9,668 research outputs found
Canadian ERTS program progress report
Progress of the Canadian ERTS program is provided along with statistics on the production and role of ERTS images both from the CCRS in Ottawa and from the Prince Albert Saskatchewan satellite station. The types of products, difficulties of production and some of the main applications in Canada are discussed
The use of GIS in Brownfield redevelopment
In recent years, the issue of Brownfield site development - the re-use of previously used urban land - has gained a significant place in the planning agenda. However, not all Brownfield sites are derelict or contaminated land, some are significant as environmental amenities - be it part of wider ecosystem or a green area for the local population. The growing concern to include environmental aspects into the public debate have lead the Environment Agency, the Jackson Environment Institute and the Centre for Advanced Spatial Analysis to commission a short term pilot study to evaluate the contribution of a GIS for decision support and for "discussion support".In this paper, we describe how the state-of-the-art in geographic information (GI) and GI Science (GISc) can be used in a short term and limited project to achieve a practical and usable system. We are drawing on developments in information availability, as made accessible through the World Wide Web and research themes in GISc ranging from Multimedia GIS to Public Participation GIS
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A numerical model of the ionospheric signatures of time-varying magnetic reconnection: III. Quasi-instantaneous convection responses in the Cowley-Lockwood paradigm
Using a numerical implementation of the Cowley and Lockwood (1992) model of flow excitation in the magnetosphere–ionosphere (MI) system, we show that both an expanding (on a _12-min timescale) and a quasiinstantaneous response in ionospheric convection to the onset of magnetopause reconnection can be accommodated by the Cowley–Lockwood conceptual framework. This model has a key feature of time dependence, necessarily considering the history of the coupled MI system. We show that a residual flow, driven by prior magnetopause reconnection, can produce a quasi-instantaneous global ionospheric convection response; perturbations from an equilibrium state may also be present from tail reconnection, which will superpose constructively to give a similar effect. On the other hand, when the MI system is relatively free of pre-existing flow, we can most clearly see the expanding nature of the response. As the open-closed field line boundary will frequently be in motion from such prior reconnection (both at the dayside magnetopause and in the cross-tail current sheet), it is expected that there will usually be some level of combined response to dayside reconnection
Quantitative assessment of Earth’s radiation belt modeling
The “Quantitative Assessment of Radiation Belt Modeling” focus group was in place at Geospace Environment Modeling from 2014 to 2018. The overarching goals of this focus group were to bring together the current state‐of‐the‐art models for the acceleration, transport, and loss processes in Earth's radiation belts; develop event‐specific and global inputs of wave, plasma, and magnetic field to drive these models; and combine all these components to achieve a quantitative assessment of radiation belt modeling by validating against contemporary radiation belt measurements. This article briefly reviews the current understanding of radiation belt dynamics and related modeling efforts, summarizes the activities and accomplishments of the focus group, and discusses future directions.Accepted manuscrip
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A numerical model of the ionospheric signatures of time-varying magnetic reconnection: II. Measuring expansions in the ionospheric flow response
A numerical model embodying the concepts of the Cowley-Lockwood (Cowley and Lockwood, 1992, 1997) paradigm has been used to produce a simple Cowley– Lockwood type expanding flow pattern and to calculate the resulting change in ion temperature. Cross-correlation, fixed threshold analysis and threshold relative to peak are used to determine the phase speed of the change in convection pattern, in response to a change in applied reconnection. Each of these methods fails to fully recover the expansion of the onset of the convection response that is inherent in the simulations. The results of this study indicate that any expansion of the convection pattern will be best observed in time-series data using a threshold which is a fixed fraction of the peak response. We show that these methods used to determine the expansion velocity can be used to discriminate between the two main models for the convection response to a change in reconnection
Quantitative assessment of radiation belt modeling
The “Quantitative Assessment of Radiation Belt Modeling” focus group was in place at Geospace Environment Modeling from 2014 to 2018. The overarching goals of this focus group were to bring together the current state‐of‐the‐art models for the acceleration, transport, and loss processes in Earth's radiation belts; develop event‐specific and global inputs of wave, plasma, and magnetic field to drive these models; and combine all these components to achieve a quantitative assessment of radiation belt modeling by validating against contemporary radiation belt measurements. This article briefly reviews the current understanding of radiation belt dynamics and related modeling efforts, summarizes the activities and accomplishments of the focus group, and discusses future directions.Accepted manuscrip
Two-phase flow in a porous medium modeling
This research is devoted to the multiphase modeling in substances containing pores. The experimental setup is built in Comsol Multiphysics package and constitutes a soil column that deals with two substances when one of them goes from above of the column while the other one goes from below. Throughout the experiment air represents the 'upper' substance while the second one varies. The varying matter allows checking the model for its accuracy. After the check the transition to the air/oil system is done. The result of simulation is distribution of substance pressure in the laboratory column at the final time
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