STEM是科学(Sci ence)、技术(Technol ogy)、工程(Engi neer i ng)和数学(Mat hemat i cs)的简称,STEM教育强调多学科的交叉融合。为了解决学校教育中的STEM教育在时间、资源上的局限性,科学教育界积极探索在非正式教育环境开展STEM教...STEM是科学(Sci ence)、技术(Technol ogy)、工程(Engi neer i ng)和数学(Mat hemat i cs)的简称,STEM教育强调多学科的交叉融合。为了解决学校教育中的STEM教育在时间、资源上的局限性,科学教育界积极探索在非正式教育环境开展STEM教育的可行性。本文以美国拉斐特学院创办的STEM活动营项目为例,对其目标、课程设置、组织形式和评价策略进行分析,以期对我国STEM教育在非正式教育中的拓展有所启发。展开更多
Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system.Following surgery,the poor regenerative capacity of nerve cells and t...Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system.Following surgery,the poor regenerative capacity of nerve cells and the generation of new scars can make it very difficult for the impaired nervous system to restore its neural functionality.Traditional treatments can only alleviate secondary injuries but cannot fundamentally repair the spinal cord.Consequently,there is a critical need to develop new treatments to promote functional repair after spinal cord injury.Over recent years,there have been seve ral developments in the use of stem cell therapy for the treatment of spinal cord injury.Alongside significant developments in the field of tissue engineering,three-dimensional bioprinting technology has become a hot research topic due to its ability to accurately print complex structures.This led to the loading of three-dimensional bioprinting scaffolds which provided precise cell localization.These three-dimensional bioprinting scaffolds co uld repair damaged neural circuits and had the potential to repair the damaged spinal cord.In this review,we discuss the mechanisms underlying simple stem cell therapy,the application of different types of stem cells for the treatment of spinal cord injury,and the different manufa cturing methods for three-dimensional bioprinting scaffolds.In particular,we focus on the development of three-dimensional bioprinting scaffolds for the treatment of spinal cord injury.展开更多
The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy anal...The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy analysis of any condensate heating system should be avoided because it is highly influenced by the measuring equipment accuracy and precision.All the components from the observed marine condensate heating system have energy destructions lower than 3 kW,while the energy efficiencies of this system are higher than 99%.The exergy efficiency of closed condensate heaters continuously increases from the lowest to the highest steam pressures(from 70.10%to 92.29%).The ambient temperature variation between 5℃and 45℃notably influences the exergy efficiency change of both low pressure heaters and the low pressure segment equal to 31.61%,12.37%,and 18.35%,respectively.展开更多
随着STEM教育向STEAM教育的转变,艺术如何与STEM课程融合有待系统研究。文章基于《美国新泽西州艺术融合指南》(Arts Integration User Guide for New Jersey Educators and Practitioners),构建了艺术与STEM课程融合的方法:"用艺...随着STEM教育向STEAM教育的转变,艺术如何与STEM课程融合有待系统研究。文章基于《美国新泽西州艺术融合指南》(Arts Integration User Guide for New Jersey Educators and Practitioners),构建了艺术与STEM课程融合的方法:"用艺术方式增强STEM课程"及"用STEM方式增强艺术课程";从"社会—学校—教师"三个层面形成艺术与STEM课程融合路径:"社会支持"确保领导的批准和支持;"学校规划"建立艺术与STEM课程融合团队,制定艺术与STEM课程融合愿景和行动计划;"教师行动"开发艺术与STEM融合课程,提供以工作为基础的专业学习和辅导,建立文档、记录数据和评估,确保可持续发展。面向STEAM教育,艺术与STEM课程融合带来的启示为:实施"社会—学校—教师"协同的艺术与STEM课程融合路径;突出艺术与STEM课程融合的问题意识,创新应用的融合方法;构建艺术与STEM课程融合的专业团队,形成充分的人力资源支持;平衡艺术与STEM课程标准,开发符合学情的课程资源;记录艺术与STEM课程融合的过程数据,开展融合效果的过程性评价。展开更多
This paper analyzes the main problems of Sinopec Beijing Yanshan Petrochemical Co.,Ltd.,such as decentralized steam system layout,many types of fuels,obvious increase in fuel cost,low operation efficiency of turbine a...This paper analyzes the main problems of Sinopec Beijing Yanshan Petrochemical Co.,Ltd.,such as decentralized steam system layout,many types of fuels,obvious increase in fuel cost,low operation efficiency of turbine and boiler and high self consumption loss,and puts forward and implements optimization and improvement measures such as pressure raising transformation of natural gas system,adjustment of energy consumption structure,reduction of energy consumption cost,improvement