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The high-speed movement of trains generates train-induced wind, commonly referred to as slipstream, which presents a specific safety concern for passengers and personnel. Yet, the fastening system employed to secure ballastless tracks, characterised by its complex shape, substantial quantity, and dense arrangement, remains inadequately investigated regarding its influence on train aerodynamics. In the present study, a sliding mesh technique was employed to comparatively examine the impact of different track configurations--trackless, track-only, and track with a fastening system--on the aerodynamic characteristics, slipstream formation, and wake turbulence induced by trains. The results indicate that the tracks and the fastening system increased the drag force coefficient by 0.73% and 2.05%, respectively, compared with no track. Additionally, tracks and the fastening system had a significant impact on the slipstream velocity near the train and ground. Tracks notably altered the shape of the wake near the ground, and the fastening system exacerbated this phenomenon. Further, the fastening system further intensified the generation of secondary vortices at track and footstep locations. [ABSTRACT FROM AUTHOR]

Proper consideration should be given to the stability of new concrete in order to assure the quality of building engineering, while also demanding its excellent flowability. The inadequate initial state stability negatively impacts the long-term durability of reinforced concrete structures, although this issue has not been well addressed. This work focuses on assessing the aerodynamic response of concrete ceilings reinforced with advanced functionally graded nano-materials. As the reinforcement of the current concrete structure, graphene oxide powders (GOPs) are used with improved material properties than other types of reinforcement. For mathematical modeling of the current structure, Reddy's Higher-order Shear Deformation Theory is used to model the current work's displacement fields. Also, the perturbation aerodynamic force is mathematically described using the Bernoulli equation for potential flow. After that using a method that involves separating variables, we may get the answer for the aerodynamic pressure in its ultimate form. Haber-Schaim foundation made of auxetic material in the Cartesian coordinate system is used to model the foundation of the current work with high accuracy. After obtaining the governing equations and associated boundary conditions, a meshless approach with weighted orthogonal basis and Kronecker delta-based shape functions are used to solve the equations. Finally, some suggestions for improving the aerodynamics and flutter velocity of airflow of the presented concrete plate reinforced by GOPs are presented for related aerodynamics industries. [ABSTRACT FROM AUTHOR]

Sandstorms have destructive effects on railway infrastructures due to the movement and erosion of sand. One of the proposed solutions to reduce the impact of windblown sand on desert railways is the hump slab track superstructure. This system entails removing the ballast layer and elevating the rails using concrete foundations called humps, which create sand movement channels beneath the rails. The hump's geometry must not only meet optimal aerodynamic conditions but also ensure ample clearance for sand passage, maintaining structural stability and efficient railway performance. In this study, the aerodynamic evaluation of various hump geometry is examined considering the elliptical (EL) and semicircular-rectangular (CR) shapes. Simulations are carried out using 3D computational fluid dynamics in ANSYS Fluent software. A gas–solid two-phase model, comprising a distinct phase for sand particles and another for air, is developed to assess the sand movement capacity through the selected hump geometries. A wind tunnel experiment is then performed on a prototype of a hump slab track to validate the software model. The findings highlighted that the CR shape, with a height of 25 cm, resulted in the most favorable outputs. [ABSTRACT FROM AUTHOR]

Efficient aerodynamics significantly impact your vehicle's overall efficiency. Enhancing vehicle performance and fuel economy hinges on optimizing aerodynamics. Reduced drag equates to decreased resistance against air, requiring less energy for propulsion. This study employs numerical investigation utilizing ANSYS Fluent computational fluid dynamics (CFD) simulations to identify the aerodynamic characteristics of an SUV. The goal is to gain insights into the vehicle's aerodynamics. This study involves the creation of a 3D model of the SUV car, which is then subjected to simulated wind channel testing. ANSYS Fluent is employed to simulate the airflow around the car, enabling the estimation of drag and lift forces. The primary objective of the study is to achieve an optimal shape design for the SUV by varying the glass inclination angle within the range of 145° to 160°, and subsequently observe its effects. It has been observed that as the glass inclination angle increases, both drag and lift forces decrease gradually, with optimal results observed at a 160° inclination angle. Additionally, detailed observations of pressure and velocity fluctuations were made to further analyze flow phenomena. Adjusting the angle could potentially modify airflow around the vehicle, potentially minimizing drag by facilitating smooth airflow over the car, thus reducing resistance. [ABSTRACT FROM AUTHOR]

