Miracle-dz/UniFAR-FTUs huggingface dataset:
Image categorization based on multi-scale vocabulary

Nowadays, local feature based image categorization algorithm has attracted increasing attention in the computer vision community. In this paper, we present a local feature based image categorization scheme by using Multi-Scale Vocabulary. This technique works by partitioning the feature space into clusters at several different levels to form multi-scale vocabulary and generate corresponding fixed-length descriptors at different scales for each image. Then we design particular similarity measure for multi-scale descriptors and finally apply KNN and SVM to realize image categorization task. Experiments conducted on the ETH80 dataset have demonstrated the effectiveness of our approach.
MIXING OF GRANULAR MATERIALS: A TEST-BED DYNAMICAL SYSTEM FOR PATTERN FORMATION

Mixing of granular materials provides fascinating examples of pattern formation and self-organization. More mixing action — for example, increasing the forcing with more vigorous shaking or faster tumbling — does not guarantee a better-mixed final system. This is because granular mixtures of just barely different materials segregate according to density and size; in fact, the very same forcing used to mix may unmix. Self-organization results from two competing effects: chaotic advection or chaotic mixing, as in the case of fluids, and flow-induced segregation, a phenomenon without parallel in fluids. The rich array of behaviors is ideally suited for nonlinear-dynamics-based inspection. Moreover, the interplay with experiments is immediate. In fact, these systems may constitute the simplest example of coexistence between chaos and self-organization that can be studied in the laboratory. We present a concise summary of the necessary theoretical background and central physical ideas accompanied by illustrative experimental results to aid the reader in exploring this fascinating new area.
Idealized Saturn magnetosphere shape and field

We construct an idealized three-dimensional model of Saturn's magnetosphere. The total magnetospheric field is a sum of three contributions; the first two contributions are internal, in the form of a planetary dipole and an equatorial ring current deduced from Voyager observations. We concentrate on the third contribution, resulting from the interaction of the solar wind with the Kronian magnetosphere. From the balance between the solar wind ram pressure and the magnetospheric pressure, we provide simultaneously models of the magnetopause and of the magnetic field due to the surface currents on the magnetopause. The resulting magnetopause has characteristics intermediate between those of analogous Earth and Jupiter magnetospheric models. A natural day-night asymmetry arises in the total magnetospheric field. Its intensity is tested with Voyager 1 data: the third contribution improves the agreement between data and models in the outer magnetosphere. This work extends the range of a physically reliable model of Saturn's magnetosphere in latitudinal and longitudinal directions from regions where there have been observations to regions where there have not. We discuss several possible applications, particularly some relevant to the future Cassini mission.
Norm‐controlled inversion in smooth Banach algebras, II

We show that smoothness implies norm‐controlled inversion: the smoothness of an element a in a Banach algebra with a one‐parameter automorphism group is preserved under inversion, and the norm of the inverse a−1 is controlled by the smoothness of a and by spectral data. In our context smooth subalgebras are obtained with the classical constructions of approximation theory and resemble spaces of differentiable functions, Besov spaces or Bessel potential spaces. To treat ultra‐smoothness, we resort to Dales‐Davie algebras. Furthermore, based on Baskakov's work, we derive explicit norm control estimates for infinite matrices with polynomial off‐diagonal decay. This is a quantitative version of Jaffard's theorem.
Large deviations-based upper bounds on the expected relative length of longest common subsequences

Consider the random variable L n defined as the length of a longest common subsequence of two random strings of length n and whose random characters are independent and identically distributed over a finite alphabet. Chvátal and Sankoff showed that the limit γ=lim n→∞E[L n ]/n is well defined. The exact value of this constant is not known, but various methods for the computation of upper and lower bounds have been discussed in the literature. Even so, high-precision bounds are hard to come by. In this paper we discuss how large deviation theory can be used to derive a consistent sequence of upper bounds, (q m ) m∈ℕ, on γ, and how Monte Carlo simulation can be used in theory to compute estimates, q̂ m , of the q m such that, for given Ξ > 0 and Λ ∈ (0,1), we have P[γ < q̂ < γ + Ξ] ≥ Λ. In other words, with high probability the result is an upper bound that approximates γ to high precision. We establish O((1 − Λ)−1Ξ−(4+ε)) as a theoretical upper bound on the complexity of computing q̂ m to the given level of accuracy and confidence. Finally, we discuss a practical heuristic based on our theoretical approach and discuss its empirical behavior.
Effective spin injection in Au film from Permalloy