of steam production quality and equipment efficiency.The results showed that compared with the fuel consumption in 2018,the consumption of coal coke was reduced by 550000 t,the consumption of natural gas was increased by 170000 t,and the total consumption of fuel gas and fuel oil was increased by 50000 t,equivalent to 246000 t of standard coal;the purchased electricity was increased by about 5×10^(8) kW·h.Green power trading and 14.76 MW distributed photovoltaic projects were carried out.According to the calculation of 1400-1600 h annual power generation in class II photovoltaic areas and the emission factor of North China regional power grid baseline,the annual emission reduction was about 55000 t CO_(2) in 2021.After the above transformation,the goal of zero-coking is achieved;the steam consumption of units is reduced by 21.5%,the steam production of boilers is reduced by 24.9%,and the annual emission reduction is about 760000 t CO_(2),which has achieved good results.展开更多
Mesenchymalstemcells(MSCs)areidealcandidatesfortreatingmanycardiovasculardiseases.MSCscanmodify the internal cardiac microenvironment to facilitate their immunomodulatory and differentiation abilities,which are essent...Mesenchymalstemcells(MSCs)areidealcandidatesfortreatingmanycardiovasculardiseases.MSCscanmodify the internal cardiac microenvironment to facilitate their immunomodulatory and differentiation abilities,which are essential to restore heart function.MSCs can be easily isolated from different sources,including bone marrow,adipose tissues,umbilical cord,and dental pulp.MSCs from various sources differ in their regenerative and therapeutic abilities for cardiovascular disorders.In this review,we will summarize the therapeutic potential of each MSC source for heart diseases and highlight the possible molecular mechanisms of each source to restore cardiac function.展开更多
Through the study on the output signals of the electro-hydraulic regulating system in the thermal power plant, a novel method for online diagnosis of the plugging fault in the servo valve is presented. With the use of...Through the study on the output signals of the electro-hydraulic regulating system in the thermal power plant, a novel method for online diagnosis of the plugging fault in the servo valve is presented. With the use of the AMESIM software, the changes of the piston displacement, the oil pressure, the magnitude attenuation and the phase lag of the system under different plugging states are studied after simulation. Besides, the influences of the symmetrical and unsymmetrical plugging on the system are also compared and the characteristic table is given. The duo-neural network is put forward to achieve an online diagnosis on the plugging fault of the servo valve. The first level of network helps to make the qualitative diagnosis of the plugging position while the second level is for the quantitative diagnosis of the degree of the plugged position. The research results show that plugging at different positions exerts different influences on the performance of the system. The unsymmetrical plugging mainly affects the regulation time while the symmetrical plugging leads to great changes in the magnitude attenuation and the phase lag.展开更多
With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathema...With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathematical model of system is built up. With the use of AMESIM software, the displacement curve of the piston, the force curve of the cartridge valve spool, the pressure curve and the flux curve in the regulation process are obtained based on simulation. The performances of three fast-opening systems composed of cartridge valves with different diameters are compared. Based on the analysis on factors that affect the execution time of fast-opening, the dead zone of the fast-opening system is put forward. To overcome the defect, dif- ferent operation modes are adopted for different zones. The result shows that with the increase of the valve diameter, the regulating time in the dead zone significantly exceeds the fast-opening time in the whole journey. Accordingly, the optimization operation tactic in the dead zone and the qualification conditions are brought forward. The fast-opening system composed of 32 mm cartridge valves is taken as an example with use of the tactic. The simulation result shows that the maximum regulating time is shortened by 509 ms.展开更多
Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are desi...Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are designed using backstepping method. The controller not only considers transmission line parameter uncer-tainty, and has attenuated the influences of large external disturbances on system output. The nonlinear con-troller does not have the sensitivity to the influences of external disturbances, but also has strong robustness for system parameters variation, which is because of the transmission line uncertainty being considered in internal disturbances. The simulation results show that the control effect of the large disturbance attenuation controller more advantages by comparing with the control performance of conventional nonlinear robust controller.展开更多
文摘STEM是科学(Sci ence)、技术(Technol ogy)、工程(Engi neer i ng)和数学(Mat hemat i cs)的简称,STEM教育强调多学科的交叉融合。为了解决学校教育中的STEM教育在时间、资源上的局限性,科学教育界积极探索在非正式教育环境开展STEM教育的可行性。本文以美国拉斐特学院创办的STEM活动营项目为例,对其目标、课程设置、组织形式和评价策略进行分析,以期对我国STEM教育在非正式教育中的拓展有所启发。
基金supported by the National Natural Science Foundation of China,No.82171380(to CD)Jiangsu Students’Platform for Innovation and Entrepreneurship Training Program,No.202110304098Y(to DJ)。
文摘Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system.Following surgery,the poor regenerative capacity of nerve cells and the generation of new scars can make it very difficult for the impaired nervous system to restore its neural functionality.Traditional treatments can only alleviate secondary injuries but cannot fundamentally repair the spinal cord.Consequently,there is a critical need to develop new treatments to promote functional repair after spinal cord injury.Over recent years,there have been seve ral developments in the use of stem cell therapy for the treatment of spinal cord injury.Alongside significant developments in the field of tissue engineering,three-dimensional bioprinting technology has become a hot research topic due to its ability to accurately print complex structures.This led to the loading of three-dimensional bioprinting scaffolds which provided precise cell localization.These three-dimensional bioprinting scaffolds co uld repair damaged neural circuits and had the potential to repair the damaged spinal cord.In this review,we discuss the mechanisms underlying simple stem cell therapy,the application of different types of stem cells for the treatment of spinal cord injury,and the different manufa cturing methods for three-dimensional bioprinting scaffolds.In particular,we focus on the development of three-dimensional bioprinting scaffolds for the treatment of spinal cord injury.
基金This research is supported by the Croatian Science Foundation under the project IP-2018-01-3739,CEEPUS network CIII-HR-0108,European Regional Development Fund under the grant KK.01.1.1.01.0009(DATACROSS)project CEKOM under the grant KK.01.2.2.03.0004,CEI project“COVIDAi”(305.6019-20)University of Rijeka Scientific Grants uniri-tehnic-18-275-1447,uniritehnic-18-18-1146 and uniri-tehnic-18-14.
文摘The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy analysis of any condensate heating system should be avoided because it is highly influenced by the measuring equipment accuracy and precision.All the components from the observed marine condensate heating system have energy destructions lower than 3 kW,while the energy efficiencies of this system are higher than 99%.The exergy efficiency of closed condensate heaters continuously increases from the lowest to the highest steam pressures(from 70.10%to 92.29%).The ambient temperature variation between 5℃and 45℃notably influences the exergy efficiency change of both low pressure heaters and the low pressure segment equal to 31.61%,12.37%,and 18.35%,respectively.
