Audio and Speech Processing
BabAR: from phoneme recognition to developmental measures of young children's speech production
Marvin Lavechin, Elika Bergelson and Roger Levy
Studying early
speech development at scale requires automatic tools, yet automatic phoneme recognition, especially for young children, remains largely unsolved. Building on decades of data collection, we curate TinyVox, a corpus of more than half a million phonetically transcribed child vocalizations in English, French, Portuguese, German, and Spanish. We use TinyVox to train BabAR, a cross-linguistic phoneme recognition system for child
speech. We find that pretraining the system on
multilingual child-centered daylong recordings substantially outperforms alternatives, and that providing 20 seconds of surrounding audio context during fine-tuning further improves performance. Error analyses show that substitutions predominantly fall within the same broad phonetic categories, suggesting suitability for coarse-grained developmental analyses. We validate BabAR by showing that its automatic measures of
speech maturity align with developmental estimates from the literature.
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Image and Video Processing
Limited-Angle CT Reconstruction Using Multi-Volume Latent Consistency Model
Hinako Isogai, Naruki Murahashi, Mitsuhiro Nakamura et al. (+1 more)
Limited-angle computed
tomography (LACT) reconstruction is an inverse problem with severe ill-posedness arising from missing projection angles, and it is difficult to restore high-precision images without sufficient prior knowledge. In recent years, machine learning methods represented by
diffusion models have demonstrated high image generation capabilities. However, accurate restoration of three-dimensional structures of organs and vessels and preservation of contrast remain challenges, and the impact of differences in diverse clinical imaging conditions such as field of view (FOV) and projection angle range on reconstruction accuracy has not been sufficiently investigated. In this study, we propose a multi-volume latent
diffusion model that uses three-dimensional latent representations obtained from multiple effective fields of view as guidance for LACT reconstruction in clinical practical problems. The proposed method achieves fast and stable inference by introducing consistency models into latent space, and enables high-precision preservation of organ boundary information and internal structures under different FOV conditions through a Multi-volume encoder that acquires latent variables from different scales of the global region and central region. The evaluation experiments demonstrated that the proposed method achieved high-precision synthetic CT image generation compared to existing methods. Under the limited-angle condition of 60 degrees, MAE of 10.12 HU and SSIM of 0.9677 were achieved, and under the extreme limited-angle condition of 30 degrees, MAE of 16.69 HU and SSIM of 0.9393 were achieved. Furthermore, stable reconstruction performance was demonstrated even for unknown projection angle conditions not included during training, confirming the applicability to diverse imaging conditions in clinical practice.
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All authors Hinako Isogai, Naruki Murahashi, Mitsuhiro Nakamura, Megumi Nakao
Systems and Control
Uncertainty and Autarky: Cooperative Game Theory for Stable Local Energy Market Partitioning
Saurabh Vaishampayan and Maryam Kamgarpour
Local energy
markets empower prosumers in distribution grids to form coalitions for collective self-consumption. An open question is to analyze the scale and composition of local energy
market coalitions formed by strategic prosumers in distribution grids. This analysis must account for grid constraints, stochasticity of load and generation, as well as the interaction between possibly multiple local energy
markets in the distribution grid. In this work, we present a cooperative game theoretic framework to study distribution grid partitioning into local energy
markets under uncertain prosumption, grid constraints, and coalitional externalities. We formulate the optimal stable partitioning problem to balance the interests of the grid operator with that of strategic prosumers. Under deterministic load and generation, we show that the largest
market coalition is the optimal stable partition. Under high levels of grid congestion, we show that individual self-consumption corresponds to the optimal stable partition. For the general case of
stochastic prosumption and moderate grid congestion levels, we provide an
algorithm to evaluate the optimal stable partition. We validate our
algorithm and theory using numerical experiments on
benchmark and real world distribution grids. Our results help in understanding the impact of prosumption uncertainty and grid constraints on coalition formation.
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Image and Video Processing · Cross-listed from cs.CV
Generic Camera Calibration using Blurry Images
Zezhun Shi
Camera calibration is the foundation of 3D
vision. Generic camera calibration can yield more accurate results than parametric cam era calibration. However, calibrating a generic camera model using printed calibration boards requires far more images than parametric calibration, making motion blur practically unavoidable for individual users. As a f irst attempt to address this problem, we draw on
geometric constraints and a local parametric illumination model to simultaneously estimate feature locations and spatially varying point spread functions, while re solving the translational ambiguity that need not be considered in con ventional image deblurring tasks. Experimental results validate the effectiveness of our approach.
