Search Results (104)

The integration of a real-time image processing system using multiple webcams with a variable rate spraying system mounted on the back of an unmanned tractor presents an effective solution to the labor shortage in agriculture. This research aims to design and fabricate a low-cost, variable-rate, remote-controlled sprayer specifically for use in sugarcane fields. The primary method involves the modification of a 15-horsepower tractor, which will be equipped with a remote-control system to manage both the driving and steering functions. A foldable remote-controlled spraying arm is installed at the rear of the unmanned tractor. The system operates by using a webcam mounted on the spraying arm to capture high-angle images above the sugarcane canopy. These images are recorded and processed, and the data is relayed to the spraying control system. As a result, chemicals can be sprayed on the sugarcane accurately and efficiently based on the insights gained from image processing. Tests were conducted at various nozzle heights of 0.25 m, 0.5 m, and 0.75 m. The average system efficiency was found to be 85.30% at a pressure of 1 bar, with a chemical spraying rate of 36 L per hour and a working capacity of 0.975 hectares per hour. The energy consumption recorded was 0.161 kWh, while fuel consumption was measured at 6.807 L per hour. In conclusion, the development of the remote-controlled variable rate sprayer mounted on an unmanned tractor enables immediate and precise chemical application through remote control. This results in high-precision spraying and uniform distribution, ultimately leading to cost savings, particularly by allowing for adjustments in nozzle height from a minimum of 0.25 m to a maximum of 0.75 m from the target. Full article

Swirl spray combustion has attracted significant attention due to its common usage in gas turbines. However, the high pressure in many practical applications remains a major obstacle to the deep understanding of flame stability and pollutant formation. To address this concern, this study investigated a swirl spray flame fueled with n-decane at elevated pressure. Planar laser-induced fluorescence (PLIF) of OH and polycyclic aromatic hydrocarbons (PAHs) were used simultaneously, enabling the distinction of the locations of OH, PAHs, and mixtures of them, providing detailed information on flame structure and evolution of PAHs. The effects of swirl number and ambient pressure on reaction zone characteristics and PAHs’ formation were studied, with the swirl number ranging from 0.30 to 1.18 and the pressure ranging from 1 to 3 bar. The data suggest that the swirl number changes the flame structure from V-shaped to crown-shaped, as observed at both atmospheric and elevated pressures. Additionally, varying swirl numbers lead to the initiation of flame divergence at distinct pressure levels. Moreover, PAHs of different molecular sizes exhibit significant overlap, with larger PAHs able to further extend downstream. The relative concentration of PAH increased with pressure, and the promoting effect of pressure on producing larger PAHs was significant. Full article

Modern nanoindentation equipment allows for highly precise measurements of mechanical properties such as hardness and elastic modulus, generating detailed load–unload curves using advanced techniques and specialised software. In this study, titanium coatings were deposited on various metallic substrates using cold gas spraying. Before deposition, the spraying parameters (temperature, pressure, velocity, and distance) were statistically optimised using the Taguchi method, reducing the number of experiments required from 81 to 9. This approach allowed the identification of optimal spray conditions (T = 731.0 °C, p = 33.0 bar, V = 343.6 mm/s, d = 35.5 mm), which were then applied to substrates including brass, steel, titanium, Al7075, copper, magnesium, and Al2024. Mechanical characterisation included hardness (H), reduced modulus (E), coating adhesion, and dissipated energy, calculated from the area of the load–unload hysteresis loop. Each coating–substrate combination underwent 36 nanoindentation tests, and adhesion was evaluated by pull-off tests. The initial results showed a poor correlation between adhesion and conventional mechanical properties (χ² of 17.1 for hardness and 16.2 for modulus, both with R² < 0.24). In contrast, the dissipated energy showed an excellent correlation with adhesion (χ² = 0.52, R² = 0.92), suggesting that dynamic deformation mechanisms better describe bonding. This introduces a new perspective to predict and optimise cold-spray adhesion in industrial applications. Full article

