Miracle-dz/UniFAR-FTUs huggingface dataset:
Shock‐Tube Performance at Low Initial Pressure

An electron beam densitometer has been used to investigate the behavior of a conventional 1⅛‐in. i.d. shock tube operating at initial pressures of the order of 1 mm Hg. These experiments show that such a shock tube does not perform as predicted by simple theory. Most of the experiments were performed in argon with shock Mach numbers ranging between 1.2 and 7.0. The most striking observation was that for a given shock velocity, Ms = 1.6, the distance between the shock wave and contact surface as observed at the densitometer was proportional to initial pressure and independent of expansion chamber length over a tenfold range of tube length. At an initial pressure of 0.5 mm Hg the time interval between the arrival of the shock and the contact surface varied between 600 μsec at Ms = 1.2 and 20 μsec at Ms = 7.0. The diaphragm pressure ratio (Ar ‐ Ar) required to produce a shock of velocity Ms = 1.6 varied from 200 at an initial pressure of 0.25 mm Hg to 20 at an initial pressure of 50 mm Hg. For a given diaphr.
PCA-LBG-based algorithms for VQ codebook generation

Vector quantisation (VQ) codebooks are generated by combining principal component analysis (PCA) algorithms with Linde–Buzo–Gray (LBG) algorithms. All training vectors are grouped according to the projected values of the principal components. The PCA-LBG-based algorithms include (1) PCA-LBG-Median, which selects the median vector of each group, (2) PCA-LBG-Centroid, which adopts the centroid vector of each group, and (3) PCA-LBG-Random, which randomly selects a vector of each group. The LBG algorithm finds a codebook based on the better vectors sent to an initial codebook by the PCA. The PCA performs an orthogonal transformation to convert a set of potentially correlated variables into a set of variables that are not linearly correlated. Because the orthogonal transformation efficiently distinguishes test image vectors, the proposed PCA-LBG-based algorithm is expected to outperform conventional algorithms in designing VQ codebooks. The experimental results confirm that the proposed PCA-LBG-based algorithms indeed obtain better results compared to existing methods reported in the literature.
C-H Bond Formation in Carbon Grains by Exposure to Atomic Hydrogen: The Evolution of the Carrier of the Interstellar 3.4 Micron Band

We present the results of a systematic study on the interaction of nano-sized carbon grains with atomic hydrogen. The effects of H processing have been analyzed by infrared spectroscopy. The samples were irradiated with fluences ranging between 9.2 × 1016 and 1.3 × 1020 H atoms cm-2. Hydrogen atoms lead to the activation of the aliphatic C–H stretching and bending modes, whose intensity increases with exposure until saturation of hydrogenation. The plateau value of the absorption coefficient per unit mass of material at 3.4 μm is 1.6 × 103 cm2 g-1. The estimated cross section of C–H bond formation by H atoms for carbon particles is σf = (1.9 ± 0.5) × 10-18 cm2 per H atom, as derived from the behavior of the 3.4 μm band intensity as a function of the H atom fluence. We have found that the C–H bond formation depends on the structure of the carbon material that is exposed to atomic hydrogen. In view of the basic role of the hydrogenation of carbon particles by H atoms in interpreting the presence of the 3.4 μm band in the diffuse interstellar medium, the behavior of carbon materials under H processing becomes a fundamental criterion for constraining their applicability as analogs of the interstellar aliphatic component. The 3.4 μm band and the doublet at 6.86 and 7.26 μm of carbon particles processed by H atoms reproduce the peak positions and the relative intensities of those observed in the spectrum of interstellar dust toward the Galactic center. The estimation of the formation cross section of C–H bonds by H atoms, together with the previously determined destruction cross section by UV photons, allows a complete description of the evolution of the interstellar aliphatic carbon component due to UV and H processing. The conclusion of our analysis is that the interstellar component (i.e., the C–H bonds in the CH2 and CH3 groups) responsible for the 3.4 μm stretching band and the associated bending features at 6.85 and 7.25 μm is formed in the diffuse medium, since the carrier readily loses memory of its birthsite, wherever it is, because of interstellar processing, which determines a new equilibrium value for its degree of hydrogenation.
Axisymmetric oscillations of an opposing jet from a hemispherical nose

