An innovative, fast and facile soft-template approach for the fabrication of porous PDMS for oil-water separation

Oil wastewater and spilled oil caused serious environmental pollution and damage to public health in the last years. Therefore, considerable efforts are made to develop sorbent materials able to separate oil from water with high selectivity and sorption capacity. However most of them are low reusable, with low volume absorption capacity and poor mechanical properties. Moreover, the synthesis is time-consuming, complex and expensive limiting its practical application in case of emergency. Here we propose an innovative approach for the fabrication of porous PDMS starting from an inverse water-in-silicone procedure able to selectively collect oil from water in few seconds. The synthesis is dramatically faster than previous approaches, permitting the fabrication of the material in few minutes independently from the dimension of the sponges. The porous material evidenced a higher volume sorption capacity with respect to other materials already proposed for oil sorption from water and excellent mechanical and reusability properties.This innovative fast and simple approach can be successful in case of emergency, as oil spill accidents, permitting in situ fabrication of porous absorbents

Isogeometric analysis of plane-curved beams

A curved beam element based on the Timoshenko model and non-uniform rational B-splines (NURBS) interpolation both for geometry and displacements is presented. Such an element can be used to suitably analyse plane-curved beams and arches. Some numerical results will explore the effectiveness and accuracy of this novel method by comparing its performance with those of some accurate finite elements proposed in the technical literature, and also with analytical solutions: for the cases where such closed-form solutions were not available in the literature, they have been computed by exact integration of the governing differential equations. It is shown that the presented element is almost insensitive to both membrane- and shear-locking, and that such phenomena can be easily controlled by properly choosing the number of elements or the NURBS degree

Equilibria determination of elastic articulated duoskelion beams in 2D via a Riks-type algorithm

The overall behavior of an articulated beam structure constituted by elements arranged according to a specific chirality is studied. The structure as a whole, due to its slenderness and geometry, is called duoskelion beam. The name duoskelion is a neologism which is inspired by the Greek word δύοσκέλιον (two-legged). A discrete model for shearable beams, formulated recently, is exploited to investigate its mechanics. A purposely designed numerical scheme, adapting the Riks rationale, is used to calculate large displacement and deformation equilibria of duoskelion beams. Aimed at computing the current step correction, the Riks arc-length method is modified and made more efficient by applying a specific orthogonality condition, defined via the stiffness matrix, to an adapted extrapolation step. The robustness of the resulting scheme and its capability to follow equilibrium branches allows, in principle, for the exploration of the whole set of local energy minima in the introduced space of configurations, by using suitably modulated perturbative external loads. The developed numerical tool can be used to understand the mechanics of duoskelion beams. It is proved that there exists a stable principal equilibrium branch in which only compression is observed for any compression load. Additional stable equilibrium branches are found in compression such that the clamped–clamped compressed beam assumes a characteristic S shape which, upon reaching a critical load, is significantly amplified. A mechanically relevant stable equilibrium is also found in extension, being observed the S-shaped configuration experimentally found in Misra et al. (2020)

THE VALUE OF KNOWLEDGE THROUGH H-BIM MODELS: HISTORIC DOCUMENTATION WITH A SEMANTIC APPROACH

Abstract. The Building Information Modeling (BIM) in the Architectural Heritage field is constantly proving to be a fertile ground for the experimentation of innovative systems for the enhancement and management of cultural heritage. Regarding to the management of the entire process, the building field is increasing in efficiency from the construction to the management phase; conversely, the approach to historical buildings opens up interesting and heterogeneous scenarios, according to different levels of complexity. The presented work is the result of a collaboration between the Politecnico di Torino and the Escuela Técnica Superior de Arquitectura of Granada: the main scope was to create an historic building information model (H-BIM) of the building that today hosts the Faculty of Architecture (ETSAG), taking into account its historical past from the sixteenth century up to the present day, as the result of many modifications, extensions and different use classifications over time. According to this, the BIM methodology can be considered as a bridge between the archive documentation and the digital model, proving to be an effective tool as a data repository, semantically oriented, not only constituted by geometry, but also by alpha-numerical attributes, improving in effectiveness if it is directly related to formal language object oriented.</p

Grasp planning with a soft reconfigurable gripper exploiting embedded and environmental constraints

