Miracle-dz/UniFAR-FTUs huggingface dataset:
A refined convergence analysis of multigrid algorithms for elliptic equations

Multigrid algorithms, in particular, multigrid V-cycles, are investigated in this paper. We establish a general theory for convergence of the multigrid algorithm under certain approximation conditions and smoothing conditions. Our smoothing conditions are satisfied by commonly used smoothing operators including the standard Gauss–Seidel method. Our approximation conditions are verified for finite element approximation to numerical solutions of elliptic partial differential equations without any requirement of additional regularity of the solution. Our convergence analysis of multigrid algorithms can be applied to a wide range of problems. Numerical examples are also provided to illustrate the general theory.
Adapting Marchal's test of escape to real triple stars

Context. For a general N-body system, Marchal constructed an analytical test of escape, which uses only a one-dimensional projected motion state of the system at any given instant. This test is well adapted to identifying real, disintegrating small stellar systems, of which the full motion states are generally unavailable. However, to our knowledge, there has been no practical application of this test until the present-day.
Self-similar evolution of astrophysical and laboratory jets: expansion and collimation

In this paper, we deal theoretically with expansion, collimation or collapse of radiating fluids and jets, especially. Firstly, we consider a case in which radiation can be neglected in the modeling. Secondly, radiative losses are introduced. Finally, we compare, on the one hand, hydrodynamics self-similar solutions to laboratory jet experiments and, on the other hand, self-similiar solutions with radiation losses to numerical simulations.
Nonlinear hydrodynamic and real fluid effects on wave energy converters

Ocean wave energy has been of interest since at least the mid-1970s and great advances in the understanding of the fundamental principles of wave energy extraction and converter modelling have been made using linear hydrodynamic analysis. This paper reviews efforts that have been made to use nonlinear hydrodynamics to analyse wave energy converter behaviour and performance. Both ‘partially nonlinear’ and fully nonlinear potential flow methods, as well as computational fluid dynamics methods solving the Navier–Stokes equations and smoothed particle hydrodynamics have been used for this purpose and are reviewed here. These more complex methods have been applied primarily to single devices, so array and mooring line interactions are not considered. While a number of studies have been performed in these areas and results are encouraging, further advances are required to give accurate prediction or reproduction of experimental results.
AEROELASTICITY AND FLIGHT MECHANICS: STABILITY ANALYSIS USING LAPLACE-DOMAIN AERODYNAMICS

An efficient method for the non-iterative solution of the nonlinear flutter eigenvalue problem is presented. The properties of the piecewise quadratic decomposition employed make it particularly suitable for the parallel solution of aeroelastic stability problems where interaction of rigid-body and elastic motion is of interest or where the flutter damping must be obtained with accuracy, e.g. when comparison to flutter flight testing is intended. Additionally, the method allows the use of Laplace-domain aerodynamics if available. The paper presents a realistically complex test case which exposes some of the advantages and current shortcoming of the proposed solution procedure.
Analysis of repeated measurements in physical therapy research: multiple comparisons amongst level means and multi-factorial designs

Abstract This paper follows on from the previous article published in Physical Therapy in Sport (PtiS) on the analysis of repeated measurements (2). The aims are (i) to discuss more formal methods of making multiple comparisons amongst level means in a single factor and (ii) to describe the analysis of more complicated designs in physical therapy research, which may involve more than one factor of interest. Issues are discussed in parallel with the options for analysis that are available in the Statistical Package for the Social Sciences (SPSS). First, it is outlined how the hypothesis of interest and nature of the factor of interest (ordinal or nominal) governs how many multiple comparisons are made and whether multiple comparisons are needed at all. Next, it is explained why the sphericity assumption is just as important for making accurate multiple comparisons amongst level means as it is for the accuracy of the omnibus hypothesis test on the factor of interest. Using the results of statistical simulations, the relative merits of the different methods that are available for making multiple comparisons are then discussed. Next, the general problem that is associated with most multiple comparison procedures; relatively low statistical power, is highlighted and new step-wise correction procedures that are designed to overcome this problem of low power are introduced. Finally, the analysis and presentation of results for multifactorial designs is covered, including an explanation of what is considered to be the most complicated aspect of such analyses; the interpretation of a significant ‘interaction' between factors.
An adaptive strategy based on linear prediction of queue length to minimize congestion in Barabási—Albert scale-free networks

In this paper, we propose an adaptive strategy based on the linear prediction of queue length to minimize congestion in Barabási—Albert (BA) scale-free networks. This strategy uses local knowledge of traffic conditions and allows nodes to be able to self-coordinate their accepting probability to the incoming packets. We show that the strategy can delay remarkably the onset of congestion and systems avoiding the congestion can benefit from hierarchical organization of accepting rates of nodes. Furthermore, with the increase of prediction orders, we achieve larger values for the critical load together with a smooth transition from free-flow to congestion.
Overview of ETC program in Korea

