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
Introduction In China, it is not uncommon for students to be treated as passive recipients in class. They are trained in this way from primary school. So by the time they enter college, not only are they accustomed to...Introduction In China, it is not uncommon for students to be treated as passive recipients in class. They are trained in this way from primary school. So by the time they enter college, not only are they accustomed to the role of submissive student following the lead of a dominant teacher, but they also quite welcome it, for they don’t have to take any initiative in class, they just wait to be filled with knowledge. Students’ hesitancy to participate actively in class comes not just from students themselves but also from some teachers, who stick to the force-feeding method because it is an easy way for them to conduct a class. So I started to try and change this situation. I designed a teaching plan in which I used different techniques to provide the students with lots of opportunities to be active participants in class. Some of the techniques used are described below.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Introduction In China, it is not uncommon for students to be treated as passive recipients in class. They are trained in this way from primary school. So by the time they enter college, not only are they accustomed to the role of submissive student following the lead of a dominant teacher, but they also quite welcome it, for they don’t have to take any initiative in class, they just wait to be filled with knowledge. Students’ hesitancy to participate actively in class comes not just from students themselves but also from some teachers, who stick to the force-feeding method because it is an easy way for them to conduct a class. So I started to try and change this situation. I designed a teaching plan in which I used different techniques to provide the students with lots of opportunities to be active participants in class. Some of the techniques used are described below.
