Miracle-dz/UniFAR-FTUs huggingface dataset:
Frictional Resistance of Enclosed Rotating Cones With Superposed Throughflow

The research summarized in this paper is an experimental study of the frictional moment on a cone rotating in a conical casing with an outward throughflow. The cone vertex angles tested in the present experiment are θ = 30, 60 and 90 deg. In the region where the frictional moment on the rotating cone with no throughflow is increased by the effect of Taylor-type vortices, an increase of the throughflow rate results in a decrease of the frictional moment, if the throughflow rate is not so large. In the region where the Taylor-type vortices have no appreciable effect on the frictional moment, on the other hand, the rate of increase in CM with increasing Cq. sin (θ/2) is almost independent of θ, where CM and Cq denote the moment coefficient and the dimensionless throughflow rate, respectively.
Testing the Equality of Two Independent Binomial Proportions

Abstract The problem of testing equality of two independent binomial proportions is reexamined. A recent article by D'Agostino, Chase, and Belanger (1988) argues that the Fisher exact test and the Yates chi-squared test with continuity correction are much too conservative in small samples. The authors proposed using a studentized version of the Pearson chi-squared test, and showed that the empirical size of this test is generally close to the nominal level in repeated product-binomial sampling. Although the article is persuasive on its own terms, two central issues are completely ignored: (a) the propriety of analyzing tests based on discrete data using fixed nominal levels of significance, and (b) the question of whether the empirical size should be computed in repeated samples that fix one or both of the margins. The latter is the key issue; Yates and others (1984) argued that both margins should be held fixed for inference, even though only one margin is fixed by the product-binomial sampling design. T.
Measuring Attitudes With a Threshold Model Drawing on a Traditional Scaling Concept

This paper presents a generalized Rasch model for measuring attitudes which is based on the concepts of Thurstone's method of successive intervals. The model combines the rating scale and the dispersion model proposed by Andrich and a submodel of the partial credit model proposed by Masters. An estimation pro cedure for unconditional maximum likelihood (ML) es timates is outlined. A recursion formula for the sym metric functions, which is needed for conditional ML procedures, is given. The benefits of the model are il lustrated with a study on students' interest in physics. The fit of different threshold models can be compared using conditional likelihood values and conditional likelihood ratio tests. Index terms: attitude measure ment, conditional likelihood ratio test, partial credit model, Rasch model, rating scales, successive inter vals, threshold model.
Theoretical predictions for the elliptical instability in a two-vortex flow

Two parallel Gaussian vortices of circulations Γ1 and Γ2 radii a1 and a2, separated by a distance b may become unstable by the elliptical instability due the elliptic deformation of their cores. The goal of the paper is to analyse this occurrence theoretically in a general framework. An explicit formula for the temporal growth rate of the elliptical instability in each vortex is obtained as a function of the above global parameters of the system, the Reynolds number Γ1/v and the non-dimensionalized axial wavenumber kzb of the perturbation. This formula is based on a known asymptotic expression for the local instability growth rate at an elliptical stagnation point which depends on the local characteristics of the elliptical flow and the inclination angle of the local perturbation wavevector at this point. The elliptical flow characteristics are estimated by considering each Gaussian vortex alone in a weak uniform external strain field whose properties are provided by a point vortex modelling of the vortex pair. The inclination angle is obtained from the dispersion relation for the Gaussian vortex normal modes and the local expression near each vortex centre for the two helical modes of azimuthal wavenumber m = 1 and m = −1 which constitute the elliptical instability global mode. Both the final formula and the hypotheses made for its derivation are tested and validated by direct numerical simulations and large-eddy simulations.
Dynamical Correlations for Globular Clusters in M31,

We present internal velocity dispersion measurements for a set of 21 globular clusters in the Andromeda galaxy (M31). We combine them with structural and photometric cluster parameters measured earlier with the Hubble Space Telescope and from the ground to explore correlations of cluster properties and to compare them with the equivalent correlations for the Galactic globular clusters. We find that the M31 globulars follow the same correlations between velocity dispersion and luminosity, central, and average surface brightness, as do their Galactic counterparts. This suggests a common physical origin for these correlations. They may be produced by the same astrophysical conditions and processes operating at the epoch of globular cluster formation in both galaxies. The very existence of these excellent correlations, and their quantitative form as scaling laws, represent challenges and constraints for theories of globular cluster formation. Preliminary estimates of the cluster M/L ratios show correlations with the cluster metallicity, in the sense of more metal-rich clusters having lower M/L, particularly in the near-infrared. At a given metallicity, there is no detectable systematic difference between the M31 globulars and their Galactic counterparts, which suggests a great similarity of their stellar populations. The observed scatter around these trends is comparable to the expected errors, which implies a small intrinsic scatter and thus which leaves little room for possible variations in the cluster age or stellar IMF at a given metallicity.
The Mind-Brain Problem and the Measurement Paradox of Quantum Mechanics: Should We Disentangle Them?

