Miracle-dz/UniFAR-FTUs huggingface dataset:
Influence of reduced mass differences on the Raman spectra of ternary mixed compounds: Zn 1-x Fe x S and Zn 1-x Mn x S

A Raman scattering study of the mixed crystals ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}\mathrm{S}$ and ${\mathrm{Zn}}_{1\ensuremath{-}y}{\mathrm{Mn}}_{y}\mathrm{S}$ has been carried out for different Fe $(0l~xl~0.05)$ and Mn $(0l~yl~0.5)$ concentrations. It is found that both the strengths and the frequencies of the TO and LO modes of ZnS are approximately independent of the Mn (or Fe) concentration. However, as Mn (or Fe) is substituted for Zn, four additional first-order modes with frequencies $\ensuremath{\omega}(\mathrm{TO})l\ensuremath{\omega}l\ensuremath{\omega}(\mathrm{LO})$ are observed in the Raman spectra. Three of the new modes have frequencies equal to those of sharp peaks in the density of states of ZnS and thus they are attributed to resonance or band modes. Another extra mode, with frequency at 323 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, is observed in samples with $xg~0.10,$ and it is assigned to a breathing mode of the nearest-neighbor sulfur atoms around Mn atoms. The observation of such extra features does not correspond to the usual behavior observed in other ternary mixed crystals where either one-, two-, or mixed-mode behavior is observed. Conversely, it is found that the measured frequencies of all the new peaks are nearly constant, independent of the Fe or Mn concentration. This ``frozen-mode'' behavior is believed to occur because of the small reduced mass difference between the binary end members when the Zn atoms are replaced by either Fe or Mn. More specifically it is suggested that the frozen-mode behavior will occur whenever the reduced mass difference between the end pairs (\ensuremath{\Delta}\ensuremath{\mu}) is less than or equal to approximately 2.0 amu. It appears that consideration of the reduced mass difference may also be used to delineate between one- and two-mode behavior. That is, the available data suggest that one-mode behavior occurs in samples with $2\ensuremath{\lesssim}\ensuremath{\Delta}\ensuremath{\mu}\ensuremath{\lesssim}7$ and two-mode behavior in samples with $\ensuremath{\Delta}\ensuremath{\mu}\ensuremath{\gtrsim}7. $
Topside sounder proton‐cyclotron echo generation from a plasma memory process and electron Bernstein‐wave propagation

Evidence is presented for the radiation of an electron Bernstein wave from a radio frequency pulse simulated by proton‐cyclotron motion. The protons are energized by an ionospheric topside sounder transmitter pulse and take part in a plasma memory process that simulates the original transmitter pulse. These echoes appear on topside ionograms as thin traces. At frequencies below the electron cyclotron frequency fH, the proton echo delay is a multiple of the proton‐cyclotron period tp. At frequencies above fH, there can be an additional delay to tp depending on two factors: 1) the antenna orientation and 2) the closeness of the proton echo frequency f to fH. A model is presented here in which protons passing within a few tens of centimeters of the antenna are energized and modulated by the RF pulse by an amount depending on the RF phase. At multiples of tp later, these protons return to almost the same field line they were on at the time of the RF pulse, although they may have moved some tens of meters parallel or antiparallel to the field line. At multiples of tp, ntp, the protons are thus located in a plane defined by the linear dipole antenna (73 m long tip to tip) at the time of the pulse and the direction of the Earth's magnetic field B. At ntp the protons produce a field which simulates the original field of the RF pulse, and, if wave propagation in the plasma is possible, a pulse is produced which propagates to the new position of the antenna which has moved in the plasma at the satellite velocity Vs. For f > fH, the perpendicularly propagating electron Bernstein waves are responsible for the propagation. No such Bernstein waves exist for f < fH, and proton echoes can be observed at these frequencies if Vs is approximately in the plane of the energized protons at ntp so that wave propagation is not necessary to produce a signal that appears as an echo. For the second factor above, as the wave frequency approaches the electron cyclotron frequency, the group velocity of the Bernstein waves approaches zero, and consequently the propagation time to the antenna increases. This change in group velocity explains the observed increase in tp, which can be as much as several percent.
Perception of synthetic speech by children

