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2,600 results on '"Orr J"'

401. 4.3.0 Panel 4.3.0: Discovering a Strategy for Whole Systems Modeling

Author

Ring, J., primary, Bahill, T., additional, Blackmon, T., additional, Cloutier, R., additional, Clymer, J., additional, Hodgson, R., additional, Jacoby, C., additional, Krane, S., additional, Lloyd, K., additional, Newman, R. A., additional, Orr, J., additional, Rose, C., additional, Skipper, J., additional, Sorenson, R., additional, and Steiner, R., additional

Published
2007
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408. Composite bulkhead fabrication development

Author

Orr, J

Subjects
Mechanics
Abstract

Composite bulkhead is produced by a fabrication concept utilizing vacuum and/or autoclave pressure to hold preformed welded sandwich elements in place during bonding and aging.

Published
1966

409. Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment.

Author

Séférian, R., Gehlen, M., Bopp, L., Resplandy, L., Orr, J. C., Marti, O., Dunne, J. P., Christian, J. R., Doney, S. C., Ilyina, T., Lindsay, K., Halloran, P., Heinze, C., Segschneider, J., and Tjiputra, J.

Subjects
OCEAN, BIOGEOCHEMICAL cycles, EARTH system science
Abstract

During the fifth phase of the Coupled Model Intercomparison Project (CMIP5) substantial efforts were carried out on the systematic assessment of the skill of Earth system models. One goal was to check how realistically representative marine biogeochemical tracer distributions could be reproduced by models. Mean-state assessments routinely compared model hindcasts to available modern biogeochemical observations. However, these assessments considered neither the extent of equilibrium in modeled biogeochemical reservoirs nor the sensitivity of model performance to initial conditions or to the spin-up protocols. Here, we explore how the large diversity in spin-up protocols used for marine biogeochemistry in CMIP5 Earth system models (ESM) contribute to model-to-model differences in the simulated fields. We take advantage of a 500 year spin-up simulation of IPSL-CM5A-LR to quantify the influence of the spin-up protocol on model ability to reproduce relevant data fields. Amplification of biases in selected biogeochemical fields (O2, NO3, Alk-DIC) is assessed as a function of spin-up duration. We demonstrate that a relationship between spin-up duration and assessment metrics emerges from our model results and is consistent when confronted against a larger ensemble of CMIP5 models. This shows that drift has implications on their performance assessment in addition to possibly aliasing estimates of climate change impact. Our study suggests that differences in spin-up protocols could explain a substantial part of model disparities, constituting a source of model-to-model uncertainty. This requires more attention in future model intercomparison exercices in order to provide realistic ESM results on marine biogeochemistry and carbon cycle feedbacks. [ABSTRACT FROM AUTHOR]

Published
2015
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410. Individual differences in regional prefrontal gray matter morphometry and fractional anisotropy are associated with different constructs of executive function.

Author

Smolker, H., Depue, B., Reineberg, A., Orr, J., and Banich, M.

Subjects
INDIVIDUAL differences, PREFRONTAL cortex, ANISOTROPY, BRAIN function localization, VOXEL-based morphometry, NEURONS
Abstract

Although the relationship between structural differences within the prefrontal cortex (PFC) and executive function (EF) has been widely explored in cognitively impaired populations, little is known about this relationship in healthy young adults. Using optimized voxel-based morphometry (VBM), surface-based morphometry (SBM), and fractional anisotropy (FA) we determined the association between regional PFC grey matter (GM) morphometry and white matter tract diffusivity with performance on tasks that tap different aspects of EF as drawn from Miyake et al.'s three-factor model of EF. Reductions in both GM volume (VBM) and cortical folding (SBM) in the ventromedial PFC (vmPFC), ventrolateral PFC (vlPFC), and dorsolateral PFC (dlPFC) predicted better common EF, shifting-specific, and updating-specific performance, respectively. Despite capturing different components of GM morphometry, voxel- and surface-based findings were highly related, exhibiting regionally overlapping relationships with EF. Increased white matter FA in fiber tracts that connect the vmPFC and vlPFC with posterior regions of the brain also predicted better common EF and shifting-specific performance, respectively. These results suggest that the neural mechanisms supporting distinct aspects of EF may differentially rely on distinct regions of the PFC, and at least in healthy young adults, are influenced by regional morphometry of the PFC and the FA of major white matter tracts that connect the PFC with posterior cortical and subcortical regions. [ABSTRACT FROM AUTHOR]

Published
2015
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411. Evaluation of a parallel implementation of the learning portion of the backward error propagation neural network: experiments in artifact identification

Author

Sittig, D. F. and Orr, J. A.

