Materials Literature
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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…
Research on the use of shape memory alloy actuators for miniature applications is interesting due to their high power-to-weight ratio and self-sensing capabilities based on resistance-strain models. Hysteresis behaviour in addition to slow cooling response makes the control a major problem to be addressed. This work i…
This paper demonstrates the effects of a laminated busbar on power electronics circuits, and compares its characteristics to those of other power distribution topologies. Included in the discussion are physical as well as electrical characteristics, along with the manufacturing implications that need to be considered.
A simulator is developed to model and design high strain shape memory alloy (SMA) tension actuators. The simulator may be used predict characteristics of a given actuator, or to design its geometry under specifications such as force, speed, stroke and size. The accuracy of the model is verified experimentally in refer…
Previous work by the authors has involved producing a non-linear conductivity characteristic in a thermoset polymer (polyester) by the introduction of particulate ZnO. This work has now been extended to cover a thermoplastic material (LDPE). Filler/resin ratios have been varied to obtain a critical level at which the…
Surface (air−fluid) and interfacial (fluid−fluid) tensions of coexisting isotropic and anisotropic aqueous suspensions of microcrystalline cellulose have been investigated as a function of suspension concentration and ionic strength using the pendant drop method. The surface tension of the individual phases remained c…
A geometrical model of a porous silicon structure is proposed. The resulting size distribution spectra are analyzed by their relation to photoluminescence and Raman scattering. Both experimental data are investigated and compared to those results. The model well describes the presence of a low-energy part of the photo…