Signal Processing
High-Resolution Range Profile Classifiers Require Aspect-Angle Awareness
Edwyn Brient, Santiago Velasco-Forero and Rami Kassab
We revisit High-Resolution Range Profile (HRRP) classification with aspect-angle conditioning. While prior work often assumes that aspect-angle information is incomplete during training or unavailable at inference, we study a setting where angles are available for all training samples and explicitly provided to the classifier. Using three
datasets and a broad range of conditioning strategies and model architectures, we show that both single-profile and sequential classifiers benefit consistently from aspect-angle awareness, with an average accuracy gain of about 7% and improvements of up to 10%, depending on the model and
dataset. In practice, aspect angles are not directly measured and must be estimated. We show that a causal Kalman filter can estimate them online with a median error of 5{\textdegree}, and that training and inference with estimated angles preserves most of the gains, supporting the proposed approach in realistic conditions.
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Audio and Speech Processing · Cross-listed from cs.CL
Iterative LLM-based improvement for French Clinical Interview Transcription and Speaker Diarization
Ambre Marie, Thomas Bertin, Guillaume Dardenne et al. (+1 more)
Automatic
speech recognition for French medical conversations remains challenging, with word error rates often exceeding 30% in spontaneous clinical
speech. This study proposes a multi-pass LLM post-processing architecture alternating between Speaker Recognition and Word Recognition passes to improve transcription accuracy and speaker attribution. Ablation studies on two French clinical
datasets (suicide prevention telephone counseling and preoperative awake neurosurgery consultations) investigate four design choices: model selection, prompting strategy, pass ordering, and iteration depth. Using Qwen3-Next-80B, Wilcoxon signed-rank tests confirm significant WDER reductions on suicide prevention conversations (p<0.05, n=18), while maintaining stability on awake neurosurgery consultations (n=10), with zero output failures and acceptable computational cost (RTF 0.32), suggesting feasibility for offline clinical deployment, pending validation on larger corpora.
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All authors Ambre Marie, Thomas Bertin, Guillaume Dardenne, Gwenolé Quellec
Systems and Control · Cross-listed from cs.NE
Joint Sensor Deployment and Physics-Informed Graph Transformer for Smart Grid Attack Detection
Mariam Elnour, Mohammad AlShaikh Saleh, Rachad Atat et al. (+6 more)
This paper proposes a joint multi-objective optimization framework for strategic sensor placement in power systems to enhance attack detection. A novel physics-informed graph
transformer network (PIGTN)-based detection model is proposed. Non-dominated sorting genetic
algorithm-II (NSGA-II) jointly optimizes sensor locations and the PIGTN's detection performance, while considering practical constraints. The combinatorial space of feasible sensor placements is explored using NSGA-II, while concurrently training the proposed detector in a closed-loop setting. Compared to baseline sensor placement methods, the proposed framework consistently demonstrates robustness under sensor failures and improvements in detection performance in seven
benchmark cases, including the 14, 30, IEEE-30, 39, 57, 118 and the 200 bus systems. By incorporating AC power flow constraints, the proposed PIGTN-based detection model generalizes well to unseen attacks and outperforms other graph network-based variants (
topology-aware models), achieving improvements up to 37% in accuracy and 73% in detection rate, with a mean false alarms rate of 0.3%. In addition, optimized sensor layouts significantly improve the performance of power system state estimation, achieving a 61%–98% reduction in the average state error.
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All authors Mariam Elnour, Mohammad AlShaikh Saleh, Rachad Atat, Xiang Huo, Abdulrahman Takiddin, Muhammad Ismail, Hasan Kurban, Katherine R. Davis, Erchin Serpedin
Audio and Speech Processing · Cross-listed from cs.CL
Task-Lens: Cross-Task Utility Based Speech Dataset Profiling for Low-Resource Indian Languages
Swati Sharma, Divya V. Sharma and Anubha Gupta
The rising demand for inclusive
speech technologies amplifies the need for
multilingual datasets for Natural
Language Processing (NLP) research. However, limited awareness of existing task-specific resources in low-resource
languages hinders research. This challenge is especially acute in linguistically diverse countries, such as India. Cross-task profiling of existing Indian
speech datasets can alleviate the data scarcity challenge. This involves investigating the utility of
datasets across multiple downstream tasks rather than focusing on a single task. Prior surveys typically catalogue
datasets for a single task, leaving comprehensive cross-task profiling as an open opportunity. Therefore, we propose Task-Lens, a cross-task survey that assesses the readiness of 50 Indian
speech datasets spanning 26
languages for nine downstream
speech tasks. First, we analyze which
datasets contain metadata and properties suitable for specific tasks. Next, we propose task-aligned enhancements to unlock
datasets to their full downstream potential. Finally, we identify tasks and Indian
languages that are critically underserved by current resources. Our findings reveal that many Indian
speech datasets contain untapped metadata that can support multiple downstream tasks. By uncovering cross-task linkages and gaps, Task-Lens enables researchers to explore the broader applicability of existing
datasets and to prioritize
dataset creation for underserved tasks and
languages.
