Miracle-dz/UniFAR-FTUs huggingface dataset:
Tunable mechanical properties of diamond superlattices generated by interlayer bonding in twisted bilayer graphene

Using molecular-dynamics simulations of tensile deformation and shear loading tests, we determine the mechanical properties of superlattices of diamond-like nanocrystals embedded in twisted bilayer graphene (TBG) generated by covalent interlayer bonding through patterned hydrogenation. We find that the mechanical properties of these superstructures can be precisely tuned by controlling the fraction of sp3-hybridized C-C bonds in the material, fsp3, through the extent of chemical functionalization. The Young modulus and ultimate tensile strength weaken compared with pristine TBG with increasing fsp3, but they remain superior to those of most conventional materials. The interlayer shear modulus increases monotonically with fsp3.
Computations of Turbulent Flow and Heat Transfer Through a Three-Dimensional Nonaxisymmetric Blade Passage

The design of a three-dimensional nonaxisymmetric end wall is carried out using three-dimensional numerical simulations. The computations have been conducted both for the flat and contoured end walls. The performance of the end wall is evaluated by comparing the heat transfer and total pressure loss reduction. The contouring is done in such a way to have convex curvature in the pressure side and concave surface in the suction side. The convex surface increases the velocity by reducing the local static pressure, while the concave surface decreases the velocity by increasing the local pressure. The profiling of the end wall is done by combining two curves, one that varies in the streamwise direction, while the other varies in the pitchwise direction. Several contoured end walls are created by varying the streamwise variation while keeping the pitchwise curve constant. The flow near the contoured end wall is seen to be significantly different from that near the flat end wall. The contoured end wall is found to reduce the secondary flow by decreasing radial pressure gradient. The total pressure loss is also lower and the average heat transfer reduces by about 8% compared to the flat end wall. Local reductions in heat transfer are significant (factor of 3). This study demonstrates the potential of three-dimensional endwall contouring for reducing the thermal loading on the end wall.
On the flux ratio method and correcting incorrect forms of correct equations

Solow and Benton (2010) claim to have corrected an error in two mirror-image equations used to estimate underlying historical rates of taxonomic invalidation and revalidation (Alroy 2002). These equations are important because they can be used to infer the proportion of currently accepted taxonomic names that are actually synonyms. Whenever this proportion is large, absolute counts of taxa are inflated and diversity trends are likely to be distorted. However, Solow and Benton's versions of these equations and mine are not the same, and their corrected versions of their incorrect equations simply restate my original ones. Let q and and r be the per-taxonomic name, per-year rates of invalidation and revalidation. I originally stated my equations in the following single sentence (Alroy 2002): “Maximum-likelihood estimates of q and r are simply the numbers of invalidations or revalidations [emphasis added] divided by the sums across taxa of the number of years that they have been considered valid or invalid. ” Solow and Benton (2010) also cited …
Structural Equation Modeling in Language Testing and Learning Research: A Review

Despite the recent increase of structural equation modeling (SEM) in language testing and learning research and Kunnan's (1998) call for the proper use of SEM to produce useful findings, there seem to be no reviews about how SEM is applied in these areas or about the extent to which the current application accords with appropriate practices. To narrow these gaps, we investigated the characteristics of the use of SEM in language testing and learning research. Electronic and manual searches of 20 journals revealed 50 articles containing a total of 360 models analyzed using SEM. We discovered that SEM was most often used to investigate learners' strategy use and trait/test structure. Maximum likelihood methods were most often used to estimate parameters of a model; model fit indices of chi-squares, comparative fit index, root mean square error of approximation, and Tucker–Lewis index were often reported, but standardized root mean square residual rarely was. Univariate and multivariate normality checks were infrequently reported, as was missing data treatment. Sample sizes, when judged according to Kline's (2005) and Raykov and Marcoulides's (2006) guidelines, were in most cases adequate, and LISREL was the most widely used program. Two recommendations are provided for the better practice of using and reporting SEM for language testing and learning research.
Diffraction scattering and the parton structure of hadrons