Quasicrystalline coatings based on Al₆₅Cu₂₀Fe₁₅ are of increasing interest as potential alternatives to conventional wear-resistant materials due to their unique structural and tribological properties. This study explores the influence of air pressure during high-velocity oxy-fuel (HVOF) spraying on the phase composition, morphology, and wear behavior of Al₆₅Cu₂₀Fe₁₅ coatings deposited on U8G tool steel. Coatings were applied at a fixed spraying distance of 350 mm using three air pressures (1.9, 2.1, and 2.3 bar), with constant propane (2.0 bar) and oxygen (2.1 bar) supply. X-ray diffraction analysis identified the formation of Al₇₈Cu₄₈Fe₁₄ and Al_0.5Fe_1.5 phases, while scanning electron microscopy revealed a dense, uniform microstructure with low porosity and homogeneous element distribution across all samples. Tribological testing using the ball-on-disk method showed wear track widths ranging from 853.47 to 952.50 µm, depending on the air pressure applied. These findings demonstrate that fine-tuning the air pressure during HVOF spraying significantly influences the structural characteristics and wear resistance of the resulting quasicrystalline coatings, highlighting their promise for advanced surface engineering applications. Full article

Rainfall simulators are essential tools in soil research, providing a controlled and repeatable approach to studying rainfall-induced erosion. However, the development of high-fidelity rainfall simulators remains a challenge. This study aimed to design, construct, and calibrate a spraying-type rainfall simulator and validate assessment criteria optimized for soil erosion research. The simulator’s design is based on a modified simulator model previously described in the literature and following the defined criteria. The calibration of the simulator was conducted in two phases, on slopes of 0° and 15°, measuring rainfall intensity, drop size, and its spatial distribution, and calculating drop falling velocity, kinetic energy, and momentum. The simulator consists of structural support, a water tank, a water-moving mechanism, a flow regulation system, and sprayers, contributing to its simplicity, cost-effectiveness, durability, rigidity, and stability, ensuring smooth simulator operation. The calibration of the rainfall simulator demonstrated that rainfall intensity increased from 1.4 mm·min⁻¹ to 4.6 mm·min⁻¹ with higher pressure in the hydraulic system (1.0 to 2.0 bar), while spatial uniformity remained within 79–91% across different nozzle configurations. The selected Rain Bird HE-VAN series nozzles proved highly effective in simulating rainfall, achieving drop diameters ranging from 0.8 mm to 1.9 mm, depending on pressure and nozzle type. The rainfall simulator successfully replicates natural rainfall characteristics, offering a controlled environment for investigating soil erosion processes. Drop velocity values varied between 2.5 and 2.9 m·s⁻¹, influencing kinetic energy, which ranged from 0.6 J·min⁻¹·m⁻² to 2.9 J·min⁻¹·m⁻², and impact momentum, which was measured between 0.005 N·s and 0.032 N·s. The simulator design suggests that it is suitable for future applications in both field and laboratory soil erosion research, ensuring repeatability and adaptability for various experimental conditions. Calibration results emphasized the significance of nozzle selection and water pressure adjustments. These factors significantly affect rainfall intensity, drop size, kinetic energy, and momentum, parameters that are critical for accurate erosion modeling. Full article

