacial shear and surfactant, some analytical nonlinear results are obtained. The Hopf bifurcation to travelling waves is supercritical for C < Cs and subcritical for C > Cs, where Cs is approximately 0.29. This is confirmed with a numerical continuation and bifurcation technique for ODEs. For the subcritical cases, there are two values of equilibrium amplitude for a range of C near Cs, but the travelling wave with the smaller amplitude is unstable as a periodic orbit of the associated dynamical system (whose independent variable is the spatial coordinate). By using the Bloch (‘Floquet’) disturbance modes in the linearized PDEs, it transpires that all the small-amplitude travelling-wave equilibria are unstable to sufficiently long-wave disturbances. This theoretical result is confirmed by numerical simulations which invariably show the large-amplitude saturation of the disturbances. In view of this secondary instability, the existence of small-amplitude periodic solutions (on the real line) bifurcating from the uniform flow at the marginal values of the shear-Marangoni number does not contradict the earlier conclusions that the interfacial-surfactant instability has a strongly nonlinear character, in the sense that there are no small-amplitude attractors such that the entire evolution towards them is captured by weakly-nonlinear equations. This suggests that, in general, for flowing-film instabilities that have zero wavenumber at criticality, the saturated disturbance amplitudes do not always have to decrease to zero as the control parameter approaches its value at criticality.
Elastic photoelectron scattering effects in the XPS analysis of stratified samples

Two theoretical models describing photoelectron transport in multilayer samples were developed: (i) the Monte Carlo simulation strategy, in which the photoelectron elastic scattering events are accounted for, and (ii) the common x-ray electron spectroscopy (XPS) formalism adjusted to multilayer systems, in which the photoelectron elastic scattering events are ignored. Calculations were performed for Au/Ni and Si/Au multilayer systems with layers of different thicknesses. The emission depth distribution function (EMDDF) calculated for a layer deposited at a surface turns out to be identical to that for the bulk of the layer material; however, it may differ considerably when the layer is buried at a certain depth. The EMDDFs for buried layers are found to be considerably affected by elastic photoelectron scattering, however, in a different way from the EMDDF of the bulk material. The XPS depth profiles calculated for multilayer materials in the considered geometry are noticeably affected by elastic photoelectron collisions. However, in contrast with Auger electron spectroscopy depth profiling, the shape of the profile due to a given layer is not affected by the structure beneath that layer.
Influence of latent period and nonlinearincidence rate on the dynamics of SIRS epidemiological models

A disease transmission model of SIRS type with latent period and nonlinear incidence rate is considered. Latent period is assumed to be a constant $\tau$, and the incidence rate is assumed to be of a specific nonlinear form, namely, $\frac{kI(t-\tau)S(t)}{1+\alpha I^{h}(t-\tau)}$, where $h\ge 1$. Stability of the disease-free equilibrium, and existence, uniqueness and stability of an endemic equilibrium for the model, are investigated. It is shown that, there exists the basic reproduction number $R_0$ which is independent of the form of the nonlinear incidence rate, if $R_0\le 1$, then the disease-free equilibrium is globally asymptotically stable, whereas if $R_0>1$, then the unique endemic equilibrium is globally asymptotically stable in the interior of the feasible region for the model in which there is no latency, and periodic solutions can arise by Hopf bifurcation from the endemic equilibrium for the model at a critical latency. Some numerical simulations are provided to support our analytical conclusions.
Effect of cataracts on scattering of light in the eye

We compare the radial profiles of light pattern distributions formed in the retina and the exit pupil of a computational model eye, when the wavelength is varying. The computational eye simulates the presence of cataracts, as a particle distribution in the lens. We use three different wavelengths (400, 550 and 700 nm) for the incident light. The results show that for the shorter wavelength the effect of scattering is bigger around the center of the images while for the longest wavelength the light distribution is larger in the edges of the images. The distance from the center of the scattered light pattern to the zone where the profiles cross is inversely proportional to the size of the particles.
Fabricating subwavelength array structures using a near-field photolithographic method

This work presents a photolithographic approach for producing high aspect ratio arrays in photoresist. The photomask is composed of hexagonal/square rod arrays with a thickness of 0. 2μm and a period of 600nm. Illuminating the photomask with a blue laser generates periodically focused beams up to 1μm long and less than 300nm wide. A hexagonal rod array provides a better focused beam than a square array due to its higher symmetry. Finite-difference time-domain calculations elucidate the existence of long focused beams above the photomask. Optical near-field measurements verified those subwavelength beams originating from the rod regions.
Exact Inference in the Inequality Constrained Normal Linear Regression Model

