Search Results (2,838)

Multimedia recommenders can use behavioral records together with visual and textual item information, but unreliable interactions and sparse histories still make user preference modeling difficult. Most graph-based methods propagate messages over observed user–item edges as if all interactions were equally informative, so incidental or semantically inconsistent behaviors may distort the learned representations. The standard recommendation loss also provides limited context for modeling dependencies within a user’s historical sequence. We propose MGDSL, a MGDSL applies a multimodal-aware topology denoising module to calculate edge reliability weights for historical interactions from collaborative, textual, and visual evidence, and uses these weights for reliability-aware historical aggregation. In parallel, a masked self-supervised auxiliary task reconstructs masked items from sequence context, adding supervision for latent preference learning. Experiments on three benchmark datasets show that MGDSL consistently improves recommendation accuracy over competitive baselines, with particularly clear gains on the sparsest dataset. Full article

An ordinary state-based peridynamic (OSPD) approach combined with an interaction integral method is proposed to calculate dynamic stress intensity factors (DSIFs) and simulate crack propagation in two-dimensional cracked brittle solids. Numerical investigations are carried out for mode I and mixed-mode cracked plates under static, quasi-static, and dynamic loading conditions. A local damping scheme is incorporated into the peridynamic equations of motion to achieve convergence in static and quasi-static analyses. The influence of circular holes on DSIFs and crack propagation paths is systematically examined. Quantitative analyses of elastic deformation and quasi-static fracture behavior for mode I and mixed-mode cracks are verified through the uniaxial tension of a slab. The peak values of DSIFs exceed their static counterparts under dynamic loading. Complex dynamic fracture phenomena, including crack branching in both straight and inclined edge cracks, are successfully captured. The results obtained by the OSPD approach are validated through comparisons with theoretical benchmarks and finite element results, demonstrating high accuracy and effectiveness in calculating elastic deformation and stress intensity factors (SIFs), as well as accurately predicting crack propagation paths in quasi-static and dynamic fracture problems in brittle solids. Beyond the benchmark problems, the proposed OSPD approach is particularly well-suited for investigating more complex fracture systems. Full article

Frequent engineering changes in manufacturing require worker instructions to be updated quickly and reliably. In many production environments, however, update handling still depends on manual comparison procedures, delayed communication, or repeated traversal of large document collections, limiting responsiveness during ongoing production changes. This paper presents a hierarchical hash-based method for change detection in structured manufacturing documents as the computational core of a worker assistance system for near-real-time instruction updates in the context of in-line qualification. Heterogeneous instruction data are transformed into canonical hierarchical document structures, from which SHA-512 digests are generated at multiple structural levels. During repeated comparison operations, document-state evaluation is reduced to digest comparison, while structural differences can be localized through hierarchical refinement of affected substructures. The method is integrated into a system architecture that combines predecessor-linked version management with role-specific filtering for controlled dissemination of relevant instruction updates. The approach was implemented in an automotive assembly use case involving structured work instructions and evolving production documentation. The evaluation demonstrates that the proposed approach reduces repeated comparison effort relative to conventional field-wise traversal methods while maintaining the ability to localize structural changes through hierarchical refinement. The reported results focus on computational behavior and implementation feasibility in structured manufacturing environments rather than hardware-specific throughput benchmarks. Overall, the results indicate that hierarchical comparison of structured instruction states provides a practical basis for change-aware worker assistance and controlled propagation of instruction updates in evolving manufacturing environments. The evaluation focuses on repeated-comparison scenarios in structured manufacturing settings and does not address semantic interpretation of detected changes or large-scale distributed deployments. Full article

The extreme thermal environment during the underground coal gasification (UCG) process poses a severe threat to the stability of the gasification cavity and the integrity of the surrounding rock. This paper aims to reveal the thermo-mechanical response characteristics and damage evolution mechanism of sandstone under true triaxial unloading conditions following exposure to high temperatures. Sandstone specimens were thermally pre-treated at five temperature gradients (25 °C, 200 °C, 400 °C, 600 °C, and 800 °C) and subsequently subjected to true triaxial loading and unloading experiments. The effects of varying temperatures on the strength, deformation parameters, dilation angle evolution, and macroscopic failure modes of the sandstone were systematically analyzed. The results indicate a significant critical transition point in the mechanical behavior of the sandstone at 400 °C. Below this threshold, thermal-induced microcrack closure leads to an increase in peak strength (with the peak strength at 800 °C increasing by approximately 67% compared to room temperature). Conversely, above 400 °C, thermal damage to the mineral grains intensifies, causing the crack propagation pattern to transition from brittle shear to a complex tension-shear splitting mode, accompanied by severe dilatancy (with a generalized Poisson’s ratio exceeding 0.8). Based on these findings, this study proposes a stage-wise damage evolution model alongside a targeted zonal support strategy, recommending the application of high-prestressed support in high-temperature zones above 400 °C to suppress tensile failure. Ultimately, this research provides a crucial theoretical basis for evaluating the long-term stability of high-temperature underground engineering projects and ensuring operational safety. Full article

