Search Results (307)

To address the widespread issue of abnormally high pump pressure during hydraulic fracturing of deep-to-ultra-deep reservoirs (burial depth > 4500 m) in the Junggar Basin, this study systematically reveals the mechanical mechanism underlying this phenomenon by integrating well logging curve analysis and elastoplastic mechanics theory. Statistical results demonstrate that the actual fracture initiation pressure of 60% of wells in the target block is significantly higher than the values predicted by traditional elastic theory, primarily attributed to plastic yielding and stress concentration effects around perforations induced by high in situ stress. An elastoplastic rock fracture initiation pressure model is established based on the Mohr–Coulomb criterion and the plastic zone radius criterion, which is applied to predict the fracture initiation pressure of selected wells in the target block. The relative error between the model predictions and field measurements is less than 2%, significantly improving the prediction accuracy of fracture initiation pressure in deep-to-ultra-deep formations. This provides precise guidance for subsequent optimization of operational parameters and selection of pressure ratings for wellhead equipment. The study further clarifies that in situ stress difference, rock yield stress, and the power-law hardening exponent are the key factors controlling the transition of fracture initiation modes. To mitigate the high pump pressure challenge in deep-to-ultra-deep reservoir fracturing, the field application of weighted fracturing fluid effectively increases the wellbore hydrostatic column pressure, reduces wellhead operational pressure, and ensures construction safety. The findings of this study provide critical theoretical and technical support for achieving the goal of “successful fracture initiation and effective fracture control” in deep-to-ultra-deep reservoir fracturing. Full article

Fractured coal in the residual-strength stage is a primary medium for gas migration and drainage in deep mining areas. To investigate the hydro–mechanical seepage response of post-peak fractured coal under constant-pressure-difference conditions, triaxial CO₂ seepage tests were conducted on coal specimens collected from the Xinyuan Coal Mine. A Weibull-based damage constitutive model was established to characterize the confining-pressure-induced hysteresis in the damage-evolution path. The flow-rate evolution and Reynolds number analysis indicated that gas flow remained within the linear Darcy regime. A controlled-variable analysis was used to examine the competing effects governing permeability evolution. Mechanical compaction induced an exponential decrease in permeability, whereas the decrease in permeability with increasing pore pressure was interpreted, within the proposed model framework, as the combined effect of possible adsorption-induced matrix swelling and weakened gas slippage. To address the limitations of conventional constant-slip-factor models, a pressure-dependent slip modulation coefficient was introduced into a composite permeability equation incorporating effective stress, adsorption-related deformation, and dynamic gas slippage. Global nonlinear fitting yielded R² = 0.97 and an RMSE of 0.1909, with the residuals generally distributed around zero, supporting the fitting reliability of the model within the investigated stress–pressure range. Response-surface analysis identified mechanical compaction as the dominant controlling mechanism, while adsorption-related deformation and gas slippage acted as secondary correction mechanisms. The proposed framework provides a quantitative basis for distinguishing the mechanical and fluid-related effects governing permeability evolution in post-peak fractured coal. Full article

Studying Bingham flows in permeable media under a periodic magnetic field enhances the understanding of yield-stress fluids for applications like oil recovery and filtration. This study combines non-Newtonian behavior with porous-medium resistance and magnetic variations, facilitating the analysis of complex flow phenomena, including oscillatory yielding and improved flow control in porous structures. The viscous potential theory is employed to streamline the mathematical processes. The utilization of linear governing partial differential equations of motion, along with appropriate nonlinear boundary conditions, yields additional simplifications. The investigation yields a nonlinear Mathieu oscillator that governs the interfacial displacement. A non-perturbative method is used to convert this nonlinear ordinary differential equation into a linear equation. A non-dimensional formulation minimizes the fundamental variables required to characterize the system by establishing a collection of dimensionless physical characteristics. The study analyzes a nonlinear Mathieu oscillator with complex coefficients to explore system dynamics related to elevation. By simplifying the variable coefficients, it enhances the examination of stability and resonance behavior. Despite inherent complexities, the work effectively clarifies fundamental concepts, contributing to a more coherent understanding of the subject. The Hartman number, magnetic field, and magnetic permeability ratio exert a destabilizing effect. Conversely, the Bingham parameter, Weber number, and periodic frequency exert a stabilizing influence. Full article

