Image and Video Processing
FedASAP: Activation Statistics-driven Structured Adaptive Pruning for Efficient Personalized Federated Learning for Lesion Segmentation on brain MRI
Karan R. Bagri, Tarun K. Garg and Vaanathi Sundaresan
In medical imaging, developing robust deep learning models requires data from various domains. However, regulatory policies protecting patient
privacy restrict data sharing.
Federated learning (FL) addresses this by enabling collaborative model training without centralizing data. Yet, data heterogeneity across client centers requires personalized models to enhance performance. Clients with limited resources may struggle to efficiently train or deploy large deep neural networks. Adaptive model
pruning tackles both challenges by reducing model size while enabling personalized FL adaptation. Although research has investigated adaptive
pruning methods in FL, their effectiveness on dense prediction tasks like
segmentation remains unexplored. To address this gap, we propose Activation Statistics-driven structured Adaptive
Pruning (FedASAP), which uses activation-based features to guide filter removal for each client. By learning a lightweight classifier on per-filter activation statistics, FedASAP refines importance-score rankings and produces compact, personalized
segmentation models in heterogeneous
federated settings. Our results show the approach's effectiveness by achieving better Dice scores of 0.796 and 0.743, than state-of-the-art, while reducing parameter count by 45% and 73% on two multi-centric
brain pathology
segmentation datasets:
Federated Tumour
Segmentation (FeTS) and White Matter Hyperintensities (WMH), respectively.
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Signal Processing
Reconfigurable Holographic Surface for Simultaneous Wireless Information and Power Transfer
Yuan Guo, Wen Chen, Ziwei Liu et al. (+3 more)
In this paper, we propose to use a novel reconfigurable
holographic surface (RHS) to improve the performance of simultaneous wireless information and power transfer (SWIPT) by exploiting the additional spatial degrees of freedom (DoFs) enabled by the
holographic interference principle. Specifically, we study an RHS-empowered SWIPT system in which the digital beamformer at the base station (BS) and the
holographic beamformer at the RHS are jointly optimized to maximize the weighted sum-rate of information-decoding (ID) users while guaranteeing a minimum harvested energy requirement for each energy-harvesting (EH) user. Due to the non-convexity of the optimization problem, the weighted sum-rate maximization problem is challenging to solve. We first adopt the weighted minimum mean squared error (WMMSE) method to transform the objective into a more tractable form. We then develop an iterative optimization framework, where the BS digital beamforming and the RHS
holographic beamforming subproblems are solved via the majorization-minimization (MM) method. Since solving each subproblem can incur prohibitive complexity as the variable dimension increases, we further propose low-complexity solutions for the two subproblems based on the alternating direction method of multipliers (ADMM) methodology. Numerical results validate the convergence behavior of the proposed
algorithms and demonstrate that the RHS-aided BS achieves significant performance gains over a conventional fully-digital BS
benchmark. Moreover, the proposed low-complexity
algorithms substantially reduce computational complexity while maintaining nearly the same performance.
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All authors Yuan Guo, Wen Chen, Ziwei Liu, Chaoying Huang, Zhendong Li, Ying Wang
Audio and Speech Processing · Cross-listed from cs.SD
Variable-Rate Harmonic-Percussive Time-Scale Modification with Real-Time Playback in Python
Sayema Lubis, Clark Peng, Jared Carreño et al. (+1 more)
Time-scale modification (TSM) has a number of open-source implementations, but these are designed almost exclusively for offline use, in which a recording is processed at a fixed rate and written out ahead of time. Applications such as automatic musical accompaniment require a different setting, which we call variable-rate playback: the recording to be stretched is known in advance, but the playback rate is not, and must change continuously in response to a live performer. The few implementations that generate output in real time are written in C++ and optimized for speed rather than for ease of modification, experimentation, and integration with the primarily Python-based research ecosystem. This paper describes a Python implementation of the widely used harmonic-percussive TSM method for the variable-rate playback setting. Harmonic-percussive separation is performed offline as a preprocessing step on the known input recording, while synthesis and playback are carried out in real time with a time-scale factor that may change at every frame. We further propose a family of variants that reduce runtime by replacing the phase vocoder's analysis-stage FFT and instantaneous frequency calculations with lookups into precomputed tables. Subjective listening tests with 24 participants (1114 pairwise ratings) show that these approximations become perceptually indistinguishable from the exact implementation once the precomputed hop size is sufficiently small, while reducing total runtime by roughly half. We characterize the resulting tradeoffs among precomputation, runtime,
memory, and perceptual quality to guide
algorithm selection, and we release our implementation as an open-source package.