Grouting and sealing in gas drainage boreholes are two of the critical measures to ensure efficient coal seam gas extraction. However, traditional cement grouting often leads to debonding and cracking of the slurry–coal cemented body under external load, resulting in poor sealing performance. To suppress crack propagation and achieve borehole reinforcement and efficient sealing, this study compares the mechanical properties and crack evolution characteristics of slurry–coal cemented samples grouted with different modified materials. Five types of cement-based sealing materials, including ordinary Portland cement, were used for grouting coal rock in boreholes. By employing an acoustic emission signal acquisition system and a non-contact full-field strain measurement system, the tensile mechanical properties of coal before and after grouting were compared. The influence of material properties on the reinforcement capacity of borehole coal was analyzed, along with the failure process characteristics and final failure morphology of the slurry–coal cemented body under Brazilian splitting load. Finally, the effects of material toughness and bond strength on the brittleness index and failure mode of the slurry–coal cemented samples under Brazilian splitting conditions were discussed. The results show that the tensile strength improvement rates of the samples were 26.9%, 55.3%, 48.4%, 8.6%, and 45.6%, respectively. Distinct from previous studies focusing on fractured grouting or intact coal rock, this work for the first time systematically reveals the non-monotonic influence of the combination of material toughness and bond strength on the reinforcement effect of borehole coal samples and proposes an evaluation framework based on quantitative acoustic emission crack type analysis and the concept of effectiveness threshold. The varying degrees of tensile strength enhancement indicate differences in the reinforcement capabilities of grouting materials with different properties. The acoustic emission signals during the failure process of the slurry–coal cemented body exhibited typical stage-specific characteristics, though material properties altered the failure modes. By quantifying the intrinsic properties and crack characteristics of the slurry–coal cemented body using the brittleness index and grayscale histograms, this study provides a theoretical basis for guiding efficient sealing of gas drainage boreholes through an in-depth understanding of the mechanical behavior and crack evolution of borehole coal samples before and after grouting under Brazilian splitting conditions. Full article

This study investigates a 2D fractional order generalized thermoelastic problem in a homogeneous and isotropic thermoelastic hollow sphere. The sphere is exposed to a decaying heat source, and the governing equations are derived using a refined fractional-order Lord–Shulman (LS) model of generalized thermoelasticity. The Laplace transform technique is used to convert time-dependent PDEs into simpler ODEs in the Laplace domain. Its numerical inversion method is used to revert to the time domain. Numerical simulations are carried out to investigate the distributions of temperature, displacement, and stress fields within the hollow sphere. The obtained results reveal that both the fractional-order parameter and the variable thermal conductivity strongly affect the thermoelastic response, particularly the propagation characteristics of thermal waves, stress intensity, and relaxation behavior. In addition, the curvature of the hollow geometry plays an important role in modifying the radial and circumferential stress distributions and their attenuation throughout the medium. Full article

Achieving a favorable synergy of strength, ductility, and toughness is a critical challenge for expanding the engineering applications of titanium alloys. In this work, a medium-strength and high-toughness novel Ti-Al-Mo-V-Cr-Sn-Zr (named Ti62F) titanium alloy in the form of a Φ400 mm bar was adopted to systematically investigate the regulation behavior of double annealing on its microstructure and mechanical properties, and quantitative correlations between microstructural parameters and macroscopic properties were established. Increasing the cooling rate during the first annealing stage (air cooling, force air cooling and water quenching) significantly refined the secondary α (α_s) phase and reduced the volume fraction and size of the primary α (α_p) phase, leading to an increase in the ultimate tensile strength of the alloy from 1077 MPa to 1229 MPa. However, the impact-absorbed energy decreased from 51.5 J to 23.3 J. When the second annealing temperature was varied within the range of 625–675 °C, the ultimate tensile strength fluctuated slightly and the impact toughness increased moderately. Equiaxed α_p phase and relatively thick α_s can induce multiple crack deflections, prolong the crack propagation path and enhance energy absorption. Dislocations are mainly piled up at α/β phase boundaries, triggering void nucleation and growth, which dominate the ductility and toughness levels. Tensile twinning acts only as an auxiliary deformation mechanism and contributes limitedly to toughness. After heat treatment under the optimized schedule of 880 °C/2 h/AC + 650 °C/4 h/AC, the Ti62F alloy exhibits a superior strength–toughness balance compared with conventional medium-strength titanium alloys such as TA15, TC4, and TC4-DT. The findings can provide a heat treatment basis for microstructural regulation of large-size Ti62F bars and their engineering applications in aerospace structural components. Full article

