Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of...Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments.Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energysaving potential under varying conditions.Results show that increasing the AC setpoint from 25○C to 27○C,combined with ceiling fan operation,reduced power consumption by 10%,achieving significant energy savings.Survey data confirmed that 85%of participants reported consistent thermal sensations across all conditions,with ceiling fans effectively compensating for higher setpoints through enhanced air circulation.CFDsimulations revealed that mediumspeed ceiling fan operation produced the most uniformairflowdistribution,with an average air velocity of 0.45 m/s,and minimized temperature variations,ensuring balanced thermal conditions.Temperature analysis showed a reduction in hotspots and cold zones,maintaining an average temperature deviation of less than±0.5○C.Predicted Mean Vote(PMV)evaluations at a 27○C setpoint indicated improved thermal comfort,with average PMV values around−0.3,corresponding to a“neutral”thermal sensation.These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort,offering a sustainable approach to reducing AC energy consumption in office environments.展开更多
Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely u...Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.展开更多
Numerous investigations have been conducted to understand the wall effects on rotors.The purpose of this study is to further investigate the aerodynamic performance of revolving wings,especially when it is very close ...Numerous investigations have been conducted to understand the wall effects on rotors.The purpose of this study is to further investigate the aerodynamic performance of revolving wings,especially when it is very close to the ground and ceiling(i.e.,less than half the wingspan)at low Reynolds numbers.Hence,the ground and ceiling effect for hovering micro revolving wings at low Reynolds numbers are investigated by improving the theoretical models.The theoretical model for the ground effect is established based on the wall-jet assumption,and that for the ceiling effect is improved by considering the uneven spanwise distribution of induced velocity.These two models are validated by comparing the results of experiments and CFD simulations with the Lattice-Boltzmann Method(LBM).Both ground and ceiling effects are found helpful to enhance the thrust,especially with small wing-wall distances,by making a difference to the induced velocity and the pressure distribution.By comparing the thrust generation and aerodynamic efficiency between the ground and ceiling effects,the former is found more helpful to the thrust augmentation,and the latter is more beneficial for the aerodynamic efficiency promotion.展开更多
In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error acc...In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error accumulation problem in most visual odometry estimation approaches.The principal direction is defned based on the fact that our ceiling is flled with artifcial vertical and horizontal lines which can be used as reference for the current robot s heading direction.The proposed approach can be operated in real-time and it performs well even with camera s disturbance.A moving low-cost RGB-D camera（Kinect）,mounted on a robot,is used to continuously acquire point clouds.Iterative closest point（ICP） is the common way to estimate the current camera position by registering the currently captured point cloud to the previous one.However,its performance sufers from data association problem or it requires pre-alignment information.The performance of the proposed principal direction detection approach does not rely on data association knowledge.Using this method,two point clouds are properly pre-aligned.Hence,we can use ICP to fne-tune the transformation parameters and minimize registration error.Experimental results demonstrate the performance and stability of the proposed system under disturbance in real-time.Several indoor tests are carried out to show that the proposed visual odometry estimation method can help to signifcantly improve the accuracy of simultaneous localization and mapping（SLAM）.展开更多
基金support by the National Science and Technology Council under Grant No.NSTC 112-2221-E-167-017-MY3.
文摘Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments.Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energysaving potential under varying conditions.Results show that increasing the AC setpoint from 25○C to 27○C,combined with ceiling fan operation,reduced power consumption by 10%,achieving significant energy savings.Survey data confirmed that 85%of participants reported consistent thermal sensations across all conditions,with ceiling fans effectively compensating for higher setpoints through enhanced air circulation.CFDsimulations revealed that mediumspeed ceiling fan operation produced the most uniformairflowdistribution,with an average air velocity of 0.45 m/s,and minimized temperature variations,ensuring balanced thermal conditions.Temperature analysis showed a reduction in hotspots and cold zones,maintaining an average temperature deviation of less than±0.5○C.Predicted Mean Vote(PMV)evaluations at a 27○C setpoint indicated improved thermal comfort,with average PMV values around−0.3,corresponding to a“neutral”thermal sensation.These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort,offering a sustainable approach to reducing AC energy consumption in office environments.
基金Research fund for earthquake engineering of China Earthquake Administration(201508023)a project of the National Science&Technology Support Program during the Twelfth Five-year Plan Period of China(2015BAK17B03)a general program of National Natural Science Foundation of China(51578515)
文摘Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.
基金supported by the National Natural Science Foundation of China(No.11902017)the China Postdoctoral Science Foundation(Nos.2020T130043,2019M650418).
文摘Numerous investigations have been conducted to understand the wall effects on rotors.The purpose of this study is to further investigate the aerodynamic performance of revolving wings,especially when it is very close to the ground and ceiling(i.e.,less than half the wingspan)at low Reynolds numbers.Hence,the ground and ceiling effect for hovering micro revolving wings at low Reynolds numbers are investigated by improving the theoretical models.The theoretical model for the ground effect is established based on the wall-jet assumption,and that for the ceiling effect is improved by considering the uneven spanwise distribution of induced velocity.These two models are validated by comparing the results of experiments and CFD simulations with the Lattice-Boltzmann Method(LBM).Both ground and ceiling effects are found helpful to enhance the thrust,especially with small wing-wall distances,by making a difference to the induced velocity and the pressure distribution.By comparing the thrust generation and aerodynamic efficiency between the ground and ceiling effects,the former is found more helpful to the thrust augmentation,and the latter is more beneficial for the aerodynamic efficiency promotion.
文摘In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error accumulation problem in most visual odometry estimation approaches.The principal direction is defned based on the fact that our ceiling is flled with artifcial vertical and horizontal lines which can be used as reference for the current robot s heading direction.The proposed approach can be operated in real-time and it performs well even with camera s disturbance.A moving low-cost RGB-D camera（Kinect）,mounted on a robot,is used to continuously acquire point clouds.Iterative closest point（ICP） is the common way to estimate the current camera position by registering the currently captured point cloud to the previous one.However,its performance sufers from data association problem or it requires pre-alignment information.The performance of the proposed principal direction detection approach does not rely on data association knowledge.Using this method,two point clouds are properly pre-aligned.Hence,we can use ICP to fne-tune the transformation parameters and minimize registration error.Experimental results demonstrate the performance and stability of the proposed system under disturbance in real-time.Several indoor tests are carried out to show that the proposed visual odometry estimation method can help to signifcantly improve the accuracy of simultaneous localization and mapping（SLAM）.
