Search Results (32,237)

Agentic shopping assistants increasingly move beyond recommending products to executing actions in users’ workflows (e.g., adding items to cart, applying coupons, selecting shipping). This shift from advice to delegation raises questions about appropriate reliance, perceived control, and how interface cues support oversight when systems can act. We report a laboratory eye-tracking experiment using a chat-only e-commerce prototype in a mixed 2 × 2 design: action autonomy varied within participants (recommend-only vs. act-on-behalf, with undo/edit), and transparency cues varied between participants (minimal statements vs. preview + rationale describing what will happen and why). Three standardized shopping tasks were completed by 72 participants. Results included behavioral logs (task time, overrides), areas-of-interest (AOI)-based eye-tracking (chat attention and verification indicators), and post-task self-reports (trust, control, uneasiness, perceived transparency). Act-on-behalf autonomy reduced completion time, but it also increased unease, decreased trust and perceived control, and increased the likelihood of an override, suggesting a trade-off between efficiency and oversight. The autonomy-related penalties for trust and perceived control under act-on-behalf execution were lessened by preview + rationale transparency, which additionally enhanced perceived transparency, trust, and unease. This mechanism coincided with eye-tracking: transparency decreased verification latency during agent actions and redirected attention toward information supplied by assistants. Transparency did not reliably reduce overrides, suggesting that minimal effective transparency can streamline supervision and improve evaluations without eliminating corrective behavior. Full article

Simulator-based digital twins are widely used in robotics education and industrial development to accelerate prototyping and enable safe experimentation. However, they often hide implementation details that are essential for understanding, diagnosing, and correcting system failures. This paper introduces a technology-independent model-based design framework that provides students with full visibility of the computational mechanisms underlying robotic controllers while remaining feasible within a 150-h undergraduate course. The approach relies on representing controller behavior using networks of Extended Finite State Machines (EFSMs) and their stacked extension (EFS2M), which unify all abstraction levels of the control architecture—from low-level reactive behaviors to high-level deliberation—under a single formal model. A structured programming template ensures traceable, optimization-free software synthesis, facilitating debugging and enabling self-diagnosis of design flaws. The framework includes real-time synchronized simulation, transparent switching between virtual and physical robots, and a smart data logger that captures meaningful events for model updating and error detection. Integrated into the Intelligent Robots course, the system supports topics such as kinematics, control, perception, and simultaneous localization and mapping (SLAM) while avoiding dependency on specific middleware such as Robot Operating System (ROS) 2. Over three academic years, students reported positive hands-on experiences, strong adaptability to diverse modeling approaches, and consistently high survey ratings reflecting the course’s overall quality. The proposed environment thus offers an effective methodology for teaching end-to-end robot controller design through transparent, simulation-driven digital twins. Full article

Background: Intermaxillary elastics are widely used in orthodontics to deliver controlled forces for malocclusion correction, aiding in the correction of anteroposterior, vertical, or transverse problems. Despite their clinical relevance, comprehensive mechanical characterization remains limited. Objective: This study aimed to evaluate the mechanical properties of nine types of intermaxillary elastics available on the market to guide evidence-based clinical selection. Methods: Elastics were tested under uniaxial tensile loading following ISO 37:2011 and ISO 21606:2007, with six replicates per type. Load–displacement and stress–strain responses were analyzed, measuring peak force, elongation at rupture, work-to-rupture, and specific rupture work. Non-linear behavior was modeled using cubic polynomial regression, and normalized stress–strain curves enabled intrinsic material comparisons. One-way ANOVA with post-hoc tests assessed differences among elastics. Results: All elastics displayed characteristic non-linear elastomeric responses. Functional grouping distinguished short-displacement/high-stiffness, intermediate-displacement/moderate-stiffness, and long-displacement/high-capacity bands. Work-to-rupture, specific rupture work, and normalized stress–strain metrics varied significantly, reflecting differences in energy absorption and force delivery (p < 0.05). Conclusions: Mechanical characterization, including energy-based descriptors and normalized stress–strain analysis, supports informed elastic selection, enhancing orthodontic treatment predictability and patient safety. Full article

