Path-integral over non-linearly realized groups and Hierarchy solutions

The technical problem of deriving the full Green functions of the elementary pion fields of the nonlinear sigma model in terms of ancestor amplitudes involving only the flat connection and the nonlinear sigma model constraint is a very complex task. In this paper we solve this problem by integrating, order by order in the perturbative loop expansion, the local functional equation derived from the invariance of the SU(2) Haar measure under local left multiplication. This yields the perturbative definition of the path-integral over the non-linearly realized SU(2) group.Comment: 26 page

MPC-based humanoid pursuit-evasion in the presence of obstacles

We consider a pursuit-evasion problem between humanoids in the presence of obstacles. In our scenario, the pursuer enters the safety area of the evader headed for collision, while the latter executes a fast evasive motion. Control schemes are designed for both the pursuer and the evader. They are structurally identical, although the objectives are different: the pursuer tries to align its direction of motion with the line- of-sight to the evader, whereas the evader tries to move in a direction orthogonal to the line-of-sight to the pursuer. At the core of the control architecture is a Model Predictive Control scheme for generating a stable gait. This allows for the inclusion of workspace obstacles, which we take into account at two levels: during the determination of the footsteps orientation and as an explicit MPC constraint. We illustrate the results with simulations on NAO humanoids

Pyroelectric effect in PZT thick films for thermal energy harvesting in low-power sensors

Abstract Thermal-electrical energy converters based on pyroelectric effect are investigated for energy harvesting and possible use in ultralow-power sensor modules. Different elements based on thick films of lead zirconate titanate (PZT) sandwiched between metal electrodes deposited on alumina substrate were fabricated and characterized. The charge extracted was stored into a capacitor comparing performances offered by different rectifying circuits. Results show that the harvested energy can be compatible with use in autonomous sensors working in low-duty-cycle switched-supply mode

Understanding the impact of demand shocks on the container port industry

The Covid-19 pandemic has severely impacted the world economy, generating an unprecedented shock that pushed carriers to adapt to the collapse of demand. Most of the related adaptation actions (e.g., blank sailings) appear as temporary initiatives being insufficient to reach a long run equilibrium. Moreover, while carriers managed to adjust their own supplied capacity to the ongoing crisis, the port sector has been greatly impacted by the fall in transport demand, not being able to counteract the demand shortages as effectively as the carriers. Against this backdrop, the paper introduces a model for assessing the effects of demand shocks (e.g., due to the pandemic) on the integration strategies of carriers. We focus on the possible initiatives that demand shocks may trigger on the horizontal and vertical integration among the actors of the shipping industry. In doing so, the present study provides useful insights for better understanding potential future market modifications and their impact on social welfare. Using non-cooperative games, profit-maximising strategies, in case of such integrations, are compared in order to study how carriers and terminal operators might react to demand shocks in the medium and long run

L’objection de conscience au mariage homosexuel entre sécularisation et règles religieuses

L’objection de conscience au mariage homosexuel exprime une forme de réaffirmation du primat des règles religieuses sur la sexualité par rapport aux normes séculières. En ce sens, nous introduirons une brève réflexion sur le rôle que, dans l’histoire des systèmes politiques, le mariage canonique a eu dans la définition des rôles sexuels, prescrivant, en fonction du mariage, les règles pour leur union. A l'issue de cette reconstruction, nous essaierons de clarifier la manière dont l'objection de conscience au mariage homosexuel représente un moyen de réaffirmer la primauté du droit religieux sur le droit séculier dans le domaine de la sexualité