Miracle-dz/UniFAR-FTUs huggingface dataset:
The effect of a guide field on the structures of magnetic islands formed during multiple X line reconnections: Two‐dimensional particle‐in‐cell simulations

A magnetic island plays an important role in magnetic reconnection. In this paper, using a series of two‐dimensional particle‐in‐cell simulations, we investigate the magnetic structures of a magnetic island formed during multiple X line magnetic reconnections, considering the effects of the guide field in symmetric and asymmetric current sheets. In a symmetric current sheet, the current in the x direction forms a tripolar structure inside a magnetic island during antiparallel reconnection, which results in a quadrupole structure of the out‐of‐plane magnetic field. With the increase of the guide field, the symmetry of both the current system and out‐of‐plane magnetic field inside the magnetic island is distorted. When the guide field is sufficiently strong, the current forms a ring along the magnetic field lines inside a magnetic island. At the same time, the current carried by the energetic electrons accelerated in the vicinity of the X lines forms another ring at the edge of the magnetic island. Such a dual‐ring current system enhances the out‐of‐plane magnetic field inside the magnetic island with a dip in the center of the magnetic island. In an asymmetric current sheet, when there is no guide field, electrons flow toward the X lines along the separatrices from the side with a higher density and are then directed away from the X lines along the separatrices to the side with a lower density. The formed current results in the enhancement of the out‐of‐plane magnetic field at one end of the magnetic island and the attenuation at the other end. With the increase of the guide field, the structures of both the current system and the out‐of‐plane magnetic field are distorted.
Luminescence enhancement and emission color adjustment of white organic light-emitting diodes with quantum-well-like structures

In recent years, white-light organic light-emitting diodes (OLEDs) have attracted considerable attention because of their potential applications in displays, backlight units, and general lighting. In this paper, we describe the fabrication of a high-luminance white-light OLED with dual-emission layers (EMLs). The 2,9-dimethyl-4,7-diphenyl-1,10-phenanhroline hole blocking layers (HBLs) were prepared to enhance the luminance and adjust the emission color of the device. For the device with a single-HBL structure, the excess holes were accumulated at the red EML (REML)/HBL1 interface. Consequently, most of the carriers were recombined in the REML, which led to a redshifted light emission. On the contrary, the device with a dual-HBL structure showed a blueshifted light emission. The device with a quantum-well-like structure increased the carrier trapping and recombination probabilities; as a result, a lower current density and a higher luminance intensity of the device were achieved. The maximum luminance inte.
A Simple Empirical Model for Predicting the Decay of Tropical Cyclone Winds after Landfall

Abstract An empirical model for predicting the maximum wind of landfalling tropical cyclones is developed. The model is based upon the observation that the wind speed decay rate after landfall is proportional to the wind speed. Observations also indicate that the wind speed decays to a small, but nonzero, background wind speed. With these assumptions, the wind speed is determined from a simple two-parameter exponential decay model, which is a function of the wind speed at landfall and the time since landfall. A correction can also be added that accounts for differences between storms that move inland slowly and storms that move inland rapidly. The model parameters are determined from the National Hurricane Center best track intensities of all U.S. landfalling tropical cyclones south of 37°N for the period 196793. Three storms that made landfall in Florida prior to 1967 were also included in the sample. Results show that the two-parameter model explains 91% of the variance of the best track intensity chan.
Error Characteristics of Two Grid Refinement Approaches in Aquaplanet Simulations: MPAS-A and WRF

AbstractThis study compares the error characteristics associated with two grid refinement approaches including global variable resolution and nesting for high-resolution regional climate modeling. The global variable-resolution model, Model for Prediction Across Scales-Atmosphere (MPAS-A), and the limited-area model, Weather Research and Forecasting Model (WRF), are compared in an idealized aquaplanet context. For MPAS-A, simulations have been performed with a quasi-uniform-resolution global domain at coarse (1°) and high (0.25°) resolution, and a variable-resolution domain with a high-resolution region at 0.25° configured inside a coarse-resolution global domain at 1° resolution. Similarly, WRF has been configured to run on a coarse (1°) and high (0.25°) tropical channel domain as well as a nested domain with a high-resolution region at 0.25° nested two-way inside the coarse-resolution (1°) tropical channel. The variable-resolution or nested simulations are compared against the high-resolution simulation.
Lithium depletion and rotation in main-sequence stars

