Systems and Control
Differentiable Optimization Layered Safety-Critical Control for Risk-Aware Navigation via Conformal Prediction
Jinyang Dong, Shizhen Wu and Yongchun Fang
Risk-aware
navigation in unknown environments is a fundamental challenge for autonomous vehicles operating in complex urban systems. To address this issue, this paper presents a differentiable optimization layered safety-critical control method based on conformal prediction. First, to handle uncertainties arising from sensor noise, the conformal prediction method is employed to generate risk-aware obstacle ellipsoids around an elliptical-shaped
robot. Second, two nested differentiable optimization layers are introduced to build the control barrier functions for obstacle avoidance and feasibility guarantee, respectively. Then, a quadratic program based safety-critical control law is proposed to integrate the above control barrier function constraints as well as input constraints. In the end, the effectiveness of the proposed framework is demonstrated through numerical simulations.
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Signal Processing · Cross-listed from q-bio.QM
A Machine Learning Framework for EEG-Based Prediction of Treatment Efficacy in Chronic Neck Pain
Xiru Wang, Aiden Li, Hongzhao Tan et al. (+3 more)
Chronic neck pain is a leading cause of disability worldwide, and current treatment selection remains largely trial and error. We present a machine learning framework that uses electroencephalography to predict treatment efficacy in patients with chronic neck pain, with the goal of supporting individualized therapy and reducing the burden on healthcare systems. The framework centers on a rigorous data preprocessing stage tailored to the characteristics of each
EEG recording type. For resting-state
EEG, the preprocessing pipeline comprises baseline signal removal, bad channel identification and exclusion, re-referencing, bandpass and notch filtering, Independent Component Analysis, and power spectral density analysis. For motor execution and motor imagery recordings, the same initial steps are applied, after which signals are aligned to trigger events so that event-related desynchronization (ERD) and event-related synchronization (ERS) can be quantified. Synchronously recorded electromyography data are bandpass filtered and smoothed with a moving average, then correlated with the corresponding
EEG channels to characterize the
EEG EMG relationship during attempted movement. In parallel, we performed an extensive literature review of machine learning models applied to clinical
EEG (763 records initially screened, 16 patient and 47 healthy-control studies retained), to inform the post-processing strategy. Through this combined preprocessing and review effort, we aim to develop a robust predictive model that can support personalized healthcare strategies in chronic pain management.
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All authors Xiru Wang, Aiden Li, Hongzhao Tan, Stevie Foglia, Aimee Nelson, Zhen Gao
Signal Processing
Domain-Adaptive Arrhythmia Classification Using a Hybrid Transformer on Wearable Heart Signals
Maedeh H. Toosi and Siamak Mohammadi
Cardiovascular disease remains the leading cause of death globally, underscoring the need for effective, accessible monitoring solutions, particularly through wearable devices that enable continuous, real-time tracking of heart rhythms in home settings. However, deploying deep learning models trained on clinical electrocardiogram (ECG)
datasets to wearable devices remains challenging, as differences in recording equipment, signal quality, and patient populations introduce domain shifts that degrade model performance. We propose a hybrid
transformer model that processes continuous ECG signals alongside seven heart rate variability (HRV) features, where the raw signal path captures beat-level morphological patterns and the HRV path encodes rhythm regularity statistics, allowing the model to jointly leverage complementary information from both representations. To enhance the model's ability to generalize across domains, we employ representation learning techniques, including Maximum Mean Discrepancy (MMD), a non-parametric kernel-based metric that quantifies the distance between feature distributions of different domains, to align feature distributions between source and target domains, addressing the challenge of domain shifts between public
datasets and wearable device data. By leveraging five public ECG
datasets for training, the model learns robust, generalized representations that mitigate domain-specific biases. When tested on wearable device data with an unseen domain, the model achieved an F1-macro 95% and balanced accuracy of 96.15%. These results demonstrate minimal performance degradation, with only a 2% drop in F1-macro compared to seen-domain evaluation, highlighting the model's generalization capabilities and its potential for reliable, real-time heart monitoring applications in home and ambulatory settings.
