Miracle-dz/UniFAR-FTUs huggingface dataset:
Modelling of Density Limit Phenomena in Toroidal Helical Plasmas

The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the Wendelstein 7-AS (W7-AS) stellarator.
A Proposed Tropical Rainfall Measuring Mission (TRMM) Satellite

Abstract The Tropical Rainfall Measuring Mission (TRMM) satellite is planned for an operational duration of at least three years, beginning in the mid-1990's. The main scientific goals for it are to determine the distribution and variability of precipitation and latent-heat release on a monthly average over areas of about 105 km2, for use in improving short-term climate models, global circulation models and in understanding the hydrological cycle, particularly as it is affected by tropical oceanic rainfall and its variability. The TRMM satellite's instrumentation will consist of the first quantitative spaceborne weather radar, a multichannel passive microwave radiometer and an AVHRR (Advanced Very High Resolution Radiometer). The satellite's orbit will be low altitude (about 320 km) for high resolution and low inclination (30° to 35°) in order to visit each sampling area in the tropics about twice daily at a different hour of the day. A strong validation effort is planned with several key ground sites to .
Analysis and modelling of turbulent flow in an axially rotating pipe

The analysis and modelling of the structure of turbulent flow in a circular pipe subjected to an axial rotation is presented. Particular attention is paid to determining the terms in various turbulence closures that generate the two main physical features that characterize this flow: a rotationally dependent axial mean velocity and a rotationally dependent mean azimuthal or swirl velocity relative to the rotating pipe. It is shown that the first feature is well represented by two-dimensional explicit algebraic stress models but is irreproducible by traditional two-equation models. On the other hand, three-dimensional frame-dependent models are needed to predict the presence of a mean swirl velocity. The latter is argued to be a secondary effect which arises from a cubic nonlinearity in standard algebraic models with conventional near-wall treatments. Second-order closures are shown to give a more complete description of this flow and can describe both of these features fairly well. In this regard, quadratic pressure–strain models perform the best overall when extensive comparisons are made with the results of physical and numerical experiments. The physical significance of this problem and the implications for future research in turbulence are discussed in detail.
Magnetic Properties of ZnFe2O4 as a 3-D Geometrical Spin Frustration System

Magnetic properties of ZnFe 2 O 4 were studied for various specimens prepared by different thermal and artificial treatments using neutron scattering, Mossbauer spectroscopy and DC and AC susceptibilities. We found a strong correlation between the magnetic Bragg peak intensity and the Mossbauer absorption line-width. Comparing with the susceptibility data, it is discussed what are the intrinsic magnetic properties of ZnFe 2 O 4 as a typical 3-D geometrical spin frustration system.
Investigating the effect of Casimir and van der Waals attractions on the electrostatic pull-in instability of nano-actuators

This paper investigates the effect of dispersion (van der Waals and Casimir) forces on the pull-in instability of cantilever nano-actuators by considering their range of application. Adomian decomposition is introduced to obtain an analytical solution of the distributed parameter model. Dispersion forces decrease the pull-in deflection and voltage of a nano-actuator. However, the fringing field increases the pull-in deflection while decreasing the pull-in voltage of the actuator. The minimum initial gap and the detachment length of the actuator that does not stick to the substrate due to van der Waals and Casimir attractions were determined. Furthermore, the proposed approach is capable of determining the stress distribution of the actuator at the onset of instability. It is seen that Casimir and van der Waals attractions effectively reduce the maximum value of stress resultants at the onset of instability. The results indicate that Adomian decomposition is a reliable method for simulating nano-structures at submicrometer ranges.
A note on the least quadratic non-residue of the integer-sequences

Throughout the text p denotes a prime number. We also use the following notations: A <C B means that |yl| < cB for some positive number c which may depend only on a,. ,b a,. , 6, (a/p) denotes the Legendre symbol, and d denotes the least positive quadratic non-residue (mod p) that is, the least positive integer for which (d/p) — 1 . The problem of an upper bound estimate for d originates in the work of Vinogradov [10], where he gave the estimate d < p
Detection of circumstellar nitric oxide

Aims. During a full line survey towards IRC +10420 in the 3 and 1 mm bands, we detected the emission of circumstellar nitric oxide for the first time. We aim to study the formation of NO and to confirm the enrichment of nitrogen expected for the most massive, evolved stars predicted by the hot bottom burning process. Methods. We counted on a detailed model of the structure and kinematics of the molecular gas around IRC u +10420. In addition, we used a chemical model to derive the NO abundance profile. We modified the initial nitrogen abundance in order to fit the observed NO profiles. These synthetic profiles were obtained using an LVG radiative transfer code. Results. We have detected NO in a circumstellar envelope for the first time, along with a variety of N-rich molecules, which in turn shows that IRC +10420 presents a N-rich chemistry. Furthermore, we have found that to reproduce the observed NO line profiles, the initial abundance of nitrogen in the chemical model has to be increased by a factor 20 with respect to the values of the standard O-rich stars.
Matrix completion via an alternating direction method