Turbulence modelling is crucial in predicting train aerodynamics while its performance is closely related to the model closure coefficients. To reveal the influence, uncertainty quantification and sensitivity analysis are conducted on the closure coefficients of the turbulence model for high-speed train. The standard k-ϵ model for Reynolds-averaged Navier-Stokes simulation is utilized. Five main closure coefficients are analyzed using the Non-Intrusive Polynomial Chaos method to assess their uncertainty and sensitivity with respect to the aerodynamic force and pressure field. The results indicate that the drag exhibits higher sensitivity to the model coefficients with an uncertainty interval as high as 53%, especially for the tail car. The pressure exhibits significant uncertainty in the separation region around the head car cab and bogie, as well as in the wake flow region of the tail car. With sensitivity analysis, the drag coefficient Cd is highly uncertain due to the prominent contribution of Cϵ2, which accounts for 68.76% of the uncertainty. Additionally, Cϵ2 and σk are key factors affecting pressure uncertainty, each dominating distinct areas. Finally, the linear regression identifies a strong positive correlation between Cϵ2 and the drag, which could provide guidance for improving the modelling performance by optimizing the turbulence model coefficients. [ABSTRACT FROM AUTHOR]

The climatic wind tunnel (CWT) is widely recognised as the optimal experimental environment for studying vehicle rainwater management, while the rainfall field generated by the CWT for vehicles may differ from the natural rainfall patterns. Therefore, this study aims to provide an approach to ensure consistency between the two rainfall environments by developing a virtual CWT (VCWT) rainfall scenario and a natural rainfall scenario. Two-phase flow computational fluid dynamics (CFD) method is conducted to reproduce the natural and CWT rainfall scenarios. Results of flow and rain fields of simulations are validated with experiment data respectively. Distributions of water film on the body surface and raindrop particles around the vehicle are discussed. The arrangement of rain spraying nozzles is optimised by assessing and analysing the discrepancy between the two rainfall scenarios so that a more rational rainfall environment can be provided in CWT. Improving the spacing and spray direction of nozzles benefits in narrowing the gap between natural and VCWT rainfall scenarios. An efficient approach is proposed in this work to make it possible to achieve the consistency between the rainfall environment in the CWT and the natural rainfall situation, providing an advance for rainwater management of vehicles. [ABSTRACT FROM AUTHOR]

This study focuses on the TM-141 supersonic compressor blade as the subject of investigation. Utilizing the Reynolds-averaged numerical simulation approach, the study examines the impact of the leading-edge sawtooth structure on the blade grid, flow field characteristics, and flow losses. Comparative analysis is conducted between numerical results and experimental data to assess the influence of the leading-edge sawtooth structure under various conditions, including fixed Mach numbers and variable static pressure ratios, fixed static pressure ratios and variable Mach numbers, and fixed Mach numbers and fixed static pressure ratios. The findings reveal that the leading-edge sawtooth structure effectively alters the distribution of total pressure loss coefficients within the blade grid channels, mitigates leading-edge spikes, and improves trailing-edge blade morphology, consequently reducing trailing-edge losses and total pressure loss compared to benchmark blade grids. These results offer insights for mitigating losses and enhancing efficiency in the transonic region of compressor blade operation, thereby providing a foundation for further investigation into the effects of leading-edge sawtooth structures on flow fields. [ABSTRACT FROM AUTHOR]

