Miracle-dz/UniFAR-FTUs huggingface dataset:
Turbulence in the liquid phase of a uniform bubbly air–water flow

The paper describes studies of the turbulence of the liquid in a bubbly, grid-generated turbulent flow field. Laser-Doppler and hot-film anemometry are used for the experimental investigation. It is found that the turbulent kinetic energy increases strongly with the void fraction α. Roughly speaking, there exist two distinct regimes: the first one corresponds to low value of α, where hydrodynamic interactions between bubbles are negligible, and the second one to higher values, for which, owing to their mutual interactions, the bubbles transfer a greater amount of kinetic energy to the liquid. The Reynolds stress tensor shows that the quasi-isotropy is not altered. At low enough values of α, the difference between the turbulent kinetic energy in the liquid phase and the energy associated with the grid-generated turbulence proves to be approximately equal to the intensity of the pseudo-turbulence, defined as the fluctuating energy that would be induced by the motion of the bubbles under non-turbulent conditions. The one-dimensional spectra exhibit a large range of high frequencies associated with the wakes of the bubbles and the classical $-\frac{5}{3}$ power law is progressively replaced by a $-\frac{8}{3}$ dependence.
Lattice Distortion Coupled with Magnetic Ordering in a Triangular Lattice Antiferromagnet CuCrO2

We investigated magnetostrictive properties of a triangular lattice antiferromagnet CuCrO 2 showing an incommensurate proper-screw spin order by means of x-ray diffraction and strain gauge measurements. A deformation of the triangular lattice plane leading to a lowered crystallographic symmetry was found upon the magnetic ordering, which demonstrates a strong spin–lattice coupling in this system. The resultant multiple structural domains can be successfully arranged by magnetic field cooling procedures. We discuss the relationship between the lattice distortion and incommensurability in CuCrO 2 .
Comment on ‘An improved score interval with a modified midpoint for a binomial proportion’

Yu et al. [An improved score interval with a modified midpoint for a binomial proportion. J Stat Comput Simul. 2014;84:1022–1038] propose a novel confidence interval (CI) for a binomial proportion by modifying the midpoint of the score interval. This CI is competitive with the various commonly used methods. At the same time, Martín and Álvarez [Two-tailed asymptotic inferences for a proportion. J Appl Stat. 2014;41:1516–1529] analyse the performance of 29 asymptotic two-tailed CI for a proportion. The CI they selected is based on the arcsin transformation (when this is applied to the data increased by 0.5), although they also refer to the good behaviour of the classical methods of score and Agresti and Coull (which may be preferred in certain circumstances). The aim of this commentary is to compare the four methods referred to previously. The conclusion (for the classic error α of 5%) is that with a small sample size (≤80) the method that should be used is that of Yu et al.; for a large sample size (n ≥ 100), the four methods perform in a similar way, with a slight advantage for the Agresti and Coull method. In any case the Agresti and Coull method does not perform badly and tends to be conservative. The program which determines these four intervals are available from the address http://www.ugr. es/local/bioest/Z_LINEAR_K. EXEhttp://www.ugr. es/local/bioest/Z_LINEAR_K. EXE.
Control for a class of non-linear singularly perturbed systems subject to actuator saturation

This study considers the control problem for a class of non-linear singularly perturbed systems (SPSs) subject to actuator saturation. A sufficient condition for the existence of state-feedback controllers to achieve a prescribed stability bound is proposed and the corresponding basin of attraction is estimated. Then a convex optimisation problem is formulated, by which an optimal controller can be obtained to achieve a prescribed stability bound and simultaneously maximise the estimate of the basin of attraction of the SPSs for any allowable singular perturbation parameter. Furthermore, a stability condition is established, which improves the existing stability bound analysis methods for a class of non-linear SPSs. Finally, examples are given to show the advantages and effectiveness of the obtained results.
The modified cuinulant expansion for two-dimensional isotropic turbulence

