Miracle-dz/UniFAR-FTUs huggingface dataset:
Non‐WKB Alfvén waves in the solar wind

We treat, both analytically and numerically, small-amplitude, undamped, toroidal Alfven waves in a model of axisymmetric solar wind flow in which solar rotation is neglected. There is no restriction to WKB waves; the waves may have any frequency. By transforming in simple ways the equations governing the waves we are able to obtain exact formal solutions to the general time-dependent problem as well as to the Fourier-analyzed problem. We discuss the equations and their solutions in terms of coupled inward and outward propagating waves. One integral of the equations for the Fourier amplitudes is obtained; it relates the amplitudes of the ingoing and outgoing waves. The integral is a special case of a general law of conservation of wave action, which we show to hold for finite wavelengths. The statement of the conservation of wave action is shown to be analogous to the conservation of particle-antiparticle pairs in relativistic quantum theory. We obtain the condition required for WKB waves and show that it depends on the coupling of waves in a flowing medium. The solar wind problem is discussed in terms of the Fourier amplitudes. It is shown that there is a singularity in the equations, at the Alfven point, which determines physically acceptable solar wind solutions. A qualitative account of the amplitudes far from the sun is given based on an exact solution for a model with constant solar wind flow speed. A conservation equation for the wave energy is obtained, and the relations among the wave energy density, energy flux density, force, and acceleration are stated. Numerical solutions, based on realistic solar wind profiles, are given. We show that non-WKB waves with wave periods of about a day or two have somewhat greater wave energy densities, up to a factor of 2 or so, in the corona than do WKB waves with the same amplitude at 1 A.U. On the other hand, non-WKB waves of any wave period are no more effective in accelerating the plasma than are WKB waves; they are much less effective for wave periods of a day or more. We conclude that, for conditions actually existing in the corona, WKB estimates quite accurately account throughout the corona for the wave energy density, energy flux density, and wave acceleration of the plasma for Alfven waves with periods less than about 0.05, 1, and 0.01 day, respectively; the corresponding periods in the solar wind are about 1, 1, and 0.5 day.
Fisher information in generalized order statistics

A representation of the Fisher information in generalized order statistics in terms of the hazard rate of the underlying distribution function is derived under mild regularity conditions. This expression supplements results for complete, Type-II censored, and progressively Type-II censored data. As a byproduct, we find a hazard rate based representation for samples of k-records which apparently has not been known so far. Moreover, sufficient conditions for the validity of this representation in location and scale family settings are given. The result is illustrated by considering generalized order statistics based on logistic, Laplace, and extreme value distributions.
FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

We present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes.
OB association members in the ACT and TRC catalogues

The Hipparcos Catalogue contains members of nearby OB associations brighter than 12th magnitude in V. However, membership lists are complete only to magnitude V=7.3. In this paper we discuss whether proper motions listed in the ‘Astrographic Catalogue+Tycho’ reference catalogue (ACT) and the Tycho Reference Catalogue (TRC), which are complete to V∼10.5 mag, can be used to find additional association members. Proper motions in the ACT/TRC have an average accuracy of ∼3 mas yr−1. We search for ACT/TRC stars which have proper motions consistent with the spatial velocity of the Hipparcos members of the nearby OB associations already identified by de Zeeuw et al. These stars are first selected using a convergent-point method, and then subjected to further constraints on the proper-motion distribution, magnitude and colour to narrow down the final number of candidate members. Monte Carlo simulations show that the proper-motion distribution, magnitude, and colour constraints remove ∼97 per cent of the field stars, while at the same time retain more than 90 per cent of the cluster stars. The procedure has been applied to five nearby associations: the three subgroups of Sco OB2, plus Per OB3 and Cep OB6. In all cases except Cep OB6, we find evidence for new association members fainter than the completeness limit of the Hipparcos Catalogue. However, narrow-band photometry and/or radial velocities are needed to pinpoint the cluster members, and to study their physical characteristics.
FORWARD AND REVERSE CARLESON INEQUALITIES FOR FUNCTIONS IN BERGMAN SPACES AND THEIR DERIVATIVES

is satisfied. In the process, a simple proof of certain inequalities on derivatives of functions in HP is obtained (Section 3) as well as some information on interpolation sequences for LP (Section 5). Inequalities like (1.1) have already been used to provide information on Bergman-Toeplitz operators [L1] and are useful for obtaining representations of functions in Lp (Section 4, Theorem 4.6). The inequality which reverses the roles of A and m in (1.1) is relatively easy-even if an appropriate weighting factor is included with m (Theorem A below). It was obtained by Oleinik and Pavlov [OP] and independently (when p = q > 1) by Stegenga [S] and (with c = 0) Hastings [Ha]. The results of Oleinik and Pavlov (which are more general than Theorem A) were extended somewhat by Oleinik in [0]. Cima and Wogen [CW], using Stegenga's methods, proved the analogue of Theorem A in several variables. The methods of [L3] more or less supercede all these results.
Aspect Ratio Effect on Convective Heat Transfer of Radially Outward Flow in Rotating Rectangular Ducts

