Miracle-dz/UniFAR-FTUs huggingface dataset:
Image denoising with multiple layer block matching and 3D filtering

Block Matching and 3-D Filtering (BM3D) algorithm is currently considered as one of the most successful denoising algorithms. Despite its excellent results, BM3D still has room for improvements. Image details and sharp edges, such as text in document images are challenging, as they usually do not produce sparse representations under the linear transformations. Various artifacts such as ringing and blurring can be introduced as a result. This paper proposes a Multiple Layer BM3D (MLBM3D) denoising algorithm. The basic idea is to decompose image patches that contain high contrast details into multiple layers, and each layer is then collaboratively filtered separately. The algorithm contains a Basic Estimation step and a Final Estimation step. The first (Basic Estimation) step is identical to the one in BM3D. In the second (Final Estimation) step, image groups are determined to be single-layer or multilayer. A single-layer group is filtered in a same manner as in BM3D. For a multi-layer group, each image patch within the group is decomposed with the three-layer model. All the top layers in the group are stacked and collaboratively filtered. So are the bottom layers. The filtered top and bottom layers are re-assembled to form the estimation of the blocks. The final estimation of the image is obtained by aggregating estimations of all blocks, including both single-layer and multi-layer ones. The proposed algorithm shows excellent results, particularly for the images containing high contrast edges.
Opacities for stellar envelopes

We define stellar envelopes to be those regions of stellar interiors in which atoms exist and are not markedly perturbed by the plasma environment. Availability of accurate and extensive atomic data is a prime requirement for the calculation of envelope opacities. For envelopes we adopt the criterion of mass density ρ≤0.01 g cm −3 . We present radiative Rosseland mean opacities for envelopes obtained using atomic data calculated in an international collaboration referred to as the Opacity Project, or OP. Equations of state are calculated using an occupation-probability formalism. To a good approximation, ionization equilibria and level populations in envelopes depend only on the temperature T and electron density N e and are insensitive to chemical mixtures
Discrepancy of Arithmetic Progressions in Higher Dimensions

Abstract K. F. Roth (1964, Acta. Arith. 9 , 257–260) proved that the discrepancy of arithmetic progressions contained in [1, N ]={1, 2, …, N } is at least cN 1/4 , and later it was proved that this result is sharp. We consider the d -dimensional version of this problem. We give a lower estimate for the discrepancy of arithmetic progressions on [1, N ] d and prove that this result is nearly sharp. We use our results to give an upper estimate for the discrepancy of lines on an N × N lattice, and we also give an estimate for the discrepancy of a related random hypergraph.
Low-temperature in-situ growth of high-coercivity Fe-Pt films

FePt films with high coercivity, large energy product and corrosion resistance, have high potential in applications such as MEMs and ultra-high density magnetic recording. Much attention has been paid to the preparation of high quality films at substrate/annealing temperatures as low as possible to accommodate processing adopted in the manufacture of MEMs or sensors. In this study Fe/sub x/Pt/sub 1-x/ thin films were deposited by DC magnetron sputtering onto Si[100] and CrMo-seeded glass substrates at a substrate temperature (Ts) 30 to 600/spl deg/C with or without further post-annealing. Optimum magnetic properties of our studied films were obtained at the Fe/sub 53/Pt/sub 47/ composition as-deposited at Ts 300/spl deg/C. The in-plane coercivity (Hc) is 8 kOe for as-deposited films on both Si[100] and glass substrates. The films on Si[100] showed a maximum magnetization (M2T) and a maximum energy product of 950 emu/cm/sup 3/ and 15.8 MGOe, respectively. The squareness ratio (M/sub r//M/sub s/) of the as-deposited FePt films on glass substrate increases with increasing Ts. Minor hysteresis loops reveal that domain-wall-pinning dominates the magnetic hardening of the FePt films. Post annealing at 400/spl deg/C substantially enhances coercivity and energy product for the Fe/sub 53/Pt/sub 47/ films on glass substrate. Ordering parameters were studied by XRD and quantitatively correlated to magnetic properties.
Electron-ion Equilibration in Nonradiative Shocks Associated With SN 1006