Lithium abundances were measured in nearly 200 old disk-population F stars to examine the effects of rotational braking on the depletion of Li. The sample was selected to be slightly evolved off the main sequence so that the stars have completed all the Li depletion they will undergo on the main sequence. A large scatter in Li abundances in the late F stars is found, indicating that the Li depletion is not related to age and spectral type alone. Conventional depletion mechanisms like convective overshoot and microscopic diffusion are unable to explain Li depletion in F stars with thin convective envelopes and are doubly taxed to explain such a scatter. No correlation is found between Li abundance and the present projected rotational velocity and some of the most rapid rotators are undepleted, ruling out meridional circulation as the cause of Li depletion. There is a somewhat larger spread in Li abundances in the spun-down late F stars compared to the early F stars which should remain rotationally unaltered on the main sequence. 85 refs.
On the differences between plage and quiet sun in the solar photosphere

Time sequences of interleaved observations of the continuum intensity, longitudinal magnetic field, vertical velocity in the midphotosphere, and the line-center intensity in Ni I 6768 A were obtained in an active-region plage and the surrounding relatively field-free area near disk center. Spacetime Fourier filtering techniques are used to separate the convective and oscillatory components of the solar atmosphere. The properties of the photosphere are found to differ qualitatively and quantitatively between the plage, where the field is 150 G or more, and its quiet surroundings. The scale of granulation is smaller, the contrast lower, and the temporal evolution slower in the plage than the quiet sun. In the plage, the vertical velocity is reduced in amplitude compared to the quiet sun, and there is little evidence of a granulation pattern, while in the quiet sun the vertical flow pattern is similar in size and shape to the underlying granulation pattern in the continuum.
A score test for extra zeros in negative binomial mixed models

The negative binomial (NB)-mixed regression in many situations is more appropriate for analysing the correlated and over-dispersed count data. In this paper, a score test for assessing extra zeros against the NB-mixed regression in the correlated count data with excess zeros is developed. The sampling distribution and power of the score test statistic is evaluated using a simulation study. The results show that under a wide range of conditions, the score statistic performs satisfactorily. Finally, the use of the score test is illustrated on DMFT index data of children aged 12 years old.
Nonlinear evolution of Buneman instability and its implication for electron acceleration in high Mach number collisionless perpendicular shocks

Nonlinear evolution of the Buneman instability and its application to electron acceleration in collisionless shocks are discussed. Two-dimensional particle-in-cell simulations show that the saturation level of the instability is reduced from one-dimensional simulation results. It is demonstrated that the reduced saturation level is due to the resonant wave-particle interactions with large amplitude obliquely propagating waves. A new estimate for the saturation level is given by considering the interactions with oblique modes. The effects of the large amplitude oblique modes on electron shock surfing acceleration that is mainly controlled by the Buneman instability are also investigated. Two-dimensional particle-in-cell simulations of the shock transition region are performed by adopting a local model with the periodic boundary condition. The results indicate that the presence of oblique modes introduces a stochastic behavior to the trajectories of energetic electrons. The maximum energy is limited by the .
Multifrequency observations of the wide-angle tail radio source 1313+073

Les observations presentees apportent une information detaillee quant aux distributions de l'indice spectral, a la mesure de rotation et a la depolarisation dans la source. On presente egalement des donnees spectroscopiques qui suggerent que 1313+073 appartient a un amas de galaxies dont le deplacement vers le rouge est z=0,057
Introduction to Spectral Theory: With Applications to Schrödinger Operators

