Search Results (123)

Urban drainage overflows can release a large fraction of event-scale pollutants during the early stage, yet current control remains largely driven by hydraulic signals rather than pollutant-release dynamics. This study created a dissolved organic matter (DOM)-based fluorescence fingerprint method to precisely identify the shift from pollutant flushing to dilution or ongoing input, helping determine the timing of first-flush transitions and potential interception. Fourteen wet-weather overflow events from seven drainage systems in Shanghai and Changzhou were investigated using excitation–emission matrix fluorescence spectroscopy, combined with non-negative matrix factorization, random forest feature screening, principal component analysis, mass–volume (M(V)) curve analysis, and Pettitt change-point detection. Five macro-scale fluorescence fingerprints were resolved, representing protein-like, fulvic-like, and humic-like components. Protein-like fingerprints dominated rapid event-scale variations, while fulvic-like and humic-like fingerprints reflected continuous surface-derived input and stable background contribution, respectively. Peak-shift trajectories revealed three fluorescence-evolution modes: directional red-shift migration, peak-position stability, and weak, non-directional variability, reflecting different source-release dynamics and DOM compositional adjustments during overflow. Random forest screening identified 20 high-importance fine-scale fluorescence fingerprints, with 90% concentrated in protein-like regions linked to sewage-derived and labile DOM. Compared with macro-scale fingerprints and conventional water quality indicators, fine-scale fluorescence fingerprints showed clearer stage separation, stronger consistency with M(V)-based cumulative response patterns, and more distinct first-flush interception timing. This timing marked the transition from early concentrated pollutant release to dilution or sustained input, whereas macro-scale fingerprints indicated broader transition intervals and conventional indicators showed delayed responses. These findings highlight the potential of fine-scale fluorescence fingerprints to support future fluorescence-assisted overflow control by improving transition identification and targeted interception decisions. Full article

To achieve safe mining and precise gas control in Liuzhuang Coal Mine, the dynamic evolution of mining-induced overburden fractures at the 150,502 working face was systematically investigated via theoretical analysis, FLAC3D numerical simulation, and field measurements. A 3D model (600 m × 300 m × 154 m) was established to simulate the plastic zone, displacement, and stress fields during face advancement from 50 to 400 m. Strata damage modes were evaluated, and the “two zones” heights were determined based on plastic criteria. The results show that fracture development exhibits distinct stages. The plastic zone displays a “spoon-shaped” distribution, with damage more concentrated on the open-off cut side than the working face side. The caving zone height is approximately 12 m, and the maximum fractured zone height reaches 60 m. Based on key strata theory, a 7 m thick fine sandstone layer 24–31 m above the roof acts as the key stratum controlling overburden deformation, offering stable lithological conditions for gas accumulation and borehole integrity. Field monitoring of cross-stripping boreholes demonstrates that the No. 6 drilling site at the 25 m horizon achieves the highest gas extraction concentration of up to 11%, significantly outperforming the 15 m and 20 m horizons. By integrating multiple methods, the optimal horizon for large-diameter directional boreholes is finalized at 24–31 m, providing a reliable scientific basis for efficient gas drainage under contiguous extra-thick coal seam mining conditions. Full article

Gas concentration in coal mine return-air corners is affected by ventilation, mining disturbance and gas drainage conditions, and it shows strong nonstationarity, local fluctuation and dynamic multi-point correlations. To improve frequency information separation, monitoring point relationship modeling, and short-term prediction accuracy, a variational mode decomposition (VMD)-based dual-branch spatiotemporal graph method is proposed. Gas concentrations from four key monitoring points are used as inputs, and the return-air corner gas concentration is taken as the output. First, the raw series are decomposed by VMD and reconstructed into low- and high-frequency components. Then, two branches are built for different frequency components. The low-frequency branch combines adaptive graph learning, graph convolution and gated recurrent units to extract global variation features, while the high-frequency branch combines graph attention and gated recurrent units to capture local disturbance features. Finally, a feature-fusion module generates multi-step predictions, and a lightweight short-term warning strategy is developed based on the predicted values. The proposed model achieves MAE, RMSE and R² values of 0.0338, 0.0471 and 0.9499 in one-step prediction, respectively, and outperforms GRU, LSTM, GCN-GRU, GAT-GRU, VMD-GRU, Informer and STGCN under three-step and six-step conditions. Cross-dataset validation and inference time analysis indicate good adaptability and online prediction potential. Full article

