59,766 research outputs found
Graphical method for analyzing digital computer efficiency
Analysis method utilizes graph-theoretic approach for evaluating computation cost and makes logical distinction between linear graph of a computation and linear graph of a program. It applies equally well to other processes which depend on quatitative edge nomenclature and precedence relationships between edges
A topological approach to computer-aided sensitivity analysis
Sensitivities of any arbitrary system are calculated using general purpose digital computer with available software packages for transfer function analysis. Sensitivity shows how element variation within system affects system performance. Signal flow graph illustrates topological system behavior and relationship among parameters in system
Efficiency in the use of a computer for network analysis
Efficiency in use of digital computer for network analysi
Effects of Electromagnetic Field on the Dynamical Instability of Cylindrical Collapse
The objective of this paper is to discuss the dynamical instability in the
context of Newtonian and post Newtonian regimes. For this purpose, we consider
non-viscous heat conducting charged isotropic fluid as a collapsing matter with
cylindrical symmetry. Darmois junction conditions are formulated. The
perturbation scheme is applied to investigate the influence of dissipation and
electromagnetic field on the dynamical instability. We conclude that the
adiabatic index has smaller value for such a fluid in cylindrically
symmetric than isotropic sphere
Adsorbate Electric Fields on a Cryogenic Atom Chip
We investigate the behaviour of electric fields originating from adsorbates
deposited on a cryogenic atom chip as it is cooled from room temperature to
cryogenic temperature. Using Rydberg electromagnetically induced transparency
we measure the field strength versus distance from a 1 mm square of YBCO
patterned onto a YSZ chip substrate. We find a localized and stable dipole
field at room temperature and attribute it to a saturated layer of chemically
adsorbed rubidium atoms on the YBCO. As the chip is cooled towards 83 K we
observe a change in sign of the electric field as well as a transition from a
localized to a delocalized dipole density. We relate these changes to the onset
of physisorption on the chip surface when the van der Waals attraction
overcomes the thermal desorption mechanisms. Our findings suggest that, through
careful selection of substrate materials, it may be possible to reduce the
electric fields caused by atomic adsorption on chips, opening up experiments to
controlled Rydberg-surface coupling schemes.Comment: 5 pages, 4 figure
Effects of f(R) Model on the Dynamical Instability of Expansionfree Gravitational Collapse
Dark energy models based on f(R) theory have been extensively studied in
literature to realize the late time acceleration. In this paper, we have chosen
a viable f(R) model and discussed its effects on the dynamical instability of
expansionfree fluid evolution generating a central vacuum cavity. For this
purpose, contracted Bianchi identities are obtained for both the usual matter
as well as dark source. The term dark source is named to the higher order
curvature corrections arising from f(R) gravity. The perturbation scheme is
applied and different terms belonging to Newtonian and post Newtonian regimes
are identified. It is found that instability range of expansionfree fluid on
external boundary as well as on internal vacuum cavity is independent of
adiabatic index but depends upon the density profile, pressure
anisotropy and f(R) model.Comment: 26 pages, no figure. arXiv admin note: text overlap with
arXiv:1108.266
Unified constitutive models for high-temperature structural applications
Unified constitutive models are characterized by the use of a single inelastic strain rate term for treating all aspects of inelastic deformation, including plasticity, creep, and stress relaxation under monotonic or cyclic loading. The structure of this class of constitutive theory pertinent for high temperature structural applications is first outlined and discussed. The effectiveness of the unified approach for representing high temperature deformation of Ni-base alloys is then evaluated by extensive comparison of experimental data and predictions of the Bodner-Partom and the Walker models. The use of the unified approach for hot section structural component analyses is demonstrated by applying the Walker model in finite element analyses of a benchmark notch problem and a turbine blade problem
Reconfigurable self-sufficient traps for ultracold atoms based on a superconducting square
We report on the trapping of ultracold atoms in the magnetic field formed
entirely by persistent supercurrents induced in a thin film type-II
superconducting square. The supercurrents are carried by vortices induced in
the 2D structure by applying two magnetic field pulses of varying amplitude
perpendicular to its surface. This results in a self-sufficient quadrupole trap
that does not require any externally applied fields. We investigate the
trapping parameters for different supercurrent distributions. Furthermore, to
demonstrate possible applications of these types of supercurrent traps we show
how a central quadrupole trap can be split into four traps by the use of a bias
field.Comment: 5 pages, 7 figure
Conservation of statistical results under the reduction of pair-contact interactions to solvation interactions
We show that the hydrophobicity of sequences is the leading term in
Miyazawa-Jernigan interactions. Being the source of additive (solvation) terms
in pair-contact interactions, they were used to reduce the energy parameters
while resulting in a clear vector manipulation of energy. The reduced
(additive) potential performs considerably successful in predicting the
statistical properties of arbitrary structures. The evaluated designabilities
of the structures by both models are highly correlated. Suggesting
geometrically non-degenerate vectors (structures) as protein-like structures,
the additive model is a powerful tool for protein design. Moreover, a crossing
point in the log-linear diagram of designability-ranking shows that about 1/e
of the structures have designabilities above the average, independent on the
used model.Comment: 17 pages and 10 figure
Three-dimensional finite element analysis for high velocity impact
A finite element algorithm for solving unsteady, three-dimensional high velocity impact problems is presented. A computer program was developed based on the Eulerian hydroelasto-viscoplastic formulation and the utilization of the theorem of weak solutions. The equations solved consist of conservation of mass, momentum, and energy, equation of state, and appropriate constitutive equations. The solution technique is a time-dependent finite element analysis utilizing three-dimensional isoparametric elements, in conjunction with a generalized two-step time integration scheme. The developed code was demonstrated by solving one-dimensional as well as three-dimensional impact problems for both the inviscid hydrodynamic model and the hydroelasto-viscoplastic model
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