The two-dimensional isotropic turbulence in an incompressible fluid is investigated using the modified zero fourth-order cumulant approximation. The dynamical equation for the energy spectrum obtained under this approximation is solved numerically and the similarity laws governing the solution in the energy-containing and enstrophy-dissipation ranges are derived analytically. At large Reynolds numbers the numerical solutions yield the k−3 inertial subrange spectrum which was predicted by Kraichnan (1967), Leith (1968) and Batchelor (1969) assuming a finite enstrophy dissipation in the inviscid limit. The energy-containing range is found to satisfy an inviscid similarity while the enstrophy-dissipation range is governed by the quasi-equilibrium similarity with respect to the enstrophy dissipation as proposed by Batchelor (1969). There exists a critical time tc which separates the initial period (t < tc) and the similarity period (t > tc) in which the enstrophy dissipation vanishes and remains non-zero respectively in the inviscid limit. Unlike the case of three-dimensional turbulence, tc is not fixed but increases indefinitely as the viscosity tends to zero.
Review of biomedical optical imaging—a powerful, non-invasive, non-ionizing technology for improving in vivo diagnosis

This paper reviews the recent developments in the field of biomedical optical imaging, emphasizing technologies that have been moved from ‘bench top to bedside’. Important new developments in this field allow for unprecedented visualization of the tissue microstructure and enable quantitative mapping of disease-specific endogenous and exogenous substances. With these advances, optical imaging technologies are becoming powerful clinical tools for non-invasive and objective diagnosis, guided treatment and monitoring therapies. Recent developments in visible and infrared diffuse spectroscopy and imaging, spectral imaging, optical coherence tomography, confocal imaging, molecular imaging and dynamic spectral imaging are presented together with their derivative medical devices. Their perspectives and challenges are discussed.
Validity of the rotating wave approximation in the driven Jaynes–Cummings model

In this paper we define, in the context of dynamical algebras, a set of operators that are suitable for studying any relevant quantity related to the two-level Jaynes–Cummings model (JCM). We study the usual JCM with and without the rotating wave approximation (RWA), and then we add the presence of an external field. In this last case we find that in the strong driving regime there are significant differences between the results obtained with the RWA and without it. This holds even for the case in which the usual requirements for applying the RWA without an external driving are fulfilled.
Einstein-Rosen String Cosmological Model in Barber's Second Self-Creation Theory

Field equations in the presence of cosmic string source are obtained in Barber's second self-creation theory of gravitation (Gen. Relativ. Gravit.14, 117 (1982)) with the aid of Einstein–Rosen cylindrically symmetric metric. A static vacuum model and a nonstatic exact string cosmological model are presented which represents Reddy string (Astrophys. Space Sci.286, 365 (2003)) in self-creation theory. Some physical and kinematical properties of the model are also discussed.
A Database of Cepheid Distance Moduli and Tip of the Red Giant Branch, Globular Cluster Luminosity Function, Planetary Nebula Luminosity Function, and Surface Brightness Fluctuation Data Useful for Distance Determinations

We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The database includes all data published as of 1999 July 15. The main strength of this compilation resides in the fact that all data are on a consistent and homogeneous system: all Cepheid distances are derived using the same calibration of the period-luminosity relation, the treatment of errors is consistent for all indicators, and measurements that are not considered reliable are excluded. As such, the database is ideal for comparing any of the distance indicators considered, or for deriving a Cepheid calibration to any secondary distance indicator, such as the Tully-Fisher relation, the Type Ia supernovae, or the fundamental plane for elliptical galaxies. This task has already been undertaken by Ferrarese et al., Sakai et al., Kelson et al., and Gibson et al. Specifically, the database includes (1) Cepheid distances, extinctions, and metallicities; (2) reddened apparent λ5007 Å magnitudes of the PNLF cutoff; (3) reddened apparent magnitudes and colors of the turnover of the GCLF (in both the V and B bands); (4) reddened apparent magnitudes of the TRGB (in the I band) and V-I colors at 0.5 mag fainter than the TRGB; and (5) reddened apparent surface brightness fluctuation magnitudes measured in Kron-Cousin I, K′, and Kshort, and using the F814W filter with the Hubble Space Telescope (HST) WFPC2. In addition, for every galaxy in the database we give reddening estimates from IRAS/DIRBE as well as H I maps, J2000 coordinates, Hubble and T-type morphological classification, apparent total magnitude in B, and systemic velocity.
Nature of deep center emissions in GaN

