Search Results (30)

Fractures in straight-wall linings is a common disease that seriously affects the integrity and service life of tunnels. The presence of insufficient lining thickness can be regarded as one of the most important factors causing fractures. In this study, the fracture behaviors of straight-wall tunnels with insufficient lining thickness under progressive compressive loading were investigated. First, the fracture characteristics and failure mode were explored. Subsequently, the deformation behaviors were investigated by digital image correlation (DIC) technology. Finally, the fracture pattern was systematically discussed. The results show that the deformation intensifies in the areas with insufficient lining thickness, which is prone to induce cracks. As the ratio or range of insufficient thickness increases, the severity of fractures intensifies and the failure mode tends to be more complex. In addition, whether the lining comes into contact with the surrounding rock in the area with insufficient thickness has a significant impact on the failure mode. Furthermore, the more serious the defect is, the more obvious the spalling phenomenon will be. Moreover, the failure mode of straight-wall tunnels can basically be attributed to the combined effect of the fractures of defect zones, arch feet and tunnel floor. Full article

The presented research delivers a comprehensive evaluation of anticorrosive cathodic electrodeposition (CED) coatings through an integrated performance and process capability analysis—an approach that remains extremely limited in the literature, particularly in the context of statistically designed experiments (DoEs) applied to CED systems. This study therefore addresses a notable gap by focusing on the role of polymerization variables in determining coating quality through DoE to quantify the influence on coating thickness uniformity, adhesion integrity and impact resistance, while all other deposition parameters were rigorously controlled. Prior to coating application, all specimens were prepared and conditioned in accordance with ISO 1513:2010. Coating thickness was determined in compliance with ISO 2808:2019, adhesion was characterized by cross-cut methodology according to ISO 2409:2020 and dynamic mechanical resistance was evaluated using a falling-weight apparatus in accordance with ISO 6272-1:2011. The obtained datasets were subjected to statistical capability analysis within the PalstatCAQ environment, providing Cp, Cpk, Pp and Ppk indices in line with ISO 22514-7:2021 and IATF 16949:2016 requirements. Results evidenced non-linear dependencies of thickness formation on curing parameters, with potential capability indices (Cp > 1.8; Pp ≈ 1.4) indicating favorable process dispersion, while performance indices (Cpk < 0.5; Ppk < 0.4) revealed systematic mean shifts and deviations from normality confirmed by Shapiro–Wilk and Anderson–Darling tests. Adhesion testing demonstrated a direct correlation between curing conditions and interfacial bonding, reaching ISO Grade 0 classification. Complementary impact resistance assessments corroborated these findings, showing that insufficient curing induced extensive cracking and delamination. Furthermore, SEM–EDX analysis performed on Sample n.3 of X₂ variable confirmed the chemical integrity and multilayered structure of the CED coating. Full article

Thin steel plates with stiffeners are widely employed in several branches of engineering, combining mechanical strength with low weight and serving as both structural and cladding components. However, the influence of the side-wall inclination angle of hat-stiffeners on the stiffness distribution and deflection patterns of steel plates remains insufficiently explored. This study conducts computational modeling to evaluate the deflection of thin steel plates reinforced with hat-stiffeners. The plates were considered simply supported and subjected to a uniformly distributed load. The Constructal Design method and the exhaustive search technique were employed, allowing for geometric evaluation and optimization. A fraction corresponding to 30% of the plate volume was removed and redistributed to generate longitudinal hat-stiffener geometries by varying its side-wall angle and thickness. The smaller base of the hat-stiffeners was imposed as a geometric constraint and therefore kept fixed. The results indicate a nonlinear trend between the side-wall angle, the moment of inertia, and the resulting deflection, leading to a new geometrical pattern that connects the angular inclination to the overall stiffness behavior of the plate. Angles between 105° and 130° provided the best performance, reducing the maximum deflection by 93.72% compared with the reference plate and improving it by around 7.5% relative to previous studies. These findings illustrate how geometric configuration can enhance performance in line with Constructal Design principles. Full article

