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49 results on '"Cornford, S. L."'

3. Requirements based system level risk modeling

Author

Meshkat, L, Cornford, S. L, and Feather, M. S

Abstract

The problem that we address in this paper is assessing the expected degree of success of the system or mission based on the degree to which each requirement is satisfied and the relative weight of the requirements.

Published
2004

5. Probabilistic risk reduction

Author

Feather, M. S, Cornford, S. L, Meshkat, L, and Kiper, J. D

Subjects
Computer Programming And Software
Abstract

We present an integrated approach to risk assessment and risk mitigation that is well suited to planning the development of complex software systems.

Published
2003

10. Descoping

Author

Feather, M. S, Cornford, S. L, and Hicks, K. A

Subjects
Computer Programming And Software
Published
2002

12. A quantitative risk model for early lifecycle decision making

Author

Feather, M. S, Cornford, S. L, Dunphy, J, and Hicks, K

Abstract

Decisions made in the earliest phases of system development have the most leverage to influence the success of the entire development effort, and yet must be made when information is incomplete and uncertain. We have developed a scalable cost-benefit model to support this critical phase of early-lifecycle decision-making.

Published
2002

14. Cost-benefit based assurance planning

Author

Feather, M. S, Cornford, S. L, and Dunphy, J

Subjects
Computer Programming And Software
Abstract

We have extended an existing risk management framework with a refined cost-benefit model. Benefits are measured in terms of reduction of risk.

Published
2001

15. Incorporating cost-benefit analyses into software assurance planning

Author

Feather, M. S, Sigal, B, Cornford, S. L, and Hutchinson, P

Subjects
Computer Programming And Software
Abstract

The objective is to use cost-benefit analyses to identify, for a given project, optimal sets of software assurance activities. Towards this end we have incorporated cost-benefit calculations into a risk management framework.

Published
2001

16. DDP - a tool for life-cycle risk management

Author

Cornford, S. L, Feather, M. S, and Hicks, K. A

Abstract

At JPL we have developed, and implemented, a process for achieving life-cycle risk management. This process has been embodied in a software tool and is called Defect Detection and Prevention (DDP). The DDP process can be succinctly stated as: determine where we want to be, what could get in the way and how we will get there.

Published
2001

22. Advanced Failure Determination Measurement Techniques Used in Thermal Fatigue Life Testing of Electronic Packaging

Author

Wallace, A. P, Cornford, S. L, and Gross, M. A

Subjects
Electronics And Electrical Engineering
Abstract

Thermal fatigue life testing of various electronic packaging technologies is being performed by the Reliability Technology Group at the Jet Propulsion Laboratory. These testing efforts are in progress to improve uderstanding of the reliability issues associated with low volume packaging technologies for space applications and to develop qualification and acceptance approaches for these technologies. The work described here outlines the electrical failure detection techniques used during testing by documenting the circuits and components used to make these measurements, the sensitivity of the measurements, and the applicability of each specific measurement.

Published
1996

24. Dynamic control of visible radiation by a liquid crystal filled Fabry-Pérot etalon.

Author

Jewell, S. A., Cornford, S. L., and Sambles, J. R.

Subjects
*LIQUID crystals, *ELECTROMAGNETIC waves, *DIELECTRIC devices, *OPTICS, *ELECTRIC fields
Abstract

A liquid crystal filled Fabry-Pérot etalon has been constructed to control the resonant transmission of electromagnetic radiation over the visible range of the spectrum. This has been achieved through the use of a 1.5 μm thick homogeneously aligned liquid crystal layer in the core of a silver-clad etalon structure. Applying an electric field across the core reorientates the liquid crystal director and changes the refractive index for incident light polarized parallel to the rubbing direction. By measuring the transmitted intensity as a function of wavelength for a variety of applied voltages shifts in the positions of the resonant transmission modes of up to 80 nm have been observed. In addition, these results have been compared to model data generated using a multilayer optics model to obtain the dispersion of the liquid crystal over the visible range of the electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

Published
2007
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26. Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate

Author

Cornford, S. L., Martin, D. F., Payne, A. J., Ng, E. G., Le Brocq, A. M., Gladstone, R. M., Edwards, T. L., Shannon, S. R., Agosta, C., van den Broeke, M. R., Hellmer, H. H., Krinner, G., Ligtenberg, S. R. M., Timmermann, R., Vaughan, D. G., Sub Dynamics Meteorology, Marine and Atmospheric Research, University of Bristol [Bristol], Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK., Université de Liège, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institute for Marine and Atmospheric Research [Utrecht] (IMAU), Utrecht University [Utrecht], Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), School of Geographical Sciences, University of Bristol, Bristol, United Kingdom, Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Lawrence Berkeley National Laboratory [Berkeley] ( LBNL ), University of Liege Belgium, Laboratoire de glaciologie et géophysique de l'environnement ( LGGE ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ), Institute for Marine and Atmospheric Research Utrecht ( IMAU ), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung ( AWI ), Institute for Marine and Atmospheric Research Utrecht, British Antarctic Survey ( BAS ), Natural Environment Research Council ( NERC ), Sub Dynamics Meteorology, and Marine and Atmospheric Research

