Miracle-dz/UniFAR-FTUs huggingface dataset:
The differential quadrature solution of nonlinear reaction–diffusion and wave equations using several time‐integration schemes

Three different time‐integration schemes, namely the finite difference method (FDM) with a relaxation parameter, the least‐squares method (LSM) and the finite element method (FEM), are applied to the differential quadrature (DQM) solution of one‐dimensional nonlinear reaction–diffusion and wave equations. In the solution procedure, the space derivatives are discretized using DQM, which may also be used without the need of boundary conditions. The aim of the paper is to find computationally more efficient time‐integration algorithm by comparison. For the nonlinear reaction–diffusion equation, which is a parabolic type, FEM is found to be the method of choice in terms of accuracy and computational cost. For the nonlinear wave equation, it is seen that both the FDM and LSM are better than FEM. Therefore, LSM can be preferred as a direct method for the nonlinear wave equation. Copyright © 2009 John Wiley & Sons, Ltd.
Closed fringe demodulation by multipolynomial fitting

In this paper, a set of polynomials are calculated to approximate the phase from a single closed fringe pattern image or interferogram. A scanning window is used to carry out the demodulation process. A polynomial function is fitted over the sub-image obtained from each scanning window. Then, the scanning window is moved on an overlapped neighbourhood of the previous one and the process is repeated. The coefficient polynomial optimization is achieved by multiple application of a genetic algorithm (GA). The GA optimizes a cost function which considers the irradiance similitude between original interferogram and fringes generated by the polynomial obtained from chromosome decodification, the smoothness of the phase being demodulated, and the phase similitude between the overlapped area of actual and previous scanning window. Closed fringe patterns with broad bandwidth can be demodulated. Preliminary results are presented.
Book review: The relative biological effectiveness of radiations of different quality

The Relative Biological Effectiveness of Radiations of Different Quality is a survey of the literature relevant to the selection of relative biological effectiveness values for use in arriving at values of Q for neutrons and other particles with a high rate of linear energy transfer. Except for internal emitters, there is no data on which RBE for high-LET radiations can be estimated for humans. The focus of this report is on RBE data from plant and animal studies to the almost total exclusion of RBE data from human studies.
Inference to the Best Explanation: Is It Really Different from Mill's Methods?

Peter Lipton has attempted to flesh out a model of Inference to the Best Explanation (IBE) by clarifying explanation in terms of a causal model. But Lipton's account of explanation makes an adequate explanation depend on a principle which is virtually identical to Mill's Method of Difference. This has the result of collapsing IBE on Lipton's account of it into causal inference as conceived by the Causal-Inference model of induction. According to this model, many of our inductions are inferences from effects to their probable causes, and Mill's Methods are canons to guide such inferences. Thus, Lipton's account of IBE fails to represent an advance over the already familiar Causal-Inference Model of induction.
Stochastic Lorenz 63 Equations

Two different types of perturbations of the Lorenz 63 dynamical system for Rayleigh-Bénard convection by multiplicative noise – called stochastic transport (ST) noise and fluctuation-dissipation (FD) noise – are found to produce qualitatively different effects. For example, ST noise preserves the sum of the deterministic Lyapunov exponents, while FD noise does not. In the process of making this comparison between effects of ST and FD noise on the Lorenz 63 system, a stochastic version of a robust, reasonably accurate, deterministic numerical algorithm for obtaining the individual Lyapunov exponents was developed. With this stochastic version of the algorithm, the value of the sum of the Lyapunov exponents differs from the deterministic case at the first decimal place for the FD noise and agrees to five decimal places for the ST noise.
Simulation of fast Alfvén wave interaction with beam ions over a range of cyclotron harmonics in DIII-D tokamak

