Miracle-dz/UniFAR-FTUs huggingface dataset:
Reduction of cogging torque in permanent magnet motors

Cogging torque in a permanent magnet motor, which arises from the interaction of the rotor magnets with the steel teeth on the stator, can be reduced by skewing the stator teeth, but only at the expense of added complexity in stator construction and some loss of output torque. It is shown that by appropriate choice of the angular width of the magnet relative to the tooth-plus-slot dimension, the cogging torque can be reduced to about 1% of rated torque. A further reduction to about 0.3% resulted from a rotational shift of one pair of poles with respect to the other pair in a four-pole motor. The analysis of cogging torques with both surface mounted and inset magnet rotors as well as experimental confirmation are reported. >
Projection estimates of multivariate location

In this paper we study the maximum asymptotic bias of the projection estimate for multivariate location based on univariate estimates of location and dispersion. In particular we study the projection estimate that uses the median and median absolute deviation about the median (MAD) as univariate location and dispersion estimates respectively. This estimator may be considered a natural affine equivariant multivariate median. For spherical distributions the maximum bias of this estimate depends only on the marginal distributions, and not on the dimension, and is approximately twice the maximum bias of the univariate median. We also show that for multivariate normal distributions, its maximum bias compares favorably with those of the Donoho-Stahel, minimum volume ellipsoid and minimum covariance determinant estimates. In all these cases the maximum bias increases with the dimension p.
On involutive Lie algebras having a Cartan decomposition

We introduce the concept of Cartan decomposition relative to a Cartan subalgebra H in the sense of Y. Billig and A. Pianzola for involutive complex Lie algebras L of arbitrary dimension. If L has such a decomposition and is infinite dimensional and simple, we show it is *-isomorphic to a direct limit of classical finite dimensional simple involutive Lie algebras of the same type A, B, C, or D.
Nonlinear Vibration Analysis of Simply Supported Stiffened Plate by a Variational Method

Large-amplitude free vibration analysis of uni-axially single stiffened rectangular plates subjected to transverse loading with simply supported boundary conditions has been presented. The mathematical formulation is based on energy principle. Geometric nonlinearity is accounted for by consideration of nonlinear strain-displacement relations. The static problem is solved through an iterative scheme and the dynamic problem is solved with the static displacement field as an initial guess. Influence of stiffener position, plate aspect ratio, and stiffener to plate thickness ratio on the large amplitude dynamic behavior has been studied. The dynamic behavior has been furnished in the form of backbone curves in a dimensionless frequency-amplitude plane.
Depressed index substrate tubes to eliminate leaky-mode losses in single-mode fibers

Silica tubing to be used as substrate tubes for MCVD has was demonstrated for a fiber having only one-fourth the deposited clad-merical tubing in that it is both dehydrated and fluorinated during processing to yield a silica which is dry and whose refractive index is lower than that of silica. These tubes are advantageously used to prepare single-mode fibers having fluorinated-silica cladding which controls dispersion and reduces scattering losses. In this case, the refractive index of the deposited cladding can be matched to that of the outer tube thus avoiding leaky-mode losses commonly encountered in depressed-index clad fibers. Using such an approach, low loss (0.28 dB/km at 1.55 μm) was demonstrated for a fiber having only one-fourth the deposited cladding required when a commercial silica tube is used. Such tubes could provide ecomomies to the processing of and the performance of complex cladding single-mode structures and impact multimode fiber designs.
A theoretical study of the Brinell hardness test

Brinell tests have long been the preferred method of assaying the hardness of metals during forming operations. The general significance of the test has been codified in empirical laws, especially those of Meyer, O’Neill and Tabor. On the other hand, the indentation of elastoplastic media by a ball has never been thoroughly analysed in the context of modern mechanics of continua; this is the objective here. The actual boundary-value problem is non-steady but can be made steady in terms of reduced variables when the material response is suitably modelled. Namely, the strain should be infinitesimal and expressible as the tensor gradient of a potential function of the stress deviator; the function must be homogeneous of degree n+1 (≥ 2), but is otherwise arbitrary. Meyer’s law is then derivable rigorously ahead of a detailed solution. Moreover the predicted index is (2n+1)/n, substantiating O’Neill’s rule for materials whose strain under uniaxial tension varies as some nth power of the stress. It is predicted also that the piling-up or sinking-in around the indenter is correlated with n in the manner observed. These immediate implications of the model amount to a priori evidence of its overall ability to simulate elastoplastic response of the kind induced in Brinell tests. Evidence a posteriori was supplied by finite element computations for a standard potential whose level surfaces are of Mises type. Mixed nine-node quadrilateral elements were adopted; these are known to promote optimal convergence and are well suited to handling incompressibility. A carefully graded mesh provided about 24000 degrees of freedom. Computations were performed for n ═ 1, 2, 4 and 10, covering the practical range. The results include (i) distributions of the contact pressure and the radial and circumferential in-surface stresses; (ii) profiles of the deformed surface; and (iii) contours of representative strain in the main body of material. Excellent agreement was obtained with Tabor’s experimental findings that the representative strain at the contact perimeter is γ ═ 0.4 a/D for any n (a is the contact radius and D the ball diameter), while the average pressure is 2.8 times the flow stress at strain γ in a tension test. Finally, strain paths at fixed stations were sampled to check the simulation of elastoplastic response locally as well as overall.
Field studies of the optical and microphysical characteristics of clouds enveloping Great Dun Fell

