8,856 research outputs found
NO sub x deposited in the stratosphere by the space shuttle, phase 1
The results of calculations to determine the amount of NOx deposited in the stratosphere by space shuttle solid rocket motors (SRM) are presented. Flow properties and chemical composition in the exhaust nozzle and plume were analyzed. The nozzle calculations show that about 4.5 lbm/sec of NOx leaves the two SRMs. The total amount of NOx deposited in the stratosphere is related to the amount leaving the nozzle via an overall plume enhancement factor (OPEF), which depends upon the influence of afterburning and shocks in enhancing the exit plane NOx mole fraction. Calculations show that the OPEF is approximately 2, indicating the mass flow of NOx in the plume to be approximately l0 lbm/sec at 30 km altitude with a possible error factor of 4. For a vehicle velocity of 3750 ft/sec, therefore, the NOx deposition rate in the stratosphere is about 2.7 x 10(-3) lbm/ft
Model metadata report for a 3D model of Black Down, Mendips
This report is the published metadata details of a 3d modelling study by the British Geological
Survey (BGS), and is based on the eastern section of the Mendips called Black Down. The
model was developed under the 3d Models for Teaching team, part of the Geological Modelling
Systems program at BGS. 3D geological models have great potential as a resource for
universities when teaching foundation geological concepts as it allows the student to visualise
and interrogate UK geology. They are especially useful when dealing with the conversion of 2D
field, map and GIS outputs into three dimensional geological units, which is a common problem
for all students of geology. Today’s earth science students use a variety of skills and processes
during their learning experience including the application of schema’s, spatial thinking, image
construction, detecting patterns, memorising figures, mental manipulation and interpretation,
making predictions and deducing the orientation of themselves and the rocks. 3D geological
models can reinforce spatial thinking strategies and encourage students to think about processes
and properties, in turn helping the student to recognise pre-learnt geological principles in the
field and to convert what they see at the surface into a picture of what is going on at depth
Metadata report for the Knowsley 3D geological model
This report describes the metadata generated during the creation of a 3D geological model for the
Environment Agency (EA) in the Knowsley area in NW England. Knowsley Industrial Park,
NW England and its buried sewerage network presents a potential source of pollution to the
underlying Triassic Sherwood Sandstone Group aquifer. Weakly permeable superficial deposits
beneath the site may provide a barrier to potential pollution of groundwater in the aquifer. The
aim of the study was to develop and apply a 3D model of the superficial deposits beneath the
park to a qualitative assessment of the vulnerability of the underlying aquifer to potential
pollution. The study also aimed to devise a method for the integration of the 3D geological
model of the shallow sub-surface with the buried utility network.
The 3D model revealed 7 superficial units. Glacial till, comprising clay and silt, was the only
weakly permeable deposit identified. Other deposits were interpreted as permeable. The
underground utility network was integrated in 3D with the geological model. Those utilities
overlying less than 2.5 m of till were interpreted to represent the most vulnerable parts of the
underlying aquifer. The greatest relative vulnerability to the aquifer occurred in the south and
south-west of the project area.
The study identified a novel method for the integration of a 3D geological model and a buried
sewerage network. The identification of these utilities prioritised the areas of highest relative
vulnerability of the Sherwood Sandstone aquifer to potential pollution from utility leakage. This
approach enabled the development of a hazard identification and prioritisation scheme for future
improvements to the buried sewerage network serving Knowsley Industrial Park
Computational models for the viscous/inviscid analysis of jet aircraft exhaust plumes
Computational models which analyze viscous/inviscid flow processes in jet aircraft exhaust plumes are discussed. These models are component parts of an NASA-LaRC method for the prediction of nozzle afterbody drag. Inviscid/shock processes are analyzed by the SCIPAC code which is a compact version of a generalized shock capturing, inviscid plume code (SCIPPY). The SCIPAC code analyzes underexpanded jet exhaust gas mixtures with a self-contained thermodynamic package for hydrocarbon exhaust products and air. A detailed and automated treatment of the embedded subsonic zones behind Mach discs is provided in this analysis. Mixing processes along the plume interface are analyzed by two upgraded versions of an overlaid, turbulent mixing code (BOAT) developed previously for calculating nearfield jet entrainment. The BOATAC program is a frozen chemistry version of BOAT containing the aircraft thermodynamic package as SCIPAC; BOATAB is an afterburning version with a self-contained aircraft (hydrocarbon/air) finite-rate chemistry package. The coupling of viscous and inviscid flow processes is achieved by an overlaid procedure with interactive effects accounted for by a displacement thickness type correction to the inviscid plume interface
Magnetic properties of microtektites Semiannual status report, 1 Jan. - 31 Jun. 1969
Magnetic susceptibility, magnetization, and Curie constants for normal and bottle-green microtektites found in deep-sea sediment core
NO sub X Deposited in the Stratosphere by the Space Shuttle Solid Rocket Motors
The possible effects of the interaction of the plumes from the two solid rocket motors (SRM) from the space shuttles and mixing of the rocket exhaust products and ambient air in the base recirculation region on the total nitrous oxide deposition rate in the stratosphere were investigated. It was shown that these phenomena will not influence the total NOx deposition rate. It was also shown that uncertainties in the particle size of Al2O3, size distributions and particle/gas drag and heat transfer coefficients will not have a significant effect on the predicted NOx deposition rate. The final results show that the total mass flow of NOx leaving the plume at 30 km altitude is 4000 g./sec with a possible error factor of 3. For a vehicle velocity of 1140 meter/sec this yields an NOx deposition rate of about 3.5 g./meter. The corresponding HCl deposition rate at this altitude is about a factor of 500 greater than this value
Algorithms for 3D rigidity analysis and a first order percolation transition
A fast computer algorithm, the pebble game, has been used successfully to
study rigidity percolation on 2D elastic networks, as well as on a special
class of 3D networks, the bond-bending networks. Application of the pebble game
approach to general 3D networks has been hindered by the fact that the
underlying mathematical theory is, strictly speaking, invalid in this case. We
construct an approximate pebble game algorithm for general 3D networks, as well
as a slower but exact algorithm, the relaxation algorithm, that we use for
testing the new pebble game. Based on the results of these tests and additional
considerations, we argue that in the particular case of randomly diluted
central-force networks on BCC and FCC lattices, the pebble game is essentially
exact. Using the pebble game, we observe an extremely sharp jump in the largest
rigid cluster size in bond-diluted central-force networks in 3D, with the
percolating cluster appearing and taking up most of the network after a single
bond addition. This strongly suggests a first order rigidity percolation
transition, which is in contrast to the second order transitions found
previously for the 2D central-force and 3D bond-bending networks. While a first
order rigidity transition has been observed for Bethe lattices and networks
with ``chemical order'', this is the first time it has been seen for a regular
randomly diluted network. In the case of site dilution, the transition is also
first order for BCC, but results for FCC suggest a second order transition.
Even in bond-diluted lattices, while the transition appears massively first
order in the order parameter (the percolating cluster size), it is continuous
in the elastic moduli. This, and the apparent non-universality, make this phase
transition highly unusual.Comment: 28 pages, 19 figure
- …