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Image and Video Processing · Cross-listed from cs.CV
The Impact of Preprocessing Methods on Racial Encoding and Model Robustness in CXR Diagnosis
Dishantkumar Sutariya and Eike Petersen
Deep learning models can identify racial identity with high accuracy from chest X-ray (CXR) recordings. Thus, there is widespread concern about the potential for racial shortcut learning, where a model inadvertently learns to systematically bias its diagnostic predictions as a function of racial identity. Such racial biases threaten healthcare equity and model reliability, as models may systematically misdiagnose certain demographic groups. Since racial shortcuts are diffuse - non-localized and distributed throughout the whole CXR recording - image preprocessing methods may influence racial shortcut learning, yet the potential of such methods for reducing biases remains underexplored. Here, we investigate the effects of image preprocessing methods including lung masking, lung cropping, and Contrast Limited Adaptive Histogram Equalization (CLAHE). These approaches aim to suppress spurious cues encoding racial information while preserving diagnostic accuracy. Our experiments reveal that simple bounding box-based lung cropping can be an effective strategy for reducing racial shortcut learning while maintaining diagnostic model performance, bypassing frequently postulated
fairness-accuracy trade-offs.
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Signal Processing
Revitalizing AR Process Simulation of Non-Gaussian Radar Clutter via Series-Based Analytic Continuation
Xingxing Liao and Junhao Xie
Due to the conceptual simplicity, the linear filtering framework, notably the autoregressive (AR) process, has a long history in simulating clutter sequences with specified probability density functions (PDFs) and autocorrelation functions (ACFs). However, linear filtering inevitably distorts the input distribution, which may lead to inaccurate PDF reproduction or restrict applicability to very simple ACFs. To address these challenges, this study proposes a series-based analytic continuation strategy that revitalizes AR process clutter simulation by accurately precomputing the input pre-distortion required to compensate for AR filtering. First, the moments and cumulants of the AR input are derived based on the input-output relationship of the AR process, facilitating the moment and cumulant expansions of the Laplace transform (LT) and the logarithmic LT around zero, respectively. Second, both series expansions are analytically continued via the Padé approximation (PA) to recover the LT over the full complex plane. Notably, the PA-based continuation of the moment expansion, a conventional choice, can be highly inaccurate when the LT exhibits strong oscillations. By contrast, given the logarithmic LT generally has a simpler structure, the continuation of the cumulant expansion provides a more stable and accurate alternative. Third, the LT recovered from the cumulant expansion facilitates fast simulation of the AR input non-Gaussian white sequence via a random variable transformation method, thereby enabling an efficient AR process. Finally, simulations demonstrate that the proposed strategy enables accurate and fast simulation of non-Gaussian correlated clutter sequences.
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Image and Video Processing
Anti-Aliasing Snapshot HDR Imaging Using Non-Regular Sensing
Teresa Stürzenhofäcker, Moritz Klimm, Jürgen Seiler et al. (+1 more)
Snapshot HDR imaging is essential to capture the full dynamic range of a scene in a single exposure, making it essential for
video and dynamic environments where motion prevents the use of multi-exposure techniques or complex hardware set-ups. This work presents a snapshot HDR imaging sensor that is based on spatially varying apertures, implemented by combining two differently sized prototype pixels. The different light integration areas physically extend the dynamic range towards the lower end, compared to a standard high resolution sensor. A non-regular pixel arrangement is suggested, to mitigate aliasing and overcome a loss in spatial resolution that is associated with increased light integration area of the larger prototype pixel. Subsequent reconstruction in the
Fourier domain, where natural images can be sparsely represented allows to recover the image with high detail. The image acquisition approach with the proposed non-regular HDR sensor is simulated and analysed with special emphasis on the spatial resolution. The results suggest the snapshot HDR sensor layout to be an effective way to acquire images with high dynamic range and free from aliasing artefacts.
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All authors Teresa Stürzenhofäcker, Moritz Klimm, Jürgen Seiler, André Kaup
Audio and Speech Processing
PolyBench: A Benchmark for Compositional Reasoning in Polyphonic Audio
Yuanjian Chen, Yang Xiao, Han Yin et al. (+3 more)
Large Audio
Language Models (LALMs) are increasingly capable of
reasoning over audio, yet existing
benchmarks offer limited coverage of
reasoning in polyphonic audio, where multiple sound events co-occur and induce compositional structure. To address this gap, we introduce PolyBench, a
benchmark designed to evaluate compositional
reasoning in polyphonic audio, comprising five evaluation subsets that cover counting, classification, detection, concurrency, and duration estimation, all of which require
reasoning over multiple concurrent events and their relations. Our evaluation of state-of-the-art LALMs reveals consistent performance degradation in polyphonic settings, indicating a fundamental bottleneck in current LALMs.