Photoluminescence (PL) emission spectroscopy was employed to probe the nature of deep center emissions in GaN. The room temperature PL spectrum measured in the infrared (IR) region revealed an emission band centered around 1.23 eV. Based on detailed analysis of both the IR and visible emission spectra, we suggest that this emission band is a band-to-impurity transition involving a deep level complex consisting of a gallium vacancy and an oxygen atom sitting on one of the neighboring nitrogen sites; the (VGa–ON)2− charge state of (VGa–ON)2−/1−. Two electronic structures, which arise due to two different configurations of (VGa–ON)2−/1−, with ON either along the c-axis (axial configuration) or in one of the three equivalent tetrahedral positions (basal configuration), were observed. Our result also provides explicit evidence that both the yellow luminescence band and the 1.23 eV emission line in GaN are related to a common deep center, which is believed to be (VGa–ON)2−/1−.
Ultraviolet and Optical Spectra of High-Ionization Seyfert Galaxies with Narrow Lines

Ultraviolet and optical spectra are presented for three unusual Seyfert galaxies (Mrk 1239, Mrk 42, and Mrk 493) that resemble Seyfert 1 galaxies in that they have strong high-ionization lines and strong nonstellar continua, but resemble Seyfert 2 galaxies in that the widths of their permitted lines are as narrow as the widths of their forbidden lines. The He II lambda 1640 and He II lambda 4686 lines are used to determine an upper limit to the reddening experienced by the emission lines. Published optical data show that these particular high-ionization narrow-line (HINL) Seyferts have low lambda 5007 H beta ratios and strong Fe II emission, which suggest the presence of high-density regions. The low Lalpha/H-beta ratios in these objects indicate that high-density clouds are indeed present, and, like the broad-line region clouds in Seyfert 1 galaxies, these clouds have large optical depths with partially ionized zones. Overall, the line ratios and continuum fluxes of these particular HINL Seyferts are indistinguishable from those of broad-lined Seyfert 1 galaxies. 20 refs.
Magnetic field turbulence spectra observed by the wind spacecraft

We are presenting a new Wind MFI high time resolution data set covering 1994-2012. The time resolution of the data, normally 92 ms and occasionally 46 and 184 ms, obtained as onboard averages of the 22.7 ms measurements, allows investigation of both the inertial and dissipation ranges of the magnetic field turbulence. Using this data set we have analyzed the magnetic field turbulence spectra of more than 100,000 hourly solar wind intervals and computed the inertial and dissipation range spectral indices. Our initial results indicate that the spectral indices in the solar wind are distributed as −1.67 ± 0.22 in the inertial range and as −2.76 ± 0.72 in the dissipation range. There is a slight negative correlation between the indices and a region of overlapping inertial and dissipation range indices, where the spectral break may completely disappear.
The binary phase-only 1/f joint transform correlator

Abstract In this paper we present a new approach to implementing the joint transform correlator based on a single ferroelectric spatial light modulator used as a binary phase-only device. The correlator is a 1/f joint transform correlator which uses two passes through the optical system to generate the peaks. The input scene and reference image are encoded with a chequerboard pattern to produce a spectrum with no zero order. The spectrum is then convolutionally binarised and replayed on the spatial light modulator. Experimental results demonstrate strong correlation peaks with a zero order in the correlation plane reduced to 6dB below the correlation peaks. The correlator also demonstrates enhanced differentiation between closely correlated images.
Proton beam generation of whistler waves in the Earth's foreshock

We show that proton beams, often observed upstream of the Earth's bow shock and associated with the generation of low-frequency hydromagnetic fluctuations, are also capable of generating whistler waves. The waves can be excited by an instability driven by two-temperature streaming Maxwellian proton distributions which have T⊥/T∥ ≫ 1. It can also be excited by gyrating proton beam distributions. These distributions generate whistler waves with frequencies ranging from 10 to 100 times the proton cyclotron frequency (in the solar wind reference frame) and provide another mechanism for generating the “1-Hz” waves often seen in the Earth's foreshock.
Controllable and enhanced nanojet effects excited by surface plasmon polariton

