Search Results (1,301)

This study addresses the early-age brittleness and performance limitations of sustainable cement soil. While prior works optimized the baseline compressive strength using recycled sand and nanoclay, the multi-scale synergistic effects of fibers and nanomaterials on the post-peak deformation remain underexplored. To address this gap, a composite modification system incorporating recycled sand, nanoclay, polypropylene fibers, and graphene derivatives was developed. The experimental program comprised standard specimen fabrication, early-age curing, and unconfined compressive strength (UCS) testing, supplemented by RBF neural network curve fitting and quantitative ArcGIS digital image processing of scanning electron microscopy (SEM) micrographs. The results demonstrate that optimizing the fiber parameters (0.6% content with 6 mm length) successfully increases the early UCS to 2263.2 kPa, which is further elevated to a peak of 2755.0 kPa upon co-incorporation with 0.05% small-sized graphene oxide. Correspondingly, a newly introduced ductility index quantitatively confirms that the single-fiber reinforcement yields an index of 1.93, which is further enhanced to 2.02 by the graphene composite system. Microstructure tracking and digital image extraction revealed that the SEM-derived surface porosity decreased significantly, exhibiting a clear inverse relationship with the macroscopic mechanical strength. These quantitative microstructural shifts confirm that graphene effectively filled micropores and reinforced the fiber–matrix interface, establishing a dense matrix network with enhanced interfacial bonding. This multi-scale approach offers a sustainable strategy for green geotechnical applications. Full article

Freeze-induced damage in concrete is governed by complex interactions between pore-scale phase transition and macroscopic mechanical response, while the underlying pore structure is typically difficult to observe directly. This study proposes an integrated framework for porosity inversion in concrete under freeze–heaving conditions, combining mechanical modeling, finite element simulation, and deep learning. A mechanics-based model is first developed to describe frost-heaving behavior in porous concrete, accounting for elastoplastic deformation of the matrix and partial volumetric expansion induced by pore water freezing. Based on this formulation, a parametric finite element model with randomly distributed pores is constructed to generate datasets linking pore characteristics to full-field deformation responses. Building upon these physics-consistent data, a deep learning framework is established to reconstruct pore distribution directly from three-component strain fields. The model employs a Vision Transformer backbone to capture global deformation patterns and incorporates a Kolmogorov–Arnold Network-based nonlinear mapping to enhance representation of the highly nonlinear inverse relationship. The results demonstrate that the proposed approach achieves accurate pore reconstruction and porosity prediction with stable convergence and satisfactory generalization performance across different porosity levels. The study provides a physically interpretable and computationally efficient pathway for linking deformation fields to internal pore structure, offering new potential for non-destructive characterization and durability assessment of concrete in cold-region environments. Full article

Polyvinylidene fluoride (PVDF)/clay nanocomposite membranes with different nanoclay loadings (0–5 wt%) were prepared via the non-solvent induced phase inversion method. Effects of organo-montmorillonite (OMMT) content on the morphology and performance were systematically investigated. Results showed that OMMT was uniformly exfoliated and dispersed in the PVDF matrix, while the nanocomposite membranes consistently maintained the β-crystalline phase of PVDF. The incorporation of nano-clay significantly enhanced membrane hydrophilicity, porosity, pure water flux, and protein rejection performance: when clay content increased to 5 wt%, the pure water flux improved from 89.8 L·m⁻²·h⁻¹ to 216.3 L·m⁻²·h⁻¹, with rejection rates of 98.6% for bovine serum albumin (BSA) and 95.1% for pepsin. Mechanical tests showed that 3 wt% was the optimal clay loading, at which the storage modulus of the membrane increased by 59.8% compared to neat PVDF membranes. Antifouling experiments revealed that the nanocomposite membranes exhibited significantly lower irreversible fouling resistance, substantially improved hydraulic cleaning flux recovery rates, and markedly enhanced antifouling properties. Furthermore, long-term stability, economic analysis, and environmental safety assessments confirmed the practical application potential of these nanocomposite membranes in water treatment. These findings provide theoretical support and technical references for the preparation and application of high-performance PVDF ultrafiltration membranes. Full article

