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Gas-powered jet nebulizers deliver medications to treat acute and chronic respiratory diseases. Several authors have found large variations in the performance of these nebulizers, and despite numerous attempts, deposition efficiency remains low for both adults and pediatrics. Using a Sympatec laser diffraction system and computational fluid dynamics (CFD) simulations with SolidWorks Flow Simulations and Ansys Fluent, this study uses a comparative analysis to explore the influence of supply air pressure, nozzle orifice diameter, and baffle geometry on jet nebulizer performance. Performance was quantified using critical performance metrics including vacuum levels driving aerosolization rate, Mass Median Aerodynamic Diameter (MMAD), and aerosolization time. Preliminary findings suggest that the authors' 2.54 mm wide, semi-conical bar baffle may produce superior vacuum levels, and surpasses the performance of the leading commercial bar baffle geometry, the SideStream, with a smaller MMAD (1.7 versus 2.3 microns). The study confirms the predicted relationship between supply pressure and nebulizer performance: higher pressure improves airflow rates, jet velocities, and aerosol characteristics, and reduces aerosolization times. Additionally, a larger nozzle orifice diameter increases airflow rates and promotes better aerosol characteristics, highlighting a direct correlation between orifice size and nebulizer performance. This work underscores the importance of expanding research in nebulizer performance beyond the traditional focus on testing paired nebulizer/compressor systems. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

One of the major infectious routes of respiratory diseases, such as COVID-19, is exposure to viral aerosols transmitted from an infected person over a short distance. Conventionally, plastic shields or personalized ventilation methods utilizing fans or jets to generate airflows between two facing users have been used to combat such short-range infection. Nevertheless, these methods entail several drawbacks: bulky apparatus hindering users' cooperative activities must be placed between them, the shields need frequent cleaning and block conversation voices, and the jet- or fan-based methods yield uncomfortably strong airflows hitting the user's face. Here, a new airflow-based strategy for suppressing aerosol exposure, which overcomes all the above inconveniences, was proposed. In this strategy, ultrasound-driven localized airflows called acoustic streaming, whose positions and traveling directions can be electronically controlled, was used. A prototype system composed of a group of phased arrays of airborne ultrasound transducers was created, and they were set behind the users to redirect paths of aerosols emitted from the user's mouth toward their upper and back sides. It is experimentally confirmed that the proposed system could reduce exposure to aerosols whose diameters are the same as ones emitted from people by 89.95% under a certain setup. By controlling the position and direction of the streaming, the proposed method can maintain its performance when users move their heads or bodies. The proposed system can virtually produce or delete programmable partitions in the air as desired, and can be integrated with other conventional methods for infection control. [ABSTRACT FROM AUTHOR]

To design and operate various equipment of the solids control system in offshore drilling platforms, it is important to establish how the moisture content influences the characteristics of drilled cuttings to form packed beds and flow over solid surfaces. The current study comprehensively analyzes how moisture content, primarily composed of water and representing waterbased muds (WBMs), influences the bed packing properties and drilled cuttings' flowability. The particle aggregation/disaggregation dynamics, loose and tapped bulk densities and porosities, compaction dynamics of packed beds, Hausner ratio, and angle of repose of drilled cuttings with ten distinct moisture contents (1.4--44.0 wt%) were analyzed. It was noticed that the increment of moisture content up to 15.2% promoted the formation of looser interparticle structures. However, these structures were steadier, showing greater difficulty flowing and releasing air/liquid. The continuous increment of moisture content beyond 15.2% promoted a complete change in the material behavior. The interparticle structures became denser. The material could flow and release air/liquid more easily. In addition, it was possible to establish a classification of the different behaviors of drilled cuttings according to the moisture content. Predictive models were proposed to describe the influence of the moisture content on the bed packing and flowability properties of drilled cuttings. [ABSTRACT FROM AUTHOR]

Coronaviruses being capable of spreading through droplet contamination have raised significant concerns regarding high-capacity public rail transport, such as the metro. Within a rapidly moving railcar cabin, the internal airflow lags behind the bulkhead, generating internally induced airflow that accelerates droplet dispersion within a non-inertial reference system. This study investigates the impact of acceleration on the diffusion of cough droplets of varying sizes using computational fluid dynamics. The modified k–ε equation in ANSYS® Fluent was utilized to simulate droplet diffusion under different body orientations by adjusting the inertial force correction source term. Results indicate that droplets in the middle size range (50–175 μm) are primarily influenced by inertial forces, whereas smaller droplets (3.5–20 μm) are predominantly controlled by air drag forces. Regardless of facial orientation, the outlet of high-capacity public rail transport poses the highest risk of infection. [ABSTRACT FROM AUTHOR]

When the lightweight quartz fiber-reinforced phenolic (LQFRP) composite is subjected to the combined effect of a local structural heat source and high-speed airflow, its ablation behavior exhibits significant localized characteristics and strong coupled effect. In this study, we have developed a bidirectional loosely coupled numerical model that integrates thermal, fluid, solid and ablation phenomena to solve the ablation-through problem of the LQFRP composite. The model takes into account the mechanisms of pyrolysis, oxidation, sublimation, and thermal mechanical erosion that occur during the ablation process of the LQFRP composite. The results suggest that the local structural heat source plays a crucial role in the erosion and retreat of the LQFRP composite. The morphology of the ablation pit shows a noticeable asymmetry, which is attributed to the aerodynamic heat and force. As a result of the local structural heat source, the fluid temperature downstream of the ablation pit is higher compared to that upstream of the ablation pit. The fluid that flows downstream of the ablation pit undergoes significant compression, leading to the formation of an oblique shock wave. The distribution of resin pyrolysis degree within the LQFRP composite is influenced by internal heat conduction. This study will offer valuable insights and guidance for the practical application of the LQFRP composite in the ultra-high temperature field. [ABSTRACT FROM AUTHOR]

The archerfish is unique in its ability to hunt by shooting a jet of water from its mouth that hits insects situated above the water's surface. To aim accurately, the fish needs to overcome physical factors including changes in light refraction at the air-water interface. Nevertheless, archerfish can still hit the target with a high success rate under changing conditions. One possible explanation for this extraordinary ability is that it is learned by trial and error through a motor adaptation process. We tested this possibility by characterizing the ability of the archerfish to adapt to perturbations in the environment to make appropriate adjustments to its shots. We introduced a perturbing airflow above the water tank of the archerfish trained to shoot at a target. For each trial shot, we measured the error, i.e., the distance between the center of the target and the center of the water jet produced by the fish. Immediately after the airflow perturbation, there was an increase in shot error. Then, over the course of several trials, the error was reduced and eventually plateaued. After the removal of the perturbation, there was an aftereffect, where the error was in the opposite direction but washed out after several trials. These results indicate that archerfish can adapt to the airflow perturbation. Testing the fish with two opposite airflow directions indicated that adaptation took place within an egocentric frame of reference. These results thus suggest that the archerfish is capable of motor adaptation, as indicated by data showing that the fish produced motor commands that anticipated the perturbation. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of diclofenac, an anti-inflammatory drug, was investigated with TiO2 photocatalyst under UV light (365nm). The effects of photocatalyst concentrations (0.5 g/L, 1 g/L and 2 g/L) and air flow rates (3L/h, 6 L/h, 12 L/h and 18 L/h) on photodegradation kinetic were evaluated for 15 mg/L diclofenac solution during 4 hours. The results showed that the amount of TiO2 and air flow rates have direct influence on the photocatalytic degradation of diclofenac. Excessive catalyst amount and high air flow rates inhibited the degradation of diclofenac. The highest diclofenac degradation efficiency of 78.4 % were achieved by 6 L/h air flow rate with a photocatalyst concentration of 0.5 g/L. The photocatalytic degradation of diclofenac followed the Langmuir-Hinshelwood kinetic model except the experiments carried without air flow and very low air flow rates. [ABSTRACT FROM AUTHOR]