To address the issues of low permeability, clogging susceptibility, and insufficient circumferential bearing capacity of traditional drainage blind pipes behind tunnel linings in water-rich areas, this study proposes a novel curved-mesh circumferential drainage blind pipe specifically designed for such environments. First, through engineering surveys and comparative analysis, the limitations and application demands of conventional circumferential annular drainage blind pipes in highway tunnels were identified. Based on this, the key parameters of the new blind pipe—including material, wall thickness, and aperture size—were determined. Laboratory tests were then conducted to evaluate the performance of the newly developed pipe. Subsequently, the pipe was applied in a real-world tunnel project, where a construction process and an in-service blockage inspection method for circumferential drainage pipes were proposed. Field application results indicate that, compared to commonly used FH50 soft permeable pipes and F100 semi-split spring pipes, the novel curved-mesh drainage blind pipe exhibits superior circumferential load-bearing capacity, anti-clogging performance, and deformation resistance. The proposed structure provides a total permeable area exceeding 17,500 mm², three to four times larger than that of conventional drainage pipes, effectively meeting the drainage requirements behind tunnel linings in high-water-content zones. The use of four-way connectors enhanced integration with other drainage systems, and inspection of the internal conditions confirmed that the pipe remained free of clogging and deformation. Furthermore, the curved-mesh design offers better conformity with the primary support and demonstrates stronger adaptability to complex installation conditions. Full article

Laser-based powder bed fusion of metals (PBF-LB/M) is one of the most promising additive manufacturing technologies to fabricate complex-structured metal parts. However, its corresponding applications have been limited by technical bottlenecks and increasingly strict industrial requirements. Process optimization, a scientific issue, urgently needs to be solved. In this paper, a three-phase transient model based on the level-set method is established to examine the heat transfer and melt pool behavior in PBF-LB/M. Surface tension, the Marangoni effect, and recoil pressure are implemented in the model, and evaporation-induced mass and thermal loss are fully considered in the computing element. The results show that the surface roughness and density of metal parts induced by heat transfer and melt pool behavior are closely related to process parameters such as laser power, layer thickness, scanning speed, etc. When the volumetric energy density is low, the insufficient fusion of metal particles leads to pore defects. When the line energy density is high, the melt track is smooth with low porosity, resulting in the high density of the products. Additionally, the partial melting of powder particles at the beginning and end of the melting track usually contributes to pore formation. These findings provide valuable insights for improving the quality and reliability of metal additive manufacturing. Full article

The Tankou area is a vital production capacity replacement area in the Jianghan oilfield. The recovery of the amount of erosion in Qianjiang Formation and Jinghezhen Formation is significant for studying this area’s tectonic evolution and geothermal history. The target layer, characterised by well-developed plastic materials, intense tectonic deformation, and insufficient well data, fails to meet the applicability criteria of the conventional denudation estimation methods. This study proposes a novel approach based on the structural strain characteristics. The method estimates the stratigraphic denudation by analysing residual formation features and fault characteristics. First, a stress analysis is performed using the fault characteristics, and the change law for the thickness of the target layer is summarised based on the characteristics of the residual strata to recover the amount of erosion in the profile. Second, a grid of the stratigraphic lines in the profiles of the main line and the tie line is used to complete the recovery of the amount of erosion in the plane through interpolation, and the results of the profile recovery are corrected again. Finally, the evolution results of the geological equilibrium method and the stress–strain analysis are compared to analyse the reasonableness of their differences and verify the accuracy of the erosion recovery results. The area of erosion in each layer increases from bottom to top. The amount of denudation in each layer gradually increases from the denudation area near the southern slope to the surrounding area. It converges to 0 at the boundary of the denudation area. The maximum amount of erosion is distributed in the erosion area close to the side of the residual layer with a low dip angle. The specific denudation results are as follows: Qian1 Member + Jinghezhen Formation has a denudation area of 6.3 km² with a maximum denudation thickness of 551 m; Qian2 Member has a denudation area of 2.6 km² with a maximum denudation thickness of 164 m; Qian3 Member has a denudation area of 2.3 km² with a maximum denudation thickness of 215 m; Upper Qian4 Submember has a denudation area of 1.54 km² with a maximum denudation thickness of 191 m; and Lower Qian4 Submember has a denudation area of 1.2 km² with a maximum denudation thickness of 286 m. This method overcomes the conventional denudation restoration approaches’ reliance on well logging and geochemical parameters. Using only seismic interpretation results, it achieves relatively accurate denudation restoration in the study area, thereby providing reliable data for timely analyses of the tectonic evolution, sedimentary facies, and hydrocarbon distribution patterns. In particular, the fault displacement characteristics can be employed to promptly examine how reasonable the results on the amount of denudation between faults are during the denudation restoration process. Full article

