Mesh sensitivity in discrete element simulation of flexible protection structures

The Discrete Element Method (DEM) has been employed in recent years to simulate flexible protection structures undergoing dynamic loading due to its inherent aptitude for dealing with inertial effects and large deformations. The individual structural elements are discretized with an arbitrary number of discrete elements, connected by spring-like remote interactions. In this work, we implement this approach using the parallel bond contact model and compare the numerical results at different discretization intervals with the analytical solutions of classical beam theory. Successively, we use the same model to simulate the punching test of a steel wire mesh and quantify the influence of a different number of elements on the macroscopic response

Quando l'idea acquista spessore: tecnologie additive a confronto

"Le “nuove” tecnologie additive [1] stanno cambiando il mondo del manufacturing sia in termini di progettazione sia di modalità di produzione; tale rinnovamento si traduce, di fatto, nella realizzazione secondo una nuova modalità di oggetti dalle caratteristiche più svariate. Il miglioramento più evidente si è avuto grazie al superamento dei tradizionali vincoli che, per esempio, la produzione con stampi comporta; il principale vantaggio ottenuto è l’enorme fl essibilità che le nuove tecnologie additive garantiscono, fl essibilità da intendersi sia in termini di forme e materiali, sia in relazione alla grande varietà di pezzi differenti che è possibile realizzare contemporaneamente

Geopan at@s: A brokering based gateway to georeferenced historical maps for risk analysis

Importance of ancient and historical maps is nowadays recognized in many applications (e.g., urban planning, landscape valorisation and preservation, land changes identification, etc.). In the last years a great effort has been done by different institutions, such as Geographical Institutes, Public Administrations, and collaborative communities, for digitizing and publishing online collections of historical maps. In spite of this variety and availability of data, information overload makes difficult their discovery and management: Without knowing the specific repository where the data are stored, it is difficult to find the information required. In addition, problems of interconnection between different data sources and their restricted interoperability may arise. This paper describe a new brokering based gateway developed to assure interoperability between data, in particular georeferenced historical maps and geographic data, gathered from different data providers, with various features and referring to different historical periods. The developed approach is exemplified by a new application named GeoPAN Atl@s that is aimed at linking in Northern Italy area land changes with risk analysis (local seismicity amplification and flooding risk) by using multi-Temporal data sources and historic maps

Remote cutting of Li-ion battery electrodes with infrared and green ns-pulsed fibre lasers

"Thin sheet anode and cathode materials made in composite structures constitute some of the most important components of a Li-ion battery. These materials are currently cut by punching technology, which shows degrading behaviour as the tool wears out. A viable option for Li-ion battery electrode manufacturing is the use of remote laser cutting. However, the operation requires fulfilling both productivity and quality aspects to substitute the conventional production method. One of the most critical aspects in quality is the clearance width, which is defined as the extent of the exposed middle layer of the sandwich at the laser cut kerf. This work investigates the quality aspects of laser cutting of Li-ion electrodes when a green fibre laser source (λ=532 nm, τ= 1 ns) is used rather than the more traditional infrared (IR) fibre laser source (λ=1,064 nm, τ=250 ns). The processing conditions were investigated to reveal the technological feasibility zones. Clearance width was studied within the technological feasibility zones for all the material-laser combinations. Results showed that high productivity criterion is met by the IR system, since cutting speed could reach 30 m/min with 54Waverage laser power on both anode and cathode. On the other hand, the green laser provided clearance width below 20 μm. In the best case, the clearance on anode could be eliminated with the green laser system. Although the maximum cutting speed was 4.5 m/min, upscaling of green laser power can provide required productivity.

Micro-Drilling of ZTA and ATZ Ceramic Composit: Effect of Cutting Parameters on Surface Roughness

Ceramics are a class of materials widely used during last fifteen years for orthopaedic applications. It is well known that they are characterized by low wear rate, and friction coefficient. However, these materials are very difficult to machine into complex shapes because of their brittleness and high hardness. The most effective method to increase the crack resistance is the formation of a composite structure. This class of materials, composed by two or more different ceramics, can present higher characteristic respect to the single component, like fracture toughness and flexural strength. This paper presents a study of the influence of cutting parameters (cutting speed, feed rate and step number) onto the hole surface roughness and deformation due to the drill operation. The ceramic composite materials AZT (alumina toughened zirconia) and ZTA (zirconia toughened alumina) were first characterized in terms of hardness and roughness. After the drilling test, the holes were analyzed using scanning electron microscope (SEM) and an advanced 3-dimensional non-contact optical profilomete

A flexible scintillation light apparatus for rare event searches

Compelling experimental evidences of neutrino oscillations and their implication that neutrinos are massive particles have given neutrinoless double beta decay a central role in astroparticle physics. In fact, the discovery of this elusive decay would be a major breakthrough, unveiling that neutrino and antineutrino are the same particle and that the lepton number is not conserved. It would also impact our efforts to establish the absolute neutrino mass scale and, ultimately, understand elementary particle interaction unification. All current experimental programs to search for neutrinoless double beta decay are facing with the technical and financial challenge of increasing the experimental mass while maintaining incredibly low levels of spurious background. The new concept described in this paper could be the answer which combines all the features of an ideal experiment: energy resolution, low cost mass scalability, isotope choice flexibility and many powerful handles to make the background negligible. The proposed technology is based on the use of arrays of silicon detectors cooled to 120 K to optimize the collection of the scintillation light emitted by ultra-pure crystals. It is shown that with a 54 kg array of natural CaMoO4 scintillation detectors of this type it is possible to yield a competitive sensitivity on the half-life of the neutrinoless double beta decay of 100Mo as high as ~10E24 years in only one year of data taking. The same array made of 40CaMoO4 scintillation detectors (to get rid of the continuous background coming from the two neutrino double beta decay of 48Ca) will instead be capable of achieving the remarkable sensitivity of ~10E25 years on the half-life of 100Mo neutrinoless double beta decay in only one year of measurement.Comment: 12 pages, 4 figures. Prepared for submission to EPJ

Codice etico, modelli organizzativi e responsabilità amministrativa: l’applicazione del D.Lgs 231/2001 alle società di calcio professionistiche

Introduzione – 1. La responsabilità amministrativa – 2. Il modello organizzativo ex D. Lgs 231/2001 – 3. Le attività a rischio di reato – 4. Responsabilità sociale e modello organizzativo – Conclusioni – Bibliografia