Air Volume Research Articles

Airflow Characteristics in Conveyor Type Damper for Hot Air Temperature Changes

The aim of this study was to present the characteristics of a hot airflow in a conveyor type dampers under the hot air temperature changes. The amount of space occupied by the damper was reduced by 50 %, and by efficiently managing the damper's airflow rate even in the face of extreme external conditions and constant air volume proportional control, a conveyor-type damper with a significant energy-saving effect has been explored. It was configured to control the degree to which it was opened by operating the folding conveyor drive mechanism, enabling the damper to modify airflow. In this study, the mass flow rate of heated air through the conveyor-type damper increased in proportion to the damper port's expansion. The mass flow rate of air decreased as the temperature of air intensified. In addition, the thermal energy of the air flowing in the conveyor-type damper improved in ratio to the increase in the damper opening. The findings indicate a 50 % reduction in the damper's occupied space, indicating a significant energy-saving impact of the conveyor-type damper. This is because the damper's air volume is effectively controlled even in the face of severe external conditions, as it is proportionately controlled throughout. The understanding of the properties of airflow for the hot temperature change is strengthened by this research. Furthermore, this study may provide useful direction for future research and industry optimization.

Effects of sand grain roughness height on the performance of wind turbine blade section under extreme weather conditions

Wind turbine blades are prone to icing and their performance is affected significantly by the roughness caused by icing and erosion. Numerical models are constructed to simulate the effects of sand grain roughness on the mass of accreted ice and aerodynamic performance. The sand grain roughness height is considered by applying the NASA and Shin et al. models, and the cloud characteristics studied are the liquid water content (LWC), median volume diameter (MVD) and air temperature covering freezing drizzle and in-cloud icing conditions resulting in glaze ice and rime ice, respectively. The numerical model applied the multi-shot approach, and the effects of the number of shots on the ice accretion and aerodynamic performance was examined to determine the optimum number of shots which can be used in the simulation in order to minimize the computational time without affecting the accuracy. The relationship between the sand grain roughness height and aerodynamic performance is studied, revealing that the shallowest roughness heights cause less performance degradation. The mass of ice increases with increasing LWC from 0.05g/m3 to 0.3g/m3 and MVD from 20 µm to 100 µm, which results in a reduction in the lift-to-drag ratio (CL/CD).

Dosimetric impact of variable air cavity within PTV for rectum cancer.

The aim of this study is to determine the impact of rectal air volume changes on treatment plan quality, and subsequently inform daily cone-beam computed tomography (CBCT) evaluation constraints, in terms of acceptable rectal air volume during treatment. Twelve rectal cancer patients who exhibited rectal air within the PTV on their planning CT were selected. A study was conducted to evaluate the deterioration in plan quality due to expanding air volume. For each case, the air cavity volume was isotropically expanded in three dimensions using predefined margins of 3, 5, 7, and 10mm, while deforming bladder and rectum contours. A constraint was applied to the bony anatomy to restrict the deformation. Treatment plans were then generated for all twelve patients by recalculating the reference plan with the expanded air cavity volume. As the air cavity expanded, the maximum relative change in D98% coverage, compared to the reference plan, decreased by 10.8%±3.5%, while the D2% increased by 3.5%±0.9%. The positioning of the air cavity notably influenced the D98% variability with the 3mm expansion. D98% coverage falls below 95% when the air cavity volume exceeds 17 cm3. On average, D2% coverage increased by 0.5% with each expansion. At the largest expansion, extensive coverage of 102% and 105% isodoses was observed compared to the reference plan. Air cavity volumes above 17 cm3 can potentially degrade the high-dose PTV coverage while increasing the regions covered by the 102% and 105% isodoses. Clinical CBCT guidelines were deduced, recommending a maximum threshold of 3.2cm in diameter in any direction.

