11,324 research outputs found
Flat conductor cable survey
Design handbook contains data and illustrations concerned with commercial and Government flat-conductor-cable connecting and terminating hardware. Material was obtained from a NASA-sponsored industry-wide survey of approximately 150 companies and Government agencies
A linearized kinetic theory of spin-1/2 particles in magnetized plasmas
We have considered linear kinetic theory including the electron spin
properties in a magnetized plasma. The starting point is a mean field
Vlasov-like equation, derived from a fully quantum mechanical treatment, where
effects from the electron spin precession and the magnetic dipole force is
taken into account. The general conductivity tensor is derived, including both
the free current contribution, as well as the magnetization current associated
with the spin contribution. We conclude the paper with an extensive discussion
of the quantum-mechanical boundary where we list parameter conditions that must
be satisfied for various quantum effects to be influential.Comment: 11 page
Applications of FEM and BEM in two-dimensional fracture mechanics problems
A comparison of the finite element method (FEM) and boundary element method (BEM) for the solution of two-dimensional plane strain problems in fracture mechanics is presented in this paper. Stress intensity factors (SIF's) were calculated using both methods for elastic plates with either a single-edge crack or an inclined-edge crack. In particular, two currently available programs, ANSYS for finite element analysis and BEASY for boundary element analysis, were used
Frame synchronization performance and analysis
The analysis used to generate the theoretical models showing the performance of the frame synchronizer is described for various frame lengths and marker lengths at various signal to noise ratios and bit error tolerances
Conductivity in Jurkat cell suspension after ultrashort electric pulsing
Ultrashort electric pulses applied to similar cell lines such as Jurkat and HL-60 cells can produce markedly different results , which have been documented extensively over the last few years. We now report changes in electrical conductivity of Jurkat cells subjected to traditional electroporation pulses (50 ms pulse length) and ultrashort pulses (10 ns pulse length) using time domain dielectric spectroscopy (TDS). A single 10 ns, 150 kV/cm pulse did not noticeably alter suspension conductivity while a 50 ms, 2.12 kV/cm pulse with the same energy caused an appreciable conductivity rise. These results support the hypothesis that electroporation pulses primarily interact with the cell membrane and cause conductivity rises due to ion transport from the cell to the external media, while pulses with nanosecond duration primarily interact with the membranes of intracellular organelles. However, multiple ultrashort pulses have a cumulative effect on the plasma membrane, with five pulses causing a gradual rise in conductivity up to ten minutes post-pulsing
Preliminary design characteristics of a subsonic business jet concept employing an aspect ratio 25 strut braced wing
The advantages of replacing the conventional wing on a transatlantic business jet with a larger, strut braced wing of aspect ratio 25 were evaluated. The lifting struts reduce both the induced drag and structural weight of the heavier, high aspect ratio wing. Compared to the conventional airplane, the strut braced wing design offers significantly higher lift to drag ratios achieved at higher lift coefficients and, consequently, a combination of lower speeds and higher altitudes. The strut braced wing airplane provides fuel savings with an attendant increase in construction costs
Inflation Assisted by Heterotic Axions
We explore the possibility of obtaining inflation in weakly coupled heterotic
string theory, where the model dependent axions are responsible for driving
inflation. This model can be considered as a certain extrapolation of
-inflation, and is an attempt to explicitly realize the so
called N-flation proposal in string theory. The instanton generated potential
for the axions essentially has two parameters; a natural mass scale and the
string coupling . For isotropic compactifications leading to of order
axions in the four dimensional spectrum we find that with
the observed temperature fluctuations in the
CMB are correctly reproduced. We assume an initially random distribution for
the vevs of the axions. The spectral index, , is generically more red
than for -inflation. The greater the vevs, the more red the
spectral index becomes. Allowing for a wide range of vevs 55 -foldings from
the end of inflation, we find . The
tensor-to-scalar ratio, , is more sensitive to the vevs, but typically
smaller than in -inflation. Furthermore, in the regime where the
leading order theory is valid, is bounded by . The spectral index
and the tensor-to-scalar ratio are correlated. For example,
corresponds to .Comment: 1+21 pages, 2 figures, v2: Typos corrected, v3: Typos, very minor
corrections, reference added, to appear in JCA
Effects of the -factor in semi-classical kinetic plasma theory
A kinetic theory for spin plasmas is put forward, generalizing those of
previous authors. In the model, the ordinary phase space is extended to include
the spin degrees of freedom. Together with Maxwell's equations, the system is
shown to be energy conserving. Analysing the linear properties, it is found
that new types of wave-particle resonances are possible, that depend directly
on the anomalous magnetic moment of the electron. As a result new wave modes,
not present in the absence of spin, appear. The implications of our results are
discussed.Comment: 4 pages, two figures, version to appear in Physical Review Letter
Energy management study for lunar oxygen production
Energy management opportunities in the process of hydrogen reduction of ilmenite for lunar oxygen production are being investigated. An optimal energy system to supply the power requirements for the process will be determined
Circular 64
Treatment of Alaska-produced food products by ionizing radiation may
benefit the seafood and agricultural industries and the Alaskan consumer. A
feasibility study to evaluate the potential social and economic benefits and
risks as well as the costs of using the process in Alaska on Alaskan products is being coordinated
by the Institute of Northern Engineering. A research and development project to determine
effects on the quality o f Alaskan products could be the next phase in the introduction o f a new
food-preservation technique
to Alaska
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