The flowfield around a hemispherical nose with a sonic opposing jet in a freestream of Mach 2.5 is computed by a time-accurate algorithm using the axisymmetric Navier-Stokes equations. Five total pressure ratios of a jet to a freestream, 0.816 ∼ 1.633, are examined. The results obtained strongly depend on the total pressure ratio as the previous experimental results did. In some cases, the computed flowfield oscillates intensely in which the drastic change of the jet structure and the surrounding pressure takes place. The flowfield changes from the stable flow to the unstable flow for the same total pressure ratio as in the experiment The mechanism of the oscillations and the condition of transition between both types of flow are interpreted physically on the basis of unsteady numerical solutions here.
The Trumpler 14 photodissociation region in the Carina Nebula

We report the results of observations of the fine-structure emission lines (C ) 158 µ ma nd (O )6 3µm using FIFI on the Kuiper Airborne Observatory (KAO) and the Long Wavelength Spectrometer (LWS) on board ISO, towards the molecular cloud associated with the stellar cluster Trumpler 14 (Tr 14) in the Carina Nebula. These data are compared with selected CO and CS transitions obtained with the SEST as well as IRAS and MSX images to produce a detailed view of the morphology and the physical conditions prevailing in the photodissociation region (PDR) at the interface between the ionized gas and the molecular dust lane. The relative intensity distribution observed for the various tracers is consistent with the stratification expected for a molecular cloud seen edge-on and exposed to a radiation field of ≈10 4 G0, which is dominated by the most massive stars of Tr 14. The grain photoelectric heating efficiency, � , is estimated to be ≈5 × 10 −3 and is comparable to other galactic PDRs. The molecular gas has a complicated velocity structure with a high velocity dispersion resulting from the impact of the stellar winds arising from Tr 14. There is evidence of small-scale clumping with a very low volume filling factor. Despite the rich concentration of massive O stars in Tr 14 we find that the parameters of the PDR are much less-extreme than those of the Orion and M 17 massive star-forming regions.
Impact of agricultural land use on distribution of microbial biomass and activity within soil aggregates

The presence of aggregates of various sizes in the soil is an important condition for soil carbon sequestration. In this system, microbial biomass is a key link. This work was devoted to the study of the influence of land use systems on the distribution of SOС, MB‐SIR, microbial activity and eco‐physiological indices (qCO2, QR, MB‐SIR/SOС and qCO2/SOС) in relation to the size of soil aggregates. The distribution of SOС, MB‐SIR and mineralization activity among the aggregates was heterogeneous. In the soil of crop rotation, high mineralization activity and MB‐SIR were found in the aggregates 0.5–0.1 mm, in the monoculture soil in aggregates <0.1 mm and in the control soil in the aggregates 1–0.25 mm. There was a general trend towards a decrease in microbial activity, MB‐SIR and SOС availability with an increase in aggregate size. In agricultural soils, microbial activity was determined by large aggregates (>5 mm), while in the control soil, by the aggregates 5–1 mm. Depending on the type of site and the size of aggregates, the differences in microbial metabolism were revealed. The qCO2 and QR values decreased, and the MB‐SIR/SOС and qCO2/SOС increased in the series: control soil > crop rotation > monoculture. In the control soil, the values of the eco‐physiological indices decreased with decreasing aggregate size. And vice versa, in agricultural soils, these parameters were the highest in the microaggregates (<0.25 mm). The monoculture soil, in contrast to the control soil and crop rotation soil, turned out to be more energy efficient.
The Development Mechanism for Tibetan Plateau Warm Vortices