Numerical simulation and experimental study of the influence of disk groove structure optimization on the air film flow field signature of an air-cushion sandwich belt conveyor

A new type of disk groove mechanism was developed and manufactured. The effects of the structural and operating factors of the disk groove on the air film loading performance were examined using single factor and orthogonal experimental methods. The results of numerical simulation and experimental studies showed that the air film loading performance correlated positively with the orifice diameter and inlet pressure, with the orifice spacing and diameter having the most significant effects, and that the belt speed boosted the air film uniformity. Meanwhile, a comparative analysis of the corresponding level values showed that an air film thickness of 0.8 mm, orifice diameter of 5 mm, orifice spacing of 30 mm, inlet pressure of 8000 Pa, and conveyor speed of 5 m/s were the optimal parameter combinations for the maximum loading capacity. To verify the accuracy of the model, a field experiment was conducted at Jiangmen Southern Conveying Machinery Engineering Co., Ltd. The air film pressure at the experimental position matched the numerical simulation results. In addition, when the number of rows was one and the air volume was 10 m3/h, the smallest value of traction resistance was obtained under minimum power consumption.

EXPERIMENTAL INVESTIGATION AND CFD SIMULATION OF THE ORIFICE FLOW METER TO MEASURE TWO-PHASE FLOW

In this study, an investigation is conducted to examine various methods for measuring the two-phase flow of water and air. The two-phase flow loop and its equipment, including the orifice flow meter, were designed and manufactured in accordance with relevant standards. By employing the orifice flow meter in the two-phase flow loop and determining the total mass flow rate of the two-phase flow passing through it, the pressure drop of the orifice flow meter was determined for different values of the flow rate and volume fractions of the water and air phases in the two-phase flow. The Reynolds number of the two-phase flow ranged from 700 to 11000, while the air volume fraction ranged from 10% to 45%. We observed that, for the orifice flow meter, the slope of the discharge coefficient variation in relation to the two-phase flow Reynolds number was higher at low Reynolds numbers, where a laminar flow pattern was established. As the two-phase flow Reynolds number increased, the flow pattern transitioned from laminar to plug flow, resulting in a decrease in the slope. The orifice flow meter under two-phase flow conditions was simulated using computational fluid dynamics (CFD) with different turbulence models. The results indicated that the k-epsilon RNG turbulence model yielded more accurate results compared to other turbulence models. This study provides a foundation for the measurement of two-phase flows in the oil and gas industries.

Optimizing patient safety: Unveiling the significance of cuff pressure in anaesthesia

BackgroundInadequate pressure in the endotracheal tube (ETT) cuff can lead to compromised ventilation or airway injury. Accurate assessment of ETT cuff pressure is essential and should be performed using a manometer, with an optimal target range of 20–30 cmH2O. AimIn this study, we aimed to audit ETT cuff pressures in the operating theatre of our institution, utilizing a manometer from VBM Medizintechnik GmbH™. MethodsFollowing approval from the ethics committee, we conducted an audit from January 2023 to November 2023. A convenience sample was utilized, including adult patients who were intubated in our operating rooms (ORs) during either the morning or afternoon shifts at the time of the audit. ResultsA total of 49 patients were evaluated. Our findings revealed that 78 % of the patients had cuff pressures outside the recommended target range, with recorded pressures ranging from 18 cmH2O to 120 cmH2O, and a mean pressure of 63 cmH2O. Nitrous oxide was not used in any of the cases. Cuff inflation was performed using different syringe volumes: a 5 mL syringe was used in one case, a 10 mL syringe in 20 cases, and a 20 mL syringe in 28 cases, with a mean inflation volume of 9 mL. Statistical analysis indicated no significant difference in ETT cuff pressure related to the type of syringe used or the size of the endotracheal tube. Additionally, no correlation was found between the volume of air used for cuff inflation and the resulting ETT cuff pressure. ConclusionOur audit revealed that only 22 % of the patients had cuff pressures within the recommended limits, highlighting a significant need for increased awareness and education. As maintaining appropriate cuff pressure is a standard of care, systematic implementation of reliable cuff pressure monitoring is strongly recommended.