Extrusion-based three-dimensional (3D) bioprinting has enabled the fabrication of complex, cell-laden constructs; however, process parameter selection remains largely empirical and system-specific. As biofabrication workflows scale in complexity and translational ambition, trial-and-error optimization increasingly limits reproducibility, transferability, and informed decision-making. In this work, a formal, optimization-oriented design framework is proposed to structure extrusion-based bioprinting as a constrained, multivariable design problem. Rather than introducing a system-specific predictive model, the framework organizes process parameters, material descriptors, scaffold architecture, and biological feasibility into a unified formulation based on objective functions and admissible constraints. Symbolic coupling relationships are employed to make parameter dependencies, trade-offs, and constraint interactions explicit without imposing restrictive assumptions on material behavior or biological response. A demonstrative computational case study is presented to illustrate how qualitative predictive reasoning emerges through constraint-driven design space analysis and multi-objective considerations. The framework reveals how feasible operating regions are shaped by competing biological, mechanical, and manufacturing limitations, emphasizing robustness-aware parameter selection over isolated optimization. The proposed approach is intended as a transferable methodological foundation that supports structured reasoning, experimental planning, and future integration with numerical models, data-driven tools, and closed-loop biofabrication systems. Full article

The oxygen evolution reaction (OER) is the rate-limiting step in alkaline water electrolysis for hydrogen production. Owing to their earth abundance and high intrinsic activity, transition metal-based catalysts (TMBCs) have emerged as promising alternatives to noble-metal catalysts, with defect engineering recognized as an effective strategy for enhancing OER performance. This review systematically summarizes recent advances in regulating alkaline OER activity of TMBCs through vacancy defects, including anion vacancies, cation vacancies, and divacancies. First, the alkaline OER mechanism, key performance evaluation parameters, and activity descriptors are briefly introduced. The formation mechanisms and regulation strategies of different vacancy types are discussed, with emphasis on how vacancy defects enhance OER performance by modulating electronic structures, optimizing active sites, and tuning adsorption–desorption behaviors of reaction intermediates. In addition, the advantages and application scenarios of various characterization techniques for vacancy defects are summarized. Finally, current challenges are identified, and future research directions are proposed. This review provides theoretical and practical references for the rational design of high-performance transition metal-based OER catalysts and the large-scale advancement of alkaline water electrolysis for hydrogen production. Full article

Adiabatic shear banding (ASB) is a critical failure mechanism in titanium alloys subjected to high-strain-rate deformation, and its initiation is strongly influenced by the initial crystallographic texture. The dynamic response and ASB sensitivity of extruded and annealed Ti-6Al-4V (TC4) alloy rods were investigated under dynamic compression of cubic specimens along the extrusion direction (ED) and the transverse direction (TD) at a strain rate of 2500 s⁻¹. Split Hopkinson pressure bar (SHPB) tests combined with digital image correlation (DIC) were employed to obtain the stress–strain response and the evolution of strain localization. A dislocation density-based crystal plasticity finite element model (CPFEM), incorporating the measured texture, was established to elucidate the correlation between texture and ASB behavior. The experimental results show that TD specimens exhibit a yield strength approximately 100 MPa higher than that of ED specimens, while both orientations display comparable post-yield hardening behavior. ASB initiation occurs earlier in TD (compressive strain ~0.13) than in ED (~0.23), indicating greater ASB sensitivity in the TD orientation. The CPFEM successfully reproduces the directional stress–strain responses and the observed localization morphology, enabling mechanistic interpretation in terms of slip activity and thermomechanical coupling. The simulations indicate that ED loading is dominated by prismatic ⟨a⟩ slip, resulting in lower flow stress and more dispersed strain localization. In contrast, TD loading is governed primarily by pyramidal ⟨c + a⟩ slip, leading to elevated flow stress and intensified localization. The higher ASB sensitivity in the TD orientation is therefore attributed to texture-controlled slip-mode partitioning, enhanced thermomechanical coupling, and a more concentrated crystallographic orientation distribution that facilitates intergranular slip transfer. These findings provide guidance for tailoring microtexture to mitigate dynamic failure in titanium alloys subjected to high-strain-rate loading. Full article

