Miracle-dz/UniFAR-FTUs huggingface dataset:
Effect of Annealing on Thermoelectric Properties of Bismuth Telluride Compounds

The thermoelectric properties of the p-type (Bi0.25Sb0.75)2Te3 doped with 3 wt% excess Te and the n-type Bi2(Te0.94Se0.06)3 doped substantially with 0.07 wt% I and 0.02 wt% Te which were grown by the Bridgman method at a rate of 6 cm/h were measured before and after annealing, where the annealing was done in the temperature range from 473 up to 673 K for 1–10 h in vacuum and in a hydrogen stream. When annealing was done at 673 K for 2 h in vacuum, the power factor at 298 K for the p-type specimen increased by 35% from 4.25×10-3 to 5.72×10-3 W/mK2. In contrast, when annealing was done at 673 K for 5 h in a hydrogen stream, the power factor at 298 K for the n-type specimen increased by 24% from 4.82×10-3 to 5.99×10-3 K-1. The thermal conductivities κ at 298 K for both annealed specimens then decreased by about 5%. As a result, the maximum thermoelectric figures of merit Z at 298 K for the annealed p- and n-type specimens reached surprisingly large values of 4.16×10-3 K-1 and 3.99×10-3 K-1, respectively, with corresponding ZT values of 1.26 and 1.19. The reason that the Z values of bismuth telluride compounds were significantly enhanced by such an annealing is also discussed.
Comparative structural and electrical analysis of NiO and Ti doped NiO as materials for resistance random access memory

In order to investigate the mechanism behind bistable resistance switching in NiO thin films, we have done detailed x-ray photon spectroscopy (XPS) and x-ray diffraction Analysis (XRD) on NiO and Ti doped NiO samples fabricated under various conditions. We discovered that a high initial resistivity was required for samples to undergo bistable resistance switching, and the presence of metallic Ni content in these samples was determined by XPS. XRD data also showed that NiO grown with a relative (200) orientation was preferred over those grown with relative (111) orientation.
The growth of magnetic fields prior to galaxy formation

Hydromagnetic dynamo theory is applied to the problem of magnetic field amplification in the epoch after recombination but prior to galaxy formation. Large-scale density fluctuations acquire angular momentum from tidal torques exerted by neighboring fluctuations, and small-scale subfluctuations possess helicity due to the Coriolis forces associated with the rotation of the large-scale host fluctuations. Cosmic expansion and the interaction of matter with the ambient radiation field are taken into account. Despite many uncertainties, it is concluded that significant dynamo amplification may have occurred. 15 references.
Stimulated Raman scattering microscopy by spectral focussing and fiber-generated soliton as Stokes pulse

We demonstrate stimulated-Raman and coherent anti-Stokes Raman scattering microscopy with broadband pump and Stokes pulses, using spectral focussing to attain spectral resolution and to rapidly acquire spectra within a spectral window determined by the bandwith of the pulses. As Stokes pulse, we use the redshifted soliton generated in a photonic-crystal fiber which allows for simple shifting of the accessible spectral window. We analyze the requirements that the redshifted soliton imposes on the choice of chirp.
Evaluating Feature Extractors and Dimension Reduction Methods for Near Infrared Face Recognition Systems

This study evaluates the performance of global and local feature extractors as well as dimension reduction methods in NIR domain. Zernike moments (ZMs), Independent Component Analysis (ICA), Radon Transform + Discrete Cosine Transform (RDCT), Radon Transform + Discrete Wavelet Transform (RDWT) are employed as global feature extractors and Local Binary Pattern (LBP), Gabor Wavelets (GW), Discrete Wavelet Transform (DWT) and Undecimated Discrete Wavelet Transform (UDWT) are used as local feature extractors. For evaluation of dimension reduction methods Principal Component Analysis (PCA), Kernel Principal Component Analysis (KPCA), Linear Discriminant Analysis + Principal Component Analysis (Fisherface), Kernel Fisher Discriminant Analysis (KFD) and Spectral Regression Discriminant Analysis (SRDA) are used. Experiments conducted on CASIA NIR database and PolyU-NIRFD database indicate that ZMs as a global feature extractor, UDWT as a local feature extractor and SRDA as a dimension reduction method have superior overall performance compared to some other methods in the presence of facial expressions, eyeglasses, head rotation, image noise and misalignments.
Resonant Magneto-optic Spectra of theb1Σ+g–X3Σ−gTransition of Oxygen Molecules