Comprehensive Assessment of Deep-Water Vessel Implosion Mechanisms: OceanGate's Titan Submersible Failure Sequence Explained

This study outlines the physical mechanisms involved in a submersible implosion and analyzes the loss of the Titan submersible (‘sub’) that occurred on 18 June 2023 during a mission to visit the wreck of the Titanic. Titan’s collapse mechanisms at the moment of implosion are described in detail and outer hull fracturing rate, subsequent implosion rate, accompanying heat release and other key processes are quantified. Plausible causes of the hull’s leak leading up to critical loss of the sub's hermetic closure are reviewed using test results made publicly available by the U.S. Marine Board of Investigation. Their data indicated that the bond interfaces between the individual layers of the carbon fiber hull (Hull V2) were critically compromised due to manufacturing defects, voids, porosity, and inadequate adhesive integrity, resulting in significant delamination. Analysis of data from the real-time hull health monitoring system, revealed acoustic anomalies and strain shifts, pointing toward increasing structural fatigue, which went unaddressed prior to the fatal dive. The implosion process can be characterized by an instantaneous collapse of the air volume within the hull under extreme external pressure: even the tiniest leak would lead to destruction of the vessel's structural integrity. The destruction was the more devastating, because it was accompanied by a secondary explosion due to the heat exchange between the collapsing air volume and the ambient sea water. While the collapsing air was phase-changed into a supercritical state, the generated heat caused the adjacent seawater to evaporate and expand. Hull pieces fragmented by the initial implosion were strewn around during the secondary explosion phase, which ceased rapidly as the steam condensed back into seawater once again. The Titan incident underscores the urgent need for improved design standards, rigorous quality control in manufacturing, and enhanced real-time monitoring to prevent similar failures of future deep-sea exploration vehicles.

Unsupervised identification of zone-level anomalies in VAV terminal units utilizing autoencoders and PCA

The effective operation of HVAC systems is crucial to minimize energy inefficiencies and occupant discomfort. However, these systems can experience various problems, including hardware and software-related anomalies. In contrast to most existing fault detection and diagnostic approaches, which rely on simple rules and alarms, this study introduces novel unsupervised approaches for detecting zone anomalies in variable air volume (VAV) air handling units (AHUs). The methods utilize autoencoders (AE) and principal component analysis (PCA). To evaluate the effectiveness of the proposed methods, both a synthetic dataset and measured data from a 28-zone VAV AHU system were investigated. The proposed method successfully detected several zone temperature and airflow anomalies using the AE-based method, and several zone anomalies were also identified using the PCA-AE approach by considering four commonly available zone-level trend logs in VAV AHUs namely temperature, airflow, airflow set-point, and VAV terminal damper position. The findings demonstrated the great adaptability of the proposed methods in detecting a wide range of zone anomalies in any modern building equipped with VAV AHUs, giving operators valuable insights about the system and notifying them of potential faults at an early stage.

Optimizing kitchen ventilation with an integrated stove air supply-exhaust system for reducing PM2.5 intake fraction and enhancing energy efficiency

Ensuring good ventilation is crucial for reducing the pollution caused by cooking activities in the indoor environment. Among them, fume exhaust devices as a vital component of kitchen ventilation, and their performance is particularly critical. Merely increasing the air volume of exhaust devices to remove fumes not only leads to the higher energy consumption of exhaust fans, but also has limited practical effect on reducing pollution. For improving the ventilation condition and reducing the energy consumption of supply and exhaust fan, a new ventilation system for kitchen with integrated stove air supply-exhaust (ISASE) was developed in this study. Firstly, the orthogonal experiment was utilized for arranging different combination schemes of five influencing factors, including the emission rate, exhaust flow, upper air supply angle, upper and lower air supply velocities. Then, the effect of ISASE in reducing the intake fraction of PM2.5 under each scheme was studied by using the computational fluid dynamics method. The energy consumption of this system under different ventilation schemes was investigated with on-site testing. Finally, performance-gaining rate was proposed by introducing intake fraction reduction rate and energy consumption growth rate to quantitatively evaluate the performance advantage of ISASE. Polynomial fitting was also used to explore the energy-saving effect of ISASE at high emission rate. The results showed that at low, medium, and high emission rates, the intake fraction of PM2.5 was reduced by 65.0%–85.2%. However, the energy consumption of ISASE merely increased by 7.4%–16.8% compared with traditional integrated stove without air supply conditions. Its maximum performance-gaining rate reached 0.49–0.66. The energy-saving rate of ISASE was 46.7% compared with traditional integrated stove without air supply when the same intake fraction was achieved at high emission rate. The practical schemes of ISASE at different emission rates were given in this study, which optimized the working performance of integrated stove and provided a useful reference for its innovative design.