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All authors Yuanjian Chen, Yang Xiao, Han Yin, Xubo Liu, Jinjie Huang, Ting Dang
Signal Processing
A Fully Open-source Implementation of an Analog 8-PAM Demapper for High-speed Communications
Mohamed Aiham Hemza, Alex Alvarado, Krzysztof Herman et al. (+1 more)
Spectrally-efficient communication systems rely on the use of multi-level modulation formats. At the receiver side, a demodulator is often used to extract soft information about the transmitted bits. Such a demodulator is typically implemented in the digital domain. However, analog implementations of such demodulators are also possible. In this paper, we design and simulate an analog 8-ary pulse-amplitude modulation (8-PAM) demapper in IHP SG13G2 SiGe BiCMOS technology. We generalize and improve a design available in the literature for 4-PAM. A fully MOSFET-based 8-PAM design is proposed. Our simulations and design are completely based on open-source IC design tools. Our results show an energy efficiency of 0.33 pJ/bit for a data rate of 1Gbit/s.
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All authors Mohamed Aiham Hemza, Alex Alvarado, Krzysztof Herman, Piyush Kaul
Systems and Control
Trajectory Tracking for Uncrewed Surface Vessels with Input Saturation and Dynamic Motion Constraints
Ram Milan Kumar Verma, Shashi Ranjan Kumar and Hemendra Arya
This work addresses the problem of constrained motion control of the uncrewed surface vessels. The constraints are imposed on states/inputs of the vehicles due to the physical limitations, mission requirements, and safety considerations. We develop a nonlinear feedback controller utilizing log-type Barrier Lyapunov Functions to enforce static and dynamic motion constraints. The proposed scheme uniquely addresses asymmetric constraints on position and heading alongside symmetric constraints on surge, sway, and yaw rates. Additionally, a smooth input saturation model is incorporated in the design to guarantee stability even under actuator bounds, which, if unaccounted for, can lead to severe performance degradation and poor tracking. Rigorous Lyapunov stability analysis shows that the closed-loop system remains stable and that all state variables remain within their prescribed bounds at all times, provided the initial conditions also lie within those bounds. Numerical simulations demonstrate the effectiveness of the proposed strategies for surface vessels without violating the motion and actuator constraints.
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Audio and Speech Processing
Voice Timbre Attribute Detection with Compact and Interpretable Training-Free Acoustic Parameters
Aemon Yat Fei Chiu, Yujia Xiao, Qiuqiang Kong et al. (+1 more)
Voice timbre attribute detection (vTAD) is the task of determining the relative intensity of timbre attributes between
speech utterances. Voice timbre is a crucial yet inherently complex component of
speech perception. While deep neural network (DNN)
embeddings perform well in speaker modelling, they often act as black-box representations with limited physical interpretability and high computational cost. In this work, a compact acoustic parameter set is investigated for vTAD. The set captures important acoustic measures and their temporal dynamics which are found to be crucial in the task. Despite its simplicity, the acoustic parameter set is competitive, outperforming conventional cepstral features and supervised DNN
embeddings, and approaching state-of-the-art self-supervised models. Importantly, the studied set require no trainable parameters, incur negligible computation, and offer explicit interpretability for analysing physical traits behind human timbre perception.
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All authors Aemon Yat Fei Chiu, Yujia Xiao, Qiuqiang Kong, Tan Lee
Image and Video Processing · Cross-listed from cs.CV
A 360-degree Multi-camera System for Blue Emergency Light Detection Using Color Attention RT-DETR and the ABLDataset
Francisco Vacalebri-Lloret, Lucas Banchero, Jose J. Lopez et al. (+1 more)
This study presents an advanced system for detecting blue lights on emergency vehicles, developed using ABLDataset, a curated
dataset that includes images of European emergency vehicles under various climatic and geographic conditions. The system employs a configuration of four fisheye cameras, each with a 180-degree horizontal field of view, mounted on the sides of the vehicle. A calibration process enables the azimuthal localization of the detections. Additionally, a comparative analysis of major deep neural network
algorithms was conducted, including YOLO (v5, v8, and v10), RetinaNet, Faster R-CNN, and RT-DETR. RT-DETR was selected as the base model and enhanced through the incorporation of a color
attention block, achieving an accuracy of 94.7 percent and a recall of 94.1 percent on the test set, with field test detections reaching up to 70 meters. Furthermore, the system estimates the approach angle of the emergency vehicle relative to the center of the car using
geometric transformations. Designed for integration into a
multimodal system that combines visual and acoustic data, this system has demonstrated high efficiency, offering a promising approach to enhancing Advanced Driver Assistance Systems (ADAS) and road safety.
