Signal Processing · Cross-listed from cs.LG
Structured Reinforcement Learning for Bayesian Persuasion : Application to Intelligent Interactive Driving
Merlin Paul and Anup Aprem
Interactive driving, wherein an intelligent lead vehicle equipped with real-time traffic data coordinates route choices of connected vehicles, offers a promising approach to dynamic traffic management. To address the challenge of harmonising decisions, this paper considers the strategic information revealing framework of
Bayesian persuasion. Here, the principal (lead vehicle) aims to guide the
agent's (connected vehicle) partially observable sequential decision making towards its own objectives by selectively revealing information, such as real-time traffic ahead, using signals. However, the
agent's farsighted response to maximize its long-term reward, renders the principal's signaling strategy design computationally challenging. We propose an online structured reinforcement learning framework to synthesize computationally efficient signaling strategy which is persuasive for a far-sighted
agent. The main contributions of the paper are as follows: (i) For a monotonic
agent with approximate best response, we propose MAPL, a structured policy learning
algorithm for faster online learning, (ii) Identification of sufficient conditions for the supermodular structure of the Q function of the principal for a monotonic
agent, (iii) Identification of sufficient conditions to ensure the persuasiveness of the principal's signaling strategy, (iv) Supermodular Q learning for Principal (SQP), which leverages the supermodular structure of principal's action value to synthesize computationally efficient signaling strategy that is persuasive for a monotonic learning
agent, (v) Numerical analysis considering a real-time application of
Bayesian persuasive driving for lane selection demonstrates that the proposed method is 30% cost efficient for optimising travelling rewards of both the lead and connected vehicle compared to the existing methodologies for signaling strategy design.
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Audio and Speech Processing
Cover First, Disagree Softly: Rethinking Mismatch-First Active Learning for Frame-Level Audio Classification
Shiqi Zhang and Tuomas Virtanen
Sound event detection relies on frame-level strong labels whose annotation is expensive. Active learning addresses this problem by selecting the audio segments whose labels help the classifier most. One of the prevailing acquisition strategies for this task, mismatch-first farthest-traversal (MFFT), combines the disagreement between two classifiers and the diversity of the selected segments through hard sequential decisions. It selects whole groups of high-disagreement segments first and spreads only the remaining budget by farthest traversal. On two multi-label
datasets we show that this design is blind to the similarity among the selected segments and fails under low budgets, with every mismatch-first variant ending below the plain
geometric strategy it builds on. We propose mismatch-weighted facility location (MW-FL), which spends the entire budget through a disagreement-weighted coverage objective that penalizes similarity among the selected segments. The disagreement signal from MFFT is used to obtain the nonnegative weights of this facility-location objective, using fixed smoothing without
dataset-specific tuning. Experiments across two
geometric mechanisms with three ways of using disagreement show that coverage of the selected segments is the dominant factor, hard disagreement gating of selection is harmful on both mechanisms, and soft disagreement weighting helps on top of coverage. MW-FL attains the best area under the learning curve on both
datasets.
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Audio and Speech Processing
Greedy Volume Maximization of Gradient Embeddings for Long-Tailed Frame-Level Bioacoustic Active Learning
Shiqi Zhang, Marius Faiß, Ariana Strandburg-Peshkin et al. (+1 more)
Bioacoustic call-type classification relies on costly expert annotation. Active learning can reduce this burden by selecting a small batch of segments for expert annotation and using the labeled segments for training the classifier. The setting is hard: the target calls are extremely sparse and the call-type distribution is long-tailed, so a tight budget must be spent on the few rare, informative segments. We propose BADGE-Greedy-DPP, a deterministic batch selector that greedily adds the segment whose BADGE gradient
embedding most enlarges the volume spanned by the batch; because this log-volume objective is submodular, the greedy rule guarantees a batch value at least a (1-1/e) fraction of the optimum of this objective, a guarantee not provided by BADGE's existing k-means++ and MCMC DPP sampling heuristics. There is also a temporal granularity mismatch in the task. The acquisition function scores whole segments, yet the informative frames inside them are few. Uniform averaging therefore washes them out. The BADGE construction naturally addresses this mismatch when applied frame-wise, as prediction residuals weight the aggregated pseudo-gradient, so confidently predicted no-call frames contribute little while a single uncertain rare-call frame can still set the segment's direction. Across 10 runs on a sparse, imbalanced hyena call-type
dataset, BADGE-Greedy-DPP achieves the best overall and rare-call-type performance among all compared query strategies, including MFFT, the strongest non-BADGE baseline, and the two vanilla BADGE traversals.