In our research, we developed a Distributed Relaxation Spectrum Delay Differential Equation (DRSDDE) model to simulate viscoelastic responses exhibited by materials with multiple-scale relaxation mechanisms and finite delay times. Our model expanded upon traditional integer-order viscoelastic models to include a continuum relaxation process using a log-time-space Gaussian distribution representing a continuum of relaxation processes, including a direct representation of the effect of delayed feedback via an explicit time delay term. Consequently, the resultant model can be viewed as a generalized Maxwell-type formulation where the viscoelastic behavior exhibits distributed relaxation dynamics and has finite signal propagation characteristics. We then used experimental data obtained from three representative materials: PDMS Sylgard 184, bovine brain white matter, and polyurethane foam to calibrate the model. Calibration was achieved by estimating model parameters through the use of Gauss-Legendre quadrature combined with non-linear optimization of the relaxation spectrum. The results indicate that the coefficients of determination for each of the materials exceeded R² > 0.83. Therefore, the proposed DRSDDE model outperformed the classical Zener model when simulating materials that exhibit a wide relaxation spectrum. The parameter values estimated for each of the examined materials provided additional insight into their physical behaviors. Specifically, the characteristic relaxation times for the studied materials were determined based upon \(\tau\)_c = 10^µ ranging from about 63 s to 158 s. These results illustrate different dominant relaxation regimes for the investigated materials. Additionally, both characteristic equations and frequency domain analyses were utilized to study the stability and bifurcation properties of the DRSDDE model. A significant finding resulted from identifying a delay-insensitive stability regime for materials with \(\tilde{K} < 1\) (as illustrated by bovine brain white matter). For materials with \(\tilde{K} > 1\), the analysis revealed Hopf bifurcation results illustrating critical delay thresholds and frequencies for the onset of oscillations. Further, it was established that all calibrated delay values were significantly less than these threshold values. This indicates that all identified models functioned well below the oscillation thresholds at realistic delay times. Ultimately, the proposed DRSDDE model represents a physically intuitive, robust, and flexible method for modeling complex viscoelastic systems. Future research will involve investigating temperature-dependent effects, nonlinear bifurcations, and experimental validations of predicted oscillatory dynamics Full article

Dissolution-induced spalling is a major deterioration mechanism affecting the long-term stability of grottoes exposed to acidic environments. However, existing numerical methods have limited capability in capturing the coupled effects of hydrochemical dissolution, joint degradation, and fracture propagation. In this study, a hydrochemical damage-coupled Discontinuous Deformation Analysis (DDA) method is proposed. A mineral dissolution-based crack evolution model is first established, and a chemical residual strength factor D_c is introduced to quantify the degradation of fracture toughness, tensile strength, and shear strength. The factor is then incorporated into a nonlinear joint constitutive model to simulate the mechanical-chemical behavior. The proposed method is validated through a two-block contact model and a three-point bending test. Results show that the model accurately reproduces nonlinear contact behavior, including stiffness degradation, hysteresis, and peak strength reduction (24.6% after 90 days) under chemical erosion. Further application to a typical sandstone grotto reveals a progressive failure process characterized by crack initiation, propagation, coalescence, and eventual block detachment. The results demonstrate that hydrochemical dissolution significantly accelerates structural degradation of grotto rock masses, and that both the number of active cracks as well as the total crack length have significantly increased. The proposed method provides an effective tool for evaluating long-term stability and supports the preservation of grotto cultural heritage. Full article

