Miracle-dz/UniFAR-FTUs huggingface dataset:
Thomson scattering from laser plasmas

Thomson scattering has recently been introduced as a fundamental diagnostic of plasma conditions and basic physical processes in dense, inertial confinement fusion plasmas. Experiments at the Nova laser facility [E. M. Campbell et al., Laser Part. Beams 9, 209 (1991)] have demonstrated accurate temporally and spatially resolved characterization of densities, electron temperatures, and average ionization levels by simultaneously observing Thomson scattered light from ion acoustic and electron plasma (Langmuir) fluctuations. In addition, observations of fast and slow ion acous- tic waves in two-ion species plasmas have also allowed an independent measurement of the ion temperature. These results have motivated the application of Thomson scattering in closed-geometry inertial confinement fusion hohlraums to benchmark integrated radiation-hydrodynamic modeling of fusion plasmas. For this purpose a high energy 4{omega} probe laser was implemented recently allowing ultraviolet Thomson scattering at various locations in high-density gas-filled hohlraum plasmas. In partic- ular, the observation of steep electron temperature gradients indicates that electron thermal transport is inhibited in these gas-filled hohlraums. Hydrodynamic calcula- tions which include an exact treatment of large-scale magnetic fields are in agreement with these findings. Moreover, the Thomson scattering data clearly indicate axial stagnation in these hohlraums by showing a fast rise of the ion temperature. Its timing is in good agreement with calculations indicating that the stagnating plasma will not deteriorate the implosion of the fusion capsules in ignition experiments.
Robust Modelling of DTARCH Models

-norm fit is constructed to test the model adequacy. This approach captures various nonlinear phenomena and stylized facts with desirable robustness. Simulations show that the L_1-estimators are robust against innovation distributions and accurate for a moderate sample size, and the proposed test is not only robust against innovation distributions but also powerful in discriminating the delay parameters and ARCH models. It is noted that the quasi-likelihood modelling approach used in ARCH models is inappropriate to DTARCH models in the presence of outliers and heavy tail innovations. Copyright 2005 Royal Economic Society
Falling film flow of a viscoelastic fluid along a wall

In this paper, we study the heat transfer in the fully developed flow of a viscoelastic fluid, a slag layer, down a vertical wall. A new constitutive relation for the stress tensor of this fluid is proposed, where the viscosity depends on the volume fraction, temperature, and shear rate. For the heat flux vector, we assume the Fourier's law of conduction with a constant thermal conductivity. The model is also capable of exhibiting normal stress effects. The governing equations are non‐dimensionalized and numerically solved to study the effects of various dimensionless parameters on the velocity, temperature, and volume fraction. The effect of the exponent in the Reynolds viscosity model is also discussed. The different cases of shear‐thinning and shear‐thickening, cooling and heating, are compared and discussed. The results indicate that the viscous dissipation and radiation (at the free surface) cause the temperature to be higher inside the flow domain. Copyright © 2013 John Wiley & Sons, Ltd.
Accurate and robust inverse Cholesky factorization

In this paper, an algorithm for an accurate matrix factorization based on Cholesky factorization for extremely ill-conditioned matrices is proposed. The Cholesky factorization is widely used for solving a system of linear equations whose coefficient matrix is symmetric and positive definite. However, it sometimes breaks down by the presence of an imaginary root due to the accumulation of rounding errors, even if the matrix is actually positive definite. To overcome this, a completely stable algorithm named inverse Cholesky factorization is investigated, which never breaks down as long as the matrix is symmetric and positive definite. The proposed algorithm consists of standard numerical algorithms and an accurate algorithm for dot products. Moreover, it is shown that the algorithm can also verify the positive definiteness of a given real symmetric matrix. Numerical results are presented for illustrating the performance of the proposed algorithms.
Stability studies and the origin of the n=1 mode in the SPHEX spheromak experiment

Oscillations with toroidal mode number n=1 are ubiquitous in helicity injected spheromaks and spherical tokamaks, and play a crucial role in current drive. It has been proposed that these arise from a current driven instability of the open flux tube. Stability calculations are presented to confirm this, and they are compared with experimental data from the Spheromak Experiment (SPHEX) [M. Rusbridge et al., Plasma Phys. Control. Fusion 39, 683 (1997)]. The equilibria are modelled as piece-wise constant μ profile force-free plasmas with different values for the μ in the open (μc) and closed (μa) flux regions. A stability map in μc,μa space is then calculated. The SPHEX experimental data is also reduced to the same space both as a culmination of direct single point measurements of μ and as a time history of the reconstructed equilibrium from a particular shot. The results show a favorable comparison of the stability map with experiment, both in magnitude and shape. The effect of inserting a central current-c.
Integrated design of supply chain networks with three echelons, multiple commodities and technology selection

