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La presa del futuro
No full textVengono esaminate le problematiche della presa con robot, con riferimento all'evoluzione industriale degli ultimi anni. Sono quindi esaminate le esigenze attuali e le linee di sviluppo
A Proposal for Ensuring the Quality of Aerospace Engineering Higher Education in Europe
No full textThe paper presents a possible roadmap for the definition of a European quality label for aerospace related higher education degrees. The proposal is the result of a two-years long Horizon 2020 project that has involved a great portion of the European stakeholders in aerospace: Universities, research centres, industries (both small and large) networks, associations and accreditation agencies. The core concept established is that it is possible to establish a sector-specific, content based, quality system, that can complement the existing national or European accreditation systems, providing added value to the internal and/or external quality assurance processes that are in place in most EU countries. The tools and processes proposed are sufficiently simple to be manageable by Universities in addition to their national accreditation processes or as stand-alone assessment. The main goal of the proposed process is the evaluation of the quality of the aerospace curricula in the European context, whereas the accreditation of the programme can be seen as an optional extension of the process, subject to further national regulations. The process is proposed in view of the awarding of a sector-specific, content based, quality label, to be issued by an appropriate legally recognized and qualified institution. A set of 8 field tests with volunteering universities throughout Europe has been performed. They experienced the method as very practical and to the point
Multi-agent systems for production management in collaborative manufacturing
No full textThe paper aims to analyze multi-agent management structures in Small-Mid Enterprises (SME), such to investigate how collaborations among agents could be improved. A SME manager has generally to face with three issues: data management, organization of the production phases, interactions with mid-level management (denoted by "agents"). Data management is necessary in order to have a clear representation of the many types of data about products, orders and resources of the company. The organization of production phases consists on the management of the production process phases from design up to recycling. Based on a clear representation of the product life cycle, the manager will be able to organize the interactions between these agents (each one dedicated to handle a process phase) so as to facilitate the collaboration, and to make effective each mid-level management as far as it is concerned with controlling the operations to be carried out in each process phase. A model of the mid-layer multi-agent management negotiation, according to the "game theory" viewpoint, is proposed, and its main characters are analyzed, in view of its application
Influence of material optical characteristics on vision and fruition of Cultural Heritage
No full textFor Cultural Heritage materials is important to guarantee a correct conservation and vision of the artefacts, enhancing the observer experience assuring the best visual and conceptual appearance of artefacts. Several factors affect the visual appearance of artistic materials. However, available measurement methodologies for the material characterisation are not able to accurately predict the visual appearance of materials usually used in cultural heritage. Goals of the thesis research was to identify the visual attributes that mainly affect the appearance of artworks, investigate the correlation between measured data and visual human response and individuate if there are measured conditions that allow a better correlation. Finally, provide useful suggestion to aid in planning and selecting adequate conservative intervention, such as restoration work. In order to reach these purposes, different samples representative of materials used in artistic artefacts were selected and realised and two different visual testes were set up and carried out investigating the influence of lighting and viewing conditions on the human visual response of selected visual attributes: glossiness, colour (saturation), brightness and sparkling. The first visual test takes into account how the human visual responses on glossiness and saturation are affected by the lighting and viewing conditions using coloured samples with different levels of gloss obtained brushed on them different mixture of natural varnishes. While, in the second visual test were identified the elements that mainly affect the human perception of sparkling and brightness in monochromatic samples with mica particles, a mineral easily found in ornamental stones. At the end of each visual test, all responses were statistical analysed and, then, the results were compared with the corresponding objective measured data. In this way, it was possible to define what measurement conditions allow to have a better correlation with the subjective assessment
Transport models for risk assessment of natural and engineered nanoparticles in groundwater