The ultraviolet spectrum of SN 1006 observed by the Hopkins Ultraviolet Telescope (HUT) is modeled to infer the degree of electron-ion equilibration at the nonradiative shocks in the remnant. Such an approach is possible since the spectrum has lines (He II λ1640) whose excitation is dominated by electrons, and others (C IV λ1550, N V λ1240, O VI λ1036) in which protons and other ions are more important, and the intensity ratio between these is sensitive to the electron-ion temperature ratio. We find substantially less than full equilibration, marginally consistent with existing plasma simulations but rather more suggestive of even lower equilibration than these studies would predict. The more stringent limits on the electron temperature resulting from this allow a more accurate determination of the distance to SN 1006. Our result is 1.8 ± 0.3 kpc.
Low-Level Thermodynamic, Kinematic, and Reflectivity Fields of Hurricane Guillermo (1997) during Rapid Intensification

Abstract From 0600 UTC 2 August to 1200 UTC 3 August Hurricane Guillermo (1997) deepened by 54 hPa over the eastern North Pacific Ocean, easily exceeding the thresholds that define rapid intensification (RI). The NOAA WP-3Ds observed a portion of this RI with similar two-aircraft missions on consecutive days. The aircraft jettisoned 70 successful global positioning system (GPS) dropwindsondes (or GPS sondes), which reveal how conditions in the lower troposphere on the octant to quadrant scale evolved within 250 km of the eye. Reflectivity fields demonstrate that the deepening is correlated with a spiraling in of the northern eyewall that reduces the eye diameter by 10 km. This behavior contrasts the more uniform contraction witnessed during eyewall replacement cycles. Mixing between the lower eye and eyewall, as detailed by other investigators, appears to have triggered the reduction in the eye diameter. After RI the eyewall remains asymmetrical with the tallest echo tops and heaviest rain rates located o.
Large‐bore copper‐vapor lasers: Kinetics and scaling issues

The scaling characteristics of large diameter (6≤d≤12 cm) high repetition‐rate copper‐vapor lasers are investigated using a radially dependent laser‐discharge model. Results of the model are verified with experimental data obtained on several devices including an 8‐cm‐diam 100‐W copper‐vapor laser. Two effects, penetration of the applied electric field into the plasma and gas heating, which we show are the primary considerations in volumetric scaling, are discussed in detail. Thermal constriction of the discharge resulting from gas heating is prevented by plasma skin effects that allow stable performance at large diameters. These same effects are shown to explain the sequential excitation of the laser levels, resulting in both temporally and spatially dependent behavior of the laser pulse. Projections of output power and light‐pulse characteristics are made for lasers up to 12 cm in diameter.
Wave Propagation in Piezoelectric Crystals

The propagation of plane waves in a piezoelectric medium has been studied. A simultaneous solution of Maxwell's field equations and Newton's law of force gives the necessary conditions for wave propagation in the infinite medium. By piezoelectric coupling, every electromagnetic wave has associated with it an elastic wave. Nonpiezoelectric crystals are, at best, birefringent electromagnetically and trirefringent acoustically. In piezoelectric media, the electromagnetic and elastic modes are coupled, thus giving five phase velocities for both the electromagnetic and acoustic waves. These media are therefore electromagnetically and acoustically pentrefringent. The slower electromagnetic waves are the field variations accompanying the elastic waves, while the fast elastic waves are the mechanical deformations accompanying the electromagnetic wave.The displacement in the elastic wave will differ in phase by ninety degrees from the electromagnetic wave, its amplitude being proportional to the electric field str.
Coulombic faulting from the grain scale to the geophysical scale: lessons from ice

