11,507 research outputs found
Synthesis and analysis of jet fuels from shale oil and coal syncrudes
The technical problems involved in converting a significant portion of a barrel of either a shale oil or coal syncrude into a suitable aviation turbine fuel were studied. TOSCO shale oil, H-Coal and COED coal syncrudes were the starting materials. They were processed by distillation and hydrocracking to produce two levels of yield (20 and 40 weight percent) of material having a distillation range of approximately 422 to 561 K (300 F to 550 F). The full distillation range 311 to 616 K (100 F to 650 F) materials were hydrotreated to meet two sets of specifications (20 and 40 volume percent aromatics, 13.5 and 12.75 weight percent H, 0.2 and 0.5 weight percent S, and 0.1 and 0.2 weight percent N). The hydrotreated materials were distilled to meet given end point and volatility requirements. The syntheses were carried out in laboratory and pilot plant equipment scaled to produce thirty-two 0.0757 cu m (2-gal)samples of jet fuel of varying defined specifications. Detailed analyses for physical and chemical properties were made on the crude starting materials and on the products
Spin gating electrical current
We use an aluminium single electron transistor with a magnetic gate to
directly quantify the chemical potential anisotropy of GaMnAs materials.
Uniaxial and cubic contributions to the chemical potential anisotropy are
determined from field rotation experiments. In performing magnetic field sweeps
we observe additional isotropic magnetic field dependence of the chemical
potential which shows a non-monotonic behavior. The observed effects are
explained by calculations based on the kinetic
exchange model of ferromagnetism in GaMnAs. Our device inverts the conventional
approach for constructing spin transistors: instead of spin-transport
controlled by ordinary gates we spin-gate ordinary charge transport.Comment: 5 pages, 4 figure
Spectral properties of a Rydberg atom immersed in a Bose-Einstein condensate
The electronic spectrum of a Rydberg atom immersed in a Bose-Einstein
condensate is investigated. The Heisenberg equations of motions for the
condensate and the Rydberg atom are derived. Neglecting the backaction of the
Rydberg atom onto the condensate decouples the equations describing the
condensate and Rydberg atom. In this case the spectral structure of the Rydberg
atom is completely determined by an effective potential which depends on the
density distribution of the condensate. We study the spectral properties for
the situation of an isotropic harmonic and anharmonic as well as axially
symmetric confinement. In the latter case an intriguing analogy with Rydberg
atoms in magnetic fields is encountered
Dust in the wind: Crystalline silicates, corundum and periclase in PG 2112+059
We have determined the mineralogical composition of dust in the Broad
Absorption Line (BAL) quasar PG 2112+059 using mid-infrared spectroscopy
obtained with the Spitzer Space Telescope. From spectral fitting of the solid
state features, we find evidence for Mg-rich amorphous silicates with olivine
stoichiometry, as well as the first detection of corundum (Al_2O_3) and
periclase (MgO) in quasars. This mixed composition provides the first direct
evidence for a clumpy density structure of the grain forming region. The
silicates in total encompass 56.5% of the identified dust mass, while corundum
takes up 38 wt.%. Depending on the choice of continuum, a range of mass
fractions is observed for periclase ranging from 2.7% in the most conservative
case to 9% in a less constrained continuum. In addition, we identify a feature
at 11.2 micron as the crystalline silicate forsterite, with only a minor
contribution from polycyclic aromatic hydrocarbons. The 5% crystalline silicate
fraction requires high temperatures such as those found in the immediate quasar
environment in order to counteract rapid destruction from cosmic rays.Comment: 2 figure
Analysis and Implementation of Median Type Filters
Median filters are a special class of ranked order filters used for smoothing signals. These filters have achieved- success in speech processing, image processing, and other impulsive noise environments where linear filters have proven inadequate. Although the implementation of a median filter requires only a simple digital operation, its properties are not easily analyzed. Even so, a number of properties have been exhibited in the literature. In this thesis, a new tool, known as threshold decomposition is introduced for the analysis and implementation of median type filters. This decomposition of multi-level signals into sets of binary signals has led to significant theoretical and practical breakthroughs in the area of median filters. A preliminary discussion on using the threshold decomposition as an algorithm for a fast and parallel VLSI Circuit implementation of ranked filters is also presented* In addition, the theory is developed both for determining the number of signals which are invariant to arbitrary window width median filters when any number of quantization levels are allowed and for counting or estimating the number of passes required to produce a root- i.e. invariant signal, for binary signals. Finally, the analog median filter is defined and proposed for analysis of the standard discrete median filter in cases with a large sample size or when the associated statistics would be simpler in the continuu
On network modeling of manufacturing and related processes using GERT Summary report
Network modeling of manufacturing and related processes using Graphical Evaluation and Review Techniqu
- …