Miracle-dz/UniFAR-FTUs huggingface dataset:
Numerical Analysis of the Three-Dimensional Swirling Flow in Centrifugal Compressor Volutes

The improvement of centrifugal compressor performance and the control of the radial forces acting on the impeller due to the circumferential variation of the static pressure caused by the volute require a good understanding of the flow mechanisms and an accurate prediction of the flow pattern inside the volute. A three-dimensional volute calculation method has been developed for this purpose. The volute is discretized by means of hexahedral elements. A cell vertex finite volume approach is used in combination with a time-marching procedure. The numerical procedure makes use of a central space discretization and a four-step Runge-Kutta time-stepping scheme. The artificial dissipation used in the solver is based on the fourth-order differences of the conservative variables. Implicit residual smoothing improves the convergence rate. The loss model implemented in the code accounts for the losses due to internal shear and friction losses on the walls. A comparison of the calculated and measured results inside a volute with elliptical cross section reveals that the modified Euler solver accurately predicts the velocity and pressure distribution inside and upstream of the volute.
A two-dimensional uniplanar transmission-line metamaterial with a negative index of refraction

A uniplanar transmission-line (TL) network has been loaded with lumped elements (chip or printed), enabling one to achieve a two-dimensional (2D) uniplanar negative-refractive-index (NRI) metamaterial. The metamaterial consists of a 2D array of unit cells, composed of TL sections connected in series and loaded in a specified manner. The unit cell dimensions can be designed to be much smaller than the operating wavelength, enabling one to identify the structure as an effective medium, with a negative index of refraction. This NRI metamaterial supports transverse electric (TE) waves, as opposed to related previous work on NRI-TL media that supported transverse magnetic (TM) waves. The dispersion characteristics are calculated using a simple, fast 2D loaded TL model with periodic (Bloch) boundary conditions. Subsequently the dispersion relation is simplified in the homogeneous limit, thus allowing one to identify effective permittivities and permeabilities, which are shown to be simultaneously negative. Simulations demonstrating the negative refraction of a plane wave on an interface between such a NRI uniplanar metamaterial and a commensurate positive-refractive-index (PRI) metamaterial verify the validity of the proposed concept and theory. A fully printed unit cell is presented at microwave frequencies (∼10 GHz) along with a prescription for synthesizing an isotropic 3D transmission line NRI metamaterial based on this unit cell.
Comment on a Paper by Singh and Ullah

It is shown that the words ‘far weaker’ used four times by Singh and Ullafa [4] in describing their mixing condition in relation to ones of Robinson [1] for establishing the central limit theorem for nonparametric estimators, should in each case be replaced by theword ‘stronger,’ Singh and Ullah's [4] condition being equivalent to complete independence across time.
A model for the effects of dust on the spectra of disk galaxies. I: General treatment

Formulation du probleme de transfert radiatif dans le cas des galaxies a disques avec la description d'une technique d'integration numerique appropriee. L'effet de la diffusion et de l'absorption interstellaire est ainsi determine et exprime sous forme de facteurs de correction en fonction de la longueur d'onde, de l'angle d'inclinaison et de la profondeur optique
Transition to a wavy vortex régime in convective flow between inclined plates

Experimental results concerning the supercritical behaviour of instabilities occurring in the thermal convective flow between inclined plates are presented. For inclination δ between 90° and 10° (δ = 0° is the vertical orientation), with the bottom plate hotter, it is known that the primary instabilities are longitudinal convective rolls with axes oriented up the slope. These rolls are found to become wavy at a supercritical Rayleigh number Ra(δ, Pr), with an upslope wavelength which seems to be related directly to the wavelength of the original rolls. Measurements indicate that these transitions take place at Reynolds numbers which are probably too small for the process to be attributed to a shear instability. It is thought that the cross-slope derivative of the buoyancy force, which exists because of the tilted geometry, is important in generating the required vorticity. The transition is crucial to the development of violent unsteadiness. The breaking of the waves leads to turbulence at much lower Rayleigh numbers than those required in convection between horizontal plates. The transition to wavy vortices appears to be very similar to that which occurs for Taylor vortices in cylindrical Couette flow.
A survival‐adjusted quantal response test for comparing tumour incidence rates

