Air Blast Research Articles

Avoidance of hot air blast in Rattus norvegicus.

The hegemonic use of electric shock as an aversive stimulus limits what is known about the generality of avoidance behavior and related phenomena. The purpose of this study was to investigate the effects of using the hot air blast (HAB) instead of electric shock as an aversive stimulus in avoidance conditioning. Four male Wistar rats were exposed to a discrete-trial procedure. In the first phase, the emission of a lever-press response during a trial was positively reinforced. In the second phase, the same contingency was employed, but an escapable HAB was presented at the end of a trial when no response was emitted. In the third phase, positive reinforcement was suspended and a discrete-trial avoidance procedure was employed. In the fourth phase, HAB presentation was completely suspended. As a result, all subjects learned the avoidance response and showed a marked reduction in its frequency during HAB suspension. These results offer evidence indicating that avoidance behavior is controlled by the HAB, thereby advancing the understanding of the generality of this stimulus as being aversive.

Porcine blast injury model achieves prolonged elevation of intra-compartmental pressures without exogenous pressure manipulation

BackgroundMost existing animal models of acute compartment syndrome (ACS) rely on exogenous manipulation of intra-compartmental pressures to model ACS. The purpose of the current study was to evaluate the endogenous effect of a blast injury on porcine lower leg intra-compartmental pressures (ICP).MethodsThe hindlimb of juvenile Landrace pigs was fractured at the diaphyseal tibia and subjected to blasts of compressed air to mimic a blast injury. Injured and control legs underwent pre-operative continuous ICP monitoring. At 4.5 h post injury, the fracture was stabilized followed by closure of the anterior compartment fascia (continued compartment pressure model, CCPM) or four compartment fasciotomy. Pressure measurements were made after operative fixation. Select pigs in CCPM were harvested between 48 and 72 h post-injury to evaluate the duration of ICP elevation.ResultsPost-injury, the model created significantly elevated ICP compared to control limbs (54.5 ± 18.2 vs. 18.2 ± 4.9 mmHg; p < 0.001). Operative fixation and anterior compartment fascial closure further increased the ICP (Mean: 87.4 ± 42.5 mmHg) relative to the pre-operative state (p = 0.037). Fasciotomy returned baseline compartment pressures (Mean: 13.7 ± 10.2 mmHg) which were equivalent to control limbs (p = 0.117). Pressure measurements at the time of delayed harvest (48–72 h) demonstrated that elevated ICP persisted following injury (69.7 ± 55.12 mmHg).ConclusionThe current study demonstrates that a pilot porcine blast model elevates ICP comparable to existing animal models of compartment syndrome without exogenous ICP manipulation. ICP remained elevated at 48–72 h in the absence of fasciotomy.

Air blast resistance of ARMOX 500T Steel plates with standard thickness: Experimental and numerical consideration

The numerical and experimental examinations in the behavior of ARMOX 500 T steel plates of a standard thickness under blast loading are presented in this study. Furthermore, the dynamic reaction of the steel plate is crucial, particularly when subjected to blast loads produced by various explosive forms and at a certain stand-off distance (SoD). This study conducted experimental and numerical simulation tests on steel plates under the close-range air blast loads generated by 150 g TNT cylindrical explosives, which are the most widely used explosives in the military and engineering fields. In order to investigate the failure modes of steel plates, close-range air blast load experiments were conducted at a 400 mm SoD. Pressure gauges were positioned at equal distances, and the impact of these tests on the failure deformation and dynamic response of the steel plate was quantitatively examined. Ultimately, the properties of shock waves produced by cylindrical explosives were examined in order to ascertain how SoD and charge quantity affected the shock waves' spatial dispersion.

