Miracle-dz/UniFAR-FTUs huggingface dataset:
Investigations of STGS, SNGS, CTGS, & CNGS materials for use in saw applications

Langasite structure compounds have been the focus of much consideration recently, given their higher electromechanical coupling and similar temperature behavior to that of quartz. Recent investigations have begun on four new materials, STGS, SNGS, CTGS, and CNGS. These langasite structure crystals show great promise for use in SAW applications. In some respects, STGS, SNGS, CTGS, and CNGS exhibit better SAW material properties than the LGX materials (langasite, langanite, and langatate) previously studied. For example, SNGS and STGS have higher electromechanical coupling than LGX, in excess of 0.6% and 0.5%, respectively. In addition, all four materials have lower densities resulting in higher phase velocities. Along with previously studied trigonal 32 class materials, there is a good possibility that temperature compensated cuts exist. Recent results are reported for SAW material parameters and device performance at various propagation directions on Y-cut STGS, SNGS, CTGS, and CNGS wafers. These results include coupling coefficient, phase velocity, transducer capacitance, and temperature coefficient of delay (TCD). Experimental measurements of metal strip reflectivity are shown for various metal thicknesses. Measured SAW resonator Q data are also presented. The measurement procedures and the parameter extraction methods for these experiments are discussed. A comparison of the data with previously reported parameters on LGX is presented and a discussion of the results is provided.
A HIGH-FREQUENCY TYPE II SOLAR RADIO BURST ASSOCIATED WITH THE 2011 FEBRUARY 13 CORONAL MASS EJECTION

We examine the relationship between the high-frequency (425 MHz) type II radio burst and the associated white-light coronal mass ejection (CME) that occurred on 2011 February 13. The radio burst had a drift rate of 2.5 MHz s−1, indicating a relatively high shock speed. From SDO/AIA observations we find that a loop-like erupting front sweeps across high-density coronal loops near the start time of the burst (17:34:17 UT). The deduced distance of shock formation (0.06 Rs) from the flare center and speed of the shock (1100 km s−1) using the measured density from SDO/AIA observations are comparable to the height (0.05 Rs, from the solar surface) and speed (700 km s−1) of the CME leading edge observed by STEREO/EUVI. We conclude that the type II burst originates even in the low corona (<59 Mm or 0.08 Rs, above the solar surface) due to the fast CME shock passing through high-density loops.
Quasi-static rheology of foams. Part 2. Continuous shear flow

The evolution of a bidimensional foam submitted to continuous quasi-static shearing isinvestigated both experimentally and numerically. We extract, from the images of the sheared foam, the plastic flow profiles as well as the local statistical properties of the stress field. When the imposed strain becomes larger than the yield strain, the plastic events develop large spatial and temporal correlations, and the plastic flow becomes confined to a narrow shear band. This transition and the steady-state regime of flow are investigated by first focusing on the elastic deformation produced by an elementary plastic event. This allows us to understand (i) the appearance of long-lived spatial heterogeneities of the stress field, which we believe are at the origin of the shear-banding transition, and (ii) the statistics of the dynamic fluctuations of the stress field induced by plastic rearrangements in the steady-state regime. Movies are available with the online versionof the paper.
Properties of higher order stochastic cycles

Abstract. This article investigates a general class of stochastic cycles, presenting the main properties in the time and frequency domains. Harvey and Trimbur [Review of Economics and statistics (2003) Vol. 85, pp. 244–55] showed how generalized cyclical processes may be used in unobserved components models to extract smoother cycles in economic series. The stochastic cycle models allow for a flexible description of periodic behaviour in time series data. In the frequency domain, a wide variety of peaked spectral shapes, characteristic of time‐varying cyclical dynamics, is produced. The parameters have a direct interpretation, so cyclical behaviour may be studied directly; in a Bayesian approach, the researcher may implement prior views on the period in a consistent way. Extensions to multivariate models are possible.
NONLINEAR VIBRATIONS OF RECTANGULAR LAMINATED COMPOSITE PLATES WITH DIFFERENT BOUNDARY CONDITIONS

