Search Results (2,739)

To compare them with PTFE-40# steel tribo-pairs, the tribological properties of textured PEEK-40# (AISI 1040) steel friction pairs were researched under full-film lubrication conditions by manufacturing micro-dimples with different dimensions on the contact surfaces of 1040 steel discs using laser surface texturing (LST). After repeated tribological tests, the coefficients of friction (COFs), wear losses, and wear morphologies of the PEEK-1040 steel friction pairs were measured and analyzed. The results show that micro-dimples do not significantly reduce the average COFs of PEEK-1040 steel friction pairs when lubricated with a sufficient amount of hydraulic oil, but they do reduce the wear losses of most groups. When the dimple diameter was 250 μm, the dimple depth was 5 μm, the area ratio was 6.6%, and the mass loss of the 1040 steel disc was reduced by 90% compared to the smooth reference. In comparison to the behavior of the PTFE-1040 steel tribo-pairs, PEEK-1040 steel friction pairs can provide better tribological performance, whether smooth or dimple-textured. This study offers important insights for the design of seals in machinery. Full article

The permeability of ionic rare is a crucial factor influencing the leaching rate of rare earth elements. In the Gannan region, many ionic rare earth ores exhibit poor permeability and high compressibility compared to sandy soils. The permeability coefficient is a key indicator of the hydraulic performance of these ores. Thus, this study investigates the permeability coefficients of ionic rare earth ores with varying fines contents during the leaching process, with a specific focus on analyzing the impact of fines on permeability performance. To provide a comprehensive assessment of the influence of fines, we prepared ionic rare earth ore samples with fines contents of 5%, 10%, 15%, 20%, 25%, and 30%, ensuring that the overall particle size distributions remained consistent with the original gradation. A constant head permeability test was employed to measure the permeability coefficients of these ore samples throughout the leaching process. We specifically examined how varying fines contents influenced permeability across the upper, middle, and lower layers of the ore body, as well as the overall permeability when subjected to both distilled water and magnesium sulfate solutions. To further elucidate the differences in permeability performance among the various rare earth ore samples, we performed a data fitting analysis of the initial permeability coefficients against fines content, uniformity coefficient, average particle diameter, and void ratio. This analysis aims to quantify the fines effect across different rare earth ores and establish correlations among state parameters, such as fines content, and the initial permeability coefficient. Full article

Hydraulic technology has been instrumental in the extensive application of offshore mechanical equipment, particularly in drilling platforms and ships, where high-performance hydraulic fluids are essential for safe and efficient operations. Addressing the urgent need for water-based hydraulic fluids as an alternative to traditional oil-based fluids, this study introduces a novel water-based hydraulic fluid fortified with phytic acid, derived from plant seeds, to achieve low biotoxicity, low coefficient of friction, and reduced frictional heat generation. The integration of phytic acid has significantly enhanced the lubricating performance, reducing the average coefficient of friction to as low as 0.013, as tested by the four-ball tester, which is the lowest value reported to date. Real-time monitoring of the temperature rise of the friction testing apparatus using an infrared thermal imager revealed a 78.6% reduction in temperature increase. Acute toxicity assays using Brine Shrimp demonstrated that the 96 h LC50 value for the water–glycol flame-resistant hydraulic fluid with added phytic acid exceeded 26,304 mg/L, indicating low toxicity. Characterization analyses elucidated the mechanisms underlying the improved tribological properties, highlighting the potential of this eco-friendly fluid for safe and efficient offshore operations. Full article

The technical training associated with urban water cycle management has a markedly multidisciplinary character. In Spain, training in this field to cover the different professional profiles involved in urban water management ranges from specific intermediate and higher Vocational Education and Training Programmes to related subjects included in various university degrees, as well as specialised master’s degrees in a very specific discipline involved in water management. Paradoxically, the companies in the sector are finding it difficult to find intermediate and higher technicians with training in line with their current needs to meet the challenges they must face in order to manage the sewerage and supply networks as efficiently as possible. It is necessary to incorporate, in Vocational Education centres, innovative methods and means that facilitate the acquisition of the skills required by key sectors for sustainability, such as urban water management. The incorporation of resources that help students to understand complex concepts in this field through the operation of pilot-scale equipment and installations that simulate those they will encounter in their professional performance can be of great value in facilitating the acquisition of the desired competences. In this work, a bibliographical review of the use of pilot plants for teaching purposes, in relation to technical aspects involved in the field of urban water management circumscribed to urban supply and sanitation networks, is carried out in order to assess the degree of their implementation as a training resource, which aspects are most frequently addressed, and the contribution they make to the improvement of teaching–learning processes. Full article