Coulombic faulting, a concept formulated more than two centuries ago, still remains pertinent in describing the brittle compressive failure of various materials, including rocks and ice. Many questions remain, however, about the physical processes underlying this macroscopic phenomenology. This paper reviews the progress made in these directions during the past few years through the study of ice and its mechanical behaviour in both the laboratory and the field. Fault triggering is associated with the formation of specific features called comb-cracks and involves frictional sliding at the micro(grain)-scale. Similar mechanisms are observed at geophysical scales within the sea ice cover. This scale-independent physics is expressed by the same Coulombic phenomenology from laboratory to geophysical scales, with a very similar internal friction coefficient (μ ≈ 0.8). On the other hand, the cohesion strongly decreases with increasing spatial scale, reflecting the role of stress concentrators on fault initiation. Strong similarities also exist between ice and other brittle materials such as rocks and minerals and between faulting of the sea ice cover and Earth's crust, arguing for the ubiquitous nature of the underlying physics.
Optical properties and chemical bonding states with annealing conditions of ZnO nanofibers prepared by using the electrospinning method

We have prepared ZnO nanofibers by using the electrospinning method and have analyzed the variations in their structure, optical properties, and chemical bonding states with the annealing temperature and the annealing conditions. After annealing at 500 °C, the average diameter and the average grain size are determined to be approximately 170 nm and 50 nm, respectively. The ZnO nanofibers have a clearly visible dislocation-free crystal structure. The 2p level of Zn caused Zn-O bonds and the O 1s core level caused physisorbed O2. When the nanofibers are annealed at 700 °C, both ions exhibit shifts of the binding energies compared with those annealed at 500 °C. The observed band in the visible region shows a strong temperature dependence and a red-shift with the oxygen flow in annealing process, which is related to oxygen vacancies.
The Influence of Coastal Shape on Winter Mesoscale Air-Sea Interaction

Abstract In the case of cold air outbreaks, the combination of the coastal shape and the sea surface temperature (SST) pattern is shown to have a profound effect in establishing a low level mesoscale atmospheric circulation as a result of differential heating due to both variations in overwater path length and the SST. A convergence (or divergence) line then forms along a line exactly downwind of the major bend in the coastline. This is consistent with the structure of the cloud patterns seen in a high resolution Landsat picture of the cloud streets. The major features are also simulated well with a boundary layer model. The dominant convergence line is marked by notably larger clouds. To its cast the convective roll clouds grow downstream in accord with the deepening of the boundary layer. To its west (i.e., coastal side) near the convergence line where the induced pressure field forces a strong westerly component in the boundary layer, the wind shear across the inversion gives rise to Kelvin-Helmholtz w.
On the Bethe approximation

It is shown that in the limit of infinite impact energies the Coulomb-Bethe total collision cross section tends to twice the value given by the Born approximation. The discrepancy can be removed by introducing a lower cut-off in the partial-wave expansion in order to exclude close encounters for which the Coulomb-Bethe approximation is invalid. The approximation introduced by Bethe for electron impact excitation of a neutral target has been reformulated. The results generalised Bethe approximation is valid at all energies and involves a more precise definition of the cut-off than that suggested by Bethe. It also gives cross sections of correct form for transitions with vanishing oscillator strength.
Equipartition and Mass Segregation in a One-Dimensional Self-Gravitating System

