17,877 research outputs found
Metal alloy resistivity measurements at very low temperatures
High speed, automated system accurately measures to approximately one percent in three minutes. System identifies materials having constant thermal or electric conductivity, predicts new material properties, develops alloys in accordance with desired specifications, and develops nondestructive devices for measuring precipitation hardening
Effects of spacecraft reflections on RF interferometer position location accuracy
This report describes one of three study tasks related to the application of an RF interferometer aboard a low-orbiting spacecraft to determine the location of ground-based transmitters. Computer modeling was used to estimate the error in the measured signal angle-of-arrival caused by reflection and diffraction off the spacecraft. Existing computer codes (NEC-BSC) were modified and used to determine the perturbation, due to the spacecraft, in the phase difference between two interferometer antennas, suspended on either side of the spacecraft. This phase perturbation was found as a function of the angle-of-arrival of the signal from a far-field source. The spacecraft antennas were assumed to be circularly polarized with a cardioid pattern. It was found that the perturbation was as much 12.4 deg within the + or - 60 deg field-of-view. This suggests that phase calibration and correction of phase measurements are essential for precision position location using this technique
Observation of Single Transits in Supercooled Monatomic Liquids
A transit is the motion of a system from one many-particle potential energy
valley to another. We report the observation of transits in molecular dynamics
(MD) calculations of supercooled liquid argon and sodium. Each transit is a
correlated simultaneous shift in the equilibrium positions of a small local
group of particles, as revealed in the fluctuating graphs of the particle
coordinates versus time. This is the first reported direct observation of
transit motion in a monatomic liquid in thermal equilibrium. We found transits
involving 2 to 11 particles, having mean shift in equilibrium position on the
order of 0.4 R_1 in argon and 0.25 R_1 in sodium, where R_1 is the nearest
neighbor distance. The time it takes for a transit to occur is approximately
one mean vibrational period, confirming that transits are fast.Comment: 19 pages, 8 figure
Financial, Managerial, and Attitudinal Characteristics of North Dakota Farm Families: Results of the 1986 Farm Survey
Agricultural Finance, Farm Management,
Fast track children's hearing pilot: final report of the evaluation of the pilot
This report presents key findings of the evaluation of the Fast Track children’s hearings pilot in Scotland1. The research was undertaken by staff at the Universities of Glasgow, Stirling and Strathclyde between February 2003 and January 2005
Null Faraday rotation-a clean method for determination of relaxation times and effective masses in MIS and other systems
We determine the relation between photon, cyclotron, collision, and plasma frequencies which ensures a null Faraday rotation for electromagnetic wave propagation in a free-carrier magnetoplasma. This provides a clean determination (in the sense that it is independent of multiple reflections and the length of the plasma along the beam direction) of scattering times and effective masses in MIS and other systems. © 1981
Effects of waterlogging on crop and pasture production in the Upper Great Southern, Western Australia
Separate estimates of the effect of waterlogging on cereal yields were made using rainfall and crop yield statistics, and remote sensing. Both methods showed that waterlogging costs tens of millions of dollars each year in lost crop production in the Upper Great Southern Statistical Division. The costs will be over $100 m in wet years. Losses in pasture production are likely to be of a similar magnitude, but are harder to quantify
Consistent thermodynamic derivative estimates for tabular equations of state
Numerical simulations of compressible fluid flows require an equation of
state (EOS) to relate the thermodynamic variables of density, internal energy,
temperature, and pressure. A valid EOS must satisfy the thermodynamic
conditions of consistency (derivation from a free energy) and stability
(positive sound speed squared). When phase transitions are significant, the EOS
is complicated and can only be specified in a table. For tabular EOS's such as
SESAME from Los Alamos National Laboratory, the consistency and stability
conditions take the form of a differential equation relating the derivatives of
pressure and energy as functions of temperature and density, along with
positivity constraints. Typical software interfaces to such tables based on
polynomial or rational interpolants compute derivatives of pressure and energy
and may enforce the stability conditions, but do not enforce the consistency
condition and its derivatives. We describe a new type of table interface based
on a constrained local least squares regression technique. It is applied to
several SESAME EOS's showing how the consistency condition can be satisfied to
round-off while computing first and second derivatives with demonstrated
second-order convergence. An improvement of 14 orders of magnitude over
conventional derivatives is demonstrated, although the new method is apparently
two orders of magnitude slower, due to the fact that every evaluation requires
solving an 11-dimensional nonlinear system.Comment: 29 pages, 9 figures, 16 references, submitted to Phys Rev
New light on the ‘Drummer of Tedworth’: conflicting narratives of witchcraft in Restoration England
This paper presents a definitive text of hitherto little-known early documents concerning ‘The Drummer of Tedworth’, a poltergeist case that occurred in 1662-3 and became famous not least due to its promotion by Joseph Glanvill in his demonological work, Saducismus Triumphatus. On the basis of these and other sources, it is shown how responses to the events at Tedworth evolved from anxious piety on the part of their victim, John Mompesson, to confident apologetic by Glanvill, before they were further affected by the emergence of articulate scepticism about the case
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