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Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.

At least 361 records · Page 20Linked to original sources

arXiv2026

Neumann eigenvalues of isosceles triangles: monotonicity and asymptotics

We prove Laugesen and Siudeja's conjecture on Neumann eigenvalues of isosceles triangles. After multiplication by the squared diameter, the first positive symmetric eigenvalue increases strictly with the apex angle $θ$, while the first antisymmetric eigenvalue decreases strictly up to the equilateral triangle and increases strictly thereafter. \rev{The proof combines a slice-average estimate of directional energies with the explicit equilateral eigenfunction.} A quadratic correction across slices also gives a two-term expansion for every fixed positive spectral index $k$ as $θ\downarrow0$, with relative correction $θ^2/6$ and remainder $O_k(θ^4)$.

math.SP↗

arXiv2026

Reconfigurable bus-based quantum router for modular superconducting processors

Scaling superconducting quantum processors requires interconnects that provide both non-local connectivity and parallel entangling operations. Nearest-neighbour couplings require distant interactions to be routed through SWAP networks, increasing the native two-qubit-gate count and potentially extending the circuit critical path. Here we introduce a bus-based reconfigurable quantum router for modular superconducting processors. Flux-tunable SQUID couplers selectively connect interface qubits to two shared buses, allowing destructive interference to suppress idle interactions while supporting two disjoint controlled-$Z$ (CZ) gates in parallel. Full-system Hamiltonian simulations yield parallel-gate errors at the level of $10^{-3}$, and open-system analysis identifies the coherence requirements for high-fidelity operation. We further assess the circuit-level consequences using hardware-aware compilation and resource-constrained scheduling. For 36-qubit quantum Fourier transform (QFT), QAOA-MaxCut and random-pairing circuits, the router reduces the median SWAP count by up to $34\%$ and the native CZ count by up to $20\%$ relative to a matched two-dimensional grid. End-to-end depth reduction is circuit dependent, reaching $20\%$ for QAOA-MaxCut but remaining negligible for the QFT despite its lower gate count. These results show that enhanced connectivity and schedulable parallelism provide distinct benefits, establishing the router as a compiler-visible hardware resource for modular superconducting quantum processors.

quant-ph↗

arXiv2026

Efficient Record-and-Replay Arithmetic for Quantum Elliptic-Curve Point Addition

We study reversible secp256k1 point-addition circuits developed through ECDSA.Fail for Shor's elliptic-curve discrete-logarithm algorithm. Two complementary constructions improve record-and-replay GCD arithmetic: Jump-2 groups binary-GCD steps and compresses their decisions using base-5 encoding, while ping-pong uses fixed register alternation and one-bit decisions to avoid full-width comparisons and data-dependent swaps. Fused replay combines doubling and signed addition into one modular correction. Both constructions support quantum-addressed window selection with measurement-based lookup cleanup. We compare three circuits on 100,000 fresh inputs across nine lookup-table configurations. A separately tested repair uses 1,419 qubits and 1.356 million mean executed Toffolis, with no detected failures on another 100,000 inputs. Structured supported-input counterexamples remain, so these tests do not establish all-input correctness. We also provide conditional coherent-error analysis and reversible safegcd comparisons. Under the stated window allowance, repaired-circuit resources lie below Google's low-gate caps and Schrottenloher's low-gate estimates, but differing accounting and correctness evidence preclude formal dominance. The results concern individual window-selected additions, not complete Shor computations.

quant-ph↗

arXiv2026

Direct and Indirect Data-Driven Control with Prior Information about the Equilibrium Manifold

By hinging on the assumption that a system to be controlled is fully unknown, many data-driven control approaches do not leverage available or readily inferable priors. In contrast to this viewpoint, this paper analyzes the impact of using the system's equilibrium subspace to inform direct and indirect linear quadratic regulation. For the indirect case, we show how including a constraint on the equilibrium subspace in the identification problem changes the statistical properties of the learned model. In particular, we show that enforcing consistency with respect to the equilibrium subspace leads to a reduction in the estimator variance that, in turn, enhances model-based control performance. In the direct case, we show how this prior can be leveraged to gain insight into the controlled system without requiring an explicit identification step. These results are supported by both numerical and experimental evidence, showcasing the advantages of explicitly leveraging the equilibrium manifold as a prior in data-driven control.

