Search Results (396)

Accurate identification of land subsidence types is essential for effective urban risk management, yet remains challenging due to the superposition of deformation signals at different spatial scales and the complexity of urban environments. In this study, land subsidence types in Fuzhou were identified through an integrated framework combining multi-scale deformation analysis and ensemble learning. Ground deformation time-series measurements were derived from 66 Sentinel-1A synthetic aperture radar (SAR) observations acquired between January 2018 and June 2023 using the time-series interferometric synthetic aperture radar (TS-InSAR). Deformation values in decorrelated areas were subsequently reconstructed using regression models driven by multi-source geological, hydrological, land-use, and urban features, resulting in a spatially continuous deformation field. A Fast Fourier Transform (FFT)-based Butterworth filtering approach was then applied to separate regional-scale and local-scale subsidence signals. Based on the extracted local deformation patterns and discriminative auxiliary features, land subsidence was classified into five categories: farmland-related subsidence, linear infrastructure-related subsidence, low-lying stratum-related subsidence, land-use transition-related subsidence, and older building area-related subsidence. Three ensemble learning models, XGBoost, CatBoost, and LightGBM, were implemented for subsidence type classification. All models achieved satisfactory performance, among which LightGBM exhibited the best overall performance. The classification results reveal pronounced differences in spatial distribution and deformation intensity among subsidence types. Farmland-related subsidence occupies the largest proportion of the affected area but is characterized by relatively moderate deformation rates, whereas older building area-related subsidence, despite its limited spatial extent, exhibits the highest deformation intensity. This study demonstrates the potential of ensemble learning for land subsidence type classification. Full article

Asphalt serves as the core binder for heavy-load high-modulus pavements, and its viscoelasticity across a wide temperature range directly governs pavement-rutting resistance, low-temperature crack resistance and service life. Virgin asphalt contains abundant light fractions and exhibits insufficient stiffness at high temperatures. Modification with single styrene–butadiene–styrene block copolymer (SBS) fails to meet the anti-deformation requirements under heavy loads, while separate incorporation of nano-silica (nano-SiO₂) aggravates low-temperature brittleness. Existing studies lack comprehensive investigations into the rheological evolution laws and synergistic microscopic mechanisms of asphalt modified by combined SBS and nano-SiO₂. In this paper, virgin asphalt was adopted as raw material to prepare composite modified asphalt with gradient dosages. Integrated macroscopic performance tests and multi-scale microscopic characterizations were conducted for systematic analysis. High-temperature, low-temperature and fatigue performances were evaluated via conventional physical property tests, temperature sweep tests, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS) and bending beam rheometer (BBR) tests. Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and thin-layer chromatography–flame ionization detection (TLC-FID) were utilized to analyze variations in functional groups, molecular weight and four fractions, to elaborate the two-phase synergistic modification mechanism. The results demonstrate that the combined incorporation of SBS and nano-SiO₂ synchronously optimizes the comprehensive performances of asphalt. Compared with single-SBS-modified asphalt, the sample with optimal dosages achieves elevated high-temperature modulus and rutting factor, reduced permanent deformation, improved low-temperature stress relaxation capacity and remarkably decelerated fatigue damage accumulation rate. Microscopic characterizations verify that only physical interactions occur during modification without generating new substances. The nano-filler facilitates the aggregation of small molecules and increases the proportion of macromolecules; meanwhile, it physically adsorbs light fractions and induces apparent redistribution of asphalt components, raising the relative proportion of resins and asphaltenes in the organic asphalt phase, realizing moderate heavy-fraction enrichment of the asphalt system. This study clarifies the internal correlation between molecular fraction evolution characteristics and macroscopic rheological performances of asphalt co-modified by nano-SiO₂ and SBS, which can provide theoretical references for formula design and engineering application of modified asphalt materials. Full article

