Perhaps you should try some spelling variations:
"modified channel optimisation algorithm" » "modified channel optimization algorithms", "modified channel estimation algorithm", "modified channel estimation algorithms"
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified channel optimisation algorithm") OR ("modified notion approximation algorithms"))~.
• Removing quotes may allow a broader search: (( modified channel optimisation algorithm ) or ( modified notion approximation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified channel optimisation algorithm") or ("modified notion approximation algorithms"))*.