Nonlinear vibrations of rectangular laminated composite plates with different boundary conditions are studied by using different nonlinear plate theories. In particular, numerical results for (i) the classical Von Karman theory, (ii) the first-order shear deformation theory (SDT), and (iii) the third-order SDT are compared. The nonlinear response to harmonic excitation in the frequency neighborhood of the fundamental mode is investigated. Numerical investigation is carried out by using pseudo-arclength continuation method and bifurcation analysis. The boundary conditions of the plates are: simply supported with movable edges, simply supported with immovable edges, and clamped (CL) edges. For thick plates (thickness ratio 0.1), the strongest hardening nonlinear behavior is observed for CL plates, while the simply supported movable plates are the ones with the weakest nonlinearity among the three different boundary conditions studied here. Differences among the three nonlinear plate theories are large for thick laminated plates. For all the other cases, the first-order SDT, with shear correction factor , and the higher-order SDT give almost coincident results.
Panel Damping Loss Factor Estimation Using the Random Decrement Technique

ANEL damping loss factors can be computed using a number of techniques based on measured responses and, depending on the algorithm chosen, based on measured excitation forces as well. These many techniques are based on a range of mathematical models, including both continuous and discretized formulations. Here, a single degree of freedom model and a linear finite element-based model of a free, uniform thin plate are used to simulate the measurements needed for the Random Decrement Technique (RDT). In particular, the computational models are given a range of structural damping levels; then, the estimation techniques are used to “recover” the given level of damping. Presumably, if the validation is positive, the technique will be considered a valid process for measurements on actual structures. Comparisons with the Impulse Response Decay Method (IRDM) have been conducted using three damped plates. P
Asymptotic similarity of turbulence structures in smooth- and rough-walled pipes

Work recently reported by the authors (Perry & Abell 1975) on smooth-walled pipe flow showed support for the Townsend (1976) structural similarity principle as regards viscosity not being directly relevant in controlling the mean relative motions and the energy-containing turbulent motions. The work also supported a universal spectral behaviour in the wall region of the flow. In many hypotheses for rough-walled pipe flow, surface roughness, like viscosity, enters the problem only via external boundary conditions. Data obtained in a rough pipe are reported here and on first appearance the results seem to contradict the Townsend hypothesis and to threaten the very foundation upon which many similarity laws for rough-walled flows are based. However, on closer examination of the spectrum scaling of smooth-walled pipe flow the low and high wavenumber energy not necessarily associated with the universal similarity range can be accounted for. The broad-band longitudinal turbulence results for a rough-walled pipe can then be predicted from the smooth-wall scaling. The conclusion is that, despite the apparent anomalies, the turbulence structure in a rough pipe appears to follow the same scaling laws as for a smooth pipe, given a sufficient length of flow development in both cases. The deduced functional forms are consistent with Townsend's (1976) attached-eddy hypothesis.
On the accuracy of high-order Yule-Walker methods for cisoids

The asymptotic properties of the high-order Yule-Walker (HOYW) estimators of the frequencies of complex sine waves are investigated. An explicit formula is derived for the covariance matrix of the corresponding estimation errors. An analytical study of the HOYW error covariance matrix shows that its elements are inversely proportional to the squared signal-to-noise ratio, enjoy a certain invariance to frequency shifts, and decrease significantly as the number of YW equations and the model order increases. These properties are also shared by the MUSIC and ESPRIT methods. A numerical study of the performance of these three methods shows that the HOYW method usually gives the best tradeoff between statistical accuracy and computational complexity. <<ETX>>
One-Year Operational Measurements with a Sonic Anemometer-Thermometer and a Doppler Sodar