To study fast Alfvén wave damping on fast ions, a Monte-Carlo code, ORBIT-RF, has been coupled with a 2D full wave code, TORIC4. The ORBIT-RF/TORIC4 combination has been applied to DIII-D experimental conditions to investigate fast wave (FW) heating of injected beam ions over a range of ion cyclotron harmonics. ORBIT-RF using a single dominant toroidal and poloidal Fourier wave number qualitatively reproduces the strong FW–beam interaction at 60 MHz (4ΩD and 5ΩD) and the much weaker interaction at 116 MHz (8ΩD) in DIII-D L-mode plasmas, consistent with experimental observations. The result at 8ΩD differs from linear theory prediction using a Maxwellian to model the fast ion distribution function, suggesting the importance of finite orbit effect, Coulomb collisions for transport across flux surfaces and details of the non-Maxwellian fast ion distribution.
Pattern recognition in the prediction of protein structure. I. Tripeptide conformational probabilities calculated from the amino acid sequence

A procedure that uses pattern recognition techniques to compute tripeptide conformational probabilities is described. The procedure differs in several respects from the many “secondary structure” prediction algorithms that have been published over the last 20 years. First, the procedure classifies tripeptides into 64 different conformational types, rather than just α, β and coil, as is commonly done. Thus, the procedure can attempt to predict regions of irregular structure. Second, the procedure uses the methods of pattern recognition, which are powerful but conceptually simple. In this approach, amino acid properties are used to map peptide sequences into a multivariate property space. Particular tripeptide conformations tend to map to particular regions of the property space. These regions are represented by multivariate gaussian distributions, where the parameters of the distributions are determined from tripeptides in the protein X‐ray data bank. Finally, rather than making simple predictions, the procedure computes probabilities. Tripeptide conformational probabilities are calculated in the multivariate property space using the gaussian distributions. In a prediction, the procedure might find that a particular tripeptide in a protein has a 36% chance of being in the ααα conformation, a 17% chance of being ααϵ, a 14% chance of being ααα*, etc. The α‐helical conformation is thus the most probable, but, in predicting the structure of the protein, a search algorithm should also consider some of the other possibilities. The values of the probability provide a rational basis for selecting from among the possible conformations. The second article of this series describes a procedure that uses the probabilities to direct a search through the conformational space of a protein. The third article of the series describes a procedure that generates actual three‐dimensional structures, and minimizes their energies. The three articles together describe a complete procedure, termed “pattern recognition‐based importance‐sampling minimization” (PRISM), for predicting protein structure from amino acid sequence.
A resource selection model for analyzing pseudoreplicated data due to grouping behavior of animals

Quantifying resource selection is of primary interest in animal ecology. Many analyses of resource selection assume spatial and temporal independence of the sampling unit. Autocorrelation between observations, which is a general property of ecological variables, causes difficulties for most standard statistical procedures of resource selection because autocorrelated data violate the assumption of independence. To overcome this problem, we develop a mixed-effects model to estimate resource selection functions from data that are autocorrelated because of unobserved grouping behavior by animals. In the application of the expectation-maximization (EM) algorithm, the computation of the conditional expectation of the complete-data log-likelihood function does not have a closed-form solution requiring numerical integration. A Monte Carlo EM algorithm with Gibbs sampling can be used effectively in such situations to find exact maximum likelihood estimates. We propose a simple automated Monte Carlo EM algorithm with multiple sequences in which the Monte Carlo sample size is increased when the EM step is swamped by Monte Carlo errors.We demonstrate that the model can detect inherent autocorrelation and provide reasonable variance estimates when applied to nocturnal bird migration data. This approach could also be applied to ecological processes with various types of spatially and temporally autocorrelated data, circumventing serious problems caused by dangerous pseudoreplication.
Formation of Small-Scale Cyclones in Numerical Simulations of Synoptic-Scale Baroclinic Wave Life Cycles: Secondary Instability at the Cusp

