Materials Literature
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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…
The aging rate of fluid-impregnated Kraft insulation paper varies with the dielectric fluid composition. Reaction rates of thermally upgraded paper aged in natural ester fluid (vegetable oil) are compared to those in conventional mineral oil. Rates are determined using tensile strength and degree of polymerization mea…
This paper discusses secondary unit substations transformers (USTs) ranging from 300 kVA up through 2500 kVA with 34.5 kV maximum primary voltages and with secondary voltages 600 volts and below. The first part of this paper discusses USTs belonging to two general categories, liquid-type and dry-type (nonliquid type).…
This paper presents the design and experimental results of robust control of a rotary servo actuated by an SMA wire. A rotary servo device using NiTi type of SMA wire have been designed and fabricated for this research. This rotary servo is equipped with an RVIT (rotary variable inductance tansformer) sensor for angul…
Metal ion reservoirs in a Ti-AlCu-TiN metal system with W vias have been shown to increase electromigration lifetimes in barrier metal systems. In this study, it is empirically shown that EM lifetime increase is related to the natural-log of reservoir length in a constant width line. In this process, where vias do not…
It seems that the lower figure of merit for sintered n type telluride compounds is due to the selenium segregation at the grain boundaries. We present the transport properties of the Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ binary compounds in terms of stoichiometric deviation. We discuss these properties along the p…
Experiences from field tests of a model-based molten metal analysis estimation system for the LD converter process are reported. Experiments have been carried out during a six-months long period on two converters at SSAB Tunnplat AB in Lulea, Sweden. The results achieved prove the viability of the approach taken and i…
Partial discharge (PD) activity is a localised high frequency stress mechanism which causes degradation of gaseous, liquid and solid electrical insulations. In an SF/sub 6/ gas-insulated system (GIS), partial discharge occurs due to the presence of electrode protrusions, fixed particles on insulating surfaces or movin…
A noninvasive ultra-wide band (UWB) partial discharge technique was employed in cable diagnosis of Mexico City underground distribution feeders. The technique presented here was applied to over 2000 joints, 400 terminals and thousands of meters of installed paper insulated impregnated cables rated at 23 kV. The techni…
Composite insulation materials may have small gaseous voids caused by the manufacture process and/or by mechanical stress. The time delay of partial discharge (PD) inception after voltage application in such small voids depends on various parameters including the gaseous volume, and it is subjected to considerable sca…
This paper shows that the charge detrapping rate follows an Arrhenius-type law when the poling electrical field is large enough to cause copious injection of electrons, so that the transport and trapping process is dominated by electronic carriers. At fields close to the charge accumulation threshold, the tested mater…
The synchronous machine has a relevant importance among the power system components. It is, by nature, an element complex by itself. Therefore, a detailed model of this component is needed to analyze its behaviour under different operation conditions and its influence of the rest of the system. In this state space mod…
There is increasing interest in understanding the characteristics of excess charge in insulating polymeric materials. This interest arises not only from the conviction that such charge is conducive to failure of the insulation but also from the increasing ease and sophistication with which the spatial distribution of…
Bimodal distributions of time-to-failure (TTF) were often seen in copper via electromigration (EM) tests. The failure mechanism of the stressed samples could be correlated to time-to-failure of the EM test. Early-failures were via-related, whereas late-failures were metal-stripe-related. The failure mechanisms are dis…
In this paper, preliminary results of testing generator stator insulation using PD detection at oscillating voltage waves are presented. Based on laboratory investigation, on a full scale stator insulation system, a comparison of PD behavior: the PD inception conditions and PD levels at 50 Hz AC stresses and at oscill…
For many years, PD-analyses have been a widely used tool in the condition monitoring of electric equipment. Over the years, many tools have been developed in the aim to characterise the empirical data. Usually frequency distributions of accumulated data are considered and displayed as purely descriptive /spl phi/qn-pa…
Accelerated electrical breakdown in ERIP (epoxy resin impregnated paper) condenser bushings has been investigated. Inter-foil breakdown of the grading foils, via electrical treeing, occurred over several 10s of hours when the applied electrical stress was /spl sim/6 times the normal working stress. The progress of int…