8,187 research outputs found
Very high voltage latching relay
Relay consists of high voltage reed switch actuated by rotating permanent magnet mounted on stepper motor shaft, with actuation assembly isolated from high voltage circuit. Unit can be modified for use as double pole or double pole double throw latching relay and can be used in either air or vacuum
Process for preparing liquid metal electrical contact device
The parts of an electrical contact device are treated by sputter etching to remove the parent metal oxide. Prior to exposure of the electrodes to any oxygen, a sacrificial metal is sputter deposited on the parts. Preferably this sacrificial metal is one that oxidizes slowly and is readily dissolved by the liquid metal. The sacrificial metal may then be removed from unwanted areas. The remainder of the ring and the probe to be wet by the liquid metal are submerged in the liquid metal or the liquid metal is flushed over these areas, preferably while they are being slightly abraded, unitl all the sacrificial material on these portions is wet by the liquid metal. In doing so the liquid metal dissolves the sacrificial metal and permanently wets the parent metal. Preferred materials used in the process and for the electrodes of electrical contact devices are high purity (99.0%) nickel or AISI type 304 stainless steel for the electrical contact devices, gallium as the liquid metal, and gold as the sacrificial material
Liquid Level Sensor for High Temperature Molten Salt in Confined Container
Electrical resistance measurements on different rod materials in liquid solutions, molten salts, or molten lead are considered to design a liquid level sensor in a sealed containers when the temperature of the fluid is very high (~1000ºC) and conventional measurements are not possible due to properties of the fluid or condition of the container. An analytical solution to the problem is adopted to reduce the cost of the sensor and overcome the difficulties of calibration of sensors at high temperature for prediction of the level of liquid. An electrical circuit model is suggested for analytical solution to compute the resistivity versus height of the electrode rod submerged in the liquid in a narrow container. Good prediction of circuit model for experimental results is verified by comparison of analytical results of different combination of liquid solutions and rods’ material with experimental graphs
Titanium honeycomb structure
A brazed titanium honeycomb sandwich system for supersonic transport wing cover panels provides the most efficient structure spanwise, chordwise, and loadwise. Flutter testing shows that high wing stiffness is most efficient in a sandwich structure. This structure also provides good thermal insulation if liquid fuel is carried in direct contact with the wing structure in integral fuel tanks
Orientation to the sun by animals and its interaction with crypsis
1. Orientation with respect to the sun has been observed in a wide range of species and hasgenerally been interpreted in terms of thermoregulation and/or ultraviolet (UV) protection. For countershaded animals, orientation with respect to the sun may also result from the pres-sure to exploit the gradient of coloration optimally to enhance crypsis.2. Here, we use computational modelling to predict the optimal countershading pattern for anoriented body. We assess how camouflage performance declines as orientation varies using acomputational model that incorporates realistic lighting environments.3. Once an optimal countershading pattern for crypsis has been chosen, we determineseparately how UV protection/irradiation and solar thermal inflow fluctuate with orientation.4. We show that body orientations that could optimally use countershading to enhance crypsisare very similar to those that allow optimal solar heat inflow and UV protection.5. Our findings suggest that crypsis has been overlooked as a selective pressure on orientationand that new experiments should be designed to tease apart the respective roles of these different selective pressures. We propose potential experiments that could achieve this
Evaluating leadership's approach to implementing organizational change across the Naval Aviation Enterprise with a focus on the development of Fleet Readiness Centers
MBA Professional ReportNAVAIR is currently realigning its Aviation Maintenance infrastructure to fall under the overarching umbrella of the newly minted Naval Aviation Enterprise (NAE). This realignment will call for a new enterprise-wide strategy and structure. Hierarchies and relationships are being redefined throughout the enterprise resulting in entirely new organizational structures functionally equivalent to industryb2ss small business units. This realignment will result in the elimination of Intermediate level maintenance as it exists today and presents a myriad of challenges to the Fleet in the terms of achieving business efficiencies and employee relationship management. This MBA Project evaluates, by survey, how effectively the U. S. Navy and Marine Corps have managed the change effort as they continue to realign their Intermediate and Depot level units under the new FRC construct.http://archive.org/details/evaluatingleader1094510097US Navy (USN) authorApproved for public release; distribution is unlimited
Inferring Gene Family Histories in Yeast Identifies Lineage Specific Expansions
PublishedThe complement of genes found in the genome is a balance between gene gain and gene loss. Knowledge of the specific genes that are gained and lost over evolutionary time allows an understanding of the evolution of biological functions. Here we use new evolutionary models to infer gene family histories across complete yeast genomes; these models allow us to estimate the relative genome-wide rates of gene birth, death, innovation and extinction (loss of an entire family) for the first time. We show that the rates of gene family evolution vary both between gene families and between species. We are also able to identify those families that have experienced rapid lineage specific expansion/contraction and show that these families are enriched for specific functions. Moreover, we find that families with specific functions are repeatedly expanded in multiple species, suggesting the presence of common adaptations and that these family expansions/contractions are not random. Additionally, we identify potential specialisations, unique to specific species, in the functions of lineage specific expanded families. These results suggest that an important mechanism in the evolution of genome content is the presence of lineage-specific gene family changes.This work is funded by BBSRC grant BB/I020489/1. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Dual-Frequency Observations of 140 Compact, Flat-Spectrum Active Galactic Nuclei for Scintillation-Induced Variability
The 4.9 GHz Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey
detected a drop in Interstellar Scintillation (ISS) for sources at redshifts z
> 2, indicating an apparent increase in angular diameter or a decrease in flux
density of the most compact components of these sources, relative to their
extended emission. This can result from intrinsic source size effects or
scatter broadening in the Intergalactic Medium (IGM), in excess of the expected
(1+z)^0.5 angular diameter scaling of brightness temperature limited sources
due to cosmological expansion. We report here 4.9 GHz and 8.4 GHz observations
and data analysis for a sample of 140 compact, flat-spectrum sources which may
allow us to determine the origin of this angular diameter-redshift relation by
exploiting their different wavelength dependences. In addition to using ISS as
a cosmological probe, the observations provide additional insight into source
morphologies and the characteristics of ISS. As in the MASIV Survey, the
variability of the sources is found to be significantly correlated with
line-of-sight H-alpha intensities, confirming its link with ISS. For 25
sources, time delays of about 0.15 to 3 days are observed between the
scintillation patterns at both frequencies, interpreted as being caused by a
shift in core positions when probed at different optical depths. Significant
correlation is found between ISS amplitudes and source spectral index; in
particular, a large drop in ISS amplitudes is observed at spectral indices of <
-0.4 confirming that steep spectrum sources scintillate less. We detect a
weakened redshift dependence of ISS at 8.4 GHz over that at 4.9 GHz, with the
mean variance at 4-day timescales reduced by a factor of 1.8 in the z > 2
sources relative to the z < 2 sources, as opposed to the factor of 3 decrease
observed at 4.9 GHz. This suggests scatter broadening in the IGM.Comment: 30 pages, 14 figures, accepted for publication in the Astronomical
Journa
General Purpose Real-Time Object Tracking using Hausdorff Transforms
We describe a real-time computer-vision tracking module capable of using several Hausdorff distance based approaches to localize and match edge models in a scene. The implementation is based on widely supported software and hardware technologies such as Microsoft DirectX/DirectShow, Intel Image Processing and the Open Source Computer Vision libraries
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