Search Results (7,063)

The construction industry plays a major role in the consumption of natural resources and the generation of waste. Construction and demolition waste (CDW) is produced in substantial volumes globally and is widely available. Its accumulation poses serious challenges related to storage and disposal, highlighting the need for effective strategies to mitigate the associated environmental impacts of the sector. This investigation intends to evaluate the influence of mixed CDW on the physical, mechanical, and durability properties of mortars with CDW partially replacing Portland cement, and allow performance comparisons with mortars produced with fly ash, a commonly used supplementary binder in cement-based materials. Thus, three mortar formulations were developed (reference mortar, mortar with 25% CDW, and mortars with 25% fly ash) and several characterization tests were carried out on the CDW powder and the developed mortars. The work’s principal findings revealed that through mechanical grinding processes, it was possible to obtain a CDW powder suitable for cement replacement and with good indicators of pozzolanic activity. The physical properties of the mortars revealed a decrease of about 10% in water absorption by immersion, which resulted in improved performance regarding durability, especially with regard to the lower carbonation depth (−1.1 mm), and a decrease of 51% in the chloride diffusion coefficient, even compared to mortars incorporating fly ash. However, the mechanical performance of the mortars incorporating CDW was reduced (25% in terms of flexural strength and 58% in terms of compressive strength), but their practical applicability was never compromised and their mechanical performance proved to be superior to that of mortars incorporating fly ash. Full article

During the process of oil and gas drilling, due to the existence of pores or micro-cracks, drilling fluid is prone to invade the formation. Under the action of hydration expansion of clay in the formation and liquid pressure, wellbore instability occurs. In order to reduce the wellbore instability caused by drilling fluid intrusion into the formation, this study proposed a method of forming a dynamic hydrogen bond cross-linked network weak gel structure with modified nano-silica and P(AM-AAC). The plugging performance of the drilling fluid and the performance of inhibiting the hydration of shale were evaluated through various experimental methods. The results show that the gel composite system (GCS) effectively optimizes the plugging performance of drilling fluid. The 1% GCS can reduce the linear expansion rate of cuttings to 14.8% and increase the recovery rate of cuttings to 96.7%, and its hydration inhibition effect is better than that of KCl and polyamines. The dynamic cross-linked network structure can significantly increase the viscosity of drilling fluid. Meanwhile, by taking advantage of the liquid-phase viscosity effect and the physical blocking effect, the loss of drilling fluid can be significantly reduced. Mechanism studies conducted using zeta potential measurement, SEM analysis, contact angle measurement and capillary force assessment have shown that modified nano-silica stabilizes the wellbore by physically blocking the nano-pores of shale and changing the wettability of the shale surface from hydrophilic to hydrophobic when the contact angle exceeds 60°, thereby reducing capillary force and surface free energy. Meanwhile, the dynamic cross-linked network can reduce the seepage of free water into the formation, thereby significantly lowering the fluid loss of the drilling fluid. This research provides new insights into improving the stability of the wellbore in drilling fluids. Full article

While acetic acid has proven effective as a mild acidic treatment for removing adhered mortar from recycled concrete aggregate (RCA) surfaces, its potential for dissolving damage to the surface of the original natural coarse aggregate (NCA) within the RCA and its impact on the resultant concrete properties require careful consideration. This investigation systematically evaluates the effects of varying concentrations of dilute acetic acid solutions, commonly used in RCA treatment protocols, through a multi-methodological approach that includes comprehensive physical characterization, stylus and 3D optical profilometry, scanning electron microscopy (SEM), and nanoindentation analysis. The results show that even dilute acid solutions have an upper concentration limit, as excessive acid concentration, specifically 0.4 M, induces significant textural dislocations on NCA surfaces, creating millimeter-scale erosion pits that increase aggregate water absorption by 18.5%. These morphological changes significantly impair concrete workability and reduce compressive strength performance. Furthermore, microstructural analysis reveals a 45.24% expansion in interfacial transition zone (ITZ) thickness, accompanied by notable reductions in elastic modulus and microhardness characteristics. In practical RCA treatment applications, for RCA containing limestone-based NCA, it is recommended to use acetic acid concentrations between 0.1 and 0.3 M to avoid substantial physical and microstructural degradation of aggregates and concrete. Full article