Summary. The paper presents a case‐study of skin fibromas among male rats in the 2‐year cancer bioassay of methyleugenol that was conducted by the US National Toxicology Program (NTP). In animal carcinogenicity experiments such as this one, tumour rates are often compared with the Cochran–Armitage (CA) trend test. The operating characteristics of the CA test, however, can be adversely affected by survival differences across groups and by the assumed dose metric. Survival‐adjusted generalizations of the CA test have been proposed, but they are still sensitive to the choice of scores that are assigned to the dose groups. We present an alternative test, which outperforms the survival‐adjusted CA test which is currently used by the NTP to compare incidence rates. Simulated data from a wide range of realistic situations show that the operating characteristics of the test proposed are superior to those of the NTP's survival‐adjusted CA test, especially for rare tumours and wide logarithmic spacings of the dose metric.
A comparison of class‐wide taped problems and cover, copy, and compare for enhancing mathematics fluency

An adapted alternating treatments design was used to compare the effects of class-wide applications of Taped Problems (TP) and Cover, Copy, and Compare (CCC) procedures designed to enhance subtraction fact fluency in an intact third-grade classroom. During the TP procedure, a tape provided an auditory prompt (i.e., the problem), followed by a 2-second delay and then the correct answer. Students attempted to supply the correct answer before the answer was provided by the tape. During the CCC procedure, students would cover a math-fact family triangle, attempt to write one of two possible problems and answer, write the reciprocal fact and answer, and evaluate their responses. Results show that TP caused greater increases in subtraction fact fluency than CCC or a control condition. Discussion focuses on preventing student math deficits, issues regarding alternating treatments designs, and future directions for research. © 2012 Wiley Periodicals, Inc.
Transit timing variation and activity in the WASP-10 planetary system

Transit timing analysis may be an effective method of discovering additional bodies in extrasolar systems which harbour transiting exoplanets. The deviations from the Keplerian motion, caused by mutual gravitational interactions between planets, are expected to generate transit timing variations of transiting exoplanets. In 2009 we collected 9 light curves of 8 transits of the exoplanet WASP-10b. Combining these data with published ones, we found that transit timing cannot be explained by a constant period but by a periodic variation. Simplified three-body models which reproduce the observed variations of timing residuals were identified by numerical simulations. We found that the configuration with an additional planet of mass of �0.1 MJ and orbital period of �5.23 d, located close to the outer 5:3 mean motion resonance, is the most likely scenario. If the second planet is a transiter, the estimated flux drop will be �0.3 per cent and can be observable with a ground-based telescope. Moreover, we present evidence that the spots on the stellar surface and rotation of the star affect the radial velocity curve giving rise to spurious eccentricity of the orbit of the first planet. We argue that the orbit of WASP-10b is essentially circular. Using the gyrochronology method, the host star was found to be 270 ± 80 Myr old. This young age can explain the large radius reported for WASP-10b.
A Determinant Maximization Problem Occurring in the Theory of Data Communication

Let H be a Hermitian $m \times m$ matrix, with eigenvalues $\lambda _1 \geqq \lambda _2 \geqq \cdots \geqq \lambda _m \geqq 0$ of which $m^ + \geqq 1$ are positive. Then the maximum of $\det ( {I_n + GHG^ * } )$ over all complex $n \times m$ matrices G) satisfying trace $GG^ * \leqq 1$ is \[ r^{ - r} \left( {1 + \mathop \Sigma \limits_{i = 1}^r \lambda _i^{ - 1} } \right)^r \mathop \Pi \limits_{j = 1}^r \lambda _j , \] where r is the largest integer satisfying $r\leqq n,r\leqq m^ + $, and $r< \lambda _r ( {1 + \Sigma _{i = 1}^r \lambda _i^{ - 1} } )$ . The matrices G for which the maximum is attained are characterized. They have rank r. A special case of this problem arises in the optimization of certain data communication systems.
Dynamics of an axisymmetric body spinning on a horizontal surface. III. Geometry of steady state structures for convex bodies