Inference in the inequality constrained normal linear regression model is approached as a problem in Bayesian inference, using a prior that is the product of a conventional uninformative distribution and an indicator function representing the inequality constraints. The posterior distribution is calculated using Monte Carlo numerical integration, which leads directly to the evaluation of expected values of functions of interest. This approach is compared with others that have been proposed. Three empirical examples illustrate the utility of the proposed methods using an inexpensive 32-bit microcomputer.
Modified k – ω Model for Simulation of Cavitating Flows

Although cavitating flows are generally turbulent, the interaction of turbulence and cavitation dynamics is still not well understood. In general, two‐equation models are employed, which were originally developed for single‐phase flows. Therefore they fail by handling cavitation based flow phenomena with very high density variations (dependent on operating condition up to 40000:1). This sudden change of the density causes strong pressure gradients, secondary flows and local compressibility. The aim of this study is to enhance the Wilcox's k‐? model with empirical correlations in order to simulate turbulent cavitating flows more precisely and effciently.
Current collapse and the role of carbon in AlGaN/GaN high electron mobility transistors grown by metalorganic vapor-phase epitaxy

The two deep traps responsible for current collapse in AlGaN/GaN high electron mobility transistors grown by metalorganic vapor-phase epitaxy have been studied by photoionization spectroscopy. Varying the growth pressure of the high resistivity GaN buffer layer results in a change in the deep trap incorporation that is reflected in the observed current collapse. Variations in the measured trap concentrations with growth pressure and carbon incorporation indicate that the deepest trap is a carbon-related defect, while the mid-gap trap may be associated with grain boundaries or dislocations.
Xe–Ne–HCl excimer lamp excited by a phototriggered discharge

We have used a one-dimensional model of the cathode sheath with an external circuit coupled to a kinetics model of the plasma. With a very high potential and a very high pressure, multiplication of the initial electrons due to ionization during their transits towards the anode causes much positive space charge which distorts the distribution of the electric field. The ions thus created in the volume by the initial electrons turn towards the cathode, causing the emission of secondary electrons and consequently producing more avalanches. Breakdown is primarily due to successive avalanches of the electrons of the cathode which are propagated in the sheath with a high field. Plasma is thus formed; ionization is mainly due to the electron impact but is also due to accumulation of the metastable species in the gap. The growth of the excited-state Xe* is caused by the electron impact of the xenon atoms and NeXe+ ions.
CCD Photometry of the MUSES-C Mission Target: Asteroid (25143) 1998 SF36

Near-Earth asteroid (25143) 1998 SF36 is now planned as the target for the Japanese MUSES-C sample return mission. We conducted extensive photometric observations at NAO-Mitaka from 2001 February 15 until March 19 to obtain its physical properties, such as asteroid’s colors, rotation period, phase curve, and light curves. The colors of this asteroid were found to be S-type and in agreement with the spectroscopic result by Binzel et al. (2001, Meteor. Planet. Sci., 36, 1167). From the phase curve of this object, the visual absolute magnitude is obtained to be 18.61 ± 0.18; we suggest that the albedo may be higher than that for typical S-type asteroids, after applying a known empirical relation between phase curve slope and geometric albedo. We also reveal that the synodic rotation period of this asteroid is 12.13 ±0.02hr and the peak-to-peak light variation amplitude at zero phase angle has been shown to be ∼ 0.49mag, which implies the ratio of the longest and intermediate ellipsoidal axes for the asteroid 1.6.
Low‐resistivity ZnCdS films for use as windows in heterojunction solar cells

Low‐resistivity ZnxCd1−xS films have been obtained by a multisource evaporation method. The films have been doped with In during the deposition. The resistivity of such films varies from 2×10−3 Ω cm for x=0 up to 2 Ω cm for x=0.3 and rises up to 1012 Ω cm for x=1. For energies lower than the energy gap, the transparency of these films, when corrected for the reflection loss, can reach a value of almost 100%. In the range of an x variation between 0 and 0.4 these films, because of their low resistivity and their high transparency, can be used as windows in heterojunction solar cells.
Preliminary Test Estimators Induced by Three Large Sample Tests for Stochastic Constraints in a Regression Model with Multivariate Student-t Error

In this article, we consider the preliminary test approach to the estimation of the regression parameter in a multiple regression model with multivariate Student-t distribution. The preliminary test estimators (PTE) based on the Wald (W), Likelihood Ratio (LR), and Lagrangian Multiplier (LM) tests are given under the suspicion of stochastic constraints occurring. The bias, mean square error matr ix (MSEM), and weighted mean square error (WMSE) of the proposed estimators are derived and compared. The conditions of superiority of the proposed estimators are obtained. Finally, we conclude that the optimum choice of the level of significance becomes the traditional choice by using the W test.
Grüneisen numbers in hexagonal crystals