Exhaust piping in diesel engines is subject to severe thermal stress arising from high-temperature, high-pressure gas flows, and spray cooling with atomizing nozzles has become a widely adopted method to safeguard structural reliability. However, at present, the understanding of the spray fragmentation mechanism of two-phase flow under low inlet pressure is still not comprehensive. This study establishes a three-dimensional model of a gas–liquid impinging-jet nozzle and applies a coupled Volume-of-Fluid to Discrete-Phase-Model (VOF–DPM) approach to resolve the liquid breakup process in detail. High-speed imaging experiments were carried out to validate the numerical results. Orthogonal tests were conducted at five pressure levels for both gas and water—0.28, 0.24, 0.20, 0.16, and 0.12 MPa—producing 25 data pairs of spray cone angle and Sauter Mean Diameter (SMD). Within the 0–0.3 MPa air inlet pressure range explored here, raising the pressure consistently reduced the SMD and widened the cone angle, although both trends weakened as the pressure increased. Water inlet pressure exhibited a nonlinear influence, with local extrema appearing in the higher-pressure region. The overall SMD reached a minimum of 34.12 μm and a maximum of 149.04 μm. Using these 25 data points, a genetic algorithm was employed to optimize the pressure ratio under the constraint of total hydraulic power, yielding optimization strategies for different power budgets. An additional outcome of the simulation was the identification of a structural weakness: by reshaping the original flat impingement surface into a full conical surface, atomization quality improved by 29.36% under identical boundary conditions. These findings clarify the atomization mechanism of gas–liquid impinging jets under low inlet pressure and offer practical guidance for nozzle optimization. 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 study aims to systematically elucidate the influence of various heat treatment methods on the phenolic compounds in highland barley and their potential antihypertensive processes via chemical, in vitro bioactivity, and bioinformatics prediction analyses. This work employed UHPLC-Q Exactive HFX-MS/MS targeted metabolomics technology to ascertain metabolites in barley treated with five different thermal conditions: steaming (ST), boiling at atmospheric pressure (BO), boiling at high pressure (PO), extrusion puffing (EX), and sand-roasting (SR). The data revealed 252 phenolic metabolites, comprising 19 phenolic acids and 233 flavonoids. Moreover, it was observed that, in comparison to the untreated group, various heat treatments yielded substantial differences in the profiles of phenolic compounds. Notably, extrusion puffing (EX) exhibited superior performance: it increased specific flavonoid glycosides such as Clitorin and Quercetin 3-O-rutinoside-(1-2)-O-rhamnoside, while also improving direct antioxidant capabilities such as DPPH and FRAP. In addition, network pharmacology analysis of differentially expressed metabolites in the puffed group identified 44 potential targets, including TNF, IL-6, MMP-9, HIF-1A, and ACE. The KEGG and GO enrichment analyses revealed a substantial enrichment of these targets in classic hypertension-related pathways, including lipid metabolism, atherosclerosis and fluid shear stress. The molecular docking findings indicated that Apigenin 7-O-(2G-rhamnosyl) gentiobioside had significant binding affinities for the target proteins MMP9 and ACE. This study demonstrated that EX is an efficient processing method, with highland barley polyphenols showing potential antihypertensive activity. The findings provide a novel theoretical foundation and research direction for optimizing highland barley processing to maximize functional component utilization and elucidate its food-derived antihypertensive mechanisms. Full article

Cementitious materials in the fresh state are commonly regarded as viscoplastic. That is, below a given yield stress, they exhibit solid-like behavior, whereas above this threshold, they behave as fluids. In this context, the shear strength of such materials has traditionally been analyzed from a rheological standpoint, considering them as fluids and using time as the primary state variable. From a structural perspective, however, relatively few studies have treated the material as a solid. With the advent of 3D printing technology, this trend has persisted. Within this framework, the present research aims to evaluate the shear strength of a structural mortar for 3D printing in its solid-like regime, by applying the Mohr–Coulomb failure criterion. Furthermore, in a novel approach, the degree of hydration of Portland cement is proposed as a state variable to replace time, enabling a more comprehensive and objective description of the material’s mechanical evolution. Thus, addressing this gap in the state of the art, a chemo-mechanical coupling is developed. To obtain the necessary data, direct shear, uniaxial compression, and isothermal calorimetry tests are performed. The results indicate that the friction angle remains constant, at approximately 33°, and that cohesion, the parameter governing strength gain, exhibits the same linear rate of increase with hydration in both mechanical tests, indicating an intrinsic relationship within the material. Full article

