Miracle-dz/UniFAR-FTUs huggingface dataset:
The 3.3 Micron and Extended Red Emissions in Interstellar Clouds: Further Evidence for Carbon Nanoparticles

The excitation of photoluminescence (PL) and infrared emission from carbon nanoparticles by the absorption of photons from the interstellar radiation field is discussed using a model based on energy conservation. It is shown that the partitioning of energy between PL and internal excitation can be used to constrain the type and size of particles responsible for the extended red emission (ERE) and to relate these particles to sources of the aromatic infrared (AIR) emission features. This analysis demonstrates that the ERE (λ ≳ 600 nm) is likely emitted by particles containing ≈50 carbon atoms and that such particles are not strong emitters at 3.3 μm. It is found that only particles that do not have high PL emission efficiency can radiate significantly at 3.3 μm, and, as a result, ERE and 3.3 μm emission will not generally be cospatial. This effect is greatest in low-excitation objects. Application of this model to ERE and AIR emission in the Red Rectangle and elsewhere provides an estimate of PL efficiency that is consistent with that from polycyclic aromatic hydrocarbon and hydrogenated amorphous carbon materials. This efficiency is typically 0.1 but can be much less in regions where the hardness of the UV radiation field is reduced. An analysis of the photochemical processes involved in this conversion shows that ERE will not be produced in objects where Teff ≤ 104 K. Extended emission at longer wavelength is discussed, and it is suggested that this occurs from carbon nanoparticles with more than 50 atoms. In particular, long-wavelength bands at 1.15 and 1.5 μm detected by Gordon and coworkers are consistent with PL emission from carbon nanoparticles having ≈70 and ≈120 carbon atoms, respectively. These quantitative results provide further support for the presence of carbon nanoparticles in the interstellar medium and their assignment as the source of the extended red and AIR emissions as well as the 217.5 nm absorption band.
Simultaneous Retrieval of Parameters in a Transient Conduction-Radiation Problem Using a Differential Evolution Algorithm

This article deals with the application of the differential evolution (DE) algorithm for the inverse analysis of a transient conduction-radiation heat transfer problem. Thermophysical properties and/or optical properties of the medium are simultaneously retrieved with a known temperature field. The conducting-radiating planar enclosed medium bounded by diffuse-gray boundaries is absorbing, emitting, and scattering. In both the direct and inverse methods, the energy equations are solved using the lattice Boltzmann method (LBM), and the finite volume method (FVM) is used to compute the radiative information. In the inverse method, the objective function is minimized using the DE algorithm. Any two sets of parameters, viz., the extinction coefficient, the scattering albedo, emissivity and conduction-radiation parameter, are simultaneously retrieved. The effects of key DE algorithm parameters, such as the weighting factor and the crossover constant on the quality of solutions, are studied. Measurement errors are accounted. The accuracy of the DE algorithm is compared with the genetic algorithm. The DE algorithm is significantly faster, and it yields the global optimum for a wide range of parameters.
Scaling behavior for gravity induced flow of a yield stress material

Deformation of a cylinder of yield stress material under gravitational loading is investigated numerically, and found to obey a geometric scaling law that is independent of both the magnitude of deformation and yield stress. This scaling law provides a fundamental connection between the initial and final dimensions of the body, and the critical aspect ratio (radius/height) for the onset of flow. Importantly, this finding is contrary to the standard model of [Murata, Mater. Constr. (Paris) 17, 117–129 (1984); Pashias et al., J. Rheol. 40, 1179–1189 (1996)], which is currently used in industrial processes to measure the yield stress, and predicts that the deformation is independent of radius. Consequently, the accuracy of the latter model is assessed, and a new formalism for such yield stress measurements proposed.
ODE Discretization Schemes as Optimization Algorithms

