A semi-implicit numerical method for treating the time transient gas lubrication equation

Numerical method for treating time transient gas lubrication equatio

Strong earthquakes included «by chance» in Italian catalogues: single cases or a hint of more?

In principle, a few of the strong earthquakes (I0 >= 8/9, M >= 5.8) that affected Italy in the past may still be missing from parametric catalogues or be listed there as lesser events, their actual strength unrealized. This seems a reasonable enough inference, given that some strong earthquakes were listed by catalogues quite by chance, from information drawn, mainly or even solely, from a single source. Had this source been destroyed before catalogue compilers were able to consider it, or had they for any reason overlooked it, the earthquake it recorded could also have been missed or underestimated. This paper examines the two most peculiar Italian cases of «single- source earthquakes» (1561 «Vallo di Diano?»; 1639 «Amatrice?»). Is all relevant information on each event really tied up in a single source? And if so, why? Finally, are these cases unique or do they share any common features that could, by occurring elsewhere, act as markers for situations where forgotten earthquakes could still lurk undetected

Strong earthquakes included «by chance» in Italian catalogues: single cases or a hint of more?

In principle, a few of the strong earthquakes (I0 >= 8/9, M >= 5.8) that affected Italy in the past may still be missing from parametric catalogues or be listed there as lesser events, their actual strength unrealized. This seems a reasonable enough inference, given that some strong earthquakes were listed by catalogues quite by chance, from information drawn, mainly or even solely, from a single source. Had this source been destroyed before catalogue compilers were able to consider it, or had they for any reason overlooked it, the earthquake it recorded could also have been missed or underestimated. This paper examines the two most peculiar Italian cases of «single- source earthquakes» (1561 «Vallo di Diano?»; 1639 «Amatrice?»). Is all relevant information on each event really tied up in a single source? And if so, why? Finally, are these cases unique or do they share any common features that could, by occurring elsewhere, act as markers for situations where forgotten earthquakes could still lurk undetected

Upper body balance control strategy during continuous 3D postural perturbation in young adults

We explored how changes in vision and perturbation frequency impacted upright postural control in healthy adults exposed to continuous multiaxial support-surface perturbation. Ten subjects were asked to maintain equilibrium in standing stance with eyes open (EO) and eyes closed (EC) during sinusoidal 3D rotations at 0.25 (L) and 0.50 Hz (H). We measured upper-body kinematics – head, trunk, and pelvis – and analyzed differences in horizontal displacements and roll, pitch, and yaw sways. The presence of vision significantly decreased upper-body displacements in the horizontal plane, especially at the head level, while in EC the head was the most unstable segment. H trials produced a greater segment stabilization compared to L ones in EO and EC. Analysis of sways showed that in EO participants stabilized their posture by reducing the variability of trunk angles; in H trials a sway decrease for the examined segments was observed in the yaw plane and, for the pelvis only, in the pitch plane. Our results suggest that, during continuous multiaxial perturbations, visual information induced: (i) in L condition, a continuous reconfiguration of multi-body-segments orientation to follow the perturbation; (ii) in H condition, a compensation for the ongoing perturbation. These findings were not confirmed in EC where the same strategy – that is, the use of the pelvis as a reference frame for the body balance was adopted both in L and H

In Troubled Times, in a Divided Country: The 1789 Valtiberina Earthquake

The Valtiberina region (central Italy) has a seismic record going back to the Middle Ages and including five Io > VIII MCS earthquakes, the earliest of which (1352, 1389, 1458). though recently and extensively studied, remain rather poorly known. This makes it all the more important to ensure that the later ones (1789, 1917) are as throughly studied as possible. The 1789 earthquake is listed by the current Italian catalogue (CPTI Working Group 2004) with Io VIII-IX MCS and Mm 5.8. These parameters were assessed from a database of 28 macroseismic intensity data points (Castelli et al. 1996), which is less than plentiful for a late 18th century earthquake. An analysis of the historical context of the 1789 earthquake and its influence on the production of contemporary accounts evidences a few research paths that previous studies either did not or could not take. Following them, the macroseismic database of the 1789 earthquake can be noticeably improved, providing the catalogue compiler with a mean to check the reliability of its current parameters

Drawing bobbin lace graphs, or, Fundamental cycles for a subclass of periodic graphs

In this paper, we study a class of graph drawings that arise from bobbin lace patterns. The drawings are periodic and require a combinatorial embedding with specific properties which we outline and demonstrate can be verified in linear time. In addition, a lace graph drawing has a topological requirement: it contains a set of non-contractible directed cycles which must be homotopic to $(1,0)$, that is, when drawn on a torus, each cycle wraps once around the minor meridian axis and zero times around the major longitude axis. We provide an algorithm for finding the two fundamental cycles of a canonical rectangular schema in a supergraph that enforces this topological constraint. The polygonal schema is then used to produce a straight-line drawing of the lace graph inside a rectangular frame. We argue that such a polygonal schema always exists for combinatorial embeddings satisfying the conditions of bobbin lace patterns, and that we can therefore create a pattern, given a graph with a fixed combinatorial embedding of genus one.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

Thermomechanical deformation behavior of a dynamic strain aging alloy, Hastelloy X

An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation tests on the solid-solution-strenghened nickel-base superalloy, Hastelloy X. This alloy exhibits a strong isothermal strain aging peak at approximately 600 C, promoted by the effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results indicate that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of macroscopic unified theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments

About the linearity of the color-magnitude relation of early-type galaxies in the Virgo cluster

We revisit the color-magnitude relation (CMR) of the Virgo cluster early-type galaxies in order to explore its alleged non-linearity. To this aim, we reanalyze the relation already published from data obtained within the ACS Virgo Cluster Survey of the Hubble Space Telescope, and perform our own photometry and analysis of the images of the 100 early-type galaxies observed as part of this survey. In addition, we compare our results with those reported in the literature from data of the Sloan Digital Sky Survey. We have found that when the brightest galaxies and untypical systems are excluded from the sample, a linear relation arises in agreement with what is observed in other groups and clusters. The central regions of the brightest galaxies also follow this relation. In addition, we notice that Virgo contains at least four compact elliptical galaxies besides the well known object VCC 1297 (NGC 4486B). Their locations in the -luminosity diagram define a different trend to that followed by normal early-type dwarf galaxies, setting an upper limit in effective surface brightness and a lower limit in effective radius for their luminosities. Based on the distribution of different galaxy sub-samples in the color-magnitude and -luminosity diagrams we draw some conclusions on their formation and the history of their evolution.Comment: 21 pages, 4 figures, 2 tables. Accepted for publication in Ap