Following parts I and II of this series, the geometry of steady states for a general convex axisymmetric rigid body spinning on a horizontal table is analysed. A general relationship between the pedal curve of the cross-section of the body and the height of its centre-of-mass above the table is obtained which allows for a straightforward determination of static equilibria. It is shown, in particular, that there exist convex axisymmetric bodies having arbitrarily many static equilibria. Four basic categories of non-isolated fixed-point branches (i.e. steady states) are identified in the general case. Depending on the geometry of the spinning body and its dynamical properties (i.e. position of centre-of-mass and inertia tensor), these elementary branches are differently interconnected in the six-dimensional system phase space and form a complex global structure. The geometry of such structures is analysed and topologically distinct classes of configurations are identified. Detailed analysis is presented for a spheroid with displaced centre-of-mass and for the tippe-top. In particular, it is shown that the fixed-point structure of the flip-symmetric spheroid, discussed in part I, represents a degenerate configuration whose degeneracy is destroyed by breaking the symmetry. For the spheroid, there are in general nine distinct classes of fixed-point structures and for the tippe-top there are three such structures. Bifurcations between these classes are identified in the parameter space of the system.
Retrieval properties of attractor neural networks that obey Dale's law using a self-consistent signal-to-noise analysis

The recently proposed self-consistent signal-to-noise analysis is applied to a current–rate dynamics attractor network of excitatory neurons with a Hebbian synaptic matrix. The effect of inhibitory interneurons is included by a term modelling their effective inhibition that depends upon both the level of activity of the excitatory neurons and the stored patterns. The low rate attractor structure is identified, and at low loading the network retrieves single patterns with uniform low rates without errors, and is stable to the admixture of additional patterns. The self-consistent signal-to-noise method enables the analysis of the network properties with an extensive number of patterns, and the results are compared with simulations. The method allows the identification of the fixed point structure of networks for which there is no Lyapanov function, and hence for which mean-field techniques cannot be used. This analysis is shown to provide a powerful and straightforward way of analysing the properties of net.
Estimating stochastic differential equations efficiently by minimum chi-squared

We propose a minimum chi-square estimator for the parameters of an ergodic system of stochastic differential equations with partially observed state. We prove that the efficiency of the estimator approaches that of maximum likelihood as the number of moment functions entering the chi-square criterion increases and as the number of past observations entering each moment function increases. The minimized criterion is asymptotically chi-squared and can be used to test system adequacy. When a fitted system is rejected, inspecting studentized moments suggests how the fitted system might be modified to improve the fit. The method and diagnostic tests are applied to daily observations on the U.S. dollar to Deutschmark exchange rate from 1977 to 1992. Key Words: Diffusions, efficiency, estimation, exchange rate, minimum chi-square, partially observed state, simulation, specification test, stochastic differential equation.
The effects of the distribution of residual magnetization on the cogging torque and switching signals in permanent magnet (PM) motors

A novel cogging torque reduction method is presented for permanent magnet (PM) motors. The key idea of the method is optimizing the distribution of residual magnetic flux density of the PM by putting auxiliary slots on the pole face of the magnetizing yoke. Through the three-dimensional (3-D) finite-element simulation with edge elements and nodal force method for the motor having eight PM poles and six winding slots, the effectiveness of the presented method is proved. The effects on the switching signal are also investigated.
Sea‐ice and the antarctic winter circulation: A numerical experiment

