Miracle-dz/UniFAR-FTUs huggingface dataset:
Nonlinear whistler instability driven by a beamlike distribution of resonant electrons

Theory and simulation are used to study the instability of a coherent whistler parallel-propagating in a simplified model radiation belt with a background of cold electrons, as well as a ring distribution of energetic electrons. A nonlinear instability is initiated at the location z+, where the electrons are cyclotron resonant with the wave, on the side of the equator (z=0) where the wave is propagating away from the equator. The instability propagates backward toward the equator, growing both spatially and temporally. As the instability develops, frequency falls in such a way as to keep the electrons nearly resonant with the waves over the entire region 0<z<z+. The instability causes a sharp drop in the pitch angle of the resonant electrons and eventually saturates with peak amplitude near the equator.
Ab initio modeling of molecular IR spectra of astrophysical interest: Application to CH4

Aims. We describe an ab initio-based numerical method of obtaining infrared spectroscopic data (line list) of polyatomic molecules that allows calculation of complete sets of lines for temperatures up to several thousand Kelvin. While the main focus is on completeness and consistency, not spectroscopic accuracy, the approach is in principle “exact” for line positions and, although not exact for line strengths, of sufficient accuracy to be of value, especially in wavelength regions where there are gaps in reliable experimental data. Methods. Global potential energy and dipole moment hypersurfaces are fitted to the results of ab initio electronic structure calculations. The MULTIMODE software is then used to obtain rovibrational energy levels and dipole transition matrix elements. This information is used to calculate a complete set of Einstein coefficients of spontaneous emission Aij. Results. The method is applied to obtain a spectroscopic database for methane containing over 1.4 million lines up to an upper state energy of 6200 cm −1 (∼9000 K). The emission spectrum of CH4 at 1000 K is calculated with the complete set of Einstein coefficients and compared with the one obtained from the HITRAN database. Gaps in the database are realistically filled in by the calculated spectrum. Conclusions. Consistent and complete databases are important for astrophysical applications. Databases obtained by the method described here fulfill this requirement and are sufficiently accurate for astrophysical applications such as model atmosphere calculations and the corresponding synthetic spectra.
Quality of functional capacity evaluation tests : a clinimetric approach

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The application of adaptive multichannel spectral estimation for broadband array processing

An alternative means of reducing the observation time required to make high-resolution broadband spatial spectral estimates is presented which precludes the need for preliminary periodogram cross spectral density matrix (CSDM) estimates. The methods described are based on low order multichannel minimum variance (MCMV), and multichannel autoregressive (MCAR) spectral estimators. The low-order nature of the array output process is shown by examining the approximate rank of a Hankel matrix defined from the array output assuming low order autoregressive moving average models of source spectra. Results based on simulation and actual towed array data which indicate MCMV and MCAR offer a means of observation time threshold reduction and comparable performance with previously proposed methods based on preliminary CSDM estimates are presented. <<ETX>>
Minimization of quadratic performance function in T-S fuzzy model

Describes the optimization of Takagi-Sugeno type fuzzy control. To prove the existence of optimal control, we applied compactness of a set of membership functions in L/sup /spl infin// space and continuity of inference process, and show the existence of a pair of membership functions, which minimize the quadratic performance function.
Structural Stability Tests with Unknown Breakpoint for the Efficient Method of Moments with Application to Stochastic Volatility Models

Tests for structural stability with unknown breakpoint are derived for and applied tothe efficient method of moments. Three types of tests are discerned: Wald type tests,Predictive tests and Hansen type tests. The Hansen type test for structural stabilitywith unknown breakpoint is a novelty for moment based techniques. Therefore for thistest asymptotic and local power results are provided. It turns out this test has thesame asymptotic distribution as the Hall and Sen test. All these tests are applied toan asymmetric stochastic volatility model for a series of daily observations of theS&P 500 index over the years 1963-1993. Our results indicate that the asymmetricstochastic volatility models fails all stability tests. The supremum type tests givean estimate of the breakpoint in first half of 1970. However the model seems to becomemore stable as time proceeds.
Focal shift in spatial-variant polarized vector Bessel–Gauss beams

