Miracle-dz/UniFAR-FTUs huggingface dataset:
Convergence analysis of recursive identification algorithms based on the nonlinear Wiener model

Recursive identification algorithms, based on the nonlinear Wiener model, are presented. A recursive identification algorithm is first derived from a general parameterization of the Wiener model, using a stochastic approximation framework. Local and global convergence of this algorithm can be tied to the stability properties of an associated differential equation. Since inversion is not utilized, noninvertible static nonlinearities can be handled, which allows a treatment of, for example, saturating sensors and blind adaptation problems. Gauss-Newton and stochastic gradient algorithms for the situation where the static nonlinearity is known are then suggested in the single-input/single-output case. The proposed methods can outperform conventional linearizing inversion of the nonlinearity when measurement disturbances affect the output signal. For FIR (finite impulse response) models, it is also proved that global convergence of the schemes is tied to sector conditions on the static nonlinearity. In particular, global convergence of the stochastic gradient method is obtained, provided that the nonlinearity is strictly monotone. The local analysis, performed for IIR (infinite impulse response) models, illustrates the importance of the amplitude contents of the exciting signals. >
Comments on the use of the force mode in atomic force microscopy for polymer films

Atomic force microscopy (A.F.M.) was first described as a powerful technique for studying insulating, hard surfaces. Since then, it has also been considered as an appropriate technique for investigating, at a submicromic scale, elastic and viscoelastic properties of soft materials as polymer films. An attempt is made to show how macroscopic models can be fruitfully employed in order to interpret the force curves obtained in AFM on polymer films. Through an analysis of the slope variation and the way the instability occurs at the tip‐sample contact, it is shown that a macroscopic approach is a useful way to explain most of the features of the force curves. Furthermore the importance is underlined of the initial conditions. It is shown that for polymer samples which have a stiffness within the range of the probe one, drastic changes of the force curve shape can occur when the initial conditions vary. Finally, this approach should allow one to clarify the conditions for which the macroscopic approach fails.
Abundances in the Metal‐poor Common Proper Motion Star BD +00°2058A

Like two other metal‐poor, late‐type field stars showing odd abundance ratios suggestive of accreted origin, BD +00°2058A has a substantial apogalactocentric distance, reaches a large maximum height above the Galactic plane, and is a member of a common proper motion system. To examine whether such wide pairs might have a common origin in accreted subsystems, we present detailed abundances in BD +00°2058A derived from high signal‐to‐noise, high‐resolution optical spectroscopy. Using spectroscopically derived parameters, we find [Fe/H] = -1.16 ± 0.07, a factor of 2–4 larger than previous (but less direct) estimates. We find the α‐element, iron‐peak, and n‐capture abundances to be unremarkable compared with other field stars of similar [Fe/H]. The derived Li abundance, log N(Li) = 2.53, is large compared with otherwise similar stars; the normal n‐capture abundances and upper limits to6Li/7Li provide no evidence of Li enrichment from Li‐rich asymptotic giant branch star material or spallation. Interestingly, the [C/Fe] and [Na/Fe] ratios appear to be ∼0.3 dex lower and higher, respectively, than otherwise similar stars. This might point to Li enrichment by contaminating material having undergone “cool bottom processing,” but the lack of radial velocity variations provides no evidence of a close companion. Comparison with theoretical isochrones suggests a distance of 150 pc, which is in better agreement with two previous studies’ estimates of the distance of the fainter wide companion; kinematically based population classifications based on this distance are ambiguous. Finally, we draw attention to the importance of different, but reasonable, choices of Fe i gf‐values in our (and other) analyses.
Recommendations and best practice for the current state of the art in turbulence modelling

The purpose of this article is to offer some insights, suggestions and recommendations on usage of current statistical models of turbulence. The issues discussed have arisen during several decades' worth of combined research experience and through direct support of numerous commercial computational fluid dynamics (CFD) customer projects covering a broad range of aerospace, automotive, marine and manufacturing applications. The discussions and ideas presented pertain to how existing algorithms and phenomenological models of turbulence can best be used with current computer hardware.
Advection, moistening, and shallow‐to‐deep convection transitions during the initiation and propagation of Madden‐Julian Oscillation

