Image and Video Processing
Pretreatment MRI reveals a latent, molecular-subtype-independent structural phenotype that organizes treatment trajectories and recurrence risk
Dattatreya Kantha and Murray H. Loew
Pathologic complete response and tumor shrinkage measure whether breast cancer responds to neoadjuvant therapy, but not whether that response was structurally favorable, persistent, or hidden beneath volume loss. We built an outcome-blind longitudinal DCE-MRI
manifold from I-SPY2 trajectories to test whether pretreatment imaging carries a structural response phenotype missed by conventional descriptors. The dominant axis of response geometry was not recoverable from the full clinical and genomic stack – age, receptor subtype, MammaPrint, PAM50, treatment arm, and tumor burden – but became strongly recoverable once baseline structural
entropy was added. A constrained representation mapping recovered the same axes as unconstrained decomposition, establishing the structure as intrinsic rather than a post-hoc interpretation. The phenotype persisted through therapy, and as treatment proceeded the volumetric signal faded while
entropy stayed separated – a crossover from burden to structural persistence. Among complete responders, structurally disordered tumors could shrink more early yet remain structurally disordered, a volumetric deception invisible to endpoint labels. External analyses in UCSF, I-SPY1, and Duke established recurrence relevance under representation-dependent boundaries, and a representation-family commensurability assessment showed why feature-name matching is insufficient: the same label can fail, transport, or entangle with extraction geometry. Pretreatment MRI therefore exposes a structural response phenotype that endpoint-based
language leaves invisible – including, among complete responders, a pretreatment imaging signal of structurally distinct response states that awaits prospective validation.
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Systems and Control · Cross-listed from math.OC
Online Modeling and Sequential Convex Programming for Lunar Landing Trajectory Optimization
Zhenbo Wang
This paper presents a guidance framework for lunar powered descent and landing that combines sequential convex programming (SCP) with real-time online model identification. A nonconvex energy-optimal landing problem is developed and then reformulated into a sequence of convex second-order cone programs (SOCPs) through a change of variables, successive linearization, and a lossless second-order cone relaxation of the thrust direction constraint. An online identification layer, built from a recursive least squares (RLS) filter with exponential forgetting and an exponential moving average (EMA) smoother, estimates unknown gravitational, thrust-scale, and mass-gauging perturbations from noisy
navigation measurements and injects a corrected bias term into the dynamics constraint of each convex subproblem at every guidance cycle. Building on this architecture and my prior work in this area, a baseline SCP
algorithm and a receding-horizon online SCP
algorithm with model identification are developed. Also, I try to explore some theoretical foundations, establishing the losslessness of the convex relaxation, the mean-square stability and convergence of the identification filters, the guaranteed convergence of the SCP iteration, and explicit convergence radius and convergence rate results. Numerical simulations across four perturbation scenarios of increasing complexity are implemented in MATLAB using YALMIP and the ECOS solver. The results show that the proposed online
algorithm consistently reduces landing position and velocity error and better tracks the true propellant consumption relative to an uncorrected nominal trajectory, while retaining the predictable convergence and real-time computational properties of convex optimization.
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Systems and Control · Cross-listed from math.OC
Optimality-Informed Neural Networks for Lunar Landing Trajectory Optimization
Zhenbo Wang
This paper develops an Optimality-Informed Neural Network (OINN) approach for the energy-optimal, free-final-time powered descent of a lunar lander from any initial position, velocity, and mass within a bounded operating envelope to a fixed landing site with zero terminal velocity. Building on a recent framework that jointly embeds Pontryagin's minimum principle and the Hamilton-Jacobi-Bellman equation for general nonlinear optimal control, the proposed OINN approach specializes that idea to a lunar landing problem with free time of flight and fixed terminal state. Every boundary and transversality condition is hard-encoded into the network architecture by construction, the closed-form Pontryagin-optimal thrust magnitude and direction law is substituted directly rather than learned, and the remaining state, costate, and an auxiliary value-function output are trained against a physics-residual loss formed entirely from the necessary conditions of optimality, with no precomputed optimal trajectories required. A preliminary theoretical analysis is explored, establishing a
stochastic-optimization stationarity guarantee for the offline training procedure, an explicit bound translating the achieved training residual into bounds on touchdown position, touchdown velocity, and flight-time error, and a fixed, input-independent onboard computational and
memory cost suitable for real-time deployment. Numerical simulations evaluate the trained policy, with no retraining, against an independently solved indirect-method boundary-value problem at six representative initial states spanning the operating envelope and against eighty additional Monte Carlo simulation runs, demonstrating close agreement with the indirect-method solution and consistently small dynamics and transversality residuals throughout the envelope.
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Systems and Control
Physics-Informed Dynamic State Estimation for Current Transformers Using Graph Neural Networks
Michael A. Boateng, Gabriel Gauderman and Nathalie Uwamahoro
Current
transformers are fundamental to power system protection and measurement, yet transient core saturation can severely distort the secondary current and degrade measurement accuracy. Existing dynamic state estimation methods rely mainly on numerical discretisation and iterative solvers, but their initialisation is not informed by the physical dependency structure of the estimation problem, which limits robustness under noisy conditions. This paper presents a physics-informed enhancement for current
transformer dynamic state estimation using COMTRADE measurements generated in WinIGS-T. A structured
benchmark of four discretisation schemes and three iterative solvers identifies Gauss-Newton with Quadratic discretisation as the strongest baseline. To address the limitation of conventional cold-start initialisation, a graph neural network is constructed from the Jacobian sparsity pattern to generate physics-informed initial state estimates. The proposed warm-start strategy improves
estimator conditioning and achieves average gains of 25% in initialisation distance and 38% in initial weighted objective value across all tested SNR levels. The results demonstrate that
embedding physical structure into the initialisation stage improves the robustness of CT saturation correction and supports more reliable measurement and protection performance in modern power grids.
