19,459 research outputs found
Vehicle test report: Jet Industries Electra Van 600
The Electra Van 600, an electric vehicle, was tested. Tests were performed to characterize parameters of the Electra Van 600 and to provide baseline data to be used for comparison of improved batteries and to which will be incorporated into the vehicle. The vehicle tests concentrated on the electrical drive subsystem, the batteries, controller, and motor; coastdowns to characterize the road load and range evaluation for cyclic and constant speed conditions; and qualitative performance was evaluated. It is found that the Electra Van 600 range performance is approximately equal to the majority of the vehicles tested previously
Vehicle test report: Electric Vehicle Associates electric conversion of an AMC Pacer
Tests were performed to characterize certain parameters of the EVA Pacer and to provide baseline data that can be used for the comparison of improved batteries that may be incorporated into the vehicle at a later time. The vehicle tests were concentrated on the electrical drive subsystem; i.e., the batteries, controller and motor. The tests included coastdowns to characterize the road load, and range evaluations for both cyclic and constant speed conditions. A qualitative evaluation of the vehicle's performance was made by comparing its constant speed range performance with other electric and hybrid vehicles. The Pacer performance was approximately equal to the majority of those vehicles assessed in 1977
Vehicle test report: Electric Vehicle Associates electric conversion of an AMC Pacer
The change of pace, an electric vehicle was tested. These tests were performed to characterize certain parameters of the electric vehicle pacer and to provide baseline data that can be used for the comparison of improved batteries that may be incorporated into the vehicle at a later time. The vehicle tests were concentrated on the electrical drive subsystem, the batteries, controller and motor. Coastdowns to characterize the road load, and range evaluations for both cyclic and constant speed conditions were performed. The vehicle's performance was evaluated by comparing its constant speed range performance with described vehicles. It is found that the pacer performance is approximately equal to the majority of the vehicles tested in the 1977 assessment
Observations of Stellar Objects at a Shell Boundary in the Star-Forming Complex in the Galaxy IC1613
The single region of ongoing star formation in the galaxy IC 1613 has been
observed in order to reveal the nature of compact emission-line objects at the
edges of two shells in the complex, identified earlier in H-alpha line images.
The continuum images show these compact objects to be stars. Detailed
spectroscopic observations of these stars and the surrounding nebulae were
carried out with an integral field spectrograph MPFS mounted on the 6m
telescope of the Special Astrophysical Observatory. The resulting stellar
spectra were used to determine the spectral types and luminosity classes of the
objects. An Of star we identified is the only object of this spectral type in
IC 1613. The results of optical observations of the multi-shell complex are
compared to 21cm radio observations. The shells harboring the stars at their
boundaries constitute the most active part of the star-forming region. There is
evidence that shocks have played an important role in the formation of the
shells.Comment: 10 pages, 5 PS and 1 color JPEG figur
Domain Wall Spin Dynamics in Kagome Antiferromagnets
We report magnetization and neutron scattering measurements down to 60 mK on
a new family of Fe based kagome antiferromagnets, in which a strong local spin
anisotropy combined with a low exchange path network connectivity lead to
domain walls intersecting the kagome planes through strings of free spins.
These produce unfamiliar slow spin dynamics in the ordered phase, evolving from
exchange-released spin-flips towards a cooperative behavior on decreasing the
temperature, probably due to the onset of long-range dipolar interaction. A
domain structure of independent magnetic grains is obtained that could be
generic to other frustrated magnets.Comment: 5 pages, 4 figure
Applying black hole perturbation theory to numerically generated spacetimes
Nonspherical perturbation theory has been necessary to understand the meaning
of radiation in spacetimes generated through fully nonlinear numerical
relativity. Recently, perturbation techniques have been found to be successful
for the time evolution of initial data found by nonlinear methods. Anticipating
that such an approach will prove useful in a variety of problems, we give here
both the practical steps, and a discussion of the underlying theory, for taking
numerically generated data on an initial hypersurface as initial value data and
extracting data that can be considered to be nonspherical perturbations.Comment: 14 pages, revtex3.0, 5 figure
Head-on collisions of black holes: the particle limit
We compute gravitational radiation waveforms, spectra and energies for a
point particle of mass falling from rest at radius into a
Schwarzschild hole of mass . This radiation is found to lowest order in
with the use of a Laplace transform. In contrast with numerical
relativity results for head-on collisions of equal-mass holes, the radiated
energy is found not to be a monotonically increasing function of initial
separation; there is a local radiated-energy maximum at . The
present results, along with results for infall from infinity, provide a
complete catalog of waveforms and spectra for particle infall. We give a
representative sample from that catalog and an interesting observation: Unlike
the simple spectra for other head-on collisions (either of particle and hole,
or of equal mass holes) the spectra for show a series of
evenly spaced bumps. A simple explanation is given for this. Lastly, our energy
vs. results are compared with approximation methods used elsewhere, for
small and for large initial separation.Comment: 15 pages, REVTeX, 25 figure
Conductance Increase by Electron-Phonon Interaction in Quantum Wires
We investigate the influence of electron-phonon interactions on the
DC-conductance of a quantum wire in the limit of one occupied
subband. At zero temperature, a Tomonaga-Luttinger-like renormalization of
to a value slightly larger than is calculated for a
realistic quantum wire model.Comment: 12 pages RevTeX, no figure. Appears in Phys. Rev.
Multi-objective engineering shape optimization using differential evolution interfaced to the Nimrod/O tool
This paper presents an enhancement of the Nimrod/O optimization tool by interfacing DEMO, an external multiobjective optimization algorithm. DEMO is a variant of differential evolution – an algorithm that has attained much popularity in the research community, and this work represents the first time that true multiobjective optimizations have been performed with Nimrod/O. A modification to the DEMO code enables multiple objectives to be evaluated concurrently. With Nimrod/O’s support for parallelism, this can reduce the wall-clock time significantly for compute intensive objective function evaluations. We describe the usage and implementation of the interface and present two optimizations. The first is a two objective mathematical function in which the Pareto front is successfully found after only 30 generations. The second test case is the three-objective shape optimization of a rib-reinforced wall bracket using the Finite Element software, Code_Aster. The interfacing of the already successful packages of Nimrod/O and DEMO yields a solution that we believe can benefit a wide community, both industrial and academic
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