Materials Literature
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Many power system circuits contain iron cored coils, which are common nonlinear circuit elements. Systems engineers have to model these elements while studying such phenomena as inrush current, ferroresonance, subharmonics etc. The nonlinearity involved in these elements cannot be appropriately taken into account unle…
A method for computing transient eddy currents induced by the movement of magnets without iron materials, such as superconducting magnets, is proposed. The formulation is based on a finite-difference method utilizing only the electric vector potential of the T- Omega method. Meshing is done only for the 2-D thin condu…
Thirty-five papers presented at the University of Wales Institute of Science and Technology, Cardiff, UK Sept. 1987 conference discuss recent results and developments in thermoelectric energy conversion under the topics: general properties and behavior, measurement, applications, conversion. Annotat
The magnetomechanical behavior of ferromagnetic material is analyzed. The behavior is nonlinear because of the strong nonlinear B-H magnetization relation. Finite-element analyses of 2-D and 3-D magnetic field, magnetic torque, and deformation of a beam-plate arrangement and a circular tube are described. Experimental…
Conversion of the octaethyl-11-oxochlarin and octaethyl-7.17-dioXoisobacterioch10rininto their thio and dithio analogs using Lawesson's reagent is reported.Spectroscopic data, along with X-ray crystallographic data for the dithio compound and its dloxo precursor, are reported.Porphyrins and porphyrin derivatives beari…
MNDO and extended Hückel calculations on the electronic structure of BC3 based on structure (1) and the alternatives (2) and (3) suggest that (1) would be an insulator rather than show metallic conductivity but that structures (2) and (3) could explain its high conductivity.
Moxa was soaked in a mixed solvent of chloroform, methanol and water (5:5:1) at room temperature for 7 days, and the supernatant solution was separated into two layers by the addition of water. Heptatriacontane (C37H76), confirmed by measurements of 1H and 13C-NMR spectra and melting point, was obtained from the chlor…
A treatment which significantly increases the pulsed surface flashover potential of some insulator materials in vacuum is described. The flashover potential is measured by placing a short cylindrical sample between brass electrodes in a vacuum chamber at a pressure of 10/sup -4/ Pa and applying a high-voltage (HV) dou…
Space power requirements for future NASA and other United States missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into o…
The various attributes of copper alloys and stainless steels for use in sea water handling systems have been compared. As an outcome of this, a 4-year test program was undertaken to establish the corrosion characteristics of various stainless steel alloys in their cast and wrought forms. To facilitate this work, a ful…
In the anhydrous crystal the discoid amphiphile TP6E02M (1) packs in tilted columns whereas in the more hydrated liquid crystal phases these columns are vertical.
The interface of a nematic 7CB - solid substrate has been studied by optical ellipsometry. The phase difference between 0 and E rays, Δ = δ p - δs, and the angle ψ = tan-1 | r p/rs | are measured as a function of incidence angle and temperature. To fit the experimental data, an exponential interfacial region having a…
After suitable thermomechanical treatment a series of Cu-based and Ni-Ti-alloys can show a reversible shape change during heating and/or cooling over a temperature region of about 40 degrees. Two important conditions for this effect are that a thermoelastic martensitic transformation occurs in this temperature range a…
Résumé.- Le formalisme de la mécanique des milieux continus est discuté pour l’analyse des insta-bilités par striction et par bandes. L’apparition de l’instabilité que l’on prédit dépend forte-ment des caractéristiques des matériaux, pas seulement à travers les propriétés comme le durcisse-ment par écrouissage ou la s…
The passivity of metals is reviewed from the perspective of materials science rather than with the usual electrochemical emphasis. Iron and ferrous alloys are used to illustrate the essentials of the phenomenon of passivity. A discussion of the general and engineering aspects is first given followed by a detailed desc…
Three new pyridoxine-glycosides were isolated from rice bran (10 kg) as colorless powder by various chromatographic techniques: compound A, 53 mg; compound B, 7.8 mg; compound C, 5.8 mg. Compound A was shown to consist of pyridoxine and glucose in a 1:2 molar ratio by beta-glucosidase hydrolysis, and by 1H-NMR and sec…
Combined tension/torsion and compression/torsion tests for sintered silicon nitride specimens were carried out at room temperature to investigate the fracture behavior of ceramics under multiaxial stress states. Tension, torsion and 4-point bending tests have been also carried out in order to estimate Weibull's two pa…
Eight bisdesmosidic pregnane glycosides were isolated from Trachelospermum asiaticum NAKAI (Apocynaceae). The glycosides have a common structure of 3-O-β-D-digitalosyl-3β, 17α, 20α-trihydroxy-5α-pregn-6-ene, and three sugars at most are linked to the 20-hydroxyl group.
A simple emprical expression for temperature dependence of liquid viscosity, which carries two adjustable parameters and includes a glass transition temperature, Tg, and the liquid viscosity ηg at Tg, has been proposed in the form :log(η/ηg)=A[exp{B(Tg-T)/T}-1]This expression has been applied to 14 liquids including p…
A method of calculating the temperature rise in the core, conductors, insulation, and cooling air of the stator and rotor of a salient pole alternator is described, with emphasis on the development of a finite-difference model of sufficiently reduced complexity to allow reasonably economic computation. The electrical…