Miracle-dz/UniFAR-FTUs huggingface dataset:
Robust multigrid algorithms for the Navier-Strokes equations

Abstract Anisotropies occur naturally in computational fluid dynamics where the simulation of small-scale physical phenomena, such as boundary layers at high Reynolds numbers, causes the grid to be highly stretched, leading to a slowdown in convergence of multigrid methods. Several approaches aimed at making multigrid a robust solver have been proposed and analyzed in the literature using the scalar diffusion equation. However, they have rarely been applied to solving more complicated models, such as the incompressible Navier–Stokes equations. This paper contains the first published numerical results of the behavior of two popular robust multigrid approaches (alternating-plane smoothers combined with standard coarsening and plane-implicit smoothers combined with semi-coarsening) for solving the 3-D incompressible Navier–Stokes equations in the simulation of the driven-cavity and a boundary layer over a flat plate on a stretched grid. Grid size, grid stretching, and Reynolds number are the factors considered in evaluating the robustness of the multigrid methods. Both approaches yield large increases in convergence rates over cell-implicit smoothers on stretched grids. The combination of plane-implicit smoothers and semi-coarsening was found to be fully robust in the flat-plate simulation up to Reynolds numbers 10 6 and the best alternative in the driven-cavity simulation for Reynolds numbers above 10 3 . The alternating-plane approach exhibits a better behavior for lower Reynolds numbers (below 10 3 ) in the driven-cavity simulation.
The Relationship between Ninth Graders’ Perceptions of Teacher Equity and Their Math Identity: Differences by Student Race and School Racial Composition

Using data on ninth graders, math teachers, and schools from the nationally representative High School Longitudinal Study of 2009, we investigate the following questions: (1) How do ninth graders’ perceptions of their math teachers as equitable relate to their math identity at the intersection of adolescents’ race and gender? and (2) Do differences in the percentage of students at the school who share the adolescent’s race moderate (i.e., differentiate) the salience of perceptions of math teachers for adolescents’ math identities? Our results suggest that adolescents who perceive their math teachers as equitable typically have higher levels of math identity regardless of their race or gender. Adolescents’ perceptions of their math teachers as equitable are most salient for adolescents’ math identity in racially diverse schools, where racial differences and stereotypes may be more visible. Findings also indicate the seeming resistance of Black youth to racist stereotypes, whose math identity remains high regardless of their perceptions of their teachers.
Effects of Hydrogen Dilution Ratio on Properties of Hydrogenated Nanocrystalline Cubic Silicon Carbide Films Deposited by Very High-Frequency Plasma-Enhanced Chemical Vapor Deposition

We have successfully deposited nanocrystalline cubic silicon carbide (nc-3C-SiC:H) films at a low substrate temperature of 360 °C by very high-frequency plasma-enhanced chemical vapor deposition using monomethylsilane and hydrogen. Spectroscopic ellipsometry revealed that the crystalline volume fraction of the films increased from 69 to 92% with increasing hydrogen dilution ratio from 100 to 500. We found that the dark conductivity of the films was strongly affected by the crystalline volume fraction. A high deposition rate of 0.15 nm/s was achieved under a low hydrogen dilution ratio of 100.
Theories of tempered fractional calculus applied to tempered fractional Langevin and Vasicek equations

Our main goal in the current research work is to explore proofs of newly discovered theorems related to tempered fractional calculus. We use a new mechanism, namely, the natural tempered fractional transformation method, which can be used to solve important tempered fractional differential equations that are important in science, such as the linear and nonlinear tempered fractional differential equations. Indeed, we found new exact solutions to both tempered fractional Langevin and Vasicek differential equations and an exact solution for the famous tempered fractional diffusion equation. The new method makes it easier to do the calculations than with the traditional methods, and all you need is a few simple manipulations. Our new research technique is straightforward to use and highly accurate.
A solver combining reduced basis and convergence acceleration with applications to non‐linear elasticity

An iterative solver is proposed to solve the family of linear equations arising from the numerical computation of non‐linear problems. This solver relies on two quantities coming from previous steps of the computations: the preconditioning matrix is a matrix that has been factorized at an earlier step and previously computed vectors yield a reduced basis. The principle is to define an increment in two sub‐steps. In the first sub‐step, only the projection of the unknown on a reduced subspace is incremented and the projection of the equation on the reduced subspace is satisfied exactly. In the second sub‐step, the full equation is solved approximately with the help of the preconditioner. Last, the convergence of the sequences is accelerated by a well‐known method, the modified minimal polynomial extrapolation. This algorithm assessed by classical benchmarks coming from shell buckling analysis. Finally, its insertion in path following techniques is discussed. This leads to non‐linear solvers with few matrix factorizations and few iterations. Copyright © 2009 John Wiley & Sons, Ltd.
Inﬂuence of non-adiabatic temperature variations on line pro(cid:12)le variations of slowly rotating (cid:12) Cephei stars and SPBs ? II. Simulations of line pro(cid:12)le time series

