Search Results (2,849)

In this study, deep tight sandstone was selected as an example to propose a complete method for predicting reservoir pore structure by capillary pressure curves and conventional well log data. This method pioneers the integration of grey relational analysis, principal component analysis, ensemble clustering, and deep neural networks to establish a systematic predictive framework for transitioning from conventional logging data to pore structure types. A total of 186 core data from three wells were used in this study. First, sensitive pore structure parameters from mercury injection capillary pressure data were extracted using grey correlation analysis and principal component analysis. Then, unsupervised clustering analysis was applied to classify the reservoir pore structures in the study area, dividing it into three categories. These category labels were combined with conventional well logs to create learning samples for a deep neural network (DNN) model developed to predict reservoir pore structure categories. The accuracy of the training set of the model reached 88.2%, while the accuracy of the testing set was 80.43%. Finally, the method was applied to field well log data. The results showed significant differences in pore structure classifications among gas layers, water–gas layers, and dry layers. This method is versatile, with its core components transferable to other deep sandstone reservoir studies, and can accurately predict the pore structure of tight sandstone reservoirs, which is critical for advancing the characterization of deep and complex oil and gas reservoirs. Full article

KIT-6 samples were prepared at hydrothermal aging temperatures of 60, 100, and 140 °C, and used as templates for nanocasting of zirconium-doped ceria. In nanocast samples, the ordered 3D structure collapsed, leaving behind nanorods with a diameter roughly in concordance with the corresponding KIT-6 template pore diameter. In addition to nanocrystalline ceria, a small amount of cubic zirconia is present in the doped samples, but the formation of a solid solution was confirmed by the decrease in the ceria lattice parameter relative to bulk ceria. The specific surface areas of the nanocast samples decreased with the increase in KIT-6 template aging temperature. Ceria bandgap values were slightly blueshifted in comparison with bulk ceria, which was attributed to quantum confinement. No difference between samples concerning lattice ceria defects has been noted. Conversion curves show apparent three-stage conversion with stagnation at temperatures in the range between 250 °C and 300 °C, which is a consequence of abundant adsorption of toluene below 250 °C and desorption above 250 °C. Slight differences in catalytic activity are only due to a difference in the amount of adsorbed toluene caused by differences in the specific surface area of the samples. Full article

This paper presents an analytical model for one-dimensional consolidation analysis of multi-layered unsaturated soils under depth-dependent initial conditions. The general solutions are derived explicitly using the Laplace transform. By combining these general solutions with interfacial continuity conditions between layers and the boundary conditions, the reduced-order system is solved via the Euler method to obtain analytical solutions in the Laplace domain. Numerical inversion of the Laplace transform is then performed using Crump’s method to yield the final analytical solutions in the time domain. The model incorporates initial conditions that account for both uniform and linear distributions of initial excess pore pressure within the soil stratum. The proposed solution is verified by reducing it to degenerated cases (e.g., uniform initial pressure) and comparing it with existing analytical solutions, showing excellent agreement. This confirms the model’s correctness and demonstrates its generalization to multi-layered systems with depth-dependent initial conditions. Focusing on a double-layered unsaturated soil system, the one-dimensional consolidation characteristics under depth-dependent initial conditions are investigated by varying the physical parameters of individual layers. The proposed solution can serve as a theoretical reference for the consolidation analysis of multi-layered unsaturated soils with depth-dependent initial conditions. Full article