We apply parton-model concepts to the ''soft'' (small-momentum- transfer) processes which make up the majority of the hadronic total cross section. Diffraction is calculated as the shadow of these soft processes. We obtain an attractive picture of the essential features of total, elastic, and diffractive-inelastic scattering. In particular, the rather large cross section for inelastic diffraction, which is observed experimentally, results from fluctuations in the distribution of the wee partons which initiate interactions. These fluctuations lead to diffractive production by the mechanism of Good and Walker. The observed peripheral character of diffraction as a function of impact parameter, the absence of a forward dip in dsigma/dt dm/sup 2/, the correct integrated cross section, and the correct small-t slope of diffraction all follow naturally in our approach.
Unified Practical Formulas for Vibration-Based Method of Cable Tension Estimation

In this paper, unified practical formulas are proposed to estimate cable tension for vibrations under different boundaries. Correction coefficients are applied to the cable tensions calculated from the taut string theory. In these formulas, a dimensionless parameter η is introduced to represent the relative bending stiffness of the cable in lieu of the dimensionless parameter ξ in the previous formulas found in practice. Results have shown that the proposed formulas are accurate. For the fixed-fixed boundaries, the error in the estimated cable tensions for various frequencies is less than 3% for η ≤ 0.88, and less than 1% for η ≤ 0.55. For the fixed-hinged boundaries, the error in the estimated cable tensions for various frequencies is less than 1% for η ≤ 0.9. If there are multiple frequencies in the in-situ measurement, the proposed formulas can be used to identify the cable tension and bending stiffness simultaneously by solving a quadratic equation. The proposed formulas have been validated against several numerical examples as well as practical test cases.
On the converse to the iterated logarithm law

Let Xi, i = 1, 2, 3,… be a sequence of independent and identically distributed random variables with law ℓ(X) and write. if EX = 0 and EX2 = σ2 < ∞, the law of the iterated logarithm (Hartman and Wintner [1]) tells us that
A Proposal for Estimation of the Parameters of Multivariate Moving‐average Models

A method is proposed for the preliminary estimation of the parameters of multivariate moving‐average processes. Initially,m independent white‐noise series are generated. Then the parameters are estimated through an iterative procedure. The algorithm is fast and simple since it does not require specialized software for time series but a least squares routine. The estimators are consistent and a simulation experiment shows good performance in finite samples. An applicati on to real data is also illustrated
Planetary camera observations of the central parsec of M32

Analysis of V band HST Planetary Camera images of the elliptical galaxy M32 shows that its nucleus is extremely dense and remains unresolved at even the HST diffraction limit. A combined approach of image deconvolution and model fitting is used to investigate the starlight distribution into limiting radii of 0". 04 (0.14 pc at 700 kpc). The logarithmic slope of the brightness profile smoothly flattens from y= -1.2 at 3.4 pc to y= -0.5 at 0.34 pc; interior to this radius the profile is equally consistent with a singular µ(r)∝ r,^(-1/2) cusp or a small nonisothermal core with r_c<0.37 pc. The isophotes maintain constant ellipticity into tlle center, and there is no evidence for a central point source, disk, dust, or any other substructures. The cusp model implies central mass densities p_0 > 3 X 10^7 M_☉ pc^(-3) at the resolution limit and is consistent with a central M_• = 3 X 10^6 M_☉ black hole; the core model implies p_0≈4 X 10^6 M_☉ pc^(-3). From the viewpoint of long-term stability, we argue that a starlight cusp surrounding a central black hole is the more plausible interpretation of the observations. A core at the implied density and size without a black hole has a relaxation time of only ~7 X 10^7 yr and a short stellar oollision timescale implying wholesale stellar merging over the age of the universe. The core would be strongly vulnerable to collapse and concomitant runaway stellar merging. Collapse may lead to formation of a massive black hole in any case if it cannot be reversed by formation of a binary from high-mass merger products. Regardless of the ultimate fate of the core, however, structural evolution of the core will always be accompanied by strong evolution of the core population-the constant isophote shape and absence of a central color gradient appear to show that such evolution has not occurred. In contrast, the high velocities around a black hole imply long relaxation and stellar collision times for the cusp population compared to the age of the universe.
Asymptotic normality of M-estimators in nonhomogeneous hidden Markov models