Active radar jamming recognition is an important technology in modern electronic warfare (EW). With the increasingly widespread application of Digital Radio Frequency Memory (DRFM) technology, the types of jamming have become more diverse. Meanwhile, in most non-cooperative confrontation scenarios, it is difficult to obtain large-scale labeled jamming samples. The commonly used methods for radar jamming signal recognition have some limitations. One is that they require a large number of jamming samples; the other is that their recognition performance degrades severely in few-shot scenarios. To address these limitations, an Adaptive Confidence Dual-Branch Fusion Network (ACDF-Net) is proposed for few-shot jamming recognition. The Short-Time Fourier Transform (STFT) is firstly used to obtain four-channel time–frequency features of the jamming signal, which fully retains the real part, imaginary part, amplitude, and phase information of jamming. Secondly, a dual-branch complementary representation learning network is well designed to extract jamming modulation characteristics and energy-phase characteristics. Finally, an adaptive confidence fusion method controlled by learnable parameters and a multi-task supervised learning paradigm are introduced, which improve recognition accuracy and make the network more robust. A mixed dataset containing 15 types of radar active jamming (including 8 single jamming types, 3 composite jamming types, and 4 real measured jamming types) is established to verify the proposed method. Multi-dimensional validation experiments are conducted, including few-shot performance comparison under different training set proportions (3~11%), per-class recognition performance analysis, measured data generalization validation, and ablation studies of core modules. In few-shot scenarios, the OA of ACDF-Net reaches 92.81% under 3% training data proportion, which is better than the comparison algorithms. More comparative experiments show that the proposed method is better than the comparison methods. The proposed method provides an effective solution for radar active jamming recognition in few-shot and complex electromagnetic environments, which exhibits high feasibility for practical engineering applications. Full article

Motor fault identification is often constrained by scarce labeled samples and the limited representation capability of a single time–frequency transform. Conventional CNN–Softmax models may also produce unstable decision boundaries under small-sample conditions. To address these issues, this paper proposes a motor fault identification method based on the fusion of fixed-resolution and multiscale time–frequency features. Each vibration segment is transformed into short-time Fourier transform (STFT) and synchrosqueezed wavelet transform (SWT) maps. Two parallel convolutional branches extract complementary features, which are fused by element-wise addition and classified using a radial basis function support vector machine. Experiments on the HUST motor multimodal fault dataset show that the proposed method achieves 100% accuracy under the conventional 70%/30% train–test split. When the training proportion is reduced to 20%, 15%, 10%, and 5%, the corresponding accuracies remain at 99.46%, 99.10%, 98.78%, and 96.77%, respectively. Across operating speeds of 5, 10, 20, and 30 Hz, the average accuracies reach 98.75% and 94.61% under the 20% and 5% training conditions. The model also maintains 100% accuracy at signal-to-noise ratios of 15 dB and above. These results demonstrate that complementary time–frequency feature fusion combined with maximum-margin classification improves identification accuracy and decision-boundary stability under limited training data. Full article

This paper develops a Fourier framework internal to proportional arithmetic on the positive real line. We construct the corresponding complex scalar field, differential and integral operators, oscillatory kernel, Fourier transform, and proportional function spaces. A correspondence theorem proves that the representative of the proportional transform is the classical Fourier transform under the logarithmic identification. Consequently, inversion, Plancherel, convolution, Schwartz invariance, and Sobolev characterizations follow by transport. We establish the exact relation with Fourier analysis on the multiplicative group and with the Mellin transform on the imaginary axis. Model resolvent and heat equations illustrate the operational calculus, while a scale-localized profile shows how spectral modulus and phase encode log-scale width and preferred scale. The construction is therefore a systematic proportional-arithmetic realization of classical harmonic analysis, rather than an analytically independent Fourier theory. Full article

Severe electrochemical corrosion and leaching degradation of underground structures are induced by coupled stray current and groundwater in rail transit systems like subways. The microstructural evolution of fly ash geopolymer (FAG) during accelerated leaching was systematically investigated by simulating a coupled direct current (DC) stray current and soft water environment. Pore solution alkalinity and electrolytic cell OH⁻ concentration were utilized as evaluation indicators, combined with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). Results indicate that substantial OH⁻ leaching occurs under the coupled stray-current and soft-water exposure, leading to reduced pore-solution alkalinity and changes consistent with the degradation of the N–A–S–H binding network. Consequently, porosity, most probable pore diameter, and the quantity of harmful pores are increased. However, no obvious changes in the major diffraction peaks associated with quartz and mullite were detected within the resolution of the qualitative XRD analysis. Furthermore, a linearly decreasing trend over time is observed for the coupled leaching rate. Mix proportion analysis demonstrates that FAG leaching resistance is improved by reducing the water-to-binder ratio; specifically, superior gel phase content and pore structure are maintained at a ratio of 0.30. Additionally, cumulative OH⁻ leaching is effectively reduced by decreasing the sodium silicate modulus, with optimal resistance exhibited between 1.0 and 1.2. Concurrently, pore solution alkalinity before and after leaching is significantly elevated by increasing the alkali dosage. This exerts a pronounced inhibitory effect on OH⁻ leaching, thereby substantially enhancing the overall leaching resistance. Full article