Subjects
Evaluation Studies as Topic, Software Design, Learning, Neural Networks, Computer, Artifacts, Algorithms, Research Article
Abstract

Various methods have been proposed in an attempt to solve problems in artifact and/or alarm identification including expert systems, statistical signal processing techniques, and artificial neural networks (ANN). ANNs consist of a large number of simple processing units connected by weighted links. To develop truly robust ANNs, investigators are required to train their networks on huge training data sets, requiring enormous computing power. We implemented a parallel version of the backward error propagation neural network training algorithm in the widely portable parallel programming language C-Linda. A maximum speedup of 4.06 was obtained with six processors. This speedup represents a reduction in total run-time from approximately 6.4 hours to 1.5 hours. We conclude that use of the master-worker model of parallel computation is an excellent method for obtaining speedups in the backward error propagation neural network training algorithm.

Published
1991

422. European research

Author

Orr, J Stewart

Subjects
Correspondence
Published
1990

437. Evaluating global ocean carbon models: The importance of realistic physics

Author

Doney, S. C., primary, Lindsay, K., additional, Caldeira, K., additional, Campin, J.-M., additional, Drange, H., additional, Dutay, J.-C., additional, Follows, M., additional, Gao, Y., additional, Gnanadesikan, A., additional, Gruber, N., additional, Ishida, A., additional, Joos, F., additional, Madec, G., additional, Maier-Reimer, E., additional, Marshall, J. C., additional, Matear, R. J., additional, Monfray, P., additional, Mouchet, A., additional, Najjar, R., additional, Orr, J. C., additional, Plattner, G.-K., additional, Sarmiento, J., additional, Schlitzer, R., additional, Slater, R., additional, Totterdell, I. J., additional, Weirig, M.-F., additional, Yamanaka, Y., additional, and Yool, A., additional

Published
2004
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443. Evaluation of ocean carbon cycle models with data‐based metrics

Author

Matsumoto, K., primary, Sarmiento, J. L., additional, Key, R. M., additional, Aumont, O., additional, Bullister, J. L., additional, Caldeira, K., additional, Campin, J.‐M., additional, Doney, S. C., additional, Drange, H., additional, Dutay, J.‐C., additional, Follows, M., additional, Gao, Y., additional, Gnanadesikan, A., additional, Gruber, N., additional, Ishida, A., additional, Joos, F., additional, Lindsay, K., additional, Maier‐Reimer, E., additional, Marshall, J. C., additional, Matear, R. J., additional, Monfray, P., additional, Mouchet, A., additional, Najjar, R., additional, Plattner, G.‐K., additional, Schlitzer, R., additional, Slater, R., additional, Swathi, P. S., additional, Totterdell, I. J., additional, Weirig, M.‐F., additional, Yamanaka, Y., additional, Yool, A., additional, and Orr, J. C., additional

Published
2004
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450. Model-Based 3-D Object Identification.

Author

WORCESTER POLYTECHNIC INST MA, Cyganski, David, Vaz, R. F., Orr, J. A., WORCESTER POLYTECHNIC INST MA, Cyganski, David, Vaz, R. F., and Orr, J. A.

Abstract

The ATR technique developed in this project is based on a new non-linear pose estimator rather than on search mechanisms. Low false alarm rate performance is obtained by not forming a pose invariant detector but instead by incorporating pose dependent object information within the recognition process. The ATR is factored into a computationally intensive preparation process and a fast on-line target identification process. The approach is model-based and free of assumptions about the imaging process and object characteristics, and, can be applied to ATR and the estimation of pose parameters for articulated or multi-configuration targets from image and non-image sensor data. In this work, the initial concept of the pose estimator for 1 DOF (degree-of-freedom) problems was developed into a system for N DOF whole and partially obscured target pose indexing and recognition. Performance was demonstrated at the level of filter bank implementations for 1 DOF problems at 1/17 the computational cost for unobscured targets and false alarm rates orders of magnitude better than that of the filter bank approach for obscured targets. The computational savings further increase with N for N DOF problems. The report contains ROC curves obtained from tests using the public MSTAR data set.

Published
1998

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