Many educational and commercial products that produce synthetic speech output are becoming widely available. However, there is little, if any, research on how adults or young children process (i.e., perceive, encode, retrieve) synthetic speech signals. Results of two experiments that studied children's perception of natural and synthetic speech indicated that subjects consistently showed a higher error rate when listening to synthetic speech than natural speech. In one experiment, children 5–8 years old listened to natural and synthetic speech tokens in a task that required them to point to a picture, from among four alternatives, that corresponded to the word heard. In a second experiment, children 8–10 years old listened to natural and synthetic digit strings and repeated the digit strings to the experimenter exactly as heard. Performance deficits were observed for the synthetic speech relative to the natural speech even for highly familiar material such as digits. These results have implications for th.
Limit distributions of maximal segmental score among Markov-dependent partial sums

Let s 1, …, sn be generated governed by an r-state irreducible aperiodic Markov chain. The partial sum process is determined by a realization of states with s0 = α and the real-valued i.i. d. bounded variables Xαß associated with the transitions si = α, si+ 1 = β. Assume Χ αβ has negative stationary mean. The explicit limit distribution of the maximal segmental sum is derived. Computational methods with potential applications to the analysis of random Markov-dependent letter sequences (e.g. DNA and protein sequences) are presented.
Magnetic phase transitions on elastic isotropic lattices

The elimination of the elastic degrees of freedom of a harmonic isotropic lattice transforms the magnetoelastic coupling into an effective magnetic interaction which consists of a short-range interaction recently discussed by Aharony and a long-range interaction due to the free surface of the systems. Within the renormalization group approach to critical phenomena it is shown that the critical behaviour of the system is described appropriately by the magnetothermomechanics provided that the additional short-range interaction does not change the critical behaviour.
The decrease of ‘‘random telegraph signal’’ noise in metal‐oxide‐semiconductor field‐effect transistors when cycled from inversion to accumulation

The low‐frequency (LF) noise behavior of metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) is studied when cycled between inversion and accumulation. On large‐area devices the decrease of the LF noise is systematically found, and supports the observations by Bloom and Nemirovsky [Appl. Phys. Lett. 58, 1664 (1991)]. The random telegraph signal (RTS) noise observed in small (submicrometer) devices disappears when the transistor is cycled into accumulation. The drop in LF noise observed may thus be explained by the fact that most or all of the RTSs, which are caused by carrier trapping into slow oxide states, no longer contribute to the noise of the system. The method indicates a possibility to separate the contributions of different sources of 1/f noise in MOSFETs.
Oscillatory instability in a Bénard problem of two fluids

A linear stability analysis for a Benard problem with two layers is considered. The equations are not self‐adjoint. The system can lose stability to time‐periodic disturbances. For example, it is shown numerically that when the viscosities and coefficients of cubical expansion of the fluids are different, a Hopf bifurcation can occur, resulting in a pair of traveling waves or a standing wave. This may have application in the modeling of convection in the Earth’s mantle.
Large Eddy Simulation of Supersonic Jet Noise from a Circular Nozzle

An imperfectly expanded supersonic jet is simulated with large eddy simulation (LES) method. The full 3D filtered Navier-Stokes equations in cylindrical coordinates coupled with the standard Smagorinsky model are solved by a computational aeroacoustic method. The Dispersion-Relation-Preserving scheme is used for spatial discretization and the low dissipation low dispersion Runge-Kutta method in 2N storage form is utilized for time marching. A high order explicit spatial filter is applied to remove the grid oscillations. An adaptive artificial selective damping is used for shock capturing. The supersonic jet with Mach number 1.19 is simulated. The simultaneous and time average flow field is analyzed. The near filed noise spectra are presented and compared with the experimental data of Ponton et al. and with the numerical results of the present authors by unsteady Reynolds averaged Navier-Stokes (URANS) method. It is shown that the numerical results by LES method agree better with the experimental data than the results by URANS method.
Camouflage assessment considering human perception data