We consider a strategic supply chain design problem with three echelons, multiple commodities and technology selection. We model the problem as a tri-echelon, capacitated facility location problem that decides on the location of plants and warehouses, their capacity and technology planning, the assignment of commodities to plants and the flow of commodities to warehouses and customer zones. We use a mixed-integer programming formulation strengthened by valid but redundant constraints and apply Lagrangean relaxation to decompose the problem by echelon. Lagrangean relaxation provides a lower bound that is calculated using an interior-point cutting plane method. Feasible solutions are generated using a primal heuristic that uses the solution of the subproblems. Unlike common practice in the literature, the decomposition does not aim at getting easy subproblems, but rather at getting subproblems that preserve most of the characteristics of the original problem. Not only does this provide a sharp lower bound but also leads to a simple and efficient primal heuristic. We can afford to have relatively difficult subproblems because the interior-point cutting plane method used to solve the Lagrangean dual makes clever and selective choices of the Lagrangean multipliers leading to fewer calls to the subproblems. Computational results indicate the efficiency of the approach in providing a sharp bound and in generating feasible solutions that are of high quality.
Modulation instability induced by nonlinear dispersion in nonlinear metamaterials

We show that modulation instability may occur even in the normal group-velocity dispersion regime, or in the case of no group-velocity dispersion in metamaterials with a nonlinear electric polarization. The physical origin of the modulation instability is the additional second-order nonlinear dispersion effect resulted from the combination of the linear dispersive magnetic permeability with the nonlinear electric polarization. Based on the Drude model, a numerical simulation is performed to confirm the theoretical predictions, and a detailed discussion on the role of the second-order nonlinear dispersion effect in modulation instability in both negative-index and positive-index regions of metamaterial is presented.
Dissipative Korteweg–de Vries description of Marangoni–Bénard oscillatory convection

For a horizontal liquid layer open to air and heated either from the air side or the liquid side, threshold values for the onset of oscillatory interfacial instability are provided, as well as the nonlinear evolution equation describing the deformable open surface. The latter equation is the dissipation‐modified Korteweg–de Vries evolution equation for solitary excitations in the liquid layer.
Multirate robust servomechanism controllers of linear delay systems using a hybrid structure

A multirate robust servomechanism controller design for a linear time delay system is presented. The proposed controller is constructed by using a preparatory continuous internal model followed by a multirate error feedback compensator. An optimal algorithm for choosing the controller parameters is also derived. The algorithm is derived by minimizing a squared deviation error performance index, and the practical optimal solution can simply be solved from a discrete-time algebraic Riccati equation. A distinctive feature of the algorithm is that an optimal pulse compensation is also employed to improve the transient characteristics. Such a pulse compensation tends to eliminate the undesired influence arising from the initial deviation from the ultimate steady-state. In particular, if the initial deviation from the ultimate steady-state is known, then the optimal pulse compensation can drive the system into the steady-state in a time no larger than the input delay time plus the sampling period.
Curvature-driven flows: a variational approach

This paper introduces a new mathematical approach to the study of time evolutions of solids $K(t)$ in n-space whose boundaries move with velocity equal to the weighted mean curvature derived from the boundary surface energy $\Phi (\partial K(t))$. These “flat $\Phi $ curvature flows” are limits of sequences of solutions to variational problems in which a sum of surface and bulk energy is minimized. The construction works equally well for smooth elliptic $\Phi $’s, for nondifferentiable crystalline $\Phi $’s, and for anything in between. The flows agree with classical smooth flows when the data is smooth and elliptic in any dimension and coincide with motion by crystalline curvature for polyhedral curves in the plane.
A theoretical study of the effects of wall conductivity, non-uniform magnetic fields and variable-area ducts on liquid-metal flows at high Hartmann number

Flows of incompressible, electrically conducting liquids along ducts with electrically insulating or weakly conducting walls situated in a strong magnetic field are analysed. Except over a short length along the duct where the magnetic field strength and/or the duct cross-sectional area vary, the duct is assumed to be straight and the field to be uniform and aligned at right angles to the duct. Magnitudes of the field strength B0 and the mean velocity V are taken to be such that the Hartmann number M [Gt ] 1, the interaction parameter N (= M2/Re) [Gt ] 1 (Re being the Reynolds number of the flow) and the magnetic Reynolds number Rm [Lt ] 1. For an O(1) change in the product VB0 along the duct across the non-uniform region, it is shown that: (i) In the non-uniform region the streamlines and current flow lines follow surfaces containing the field lines satisfying $\int B^{-1}ds = {\rm constant}$, the integration being carried out along the field line within the duct; these surfaces are equipotentials and isobarics. This leads to (ii) a tube of stagnant, but not current-free fluid at the centre of the duct parallel to the field lines around which the flow divides to bypass it. To accommodate this flow, (iii) the usual uniform field/straight duct flow is disturbed over very large distances upstream and downstream of this region, the maximum length O(duct radius × M½) occurring in a non-conducting duct; (iv) a large pressure drop is introduced into the pressure distribution regardless of the direction of the flow, the effect being most severe in a non-conducting duct, where the drop is O(duct radius × (uniform field/straight duct pressure gradient) × M½); (v) in the part of the duct with the lower value of VB0 a region of reverse flow occurs near the centre of the duct and the stagnant fluid.
A matrix form of the Brunn-Minkowski inequality