Agriculture is one of the most important sectors of the global economy, but it increasingly faces sustainability challenges in meeting rising food demands. The intensive use of mineral fertilizers not only improves yields, but also causes negative environmental impacts such as increasing greenhouse gas emissions, water eutrophication, and soil degradation. To develop more sustainable solutions, the focus is on organic fertilizers, which are produced using waste and biostimulants such as amino acids. The aim of this study was to develop and characterize liquid nitrogen–calcium–magnesium fertilizers produced by decomposing dolomite with nitric acid followed by further processing and to enrich them with a powdered amino acid concentrate Naturamin-WSP and liquid extracts from digestate, a by-product of biogas production. Nutrient-rich extracts were obtained using water and potassium hydroxide solutions, with the latter proving more effective by yielding a higher organic carbon content (4495 ± 0.52 mg/L) and humic substances, which can improve soil structure. The produced fertilizers demonstrated favourable physical properties, including appropriate viscosity and density, as well as low crystallization temperatures (eutectic points from –3 to –34 °C), which are essential for storage and application in cold climates. These properties were achieved by adjusting the content of nitrogenous compounds and bioactive extracts. The results of the study show that liquid fertilizers enriched with organic matter can be an effective and more environmentally friendly alternative to mineral fertilizers, contributing to the development of the circular economy and sustainable agriculture. Full article

With the development of wave energy, a promising renewable resource, oscillating water column (OWC) devices, has been extensively studied for its potential in harnessing this energy. However, traditional OWC devices face challenges such as corrosion and damage from prolonged exposure to harsh marine environments, limiting their long-term viability and efficiency. To address these limitations, this paper proposes a novel U-tube type dual chamber OWC wave energy conversion device integrated within a marine vehicle. The research involves the design of a U-tube dual-chamber OWC device, which utilizes the pitch motion of a marine vehicle to drive the oscillation of water columns within the U-tube, generating reciprocating airflow that drives an air turbine. Numerical simulations using computational fluid dynamics (CFD) were conducted to analyze the effects of various structural dimensions, including device length, width, air chamber height, U-tube channel width, and bottom channel height, on the aerodynamic power output. The simulations considered real sea conditions, focusing on low-frequency waves prevalent in China’s sea areas. Simulation results reveal that increasing the device’s length and width substantially boosts aerodynamic power, while air chamber height and U-tube channel width have minor effects. These findings provide valuable insights into the optimal design of U-tube dual-chamber OWC devices for efficient wave energy conversion, laying the foundation for future physical prototype development and experimental validation. Full article

This paper presents a novel multi-sensor system for enhanced maneuver analysis in Olympic dinghy sailing. In the ILCA class, there is an increasing demand for precise in-field measurement and analysis of physical properties beyond well-established velocity and course metrics. The low-cost setup presented in this study consists of a combination of commercially available sensor systems, such as the AdMos sensor for IMU and GNSS measurement, in combination with custom measurement systems for rudder and mast rotations using fully waterproofed potentiometers. Data streams are synchronized using GNSS time stamping for streamlined analysis. The resulting analysis presents a selection of 12 upwind tacks, with corresponding path overlays, detailed timeseries data, and performance metrics. The system has demonstrated the value of extended data analysis of in situ data with an elite ILCA 7 sailor. The addition of rudder and mast rotations has enabled enhanced analysis of on-water maneuvers for single-handed Olympic dinghies like the ILCA 7, on a level of detail previously reserved for simulated environments. Full article