The matrix completion problem is to complete an unknown matrix from a small number of entries, and it captures many applications in diversified areas. Recently, it was shown that completing a low-rank matrix can be successfully accomplished by solving its convex relaxation problem using the nuclear norm. This paper shows that the alternating direction method (ADM) is applicable for completing a low-rank matrix including the noiseless case, the noisy case and the positive semidefinite case. The ADM approach for the matrix completion problem is easily implementable and very efficient. Numerical comparisons of the ADM approach with some state-of-the-art methods are reported.
X-ray line emission from the supernova remnant G292.0 + 1.8

The Solid State Spectrometer on the Einstein Observatory has detected line emission from Mg, Si and S in the thermal X-ray spectrum of the supernova remnant G292.0 + 1.8. An over-abundance of sulfur and a probable under-abundance of iron relative to their solar values is indicated by the data. The X-ray and optical data for this object support an interpretation of emission originating in ejecta from the comparatively recent explosion of a massive (about 20-solar-mass) progenitor star.
The formation of vertical Vortices in the convective boundary layer

A study of the dynamical formation mechanisms of atmospheric boundary‐layer vortices is being conducted. These vortices are typically manifest as dust devils although there is evidence that they exist with some frequency in the absence of visible flow tracers. For example, in 1997 MacPherson and Belts pointed out instrument observations of invisible boundary‐layer vertical vortices over the boreal forest. Several possible mechanisms for vortex formation under a variety of different dynamical regimes are described. Most observational investigators have reported that dust devils form in environments characterized by low wind speeds. The most intriguing unknown is the source of vorticity for the formation of vortices for convection in the absence (or near absence) of mean winds. Vertical vortex formation in convection without a mean shear has not often been documented in laboratory or numerical simulations.
Studies on error propagation for certain nonlinear approximations to hyperbolic equations: discontinuities in derivatives

The accuracy of numerical approximations to piecewise smooth solutions of hyperbolic partial differential equations is greatly influenced by the presence of singularities in the solution. In the presence of coupling (through lower-order terms or variable coefficients), high-order numerical approximations can lose accuracy in large regions, where the analytical solution is known to be smooth, due to the spreading of the errors that the singularities introduce in the computation.This phenomenon, which has been analyzed in the past fifteen years for a number of classical linear methods, is studied here for numerical approximations obtained with nonlinear essentially non oscillatory (ENO) schemes. The study of the local rate of convergence allows for the identification of the necessary techniques to reduce the spread of errors and to avoid the accuracy loss of the computed approximations.The techniques developed can be applied to nonlinear hyperbolic partial differential equations and systems to sharpen the r.
Percolation model of immiscible displacement in the presence of buoyancy forces

We consider the quasistatic displacement of a nonwetting fluid by a wetting one in a porous medium in the presence of buoyancy forces. A simple percolation model of this process is presented and analyzed both theoretically and by Monte Carlo simulation. It is shown that the fact that percolation is a critical phenomenon, with diverging correlation length at the critical point, has a significant effect on the physics of the system, in particular on the dependence of nonwetting phase residual saturation on the density contrast between the phases. An extension of these ideas to the case where the pressure field is generated by viscous rather than buoyancy forces is suggested.
Large-Eddy Simulation of Wake and Boundary Layer Interactions Behind a Circular Cylinder

Large-eddy simulations (LESs) of flow past a circular cylinder in the vicinity of a flat plate have been carried out for three different gap-to-diameter (G/D) ratios of 0.25, 0.5, and 1.0 (where G signifies the gap between the flat plate and the cylinder, and D signifies the cylinder diameter) following the experiment of Price et al. (2002, "Flow Visualization Around a Circular Cylinder Near to a Plane Wall, " J. Fluids Struct., 16, pp. 175―191). The flow visualization along with turbulent statistics are presented for a Reynolds number of Re = 1440 (based on D and the inlet free-stream velocity U ∞ ). The three-dimensional time-dependent, incompressible Navier―Stokes equations are solved using a symmetry-preserving finite-difference scheme of second-order spatial and temporal accuracy. The immersed-boundary method is employed to impose the no-slip boundary condition at the cylinder surface. An attempt is made to understand the physics of flow involving interactions of shear layers shed from the cylinder and the wall boundary layer. Present LES reveals the shear layer instability and formation of small-scale eddies apart from their mutual interactions with the boundary layer. It has been observed that G/D ratio has a large influence on the modification of wake dynamics and evolution of the wall boundary layer. For a low gap ratio, it is difficult to identify the boundary layer because of its strong interactions with the shear layers; however, a rapid transition to turbulence of the boundary layer, which is similar to bypass transition, is observed for a large gap ratio.
FLOW AND HEAT TRANSFER FOR THREE-DIMENSIONAL FLOW OVER AN EXPONENTIALLY STRETCHING SURFACE