The spatiotemporal evolution of seepage fields and the associated hydrodynamic risk of subsequent internal erosion pose a critical threat to the structural integrity of marine and hydraulic infrastructure. To quantify these complex fluid–solid interactions, this study develops a high-fidelity numerical model—coupling the Navier–Stokes equations with the Darcy–Forchheimer resistance model and the Volume of Fluid (VOF) method—to investigate transient hydrodynamics within porous foundations under complex geometric and geological boundary conditions. Parametric analyses reveal that spatial porosity distribution fundamentally dictates the system’s seepage capacity; notably, relocating a highly permeable stratum to the shallow sub-surface eliminates upper hydraulic bottlenecks and significantly escalates total volumetric discharge. Furthermore, the study systematically evaluates the hydrodynamic efficacy of multi-dimensional seepage control structures. Results demonstrate that while increasing the vertical depth of a cutoff wall is highly efficient in restricting bulk volumetric flux, it inadvertently induces intense localized streamline convergence and flow acceleration at the structural tip. Conversely, lateral expansion of the wall base, though yielding only a moderate reduction in total seepage, successfully diffuses this concentrated flow and substantially attenuates peak pore fluid velocities. Ultimately, a combined design paradigm is proposed for practical coastal engineering applications: prioritizing vertical penetration to optimize bulk seepage reduction, concurrently integrated with moderate lateral base expansion to redistribute concentrated hydrodynamic shear stresses, thereby minimizing the hydrodynamic potential for localized piping and ensuring long-term stability against seepage-induced degradation. Full article

Engineered geothermal system (EGS) cross-well flow of 30 L/s producing heat at a rate of Q~20 MW for 30 days was achieved by the UtahForge project in 2024. The cross-well flow doublet measured ℓ~400 m in length at L~100 m vertical offset. A first-order question is how sustainable the doublet’s 20 MW heat extraction is. Where once the answer would be framed in terms of pipe-like cubic-law flow along stress-aligned fault-scale planar heat exchange surfaces, UtahForge flow data rule out this heat exchange picture. The EGS flow data indicate aquifer-like volumetric cross-well flow with heat exchange at the grain scale. More specifically, the EGS flow data indicate no cross-well flow for a dozen hydrofrack attempts, while the 30 L/s flow occurred when the 400 m doublet wells were rendered effectively open to the crustal formation by drilling out all hydrofrack gear. An essential further observation is that the producer well flowed at only 70% of the injector rate: 30% of injected fluid was lost to flow heterogeneity in the cross-well volume. A four-step deconstruction of these observations explicitly characterizes the flow heterogeneous volume: (i) flow stimulation of the cross-well volume, (ii)wellbore-centric flow in/out of cross-well volume along the 400 m open well reach, (iii) heat advection in the cross-well volume, and (iv) sustainability-specific heat conduction into the cross-well volume. EGS stimulation process step (i) is attested by microseismic emissions (Meqs) registered on downhole sensors. Meq size and spatial correlations in turn reflect the flow heterogeneity of the cross-well volume. EGS step (iv), crustal heat conduction sustainability, is approximated by assuming radial heat energy extraction at rate Q/ℓ by a central line-sink of radius R < L/2. The line-sink analytic solution yields heat reservoir sustainability of ~3–10 years. Greater sustainability at Q/ℓ rate requires larger cross-well offsets L. The intimate relation between fluid flow and seismic emissions enables downhole seismic sensor data to image EGS flow stimulation activity. The future of EGS heat extraction depends to a large degree on feasible sizes of cross-well offset L in the flow-heterogeneous crust. Full article