The three dimensional intensity distribution of focused spatial-variant polarized vector Bessel–Gauss beams is investigated in the vicinity of the focal plane by using the Richards–Wolf vectorial diffraction method. The local polarized states of the incident beams vary between linearity and ellipse, and can be easily controlled in real time by a new parameter, namely the phase delay angle, which is introduced by a liquid crystal variable retarder. Our analysis proves the existence of a focal shift toward the focusing objective for this type of beam. The dependence of the focal shift on the different parameters of the beams is discussed in detail. Numerical results indicate that the magnitude of the focal shift is associated with the mode number, the local polarization, the beam width and the wavelength of the incident beams. The controllability of the focal shift indirectly caused by the phase delay angle will have great potential applications in optical micro-manipulation.
Magnetosphere‐ionosphere‐thermosphere coupling: Effect of neutral winds on energy transfer and field‐aligned current

The assimilative mapping of ionospheric electrodynamics (AMIE) algorithm has been applied to derive the realistic time-dependent large-scale global distributions of the ionospheric convection and particle precipitation during a recent Geospace Environment Modeling (GEM) campaign period: March 28-29, 1992. The AMIE outputs are then used as the inputs of the National Center for Atmospheric Research thermosphere-ionosphere general circulation model to estimate the electrodynamic quantities in the ionosphere and thermosphere. It is found that the magnetospheric electromagnetic energy dissipated in the high-latitude ionosphere is mainly converted into Joule heating, with only a small fraction (6%) going to acceleration of thermospheric neutral winds. Our study also reveals that the thermospheric winds can have significant influence on the ionospheric electrodynamics. On the average for these 2 days, the neutral winds have approximately a 28% negative effect on Joule heating and approximately a 27% negative effect on field-aligned currents. The field-aligned currents driven by the neutral wind flow in the opposite direction to those driven by the plasma convection. On the average, the global electromagnetic energy input is about 4 times larger than the particle energy input.
Local boundary value problems for the error in FE approximation of non‐linear diffusion systems

In this work we investigate the a posteriori error estimation for a class of non‐linear, multicomponent diffusion operators, which includes the Stefan–Maxwell equations. The local error indicators for the global error are based on local boundary value problems, which are chosen to approximate either the global residual of the finite element approximation or the global linearized error equation. Using representative numerical examples, it is shown that the error indicators based on the latter approach are more accurate for estimating the global error for this problem class as the problem becomes more non‐linear, and can even produce better adaptive mesh refinement (AMR). In addition, we propose a new local error indicator for the error in output functionals that is accurate, inexpensive to compute, and is suitable for AMR, as demonstrated by numerical examples. Copyright © 2007 John Wiley & Sons, Ltd.
The Integral Closure of Modules, Buchsbaum–Rim Multiplicities and Newton Polyhedra

The integral closure and the Buchsbaum‐Rim multiplicity are computed of a wide class of submodules of Onp through suitable Newton polyhedra. The result thus obtained is an extension to submodules of Onp of the works of Yoshinaga and Saia on the characterization of Newton non‐degenerate functions and ideals, respectively.
Measurements of the Total Water Content of Cirrus Clouds. Part II: Instrument Performance and Validation

Abstract This paper describes the performance and in-flight validation of an instrument mounted in a pallet on the NASA WB-57 research aircraft that measures the sum of gas phase and solid phase water, or total water, in cirrus clouds. Using a heated isokinetic inlet and a Lyman-α photofragment fluorescence technique for detection, measurements of total water have been made over three orders of magnitude. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL FACE), the instrument operated at duct temperatures sufficiently warms to completely evaporate particles up to 150-μm diameter. Laboratory calibrations, in-flight diagnostics, intercomparison with water vapor measured by absorption in flight, and intercomparisons in clear air with the Harvard water vapor instrument validate the detection sensitivity of the instrument and illustrate the minimal hysteresis from instrument surface contamination. The Harvard total water and water vapor instruments to.
Polynomial convexity and totally real manifolds