This study investigates the potential of Chirich (Asphodelus aestivus) tuber, one of Turkey’s natural resources, for sustainable bio-hybrid film production. Bio-hybrid films developed from Chirich tuber starch in composite form with polyvinyl alcohol (PVOH) were thoroughly examined for their physical, mechanical, and barrier properties. During the production process, twin-screw extrusion and hydraulic hot pressing methods were employed; the films’ optical, chemical, and barrier performances were analyzed through FT-IR spectroscopy, water vapor permeability, solubility, and mechanical tests. To evaluate the films’ durability against environmental factors and model their properties, advanced computational model algorithms such as Gradient Boosting Regression (GBR), Random Forest Regression (RFR), and AdaBoost Regression (ABR) were utilized. The results showed that the GBR algorithm achieved the highest accuracy with 99.92% R² and presented the most robust model in terms of sensitivity to environmental factors. The results indicate that Chirich tuber-based bio-hybrid films exhibit significantly enhanced mechanical strength and barrier performance compared to conventional corn starch-based biodegradable polymers. These superior properties make them particularly suitable for industrial applications such as food packaging and medical materials, where durability, moisture resistance, and gas barrier characteristics are critical. Moreover, their biodegradability and potential for integration into circular economy frameworks underscore their environmental sustainability, offering a viable alternative to petroleum-derived plastics. The incorporation of ML-driven optimization not only facilitates precise property prediction but also enhances the scalability of bio-hybrid film production. By introducing an innovative, data-driven approach to sustainable material design, this study contributes to the advancement of bio-based polymers in industrial applications, supporting global efforts to mitigate plastic waste and promote environmentally responsible manufacturing practices. Full article

This study explores biohydrogen production through dark fermentation, an alternative supporting sustainable hydrogen generation. Dark fermentation uses organic waste under anaerobic conditions to produce hydrogen in the absence of light. Key process parameters affecting hydrogen yield, including substrate type, microorganism selection, and fermentation conditions, were examined. Various substrates, such as organic wastes and carbohydrates, were tested, and the role of anaerobic and facultative anaerobic microorganisms in optimizing the process was analyzed. The research also focused on factors such as pH, temperature, and hydraulic retention time to enhance yields and scalability. Additionally, the study modelled the process using ASPEN Plus software 14. This simulation identifies the bottle necks of this process. Due to the lack of available data, modelling and simulation of the described processes in ASPEN Plus required certain approximations. The simulation provides insight into the key challenges that need to be addressed for hydrogen production. Future research should indeed explore current limitations, such as substrate efficiency, process scalability, and cost-effectiveness, as well as potential advancements like the genetic engineering of microbial strains and improved bioreactor designs. Full article

In the harvesting operation, the stubble height of the grain is a vital parameter index in the combined harvesting operation; if the stubble is too high or too low, it will directly affect the harvesting quality and the service life of the header. At present, the profiling control system can only control the lift of the header in the vertical direction but not the horizontal direction and the angle of the cutter profiling. This study proposes a contouring control strategy and system for grain harvesting by analyzing the designed contouring adjustment mechanism and simulating the control method and hydraulic system through Amesim2404 software to simulate and analyze the control method and hydraulic system. Finally, different forward speeds of the harvester (5, 7, 9, and 11 km/h) and other cutting heights of the harvester were analyzed based on static and field tests and different stubble heights (100, 150, 200, and 250 mm) on the test indexes. The results of the field test showed that for different operating speeds, the error between the mean value of stubble height and the target value was small, the absolute error was less than 2 mm, the mean value of the coefficient of variation of stubble height was 4.53%, and the mean value of control accuracy is 94%. The developed adaptive control system of the profiled grain header has high precision and stability, which can provide a reference for the all-terrain profiling control technology of the combined harvester header deck. Full article

This study developed a semi-passive treatment system for manganese (Mn)- and zinc (Zn)-containing mine water by repurposing a neutralization tank into a biologically active stirred reactor. Laboratory-scale experiments demonstrated efficient removal of Mn²⁺ (>97%) and Zn²⁺ (>80%) with hydraulic retention times (HRTs) as short as 6 h—significantly faster than traditional passive systems. XRD and XANES analyses identified the predominant formation of birnessite, a layered Mn oxide, during Mn²⁺ oxidation, with Zn co-treatment promoting the precipitation of Zn-containing carbonates. Despite decreasing crystallinity of birnessite over time, microbial activity, dominated by Mn-oxidizing genera, such as Sphingomonas, Pseudonocardia, Sphingopyxis, Nitrospira, and Rhodobacter, persisted in the presence of Zn²⁺, ensuring system stability. Importantly, the low leachability of Mn and Zn from the resulting sludge in TCLP tests confirmed its environmental safety and potential for reuse. By leveraging existing infrastructure and microbial biomineralization, this system bridges the gap between passive and active treatments, significantly reducing treatment footprints and operational costs. These findings highlight the potential of repurposing mine water treatment tanks as a scalable, cost-effective solution for sustainable mine water remediation. Full article