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All authors Francisco Vacalebri-Lloret, Lucas Banchero, Jose J. Lopez, Jose M. Mossi
Signal Processing
Label Hijacking in Track Consensus-Based Distributed Multi-Target Tracking
Helena Calatrava, Shuo Tang and Pau Closas
Distributed multi-target tracking (DMTT) in limited field-of-view (FoV) sensor networks commonly suffers from label inconsistency, whereby different nodes disagree on the identity of the same target. Recent track-consensus DMTT (TC-DMTT) strategies mitigate this issue by enforcing kinematic and label agreement through metric-based track matching. Nevertheless, their behavior under
adversarial conditions remains largely unexplored. In this paper, we reveal identity-level vulnerabilities in TC-DMTT and introduce the concept of label hijacking: an attack in which an adversary injects spoofed tracks to corrupt target identities across the network. Drawing on an analogy to classical pull-off deception in radar, we formalize a notion of attack stealthiness and derive an optimization-based strategy for crafting such attacks. A three-sensor network case study demonstrates the impact of the proposed attack on label consistency and tracking accuracy, showing successful target impersonation. Overall, this work highlights the need to rethink robustness at the consensus layer in DMTT frameworks.
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Systems and Control
Formal Entropy-Regularized Control of Stochastic Systems
Menno van Zutphen, Giannis Delimpaltadakis and Duarte J. Antunes
Analyzing and controlling system
entropy is a powerful tool for regulating predictability of control systems. Applications benefiting from such approaches range from reinforcement learning and data security to human-
robot collaboration. In continuous-state
stochastic systems, accurate
entropy analysis and control remains a challenge. In recent years, finite-state abstractions of continuous systems have enabled control synthesis with formal performance guarantees on objectives such as stage costs. However, these results do not extend to
entropy-based performance measures. We solve this problem by first obtaining bounds on the
entropy of system discretizations using traditional formal-abstractions results, and then obtaining an additional bound on the difference between the
entropy of a continuous distribution and that of its discretization. The resulting theory enables formal
entropy-aware controller synthesis that trades predictability against control performance while preserving formal guarantees for the original continuous system. More specifically, we focus on minimizing the linear combination of the KL divergence of the system trajectory distribution to uniform – our system
entropy metric – and a generic cumulative cost. We note that the bound we derive on the difference between the KL divergence to uniform of a given continuous distribution and its discretization can also be relevant in more general information-theoretic contexts. A set of case studies illustrates the effectiveness of the method.
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Systems and Control
Receding-Horizon Maximum-Likelihood Estimation of Neural-ODE Dynamics and Thresholds from Event Cameras
Kazumune Hashimoto, Kazunobu Serizawa and Masako Kishida
Event cameras emit asynchronous brightness-change events where each pixel triggers an event when the last event exceeds a threshold, yielding a history-dependent measurement model. We address online maximum-likelihood identification of continuous-time dynamics from such streams. The latent state follows a Neural ODE and is mapped to predicted log-intensity through a differentiable state-to-image model. We model events with a history-dependent marked point process whose conditional intensity is a smooth surrogate of contrast-threshold triggering, treating the contrast threshold as an unknown parameter. The resulting log-likelihood consists of an event term and a compensator integral. We propose a receding-horizon
estimator that performs a few gradient steps per update on a receding horizon window. For streaming evaluation, we store two scalars per pixel (last-event time and estimated log-intensity at that time) and approximate the compensator via Monte Carlo pixel subsampling. Synthetic experiments demonstrate joint recovery of dynamics parameters and the contrast threshold, and characterize accuracy–latency trade-offs with respect to the window length.
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Systems and Control
A Unified Hybrid Control Architecture for Multi-DOF Robotic Manipulators
Xinyu Qiao, Yongyang Xiong, Yu Han et al. (+1 more)
Multi-degree-of-freedom (DOF) robotic manipulators exhibit strongly nonlinear, high-dimensional, and coupled dynamics, posing significant challenges for controller design. To address these issues, this work proposes a unified hybrid control architecture that integrates model predictive control (MPC) with feedback regulation, together with a stability analysis of the proposed scheme. The proposed approach mitigates the optimization difficulty associated with high-dimensional nonlinear systems and enhances overall control performance. Furthermore, a hardware implementation scheme based on machine learning (ML) is proposed to achieve high computational efficiency while maintaining control accuracy. Finally, simulation and hardware experiments under external disturbances validate the proposed architecture, demonstrating its superior performance, hardware feasibility, and generalization capability for multi-DOF manipulation tasks.
