Search Results (1,522)

Hyperbolic interface problems are widely applied to model wave propagation and shock transmission across discontinuous media, such as acoustic waves in layered materials, seismic waves in the Earth’s crust, and stress or electromagnetic waves in composite structures. This study introduces a novel computational framework for hyperbolic interface problems, specifically designed to unify and extend the treatment of regular interfaces within partial differential equations. The proposed hybrid approach combined Haar wavelet-based spatial discretization with finite difference schemes for temporal integration. By employing truncated Haar series to approximate spatial derivatives and leveraging finite difference techniques for time evolution, the method delivers accurate solutions for both linear and nonlinear systems regardless of whether the governing coefficients are constant or spatially variable. In addressing linear problems, the resulting algebraic equations are solved efficiently using Gaussian elimination. For nonlinear formulations, the method incorporates a quasi-Newton linearization strategy, effectively transforming the system into a linear one. Extensive validation is performed through a suite of benchmark problems, with performance assessed via metrics including maximum absolute errors (MAEs), root mean square errors (RMSEs), and convergence behavior as a function of collocation point (CP) density. Numerical experiments highlight the method’s superior stability and accuracy, particularly in scenarios marked by discontinuities or sharp gradients in the solution. The approach proves especially effective in bridging inconsistencies between boundary and initial conditions, offering a robust alternative to existing techniques. Theoretical soundness, strong convergence properties, and comprehensive numerical validation collectively underscore the method’s reliability and adaptability across a broad spectrum of applications. Full article

A poly (acrylic acid–tannic acid) (PAA–TA) crosslinked composite is reported on for the first time as an aqueous binder for LiMn_0.6Fe_0.4PO₄ (LMFP) cathodes to suppress manganese dissolution. Benefiting from hydrogen bonding and chemical crosslinking, the PAA-TA binder constructs a robust three-dimensional network that strengthens the interfacial adhesion among active particles, conductive additives, and the current collector, stabilizing the LMFP crystal structure upon cycling. More importantly, this polymeric network effectively restrains manganese leaching, which is the major origin of the capacity fading of LMFP cathodes. Meanwhile, continuous electron and ion transport pathways are well established. The LMFP electrode with an optimized PA5TA1 binder delivers a reversible capacity of 112 mAh g⁻¹ at 5 C and retains 81.3% of its capacity after 300 cycles, outperforming the PVDF/LMFP electrode. Post–mortem analyses of cycled LMFP cathodes further confirm that there was substantially suppressed Mn²⁺ dissolution in the PAA–TA electrode, corroborating the structural integrity of the cathode–electrolyte interface. This crosslinked aqueous polymer provides a sustainable alternative to the PVDF binder for long–life LMFP cathodes. Full article

Compression packers are widely used in oil and gas well operations for zonal isolation, yet the large-deformation mechanical behavior of their rubber sealing elements lacks a closed-form analytical solution. This paper presents a complete theoretical analysis of the axisymmetric compression of an annular rubber cylinder based on the incompressible Mooney–Rivlin hyper-elastic model. The deformation process is divided into three successive stages: free expansion, casing-constrained deformation, and fully constrained deformation. Analytical expressions for the principal stretches, stress fields, and axial force are derived for each stage by integrating the radial equilibrium equation with proper treatment of the Lagrange multiplier. The frictionless analytical results are validated against axisymmetric finite element simulations, showing excellent agreement for all stress components. The applicability of the frictionless theory to frictional conditions is then examined. Results show that although friction introduces non-uniform axial deformation and end bulging, the average contact pressure on the rubber–mandrel interface agrees closely with the theoretical prediction, especially at higher axial forces (150–250 kN). A linear relationship between the average contact pressure and the axial force is confirmed, providing a simple design tool. The theoretical solution offers a computationally efficient alternative to finite element analysis for preliminary packer design and parametric studies. Full article

