Miracle-dz/UniFAR-FTUs huggingface dataset:
On the algorithms for the computation of even discrete cosine transform-2 (EDCT-2) of real sequences

An algorithm based on O/sup 2/DFT (odd-time odd-frequency discrete Fourier transform) is presented for the computation of the EDCT-2 of purely real sequences. Comparison of this algorithm with two others available in the literature shows that it is computationally superior for EDCT-2 evaluation of real sequences (N>8). Its computational advantage is based on its lesser real multiplication requirements. >
THE SPACE OF EXITS OF A MARKOV PROCESS

Martin's theory makes it possible to describe the sets of all non-negative harmonic and superharmonic functions in an arbitrary domain of euclidean space. To each Markov process there corresponds the class of so-called excessive functions, analogous in their properties to the class of non-negative superharmonic functions. The study of this class is closely connected with the study of the space of exits of a Markov process. Corresponding results for discrete Markov chains were obtained by Doob, Hunt and Watanabe, and for certain types of processes with variable time by Kunita and Watanabe. The paper gives an account of the general theory, which includes as particular cases all the results listed.
Large-Area Mapping at 850 Microns. I. Optimum Image Reconstruction from Chop Measurements

We present results on the optimum reconstruction of chop data taken using the Submillimeter Common-User Bolometer Array on the James Clerk Maxwell Telescope. Using an artificial data set with known noise properties, we analyze three techniques for constructing images of the sky from the chop data: Emerson Fourier deconvolution, matrix inversion, and maximum entropy reconstruction. We conclude that a matrix inversion formulation via an iterative procedure produces the best image reconstructions. We apply the three reconstruction techniques to produce maps of the calibration point source CRL 618 and the ρ Ophiuchi A core at 850 μm and use Wiener filtering to remove the high-frequency noise component from the matrix inversion method.
The Probability of Exceedance as a Nonparametric Person-Fit Statistic for Tests of Moderate Length

To classify an item score pattern as not fitting a nonparametric item response theory (NIRT) model, the probability of exceedance (PE) of an observed response vector x can be determined as the sum of the probabilities of all response vectors that are, at most, as likely as x, conditional on the test’s total score. Vector x is to be considered not fitting when its PE is smaller than a prespecified level. Although this concept is not new, it is hardly if ever applied in practice. In the present paper, the authors show how the PE of a response vector x can be computed in a NIRT context and how misfitting response patterns are detected using the exact distribution of PE. Results from two empirical applications are discussed. A simulation study is conducted to investigate the robustness of the PE against violation of the invariant item ordering condition. Finally, considerations over possible asymptotic distributions of PE are discussed.
Queueing Networks: A Survey of Their Random Processes

In this paper we review three topics in queueing network theory: queue length processes, sojourn times, and flow processes. In the discussion of the queue length processes we present results for the continuous-time process and several embedded processes. Then we compare continuous-time processes with embedded processes. In considerable generality we present results for mean sojourn times and discuss the distributions of sojourn times. In the discussion of flow processes we present results for various queueing systems. Our bibliography of over 300 references, while not exhaustive, does cover the major papers for the topics considered.
Thermally Driven MHD Dynamo in a Rotating Spherical Shell

In order to find a possible mechanism of the geodynamo the motion of an electrically conducting Boussinesq fluid which is driven by the thermal convection in a rotating spherical shell is investigated numerically. It is observed that the dynamo action can be effective when the Roberts number is below a critical value and that the polarity of the magnetic dipole moment changes chaotically in time. The intensification mechanism of the magnetic field the concentrate-and-stretch of the magnetic lines - is clarified at the first time by a detailed comparison of the spatial structures of the velocity and the magnetic fields.
Sequence IR images background estimation algorithm based on kernel exponential weighted least squares

