Miracle-dz/UniFAR-FTUs huggingface dataset:
Piecewise uniform bases and energetic approach for discrete constitutive matrices in electromagnetic problems

In the paper we introduce piecewise uniform edge and face vector functions on a simplicial primal cell complex having geometric structure common to Whitney's vector functions. We also introduce piecewise uniform bases functions in the barycentric dual complex, where the analogous of Whitney's functions does not exist. By using these piecewise uniform bases functions and by exploiting an energetic approach, we construct symmetric positive definite constitutive matrices for discrete Maxwell's equations. We also prove that these constitutive matrices are deeply related to those of the finite elements with Whitney's bases functions. Copyright © 2005 John Wiley & Sons, Ltd.
Shock-excited NH3 (3, 3) masers in the NGC 6334 star-forming region

We report the discovery of four NH3 (3, 3) masers in the NGC 6334 star formation region. The masers are found in two of the seven far-infrared continuum sources where high-mass star formation is taking place in this molecular cloud. These masers occur at the ends of high-velocity molecular outflows; no maser emission was found near regions without high-velocity outflows. The NH3 masers are not associated with any other type of maser. These results confirm that the NH3 (3, 3) masers are caused by shocks and probably mark the location where the molecular outflow jet impinges upon the ambient medium.
Determining the electron temperature in inductively coupled nitrogen plasmas by optical emission spectroscopy with molecular kinetic effects

An improved method to determine electron temperature in inductively coupled nitrogen plasmas using optical emission spectroscopy is proposed. The molecular kinetic model, which includes the kinetic rates of excited nitrogen molecules, evaluates the line ratio by including all emission lines in the first and second positive band system of molecular nitrogen. The calculated electron temperature is compared with measured values by a Langmuir probe in the discharge pressure range between 1 and 10 mTorr.
Dynamical aspects of the October storm, 1987: a study of a successful fine-mesh simulation

A diagnostic study of a successful numerical simulation of the October storm 1987 is described. This good, non-operational forecast was obtained using the Meteorological Office's fine-mesh model run from a revised analysis at 00 GMT on 15 October 1987. the Meteorological Office's mesoscale model was also run using initial conditions at 12 GMT 15 October obtained by interpolating the above fine-mesh forecast fields to examine the benefits of very high horizontal resolution (15km grid length). Diagnostic maps and cross-sections derived are used to address two scientific issues: (i) the role of weak moist slantwise stability (or, alternatively, positive slantwise convective potential energy) (ii) the dynamical significance of the striking cloud structure (the cloud head) seen in the satellite imagery early in the storm's life. It appears that the baroclinic zone, in which the storm develops, is highly receptive to forcing by an upper trough and the warm boundary-layer air just ahead of the main surface front is characterized by substantial slantwise convective available energy. the cloud head is identified with a region of intense slantwise ascent in the warm air just above the main frontal zone. Its great meridional extent is associated with the upper tropospheric outflow and horizontal spreading of air which has recently undergone rapid slantwise ascent. the low-level temperature field exhibits, throughout the development period, a remarkable shape-preserving thermal ridge of considerable intensity. the sensitivity of the forecast to the removal of surface energy fluxes and latent heat of condensation are investigated separately. It is found that on the timescale of the simulation, surface energy fluxes have negligible impact on the explosive development. On the other hand, the contribution of latent-heat release to the development appears to dominate the dry baroclinic instability process.
Time domain structures: What and where they are, what they do, and how they are made

Time domain structures (TDS) (electrostatic or electromagnetic electron holes, solitary waves, double layers, etc.) are ≥1 ms pulses having significant parallel (to the background magnetic field) electric fields. They are abundant through space and occur in packets of hundreds in the outer Van Allen radiation belts where they produce magnetic‐field‐aligned electron pitch angle distributions at energies up to a hundred keV. TDS can provide the seed electrons that are later accelerated to relativistic energies by whistlers and they also produce field‐aligned electrons that may be responsible for some types of auroras. These field‐aligned electron distributions result from at least three processes. The first process is parallel acceleration by Landau trapping in the TDS parallel electric field. The second process is Fermi acceleration due to reflection of electrons by the TDS. The third process is an effective and rapid pitch angle scattering resulting from electron interactions with the perpendicular and parallel electric and magnetic fields of many TDS. TDS are created by current‐driven and beam‐related instabilities and by whistler‐related processes such as parametric decay of whistlers and nonlinear evolution from oblique whistlers. New results on the temporal relationship of TDS and particle injections, types of field‐aligned electron pitch angle distributions produced by TDS, the mechanisms for generation of field‐aligned distributions by TDS, the maximum energies of field‐aligned electrons created by TDS in the absence of whistler mode waves, TDS generation by oblique whistlers and three‐wave‐parametric decay, and the correlation between TDS and auroral particle precipitation, are presented.
Linear differential equation with additional conditions and formulae for green's function