Excellent mechanical and electric properties enable the piezoelectric materials to be widely and dynamic aero-mechanical-electric coupling properties of the piezoelectric plate structures can significantly affect performance of aircrafts flying in high speed. This paper is focused on the flutter behaviors of the functionally graded piezoelectric material (FGPM) plate in supersonic airflow. The first-order shear deformation theory (FSDT) is employed to formulate the energy functional of the FGPM plate with general boundary conditions. The supersonic air flow is taken into account using the supersonic piston theory. The governing equations for the aero-mechanical-electric coupling system are deduced on basis of the Hamilton's principle. To address the limitation of intricate boundary conditions to the admissible functions, a modified Fourier series is introduced to yield the unified solutions of the FGPM plate subject to supersonic airflow and with arbitrary boundary conditions. Flutter properties of series of FGPM plates are investigated to demonstrate robust ability of the proposed method to accurately yet consistency include the aero-elastic-electric coupling, inhomogeneous material and arbitrary boundary conditions. The influences of the boundary condition, material constituent, external voltage and yawed flow angle on the vibration, and flutter behaviors of the FGPM plate are examined. Adjusting corresponding parameters accordingly can significantly improve the stability of the plate structures subject to supersonic airflow, which provides physical insights into dynamic optimal design of the plate structures. [ABSTRACT FROM AUTHOR]

Dust resuspension from four typical fabrics (cotton, linen, silk, and polyester) exposed to airflow with common velocities within 0–10 m/s, including a moving fabric case and a fixed fabric case, was experimentally studied in this article. A set of empirical correlations, involving air velocity, fabric motion mode, fabric type, and airflow duration was developed to describe and predict the moving fabric case. It was found that a stronger-than-expected resuspension was triggered by short-term accelerating airflow. The resuspension enhancement of over 90% was reported for the moving fabrics compared with the fixed ones. Fabric motion induced by airflow was proposed to account for these resuspension findings. Fabric acceleration was then demonstrated to be a key factor in evaluating the resuspension for such a scenario. This article not only reveals an inconspicuous phenomenon of dust resuspension from fabrics under the impact of airflow and consequent fabric motion, but also provides a theoretical basis for particulate matter assessment and regulation. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

To provide reference for the design of the air-suction tea sorting device, the coupled numerical simulation model was established by the coupling method of computational fluid dynamics (CFD) and discrete element method (DEM) with tea of different quality as test objects, and the model was verified experimentally. Regarding tea particles of different quality, when the test tea particle mass was 0.215, the test value was located in the simulation value with a minimum error of 9 mm, which an error rate of 3.33%, and maximum error of 19 mm, with an error rate of 7.03%. When the test tea particle mass was 0.145, the minimum error of the test value was 5 mm and the error rate was 1.54%, and the maximum error was 9 mm and the error rate was 3.33%. The verification results established the accuracy of the model. During the suspension test and simulation, tea particles were affected by the air flow field of the observation tube, and tea particles fluctuated. During suspension, tea particles were attached to the inner wall of the observation tube under the action of the air flow field. An in-depth study showed that the relationship between the different distances from the initial position of the particles during suspension and the simulation time was a peak function. The extreme function is used to fit the actual trajectory, and the fitting degree is good. The fitting degree of the particle closest to the initial position was 0.9455, and the fitting degree of the particle farthest from the initial position was 0.9981. [ABSTRACT FROM AUTHOR]

The airport line plays an important role in the airport landside traffic connection, which greatly relieves the urban road pressure. Studying the characteristics and laws of the time and space distribution of the airport line passenger flow will provide basic support for the airport line's capacity configuration, passenger flow control, and air‐track coordinated operation, and will also provide quantitative basis for the layout of urban terminal buildings. This paper proposes a method to analyse the temporal and spatial distribution characteristics of airport line passenger flow based on AFC card swiping data. By mining and extracting the travel behaviour data of subway airport line air passengers, the distribution characteristics of airport line passenger flow are analysed and visualized from two aspects of passenger travel time and space. Finally, a case study is carried out based on the actual data of Daxing airport express. The results show that: (1) the travel time of departure and return passengers is concentrated in 60–90 min; (2) The departure and arrival points of passengers are concentrated within the Fourth Ring Road, and a large number of air passenger flows are gathered and evacuated at hubs such as Beijing South Railway Station and Beijing West Railway Station. [ABSTRACT FROM AUTHOR]

An air-based photovoltaic thermal collector (PVTC) is a system that generates both electricity and heat using air flowing over a photovoltaic (PV) module. This system offers the advantage of easy maintenance; however, it suffers from lower thermal efficiency compared to other PVTCs, mostly owing to the low heat capacity of air. Thus, this study introduces a novel PVTC incorporating dual ducts and semicircular turbulators, which were experimentally evaluated under actual weather conditions in the Republic of Korea. The proposed PVTC was compared with two other types of PVTC: one is a single-duct PVTC with semicircular turbulators, and the other is a dual-duct PVTC without turbulators. The results showed that the thermal efficiency of the proposed PVTC increased by approximately 88.7% compared to the single-duct PVTC with a turbulator and by 9.3% compared to the dual-duct PVTC without a turbulator. The electrical efficiency showed a slight decrease of about 7.2% compared to the single-duct PVTC but an increase of 1.4% compared to the dual-duct PVTC without a turbulator. Overall, the total efficiency of the proposed PVTC increased by 54.2% and 7.7% compared to the single-duct PVTC and the dual-duct PVTC without a turbulator, respectively. These experimental results demonstrate that attaching dual ducts and semicircular turbulators to an existing PVTC increases the daily thermal energy output, which ultimately enhances the total daily energy output. [ABSTRACT FROM AUTHOR]

Achieving a quick temperature increase is a burning issue for biophysical applications, like germ inactivation and tumor ablation, and for energy performances, like solar collectors and steam generators. Based on the plasmon resonance phenomenon, noble metallic nanoparticles have emerged as promising weapons due to their very high biocompatibility, optical properties, and high surface-to-volume ratio, increasing energy conversion and allowing the maximum temperature to be reached faster. This work examines the energy conversion in sandwiched glassy platforms with gold nanorods. The platforms are kept vertically in the air and illuminated by a 0.5 W near-infrared laser (808 nm). To describe this aspect theoretically, the size and conversion efficiency of the electromagnetic properties are compromised between the proposed model and the stability of the nanorods. As a research approach, our model of cross-sections and polarizability for the surface effect is proposed, coupled with classical CFD numerical calculations. The results of the proposed model, validated by a thermal camera and spectroscopy measurements, indicate that as long as the energy conversion is visible with relatively low-power lasers (ΔT = 18.5 °C), the platforms do not offer fast heat dissipation. The results indicate that, despite the flow forcing by the air inflow, the entropy generation due to heat conduction is more than three orders higher than the dynamic entropy production. Flow forcing corresponds to the value of the velocity for classical convective motions. Therefore, the delivered heat flux must be distributed via convective transport or the associated high-conductive materials. [ABSTRACT FROM AUTHOR]