eess.SY↗

arXiv2026

Wave-driven propulsion of a flexible raft

Inertial propulsion in fluids generally arises from an unbalanced flux of momentum. For the case of wave-driven propulsion, momentum is transported away from an oscillating raft in the form of self-excited surface waves. While this mechanism has previously been analyzed for rigid rafts, the role of flexibility has yet to be investigated. In this work, we develop a fluid-structure interaction model for a periodically driven two-dimensional flexible raft resting at the free surface of a fluid. The raft is modeled as an Euler--Bernoulli beam and is coupled to a weakly dissipative quasi-potential model of the fluid beneath. Varying the flexural stiffness and forcing position reveals new features associated with the introduction of flexibility, including the possibilities of thrust enhancement and reversal. By projecting the raft response onto its free rigid-body and elastic modes, the fluid loading can be represented as a modal impedance, informing a computationally efficient reduced-order model. Analysis of the modal response and its symmetries facilitates physical interpretation of our key findings. For a uniform raft, excitation of any single mode in isolation is incapable of producing a net thrust, and thus efficient wave propulsion requires a blend of interfering modes with appropriately coordinated amplitudes and phases.

physics.flu-dyn↗

arXiv2026

Global modal/non-modal analysis of high-enthalpy Martian entry vehicles

We analyze laminar-to-turbulent transition over a blunt capsule representative of Martian entry at Mach 26 using global modal and transient-growth analyses about a thermochemical base flow characteristic of high-altitude entry conditions. Across the Reynolds-number range considered ($Re_\infty = 10^4$--$10^6$), the axisymmetric global eigenspectrum remains stable, ruling out temporally unstable axisymmetric global modes as a viable route to transition. The flow nevertheless supports strong transient growth concentrated in the shear--entropy layer generated by bow-shock curvature. Energy-budget analysis reveals a two-stage process: Reynolds-stress production in the mean shear first amplifies kinetic disturbances, which then generate entropy fluctuations as they traverse the strong base-flow entropy gradient. The optimal gain scales linearly with the Reynolds number based on the capsule nose radius, whereas boundary-layer-localized disturbances become competitive at the highest Reynolds numbers examined. These results identify shear--entropy-layer transient growth as a plausible linear pathway for seeding transition in high-enthalpy blunt-entry vehicles.

physics.flu-dyn↗

arXiv2026

Characterizing LLM-Based Family Education through the Lens of Activity Theory: A Scoping Review of the HCI Literature

Large language models (LLMs) are increasingly involved in family education, yet HCI has not systematically explained the educational interactions that emerge around them. This scoping review analyzes 53 HCI studies from 6,540 records across 19 venues. Using activity theory and AODM, it relates participants and educational objects to mediation, labour, and rules. We find that the literature centers on child--parent interaction and on language, AI literacy, and relational learning. The introduction of LLMs enabled conversational, embodied, and spatial systems to generate support from the context of an unfolding interaction. LLMs redistributed educational labour, while family and institutional rules left parents and professionals responsible for interpreting outputs and deciding how they entered practice. Evidence across families and educational purposes remains limited, especially on sustained personalization, repair labour, and how families negotiate authority and rules. The review offers a framework explaining how LLM capabilities become organized through family participation.

cs.HC↗

arXiv2026

Fly, Drive, Reconfigure: A Modular Reconfigurable Aerial-Ground Platform for Field Operations

Heterogeneous robot teams distribute complementary capabilities across specialized agents, but their physical roles and capacities typically remain fixed throughout a mission. We present HARP, a Heterogeneous Aerial Robotic modules Platform in which independently deployable aerial robots physically reconfigure to compose their capabilities for field operations. HARP comprises sensor-equipped scouts, flydrive rover modules, and task-specific payload modules. Scouts map the environment and inform an energy-aware planner that jointly selects routes and air-ground mobility modes. Rover and payload modules fly independently across terrain that constrains ground travel, then autonomously assemble into a cooperative ground vehicle for energy-efficient payload transport. Motivated by environmental sampling in remote and difficult-to-traverse regions, we evaluate HARP through field experiments spanning sensing, planning, reconfiguration, airground mobility, payload transport, and task execution. We further conduct module-level deployment tests on the Greenland Ice Sheet toward future autonomous missions. HARP demonstrates how heterogeneous robot teams can adapt not only their actions, but also how their physical capabilities are composed during a mission.