The electrical injection of spin current in the lateral Permalloy/Au/Permalloy spin valve devices was investigated. Clear spin valve effects were found in nonlocal spin valve measurements. The spin diffusion length of Au was evaluated to be 168nm. High spin injection polarization of 26% at 15K was achieved from our samples with low interface resistance. The observed spin injection reveals the highest polarization among the reported values. This work demonstrates the high spin injection polarization through clean interface with low interface resistance.
Stability Theory of Synchronized Motion in Coupled-Oscillator Systems. III Mapping Model for Continuous System

By starting with a reaction-diffusion equation a mapping model for the continuous system is proposed. The transition from the uniform state to the non-uniform one occurs at the same value of the diffusion constant for the mapping model as for the original reaction-diffusion equation if the transition exists. The mapping model is further studied by adopting the logistic model in one-dimensional space with a periodic boundary condition. Equal time spectra in wave number space and power spectra for several values of wave numbers are numerically obtained. A comparison of the numerical results of the equal time spectra with a simple theory is made to give a satisfactory agreement for large wave numbers.
ON THE SULFUR AND NITROGEN ABUNDANCES IN THE NUCLEUS OF SEYFERT 2 AND LINER GALAXIES

We study the gas abundance in Seyfert 2 and LINER nuclei using optical emission-line data for a sample of 177 galaxies obtained from the literature. On the basis of photoionization model results it is shown that the range presented by the emission-line ratios [S II]/Hα and [N II]/Hα can only be reproduced by a range in sulfur and nitrogen abundances from half-solar to five times solar. The abundances of these two elements seem to be correlated. It is also shown that, if the apertures are small enough, the observed [S II]/Hα values indicate overabundance of sulfur for most Seyfert 2 and LINER nuclei. A similar result has been previously found for nitrogen.
DEGENERATE ELLIPTIC PSEUDODIFFERENTIAL EQUATIONS OF PRINCIPAL TYPE

This article studies pseudodifferential operators which are elliptic outside an (n - 1)-dimensional submanifold ω of a closed n-dimensional manifold Γ. It is assumed that at those points of the cotangent bundle at which the ellipticity condition is violated the gradient of the determinant of the symbol is nonzero and transversal to ω. On ω a number of boundary conditions are prescribed, and a number of potential operators with unknown densities are adjoined to the original equation; the normal solvability of this boundary value problem is then established. Bibliography: 21 items.
Normality and the numerical range of an operator

For an operator T on a Hubert space H, let W(T) = {(Tx, x) : xÇ£H and \\x\\ = 1} denote the numerical range of T\ and let S(T) designate the convex hull of <T(JH), the spectrum of T. I t is well known, for a normal operator T, that clW(T) =2)( r ) . Our main results are, in a certain sense, converses to this statement. They generalize results of Donoghue [ l ] , Hildebrandt [2], Nieminen [4], Meng [3], Putnam [6], and the author [7].
The Rotation curve of the milky way to 2.5-R(0) from the thickness of the HI layer

A new approach to calculating the H I rotation curve of the outer Milky Way is presented. This method uses the variation with galactic longitude in the angular thickness of the H I layer to solve for the distance to slices through the H I data cube. The derived rotation curve shows excellent agreement with other kinematic constraints if the local galactic constants have values of R0 = 7.9 +/- 0.8 kpc and Theta0 = 200 +/- 10 km/s. This procedure also yields the variation in thickness of the H I layer with radius. If it is assumed that this gas has a constant velocity dispersion, then application of the hydrostatic equilibrium equation implies that the mass density in the plane of the Galaxy drops approximately exponentially with radius with an e-folding length of 0.49 +/- 0.06 R0. Combining this information with the derived rotation curve then allows the construction of a full mass model for the Milky Way.
Global MHD Instabilities in a Three-dimensional Thin-Shell Model of Solar Tachocline