Background estimation plays an essential role in many infrared (IR) target detection algorithms. A kernel-based background estimation algorithm for stationary camera is proposed in this paper. The nonlinear version of least squares (LS) algorithm: kernel least squares (KLS) and its exponential weighted form (KEWLS) are deduced use kernel methods (KMs). The background of IR image is estimated by KLS or KEWLS nonlinear regression utilize sequence images as training set; then targets are segmented by threshold dependent techniques in the difference image. Experiments of nonlinear function regression and IR image background estimation are performed. The results of these experiments are compared to that of LS algorithm, a single-frame and a multi-frame background estimation algorithm. The feasibility of nonlinear function regression and background estimation via kernelized LS is thus demonstrated.
A fast kernel tracking algorithm based on local gradient histograms

A common tracking algorithm solves several problems such as detection and localization of an object of interest in the scene, invariance to different movement directions of the object, occlusion of the target, when the target exits or reenters to the scene and so on. Nowadays the frame rates are various from 30 FPS (frames per second) to 300 FPS in special devices. Tracking algorithms can be classified as follows: point trackers, kernel trackers, and silhouette trackers. In this work, we propose a kernel tracking algorithm based on a local gradient histogram matching algorithm and prediction of the target position in video sequence frames.
Recognition of raised characters for automatic classification of rubber tires

The recognition of raised alphanumeric markings on rubber tires for their automatic classification is presented. Raised alphanumeric markings on rubber tires show different characteristics from those of printed characters. In the preprocessing step of the proposed method, we first determine the slope of an arc, along which alphanumerics are marked, using the Hough transform, and align them horizontally. Then we separate each character using vertical and horizontal projections. In the recognition step, to recognize characters hierarchically we use several effective features, such as width of a character, number of cross points, partial projections, and distance features. Computer simulation results show that the proposed system can be successfully applied to automatic classification of rubber tires.
Numerical simulation of topographically forced mesoscale variability in a well-mixed marine layer

Abstract A simple nonlinear numerical model of a well-mixed marine layer is used to study topographically forced mesoscale variability off coastal California. The model is used to simulate a persistent wind maximum observed near Point Conception during northwesterly winds. The model also demonstrates the development of a coastally trapped Kelvin wave and a marine-layer eddy when the large-scale forcing is suddenly reduced. The model is a one-layer, two-dimensional, gridpoint model with idealized coastal topography. The model assumes that potential temperature and wind are constant with height in the layer and that the layer is capped by an inversion. Effects of diabatic heating, water vapor, entrainment, and spatial variations of potential temperature are neglected in order to focus on topographic effects. The model solves for the two horizontal components of the marine-layer wind and the marine-layer height. A comparison of the model results with observations taken near Point Conception during the 1983 O.
Periodic orbits and nonintegrability of generalized classical Yang–Mills Hamiltonian systems

The averaging theory of first order is applied to study a generalized Yang–Mills system with two parameters. Two main results are proved. First, we provide sufficient conditions on the two parameters of the generalized system to guarantee the existence of continuous families of isolated periodic orbits parameterized by the energy, and these families are given up to first order in a small parameter. Second, we prove that for the nonintegrable classical Yang–Mills Hamiltonian systems, in the sense of Liouville–Arnold, which have the isolated periodic orbits found with averaging theory, cannot exist in any second first integral of class C1. This is important because most of the results about integrability deals with analytic or meromorphic integrals of motion.
Adaptive cancellation of microactuator resonance in hard disk drives

This article presents an adaptive resonance compensation scheme for microactuator-based dual-stage servo system in hard disk drives. The approach is to identify the microactuator resonant modes and compensate the model accordingly to a simpler one by pole-zero cancellation. Consequently, the servo controller can be designed based on the compensated fixed model despite actuator resonant mode variations. Simulation and experiment results show that this adaptive compensation scheme can suppress microactuator resonance without priori knowledge of the resonant modes. This approach makes the servo control system robust against microactuator resonance variations.
Inversion of broad frequency band geomagnetic response data.