cs.RO↗

arXiv2026

Learned-projector QAOA for hierarchical optimization

Many optimization problems reveal inexpensive structural information before requiring costly final evaluation, whereas the conventional quantum approximate optimization algorithm (QAOA) applies a single aggregate objective throughout. We introduce the learned-projector quantum alternating operator ansatz (LP-QAOA), a multistage protocol that freezes optimized circuits and uses their output states to define later projector mixers. We prove a stability theorem for LP-QAOA that bounds the propagation of approximation errors through successive frozen stages. Our analysis also shows how learned-projector mixing avoids the high-order tunnelling suppression of local mixers. We conduct state-vector simulations on block-constrained spin tiling (BCST) instances, where LP-QAOA achieves higher probabilities of sampling the optimum, lower estimated logical-resource requirements, and better trainability than the tested baselines. A supporting stochastic block model experiment extends LP-QAOA to optimization problems with soft hierarchical structure. Our results highlight the potential of LP-QAOA to improve variational quantum optimization by exploiting hierarchical problem structure.

quant-ph↗

arXiv2026

Central stars of newly discovered infrared nebulae: eruptive Be stars PY Gem and HD253659

The presence of a nebula around massive hot stars often works as an indicator that the object is either in an advanced evolutionary stage or a rare product of close binary interaction. Here, we focus on two Be stars - PY Gem and HD253659 - whose nebulae were detected with the Wide-field Infrared Survey Explorer. We estimated their basic physical parameters from modelling the spectral energy distribution and examined their variability. We combined archival photometric data from several ground-based survey telescopes and from the Transiting Exoplanet Survey Satellite (TESS) with our own data from dedicated multi-colour photometric and spectroscopic monitoring, and concluded that, despite having similar stellar properties, the photometric variability of the two objects is strikingly different. For HD253659 we detected continuous eruptive variability and a major outburst that took place between 2016 and 2022 along with numerous flicker events seen in the TESS data. HD253659 also exhibits loop-like behaviour in the colour-magnitude diagram, consistent with build-up and dissipation phases of a circumstellar disk seen close to pole-on. In contrast, during the past ~20 years PY Gem has lost its eruptive variability and shows only small-amplitude p and g-mode pulsations classifying PY Gem as βCephei hybrid pulsator. An incoherent low-frequency signal is identified as a Štefl frequency, which seems to be supported by the cyclic variation of the emission-line profiles. Detailed analysis of these stars indicates that both objects are inconsistent with evolved massive stars, and that the origin of their nebulae is more likely linked to the physics of the Be phenomenon.

astro-ph.SR↗

arXiv2026

Study of Chromospheric Global-Scale Flows using Local Correlation Tracking Across the past 10 Solar Cycles

Global-scale solar surface flows, including differential rotation and meridional circulation, provide key observational constraints on the solar dynamo. We investigate these flows using local correlation tracking (LCT) of chromospheric intensity structures in digitized \ion{Ca}{2}~K observations from the Kodaikanal Solar Observatory covering Solar Cycles (SC) 14 to 23 (1907 -- 2007). The most valuable data coverage are from cycles 14 to 19 for two reasons: (1) it provided record for early cycles that are not commonly available; (2) it had much better duty cycle than the data of cycles 20-23, therefore the measurements had much less errors. On the other hand, the information loss in cycles 20-23 are compensated by other modern space observations. The recovered differential rotation shows relatively small cycle-to-cycle variations and remains close to the Howard reference profile. Recurring zonal-flow residual bands at low and middle latitudes are broadly associated with the activity belts during the well-sampled SC~15--19. The meridional flow is predominantly poleward in the earlier record and exhibits larger relative cycle-to-cycle variations and uncertainties. Incomplete coverage of SC~14 and sparse sampling during SC~21--23 limit detailed comparisons to the better-covered SC~15--20. Compared with its immediate successor SC~19, the strongest cycle in the record, SC~18 exhibits a stronger and continuous northern poleward meridional branch, peaking two to three years before its sunspot maximum. SC~19 shows a minor enhancement that peaks earlier prior to its own maximum. An independent comparison using PSPT observations yields a full-period correlation of $r=0.91$ between the LCT and SDO/HMI meridional-flow profiles. These results extend the observational context for solar-cycle-related flows over a century and motivate further refinement through data-driven reconstruction.