In this paper, we investigate the m-order linear ordinary differential equation with m linearly independent additional conditions. We have found the solution to this problem and give the formula and the existence condition of Green's function. We compare two Green's functions for two such problems with different additional conditions and apply these results to the problems with nonlocal boundary conditions.
Slumping of Si wafers at high temperature

Space X-ray imaging telescopes have delivered unique observations that have been significantly contributing to many important discoveries of current astrophysics. For future telescopes with a larger collecting area and a better angular resolution, the limiting factor is their X-ray reflecting mirror array. Therefore, for a successful construction of future lightweight and highly reflecting X-ray mirrors, new cost-effective technologies and progressive materials are needed. Currently, the very promising materials are silicon foils which are commercially produced on a large scale. We focused on the plastic deformation of thin monocrystalline silicon foils, which was necessary for the precise thermal forming of the foils to 3D shapes. To achieve the plastic deformation, we applied forced slumping at temperatures from 1200 to 1400°C. The final shapes and the surface quality of the foils were measured using a Taylor Hobson contact profilometer and examined with an Atomic Forced Microscopy. We studied the effects of temperature, applied slumping force, heattreatment time, crystal orientation, and furnace atmosphere on the shape and surface quality of the formed foils.
CONTINUOUS AND DISCONTINUOUS LINEAR APPROXIMATION OF THE WINDOW SPECTRUM BY LEAST SQUARES METHOD

This paper presents the general solution of the least-squares approximation of the frequency characteristic o f the data window by linear functions combined with zero padding technique. The approx imation characteristic can be discontinuous or continuous, what depends on the value of one approximation parameter. The approximation solution has an analytical form and therefore the resul ts have universal character. The paper presents derived formulas, analysis of approximation accuracy, the exemp lary characteristics and conclusions, which confirm high accuracy of the approximation. The presented solut ion is applicable to estimating methods, like the LIDFT method, visualizations, etc.
Radiation forces on a microsphere in an arbitrary refractive index profile

The force equations describing the radiation forces on a microsphere in an arbitrary refractive index profile are derived here by using the photon-stream method in a ray-optics regime. A loosely focused Gaussian beam was employed as the radiating illumination beam. The radiation forces on a spherical microsphere were calculated in a time-varying refractive index profile. The refractive index profile of the surrounding medium was evaluated according to the concentration distribution obtained from the diffusion equation. The scattering and gradient forces on a microsphere were calculated for different refractive indices (1.22, 1.33, 1.43, and 1.59), and the radiation forces on a perfectly reflecting microsphere were calculated. The results were compared with previous results to validate the derivation.
The Effect of the Number of Observations per Parameter in Misspecified Confirmatory Factor Analytic Models

Abstract Some authors have suggested that sample size in covariance structure modeling should be considered in the context of how many parameters are to be estimated (e.g., Kline, 2005). Previous research has examined the effect of varying sample size relative to the number of parameters being estimated (N:q). Although some support has been found for this effect, the effect size appears to be small compared to other influences, such as indicator reliability and sample size (Jackson, 2003). Efforts to extend this work to the case where models are intentionally misspecified are described in this article. In addition to varying the number of observations per estimated parameter, several other known influences on model fit were varied such as sample size, the degree of misspecification, number of variables per factor, and the communality of the measured variables. The results suggest that decreasing the number of parameters to be estimated while holding sample size constant can help detect misspecification errors, and some fit indexes were more sensitive to this manipulation than others. In general, the effects of N:q were small relative to other experimental effects.
Supervision of Infinite Behavior of Discrete-Event Systems

Some basic results of supervisory control theory are extended to the setting of $\omega$-languages, formal languages consisting of infinite strings. The extension permits the investigation of both liveness and safety issues in the control of discrete-event systems. A new controllability property appropriate to the infinitary setting ($\omega$-controllability) is defined; this language property captures in a natural way the limitations of available control actions. It is shown that every specification language contains a unique maximal $\omega$-controllable sublanguage, representing the least upper bound of the set of achievable closed-loop sublanguages. This supremal $\omega$-controllable sublanguage allows a simple formulation of necessary and sufficient conditions for the solvability of an infinitary supervisory control problem. The problems of effectively deciding solvability of the control problem and of effectively synthesizing appropriate supervisors are solved for the case where the plant is represented by a deterministic Buchi automaton and the specification of legal behavior by a deterministic Rabin automaton.
Some properties of 2-critically finite holomorphic maps of ${\bf P}^2$

We define 2-critically finite maps of ${\bf P}^2$ and show that they have no nontrivial closed backward invariant sets. In particular, their Julia sets $J_1$, defined as the support of a natural invariant measure, are equal to ${\bf P}^2$. We also prove that repelling periodic points are dense for such maps.
Surfactant Effects on Bubble Motion and Bubbly Flows