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Audio and Speech Processing · Cross-listed from cs.SD
Hello-Chat: Towards Realistic Social Audio Interactions
Yueran Hou, Peilei Jia, Zihan Sun et al. (+5 more)
Recent advancements in Large Audio
Language Models (LALMs) have demonstrated exceptional performance in
speech recognition and translation. However, existing models often suffer from a disconnect between perception and expression, resulting in a robotic "read-
speech" style that lacks the spontaneity and emotional resonance of real human interaction. In this report, we introduce Hello-Chat, an end-to-end audio
language model designed for realistic social scenarios. By leveraging a massive
dataset of real-life conversations and employing a modality-interleaved training strategy, Hello-Chat achieves a breakthrough in anthropomorphic generation. Experimental results show that our model not only reaches state-of-the-art (SOTA) performance on specific audio understanding tasks but also significantly outperforms existing baselines in prosodic naturalness and emotional
alignment, paving the way for the next generation of empathetic AI
agents.
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All authors Yueran Hou, Peilei Jia, Zihan Sun, Qihang Lu, Wenbing Yang, Yingming Gao, Ya Li, Jun Gao
Audio and Speech Processing
Resp-Agent: An Agent-Based System for Multimodal Respiratory Sound Generation and Disease Diagnosis
Pengfei Zhang, Tianxin Xie, Minghao Yang et al. (+1 more)
Deep learning-based respiratory auscultation is currently hindered by two fundamental challenges: (i) inherent information loss, as converting signals into spectrograms discards transient acoustic events and clinical context; (ii) limited data availability, exacerbated by severe class imbalance. To bridge these gaps, we present Resp-
Agent, an autonomous
multimodal system orchestrated by a novel Active
Adversarial Curriculum
Agent (Thinker-A$^2$CA). Unlike static pipelines, Thinker-A$^2$CA serves as a central controller that actively identifies diagnostic weaknesses and schedules targeted synthesis in a closed loop. To address the representation gap, we introduce a modality-weaving Diagnoser that weaves clinical text with audio
tokens via strategic global
attention and sparse audio anchors, capturing both long-range clinical context and millisecond-level transients. To address the data gap, we design a flow matching Generator that adapts a text-only Large
Language Model (LLM) via modality injection, decoupling pathological content from acoustic style to synthesize hard-to-diagnose samples. As a foundation for this work, we introduce Resp-229k, a
benchmark corpus of 229k recordings paired with LLM-distilled clinical narratives. Extensive experiments demonstrate that Resp-
Agent consistently outperforms prior approaches across diverse evaluation settings, improving diagnostic robustness under data scarcity and long-tailed class imbalance. Our code and data are available at https://github.com/zpforlove/Resp-
Agent.
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All authors Pengfei Zhang, Tianxin Xie, Minghao Yang, Li Liu
Systems and Control
Embedding Economic Input-Output Models in Systems of Systems: An MBSE and Hetero-functional Graph Theory Approach
Mohammad Mhadi Naderi, Megan S. Harris, John C. Little et al. (+1 more)
Characterizing the interdependent nature of Anthropocene systems of systems is fundamental to making informed decisions to address challenges across complex ecological, environmental, and coupled human-natural systems. This paper presents the first application of Model-Based Systems Engineering (MBSE) and Hetero-functional Graph Theory (HFGT) to economic systems, establishing a scalable and extensible methodology for integrating economic input-output (EIO) models within a unified system-of-systems modeling framework. Integrating EIO models into the MBSE-HFGT workflow demonstrates how the structural form and function of economic systems can be expressed through SysML's graphical ontology and subsequently translated into the computational structure of HFGT. Using a synthetic Rectangular Choice of Technology (RCOT) example as a pedagogical foundation, the study confirms that the dynamics captured by basic EIO models, as well as other complex economic models grounded in EIO theory, can be equivalently reproduced within the MBSE-HFGT framework. The integration with MBSE and HFGT thus preserves analytical precision while offering enhanced graphical clarity and system-level insight through a shared ontological structure. By integrating modeling
languages and mathematical frameworks, the proposed methodology establishes a foundation for knowledge co-production and integrated decision-making to address the multifaceted sustainability challenges associated with Anthropocene systems of systems.