Motivated by the recent trend in works that study optimization algorithms from the point of view of dynamical systems and control, we seek to understand how to best systematically discretize a given generic continuous-time analogue of a gradient-based optimization algorithm, represented by ordinary differential equations (ODEs). To this end, we show how a suboptimality bound for such continuous-time algorithms can be combined with an ODE solver’s accuracy bound in order to provide non-asymptotic suboptimality bounds upon discretization. In particular, we show that subexponential, exponential, and finite-time convergence rates in continuous time can be nearly matched upon discretization by merely using off-the-shelf ODE solvers of modestly high order. We then illustrate our findings on a modified version of the celebrated second-order ODE that models Nesterov’s accelerated gradient. Lastly, we apply our approach on the rescaled gradient flow.
Luminescence and microstructure of Sm2+ ions reduced by x-ray irradiation in Li2O–SrO–B2O3 glass

Sm3+-doped Li2O–SrO–B2O3 glass sample was prepared by the conventional melt quenching method in air atmosphere. Sm2+ ions in this borate glass were obtained by x-ray irradiation reduction method. The as-prepared and x-ray-irradiated samples were investigated by photoluminescence spectrum and decay curve measurements. The dependence of Sm2+ luminescence intensity on the x-ray irradiation time was investigated. It is found that the conversion of Sm3+→Sm2+ after x-ray irradiation is efficient in this borate glass. Photostability of Sm2+ ions was evaluated by the photobleaching method. Furthermore, the induced optical absorption spectrum measurement after x-ray irradiation was performed. Thermoluminescence above room temperature was also studied after x-ray irradiation. The different kinds of defect structures and the reduction mechanism of Sm2+ ions in this borate glass were discussed. The microstructure of Sm ions in the Li2O–SrO–B2O3 glass was suggested. The proposed microstructure would be helpful to unde.
Can envelope recovery account for speech recognition based on temporal fine structure

Over the past decade, several studies have demonstrated that normal-hearing listeners can achieve high levels of speech recognition when presented with only the temporal fine structure (TFS) of speech stimuli. Initial suggestions to explain these findings were that they were the result of the auditory system’s ability to recover envelope information from the TFS (envelope recovery; ER). A number of studies have since showed decreasing ER with increasing numbers of analysis filters (the filters used to decompose the signal) while intelligibility from speech-TFS remains almost unaffected. Accordingly, it is now assumed that speech information is present in the TFS. A recent psychophysical study, however, showed that envelope information remains in the TFS after decomposition, suggesting a possible role of ER in speech-TFS understanding. The present study investigated this potential role. In contrast to previous work, a clear influence of analysis filter bandwidth on speech-TFS understanding was established.
Decoherence-induced conductivity in the one-dimensional Anderson model

We study the effect of decoherence on the electron transport in the one-dimensional Anderson model by means of a statistical model [1, 2, 3, 4, 5]. In this model decoherence bonds are randomly distributed within the system, at which the electron phase is randomized completely. Afterwards, the transport quantity of interest (e.g. resistance or conductance) is ensemble averaged over the decoherence configurations. Averaging the resistance of the sample, the calculation can be performed analytically. In the thermodynamic limit, we find a decoherence-driven transition from the quantum-coherent localized regime to the Ohmic regime at a critical decoherence density, which is determined by the second-order generalized Lyapunov exponent (GLE) [4].
A Nonlinear Model of the Term Structure of Interest Rates

We present an economically motivated two–factor term structure model that generalizes existing stochastic mean term structure models. By allowing a certain parameter to acquire dynamical behavior we extend the two–factor model to obtain a nonlinear three–factor model that is shown, in a deterministic version, to be equivalent to the Lorenz system of differential equations. With reasonable parameter values the model exhibits chaotic behavior. It successfully emulates certain properties of interest rates including cyclical behavior on a business cycle time scale. Estimation and pricing issues are discussed. Standard PCA techniques used to estimate HJM type models are observed to be equivalent to dimensional estimates commonly applied to ‘spatial data’ in nonlinear systems analysis.
Stellar production as a source of /sup 3/He in the interstellar medium. [abundance]