In recent decades, progress in the field of neurosciences has triggered an interest in understanding mind-brain relationships. Quantum Mechanics (QM) has been present in the debate from its beginnings through the well-known measurement paradox. The standard interpretation of QM considers two basic, fundamentally irreducible, processes: the deterministic evolution of the wave-function according to the Schrodinger equation, once the initial conditions have been settled; and the indeterministic wave-function collapse into one of the possible outcomes, after performing a specific measurement. So, QM would point to the limits of a purely deterministic view of nature and, in particular, of brains. Nevertheless, QM’s relevance for the brain’s physics is still to be proven. Detractors of the QM influence are confident of the role of decoherent processes at different physical scales in order to ensure a classical deterministic behavior of the brain. However, little attention is paid to the epistemic implications of invoking decoherence for the mind-brain problem. In this paper, (i) we present lasting QM models stating a specific view of human consciousness and make explicit their position regarding the relationship between the physical activity of neurons and/or networks of neurons and the phenomenal conscious experience; (ii) we review the main criticisms of the relevance of QM in the brain and, most importantly, we bring out the philosophical implications behind the usual recourse to decoherence in the transition from the quantum to the classical world, explaining why the mind-brain problem and the measurement paradox should not be disentangled.
G5.89-0.39: A compact H II region with a very dense circumstellar dust torus

We present the results of high angular resolution infrared observations of the compact H II region G5.89-0.39. Subarcsecond imaging at 1.65, 2.2, 3.6, and 4.8 microns and diffraction-limited scans at 50 and 100 microns have been obtained at NASA's Infrared Telescope Facility and Kupier Airborne Observatory and the Canada-France-Hawaii Telescope. We find a bipolar source morphology at the shortest infrared wavelengths, a compact single source at 4-5 microns, similar to that seen at 10 microns, and a very high optical depth, barely resolved far-infrared source. Spherical radiative transfer models have been used to estimate dust envelope properties; in spite of the obvious nonspherical geometry at short wavelengths, these models provide strong constraints on the overall properties of the circumnebular envelope. We find that the bulk of the circumstellar dust must be relatively close to the H II region, with a relatively steep gradient. The high column densities and steep density gradient imply densities at the inner edge of the cloud of order 10(exp 7)-10(exp 8)/cc. These results suggest that the compact H II region is surrounded by a very dense dust torus.
Subsonic gas flow in a straight and uniform microchannel

A nonlinear equation based on the hydrodynamic equations is solved analytically using perturbation expansions to calculate the flow field of a steady isothermal, compressible and laminar gas flow in either a circular or a planar microchannel. The solution takes into account slip-flow effects explicitly by utilizing the classical velocity-slip boundary condition, assuming the gas properties are known. Consistent expansions provide not only the cross-stream but also the streamwise evolution of the various flow parameters of interest, such as pressure, density and Mach number. The slip-flow effect enters the solution explicitly as a zero-order correction comparable to, though smaller than, the compressible effect. The theoretical calculations are verified in an experimental study of pressure-driven gas flow in a long microchannel of sub-micron height. Standard micromachining techniques were utilized to fabricate the microchannel, with integral pressure microsensors based on the piezoresistivity principle of operation. The integrated microsystem allows accurate measurements of mass flow rates and pressure distributions along the microchannel. Nitrogen, helium and argon were used as the working fluids forced through the microchannel. The experimental results support the theoretical calculations in finding that acceleration and non-parabolic velocity profile effects were found to be negligible. A detailed error analysis is also carried out in an attempt to expose the challenges in conducting accurate measurements in microsystems.
Discretized Gabor-based beam algorithm for time-harmonic radiation from two-dimensional truncated planar aperture distributions .I. Formulation and solution

In this first part of a two-paper sequence, we develop a Gabor-based Gaussian beam (GB) method for the representation of three-dimensional (3-D) time-harmonic vector electromagnetic fields excited by two-dimensional (2-D) truncated arbitrarily polarized planar aperture field distributions. The biorthogonal Gabor basis is tied to a lattice in the discretized four-dimensional (4-D) [configuration (space)]-[spectrum (wavenumber)] phase space which spans the 2-D aperture plane. This study generalizes previous investigations of the simpler corresponding procedure for 2-D fields excited by one-dimensional (1-D) apertures. By subsequent specialization, in the 1-D aperture case, to narrow-waisted 2-D ray-like GBs, we have shown that tracking such beams through interactions with complex environments and recombining them to synthesize the total 2-D field produces robust, efficient and accurate algorithms that are useful for a variety of forward and inverse scattering scenarios. Extension to the time domain via narrow-waisted pulsed GBs has likewise been considered. These potential applications have motivated the extension here to general 3-D EM fields excited by time-harmonic 2-D truncated apertures. The presentation relates each step in the analytic development to a corresponding step in the 1-D aperture case, thereby highlighting the complications (in the parameterizing phase space) associated with the 2-D aperture problem. The outcome is the formal exact solution of the problem under consideration.
Development of Frigate Designs with good Seakeeping Characteristics

