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1. New Zealand’s Gas Hydrate Systems

Author

Mienert, J., Berndt, Christian, Tréhu, A. M., Camerlenghi, A., Liu, C. S., Pecher, I., Crutchley, Gareth, Kröger, K. F., Hillman, Jess, Mountjoy, J., Coffin, R., Gorman, A., Mienert, J., Berndt, Christian, Tréhu, A. M., Camerlenghi, A., Liu, C. S., Pecher, I., Crutchley, Gareth, Kröger, K. F., Hillman, Jess, Mountjoy, J., Coffin, R., and Gorman, A.

Abstract

New Zealand’s large offshore region is dominated by the collision of the Pacific and Australian Plates. Gas hydrates have been identified in three areas: the Hikurangi Margin, the Taranaki and Northland Basins, and the Fiordland-Puysegur Margin. The Hikurangi Margin subduction margin to the east of the North Island stands out, displaying numerous indications of highly-concentrated gas hydrate occurrences. This subduction zone constitutes an environment with high fluid flow and rapidly changing pressure–temperature conditions, leading to anomalies such as the occurrence of double-bottom simulating reflections (BSRs). The Taranaki and Northland Basins west of the North Island is New Zealand’s most prominent petroleum province. So far, however, only limited evidence for hydrate occurrence has been found there. BSRs have also been detected south of the South Island along the Fiordland-Puysegur Margin, an incipient subduction zone. It is likely that gas hydrates are present elsewhere along New Zealand’s vast continental margins.

Published
2022
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2. Motivational Influences on Computer-Related Affective States.

Author

Coffin, R. J. and MacIntyre, P. D.

Abstract

This study of college students examined the effects of motivation to learn to use computers, and previous experience with computers, on three computer-related affective states: anxiety, attitudes, and self-efficacy. Discusses gender differences, path analysis, effects on academic performance, and intrinsic versus extrinsic reasons for taking the course. Contains 60 references. (Author/LRW)

Published
1999

23. Predicting Noise From Aircraft Turbine-Engine Combustors

Author

Gliebe, P, Mani, R, Salamah, S, Coffin, R, and Mehta, Jayesh

Subjects
Aircraft Propulsion And Power
Abstract

COMBUSTOR and CNOISE are computer codes that predict far-field noise that originates in the combustors of modern aircraft turbine engines -- especially modern, low-gaseous-emission engines, the combustors of which sometimes generate several decibels more noise than do the combustors of older turbine engines. COMBUSTOR implements an empirical model of combustor noise derived from correlations between engine-noise data and operational and geometric parameters, and was developed from databases of measurements of acoustic emissions of engines. CNOISE implements an analytical and computational model of the propagation of combustor temperature fluctuations (hot spots) through downstream turbine stages. Such hot spots are known to give rise to far-field noise. CNOISE is expected to be helpful in determining why low-emission combustors are sometimes noisier than older ones, to provide guidance for refining the empirical correlation model embodied in the COMBUSTOR code, and to provide insight on how to vary downstream turbinestage geometry to reduce the contribution of hot spots to far-field noise.

Published
2005

28. Critical Propulsion and Noise reduction Technologies for Future Commercial Subsonic Engines. Area of Interest 14.3: Separate Flow Exhaust System Noise

Author

Janardan, B. A, Hoff, G. E, Barter, J. W, Brausch, J. F, Gliebe, P. R, Coffin, R. S, Martens, S, Delaney, B. R, Dalton, W. N, and Mengle, V. G

Subjects
Acoustics
Abstract

This presentation discusses: Project Objectives, Approach and Goal; Baseline Nozzles and Test Cycle Definition; Repeatability and Baseline Nozzle Results; Noise Reduction Concepts; Noise Reduction Tests Configurations of BPR=5 Internal Plug Nozzle adn Acoustic Results; Noise Reduction Test Configurations of BPR=5 External Plug Nozzle and Acoustic Results; and Noise Reduction Tests Configurations of BPR=8 External Plug Nozzle and Acoustic Results.

Published
2000

32. Discovery Planetary Mission Operations Concepts

Author

Coffin, R

Subjects
Lunar And Planetary Science And Exploration
Abstract

The NASA Discovery Program of small planetary missions will provide opportunities to continue scientific exploration of the solar system in today's cost-constrained environment. Using a multidisciplinary team, JPL has developed plans to provide mission operations within the financial parameters established by the Discovery Program. This paper describes experiences and methods that show promise of allowing the Discovery Missions to operate within the program cost constraints while maintaining low mission risk, high data quality, and reponsive operations.

Published
1994

41. CHRIMP - Chatham Rise (Methane) Pockmarks

Author

Bialas, Jörg, Sarkar, Sudipta, Klaucke, Ingo, Pecher, I., Waghorn, K., Hoffmann, Jasper, Schneider von Deimling, Jens, Dannowski, Anke, Erogluer, Nur, Eckardt, Thomas, Davy, B., Coffin, R., Rose, P., Papenberg, Cord, and Koch, Stephanie

Published
2015

43. The Fate of Bubbles in a Large, Intense Bubble Megaplume for Stratified and Unstratified Water : Numerical Simulations of 22/4b Expedition Field Data

Author

Leifer, I., Solomon, E., Schneider von Deimling, Jens, Rehder, Gregor, Coffin, R., Linke, Peter, Leifer, I., Solomon, E., Schneider von Deimling, Jens, Rehder, Gregor, Coffin, R., and Linke, Peter

Abstract

Extremely intense bubble plumes, like the North Sea 22/4b blowout megaplume (defined as more than 10(6) L day(-1)), create very strong upwelling flows (>1 m s(-1)), which lead to detrainment of methane-enriched water, but leave direct bubble-mediated transport unaffected. Dissolved CH4 depth profiles and atmospheric measurements during a fall 2011 survey of the 22/4b site suggest strong constraint of seabed CH4 below the thermocline. Seabed bubbles were nearly pure CH4. The effect of the upwelling flow on the fate of bubble plume CH4 was investigated with a numerical bubble-propagation model. The model considered different representative bubble plume size distributions, phi, and a global (total) megaplume bubble size distribution, Phi, synthesized from video survey data and phi from the literature. Simulations showed that none of the literature plumes or variations in the upwelling flow could constrain CH4 sufficiently below the thermocline. Two new bubble megaplume processes were simulated, vortical bubble trapping (slow rise) and a hypothesized, enhanced bubble gas exchange, k(BE), an enhancement factor applied to the normal bubble gas exchange rate, k(B). The latter could arise from plume turbulence increasing bubble boundary-layer turbulence and thus its gas exchange. Observations could not be reproduced solely by slow rise, however, simulations with k(BE)similar to 6 reproduced observational constraints, as could weaker k(BE) in conjunction with slow rise. Field validation of k(BE) is needed given its implications for the fate of megaplume CH4 emissions (anthropogenic or natural) for stratified and unstratified conditions. kBE suggests marine CH4 geologic contributions to the atmosphere from all but shallow waters primarily arises from bubble plumes that are less than megaplume size.

Published
2015
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