Search Results (67)

This study aims to address the issues of high tool wear rate, severe deterioration of machining accuracy, and surface integrity in thin-walled part cutting processes, which are caused by vibration. To do so, this paper proposes a thin-walled part processing vibration control method based on CFS. With aluminum alloy 6061 planar thin-walled parts as the object of study, in this paper a CFS experimental platform was established, the influence of CFS on the dynamic characteristics of the thin-walled parts was analyzed, the effects of milling force and processing vibration during thin-walled part milling were investigated. The results show that compared with UCFS, CFS can significantly reduce the acceleration response amplitude of thin-walled parts and shorten their vibration decay time. When the spraying point coincides with the hammering point, the optimal vibration suppression effect is achieved at a spraying velocity V of 13 m/s, a spraying area S of 31 mm², and a spraying angle θ of 30°; the acceleration response amplitude decreases by 76.2%, and the vibration attenuation time decreases by 74.7%. This method can provide a certain support force and damping effect for thin-walled parts by CFS, thus reducing the milling force and machining vibration. Full article

This paper studied the atomization characteristics of different spray nozzles under the spot spraying method and designed a test system for the atomization characteristics. First, the effective spray height range was determined based on the effective droplet size of 106–403 μm, the spray height of 200–500 mm, the operating speed of 0.5–1 m/s, and the droplet size requirements. The effective height ranges of the HVV25-02, HVV40-02, and HVV50-02 nozzles are 277–500 mm, 200–426 mm, and 200–266 mm, respectively. Second, the influences of pressure, the opening time of the solenoid valve, and the nozzle aperture on the atomization characteristics were studied through experiment. The experiment was repeated three times, with 10,000 points monitored each time. The test results show that the droplet size of spot spraying decreases with the increase in pressure, while the droplet velocity and droplet distribution relative span have no correlation with pressure. With the increase in the opening time of the solenoid valve, the droplet size does not change regularly, the droplet velocity generally shows an upward trend, and the droplet distribution relative span (RS) value decreases gradually. With the increase in the nozzle aperture, both droplet size and droplet velocity increase, and the distribution span shows a trend of first increasing and then decreasing. The droplet velocity of spot spraying is 4.1 m/s lower than that of continuous spraying, on average, and the droplet distribution relative span value is 2.2 higher than that of continuous spraying. This research can provide a basis and reference for the selection of appropriate spot spraying operation parameters. Full article

This paper designs a Dual path cold spray nozzle and studies its performance during the cold spray process through numerical simulations and optimization experiments. The gas flow field inside the nozzle and the particle acceleration process were simulated using Fluent software2020R1. The orthogonal experimental method was used to analyze the effects of five geometric parameters on the nozzle performance, determining the optimal design parameter combination. Modeling and simulation calculations based on the optimal parameter combination showed that the average particle impact velocity increased by nearly 17 m/s, the number of particles exceeding the theoretical critical velocity increased by nearly 100, and the theoretical deposition efficiency improved by 10%. Experimental results indicated that compared to the single-channel nozzle, the deposition efficiency increased from 20.22% to 28.26%, the porosity improved from 10.51% to 9.12%, and the deposition microhardness also increased. The experimental test data were in good agreement with the previous numerical simulation results, validating the accuracy of the simulation model and providing an important theoretical reference for the optimization and improvement of subsequent process parameters. Full article

With the rapid development of precision agriculture spraying technology, the evaluation and detection of deposition effects have gradually become research hotspots. Rhodamine-B is often used for the quantitative elution detection of droplet deposition due to its fluorescent properties. In contrast, the method of detecting droplet deposition using water-sensitive paper (WSP) is simple to operate. However, it often faces issues with measurement accuracy due to factors such as irregular droplet diffusion and the excessive hydrophilicity of the sampler material. Based on this, the study proposes a method for correcting WSP deposition assays by using the quantitative elution of chemical colorants as a baseline reference. Experiments were conducted using a DJI T30 unmanned aerial spraying system (UASS) as the spray carrier, with four types of samplers—Ginkgo biloba leaves (GBL), Malus spectabilis leaves (MS), polyvinyl chloride (PVC) cards, and WSP—fixed at nine different angles. The deposition amounts of five concentrations of Rhodamine-B stain sprayed on the samplers were then compared. The results indicate that the correction factor can be influenced by various factors, including the environment, the type of sampler, the concentration of the sprayed colorant, and the angle of the sampler. Deposition correction coefficients for WSP with different samplers were determined to be in the ranges of 1.507 to 1.547 (WSP–GBL), 1.471 to 1.478 (WSP–MS), and 1.312 to 1.391 (WSP–PVC), respectively. The study confirmed the feasibility of the proposed fluorescence-corrected aerial spray droplet deposition method, which retains the advantages of two existing typical deposition determination methods. Additionally, pre-tests should be tailored to experimental conditions, and the choice of colorant concentration should be carefully considered. Full article