Electromagnetic launcher (EML) technology had been investigated in South Korea since 1989. Muzzle velocities up to 4.3 km/sec were obtained using 1.3 g projectiles in 1991. Since 1992, the Korea Program has concentrated on electrothermochemical (ETC) technology instead of EML technology. A 20 mm caliber ETC gun was designed and set up together with the pulse-forming network of a capacitor bank. A 107 g projectile was accelerated to up to 1.24 km/sec. The new Korea ETC program is established to investigate ETC launchers, compulsators, power switches, etc. The whole program will be performed by the Agency for Defense Development with the help of some Korean institutes and industries.
Commissioning and operation of the Brazilian Synchrotron Light Source

The Brazilian National Synchrotron Light Laboratory, LNLS, operates a 1.37 GeV electron storage ring with a 120 MeV injector linac. Commissioning of the storage ring at low energy started on May 1996 and now, an year later, we can store 120 mA at 120 MeV and ramp more than 75 mA to 1.37 GeV. A summary of the latest commissioning results and a description of the present operational performance of the LNLS Synchrotron Light Source facility is presented.
Genetic algorithms and neural networks generalizing the Jiles-Atherton model of static hysteresis for dynamic loops

This paper presents a method based on genetic algorithms and neural networks suitable for finding the five parameters of the Jiles-Atherton (JA) model for generalization to dynamic hysteresis loops. The aim is to obtain an equivalent static model for dynamic loops by updating its parameters varying the frequency of the imposed magnetic field H(t). Validations of the present approach compared to other numerical approaches, based on adding frequency-dependent losses to the static model, and versus experimental tests will be shown.
Vegetation extraction from IKONOS imagery using high spatial resolution index

In vegetation change monitoring and urban planning, the measurement and mapping of the green vegetation over the Earth play an important role. The normalized difference vegetation index (NDVI) is the most popular measure to generate vegetation maps which resolution depends on that of the input images. High-resolution imagery can lead to better vegetation classification accuracy. Various methods are proposed to provide high spatial resolution vegetation indices based on a fusion concept. IKONOS produces high spatial resolution panchromatic (Pan) images and moderate spatial resolution multispectral (MS) images. Generally, for an image fusion purpose, the conventional bi-cubic interpolation scheme is used to resize MS images. Nevertheless, this scheme fails around edges and consequently produces blurred edges and annoying artifacts in interpolated MS images. To avoid this problem, an artifact-free image interpolation method is proposed. This study presents a modified NDVI that provides high spatial resolution maps which differentiate vegetated surfaces from other surfaces when using IKONOS imagery. This vegetation index (HRNDVI: high resolution NDVI) is based on a newly derived formula including high spatial resolution information from IKONOS. The HRNDVI is computed based on the resampled MS images and the Pan images. The proposed vegetation index takes advantage of both the high spatial resolution information of Pan images and the robustness of the interpolation technique. Visual and quantitative analysis demonstrates that this index appears promising and performs well in vegetation extraction and visualization.
Influence functions and outlier detection under the common principal components model: A robust approach

The common principal components model for several groups of multivariate observations assumes equal principal axes but different variances along these axes among the groups. Influence functions for plug-in and projection-pursuit estimates under a common principal component model are obtained. Asymptotic variances are derived from them. Outlier detection is possible using partial influence functions. Copyright Biometrika Trust 2002, Oxford University Press.
Periodic Time Series Models

This book considers periodic time series models for seasonal data, characterized by parameters that differ across the seasons, and focuses on their usefulness for out-of-sample forecasting. Providing an up-to-date survey of the recent developments in periodic time series, the book presents a large number of empirical results. The first part of the book deals with model selection, diagnostic checking and forecasting of univariate periodic autoregressive models. Tests for periodic integration, are discussed, and an extensive discussion of the role of deterministic regressors in testing for periodic integration and in forecasting is provided. The second part discusses multivariate periodic autoregressive models. It provides an overview of periodic cointegration models, as these are the most relevant. This overview contains single-equation type tests and a full-system approach based on generalized method of moments. All methods are illustrated with extensive examples, and the book will be of interest to advanced graduate students and researchers in econometrics, as well as practitioners looking for an understanding of how to approach seasonal data.
A neural piecewise linear classifier for pattern classification

A neural piecewise linear classifier, based on the Kohonen learning vector quantization (LVQ2) and the Kohonen self-organizing feature map is proposed. The classifier has two stages and a feedback loop. In the first stage, the Kohonen self-organizing feature map network is used to find the approximate position of the prototype vectors for each class. In the second stage, the Kohonen LVQ2 supervised learning algorithm is used to fine-tune the position of the approximate prototype vectors. The accuracy of the classifier is improved by adding an adaptive feedback scheme. Depending on the intrinsic complexity of the class distribution and overall partitioning of the space, the neural classifier automatically increases the number of neurons, improving the error performance. The classifier was tested on a set of high-dimensional real data obtained from ship images. The performance is compared with a piecewise linear tree classifier and a neural classifier. <<ETX>>
Mobile Robot Monte Carlo Localization Based on Improved Local Invariant Feature Extraction Algorithm

