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Institution

General Electric

CompanyBoston, Massachusetts, United States
About: General Electric is a company organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Turbine & Rotor (electric). The organization has 76365 authors who have published 110557 publications receiving 1885108 citations. The organization is also known as: General Electric Company & GE.
Topics: Turbine, Rotor (electric), Signal, Combustor, Coating


Papers
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Journal ArticleDOI
TL;DR: In this paper, the first-order magnetic transition in the absence of magnetic interactions was shown to be of the first order. But the transition was not observed in the case of magnetization with temperature.
Abstract: The exchange interaction that gives rise to ordered magnetic states depends upon interatomic spacing. If the lattice is deformable, then a spontaneous distortion of the lattice will occur in the ordered state. We have calculated, in the molecular field approximation, the properties of a system in which the exchange energy dependence is given by ${T}_{c}={T}_{0}[1+\frac{\ensuremath{\beta}(v\ensuremath{-}{v}_{0})}{{v}_{0}}]$. ${T}_{c}$ is the Curie temperature appropriate to a lattice volume $v$ while ${v}_{0}$ is the equilibrium volume in the absence of magnetic interactions. The course of the magnetization with temperature of such a system depends upon the steepness $\ensuremath{\beta}$ of the exchange interaction dependence on interatomic distance, the compressibility $K$, and ${T}_{0}$. The behavior may be the usual second-order transition to paramagnetism, but it can in fact become a first-order transition with the properties usually associated thereto, e.g., latent heat and discontinuous density change. In the absence of an externally applied pressure, the transition will be of the first order if $\ensuremath{\eta}\ensuremath{\equiv}\frac{40NkK{T}_{0}{\ensuremath{\beta}}^{2}{[j(j+1)]}^{2}}{[{(2j+1)}^{4}\ensuremath{-}1]}g1$. In this inequality, $N$ is the number per unit volume of magnetic ions of angular momentum $j\ensuremath{\hbar}$ while $k$ is the Boltzmann constant.We have reviewed the experimental evidence on the nature of the first-order magnetic transition in MnAs. We find that this evidence indicates the transition to be one from ferromagnetism to paramagnetism rather than ferromagnetism to antiferromagnetism as has been generally assumed. Application of the theory noted above gives $\ensuremath{\eta}=2$ for this transition. In addition, we derive a value for the volume strain sensitivity, $\ensuremath{\beta}=19$ and infer the compressibility to be 2.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{2}$/d.

688 citations

Journal ArticleDOI
TL;DR: In this article, the one-electron (Bethe-Sommerfeld) model of electron tunneling is formulated to describe tunneling when the curvature (electron mass and centroid of the oneelectron constant energy surfaces vary across the junction.
Abstract: The one-electron (Bethe-Sommerfeld) model of electron tunneling is formulated to describe tunneling when the curvature (electron mass) and centroid of the one-electron constant-energy surfaces vary across the junction. The conductance for an abrupt GaAs $p\ensuremath{-}n$ tunnel diode is calculated and shown to exhibit minima near zero bias for highly asymmetrical doping ratios. The conductance of metal-oxide-semimetal (M-O-SM) tunnel junctions is evaluated both with and without the inclusion of space-charge effects and of surface states. All calculations are performed using solvable models for which the WKBJ approximation is not imposed. Neither the removal of the WKBJ approximation nor the space-charge effects give rise to maxima in the conductance of the M-O-SM junctions near a band edge.

684 citations

Journal ArticleDOI
W. L. Roth1
TL;DR: In this paper, the antiferromagnetic arrangement of moments in MnO, FeO, CoO, and NiO have been investigated by powder neutron diffraction and the results for the four oxides are consistent with a structure in which the magnetic moments are arrayed in ferromagnetic sheets parallel to (111) planes, and the direction of magnetization in neighboring planes is antiparallel.
Abstract: The antiferromagnetic arrangement of moments in MnO, FeO, CoO, and NiO have been investigated by powder neutron diffraction. The results for the four oxides are consistent with a structure in which the magnetic moments are arrayed in ferromagnetic sheets parallel to (111) planes, and the direction of magnetization in neighboring planes is antiparallel. The observation of diffuse neutron scattering limits the precision with which the magnetization direction can be specified. If the diffuse intensity is included with the Bragg scattering, the direction of magnetization in MnO, and NiO lies within the (111) plane; for CoO, the preferred direction is [$\overline{1}\overline{1}7$], intermediate to the (111) plane and the tetragonal axis. The magnetic axis in FeO is perpendicular to the ferromagnetic sheet.

680 citations

Journal ArticleDOI
TL;DR: The thermomechanical properties of ‘polymer nanocomposites’ are quantitatively equivalent to the well-documented case of planar polymer films and it is conjecture that the glass-transition process requires that the interphase regions surrounding different particles interact.
Abstract: The thermomechanical responses of polymers, which provide limitations to their practical use, are favourably altered by the addition of trace amounts of a nanofiller. However, the resulting changes in polymer properties are poorly understood, primarily due to the non-uniform spatial distribution of nanoparticles. Here we show that the thermomechanical properties of ‘polymer nanocomposites’ are quantitatively equivalent to the well-documented case of planar polymer films. We quantify this equivalence by drawing a direct analogy between film thickness and an appropriate experimental interparticle spacing. We show that the changes in glass-transition temperature with decreasing interparticle spacing for two filler surface treatments are quantitatively equivalent to the corresponding thin-film data with a non-wetting and a wetting polymer–particle interface. Our results offer new insights into the role of confinement on the glass transition, and we conclude that the mere presence of regions of modified mobility in the vicinity of the particle surfaces, that is, a simple two-layer model, is insufficient to explain our results. Rather, we conjecture that the glass-transition process requires that the interphase regions surrounding different particles interact.

675 citations

Proceedings ArticleDOI
07 Oct 1990
TL;DR: The auxiliary resonant commutated pole (ARCP) as discussed by the authors is a new power converter topology that fully achieves soft switching without increasing primary device voltage or current ratings, and is capable of true pulse-width modulation (PWM) control of each phase.
Abstract: The auxiliary resonant commutated pole (ARCP), a new power converter topology that fully achieves soft switching without increasing primary device voltage or current ratings, is discussed. The ARCP converter is capable of true pulse-width modulation (PWM) control of each phase. The power circuit relies on the addition of an auxiliary triggered resonant commutation circuit or snubber to commutate the inductive load current from a main diode to an active device, allowing a zero voltage turn-off of the main devices. The auxiliary devices operate in a zero current soft switching mode, thereby requiring minimal current turn-off capability. The operation and control of the ARCP converter are discussed. Its performance is analyzed, and a simulation is presented. It is shown that the ARCP converter is capable of operation at elevated switching frequencies (10-30 kHz), high power levels (200-1000 kW), and high conversion efficiencies. the auxiliary devices will typically account for a 20% increase in the total silicon area of a three-phase power converter. >

671 citations


Authors

Showing all 76370 results

NameH-indexPapersCitations
Cornelia M. van Duijn1831030146009
Krzysztof Matyjaszewski1691431128585
Gary H. Glover12948677009
Mark E. Thompson12852777399
Ron Kikinis12668463398
James E. Rothman12535860655
Bo Wang119290584863
Wei Lu111197361911
Harold J. Vinegar10837930430
Peng Wang108167254529
Hans-Joachim Freund10696246693
Carl R. Woese10527256448
William J. Koros10455038676
Thomas A. Lipo10368243110
Gene H. Golub10034257361
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20231
202216
2021415
20201,027
20191,418
20181,862