In recent years, the increasing prevalence of hate speech in social media has been considered as a serious problem worldwide. Many governments and organizations have made significant investment in hate speech detection techniques, which have also attracted the attention of the scientific community. Although plenty of literature focusing on this issue is available, it remains difficult to assess the performances of each proposed method, as each has its own advantages and disadvantages. A general way to improve the overall results of classification by fusing the various classifiers results is a meaningful attempt. We first focus on several famous machine learning methods for text classification such as Embeddings from Language Models (ELMo), Bidirectional Encoder Representation from Transformers (BERT) and Convolutional Neural Network (CNN), and apply these methods to the data sets of the SemEval 2019 Task 5. We then adopt some fusion strategies to combine the classifiers to improve the overall classification performance. The results show that the accuracy and F1-score of the classification are significantly improved.

AltBOC(15,10) is the baseline of COMPASS B2 signal modulation. It is a BOC-like signal having different PN codes in the lower and the upper main split lobes, which allow one signal service per lobe. The two lobes can be received and processed separately like two BPSK(10) signals, or coherently processed to achieve better performance. Interoperability among COMPASS B2, Galileo E5 and GPS L5 is also achievable using AltBOC modulation. However, Galileo's 4-code AltBOC has drawbacks such as low efficiency and great receiver complexity. This paper presents a new modulation type named TD-AltBOC (Time Division AltBOC). The signal generation scheme and receiving method are presented, and are compared with AltBOC in the areas of power spectrum, ranging accuracy, anti-multipath performance, anti-interference performance, processing flexibility and complexity. Analysis results show TD-AltBOC has similar spectrum characteristics, interoperability, flexibility and anti-interference performance with AltBOC. When the frontend bandwidth is more than 50 MHz, TD-AltBOC can achieve better ranging accuracy and anti-multipath performance. It also has such advantages as high efficiency and low receiver complexity. TD-AltBOC could be a good solution to COMPASS B2 navigation signal.

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