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All authors Sayema Lubis, Clark Peng, Jared Carreño, TJ Tsai
Signal Processing · Cross-listed from cs.RO
Two-Stage Extrinsic Calibration of a Static Line-Scanning Lidar with a Rotary Platform
Vikram Shree, Hike Danakian, Long Nguyen et al. (+2 more)
A line-scanning
lidar yields range and azimuth values in a fixed plane. To perceive surrounding objects in 3D, there must be relative motion between the
lidar plane and the object. Thus, using a rotating base-platform is promising for industrial applications where objects need to be scanned or inspected precisely, and is the main focus of this work. In the rotary platform setup, a 3D point cloud of an object can be constructed if the axis of rotation and the precise motion about that axis are known. However, this setup gives rise to the following problem: how can the axis of rotation of the platform be accurately identified with respect to the
lidar coordinate system? It is referred to as the calibration problem in the robotics community. Any inaccuracy in this transformation directly affects the quality of the reconstructed point cloud, leading to misrepresentation of the object of interest. In this work, we explore automated approaches to statically and dynamically estimate the transformation of a rotary platform's axis of rotation with respect to a static line-scanning
lidar. The proposed
algorithms have been validated on real-world
datasets obtained from a custom made rotary platform and an FMCW
lidar, and their convergence characteristics are studied for various initial conditions.
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All authors Vikram Shree, Hike Danakian, Long Nguyen, Rajanish Gokidi, Patrick Nercessian
Systems and Control
Integrity-Gated Eco-CACC: Epistemic Admissibility for Cooperative Driving at Signalized Intersections
Lyes Saad Saoud and Moussa Ayyash
Eco-Cooperative Adaptive Cruise Control (Eco-CACC) systems rely on accurate localization, signal timing, and interaction awareness to optimize energy consumption at signalized intersections. Existing approaches typically assume that the internal world model used for optimization remains valid, making them vulnerable when sensing outages or semantic inconsistencies invalidate planning premises. This letter proposes an Integrity-Gated Eco-CACC framework that explicitly monitors the consistency between internal vehicle beliefs and external sensing. A unified integrity metric is constructed by combining positional innovation, observability loss, and semantic inconsistencies. The resulting trust score regulates control authority, enabling a transition between nominal eco-driving and a safety-dominant fallback maneuver. Unlike robust control methods that attempt to preserve performance under uncertainty, the proposed framework regulates whether energy-optimal control remains admissible. Scenario-based simulations demonstrate that the method preserves nominal efficiency when model consistency is maintained, while enabling early and conservative responses under integrity degradation.
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Systems and Control · Cross-listed from cs.AI
Engineering Trustworthy Agentic AI for Critical Systems
Omar Al-Refai, Ibrahim Shahbaz, Adam Ali Husseinat et al. (+3 more)
Agentic artificial intelligence systems, capable of autonomous perception, planning, tool use, and multi-step action, are increasingly proposed for critical engineering domains where decisions carry physical, operational, or economic consequences. This survey addresses a gap in current literature by treating trustworthiness, whether agentic behavior can be verified, audited, and trusted under the constraints that engineering practice actually requires, as a first-class engineering property, rather than evaluating agentic AI by task capability alone. The study adopts a trustworthiness model organized around five cross-cutting dimensions: safety and constraint satisfaction; robustness and reliability; transparency and interpretability; accountability and auditability; and
privacy and security. This is mapped onto an agentic assurance workflow spanning perception through audit. Building on this foundation, agentic systems architectures, threats, concrete trust mechanisms, and quantitative metrics are surveyed for direct application in agentic systems development and evaluation. These principles are then examined across four constraint-bound engineering domains: power systems, autonomous vehicles/robotics/
UAVs, high-performance computing, and communication networks, identifying recurring design patterns, shared failure modes, and domain-specific gaps. Synthesizing across those domains, agentic AI trustworthiness is shown to be a single problem, with a path outlined toward a reusable, cross-domain assurance framework analogous to the graded certification regimes used by mature safety-critical engineering fields.
