Airflow Control Research Articles

A new tool for energy conservation in operating room: The role of machine learning models in enhancing airflow control

Maintaining high ventilation rates in operating rooms (ORs) is critical to ensure the safety of healthcare professionals and patients. Yet, the significant energy consumption associated with ventilation systems is a growing global concern. While traditional approaches have predominantly focused on optimizing ventilation design, limited attention has been given to operational control strategies. This study aims to control ceiling air supply speed by exposure aerosol concentrations exhaled by the patient. It achieves this by integrating empirical data with machine learning (ML) models, effectively balancing the need for maintaining optimal ventilation conditions and ensuring a safe aerosol exposure concentration. Experimental results from a full-scale OR setup, manipulating ceiling air supply speed, respiratory flow rate, and surgical bed height, generated 81 datasets. These datasets served as the basis for assessing the performance of 11 ML models. Notably, the extra trees (ET) and multi-layer perceptron (MLP) models outperformed the others, exhibiting impressive coefficient of determination (R2) values of 0.954 and 0.904, respectively. Moreover, the models were further enhanced by assessing their robustness with Gaussian noise and interval prediction. This study presents a novel approach that holds significant relevance for the practical control of ventilation systems, particularly with regard to health and energy efficiency considerations.

Intelligent control of electric vehicle air conditioning system based on deep reinforcement learning

The existing AC system of EVs consumes a lot of energy in summer, resulting in reduced range. Additionally, the cabin temperature (Tcabin) fluctuates due to varying driving conditions. In this paper, an innovative cooling strategy is designed to address the above drawbacks using deep reinforcement learning algorithms. The primary objective of this strategy is to achieve high-precision temperature control while concurrently minimizing the energy consumption of the AC system. The strategy combines compressor speed (Ncompressor) and blower airflow (Bairflow) control to optimize the AC system's performance. The RL controller minimizes energy consumption by reducing Ncompressor while increasing Bairflow, thus ensuring a constant cooling capacity (Q). And it effectively reduces temperature fluctuations within the cabin. Finally, the RL control strategy was compared with on/off control and proportional integral differential (PID) control. The results showed that RL control performed well in the multi-objective optimization of the AC system. In terms of temperature control, it effectively reduces the amount of overshooting, and the minimum temperature fluctuation achieved through RL control is merely 0.07 °C, exhibiting an 84.4 % and 86.5 % decrease compared to traditional control methods. The average absolute temperature error stands at 0.06–0.07℃, maintaining a remarkable precision in preserving the target temperature. Furthermore, RL control not only ensures superior energy efficiency but also reduces energy consumption by up to 5.98 % and 7.65 % compared with traditional control methods.

Design and Implementation of a Linear Active Disturbance Rejection Control-Based Position Servo Control System of an Electromotive Valve for Exhaust Gas Recirculation.

An exhaust gas recirculation (EGR) valve is used to quickly and dynamically adjust the amount of recirculated exhaust gas, which is critical for improving engine fuel economy and reducing emissions. To address problems relating to the precise positioning of an electromotive (EM) valve under slowly varying plant dynamics and uncertain disturbances, we propose a servo control system design based on linear active disturbance rejection control (LADRC) for the EGR EM valve driven by a limited angle torque motor (LATM). By analyzing the structure of the LATM and the transmission, the dynamic model of the system is derived. In addition, to solve the problems caused by slowly varying plant dynamics and uncertain disturbances, we combine the effects of uncertain model parameters and external disturbances as the total disturbance, which is estimated in real time by an extended state observer (ESO) and then compensated. In addition, accurate angular information is obtained using a non-contact magnetic angle measurement method, and a high-speed digital communication channel is established to help implement a closed-loop position control system with improved responsiveness and accuracy. Simulation and experimental results show that the proposed servo system design can effectively ensure the precision and real-time performance of the EM valve under slowly changing plant dynamics and uncertain disturbances. The proposed servo system design achieves a full-stroke valve control accuracy of better than 0.05 mm and a full-stroke response time of less than 100 ms. The controlled valve also has good robustness under shock-type external disturbances and excellent airflow control capability. The repeatability of the airflow control is generally within 5%, and the standard deviation is less than 0.2 m3/h.

Pneumatic Structural Deformation to Enhance Resonance Behavior for Broadband and Adaptive Radar Stealth.

