Abstract
At Mount Etna volcano, the focus point of persistent tectonic extension is represented by the Summit Craters. A muographic telescope has been installed at the base of the North-East Crater ...from August 2017 to October 2019, with the specific aim to find time related variations in the density of volcanic edifice. The results are significant, since the elaborated images show the opening and evolution of different tectonic elements; in 2017, a cavity was detected months before the collapse of the crater floor and in 2018 a set of underground fractures was identified, at the tip of which, in June 2019, a new eruptive vent started its explosive activity, still going on (February, 2020). Although this is the pilot experiment of the project, the results confirm that muography could be a turning point in the comprehension of the plumbing system of the volcano and a fundamental step forward to do mid-term (weeks/months) predictions of eruptions. We are confident that an increment in the number of telescopes could lead to the realization of a monitoring system, which would keep under control the evolution of the internal dynamic of the uppermost section of the feeding system of an active volcano such as Mount Etna.
Rotator cuff (RC) injury is a common pathology that involves the tearing and weakening of the muscles and tendons that make up RC. Rehabilitation after surgery is crucial for recovery and restoring ...range of motion (ROM). Currently, the assessment of a patient's improvement relies on subjective evaluations by physicians. To objectively evaluate the patient recovery, motion capture (MOCAP) systems can be used in this scenario. However, MOCAP requires extremely structured environments and specialists. To overcome this issue, the combined use of flexible sensors with 3-D printing techniques has been proposed. This solution will allow developing highly performant wearables with a reduced encumbrance, easy to use, and compliant with the human skin. In this study, we exploited the advantages of fiber Bragg gratings (FBGs) combined with those of 3-D printing to propose a transformative approach in the field of wearables for shoulder monitoring. First, the 3-D-printed sensor was designed and fabricated using thermoplastic polyurethane as printing filament to make the system flexible. One of the main novelties relies on the direct integration of the anchorage mechanism (two extensible elements) during printing. To the best of our knowledge, this is one of the first works in which this approach is proposed. Then, the sensor was metrologically assessed to investigate its sensitivity to strain and temperature and the hysteresis error. Finally, a preliminary assessment on a healthy volunteer was proposed to assess the system capability of monitoring shoulder flexion-extension movements with different ROMs and movement rates in the sagittal plane showing promising results.
•A Liquid Rubber (LR) is presented as solution to overcome common issues of asphalt rubber binders.•LR-bitumen blends are manufactured at several temperatures and with various modifier contents.•High ...temperature rheology, service temperature properties and storage stability are assessed.•Analysis includes a comparison with a neat bitumen and a SBS modified bitumen.•Results show that liquid rubbers could represent a breakthrough within the bitumen industry.
The addition of crumb rubber particles as bitumen modifier can be currently considered as a well-established alternative to conventional polymers for bitumen modification. However, Recycle Tyre Rubber (RTR) modified binders still present drawbacks such as poor mix workability and hot storage stability. Within this study the authors try unlocking the full potential of devulcanised tyre rubber-heavy oils blend, named Liquid Rubber (LR), by exploring the possibility of tailoring recycled polymer modified bitumen with unconventional high-content of RTR and designed to overcome the above mentioned technological problems of RTR modified bitumen while keeping its advantages. Results show that LR-bitumen blends incorporating up to 30% RTR in weight of total binder clearly improves useful temperature interval of base bitumen by maintaining solubility values allowing them to be considered stable at hot-storage temperature. Furthermore, the LR modifier allows reducing usual manufacture temperatures up to 30 °C by providing superior low and intermediate temperature rheology, however high service temperature properties are improved only at low strain.
Fiber Bragg gratings (FBGs) are known for their uses in applications ranging from civil engineering to medicine. A bare FBG is small and light; hence, it can be easily embedded into hosting ...materials. However, conventional fabrication methods are generally time-consuming with reproducibility issues. A more recent strategy has been proposed to develop novel FBG-based systems by encapsulating the grating within 3-D-printed structures. This process, known as 3-D printing, is characterized by several advantages like rapid prototyping, printing precision, and high customization. The possibility of quickly personalizing the 3-D-printed sensors by customizing the infill settings makes this technique very appealing for medical purposes, especially for developing smart systems. However, the influence of printing settings on the sensor response has not been yet systematically addressed. This work aimed at combining FBG with the most popular 3-D printing technique (the fused deposition modeling FDM) to develop four 3-D-printed sensors with different printing profiles. We chose two patterns (triangle and gyroid) and two infill densities (30% and 60%) to investigate their influence on the sensors’ response to strain, temperature, and relative humidity (RH), and on the hysteresis behavior. Then, we preliminary assess the sensor performance in a potential application scenario for FBG-based 3-D printing technology: the cardiorespiratory monitoring. The promising results confirm that our analysis can be considered the first effort to improve the knowledge about the influence of printing profiles on sensor performance and, consequently, pave the way to develop highly performant 3-D-printed sensors customized for specific applications.
