9,078 research outputs found
On numerically accurate finite element
A general criterion for testing a mesh with topologically similar repeat units is given, and the analysis shows that only a few conventional element types and arrangements are, or can be made suitable for computations in the fully plastic range. Further, a new variational principle, which can easily and simply be incorporated into an existing finite element program, is presented. This allows accurate computations to be made even for element designs that would not normally be suitable. Numerical results are given for three plane strain problems, namely pure bending of a beam, a thick-walled tube under pressure, and a deep double edge cracked tensile specimen. The effects of various element designs and of the new variational procedure are illustrated. Elastic-plastic computation at finite strain are discussed
Avionics test bed development plan
The plan is for a facility for the early investigation and evaluation of new concepts for the control of large space structures, orbiter attached flex body experiments, and orbiter enhancements. This plan outlines a distributed data processing facility that will utilize the current JSC laboratory resources for the test bed development. The future studies required for implementation, the management system for project control, and the baseline system configuration are described
Avionics test bed development plan
A development plan for a proposed avionics test bed facility for the early investigation and evaluation of new concepts for the control of large space structures, orbiter attached flex body experiments, and orbiter enhancements is presented. A distributed data processing facility that utilizes the current laboratory resources for the test bed development is outlined. Future studies required for implementation, the management system for project control, and the baseline system configuration are defined. A background analysis of the specific hardware system for the preliminary baseline avionics test bed system is included
Polar orbit electrostatic charging of objects in shuttle wake
A survey of DMSP data has uncovered several cases where precipitating auroral electron fluxes are both sufficiently intense and energetic to charge spacecraft materials such as teflon to very large potentials in the absence of ambient ion currents. Analytical bounds are provided which show that these measured environments can cause surface potentials in excess of several hundred volts to develop on objects in the orbiter wake for particular vehicle orientations
A feasibility study: California Department of Forestry and Fire Protection utilization of infrared technologies for wildland fire suppression and management
NASA's JPL has completed a feasibility study using infrared technologies for wildland fire suppression and management. The study surveyed user needs, examined available technologies, matched the user needs with technologies, and defined an integrated infrared wildland fire mapping concept system configuration. System component trade-offs were presented for evaluation in the concept system configuration. The economic benefits of using infrared technologies in fire suppression and management were examined. Follow-on concept system configuration development and implementation were proposed
Extracting joint weak values with local, single-particle measurements
Weak measurement is a new technique which allows one to describe the
evolution of postselected quantum systems. It appears to be useful for
resolving a variety of thorny quantum paradoxes, particularly when used to
study properties of pairs of particles. Unfortunately, such nonlocal or joint
observables often prove difficult to measure weakly in practice (for instance,
in optics -- a common testing ground for this technique -- strong photon-photon
interactions would be needed). Here we derive a general, experimentally
feasible, method for extracting these values from correlations between
single-particle observables.Comment: 6 page
Thermodynamic properties of Bi2Sr2CaCu2O8 calculated from the electronic dispersion
The electronic dispersion for Bi2Sr2CaCu2O(8+d) has been determined from
angle-resolved photoelectron spectroscopy (ARPES). From this dispersion we
calculate the entropy and superfluid density. Even with no adjustable
parameters we obtain an exceptional match with experimental data across the
entire phase diagram, thus indirectly confirming both the ARPES and
thermodynamic data. The van Hove singularity is crossed in the overdoped region
giving a distinctive linear-in-T temperature dependence in the superfluid
density there.Comment: 5 pages, 4 figures, submitted to Physical Review Letter
Holographic Superconductors with Ho\v{r}ava-Lifshitz Black Holes
We discuss the phase transition of planar black holes in Ho\v{r}ava-Lifshitz
gravity by introducing a Maxwell field and a complex scalar field. We calculate
the condensates of the charged operators in the dual CFTs when the mass square
of the complex scalar filed is and , respectively. We
compute the electrical conductivity of the \hl superconductor in the probe
approximation. In particular, it is found that there exists a spike in the
conductivity for the case of the operator with scaling dimension one. These
results are quite similar to those in the case of Schwarzschild-AdS black
holes, which demonstrates that the holographic superconductivity is a robust
phenomenon associated with asymptotic AdS black holes.Comment: 12 pages, 7 figures,refs adde
Analysis of the charging of the SCATHA (P78-2) satellite
The charging of a large object in polar Earth orbit was investigated in order to obtain a preliminary indication of the response of the shuttle orbiter to such an environment. Two NASCAP (NASA Charging Analyzer Program) models of SCATHA (Satellite Charging at High Altitudes) were used in simulations of charging events. The properties of the satellite's constituent materials were compiled and representations of the experimentally observed plasma spectra were constructed. Actual charging events, as well as those using test environments, were simulated. Numerical models for the simulation of particle emitters and detectors were used to analyze the operation of these devices onboard SCATHA. The effect of highly charged surface regions on the charging conductivity within a photosheath was used to interpret results from the onboard electric field experiment. Shadowing calculations were carried out for the satellite and a table of effective illuminated areas was compiled
Development of mainshaft seals for advanced air breathing propulsion systems, phase 1 Final report, 25 Jun. 1965 - 25 Jul. 1967
Comparison of gas film mainshaft seals with rubbing contract seals for high temperature, high speed, and high pressure gas turbine application
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