Systems and Control
Assessing performance tradeoffs in hierarchical organizations using a diffusive coupling model
Lorenzo Zino, Mengbin Ye and Brian D.O. Anderson
We study a continuous-time dynamical system of nodes diffusively coupled over a hierarchical network to examine the efficiency and performance tradeoffs that organizations, teams, and command and control units face while achieving coordination and sharing information across layers. Specifically, after defining a network structure that captures real-world features of hierarchical organizations, we use linear systems theory and perturbation theory to characterize the rate of convergence to a consensus state, and how effectively information can propagate through the network, depending on the breadth of the organization and the strength of inter-layer communication. Interestingly, our analytical insights highlight a fundamental performance tradeoff. Namely, networks that favor fast coordination will have decreased ability to share information that is generated in the lower layers of the organization and is to be passed up the hierarchy. Numerical results validate and extend our theoretical results.
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Systems and Control
Mean-field control barrier functions for stochastic multi-agent systems
Cinzia Tomaselli, Gian Carlo Maffettone, Samy Wu Fung et al. (+2 more)
Many applications involving multi-
agent systems require fulfilling safety constraints. Control barrier functions offer a systematic framework to enforce forward invariance of safety sets. Recent work extended this paradigm to mean-field scenarios, where the number of
agents is large enough to make density-space descriptions a reasonable workaround for the curse of dimensionality. However, an open gap in the recent literature concerns the development of mean-field control barrier functions for Fokker-Planck (advection-
diffusion) equations. In this work, we address this gap, enabling safe mean-field control of
agents with
stochastic microscopic dynamics. We provide bounded stability guarantees under safety corrections and corroborate our results through numerical simulations in two representative scenarios, coverage and shepherding control of multi-
agent systems.
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All authors Cinzia Tomaselli, Gian Carlo Maffettone, Samy Wu Fung, Levon Nurbekyan, Mario di Bernardo
Signal Processing
Secure Cell-Free Massive MIMO ISAC Systems: Joint AP Selection and Power Allocation Against Eavesdropping
Ruiguang Wang, Takumi Takahashi and Hideki Ochiai
This paper investigates a
cell-free massive multiple-input-multiple-output (CF-mMIMO) integrated sensing and communication (
ISAC) system that addresses the critical challenge of information leakage to potential eavesdroppers located within sensing zones. A novel access point (AP) selection strategy is proposed, which partitions the distributed APs into two functional groups: communication APs (C-APs), dedicated exclusively to data transmission, and sensing APs (S-APs), responsible for target detection and eavesdropper suppression. Closed-form expressions for the achievable communication rate, eavesdropping rate, and mainlobe-to-average-sidelobe ratio (MASR) are derived to evaluate system performance. Two complementary optimization problems are formulated using the successive convex approximation (SCA): (i) maximizing user rates under security constraints and (ii) minimizing eavesdropping rates while satisfying quality of service (QoS) requirements. The proposed joint optimization framework determines the optimal AP operational modes and power allocation across communication and sensing links. Extensive numerical results validate the theoretical analysis and demonstrate significant performance gains, revealing inherent trade-offs among communication efficiency, sensing accuracy, and security. These insights offer practical guidelines for designing secure CF-mMIMO
ISAC systems.
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Signal Processing
Enabling 6G Wireless Communications: UWB Characterization of Corridors within the H-Band
Juan E. Galeote-Cazorla, Alejandro Ramírez-Arroyo, Mauricio Rodríguez et al. (+2 more)
Future sixth-generation of wireless system is expected to provide data-rates in the order of 1 Tbps and latencies below 1 ms. Among others, one of the most promising strategies to meet these requirements is to operate at higher frequencies than millimeter wave bands: the THz bands. Nevertheless, because of the higher losses and the detriment of classical propagation mechanisms, deploying systems operating at these frequencies becomes a real challenge. Consequently, short-range scenarios are of special interest since these effects of THz bands can be managed. This work conducts an extensive campaign within corridors at frequencies within the H-band in the range from 250 GHz to 330 GHz. For the first time in literature, an ultra wideband of 80 GHz is studied simultaneously. Large scale effects are assessed by estimating and modeling path gain. The path gain exponent varies between -2.1 and -1.6, which is explained by a guiding effect also observed at millimeter wave bands. Small scale effects are also evaluated in terms of parameters such as rice $K$-factor, root mean squared delay spread and coherence bandwidth. Additionally, an analytical approximation based on the classical N-rays model is proposed obtaining an accurate representation of the wireless channel which is coherent with the empirical analysis. The full analysis reveals the suitability of these THz bands for deploying point-to-point links due to the predominance of the line-of-sight contribution respect to the reflected components.