We investigate to what extent non-adiabatic temperature variations at the surface of slowly rotating non-radially pulsating (cid:12) Cephei stars and slowly pulsating B stars a(cid:11)ect silicon line pro(cid:12)le variations. We use the non-adiabatic amplitudes of the e(cid:11)ective temperature and gravity variation presented in Dupret et al. (2002), together with a Kurucz intensity grid, to compute time series of line pro(cid:12)le variations. Our simulations point out that the line shapes do not change signi(cid:12)cantly due to temperature variations. We (cid:12)nd equivalent width variations of at most two percent of the mean equivalent width. We confront our results with observational equivalent width variations and with photometrically obtained e(cid:11)ective temperature variations.
Utilizing Response Time Distributions for Item Selection in CAT

Traditional methods for item selection in computerized adaptive testing only focus on item information without taking into consideration the time required to answer an item. As a result, some examinees may receive a set of items that take a very long time to finish, and information is not accrued as efficiently as possible. The authors propose two item-selection criteria that utilize information from a lognormal model for response times. The first modifies the maximum information criterion to maximize information per time unit. The second is an inverse time-weighted version of a-stratification that takes advantage of the response time model, but achieves more balanced item exposure than the information-based techniques. Simulations are conducted to compare these procedures against their counterparts that ignore response times, and efficiency of estimation, time-required, and item exposure rates are assessed.
A census of the physical parameters of nearby galaxies

Abstract We combine together physical parameters estimates for a large sample of galaxies drawn from the Sloan Digital Sky Survey Data Release Two (SDSS DR2), spanning wide ranges in galaxy properties, in order to provide a census of the physical parameters of galaxies in the local Universe. Stellar metallicities, masses and ages for this sample have been estimated comparing the strengths of selected absorption features in each observed spectrum to a comprehensive Monte Carlo library of star formation histories, following a Bayesian statistical approach. This allows us also to derive the total amount of metals locked up in stars today, and hence the average stellar metallicity of galaxies in the local Universe, finding a value of $1.03^{+0.14}_{-0.15} Z_\odot$. We also quantify the relative contribution to the total densities of mass and metals in stars from galaxies with different properties.
Factorization-based planar mapping method for generating intermediate views

Planar mapping approach for generating intermediate views is presented. Whereas most existing mapping procedure employ matching and/or point-patching strategies, the proposed method is based on transformation of moments using a factorization formulation. The extended factorization method makes it possible to obtain shape parameters with planar surfaces. The technique is applied to map the texture of an object with many surfaces as an demonstration of its utility.
Quantum Dots in Vertical Nanowire Devices

The research described in this thesis is aimed at constructing a quantum interface between a single electron spin and a photon, using a nanowire quantum dot. Such a quantum interface enables information transfer from a local electron spin to the polarization of a photon for long distance readout. Important aspects for the realization of such a device are the optical quality of the quantum dot and access to the optical polarization. In this thesis, we demonstrate high quality nanowire quantum dots and observe spin memory. By embedding them in a vertical nanowire device, we are able to isolate a single electron on the dot, while maintaining access to the intrinsic polarization properties of the nanowire quantum dot. These results demonstrate that quantum dots in vertical nanowire device are promising as an optical interface for single electron spins.
The effect on the second smallest eigenvalue of the normalized Laplacian of a graph by grafting edges

Let G be a connected graph and be its normalized Laplacian matrix. Let λ1 be the second smallest eigenvalue of and f be its corresponding harmonic eigenfunction. In this article we investigate the properties of the harmonic eigenfunction f on blocks of G. Next we use this result to characterize the effect on the second smallest normalized Laplacian eigenvalue by grafting edges.
Growth of Few-Layer Graphene on Sapphire Substrates by Directly Depositing Carbon Atoms

Few-layer graphene (FLG) is successfully grown on sapphire substrates by directly depositing carbon atoms at the substrate temperature of 1300°C in a molecular beam epitaxy chamber. The reflection high energy diffraction, Raman spectroscopy and near-edge x-ray absorption fine structure are used to characterize the sample, which confirm the formation of graphene layers. The mean domain size of FLG is around 29.2 nm and the layer number is about 2–3. The results demonstrate that the grown FLG displays a turbostratic stacking structure similar to that of the FLG produced by annealing C-terminated α-SiC surface.
Primes of the Form n! ± 1 and 2 ⋅3 ⋅5 ⋯p ± 1