Ideal radar absorbing materials (RAMs) require instantaneous, programmable, and spontaneous adaptability to cope with a complex electromagnetic (EM) environment across the full working frequency. Despite various material systems and adaptive mechanisms having been demonstrated, it remains a formidable challenge to integrate these benefits simultaneously. Here, we present a pneumatic matrix that couples morphable MXene/elastomer conductors with dielectric spacers, which leverages controllable airflow to reconfigure the spatial structure between a flat sheet and a hemispherical crown while maintaining resistance stability via wrinkle folding and unfolding. The interdimensional reconfigurations drastically induce multiple resonance behavior, enabling the matrix remarkable frequency tunability (144.5%), ultrawide bandwidth (15 GHz), weak angular dependence (45° incidence), ultrafast responsiveness (∼30 ms), and excellent reproducibility (1000 cycles). With multichannel fluidic and conceptual automated control systems, the final pneumatic device demonstrates a multiplexed, programmable, and autonomous transformable mode that builds a promising platform for smart radar cloaking.

Advances and opportunities in wind energy harvesting using plasma actuators: a review

Abstract The dielectric barrier discharge plasma actuator has been recognized as a leading technology for controlling fluid flow and has found remarkable applications in wind energy harvesting over the past decade. Wind turbine aerodynamics are critical in this concept and performance is mainly determined by flow controllers, although significant technical progress is still required. This paper examines all the critical studies to investigate the potential application of plasma actuators for airflow control over wind turbines. This approach has been divided into three categories: wind turbine airfoils, horizontal-axis wind turbines and vertical-axis wind turbines aerodynamic performance and generated power. Finally, the potential functions of plasma actuators in current and future wind turbine generators are discussed. These actuators offer promising solutions to increasing power output, minimizing torque fluctuations and enabling self-starting capabilities, particularly in vertical-axis wind turbines. By adjusting blade pitch angles in conjunction with plasma actuators, significant improvements in airflow optimization and power extraction have been demonstrated. Despite the advancements, challenges persist, such as determining optimal actuator placement and overcoming structural limitations, especially concerning 3D effects and high Reynolds numbers. While plasma actuators enhance aerodynamic efficiency, their complexity needs to be balanced against marginal gains in power production, especially in high-megawatt turbines, for which controlling flow at low wind speeds is challenging. Future research must focus on the sustainable integration of plasma actuators, pitch angle adjustments and active control mechanisms to fully exploit the potential of wind energy for a sustainable future.

Analysis of O3 Pollution Affected by a Succession of Three Landfall Typhoons in 2020 in Eastern China

Based on air quality monitoring, surface meteorological data, wind profile radar observation, and the HYSPLIT model, the characteristics and causes of O3 pollution in eastern China during the period of the typhoons BAVI, MAYSAK, and HAISHEN from August 26 to September 8, 2020 were analyzed. The results showed that during the succession of the three landfall typhoons, the O3 pollution sites in Beijing Tianjin Hebei and its surrounding areas (BTHS) and the Yangtze River Delta (YRD) exceeded 50%. During the HAISHEN period, O3 pollution days in the two regions reached 2.22 d and 2.97 d, respectively, with significant persistence characteristics. The location of the typhoon had an obvious influence on O3 concentration. When the typhoons were located within the 24h warning line, the O3 concentrations in BTHS and YRD were relatively low. When the typhoons were located between the 24 h and 48 h warning lines, the O3 concentration in BTHS was the highest. When the typhoons moved north of 34°N, the YRD was most prone to regional O3 pollution. O3 pollution in Shanghai mainly occurred under the control of the northward air flow to the west side of the typhoons, and the regional transport from the upstream area had a significant impact on the increase in O3 and its precursor concentrations. The downdraft below 1 000 m maintained O3 at a high concentration at night. In Jinan, O3 pollution mainly occurred under the control of the subtropical high and typhoon periphery. The downdraft prevailed in the middle and lower levels during the O3 pollution. From August 28 to 30, under the control of the subtropical high, the pollutants were mainly accumulated locally, and some of them were transmitted within the province, showing a "double high" phenomenon of O3 and PM2.5. From September 5 to 8, under the influence of HAISHEN peripheral circulation, the regional transport was obvious, and the O3 concentration increased earlier than that of PM2.5.

Dynamic analysis of air quality and air flow control mode in residential buildings

Dynamic analysis of air quality and air flow control mode in residential buildings

Evaluation of the operation of the fan of the combine harvester air-and-screen cleaning system when using an asynchronous electric motor as a drive

The article presents the results of a study of a combine harvester fan after making design changes aimed at facilitating air flow control in airand-screen cleaning. To this effect, the mechanical drive of the combine harvester fan was replaced with an electric one having an automated control system based on variable-frequency drive (VFD).