Aging and deterioration of urban underground drainage pipelines frequently trigger road collapses, urban waterlogging and groundwater contamination, posing critical challenges to the operation, maintenance and disaster prevention of urban underground infrastructure. Conventional rehabilitation solutions, including cement-based linings and traditional polymer liners, suffer from inherent limitations such as reduced effective flow cross-sections caused by excessive lining thickness, unsatisfactory corrosion resistance and durability, and high construction disturbance. In this study, a modified polyurea (MPU) material was applied to the trenchless rehabilitation of drainage pipelines via spray-applied pipe lining technology. The mechanical properties and interfacial bonding performance of MPU were systematically characterized at the material scale; full-scale external pressure tests were conducted to investigate the effects of 3–8 mm thick MPU linings on the bearing capacity and failure characteristics of structurally damaged concrete pipes; and the anti-seepage repair performance for local perforation defects was evaluated through void-crossing testing. The results demonstrate that MPU lining can meet the engineering performance requirements for pipeline rehabilitation when applied with matched interfacial primer following standard construction procedures. Even the baseline bond strength tested without primer remains sufficient to ensure stable cooperative load bearing between the lining and the host concrete pipe. The 3–8 mm thick linings increase the cracking load of damaged pipes by 61.7–145.7% and the ultimate load by up to 162.2%, while transforming the failure mode from brittle fracture to ductile failure. For local perforation repair, the 3 mm thick MPU lining achieves a critical hydrostatic failure pressure of 1.23 MPa, maintaining favorable structural integrity and interfacial bonding stability under the test conditions. With a well-balanced combination of thin lining thickness, rapid curing and high structural strengthening efficiency, as well as favorable inherent corrosion resistance, the MPU lining provides novel material alternatives and fundamental experimental evidence for the green trenchless rehabilitation of aged underground pipelines and offers technical support for the safe operation and maintenance of urban underground infrastructure. Full article

This paper investigates folding as a practicable design methodology in response to the combined requirements of complex sites and public programs. A sloped waterfront community theater in Boston is used as a test case, where a parametric workflow in Rhino/Grasshopper is employed to translate continuous surfaces, via panelization, into buildable systems constrained by curvature and developability. In the Boston community theater case study, diamond panels are employed for the primary enclosure and seating; stepped panels organize circulation across the slope; and triangular closures resolve edge conditions and tolerances. Fold lines simultaneously function as legible paths, stitching exterior and interior into a continuous sequence. Parameters are used to align lines of sight, gradients, and drainage with structural supports, thereby demonstrating a traceable linkage from geometry to construction and operation. The findings reveal that folded geometries establish continuous linkages among topography, circulation, and program; that fold lines function as force paths, drainage organizers, and edge closures; and that interstitial layers between folded interfaces facilitate transitions between performance and everyday modes, thereby sustaining public use. The study proposes a reusable “folding–parametric–panelization–structural integration” framework, providing a transferable technical pathway for community-scale public architecture. Full article

The Huainan Mining Area features extensively developed, fragmented-soft and low-permeability coal seams, characterized by low porosity and permeability, complex geological structures, and significant difficulty in coalbed methane (CBM) drainage. Horizontal wells with staged fracturing in the coal seam roof have become a key method for regional gas control. To further enhance the volume fracturing stimulation effect and single-well gas production, this study targets the horizontal well group in the roof of the No. 8 coal seam in the Huainan Mining Area as the research object. A saturated volume fracturing technology for horizontal wells in the coal seam roof, centered on the concept of a high pump rate (18–20 m³/min) and a high proppant volume (>250 m³/stage), is proposed. This study investigates the fracture propagation mechanisms and fracturing parameter optimization of this technology, and conducts engineering application to verify its stimulation effect. Increasing the fracturing pump rate improves the proppant-carrying capacity of the fracturing fluid, successfully enabling high-rate and high-volume proppant placement. Optimization of the perforation parameters—12 holes per m per cluster and a cluster spacing of 15–25 m—utilizes high perforation friction and moderate stress interference to promote balanced initiation and propagation of multiple fractures within a stage. The optimized ‘saturated’ injection mode, with a single-stage fluid volume exceeding 2400 m³, a single-stage proppant volume exceeding 250 m³, and a maximum sand ratio exceeding 20%, combined with a multi-size proppant mixture, enables full propping of both main and branch fractures. Microseismic monitoring shows that the hydraulic fracture extension length increased by approximately 50% compared to conventional wells, significantly enlarging the stimulated reservoir volume (SRV). Saturated fracturing achieved stable gas production of 2000 to 3000 m³/d, with average production ramp-up rates of 21.47–26.40 m³/d (five times higher than the 5.34 m³/d of the conventional well), and the stable plateau period was notably extended from 36 days to over 150 days. The saturated volume fracturing technology proposed in this study provides an important reference for efficient CBM extraction and surface gas control in mining areas with similar geological conditions. 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