Variable air blast fireball of HMX/Al with tailored gradient structures

Air blast fireball of the composite explosive is an important way to destroy the target and effectively determines the damage effect. Herein, based on the effect of aluminum powder content on the explosion reaction kinetics of HMX-based aluminized explosives, the cylindrical charges with positive gradient structure (PGS) and negative gradient structure (NGS) were designed and prepared to control the structure and size of air blast fireball. The PGS cylinders exhibited lateral shuttle-shaped flame/fireball and the width of the fireball was 3.901 m, which was increased by about 14% compared with homogeneous cylinders. The NGS cylinders led to the vertical shuttle-shaped flame/fireball that the height of the air blast fireball reached 4.049 m, and had longer durations of the fireball. The numerical fitting results show that the lateral shuttle-shaped flame/fireball and vertical shuttle-shaped flame/fireball gradually changed into spherical-like flame/fireball with an increase from 0 to 30 wt% of outer and inner layer HMX content, respectively. The vertical shuttle flame/fireball gradually changed into a spherical-like flame/fireball with the increase of HMX content. This is a feasible way to regulate the shape and size of the air blast fireball through gradient adjusting the distribution of HMX and Al, which could provide an effective strategy to improve the damage effect.

UGV‐Based Precision Spraying System for Chemical Apple Blossom Thinning on Trellis Trained Canopies

ABSTRACTBlossom thinning is one of the key steps in apple crop load management that improves the quality of apples, reduces stress on the trees, and avoids the likelihood of biennial bearing. Conventional chemical blossom thinning such as air‐blast spraying can lead to excessive use of chemical thinner to ensure full coverage, which can also cause leaf damage fruit russeting. In addition, a well‐trained operator is required to use these chemical spraying systems. To address these challenges, a UGV‐based precision spraying system was developed for automated and targeted chemical blossom thinning for apples. The system is capable of automatically driving along the tree row in the orchard environment during blooming stage, locating apple flower clusters to be thinned using a real‐time machine vision system, and precisely spraying the chemical thinner to the targeted flower clusters. A set of field tests were conducted to evaluate the performance of the UGV‐based target spraying system by comparing it to a conventional air‐blast sprayer (ABS) and a previous prototype named the cartesian target sprayer (CTS). Tests showed that the flower cluster detection reached a precision of 93.8%. The UGV‐based spraying system used 2.2 L of chemical thinner to finish the chemical thinning for 30 apple trees, followed by the ABS and CTS with 4.2 and 2.4 L usage, respectively. The robotic system also obtained an average fruit set of 2.2 per cluster after thinning, which was comparable to that with the air blast sprayer. The findings indicated that the robotic thinning system demonstrated a 66.7% reduction in chemical usage compared to the ABS and exhibited a 43.0% faster operational pace than the CTS, while attaining a comparable fruit set per cluster. The outcomes of the study provided guidance for developing a full scale robotic chemical thinning system for modern apple orchards.

An earthquake-triggered avalanche in Nepal in 2015 was exacerbated by climate variability and snowfall anomalies

On 25 April 2015, the Gorkha earthquake triggered a large rock-ice avalanche and an air blast disaster in the Langtang Valley, Nepal. More than 350 people were killed or left missing. Here we reconstruct the evolution of the Langtang avalanche-air blast using field investigations and numerical modeling and examine the influence of two primary climate-related phenomena: snowfall anomalies and warm temperatures. Our findings suggest a deep snow cover fosters the formation of a dispersed avalanche, which increases the mobility and destructive power of the powder cloud air blast. Elevated air temperatures intensify meltwater production and lubricate the flowing mass. Both mechanisms contributed to the Langtang disaster. Our study underscores the essential impact of snow cover and air temperature on the risk assessment of high-altitude rock-ice avalanches, highlighting how seasonal and climatic variations affect avalanche runout and air blast dynamics.

Experimental and numerical investigations on dynamic response of butt-welded plates subjected to blast load

Experimental and numerical investigations on the small-size butt-welded plates subjected to air blast loads were conducted to highlight the effect of welded joints on the blast proof structures. The inherent characteristics of welded joints, including geometry, mechanical properties and welding residual stress were evaluated and discussed in the computation of blast loading. The geometry shape was assessed through macrographic of the welded joints. The distribution of mechanical and thermal physics property was determined through basic experiments using the specimens extracted from different zones of a welded joint. Welding residual stress was calculated in a thermo-mechanical coupled model. Conventional Weapons Effects Program (CONWEP) is more economic but limited compared with Arbitrary-Lagrangian–Eulerian (ALE) method. ALE and CONWEP methods were applied to simulate the air blast load applied on the plates. Effectiveness and efficiency of the methods were discussed. The results of the two programs could both coincide well with the experiment measurements. The models under six conditions were calculated to uncouple and discuss the effect of material property distribution and welding residual stress on the dynamic response of the welded structure. Permanent deflections were considered to assess the capacity of welded structures. Welding residual stress fields and the local weak materials are advantageous to the bending deformation. The phenomenological expressions of permanent deflection across thickness under different welding conditions were established based on simulation results. The effect of aspect ratio of the welded structures was also be discussed.

