Miracle-dz/UniFAR-FTUs huggingface dataset:
Kelvin-Helmholtz instability at the magnetopause : theory and observations

Solar Wind (SW) and the Earth's magnetosphere interaction is mediated by the magnetopause. The SW carries with it the Interplanetary Magnetic Field (IMF) which interacts with northwards geomagnetic field lines causing magnetic reconnection (MR) events that make SW particles to be tranferred into the Earth's magnetosphere. If the IMF is directed northward, MR takes place at high latitude, but it is not efficient enough to justify the amount of SW plasma observed by satellites inside the magnetosphere. During northwards conditions one observe the formation of a wide boundary layer (BL) at the low latitude. This BL is thought to be driven by the the Kelvin-Helmholtz instability (KHI) , originating from the velocity shear between SW and the almost static near-Earth plasma. Numerical simulations (NS) have shown that the long time evolution of the KHI depends strongly on the initial large scale field profiles used as initial conditions. In order to make a further step towards the comprehension of this complex system, it is imperative to combine satellite data and NS. The idea here is to initialize NS by using in-situ observations of the main field profiles since only a correct initialization can reproduce the correct dynamics. The main results achieved in this work are: characterize the turbulence inside KH vortices and the small scale MR; select one event where there is a combination of a satellite measurements before and after KH develops, find that density and velocity profiles are shifted by a distance comparable to their shear lengths and that this initial shift cause a different evolution of the KHI leading to a final state in agreement with satellites observations.
Microstrip-fed slot antennas with suppressed harmonics

In this paper, microstrip-fed slot antennas with suppressed harmonics are proposed. To obtain this operation, conductor lines connected with ground plane are inserted in slot antennas. To verify the validation of the proposed antennas, the equivalent circuit analysis is presented. Also, the miniaturization and bandwidth enhancement of the antenna for various applications are achieved and analyzed through parameter study. From the measured return losses, input impedances, and radiation patterns, it is shown that the proposed antennas offer excellent harmonic suppression characteristic in harmonic bandwidth including the second and third harmonic frequencies.
Noncollisional excitation of low-lying states in gaseous nebulae

Consideration is given to the effects of processes other than electron collisional excitation on the energy level populations of species of C, N, and O. It is found that dielectronic as well as direct-radiative recombination may contribute significantly and in some cases be the major input to populating the low-lying metastable levels. It is concluded that the most pronounced changes occur when there is a large effective recombination coefficient to a level and when T(e) is low. The most dramatic change among the forbidden lines occurs for the O II forbidden lines. 31 references.
Saturation levels of neoclassical tearing modes in international thermonuclear experimental reactor plasmas

For the future ITER tokamak (International Thermonuclear Experimental Reactor) plasmas [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)] a simple and robust theoretical model for the prediction of the dynamics of neoclassical tearing modes (NTM) is a crucial topic. Presently, this theory is incomplete. Using full magnetohydrodynamic simulations, saturated NTM island widths significantly smaller than those predicted by any existing NTM theory are found. Nevertheless, these islands are sufficiently large to potentially alter the plasma confinement. Some reasons for the departure of the simulation results from the theoretical predictions are suggested and issues to be addressed to achieve a quantitative model are indicated.
Asymptotics for the SIMEX Estimator in Nonlinear Measurement Error Models

Abstract Cook and Stefanski have described a computer-intensive method, the SIMEX method, for approximately consistent estimation in regression problems with additive measurement error. In this article we derive the asymptotic distribution of their estimators and show how to compute estimated standard errors. These standard error estimators can either be used alone or as prepivoting devices in a bootstrap analysis. We also give theoretical justification to some of the phenomena observed by Cook and Stefanski in their simulations.
GA-based approaches for finding the minimum reference set for nearest neighbor classification

In this paper, we examine the ability of genetic algorithms to find a compact reference set for nearest neighbor classification. The task of genetic algorithms is to select a small number of reference patterns from a large number of given training patterns. Our pattern selection problem has two objectives: to maximize the classification performance of the reference set and to minimize the size of the reference set. In our genetic algorithm, they are combined into a single scalar fitness function using a constant weight for each objective. Thus our pattern selection problem is handled as a single-objective combinatorial optimization problem with 0-1 variables where "1" means the inclusion of the corresponding pattern in the reference set and "0" means the exclusion. In this paper, we first briefly explain our genetic algorithm for the pattern selection problem for nearest neighbor classification. Next we examine the ability of the genetic algorithm to find a compact reference set by computer simulations on commonly used real-world pattern classification problems. Finally, we suggest some extensions of our genetic algorithm.
Global rigidity for TNS Anosov Z^k actions