Small amounts of surfactant can drastically change bubble behavior. For example, a bubble in aqueous surfactant solution rises much slower than one in purified water. This phenomenon is explained by the so-called Marangoni effect caused by a nonuniform concentration distribution of surfactant along the bubble surface. In other words, a tangential shear stress appears on the bubble surface due to the surface tension variation caused by the surface concentration distribution, which results in the reduction of the rising velocity of the bubble. More interestingly, this Marangoni effect influences not only the rising velocity, but also the lateral migration in the presence of mean shear. Furthermore, these phenomena influence the multiscale nature of bubbly flows and cause a drastic change in the bubbly flow structure. In this article, we review the recent studies related to these interesting behaviors of bubbles caused by the surfactant adsorption/desorption on the bubble surface.
Stability conditions for polytopes of polynomials

The stability of linear systems with uncertain parameters is addressed. The author treats the mathematical problem of deciding whether or not all polynomials in some specified family are Omega -stable (have all their zeros in the subset Omega of the complex plane). For a general stability region in the complex plane, a stability criterion for polytopes of polynomials is given in terms of the stability of a minimal number of corners and edges of the polytope. The 'testing set' of edges and corners depends entirely on the edge directions of the polytope, hence the results are particularly applicable when the directions are fixed, but the lengths and positions of the edges are allowed to vary. Applications to robust pole placement of uncertain systems and computation of worst case H infinity norms are demonstrated. <<ETX>>
Extension of PIV for measuring granular temperature field in dense fluidized beds

In this work a particle image velocimetry (PIV) technique has been extended to enable the simultaneous measurement of the instantaneous velocity and granular temperature fields. The PIV algorithm has been specifically optimized for dense granular systems and has been thoroughly tested with artificially generated images. The new PIV technique has been successfully applied to a fluidized bed at incipient fluidization conditions in which a single bubble is injected by a jet and to a freely bubbling fluidized bed. The instantaneous spatial distribution of the solids-phase velocity and granular temperature that can be measured with this new technique can be used to validate CFD models for dense granular systems, such as multifluid continuum models using the KTGF (kinetic theory of granular flow) to describe the internal momentum transport in the particulate phase
Stabilizing Gain Regions of PID Controller for Time Delay Systems

Based on the inverse Nyquist plot, this paper proposes a method to determine stabilizing gain regions of PID controller for time delay systems. According to the frequency characteristic of the inverse Nyquist plot, it is confirmed that the frequency range is used for stability analysis, and the abscissas of two kind key points are obtained in this range. PID gain is divided into several regions by abscissas of key points. Using an inference and two theorems presented in the paper, the stabilizing PID gain regions are determined by the number of intersections of the inverse Nyquist plot and the vertical line in the frequency range. This method is simple and convenient. It can solve the problem of getting the stabilizing gain regions of PID controller for time delay system.
The Kepler conjecture

This is the eighth and final paper in a series giving a proof of the Kepler conjecture, which asserts that the density of a packing of congruent spheres in three dimensions is never greater than $\pi/\sqrt{18}\approx 0.74048. $. This is the oldest problem in discrete geometry and is an important part of Hilbert's 18th problem. An example of a packing achieving this density is the face-centered cubic packing. This paper completes the fourth step of the program outlined in math.MG/9811073: A proof that if some standard region has more than four sides, then the star scores less than $8 \pt$.
Friction Drag Reduction of External Flows with Bubble and Gas Injection

The lubrication of external liquid flow with a bubbly mixture or gas layer has been the goal of engineers for many years, and this article presents the underlying principles and recent advances of this technology. It reviews the use of partial and supercavities for drag reduction of axisymmetric objects moving within a liquid. Partial cavity flows can also be used to reduce the friction drag on the nominally two-dimensional portions of a horizontal surface, and the basic flow features of two-dimensional cavities are presented. Injection of gas can lead to the creation of a bubbly mixture near the flow surface that can significantly modify the flow within the turbulent boundary layer, and there have been significant advances in the understanding of the underlying physical process of drag reduction. Moreover, with sufficient gas flux, the bubbles flowing beneath a solid surface can coalesce to form a thin drag-reducing air layer. The current applications of these techniques to underwater vehicles and surface ships are discussed.
Automated Weight Windows for Global Monte Carlo Particle Transport Calculations

Abstract A new method for efficiently solving global Monte Carlo particle transport problems is presented. (In these problems, flux information is desired across the entire system, not just at a small number of detector locations.) The method is based on the use of a weight window that distributes Monte Carlo particles uniformly throughout the system. This (a) ensures that all subregions of the system are adequately sampled and (b) controls the particle weights, even in subregions far from sources. The weight window is constructed from an approximate deterministic solution of the forward transport problem. It is argued that a weight window based on the forward transport solution is more appropriate for global problems than the more familiar concept of basing a weight window on an adjoint solution for source-detector problems. It is also shown that by using Monte Carlo–generated Eddington factors in deterministic solutions of the quasi-diffusion equation, one can inexpensively compute updated forward-based weight windows and obtain a more efficient global Monte Carlo calculation.
Detecting corrosion using thermal measurements