Research on the Effect of Deflection Secondary Air on Slagging in Coal Fired Boilers

Abstract In response to the slagging phenomenon in coal-fired boilers, the combustion characteristics of pulverized coal and the effect of deflected secondary air on slagging in a 350MW Corner-tangentially-fired boiler are numerically investigated by the commercial software. The research results indicate that when the deflection secondary air (CFS air) volume increases, the tangential diameter will significantly increase, and the degree of influence is higher than the angle, which has a significant impact on wall temperature and smoke wall brushing. Only adjusting the CFS wind angle or wind volume has a relatively small impact on particle wall brushing; When CFS wind is superimposed with large Angle and high air volume, the temperature and the degree of smoke brushing near the water wall will be significantly increased, and the risk of slag formation on the water wall will be magnified.

Comparing Elastocaloric Cooling and Desiccant Wheel Dehumidifiers for Atmospheric Water Harvesting

Approximately two billion people worldwide lack access to clean drinking water, negatively impacting national security, hygiene, and agriculture. Atmospheric water harvesting (AWH) is the conversion of ambient humidity into clean water; however, conventional dehumidification is energy-intensive. Improvement in AWH may be achieved with elastocaloric cooling, using temperature-sensitive materials in active thermoregulation. Potential benefits, compared to conventional desiccant wheel designs, include substantial reductions in energy use, size, and complexity. A nickel–titanium (NiTi) elastocaloric water harvester was designed and compared with a desiccant wheel design under controlled conditions of relative humidity, air volume, and power. In a 30 min interval, the NiTi device harvested more water on average at 0.18 ± 0.027 mL/WH, compared to the 0.1567 ± 0.023 mL/WH of the desiccant wheel harvester. Moreover, the NiTi harvester required half the power input and was thermoregulated more efficiently. Future work will focus on mechanical design parameter optimization. Elastocaloric cooling is a promising advancement in dehumidification, making AWH more economical and feasible.

ROAD value-based detection for GAE enhanced interference mitigation in LDACS.

The increasing volume of air traffic has placed significant stress on the current Air Traffic Management (ATM) systems, especially concerning the use of Very High Frequency (VHF) communication bands. As air traffic continues to grow, the limitations of the existing spectrum and infrastructure necessitate significant upgrades to ensure safety, efficiency, and capacity. The modernization of air traffic management systems has led to the development and introduction of the L-band Digital Aeronautical Communication System (LDACS), a new communication protocol. LDACS is designed to operate alongside existing L-band systems, ensuring compatibility with legacy users. The coexistence of LDACS with legacy systems poses significant interference challenges, as any disruption in data retrieval can critically impact flight safety. This paper proposes four potential interference mitigation techniques that LDACS can employ to detect and reduce the primary source of interference: Distance Measuring Equipment (DME). The authors introduce a prototype LDACS receiver that uses Rank-Ordered Absolute Differences (ROAD) statistics for effective interference sensing and employs GAE-enhanced pulse peak processors to mitigate Distance Measuring Equipment (DME) interference. Unlike the current GAE-enhanced pulse peak processors, the proposed methods use ROAD value-based detection for identifying DME interference. The performance of the proposed methods - ROAD GAE enhanced Pulse Peak Attenuator (RGPPA), ROAD GAE enhanced Pulse Peak Limiter (RGPPL), ROAD joint GAE enhanced Pulse Peak Attenuator (RJGPPA), and ROAD joint GAE enhanced Pulse Peak Limiter (RJGPPL) is analyzed across different threshold ROAD values to determine their efficacy in various signal conditions. Moreover, the performance of the proposed methods is compared to existing methods such as conventional pulse blanking and GAE-enhanced nonlinear devices, which use the amplitude of the received signal for the detection of interference. Furthermore, the proposed method's performance is compared to another method, ROAD PB, which uses ROAD statistics to detect DME interference and pulse blanking for DME mitigation. The comparative results show that the proposed methods outperformed conventional pulse blanking and ROADPB. Besides, these methods outperformed existing GAE-enhanced methods for their optimum threshold ROAD value.