Low-mass stars produce substantial amounts of /sup 3/He which is mixed into the convective envelope when the stars become giants. There is strong evidence that a large fraction of this envelope is lost from these stars, thus enriching the interstellar medium (ISM) in /sup 3/He.Analytic formulae are presented for the production of /sup 3/He as a function of stellar mass so that our results can be incorporated into numerical models of galactic evolution. Simple estimates suggest that the present interstellar /sup 3/He abundance could be much greater than the quoted protosolar value, perhaps in conflict with the observations.It seem unlikely that /sup 3/He can be used to supplement the cosmological information available from deuterium. Badly needed new observations of interstellar /sup 3/He could provide a valuable check on the theory of the evolution of loss-mass stars. (AIP)
Central limit theorems for the number of records in discrete models

Consider a sequence (X n ) of independent and identically distributed random variables taking nonnegative integer values, and call X n a record if X n > max{X 1,…,X n−1}. By means of martingale arguments it is shown that the counting process of records among the first n observations, suitably centered and scaled, is asymptotically normally distributed.
Hail Growth in an Oklahoma Multicell Storm

Abstract Hail growth in an Oklahoma multicellular storm is studied using a numerical model of hailstone growth and decay and dual-Doppler derived wind fields. Hail was collected at the time of the Doppler radar data collection which provided input for computation of the modeled trajectories. A unique feature of this investigation is the subsequent comparison of model hail trajectories with deuterium derived trajectories obtained from the hail samples. Formation of large hail is found to be almost entirely due to injection of embryos into the major storm updraft from the upwind side, with subsequent growth occurring during repeated vertical excursions through the prime growth layer between 7 and 8 km. Primary embryo source regions are a feeder cell and the precipitation debris region between the feeder and main cells. Qualitative comparisons between observed and modeled hailstones falling near the collection site reveal strong similarities, particularly with respect to ambient temperature during ice format.
Species abundance and diversity index estimation in point transect sampling using composite approach

A composite approach to point transect sampling is adopted in which the properties of the abundance estimator stem from the scheme performed to select points on the study area as well as from the modelled probabilities of detection. A consistent and asymptotically normal estimator of abundance is derived under some assumptions about the detection function, while a multivariate generalization of this result is provided in multi‐species surveys to estimate the species abundance vector. Jackknife estimators of diversity indices are also derived as functions of species abundance estimators. An application is considered for comparing the ecological diversity of avian communities in short rotation forestry versus traditional crops. Copyright © 2011 John Wiley & Sons, Ltd.
Exploring the Trade-offs to Train Robust Neural Models

Adversarial training aims at generating and introducing adversarial examples while training a DNN model and it is one of the few defenses against adversarial attacks. Unfortunately, creating strong adversarial examples comes with an extremely large cost that makes adversarial training techniques impractical on large-scale and distributed models and problems. Therefore, in this survey, I first revisit the state-of-the-art in training robust models and adversarial training, second explore and investigate the different trade-offs found during training (e.g., standard accuracy, adversarial accuracy, training and inference time, time to generate perturbations, and the ratio of cleaned and perturbed inputs while training), and at last discuss how (or if) these techniques can be leveraged in real systems in production. This survey presents some of the results obtained to explore the trade-offs and conclude that although adversarial training is one of the best defenses against adversarial and targeted attacks, its high cost hinders its adoption by the industry.
Coordinated optical and ultraviolet observations of DH Leo

Results are reported from contemporaneous KPNO optical spectroscopy, IUE UV spectroscopy, and KPNO R photometry of the DH Leo triple system in spring 1987. The data are presented in tables, graphs, and spectral phase images and discussed in detail. The H-alpha, H-beta, H-gamma, H-delta, and Ca II H and IRT lines are found to have excess emission, and the phase modulation in H-alpha, H-beta, and Ca II is well correlated with the photometric modulation. This result is attributed to the combination of (1) a small amount of global chromospheric emission and (2) emission from plagelike regions associated with cool starspots. The (H-alpha)/(H-beta) ratio is found to be significantly lower than that in longer-period RS CVn systems. 22 refs.
A Simple Proof of Stability on the Center Manifold for Hopf Bifurcation