This study considered the molding process of a thin-walled composite structure, imported from a CAD model, with the requirements of the uniformity of the mechanical properties and wall thickness. The developed numerical process model, which includes both the vacuum infusion and post-infusion stages, takes into account the entire complex of processes evolving in a spreading liquid resin, as well as in a porous preform. The controlled process parameters are the temperature and the magnitudes and times of pressure applied to the open surface of the preform and in the vacuum line. The low thickness of the preform walls and the fixation of its inner surface on an open composite mold allow the mechanical part of the problem to be simplified, thus considering only the preform deformation normal to the opened surface, which provides a significant reduction in the simulation time and the ability to effectively optimize the process. The examples associated with the three control modes considered here show that the presented model’s description of the process, with the toolkit for selecting the controlled parameters, eliminates critical situations such as the formation of dry spots, the premature blocking of the vacuum port, or the uneven distribution and insufficient amount of the reinforcing component in the preform. This is due to the appropriately described process dynamics up to the moment of a sharp increase in viscosity and the hardening of the resin. This approach additionally provides access to process parameters that would be inaccessible in a full-scale experiment. Full article

The research and related tests aimed to investigate the effect of different heat inputs on the microstructure and properties of the joint when using laser-backing welding for X80 steel, with the purpose of guiding a reasonable adjustment of heat inputs to obtain a sound and high-quality joint, and ultimately laying the foundation for the engineering application of laser-backing welding. The fiber-laser-backing welding is performed on a 22 mm thick X80 steel, before which a groove is prepared and assembled; joints were obtained under different heat inputs (162, 180, 210, 270 J/mm) with orthogonal combinations of laser power and welding speed. The microstructure and properties of the joints were characterized by using an optical microscope, scanning electron microscope, and microhardness tester. According to this investigation, the morphology of the joint is directly affected by the heat input, and insufficient heat input (<180 J/mm) will lead to an unacceptable weld profile. The width of the weld and heat-affected zone gets bigger as the heat input increases. The hardness nephograms of the joints under different heat inputs show that the weld has the highest hardness, followed by the coarse-grain heat-affected zone and the fine-grain heat-affected zone, sequentially. The less heat input, the lower the joint hardness; when the heat input increases to 270 J/mm, the coarse-grain zone near the fusion line shows obvious hardening. In addition, heat input also affects the impact toughness of the weld. The grain size of X80 steel with a lower content of niobium easily becomes coarse under excessive heat input (270 J/mm), resulting in the degradation of the grain-boundary slip ability; hence, the impact toughness of the joint deteriorates. The optimal heat input of 210 J/mm was identified, achieving a grain size of nearly 14 µm and providing a balanced combination of lower strength and higher impact toughness. Full article

Background and Objectives: Pediatric patients can acquire scars from both accidental injury and surgical procedures. While scars cannot be avoided if a full-thickness injury occurs, scar visibility may be minimized through a variety of approaches. In this narrative review, we evaluate the current evidence and propose an algorithm for scar management in pediatric patients. Materials and Methods: A review of the literature was performed for scar management techniques for pediatric patients. Management modalities based on the type of scar and dosing, treatment regimen, and safety profiles are described in this article and used to create a scar management algorithm. Results: The initial step to scar management in the pediatric population involves ensuring minimal wound tension, which can be achieved through making the incision along relaxed skin tension lines, and early, minimal tension wound closure. Subsequent treatments to optimize scar care should begin 2–3 weeks following wound closure and involve the application of silicone gel or sheets and scar massaging. When topical products are insufficient, laser therapy can be utilized for the management of immature erythematous or thick scars. When mature, pathological scars form such as atrophic scars, hyperpigmentation, hypertrophic scars, or keloids, a combination of modalities is recommended. These modalities vary by scar type and include retinoids and dermabrasion for atrophic scars; retinoids, hydroquinone, and laser therapy for hyperpigmentation; and pressure therapy, corticosteroids, and laser therapy for hypertrophic scars and keloids. When mature, pathological scars persist following 12 months of non-invasive therapies, surgical excision should be considered. Conclusions: Several treatment options are available to manage scars in the pediatric population depending on scar type. Full article

