Recognition of transportation modes can be used in different applications including human behavior research, transport management and traffic control. Previous work on transportation mode recognition has often relied on using multiple sensors or matching Geographic Information System (GIS) information, which is not possible in many cases. In this paper, an approach based on ensemble learning is proposed to infer hybrid transportation modes using only Global Position System (GPS) data. First, in order to distinguish between different transportation modes, we used a statistical method to generate global features and extract several local features from sub-trajectories after trajectory segmentation, before these features were combined in the classification stage. Second, to obtain a better performance, we used tree-based ensemble models (Random Forest, Gradient Boosting Decision Tree, and XGBoost) instead of traditional methods (K-Nearest Neighbor, Decision Tree, and Support Vector Machines) to classify the different transportation modes. The experiment results on the later have shown the efficacy of our proposed approach. Among them, the XGBoost model produced the best performance with a classification accuracy of 90.77% obtained on the GEOLIFE dataset, and we used a tree-based ensemble method to ensure accurate feature selection to reduce the model complexity.

The sheet beam klystron (SBK) is a new kind of microwave vacuum devices, which uses a high aspect ratio, thin rectangular beam to reduce space charge effects, increase power capability and beam-wave interaction efficiency. In this paper, an SBK cavity was studied and the resonant frequency, quality-factor and shunt impedance were computed. The theoretical formulae and 3D PIC simulation code were respectively used to find out the relation between gap voltage and input power, and the results of two methods were compared.

This paper describes a new numerical method based on the boundary element method (BEM) for the field computation of waveguide loaded high order mode output cavity (HMOC). A computer program is developed and the resonant frequency, external Q value and field distribution of a TM₂₁₀ HMOC are computed. The results agree well with those of ISFEL3D.