Speech Acoustic Parameters for Predicting Presbyphagia: A Preliminary Study in the Elderly Shanghainese Population

PurposeAge is a high-risk factor for dysphagia. Speech and swallowing share the same anatomical and neurophysiological basis. Their functions are closely related; hence, speech assessment can predict the risk of dysphagia. This study aimed to investigate the factors influencing presbyphagia in a normal elderly Shanghainese population by analyzing speech acoustic parameters. MethodsRelevant speech acoustic parameters were compared between 15 people with dysphagia and 15 without dysphagia. After extracting sensitive speech acoustic parameters related to swallowing, changes in sensitive parameters were compared at different ages to analyze the relevant factors influencing presbyphagia in the normal elderly population. ResultsEight speech acoustic parameters related to swallowing, including maximum phonation time (MPT), max F0, /ʔʌ/Jitter, /ʔʌ/L-DDK, /hʌ/L-DDK, /pataka/DDK, F1/a/, and vowel space area, were extracted after comparing the relevant data between the two groups. Analyzing the changes in each of these parameters between different age groups (age 18–39, 40–64, and 65 and above), we discovered that three speech acoustic parameters, including MPT, /hʌ/L-DDK, and /pataka/DDK, had statistical differences, with a decreasing trend in their mean values with increasing age. ConclusionsThe elderly group had significantly lower MPT, /hʌ/L-DDK, and /pataka/DDK than the young and middle-aged groups. We hypothesized that reduced respiratory support and control, decreased range of mouth movements and coordination, closed control of the vocal cords, and inadequate airflow control in vocal cord abduction are risk factors for presbyphagia in the elderly Shanghainese population.

Training, environmental and nutritional practices in indoor cycling: an explorative cross-sectional questionnaire analysis.

Indoor cycling at home has grown rapidly in recent years facilitated by advances in technology and gamification. However, there is limited data on individual's training practices when cycling indoors. Using a single-time point, cross-sectional questionnaire, we gathered information on equipment, environmental considerations, training practices and nutrition during indoor cycling. Following 492 responses, external variables (weather; 88.4%, lack of daylight; 56.3%), time efficiency (81.9%) and general fitness (70.9%) were most frequently cited as reasons to engage in indoor cycling. "Smart" turbo trainers linked to a mixed-reality cycling software were most frequently reported in equipment set-up. 78% of participants attempted to control temperature with 96% of these participants using at least 1 fan to control airflow. The volume of indoor training differed between seasons (winter: 6h10 ± 3 h 30, summer 2h52 ± 2h57, p < 0.001), and structured (61.9%) and unstructured work-outs (64.7%) were completed more than once a week with fewer participants engaging in competitive/racing events (20.9%). 98% percent of participants consumed fluids with an average fluid intake of 0.74 ± 0.28 L/h. Dependent on type of work-out, participants reported less planning of carbohydrate and protein intake during short-duration work-outs (∼40%-60%) relative to longer-duration work-outs (∼56%-80%). Caffeine use was the most frequently reported ergogenic aid. Together we report indoor cycling practices with respect to training equipment, considerations of environmental and nutritional strategies and training habits. Our findings could be used to support the development of future research and indoor training guidelines.

Pull – in analysis of L – shaped meandered capacitive pressure sensor at ultra low pressures

Pressure sensors in the range of 0 – 100 Pa are used in medical ventilators to monitor and control the air pressure delivered to patients during breathing assistance. They ensure precise control of low-pressure airflow in respiratory support systems. In this paper, an l-shaped meander and circular diaphragm based capacitive pressure sensor is designed and analyzed at ultra-low pressures. The pull – in voltage of the design is evaluated and observed to be 7.34 V where the electrostatic force is observed as 8.2 µN. The deflection of the diaphragm at various voltages less than the pull – in voltage is analyzed by applying the external pressure (measurand) and observed that the impact of electrostatic forces is weak when the driving voltage is less than half of the pull – in voltage.

Futuristic Exploring of Ionic Wind Technology and Wind-Assisted Propulsion in a Comprehensive Journey

This research investigate into the convergence of ionic wind technology and wind-assisted propulsion, presenting a combined approach to enhance propulsion systems in diverse applications. Ionic wind, characterized by electro aerodynamic propulsion, involves the generation of ions through electrostatic fields to induce controlled airflow. Concurrently, wind-assisted propulsion leverages natural wind currents to amplify the thrust of vehicles or devices. Through a systematic investigation, this study aims to unravel the potential benefits, address the associated challenges, and illuminate the synergies emerging from the seamless integration of these innovative propulsion technologies.

