Materials Literature
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Stress grading of the flashover distance of hollow insulators and composite tension insulators is necessary to improve the electrical and environmental performance and to reduce material needed. Hollow composite insulators are generally designed in such a way that the outer stress is below the breakdown stress of air.…
For high-speed digital circuits a novel elevated-CPW (ECPW) structure with low loss and low dispersion is proposed and the performances are compared with the theoretical prediction. The ECPW is designed with the aid of time domain fullwave FDTD technique and is fabricated using conventional thick-film MEMS processing.…
This paper presents an investigation on the failure of low voltage power capacitors used in the textile industry located in Thailand. The causes of the failure as well as the failure mechanisms of the dielectric used as the insulation of such capacitors are analyzed. It is found that the harmonic resonance can increas…
Space charge can be measured non-destructively as a standard practice now. It has been long suspected that space charge might be critically involved in local dielectric breakdown or tree initiation. It is widely accepted that space charge is formed under dc stress in dielectrics. The author demonstrated a hypothetical…
Surface discharges in a composite dielectric of XLPE power cable joints are one of the main causes of joint failures. This paper discusses the mechanism of surface discharges in a composite dielectric, the effect of interfaces and the practical methods of preventing moisture ingress into joints and cables.
A unit-cell parameter anomaly observed during the precipitation and growth of Ti 3 SiC 2 from a Si-substituted TiC phase is interpreted as the release of latent heat. The observations are used to propose a powder diffraction method for conducting differential thermal analysis as part of in situ phase transition studie…
Of a group of eight 3-phase core form HVDC converter transformers, six have now failed in service. The final failure mechanism has consisted of a turn-to-turn fault, usually in the valve winding. All the windings were produced using continuously transposed conductors. Thermal aging of the insulating materials was evid…
The electric field and potential distributions in the vicinity of non-ceramic insulators under dry and clean conditions are presented. A three-dimensional electric field analysis program, COULOMB, has been used for the calculations. A three-phase 765 kV power line tower geometry is considered for the potential distrib…
The largest loss in an example litz-wire flyback transformer is found during current commutation between windings. In order to reduce this loss, a new optimization method is introduced. The new method optimizes strand size and number in litz wire considering cost and loss. Unlike previous methods, it is valid with two…
This paper reports a low-cost, 256-pixel uncooled infrared microbolometer focal plane array (FPA) implemented using a 0.8 /spl mu/m CMOS process where the n-well layer is used as the active microbolometer material. The suspended n-well structure is obtained by simple front-end bulk etching of the fabricated CMOS dies,…
Permanent magnets are used in a wide variety of applications: sensors, motors, actuators, alternators, hard drives, and speakers. While ceramic magnets (hard ferrite) were the material of choice for the last three decades, neodymium iron boron magnets, bonded and sintered, have surpassed ceramic magnets as the benchma…
Hydrocarbon emissions of a vehicle during cold start must be reduced to meet stringent emission regulations. In this paper, three honeycomb hydrocarbon adsorbers were prepared by using H−ZSM-5 and materials of conventional three-way catalysts. A new method was proposed, namely, temperature-programmed adsorption, to ev…
The growth of electrical trees in heterogeneous solid dielectrics was investigated by means of two-dimensional numerical simulations. In contrast to conventional approaches the introduced newly developed algorithm is based on a deterministic model together with a spatial distribution of the electrical breakdown streng…
Knowledge on how wave propagation characteristics and other parameters depend upon cable design is an important base in establishing diagnostic methods for cable insulation. In this study, a shielded medium voltage XLPE cable is investigated and a high frequency based measurement technique is used to measure the prope…
Crystallizing protein–protein complexes remains a rate-limiting step in their structure characterization. Crystallization conditions for the known protein–protein complexes have been surveyed in both the Protein Data Bank and the BMCD database. Compared with non-complexed proteins, crystallization conditions for prote…
In previous work, the authors proposed a low (6) dimensional model for a thin magnetostrictive actuator that was suitable for real-time control. One of the main results of this modeling effort was the separation of the rate-independent hysteretic effects from the rate-dependent linear effects. The hysteresis phenomeno…
A Monte Carlo method is used to simulate the competition between the molecular relaxation and crystallization times in the formation of a glass. The results show that nucleation is avoided during supercooling and produces self-organization in the sense of the rigidity theory, where the numbers of geometrical constrain…
Multi-walled carbon nanotubes (MWNTs) are manipulated in 3D space with a 10-DOF nanorobotic manipulator, which is actuated with PZTs and Picomotors/sup TM/ (New Focus Inc.) and operated inside a scanning electronic microscope (SEM). The coarse linear resolutions of the manipulator are better than 30 nm (X, Y, Z stages…
This article reports electrostatic transportation of water droplets on superhydrophobic alkylketene dimer (AKD) and Teflon AF/sup R/ surfaces. The actuation is based on electrostatic forces generated by metal electrodes placed underneath the surface. By switching the electrode voltages, the droplets moved stepwise alo…
Crowded solutions of multiarm star polymers, representing model colloidal spheres with ultrasoft repulsive interactions, undergo a reversible gelation transition upon heating in solvents of intermediate quality (between good and Theta). This unusual phenomenon is due to the kinetic arrest of the swollen interpenetrati…