Experiments were conducted to investigate the effects of rotation and aspect ratio on the convective heat transfer of radially outward air flows in rotating rectangular ducts with a uniform wall heat flux by using fiberglass duct walls lined with separated film heaters. The duct hydraulic diameter, heater active length, and mean rotation radius were 4, 120, and 180 mm, respectively. Ranges of parameters were through-flow Reynolds number, 1,000–15,000; rotation number, 0–0.32; rotational buoyancy parameter, 0–1.2; and cross-sectional aspect ratio, 0.5, 1.0, and 2.0. The results showed that the higher the rotation number, the greater the enhancement ofthe heat transfer rate especially at the pressure side. The rotational buoyancy parameter decreases the heat transfer for low Re but enhances the heat transfer for high Re. The largest heat transfer enhancement is seen for AR = 1.0, and the enhancement for AR = 0.5 is greater than that for AR = 2.0.
Large magnetic‐field‐induced strains in Ni2MnGa single crystals

Strains of nearly 0.2% have been induced along [001] in unstressed crystals of Ni2MnGa with magnetic fields of 8 kOe applied at 265 K. These stains are associated with the superelastic motion of twin boundaries in the martensitic phase that is stable below about 274 K.
The diffusion approximation for tandem queues in heavy traffic

Consider a pair of single server queues arranged in series. (This is the simplest example of a queuing network.) In an earlier paper [2], a limit theorem was proved to justify a heavy traffic approximation for the (two-dimensional) equilibrium waiting-time distribution. Specifically the waiting-time distribution was shown to be approximated by the limit distribution F of a certain vector stochastic process Z. The process Z was defined as an explicit, but relatively complicated, transformation of vector Brownian motion, and the general problem of determining F was left unsolved. It is shown in this paper that Z is a diffusion process (continuous strong Markov process) whose state space S is the non-negative quadrant. On the interior of S, the process behaves as an ordinary vector Brownian motion, and it reflects instantaneously at each boundary surface (axis). At one axis, the reflection is normal, but at the other axis it has a tangential component as well. The generator of Z is calculated. It is shown that the limit distribution F is the solution of a first-passage problem for a certain dual diffusion process Z ∗. The generator of Z ∗ is calculated, and the analytical theory of Markov processes is used to derive a partial differential equation (with boundary conditions) for the density f of F. Necessary and sufficient conditions are found for f to be separable (for the limit distribution to have independent components). This extends slightly the class of explicit solutions found previously in [2]. Another special case is solved explicitly, showing that the density is not in general separable.
LITTLEWOOD–PALEY THEORY AND REGULARITY ISSUES IN BOLTZMANN HOMOGENEOUS EQUATIONS I: NON-CUTOFF CASE AND MAXWELLIAN MOLECULES

We use Littlewood–Paley theory for the analysis of regularization properties of solutions of the homogeneous Boltzmann equation. For non-cutoff Maxwellian molecules, we show that such solutions are smoother than the initial data. Although the recent and up to date results of Desvillettes and Wennberg10 assume much more general assumptions on the collision cross sections, our method seems to be simpler than those used earlier to show such properties and also applies to any weak solution.
On the Instability of Deflagration Fronts in White Dwarfs

We discuss the stability of a deflagration front in white dwarfs in the context of burning mechanisms for Type Ia Supernovae. It is shown that the basic characteristics of the instability of the deflagration front are different from those of Rayleigh-Taylor instability, on which the deflagration models rely. In view of this, together with results from two-dimensional simulations, we argue that the deflagration model needs reconsideration, as Rayleigh-Taylor instability cannot explain the required high flame speed required for producing an explosion similar to Type Ia Supernovae. On the other hand, the same arguments imply that delayed detonation is acceptable and that the transition to detonation must occur in the very low density regime, where good agreement between observations and numerical results is obtained
The HI Luminosity Function from ‘Blind’ Surveys