In an effort to study aspects of their evolution, simultaneous measurements have been made, in two separate studies, of the microphysical properties of cap clouds over Great Dun Fell, in Cumbria, at two vertically displaced sites along the line of the wind. Dynamical, optical (10.6 γm) and acoustic sounder measurements were also made. Influences upon the cloud properties of humidity fluctuations near to cloud base, turbulent deposition of droplets to ground, additional activation caused by orographically induced accelerations within the clouds, entrainment of environmental air and long-wave radiation to space were identified and examined. The clouds studied exhibited structure in their microphysical and optical properties on all scales from a few metres to several hundred metres. The cloud model of Carruthers and Choularton was found to predict the optical and microphysical characteristics of clouds not significantly influenced by entrainment, to a reasonable degree of accuracy.
Time to Failure and Availability of Paralleled Systems with Repair

This paper discusses reliability properties of some simple paralleled or redundant systems, where repair is possible in case of failure. We are assuming here that a ``failure'' may always be instantly identified, and the appropriate steps taken. In certain problems such an assumption is not warranted. The ``systems'' discussed are composed of two identical ``subsystems,'' e.g., computers, or radars, and the system is considered to be in a state of failure when, and only when, both subsystems are simultaneously in such a state. Such system design strategies have been proposed for various applications, but have received little analysis. Two measures of reliability are discussed: 1) the time to system failure, measured from an instant at which both subsystems are operative, and 2) the long-run availability of the system, where the latter means the average fraction of the time during which the system is able to perform its function. Analysis is based on the assumption of ``random'' (Poisson-like) failure for the subsystems (for theoretical justification see Drenick [2]), and independent but otherwise arbitrarily distributed repair times. It is of some interest that several of the important operational measures deduced, depend in detail upon the form of the distribution of repair times, as it is summarized in its Laplace transform, and not simply upon certain simple averages or moments of repair time.
Elliptical Galaxies Since z ~ 1.5: The Evolution of The Fundamental Planes

Abstract We use a set of hydrodynamical, self consistent simulations operating in the context of a concordance cosmological model where relaxed elliptical-like objects (ELOs) were identified at different redshifts. ELOs at different redshift are well described by the Sérsic (1968) function. We also obtain a good comparison with observational scaling relations. These results indicate that ELOs conform a homogeneous population at any redshift, except that high z ELOs tend to be more compact that their lower z counterparts. Also, scaling relations point to the rupture of the structural homology.
The evolution of the coherent structures in a uniformly distorted plane turbulent wake

A plane turbulent wake generated by a flat plate is subjected to a uniform distortion. It is observed that nearly two-dimensional, quasi-periodic coherent structures dominate the distorted wake. Rapid distortion theory, applied to a kinematic vortex model of the coherent structures in the undistorted far wake, predicts many of the effects revealed by a hot-wire anemometry/pattern-recognition analysis of these structures. Specifically, rapid distortion theory predicts reasonably well the observed changes in the ensemble-averaged velocity patterns and the disproportionate amplification of the large-scale coherent structures relative to the smaller-scale ‘isotropic’ eddies. These results are consistent with the view that self-preservation of the distorted wake is not possible because of the selective amplification of the coherent structures, which control the development of the wake. As well, the entrainment rate in the distorted wake increases at a rate greater than that predicted by the self-preservation theory.
Activity evolution, outburst, and splitting events of comet 73P/Schwassmann-Wachmann 3