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All authors Juan E. Galeote-Cazorla, Alejandro Ramírez-Arroyo, Mauricio Rodríguez, Reinaldo Valenzuela, Juan F. Valenzuela-Valdés
Audio and Speech Processing · Cross-listed from cs.CL
DiscoPhon: Benchmarking the Unsupervised Discovery of Phoneme Inventories With Discrete Speech Units
Maxime Poli, Manel Khentout, Angelo Ortiz Tandazo et al. (+3 more)
We introduce DiscoPhon, a
multilingual benchmark for evaluating unsupervised phoneme discovery from discrete
speech units. DiscoPhon covers 6 dev and 6 test
languages, chosen to span a wide range of phonemic contrasts. Given only 10 hours of
speech in a previously unseen
language, systems must produce discrete units that are mapped to a predefined phoneme inventory, through either a many-to-one or a one-to-one assignment. The resulting sequences are evaluated for unit quality, recognition and
segmentation. We provide four pretrained
multilingual HuBERT and SpidR baselines, and show that phonemic information is available enough in current models for derived units to correlate well with phonemes, though with variations across
languages.
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All authors Maxime Poli, Manel Khentout, Angelo Ortiz Tandazo, Ewan Dunbar, Emmanuel Chemla, Emmanuel Dupoux
Systems and Control · Cross-listed from cs.AR
WarPGNN: A Parametric Thermal Warpage Analysis Framework with Physics-aware Graph Neural Network
Haotian Lu, Jincong Lu, Sachin Sachdeva et al. (+1 more)
With the advent of system-in-package (SiP) chiplet-based design and heterogeneous 2.5D/3D integration, thermal-induced warpage has become a critical reliability concern. While conventional numerical approaches can deliver highly accurate results, they often incur prohibitively high computational costs, limiting their scalability for complex chiplet-package systems. In this paper, we present WarPGNN, an efficient and accurate parametric thermal warpage analysis framework powered by Graph Neural Networks (GNNs). By operating directly on graphs constructed from the floorplans, WarPGNN enables fast warpage-aware floorplan exploration and exhibits strong transferability across diverse package configurations. Our method first encodes multi-die floorplans into reduced Transitive Closure Graphs (rTCGs), then a Graph Convolution Network (GCN)-based encoder extracts hierarchical structural features, followed by a U-Net inspired decoder that reconstructs warpage maps from graph feature
embeddings. Furthermore, to address the long-tailed pattern of warpage data distribution, we developed a physics-informed loss and revised a message-passing encoder based on Graph Isomorphic Network (GIN) that further enhance learning performance for extreme cases and expressiveness of graph
embeddings. Numerical results show that WarPGNN achieves more than 205.91x speedup compared with the 2-D efficient FEM-based method and over 119766.64x acceleration with 3-D FEM method COMSOL, respectively, while maintaining comparable accuracy at only 1.26% full-scale normalized RMSE and 2.21% warpage value error. Compared with recent DeepONet-based model, our method achieved comparable prediction accuracy and inference speedup with 3.4x lower training time. In addition, WarPGNN demonstrates remarkable transferability on unseen
datasets with up to 3.69% normalized RMSE and similar runtime.