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All authors Xinyu Qiao, Yongyang Xiong, Yu Han, Keyou You
Systems and Control
Design of Grid Forming Multi Timescale Coordinated Control Strategies for Dynamic Virtual Power Plants
Yan Tong, Qin Wang, Sihao Chen et al. (+2 more)
As the penetration level of distributed energy resources (DERs) continues to rise, traditional frequency and voltage support from synchronous machines declines. This weakens grid stability and increases the need for fast and adaptive control in a dynamic manner, especially in weak grids. However, most virtual power plants (VPPs) rely on static aggregation and plan based resource allocation strategies. These methods overlook differences in device response times and limit flexibility for ancillary services. To address this issue, we propose a dynamic virtual power plant (DVPP) that coordinates heterogeneous resources across multiple time scales using grid forming control. We first contrast grid following and grid forming converters: grid following designs rely on a phase locked loop which can undermine stability in weak grids, whereas our DVPP applies virtual synchronous generator control at the aggregate level to provide effective inertia and damping. Then, we introduce a dynamic participation factor framework that measures each device s contribution through the frequency active power and voltage reactive power loops. Exploiting device heterogeneity, we adopt a banded allocation strategy: slow resources manage steady state and low frequency regulation; intermediate resources smooth transitions; and fast resources deliver rapid response and high frequency damping. Comparative simulations demonstrate that this coordinated, timescale aware approach enhances stability and ancillary service performance compared to conventional VPPs.
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All authors Yan Tong, Qin Wang, Sihao Chen, Xue Hu, Zhaoyuan Wu
Image and Video Processing
HoloPASWIN: Robust Inline Holographic Reconstruction via Physics-Aware Swin Transformers
Gökhan Koçmarl{\i} and G. Bora Esmer
In-line digital holography (DIH) is a widely used lensless imaging technique, valued for its simplicity and capability to image samples at high throughput. However, capturing only intensity of the interference pattern during the recording process gives rise to some unwanted terms such as cross-term and twin-image. The cross-term can be suppressed by adjusting the intensity of reference wave, but the twin-image problem remains. The twin-image is a spectral artifact that superimposes a defocused conjugate wave onto the reconstructed object, severely degrading image quality. While deep learning has recently emerged as a powerful tool for phase
retrieval, traditional Convolutional Neural Networks (CNNs) are limited by their local receptive fields, making them less effective at capturing the global diffraction patterns inherent in holography. In this study, we introduce HoloPASWIN, a physics-aware deep learning framework based on the Swin
Transformer architecture. By leveraging hierarchical shifted-window
attention, our model efficiently captures both local details and long-range dependencies essential for accurate
holographic reconstruction. We propose a comprehensive loss function that integrates frequency-domain constraints with physical consistency via a differentiable angular spectrum propagator, ensuring high spectral fidelity. Validated on a large-scale synthetic
dataset of 25,000 samples with diverse noise configurations (speckle, shot, read, and dark noise), HoloPASWIN demonstrates effective twin-image suppression and robust reconstruction quality.
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Systems and Control · Cross-listed from cs.RO
U-OBCA: Uncertainty-Aware Optimization-Based Collision Avoidance via Wasserstein Distributionally Robust Chance Constraints
Zehao Wang, Yuxuan Tang, Han Zhang et al. (+2 more)
Uncertainties arising from localization error, trajectory prediction errors of the moving obstacles and environmental disturbances pose significant challenges to
robot's safe
navigation. Existing uncertainty-aware planners often approximate polygon-shaped
robots and obstacles using simple
geometric primitives such as circles or ellipses. Though computationally convenient, these approximations substantially shrink the feasible space, leading to overly conservative trajectories and even planning failure in narrow environments. In addition, many such methods rely on specific assumptions about noise distributions, which may not hold in practice and thus limit their performance guarantees. To address these limitations, we extend the Optimization-Based Collision Avoidance (OBCA) framework to an uncertainty-aware formulation, termed U-OBCA. The proposed method explicitly accounts for the collision risk between polygon-shaped
robots and obstacles by formulating OBCA-based chance constraints, and hence avoiding
geometric simplifications and reducing unnecessary conservatism. These probabilistic constraints are further tightened into deterministic nonlinear constraints under mild distributional assumptions, which can be solved efficiently by standard numerical optimization solvers. The proposed approach is validated through theoretical analysis, numerical simulations and real-world experiments. The results demonstrate that U-OBCA significantly mitigates the conservatism in trajectory planning and achieves higher
navigation efficiency compared to existing baseline methods, particularly in narrow and cluttered environments.
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All authors Zehao Wang, Yuxuan Tang, Han Zhang, Jingchuan Wang, Weidong Chen
Signal Processing
A Method to Derate the Rate-Dependency in the Pass-Band Droop of Comb Decimators
Ealwan Lee
This paper presents a method to derate the dependency on the decimation factor, $M$, of the pass-band droop inherent to $N$-th ordered comb decimators. It is achieved by cascading a symmetric 3-tap FIR filter in the integral stage of the corresponding comb decimator and choosing the coefficients only as a function of order $N$. The proposed derating method derived from the conventional comb decimator can be readily applied to any recently developed comb decimator and droop-compensation filter design method.