Context. The split Jupiter family comet 73P/Schwassmann-Wachmann 3 was monitored between January 21 and May 25 2006, for 24 nights. Aims. The goals of the campaign were to characterize the two principal comet components (C and B) and the smaller component G during their approach to perihelion, and study differences and commonalities in their evolution to obtain insight into the nature of the nuclei (gas and dust). We aimed to assess the chemical homogeneity/heterogeneity of the different components, the presence of jets and other coma structures, the rotation axis, the long-term activity evolution, and the detection of new fragmentation events. Methods. Long-slit spectra and optical broadband images were acquired using the CAFOS instrument at the 2.2-m telescope at Calar Alto Observatory (CSIC-MPG). Data obtained in service mode consisted of spectra and Johnson R filter images. By observing for four nights close to perigee, the comet could be imaged in the Johnson UBVRI filters. When possible, we analyzed the radial profile of the dust brightness and we derived the dust and gas production rates, the dust reddening, and the N-S profiles of the CN, C2, and C3 column densities. The analysis of the morphological evolution of coma structures and the determination of the rotation axis is performed in a separate paper. Results. We found that components C and B behave differently during most of our observations. While component C did not show any sudden increase in dust productivity, as measured by Afρ, component B was characterized by a higher activity variation, exhibiting two outburst peaks and fragmentation events. Excluding outburst dates, component B always had lower dust productivity than component C. We also found differences in the behavior of the dust brightness radial profiles and in the dust colors. Differences in the dust colors are found also with respect to component G. In the spectral analysis, we found that both C and B components seem to be carbon-chain depleted, their compositions being almost the same. This indicates that the pre-split original intact nucleus probably had a homogenous composition. A two-dimensional color map of component B on May 13 shows relative color variations in the inner coma that can be interpreted qualitatively in terms of Mie theory as fragmentation of silicate dust particles emanating from the nucleus.
A highly effective preconditioner for MoM analysis of large slot arrays

A highly effective preconditioner is presented to solve the system of equations obtained from the application of the moment methods to slotted waveguide array antenna problems. This preconditioner accounts for the near field (expansion function - testing function) interactions for a given basis function on a slot. When conjugate gradient method is employed to solve the preconditioned system equation, the convergence can be greatly accelerated. Numerical results show that the proposed preconditioner can improve the convergence of an iterative solution by an order of magnitude for large slot arrays.
Highly efficient estimators of multivariate location with high breakdown point

We propose an affine equivariant estimator of multivariate location that combines a high breakdown point and a bounded influence function with high asymptotic efficiency. This proposal is basically a location $M$-estimator based on the observations obtained after scaling with an affine equivariant high breakdown covariance estimator. The resulting location estimator will inherit the breakdown point of the initial covariance estimator and within the location-covariance model only the $M$-estimator will determine the type of influence function and the asymptotic behaviour. We prove consistency and asymptotic normality and obtain the breakdown point and the influence function.
Analyses of Fish Species Richness with Spatial Covariate

Abstract Legislation passed in 1990 reducing the allowable sulfur dioxide emission levels in the United States is expected to reduce acidity in the Adirondack region of New York State. The number of fish species in a lake (species richness) depends on a number of physical and chemical factors, including the area, elevation, and acidity of the lake. Data on these and other factors are available for 1,166 Adirondack lakes. The data are analyzed with the goal of quantifying the effects of acid deposition on species richness after controlling for other important factors. A plot of the residuals from a standard multiple regression model against spatial location reveals a strong nonlinear relationship between species richness and lake location. With only one realization of the data, it is difficult, if not impossible, to tell whether this dependence should be modeled as deterministic spatial trend or as a spatial covariance structure. Two models are thus considered. The first is a multiple linear regression mod.
Polynomial stability without polynomial decay of the relaxation function

We consider a linear viscoelastic problem and prove polynomial asymptotic stability of the steady state. This work improves previous works where it is proved that polynomial decay of solutions to the equilibrium state occurs provided that the relaxation function itself is polynomially decaying to zero. In this paper we will not assume any decay rate of the relaxation function. In case the kernel has some flat zones then we prove polynomial decay of solutions provided that these flat zones are not too big. If the kernel is strictly decreasing then there is no need for this assumption. Copyright © 2008 John Wiley & Sons, Ltd.
Dynamic Problems of the Planets and Asteroids, and Their Discussion

The problems of dynamics of celestial bodies are considered which in the literature are explained by instability and randomness of movements. The dynamics of planets orbits on an interval 100 million years was investigated by new numerical method and its stability is established. The same method is used for computing movements of two asteroids Apophis and 1950DA. The evolution of their movement on an interval of 1000 is investigated. The moments of their closest passages at the Earth are defined. The different ways of transformation of asteroids trajectories into orbits of the Earth’s satellites are considered. The problems of interest are discussed from the different points of view.
The predictability of extratropical cyclones: Nonlinear sensitivity to localized potential‐vorticity perturbations