Salt cavern Compressed Air Energy Storage (CAES) is one of the critical technologies for energy storage and an important infrastructure supporting the construction of new power systems and facilitating the achievement of the dual carbon goals. The salt rock resources in China are primarily composed of continental strata salt rocks, characterized by high heterogeneity, well-developed thin-layer interbedding, dissolution resistance among different lithologies, and significant creep variations. These features, to some extent, limit the improvement of wellbore construction accuracy, the reliability of abandoned well sealing, the safety of natural gas storage operations, and enhancements in gas injection–brine displacement efficiency. This study takes the continental bedded salt rock in the Dawenkou Basin as the research object and adopts a method combining theoretical analysis and field engineering verification to improve the systematic construction technology system, covering the whole process of drilling engineering, abandoned well plugging, the design of an injection and brine extraction device, and gas injection and brine drainage. The research results optimize four key technologies, including precise wellbore trajectory control, dual-section milling, and multi-stage redundant plugging of abandoned wells and long-term anti-corrosion completion with laser cladding, and dual-mode adaptive gas injection and brine drainage, and improve the technical system from wellbore construction to salt cavity formation. This study can provide valuable theoretical references and engineering demonstration guidance for underground space development projects in similar salt basins in China. Full article

Phenolics in Sphagnum can inhibit its microbial decomposition. Climate warming and drainage have driven vascular plants, such as Ericaceae, to expand into Sphagnum-dominated peatland. However, the impact of fine root invasion by Rhododendron auriculatum Hemsl. on Sphagnum decomposition and changes in phenolic compounds remains unclear. This study compared Sphagnum decomposition in a Sphagnum palustre L.-dominated peatland and an R. auriculatum (Sapling)–S. palustre peatland by examining the microscopic structure of S. palustre and microbial community composition. Decomposition was higher in the R. auriculatum–S. palustre peatland. On this site, bacterial metabolic types such as aerobic chemoheterotrophy and chemoheterotrophy had higher relative abundances, as did fungal trophic modes, including those with combined ectomycorrhizal, ericoid mycorrhizal, and saprotrophic functions. Acid phosphatase, laccase, total nitrogen (TN), C/N ratio (C:N), and pH differed significantly across decomposition stages. Microbial communities are affected by physicochemical factors and enzyme activities. Untargeted metabolomics revealed more downregulated than upregulated phenolics, cinnamic acids, and tannins, indicating loss of phenolic compounds. In summary, R. auriculatum fine root invasion altered enzyme activities and physicochemical properties, driving the restructuring of bacterial and fungal trophic modes and accelerating S. palustre cell wall and hyaline cell decomposition. Full article

Road drainage infrastructure in ENSO-vulnerable Andean regions faces compounding threats from climatic variability, geometric inadequacy, and systemic maintenance neglect. This study presents a STEM-integrated Project-Based Learning (PjBL) diagnostic framework applied to 42 road segments along corridors connecting Loja, Ecuador, selected through a purposive-stratified spatial-coverage protocol. Using ArcGIS Survey123, standardised field data were collected on structure presence, geometry, failure modes, and condition across four structure types: crown gutters, road gutters, hydraulic chutes, and culverts. The Composite Drainage Deficiency Index (DDI, 0–100) was derived from five equally weighted binary indicators and validated through Monte Carlo Dirichlet weight-perturbation analysis and jackknife leave-one-out resampling, confirming rank-order invariance to admissible alternative weightings. The results reveal severe systemic deficiencies, including crown gutters absent at 88.1% (95% CI: 75.0–94.8) and road gutters at 81.0% (95% CI: 66.7–90.0) of sites. Every segment exhibited at least one drainage failure (100%; 95% CI: 91.6–100). The DDI identified 73.8% of segments in the High or Critical band (DDI ≥ 60; mean = 60.2 ± 20.4). Hierarchical clustering isolated one geometric outlier whose exclusion altered the aggregate metrics by <1.2%. These findings establish a georeferenced baseline for maintenance prioritisation and validate the methodological reproducibility of academically integrated field protocols for infrastructure diagnostics. Full article