Using observations from the 2011 AMIE/DYNAMO field campaign over the Indian Ocean and a high‐resolution regional model simulation, the processes that lead to the rapid shallow‐to‐deep convection transitions associated with the initiation and eastward propagation of the Madden‐Julian Oscillation (MJO) are examined. By tracking the evolution of the depth of several thousand individual model simulated precipitation features, the role of and the processes that control the observed midtropospheric moisture buildup ahead of the detection of deep convection are quantified at large and convection scales. The frequency of shallow‐to‐deep convection transitions is found to be sensitive to this midlevel moisture and large‐scale uplift. This uplift along with the decline of large‐scale drying by equator‐ward advection causes the moisture buildup leading to the initiation of the MJO. Convection scale moisture variability and uplift, and large‐scale zonal advection play secondary roles.
Wavelet multipliers and signals

Abstract The Schatten-von Neumann property of a pseudo-differential operator is established by showing that the pseudo-differential operator is a multiplier defined by means of an admissible wavelet associated to a unitary representation of the additive group Rn on the C*-algebra of all bounded linear operators from L2(Rn) into L2(Rn). A bounded linear operator on L2(R) arising in the Landau, Pollak and Slepian model in signal analysis is shown to be a wavelet multiplier studied in this paper.
Mean estimating equation approach to analysing cluster-correlated data with nonignorable cluster sizes

Most methods for analysing cluster-correlated biological data implicitly assume the ignorability of cluster sizes. When this assumption fails, the resulting inferences may be asymptotically invalid. Hoffman et al. (2001) proposed a simple but computationally intensive method, based on a large number of within-cluster resamples and associated separate estimating equations, that leads to asymptotically valid inferences whether the cluster sizes are ignorable or not. We study a simple method, based on a single inverse cluster size-weighted estimating equation, that avoids resampling and yet leads to asymptotically valid inferences. Simulation results are presented to assess the performance of the proposed method. We also propose Wald tests for ignorability of cluster sizes. Copyright 2005, Oxford University Press.
High-spectral-purity laser system for the AURIGA detector optical readout

We describe a low-frequency-noise laser system conceived for the readout of small mechanical vibrations. The system consists of a Nd:YAG source stabilized to a high-finesse Fabry–Perot cavity and achieves the best performance in the range 1–10 kHz with a minimum residual noise of 4×10-3 Hz/Hz. We perform an extended characterization of the frequency stability by means of an independent optical cavity and we also measure the residual fluctuations after transmission through an optical fiber. Our apparatus is optimized for use in an optical readout for the gravitational wave detector AURIGA, where a laser system with the characteristics reported here will allow an improvement of one order of magnitude in the detector sensitivity.
The response of bora‐type flow to sea surface temperature

A non‐linear, two‐dimensional, hydrostatic, incompressible numerical model with a higher‐order turbulence closure scheme is used to study the effect of sea surface temperature on the severe downslope wind called bora at the Adriatic coast. A non‐linear large‐amplitude mountain wave is generated and is broken beneath and within its critical layer, due to resonant tuning between the initially single‐layer atmosphere and the terrain. The tuning is governed by the Froude number. A qualitative and sometimes quantitative analogy exists between the wave‐breaking (unsteady, stratified) flow and the hydraulic jump (steady, two‐layer flow). It is also known that the strongest Adriatic bora appears during the winter season, when the sea surface temperature is typically larger than the ground surface temperature.
Normal Goodness-of-Fit Tests for Multinomial Models with Large Degrees of Freedom