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All authors Mohammad Mhadi Naderi, Megan S. Harris, John C. Little, Amro M. Farid
Signal Processing
Multiplierless DFT Approximation Based on the Prime Factor Algorithm
L. Portella, F. M. Bayer and R. J. Cintra
Matrix approximation methods have successfully produced efficient, low-complexity approximate transforms for the discrete cosine transforms and the discrete
Fourier transforms. For the DFT case, literature archives approximations operating at small power-of-two blocklenghts, such as \{8, 16, 32\}, or at large blocklengths, such as 1024, which are obtained by means of the Cooley-Tukey-based approximation relying on the small-blocklength approximate transforms. Cooley-Tukey-based approximations inherit the intermediate multiplications by twiddled factors which are usually not approximated; otherwise the effected error propagation would prevent the overall good performance of the approximation. In this context, the
prime factor
algorithm can furnish the necessary framework for deriving fully multiplierless DFT approximations. We introduced an approximation method based on small
prime-sized DFT approximations which entirely eliminates intermediate multiplication steps and prevents internal error propagation. To demonstrate the proposed method, we design a fully multiplierless 1023-point DFT approximation based on 3-, 11- and 31-point DFT approximations. The performance evaluation according to popular metrics showed that the proposed approximations not only presented a significantly lower arithmetic complexity but also resulted in smaller approximation error measurements when compared to competing methods.
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Signal Processing
Secure High-Resolution ISAC via Multi-Layer Intelligent Metasurfaces: A Layered Optimization Framework
Amirhossein Taherpour, Abbas Taherpour and Tamer Khattab
Integrated sensing and communication (
ISAC) has emerged as a pivotal technology for next-generation wireless networks, enabling simultaneous data transmission and environmental sensing. However, existing
ISAC systems face fundamental limitations in achieving high-resolution sensing while maintaining robust communication security and spectral efficiency. This paper introduces a transformative approach leveraging stacked intelligent metasurfaces (SIM) to overcome these challenges. We propose a multi-functional SIM-assisted system that jointly optimizes communication secrecy and sensing accuracy through a novel layered optimization framework. Our solution employs a multi-objective optimization formulation that balances secrecy rate maximization with sensing error minimization under practical hardware constraints. The proposed layered block coordinate descent
algorithm efficiently coordinates sensing configuration, secure beamforming, communication metasurface optimization, and resource allocation while ensuring robustness to channel uncertainties. Extensive simulations demonstrate significant performance gains over conventional approaches, achieving 32-61% improvement in sensing accuracy and 15-35% enhancement in secrecy rates while maintaining computational efficiency. This work establishes a new paradigm for secure and high-precision multi-functional wireless systems.
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Signal Processing · Cross-listed from quant-ph
Tomography by Design: An Algebraic Approach to Low-Rank Quantum States
Shakir Showkat Sofi, Charlotte Vermeylen and Lieven De Lathauwer
We present an algebraic
algorithm for
quantum state
tomography that leverages measurements of certain observables to estimate structured entries of the underlying density
matrix. Under low-rank assumptions, the remaining entries can be obtained solely using standard numerical linear
algebra operations. The proposed algebraic
matrix completion framework applies to a broad class of generic, low-rank mixed
quantum states and, compared with state-of-the-art methods, is computationally efficient while providing deterministic recovery guarantees.
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Signal Processing
Large elements and advanced beamformers for increased field of view in 2-D ultrasound matrix arrays
Mick Gardner and Michael L. Oelze
Three-dimensional (3D) ultrasound promises various medical applications for abdominal, obstetrics, and breast imaging. However, ultrasound
matrix arrays have extremely high element counts limiting their field of view (FOV). Current reduced element count architectures, such as row-column arrays, diverging lenses, or sparse arrays, suffer from limited resolution and high side- and grating-lobe levels. This work seeks to demonstrate an increased field-of-view using a reduced element count array design. The approach is to increase the element size and use advanced beamformers to maintain image quality. The delay and sum (DAS), Null Subtraction Imaging (NSI), directional coherence factor (DCF), and Minimum Variance (MV) beamformers were compared. K-wave simulations of the 3D point-spread functions (PSF) of NSI, DCF, and MV display reduced side lobes and narrowed main lobes compared to DAS. Experiments were conducted using a multiplexed 1024-element
matrix array on a Verasonics 256 system. Elements were electronically coupled to imitate a larger pitch and element size. Then, a virtual large aperture was created by using a positioning system to collect data in sections with the
matrix array. Resolution and contrast was also assessed on a rabbit liver in vivo. Resolution was maintained using coupling numbers up to four, doubling the FOV while reducing the element count. The NSI and DCF beamformers demonstrated the best resolution performance in simulations, in a phantom with the virtual aperture, and in vivo on a rabbit liver. Our results demonstrate how larger
matrix arrays could be constructed with larger elements, with resolution maintained by advanced beamformers.
