7,904 research outputs found
Context Trees: Augmenting Geospatial Trajectories with Context
Exposing latent knowledge in geospatial trajectories has the potential to
provide a better understanding of the movements of individuals and groups.
Motivated by such a desire, this work presents the context tree, a new
hierarchical data structure that summarises the context behind user actions in
a single model. We propose a method for context tree construction that augments
geospatial trajectories with land usage data to identify such contexts. Through
evaluation of the construction method and analysis of the properties of
generated context trees, we demonstrate the foundation for understanding and
modelling behaviour afforded. Summarising user contexts into a single data
structure gives easy access to information that would otherwise remain latent,
providing the basis for better understanding and predicting the actions and
behaviours of individuals and groups. Finally, we also present a method for
pruning context trees, for use in applications where it is desirable to reduce
the size of the tree while retaining useful information
Trip Prediction by Leveraging Trip Histories from Neighboring Users
We propose a novel approach for trip prediction by analyzing user's trip
histories. We augment users' (self-) trip histories by adding 'similar' trips
from other users, which could be informative and useful for predicting future
trips for a given user. This also helps to cope with noisy or sparse trip
histories, where the self-history by itself does not provide a reliable
prediction of future trips. We show empirical evidence that by enriching the
users' trip histories with additional trips, one can improve the prediction
error by 15%-40%, evaluated on multiple subsets of the Nancy2012 dataset. This
real-world dataset is collected from public transportation ticket validations
in the city of Nancy, France. Our prediction tool is a central component of a
trip simulator system designed to analyze the functionality of public
transportation in the city of Nancy
Report of the In Situ Resources Utilization Workshop
The results of a workshop of 50 representatives from the public and private sector which investigated the potential joint development of the key technologies and mechanisms that will enable the permanent habitation of space are presented. The workshop is an initial step to develop a joint public/private assessment of new technology requirements of future space options, to share knowledge on required technologies that may exist in the private sector, and to investigate potential joint technology development opportunities. The majority of the material was produced in 5 working groups: (1) Construction, Assembly, Automation and Robotics; (2) Prospecting, Mining, and Surface Transportation; (3) Biosystems and Life Support; (4) Materials Processing; and (5) Innovative Ventures. In addition to the results of the working groups, preliminary technology development recommendations to assist in near-term development priority decisions are presented. Finally, steps are outlined for potential new future activities and relationships among the public, private, and academic sectors
Agglomeration Elasticities in New Zealand
This paper analyses the relationship between firms’ multi-factor productivity and the effective employment density of the areas where they operate. Quantifying these agglomeration elasticities is of central importance in the evaluation of the wider economic benefits of transport investments. We estimate agglomeration elasticities using the Statistics New Zealand prototype Longitudinal Business Database: a firm-level panel covering the period 1999 to 2006. We estimate that an area with 10 percent higher effective density has firms with productivity that is 0.69 percent higher, once we control for the industry specific production functions and sorting of more productive firms across industries and locations. We present separate estimates of agglomeration elasticities for specific industries and regions, and examine the interaction of agglomeration with capital, labour, and other inputs.Agglomeration, urban density, transport evaluation, productivity
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