Miracle-dz/UniFAR-FTUs huggingface dataset:
Vortex shedding from a square cylinder near a wall

Wake velocity and cylinder pressure measurements are used to investigate the changes in the vortex shedding from a square cylinder near a solid wall at a Reynolds number of 19 000. The phase-averaged velocity field shows that vortex formation is displaced downstream due to the presence of the wall. Reattachment of the shear layer on the lower cylinder face interrupts the coupling of the upper and lower shear layers so that suppression of vortex shedding occurs for a gap height to diameter ratio, S/D < 0.4. Circulation ratios at suppression are consistent with the extension of von Karman's stability analysis for two rows of alternating vortices of unequal strength. It is observed that vortex shedding becomes increasingly intermittent for gap height ratios below 0.5 as a result of the straightening of the separated shear layers and reduced coupling between them. This article was chosen from selected Proceedings of the Second International Symposium on Turbulence and Shear Flow Phenomena (KTH-Stockholm, 27-2.
A Rotated Principal Component Analysis of the Interannual Variability of the Northern Hemisphere 500 mb Height Field

Abstract The principal components derived by Wallace and Gutzler (1981) from a 500 mb height data set are linearly transformed using the varimax method. Their data set consists of 45 winter months of National Meteorological Center analyses of Northern Hemisphere 500 mb height. The linear transformation (or rotation) of the principal components emphasizes the strongest relationships within the 500 mb height data set; hence, spatial patterns associated with the rotated principal components are simpler to interpret than the spatial patterns associated with the unrotated components. The teleconnection patterns identified by Wallace and Gutzler (1981) on the basis of the negative extrema approach closely resemble several of the spatial patterns of the rotated principal components. In order to show the seasonal dependence of the rotated principal components, an expanded data set consisting of 30 years of 500 mb height data is used. Most of the teleconnection patterns derived from the 90 winter month data set ar.
Variability of EUV-spectra from the quiet upper solar atmosphere: Intensity and Doppler shift

We have studied SUMER and CDS time series of spectra and images of quiet-Sun regions at the solar disc centre. The data contain ultraviolet emission lines sampling temperatures of the chromosphere, transition region and corona. We find a high correlation between average net Doppler shifts and relative brightness variabilities of the studied lines (correlation coecient of 0:92), suggesting a connection between the two quantities. The anti-correlation between dierential emission measures and relative brightness variabilities is weaker (correlation coecient of 0:78). We discuss the observed relationships on the basis of dierential emission measures and linear wave calculations.
Examining the Types of Problem Solving Strategies Used by Children with Intellectual Disabilities During Modified Schema Based Instruction

he current study examined the problem solving strategies used by children with intellectual disabilities (ID group) before and after a modified Schema Based Instruction (MSBI) intervention, and compared the strategies to those of children who were (a) struggling with mathematics (SM group) and (b) of average mathematics ability (AM group). The potential impact of MSBI on children’s ability to use appropriate strategies, to use more than one strategy to solve a given problem, and to identify the problem structure was also assessed. All three groups received three hours of MSBI on how to solve a specific type of addition and subtraction word problems. Results demonstrated marked differences in strategy types across groups, with children in the ID group favoring strategies unrelated to the mathematical action or context, and children in the AM and SM groups using standard algorithms during the pretest. Following the MSBI intervention, children in the ID group began to use Direct Modeling strategies. In both the SM and AM groups, most students continued to use the standard algorithm. In the SM group, however, there was more variability with some students using some Direct Modeling strategies. All children showed improvement on appropriateness of strategies and identification of word problem structure following instruction, with the biggest gains observed for children in the ID and SM groups, respectively. The results of this study show promise for the use of MSBI in inclusive classrooms to help students with different abilities learn to successfully solve word problems.
Analysis of Thermal Effects in Cavitating Liquid Hydrogen Inducers

