Porosity Rate Research Articles

Evaluating the Impact of Wastewater Irrigation on Soil Health and Maize Productivity

The increasing scarcity of freshwater resources necessitates the exploration of alternative water sources for agricultural irrigation. This study evaluates the impact of different water sources canal water, tubewell water, sewerage water, and industrial wastewater on soil health and maize productivity. Conducted over two growing seasons, the experiment was laid out in a randomized complete block design with four replications at research area of Ayub Agriculturte Research Institute, Faisalabad. Key soil physical properties, including bulk density, porosity, and infiltration rate, were assessed pre- and post-irrigation. Concurrently, maize growth parameters such as germination rate, plant height, biomass, and grain yield were meticulously recorded. The results indicated that soil irrigated with sewerage and industrial wastewater exhibited significant increases in bulk density and reductions in porosity and infiltration rates compared to canal and tubewell water. Despite these alterations in soil physical properties, maize irrigated with sewerage water showed a comparable growth pattern to that irrigated with canal and tubewell water, with no significant differences in germination rate or plant height. However, grain yield and biomass were significantly higher in plots irrigated with canal water, followed closely by tubewell water, sewerage water, and lastly, industrial wastewater. Industrial wastewater irrigation notably decreased soil health and maize productivity due to the presence of heavy metals and other pollutants. In contrast, sewerage water, while still inferior to canal and tubewell water, provided a viable alternative, maintaining acceptable soil health and maize yield levels. This study underscores the potential of using treated wastewater for irrigation in regions facing water scarcity, highlighting the need for stringent quality monitoring and treatment protocols to mitigate adverse effects on soil health and crop productivity.

Zinc-doped hydroxyapatite loaded chitosan gelatin nanocomposite scaffolds as a promising platform for bone regeneration.

The advancement in the arena of bone tissue engineering persuades us to develop novel nanocomposite scaffolds in order to improve antibacterial, osteogenic, and angiogenic properties that show resemblance to natural bone extracellular matrix. Here, we focused on the development of novel zinc-doped hydroxyapatite (ZnHAP) nanoparticles (1, 2 and 3 wt%; size: 50-60 nm) incorporated chitosan-gelatin nanocomposite scaffold, with an interconnected porous structure. The addition of ZnHAP nanoparticles decreases the pore size (~30 µm) of the chitosan gelatin scaffold. It was observed that with the increase in the concentration of ZnHAP nanoparticles (3 wt%) in CG scaffolds, the swelling ratio (1374%), porosity (68%) and degradation rate (35%) decreased, whereas mechanical property (1 MPa) increased. The deposition of apatite crystals due to the incorporation of ZnHAP nanoparticles on CG scaffolds revealed the excellent osteoconductive potential of the nanocomposite scaffolds. MC3T3-E1 osteoblastic cells seeded with CG-ZnHAP nanocomposite scaffolds depicted better cell adhesion, proliferation and differentiation to osteogenic lineages. Finally, the CAM assay revealed better angiogenesis supporting vascularisation. Overall, the results showed that the CG-ZnHAP3 nanocomposite scaffold could be a potential candidate for bone defect repair.&#xD.

Optimizing foam concrete performance using mixed foaming method: impact of mixing speed, mixing duration, and foam dosage

Foamed concrete has gained significant attention, especially in the field of thermal insulation and acoustic insulation. However, all production methods are based on the pre-foaming method, while the mixed foaming method is an infrequent approach that should be considered and could be challenging. For this reason, this paper attempt to highlight this method and valuate it on par with the pre-foaming method in the production of foamed concrete, both in terms of structure and performance. These performances are directly dependent on the pore structure of this material (pore size, porosity rate, and pore distribution). Therefore, a process has been developed for sample preparation to achieve a final product with a well-controlled size and distribution of porosity, meeting the desired performance criteria. This process involves varying the following parameters: mixing speed (from 400 to 1000 rpm), mixing time (from 2 to 12 minutes), and the dosage of foaming agent (from 0.05 to 0.2%). The effect of mixing speed, mixing duration and the dosage of the foaming agent on the generated foam rate, density, structure at the millimeter scale, structure at the micrometer scale, and thermal conductivity was demonstrated. The obtained results show that with a generated foam rate extending to 79%, a density reaching 428 kg/m³, and a thermal conductivity achieving 0.181 w/k.m, the mixed foaming method becomes an important and competitive approach to the pre-foaming method in the production of foamed concrete.