CFD modeling of contaminant capture with an air flow control valve in a full-scale kitchen: an experimental and numerical study

CFD modeling of contaminant capture with an air flow control valve in a full-scale kitchen: an experimental and numerical study

Study of highly efficient control and dust removal system for double-tunnel boring processes in coal mines

To reduce coal dust pollution during double-tunnel boring processes in coal mines, an efficient control and dust removal system has been established and studied by combining theoretical analysis, experimental investigations, numerical simulations, and on-site measurements. The self-developed new spiral air curtain generator can quickly form multiple axial and radial dust control air curtains that cover the entire tunnel section. When combined with a wet-type dust removal fan, they form an efficient dust control and elimination system for double-tunnel boring in coal mines. The airflow and dust control effects of the highly efficient dust control and removal system, single press-in ventilation, and ventilation with dust removal fans were compared. The results show that with the proposed system, the dust concentrations in the boring tunnel and supporting tunnel can be controlled within 18 and 15 m distances from the working face, respectively. The dust control efficiency is increased by 82 % and 85 %, respectively. Hence, the dust concentrations in the coal mine are effectively reduced.

Enhancing respiratory physiology education: innovative wet spirometer modifications for hands-on learning.

The use of wet spirometers, although once common, has greatly declined because these devices measure only static lung volumes and students often face technical issues in their use. In this study, the wet spirometer has been modified to investigate the fundamental laws of flow and different types of lung disease. This modification was achieved by changing the dimensions of the device, printing a scale on the bell, and attaching an airflow control system (ACS) between the corrugated tube and hollow tube of the inner cylinder. The ACS allowed for flow control during the exercises. Two exercises were performed: exercise I compared the parameters measured by the wet spirometer, modified spirometer, and computerized spirometer to determine the suitability of the modification, while exercise II tested the variables affecting flow. These exercises introduce students to data collection, analysis, and the use of statistical tests as they compare various spirometers. Additionally, students gain valuable experience in experimental design by conducting diverse experiments that investigate factors influencing flow dynamics. By plotting the results and participating in small group discussions, students can apply flow principles in respiratory and circulatory systems, offering a hands-on experience that integrates physics and physiology. The modified spirometer facilitated multifaceted topic exploration, surpassing the traditional wet spirometer's capabilities.NEW & NOTEWORTHY This activity involves cost-effective modifications to the wet spirometer, broadening its applicability. These modifications effectively address student challenges associated with wet spirometer handling and enhance comprehension of fluid dynamics, all without the need for costly simulations, wet experiments, or fragile instruments. By offering a hands-on experience without traditional limitations, our modified spirometer provides an accessible and engaging approach to respiratory physiology education.

A novel air balancing method based on an improved perceptron under multiple constraints for the energy conservation of ventilation system

Air balancing is a key technology for improving indoor environmental quality and reducing ventilation system energy consumption. Existing air balancing methods just considered damper angles and fan control voltages, combined as single constraint strategy to balance air. Fan power, as the direct parameter affecting system electricity consumption, has not been included in air balancing modelling. On the other hand, single constraint strategy makes current methods inflexible to maintain airflow accuracy and energy efficiency together. This paper proposes a novel air balancing energy-saving model with multiple constraint control strategy. Damper angle, fan control voltage, and fan power are combined by an improved perceptron model. It is aimed at minimizing ventilation system energy consumption, by achieving optimal airflow accuracy and energy conservation. The proposed improved perceptron under multiple constraints (IPMC) method is validated on the experimental system with 5 terminals, air balancing relative errors within 6.0 %. Compared with the current high-precision and energy-saving methods in references, IPMC reduces energy consumption by 12.0 % and 7.6 %, respectively, with improved airflow prediction accuracy. The proposed air balancing method has three innovation: 1) Constrained by the fan power, the IPMC method improves ventilation energy efficiency; 2) Independent and flexible constraints enable more accurate airflow control; 3) Integrated by an improved perceptron, multiple constraints consider airflow prediction accuracy and energy conservation at the same time. This method is expected to better satisfy airflow demand and reduce effectively energy consumption of ventilation system, thus improving building ventilation energy utilization efficiency without losing thermal comfort and indoor air quality.

Aerodynamic designs in FORMULA ONE cars

To many of us, FORMULA ONE (F1) racing is an expensive sport that requires high-level entry requirements. However, compared to its value for entertainment purposes, the significance of its technological contribution to transportation in all different areas is enormous. This study focuses on understanding the physics and implementation behind aerodynamic designs in modern F1 racing cars. For this purpose, this research is conducted by analyzing the structure of the individual parts and their integrated effects on F1 aerodynamic performance. The result revealed that generating appropriate vortices around the boundary flows and guiding the airflow in an optimized direction can boost the performance of F1 cars. This study emphasizes the importance of utilizing airflow control for maximum maneuverability and might benefit many transportation-related industries.