A simple proof is presented for the generic case of a well-known fact about Hopf bifurcation: if the loss of stability of an equilibrium point results in periodic solutions via Hopf bifurcation, then the stability of these periodic solutions is determined by their stability on an associated center manifold. More precisely, it is shown that the characteristic exponent determining the stability of the periodic solutions is the same whether computed for the original system or the system restricted to the center manifold. Attention is focused on the finite-dimensional case of a one-parameter family of ordinary differential equations. The proof consists of exhibiting a similarity transformation which uncovers the relationship between the linearized flow of the original system and that of its restriction to the center manifold.
Mid-Infrared Images of the Circumstellar Dust around α Scorpii

We present the first two-dimensional mid-infrared images of the circumstellar dust distribution around the supergiant star α Scorpii. Our observations were made at wavelengths of 12.5 and 20.8 μm using the MIRLIN focal-plane array camera on the Keck II 10 m telescope, with spatial resolution (λ/D) of 0. ″29 and 0. ″48 at the two wavelengths, respectively. Our deconvolved images, which provide a resolution enhancement of approximately a factor of 2, show that the dust shell previously detected in one-dimensional scans is actually highly nonuniform. Specifically, the shell is now seen to be concentrated largely into three discrete clumps, and there is evidence of a more recent ejection which has left a central concentration of dust within about 0. ″3 from the star.
New Device for Skin-Friction Measurement in Three-Dimensional Flows

References 1 Lurie, H. , "Lateral Vibrations as related to Structural Stability," Journal of Applied Mechanics, Vol. 19, 1952, pp. 195-204. 2 Temple, G. and Bickley, W. G. , Rayleigh's Principle, Oxford University Press, London, 1933. 3 Singa Rao, K. and Amba-Rao, C. L. , "Lateral Vibration and Stability Relationship of Elastically Restrained Circular Plates," AIAA Journal, Vol. 10, No. 12, Dec. 1972, pp. 1689-1690. 4 Singa Rao, K. and Amba-Rao, C. L. , "Comment on 'Lateral Vibration and Stability Relationship of Elastically Restrained Circular Plates'," AIAA Journal, Vol. 11, No. 7, July 1973, p. 1056. 5 Flax, A. H. , "Comment on 'Lateral Vibration and Stability Relationship of Elastically Restrained Circular Plates'," AIAA Journal, Vol. 11, No. 11, Nov. 1973, pp. 1599-1600.
a Thoughtful Study of Lorentz Transformations by Clifford Algebras

We give a thoughtful presentation of proper orthocronous Lorentz transformations using the space-time (ℝ1,3) and the Pauli (ℝ3,0) algebras. We present in a closed finite form, a generic written as the exponential of elements of the associated Lie Algebra, together with a physical interpretation of the parameters. We call the result obtained the master equation and it is used to study several important topics of Special Relativity, e.g. exact product of two boosts and the Thomas precession. We also derive other results necessary for a dynamic interpretation of Lorentz transformations.
The 'second maximum’ of the shower transition curve of cosmic radiation

Various observers have reported, besides the well-established first maximum of the Rossi transition curve, a second maximum for larger thicknesses of absorbers. In the present paper, measurements of the Rossi curve, carried out with various counter systems, are reported. None of these measurements shows any indication of a second maximum. Using, however, an arrangement similar to that by Schmeiser & Bothe, a spurious maximum can be obtained under certain circumstances.
Fluidically Enhanced Chevrons for Supersonic Jet Noise Reduction

An experimental and computational investigation of a combination of fluidic injection and chevrons (fluidically enhanced chevrons) for supersonic jet noise reduction was performed. Previous studies have shown that chevrons underperform in overexpanded flow due to reductions in effective penetration. Consequently, this study focuses on improvements gained by fluidic enhancement in the overexpanded regime. Acoustic results indicated the fluidically enhanced chevrons outperform the chevrons, with additional overall sound pressure level reductions of 2 dB in the upstream direction and nearly 1.5 dB in the downstream direction. Spectral results indicated that primary benefits were in shock and low-frequency noise. A small high-frequency penalty was the only observed detriment. Time-averaged velocity and turbulence quantities as well as shock cell spacing, were computed by large-eddy simulation and then compared to particle imaging velocimetry and shadowgraph results. These flowfield measurements indicated that.
Pulsar Nebulae in Supernovae

