Miracle-dz/UniFAR-FTUs huggingface dataset:
On transient relativistic thermodynamics and kinetic theory. Il

This paper, the sequel to Stewart (1977), discusses the relation between transient relativistic thermodynamics and kinetic theory in the formulation of Israel (1972, 1976) which differs (mathematically) from that of the previous paper. The difference is that the moment expansions are truncated in different ways. However, identical results for the characteristic velocities of thermal transients are obtained, and this lends credence to both approaches. In this approximation at least, the Grad method of moments is insensitive to the truncation procedure.
A novel robust proportional navigation guidance law design for missile considering autopilot dynamic

In this paper, a novel robust proportional navigation guidance (RPNG) law is derived for missiles by integrating sliding mode control theory and proportional navigation guidance law in order to achieve robustness against target accelerations. A first-order autopilot dynamic is taken into account in the state space equations of the nonlinear missile-target engagement dynamic. The robustness of the designed guidance law against external disturbances is proved by the second method of Lyapunov. Some coefficients that appear in the proposed RPNG law are obtained using the genetic algorithm. Performance of the new designed guidance law is compared with the well known augmented proportional navigation guidance (APNG) law. Considering different types of target accelerations and several scenarios, numerical simulations are presented. Simulation results show that the proposed guidance law has much better robustness in comparison with the APNG law. Moreover, it is simple and easy to implement from the point of view of practical applications.
Studies with a flexible new radiation code. I: Choosing a configuration for a large-scale model

A comprehensive new radiation code based on the two-stream equations in both the long-wave and short-wave spectral regions is described. The spectral resolution of the code is variable, enabling it to be used in a wide range of applications. Because of its flexibility, the code is well-suited to the investigation of the sensitivity of radiative calculations to changes in the way in which physical processes are parametrized. The gaseous transmission data are derived from a line-by-line model. Particular attention is directed towards the treatment of the water vapour continuum, the overlap between gases, and the sensitivity to changing the carbon dioxide concentrations. The performance of the code is examined both at high spectral resolution and in a lower-resolution configuration designed for the UK Meteorological Office Unified Forecast/Climate Model (UM). Particularly for use in the UM, the code must be shown to perform satisfactorily across the whole range of atmospheric conditions. Comparisons are therefore made with reference calculations in both the long-wave and the short-wave, in clear and cloudy skies, and the accuracy with which various processes may be represented is studied. For the cloudy calculations in the short-wave, a new method is presented for deriving the single-scattering properties in broad bands, based on the analytic expression for the reflectivity of an optically thick cloud. This minimizes the errors in calculating the short-wave radiative properties of water clouds when the spectral resolution is reduced to that designed for the UM. In contrast, for ice clouds the errors are minimized by deriving the single-scattering properties using linear averaging, as appropriate for optically thin clouds. In the long-wave, the vertical distribution of the radiative heating in cirrus clouds is examined at high spectral resolution. The effect of scattering of long-wave radiation, usually ignored in large-scale models, is examined in some detail and is explained using a simple model. Taking all these studies into account, it is concluded that the configuration designed for the UM retains the generality of the code, without significantly compromising the overall accuracy.
The rheology of concentrated suspensions of spheres in simple shear flow by numerical simulation

The newly developed simulation method known as Stokesian dynamics is used to investigate the rheological behaviour of concentrated suspensions. Both the detailed microstructure (e.g. pair-distribution function) and the macroscopic properties are determined for a suspension of identical rigid spherical particles in a simple shear flow. The suspended particles interact through both hydrodynamic and non-hydrodynamic forces. For suspensions with purely hydrodynamic forces, the increase in the suspension viscosity with volume fraction ϕ is shown to be caused by particle clustering. The cluster formation results from the lubrication forces, and the simulations of a monolayer of spheres show a scaling law for the cluster size: lc ∼ [1 − (ϕ/ϕm)½]−1, where ϕm is the maximum volume fraction that can shear homogeneously. The simulation results suggest that the suspension viscosity becomes infinite at the percolation-like threshold ϕm owing to the formation of an infinite cluster. The predicted simulation viscosities are in very good agreement with experiment. A suspension with short-range repulsive interparticle forces is also studied, and is seen to have a non-Newtonian rheology. Normal-stress differences arise owing to the anisotropic local structure created by the interparticle forces. The repulsive forces also reduce particle clustering, and as a result the suspension is shear-thickening.
The Robustness of Hotelling's T 2

