whenxuan: create the notebook for nstemd and online emd

Author: wwhenxuan

README.md

@@ -103,6 +103,8 @@ plot_IMFs(signal, IMFs)             # per-channel panels
 | [`TVF_EMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd/tvf_emd.py) (Time Varying Filter Based EMD) | [[paper]](https://www.sciencedirect.com/science/article/pii/S0165168417301135) |   [[code]](https://github.com/stfbnc/pytvfemd/tree/master)   | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/emd_variants/tfv_emd.ipynb) |
 | [`MEMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd/memd.py) (Multivariate Empirical Mode Decomposition) | [[paper]](https://royalsocietypublishing.org/doi/full/10.1098/rspa.2009.0502) | [[code]](https://www.mathworks.com/matlabcentral/fileexchange/71270-fast-and-adaptive-multivariate-and-multidimensional-emd) | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/memd/memd.ipynb) |
 | [`APITMEMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd/apitmemd.py) (Adaptive-Projection Intrinsically Transformed MEMD) | [[paper]](https://www.commsp.ee.ic.ac.uk/~mandic/research/EMD_Stuff/AH_VG_DL_DPM_APITMEMD_RSTA_2016.pdf) | [[code]](https://www.commsp.ee.ic.ac.uk/~mandic/research/emd.htm) | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/memd/apitmemd.ipynb) |
+| [`NSTEMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd/nstemd.py) (Nonuniformly Sampled Trivariate EMD) | [[paper]](https://ieeexplore.ieee.org/document/7178660) | [[code]](https://www.commsp.ee.ic.ac.uk/~mandic/research/emd.htm) | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/emd_variants/nstemd.ipynb) |
+| [`OnlineEMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd/online_emd.py) (Online Empirical Mode Decomposition) | [[paper]](https://ieeexplore.ieee.org/document/7952969) | [[code]](https://github.com/romain-fontugne/onlineEMD) | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/emd_variants/online_emd.ipynb) |
 | [`EMD2D`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd2d/emd2d.py) (Empirical Mode Decomposition 2D for images) |          [[paper]](http://aquador.vovve.net/IEMD/)           |           [[code]](http://aquador.vovve.net/IEMD/)           | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/image/emd2d.ipynb) |
 | [`BMEMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_emd2d/bmemd.py) (Bidimensional Multivariate Empirical Mode Decomposition) |   [[paper]](https://ieeexplore.ieee.org/document/8805082)    | [[code]](https://www.mathworks.com/matlabcentral/fileexchange/72343-bidimensional-multivariate-empirical-mode-decomposition?s_tid=FX_rc1_behav) | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/image/bmemd.ipynb) |
 | [`FAEMD`](https://github.com/wwhenxuan/PySDKit/blob/main/pysdkit/_faemd/faemd.py) (Fast and Adaptive EMD) |   [[paper]](https://ieeexplore.ieee.org/document/8447300)    | [[code]](https://www.mathworks.com/matlabcentral/fileexchange/71270-fast-and-adaptive-multivariate-and-multidimensional-emd) | [[notebook]](https://github.com/wwhenxuan/PySDKit/blob/main/examples/faemd/faemd.ipynb) |