3,943 research outputs found
Self-regulating proportionally controlled heating apparatus and technique
A self-regulating proportionally controlled heating apparatus and technique is provided wherein a single electrical resistance heating element having a temperature coefficient of resistance serves simultaneously as a heater and temperature sensor. The heating element is current-driven and the voltage drop across the heating element is monitored and a component extracted which is attributable to a change in actual temperature of the heating element from a desired reference temperature, so as to produce a resulting error signal. The error signal is utilized to control the level of the heater drive current and the actual heater temperature in a direction to reduce the noted temperature difference. The continuous nature of the process for deriving the error signal feedback information results in true proportional control of the heating element without the necessity for current-switching which may interfere with nearby sensitive circuits, and with no cyclical variation in the controlled temperature
Implementation of a self-controlling heater: A concept
Proposed heater uses its own temperature coefficient for sensing function. Heating power is supplied from current source, heater voltage containing temperature information. Dynamic stability is very high since there is no thermal lag as would exist with separate heater and sensor
Position sensing device employing misaligned magnetic field generating and detecting apparatus Patent
Magnetic element position sensing device, using misaligned electromagnet
Cloud absorption radiometer
The Cloud Absorption Radiometer (CAR) was developed to measure spectrally how light is scattered by clouds and to determine the single scattering albedo, important to meteorology and climate studies, with unprecedented accuracy. This measurement is based on ratios of downwelling to upwelling radiation within clouds, and so is not strongly dependent upon absolute radiometric calibration of the instrument. The CAR has a 5-inch aperture and 1 degree IFOV, and spatially scans in a plane orthogonal to the flight vector from the zenith to nadir at 1.7 revolutions per second. Incoming light is measured in 13 spectral bands, using silicon, germanium, and indium-antimonide detectors. Data from each channel is digitally recorded in flight with 10-bit (0.1 percent) resolution. The instrument incorporates several novel features. These features are briefly detailed
Towards quantitative accuracy in first-principles transport calculations: The GW method applied to alkane/gold junctions
The calculation of electronic conductance of nano-scale junctions from first
principles is a long standing problem in molecular electronics. Here we
demonstrate excellent agreement with experiments for the transport properties
of the gold/alkanediamine benchmark system when electron-electron interactions
are described using the many-body GW approximation. The main difference from
standard density functional theory (DFT) calculations is a significant
reduction of the contact conductance, G_c, due an improved alignment of the
molecular energy levels with the metal Fermi energy. The molecular orbitals
involved in the tunneling process comprise states delocalized over the carbon
backbone and states localized on the amine end groups. We find that dynamical
screening effects renormalize the two types of states in qualitatively
different ways when the molecule is inserted in the junction. Consequently, the
GW transport results cannot be mimicked by DFT calculations employing a simple
scissors operator.Comment: 7 page
Image-charge induced localization of molecular orbitals at metal-molecule interfaces: Self-consistent GW calculations
Quasiparticle (QP) wave functions, also known as Dyson orbitals, extend the
concept of single-particle states to interacting electron systems. Here we
employ many-body perturbation theory in the GW approximation to calculate the
QP wave functions for a semi-empirical model describing a -conjugated
molecular wire in contact with a metal surface. We find that image charge
effects pull the frontier molecular orbitals toward the metal surface while
orbitals with higher or lower energy are pushed away. This affects both the
size of the energetic image charge shifts and the coupling of the individual
orbitals to the metal substrate. Full diagonalization of the QP equation and,
to some extent, self-consistency in the GW self-energy, is important to
describe the effect which is not captured by standard density functional theory
or Hartree-Fock. These results should be important for the understanding and
theoretical modeling of electron transport across metal-molecule interfaces.Comment: 7 pages, 6 figure
Pottery Making Possibilities of The Clays of Ellis County, Kansas
The north half of Ellis County from Big Greek to the Saline River has numerous deposits of clay, while the south half of the county has few outcroppings . From Big Creek to the Smoky Hill River on the south, any clay there may be is covered by a rich top soil which has filled the lowlands from the hills north of Hays, to the low hills along the river. There are numerous deposits of shale in the hills south of the Saline which could be used commercially for tile or brick manufacture, however, their dark color lessens their value as a body for the making of art pottery. A few light firing clays were found, but without exception, their high content of sand, and subsequent high porosity, make their successful use doubtful
Turbine blade and vane heat flux sensor development, phase 2
The development of heat flux sensors for gas turbine blades and vanes and the demonstration of heat transfer measurement methods are reported. The performance of the heat flux sensors was evaluated in a cylinder in cross flow experiment and compared with two other heat flux measurement methods, the slug calorimeter and a dynamic method based on fluctuating gas and surface temperature. Two cylinders, each instrumented with an embedded thermocouple sensor, a Gardon gauge, and a slug calorimeter, were fabricated. Each sensor type was calibrated using a quartz lamp bank facility. The instrumented cylinders were then tested in an atmospheric pressure combustor rig at conditions up to gas stream temperatures of 1700K and velocities to Mach 0.74. The test data are compared to other measurements and analytical prediction
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