The Seiberg-Witten map for non-commutative pure gravity and vacuum Maxwell theory

In this paper the Seiberg-Witten map is first analyzed for non-commutative Yang-Mills theories with the related methods, developed in the literature, for its explicit construction, that hold for any gauge group. These are exploited to write down the second-order Seiberg-Witten map for pure gravity with a constant non-commutativity tensor. In the analysis of pure gravity when the classical space-time solves the vacuum Einstein equations, we find for three distinct vacuum solutions that the corresponding non-commutative field equations do not have solution to first order in non-commutativity, when the Seiberg-Witten map is eventually inserted. In the attempt of understanding whether or not this is a peculiar property of gravity, in the second part of the paper, the Seiberg-Witten map is considered in the simpler case of Maxwell theory in vacuum in the absence of charges and currents. Once more, no obvious solution of the non-commutative field equations is found, unless the electromagnetic potential depends in a very special way on the wave vector.Comment: Misprints corrected. References adde

Design of a Low-Cost Easy-to-Fly STOL Ultralight Aircraft in Composite Material

The paper deals with the design of an aircraft, starting from a market survey, the conceptual design loop and the preliminary choice of dimensions, and leading to the detailed design of efficient high-lift systems and a low-drag fuselage shape. Technological challenges regarding the design of low-cost systems for flap/slat retraction and a simple wing folding system are highlighted. Aiming at an efficient optimization algorithm, we developed a new integration technique between CAD, aerodynamic and structural numerical calculation. Examples deriving from this new approach are presented.

Design of a STOL Ultralight aircraft in composite material

The class of ULM (Ultra Light Machines) and light aircraft in general has attracted growing interest through Europe in recent years. Only in Italy, in the last 5-6 years, at least 10 companies have started production of ULM aircraft. There is a very active market for this class, used to promote flight at all levels and for sports aircraft. The maximum flight speed for ULM aircraft has been increased in recent years through the use of more powerful engines (100 hp instead of 64 or 80) and better aerodynamics. It is not surprising that a maximum level speed of about 280 km/h has been reached. Since the weight constraints are very strict (maximum take-off weight must be 450 kg), it is important to investigate different solutions to improve structural design, safety, flight qualities, aeroelastic behaviour and systems reliability, without raising costs. Following the experience acquired in our department in designing light and ultra light aircraft, the design of a new composite ULM is being carried out at DPA. The paper deals with the design of a STOL (Short Take-Off and Landing) ultra light aircraft, starting from a market survey, the conceptual design loop and the preliminary choice of dimensions, and leading to the detailed design of efficient high-lift systems and a low-drag fuselage shape. Technological challenges regarding the design of low-cost systems for flap/slat retraction and a simple wing folding system are highlighted

Il danno indiretto

Il capitolo, inserito nella sezione dedicata alle fattispecie di responsabilità amministrativo-contabile, descrive analiticamente gli elementi costitutivi del danno erariale indiretto e le questioni problematiche sollevate dall'istituto. In particolare si ricostruiscono i rapporti tra giudizio risarcitorio in sede ordinaria e azione di rivalsa contabile, compresa la possibilità di utilizzare le prove raccolte nel primo giudizio all'interno del secondo, la possibile concorrenza della rivalsa civilistica e dell'azione di responsabilità amministrativa e la querelle giurisprudenziale sul dies a quo di decorrenza del termine di prescrizione dell'azione innanzi alla Corte dei conti, offrendo soluzioni precarie ma possibilmente innovative ai profili critici ancora insoluti

Address-Event Signal Processing: Silicon Retina, Cochlea and Olfaction A Review

© 2021 Tayarani-Najaran and Schmuker. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). https://creativecommons.org/licenses/by/4.0/The nervous systems converts the physical quantities sensed by its primary receptors into trains of events that are then processed in the brain. The unmatched efficiency in information processing has long inspired engineers to seek brain-like approaches to sensing and signal processing. The key principle pursued in neuromorphic sensing is to shed the traditional approach of periodic sampling in favor of an the event-driven scheme that mimicks sampling as it occurs in the nervous system, where events are preferably emitted upon the change of the sensed stimulus. In this paper we highlight the advantages and challenges of event-based sensing and signal processing in the visual, auditory and olfactory domains. We also provide a survey of the literature covering neuromorphic sensing and signal processing in all three modalities. Our aim is to facilitate research in event-based sensing and signal processing by providing a comprehensive overview of the research performed previously as well as highlighting conceptual advantages, current progress and future challenges in the field.Peer reviewe