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Image and Video Processing
StrokeNeXt: A Siamese-encoder Approach for Brain Stroke Classification in Computed Tomography Imagery
Leo Thomas Ramos and Angel D. Sappa
We present StrokeNeXt, a model for stroke classification in 2D Computed
Tomography (CT) images. StrokeNeXt employs a dual-branch design with two ConvNeXt encoders, whose features are fused through a lightweight convolutional decoder based on stacked 1D operations, including a bottleneck projection and transformation layers, and a compact classification head. The model is evaluated on a curated
dataset of 6,774 CT images, addressing both stroke detection and subtype classification between ischemic and hemorrhage cases. StrokeNeXt consistently outperforms convolutional and
Transformer-based baselines, reaching accuracies and F1-scores of up to 0.988. Paired statistical tests confirm that the performance gains are statistically significant, while class-wise sensitivity and specificity demonstrate robust behavior across diagnostic categories. Calibration analysis shows reduced prediction error compared to competing methods, and confusion
matrix results indicate low misclassification rates. In addition, the model exhibits low inference time and fast convergence.
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Signal Processing
Real-time Range-Angle Estimation and Tag Localization for Multi-static Backscatter Systems
Tara Esmaeilbeig, Kartik Patel, Traian E. Abrudan et al. (+3 more)
Multi-static backscatter networks (BNs) are strong candidates for joint communication and localization in the ambient IoT paradigm for 6G. Enabling real-time localization in large-scale multi-static deployments with thousands of devices require highly efficient
algorithms for estimating key parameters such as range and angle of arrival (AoA), and for fusing these parameters into location estimates. We propose two low-complexity
algorithms, Joint Range-Angle Clustering (JRAC) and Stage-wise Range-Angle Estimation (SRAE). Both deliver range and angle estimation accuracy comparable to FFT- and subspace-based baselines while significantly reducing the computation. We then introduce two real-time localization
algorithms that fuse the estimated ranges and AoAs: a maximum-likelihood (ML) method solved via gradient search and an iterative re-weighted least squares (IRLS) method. Both achieve localization accuracy comparable to ML-based brute force search albeit with far lower complexity. Experiments on a real-world large-scale multi-static testbed with 4 illuminators, 1 multi-
antenna receiver, and 100 tags show that JRAC and SRAE reduce runtime by up to 40X and IRLS achieves up to 500X reduction over ML-based brute force search without degrading localization accuracy. The proposed methods achieve 3 m median localization error across all 100 tags in a sub-6GHz band with 40 MHz bandwidth. These results demonstrate that multi-static range-angle estimation and localization
algorithms can make real-time, scalable backscatter localization practical for next-generation ambient IoT networks.
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All authors Tara Esmaeilbeig, Kartik Patel, Traian E. Abrudan, John Kimionis, Eleftherios Kampianakis, Michael S. Eggleston
Systems and Control · Cross-listed from cs.RO
Kalman Filtering Based Flight Management System Modeling for AAM Aircraft
Balram Kandoria and Aryaman Singh Samyal
Advanced Air Mobility (AAM) operations are planned to utilize strategic flight planning services that predict temporal uncertainties to validate flight plans against hazards such as weather
cells, restricted airspaces, and CNS disruption areas. This paper presents a Kalman Filter-based uncertainty propagation method that models Flight Management System (FMS) correction behavior through a sigmoid-blended measurement noise covariance. The sigmoid formulation generalizes existing discrete FMS activation thresholds into a continuous, tunable function that smoothly transitions the filter's measurement noise based on progress toward each waypoint. When the measurement noise is high, due to an inverse relationship, the Kalman gain is small and thus uncertainty grows; as the aircraft nears a waypoint, measurement noise decreases as a function of progress, the Kalman gain increases, and state covariance contracts which models the FMS progressively correcting toward the planned trajectory. The approach is computationally efficient (up to two orders of magnitude faster than Monte Carlo methods), scales with control inputs, and is parametrically tunable for different classes of aircraft. The measurement noise covariance is calibrated using real Automatic Dependent Surveillance-Broadcast (ADS-B) data from commercial Instrument Flight Rules (IFR) flights serving as surrogates for future AAM operations, achieving coverage probability conservative relative to theoretical Gaussian predictions at the 1-sigma confidence level on a hold out verification
dataset (N = 36). Parameter sensitivity analysis across multiple flight routes demonstrates robust behavior, and comparative evaluation against Monte Carlo and Linear Propagation methods contextualizes the method's computational and accuracy trade-offs.