Grasping in unstructured environments requires highly adaptable and versatile hands together with strategies to exploit their features to get robust grasps. This paper presents a method to grasp objects using a novel reconfigurable soft gripper with embodied constraints, the Soft ScoopGripper (SSG). The considered grasp strategy, called scoop grasp, exploits the SSG features to perform robust grasps. The embodied constraint, i.e., a scoop, is used to slide between the object and a flat surface (e.g., a table or a wall) in contact with it. The fingers are first configured according to object geometry and then used to establish reliable contact with it. Given the object to be grasped, the proposed grasp planner chooses the best configuration of the fingers and the scoop based on the object point cloud and then suitably aligns the gripper to it

Concentration, stagnation and inequality: An agent-based approach

This paper presents a macroeconomic agent based model with endogenous innovation-driven growth and knowledge accumulation which aims to analyze the underlying causes of the recent increase in market concentration, by focusing on the interplay of technical change and market power, and the resulting macroeconomic consequences in terms of higher inequality and lower growth. The source of concentration lies in the fact that heterogeneous firms do not have equal access to capital-embodied innovations, as we assume that this depends on the “knowledge gap”, i.e., the difference between the degree of capital good's technical advancement and the firm's accumulated technological knowledge. The analysis shows that, in the absence of consistent knowledge spillovers and as long as capital goods remain considerably different from each other, technical progress generates systematic differences in productivity across firms, leading to a reallocation of market shares towards more productive firms. Consequently, as the newly-emerging large firms seek to translate the enhanced market power into higher mark-ups, the resulting shift in the income distribution from wages to profits eventually undermines aggregate demand and growth. Yet, simulation experiments reveal that the evolution of market concentration over time as well as its macroeconomic effects crucially depend on the presence (or lack thereof) of legal entry barriers, which, by influencing the process of diffusion of technological innovations, reinforce (or attenuate) the large firms’ ability to consolidate their dominant position and thus exploit their market power

Design of a tuned vbration absorber (TVA) for applications in transport engineering

The control of the response to tonal excitations or to broadband stochastic disturbances of a stiffened cylinder is investigated through the use of a Tuned Vibrating Absorber (TVA). In particular, the study considered both a purely passive device (Mechanical) and a semi-active one with shunt circuit (Electro-Mechanical) to evaluate the efficiencies and differences

A nonlinear Lagrangian particle model for grains assemblies including grain relative rotations

International audienceWe formulate a discrete Lagrangian model for a set of interacting grains, which is purely elastic. The considered degrees of freedom for each grain include placement of barycenter and rotation. Further, we limit the study to the case of planar systems. A representative grain radius is introduced to express the deformation energy to be associated to relative displacements and rotations of interacting grains. We distinguish inter‐grains elongation/compression energy from inter‐grains shear and rotations energies, and we consider an exact finite kinematics in which grain rotations are independent of grain displacements. The equilibrium configurations of the grain assembly are calculated by minimization of deformation energy for selected imposed displacements and rotations at the boundaries. Behaviours of grain assemblies arranged in regular patterns, without and with defects, and similar mechanical properties are simulated. The values of shear, rotation, and compression elastic moduli are varied to investigate the shapes and thicknesses of the layers where deformation energy, relative displacement, and rotations are concentrated. It is found that these concentration bands are close to the boundaries and in correspondence of grain voids. The obtained results question the possibility of introducing a first gradient continuum models for granular media and justify the development of both numerical and theoretical methods for including frictional, plasticity, and damage phenomena in the proposed model

Role of post mortem CT (PMCT) in high energy traumatic deaths

Background. Post Mortem Computed Tomography (PMCT) is being increasingly implemented in forensic field and could be an adjuvant to classic autopsies. In this study we evaluated the feasibility of complementation of conventional autopsy in trauma victims with PMCT. Materials and methods. A total of 21 subjects, who had sustained various types of blunt high-energy trauma, were selected from the casuistry of the Section of Legal Medicine at University of Pisa: before autopsy, a PMCT examination (Toshiba Aquilion 16 CT scanner) was performed, and after the acquisition of the raw images, MPR and VR reconstructions were performed with dedicated software. Results. PMCT is more sensitive than conventional autopsy in detecting skeletal injuries, whilst autopsy constitutes the method of choice for the detection of thoracic and abdominal visceral injuries. Conclusion. PMCT should be considered a useful tool in addition to conventional autopsy in evaluating trauma victims: it detects further bone fractures in body parts difficult to investigate during autopsy (i.e. posterior regions), facilitating the pathologist in the reconstruction of events and in determining the cause of death