The mechanisms underlying bat and bird activity peaks (attraction) or losses (avoidance) near wind turbines remain unknown. Yet, understanding them would be a major lever to limit the resulting habitat loss and fatalities. Given that bat activity is strongly related to airflows, we hypothesized that airflow disturbances generated leeward (downwind) of operating wind turbines–via the so-called wake effect–make this area less favorable for bats, due to increased flight costs, decreased maneuverability and possibly lower prey abundance. To test this hypothesis, we quantified Pipistrellus pipistrellus activity acoustically at 361 site-nights in western France in June on a longitudinal distance gradient from the wind turbine and on a circular azimuth gradient of wind incidence angle, calculated from the prevailing wind direction of the night. We show that P. pipistrellus avoid the wake area, as less activity was detected leeward of turbines than windward (upwind) at relatively moderate and high wind speeds. Furthermore, we found that P. pipistrellus response to wind turbine (attraction and avoidance) depended on the angle from the wake area. These findings are consistent with the hypothesis that changes in airflows around operating wind turbines can strongly impact the way bats use habitats up to at least 1500 m from the turbines, and thus should prompt the consideration of prevailing winds in wind energy planning. Based on the evidence we present here, we strongly recommend avoiding configurations involving the installation of a turbine between the origin of prevailing winds and important habitats for bats, such as hedgerows, water or woodlands. [ABSTRACT FROM AUTHOR]

To study the characteristics of nasal airflow in the presence of nasal cycle by computational fluid dynamics. CT scan data of a healthy Chinese individual was used to construct a three-dimensional model of the nasal cavity to be used as simulation domain. A sinusoidal airflow velocity is set at the nasal cavity entrance to reproduce the breathing pattern of a healthy human. There was a significant difference in the cross-sectional area between the two sides of the nasal cavity. Particularly, the decongested side is characterized by a larger cross-section area, and consequently, by a larger volume with respect to the congested side. The airflow velocity, pressure, and nasal resistance were higher on the congested narrow side. The temperature regulation ability on the congested narrow side was stronger than that on the decongested wider side. During the nasal cycle, there are differences in the nasal cavity function between the congested and decongested sides. Therefore, when evaluating the impact of various factors on nasal cavity function, the nasal cycle should be considered. [ABSTRACT FROM AUTHOR]

For people with respiratory disorders who need additional oxygen therapy, oxygen concentrators are vital medical equipment. By concentrating oxygen from the ambient air, they function to give the user a greater flow of oxygen-enriched air. The application of lithium zeolite for oxygen concentration in POCs is the most intense part of this work. One kind of zeolite material that may selectively absorb nitrogen from the air to increase oxygen concentration is lithium zeolite. The capacity, effectiveness, and dependability of a POC fitted with lithium zeolite are all examined in this study, along with its overall performance. The findings show that lithium zeolite, which has benefits including high oxygen purity and low energy consumption, is a potential material for use in POCs. The results of this study aid in the creation of POCs for oxygen therapy that are more effective and efficient. This study suggests utilizing an Arduino microcontroller and an HX710B air pressure sensor to measure the oxygen flow rate in a POC. The POC's oxygen flow channel incorporates the HX710B sensor to monitor pressure variations, which the Arduino uses to translate into flow rate readings. To verify the accuracy and dependability of the system, its performance is assessed under different flow rate scenarios. Lithium zeolites are well-known for having a high selectivity for nitrogen adsorption, which can enhance the concentrator's oxygen separation process's effectiveness. Lithium-zeolite-based oxygen concentrators may have a lower environmental effect than standard concentrators. [ABSTRACT FROM AUTHOR]

Among all the operating parameters that control the cell culture environment inside bioreactors, appropriate mixing and aeration are crucial to ensure sufficient oxygen supply, homogeneous mixing, and CO 2 stripping. A model-based manufacturing facility fit approach was applied to define agitation and bottom air flow rates during the process scale-up from laboratory to manufacturing, of which computational fluid dynamics (CFD) was the core modeling tool. The realizable k -ε turbulent dispersed Eulerian gas-liquid flow model was established and validated using experimental values for the volumetric oxygen transfer coefficient (k L a). Model validation defined the process operating parameter ranges for application of the model, identified mixing issues (e.g., impeller flooding, dissolved oxygen gradients, etc.) and the impact of antifoam on k L a. Using the CFD simulation results as inputs to the models for oxygen demand, gas entrance velocity, and CO 2 stripping aided in the design of the agitation and bottom air flow rates needed to meet cellular oxygen demand, control CO 2 levels, mitigate risks for cell damage due to shear, foaming, as well as fire hazards due to high O 2 levels in the bioreactor gas outlet. The recommended operating conditions led to the completion of five manufacturing runs with a 100% success rate. This model-based approach achieved a seamless scale-up and reduced the required number of at-scale development batches, resulting in cost and time savings of a cell culture commercialization process. [Display omitted] • Appling a bioprocessing model package in manufacturing facility fit. • Predicting impeller flooding of a scale-up model by computational fluid dynamics. • Predicting pCO2 levels by CO 2 stripping model. • Evaluating cellular oxygen demand, foaming, and fire hazards. • Achieving seamless scale-up with reduced manufacturing scale development batches. [ABSTRACT FROM AUTHOR]

Due to its superior insulating qualities, SF6 gas is extensively used in the power sector. However, because of its poor environmental protection properties, finding ecologically acceptable insulating gas has become a critical challenge in the power sector in the context of pursuing green electricity. This work simulates the arc-quenching performance of a gas mixture of CF3I and CO2, which is thought to be a workable substitute for SF6 gas. The COMSOL software is used to build a two-dimensional model of a single-pipe arc-quenching chamber based on the concepts of magnetohydrodynamics (MHD) theory. The lightning impulse current is made by applying electrical stimulation to pure CO2 gas, gas mixtures with 10% CF3I and 90% CO2, and gas mixtures with 30% CF3I and 70% CO2 in the single-pipe arc-quenching chamber. During the first stage of arc formation, the results show that CF3I/CO2 gas mixtures with 10% and 30% CF3I have lower electrical conductivity than pure CO2 gas. An 8/20 μs lightning impulse current waveform with a magnitude of 4 kA is used for this observation. The highest airflow velocity for pure CO2 is 1744 m/s, but the mixture of 10%/90% CF3I/CO2 has a maximum airflow velocity of 1593 m/s. The 30%/70% CF3I/CO2 mixture has the highest maximum airflow velocity at 1840 m/s. Airflow velocity increases and the overpressure in the arc-quenching chamber is prolonged when there is a greater concentration of CF3I gas in the gas mixture. Consequently, these factors greatly reduce the duration of the arc-extinguishing time. The arc-quenching chamber's overpressure is extended when the amount of CF3I gas in the gas mixture is increased, which increases the velocity of the airflow. As a result, these factors significantly decrease the duration of the arc-extinguishing time. [ABSTRACT FROM AUTHOR]

