Miracle-dz/UniFAR-FTUs huggingface dataset:
Volume‐tracking of subgrid particles

A new PLIC‐VOF method is proposed to track deformable particles, such as bubbles and liquid droplets, that can be smaller than the grid spacing. The idea is to replace the surface normal (SN) calculation used in the PLIC, by the SN vector obtained from partial differential equations that are solved together with the advection algorithm. The equations for the evolution of SN vector are derived, and examined by using the first‐order and the second‐order upwind schemes. Since the normal vector is defined in every cell, the method generally improves the accuracy at low grid resolution. It is found that a normal vector of zero magnitude is located at the centroid of a particle, to second‐order accuracy for small particles. The motion of a subgrid particle is controlled by the arrival of the zero vector in the present PLIC/SN method, so that the particle can be translated at the right speed without any additional treatment. This has been numerically verified by simulating a particle of one‐tenth of grid spacing traveling in three different directions, in addition to a few typical test cases. Copyright © 2010 John Wiley & Sons, Ltd.
Aircraft flight controller tracking design using H-Infinity static output-feedback

This paper presents an approach for designing compensators of specified structure for shaping the closed-loop step response that uses H-Infinity output-feedback design techniques. This approach results in controllers that take advantage of the wealth of experience in aircraft control design. Simplified conditions are presented, which only require the solution of two coupled matrix design equations. A new numerically efficient algorithm to solve the H-Infinity disturbance attenuation is given. An F-16 normal acceleration design example is solved to illustrate the power of the proposed approach.
Multi-parameter Tikhonov regularization with the ℓ0 sparsity constraint

Using a sparsity promoting penalty term in the Tikhonov regularization scheme has been shown to be efficient in reconstructing solutions which own a sparse structure. These penalty terms usually take the form of ℓp (quasi-)norm with p ∈ (0, 2). At the same time, some examples have been shown where there is no regularizing property for the extreme penalty term with p = 0. Here, we examine the multi-parameter Tikhonov regularization with both ℓ0 and ℓ2 penalty terms for nonlinear ill-posed problems. We will show, in the following, that the proposed multi-parameter Tikhonov functional has a minimizer as well as the convergence result when the noise level tends to 0. Error estimates for the discrepancy principle are verified under appropriate source conditions and nonlinearity assumptions. Finally, two numerical examples shed light on the appropriateness of the proposed method.
Kinetic equations for plasmas subjected to a strong time-dependent external field. Part 1. General theory

It is shown that the concept of subdynamics introduced by Prigogine, George & Henin, and extended by Balescu & Wallenborn, can be generalized nontrivially to systems submitted to time-dependent external fields. The distribution vector of the system is split into two components by means of a time- dependent projection operator. Each of these obeys an independent equation of evolution. The description of the evolution of one of these components (the superkinetic component) can be reduced to a kinetic equation for a one-particle distribution function. It is shown that, when the external field vanishes for all times t ≤ t0, and if the system has reached a (field-free) equilibrium (or a ‘kinetic state’) at time t0, then for t ≥ t0 the kinetic equation derived here provides an exact and complete description of the evolution. A general expression for the nonlinear response of the system to the external field is derived.
545 Convection in Lorenz ’ s global energy cycle with the ECMWF model

Lorenz’s global energy cycle includes the conversion rate C between available potential and kinetic energy. In traditional estimates of C only gridscale processes were evaluated; sub-gridscale processes were lumped into dissipation. It is argued that this is inadequate; organized sub-gridscale heat fluxes like deep convection cannot be treated as molecular. Here both Cgrid and Csub are evaluated from the ECMWF Integrated Forecast System (IFS), for a one year forecast in climate mode. The sub-gridscale fluxes are obtained from the model parametrization and the results tested for consistency; the largest contribution comes from the convection scheme. The integrand of Csub, the familiar buoyancy flux −α ′ω ′, is locally much smaller than its gridscale counterpart −α ω. However, the buoyancy flux is upward throughout, and thus representative for, the global atmosphere. The global annual means are Cgrid=(3.4±0.1)W/m2 and Csub=(1.7±0.1)W/m2. Further, the gridscale generation rate of available potential energy is evaluated independently and found to be Ggrid=(3.0±0.2)W/m2. These results suggest that (i) the sub-gridscale processes contribute significantly to the Lorenz energy cycle, and (ii) the cycle, represented by the total dissipation of D=(5.1±0.2)W/m2, is more intense than all earlier gridscale estimates have indicated.
Optical studies of Type IIb SN 2011dh