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Signal Processing
Metasurface embodied intelligence through electromagnetic world model
Che Liu, Zhenhao Fu, Qian Ma et al. (+4 more)
Mastering invisible electromagnetic (EM) environment and sculpting
radio waves with the dexterity of manipulating light or matter have long been aspirations in physics and information science. While information metasurfaces (IMSs) provide the physical interface to program EM wavefields, their real-world autonomy is fundamentally limited by environmental 'blindness' and the prohibitive overhead of site-specific and trial-and-error retraining. Here we propose metasurface
embodied intelligence through world model (metaEI-WM), a universal and out-of-the-box paradigm that achieves expert-level performance without on-site fine-tuning. In contrast to purely data-driven
agents, metaEI-WM establishes a fundamental understanding of the EM dynamics by integrating fully automated semantic environment modelling with embedded electrodynamic priors. By anticipating future scenarios in silico, it optimizes the IMS coding configurations to dynamically shape EM environments on demand. We show that metaEI-WM successfully enables zero-latency non-line-of-sight signal enhancements, symbiotic communications, and contactless physiological sensing across highly complex and unseen indoor scenarios. To the best of our knowledge, metaEI-WM is the first paradigm to achieve end-to-end automation of complex spatial channel manipulation tasks ab initio, requiring neither human-annotated data nor online training. This framework bridges the gap between digital intelligence and physical-layer wave dynamics, offering a scalable solution for robust and self-managing wireless ecosystems.
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All authors Che Liu, Zhenhao Fu, Qian Ma, Jiajing Wu, Wen Ming Yu, Lianlin Li, Tie Jun Cui
Systems and Control · Cross-listed from cs.SE
Schedulable Job-Level Dependencies for Cause-Effect Chains via Graph Neural Networks
Silviu S. Craciunas, Christian Hakert, Jian-Jia Chen et al. (+2 more)
Modern automotive software architectures comprise large sets of mixed-criticality functions executing on shared multi-core platforms with strict real-time and end-to-end timing requirements. Sensor-to-actuator data propagation in such systems is typically expressed via cause-effect chains with worst-case data-age budgets. Job-level dependencies (JLDs) have been introduced to provide a schedule-agnostic mechanism for bounding the data age independently of the underlying scheduler. The state-of-the-art methods for synthesizing JLDs, however, do not check whether the produced JLDs are enforceable under a concrete scheduling policy or jointly schedulable at the system level. In this paper we propose the first machine-learning-based JLD synthesis method, built around a two-level Graph Neural Network with temperature-controlled sampling that learns the structural patterns connecting cause-effect chain configurations to their JLD solutions. Since learned outputs may not be correct by construction, we embed the GNN in a novel Generate-and-Verify architecture in which a safe DP data-age checker, together with a per-chain EDF feasibility checker and a system-level demand-bound test, accept or reject each candidate. We show that the ML-based generator substantially outperforms the original greedy heuristic while achieving orders-of-magnitude lower synthesis time, demonstrating that learned structural priors can effectively replace exponential propagation-tree enumeration on this class of real-time scheduling problems.
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All authors Silviu S. Craciunas, Christian Hakert, Jian-Jia Chen, Zdeněk Hanzálek, Paul Pop
Systems and Control · Cross-listed from cs.LG
Evaluating Time Series Foundation Models for Electricity Price Forecasting: Contamination Risk, Distributional Shifts, and Covariate Dependence
Zhenghua Pan and Ahmed Aziz Ezzat
Time series foundation models (TSFMs) have shown strong zero-shot
forecasting performance, but their generalization in
covariate-driven, non-stationary settings is underexplored. Electricity price
forecasting (EPF) presents a challenging testbed due to complex temporal dependencies, distributional shifts, and strong reliance on structural and contextual information. We propose a two-
dataset-benchmarking framework for EPF to mitigate contamination risk and enable fair evaluation of TSFMs. We examine key aspects of EPF including point and probabilistic
forecasting performance, tail behavior, price spikes, and comparisons against domain-specific methods. We find that TSFMs are highly competitive and often outperform general-purpose baselines. Yet, their performance depends critically on
covariate support, and they do not consistently surpass domain-specific methods tailored to EPF. Interestingly, simple ensembles of TSFMs and domain-specific methods appear to have significant potential, suggesting that the two approaches capture complementary predictive information.
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Systems and Control
Docking of Autonomous Vehicles with a Stationary Docking Station in 3D Space
Ram Milan Kumar Verma, Shashi Ranjan Kumar and Hemendra Arya
In this letter, we present a strategy for autonomous docking of autonomous vehicles in three-dimensional space. Docking is a safety-critical task and requires expert piloting skills. Vehicles with autonomous docking capabilities are highly desirable in various applications, such as marine vehicle docking, aerial vehicle docking, spacecraft docking, and landing. To dock autonomously with the docking station, the vehicle must align itself to a specific desired orientation relative to the docking station and also reduce speed as it approaches. The vehicle achieves near-zero speed to dock successfully and safely without colliding with the docking station. Inspired by the philosophies from the guidance literature, we present a finite-time sliding mode-based strategy to achieve the same. The range and line-of-sight kinematics relations describing the motion of the vehicle with respect to the stationary docking station are used to steer the vehicle to achieve the desired orientation for docking. This docking strategy is validated in MATLAB\textsuperscript{\textregistered} simulations for various initial locations and orientations of both the vehicle and the docking station.