Abstract Monte Carlo methods are used to study the effect of inequality of covariance matrices on the distribution of Hotelling's T 2 statistic. Samples are drawn from multivariate normal distributions and from them the distribution of T 2 is approximated. One minus the significance level is calculated for various departures from equality, for tests with a supposed significance level of . 05 and . 01. The power of the tests is also given. The number of variates considered is 1, 2, 3, 5, 7, and 10. The effect of sample size on level of significance and power is studied; both equal and unequal sample sizes are used. Let ∑1 and ∑2 be the two covariance matrices. Graphs are presented for one minus the significance level versus d, for the case where all eigenvalues of the matrix ∑2∑1 −1 are equal to d. One minus the significance level is also plotted against the sample size for the case of equal sample size and equal eigenvalues of ∑2∑1 −1. Power curves are also included for several ratios of sample size. In gen.
On metabelian groups of prime-power exponent

Gupta, Newman & Tobin (1968) show that in a metabelian group of exponent dividing pk, the subgroup generated by pk-1th powers is nilpotent. In this paper we obtain the ‘right’ bound for the class of this subgroup together with some information about the subgroup generated by phth powers, thus answering a question raised by Gupta et al.
First results from the Australia Telescope Compact Array 18‐GHz pilot survey

As a pilot study for the first all-sky radio survey at short wavelengths, we have observed 1216 deg 2 of the southern sky at 18 GHz (16 mm) using a novel wide-band (3.4-GHz bandwidth) analogue correlator on one baseline of the Australia Telescope Compact Array. We scanned a region of sky between declination -71° and -59° with an rms noise level of 15 mJy. Follow-up radio imaging of candidate sources above a 4σ detection limit of 60 mJy resulted in 221 confirmed detections, for which we have measured accurate positions and flux densities. For extragalactic sources, the survey is roughly 70 per cent complete at a flux density of 126 mJy and 95 per cent complete above 300 mJy. Almost half the detected sources lie within a few degrees of the Galactic plane, but there are 123 sources with |b| > 5', which can be assumed to be extragalactic. The differential source counts for extragalactic sources in the range 0.1 Jy ≤ S 18GHz ≤ 3 Jy are well fitted by a relation of the form n(S) = 57 (S/Jy) -2.2±0.2 Jy -1 sr -1 , in good agreement with the 15-GHz counts published by Taylor et al. and Waldram et al. Over 70 per cent of the extragalactic sources have a flat radio spectrum (α 18 0.843 > -0.5, S v v α ), and 29 per cent have inverted radio spectra (α 18 0.843 > 0). The optical identification rate is high: 51 per cent of the extragalactic sources are identified with stellar objects (candidate quasi-stellar objects), 22 per cent with galaxies and only 27 per cent with faint optical objects or blank fields.
74-fs nanotube-mode-locked fiber laser

We report an erbium-doped, nanotube mode-locked fiber oscillator generating 74 fs pulses with 63 nm spectral width. This all-fiber-based laser is a simple, low-cost source for time-resolved optical spectroscopy, as well as for many applications where high resolution driven by short pulse durations is required.
Influence of gender, single-sex and co-educational schooling on students’ enjoyment and achievement in mathematics

This research investigates the influence that gender, single-sex and co-educational schooling can have on students’ mathematics education in second-level Irish classrooms. Although gender differences in mathematics education have been the subject of research for many years, recent results from PISA (Programme for International Student Assessment) show that there are still marked differences between the achievement and attitude of male and female students in Irish mathematics classrooms. This paper examines the influence of gender in more detail and also investigates the impact of single-sex or co-educational schooling. This is a follow on study which further analyses data collected by the authors when they designed a pedagogical framework and used this to develop, implement and evaluate a teaching intervention in four second-level Irish schools. The aim of this pedagogical framework was to promote student interest in the topic of algebra through effective teaching of the domain. This paper further analyses the quantitative data collected and investigates whether there were differences in students’ enjoyment and achievement scores based on their gender and whether they attended single-sex or co-educational schools.
Auroral spirals at Saturn

We report observations of auroral spirals at Saturn propagating from midnight to noon via dawn, based on Cassini/UVIS measurements. The aurora during that sequence is observed for the first time to consist of detached features swirling as they propagate from dawn to early afternoon. The features have a diameter of ∼6000 km in the ionosphere, which would correspond to 12 to 15 RS wide plasma regions in the magnetosphere. Simultaneous ENA enhancements are observed; however, they do not show a clear spiral form. We estimate the velocity of the UV auroral features to decrease from 85% of rigid corotation (28°/h) near the equatorward edge to 68% of rigid corotation (22°/h) in the poleward edge. We discuss two possible scenarios which could explain the generation of the auroral spirals. First, we suggest that the auroral spirals could be related to large dynamic hot populations which create regions with strong velocity gradients. Alternatively, a less possible theory could be that the auroral spirals are related to field line deformation from the magnetosphere to the ionosphere, similar to the scenario proposed to explain auroral spirals at Earth. Such field line twist can happen for a configuration where the magnetospheric source region is located between a pair of plasma flow vortices.
A Three-Dimensional Numerical Model of the Sea Breezes Over South Florida