Phase-inversion in situ implants (PIISIs) represent a versatile polymer platform in which the rational choice of matrix former and solvent system directly governs the macroscopic properties of the resulting depot. This study applied a Quality by Design (QbD) approach to rationalize a bleached shellac–based PIISI, with particular focus on the physicochemical interactions between the polymer and the injection vehicle. Bleached shellac—a natural, low-cost, biodegradable oligomeric resin bearing –COOH, –OH, and ester functional groups—was selected as the matrix former and screened in seven neat solvents and five 1:1 binary combinations at 25% (m/m). Twelve formulations were evaluated against a predefined set of critical quality attributes, including injectability, phase-inversion kinetics, solvent diffusion volume, and implant structure (n = 5 per formulation; mean ± standard deviation (SD); one-way analysis of variance (ANOVA) with Tukey’s post hoc test, p < 0.05). Three lead solvent systems—propylene glycol/N-methylpyrrolidone (PG+NMP), PG/dimethyl sulfoxide (PG+DMSO), and DMSO/benzyl alcohol (DMSO+BA)—were identified as those providing an optimal balance between hydrogen-bond donor/acceptor solvation and controlled solvent extraction. In the second stage, shellac concentration (20–35%) was optimized, with 30% shellac in PG+NMP yielding the fastest phase inversion (~50 s), a structurally uniform matrix, and the lowest swelling (22%). A working mechanistic framework consistent with all observed critical quality attribute (CQA) trends in which solvent hydrogen-bond donor/acceptor balance and water miscibility govern implant architecture is proposed, and it is intended as a hypothesis-generating basis for the rational design of PIISI formulations; direct validation by spectroscopic, thermal-analytical, and biological methods is identified as the next step. The developed formulations are presented as a preliminary physicochemical platform; biological validation (in vitro cytocompatibility and inflammatory response assessment) is required before the system can be considered a validated formulation for dental drug delivery. Full article

The solution theory of Sylvester-type equations finds wide applications in control theory, robotics, and image processing. This paper systematically surveys, classifies and summarizes the existing research results of three classes of Sylvester-type equations: matrix equations, tensor equations, and operator equations. It extracts nine mainstream research methods and clarifies the internal correlations among these methods, as well as their applicable equation types. Combined with four prior review articles focusing on special cases of Sylvester-type equations, this work establishes a comprehensive framework for solving such equations. It not only provides a systematic theoretical foundation and a clear research thread for subsequent researchers but also offers valuable methodological insights for further investigations in related fields. Full article

Cooperative deployment of mobile agents under geometric and line-of-sight constraints gives rise to high-dimensional constrained optimization problems whose underlying physical configuration often exhibits exploitable structure. This paper develops a symmetry-driven inverse design framework that leverages two structural features of the engagement geometry—the ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ mirror symmetries of the extended target silhouette and a closed-form forward–inverse correspondence between line-of-sight-aligned burst locations and physical agent parameters—to construct low-dimensional seeds for subsequent physical parameter optimization. The framework is developed and validated on a representative naval defense instance in which a fleet of unmanned aerial vehicles (UAVs) releases spherical obscuration payloads to interrupt the line of sight between incoming mobile threats and a cylindrical extended target. Instead of searching only over the four-dimensional UAV parameter space (heading angle, speed, drop time, fuse delay), the method first specifies a desired burst location in a two-dimensional inverse space and analytically back-calculates feasible agent parameters, which are then refined by multi-start Nelder–Mead optimization in the physical parameter space. A conservative three-dimensional cylindrical line-of-sight obscuration model is developed by constructing four extreme tangent sightlines from the missile to the cylindrical target and verifying whether the spherical smoke cloud simultaneously blocks all of them. A hierarchical multi-agent task allocation framework combines a performance matrix, assignment enumeration, and joint multi-start refinement. Numerical experiments on five progressively complex sub-problems demonstrate obscuration durations of $1.362 \mathrm{s}$ (single fixed shot), $4.580 \mathrm{s}$ (optimized shot), $7.324 \mathrm{s}$ (three-shot relay), $11.140 \mathrm{s}$ (three-UAV cooperation), and $20.652 \mathrm{s}$ (full five-UAV three-missile assignment). Additional high-dimensional benchmarks, sensitivity tests, and error analyses clarify the reproducibility and limitations of the approach. Full article