During underground mining, the stability of in-seam gas drainage boreholes is jointly affected by multiple factors, including the in situ stress state and borehole structure. Borehole instability can reduce gas drainage efficiency and increase underground safety risks. Among these factors, confining pressure plays a decisive role in the damage evolution of the coal surrounding the borehole. To clarify the damage evolution characteristics of the coal surrounding the borehole under different confining pressure conditions, conventional triaxial graded cyclic loading–unloading numerical simulations were conducted on borehole-containing specimens using PFC2D software (version 6.0). The effects of confining pressure on acoustic emission (AE) ringing counts, microcrack propagation, crack angle distribution, damage evolution, and failure characteristics were systematically analyzed. The results show that, under graded cyclic loading–unloading, the peak AE ringing count of the borehole-containing specimens first increases and then decreases with increasing confining pressure, whereas the cumulative ringing count continues to increase. The spatial distribution of microcracks gradually evolves from dispersed development to concentration around the borehole, and the crack propagation path changes from single-path dominance to coordinated multi-path propagation. The angular distribution of tensile cracks exhibits a non-monotonic evolution pattern, namely, dispersion, concentration, and weakening, with increasing confining pressure, whereas the distributions of shear cracks and total cracks show a gradually broadened unimodal pattern with enhanced connectivity between angular intervals. At the final failure stage, both the tensile damage ratio and the shear damage ratio increase with increasing confining pressure, and their difference increases from 0.24% to 0.90%, indicating that increasing confining pressure further strengthens the dominant role of shear damage. The failure mode gradually evolves from tensile–shear mixed failure toward relatively shear-dominated failure. The results provide a theoretical basis for analyzing borehole instability and failure characteristics under different confining pressure conditions, as well as for optimizing grouting-based borehole protection parameters. Full article

Mountainous megacities face a distinctive form of pluvial waterlogging in which terrain-controlled flow convergence, accelerating imperviousness, and aging drainage interact to produce chronic, spatially clustered failures rather than stochastic events. Existing frameworks, such as hydrodynamic modeling, data-driven machine learning, and multi-criteria composite indexing, carry distinctive failure modes at the municipal scale. This study develops and externally validates a city-wide, grid-based assessment framework for Chongqing, China, through three integrated choices. First, resilience is reformulated as a stabilized adaptation-to-risk ratio and subjected to an explicit falsification test against independent waterlogging observations. Second, multi-source hydroclimatic, topographic–hydrologic, land-cover, and service-accessibility indicators are integrated on a 500 m fishnet (22,500 cells) through within-component CRITIC–Entropy weighting and TOPSIS, with robustness diagnosed by a 500-iteration Monte Carlo weight-perturbation analysis. Third, a spatially grouped LightGBM classifier with SHAP interpretation serves both as an independent validation layer and as a mechanistic lens on non-linear driver thresholds. The composite risk surface achieves ROC-AUC values of 0.834 and 0.873 against two independent waterlogging registries, is strongly spatially clustered (Moran’s I = 0.81, p < 0.001), and preserves its ranking under aggressive weight perturbation (Spearman ρ ≥ 0.95 in 95% of scenarios). A counterintuitive finding emerges from the falsification test as resilience yields ROC-AUC below 0.5 on both point sets, indicating that accessibility-based capacity proxies systematically capture urban centrality rather than drainage robustness, like a diagnosable measurement problem affecting the wider resilience-index literature. LightGBM concentrates 88.0% of waterlogging cells within the top 10% of scored grids, and SHAP-derived thresholds align with saturation-ponding, well-drained, and convergence–hotspot regimes of classical hydrology. Together, these results reframe waterlogging assessment in complex terrain from a cartographic exercise into a falsifiable, resource-aware prioritization framework, and clarify why capacity maps and risk maps should be published as complementary instruments of flood governance. Full article

