Materials Literature
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Results of measurements and analyses of leakage current (LC) patterns on field-aged and non-aged insulators are presented. The field-aged insulators were exposed to marine and industrial pollutions as well as to tropical weather conditions for one year. The LC measurements were performed on them under natural and arti…
Since 1960, polymer insulator has been employed as an outdoor insulator for high voltage ascribed to its excellent aging characteristics compared to those of ceramic insulator. However, in spite of various investigations related to the polymer insulator, its aging mechanism due to acid rain have not been well elucidat…
This paper describes the influence of high voltage harmonics on partial discharge (PD) phase resolved images. The evolutions of these images as a dependency of total harmonic distortion (THD) parameter as an assessment factor, calculated by means of Fast Fourier Transform (FFT) are shown.
Following an initial elastic strain, a crystal responds to an increasing external stress by either breaking up into pieces, or else plastically changing its shape before failure. In this paper, the different behaviours of a crystal—brittle cleavage versus ductile deformation—are briefly discussed, and the transition f…
A description is given of a straightforward physical model, which is based on only a few physically meaningful parameters and that allows to describe the PD behaviour resulting from specific insulation defects. It is demonstrated that computer simulations of PD pulse sequences on the basis of this model correspond clo…
The determination of the thermal conductivity of thin films is of great interest both for understanding the structure and conduction mechanism and for numerous technical applications of these films. The thermal conductivity /spl lambda/ is a crucial term of the thermoelectric figure of merit z=/spl alpha//sup 2//spl s…
Electrical rotating machines are subjected to nonsinusoidal wave shapes when supplied from high frequency inverters. PWM (pulse width modulated) voltage sources with steep wave fronts can be destructive to the insulation and criteria normally used under sinusoidal conditions cannot necessarily be transposed to this ne…
There are many applications where thermoelectric (TE) coolers can be used effectively as power generators. In fact, where temperatures are less than 500 K, TE cooling modules are the best choice for power generation, whether it be from a cost or performance standpoint. The literature available on this subject is scarc…
A series of molecules having a hydroxyl group attached to the end of one terminal chain were found to form a sequence of smectic antiphases, SmÃ, Sm, Sm and Cr, with a growing degree of in-plane molecular ordering. The bilayer structure of the modulated phases is due to the formation, through hydrogen bonding, of mole…
Ferrite cores of magnetic components used in power electronics are often biased with a DC or low frequency premagnetization. Work has shown that a bias field may have significant influence on the remagnetization losses and therefore has to be considered in the component design. Using a precise measurement setup this p…
Density-functional based calculations are used to investigate low energy core structures of 90 ° partial dislocations in diamond and 3C-SiC. In both materials dislocation glide is analysed in terms of kink formation and migration and the fundamental steps to kink migration are investigated. We find the C terminated co…
Abstract Polymer alloys have been used as an alternative to obtain polymeric materials with unique physical properties. Generally, the polymer mixture is incompatible, which makes it necessary to use a compatibilizer to improve the interfacial adhesion. Nylon 6 (PA6) is an attractive polymer to use in engineering appl…
In this paper, the authors propose a calculation method for the compensating current reference of an active power filter, where a nonlinear load exists in a three-phase three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq m…
A transition-metal oxide NaCo/sub 2/O/sub 4/ system has been synthesized by a standard solid-state reaction method, and the thermoelectric properties have been measured. The resistivity /spl rho/ and the thermoelectric power /spl alpha/ of the as-sintered NaCo/sub 2/O/sub 4/ is 2 m/spl Omega/cm and 100 /spl mu/V/K at…
Partial discharges are a symptom of most of the stator winding insulation deterioration mechanisms found in motors and generators rated 6 kV or more. Thus, partial discharge testing has been used for over 40 years as a means of determining the maintenance requirements of such high voltage stators. As the benefits of s…
In flip-chip packaging, an underfill mixture is placed into the chip-to-substrate stand-off created by the array of solder bumps, using a capillary flow process. The underfill mixture is densely filled with solid silica particles to achieve the desired effective coefficient of thermal expansion. Thus, during the flow…
One-pot reaction between the dinuclear [MnII2(bpym)(H2O)8]4+ complex and the mononuclear [MIV(CN)8]4− unit (M = Mo and W; bpym = 2,2′-bipyrimidine) in aqueous solution yields the novel heterobimetallic complexes of formula {(μ-bpym)[Mn(H2O)]2-(μ-NC)6M(CN)2} with M = Mo (1) and W (2). 1 and 2 are isostructural three-di…
This paper provides analytical and graphical tools for the study, performance evaluation and design of the popular carrier based PWM methods which are widely employed in PWM VSI-fed AC motor drives. Simple techniques for generating the modulation waves of the high performance PWM methods are described. The two most im…
We present adsorption isotherm results for Ne, CH4, and Xe on bundles of close-ended single-wall carbon nanotubes, for coverages above the completion of the first layer. We find a small, sharp, substep present in the second-layer data for Ne and CH4, and a weaker feature, that produces an isothermal compressibility pe…
The purpose of this study is to gain insight into the instability which is observed, under operative conditions, in SnO 2 nanocrystalline materials. To this end, the binding and fragmentation energies of SnO 2 crystalline grains have been evaluated quantum mechanically at the semi-empirical level using the extended De…