Accurate air traffic flow prediction assists controllers formulate control strategies in advance and alleviate air traffic congestion, which is important to flight safety. While existing works have made significant efforts in exploring the high dynamics and heterogeneous interactions of historical air traffic flow, two key challenges still remain. (1) The transfer patterns of air traffic are intricate, subject to numerous constraints and limitations such as controllers, flight regulations, and other regulatory factors. Relying solely on mining historical traffic evolution patterns makes it difficult to accurately predict the constrained air traffic flow. (2) Weather conditions exert a substantial influence on air traffic, making it exceptionally difficult to simulate the impact of external factors (such as thunderstorms) on the evolution of air traffic flow patterns. To address these two challenges, we propose a Spatiotemporal Knowledge Distillation Network (ST-KDN) for air traffic flow prediction. Firstly, recognizing the inherent future insights embedded within flight plans, we develop a "teacher-student" distillation model. This model leverages the prior knowledge of upstream-downstream migration patterns and future air traffic trends inherent in flight plans. Subsequently, to model the influence of external factors and predict air traffic flow disturbed by thunderstorm weather, we propose a student network based on the "parallel-fusion" structure. Finally, employing a feature-based knowledge distillation approach to integrate prior knowledge from flight plans and extract meteorological features, our method can accurately capture complex and constrained spatiotemporal dependencies in air traffic and explicitly model the impact of weather on air traffic flow. Experimental results on real-world flight data demonstrate that our method can achieve better prediction performance than other state-of-the-art comparison methods, and the advantages of the proposed method are particularly prominent in modeling the complicated transfer pattern of air traffic and inferring nonrecurrent flow patterns. [ABSTRACT FROM AUTHOR]

Positive pressure ventilators (PPV) used by 97.7% of officers of the National Fire Service in Poland, are characterized by work that is not in line with the expectations of the firefighters. In order to improve the technical and operational features of these devices, a survey was conducted among 25,000 eligible firefighters, identifying the application of these devices, problems in use and expected development directions. A total of 682 officers voluntarily completed the survey. Based on their findings, it was determined that ventilators are most often used to smoke out buildings after or during a fire. Mentioned problems when using these devices were mainly noise (78.2%), exhaust emissions (68.5%), and impediments to mobility through the device's relatively heavy weight (40.2%). Other inconveniences were mentioned by less than 20% of firefighters. Polish firefighters expect the development of these devices mainly in terms of the above-mentioned features (noise reduction (81.7%) and reduction of the weight and size of the ventilators (about 50%)). Other expectations relate to the improvement of smoke removal in buildings: increasing the efficiency of smoke removal (46.4%) and efficiency regarding the rate of smoke removal in a building by increasing the size of the incoming airflow from the building's surroundings (33.2%). About 15% of firefighters expect changes in the operation of the ventilator itself, that is, an increase in the effective operating time (electric ventilators) and an increase in the device's uptime. The aim of the article is to identify the issues encountered during the operation and to indicate the expected direction of development for PPV by users. This information can be used by engineers to initiate new development work on these devices. [ABSTRACT FROM AUTHOR]

The gearbox seal system is a critical component of the electrical multiple units drive system, with a direct impact on the safety and reliability of train operations. This study intends to analyze how structural parameters of the gearbox seal system influence the seal performance from the viewpoint of "oil–air separation and scavenge oil" by using a discrete phase model and volume of fluid. The results show that the oil–air separation performance is mainly affected by the oil droplets' inertia force and the airflow traction force, and the scavenge oil performance is decided by the oil–air separation performance of each seal chamber. The relationships between seal chamber size, axial seal clearance width, height difference, scavenge oil hole diameter, and seal performance are analyzed, and the study also found that optimizing the stator chamber depth–width ratio of the seal system studied in this paper at 2.5, reducing the rotor chamber depth–width ratio and axial seal clearance width, and increasing the relative height difference can improve the seal performance. And increasing the scavenge oil hole diameter also enhances the seal system's performance. The simulation results can be used as design references for gearbox seal systems. [ABSTRACT FROM AUTHOR]

This paper aims to explore machine learning techniques for post‐processing high‐resolution Numerical Weather Prediction (NWP) products for the early detection of convection. Data from the Arome Ensemble Prediction System and satellite observations from the Rapidly Developing Thunderstorm (RDT) product by Météo‐France are used to train a recurrent neural network model to predict areas of total convection and moderate convection. The learning task is formulated as a binary classification problem using a long short‐term memory (LSTM) network architecture. Results from the LSTM model are compared with an object‐based probabilistic approach to forecast convection using metrics such as a receiver operating characteristics (ROC) curve, the Brier score and reliability. Results indicate that the LSTM model performs similarly to the object‐based probabilistic benchmark when classifying moderate convection areas and shows improved skill when classifying areas of total convective. Finally, the LSTM model results are presented within an air traffic management context to showcase the potential use of machine learning models within an operational application. [ABSTRACT FROM AUTHOR]

Understanding the characteristics of coal spontaneous combustion (CSC) in goaf under different porosities is crucial for comprehending the mechanism of CSC and its prevention and control. In this paper, a multi-field coupled model of CSC in the goaf, considering porosity variation, is developed to investigate the effect of porosity on the CSC characteristics in the goaf. The results indicate that, as the goaf depth increases, both porosity and permeability decrease. When the highest goaf porosity is 25%, the average airflow velocity is between 0.00134 and 0.00139 m/s. In contrast, the average airflow velocity in the goaf with a porosity of 40% is approximately six times greater than that of the goaf with a porosity of 25%. As the goaf porosity increases, the overall oxygen concentration, temperature, and oxidized zone area also rise. Moreover, the oxidation zone area can be quantified and visualized, thereby enabling more effective prediction of the CSC risk in the goaf. The findings of the study have a positive significance in guiding the prevention and control of coal fires. [ABSTRACT FROM AUTHOR]

The effect of the mainline slope on the ceiling temperature profile in a branched tunnel has not been clarified nor included in existing models. Thus, in this paper, the numerical code was employed to investigate the induced airflow velocity and gas temperature beneath the ceiling in a branch tunnel with a sloped upstream mainline. The mainline slope varied from 1% to 7%, with an interval of 1%. Five fire power of 3 MW, 5 MW, 10 MW, 15 MW, and 20 MW are employed on each slope. The airflow velocity and the longitudinal temperature in the mainline tunnel are measured and analyzed. Results show that the stack effect obviously occurred, which caused longitudinal velocity to prevent the smoke reverse flow in the mainline. The induced airflow velocity in the upstream inclined mainline is higher with increasing slope, and the dimensionless velocity is normalized well by the proposed expression. The maximum ceiling temperature is independent of the mainline slope and correlated well by Q*2/3, but the effect of the mainline slope on temperature longitudinal decay is worth considering. Finally, a normalized expression for longitudinal temperature decay in an inclined mainline is proposed by taking the fire power and mainline slope into account. [ABSTRACT FROM AUTHOR]

Nonequilibrium flows of air components behind reflected shock waves are systematically studied on the basis of several theoretical models for the rate coefficients of fully coupled vibrational energy exchanges and chemical reactions. Numerical simulations are performed in the frame of the state-to-state approach under initial conditions corresponding to recent shock-tube experiments in mixtures O 2 /Ar, NO/Ar, NO/N 2 /Ar. The model takes into account partial vibrational relaxation between the incident and reflected shock waves, state-resolved dissociation, recombination, exchange reactions with formation of NO in the vibrationally excited states, as well as vibrational–vibrational and vibrational–translational energy transitions. It is shown that for oxygen, relaxation between the incident and reflected shocks is not frozen, and taking it into account in the most test cases considerably improves the agreement of calculated and experimentally measured pressure. For NO-containing mixtures, the effect of intermediate relaxation is weaker. Average deviation of the number density of molecular species with respect to the experimental one is analyzed for several hundreds of numerical simulations; on the basis of these estimates, recommendations are given for the best choice of model parameters. These recommendations can be used for modeling high-temperature flows, in particular, under reentry conditions. • Recent shock-tube experiments in air species are simulated numerically. • State-to-state models of vibrational–chemical coupling are validated. • Good agreement with experimental data is shown. • Recommendations are given for the best choice of model parameters. [ABSTRACT FROM AUTHOR]