This article presents the results of laboratory tests of compaction parameters and shear strength of silty soils with and without the addition of hydraulic binder in the form of lime and/or cement. The tests were carried out on samples formed with an optimum moisture content and with 0, 3, 5, and 8% hydraulic binder added to the dry mass of the soil. The soil samples were examined after 7 and 14 days of air–water treatment without and with freeze–thaw cycles. It was found that the addition of lime and cement caused changes in the compaction parameters. This effect depended to a large extent on the type of binder, and also on the grain size composition of the tested soil. The tests showed that the shear strength and the parameters describing it, i.e., the angle of internal friction and cohesion, were high and largely depended on the type of binder and the sample treatment method, as well as its duration. The obtained results indicate that the use of hydraulic binders was an effective method of surface stabilization. Improving soil properties based on the addition of a hydraulic binder is a beneficial method for the environment from the viewpoint of sustainable development and reducing CO₂ emissions because it does not require the use of, e.g., soil replacement. Using the SHAP algorithm, it was found that normal stress, initial moisture content, and curing time of the samples were the main input features that influenced the shear strength. Full article

Geoenvironmental engineered barriers, such as geotechnical and hydraulic layered structures called liners, are essential for protecting the environment from pollution. Liners are usually compacted clay liners (CCL), geomembranes (GM), geosynthetic clay liners (GCL), or a combination of these liners (composite liners), which require significant attention concerning materials, techniques, and procedures to perform adequately. This work reviews the function of geotechnical and hydraulic barriers as liners and highlights the lack of investigation and problematic aspects of them. In addition, the work provides an overview of the literature around earthworks which are liners’ specific configurations, such as landfills, dams, ponds, wastewater lagoons, and vertical barriers. Furthermore, the main investigations, issues, and perspectives are demonstrated, and are discussed alongside the trending research areas and sustainable new materials. This work highlights different directives in several countries for liner construction standards and testing program specifications, analyzing their economic aspects. The main studies on the subject have been compiled, and a bibliometric analysis was performed. Thus, this paper concludes by pointing out gaps in the research regarding alternative materials and structures within geoenvironmental investigations on liners, and signposts future scientific threads related to sustainable development. Full article

Lime-based mortars, frequently used in historic structures, are classified as hydraulic and non-hydraulic according to how they gain strength. In the past, various methods were used to improve the strength and durability properties of lime-based hydraulic mortars such as Khorasan mortar. Today, in studies carried out to increase the strength of lime-based mortars, the effects of binders, aggregates, and additives, which are the basic components of the mortar, are examined. In this study, the mechanical properties of Khorasan mortar mixtures, which are frequently used in the restoration of historical structures, were examined under the influence of different parameters. In particular, the effects of variables such as aggregate type and ratio (river sand and crushed brick), binder type and ratio (natural hydraulic lime, metakaolin, and blast furnace slag), and water/total dry material ratio on the strength of mortars were investigated experimentally. In the experimental study, two different aggregate types (river sand and crushed brick) were used in 1/3 and 1/2 ratios, and three different binders (natural hydraulic lime, metakaolin, and blast furnace slag) were used in different ratios. The water-to-total-dry-material ratios were set at 0.2 and 0.25. Standard test samples were then created from the prepared mortar mixtures, and their flexural and compressive strengths were assessed at 28 and 56 days. A statistical analysis of the experimental data was conducted using the Taguchi method, allowing for a detailed examination of how the different parameters influenced the strength of the mortars. Through this analysis, the optimal mixture ratios that maximized mortar strength were successfully identified. Full article

Fracturing is an indispensable technique in geothermal energy development. Large-sized model tests of different fracturing methods are crucial for evaluating the fracturing effect and extrapolating the results to field applications. For common hydraulic and deflagration fracturing methods, 40 × 40 × 40 cm³ granite samples were used to carry out fracturing tests under high-temperature conditions in this paper. Through the analysis of the fracturing parameters and multiscale fracture morphology, a series of key findings were summarized. Deflagration fracturing is more intense, notably unaffected by the principal stress difference, and is capable of generating fracture spaces tens of times larger than those created by hydraulic fracturing. Furthermore, high temperatures tend to produce more fracture zones rather than continuous cracks during hydraulic fracturing. In contrast, deflagration fracturing yields simpler and more regular fractures in granite at high temperatures. Finally, the influence of the borehole number and the quantity of the deflagration agent on the fracturing effect are briefly discussed. These findings provide valuable insights for enhancing reservoir stimulation in geothermal systems. Full article

