Nowadays,the number of vehicles in China has increased significantly.The increase of the number of vehicles has also led to the increasingly complex traffic situation and the urgent safety measures in need.However,the...Nowadays,the number of vehicles in China has increased significantly.The increase of the number of vehicles has also led to the increasingly complex traffic situation and the urgent safety measures in need.However,the existing early warning devices such as geomagnetic,ultrasonic and infrared detection have some shortcomings like difficult installation and maintenance.In addition,geomagnetic detection will damage the road surface,while ultrasonic and infrared detection will be greatly affected by the environment.Considering the shortcomings of the existing solutions,this paper puts forward a solution of early warning for vehicle turning meeting based on image acquisition and microcontrollers.This solution combines image acquisition and processing technology,which uses image sensor to perceive traffic condition and image data analysis algorithm to process perceived image,and then utilize LED display screen to issue an early warning.展开更多
The organic Rankine cycle(ORC)is a popular technique used in the utilization of low-grade thermal energy.Among wet,dry,and isentropic organic working fluids,the latter two types are more appropriate for ORC systems.In...The organic Rankine cycle(ORC)is a popular technique used in the utilization of low-grade thermal energy.Among wet,dry,and isentropic organic working fluids,the latter two types are more appropriate for ORC systems.In this paper,the definition of turning point on saturated vapor curve of dry fluid and isentropic fluid was given according to the shape of the saturated curve of working fluids in a T-s diagram.On this basis,the model of near-critical region triangle was established.Using this model,the thermodynamic performance of 57 kinds of dry and isentropic organic working fluids in ORC was evaluated.The performance includes the relation between turning point temperature and cycle thermal efficiency,the relation between near-critical region triangle area and cycle thermal efficiency,the relation between near-critical region triangle area and exergy at turning point temperature,the relation between near-critical region triangle area and reciprocal value of slope of saturated vapor curve.Moreover,working fluid selection was also conducted in terms of heat source type.It was found through theoretical analysis results that the popular R123 is an acceptable choice especially for the utilization of closed type heat source.Considering it will be phased out in near future,then cis-butene,butane,trans-butene,and isobutene are worth studying as its successor.Dodecane is worthy of attention and further research and it can be a good choice for utilization of open type heat source.展开更多
潍烟高速铁路两处单线特大桥跨越既有青荣城际铁路均采用2-100 m T型刚构转体施工,T型刚构分别位于半径R=800 m和R=500 m的曲线上,是铁路百米以上跨度T型刚构所采用的最小曲线半径。针对该转体T型刚构施工设计,对T型刚构的结构概况、转...潍烟高速铁路两处单线特大桥跨越既有青荣城际铁路均采用2-100 m T型刚构转体施工,T型刚构分别位于半径R=800 m和R=500 m的曲线上,是铁路百米以上跨度T型刚构所采用的最小曲线半径。针对该转体T型刚构施工设计,对T型刚构的结构概况、转体系统和转体施工方法进行详细介绍,提出了铁路小曲线半径大跨度T型刚构转体施工的关键技术,对类似工程具有一定的借鉴意义。展开更多
基金This project is supported by the Cooperative Education Fund of China Ministry of Education(201702113002,201801193119)Hunan Natural Science Foundation(2018JJ2138)+2 种基金Excellent Youth Project of Hunan Education Department(17B096)the H3C Fund of Hunan Internet of Things Federation(20180006)Degree and Graduate Education Reform Project of Hunan Province(JG2018B096).
文摘Nowadays,the number of vehicles in China has increased significantly.The increase of the number of vehicles has also led to the increasingly complex traffic situation and the urgent safety measures in need.However,the existing early warning devices such as geomagnetic,ultrasonic and infrared detection have some shortcomings like difficult installation and maintenance.In addition,geomagnetic detection will damage the road surface,while ultrasonic and infrared detection will be greatly affected by the environment.Considering the shortcomings of the existing solutions,this paper puts forward a solution of early warning for vehicle turning meeting based on image acquisition and microcontrollers.This solution combines image acquisition and processing technology,which uses image sensor to perceive traffic condition and image data analysis algorithm to process perceived image,and then utilize LED display screen to issue an early warning.
基金supported by the National Natural Science Foundation of China(Grant No.51506001)Beijing Municipal Education Commission(KM201710005029)National Key R&D Program of China(Grant No.2016YFE0124900)
文摘The organic Rankine cycle(ORC)is a popular technique used in the utilization of low-grade thermal energy.Among wet,dry,and isentropic organic working fluids,the latter two types are more appropriate for ORC systems.In this paper,the definition of turning point on saturated vapor curve of dry fluid and isentropic fluid was given according to the shape of the saturated curve of working fluids in a T-s diagram.On this basis,the model of near-critical region triangle was established.Using this model,the thermodynamic performance of 57 kinds of dry and isentropic organic working fluids in ORC was evaluated.The performance includes the relation between turning point temperature and cycle thermal efficiency,the relation between near-critical region triangle area and cycle thermal efficiency,the relation between near-critical region triangle area and exergy at turning point temperature,the relation between near-critical region triangle area and reciprocal value of slope of saturated vapor curve.Moreover,working fluid selection was also conducted in terms of heat source type.It was found through theoretical analysis results that the popular R123 is an acceptable choice especially for the utilization of closed type heat source.Considering it will be phased out in near future,then cis-butene,butane,trans-butene,and isobutene are worth studying as its successor.Dodecane is worthy of attention and further research and it can be a good choice for utilization of open type heat source.
文摘潍烟高速铁路两处单线特大桥跨越既有青荣城际铁路均采用2-100 m T型刚构转体施工,T型刚构分别位于半径R=800 m和R=500 m的曲线上,是铁路百米以上跨度T型刚构所采用的最小曲线半径。针对该转体T型刚构施工设计,对T型刚构的结构概况、转体系统和转体施工方法进行详细介绍,提出了铁路小曲线半径大跨度T型刚构转体施工的关键技术,对类似工程具有一定的借鉴意义。