Shape and shape disruption have significant influence to the human target acquisition mechanism. A special testing method (the so called `photo-simulation') was developed in the eighties to present a set of image slides of camouflaged and not camouflaged objects in preferably natural backgrounds to military personnel to quantify differences in object camouflage effectiveness. Statistically significant results were achieved, however, the high test requirements limited its practical use. The project is motivated by an urgent need for a camouflage evaluation system based on computer vision with a fast response so that the user in a field test can be supported to further improve his camouflage skills. Hence, the photo simulation method cannot be regarded as obsolete, it can be used to compare the results of the camouflage evaluation system with the results of human perception. With an human-in-the-loop computer based camouflage assessment system, processing should be sped up by some orders of magnitude, could be automated for field tests and would yield several additional features. To overcome the problem of quantifying e.g. texture similarity of different camouflage nets to blend into the natural background, an image processing/visualization method was pursued by the Austrian Ministry of Defense. Now the same image-sets can be used for the human photo-simulation as well as for segmentation/classification by the camouflage assessment tool. Today a modified Euclid-distance measurement for visual images is being used while similarity of shapes (gestalt) to a selected region can be visualized. Feature selection is being done by training a neural network with the results of the human perception data. A cost effective prototype of a camouflage assessment tool based on standard hardware can be presented. Its promising performance gives hope to get beyond subjective camouflage experts stimuli. In the next project phase also thermal images shall be handled with the camouflage assessment tool.
Theory of capture of particles in magnetic high-intensity filters

This paper considers the capture of paramagnetic particles, of radius R and susceptibility χ from a slurry, of viscosity η, by a ferromagnetic wire, of radius a and saturation magnetization M s , in a uniform magnetic field H o , large enough to saturate the wire, applied perpendicular to the axis of the wire. When the slurry is far away from the wire it's velocity is V o . Capture is considered for various orientations of V o with respect to H o . In the calculations the fluid is treated in the inviscid, incompressible approximation. Calculation shows that when M s /2μ o H o is large, the capture radius R c increases with M s /2μ o H o . For values of M s /2μ o H o m /V o , where V m , is the magnetic velocity, V m = (2χM s H o R2/9ηa). The increased performance observed in magnetic filters when μ o H o m /V o , is consistent with the increase of R c with M s /2μ o H o . Effects observed in filters when various configurations of flow in relation to field are used could not be explained in terms of the differences in the bare wire values of R c . It is argued that these differences are due to different dependences of R c on the volume of material captured in the various configurations.
A simple calculation of energy changes upon stacking fault formation or local crystalline phase transition in semiconductors

We use a simple scheme to calculate the energies of stacking faults, polytypes, and arbitrary stacking sequences in elementary and compound semiconductors. The scheme is based on the calculation of two elementary energies, which can be obtained for each material from the computed difference of energy between its cubic and hexagonal modifications and from the measured or computed energy of a single kind of stacking fault. Formulas are given for faults in both zinc blende and wurtzite structures and for the stacking sequences that occur during the transformation of one phase into the other. This applies in particular to nanowires, where such faults and sequences are frequently encountered.
About the Problem of Existence of a Three-Dimensional Bipolaron

The range of existence of a translation invariant continuum three-dimensional bipolaron in space of two variables: of electron–phonon coupling constant and the dielectric parameters of polar medium is investigated. The critical values of the electron–phonon coupling constant are found. The possibility of existence of metastable bipolaron formations is scored. On the basis of definition of bipolaron existence the requirement of existence of a bound condition in a bipolaron potential well is necessary. It is shown, that use of a rigider requirement, than positivity of dissociation energy, namely presence of even one bound state narrows the range of existence of a bipolaron. The criteria for a bound state to arise are found by solving an integral equation, which corresponds to a Schrodinger equation describing internal states of a bipolaron.
Quantities Of Photobiologically Effective Radiation And Their Measurement