In this article we study generic properties of totally real submanifolds M of . On the one hand we show that if M is polynomially convex and also has bounded exhaustion hulls, then sufficiently small -perturbations of M are polynomially convex and have bounded exhaustion hulls. The proof of this relies on an explicit local function (the Gaussian kernel) and the solution of a Cousin I problem. On the other hand, if , there exist arbitrarily small -perturbations M′ of M such that M′ is polynomially convex and has bounded exhaustion hulls. The proof is a further development of an idea of Forstnerič and Rosay to push different pieces of M into different complex submanifolds of . We also give a perturbation result that can be obtained by applying a holomorphic automorphism.
N ov 2 01 4 Nearly Kähler submanifolds of a space form Nikrooz Heidari

In this article we study isometric immersions of nearly Kähler manifolds into a space form (specially Euclidean space) and show that every nearly Kähler submanifold of a space form has an umbilic foliation whose leafs are 6-dimensional nearly Kähler manifolds. Moreover using this foliation we show that there is no non-homogeneous 6-dimensional nearly Kähler submanifold of a space form. We prove some results towards a classification of nearly Kähler hypersurfaces in standard space forms.
Analysis and Cost Optimization of the M/G/1 Queue Under the D-Policy and LCFS Discipline

Abstract We deal with the M/G/1 queues under the D-policy and last-come-first-served (LCFS) disciplines. We first derive the queue length and waiting time distributions in the form of probability generating functions and the Laplace–Stieltjes transforms. Then we derive the mean performance measures. Finally, we obtain the optimal values of D under a linear cost function.
Some Empirical Distributions of Bivariate T 2 and Homoscedasticity Criterion M Under Unequal Variance and Leptokurtosis

Abstract Computer generated pseudo random numbers were used to simulate drawing 1000 pairs of samples of N 1, N 2 = 5, 10, 20 from bivariate populations normal (O, σ i 2 I) having σ2/σ1 = 1, 1.6 or 3.2, and from circular bivariate symmetrical leptokurtic populations with zero means, equal variances and β2 − 3 = 3.2 or 6.2. Results suggest that the null distribution of T 2 for pairs of bivariate normal samples with N 1 = N 2 ≥ 10 is rather robust against variance inequality but that this robustness does not extend to disparate sample sizes, and that upper tail frequencies of the distribution of bivariate T 2 for N 1, N 2 ≥ 10 are not substantially affected by moderate degrees of symmetrical leptokurtosis. In simulations of sampling from circular normal populations with scale parameters in the ratio of 1.6:1 and 3.2:1 respectively, the proportion of M exceeding the null 5% point ranged from 9% and 49% for N 1 = N 2 = 5 to 60% and 100% for N 1 = N 2 = 20. In simulations of homoscedastic leptokurtic sampling,.
Generalization of the Stolper-Samuelson Theorem

This paper is concerned with the generalization of the Stolper-Samuelson theorem from the 2 x 2 case to the n x n case. We start by proving theorems establishing the validity of the factor price equalization theorem and the Stolper-Samuelson theorem for the n x n case. The conditions established in these theorems are then interpreted economically in terms of the generalized versions of factor intensity. It may be noted that the above results, apart from being more readily interpretable in economic terms, are of basic mathematical interest.
Improvement of a technique for localization of steel needles in humans using a SQUID magnetometer

A technique was previously developed, based on magnetic field measurements, to localize hypodermic and sewing needles lost in the human body, with the purpose of surgical extraction. The measurements are performed using a SQUID magnetometer, which detects the magnetic field associated with the remanent magnetization of the needle. The technique allowed easy surgical localization of the needles with good precision in all six clinical cases studied so far. The procedure greatly decreases the surgery time for foreign body extraction, and also reduces the generally high odds of failure. This paper presents an improvement of the original algorithm, which is now independent of any constant magnetic field component, thus overcoming the main experimental difficulty usually found, namely that a SQUID system does not measure absolute fields.
Rapidly rotating α2-dynamo models