Carboxymethyl hydroxypropyl cellulose (CMHPC) combines the advantages of both carboxymethyl and hydroxypropyl substitutions, exhibiting superior solubility, viscosity characteristics, and enhanced salt tolerance compared to carboxymethyl cellulose (CMC). This study presents an optimized synthesis route for CMHPC through homogeneous hydroxypropylation of CMC under alkaline conditions. The effects of key reaction parameters, including propylene oxide amount and reaction time, on the structure and resulting properties were systematically investigated. The resulting CMHPC were comprehensively characterized using FTIR, solid state ¹³C NMR, and scanning electron microscopy (SEM), etc., confirming the successful hydroxypropyl group incorporation and morphological changes. In our findings, the suitable concentrations for NaOH and CMC were 5% and 4%, respectively, which could balance the yield and solution fluidity. CMHPC exhibited a much faster dissolution speed (3–5 min) than that of CMC (>30 min), indicating markedly enhanced hydrophilicity and solubility. Moreover, CMHPC also exhibited improved salt and acidity tolerance due to the steric hindrance of hydroxypropyl groups. CMHPC was also used to modify recycled coarse aggregate (RCA), and the results indicated that CMHPC could enhance the surface compactness and structural integrity of RCA. Moreover, CMHPC effectively improved the water resistance of RCA by constructing a physical barrier and optimizing the pore structure of the aggregate. This research provides valuable insights into the fabrication of modified cellulose ethers in homogeneous systems and offers a practical pathway for producing high-value cellulose derivatives with tailored properties, particularly for potential construction applications. Full article

Deep fractured-porous carbonate reservoirs used for underground gas storage (UGS) experience simultaneous changes in temperature and effective stress during cyclic injection and withdrawal, so predicting permeability evolution is essential for evaluating long-term injectivity and deliverability. Using the Xiangguosi UGS as the engineering background, we measured steady-state gas permeability of three fractured-porous carbonate cores under representative conditions (20–80 °C; 15–35 MPa). Permeability decreases nonlinearly under coupled loading: changing temperature or effective stress alone typically reduces permeability by 30–70%, while the maximum reduction under concurrent increases in both variables exceeds 80% relative to the reference condition. An exponential model was fitted to quantify the decay parameter of permeability with effective stress (0.038–0.046 MPa⁻¹) and with temperature (0.016–0.020 °C⁻¹). In addition, the temperature-related exponential decay parameter decreases with increasing effective stress, because compliant fractures and larger pores are progressively pre-closed, weakening the permeability response to temperature. Finally, we propose a parsimonious separable exponential model that reproduces the measurements with a mean relative error below 12%, providing a practical constitutive relation for multiphysics simulations of UGS in fractured-porous carbonates. Full article

Ultrasonic-assisted laser-directed energy deposition (UA-DED) is a promising combined technology for manufacturing high-value thin-walled Inconel 718 components in aerospace. Nevertheless, the optimal ultrasonic frequency—a key parameter for achieving desirable performance in thin-walled Inconel 718 alloys—remains to be determined. In this study, we systematically investigated the influence of ultrasonic frequency (12–20 kHz) on the microstructure and mechanical properties of thin-walled Inconel 718 fabricated by UA-DED. The results revealed that an ultrasonic frequency of 20 kHz was optimal and can yield significant improvements in the microstructures of the as-deposited sample coordinate planes, manifested by the complete suppression of large pores, three-dimensional refinement of the γ matrix grains, alleviation of Nb and Mo segregation, the reduction of fragmented Laves particles, a decrease in residual macroscopic stresses, and homogeneous distributions of γ′/γ″ phases and γ-grain orientation. Meanwhile, the application of a 20 kHz ultrasonic frequency endows the manufactured thin-walled 718 parts with superior mechanical properties, including a tensile strength of 899 MPa in the laser scanning direction and 877 MPa in the build direction, along with the corresponding elongations of 34.8% and 38.9%. This work demonstrates the potential of modulating ultrasonic frequency to tailor microstructures and produce high-performance thin-walled Inconel 718 aerospace components. Full article

