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1. Cognitive Equalization for HF Channels

   N. Teku, T. Bose (January 2018, International Telemetering Conference)
2. Dissociation energy of the HCN⋯HF dimer

   https://doi.org/10.1016/j.cplett.2020.137382  

   Sexton, Thomas More; Van Benschoten, William Zeller; Tschumper, Gregory S. (June 2020, Chemical Physics Letters)
3. A bordered HF^- algebra for the torus

   https://doi.org/10.4310/JSG.250403021401  

   Lipshitz, Robert; Ozsváth, Peter; Thurston, Dylan P (January 2025, Journal of Symplectic Geometry)

   Auroux, Denis; Biran, Paul; Donaldson, Simon; Mrowka, Tomasz (Ed.)

   We describe a weighted A-infinity algebra associated to the torus. We give a combinatorial construction of this algebra, and an abstract characterization. The abstract characterization also gives a relationship between our algebra and the wrapped Fukaya category of the torus. These algebras underpin the (unspecialized) bordered Heegaard Floer homology for three-manifolds with torus boundary, which will be constructed in forthcoming work. 

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4. Fully cognitive transceiver for High Frequency (HF) applications

   https://doi.org/10.1117/12.2515407  

   Teku, Noel H.; Asadi, Hamed; Bose, Tamal; Marefat, Michael (April 2019, SPIE)

   Ionospheric conditions are variable in nature and can cause destructive interference to transmissions made in the High Frequency (HF) band, which ranges from 3-30 MHz. This poses a problem as the HF band is a critical fre- quency range for various applications (i.e. emergency, military). To manage these dynamic conditions, intelligent techniques should be implemented at the transmitter and receiver to properly maintain reliable communications. In this paper, we present work deriving components of a cognitive HF transceiver with agents called cognitive engines (CEs) operating at the transmitter and receiver. At the transmitter, cognition is employed to determine the combination of modulation and coding techniques that maximize throughput. At the receiver, cognition is implemented to derive the best parameters for equalization (i.e. tap length, step size, filter type, etc.) Results are presented showing that the individual components are able to satisfy their objectives. A discussion is also provided surveying recent research efforts pertaining to the development of cognitive methods for the Automatic Link Establishment (ALE) protocol, a common networking methodology for HF stations. 

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5. Bistatic Observations With SuperDARN HF Radars: First Results

   https://doi.org/10.1029/2020RS007121  

   Shepherd, S. G.; Sterne, K. T.; Thomas, E. G.; Ruohoniemi, J. M.; Baker, J. B. H.; Parris, R. T.; Pedersen, T. R.; Holmes, J. M. (August 2020, Radio Science)

   Abstract Super Dual Auroral Radar Network (SuperDARN) radars operate in a coordinated but monostatic configuration whereby high‐frequency (HF) signals scattered from ionospheric density irregularities or from the surface of the Earth return to the transmitting radar where Doppler parameters are then acquired. A bistatic arrangement has been developed for SuperDARN radars in which HF signals transmitted from one radar are received and analyzed by another radar that is separated by a large distance (>1,000 km). This new capability was developed and tested on radars located in Oregon and Kansas. Numerous 3‐day bistatic campaigns have been conducted over a period extending from September 2019 through March 2020. During these campaigns three distinct bistatic propagation modes have been identified including a direct mode in which signals are transmitted and received through the radar side lobes. Direct mode signals propagate along the great‐circle arc connecting the two bistatic radar sites, reflecting from the ionosphere at bothEregion andFregion altitudes. Two additional modes are observed in which HF signals transmitted from one radar scatter from either ionospheric density irregularities or from the surface of the Earth before propagating to the bistatic receiving radar. Ray tracing simulations performed for examples of each mode show good agreement with observations and confirm our understanding of these three bistatic propagation modes. Bistatic campaigns continue to be scheduled in order to improve technical aspects of this new capability, to further explore the physical processes involved in the propagation and scattering of HF bistatic signals and to expand the coverage of ionospheric effects that is possible with SuperDARN. 

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