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All authors Haotian Lu, Jincong Lu, Sachin Sachdeva, Sheldon X.-D. Tan
Image and Video Processing
UEPS: Robust and Efficient MRI Reconstruction
Xiang Zhou, Hong Shang, Zijian Zhan et al. (+3 more)
Deep unrolled models (DUM) have become the state-of-the-art for accelerated MRI reconstruction, yet their robustness under domain shift remains a critical barrier to clinical adoption. In this work, we identify coil sensitivity map (CSM) estimation as the primary bottleneck limiting generalization. To address this, we propose UEPS, a novel DUM architecture featuring three key designs: (i) an Unrolled Expanded (UE) design that eliminates CSM dependency by reconstructing each coil independently; (ii) progressive resolution, which leverages k-space-to-image mapping for efficient coarse-to-fine refinement; and (iii) sparse
attention tailored to MRI's 1D undersampling nature. These physics-grounded designs enable gains in robustness and computational efficiency. We construct a large-scale zero-shot transfer
benchmark comprising 10 out-of-distribution (OOD) test sets spanning diverse clinical shifts, anatomy, view, contrast, vendor, field strength, and coil configurations. Extensive experiments demonstrate that UEPS consistently and substantially outperforms existing DUM, end-to-end,
diffusion, and untrained methods across all OOD tests, achieving state-of-the-art robustness with low-latency inference suitable for real-time deployment.
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All authors Xiang Zhou, Hong Shang, Zijian Zhan, Tianyu He, Jintao Meng, Dong Liang
Signal Processing · Cross-listed from cs.CE
Damage identification using noisy frequency response functions based on topology optimization
Akira Saito, Ryo Sugai, Zhongxu Wang et al. (+1 more)
This paper proposes a robust damage identification method using noisy frequency response functions (FRFs) and
topology optimization. We formulate the damage identification problem as an inverse problem of generating the damage
topology of the structure from measured dynamic responses of the structure to given external dynamic loading. The method is based on the minimization of the objective function representing errors between measured FRFs of the structure obtained by experimental modal analysis, and those obtained by harmonic response analysis using finite element analysis. In the minimization process, material distribution, or the
topology of the structure is varied and the optimal damage
topology is identified as regions with no material assigned as a result of the minimization using the solid isotropic material with penalization (SIMP). In order to overcome the problems caused by the ill-posedness of the inverse problem, it is proposed that the least absolute shrinkage and selection operator (Lasso) regularization, or the penalization to the L1 norm of the design variable be applied to the original objective function. By applying Lasso regularization, the method is expected not only to eliminate spurious damaged regions but also to minimize the effect of measurement noises. This paper first presents the mathematical background and its numerical implementation of the proposed methodology. The method is then applied to the identification of a damage of cantilevered plates. The FRFs were experimentally obtained and the proposed method is applied. It is shown that the method successfully identifies the damage.
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All authors Akira Saito, Ryo Sugai, Zhongxu Wang, Hidetaka Saomoto
Systems and Control · Cross-listed from cs.LG
HEP Statistical Inference for UAV Fault Detection: CLs, LRT, and SBI Applied to Blade Damage
Khushiyant
This paper transfers three statistical methods from particle physics to multirotor propeller fault detection: the likelihood ratio test (LRT) for binary detection, the CLs modified frequentist method for false alarm rate control, and sequential neural posterior estimation (SNPE) for quantitative fault characterization. Operating on spectral features tied to rotor harmonic physics, the system returns three outputs: binary detection, controlled false alarm rates, and calibrated posteriors over fault severity and motor location. On
UAV-FD, a hexarotor
dataset of 18 real flights with 5% and 10% blade damage, leave-one-flight-out cross-validation gives AUC 0.862 +/- 0.007 (95% CI: 0.849–0.876), outperforming CUSUM (0.708 +/- 0.010), autoencoder (0.753 +/- 0.009), and LSTM autoencoder (0.551). At 5% false alarm rate the system detects 93% of significant and 81% of subtle blade damage. On PADRE, a quadrotor platform, AUC reaches 0.986 after refitting only the generative models. SNPE gives a full posterior over fault severity (90% credible interval coverage 92–100%, MAE 0.012), so the output includes uncertainty rather than just a point estimate or fault flag. Per-flight sequential detection achieves 100% fault detection with 94% overall accuracy.
