In this paper, we describe an air temperature movement by mapping its time series to the polar coordinates: the value of the
time series is plotted on the radial coordinate and the time on the angular coordinate. In this way, both the yearly and daily
air temperature movements from five different locations of China are used to demonstrate that, in an intuitionistic view,
air temperature movement is neither random nor chaotic, but has its own orbit. We then propose an elliptic orbit model for
the air temperature movement. Our proposed model provides quite good results when it is applied to the evaluation of yearly
air temperature movements in eight locations in various parts of the world, and the evaluation of daily air temperature movements
in five locations in Hunan Province of China on December 17, 2005. Results show that our approach provides a concise and helpful
model for air temperature analysis. 相似文献
Scholars of environmental injustice have pushed to see beyond the spatial distribution of environmental harms in studies of unwanted land uses. Building upon this work, this article examines how the complex geographies of environmental injustice play out in a coalition to prevent the construction of a coal-fired power plant in Surry County, Virginia. While spatially dispersed coalitions of negatively affected actors can strengthen efforts to prevent the construction of an unwanted land use, they can also perpetuate the environmental injustices surrounding it. To make this argument, particular attention is paid to the diverse reasons and ways differentially situated actors oppose an unwanted land use. It is demonstrated how the disparate concerns and differential tactics deployed by actors in coalitions against unwanted land uses are often embedded in and potentially contribute to longer histories of social injustice. 相似文献
Objective: Intersection movement assist (IMA) has been recognized as one of the prominent countermeasures to reduce angle crashes at intersections, which constitute 22% of total crashes in the United States. Utilizing vehicle-based sensors, vehicle-to-vehicle (V2V), and vehicle-to-infrastructure (V2I) communications, IMA offers extended vision to provide early warning for an imminent crash. However, most of IMA-related research implements their methods and strategies only in simulations, test tracks, or driving simulator studies that have quite a few assumptions and limitations and hence the effectiveness evaluations reported may not be transferable or comparable.
Methods: This study seeks to develop a generalized evaluation scheme that can be used not only to assess the effectiveness of IMA on improving traffic safety at intersections but to facilitate comparisons across similar studies. The proposed evaluation scheme utilizes the concepts of traffic conflict in terms of time-to-collision (TTC) as a crash surrogate. This approach avoids the issue of having insufficient crash frequency data for system evaluation. To measure the effectiveness of IMA on reducing traffic conflicts, a relative risk is calculated for comparing the risk of with/without using the IMA. As a proof-of-concept study, this study applied the proposed evaluation scheme and reported the effectiveness of IMA on improving traffic safety in a field operation test (FOT). Seven test scenarios were conducted at 4 intersections, and a total of 40 participants were recruited to use the IMA for 6 months.
Results: It was estimated that IMA users have 26% fewer conflicts with TTC less than 5 s and have 15% fewer conflicts with TTC less than 4 s. However, the results vary across different sites and different definitions of conflicts in terms of TTC.
Conclusions: Overall, IMA is promising to effectively reduce angle crashes related to sight obstruction and has potential to reduce not only crash frequency but crash severity. 相似文献