astro-ph.SR↗

arXiv2026

Influence of chemical vapor deposition conditions on N incorporation ratio on vicinal 4H-SiC(000-1) surface: Ab Initio-based approach

In experimental studies, increasing the ratio of source gases (C3H8/SiH4; C/Si ratio) for chemical vapor deposition (CVD) causes the growth rate to increase monotonically, and nitrogen incorporation tends to decrease accordingly; however, a unique phenomenon has been observed in which nitrogen incorporation increases discontinuously in the range of C/Si ratio between 1.0 and 1.5. This phenomenon is specific to the vicinal 4H-SiC(000-1) C-face and is not observed on the vicinal 4H-SiC(0001) Si-face. In this study, N incorporation behavior on a vicinal C-face during CVD is investigated using an ab initio-based approach. The calculation results suggest that when C/Si ratio is less than 1.0, the Si-terminated step edge is stable, whereas when C/Si ratio exceeds 1.0, the existence probability of the C-H-terminated step edge, where the N substitution energy is lower than in the former case, increases sharply. This change in the step-edge state across C/Si = 1.0 is thought to be the cause of the discontinuous increase in N incorporation.

cond-mat.mtrl-sci↗

arXiv2026

Trident Tableaux for Tree-Child Networks with One Reticulation Node: A Bijection with Two-Wall Tableaux

Motivated by a word encoding of tree-child networks, we introduce trident tableaux, which are Young tableaux with a unique three-cell column satisfying certain conditions on successors. We construct a bijection between trident tableaux with $n+1$ columns and two-wall tableaux with $n$ columns, that is, two-row fillings with two designated columns in which vertical order is not imposed. The bijection matches the three-part decompositions of the two classes and shows that each class has cardinality $n(n+1)C_n/2$, where $C_n$ is the $n$-th Catalan number. In particular, it gives a trident-tableau interpretation of a shifted form of OEIS A002457. As a consequence, we obtain an exact enumeration of tree-child networks with one reticulation node that contain a trident, and show that their proportion among all tree-child networks with one reticulation node tends to $1/8$ as the number of leaves tends to infinity.

math.CO↗

arXiv2026

Yes, $(2K_2, K_4)$-free graphs are recolorable

We prove that every $(2K_2,K_4)$-free graph is recolorable. Equivalently, for every such graph $G$ and every $\ell\geq χ(G)+1$, the reconfiguration graph of proper $\ell$-colorings of $G$, in which two colorings are adjacent if they differ on exactly one vertex, is connected. This resolves the final remaining open case in the classification of recolorable $(F_1,F_2)$-free graphs when $F_1$ and $F_2$ have at most four vertices.

math.CO↗

arXiv2026

Towards clinical adoption of voice and speech as measures of health: the need for harmonization

Speech and voice are multidimensional signals that capture both communicative intent and underlying physiological processes, providing a unique, non-invasive window into health. Analyzing these signals has the potential to yield digital biomarkers that (i) provide scalable, objective measurement tools for research and clinical care and (ii) reflect the presence or progression of diverse conditions, including neurological, psychiatric, respiratory, and cardiovascular disorders. Realizing this promise, however, requires the field to overcome pervasive reproducibility and generalizability issues due to heterogeneous data collection, processing, and analysis practices. A major source of this heterogeneity is how underlying acoustic measures themselves are defined and computed. In this paper, we outline key considerations across the speech biomarker discovery lifecycle, from data collection through machine learning modeling to clinical interpretation, needed to achieve reliable, reproducible, and clinically translatable results. Chief among these is the need for harmonization efforts to start from common, precisely specified measure definitions. As a first step, we therefore provide definitions, physiological correlates, and computational implementations for a minimal, clinically interpretable set of core speech measures spanning respiration, phonation, articulation, and fluency. We close by discussing ongoing standardization efforts and the open challenges that remain in advancing the adoption of speech- and voice-based digital biomarkers.