1 The Spectrum of Linear Operators and Hilbert Spaces. - 2 The Geometry of a Hilbert Space and Its Subspaces. - 3 Exponential Decay of Eigenfunctions. - 4 Operators on Hilbert Spaces. - 5 Self-Adjoint Operators. - 6 Riesz Projections and Isolated Points of the Spectrum. - 7 The Essential Spectrum: Weyl's Criterion. - 8 Self-Adjointness: Part 1. The Kato Inequality. - 9 Compact Operators. - 10 Locally Compact Operators and Their Application to Schrodinger Operators. - 11 Semiclassical Analysis of Schrodinger Operators I: The Harmonic Approximation. - 12 Semiclassical Analysis of Schrodinger Operators II: The Splitting of Eigenvalues. - 13 Self-Adjointness: Part 2. The Kato-Rellich Theorem 131. - 14 Relatively Compact Operators and the Weyl Theorem. - 15 Perturbation Theory: Relatively Bounded Perturbations. - 16 Theory of Quantum Resonances I: The Aguilar-Balslev-Combes-Simon Theorem. - 17 Spectral Deformation Theory. - 18 Spectral Deformation of Schrodinger Operators. - 19 The General Theory of Spectral Stability. - 20 Theory of Quantum Resonances II: The Shape Resonance Model. - 21 Quantum Nontrapping Estimates. - 22 Theory of Quantum Resonances III: Resonance Width. - 23 Other Topics in the Theory of Quantum Resonances. - Appendix 1. Introduction to Banach Spaces. - A1.1 Linear Vector Spaces and Norms. - A1.2 Elementary Topology in Normed Vector Spaces. - A1.3 Banach Spaces. - A1.4 Compactness. - 1. Density results. - 2. The Holder Inequality. - 3. The Minkowski Inequality. - 4. Lebesgue Dominated Convergence. - Appendix 3. Linear Operators on Banach Spaces. - A3.1 Linear Operators. - A3.2 Continuity and Boundedness of Linear Operators. - A3.3 The Graph of an Operator and Closure. - A3.4 Inverses of Linear Operators. - A3.5 Different Topologies on L(X). - Appendix 4. The Fourier Transform, Sobolev Spaces, and Convolutions. - A4.1 Fourier Transform. - A4.2 Sobolev Spaces. - A4.3 Convolutions. - References.
The moments of the time to ruin in dependent Sparre Andersen models with Coxian claim sizes

A very general class of dependent Sparre Andersen models with Coxian claim sizes (e.g. Landriault et al. 2014) is considered in this paper. The moments of the time to ruin are studied under this class. An analytical form is provided for the moments, which involves solving linear systems of equations. Numerical examples are then considered to further study the properties of the mean and variance of the time to ruin.
Mechanically robust nanoparticle stabilized transparent liquid marbles

Optically transparent liquid marbles were made from water and glycerol drops embedded in surface-treated fumed silica nanoparticles. The mechanical robustness of such liquid marbles is shown to be greater than similar marbles made from microparticulate poly(tetrafluoroethylene), both under compressive and tensile loading conditions. Using liquid evaporation data and environmental scanning electron microscope images, we demonstrate that their robustness may be attributed to a nanoparticulate elastic thin film that self-assembles on the liquid-vapor interface.
An edge‐based smoothed finite element method for 3D analysis of solid mechanics problems

The edge‐based smoothed finite element method (ES‐FEM) was proposed recently in Liu, Nguyen‐Thoi, and Lam to improve the accuracy of the FEM for 2D problems. This method belongs to the wider family of the smoothed FEM for which smoothing cells are defined to perform the numerical integration over the domain. Later, the face‐based smoothed FEM (FS‐FEM) was proposed to generalize the ES‐FEM to 3D problems. According to this method, the smoothing cells are centered along the faces of the tetrahedrons of the mesh. In the present paper, an alternative method for the extension of the ES‐FEM to 3D is investigated. This method is based on an underlying mesh composed of tetrahedrons, and the approximation of the field variables is associated with the tetrahedral elements; however, in contrast to the FS‐FEM, the smoothing cells of the proposed ES‐FEM are centered along the edges of the tetrahedrons of the mesh. From selected numerical benchmark problems, it is observed that the ES‐FEM is characterized by a higher accuracy and improved computational efficiency as compared with linear tetrahedral elements and to the FS‐FEM for a given number of degrees of freedom. Copyright © 2013 John Wiley & Sons, Ltd.
Isolated Singularities for Fully Nonlinear Elliptic Equations