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All authors Omar Al-Refai, Ibrahim Shahbaz, Adam Ali Husseinat, Michael Mandulak, Jaewon Kim, Eman Hammad
Systems and Control
Large-Signal Stability Analysis of Optimization-Based Secondary Control for Distributed Energy Resources
Vivek Khatana, Soham Chakraborty and Murti V. Salapaka
This article develops a large-signal stability analysis for a sampled-data optimization-based secondary controller for distributed energy resources (DERs) in power systems. The induced closed loop combines nonlinear inverter power-flow dynamics, filtered active and reactive power measurements, constrained optimization updates, and interpolation-based actuation between sampling instants. We study this optimization-in-the-loop nonlinear sampled-data system beyond local linearization. The analysis provides computable bounds on the voltage, filtered reactive power, and the secondary control input. We further characterize steady-state operating points and establish how the optimizer objectives and constraints connect voltage regulation with equal per-unitized reactive power sharing. Finally, input-to-state stability of the frequency dynamics is established with respect to DER voltages and control inputs. These results provide a rigorous mathematical foundation for sampled-data optimization-based secondary control of DERs.
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Systems and Control · Cross-listed from cs.RO
The Open Ant: A Robot Platform for Reinforcement Learning Research
Elena Sorina Lupu, Patrick Spieler, Khurram Javed et al. (+4 more)
Reinforcement learning (RL) research has demonstrated success in both physical and simulated domains; however, the predominant methodology remains rooted in simulations. The predominance of simulations makes translating research to physical reality uncertain for both
algorithms and researchers. We propose a physical platform that is designed to simplify the transition. In this paper, we present the Open Ant: a physical variant of the commonly used Gymnasium Ant environment, along with a simulation. We demonstrate that competent walking policies can be learned from scratch in approximately one hour directly from the physical
robot's experience for two substantially different RL
algorithms: SARSA($\lambda$) and Soft Actor-Critic (SAC). Separately, we show policies that were learned in simulation transfer to reality. We also examine how well the platform supports a nimble experimental ecosystem. Specifically, we observe the speed with which new users from diverse backgrounds achieve their first success with the platform, and how easily the platform can be repaired and updated when hardware issues arise. Both the hardware design and software are available as open-source on GitHub for ease of customization. In summary, we advocate for the use of the Open Ant for RL researchers who frequently use simulated environments, so they can more easily include
robot experiments in their evaluations.
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All authors Elena Sorina Lupu, Patrick Spieler, Khurram Javed, Kris De Asis, John D. Martin, Martha Steenstrup, Joseph Modayil
Systems and Control · Cross-listed from cs.CY
Governing Well in the Algorithmic Age: The Foundations of Digital Statecraft
Zeynep Engin, Tim Gordon, Viviana Bastidas et al. (+14 more)
The digital substrate - data,
algorithms, infrastructure, platforms, applications - is being governed without adequate conceptual foundations. The ability and legitimacy required to govern this substrate, and to govern with it, are simultaneously misaligned, contested, and structurally absent. We introduce digital statecraft as the organising concept for this emerging field, arguing that 'digital' reconstitutes the statecraft question rather than merely extending its domain. The concept operates on two dimensions - statecraft over digital systems, concerning the authority and capacity of the state in relation to the digital substrate itself, and statecraft with digital systems, concerning the deployment of algorithmic tools as instruments of governing authority. And it rests on two foundational requirements, technical coherence and legitimate authority, that are genuinely in tension. We derive ten principles of digital statecraft from these foundations, each naming a condition whose absence produces an identifiable and structural governance failure: public interest first, human-machine complementarity, governability by design, systemic coherence, hybrid institutions, adaptive governance, human centricity and civic agency, accountable and traceable authority, judgment across time, and the non-delegable core. This article takes the state as the starting point, the institutional form that developed historically in response to the problem of effective and legitimate public governance, and the only current candidate for which the full set of legitimacy conditions is institutionally available. But the digital statecraft programme holds open a deeper question than just whether states can reform themselves: governing well in the algorithmic age may require rethinking the boundaries, scale, and affiliative basis of statehood itself.