Effect of curing process on the structure and properties of paper-based friction materials

As one of the three main components of paper-based friction materials, resin plays a crucial role in determining the material’s performance. Resin behavior varies under different curing conditions, affecting its properties and the overall performance of the material. To find the optimal curing process for paper-based friction materials, we studied the curing process and mechanism of polyamide-modified phenolic resin (PA–PF composite resin) and examined how the curing process influences the structure and properties of these materials. The findings indicate that paper-based friction materials cured at 160°C for 60 minutes show the highest fiber/resin interface bonding strength, with a tensile strength of 14.4 MPa, shear strength of 1.3 MPa, and a strength retention rate of 99.2% after reaching a stable permanent deformation rate. These materials also demonstrate stable dynamic mechanical thermal performance, including a storage modulus of 2758.6 MPa, a cross-linking density of 146343 mol/m³, and a glass transition temperature of 205.7°C. Furthermore, they have excellent compression resilience, with a low permanent deformation rate of 4.1%, and show a uniform pore distribution with a porosity rate of 57.1%. The wear rate is measured at 0.3 × 10−8 cm³/N · m, and the average dynamic friction coefficients are 0.3, 0.1, and 0.1 at pressures of 0.5 MPa, 1.9 MPa, and 3.0 MPa, respectively, with dynamic/static friction coefficient ratios of 0.9, 0.9, and 0.8.

State Fragility and the Resurgence of Military Coups in West-Africa

State fragility and coups in Franco-phone West Africa constitute a worrisome political issue caused by weak leadership, instability, poverty, corruption, weak governance institutions, insurgency and terrorism, kidnapping and banditry, border porosity and high rates of military coup. The paper analysed the causes and consequences of military takeovers in West Africa and the role of regional organizations in curbing them. Secondary materials were used for data analysis. The paper concludes that the brazen-faced and audacious French imperialism in West Africa has contributed to the ongoing instability and insecurity in the subregion; creating a fertile ground for coup resurgence, which was driven by military leaders seeking to gain control and exploit the resources of the region for their own benefit. The paper thus suggests that as soon as the polity is stabilized, political power should be returned to the people in the affected States.

State Fragility and the Resurgence of Military Coups in West-Africa

State fragility and coups in Franco-phone West Africa constitute a worrisome political issue caused by weak leadership, instability, poverty, corruption, weak governance institutions, insurgency and terrorism, kidnapping and banditry, border porosity and high rates of military coup. The paper analysed the causes and consequences of military takeovers in West Africa and the role of regional organizations in curbing them. Secondary materials were used for data analysis. The paper concludes that the brazen-faced and audacious French imperialism in West Africa has contributed to the ongoing instability and insecurity in the subregion; creating a fertile ground for coup resurgence, which was driven by military leaders seeking to gain control and exploit the resources of the region for their own benefit. The paper thus suggests that as soon as the polity is stabilized, political power should be returned to the people in the affected States.

