689 research outputs found
Homogenization of the heterogeneous beam dynamics: The influence of the random Young's modulus mixing law
No full textThis paper concerns the homogenization of the dynamic response of Euler Bernoulli's beam with random Young's modulus. Considering the eigenvalue problem, special attention is dedicated to the homogenization residuals (correctors) analysis, i.e. the difference between the random heterogeneous solution and the homogenized solution. Several correlation (mixing) laws of the Young's modulus are considered and a dimensionless characteristic scale length, based on the correlation length, is introduced. The effects of the mixing law on the residuals are analyzed using numerical approaches both for sampling the random Young’ modulus and for examining the beam eigenvalue problem. Two measurements are introduced to estimate the residuals between apparent and effective solution: the normalized difference of the Young's modulus and the normalized difference of the modes' shape. The effect of the mode's order is also highlighted with reference to forced vibrations
Endogenous cycles in heterogeneous agent models: a state-space approach
No full textThis paper proposes an empirical test to identify possible endogenous cycles withinheterogeneous agent models (HAMs). We consider a two-type HAM into a standardsmall-scale dynamic asset pricing framework. Fundamentalists base their expectationson the fundamental value, while chartists consider the level of past prices. Becausethese strategies, by their nature, cannot be directly observed but can cause the responseof the observed data, we construct a state-space model where agents’ beliefs areconsidered the unobserved state components and from which the heterogeneity offundamentalist-chartist trader cycles can be mathematically derived and empiricallytested. The model is estimated using the S&P500 index for the period 1990–2020 at different time scales, specifically, quarterly, monthly, and daily. We find empiricalevidence of endogenous damped fluctuations with a higher probability of chartistbehavior in the short-term horizon. In addition, the model exhibits better long-runout-of-sample forecasting accuracy compared to the benchmark random walk model
Estimation of masonry texture and mechanical characteristics by means of thermographic images
No full textArchitectural and Environmental Impact of Retrofitting Techniques to Prevent In-Plane «Domino» Failure Modes of Unreinforced Masonry Buildings
No full textThe preservation of heritage buildings is not just about the structural safety, but it is necessarily related to the central themes of restoration, fruition and reuse of ancient buildings. Such topic requires an interdisciplinary design approach that involves, among the others, structural engineering, numerical modelling and architecture to address the challenges of contemporaneity in heritage management also in terms of interests of the stakeholders. In this regard, the opportunities offered by natural F.R.C.M. (Fibre Reinforced Cementitious Matrix) composites, made of basaltic fibres and lime mortar, are analysed. The main objective of the research is to expand the state of the art concerning the influence of such composites’ applica- tions on ≪in falso≫ masonries: load bearing walls built without a direct load path to the ground and acting like ≪wall beams≫ in case of collapse of the underlying masonry vaults. On this, an experimental campaign started in order to make a comparative assessment about the influ- ence of composites in the prevention of knock-on collapses due to the aforementioned scenario, with the benefit of avoiding damages to unmovable artistic assets and valuable architectural features (e.g. precious pavings, mosaics, vaulted surfaces etc.). Furthermore, rather than the ≪canon≫ widespread intervention, an innovative application of F.R.C.M. in tapes is proposed, aimed at interventions with reduced quantities of composite material and therefore improving its use in the heritage even more. Finally, a first approach to the 3D Finite Element formulation for the case in question is proposed
Estimation of residuals for the homogenized solution of quasi-periodic media
No full textIn this work we analyze the convergence of the elastic coefficients in terms of the residuals as the dimensions of the sample of a random two-dimensional medium vary. In particular, the case of the masonry material which can be considered a heterogeneous solid with two phases (stones or bricks and mortar) is taken into account. In particular, we consider a masonry which presents a quasi-periodic micro-structure. A procedure of numerical generation of wall portions has been developed which takes into account not only the scale ratio but also the mechanical ratio and the geometrical ratio. The convergence of residuals has been highlighted in terms of probability density function and statistical moments, up to the second order, of the stiffness coefficients and of the log-Euclidean distance between the masonry samples and the closest isotropic material
Testing fundamentalist–momentum trader financial cycles: An empirical analysis via the Kalman filter
No full textThis paper proposes an empirical test for Minskyan financial cycles in asset prices, driven by the interaction of fundamentalist and momentum traders. Both agents’ beliefs about the future are unobserved and can be modelled in a state space model. We use the Kalman filter to identify the two behavioral rules and evaluate whether the conditions for the existence of cycles hold. The model is estimated for equity and housing prices for France, Germany, the UK and the United States, for the period 1970–2017, with annual and quarterly data. We find robust empirical support for the existence of endogenous financial cycles in equity markets for all countries and for France, the UK and the United States for housing markets.</p
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