Results on asymptotic normality for the maximum likelihood estimate in hidden Markov models are extended in two directions. The stationarity assumption is relaxed, which allows for a covariate process influencing the hidden Markov process. Furthermore, a class of estimating equations is considered instead of the maximum likelihood estimate. The basic ingredients are mixing properties of the process and a general central limit theorem for weakly dependent variables.
Magnetization switching in alternating width nanowire arrays

A systematic investigation of the magnetization reversal mechanism in arrays of Ni80Fe20 nanowires with alternating width is presented. The structures were fabricated using deep ultraviolet lithography followed by lift-off technique at 248 nm exposure wavelength. We have mapped the magnetization reversal processes and observed that the switching mechanism is very sensitive to the thickness to width ratio of the nanowires. For wire thickness, t 40 nm, spin rotation dominates the reversal process. For t 40 nm, however, the reversal process is mediated by the curling mode of reversal. The dipolar field is strongly influenced by the nanowire of larger width in the alternating width array. Our results were compared with homogeneous width nanowire array of similar thicknesses and marked differences were observed.
Acoustic investigation of the elastic properties of ZnO films

The elastic properties of ZnO films deposited by rf magnetron sputtering on Al2O3 substrates have been analyzed by means of an acoustic investigation technique. The phase velocities of a spectrum of acoustic modes propagating along the layered structure have been measured and the results exploited for determining the complete set of elastic constants of the film. The effective constants of the film are lower than those of the bulk material by amounts which depend on the elastic constant considered and range from −1.2% for c33 to −24.8% for c11. The values obtained were used for determining the dispersion curves of acoustic modes propagating along ZnO layers deposited on fused quartz and silicon and showed good agreement with experimental results.
Optimal Splines for Rigid Motion Systems: A Convex Programming Framework

This paper develops a general framework to synthesize optimal polynomial splines for rigid motion systems driven by cams or servomotors. This framework is based on numerical optimization, and has three main characteristics: (i) Spline knot locations are optimized through an indirect approach, based on providing a large number of fixed, uniformly distributed candidate knots; (ii) in order to efficiently solve the corresponding large-scale optimization problem to global optimality, only design objectives and constraints are allowed that result in convex programs; and (iii) one-norm regularization is used as an effective tool for selecting the better (that is, having fewer active knots) solution if many equally optimal solutions exist. The framework is developed and validated based on a double-dwell benchmark problem for which an analytical solution exists.
Combination of kernel PCA and linear support vector machine for modeling a nonlinear relationship between bioactivity and molecular descriptors

In this paper, a two‐step nonlinear classification algorithm is proposed to model the structure–activity relationship (SAR) between bioactivities and molecular descriptors of compounds, which consists of kernel principal component analysis (KPCA) and linear support vector machines (KPCA + LSVM). KPCA is used to remove some uninformative gradients such as noises and then exactly capture the latent structure of the training dataset using some new variables called the principal components in the kernel‐defined feature space. LSVM makes full use of the maximal margin hyperplane to give the best generalization performance in the KPCA‐transformed space. The combination of KPCA and LSVM can effectively improve the prediction performance compared with the linear SVM as well as two nonlinear methods. Three datasets related to different categorical bioactivities of compounds are used to evaluate the performance of KPCA + LSVM. The results show that our algorithm is competitive. Copyright © 2011 John Wiley & Sons, Ltd.
The time lag between V and I in S5 0716+714 during the 1995 January 8 burst