cs.ET↗

arXiv2026

GeoDose-CP: Graph-Local Conformal Inference for Continuous-Treatment Earth Observation

Reliable intervention-oriented uncertainty quantification from Earth observation (EO) remains challenging when continuous treatment shifts, spatial dependence, limited support, and satellite-outcome uncertainty must be addressed simultaneously. Existing causal, conformal, and spatial approaches address parts of this problem, but their direct combination does not generally recover the appropriate interventional reference law because candidate reassignment jointly alters treatment likelihood, standardized residuals, and graph-dependent residual likelihood. This study presents GeoDose-CP, a support-aware conformal framework for localized stochastic potential outcomes under continuous or mixed continuous-atomic treatment. Its central methodological contribution is a graph-local target-orbit law that jointly represents intervention-induced treatment shift, the inverse outcome-scale Jacobian, and spatial residual dependence. The framework further provides exact weighted candidate inversion, a scalable sparse approximation with explicit discrepancy accounting, and refusal under inadequate support. Evaluation used controlled known-truth experiments, MineDoseBench, treatment-density sensitivity analysis, external conformal comparators, and a multi-mine New South Wales (NSW) study. In MineDoseBench, GeoDose-CP achieved mean selective coverage of 0.9692 across 27 configurations and a minimum local q0.05 of 0.8951; exact-sparse auditing produced nine inclusion disagreements over 2,700 targets. In the NSW study, the absence of an auditable longitudinal rehabilitation treatment rendered treatment-dependent inference nonoperational rather than forcing inference through a proxy exposure.

stat.AP↗

arXiv2026

Specification-Driven Benchmarking for Automated Program Repair From Static Corpora to Executable Specifications

Automated Program Repair (APR) benchmarks have traditionally been constructed as static datasets whose characteristics are inherited from the defects they contain. While this paradigm has enabled decades of progress, finite corpora provide limited experimental control, become increasingly susceptible to contamination as they are reused, and cannot be systematically regenerated or adapted as evaluation requirements evolve. We propose specification-driven benchmarking, a paradigm in which benchmarks are defined by executable specifications and realized through benchmark generation. The specification explicitly declares the intended properties of the benchmark (including program context, fault taxonomy, difficulty, validation strategy, and corpus constraints) while a generation pipeline realizes those requirements through independent generation, validation, and corpus management components. We develop the conceptual foundations of this approach by introducing a taxonomy of benchmark specification dimensions, establishing how each specification dimension maps to deterministic architectural responsibilities, and arguing that independent validation is a structural requirement for trustworthy benchmark generation. An end-to-end example illustrates how specification choices propagate through the pipeline to produce benchmark instances whose properties are independently verifiable. By treating the benchmark as an executable specification rather than a static dataset, the proposed paradigm shifts benchmark construction from artifact curation to declarative experimental design.

cs.SE↗

arXiv2026

Characterization and Active Control of Position-Dependent Timing Dynamics in Superconducting Strip Detectors

Superconducting strip single-photon detectors (SSPDs) have emerged as scalable, wide-strip variants of traditional nanowire counterparts. Despite practical advantages including improved optical fill factors and enhanced signal-to-noise ratios the fundamental detection physics governing these micro-scale geometries remains largely unexplored. Here, we investigate the underlying photoresponse of a 20 um-wide tungsten silicide SSPD, demonstrating a slew-rate-corrected timing jitter of 13.2 ps at 532 nm and 20.5 ps at 1550 nm, alongside saturated internal detection efficiency up to 1550 nm. Using focused free-space optical scanning, we reveal that detector timing jitter is strongly influenced by a spatially dependent slew rate between edge and center absorption events. To mitigate this impact, we utilize a parallel superconducting rail architecture to actively redistribute supercurrent. This in-situ tuning minimizes the latency mismatch and mitigates thermally activated intrinsic dark counts, extending the device's ability to operate at higher temperatures. Finally, comparing these dynamics with time-dependent Ginzburg-Landau (TDGL) modeling elucidates the physical origins of the position-dependent photoresponse, highlighting how superconducting rails or specialized readout electronics can mitigate negative impacts on timing jitter.

physics.ins-det↗