The scanning curve of the soil–water characteristic curve (SWCC) represents the intermediate paths followed by soil as it transitions between the initial drying and main wetting cycles. The alternating occurrence of climatic conditions, such as rainfall and evaporation in different regions globally, provides a valuable framework for understanding how these dynamics influence the scanning curve. Monitoring the scanning curve can provide valuable insights for managing water resources and mitigating the impacts of drought, contributing to environmental sustainability by enabling more precise agricultural practices, promoting water conservation, and supporting the resilience of ecosystems in the face of climate change. It enhances sustainability by enabling data-driven designs that minimize resource use, reduce environmental impact, and increase the resilience of slopes to natural hazards like landslides and flooding. Available studies to determine the scanning curve of SWCC are limited and mostly conducted in the laboratory. This study aims to determine the real-time measurement of the scanning curve of SWCC for unsaturated soil. The research focuses on assessing the hysteresis behavior of residual soil slope from old alluvium through a combination of field instrumentation and laboratory testing. The pore size distribution was derived from the initial drying and main wetting SWCC. Field monitoring (scanning curve) indicates measurable deviations from the experimental results, including a 10% lower saturated water content and a 25% lower air-entry value. This study demonstrates the potential for field-based determination of scanning curves. It highlights their role in improving the prediction of the hydraulic behavior of residual slopes during varying climatic conditions. Full article

Bridges positioned near riverbeds experience complex interactions between flow dynamics and structural geometry, significantly affecting hydrodynamic loading and stability. This study analyzes the effect of deck proximity to the bed on pressure distribution and hydrodynamic loading, including drag and lift forces. Experimental tests were conducted in a rectangular channel using a scaled bridge deck model, varying deck positions, flow conditions, and upstream–downstream water depth levels. To the best of the authors’ knowledge, for the first time, a comparative analysis of hydrodynamic loads on bridge decks was conducted using both rigid and deformable granular beds. Pressure distributions on the front, rear, and bottom faces of the deck were measured using transducers sensors. Our findings corroborate that changes in Reynolds number have minimal impact on the deck drag and lift coefficients, under identical submergence conditions, whereas both coefficients decrease with the Froude number for both bed types. More importantly, the analysis of experimental evidence unveiled some interesting aspects pertaining to the physics of the phenomenon, allowing us to provide the following, unprecedented results: (1) lift and drag coefficients significantly decrease with proximity, exhibiting much higher values than those reported in the literature for larger clearance; (2) under identical hydraulic conditions (both upstream and downstream of the deck), drag and lift coefficients are significantly amplified by the presence of rigid beds compared to granular beds; and (3) the scour evolution alters the effective deck proximity, resulting in time-dependent hydrodynamic loads acting on the deck. Full article

Historically, a large fraction of fatigue testing of both components and structures has been performed using hydraulic actuators. These are typically driven by servo-valves, which are in themselves very inefficient. But, as most tests involve elastically stressing mechanical components, a lot of stored energy could be recovered. Unfortunately, servo-valves are not regenerative—simply metering out fluid in order to relax the system prior to the start of the next cycle. There is much to be gained with a more intelligently controlled system. The FastBlade facility in Scotland uses a new type of regenerative test hydraulics. Digital displacement pump/motors (DDPMs), originated by Artemis Intelligent Power, now Danfoss Scotland, are used to load and unload the test structure directly via hydraulic rams. The DDPMs are driven by induction motors supplied by three-phase frequency converters, each with a very loose speed correction target, such that they can speed up or slow down according to the instantaneous torque exerted by the load. The rotating assembly of the induction motor and DDPM is designed to have sufficient inertia so as to function as a kinetic energy storage flywheel. The loading energy is then cyclically transferred between the rotating inertia of the motor/DDPM and the spring energy in the test structure. The electric motor provides sufficient energy to maintain the target average cyclical shaft speed of the DDPM whilst the bulk of the system energy oscillates between the two storage mechanisms. Initial tests (at low load) suggest that this technique requires only 30% of the energy previously needed. FastBlade is a unique facility built by the University of Edinburgh and Babcock, with support from the UK EPSRC, conceived as a means of testing and certifying turbine blades for marine current turbines. However, this approach can be used in any cyclical application where elastic energy is stored. Full article