We present numerical calculations for a special α2-dynamo basing on an α-tensor proportional to (δim + α3ωiωm/ω2). (gω). For α3 = – 1 this non-linear expression reflects the inducting action of (weakly) inhomogeneous stochastic motions for very rapid rotation, ω > ωc. As far as the natural cosmic objects are concerned we do not know, however, the frequency ωc of the fluctuating mide with which the rotational rate Ω has to be compared. The calculations provide the non-axisymmetric but equatorially symmetric magnetic S1-mode to be a preferred one, the poloidal part of which is similar to a dipolar system lying in the equator plane. For α3 = o … – 1 its eigenvalue remains nearly unchanged whereas the eigenvalues of the other modes strongly increase. In the case of very rapid rotation, finally, this mode possesses the lowest eigenvalue. Therefore, the generation of global magnetic fields by the α-effect is not substantially obstructed by fast rotation. The realized magnetic rotator should be expected to be a non-axisymmetric but equatorially symmetric one, which sems to correspond with the observations. From the discussion of the time-related eigenvalue we obtain the information that the longitudinal drifting of the nonaxisymmetric fields has always a westward direction. Es werden die Ergebnisse numerischer Untersuchungen von α2-Dynamo-Modellen vorgestellt, welche sich auf einen α-Tensor der Gestalt (δim + α3ΩiΩm/Ω2). (gΩ) beziehen. Dieser Tensor liefert fur α3 = – 1 den fur sehr schnelle Rotation, ω >c, gultigen Ausdruck, wobei wir aber die zum Vergleich heranzuziehenden Frequenzen ωc der α-aktiven Turbulenz fur die einzelen Himmelskorper nicht kennen. Unsere Ergebnisse weisen der nichtaxial-aber aquatorsymmetrischen S1-Mode, fur die ein in der Aquatorebene liegender magnetischer Dipol ein Beispiel darstellt, eine besondere Bedeutung zu, weil sich der zugehorige Eigenwert fur α3 = o … – 1 kaum andert, wahrend die Eigenwerte der anderen Doden stark anwachsen. Bei Einbeziehung der (auch beobachteten) nichtaxialsymmetrischen Moden findet man daher keine bedeutsamen Unterschiede in der Fahigkeit zur Dynamoerregung zwischen langsam und schnell rotierenden Sternen. Bemerkenswerterweise zeigen alle untersuchten nichtaxialsymmetrischen Magnetfelder ein westwarts gerichtete Driftbewegung.
Comparison between two finite‐difference schemes for computing the flow around a cylinder

Separated flow past a circular cylinder is computed from two finite-difference Navier–Stokes models. Stream functions are calculated using a successive-over-relaxation (SOR) procedure. Alternating-direction-implicil (ADI) and ‘upwind’ directional difference explicit (DDE) numerical schemes for solving the vorticity-transport equation are compared. The ‘upwind’ differencing technique produces artificial viscosity which damps the wake and suppresses vortex shedding. It is shown to be unreliable and so the ADI approach is recommended.
Integral equation analysis of electromagnetic wave propagation in periodic structure and error analysis of various basis functions in projection of plane waves