The present study focuses on analysis of the soil cover structure (SCS, SCSs), which is the most detailed level of soil organization in space. The detail in which complex SCS can be studied is often insufficient, since until now it has not been possible to map it over large areas at scales larger than 1:10,000. To increase the detail in which SCS can be studied, the methods of identifying the bare soil surface (BSS) and averaging its multitemporal spectral characteristics were used, which opens up new possibilities for mapping complex SCS over large areas. New SCSs of leached chernozems (Luvic Chernic Phaeozem) were discovered, which can produce patterns on satellite images similar to sections of Timan agate—agate-like soil cover structures (ASCS, ASCSs). ASCSs are formed on Quaternary sediments of varying thickness from 0.3 to 6 m, underlain by carbonate and red sediments of the Permian period. The ASCS pattern is formed by ring-shaped stripes (rings) of different colors and brightness, which are determined by the carbonate and red-colored inclusions involved in the arable horizon. Eight soil varieties were identified to describe ASCSs during the study. According to the WRB, there are six main soil types, and according to the classification of Russian soils in 1977, there are four types. ASCSs were identified over large areas and soil maps of ASCSs were constructed using multitemporal spectral characteristics of the BSS in the form of multitemporal soil line coefficients. Neural networks were used to identify BSS on big remote sensing data. ASCSs have contrasting soil properties and contrasting fertility (productivity of agricultural crops). ASCS maps can serve as the basis for task maps of precision farming systems. Perhaps ASCSs are unique objects for the area of chernozem distribution, where in one soil profile there are rocks with an age from the first thousand years (Quaternary) to 250 million years (Permian). Chernozems are fertile, studied, mercilessly exploited, but sometimes they are simply beautiful—agate-like. Full article

Ultrasonic welding of fibre-reinforced thermoplastics is a joining technology with high potential for short welding times and low energy consumption. While the majority of the current studies on continuous ultrasonic welding have so far focused on woven reinforcements, unidirectional materials are preferred for highly loaded aerospace components due to their better mechanical performance. Therefore, this paper investigates the influence and interdependence of the welding speed, amplitude, and energy director thickness on the weld quality of adherends made of unidirectional composites. The quality of the welded joints is assessed by a single-lap shear strength and fracture surface analysis complemented by the microscopic analysis of cross-sections and comparison to a co-consolidated reference. The results showed that the welding process is highly affected by changing welding speeds for a given amplitude. Furthermore, while lower amplitudes lead to significant scatter in the welding quality, higher amplitudes result in increased heating rates and a fully molten energy director even for high welding speeds. Nevertheless, insufficient consolidation at high welding speeds results in porosity in the weld line. Finally, it was observed that thicker, and therefore more compliant, energy directors lead to more uniform melting of the energy director and less deviation in the weld quality for a wider range of welding speeds. Full article

Voids behind tunnel linings can be formed either during or after the construction phase, occurring due to inadequate backfilling, substandard workmanship, water erosion, or gravitational forces. Investigations into numerous tunnels in which collapses occurred while in operation have indicated that voids behind the liner constitute the primary contributors to these failures. Consequently, it is imperative to devise lining reinforcement strategies tailored to the specific conditions encountered in the field. Fiber-reinforced plastic (FRP) represents a viable alternative construction material that has been widely utilized in the reinforcement of concrete structures. It is essential to quantitatively assess the reinforcing effect of FRP grids when they are employed in the restoration of deteriorated tunnel linings, thereby facilitating the development of effective maintenance designs. In this study, we aimed to enhance the sensitivity analysis of the reinforcement method by evaluating the impact of voids through the analysis of bending moments and axial forces within the tunnel lining. The effects of voids based on the different locations in which they occur were explored numerically through an Elastoplast finite element analysis. The study involved simulating tunnel linings that had been reinforced with FRP grids and assessing the effects of such reinforcement in tunnels afflicted with various structural problems. Based on the outcomes of these simulations, the internal forces within the lining are scrutinized, and the efficacy of the reinforcement is appraised. Full article

