Materials Literature
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Carbon nanotubes possess a very rich spectrum of plasmon modes. For the single wall, metallic carbon nanotubes, in addition to the high frequency plasma modes in the UV range and the depolarization shifted van Hove plasma resonances, there are also low frequency, gapless plasmon modes in the far-infrared frequency ran…
High performance antennas have been realized on proton-implanted Si with 10/sup 6/ /spl Omega/-cm resistivity. Sharp antenna resonance and low loss up to 20 GHz are observed indicating excellent antenna quality. In contrast, very poor antenna characteristics are found on conventional oxide-isolated Si because of the l…
Electromagnetic wave scattering by two rectangular troughs on a conducting ground plane, which is the simplest trough-grating geometry, is rigorously analyzed using the Kobayashi potential method. The formulation is extended and derived here for the H polarization case. By using the derived far field solution, numeric…
In this paper, the characteristics of corona current of a single insulator under high voltage is studied in different methods. The results show that the characteristics of corona current are different with their status. From these characteristics, an insulator's status can be decided online.
The aim of this work is to propose a mathematical model for the iron losses prediction in soft magnetic materials with any supply voltage. The starting point for the analysis is the knowledge of the iron losses with sinusoidal supply. The model is based on the separation of the losses contributions due to hysteresis,…
Cable joints are generally known to be the weak points of underground distribution lines. One of the most common failure modes of premolded cable joints is linked to the occurrence of dielectric breakdown at the interface. Many parameters may influence the dielectric strength of a cable-joint interface: surface roughn…
The electrical power industry worldwide has some 35 years of manufacturing and field experience with compressed gas, SF/sub 6/ or SF/sub 6//N/sub 2/ mixtures, switchgear and transmission lines (GIS/GIL). Such equipment is in use for distribution as well as the highest transmission voltages, and a 1000 kV GIS is curren…
For dimensioning and optimum control of Peltier coolers and heat pumps, an accurate numerical description of the performance parameters under various operation conditions is required. Here, the situation for homogeneous bismuth antimony telluride based Peltier cooler material is discussed, using representative values…
Non-linear field-grading materials are used to avoid stress concentrations in many AC and DC high voltage applications. One way to obtain materials having the desired non-linear characteristics is to use compounds, such as an insulating polymer with a semiconducting filler. A possible filler is silicon carbide (SiC).…
This paper presents a new approach of modeling the dynamic behavior of supercapacitors using impedance spectroscopy. The new Matlab/Simulink model can be used in simulating the voltage response and energy efficiency, e.g. for automotive power systems. The model in the frequency domain, the parameter calculation as wel…
Highly efficient, segmented thermoelectric unicouples incorporating advanced thermoelectric materials with superior thermoelectric figures of merit are currently being developed at the Jet Propulsion Laboratory (JPL). These segmented unicouples include a combination of state-of-the-art thermoelectric materials based o…
Samples of ${\mathrm{La}}_{0.6}{\mathrm{Sr}}_{0.4}{\mathrm{FeO}}_{3\ensuremath{-}\ensuremath{\delta}}$ compounds prepared by quenching in different gaseous environments were studied by x-ray diffraction, neutron diffraction, magnetization measurements, and M\"ossbauer spectroscopy (MS). All materials are single phase…
gamma-alumina is known to transform to theta-alumina and finally to alpha-alumina upon thermal treatment with a catastrophic loss of porosity and catalytic activity. First-principles calculations were performed to investigate the atomic scale mechanism of the gamma- to theta-alumina transformation. The transformation…
We present a self-consistent field theory (SCFT) for dilute solutions of semiflexible (wormlike) diblock copolymers, each consisting of a rigid and a flexible part. The segments of the polymers are otherwise identical, in particular with regard to their interactions, which are taken to be of an Onsager excluded-volume…
This paper summarizes our efforts to develop fast algorithms for density functional theory (DFT) calculations of inhomogeneous fluids. Our goal is to apply DFTs to a variety of problems in nanotechnology and biology. To this end we have developed DFT codes to treat both atomic fluid models and polymeric fluids. We hav…
An improved thermoelectric generator (TEG) for the heavy duty class eight diesel trucks is under development at Hi-Z Technology. The current TEG is equipped with the improved HZ-14 thermoelectric module, which features better mechanical properties as well as higher electric power output. Also, the modules are held in…
Iron perovskites ${\mathrm{CaFeO}}_{3}$ and ${\mathrm{La}}_{0.33}{\mathrm{Sr}}_{0.67}{\mathrm{FeO}}_{3}$ show charge disproportionation, resulting in charge-ordered states with ${\mathrm{Fe}}^{3+}:{\mathrm{Fe}}^{5+}=1:1$ and $=2:1,$ respectively. We have made photoemission and unrestricted Hartree-Fock band-structure…
To meet the increasing world demand for energy, the rate of depletion of non-renewable energy sources must be reduced while developing alternative renewable sources. This can be achieved by increasing the overall thermal efficiency of conventional power plants. One way to do this is by waste heat recovery. Most of the…
A series of CuCoZnAl-multicomponent mixed oxide catalysts with various Cu/Co atomic ratios were prepared by the thermal decomposition of CuCoZnAl-hydrotalcite (HT)-like precursors at 450 °C in static air atmosphere. The XRD of calcined materials revealed the formation of a mixture of CuO and ZnO, Co 3 O 4, and/or ZnCo…
The speed control of ac-electric motors can be carried out efficiently by adjustable speed drives (ASD), which are constituted by an AC/DC conversion block, a DC filter and a DC/AC inverter representing the core of the whole power converter. A new generation of DC/AC converters for adjustable speed drives, the so-call…