No full textNanosized particles of several materials, such as TiO2, graphene, zero-valent iron, iron oxides, carbon nano-tubes, etc., are commonly used in industrial processes and for the manufacturing of commercial products. They can be released into the environment and, in particular, into groundwater throughout their entire life cycle, thus representing a potential risk for human health. Once released, nanoparticles can exhibit inherent toxicity, or play a role in enhancing the mobility of many contaminants, acting as a mobile solid phase which accelerates the transport of strongly sorbing contaminants (colloid-facilitated contaminant transport). It is therefore extremely important to develop approaches and tools suitable to predict the long-term fate of these emerging contaminants and the associated potential risk. The quantification of the toxic and carcinogenic risk towards potential receptors requires the application of transport models for the evaluation of the nanoparticle concentration at the exposition point, Cpoe. Nanoparticle transport in porous media is usually described by a modified advection-dispersion equation that takes into account the mass exchanges between liquid and solid phase due to physical and physico-chemical interactions. According to the degree of detail of the risk assessment procedure, Cpoe can be calculated via analytical formulations, Tier 2, or numerical tools, Tier 3. In this work, NP-specific transport models are simplified and adapted to the analytical solutions commonly adopted in the conventional Tier 2 RBCA approach. The analytical solutions commonly used for the calculation of dissolved contaminant Cpoe, are here extended to account for particle-porous-medium interaction. Moreover, the numerical tool MNM3D is proposed for the simulation of nanoparticle transport applied to Tier 3 risk assessment. MNM3D is a modified version of the well-known RT3D code, which implements numerical solutions to the NP transport equations porous media, accounting for the dependency of the attachment and detachment kinetic coefficients on transients in pore water ionic strength and velocity. The analytical solutions and the numerical code MNM3D are here both applied to a synthetic case of release of silver nanoparticles and the results are compared. Finally the same release in a more complex hydrogeological scenario is simulated using the MNM3D code to highlight the effects of hydrochemical heterogeneities on the long term fate of nanoparticles in the environment
The role of recirculation zones on non-Fickian transport phenomena in 3D porous media
No full textIn groundwater engineering, remediation techniques based on the injection of nano/particles have enjoined a particular success. Pore-scale numerical simulations are a powerful tool to study transport of solutes and colloidal suspensions in porous media, and are used to derive constitutive laws tune macro-scale models. In the Eulerian framework, the influence of the pore space geometry on transport phenomena was investigated thanks to computational fluid dynamics pore-scale simulations. Three different 3D periodic arrangements of spherical grains were used, namely face-centered-cubic (FCC), body-centered-cubic (BCC), and sphere-in-cube (SIC) packings, [1]. In Stokes regime, the transport of a conservative tracer and of particles undergoing instantaneous heterogeneous reaction were both investigated and the resulting outflow concentration (breakthrough curves) were analyzed: even if the porous media have the very same grains shape and size and the same porosity, the breakthrough curves present noteworthy differences, such as an enhanced tailing and early arrival times. The anomalous (non-Fickian) transport observed was indeed correlated with the peculiarities of the pore-space and to the presence of recirculation zones above all. The recirculation zones were detected at low Reynolds numbers and various methods, first of all a streaklines visualization, were adopted to describe qualitatively and quantitatively such zones. The analysis of the angle formed by velocity and vorticity vectors proved to be particularly effective in the detection of recirculation zones. At last, simulating the transport of particles undergoing instantaneous heterogeneous reactions, the role played by the medium structure is evident also evaluating the deposition efficiency coefficient, as its behavior clearly depends on the grains packing adopted. After more than fifty years, the study of anomalous transport in porous media still offers a breeding ground for researches in many different fields. Since in the groundwater framework the determination of this macro-scale parameter is a key factor to design effective remediation techniques, this work tries to exploit the potentiality of computational fluid dynamics to tackle the problem from the pore-scale, exploiting a practical approach
Measurement of weak non-linear response of Kevlar® fibre damaged by UV exposure
No full textThis paper deals with a high-sensitivity method for the assessment of damage in high-strength fibres exposed to UV radiation. A recently developed experimental testing machine, based on an optical measurement system and electro-magnetic driving force, was used to characterize fibre materials. Stiffness, damping, and non-linearity were measured on several Kevlar® fibre samples previously exposed to UV light for different lengths of time. The results show that UV radiation increases the material non-linearity by amounts which can be clearly observed even at low vibration amplitudes. On the contrary, uncertainties affecting the determination of stiffness and damping with the adopted approach don't seem to allow a similarly unambiguous UV damage assessment. Results confirm our initial hypothesis that non-linearity may be a valuable index of damage, at least in case of UV exposure, for applications in the Structural Health Monitoring (SHM) field