We consider a totally nonsymplectic Anosov action of Z^k which is either uniformly quasiconformal or pinched on each coarse Lyapunov distribution. We show that such an action on a torus is smoothly conjugate to an action by affine automorphisms. We also obtain similar global rigidity results for actions on an arbitrary compact manifold assuming that the coarse Lyapunov foliations are jointly integrable.
Interactive insight problem solving

Insight problem solving was investigated with the matchstick algebra problems developed by Knoblich, Ohlsson, Haider, and Rhenius (1999). These problems are false equations expressed with Roman numerals that can be made true bymoving one matchstick. In a first group participants examined a static two-dimensional representation of the false algebraic expression and told the experimenter which matchstick should be moved. In a second group, participants interacted with a three-dimensional representation of the false equation. Success rates in the static group for different problem types replicated the pattern of data reported in Knoblich et al. (1999). However, participants in the interactive group were significantly more likely to achieve insight. Problem-solving success in the static group was best predicted by performance on a test of numeracy, whereas in the interactive group it was best predicted by performance on a test of visuo-spatial reasoning. Implications for process models of problem solving are discussed.
Most probable ballistic waves in random media: a weak-fluctuation approximation and numerical results

Abstract A statistical approach to describe the time-space pulse evolution in single realizations of two- and three-dimensional random media is presented. For this purpose, we construct the ensemble-averaged wavenumber of a plane wave. The wavenumber is obtained by a combination of the Rytov and Bourret approximations for the log-amplitude and phase increment, both related by the Kramers-Kronig relations. The real part of the wavenumber is related to the phase velocity, whereas its imaginary part denotes the attenuation coefficient of the ballistic wavefield. The validity range is limited by the weak-fluctuation regime, but has practically no restrictions in the frequency domain. We show that this wavenumber is a partially self-averaged quantity. This means that the wavenumber is a Gaussian-distributed quantity exhibiting decreasing relative fluctuations while the wave travels a finite distance such that it is still in a weak-fluctuation regime. Then, the ensemble-averaged wavenumber carries the information of maximum probability realizations. The Green's function constructed with this wavenumber corresponds to the most probable ballistic wave. Using this Green's function, it is possible to characterize single-wavefield realizations in single realizations of random media. We verify the concept and analytic results with the help of finite-difference simulations of waves propagating in two-dimensional random media. We demonstrate the partial self-averaging property of the wavefield attributes by computing their relative standard deviations as a function of propagation distance L. Within the weak-fluctuation regime, these relative standard deviations decrease as 1/√L, indicating that the process of self-averaging takes place. Reconstructing the joint probability density of amplitudes and phases of ballistic waves allows us to identify most probable ballistic waves. They show a good agreement with the analytic results.
Are flows electromagnetically forced in thin stratified layers two dimensional

The relaxation of three-dimensional perturbations in flows generated in thin density stratified layers is discussed. It is found that the relaxation time for such perturbations is small compared to the other characteristic times of the system. These results offer a basis to assess the two dimensionality of freely decaying turbulence prepared in such configurations.
Sign inversion of the optical torque on the nematic director enhanced by anthraquinone dye dopants stable to the light action

By analyzing the total and on-axis transmittance of the laser beam we studied the enhanced light-induced director reorientation (Jánossy effect) in a nematic liquid crystal doped with anthraquinone dye molecules that do not have photoinduced conformational transformations. The obtained dependence on the angle between the light polarization E and the initial director n0 shows: first order director reorientation (DR) transition with hysteresis for E ⊥ n0; second order reversible DR transition with the extremely low threshold intensity for E || n0; sign inversion of the nonlinear refractive index and DR in the intermediate geometry. The data suggest a presence of two different kinds of dipoles in the system: those absorbing light and those giving rise to the nonlinear refractive index.
Recursive M-estimators of location and Scale for Dependent Sequences

Abstract : Recursive M-estimators of location and scale may be obtained via stochastic approximation algorithms. We consider the case when the observations can be described by a strictly stationary process satisfying certain strong mixing conditions and results on strong convergence are given. The asymptotic distributions of the estimators for sequences of independent observations are also discussed.
Spatial and Temporal Epidemic Prediction by Neural Networks

In Section 1, we will begin with a brief treatment of the SEIR model, a common tool for describing the spread of a disease over time. We first give an overview of the traditional, deterministic model, and then explain how we have incorporated stochastic processes into the model to increase the realism. Finally, we show how the revised stochastic model can be altered to model an epidemic on a graph.
From biased robots to race as technology

Ranking search results, filtering spam e-mails, recommending movies and books, evaluating credit card fraud, diagnosing malignant cells in cancer research, selecting job applicants – more and more tasks are being carried out by new media technologies such as machine learning algorithms. Their logic does not only simplify our daily approach to large masses of information but also applies at a higher level in the observation and regulation of population flows. They are for instance employed for policing purposes (e
High Resolution Schemes for Conservation Laws With Source Terms.