A numerical experiment has been conducted to test the sensitivity of a global general circulation model to changes in sea-ice extents in the antarctic during winter. Three 112-day integrations have been made in which all the antarctic sea-ice poleward of 66°S was removed, commencing on 10 June in the second, third and fourth years of a control integration. There was a large increase in sensible heat flux over the anomaly, a warming over the antarctic confined to the lowest atmospheric layer, and a 2ms−1 reduction in the westerly flow around the periphery of the (new) sea-ice margin, in broad agreement with a previous study by I. Simmonds. The increased heating over the anomaly was accompanied by a decrease in surface pressure which was not found by Simmonds, and possible explanations of this discrepancy are considered. The results are related to previous work on the effect of increased CO2 using prescribed changes in sea surface temperature and sea-ice extents. The implications of the results for the parametrization of the heat flux through sea-ice cover, and for coupled ocean-atmosphere models are discussed.
A Poisson Regression Model of Tropical Cyclogenesis for the Australian–Southwest Pacific Ocean Region

Abstract This paper seeks to address some of the limitations in previous statistical forecast models of tropical cyclogenesis through the development of a series of Poisson regression models on a 2° latitude × 5° longitude spatial grid and a monthly grid in time. The “Gray” parameters [low-level relative vorticity, vertical wind shear parameter, ocean thermal energy, (saturated) equivalent potential temperature gradient, and middle-troposphere humidity] were analyzed as potential predictors of tropical cyclogenesis for the Australian–southwest Pacific Ocean region. Various predictor lead times of up to 5 months were investigated, with the most significant Poisson regression models being cross validated, and the skill of their hindcasts evaluated. The Poisson regression model incorporating a combination of saturated equivalent potential temperature gradients at various leads was found to be the most skillful in hindcasting the temporal (phase and amplitude) variability of tropical cyclogenesis for the Aust.
Ion reflection and dissipation at quasi‐parallel collisionless shocks

Large scale one-dimensional hybrid simulations have been performed of a quasi-parallel (ΘBn = 20°) high Mach number collisionless shock. It is found that backstreaming reflected ions, i.e., upstream ions with velocities exceeding the shock ram velocity, originate from the outer part (v≳ 1.7vth) of the velocity space of the incident distribution. The backstreaming ions produce very low-frequency magnetosonic waves which propagate upstream with about 1.3VA (Alfven speed). As the wave crests convect toward the shock, they steepen up and the shock reforms itself. During shock reformation a large part of the incident ions are reflected. This, in turn, slows the incident ions down. The slowed down incident particle distribution and the reflected particle distribution merge and constitute the new thermalized downstream distribution. In the interval of a relatively stationary shock low-frequency whistler waves stand at the shock front. During these time intervals the whistler waves are probably responsible for dissipation by nonadiabatic compression of the incident ions. The whistler waves are destroyed by the incoming large amplitude wave crest and reemerge at the new shock front. The reapparance seems to be due to the nonlinear steepening of the incoming wave crest at the upstream side.
A Gaussian model approach for the prediction of speckle reduction with spatial and frequency compounding

In the past different analytical expressions have been derived to describe the correlation curve /spl rho/(/spl Delta/x) of two ultrasonic images which are created from a set of subapertures for spatial compounding or a set of subbands for frequency compounding. We show that both speckle reduction with spatial compounding (SC) and with frequency compounding (FC) can be modeled by a Gaussian shaped correlation curve of the kind /spl rho/(/spl Delta/x)=exp(-/spl Delta/x/sup 2///spl alpha/), where /spl Delta/x represents either the relative shift between neighboring subapertures or neighboring subbands and the parameter /spl alpha/ is a constant which describes the inherent properties of the two compounding algorithms. With our experiments the parameter /spl alpha/ is estimated individually for SC and FC and the model is used to determine the optimum number of subimages to obtain maximum lesion detectability with a predefined loss in resolution. The results are compared with experimental data.
A Unified Account of Quantifer Perspective Effects in Discourse