Wind machines based on the air disturbance method are progressively employed to mitigate frost damage within the agricultural machinery frost protection. These devices are utilized during radiative frost nights to disrupt near-surface thermal inversion through air mixing. Despite this application, the fundamental mechanisms underlying these mixing processes are not well comprehended. In this research, numerical simulations were conducted using COMSOL Multiphysics software version 6.0 to simulate the flow and heat transfer processes between the thermal airflow and both the tea canopy and stems. The results indicated that due to obstruction from the canopy cross-section, the airflow velocity on the contact surface rapidly increased. As the airflow further progressed, the high-speed region of the airflow gradually approached the canopy surface. Turbulent kinetic energy increased initially on the windward side of the canopy cross-section and near the top interface. On the windward side of the canopy, due to the initial impact of the thermal airflow, rapid heating occurred, resulting in a noticeable temperature difference between the windward and leeward sides within a short period. In the interaction between airflow and stems, with increasing airflow velocity, fluctuations and the shedding of wake occurred on the leeward side of the stems. The maximum sensible heat flux at the windward vertex of the stem increased significantly with airflow velocity. At an airflow velocity of 2.0 m/s, the maximum heat flux value was 2.37 times that of an airflow velocity of 1.0 m/s. This research utilized simulation methods to study the interaction between airflow and tea canopy and stems in frost protection, laying the foundation for further research on the energy distribution in tea ecosystem under the disturbance of airflow for frost protection. [ABSTRACT FROM AUTHOR]

The two-phase countercurrent flow limitation (CCFL) in horizontal channels is important in relation to nuclear reactor safety. In this study, we aim to investigate the CCFL characteristics and the flow behaviors in horizontal circular pipes with small diameters. The effects of pipe diameter and the water head in the upper plenum on CCFL characteristics are experimentally studied. An image-processing technique and statistical treatments are implemented to analyze the horizontal countercurrent flow. The results show that the CCFL characteristics for the horizontal circular pipes with small diameters can be well correlated using the dimensionless parameters, which are based on adding fluid viscosity to the Wallis parameters. The CCFL characteristics are significantly affected by the pipe diameter and are slightly affected by the water head above the horizontal pipe. The gas–liquid interface fluctuates with certain periods, and flow pattern transitions happen in the horizontal air–water countercurrent flow. As the air flow rate increases, the occurrence location of the liquid slug appears to shift towards the water entrance. In addition, the further away from the water entrance, the lower the average of liquid holdup. [ABSTRACT FROM AUTHOR]

TiO2 was loaded on the porous nickel foam from the suspended ethanol solution and used for the photocatalytic removal of NOx. Such prepared material was heat-treated at various temperatures (400–600 °C) to increase the adhesion of TiO2 with the support. Obtained TiO2/nickel foam samples were characterized by XRD, UV–Vis/DR, FTIR, XPS, AFM, SEM, and nitrogen adsorption at 77 K. Photocatalytic tests of NO abatement were performed in the rectangular shape quartz reactor, irradiated from the top by UV LED light with an intensity of 10 W/m2. For these studies, a laminar flow of NO in the air (1 ppm) was applied under a relative humidity of 50% and a temperature of 28 °C. Concentrations of both NO and NO2 were monitored by a chemiluminescence NO analyzer. The adsorption of nitrogen species on the TiO2 surface was determined by FTIR spectroscopy. Performed studies revealed that increased temperature of heat treatment improves adhesion of TiO2 to the nickel foam substrate, decreases surface porosity, and causes removal of hydroxyl and alcohol groups from the titania surface. The less hydroxylated surface of TiO2 is more vulnerable to the adsorption of NO2 species, whereas the presence of OH groups on TiO2 enhances the adsorption of nitrate ions. Adsorbed nitrate species upon UV irradiation and moisture undergo photolysis to NO2. As a consequence, NO2 is released into the atmosphere, and the efficiency of NOx removal is decreasing. Photocatalytic conversion of NO to NO2 was higher for the sample heated at 400 °C than for that at 600 °C, although coverage of nickel foam by TiO2 was lower for the former one. It is stated that the presence of titania defects (Ti3+) at low temperatures of its heating enhances the adsorption of hydroxyl groups and the formation of hydroxyl radicals, which take part in NO oxidation. Contrary to that, the presence of titania defects in TiO2 through the formation of ilmenite structure (NiTiO3) in TiO2/nickel foam heated at 600 °C inhibits its photocatalytic activity. No less, the sample obtained at 600 °C indicated the highest abatement of NOx due to the high and stable adsorption of NO2 species on its surface. [ABSTRACT FROM AUTHOR]

This present investigation unveils a novel insight into the dominant airmass flows originating from both continental and maritime sources, shaping the characteristics of the raindrop size distribution (DSD), atmospheric instabilities, and cloud effective radius over Delhi (28.62°N, 77.17°E), the capital city of India. The investigation employs the Hybrid Single-Particle Lagrangian Integrated Trajectory model to analyze airmass back trajectories corresponding to days featuring rain events within the study area. An observable pattern emerges: days with rainfall driven by continental (maritime) activities experience higher (lower) atmospheric instabilities, which is validated by radiosonde measurements. This enhanced atmospheric instability leads to the prevalence of larger raindrops during continental-influenced rain events, in contrast to days marked by maritime airflow, as estimated from surface-based disdrometer measurements. Furthermore, observations from the INSAT 3D/3DR satellite indicate a tendency towards a smaller cloud effective radius associated with continental airmass inflow, as opposed to maritime inflow. Notably, a category of rain events characterized by ambiguous airmass back trajectories, referred to as mixed types, is identified. These mixed events showcase intermediary variations in the investigated atmospheric parameters, positioning them between the continental and maritime scenarios. The discernible differences in DSD characteristics between rain events influenced by continental and maritime activities yield fluctuations in the radar reflectivity-rain rate (Z-R) power law relations, which bear significance for the application of rain radar remote sensing. Hence, this investigation underscores the critical implication of incorporating airmass source information while characterizing rain features and related atmospheric parameters over a capital metropolis like Delhi. [ABSTRACT FROM AUTHOR]

The energy harnessing from flow-induced vibrations (FIV) by an oscillating foil placed tandemly behind a circular cylinder (which serves as a vortex generator) is investigated. The foil is submerged in the wake produced by the fixed cylinder and could oscillate in the direction perpendicular to the incoming flow with single-degree freedom. The spacing ratio ranges from 1.0 to 5.0. The oncoming fluid velocity is U = 1–10 m/s, corresponding to the reduced velocity Ur = 3.81–38.08 and the Reynolds number Re = 9.58 × 103–9.58 × 104. Four harnessing damping ratios (ζharness = 0.0054–0.0216) are used to simulate the energy conversion conditions. The main conclusions are: (1) The optimal oscillation pattern related to the highest harnessed energy emerges as the spacing ratio close to 1.0. (2) The airflow energy converted by the foil is positively correlated with the harnessing damping ratio because the amplitude responses are similar at various harnessing damping ratios. A high velocity yields the highest harnessed power. (3) The harnessing efficiency of the foil could reach 48.89%, which is much more than that of an isolated flapping foil. [ABSTRACT FROM AUTHOR]