The BL Lac object S5 0716+714 has been one part of our optical monitoring program of blazars since 1994. A burst with a duration of 6 hours was detected on 1995 January 8 and 80 sets of measurements were obtained in V and I, by turn, for the whole burst. An upper limit of the time lag of 0.0041 days (about six minutes) between bands V and I has been determined by using the Interpolation Cross-Correlation Function (ICCF) and the Discrete Correlation Function (DCF).
On squares, rectangles, rhombuses, ... and the influence of culture and language on students’ conceptions

In this paper we discuss the influence of cultural and linguistic factors on students’ understanding of some special types of quadrilaterals which are common in geometry lessons, namely the square, the rectangle, the rhombus, the parallelogram, and the trapezium. In this direction we examine a number of clinical interviews with 10th grade students. In particular we analyse, from a culture and linguistic viewpoint, the students’ difficulties with respect to the logical/conceptual structure of the above types of quadrilaterals.
Pinholes in thin low resistance MgO-based magnetic tunnel junctions probed by temperature dependent transport measurements

Magnetic tunnel junctions (MTJs) with thin crystalline MgO(001) barriers displaying large tunnel magnetoresistance (TMR) and low resistance-area product (R×A) will likely be used as the next generation sensors in read heads of ultrahigh density hard drives. However, the thin insulting barrier may result in the unwanted presence of metallic pinholes joining the two electrodes. Here we study the transport properties of thin MgO-based low resistance MTJs (barrier thickness, t=0.6nm), deposited by physical vapor deposition, with R×A values as low as 8Ωμm2 and TMR as high as 70% at room temperature. We performed temperature dependent (300–20K) resistance and magnetoresistance measurements on different samples of the same series and observed different behaviors for different samples and magnetic states. All samples showed positive dR∕dT for the parallel state due to the presence of pinholes in the barrier. However, in the antiparallel state the R(T) curves always exhibit a mixed character, with dR∕dT changing f.
The development of shear and compression elastic moduli in curing epoxy adhesives measured using non-contact ultrasonic transducers

Thin epoxy resin adhesive samples were ultrasonically measured during cure using normal incidence radially polarized shear wave electromagnetic acoustic transducers (EMATs). Although the EMATs used predominantly generated shear waves (SH) they were designed so that they also generated/detected compression waves allowing the simultaneous measurement of shear and compression wave propagation through a curing polymer in a non-contact regime. The adhesive thickness examined in the experiments was approximately 1 mm, which was optimal for experimental measurement using our apparatus. The epoxy resin systems (rapid cure and a standard cure) described in this paper were supplied in a two-part cartridge form, mixed by injection through a mixing nozzle. Five different samples have been investigated at this stage, and there appears to be a fundamental difference in the way that the elastic moduli develop in the rapid cure and longer cure time epoxies. This can possibly be explained in terms of the reaction kinetics and the development of the structure on a microscopic scale. The rapid cure systems initially develop a shear elastic modulus at a faster rate which suddenly decreases at approximately the same time that the temperature of the adhesive reaches its maximum value during the exothermic reaction. This is consistent with an initial rapid reaction rate which is then greatly reduced as the remaining un-reacted polymer chains require a finite time to move into a position where they can react and join the network.
On the diffusivity of holes in silicon

The longitudinal diffusion coefficient of holes in Si has been measured with time‐of‐flight and noise techniques at 300 K for field strengths ranging from about 0.5 up to 40 kV/cm. As the electric field increases, the diffusion coefficient decreases to about 0.3 of its Ohmic value much more sharply than results previously reported in literature. The experimental results are interpreted by a Monte Carlo simulation which includes warping and nonparabolicity effects of the heavy‐hole band.
Elimination Structures for Unsymmetric Sparse $LU$ Factors