Numerical study on the thermal fluid of multi-chip test chamber with guide vane

This study describes a possibility for improved temperature uniformity by changing the chamber geometry using guide vane for application in test chambers. For the test chamber used in multi-chip testing, air cooling technology is commonly employed to maintain internal temperature and control the heat generated by semiconductor devices. The air cooling offers advantages such as simplicity of design and cost-effectiveness, however, it has the disadvantage of high dependence on fluid flow characteristics due to the shape of the internal space, making it prone to uneven airflow distribution at different locations. In order to perform especially package testing of semiconductor chips, it is necessary to actively control the target temperature in the test chamber to respond the rapidly changing temperature by heat generation of semiconductor chips. So, the accurate operation is request by the airflow control of test chamber in order to control the temperature of internal heat sources effectively. In this study, we conducted optimization research based on numerical analysis to improve temperature uniformity through efficient operation of airflow control of semiconductor package testing equipment. To analyze the accuracy of numerical analysis, we fabricated a test chamber identical to the analysis model and investigated the correlation between internal heat generation and fluid flow characteristics. It is anticipated that the validated methodology through numerical analysis and experimented research can provide a solution for achieving rapid response in attaining and maintaining the target temperature, which is essential for reducing semiconductor chip testing time to applied in an industrial context.

Experimental and numerical study of adaptive ventilation and sunlight regulation building envelope combining variable transparency shape-stabilized phase change material

The development of adaptive building envelopes with advanced PCM to reduce building energy consumption is a promising topic. This study proposed an adaptive ventilation and sunlight regulation wall (AVSRW) by combining the variable transparency shape-stabilized PCM (VTSS-PCM), reflective film, and ventilation cavity. The combination of VTSS-PCM and reflective film could passively regulate the solar absorptivity (SA) of AVSRW. The ventilation cavity with airflow control enhanced the heat storage and release efficiency of VTSS-PCM. A dynamic photo-thermal coupling model of the AVSRW was presented and validated by a full-scale experiment in summer and winter conditions. Then, based on the weather data of the typical meteorological year of Changsha, China, the performances of AVSRW on days, months, and a year were evaluated. The impact of three influential factors and their combined effects on the performance of AVSRW were analyzed. Ultimately, a global optimization was conducted to improve the performance of AVSRW, and compared with the massive wall. The results showed that the AVSRW passively decreased its SA on summer days and increased its SA on winter days. The total annual undesired heat exchange (TAHE) of AVSRW first decreased and then increased with the increase of melting temperature (Tm) and thickness (L) of VTSS-PCM. The reflective film had an opposite effect on the annual heat gain (AHG) and annual heat loss (AHL) of AVSRW, resulting in the TAHE remaining unchanged with the increase of reflectivity (R) of the reflective film. The greater the L, the smaller effect of the Tm and R on the AHG and AHL, and the greater the R, the greater effect of the Tm and L on the AHG and AHL. After optimization, the values of the Tm, L, and R corresponding to the optimal solution were 24.60 °C, 0.17 m, and 0.63, respectively. Compared with the reference wall, the AVSRW with the best performance had lower AHG and AHL, and the annual energy-saving rate of the AVSRW reached 43.49%. This study guides the application and parameter optimization of AVSRW in hot summer and cold winter regions.

Numerical modeling of non-uniform indoor temperature distribution for coordinated air flow control

The indoor thermal environment is usually non-uniformly distributed in parameters such as temperature and velocity. For precise control of indoor environment, it is necessary to figure out the indoor non-uniform temperature distribution (INUTD) that empowers independently zone control according to the different requirements of occupants. Computational Fluid Dynamics (CFD) tool is usually used to obtain the INUTD, but it consumes huge computational resources and time, which may not be suitable for coupling with control system. To address this research question, this study proposes a numerical modeling method for predicting the INUTD and air flowrate response of multiple diffusers for coordinated air flow control. Firstly, we establish a dataset with 5000 cases, along with the results of INUTD for each case. Then two models, namely room thermal response model (RTRModel) and air flowrate prediction model (AFPModel), are developed by machine learning algorithms to predict indoor temperature and supply air flowrate, respectively. The results show that proposed models are both fast in prediction, less than 1 s for each case. The standard deviation of error in RTRModel developed with support vector machine algorithm is 0.0041 while that in AFPModel developed with Convolutional Neural Network algorithm is 0.0198. Further, a comparative analysis has been conducted between the AFPModel with and without optimization algorithm. The results reveal that using optimization algorithm is more accurate, but it takes more time. While numerical modeling can instantaneous response with qualified accuracy. The proposed method can contribute to independently zonal environment control and occupant-centered micro-environment control.