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All authors Shiqi Zhang, Marius Faiß, Ariana Strandburg-Peshkin, Tuomas Virtanen
Systems and Control · Cross-listed from cs.RO
Flow-aware Optimal Navigation in Unsteady Flows through Reinforcement Learning
Andrea Maria Braghin, Nicolò Botteghi, Matteo Tomasetto et al. (+2 more)
Autonomous robotic
navigation in nonstationary time-varying fluid flows remains a fundamental challenge due to partial observability and the unpredictability of realistic environments. While classical optimal control frameworks employed in robotics require unrealistic a-priori global flow knowledge, biological systems are able to navigate successfully by exploiting localized sensory cues. In this work we present a reinforcement learning approach using the TD3
algorithm to train autonomous
agents to reach arbitrary targets within a parametric, chaotic double-gyre flow. To investigate optimal sensory mechanisms, we evaluate five bio-inspired observation strategies based on relative position, local velocity or local vorticity measures, and short-term
memory variants. Additionally, we analyze the impact of providing
agents with explicit global flow parameters. Numerical results demonstrate that an
agent that is able to sense and remember a set number of flow velocity measures achieves the highest performance. The experiments reveal a trade-off in sensor utility: velocity-aware
agents optimize energy efficiency, whereas vorticity sensors provide superior structural mapping and achieve better target proximity. Incorporating explicit global flow parameters is shown to decrease
navigation performance. This behavior suggests that reinforcement learning-based autonomous systems develop more robust and general policies when restricted to implicit flow representations. The presented results offer insights for improving the transition of bio-inspired robotic
navigation from simulation to real-world environments.
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All authors Andrea Maria Braghin, Nicolò Botteghi, Matteo Tomasetto, Andrea Manzoni, Gabriele Cazzulani
Systems and Control
Transformer is All You Need: Attention-Based Anomaly Detection and Classification in Inverter-Rich Power Systems
Emad Abukhousa, Saman Zonouz and A.P. Sakis Meliopoulos
Inverter-based resources and IEC 61850 process-bus measurements introduce new protection challenges, including nontraditional fault behavior and measurement-domain cyber-physical attacks. This paper evaluates DL-Xformer, an
attention-based
Transformer classifier for multi-class fault and cyberattack diagnosis, side-by-side with Dynamic State Estimation-Based Protection (DSE-EBP) on identical high-fidelity electromagnetic-transient (EMT) streaming measurements from an IBR-rich power grid. The evaluation uses an 18-class taxonomy covering normal operation, 11 physical faults, and six measurement-domain attacks, including CT/PT ratio manipulation and GPS spoofing, sampled at 4.8 kHz from synchronized upstream and downstream merging units. DSE-EBP detects all streaming anomalies in 0.417-1.660 ms, with a mean detection time of 0.756 ms, while DL-Xformer classifies the same events in 2.50-50.42 ms, with a mean classification time of 13.46 ms. The longest delay occurs in a deliberate stress case where a CT ratio attack is introduced while residual oscillations from a preceding DLG fault have not fully settled; the event-window accuracy drops to 76.1 %, but the stable final classification remains correct. Measurement-level feature attribution shows that the DL-Xformer decision is driven by physically meaningful current and voltage channels at the attacked measurement location. Together, the two methods motivate a layered protection architecture for next-generation inverter-dominated smart grids.