This work presents a high-fidelity simulation of the Peach Bottom turbine trip (PBTT) benchmark using the Virtual Environment for Reactor Applications (VERA), a multiphysics reactor modeling tool developed by the U.S. Department of Energy’s Consortium for Advanced Simulation of Light Water Reactors energy innovation hub. The PBTT benchmark, based on a 1977 transient event at the end of cycle 2 in a General Electric Type-4 boiling water reactor (BWR), is a critical test case for validating core physics models with thermal feedback during rapid reactivity events. VERA was employed to perform end-to-end, pin-resolved simulations from conditions at the beginning of cycle 1 through the turbine-trip transient, incorporating detailed neutron transport, fuel depletion, and subchannel thermal hydraulics. The simulation reproduced key benchmark observables with high accuracy: the peak power excursion occurred at 0.75 s, matching the scram time and closely aligning with the benchmark average of 0.742 s; the simulated maximum power spike was approximately 7600 MW, which is within 3% of the benchmark average of 7400 MW; and void-collapse dynamics were consistent with benchmark expectations. Reactivity predictions during cycles 1 and 2 remained within 1500 pcm and 400 pcm of criticality, respectively. These results confirm VERA’s ability to model complex coupled neutronic and thermal hydraulic behavior in a BWR turbine-trip transient, which will support its use in future studies of modeling dryout, fuel performance, and uncertainty quantification for transients of this type. Full article

The efficiency of electric motors is highly dependent on their operating temperature, with lower temperatures contributing to enhanced performance, reliability, and extended service life. This study presents a comprehensive review of state-of-the-art cooling technologies and evaluates their impact on the thermal behavior of a commercial motor–generator system in high-demand applications. A baseline model of a permanent magnet synchronous motor (PMSM) was developed using MotorCAD 2023^® software, which was supported by reverse engineering techniques to accurately replicate the motor’s physical and thermal characteristics. Subsequently, multiple cooling strategies were simulated under consistent operating conditions to assess their effectiveness. These strategies include conventional axial water jackets as well as advanced oil-based methods such as shaft cooling and direct oil spray to the windings. The integration of these systems in hybrid configurations was also explored to maximize thermal efficiency. Simulation results reveal that hybrid cooling significantly reduces the temperature of critical components such as stator windings and permanent magnets. This reduction in thermal stress improves current efficiency, power output, and torque capacity, enabling reliable motor operation across a broader range of speeds and under sustained high-load conditions. The findings highlight the effectiveness of hybrid cooling systems in optimizing both thermal management and operational performance of electric machines. Full article

This study presents a hybrid approach to hydrological forecasting by integrating the physically based Soil and Water Assessment Tool (SWAT) model with Prophet time-series modeling and machine learning–based multi-output regression. Applied to the Cahaba watershed, the objective is to predict key environmental variables (precipitation, evapotranspiration (ET), potential evapotranspiration (PET), and snowmelt) and their influence on hydrological responses (surface runoff, groundwater flow, soil water, sediment yield, and water yield) under present (2010–2022) and future (2030–2042) climate scenarios. Using SWAT outputs for calibration, the integrated SWAT-Prophet-ML model predicted ET and PET with RMSE values between 10 and 20 mm. Performance was lower for high-variability events such as precipitation (RMSE = 30–50 mm). Under current climate conditions, R² values of 0.75 (water yield) and 0.70 (surface runoff) were achieved. Groundwater and sediment yields were underpredicted, particularly during peak years. The model’s limitations relate to its dependence on historical trends and its limited representation of physical processes, which constrain its performance under future climate scenarios. Suggested improvements include scenario-based training and integration of physical constraints. The approach offers a scalable, data-driven method for enhancing monthly water balance prediction and supports applications in watershed planning. Full article