Abstract We investigated the resonant magneto-optic spectra of the electronic band b 1 Σ + g – X 3 Σ − g of the oxygen molecule. The theoretical analysis was made on the basis of the Zeeman effect of the magnetic-dipole transition. The oxygen molecules were assumed to be subjected to an externally applied magnetic field, which was oriented in a direction longitudinal (the Faraday configuration) or transverse (the Voigt configuration) to the optical path. The polarization change caused by the magnetically induced optical anisotropy of the oxygen molecule was calculated as a function of the frequency and the ellipticity of the incident light and the orientation of the polarization analyzer. Experiments were carried out in the Voigt configuration, using a tunable titanium-doped sapphire laser as a light source. The observed profiles of the Voigt-effect signal for the rotational lines of the various branches agreed with theoretical predictions.
Adaptive complex unscented Kalman filter for frequency estimation of time-varying signals

A simple and robust non-linear filter algorithm has been proposed in this study for estimating the frequency of a time-varying sinusoidal signal under high noise conditions. The real signal is first converted to an analytical signal and its complex state-space model is derived. An unscented complex Kalman filter (CUKF) is then obtained using the complex signal model and the error covariances along with the Kalman gain are updated iteratively. Also, the stability and the convergence characteristics of the proposed filter are presented for a single sinusoid embedded in noise. It has been shown that the proposed algorithm works efficiently for the estimation of abrupt changes in signal frequency under high noise conditions. To evaluate the performance of the proposed algorithm several computer simulation results of real-time and synthetic signals are presented. Further to improve the performance of the proposed filter in the presence of significant noise and distortions, the covariance matrices are tuned iteratively.
Risk-Sensitive Control on an Infinite Time Horizon

Stochastic control problems on an infinite time horizon with exponential cost criteria are considered. The Donsker--Varadhan large deviation rate is used as a criterion to be optimized. The optimum rate is characterized as the value of an associated stochastic differential game, with an ergodic (expected average cost per unit time) cost criterion. If we take a small-noise limit, a deterministic differential game with average cost per unit time cost criterion is obtained. This differential game is related to robust control of nonlinear systems.
A Robust Image Perceptual Hashing Scheme Based on Improved Normalization Algorithm

An improved image normalization algorithm is proposed firstly. Then a geometric robust image perceptual hashing scheme is proposed based on image normalization and discrete cosine transform. The original image is preprocessed using our improved image normalization method. And the selected DCT coefficients as image feature are encrypted for security. The geometric robust image hash is achieved by quantizing encrypted DCT coefficients and coding. The experimental results show that the algorithm can resist against common global affine transformations such as rotation, scaling, translation and their combinations.
Seeking efficient data augmentation schemes via conditional and marginal augmentation

Data augmentation, sometimes known as the method of auxiliary variables, is a powerful tool for constructing optimisation and simulation algorithms. In the context of optimisation, Meng & van Dyk (1997, 1998) reported several successes of the 'working parameter' approach for constructing efficient data-augmentation schemes for fast and simple EM-type algorithms. This paper investigates the use of working parameters in the context of Markov chain Monte Carlo, in particular in the context of Tanner & Wong's (1987) data augmentation algorithm, via a theoretical study of two working-parameter approaches, the conditional augmentation approach and the marginal augmentation approach. Posterior sampling under the univariate t model is used as a running example, which particularly illustrates how the marginal augmentation approach obtains a fast-mixing positive recurrent Markov chain by first constructing a nonpositive recurrent Markov chain in a larger space.
Note on the symmetries of certain material tensors for a particle in Stokes flow

