Collisions of self-bound quantum droplets

We report on the study of binary collisions between quantum droplets formed by an attractive mixture of ultracold atoms. We distinguish two main outcomes of the collision, i.e. merging and separation, depending on the velocity of the colliding pair. The critical velocity $v_c$ that discriminates between the two cases displays a different dependence on the atom number $N$ for small and large droplets. By comparing our experimental results with numerical simulations, we show that the non-monotonic behavior of $v_c(N)$ is due to the crossover from a compressible to an incompressible regime, where the collisional dynamics is governed by different energy scales, i.e. the droplet binding energy and the surface tension. These results also provide the first evidence of the liquid-like nature of quantum droplets in the large $N$ limit, where their behavior closely resembles that of classical liquid droplets

Neutron Transverse-Momentum Distributions and Polarized 3He within Light-Front Hamiltonian Dynamics

The possibility to extract the quark transverse-momentum distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He is illustrated through an impulse approximation analysis in the Bjorken limit. The generalization of the analysis at finite momentum transfers in a Poincare' covariant framework is outlined. The definition of the light-front spin-dependent spectral function of a J=1/2 system allows us to show that within the light-front dynamics only three of the six leading twist T-even transverse-momentum distributions are independent.Comment: 4 pages, 2 figures, Presented at the 20th International IUPAP Conference on Few-Body Problems in Physics, 20 - 25 August, 2012, Fukuoka, Japa

From the Birth of the Soundscape Concept to the Sound Ambient in Disneyland-Paris

Giovanni De Zorzi traces the historical and aesthetical background of ‘soundscape’, from the sound/noise opposition in physics to the reconsideration of ‘noise’ by the avant-gardes of the twentieth century arriving to the conceptions of Murray Schafer and Steven Feld, which gave birth to many nowadays disciplines. After this, Alessio Calandra deals with the possible influence of the soundscape of Disneyland Park, an amusement park in Disneyland Paris: he begins from some ‘physical’ places of the Park, such as Main Street U.S.A., Frontierland, Adventureland, and arrives to the detailed analysis of their specific soundscape related to the sale of Disney-branded gadgets and products within the park

Energy analysis of a transcritical CO2 supermarket refrigeration system with heat recovery

Carbon dioxide (R744) is widely used as refrigerant in supermarkets located in cold weather sites thanks to its negligible environmental impact and its favourable thermo-physical properties. Due to its low critical temperature, transcritical operations in CO2 refrigeration systems can commonly take place, increasing the energy consumption substantially. On the other hand, the high temperatures reached by the CO2 in the high pressure heat exchanger (gas cooler) potentially allow recovering a large amount of heat at different temperature levels according to the supermarket needs. The paper deals with the energy performance evaluation of a R744 refrigeration system, which provides the selected supermarket with DHW and heating, besides satisfying the cooling load required by the refrigerated and frozen food storage equipment. The system is equipped with an additional air-cooled evaporator which can be used as a supplemental heat source, to increase the amount of heat recovered and meet the full heating demand of the building. Different control strategies are examined in order to minimize the electric consumption and, contemporary, maximize the heat recovery

Comparative Evaluation of Packet Classification Algorithms for Implementation on Resource Constrained Systems

This paper provides a comparative evaluation of a number of known classification algorithms that have been considered for both software and hardware implementation. Differently from other sources, the comparison has been carried out on implementations based on the same principles and design choices. Performance measurements are obtained by feeding the implemented classifiers with various traffic traces in the same test scenario. The comparison also takes into account implementation feasibility of the considered algorithms in resource constrained systems (e.g. embedded processors on special purpose network platforms). In particular, the comparison focuses on achieving a good compromise between performance, memory usage, flexibility and code portability to different target platforms

Photorealistic True-Dimensional Visualization of Remote Panoramic Views for VR Headsets

© 2023 IEEE. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/Virtual Reality headsets have evolved to include unprecedented display quality. Meantime, they have become light-weight, wireless and low-cost, which has opened to new applications and a much wider audience. Photo-based omnidirectional imaging has also developed, becoming directly exploitable for VR, with their combination proven suitable for: remote visits and realistic scene reconstruction, operator’s training and control panels, surveillance and e-tourism. There is however a limited amount of scientific work assessing VR experience and user’s performance in photo-based environment representations. This paper focuses on assessing the effect of photographic realism in VR when observing real places through a VR headset, for two different pixel-densities of the display, environment types and familiarity levels. Our comparison relies on the observation of static three-dimensional and omnidirectional photorealistic views of environments. The aim is to gain an insight about how photographic texture can affect perceived realness, sense of presence and provoked emotions, as well as perception of image-lighting and actual space dimension (true-dimension). Two user studies are conducted based on subjective rating and measurements given by users to a number of display and human factors. The display pixel-density affected the perceived image-lighting and prevailed over better lighting specs. The environment illumination and distance to objects generally played a stronger role than display. The environment affected the perceived image-lighting, spatial presence, depth impression and specific emotions. Distances to a set of objects were generally accurately estimated. Place familiarity enhanced perceived realism and presence. They confirmed some previous studies, but also introduced new elements.Peer reviewe