Enhancing blasting efficiency: A smart predictive model for cost optimization and risk reduction

Mineral extraction involves distinct stages, including drilling, blasting, loading, transporting, and processing minerals at a designated facility. The initial phase is drilling and blasting, crucial for controlled dimensions of crushed stone suitable for the processing plant. Incorrect blasting can lead to unsuitable stone grading and destructive outcomes like ground vibrations, stone projection, air blasts, and recoil. Predicting and optimizing blasting costs (BC) is essential to achieve desired particle size reduction while mitigating adverse blasting consequences. BC varies with rock hardness, blasting techniques, and patterns. This study presents a BC prediction model using data from 6 Iranian limestone mines, employing firefly (FF) and gray wolf optimization (GWO) algorithms. With 146 data points and parameters like hole diameter (D), ANFO (AN), sub-drilling (J), uniaxial compressive strength (σc), burden (B), hole number (N), umolite (EM),spacing (S), specific gravity (γr), stemming (T), hole length (H), rock hardness (HA), and electric detonators (Det), the data was split into 80% for model construction and 20% for validation. Using statistical indicators, the model showed good performance, offering engineers, researchers, and mining professionals high accuracy. The @RISK software conducted sensitivity analysis, revealing T parameter as the most influential input factor, where minor T changes significantly affected BC. Lastly, the @RISK software was employed to conduct a sensitivity analysis on the model's outputs. The analyses demonstrated that, among the input factors, the T parameter had the most pronounced effect on the model's output. Even small changes in the value of T led to considerable fluctuations in the predicted BC.

A Comparative Blast Mitigation Performance Evaluation of Metallic Sandwich Panels with Honeycomb, Corrugated, Auxetic, and Foam Cores

Due to the high energy absorption capability and excellent bending strength of the sandwich panels, they are mostly preferred as protective structures against explosive blast attacks. The evaluation of their blast-mitigation characteristics through experiments is highly dangerous, costly, time-consuming, and polluting for the environment. Therefore, in this presented work, a series of numerical analyses were performed to evaluate the blast mitigation of the outstanding sandwich panels with honeycomb, corrugated, auxetic, and foam cores. The masses of sandwich panels were kept constant, and their areal densities were maintained constant throughout the study to effectively compare their performance under identical air blast loading conditions. To apply the air blast loads to the designed sandwiches, 1–3[Formula: see text]kg of spherical-shaped trinitrotoluene charges were used for a 100[Formula: see text]mm stand-off distance. The sandwiches are made of high-strength AL-6XN steel and crushable aluminum foam. The rate-dependent Johnson–Cook constitutive model of plasticity and the crushable foam model with volumetric hardening were used for the evaluation of sandwich panels’ plastic deformations. The findings of the work depicted that the honeycomb core is more efficient than the other core structures of the same masses because the sandwich panels with honeycomb core provide smaller back skin deflections, globalized core crushing, and higher core energy absorption than the other sandwich panels for extreme conditions of air blast loading.

Coaxial air blast atomization of a particulate gel suspension jet

The objective of this study is to experimentally and theoretically explore the impact of particle volume fractions and nozzle thread structure on the coaxial air blast atomization of particulate gel suspension jets through the high-speed flow visualization technology. The four breakup modes of particulate gel suspension jets are confirmed, namely oscillation mode, membrane-type breakup, fiber-type breakup, and superpulsating submode. However, the fiber-type breakup of jets disappears as the particle concentration reaches 40%, primarily attributed to the numerous particles sharply promoting the instability on the free jet surface. The experimental statistical results demonstrate that an increase in particle concentration and the adoption of the threaded nozzle both result in an expansion of the jet spray angle. The breakup length exhibits a reduction trend with the increase of particle concentration. However, it remains nearly the same value as that in the case of volume fraction 20% when the particle concentration continues to increase, contributed by the surge of viscous dissipation counteracting the enhanced instability on the jet interface caused by a large number of particles. The breakup length of a pure gel jet is predicted through the linear instability analysis, which is further modified by the viscosity model of particle suspensions to derive the breakup lengths of particulate gel suspension jets with different concentrations. The theoretical predictions align well with the statistical results in the experiment. The research is poised to have potential implications for numerous industrial processes and engineering applications including gel propellants.