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Audio and Speech Processing · Cross-listed from cs.SD
ShipEcho – An Interactive Tool for Global Mapping of Underwater Radiated Noise from Vessels
Mark Shipton, Valentino Denona, {\DJ}ula Na{\dj} et al. (+1 more)
Underwater radiated noise from vessels (V-URN) is a recognized environmental stressor that negatively impacts marine ecosystems. Significant resources are invested in the development of V-URN monitoring indicators, regulatory frameworks, and management-oriented assessments. One approach with high potential for impact is V-URN mapping, which can provide actionable spatiotemporal information for environmental assessment and mitigation planning. Producing management-scale maps remains challenging as passive acoustic measurements are spatially sparse and many operational systems depend on specialist workflows and costly access to wide-area vessel activity data. To address these constraints, we introduce ShipEcho, a freely accessible web-based Geographic Information System (GIS) that provides near-real-time V-URN mapping using vessel data acquired through a community-based AIS exchange. Using established vessel SL models and propagation modeling informed by bathymetric data, ShipEcho produces near-real-time and cumulative noise maps across regions worldwide. These include sound pressure levels and sound exposure levels using standard indicators, including the 63~Hz and 125~Hz one-third octave bands and a 20–2000~Hz broadband level. We describe the system architecture, data pipeline, modeling workflow, and key assumptions, and evaluate map accuracy through comparison with acoustic recordings. We then demonstrate how ShipEcho can support management-level assessment, decision-making, and policy initiatives through practical use cases.
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All authors Mark Shipton, Valentino Denona, {\DJ}ula Na{\dj}, Roee Diamant
Systems and Control · Cross-listed from cs.LG
Synergistic Simplex: Cooperative Runtime Assurance for Safety-Critical Autonomous Systems
Ayoosh Bansal, Mikael Yeghiazaryan, Artyom Khachatryan et al. (+4 more)
Autonomous systems increasingly rely on machine-learning (ML) components for safety-critical tasks such as perception and control in autonomous vehicles (AVs). While ML enables essential capabilities, it inevitably exhibits long-tail faults that make it unsuitable for safety-critical tasks. Runtime assurance (RTA) mitigates this issue by pairing ML components with verifiable safety monitors, e.g., Control Simplex and Perception Simplex architectures. However, the limited performance of safety monitors remains a major bottleneck. The Synergistic Simplex (SS) architecture improves system performance by enabling bidirectional integration between ML components and safety monitors while preserving formal safety guarantees. The key innovation here is allowing safety monitors to use ML outputs, which is typically prohibited in RTA systems. We formally derive conditions under which this integration preserves safety and demonstrate the performance benefits. We present the design, analysis, and evaluation of SS for AV obstacle detection.
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All authors Ayoosh Bansal, Mikael Yeghiazaryan, Artyom Khachatryan, Tianyi Zhu, Hunmin Kim, Naira Hovakimyan, Lui Sha
Audio and Speech Processing
DiffVQE: Hybrid Diffusion Voice Quality Enhancement Under Acoustic Echo and Noise
Haljan Lugo, Ernst Seidel, Pejman Mowlaee et al. (+2 more)
Acoustic echo and background noise pose challenges on
speech enhancement in hands-free systems and speakerphones. Discriminatively trained end-to-end methods represent a powerful solution for joint acoustic echo control (AEC) and denoising. However, with the advent of generative methods,
diffusion-based approaches have seen remarkable performance in
speech enhancement tasks. In this work, to the best of our knowledge, we provide the first (still non-causal)
diffusion-based AEC model (DiffVQE) that is reproducible in terms of
topology, training data, and training framework. So far, without employing
diffusion, Microsoft's discriminative DeepVQE model has been shown to excel any of the ICASSP 2023 AEC Challenge entries achieving remarkable performance. Using data from the Interspeech 2025 URGENT Challenge for a diverse, high-quality training
dataset, our DiffVQE excels DeepVQE both in echo and noise control performance, as well as in computational complexity and model size.
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All authors Haljan Lugo, Ernst Seidel, Pejman Mowlaee, Ziyue Zhao, Tim Fingscheidt
Signal Processing
Towards Interpretable Damage Detection based on Aerodynamic Pressure Measurements
Philip Franz, Max von Danwitz, Gregory Duthé et al. (+2 more)
The increasing flexibility of modern large wind turbine blades necessitates cost-efficient and reliable structural monitoring solutions. For this purpose, we propose to use aerodynamic pressure measurements obtained via Aerosense, a novel, non-intrusive and economical sensing system. In former work [Franz et al., 2025], we investigated the potential of aerodynamic pressure measurements for structural damage detection on elastic and aerodynamically loaded structures. An experimental campaign was conducted on a NACA 633418 airfoil mounted on a vertically vibrating cantilever beam within an open wind tunnel. Structural damage was introduced progressively through controlled saw cuts near the beam support. Aerodynamic pressure distributions were recorded under varying inflow conditions and structural states. Based on this data set, we developed a convolutional neural network to detect structural damage and classify its severity using only aerodynamic pressure signals. The results demonstrate that pressure measurements can effectively enable real-time detection and quantification of damage in elastic, beam-like structures subjected to mildly turbulent flow and varying operational conditions. Recognizing the limitations of pure black-box classification, in this study, we further incorporate physics-based insights and explainable machine learning methods to interpret how structural damage influences both the dynamic response and the aerodynamic pressure field. This leads to an enhanced damage detection pipeline, aiming to improve transparency, robustness, and physical consistency in data-driven monitoring of elastic, aerodynamically loaded structures.
