针对无线通信应用的射频功率放大器,提出了一种新颖的温度补偿电路。应用该温度补偿电路,设计了一款基于In Ga P/Ga As HBT工艺的两级F类功率放大器。该功率放大器采用了带温度补偿特性的有源偏置电路,能有效地提高线性度,补偿温度引起...针对无线通信应用的射频功率放大器,提出了一种新颖的温度补偿电路。应用该温度补偿电路,设计了一款基于In Ga P/Ga As HBT工艺的两级F类功率放大器。该功率放大器采用了带温度补偿特性的有源偏置电路,能有效地提高线性度,补偿温度引起的性能偏差;输出匹配网络采用F类功率放大器谐波理论而设计。在1 920~1 980 MHz频段和电源电压3.4 V条件下,测得常温状态该功率放大器增益为27 d B;输出功率在28 d Bm时功率附加效率达到42%,邻信道功率比为?36 d Bc;在?20℃~80℃之间功率附加效率和邻信道功率比基本不变。展开更多
In medical diagnosis, the problem of class imbalance is popular. Though there are abundant unlabeled data, it is very difficult and expensive to get labeled ones. In this paper, an ensemble-based active learning algor...In medical diagnosis, the problem of class imbalance is popular. Though there are abundant unlabeled data, it is very difficult and expensive to get labeled ones. In this paper, an ensemble-based active learning algorithm is proposed to address the class imbalance problem. The artificial data are created according to the distribution of the training dataset to make the ensemble diverse, and the random subspace re-sampling method is used to reduce the data dimension. In selecting member classifiers based on misclassification cost estimation, the minority class is assigned with higher weights for misclassification costs, while each testing sample has a variable penalty factor to induce the ensemble to correct current error. In our experiments with UCI disease datasets, instead of classification accuracy, F-value and G-means are used as the evaluation rule. Compared with other ensemble methods, our method shows best performance, and needs less labeled samples.展开更多
This paper aims to explore the benefits of Technology-Enhanced Learning(TEL)to better engage undergraduate students in college English classes in China.By experimenting with Wen Juanxing,an online questionnaire platfo...This paper aims to explore the benefits of Technology-Enhanced Learning(TEL)to better engage undergraduate students in college English classes in China.By experimenting with Wen Juanxing,an online questionnaire platform,it has been found that through the employment of“Classroom Response Systems”(hereafter CRS)such as Wen Juanxing(hereaftter WJX),college students’classroom participation and interaction can be significantly increased.Their learning outcome and efficiency can also be greatly improved.展开更多
文摘针对无线通信应用的射频功率放大器,提出了一种新颖的温度补偿电路。应用该温度补偿电路,设计了一款基于In Ga P/Ga As HBT工艺的两级F类功率放大器。该功率放大器采用了带温度补偿特性的有源偏置电路,能有效地提高线性度,补偿温度引起的性能偏差;输出匹配网络采用F类功率放大器谐波理论而设计。在1 920~1 980 MHz频段和电源电压3.4 V条件下,测得常温状态该功率放大器增益为27 d B;输出功率在28 d Bm时功率附加效率达到42%,邻信道功率比为?36 d Bc;在?20℃~80℃之间功率附加效率和邻信道功率比基本不变。
文摘In medical diagnosis, the problem of class imbalance is popular. Though there are abundant unlabeled data, it is very difficult and expensive to get labeled ones. In this paper, an ensemble-based active learning algorithm is proposed to address the class imbalance problem. The artificial data are created according to the distribution of the training dataset to make the ensemble diverse, and the random subspace re-sampling method is used to reduce the data dimension. In selecting member classifiers based on misclassification cost estimation, the minority class is assigned with higher weights for misclassification costs, while each testing sample has a variable penalty factor to induce the ensemble to correct current error. In our experiments with UCI disease datasets, instead of classification accuracy, F-value and G-means are used as the evaluation rule. Compared with other ensemble methods, our method shows best performance, and needs less labeled samples.
文摘This paper aims to explore the benefits of Technology-Enhanced Learning(TEL)to better engage undergraduate students in college English classes in China.By experimenting with Wen Juanxing,an online questionnaire platform,it has been found that through the employment of“Classroom Response Systems”(hereafter CRS)such as Wen Juanxing(hereaftter WJX),college students’classroom participation and interaction can be significantly increased.Their learning outcome and efficiency can also be greatly improved.