Thermomechanical effects during air blast freezing of fruit pulp model solutions with different sucrose concentrations in metal drums

The strains on the metal drums surfaces caused by the ice volumetric expansion during the freezing of model solutions of fruit pulps were evaluated by extensometers. 200 kg of model solutions of 0.5% k-carrageenan (w/v) added 0.5%, 10% or 20% (w/v) sucrose into metal drums were frozen in air blast freezer at −25 °C. Strain gauge sensors were installed on the side surface and bottom of the drums in a balanced Wheatstone bridge circuit. The resulting stresses and temperature profiles inside the packages were measured simultaneously. The non-uniform temperature distribution in the product was proven by IR thermography. There was reduction in the freezing temperature and stresses in the packages with the increase in the sucrose concentration. The restricted surfaces, preventing the expansion of the ice, yielded great stresses in the frozen solutions and induced cracking in the free surfaces of the solutions, especially in the systems with lower concentrations.

Effects of typical MH2 (M= Ti, Mg, Zr) on the detonation energy release characteristics of composite charge containing Al/PTFE reactive materials and RDX

To explore the effects of three typical metal hydride powders (TiH2, MgH2, ZrH2) on the detonation energy release characteristics of composite charge containing Al/PTFE reactive materials and RDX, a variety of composite charges containing Al/PTFE/MH2 ternary active materials and RDX were prepared. The effects of metal hydrides on detonation parameters of composite charges were studied by air blast experiments and the temperature distributions of explosion fireball were mapped using colorimetric thermometry technique. The experimental results indicated that the addition of metal hydrides had significantly positive effects on afterburning effect and detonation performance of composite charges, and the enhancement effect of MgH2 was superior to that of TiH2 and ZrH2. The fireball duration, maximum average temperature and shock wave parameters of the composite charges in air blast experiments all changed with the order of Al/PTFE/MgH2+RDX > Al/PTFE/TiH2+RDX > Al/PTFE/ZrH2+RDX > Al/PTFE + RDX. The results could offer theoretical references for the formulation design of high-power explosives.

Cryoprotective role of vacuum infused inulin on the quality of artichoke: Interactive effects of freezing, thawing and storage period

Freezing of artichoke is a promising alternative to storing it in brine and canning. The perishable vegetable was vacuum infused with inulin to improve freezing tolerance. Artichokes with and without inulin were frozen by static, air blast and individual quick freezing (IQF) methods and thawed by microwave, 25 °C and 4 °C temperature levels at each month of 6-months storage. Process conditions were evaluated by multivariate analysis of variance (MANOVA) and were found significant on the quality parameters. Inulin infusion better conserved the aw, color, texture, ascorbic acid and overall integrity of artichokes during frozen storage. Inulin incorporation and IQF showed mutual positive effect on drip loss. Polyphenol oxidase (PPO) activity values fitted to 2nd order kinetic and the highest residuals were determined in static freezing. PPO showed alleviating effect on total phenolic content. Vacuum impregnation caused a color difference prior to freezing, but was found effective for maintaining color during storage. As a result, the use of quick freezing techniques together with the addition of cryoprotectant was effective in the preservation of artichoke quality attributes during frozen storage.

Quality and microstructure of tilapia fillets (Oreochromis niloticus) subjected to different freezing methods

The Nile tilapia (Oreochromis niloticus) fillets were frozen with static air (SA) at -20 °C, air blast freezing (AF) at -25 °C, combined method (CM - immersion in liquid nitrogen followed by AF) and cryogenic freezing (CF - immersion in liquid nitrogen). The effects of different freezing methods and of storage time at -18 °C (0, 30, 60 and 90 days) on fillet quality were evaluated. The temperature records were obtained, and the freezing times were determined by monitoring the temperatures of the geometric centers of the fillets. For CF, CM, AF and SA, the freezing times were 5.32, 127, 146 and 268 min, respectively. The quality of the frozen fillets was evaluated by measuring pH, volatile nitrogenous bases (TBV-N), thiobarbituric acid reactive substances (TBARS), and fatty acids and by obtaining a texture profile and performing scanning electron microscopy (SEM). The samples frozen by CF, after storage, had the highest levels of TBV-N because the high freezing rate produced superficial cracks that negatively affected the quality of the fillets. Freezing the samples with SA produced the worst quality indices and the microstructure was visibly damaged, with greater spaces between the fibers left by ice crystals. For all parameters evaluated, freezing with AF and CM resulted in fast freezing rates and better-quality tilapia fillets for 90 days of storage.