Nanojet effects excited by surface plasmon polariton at the shadow-side surfaces of dielectric microdisks positioned on gold films are reported. The surface plasmon nanojet can propagate over several optical wavelengths while still maintaining a subwavelength full-width at half-maximum transverse. Due to the nature of surface plasmon wave, the electric field of the highly confined nanojet at metal-dielectric interface is enhanced by about 30 times. By varying thickness of the dielectric microdisk, the formation of surface plasmon polariton nanojet can be flexibly controlled. The surface plasmon polariton nanojet shows great promise for enhanced Raman scattering and integrated plasmonic circuits.
The Focus of Beam Using Optical Transformation

A novel scheme is proposed to achieve beam focus by applying the method of embedded coordinate transformation[1] in this paper. The focus degree of electromagnetic waves is determined by the structure parameters in the transformation region. Theoretical analysis and simulating results are given to demonstrate that our design is feasible and practical, and might have some potential applications in solar cell plate. Moreover, full-wave numerical simulations do further work to confirm the theoretical analysis.
Tunable spin wave dynamics in two-dimensional Ni80Fe20 nanodot lattices by varying dot shape

We demonstrate tunable spin wave spectrum in two-dimensional Ni80Fe20 nanodot lattices by varying dot shape. A single collective mode in elliptical dot lattices transforms into three distinct modes for the half-elliptical, rectangular, and diamond dot lattices, albeit with different peak frequencies and intensities. A drastic change is observed for the triangular dots, where eight modes covering a broad band are observed. Using micromagnetic simulations, we characterized the modes as different localized, extended, and quantized modes, whose frequencies and spatial profiles are determined by a combination of internal field profiles within the nanodots and the stray magnetic field within the lattice.
First- and Second-Order Sufficient Optimality Conditions for Bang-Bang Controls

We study $L_{1}$-local optimality of a given control $\tu$ in the time-optimal control problem for an affine control system. We start with the necessary optimality condition---the Pontryagin maximum principle, which selects the candidates for minimizers, the extremal controls. Generally the corresponding Pont\-ryagin extremals consist of bang-bang and singular subarcs, separated by switching points. In the present paper we treat only pure bang-bang extremals. We introduce extended first and second variations along a bang-bang extremal and establish first- and second-order sufficient optimality conditions for the bang-bang extremal controls.
Experiments for modelling the biodegradation of wastewater in sequencing batch reactors

Three types of wastewater were considered: typical municipal wastewater and the effluent of a dairy industry, both polluted with organic carbon and nitrogen, and wastewater typical of a chemical industry, containing toxic or recalcitrant compounds (4-chlorophenol). Sequencing batch reactors (SBRs) were considered. Process experiments were performed to provide experimental data for parameter identification of the dynamical models of the SBRs. The processes were instrumented with sensors to measure O2, NH3, T, pH, OUR, and other off line measurements (e.g.: NO2 − and NO3 −, COD, phenol concentration, microbiological counts and activities) in order to study more accurately the behaviour of the biomasses. However, the general idea is to design a system with a minimal number of sensors.
ZnO nanobarbed fibers: Fabrication, sensing NO2 gas, and their sensing mechanism

ZnO nanobarbed fibers (NBFs) are synthesized by the epitaxial growth of 1–D ZnO nanorods (NRs) on ZnO nanofibers (NFs) via electrospinning and chemical bath deposition. The change in resistance of the NBFs in the presence or absence of a gas was explained using the surface depletion model and modified grain boundary model, in which the junction points of the NFs and NRs are considered. The NBF structure showed extraordinary NO2 sensing performance for gas concentrations up to 30 ppb. This indicates that NBF structures have great potential for use as gas sensing materials.
The Learning Component of Dynamic Allocation Indices