Positive and negative quantifiers induce two very different perspectives in comprehenders—perspectives that have strong applications to rhetoric and communication. These are briefly reviewed. A potential mechanism, based on earlier work, is introduced, resting on the idea that negatively quantified sentences (like Not all of the boys went to the party) may be given interpretations that both consist of an asserted amount, and a supposition of a greater amount. This account, the supposition-denial theory, is proposed as a unifying mechanism that explains the variety of perspective effects. Straightforward predictions from this account are tested in three studies. In particular, we found that a linguistic index of denial almost perfectly predicted the incidence of particular kinds of focus effects (Study 1 and 3). We also show that the observed perspectives set up by negative quantifiers depend upon the whole quantified sentence being processed, not just the quantifier (Study 2). This is consistent with the denial aspect being central to perspective. We discuss how positive quantifiers may also be treated within the framework, leading to independently confirmed predictions. Finally, we discuss the relation of our account to current work in pragmatics and semantics.
Near-infrared adaptive optics dissection of the core of NGC 1068 with NAOS-CONICA

We present an update analysis of recent near-infrared adaptive optics observations of NGC 1068 obtained with NAOS-CONICA at VLT/UT4. Ks, Land Mbands images were deconvolved using MISTRAL, a regularized algorithm based on a maximum a posteriori estimation of the object. Two regularization methods, one including a new maximum likelihood estimation of the object Power Spectral Density, and an edge preserving one, have been tested and converge to consistent results. The deconvolved images show a coherent evolution of the IR emission from 2.2 to 4. 8µm. Deconvolution brings new elements: a) it strengthens the very peculiar nature of the four parallel elongated nodules previously discovered along the jet, which appear unresolved perpendicular to their long axis; b) it underlines the strong correlation between UV clouds and IR features, and c) it provides a more accurate multi-wavelength registration of the actual active nucleus. The overall aspect of the central 1 �� ×1 �� IR emission seems to point to the jet as a major mechanism to shape the NLR. For each identified structure, we derive a color temperature now based on three bands (M, L and K), before and after deconvolution, confirming the need for clumps of dust at unexpectedly high and almost constant temperature (about 500 K) up to 70 pc north of the nucleus. We explore several mechanisms to explain the color temperature and show that shocks, induced for instance by the interaction of the jet with a giant cloud, is unlikely to be the dominating mechanism to heat the dust. We detail our model of transient heating of Very Small Grains and show that it can provide a consistent explanation of the K, L, M colors and their lack of variation with distance when 0.6 nm diamond-like grains are heated by 4 to 8 eV UV photons. However, we do not exclude the possibility that part of the excitation could come from shocks. At Ks, deconvolution reinforces the previous claim that the central core is partially resolved along the N-S direction: the best fit to our data is an elliptical Gaussian extended along PA = −16 with a 2.1 pc FWHM along this direction. This result agrees with the predictions of the radiative transfer model we previously developed to interpret the spectroscopic behavior at K, and is consistent with VLTI/VINCI measurements. Several questions are raised by this study: a) is the jet dominant in shaping the NLR of this AGN? b) what is the real state of the dust in the environment of the core; c) is the simple doughnut torus model able to explain IR emission of the central source with a morphology that appears increasingly complex at small scale?
Scale analysis of miscible density-driven convection in porous media

Abstract Scale analysis of unstable density-driven miscible convection in porous media is performed. The main conclusions for instabilities in the developed (long time scales) regime are that (i) large-scale structures are responsible for the bulk of the production of concentration variance, (ii) variance dissipation is dominated by the small (diffusive) scales and that (iii) both the production and dissipation rates are independent of the Rayleigh number. These findings provide a strong basis for a new modelling approach, namely, large-mode simulation (LMS), for which closure is achieved by replacing the actual diffusivity with an effective one. For validation, LMS results for vertical flow in a homogeneous rectangular domain are compared with direct numerical simulations (DNS). Some of the analysis is based on the derivation and closure of the concentration mean and variance equations, whereby averaging over the ensemble of all possible initial perturbations is considered. While self-similar solutions are obtained for vertical, statistically one-dimensional fingering, triple correlation of concentration and scalar dissipation rate (rate at which the concentration variance decays due to diffusion) have to be modelled in the general case. For this purpose, an ensemble-averaged Darcy modelling (EADM) approach is proposed.