Investigating dehumidification and heating performance in a dual evaporator heat pump system for electric vehicles

In cold, moisture-rich winter environments, window fogging represents a substantial safety hazard for drivers. Electric vehicles often incorporate heat pump systems to address challenges such as dehumidification and heating specific to cold weather. Therefore, it is essential to evaluate the dehumidification and heating efficiency of these systems through focused research. This study presents a dual-evaporator heat pump system designed specifically for electric vehicles, equipped with two distinct modes for dehumidification and heating. The research examines how factors such as inlet air volume and the degree of opening of the electronic expansion valve affect the system's dehumidification and heating performance. Experimental analyses were conducted to explore the system's response under various conditions of inlet air humidity and compressor speed in both modes. Results suggest that increasing inlet air volume improves dehumidification effectiveness but may reduce heating performance. Likewise, a wider opening of the electronic expansion valve enhances heating but could decrease dehumidification efficiency. Importantly, the study indicates that when the relative humidity of the inlet air exceeds 70 %, a single evaporator mode is more effective for dehumidification. However, when the relative humidity is below 70 %, the dual evaporator mode is more advantageous, showing better heating performance.

Buoyancy regulation in insects.

Multiple insect lineages have successfully reinvaded the aquatic environment, evolving to complete either part or all of their life cycle submerged in water. While these insects vary in their reliance on atmospheric oxygen, with many having the ability to extract dissolved oxygen directly from the water, all retain an internal air-filled respiratory system, their tracheal system, due to their terrestrial origins. However, carrying air within their tracheal system, and even augmenting this volume with additional air bubbles carried on their body, dramatically increases their buoyancy which can make it challenging to remain submerged. But by manipulating this air volume a few aquatic insects can deliberately alter or regulate their position in the water column. Unlike cephalopods and teleost fish that control the volume of gas within their hydrostatic organs by either using osmosis to pull liquid from a rigid chamber or secreting oxygen at high pressure to inflate a flexible chamber, insects have evolved hydrostatic control mechanisms that rely either on the temporary stabilization of a compressible air-bubble volume using O2 unloaded from hemoglobin, or the mechanical expansion and contraction of a gas-filled volume with rigid, gas-permeable walls. The ability to increase their buoyancy while submerged separates aquatic insects from the buoyancy compensation achieved by other air-breathing aquatic animals which also use air within their respiratory systems to offset their submerged weight. The mechanisms they have evolved to achieve this are unique and provide new insights into the function and evolution of mechanochemical systems.

Accelerating the Diagnosis of Pandemic Infection Based on Rapid Sampling Algorithm for Fast-Response Breath Gas Analyzers.