An examination of high-resolution simulations of nonlinear baroclinic wave evolution, based upon the nonhydrostatic anelastic equations, has revealed the occurrence of frontal instabilities following cutoff of the primary wave occlusion. The frontal waves are shallow and have horizontal scales of approximately 700 km. They derive their energy from both baroclinic and barotropic energy conversions and it is suggested that they may owe their existence to the instability of a strip of anomalously large potential vorticity that develops along the surface front. The issue of the fundamental mechanism is complicated somewhat because such secondary cyclogenesis events occur at the frontal cusp, a location in which the flow is highly nonparallel. 28 refs., 9 figs.
Anytime discovery of a diverse set of patterns with Monte Carlo tree search. (Découverte d'un ensemble diversifié de motifs avec la recherche arborescente de Monte Carlo)

The discovery of patterns that strongly distinguish one class label from another is still a challenging data-mining task. Subgroup Discovery (SD) is a formal pattern mining framework that enables the construction of intelligible classifiers, and, most importantly, to elicit interesting hypotheses from the data. However, SD still faces two major issues: (i) how to define appropriate quality measures to characterize the interestingness of a pattern; (ii) how to select an accurate heuristic search technique when exhaustive enumeration of the pattern space is unfeasible. The first issue has been tackled by Exceptional Model Mining (EMM) for discovering patterns that
Roundoff noise in digital filters: Frequency transformations and invariants

The family of filters {H(F(z)):F(z) a frequency transformation} generated from a prototype filter H(z) is shown to possess certain common properties. These are coordinate-free quantities (called second-order modes) which are invariant under frequency transformation. The invariance is significant in the design of low-noise fixed-point digital filter structures since the second-order modes characterize the minimum attainable noise. Filter structures (including parallel, cascade, and ladder configurations) are studied whose output noise is essentially independent of bandwidth and center frequency. An analysis of direct form structures (whether isolated or as one section within a cascade or parallel configuration) results in an expression giving the dominant term in the output noise as a function of the parameter in the low-pass-low-pass transformation. This noise term approaches infinity as bandwidth approaches zero. Thus, for narrowband filters, a difference of several orders of magnitude in the output noise can exist between a scaled direct form (having six multiplications per two-pole section) and the optimal form (having nine multiplications per two-pole section).
Discovery and imaging of a Galactic cirrus cloud with the far ultraviolet space telescope

We present new far-ultraviolet (1400-1800 A) data concerning a Galactic cirrus cloud G251.2+73.3 near the north Galactic pole obtained with the space-borne imaging telescope FAUST (Far Ultraviolet Space Telescope). We obtain a good correlation between the far-ultraviolet (FUV) and IRAS 100 micrometers surface brightnesses, their relation being I(sub FUV) = (128 +/- 3) I(sub 100 micrometers) - (264 +/- 9), where the I(sub FUV) flux is given in units of photon/s/sq cm/A/sr and I(sub 100 micrometers) in MJy/sr. Using uvbyH-beta photometry, we get a distance of 120 pc and a visual extinction in the center of the cloud of 0.39 mag corresponding to an extinction of 1.0 mag at 1565 A. We have performed a multiple scattering calculation for the scattered light using the Monte Carlo method. These calculations provide restrictions on the FUV scattering properties of the interstellar dust.
The structure of the interstellar medium at the 25 AU scale

A three-station VLBI Galactic H I absorption experiment has been carried out with baselines up to 600 km. The large collecting area of the European VLBI Network consisting of the Lovell Telescope (Mark Ia), the 100 m telescope at Effelsberg, and the Westerbork Synthesis Radio Telescope was necessary to achieve adequate sensitivity for these high angular resolution (0.05 arcsec) and high-velocity resolution (0.5 km/s) observations. The extragalactic sources 3C 138, 3C 147, and 3C 380 were observed. Changes in the local H I apparent absorption were observed in all three sources as a function of resolution. The changes are most striking in the direction of 3C 138. The implied linear diameters are in the range 25 AU with typical H I densities of 10,000-100,000/cu cm. 19 refs.
Enhanced nonlinearity by H-bonded polymer–dye complex in liquid crystal for holographic gratings

