This paper analyzes the applications of four air terminal device（ATD）models（i.e.,the basic model,the box model,the N-point momentum model,the jet main region specification model）in computational fluid dynamics（CF...This paper analyzes the applications of four air terminal device（ATD）models（i.e.,the basic model,the box model,the N-point momentum model,the jet main region specification model）in computational fluid dynamics（CFD）simulation and their performance in case study.A full-scale experiment is performed in an environment chamber,and the measured air velocity and temperature fields are compared with the simulation results by using four ATD models.The velocity and temperature fields are measured by an omni-directional thermo-anemometer system.It demonstrates that the basic model and the box model are not applicable to complicated air terminal devices.At the occupant area,the relative errors between simulated and measured air velocities are less than 20% based on the N-point momentum model and the jet main region specification model.Around the ATD zone,the relative error between the numerical and measured air velocity based on the jet main region specification model is less than 15%.The jet main region specification model is proved to be an applicable approach and a more accurate way to study the airflow pattern around the ATD with complicated geometry.展开更多
Background： Physical activity （PA） includes muscle activity during exercise, manual work, and leisure time activities including sport. Conflicting results exist regarding health effects of PA that may deteriorate w...Background： Physical activity （PA） includes muscle activity during exercise, manual work, and leisure time activities including sport. Conflicting results exist regarding health effects of PA that may deteriorate with manual work and elite sports, but improve when performed in moderation in accordance with international guidelines and may additionally enhance well-being and productivity. Methods： In Denmark 15 randomized controlled trials have been conducted, introducing exercise at the workplace enrolling 〉3500 workers. The interventions lasted from 10 to 52 weeks and offered -1 h weekly supervised exercise during working hours according to the concept of intelligent physical exercise training （IPET） that is based on evidenced sports sciences training principles and tailored to work exposure, employee health status, and physical capacity. Questionnaire surveys and health checks including blood and muscle sampling were performed at baseline and follow-up. The job groups included： office and computer workers, dentists, industrial technicians, cleaning personnel, health care workers, construction workers, and fighter/helicopter pilots. Results： In all job groups significant improvements were documented regarding health outcomes. These were job group specific： neck pain was reduced among office and computer workers, dentists, industrial laboratory technicians, health care workers as well as fighter pilots. Cardio- respiratory fitness--a health risk indicator for cardio-metabolic diseases--was improved among office and computer workers, health care workers, and construction workers. Additionally, other improvements were evidenced such as increased muscle strength and balance control. Importantly, productivity increased with improved muscle strength and decreased body mass index. Conclusion： IPET does enhance health if an exercise program with evidenced efficacy is implemented by expert trainees with support of the employer. Accordingly, in every study group outcomes of improved health were documented and the effect sizes were of clinical relevance. Cost effectiveness estimates indicate acceptable cost relative to savings on health expenses and lost productivity.展开更多
Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,...Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,liquid-gas ratio,inlet gas flow rate,inlet concentration of SO2 in flue gas,sodium citrate buffer concentration and initial pH of absorption solution,on the SO2 concentration in the absorption solution or removal efficiency of SO2 were examined.Incremental rate of sulfate radical ions in the absorption solution was also examined.Experimental results indicate that the efficiency of this regenerative process will be improved by using RPB under appropriate operating conditions,and the generation of SO2-4 will be restrained in the process in RPB.展开更多
A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited rin...A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited ring modified from a traditional split-ring resonator(SRR)antenna and an inner SRR load,so the antenna can be regarded as a short-circuited ring loaded with SRR.According to the transmission line theory,to conjugate match with the capacitive input-impedance of a tag chip,the length of the short-circuited ring isλg/4 shorter than that of an open-circuited dipole of a traditional SRR antenna,whereλg is the wavelengh of the operating frequency.Hence,the size of the proposed antenna is more compact than that of the traditional SRR antenna.Thereafter,the proposed antenna is simulated and optimized by ANSYS high-frequency structure simulator(HFSS).The impedance,efficiency,and mutual coupling of the fabricated antenna are tested in a reverberation chamber(RC).The results show that the size of the presented antenna is 83%smaller than that of the traditional SRR antenna and the proposed antenna can cover the whole UHF RFID operating frequency band worldwide(840—960 MHz).The measured read range of the tag exhibits maximum values of 45 cm in free space and 37 cm under dense tag environment.展开更多
文摘This paper analyzes the applications of four air terminal device（ATD）models（i.e.,the basic model,the box model,the N-point momentum model,the jet main region specification model）in computational fluid dynamics（CFD）simulation and their performance in case study.A full-scale experiment is performed in an environment chamber,and the measured air velocity and temperature fields are compared with the simulation results by using four ATD models.The velocity and temperature fields are measured by an omni-directional thermo-anemometer system.It demonstrates that the basic model and the box model are not applicable to complicated air terminal devices.At the occupant area,the relative errors between simulated and measured air velocities are less than 20% based on the N-point momentum model and the jet main region specification model.Around the ATD zone,the relative error between the numerical and measured air velocity based on the jet main region specification model is less than 15%.The jet main region specification model is proved to be an applicable approach and a more accurate way to study the airflow pattern around the ATD with complicated geometry.