The development of high-viscosity oil fields requires technologies that provide not only the thermal mobilization of oil, but also an economically justified level of production with a high energy intensity of the process. One of the most effective technologies of this type is steam-assisted gravity oil drainage (SAGD), but its practical effectiveness is determined by the combined influence of reservoir geology, heat-transfer parameters, and market conditions. The paper proposes a reduced physics-guided model for the rapid technical and economic screening of SAGD in high-viscosity oil fields. The methodological contribution lies in linking geological screening, steam energy input, useful heat delivered to the reservoir, production response, and operating profit within one interpretable analytical chain suitable for pre-feasibility assessment. The study is based on an extended-scenario thermoeconomic analysis of representative heavy-oil development conditions. It is shown that, in a favorable mode, at a depth of about 400 m, oil viscosity of 15,000 cP, steam consumption of 500 t/day and heat-transfer coefficient of 0.7, the estimated production reaches 513–520 t/day, and the net profit is 20,000–22,000 USD/day. In an unfavorable mode, with a depth of about 1000 m, a viscosity of 20,000 cP, a heat-transfer coefficient of 0.4, and a high steam cost, production decreases to 210–230 t/day, and the economic result becomes negative. It has been established that the cost of steam, heat transfer, and the price of oil have a decisive impact on profitability. Full article

Hollow auxetic structures enable lightweight mechanical design by reducing mass while preserving architected deformation. However, hollow auxetic studies focus on LPBF metals. This study presents a manufacturing-constrained design and validation framework for a hollow hybrid re-entrant chiral lattice produced by stereolithography. The unit cell was parameterised by chiral angle, re-entrant strut length, and hollow internal diameter, with drainage features integrated into the CAD model to preserve hollow channels during printing and post-processing. A minimum internal diameter study defined the printable design window. Within these limits, a central composite design coupled with finite element analysis mapped the response surface and identified an optimised geometry of θ = 15°, L = 3.5 mm, and d = 1.68 mm, with a predicted unit-cell negative Poisson’s ratio of about −1.17. Compression testing confirmed that the printed unit cell and 3 × 3 × 3 lattice retained the intended rotation-dominated auxetic deformation mode. At the selected comparison strain, the unit cell showed a negative Poisson’s ratio of −0.68 and the 3 × 3 × 3 lattice showed −0.29. Relative to the solid lattice, the hollow lattice reduced density by 42.4% with only a 3.0% reduction in stiffness, increasing specific stiffness by 68.9% and specific peak strength by 5.2%, but reducing specific energy absorption by 25.6% due to earlier localisation and junction driven fracture. These results provide practical design guidance for manufacturable hollow SLA auxetic lattices, especially for lightweight and stiffness-limited applications where low mass and high specific stiffness are more important than energy absorption. Full article

Necrotizing (abscessing) lymphadenopathy is a clinically relevant condition with a broad differential diagnosis, including acute bacterial infections, mycobacterial disease, zoonoses, fungal and parasitic infections, autoimmune disorders, and malignancies with central necrosis. Early and reliable differentiation between these causes is important to avoid misdiagnosis and to guide appropriate therapy. This review summarizes the pathophysiological mechanisms, typical imaging features, and diagnostic value of contrast-enhanced ultrasound (CEUS) in necrotizing lymphadenopathy. Representative clinical vignettes illustrate the disease spectrum and correlate CEUS patterns with underlying pathology. The literature review was narrative and based on targeted searches of PubMed/MEDLINE and Google Scholar focusing on CEUS in necrotizing lymphadenopathy. A brief literature overview highlights current evidence, limitations, and research gaps. Conventional B-mode ultrasound (BMUS) and Doppler typically demonstrate enlarged hypoechoic or heterogeneous nodes with reduced central vascularity but lack specificity for necrosis. CEUS provides real-time visualization of nodal microvascular perfusion, which may support clearer differentiation between viable tissue and necrotic or abscess cavities. Common but non-specific CEUS patterns include central non-enhancement with a peripheral hyperemic rim in abscesses, irregular avascular cores in tuberculous lymphadenopathy, patchy non-enhancing areas in autoimmune conditions, and heterogeneous enhancement with ill-defined necrosis in malignant nodes. CEUS can support biopsy targeting, facilitate drainage procedures, and enable radiation-free follow-up. CEUS may offer diagnostic and interventional advantages in the evaluation of necrotizing lymphadenopathy, offering more consistent characterization of nodal necrosis compared with conventional sonography. While most evidence focuses on tuberculosis and malignancy, growing experience with zoonotic and autoimmune diseases suggests broader utility. Most currently available evidence derives from observational studies and small case series, highlighting the need for prospective multicenter validation. Standardization of CEUS criteria, integration into multiparametric ultrasound protocols, and multicenter validation are needed to establish CEUS as a routine component in the diagnostic work-up of necrotizing lymphadenopathy. Full article