To force Aster Export to treat your table and schema names in a case-sensitive manner, you must surround the schema and table names in double quote marks when you invoke ncluster_export. To pass a double quote mark to Aster Export, you must prefix it with the escape character, which is a backslash. That means you type a double quote mark like so: \".
To do this, surround the entire schemaname.tablename string in a single pair of double quotation marks.
For example, assuming you want to export to table "t" in schema "S", then you would invoke Aster Export in this form:
ncluster_export.exe -h 10.51.3.100 -U mjones -w st4g0l33 \"S\".\"t\" mydata.txt