Pulsars are expected to be born inside Type II supernovae, and the nebulae generated by their spin-down power thus initially interact with the expanding supernova gas. The hydrodynamic interaction can be described analytically while the pulsar is in a constant power output phase if the surrounding density profile is a power law in radius. The power generated by the shock front driven into the supernova gas is about 1.5% of the pulsar power, and, for typical parameters, the shock wave remains in a radiative phase for at least hundreds of years
Schottky-contact plasmonic rectenna for biosensing

We propose a plasmonic gold nanodipole array on silicon, forming a Schottky contact thereon, and covered by water. The behavior of this array under normal excitation has been extensively investigated. Trends have been found and confirmed by identification of the mode propagating in nanodipoles and its properties. This device can be used to detect infrared radiation below the bandgap energy of the substrate via internal photoelectric effect (IPE). Also we estimate its responsivity and detection limit. Finally, we assess the potential of the structure for bulk and surface (bio) chemical sensing. Based on modal results an analytical model has been proposed to estimate the sensitivity of the device. Results show a good agreement between numerical and analytical interpretations.
Effects of algebraic singularities on the voltage dynamics of differential‐algebraic power system model

Voltage stability analysis of differential-algebraic equation (DAE) power system model is more complicated than for systems described by ordinary differential equations (ODEs). In addition to unstable equilibria, algebraic singularity plays a crucial role in assessing the voltage stability. This paper explores the algebraic structure and singularities of the DAE model to investigate its influence on the voltage stability. Singular points are identified at various load levels and are illustrated together with the equilibria using nose curves. Then, at a given load level, the constraint manifold is decomposed into the voltage casual regions and singular points connecting them. Time-domain simulations initiated in the vicinity of singular points are performed to determine how singular points affect system dynamics. It is shown that depending on the relative location of initial points with respect to singular points, trajectories of bus voltages may settle to an infeasible low voltage stable equilibrium point, which may cause a further disturbance in the system leading a voltage stability problem. Copyright © 2007 John Wiley & Sons, Ltd.
Growth Mode of Ice Crystals in Natural Clouds

Abstract The growth mode of ice crystals in natural clouds has been studied by examination of replicas of more than 10,000 crystals sampled in about 120 clouds over the temperature range −2 to −32C. The relationship between the basic ice crystal form deduced from the shape of recently formed small ice crystals and the temperature at which they have grown is found to agree well with the results of laboratory experiments. Within each category of basic crystal form, there is some characteristic and systematic variation in the ratio of crystal axes which depends strongly upon the growth temperature. The growth of an ice crystal along either the a or c axes almost ceases after it reaches a certain length which depends upon the growth temperature. For columnar ice crystals, the ratio of the length of the c axis to the a axis at a given column length has a maximum value at about −5C. For plane ice crystals, the ratio of diameter to thickness for a given diameter has a maximum value at about −15C. Some considerat.
State-of-the-art mass determination of 28Si spheres for the Avogadro project

For a new determination of the Avogadro constant to play a role in the future redefinition and realization of the mass unit, the mass measurements involved need to be carried out at a very high level of accuracy. From a mass comparison among two 1 kg 28Si spheres and the 1 kg platinum–iridium (Pt/Ir) mass standards, the mass of the spheres must be determined with a combined standard uncertainty of less than 5 µg. The BIPM, the PTB and the NMIJ have carried out such a state-of-the-art mass comparison in air and under vacuum in order to reach this target set by the International Avogadro Coordination (IAC). The results obtained for the spheres AVO28-S5 and AVO28-S8 involved in the comparison have demonstrated that by using air buoyancy artefacts and sorption artefacts it is possible to achieve a relative uncertainty of 4.1 × 10−9. The reference value for each sphere has been determined, taking into account the traceability of the masses to the International Prototype of the kilogram, , in due consideration of the correlations among 17 standards used directly or indirectly in this comparison.