Abstract We obtain Serrin type characterization of isolated singularities for solutions of fully nonlinear uniformly elliptic equations F ( D 2 u )=0. The main result states that any solution to the equation in the punctured ball bounded from one side is either extendable to the solution in the entire ball or can be controlled near the centre of the ball by means of special fundamental solutions. In comparison with semi- and quasilinear results the proofs use the viscosity notion of generalised solution rather than distributional or Sobolev weak solutions. We also discuss one way of defining the expression − P + λ , Λ ( D 2 u ), ( P − λ , Λ ( D 2 u )) as a measure for viscosity supersolutions (subsolutions) of the corresponding equation. Here P ± λ , Λ are the Pucci extremal operators.
The plasma wave signature of a ``magnetic hole'' in the vicinity of the magnetopause

Magnetic holes are occasionally observed in the vicinity of the magnetopause. These holes are similar to crater flux transfer events in size and magnetic signature, but have a lower magnetic field and different wave spectra. An exemplary magnetic hole has been observed by the AMPTE IRMspacecraft on September 4, 1984, in the early evening sector of the magnetosphere. The authors here investigate the plasma wave spectra inside and in the immediate vicinity of the hole and their relation to the plasma properties of the hole. In side the hole where magnetic field levels are lowest, wave emissions between a few times the ion cyclotron frequency and the plasma frequency drop to levels close to the instrumental noise level. This behavior is similar to that observed in the artificial comet and plasma cloud releases in the solar wind, magnetosheath, and magnetospheric tail produced by the same satellite. Electromagnetic waves with frequency up to several times the ion cyclotron frequency are found inside the hole with relatively strong amplitudes ({delta}B/B {approx} 1). These could represent either whistler waves or ion cyclotron waves. Estimations of the local electron plasma frequency suggest that this hole has a plasma density as high as 200 cm{supmore » {minus}3}, whereas the ambient plasma maintains a density of 10-30 cm{sup {minus}3}. In contrast to the low activity in the parts of the hole where the magnetic field is lowest, the boundaries contain very intense broadband noise from less than 1 Hz to several kHz. These could be generated by the lower hybrid drift instability. The energy density of the boundary waves, assuming they are lower hybrid waves, is far greater than the energy density of the low-frequency waves inside the hole; hence, it is plausible that the interior waves represent the leakage of waves from the boundary region into the hole. Some ideas about the origin of the magnetic holes are discussed. « less
Theoretical study of the collisional depolarization and of the Hanle effect in the Na I D$\mathsf{_{2}}$ line observed on the solar limb

In recent years, Landi Degl' Innocenti (1998, 1999) has proposed a model of the polarization spectrum of the Nai D lines observed near the solar limb, based on lower level polarization effects. By so doing, he obtains a remarkable agreement between his model and the observations, so that he comes to a conclusion about a paradox, because the existence of lower level polarization is incompatible with a magnetic field strength higher than 10 mGauss (except vertical), and with possible depolarizing collision effects. In the present paper, we investigate the depolarizing collision effects (collisions with neutral hydrogen) by using the collisional rates computed with ab-initio and quantum chemistry methods by Kerkeni (2001; see also Kerkeni et al. 2000, and Kerkeni 2002). We solve the statistical equilibrium equations for the atomic density matrix, taking into account these depolarizing collisions. We investigate the effect of a weak magnetic field (Hanle effect). Our results indicate that the lower levels should be completely depolarized by the collisions at the depth where the NaI D lines are formed. Furthermore, large values of the lower level alignment such as those introduced by Landi Degl'Innocenti in his model to get a good theoretical fit of the observations, seem to us unlikely, as our computations confirm. Thus, as the agreement between the model by Landi Degl'Innocenti and the observations is however very convincing, the paradox is confirmed, reinforced and increased by our results.
Tracer particle trapping times in pressure-gradient-driven turbulence in toroidal geometry and their connection to the dynamics of large-scale cycles