Abstract The low-level cyclonic vortices which form over the Tibetan Plateau in the summer monsoon season are major rain-producing systems and have the potential to trigger cyclogenesis on the lee side when they move off the plateau. Two cases of the plateau vortices which occurred in July 1979 are studied. The characteristics of the vertical structure in their developing stage, and the circulation condition favorable for the eastward movement in the mature stage are diagnosed and presented by use of FGGE IIIb datasets. Numerical simulations with real data were performed using the GFDL limited-area mesoscale simulation model. Results suggest that the latent heating is an essential driving force for the development of the vortices studied here. The analysis of a continuous CISK model with a basic state resembling that actually observed over the summer plateau shows that the predicted unstable mode has a preferred scale, growth rate and vertical structure, all of which are qualitatively comparable to observ.
Experimental Identification of Transient Dynamics for Supersonic Inlet Unstart

Successful realization of dual-mode scramjet engines will require closed-loop control schemes to eliminate the occurrence of inlet unstart. An important step toward this goal is the development of dynamic models for shock system motion inside the inlet isolator under varying flow conditions. In this paper, shock motion models are developed based on fast-response pressure measurements made along the wall of the isolator (straight channel) downstream of a Mach 1.8 nozzle. The shock system can be perturbed by changing the stagnation pressure with an upstream valve and/or by changing the backpressure with a downstream flap. In particular, the shock’s transient dynamics are modeled, which govern the unstart process and are induced by changing pressure-boundary conditions, by employing system identification techniques. The result is a partially nonlinear dynamic model that reveals the possibility of partitioning the nonlinear behavior from the linear dynamics with relative ease. A second dynamic model is then g.
Influence of the external electrical circuit on the regimes of a nanosecond repetitively pulsed discharge in air at atmospheric pressure

This paper presents 2D simulations of nanosecond repetitively pulsed discharges in air at atmospheric pressure coupled with a model of the external electrical circuit used in experiments. Then, during the pulsed discharge, the voltage applied to the electrodes varies in time as a function of the time dependent value of the plasma channel conductivity. In this work, we have simulated several consecutive nanosecond pulsed discharges between two point electrodes in air initially at 1000 K at a frequency of 10 kHz. First, we have simulated three consecutive nanosecond spark discharges. We have shown that the air temperature increases significantly pulse after pulse in the discharge channel. As a consequence, for the three consecutive simulated nanosecond spark discharges, we have put forward a decrease in the discharge radius, pulse after pulse. Then, to further limit the discharge current, a ballast resistance R has been added into the electrical circuit and the results are presented for seven consecutive nanosecond discharges. For a value of R = 1000 Ω in the conditions studied in this work, we have shown that the first nanosecond discharges are in the glow regime, with a small gas heating per pulse. However, as the number of pulses increases due to the gas heating by each pulse, the discharge may transit to a multipulse nanosecond spark regime. For a higher value of R = 10 000 Ω, we have put forward that the gas heating by each nanosecond discharge becomes negligible and then the multipulse nanosecond discharge remains in this case in a stable ‘quasi-periodic’ multipulse glow regime.
Ensemble statistics as units of selection

The current study investigated whether attentional mechanisms operate on ensembles as higher-order units for selection. In Experiment 1, we presented sets of circles and asked participants to compare the mean sizes of the sets while concurrently detecting a small probe appearing at a centroid of one of the sets. We found that, both with and even without the task instruction to favour larger mean sizes, people's mean size judgement was more accurate for the sets with larger mean sizes. In addition, detection of the probe appearing in the set with the largest mean size was facilitated by a matching task instruction. However, when the task instruction favoured smaller mean sizes, mean size judgement became more accurate for the sets with smaller mean sizes. These results suggest that attentional selection can be based on ensembles. In Experiment 2, we found further evidence that attention was directed towards the centroid of an ensemble, rather than towards an individual member of the ensemble. Together, these results suggest that attentional modulation can operate at the level of ensembles instead of selecting individuals separately and that the centroid of an ensemble can be the locus of selection based on an ensemble.
Note on the Transmission and Reflection of Wave Packets by Potential Barriers