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All authors Zeynep Engin, Tim Gordon, Viviana Bastidas, Tom Crick, Jon Crowcroft, Jean-Martin Denis, David J. Hand, Ed Humpherson, Lauren Maffeo, Jakob Mökander, Irene Ng, Anastasija Nikiforova, Giulio Quaggiotto, David Uriel Socol de la Osa, Rhonda Syler, Philip Treleaven, Stefaan Verhulst
Signal Processing
Long-Horizon Wireless Link Scheduling with State-Augmented Graph Neural Networks
Romina Garcia Camargo, Zhiyang Wang, Navid NaderiAlizadeh et al. (+1 more)
We address optimal link scheduling in large-scale wireless networks. The goal is to schedule transmissions over a time horizon so that to maximize sum rate while ensuring that average rates of each customer attain a minimum rate requirement. To this end, we formulate a constrained optimization problem and solve it using Lagrangian duality. Common primal-dual approaches lead to time invariant policies. Our constraint requires all links transmit a fraction of the time while avoiding interference, which calls for time-varying policies across time slots. We propose an iterative
algorithm to sample optimal sequences of schedules and dual variables. The scheduling decisions are parameterized using a Graph Neural Network. We incorporate state-augmentation techniques to learn said parameterization, introducing dual variables as dynamic inputs to the policy. This augmentation enables the GNN to adapt scheduling decisions over time, balancing constraint satisfaction with performance maximization. We validate our approach through extensive numerical simulations, benchmarking against several baselines and considering varying constraint levels.
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All authors Romina Garcia Camargo, Zhiyang Wang, Navid NaderiAlizadeh, Alejandro Ribeiro
Signal Processing
Blind Adaptive Equalization in Additive Impulsive Noise Using the Logarithmic Product Fractional-Moment (LP-FM) Criterion
Shafayat Abrar
The blind mitigation of inter-symbol interference in additive white impulsive noise modeled by a symmetric $\alpha$-stable (S$\alpha$S) distribution is investigated. A novel logarithmic product fractional-moment statistics (LP-FMS) criterion is proposed by combining complementary fractional-moment statistics with logarithmic normalization in a constrained optimization framework. Based on this criterion, a normalized blind equalization
algorithm for symmetric alpha-stable noise (NBEA-SAS) is derived using
stochastic gradient ascent with recursive fractional-moment estimation and Bussgang-consistent constrained adaptation. Simulation results for $64$-APSK signaling over fractionally spaced multipath microwave channels show that the proposed
algorithm converges faster than FLOS-CMA, RAW-CMA, and NBEA-GG while achieving a comparable steady-state residual intersymbol interference floor under both moderately and highly impulsive S$\alpha$S noise conditions. The results demonstrate that the proposed LP-FMS criterion provides a robust framework for blind adaptive equalization in impulsive noise environments.
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Systems and Control · Cross-listed from cond-mat.mes-hall
Supriyo Bandyopadhyay
Antennas transmit information wirelessly from one location to another via electromagnetic waves. Miniaturizing them, however, is challenging since the radiation efficiencies of all traditional
antennas, based on the principles of classical electromagnetics, plummet when their dimensions are shrunk to tiny fractions of the radiated wavelength. Lately, a new generation of
antennas whose operations are underpinned by non-classical principles have been demonstrated and they can overcome this limitation. This enables embedded applications that were hitherto inaccessible. In addition, beam steering, which normally requires a large phased array (multiple
antenna elements each much larger than the wavelength), can now be accomplished with a single element much smaller than the wavelength. Some of these
antennas also have stealth attributes for secure and covert communication, which makes this new genre a disruptive new technology.
