Development of n-DoF Preloaded structures for impact mitigation in cobots

A core issue in collaborative robotics is that of impact mitigation, especially when collisions happen with operators. Passively compliant structures can be used as the frame of the cobot, although, usually, they are implemented by means of a single-degree-offreedom (DoF). However, n-DoF preloaded structures offer a number of advantages in terms of flexibility in designing their behavior. In this work, we propose a comprehensive framework for classifying n-DoF preloaded structures, including one-, two-, and threedimensional arrays. Furthermore, we investigate the implications of the peculiar behavior of these structures-which present sharp stiff-to-compliant transitions at designdetermined load thresholds-on impact mitigation. To this regard, an analytical n-DoF dynamic model was developed and numerically implemented. A prototype of a 10DoF structure was tested under static and impact loads, showing a very good agreement with the model. Future developments will see the application of n-DoF preloaded structures to impact-mitigation on cobots and in the field of mobile robots, as well as to the field of novel architected materials

BRDF characterization of Al-coated thermoplastic polymer surfaces

In this paper, we present a combined morphological and optical characterization of aluminum-coated thermoplastic polymer surfaces. Flat plastic substrates, obtained by means of an injection molding process starting from plastic granules, were coated with ultra-thin aluminum films evaporated in vacuo, on top of which a silicon-based protective layer was plasma deposited in order to prevent oxidation of the metal reflective surface. Different sample treatments were studied to unravel the influence of substrate chemistry, substrate thickness, aluminum and protective layer thickness, and surface roughness on the actual optical reflectance properties. Bidirectional reflectance distribution function measurements, corroborated by surface morphological information obtained by means of atomic force microscopy, correlate reflectance characteristics with the root-mean-square surface roughness, providing evidence for\ua0the role of the substrate and the thin films\u2019 morphology. The results unravel information of interest within many applicative fields involving metal coating processes of plastic substrates as an example in the case of automotive lighting

nanoscale characterisation of hybrid photovoltaic cells based on c61 capped cdse qds

Hybrid solar cells based on 1,2 methanofullerene (C61) capped CdSe and poly (3-hexylthiophene) (P3HT) were been investigated through a range of techniques. High resolution transmission electron microscopy (HRTEM) was used to characterize size, morphology and crystal structure of as-grown and C61-capped CdSe quantum dots. Cross sectional lamellar specimens were prepared from full photovoltaic devices using a focused ion beam milling approach. The sections were analysed by high angle annular dark field imaging in scanning TEM mode to determine the morphology of the device, in particular the intermixing of P3HT and capped quantum dots

Comparing the Prevalence of Polypharmacy and Potential Drug-Drug Interactions in Nursing Homes and in the Community Dwelling Elderly of Emilia Romagna Region

Backround: We aimed at assessing the prevalence of polypharmacy and potential drug-drug interactions (DDIs) with clinical relevance in elderly patient on Emilia Romagna area. Both outpatients and residents in nursing homes were assessed, with only partially overlapping strategies. Methods: We defined a list of 190 pairs of potentially interacting drugs, based on literature appraisal and availability of therapeutic alternatives. January-June 2018 data on drug use in patients over 65 years-old were collected from nine Local Health Authorities of Emilia Romagna: data on community-dwelling subjects were extracted from archives of reimbursed prescriptions, while drug use in a sample of nursing homes was recorded from clinical charts in one index day within the same semester. The frequency of polypharmacy (at least five or at least 10 concurrent drugs) and of each DDI was calculated. Results: In line with different rates of polypharmacy (80% vs 16%), the risk of exposure to at least one interaction was 53.7% in nursing homes and 26.4% in outpatients. Among DDIs, in nursing homes antidepressants—anxiolytics (11.9%) ranked first, followed by antidepressants—aspirin (7.4%). In outpatients, ACE-inhibitors—non-steroidal anti-inflammatory drugs (NSAIDs) reached 7.2% followed by the calcium channel blockers—α-blockers (2.4%). Discussion: Polypharmacy and risk of DDIs appeared very different in the two settings, due to both technical and clinical reasons. In order to reduce use of benzodiazepines, NSAIDs, antidepressants and relevant DDIs, 1) defining alternative options for pain relief in elderly outpatients, and 2) implementing non-pharmacological management of insomnia and anxiety in nursing homes should be prioritized