Abstract Goodness-of-fit tests for independent multinomials with parameters to be estimated are usually based on Pearson's X 2 or the likelihood ratio G 2. Both are included in the family of power-divergence statistics SD λ. For increasing sample sizes each SD λ has an asymptotic X 2 distribution, provided that the number of cells remains fixed. We are dealing with an increasing-cells approach, where the number J of independent multinomials increases while the number of classes for each multinomial and the number of parameters remain fixed. Extending results on X 2 and G 2, the asymptotic normality of any SD λ is obtained for increasing cells. The corresponding normal goodness-of-fit tests discussed here apply for models with large degrees of freedom with no restrictions imposed on the sizes N j of each multinomial, allowing large as well as small expectations (sparse data) within each cell. The asymptotic expectation and variance of SD λ are easy to compute for Pearson's X 2 and simplify considerably for.
Student interpretation of the signs of definite integrals using graphical representations

Physics students are expected to apply the mathematics learned in their mathematics courses to physics concepts and problems. Few PER studies have distinguished between difficulties students have with physics concepts and those with either mathematics concepts and their application or the representations used to connect the math and the physics. We are conducting empirical studies of student responses to mathematics questions dealing with graphical representations of (single-variable) integration. Reasoning in written responses could roughly be put into three major categories related to particular features of the graphs: area under the curve, position of the function, and shape of the curve. In subsequent individual interviews, we varied representational features to explore the depth and breadth of the contextual nature of student reasoning, with an emphasis on negative integrals. Results suggest an incomplete understanding of the criteria that determine the sign of a definite integral.
An analysis of 2MASS near-infrared photometry for galactic planetary nebulae

The recently published 2MASS all-sky infrared survey includes JHK S photometry of over 300 million sources. It also provides sizes and aspect ratios for the ∼0.55 per cent of objects that appear in the extended-source catalogue. Although most of these detections correspond to galaxies, stars, H II regions, young stellar objects, reflection nebulae and so forth, a number of them also appear to correspond to galactic planetary nebulae (PNe). We have used this survey to determine the near-infrared properties of some 325 known galactic PNe. We shall show that most of the extended PNe possess a highly restrictive range of indices (J - H) o and (H - K S ) 0 ; much smaller, in fact, than has been determined in previous surveys of such outflows. There are also a large number of sources where emission is dominated by the central-star continua, as well as perhaps cases where H 2 S(1) emission is detectable within the K S band. Symbiotic type sources stand out as a separate category of outflow, as has been noted on several previous occasions. However, the correlation between the He + /H + ratio and (J - H) 0 appears weaker than determined before. We note that K S -band dimensions θ KS are often in close accord with their radio and/or visual counterparts. However, we also point out that certain sources appear to be significantly larger or smaller at NIR wavelengths. Similarly, we find that the aspect ratios r of larger sources are often in conflict with values measured at radio and/or visual wavelengths. We discuss possible reasons for the disparities in r and θ KS . Finally, it is pointed out that the 2MASS fluxes are sometimes in conflict with prior measurements at these wavelengths. Most of these discrepancies are likely to arise from photometric errors, as well as, possibly, from the effects of field-star contamination.
Boundary-Layer Transition Measurements in Hypervelocity Flows in a Shock Tunnel

Experiments to investigate the transition process in hypervelocity boundary layers were performed in the T4 free-piston shock tunnel. An array of thin-film heat-transfer gauges was used to detect the location and extent of the transitional region on a 1500 mm long x 120 turn wide flat plate, which formed one of the walls of a duct. The experiments were performed in a Mach 6 flow of air with 6- and 12-MJ/kg nozzle-supply enthalpies at unit Reynolds numbers ranging from 1.6 x 10(6) to 4.9 x 10(6) m(-1). The results show that the characteristics typical of transition taking place through the initiation, growth, and merger of turbulent spots are evident in the heat-transfer signals. A 2-mm-high excrescence located 440 turn from the leading edge was found to be capable of generating a turbulent wedge within an otherwise laminar boundary layer at a unit Reynolds number of 2.6 x 10(6) m(-1) at the 6-MJ/kg condition. A tripping strip, located 100 mm from the leading edge and consisting of a line 37 teeth of 2 rum height equally spaced and spanning the test surface, was also found to be capable of advancing the transition location at the same condition and at the higher enthalpy condition.
Contribution of obliquely incident particles to neutron monitor counting rate