This memoir is devoted to the study of the numerical treatment of source terms in hyperbolic conservation laws and systems. In particular, we study two types of situations that are particularly delicate from the point of view of their numerical approximation: The case of balance laws, with the shallow water system as the main example, and the case of hyperbolic equations with stiff source terms. In this work, we concentrate on the theoretical foundations of highresolution total variation diminishing (TVD) schemes for homogeneous scalar conservation laws, firmly established. We analyze the properties of a second order, flux-limited version of the Lax-Wendroff scheme which avoids oscillations around discontinuities, while preserving steady states. When applied to homogeneous conservation laws, TVD schemes prevent an increase in the total variation of the numerical solution, hence guaranteeing the absence of numerically generated oscillations. They are successfully implemented in the form of flux-limiters or slope limiters for scalar conservation laws and systems. Our technique is based on a flux limiting procedure applied only to those terms related to the physical flow derivative/Jacobian. We also extend the technique developed by Chiavassa and Donat to hyperbolic conservation laws with source terms and apply the multilevel technique to the shallow water system. With respect to the numerical treatment of stiff source terms, we take the simple model problem considered by LeVeque and Yee. We study the properties of the numerical solution obtained with different numerical techniques. We are able to identify the delay factor, which is responsible for the anomalous speed of propagation of the numerical solution on coarse grids. The delay is due to the introduction of non equilibrium values through numerical dissipation, and can only be controlled by adequately reducing the spatial resolution of the simulation. Explicit schemes suffer from the same numerical pathology, even after reducing the time step so that the stability requirements imposed by the fastest scales are satisfied. We study the behavior of Implicit-Explicit (IMEX) numerical techniques, as a tool to obtain high resolution simulations that incorporate the stiff source term in an implicit, systematic, manner.
Recent advancements in transparent ceramics and crystal fibers for high power lasers

In this paper, we present our recent progress in the development of rare-earth (Yb3+ or Ho3+) doped Lu2O3 and Y2O3 sesquioxides for high power solid state lasers. We have fabricated high quality transparent ceramics using nano-powders synthesized by a co-precipitation method. This was accomplished by developments in high purity powder synthesis and low temperature scalable sintering technology developed at NRL. The optical, spectral and morphological properties as well as the lasing performance from our highly transparent ceramics are presented. In the second part of the paper, we discuss our recent research effort in developing cladded-single crystal fibers for high power single frequency fiber lasers has the potential to significantly exceed the capabilities of existing silica fiber based lasers. Single crystal fiber cores with diameters as small as 35μm have been drawn using high purity rare earth doped ceramic or single crystal feed rods by the Laser Heated Pedestal Growth (LHPG) process. Our recent results on the development of suitable claddings on the crystal fiber core are discussed.
Neutrino Induced Coherent Pion Production

Neutrino-induced coherent pion production is an important channel for the study of neutrino-nucleus interactions. It is both a dangerous background for νe oscillation experiments, and a critical component required for precise understanding of neutrino-nucleus pion production in general. The body of experimental evidence for coherent pion production at high neutrino energies is reviewed. This data is described well by the Rein-Sehgal model, which is described and studied. In light of recent low energy limits set below the Rein-Sehgal model cross-section an alternative low energy model, the Alvarez-Ruso model, was implemented in the neutrino interaction simulation GENIE. The results of this simulation are compared with those from the Rein-Sehgal model, and briefly with those from other models. Finally, a search for νμ-induced charged-current (CC) coherent pion production on 12C was conducted at a mean neutrino energy of 0.86 GeV, using data from the T2K experiment's off-axis near detector. A 3.0 σ excess of events was found above the background prediction, constituting the first experimental evidence of CC coherent pion production below 7 GeV. Preliminary attempts to interpret this excess in the context of the Rein-Sehgal and Alvarez-Ruso models found cross-sections consistent with the limits set by SciBooNE.
The generalized Boltzmann equation, generalized hydrodynamic equations and their applications

