fix: set example models to eval mode and follow the convention

[zewenli98]

Description

• In some examples, models are not set to eval mode, which was addressed in this PR.
• Follow the convention of the order .cuda().half().eval()

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas and hacks
• I have made corresponding changes to the documentation
• I have added tests to verify my fix or my feature
• New and existing unit tests pass locally with my changes
• I have added the relevant labels to my PR in so that relevant reviewers are notified