Wheel hubs in heavy-duty agricultural trailers operate under demanding conditions comprising rough terrain, impact loads, and highly variable load spectra. Current design practice relies predominantly on experience-based sizing rather than systematic multi-physics analysis. This study presents an integrated design methodology combining finite element analysis (FEA), density-based topology optimisation, and computational fluid dynamics (CFD) to concurrently improve the structural and tribological performance of a GGG40 spheroidal graphite cast iron agricultural trailer wheel hub. A reference commercial hub geometry was modelled and analysed under multiple load conditions with a safety factor of 5. Critical stress regions were identified, and the free design volume was optimised while preserving all functional surfaces. The optimised design achieved 35% mass reduction (14.9 to 9.6 kg), 30% lower maximum von Mises stress (235 to 165 MPa), and up to 40% stress reduction in the bearing seat region. Oil-circulation channels integrated into the bearing housing raised mean lubrication flow velocity by 28% and eliminated stagnation zones, yielding a more homogeneous oil-film distribution and directly benefiting bearing tribological performance. The proposed framework provides a manufacturable engineering methodology that concurrently addresses structural integrity and lubrication performance in agricultural wheel hub design. Full article

Real-Time In-Line Monitoring (RTIM) of rheological properties such as slurry yield stress is important in different industries for its various benefits such as significant time savings and increased safety/efficiency of processes while reducing secondary waste due to sampling or inaccurate procedures. This paper discusses two methods for characterizing yield stress in real time: the Pressure Loss method and the Liquid Rise method. The Liquid Rise method uses the height of the slurry in a vertical column and the pressure difference to quantify the yield stress. The Pressure Loss method uses the drop of pressure in a laminar flow of slurry to determine the yield stress. Kaolin–water slurry is used as a simulant of the non-Newtonian fluid. An experimental setup is built to demonstrate the methods, and data obtained from the experimental setup is compared with the yield stress obtained from a conventional table-top rheometer (baseline rheology). The results show a good agreement between the experimental yield stress and baseline rheology. Full article

The marine benthic invertebrate Urechis unicinctus exhibits extraordinary tolerance to hypoxic environments, making its coelomic fluid a unique and promising biological source for discovering novel stress-adapting macromolecules. Polysaccharides derived from the coelomic fluid of U. unicinctus were systematically extracted, fractionated, and characterized to investigate their structural features and associated biological activities. Gradient ethanol precipitation (30–80%) combined with DEAE-52 ion exchange chromatography yielded twelve fractions with distinct physicochemical properties. Significant variations were observed in molecular weight (10³–10⁵ Da), sulfate content (3.77–24.26%), and monosaccharide composition. High-ethanol fractions, particularly U68P and U18P (extracted at 60 °C and 100 °C, respectively, and both precipitated with 80% ethanol), were enriched in low-molecular-weight, highly sulfated heteropolysaccharides composed of galactose, fucose, glucosamine, and ribose. These fractions exhibited superior antioxidant activities, including strong scavenging effects against DPPH, ABTS, and hydroxyl radicals. Moreover, they demonstrated pronounced neuroprotective effects in the oxygen–glucose deprivation/reoxygenation (OGD/R) model using SH-SY5Y cells, significantly improving cell viability. Structure–activity relationship analysis revealed that reduced molecular weight, increased sulfation degree, and more diverse monosaccharide composition (e.g., more diverse monosaccharide composition) synergistically contribute to improved bioactivity by facilitating cellular uptake and exposing functional groups. In contrast, high-molecular-weight homoglucan fractions showed relatively weak effects. Overall, this study identifies U. unicinctus coelomic fluid as a promising source of bioactive polysaccharides and provides a theoretical basis for the development of marine-derived anti-hypoxic and antioxidant agents. Full article