To address winter construction challenges such as slow early-stage strength development, inhibited hydration processes, and pore structure defects in concrete under low-temperature conditions, this study employs nano-TiO₂ as a modifying agent. It is incorporated into concrete through cement replacement methods; the study systematically investigates the influence of different admixture dosages (1%, 2%, 3%, by cement mass) on the mechanical properties, hydration process, and micro-pore structure of concrete. The test employed an electro-hydraulic servo universal testing machine to measure compressive and splitting tensile strengths. Differential thermal analysis (DTA) characterized the formation of hydration products (Ca(OH)₂). Micro-CT technology and pore network modeling were utilized to quantify micro-pore parameters. Results indicate that (1) nano-TiO₂ regulates the setting time of pure paste, with increased dosage shortening both initial and final setting times. At a 3% dosage, initial setting time plummeted from 5.5 min in the control group to 3.3 min; (2) nano-TiO₂ significantly enhances early-age (1–3 days) strength of low-temperature concrete, with optimal effect at 1% dosage. Compressive strength and splitting tensile strength at 1 day increased significantly by 20% and 26%, respectively, compared to the control group. Strength differences among groups gradually narrowed at 28 days; (3) DTA indicates that nano-TiO₂ accelerates early cement hydration; (4) micro-CT results show that the 1% dosage group exhibits significantly reduced porosity at day 1 compared to the control group, with notable decreases in Grade 0 and Grade 1 interconnected porosity resulting in the most optimal pore structure density. In summary, the optimal dosage of nano-TiO₂ in low-temperature environments is 1% by mass of cement. Through the synergistic “nucleation-filling effect,” it promotes early-stage hydration and optimizes pore structure, providing technical support for winter concrete construction. Full article

Ice accumulation on power transmission lines poses serious threats to operational safety and can lead to substantial social and economic impacts. While various anti-icing coatings have been investigated, their performance is often limited by the effectiveness and durability of anti-icing. Slippery lubricant-infused porous surfaces (SLIPSs) have shown remarkable anti-icing properties and durability, aided by their lubricant-infused and self-healing capability. In this study, SLIPSs were successfully fabricated on aluminum substrates using a two-step anodization process. The effects of the anodizing parameter of the current density on pore diameter and depth at each stage were systematically investigated. Compared to untreated aluminum and superhydrophobic coatings (SHCs), SLIPSs presented good anti-icing properties. First, at −6 °C, droplets slid off the surface completely within 4340.5 ms without pinning, indicating sustained droplet-shedding capability. It also significantly delayed ice formation, extending the freezing time to 80 min—eight times longer than that of the untreated surface. Moreover, the SLIPSs also exhibited ultra-low ice adhesion, with an initial strength of only 6.93 kPa. Meanwhile, after 100 frosting–defrosting cycles, SLIPSs could still maintain low ice adhesion strength (<20 kPa). The prepared SLIPS with a Y-shaped pore structure demonstrates good potential for anti-icing. Full article

This study investigated the effects of encapsulated capsaicinoids (CAPs), containing 0.47% capsaicin and 0.22% dihydrocapsaicin, on growth, serum parameters, nutrient digestibility, and intestinal health in weaned piglets. A total of 168 piglets were randomly assigned to four groups: a basal diet or the same diet supplemented with 200 (LDC), 400 (MDC), or 600 (HDC) mg/kg of CAPs. The results indicated that CAPs improved lipid metabolism, evidenced by higher crude fat digestibility in the LDC and MDC groups and reduced serum low-density lipoprotein cholesterol in all CAP groups compared to the control. Glutathione peroxidase activity was significantly higher in the MDC and HDC groups. Histological analysis showed reduced hepatic vacuolation, enlarged fungiform papillae with shallower taste pores in the tongue epithelium, and deeper ileal crypts in the LDC group. At the molecular level, ZO-1 expression in the ileum was significantly upregulated in LDC piglets. Colonic microbiota analysis revealed decreased relative abundances of Lachnospiraceae_AC2044_group, Lachnospiraceae_XPB1014_group, and Rikenellaceae_RC9_gut, while Butyricicoccus was significantly enriched in the LDC group. In conclusion, CAPs supplementation enhanced fat digestibility, lipid metabolism, antioxidant capacity, intestinal development, and colonic microbiota composition, with the 200 mg/kg dose showing the most pronounced effects. Full article