The continuous time random walk (CTRW) approach allows us to construct transport models based on waiting times and particle flight distributions. The connection between the distribution of particle flights and the distribution of radial extents of the connected components of the flow has already been shown by Garcia et al (2009 Phys. Rev. E 80 046410). Here, the connection between the large-scale cycles of the flow structure and the trapping times is explored. It is shown that the distribution of trapping times of the tracers is given by the distribution of lifetimes of the large-scale cycles in the flow structure. This distribution has a power tail, which is the result of the dynamics of avalanche transport.
Cochlear nonlinearity and second filter; psychophysical estimation of model parameters

Recently we proposed a theoretical model for cochlear nonlinearity and second filter [J. Acoust. Soc. Am. 59, 408–423 (1971)]. From psychophysical two‐tone suppression data we attempted to estimate characteristics of the two filters and of the compressive nonlinearity y = xν. In our first experiments probe frequency (suppressee as well as test probe) was 1 kHz. Masker (suppressor) frequency was a parameter. We used the pulsation‐threshold method, where masker plus suppressee and test probe alternated. The pulsation threshold of the test probe was measured as a function of masker level, suppressee level being a fixed parameter. Data curves typically are characterized by a horizontal part, a descending part, and an ascending part. The descending part, reflecting suppression contains the wanted information. Insofar as our interpretation of the data is valid, we estimate for ν a value from 0.25 to 0.8, depending on musket frequency. The low‐frequency part of the second‐filter characteristic levels off at appr.
How to construct a triangular matrix of a given order

In this article we consider the elements in upper triangular finite and infinite dimensional matrix groups over fields, whose order is equal to (). For the case when the characteristic of does not divide, we give a description of such elements. Next using this criterion, we show how to find the number of these elements in finite dimensional groups when is a finite field.
Size effects on static and dynamic properties of ferroelectric nanoparticles

Ferroelectric nanoparticles are described by a microscopic model which enables one to find the macroscopic polarization as well as the excitation energy of the soft mode and its damping with dependence on the temperature and the size of the particles. The constituents of the material are arranged in shells, and their interaction depends on both the coupling at the surface and within the bulk. A Green's function technique in real space is applied to analyze the Ising model in a transverse field, which is modified in such a manner as to be able to study also spherical nanoparticles. Furthermore, we investigate the influence of size effects on the critical temperature. Whereas the excitation energy is lowered significantly with decreasing particle size, the damping is enhanced. Additionally, we consider the influence of defects on the excitation spectrum. The theoretical results are compared with experimental data.
Topological Effects on the Performance of Transportation Networks

We investigate the influence of the network topology on the performance (characterized by the total system cost and maximal traffic volume) of transportation networks, where the weights are not static (constant), but dynamic (a function of the flow on the link). Four classes of networks are used in the simulation, including regular networks, random networks, small-world networks and scale-free networks. The initial simulation results show that topologies play important roles on the performance of transportation networks, and random networks have better performance than other networks. Also, we find that there are distinct difference of the link flow distribution for various networks in both the distribution function form and the span between the minimum and the maximum of the link flow, explaining the difference of the performance among distinct networks. These findings will be useful in network design problems of transportation systems.
Short-Run and Long-Rub Causality in Time Series: Theory.

Causality in Granger's sense is defined in terms of predictibility one period ahead. The notion of causality is generalized by considering causality at any given horizon 1 (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.) (This abstract was borrowed from another version of this item.)