Microencapsulation has become an indispensable technique across various industries that require the controlled release and stability of bioactive agents. In this study, the encapsulation of cinnamon essential oil (CEO), known for its antibacterial and anti-inflammatory properties, was study to enable controlled release when applied to textile substrates. This procedure involves defining and examining several steps to establish a stable, scalable complex coacervation methodology. To form a stable microcapsule matrix, CEO was emulsified using a combination of surfactants (Span 80, Tween 20, and Sodium Dodecyl Sulfate). After forming micelles containing CEO, two biopolymers (chitosan and gum Arabic) were used at various proportions to form a microcapsule shell via a layer-by-layer approach. Advanced characterization techniques, such as spectrophotometry and laser scattering, were used to evaluate microcapsule stability, size, and release kinetics, as well as to assess potential antibacterial activity. The presence of oil-containing microcapsules was confirmed using fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The results demonstrate that Span 80 concentrations of 0.4 and 0.7 g/L provided the most stable encapsulation environment and enabled a controlled CEO release profile after being applied to cotton substrates. In addition, the influence of the fabric’s chemical characteristics was clearly illustrated in the drug delivery experiments. However, antibacterial efficacy was limited due to the low CEO concentration within the microcapsules, indicating the need for further optimization. These findings provide valuable insights into the broader application of essential oil encapsulation, particularly within the pharmaceutical, textile, and cosmetic sectors. Full article

Fish processing by-products represent a valuable and sustainable source of collagen for biomedical and functional applications. In the present study, collagen was extracted from the scales of red mullet (Mullus barbatus), gilthead sea bream (Sparus aurata), and European sea bass (Dicentrarchus labrax) using a green extraction approach based on a natural deep eutectic solvent (NADES) system composed of citric acid, xylitol, and water. The extracted collagens were comprehensively characterized by SDS-PAGE, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses. The results confirmed the presence of Type I collagen and demonstrated that the characteristic triple-helical structure and molecular organization were preserved throughout the extraction process. To preliminarily evaluate their potential as matrices for incorporating bioactive compounds, collagen matrices were combined with Zingiber officinale (ginger) extract at different ratios. The resulting combinations were evaluated for antioxidant, antimicrobial, and cytocompatibility properties. Antioxidant activity increased significantly with increasing ginger concentration, with the highest radical scavenging activity observed in combinations containing the greatest proportion of ginger extract. Similarly, antimicrobial activity against Escherichia coli and Staphylococcus aureus was enhanced by ginger incorporation, with stronger inhibition observed against the Gram-positive bacterium. Cytocompatibility studies performed on human dermal fibroblast (HDFa) cells revealed that selected collagen–ginger combinations maintained high cell viability and did not induce substantial membrane damage, nuclear abnormalities, apoptosis, or necrosis at appropriate concentrations. Overall, the findings demonstrate that fish scale-derived collagen obtained through a sustainable NADES-based extraction process possesses favorable structural and biological properties and may serve as a potential carrier matrix for plant-derived bioactive compounds. These findings provide preliminary evidence supporting the future development of environmentally friendly functional biomaterials with prospective applications in pharmaceutical, biomedical, and tissue engineering fields. Full article

Silica gel polymer material with imprinted phosphate cavities was successfully obtained using one-pot sol–gel reaction. Differences in the textural properties concerning the reduction in specific area and pore size between functionalized and pristine silica gel demonstrated the presence of the phosphate moieties in the cavities. The chemical and structural characterization of the functionalized material before and after copper adsorption was performed by Fourier-transform infrared spectroscopy (FTIR) and solid-state ²⁹Si and ³¹P nuclear magnetic resonance (NMR) spectroscopy. All these measures proposed a phosphate non-covalently bound in the cavities of the silica gel and stabilized by silanol groups on the surface of the matrix. The phosphate–copper complex is removed after the metal desorption process, and the free cavities in the silica matrix can be replenished with phosphoric acid without affecting its adsorption capacity. The entire process of phosphate incorporation, copper adsorption, and metal-ligand desorption was repeated in three cycles, showing a similar metal adsorption capacity. Energy-dispersive X-ray spectroscopy (SEM-EDX) experiments were performed to monitor the presence and proportion of phosphorus and copper at each step of the phosphate loading and copper adsorption processes. These results demonstrate the feasibility of synthesizing a rechargeable polymer material with functional molded cavities with phosphate groups capable of adsorbing copper ions. Finally, this investigation represents the first approach to new materials with a rechargeable ligand system for the adsorption of heavy metals. Full article