All primes less than 101000 of the form n\± 1 or 2 • 3 • 5 • • ■ p ± 1 are determined. Results of Brillhart, Lehmer, and Selfridge are used together with a fast algorithm that applies to primality tests of integers N for which many factors of N ± 1 are known. Let p% denote the product of all primes that are < p; for example 7# = 2 • 3 ■ 5 • 7 = 210. In this paper we settle the question of the primality of all numbers of the form n\ + l, n\ — 1, p% + 1, or p% — 1 that contain not more than one thousand digits. This means that all n < 450 and p < 2371 were considered (though the calculations were actually carried somewhat further as described below). Our work confirms the results on numbers of the form n\ +1 and p% + 1 in [2] (for n < 100 andp < 307) and [5] (for n < 230 andp < 1031). The basic technique was to find possible primes by a pseudoprimality test and to then prove primality by a variant of the method described in [3]. The first section below contains the results and an outline of the basic methods. The proof of primality for numbers of the form p# ± 1 was greatly expedited by a fast divide-andconquer algorithm; this is described in the second section. All computations were done on a PDP 11-70 equipped with a UNIX operating system; both the C language and assembly language were used. 1. Let N > 1 be an odd integer. For the purposes of this paper, we will say that N is a pseudoprime if a(iv-i)/2 = _lmodiV for "several" integers a > 2, for which the Jacobi symbol (j¡) is equal to -1. It is easy to see that if N — n\±\ (respectively p% ± 1), then the Jacobi symbol (f) is equal to 1 for all a less than n (respectively p) so the search was started at the first prime larger than n (respectivelyp). If JV is a pseudoprime, then it is virtually certain to be prime; if N fails the pseudoprimality test, then it is definitely composite. Because of the number of integers considered and their size it was necessary to write efficient computer routines (e.g., computing am mod N quickly) in assembly language. The technique used to show that a pseudoprime was actually a prime is a variant of a standard procedure based upon a partial factorization of N ± 1. To consider the most basic example, suppose that the factorization of A^ — 1 is known: N1 =][pap. Received June 15, 1981. 1980 Mathematics Subject Classification. Primary 10A25, Secondary 10A10. ©1982 American Mathematical Society 0025-5718/81 /0000-1118/S02.25 639 License or copyright restrictions may apply to redistribution; see https://www.ams. org/journal-terms-of-use 640 J. P. BUHLER, R. E. CRANDALL AND M. A. PENK Then N is a prime if one can find a set S of primes that divide N — 1 such that
Construction of a mathematical model of vehicles tangent collision during reconstruction of the circumstances of a road accident

This paper considers the task to clarify the circumstances of a traffic accident (TA) involving two vehicles as a result of their lateral tangential collision at low angles. The aim of the study is to construct a mathematical model of a tangential collision of vehicles for the reconstruction of TA circumstances. Owing to the combination of the law of conservation of momentum and the theory of impact using the coefficient of recovery, it was possible to construct a mathematical model that describes the development of such an accident and makes it possible to determine the main parameters of the movement of vehicles after and before the collision. An answer is given regarding the possibility of losing the directional stability of the vehicle and its movement in the lateral direction because of a collision. Based on the mathematical model, the basic parameters of vehicles motion after their side collision at angles of 5–15° were analytically determined, when there are no slip marks on the road surface. A numerical experiment was conducted on the example of a specific accident. The findings make it possible to argue about the possibility of losing the directional stability of vehicles and shifting them to the oncoming lane or curb as a result of collision. A comparison of the results of the numerical calculation with the results of software modeling of accidents and the circumstances that were established in the process of studying a real accident was carried out. It was concluded that the results obtained are consistent and make it possible to more accurately assess the parameters of the movement of vehicles after their lateral tangential collision. In general, this produces more objective results of the reconstruction of TA mechanism in cases where there are no traces of slipping and braking on the road surface. The proposed mathematical model could be used in collisions accompanied by minor deformations or damage to vehicles
Upstream waves at Mars: Phobos observations

The region upstream from the Mars subsolar bow shock is surveyed for the presence of MHD wave phenomena using the high temporal resolution data from the MAGMA magnetometer. Strong turbulence is observed when the magnetic field is connected to the Mars bow shock in such a way as to allow diffuse ions to reach the spacecraft. On 2 occasions this turbulence occurred upon crossing the Phobos orbit. Also weak, {minus}0.15 nT, waves are observed at the proton gyro frequency. These waves are left-hand elliptically polarized and may be associated with the pick-up of protons from the Mars hydrogen exosphere.
Creep behavior of graphene oxide reinforced cement composites: Experiments, numerical simulations, and prediction models

