In natural and urban canyon environments, Global Navigation Satellite System (GNSS) signals suffer from various challenges such as signal multipath, limited or lack of signal availability and poor geometry. Inertial sensors are often employed to improve the solution continuity under poor GNSS signal quality and availability conditions. Various fault detection schemes have been proposed in the literature to detect and remove biased GNSS measurements to obtain a more reliable navigation solution. However, many of these methods are found to be sub-optimal and often lead to unavailability of reliability measures, mostly because of the improper characterization of the measurement errors. A robust filtering architecture is thus proposed which assumes a heavy-tailed distribution for the measurement errors. Moreover, the proposed filter is capable of adapting to the changing GNSS signal conditions such as when moving from open sky conditions to deep canyons. Results obtained by processing data collected in various GNSS challenged environments show that the proposed scheme provides a robust navigation solution without having to excessively reject usable measurements. The tests reported herein show improvements of nearly 15% and 80% for position accuracy and reliability, respectively, when applying the above approach.
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Sci Rep
January 2025
Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316, Oslo, Norway.
In the subauroral zone at the boundary of the auroral oval in the evening and night hours during geomagnetic disturbances, a narrow (about 1°-2°) and extended structure (several hours in longitude) is formed. It is known as a polarization jet (PJ) or the subauroral ion drift (SAID). The PJ/SAID is a fast westward ion drift and is one of the main signatures of a geomagnetic disturbance in the subauroral ionosphere at the altitudes of the F-layer, when the geomagnetic AE index reaches more than 500 nT.
View Article and Find Full Text PDFJ Colloid Interface Sci
January 2025
The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Frontiers Science Center of Biomimetic Catalysis, and Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234 China. Electronic address:
A gold-cerium bimetallic asteroid nanoplatform (CeO@GNSs/Myr-HA) was obtained by electrostatically adsorbing ultra-small cerium dioxide (CeO) onto gold nanostars (GNSs) and further loading myricetin (Myr) and hyaluronic acid (HA). This nanoplatform exhibited three types of enzymatic properties-that is, GOD (glucose-oxidase), POD (peroxidase) and GSH-Ox (glutathione oxidase) mimicking catalytic activities. These enzymatic properties work together to effectively induce apoptosis in tumor cells.
View Article and Find Full Text PDFSensors (Basel)
January 2025
China Railway Construction Bridge Engineering Bureau Group Co., Ltd., Tianjin 300300, China.
GNSS-RTK offers numerous advantages and broad prospects in structural dynamic monitoring in civil engineering. However, in practical applications, GNSS-RTK accuracy is susceptible to the monitoring environments, causing actual monitoring accuracy to fall below its calibrated accuracy. This study investigates the monitoring accuracy and spectral characteristics of GNSS-RTK based on stability tests under different environments related to reflection and obstruction conditions (i.
View Article and Find Full Text PDFSci Rep
January 2025
Key Laboratory of Poyang Lake Wetland and Watershed Research Ministry of Education, Jiangxi Normal University, Nanchang, 330022, China.
Surface loading effects related to atmospheric, hydrological, non-tidal ocean, are one of the principal sources of the seasonal oscillations in GNSS time series, and it should be taken into account for improving GNSS accuracy. In this study, the daily vertical time series of 9 GNSS stations at Hong Kong was used to investigate the surface loading (sum of atmospheric loading, hydrological loading, non-tidal ocean loading (AHNL)) contributors of seasonal oscillations in GNSS observations. This paper reveals a correlation between the AHNL deformation and the GNSS vertical time series, with an average correlation coefficient of 0.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Laboratory of Intelligent Control, Rocket Force University of Engineering, Xi'an 710025, China.
Experts and scholars from various nations have proposed studying low Earth orbit (LEO) satellite signals as the space-based signals of opportunity (SOPs) for navigation and positioning. This method serves as a robust alternative in environments where global navigation satellite systems (GNSS) are unavailable or compromised, providing users with high-precision, anti-interference, secure, and dependable backup navigation solutions. The rapid evolution of LEO communication constellations has spurred the development of SOPs positioning technology using LEO satellites.
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