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991.
Open source, spatial analysis, and activity-travel behaviour research: capabilities of the aspace package 总被引：2，自引：0，他引：2
This paper reports on recent experience with the development of aspace, an Open Source (OS) library for the geographic visualization and analysis of activity-travel behaviour. The paper begins
with an overview of recent progress with respect to the convergence of Open Source technology, spatial analysis, and travel
behaviour research. The remainder of the paper focuses on aspace; a collection of functions that, when combined with data describing the geographical location of daily activities, can be
used to visualize and describe spatial properties of individual and household activity spaces. These properties include: size,
orientation, shape, and the geographical dispersion of activity locations contained within the activity space. Several planar
geometries are used to transform measurable spatial properties into intuitive objects for visualizing spatial patterns of
activity participation. Experiments are conducted, using data from the first wave of the 2003 Toronto Travel Activity Panel
Survey, to demonstrate the potential application of aspace for basic and applied policy-based research into activity-travel behaviour. The toolkit is distributed as a downloadable
‘package’ from the Open Source R Project for Statistical Computing.
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The history of the discovery of hot gas in galaxies is briefly reviewed, and the main properties of this gas described, emphasizing the need to refine these properties, in particular, the mass of the gas. It is proposed to do this via observations of the Sunyaev-Zel’dovich (SZ) effect due to hot gas in the coronas of elliptical galaxies. The absolute and relative perturbations of the spectrum of the cosmic microwave background (CMB) radiation due to scattering of the CMB photons by electrons with a Maxwellian energy distribution are calculated. The possibility of observing the SZ effect is demonstrated using three elliptical galaxies as examples. The kinematic SZ effect arising due to the peculiar motions and rotations of the galaxies is also accessible to observations. Together with X-ray data, such observations would enable refinement of the properties of gas in galaxies, and also yield additional information about the rotation of galaxies, possible accretion flows in the galactic gas, and hot galactic winds. 相似文献