Different groups of quantities are defined for optical radiation, which can be described by a general equation. One of these groups includes quantities of photobiologically effective radiation. These quantities and the relative spectral evaluation functions of some photobiological effects are described. The measuring equipment for these photobiologically effective radiation quantities must fulfil special demands, which are stated. Some precise meters are described.
Handling material discontinuities in a nonconforming generalized finite element method enriched by plane waves. Part II. Curvilinear interfaces

In Part I (W. G. Facco et al., Microwave and Optical Technology Letters 54 (2012) 2709–2716), we introduced the q‐version of the nonconforming generalized finite element method (NC‐GFEM) for the Helmholtz equation where the interface between the media can be handled as piecewise linear segments. Here we continue the development of the NC‐GFEM for Helmholtz where the interface between the media can be handled as piecewise curvilinear. We address: (a) a new scheme of integration to evaluate the integral along the interfaces and (b) the mortar element method (MEM) as a substitute for the Lagrange multipliers. The MEM has the advantage of generating sparse and positive definite systems. Various numerical aspects affecting the NC‐GFEM efficiency are analyzed by solving a two‐dimensional scattering problem. The convergence of the method is also presented as a function of the number of plane wave directions. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1913–1919, 2014
NON-STANDARD ENERGY SPECTRA OF SHOCK-ACCELERATED SOLAR PARTICLES

We consider a numerical model for the shock acceleration of energetic ions in the magnetic environment of the solar corona. The model is motivated by observations of the deka-to-hecto-MeV proton energy spectra, ion and electron timing, and abundances in the beginning of major solar energetic particle (SEP) events, prior to the event's main phase associated with coronal mass ejection (CME) driven shock in the solar wind. Inasmuch as the obliquity of the CME-liftoff-associated shocks in solar corona and hence the seed-particle supply for the shock acceleration are essentially time dependent, a steady state energy spectrum of accelerated protons near the shock could not be attained. Energy spectrum of the SEP emission depends on the spatial and energy distribution of seed particles for the coronal shock acceleration, on the shock wave history, and on the location and scenario of the energetic particle escape into the interplanetary medium. We use a numerical model of the shock acceleration on a semicircular magnetic field line to learn a significance of different effects. If the shock geometry in a particular magnetic tube changes from nearly parallel to perpendicular, the resulting SEP spectrum in most distant sections of the tube, e.g., at the top of a transequatorial loop, resembles a wide beam, which is very different from the standard power-law spectrum that would be expected in a steady state. Possible escape of the shock-accelerated particles from more than one coronal location, stochastic re-acceleration, and the magnetic tube expansion can make the SEP spectra even more complicated.
Kinetic theory study of steady evaporation from a spherical condensed phase containing inert solid particles

Steady evaporation from a spherical and heterogeneous condensed body into vacuum is considered. Inert solid particles, initially embedded in the condensed phase, are liberated and collisionally accelerated by the evaporating gas molecules. A simple mathematical model for the flow is proposed and executed by the Direct Simulation Monte Carlo (DSMC) method. For small Knudsen numbers, the results are compared with a continuum solution including Knudsen layer corrections obtained by a moment method, demonstrating that these corrections are leading order effects in the treatment.
Stokes flow singularity at the junction between impermeable and porous walls