Research on water erosion often uses rainfall simulators, as these instruments allow for controlling the characteristics of the erosive agent and carrying out replications of experimental runs over brief time periods. In this paper, the early-step assessment of a new pressurized rainfall simulator equipped with nozzles differing in their spray angle and flow rate is developed. Experimental runs were performed to determine operative information about its functioning and rainfall intensity distribution. The investigated pressure–flow rate pairs, corresponding to values differing from those provided by the manufacturer, suggested that these nozzles are affected by their technological variability. Therefore, the use of the nozzles in pressure ranges that the producer did not investigate requires the testing of the manufacturer’s characteristic curves. The developed analysis on the variability of the measured average rainfall intensities and Christiansen’s Uniformity coefficient with the distance from the nozzle orifice demonstrates that the best simulation was obtained for the high-flow-rate nozzles at 120° and 90° with a pressure of 0.5 bar. These two simulation conditions allowed for the obtainment of rainfall intensities equal to 50 and 70 mm/h, respectively, and excellent uniform spatial distributions within a circular area with a diameter of 1.5 m. Moreover, to change the rainfall intensity during the simulation, the more effective approach was to maintain a constant pressure and modify the nozzle type, thereby modifying the nozzle spray angle. This finding underlines the importance of verifying the manufacturer’s nozzle characteristic curves and testing the rainfall intensity spatial distribution for selecting the nozzles most suitable for the simulation aims. Full article

In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, industrial chemicals, microplastics, organic matter combustion, agricultural practices, and plasticizer material. The principles of green analytical chemistry (GAC) and green sample preparation (GSP) serve as a guideline for the development of more environmentally sustainable analytical protocols. This study focuses attention on microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), matrix solid-phase dispersion (MSPD), and microextraction techniques, such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), spray-assisted droplet formation-based liquid-phase microextraction (SADF-LPME), and dispersive liquid–liquid extraction (DLLME). These approaches represent the most relevant eco-friendly sample preparation for the advanced extraction of target analytes from environmental solid samples. Full article

In this work, three catalysts, TiO₂, WO₃ and TiO₂/WO₃, have been synthesized through flame spray pyrolysis synthesis (FSP) and have been tested for CO₂ photoreduction. The catalysts were fully characterized by XRD, DRS UV–Vis, N₂ physisorption and SEM. Experimental tests were performed in a one-of-a-kind high-pressure reactor at 18 bar. TiO₂ P25 was used as a benchmark to compare the productivities of the newly synthetized catalysts. The two single oxides showed comparable productivities, both slightly lower than the P25 reference value (ca. 17 mol/kg_cat·h). The mixed oxide, TiO₂/WO₃, instead showed an impressive productivity of formic acid with 36 mol/kg_cat·h, which is around 2.5 times higher than both of the single oxides alone. The formation of a type-II heterojunction has been confirmed through DRS analysis. The remarkable productivity demonstrates how FSP synthesis can be a crucial tool to obtain highly active and stable photocatalysts. This approach has already been successfully scaled up for the industrial production of various catalysts, showcasing its versatility and efficiency. Full article

The combination of a liquid piston gas compressor and a solid metal insert can achieve a near-isothermal compression process, which can greatly contribute to improving the system efficiency of a compressed-air energy storage system. To examine the effectiveness of the insert at various pressure levels, compressions were performed in a liquid piston compressor with and without copper wire mesh inserts at three different pressures of 1, 2, and 3 bars. The use of inserts increased isothermal compression efficiencies by 8–10% from the baseline isothermal efficiencies about 83–87%, while the compromised air volume due to the inserts was minor. In addition to the solid insert-based technique analysis, a comparative study with other proven liquid-based heat transfer enhancement techniques, spray injection and aqueous foam, was performed. Not only was a quantitative analysis made comparing the isothermal efficiency values but the pros and cons of each technique’s distinctive working mechanisms were also compared. Full article