The one-dimensional self-gravitating system (OGS) has been used as a simple model to study relaxation in N-body gravitational systems for several decades. In the OGS the gravitational field is uniform, and therefore simple algebraic equations which can be easily and rapidly solved on a computer govern the motion of the particles. Current computer technology allows for very long time dynamical simulations of reasonably large systems with little loss of numerical accuracy. Because the phase space of the OGS is compact, these systems do not suffer from some of the difficulties encountered in three dimensions (e.g., singularities, evaporation). However, a consequence of this is a somewhat tenuous connection with real galactic systems. Computer simulations of the OGS show that they tend to progress through various quasiequilibrium states as they evolve from arbitrary initial conditions. These quasiequilibrium states often last for very long times, and are approximately stationary. Fluctuations caused by changes in the mean field potential within the initial nonstationary distribution rapidly decay and the system reaches a state of microscopic relaxation, distinguished from the longer macroscopic time scale for relaxation to thermal equilibrium. Early predictions and dynamical simulations put thermal equilibrium on a time scale proportional to N 2 tc, where N is the number of particles and tc is the typical time for a particle to traverse the system [1,2]. Later work tended to refute these earlier claims by showing that the system was still far from equilibrium after 2N 2 tc [3,4].
New DOI Detector Using a Bottom and Side Readouts with a Cross-Arranged Scintillator Array for Positron Emission Tomography

We designed a depth-encoding positron emission tomography (PET) detector by using a bottom and side readout method with a cross-arranged scintillator array. To evaluate the characteristics of the novel detector module, we used the DETECT2000 simulation tool to perform the optical photon transport in the crystal array. The detector module consists of an M (column) × N (row) cross-arranged crystal array composed of M/3 sub-arrays consisting of N × 3 crystals. The second column of the sub-array is arranged perpendicular to the first and the third columns. The crystal is optically coupled to the crystals of the other columns; however, the surfaces between the crystals in the same column are treated as reflectors. A 6 × 5 crystal array consisting of two sub-arrays was considered for proof of concept. The two multi-pixel photon counter (MPPC) arrays are coupled to the bottom and one side of the crystal array, respectively. The x-y position is determined by the bottom MPPC array, and the side MPPC array gives depth information. All pixels in the x-y plane and the z direction were clearly distinguished.
Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses

Transparent solids may show strong absorption when irradiated by a high-intensity laser pulse. Such laser induced breakdown is due to the formation of a free-electron gas. We investigate theoretically the role of ionization processes in a defect-free crystal, including in our model two competing processes: strong-electricfield ionization and electron impact ionization. Free-electron heating is described in terms of electron-phononphoton collisions. Relaxation of the free electron gas occurs through electron-electron collisions and electronphonon collisions. The latter are also responsible for energy transfer from the free-electron gas to the phonon gas. We solve numerically a system of time dependent Boltzmann equations, where each considered process is included by its corresponding collision integral. Our results show formation, excitation, and relaxation of the electron gas in the conduction band. We find that strong-electric-field ionization is mainly responsible for free-electron generation. No avalanche occurs at femtosecond laser irradiation. The electron density and the internal energies of the subsystems are calculated. Critical fluences obtained using various criteria for damage threshold are in good agreement with recent experiments.
Axisymmetric two-sphere sedimentation in a shear thinning viscoelastic fluid : Particle interactions and induced fluid velocity fields

We investigate the link between particle interactions and induced flow patterns around two identical spheres sedimenting along their centerline in a polymeric fluid. The fluid is strongly shear thinning and, in agreement with previous results, the spheres are observed to chain even at large initial separation distances. The wake of a single particle displays an upward motion of fluid, i.e., a “negative wake” that is commonly observed in fluids with low extensional viscosities. We show that the features of this negative wake vary only weakly with the Deborah number. In the two-sphere case, the pattern of the induced flow depends on the sphere separation distance. The change in the flow pattern does not, however, induce any significant qualitative change in the sphere interactions. Upstream of the leading sphere and downstream of the trailing one along the sedimentation axis, the variations of the fluid velocity are well described by a single master curve for different values of the sphere separation distan.
Eleven New DA White Dwarf Variable Stars from the Sloan Digital Sky Survey

We report the discovery of 11 new variable DA white dwarf (ZZ Ceti) stars. Candidates were selected by deriving temperatures from model fits to spectra obtained from the Sloan Digital Sky Survey (SDSS). We also find objects whose temperatures and gravities indicate they lie within the instability strip for pulsation but were not observed to vary. Although the temperatures are based on relatively low signal-to-noise ratio spectra, an impure strip is unexpected, which if confirmed, has implications for DA asteroseismology. This work brings the total number of published variable DA white dwarf stars to 82.
Growth of BaTiO3-PVDF composite thick films by using aerosol deposition

Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 – 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ∼ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.
In-Situ hydrothermal synthesis of a MoS2 nanosheet electrode for electrochemical energy storage applications

A molybdenum disulfide (MoS2) nanosheet film was grown directly on a stainless-steel substrate by using an in-situ hydrothermal growth technique at 200 °C. The formation of an MoS2 hexagonal structure with a nanosheet-like morphology was confirmed by using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) while a layered MoS2 nanosheet structure was observed under an energy-filtering transmission electron microscope (EF-TEM). The electrochemical supercapacitor properties of the MoS2 nanosheet electrode were measured in 1-M aqueous Na2SO4 electrolyte by using cyclic voltammetry (CV) and charge/discharge technique, and the electrode’s specific capacitances were 91.29 F/g and 146.15 F/g, respectively. The concurrent double-layer capacitance and pseudo-capacitance behaviors of the electrode manifested themselves in the rectangular shape and redox peaks of the CV curve. The mesoporous MoS2 nanosheets were electrochemically stable for up to 1000 charge/discharge cycles.
Compact Double-fed Dual Annular Ring Printed Monopole Antenna for UWB Application

In this paper, we present a novel type of annular ring Printed Monopole Antenna (PMA) for ultra wideband (UWB) applications. The proposed antenna consists of a truncated ground plane and radiating patch with dual annular structure, which provides a wide usable bandwidth with high radiation pattern stability. Moreover, the effects of a double-fed structure inserted in the radiating patch, on the impedance matching and radiation behavior is investigated. Its impedance bandwidth, defined by measured voltage standing wave ratio (VSWR) less than 2, is from 3.1 to 16 GHz with a ratio of about 5.15 : 1. This novel monopole antenna has ultrawide impedance bandwidth, compact size (18 mm × 14 mm), low fabrication lost, and omni-directional H-plane radiation patterns, which are suitable for various broadband applications.
Analytical solutions for a double ring-shaped noncentral potential in D-dimensions

In the present study, a generalized double ring-shaped Coulomb noncentral potential is proposed, and the D-dimensional Schrödinger equation with this potential is examined in hyperspherical coordinates. The Nikiforov-Uvarov (N-U) method is applied to obtain the D-dimensional energy eigenvalues and the corresponding eigenfunctions. The angular/radial wavefunction is written in terms of Jacobi/Laguerre polynomials.
One-Dimensional model of hard rods with gravitational interactions

The study of one-dimensional hard rods with gravitational interactions was made by means of the isobaric and the canonical ensembles. The canonical partition function was obtained from the isobaric partition function by taking the inverse Laplace transform. The explicit closed forms for the canonical particle density and the higher-order molecular distribution functions were determined. The wall pressures, where the force exerted on the fluid by the walls, were obtained from both the partial derivative of the free energy with respect to the position of the walls and the contact value of the density determined from the one-particle density at the walls. The wall pressure implies that the hard rods with a gravitational interaction do not exhibit a phase transition. The partition function and the molecular distribution functions in the grand canonical ensemble are also reported.
Ferroelectric domain wall pinning at a bicrystal grain boundary in bismuth ferrite

The ferroelectric polarization switching behavior at the 24° (100) tilt grain boundary (GB) in an epitaxial multiferroic BiFeO3 bicrystal film is studied using piezoresponse force microscopy (PFM). The PFM amplitudes across positively and negatively poled GB regions suggest the presence of a frozen polarization component at the interface. The switching experiments demonstrate that the GB attracts the domain wall and acts as a pinning center. The PFM results are compared with conductive atomic force microscopy and spectroscopy, which suggest domain wall pinning at the GB can be partially attributed to increased conductance at the GB.