Crossings as a side effect of dependency lengths

The syntactic structure of sentences exhibits a striking regularity: dependencies tend to not cross when drawn above the sentence. We investigate two competing explanations. The traditional hypothesis is that this trend arises from an independent principle of syntax that reduces crossings practically to zero. An alternative to this view is the hypothesis that crossings are a side effect of dependency lengths, i.e. sentences with shorter dependency lengths should tend to have fewer crossings. We are able to reject the traditional view in the majority of languages considered. The alternative hypothesis can lead to a more parsimonious theory of language.Comment: the discussion section has been expanded significantly; in press in Complexity (Wiley

Chronicles of a disagreement foretold. CEPS Commentary, 28 November 2012

In the wake of the collapsed talks on a new EU budget for 2014-20, a new CEPS Commentary by Jorge Núñez Ferrer allows that there is a good chance that agreement will be reached before the summer but that the instrument will remain largely disconnected from the fundamental needs of the EU, foremost of which is the imperative to address imbalances in the eurozone

Decoding least effort and scaling in signal frequency distributions

Here, assuming a general communication model where objects map to signals, a power function for the distribution of signal frequencies is derived. The model relies on the satisfaction of the receiver (hearer) communicative needs when the entropy of the number of objects per signal is maximized. Evidence of power distributions in a linguistic context (some of them with exponents clearly different from the typical ß ˜ 2 of Zipf's law) is reviewed and expanded. We support the view that Zipf's law reflects some sort of optimization but following a novel realistic approach where signals (e.g. words) are used according to the objects (e.g. meanings) they are linked to. Our results strongly suggest that many systems in nature use non-trivial strategies for easing the interpretation of a signal. Interestingly, constraining just the number of interpretations of signals does not lead to scaling.Peer ReviewedPostprint (author's final draft

Study of the model-order reduction of the aerolastic behavior of a wing

The  ultimate goal of this project is to construct a   reduced-order model capable of  providing real-time predictions of   the aeroelastic behavior of a wing.  The approach for carrying out such a task is, firstly, in the spirit of classic modal analysis, to project the full-order, governing equations of the wing (finite element equations, for instance) onto the low-dimensional subspace spanned by a few global displacement modes. Such displacement modes, in turn, are obtained by applying data compression algorithms  to a representative set of full-order simulations.   Once these dominant displacement modes have been identified, the next step in the approach is to choose, among all points of the underlying finite element mesh,  a set of sampling points  so that the integrals appearing in the weak form of the balance equation can be accurately evaluated by monitoring the strains and stresses only at such key points.The main objective of this paper is to apply the model-order reduction technique to an airplane’s wing in order to speed up development of aircrafts or to get real-time results of a plane structural state. However, this case is especially complex since the wings are an aeroelastic problem where both fluid and structure must be computed in order to get realistic results. In order to improve the overall airplane design speed -in addition to the usage of MOR techniques- a complementary software has been developed. This is a parametric software capable of quickly generating a geometry and exporting it to simulate both the fluid and the structure with a FE software like Kratos. This software will be open sourced. The usage of the custom software helps to generate geometries that differ only on a single design parameter (the angle of attack in this paper). These different geometries are then processed with Kratos to obtain the high-fidelity result from each one of them. Once the high-fidelity snapshots have been obtained (five are used in this paper), the reduced order models are generated using a discrete version of the Proper Orthogonal Decomposition (POD) called Single Value Decomposition (SVD). Finally, using the discrete empirical interpolation method (DEIM), it is possible to interpolate between the simulations and obtain the results of any intermediate state in less than a second without having to perform the full simulation. No physical model has been constructed to compute the fluid and only statistical methods are employed for that part. The results turned out to be very precise regarding the structure ROM; all the same, the only statistical approach to the fluid proved to be not ideal and the accuracy error remained around 15% for this part