The generalization of the Boltzmann equation is realized by taking into account the alteration of the distribution function on scales of the collision time order. The generalized hydrodynamic equations are derived on the basis of the generalized Boltzmann equation. The strict theory of turbulence on the Kolmogorov scale is developed. Examples and issues are given for the shock wave structure and sound wave propagation calculations.
On the Struve transformation

The Struve or $\mathcal{H}_\nu $ transformation is defined for suitable functions f by \[ \left( {\mathcal{H}_\nu f} \right)(x) = \int_0^\infty {(xt)^{{1 / 2}} } \mathbb{H}_\nu (xt)f(t)dt,\] where $\mathbb{H}_\nu $ is the Struve function. It is known to be bounded on weighted $L_p $ spaces with weights $t^{p\mu - 1} $ if $1 \leq p - (\nu + \frac{1}{2})$. Here inversion formulas are given for $\mu \leq - (\nu + \frac{1}{2})$.
Classifying Active Galactic Nuclei from the zCOSMOS 20k spectroscopic survey. Looking for a mass trend

We analyze the evolution of galaxy spectral properties up to z = 1 by using galaxies from the zCOSMOS-Bright 20k spectroscopic survey. We divide the sample in several mass-redshift bins to obtain stacked galaxy spectra and measure emission lines with a higher S/N. The aim of this work is to investigate whether it is possible to highlight some evidence of AGN activity in suppressing star formation during the transitional phase of galaxies from late to early type, with a particular look on a possible trend of the galaxy total stellar mass. Our main finding is a clear role of the total stellar mass in leading galaxy evolution. As the diagnostic diagrams indicate, the objects show a progressive shift towards the AGNs region with increasing total stellar mass. Additionally, the composites follow, for a fixed redshift bin, evolutionary tracks that move from the upper part of the SF galaxies sequence down to the same metallicity sequence. For stellar masses greater than 1.6 × 1010 solar masses, the objects start being classified as composites or AGNs. This indicates that AGNs mostly act at the highest mass bins, where our sample is firstly populated by passive galaxies that have experienced the quenching. The evidence that older stellar populations inhabit more massive galaxies, together with the increasing AGN detection rate with increasing masss, suggest a scenario in which AGNs might act to quench the star formation and, then, contribute to the transformation from young blue late-type galaxies to old red early-type galaxies.
A modified PSO based particle filter algorithm for object tracking

In this paper, a modified particle swarm optimization (PSO) approach, particle swarm optimization with ε- greedy exploration εPSO), is used to tackle the object tracking. In the modified εPSO algorithm, the cooperative learning mechanism among individuals has been introduced, namely, particles not only adjust its own flying speed according to itself and the best individual of the swarm but also learn from other best individuals according to certain probability. This kind of biologically-inspired mutual-learning behavior can help to find the global optimum solution with better convergence speed and accuracy. The εPSO algorithm has been tested on benchmark function and demonstrated its effectiveness in high-dimension multi-modal optimization. In addition to the standard benchmark study, we also combined our new εPSO approach with the traditional particle filter (PF) algorithm on the object tracking task, such as car tracking in complex environment. Comparative studies between our εPSO combined PF algorithm with those of existing techniques, such as the particle filter (PF) and classic PSO combined PF will be used to verify and validate the performance of our approach.
Finite Element Large Deflection Random Response Of Thermally Buckled Plates

Abstract The governing non-linear equations of motion are derived for a rectangular isotropic plate subjected to a combined thermal-acoustic loading. The thermal loading is taken to be a steady state temperature distribution, and the acoustic loading is considered to be a stationary Gaussian pressure with zero mean and uniform magnitude and phase over the plate surface. With these types of loads, the thermal-acoustic analysis can be separated into two problems: (1) thermal post-buckling; and (2) random vibration of the thermally buckled plate. Since both analyses are non-linear, iterative techniques are used to solve each. For the random vibration analysis, the method of equivalent linearization is used; both auto- and cross-correlation terms are included. Results obtained using the present formulation are compared with previous classical equivalent linearization results.
High energy proton acceleration in interaction of short laser pulse with dense plasma target

The generation of high energy protons from the interaction of a short laser pulse with a dense plasma, accompanied by a preformed low density plasma, has been studied by particle-in-cell simulations. The proton acceleration toward the laser direction in the preformed plasma is characterized by a time-dependent model and the peak proton energy is given. The effect of electron recirculation on the rear side sheath acceleration is discussed and it is found that the peak proton energy increases in inverse proportion to the target thickness. These results shed light on the peak proton energy dependence on laser intensity, laser pulse length, and target thickness. Finally the optimal parameters of the laser pulse for large ion peak energy and conversion efficiency are discussed.