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Systems and Control · Cross-listed from cs.RO
QuadRocket: An Aerial Robotic Testbed for Adaptive Thrust-Vector Control of Rocket-Like Vehicles
Pedro Santos, Joel Reis, Paulo Oliveira et al. (+1 more)
This paper presents QuadRocket, a quadrotor-based rocket prototype that provides a low-cost, low-risk platform for validating advanced thrust-vector control strategies for launch vehicle-type systems. The prototype consists of a cylindrical main body mounted on top of a quadrotor through a universal joint, forming a flying inverted pendulum with non-negligible inertia. For control design, the coupled system is modeled as a single axisymmetric rigid body actuated by a vectored force applied along its longitudinal axis. A reduced-attitude representation on the two sphere is adopted to explicitly exploit the vehicle's axial
symmetry and to decouple yaw from the thrust-vector direction. On this model, we derive an adaptive backstepping controller that achieves almost global trajectory tracking in the presence of unknown constant disturbances, while a control-point transformation mitigates non minimum-phase behavior. The quadrotor is then treated as a thrust vector actuator, and a dynamic-surface-based attitude controller is designed to track the desired thrust-vector, accounting for actuation dynamics and avoiding explicit differentiation of virtual control signals. The complete architecture is evaluated in simulation and validated experimentally in an indoor motion-capture arena. Results demonstrate accurate trajectory tracking, effective disturbance compensation, and confirm the suitability of the QuadRocket as a versatile testbed for thrust-vector-controlled robotic vehicles.
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All authors Pedro Santos, Joel Reis, Paulo Oliveira, Carlos Silvestre
Audio and Speech Processing · Cross-listed from cs.CL
Audio-Based Understanding of Audiobook Narration Appeal
Shahar Elisha, Mariano Beguerisse-Díaz and Emmanouil Benetos
Narration is central to the audiobook listening experience, shaping how listeners engage with and understand the content. This work explores how narration qualities shape an audiobook's appeal, noting that their effects can vary by genre, title, and audience. We extract vocal and acoustic features (e.g., tone, pace, loudness) from LibriVox using pre-trained audio models and analyse their relationship with consumption data (specifically, view-rate) and their interplay with genre and title. Despite limited consumption data, we find that acoustic information alone has a robust association with appeal, even after accounting for title effects. We further validate these findings using more nuanced proprietary engagement metrics. To our knowledge, this is the first systematic computational study linking narration qualities, genre, title, and audiobook consumption, highlighting the potential of data-driven insights to improve audiobook personalisation and narrator casting.
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Systems and Control
Nonholonomic Source Seeking by Torque Tuning: Local and Semi-Global Feedbacks
Bo Wang
This paper studies source seeking for a torque-controlled nonholonomic vehicle with a laterally displaced scalar sensor. The vehicle has constant forward speed, while its yaw motion is controlled by torque input with unknown inertia and damping. The objective is to steer the vehicle to a source-centered circular motion so that the lateral sensor approaches the unknown source, without using position, heading, source-location, gradient, or source-value information. The proposed torque law combines a fast oscillatory component, which generates averaged steering through symmetric-product approximation, with a slowly tuned bias component, which selects the desired orbit. Two bias-tuning designs are developed. The first is an output-feedback design using only the scalar measurement; it applies a Lie-bracket extremum-seeking update and yields local practical stability. The second is a velocity-assisted design using forward-speed and yaw-rate measurements; it tunes the bias through the yaw-rate tracking error and yields a globally asymptotically stable averaged system, implying semi-global practical stability of the original system. Simulations illustrate the proposed designs.
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Image and Video Processing · Cross-listed from cs.CV
MARVEL: Margin-Aware Robust von Mises-Fischer Expert Learning for Long-Tailed Out-of-Distribution Detection
A.S. Anudeep and Vaanathi Sundaresan
For clinical deployment, it is essential that automated diagnostic systems remain reliable when confronted with previously unseen cases, yet deep models routinely misclassify out-of-distribution (OOD) inputs with high confidence, underscoring the need for more robust OOD detection methods. Although substantial effort has been devoted to improving model robustness, most of the existing literature assumes balanced
datasets, evaluates OOD detection on coarse or non-clinical OOD sources, or lacks comprehensive assessment across diverse OOD scenarios. To address the gaps, we propose a novel methodology trained on diverse and imbalanced medical
datasets and evaluated across a clinically reflective OOD spectrum. Our framework comprises three key components: (1) a Nonlinear von Mises-Fisher (NvMF) classifier capable of learning non-linear decision boundaries, with theoretical proof of its asymptotic connection to cosine classifiers; (2) a multi-expert framework in which margin-aware NvMF classifiers specialise in different regions of label distribution to better handle imbalance; and (3) an outlier expert trained explicitly to distinguish inlier from outlier data, thereby strengthening OOD detection. Evaluation on RFMiD, ISIC2019, and NCTCRC
datasets demonstrates consistent improvements over state-of-the-art methods, achieving mean FPR95 reductions of 8.45%, 13.02%, and 36.90% respectively. These gains are further supported by comprehensive ablations that validated the contributions of each component. This enables reliable identification of unfamiliar cases for deferral to clinicians, supporting safer AI-assisted diagnosis in real-world workflows. Our code is available at https://github.com/redboxup/MARVEL.