Droplet impact on porous mesh surfaces is a common phenomenon in fields such as thermal management systems, biomedical manufacturing, and precision agriculture. As a substrate with microstructures, the mesh surface allows liquid penetration upon droplet impact. The resulting loss of liquid mass significantly alters the impact dynamics of the residual droplet on the surface. This study experimentally compares the behavior of water droplets impacting superhydrophobic mesh surfaces with different pore sizes against that on smooth surfaces. It focuses on analyzing how liquid penetration affects parameters such as spreading time ($t_s$), maximum spreading factor (${\beta }_{max}$), contact time ($t_c$), and droplet height ($h$). The results show that the substantial liquid loss induced by large-pore meshes directly leads to a marked decrease in spreading time and maximum spreading factor. Furthermore, the “pancake bouncing” phenomenon observed on the superhydrophobic mesh surfaces significantly shortens the contact time, providing a new perspective for minimizing the contact duration between droplets and solid surfaces. By establishing the correlation between pore size and droplet impact behavior, this study provides key structural design guidelines for applications such as advanced printing systems and efficient pesticide spraying, thereby achieving the goal of proactively regulating liquid dynamics through surface microstructure. Full article

Rainfall-induced failures in red clay slopes are common, yet the coupled influence of soil structure degradation and rainfall temporal patterns on slope hydromechanical behavior remains poorly understood. This study advances the understanding by investigating a cut slope failure in Yunnan through integrated field monitoring, laboratory testing, and numerical modeling. Key advancements include: (1) elucidating the coupled effect of structure degradation on both shear strength reduction and hydraulic conductivity alteration; (2) systematically quantifying the impact of rainfall temporal patterns beyond total rainfall; and (3) providing a mechanistic explanation for the critical role of early-peak rainfall. Mechanical and hydrological parameters were obtained from intact and remolded samples, with soil-water retention estimated via pedotransfer functions. A hydro-mechanical finite element model of the slope was constructed and calibrated using recorded rainfall, displacement data and failure surface. Six simulation scenarios were designed by combining three strength conditions (intact at natural water content, intact at saturation, remolded at natural water content) with two hydraulic conductivity values (intact vs. remolded). Additionally, four synthetic rainfall patterns, including uniform, peak-increasing, peak-decaying and bell-shaped rainfall, were simulated to evaluate their influence on pore water pressure development and slope stability. Results show remolding reduced hydraulic conductivity 4.7-fold, slowing wetting front advance and increasing shallow pore water pressure. Intact soil facilitated deeper drainage, elevating pressure near the soil-rock interface. Strength reduction induced by structure degradation (water saturating and remolding) enlarged the slope deformation zone by 1.5 times under same hydraulic conductivity. Simulations using saturated intact strength best matched field observations. The results from this specific slope indicate that strength parameters primarily control stability, while permeability affects deformation depth. Simulations considering different rainfall patterns indicate that slope stability depends more critically on the temporal distribution of rainfall intensity than on the total amount. Overall, peak-decaying rainfall led to the most rapid rise in pore water pressure, earliest instability and lowest failure rainfall threshold, whereas peak-increasing rainfall showed the opposite trends. Our findings outline a practical framework for assessing red clay slope stability during rainfall. This framework recommends using saturated intact strength parameters in stability analysis. It highlights the important influence of rainfall temporal patterns, especially those with an early peak, on failure timing and rainfall threshold. Full article

