Materials Literature
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Epoxy resin is widely used as an insulation material in many electrical apparatuses because of its excellent electrical and manufactural characteristics. It is usually mixed with filler to improve mechanical and thermal characteristics. In order to quantitatively clarify the effect of fillers on the treeing phenomenon…
The purpose of the work presented here is to characterise polymeric HVDC cable insulation consisting of lapped thin film polypropylene with respect to DC current conduction and partial discharge activity in air filled butt gaps. The PD activity was found to strongly increase with increasing temperature and applied ele…
Abstract 3‐Chlorothiophene (CT) was electrochemically polymerized in mixed electrolytes of a boron trifluoride diethyl etherate solution containing 0–20% (by volume) sulfuric acid. The oxidation potentials of the monomer in these media were measured to be only 1.06–1.31 V (vs Ag/AgCl). These values were much lower tha…
We present a theoretical study of bond-length and angle variations in relaxed, epitaxially strained, and amorphous ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ alloys. Our approach is based on Monte Carlo simulations, within the semigrand-canonical ensemble utilizing Ising-like identity flips, and in conjuction…
The PEA (pulsed electro-acoustic) and PWP (pressure wave propagation) methods are widely used effective techniques for measurement of space charge distribution in dielectric materials. Since these techniques are using pressure waves as a detecting signal, however, it is inevitable to be affected by an attenuation effe…
We study the coarsening dynamics of two- and three-dimensional biaxial nematic liquid crystals, using Langevin dynamics. Unlike previous work, we use a model with no a priori relationship among the three elastic constants associated with director deformations. Biaxial nematics possess four topologically distinct class…
The paper presents a method to determine the effects due to the punching process on soft magnetic materials used in the electrical machines. The proposed methodology, is based on a full experimental approach. Four wound cores, having the same geometrical dimensions, have been assembled as the overlap of a different nu…
The technique of crystal truncation rod (CTR) diffraction is widely used for studying the structure of crystalline surfaces and interfaces. The theory and experimental details of the technique are well established; however, published methods for structure-factor calculations are typically based on a simple surface cel…
Underground cable accessories used in medium voltage cable systems need a highly reliable stress control system in order to maintain and control the insulation level which is designed for estimated life times longer than 30 years of service. The term "electrical stress control" refers to the cable termination function…
The electric field in a dielectric changes from capacitive grading immediately after the voltage application to, resistive grading under steady state conditions. In the case of a polymeric dielectric, the conductivity is known to be strongly dependent on both the electric field and the temperature, characterized by an…
On site partial discharge (PD) methods have become successful tools to diagnose and monitor cable circuits. This paper describes the background of these methods, some fundamentals and challenges. The first section gives a brief introduction to and definition of the 0.1 Hz or very low frequency (VLF) PD methods. The ne…
We consider a model mixture of hard colloidal spheres and nonadsorbing polymer chains in a theta solvent. The polymer component is modelled as a polydisperse mixture of effective spheres, mutually noninteracting but excluded from the colloids, with radii that are free to adjust to allow for colloid-induced compression…
We report here a detailed study of sacrificial layer dissolution of photoresist by acetone in microchannels. The effects of channel geometry as well as photoresist characteristics such as thermal cycles and UV exposure are considered and tested. Test channels were designed and fabricated ranging in height from 2 /spl…
The spin population distribution in the ferromagnetically coupled hetero-bimetallic chain compound [MnNi(NO(2))(4)(en)(2)] (en = 1,2-ethanediamine) has been investigated by means of polarized neutron diffraction experiments, and the results compared with those from theoretical estimates obtained via calculations based…
The use of parallel windings is a very common practice in planar magnetics, where the copper thickness is usually very low to handle typical current values. Besides, the use of parallel turns allows applying better interleaving among the different windings. This work presents a review of the proper modeling strategy i…
A variational solution of the coupled electron-phonon Boltzmann equations is used to calculate the phonon drag contribution to the thermopower in a one-dimensional system. A simple formula is derived for the temperature dependence of the phonon drag in metallic single-walled carbon nanotubes. Scattering between differ…
Utilizing refrigeration may provide the only means by which future high-performance electronic chips can be maintained below predicted maximum temperature limits. Widespread application of refrigeration in electronic packaging will remain limited until the refrigerators can be made sufficiently small so that they can…
Isotropic liquid droplets are formed by different mechanisms near the smectic−isotropic phase transition in smectic freely suspended films. Because of the layered structure of the smectic films, the interplay of tensions that determines the droplet geometry is essentially different from that of liquid droplets on soli…
Abstract Novel epoxy‐terminated monomers based on imine groups were synthesized and their mesogenic properties studied. Aliphatic spacers of different lengths were introduced between the rigid unit and the glycidylic group, and their liquid‐crystalline behavior was examined. They were reacted with primary aromatic dia…
The high-frequency dynamics of ${\mathrm{Sr}}_{0.61}{\mathrm{Ba}}_{0.39}{\mathrm{Nb}}_{2}{\mathrm{O}}_{6}$ are studied using the micro-Brillouin scattering technique to elucidate the uniaxial relaxor behavior. It is found that broad central peaks (CP's) appear at about 400 \ifmmode^\circ\else\textdegree\fi{}C, which i…