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Damped Bloch Waves in Lattices Metamaterials with Inertial Resonators
No full textThe present paper is focused on the acoustic behaviour of periodic beam-lattices metamaterials containing inertial viscoelastic resonators connected with elastic slender ligaments. A simplified model is considered where the ligaments are considered as massless and the viscoelastic resonators are contained inside rigid rings located at the lattice nodes. Firstly, a Lagrangian model is formulated in order to assess the influence of the dynamic and viscoelastic properties of the resonators on the acoustic behaviour. An equivalent generalized micropolar model is obtained through a continualization of the discrete model and the constitutive tensors and the equation of motion are formulated. The propagation of harmonic waves is assumed and the Christoffel equation for both the discrete and the continuum model are obtained. It is shown that the hermitian matrix governing the Christoffel equation of the Lagrangian model is approximated by the corresponding one from the micropolar model with an error O (|k|3
Phase field modelling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation
No full textFracture of technological thin-walled components
can notably limit the performance of their corresponding
engineering systems. With the aim of achieving reliable
fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated.
Specific details regarding the corresponding finite
element formulation and the main aspects associated with
its implementation in the general purpose packages FEAP
and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models
“Nessun dorma": International Strategies for Italian Opera House
No full textItalian Opera is a form of cultural expression that enjoyed significant international exposure in the past centuries and that still today is a major contributor of the global industry of opera performances. Yet, no comprehensive model is available to address international strategies of opera houses and cultural organisations in general. The paper addresses this gap, providing a framework to classify international activities in opera houses and then applying the model to four prominent Italian Opera Houses: Torino, Venezia, Firenze, Roma. Results highlights both the need for the industry to address the issue of the global presence of Italian opera houses from a business, artistic and cultural standpoint, and the conditions to be met for cultural organisations willing to strengthen their international presence
Different levels of visual perceptual skills are associated with specific modifications in functional connectivity and global efficiency
No full textThe disembedding ability (i.e., the ability to identify a simple masked figure within a complex one) depends on attentional mechanisms, executive functions and working memory. Recent cognitive models ascribed different levels of disembedding task performance to the efficiency of the subtended mental processes engaged during visuo-spatial perception.
Here we aimed at assessing whether different levels of the disembedding ability were associated to the functional signatures of neural efficiency, defined as a specific modulation in response magnitude and functional connectivity strength in task-related areas. Consequently, brain activity evoked by a visual task involving the disembedding ability was acquired using functional magnetic resonance imaging (fMRI) in a sample of 23 right-handed healthy individuals. Brain activity was analyzed at different levels of information processing, from local responses to connectivity interactions between brain nodes, as far as to network topological properties.
All different levels of information processing were significantly modulated by individual behavioral performance. Specifically, single voxel response magnitude, connectivity strength of the right intrahemispheric and interhemispheric edges, and graph measures (i.e., local and global efficiency) were negatively associated to behavioral performance. Altogether, these results indicate that efficiency during a disembedding task cannot be merely attributed to a reduced neural recruitment of task-specific regions, but can be better characterized as an enhanced functional hemispherical asymmetry
A magnetic compatible supernumerary robotic finger for functional magnetic resonance imaging (fMRI) acquisitions: Device description and preliminary results
No full textSummary form only given. Strong light-matter coupling has been recently successfully explored in the GHz and THz 1 range with on-chip platforms. New and intriguing quantum optical phenomena have been predicted in the ultrastrong coupling regime 2, when the coupling strength Ω becomes comparable to the unperturbed frequency of the system ω. We recently proposed a new experimental platform where we couple the inter-Landau level transition of an high-mobility 2DEG to the highly subwavelength photonic mode of an LC meta-atom 3 showing very large Ω/ωc = 0.87. Our system benefits from the collective enhancement of the light-matter coupling which comes from the scaling of the coupling Ω ∝ √n, were n is the number of optically active electrons. In our previous experiments 3 and in literature 4 this number varies from 104-103 electrons per meta-atom. We now engineer a new cavity, resonant at 290 GHz, with an extremely reduced effective mode surface Seff = 4 × 10-14 m2 (FE simulations, CST), yielding large field enhancements above 1500 and allowing to enter the few (<;100) electron regime. It consist of a complementary metasurface with two very sharp metallic tips separated by a 60 nm gap (Fig.1(a, b)) on top of a single triangular quantum well. THz-TDS transmission experiments as a function of the applied magnetic field reveal strong anticrossing of the cavity mode with linear cyclotron dispersion. Measurements for arrays of only 12 cavities are reported in Fig.1(c). On the top horizontal axis we report the number of electrons occupying the topmost Landau level as a function of the magnetic field. At the anticrossing field of B=0.73 T we measure approximately 60 electrons ultra strongly coupled (Ω/ω- |
The indirect effects of foreign direct investment on trade: A network perspective
No full textThe relationship between international trade and foreign direct investment (FDI) is one of the main features of globalisation. In this paper, we investigate the effects of FDI on trade from a network perspective, since FDI takes not only direct but also indirect channels from origin to destination countries because of firms’ incentive to reduce tax burden, to minimise coordination costs and to break barriers to market entry. We use a unique data set of international corporate control as a measure of stock FDI to construct a corporate control network (CCN), where the nodes are the countries and the edges are the corporate control relationships. Network measures, as the shortest path length and the communicability, are then computed on the CCN to capture the indirect channel of FDI. Empirically, we find that corporate control has a positive effect on trade both directly and indirectly. The result is robust with different specifications and estimation strategies. Hence, our paper provides strong empirical evidence of the indirect effects of FDI on trade. Moreover, we identify a number of interplaying factors such as regional trade agreements and the region of Asia. We also find that the indirect effects are more pronounced for the manufacturing sector than for primary sectors such as oil extraction and agriculture
Spatio-Temporal Patterns of the International Merger and Acquisition Network
Full text linkThis paper analyses the world web of mergers and acquisitions (M&As) using a complex network approach. We use data of
M&As to build a temporal sequence of binary and weighted-directed networks for the period 1995-2010 and 224 countries
(nodes) connected according to their M&As flows (links). We study different geographical and temporal aspects of the international
M&A network (IMAN), building sequences of filtered sub-networks whose links belong to specific intervals of distance
or time. Given that M&As and trade are complementary ways of reaching foreign markets, we perform our analysis using
statistics employed for the study of the international trade network (ITN), highlighting the similarities and differences between
the ITN and the IMAN. In contrast to the ITN, the IMAN is a low density network characterized by a persistent giant component
with many external nodes and low reciprocity. Clustering patterns are very heterogeneous and dynamic. High-income
economies are the main acquirers and are characterized by high connectivity, implying that most countries are targets of a few
acquirers. Like in the ITN, geographical distance strongly impacts the structure of the IMAN: link-weights and node degrees
have a non-linear relation with distance, and an assortative pattern is present at short distances