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Image and Video Processing
SCISSR: Scribble-Conditioned Interactive Surgical Segmentation and Refinement
Haonan Ping, Jian Jiang, Cheng Yuan et al. (+3 more)
Accurate
segmentation of tissues and instruments in
surgical scenes is annotation-intensive due to irregular shapes, thin structures, specularities, and frequent occlusions. While SAM models support point, box, and mask
prompts, points are often too sparse and boxes too coarse to localize such challenging targets. We present SCISSR, a scribble-promptable framework for interactive
surgical scene
segmentation. It introduces a lightweight Scribble Encoder that converts freehand scribbles into dense
prompt embeddings compatible with the mask decoder, enabling iterative refinement for a target object by drawing corrective strokes on error regions. Because all added modules (the Scribble Encoder, Spatial Gated Fusion, and LoRA adapters) interact with the backbone only through its standard
embedding interfaces, the framework is not tied to a single model: we build on SAM 2 in this work, yet the same components transfer to other
prompt-driven
segmentation architectures such as SAM 3 without structural modification. To preserve pre-trained capabilities, we train only these lightweight additions while keeping the remaining backbone frozen. Experiments on EndoVis 2018 demonstrate strong in-domain performance, while evaluation on the out-of-distribution CholecSeg8k further confirms robustness across
surgical domains. SCISSR achieves 95.41% Dice on EndoVis 2018 with five interaction rounds and 96.30% Dice on CholecSeg8k with three interaction rounds, outperforming iterative point prompting on both
benchmarks.
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All authors Haonan Ping, Jian Jiang, Cheng Yuan, Qizhen Sun, Lv Wu, Yutong Ban
Audio and Speech Processing
ARTT: Augmented Reverberant-Target Training for Unsupervised Monaural Speech Dereverberation
Siqi Song, Fulin Wu and Zhong-Qiu Wang
Due to the absence of clean reference signals and spatial cues, monaural unsupervised
speech dereverberation is a challenging ill-posed inverse problem. To realize it, we propose augmented reverberant-target training (ARTT), which consists of two stages. In the first stage, reverberant-target training (RTT) is proposed to first further reverberate the observed reverberant mixture signal, and then train a deep neural network (DNN) to recover the observed reverberant mixture via discriminative training. Although the target signal to fit is reverberant, we find that the resulting DNN can effectively reduce reverberation. In the second stage, an online self-
distillation mechanism based on the mean-teacher
algorithm is proposed to further improve dereverberation. Evaluation results demonstrate that ARTT achieves strong unsupervised dereverberation performance, significantly outperforming previous baselines.
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Systems and Control · Cross-listed from math.OC
Fundamental Limits for Sensor-Based Control via the Gibbs Variational Principle
Vincent Pacelli and Evangelos A. Theodorou
Fundamental limits on the performance of feedback controllers are essential for benchmarking
algorithms, guiding sensor selection, and certifying task feasibility – yet few general-purpose tools exist for computing them. Existing information-theoretic approaches overestimate the information a sensor must provide by evaluating it against the uncontrolled system, producing bounds that degrade precisely when feedback is most valuable. We derive a lower bound on the minimum expected cost of any causal feedback controller under partial observations by applying the Gibbs variational principle to the joint path measure over states and observations. The bound applies to nonlinear, nonholonomic, and hybrid dynamics with unbounded costs and admits a self-consistent refinement: any good controller concentrates the state, which limits the information the sensor can extract, which tightens the bound. The resulting fixed-point equation has a unique solution computable by bisection, and we provide conditions under which the free energy minimization is provably convex, yielding a certifiably correct numerical bound. On a scalar LQG problem the self-consistent bound captures over 80% of the known optimal cost at moderate sensor noise, and on a nonlinear Dubins car tracking problem it remains informative across all noise levels where a bound using the uncontrolled state distribution is vacuous.
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Systems and Control
Generalizations of Backup Control Barrier Functions: Expansion and Adaptation for Input-Bounded Safety-Critical Control
David E. J. van Wijk, Dohyun Lee, Ersin Das et al. (+3 more)
Guaranteeing the safety of nonlinear systems with bounded inputs remains a key challenge in safe autonomy. Backup control barrier functions (bCBFs) provide a powerful mechanism for constructing controlled invariant sets by propagating trajectories under a pre-verified backup controller to a forward invariant backup set. While effective, the standard bCBF method utilizes the same backup controller for both set expansion and safety certification, which can restrict the expanded safe set and lead to conservative dynamic behavior. In this study, we generalize the bCBF framework by separating the set-expanding controller from the verified backup controller, thereby enabling a broader class of expansion strategies while preserving formal safety guarantees. We establish sufficient conditions for forward invariance of the resulting implicit safe set and show how the generalized construction recovers existing bCBF methods as special cases. Moreover, we extend the proposed framework to parameterized controller families, enabling online adaptation of the expansion controller while maintaining safety guarantees in the presence of input bounds.