Gruneisen numbers, which relate the change in the phonon mode frequency to the applied strain, can be estimated if all the second‐order and third‐order elastic moduli are known. Expressions for Gruneisen numbers are normally found in the literature for cubic and trigonal crystals only. In the present work, for the first time, expressions for Gruneisen numbers for both longitudinal and shear wave propagation along the (0 0 0 1) axis in hexagonal materials have been derived, considering 41 modes of pure elastic wave propagation affected by a longitudinal strain and 16 pure modes affected by a shear strain. The average of the Gruneisen numbers for longitudinal wave propagation along the hexagonal axis in magnesium is close to the Gruneisen constant determined from the thermal expansivities and specific heat, while the average for shear wave propagation along the c axis is zero, as expected. The expressions derived here can be used to estimate phonon viscosity losses in hexagonal materials.
Finite temperature dense matter studies on next-generation light sources

The construction of short-pulse tunable soft x-ray free electron laser sources based on the self-amplified spontaneous emission process will provide a major advance in capability for dense plasma-related and warm dense matter (WDM) research. The sources will provide 1013 photons in a 200-fs duration pulse that is tunable from approximately 6 to 100 nm. Here we discuss only two of the many applications made possible for WDM that has been severely hampered by the fact that laser-based methods have been unavailable because visible light will not propagate at electron densities of ne≥1022 cm-3. The next-generation light sources will remove these restrictions.
Linear methods for fully relativistic energy-band calculations

The linear augmented plane wave (LAPW) method of Takeda and Kubler (1979) and the augmented spherical wave (ASW) method of Williams and others (1979) are extended to the relativistic case. The relativistic LAPW and ASW methods make use of two eigenfunctions of Dirac's equation with a spherically symmetric effective one-particle potential. In the latter method, furthermore, the total angular momentum representation for the spin-orbit coupling is used in the expansion of wavefunctions describing electronic states. In both methods, the augmentation is applied to both large and small components of wavefunctions in bispinor form. By this method of the augmentation, radial derivatives of radial wavefunctions are made continuous at the muffin-tin sphere surface. Formulae are given for self-consistent relativistic LAPW and ASW methods which can be numerically treated just like the nonrelativistic counterparts.
Jupiter - Structure and composition of the upper atmosphere

The Voyager ultraviolet stellar occultation data yield a temperature of 200 + or - 50 K at about 400 km, and the solar occultation data give 1100 + or - 200 K at 1450 km above the ammonia cloud tops. The temperature gradient between 400 and 1450 km is approximately 1 K/km. The mesospheric temperature structure gives no strong indication of an earth-like mesopause. The heating of the upper atmosphere appears to result from a combination of magnetospheric charged particle precipitation, ion drag, inertia gravity waves, and solar EUV. The volume mixing ratios of CH4 and C2H6 at 325 km are measured to be 2.5(+3, -2) x 10 to the -5th and 2.5(+2.0, -1.5) x 10 to the -6th, respectively, which are lower than in the stratosphere. The C2H2 volume mixing ratio is not greater than 5 x 10 to the -6th at 300 km. The homopause value of the equatorial eddy diffusion coefficient is found to be 1-2 x 10 to the -6th sq cm/s.
Bootstrap confidence cones for directional data

SUMMARY Given a sample from a distribution F supported on a p-dimensional sphere, several confidence cones for the 'mean directional vector' are proposed. Some methods have been available, but they depend on parametric assumptions. In this paper, nonparametric confidence cones based on the bootstrap are considered, and consistency of these methods is obtained under minimal conditions. We compare the performances of bootstrap methods with the others by Monte Carlo simulations.
Temperature dependence of domain-wall depinning fields in constricted Permalloy nanowires

We use ballistic Hall micromagnetometry to determine depinning fields of domain walls (DWs) in Permalloy nanowires in the temperature range between 5 and 50K. The walls are pinned in constrictions defined by a triangularly shaped notch on one side of the wire. The high sensitivity of the Hall sensor to local stray fields allows the detection of individual DWs and a distinction of different wall types. A strong temperature dependence of the depinning fields is observed that can be described by a model with a single energy barrier. For temperatures above 20K, additional types of DWs occur.
Radiation pattern evaluation from near-field intensities on planes

This paper describes, analyzes, and implements an approach to far-field determination from phaseless measurements over two planar surfaces. A proper formulation of the problem is considered as a quadratic inverse one whose data is the square amplitude of the near field. A solution is introduced as the global minimum of an appropriate functional. Next, to perform such a minimization procedure, a finite dimensional representation of the field radiated by sources whose plane-wave spectrum becomes negligible outside a fixed angular domain is used. A detailed investigation of the properties of the mapping connecting the unknowns to the data makes it possible to analyze how to escape from the local minima possibly met in the course of the minimization procedure. To this end, the crucial role of the availability of phaseless data over two different sarfa,ces and of appropriate weights in the functional definition is emphasized, and a reliable iterative procedure converging on the solution, regardless of the starting point, is thus obtained. This property is confirmed by experimental results concerning near-zone data from a shaped reflector at 9 Ghz. It can be readily appreciated that when only the field intensity is detected the complexity and the cost of the equipment required for near-field techniques in antenna testing and diagnostics can be reduced to a very large extent.
Quality measurement of niobium thin films for Nb/Cu superconducting RF cavities

