1. _optimization.tex has been added
2. new figure for _intro.tex has been added
3. Some editing in _reviews.tex file

TODO:
1. Continue the previous todo list
1. results2.tex has been renamed to results.tex
2. the old results.tex has been removed
Figures for optimization test case has been added.
1. _conclusion.tex has been added but not updated
2. _intro.tex has been finished including numerical table.
   However, the numerical table need to be redone. Maybe by
   constructing table.
3. _results.tex has been updated with optimization part but need to
   be edited.
4. uvlm.tex and _reviews.tex are ignored.
5. _uvlmmodel.tex has been edited, but need more works.

TODO:
1. Redo _conclusion.tex
2. Editing and grammar check