Miracle-dz/UniFAR-FTUs huggingface dataset:
High-velocity NaI and CaII absorption components observed towards the IC 443 SNR

We present high-resolution spectra (R 1: 8k m s 1 ) of the interstellar NaI and CaII interstellar absorption lines observed towards 4 early-type stars with distances of 900-1500 pc in the line-of-sight towards the IC 443 Supernova Remant (SNR). The spectra of two of these stars (HD 43582 and HD 254577) exhibit a very complex pattern of absorption with cloud components covering a total velocity range of 100 km s 1 to+50 km s 1 . The relative absorption strength of many of the higher velocity components is highly variable between these two stars, suggesting that the disturbed interstellar gas in this region possesses significant density gradients and/or large dierences in ionization and element depletion. In addition, we have detected three additional high-velocity components at Vhelio = 97:5, 84.0 and 67.6 km s 1 solely in their CaII lines, suggesting that the very highest velocity gas is more ionized and/or warmer than the lower velocity components or it has a highly variable level of gas phase element abundances. The column density ratios of NaI/CaII for the higher velocity cloud components are all<0.2, which is consistent with apprecia- ble levels of dust grain destruction due to interstellar shocks caused by interaction of the expanding SNR blast-wave with the ambient interstellar medium. The distance to IC 443 is confirmed at 1500 pc, which places the remnant at a similar distance to the Gem OB1 stellar association. Finally we note that the model of Chevalier (1999), in which the SNR is expanding into a clumpy interstellar medium, can best reproduce the observed patterns of both emission and absorption.
Are sawtooth oscillations of energetic plasma particle fluxes caused by periodic substorms or driven by solar wind pressure enhancements

[1] Energetic electron and proton fluxes measured by geosynchronous satellites often show sawtooth-like variations during magnetic storms. We examine whether the sawtooth oscillations and relevant magnetospheric-ionospheric disturbances are caused by periodic substorms or driven by a series of enhancements in the solar wind pressure. We show that there are significant differences between periodic substorms and solar wind-induced variations. The energetic fluxes at geosynchronous orbit may increase by orders of magnitude after each onset of periodic substorms and by 10–50% in response to a large solar wind pressure impulse. The sudden increases of the energetic fluxes during periodic substorms show significant time delays of 30–50 min at different longitudes/local times, indicating that the fluxes are injected on the nightside and then drift to the dayside. In contrast, the small flux increases caused by solar wind pressure enhancements occur almost simultaneously at all local times. The periodic substorms always have a strong spectrum peak at 2–3 hours, no matter whether the solar wind pressure and/or IMF have similar spectrum peaks. The nightside magnetospheric magnetic elevation angle shows a large (30–60°) increase at each onset of periodic substorms through dipolarization and a small (<10°) decrease in response to a solar wind pressure impulse. Each cycle of periodic substorms can cause a deviation of 40–60 nT in the midlatitude geomagnetic field; the midlatitude geomagnetic deviations caused by solar wind pressure enhancements are proportional to the square root of the pressure change. The increase of the polar cap index caused by substorms is ∼4 times that caused by solar wind pressure enhancements. We conclude that the sawtooth-like flux oscillations represent flux injections during periodic substorms and that the period of substorms is determined by the magnetosphere.
Flexible Discriminant Analysis by Optimal Scoring

Abstract Fisher's linear discriminant analysis is a valuable tool for multigroup classification. With a large number of predictors, one can find a reduced number of discriminant coordinate functions that are “optimal” for separating the groups. With two such functions, one can produce a classification map that partitions the reduced space into regions that are identified with group membership, and the decision boundaries are linear. This article is about richer nonlinear classification schemes. Linear discriminant analysis is equivalent to multiresponse linear regression using optimal scorings to represent the groups. In this paper, we obtain nonparametric versions of discriminant analysis by replacing linear regression by any nonparametric regression method. In this way, any multiresponse regression technique (such as MARS or neural networks) can be postprocessed to improve its classification performance.
Dijet Production by Color-Singlet Exchange at the Fermilab Tevatron

