Varying Air Flow Research Articles

Effect of laser powder bed fusion gas flow rate on microstructure and mechanical properties of 316 L stainless steel

The inert protective gas flow rate during laser powder bed fusion (LPBF) molding is an important environmental condition. The protective gas not only prevents parts from being oxidizing, but also significantly affects spatter particle removal and particle migration on the powder bed surface. There are relatively few systematic comparative studies reported on the effect of gas flow rate on the movement of two types of powders. Therefore, in this study, three flow rate environments, low, medium and high, were designed for multi-scale experimental analysis of the quality, microstructure, mechanical properties and defects of molded samples. It was observed that the movement of the powder that dominated the sample defects was different in the three environments as the gas flow velocity was adjusted. Under low flow conditions, spatter particles are the main contributor to the creation of defects such as porosity, resulting in poor surface quality (TOP: Sq = 14.023, Side: Sq = 22.006), elevated surface oxygen content (Wt. = 1.7 %), increased grain size, and i a higher number of pores and spatter particles. Consequently, this led to the lowest density, microhardness, and mechanical properties among the three sample groups. High flow rates increased the removal of spatter particles compared to low flow rates, resulting in the highest surface quality (top: Sq = 11.528, Side: Sq = 14.051) and the lowest surface oxygen content (Wt. = 0.88 %). However, under the influence of high flow rates, surface particle migration becomes an important factor in defects, leading to an increase in grain size, porosity, and unfused particles compared to medium flow rates. This leads to a decrease in density, microhardness and elongation. This study reveals, through multi-scale experimental characterization, the mechanism by which varying air flow rates affect powder movement, and hence the microstructure and properties of parts. These findings provide new insights for device development and coupled multi-physics field computational studies.

The Prediction of the Leakage Airflow Rate Using the Supply and Return Airflow Rate in a Variable Air Volume System

Pressure differences in the envelope of a building result in leakage airflow (i.e., the unintended flow of air). This can lead to increased building heating and cooling energy, decreased thermal comfort for occupants, and the spread of moisture. To address this problem, it is necessary to know the leakage airflow in a building. Generally, the leakage airflow in a building is calculated by determining the leakage function through fan pressurization methods, such as the blower door test, and substituting the pressure difference measured by the pressure sensor. However, it is difficult to install continuous pressure sensors in an operating building. Therefore, this study proposes a method to utilize the supply and return airflow of an air conditioning system to predict the variation in the leakage airflow with changing indoor and outdoor airflow, and the efficacy of this approach was verified through experiments. The experiment measured the indoor and outdoor pressure difference of the building with a change in the speed of the supply and return fans and the opening rate of the variable air volume (VAV) damper. As a result of the experiment, the indoor–outdoor pressure difference is proportional to the difference between the indoor supply airflow and the ventilation airflow. In addition, the relationship between the pressure difference and the leakage airflow was derived through the pressurization/decompression method using an air handler, and the leakage airflow from the pressure difference generated by the operation of the air conditioning system was calculated. Lastly, the relationship between the supply and return airflow difference and the leakage airflow was derived based on the experimental results, and the leakage airflow was predicted based on the relationship.

Optimizing Fish Feed Pellets Handling Systems to Minimize Microplastics Emissions - A Pilot Test Based Approach

The fisheries and aquaculture industries are vital components of global food production, yet they also contribute to release of microplastics into marine environments, posing risks to ecosystem health and seafood safety. Among the contributing factors, the erosion of feeding pipes during the pneumatic conveyance of fish feed pellets stands out as a significant source of microplastic pollution. This study focuses on optimizing feed pellet conveying systems in fish farms to minimize microplastic emissions while maximizing pipeline lifespan and pellet integrity. Using high-density polyethylene (HDPE) pipes commonly found in aquaculture facilities, the impact of air velocity and pipeline configuration on pipe wall erosion and pellet breakage was investigated. Through pneumatic conveying tests, the effects of varying air flow rates and bend radii were assessed on pipeline wear and feed pellet integrity. The findings of the study underscored the importance of optimizing operating parameters to bring a balance between preventing pipe blockages and minimizing abrasive impacts on pellets and pipeline surfaces. Furthermore, a simulationbased approach to optimize feeding system performance is presented, integrating the experimental results into a computational model. This model allows for the evaluation of different operating conditions and pipeline configurations, offering insights into costeffective strategies for reducing microplastic emissions while maintaining efficient feed delivery to fish populations. Ultimately, this research provided practical recommendations and best practices for the aquaculture industry to mitigate microplastic pollution from feeding pipes. By optimizing feed pellet conveying systems, environmental sustainability can be enhanced, seafood quality be preserved, and bolster consumer confidence in aquaculture products.