Deep gas emissions in volcanic and tectonic environments are commonly interpreted as the surface expression of localized deep emitters. This representation is adequate for first-order description, but it is not physically complete. Deep degassing is more appropriately represented as a coupled source–storage–pathway system in which volatile generation, compressible accumulation, phase change, hydraulic communication, and permeability evolution are dynamically linked. Starting from phase-wise mass conservation in deformable porous–fractured media, reduced equations for gas migration, pore-pressure diffusion, and thermo-poro-mechanical coupling are derived, showing how the distinction between gas-mass transport and pressure propagation provides a unified framework for volcanic and tectonic degassing. Deep pressure gradients are shown to arise from the competition between volatile supply and pathway leakance, while episodic discharge can occur when permeability evolves under effective stress, sealing, and failure. A minimal analytical source–storage–pathway model is further derived, yielding explicit criteria for valve onset, source charging and discharge times, and the distinction between pressure-led and mass-led responses. The framework is then applied to the published Campi Flegrei carbon dioxide (${\mathrm{CO}}_2$) diffuse total output record, providing a real-data illustration of slow storage loading and rapid transient discharge. The analysis considers magmatic exsolution, hydrothermal mediation, metamorphic devolatilization, advective–diffusive near-surface filtering, and the inverse problem through which surface fluxes and gas compositions are used to infer deep source properties. The formulation links magmatic degassing, hydrothermal pressurization, tectonic fluid ascent, and fault-valve behavior within a common continuum-physics perspective and identifies the constitutive assumptions that most strongly control interpretation. Full article

This work evaluated the effect of enriched gas flood maturity and mobile water on transient foam behavior and oil recovery under high-pressure (2000 psi), moderate-temperature (38 °C) and salinity (20,000 ppm NaCl) conditions in high-permeability Bentheimer sandstone. A synthetic gas mixture containing relatively high contents of CO₂ (20%) and propane (26%) was used to simulate the enriched field gas. Screening of foaming surfactants including alpha olefin sulfonates and a betaine for good foamability and stability as well as low adsorption on the sandstone indicates that the alpha olefin sulfonate with a longer chain length was the best candidate for foaming the enriched gas in the presence of oil. Core flooding experiments conducted with this surfactant showed a strong impact of gas flood maturity and injection foam quality on both the transient foam behavior and oil displacement efficiency. Foam injection at residual oil saturation (about 14%) to a gas–brine flood exhibited robust foam propagation. The presence of mobile oil before foam injection due to the immaturity of the gas–brine flood (e.g., oil saturations above 50%) posed a detrimental effect on the rate of foam viscosity buildup. However, water injection during the pre-foam flood strongly supported foam generation even at relatively high oil saturations. A further evaluation of water contribution to enhancing foam propagation by adjusting foam quality showed that the water injection strategy before and during foam flooding should be optimized to improve both transient foam behavior and gas–oil contact for enhanced oil sweep efficiency. Full article

α-synuclein (α-syn) aggregation in dopaminergic neurons is a central event in Parkinson’s disease (PD) pathogenesis. Immunotherapeutic strategies targeting α-syn, including passive and active approaches, aim to inhibit aggregation, propagation, and toxicity of pathological species while promoting their clearance via immune mechanisms. This review summarizes α-syn directed immunotherapies evaluated in in silico, in vitro, and in vivo models, as well as early phase clinical trials, focusing on how epitope selection and antibody formats influence efficacy, safety, and target engagement. Data on monoclonal antibody, peptide, and protein-based vaccines, and structure-guided immunogens were analyzed, integrating behavioral, neuropathological, proteomic, and structural outcomes alongside biomarker development for α-syn species in cerebrospinal fluid and peripheral compartments. Clinical evidence indicates that several candidates induce sustained anti-α-syn antibody responses with acceptable safety profiles and signs of pharmacodynamic engagement, including reductions in free or oligomeric α-syn. However, consistent long-term clinical benefits remain unproven, highlighting the gap between preclinical success and disease modification in humans. Advances in structural biology and proteomics support rational epitope selection and improved immunogen design, reinforcing α-syn-targeted immunotherapy as a promising yet experimental strategy for PD, and highlighting the need for mechanistically oriented, biomarker-driven clinical trials initiated in well-characterized prodromal and early-stage cohorts. Full article