The large number and dense layout of rail fastening can significantly affect the aerodynamic performance of trains. Utilizing the Improved Delayed Detached Eddy Simulation (IDDES) approach based on the SST (Shear Stress Transport) k-ω turbulent model, this study evaluates the effects of the rail fastening system on the aerodynamic force, slipstream and train wake under crosswind conditions. The results indicate that in such conditions, compared to the model without rails, the rail and the fastening system reduce the drag force coefficient of the train by 1.69%, while the lateral force coefficients increase by 1.16% and 0.87%, respectively. The aerodynamic force can be considered virtually unchanged within the error allowance. However, the rail and the fastening system cause an inward shift of the negative pressure center on the leeward side of the train. The peak slipstream velocity near the ground in the rail and rail fastening system model is significantly lower than that in the situation without rails. Additionally, the rail and the fastening system not only induce two displacements in the vortex structure of the train but also accelerate the dissipation of shedding vortex and the rapid decrease of turbulent kinetic energy. [ABSTRACT FROM AUTHOR]

Abstract Sandstorms have destructive effects on railway infrastructures due to the movement and erosion of sand. One of the proposed solutions to reduce the impact of windblown sand on desert railways is the hump slab track superstructure. This system entails removing the ballast layer and elevating the rails using concrete foundations called humps, which create sand movement channels beneath the rails. The hump’s geometry must not only meet optimal aerodynamic conditions but also ensure ample clearance for sand passage, maintaining structural stability and efficient railway performance. In this study, the aerodynamic evaluation of various hump geometry is examined considering the elliptical (EL) and semicircular-rectangular (CR) shapes. Simulations are carried out using 3D computational fluid dynamics in ANSYS Fluent software. A gas–solid two-phase model, comprising a distinct phase for sand particles and another for air, is developed to assess the sand movement capacity through the selected hump geometries. A wind tunnel experiment is then performed on a prototype of a hump slab track to validate the software model. The findings highlighted that the CR shape, with a height of 25 cm, resulted in the most favorable outputs.

The high-speed movement of trains generates train-induced wind, commonly referred to as slipstream, which presents a specific safety concern for passengers and personnel. Yet, the fastening system employed to secure ballastless tracks, characterised by its complex shape, substantial quantity, and dense arrangement, remains inadequately investigated regarding its influence on train aerodynamics. In the present study, a sliding mesh technique was employed to comparatively examine the impact of different track configurations—trackless, track-only, and track with a fastening system—on the aerodynamic characteristics, slipstream formation, and wake turbulence induced by trains. The results indicate that the tracks and the fastening system increased the drag force coefficient by 0.73% and 2.05%, respectively, compared with no track. Additionally, tracks and the fastening system had a significant impact on the slipstream velocity near the train and ground. Tracks notably altered the shape of the wake near the ground, and the fastening system exacerbated this phenomenon. Further, the fastening system further intensified the generation of secondary vortices at track and footstep locations.

In this research, we delve into the promising potential of horizontal axis wind turbines to effectively meet the electricity needs of developing countries. By addressing the challenges posed by low Reynolds number airflow characteristics, we focus on specific airfoils—E471, S2055, and RG15—tailored for horizontal axis wind turbine blade optimization. Utilizing QBLADE software, we evaluate the lift coefficient, stall angle of attack, and lift‐to‐drag ratio coefficient efficiency of these airfoils across various thickness‐to‐camber ratios. The aerodynamic efficiency of the altered airfoils is assessed in terms of lift coefficient, drag coefficient, lift‐to‐drag ratio coefficient, and stall angle of attack at Reynolds number ranging from 50,000 to 500,000. The findings reveal that the optimized thickness‐to‐camber ratio results in peak lift‐to‐drag ratio coefficient values surpassing the reference airfoils across the Re range. These lift‐to‐drag ratio coefficient enhancements vary among airfoils and Re values. Furthermore, modifications to the E471, S2055, and RG15 airfoils increase the peak lift coefficient and stall angle of attack values across all Re ranges examined. The validation of results is achieved through comparison with experimental testing, solidifying the reliability of QBLADE software in predicting aerodynamic performance. [ABSTRACT FROM AUTHOR]