A machine learning based regression methods to predicting syngas composition for plasma gasification system

Plasma gasification is considered a promising technology that converts waste into energy through an environmentally friendly process. This research focuses on predicting the outputs of this process, utilizing ML regression techniques. Data from previous studies involving different solid fuels were collected, and four regression techniques Random Forest Regression, Gaussian Process Regression, Decision Tree Regression, and Support Vector Regression were employed to predict the levels of CO2, CO, N2, O2, H2, and CH4 in the plasma gasification process. The experimental dataset was gathered using a microwave gasifier with varying air flow rates (50–100 sL/min) and plasma power (3–6 kW). GPR a coefficient of determination (R2) values exceeding 0.983 for all outputs and low NRMSE and MSLE values (<0.082 and <0.00123, respectively). RFR also performed well, with R2 values >0.98 for all outputs except CH4 and CO2. SVR exhibited the least favorable performance, while DTR showed intermediate results. Plasma gasification Machine Learning modeling has proven to enable the prediction of the high-complexity chemical reaction chain in gasification. These models hold promise for applications in simulation environments and can be integrated into microcontroller-based systems for practical use for optimization and control. By this means, the cost of plasma gasification processes would be reduced, and so the plasma gasification system would be more flexible.

Uncertainty quantification: For an IAQ and energy performance assessment method for smart ventilation strategies

In new low-energy buildings or buildings after thermal refurbishment, the envelope high airtightness could have an impact on air renewal and could decrease the indoor air quality (IAQ). In this context smart-ventilation systems with variable airflows could play a role in providing better IAQ without compromising the energy performance.However, smart-ventilation strategies are quite recent, and their benefits need to be clearly quantified. This article, proposes to quantify the uncertainty of a recent multi-criteria performance assessment method, using global RBD-FAST sensitivity analysis. The impact of the pollutant emissions scenarios, model input parameters and ventilation strategies is assessed.Five ventilation systems were studied: two constant airflow, one humidity-controlled and two humidity/CO2 controlled, applied on a French low-energy house. 2500 simulations were performed to calculate 504 sensitivity indices across 12 input variables and 9 output performance indicators. The sensitivity analysis shows that occupant bio-effluent, formaldehyde and PM2.5 emissions rates are responsible for 11 %–87 % of the uncertainty for the IAQ performance indicators. The PM2.5 deposition velocity parameter is responsible for 50 % of the uncertainty on the PM2.5 indicator, which was an unknown impact. In addition, the benefits of humidity-controlled ventilation were highlighted regarding energy performance, with, in average, 20 % lower heat-loss compared to constant airflow ventilation. Moreover, smart-ventilation provides clear IAQ benefits without drastically increasing the energy demand. This work demonstrates the potential of the proposed evaluation method for ventilation performance assessment.

Experimental study on the suppression of inlet blockage in rotating detonation combustor by porous-wall

The rotating detonation combustor (RDC) is renowned for its ability to provide substantial pressure gains. Nonetheless, during the stable operation of the RDC, the high-pressure rotating detonation wave (RDW) at the combustor inlet induces an increase in upstream chamber pressure, ultimately compromising engine stability and performance. To fully harness the performance advantages of the turbine-based continuous rotating detonation engine (TBCRDE) while maintaining engine stability, a porous-wall RDC has been developed to alleviate intake blockage and mitigate upstream chamber pressure rise. The operating modes, pressure rise characteristics, and performance parameters of both the porous-wall RDC and the reference configuration were systematically evaluated across varying air flow rates and nozzle designs. This analysis concentrated on the operational characteristics of the porous-wall RDC and its mechanisms for suppressing upstream chamber pressure rise. The findings reveal that the porous-wall RDC significantly extends the stable operating range and effectively reduces upstream chamber pressure rise by minimizing intake blockage. Specifically, the stable operating range is enhanced by 50 % at an outlet area ratio of 0.33, with stable rotating detonation combustion achieved at an outlet area ratio of 0.25. At an air flow rate of 1 kg/s and an outlet area ratio of 0.33, the chamber pressure rise is optimally suppressed, demonstrating a maximum reduction of approximately 16.4 %. The total pressure recovery coefficient of the combustor was analyzed, taking into account both intake loss and combustor pressure gain capabilities, and the propulsion performance of the two configurations was compared. The porous-wall RDC effectively reduces intake loss while slightly diminishing combustor pressure gain capability, resulting in a marginal increase in the total pressure recovery coefficient. Although this leads to a slight reduction in propulsion performance during chamber pressure rise suppression, the overall engine matching environment benefits from enhanced matching stability. Consequently, other engine components experience a reduced performance decline. Therefore, the implementation of a porous-wall structure is anticipated to improve the overall propulsion performance of the engine.

