178,857 research outputs found
Welded repairs of punctured thin-walled aluminum pressure vessels
Punctures in thin-walled aluminum pressure vessels are repaired by plugging the hole with an interference-fit disc and welding the unit. The repaired vessels withstood test pressures in excess of vessel ultimate design values for 2-, 4-, and 6-inch holes in 0.202-inch-thick aluminum alloy parent material
Heavy Rainfall Warning Assessment Tool User Guide. Version 1.2
This report is a User Guide to a PC tool for assessing Heavy Rainfall Warnings. Development of the PC tool formed an important operational output of the Environment Agency and Met Office funded project: "Development of Rainfall Forecast Performance Monitoring Criteria. Phase 1: Development of Methodology and Algorithms" (Jones et al., 2003).
The Heavy Rainfall Warning (HRW) Assessment Tool is a toolkit for Microsoft Excel. The tool allows the user to configure an assessment framework for a particular format of Heavy Rainfall Warning, enter and save data for forecasts and ground-truths, and generate a range of performance measures and other statistics for new and previously saved data. Summary tables are presented using Excel's PivotTable feature, from which charts can also be generated.
Performance measures are provided to assess forecasts of heavy rainfall in continuous variable, categorical and probability form: these include bias, rmse, R-squared Efficiency, skill scores and the Continuous Brier Score
Current practice in the modelling of Age, Period and Cohort effects with panel data: a commentary
This comment assesses how age, period and cohort (APC) effects are modelled with panel data in the social sciences. It considers variations on a 2-level multilevel model which has been used to show apparent evidence for simultaneous APC effects. We show that such an interpretation is often misleading, and that the formulation and interpretation of these models requires a better understanding of APC effects and the exact collinearity present between them. This interpretation must draw on theory to justify the claims that are made. By comparing two papers which over-interpret such a model, and another that in our view interprets it appropriately, we outline best practice for researchers aiming to use panel datasets to find APC effects, with an understanding that it is impossible for any statistical model to find and separate all three effects
Generalization of color by chickens: experimental observations and a Bayesian model
Sensory generalization influences animals' responses to novel stimuli. Because color forms a perceptual continuum, it is a good subject for studying generalization. Moreover, because different causes of variation in spectral signals, such as pigmentation, gloss, and illumination, have differing behavioral significance, it may be beneficial to have adaptable generalization. We report on generalization by poultry chicks following differential training to rewarded (T+) and unrewarded (Tâ) colors, in particular on the phenomenon of peak shift, which leads to subjects preferring stimuli displaced away from Tâ. The first three experiments test effects of learning either a fine or a coarse discrimination. In experiments 1 and 2, peak shift occurs, but contrary to some predictions, the shift is smaller after the animal learned a fine discrimination than after it learned a coarse discrimination. Experiment 3 finds a similar effect for generalization on a color axis orthogonal to that separating T+ from Tâ. Experiment 4 shows that generalization is rapidly modified by experience. These results imply that the scale of a âperceptual rulerâ is set by experience. We show that the observations are consistent with generalization following principles of Bayesian inference, which forms a powerful framework for understanding this type of behavior
TTF: a flexible approach to narrowband imaging
The Taurus Tunable Filter (TTF) is a tunable narrowband interference filter
covering wavelengths from 6300 A to the sensitivity drop-off of conventional
CCDs (9600 A), although a blue `arm' (3700-6500 A) is to be added by the end of
1997. The TTF offers monochromatic imaging at the cassegrain foci of both the
Anglo-Australian and William Herschel Telescopes, with an adjustable passband
of between 6 and 60 A. In addition, frequency switching with the TTF can be
synchronized to movement of charge (charge shuffling) on the CCD which has many
important applications in astrophysics. Here we review different modes of TTF.
We maintain a web site at http://msowww.anu.edu.au/~dhj/ttf.html describing all
aspects of TTF and its operation. In addition to general use, the instrument is
available in AAT service time. Details can be found at
http://www.aao.gov.au/local/www/jmc/service/service.html.Comment: 8 pages; Latex; 5 encapsulated postscript figures. Invited talk at
the "AAO/UKST Galactic Plane H-alpha Survey", International Workshop, Sydney,
Australi
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