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Signal Processing
Channel Parameter Estimation and Characteristic Analysis at THz Bands in Hybrid Near-Field/Far-Field Scenarios
Hengtai Chang, Cheng-Xiang Wang, Cunhua Pan et al. (+4 more)
The terahertz (THz) band is a promising candidate for high-data-rate transmission in future wireless communication systems, where large-scale
antenna arrays are deployed to combat the severe propagation loss. In such configurations, near-field and far-field multipath components (MPCs) coexist in the channel, which challenges conventional parameter estimation methods. This paper presents a 260–380 GHz virtual uniform linear array (ULA) measurement campaign in an indoor scenario, and proposes a hybrid-field space-alternating generalized expectation-maximization (SAGE)
algorithm that discriminatively estimates near-field and far-field MPCs via a visible region (VR)-aided weighted wideband
Bayesian phase-
curvature classification, while tracking spatial birth-death phenomena through VR estimation. Simulations with known ground truth validate the effectiveness of the proposed classifier and the hybrid wavefront modeling. Measurement-based characterization reveals that near-field MPCs account for over 90% of total MPCs at a 2 m distance, the scatterer distances and invisible region lengths follow lognormal and exponential distributions, respectively, and spatial non-stationarity intensifies with increasing frequency and decreasing distance. These findings provide quantitative guidelines for THz channel modeling and system design.
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All authors Hengtai Chang, Cheng-Xiang Wang, Cunhua Pan, Jian Sun, Bingchang Hua, Yongchao He, el-Hadi M. Aggoune
Systems and Control · Cross-listed from cs.LO
Ripple: An Open, AI-Formalized Lean 4 Framework for Computing with CRNs
Ho-Lin Chen and Xiang Huang
We present Ripple, an open, AI-formalized Lean 4 framework for the mathematics of computing with chemical reaction networks (CRNs) – one extensible, machine-checked development that gathers several strands of the field into a single setting, and is built to grow. It formalizes: the theory of which real numbers a CRN can compute – a single Lean definition of real-time CRN computation, the class of reals it captures, and the compilation pipeline (a GPAC /
polynomial-ODE layer, a dual-rail compiler, and four stages down to large-population protocols) that realizes them, built so that adding a new number is a plug-in; three landmark population-protocol majority
algorithms – approximate, exact, and self-stabilizing exact majority; the
stochastic-to-deterministic bridge, through three machine-checked versions of Kurtz's mean-field
theorem; and two classical Turing-completeness results – Bournez–Graca–Pouly for the deterministic GPAC and Soloveichik–Cook–Winfree–Bruck for
stochastic CRNs. Each of these is verified to depend on exactly the three Mathlib foundational axioms, with no sorry. Along the way the formalization repaired genuine, previously unnoticed gaps in published proofs – a compilation step that can transiently leave the unit interval, and an algebraic-number construction that silently rests on Catalan's
conjecture – and surfaced a sharp open problem about when a holonomic series admits an exact, rational-data
polynomial-ODE encoding. The whole development is open and every proof is kernel-checked, so the results can be independently re-verified; and because it was written predominantly by AI
agents using only publicly available models, the workflow that produced it can be reproduced with the same public toolchain.
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Systems and Control
Non-asymptotic Bounds of Learning-based Linear MPC With Input Constraints and Unbounded Stochastic Noise
Changyi Lei, Seth Siriya, Dragan Nešić et al. (+1 more)
This paper studies learning-based model predictive control (MPC) for stabilizing unknown discrete-time linear systems with hard input constraints and additive unbounded sub-Gaussian disturbances. We adopt a certainty-equivalence (CE) design that combines a switching MPC control law with online regularized least-squares (RLS) parameter estimation. The resulting switching control law blends the MPC with a saturated deadbeat controller, ensuring global closed-loop stability. Building upon non-asymptotic error bound of least-squares, we derive non-asymptotic, high-probability stability bounds for the closed-loop system under the proposed switching controller. Numerical experiments illustrate and support the theoretical findings.