Abstract A Doppler sodar and an ultrasonic anemometer–thermometer, which are operated continuously at a nuclear research center in Germany, are described. Mean values and second moments including turbulent surface fluxes recorded over 1 yr are analyzed in order to assess their credibility. Particularly, the effects of rain on the data quality and the statistical bias caused by a reduced data availability—typical for remote sensing measurements—are investigated. Mean profiles of the vertical wind variance for different classes of Monin–Obukhov length, the mean vertical wind component versus wind direction, and the annual variation of 24-h averages of the surface heat flux are presented.
VLA Observations of the Inner Lobes of Centaurus A

Scaled-array VLA observations of the closest active radio galaxy Centaurus A at 1.4, 1.6, and 4.9 GHz with 4.5 ″ × 1.2″ resolution have been used to derive the spectral and polarimetric properties of the inner radio lobes of the source. The extended emission of the lobes is filamentary, similar to other well-resolved radio galaxies. Two compact radio features have been detected in the southern lobe which are roughly aligned with the axis of the main jet. This may be the first indication of a counterjet in Centaurus A
Evidence for a triaxial bulge in the spiral galaxy NGC 4845

Spectroscopic observations for the Sa galaxy NGC 4845 in five position angles reveal a regular but nonaxisymmetric velocity field for the gas at r of 1.5 kpc or less. Photometry indicates a possible slight twisting between the disk and bulge isophotes. These phenomena are interpreted as a manifestation of a triaxial bulge, and estimates of the ranges of b/a and c/a are obtained. 20 refs.
International surveys of educational achievement: how robust are the findings?

Summary. International surveys of educational achievement and functional literacy are increasingly common. We consider two aspects of the robustness of their results. First, we compare results from four surveys: the Trends in International Maths and Science Study, the Programme for International Student Assessment, the Progress in International Reading Literacy Study and the International Adult Literacy Survey. This contrasts with the standard approach which is to analyse just one survey in isolation. Second, we investigate whether results are sensitive to the choice of item response model that is used by survey organizers to aggregate respondents’ answers into a single score. In both cases we focus on countries’ average scores, the within‐country differences in scores and on the association between the two.
Analytical and numerical solution to the two-potential Zakharov-Shabat inverse scattering problem

An analytical and a numerical method are presented in order to solve the inverse scattering problem associated with the two-potential Zakharov-Shabat coupled mode equations. The numerical solution, which uses leapfrogging in space and time, represents a direct numerical solution to the coupled Gel'fand-Levitan-Marchenko (GLM) integral equations as an extension of the authors' previous work on GLM equations of simpler form. The analytical method, which is applied for one-pole reflection coefficients, consists in constructing appropriate differential operators which transform the coupled GLM equations to ordinary linear differential equations. An application of these methods for nonuniform transmission line synthesis is presented. >
Mentoring preservice teachers in primary mathematics

A literature-based instrument gathered data about 147 final-year preservice teachers‟ perceptions of their mentors‟ practices related to primary mathematics teaching. Five factors characterized effective mentoring practices in primary mathematics teaching had acceptable Cronbach alphas, that is, Personal Attributes (mean scale score=3.97, SD [standard deviation]=0.81), System Requirements (mean scale score=2.98, SD=0.96), Pedagogical Knowledge (mean scale score=3.61, SD=0.89), Modelling (mean scale score=4.03, SD=0.73), and Feedback (mean scale score=3.80, SD=0.86) were . 91, . 74, . 94, . 89, and . 86 respectively. Qualitative data (n=44) investigated mentors‟ perceptions of mentoring these preservice teachers, including identification of successful mentoring practices and ways to enhance practices.
Emission Measure Distribution for an Active Region Using Coordinated SERTS and Yohkoh SXT Observations