The well known Brunn-Minkowski inequality (BMI) is one of the basic inequalities in geometry. The BMI is dual in some sense to the entropy-power inequality, which lower bounds the entropy power of the sum of independent random variables. The authors derive a matrix form for the BMI and discuss its applications. They note that the matrix BMI can be used to lower bound the volume of a projection of a lattice cell, and so it can find applications in calculating the effective number of codewords of lattice constellations or lattice quantizers satisfying spectral constraints.
Molecular filtered Rayleigh scattering applied to combustion

Molecular filtered Rayleigh scattering (FRS), employing an iodine vapour filter and an injection-seeded Nd:YAG laser, was utilized to measure instantaneous and average temperature fields in combustion environments. With FRS thermometry, the vapour within the cell strongly absorbs background scattering from surfaces and particles, while much of the Doppler-broadened Rayleigh scattering is not absorbed by the iodine transition; the gas temperature can then be deduced from the measured transmission of the molecular Rayleigh scattering. For demonstration purposes and to evaluate the accuracy of the technique, we employed a near-adiabatic hydrogen-air flame. The accuracy of the FRS measurements was investigated by comparing FRS-derived temperatures with those (1) calculated assuming adiabatic equilibrium conditions and (2) recorded with the CARS (coherent anti-Stokes Raman spectroscopy) technique. For the hydrogen-air flames, the FRS method gave temperatures within 2% of the expected value. The FRS thermometry instrument was then applied to a stagnation-flow, premixed methane-air flame; images recorded here demonstrate the utility of the FRS method for temperature imaging, particularly near surfaces. In this flow field, we compared the FRS temperatures with those from a one-dimensional model and investigated the radial extent of the uniform temperature region, to assess the assumption of one-dimensionality. In addition, we demonstrated the feasibility of simultaneous measurements of the temperature and velocity fields, the latter derived from the particle image velocimetry technique.
Crystal structure and physical properties of Mo2B: First-principle calculations

Several decades ago, Mo2B was assumed to have an Al2Cu-type structure with I4/mcm space group. Using ab initio phonon calculations, we identify the earlier proposed Al2Cu-type structure is dynamically unstable at ambient pressure. An energetically more favorable phase with the tetragonal I4/m structure was then predicted by employing frozen-phonon technique. The currently predicted I4/m phase is mechanically and dynamically stable and energetically more favorable than that of the earlier proposed Al2Cu-type structure. The electronic structures calculations indicate that Mo2B is a metal with several bands crossing the Fermi level. Our analysis indicates that the three-dimensional network of the covalent Mo-B bond is responsible for the ultra-incompressible property of Mo2B.
Experimental Observation of the rf-Driven Current by the Lower-Hybrid Wave in a Tokamak

It is observed that the waves launched from a phased array antenna of four waveguides couple effectively with electrons under the condition of $\frac{{\ensuremath{\omega}}_{0}}{{\ensuremath{\omega}}_{1h}(0)}\ensuremath{\gtrsim}2.0$. This coupling generates a rf-driven current, rather than heating of the bulk electrons, and the current/rf-power ratio of 110 A/kW was obtained with a rf power of 125 kW radiated into a plasma which included appreciable suprathermal electrons.
Magnetic and recording characteristics of Cr, Ta, W and Zr pre-coated glass disks

Magnetic and recording characteristics of CoCrPt/CrTi media which are deposited on Cr, Ta, W and Zr pre-coated glass disks, are examined. High S* was obtained on Ta and Zr. The largest output signal and the lowest DC-erase and recording noise were obtained on Ta. The recording noise on Zr pre-coated disk was second lowest. When the pre-coating thickness is increased, H/sub c/ on Ta increased by 700 Oe but the H/sub c/ increase on Zr was small. On the other hand, the DC-erase noise stayed constant and the recording noise decreased on Ta and both DC-erase noise and recording noise slightly increased on Zr. The /spl delta/M measurement revealed that the increase of Ta thickness caused the reduction of magnetic interaction between CoCrPt crystals. Strong Co(110)/Cr(100) orientation was observed on Ta and no major difference in crystal grain size was observed between Ta, Zr pre-coated media. The low DC-erase noise characteristics on Ta pre-coating would be attributed mainly to strong in-plane c-axis orientation.
Study of Flow over a Step Cylinder