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All authors Changyi Lei, Seth Siriya, Dragan Nešić, Ye Pu
Signal Processing
Pinching-Antenna Systems (PASS)-Based User-Side Navigation: An Anchor-Line-based Approach
Zongyi Li, Jun Wang, Tianwei Hou et al. (+1 more)
Pinching-
antenna systems (PASS) are capable of dynamically reconfiguring wireless channels by flexibly repositioning pinching
antennas (PAs) along the waveguides to establish short-range line-of-sight links. In this paper, a user-side
navigation framework for PASS is proposed, where mobile users determine their own positions using only downlink broadcast signals without any prior knowledge of the PA positions. First, a Lambert W function-based PA positioning and pseudorange estimation (LWF-PAP)
algorithm is developed, in which the closed-form expressions for both the PA positions along the waveguide and the PA-user pseudoranges are derived. Second, a weighted least squares-based PASS
navigation (WLS-PAN)
algorithm is formulated, where the nonlinear PASS-based
navigation equations are transformed into a closed-form linear system, and the optimal weight
matrix is derived, achieving minimum-variance unbiased estimation. Third, the PA-derived position dilution of precision (PA-PDOP) metric is further defined to characterize the theoretical accuracy bound. Simulation results demonstrate that centimeter-level positioning accuracy is achieved for both PAs and users within the breakpoint distance. It is also shown that uniform PA deployment and a moderate increase in the number of PAs effectively improve
navigation accuracy, thereby validating the effectiveness and robustness of the proposed framework for distributed real-time user-side self-
navigation.
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All authors Zongyi Li, Jun Wang, Tianwei Hou, Anna Li
Audio and Speech Processing · Cross-listed from cs.SD
Auditing Protocol-Level Shortcuts in Large Audio Language Model Judges for Speech Evaluation
Joonyong Park, David M. Chan, Yuki Saito et al. (+1 more)
Large audio-
language models (LALMs) are increasingly used as automatic judges for
speech evaluation. However, high agreement with human ratings does not guarantee that their verdicts are grounded in the audio. A judge may instead rely on specialist labels or reference data supplied by the evaluation protocol itself, taking a shortcut in place of listening to the audio. In this paper, we audit such protocol-level “shortcuts” in LALM judges across three common deployment protocols: feature-blueprint judging, where the audio is replaced by a structured text description of acoustic features, reference-conditioned judging, and pairwise A/B comparison. Across six judges and four attributes, we find that several LALMs rely on protocol-level shortcuts. For example, in feature-blueprint judging, incorrect specialist labels reduce five judges'
emotion accuracy to 0.10 or below, and in concatenated A/B comparisons, Qwen3-Omni-Thinking often picks the same slot regardless of order swaps. These results indicate that aggregate agreement can overstate the validity of LALM judges unless the model and the evaluation protocol are assessed jointly, and that each model-protocol pair should be evaluated with a matched shortcut probe.
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All authors Joonyong Park, David M. Chan, Yuki Saito, Hiroshi Saruwatari
Audio and Speech Processing · Cross-listed from cs.CV
Bring Music The Horizon: Music-Driven 360$^\circ$ Video Generation
Kai Hsu Tsai, Yong Wei Fu, Hung I Yang et al. (+1 more)
Music visualization offers a powerful way to enhance listeners' understanding and experience of music by translating auditory signals into visual forms. However, most existing approaches either rely heavily on lyrics or generate flat, non-immersive
videos similar to conventional music
videos, which limits their ability to convey the emotional dynamics of music and provide an immersive listening experience. We propose Bring Music The Horizon, an
emotion-aware pipeline for music-driven 360$^\circ$
video generation. Given an input song, our work first estimates its emotional trajectory by predicting valence-arousal values at the level of every four bars. These values are then converted into
emotion-aware visual guidance using EmotiCrafter, and these guidance vectors can be manipulated by the SEGA framework, which provides fine-grained semantic control for keyframe generation. Finally, image-to-
video models are applied to the generated keyframes to synthesize temporally continuous 360$^\circ$
videos for immersive music visualization. Our pipeline generates 360$^\circ$ music visualization
videos that reflect the emotional progression and temporal structure of the input song. We demonstrate its capability using songs from different genres and provide qualitative comparisons with From-Sound-To-Sight, a representative audio-to-visual generation baseline, on our project page at https://etoile-et-toi-mp3.github.io/BMTH_Project_Page/.