This paper presents a novel technique for extracting the alveolar part of human breath. Gas exchange occurs between blood and inhaled air in the alveoli, which is helpful in medical diagnostics based on breath analysis. Consequently, the alveolar portion of the exhaled air contains specific concentrations of endogenous EVOC (exogenous volatile organic compound), which, among other factors, depend on the person's health condition. As this part of the breath enables the screening for diseases, accurate sample collection for testing is crucial. Inaccurate sampling can significantly alter the composition of the specimen, alter the concentration of EVOC (biomarkers) and adversely affect the diagnosis. Furthermore, the volume of alveolar air is minimal (usually <350 mL), especially in the case of people affected by respiratory system problems. For these reasons, precise sampling is a key factor in the effectiveness of medical diagnostic systems. A new technique ensuring high accuracy and repeatability is presented in the article. It is based on analyzing the changes in carbon dioxide concentration in human breath using a fast and compensated non-dispersive infrared (NDIR) sensor and the simple moving adjacent average (SMAA) algorithm. Research has shown that this method accurately identifies exhalation phases with an uncertainty as low as 20 ms. This provides around 350 ms of breath duration for carrying out additional stages of the diagnostic process using various types of analyzers.

Experimental and simulation study of the effect of temperature and air supply on energy performance of a temperature-controlled ventilated double-layer Trombe wall

To study the energy performance of the temperature-controlled ventilated double-layer Trombe wall system (TCVD-TW) during winter and summer seasons, experiments and simulations were conducted in an experimental room in Qingdao where the system was installed. The experimental results demonstrate that the rooms equipped with this system exhibit favourable temperature performance in both winter and summer, with a positive impact on indoor humidity during the summer. The simulation results show that the performance of TCVD-TW is mainly affected by the supply air temperature, air volume flow rate, and indoor cooling and heating setpoints. For winter operating mode, the optimal supply air temperature setting should be 1°C higher than the heating setpoint. When the supply air temperature was set to 19℃(with a heating setpoint of 18 °C) and 21 °C (with a heating setpoint of 20 °C), the energy efficiency increased by 35.96 % and 32.38 %, respectively. When the supply air volume flow rate was set to 234 m3/h, the energy efficiency increased by 35.09 % (with a heating setpoint of 18 °C) and 30.27 % (with a heating setpoint of 20 °C), respectively. For summer operating mode, the optimal supply air temperature setting should be 1 °C lower than the cooling setpoint. When the supply air temperature was set to 25 °C (with a cooling setpoint of 26 °C), the energy efficiency improved by 33.62 %. When the supply air volume flow rate was set to 156 m3/h, the energy efficiency increased by 31.18 %. The experimental and simulation results of this study provide data support for the application of TCVD-TW.

Atmospheric concentrations of per- and polyfluoroalkyl substances and their emissions at a waste recycling facility producing refuse-derived paper and plastics densified fuel

To better understand the types and concentrations of per- and polyfluoroalkyl substances (PFAS) emitted into the air from waste recycling facilities that produce refuse-derived paper and plastics densified fuel (RPF) from industrial waste, we conducted an air sampling campaign at a waste recycling facility in Japan. Both passive and active air sampling were conducted, and the samples collected were used to quantify the PFAS emitted into the air during the production of RPF. Overall, few ionic PFAS were detected in the air at the facility; however, high levels of neutral PFAS (8.21–53.4 ng/m3; 20.7–130 pmol/m3) were measured in the air near the heat molding machines. The two neutral PFAS detected at the highest concentrations were 6:2 fluorotelomer alcohol and 6:2 fluorotelomer methacrylate, which are currently unregulated under the Stockholm Convention, suggesting that product manufacturers have shifted away from using regulated PFAS. Small amounts of regulated PFAS such as 8:2 fluorotelomer methacrylate and 8:2 fluorotelomer acrylate were measured in some parts of the facility. Analysis of the concentrations of PFAS in the exhaust gas from the heat molding machines revealed neutral PFAS concentrations (537–2160 ng/m3; 1350–5040 pmol/m3) that were 1–2 orders of magnitude higher than those in the surrounding indoor air. The total emission of neutral PFAS from the facility to the environment was estimated to be 0.066–0.260 g/day (0.168–0.607 mmol/day), depending on whether air volume discharged as exhaust gas or as indoor ventilation was considered. A contribution analysis of the emissions revealed that treating the exhaust gas from the heat molding machines, which constitutes over 94 % of the total emissions, is very effective at reducing PFAS emissions from the facility.