Modeling the total cost of ownership of an electric car using a residential photovoltaic generator and a battery storage unit-an Italian case study

As electric vehicles gain acceptance, an increasing number of households consider the possibility of buying the bundle including an electric car, a photovoltaic system, and a battery storage unit. Apart from the attractive environmental benefits, a relevant uncertainty concerns the economic convenience of such a choice. Since many variables play a role, we set up a total cost of ownership model to evaluate whether, and under which conditions, the bundle is cost-competitive relative to buying an electric car only (and charging it from the electrical grid) or a conventional combustion engine car. By combining, for the first time, such an economic model with an energy model and a driving profile model, we find that the degree of electricity self-production used to charge the electric car might be very high, varying from 90% to 62%, depending on the annual distance traveled. The cost of such electricity varies widely and can be lower than the grid electricity price when fiscal incentives are available and for long annual distances traveled. A smart charging practice based on both economic factors and weather forecast can greatly enhance self-sufficiency, i.e., independence from the electrical grid. We estimate that, given the current Italian financial incentives, 10,000 km/year are needed to make the electric car cost-competitive with respect to an equivalent petrol-fueled one. Such threshold increases to more than 25,000 km/year if financial incentives are removed

3D-printed poly(oxymethylene): Improving printability via PMMA sacrificial substrates and characterization of the mechanical and thermal properties

The fabrication of poly(oxymethylene) by means of additive manufacturing is still a problematic procedure due to the low adhesion with standard printing plates and extended warping. The use of polymers as alternative substrates is an effective way, especially if their glass-transition temperature is below the processing temperatures. Using poly(methyl methacrylate) sheets as sacrificial substrate, standard samples of poly(oxymethylene) are successfully printed, a result achieved in the past only by means of expensive and complex equipment. Furthermore, the mechanical and thermal properties of poly(oxymethylene) upon UV aging up to 500 h are investigated. Our results demonstrate that aging of 3D-printed poly(oxymethylene) causes chain scission and weakening of intermolecular bonds, crystallization of part of the amorphous areas, and results in the embrittlement of the material. The intermolecular structure of poly(oxymethylene) has been investigated by means of Fourier transform infrared spectroscopy

Explicit empirical model for photovoltaic devices. Experimental validation

4siA comparison between the experimental current-voltage (I-V) and power-voltage (P-V) characteristics of PhotoVoltaic (PV) modules, and the prediction of an explicit empirical model has been carried out. The model consists of an explicit expression for the current as a function of the voltage; the only inputs are the parameters that are always directly available in the manufacturer’s datasheet. The comparison was carried out on four representative PV technologies, based on polycrystalline Si, Heterojunction with Intrinsic Thin layer (HIT), Copper Indium Gallium Selenide (CIGS), and Cadmium Telluride (CdTe). The comparison reveals that the model replicates the experimental I-V and P-V curves to a very good degree of accuracy for the considered operating conditions and PV technologies. This validation sets a turning point in PV modelling, as it enables a reliable use of this accessible model.openembargoed_20190608Massi Pavan, A.; Vergura, S.; Mellit, A.; Lughi, V.MASSI PAVAN, Alessandro; Vergura, S.; Mellit, A.; Lughi, Vann

XSG-based control scheme for a grid-connected hybrid generation system

This paper presents a control scheme for the optimization of the efficiency of a grid-connected hybrid generation system consisting of a photovoltaic generator and a wind turbine. The design of the control system is made using a Xilinx System Generator tool that allows the future implementation of the code in a Field-Programmable Gate Array board. An online-trained Artificial Neural Network-based control scheme has been used in order to improve the performance of the classical control algorithms. A recurrent Elman Neural Network and a Feed Forward Neural Network have been chosen in order to maximize the power produced by the two renewable energy-based sources. Furthermore, the supervision of the grid-connected inverter is ensured by means of a traditional Voltage Oriented Control scheme. The simulation results, that have been obtained in a Matlab/Simulink environment, prove the effectiveness and the accuracy of the developed control system