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All authors Kai Hsu Tsai, Yong Wei Fu, Hung I Yang, Yu-Chih Chen
Signal Processing
Posterior-Confidence Driven Beamforming for Energy-Efficient Integrated Sensing and Communication
Nusaibah A. Alshorman and Huseyin Arslan
Energy efficiency will pose an essential limitation for sixth-generation (6G) integrated sensing and communication (
ISAC) systems, given the high sensing power consumption associated with persistent sensing, despite stable communication requirements. This paper proposes an energy-efficient multiple-input multiple-output (
MIMO) dual-functional radar-communication (DFRC) beamforming framework that minimizes transmit power while guaranteeing per-user signal-to-interference-plus-noise ratio (SINR) and reliable multi-target tracking. The key innovation is a tracking-aware, skip-enabled sensing policy that departs from the conventional always-on probing paradigm. Instead of enforcing sensing at every epoch, sensing is selectively triggered according to two complementary statistics derived from an extended Kalman filter (EKF): a posterior confidence metric and the normalized innovation squared (NIS). While the former ensures accurate estimation, the latter guarantees reliable measurements, and thus sensing can only be activated when additional information is required. To ensure robustness under intermittent sensing, sector-based beampattern constraints are combined with a nonzero safety illumination floor imposed to guarantee reliable target tracking when skipping occurs. Numerical results show that the proposed framework achieves a significant reduction in transmit power compared to other baselines, without any deterioration in the communication system's performance or excessive impact on the sensing process.
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Signal Processing
Compositional Zero-Shot Recognition based on Tangent Space Disentanglement for Composite Modulation Signals
Yurui Zhao, Xiang Wang, Zhitao Huang et al. (+1 more)
Automatic composite modulation recognition (ACMR) is critical for integrated sensing and communication (
ISAC) systems, while conventional approaches face significant challenges due to the semantic coupling between inner-layer and outer-layer modulations in composite modulation (CM), degraded performance under joint hardware and channel imperfections, and limited capability to handle unknown modulation schemes. To this end, we design a disentangled semantic space and propose zero-shot learning framework. Within this framework, a logarithmic projection first linearizes the multiplicative coupling between modulation layers and a learnable
geometric transformation is used for layer-wise semantic features. We instantiate the framework as the Tangent Space Disentanglement Network (TSDN). TSDN integrates logarithmic mapping, a spatial
transformer network for learning the
geometric transformation, and a multi-objective loss function that balances discrimination with cross-domain generalization. Comprehensive experiments demonstrate that TSDN achieves over 93% zero-shot recognition accuracy, outperforms unified-semantic and multi-task baselines by significant margins, and maintains robust performance under combined channel fading and hardware imperfections down to 4 dB SNR.
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All authors Yurui Zhao, Xiang Wang, Zhitao Huang, Baoguo Li
Systems and Control
Machine Learning Challenges in Intelligent Unmanned Aerial Vehicle Operations in Developing Economie
Isuru Munasinghe, Nethmi Pathirana, Charitha Dombawala et al. (+2 more)
Unmanned aerial vehicle (
UAV) environments present significant challenges for machine learning (ML) due to limited platform resources, heterogeneous sensor data, dynamic mission conditions, and safety-critical requirements. This paper examines these constraints across the core functional areas of
UAV intelligence, including
navigation, perception, communication-aware operation, and resilience specifically in the context of developing economies. In such settings, these challenges are often amplified by constraints such as cost sensitivity, limited infrastructure, intermittent connectivity, regulatory uncertainty, and harsh or variable operating environments. The discussion highlights the gap between ML performance in controlled experimental backgrounds and dependable deployment in real-world
UAV missions within developing economies context.