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Image and Video Processing
Self-Auditing Residual Drifting for Pathology-Preserving Accelerated Knee MRI
Qing Lyu, Jianxu Wang, Mohammad Kawas et al. (+2 more)
Accelerated
magnetic resonance imaging reduces acquisition time, but reconstruction from undersampled k-space can blur diagnostically relevant structures or introduce failures that are not captured by global image metrics. We propose SA-RDM-DC, a Self-
Auditing Residual generative Drifting Model with Data Consistency for accelerated knee MRI. The method adapts the newly proposed generative drifting paradigm to accelerated MRI by training a physics-conditioned drift field from the zero-filled reconstruction toward the fully sampled residual correction. It predicts image- and missing-k-space residual corrections, enforces data consistency with acquired k-space, uses frequency-aware and residual drifting supervision to recover fine detail, and produces dense error maps and slice-level risk scores in the same inference pass. We evaluate SA-RDM-DC on multi-coil fastMRI knee data at acceleration factors of 4, 8, and 12, with fastMRI+ pathology annotations for region-level and classifier-based task preservation, and on SKM-TEA for zero-shot and fine-tuned protocol-shift evaluation. Compared with zero-filled reconstruction, UNet-image-SENSE, DC-UNet, Score-
Diffusion, ELF-Diff, SENSE-VarNet, and MoDL baselines, SA-RDM-DC achieves the highest SSIM across fastMRI acceleration factors while retaining subsecond per-slice inference and avoiding the long sampling time of iterative
diffusion baselines. In pathology-aware analysis, SA-RDM-DC preserves lesion-region structural fidelity and reduces meniscus prediction instability. Its self-
auditing scores strongly identify high-error reconstructions on fastMRI and partially transfer as a selective-review signal under SKM-TEA protocol shift. These results support reconstruction evaluation that jointly considers image fidelity, pathology preservation, runtime, and case-specific reliability.
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All authors Qing Lyu, Jianxu Wang, Mohammad Kawas, Ge Wang, Christopher T. Whitlow
Signal Processing
Robust Transmission Design for RIS-Assisted RSMA-SWIPT Systems With Movable Antennas Under Hardware Distortions
Muhammad Asif, Asim Ihsan, Irfan Muhammad et al. (+4 more)
This paper investigates a robust transmission design for a multi-user rate-splitting multiple access (RSMA)-based simultaneous wireless information and power transfer (SWIPT) system empowered by movable
antennas (MAs) and a reconfigurable intelligent surface (RIS) under channel state information (CSI) uncertainty and residual hardware impairments (HIs). The effective channels in MAs-enabled systems depend on
antenna positions, causing CSI uncertainty to affect not only active and passive beamforming but also
antenna position optimization. Furthermore, residual HIs distort the effective SINRs, creating additional coupling among beamforming, RIS reflection control, common-rate allocation, power-splitting ratio optimization, and
antenna position optimization. Consequently, the joint impact of CSI uncertainty and HIs leads to a highly coupled and challenging resource allocation problem. To address this challenge, we propose a robust resource allocation framework that jointly optimizes common-rate allocation, transmit beamforming, RIS reflection coefficients, power-splitting ratios, and MAs positions to maximize the achievable sum-rate while satisfying practical system constraints. To obtain an efficient solution, the original problem is decomposed into active beamforming, RIS reflection design, power-splitting ratio optimization, and MAs position optimization subproblems, where tractable convex surrogate functions are constructed to handle the non-convex objective and constraints. Simulation results verify the effectiveness of the proposed framework and demonstrate substantial improvements in achievable sum-rate, robustness against CSI uncertainty and hardware impairments, and convergence performance compared with
benchmark schemes.
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All authors Muhammad Asif, Asim Ihsan, Irfan Muhammad, Mohd Hamza Naim Shaikh, Syed Tariq Shah, Zhu Shoujin, Symeon Chatzinotas
Systems and Control
Generative Autonomous Grid Control: Integrating Decision Transformers with a Two-Stage Safety Stack
Mohamed Shamseldein
The displacement of synchronous generation by inverter-based resources is accelerating power system frequency dynamics beyond the response capability of conventional automatic generation control. This paper presents Autonomous Grid Generation Control with Decision
Transformers, a framework coupling an offline-trained Decision
Transformer with a twostage symbolic safety stack for secondary frequency control. The Decision
Transformer learns a conditional dispatch policy from offline supervisory control and data acquisition records via sequence modeling, eliminating online exploration risks. A Constraint Verification Unit provides sub-ten-millisecond algebraic screening using real-time power transfer distribution factors, while an aggregate digital twin performs swing-equation-based dynamic stability certification. Validated on the Northeast Power Coordinating Council 140-bus system under low-inertia conditions, the proposed controller reduces the area control error integral by over 99% relative to tuned automatic generation control, maintains a 59.4 Hz frequency nadir, and achieves inference latency of approximately 10 ms, well within real-time constraints. Comparative evaluation against a linear quadratic regulator baseline and structural analysis against conservative Q-learning demonstrate the advantages of the sequence-modeling formulation. Small-signal
eigenvalue analysis characterizes the dominant 1.87 Hz electromechanical mode and confirms that the safety stack maintains stable operation across operating points. By falling back to tuned automatic generation control whenever proposals are rejected, the safety stack bounds worst-case performance to industry-standard levels in simulation.