Tantalum (Ta), along with its compounds and alloys, is extensively applied in the chemical, electronic, biological, and aerospace industries due to its excellent ductility, thermodynamic stability, and corrosion resistance. In recent years, coatings of Ta and its composites, fabricated using methods such as magnetron sputtering (MS), chemical vapor deposition (CVD), electrospark deposition (ESD), and cold spraying (CS), have undergone significant performance enhancements through extensive research efforts. This paper provides a comprehensive overview of the preparation techniques, applications, and improvement techniques associated with Ta and its compounds’ coatings. The preparation process parameters, mechanical properties, and corrosion resistance of Ta alloy coating and Ta non-metallic compound coating are discussed in detail. The findings aim to contribute to the design and development of innovative Ta and its compounds’ coating systems or the refinement of existing systems. Full article

In this paper, a series of graded Al-based composites, including Al@AP, Al@AP/BM−52, and Al@AP/BPE−1735, have been prepared by spray drying technology. The thermal decomposition characteristics, kinetic parameters of the decomposition reaction, and Pyro-GC/MS products were comprehensively investigated. The results showed that two inhibitors, BM−52 and BPE−1735, had a significant effect on the thermal decomposition of AP. The addition of BM−52 conspicuously enhanced the thermal interaction, resulting in a more complete decomposition reaction of AP. Meanwhile, the incorporation of BPE−1735 significantly enhanced the heat releases of AP, leading to a significant enhancement in the energetic performance during the decomposition process of AP. BM−52 and BPE1735 inhibit AP decomposition as evidenced by higher activation energies for thermal decomposition and altered physical models of decomposition. Pyro-GC/MS results reveal that the fundamental pathway of Al@AP thermal decomposition remains unaltered by BM−52. However, the proportion of oxygen-containing compound products is moderately reduced. In contrast, for Al@AP/BPE−1735, in addition to the same products as those from Al@AP pyrolysis, new pyrolysis peaks emerge. It is implied that specific chemical reactions or interactions are triggered during the thermal decomposition process, thereby resulting in the formation of distinct chemical species. Full article

Based on the characteristics of small agricultural machinery in terms of flexibility and high efficiency when operating in small plots of hilly and mountainous areas, as well as the demand for improving the automation and intelligence levels of agricultural machinery, this paper conducted research on the path tracking control of the automatic navigation operation of a crawler sprayer. Based on the principles of the kinematic model and the position prediction model of the agricultural machinery chassis, a pure pursuit controller based on adaptive look-ahead distance was designed for the tracked motion chassis. Using a lightweight crawler sprayer as the research platform, integrating onboard industrial control computers, sensors, communication modules, and other hardware, an automatic navigation operation system was constructed, achieving precise control of the crawler sprayer during the path tracking process. Simulation test results show that the path tracking control method based on adaptive look-ahead distance has the characteristics of smooth control and small steady-state error. Field tests indicate that the crawler sprayer exhibits small deviations during path tracking, with an average absolute error of 2.15 cm and a maximum deviation of 4.08 cm when operating at a speed of 0.7 m/s. In the line-following test, with initial position deviations of 0.5 m, 1.0 m, and 1.5 m, the line-following times were 7.45 s, 11.91 s, and 13.66 s, respectively, and the line-following distances were 5.21 m, 8.34 m, and 9.56 m, respectively. The maximum overshoot values were 6.4%, 10.5%, and 12.6%, respectively. The autonomous navigation experiments showed a maximum deviation of 5.78 cm and a mean absolute error of 2.69 cm. The proportion of path deviations within ±5 cm and ±10 cm was 97.32% and 100%, respectively, confirming the feasibility of the proposed path tracking control method. This significantly enhanced the path tracking performance of the crawler sprayer while meeting the requirements for autonomous plant protection spraying operations. Full article