Micro wind power generation through vertical axis wind turbines for low wind velocity in the department of Santander, Colombia, is viable due to the physical characteristics of the region. However, there are crucial factors for the development of a turbine for the region such as turbine typology, robustness, aspect ratios, etc. For this reason, it is a good practice to perform simulations through computational fluid dynamics (CFD) to predict the performance of the turbine in operation. In this context, an analysis of six configurations of a Darrieus-type VAWT turbine with the asymmetric profile DU06W200 and straight blades, which were obtained by an algorithm considering the factors mentioned above was carried out. The height-diameter ratios to be analyzed were 0.25 (with chord lengths of 0.117 and 0.173 m), 0.4 (with chord lengths of 0.0929 and 0.137 m) and 1 (with chord lengths of 0.0587 and 0.0864 m). It can be concluded that with a ratio of 0.25 and a rope length of 0.173 m, it is possible to obtain an average Power Coefficient of 0.31, which is an outstanding value due to the low wind velocity of the region of interest. [ABSTRACT FROM AUTHOR]

Cable-stayed bridges with box girders are essential innovations in civil engineering, especially for long-span structures. These bridges, reinforced with prestressed cables and box girders, are designed to handle significant loads but remain vulnerable to aerodynamic forces, particularly wind. The vulnerability is measured using the Pb parameter, as defined by the Ministry of Public Works (2015), which helps determine the windbreak structures needed for stability. This study analyzes the aerodynamic stability of bridge decks with widths of 8 m, 13 m, and 19 m on a 420 m bridge, featuring a 220 m main span and two 100 m side spans. The results reveal that the larger the deck width-to-span ratio, the higher the structure's natural frequency, which improves stability. The natural frequency values were recorded at 0.3 Hz for a 7 m deck (3.2%), 0.43 Hz for a 12 m deck (5.48%), and 0.53 Hz for an 18 m deck (8.2%). The most stable span ratio was found with the 18 m deck, with a Pb value of 0.04, showing minimal wind load effects. Moreover, a larger deck width enhances aerodynamic stability and extends the bridge's service life by reducing damage risk from wind loads. [ABSTRACT FROM AUTHOR]

This study investigates the potential of an optimized combination of active nose droop and active Gurney flap (CADAG) in a new flow control strategy to manage dynamic stall over a pitching blade section under variable Mach number flow. The optimization method employs the genetic algorithm coupled with a computational fluid dynamic (CFD) solver and artificial neural network. The base blade section belongs to a section positioned at r/R=0.865 of the rotor blade of the UH-60A helicopter in forward flight condition. A high relative angle of attack on the retreating side makes the flow susceptible to dynamic stall. A nose droop is employed to control the dynamic stall of the blade section, and a Gurney flap is used to maintain the balance of the generated lift of the blade during 360° of rotation. A comprehensive investigation is performed to determine the most significant parameters affecting the performance of the present combined active flow control. The ratio of the total generated lift to the drag is chosen as the objective function of the optimization. Results show that this ratio and the total generated lift in one rotation cycle increase by 193% and 13%, respectively, at the optimum condition of the present combined active flow control, while the ratio of the generated lift over the advancing side to the retreating side is equal to that of the base blade section. In addition, the dynamic stall hysteresis loop reduces significantly, and the maximum value of the drag coefficient and the negative aerodynamic damping decrease up to 87% and 83% compared to the base blade section, respectively. In general, the proposed innovative combined active flow control is an adjustable method to alleviate dynamic stall and improve the aerodynamic performance of rotary wings in different operation conditions. Practical Applications: The rotary blades are extensively used in rotorcraft, turbo engines, and wind turbines. Despite their massive use, they suffer from some essential issues, of which the most important one is the so-called dynamic stall. Dynamic stall is a complex phenomenon that limits the performance of the rotary blades. Due to the physics governing a rotary wing, such as a helicopter rotor blade, dynamic stall and flow separation are very common. Understanding dynamic stall physics and providing solutions to prevent it is still one of the main challenges of aerodynamic scientists. The present study introduces a novel adjustable method for practically alleviating the dynamic stall on helicopter blade section in forward flight conditions to improve its aerodynamic performance in different operational conditions. A comprehensive investigation is carried out to determine the key parameters affecting the proposed method. These findings can serve as a valuable tool for other researchers to develop various active flow control strategies. This article applies an optimization process using artificial neural networks, genetic algorithms, and CFD tools, which forms a comprehensive framework that can be easily extended to other applications. [ABSTRACT FROM AUTHOR]