Abstract An eight-level three-dimensional primitive equation model which includes a detailed boundary layer parameterization scheme has been used to describe the initiation and evolution of sea-breeze convergence patterns over south Florida as a function of the surface heat and momentum fluxes and of the large-scale synoptic forcing. A minimum grid spacing of 11 km was used. Model results are presented for several different initial conditions and the results, when compared against cumulus cloud and shower patterns, demonstrate that the dry sea-breeze circulations are the dominant control on the locations of thunderstorm complexes over south Florida on undisturbed days. It is also shown that, in contrast to the differential roughness, the differential heating between land and water over south Florida is the primary determinant of the magnitudes of convergence. The values of surface roughness, however, indirectly influence convergence patterns by affecting the intensity of the vertical turbulent transport o.
Semantic Similarity Measure Based on Concreteness Degree of a Concept

Semantic similarity between concepts is widely used, but the measuring method is still a challenging task. We proposed a semantic similarity measuring method, using concreteness degree of a concept which is based on constructing process of ontology. Firstly, Concreteness degree of concept was defined for the concept by depth of the concept itself and its most specific descendant, then according to the Jaccards Coefficient the semantic similarity between concepts measured by the specified process of the two compared concepts and their co-specified process. Experiment result shows that the proposed method gained a higher correlation coefficient to human judgments than other compared measures.
Radical performance enhancements for combinatorial optimization algorithms based on the dead‐end elimination theorem

Recent advances in protein design have demonstrated the effectiveness of optimization algorithms based on the dead‐end elimination theorem. The algorithms solve the combinatorial problem of finding the optimal placement of side chains for a set of backbone coordinates. Although they are powerful tools, these algorithms have severe limitations when the number of side chain rotamers is large. This is due to the high‐order time dependence of the aspect of the calculation that deals with rotamer doubles. We present three independent algorithmic enhancements that significantly increase the speed of the doubles computation. These methods work by using quantities that are inexpensive to compute as a basis for forecasting which expensive calculations are worthwhile. One of the methods, the comparison of extrema, is derived from analytical considerations, and the remaining two, the “magic‐bullet” and the “qrs” and “quv” metrics, are based on empirical observation of the distribution of energies in the system. When used together, these methods effect an overall speed improvement of as much as a factor of 47, and for the doubles aspect of the calculation, a factor of 95. Together, these enhancements extend the envelope of inverse folding to larger proteins by making formerly intractable calculations attainable in reasonable computer time. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1505–1514, 1998
Boundary-layer transition and the behaviour of spiral vortices on rotating spheres

The mechanism of boundary-layer transition and the behaviour of spiral vortices on spheres rotating in otherwise undisturbed fluid were investigated experimentally. Critical and transition Reynolds numbers which determine the laminar-turbulent transition regime on the sphere surface were measured. In addition the number of spiral vortices on the sphere and the direction of the vortex axis were clarified.
An image warping approach to spatio‐temporal modelling

In this article we present a spatio‐temporal dynamic model that can be realized using image warping. Image warping is a non‐linear deformation which maps every point in one image plane to a point in another image plane. Using thin‐plate splines, these deformations are defined by how a small set of points is mapped, making the method computationally tractable. In our case the dynamics of the process is modelled by thin‐plate spline deformations and how they vary in time. Thus we make no assumption of stationarity in time. Finding the deformation between two images in the space–time series is a trade‐off between a good match of the images and a smooth, physically plausible, deformation. This is formulated as a penalized likelihood problem, where the likelihood measures how good the match is and the penalty comes from a prior model on the deformation. The dynamic model we suggest can be used to make forecasts and also to estimate the uncertainties associated with these. An introduction to image warping and thin‐plate splines is given as well as an application where the methodology is applied to the problem of nowcasting radar precipitation. Copyright © 2005 John Wiley & Sons, Ltd.
Contribution of the reflection to the attenuation properties of cancellous bone

The article deals with the contribution of reflection effects to the attenuation properties of cancellous bone. The bone behaviour is simulated by the multiscale finite element method, a numerical homogenization approach, suitable for the modelling of heterogeneous material with a highly oscillatory microstructure. The focus is on the modelling of a novel type of the representative volume element, which apart from the solid framework filled with fluid marrow also includes an infinitesimally thin ‘transition’ layer at the contact of the phases. The mentioned layer is implemented in order to simulate the amplitude transformation of an incident wave and to take the loss of energy caused by the reflection into account. The given numerical examples consider the simulation of wave propagation through a sample while the excitation frequency is varied. The numerical values are compared with the results which are determined without considering the reflection, in order to point out the contribution of the newly introduced phenomenon.
Non-analytic finite-size corrections in the one-dimensional Bose gas and Heisenberg chain