We report a new measurement of dijet production by color-singlet exchange in p{ovr p} collisions at {radical}(s)=1.8 TeV at the Fermilab Tevatron. In a sample of events with two jets of transverse energy E{sup jet}{sub T}{gt}20 GeV , pseudorapidity in the range 1.8{lt}{vert_bar}{eta}{sup jet}{vert_bar}{lt}3.5 , and {eta}{sub 1}{eta}{sub 2}{lt}0 , we find that a fraction R=[1.13{plus_minus}0.12(stat){plus_minus} 0.11(syst)]{percent} has a pseudorapidity gap within {vert_bar}{eta}{vert_bar}{lt}1 between the jets that can be attributed to color-singlet exchnage. The fraction R shows no significant dependence on E{sup jet}{sub T} or on the pseudorapidity separation between the jets. {copyright} {ital 1998} {ital The American Physical Society}
A convection scheme for data assimilation: Description and initial tests

A new simplified parametrization of subgrid‐scale convective processes has been developed and tested in the framework of the ECMWF Integrated Forecasting System for the purpose of variational data assimilation, singular vector calculations and adjoint sensitivity experiments. Its formulation is based on the full nonlinear convection scheme used in ECMWF forecasts, but a set of simplifications has been applied to substantially improve its linear behaviour. These include the specification of a single closure assumption based on convective available potential energy, the uncoupling of the equations for the convective mass flux and updraught characteristics and a unified formulation of the entrainment and detrainment rates. Simplified representations of downdraughts and momentum transport are also included in the new scheme.
The Discovery of Photospheric Phosphorus and Iron in the Far Ultraviolet Spectroscopic Explorer Spectrum of the Hot DA White Dwarf GD 394

We report the discovery of the photospheric P V 3s(2S)-3p(2Po) transitions and Fe III 3d6(5D)-3d5(6S)4p(5Po) transitions detected in the far-UV spectrum of the hot hydrogen-rich white dwarf GD 394. The spectrum was obtained with the Far Ultraviolet Spectroscopic Explorer using the large aperture. The spectrum covers a wavelength range of 910-1180 Å at a resolution of λ/Δλ ~ 15,000. The presence of photospheric phosphorus and iron is the first firm detection of heavy elements other than silicon in the photosphere of GD 394. This detection confirms Extreme Ultraviolet Explorer observations, which show evidence of heavy elements in the photosphere of GD 394 with relatively low individual abundances. The spectrum reveals also a host of photospheric Si III and Si IV features.
Transport modelling in coastal waters using stochastic differential equations

In this thesis, the particle model that takes into account the short term correlation behaviour of pollutants dispersion has been developed. An efficient particle model for sediment transport has been developed. We have modified the existing particle model by adding extra equations for the suspension using a probabilistic concepts (the Poisson distribution function) to determine the actual number of particles to suspend in each cell. The deposition is modelled by an exponential decaying ordinary differential equation. In order to get accurate results from Monte Carlo simulations of sediment transport, a large number of particles is often needed. However, computation time in a particle model increases linearly with the number of particles. Thus, we have developed a high performance particle model for sediment transport by considering three different sediment suspension methods. Parallel simulation experiments are performed in order to investigate the efficiency of these three methods. We conclude that the second method is the best method on distributed computing systems (e.g., a Beowulf cluster), whereas the third maintains the best load distribution. Using variable time stepping to integrate the particle track in this thesis, has also proved to be efficient.
X-ray spectroscopy of the cluster of galaxies PKS 0745-191 with XMM-Newton