Often the derived temperature of an active region reflects the method and the nature of the instrument used in its measurement. The emission measure (i.e., the amount of emitting material) derived from spectroscopic observations usually depends on assumptions about the absolute elemental abundances and ionization fractions of the emitting ions. Yet establishing the distribution of emission measure with temperature is the first step needed to proceed with most of the interesting physics of active regions—including heating processes, cooling timescales, and loop stability. Accurately characterizing the thermal distribution of the coronal plasma requires data which can resolve multithermal features and constrain both low- and high-temperature emission. To model the temperature distribution of NOAA Active Region 7563, we have combined broadband filter data from the Yohkoh Soft X-Ray Telescope (SXT) with simultaneous spectral line data from the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) taken during its flight on 1993 August 17. We have used a forward-folding technique to determine the emission measure distribution of the active region loops. We have found that (1) the SXT response functions are sensitive to both the elemental abundances and the ionization fractions assumed to compute the solar spectrum that is folded through the instrument effective area; (2) the relative calibration between the SERTS and the SXT instruments must be adjusted by a factor of 2 (a value consistent with the absolute measurement uncertainty of the 1993 SERTS flight) no matter which abundances or iron ionization fractions are used; (3) the two-peaked differential emission measure previously determined using SERTS data alone is not consistent with the SXT data: including the SXT data as a high-temperature constraint in the analysis requires that the emission above about 3 MK drop off steeply rather than extending out to 6 MK. The sensitivity of the SXT filter response functions to elemental abundance and iron ionization fraction could have a major impact on many routine analyses of SXT data. The emission measures can be greatly affected (up to a factor of 7) and temperatures derived from filter ratios can be significantly altered (up to at least 40%) by adopting different sets of commonly used elemental and ionic abundances. The results of our multithermal analysis imply that using broadband SXT data or a comparable high-temperature constraint in conjunction with high-resolution spectra covering a wide lower temperature range to study solar active regions can significantly improve the information derived from either data set alone. In this study, the revised multithermal distribution reduces the thermal energy content of the region by about a factor of 2 and the required heating by about a factor of 5, which in turn relaxes some constraints on possible heating models.
Note on N‐dimensional hermite polynomials

I t is well known that a complete set of orthonormal polynomials in N variables can be obtained by using products of such polynomials in a single variahle. Such a procedure lacks symmetry, and there is sometimes an advantage to be gained by expressing the polynomials in tensor invariant notation. The -\--vector z,(i = 1, 2, . . . , X ) is denoted by x. The second order tensor (dyad) X , X , is denoted by x'. Similarly, xn is used for the n-th order tensor x,,xi2 x,, . For the scalar product I t is convenient to introduce a special notation.
High-Frequency Permeance Measurements Using a Microstrip Coil

We developed a new thin-film permeance meter that is effective from 10 MHz to 1.5 GHz, using a microstrip pickup coil that senses the change in flux in a film sample driven in the TEM propagation mode. The microstrip pickup coil allows broader-band measurement of the permeance than a figure-8-coil, because impedance matching is provided. The influences of the exciting electric fields and the higher-order mode in the driving coil on the permeance measurement are analyzed. A strong de field (170 Oe) is applied parallel to the easy axis during the reference voltage measurement in order to eliminate the influence of the electric field.
Near-Infrared Camera and Multi-Object Spectrometer Observations of the Hubble Deep Field: Observations, Data Reduction, and Galaxy Photometry

This paper presents data obtained during the NICMOS Guaranteed Time Observations of a portion of the Hubble Deep Field. The data are in a catalog format similar to the publication of the original WFPC2 Hubble Deep Field program (Williams et al.). The catalog contains 342 objects in a 49. ″1 × 48. ″4 subfield of the total observed field, 235 of which are considered coincident with objects in the WFPC2 catalog. The 3 σ signal-to-noise ratio level is at an aperture AB magnitude of approximately 28.8 at 1.6 μm. The catalog sources, listed in order of right ascension, are selected to satisfy a limiting signal-to-noise ratio criterion of greater than or equal to 2.5. This introduces a few false detections into the catalog, and users should take careful note of the completeness and reliability levels for the catalog discussed in §§ 9 and 10. The catalog also contains a test parameter indicating the results of half-catalog tests and the degree of coincidence with the original WFPC2 catalog.
Law of the wall for turbulent flows in pressure gradients