Heading The paper summarises a design study of advanced mono-hull frigate concepts. Based on the parent design of a 120 m frigate, seven different alternatives of hull forms and concepts have been developed. The concepts have been evaluated according to their performance as regards a) ship motions in head, following and stern sea, b) linear operability for the North Atlantic and c) bare hull resistance and added power in head seas. The work was done as part of the THALES programme, which is a project with the Danish Naval Materiel Command (Denmark), FORCE Technology (Denmark), INSEAN (Italy), Italian Navy (Italy), MARIN (the Netherlands), Royal Netherlands Navy (the Netherlands) and Delft University of Technology (the Netherlands). The THALES programme has been completed in the period 2000-2004.
Prediction of turbulent offset jet flows with an assessment of QUICKER scheme

The QUICKER scheme extended for non-uniform rectangular grid systems has been applied to predict the turbulent offset jet flows. Computational results obtained with the QUICKER scheme are compared with those from the skew-upwind and the hybrid schemes. Computational results include the reattachment length, the velocity profile, the axial velocity decay curve, and the shear stress distribution. In the sense of an overall agreement with the experimental data, the QUICKER scheme is found to be superior to the other two schemes. Boundary conditions are carefully set up to account for various flow conditions. Special attention has been given to the set-up of entrainment boundary condition. It is emphasized that the numerical diffusion due to streamline-to-grid skewness far exceeds the turbulent diffusion in offset jet flows; therefore, a numerical scheme that would minimize the numerical diffusion is a prerequisite for a better prediction of the turbulent offset jet flows.
A model of toxoplasmosis incidence in the UK: evidence synthesis and consistency of evidence

Summary. We present a Bayesian evidence synthesis model combining data on seroprevalence, seroconversion and tests of recent infection, to produce estimates of current incidence of toxoplasmosis in the UK. The motivation for the study was the need for an estimate of current average incidence in the UK, with a realistic assessment of its uncertainty, to inform a decision model for a national screening programme to prevent congenital toxoplasmosis. The model has a hierarchical structure over geographic region, a random‐walk model for temporal effects and a fixed age effect, with one or more types of data informing the regional estimates of incidence. Inference is obtained by using Markov chain Monte Carlo simulations. A key issue in the synthesis of evidence from multiple sources is model selection and the consistency of different types of evidence. Alternative models of incidence are compared by using the deviance information criterion, and we find that temporal effects are region specific. We assess the consistency of the various forms of evidence by using cross‐validation where practical, and posterior and mixed prediction otherwise, and we discuss how these measures can be used to assess different aspects of consistency in a complex evidence structure. We discuss the contribution of the various forms of evidence to estimated current average incidence.
Gauge invariance of Landau levels

The eigenfunctions of the Hamiltonian for a charged particle in a magnetic field are obtained in an arbitrary gauge by use of algebraic methods. Due to the degeneracy of each Landau level, additional operators must be diagonalized in order to completely specify each eigenstate. In this way all the eigenfunctions are separated into two classes where every member within the same class transforms by a simple phase factor under a gauge transformation. Relations are also established between the functions belonging to different classes of solutions.
Interlaminar Stresses in Composite Laminates Subjected to Anticlastic Bending Deformation

Approximate elasticity solutions for prediction of the displacement, stress, and strain fields within the m-layer, symmetric and balanced angle-ply composite laminate of finite-width and subjected to uniform axial extension and uniform temperature change were developed earlier by the authors. In the present paper, the authors have extended these solutions to treat bending deformation. Bending and torsion moments are combined to yield a deformation state without twisting curvature and with transverse curvature due only to the laminate Poisson effect. This state of deformation is termed anticlastic bending. The approximate elasticity solution for this bending deformation is shown to recover laminated plate theory predictions at interior regions of the laminate and thereby illustrates the boundary layer character of this interlaminar phenomenon. The results exhibit the anticipated response in congruence with the solutions for uniform axial extension and uniform temperature change, where divergence of the interlaminar shearing stress is seen to occur at the intersection of the free edge and planes between lamina of +θ and –θ orientation. The analytical results show excellent agreement with the finite-element predictions for the same boundary-value problem and thereby provide an efficient and compact solution available for parametric studies of the influence of geometry and material properties. Finally, the solution was exercised to determine the dimensions of the boundary layer in bending for very large numbers of layers.
Local flow properties at a viscous free surface