Abstract For two-dimensional, creeping flow in a half-plane, we consider the singularity that arises at an abrupt transition in permeability from zero to a finite value along the wall, where the pressure is coupled to the seepage flux by Darcy’s law. This problem represents the junction between the impermeable wall of the inflow section and the porous membrane further downstream in a spiral-wound desalination module. On a macroscopic, outer length scale the singularity appears like a jump discontinuity in normal velocity, characterized by a non-integrable $1/ r$ divergence of the pressure. This far-field solution is imposed as the boundary condition along a semicircular arc of dimensionless radius 30 (referred to the microscopic, inner length scale). A preliminary numerical solution (using a least-squares variant of the method of fundamental solutions) indicates a continuous normal velocity along the wall coupled with a weaker $1/ \sqrt{r} $ singularity in the pressure. However, inconsistencies in the numerically imposed outer boundary condition indicate a very slow radial decay. We undertake asymptotic analysis to: (i) understand the radial decay behaviour; and (ii) find a more accurate far-field solution to impose as the outer boundary condition. Similarity solutions (involving a stream function that varies like some power of $r$ ) are insufficient to satisfy all boundary conditions along the wall, so we generalize these by introducing linear and quadratic terms in $\log r$ . By iterating on the wall boundary conditions (analogous to the method of reflections), the outer asymptotic series is developed through second order. We then use a hybrid computational scheme in which the numerics are iteratively patched to the outer asymptotics, thereby determining two free coefficients in the latter. We also derive an inner asymptotic series and fit its free coefficient to the numerics at $r= 0. 01$ . This enables evaluation of the singular flow field in the limit as $r\ensuremath{\rightarrow} 0$ . Finally, a uniformly valid fit is obtained with analytical formulas. The singular flow field for a solid–porous abutment and the general Stokes flow solutions obtained in the asymptotic analysis are programmed in Fortran for future use as local basis functions in computational schemes. Numerics are required for the intermediate- $r$ regime because the inner and outer asymptotic expansions do not extend far enough toward each other to enable rigorous asymptotic matching. The logarithmic correction terms explain why the leading far-field solution (used in the preliminary numerics) was insufficient even at very large distances.
Two spacecraft observations of transient shocks and ejecta in the interplanetary medium

We compare Ulysses observations of 22 forward transient shocks (FTSs) and 11 ejecta during the first 19 months of its mission, with observations near Earth by IMP, in order to infer some properties of the propagation of these transient events in the interplanetary medium. We found that 13 of the 22 FTSs detected by Ulysses were also detected by IMP. The average of the mean radial transit speed of these 13 FTSs from 1 AU to Ulysses was about 504 km/s, which is slower than previous reports of transit speeds within 1 AU, suggesting shock deceleration beyond 1 AU. We found that whenever (in all cases) the two spacecraft detected the same FTS, the spacecraft were located within the same magnetic sector. During the period of the study we found 9 FTSs detected only by Ulysses and 10 FTSs detected only by IMP. For 16 of these shocks the two spacecraft were located within different magnetic sectors. The results suggest that magnetic sectors play a role in the propagation of transient shocks. Of the 11 ejecta detected by Ulysses, 7 of them also passed by IMP. The average of the mean radial transit speed of the 7 ejecta was about 407 km/s. In every case the radial width of the ejecta was larger at Ulysses than at IMP, showing a radial expansion with heliocentric distance. In the four events that we could estimate the shock-ejecta radial separation at 1 AU and Ulysses, we found that this radial distance was larger at Ulysses.
The number-intensity distribution of X-ray sources observed by Uhuru.

The Uhuru catalog of X-ray sources is used to analyze the number versus apparent-intensity relation of X-ray objects, by constructing (log N, log S)-plots similar to those used in radio astronomy. The source number distribution is corrected for nonuniform sky coverage of the spacecraft. Two distinct distributions for objects at low (less than 20 deg) and high (more than 20 deg) galactic latitude are discussed. The distribution for low galactic latitude objects (which are mainly galactic) gives further information on their location within the Galaxy and their intrinsic luminosity. The distribution for high-latitude objects is consistent with an extragalactic origin of these sources. Evidence from the longitudinal distribution of these objects is used to further demonstrate their extragalactic nature.
Infrared emission from dust structures surrounding herbig Ae/Be stars

IR observations in J, H, K, L, M, and 8-13 μm bands of Herbig Ae/Be stars located in the southern hemisphere are presented. These results enlarge an already existing data base, increasing the significance of the correlations which can be obtained from observational parameters. Silicate features detected both in emission and in absorption indicate the presence of dust around these objects. A first analysis based on two-color diagrams, polarization, and luminosity suggests that the spherical geometry for the dust distribution is a more common feature, with respect to the flattened structure