We describe a new method for calculating geomagnetic cutoffs that incorporates obliquely incident primaries, and we use it to interpret a sea level neutron monitor latitude survey. Effects due to obliquely incident primaries are significant and may be responsible for anomalies observed in this and other latitude surveys. We define an “apparent” cutoff that takes these obliquely incident particles into account. Use of our apparent cutoff in a Dorman function fit to the 1994–1995 Bartol Research Institute-University of Tasmania latitude survey data results in a significant improvement over use of the more conventional effective vertical cutoff.
The NH and CH Bands of Comet C/1996 B2 (Hyakutake)

Abstract Comet Hyakutake was an ideal target for studying the near-nuclear region of a bright comet. On 1996 March 26.3–26.5 (UT) we observed the comet with an echelle spectrometer at the 4-m telescope atop Kitt Peak. High-resolution spectra of NH and CH are presented and compared with fluorescence models. At a spectral resolution of Δλ ≤ 0.2 A two multiplets of ND are not blended by the overlying NH line forest. From these lines we derived a 3σ upper limit for the D/H ratio in NH, (D/H) NH ≤ 0.006. We reevaluated the g -factors for the NH (0–0) band and present g -factors for the strongest ND multiplets as a function of heliocentric velocity. Based on our measurements of the OH and NH (0–0) band we inferred a relative production rate Q (NH 3 )/ Q (H 2 O) = (3.5 ± 1.0) × 10 −3 . We demonstrate that single-cycle fluorescence models can be used to describe the observed CH bands, if we introduce different rotational temperatures for the two spin states, T ( F 1 ) = 100 K and T ( F 2 ) = 130 K. These temperatures are believed to be remnants from a previous dissociative excitation. Obviously collisions or radiative processes cannot completely relax CH before the radical decays. The rotational temperature may thus provide clues to the identity of the CH parent(s). A theoretical analysis of CD suggests that several lines of the CD A – X system are not masked by CH lines.
Real-time interrogation of a linearly chirped fiber Bragg grating sensor based on chirped pulse compression using a Sagnac loop interferometer

A novel approach to interrogating in real time a linearly chirped fiber Bragg grating (LCFBG) sensor based on chirped pulse compression using a Sagnac loop interferometer (SLI) with improved pulse compression performance is proposed and experimentally demonstrated. The proposed system consists of a mode-locked laser (MLL), a SLI incorporating an LCFBG, which makes the SLI have a spectral response with an increasing or decreasing free spectral range (FSR), a dispersive element and a photodetector. The significance of using an SLI incorporating an LCFBG is its capability of providing equal dispersion for two pulses traveling along the clockwise and counter-clockwise paths, which would effectively avoid a non-complete temporal interference, and improves the pulse compression performance. When the fiber sensor is experiencing a strain, the strain information would be conveyed to a wavelength shift caused by the Bragg wavelength change, which is further transferred to the change of the FSR. An ultra-short pulse train generated by the MLL would be spectrum shaped by the SLI, and the shaped spectrum would contain the information of the wavelength change. The demodulation is performed in the time domain by mapping the spectrally shaped waveform to the temporal domain using a dispersion compensating fiber (DCF) as the dispersive element. The generated temporal waveform is then correlated with a special reference waveform, with the location of the correlation peak indicating the wavelength change which reflects the strain or temperature change. A theoretical analysis is carried out, which is validated by an experiment. The experimental results show that the proposed system can provide an interrogation resolution as high as 0.22 με at a speed of 48.6 MHz with a correlation peak to sidelobe ratio of 2.5.
Development of a dichoptic foveal/peripheral head-mounted display with partial binocular overlap