Utilization of Silica from Palm Ash Waste as an Abrasive Material in Brake Friction Composite

The silica element in palm ash has the potential to be an alternative source of silica material to replace mineral silica, making it more environmentally friendly and reducing production costs. This research aims to utilize silica from palm ash waste as an abrasive material in brake friction composites. The silica from palm ash was isolated by a leaching process using 1 M HCl solution at a temperature of 70 °C for 90 minutes. Isolated silica was then characterized by X-ray fluorescence (XRF). The composition of silica was varied by volume fraction (0, 2, 4, and 6%). The mixing process of the powder mixture was conducted using a chopper mixer for 5 minutes, The powder mixture is then hot compressed using uniaxial hot pressing at a pressure of 47 MPa and a temperature of 165 °C for 15 minutes. Post-curing of the samples was carried out at a temperature of 165 °C for 10 hours. The samples were characterized by density, porosity, hardness R-scale, friction coefficient, and specific wear rate. The research results showed that the palm ash was successfully purified with a silica content of 27.3% to 57.2%. Increasing volume fraction of palm ash silica decreases in density and hardness, while porosity increases. The sample with 4% volume of palm ash silica exhibited better friction performance and a lower specific wear rate. Palm ash silica has the potential to replace the silica mineral for brake friction composites.

Impact of Scrap Impurities on AlSi7Cu0.5Mg Alloy Flowability Using Established Testing Methods

In view of the increasing demand for secondary aluminum, which is intended to partially replace the very energy- and resource-intensive primary aluminum production, effective treatment methods can maintain the high quality level of light metal castings. The transition from a linear to a circular economy can result in an accumulation of oxides or carbides in aluminum. Therefore, melt purification is crucial, especially as foundries aim to increase the use of often dirty end-of-life scrap. Nonmetallic inclusions in the melt can impact its flowability and mechanical properties. As the purity of the melt increases, its flow length also tends to increase. Available assessment methods like reduced pressure test or K-mold are capable of ensuring high levels of purity. This study demonstrates the implication of inclusions originating from dirty scrap. An experimental test run deals with various scrap contents in an AlSi7Cu0.5Mg alloy and shows correlations between impurity and performance, expressed by flowability and mechanical properties. These performance indicators have been connected to inclusion and porosity rates. In conclusion, these findings emphasize the need for further extensive research on contaminants in the field of scrap melting and the development of methods for easy-to-handle assessment methods.

Water vapor condensation in porous media: Effects of fracture, porosity, and flow rate revealed by rapid 4D neutron imaging

Water vapor condensation in porous media: Effects of fracture, porosity, and flow rate revealed by rapid 4D neutron imaging

Identification of Groundwater Table Depth as A Source of Raw Water in Elelim District, Yalimo Regency

Clean water is a fundamental need for communities, sourced from both surface water (e.g., rivers, streams, springs) and groundwater (surface and deep aquifers). Groundwater dynamics are influenced by natural factors, including geology and geomorphology, which determine aquifer characteristics such as type, depth, thickness, and permeability. Geological structures influence groundwater flow direction, while lithology affects aquifer ion concentration and water quality. Surface morphology impacts groundwater table depth and movement patterns, with morphogenesis influencing permeability, porosity, and infiltration rates. This research investigates groundwater potential in Yalimo Regency, Mountainous Papua Province. The research aims to evaluate aquifer characteristics using regional geological and geomorphological assessments complemented by advanced mapping technology. The methodology integrates field mapping with geospatial analysis to identify and delineate groundwater resources. Results provide a detailed understanding of aquifer distribution, capacity, and potential for sustainable utilization. Conclusions emphasize the importance of combining traditional and technological approaches for accurate groundwater resource assessment, offering insights for effective water management in the region.

Investigation of Silver- and Plant Extract-Infused Polymer Systems: Antioxidant Properties and Kinetic Release.