Electromagnetic response data for the Earth covering a wide frequency span are analysed using linearised inverse theory. The response measure adopted is the natural logarithm of the complex apparent resistivity. Model finding and interpretation takes place in plane geometry, a simple transformation converts the solutions to spherical geometry for global problems. Thus the methods will apply to local problems, where the combination of AMT and MT data provides several decades of frequency, and to global problems of which this paper is an example. The global data used here are drawn from four sources and cover more than 6 decades in frequency (3.5×10-9 to 8.7×10-3Hz).
Size dependence of molecular fluorescence enhancement of nanoporous gold

We report molecular fluorescence enhancement of free-standing nanoporous gold with tunable nanopore size. The fluorescence intensity of indocynanine green adsorbed on human-serum-albumin-coated nanoporous gold films significantly increases with decreasing nanopore size. The large fluorescence enhancement results from the near-field enhanced excitation and radiative decay rate of fluorophore due to the strong electromagnetic fields produced by nanosized curvatures as well as the coupling between the neighbor gold ligaments.
ON THE RIEMANN-LIOUVILLE FRACTIONAL CALCULUS AND SOME RECENT APPLICATIONS

When Benoit Mandelbrot discussed the problem of fractional Brownian motion in his classic book The Fractal Geometry of Nature, he already pointed out some strong relations to the Riemann-Liouville fractional integral and differential calculus. Over the last decade several papers have appeared in which integer-order, standard differential equations modeling processes of relaxation, oscillation, diffusion and wave propagation are generalized to fractional order differential equations. The basic idea behind all that is that the order of differentiation need not be an integer but a fractional number (i.e. dq/dtq with 0<q<1). Applications to slow relaxation processes in complex systems like polymers or even biological tissue and to self-similar protein dynamics will be discussed. In addition, we investigate a fractional diffusion equation and we present the corresponding probability density function for the location of a random walker on a fractal object. Fox-functions play a dominant part.
A Note on Guggenheim's Theory of Strictly Regular Binary Liquid Mixtures

This note attempts to revise and extend the formulae proposed by Guggenheim (1935) in his theory of a special (hypothetical) type of liquid mixture which, in the account of Guggenheim’s paper given by Fowler (1936), is called strictly regular. According to the definitions in these sources a binary liquid mixture is said to be strictly regular if (i) there is no volume change on mixing, whatever the relative amounts of the two components, (ii) it possesses a definite co-ordination number, г say, so that each molecule, of either kind, in the liquid has precisely г (nearest) neighbours.
Short-time Lyapunov exponent analysis and the transition to chaos in Taylor–Couette flow

Short-time Lyapunov exponent analysis is a new approach to the study of the stability properties of unsteady flows. At any instant in time the Lyapunov perturbations are the set of infinitesimal perturbations to a system state that will grow the fastest in the long term. Knowledge of these perturbations can allow one to determine the instability mechanisms producing chaos in the system. This new method should prove useful in a wide variety of chaotic flows. Here it is used to elucidate the physical mechanism driving weakly chaotic Taylor–Couette flow. Three-dimensional, direct numerical simulations of axially periodic Taylor–Couette flow are used to study the transition from quasi-periodicity to chaos. A partial Lyapunov exponent spectrum for the flow is computed by simultaneously advancing the full solution and a set of perturbations. The axial wavelength and the particular quasi-periodic state are chosen to correspond to the most complete experimental studies of this transition. The computational results are consistent with available experimental data, both for the flow characteristics in the quasi-periodic regime and for the Reynolds number at which transition to chaos is observed. The dimension of the chaotic attractor near onset is estimated from the Lyapunov exponent spectrum using the Kaplan–Yorke conjecture. This dimension estimate supports the experimental observation of low-dimensional chaos, but the dimension increases more rapidly away from the transition than is observed in experiments. Reasons for this disparity are given. Short-time Lyapunov exponent analysis is used to show that the chaotic state studied here is caused by a Kelvin–Helmholtz-type instability of the outflow boundary jet of the Taylor vortices.
The turbulent concentration field of a methane jet