Previous foveal/peripheral display systems have typically combined the foveal and peripheral views optically, in a single eye, in order to provide simultaneously both high resolution and wide field of view from a limited number of pixels. While quite effective, this approach can lead to cumbersome optical designs that are not well suited to head-mounted displays. A simpler approach may be possible in the form of a dichoptic vision system, wherein each eye receives a different field of view (FOV) of the same scene, at different resolutions. One eye would be presented with highresolution narrow-FOV foveal imagery, while the other would receive a much wider peripheral FOV. Binocular overlap in the central region would provide some degree of stereoscopic depth perception. It remains to be determined, however, if such a system would be acceptable to users, or if binocular rivalry or other adverse side-effects would degrade visual task performance compared to conventional head-mounted binocular displays. In this paper, we describe a preliminary dichoptic foveal/peripheral vision system and suggest methods by which its usability and performance can be assessed. This effort was funded by the U.S. Air Force Research Laboratory Human Performance Wing under SBIR Topic AF093-018.
Forces on a slowly rotating, rough cylinder in a Couette device containing a dry, frictional powder

In the present work, a fine, dry powder was sheared in a Couette device: i.e., sheared between concentric vertical cylinders. The torque generated on the rough, inner cylinder was measured as this inner wall was rotated. Our experiments provided evidence that, in a column of granular material undergoing continuous shearing, normal and shear stresses increase linearly with depth. In other words, Janssen’s analysis ceases to apply if granular material is continuously sheared.
Mass transport in a turbulent boundary layer under a progressive water wave

The bottom boundary layer under a progressive water wave is studied using Saffman's turbulence model. Saffman's equations are analysed asymptotically for the case Re [Gt ] 1, where Re is a Reynolds number based on a characteristic magnitude of the orbital velocity and a characteristic orbital displacement. Approximate solutions for the mass-transport velocity at the edge of the boundary layer and for the bottom stress are obtained, and Taylor's formula for the rate of energy dissipation is verified. The theoretical results are found to agree well with observations for sufficiently large Reynolds numbers.
Magnetically induced phase separation and magnetic properties of Co–Mo hexagonal-close-packed structure thin films

Magnetically induced phase separation along the Curie temperature in the hexagonal-close-packed phase of a Co–Mo binary system has been predicted by thermodynamic calculations. Furthermore, the phase separation and magnetic properties of Co–Mo sputtered thin films have been investigated. Nanoscale compositional fluctuation caused by the magnetically induced phase separation has been confirmed in the films deposited on a heated substrate in the same manner as Co–Cr-based alloys. The magnetic anisotropy constant of the Co–Mo films is larger than that of Co–Cr films. From these results, it is concluded that the Co–Mo system is promising for use as a base alloy system for high density recording media.
Comparison of radiation element method and discrete ordinates interpolation method applied to three-dimensional radiative heat transfer

We compare and scrutinize the characteristics of radiation element method by ray emission model (REM 2 ) and discrete ordinates interpolation method (DOIM). A three-dimensional radiative heat transfer problem is solved within a rectangular enclosure containing absorbing, emitting, nonscattering medium with temperatures given as a sine function. The calculation results are validated with the zonal results and the analytical solution
Numerical simulations of tidal tails for the open cluster NGC 188

To aid future observations, we present the results of N-body simulations of tidal tails near the open cluster NGC 188. The simulated tidal tails stretch in both directions along the Galactic orbit of the cluster, extending to distances of at least 1 kpc. The cross-section of a tidal tail does not exceed 40-50 pc. On the sky, the number of tidal stars in the densest parts of a tail can reach a few percent of all visible stars only. The average dispersion of stellar velocities in the tidal tail is 1-3 km s -1 . In velocity space, the tidal tails have a shape of a lengthy 'cold' star flux immersed in the 'hot' Galactic disc background. We provide the predicted position of the tidal tails and the expected distribution of radial velocities along the projection. The expected distribution of tidal star radial velocities has a large range (from -46 to +49 km s -1 ), thus underscoring the importance of predictions in future searches of tidal stars in open clusters. A preliminary search for tidal stars in the Two-Micron All-Sky Survey catalogue was not successful, indicating the need for a new CCD imaging to narrow down the number of possible former members of NGC 188 within the specified range of photometric and kinematic parameters.