No abstract

Social media allow to fulfill perceived social needs such as connecting with friends or other individuals with similar interests into virtual communities; they have also become essential as news sources, microblogging platforms, in particular, in a variety of contexts including that of health. However, due to the homophily property and selective exposure to information, social media have the tendency to create distinct groups of individuals whose ideas are highly polarized around certain topics. In these groups, a.k.a. echo chambers, people only "hear their own voice,” and divergent visions are no longer taken into account. This article focuses on the study of the echo chamber phenomenon in the context of the COVID-19 pandemic, by considering both the relationships connecting individuals and semantic aspects related to the content they share over Twitter. To this aim, we propose an approach based on the application of a community detection strategy to distinct topology- and content-aware representations of the COVID-19 conversation graph. Then, we assess and analyze the controversy and homogeneity among the different polarized groups obtained. The evaluations of the approach are carried out on a dataset of tweets related to COVID-19 collected between January and March 2020.

Over the years the production of steel through electric arc furnace (EAF) technology has increased more and more, allowing the EAF to compete more successfully with the integrated mills; to the will to reduce the amount of CO 2 and dust emission have further encouraged the steel production through this technology. In 2019, the EAF crude steel production reached 517 million tons, corresponding to the 27.7% of the worldwide production. [1] In Italy, the scrap-based route covers a crucial role with 37 EAF production sites and a crude steel production share of 82%. [2,3] The electric furnace process has evolved becoming a highly efficient scrap smelter, which integrate a technology able to improve energy using oxygen, gas, carbon, and lime injection. Generally, the lime charging procedure into the EAF is based on lime addition, in the form of lumps, directly within the scrap bucket through conveyor systems. This practice, however, has several issues related with lime emissions during the scrap bucket charging and an inadequate distribution of lime in the furnace, made possible instead by lime injection. [4] In recent years, the usage of pneumatic injection of lime in EAFs, due to its surprising results in terms of reduction of the specific raw material consumption, foaming benefits, operational cost benefits, and improvement in environmental aspects, has acquired interest as a viable technology for the steelmaking industry. [5] Acciaierie di Calvisano steelmaking plant, in collaboration with Unicalce S.p.A., decided to upgrade its EAF, implementing a new system of lime delivering, in place of the traditional procedure. Combining carbon and lime powder injectors, the lances are able to create a homogeneous layer of foamy slag over the whole metal bath surface. The addition of lime is essential for the proper bath chemistry and the slag foaming practice, which offers an increased energy efficiency of the furnace, since the heat from the arc is captured by the slag; a protection of the water panels and the roof from radiation and a decreased noise pollution and low nitrogen incorporation in the steel are

Inspired by the abilities of contemporary autonomous vehicles to navigate with a high degree of effectiveness, the INSPEX Project 1 seeks to minaturise the sensing and processing technology involved, to produce devices which can help navigate within an environment in a smart way, enabling their use in a wide variety of applications. The project is focused on producing an advanced prototype for a device which can be attached to a VIB person's white cane, and which, through the use of a variety of minaturised sensors, and of the processing of their data via sophisticated algorithms, can offer the user a richer palette of information about the environment than the use of the unadorned white cane alone could furnish. The various strands contributing to the project are overviewed, and the prospects for further enhancements are contemplated.

The underground oil-filled cable consists of a hollow copper conductor surrounded by oiled paper which acts as electrical insulation. The oil flows along the conductor and diffuses through it to the insulating paper. A lead sheath is used as the outer retaining wall. As the deterioration of this cover may cause a loss of insulation fluid, its detection is very important since this high voltage and power cable is used in cities even under sidewalks. The method of perfluorocarbon vapor tracers, based on the injection and subsequent detection of these volatile chemical substances in the vicinity of the cable, is one of the most promising methods, so far used in combination with gas chromatography and mass spectrometry. In this study, the possibility of detecting two different tracers, C 6 F 12 and C 7 F 14 , by means of resonant photoacoustic spectroscopy is studied. The beam from a tunable amplitude-modulated CO 2 laser goes through an aluminum cell with quarter wave filters at both ends of an open resonator and an electret microphone in its center, attached to the walls. The calibration of the system for either substance diluted in chromatographic air showed a higher sensitivity for C 7 F 14 , so the experiment was completed checking the behavior of this substance in samples prepared with ambient air in order to analyze the application of the system to field studies.