There is a range of phenomena which, if misrepresented in a numerical weather prediction model, could cause localized finite‐amplitude errors in the potential vorticity (PV). Examples are: convective systems, the tropopause PV trough, and orographic PV perturbations. Motivated by this, the sensitivity of short‐range cyclone forecasts (up to two days) to localized finite‐amplitude initial PV anomalies is investigated using a method termed ‘PV‐sensitivity mapping’. An initial PV‐anomaly perturbation is applied at each grid point in turn and the corresponding impact in a nonlinear cyclone development is computed. In contrast to the adjoint method, there is no linear approximation. The PV‐sensitivity map depicts the forecast time impacts (in energy and pressure) for each initial spatial location of PV perturbation. A nonlinear three‐dimensional quasi‐geostrophic model is used because it has PV as a prognostic variable, is numerically efficient, and simulates the essence of cyclogenesis.
An experimental study of the effect of external turbulence on the decay of a single vortex and a vortex pair

This study is concerned with the effect of external turbulence on the decay of vortices. Single vortices and vortex pairs were generated with wing(s) mounted in the sidewalls of a wind tunnel. The distance between the two vortices could be adjusted such that they just touched each other or overlapped. The intensity of the turbulence could be controlled with a turbulence grid. The development of the vortex was measured at a number of downstream stations with particle image velocimetry for a range of wing settings. The results indicate that the single vortex can be described by the ‘two length scales’ model of Jacquin, Fabre & Geffroy (AIAA, vol. 1038, 2001, p. 1). A vortex core, which decays like a Lamb–Oseen vortex, is embedded in a region with an almost constant radius and a much lower azimuthal velocity that obeys a ~r−β power law, with r being the radius measured from the vortex centre. For the turbulence levels and the test section length used in this study, the single-vortex behaviour is independent of the external turbulence and in contrast with the decay of the vortex pair that strongly depends on the external turbulence. In the initial stages of the vortex pair evolution, the vortices decay due to cancellation of vorticity at the symmetry plane. At a later stage, Crow oscillations are observed, followed by a breakdown of the vortices. This vortex breakdown might be due to direct turbulent action. The observed behaviour is in agreement with the theoretical model of Crow & Bate (J. Aircraft, vol. 13, 1976, p. 476).
Iterative projection algorithms in protein crystallography. I. Theory

A general class of iterative projection algorithms is described and proposed as a tool for phasing in protein crystallography in order to improve the radius of convergence over that of conventional density-modification algorithms. Their relationship to conventional density modification is described. The common iterative projection algorithms, their convergence properties and their application to protein crystallography are described. These algorithms offer the possibility of protein structure determination starting with only information on the molecular envelope and low-order non-crystallographic symmetry.
Parameterization of Atmospheric Radiative Transfer. Part I: Validity of Simple Models

Abstract This paper outlines a radiation parameterization method for deriving broadband fluxes that is currently being implemented in a number of global and regional atmospheric models. The rationale for the use of the 2-stream method as a way of solving the radiative transfer problem for broadband solar and longwave fluxes is presented. This rationale is based on assessment of these models in the context of a novel method of classifying radiative transfer problems that more clearly identifies the types of problems encountered in calculating globally distributed broadband fluxes. The delta-Eddington model (DEM) and the constant-hemispheric 2-stream models (CHMs) are shown to be superior to other 2-stream methods of solution under this classification and also superior to 4-stream solutions for the many classes of problems relevant to modeling the global atmosphere. These two methods are used to construct a radiation model of broadband solar and IR fluxes based on the k-distribution data of Fu and Liou. Whe.
On the boundary spectrum in banach algebras

We investigate some properties of the set S∂(a) = {λ ∈ ℂ: λ – a ∈ ∂S} (which we call the boundary spectrum of a) where ∂S denotes the topological boundary of the set S of all non-invertible elements of a Banach algebra A, and where a is an element of A.
THE DEGREE OF A QUASI-RULED MAPPING AND A NONLINEAR HILBERT PROBLEM

In this paper we present the theory of the degree of a mapping for a class, containing nonlinear (pseudo) differential operators, of nonlinear mappings in Banach spaces. This theory is applied to prove the existence of solutions to nonlinear boundary value problems in the theory of analytic functions, under some purely topological hypotheses. Bibliography: 11 items.
Quality Control of Accumulated Fields by Applying Spatial and Temporal Constraints

AbstractAccumulating gridded fields over time greatly magnifies the impact of impulse noise in the individual grids. A quality control method that takes advantage of spatial and temporal coherence can reduce the impact of such noise in accumulation grids. Such a method can be implemented using the image processing techniques of hysteresis and multiple hypothesis tracking (MHT). These steps are described in this paper, and the method is applied to simulated data to quantify the improvements and to explain the effect of various parameters. Finally, the quality control technique is applied to some illustrative real-world datasets.