Seasonal variation in airborne microbial communities of the Akiyoshido Cave: Lampenflora dispersed by phototrophic bioaerosols

Lampenflora, such as phototrophic microorganisms, multiply on speleothem surfaces under the show-cave lighting, causing deterioration of the natural and cultural heritages of the caves. Speleothems change color from white to green through microbial photosynthesis and are destroyed by microbial metabolisms. Aerosol transmission are suspected to disperses photosynthetic microorganisms. However, the mechanism underlying the process remains unclear, because the complexity of air ventilation affects the cave atmosphere. In the present study, we collected aerosol samples from the Akiyoshido Cave, which is a special natural monument in Japan and possesses various types of speleothems, to analyze microbial concentrations and communities in the cave atmosphere. Under a fluorescence microscope, phototrophic and heterotrophic microorganisms were observed in the aerosols with in the cave. The aerosol concentrations showed seasonal changes depending on air-flow variations in cave ventilation. High-throughput DNA sequencing targeting 16S rRNA genes revealed that the airborne bacterial communities inside the cave were dominated by members of the phyla Actinomycetota, Bacillota, and Pseudomonadota, originating from the external terrestrial, phyllosphere or freshwater environments, as well as its interior (guano). Cyanobacteria showed small relative abundances (from 1.0 to 10%) randomly in the aerosol samples at several locations in the cave, suggesting that the lampenflora-derived cyanobacteria were dispersed throughout the cave by the ventilation. Additionally, phototrophic microorganisms closely related to the relatives of the genera Leptolyngbya, Calothrix, and Chroococcidiopsis from the phylum Cyanobacteria were isolated from the aerosol samples. These results confirm that Cyanobacteria are one of the candidate microorganisms responsible for lampenflora dispersion and are “alive and airborne” in caves.

Numerical investigation on the tracer followability of nitrogen droplets over the airfoil in cryogenic wind tunnel

Cryogenic wind tunnels (CWT) achieve high Reynolds number aerodynamic performance measurements by cooling the medium with liquid nitrogen. Utilization of naturally-occurring liquid nitrogen droplets as tracer particles for non-intrusive measurement applications in CWT shows great potential in the previous work. However, the droplet motion characteristics over the airfoil remain to be investigated, and the followability evaluation approach is lacking. Accordingly, an Euler-Lagrange model for transonic particle flow over the NACA0012–64 airfoil was established. The effect of flow characteristics on the particle motion was explored. The results reveal that the flow separation and shock wave phenomenon over the airfoil causing velocity deviation between airflow and droplet. The shock wave is the main deviation driver, and flow separation causing trace blind zones. Droplets larger than 10 μm fail to effectively follow the variation of airflow. The blind zone enlarges with angle of attack (AoA), particularly when AoA exceeding 10 degrees. Moreover, Stokes number is found to be inadequate for characterizing the followability of tracer particles in turbulent flow. Consequently, an evaluation method based on the Basset-Boussinesq-Oseen equation was developed. This research provides theoretical and technical support for advancing the use of nitrogen droplets as tracer particles in CWT.

Ground, Ceiling and Wall Effect Evaluation of Small Quadcopters in Pressure-controlled Environments

Multicopters are used for a wide range of applications that often involve approaching buildings or navigating enclosed spaces. Opposed to the open spaces in obstacle-free environments commonly flown by fixed-wing unmanned aerial vehicles, multicopters frequently fly close to surfaces and must take into account the airflow variations caused by airflow rebound. Such disturbances must be identified in order to design algorithms capable of compensating them. The evaluation of ground, ceiling and wall effects using two different test stands is proposed in this work. Different propellers and sensors have been considered for testing. The first test setup used was placed inside terraXcube’s large climatic chamber allowing a precise control of temperature and pressure of around 20°C and 1000 hPa, respectively. The second test setup is located at the University of Denver (DU) Unmanned Systems Research Institute (DU2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^2$$\\end{document}SRI) laboratory with a stable pressure of around 800 hPa. Two different fixed 6 degrees of freedom force-torque sensors have been used for the experiments, allowing to sample forces and moments in three orthogonal axes. The tests simulate a hovering situation of a quadcopter at different distances to either the ground, the ceiling or a wall. The influence of the propeller size, rotation speed, pressure and temperature have also been considered and used for later dimensionless coefficient comparison. A thorough analysis of the measurement uncertainty is also included based on experimental evaluations and manufacturer information. Experimental data collected in these tests can be used for the definition of a mathematical model in which the effect of the proximity to the different surfaces is evaluated.