Agrochemical Spray Technology Adoption and Safety Awareness Assessment in Crop Protection in Vineyard Cultivation

A study was conducted in the Jalna district of Maharashtra to assess the adoption pattern of spray technology, and safety awareness among grape growers. The respondents were selected through random sampling and data was collected through a structured interview. The study revealed that among marginal landholders (&lt; 1 ha) back-pack type sprayer was mostly in operation with an adoption level of 75%. In small landholders (1-2 ha), horizontal triplex pump (HTP) sprayers with an adoption level of 51.85% followed by tractor-operated air-blast sprayers (40.75%) were prevalent pesticide spraying technologies. More than 2/3rd (76.00%) of medium landholders (2-4 ha) had adopted tractor-operated air blast sprayers. For the application of plant growth regulators, 62.5% of small farmers, 81.8% of medium, and 100% of farmers had adopted electrostatic sprayers. The number of chemical sprays per season varied from 25 to 100, making grapes one of the major pesticide-consuming crops. Capacity, efficiency, cost, and availability of sprayers on a custom hiring basis were the four major factors affecting the adoption of spraying technologies.

Evaluating spray drift from Uncrewed Aerial Spray Systems: A machine learning and variance-based sensitivity analysis of environmental and spray system parameters

Uncrewed Aerial Spray Systems (UASS), commonly called drones, have become an important application technique for plant protection products in Asia and worldwide. As such, environmental variables and spray system parameters influencing spray drift deserve detailed investigations. This study presents the data analysis of 114 UASS drift trials conducted between December 2021 and December 2022 in China. Study design was based on the ISO 22866:2005 protocol for spray drift trials and considered different UASS platforms, nozzles, and release heights, and specifically continuously measured weather conditions. The relative importance of the environmental variables and spray system parameters was evaluated by a random forest (RF) feature importance analysis, a Sobol sensitivity analysis and partial dependence plots. This approach was preferred to linear ranking techniques such as ANOVA (analysis of variance) due to the non-linearity of the system. In addition, partial dependence plots are proposed to visualize the relationship between specific input parameters within the system.Drift deposition curves calculated from the 114 trials show good agreement with previous UASS trials reported in the literature. As reported in previous studies, spray drift following UASS applications is lower than for manned aerial vehicles, greater than for ground spray applications, and similar to drift observed from orchard air blast applications. In addition, 9 trials were conducted on corn fields in order to evaluate the potential effect of crop cover on spray drift. Spray drift was observed to be reduced over the cropped soil, suggesting that plant cover might possibly reduce spray drift. These findings could help supporting drift mitigation policies, stewardship advice and product labelling around the world.

THE PROBLEM OF REGULATING FUNGICIDES ON THE SKIN SURFACE FOR OCCUPATIONAL SKIN DISEASE IN AGRICULTURAL WORKERS’ RISK PREDICTION