Evaporative cooling effects due to cavitation can significantly improve the performance of liquid rocket turbomachinery that operate with cryogenic fluids, in which the fluid is operating close to its critical temperature and the thermal effects resulting from phase change become important. A detailed numerical analysis to quantify these thermal effects of cavitation and to better understand their impact on cavitation flow physics in liquid hydrogen inducers is presented. Simulations were performed on a helical flat-plate inducer that was extensively tested in both liquid hydrogen and cold water. Predictions of cavitating performance over the operational range of inlet pressures were conducted and compared with experimental data. Fundamental differences were observed in the cavity for liquid hydrogen compared with the cold-water inducer; the cavity in liquid hydrogen shows far less vapor content, although spreading out further in the spanwise direction, which may generate blade-to-blade interactions. Thermal effects result in a more gradual breakdown of the head in liquid hydrogen resulting in improved overall performance; the liquid hydrogen inducer performed to a suction specific speed (N SS number) of 75,000 and the corresponding value in water is 35,000. The temperature depressions due to evaporative cooling in the liquid hydrogen fluid are found to be only on the order of 0.5-1.0 K, highlighting the strong coupling of thermodynamic properties and the phase-change process at these flow conditions.
Feeling Smart: The Science of Emotional Intelligence

O the past decade almost everyone tuned in to American popular culture has heard the term emotional ink'ltigena'. As a new concept, emotional intelligence has been a hit: It has been the subject of several books, including a best seller, and myriad talk-show discussions and seminars for schools and organizations. Today you can hire a coach to help you raise your "EQ," your emotional quotient—or your child's. Despite (or perhaps because of) its high public profile, emotional intelligence has attracted considerable scientific criticism. Some of the controversy arises from the fact that popular and scientific definitions of emotional intelligence differ sharply. In addition, measuring emotional intelligence has not been easy. Despite these difficulties, research on emotional intelligence has managed to sustain itself and in fact shows considerable promise as a serious iine of scientific inquiry. It turns out that emotional intelligence can indeed be measured, as a set of
Interaction of a vortex ring with a piston vortex

Recent studies on vortex ring generation, e.g. Rosenfeld et al. (1998), have highlighted the subtle effect of generation geometry on the final properties of rings. Experimental generation of vortex rings often involves moving a piston through a tube, resulting in a vortex ring being generated at the tube exit. A generation geometry that has been cited as a standard consists of the tube exit mounted flush with a wall, with the piston stroke ending at the tube exit, Glezer (1988). We employ this geometry to investigate the effect of the vortex that forms in front of the advancing piston (piston vortex) on the primary vortex ring that is formed at the tube exit. It is shown that when the piston finishes its stroke flush with the wall, and hence forms an uninterrupted plane, the piston vortex is convected through the primary ring and then ingested into the primary vortex. The ingestion of the piston vortex results in an increased ring impulse and an altered trajectory, when compared to the case when the piston motion finishes inside the tube. As the Reynolds number of the experiments, based on the piston speed and piston diameter, is the order of 3000, transition to turbulence is observed during the self-induced translation phase of the ring motion. Compared to the case when the piston is stopped inside the tube, the vortex ring which has ingested the piston vortex transitions to turbulence at a significantly reduced distance from the orifice exit and suggests the transition map suggested by Glezer (1988) is under question. A secondary instability characterized by vorticity filaments with components in the axial and radial directions, is observed forming on the piston vortex. The structure of the instability appears to be similar to the streamwise vortex filaments that form in the braid regions of shear layers. This instability is subsequently ingested into the primary ring during the translation phase and may act to accelerate the growth of the Tsai–Widnall instability. It is suggested that the origin of the instability is Görtler in nature and the result of the unsteady wall jet nature of the boundary layer separating on the piston face.
Assessing Equating Results on Different Equating Criteria