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Systems and Control
Gradient Networks for Universal Magnetic Modeling of Synchronous Machines
Junyi Li, Tim Foissner, Floran Martin et al. (+2 more)
This paper presents a physics-constrained neural network framework for
magnetic modeling of saturable synchronous machines, including spatial harmonics. By
embedding gradient networks into the machine equations to model conservative electromagnetic behavior, the framework satisfies reciprocity and energy conservation by construction, while universally approximating any physically feasible
magnetic characteristic. Unlike lookup tables and black-box neural networks, it guarantees monotonicity, invertibility, and smooth outputs, and remains highly data efficient. The method is validated using measured and finite-element method (FEM) data from a 5.6-kW permanent-magnet (PM) synchronous reluctance machine, and is demonstrated in real-time closed-loop control on an embedded platform. The results confirm accurate, physically consistent, and computationally efficient performance.
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All authors Junyi Li, Tim Foissner, Floran Martin, Antti Piippo, Marko Hinkkanen
Systems and Control
Fault Detection in Electrical Distribution System using Autoencoders
Sidharthenee Nayak, Victor Sam Moses Babu, Chandrashekhar Narayan Bhende et al. (+2 more)
In recent times, there has been considerable interest in fault detection within electrical power systems, garnering
attention from both academic researchers and industry professionals. Despite the development of numerous fault detection methods and their adaptations over the past decade, their practical application remains highly challenging. Given the probabilistic nature of fault occurrences and parameters, certain decision-making tasks could be approached from a probabilistic standpoint. Protective systems are tasked with the detection, classification, and localization of faulty voltage and current line magnitudes, culminating in the activation of
circuit breakers to isolate the faulty line. An essential aspect of designing effective fault detection systems lies in obtaining reliable data for training and testing, which is often scarce. Leveraging deep learning techniques, particularly the powerful capabilities of pattern classifiers in learning, generalizing, and parallel processing, offers promising avenues for intelligent fault detection. To address this, our paper proposes an anomaly-based approach for fault detection in electrical power systems, employing deep autoencoders. Additionally, we utilize Convolutional Autoencoders (CAE) for dimensionality reduction, which, due to its fewer parameters, requires less training time compared to conventional autoencoders. The proposed method demonstrates superior performance and accuracy compared to alternative detection approaches by achieving an accuracy of 97.62% and 99.92% on simulated and publicly available
datasets.
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All authors Sidharthenee Nayak, Victor Sam Moses Babu, Chandrashekhar Narayan Bhende, Pratyush Chakraborty, Mayukha Pal
Signal Processing
Lattice XBAR Filters in Thin-Film Lithium Niobate
Taran Anusorn, Byeongjin Kim, Ian Anderson et al. (+2 more)
This work presents the demonstration of
lattice filters based on laterally excited bulk acoustic resonators (XBARs). Two filter implementations, namely direct
lattice and layout-balanced
lattice topologies, are designed and fabricated in periodically poled piezoelectric film (P3F) thin-film lithium niobate (TFLN). By leveraging the strong electromechanical coupling of XBARs in P3F TFLN together with the inherently wideband nature of the
lattice topology, 3-dB fractional bandwidths (FBWs) of 27.42% and 39.11% and low insertion losses (ILs) of 0.88 dB and 0.96 dB are achieved at approximately 20 GHz for the direct and layout-balanced
lattice filters, respectively, under conjugate matching. Notably, all prototypes feature compact footprints smaller than 1.3 mm\textsuperscript{2}. These results highlight the potential of XBAR-based
lattice architectures to enable low-loss, wideband acoustic filters for compact, high-performance RF front ends in next-generation wireless communication and sensing systems, while also identifying key challenges and directions for further optimization.