Background/Objectives: Diabetic macular edema (DME) is a significant cause of visual impairment, often treated with anti-vascular endothelial growth factor (anti-VEGF) agents. However, some patients do not respond adequately to this treatment. This study aims to evaluate the contribution of the intravitreal dexamethasone (DEX) implant as a second-line treatment in DME patients with insufficient response to anti-VEGF therapy or with high treatment burden. Methods: This retrospective multicenter cohort study was conducted across seven clinical sites in Switzerland. The study included eyes with active DME that had been pretreated with anti-VEGF for at least six months before receiving DEX therapy. Data were extracted from electronic patient records, focusing on best-corrected visual acuity (BCVA), central subfield thickness (CST), and injection frequency. Results: A total of 95 eyes from 89 patients (38.8% females, mean age 65.6 ± 9.1 years, follow-up time 80.6 ± 38.5 [13.5–166.7] months) were analyzed. Prior to the first DEX implant, eyes had undergone an average of 16.0 ± 13.3 anti-VEGF injections over 32.5 ± 22.4 months. Post-DEX treatment, 22.1% of eyes received DEX monotherapy, 44.2% received a combination of DEX and anti-VEGF, 25.3% continued with anti-VEGF monotherapy, and 8.4% received no further treatment. The number of anti-VEGF injections decreased significantly from 6.4 ± 3.1 in the year before DEX to 1.6 ± 2.4 in the year after DEX (p < 0.001). BCVA remained stable (0.4 ± 0.3 logMAR at baseline, 0.4 ± 0.5 logMAR at 24 months, p = 0.2), while CST improved from 477.7 ± 141.0 to 320.4 ± 125.5 μm (p < 0.001), and the presence of retinal fluid decreased from 98.0% to 61.1% (p = 0.021). During follow-up, 26.3% of eyes required glaucoma medication, 4.2% underwent glaucoma surgery, and 1.1% needed cataract surgery. Conclusions: In real-world clinical settings, the addition of DEX to anti-VEGF therapy in DME patients significantly reduces treatment burden and retinal fluid while maintaining visual function. Treatment decisions should balance anatomical and functional outcomes, considering individual patient needs. Full article

Landfills necessitate a liner barrier system to prevent the leakage of contaminants into the surrounding soil. However, the currently employed compacted clay liner (CCL) is insufficient to prevent the leakage of heavy metal ions. This study proposes a novel landfill liner system utilizing sludge-based activated carbon (SAC)-modified clay. The adsorption characteristics of SAC-modified clay liner (SAC-CCL) for Cd(II) or Cu(II) were evaluated through batch tests. The permeability coefficient and unconfined compressive strength of SAC-CCL were assessed through permeation and unconfined compression tests. The permeability coefficient of the SAC-modified clay ranged from 2.57 × 10⁻⁹ to 1.10 × 10⁻⁸ cm/s. The unconfined compressive strength of the SAC-CCL varied between 288 and 531 kPa. The migration of Cd(II) or Cu(II) within an 80 cm thick, full-scale SAC-CCL was simulated using soil column tests. The diffusion coefficient (D) was calculated by inversion using the one-dimensional solute migration equation. The diffusion coefficients (D) for Cd(II) and Cu(II) ranged from 1.9 × 10⁻¹⁰ to 13.5 × 10⁻¹⁰ m²/s. The retardant performance of SAC-CCL for Cd(II) and Cu(II) followed the order: 3% SAC-CCL > 1% SAC-CCL > CCL > 5% SAC-CCL, from strongest to weakest. Consequently, SAC-modified clay demonstrates significant potential as a landfill lining material. However, the migration behavior of heavy metal ions in SAC-CCLs under cyclic dry–wet conditions requires further investigation. Full article

There are more than 13,000 new cases of cervical cancer each year in the United States and approximately 245,000 survivors. External beam radiation and brachytherapy are the front-line treatment modalities, and 60% of patients develop vaginal damage and constriction, i.e., stenosis of the vaginal vault, greatly impeding sexual function. The incidence of vaginal stenosis (VS) following radiotherapy (RT) for anorectal cancer is 80%. VS causes serious quality of life (QoL) and psychological issues, and while standard treatment using self-administered plastic dilators is effective, acceptance and compliance are often insufficient. Based on published patient preferences, we have pursued the design of a soft inflatable dilator for treating radiotherapy-induced vaginal stenosis (VS). The critical component of the novel device is the dilator balloon wall material, which must be compliant yet able to exert therapeutic lateral force levels. We selected a commercially available silicone elastomer and characterized its stress–strain characteristics and hyperelastic properties. These parameters were quantified using uniaxial tensile testing and digital image correlation (DIC). Dilator inflation versus internal pressure was modeled and experimentally validated in order to characterize design parameters, particularly the dilator wall thickness. Our data suggest that an inflatable silicone elastomer-based vaginal dilator warrants further development in the context of a commercially available, well-tolerated, and effective device for the graded, controlled clinical management of radiotherapy-induced VS. Full article