To deal with the localization problem of robot equipped with monocular camera, a novel Monte Carlo method based on improved Scale Invariant Feature Transform (SIFT) is proposed. Firstly, the steps of constructing scale space, detecting extrema and confirming keypoints are employed to create the key feature points. Secondly, each keypoint is described by the rotation invariant Texture patterns, which are computed from the image patch centered at the keypoint, and be combined to SIFT feature to construct the union feature. Finally, a rotation invariant textured SIFT descriptor is formed. During robot motion, the information from feature observations is fused with that from the odometry by particle filter, which effectively improves the speed and accuracy of the localization. Experimental results demonstrate the validity of the approach.
Revisiting activity sampling: a fresh look at binomial proportion confidence intervals

The Wald interval is typically used to assign confidence to the accuracy of activity sampling studies. It is known the performance of the Wald interval is poor, especially when the observed probability is near zero or one. The suitability of the Wald interval for activity sampling is not often discussed in the operations management literature; if it is, this is usually followed by inappropriate and incorrect advice. Herein, a range of alternative binominal confidence intervals for activity sampling is reviewed. A number of selection criteria are considered including achievement of the target nominal coverage probability, size of the interval, and ease of use and presentation. It is recommended that the Clopper-Pearson interval is used for activity sampling. A table of confidence intervals and sample sizes that is specifically designed to be used within a new activity sampling procedure based on the Clopper-Pearson interval is developed. Finally, pedagogical issues are considered. [Received 20 October 2009; Revised 17 August 2015; Accepted 20 May 2016]
TRANSFER ENTROPY ESTIMATION SUPPLEMENTS TIME-DOMAIN BEAT-TO-BEAT BAROREFLEX SENSITIVITY INDEX UNDER POSTURAL STRESS

Baroreflex mechanism plays a vital role in cardiovascular regulation by contributing in sympathetic-vagal imbalance triggered by baroreceptor reflex. This study estimates BRS (Baroreflex Sensitivity) index from beat-to-beat systolic blood pressure (SBP) and RR interval (RRi) series using time-domain windowed cross-correlation method. This index is supplemented by an information domain technique called Transfer Entropy (TE) is applied to decipher the directional coupling between SBP and RRi series. The study is performed on EUROBAVAR data. The results show that BRS index calculated is large (1.157±0.533) in supine position which supplemented by TE (SBP-RR) of (0.129±0.09) as compared to standing position for which BRS index is (0.866±0.472) and a TE (SBP-RR) of (0.04±0.03) for EUROBAVAR data with a p-value<0.05. Also, it is found that both the TE indices i.e. from SBP to RR and from RR to SBP show correlated results with the time domain BRS index in both supine and standing positions. Further, the cases with possible BRS failure are having very small values of BRS index, which are not assigned any value by prevalent methods. This shift is absent in BRS failure patients which is supplanted by TE (RR-SBP) sharing more information bits than TE (SBP-RR). Further, it is observed that patients having baroreflex impairment show reversal of information flow which is indicated by a larger TE (RRSBP) index as compare to TE (SBP-RR) index. Time domain BRS index lacks directional information which is provided by TE and hence this supplemental information gives better interpretation of BRS index especially in patients having suppressed baroreflex. Index Terms: Baroreflex sensitivity, Directional coupling, Cross-correlation, and Transfer entropy
Dust ion-acoustic shocks and holes

Properties of dust ion-acoustic (DIA) shocks and DIA holes are examined, assuming that a dusty plasma contains immobile charged dust grains, warm electrons, and warm ions. A Kortweg-deVries- Burgers equation for DIA shocks is derived by employing the hydrodynamic equations for the warm ion fluid and the Boltzmann electron density distribution. On the other hand, DIA holes arise when the warm ions follow a trapped vortex distribution. The profiles of DIA shocks and DIA holes are discussed. The results are useful for understanding the salient features of DIA shocks and holes that are recently observed in laboratory dusty plasma devices.
Suppression of the relaxation oscillation in the modulated output of semiconductor lasers

Practical rates of direct pulse modulation of semiconductor lasers have so far been limited to below several hundred megahertz, owing to serious distortion in the output signal caused by the relaxation oscillation of the light intensity. Based on theoretical analysis of the dynamic properties of lasing under constant injection of external radiation into the cavity modes, light injection is proposed as a method for suppressing the relaxation oscillation. The effectiveness of this method has been confirmed in a series of preliminary experiments which employed GaAs injection lasers both as the modulated laser and as the external source of the injected radiation.
The Chemical Composition of Exoplanet-hosting Binary Star Systems

