Il proemio di Theocr. 17 e Simon. IEG2 fr. 11 W.: eroi, discendenti di semidei

Defining heroes as ‘descended from demigods’, Theocritus (17.5) seems to have in mind the Simonidean phrase ἡμιθέων ὠκύμορον γενεήν (fr. 11.17 West2), while slightly changing its meaning. On a broader level, Simonides’ elegy appears to be Theocritus’ main model for the proem of his Encomium of Ptolemy Philadelphus

Design and Modelling of Wireless Power Transfer and Energy Harvesting Systems

The escalation of the Internet-of-Everything topicality has motivated an increased interest in both academia and industry research for efficient solutions enabling self-sustained smart operations. From the maintenance point of view, indeed, battery-less strategies represent the most valuable way for distributed zero-power standalone electronics. With this purpose, different scavenging techniques are being adopted, gathering energy from different sources such as mechanical, solar, thermal and electromagnetic waves. Due to the wide spread of wireless communication systems, the latter technology has recently benefited a renewed interest. This Ph.D. research activity has been focused on the investigation of new efficient solutions for radiofrequency energy harvesting and wireless power transmission techniques, aiming at improving the state of the art, by also taking into account the imperative necessity of eco-friendly materials for the development of green electronics. The combination of radiofrequency energy harvesting and ultra-wideband techniques is also proposed as possible candidate for future RFID systems. These functionalities are integrated in a novel, compact and low-profile tag, whose details are provided thoroughly from both electromagnetic and nonlinear circuit viewpoints. Results validation is provided through experimental characterization. Compatibility with the environment is assured by implementation with recyclable material. This concept is then extended with the investigation of more elaborated energy scavenging architectures, including rectenna arrays. Finally, a near-field wireless power transmission system is presented on low-cost materials, therefore suitable for possible mass-market deployment

New insights on homogenization for hexagonal-shaped composites as Cosserat continua

In this work, particle composite materials with different kind of microstructures are analyzed. Such materials are described as made of rigid particles and elastic interfaces. Rigid particles of arbitrary hexagonal shape are considered and their geometry is described by a limited set of parameters. Three different textures are analyzed and static analyses are performed for a comparison among the solutions of discrete, micropolar (Cosserat) and classical models. In particular, the displacements of the discrete model are compared to the displacement fields of equivalent micropolar and classical continua realized through a homogenization technique, starting from the representative elementary volume detected with a numeric approach. The performed analyses show the effectiveness of adopting the micropolar continuum theory for describing such materials

Co-Design Strategies for Energy-Efficient UWB and UHF Wireless Systems

This paper reviews the most recent methods, combining nonlinear harmonic-balance-based analysis with electromagnetic (EM) simulation, for optimizing, at the circuit level, modern radiative RF/microwave systems. In order to maximize the system efficiency, each subsystem must be designed layoutwise, accounting for the presence of the others, that is, accounting for its actual terminations, rather than the ideal ones (50 Ω). In this way, the twofold goal of minimizing size and losses of the system is obtained by reducing intersystem matching networks. Indeed, terminations are complex, frequency-dispersive, and variable with the signal level, if active operations are concerned, and are responsible for performance degradation if not properly optimized. This approach is nowadays necessary, given the ever increased spread of pervasively distributed RF microsystems adopting miniaturized antennas, such as radio frequency identification (RFID) or wireless sensor networks, that must be low-cost, low-profile, low-power, and must simultaneously perform localization, identification, and sensing. For the design of a transmitter and a receiver connected with the respective antennas, suitable figures of merit are considered, encompassing radiation and nonlinear performance. Recent representative low-profile realizations, adopting ultra-wideband (UWB) excitations are used to highlight the benefit of the proposed nonlinear/EM approach for next generation energy autonomous microsystem, such as UWB-RFID tags

walk through programming for industrial applications

Abstract Collaboration between humans and robots is increasingly desired in several application domains, including the manufacturing domain. The paper describes a software control architecture for industrial robotic applications allowing human-robot cooperation during the programming phase of a robotic task. The control architecture is based on admittance control and tool dynamics compensation for implementing walk-through programming and manual guidance. Further steps to integrate this system on a real set-up include the robot kinematics and a socket communication that sends a binary file to the robot

Cross-calibration of eight-polar bioelectrical impedance analysis versus dual-energy X-ray absorptiometry for the assessment of total and appendicular body composition in healthy subjects aged 21-82 years.

