80,527 research outputs found
Magnetic Properties of a Two-Dimensional Mixed-Spin System
Using a Langmuir-Blodgett (LB) synthesis method, novel two-dimensional (2D)
mixed-spin magnetic systems, in which each magnetic layer is both structurally
and magnetically isolated, have been generated. Specifically, a 2D Fe-Ni
cyanide-bridged network with a face-centered square grid structure has been
magnetically and structurally characterized. The results indicate the presence
of ferromagnetic exchange interactions between the Fe () and
Ni (S=1) centers.Comment: 2 pages, 3 figs., submitted 23rd International Conference on Low
Temperature Physics (LT-23), Aug. 200
Density Expansion for the Mobility in a Quantum Lorentz Model
We consider the mobility of electrons in an environment of static hard-sphere
scatterers, which provides a realistic description of electrons in Helium gas.
A systematic expansion in the scatterer density is carried to second order
relative to the Boltzmann result, and the analytic contribution at this order
is derived, together with the known logarithmic term in the density expansion.
It is shown that existing experimental data are consistent with the existence
of the logarithmic term in the density expansion, but more precise experiments
are needed in order to unambiguously detect it. We show that our calculations
provide the necessary theoretical information for such an experiment, and give
a detailed discussion of a suitable parameter range.Comment: 17pp., REVTeX, 7 figure attached as 8 postscript files, db/94/
16 x 25 Ge:Ga Detector Arrays for FIFI LS
We are developing two-dimensional 16 x 25 pixel detector arrays of both
unstressed and stressed Ge:Ga photoconductive detectors for far-infrared
astronomy from SOFIA. The arrays, based on earlier 5 x 5 detector arrays used
on the KAO, will be for our new instrument, the Far Infrared Field Imaging Line
Spectrometer (FIFI LS). The unstressed Ge:Ga detector array will cover the
wavelength range from 40 to 120 microns, and the stressed Ge:Ga detector array
from 120 to 210 microns. The detector arrays will be operated with multiplexed
integrating amplifiers with cryogenic readout electronics located close to the
detector arrays. The design of the stressed detector array and results of
current measurements on several prototype 16 pixel linear arrays are reported.
They demonstrate the feasibility of the current concept. ***This paper does not
include Figures due to astro-ph size limitations. Please download entire file
at http://fifi-ls.mpe-garching.mpg.de/spie.det.ps.gz ***Comment: 8 pages, SPIE Proceedings, Astronomical Telescopes and
Instrumentation 200
Applicability valuation for evaluation of surface deflection in automotive outer panels
Upon unloading in a forming process there is elastic recovery, which is the release of the elastic strains and the redistribution of the residual stresses through the thickness direction, thus producing surface deflection. It causes changes in shape and dimensions that can create major problem in the external appearance of outer panels. Thus surface deflection prediction is an important issue in sheet metal forming industry. Many factors could affect surface deflection in the process, such as material variations in mechanical properties, sheet thickness, tool geometry, processing parameters and lubricant condition. The shape and dimension problem in press forming is defined as a trouble mainly caused by the elastic recovery of materials during the forming. The use of high strength steel sheets in the manufacturing of automobile outer panels has increased in the automotive industry over the years because of its lightweight and fuel-efficient improvement. But one of the major concerns of stamping is surface deflection in the formed outer panels. Hence, to be cost effective, accurate prediction must be made of its formability. The automotive industry places rigi
Virtual Investment Concepts and the Ethanol Industry
The fast-growing US ethanol industry has historically been characterized by large downstream investments made by farmers. The authors assess the value which the stock market may hold for downstream investment by farmers as well as by ethanol manufacturers themselves. The model framework used herein expands on the original VEST framework developed by Siebert, Jones and Sporleder. A word of caution, the model herein is not intended to provide an on-going, risk-reducing business strategy. However, it can and does provide a quick method to calculate the reasonableness of a downstream investment request that a farmer (or any business person) might be challenged to consider. Although virtual stock market investments may certainly assist in value added performance, they (just like brick and mortar processing plants) can provide no guarantee of performance.cooperatives, corn, equities, ethanol, value added, Resource /Energy Economics and Policy, Q10, Q32,
- …