Economical operation of cascade pumping stations requires temporal feedback and spatial coordination, whereas a single day-ahead schedule cannot correct deviations arising during execution. This study develops a distributed multi-time-scale supervisory scheduling framework based on spatiotemporal decomposition. A convex parent model represents interval-average discharges, lumped canal-storage balances, delivery targets, tariff-based pumping cost, and station-level operating limits; within-reach hydraulic dynamics and unit-level electromechanical behavior are not resolved. Hourly day-ahead, 15 min intraday, and 5 min real-time models are linked through reference mapping, measured-state feedback, and remaining-delivery correction. The cascade is partitioned into station–canal subsystems, and the alternating direction method of multipliers coordinates local copies of each boundary flow without imposing equal adjacent-station discharges. In a deterministic five-station representative-day case, the proposed method reduced the absolute delivery error, flow-variation index, terminal canal-state deviation, and specific operating cost by 90.01%, 16.42%, 95.12%, and 3.42%, respectively, relative to decentralized local feedback without consensus exchange. Its delivered volume, specific energy, and specific operating cost differed from centralized multi-time-scale scheduling by only 0.006%, 0.006%, and 0.026%, respectively. All 313 distributed rolling problems converged, with mean intraday and real-time solution times of 6.583 s and 0.461 s. In constructed day-ahead cases containing 5–40 stations, the objective gap remained below 0.012% and the maximum interface mismatch below 1.0 × 10⁻⁴ m³ s⁻¹. These results support the numerical applicability of the coordination method to larger serial cascades sharing the same aggregate convex structure, but do not establish dynamic-hydraulic, unit-level, or field-scale validity. Full article

As the global community moves toward carbon neutrality by 2050, the iron and steel industries are facing significant pressure to reduce CO₂ emissions. Direct reduction processes using hydrogen-rich gases are emerging as a critical alternative to traditional blast furnace methods. This study investigates the reduction behavior of single hematite pellets using varying H₂-CO gas mixtures. Thermogravimetric analysis (TGA) was employed to measure reduction rates, while exhaust gas analysis helped elucidate the reaction mechanism. The results indicate that while higher temperatures and H₂ concentrations accelerate reduction, carbon deposition presents a significant challenge for real-time TGA measurements at lower temperatures. By focusing on the initial stage of reduction, this study effectively excluded the influence of carbon formation on the weight change. Under these controlled conditions, a topochemical receding interface model was found to be the most appropriate for determining rate constants and activation energies under different gas mixing ratios. The derived kinetic parameters and the understanding of H₂-CO reduction behavior provide essential fundamental data for optimizing the operating conditions of gas-based direct reduction processes. Full article

Matching patients to clinical trials with large language models is technically feasible, but the prevailing methodology fine-tunes commercial models through external interfaces, transmitting sensitive patient records to third parties, and the resulting screening decisions lack a record that an external auditor can verify. This paper proposes an end-to-end alternative combining privacy-preserving Federated Learning (FL) with a blockchain provenance layer settled on a Layer 2 rollup. On the learning side, we construct an extended benchmark of 3000 patient and trial pairs covering 12 medical conditions and compare FedAvg, FedProx, and FedDyn under simulated clinical heterogeneity with a worst-case label-skew stress client. With all models evaluated on one held-out test set at matched compute, FedDyn reaches an F1 score of 0.885 (0.883 ± 0.008 across five training seeds), matching the early-stopped centralized baseline of 0.878, while an extended 50-epoch centralized run reaches 0.945 (0.944 ± 0.023). Holdout experiments on unseen protocols and unseen conditions quantify the remaining generalization gap. A stratified membership inference evaluation with bootstrap confidence intervals provides preliminary evidence that federated training roughly halves the attacker’s membership advantage. The direction of this reduction is stable across all five seeds, although its confidence interval includes zero and attack area under the curve (AUC) values remain close to the 0.5 random-guessing level throughout. On the provenance side, every decision passes through a deterministic gate. Its evidence is AES-256-GCM-encrypted and stored off-chain on InterPlanetary File System (IPFS), while only cryptographic commitments are anchored by access-controlled smart contracts on the rollup, with a Merkle checkpoint on Ethereum Layer 1. On public test networks, Layer 2 settlement reduces the cost of anchoring each decision by a factor of approximately 53 relative to Layer 1, and the provenance of all 300 test-cohort decisions is independently re-verified end to end. Three Layer 2 hardening mechanisms, an L1 checkpoint, EIP-712 signed consent, and forced inclusion, are demonstrated at feasibility level. The implementation is publicly available on GitHub. Full article

