分类: 物理学 >> 核物理学 提交时间: 2023-06-09
摘要: A diffraction-limited storage ring with a multi-bend achromat lattice suffers from a small dynamic aperture for conventional off-axis injection. Thus, a longitudinal on-axis injection scheme based on a new type of crab cavity is proposed in this paper. Particle tracking simulations were performed to study the disturbance of the stored beam and the motion of the injected beam during the injection process. The possibility of multi-bunch injections was discussed. In addition, the effect of the long-range wake field induced by the stored beam was analyzed. A C-band standing-wave crab cavity was designed and produced as requested, and its field distribution was measured. The corresponding results are consistent with the simulation results.
分类: 计算机科学 >> 计算机科学的集成理论 提交时间: 2022-11-18 合作期刊: 《数据智能(英文)》
摘要: Currently, as a basic task of military document information extraction, Named Entity Recognition (NER) for military documents has received great attention. In 2020, China Conference on Knowledge Graph and Semantic Computing (CCKS) and System Engineering Research Institute of Academy of Military Sciences (AMS) issued the NER task for test evaluation, which requires the recognition of four types of entities including Test Elements (TE), Performance Indicators (PI), System Components (SC) and Task Scenarios (TS). Due to the particularity and confidentiality of the military field, only 400 items of annotated data are provided by the organizer. In this paper, the task is regarded as a few-shot learning problem for NER, and a method based on BERT and two-level model fusion is proposed. Firstly, the proposed method is based on several basic models fine tuned by BERT on the training data. Then, a two-level fusion strategy applied to the prediction results of multiple basic models is proposed to alleviate the over-fitting problem. Finally, the labeling errors are eliminated by post-processing. This method achieves F1 score of 0.7203 on the test set of the evaluation task.