Environmental conditions in equine indoor arenas: A descriptive study

Indoor arenas do not always include mechanical ventilation or stirring fans and occupancy by horses and humans can be sporadic and inconsistent, which creates a challenging space for understanding and predicting variations in temperature, moisture, and airflow. To understand the interior environment within indoor arenas, monitoring was conducted at 15 facilities within 200 kilometres of Lexington, KY. Environmental monitoring of dry bulb temperature, relative humidity, dew point temperature, air speeds, and solar radiation took place over 7 days in the winter and summer to examine temporal variability. Environmental data was collected every 5 minutes using the HOBO RX3000 Remote Monitoring Station with the HOBOnet Temp/RH Sensor, HOBOnet Solar Radiation (Silicon Pyranometer) Sensor, and HOBOnet Ultrasonic Wind Speed and Direction Sensor. Clear seasonal differences and diurnal patterns were evident in all environmental conditions, but the relative humidity. The relative humidity and dew point temperatures indicated moisture could be an issue in many of the indoor arenas. High relative humidity and excess moisture can negatively impact horse and human health as well as the lifespan of the facility. Similar results to previous spatial variability indoor arena characterizations were observed during the environmental monitoring with air speeds being below the threshold for still air in livestock facilities (0.51 m s-1). Sensor technology and implementation provides a better understanding of the interior environment and how indoor arena design can impact it.

A novel energy harvesting technology from the movements of air masses

The displacement of air masses caused by the movement of objects or vehicles is often characterized by considerable energy content, which, with appropriate technologies, can be partially recovered. In this sense, numerous scientific works consider rail transport as a possible context for application. However, the literature in the sector highlights how using existing wind technologies in these areas involves many difficulties, mainly related to the turbulent and impulsive nature of the airflows generated. This work presents the architecture and general aspects of an innovative technology for obtaining electrical energy from variable and impulsive airflows, such as those due to the rapid transit of railway trains in tunnels, without precluding its use in other similar fields. The innovative aspect mainly concerns the independent control of two distinct typologies of bladed elements, which can also have translational movement and drag-based and lift-based aerodynamic behavior to improve the adaptability of the embodiment to the site’s fluid dynamic and geometric characteristics. Furthermore, the structural simplification of the apparatus, shifting some of the technological complexity to the control systems, brings further advantages in terms of construction cost, robustness, maintenance, reuse, and transferability to different contexts. Of course, the counterpart of these benefits lies in the software and hardware of the control devices. Analytical models to determine the non-dimensional performance coefficients of the two basic types have been reported as has the architectural model of the control system. The technology shown in this work is protected by an EP and US Patent.

Assessment of nasal respiration and three-dimensional airway volume changes in orthognathic surgery patients

ObjectivesThe aim of this study was to evaluate the effect of maxillary movements in orthognathic surgery on nasal airway volume change and its correlation with airflow and resistance. Materials and methodsThis study included 25 patients (8 male, 17 female) with Class II (6 patients) or Class III (19 patients) malocclusion. All patients underwent Le Fort I and bilateral sagittal split ramus osteotomy. Nasal airflow and resistance were measured by using rhinomanometry and acoustic rhinometry pre and six months post-operatively. Nasal volume was measured using computed tomography before surgery and six months after surgery. ResultsNasal volume increased in 10 out of 11 patients with CCW (counterclockwise) rotation and decreased in 1 patient while, nasal volume increased in 5 patients with CW (clockwise) rotation and decreased in 9 patients. Superior nasal airway volume increased significantly, while the effects on nasal flow and resistance were not significant. Additionally, no significant correlation was found between airway volume changes and variations in airflow and resistance. ConclusionCCW rotation in orthognathic surgery patients significantly increased superior nasal airway volume but did not improve nasal airway flow and resistance