This study evaluated the impact of silver particles, suspended in Arnica montana flower extract, on the physicochemical characteristics and release dynamics of antioxidant compounds in PVP (polyvinylpyrrolidone)-based hydrogel systems. The hydrogels were synthesized via photopolymerization with fixed amounts of crosslinker (PEGDA) and photoinitiator, while the concentration of the silver-infused extract was systematically varied. Key properties, including the density, porosity, surface roughness, swelling capacity, and water vapor transmission rate (WVTR), were quantitatively analyzed. The results demonstrated that increasing the silver content reduced the hydrogel density from 0.6669 g/cm3 to 0.2963 g/cm3 and increased the porosity from 4% to 11.04%. The surface roughness parameters (Ra) rose from 8.42 µm to 16.33 µm, while the WVTR increased significantly from 65.169 g/m2·h to 93.772 g/m2·h. These structural changes directly influenced the release kinetics of antioxidant compounds, with kinetic modeling revealing silver-dependent variations in the evaluated release mechanisms. This innovative approach of integrating silver particles and plant-derived antioxidants into hydrogels highlights a novel pathway for tailoring material properties. The observed enhanced porosity and moisture regulation underscore the hydrogels' potential for biomedical applications, particularly in wound care, where controlled moisture and antioxidant delivery are critical. These findings provide new insights into how silver particles modulate hydrogel structures and functionalities.

A comparative study of thermal sprayed Al2O3-TiO2 coatings on PM AISI 316L

The widespread use of stainless steels (SS) in various applications is hindered by their inadequate wear resistance, hardness and high density. Structural metallic components fabricated via powder metallurgy (PM) exhibit lower densities compared to those produced by conventional methods due to their inherent high porosity. However, this compromises their mechanical and corrosion performance. This study has investigated the application of pure Al2O3 and Al2O3 + 13 %TiO2 powders with varying particle sizes on PM AISI 316L substrates to enhance their mechanical and wear properties. The phase composition, microhardness, coating morphology, surface roughness, porosity and wear rate of coated and uncoated samples were comparatively analysed to elucidate the influence of both TiO2 addition and coating powder particle size on the mechanical properties and surface morphology of the samples. Microstructural and XRD studies confirmed good mechanical and metallurgical bonding of the coatings to the substrate. All of the coated samples exhibited 24 to 34 times higher surface roughness and 1.3 to 2.1 times lower porosity values compared to the substrate. The finer sized TiO2 added alumina-based coating powder reduced the surface roughness and porosity value to 1.8 and 1.4 times respectively while the use of the coarser sized one reduced these values to 1.3 and 1.2 times respectively compared to the pure Al2O3 coated surface. 8-times higher hardness and 70-times lower wear rate values compared to the substrate were the most significant improvements observed in the pure Al2O3 coated surface among all coated samples. Although TiO2 addition to the coating powder decreased hardness by 1.1 times and increased wear rate by 1.8 times, spraying finer TiO2 added coating powders resulted in a slight improvement in both hardness and wear resistance compared to the coarser one.

Micromorphology evolution and properties of strontium-zinc-phosphate chemical conversion coatings on Ti:Effect of Zn2+ and Ca2+ in the reaction solution

Bioactive strontium zinc phosphate (SrZn2(PO4)2, SZP) coatings have attracted much attention in the surface modification of medical metal materials. And the micro-morphologies of that coating have an important influence on cellular function and osseointegration. This study prepared a variety of micro-morphology SrZn2(PO4)2 coatings on titanium (Ti) using the phosphate chemical conversion (PCC) method. The effect of Zn2+ concentration in the reaction solution on the micro-morphology and properties of the SZP coatings was studied. The results showed that the SZP crystal size increased with increasing concentration of Zn2+ in the reaction solution, which also led to a more regular morphology of the coatings on Ti. A corresponding increase in the thickness, hydrophilicity, and roughness of the SZP coatings was also observed because of the increase in Zn2+ concentration. The bond strength of the coatings showed an initial increase followed by a slight decline with rising Zn2+ concentration. Moreover, the addition of Ca2+ in the reaction solution also significantly affected the micro-morphology of the SZP coatings, changing the crystal morphology from rectangular blocky to shuttle-shaped lamellar. The wettability, bonding strength, porosity, and ion release rate of the coatings were also increased because of the addition of Ca2+. This study elucidated the mechanism of Zn2+ and Ca2+ ions in the reaction solution on the morphology and properties of SZP coatings. The findings provided a novel approach to controlling and optimizing the micro-morphology of phosphate coatings to enhance their osteogenic activity.

