The pollutant control performance of exhaust hoods plays a crucial role in the indoor air quality and energy consumption of ventilation systems in industrial buildings.To better understand the impact of local ventilat...The pollutant control performance of exhaust hoods plays a crucial role in the indoor air quality and energy consumption of ventilation systems in industrial buildings.To better understand the impact of local ventilation on the industrial indoor environment,this paper presents a literature review of exhaust hood performance and its improvement technologies.To create an index for evaluating the performance of exhaust hoods,the capture velocity,capture efficiency,flow ratio of pollutant emissions and exhaust airflow and energy consumption are first introduced.A number of factors affecting exhaust hood performance are assessed such as hood type,hood opening size,exhaust rate,installation distance,pollution source emission and environmental disturbance.Compared to structural improvement methods,the use of active airflow is a more effective way to improve the exhaust hood performance.The most commonly used methods for determining the exhaust rate are the controlled speed method and the flow ratio method.The use of an exhaust hood with an appropriate exhaust rate and jet parameters(for an active air-assisted hood)can effectively improve the pollutant control performance and reduce the energy consumption that would be wasted on the redundant exhaust rate.With more information focused on exhaust hood performance,this work suggests more effective strategies for improving indoor air quality and reducing energy consumption in industrial buildings.展开更多
The effect of laser assisted local heating on the mechanical properties of a hot stamping steel tube was in vestigated. A heated region with a spiral shape was generated on the surface of the tube by combining the lin...The effect of laser assisted local heating on the mechanical properties of a hot stamping steel tube was in vestigated. A heated region with a spiral shape was generated on the surface of the tube by combining the linear movement of the laser and the rotation of the tube. The results of axial crush tests show that the laser assisted local heating can be effectively used to modify the mechanical performance of the tube. A microstructural analysis confirms that the laser locally induces a martensitic phase transformation in the heated region and results in inhomogeneous microstructures alon- the length of the tube.展开更多
Echolocating bats possess remarkable capability of multitarget spatial localization and micromotion sensing in a full field of view(FFOV)even in cluttered environments.Artificial technologies with such capability are ...Echolocating bats possess remarkable capability of multitarget spatial localization and micromotion sensing in a full field of view(FFOV)even in cluttered environments.Artificial technologies with such capability are highly desirable for various fields.However,current techniques such as visual sensing and laser scanning suffer from numerous fundamental problems.Here,we develop a bioinspired concept of millimeter-wave(mmWave)full-field micromotion sensing,creating a unique mmWave Bat(“mmWBat”),which can map and quantify tiny motions spanning macroscopic toμm length scales of full-field targets simultaneously and accurately.In mmWBat,we show that the micromotions can be measured via the interferometric phase evolution tracking from range-angle joint dimension,integrating with full-field localization and tricky clutter elimination.With our approach,we demonstrate the capacity to solve challenges in three disparate applications:multiperson vital sign monitoring,full-field mechanical vibration measurement,and multiple sound source localization and reconstruction(radiofrequency microphone).Our work could potentially revolutionize full-field micromotion monitoring in a wide spectrum of applications,while may inspiring novel biomimetic wireless sensing systems.展开更多
The elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or converge...The elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or convergence problems, thus the evolution of the contact behaviour is obtained in a semi-analytical manner. Numerical results obtained by the proposed approach facilitate the understanding of the contact behaviour in the following aspects: 1) the ratio of contact area to load decreases with an increase in real contact area;2) normal approach-load relationship is approximated by an exponential decay under relatively small loads and a linear decay under relatively large loads;and 3) average gap shows an exponential relationship with load only in moderate load range.展开更多
文摘The pollutant control performance of exhaust hoods plays a crucial role in the indoor air quality and energy consumption of ventilation systems in industrial buildings.To better understand the impact of local ventilation on the industrial indoor environment,this paper presents a literature review of exhaust hood performance and its improvement technologies.To create an index for evaluating the performance of exhaust hoods,the capture velocity,capture efficiency,flow ratio of pollutant emissions and exhaust airflow and energy consumption are first introduced.A number of factors affecting exhaust hood performance are assessed such as hood type,hood opening size,exhaust rate,installation distance,pollution source emission and environmental disturbance.Compared to structural improvement methods,the use of active airflow is a more effective way to improve the exhaust hood performance.The most commonly used methods for determining the exhaust rate are the controlled speed method and the flow ratio method.The use of an exhaust hood with an appropriate exhaust rate and jet parameters(for an active air-assisted hood)can effectively improve the pollutant control performance and reduce the energy consumption that would be wasted on the redundant exhaust rate.With more information focused on exhaust hood performance,this work suggests more effective strategies for improving indoor air quality and reducing energy consumption in industrial buildings.
基金Sponsored by IT R&D Program of MOTIE/KEIT(10044807)National Research Foundation of Korea Grant Funded by the Korean Government(NRF-2013R1A1A2010145)+2 种基金NRF Grant by the Ministry of ScienceICT&Future Planning(MSIP)(NRF-2015R1A5A1037627)Small and Medium Business Support Program(World-class 300Project,S2317960)
文摘The effect of laser assisted local heating on the mechanical properties of a hot stamping steel tube was in vestigated. A heated region with a spiral shape was generated on the surface of the tube by combining the linear movement of the laser and the rotation of the tube. The results of axial crush tests show that the laser assisted local heating can be effectively used to modify the mechanical performance of the tube. A microstructural analysis confirms that the laser locally induces a martensitic phase transformation in the heated region and results in inhomogeneous microstructures alon- the length of the tube.
基金the National Natural Science Foundation of China(Grant No.51905341 and Grant No.11632011)the China Postdoctoral Science Foundation(Grant No.2019M651488)。
文摘Echolocating bats possess remarkable capability of multitarget spatial localization and micromotion sensing in a full field of view(FFOV)even in cluttered environments.Artificial technologies with such capability are highly desirable for various fields.However,current techniques such as visual sensing and laser scanning suffer from numerous fundamental problems.Here,we develop a bioinspired concept of millimeter-wave(mmWave)full-field micromotion sensing,creating a unique mmWave Bat(“mmWBat”),which can map and quantify tiny motions spanning macroscopic toμm length scales of full-field targets simultaneously and accurately.In mmWBat,we show that the micromotions can be measured via the interferometric phase evolution tracking from range-angle joint dimension,integrating with full-field localization and tricky clutter elimination.With our approach,we demonstrate the capacity to solve challenges in three disparate applications:multiperson vital sign monitoring,full-field mechanical vibration measurement,and multiple sound source localization and reconstruction(radiofrequency microphone).Our work could potentially revolutionize full-field micromotion monitoring in a wide spectrum of applications,while may inspiring novel biomimetic wireless sensing systems.
基金The authors acknowledge the financial supports by the National Key Research and Development Program of China(2016YFF0204305)the National Natural Science Foundation of China(51775460 and 51905456)the China Postdoctoral Science Foundation(2019M653836XB).
文摘The elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or convergence problems, thus the evolution of the contact behaviour is obtained in a semi-analytical manner. Numerical results obtained by the proposed approach facilitate the understanding of the contact behaviour in the following aspects: 1) the ratio of contact area to load decreases with an increase in real contact area;2) normal approach-load relationship is approximated by an exponential decay under relatively small loads and a linear decay under relatively large loads;and 3) average gap shows an exponential relationship with load only in moderate load range.