In previous studies, by the methods of wave mechanics, of one-dimensional motion of particles in cases in which there are intervals in which the value of the potential energy function $V(x)$ exceeds the value of the total energy $E$, attention has been confined to wave functions of the form $f(x, E)\mathrm{exp}(\ensuremath{-}\frac{2\ensuremath{\pi}\mathrm{iEt}}{h})$. In the present note wave packets are considered, instead of these trains of waves.
Observation of perpendicular anisotropy in granular magnetic solids

Granular Co‐Ag materials with low Co contents exhibit giant magnetoresistance and single‐domain magnetic properties. In this paper, we discuss unusual hysteresis behavior that we have observed in Co‐rich samples, where the magnetization is approximately linear with the applied field up to saturation, and the coercivity and remnant magnetization are both nearly zero. We attribute this unusual behavior to a perpendicular anisotropy that depends on the nanostructure in the phase‐segregated materials. These results are corroborated by magnetic domain imaging using scanning electron microscopy with polarization analysis.
Numerical simulation of three dimensional transonic flows

Abstract : The three dimensional flows over a projectile have been computed using an implicit, approximately factored, partially flux-split algorithm. A simple composite grid scheme has been developed in which a single grid is partitioned into a series of smaller grids for application which require an external large memory device such as the SSD of the CRAY X-MP/48 or multi-tasking. The accuracy and stability of the composite grid scheme has been tested by numerically simulating the flow over an ellipsoid at angle of attack and comparing the solution with a single grid solution. The flow field over a projectile at M = 0.96, 1.1. and 4 deg angle of attack has been computed using a fine grid and compared with experiment. Keywords: Asymmetric shocks; Navier Stokes equations.
A FUNCTION-ALGEBRA VARIANT OF A THEOREM OF BOHR-van KAMPEN

According to the classical Bohr-von Kampen theorem, if a function on a connected compact group is continuous and has no zeros then it has (to within a character) a continuous logarithm. This theorem can be extended to an arbitrary commutative Banach algebra in whose group of automorphisms a connected compact group is presented. Bibliography: 10 titles.
Transmission electron microscopy investigation and first-principles calculation of the phase stability in epitaxial CuInS2 and CuGaSe2 films

Ordering of metal atoms in CuInS2 and CuGaSe2 thin films grown by vapor-phase epitaxy on Si (001) and GaAs (001) substrates were studied using transmission electron microscopy and first-principles total energy calculations. Chalcopyrite and CuAu-like orderings of the metal atoms were observed coexisting in CuInS2 films, while only chalcopyrite ordering was found in CuGaSe2 films. First-principles total energy calculations find that the formation enthalpy difference between chalcopyrite and CuAu-like phases of CuInS2 is very small (2 meV/atom), while it is large for CuGaSe2 (9 meV/atom), indicating that the existence of CuAu-like phase in the nominally chalcopyrite semiconductors is controlled by bulk thermodynamics.
Application of double Fourier series to the shallow-water equations on a sphere

The spectral transform method using a double Fourier series as orthogonal basis functions as in Cheong (2000, J. Comput. Phys.157, 327) is extended to the solution of the shallow-water equations on a sphere. A spectral filter which mimics the implicit diffusion process with the third-order Laplacian operator is applied to the spectral components of predicted variables to prevent the aliasing error or nonlinear instability. For a predicted variable the spectral filter needs only about 76N2 operations with N being the zonal and meridional wavenumber truncation. The use of the filter even at every time step does not deteriorate the computational efficiency of the double-Fourier-series model, which comes from the availability of FFTs. The filter requires an additional memory for only 6N2 elements, so the total memory space of O(N2) is sufficient in the present model. Along with the incorporation of the polar filter, the semi-implicit time-stepping procedure contributes to a significant increase in the time-step size. A standard test set proposed by Williamson et al. (1992, J. Comput. Phys.102, 211) is used to evaluate the errors associated with the new method for various resolutions. It is shown that as a whole the accuracy of the method is comparable to that of spherical harmonics model (SHM) though the present method provides more accurate time integration for some cases but does not for other cases. A long time-integration far beyond the period specified in the standard test set also illustrates almost the same accuracy as that given by the SHM. The relative efficiency of the method to the SHM appears from the resolution of 256×128 transform grids, and it becomes significant for resolutions higher than 512×256. The computational efficiency is expected to increase further with an improved FFT algorithm. The test results suggest that the new method could be extended to three-dimensional numerical models used for weather prediction.
Effects of solute mass transfer on the stability of capillary jets

