34,536 research outputs found
Domestic applications for aerospace waste and water management technologies
Some of the aerospace developments in solid waste disposal and water purification, which are applicable to specific domestic problems are explored. Also provided is an overview of the management techniques used in defining the need, in utilizing the available tools, and in synthesizing a solution. Specifically, several water recovery processes will be compared for domestic applicability. Examples are filtration, distillation, catalytic oxidation, reverse osmosis, and electrodialysis. Solid disposal methods will be discussed, including chemical treatment, drying, incineration, and wet oxidation. The latest developments in reducing household water requirements and some concepts for reusing water will be outlined
The Migration and Growth of Protoplanets in Protostellar Discs
We investigate the gravitational interaction of a Jovian mass protoplanet
with a gaseous disc with aspect ratio and kinematic viscosity expected for the
protoplanetary disc from which it formed. Different disc surface density
distributions have been investigated. We focus on the tidal interaction with
the disc with the consequent gap formation and orbital migration of the
protoplanet. Nonlinear hydrodynamic simulations are employed using three
independent numerical codes.
A principal result is that the direction of the orbital migration is always
inwards and such that the protoplanet reaches the central star in a near
circular orbit after a characteristic viscous time scale of approximately
10,000 initial orbital periods. This was found to be independent of whether the
protoplanet was allowed to accrete mass or not. Inward migration is helped
through the disappearance of the inner disc, and therefore the positive torque
it would exert, because of accretion onto the central star.Our results indicate
that a realistic upper limit for the masses of closely orbiting giant planets
is approximately 5 Jupiter masses, because of the reduced accretion rates
obtained for planets of increasing mass.
Assuming some process such as termination of the inner disc through a
magnetospheric cavity stops the migration, the range of masses estimated for a
number of close orbiting giant planets (Marcy, Cochran, & Mayor 1999; Marcy &
Butler 1998) as well as their inward orbital migration can be accounted for by
consideration of disc--protoplanet interactions during the late stages of giant
planet formation. Maximally accreting protoplanets reached about four Jovian
masses on reaching the neighbourhood of the central star.Comment: 19 pages, 16 figures, submitted to MNRAS. A version of this paper
that includes high resolution figures may be obtained from
http://www.maths.qmw.ac.uk/~rpn/preprint.htm
The 10 to the 8th power bit solid state spacecraft data recorder
The results are summarized of a program to demonstrate the feasibility of Bubble Domain Memory Technology as a mass memory medium for spacecraft applications. The design, fabrication and test of a partially populated 10 to the 8th power Bit Data Recorder using 100 Kbit serial bubble memory chips is described. Design tradeoffs, design approach and performance are discussed. This effort resulted in a 10 to the 8th power bit recorder with a volume of 858.6 cu in and a weight of 47.2 pounds. The recorder is plug reconfigurable, having the capability of operating as one, two or four independent serial channel recorders or as a single sixteen bit byte parallel input recorder. Data rates up to 1.2 Mb/s in a serial mode and 2.4 Mb/s in a parallel mode may be supported. Fabrication and test of the recorder demonstrated the basic feasibility of Bubble Domain Memory technology for such applications. Test results indicate the need for improvement in memory element operating temperature range and detector performance
Interplanetary propulsion using inertial fusion
Inertial fusion can be used to power spacecraft within the solar system and beyond. Such spacecraft have the potential for short-duration manned-mission performance exceeding other technologies. We are conducting a study to assess the systems aspects of inertial fusion as applied to such missions, based on the conceptual engine design of Hyde (1983) we describe the required systems for an entirely new spacecraft design called VISTA that is based on the use of DT fuel. We give preliminary design details for the power conversion and power conditioning systems for manned missions to Mars of total duration of about 100 days. Specific mission performance results will be published elsewhere, after the study has been completed
Velocity fluctuations of noisy reaction fronts propagating into a metastable state: testing theory in stochastic simulations
The position of a reaction front, propagating into a metastable state,
fluctuates because of the shot noise of reactions and diffusion. A recent
theory [B. Meerson, P.V. Sasorov, and Y. Kaplan, Phys. Rev. E 84, 011147
(2011)] gave a closed analytic expression for the front diffusion coefficient
in the weak noise limit. Here we test this theory in stochastic simulations
involving reacting and diffusing particles on a one-dimensional lattice. We
also investigate a small noise-induced systematic shift of the front velocity
compared to the prediction from the spatially continuous deterministic
reaction-diffusion equation.Comment: 5 pages, 5 figure
Ultra-fine beryllium powder by amalgam process Progress report, period ending 31 Oct. 1966
Metallurgical evaluation of beryllium powdered metal, and electron microscope studies of agglomerate particle size
All-optical conditional logic with a nonlinear photonic crystal nanocavity
We demonstrate tunable frequency-converted light mediated by a chi-(2)
nonlinear photonic crystal nanocavity. The wavelength-scale InP-based cavity
supports two closely-spaced localized modes near 1550 nm which are resonantly
excited by a 130 fs laser pulse. The cavity is simultaneously irradiated with a
non-resonant probe beam, giving rise to rich second-order scattering spectra
reflecting nonlinear mixing of the different resonant and non-resonant
components. In particular, we highlight the radiation at the sum frequencies of
the probe beam and the respective cavity modes. This would be a useful,
minimally-invasive monitor of the joint occupancy state of multiple cavities in
an integrated optical circuit.Comment: 4 pages, 4 figure
Analytical and experimental investigation of gas bearing tilting pad pivots Final report
Fretting damage in gas bearing tilting pad pivot
Enhancing single-molecule photostability by optical feedback from quantum-jump detection
We report an optical technique that yields an enhancement of single-molecule
photostability, by greatly suppressing photobleaching pathways which involve
photoexcitation from the triplet state. This is accomplished by dynamically
switching off the excitation laser when a quantum-jump of the molecule to the
triplet state is optically detected. This procedure leads to a lengthened
single-molecule observation time and an increased total number of detected
photons. The resulting improvement in photostability unambiguously confirms the
importance of photoexcitation from the triplet state in photobleaching
dynamics, and may allow the investigation of new phenomena at the
single-molecule level
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