Diesel–methanol dual-fuel (DMDF) mode holds significant potential for achieving highly efficient and clean combustion in modern marine engines. However, issues such as low methanol substitution rate and high pollutant emissions persist, and the underlying mechanisms are not fully understood. This study numerically investigated the combustion and emissions of a heavy-duty marine engine operating in DMDF mode. Multi-cycle simulations, incorporating diesel and methanol dual-fuel chemical mechanisms, were carried out to explore engine performance across various key parameters, including valve phasing, injection pressure, injection phasing, and nozzle diameter. The results indicate that valve phasing can greatly affect the indicated thermal efficiency, particularly at large valve overlap angles. This is primarily attributed to the variations of methanol film mass and thereby overall combustion efficiency. The optimized valve phasing increases the indicated thermal efficiency by 2.4%. By optimizing injection parameters, the formation of methanol film is effectively reduced, facilitating the improvement in the indicated thermal efficiency. The optimal injection pressure and nozzle diameter are 20 bar and 0.3 mm, respectively, resulting in increases in indicated thermal efficiency of 1.28% and 1.07%, compared to the values before optimization. Advancing injection timing and increasing nozzle diameter markedly decrease methanol film mass because some methanol remains undisturbed by the intake flow, while large droplet sizes tend to enhance the resistance to airflow. As injection pressure rises from 20 bar to 50 bar, the spray–wall interaction region expands, droplet size diminishes, and methanol film formation increases. Consequently, the combustible methanol in the cylinder is reduced, undermining the indicated thermal efficiency. Additionally, there exists a trade-off relationship between NO_x and soot emissions, and the high heat release rate results in increased NO_x but decreased soot emissions for diesel–methanol dual-fuel engines. Full article

The research presented in this article seeks to identify the possible causes of reinforcement shadows (RS) on the surface of concrete test specimen produced under laboratory conditions. Different hypotheses about RS were selected based on factory practices and simulated in the study. The test specimens were cast horizontally in contact with steel form-facing surfaces coated with a water-soluble release agent. In addition, two scenarios were analysed during specimen production: reinforcing mesh was fixed using plastic spacers or tie wire. The analysis of the reinforcement shadows was based on visual inspection, taking photos, surface moisture content measurements, and colour variation analysis using the Natural Colour System. It was concluded that RS, which are typically characterized by darker lines, can be defined by the percentage of black colour present in the shadowed area compared to the percentage of black colour in the surrounding area. This percentage can be quickly assessed on a factory scale using digital colour readers that provide timely information. The reduced concrete cover thickness from 35 mm to 10 mm revealed light horizontal dark lines on the exposed surface. It was hypothesised that the gap of less than 10 mm between the reinforcing bars and the steel form-facing plate, along with the sieving effect of the fresh concrete, can retard the cement paste hydration process, resulting in unhydrated ferrite phases that contribute to the dark colour of the unhydrated cement. The release agent sprayed on the steel form-facing surface straight through the reinforcing mesh created a RS effect of the reinforcement on the exposed concrete surface. The absence of a release agent under steel rebars decreased the wettability at the interface between the formwork and fresh concrete, resulting in dark lines during the curing process. It is important to avoid such cases when manufacturing precast reinforced concrete elements. Quantitatively assessing RS and proposing a standardized method for calculation and categorization could be a new research direction in the future. Full article

In densely planted solar greenhouses, tomato crops face increasing challenges with pest and disease control due to high temperature and humidity conditions. The existing spraying equipment often suffers from low mechanization and inadequate foliar deposition coverage. This study presents the design of a vertical spray bar electrostatic sprayer, which combines a multi-nozzle vertical spray bar with electrostatic spraying technology, making it suitable for greenhouse applications. In order to obtain the best working parameters of the sprayer, the coverage rate of the front and back sides of the tomato leaves was taken as the performance target. Key influencing factors, including electrostatic voltage, spray pressure, and target distance, were investigated using a multi-factor response surface methodology. Field experiments were conducted in a greenhouse environment based on the optimized parameters to validate the performance. The results indicate that: (1) The factors influencing droplet adherence on the upper surface of tomato leaves ranked in the order of target distance, spray pressure, and electrostatic voltage, while for the underside, the order was electrostatic voltage, target distance, and spray pressure. (2) Under the conditions of electrostatic voltage of 10 kV, spray pressure of 0.7 MPa, and target distance of 35 cm, the sprayer achieves the optimal operation of leaf comprehensive coverage. (3) Compared to non-electrostatic spraying, the greenhouse electrostatic sprayer significantly improved the coverage on both sides of the leaves, enhancing pesticide utilization efficiency. This novel electrostatic sprayer meets the operational requirements for greenhouse crop protection in the Xinjiang region of China. Full article