Abstract Recent neutral hydrogen (HI) surveys have detected enough sources to make initial predictions of the extragalactic HI luminosity function. These surveys provide useful pointers for the Parkes Multibeam Survey, highlighting various advantages and disadvantages of different observing and analysis procedures. The newest surveys are also large enough to permit some statistical tests of their completeness. The detection rates clearly fall short of what would be expected based on a simple propagation of errors, suggesting the need for further development of detection software. I suggest several procedures for determining the effective sensitivity of HI surveys. Applied to two recent Arecibo surveys, these suggest that the HI luminosity function may be much steeper than its optical counterpart, and that the Parkes surveys may detect a large number of low-mass sources.
Numerical Distribution Functions for Unit Root and Cointegration Tests

This paper employs response surface regressions based on simulation experiments to calculate distribution functions for some well-known unit root and cointegration test statistics. The principal contributions of the paper are a set of data files that contain estimated response surface coefficients and a computer program for utilizing them. This program, which is freely available via the Internet, can easily be used to calculate both asymptotic and finite-sample critical values and P-values for any of the tests. Graphs of some of the tabulated distribution functions are provided. An empirical example deals with interest rates and inflation rates in Canada. Copyright 1996 by John Wiley & Sons, Ltd.
Asymptotically matched sheath and presheath in a dense plasma

Asymptotically matched solutions for electron and ion density, electron and ion velocity, and electric potential are obtained in the boundary region of a dense low-temperature plasma adjacent to perfectly absorbing walls – walls that absorb, without reflection, incident electrons and ions. Leading-order composite solutions, valid throughout the boundary region, are constructed from solutions in three subdomains distinguished by different physical length scales: the geometric length, the ion mean free path and the Debye length. The composite solutions are used to assess the impact of electron–ion recombination in the ionization nonequilibrium region on sheath and presheath profiles, and on quantities evaluated at the wall. While, at leading order, the velocity profiles throughout the boundary region are not influenced by recombination, the density and potential profiles are significantly altered when recombination is included. These results show that the region of rapid change in these profiles lies closer to the wall when recombination is explicitly included in the model. The influence of recombination on the presheath potential, and consequently the wall potential, is found to scale as the natural logarithm of the recombination length. The broadening of the density profile results in a larger flux of ions accelerating through the sheath and impacting on the wall. The influence of recombination on the ion power flux to the wall is found to scale with the inverse recombination length. This scaling influences the prediction of surface erosion rates in technological applications that utilize these plasmas.
Large-scale coherent structures in the wake of axisymmetric bodies

The unsteady flow past a circular disk is studied with hot-wire and microphone probes positioned in planes normal to the axis of symmetry at 3 and 9 disk diameters down-stream. Both the fluctuating velocity and pressure signals are shown to be continuously dominated by large-scale coherent motions enveloping the wake flow as a whole. This suggests narrowband two-point space correlations as an experimental tool for describing spatial coherence and phase characteristics of the basically random signals. The specific symmetry imposed by the axisymmetric boundary conditions of the disk enables a decomposition of the large-scale flow phenomena into relatively simple elementary structures or modes. The resulting azimuthal constituents are quantified in terms of their respective magnitudes and individual power spectra. The capability of the approach to uncover characteristic features of turbulence as far as its large-scale domain is concerned is demonstrated by a comparison of the present results with certain remarkably different features found in earlier jet flow investigations: the m = 1 and m = 2 modes are found to clearly dominate in wakes whereas the m = 0 and m = 1 modes were dominant in jets in a relevant range of Strouhal numbers. These large-scale coherent structures are more than just an interesting flow phenomenon; they must have a tremendou back-reaction on rigid flow boundaries (particularly if these allow a vibrational response) and may give rise to specific feedback mechanisms. The analysing technique proposed for studying large-scale flow phenomena injets and wakes removes part of the randomness in the turbulent signals without artificially exciting or forcing them in one way or another. No conditional sampling of the naturally occurring fluctuations is required, either. The method may be applicable to other than strictly axisymmetric flow configurations, too.
A Lightning Data Assimilation Technique for Mesoscale Forecast Models

Abstract Lightning observations have been assimilated into a mesoscale model for improvement of forecast initial conditions. Data are used from the National Lightning Detection Network (cloud-to-ground lightning detection) and a Lightning Mapping Array (total lightning detection) that was installed in western Kansas–eastern Colorado. The assimilation method uses lightning as a proxy for the presence or absence of deep convection. During assimilation, lightning data are used to control the Kain–Fritsch (KF) convection parameterization scheme. The KF scheme can be forced to try to produce convection where lightning indicated storms, and, conversely, can optionally be prevented from producing spurious convection where no lightning was observed. Up to 1 g kg−1 of water vapor may be added to the boundary layer when the KF convection is too weak. The method does not employ any lightning–rainfall relationships, but rather allows the KF scheme to generate heating and cooling rates from its modeled convection. The.
Covariance of discounted compound renewal sums with a stochastic interest rate

