Regularity for general functionals with double phase

We prove sharp regularity results for a general class of functionals of the type $$w \mapsto \int F(x, w, Dw) \, dx\;,$$ featuring non-standard growth conditions and non-uniform ellipticity properties. The model case is given by the double phase integral $$w \mapsto \int b(x,w)(|Dw|^p+a(x)|Dw|^q) \, dx\;,\quad 1 <p < q\,, \quad a(x)\geq 0\;,$$ with $0<\nu \leq b(\cdot)\leq L$. This changes its ellipticity rate according to the geometry of the level set $\{a(x)=0\}$ of the modulating coefficient $a(\cdot)$. We also present new methods and proofs, that are suitable to build regularity theorems for larger classes of non-autonomous functionals. Finally, we disclose some new interpolation type effects that, as we conjecture, should draw a general phenomenon in the setting of non-uniformly elliptic problems. Such effects naturally connect with the Lavrentiev phenomenon

Additive manufacturing of silicon carbide by selective laser sintering of PA12 powders and polymer infiltration and pyrolysis

Abstract In this work, we propose a novel hybrid additive manufacturing technique, which combines selective laser sintering (SLS) of polyamide powders and subsequent preceramic polymer infiltration and pyrolysis to manufacture Silicon Carbide components for complex architectures. By controlling the porosity of the sintered polymeric preform we are able to control the shrinkage upon the first infiltration and pyrolysis. This enabled the manufacturing of smaller features than those achievable with other manufacturing techniques. The mechanical strength of the resulting ceramic increased with the number of reinfiltration cycles up to 24 MPa, inversely the residual porosity decreased to 10 vol%. The microstructure showed two distinct phases of SiOC and SiC. The first was attributed to the interaction between the porous polyamide and the ceramic precursor during the first infiltration. SiC derived from the pyrolysis of the preceramic precursor alone

3D printed geopolymeric lattices: Effect of different filler materials on mechanical properties

Our group developed mixtures based on geopolymer for additive manufacturing of porous components via direct ink writing (DIW). We optimized the rheological properties in order to obtain suitable inks for the production of highly porous lattices. It should be noted that, as geopolymer mixtures are subjected to ongoing poly-condensation reactions, their viscosity changes with time in what can be seen as a 4D printing process. Different materials were added to the mixture, such as glass and plastic fibers, as well as fillers like sand, to produce innovative 3D printed geopolymeric composites. The influence of these materials on the mechanical properties was evaluated

Design for Emergency: An Open Platform to Design and Implement User-Centered Solutions in the COVID-19 Pandemic

As a consequence of the lockdown enforced to fight the COVID-19 pandemic, people found themselves in a state of social isolation, uncertainty, and vulnerability. Design for Emergency is a data and design open platform launched to ideate and develop user-centered solutions addressing people’s needs and emotions during and after the lockdown. The project is made of four stages: data collection, data analysis &amp; visualization, design, and implementation. The initiative started in Italy, but it soon became global, extending to 11 countries in three continents. As a result, we collected and visualized data about people’s experiences during the pandemic at a global level. Our ideas platform, still growing, includes 36 seed ideas of solutions helping individuals and communities cope with the pandemic. Ideas are openly available for development by anyone, and some of them are currently being implemented. This initiative can be used as a reference and a pilot project to create a framework for designing in situations of uncertainty, emergency, or crisis, where design can quickly discover and address emerging feelings and needs

Large scale additive manufacturing of artificial stone components using binder jetting and their X-ray microtomography investigations

Abstract Additive manufacturing of large scale parts is an innovative, challenging research field, with the potential of producing parts with complex structures, specific functional and structural properties. In this study, binder jetting was employed using two different large scale printers to fabricate non-structural parts made of artificial stone. The printing bed was comprised of aggregates (River sand and Poraver expanded glass) and reactive magnesium oxide and potassium phosphate powders, which were activated by selectively depositing water, layer after layer. The exothermic reaction between reactive powders and water generates in situ a hydraulic inorganic binder, that binds the aggregates in the bed. The reaction parameters were controlled to achieve a fast setting, enabling rapid printing at the macro-scale (in the range of tens of centimeters or meters). The influence of the voxel size of the printers on the microstructure and printing quality of the fabricated parts, their physical and mechanical properties as well as the in situ formation of the cement phase were investigated by X-ray microtomography

Visual Geolocations. Repurposing online data to design alternative views

Data produced by humans and machines is more and more heterogeneous, visual, and location based. This availability inspired in the last years a number of reactions from researchers, designers, and artists that, using different visual manipulations techniques, have attempted at repurposing this material to add meaning and design new perspectives with specific intentions. Three different approaches are described here: the design of interfaces for exploring satellite footage in novel ways, the analysis of urban esthetics through the visual manipulation of collections of user-generated contents, and the enrichment of geo-based datasets with the selection and rearrangement of web imagery

Porous Geopolymer Components

Geopolymers are based on an inorganic 3D network of alumino-silicate units usually synthesized through reaction of alumino-silicate powders in presence of a silicate alkaline solution. The rheological characteristics of the reactive mixtures and the fact that these systems can consolidate at low or even room temperature, together with their intrinsic micro- and meso-porosity and mechanical properties, are the reason why they are considered for a wide range of applications, such as construction materials, thermal insulation, filters, adsorbers and so on. Open cell alkali or acid-based geopolymer foams were produced by direct foaming using different fabrication approaches. Potassium-based foams with a porosity up to 85 vol% were obtained from metakaolin, potassium silicate and potassium hydroxide, while metakaolin and phosphoric acid were used to fabricate foams containing an aluminum phosphate crystal phase already after synthesis at room temperature, and a total porosity of ~80 vol%. The strength of the foams depended on the porosity of the components as well as the heat treatment temperature. Components with designed, non-stochastic porosity were also produced by additive manufacturing, specifically Direct Ink Writing. Paste with suitable pseudo-plastic rheology were developed and we fabricated components with overhangs and spanning features, including highly porous 3D lattices

Cordierite ceramics from silicone resins containing nano-sized oxide particle fillers

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