The effects of mass transfer (e.g. via evaporation) of surface-active solutes on the hydrodynamic stability of capillary liquid jets are studied. A linear temporal stability analysis is carried out yielding evolution equations for systems satisfying general non- linear kinetic adsorption relations and accompanying surface constitutive equations. The discussion of the instability mechanism associated with the Marangoni effect clarifies that solute transfer into the jet is destabilizing whereas transfer in the opposite direction reduces instability. The general analysis is illustrated by a system satisfying Langmuir-type kinetic relations. Contrary to a clean system (i.e. in the absence of surfactants), reduced jet viscosity may lead to a substantial reduction in perturbation growth. Furthermore, the Marangoni effect gives rise to an overstability mechanism whereby perturbations whose dimensionless wavenumbers exceed unity grow with time through oscillations of increasing amplitude. The common diffusion-control approximation constitutes an upper bound which substantially overestimates the actual growth of perturbations. Considering solutes belonging to the homologous series of normal alcohols in water–air systems, the intermediate cases (e.g. hexanol–water–air which is ‘mixed-control’) are the most susceptible to Marangoni instability.
The relationship between vocal pitch feedback error and event-related brain potentials

Understanding the neural processing of auditory feedback during speech is essential to the development of a comprehensive model of speech motor control. Currently, the relationship between the magnitude of errors detected in feedback and the evoked neural responses is unclear. We exposed speakers to sudden changes in vocal pitch that ranged from 0 to 400 cents in magnitude. Vocal responses and auditory event-related potentials (ERPs: P1-N1-P2-N2 components) were measured. Results showed that vocal response magnitudes were relatively consistent when speakers were exposed to small feedback perturbations ( 300 cents) caused decreased vocal response magnitudes. P1 amplitudes showed a non-specific increase when feedback was perturbed. N1 amplitudes demonstrated more specificity: smaller feedback perturbations evoked one size of response, while larger feedback perturbations elicited a larger response. P2 amplitudes increased with increases in the feedback perturbation magnitud.
Stellar wind regimes of close-in extrasolar planets

Close-in extrasolar planets of Sun-like stars are exposed to stellar wind conditions that differ considerably from those for planets in the solar system. Unfortunately, these stellar winds belong to the still unknown parameters of these planetary systems. On the other hand, they play a crucial role in a number of star-planet interaction processes that may lead to observable radiation events. In order to lay a foundation for the investigation of such interaction processes, we estimate stellar wind parameters on the basis of the solar wind model by Weber & Davis and study the implications of the stellar magnetic fields. Our results suggest that in contrast to the solar system planets, some close-in extrasolar planets may be obstacles in a sub- Alfvenic stellar wind flow. In this case, the stellar wind magnetic pressure is comparable to or even larger than the dynamic flow pressure. We discuss possible consequences of these findings for the wind-exoplanet interactions. Further, we derive upper limit estimates for the energies such stellar winds can deposit in the exoplanetary magnetospheres. We finally discuss the implications the sub-Alfvenic environment may have on the star-planet interaction.
Cubical Species and Nonassociative Algebras

We lay down the foundations of a theory ofcubical species, as a variant of Joyal's classical theory of species (A. Joyal,Adv. Math.42(1981), 1? 82). Informally, a cubical species associates in a functorial way a set of structures to each hypercube. In this context, the hyperoctahedral groups replace the symmetric groups. We analyze cubical species, molecular cubical species, and basic operations among them, along with explicit examples. We show, in particular, that the cubical product gives rise, in a natural way, to a commutative nonassociative ring of formal power series. We conclude with a detailed analysis of this nonassociative ring.