This paper discusses the process of high-velocity oxygen fuel (HVOF) spraying with modeling of the gas flow parameters and behavior of WC-Co-Cr powder particles of different fractions (up to 20 µm, 21–35 μm and 36–45 μm). It was found that the temperature of the gas stream reaches a maximum of about 2700 °C, after which it gradually decreases, and the pressure in the combustion chamber (before the exit of gases through the nozzle) reaches maximum values, exceeding 400,000 Pa, and the pressure at the exit of the nozzle stabilizes at about 100,000 Pa, which corresponds to the standard atmospheric pressure. The gas velocity increases to 1300–1400 m/s and then decreases to 400 m/s at a distance of about 150 mm. It was determined that powder particles of the 21–35 µm fraction provide more stable parameters of velocity and temperature. Small particles (up to 20 µm) lose velocity and temperature faster as they advance, which deteriorates the coating quality, which was also experimentally confirmed. All results obtained from the HVOF process modeling fully align with the data from experimental studies. Full article

This paper presents an air-assisted sprayer for vineyard pesticide application. The spraying unit was designed with two symmetrically arranged ports. The airflow velocity distribution of the sprayer was investigated using a combination of experimental validation and a computational fluid dynamics (CFD) model. The results of both the simulation and the experiment showed good agreement in airflow velocity, and the distribution was uniform. Both unilateral and bilateral spraying field experiments were conducted in this study. The unilateral spraying experiment showed that higher spray pressure and lower sprayer speed increased both total deposition coverage and spray penetration (SP), while shorter spray distances improved SP but decreased total deposition coverage. The optimal operational conditions for the sprayer were determined as follows: spray pressure of 0.40 MPa, sprayer speed of 0.83 m/s, and spray distance of 1.00 m. The results of the bilateral spraying field experiment indicated that the coefficient of variation (CV) for deposition coverage in Columns A, B, and C were 16.20%, 8.10%, and 15.47%, respectively. The CVs in Layers a, b, and c were 6.14%, 12.62%, and 6.74%, respectively. This result demonstrated that the deposition coverage distribution in the canopy was relatively uniform, and the air-assisted sprayer exhibited good spray penetration performance. This study demonstrates the effectiveness and potential of the air-assisted sprayer for vineyard pesticide application. Full article

The plasma bulk velocity is one of the key parameters describing the behavior of a plasma jet and is relevant for applications such as plasma spraying or electric propulsion. Therefore, different measurement techniques to determine the velocity were developed in the past. This paper presents a novel, non-invasive method for spatially resolved velocity measurements. The method is based on tracking of characteristic features in tomographic reconstructions of the plasma plume. A high-speed image recording system combined with tomographic acquisition is therefore the backbone of this method. The proposed setup captures the object under study from six different directions at a frame rate up to one million frames per second, providing high spatial and temporal resolution. The tomographic reconstructions are then calculated using the ART algorithm to track features in the plasma fluctuations, from which the bulk velocity is determined. The setup was tested with a DC plasma torch operated at reduced pressures in the range of tens of millibars. For the analyzed parameters, the axial velocity reached a maximum of 1061 m/s at a distance of three centimeters from the plasma torch exit and decreased to 919 m/s further downstream at a distance of seven centimeters, which is in good accordance with previous work. Therefore, the proposed diagnostic method can serve as a non-invasive alternative to velocity measurements, providing additional information in the form of a 3D model of the plasma bulk. Full article

As a prescription drug, retinoic acid is listed as a banned cosmetic additive in the EU and China regulations. Currently, spectrophotometric methods, including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and HPLC–MS/MS, are commonly used for the determination of retinoic acid. As these conventional methods require complex pretreatment and are time-consuming, chemical derivatization combined with paper spray ionization mass spectrometry was developed for the fast detection of retinoic acid in cosmetics. N,N-dimethylpiperazine iodide (DMPI) was utilized as a derivatization reagent. Carboxylic acid in retinoic acid was derivatized to carry a positive charge and was subjected to mass spectrometry analysis. Results showed that compared with non-derivatized compounds, the detection limit was increased by about 50 times. The linearity in the range of 0.005–1 μg·mL⁻¹ was good. The limit of detection (LOD) was 0.0013 μg·mL⁻¹, and the limit of quantification (LOQ) was 0.0043 μg·mL⁻¹. The recoveries of spiked samples were in the range of 95–105%, and the RSDs were below 5%. Derivatization and paper spray ionization MS render a quick, sensitive, and accurate method for the detection of retinoic acid in a complex matrix. Full article