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All authors Philip Franz, Max von Danwitz, Gregory Duthé, Alexander Popp, Eleni Chatzi
Audio and Speech Processing
Rethinking Entropy Minimization in Test-Time Adaptation for Autoregressive Models
Wei-Ping Huang, Chee-En Yu, Guan-Ting Lin et al. (+1 more)
Test-Time Adaptation (TTA) via
entropy minimization (EM) has proven effective for classification tasks, yet its application to generative autoregressive models remains theoretically fragmented. Existing approaches typically rely on distinct heuristics, such as teacher forcing with pseudo labels or policy-gradient-based reinforcement learning, without a unified mathematical foundation. In this work, we resolve this discrepancy by deriving a rigorous formulation of EM tailored to autoregressive models. We show that the exact objective naturally decomposes into a
token-level policy gradient loss and a
token-level
entropy loss, and we reinterpret prior methods as partial realizations of this unified formulation. Using Whisper ASR as a testbed, we demonstrate that our approach consistently improves performance across more than 20 diverse domains, including acoustic noise, accents, and
multilingual settings.
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All authors Wei-Ping Huang, Chee-En Yu, Guan-Ting Lin, Hung-yi Lee
Signal Processing
Improving TMS EEG Signal Quality for Closed-Loop Neuro Stimulation via Source-Domain Denoising
Zhen Tang, Ameer Hamoodi, Stevie Foglia et al. (+2 more)
This research addresses a validated TMS
EEG cleaning pipeline and a corresponding
benchmark dataset. It evaluates two widely used artifact removal pipelines. A reference
dataset of carefully preprocessed
EEG signals was established to support future
algorithm development and enable systematic comparison of automated artifact removal strategies, despite the absence of a true physiological ground truth. The study evaluates the effectiveness of two widely used source based artifact removal approaches and examines their impact on signal quality improvement and preservation of TMS-evoked potentials. The results support the robustness of the proposed preprocessing workflow and demonstrate its potential for improving data reliability in both research and clinical applications. A key goal is integrating TMS
EEG and
embedding it within a larger BCI framework. Ultimately, these efforts aim to enhance understanding of cortical dynamics and expand the clinical and research applications of TMS
EEG.
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All authors Zhen Tang, Ameer Hamoodi, Stevie Foglia, Aimee Nelson, Zhen Gao
Signal Processing · Cross-listed from cs.IT
Information Density as a Quantitative Measure for AI-enabled Virtual Sensing: Feasibility and Limits
Hrishikesh Dutta, Roberto Minerva, Reza Farahbakhsh et al. (+1 more)
Modern IoT and sensor networks generate vast amounts of data, posing significant challenges for storage, transmission, and real-time processing. Traditional approaches, such as compressive sensing and machine learning-based compression, often suffer from computational inefficiencies and irreversible data loss. This paper introduces Information Density as a quantitative metric to support sensor deployment and enable AI-driven virtual sensing. We propose a framework that leverages spatial, temporal and inter-modal correlations among sensor signals to perform sensing tasks even in the absence of physical sensors. Two complementary measures: (i) Phase in Eigen Space and (ii) Mutual Information, are developed to quantify and assess information density, enabling the selection of optimal sensor configurations across both intra-modality and cross-modality scenarios. Validated using real-world data from Madrid's smart city infrastructure, this framework demonstrates the feasibility of replacing physical sensors with virtual ones under bounded error conditions (e.g., achieving $<3.21\%$ mean error with a single sensor). The results highlight the potential for scalable and energy-efficient sensing systems in smart environments.