Duplex-phase low-density steels are attracting interest for lightweight structural applications, as reducing vehicle mass is an effective route to lower fuel consumption and emissions. This review summarizes recent progress in alloy design, processing, microstructure control, and performance of duplex-phase low-density steels. The roles of major alloying elements are discussed in terms of phase stability and precipitation tendency, followed by an overview of typical processing routes from melting to hot and cold rolling and subsequent heat treatments used to tailor phase fractions and defect structures. Strengthening mechanisms are reviewed with emphasis on precipitation control, including the beneficial contribution of fine intragranular κ′ precipitates and the ductility penalty associated with coarse intergranular κ* films, as well as the use of B2-based particles for high specific strength. Deformation behavior is then discussed in terms of transformation-/twinning-induced plasticity (TRIP/TWIP), planar versus wavy slip, and strain partitioning between ferrite and austenite. Finally, key challenges are outlined, including quantitative interface-based mechanism description, gaps in service property data, stable industrial production and compositional uniformity, and the development of forming and welding windows for engineering implementation. Full article

The one-dimensional Bin Packing Problem (1D-BPP) is a well-known NP-hard grouping problem characterized by high structural complexity and broad practical relevance. Among the metaheuristic approaches proposed for this problem, the Grouping Genetic Algorithm with Controlled Gene Transmission (GGA-CGT) has shown remarkable performance. In this work, an Adaptive Grouping Genetic Algorithm with Controlled Gene Transmission based on Fullness and Item Strategies (AGGA-CGT-FIS) is presented. This approach extends the original GGA-CGT by integrating domain-guided crossover mechanisms and adaptive parameter control schemes. The proposed algorithm incorporates a novel gene-level crossover operator, termed Fullness–Items Gene-Level Crossover 1 (FI-GLX-1). This operator exploits structural information from the solutions through Fullness- and Item-based ordering and transmission strategies. In addition, adaptive control schemes are introduced for key evolutionary parameters associated with crossover and mutation. These mechanisms allow the algorithm to dynamically adjust its behavior according to feedback extracted from the search process, resulting in a fully adaptive variant of the GGA-CGT. The effectiveness of AGGA-CGT-FIS is evaluated using two benchmark sets for the 1D-BPP: the classic and the BPP$v_u\_c$ instances. The proposed approach is compared against the baseline GGA-CGT using the original Gene-Level Crossover (GLX) operator. Experimental results show improvements in solution quality and convergence behavior, supported by statistical analyses that confirm the significance of the observed performance differences. Full article

The “direct method” is commonly employed to establish analytical models for assessing the stress state of curved beam bridges during incremental walking-launch construction. However, this approach often involves cumbersome mathematical derivations for curved elements and entails high computational costs. To overcome these limitations, this study proposes a “straight-line substitution method” and examines its applicability for analyzing the mechanical behavior of a composite system consisting of steel box girders and steel guide beams during the curved beam walking-launch process. Using a curved river-crossing bridge as a case study, finite element analysis (FEA) is conducted to compare the mechanical responses of the composite system under various loading conditions obtained from the proposed method and the conventional direct method. Furthermore, a parameter analysis is performed to investigate the influence of variations in beam height and width on the consistency between the two methods. The results demonstrate that the straight-line substitution method yields computational outcomes highly consistent with those of the direct method across different beam heights and widths. Moreover, the proposed method exhibits superior modeling efficiency compared to the direct method. Full article

In this study, we propose a homotopy-inspired prompt obfuscation framework to enhance understanding of security and safety vulnerabilities in Large Language Models (LLMs). By systematically applying carefully engineered prompts, we demonstrate how latent model behaviors can be influenced in unexpected ways. Our experiments encompassed 15,732 prompts, including 10,000 high-priority cases, across LLama, Deepseek, KIMI for code generation, and Claude to verify. The results reveal critical insights into current LLM safeguards, highlighting the need for more robust defense mechanisms, reliable detection strategies, and improved resilience. Importantly, this work provides a principled framework for analyzing and mitigating potential weaknesses, with the goal of advancing safe, responsible, and trustworthy AI technologies. Full article

