Materials Literature
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The thermodynamic properties and the morphology of syndiotactic polystyrene solid samples exposed to solvents (benzene and toluene) are investigated. It is shown that, as far as the melting properties are concerned, there is no significant difference between these samples and solution-cast samples. This suggests that…
The photoluminescence efficiency of InP nanocrystals prepared via the dehalosilylation reaction between indium chloride and tris-(trimethylsilyl)phosphine in mixtures of trioctylphosphine and trioctylphosphine oxide can be drastically improved by etching with fluorine compounds, as proposed several years ago by Micic…
We present density-functional theory for linear and nonlinear response functions using an explicit exponential parametrization of the density operator. The response functions are derived using two alternative variation principles, namely, the Ehrenfest principle and the quasienergy principle, giving different but nume…
We investigate the optical properties of spherical gold and silver clusters with diameters of 20 nm and larger. The light scattering spectra of individual clusters are measured using dark-field microscopy, thus avoiding inhomogeneous broadening effects. The dipolar plasmon resonances of the clusters are found to have…
X-ray photoelectron spectroscopy (XPS) investigations of supported nanoparticles smaller than 10 nm show a significant shift of the electron binding energy of core levels compared with the bulk values. In this work, such shifts were examined at differently supported and prepared gold nanoparticles for the 4f electron…
A major challenge to increasing bandwidth in optical telecommunications is to encode electronic signals onto a lightwave carrier by modulating the light up to very fast rates. Polymer electro-optic materials have the necessary properties to function in photonic devices beyond the 40-GHz bandwidth currently available.…
We report on the high-temperature ferromagnetism in Co-doped ZnO films fabricated by the sol–gel method above 350 K. The lattice constant of c axis of wurtzite Zn1−xCoxO follows Vergard’s law for 0<x<0.25. For Zn1−xCoxO with x⩾0.25, a secondary phase is detected. The Zn1−xCoxO exhibits ferromagnetic beha…
Despite being first demonstrated over 160 years ago, and offering significant environmental benefits and high electrical efficiency, it is only in the last two decades that fuel cells have offered a realistic prospect of being commercially viable. The solid oxide fuel cell (SOFC) offers great promise and is presently…
The scope of this paper is to present some aspects in modeling of electrical field in high-voltage direct-current (HVDC) cables. Some computation models for electrical fields are presented. Computation procedures are developed for DC cables with one and two imperfect dielectric insulation layers for capacitive and res…
While measuring the resistive losses in transformer windings, a great difference between the measurement results of additional losses was noticed due to the skin-effect at the transformer without box and the theoretical calculated results. In order to find the reason for the phenomenon, measurements of resistive losse…
AC dissipation current waveforms of polyethylene and polypropylene films show nonlinear distortion in AC high-field region. This non-linearity was supposed to be related to the behavior of AC space charge formation in the sample. However, the measurement of AC space charge distribution is not so easy due to the resolu…
For the polymeric insulating materials such as polypropylene (PP) and low density polyethylene (LDPE), the surface oxidization and chain scission that deteriorate the insulation performance are induced by the irradiation of the ultraviolet photons. Photochemical reactions are responsible for such oxidization and bond…
In this paper, we have investigated the trapping parameters in the surface layer of two kinds of insulating materials. The final aim is to construct the relationship between the surface microstructure of an insulating material and its flashover phenomena.
PD test data on various generators and motors has been collected over 15 years using on-line partial discharge analyzers. A large PD test database has been established. The database provides an overall view of PD activity on rotating machines. Statistical analysis of the database provides a study of PD distribution wi…
New methods of switched power supplies and power supply system design for microprocessor devices, based on the use of modern high-frequency amorphous alloys with a rectangular hysteresis loop, are proposed. The basic technical solutions are described and the results of research are shown. The main technical data of mu…
This paper compares insertion loss and T-resonator methods to characterize the electrical properties of oxidized porous silicon. The insertion method provided consistent dielectric and attenuation data on a range of conductive substrates, while the T-method was limited to low loss substrates. The estimated effective d…
This paper proposes a method for determining maturity levels of durian by using nondestructive vibration. The vibration is transferred directly through durian at a region between prickles located at the middle of durian. The measurement of frequency response from vibration of durian is performed by using laser Doppler…
The scale down models of pre-compressed mineral oil insulation system have been studied under surface flashover of the surface of insulation. The experimental investigations have been dealt with for conventional AC, DC and superimposed voltages of AC/DC at different electrode gap distances. Two types of models using c…
Performance of thermoelectric materials and devices depends upon various features on different levels from microscopic to macroscopic scales. On the atomic scale, to find new multi-component compounds with complex electronic and crystal structures is a way to high-Z thermoelectric materials. On the nano-scale, quantum…
The failure probability of the insulation in HV components can be studied through partial discharge (PD) measurements to detect defects. A numerical model, previously developed by the authors for the simulation of PD activity in a spherical void embedded in epoxy resin, is implemented for a flat cavity under a diverge…