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All authors Isuru Munasinghe, Nethmi Pathirana, Charitha Dombawala, Asanka Perera, Akila Pemasiri
Systems and Control · Cross-listed from cs.RO
Stress-Sharing for Decentralized Fault Repair in Modular Spacecraft
Sidhdharth D. Sikka, Yue Shen and Shaoshuai Mou
Structural damage in modular spacecraft can disrupt mechanical and communication connectivity, reducing system capability. Existing approaches rely on redundancy or preplanned reconfiguration and do not enable autonomous repair under local information and physical constraints. We model the spacecraft as a
lattice-constrained graph and introduce a fully decentralized, asynchronous stress-sharing repair policy inspired by biological wound healing: local distress signals guide surviving modules toward damaged regions to close fragmented gaps, after which each displaced module locally retraces its own motions to recover the pre-damage shape, using only local information and no absolute position sensing. We evaluate the policy in PyBullet rigid-body simulation across structures of up to 160 modules, three fault densities (10, 20, 30%), and random and localized damage. The policy consolidates the surviving modules into a single connected body: even in the most severe case tested, where 30% of modules fail at random, it gathers roughly 80% or more of the surviving modules into one connected component, and this fraction improves with assembly size, making the approach well suited as a swarm-scale repair policy for large modular spacecraft.
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Systems and Control · Cross-listed from cs.LG
Distributionally Robust and Safe Imitation Learning
Ahmed Aboudonia and Naira Hovakimyan
Imitation learning (IL) has achieved remarkable success in complex decision-making tasks. However, its performance is highly sensitive to distribution shifts, which can pose significant safety risks. We propose a distributionally robust and safe IL framework that explicitly addresses both policy-induced and uncertainty-induced distribution shifts. Our approach develops a unified framework leveraging Taylor Series Imitation Learning (TaSIL) to mitigate policy-induced shifts and distributionally robust adaptive control to handle uncertainty-induced shifts. This architecture enables the formulation of an IL problem that optimizes performance under distributional uncertainty while systematically accounting for safety constraints. We demonstrate the effectiveness of the proposed approach on an unmanned aerial vehicle (
UAV) case study where the
UAV performs a task in an uncertain environment while avoiding unsafe regions.
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Signal Processing
Parametric Diffraction-Based Object Sensing: Modeling, Estimation, and Fundamental Limits
Jiaqi Xu, Bjorn Ottersten and A. Lee Swindlehurst
This paper proposes a rigorous framework for sensing of environmental objects using diffraction mechanisms prevalent at wireless communication frequencies. Specifically, we develop a physics-consistent parameterized diffraction channel model, derive maximum likelihood (ML) approaches for estimating the blockage shape, range, and source directions of arrival (DoAs), and quantify fundamental performance limits via the Cramér–Rao bound (CRB). In our physics-based modeling, we integrate various approximations for the wave propagation (far-field, paraxial Fresnel, and exact near-field regimes), enabling a wide range of applicability. The underlying model is frequency-agnostic, and we derive Fresnel-number scaling laws that map the diffraction pattern, and hence the estimation problem, across carrier frequency, object size, and range. We quantify the maximum likelihood estimation performance and its relationship to the CRB, and we study the impact of the modeling approximations developed in this work. Numerical results demonstrate that ML
estimators closely approach the CRB at moderate to high signal-to-noise ratio (SNR), and highlight the utility of diffraction-based modeling for high-fidelity blockage characterization.