This study analyzes the laminar boundary-layer flow and heat transfer characteristics of a steady, three-dimensional viscous fluid driven by a horizontal surface stretched exponentially in two lateral directions. The simulations in this study assume that the surface temperature is also distributed exponentially and reduce the governing equations to a set of ordinary differential equations using a similarity transformation. This study develops a numerical procedure that combines the Ackroyd method and Runge-Kutta integration scheme to solve the transformed equations. Results show that heat transfer characteristics depend strongly on the stretching ratio, temperature exponent, and Prandtl number.
Symmetric Merge and Local Instability: Evidence from Split Topics

In this paper, I argue against the standard analysis of so-called split topics in German as discontinuous noun phrases (van Riemsdijk 1989). Building in part on Fanselow 1988, I show that the construction rather involves two morphosyntactically autonomous nominal constituents that are predicatively related in underlying form. This predication is syntactically unstable, however. Merge of two XPs within a single argument or adjunct position yields a symmetric structure for which no label (“head”) can be detected by Minimal Search (“for any syntactic object {α,β},α is the head if α is a lexical item”; see Chomsky 2008). Therefore, one of the two noun phrases must move at the phase level in order to render the structure asymmetric; in case the stranded noun phrase is elliptical, the impression of a discontinuous constituent arises. By providing a principled explanation for split topicalization in these terms, the analysis furnishes evidence for an architecture in which Merge applies freely (pace recent claims to the contrary, e.g., in Kayne 2010), and as an asymmetrizing device when applying internally (as movement), in the spirit of Moro 2000 and Chomsky 2013.
Production of Pions and Light Fragments at Large Angles in High-Energy Nuclear Collisions

Inclusive cross sections for production of ${\ensuremath{\pi}}^{+}$, ${\ensuremath{\pi}}^{\ensuremath{-}}$, $p$, $d$, $^{3}\mathrm{H}$, $^{3}\mathrm{He}$, and $^{4}\mathrm{He}$ have been measured at laboratory angles from 10\ifmmode^\circ\else\textdegree\fi{} to 145\ifmmode^\circ\else\textdegree\fi{} in nuclear collisions of Ne + Naf, Ne + Cu, and Ne + Pb at 400 MeV/nucleon, C + C, C + Pb, Ne + NaF, Ne + Cu, Ne + Pb, Ar + KCl, and Ar + Pb at 800 MeV/nucleon, and Ne + NaF and Ne + Pb at 2.1 GeV/nucleon. The production of light fragments in proton induced collisions at beam energies of 800 MeV and 2.1 GeV has also been measured in order to allow us to compare these processes. For equal-mass nuclear collisions the total integrated yields of nuclear charges are well explained by a simple participant-spectator model. For 800 MeV/nucleon beams the energy spectra of protons at c.m. 90\ifmmode^\circ\else\textdegree\fi{} are characterized by a "shoulder-arm" type of spectrum shape with an exponential falloff at high energies, whereas those of pions are of a simple exponential type. The inverse of the exponential slope, ${E}_{0}$, for protons is systematically larger than that for pions. This value of ${E}_{0}$ is larger for heavier-mass projectiles and targets. It also increases monotonically with the beam energy. The angular anisotropy of protons is larger than that of pions. The yield ratio of ${\ensuremath{\pi}}^{\ensuremath{-}}$ to total nuclear charge goes up with the beam energy, whereas the yields of composite fragments decrease. The ratio of low-energy ${\ensuremath{\pi}}^{\ensuremath{-}}$ to ${\ensuremath{\pi}}^{+}$, as well as that of $^{3}\mathrm{H}$ to $^{3}\mathrm{He}$, is larger than the neutron to proton ratio of the system. The spectrum shape of the composite fragments with mass number $A$ is explained very well by the $A\mathrm{th}$ power of the observed proton spectra. The sizes of the interaction region are evaluated from the observed coalescence coefficients. The radius obtained is typically 3-4 fm. The yield ratio of composite fragments to protons strongly depends on the projectile and target masses and the beam energy, but not on the emission angle of the fragments. These results are compared with currently available theoretical models.
Improved Generalized Estimating Equation Analysis via xtqls for Quasi–Least Squares in Stata