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Systems and Control
Refinement of Reliability Grid Codes in the Provision of Ancillary Services
Torine R. Herstad, Jalal Kazempour, Lesia Mitridati et al. (+1 more)
Stochastic resources such as wind farms, electric vehicle aggregators, and demand-side assets are increasingly participating as reserve providers in ancillary service
markets. To manage delivery uncertainty, system operators impose minimum reliability thresholds on such providers. Energinet, the Danish transmission system operator (TSO), has pioneered this approach through the P90 requirement, requiring
stochastic providers to make accepted reserve capacity bids available with at least 90% probability. Yet this threshold is set by regulatory convention, not optimization: no existing framework treats it as a design variable or characterizes the cost-reliability trade-off it governs. This paper closes that gap. We develop a bilevel optimization framework in which the TSO in the upper level sets the reliability threshold endogenously while providers in the lower levels respond through reliability-constrained bidding, with chance constraints reformulated analytically using a Weibull tail distribution. Applied to the Nordic frequency containment reserve for disturbances (FCR-D)
market, the cost-optimal threshold lies below P90 in the studied cases, with cost reductions by up to 14.5% relative to the fixed standard. Dynamic hourly thresholds yield a further reduction of up to 2.4%, suggesting efficiency gains may increase in larger and more diverse reserve
markets.
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All authors Torine R. Herstad, Jalal Kazempour, Lesia Mitridati, Steven A. Gabriel
Signal Processing
Beyond Beamforming: Phase-and-Gain Channel Shaping via Rotatable Antenna Arrays
Xingxiang Peng, Qingqing Wu, Ziyuan Zheng et al. (+2 more)
This paper investigates geometry-reconfigurable transmission for multiuser communication systems enabled by a rotatable
antenna array. In contrast to conventional fixed arrays, the proposed architecture jointly exploits array pose adjustment and element-level boresight steering, thereby reshaping both the array-induced phase responses and the direction-dependent channel gains. We formulate a weighted sum-rate maximization problem that jointly optimizes the transmit beamformers, array pose, and element boresights under practical visibility and steering constraints. To reveal the underlying design principles, we first provide a
geometric interpretation via zero-forcing analysis, showing that the resulting rates stem from both channel-strength enhancement and spatial-separability improvement. Specifically, array-pose rotation improves inter-user channel orthogonality even with isotropic elements, whereas directional elements introduce a tradeoff between phase-based spatial separation and boresight-dependent gain
alignment. Motivated by these insights, we develop an efficient optimization framework that jointly coordinates transmit beamforming, array-pose adaptation, and element-boresight steering to exploit the geometry-induced phase-and-gain channel-shaping capability. Simulation results demonstrate that the proposed joint design outperforms fixed-array, pose-only, and boresight-only
benchmarks, with larger gains achieved under more directive element patterns and tighter boresight-steering constraints.
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All authors Xingxiang Peng, Qingqing Wu, Ziyuan Zheng, Wen Chen, Guangchi Zhang
Audio and Speech Processing
Spatial Speech Perception Systems: A Survey of Sound Source Localization, Directional Enhancement, and Speech Recognition
Pengyuan Shao and Dimitrios Kanoulas
Robust
speech understanding in real-world acoustic environments remains a fundamental challenge for intelligent auditory systems such as
robot audition, hearing aids, teleconferencing systems, smart speakers, and voice-controlled assistants. These systems must operate under background noise, reverberation, competing speakers, and dynamic acoustic conditions. Spatial
speech perception addresses this challenge by exploiting microphone-array information to localize, enhance, and interpret target
speech in complex acoustic scenes. This paper surveys spatial
speech perception systems with emphasis on the roles of sound source localization (SSL), directional
speech enhancement (DSE), and automatic
speech recognition (ASR), both individually and within integrated processing pipelines. We review classical signal-processing approaches and recent learning-based methods for microphone-array localization, beamforming, neural enhancement,
speech separation, and modern recognition architectures. Beyond component-level analysis, we discuss robustness to noise and reverberation, multi-speaker operation, real-time constraints, and computational efficiency. We also examine representative applications in
robot audition, hearing assistance, smart speakers, and teleconferencing, and identify open challenges and future directions toward robust, low-latency, and perception-aware
speech systems for complex acoustic environments.
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Audio and Speech Processing
Cross Domain Few-Shot Class-Incremental Audio Classification Via Adversarial Contrastive Learning
Yongjie Si, Yanxiong Li, Sen Huang et al. (+1 more)
Current Few-shot Class-incremental Audio Classification (FCAC) methods assume that samples of base and incremental classes are in the same domain (following the same distribution). However, there is generally a domain shift between the above two types of samples. In this paper, we explore the problem of Cross Domain FCAC where samples of base and incremental classes have domain shift. We propose a strategy of
adversarial contrastive training which enables the model to effectively classify samples of different classes from unseen domains. The model consists of an encoder and a classifier. The encoder is trained in base session but frozen in incremental sessions, whereas the classifier is trained in all sessions. Experiments are done on six pairs of cross-domain
datasets. Results show that our method exceeds state-of-the-art methods in average accuracy. The code is at https://github.com/YongjieSi/ACL.