Comparative analysis of the influence of different shapes of shaft sections on dust transportation

Large amounts of dust are generated during digging operations in underground mines, and the transportation of dust is affected by the shape of the roadway section. In order to know the dust transportation law of different cross-section shapes when digging. Fluent software was used to simulate the distribution of wind flow field, dust transportation trajectory, and dust quality concentration in roadways with semicircular arch, three-centered arch, rectangle and trapezium, and then analyze and compare the influence of four cross-section shapes on dust transportation, and use gray correlation analysis to investigate the correlation between the time needed to reduce the dust quality concentration of the roadway to the safe value and the ventilation air volume and air supply distance. The results of the study show that the wind speed in the roadway is in the following order from high to low: rectangle &amp;gt; trapezium &amp;gt; three-centered arch &amp;gt; semicircular arch. Dust particles of each size rubbed each other after blasting, and there were fewer dust particles with larger sizes in the three-centered arch roadway. Both the air supply distance and ventilation air volume impact the dust removal effect; when the air supply distances are 5 m and 10 m, the three-centered arch has a better dust removal effect; when the air supply distances are 15 m and 20 m, the effect is better in the rectangular roadway and trapezoidal roadway; and when the ventilation air volume is increased, it is the three-centered arch. Through the gray correlation analysis, it can be seen that in order to improve the construction environment in the roadway after blasting, the rectangular section can be chosen when considering the air supply distance, and the three-centered arch can be chosen when considering the ventilation air volume.

Testing, Validation, and Simulation of a Novel Economizer Damper Control Strategy to Enhance HVAC System Efficiency

Buildings account for over 40% of global carbon dioxide (CO2) emissions, with supply and return fans in air handling units consuming a significant portion of energy. To address this, researchers have explored innovative economizer damper control methods and identified the “split-signal” strategy, which optimizes supply airflow using a single damper as a promising approach. In this study, split-signal was further refined for practical application and energy simulation, aiming to demonstrate its effectiveness and encourage adoption in real-world building mechanical systems. Laboratory testing on chilled water variable air volume (VAV) system showed fan energy savings of 0.2–5% compared to traditional “three-coupled” control, depending on ventilation air proportions, and prevented reverse airflow. A statistical regression model, based on experimental data, was developed to predict energy savings and streamline comparisons. Energy simulations were conducted across various U.S. climate zones and revealed potential savings of 15–20% in energy use, operational costs, and CO2 emissions. With minimal financial investment, split-signal control offers a cost-effective solution to improve energy efficiency and reduce environmental impact, promoting its adoption in real-world building applications.

Treatment outcome of modified endoscopic assisted sinus surgery for treating maxillary sinus diseases with three dimensional volumetric analysis

This retrospective study aimed to analyze volumetric changes of the maxillary sinus after modified endoscopic-assisted sinus surgery (MESS) and to assess short-term treatment outcomes. The volumes of the total maxillary sinus, aeration, and sinus pathology were calculated using computed tomography data obtained prior to surgery and six months after surgery. Postoperative radiological improvement was assessed using the Lund–Mackay score. Bone regeneration around the bony window was evaluated during plate removal. A total of 32 patients were evaluated. Compared with before surgery, air and sinus pathology volumes improved significantly (air, increase by 6.0 cm3, p < 0.001; sinus pathology, decrease by 6.4 cm3, p < 0.001). However, there was no statistically significant change in the total maxillary sinus volume after surgery. The preoperative Lund–Mackay score was 2.9, decreasing to 0.4 six months after surgery (p < 0.001). The only predictors of postoperative aeration rate and Lund–Mackay score were preoperative sinus pathology volume (p = 0.049) and Lund–Mackay score (p = 0.015), respectively. The continuity between the bony window and surrounding sinus wall was restored in all patients. The results of this study suggest that MESS can be a successful, effective, and minimally invasive surgical treatment option for treating maxillary sinus diseases.