Melanin is a natural biopolymer with broad biological activities, yet research on melanin from the medicinal fungus Ophiocordyceps sinensis remains insufficient. In this study, two melanin fractions, TZ-a and TZ-b, were isolated from its fermentation products and characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA) and Ultraviolet–Visible spectra (UV-Vis). Their protective effects against UVB-induced damage in keratinocytes and heavy metal (Cd²⁺, Pb²⁺, As³⁺, Hg²⁺) cytotoxicity were evaluated. Both fractions exhibited characteristic melanin peaks but showed structural differences. TZ-a displayed lamellar or needle-like crystals, whereas TZ-b formed block-like aggregates. Both demonstrated good thermal stability. UV-Vis spectra confirmed their typical melanin identity. At 200 μg/mL, TZ-a and TZ-b increased cell viability from ~50% (model) to 80.59% and 82.48%, respectively. Additionally, they elevated the proportion of viable cells within the apoptotic population from 59.11% to 86.08% and 84.79%. Both fractions concentration-dependently alleviated heavy metal-induced cytotoxicity, reduced malondialdehyde levels, and restored glutathione pools. In conclusion, the melanin fractions TZ-a and TZ-b from O. sinensis exhibited photoprotective effects and alleviated heavy metal toxicity. Full article

Grape cultivation and processing generate large amounts of pruned vine branches and grape pomace, which can be converted into biochar as an effective recycling strategy. This study aimed to investigate the effects of pyrolysis temperature (300–600 °C) and residence time (0.5–4 h) on biochar physicochemical properties and to evaluate the short-term impacts of biochar–manure co-application on vineyard soil physical quality. A total of 13 biochar variants were produced from vine branches (9 treatments, L₉(3²) orthogonal design) and grape pomace (4 treatments, L₄(2²) orthogonal design) under oxygen-limited pyrolysis. Biochar properties were characterized using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Based on comprehensive evaluation, branch-derived biochar pyrolyzed at 300 °C for 4 h (BC4-300; specific surface area: 24.07 m²·g⁻¹) and pomace-derived biochar pyrolyzed at 300 °C for 1 h (BP1-300; pH: 8.2–9.1) were selected as optimal soil amendments. A field experiment was then conducted using a randomized complete block design with ten treatment combinations (five for each biochar type), in which biochar was applied at 10 or 30 t·ha⁻¹ and co-applied with cattle manure at 10 or 30 t·ha⁻¹. After one growing season, BC4-300 significantly enhanced topsoil (0–20 cm) aggregate stability, increasing the mean weight diameter (MWD) by up to 27.8% compared with the control. In contrast, BP1-300 significantly improved subsoil (20–40 cm) aggregate stability, increasing the proportion of water-stable aggregates > 0.25 mm (R_0.25) by 15.6%. Moderate application rates (10 t·ha⁻¹ biochar + 10 t·ha⁻¹ manure) reduced subsoil bulk density by 6.3%. These findings demonstrate that optimizing pyrolysis parameters enables feedstock-specific biochar production and provide practical guidance for short-term soil physical improvement in sustainable vineyard management. Full article

Alkali-activated fly ash geopolymers are promising low-carbon binders, but their performance depends strongly on mix proportion design. This study investigated the effects of water-to-binder ratio, sand content, and NaOH concentration on fly ash-based geopolymer using an L25(5⁶) orthogonal design. Flexural and compressive strengths were evaluated through range analysis and Analysis of Variance (ANOVA), while Random Forest was used as an exploratory tool for factor-response interpretation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were conducted to relate mechanical behavior to microstructural evolution. The optimal combination within the tested levels was a water-to-binder ratio of 0.30, sand content of 40%, and NaOH concentration of 12 mol/L. The maximum flexural and compressive strengths reached 3.65 MPa and 17.98 MPa, respectively. NaOH concentration dominated flexural strength, whereas water-to-binder ratio primarily controlled compressive strength. Model benchmarking and cross-validation showed that the machine-learning results had limited generalization capability under the small-sample condition and should be interpreted as candidate screening rather than independent predictive validation. Microstructural analyses indicated that strength development was associated with matrix densification, aluminosilicate network reorganization, and amorphous geopolymeric gel formation. Full article