ABSTRACT Notwithstanding the abundance of different expository efforts by the engineers and scientists of the aerodynamic—transonic domain for the ever‐beseeched question of whether a supercar needs a rear spoiler or a rear wing, the query requires further exploration to come to any satisfactory conclusion. This state‐of‐the‐art bottleneck area is considered as the prime motivation of the paper as it seeks to investigate the aerodynamic phenomena of a notchback type supercar configuration with two different series of modifications—one with a rear spoiler attachment and the other one with a rear wing attached. A simplified Nissan Skyline GT34R CAD model is taken as the base ground vehicle for the computational study while the slant angles of both the rear wing and rear spoiler are changed within the range of 10° to 45°. RANS based k‐omega SST turbulence model is used to find the optimal slant angles for the corresponding rear wing and spoiler in terms of drag and lift coefficients, drag and lift force and rolling moment. The modified models with optimally slanted rear wing and rear spoiler along with the base configuration are inspected under different visualization techniques for understanding the aerodynamic phenomena. Contour and vector plots reveal that rear wing attached model has the maximum pressure drop along and over its body showing a sharp increase of 13.7% when compared with the rear spoiler attached model. Aftereffects show that both the turbulent intensity and Y+ wall shear stress is found to be most economical for the rear spoiler attached model, approximately 1.52% and 0.98% less than the base notchback model. Considering, overall aerodynamic performance of all the three proposed notchback type supercar configurations—the one with a rear spoiler attachment is found to be the most equipped one to integrate into future research.

Countries around the world are spending a lot of social costs due to various social problems such as traffic congestion, housing, and living environments caused by urbanization. It is judged that it is urban air mobility (UAM) that can solve these problems, so each country and local government are actively participating in the UAM industry to solve these problems. And it is promoting it to the public with a blueprint as the best alternative that can dramatically solve the congested traffic environment in the city center. However, I don’t think it explains in detail the many limited operating environments and risks to be overcome in order to commercialize UAM. Therefore, I would like to consider the low-altitude airspace operating environment and vertical take-off landing aerodynamic limitations required for stable commercialization of UAM aircraft.

The trapped-vortex combustor (TVC) is an alternative combustor design to conventional aeroengine combustors. The separate fuel and air injection of this combustor and its compact design make it a perfect candidate for conventional fuel usage. Moreover, the performance of a trapped-vortex combustor with alternative fuels such as ammonia and hydrogen in the actual operating conditions of an aeroengine is not well understood. The present paper focused on the performance evaluation of TVCs with the futuristic fuels ammonia and hydrogen including under the realistic operating conditions of a combustor. The investigated fuels were injected into a cavity with 0-,15-, 30- and 45-degree transverse-angled air injectors to evaluate the mixing enhancement of the air and fuel under idle and low-power conditions. The mixing behavior of hydrogen showed a significant difference from the conventional fuel, i.e., propane. It was also noticed that the transverse injection of the air helped to improve the mixing efficiency as compared to the normal injection configuration. Mixing efficiency was higher for the 30- and 45-degree transverse-angled air injectors compared to the 0- and 15-degree transverse-angled air injectors.