Study on wind-sand dynamics observation of blowout in Xilingol sandy grassland

This study investigated airflow changes and sediment transport in the blowouts of the sandy grassland in Xilingol, Inner Mongolia. The results show that the wind direction inside the blowout is influenced by the direction of the incoming wind. Specifically, when the angle between the incoming wind direction and the long axis of the blowout is less than 15°, both sides of the wall tend to generate a wind flow towards the east exit. Meanwhile, the main airflow along the central axis airflow deflects towards the north side wall. However, when the angle is greater than 15°, the airflow on the north wall first disperses and then converges towards the wellbore. Conversely, the airflow on the south wall blows out in a southeast direction, and the axial airflow deflects towards the south wall. The rate of wind speed acceleration on both sides of the wall increases with height within the blowout but decreases along the central axis section. Higher wind speeds correlate with greater cumulative sand transport heights. Sand transport heights on both sides of the deflation basin are smaller than those along the central axis section, with the opposite observed in the depositional lobe. The rate of sand transport is primarily influenced by wind direction and wind speed, followed by, topography, vegetation coverage, slope, and aspect. These variations in airflow, combined with sediment transport, lead to the blowout taking on a develop deeper, longer, and wider shape.

Assessing nasal airway resistance and symmetry: An approach to global perspective through computational fluid dynamics.

This study aimed to explore the variability in nasal airflow patterns among different sexes and populations using computational fluid dynamics (CFD). We focused on evaluating the universality and applicability of dimensionless parameters R (bilateral nasal resistance) and ϕ (nasal flow asymmetry), initially established in a Caucasian Spanish cohort, across a broader spectrum of human populations to assess normal breathing function in healthy airways. In this retrospective study, CT scans from Cambodia (20 males, 20 females), Russia (20 males, 18 females), and Spain (19 males, 19 females) were analyzed. A standardized CFD workflow was implemented to calculate R-ϕ parameters from these scans. Statistical analyses were conducted to assess and compare these parameters across different sexes and populations, emphasizing their distribution and variances. Our results indicated no significant sex-based differences in the R parameter across the populations. However, moderate sexual dimorphism in the ϕ parameter was observed in the Cambodian group. Notably, no geographical differences were found in either R or ϕ parameters, suggesting consistent nasal airflow characteristics across the diverse human groups studied. The study also emphasized the importance of using dimensionless variables to effectively analyze the relationships between form and function in nasal airflow. The observed consistency of R-ϕ parameters across various populations highlights their potential as reliable indicators in both medical practice and further CFD research, particularly in diverse human populations. Our findings suggest the potential applicability of dimensionless CFD parameters in analyzing nasal airflow, highlighting their utility across diverse demographic and geographic contexts. This research advances our understanding of nasal airflow dynamics and underscores the need for additional studies to validate these parameters in broader population cohorts. The approach of employing dimensionless parameters paves the way for future research that eliminates confounding size effects, enabling more accurate comparisons across different populations and sexes. The implications of this study are significant for the advancement of personalized medicine and the development of diagnostic tools that accommodate individual variations in nasal airflow.

Wearing a Surgical Vest With a Sterile Surgical Helmet System Decreases Contamination of the Surgical Field

BackgroundSterile surgical helmet systems are frequently utilized in total knee arthroplasty procedures to protect the surgeon while maintaining a comfortable working environment. However, common helmet systems pressurize the space between the surgical gown and the surgeon’s skin. In gowns with a back seam, this may allow contaminated skin particles to escape into the surgical field. By measuring bacterial colony-forming units (CFUs), this study sought to determine if occlusion of the open back seam reduced the risk of potential contamination. MethodsFirst, qualitative analysis depicting airflow variations between gown configurations was performed using the Schlieren Spherical Mirror imaging system. Each gown configuration consisted of a sterile surgical helmet and one of 3 gown configurations: a standard gown with rear-tied closure, a standard gown with a surgical vest, and a zippered Toga-style gown. Next, a surgeon then performed simulated surgical activities for 60 minutes within a 1.4 m3 isolation chamber with work surfaces and controllable filtered air exchanges. During each procedure, contaminated particles were collected on sets of agar settle plates positioned directly behind the surgeon. Upon completion, the agar plates were incubated in a biolab, and the number of bacterial and fungal CFUs was counted. The experimental procedure was repeated 12 times for each gown configuration, with sterilization of the chamber between runs. Contamination rates were expressed as CFUs/m2/h. ResultsThe mean contamination rate measured with the standard gown was 331.7 ± 52.0 CFU/m2/h. After the addition of a surgical vest, this rate decreased by 45% to 182.2 ± 30.8 CFU/m2/h (P = .02). Similarly, with the Toga-style gown, contamination rates dropped by 49% to 170.5 ± 41.9 CFU/m2/h (P = .01). ConclusionsWhen used in conjunction with surgical helmet systems, conventional surgical gowns do not prevent potential contamination of the surgical field. We recommend that staff within the surgical field cover the back seam of standard gowns with a vest or don a zippered Toga-style gown.