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Systems and Control
The Vertical Challenge of Low-Altitude Economy: Why We Need a Unified Height System?
Shuaichen Yan, Xiao Hu, Jiayang Sun et al. (+5 more)
The explosive growth of the low-altitude economy, driven by eVTOLs and
UAVs, demands a unified digital infrastructure to ensure safety and scalability. However, the current aviation vertical references are dangerously fragmented: manned aviation relies on barometric pressure, cartography uses Mean Sea Level (MSL), and obstacle avoidance depends on Above Ground Level (AGL). This fragmentation creates significant ambiguity for autonomous systems and hinders cross-stakeholder interoperability. In this article, we propose Height Above Ellipsoid (HAE) as the standardized vertical reference for lower airspace. Unlike legacy systems prone to environmental drift and inconsistent datums, HAE provides a globally consistent, GNSS-native, and mathematically stable reference. We present a pragmatic bidirectional transformation framework to bridge HAE with legacy systems and demonstrate its efficacy through (1) real-world implementation in Shenzhen's partitioned airspace management, and (2) a probabilistic risk assessment driven by empirical flight logs from the PX4 ecosystem. Results show that transitioning to HAE reduces the required vertical separation minimum, effectively increasing dynamic airspace capacity while maintaining a target safety level. This work offers a roadmap for transitioning from analog height keeping to a digital-native vertical standard.
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All authors Shuaichen Yan, Xiao Hu, Jiayang Sun, Zeyuan Yang, Shipeng Li, Heung-Yeung Shum, Shijun Yin, Yuqing Tang
Systems and Control · Cross-listed from math.OC
Policy Optimization of Mixed H2/H-infinity Control: Benign Nonconvexity and Global Optimality
Chih-Fan Pai, Yuto Watanabe, Yujie Tang et al. (+1 more)
Mixed H2/H-infinity control balances performance and robustness by minimizing an H2 cost bound subject to an H-infinity constraint. However, classical Riccati/LMI solutions offer limited insight into the nonconvex optimization landscape and do not readily scale to large-scale or data-driven settings. In this paper, we revisit mixed H2/H-infinity control from a modern policy optimization viewpoint, including the general two-channel and single-channel cases. One central result is that both cases enjoy a benign nonconvex structure: every stationary point is globally optimal. We characterize the H-infinity-constrained feasible set, which is open, path-connected, with boundary given exactly by policies saturating the H-infinity constraint. We also show that the mixed objective is real analytic in the interior with explicit gradient formulas. Our key analysis builds on an Extended Convex Lifting (ECL) framework that bridges nonconvex policy optimization and convex reformulations. The ECL constructions rely on non-strict Riccati inequalities that allow us to characterize global optimality. These insights reveal hidden convexity in mixed H2/H-infinity control and facilitate the design of scalable policy iteration methods in large-scale settings.
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All authors Chih-Fan Pai, Yuto Watanabe, Yujie Tang, Yang Zheng
Audio and Speech Processing
An Approach to Simultaneous Acquisition of Real-Time MRI Video, EEG, and Surface EMG for Articulatory, Brain, and Muscle Activity During Speech Production
Jihwan Lee, Parsa Razmara, Kevin Huang et al. (+16 more)
Speech production is a complex process spanning neural planning, motor control, muscle activation, and articulatory kinematics. While the acoustic
speech signal is the most accessible product of the
speech production act, it does not directly reveal its causal neurophysiological substrates. We present the first simultaneous acquisition of real-time (dynamic) MRI,
EEG, and surface EMG, capturing several key aspects of the
speech production chain:
brain signals, muscle activations, and articulatory movements. This
multimodal acquisition paradigm presents substantial technical challenges, including MRI-induced electromagnetic interference and myogenic artifacts. To mitigate these, we introduce an artifact suppression pipeline tailored to this tri-modal setting. Once fully developed, this framework is poised to offer an unprecedented window into
speech neuroscience and insights leading to
brain-computer interface advances. The source code and data are available.