A significant portion of stars occur as binary systems, in which two stellar components orbit a common center of mass. As the number of known exoplanet systems continues to grow, some binary systems are now known to harbor planets around one or both stellar components. As a first look into composition of these planetary systems, I investigate the chemical compositions of 4 binary star systems, each of which is known to contain at least one planet. Stars are known to vary significantly in their composition, and their overall metallicity (represented by iron abundance, [Fe/H]) has been shown to correlate with the likelihood of hosting a planetary system. Furthermore, the detailed chemical composition of a system can give insight into the possible properties of the system’s known exoplanets. Using high-resolution spectra, I quantify the abundances of up to 28 elements in each stellar component of the binary systems 16 Cyg, 83 Leo, HD 109749, and HD 195019. A direct comparison is made between each star and its binary companion to give a differential composition for each system. For each star, a comparison of elemental abundance vs. condensation temperature is made, which may be a good diagnostic of refractory-rich terrestrial planets in a system. The elemental ratios C/O and Mg/Si, crucial in determining the atmospheric composition and mineralogy of planets, are calculated and discussed for each star. Finally, the compositions and diagnostics of each binary system are discussed in terms of the known planetary and stellar parameters for each system.
The age structure of globular cluster systems in early-type galaxies and its dependence on host galaxy properties

Aims. We present the results of an optical – near-infrared photometric survey of globular cluster systems in early-type galaxies. Our project aims to study correlations between the age structure of the globular cluster systems and environmental as well as structural parameters of their host galaxies. Methods. To derive the age structure in globular cluster systems we use combined optical and near-infrared photometry. This combination facilitates the detection of young globular cluster sub-populations if their age differs significantly from the old (∼13 Gyr) population, i.e. if their age is <7 Gyr. We investigate globular cluster systems in galaxies located in the central regions of galaxy clusters (NGC 1399, M 87, NGC 4478), galaxies which are members of (sub-) groups (NGC 4365, NGC 5846) and isolated galaxies (NGC 3115 and NGC 7192). Further, we look for correlations between globular cluster system properties and structural parameters of the galaxies (velocity dispersion σ, color ((V − K), (B − V)), and luminosity MV ). For a quantitative analysis we define the “Methuselah” parameter, Mth – based on the fraction of young and old metal-rich globular clusters weighted by age, characterizing the age structure of a globular cluster system. Results. We find that, within our galaxy sample, group galaxies appear to host an intermediate-age globular cluster population, whereas the globular cluster systems in cluster galaxies and in rather isolated galaxies are dominated by an old globular cluster population. A weak correlation of Mth with the Hβ index of the integrated light of the host galaxies is the only trend found with respect to internal galaxy parameters.
A 327 MHz VLBI study of high redshift radio galaxies 1345+245, 1809+407 and 2349+289

Three high redshift radio galaxies, 1345+245 (4C 24.28, $z=2.889$), 1809+407 (4C 40.36, $z=2.267$) and 2349+289 (4C 28.58, $z=2.905$) were observed with VLBI at 327 MHz giving an angular resolution of $\simeq$40–100 mas and yielding images with the off-source noise level of 3$\sigma \simeq 3.5$ mJy/beam. On the centiarcsecond scale, the three sources are each characterized by two components with asymmetry both in flux density and in size. The compact components in the VLBI maps correspond to the hot spots in the VLA maps. No radio cores have been detected. The physical parameters for the components derived are consistent with a model in which shocks accelerate electrons in the hotspots.
Finite element analysis of direct thrust-controlled linear induction motor

This paper describes the finite element analysis of a direct thrust-controlled linear induction motor (LIM). The time-stepping finite element method and the moving mesh technique are used to calculate the dynamic characteristics of the LIM during direct thrust control. Because the LIM has an end effect, a thrust correction coefficient is introduced to predict actual thrust in control. The simulation results, the thrust and the stator flux linkage are shown and the stator current is compared experiments.
Invariant circles in the Bogdanov-Takens bifurcation for diffeomorphisms

Abstract We study a generic, real analytic unfolding of a planar diffeomorphism having a fixed point with unipotent linear part. In the analogue for vector fields an open parameter domain is known to exist, with a unique limit cycle. This domain is bounded by curves corresponding to a Hopf bifurcation and to a homoclinic connection. In the present case of analytic diffeomorphisms, a similar domain is shown to exist, with a normally hyperbolic invariant circle. It follows that all the ‘interesting’ dynamics, concerning the destruction of the invariant circle and the transition to trivial dynamics by the creation and death of homoclinic points, takes place in an exponentially small part of the parameter-plane. Partial results were stated in [5]. Related numerical results appeared in [16].