Abstract UBVRI photometry and low resolution optical spectroscopy of the type IIb SN 2011dh in M51 are presented, covering the first year after the explosion. The peak absolute magnitude in V-band of −17.12±0.18 mag indicates SN 2011dh to be a normal bright type IIb event. The peak quasi-bolometric luminosity indicates that ~ 0.06 M⊙ of 56Ni was synthesized in the explosion. The He I lines were detected in the spectra much before the maximum light in B-band. The nebular spectra of SN 2011dh show a box shaped emission in the red wing of [OI] 6300, 6363 line due to Hα emission excited because of shock-wave interaction. The analysis of the nebular spectra indicates a progenitor with a main sequence mass of 10-15 M⊙.
The effects of winds and coronae of hot stars on the infrared and radio continua

The theory of the formation of infrared and radio continua is extended to include the effects of steep temperature gradients and coronae. The presence of high-temperature zones in the winds from hot stars has been suggested by recent Copernicus satellite observations. We consider models in which the temperature is large only over a small range in radius. The density in the winds of hot stars is high enough for recombination to cool the flow where mechanical energy deposition ceases. Excess radiation at long wavelengths arises in the winds because of the lambda/sup 2/ dependence of free--free opacity. We find the coronal region causes a broad bump in the infrared continuum at about 20--100 . mu.m with a maximum excess of almost 2 mag. Variations of the distribution of density with height can also cause turnover in the continuous energy distribution; however, only temperature decreases, as occurs in the recombination region, can cause spectral gradients much steeper than the Rayleigh-Jeans gradient.
One-point modelling of rapidly deformed homogeneous turbulence

One-point turbulence models are important tools for engineering analysis. A good model should have a viscoelastic character, predicting turbulent stresses proportional to the mean strain rate for slow deformations and stresses determined by the amount of strain for rapid distortions. Our goal is to build a one-point turbulence model with this character, and this requires a one-point model for rapid distortions. Here it is shown that the turbulent stresses introduced by Osborne Reynolds do not, by themselves, provide an adequate tensorial base for one-point modelling of rapidly distorted turbulence because they do not carry critical information about the turbulence structure. The deficiency is shown to be most pronounced in flows subjected to strong mean rotation. Additional one-point tensors that do carry the missing information are introduced, and the complexities of a model that would have an adequate tensorial base are assessed. A new type of one-point structure-based turbulence model that overcomes the basic deficiency of Reynolds-stress transport models, but without the excessive complexity of multiple tensor variables, is then described. The ideas behind the rapid distortion version of this new model are presented, along with results for some special cases.
Cylinder‐shaped ultrasonic motors based on conventional piezoelectric ceramics and novel single crystals

Two medium‐sized ultrasonic motors using the first‐order bending vibration (B1) of a cylinder with two free–free ends have been developed in this study. The cylinder‐shaped stators are 10 mm in diameter and 25 mm in length. They are based on novel Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystal and conventional Pb(Zr,Ti)O3 (PZT) ceramic. The stators of the motors were simulated by a finite element method. The main performances of the motors were measured. The results show that the PMN–PT‐crystal‐based motor with medium size overmatches the conventional PZT‐based motor with: wider exciting frequency; lower exciting voltage, and much larger mechanical output power. The largest revolution speed of the PMN–PT motor is 780 rpm and a maximum load of ∼0.008 N m.
Mathematical Basis and Validation of the Full Cavitation Model

Cavitating flows entail phase change and hence very large and steep density variations in the low pressure regions. These are also very sensitive to: (a) the formation and transport of vapor bubbles, (b) the turbulent fluctuations of pressure and velocity, and (c) the magnitude of noncondensible gases, which are dissolved or ingested in the operating liquid. The presented cavitation model accounts for all these first-order effects, and thus is named as the full cavitation model. The phase-change rate expressions are derived from a reduced form of Rayleigh-Plesset equation for bubble dynamics. These rates depend upon local flow conditions (pressure, velocities, turbulence) as well as fluid properties (saturation pressure, densities, and surface tension). The rate expressions employ two empirical constants, which have been calibrated with experimental data covering a very wide range of flow conditions, and do not require adjustments for different problems. The model has been implemented in an advanced, commercial, general-purpose CFD code, CFD-ACE+
Acoustic source strength measurements of cavitation noise in a water tunnel

An experimental investigation of the noise generated by cavitation in turbulent shear flow is reported. The cavitation is produced by the flow through a sharp‐edged orifice plate mounted in the test section of a 15.25‐cm‐diam water tunnel. The unique features of this experiment include the direct measurement of acoustic source strength using a reciprocity technique and the development of semi‐empirical scaling laws for the noise produced. The source strength measurement method is useful for water tunnel cavitation noise studies because it is nonintrusive; the noise is measured by a reciprocal transducer located outside of the test section, in air. The scaling laws for orifice plate cavitation noise are developed to include the effects of pressure drop across the plate, the mean velocity through the plate, the cavitation number, and the air content level of the water. These scaling formulas were verified by running a similar test in a 30.5‐cm water tunnel and comparing the measured source strength spectra .
A High-Resolution Topographic Correction Method for Clear-Sky Solar Irradiance Derived with a Numerical Weather Prediction Model

