4,174 research outputs found
Cyclic and constant temperature aging effects on magnetic materials for inverters and converters
Cyclic and constant temperature aging effects on magnetic materials for inverters and converter
Computation of a combined spherical-elastic and viscous-half-space earth model for ice sheet simulation
This report starts by describing the continuum model used by Lingle & Clark
(1985) to approximate the deformation of the earth under changing ice sheet and
ocean loads. That source considers a single ice stream, but we apply their
underlying model to continent-scale ice sheet simulation. Their model combines
Farrell's (1972) elastic spherical earth with a viscous half-space overlain by
an elastic plate lithosphere. The latter half-space model is derivable from
calculations by Cathles (1975). For the elastic spherical earth we use
Farrell's tabulated Green's function, as do Lingle & Clark. For the half-space
model, however, we propose and implement a significantly faster numerical
strategy, a spectral collocation method (Trefethen 2000) based directly on the
Fast Fourier Transform. To verify this method we compare to an integral formula
for a disc load. To compare earth models we build an accumulation history from
a growing similarity solution from (Bueler, et al.~2005) and and simulate the
coupled (ice flow)-(earth deformation) system. In the case of simple isostasy
the exact solution to this system is known. We demonstrate that the magnitudes
of numerical errors made in approximating the ice-earth system are
significantly smaller than pairwise differences between several earth models,
namely, simple isostasy, the current standard model used in ice sheet
simulation (Greve 2001, Hagdorn 2003, Zweck & Huybrechts 2005), and the Lingle
& Clark model. Therefore further efforts to validate different earth models
used in ice sheet simulations are, not surprisingly, worthwhile.Comment: 36 pages, 16 figures, 3 Matlab program
Long-chain omega-3 PUFAs and their role in healthy ageing
The effects of various fat subtypes can have a profound influence on our health and performance, not only in the early years of life but also as we age. The long-chain omega-3s docosahexaenoic and eicosapentaenoic acid appear to have a positive role in our mental and physical health
Solar Particle Acceleration at Reconnecting 3D Null Points
Context: The strong electric fields associated with magnetic reconnection in
solar flares are a plausible mechanism to accelerate populations of high
energy, non-thermal particles. One such reconnection scenario occurs at a 3D
magnetic null point, where global plasma flows give rise to strong currents in
the spine axis or fan plane. Aims: To understand the mechanism of charged
particle energy gain in both the external drift region and the diffusion region
associated with 3D magnetic reconnection. In doing so we evaluate the
efficiency of resistive spine and fan models for particle acceleration, and
find possible observables for each. Method: We use a full orbit test particle
approach to study proton trajectories within electromagnetic fields that are
exact solutions to the steady and incompressible magnetohydrodynamic equations.
We study single particle trajectories and find energy spectra from many
particle simulations. The scaling properties of the accelerated particles with
respect to field and plasma parameters is investigated. Results: For fan
reconnection, strong non-uniform electric drift streamlines can accelerate the
bulk of the test particles. The highest energy gain is for particles that enter
the current sheet, where an increasing "guide field" stabilises particles
against ejection. The energy is only limited by the total electric potential
energy difference across the fan current sheet. The spine model has both slow
external electric drift speed and weak energy gain for particles reaching the
current sheet. Conclusions: The electromagnetic fields of fan reconnection can
accelerate protons to the high energies observed in solar flares, gaining up to
0.1 GeV for anomalous values of resistivity. However, the spine model, which
gave a harder energy spectrum in the ideal case, is not an efficient
accelerator after pressure constraints in the resistive model are included.Comment: 15 pages, 14 figures. Submitted to Astronomy and Astrophysic
Valuation of Child Behavioral Problems from the Perspective of US Adults
To assess preferences between child behavioral problems and estimate their value on a quality-adjusted life year (QALYs) scale
Increased risk donor criteria: The time for change is now
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155965/1/ctr13879.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155965/2/ctr13879_am.pd
The Iowa Crop Management Database: An Agronomic and Economic Information Recording Tool
The Iowa Crop Management Database (CMD) is designed to record field-by-field agronomic and economic information for crop production in Iowa. Iowa State University Extension is promoting use of such comprehensive records by producers and crop consultants to improve management decisions and farm profitability. Extension staff can use this information and summaries of these records in educational programs, and to document pollution prevention through refined crop management practices. The CMD program is a relational database designed on a model first developed by Pennsylvania State University. The Iowa version was expanded and developed to include a wider range of information resources needed by Iowa producers as a result of a cooperative effort between Extension, state agencies, and agribusiness organizations. The program can meet record-keeping needs for field-by-field agronomic planning, economic analysis, and regulatory documentation. The CMD program is being widely advertised in Iowa by newsletters, direct mailing, brochures displayed at ISU Extension offices, over the World Wide Web and on local radio stations. ISU Extension field specialists with responsibilities for crop production and farm management have been trained in the use of the program. ISU Extension Agribusiness Education is offering a one day short course to train CMD program users. The course will be held on December 10, 1997, January 14 & 21, 1998 and February 11, 1998
Koinonia
In This IssueThe Quest for Moral Integrity, James S. Spiegel
The Freshmen Year Experience: A Senior\u27s Perspective, Ryan Hartwig
Around CampusRelationship Emphasis Week, Jesse Brown
Spotlight on ServiceThe Schuberts: Finding Passion on a Journey of Faith, David Craig
Regular FeaturesPresident\u27s Corner
Editor\u27s Disk
Annual Conference: Memories of the ACSD 2000 at Taylor University
Book Review: What Christians Think about Homosexuality
ACSD Business: Placement Services
ACSD Business: Logo Searchhttps://pillars.taylor.edu/acsd_koinonia/1014/thumbnail.jp
Recommended from our members
Complete Genomic Sequences of Three Salmonella enterica subsp. enterica Serovar Muenchen Strains from an Orchard in San Joaquin County, California.
We present here the complete genome sequences of three Salmonella enterica subsp. enterica serovar Muenchen strains, LG24, LG25, and LG26. All three strains were isolated from almond drupes grown in an orchard in San Joaquin County, California, in 2016. These genomic sequences are nonidentical and will contribute to our understanding of S. enterica genomics
- …