Materials Literature
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Characterization of ferroelectric ceramics using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy, Jae-Nam Kim, Kwang-Soo Shin, Byung-Ok Park, Jin-Hong Lee, Nam-Kyoung Kim, Sang-Hee Cho
The torque is measured in a contactless technique without special treatment of the shaft, using the magneto-elastic effect of ferromagnetic materials. Strain or stress due to moments lead to a change of magnetic properties of the material (hysteresis deformation, permeability changes). Magnetoelastic sensors are disti…
Ternary tungsten carbo nitride WCN films and titanium nitride TiN films were deposited with atomic layer deposition as diffusion barrier materials for copper metallisation. The growth behaviour on different substrates and surface closure was studied by Rutherford backscattering spectroscopy (RBS). It was demonstrated…
Discharge signatures have been studied in a combined transformer oil/impregnated paper insulation system subjected to AC high voltage. A semi-homogeneous sphere-plane electrode configuration was used to simulate wedge discharges in a power transformer. The moisture level of the impregnated paper was varied between 0.3…
Presents a model providing time-dependent solutions for charge densities, field and electroluminescence in dielectric films under uniform dc field. The model encompasses bipolar carrier production, trapping and recombination phenomena. Numerical simulation is applied to transport in low density polyethylene (LDPE).
For buried gas insulated transmission lines (GILs), a coating against corrosion is absolutely necessary and similar to most other directly buried metallic installations. Active corrosion protection, also called catholic protection, may be added to take care about possible failures of the coating as an additional quali…
The development of time-frequency and time-scale transforms has progressed quickly for 20 years. This development and the progression of the numerical acquisition enable the utilization of these mathematical tools to analyze partial discharges (PD) in the induction motors insulation. Some papers have been written abou…
The adoption, in electrical drives, of power supplies equipped with fast electronic devices lead to new "life" problems (e.g. degradation due to partial discharges) which impact on the design of the relevant electric machines insulation systems. Hereby are reported some results of an investigation about the behaviour…
Switched polarization fatigue was investigated for CVD PZT ferroelectric films of thickness <100 nm. The data shows that negligible switched polarization degradation occurs during an initial incubation period, CTF*, which can last up to /spl sim/10/sup 8/ polarization reversal cycles. This incubation period was found…
Partial discharge (PD) is identified as a main factor contributing to the insulation deterioration in HV equipment including underground cable. This is the first time an attempt has been made to investigate the effect of soil thermal resistivity on PD activities in underground power cables. In this paper, a detailed e…
This work presents a new modeling strategy to account for the energy stored in the volume around the air gap in gapped magnetic components. The approach is based on the Schwarz-Christoffel transformation, which has been extended to axisymmetrical magnetic components. The results have been validated by means of compari…
The surface charge decay and space charge distribution in corona-charged low-density polyethylene (LDPE) were investigated. The space charge distribution was measured at 30/spl deg/C with the pulsed electro-acoustic (PEA) method, where a corona charged specimen was set between a semiconductive electrode and an Al elec…
Partial discharge(PD) tests were used to evaluate the insulation condition of seven large motors. These tests were conducted using a conventional partial discharge detector (PDD), turbine generator analyzer (TGA) and partial discharge analyzer (PDA). Off-line PD measurements were performed using the PDD. Offline PD pu…
Hydrophobicity of polymeric insulating material surface such as silicone rubber insulator was studied by using image data analysis of the sample surface. Hydrophobicity of polymer was evaluated by the motion of water droplets on the sample surface under AC high field application. The vibration image of the water dropl…
The electric field and voltage distributions along wet polymer insulators are calculated using COULOMB, a three-dimensional electric field analysis software package. These distributions are distorted by the presence of water droplets on the surface of the insulators. The cases analyzed are based on several stages of t…
There are various methods for determining the reaction parameters using thermal analysis data. In recent years, genetic algorithms have been considered as a new method for the determination of kinetic parameters. In the present study, calcination kinetics of ulexite was investigated by thermogravimetry (TG) using the…
Scattering losses for fused silica were measured over a wide wavelength range (193-800 nm) using different laser sources. The data indicate that scattering centers are smaller than ~ 12 nm, and scattering is consistent with Rayleigh type even at 193 nm. Scattering losses scale with wavelength as 1/λ<sup>4</sup>,…
Experimental investigation into the behaviour of partial discharges (PD) in different types of defect models are described in this paper. The models were used to study the waveshape and frequency spectra of the signals resulting from discharges. This information is then used to investigate the effect on the signals of…
Gaseous voids in polymeric dielectric materials are likely locations for partial discharges (PD). Numerous parameters influence the development of the charge avalanche. To date, various experiments and simulations have been carried out to investigate the PD behaviour as a function of the geometry of disc-shaped or sph…
The performance and reliability of electronic devices composed of multiple thin layers of material are highly dependent on effective thermal management. Since the thermal properties of thin films, such as SiO/sub 2/, can vary considerably from bulk values, the determination of those properties is critical for the purp…