Modelling elastic structures with strong nonlinearities with application to stick-slip friction

An exact transformation method is introduced that reduces the governing equations of a continuum structure coupled to strong nonlinearities to a low dimensional equation with memory. The method is general and well suited to problems with point discontinuities such as friction and impact at point contact. It is assumed that the structure is composed of two parts: a continuum but linear structure and finitely many discrete but strong nonlinearites acting at various contact points of the elastic structure. The localised nonlinearities include discontinuities, e.g., the Coulomb friction law. Despite the discontinuities in the model, we demonstrate that contact forces are Lipschitz continuous in time at the onset of sticking for certain classes of structures. The general formalism is illustrated for a continuum elastic body coupled to a Coulomb-like friction model

Asset prices and financial imbalances in CEE countries: macroeconomic risks and monetary strategy

Modern central banks have adopted a ‘risk management’ approach in assessing and presenting risks to macroeconomic stability. This paper seeks to contribute to the improvement of central banks’ current strategies for Central and Eastern European countries, first by assessing the potential size of macroeconomic risks, and secondly by empirically relating these risks to certain selected financial variables. Our results suggest that risks to GDP and the Price Level are significantly higher than commonly supposed based on a normal distribution of their cyclical components. However, relating these risks to the selected financial variables generated mixed results and is rarely significant in economic terms. We conclude that central banks currently risk underestimating the probability of large deviations in GDP and Price Level from their trends. A combination of financial variables and the inclusion of international financial variables could result in more significant results than the ones used separately in this study, when looking for useful indicators of such events.central bank policy, financial imbalances, GDP-at-risk, CPI-at-risk

Twelve type II-P supernovae seen with the eyes of Spitzer

Core-collapse supernovae (CC SNe), especially those of type II-plateau (II-P), are thought to be important contributors to cosmic dust production. The most obvious indicator of the presence of newly-formed and/or pre-existing dust is the time-dependent mid-infrared (MIR) excess coming from the environment of SNe. Our goal was to collect publicly available, previously unpublished measurements on type II-P (or peculiar IIP) SNe from the Spitzer database. The temporal changes of the observed fluxes may be indicative of the underlying supernova, while spectral energy distribution (SED) fitting to the fluxes in different IRAC channels may reveal the physical parameters of the mid-IR radiation, presumably due to warm dust. IRS spectra were extracted and calibrated with SPICE, while photometric SEDs were assembled using IRAF and MOPEX. Calculated SEDs from observed fluxes were fit with simple dust models to get basic information on the dust presumed as the source of MIR radiation. We found twelve SNe satisfying the criterion above, observed at late-time epochs (typically after +300 days). In three cases we could not identify any point source at the SN position on late time IRAC images. We found two SNe, 2005ad and 2005af, which likely have newly-formed dust in their environment, while in the other seven cases the observed MIR flux may originate from pre-existing circumstellar or interstellar dust. Our results support the previous observational conclusions that warm new dust in the environment of SNe contributes only marginally to cosmic dust content.Comment: Accepted for publication in Astronomy and Astrophysics; 15 pages, 8 figures, 9 tables (Ver. 2.: language edited version, minor corrections were made in the title, in the text, and in the reference list

PARAMETER SENSITIVITY MAPS OF SURFACE GEOELECTRIC ARRAYS II. NONLINEAR AND FOCUSSED ARRAYS

In this paper we present, at first time in a geophysical journal, parameter sensitivity maps of nonlinear and focussed electrode arrays. We present them as anomalies due to electric dipoles forming on opposing surfaces of an elementary cube within the subsurface at three different depths, and not only the total effect of the dipole, but also of its components are shown. Parameter sensitivity maps of non-linear arrays, compared to those of linear arrays, have in general 1. more equal sensitivity values in x and y directions, 2. more chances for antisymmetry axes, 3. smoother lateral distribution of sensitivity values. We recommend a systematic use of parameter sensitivity maps in geoelectric prospecting, both in planning and interpretation of field measurements

Decomposing the dynamics of heterogeneous delayed networks with applications to connected vehicle systems

Delay-coupled networks are investigated with nonidentical delay times and the effects of such heterogeneity on the emergent dynamics of complex systems are characterized. A simple decomposition method is presented that decouples the dynamics of the network into node-size modal equations in the vicinity of equilibria. The resulting independent components contain distributed delays that map the spatiotemporal complexity of the system to the time domain. We demonstrate that this new approach can be used to reveal new physical phenomena in heterogenous vehicular traffic when vehicles are linked via vehicle-to-vehicle (V2V) communication.Comment: The paper has been updated in response to referee comments. 5 pages, 2 figure

Magnetization of multicomponent ferrofluids

The solution of the mean spherical approximation (MSA) integral equation for isotropic multicomponent dipolar hard sphere fluids without external fields is used to construct a density functional theory (DFT), which includes external fields, in order to obtain an analytical expression for the external field dependence of the magnetization of ferrofluidic mixtures. This DFT is based on a second-order Taylor series expansion of the free energy density functional of the anisotropic system around the corresponding isotropic MSA reference system. The ensuing results for the magnetic properties are in quantitative agreement with our canonical ensemble Monte Carlo simulation data presented here.Comment: 12 pages including 4 figure