In the first part of this dissertation, the integral equation approaches are developed to analyze the wave propagation in periodic structures. Firstly, an integral equation approach is developed to analyze the two-dimensional (2-D) scattering from multilayered periodic array. The proposed approach is capable of handling scattering from the array filled with different media in different layers. Combining the equivalence principle algorithm and connection scheme (EPACS), it can be avoided to find and evaluate the multilayered periodic Green’s functions. For 2N identical layers, the elimination of the unknowns between top and bottom surfaces can be accelerated using the logarithm algorithm. More importantly, based on EPACS, an approach is proposed to effectively handle the semi-infinitely layered case in which a unit consisting of several layers is repeated infinitely in one direction. Secondly, the integral-equation (IE) method formulated in the spatial domain is employed to calculate the scattering from the doubly periodic array of three-dimensional (3-D) perfect electric conductor (PEC) objects. The special testing and basis functions are proposed to handle the problem with non-zero normal components of currents at the boundary of one period. Moreover, a relationship between the scattering from the PEC screen and its complementary structure is established. In order to efficiently compute the matrix elements from the IE approach, an acceleration technique with the exponential convergence rate is applied to evaluate the doubly periodic Green’s function. The formulations in this technique are appropriately modified so that the new form facilitates numerical calculation for the general cases. In the second part of this dissertation, the error analysis of various basis functions in projection of the plane wave was conducted, including pulse basis, triangular basis, the basis of their higher-order version, and the divergence-conforming basis on rectangular and triangular elements. The projection error is given analytical, asymptotically, and numerically. The application of the p-th order one-dimensional
Gravitational collapse and weak interactions

The behavior of a massive star during its final catastrophic stages of evolution has been investigated theoretically, with particular emphasis upon the effect of electron-type neutrino interactions. The methods of numerical hydrodynamics, with coupled energy transfer in the diffusion approximation, were used. In this respect, this investigation differs from the work of Colgate and White (1964) in which a "neutrino deposition" approximation procedure was used. Gravitational collapse initiated by electron capture and by thermal disintegration of nuclei in the stellar center is examined, and the subsequent behavior does not depend sensitively upon which process causes the collapse.As the density and temperature of the collapsing stellar core increase, the material becomes opaque to electron-type neutrinos and energy is transferred by these neutrinos to regions of the star less tightly bound by gravity. Ejection of the outer layers of the star can result. This phenomenon has been identified with supernovae.Un.
Theory of edge diffraction in terms of dynamic ray tracing

SUMMARY If a sharp edge occurs in a reflector, the wavefield predicted by geometric ray theory shows shadow boundaries between illuminated zones and shadow zones. One may correct for these discontinuities in the wavefield by adding edge waves as introduced by Klem-Musatov. In this paper the edge wave is analysed as a solution of a parabolic differential equation that describes transverse diffusion between the illuminated zone and the shadow zone across the shadow boundary. Here, the edge wave is described constructively in terms of dynamic ray tracing, thereby indicating how it can be implemented in a ray tracing program when the latter is equipped with the facility of dynamic ray tracing.
A High-Resolution Numerical Simulation of the Wind Flow in the Ross Island Region, Antarctica

Abstract A detailed description of the characteristics of the three-dimensional wind flow for the Ross Island region of Antarctica is presented. This region of Antarctica has complex topographic features, and the wind flow is dependent on the topography and the local meteorological conditions. High-resolution nonhydrostatic numerical simulations are conducted over a high-resolution domain in the Ross Island region. Two simulations are performed corresponding to the two dominant wind flow patterns in the Ross Island region. The first simulation is a light wind case with a stable lower atmosphere and the second is a high wind speed event. Froude number calculations, along with a study of the equation of motion, are included for a more complete understanding of the dynamics of the wind flow. The results of the simulations show a favorable correlation to past research results and observations, and provide a more complete understanding of the three-dimensional wind flow in the region. In addition to a more tho.
Grid turbulence at large Reynolds numbers

Measurements of grid turbulence have been obtained for grid Reynolds numbers ranging from 2·4 × 106 to 1·2 × 105. The decay law and the effect of Reynolds number on the turbulence level are established. The measured power spectra of the turbulence are consistent with Kolmogoroff scaling for kη > 0·1 (k is the wave-number and η is the Kolmogoroff length); but for kη < 0·1, the spectra of the stream-wise turbulence velocity component and of the cross-stream component do not appear to be isotropically related. However, the stream-wise spectrum does display a $-\frac{5}{3}$ region, which increases in extent with increasing Reynolds number.