This work reports on the development of an analyte sampling strategy on a plasmonic substrate to amplify the detection capability of a dual analytical system, paper spray ionization–mass spectrometry (PSI-MS) and surface-enhanced Raman spectroscopy (SERS). While simply applying only an analyte solution to the plasmonic paper results in a limited degree of SERS enhancement, the introduction of plasmonic gold nanoparticles (AuNPs) greatly improves the SERS signals without sacrificing PSI-MS sensitivity. It is initially revealed that the concentration of AuNPs and the type of analytes highly influence the SERS signals and their variations due to the “coffee ring effect” flow mechanism induced during sampling and the degree of the interfacial interactions (e.g., van der Waals, electrostatic, covalent) between the plasmonic substrate and analyte. Subsequent PSI treatment at high voltage conditions further impacts the overall SERS responses, where the signal sensitivity and homogeneity significantly increase throughout the entire substrate, suggesting the ready migration of adsorbed analytes regardless of their interfacial attractive forces. The PSI-induced notable SERS enhancements are presumably associated with creating unique conditions for local aggregation of the AuNPs to induce effective plasmonic couplings and hot spots (i.e., electromagnetic effect) and for repositioning analytes in close proximity to a plasmonic surface to increase polarizability (i.e., chemical effect). The optimized sampling and PSI conditions are also applicable to multi-analyte analysis by SERS and MS, with greatly enhanced detection capability and signal uniformity. Full article

The strong airflow beneath a rotary drone generates a wind vortex within the rice canopy; precise control of the wind vortex distance and wind vortex area can improve pesticide utilization efficiency. This paper calculates the flight parameter curve based on the wind vortex target from the wind vortex target parameter control model of the four-rotor plant protection drone, designs a flight control system using a Cube Orange flight controller and a Jetson AGX Xavier onboard computer, and implements flight parameter control using both PID control and fuzzy control algorithms. Experimental results indicate that when using PID control and fuzzy control, the average deviation values of UAV flight altitude and speed are 0.08 m, 0.08 m/s, 0.06 m, and 0.08 m/s, respectively. When using PID control, the average distance and area errors of the target downwind and upwind are 0.17 m and 0.37 m² and 0.20 m and 0.46 m², respectively. The corresponding values for fuzzy control are 0.12 m, 0.38 m², 0.09 m, and 0.31 m². In the twelve voyage experiments, the target parameter variance using fuzzy control was relatively smaller for eight voyages compared to PID control, which had a smaller variance for four voyages. On the whole, the effect of fuzzy control is superior. The wind vortex control method proposed in this paper can effectively enable precise pesticide spraying by drones. This has significant implications for reducing agricultural production costs and safeguarding the natural environment. Full article

The pequi (Caryocar brasiliense) fruit peel, despite being frequently discarded, has a high content of bioactive compounds, and therefore has a high nutritional value. The present study aimed to explore the bioactivities in the pequi peel, particularly their potential health benefits at the level of antioxidant activity. The exploitation of this fruit could also present significant economic benefits and applications of pequi by-products would represent a reduction in waste, having a positive impact on the environment. Phenolic compounds present in the pequi exocarp and external mesocarp were identified by paper spray mass spectrometry (PS-MS) and quantified by HPLC. The total phenolic content (TPC) along with the amount of 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Antioxidant Power (FRAP), and the amount of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) were also determined in peel extracts. Epicatechin was the most abundant phenolic compound found, followed by the caffeic, salicylic, and gallic acids. In addition, fingerprinting revealed compounds related to several beneficial health effects. In short, the results obtained were encouraging for potential applications of pequi peel in the field of functional foods. Full article

Mass spectrometry (MS) is a highly selective and sensitive analytical tool with a myriad of applications, but such techniques are typically used in laboratory settings due to the handling and preparations that are necessary. The merging of two streams of robust research, portable MS systems and next-generation ambient ionization methods, now provides the ability to perform high-performance chemical screening in an on-site and on-demand manner, with natural applications in disciplines such as forensic science, where samples of interest are typically found in field environments (i.e., traffic stops, crime scenes, etc.). Correspondingly, investigations regarding the suitability and robustness of these methodologies when they are utilized for authentic forensic evidence processing are prudent. This work reports critical insights into the role that choice of spray solvent system plays regarding analytical performance of two spray-based ambient ionization sources, paper spray ionization (PSI) and filter cone spray ionization (FCSI), when employed for evidence types containing emerging synthetic cannabinoids. The systematic characterization studies reported herein show that the applied spray solvent can dramatically affect both spectral intensity and signal duration, and in some circumstances, yield deleterious false negative responses. Overall, acetonitrile-based systems are shown to strike a balance between analyte solubility concerns and spray ionization dynamics of the novel ion sources employed on portable MS systems. Full article