Materials Literature
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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…
Abstract The thermoanalytical method offers a convenient means for testing a starting material before the end application. Differences in the kinetic parameters between neat and irradiated nylon 66 samples were estimated in the temperature range of 25°C–800°C by thermogravimetric analysis (TGA) and in the range of 25°…
A simple model partially based on the rate theory is proposed to describe the electric aging of polyethylene (PE) and cross-linked PE (XLPE) cable insulation. It is assumed that the stress (electric or mechanical) reduces the height of the energy barrier controlling the process under study. The model describes very di…
The authors report the changes that are included in the revised Standard IEEE-519. In order to better understand what the standard means in practical terms, two applications of the standard are discussed in detail: a large industrial plant furnished at transmission voltage and several users on a single distribution fe…
Sb4: The building block of a new solid-state modification of antimony. This is a somewhat provocative description of the fact that nanocrystalline structures of Sb4 tetrahedrons exist on the substrates AuSb2(100) and MoS2(0001). Scanning tunneling microscopy images (see picture, (a) and (b), respectively, each 39×39 Å…
We studied the charge ordering transition of LiMn 2 O 4 by means of anelastic spectroscopy, measuring the Young’s modulus, E ′ , and the elastic energy loss function, Q −1 . Our measurements confirm the occurrence of a phase transition at 296 K on cooling, showing a large hysteresis on heating. The anelastic spectrosc…
It was observed that a ferroelectric domain boundary (DB) is always accompanied by an antiferromagnetic DB in hexagonal YMnO 3 , by means of interference effects of the second-harmonic signal. The clamping of these two order parameters at the ferroelectric DB is shown theoretically to originate from Dzyaloshinski–Mori…
The discovery of ordered but aperiodic quasicrystal structures has required the development of new diffraction methods to determine their structures. The purpose of this review is to highlight the challenges posed by the aperiodicity of quasicrystals to the study of their surface structures by low-energy electron diff…