The performance of three equating methods— the presmoothed equipercentile method, the item response theory (IRT) true score method, and the IRT observed score method—were examined based on three equating criteria: the same distributions property, the first-order equity property, and the second-order equity property. The magnitude of the difficulty differences in the alternate forms was found to affect the extent to which the three equating properties hold. The Iowa Tests of Basic Skills (ITBS) standardization data and simulated data were analyzed in the study. The results showed that when the raw score distributions of alternate forms are similar, all three methods lead to adequate equating regardless of the criterion used. When the raw score distributions are dissimilar, to preserve the first order equity property, the IRT true score method performs best; to preserve the same distributions and second order equity properties, the equipercentile method and the IRT observed score method both perform well. The greater the difficulty difference between alternate forms, the less likely the first and second order equity properties hold. These results are intended to inform equating practice by suggesting, for actual equatings, the size of form-to-form differences that can lead each equating method to perform well and poorly relative to the various criteria.
Effect of Degenerate Semiconductor Band Structure on Current-Voltage Characteristics of Silicon Tunnel Diodes

The three components of the band-to-band tunnel current of silicon Esaki junctions at low temperatures, the phonon-unassisted current ${i}_{0}$, the TA phonon-assisted current ${i}_{1}$, and the TO phonon-assisted component ${i}_{2}$, have been derived from the experimental current-voltage characteristics by an empirical, but extremely self-consistent, technique. The components are in constant ratio to each other for a given donor species but junctions formed using Sb gave relatively lower ${i}_{0}$ currents than did junctions formed with P- or As-doped material. The three current components have very similar bias dependence which, empirically, turns out to be accurately described by $V\mathrm{exp}(\ensuremath{-}{\ensuremath{\beta}}^{\ensuremath{'}}V)$, where ${\ensuremath{\beta}}^{\ensuremath{'}}$ is a constant for a given junction. Part of the exponential factor represents the bias dependence of the tunneling probability, the remainder enters into the "effective density of states" function. The true peak voltage is given by $\frac{1}{{\ensuremath{\beta}}^{\ensuremath{'}}}$. The experimental current-voltage curves are compared with each of Kane's theories; the first is for undistorted band edges while the second takes account of the band edge tails in very impure semiconductors. Good agreement is obtained using the latter theory, both as to the over-all shape of the curves and the actual values of the peak voltages.
Numerical Simulations of the Genesis of Typhoon Nuri (2008): Sensitivity to Initial Conditions and Implications for the Roles of Intense Convection and Moisture Conditions

AbstractThe sensitivity of numerical simulations of the genesis of Typhoon Nuri (2008) to initial conditions is examined using the Advanced Research core of the Weather Research and Forecasting (WRF) Model. The initial and boundary conditions are derived from two different global analyses at different lead times. One simulation successfully captures the processes of Nuri’s genesis and early intensification, whereas other simulations fail to predict the genesis of Nuri. Discrepancies between simulations with and without Nuri’s development are diagnosed. Significant differences are found in the development and organization of the intense convection during Nuri’s pregenesis phase. In the developing case, convection evolves and organizes into a “pouch” center of a westward-propagating wavelike disturbance. In the nondeveloping case, the convection fails to develop and organize. Favorable conditions for the development of deep convection include strong closed circulation patterns with high humidity, especially.
Measurement of the geometric and kinematic properties of microscale breaking waves from infrared imagery using a PIV algorithm

Infrared techniques have been shown to be uniquely capable of detecting and quantifying microscale breaking waves at an air–water interface. Here we extend current capabilities by developing image processing algorithms to measure the crest lengths and velocities of microbreaking waves in a laboratory wind–wave tank. The measurements are used to compute the distribution of crest lengths as a function of speed, Λ(c), introduced by Phillips [1] as a formulation for the distribution of breaking waves. Two methods to determine the crest velocity by applying a particle imaging velocimetry (PIV) algorithm to the infrared imagery are developed and compared to a method based on tracking the centroid of the crest. The crest-PIV method is based on estimation of the velocity of crests identified using a temperature threshold. The image-PIV method is based on a velocity threshold applied to a surface velocity map obtained by using the PIV algorithm over the entire image. Both methods are used to compute the surface turnover rate, which is compared to the frequency of breaking. The methods developed demonstrate the potential for infrared imaging techniques to measure the geometric and kinematic properties of microbreaking waves and are relevant to air–sea flux studies.
Nonlinear theory of elastic surfaces.