文摘Background： Physical activity （PA） includes muscle activity during exercise, manual work, and leisure time activities including sport. Conflicting results exist regarding health effects of PA that may deteriorate with manual work and elite sports, but improve when performed in moderation in accordance with international guidelines and may additionally enhance well-being and productivity. Methods： In Denmark 15 randomized controlled trials have been conducted, introducing exercise at the workplace enrolling 〉3500 workers. The interventions lasted from 10 to 52 weeks and offered -1 h weekly supervised exercise during working hours according to the concept of intelligent physical exercise training （IPET） that is based on evidenced sports sciences training principles and tailored to work exposure, employee health status, and physical capacity. Questionnaire surveys and health checks including blood and muscle sampling were performed at baseline and follow-up. The job groups included： office and computer workers, dentists, industrial technicians, cleaning personnel, health care workers, construction workers, and fighter/helicopter pilots. Results： In all job groups significant improvements were documented regarding health outcomes. These were job group specific： neck pain was reduced among office and computer workers, dentists, industrial laboratory technicians, health care workers as well as fighter pilots. Cardio- respiratory fitness--a health risk indicator for cardio-metabolic diseases--was improved among office and computer workers, health care workers, and construction workers. Additionally, other improvements were evidenced such as increased muscle strength and balance control. Importantly, productivity increased with improved muscle strength and decreased body mass index. Conclusion： IPET does enhance health if an exercise program with evidenced efficacy is implemented by expert trainees with support of the employer. Accordingly, in every study group outcomes of improved health were documented and the effect sizes were of clinical relevance. Cost effectiveness estimates indicate acceptable cost relative to savings on health expenses and lost productivity.
基金Supported by the National Natural Science Foundation of China （20572128）
文摘Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,liquid-gas ratio,inlet gas flow rate,inlet concentration of SO2 in flue gas,sodium citrate buffer concentration and initial pH of absorption solution,on the SO2 concentration in the absorption solution or removal efficiency of SO2 were examined.Incremental rate of sulfate radical ions in the absorption solution was also examined.Experimental results indicate that the efficiency of this regenerative process will be improved by using RPB under appropriate operating conditions,and the generation of SO2-4 will be restrained in the process in RPB.
文摘A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited ring modified from a traditional split-ring resonator(SRR)antenna and an inner SRR load,so the antenna can be regarded as a short-circuited ring loaded with SRR.According to the transmission line theory,to conjugate match with the capacitive input-impedance of a tag chip,the length of the short-circuited ring isλg/4 shorter than that of an open-circuited dipole of a traditional SRR antenna,whereλg is the wavelengh of the operating frequency.Hence,the size of the proposed antenna is more compact than that of the traditional SRR antenna.Thereafter,the proposed antenna is simulated and optimized by ANSYS high-frequency structure simulator(HFSS).The impedance,efficiency,and mutual coupling of the fabricated antenna are tested in a reverberation chamber(RC).The results show that the size of the presented antenna is 83%smaller than that of the traditional SRR antenna and the proposed antenna can cover the whole UHF RFID operating frequency band worldwide(840—960 MHz).The measured read range of the tag exhibits maximum values of 45 cm in free space and 37 cm under dense tag environment.