Countries around the world are spending a lot of social costs due to various social problems such as traffic congestion, housing, and living environments caused by urbanization. It is judged that it is urban air mobility (UAM) that can solve these problems, so each country and local government are actively participating in the UAM industry to solve these problems. And it is promoting it to the public with a blueprint as the best alternative that can dramatically solve the congested traffic environment in the city center. However, I don’t think it explains in detail the many limited operating environments and risks to be overcome in order to commercialize UAM. Therefore, I would like to consider the low-altitude airspace operating environment and vertical take-off landing aerodynamic limitations required for stable commercialization of UAM aircraft. [ABSTRACT FROM AUTHOR]

The trapped-vortex combustor (TVC) is an alternative combustor design to conventional aeroengine combustors. The separate fuel and air injection of this combustor and its compact design make it a perfect candidate for conventional fuel usage. Moreover, the performance of a trapped-vortex combustor with alternative fuels such as ammonia and hydrogen in the actual operating conditions of an aeroengine is not well understood. The present paper focused on the performance evaluation of TVCs with the futuristic fuels ammonia and hydrogen including under the realistic operating conditions of a combustor. The investigated fuels were injected into a cavity with 0-,15-, 30- and 45-degree transverse-angled air injectors to evaluate the mixing enhancement of the air and fuel under idle and low-power conditions. The mixing behavior of hydrogen showed a significant difference from the conventional fuel, i.e., propane. It was also noticed that the transverse injection of the air helped to improve the mixing efficiency as compared to the normal injection configuration. Mixing efficiency was higher for the 30- and 45-degree transverse-angled air injectors compared to the 0- and 15-degree transverse-angled air injectors. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANN), an Artificial Intelligence (AI) technique, are both bio-inspired and nature-inspired models that mimic the operations of the human brain and the central nervous system that is capable of learning. This paper is based on a system that optimizes the performance of an uncertain unmanned nonlinear Multi-Input Multi-Output (MIMO) aerodynamic plant called Twin Rotor MIMO System (TRMS). The pitch and yaw angles which are challenging to control and optimize in practice, are being used as the input to the Nonlinear Auto-Regressive with eXogenous (NARX) model, and eventually trained. The training features use the Matlab Deep Learning Toolbox. The NARX structure has its core in the neural networks’ architecture. Data is collected from the TRMS testbed which is used to train the network. ANN as a Hybrid intelligent control strategy of ANN in combination with Pattern Search and Genetic Algorithm, is then utilized to optimize the parameters of the neural networks. At the end it was validated, tested and the optimized system run in simulation and compared with other intelligent and conventional controllers, with the proposed controller outperforming them, giving a very fast tracking control, stable and optimal performance that satisfactorily met all our design requirements.

Trains are a very important mode of transportation for freight and passengers in Indonesia. This encourages PT KAI, which is a train operator in Indonesia, to improve its performance. Currently PT KAI uses several types of locomotives. CC201 locomotives made in 1977-1978 and CC203 made in 1995 are locomotives that are still widely operated. Fuel consumption is one of the components of train operating costs, the percentage of which reaches more than 30%. Railroad fuel consumption is strongly influenced by various factors, one of which is the aerodynamic performance of the locomotive. This study presents an evaluation of the aerodynamic performance of CC201 and CC203 locomotives. The research stages include direct measurement of locomotive geometry and dimensions, CAD drawing creation using SoildWorks and aerodynamic evaluation using ANSYS software. The simulation results show that the flat front design of the CC201 locomotive has greater aerodynamic resistance. This can be seen from the pressure contours and turbulence around the locomotive body. This causes the drag force of the CC201 locomotive to be 44% greater than that of the CC203 locomotive. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Flapping-wing micro air vehicles (FWMAVs) have gained much attention from researchers due to their exceptional performance at low Reynolds numbers. However, the limited understanding of active aerodynamic modulation in flying creatures has hindered their maneuverability from reaching that of their biological counterparts. In this article, experimental investigations were conducted to examine the effect of the bilateral amplitude asymmetry of flexible flapping wings. A reduced bionic model featuring bat-like wings is built, and a dimensionless number Δ Φ * is introduced to scale the degree of bilateral amplitude asymmetry in flapping motion. The experimental results suggest that the bilateral amplitude–asymmetric flapping motion primarily induces maneuvering control forces of coupling roll moment and yaw moment. Also, roll moment and yaw moment have a good linear relationship. To achieve more efficient maneuvers based on this asymmetric motion, it is advisable to maintain Δ Φ * within the range of 0 to 0.4. The magnitude of passive pitching deformation during the downstroke is significantly greater than that during the upstroke. The phase of the peak of the passive pitching angle advances with the increase in flapping amplitude, while the valleys lag. And the proportion of pronation and supination in passive pitching motion cannot be adjusted by changing the flapping amplitude. These findings have important practical relevance for regulating turning maneuvers based on amplitude asymmetry and help to understand the active aerodynamic modulation mechanism through asymmetric wing kinematics. [ABSTRACT FROM AUTHOR]

