**5. Conclusions**

In this study, the advantages of the transition network and the bubble entropy were integrated based on the CPE method, and a new method to measure the coupling strength of two time series was proposed from the perspective of a cross-transition network. It was further used to build complex networks using the multichannel EEG recordings for cognitive load assessment. The results of the unidirectional coupled Honen model showed that this proposed method was not only suitable for the analysis of coupling strength between two short time series, but also had the advantages of being less affected by nonlinear parameters and sensitive to a weak coupling relationship. In addition, the proposed CBTN showed better performance in differentiating cognitive load than the CPE. The new method can be used for state evaluation based on multichannel physiological signals, such as brain state monitoring, quantitative evaluation of various types of mental diseases, and motion decoding based on multichannel electromyography (EMG). It also has an application potential in the financial research field.

**Author Contributions:** Conceptualization, X.C. and G.X.; methodology, X.C.; software, X.C. and X.Z.; validation, S.Z. and Z.T.; formal analysis, X.C.; investigation, X.C.; resources, S.Z.; data curation, X.C.; writing—original draft preparation, X.C.; writing—review and editing, X.C. and G.X.; visualization, X.Z.; supervision, G.X.; project administration, S.Z.; funding acquisition, S.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Scientific and Technological Innovation 2030, grant number: 2021ZD0204300 and the Xi'an City Innovation Capability Strengthening Basic Disciplines plan, grant number: 21RGSF0018 and the Key Projects in Shaanxi Province, grant number: 2021GXLH-Z-008).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation, to any qualified researcher.

**Acknowledgments:** We would like to thank all collaborators for their selfless help and guidance in research.

**Conflicts of Interest:** The authors declare no conflict of interest.