Phosphogypsum, a byproduct of orthophosphoric acid production, is one of the large-tonnage wastes. Since phosphogypsum mainly consists of CaSO₄ 2H₂O, it can be considered as an alternative gypsum-bearing raw material in the production of gypsum binders. However, its features, such as particle morphology and the presence of impurities, can negatively affect the characteristics of phosphogypsum-based binders. Identification of these factors will allow us to develop methods for their minimization and increasing the efficiency of phosphogypsum use from the required source as a raw material for the production of phosphogypsum-based binders. In this regard, the manuscript contains a comprehensive and comparative analysis of phosphogypsum and natural gypsum, which makes it possible to establish their differences in chemical composition and structural and morphological features, which subsequently affect the properties of the phosphogypsum-based binder. It has been established that the key factor negatively affecting the strength of phosphogypsum-based paste (2.58 MPa) is its high water demand (0.89), which is due to the high values of the specific surface area of the particles and the presence of a large number of conglomerates with significant porosity in phosphogypsum. It has been suggested that preliminary grinding of phosphogypsum can help reduce the amount of water required to obtain fresh phosphogypsum-based paste with a standard consistency and improve its physical and mechanical properties. Full article

(1) Background: Physical inactivity is a major public health concern in modern society. Group fitness programs are widely used to promote physical activity, combining choreographed movements with various dance steps and music. This study aimed to examine the effects of Zumba and MoFit group fitness programs on body composition parameters in women. (2) Methods: The study included 98 female participants (Mean age = 27.8 ± 2.9 years), divided into three groups: E1 (n = 33), which followed the experimental Zumba program; E2 (n = 31), which followed the experimental MoFit program; and a control group (n = 34), which continued with their usual daily activities for 10 weeks. Body composition was assessed using 14 variables measured with the InBody 270 analyser. Statistical analyses included paired t-tests, MANCOVA, and ANCOVA. (3) Results: The findings confirmed the positive effects of both group fitness programs on most body composition parameters in women (p < 0.001). However, Bonferroni post hoc test results indicated that the Zumba program led to significantly greater improvements in most body composition variables compared to the MoFit program. (4) Conclusions: Both Zumba and MoFit programs were effective in reducing body fat, increasing muscle mass, total body water, and mineral content, whereas the control group did not achieve positive changes. Full article

Deep coalbed methane (CBM) reservoirs are characterized by high hydrocarbon content and are considered an important strategic resource. Due to their inherently low permeability and porosity, horizontal well drilling is commonly employed to enhance production, with the length of the horizontal section playing a critical role in determining CBM output. However, during extended horizontal drilling, wellbore instability frequently occurs as a result of drilling fluid invasion into the coal formation, posing significant safety challenges. This instability is primarily caused by the physical intrusion of drilling fluids and their interactions with the coal seam, which alter the mechanical integrity of the formation. To address these challenges, interpenetrating and semi-interpenetrating network (IPN/s-IPN) hydrogels have gained attention due to their superior physicochemical properties. This material offers enhanced sealing and support performance across fracture widths ranging from micrometers to millimeters, making it especially suited for plugging applications in deep CBM reservoirs. A self-degradable interpenetrating double-network hydrogel particle plugging agent (SSG) was developed in this study, using polyacrylamide (PAM) as the primary network and an ionic polymer as the secondary network. The SSG demonstrated excellent thermal stability, remaining intact for at least 40 h in simulated formation water at 120 °C with a degradation rate as high as 90.8%, thereby minimizing potential damage to the reservoir. After thermal aging at 120 °C, the SSG maintained strong plugging performance and favorable viscoelastic properties. A drilling fluid containing 2% SSG achieved an invasion depth of only 2.85 cm in an 80–100 mesh sand bed. The linear viscoelastic region (LVR) ranged from 0.1% to 0.98%, and the elastic modulus reached 2100 Pa, indicating robust mechanical support and deformation resistance. Full article