Hypersonic flight is of extreme interest today because of a new vehicle concept designed to fly at very high Mach numbers. In hypersonic flows, strong shocks are generated with a thicker boundary layer around the surface of flights. In hypersonic flows, nose bluntness for the leading edges of the aerofoil is extremely useful for maximum lift to drag ratio to reduce aerodynamic heating. In hypersonic flows, space between the blunt body nose and the shock generated is mixed subsonic and supersonic flow through the sonic line. The only CFD method available today is the time marching method, as the unsteady equations of motion are hyperbolic with respect to time regardless of whether the flow is locally subsonic or supersonic. ANSYS ICEM CFD is used for meshing two and three-dimensional models as it is having a powerful blocking method. Fluent was used as a solver and postprocessor. A computational study of flow around a power law body was conducted for a Mach number of 8.2, pressure = 951.5 N/m2, temperature = 89.3 K and velocity = 1553 m/s. The Mach number contours obtained were close to experimental values. Coefficient of Drag (CD), Coefficient of Lift (CL) and Coefficient of Moment (CM) obtained were matching to the experimental results. [ABSTRACT FROM AUTHOR]

The Coronavirus Disease 2019 (COVID-19) is an ongoing global pandemic and wearing face mask is recommended across the globe to break the transmission chain of infection. The masks available in the market are of different types and materials and tend to alter the voice characteristics of the speaker. This can therefore impair optimal communication and the present study is a systematic review exploring the effect of various masks on voice production parameters. Systematic review. The titles and abstracts screening was carried out for the inclusion of articles using eight electronic databases spanning the period from 1st January 2020 to 30th April 2021. 10 articles (8 published & 2 in pre-print) that met the inclusion criteria were considered for this systematic review and the pooled age range was 18 –69 years. Three primary studies from the USA, 2 each from Australia & Italy, one each from Brazil, China, and Germany were found to have investigated the influence of wearing N95, KN95, surgical and fabric masks on voice related measures. The users significantly reported vocal fatigue, discomfort, and also perceived voice problems. Attenuation of speech sound amplitude was highest for the transparent mask followed by cloth mask, N95, KN95, and surgical mask. The World Health Organization (WHO) has been repeatedly endorsing the need to use a face mask in the current COVID-19 pandemic. However, for an unintruded voice production, the surgical mask is recommended for everyone, including healthcare professionals when they are not in close contact with patients, and not involved in aerosol-generating procedures. For teachers, doing direct teaching (offline classes), 'surgical mask' can reduce the vocal load of teachers, smoothen the teacher-student interaction and thereby facilitate better learning by the students. Additionally, it would be useful to protect oneself from the risk of developing voice problems by following standard vocal healthcare tips. [ABSTRACT FROM AUTHOR]