The aim. To establish the norms of fungicides on the skin surface and predicting the risk of occupational skin pathology in agricultural workers to develop measures to prevent diseases caused by dermal exposure to pesticides. Materials and methods. The natural experiment was performed in accordance with modern requirements (European Food Safety Authority (2022), and the risk assessment was carried out according to the Recommendations (Approved by the Ministry of Health of Ukraine No. 324 issued on 13.05.2009) with different methods of spraying techniques: rod, air blast fan spraying, pre-sowing, aviation, knapsack treatment. 17 series of natural experiments were performed, and the air of the working zone area (n =56) and dermal exposure (n =56) were analyzed for each worker with different pesticide application methods. Quantitative determination of pesticide content was carried out by gas-liquid and high-performance liquid chromatography methods. The results were statistically processed using a package of licensed statistical programs MedStat v.5.2 (Copyright © 2003-2019) and Microsoft® Excel® for Microsoft 365 MSO. Results. It was established that there is pesticide contamination, mainly of the gloves of tank filling operators when preparing working solutions. No contamination of the skin surface was detected; only pesticide residues were present on the surface of the workers’ overalls. A comparison of the exposure dose in case of percutaneous exposure during the performance of technological operations with different methods of processing, dermal equivalents of Acceptable Operator Exposure Level of pesticide to workers’ skin (DE AOEL) and the allowable dermal dose for professional contingents (ADderm) and the hazard coefficients by dermal exposure (HCderm) showed that that dermal exposure during individual technological operations with different processing methods had a reliable difference between processing methods, but there is no difference within one application method. Conclusions. During the comparison of the hazard coefficients for dermal exposure, calculated according to different models, no significant difference was found between the risks calculated according to DE AOEL and ADderm for individual technological operations in various treatment methods, except for the operator who performed knapsack treatment and the risk calculated according to ADderm is significantly lower compared to the DE AOEL risk.

IMPLEMENTATION OF COLD CHAIN SYSTEM IN PEELED DEVEINED TAIL-ON VANNAMEI SHRIMP (Litopenaeus vannamei) PRODUCTS

Vannamei (Litopenaeus vannamei) Peeled Deveined Tail-On (PDTO) shrimp is frozen shrimp product consumers highly preferred. However, shrimp products are easily perishable that require a proper cold chain system to preserve their quality, shelf life, and nutritional value. This study investigated the cold chain implementation of PDTO shrimp processing in the fishery industry. The temperature of shrimp products, water, and rooms was monitored during processing. Results showed that the shrimp temperature measured in each process was below 5°C. However, abusive temperatures were detected in water used in the peeling and deveining step and soaking process, while water and shrimp temperatures altered each other. Moreover, room temperatures were recorded under 20°C, conforming to Ministry of Marine and Fisheries regulations. Air Blast Freezer and cold storage temperatures revealed that ABF and CS could not meet the company’s temperature standards. These findings may help shrimp companies monitor steps indicating to have temperature abuse attentively.

Design and analysis of a 20-feet modular cold storage system

Cold storage plays an essential role in the cold supply chain, especially for fishery products. Compact cold storage systems that can be easily moved across various locations are attractive for archipelagic regions. This study aims to design and analyze a 20-ft modular cold storage system. The design stages include the development of a geometrical model, calculation of cooling load, and selection of a refrigeration machine. The analysis of the designed cold storage system was performed using transient computational fluid dynamic simulations using Ansys Fluent. The compact 20-ft cold storage design consists of three main rooms: the anteroom, air blast freezer room, and freezer storage room. The calculation results showed a maximum cooling load of about 6.6 kW occurring in the air blast freezer room at noon. According to the temperature distribution from the transient computational fluid dynamic simulation, each room had different cooling characteristics, with the highest cooling rate of 94.59 W/h in the air blast freezer room, achieving a targeted temperature of −40 °C in 5 h.

New approach for calculation of peak over pressure and impulse of aluminized explosive charges

ABSTRACT RDX/HMX-TNT-based aluminized explosive compositions have been investigated to find empirical relations based on heat of explosion (Q) and velocity of detonation (VOD) for calculation of peak over pressure (POP) and impulse (I). Four HMX-TNT-based aluminized compositions have been selected based on calculated values of Q and explosive power. Explosive charges of RDX/HMX-TNT-based aluminized compositions and TNT have been prepared by melt-cast technique for measurement of VOD and air blast. Cylindrical explosive charges with length to diameter ratio of ~ 1 and weight ~ 1.3 kg have been used for measurement of pressure-time profiles at standoff distance of 2–6 m. Similar measurements were also performed for the explosive charges of TNT of weight ~ 11 and 17 kg. Normalized values of Q and VOD 2 with corresponding values of TNT have been used to compute charge weight for calculation of scaled distance which is termed as normalized scaled distance. Form of empirical relations has been decided from variation of POP and I with normalized scaled distance. Values of constants used in these relations have been determined using regression analysis. Validation of empirical relations has been carried out by comparing calculated and experimental values of POP and I for explosive charges.