skip to main content


Search for: All records

Award ID contains: 2148178

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Free, publicly-accessible full text available January 1, 2025
  2. Federated learning (FL) is a collaborative machine-learning (ML) framework particularly suited for ML models requiring numerous training samples, such as Convolutional Neural Networks (CNNs), Recurrent Neural Networks (RNNs), and Random Forest, in the context of various applications, e.g., next-word prediction and eHealth. FL involves various clients participating in the training process by uploading their local models to an FL server in each global iteration. The server aggregates these models to update a global model. The traditional FL process may encounter bottlenecks, known as the straggler problem, where slower clients delay the overall training time. This paper introduces the Latency-awarE Semi-synchronous client Selection and mOdel aggregation for federated learNing (LESSON) method. LESSON allows clients to participate at different frequencies: faster clients contribute more frequently, therefore mitigating the straggler problem and expediting convergence. Moreover, LESSON provides a tunable trade-off between model accuracy and convergence rate by setting varying deadlines. Simulation results show that LESSON outperforms two baseline methods, namely FedAvg and FedCS, in terms of convergence speed and maintains higher model accuracy compared to FedCS.

     
    more » « less
    Free, publicly-accessible full text available November 1, 2024
  3. Free, publicly-accessible full text available August 1, 2024
  4. A high-gain SIW elliptically polarized antenna combination of a dipole and loop antenna based on substrate-integrated waveguide (SIW) is proposed for millimeter-wave (mm-wave) applications. The dipole and loop antenna are differentially excited by a longitudinal slot etched on the top layer of SIW. The proposed combination of dipole and loop antenna forms a parallel electric dipole and magnetic dipole, which radiates two orthogonal electric field components and 90∘ phase difference in the far-field radiation when they are excited with the same phased signal. The proposed antenna achieves a realized gain of 8.346 dBi, with a radiation efficiency of 89.40% at 60 GHz. 
    more » « less
    Free, publicly-accessible full text available July 23, 2024
  5. This paper presents the design and simulation of a 24 GHz 1×5 series-fed microstrip patch antenna array and its performance analysis with structural deformation. The optimized design comprises of 5 antenna elements arranged in series, where the entire design is symmetric about the center antenna element. The parameters such as S11 , gain vs. theta plots are analyzed with and without the material deformation. The shape deformation analysis is indeed needed to determine the performance efficiency of the designed antenna when deployed on drones, where the antenna needs to be flexible enough to be aligned with the curvature of drone's body. The simulation results are analyzed to see how best can the proposed antenna array can perform with the structural deformation. 
    more » « less
    Free, publicly-accessible full text available July 23, 2024
  6. This paper presents a high-gain and broadband radial elliptical-slot array (RESA) antenna with side-lobe mitigation technique for low-cost satellite communication systems. The aperture of the proposed slot array antenna comprises a set of orthogonal elliptical slots with monotonic slot length variation alongside the radius of the aperture. The design comprises radiating slotted top plate and bottom ground plate parallel to one another separated by an optimal distance of 5.25 mm which is 1.05λ . The design is back-fed using a disk-head radiator probe. The overall dimensions of the proposed slot array antenna with the air-gap taken into account are 300×300×5.75mm3 . Simulation results show that the proposed slot array antenna has a broadband operating frequency range from 45 GHz to 110 GHz and beyond, covering both V and W frequency bands with a fractional bandwidth of 88.8%. The peak gain of the proposed design is 35.6 dBi at 60 GHz. The array exhibits a maximum half-power beam width of 9.5°, a low sidelobe magnitude of - 4.12 dBi and a overall simple design indicates its suitability for low-cost SATCOM (satellite communications) applications. 
    more » « less
    Free, publicly-accessible full text available July 23, 2024