To simulate the process of electrode operation, a dynamic model describing the electrode system of three-phase electric arc furnace was developed. This new model can be divided into three submodels in terms of the pra...To simulate the process of electrode operation, a dynamic model describing the electrode system of three-phase electric arc furnace was developed. This new model can be divided into three submodels in terms of the practical situation. They are the power supply system model the electric arc model and the hydraulic actuator system model. According to the basic circuit theory, the power supply system model where the high voltage transmission circuit and mutual inductances were considered, was set up. The electric arc model, which was novel for the electrode control, served as the electrical load and was connected to the power supply system model. The hydraulic actuator system model consists of the proportional valve part that is modeled to capture the dead-zone nonlinear characteristics and the hydraulic cylinder part where the impact of the load force is taken into account. By comparing simulation data and actual data, the results show that the electrode system model is proved to be accurate.展开更多
An arc model considering deviations from thermodynamic and chemical equilibrium has been developed in order to achieve a better understanding of the arc plasma close to material surfaces.The model is based on unified ...An arc model considering deviations from thermodynamic and chemical equilibrium has been developed in order to achieve a better understanding of the arc plasma close to material surfaces.The model is based on unified consideration of the thermionic tungsten cathode,the arc region and the flat anode made of copper.The heat transfer within the electrodes is coupled with the plasma through the energy fluxes onto the electrode boundaries.Electrical characteristics of an 8 mm long free-burning arc are presented along with findings from spectroscopic measurements of the plasma emission in atmospheric pressure argon.The arc current varied from 60 A up to 200 A,and the gas flow rate was set at 12 L/min(at atmospheric pressure,room temperature).展开更多
该文以ARCS模型为理论分析框架,探析高校针对MOOC(Massive Open Online Course:大规模开放性在线课程)的有效应用——无论是基于MOOC的引入还是基于MOOC的建设,如何将MOOC从一个炙手可热且容易被夸大、被炒作的概念落实为切实推进高校...该文以ARCS模型为理论分析框架,探析高校针对MOOC(Massive Open Online Course:大规模开放性在线课程)的有效应用——无论是基于MOOC的引入还是基于MOOC的建设,如何将MOOC从一个炙手可热且容易被夸大、被炒作的概念落实为切实推进高校教育教学改革、教育教学质量提升的创新实践。ARCS模型界定了人类动机四个相互关联的构成要素,包括关注(Attention)、关联(Relevance)、自信(Confidence)与满意(Satisfaction),强调如何通过外部的设计激发与维持内部动机的生成。分析结果表明,在ARCS模型视角下,一方面,高校需要积极关注MOOC的应用价值与意义,具有主动适应信息社会发展应用MOOC的主动意识;另一方面,高校需要根据学校的实际发展基础与需求,对MOOC的有效应用进行主动地设计与实践,激发与维持本校深入应用MOOC的动机。高校推进MOOC有效应用的路径具体体现为:在意识层面对MOOC本质与应用意义的自觉关注;在规划层面与学校长远发展目标与核心发展目标的高度关联;在实践层面具备应对MOOC挑战的充分自信;在效果层面注重评价与研究提升效果满意度促进MOOC的可持续应用与发展。展开更多
基金Projects(2007AA04Z194, 2007AA041401) supported by the National High-Tech Research and Development Program of China
文摘To simulate the process of electrode operation, a dynamic model describing the electrode system of three-phase electric arc furnace was developed. This new model can be divided into three submodels in terms of the practical situation. They are the power supply system model the electric arc model and the hydraulic actuator system model. According to the basic circuit theory, the power supply system model where the high voltage transmission circuit and mutual inductances were considered, was set up. The electric arc model, which was novel for the electrode control, served as the electrical load and was connected to the power supply system model. The hydraulic actuator system model consists of the proportional valve part that is modeled to capture the dead-zone nonlinear characteristics and the hydraulic cylinder part where the impact of the load force is taken into account. By comparing simulation data and actual data, the results show that the electrode system model is proved to be accurate.
文摘An arc model considering deviations from thermodynamic and chemical equilibrium has been developed in order to achieve a better understanding of the arc plasma close to material surfaces.The model is based on unified consideration of the thermionic tungsten cathode,the arc region and the flat anode made of copper.The heat transfer within the electrodes is coupled with the plasma through the energy fluxes onto the electrode boundaries.Electrical characteristics of an 8 mm long free-burning arc are presented along with findings from spectroscopic measurements of the plasma emission in atmospheric pressure argon.The arc current varied from 60 A up to 200 A,and the gas flow rate was set at 12 L/min(at atmospheric pressure,room temperature).
文摘该文以ARCS模型为理论分析框架,探析高校针对MOOC(Massive Open Online Course:大规模开放性在线课程)的有效应用——无论是基于MOOC的引入还是基于MOOC的建设,如何将MOOC从一个炙手可热且容易被夸大、被炒作的概念落实为切实推进高校教育教学改革、教育教学质量提升的创新实践。ARCS模型界定了人类动机四个相互关联的构成要素,包括关注(Attention)、关联(Relevance)、自信(Confidence)与满意(Satisfaction),强调如何通过外部的设计激发与维持内部动机的生成。分析结果表明,在ARCS模型视角下,一方面,高校需要积极关注MOOC的应用价值与意义,具有主动适应信息社会发展应用MOOC的主动意识;另一方面,高校需要根据学校的实际发展基础与需求,对MOOC的有效应用进行主动地设计与实践,激发与维持本校深入应用MOOC的动机。高校推进MOOC有效应用的路径具体体现为:在意识层面对MOOC本质与应用意义的自觉关注;在规划层面与学校长远发展目标与核心发展目标的高度关联;在实践层面具备应对MOOC挑战的充分自信;在效果层面注重评价与研究提升效果满意度促进MOOC的可持续应用与发展。
