Insect infestation attacks in agricultural ecosystems are becoming more common because of global warming as well as farmland environmental circumstances, necessitating the development of new crop production technology. Pesticide application is one of the most common strategies for protecting the entire growing period of plants or shrubs against pests and pathogens in farms. The rapid, effective, and profitable application of plant control substances via unmanned aerial vehicle (UAV) crop spraying is anticipated to be a key new technique. When compared to ground spraying, UAV spraying saves chemicals, water, time, does not damage crop plants or balls of crop, and does not create soil compaction. When using UAV, pesticide drift and deposition must be managed in order to use pesticides safely, effectively, and efficiently. This paper focuses on agrochemical spraying by unmanned aerial vehicles and the key parameters that influence spray effectiveness, such as the operating parameters of nozzle type, flying speed, flight height, type of nozzle, and type of UAV model, for reducing drift and increasing application efficiency. The multirotor UAV is most suitable for spraying due to its fast operation, safety, not requiring a runway for takeoff and landing, and lower cost as compared to fixed-wing and VTOL. UAVs can also be used for crop disease identification, soil health monitoring, livestock monitoring, field mapping, etc. This paper aims to review the development of various UAV models, optimization of operating parameters, effect of nozzle on UAV spraying, characterization of droplet deposition, drift reduction technology, UAV-based remote sensing for plant protection, and cost comparison of UAV to conventional ground sprayer.

Insecticidal interventions at critical stages of maize are an important strategy for managing invasive insect pest fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith). Conventional spraying systems cannot be used over larger areas, and the insecticide application using unmanned aerial vehicles is becoming popular among peasants. As the FAW resides inside the maize whorls, targeted insecticide application is necessary for effective management. The efficacy of (UAV) spray with different types of nozzles was compared with the conventional spray system, namely high -volume spray and Control droplet applicator. The other spray systems' droplet density, efficacy, and residues of insecticides in plants, soil and water were studied. The UAV droplet density up to 5 m swath recorded no significant variation for both nozzles. A UAV with an atomizer nozzle was as effective as a high -volume spray in reducing the FAW infestation. The residue analysis of leaf samples from the study area revealed more residues in the control droplet applicator and UAV atomizer nozzle. The per cent reduction of initial deposits in the top, middle and bottom maize leaves was least in the UAV atomizer nozzle. The insecticide residues in the study sample area were also below the detectable limit. UAV usage in maize saves time and reduces FAW damage as that of high -volume sprayers.

Soil electrokinetic (SEK) is a remarkable technology that has applications in a variety of fields, such as polluted soil remediation, soil restoration, geophysics, dewatering, seed germination, pollution prevention, sedimentation, and consolidation. The current review is a continuation of our recently published series on process design modifications and material additives. There are three reviews have been recently published. The 1st and 2nd reviews were focused on SEK classification according to electrode position/types of contaminants movement (horizontal, vertical, and mixed horizontal and vertical) during (1993-2020) [1] and (2021-2022) [2], respectively. The 3rd review summarized the materials additives for enhancing the SEK intensification process during 2017-2020 [3]. Modifications were made to the shape of the electrodes to make research and operation more convenient and efficient. Based on exhaustive searches in six scientific search engines, we focused on the various roles of utilizing the perforated electrodes, pipes (a tubular section, or hollow cylinder, made of hard plastic), and nozzles (a tubular section, or hollow cylinder, made of flexible plastic) (PEPN) during SEK. The PEPN could perform SEK properly, remove nitrate, collect drainage water, reduce pH advection, enhance materials injection, distribute water throughout treated soil, incorporate a vacuum system, and monitor wells. Although the perforated electrodes may be considered an economic advantage due to the reduction of electrode surface area and, consequently, total costs, no comparative studies have been conducted to determine the effects of different electrode surface areas on the SEK efficiency, operation time, and energy consumption, which should be considered in future research.

Simulation and accurate modeling of the mixing process of the high-pressure jet-cutting clay by the water-air coaxial nozzle is significantly important for the performance optimization of the triple fluid jet grouting. In this paper, a numerical model considering the soil rheological properties is proposed to investigate the mixing process of the high-pressure jet-cutting clay. The cohesive force model of clay is obtained based on the solution of the power law index and consistency factor by coupling the Herschel-Bulkley and soil logarithmic models. The interaction model among the gas phase, the liquid phase, and the clay medium is further established through use of the drag force model. A laboratory device of high-pressure jet-cutting transparent clay is developed to prove the feasibility of the proposed model for the mixing process of the high-pressure jet-cutting clay. Finally, using the validated numerical model, the mixing process of the high-pressure jet-cutting clay by the water-air coaxial nozzle with varying radial spacings between the air nozzle and water nozzle is numerically investigated, and the axial stability of the jet, the width of the cross-sectional profile, and the variation of the central axis velocity field of the mixing process are analyzed. Results demonstrated that the variation trend of the jet in both simulations and experiments is consistent, and the maximum error in jet depth is better than 3.3%, validating the accuracy of the numerical model of the mixing process of the high-pressure jet-cutting clay. The optimal radial spacing size for a water-air coaxial nozzle in high-pressure jetting of clay medium is 1.4 mm, which provides the best axial stability, the narrower jet cross-section, and the slowest decay of jet velocity along the central axis.