We have studied a new heterogeneous liquid-crystalline material where H-bonded polymer–azo-dye complexes are used as dopants to the liquid crystal (LC) bulk at a very low concentration. Double enhancement of the holographic gratings’ diffraction efficiency occurred in the complex-doped LC compared to dye-doped LC. The grating formation/relaxation processes in complex-doped LC showed anomalies that were explained by the presence of polymer with H bonds. The gratings appeared to be formed due to a change of both the absorption coefficient and refractive index. Using such complexes as dopants gives perspectives for tuning and control of the LC properties, and for possible optical applications.
Minimizing movements of the Mumford and Shah energy

We study a simplified model of fracture propagation introduced by L. Ambrosio and A. Braides, based on the evolution by minimizing movements of the Mumford-Shah energy. In the two-dimensional case, we show that under a few additional assumptions on the "fracture" the movement solves the heat equation, with (weak) Neumann boundary conditions, and we are able to give some estimate on the decrease of the Mumford-Shah energy.
Development of a Technique to Locate and Quantify a Crack in a Beam Based on Modal Parameters

A model-based algorithm has been developed, in order to locate and quantify the size of a crack, based on free vibration measurements of a cracked beam. Measured natural frequencies (at least two) and corresponding mode shapes of the cracked beam are used in the identification algorithm. The Euler-Bernoulli beam theory is used to model the beam. The crack of the beam is modeled through standard five crack flexibility coefficients, by considering bending effects only. Damping is assumed to be Rayleigh's damping. The finite element method is used in the simulation of the cracked beam. The present algorithm is iterative in nature and the iterations are carried out until the estimated and assumed crack depth ratios (as well as its location) become close up to the desired accuracy. The applicability of the algorithm has been tested through numerical examples and is found to be adequate even in the presence of the measurement noise in modes shapes and measurement errors in natural frequencies.
Tra-DBScan: A Algorithm of Clustering Trajectories

Accompany with fast development of location technology, more and more trajectories datasets are collected on the real applications. So it is something of value in the theory and applied research to mine the clusters from these datasets. In this paper, a trajectory clustering algorithm, called Density-Based Spatial Clustering of Application with noise (Tra-DBSCAN for short), based on DBSCAN that is a classic clustering algorithm. In this framework, each trajectory firstly partitions into sub-trajectories as clustering object, and then line hausdorff distance is used to measure the distance between two sub-trajectories. Next, DBSCAN is introduced to cluster sub-trajectory to form cluster area, and then connecting different moments of clustering area is regarded as trajectory movement patterns. Finally, the experimental results show our framework’s effective.
Some Issues in the Psychology of Mathematics Instruction.

Given a large proportion of students failing to learn basic skills in mathematics, the problem of improving mathematics learning may be illuminated by an examination of contemporary learning research and theory. Three major phases can be seen in the performance of a mathematical task: translating from a verbal problem statement to a mathematical expression, carrying out an operation on the expression, and validating the solution. Less attention in instruction and research should be given to the classification of tasks as abstract or concrete, and more attention to the deliberate teaching of correct rules and the advantages of making computational operations automatic. Each performance phase has its implications for instruction, and all could be more fully addressed by research.
Self-field Loss in AC Transport Current Loss of MgB_2 Superconducting Composites

The measurement and analysis of AC transport current loss (self-field loss) in MgB2 superconducting composites were studied. In experimental results, the normalized Ic dependency of AC loss in the MgB2 deviated from Norris' theoretical curve. Then a numerical analysis was performed by taking into consideration the model of a round superconducting wire that consisted of three concentric layers. The analysis clearly showed the experimentally obtained results, such as that the phenomenon originated in the inhomogeneity of the critical current density in the wire rod section.
A Numerical Survey of Transient Co-orbitals of the Terrestrial Planets