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All authors Yongjie Si, Yanxiong Li, Sen Huang, Beibei Liu
Audio and Speech Processing · Cross-listed from cs.CL
Unlocking Speech-Text Compositional Powers: Instruction-Following Speech Language Models without Instruction Tuning
Congrui Du, Yang Zhang, Kaizhi Qian et al. (+1 more)
Instruction tuning for
speech language models (SLMs) is substantially more challenging than for text-based large
language models (LLMs), as it requires learning a new modality and a wide range of
speech-specific instructions in addition to those supported by text LLMs. Existing SLM training approaches largely replicate the text LLM training paradigm by synthesizing large-scale
speech pre-training and instruction-tuning
datasets. However, this strategy is difficult to scale, since
speech sequences are significantly longer than text sequences. In this paper, we propose SpeechCombine, an instruction-following
speech language model trained without any instruction tuning, using only a single round of
speech pre-training on 30k hours of data. Starting from a text LLM base model, we perform continuous pre-training on
speech utterances to obtain a
speech-adapted model, and then directly combine its weights with the weight difference between the instruction-tuned and base versions of the text LLM. Our results show that this simple combination strategy not only preserves the knowledge and capabilities of the original text LLM, but also effectively transfers them to the
speech domain. These findings suggest a new direction for SLM training that avoids reliance on massive
speech data.
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All authors Congrui Du, Yang Zhang, Kaizhi Qian, Shiyu Chang
Signal Processing
Fourier Preconditioning for Neural Feature Learning
Preston Pitzer, Anish Pradhan and Harpreet S. Dhillon
Mutual information (MI)-inspired feature learning techniques are capable of generating low-dimensional
embeddings that retain nonlinear dependence structures, but direct estimations of MI suffer from noisy probability distribution estimates in the low-data regime. The H-Score objective, computed from second-order statistics, provides a practical proxy metric for training feature extraction networks. We prove that H-Score is invariant to invertible transformations in the unrestricted functional setting, but becomes sensitive to input basis rotations under constrained approximation classes. Consequently, we study
unitary preconditioning for H-Score networks and show that selecting an appropriate basis rotation reduces finite-width truncation error by concentrating predictive dependence into fewer dominant modes. We identify the fast
Fourier transform (FFT) as an effective data-independent, low-cost preconditioner for approximately stationary processes, where spectral structure induces concentration of the cross-covariance singular value spectrum. We introduce training-free metrics based on spectral
entropy and cumulative dependence energy to quantify basis suitability and predict downstream inference gains prior to network training. Experiments across eight multivariate
datasets demonstrate that FFT preconditioning is particularly useful in resource-constrained regimes, achieving up to 50% normalized mean squared error (NMSE) reduction, while the proposed metrics correlate with observed performance gains and correctly identify cases where spectral preconditioning is detrimental.
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Systems and Control
Reference-Governed Distributed Safe Gradient Flow for Safe Optimal Output Agreement of Multi-Agent Systems
Zhanglin Shangguan, Wei Xiao, Bo Yang et al. (+1 more)
This paper studies safe optimal output agreement for nonlinear multi-
agent systems with output safety constraints. Existing safe feedback optimization methods often implement gradient-flow dynamics directly through the plant input, which may require high-order control barrier functions (HOCBFs). The resulting derivative-chain design is tuning-sensitive and can introduce additional
equilibrium conditions that alter the steady-state optimal solution. We propose a reference-governed two-layer architecture that separates lower-layer output regulation from upper-layer distributed optimization. The upper layer filters the reference gradient flow through first-order control barrier function constraints, which are easier to tune and preserve the steady-state optimality structure of the original agreement problem. The lower layer uses an internal-model-based output regulator with a reference-dependent Lyapunov function, from which dynamic safety margins (DSMs) are constructed to certify transient output safety. We prove forward invariance, optimal-solution preservation under DSM-compatibility conditions, and convergence via a Lyapunov small-gain argument. Simulations validate safe convergence, show advantages over HOCBF-based feedback optimization, and demonstrate adaptive tangential objective shaping for escaping spurious
equilibria induced by nonconvex obstacles.
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All authors Zhanglin Shangguan, Wei Xiao, Bo Yang, Xinping Guan
Signal Processing
Complexity-Scalable Direct Geolocation and Cancellation of Terrestrial GNSS Jammers: Single-Satellite and Multi-Antenna Experiments in Low Earth Orbit
Giacomo Pojani, Javier Tegedor, Joaquim Fortuny-Guasch et al. (+5 more)
Monitoring the
radio-frequency (RF) spectrum from space imposes demanding requirements to satellite platforms in terms of communication bandwidth and computational resources, which are necessary for the downlink, the storage, and the processing of high-throughput I/Q samples. This paper analyzes in depth the quasi-direct geolocation (QDG) as a technique to enable the exploitation of satellites of opportunity in low Earth orbit (LEO) to sense the spectrum in the bands of global
navigation satellite systems (GNSS). This is a technique of passive RF geolocation and consists of an ensemble of signal processing
algorithms, which compress the I/Q samples and process the compressed data through fast delay-Doppler shift matching and interferometry in a quantized time-frequency domain. These
algorithms speed up the exhaustive search of multiple RF sources in the position domain. The efficiency gain addresses the bottleneck that prevents the employment of satellites, which are limited in downlink capacity and on-board computational power. These satellites are usually constrained in size, weight and power (SWaP) and represent most of the spacecrafts in LEO. The ability to exploit assets as such for the geolocation of terrestrial GNSS jammers in near real time is instrumental the performance of a multi-constellation GNSS RFI monitoring system. The present work describes the mathematical framework and precision bounds, introduces single- and multi-
antenna uses cases, combines different compression methods, and evaluates the geolocation accuracy with real data. The I/Q samples were collected by a repurposed GNSS reflectometry (GNSS-R) satellite, OPS-SAT PRETTY, in a dedicated test session during Jammertest 2025. The experimental results demonstrate the capability to geolocate GNSS jammers with different signal-to-noise ratios (SNR) with extremely high compression ratios.