We generalize the linear analysis of the global instability of coexisting differential rotation and toroidal magnetic fields in the solar tachocline to include continuous radial stratification, thermodynamics, and finite tachocline thickness, as perturbed by three-dimensional disturbances of longitudinal wavenumbers m = 1, 2. For radiative tachocline stratification, the instability for both banded and broad toroidal field profiles is similar to the two-dimensional and shallow water cases studied previously, even though the unstable modes have substantial vertical structure. For overshoot tachocline stratification, instability for banded toroidal fields with peaks ≲20 kG is similar to the corresponding shallow water case, but for substantially higher (perhaps unrealistic) toroidal fields there is no low-subadiabaticity cutoff, and modes appear with much higher growth rate and increasingly negative phase velocities in longitude, analogous to those found earlier by Cally. All of these results are only modestly sensitive to the tachocline thickness chosen. For broad toroidal field profiles, the instability results are similar to the two-dimensional and shallow water cases for toroidal field peaks up to at least 80 kG, unless the shell has a thickness that is a substantial fraction of a pressure scale height. For thinner shells, only above about 94 kG do the high growth rate, low phase velocity modes appear, with structure similar to the "polar kink" instability Cally found. But even in this case, we find that the slower growing "clam-shell" instability eventually replaces the faster growing polar kink modes. We conclude that for conditions most likely to occur in the solar tachocline, such as peak toroidal fields limited by the dynamo to 20 kG or less, the two-dimensional and shallow water type unstable modes are likely to predominate even when the tachocline has finite thickness and the modes can have radial structure.
Partitioning Projective Geometries into Caps

In [2] by means of a fairly lengthy argument involving Hermitian varieties it was shown that PG(2n, q 2) can be partitioned into (q 2n++ 1 + 1)/(q + l)-caps. Moreover, these caps were shown to constitute the “large points” of a PG(2n, q) in a natural way. In [3] a similar argument was used to show that once two disjoint (n – l)-subspaces are removed from PG(2n, q 2), the remaining points can be partitioned into (q 2n – 1)/(q 2 – l)-caps. The purpose of this paper is to give a short proof of the results found in [2], and then use the technique developed to partition PG(2n, q) into (qn + l)-caps for n even and q any prime-power. Moreover, these caps can be treated in a natural way as the “large points” of a PG(n – 1, q).
Evaluation of a new quadrilateral thin plate bending element

A review of 4-node, 12 degrees-of-freedom quadrilateral elements for thin plates is presented. A new element called DKQ is discussed. The formulation is based on a generalization of the efficient and reliable triangular element DKT presented in References 1 and 2 and on the rectangular element QC presented in Reference 3. These elements are derived using the so-called discrete Krichhoff technique. A detailed numerical evaluation of the behaviour of the DKQ element for the computation of displacements and stresses for thin plate bending problems is presented and discussed. The DKQ element appears to be a simple and reliable 12 degrees-of-freedom thin plate bending element.
Gas compositional and pressure effects on thermographic phosphor thermometry

In the present study, the influence of gas compositional and pressure conditions on thermographic phosphor thermometry was investigated. A heatable pressurized and optical accessible calibration chamber was built to measure the phosphorescence decay time at different temperatures as well as at different partial and absolute pressures. At room temperature, the absolute pressure could be increased to 30 bar. To vary the gas composition, nitrogen, oxygen, carbon dioxide, methane, helium as well as water vapour were used. Three different phosphors were investigated: Mg4FGeO6:Mn, La2O2S:Eu and Y2O3:Eu. Phosphorescence was excited by the third and the fourth harmonics of a pulsed Nd:YAG-laser (355 nm and 266 nm, respectively) and recorded temporally resolved by a photomultiplier. Mg4FGeO6:Mn as well as La2O2S:Eu were not influenced significantly by varying partial and absolute pressures. In contrast, Y2O3:Eu showed a strong sensitivity on the oxygen concentration of the surrounding gas phase as well as irreversible changes in the phosphorescence decay time after increasing the absolute pressure.
Non-linear diffusion III. Diffusion through isotropic highly elastic solids