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All authors Taran Anusorn, Byeongjin Kim, Ian Anderson, Ziqian Yao, Ruochen Lu
Image and Video Processing · Cross-listed from cs.LG
Coverage Guarantees for Pseudo-Calibrated Conformal Prediction under Distribution Shift
Farbod Siahkali, Ashwin Verma and Vijay Gupta
Conformal prediction (CP) offers distribution-free marginal coverage guarantees under an exchangeability assumption, but these guarantees can fail if the data distribution shifts. We analyze the use of pseudo-calibration as a tool to counter this performance loss under a bounded label-conditional
covariate shift model. Using tools from domain adaptation, we derive a lower bound on target coverage in terms of the source-domain loss of the classifier and a Wasserstein measure of the shift. Using this result, we provide a method to design pseudo-calibrated sets that inflate the conformal threshold by a slack parameter to keep target coverage above a prescribed level. Finally, we propose a source-tuned pseudo-calibration
algorithm that interpolates between hard pseudo-labels and randomized labels as a function of classifier uncertainty. Numerical experiments show that our bounds qualitatively track pseudo-calibration behavior and that the source-tuned scheme mitigates coverage degradation under distribution shift while maintaining nontrivial prediction set sizes.
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Systems and Control
Unified Eigenvalue-Eigenspace Criteria for Functional Properties of Linear Systems and the Generalized Separation Principle
Tyrone Fernando
Classical controllability and observability admit equivalent Popov-Belevitch-Hautus (PBH) tests based on
eigenvalue-wise rank conditions. This paper extends this framework to functional properties of linear systems, establishing necessary and sufficient PBH-style conditions for Functional Controllability, Functional Stabilizability, Functional Observability, and Functional Detectability in terms of generalized eigenspaces. By contrast, Target Output Controllability is shown not to admit an independent
eigenvalue-wise characterization in general; a necessary and sufficient eigenstructure condition is derived instead. We further introduce Intrinsic Functional Controllability and Intrinsic Functional Stabilizability, which give necessary and sufficient conditions for the existence of the augmentation
matrices required for functional controller and observer synthesis. These intrinsic properties yield a Generalized Separation Principle that recovers the classical separation principle as a special case.
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Signal Processing
RF-GPT: Teaching AI to See the Wireless World
Hang Zou, Yu Tian, Bohao Wang et al. (+4 more)
Large
language models (LLMs) and
multimodal models have become powerful general-purpose
reasoning systems. However,
radio-frequency (RF) signals, which underpin wireless systems, are still not natively supported by these models. Existing LLM-based approaches for telecom focus mainly on text and structured data, while conventional RF deep-learning models are built separately for specific signal-processing tasks, highlighting a clear gap between RF perception and high-level
reasoning. To bridge this gap, we introduce RF-GPT, a
radio-frequency
language model (RFLM) that utilizes the visual encoders of
multimodal LLMs to process and understand RF spectrograms. In this framework, complex in-phase/quadrature (IQ) waveforms are mapped to time-frequency spectrograms and then passed to pretrained visual encoders. The resulting representations are injected as RF
tokens into a decoder-only LLM, which generates RF-grounded answers, explanations, and structured outputs. To train RF-GPT, we perform supervised instruction fine-tuning of a pretrained
multimodal LLM using a fully synthetic RF corpus. Standards-compliant waveform generators produce wideband scenes for six wireless technologies, from which we derive time-frequency spectrograms, exact configuration metadata, and dense captions. A text-only LLM then converts these captions into RF-grounded instruction-answer pairs, yielding roughly 120,000 RF scenes and 0.625 million instruction examples without any manual labeling. Across
benchmarks for wideband modulation classification, overlap analysis, wireless-technology recognition, WLAN user counting, and 5G NR information extraction, RF-GPT achieves strong multi-task performance, whereas general-purpose VLMs with no RF grounding largely fail.