A novel low-molecular-weight water-soluble oligosaccharide fraction (LBPP-1) was prepared from lotus bee pollen via microwave-assisted extraction, followed by Sevag deproteinization and diethylaminoethyl (DEAE)-cellulose-52 chromatography purification. Ion chromatography (IC) indicated a glucose-rich composition (84.6 mol% glucose), with minor amounts of arabinose, glucosamine, and galactose. Fourier transform-infrared spectroscopy (FT-IR), methylation analysis, and ¹H nuclear magnetic resonance (NMR) collectively supported the assignment of LBPP-1 as a glucan-rich, structurally heterogeneous oligosaccharide fraction containing candidate →4)-Glcp-rich domains and minor arabinose/galactose-related linkages. However, the marked difference between the IC composition and the sugar-type distribution estimated from PMAA peak areas limits quantitative interpretation of the residue proportions and branching architecture. Furthermore, in vitro biological assays demonstrated that LBPP-1 significantly attenuated lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 macrophages. It effectively reduced the secretion of nitric oxide (NO) and the levels of inducible nitric oxide synthase (iNOS), interleukin (IL)-6, and tumor necrosis factor (TNF)-α in RAW264.7 macrophages. Reverse transcription–quantitative polymerase chain reaction (RT-qPCR) analysis further revealed that LBPP-1 selectively suppressed the mRNA expression of cyclooxygenase-2 (COX-2), IL-1β, IL-6, iNOS, and transforming growth factor (TGF)-β1. These findings collectively suggest that LBPP-1, as a bioactive carbohydrate fraction derived from lotus bee pollen, holds promise as a natural functional food ingredient for managing inflammation-related conditions. Full article

This study focused on resistant starch (RS) from lotus, analyzing its content and structural characteristics across different lotus germplasms. Detection using the Dual-Wavelength Colorimetric Method revealed the following findings: The proportion of amylose in fresh lotus rhizomes was higher than that in fresh lotus seeds. The average content of resistant starch in fresh lotus rhizomes was also higher than that in fresh lotus seeds. After cooking, the resistant starch content of both lotus rhizomes and seeds decreased, with lotus seeds retaining a relatively higher amount of resistant starch post-cooking. Structural characterization showed that the surface of resistant starch from lotus seeds exhibited a grooved morphology, whereas that from lotus rhizomes appeared as irregular clusters. Additionally, the structure of raw resistant starch was more compact than that of cooked resistant starch. Fourier Transform Infrared (FTIR) Spectroscopy and X-ray diffraction (XRD) analyses confirmed that all lotus-derived resistant starches formed a type-C crystalline structure, with the crystallinity of resistant starch from lotus seeds being higher than that from lotus rhizomes. This study provides a theoretical foundation for breeding of high-RS lotus varieties and for the effective utilization of lotus germplasm. This work systematically compares RS composition and multi-scale structural differences between two edible lotus organs across a large germplasm population, clarifying the structural basis of RS variation, which distinguishes this study from previous single-material lotus RS research. Full article

This study used black soldier fly protein (BSFP) as a base material and added 0%, 1%, 2%, 3%, 4%, and 5% of grape seed anthocyanidins (GSAs) to prepare composite gels. Through the combined use of low-field nuclear magnetic resonance, Fourier transform infrared spectroscopy, scanning electron microscopy, and rheometry, the relationships among GSA dosage (0–3%), gel structural properties (secondary protein conformation, water status, and microscopic morphology), and rheological printability were systematically evaluated. It was found that the better GSA content fell within 1–3%, and under this condition the extrusion-type 3D printing performance of the composite gels was significantly enhanced. At a 3% addition amount, the proportion of disordered conformations decreased (random coiling decreased from 15.93% to 15.46%), the ordered structure increased (β-sheet increased from 35.25% to 35.43%), and deformation resistance was enhanced. Low-field nuclear magnetic resonance showed an increase in the proportion of non-flowing water and an increase in physical constraints. Scanning electron microscopy showed a reduction in pore size and a thickening of pore walls, forming a denser 3D network. Rheologic analysis indicated that 3% GSA reached the maximum zero-shear viscosity (η₀) and that the storage modulus (G′) and loss modulus (G″) were higher in the experimental group than those in the control group. Printing fidelity increased from 45.73% in the control group to 60.08% in the 1% group, 62.14% in the 2% group, and 71.05% in the 3% group (p < 0.05). The 3–5% groups (fidelity: 71.05–75.66%) all achieved hollow cylindrical printing without collapse and had excellent self-supporting performance. However, excessive addition (4–5%) caused excess GSA to adsorb onto the protein skeleton surface, reducing the apparent viscosity and damaging the printing performance. Based on all the indicators, the composite gel with 3% GSA achieved the best balance between printability and structural integrity. Our research offers a new idea for using flavonoid compounds to improve the 3D printing performance of insect protein gels. The prepared composite gels can be used as food printing inks and applied to personalized nutrition customization, functional food development, and sustainable protein alternative product fields. Full article