Overcoming deep-dewatering challenges in food waste digestate with polyethylene oxide as an innovative conditioning agent

The effective treatment of food waste digestate is critical for reducing environmental pollution and mitigating carbon emissions, with deep dewatering playing a pivotal role. Conventional dewatering agents such as polyaluminum chloride (PAC) and polyacrylamide (PAM), commonly employed in municipal sludge treatment, exhibit limited efficacy when applied to food waste digestate due to the latter's high salinity and advanced fermentation stages. This study introduces polyethylene oxide (PEO) as a novel conditioning agent and investigates its dewatering performance in comparison to PAC and PAM, elucidating the underlying mechanism. PEO conditioning markedly improves deep-dewatering, reducing digestate moisture content from 93.11 % to 56.71 % and lowering specific resistance to filtration (SRF) by 90.3 %. In contrast, PAM, PAC, and their combination achieve moisture reductions to 81.18 %, 84.49 %, and 87.07 %, respectively, with significantly lower SRF improvements. PEO promotes the release of bound water by weakening solid-liquid binding energy, facilitating the transition of bound water to free water and enhancing overall water mobility. Moreover, compressibility coefficient analyses and X-ray computed tomography (X-CT) reveal that PEO treatment significantly increases filter cake porosity, with an effective porosity rate of 56.65 %, resulting in superior drainage performance. The enhanced dewatering efficiency of PEO stems from its ability to improve water permeability within the filter cake during compression, distinguishing its mechanism from traditional flocculation (PAM) and coagulation (PAC) approaches. This work highlights the potential of PEO as a highly effective solution for food waste digestate treatment in solid waste management, with its salt-resistant properties further extending its applicability to high-salinity waste streams.

Evaluating flue gas geo-sequestration and EOR in fractured reservoirs through simulated synergistic reservoir characteristics and injection kinetics

The global reliance on hydrocarbon resources and fossil fuels has resulted in a significant surge in carbon dioxide emissions, necessitating urgent measures to mitigate greenhouse gas emissions. Integrating CO2 storage with enhanced oil recovery (EOR) presents a promising solution for reducing emissions and enhancing oil recovery by sequestering CO2 within oil reservoirs, especially in fractured carbonate reservoirs. The research utilized the Eclipse simulator to model different gas injection scenarios in a crude oil reservoir, focusing on assessing the effectiveness of CO2 and flue gas geo-sequestration and EOR, performing sensitivity analyses on reservoir characteristics, and evaluating the impact of varying injection rates on gas storage capacity and oil recovery factor. The findings demonstrated a superior capacity to store flue gas (150 MMSCF) in comparison to CO2 (85 MMSCF) and flue gas injection demonstrated better reservoir pressure maintenance than CO2 injection, while CO2 injection resulted in a higher oil recovery factor of 52% compared to flue gas injection at 36%. Additionally, analysis of reservoir characteristics in gas storage revealed that, an augmentation in reservoir porosity, permeability, and injection rate substantiated an increase in gas storage capacity for both CO2 and flue gas injection. Except for CO2 storage, which displayed a normal distribution trend in the permeability analysis. Additionally, it was elucidated that higher reservoir pressure and temperature in flue gas injection resulted in a reduction of gas storage capacity, while these variables exhibited relative stability in the context of CO2 injection. The scrutiny of gas storage in reservoir characteristics unveiled substantial alterations in porosity and injection rate, signifying their pivotal roles in influencing gas storage capacity. In the EOR study, heightened reservoir pressure, temperature, permeability, and injection rate collectively contributed to an amplified oil recovery for both flue gas and CO2, except CO2 injection demonstrated a normal distribution trend in oil recovery within the permeability analysis. Conversely, higher porosity was associated with a decrease in oil recovery. The findings of this research provide valuable insights into the feasibility and effectiveness of employing flue gas geo-sequestration and EOR in fractured carbonate reservoirs.