Consider a single rigid particle of arbitrary shape moving in a viscous fluid. A given point 0 of the body has velocity u and the angular velocity of the body is o. The undisturbed flow far from the particle is a uniform velocity U together with a general linear flow composed of a vorticity 2S2 and a pure strain E. The particle exerts on the fluid a force F, and a couple L and a stresslet S specified relative to 0. The stresslet is a second-order tensor defined by Batchelor (1970, p. 562) as the symmetric part of the force dipole strength for the particle and is the particle contribution to the symmetric part of the bulk stress tensor. It should be noted that the values of the translational velocity, the couple and the stresslet will depend on the arbitrary choice of the point 0 of the body. Let the motion be sufficiently slow for the creeping flow equations to be obeyed (low Reynolds numbers). Then from the linearity of the governing equations and boundary conditions F, L and S must each be linear in U u, S2 w and E. At first sight an expression of these relationships might appear to require nine different material tensors of various ranks which all depend on the particle’s shape orientation and the position of the point 0: ($=pk’ A P’ R”. Q’ :). (%E:).
Parallel Array Processors for Digital Image Processing

A major drawback of digital computer image processing is the large computation time required. On the other hand, its flexibility, programmability and computational accuracy make it desirable to use digital processing. Advances in technology of LSI circuitry have now made it possible to increase strongly the computational power of image processing systems by combining many ‘micro computers’ or processing elements to array processors. We discuss several concepts of connecting such small computers and integrating them into a system, and then concentrate on the ‘PEAC’ structure which was closely investigated at PFH. Its application to various image-processing methods such as point operations, neighbourhood operations, guided boundary detection using prior knowledge, and object reconstruction from projections are discussed. In almost all applications a speed-up ratio of k can be achieved, where k is the number of processing elements.
Microwave heating of conductive powder materials

In recent years, a considerable interest has been drawn to microwave heating of powder metals and other electrically conductive materials. In this paper a consistent formulation describing the absorption of microwaves in electrically conductive materials under different microwave heating conditions is developed. A special case when conductive powder particles are surrounded by insulating oxide layers is investigated in detail using the effective-medium approximation. The conditions giving rise to skin effect governed, volumetric, and localized microwave heating are analyzed. Experimental observations of different microwave heating regimes in silicon, iron, and copper powder compacts are in general agreement with the theoretical model.
Polarization in massive X-ray binaries. I - A low-inclination model for Cygnus X-1

The possibility that variable linear polarization in massive X-ray binaries is produced by electron scattering in an asymmetric stellar wind is investigated. The stellar wind is asymmetric because of the gravitational field of the secondary (X-ray source). The degree of asymmetry and the magnitude of the linear polarization are controlled by the degree to which the primary star fills its Roche lobe. For the well-observed X-ray binary Cyg X-1, the present model can produce the correct magnitude for the polarization. Provided that the inclination of the system is less than about 20 deg, the present model should also predict the correct phase dependence of the polarization. Modifications to the model are described which would enable it to apply to systems with higher inclination.
Limits on the space density of double degenerates as type Ia supernova progenitors

A search for variable radial velocities in 25 hot white dwarfs yielded no binaries with orbital periods between 3 and 10 hr. The fraction of all white dwarfs with spectral classes DA1 to DA5 that are binary with periods in this range is less than or equal to 0.12, with 90 percent confidence. A simple model to predict the merger rate of binary degenerates, based on the observations presented on the observed luminosity function of white dwarfs, on assumptions about the distribution of initial binary periods, and on estimates of the fraction of all white dwarf pairs whose combined mass exceeds the Chandrasekhar limit. The upper limits so derived are less than the observed rate of Galactic Type Ia supernovae. 24 refs.
Josephson junctions with nearly superconducting metal silicide barriers