In this study, the fluorescence properties of Lumisis, a phosphor that can be easily applied to ultrafine wires, were evaluated. By evaluating the wavelength characteristics of Lumisis phosphor, we investigated the possibility of applying it to a dual-wavelength laser-induced fluorescence (LIF) measurement system and evaluated the accuracy of temperature measurements. The difference between the decrease in the percentage intensities of the red and green fluorescence of Lumisis phosphors showed that two-color LIF was possible. The Lumisis phosphor–mixture ratio was optimized as 1:1.25, and the average measurement error of the fluorescent wire was 0.20 K, as evaluated through uncertainty analysis. Finally, the application of this measurement method to hot air jet phenomena showed that this method accurately captures the temperature changes in hot air, thus proving its validity. [ABSTRACT FROM AUTHOR]

Heat dissipation performance is crucial for the operational reliability of industrial equipment, which can be monitored by detecting the wind or airflow temperature of the radiator. The emergence of triboelectric nanogenerators (TENGs) provides new routes for wind energy harvesting and self‐powered sensing. Herein, a rotary wind‐driven triboelectric nanogenerator (RW‐TENG) with soft‐contact working mode is newly designed to achieve tunable contact areas by utilizing the reliable thermal response of NiTi shape memory alloy (SMA) to air/wind temperature. The RW‐TENG can generate different triboelectric outputs under air stimulation with different speeds or temperatures, which is demonstrated as a power source for online monitoring sensors, self‐powered wind speed sensing, and airflow temperature monitoring. Specifically, a self‐powered sensor of wind speed is demonstrated with a sensitivity of 0.526 µA m−1 s between 2.2 and 19.6 m s−1, and a self‐powered monitoring device of high airflow temperature, which show relatively short response time (109 s), strong anti‐interference ability and outstanding long‐term durability. This study introduces an innovative route for real‐time detection of airflow temperature in wind‐cooled industrial equipment, showing broad application prospects for information perception and intelligent sensing of the industrial IoTs. [ABSTRACT FROM AUTHOR]

Micropower generation and micropropulsion are two emerging fields where micro- and miniature-scale combustors are anticipated to play a significant role. Today, there is a growing interest in combustion-based direct energy conversion modules such as thermoelectric and thermophotovoltaic micropower generators. In this study, the effects of swirl addition to fuel flow and airflow on combustor operational envelope, flame blowout limit, combustion efficiency, exhaust gas temperature, mean outer wall temperature, emitter efficiency, and normalized temperature standard deviation of a miniature-scale (mesoscale) combustor are studied under various equivalence ratios. The findings demonstrate that swirling flows improve the flame blowout limit and operational envelope of the combustor; however, this improvement is more significant for airflow swirl. Besides simultaneous swirling flows of fuel and air result in the highest blowout limit. Additionally, it has been shown that swirl addition improves combustion efficiency and causes a significant amount of heat to be generated, which raises the temperature of the exhaust gas, the mean outer wall temperature, and the emitter efficiency. Furthermore, mean outer wall temperature and emitter efficiency have the highest values for simultaneous swirling flows of fuel and air. It is also observed that increasing the fuel flow swirl number generally lessens the normalized temperature standard deviation (NTSD) and consequently improves the combustor wall temperature uniformity, while for the airflow swirl case, a swirler with 30° vane angle for airstream has a lower NTSD than a 45° vane angle swirler. The results obtained in this study provide useful information for designing a combustion-based direct energy conversion module. [ABSTRACT FROM AUTHOR]

Drying harvested grain crops prior to storage is a crucial task in the prevailing climatic conditions of Europe. Drying is an extremely energy-intensive process. Its inappropriate application leads to environmental pollution, quality deterioration, and ultimately significant financial losses. Various methods are available for conducting drying operations, with the mixed flow dryer being one of the most employed approach. The mixed flow dryer utilizes air blower systems to redirect the flow of the granulate. Previous research has indicated that uneven distribution of grain flow around the air blower lamellae can cause drying irregularities. By leveraging insights from a long-established classical mechanical problem (the Brachistochrone problem) and harnessing the explicit dynamical modelling capabilities offered by contemporary computing technology (Discrete element method), we have successfully devised an optimized lamella geometry that minimizes the non-uniformity of particle flow. [ABSTRACT FROM AUTHOR]

Wind speed is an important variable in the assessment of thermal comfort. Different types of meteorological devices provide different accuracy of air velocity (va) measurements, which under limited air flow conditions, may result in a discrepancy in actual thermal stress level. Simultaneous measurements on warm summer days, performed with a cup anemometer and hot-wire probe, prove that too high starting threshold of the first of these sensors can lead to a discrepancy of actual wind speed, and as a consequence can distort MRT (estimated with globe thermometers) and PET values on average up to 10 °C and 1 °C, respectively. [ABSTRACT FROM AUTHOR]

Bubble columns are used in the mining industry for mineral recovery but are also widely utilized in the chemical and petrochemical industry. The hydrodynamic characteristics of their performance is a field of interest with a number of points, which are nonetheless poorly understood, and a considerable amount of methods have aimed to shed light on the flow regimes that prevail in the columns. The study of the hydrodynamic part of a flotation process should consider characteristics such as air flow, volumetric gas fraction, flow field, and bubble size, along with the mechanical and design factors and pulp properties. The present work aims to elucidate the characteristics of the gas phase of a hybrid flotation system. For this purpose, a hybrid flotation column was designed and constructed and the bubbles size distributions at different radial positions in the flotation column were computed by analyzing high resolution digital images. A patented electrical impedance technique was employed to instantaneously measure the local volumetric gas fraction. Flow dispersion in the column was studied by residence time distributions using conductivity tracers. The experimental results are discussed to comprehend the variation in the gas fraction in the column. In particular, the study showed that the size of the bubbles changed from the center to the walls of the column, and this was observed both radically and vertically. Moreover, the size of the bubbles affected the volume fractions, and no coalescence of the bubbles was observed. Finally, the dispersion of the tracer in the working solution was distributed uniformly in the volume of the column, with a time difference for the four positions of the column. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study performed on silica sand samples to determine the effect of operating parameters (collector type and dosage, solids content in the pulp, pulp pH and air flow rate) on the concentrate grade and mass recovery in laboratory-scale column flotation. Through the analysis of variance (ANOVA), it was determined that the pulp pH had a significant impact on all four of the observed grade parameters (mass contents of SiO2, Al2O3, Fe2O3 and TiO2 in the concentrate). Air flow rate had a significant impact on the mass contents of SiO2 and Al2O3. The solids content in the pulp only significantly affected the mass content of Fe2O3. The mass recovery was significantly influenced by the pulp pH, with a high level of significance (p-value (p) = 0.002917), as well as by the air flow rate (p = 0.010285). On the basis of a model of the relationship between the respective grade parameters and tested operating variables, it was determined that with the use of the Aeromine 3030C collector (at a dosage of 500 g/t) the highest-grade concentrate regarding the mass contents of SiO2, Al2O3 and TiO2 was achieved with a pulp pH within a range from 2.4 to 3 and an air flow rate above 26 L/h. The lowest mass content of Fe2O3 in the concentrate was achieved at a pulp pH in a range from 2.2 to 2.8 and a solids content in the pulp between 2.0% and 3.5%. [ABSTRACT FROM AUTHOR]