Pesticide application development has grown exponentially in recent decades thanks to the implementation of new technologies and improved quality of spray input application. Electrostatic technology for increasing deposition has proven to be a suitable tool under specific study conditions, such as when working with very small droplet sizes, with air assistance, or typically in greenhouse environments. However, its effectiveness in hydraulic spraying, as well as its application from a commercial point of view in agriculture, is still challenging. The aim of this study was to evaluate the performance of this technology by implementing a modified lance on a small commercial knapsack sprayer, equipped with a hydraulic nozzle providing a range of droplet size values (Dv50) from 136 μm to 386 μm in the pressure range between 2 and 6 bar. This setup allowed operation under normal conditions (disconnected electrostatic system: NES) or with the connected electrostatic system (ES), with both configurations being tested in this study. Liquid distribution profiling as well as qualitative and quantitative evaluation of deposition were carried out both under laboratory conditions and in tomato crops under greenhouse conditions. The results showed no differences between the ES and NES in terms of flow rate (L min⁻¹) characterization or in the total accumulated volume collected with the vertical bench. The impact of the electrostatic system connection was clearly observed in laboratory trials, with total deposition increases of up to 66%. In field trials, this effect decreased in unexposed areas and in denser sections of the crop. However, the overall increase in deposition, mainly associated with the exposed side, continued to be significant. Full article

This article presents the results of research on the growth kinetics, microstructure (SEM/EDS/XRD), and corrosion behavior of Zn-5Al coatings obtained using a high-temperature hot dip process on B500B reinforcing steel. The corrosion resistance of the coatings was determined using the neutral salt spray (NSS) test (EN ISO 9227). Based on chemical composition tests in micro-areas (EDS) and phase composition tests (XRD), corrosion products formed on the coating surface after exposure to a corrosive environment containing chlorides were identified. In the outer layer of the coating, areas rich in Zn and Al were found, which were solid solutions of Al in Zn (α), while the diffusion layer was formed by a layer of Fe(Al,Zn)₃ intermetallics. The growth kinetics of the coatings indicate the sequential growth of the diffusion layer, controlled by diffusion in the initial phase of growth, and the formation of a periodic layered structure with a longer immersion time. The NSS test showed an improved corrosion resistance of reinforcing bars with Zn-5Al coatings compared to a conventional hot-dip-galvanized zinc coating. The increase in corrosion resistance was caused by the formation of beneficial corrosion products: layered double hydroxides (LDH) based on Zn²⁺ and Al³⁺ cations and Cl⁻ anions and simonkolleite—Zn₅(OH)₈Cl₂·H₂O. Full article

Microbial contamination can occur on the surfaces of blow-molded bottles, necessitating the development and application of effective anti-microbial treatments to mitigate the hazards associated with microbial growth. In this study, new methods of incorporating anti-microbial particles into linear low-density polyethylene (LLDPE) extrusion blow-molded bottles were developed. The anti-microbial particles were thermally embossed on the external surface of the bottle through two particle deposition approaches (spray and powder) over the mold cavity. The produced bottles were studied for their thermal, mechanical, gas barrier, and anti-microbial properties. Both deposition approaches indicated a significant enhancement in anti-microbial activity, as well as barrier properties, while maintaining thermal and mechanical performance. Considering both the effect of anti-microbial agents and variations in tensile bar weight and thickness, the statistical analysis of the mechanical properties showed that applying the anti-microbial agents had no significant influence on the tensile properties of the blow-molded bottles. The external fixation of the particles over the surface of the bottles would result in optimum anti-microbial activity, making it a cost-effective solution compared to conventional compounding processing. Full article