Subjects
SHELF, 010504 meteorology & atmospheric sciences, SURFACE MASS-BALANCE, Ice stream, FLOW, MODELS, Antarctic ice sheet, Antarctic sea ice, 010502 geochemistry & geophysics, 01 natural sciences, Ice shelf, [ SDE ] Environmental Sciences, Sea ice, Cryosphere, Ice divide, BED, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, lcsh:GE1-350, geography, geography.geographical_feature_category, lcsh:QE1-996.5, WEDDELL SEA SECTOR, RETREAT, lcsh:Geology, GROUNDING-LINE MIGRATION, 13. Climate action, Climatology, [SDE]Environmental Sciences, PINE ISLAND GLACIER, Ice sheet, SENSITIVITY, Geology
Abstract

We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet. Each of the simulations begins with a geometry and velocity close to present day observations, and evolves according to variation in meteoric ice accumulation, ice shelf melting, and mesh resolution. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rates anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions, ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Sensitivity to mesh resolution is spurious, and we find that sub-kilometer resolution is needed along most regions of the grounding line to avoid systematic under-estimates of the retreat rate, although resolution requirements are more stringent in some regions – for example the Amundsen Sea Embayment – than others – such as the Möller and Institute ice streams.

Published
2015

28. Supplementary material to "Experimental design for three interrelated Marine Ice-Sheet and Ocean Model Intercomparison Projects"

Author

Asay-Davis, X. S., primary, Cornford, S. L., additional, Durand, G., additional, Galton-Fenzi, B. K., additional, Gladstone, R. M., additional, Gudmundsson, G. H., additional, Hattermann, T., additional, Holland, D. M., additional, Holland, D., additional, Holland, P. R., additional, Martin, D. F., additional, Mathiot, P., additional, Pattyn, F., additional, and Seroussi, H., additional

Published
2015
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29. Experimental design for three interrelated Marine Ice-Sheet and Ocean Model Intercomparison Projects

Author

Asay-Davis, X. S., primary, Cornford, S. L., additional, Durand, G., additional, Galton-Fenzi, B. K., additional, Gladstone, R. M., additional, Gudmundsson, G. H., additional, Hattermann, T., additional, Holland, D. M., additional, Holland, D., additional, Holland, P. R., additional, Martin, D. F., additional, Mathiot, P., additional, Pattyn, F., additional, and Seroussi, H., additional

Published
2015
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30. Supplementary material to "Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate"

Author

Cornford, S. L., primary, Martin, D. F., additional, Payne, A. J., additional, Ng, E. G., additional, Le Brocq, A. M., additional, Gladstone, R. M., additional, Edwards, T. L., additional, Shannon, S. R., additional, Agosta, C., additional, van den Broeke, M. R., additional, Hellmer, H. H., additional, Krinner, G., additional, Ligtenberg, S. R. M., additional, Timmermann, R., additional, and Vaughan, D. G., additional

Published
2015
Full Text
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31. Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate

Author

Cornford, S. L., primary, Martin, D. F., additional, Payne, A. J., additional, Ng, E. G., additional, Le Brocq, A. M., additional, Gladstone, R. M., additional, Edwards, T. L., additional, Shannon, S. R., additional, Agosta, C., additional, van den Broeke, M. R., additional, Hellmer, H. H., additional, Krinner, G., additional, Ligtenberg, S. R. M., additional, Timmermann, R., additional, and Vaughan, D. G., additional

Published
2015
Full Text
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33. Relating risk and reliability predictions to design and development choices

Author

Feather, M. S. and Cornford, S. L.

Abstract

Ideally, planning and managing the design and development of complex systems should: 1) consider the entire lifecycle (design, development, testing, integration, deployment, operation and decommissioning). 2) Take risk and reliability into account, as well as more traditional measures such as cost and performance, when making tradeoff decisions. A key enabler to all of the above is the ability to relate design and development choices to risk and reliability predictions. The challenge is that in many cases the number of design and development alternatives is large. In this context, the problem of relating reliability predictions to design and development choices is non-trivial. Over several years we have developed a risk-based model the hallmark of which is the explicit representation of risk mitigations as options. We describe how this model functions, and the major implications of making mitigation options first class objects within an (otherwise relatively simple) analysis model. We also describe elaborations to this model's representation of risks, notably by the incorporation of fault tree notions. These improve the fidelity of the designs we are able to represent, and also offer the ability to represent design alternatives within the same framework. Finally, we describe the connections we are building between our risk analysis tool and other risk tools

Published
2006

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