This paper deals with the inverse problem of detecting the level of corrosion at the interface of an inclusion given thermal measurements at the accessible boundary of the sample. This leads to a transmission problem for the heat equation with an unknown coefficient in a transmission condition. We consider both time-harmonic and delta-pulse excitations. In both cases we prove uniqueness results for the inverse problem. To reconstruct the unknown level of corrosion numerically, we study a non-iterative method and a regularized Newton method and compare their performances in a number of numerical experiments.
A Sun in the Spectroscopic Binary IM Pegasi, the Guide Star for the Gravity Probe B Mission

We present the first detection of the secondary of the spectroscopic binary system IM Pegasi (HR 8703), the guide star for the NASA-Stanford relativity gyroscope mission Gravity Probe B. In support of this mission, high-resolution echelle spectra of IM Peg have been obtained on an almost nightly basis. Applying the technique of least-squares deconvolution, we achieve very high signal-to-noise ratio line profiles and detect the orbit of the secondary of the system. Combining almost 700 new radial velocity measurements of both the primary and secondary of the system with previous measurements, we derive improved orbital parameters of the IM Peg system. Using these estimates along with the previously determined range of orbital inclination angles for the system, we find that the primary of IM Peg is a giant of mass 1.8 ± 0.2 M☉, while the secondary is a dwarf of mass 1.0 ± 0.1 M☉.
A Second-order Gradient Method for Determining Optimal Trajectories of Non-linear Discrete-time Systems

ABSTRACT A second-order method of successively improving a control sequence for a non-linear discrete-time system is derived. One step convergence is obtained for linear systems with quadratic performance functions. Although the results are of interest in their own right, a second-order method for continuous-time systems is obtained by formally allowing the sampling interval to approach zero. The equations so obtained differ slightly, because of the method of derivation, from results already obtained using the calculus of variations approach. The difference, which is an advantage of the method described in this paper, is that one vector differential equation less has to be integrated. The approach used in the derivation is motivated by dynamic programming and facilitates the application of gradient methods to stochastic problems which will be the subject of a future paper.
Borel cocycles, approximation properties and relative property T

Let $G$ and $H$ be locally compact groups. Assume that $G$ acts on a standard probability space $(S,\mu)$, $\mu$ being $G$-invariant. We prove that if there exists a Borel cocycle $\alpha:S\times G\longrightarrow H$ which is proper in an appropriate sense, then $G$ inherits some approximation properties of $H$, for instance amenability or the so-called Haagerup Approximation Property. On the other hand, if $G_{0}$ is a closed subgroup of $G$, if the pair $(G,G_{0})$ has the relative property (T) of Margulis [19] and if either $H$ has Haagerup Approximation Property, or if it is the unitary group of a finite von Neumann algebra with a similar property, then we give rigidity results analogous to that in [23] and [1].
High angular resolution submillimeter observations of Sagittarius B2

Continuum observations of the Sgr B2 molecular cloud have been carried out. The data offer the first detailed description of the submillimeter radiation from this complex source. The emission is dominated by the middle and northern compact sources, but the far-infrared radiation associated with the Northeast H II region L and from the southern H II region/molecular maser source H have been detected for the first time. The data, together with existing infrared measurements, indicate that the optical depth within Sgr B2(N) is significantly greater than that of Sgr B2(M) and that it has a noticeable effect for lambda = 800 microns or less. The envelope of Sgr B2(M) becomes optically thick for the radiation from Sgr B2(N), located within it, for wavelengths 100 microns or less. From radiative transfer modeling, a luminosity of 10 million solar is obtained for the middle source and 2 million solar for the northern source. 30 refs.
Study at high frequencies of a stratified waveguide

A waveguide in integrated optics is defined by its refractive index. The guide is assumed to be invariant in the propagation direction while in the transverse direction it is supposed to be a compact perturbation of an unbounded stratified medium. We are interested in the high frequency modes guided by this device. We consider the problem under the assumptions of weak guidance, so that it reduces to a two-dimensional eigenvalue problem for a scalar field. While a general study has been done in a previous paper (Bonnet-BenDhia et al., IMAJAM 60, 1998), our goal here is to present an asymptotic study at high frequencies, which illustrates the dispersive character of the stratified guide. We will give the limit as the frequency tends to ∞ of the guided modes and characterize this limit as the solution of an eigenproblem. The technical difficulty lies in the stratified character of the unbounded reference medium.