Committee machine learning: A breakthrough in the precise prediction of CO2 storage mass and oil production volumes in unconventional reservoirs

Accurate prediction of CO2 storage mass and cumulative oil production is critical in the context of combining subsurface carbon capture with enhanced oil recovery (CCS-EOR). This study introduces a novel committee machine-learning Gaussian Process Regression (CML-GPR) model, which integrates three well-established machine-learning algorithms—Random Forest (RF), Multi-Layer Extreme Learning Machine (MELM), and Generalized Regression Neural Network (GRNN). The combination of these models leverages the strengths of each algorithm: RF captures nonlinear relationships, MELM enhances computational efficiency, and GRNN provides smooth, generalized predictions. By integrating these complementary techniques, the CML-GPR model demonstrates significant improvements in predictive accuracy over individual models, addressing limitations in their performance. The model predicts CO2 storage mass and cumulative oil production based on nine key reservoir input variables, including depth, porosity, and CO2 injection rate, among others. Utilizing a large dataset of 21,193 data points from reservoir simulations, a Mahalanobis distance-based outlier detection method further refines the input data quality. The CML-GPR model achieves root mean square error (RMSE) values of 0.49 million metric tons for CO2 storage mass and 13.68 million barrels for cumulative oil production, significantly outperforming individual models. The CML-GPR model provides a robust tool for optimizing CO2 storage capacity and oil recovery, with practical implications for real-world reservoir management, ensuring more efficient and reliable CCS-EOR operations. This study represents a pioneering advancement in predictive modeling, offering valuable insights for optimizing both CO2 storage and enhanced oil recovery in complex reservoirs.

Stable manufacturing of electrospun PVDF/FPU multiscale nanofiber membranes and application of high efficiency protective mask filter elements

Effective particulate matter (PM) filtration in air has become a significant focus of scientific research due to the increased focus on environmental health and sustainable development. In this work, efficient nanofiber scale preparation technology is realized, based on our self-developed electrospinning equipment. Polyvinylidene fluoride/fluorinated polyurethane (PVDF/FPU) nanofiber composite membrane with multi-scale structure was designed and prepared, and successfully applied in the field of air filtration. PVDF/FPU ultrafine nanofibers with a diameter of 30 ± 5 nm were produced by employing high-conductivity dilute solution electrospinning. Subsequently, a PVDF/FPU composite nanofiber membrane material with a double-layer multiscale structure was constructed by adjusting the proportion and sequence of the spinning units of different scales. The results indicate that this double-layer, multiscale PVDF/FPU composite nanofiber membrane features a minute average pore size (0.36 μm), a high porosity rate (94.56 %), and outstanding hydrophobic properties (with a contact angle of 138.6°). This demonstrated exceptional filtration efficiency (99.98 %) and low filtration resistance (67 Pa) under test conditions of 32 L/min. After 10 wash cycles, the filtration efficiency remained above 99 %, indicating remarkable stability. Furthermore, the COMSOL simulation software was utilized to analyze the gradient filtration mechanism of the nanofiber membrane, which correlated well with the experimental results. The double-layer multiscale PVDF/FPU nanofiber composite membranes developed during this study offers a novel approach for creating highly efficient, low-resistance air-filtration materials.

Physicochemical Characterization and Kinetics Study of Polymer Carriers with Vitamin C for Controlled Release Applications.

This study focuses on the selection and evaluation of a kinetic model for the release of vitamin C from different delivery systems, including microcapsules, hydrogels, and a hybrid system combining both. The microcapsules were synthesized from a 2% sodium alginate solution and with vitamin C incorporated in selected formulations. Hydrogels were obtained through photopolymerization using poly(ethylene glycol) diacrylate and polyvinyl alcohol, with and without the addition of vitamin C. The hybrid system incorporated the vitamin C-containing microcapsules within the hydrogel matrix. Physicochemical properties, such as density, porosity, and water vapor transmission rate (WVTR), were evaluated. Kinetic studies of vitamin C release were conducted under dynamic and static conditions, and the experimental data were fitted to six different kinetic models: zero-order, first-order, second-order, Higuchi, Korsmeyer-Peppas, and Hixson-Crowell. The Higuchi and Korsmeyer-Peppas models provided the best fit for most systems, indicating that the release is predominantly controlled by diffusion and, in dynamic conditions, swelling of the matrix. The hybrid system, while exhibiting slower release than the microcapsules and hydrogel alone, demonstrated more controlled and sustained release, which is advantageous for applications requiring prolonged action.