AbstractRugged terrain is a source of variability in the incoming solar radiation field, but the influence of terrain is still not properly included by most current numerical weather prediction (NWP) models. In this work, a downscaling postprocessing method for NWP-model solar irradiance through terrain effects is presented. It allows one to decrease the estimation bias caused by terrain shading and sky-view reduction, and to account for elevation variability, surface orientation, and surface albedo. The method has been applied to a case study in southern Spain using the Weather Research and Forecasting (WRF) mesoscale model with a spatial resolution of 30 arc s, resulting in disaggregated maps of 3 arc s. The validation was based on a radiometric network made of eight stations located in the Natural Park of Sierra Magina over an area of roughly 30 × 35 km2 and 12 carefully selected cloudless days during a year. Three of the stations were equipped with tilted pyranometers. Their inclination and aspect wer.
Folded dipoles and loops

In Section I the theory of linear arrays consisting of two or more closely spaced elements that are interconnected by lumped reactances is reviewed. Specific application is made to two-element end-loaded folded dipoles and monopoles constructed of conductors with different diameters, to series tuned three-wire folded dipoles and monopoles, and to a three-wire-line reactor and impedance transformer. In Section II the circular folded dipole or Halo antenna is treated.
On the swimming motion of spheroidal magnetotactic bacteria

We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model.
Sparse sufficient dimension reduction

Existing sufficient dimension reduction methods suffer from the fact that each dimension reduction component is a linear combination of all the original predictors, so that it is difficult to interpret the resulting estimates. We propose a unified estimation strategy, which combines a regression-type formulation of sufficient dimension reduction methods and shrinkage estimation, to produce sparse and accurate solutions. The method can be applied to most existing sufficient dimension reduction methods such as sliced inverse regression, sliced average variance estimation and principal Hessian directions. We demonstrate the effectiveness of the proposed method by both simulations and real data analysis. Copyright 2007, Oxford University Press.
Advances in H-mode physics for long-pulse operation on EAST

Since the 2012 International Atomic Energy Agency Fusion Energy Conference (IAEA-FEC), significant advances in both physics and technology has been made on the Experimental Advanced Superconducting Tomakak (EAST) toward a long-pulse stable high-confinement (H-mode) plasma regime. The experimental capabilities of EAST have been technically upgraded with the power enhancement (source power up to 26 MW) of the continuous-wave heating and current drive system, replacement of the upper graphite divertor with an ITER-like W monoblock divertor, and installation of a new internal cryopump in the upper divertor and a set of 16 in-vessel resonant magnetic perturbation (RMP) coils. This new upgrade enables EAST to be a unique operating device capable of investigating ITER-relevant long-pulse high-performance operations with dominant electron heating and low torque input within the next 5 years. Remarkable physics progress in controlling transient and steady-state divertor heat fluxes has been achieved on EAST, e.g. (i) edge-localized mode (ELM) mitigation/suppression with a number of attractive methods including lower hybrid wave (LHW), supersonic molecular beam injection (SMBI), RMPs, and real-time Li aerosol injection; and (ii) active control of steady-state power distribution by the synergy of LHW and SMBI. In the 2014 experimental campaign, a long-pulse high-performance H-mode plasma with H98 ∼ 1.2 has been obtained with a duration over 28 s (∼200 times the energy confinement time). In addition, several new experimental advances have been achieved in the last EAST campaign, including: (i) high-performance H-mode with βN ∼ 2 and stored plasma energy ∼220 kJ; (ii) H-mode plasma sustained by neutral beam injection (NBI) alone or modulated NBI with lower hybrid current drive (LHCD), for the first time in EAST; (iii) high current drive efficiency and nearly full noninductive plasmas maintained by the new 4.6 GHz LHCD system; (iv) demonstration of a quasi-snowflake divertor configuration; and (v) observation of a new edge-coherent mode and its effects on edge transport in H-mode plasmas.
Dynamical scaling for spinodal decomposition - a small-angle neutron scattering study of porous Vycor glass with fractal properties

A model is developed for analysing small-angle scattering data for systems undergoing spinodal decomposition. This model is expressed as an integration of a series of Fourier components of the density fluctuation A( beta ) sin( beta r+ phi ) based on Cahn's linear theory of spinodal decomposition. Hence the time evolution of the characteristic crossover phenomenon and the width of the crossover of the scaling function of the structure factor are predicted to be associated with the maximum spinodal wavenumber beta m and the correlation length xi m, respectively. The rough surfaces and fractal network of porous materials are also considered in the model. Results of calculations based on this model are compared with small-angle neutron scattering data for dry and wet porous Vycor glass and give an excellent agreement.
Nanodimensional spinel NiFe2O4 and ZnFe2O4 ferrites prepared by soft mechanochemical synthesis

