This essay mainly focuses on the feedback move in IRF(initiate- response- feedback) to investigate the characters and functions of teacher feedback in different class types through classroom observation. The research ...This essay mainly focuses on the feedback move in IRF(initiate- response- feedback) to investigate the characters and functions of teacher feedback in different class types through classroom observation. The research finds that(1) teachers in different class types prefer to adopt evaluative feedback and use more positive feedback.(2) the proportion of each feedback is different in listening and speaking, reading and writing class. The implications are that English teachers in senior high school should adopt different feedback flexibly and consider what kind of feedback is more likely elicit the students' output in different class types.展开更多
Corrective feedback is an important part of second language acquisition, and many researches have showed that the corrective feedback in general have a positive effect on second language acquisition. The present study...Corrective feedback is an important part of second language acquisition, and many researches have showed that the corrective feedback in general have a positive effect on second language acquisition. The present study aims to investigate corrective feedback and draw enlightening conclusions:1) Different corrective feedback types have different effects on second language acquisition; 2)The effect of corrective feedback is also influenced by the feedback timing, explicitness of the feedback and learners' individual differences; 3) Teachers should consider feedback types, feedback timing, and individual differences of students based on teaching contents when providing corrective feedback in foreign language teaching.展开更多
三相电流源型PWM整流器(Current Source Rectifier,CSR)因其可实现网侧单位因数和正弦波电流控制,具备电能双向传输能力,广泛应用于应急电源系统(Emergency Power Supply,EPS)的电能转换系统。针对CSR的LC滤波电路容易产生谐振,以及带...三相电流源型PWM整流器(Current Source Rectifier,CSR)因其可实现网侧单位因数和正弦波电流控制,具备电能双向传输能力,广泛应用于应急电源系统(Emergency Power Supply,EPS)的电能转换系统。针对CSR的LC滤波电路容易产生谐振,以及带容性负载输出时,数学模型阶数增加导致控制器参数设计复杂等问题,提出了一种组合型有源阻尼解耦控制策略。首先,在d-q坐标下建立带容性负载的CSR数学模型;其次,CSR交流侧采用电容电压反馈(Capacitance Voltage Feedback,CVF)和电感电流反馈(Inductance Current Feedback,ICF)的组合型有源阻尼控制,以抑制交流侧LC滤波器谐振尖峰并提高系统阻尼比,直流侧采用状态反馈控制以稳定直流母线电压;然后,调节d轴开关分量实现系统网侧电压电流同相位运行;最后,通过MATALB/Simulink仿真及实验,验证了该控制策略的可行性。展开更多
文摘This essay mainly focuses on the feedback move in IRF(initiate- response- feedback) to investigate the characters and functions of teacher feedback in different class types through classroom observation. The research finds that(1) teachers in different class types prefer to adopt evaluative feedback and use more positive feedback.(2) the proportion of each feedback is different in listening and speaking, reading and writing class. The implications are that English teachers in senior high school should adopt different feedback flexibly and consider what kind of feedback is more likely elicit the students' output in different class types.
文摘Corrective feedback is an important part of second language acquisition, and many researches have showed that the corrective feedback in general have a positive effect on second language acquisition. The present study aims to investigate corrective feedback and draw enlightening conclusions:1) Different corrective feedback types have different effects on second language acquisition; 2)The effect of corrective feedback is also influenced by the feedback timing, explicitness of the feedback and learners' individual differences; 3) Teachers should consider feedback types, feedback timing, and individual differences of students based on teaching contents when providing corrective feedback in foreign language teaching.
文摘针对虚拟同步发电机VSG(virtual synchronous generator)自适应控制大范围调节参数导致需要较大储能容量配置的问题,设计ln基底型自适应控制策略以优化储能容量配置。通过对基于速度反馈控制的虚拟同步发电机VF-VSG(velocity feedback control based VSG)进行数学建模,建立VSG在输入功率扰动时与所需储能容量之间的关系,据此分析速度反馈系数、VSG转动惯量和阻尼系数对储能容量的影响,以此设计ln基底型自适应控制策略,避免参数大范围调节,优化储能容量配置。通过仿真实验可知:所提控制策略在暂态性能优良的前提下,降低了9.8%储能容量的配置,验证了所提策略的有效性。
文摘三相电流源型PWM整流器(Current Source Rectifier,CSR)因其可实现网侧单位因数和正弦波电流控制,具备电能双向传输能力,广泛应用于应急电源系统(Emergency Power Supply,EPS)的电能转换系统。针对CSR的LC滤波电路容易产生谐振,以及带容性负载输出时,数学模型阶数增加导致控制器参数设计复杂等问题,提出了一种组合型有源阻尼解耦控制策略。首先,在d-q坐标下建立带容性负载的CSR数学模型;其次,CSR交流侧采用电容电压反馈(Capacitance Voltage Feedback,CVF)和电感电流反馈(Inductance Current Feedback,ICF)的组合型有源阻尼控制,以抑制交流侧LC滤波器谐振尖峰并提高系统阻尼比,直流侧采用状态反馈控制以稳定直流母线电压;然后,调节d轴开关分量实现系统网侧电压电流同相位运行;最后,通过MATALB/Simulink仿真及实验,验证了该控制策略的可行性。