The effect of graphene oxide (GO) on the creep behavior of cement composites was investigated macroscopically using a four‐bar spring compression creepmeter. The mechanism of the impact of GO on the creep behavior of hardened cement paste was microscopically identified using a molecular dynamics method. By analyzing commonly used rheological models, a viscoelastic‐plastic model was proposed to reflect the creep behavior of GO‐enhanced cement composites. The experimental results show that incorporating GO can increase the elastic modulus of calcium silicate hydrate (CSH) gels. The increase of micromechanical properties leads to a substantial reduction of creep. Compared to the reference group (0% GO), the creep behavior of cement composites with the GO incorporation of 0.02% and 0.03% decreases by 49.5% and 60.9%, respectively. Furthermore, the parameter fitting results indicate that the improved Burgers rheological model can better reflect the effect of GO on regulating the creep behavior of cement composites. Finally, we concluded the impact of GO addition on microscopic elastic modulus, viscoelastic deformation, and viscous deformation parameters, by providing new ideas for regulating the creep behavior of cement composites.
Encoderless Control of PMa-SynRG Based-Stator Current Vector for Wind Generation Systems

In this paper, a novel encoderless control of permanent magnet assisted synchronous reluctance generator (PMa-SynRG) based-stator current vector for renewable energy systems is presented. For the encoderless control, the PMa-SynRG rotor position angle along with rotor angular speed are estimated ultimately from the generator's stator currents, as the stator inductance is only requisite nevertheless the stator resistance. Indeed, this encoderless control technique employs one current control loop for regulating the magnitude of the stator current instead of employing two current control loops. For eliminating the current measurement noise and enhancing the phase angle tracking performance, a modified second-order generalized integrator frequency-locked loop (MSOGI-FLL) technique is employed and compared with the standard SOGI-FLL under different voltage/frequency conditions. The proposed technique has a simple computational implementation while accomplishing a rapid along with precise estimation performance of the PMa-SynRG rotor position angle and speed. The performance is validated using simulations and real-time hardware-in-the-loop Typhoon HIL implementation.
A note on the maximum likelihoood estimators for the location and scatter parameters of a multivariate cauchy distribution

The likelihood function of a multivariate Cauchy distribution with unknown location and scatter parameters in ρ dimensions has a unique maximum provided the sample is in general position and is of size n > p + 1 (see Kent and Tyler 1991 and Kent et al., 1994). In this paper, we show that when n=p+l, the maximum of the locationscatter Cauchy likelihood function occurs when the parameters lie on a ρ–dimensional surface.
Variational Estimates for the Effective Response of Shape Memory Alloy Actuated Fiber Composites

The homogenization procedure of Ponte Castaneda is used to estimate the effective behavior of active composite materials consisting of aligned shape memory alloy (SMA) fibers embedded in a linear elastic matrix. Results are presented for thermal activation of the SMA with various applied tractions on the composite. While increasing stiffness of the matrix phase inhibits the contraction of the SMA, the simulations indicate that the use of a prestress in the manufacturing of the composite may provide an increase in the response time of the system without reducing performance. ©2002 ASME
OUTBURSTS OF DWARF NOVAE.

A review is given of the observational facts related to the outbursts of dwarf novae and of relevant aspects of the theory of accretion disks. It now appears possible to explain the outbursts of dwarf novae in terms of a nonstationary accretion behavior. Between the outbursts, the material supplied by the secondary component is stored in the relatively cool disk. This eventually leads to a local thermal instability which results in the increase of the viscosity and of the local accretion rate. As the instability propagates across the disk, the global increase in the accretion rate is observed as an outburst. By constructing disk models based on different viscosity approximations and comparing them with observations of dwarf novae it may be possible to obtain some clues concerning the nature of the viscosity. Super-outbursts in the SU UMa objects appear to be a consequence of sudden mass-transfer bursts which are - most likely - due to an instability of the secondary component.
Evidence for narrow dibaryons at 2050, 2122, and 2150 MeV observed in inelastic pp scattering

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Evidence for narrow dibaryons at 2050, 2122, and 2150 MeV observed in inelastic pp scattering B. Tatischeff, J. Yonnet, M. Boivin, M.P. Comets, P. Courtat, R. Gacougnolle, Y. Le Bornec, E. Loireleux, F. Reide, N. Willis
Analysis of the thermoelectric properties of n-type ZnO

We report an investigation of the temperature- and doping-dependent thermoelectric behavior of n-type ZnO. The results are based on a combination of experimental data from the literature and calculated transport functions obtained from Boltzmann transport theory applied to the first-principles electronic structure. From this we obtain the dependence of the figure of merit ZT on doping and temperature. We find that improvement of the lattice thermal conductivity is essential for obtaining high ZT in n-type ZnO.