Nickel-titanium (NiTi) alloys are attractive for functional and biomedical applications due to their shape memory effect, superelasticity, and favorable corrosion resistance and biocompatibility. In this work, the influence of strut size on the compressive response of laser-based powder bed fusion (PBF-LB/M) fabricated NiTi ortho-octahedral porous scaffolds was systematically investigated using combined experiments and finite element simulations. Four scaffold designs with identical unit-cell size (2 mm) but different strut sizes (280, 320, 360, and 400 μm) were fabricated, and their forming quality and deformation behaviors were examined. The as-built scaffolds exhibited high geometric fidelity to the CAD models and stable manufacturability across the investigated parameter range. Quasi-static compression tests revealed a typical three-stage response (linear-elastic regime, plateau/collapse regime, and densification), with both elastic modulus and compressive strength increasing markedly with strut size. Specifically, the modulus increased from 1.17 to 4.28 GPa and the compressive strength increased from 155 to 564 MPa as the strut size increased from 280 to 400 μm. A pronounced oscillatory plateau was observed for the 280 μm scaffolds, indicating progressive layer-by-layer collapse, whereas larger struts promoted a shear-band-dominated failure mode characterized by an approximately 45° fracture zone. Explicit quasi-static simulations reproduced the experimentally observed collapse sequence and demonstrated that stress preferentially concentrates at nodal junctions, with load transfer dominated by struts aligned with the loading direction. The agreement between experiments and simulations confirms the predictive capability of the proposed modeling framework and provides mechanistic insights into geometry-controlled failure. These findings establish a structure-property-failure relationship for PBF-LB/M-fabricated NiTi octahedral scaffolds and offer practical guidance for tailoring stiffness, strength, and collapse mode through strut-size design. Full article

Coal gangue represents the predominant solid waste in the coal industry and poses significant risks to both the ecological environment and human health. It has been demonstrated that recycling it in building materials effectively reduces stockpiling, mitigates environmental harm, and minimizes heavy metal leaching. However, a comprehensive review systematically focusing on the recycling of coal gangue and the behavior of its associated heavy metals in building materials is still lacking. This work introduces the physicochemical properties and environmental hazards of coal gangue, including spontaneous combustion, land occupation, and pollution risks. It also summarizes the leaching patterns, speciation, and immobilization mechanisms of heavy metals such as Cr, Cu, and Pb in gangue-based building materials, and reviews adsorption behaviors, solidification pathways, and microstructural interactions at the molecular scale. Despite ongoing efforts, over five billion tons of coal gangue remain accumulated in China, with secondary pollution from heavy metals continuing to pose serious concerns. To address these challenges, recommendations are proposed for establishing standardized leaching evaluation methods, and a novel approach for transitioning from heavy metal solidification to active utilization is introduced. This review aims to provide strategic direction for the green and sustainable recycling of coal gangue. Full article