Abstract We have investigated numerically the evolution of near-Earth asteroids (3753) Cruithne, (3362) Khufu, 1989 VA, (10563) 1993 WD, and 1994 TF2 that enter the coorbital regions of the Earth or Venus. We show that the coorbital libration modes identified in F. Namouni (1999, Icarus 137, 293–314) and F. Namouni et al. (1999, Phys. Rev. Lett. 83, 2506–2509) are strong enough to survive tens of thousands of years under planetary perturbations in the Solar System. We give a detailed analysis of the nature of libration modes as functions of the argument of perihelion. The effects of close approaches with the coorbiting planet as well as neighboring planets are characterized. Based on these results, we argue for a steady-state flux of objects temporarily captured in coorbital configurations with the planets.
The Role of Small Soluble Aerosols in the Microphysics of Deep Maritime Clouds

Some observational evidence—such as bimodal drop size distributions, comparatively high concentrations of supercooled drops at upper levels, high concentrations of small ice crystals in cloud anvils leading to high optical depth, and lightning in the eyewalls of hurricanes—indicates that the traditional view of the microphysics of deep tropical maritime clouds requires, possibly, some revisions. In the present study it is shown that the observed phenomena listed above can be attributed to the presence of small cloud condensation nuclei (CCN) with diameters less than about 0.05 mm. An increase in vertical velocity above cloud base can lead to an increase in supersaturation and to activation of the smallest CCN, resulting in production of new droplets several kilometers above the cloud base. A significant increase in supersaturation can be also caused byadecreaseindropletconcentrationduringintensewarmrainformationaccompaniedbyanintensevertical velocity. This increase in supersaturation also can trigger in-cloud nucleation and formation of small droplets. Another reason for an increase in supersaturation and in-cloud nucleation can be riming, resulting in a decrease in droplet concentration. It has been shown that successive growth of new nucleated droplets increases supercooled water content and leads to significant ice crystal concentrations aloft. The analysis of the synergetic effect of thesmallest CCNand giantCCNon production ofsupercooledwater andice crystals in cloud anvils allows reconsideration of the role of giant CCN. Significant effects of small aerosols on precipitation and cloud updrafts have been found. The possible role of these small aerosols as well as small aerosols with combination of giant CCN in creating conditions favorable for lightning in deep maritime clouds is discussed.
Effects of Y and Zn atoms on the elastic properties of Mg solid solution from first‐principles calculations

The effects of Y and Zn atoms on elastic properties of Mg solid solution are investigated by first‐principles calculations based on density function theory. Five supercell models (Mg96, Mg95Y1, Mg94Y2, Mg95Zn1 and Mg94Zn2) are adopted to simulate the variation of solute atoms content. Structural optimization is performed firstly, and then the five independent elastic constants of Mg solid solution are calculated. The bulk modulus B, shear modulus G, Young's modulus E and Poisson ratio ν are also derived by Voigt–Reuss–Hill (VRH) approximation, indicating a strong dependence of the elastic modulus on concentration of the solute atoms. Using the bulk modulus/shear modulus ratio (B/G), the change in the ductility of Mg solid solution with the solute atom content is further studied. In the end, the electronic density of states (DOS) is calculated and discussed.
Contact angle hysteresis on random surfaces

Contact angle hysteresis on weakly heterogeneous surfaces is studied using an extension of Imry and Ma's analysis of the random field problem. Deformations of the liquid-vapor interface in response to the heterogeneity are characterized by a length Ld which increases as the magnitude of the heterogeneity decreases. The characteristic energy associated with these deformations is used to find the scale of contact angle hysteresis. In the absence of gravity, contact angle hysteresis occurs for arbitrarily weak heterogeneity. Hysteresis disappears when Ld exceeds the gravitational capillary length, while systems with characteristic size less than Ld show increased hysteresis.
New synthesis techniques for high order all-pole filters

A new method for partitioning a high order all-pole filter into an interconnection of subsystems is described. It was found that conventional all-cascade and all-parallel implementations were unsuitable and the theory of filter implementations is enhanced by appealing to polynomial theory. This theory is presented, prefaced by a description of the context in which the work was done, and followed by some examples. It is shown that, for high order models, the filter coefficients exhibit far less variation between maximum and minimum absolute values, making them more practical to implement.