Monitoring sediment concentration in water bodies is crucial for assessing water quality, ecosystems, and environmental health. However, physical sampling and sensor-based approaches are labor-intensive and unsuitable for large-scale, continuous monitoring. This study employs machine learning models to estimate suspended sediment concentration using images captured in natural light, named RGB, and near-infrared (NIR) conditions. A controlled dataset of approximately 1300 images with SSC values ranging from 1000 mg/L to 150,000 mg/L was developed, incorporating temperature, time of image capture, and solar irradiance as additional features. Random forest regression and gradient boosting regression were trained on mean RGB values, red reflectance, time of captured, and temperature for natural light images, achieving up to 72.96% accuracy within a 30% relative error. In contrast, NIR images leveraged gray-level co-occurrence matrix texture features and temperature, reaching 83.08% accuracy. Comparative analysis showed that ensemble models outperformed deep learning models like Convolutional Neural Networks and Multi-Layer Perceptrons, which struggled with high-dimensional feature extraction. These findings suggest that using machine learning models and RGB and NIR imagery offers a scalable, non-invasive, and cost-effective way of sediment monitoring in support of water quality assessment and environmental management. Full article

Background/Objectives: In recent years, the discharge of antibiotics into rivers and irrigation canals has increased. However, few studies have addressed the impact of these compounds on agricultural fields that use such water to meet crop demands. Methods: In this study, the transport of two types of gentamicin (pure gentamicin and gentamicin sulfate) was modeled at concentrations of 150 and 300 μL/L, respectively, in a soil with more than 60 years of agricultural use. Infiltration tests under constant head conditions and gentamicin transport experiments were conducted in acrylic columns measuring 14 cm in length and 12.7 cm in diameter. The scaling parameters for the Richards equation were obtained from experimental data, while those for the advection–dispersion equation were estimated using inverse methods through a nonlinear optimization algorithm. In addition, a fractal-based model for saturated hydraulic conductivity was employed. Results: It was found that the dispersivity of gentamicin sulfate is 3.1 times higher than that of pure gentamicin. Based on the estimated parameters, two simulation scenarios were conducted: continuous application of gentamicin and soil flushing after antibiotic discharge. The results show that the transport velocity of gentamicin sulfate in the soil may have short-term consequences for the emergence of resistant microorganisms due to the destination of wastewater containing antibiotic residues. Conclusions: Finally, further research is needed to evaluate the impact of antibiotics on soil physical properties, as well as their effects on irrigated crops, animals that consume such water, and the soil microbiota. Full article

Kefiran, the extracellular polysaccharide produced from the Generally Recognized as Safe (GRAS) bacteria in kefir grains, with its well-documented functional and health-promoting properties, constitutes a promising biopolymer with a variety of possible uses. Its compatibility with other biopolymers, such as milk proteins, and its ability to form standalone cryogels allow it to be utilized for the fabrication of films with improved properties for applications in the food and biomedical–pharmaceutical industries. In the present work, the properties of kefiran films were investigated in the presence of milk proteins (sodium caseinate, native and heat-treated whey proteins, and their mixtures), alongside glycerol (as a plasticizer) and cryo-treatment of the film-forming solution prior to drying. A total of 24 kefiran films were fabricated and studied for their physical (thickness, moisture content, water solubility, color parameters and vapor adsorption), mechanical (tensile strength and elongation at break), and optical properties. Milk proteins increased film thickness, solubility and tensile strength and reduced water vapor adsorption. The hygroscopic effect of glycerol was mitigated in the presence of milk proteins and/or the application of cryo-treatment. Glycerol was the most effective at reducing the films’ opacity. Heat treatment of whey proteins proved to be the most effective in increasing film tensile strength, reducing, at the same time, the elongation at break, while sodium caseinates in combination with cryo-treatment resulted in films with high tensile strength and the highest elongation at break. Cryo-treatment, carried out in the present study through freezing followed by gradual thawing of the film-forming solution, proved to be the most effective factor in decreasing film roughness. Based on our results, proper selection of the film-forming solution composition and its treatment prior to drying can result in kefiran–glycerol films with favorable properties for particular applications. Full article