Quasi–least squares (QLS) is an alternative method for estimating the correlation parameters within the framework of the generalized estimating equation (gee) approach for analyzing correlated cross-sectional and longitudinal data. This article summarizes the development of qls that occurred in several reports and describes its use with the user-written program xtqls in Stata. Also, it demonstrates the following advantages of qls: (1) qls allows some correlation structures that have not yet been implemented in the framework of gee, (2) qls can be applied as an alternative to gee if the gee estimate is infeasible, and (3) qls uses the same estimating equation for estimation of β as gee; as a result, qls can involve programs already available for gee. In particular, xtqls calls the Stata program xtgee within an iterative approach that alternates between updating estimates of the correlation parameter α and then using xtgee to solve the gee for β at the current estimate of α. The benefit of this approach is that after xtqls, all the usual postregression estimation commands are readily available to the user.
Multidimensional Item Response Theory Modeling of Binary Data: Large Sample Properties of NOHARM Estimates

NOHARM is a program that performs factor analysis for dichotomous variables assuming that these arise from an underlying multinormal distribution. Parameter estimates are obtained by minimizing an unweighted least squares function of the first- and second-order marginal proportions. Here, large sample standard errors for restricted as well as rotated unrestricted factor solutions are given. Also a test of the goodness of fit of the model to the first- and second-order marginals of the contingency table is proposed. In a simulation study, it was found that for small models, accurate parameter estimates, standard errors, and goodness-of-fit tests can be obtained with as few as 100 observations. Furthermore, NOHARM estimates, standard errors, and goodness-of-fit tests are comparable to those obtained using a related LISREL procedure.
Combinatorial Applications of Hermite Polynomials

Let $C_1 ,C_2 , \cdots ,C_k $ be k finite sets of elements, where $n_i $ is the number of elements in $C_i (i = 1,2, \cdots ,k)$ and $\sum_{i = 1}^k {n_i } $ is even, $2S$ (say). In any arrangement of the elements into S disjoint pairs, we count the number of homogeneous pairs, i.e., those in which both numbers are from the same subset, $C_i $. We define such a pairing as even, odd or pure according as the number of homogeneous pairs is even, odd or zero respectively. The numbers of possible pairings of the different types are expressed as integrals involving Hermite polynomials, and these expressions are used both to derive new combinatorial results and also to provide combinatorial proofs of analytical formulae.
Learning from correlated examples in a perceptron

Using the replica method the authors investigate learning from correlated data in a perceptron. Both types of association-'spatial'-within each example, and 'semantic'-among the different ones-are considered for both Boolean and continuous weights and output functions. 'Spatial' correlations of data may significantly improve the learning properties, whereas the 'semantic' ones do not practically influence them.
The Electromagnetic Field of a Vertical Dipole on the Dielectric-Coated Imperfect Conductor

In this paper, the current and simple analytical formulas of the electromagnetic field generated by a vertical dipole on the surface of dielectric-coated imperfect plane conductor are derived. Especially, the model equation of the trapped surface wave are given and the trapped wave and lateral wave are analyzed carefully. Finally computations and discussions are carried out in several different cases.
The Bedrosian identity and homogeneous semi-convolution equations

We characterize a class of functions satisfying the classical Bedrosian identity or the circular Bedrosian identity by certain homogeneous semi-convolution equations. The structure of solutions of these equations is then studied using translation invariant subspaces of Hardy spaces and additive positive definite kernels. The obtained results provide some insight into the Bedrosian identity and a construction of intrinsic mode functions for the time-frequency analysis of nonlinear and nonstationary signals.
Regularized semiparametric model identification with application to nuclear magnetic resonance signal quantification with unknown macromolecular base‐line

Summary. We formulate and solve a semiparametric fitting problem with regularization constraints. The model that we focus on is composed of a parametric non‐linear part and a nonparametric part that can be reconstructed via splines. Regularization is employed to impose a certain degree of smoothness on the nonparametric part. Semiparametric regression is presented as a generalization of non‐linear regression, and all important differences that arise from the statistical and computational points of view are highlighted. We motivate the problem formulation with a biomedical signal processing application.
ZERODUR: new results on bending strength and stress corrosion

ZERODUR® strength data and information are required for the design of structures, which will be subject to mechanical loads throughout their lifetime or at least during some periods thereof such as lightweight mirrors for space telescopes. Comparison of data acquired twenty years ago with recent ones show astonishing reproducibility. An influence of the specimen preparation process on the width of the breakage stress distribution generally leading to higher values has been observed. New data are available for diamond grain D25 fine ground surface condition. The stress corrosion coefficient, an important parameter needed to calculate the long time behavior of structures subject to tensile stress in their surface has been determined from breakage data sets obtained with different stress load increase rates. Conditioning of ZERODUR® specimen with stress free storage under varying humidity and humidity exposure times has shown no influence on strength.