Experiments show that pressure gradients have a strong effect on the law of the wall for temperature but have comparatively little effect on the law of the wall for velocity. This is contrary to the predictions of the mixing-length formulas, though these can be derived by apparently plausible dimensional analysis. To model this behavior, the choice of the transport equation for the turbulence-length scale, or its equivalent, becomes crucial; this is true both for two-equation models and for full second-moment transport models. This paper is a brief review of the experimental evidence, followed by a demonstration that the most popular "length-scale" variable, the dissipation rate e, and its temperature-field equivalent ej fail to reproduce the observed behavior. A more general length-scale variable can be defined as ^"e", where k is the turbulent kinetic energy. It is shown that, overall, the u; variable (m = — 1, n = 1) seems to be the best choice, with its temperature-field equivalent UT for heat transfer, although there is no obvious physical reason for preferring it. Nomenclature A+ =
Lifetime for the 2 3Po2 level in 58Ni26+ using beam-two-foil experiments

The lifetime of the 2 3Po2 level in He-like 58Ni has been measured using the beam-foil time of flight technique with single- as well as two-foil targets at various beam energies. This technique disentangles contributions arising from the H-like M1 and the Li-like M2 lines and yields a lifetime for the 2 3Po2 level in He-like 58Ni (70 ± 3 ps) in good agreement with previous theoretical (70.6 ps) and experimental (70 ± 3 ps) values.
A model of anisotropic grain-oriented steel

In this work the magnetic flux distribution in the grain-oriented steel core transformer is investigated with the finite element method. A mathematical model (Model II) is obtained for the reluctivity tensor. The model, optimized by means of experimental values of the B-H curve, predicts different directions of the magnetization field, not just along the rolling and transverse directions of the material. The results are the flux maps, as well as the reactance values and the electrodynamic forces on the windings. These results, obtained by means of the isotropic model and the anisotropic first model [1], are compared with the experimental ones.
Nonlinear analysis of buoyant convection in binary solidification with application to channel formation

We consider the problem of nonlinear thermal-solutal convection in the mushy zone accompanying unstable directional solidification of binary systems. Attention is focused on possible nonlinear mechanisms of chimney formation leading to the occurrence of freckles in solid castings, and in particular the coupling between the convection and the resulting porosity of the mush. We make analytical progress by considering the case of small growth Péclet number, δ, small departures from the eutectic point, and infinite Lewis number. Our linear stability results indicate a small O(δ) shift in the critical Darcy-Rayleigh number, in accord with previous analyses. We find that nonlinear two-dimensional rolls may be either sub- or supercritical, depending upon a single parameter combining the magnitude of the dependence of mush permeability on solids fraction and the variations in solids fraction owing to melting or freezing. A critical value of this combined parameter is given for the transition from supercritical to subcritical rolls. Three-dimensional hexagons are found to be transcritical, with branches corresponding to upflow and lower porosity in either the centres or boundaries of the cells. These general results are discussed in relation to experimental observations and are found to be in general qualitative agreement with them.
A unified approach for mean square stability of continuous-time Markovian jumping linear systems with additive disturbances

Necessary and sufficient conditions for mean square stability (MSS) of continuous-time linear systems subject to Markovian jumps in the parameters and additive disturbances are established. We consider two scenarios regarding the additive disturbances: one in which the system is driven by a Wiener process, and one characterized by functions in L/sub 2//sup m/(R/sup +/), which is the usual scenario for the H/sub /spl infin// approach. For both cases it is shown that MSS is equivalent to asymptotic wide sense stationarity (AWSS), to the spectrum of an augmented matrix lying in the open left half plane, and to the existence of a solution for a certain Lyapunov equation. Furthermore, it is proved that the Lyapunov equation can be written down in two equivalent forms with each one providing an easier-to-check sufficient condition. It is also shown that MSS is equivalent to the state x(t) belonging to L/sub 2//sup m/ whenever the disturbances are in L/sub 2//sup m/-(R/sup +/). These results provide, inter alia, a flexible theory, in a unified basis, for MSS of continuous-time Markovian jump linear systems.