In shale reservoirs, where stress heterogeneity and fracture systems commonly coexist, elastic anisotropy is jointly controlled by in situ stress and fractures, resulting in pronounced azimuthal dependence in wide-azimuth AVO/AVAZ responses. This behavior directly affects fracture characterization and hydraulic fracturing design. However, existing studies commonly attribute anisotropy to either fractures or uniaxial stress perturbations in isolation, and a systematic equivalent-medium formulation that unifies stress-driven stiffness evolution with fracture-weakness effects remains insufficient. To address this gap, we derive an acoustoelastic expression under the weak-stress perturbation assumption, combining background stiffness with third-order stress effects. By incorporating linear-slip fracture weakness, we construct a coupled stress–fracture equivalent stiffness matrix. Using Christoffel eigenanalysis and a welded-interface operator, we then compute anisotropic parameters and AVAZ responses under different stress paths. Numerical simulations show that the principal stress difference dominates both the splitting of reflection curves and azimuthal fluctuations, with an approximately linear sensitivity within the weak-stress regime. Unlike conventional descriptions of fracture-induced anisotropy, in which fracture parameters are commonly prescribed, the proposed framework constructs a physically traceable modeling chain from triaxial stress perturbations to stress-dependent fracture weakness, equivalent orthorhombic stiffness, Christoffel-equation-based wave propagation, and AVAZ responses. This provides a forward-modeling foundation for interpreting coupled stress–fracture anisotropy and for designing future inversion constraints under weak-perturbation conditions. Full article

In this study, we propose a matrix-based transformation framework constructed from special integer sequences, including Fibonacci, Lucas, Pell, and Jacobsthal numbers. The approach is based on block-wise $2\times 2$ matrix transformations that preserve key structural invariants, particularly the determinant, ensuring explicit invertibility of the scheme. By combining multiple recurrence-based matrices within a unified framework, the method provides flexible forward and inverse transformations without increasing matrix dimensions or introducing additional redundancy. The determinant-preserving property enables intrinsic consistency checking and supports an analytic error-detection and correction mechanism at the block level. Several illustrative examples are presented to demonstrate the applicability of the proposed scheme and its computational characteristics. The framework is purely algebraic and can be extended to other matrix families generated by linear recurrence relations, making it suitable for a wide range of applications in applied and computational mathematics. Full article

Accurate monitoring of mining-induced three-dimensional surface deformation is critical for safety and environmental protection. Conventional InSAR often loses coherence in high-deformation areas and provides only one-dimensional measurements, while the Probability Integral Model (PIM) suffers from low accuracy at subsidence edges, caused by premature numerical convergence of its error-function-based mathematical formulation—the model prediction rapidly drops to zero and fails to capture subtle real-world deformations in marginal zones. This study developed a fusion method integrating multi-source InSAR (Sentinel-1A and SAOCOM), PIM, and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). Applied in the Yinying Mining Area, Shanxi Province, the approach combined ascending and descending SAR data processed via SBAS-InSAR, used CMA-ES to optimize PIM parameter inversion, and employed a zonal fusion strategy to reconstruct complete deformation fields. The method demonstrated substantial improvement in monitoring accuracy, with mean absolute errors in the vertical, north–south, and east–west directions reduced by more than 86% compared with the standalone PIM model in edge zones. The fusion approach effectively captured both large-magnitude center deformations and subtle edge displacements. Multi-source data fusion with intelligent optimization algorithms significantly enhances the accuracy of 3D deformation monitoring in mining areas, providing reliable technical support for safety management and environmental protection. Full article