A local analysis has been made about a point at the free surface of an incompressible viscous fluid flow at steady state by means of series expansions of the Navier–Stokes equations. Dividing streamlines, curvature effects, and the role of vorticity have been studied. A single dividing streamline is always perpendicular to the free surface. This means, in particular, that all steady vortices with one end of their axes attached to a free surface are perpendicular to it. Double dividing streamlines of two‐dimensional viscous fluid flows at a free surface always have an angle of 90° between them, whereas double dividing streamlines of inviscid irrotational motion on a free or solid surface are separated by an angle of 60°. For an interface between two immiscible viscous fluids a novel ‘‘refraction law’’ for dividing streamlines has been derived.
On the motion of suspended sand particles

The motion of suspended sand particles is studied by means of a new perturbation solution to the equation of motion. In the first approximation, fluid accelerations are neglected so that the relative velocity between sand and water is everywhere equal to the still water settling velocity . It turns out that some of the most important mechanisms of sediment suspension, such as trapping in vortices, can be derived from this “zero order solution” when the flow structure is given proper consideration. The next level of solutions takes into account the effect of fluid accelerations by including terms of order of magnitude . As a main result it is shown that pure wave motion does not cause a net reduction of settling velocity of this order of magnitude. Finally the effect of drag nonlinearity is studied for the case of an oscillatory flow. It is shown that this effect is of the order of magnitude e2 and without practical importance for sediment suspension by waves.
Hubble Space Telescope Observations of the Hubble Clusters in NGC 6822: Ages and Structure

We present Hubble Space Telescope observations of four cluster candidates in NGC 6822 originally identified by Hubble. One of them, Hubble IV, is an H ii region while Hubble VI, VII, and VIII are confirmed as rich star clusters. Based upon cluster color‐magnitude diagrams from which the field star contamination has been subtracted, we derive ages of 70 ± 10 Myr for Hubble VI and 1.5 ± 0.2 Gyr for Hubble VIII. While the age is more uncertain in the case of Hubble VII, the available evidence argues that this cluster is probably similar to the old, metal‐poor globular clusters in the Milky Way. Comparisons of the cluster ages and integrated magnitudes with models of cluster evolution imply that the two young clusters are an order of magnitude less massive than the older cluster Hubble VII. The radial profiles of all three clusters are reasonably well fit by empirical King models. The core radius and central surface brightness of Hubble VII are consistent with observations of Galactic globular clusters. The half‐light radii of these clusters are comparable to values for the inner Milky Way globulars and are on average smaller than clusters in the Magellanic Clouds. These clusters apparently are exceptions to the trend noted by van den Bergh that larger clusters tend to form in environments with lower stellar densities.
On the dynamical sliding mode control of nonlinear systems

The consequences of the differential algebraic approach in the sliding mode control of nonlinear single-input single-output systems are reviewed in tutorial fashion. Input-dependent sliding surfaces, possibly including time derivatives of the input signal, are shown to arise naturally from elementary differential algebraic results pertaining to the Fliess's Generalized Controller Canonical Forms of nonlinear systems. This class of switching surfaces generally leads to chattering-free dynamically synthesized sliding regimes, in which the highest time derivative of the input signal undergoes all the bang-bang type discontinuities. Examples illustrating the obtained results are also included.
On the Accuracy of Omega Diagnostic Computations

Abstract The accuracies of algorithms used to compute quasi-geostrophic diagnostic parameters such as Hoskins' Q-vector and its divergence are evaluated. Analytically-determined height values are invoked at grid points representing three pressure surfaces, and finite difference approximations to third and lower order derivatives are compared with analytic values. Errors from these approximations are found to be virtually identical to those predicted by a mathematical analysis of the centered difference scheme. The magnitudes of finite difference errors are a function of wavelength, being acceptably small for waves sampled nine or more times per wavelength. Interpolation of grid point values from analytically determined observations at a typical array of rawinsonde stations produces diagnostic results that, while they contain many distortions owing mainly to data sparseness still contain significant portions of the signal, as determined by a two-dimensional spectral estimation technique using Fourier analy.
Fiber-based 1.5 μm lidar vibrometer in pulsed and continuous modes

A fiber-based 1.5 μm heterodyne lidar that is easily switched between pulse-pair and cw modes is described. In laboratory experiments using well-controlled vibrating targets, and in computer simulations, the performance of the two modes is compared given the same average laser power. The accuracy of Doppler frequency (target velocity) estimates, and the signal-to-noise ratio in spectrally resolved plots of vibrational features, are evaluated. When the target-induced frequency modulation is wideband, pulse-pair often has clearly higher carrier-to-noise. But its advantage in signal-to-noise is smaller because combining the more numerous cw measurements improves the estimates of vibration frequencies and amplitudes. They are combined here through autocorrelation-based demodulation, one of several methods that can outperform phase-differencing.