Future automotive mobility is predominantly electric. Compared to existing systems, the requirements of subsystems change. Air flow for cooling components is needed predominantly when the car is in rest (i.e., charging) or at slow speeds. So far, actively driven fans consuming power and generating noise are used in this case. Here we propose a passive adaptive system allowing for convection-driven cooling. The developed system is a highly adaptive flat valve derived from the bordered pit. It was developed through an iterative design process including simulations, both structural and thermodynamic. In hardwoods and conifers, bordered pits enable the challenging transport of vertical fluids by locally limiting damage. Depending on the structure, these can close at sudden pressure changes and take the function of valves. The result of the biomimetic abstraction process is a system-integrative, low-profile valve that is cheap to produce, long-lasting, lightweight, maintenance-free, and noise-free. It allows for the passive switching of air flow generation at the heat exchanger of the cooling between natural convection or an active airstream without the need for complex sensing and control systems. The geometric and material design factors allow for the simple tuning of the valve to the desired switching conditions during the design process. [ABSTRACT FROM AUTHOR]

The gas blast arc-extinguishing lightning protection gap is a new type of lightning protection device based on airflow active arc-extinguishing. This paper establishes an airflow and arc mathematical model for calculating and analyzing air flow and arc motion processes. Besides, the finite element software ANSYS 14.0 is employed for the arc-extinguishing simulation in the pressure field, interaction arc, and airflow processes. Accordingly, the test analysis effects of the arc-extinguishing gap lightning protection test are verified. High-speed cameras, recording oscillograph arc-extinguishing images, and arc waveforms are employed in the process to obtain the airflow response time and arc-extinguishing time effectively based on the data analysis. Comparing the actual results with the simulation results demonstrates the arc-extinguishing reliability and provides an effective scientific basis for its practical application. [ABSTRACT FROM AUTHOR]

With the increasing demand for the resilient capacity of transformers in high-proportion renewable energy grids, the overload capacity of transformers and the thermal conductivity of winding insulation materials have been put forward as important requirements. In response to these requirements, a novel ceramic high temperature tolerance insulation winding is proposed in this paper and is applied in a ceramic insulated winding transformer. A combination of simulation and experimentation is used to analyze the thermal-flow characteristics of this transformer. The temperature and flow field distribution characteristics of transformers with both winding insulation methods (ceramic and Nomex paper) are compared. The internal mechanism of reflux near the iron core and high voltage winding under forced air cooling is clarified. A superior outside cooling condition is obtained. A prototype ceramic insulated winding transformer is developed and tested to verify the accuracy of the simulation model. The results show that the hotspot temperature of the ceramic insulated winding transformer under natural cooling is 10.7% lower than that of the Nomex paper insulated winding transformer. With forced air cooling of 2, 3, 4, 5, and 6 m/s applied at the bottom, the hotspot temperature of the ceramic insulated winding transformer is 11.4%, 10.5%, 9.7%, 14.0%, and 17.8% lower than that of the Nomex paper insulation winding transformer, respectively. Under forced air cooling, a reflux phenomenon is observed in both transformers in the vicinity of the iron core and high voltage winding due to the formation of adverse pressure gradient region and wall viscous force blocking. The strength of the reflux is affected by the magnitude of the forced air cooling flow velocity and the construction of the transformer. The optimal range of the external cooling flow velocity for the ceramic insulated winding transformer is 3–4 m/s. The errors between the simulated temperature and the measured temperature at the nine monitoring points of the prototype are all less than 5%, which verifies the effectiveness of the simulation model. The experimental and theoretical basis for the design and application of resilient capacity dry type transformers is provided by this research. [ABSTRACT FROM AUTHOR]

Nowadays, indoor air quality (IAQ) and the energy performance of buildings are two main scientific and technical challenges because they are in direct connection with human health and the depletion of energy resources. In this study, we analyzed the influence of an outdoor air flow introduced through a mechanical ventilation system, focusing on the two aforementioned topics. A standardized ventilation rate (25 m3/h/person) led to an increase in the indoor O3 concentration (from 5 μg/m3 to 50 μg/m3) and, simultaneously, to a decrease in the indoor CO2 concentration (from 2000 mg/m3 to 800 mg/m3), a decrease in the PM2.5 concentration (from 300 μg/m3 to 150 μg/m3), and the maintenance of a constant indoor HCHO concentration. In our study, a new, single indoor air quality index, IIAQ, is proposed. This new index presents different implications: on the one hand, it has the ability to simultaneously take into account several pollutant species, and on the other hand, it can prioritize the ventilation strategy that responds to the extreme values of a certain pollutant. Moreover, indoor air quality classes were elaborated, similar to energy classes. The possibility of using this new index simultaneously with energy consumption may lead to ventilation strategies that are adaptative to dynamic outdoor pollutant concentrations. [ABSTRACT FROM AUTHOR]

The microclimate environment can be conveniently controlled with accuracy by plant incubators, in which the cuttings propagation method can efficiently enhance seedling production. To ensure air flow evenly throughout the incubator, the scientific design of the air inlet is crucial. This study utilized a computational fluid dynamics (CFD) model to simulate the airflow patterns in a culture layer under different air inlet conditions. Furthermore, the optimal design parameters were determined by way of response surface methodology (RSM) and the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Adopting the optimal parameters, a prototype was manufactured, and a cuttings experiment was carried out with apple cuttings in the incubator. The results showed that the optimal air inlet radius is 90 mm, the optimal air inlet height is 188 mm, and the optimal uniform flow plate hole diameter is 13 mm. Meanwhile, the apple cuttings were able to root. Therefore, this incubator with optimal parameters can be used for cuttings. The study provides a methodological and theoretical basis for the future optimizing of air inlet parameters and promoting cuttings rooting. [ABSTRACT FROM AUTHOR]

Ventilation, carried out using centrifugal fans, is essential for obtaining good quality ambient air. Its role is to satisfy hygiene and comfort needs. It aims in particular to provide fresh air, in order to allow the proper functioning of the various devices, to evacuate air polluted by various pollutants and to combat humidity and condensation. In this context, the objective of this work is to study the internal flow of humid air for different concentrations in a fan rotor using the ANSYS-CFX software, based on the finite volume method. Flow turbulence is taken into account using the k-Ε model. The scientific contribution in this field consists of showing that the concentration of humid air has a considerable effect on the properties of the flow such as: pressure, shear stresses and flow speed which is in agreement with the results of experimental studies. This study can be used to locate the area's most exposed to this change in flow properties and which will result in premature damage to the blades by erosion and a reduction in fan efficiency. It will therefore be possible to take preventive measures to minimize the harmful effects of humidity concentration on centrifugal fans. [ABSTRACT FROM AUTHOR]