Formulas have been obtained for the moments of the discounted aggregate claims process, for a constant instantaneous interest rate, and for a claims number process that is an ordinary or a delayed renewal process. In this paper, we present explicit formulas on the first two moments and the joint moment of this risk process, for a non-trivial extension to a stochastic instantaneous interest rate. Examples are given for Erlang claims number processes, and for the Ho–Lee–Merton and the Vasicek interest rate models.
Uncertainty Calculations in Pyranometer Measurements and Application

The uncertainty of pyranometer measurements should be traced back to the World Radiation Reference (WRR), a standard that is specified by the mean sensitivity of the World Standard Group (WSG). The WSG is build up by 7 primary standard pyrheliometers, operated at Davos, Switzerland. Analyzing the complete calibration chain for an individual field pyranometer, usually the uncertainty of its calibration constant is extracted as a unique figure depending on the calibration method. The common representation of the expanded uncertainty, specified by the manufacturer is global information on the accuracy of daily averages. For the use of pyranometers for e.g. test of solar energy components as solar collectors, this information on the global daily accuracy of the pyranometer is not sufficient. As the response of a solar collector to the irradiance shows nonlinearities, a more detailed analysis of the pyranometer uncertainties is necessary. This will be demonstrated for the analysis of the uncertainties of the test results — i.e. the collector coefficients and their uncertainties — and the resulting predictions of the energy gain by these devices. Ancillary information by the manufacturers will be used to discuss the uncertainty of individual measurements depending on e.g. ranges of those parameters that originate the uncertainties, depending on the geometry (incidence angle), ambient temperature and the sky conditions. Based on this information the inter-comparability of test performed at different times or with different instruments will be discussed.Copyright © 2006 by ASME
Applications of KO Displacement Theory to the Deformed Shape Predictions of the Doubly-Tapered Ikhana Wing

The Ko displacement theory, formulated for weak nonuniform (slowly changing cross sections) cantilever beams, was applied to the deformed shape analysis of the doubly-tapered wings of the Ikhana unmanned aircraft. The two-line strain-sensing system (along the wingspan) was used for sensing the bending strains needed for the wing-deformed shapes (deflections and cross-sectional twist) analysis. The deflection equation for each strain-sensing line was expressed in terms of the bending strains evaluated at multiple numbers of strain-sensing stations equally spaced along the strain-sensing line. For the preflight shape analysis of the Ikhana wing, the strain data needed for input to the displacement equations for the shape analysis were obtained from the nodal-stress output of the finite-element analysis. The wing deflections and cross-sectional twist angles calculated from the displacement equations were then compared with those computed from the finite-element computer program. The Ko displacement theory formulated for weak nonlinear cantilever beams was found to be highly accurate in the deformed shape predictions of the doubly-tapered Ikhana wing.
The Ionization Structure of the Narrow-Line Region of NGC 1068 and Its Relationship to the Extended Radio Emission

Hubble Space Telescope (HST)/WFPC2 imaging has been used to investigate the emission-line structure of the narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068 and its relationship to the extended radio emission. We find that the morphology and the ionization properties of the NLR of NGC 1068 are dominated by the interaction with the radio jet, in full agreement with similar results obtained for other Seyfert galaxies with extended radio emission. The emission lines originate in two distinct regions: a large-scale cocoon enveloping the northeastern radio lobe and a small-scale broken network of filaments and knots surrounding the radio jet. The material along the radio jet, although denser than the surrounding gas, is in a much higher ionization state than the remainder of the NLR. We believe that this requires the presence of a source of ionizing radiation that locally dominates over the nuclear emission, e.g., free-free emission from the gas heated by the interaction with the radio jet. At a distance of approximately 4'' (~300 pc) from the nucleus, corresponding to the transition in the radio structure from jetlike to lobelike, the ionization structure of the NLR shows a sharp and well-defined boundary between an inner low-ionization zone and an outer higher ionization zone. This ionization change is easily explained if there is a density increase where the jet enters the lobe, presumably due to the compression of the backflowing radio cocoon at the jet working surface. A color image reveals the presence of a nuclear dust lane projected onto the location of the hidden nucleus. Nuclear dust lanes appear to be ubiquitous in Seyfert 2 galaxies observed with HST and can be naturally associated with the material responsible for the obscuration of the active nucleus.