Materials Literature
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This paper will introduce innovative technologies for partial discharge (PD) measurements, trying to answer to the common question that is associated with PD detection, that is, its effectiveness regarding fundamental items for asset management as risk assessment and maintenance planning. To this aim, the application…
Electrical treeing in polymeric insulation is potentially a nano-structure dependent phenomenon. The present work is part of a preliminary study on electrical treeing in EVA-layered silicate nanocomposites having different morphology. Two parameters have been mainly considered: the treeing inception voltage (TIV) and…
Does the quasi–one-dimensional titanium pyroxene NaTiSi 2 O 6 exhibit the novel orbital-assisted Peierls state? We calculate its groundstate properties by three methods: Monte Carlo simulations, a spin-orbital decoupling scheme and a mapping onto a classical model. The results show univocally that for the spin and orb…
The turmoil of activities that has surrounded nanotechnology in recent years continued to grow and outburst in several directions. This has reflected as well in the field of nanodielectrics where a great number of contributions resulted, a progress that the authors will comment. This annotated appreciation will be dev…
Stress grading coatings of cable and coil terminations are considerably affected by the high dV/dt present in PWM voltage source converters. As repetitive steep transients can result in the development of hot spots and enhanced electric fields in the stress grading (SG) system, premature failures of power apparatus ca…
Helical polymers often exhibit pronounced chirality recognition during crystallization. By molecular dynamics simulation, we have already shown that the helical polymers crystallize with or without marked chirality selection depending on structural details of the polymer molecules. We have there classified the helical…
The photoabsorption and photoluminescence (PL) properties of the surface E(') center, -GeX(3), and the combined E(')-center-oxygen vacancy, X(3)Ge-GeX(2), defects in substoichiometric germanium oxides have been investigated by high-level ab initio calculations, including complete active space self-consistent field, mu…
This chapter contains sections titled: Introduction, Scope and Nomenclature Theoretical Considerations Preparative Chemistry and Properties Conclusion Acknowledgment References
Several research groups worldwide have now been able to document some significant improvements that can be made in the electrical, and other, properties of polymer composites through the incorporation of nanoparticulates. Although it is now becoming clear that the mechanisms responsible for these changes are by no mea…
Femtosecond transient absorption spectroscopy was applied to map out the electronic transition energies of a selected semiconducting zigzag carbon nanotube, the (11,0) tube. The experiment was performed by resonant excitation of the lowest electronic transition with spectrally narrow pump pulses, ensuring predominant…
Partial discharge (PD) may have a significant effect on the insulation performance of power apparatus. Therefore, identification of PD sources is of interest to both power equipment manufacturers and utilities. With the development of PD measurement techniques, data analysis, signal processing and pattern recognition…
Particle motion of a Lennard-Jones supercooled liquid near the glass transition is studied by molecular dynamics simulations. We analyze the wave vector dependence of relaxation times in the incoherent self-scattering function and show that at least three different regimes can be identified and its scaling properties…
PbS microcrystals with a magic-square-shaped structure were successfully fabricated via a simple hydrothermal route, employing (CH3COO)2Pb and Na2S2O3 as the lead and sulfur source without the assistance of any surfactant or template. S2O32- ions acted not only a supplier of S2- ions but also a coordinating reagent. T…
Different diagnostic techniques are currently available for on-line insulation condition assessment of power transformers. Amongst these techniques a relatively new technique for detecting partial discharges (PD) in the ultra high frequency range of the spectrum is also introduced. The UHF technique has been recently…
Abstract A simple method based on a plasma oscillations theory of solids is proposed for the calculation of mechanical and optical properties such as microhardness ( H ), bulk modulus ( B ), dielectric constant ( ϵ ), polarizability ( α ), electronic susceptibility ( χ ) of A II B IV C 2 V and A I B III C 2 VI semicon…
Electrical degradation of the insulating systems of energy cables is close related to the water treeing and space charge development. In this paper the results of the calculations of the electric field repartition in the insulation of a medium voltage cable affected by water trees and their related space charge are pr…
Nano-silica and micro-silica particles were mixed with silicone rubber. The resulting materials were compared with respect to erosion damage in inclined plane, and surface roughness and contact angle of virgin samples. Results have shown that nano-silica filled room temperature vulcanized (RTV) silicone rubber (SR) ha…
We have calculated the phonons and elastic constants of zirconium in the hexagonal-close-packed (hcp) crystal structure using the Naval Research Laboratory (NRL) empirical tight-binding (TB) approach; the tight-binding parameters are obtained by fitting to ab initio density-functional theory--generalized gradient appr…
Atomic structure and structural stability of neutral oxygen vacancies on amorphous silica are investigated using combined Monte Carlo and density functional calculations. We find that, unlike their bulk counterparts, the Si-Si dimer configuration of surface oxygen vacancies is likely to be unstable due to the high ten…
Nucleation parameters such as metastable zone width, induction period and interfacial energy have been determined for the aqueous solution growth of bis thiourea cadmium acetate (BTCA) single crystals. Solubility of BTCA has been determined for various temperatures. Metastable zone width and induction period values ha…