1,720,970 research outputs found
UV-curable coatings for energy harvesting applications: Current state-of-the-art and future perspectives
No full textGenerally speaking, energy harvesting is an up-to-date technology that describes the possibility of capturing small amounts of energy (thermal, solar, or mechanical) from the surroundings and storing them as electrical energy for later uses when needed. Among the energy harvesting systems, the use of piezoelectric thin films and coatings is gaining increasing interest from both the academic and industrial communities, as these systems allow for the design and development of micro- and nano-scale devices, thanks to the possibility of being micromachined and to the added functionality offered by the electromechanical coupling. These peculiarities justify their use for different applications, ranging from high energy density harvesters to high sensitivity sensors, and even low power consumption and large displacement actuators. Further, the current focus of the research on piezoelectric energy harvesting coatings is shifting from fully inorganic to hybrid organic-inorganic (i.e., composite) systems, as the latter can offer higher flexibility (i.e., lower stiffness), making them more sensitive to small vibrations and therefore suitable for these specific harvesting conditions. In this regard, photoinduced polymerization (the so-called "UV-curing") has become a suitable and reliable technique for the manufacturing of piezoelectric composite systems, as it is a solvent-free approach that allows for transforming a liquid mixture of monomers/oligomers into a solid 3D network in a few seconds, with a very limited energy consumption and a very high conversion. Besides, as the UV-curing process is very fast, the dispersed ceramic piezoelectric phase is not prone to settle down in the liquid resin, hence ensuring its homogeneous distribution within the polymer network after curing and better piezoelectric performance. The present review aims to provide the reader with an up-to-date overview of UV-curable coatings for piezoelectric energy harvesting purposes, highlighting their potential and piezoelectric features; further, some perspectives about possible future developments will be proposed
Influence of Mechanical Properties on the Piezoelectric Response of UV-Cured Composite Films Containing Different ZnO Morphologies
No full textZnO flower-like (ZFL) and needle (ZLN) structures were synthesized and embedded into UV-curable acrylic resin (EB), with the aim to study the effect of filler loading on the piezoelectric properties of the resulting composite films. The composites showed uniform dispersion of fillers within the polymer matrix. However, by increasing the filler amount, the number of aggregates increased, and ZnO fillers appeared not to be perfectly embedded in polymer film, indicating poor interaction with acrylic resin. The filler content increase caused an increase in glass transition temperature (T-g) and a decrease in storage modulus in the glassy state. In particular, compared with pure UV-cured EB (T-g = 50 degrees C), 10 wt.% ZFL and ZLN presented T-g values of 68 and 77 degrees C, respectively. The piezoelectric response generated by the polymer composites was good when measured at 19 Hz as a function of the acceleration; the RMS output voltages achieved at 5 g were 4.94 and 1.85 mV for the composite films containing ZFL and ZLN, respectively, at their maximum loading levels (i.e., 20 wt.%). Further, the RMS output voltage increase was not proportional to the filler loading; this finding was attributable to the decrease in the storage modulus of the composites at high ZnO loading rather than the dispersion of filler or the number of particles on the surface
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between INRIM (Italy) and the BIPM
Full text linkUsing of High Precision Multimeter Digitizer for High Transient Current Calibration
No full textThe calibration of transient current sensors is
fundamental for the reliability of high current, short-circuit tests.
The test can be performed with prospective or withstand current,
but in both cases, the dynamic behavior of the current sensors
has to be investigated, due to his influence on the scale factor
value. The requirements of the IEC 62475 standard can be
achieved with a calibration in transient conditions, performed
with an approved reference measuring system. In this work a
most performance measuring system is presented, for the
improvement of INRIM high transient current measuring
capability
THE IEN CCC BRIDGE TO SCALE THE QUANTIZED HALL RESISTANCE
No full textA cryogenic current comparator bridge, to scale from the quantised Hall resistance to 1 Ω, has been built at IEN. A description is given and preliminary results are reporte
Influence of different dry-mixing techniques on the mechanical, thermal, and electrical behavior of ultra-high molecular weight polyethylene/exhausted tire carbon composites
No full textThe mechanical, thermal, and electrical behavior of ultra-high molecular weight (UHMWPE) composites containing different amount of pyrolyzed exhausted tire carbon (ETC) is investigated. Composites were obtained by dry-mixing the powders with a homogenizer and an impact mill. The results clearly indicate that, by changing the mixing method, it is possible to tune the rheological and morphological characteristics of the composites and in turn their mechanical, thermal, and electrical properties. Better performances were observed for the composites obtained with the impact mill, which showed improved Young modulus, reduced electrical and thermal resistance with respect to those of homogenized counterparts. All the composites exhibited a relevant reduction of electrical resistivity with a percolation threshold of 1.51 vol%
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