Background: Exposure to anthropogenic and/or natural (e.g., herbicides or mycotoxins) endocrine-disrupting chemicals (EDCs) has been linked to several reproductive disorders. Glyphosate (GLY), a common agricultural agent, is a potential element of the exposome that bioaccumulates and has potential endocrine and oxidative stress-related effects. However, data on its presence in the human ovarian microenvironment remain limited. Our study examined GLY levels in follicular fluid (ff) and serum and their relationships with oxidative stress markers, reproductive hormones, and stress hormones in women undergoing in vitro fertilization (IVF). Methods: 50 women undergoing controlled ovarian stimulation participated. Serum and ff samples were routinely collected during oocyte retrieval. GLY, related hormones (e.g., cortisol, estradiol-E2, anti-Müllerian hormone-AMH, and melatonin-MT), an oxidative stress marker malondialdehyde (MDA), antioxidant enzyme activities, total antioxidant capacity, and co-occurring natural pollutant mycotoxin levels were measured. Relationships between GLY levels and these mediators were assessed using correlation and regression analyses. Results: GLY was detected in both serum and ff at similar concentrations (0.038 ± 0.006 ng/mL vs. 0.045 ± 0.006 ng/mL; p = 0.414). Follicular GLY levels showed a positive association with MDA (Spearman’s r = 0.4487, p < 0.001), explaining 28.6% of the variability in follicular MDA. Serum GLY was positively associated with serum (β = 40.26, p = 0.0058) and follicular E2 (r = 0.29, p = 0.042). Serum GLY levels were negatively correlated with cortisol (β = −0.0188, p = 0.020). A slight correlation between follicular GLY and MT was observed (p = 0.03). No associations were found between GLY levels and age, body mass index, AMH, the recombinant gonadotropin dose used, antioxidant enzyme activities, follicle count, oocyte yield, or embryo viability. Conclusions: This study might be the first to demonstrate the presence of GLY of exposome in human ff, indicating that environmental exposure to GLY may reach the oocyte microenvironment. The correlation with lipid peroxidation suggests GLY could contribute to follicular oxidative stress. The associations with E2 and cortisol point to potential endocrine-disrupting effects. While no direct impact on IVF outcomes was observed, findings suggest low-level exposure to GLY could influence ovarian physiology through specific biochemical mechanisms. Full article

Accurate prediction of aggregation in suspensions is crucial for diverse engineering applications. This paper develops a sequential theoretical strategy, based on tunnel theory, to predict the aggregation configuration in magnetic compound fluids (MCF) by evaluating their volume concentration C_v. We formulated the viscosity η, resistance R, and capacitance C resulting from aggregation as functions of C_v. This involved a theoretical procedure using tunnel theory, refined using experimental data, including vertical force F_v arising from the concentration gradient, as well as electrical conductivity σ and permittivity ε. The theoretical formulation for η was further refined by considering hypothetical aggregation configurations, specifically non-uniform particle distribution and agglomerations approximated as spheroids with axis ratio κ, along with experimental data on shear flow. For R and C, the formulations were refined using experimental data for σ and ε, together with the relationship between C_v and the applied magnetic field H_v derived from tunnel theory and F_v. This sequential theoretical analysis yielded final formulations for η, R, and C as functions of H_v and initial volume concentration C_v,o. Specifically, η was expressed as a function of κ and C_v,o for the shear and stress–shear strain γ’ relationship under conditions of H_v < 200 mT, 11 < C_v,o < 30 vol.%, and γ’ < 300 1/s. R and C were determined under conditions of H_v < 150 mT and 11 < C_v,o < 30 vol.%. These findings pave the way for novel theoretical predictions of C_v, R, and C based solely on H_v data, a capability crucial for designing diverse materials. Full article

The reliability of structural safety assessments for offshore wind turbines is often compromised by time-dependent corrosion effects and the high computational cost of fluid–structure interaction analysis. This study proposes a data-driven framework for predicting the degradation of offshore wind turbine support structures under time-dependent corrosion. First, the multi-faceted mechanisms of corrosion progression were analyzed to quantitatively evaluate the evolution of structural cross-sectional damage and residual load-bearing capacity. A structural mechanical equivalent method was then proposed and integrated with a high-fidelity fluid–structure coupled model that takes into account corrosion effects, and a corresponding time-dependent structural response database was established. Then, the data extrapolation techniques were applied to unsimulated response samples, enabling comprehensive assessment and accurate forecasting of structural states. Validation under different data sampling strategies shows that the dense strategy achieves the highest accuracy, with stress and deformation errors of 0.31% and 2.23%, the moderate strategy yields errors of 2.47% and 2.58%, while the sparse strategy results in larger errors of 3.31% and 8.71%, but still captures the overall evolution trend. It demonstrates that the proposed approach provides a reliable and efficient predictive tool for service-life assessment and structural response evaluation of offshore wind turbine support structures. Full article