The present paper develops a nonlinear theory for the deformation of an elastic surface by assuming the existence of a strain energy function and postulating a principle of virtual work which governs its mechanical behavior. By considering the strain energy function to depend on the first‐ and second‐order deformation gradients, the field equations and the general constitutive relations are obtained. In addition to the conventional couple stresses, there are shown to exist energetically undetermined double stresses without moment.
A Robust Algorithm in Sequentially Selecting Subset Time Series Systems Using Neural Networks

In this paper a numerically robust lattice‐ladder learning algorithm is presented that sequentially selects the best specification of a subset time series system using neural networks. We have been able to extend the relevance of multilayered neural networks and so more effectively model a greater array of time series situations. We have recognized that many connections between nodes in layers are unnecessary and can be deleted. So we have introduced inhibitor arcs, reflecting inhibitive synapses. We also allow for connections between nodes in layers which have variable strengths at different points of time by introducing additionally excitatory arcs, reflecting excitatory synapses. The resolving of both time and order updating leads to optimal synaptic weight updating and allows for optimal dynamic node creation/deletion within the extended neural network. The paper presents two applications that demonstrate the usefulness of the process.
THICK RECTANGULAR PLATES ON AN ELASTIC FOUNDATION

The refined theory for moderately thick plates presented in references is used for the bending of plates on elastic foundations. This theory incorporates the transverse normal strain effect in addition to the transverse shear and normal stress effects. Investigation of various types of fixity of edges involving three boundary conditions is presented. The solution of the governing equations using the Navier and Levy type semi-inverse methods is demonstrated. Results are tabulated for the deflection at the center of a uniformly loaded, simply-supported rectangular plate. Applications of the theory also include an infinite plate with a line load of intensity P. Comparisons are made with the classical plate theory and the corresponding Reissner plate theory. The results show the increasing influence of the transverse normal strain on the plate behavior as the parameters characterizing the influence of the plate thickness, h/a, and the modulus k are increased.
Relativistic spin-dependent Compton scattering from electrons

The differential cross section for photon scattering from relativistic polarized free electrons in motion is derived. The calculation extends early results from electrons at rest. It is argued that the present derivation is required for use in bound-state spin-dependent Compton scattering from polarized electrons. The results provide an alternative check on recent work carried out using a quasi- p relativistic Hamiltonian.
Alternative to the Shuttleworth formulation of solid surface stress

We examine two derivations of the Shuttleworth equation (which is a relation between surface stress $g,$ surface tension \ensuremath{\gamma}, and surface strain), and identify the flaws we perceive. Rectifying the perceived flaws leads not to the Shuttleworth equation but to $g\ensuremath{-}\ensuremath{\gamma}$ equivalence. We conclude that surface stress is merely the generalization of the concept of surface tension to an elastically anisotropic system; the surface free-energy density is one-half of the trace of the surface stress tensor, to lowest order. In our opinion, our conclusions lead to a more coherent and elegant form of surface thermodynamics which should prove useful in controlling and in understanding nanometer-scale fabrication.
Highly efficient and stable sky blue organic light-emitting devices

A highly efficient and stable sky blue organic light-emitting device doped with a sky blue dopant BUBD-1 has been fabricated, achieving an electroluminescence efficiency of 13.2cd∕A and 6.1lm∕W at 20mA∕cm2 and 6.7V, with Commission Internationale del’Eclairage coordinates of (0.16, 0.30) and a half-decay lifetime of 1815h at an initial brightness of 2640cd∕m2. This performance is one of the best blue devices ever reported without using hole blocking layer or any p or n dopant in hole or electron transport layer.
Damped Lyα Gas Metallicities at Redshifts z = 0.9-2.0 from Sloan Digital Sky Survey Spectra