*This article is free to read on the publisher's website* For a multiarmed bandit problem with exponential discounting the optimal allocation rule is defined by a dynamic allocation index defined for each arm on its space. The index for an arm is equal to the expected immediate reward from the arm, with an upward adjustment reflecting any uncertainty about the prospects of obtaining rewards from the arm, and the possibilities of resolving those uncertainties by selecting that arm. Thus the learning component of the index is defined to be the difference between the index and the expected immediate reward. For two arms with the same expected immediate reward the learning component should be larger for the arm for which the reward rate is more uncertain. This is shown to be true for arms based on independent samples from a fixed distribution with an unknown parameter in the cases of Bernoulli and normal distributions, and similar results are obtained in other cases.
Behaviour of a sphere on a rough inclined plane

The tlifferent states of a bail on a rough indmed plane are analyzed from experimental results and numencal simulations. The conditions of static equilibrium are given. The control parameters are the inclination angle of the plane antl the surface roughness. Then, we propose a «phase tliagram » for the motion of the bail. These results are expectetl to be useful m untlerstantling the ongin of the segregation effects on the surface of a sandpile.
The Role of Outflows and C Shocks in the Strong Deuteration of L1689N

Recent detections of doubly deuterated ammonia and formaldehyde in L134N and L1689N have renewed interest in deuterium fractionation in cold, dense molecular gas. Chemical models show that the level of fractionation depends critically on the physical conditions, namely, the temperature and density of the molecular gas. Therefore, detailed studies of cold, dense molecular cores are required to constrain the existing chemical networks. We have mapped the core of the remarkable star-forming molecular cloud L1689N in a number of molecular tracers, including singly deuterated species, in order to obtain detailed information on the morphology and kinematics of the molecular gas, as well as the physical conditions in the dense core and the shocked regions associated with the molecular outflows emanating from the embedded far-infrared source IRAS 16293-2422. Our data suggest the presence of two regions of interaction between the molecular outflows and the dense ambient cloud, one of them associated with the SiO peak E1, the other one near the peak of deuterated and doubly deuterated molecular species ~90'' east of the IRAS source. The observed intensities of the CO (3-2), (4-3), and (6-5) emission at these two locations are consistent with those predicted by C shock models with velocities of 15-25 and 8-10 km s-1, respectively. The relatively low shock velocity derived for the deuterium peak explains why no SiO emission has been detected at this location. Deuterated molecular species, such as DCO+ and DCN, in the core of L1689N are kinematically and morphologically distinct from other molecular tracers of the dense gas, such as HCO+, H13CO+, and HCN. The peak of deuterated molecules is also displaced from the extended millimeter dust continuum source located in this region. We use formaldehyde observations to derive the excitation conditions in the dense gas and, subsequently, the D/H ratios in HCO+ and HCN at several locations via large velocity gradient modeling. These ratios are typically ~1% toward the locations of the IRAS source and the SiO peak E1, with much higher values, ~10%, derived toward the deuterium peak. These values fall within the range of predictions of gas-phase chemical models for dense and cold gas, provided that significant accretion of H2O, CO, and other molecular species on the dust grains has occurred. However, some discrepancies between the observations and model predictions remain. For example, contrary to gas-phase model predictions, we derive a higher deuterium fractionation in HCN compared to HCO+.
Controllability of a slowly rotating Timoshenko beam

Consider a Timoshenko beam that is clamped to an axis perpendicular to the axis of the beam. We study the problem to move the beam from a given initial state to a position of rest, where the movement is controlled by the angular acceleration of the axis to which the beam is clamped. We show that this problem of controllability is solvable if the time of rotation is long enough and a certain parameter that describes the material of the beam is a rational number that has an even numerator and an odd denominator or vice versa.
Temporal symmetry of individual filaments in different spatial symmetry filaments pattern in a dielectric barrier discharge

The temporal behavior of individual filament in different spatial symmetry filaments patterns in dielectric barrier discharge is investigated by using an optical method. A series of return maps of the discharge moments of individual filaments is given. It is found that the temporal symmetry of individual filament changes with the change of the spatial symmetry of filaments pattern as the applied voltage increases. The role of wall charges for this phenomenon is analyzed.