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All authors Giacomo Pojani, Javier Tegedor, Joaquim Fortuny-Guasch, Francesco Menzione, David Evans, Tim Oerther, Maximilian Henkel, Jonas Stene Lindbjor
Systems and Control
Influence of Radial Basis Activation Functions on Intelligent Controller for Robotic Manipulators
Kimmo Paldanius, Gabriel Da Silva Lima and Wallace Moreira Bessa
This paper presents an intelligent control framework for trajectory tracking of robotic manipulators using radial basis function (RBF) neural networks for online disturbance estimation. The proposed control structure combines model-based nonlinear control with an adaptive neural approximator that compensates for parametric uncertainties, friction, and unmodeled dynamics. A Lyapunov-based adaptation law with projection guarantees boundedness of the closed-loop signals and convergence of the tracking error to a compact region. The primary objective of this work is to investigate how the choice of activation function within the RBF network influences transient behavior, steady-state accuracy, and control smoothness. The controller is implemented on a robotic manipulator. Experimental results demonstrate that although stability is preserved for all kernels, activation function selection significantly affects adaptation dynamics and practical tracking performance. These findings demonstrate that activation function selection acts as a structural design parameter in intelligent control, directly shaping adaptation dynamics and practical closed-loop performance.
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Image and Video Processing · Cross-listed from cs.LG
Predicting Early Stages Of Alzheimer's Disease And Identifying Key Biomarkers Using Deep Artificial Neural Network And Ensemble Of Machine Learning Methodologies
Debopriya Ghosh
Alzheimers disease (AD) is a
brain disorder that develops slowly and mainly affects
memory, thinking,
language, and daily activities. It is one of the most common causes of dementia and creates many difficulties for patients as well as their families. In the early stage, the symptoms are often mild and may look like normal ageing. For this reason, many people are diagnosed late, when the disease has already progressed. At present, there is no complete cure for AD. Still, early detection can help doctors manage the condition better and take suitable steps at the right time. In this study, a machine learning model is proposed to detect the early stages of Alzheimers disease using clinical details, neuropsychological test scores, and neuroimaging-related measures. The data used in this work is collected from the Alzheimers Disease Neuroimaging Initiative (ADNI). As the
dataset has missing values, iterative imputation is applied to fill them. The
dataset also has class imbalance, which is handled using Borderline SVM-SMOTE. After that, feature selection is carried out using wrapper-based and embedded methods so that only important features are used for training. The selected features are divided into training and testing sets, and feature scaling is applied. A stacking ensemble model is developed using Logistic Regression, Extra Trees, Bagging KNN, and LightGBM as base classifiers. Along with this, an artificial neural network is also trained on the same
dataset. The performance of these models is compared using precision, recall, F1-score, and AUC-ROC. This study aims to find the best classifier and also identify important biomarkers that may help in the early diagnosis of Alzheimers disease.
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Systems and Control · Cross-listed from cs.LG
Adaptive Reparametrized Time for Score-Based Diffusion Sampling
Yilie Huang, Wenpin Tang and Xun Yu Zhou
We study timestep allocation for score-based
diffusion sampling, where a learned reverse-time dynamics is discretized on a finite grid. Uniform and hand-crafted schedules are standard choices, but they rely on fixed prescriptions and can therefore be suboptimal. To address this limitation, we propose Adaptive Reparameterized Time (ART), a continuous-time control formulation that learns a time change by treating the speed of the sampling clock as the control, so that a uniform grid on the learned clock induces adaptive timesteps in the original
diffusion time. Based on a leading-order Euler error surrogate, ART provides a principled objective for allocating timesteps along the sampling trajectory. To solve this deterministic control problem, we introduce ART-RL, an auxiliary randomized formulation with Gaussian policies that turns schedule learning into a continuous-time reinforcement learning problem. We prove that the randomized ART-RL formulation is equivalent to ART at the optimizer level, in the sense that its optimal Gaussian policy recovers the optimal ART time-warping rate through its mean. We further establish policy evaluation and policy improvement characterizations and derive trajectory-based moment identities that yield implementable actor–critic updates for learning the schedule. Across experiments ranging from controlled low-dimensional settings to image generation, ART-RL can be plugged into existing
diffusion samplers by changing only the timestep grid, consistently improving sample quality over strong baseline schedules at matched budgets while leaving the rest of the sampling pipeline unchanged. The learned schedules also exhibit broad generalization, transferring without retraining across sampling budgets,
datasets, solvers, pipelines, and representation spaces.