We present the results from XMM-Newton observations of the cluster of galaxies PKS 0745-191. The spatially resolved spectra from the European Photon Imaging Cameras ( both EPN and EMOS) can be fitted with a single temperature thermal plasma model when the interstellar column density is closer to the lower limit of the range allowed by observations. Alternatively, a two-component model can be fitted to the spectra from the inner region for slightly higher values of N-H. The temperature profile shows a drop in the center of the cluster, from about 8 keV at radii larger than similar to350 kpc to about 4 keV at the center, indicating that the gas in the central region is cooling. The total cooling flow rate inferred from the spectral data is only 364(-94)(+97) M-circle dot yr(-1), however, much smaller than the previously obtained value. The metal abundance is found to decrease from 0.5 in solar units at the center to about 0.2 at a radius of similar to300 kpc. Deprojected spectra are also presented, which show a result similar to the projected spectra. The location of the X-ray emission peak is also the site of extended radio emission. Inspection of the higher resolution Chandra image of the cluster shows enhanced X-ray emission about 3" west of the center where also the radio emission is elongated. We explore possible implications on the interaction between the radio lobes and the intracluster plasma. Assuming that the gas is in hydrostatic equilibrium with the cluster potential, we find a total mass of about 1.18 +/- 0.04 x 10(13) M-circle dot within the critical radius of the observed gravitational arc, which is a factor similar to2 lower, however, than that from optical lensing. We also calculated the gas mass fraction profile up to 0.63 r(vir) and obtained a mean gas mass fraction f(gas) = 0.22 +/- 0.02.
Small-sample properties of the maximum likelihood estimator in the first-order moving average model

SUMMARY In this paper we discuss finite sample properties of the maximum likelihood estimator 0 in the first-order moving average model. We give a theoretical explanation for the concentration of 0 values at the invertibility boundary. We derive the exact distribution of 0 for sample size n= 2 which is found to be of mixed type. For general n we give approximations for pr (0 = 1).
Cylinder loading in transient motion representing flow under a wave group

There are a great many studies that investigate the force on bodies in periodic oscillatory motions, but almost no studies that focus on the kinds of fluid loading that are of great relevance to offshore structure designers; namely, the problem of a cylinder subjected to the forces from ocean wave groups, especially those of large amplitude. In this study, we move a vertical circular cylinder in non-periodic horizontal orbital motion through stationary fluid, in a towing tank at Re≲1.15×104. The motion is chosen to represent the relative fluid motion incident upon a horizontal cylinder with its axis aligned parallel to the crest of a large ocean wave group, as defined by the ‘NewWave’ formulation. The vector form of the well-known Morison equation provides a good representation of the measured forces. By measuring the force components in the radial and azimuthal directions, we clearly demonstrate that the presence of vigorous force fluctuations at a higher frequency than the orbital motion are associated with vortex shedding that is otherwise masked by the choice of coordinates. We find vortex frequencies comparable with those for flow past fixed bodies and a ‘transverse’ force magnitude similar to the fixed flow case at the same average speed. Finally, we show that by retaining only an azimuthal (constant) drag coefficient term to represent the fluid loading throughout the wave group orbits, the resolved X- and Y-force fluctuations agree well with measured forces. This demonstrates that we can obtain a reasonable estimate of time-varying forces using a single term. It is expected that such a simple force representation will become less effective in shallower fluids and for smaller wave amplitudes relative to body size.
Hybrid magnetic attitude control gain selection

Abstract For spacecraft in low Earth orbits, attitude control via the torques provided by the geomagnetic field is an attractive option. Recent research has demonstrated that asymptotic pointing of attitude setpoints is possible using a linear combination of Euler parameter and angular velocity feedback. However, given the time-varying nature of the magnetic field, the size of the gains leading to stability is restricted. The present work looks at a hybrid scheme consisting of magnetic control using on-board dipole moments and an independent three-axis actuation scheme (i.e. reaction wheels or thrusters). A stability analysis is presented using passivity concepts that shows that the limitation on magnetic control gains can be removed if a minimum level of three-axis actuation augments the magnetic scheme.
Assessment of regularized delta functions and feedback forcing schemes for an immersed boundary method