High-density (HD) quasi-cyclic low-density parity-check (QC-LDPC) codes are widely adopted in high-speed, high-reliability optical communication systems. However, the high density of the quasi-cyclic parity-check matrix prevents the direct derivation of a corresponding quasi-cyclic generator matrix, leading to computationally prohibitive encoding complexity. To address this limitation, based on the established polynomial-ring representation of QC-LDPC codes, this paper develops a structure-preserving polynomial-domain transformation for the high-density 50G-PON QC-LDPC parity-check matrix. The proposed method transforms the dense quasi-cyclic parity-check matrix into a compact systematic encoding form over $R={\mathbb{F}}_2\left[x\right]/(x^{256}-1)$. As a result, parity generation is reduced to the inversion of a small $3\times 3$ polynomial submatrix and a sequence of cyclic-shift-and-XOR operations. Based on this construction, an optimized HD-QC-LDPC encoding algorithm and its corresponding FPGA architecture are developed. The resulting hardware encoder achieves a throughput of 58.9 Gbps at a 200 MHz clock frequency on a Xilinx Kintex-7 FPGA, satisfying the throughput and latency requirements of 50G-PON systems. Full article

This work extends the analytical operation of the Riemann–RHPHilbert approach (RHA) for fractional-order nonlinear integrable systems under the solvable meaning of inverse scattering transform (IST) to variable-coefficient fractional-order nonlinear models. Firstly, based on the matrix spectral problem proposed by Ablowitz, Kaup, Newell, and Segur, this article derives an integer-order integrable system, which is abbreviated as the AKNS hierarchy. Secondly, by taking specific values of the operator in the derived AKNS hierarchy, a variable-coefficient fractional higher-order NLS hierarchy (vfhNLSH) is obtained, and its anomalous dispersion relation (ADR) is derived via formal solution. Significantly, the reductions of the vfhNLSH include three variable-coefficient fractional-order integrable models: the Hirota equation (vfHE), the Lakshmanan–Porsezian–Daniel equation (vfLPDE), and the fifth-order NLS equation (vffNLSE). Finally, we conduct a detailed study on the representative vfHE as an example rather than a special case and construct its explicit N-fold analytical solution based on the extension of the RHA. At the same time, numerical visualization simulations are conducted to demonstrate the waveform structure characteristics of the solutions under $N=1$ and $N=2$ conditions, including solitons, breathers, and their coupled nonlinear waves. The same process is fully applicable to the other two reduced models, with only some differences in the related results and the dynamic behavior of the solutions. It is shown that the temporal part of the Lax pair associated with the vfHE cannot yet be explicitly determined. Therefore, the fractional-order extension of the RHA presented in this article constitutes a formal or RHA-inspired construction, rather than a fully rigorous fractional-order RHA extension. Full article

High-performance polyethersulfone (PES) ultrafiltration membranes integrating antibacterial activity and antifouling performance were fabricated via the in situ construction of bimetallic polyphenol networks (BMPNs) throughout the membrane architecture. Tannic acid (TA) functioned as a multifunctional molecular bridge, functionalizing silver metal–organic frameworks (Ag-MOFs) to yield hydrophilic T-Ag-MOFs and chelating Fe³⁺ ions from the coagulation bath to form a polyphenol network during phase inversion. T-Ag-MOF incorporation generated asymmetric morphologies featuring highly porous surfaces and sponge-like cross-sections, improving pure water permeability, mechanical integrity, and bovine serum albumin (BSA) rejection. TA-mediated functionalization increased hydrophilicity, imparted a negative surface charge, suppressed nonspecific protein adhesion, and enhanced flux recovery with low irreversible fouling. At an optimal loading of 0.4 wt%, the resultant T-Ag-MOF/Fe³⁺/PES composite membrane achieved a pure water permeability of 593.4 L m⁻² h⁻¹ bar⁻¹—1.77-fold higher than that of the pristine PES control—while sustaining a BSA rejection of 96.5%. Notably, interfacial compatibility between the T-Ag-MOFs and PES matrix was enhanced, facilitating strong, covalent-like filler–matrix adhesion. Moreover, the composite membrane delivered synergistic multifunctionality, including exceptional long-term aqueous stability, precisely tuned Ag⁺ release kinetics, and potent antibacterial activity, as evidenced by negligible uncontrolled ion leaching and a lack of structural degradation under prolonged hydration. Full article