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Audio and Speech Processing
Improving Text-to-Audio Instruction Following via Fine-Grained Feedback from Audio-Aware Large Language Models
Chun-Yi Kuan, Siwon Kim, Byeonggeun Kim et al. (+7 more)
Recent text-to-audio models generate high-quality audio, but often fail to follow instructions involving multiple sound events and temporal order. This gap arises because existing evaluation and training signals mainly emphasize global similarity or perceptual quality, with limited supervision on instruction-level correctness. We propose an instruction-level framework that uses audio-aware large
language models (ALLMs) as fine-grained judges to verify target event presence and temporal relations in generated audio. After validating ALLM judgments on
benchmarks and through human verification, we use their feedback to construct preference pairs for direct preference optimization. We further introduce S3Bench, a narrative
benchmark for evaluating multi-event temporal instruction following. Experiments show that our method improves event completeness, temporal ordering, and joint instruction-following accuracy across existing
benchmarks and S3Bench, while maintaining audio quality.
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All authors Chun-Yi Kuan, Siwon Kim, Byeonggeun Kim, Suyoun Kim, Bo-Ru Lu, Qingming Tang, Ankur Gandhe, Hung-yi Lee, Chieh-Chi Kao, Chao Wang
Systems and Control
Change-Aware Self-Adaptive AI-Aided Kalman Filters With Neural Change Point Detection
Wenyi Zhang, Xiaoyong Ni, Nir Shlezinger et al. (+1 more)
Reliable state estimation in dynamical systems is often challenged by model mismatches, unknown noise statistics, and temporal variations. While AI-aided Kalman filters such as KalmanNet leverage deep learning to enhance classical estimation, they remain vulnerable to distribution shifts and lack mechanisms for autonomous adaptation. This work introduces Change-Aware Self-Adaptive KalmanNet (CASA-KalmanNet), an online adaptation framework that integrates a dedicated neural module, termed CPDNet, to monitor the interpretable internal features of KalmanNet and provide soft indicators of reliability degradation. These indicators dynamically regulate an online learning process, enabling data-efficient and timely adaptation to both abrupt and gradual changes in the system without requiring additional state labels from the changed regime. Numerical experiments on linear and nonlinear state-space models show that CASA-KalmanNet consistently outperforms existing learning-based filters under model mismatch, while approaching the accuracy of optimal classical methods with full domain knowledge.
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All authors Wenyi Zhang, Xiaoyong Ni, Nir Shlezinger, Zengfu Wang
Signal Processing
Fine-Grained Open-Set Fault Diagnosis via Metric-Guided Time-Frequency Configuration Selection and Class-Specific Autoencoders
Youngjae Jeon and Dongjin Lee
Reliable fault diagnosis of rotating machinery is essential for the safe and stable operation of industrial systems. Although deep learning methods perform well under closed-set conditions, real machinery may encounter previously unseen fault states. Existing open-set fault diagnosis (OSFD) methods remain limited in fine-grained severity diagnosis because they often rely on coarse type levels, heuristically selected Short-Time
Fourier Transform (STFT) settings, and global class boundaries. We propose a fine-grained OSFD method that combines metric-guided data-centric (MGDC) STFT configuration selection with class-specific autoencoder (CSAE)-based anomaly rejection. MGDC screens candidate STFT configurations using the Silhouette score computed from spectrogram representations, identifying promising time-frequency representations before network training. The diagnostic model then uses a bank of CSAEs to learn compact class-specific
manifolds for known degradation states. During inference, reconstruction-error-based class affinity identifies known classes, while a dual-criteria mechanism based on latent dimension-wise boundaries and class-specific reconstruction error rejects unknown samples. Experiments on the Case Western Reserve University (CWRU) and Paderborn University (PU) bearing
datasets show that the proposed method achieves H-scores of 0.9924 and 0.9509 for fine-grained fault severity diagnosis. MGDC also identifies the best-performing configuration found by exhaustive search while evaluating only 9 of 38 candidates on CWRU and 2 of 39 candidates on PU, reducing the selection cost by factors of 5.69 and 29.87, respectively. These results indicate that the proposed method supports accurate open-set severity diagnosis with substantially lower configuration-selection cost.
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