Detailed measurements of turbulent concentration parameters in a round free methane jet up to 70 diameters downstream from the jet source are described. The concentration changes were obtained using a Raman spectrometer designed for the measurement of a methane vibrational transition function, and processed using a photon correlator. Mean and fluctuating concentration levels are given, together with the concentration probability density distribution. A theory for interpreting the statistical aspects of the signal is presented and results are compared with other data from the literature on jets of uniform and non-uniform density. It is shown that the intensity of concentration fluctuations has an asymptotic value of 28·5% in the far field region of the jet. One interesting feature of the data is the deviation from Gaussian statistics along the jet centre-line.
An extended finite element formulation for contact in multi‐material arbitrary Lagrangian–Eulerian calculations

Multi‐material Eulerian and arbitrary Lagrangian–Eulerian methods were originally developed for solving hypervelocity impact problems, but they are attractive for solving a broad range of problems having large deformations, the evolution of new free surfaces, and chemical reactions. The contact, separation, and slip between two surfaces have traditionally been addressed by the mixture theory, however the accuracy of this approach is severely limited. To improve the accuracy, an extended finite element formulation is developed and example calculations are presented. As a side benefit, the mixture theory is eliminated from the multi‐material formulation, eliminating the issues associated with the equilibration time between adjacent materials. By design, the new formulation is relatively simple to implement in existing multi‐material codes, parallelizes without difficulty, and has a low memory burden. Copyright © 2006 John Wiley & Sons, Ltd.
A note on the Carleson measure characterization of BMOA functions on the unit ball

An equivalent form of the well-known Carleson measure condition that characterizes BMOA functions on the unit ball is given. As an application, it is proved that the Toeplitz operator T^, <p e H°° (S), is bounded on the Hardy-Sobolev space H^ , 0 < a < oo .
Evolution of the ferromagnetic resonance spectrum of a hexagonal antidot lattice with film thickness: Experiment and numerical simulations

Experimental and theoretical studies of the evolution of the ferromagnetic resonance spectrum with film thickness for hexagonal lattice of antidots have been reported. We found three different quasi-uniform modes in the resonance spectrum. Calculations of the local dynamic susceptibility tensor show that these modes are related to the resonances from quasiuniformly magnetized regions of the hexagonal antidot array unit cell. The increase of the film thickness results in the broadening of the resonance lines as well as the appearance of additional resonance lines. Good qualitative correlation of the theory and experiment was obtained. Additional relaxation mechanisms due to magnetic inhomogeneities are also discussed.
Calibrating a solar x-ray telescope using the Crab Nebula

The Crab Nebula (see Figure 1) has been used to calibrate xray detectors on many satellite-, rocket-, and balloon-borne missions. It provides a bright and stable broadband source with a well-characterized spectrum. For space-based telescopes, in particular, this allows adjusting to changes over time in filters, electronics, optics, and other sensors. We demonstrate here the feasibility of extending this calibration practice to the Solar XRay Imager (SXI-N) telescope aboard a Geostationary Operational Environmental Satellites (GOES) mission launched in May 2006. The primary mission of the GOES series, which is operated by the National Oceanic and Atmospheric Administration (NOAA), is to monitor weather on Earth. SXI’s purpose is to provide real-time images of the sun and solar corona between 6 and 60A, which helps space weather forecasters by providing longterm solar climatological observations. Previous SXI instruments were not calibrated. They suffer from ongoing filter and electronic unit degradation, and a consequent degree of measurement uncertainty. Onboard x-ray calibration of satellite instruments is not generally practical because the required sources would be too large. NOAA’s current plan for calibrating SXI-N would use expensive sounding-rocket underflights to make solar observations simultaneously with the GOES. In-flight x-ray calibrations using the Crab Nebula may not have been considered in these cases because of the nebula’s low flux compared with that of the solar phenomena being measured. To evaluate the feasibility of this approach, we used existing Crab Nebula measurements from the Einstein Observatory, shown in Figure 2, to see whether SXI-N observations could achieve a signal-to-noise ratio (SNR) of at least 5, which would meet the instrument’s 20% photometric requirement. We also modeled likely noise sources that would enter into our signalto-noise calculations. Figure 1. The Crab Nebula, shown at visible wavelengths. Courtesy of NASA and ESA (Hubble WFPC2), and Allison Loll and Jeff Hester (Arizona State University).
Control and elimination of nucleation-related defects in GaP/Si(001) heteroepitaxy

