Results 11 to 20 of about 92,637,410 (303)

Marine mammal conservation: over the horizon

Endangered Species Research, 2021
Marine mammals can play important ecological roles in aquatic ecosystems, and their presence can be key to community structure and function. Consequently, marine mammals are often considered indicators of ecosystem health and flagship species.
SE Nelms, J Alfaro-Shigueto, JPY Arnould, IC Avila, S Bengtson Nash, E Campbell, MID Carter, T Collins, RJC Currey, C Domit, V Franco-Trecu, MMPB Fuentes, E Gilman, RG Harcourt, EM Hines, AR Hoelzel, SK Hooker, DW Johnston, N Kelkar, JJ Kiszka, KL Laidre, JC Mangel, H Marsh, SM Maxwell, AB Onoufriou, DM Palacios, GJ Pierce, LS Ponnampalam, LJ Porter, DJF Russell, KA Stockin, D Sutaria, N Wambiji, CR Weir, B Wilson, BJ Godley   +35 more
doaj   +1 more source

Phased Feature Extraction Network for Vehicle Search Tasks Based on Cross-Camera for Vehicle–Road Collaborative Perception

Sensors, 2023
The objective of vehicle search is to locate and identify vehicles in uncropped, real-world images, which is the combination of two tasks: vehicle detection and re-identification (Re-ID).
Hai Wang, Yaqing Niu, Long Chen, Yicheng Li, Tong Luo   +4 more
doaj   +1 more source

Long-term over-the-horizon microwave channel measurements and statistical analysis in evaporation ducts over the Yellow Sea

Frontiers in Marine Science, 2023
Maritime high-speed over-the-horizon wireless communication is realizable through evaporation ducts. Detailed measurement, analysis, and modeling of duct channels are essential for application of this communication technique.
Shuwen Wang, Shuwen Wang, Shuwen Wang, Kunde Yang, Kunde Yang, Kunde Yang, Yang Shi, Yang Shi, Hao Zhang, Hao Zhang, Fan Yang, Fan Yang, Fan Yang, Dawei Hu, Dawei Hu, Dawei Hu, Guoyu Dong, Guoyu Dong, Guoyu Dong, Yihang Shu, Yihang Shu, Yihang Shu   +21 more
doaj   +1 more source

Utö Observatory for Analysing Atmospheric Ducting Events over Baltic Coastal and Marine Waters

Remote Sensing, 2023
Maritime safety relies on navigation, detection, and radio communication technologies that function through electromagnetic radiation. Propagation of electromagnetic radiation can be impacted by a disruptive phenomenon known as ducting.
Laura Rautiainen, Jani Tyynelä, Mikko Lensu, Simo Siiriä, Ville Vakkari, Ewan O’Connor, Karoliina Hämäläinen, Harry Lonka, Ken Stenbäck, Jarmo Koistinen, Lauri Laakso   +10 more
doaj   +1 more source

A solution for the over-the-horizon-radar simulator [PDF]

Vojnotehnički Glasnik, 2020
Introduction/purpose: The OTHR simulator presented in this paper is developed and used in practice, with the aim of emulating radar signal environment, but also optimizing the radar parameters in real applications such as: radiated power, antenna ...
Bojan R. Džolić, Mladen Đ. Veinović, Vladimir D. Orlić, Nikola L. Lekić, Nemanja R. Grbić   +4 more
doaj   +1 more source

Seasonal Variation in Land and Sea Surface Backscatter Coefficients at High Frequencies

Remote Sensing, 2022
Over the horizon radars (OTHR) rely on the propagation of high frequency (HF) radio waves via the ionosphere to successfully achieve their designated missions.
Danielle Edwards, Manuel Cervera
doaj   +1 more source

First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole [PDF]

, 2019
We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using ...
Sasada, Mahito, The Event Horizon Telescope Collaboration   +1 more
core   +2 more sources

Testing RFoF Link for Transmitting HF-OTHR Signal Between Transmitter and Receiver Shelters

Telfor Journal, 2021
HF-OTHR site contains two equipment shelters, up to 1 km away from each other, that need to be connected for transmitting a FMCW signal. This connection, if realized using a coaxial cable, has shown itself to be vulnerable to external electromagnetic ...
P. Petrović, B. Džolić, N. Lekić, N. Grbić, A. Ćupurdija, V. Orlić, M. Erić   +6 more
doaj   +1 more source

Target Altitude Estimation in Over-the-Horizon Radar

IEEE Access, 2022
Doppler signatures of local multipath signals provide useful information for target altitude estimation in over-the-horizon radar surveillance. In this paper, we develop a method to improve the resolution of these multipath Doppler signatures and enable ...
Yimin D. Zhang, Ammar Ahmed, Braham Himed   +2 more
doaj   +1 more source

Reference source‐aided coordinate registration method for over‐the‐horizon radar using ensemble learning

IET Radar, Sonar & Navigation, 2023
Since solving the path of radio wave propagation by an analytic method in the process of coordinate registration (CR) for skywave over‐the‐horizon radar (OTHR) is difficult, a reference source‐aided CR method that uses ensemble learning is proposed ...
Zhenshuo Lei, Jianwen Chen, Hui Chen, Zhaojian Zhang, Gaoqi Dou, Yongliang Wang   +5 more
doaj   +1 more source