We present an improved immersed boundary method for simulating incompressible viscous flow around an arbitrarily moving body on a fixed computational grid. To achieve a large Courant–Friedrichs–Lewy number and to transfer quantities between Eulerian and Lagrangian domains effectively, we combined the feedback forcing scheme of the virtual boundary method with Peskin's regularized delta function approach. Stability analysis of the proposed method was carried out for various types of regularized delta functions. The stability regime of the 4‐point regularized delta function was much wider than that of the 2‐point delta function. An optimum regime of the feedback forcing is suggested on the basis of the analysis of stability limits and feedback forcing gains. The proposed method was implemented in a finite‐difference and fractional‐step context. The proposed method was tested on several flow problems, including the flow past a stationary cylinder, inline oscillation of a cylinder in a quiescent fluid, and transverse oscillation of a circular cylinder in a free‐stream. The findings were in excellent agreement with previous numerical and experimental results. Copyright © 2008 John Wiley & Sons, Ltd.
THRESHOLD VARIABLE SELECTION IN OPEN‐LOOP THRESHOLD AUTOREGRESSIVE MODELS

An open-loop threshold autoregressive model is defined as The main difficulty for building such a model is that the threshold variable Zt is usually unknown. In practice, there may exist many possible candidates for the threshold variable Zt. It is difficult and tedious, if not impossible, to search for the best among all the candidates using standard model selection procedures. In this paper, we introduce a digression concept and propose two simple algorithms to classify the observations without knowing the threshold variable. The classification is then used with several graphical procedures to search for the most suitable threshold variable. Simulated and real examples are included to illustrate the proposed procedures.
CONE BEAM RECONSTRUCTION WITH SOURCES ON A CURVE

An inversion procedure is developed for reconstructing a function of compact support in $\mathbb{R}^3 $ from its divergent beam x-ray transform with sources on a curve. The results apply to many curves not satisfying the conditions of Tuy [SIAM J. Appl. Math., 43 (1983), pp. 546–552), for example, planar circles of sufficiently large radius. In some cases, estimates in Sobolev norms are established for the inversion operator.
Dynamic phase transitions in the kinetic mixed spin-1/2 and spin-5/2 Ising model under a time-dependent oscillating magnetic field

We calculate the dynamic phase transition (DPT) temperatures and present the dynamic phase diagrams in the kinetic mixed spin-1/2 and spin-5/2 Ising model under the presence of a time-dependent oscillating external magnetic field. We employ the Glauber transition rates to construct the set of mean-field dynamic equations. The time variation of the average magnetizations and the thermal behavior of the dynamic magnetizations are investigated, extensively. The nature (continuous or discontinuous) of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. The DPT points are obtained and the phase diagrams are presented in two different planes. Phase diagrams contain four fundamental phases and three coexistence or mixed phases, which strongly depend on interaction parameters. The phase diagrams are discussed and a comparison is made with the results of the other mixed spin Ising systems.
Experimental and numerical investigation of 2-D backward-facing step flow

Abstract Results of experimental and numerical investigations of air flows over a two-dimensional backward-facing step are presented. The lengths of separation and reattachment on the upper and lower walls were measured nonintrusively using closely spaced, multi-element hot-film sensor arrays for Re≤3000 and expansion ratios of 1·17 and 2·0. The hot-film sensor measurements are in good agreement with the present as well as previous numerical predictions. It is anticipated that this measurement capability will provide a practical means for the study of unsteady flow phenomena with flow separation as well.
On the asymptotics of meromorphic solutions for nonlinear Riemann–Hilbert problems

This paper is devoted to a global existence theorem of meromorphic solutions of the form Z(z)=Zo(z)+R(z) of a nonlinear Riemann–Hilbert problem (RHP) for multiply connected domains Gq(q[ges ]1), where Zo(z) is the singular part of the solution, R(z) is the regular part which is a holomorphic solution of some appropriate nonlinear RHP for Gq(q[ges ]1). Under appropriate conditions on the characteristics of both the singular part Zo(z) (number of poles) and regular part (winding number) we prove the existence of meromorphic solutions Z(z) of the form Z(z)=Zo(z)+R(z). The proof is based on a special construction of the singular part Zo(z) and an adequate formulation of Newton's method for the regular part R(z).
On the Non-existence of Unbounded Domains of Normality of Meromorphic Functions