The elimination tree is central to the study of Cholesky factorization of sparse symmetric positive definite matrices. In this paper, the elimination tree is generalized to a structure appropriate for the sparse $LU$ factorization of unsymmetric matrices. A pair of directed acyclic graphs, called elimination dags, is defined and they are used to characterize the zero-nonzero structures of the lower and upper triangular factors. These elimination structures are applied in a new algorithm to compute fill for sparse $LU$ factorization. Experimental results indicate that the new algorithm is usually faster than earlier methods.
Viscous flow around fluid spheres at intermediate reynolds numbers (II)

Approximate velocity profiles and terminal velocities have been predicted for fluid spheres moving in viscous media under the influence of gravity. The equations of motion were satisfied approximately using a numerical method after Kawaguti(1). Predicted terminal velocities are compared with literature data and with data measured by one of the authors(2). The agreement is reasonable for Reynolds numbers up to about 80. The effect of the asymmetry of the exterior flow upon the symmetry of the interior flow is discussed. Les auteurs predisent les profils de vitesse approximatifs et les vitesses terminales pour des spheres fluides qui se deplacent dans un milieu visqueux, sous l'influence de la gravite. On satisfait de facon approximative aux equations du mouvement en utilisant une methode numerique proposee par Kawaguti.1 On compare les vitesses terminales predites avec les donnees de la litterature et avec les valeurs mesurees par un des auteurs.2 L'accord est satisfaisant pour des nombres de Reynold allant jusqu'a 80. On discute l'effet de l'asymetrie de l'ecoulement exterieur sur la symetrie de l'ecoulement interieur.
Experimental Rarefied Density Flowfields at Hypersonic Conditions over 70-Degree Blunted Cone

At raree ed e ow regimes, e owe eld investigations have been conducted in the SR3 wind tunnel on a 70-deg sphericallybluntedconeanddensitye owe eldsobtained bynonintrusiveelectronbeam e uorescencemeasurements. Theblunted cone, chosen as thetest case model, has been thesubject of extensive studiesduring thepast few years. In addition to some limited results already presented at the Fourth European High-Velocity Database Workshop, the present research gathersdensity e owe elds obtained experimentally at two raree ed hypersonice ow conditions. Experiments have been performed at a freestream Mach number close to 20 and for two Reynolds numbers, 1420 and 4175, calculated using freestream conditions and the cone base diameter. Density e owe elds are presented for the two angles of attack, 0 and 10 deg, of the cone. In parallel to the experimental work presented, a number of e owe eld calculations were executed by an international group of researchers for test conditions identical to SR3 test conditions. Flowe elds were calculated using direct simulation Monte Carlo solutions, leading to comparisons between experimental and computational e owe elds.
Measurements of Binary Stars with the Starfire Optical Range Adaptive Optics Systems

To investigate the relative photometry produced by adaptive optics within the isoplanatic patch, we observed four binaries, 10 UMa, ϕ UMa, 81 Cnc, and κ UMa, with adaptive optics using natural guide stars on the 3.5 m telescope, as well as one binary, β Del, with adaptive optics using a laser guide star on the 1.5 m telescope at the Starfire Optical Range. Iterative blind deconvolution (IBD) and parametric blind deconvolution (PBD) techniques were used to postprocess the data, which produced consistent results for position angles, separations, and magnitude differences. We also conducted simulations that verify the agreement between IBD and PBD and compared their measurements to truth data. From the results of both observations and simulations, we conclude that adaptive optics is well suited for providing not only position angles and separations for close binaries, but also good relative magnitudes without quadrant ambiguity. From the observations, we find that the secondary of 81 Cnc (separation = 0.″12) appears to be 0.12 mag brighter than the primary at 0.85 μm and is, therefore, cooler. We also derive a new orbit for κ UMa (separation = 0.″067). Our results for β Del (ADS 14073) have significantly improved precision compared with the 1998 analyses of the same data by ten Brummelaar and colleagues and by Roberts, ten Brummelaar, and Mason.