Materials Literature
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Through an interplay between scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we show that bridging oxygen vacancies are the active nucleation sites for Au clusters on the rutile TiO2(110) surface. We find that a direct correlation exists between a decrease in density of vacancies…
Thermal fatigue tests were performed on tungsten-copper brazed specimens within the designed temperature range of design temperature of the Fusion Experimental Reactor (FER) divertor collector plates. Two types of brazing fill metals (nickel-based and titanium content silver-based metals) were selected for bonding the…
Abstract Switching to N 2 or CO 2 for foaming thermoplastics increases cooling requirements for a foam extrusion line. Factors affecting cooling heat transfer and proposed correlations are described. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 69–74, 2003; Published online in Wiley InterScience (www.interscienc…
Charge buildup in 30- mu m-thick films of polypropylene irradiated with monoenergetic electron beams of 10-45-keV energy is investigated. Using the split-Faraday cup, the mean charge depths at the beginning of electron injection, at the termination of injection, and 10 minutes after injection are measured. It is found…
Electrical conduction in the aromatic polyamides commercially known as Nomex or HT-1 film is studied over a temperature range of 50-200 degrees C and electric-field strengths up to 400 kV-cm/sup -1/ over a time range of 1-60 min. This material has excellent thermal and mechanical properties, making it suitable for hig…
The authors reevaluate the required test voltage, necessary stabilization time, and traditional measurement frequencies for corona probe testing. Studies indicate that the corona inception voltage (CIV) can be estimated for each stator slot. When a coil is operated below its CIV, deterioration due to electrical discha…
A Be-packed bed between the high-temperature breeder and low-temperature coolant has been proposed for an ITER solid breeder base blanket. The design offers the possibility of adjusting the solid breeder temperature through active control of the packed-bed effective conductivity; such control can potentially be achiev…
Four candidate materials were evaluated for use as high-temperature capacitor dielectrics. The materials investigated were polybenzimidazole polymer and three aramid papers. The samples were characterized with and without heat treatment in terms of their dielectric constant and loss. These properties of the heat-treat…
A light and high-torque servo motor using SMA (shape memory alloy) is presented. Its design method is derived using the dynamical properties of SMA and the geometrical relationships of the SMA motor. A fixed-ring-type SMA motor with a synchronous belt was designed, and its torque and maximum rotary speed were calculat…
One single-layer and two four-layer example winding structures are used to illustrate the impact of excitation frequency on the magnetic field intensity and current density distributions in transformer windings. By plotting the distributions as phasors in three-dimensional isometric plots, greater insight is gained in…
Inelastic x-ray scattering data of liquid Li, Na, and Al for dynamical structure factors have been analyzed by proposing a semiempirical model. The model is based on the extension of the hydrodynamic model to the viscoelastic region so that it satisfies the first four nonvanishing sum rules. It has been found that the…
A millimeter-size actuator to drive a rotary joint for a small robot was designed and fabricated using shape memory alloy (SMA), which has the merits of large force/weight and extendability to micron size. The actuator is of the push-pull type, composed of two SMA sheets of 0.05 mm*0.5 mm*3 mm. The theoretical model o…
Net plant efficiencies of fuel cell power plants, operated with natural gas fuel, are analyzed on the basis of expected fuel cell performance. A comparison of net plant efficiencies of three types of fuel cell power generation systems is discussed. They are a phosphoric acid fuel cell (PAFC) system, a molten carbonate…
The controversial origins of the unusual dynamics of miscible polymer blends are incisively probed through computer simulations. The distribution of mobilities experienced by a probe monomer in a miscible blend of chains with disparate glass transition temperatures is found to be much broader than in the pure polymers…
Two simple control strategies for current-controlled VSI-PWM (voltage-source-inverter-pulse-width-modulated) transistor inverters are presented. Both methods are based on three-level hysteresis comparators that select appropriate inverter output voltage vectors using a switching EPROM table. The first controller works…
We report on the electron paramagnetic resonance (EPR) and optical absorption and fluorescence spectroscopy of YAl 3 (BO 3 ) 4 single crystals doped with 0.2 mol% of trivalent chromium. From EPR we determine that the Cr 3+ ions reside in sites of essentially octahedral symmetry with an orthorhombic distortion. The gro…
In this review of capacitor fundamentals, the author attempts to clarify the modes of operation of the broad spectrum of capacitors, including paper/polymeric films, electrolytics, and ceramics. How each class of capacitor performs in both low- and high-power electronics is discussed in detail, with emphasis upon deli…
The surface morphology of Bence-Jones protein (BJP) crystals was investigated during growth and dissolution by using in situ atomic force microscopy (AFM). It was shown that over a wide supersaturation range, impurities adsorb on the crystalline surface and ultimately form an impurity adsorption layer that prevents fu…
The authors report on progress in the development of millimeter-wave junction circulators for the band near 31 GHz, incorporating the technique of exploiting the high effective internal magnetic anisotropy field of barium and strontium magnetoplumbites (hexagonal ferrites) to eliminate the external permanent magnet re…
The authors present a model of electrical aging of extruded cables based on actual data and realistic experimental conditions. It is shown that a simple model partially based on the rate theory associated with the name of Eyring describes very well the aging of polyethylene (PE), crosslinked PE, and ethylene-propylene…