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Systems and Control
Learnable Sequential Memory in Coupled Oscillator Networks
Taosha Guo and Fabio Pasqualetti
The Hopfield network established that static
memories can be stored as energy minima of a recurrent dynamical system, yet real intelligent
agents must navigate sequences of
memories rather than isolated snapshots.Biological cortex addresses this through a separation of timescales: fast synaptic dynamics encode individual states while slow neuromodulatory processes govern transitions between them. Inspired by this multi-timescale organization, we propose a sequential
memory architecture that is fully continuous, admits exponential storage capacity, and is learnable in the sense that the transition structure is carried by a separate routing
matrix – decoupled from the stored patterns, driven by the input context, and free to be chosen, optimized, or learned from data rather than hard-wired into the
memory substrate. Specifically, we construct an autonomous three-timescale dynamical system with three coupled layers: a fast Kuramoto layer that stores phase patterns as exponentially stable phase-locked configurations, an intermediate hysteresis layer that enforces reliable dwell times, and a slow
attention layer that routes sequential transitions. We provide a complete theoretical analysis of the stability and robustness of each layer, and we validate the full system through numerical simulations of sequential
memory retrieval.
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Systems and Control · Cross-listed from math.OC
$\texttt{codesign-mcdp}$: A Python Library for Monotone Co-Design Problems
Corentin Briat
$\texttt{codesign-mcdp}$ is a Python library for formulating and solving $\textit{Monotone Co-Design Problems}$ (MCDPs) in the framework of Censi (2015). A design problem is a relation between two posets, a functionality poset $F$ and a resource poset $R$; given a target functionality, the problem asks for the antichain of minimal resources needed to deliver it. Design problems compose under three operators (series, parallel, feedback), and the resulting class is closed under composition. The library implements the antichain calculus, six primitive design-problem types, the three composition operators, a Kleene fixed-point solver, and two high-level builders (an MCDPL-style declarative builder and a modular $\texttt{System}$ builder). Further layers add set-based and
stochastic uncertainty, compositional online learning, and temporal, vector-state, and online co-design, alongside a suite of worked examples.
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Systems and Control · Cross-listed from cs.RO
Towards Torque-Driven Reinforcement Learning for Quadruped Locomotion
Jordan Dowdy and Jean Chagas Vaz
Reinforcement learning (RL) for legged
robots is advancing locomotion, demonstrating its ability to adapt to new and challenging terrain. Traditionally, these RL locomotion frameworks are position-based, making the policy less adaptable to terrain types and requiring state estimation techniques in the observation space, i.e., linear velocity. Moreover, these RL frameworks often use small, lightweight quadrupeds that are limited in their viability for high-complexity tasks due to hardware constraints. This work explores an RL torque control framework for heavyweight high-torque quadrupeds. The RL framework in this paper can traverse rough terrain and effectively track a desired linear velocity without requiring knowledge of the
agent's current velocity. Using Nvidia's Isaac Sim and Isaac Lab, simulation results of the RL torque control policy are shown on the Unitree B1 quadruped, achieving speeds of 3.5 m/s and 1.5 rad/s. In addition, the quadruped can walk up and down stairs without the aid of an exteroceptive sensor.
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Signal Processing · Cross-listed from cs.LG
Multi-layer MIMO Relay as Deep Physical Neural Networks: Power Amplifiers as Activation Functions
Meng Hua, Itsik Bergel and Deniz Gündüz
Wireless physical neural networks (WPNNs) embed neural computation directly into analog hardware, offering lower energy consumption and latency than conventional digital implementations. In this paper, we propose a deep WPNN in which nonlinear activations are realized by a multi-hop multiple-input multiple-output (
MIMO) relay network, in which each relay implements a trainable complex linear gain and bias, followed by the power amplifier's intrinsic nonlinearity acting as an activation function. The cascade of multiple relays therefore realizes an over-the-air fully connected network whose parameters can be trained end-to-end. We develop two transceiver designs for different channel state information (CSI) availability scenarios: a least squares (LS)-based scheme requiring only receiver-side CSI, and a singular-value-decomposition (SVD)-based scheme requiring both transmitter-side and receiver-side CSI. Simulation results show that the proposed architecture enables accurate over-the-air inference for image classification. In particular, the results highlight the advantage of exploiting hardware nonlinearity for enhanced inference capability.
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