Whole-body cryotherapy (WBC) is a therapeutic practice involving brief exposure to extreme cold, typically lasting one to four minutes. Given that WBC sessions often occur in groups, there is a hypothesis that cumulative heat dissipation from the group significantly affects the thermo-aerodynamic conditions of the cryotherapy chamber. Computational fluid dynamics (CFD) is employed to investigate thermal exchanges between three subjects (one man, two women) and a cryotherapy chamber at −92 °C during a 3-minute session. The investigation reveals that collective body heat loss significantly influences temperature fields within the cabin, causing global modifications in aerodynamic and thermal conditions. For example, a temperature difference of 6.7 °C was calculated between the average temperature in a cryotherapy chamber with a single subject and that with three subjects. A notable finding is that, under an identical protocol, the thermal response varies among individuals based on their position in the chamber. The aerodynamic and thermal characteristics of the cryotherapy chamber impact the heat released at the body's surface and the skin-cooling rate needed to achieve recommended analgesic thresholds. This study highlights the complexity of physiological responses in WBC and emphasizes the importance of considering individual positions within the chamber for optimizing therapeutic benefits. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANN), an Artificial Intelligence (AI) technique, are both bio-inspired and nature-inspired models that mimic the operations of the human brain and the central nervous system that is capable of learning. This paper is based on a system that optimizes the performance of an uncertain unmanned nonlinear Multi-Input Multi-Output (MIMO) aerodynamic plant called Twin Rotor MIMO System (TRMS). The pitch and yaw angles which are challenging to control and optimize in practice, are being used as the input to the Nonlinear Auto-Regressive with eXogenous (NARX) model, and eventually trained. The training features use the Matlab Deep Learning Toolbox. The NARX structure has its core in the neural networks' architecture. Data is collected from the TRMS testbed which is used to train the network. ANN as a Hybrid intelligent control strategy of ANN in combination with Pattern Search and Genetic Algorithm, is then utilized to optimize the parameters of the neural networks. At the end it was validated, tested and the optimized system run in simulation and compared with other intelligent and conventional controllers, with the proposed controller outperforming them, giving a very fast-tracking control, stable and optimal performance that satisfactorily met all our design requirements. [ABSTRACT FROM AUTHOR]

Efficient implementation of clean energy technologies is paramount, with mobile solar PV systems on trailers (MSPTs) emerging as pivotal solutions, particularly in regions with limited power grid access. This endeavour is vital for meeting escalating electricity demands and aligning with the UN Sustainable Development Goal (SDG), aimed at ensuring dependable and sustainable energy provision in developing countries. This study investigates the aerodynamic behaviour of a designed MSPT using numerical simulation and experimental methods, thereby offering optimization potential for MSPT design and enhancing overall performance and reliability. Specifically, the study focuses on the effects of wind velocity and tilt angles on the drag and lift forces, as well as drag and lift coefficients on the panel used in the MSPT system. The overall wind force on the entire MSPT, including nine large solar PV panels, is scrutinised, considering combined wind flow and system geometry effects. The numerical investigations were conducted using ANSYS-Fluent software (version 2022/R2) and experimental testing was performed within the C15-10 Wind Tunnel, utilizing scaled-down models to validate the accuracy of the simulation. The findings from the numerical investigations showed an increased turbulence caused by gaps between panels, resulting in almost 62% higher suction flow velocity and 22% higher suction pressure compared to a single panel. Drag and lift forces on the entire MSPT were approximately 6.7 and 7.8 times greater than those on a single panel with the same 30-degree tilt angle, respectively. The findings revealed that scaling forces on a single panel is insufficient for accurately predicting the aerodynamic forces on the entire MSPT. The insights and the knowledge from this study pave the way for further improvements in mobile solar PV technology. [ABSTRACT FROM AUTHOR]

Several ten-stages-compressor of a high bypass ratio turbofan engine was used as the research object, the change law of tip clearance and its effects on aerodynamic performance and stable boundary of the compressor were investigated based on a high speed compressor component, core engine and complete engine test facility. The mechanism and the sensitive area of tip clearance effect on the overall performance and each stage performance of multistage compressors was revealed by detailed simulation results of transonic and subsonic stage performance. The results show that the clearance change law of compressors of different sizes is consistent, which is mainly related to centrifugal force and temperature filed. Flow-pressure ratio and flow-efficiency characteristics of the compressor at design rotational speed Indicate a feature of whole reduction while the clearance increases, and the clearance has more impact on the back subsonic stage. With the increase of the tip clearance, the efficiency of the front transonic stages of the compressor does not decrease for the small ratio of clearance to the big blade height, but the work capacity of the back subsonic stage decreases obviously, and the influence of the clearance mainly concentrates on the back subsonic stage, which makes the compressor efficiency and stall margin droop. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)