Head gesture-based control using inertial measurement units (IMUs) provides an intuitive alternative to conventional human–machine interfaces for mobile and vehicle-mounted systems. However, gesture recognition reliability degrades significantly under terrain-induced vibration and mechanically dynamic operating conditions. This study investigates terrain-aware head gesture recognition through the integration of helmet-mounted IMU measurements and vehicle vibration sensing to improve discrimination between intentional gestures and non-intentional motion artefacts. Vehicle vibration data were collected from a patrol vehicle traversing the Ndumo Border Patrol route, characterised by variable terrain roughness and dynamic excitation profiles. Triaxial seat-rack acceleration data were acquired at 10 kHz, anti-alias filtered and down sampled to 100 Hz before being integrated with IMU-derived head motion measurements using both vibration-aware data augmentation and early sensor fusion strategies. FFT-based spectral processing and classification using a lightweight fully connected neural network (FCNN) were implemented using the Edge Impulse framework. Experimental evaluation was performed using temporally independent training and testing segments to reduce overlap leakage and ensure realistic generalisation assessment. Results demonstrate that terrain-informed sensing substantially improves operational robustness under mobile conditions. The early-fusion approach achieved 98.45% independent-test accuracy under float32 inference and maintained 90.02% accuracy after int8 quantization, corresponding to an accuracy reduction of 8.43 percentage points. In comparison, the Clean IMU and vibration-augmented models exhibited reductions of 20.13 and 27.02 percentage points, respectively, demonstrating greater sensitivity to quantization. The evaluated models also exhibited low inference latency and compact memory requirements, supporting their suitability for real-time edge implementation. These findings demonstrate that treating terrain vibration as contextual information, rather than solely as environmental noise, can improve the quantization robustness and deployment characteristics of IMU-based gesture-recognition systems intended for mechanically dynamic platforms. Full article

Risk assessment of engineered nanomaterials (ENMs) is essential for protecting human health and the environment. Traditional hazard assessments rely primarily on in vivo testing, which faces technical challenges in extrapolation validity, ethical dilemmas, and high costs. Machine learning (ML) models offer alternative approaches that are aligned with the 3R principles (Replacement, Reduction, and Refinement) for reducing animal use. ML methods help address the economic, ethical, and temporal limitations of traditional nanotoxicology while advancing mechanistic understanding. This review presents a cross-scale framework integrating nano–bio/nano–environmental interfaces, organ-specific toxicity, in vitro-to-in vivo extrapolation (IVIVE), interpretable ML, and regulatory translation. Future directions include building comprehensive databases to replace sparse literature data, developing ML models that bridge in vitro and in vivo nanotoxicity, incorporating co-exposure scenarios of nanomaterials and chemicals, and further exploring protein/lipid corona formation and structures. Full article

Skin-interfaced thermal sensors offer a promising, portable, and cost-effective alternative for continuous and noninvasive measurements of skin condition and blood flow. Skin condition, especially skin hydration, is reflected by the tissue thermal conductivity. Blood flow is characterized by the average flow velocity through blood vessels in skin. However, the measurement accuracy of tissue thermal conductivity and blood velocity is hindered by the coupled heat conduction and convection in the tissue containing blood vessels. To overcome this bottleneck for precise measurements of tissue thermal conductivity and blood velocity simultaneously, we design a skin-interfaced thermal sensor consisting of a resistive heater and three thermistors. The resistive heater with a diameter of 4 mm consumes a low power of 0.05 W. The three miniature thermistors measure the steady-state temperatures on skin at the middle location of the heater center, upstream flow location, and downstream flow location. Using finite element analysis (FEA) of heat transfer in vascular skin, we optimize the three-thermistor layout, placing the upstream and downstream thermistors 6.0 mm and 2.7 mm from the heater center, respectively. FEA results reveal that the middle-thermistor temperature is predominantly sensitive to tissue thermal conductivity with relatively low flow interference, whereas the temperature difference between upstream and downstream thermistors maintains high sensitivity to blood velocity, and is less affected by tissue thermal conductivity. With the FEA results, we implement a polynomial machine learning model and a physics-informed thermal-resistance reduced-order model to analyze the thermal sensor temperature measurements and jointly predict both quantities. The relative prediction errors are typically below 4% for thermal conductivity and 10% for blood velocity using the machine learning model, and below 1% and 8% using the reduced-order model. This work provides a framework for the development of skin-interfaced thermal sensors capable of intelligent and noninvasive skin and vascular assessment. Full article