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All authors David E. J. van Wijk, Dohyun Lee, Ersin Das, Tamas G. Molnar, Aaron D. Ames, Joel W. Burdick
Systems and Control
Deceiving Flexibility: A Stealthy False Data Injection Model in Vehicle-to-Grid Coordination
Kaan T. Gun, Xiaozhe Wang and Danial Jafarigiv
Electric vehicles (EVs) in Vehicle-to-Grid (V2G) systems act as distributed energy resources that support grid stability. Centralized coordination such as the extended State Space Model (eSSM) enhances scalability and estimation efficiency but may introduce new cyber-attack surfaces. This paper presents a stealthy False Data Injection Attack (FDIA) targeting eSSM-based V2G coordination. Unlike prior studies that assume attackers can disrupt physical charging or discharging processes, we consider an adversary who compromises only a subset of EVs, and limiting their influence to the manipulation of reported State of Charge (SoC) and power measurements. By doing so, the attacker can deceive the operator's perception of fleet flexibility while remaining consistent with model-based expectations, thus evading anomaly detection. Numerical simulations show that the proposed stealthy FDIA can deteriorate grid frequency stability even without direct access to control infrastructure. These findings highlight the need for enhanced detection and mitigation mechanisms tailored to aggregated V2G frameworks
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Systems and Control
Topological Obstructions to the Existence of Control Barrier Functions
Massimiliano de Sa and Aaron D. Ames
In 1983, Brockett developed a topological necessary condition for the existence of continuous, asymptotically stabilizing control laws. Building upon recent work on necessary conditions for set stabilization, we develop Brockett-like necessary conditions for the existence of control barrier functions (CBFs). By leveraging the unique geometry of CBF safe sets, we provide simple and self-contained derivations of necessary conditions for the existence of CBFs and their safe, continuous controllers. We demonstrate the application of these conditions to instructive examples and kinematic nonholonomic systems, and discuss their relationship to Brockett's necessary condition.
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Systems and Control · Cross-listed from cs.GT
Interleaved Information Structures in Dynamic Games: A General Framework with Application to the Linear-Quadratic Case
Janani S K, Kushagra Gupta, Ufuk Topcu et al. (+1 more)
A fundamental problem in noncooperative dynamic game theory is the computation of Nash
equilibria under different information structures, which specify the information available to each
agent during decision-making. Prior work has extensively studied
equilibrium solutions for two canonical information structures: feedback, where
agents observe the current state at each time, and open-loop, where
agents only observe the initial state. However, these paradigms are often too restrictive to capture realistic settings exhibiting interleaved information structures, in which each
agent observes only a subset of other
agents at every timestep. To date, there is no systematic framework for modeling and solving dynamic games under arbitrary interleaved information structures. To this end, we make two main contributions. First, we introduce a method to model deterministic dynamic games with arbitrary interleaved information structures as Mathematical Program Networks (MPNs), where the network structure encodes the informational dependencies between
agents. Second, for linear-quadratic (LQ) dynamic games, we leverage the MPN formulation to develop a systematic procedure for deriving Riccati-like equations that characterize Nash
equilibria. Finally, we illustrate our approach through an example involving three
agents exhibiting a cyclic information structure.
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All authors Janani S K, Kushagra Gupta, Ufuk Topcu, David Fridovich-Keil
Systems and Control
A Distributionally Robust Optimal Control Approach for Differentially Private Dynamical Systems
Yeongjun Jang, Kaoru Teranishi and Junsoo Kim
In this paper, we develop a distributionally robust optimal control approach for differentially private dynamical systems, enabling a plant to securely outsource control computation to an untrusted remote server. We consider a plant that ensures differential
privacy of its state trajectory by injecting calibrated noise into its output measurements. Unlike prior works, we assume that the server only has access to an ambiguity set consisting of admissible noise distributions, rather than the exact distribution. To account for this uncertainty, the server formulates a distributionally robust optimal control problem to minimize the worst-case expected cost over all admissible noise distributions. However, the formulated problem is computationally intractable due to the nonconvexity of the ambiguity set. To overcome this, we relax it into a convex Kullback–Leibler divergence ball, so that the reformulated problem admits a tractable closed-form solution.
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