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All authors Hang Zou, Yu Tian, Bohao Wang, Lina Bariah, Samson Lasaulce, Chongwen Huang, Mérouane Debbah
Systems and Control · Cross-listed from math.OC
On Convergence Analysis of Network-GIANT: An approximate Hessian-based fully distributed optimization algorithm
Souvik Das, Luca Schenato and Subhrakanti Dey
This paper presents a detailed convergence and performance analysis of a recently developed approximate Newton-type fully distributed optimization method for \(L\)-smooth, \(\mu\)-strongly convex local loss functions, called Network-
GIANT (inspired by the
Federated learning
algorithm GIANT possessing mixed linear-quadratic convergence properties). Network-
GIANT has been empirically seen to achieve faster linear convergence properties compared to its gradient-based counterparts, and several other existing second order distributed
algorithms, while having the same communication complexity (per iteration) as its first order distributed counterparts. We first explicitly characterize a global linear convergence rate for Network-
GIANT, which can be computed as the spectral radius of a $3 \times 3$
matrix dependent on $L$, $\mu$, and the spectral norm ($\sigma$) of the consensus
matrix of the underlying undirected graph. We provide an explicit bound on the step size parameter $\eta$, below which this spectral radius is guaranteed to be less than $1$. Furthermore, we derive a mixed linear-quadratic inequality based upper bound for the optimality gap norm, and provide a rigorous proof of a local asymptotic convergence rate of \(1 - \eta \big(1 - \frac{\gamma}{\mu}\big)\) given the Hessian approximation error $\gamma < \mu$, which formally explains the faster convergence rate of Network-
GIANT. Numerical experiments are carried out with a reduced CovType
dataset for binary logistic regression over a variety of graphs, including heterogeneous data distributions, to illustrate the above theoretical results.
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Audio and Speech Processing
SA-SSL-MOS: Self-supervised Learning MOS Prediction with Spectral Augmentation for Generalized Multi-Rate Speech Assessment
Fengyuan Cao, Xinyu Liang, Fredrik Cumlin et al. (+4 more)
Designing a
speech quality assessment (SQA) system for estimating mean-opinion-score (MOS) of multi-rate
speech with varying sampling frequency (16-48 kHz) is a challenging task. The challenge arises due to the limited availability of a MOS-labeled training
dataset comprising multi-rate
speech samples. While self-supervised learning (SSL) models have been widely adopted in SQA to boost performance, a key limitation is that they are pretrained on 16 kHz
speech and therefore discard high-frequency information present in higher sampling rates. To address this issue, we propose a spectrogram-augmented SSL method that incorporates high-frequency features (up to 48 kHz sampling rate) through a parallel-branch architecture. We further introduce a two-step training scheme: the model is first pre-trained on a large 48 kHz
dataset and then fine-tuned on a smaller multi-rate
dataset. Experimental results show that leveraging high-frequency information overlooked by SSL features is crucial for accurate multi-rate SQA, and that the proposed two-step training substantially improves generalization when multi-rate data is limited.
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All authors Fengyuan Cao, Xinyu Liang, Fredrik Cumlin, Victor Ungureanu, Chandan K. A. Reddy, Christian Schuldt, Saikat Chatterjee
Systems and Control · Cross-listed from cs.MA
ROSA: Roundabout Optimized Speed Advisory with Multi-Agent Trajectory Prediction in Multimodal Traffic
Anna-Lena Schlamp, Jeremias Gerner, Klaus Bogenberger et al. (+2 more)
We present ROSA – Roundabout Optimized Speed Advisory – a system that combines multi-
agent trajectory prediction with coordinated speed guidance for
multimodal, mixed traffic at roundabouts. Using a
Transformer-based model, ROSA jointly predicts the future trajectories of vehicles and Vulnerable Road Users (VRUs) at roundabouts. Trained for single-step prediction and deployed autoregressively, it generates deterministic outputs, enabling actionable speed advisories. Incorporating motion dynamics, the model achieves high accuracy (ADE: 1.29m, FDE: 2.99m at a five-second prediction horizon), surpassing prior work. Adding route intention further improves performance (ADE: 1.10m, FDE: 2.36m), demonstrating the value of connected vehicle data. Based on predicted conflicts with VRUs and circulating vehicles, ROSA provides real-time, proactive speed advisories for approaching and entering the roundabout. Despite prediction uncertainty, ROSA significantly improves vehicle efficiency and safety, with positive effects even on perceived safety from a VRU perspective. The source code of this work is available under: github.com/urbanAIthi/ROSA.
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All authors Anna-Lena Schlamp, Jeremias Gerner, Klaus Bogenberger, Werner Huber, Stefanie Schmidtner
Systems and Control
Hierarchical parameter estimation for distributed networked systems: a dynamic consensus approach
Ariana R. Mendez-Castillo, Rodrigo Aldana-Lopez, Antonio Ramirez-Trevino et al. (+2 more)
This work introduces a novel two-stage distributed framework to globally estimate constant parameters in a networked system, separating shared information from local estimation. The first stage uses dynamic average consensus to aggregate
agents' measurements into surrogates of centralized data. Using these surrogates, the second stage implements a local
estimator to determine the parameters. By designing an appropriate consensus gain, the persistence of excitation of the regressor
matrix is achieved, and thus, exponential convergence of a local Gradient
Estimator (GE) is guaranteed. The framework facilitates its extension to switched network
topologies, quantization, and the heterogeneous substitution of the GE with a Dynamic Regressor Extension and Mixing (DREM)
estimator, which supports relaxed excitation requirements.