Borate-crosslinked hydroxypropyl guar (HPG) gels are widely used as water-based fracturing fluids in oilfield stimulation. During hydraulic fracturing, their effectiveness depends on the rapid formation of a low-permeability filter cake on fracture walls, which helps reduce fluid invasion, maintain fracture pressure, and support fracture propagation. In high- and ultra-high-permeability reservoirs, however, rapid matrix invasion may occur faster than effective filter-cake formation, causing severe pre-cake spurt loss or even uncontrolled leakoff. Conventional filter-paper tests tend to emphasize stabilized wall-building behavior and may therefore fail to represent the early-time spurt loss in porous reservoir media. In this study, the leakoff behavior of borate-crosslinked HPG fracturing fluids was investigated using a modified static fluid-loss apparatus. Experiments were conducted at differential pressures of 0.5–6.0 MPa through filter paper and artificial sandstone disks with permeabilities from 0.120 to more than 4.0 μm². The filter-paper tests showed typical wall-building behavior, with limited spurt loss and stable late-time leakoff. In contrast, the sandstone-disk tests revealed a transition from cake-controlled leakoff to early-time spurt-loss-dominated leakoff as permeability and differential pressure increased. When permeability exceeded approximately 1.55–2.42 μm², spurt loss (V_sp) became the main contributor to total leakoff, whereas the late-time wall-building coefficient (C_w) was much less sensitive to permeability. This indicates that permeability mainly controls the pre-cake invasion stage rather than the stabilized leakoff stage. Based on these results, an empirical spurt-loss model considering permeability and pressure differential was developed, and spurt-loss zoning maps were constructed for engineering evaluation. Limited ultra-high-permeability tests further showed that quartz particles promoted early bridging and reduced leakoff under moderate pressure differentials, but the particle-assisted barrier lost effectiveness under higher pressure differentials. These findings demonstrate that filter-paper-based criteria are insufficient for evaluating HPG gel performance in extreme-permeability formations and that a spurt-loss-based framework is needed for fluid-loss-control design and fracturing-fluid selection in high-permeability reservoirs. Full article

Hybrid transmission corridors combining overhead lines and underground cables introduce impedance discontinuities that significantly modify electromagnetic transient behavior. These discontinuities generate traveling-wave reflections, waveform distortions, and high-frequency components at relay measurement locations during the first microseconds following disturbance inception. This paper presents a waveform-level electromagnetic transient (EMT) analysis of overhead–cable transition effects using detailed EMTP-RV simulations including frequency-dependent line and cable models, tower representations, grounding systems, and instrument transformers within a differential protection measurement framework. The results show that overhead–cable transitions produce transient waveform modifications characterized by reflections, attenuation, dispersion, and temporary current imbalance mechanisms associated with traveling-wave propagation and cable capacitive effects. The analysis also demonstrates the transient evolution of instantaneous waveform-derived (EMT-derived) differential and restraining current quantities, defined as combinations of terminal current signals obtained directly from EMT waveforms. These quantities do not represent final phasor-domain operating values of practical numerical relays, but provide insight into the transient electromagnetic environment preceding conventional filtering and phasor estimation. The study contributes to a clearer physical interpretation of transient phenomena in hybrid transmission systems and supports EMT-based evaluation of signals relevant to differential protection applications. Full article

Using solid wastes to fabricate sustainable backfill materials for mining engineering is crucial for environmental sustainability worldwide. In this study, the use of coal gangue aggregates as a sustainable alternative to natural aggregates in geopolymer gel backfill materials was explored, which contributes to green mining development. Through uniaxial compression tests, the effects of fine gangue content, mass concentration, and the binder content of geopolymer backfill materials on the compressive behavior of coal gangue geopolymer gel backfill–rock combinations (CGBRC) were systematically evaluated. Digital Image Correlation (DIC) and acoustic emission (AE) techniques were employed to reveal the strain field evolution and damage progression of CGBRC. Results show that as the content of fine coal gangue increases, the compressive strength first increases and then decreases. Compared with the compressive strength at a 20% content, the compressive strength at a 40% content increased by 33.2%, while the elastic modulus increased by 11.2%. Meanwhile, with the increase in mass concentration and binder content, the compressive strength and elastic modulus of coal gangue geopolymer filling materials show an increasing trend, reaching peak values at 86% mass concentration and 32% binder content, respectively. The strain concentration zones mainly form near the backfill interface, with propagation paths governed by backfill strength. Damage evolution undergoes three stages including rapid accumulation during compaction, gradual development in the elastic-plastic stage, and abrupt acceleration at failure. The interfacial debonding behavior is primarily influenced by the strength difference between the backfill and surrounding rock. Specimen failure is dominated by brittle shear fracture, categorized into three modes based on crack paths relative to the backfill, which include penetrating backfill failure, axisymmetric interface failure, and centrally symmetric interface failure. These findings offer theoretical and technical support for coal gangue resource utilization and green mining practices, advancing sustainable solid waste management. Full article