Perhaps you should try some spelling variations:
"defined network optimization algorithm" » "defined network optimization algorithms", "defined network optimisation algorithm", "defined network estimation algorithm"
"modified parameter approximation algorithms" » "modified parameters approximation algorithms"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified parameter approximation algorithms\") OR (\"defined network optimization algorithm\"))~".
• Removing quotes may allow a broader search: (( modified parameter approximation algorithms ) OR ( defined network optimization algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified parameter approximation algorithms") OR ("defined network optimization algorithm"))*.