The physiological efficacy of plant-based matrices is often limited because bioactive compounds are sequestered within complex lignocellulosic architectures, restricting their release and downstream activity. Fermentation-driven enzymatic biotransformation can overcome these structural barriers; however, the mechanisms by which fermentation-derived, non-viable functional ingredients (postbiotics) confer benefits remain incompletely defined. Here, we examined whether a postbiotic-rich, co-fermented plant matrix enhances host resilience under metabolic stress and whether such effects are accompanied by a remodeling of gut microbial functional capacity. A functional plant matrix was produced by solid-state co-fermentation using two Lactobacillus plantarum strains selected for complementary lignocellulolytic profiles. Untargeted metabolomics and deep shotgun metagenomic sequencing were integrated with a hydrocortisone-induced murine metabolic stress model to quantify substrate remodeling, host neuroendocrine/behavioral outcomes, and microbiome functional reprogramming. Co-fermentation markedly remodeled the phytochemical landscape, increasing extractable flavonoids and generating distinct metabolite clusters. In vivo, administration of the postbiotic-rich matrix partially normalized stress-responsive neuroendocrine markers (ACTH, TRH, and testosterone) and improved behavioral outcomes in open-field and forced swim assays. These systemic changes were paralleled by a coordinated shift in microbial functional potential, including the enrichment of carbohydrate-active enzyme (CAZyme) families involved in complex polysaccharide utilization (e.g., AA9, GH129, CE14) and attenuation of phosphotransferase system modules and cytochrome P450-related functions. Enzymatic synergy-driven biotransformation yields a postbiotic-rich functional matrix that is associated with a selective remodeling of gut microbiome metabolic potential under stress and concomitant improvement in host physiological resilience. This study underscores microbial functional remodeling as a critical mechanistic interface linking fermentation-modified substrates to host physiological recovery, providing a molecular framework for the development of targeted postbiotic interventions. Full article

The purpose of this study is to combine 3D printing and hot-pressing to improve polyvinylidene fluoride (PVDF) by making its surface smoother, enhancing crystallinity and electrical and mechanical performance. Before printing, PVDF filament was analyzed using rheology, differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA), and extrusion tests. Based on these results for printing, 250 °C was fixed as the optimized printing temperature. PVDF samples were printed using an Ultimaker S5 dual-nozzle 3D printer, with a size of 30 × 30 × 0.2 mm³. After printing, samples were hot-pressed at five different temperatures, 100, 125, 150, 175, and 200 °C, for 10 min each. Then, the hot-pressed samples were tested using morphology, Fourier transform infrared (FTIR), X-ray diffraction (XRD), DSC, tensile, and electrical properties. From the morphology, the sample thickness decreased from 0.25 to 0.24 mm, making the surface smoother, removing pores after hot-pressing. From FTIR and XRD results, all samples showed similar patterns, but the hot-pressed sample showed slightly stronger β-phase diffraction and peaks near 20° and 840, 1066, and 1275 cm⁻¹, indicating better crystal ordering. The DSC results showed a small increase in melting temperature and stable thermal behavior after hot-pressing, confirming improved thermal stability. The tensile property results confirmed that the hot-pressed samples, around 150 and 175, showed higher strength and better flexibility. The electrical I-V test showed stable and uniform conductivity, and the hot-pressed samples performed more consistently. Overall, hot-pressing improved the surface quality, crystallinity, mechanical, and electrical properties of 3D-printed PVDF, making it more reliable for advanced applications. Full article

Conventional buckling-restrained braces provide stable and efficient hysteretic energy dissipation but lack a recentering mechanism and adequate deformation capacity, which may result in significant residual deformations after strong earthquakes. Conventional self-centering braces reduce residual deformation but often provide limited energy dissipation under large seismic demands. To address these complementary limitations, a novel self-centering dual-stage yielding buckling-restrained braces is proposed. The device uses a two-stage core. A shape memory alloy first-stage core provides recentering. A low-yield-point steel second-stage core provides supplemental energy dissipation. An activation-displacement mechanism controls staged engagement of the two cores. Experimental tests validate the feasibility of the proposed configuration and confirm its stable hysteretic behavior and reliable recentering performance. A six-story concentrically braced steel frame is subsequently modeled in OpenSees, and nonlinear time-history analyses are performed to evaluate the seismic response of the system. Under an equal initial-stiffness design criterion, the seismic performance of frames equipped with the proposed brace is systematically compared with those incorporating a conventional self-centering brace and a conventional buckling-restrained brace. The numerical results indicate that the proposed system achieves enhanced control of interstory drift, mitigates weak-story behavior, and effectively reduces residual deformation under different seismic hazard levels while promoting a more uniform distribution of deformation along the structural height. Furthermore, a comprehensive parametric study is carried out to clarify the influence of key design parameters on displacement response and recentering performance, providing practical guidance for the seismic design and engineering application of the proposed brace. Full article