This paper synthesizes lessons learned from drilling a CO₂-storage stratigraphic well in the San Juan Basin (New Mexico, USA) to clarify drivers of operational incidents and to inform future well planning. A literature review of regional drilling problems was combined with pre-drill engineering based on offset-well history and a geomechanical model, including casing, cementing, and hydraulics designs developed in commercial software; these designs were compared with field execution to extract incident-specific lessons. The most frequent problems observed are lost circulation, stuck pipe, and poor control of drilling parameters, consistent with complex lithology and reservoir pressure depletion that reduces fracture pressure below anticipated values. Based on the lessons learned, three mitigations are proposed as follows: (1) update the geomechanical model with the latest pore, fracture pressure estimates; (2) apply underbalanced drilling using nitrified mud by injecting nitrogen through a parasite string while drilling intermediate and production sections; and (3) maintain operating limits (weight on bit < 44.5 kN, top-drive rotation < 45 rpm, and pump rate < 1.32 m³/min) to improve fluid returns through low-fracture-pressure intervals. Simulation results support the applicability of the proposed solutions. Full article

The use of powder metallurgy in the manufacturing of automotive components requires understanding the influence of porosity on fatigue behaviour. The most widely accepted explanation for the impact of porosity on the fatigue limit is Murakami’s “√Area = √A” theory. However, the presence of elongated or irregular pores in sintered steels challenges this simplification. This study analyses the fatigue behaviour of three sintered steels and performs a statistical and geometrical assessment of porosity. Results demonstrate that replacing the √A parameter with the ellipse-fitted major axis (d_max) reduces the average prediction error from nearly 50% to below 6%, markedly improving the predictive accuracy of defect-based fatigue models. Full article

High regeneration energy demand remains a critical barrier to the large-scale deployment of ethanolamine-based (MEA-based) CO₂ capture. This study adopts an Al₂O₃ ceramic-membrane heat exchanger (CMHE) to recover both sensible and latent heat from the stripped gas. Experiments confirm that heat and mass transfer within the CMHE follow a coupled mechanism in which capillary condensation governs trans-membrane water transport, while heat conduction through the ceramic membrane dominates heat transfer, which accounts for more than 80%. Guided by this mechanism, systematic structural optimization was conducted. Alumina was identified as the optimal heat exchanger material due to its combined porosity, thermal conductivity, and corrosion resistance. Among the tested pore sizes, CMHE-4 produces the strongest capillary-condensation enhancement, yielding a heat recovery flux (q value) of up to 38.8 MJ/(m² h), which is 4.3% and 304% higher than those of the stainless steel heat exchanger and plastic heat exchanger, respectively. In addition, Length-dependent analyses reveal an inherent trade-off: shorter modules achieved higher q (e.g., 14–42% greater for 200-mm vs. 300-mm CMHE-4), whereas longer modules provide greater total recovered heat (Q). Scale-up experiments demonstrated pronounced non-linear performance amplification, with a 4 times area increase boosting q by only 1.26 times under constant pressure. The techno-economic assessment indicates a simple payback period of ~2.5 months and a significant reduction in net capture cost. Overall, this work establishes key design parameters, validates the governing transport mechanism, and provides a practical, economically grounded framework for implementing high-efficiency CMHEs in MEA-based CO₂ capture. Full article

This study investigates the relationship between apparent electrical resistivity (ER) and key material parameters governing moisture and pore-structure characteristics of concrete. An experimental program was conducted using six concrete mix designs, where ER was continuously measured under controlled wetting and drying cycles to characterize its dependence on the degree of saturation (DS). Results confirmed that ER decreases exponentially with increasing DS across all mixtures, with R² values between 0.896 and 0.997, establishing DS as the dominant factor affecting electrical conduction. To incorporate additional pore-structure parameters, eight input combinations consisting of DS, porosity (P), water–cement ratio (WCR), and compressive strength (f′c) were evaluated using five machine learning models. Gaussian Process Regression and Neural Networks achieved the highest accuracy, particularly when all parameters were included. SHAP analysis revealed that DS accounts for the majority of predictive influence, while porosity and WCR provide secondary but meaningful contributions to ER behavior. Guided by these insights, nonlinear multivariate regression models were formulated, with the exponential model yielding the strongest predictive capability (R² = 0.96). The integrated experimental–computational approach demonstrates that ER is governed by moisture dynamics and pore-structure refinement, offering a physically interpretable and statistically robust framework for nondestructive durability assessment of concrete. Full article