A theory is formulated for the diffusion of fluids through highly elastic materials. This forms an extension of earlier work (Adkins 1963a, b) on flows of mixtures of fluids, but attention is here confined to the diffusion of a single fluid through the solid. It is assumed that each point of the region of space concerned may be occupied simultaneously by the fluid and solid, and the motion of each constituent is governed by the usual equations of motion and continuity. The mechanical properties of each substance are specified by means of constitutive equations for the stresses, and diffusion effects by means of a body force or diffusive drag acting on each component, this force being a function of the composition and relative motions of the constituents of the solid-fluid mixture. In applications, attention is confined to steady-state problems. These include the swelling of a solid due to presence of fluid, and the diffusion of a fluid through uniform plane plates or slabs subject to uniform all-round compression or extension and to a shearing deformation. It is assumed throughout that the diffusing fluid is non-Newtonian, the theory for ideal and viscous fluids emerging as special cases.
Energy transfer from fluorescent thin films to metals in near-field optical microscopy: Comparison between time-resolved and intensity measurements

The fluorescence intensity, fluorescence decay time, and shear-force images of a thin film have been simultaneously investigated by reflection scanning near-field optical microscopy using an uncoated fiber tip. The sample is made of a europium chelate embedded in a 32-nm thick polymer layer that coats a periodic structure of gold and chromium. It is contended that the three images carry different and somewhat complementary information; the shear force supplying the sample profile while the intensity mainly depends on the local sample’s reflectance. Moreover, the decay time exhibits the local-energy-transfer process that takes place between the metallic substrate and the dye layer.
Problems in measuring diffuse X-ray scattering

Abstract Problems encountered in making measurements of diffuse X-ray scattering are discussed. These generally arise from the need to measure very weak scattering in the presence of very strong scattering (Bragg peaks) using multi-detectors of various kinds. The problems are not confined to synchrotron experiments but may even occur using a tube source in the home laboratory. Specific details are given of experiments using 80.725 keV X-rays and a mar345 Image Plate detector on the 1-ID beamline of XOR at the Advanced Photon Source. In these a severe ‘blooming’ artefact which occurred around some strong Bragg peaks was traced to fluorescence from a steel mounting plate in the detector when strong Bragg peaks were incident. Algorithms developed to remove these artefacts from the data are described.
Ultrasound techniques for characterizing colloidal dispersions

Interest in the interaction of acoustic waves with particulate mixtures has a long history—dating back to the work of Rayleigh in the 19th century. This interest has intensified over the last fifteen years as advances in electronics and instrumentation science have brought the possibility of using ultrasound to characterize colloidal mixtures both in the laboratory and in-process, and in both of these contexts a small number of instruments are currently in use. The characterization of colloidal mixtures by ultrasound requires a formal theoretical basis which relates the properties of the mixture, particularly the dispersed phase particle size distribution (PSD), to the complex wavenumber governing propagation. The number of theoretical treatments is vast, having evolved over more than a century. This paper is intended to provide a review of these developments in a form which will enable new researchers in the field to climb a very steep learning curve in a relatively short time. We discuss definitions and production techniques for colloidal mixtures and the basic physical phenomena underlying wave propagation through them. We identify two approaches to the propagation problem—scattering and coupled-phase; these are treated both separately and comparatively, particularly in relation to limitations that arise when the concentration of particles is high and the basic theories break down. We introduce the basic method for the measurement of PSD and show how dynamic effects such as flocculation and crystallization can be observed and modelled. The core of all ultrasonic characterization procedures is the physical measurement of the ultrasonic wave attenuation coefficient and phase velocity as functions of frequency; here we discuss these techniques on the basis that what is observable or measurable about a colloid depends on both its physical properties and the frequency bandwidth available for measurement. This paper concludes with our view on future developments of measurement technique and theoretical treatments.
On Two-Dimensional Magnetohydrodynamic Turbulence