A probabilistic approach for the assessment of the influence of the dielectric constant of pore fluids on the liquid limit of smectite and kaolinite
No full textLiquid limit (LL) is defined as a limiting water content separating the viscous liquid state and plastic state of soil consistency. LL of clays, being a basic physico-chemical property, plays a role in environmental geotechnical engineering practice. Since it is well-known that kaolinite and smectite behave quite differently from each other from the geotechnical point of view, ninety-one data regarding smectite (Na and Ca) and kaolinite mixed with organic pore fluids having different dielectric constant (ε) values have been carefully analyzed. Data confirm that for a decreasing ε value of the pore fluid a decrease in LL is observed for the smectitic clays, with different magnitude depending on the main ion, whereas for kaolinitic clays this decreasing ε causes an increase in attractive forces causing flocculation and increase in LL values. A probabilistic approach has been performed to assess the robustness of the regression functions. For smectitic and kaolinitic clays the mathematical dependency of LL with ε is validated by the probabilistic analysis
Concrete pavement prediction life model based on electrical response of concrete-CNTs sensors under fatigue loading
No full textStructural Health Monitoring (SHM) of important infrastructures such as Portland cement concrete pavements plays a key role in pioneer societies, to guarantee the optimum usability and performance of the infrastructure system. As an example, this is imperative to appraise the destruction level in Portland cement concrete pavements along time as to plan their maintenance with proper actions at the right time. Based on this premise, the goal of this study is to extend an extensive feasibility study to set up a novel approach for SHM of Portland cement concrete pavements and remaining life estimation, based on self-sensing concrete-CNTs sensors added with multi-walled carbon nanotubes (CNTs). The concrete-CNTs sensors are applied as piezoresistive sensors (i.e. to collect information such as weight and species of passing vehicles), or as destruction identification sensors (i.e. to detect crack propagation in the Portland cement concrete pavement). For casting the concrete-CNTs sensors, some parameters are important, such as the number of CNTs, species of surfactant, dispersion quality etc. In this research, the dispersion quality of multi-walled carbon nanotubes in the aqueous phase and cement matrix was experiment examined using Ultraviolet-Visible Spectrophotometry (UV-VIS), Scanning Electron Microscopy (SEM) and mechanical experiments for compressive and flexural strength. The outcomes demonstrated that a new specific surfactant composition (sodiumdodecylbenzene sulfonate (SDS) and superplasticizer carboxylate base (SP-C) with the ratio of 1:9 respectively) could disperse MWCNTs around 64% more than other surfactant combinations indicated in the previous studies while this has enough compatibility with the concrete to omit antifoam in the mixing process and maintain the concrete mechanical specifications pretty constant. To appraise the influences of the main parameters affecting concrete-CNTs sensors function, diverse criteria in static and dynamic loading patterns were defined such as sensitivity of the sensor (Se), the standard deviation of the prediction error, repeatability (Re), cross-correlation (CC) and hysteresis (SSE). The dynamic criteria such as sensitivity, internal repeatability, cross-correlation and hysteresis declared that the dispersion energy levels for the dispersion of MWCNTs have a major impact on enhancing the function of the sensor rather than the number of CNTs. The repeatability criterion, contrariwise, showed that the number of MWCNTs has a major impact on the function of the sensor compared to the dispersion quality (dispersion energy level) of MWCNTs. Consequently, both parameters have to be regarded as relevant. The overall outcomes showed that the sensors fabricated with 0.15 wt% CNTs, superplasticizer and SDS as a surfactant using the maximum dispersion energy level (ultrasonic bath for 2 hours and 90 minutes of ultrasonic probing) have the best function in both static and dynamic load mode. To explore the influences of traffic loads on the pavement, concrete-CNTs sensors were experiment examined under various value of dynamic loads. The outcomes demonstrated that the maximum exterior load applied on the sensor (Fmax) is linearly correlated to the maximum response of the sensor (Smax) via a constant coefficient tagα/tagβ, in which tagα is defined as the slope of the Force vs. Time graph and tagβ is defined as the slope of the Sensor's response vs. Time curve. So, this can be concluded that the application of the indicated concrete-CNTs sensors for piezoresistive applications is feasible and the sensors can appraise the load with of high-goodness of fit (R2adj.> 0.99). In addition, to study the response of the concrete-CNTs sensor under the traffic loading, fatigue experiments were run. An alternative data processing log(G)-log(N) was applied instead of traditional S-log(N) fatigue graphs (Goodman curves), based on the electrical sensor response with a linear regression approach and the outcomes were verified by statistical tests. In this research, the concept of G has been defined for the first time as the slope of a sensor's response that reflects the destruction created in a pavement because of one pass of vehicle load. Based on these findings, two various types of remaining life models for Portland cement concrete pavements were proposed