We present a detailed study of the electrical properties of Nb-based planar Josephson junctions with superconducting metal silicide barriers, TiSi2 and WSi2. While these nonhysteretic junctions are useful for voltage standard applications, they are also an excellent model system to study proximity coupling in junctions having a barrier with a finite superconducting transition temperature. These silicide-barrier junctions have excellent uniformity and controllability, but as opposed to junction barriers with no measurable superconducting transition, the critical current of these superconducting-barrier junctions is a strong function of the operating temperature near 4 K; we also discuss the impact of this temperature dependence on device applications.
A dielectric study of the X/65/35 lanthanum-modified lead zirconate-titanate series

Abstract The occurrence (or not) of a ferroelectric phase transition and the field induced ferroelectric to relaxor states transition has been studied through dielectric susceptibility and pyroelectric current experiments in the x/65/35 PLZT series (x=5 to 12). The results are qualitatively interpreted using random field theory principles.
Ultrathin transition-metal oxide films: Thickness dependence of the electronic structure and local geometry in MnO

Ultrathin manganese monoxide films on silver substrates are studied as a function of the thickness using x-ray absorption spectroscopy and x-ray photoemission spectroscopy. By combining these techniques, an improved understanding of both the local geometry and the electronic structure is achieved. It was found that both electronic and geometric properties in ultrathin films differ significantly from the bulk. A tetragonal distortion of the oxide films is revealed by polarization-dependent x-ray absorption measurements; the extent is decreasing gradually with increasing film thickness. A relaxation of an epitaxial oxide layer induced by heating also leads to a decrease of the tetragonal interface strain. The electronic structure of ultrathin manganese oxide films changes in the valence-band region with dependence on thickness.
A Study of a Stable AlCuFe Quasicrystal in Solid and Liquid State

A stable Al65Cu20Fe15 quasicrystal with an icosahedral structure is studied in solid and liquid state. It is found that the icosahedral phase in Al65Cu20Fe15 alloy does not grow.directly from the pure liquid state, but rather forms between monoclinic Al13Fe4 and residual liquid state at 865-degrees-C. The melting point of the Al65Cu20Fe15 icosahedral quasicrystal occurs at 865-degrees-C and that of the A165Cu20Fe15 alloy occurs at 1008-degrees-C. Moreover, the monoclinic Al13Fe4 is transformed into the icosahedral phase easily at the temperature of 845-degrees-C. The icosahedral quasicrystal in Al65Cu20Fe15 alloy has a high thermal stability even at 950-degrees-C. Above 950-degrees-C, the icosahedral structure tends to an amorphous structure.
The Bohm–Chodura plasma sheath criterion

The ion flow velocity entering the Debye sheath is constrained to satisfy the Bohm criterion: velocity must be equal to or greater than sonic. The ion flow velocity entering the magnetic presheath (which arises upstream of the Debye sheath when a magnetic field, oblique to the solid surface is present) is constrained to satisfy the Chodura criterion: velocity‐parallel to B must be equal to or greater than sonic. The Bohm criterion, in its marginal form where v=cs, is associated with a ‘‘gentle entry’’ into the sheath with Δne=Δni, while v≳cs corresponds to ‖Δne‖≳‖Δni‖. The magnetic presheath, in contrast with the Debye sheath, is a region of quasineutrality, and thus only Δne=Δni is permitted. This might appear to prohibit supersonic flow parallel to B at the entrance to the magnetic presheath, which the analysis of Chodura and Riemann has found to be permitted, in fact. This apparent contradiction is resolved by analyzing the magnetic presheath region to bring out more explicitly the role played by inert.
Electron pitch angle distributions throughout the magnetosphere as observed on Ogo 5.

A survey of the equatorial pitch angle distributions of energetic electrons is provided for all local times out to radial distances of 20 RE on the night side of the earth and to the magnetopause on the day side of the earth. In much of the inner magnetosphere and in the outer magnetosphere on the day side of the earth, the normal loss cone distribution prevails. The effects of drift shell splitting (that is, the appearance of pitch angle distributions with minimums at 90°, called butterfly distributions) become apparent in the early afternoon magnetosphere at extended distances, and the distribution is observed in to 5.5 RE in the nighttime magnetosphere. Inside ∼9 RE the pitch angle effects are quite energy dependent. Beyond ∼9 RE in the premidnight magnetosphere during quiet times the butterfly distribution is often observed with j⊥/j∥ < 1/100. It is shown that these electrons cannot survive a drift to dawn without being considerably modified. The role of substorm activity in modifying these distributions is identified.
Design of hybrid refractive-diffractive visible lens with small F-number