In this paper, we present explicit representations for Drazin inverses of the sum $P+Q$ under the conditions $P^{2}Q=0$, $Q^{2}PQ=0$, and $Q{\left(PQ\right)}^2=0$. Then, we apply our results to derive a series of representations for the Drazin inverses of a $2\times 2$ complex partitioned matrix $\left[\begin{array}{cc}A& B\\ C& D\end{array}\right]$, where A and D are square complex matrices. Numerical examples are provided to show that the assumptions used here are genuinely weaker than those in a number of earlier results. Full article

Efficient protein aggregate removal remains a major challenge in downstream bioprocessing because high aggregate clearance must be achieved without compromising monomer yield. Mixed-mode chromatography (MMC) has emerged as a promising approach, offering enhanced selectivity through combined ionic and hydrophobic interactions and salt-tolerant behavior. However, the relative roles of matrix pore accessibility and ligand density remain insufficiently understood. In this study, MMC adsorbents based on 4% and 6% agarose matrices were functionalized with a BMEA ligand. Inverse size-exclusion chromatography revealed that functionalization caused matrix syneresis, increasing dry matter content to 23% and enhancing mechanical rigidity. MMC-Ag4, with a larger mean pore radius (19.1 nm), exhibited a selectivity factor of 2 toward aggregates in static binding experiments, whereas the denser MMC-Ag6 (15.7 nm) showed no selectivity. In column studies using a feed containing 10% aggregates, MMC-Ag4 outperformed the commercial benchmark Capto Adhere, achieving monomer yields of 80–90% at 97–98% purity with salt tolerance up to 300 mM NaCl. These findings indicate that while MMC-Ag6 is limited by pore blockage, the optimized pore accessibility of MMC-Ag4 enables effective aggregate recognition. In conclusion, multimodal adsorbent design must balance ligand density with matrix porosity to ensure high resolution and yield in aggregate removal. Full article

Polymeric membranes are widely investigated for CO₂ separation; however, their performance is often limited by the permeability–selectivity trade-off. Incorporating metal–organic frameworks (MOFs) and designing composite membrane architectures are promising strategies to overcome these limitations. This study aims to evaluate the effect of incorporating MOF-74 (Cu and Ni variants) into a polydimethylsiloxane (PDMS) selective layer supported on a polysulfone (PSF) membrane for enhanced CO₂/N₂ separation performance. Dual-layer PDMS/PSF composite membranes were fabricated via phase inversion for the PSF support, followed by solution casting of the PDMS/MOF layer. The developed membrane architecture introduces a synergistic design that combines the mechanical robustness of PSF with the selective transport capability of PDMS and the strong CO₂ affinity of MOF-74, offering an effective strategy for improving gas separation efficiency. Gas permeation performance was assessed using single-gas CO₂ and N₂ measurements at feed pressures of 2–5 bar. The incorporation of MOF-74 improved CO₂ transport properties, with the 1 wt.% Cu-MOF-74 composite membrane achieving a CO₂ permeance of 912.5 GPU and a CO₂/N₂ ideal selectivity of 94.75. The dual-layer configuration significantly enhanced permeance compared with unsupported mixed-matrix membranes while maintaining selectivity. Additionally, the composite membranes exhibited improved mechanical strength due to the PSF support layer. The findings demonstrate that dual-layer PDMS/PSF composite membranes incorporating MOF-74 provide a promising proof-of-concept approach for improving CO₂ separation performance. Further studies involving mixed-gas testing and long-term stability are required to assess their practical applicability. Full article