文摘随着STEM教育向STEAM教育的转变,艺术如何与STEM课程融合有待系统研究。文章基于《美国新泽西州艺术融合指南》(Arts Integration User Guide for New Jersey Educators and Practitioners),构建了艺术与STEM课程融合的方法:"用艺术方式增强STEM课程"及"用STEM方式增强艺术课程";从"社会—学校—教师"三个层面形成艺术与STEM课程融合路径:"社会支持"确保领导的批准和支持;"学校规划"建立艺术与STEM课程融合团队,制定艺术与STEM课程融合愿景和行动计划;"教师行动"开发艺术与STEM融合课程,提供以工作为基础的专业学习和辅导,建立文档、记录数据和评估,确保可持续发展。面向STEAM教育,艺术与STEM课程融合带来的启示为:实施"社会—学校—教师"协同的艺术与STEM课程融合路径;突出艺术与STEM课程融合的问题意识,创新应用的融合方法;构建艺术与STEM课程融合的专业团队,形成充分的人力资源支持;平衡艺术与STEM课程标准,开发符合学情的课程资源;记录艺术与STEM课程融合的过程数据,开展融合效果的过程性评价。
文摘This paper analyzes the main problems of Sinopec Beijing Yanshan Petrochemical Co.,Ltd.,such as decentralized steam system layout,many types of fuels,obvious increase in fuel cost,low operation efficiency of turbine and boiler and high self consumption loss,and puts forward and implements optimization and improvement measures such as pressure raising transformation of natural gas system,adjustment of energy consumption structure,reduction of energy consumption cost,improvement of steam production quality and equipment efficiency.The results showed that compared with the fuel consumption in 2018,the consumption of coal coke was reduced by 550000 t,the consumption of natural gas was increased by 170000 t,and the total consumption of fuel gas and fuel oil was increased by 50000 t,equivalent to 246000 t of standard coal;the purchased electricity was increased by about 5×10^(8) kW·h.Green power trading and 14.76 MW distributed photovoltaic projects were carried out.According to the calculation of 1400-1600 h annual power generation in class II photovoltaic areas and the emission factor of North China regional power grid baseline,the annual emission reduction was about 55000 t CO_(2) in 2021.After the above transformation,the goal of zero-coking is achieved;the steam consumption of units is reduced by 21.5%,the steam production of boilers is reduced by 24.9%,and the annual emission reduction is about 760000 t CO_(2),which has achieved good results.
文摘Mesenchymalstemcells(MSCs)areidealcandidatesfortreatingmanycardiovasculardiseases.MSCscanmodify the internal cardiac microenvironment to facilitate their immunomodulatory and differentiation abilities,which are essential to restore heart function.MSCs can be easily isolated from different sources,including bone marrow,adipose tissues,umbilical cord,and dental pulp.MSCs from various sources differ in their regenerative and therapeutic abilities for cardiovascular disorders.In this review,we will summarize the therapeutic potential of each MSC source for heart diseases and highlight the possible molecular mechanisms of each source to restore cardiac function.
基金supported by National Natural Science Foundation of China (Grant No. 50575202)
文摘Through the study on the output signals of the electro-hydraulic regulating system in the thermal power plant, a novel method for online diagnosis of the plugging fault in the servo valve is presented. With the use of the AMESIM software, the changes of the piston displacement, the oil pressure, the magnitude attenuation and the phase lag of the system under different plugging states are studied after simulation. Besides, the influences of the symmetrical and unsymmetrical plugging on the system are also compared and the characteristic table is given. The duo-neural network is put forward to achieve an online diagnosis on the plugging fault of the servo valve. The first level of network helps to make the qualitative diagnosis of the plugging position while the second level is for the quantitative diagnosis of the degree of the plugged position. The research results show that plugging at different positions exerts different influences on the performance of the system. The unsymmetrical plugging mainly affects the regulation time while the symmetrical plugging leads to great changes in the magnitude attenuation and the phase lag.
基金Project (No. NCET-04-0545) supported by the "New Century Elitist Supporting Plan" Fund Project of Education Ministry of China
文摘With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathematical model of system is built up. With the use of AMESIM software, the displacement curve of the piston, the force curve of the cartridge valve spool, the pressure curve and the flux curve in the regulation process are obtained based on simulation. The performances of three fast-opening systems composed of cartridge valves with different diameters are compared. Based on the analysis on factors that affect the execution time of fast-opening, the dead zone of the fast-opening system is put forward. To overcome the defect, dif- ferent operation modes are adopted for different zones. The result shows that with the increase of the valve diameter, the regulating time in the dead zone significantly exceeds the fast-opening time in the whole journey. Accordingly, the optimization operation tactic in the dead zone and the qualification conditions are brought forward. The fast-opening system composed of 32 mm cartridge valves is taken as an example with use of the tactic. The simulation result shows that the maximum regulating time is shortened by 509 ms.
文摘Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are designed using backstepping method. The controller not only considers transmission line parameter uncer-tainty, and has attenuated the influences of large external disturbances on system output. The nonlinear con-troller does not have the sensitivity to the influences of external disturbances, but also has strong robustness for system parameters variation, which is because of the transmission line uncertainty being considered in internal disturbances. The simulation results show that the control effect of the large disturbance attenuation controller more advantages by comparing with the control performance of conventional nonlinear robust controller.
