2,432 research outputs found
A new behavioural model for performance evaluation of common mode chokes
A galvanically isolated three-phase AC/AC converter with a high-frequency AC-link has been analyzed from an EMC point of view. This is a special configuration because of a large number of switches, a high frequency transformer, and a fourwire output. The essential coupling paths are identified.
Corresponding suppression remedies are given. The results, before and after measures, have been presented to demonstrate the improvement in EMC.
Keywords: AC/AC converter; electromagnetic interference; galvanically isolate
Rare-earthâgalliumâiron glasses. II. Anomalous magnetic hysteresis in alloys based on Pr, Nd, and Sm
Giant magnetic coercivity is reported in several metallic glasses of the form (R80G20)100-xFex where R represents Pr, Nd, or Sm, G represents Ga or Au, and 15â€xâ€30. An unusual temperature variation of the coercive field is observed showing peaks at intermediate temperatures (â90 K). In contrast to similar glasses based on heavy rare-earth metals, these glasses exhibit significant chemical short-range order and even phase separation as is shown by the Mössbauer effect and other measurements. The results are consistent with a recent theory which predicts that large coercivity can result from the presence of site-to-site variations in magnetic properties
Magnetic properties and switching volumes of nanocrystalline SmFeSiC films
Systematic studies of the effects of Si addition on the magnetic and magnetization reversal properties of SmFeSiC films are presented. The magnetic switching volume and other magnetic parameters (e.g., coercivity) are strongly dependent upon the Si content. Correlations between switching volume, coercivity, and the intergrain interactions are discussed
Aerosol number-to-volume-relationship and relative humidity in the eastern Atlantic
J. Geophys. Res ., 105, 1987-1995.Measurementsa cquiredf rom the Office of Naval Research( ONR) Pelican research
aircraftd uringt he secondA erosolC haracterizationE xperiment( ACE 2) are analyzedt o derive
valuesf or the dry (RH = 40%) aerosonl umber-to-volumrea tio in the submicrons izer ange. This
ratioi s foundto ber elativelyc onstanwt,i tha meanv alueo f 168_ +2 1 gm- 3,i n agreemenwti th
previouss tudiese lsewhere.T he impacto f ambientr elativeh umidity (RH) on the dry
number-to-volumies alsoq uantifieda nd a procedurefo r estimatingth e dry from the ambientr atio
established.F inally, the feasibilityo f a remoter etrievalo f the aerosoln umberc oncentrationin
the submicrons izer ange,e ssentiallyth e cloudc ondensation ucleusc oncentrationa ctive at a
nominal0 .2% supersaturationis, partially assessed
Time--Distance Helioseismology Data Analysis Pipeline for Helioseismic and Magnetic Imager onboard Solar Dynamics Observatory (SDO/HMI) and Its Initial Results
The Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory
(SDO/HMI) provides continuous full-disk observations of solar oscillations. We
develop a data-analysis pipeline based on the time-distance helioseismology
method to measure acoustic travel times using HMI Doppler-shift observations,
and infer solar interior properties by inverting these measurements. The
pipeline is used for routine production of near-real-time full-disk maps of
subsurface wave-speed perturbations and horizontal flow velocities for depths
ranging from 0 to 20 Mm, every eight hours. In addition, Carrington synoptic
maps for the subsurface properties are made from these full-disk maps. The
pipeline can also be used for selected target areas and time periods. We
explain details of the pipeline organization and procedures, including
processing of the HMI Doppler observations, measurements of the travel times,
inversions, and constructions of the full-disk and synoptic maps. Some initial
results from the pipeline, including full-disk flow maps, sunspot subsurface
flow fields, and the interior rotation and meridional flow speeds, are
presented.Comment: Accepted by Solar Physics topical issue 'Solar Dynamics Observatory
Holstein polarons in a strong electric field: delocalized and stretched states
The coherent dynamics of a Holstein polaron in strong electric fields is
considered under different regimes. Using analytical and numerical analysis, we
show that even for small hopping constant and weak electron-phonon interaction,
the original discrete Wannier-Stark (WS) ladder electronic states are each
replaced by a semi-continuous band if a resonance condition is satisfied
between the phonon frequency and the ladder spacing. In this regime, the
original localized WS states can become {\em delocalized}, yielding both
`tunneling' and `stretched' polarons. The transport properties of such a system
would exhibit a modulation of the phonon replicas in typical tunneling
experiments. The modulation will reflect the complex spectra with
nearly-fractal structure of the semi-continuous band. In the off-resonance
regime, the WS ladder is strongly deformed, although the states are still
localized to a degree which depends on the detuning: Both the spacing between
the levels in the deformed ladder and the localization length of the resulting
eigenfunctions can be adjusted by the applied electric field. We also discuss
the regime beyond small hopping constant and weak coupling, and find an
interesting mapping to that limit via the Lang-Firsov transformation, which
allows one to extend the region of validity of the analysis.Comment: 10 pages, 13 figures, submitted to PR
Marketing to Liminal Consumers:Migrant Workers as an Emerging Segment in Transitional Economies
Though most acculturation research investigates movement across national boundaries, many other types of boundaries may exist (e.g. rural to urban migration). Rural migrant workers focus on their adaptive and exploratory consumption practices to assemble a liquid identity in China. In essence, this research examines the nature of the transitions that the vast group of Chinese (over 280 million) endures as migrant workers seek to assemble new identities through consumption activities in a liminal space. We find that family relations and government policy hinder migrantsâ adjustments to urban life. Thus, we contribute to macromarketing by enriching the theories of liquid identity, boundary work, and acculturation
Observation and Modeling of the Solar-Cycle Variation of the Meridional Flow
We present independent observations of the solar-cycle variation of flows
near the solar surface and at a depth of about 60 Mm, in the latitude range
. We show that the time-varying components of the meridional flow
at these two depths have opposite sign, while the time-varying components of
the zonal flow are in phase. This is in agreement with previous results. We
then investigate whether the observations are consistent with a theoretical
model of solar-cycle dependent meridional circulation based on a flux-transport
dynamo combined with a geostrophic flow caused by increased radiative loss in
the active region belt (the only existing quantitative model). We find that the
model and the data are in qualitative agreement, although the amplitude of the
solar-cycle variation of the meridional flow at 60 Mm is underestimated by the
model.Comment: To be published in Solar Physcis Topical Issue "Helioseismology,
Asteroseismology, and MHD Connections
Sulfur-doped graphene with iron pyrite (FeS 2 ) as an efficient and stable electrocatalyst for the iodine reduction reaction in dye-sensitized solar cells
As an alternative to platinum (Pt), hybrid electrocatalysts based on sulfur-doped graphene with FeS2 microspheres (SGN-FeS2) were used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Benefiting from the high conductivity of SGN and excellent electrocatalytic activity of the FeS2, the bifunctional hybrid electrocatalyst-based device displays a power conversion efficiency (PCE) of 8.1%, which is comparable to that (8.3%) of traditional Pt CE-based DSSC, while also exhibiting excellent stability in ambient conditions. These characteristics, in addition to its low-cost and facile preparation, make the SGNâFeS2 hybrid an ideal CE material for DSSCs
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