provided that f−2 ∞ contains at least three distinct points, and all of the f n z are analytic on N f . It is well known that N f is open and has the property of complete invariance under f , that is, z ∈ N f if and only if f z ∈ N f . Let U be a component of N f ; then f n U ⊆ Un, where Un is a component of N f . If, for a smallest integer p > 0 f p U ⊆ U , then U is said to be a periodic component of period p. In particular, if p = 1, then U is called invariant. If, for some integer n ≥ 1 Un is a periodic, while U is not periodic, then U is called preperiodic. If U is a periodic component of period p and there exists a ∈ ∂U ∪ ∞ such that f z → a in U as n → ∞, and f z is not defined at z = a, then U is called a Baker domain. Furthermore, let U0 U1 Up−1 be a periodic cycle of Baker domains,
Recent advances in photonic integrated circuits

Some recent advances in photonic integrated circuits are presented, including an InP-based monolithically integrated optical channel monitor, an arrayed waveguide grating (AWG) triplexer and a novel design of polarization insensitive AWGs. The optical channel monitor comprises a flat-field echelle grating and a slab photodetector array. The channel passband is flattened and widened without loss penalty. The shape of the slab waveguide detectors and the layer structure are optimized to obtain low crosstalk and low polarization dependence. It also has a smaller size due to the elimination of output waveguides. For triplexers in fiber access networks, a cross-order AWG design is proposed to overcome the device layout difficulty due to the wide spectral range of the wavelength channels. The spectral periodicity of the grating is utilized to reduce the free spectral range requirement. Consequently, the AWG can operate at a higher diffraction order with a smaller overall size. Finally, a novel design of a polarization insensitive arrayed waveguide grating is presented. Unlike conventional AWGs where the optical path length difference is obtained only in the arrayed channel waveguides, we design the star coupler regions according to Rowland circle construction with an oblique incidence/diffraction angle. As a result, the optical path length difference is produced in both the channel waveguides and the slab waveguide regions. By using the birefringence difference between the channel waveguide and the slab waveguide, a polarization dispersion compensated AWG is realized without any additional fabrication step.
Critical levels and mixing layers induced by convectively generated gravity waves during CEPEX

We study data from the Central Equatorial Pacific Experiment, in particular the soundings providing temperature, pressure, wind and ozone profiles, and we link them to the large‐scale conditions deduced from the analyses of the European Centre for Medium‐Range Weather Forecasts. to the west of the date line, the mean wind shows a strong shear at the tropopause between the easterlies of the upper troposphere and the westerlies of the lower stratosphere. These are conditions propitious to the formation of critical levels for quasi‐stationary gravity waves generated by deep convection. the measured wind profiles show the main characteristics of the encounter of a wave with its critical level and, in the ozone and potential‐temperature profiles, the existence of a conspicuous mixing layer in the vicinity of this critical level. Our interpretation that the mixing layer is a consequence of the critical level is supported by numerical simulations with a nonlinear time‐dependent two‐dimensional model. the occurrence of a mixing layer in the tropopause structure seems to be characteristic of large‐scale equatorial convective areas during westerly phases of the quasi‐biennial oscillation.
Different temperature-dependent local displacements in the underdoped and overdoped La2 − xSrxCuO4 system

Cu K-edge extended X-ray absorption fine-structure (EXAFS) measurements have been used to study the temperature-dependent local structure of the underdoped and overdoped superconducting La2 − xSrxCuO4 system. The Debye-Waller factor of the in-plane Cu-O bonds has been used as an order parameter to measure the local displacements, revealing an anomalous behavior for the underdoped case while the overdoped system shows a negligible change as a function of temperature. The results provide an evidence for a close relationship between local Cu-O displacements, electron-lattice interaction and charge inhomogeneity in the copper oxide superconductors.
Binary sequences with good aperiodic autocorrelation functions obtained by neural network search

Binary sequences having good aperiodic autocorrelation functions (ACFs) with low sidelobes have found many applications. However, few good binary sequences are available for large sequence lengths. Apart from the well-known Barker sequences, the best possible sequences up to a length of 48 have been obtained essentially by an exhaustive search. The authors present binary sequences up to a length of 100 with good aperiodic ACFs, derived via a neural network approach.