The rapid growth of high-resolution 3D voxel datasets derived from LiDAR, BIM, and urban digital twin platforms has created new opportunities for volumetric environmental simulation. However, existing fire-spread models are often surface-based or computationally intensive for large-scale 3D applications, motivating the investigation of efficient voxel-native alternatives. This study presents a pilot investigation of a physics-based, GPU-accelerated framework for rapid 3D fire-spread simulation in wildland–urban interface (WUI) environments. Fire propagation is represented through simplified formulations of conduction, radiation, and wind-driven convection on a structured voxel grid, with combustion behavior parameterized using fuel and material properties. The framework is not intended to replace high-fidelity computational fluid dynamics (CFD) models, but rather to provide a computationally efficient approach for rapid evaluation of fire-spread scenarios in large 3D urban environments. A voxel-native parallel memory layout and stencil-based computational scheme enable efficient neighbor access and GPU-parallel updates. The framework is demonstrated using a voxelized model of Liverpool, NSW, Australia, and its computational performance is evaluated on both local GPU and high-performance computing (HPC) platforms. The results demonstrate predictable runtime scaling and practical performance for domains exceeding one million active burnable voxels. An initial cross-model comparison with the FDS CSIRO scenario further demonstrates substantial spatial agreement while identifying remaining differences in burned area. The results demonstrate the feasibility of the framework for rapid urban-scale 3D fire-spread evaluation, with potential future applications in emergency response and time-critical decision support following further calibration and validation. Full article

We investigate the magnetization reversal of a ferromagnetic layer by an applied in-plane charge current in SOT-MRAM devices utilizing the spin Hall effect (SHE) as well as the SHE and an applied in-plane external magnetic field. We also consider the case of a strong field-like torque generated by other SOT mechanisms, such as Rashba-type interface effects. By deriving the steady-state solutions of the driven system and evaluating their stability, we identify two distinct mechanisms that govern deterministic switching. In the first-oscillation-driven mechanism, the magnetization is pushed past an unstable steady-state by the initial deviation following the current onset, after which it relaxes towards an alternative steady-state branch in the opposite hemisphere. As lower damping produces a larger initial oscillation amplitude at a given current, the critical current depends on the Gilbert damping constant $\alpha$. We show that the usual damping-independent critical current expression is recovered in the overdamped regime with $\alpha \ge 1$. In the instability-driven mechanism, activated by field-like torque, even a small initial oscillation grows until the equator is crossed and the magnetization ends in the opposite hemisphere. The critical switching current is the minimum of both mechanisms. Thus, the steady-state landscape reveals distinct current regimes, identifying optimal operating regimes for perpendicular reversal. Full article

Both bulk solution properties and the molecular organisation of the electrode/solution interface may influence the kinetics and reversibility of an electrode process. In this study, the effects of acetonitrile (ACN) and 2-thiouracil (2-TU) in an acidic perchlorate medium on the electroreduction of Bi(III) ions were investigated. A cyclically renewable liquid silver amalgam film electrode (R-AgLAFE) was used as the working electrode as an alternative to classical mercury electrodes. Direct current polarography (DC), square-wave voltammetry (SWV), cyclic voltammetry (CV), and differential capacitance measurements were used. Increasing the ACN content from 0_(v/v) to 50%_(v/v) decreased the current response, D_ox, and effective kinetic parameters α and k_s,app while increasing ΔE_p, indicating decreased apparent reversibility of the electrode process. The addition of 2-TU caused a pronounced increase in the SWV peak current and a decrease in the difference between the anodic and cathodic peak potentials. In the 50%_(v/v) ACN solution, the accelerating effect was weakest at the highest 2-TU concentration. The differential capacitance measurements provided evidence consistent with significant reorganisation of the interfacial layer. Overall, the observed acceleration associated with 2-TU is consistent with adsorption-dependent interfacial effects and the possible participation of labile Bi(III)–2-TU-associated species in the near-electrode region. Full article