Low-temperature sinterability of graphene-Cu nanoparticles:Molecular dynamics simulations and experimental verification

As three-dimensional integration technology evolves, the integration density and operating speed of circuits continue to increase, raising the demands for interconnect reliability. It is urgent to explore novel interconnect materials to meet reliability requirements. Given its excellent mechanical, physical, and electrical properties, graphene-nanocopper has emerged as a promising new interconnect material. However, graphene’s low affinity with copper requires an exploration of its sintering mechanism to guide the sintering process. In this study, we initially utilized molecular dynamics calculations to compare the sintering processes of Cu NPs and G@Cu NPs. Graphene limits the sintering progress of G@Cu NPs, with shear strengths of Cu NPs (8.38 MPa) < G@Cu NPs (12.78 MPa) < benzimidazole@Cu NPs (13.28 MPa), and porosity rates of Cu NPs (38.19 %) > G@Cu NPs (14.28 %) > benzimidazole@Cu NPs (10.36 %). Post-sintering service reliability verifies that graphene limits the sintering process of G@Cu NPs. The sintering process of graphene with copper was subsequently simulated for different core–shell diameters, within a specific range, revealing that increasing the copper core diameter and graphene shell thickness decreases the sintering progression. However, the increase in graphene may concurrently alter defects, thus accelerating the sintering process. Finally, simulations conducted at sintering temperatures of 473 K, 573 K, and 673 K for G@Cu NPs show that increasing the temperature accelerates the sintering process, reducing the porosity rate from 19.48 % to 12.64 % and increasing the shear strength from 10.14 MPa to 13.92 MPa. It was verified that the temperature increase promoted the G@Cu sintering process. Our research reveals atomistic changes in G@Cu NPs under low-temperature conditions and provides a deeper understanding of low-temperature sintering for G@Cu NPs.

Terahertz Non-Destructive Testing of Porosity in Multi-Layer Thermal Barrier Coatings Based on Small-Sample Data

Accurately characterizing the internal porosity rate of thermal barrier coatings (TBCs) was essential for prolonging their service life. This work concentrated on atmospheric plasma spray (APS)-prepared TBCs and proposed the utilization of terahertz non-destructive detection technology to evaluate their internal porosity rate. The internal porosity rates were ascertained through a metallographic analysis and scanning electron microscopy (SEM), followed by the reconstruction of the TBC model using a four-parameter method. Terahertz time-domain simulation data corresponding to various porosity rates were generated employing the time-domain finite difference method. In simulating actual test signals, white noise with a signal-to-noise ratio of 10 dB was introduced, and various wavelet transforms were utilized for denoising purposes. The effectiveness of different signal processing techniques in mitigating noise was compared to extract key features associated with porosity. To address dimensionality challenges and further enhance model performance, kernel principal component analysis (kPCA) was employed for data processing. To tackle issues related to limited sample sizes, this work proposed to use the Siamese neural network (SNN) and generative adversarial network (GAN) algorithms to solve this challenge in order to improve the generalization ability and detection accuracy of the model. The efficacy of the constructed model was assessed using multiple evaluation metrics; the results indicate that the novel hybrid WT-kPCA-GAN model achieves a prediction accuracy exceeding 0.9 while demonstrating lower error rates and superior predictive performance overall. Ultimately, this work presented an innovative, convenient, non-destructive online approach that was safe and highly precise for measuring the porosity rate of TBCs, particularly in scenarios involving small sample sizes facilitating assessments regarding their service life.