Using Sloan Digital Sky Survey early data release spectra, we have identified 370 Mg II absorption systems with Mg II λ2796 rest equivalent widths ≥1 Å and redshifts z = 0.9-2.2. From our previous and ongoing Hubble Space Telescope UV spectroscopic studies, we estimate that the mean neutral hydrogen column density of a system selected in this manner is N = × 1020 atoms cm-2, which corresponds to the damped Lyα (DLA) regime. We have formed high signal-to-noise ratio composite spectra using 223 of these systems with z = 0.9-2.0 in order to study the strength of the Zn II and Cr II absorption lines corresponding to this mean neutral hydrogen column density. After making a correction for missed DLAs, overall we find that [Zn/H] = -1.13 ± 0.19. We find [Cr/Zn] = -0.45 ± 0.13, which indicates that ≈65% of the Cr is depleted onto grains, but this does not correct for the missed DLAs. We have also derived Zn and Cr abundances in two kinematic regimes, and within each regime we consider two redshift intervals. We find trends that indicate that metallicities are higher in the composites in which the absorption has larger velocity spreads as measured by Mg II λ2796 rest equivalent width. Larger velocity spreads may correspond to deeper gravitational potential wells that represent more massive and chemically evolved structures and/or regions associated with winds from starbursting galaxies, also leading to kinematically broad structures of chemically enriched gas. Within the large velocity spread regime, we find that at lower redshifts the Zn metallicity is larger and more Cr is depleted onto grains.
COMMENTS ON 'REVERSE AUCTION: THE LOWEST UNIQUE POSITIVE INTEGER GAME'

In Zeng et al. [Fluct. Noise Lett. 7 (2007) L439–L447] the analysis of the lowest unique positive integer game is simplified by some reasonable assumptions that make the problem tractable for arbitrary numbers of players. However, here we show that the solution obtained for rational players is not a Nash equilibrium and that a rational utility maximizer with full computational capability would arrive at a solution with a superior expected payoff. An exact solution is presented for the three- and four-player cases and an approximate solution for an arbitrary number of players.
Polarimetric studies of comet Levy 1990 XX

The spherical and non-spherical dust-grain characteristics of comet Levy 1990 XX are studied in this paper. Using T-matrix theory, a good theoretical fit to the polarisation data observed by Chernova and co-workers for comet Levy 1990 XX is reported in the present work. The calculated degree of linear polarisation ( p ) as a function of observed scattering angle $(\theta)$ produced by prolate spheroidal crystalline olivine particles with effective radius ($r_{\rm eff}=0.218~ \mu$m), effective variance ($v_{\rm eff}= 0.0036$), and aspect ratio ($E=0.486$) are compatible with the comet's observed polarisation at $\lambda= 0.485~ \mu$m. After comparing the above result with the Mie theory result ($r_{\rm eff}=0.115~ \mu$m, $v_{\rm eff}= 0.0465$), it is found that prolate grains give the better fit to the observed polarisation data. Also, the negative polarisation behaviour of comet Levy 1990 XX is discussed.
Observation of magnetic switching in submicron magnetic-tunnel junctions at low frequency

Understanding the magnetic switching behavior in micron and submicron scale specimens is important for a number of applications. In this study, magnetic-tunnel junctions of various sizes and shapes were fabricated and their switching behavior was studied in detail. Using exchange bias to offset the magnetic response of one electrode, the response of the other (free) electrode was determined from measurements of junction resistance. Switching threshold curves were measured by sweeping magnetic fields in both easy and hard direction. Single domain like switching was observed in some of our smallest submicron junctions. The observed behavior was compared with predictions from the Stoner–Wohlfarth rotational model and from numerical calculations.