Aim: To calibrate eight-polar bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) for the assessment of total and appendicular body composition in healthy adults.Research design: A cross-sectional study was carried out.Subjects: Sixty-eight females and 42 males aged 21-82 years participated in the study.Methods: Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by DXA; resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz; whole-body resistance was calculated as the sum R of arms, trunk and legs.Results: The resistance index (RI), i.e. the height(2)/resistance ratio, was the best predictor of FFM and appendicular LTM. As compared with weight (Wt), RI at 500 kHz explained 35% more variance of FFM (R-adj(2) =0.92 vs 0.57), 45% more variance of LTMarm (R-adj(2) = 0.93 vs 0.48) and 36% more variance of LTleg (R-adj(2) = 0.86 vs 0.50) (p < 0.001 for all). The contribution of age to the unexplained variance of FFM and appendicular LTM was nil or negligible and the RI x sex interactions were either not significant or not important on practical grounds. The percent root mean square error of the estimate was 6% for FFM and 8% for LTMarm and LTMleg.Conclusion: Eight-polar BIA offers accurate estimates of total and appendicular body composition. The attractive hypothesis that eight-polar BIA is influenced minimally by age and sex should be tested on larger samples including younger individuals

Fabrication of three terminal devices by ElectroSpray deposition of graphene nanoribbons

Electrospray deposition (ESD) in ambient conditions has been used to deposit graphene nanoribbons (GNRs) dispersed in liquid phase on different types of substrates, including ones suitable for electrical transport. The deposition process was controlled and optimized by using Raman spectroscopy, Scanning Probe Microscopies and Scanning Electron Microscopy. When deposited on graphitic electrodes, GNRs were used as semi-conducting channel in three terminal devices showing gate tunability of the electrical current. These results suggest that ESD technique can be used as an effective tool to deposit chemically synthesized GNRs onto substrates of interest for technological applications

Splitting of multiple hydrogen molecules by bioinspired diniobium metal complexes: a DFT study

Splitting of molecular hydrogen (H2) into bridging and terminal hydrides is a common step in transition metal chemistry. Herein, we propose a novel organometallic platform for cleavage of multiple H2 molecules, which combines metal centers capable of stabilizing multiple oxidation states, and ligands bearing positioned pendant basic groups. Using quantum chemical modeling, we show that low-valent, early transition metal diniobium(II) complexes with diphosphine ligands featuring pendant amines can favorably uptake up to 8 hydrogen atoms, and that the energetics are favored by the formation of intramolecular dihydrogen bonds. This result suggests new possible strategies for the development of hydrogen scavenger molecules that are able to perform reversible splitting of multiple H2 molecules

Early Literacy Skills and Later Reading and Writing Performance Across Countries: The Effects of Orthographic Consistency and Preschool Curriculum

Background Studies have reported a strong association between children's early literacy skills at preschool and their reading and writing skills at primary school. However, it is unclear whether this association is affected by language and curriculum practices. Objective The study investigates (i) whether early literacy skills are influenced by orthographic consistency and by preschool curriculum, and (ii) how early skills are related to later literacy skills across countries. Method Three countries, Italy (n = 73), Romania (n = 65), and Belgium (n = 109) were involved in the study, for a total of 247 children. Language and early literacy in preschool were assessed using a novel assessment tool (the ‘Talk’). Early visual-phonological and manual aspects integration were investigated using rapid automatized naming and grapho-motor tasks. The children’s reading and writing skills nine months later were assessed using standardized tests. Results Results showed higher early literacy scores for the groups of children speaking languages with more transparent orthographic systems and for the group taking part in preschool activities designed to enhance literacy acquisition. Later reading and writing skills were predicted by early competences, albeit with differences across countries. Conclusions Findings suggest that literacy acquisition trajectories are not only associated with early skills but are also influenced by language characteristics and curriculum practices. The study also presents preliminary findings relative to the ‘Talk’, an assessment tool that may have important implications for early identification and intervention of language and literacy difficulties, as well as for improving cross-country curriculum practices

Hydrogenated Benzene in Circumstellar Environments: Insights into the Photostability of Super-hydrogenated PAHs

Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C6H6) rings, emit infrared radiation (3–12 μm) due to the vibrational transitions of the C–H bonds of the aromatic rings. The 3.3 μm aromatic band is generally accompanied by the band at 3.4 μm assigned to the vibration of aliphatic C–H bonds of compounds such as PAHs with an excess of peripheral H atoms (Hn–PAHs). Herein we study the stability of fully hydrogenated benzene (or cyclohexane, C6H12) under the impact of stellar radiation in the photodissociation region (PDR) of NGC 7027. Using synchrotron radiation and time-of-flight mass spectrometry, we investigated the ionization and dissociation processes at energy ranges of UV (10–200 eV) and soft X-rays (280–310 eV). Density Functional Theory (DFT) calculations were used to determine the most stable structures and the relevant low-lying isomers of singly charged C6H12 ions. Partial Ion Yield (PIY) analysis gives evidence of the higher tendency toward dissociation of cyclohexane in comparison to benzene. However, because of the high photoabsorption cross-section of benzene at the C1s resonance edge, its photodissociation and photoionization cross-sections are enhanced, leading to a higher efficiency of dissociation of benzene in the PDR of NGC 7027. We suggest that a similar effect is experienced by PAHs in X-ray photon-rich environments, which ultimately acts as an auxiliary protection mechanism of super-hydrogenated polycyclic hydrocarbons. Finally, we propose that the single photoionization of cyclohexane could enhance the abundance of branched molecules in interstellar and circumstellar media