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All authors Jihwan Lee, Parsa Razmara, Kevin Huang, Sean Foley, Aditya Kommineni, Haley Hsu, Woojae Jeong, Prakash Kumar, Xuan Shi, Yoonjeong Lee, Tiantian Feng, Takfarinas Medani, Ye Tian, Sudarsana Reddy Kadiri, Krishna S. Nayak, Dani Byrd, Louis Goldstein, Richard M. Leahy, Shrikanth Narayanan
Signal Processing
Wide-Area GNSS Interference Monitoring with CYGNSS GNSS-R Delay-Doppler Noise Floor Observations
Ji-Hyeon Shin and Pyo-Woong Son
Global
Navigation Satellite System (GNSS) interference increasingly threatens positioning,
navigation, and timing services and requires monitoring over areas beyond dense ground networks. Low Earth orbit satellites provide complementary regional coverage, and previous studies have shown that terrestrial
radio-frequency interference (RFI) produces measurable anomalies in spaceborne GNSS and GNSS-reflectometry observations. The Cyclone Global
Navigation Satellite System (CYGNSS) has been used to map and characterize interference, but existing approaches generally depend on long-term data accumulation, full Delay-Doppler Map (DDM) processing, or special raw intermediate-frequency acquisitions and lack epoch-level validation against independent data. This paper presents a lightweight detector using four channel-wise DDM noise-floor values routinely distributed in CYGNSS Level-1 products. Because the channels observe different reflected signals through two nadir
antennas, interference-related elevations may be strongly asymmetric. The detector uses the channel maximum to preserve these responses and applies temporal-persistence or multi-satellite-concurrence screening to reject isolated anomalies. Evaluation at the White Sands Missile Range used an independent reference formed from Federal Aviation Administration Notices to Air Missions and concurrent Automatic Dependent Surveillance-Broadcast
navigation-integrity degradation. Relative to the single-epoch mean baseline, the proposed detector increased the probability of detection by 0.063 at the same observed false-alarm rate, with a 95% confidence interval of [0.034, 0.094]. In the Middle East, it also detected both vertical-stripe and atypical elevated-background DDM structures. These results demonstrate lightweight epoch-level monitoring of wide-area or temporally sustained GNSS interference using routine Level-1 products.
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Systems and Control · Cross-listed from cs.RO
Data-Driven Control of a Magnetically Actuated Fish-Like Robot
Akiyuki Koyama and Hiroaki Kawashima
Magnetically actuated fish-like
robots offer promising solutions for
underwater exploration due to their miniaturization and agility; however, precise control remains a significant challenge because of nonlinear fluid dynamics, flexible fin hysteresis, and the variable-duration control steps inherent to the actuation mechanism. This paper proposes a comprehensive data-driven control framework to address these complexities without relying on analytical modeling. Our methodology comprises three core components: 1) developing a forward dynamics model (FDM) using a neural network trained on real-world experimental data to capture state transitions under varying time steps; 2) integrating this FDM into a gradient-based model predictive control (G-MPC) architecture to optimize control inputs for path following; and 3) applying imitation learning to approximate the G-MPC policy, thereby reducing the computational cost for real-time implementation. We validate the approach through simulations utilizing the identified dynamics model. The results demonstrate that the G-MPC framework achieves accurate path convergence with minimal root mean square error (RMSE), and the imitation learning controller (ILC) effectively replicates this performance. This study highlights the potential of data-driven control strategies for the precise
navigation of miniature, fish-like soft
robots.
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Signal Processing
MIMO Channel Prediction via Deep Learning-based Conformal Bayes Filter
Dongwon Kim, Jinu Gong and Joonhyuk Kang
Channel prediction has emerged as an effective solution for acquiring accurate channel state information (CSI) in the presense of channel aging. Existing methods have inherent limitations, with conventional Kalman filter (KF)-based approach being vulnerable to model mismatch and deep learning (DL)-based approaches producing overconfident predictions. To address these issues, we propose a DL-based conformal Bayes filter (DCBF) that integrates DL-based prediction, conformal
quantile regression (CQR), and
Bayesian filtering. The proposed framework enables principled fusion of calibrated priors and observations, yielding reliable channel predictions with the calibrated uncertainty. Simulation results demonstrate that DCBF significantly improves DL-based prediction and outperforms the KF-based method.
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Systems and Control · Cross-listed from cs.RO
Adaptive Policy Switching of Two-Wheeled Differential Robots for Traversing over Diverse Terrains
Haruki Izawa, Takeshi Takai, Shingo Kitano et al. (+2 more)
Exploring lunar lava tubes requires
robots to traverse without human intervention. Because pre-trained policies cannot fully cover all possible terrain conditions, our goal is to enable adaptive policy switching, where the
robot selects an appropriate terrain-specialized model based on its current terrain features. This study investigates whether terrain types can be estimated effectively using posture-related observations collected during
navigation. We fine-tuned a pre-trained policy using Proximal Policy Optimization (PPO), and then collected the
robot's 3D orientation data as it moved across flat and rough terrain in a simulated lava-tube environment. Our analysis revealed that the standard deviation of the
robot's pitch data shows a clear difference between these two terrain types. Using Gaussian mixture models (GMM), we evaluated terrain classification across various window sizes. An accuracy of more than 98% was achieved when using a 70-step window. The result suggests that short-term orientation data are sufficient for reliable terrain estimation, providing a foundation for adaptive policy switching.
