Search results for "Statistical physics"
showing 10 items of 1402 documents
Probabilistic quantum clustering
2020
Abstract Quantum Clustering is a powerful method to detect clusters with complex shapes. However, it is very sensitive to a length parameter that controls the shape of the Gaussian kernel associated with a wave function, which is employed in the Schrodinger equation with the role of a density estimator. In addition, linking data points into clusters requires local estimates of covariance which requires further parameters. This paper proposes a Bayesian framework that provides an objective measure of goodness-of-fit to the data, to optimise the adjustable parameters. This also quantifies the probabilities of cluster membership, thus partitioning the data into a specific number of clusters, w…
Diffusion of theories and theoretical models in the Ibero‐American research on information behavior
2021
Ibero-American research on information behavior (IB) lacks the visibility typical of other parts of the world, and little is known about it in countries outside the area. The objective of this paper has therefore been to analyze the way in which Ibero-American research incorporates various theoretical references to empirical research on IB. The results point to the existence of different focuses of research in the past 10 years, in the sense of a reduced empirical approach and a moderate to minimal use of theories in the design of such research. Furthermore, the most cited theories and models of IB at an international level are those most widely applied in this geographical area, and the us…
Update of the Binoth Les Houches Accord for a standard interface between Monte Carlo tools and one-loop programs
2014
We present an update of the Binoth Les Houches Accord (BLHA) to standardise the interface between Monte Carlo programs and codes providing one-loop matrix elements.
Thermodynamics-based gradient plasticity theories with an application to interface models
2008
AbstractIn the framework of small deformations, the so-called residual-based gradient plasticity theory is reconsidered and improved. Using the notion of moving geometrically necessary dislocations (GNDs), suitable micromechanics interpretations are heuristically given for the higher order boundary conditions and the long distance particle interactions. Also, a comparison is made between this theory and the analogous virtual work principle (VWP)-based one, whereby their respective conceptual and methodological features are pointed out. The conditions under which the two theories lead to a same constitutive model are investigated, showing that, correspondingly, a certain indeterminacy exhibi…
A Thermodynamic Plasticity Formulation with Local and Nonlocal Internal Variables
2002
In order to obtain the elastic response of nonhomogeneous materials, it is often sufficient to adopt an implicit homogenization technique which allows one to treat the material as an equivalent continuum medium. For large stress concentration or for accurate small scale studies this widely applied technique may show some limit and a more refined analysis might be required involving nonlocal elastic effects, see e.g. Kroner (1967), Eringen et al. (1977).
Model Exploration and Computer Experiments
2017
This chapter contains a description of a set of simulation experiments for exploration of the agent-based model proposed in the present work, devised to illustrate the model’s generative capacity and highlight the influence of the newly introduced mechanisms on the complexity of the solutions. The first experiment shows the influence of the critical “cop”-to-“active” ratio ρ c in the risk perception model on the size, duration, and recurrence of rebellion peaks. The relationship between ρ c , the occurrence of cascades and the maximum possible peak size was demonstrated analytically and then studied via computer simulations. It was shown that the value of ρ c has a strong impact on the stab…
The resemblance of an autocorrelation function to a power spectrum density for a spike train of an auditory model
2013
In this work we develop an analytical approach for calculation of the all-order interspike interval density (AOISID), show its connection with the autocorrelation function, and try to explain the discovered resemblance of AOISID to the power spectrum of the same spike train.
Level-Crossing Rate and Average Duration of Fades in Non-Isotropic Hoyt Fading Channels with Applications to Selection Combining Diversity
2015
In this paper, we investigate the second-order statistics of Hoyt fading channels under non isotropic scattering scenarios. Assuming an asymmetrical Doppler power spectral density (PSD), we derive, in the form of single finite-range integrals, expressions for the level-crossing rate (LCR) and average duration of fades (ADF). These new results are then applied to obtain the LCR and ADF of selection combining (SC) diversity over non-isotropic Hoyt channels. In addition to their importance for studying the system performance and characterizing the dynamic behavior of multipath fading channels, the formulas derived are general in that they can be applied to many non-isotropic scattering situati…
Transient Dynamics of Short Josephson Junctions under the influence of non-Gaussian Noise
2009
We investigate the effects of non-Gaussian white noise source on the transient dynamics of short Josephson junctions. The noise signal is simulated generating standard stable random variables with characteristic function described by Lévy index alpha and asymmetry parameter beta. We study the lifetime of the superconductive state as a function both of the frequency of the external driving bias current and the noise intensity for different values of index alpha. We compare our results with those obtained in the presence of Gaussian white noise. We find the presence of noise induced effects such as resonant activation and noise enhanced stability.
Josephson-based Threshold Detector for Lévy-Distributed Current Fluctuations
2019
We propose a threshold detector for Lévy-distributed fluctuations based on a Josephson junction. The Lévy-noise current added to a linearly ramped bias current results in clear changes in the distribution of switching currents out of the zero-voltage state of the junction. We observe that the analysis of the cumulative distribution function of the switching currents supplies information on both the characteristics' shape parameter α of the Lévy statistics. Moreover, we discuss a theoretical model, which allows characteristic features of the Lévy fluctuations to be extracted from a measured distribution of switching currents. In view of these results, this system can effectively find an appl…