Flow over a step cylinder at ReD = 2000 and D/d = 2 was investigated using a URANS-based numerical approach. The results illustrate the downstream development and interaction of wake vortices and identify streamwise vortical structures originating at the step. The observed flow development is shown to be in agreement with experimental results. Also, a comparison of the computational results and previous experimental findings is carried out for the drag coefficient and the pressure coefficient.
Uses and Applications of Climate Forecasts for Power Utilities

Abstract The uses and potential applications of climate forecasts for electric and gas utilities were assessed 1) to discern needs for improving climate forecasts and guiding future research, and 2) to assist utilities in making wise use of forecasts. In-depth structured interviews were conducted with 56 decision makers in six utilities to assess existing and potential uses of climate forecasts. Only 3 of the 56 use forecasts. Eighty percent of those sampled envisioned applications of climate forecasts, given certain changes and additional information. Primary applications exist in power trading, load forecasting, fuel acquisition, and systems planning, with slight differences in interests between utilities. Utility staff understand probability-based forecasts but desire climatological information related to forecasted outcomes, including analogs similar to the forecasts, and explanations of the forecasts. Desired lead times vary from a week to three months, along with forecasts of up to four seasons ahea.
Estimation following a Sequentially Designed Experiment

Abstract We investigate the design of experiments for the nonparametric estimation of the root of an unknown regression function. Approaches to this problem include the Robbins-Monro (1951), Venter (1967), and Lai-Robbins (1979, 1981) stochastic approximation procedures and Wu's (1985, 1986) sequential maximum likelihood estimators. Because the regression function is not assumed to belong to a parametric family, only experimentation near to the root is informative and the sequential design should converge to the root. After the sequential design has been generated, there are at least two distinct methods for estimation of the root: (a) estimate the root by the last design point, or (b) fit a parametric model. Except for Ruppert (1988) and simulation studies by Bodt (1985) and Bodt and Tingey (1990), all studies known to us of stochastic approximation procedures used the last design point as the estimator. Wu (1985, 1986) fit a generalized linear model. When the last design point is the estimator, then cle.
UvA-DARE Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at √sNN = 2.76 TeV with the ATLAS detector at the LHC

: The distributions of event-by-event harmonic ﬂow coeﬃcients v n for n = 2– 4 are measured in √ s NN = 2 . 76 TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum p T > 0 . 5 GeV and in the pseudorapidity range | η | < 2 . 5 in a dataset of approximately 7 µ b − 1 recorded in 2010. The shapes of the v n distributions suggest that the associated ﬂow vectors are described by a two-dimensional Gaussian function in central collisions for v 2 and over most of the measured centrality range for v 3 and v 4 . Signiﬁcant deviations from this function are observed for v 2 in mid-central and peripheral collisions, and a small deviation is observed for v 3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The v n distributions are also measured independently for charged particles with 0 . 5 < p T < 1 GeV and p T > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two p T ranges. The v n distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation eﬀects. Both models fail to describe the experimental data consistently over most of the measured centrality range.
Nonadiabatic transport features in the outer cusp region

The dayside to nightside circulation of plasma along the magnetopause inside the magnetosphere is examined by means of three-dimensional single-particle codes. It is demonstrated that particles incident upon the outer cusp region experience transient non-adiabatic motions, owing to a localized minimum in the field magnitude. Here, possibly large magnetic moment changes yield injection into the loss cone of fractions of the incoming population or, alternatively, enhanced bouncing motions at high altitudes. It is shown that particles gaining access to the magnetotail over the polar cap are progressively extracted from the weak field region by the large-scale convection electric field. In this latter case, the trajectory simulations suggest an implicit entry boundary into the nightside magnetosphere, which corresponds to the sunward edge of field lines featuring monotonic decrease of the field magnitude along their length. 29 refs.
Simulation of wind pressure on circular cylinder at super-critical reynolds number

Application of the computer simulation for solving the incompressible flow problems motivates developing efficient and accurate numerical models. In this paper, the accuracy of two-dimensional incompressible flow solver of the Numerical Analyzer for Scientific and Industrial Requirements (NASIR) for the solution flow around circular cylinder at supercritical Reynolds number is assessed by comparison of computed results with experimental coefficient of pressure measurements. 2D Navier-stokes equations for an incompressible fluid combined with a SGS eddy viscosity model to simulate turbulent viscosity flow and satisfactory results are obtained by the use of proper boundary conditions. The computed results are presented in terms of color coded maps of pressure and velocity fields as well as velocity vectors on boundary surfaces of the solution domain.