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All authors Hrishikesh Dutta, Roberto Minerva, Reza Farahbakhsh, Noel Crespi
Signal Processing
Neural Posterior Estimation of Terrain Parameters from Radar Sounder Data
Jordy Dal Corso, Annalena Kofler, Marco Cortellazzi et al. (+2 more)
Radar sounders are electromagnetic instruments that can probe deep into the subsurface of Earth and other planetary bodies by processing the echo of transmitted radar waves. Conventional approaches for analyzing such data rely on approximate assumptions and often produce point estimates that ignore parameter correlations as well as
galactic and measurement noise. We propose a simulation-based inference approach to terrain parameter inversion from radar sounder data, where synthetic observations from a GPU-based simulator are used to train a neural network-based density
estimator for neural posterior estimation (NPE). By explicitly conditioning on reference surface assumptions, the proposed framework allows systematic evaluation of posterior robustness to reference surface variability. We demonstrate that our NPE model is well calibrated on simulated data and transferable to real Mars radar profiles, where we analyze terrain parameters using literature-informed reference values.
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All authors Jordy Dal Corso, Annalena Kofler, Marco Cortellazzi, Lorenzo Bruzzone, Bernhard Schölkopf
Image and Video Processing
Multimodal synthesis of MRI and tabular data with diffusion in a joint latent space via cross-attention
Daniel Mensing, Jan Kapar, Jochen G. Hirsch et al. (+3 more)
We propose a
multimodal latent
diffusion model that jointly synthesizes volumetric
magnetic resonance imaging (MRI) and tabular clinical data within a shared latent space via cross-
attention. This approach enables coherent joint representation learning of MRI and tabular modalities for generative modeling. Our model utilizes a variational autoencoder to fuse the two modalities before
diffusion-based synthesis, allowing modality-appropriate reconstruction with separate decoders for MRI and tabular data. We evaluated the framework on data from the German National Cohort (NAKO Gesundheitsstudie), comprising over 10,000 participants with MRI scans and clinical tabular features such as age, sex, body measurements, and ethnicity. The generated MRI volumes exhibited anatomical plausibility and body composition consistent with the synthesized tabular attributes. Quantitative evaluation using Fréchet distance and precision-recall metrics confirmed high-fidelity image generation. In the tabular modality, our model outperformed CTGAN across standard evaluation metrics and achieved results comparable to TVAE, demonstrating competitive performance relative to established unimodal baselines. This work is, to our knowledge, the first to demonstrate the feasibility of jointly modeling MRI and mixed-type tabular data in a single latent
diffusion framework, offering a proof-of-concept for generating coherent synthetic
multimodal patient data and aligning with the broader goal of developing digital twins in healthcare.
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All authors Daniel Mensing, Jan Kapar, Jochen G. Hirsch, Matthias Günther, Horst Hahn, Marvin N. Wright
Signal Processing
Large Gain Degradation of Reflective Intelligent Surfaces in Realistic Environments
Dmitry Chizhik and Jinfeng Du
Reflective Intelligent Surfaces (RIS) are considered promising in improving coverage in Non-Line of Sight (NLOS) wireless links, especially at mm wave or higher frequency bands. Coverage provided by RIS is here compared to coverage from such ambient propagation mechanisms as scattering from street poles (e.g. lampposts), and corner diffraction. A simple formula for RIS gain degradation due to channel angle spread is derived. It is found an ideal 0.3 m x 0.3 m RIS at 28 GHz promises to deliver only about 5 dB more power at 200 m around an urban street corner than the ambient scatter already there. Consideration of angle spread brings about some 14 dB drop in RIS power, bringing it well below ambient mechanisms. A 1 m x 1 m RIS at 28 GHz, offers under 2 dB advantage over ambient scatter after including the 25 dB gain degradation due to angle spread. This raises questions about usefulness of RIS-assisted coverage extension in realistic environments.
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Systems and Control
Adaptive Diagonal Loading for Norm Constrained Beamforming
Manan Mittal, Ryan M. Corey, John R. Buck et al. (+1 more)
Reliable adaptive beamforming is critical for large microphone arrays operating in highly dynamic acoustic environments. In scenarios characterized by fast-moving talkers and interferers, the available sample support for estimating the spatial correlation
matrix is often snapshot-deficient. This deficiency, coupled with array imperfections, degrades the White Noise Gain (WNG), leading to severe target signal cancellation. To ensure stable and robust beamforming, we propose a novel adaptive diagonal loading method that guarantees the WNG remains strictly within specified bounds. By leveraging the Kantorovich inequality, we map the desired WNG to a strict upper bound on the condition number of the correlation
matrix. Furthermore, we present three estimation techniques for the adaptive loading level, ranging from trace-based bounding to exact
eigenvalue decomposition, offering scalable computational complexities of $\mathcal{O}(M)$, $\mathcal{O}(M^2)$, and $\mathcal{O}(M^3)$. Our approach demonstrates highly stable beamforming under fast-changing interference.
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All authors Manan Mittal, Ryan M. Corey, John R. Buck, Andrew C. Singer