Numerical studies of decaying two-dimensional (2D) magnetohydrodynamic (MHD) turbulence are presented. Results concern mainly the decay laws of integral quantities and the scaling properties of spectra and structure functions. The self-similarity of the decay is characterized by the invariance of the ratios of resistive and viscous dissipation rates, kinetic and magnetic energies, and mean parallel and perpendicular velocities. The energy decay rate is primarily determined by the conservation of the mean-square magnetic potential, but the process is somewhat retarded at intermediate times by current density condensation in the magnetic eddies. In contrast to the 3D case, the energy spectrum agrees with the Iroshnikov–Kraichnan (IK) law Ek∼k−3/2, but is modified by a strong anomalous bottleneck effect. Structure functions of the Elsasser fields satisfy the property of extended self-similarity, which provides accurate values of the relative scaling exponents. Also the structure functions themselves show cle.
Linear model reduction and solution of the algebraic Riccati equation by use of the sign function

The sign function of a square matrix can be defined in terms of a contour integral or as the result of an iterated map $. Application of this function enables a matrix to be decomposed into two components whose spectra lie on opposite sides of the imaginary axis. This has application in reduction of linear systems to lower order models and in the solution of the matrix Lyapunov and algebraic Riccati equations.
Validation of a Time- and Frequency-Domain Grazing Flow Acoustic Liner Model

In today's aeroengines, acoustic liners are extensively used to suppress noise. To optimize their placement and tuning, there is a need for acoustic liner models capturing their effect. Traditionally, the presence of a mean flow has been accounted for through the Ingard or later the generalization in form of the Myers boundary condition. This paper shows that a direct use of nominal impedance for the acoustic liner is justified if the mean flow is properly accounted for by the flow equations. An accurate assessment of the acoustic liner in the presence of grazing flows can be obtained without using an acoustic liner model accounting for the flow, for example, the Myers boundary condition. Validations have been made for both time and frequency-domain solvers using large-eddy simulations and linearized Navier-Stokes equations.
Matematik Öğretmeni Adaylarının Matematik Tarihi Dersine İlişkin Düşünceleri

Bu arastirma, matematik ogretmeni adaylarinin Matematik Tarihi dersine iliskin dusuncelerini belirlemek amaciyla gerceklestirilmistir. Arastirmada betimsel tarama modeli kullanilmistir. Arastirmanin calisma grubunu, Eskisehir Osmangazi Universitesi Egitim Fakultesi Ilkogretim Matematik Ogretmenligi lisans programinda ogrenim goren 121 ogretmen adayi olusturmaktadir. Verilerin toplanmasi asamasinda, ogretmen adaylarinin Matematik Tarihi dersinin icerigine ve gerekliligine iliskin dusuncelerini belirlemek icin arastirmaci tarafindan hazirlanmis olan âMatematik Tarihi Dersine Yonelik Gorus Anketiâ ve demografik bilgi formu kullanilmistir. Bununla birlikte ankette yer alan acik uclu soru ile bir ilkogretim matematik ogretmeni adayi olarak Matematik Tarihi dersini almis olmanin ne kazandirdigina iliskin ogretmen adaylarinin dusuncelerinin belirlenmesi amaclanmistir. Toplanan veriler hem nicel hem nitel olarak analiz edilmis olup betimsel istatistikten yararlanilmistir. Arastirmanin sonuclarina gore; ogretmen adaylari bu ders kapsaminda edindikleri bilgilerden en cok sayilar, geometri ve denklem cozme ve en az da vektorler, metrik sistem ve integral konularindaki tarihi gelismeleri ogrenmenin kendilerine yararli oldugunu dusunmektedirler. Ayrica ogretmen adaylarinin matematiksel kavramlarin tarihi gelisimini ve unlu matematikcilerin biyografilerini ogrenmenin kendilerine cok sey kattigini ve bu bilgileri gelecekte matematik derslerinde ogrencileri ile paylasmak istediklerini belirttikleri gorulmektedir.