NiFe2O4 and ZnFe2O4 ferrites have been prepared by soft mechanochemical synthesis. The formation of spinel phase and crystal structure of sintered powders were analyzed by X-ray diffraction, Raman spectroscopy, and transmission microscopy. In order to confirm phase formation and cation arrangement, Mossbauer measurements were done. Investigation of the magnetization as a function of magnetic field confirms an expected change of the degree of inversion in the spinel structure with the sintering. The electrical DC/resistivity/conductivity was measured in the temperature range of 298-423 K. Impedance spectroscopy was performed in the wide frequency range (100 Hz-10 MHz) at different temperatures.
What are the products of polyatomic ion--electron dissociative recombination reactions

A statistical theory of polyatomic ion--electron dissociative recombination reactions is presented and applied to the calculation of branching ratios for the various sets of neutral products of the reactions HCNH/sup +/+e, H/sub 3/O/sup +/+e, CH/sub 3//sup +/+e, and NH/sub 4//sup +/+e, all thought to be important in interstellar cloud chemistry.
Status of the high brilliance synchrotron light source BESSY-II

The high brilliance synchrotron light source BESSY II under construction at the WISTA Science and Technology Park at Berlin-Adlershof has by now passed major milestones with the completion of the injector complex. On April 3/sup rd/, 1997 a 50 MeV electron beam was stored on a stable orbit in the 10 Hz booster synchrotron. As all magnets and most of the other necessary hardware have successfully passed acceptance tests, installation of the 240 m DBA storage ring in 16-fold symmetry has started. A stored beam is expected for the 2nd quarter of 1998. The paper describes the present status of the project.
Recent developments in arc spraying

New trends in arc-spraying processes and materials are reviewed. The wide field of applications for arc-sprayed coatings is demonstrated and discussed. Coating systems against corrosion, against wear, and for special applications (e.g. coatings for casting molds or biocompatible layers on artificial implants) are described. New process variants, e.g. spraying with a controlled-wire feed system, use of a pulse power source, or vacuum-arc spraying with one or two wires, are expected to appear with further commercial applications of these techniques. >
Hall thruster plasma fluctuations identified as the E×B electron drift instability: Modeling and fitting on experimental data

Microturbulence has been implicated in anomalous transport at the exit of the Hall thruster, and recent simulations have shown the presence of an azimuthal wave which is believed to contribute to the electron axial mobility. In this paper, the 3D dispersion relation of this E×B electron drift instability is numerically solved. The mode is found to resemble an ion acoustic mode for low values of the magnetic field, as long as a non-vanishing component of the wave vector along the magnetic field is considered, and as long as the drift velocity is small compared to the electron thermal velocity. In these conditions, an analytical model of the dispersion relation for the instability is obtained and is shown to adequately describe the mode obtained numerically. This model is then fitted on the experimental dispersion relation obtained from the plasma of a Hall thruster by the collective light scattering diagnostic. The observed frequency-wave vector dependences are found to be similar to the dispersion relation of linear theory, and the fit provides a non-invasive measurement of the electron temperature and density.
From the Extremum Principle of Entransy Dissipation to Steady Balance Equations of Fluid Mechanics

In the present work, an extremum principle of entransy dissipation is developed by taking into account the contribution of fluid friction. It is found that this extremum principle of entransy dissipation leads to the same balance equations as given in continuum mechanics for the steady heat conduction and shear flow in an incompressible fluid.Copyright © 2010 by ASME
On the nonexistence of dimension reduction for $\ell2_2$ metrics.

An ‘ 2 metric is a metric such that p can be embedded isometrically into R d endowed with Euclidean norm, and the minimal possible d is the dimension associated with . A dimension reduction of an ‘ 2 metric is an embedding of into another ‘ 2 metric µ so that distances in µ are similar to those in and moreover, the dimension associated with µ is small. Much of the motivation in investigating dimension reductions in ‘ 2 comes from a result of Goemans which shows that if such metrics have good dimension reductions, then they embed well into ‘1 spaces. This in turn yields a rounding procedure to a host of semidefinite programming with good approximation guarantees. In this work we show that there is no dimension reduction ‘ 2 metrics in the following strong sense: for every function D(n) and for every n there exists an n point ‘ 2 metric such that for all embeddings of into an ‘ 2 metric µ with distortion at most D(n), the associated dimension of µ is at least n 1. This stands in striking contrast to the Johnson Lindenstrauss lemma which provides a logarithmic dimension reduction for ‘2 metrics.