# My Research

## Estimating Parameter Spaces only from Time-Series data

(Reconstructing Bifurcation Diagram)

I estimate parameter spaces of unknown systems only from time-series data sets.
In the estimated parameter space, bifurcation diagrams that are similar original bifurcation diagrams can be reconstructed.
In addition, I analyze the estimated parameter space.
In this research, parameter dimension and values are unknown, and time-series data sets generated by a system with different values are only used.
Figure 1 shows an outline of this research.

In 1994, Tokunaga et al. proposed a method for reconstructing bifurcation diagrams [1].
By reconstructing the bifurcation diagrams, I can estimate oscillatory patterns when parameters are changed.
In addition, if dynamics of the system can be analyzed, I expect that the system can be controlled and predicted.

Figure 1 : Outline of this research.

[1] Tokunaga et al., Reconstructing bifurcation diagrams only from time-waveforms, Physica D, No.79, 1994

### What is the bifurcation diagram？

Figure 2 shows the bifurcation diagram. I see changes of time-series data from this figure. Here, Figure 2 is the bifurcation diagram of an one-dimensional system. Therefore, horizontal and vertical axises are parameter and state values, respectively.

Figure 2 : Bifurcation diagrams.

### What is the reconstruction of bifurcation diagrams？

The bifurcation diagram is reconstructed only from time-series data. Here, the target system is unknown.

Figure 3 : Reconstruction of bifurcation diagrams.