The Taylor series method for the problem of the rotational motion of a rigid satellite

This paper presents the Taylor series method for integration of differential equations describing the rotational motion of a rigid satellite. We compared the presented algorithm with other methods, and we show that it gives the most accurate results with reasonable efficiency.     

Solutions homoclinic to regular precessions of a symmetric satellite

The aim of this paper is to study numerically asymptotic manifolds and homoclinic solutions to the regular precessions of a rigid symmetric satellite in a circular orbit.     

A New Interlaboratory Characterisation of Silicon,Rare Earth Elements and Twenty‐Two Other Trace Element Concentrations in the Natural River Water Certified Reference Material SLRS‐6 (NRC‐CNRC)

The natural river water reference material SLRS‐6 (NRC‐CNRC) is the newest batch of a quality control material routinely used in many international environmental laboratories. This work presents a nine‐laboratory compilation of measurements of major and trace element concentrations and their related uncertainties, unavailable in the NRC‐CNRC certificate (B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Y, Zr and REEs). Measurements were mostly made using inductively coupled plasma‐mass spectrometry. The results are compared with equivalent data for the last batch of the material, SLRS‐5, measured simultaneously with SLRS‐6 in this study. In general, very low concentrations, close to the quantification limits, were found in the new batch. The Sr isotopic ratio is also reported.     

Polarization of synchrotron emission from relativistic reconfinement shocks

We study the polarization properties of relativistic reconfinement shocks with chaotic magnetic fields. Using our hydrodynamical model of their structure, we calculate synthetic polarization maps, longitudinal polarization profiles and discuss the spatially averaged polarization degree as a function of jet half-opening angle  Θ _j   , jet Lorentz factor  Γ _j   and observer inclination angle to the jet axis  θ_obs  . We find that for  θ_obs≲Θ _j   the wave electric vectors are parallel in the vicinity of the structure ends and perpendicular in between, while for  θ_obs > Θ _j   the polarization can only be perpendicular. The spatially averaged polarization degree does not exceed 30 per cent. Parallel average polarization, with polarization degrees lower than 10 per cent, has been found for  θ_obs < Θ _j   under the condition  Γ _j Θ _j > 1  . As earlier works predicted the parallel polarization from relativistic conical shocks, we explain our results by discussing conical shocks with divergent upstream flow.     

Multi-resolution clustering analysis and 3-D visualization of multitudinous synthetic earthquakes

We use modern and novel techniques to study the problems associated with detection and analysis of multitudinous seismic events, which form the background for isolated great earthquakes. This new approach involves multivariate analysis of low and large magnitude events recorded in space over a couple of centuries in time. We propose here the deployment of the clustering scheme both for extracting small local structures and large-scale trends in synthetic data obtained from four numerically simulated models with: uniform properties (U), a Parkfield-type asperity (A), fractal brittle properties (F), and multi-size-heterogeneity fault zone (M). The mutual nearest neighbor (mnn) clustering scheme allows for extraction of multi-resolutional seismic anomalies in both the spatio-temporal and multi-dimensional feature space. We demonstrate that the large earthquakes are correlated with a certain pathway of smaller events. Visualization of the anomalies by using a recently introduced visualization package Amira reveals clearly the spatio-temporal relationships between clusters of small, medium and large earthquakes, indicating significant stress relaxation across the entire fault region. We demonstrate that this mnn scheme can extract distinct clusters of the smallest events, which precede and follow a singularly large magnitude earthquake. These clusters form larger spatio-temporal structures comprising a series of large earthquakes. The link between the large and medium magnitude events is not so clearly understood. Short-ranged correlations are dominated by strong spatio-temporal anomalies, thus reflecting the global seismic properties of the entire fault zone.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Analysis of a group of seismic events using rotational components

Analysis of a group of seismic events which took place in central Italy and have been recorded at the l’Aquila Observatory reveals proportionality between the maximum seismic signal (the displacement velocity) and the maximum amplitudes of rotational components. To compare the seismic events in the aspect of energy emitted as rotational motions, the rotation indices are used; these indices help us also to differentiate between the results obtained for different frequency spectra. In the adopted higher frequency range, 2.6–43 Hz, the relation between maximum displacement velocities and the rotation indices is roughly reciprocal, while for the lower frequencies, 0.3–3 Hz, there is no clear relationship. The share of rotation motions in the whole seismic energy emitted from the source varies during the seismic event. Research on the rotational components hidden in the seismic field gives a new insight into the processes in the source.