Nitrogen removal and nitrous oxide emission from moving bed biofilm reactor (MBBR) under different loads and airflow

Total nitrogen (TN) removal by sewage treatment required the development of nitrifying and denitrifying activities; however, these metabolite activities can produce and emit nitrous oxide (N2O), one of the greenhouse gases (GHG). With the expansion of sewage treatment in the world, compact systems such as moving bed biofilm reactor (MBBR) may be promising, mainly in more populated cities. However, little is known about N2O emission by the MBBR. This work investigated the N-NHx and TN removal, N2O production and emission and nitrogen mass balance in a MBBR under organic load and airflow variation. The highest TN removal (47%) was observed under higher load and higher aeration rate. Meanwhile, the MBBR under lower load and lower airflow had the lowest efficiency of TN and N-NHx removal probably due to a lower nitrifying activity. The N2O emission factors were lower than 1.6% (value estimated by the IPCC for sewage aerobic treatment systems). In addition, in the essay with higher load and lower airflow, half of removed TN was released by settled sludge and there is little research about this subject. Therefore, the MBBR showed to be a promising process for nitrogen removal with little emission of N2O even under different operational conditions that normally can occur in sanitary sewage system in cities around the world.

Diffusion characteristics of coal dust associated with different ventilation methods in underground excavation tunnel

To further explore the dust diffusion behavior and percentage of different particle sizes under various ventilation methods and perfect the existing research, this work systematically investigated the space−time variation of airflow and dust under three ventilation modes and elaborated on the dust control mechanism and proportion of particle size. The results indicated that using the dust removal fan could reduce the spread of high concentration dust. With the increase in wind volume of the dust removal fan (Qe), dust removal efficiency increased from 34.8% to 74.6%. Meanwhile, the dust of small particle size spread with the airflow towards the rear of the excavation tunnel, but the vortex generated by the larger Qe made it challenge to discharge respiratory dust. The air curtain installation position was determined at 20 m, which restricted the high dust concentration within 10 m so that most of the coal dust was discharged from the exhaust duct. This technology effectively diminished the concentration of dust, resulting in the total dust removal efficiency increased to 89.8% and 98.5%. The results could provide theoretical guidance for dust control and removal strategies of coal mine excavation tunnels.

PSO‐SMADRC for altitude test facility intake pressure environmental simulation system

AbstractTo address significant disturbances, including sudden air flow variation, model uncertainty, and unavoidable measurement noises during aeroengine transient tests in the intake environmental pressure simulation system (IEPSS), a sliding mode active disturbance rejection controller (SMADRC) is designed. The sliding mode control in SMADRC can deal with unmatched disturbances that are beyond the capabilities of the extended state observer (ESO) in ADRC. And the particle swarm optimization (PSO) algorithm is introduced to tune and optimize the controller parameters to further enhance the performance. To validate the effectiveness of the proposed method, simulations are conducted on the IEPSS software platform. The simulation results clearly demonstrate PSO‐SMADRC can reduce the mean squared error by 60.9%, the input oscillation by 68.7%, and the maximum deviation by 53.9%, compared with LADRC originally applied in the IEPSS.

Unraveling the influence of varied airflow patterns on atmospheric instabilities, rain microphysics, and cloud features over Delhi, the capital city of India

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.

Micro-environmental factors impact breathing zone exposures: A simulated petrochemical manufacturing facility task

This study investigates the impact of micro-environmental factors on worker breathing zone exposure levels in petrochemical facilities. A laboratory simulation study evaluated near-field exposure to methane for a typical maintenance task. Individual and combinations of micro-environmental factors significantly affected methane exposure. Airflow direction and speed were significant determinants of exposure concentration reduction. A side airflow direction at medium to high speed produced the lowest gas concentration in the breathing zone. Worker body orientation relative to the methane emission point was also a critical factor affecting gas concentration in the worker's breathing zone. The study provides insights into how variations in airflow and small changes in position impact near-field exposures for petrochemical tasks, guiding industrial hygiene professionals' training on qualitative exposure estimation and providing input for near-field exposure modeling to guide quantitative exposure and risk assessment.