GaP films were grown on offcut Si(001) substrates using migration enhanced epitaxy nucleation followed by molecular beam epitaxy, with the intent of controlling and eliminating the formation of heterovalent (III-V/IV) nucleation-related defects—antiphase domains, stacking faults, and microtwins. Analysis of these films via reflection high-energy electron diffraction, atomic force microscopy, and both cross-sectional and plan-view transmission electron microscopies indicate high-quality GaP layers on Si that portend a virtual GaP substrate technology, in which the aforementioned extended defects are simultaneously eliminated. The only prevalent remaining defects are the expected misfit dislocations due to the GaP–Si lattice mismatch.
Buckling and postbuckling of spherical shells with apical cutout under ring load

The buckling and postbuckling behavior of elastoplastic spherical shells with circular apical cutout under a ring load was investigated analytically and experimentally. A finite element code based on the updated Lagrangian formulation was established to analyze this buckling problem by considering nonlinear geometric and material properties. An iterative scheme controlled by displacement was adopted in the solution procedure to avoid numerical instability near the limit buckling load. Ring loads of both line and strip types were analyzed. A testing device was used to perform buckling experiments. The ratio of diameter to thickness of the steel specimens was between 30.23 and 86.75. The influence of the ratio of diameter to thickness and the sizes of the apical cutout and ring load on the limit buckling load are discussed. The analytical results agree satisfactorily with experimental ones for medium-carbon steel spherical shells. Convex and concave modes of postbuckling deformation around the apex are obtained in analysis and observed in experiment for varied combinations of the sizes of ring load and apical cutout and ratio of diameter to thickness of the spherical shells.
Planet formation from planetesimals and diversity of planetary systems

Here, gravitational scattering of planetesimals (viscous stirring and dynamical friction) and their growth through pairwise collisions (runaway/oligarchic growth) are explained in detail. The masses of accreted protoplanets depend on initial disk surface density and semimajor axis. When the mass of a protoplanet becomes larger than a critical value that is a few to ten earth masses, runaway gas accretion from the disk onto the planet starts. The dependence of the protoplanet masses is responsible for the diversity of extrasolar planetary systems, although orbital migrations of planets are also important drivers to produce the diversity.
Molecular outflows associated with young stellar objects in the L1641 region of Orion

The results of a follow-up survey of a flux-limited sample of IRAS sources located in the L1641 region south of the Orion Nebula are presented. The molecular outflow sources identified include all previously known molecular outflows and, reported for the first time, three additional molecular outflows. None of the observed molecular outflows appear to be oriented along a preferred direction, and they are also distributed nonuniformly throughout the L1641 region. Maps of the molecular outflows suggest that the direction of the molecular outflow may be shaped by the ambient molecular cloud. The estimated momentum of the observed molecular outflows is found to be sufficient to support the molecular cloud over the dissipation time scale against gravitational collapse. 31 refs.
Light-cone effect and relaxation after a quantum quench from excited states in the Ising chain

The time evolution and stationary behaviour of local observables is studied after a quantum quench of the magnetic field in the transverse field Ising chain, when the initial state is chosen as an excited state of the pre-quench Hamiltonian. Relaxation to the Generalized Gibbs Ensemble is proved. Equal-time longitudinal two point function and entanglement entropy are analytically derived for a class of excited states which confirm the light-cone spreading of correlations also starting from excited states.