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All authors Ariana R. Mendez-Castillo, Rodrigo Aldana-Lopez, Antonio Ramirez-Trevino, Rosario Aragues, David Gomez-Gutierrez
Systems and Control
A Multi-Bound Robust Optimization Approach for Renewable-Based VPP Market Participation Considering Intra-Hourly Uncertainty Exposure
Hadi Nemati, Álvaro Ortega, Enrique Lobato et al. (+1 more)
With the ongoing transition of electricity
markets worldwide from hourly to intra-hourly bidding,
market participants–especially Renewable Energy Sources (RES)–gain improved opportunities to adjust energy and reserve schedules and to benefit from more accurate higher-resolution forecasts. However, this shift requires participants to update decision-making frameworks and to strengthen uncertainty management in order to fully exploit the new
market potential. In particular, Renewable-Based Virtual Power Plants (RVPPs) aggregating dispatchable and non-dispatchable RES must account for these changes through
market-oriented scheduling methods that efficiently address multiple uncertainties, including electricity prices, RES generation, and demand consumption. In this vein, this paper proposes a multi-bound robust optimization framework to simultaneously capture these uncertainties, explicitly incorporate intra-hourly variability, and differentiate the deviation levels (frequent, moderate deviations and rare, extreme ones) of uncertain parameters. The proposed approach yields less conservative and more implementable bidding and scheduling decisions, thus improving RVPP profitability in both energy and reserve
markets. Simulation studies compare the proposed method with standard robust optimization and evaluate the operational,
market-strategy, and economic impacts of quarter-hourly versus hourly
market resolution. Results indicate that the normalized absolute differences, across different uncertainty-handling strategies, between hourly and 15-minute schedules are 18.0–34.2% for day-ahead traded energy, and 28.7–65.6% and 10.1–16.3% for upward and downward reserve traded in the secondary reserve
market, respectively. Furthermore, relative to classic robust optimization, the proposed multi-bound approach increases profit by 24.9–49.2% across the considered strategies.
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All authors Hadi Nemati, Álvaro Ortega, Enrique Lobato, Luis Rouco
Signal Processing · Cross-listed from cs.LG
Parameter-Minimal Neural DE Solvers via Horner Polynomials
T. Matulić and D. Seršić
We propose a parameter-minimal neural architecture for solving differential equations by restricting the hypothesis class to Horner-factorized
polynomials, yielding an implicit, differentiable trial solution with only a small set of learnable coefficients. Initial conditions are enforced exactly by construction by fixing the low-order
polynomial degrees of freedom, so training focuses solely on matching the differential-equation residual at collocation points. To reduce approximation error without abandoning the low-parameter regime, we introduce a piecewise ("spline-like") extension that trains multiple small Horner models on subintervals while enforcing continuity (and first-derivative continuity) at segment boundaries. On illustrative ODE
benchmarks and a heat-equation example, Horner networks with tens (or fewer) parameters accurately match the solution and its derivatives and outperform small MLP and sinusoidal-representation baselines under the same training settings, demonstrating a practical accuracy-parameter trade-off for resource-efficient scientific modeling.
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Systems and Control
DC Microgrids with Nested Nonlinear Distributed Control: Scalable Large-Signal Stability and Voltage Containment
Cornelia Skaga, Mahdieh S. Sadabadi and Gilbert Bergna-Diaz
This paper investigates a cyber-physical DC microgrid employing a nonlinear distributed consensus-based control scheme for coordinated integration and management of distributed generating units within an expandable framework. Relying on nested primary andsecondary control loops; a (distributed) outer-loop and a (decentralized) inner-loop, the controller achieves proportional current sharing among all distributed generation units, while dynamically operating within predefined voltage limits. A rigorous Lyapunov-based stability analysis establishes a scalable global exponential stability certificate under some tuning conditions and sufficient time-scale separation between the control loops, based on singular perturbation theory. An optimization-based tuning strategy is then formulated to identify and subsequently diminish unstable operating conditions. In turn, various practical tuning strategies are introduced to provide stable operations while facilitating near-optimal proportional current sharing. The effectiveness of the proposed control framework and tuning approaches are finally supported through time-domain simulations of a case-specific low-voltage DC microgrid.
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