3,245 research outputs found
A Map-matching Algorithm with Extraction of Multi-group Information for Low-frequency Data
The growing use of probe vehicles generates a huge number of GNSS data.
Limited by the satellite positioning technology, further improving the accuracy
of map-matching is challenging work, especially for low-frequency trajectories.
When matching a trajectory, the ego vehicle's spatial-temporal information of
the present trip is the most useful with the least amount of data. In addition,
there are a large amount of other data, e.g., other vehicles' state and past
prediction results, but it is hard to extract useful information for matching
maps and inferring paths. Most map-matching studies only used the ego vehicle's
data and ignored other vehicles' data. Based on it, this paper designs a new
map-matching method to make full use of "Big data". We first sort all data into
four groups according to their spatial and temporal distance from the present
matching probe which allows us to sort for their usefulness. Then we design
three different methods to extract valuable information (scores) from them: a
score for speed and bearing, a score for historical usage, and a score for
traffic state using the spectral graph Markov neutral network. Finally, we use
a modified top-K shortest-path method to search the candidate paths within an
ellipse region and then use the fused score to infer the path (projected
location). We test the proposed method against baseline algorithms using a
real-world dataset in China. The results show that all scoring methods can
enhance map-matching accuracy. Furthermore, our method outperforms the others,
especially when GNSS probing frequency is less than 0.01 Hz.Comment: 10 pages, 11 figures, 4 table
Cryopreservation of Orchid Genetic Resources by Desiccation: A Case Study of Bletilla formosana
Many native orchid populations declined yearly due to economic development and climate change. This resulted in some wild orchids being threatened. In order to maintain the orchid genetic resources, development of proper methods for the longâterm preservation is urgent. Low temperature or dry storage methods for the preservation of orchid genetic resources have been implemented but are not effective in maintaining high viability of certain orchids for long periods. Cryopreservation is one of the most acceptable methods for longâterm conservation of plant germplasm. Orchid seeds and pollens are ideal materials for longâterm preservation (seed banking) in liquid nitrogen (LN) as the seeds and pollens are minute, enabling the storage of many hundreds of thousands of seeds or pollens in a small vial, and as most species germinate readily, making the technique very economical. This article describes cryopreservation of orchid genetic resources by desiccation and a case study of Bletilla formosana. We hope to provide a more practical potential cryopreservation method for future research needs
Experimental study on the heat transfer characteristics of a low melting point salt in a parabolic trough solar collector system
MicroRNA-132 promotes estradiol synthesis in ovarian granulosa cells via translational repression of Nurr1
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