A hybrid diffractive/refractive visible lens with small F-number of 1.5 is proposed based on the special chromatic aberration of diffractive optical element. It is used in the optical system of visible camera for space debris.The visible lens has an effective focal length of 100 mm, a working wavelength range of 0.5-0. 8μm and a field of view 6°. Firstly,the lens system consists of three groups and five lenses.Then, aspheric and diffractive surfaces are used in order to correct high-order aberrations resulting from large relative aperture.Finally, the lens is designed with the help of Code-v optical design software.The lens is evaluated by energy concentration, the dispersion spot diameter, lateral color, distortion,the simulated final design shows adequate image quality. The method puts forward a new ideas for visible camera for space debris optical system design and had an important reference significance and application value.
Detector for spatial and temporal imaging of single photons

A photon detector with spatial and temporal resolution capabilities is described. The detector consists of an image intensifier and a position-sensitive photomultiplier tube. It has 2.5×103 resolvable pixels, a dark count rate of 5×10−2 pixel−1 s−1, and a quantum efficiency of 12% at 670 nm. The maximum data rate for a pixel is 500 kHz, which is also the limit of the entire detector aperture. The absolute time of a single event can be determined to within 100 ns. The single pixel response was found to be linear with incident intensity for short pulses of light containing up to several thousand photons.
Electrical characteristics of a Dy-doped HfO2 gate dielectric

This letter describes a process for the preparation of high-quality Dy-doped HfO2 for use in gate dielectric applications. Compared with conventional undoped HfO2, the HfO2 gate dielectric which contains an optimum concentration of Dy exhibits the lowest leakage current and minimum effective oxide thickness. The lower electronegativity and larger atomic radii of Dy contribute to the improvement in leakage current for Dy-doped HfO2. The Dy-doped HfO2 is a promising gate dielectric layer for use in future high-k gate dielectric applications.
Thermal stress evaluation in the steel continuous casting process

Two numerical models for the thermal stress and plastic strain analysis in the solid shell at the initial stage of a steel continuous casting process, are presented and their performances evaluated. First, a numerical procedure based on a natural extension of the semi‐analytical study proposed by Weiner and Boley (J. Mech. Phys. Solids 1963; 11:145–154) is introduced and validated by comparison with their semi‐analytical 1‐D solution. The basic hypotheses of this model, and particularly the extended plane strain condition with uniform axial strain, are afterwards tested in more complex and realistic situations by comparing results with those obtained by an alternative numerical scheme presented by Fachinotti (Doctoral Thesis, Universidad Nac. Litoral, Argentina, 2001) and Fachinotti and Cardona (Internal Report, CIMEC, sent to IJNME, 2002). Finally, results of a typical and representative 3D simulation, corresponding to a slab continuous casting process, are shown. Copyright © 2005 John Wiley & Sons, Ltd.
Dynamical instabilities in axisymmetric stellar systems. I - Oblate E6 models

The stability of a set of models based on isothermal oblate E6 elliptical galaxies is studied using N-body techniques. The only stable models are those that are near the isotropic model and have nearly equal number of stars in retrograde and prograde orbits. Fast rotators are unstable to modes that appear to be analogous to the classical streaming instability seen in many disk systems. Systems with a large velocity dispersion in the direction of the cylindrical radius are unstable to modes that appear to be similar to the radial orbit instability observed in some spherical systems. However, evidence is presented that these two instabilities may be related, and an instability criterion that applies to both is constructed. 28 refs.
Universal structures in power ℵ1

Abstract It is consistent with ¬ CH that every universal theory of relational structures with the joint embedding property and amalgamation for -(3)-diagrams has a universal model of cardinality ℵ1. For classes with amalgamation for -(4)-diagrams it is consistent that and there is a universal model of cardinality ℵ2.