This state-of-the-art review critically evaluates shotcrete for concrete rehabilitation using an application-based framework covering buildings, bridges, tunnels and underground works, hydraulic and marine structures, and industrial facilities. The review synthesizes deterioration mechanisms, substrate and interface conditions, material and process variables, mechanical and durability performance, quality control, and alternative repair systems. Recent studies are integrated with established guidance and case histories, and quantitative evidence tables are used to facilitate cross-study comparison. Across structural applications, the shotcrete–substrate interface is identified as a critical factor governing rehabilitation performance, with surface condition, moisture state, shrinkage, curing, and environmental exposure affecting bond and durability. The synthesis further demonstrates that performance requirements vary by application, including section restoration, confinement, bond, and durability in buildings and bridges; early-age support, toughness, and residual capacity in tunnels; and low permeability and abrasion/erosion resistance in hydraulic and marine structures. Five research questions are proposed to address key uncertainties in interface behavior, durability, field performance, material development, and quality assurance. The resulting framework provides a systematic basis for evaluating shotcrete rehabilitation strategies and identifying priorities for future research. Full article

This work presents a spatial multi-feed beam steering reflectarray concept intended for compact small satellite payloads with adapted field of view (FoV) coverage. Unlike conventional reflectarray beam steering approaches based on tunable unit cells or mechanical reconfiguration, the proposed approach exploits the controlled displacement of the phase center of a digital planar feed array to illuminate a passive reflectarray surface from different spatial positions, enabling beam steering without tunable unit cells or mechanical reconfiguration. First, the beam steering mechanism is analyzed through the phase gradients induced by feed displacement, including the impact of amplitude illumination and incidence angle-dependent unit cell response. Then, the concept is experimentally validated at 30 GHz using a developed reflectarray and a 2 × 2 patch array feed repositioned over a multi-position interface to emulate overlapping subarrays of a virtual 4 × 4 feed array. The measured radiation patterns show good agreement with simulations, confirming the predicted beam pointing trends with measured gains between 26.57 and 27.91 dBi for the evaluated subgroups. Finally, a mission-oriented architecture for the UPMSat-4 scenario is analyzed, considering a reflectarray surface up to 600 mm × 400 mm integrated into solar panels and a 16-element linear array feed. The results demonstrate the feasibility of generating a linear multibeam FoV, achieving beam overlap and a minimum carrier-to-noise ratio (C/N) of approximately 32 dB in the considered link budget scenario. The proposed architecture provides a scalable and low-complexity alternative for flexible smallsat antenna payloads. Full article

Steel storage tanks are erected on site by multi-cylinder hydraulic lifting, conventionally from one power unit feeding all cylinders through a flow divider. Decentralized alternatives have not been evaluated for this task, and modularity in fluid power is rarely quantified. A ten-cylinder device was analyzed as a centralized (C1) and a modular (C3) variant with a servomotor-driven pump at each cylinder; both were decomposed into five functional modules and compared through a directed design structure matrix (DSM). External dependencies per module fell by 38.6% and mean interface complexity by 30.9%, against only 11.1% for interfaces per module: interfaces were thinned, not removed. Internal cohesion rose from 0.583 to 0.805; the total risk priority number, an ordinal expert-assigned indicator, fell from 2253 to 760. C1 was characterized from documentation and was not tested experimentally; a three-module prototype at a length scale of 0.31 was run through sixteen series: open and closed loop, both directions, four disturbance configurations. In open loop, the error left the ±2% band in every series; in closed loop, it stayed inside the band in lifting and over the last 91–92% of stroke in lowering, cutting the drift rate by one to two orders of magnitude. The structural gain corresponds to removing the hydraulic installation and the flow divider, which dominate both the open-loop drift and the failure-mode ranking; the modular device costs about 58% more. Full article