AbstractThis paper shows and compares the experimental results obtained by using a standard cone (10 cm2) and a mini piezocone (2 cm2). Tests were carried out at Calendasco (Piacenza, Italy) in a ...natural soil deposit mainly consisting of clayey-sandy silts. Grain size distribution with depth was also available. Other tests were carried out at Cavezzo (Modena, Italy), where liquefaction-induced phenomena were observed during the May 29, 2012, seismic sequence. The purpose was to investigate capabilities and limitations of mini piezocone and to explore the possibility of obtaining a better prediction of soil stratigraphy in thin layered deposits. Systematic differences in terms of tip resistance and sleeve friction were not observed, even though, generally, qc standard <qc mini. The spatial heterogeneity was considered responsible of the higher observed differences. In both test sites thin sandy layers are characterized by Ic mini ≤Ic standard, with a ratio of the Ic index as low as 0.88. This allows us to conclude that the minicone could be a valid alternative to the standard in identifying thin sandy layers.
The Pierre Auger Observatory is undergoing a major upgrade named AugerPrime with the primary aim to add sensitivity to the mass-composition discrimination of ultrahigh-energy cosmic rays. Two ...different photomultipliers will be added to each water-Cherenkov station of the surface detector of Observatory. To achieve the scientific goals of AugerPrime these photomultipliers have to ensure a linear response to input-light in a wide range. This paper describes a system developed for the validation of AugerPrime-photomultipliers.
•Background on viscosity measurements and CFD studies on mixing complex fluids.•Laboratory tests provide visual proves of enhanced mixing efficiency with DHI.•CFD models validated the empirical ...calibration with single phase fluids.•CFD simulations compared well with experimental results.•CFD clarifies reasons behind the improved rheometry of complex fluids with DHI.
Multi-phase materials are common in several fields of engineering and rheological measurements are intensively adopted for their development and quality control. Unfortunately, due to the complexity of these materials, accurate measurements can be challenging. This is the case of bitumen-rubber blends used in civil engineering as binders for several applications such as asphalt concrete for road pavements but recently also for roofing membranes. These materials can be considered as heterogeneous blends of fluid and particles with different densities. Due to this nature the two components tends to separate and this phenomenon can be enhanced with inappropriate design and mixing. This is the reason behind the need of efficient dispersion and distribution during their manufacturing and it also explains while real-time viscosity measurements could provide misleading results. To overcome this problem, in a previous research effort, a Dual Helical Impeller (DHI) for a Brookfield viscometer was specifically designed, calibrated and manufactured. The DHI showed to provide a more stable trend of measurements and these were identified as being “more realistic” when compared with those obtained with standard concentric cylinder testing geometries, over a wide range of viscosities. However, a fundamental understanding of the reasons behind this improvement is lacking and this paper aims at filling these gaps. Hence, in this study a tailored experimental programme resembling the bitumen-rubber system together with a bespoke Computational Fluid Dynamics (CFD) model are used to provide insights into DHI applicability to perform viscosity measurements with multiphase fluids as well as to validate its empirical calibration procedure. A qualitative comparison between the laboratory results and CFD simulations proved encouraging and this was enhanced with quantitative estimations of the mixing efficiency of both systems. The results proved that CFD model is capable of simulating these systems and the obtained simulations gave insights into the flow fields created by the DHI. It is now clear that DHI uses its inner screw to create a vertical dragging of particles within a fluid of lower density, while the outer screw transports the suspended particles down. This induced flow helps keeping the test sample less heterogeneous and this in turns allows recording more stable viscosity measurements.
This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) grant number EP/M506588/1.
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•This study provides the technical information allowing each laboratory to independently design, manufacture and use their own dual helical ribbon impeller.•This geometry has been ...shown to be the most suitable to enhance mixing efficiency of highly heterogeneous fluids to be characterized by means of rotational viscometers.•The calibration was carried out by using the widest range of Newtonian and non-Newtonian fluids by adopting the Rieger-Novak approach.•Implementing its use within the road paving material science allowed obtaining more realistic viscosity measurements of highly heterogeneous asphalt binders.
Road bituminous binders are becoming more complex since, to enhance properties and/or engineer circular economy, the conventional binder is enriched with modifiers of different nature giving birth to a final-product recognisable as highly heterogeneous fluid. The assessment of these materials relies on rheological measurements; however, existing testing equipment are designed for homogeneous fluids, proving to be often inadequate. In fact, rotational testing lacking mixing efficiency during measurements, can compromise sample stability, resulting in non-representative results Lo Presti et al. (2014). To address these challenges, a dual helical ribbons (DHR) was purposefully created and successfully employed in prior studies to measure the rotational viscosity of highly heterogeneous asphalt materials Giancontieri et al. (2019). While the DHR effectiveness has been extensively discussed in earlier investigations, this study aims to contribute to the scientific community at large by providing: state-of-the-art on improving mixing efficiency of highly heterogeneous fluids, rationalizing the choice of the DHR geometry comprehensive technical details for realising any DHR, verified through numerical modelling Calibration with model input parameters achieved by adopting the Rieger and Novak method, and finally design validation. The authors aim for the broader material science community to benefit from this investigation, enabling technologists to independently develop DHR devices and explore new applications.
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