An unmanned underwater vehicle (UUV) powered by a compressed air power system is proposed to address challenges for battery/motor-powered vehicles under high-speed navigation, long endurance, and high mobility. These vehicles actively utilize supercavitation drag reduction by the exhausted gas from the compressed air power system. MATLAB/Simulink and FLUENT are used to establish theoretical models of the compressed air power system and ventilation supercavitation. The relationship between system power and navigation resistance is examined with different air flows, along with a comparison of endurance of different power vehicles at various speeds. The issue of the endurance-enhancing effect of supercavitation at high speed is investigated. The results demonstrate that increasing the air flow leads to higher power and reduced navigation resistance, and there is a balance between them. Furthermore, compared to the battery-powered vehicles with equal energy storage capacity, the compressed air power system shows 210.08% to 458.20% longer endurance times at speeds of 30 kn to 60 kn. Similarly, considering equal energy storage mass, it achieves 42.02% to 148.96% longer endurance times at high speeds (30 kn to 60 kn). The integration of supercavitation and air-powered systems can greatly enhance the endurance and maneuverability of the vehicle at high speeds while ensuring a compact system structure. The investigations could offer valuable ideas for the development and application of compressed air power systems for UUV at 30 kn to 60 kn or higher maneuvering. [ABSTRACT FROM AUTHOR]

Wearing facepieces is discussed in the context of increasing the volume of rebreathed air. We hypothesized that rebreathed air volume increases with increasing filtering facepiece (FFP) class and that persons breathing via facepieces compensate for the additional dead-space. We have determined the effective amount of rebreathed air for a surgical masks and FFP2 and FFP3 respirators in a physical model and determined tidal volumes, breathing frequency, blood oxygen saturation, and transcutaneously measured blood carbon dioxide partial pressure (PCO2) in lung-healthy subjects breathing without and with facepieces at rest and during exercising on a recumbent ergometer. Rebreathed air volume increased with the facepieces' protection class and with increasing inspiration volume by 45 ± 2 ml to 247 ± 1 ml. Ambient airflow reduced rebreathed air volume by 17% up to 100% (all p < 0.001). When wearing facepieces, subjects increased tidal volume (p < 0.001) but not breathing frequency. Oxygen saturation was not influenced by facepieces. With FFP3 respirators PCO2 increased by up to 3.2 mmHg (p < 0.001) at rest but only up to 1.4 mmHg (p < 0.001) when exercising. Discomfort of breathing increased with increasing protection class of the facepiece but was consistently perceived as tolerable. We conclude that the amount of rebreathed air increases with increasing protection class of facepieces. Healthy adults were capable to compensate the facepieces' dead-space by adapting tidal volume at rest and during physical activity; thereby they tolerated moderate increases in PCO2. Ambient airflow may considerably reduce the amount of facepiece related rebreathed air. [ABSTRACT FROM AUTHOR]

Air compressors are widely used in industrial fields. Compressed air systems aggregate air flows and then supply them to places of demand. These huge systems consume a significant amount of energy and generate heat internally. Machine components in compressed air systems are vulnerable to heat, and, in particular, a radiator to cool the heat of the overall air compressor is the core component. Dirty radiators increase energy consumption due to anomalous cooling. To reduce the energy consumption of air compressors, this mechanism emphasizes a machine learning-based radiator fault detection, using features such as RPM, motor power, outlet pressure, air flow, water pump power, and outlet temperature with slight true fault labels. Moreover, the proposed system adds an LSTM-based motor power prediction model to point out the initial judgment of radiator fault possibility. Via the rigorous analysis and the comparison among machine learning models, this meticulous approach improves the performance of radiator fault prediction up to 93.0%, and decreases the mean power consumption of the air compressor around 2.24%. [ABSTRACT FROM AUTHOR]

This study compared computational fluid dynamic (CFD) model predictions on aerosol deposition in six asthmatic patients to the in-vivo results of the same group. Patient-specific ventilation and internal air distribution were prescribed using inspiratory and expiratory CT scans of each patient, accounting for individual lobar air flow distribution. Moreover, the significant influence of realistic mouth and throat geometries on regional deposition is demonstrated. The in-vivo data were obtained from single photon emission computed tomography (SPECT) in 6 subjects with mild asthma selected from a database of historical clinical trials. The governing flow and particle tracking equations were solved numerically using a commercial CFD tool, and the modeled deposition results were compared to the SPECT data. Good agreement was found between the CFD model, applying k-ω SST turbulence model, and SPECT in terms of aerosol deposition. The average difference for the lobar deposition obtained from CFD model and SPECT/CT data was 2.1%. The high level of agreement is due to applying patient specific airway geometries and inspiratory/expiratory CT images, anatomical upper airways, and realistic airway trees. The results of this study show that CFD is a powerful tool to simulate patient-specific deposition if correct boundary conditions are applied and can generate similar information obtained with functional imaging tools, such as SPECT. [ABSTRACT FROM AUTHOR]

Background: Nasal septal deviation is a common anatomical variation that can lead to significant impairment in nasal airflow and quality of life. Septoplasty is a surgical procedure aimed at correcting septal deviation to alleviate symptoms and improve nasal function. Methods: A prospective study was conducted over a one-year period, involving 60 patients with septal deviation who underwent septoplasty. Pre- and post-operative assessments included subjective quality of life measures (Rhinoplasty Outcome Evaluation [ROE] questionnaire, 36-item Short Form Health Survey [SF-36]), objective measures of nasal function (acoustic rhinometry, peak nasal inspiratory flow [PNIF]), and nasal obstruction symptom evaluation (NOSE) scale. Results: Septoplasty resulted in significant improvements in subjective quality of life measures, as evidenced by increased ROE and SF-36 scores post-operatively. Objective measures of nasal function also showed improvement, with increased nasal volume and airflow post-septoplasty. These improvements were sustained over the one-year follow-up period. Conclusion: Septoplasty is an effective treatment option for patients with septal deviation, leading to improvements in both subjective quality of life measures and objective measures of nasal function. [ABSTRACT FROM AUTHOR]

Postharvest cooling techniques applied for fresh fruits and vegetables (FFVs) have received considerable research efforts in the recent years. The research efforts have been geared towards reducing respiration rate, weight loss, and water loss during cooling whilst reducing field heat and microbial activity in FFVs. Some recent advances including the application of disinfectants such as chlorine dioxide (ClO2), 1-methylcyclopropene (1-MCP) and calcium chloride (CaCl2) in hydrocooling, modification of air flow pattern and vent design during forced air cooling, and integration of vacuum cooling with modified atmosphere system have been applied as effective methods in reducing respiration rate and weight loss, producing enhanced quality of cooled fruits and vegetables. However, information on the recent advances in cooling techniques of FFVs would be of great benefits to the food engineers and food industries. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel data-driven optimization approach for trajectory-based air traffic flow management (ATFM). A key aspect of the proposed approach is the inclusion of airspace users' trajectory preferences, which are computed from traffic data by combining clustering and classification techniques. Machine learning is also used to extract consistent trajectory options, whereas optimization is applied to resolve demand-capacity imbalances by means of a mathematical programming model that judiciously assigns a feasible four-dimensional trajectory and a possible ground delay to each flight. The methodology has been tested on instances extracted from the Eurocontrol data repository. With more than 32,000 flights considered, we solve the largest instances of the ATFM problem available in the literature in short computational times that are reasonable from the practical point of view. As a by-product, we highlight the trade-off between preferences and delays as well as the potential benefits. Indeed, computing efficient solutions to the problem facilitates a consensus between the network manager and airspace users. In view of the level of accuracy of the solutions and the excellent computational performance, we are optimistic that the proposed approach can make a significant contribution to the development of the next generation of air traffic flow management tools. [ABSTRACT FROM AUTHOR]