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All authors Haruki Izawa, Takeshi Takai, Shingo Kitano, Mikita Miyaguchi, Hiroaki Kawashima
Systems and Control · Cross-listed from math.OC
Multistage Stochastic Programming for Rare Event Risk Mitigation in Power Systems Management
Daniel Mastropietro and Vyacheslav Kungurtsev
High intermittent renewable penetration in the energy mix presents challenges in robustness for the management of power systems' operation. If a tail realization of the distribution of weather yields a prolonged period of time during which
solar irradiation and wind speed are insufficient for satisfying energy demand, then it becomes critical to ramp up the generation of conventional power plants with adequate foresight. This event trigger is costly, and inaccurate
forecasting can either be wasteful or yield catastrophic undersupply. This encourages particular
attention to accurate modeling of the noise and the resulting dynamics within the aforementioned scenario. In this work we present a method for rare event-aware control of power systems using multi-stage scenario-based
stochastic programming. A Fleming-Viot particle approach is used to bias the scenario generation towards rare realizations of very low wind power, in order to obtain a cost-effective control of conventional power plants that is robust under prolonged renewable energy shortfalls.
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Signal Processing
Intensity Fluctuation Spectra as a Design Guide for Nonlinear-Tolerant Constellation Shaping
Ravneel Prasad and Emanuele Viterbo
Nonlinearity in coherent fiber links is fundamentally driven by the temporal statistics and spectral structure of signal intensity. This paper develops a unified framework that links block-level energy statistics of shaped constellations to the low-frequency features of the intensity-fluctuation power spectral density (PSD), thereby enabling spectral-temporal co-design for nonlinear mitigation. A semi-analytical PSD model is derived for finitely block-shaped symbols (including Constant Composition Distribution Matching (CCDM) and Enumerative Sphere Shaping (ESS)), explicitly exposing contributions from self-beating dependent on symbol energy variance, inter-symbol beating dependent on mean symbol energy, and block-induced energy variance terms. A compact expression for the spectral-dip width is obtained that captures the block length, symbol rate, pulse roll-off, and chromatic dispersion. This yields design rules for lowering the low-frequency content. The low-frequency content most strongly drives the induced XPM. Resulting optimal symbol-rate laws are provided for shaped and unshaped systems, and are validated by Monte-Carlo simulations, which also confirm the distinct low-frequency behaviour of CCDM (suppressed DC) versus ESS (finite DC pedestal at moderate block lengths). The framework consolidates prior time- and frequency-domain views and supplies actionable guidance for choosing block length, symbol rate, and shaping method to reduce nonlinear interference in high-capacity WDM systems.
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Image and Video Processing · Cross-listed from cs.CR
When Denoising Becomes Unsigning: Theoretical and Empirical Analysis of Watermark Fragility Under Diffusion-Based Image Editing
Fai Gu, Qiyu Tang, Te Wen et al. (+2 more)
Robust invisible watermarking systems aim to embed imperceptible payloads that remain decodable after common post-processing such as JPEG compression, cropping, and additive noise. In parallel,
diffusion-based image editing has rapidly matured into a default transformation layer for modern content pipelines, enabling instruction-based editing, object insertion and composition, and interactive
geometric manipulation. This paper studies a subtle but increasingly consequential interaction between these trends:
diffusion-based editing procedures may unintentionally compromise, and in extreme cases practically bypass, robust watermarking mechanisms that were explicitly engineered to survive conventional distortions. We develop a unified view of
diffusion editors that (i) inject substantial Gaussian noise in a latent space and (ii) project back to the natural image
manifold via learned denoising dynamics. Under this view, watermark payloads behave as low-energy, high-frequency signals that are systematically attenuated by the forward
diffusion step and then treated as nuisance variation by the reverse generative process. We formalize this degradation using information-theoretic tools, proving that for broad classes of pixel-level watermark encoders/decoders the mutual information between the watermark payload and the edited output decays toward zero as the editing strength increases, yielding decoding error close to random guessing. We complement the theory with a realistic hypothetical experimental protocol and tables spanning representative watermarking methods and representative
diffusion editors. Finally, we discuss ethical implications, responsible disclosure norms, and concrete design guidelines for watermarking schemes that remain meaningful in the era of generative transformations.
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All authors Fai Gu, Qiyu Tang, Te Wen, Emily Davis, Finn Carter