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Systems and Control
Reachability-Based Safe-Start Regions for Approach to a Tumbling Target with Rotating LOS Constraints
Omer Burak Iskender, Keck Voon Ling, Wee Seng Lim et al. (+1 more)
This paper presents a closed-form test that decides, before the maneuver begins, whether a chaser can reach and hold station at the hold point of a tumbling, uncooperative target inside a line-of-sight (LOS) corridor that turns with the target. A closed-loop controller cannot answer this question: a receding-horizon controller checks the corridor only over its prediction horizon, and near a tumbling target the corridor sweeps past faster than bounded thrust can follow, so a start that is feasible at the first step can become unrecoverable later. Today the only ways to know are to fly the controller in simulation or to compute a Hamilton–Jacobi reachable set, both too slow onboard. The test combines two criteria derived from bounded-thrust relative orbital dynamics: a directional erosion margin, the corridor margin that rotation-induced drift consumes before the thruster arrests it, and a synchronization radius, beyond which the apparent rotational velocity cannot be cancelled. Guidance pairs a three-regime tracking law with a receding-horizon quadratic program. Benchmarked against polytopic backward and forward reachable sets, Hamilton–Jacobi level sets and closed-loop Monte Carlo simulation, the test runs over two orders of magnitude faster than Hamilton–Jacobi and, over 500 closed-loop cases, predicts feasibility with 91% recall and 80% precision. The gap to Hamilton–Jacobi is structural, not a method error: reaching the hold point and co-rotating with it is a stronger requirement than arriving with arbitrary velocity, and the gap widens with tumble rate. The test therefore gives an onboard go/no-go answer where Hamilton–Jacobi reachability is too expensive.
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All authors Omer Burak Iskender, Keck Voon Ling, Wee Seng Lim, Erick Lansard
Image and Video Processing
Population-Scale Segmentation of Penile Tissue in DIXON MRI using Deep Learning for Quantitative Phenotyping in Male Reproductive Health
Jan Ernsting, Gunnar Paul Kordes, Nils Johannaber et al. (+5 more)
Penile measurement is clinically relevant across male reproductive and urogenital health, including conditions such as micropenis, congenital and endocrine disorders, and sexual or urinary dysfunction. However, quantitative assessment of penile size has relied mainly on external length or circumference measurements, which are difficult to standardize, sensitive to measurement conditions, and unable to capture the internal portion of the penis. MRI enables volumetric assessment of the whole penis in vivo, but automated
segmentation has not previously been established at population scale. Automated whole-organ volumetry would enable high-throughput phenotyping for multi-omics and clinical studies of male reproductive disease. Here, we present a deep learning framework for whole-penis
segmentation in multi-channel DIXON MRI. Using a newly curated expert-annotated training
dataset ($n = 145$ subjects; $13,050$ annotated slices) and a double-annotated independent test
benchmark ($n = 24$ subjects; $2,160$ double-annotated slices), we optimized a 3D nnU-Net architecture. The model achieved a 5-fold cross-validation Dice score of $0.90$ and performed at observer-level accuracy on the independent test set (Dice: $0.92$; Hausdorff distance: $3.58$). We deployed the model in $34,412$ UK Biobank participants, enabling automated quantification of total penile tissue, including both external and internal components. Longitudinal evaluation in 2,282 men demonstrated high inter-session reproducibility ($r = 0.87$). This framework establishes a reproducible and population-scalable method for MRI-based assessment of penile anatomy and provides an open technical resource for future studies in urological imaging and male reproductive health. The trained model weights will be publicly released.
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All authors Jan Ernsting, Gunnar Paul Kordes, Nils Johannaber, Lynn Ogoniak, Wolfgang Roll, Tim Hahn, Alexander Siegfried Busch, Benjamin Risse
Signal Processing
Coverage Analysis in Terahertz Clustered HetNets
Hadeel Obaid
Terahertz (THz) transmission technologies hold significant potential for enabling ultra-broadband, short-range communication in next-generation networks. Despite the vast bandwidth, THz signals suffer from limited transmission range and a feasible scenario is to deploy THz within clustered heterogeneous networks (HetNets) to enhance coverage. This paper investigates THz communication in clustered HetNets, leveraging
stochastic geometry for performance analysis. Specifically, we consider two tiers of macro base stations (MBS) and small base stations (SBS). The MBS tier is modeled as a Poisson Point Process (PPP), and both the SBS tier and users are modeled as a Poisson Cluster Process (PCP) to capture user clustering and network hotspots. We derive the analytical expressions for user association probabilities, the Laplace transform of interference, and the coverage probability. The derived coverage probability is validated through Monte Carlo simulation. The numerical results show that the coverage in THz PCP-HetNets is higher than that achieved in THz PPP HetNets. In addition, a moderate spatial spread of SBSs is beneficial for coverage.
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Audio and Speech Processing
An Efficient vLLM-Based Inference Pipeline for Unified Audio Understanding and Generation
Haoran Wang, Jinchuan Tian, Siddhant Arora et al. (+1 more)
While Large
Multimodal Models excel in comprehension, high-throughput inference engines lack native support for
multimodal generation. This is severe in
Speech Language Models, where generating multi-layered audio
tokens via decoupled AR+NAR or synchronous Multi-
Token Prediction (MTP) with delay-pattern interleaving conflicts with standard single-stream loops. We present a vLLM-based inference pipeline for unified
speech understanding and generation. We extend autoregressive decoding to natively execute delay-pattern de-interleaving and coordinated multi-stream sampling, integrating an on-GPU acoustic decoder for end-to-end waveform synthesis. Crucially, we overcome the shared intuition that Classifier-Free Guidance (CFG) halves throughput. By co-scheduling paired conditional and unconditional requests within a continuous batch, our CFG implementation sustains 80% of non-CFG throughput, absorbing dual-request and logit merging overheads. We open-source our framework.
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All authors Haoran Wang, Jinchuan Tian, Siddhant Arora, Shinji Watanabe