Niobium-coated copper resonator cavities are an interesting alternative to bulk niobium ones for superconducting RF (SCRF) applications to particle accelerators. Magnetron sputtering is the technology developed at CERN for depositing niobium films and applied over the past 20 years. Unfortunately, the observed degradation of the quality factor with increasing cavity voltage, not completely understood, prevents their use in future large accelerators designed to work at gradients higher than 30 MV m−1 with quality factors in the 1010 (or higher) region. At the beginning of the new millennium, new deposition techniques were proposed to overcome the difficulties encountered with magnetron sputtering. This paper presents the main analysis applied to the niobium films to investigate their quality and the obtained results. The correlations between the niobium film properties and the RF performances of accelerating cavities are summarized. The properties of niobium films obtained by magnetron sputtering and by cathodic arc deposition in ultra-high vacuum (UHVCA) are compared. The UHVCA-produced Nb films have structural and transport properties closer to the bulk ones, providing a promising alternative for niobium coated, high voltage, high Q, copper RF cavities with respect to the standard magnetron sputtering technique.
EFFECTS OF AN ACCRETION DISK WIND ON THE PROFILE OF THE BALMER EMISSION LINES FROM ACTIVE GALACTIC NUCLEI

We explore the connection between active galactic nuclei (AGNs) with single- and double-peaked broad Balmer emission lines by using models dealing with radiative transfer effects through a disk wind. Our primary goal is to assess the applicability of the Murray & Chiang model by making an extensive and systematic comparison of the model predictions with data. In the process, we also verify the original derivation and evaluate the importance of general relativistic effects. As the optical depth through the emission layer increases, the peaks of a double-peaked profile move closer and eventually merge, producing a single peak. The properties of the emission line profile depend as sensitively on the geometric parameters of the line-emitting portion of the disk as they do on the disk-wind parameters. Using a parameter range that encompasses the expected characteristics of the broad-line regions in AGNs, we construct a database of model profiles and measure a set of diagnostic properties. Comparisons of the model profiles with emission lines from a subset of Sloan digital Sky Survey quasars show that observed lines are consistent with moderately large optical depth in the disk wind and a range of disk inclinations i ≲ 45°. Including relativistic effects is necessary to produce the asymmetries of observed line profiles.
Allgemeine Theorie der kettenbruchähnlichen Algorithmen, in welchen jede Zahl aus drei vorhergehenden gebildet wird.

so kann man durch successive Substitutionen sowohl αί+3, αί+2, αί+1 durch α^ αΐ9 α2 als auch umgekehrt α^ α19 «2 durch αί+1, α<+2, α<+3 ausdr cken. Bei diesen successiven Substitutionen, in denen man immer jede der allgemeinen Grossen ak entweder durch die vorhergehenden oder durch die folgenden ausdr ckt, hat man niemals eine Division auszuf hren, weil in der Gleichung, welche zur Elimination einer Grosse angewandt wird, diese Grosse immer den Coefficienten l hat. Setzt man daher
The diffusion of contaminant through an accretion disc

The manner in which a trace contaminant diffuses through an accretion disk is calculated. For a steady disk in which the ratio of diffusivity to viscosity, zeta, is taken to be constant through the disk and for which the surface density distribution is taken to be a power law, analytic solutions to the time-dependent equations governing contaminant evolution are presented. The amount of contaminant which can diffuse its way outwards against the bulk inward accretion flow is calculated, and it is shown that this is a sensitive function of a and zeta.
The moissanite anvil cell: a new tool for high-pressure research

Use of high-quality single-crystal moissanite as anvils has made possible a versatile high-pressure apparatus complementary to the diamond anvil cell (DAC) for high-pressure studies to at least the half-megabar pressure range. High-pressure research has been revolutionized by the DACs as a result of the great strength and transparency of diamond. However, the technique often suffers from interference by the diamond spectra and is limited by small anvil sizes. Other gem anvils, such as sapphire and cubic zirconia, have not been able to reach beyond 26 GPa. With gem-quality synthetic moissanite as anvils, we pressurized samples to close to 60 GPa. Moissanite anvils can be made two to three orders of magnitude larger than conventional diamonds, thus providing new opportunities for studies of material properties at high pressures with analytical techniques that are limited to small samples.