Abstract.A system of nested dichotomies is a hierarchical decomposition of a multi-class problem with c classes into c − 1 two-class problems and can be represented as a tree structure. Ensembles of randomlygenerated nested dichotomies have proven to be an effective approach to multi-class learning problems [1]. However, sampling trees by giving each tree equal probability means that the depth of a tree is limited only by the number of classes, and very unbalanced trees can negatively affect runtime. In this paper we investigate two approaches to building balanced nested dichotomies-class-balanced nested dichotomies and data-balanced nested dichotomies-and evaluate them in the same ensemble setting. Using C4.5 decision trees as the base models, we show that both approaches can reduce runtime with little or no effect on accuracy, especially on problems with many classes. We also investigate the effect of caching models when building ensembles of nested dichotomies.
The DC busbar is an important component for the ITER PF converter module to connect the converter and the reactor. This paper analyzes different cross-sections and different thermodynamic properties under natural-cooling and water-cooling conditions, and simulation is carried out by the software of the finite element method (FEM). The result of the analysis shows that the water-cooling method is the better choice for the DC busbar.
The design of high current balance reactors used in the ITER DC testing platform is presented, which is verified by simulations with finite element method software, and the reactors are fabricated and tested according to the design output. These reactors are chosen as multilayer multi-turn structure and cooled by water. The multilayer multi-turn structure is usually selected by some high voltage reactors, but is seldom used in high current situations. The analysis and testing results indicate that the multilayer multi-turn structure is also feasible for high current reactors with many advantages, and is of considerable significance to similar applications.
The development of electrical automation engineering control system is the foundation of modern industrial development in China, and also an important embodiment of the rapid development of modern technology. The application of electric automation technology can not only improve work efficiency, but also reduce enterprise cost. Based on this, the current situation and development trend of electrical automation engineering control system are studied for reference by relevant staff.
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