The energy spectra of the one-dimensional Bose gas and Heisenberg chain in an external field (chemical potential in the case of the Bose gas and magnetic field in the case of the Heisenberg chain) are calculated. It is found that, at general values of the external field, the spectra are not of the form expected on the basis of conformal invariance. The conformal structure can be recovered only if some extra conditions are imposed on the size of the system and the external field. It is argued that these additional conditions must be satisfied when taking the continuum limit in order to arrive at a conformally invariant theory.
Multistep Explicit Stereo Camera Calibration Approach to Improve Euclidean Accuracy of Large-Scale 3D Reconstruction

AbstractThe spatial accuracy of point clouds generated from a mobile stereo camera set is very sensitive to the intrinsic and extrinsic camera parameters (i.e., camera calibration) used in stereo image-based three-dimensional (3D) reconstruction methods. The existing camera calibration algorithms induce a significant amount of error owing to poor estimation accuracy in camera parameters when they are used for large-scale scenes such as mapping civil infrastructure. This leads to higher uncertainties in the location of 3D points, and may result in the failure of the whole reconstruction process. This paper proposes a novel procedure to address this problem. It hypothesizes that a set of multiple calibration parameters created by videotaping a moving calibration pattern along a specific path can increase overall calibration accuracy and ultimately enhance the Euclidean accuracy of the generated point cloud. This is achieved by using conventional camera calibration algorithms to perform separate estimations .
A fixed point theorem for mappings with a contractive iterate

THEOREM. Let (X, d) be a complete metric space, and f: X->X a continuous mapping satisfying the condition: there exists a k u for each xoE0X. LEMMA. If f: X)X be any mapping satisfying the condition of the above theorem then for each xEX, r(x) =sup,n d(fp(x), x) is finite. PROOF. Let xEX and let
NILPOTENT FINITE RINGS WITH PLANAR ZERO-DIVISOR GRAPHS

The zero-divisor graph Γ(R) of an associative ring R is the graph with all vertices non-zero zero-divisors (one-sided and two-sided) of R, and two distinct vertices x and y are joined by an edge iff xy = 0 or yx = 0 ([10]). In the present paper, we describe all nilpotent finite rings with planar zero-divisor graphs.
LONG MEMORY TESTING IN THE TIME DOMAIN

An integration test against fractional alternatives is suggested for univariate time series. The new test is a completely regression-based, lag augmented version of the Lagrange multiplier (LM) test by Robinson (1991, Journal of Econometrics 47, 67–84). Our main contributions, however, are the following. First, we let the short memory component follow a general linear process. Second, the innovations driving this process are martingale differences with eventual conditional heteroskedasticity that is accounted for by means of White's standard errors. Third, we assume the number of lags to grow with the sample size, thus approximating the general linear process. Under these assumptions, limiting normality of the test statistic is retained. The usefulness of the asymptotic results for finite samples is established in Monte Carlo experiments. In particular, several strategies of model selection are studied.An earlier version of this paper was presented at the URCT Conference in Faro, Portugal, 2005, and at the Econometrics Seminar of the University of Zürich. We are in particular grateful to Peter Robinson and Michael Wolf for helpful comments. Moreover, we thank two anonymous referees for reports that greatly helped to improve the paper.
The Thermoelasticity of Laser-Based Ultrasonics

ABSTRACT The generation of ultrasound by heat deposition due to laser irradiation has several advantages over conventional generation by piezoelectric transducers. Ultrasound generation by focused laser beam irradiation is a problem of thermoelastodynamics. A mathematical analysis for focused laser beam heating of the surface of an elastic half-space can be carried out by the use of integral transform techniques. It is, however, well known that a point source of heat is mechanically equivalent to a center of expansion. Here we use, therefore, simpler thermoelastic arguments to determine the mechanical loading equivalent to heating by laser irradiation, and then proceed to determine the induced wave motion. This approach has the advantage that the surface center of expansion can be determined for a general class of elastic materials without the necessity of using integral transform techniques. As an example, we consider line-focused laser irradiation of a transversely isotropic material whose axis of symmetry is perpendicular to the free surface of the body. General calculations of ultrasound generated by laser irradiation have shown that by far the most significant part of the generated surface motion is a pulse propagating with the velocity of Rayleigh surface waves. In the approach presented here, the surface-wave pulse is determined for time-harmonic excitation by the use of the reciprocity theorem, whereby the two reciprocal solutions are the actually generated surface waves and a “virtual” surface wave. The technique has general applicability for anisotropic and inhomogeneous materials, as long as the general form of the surface wave is known. Here we consider the case of a transversely isotropic material. In the last part, Fourier superposition of ultrasonic surface wave harmonics is used to obtain the surface wave pulse for arbitrary time dependence of the laser pulse.