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We investigated the surface finish potential of the proposed hydrodynamic cavitation abrasive finishing ( HCAF ) by varying the process parameters , namely , the hydrodynamic upstream and downstream fluid pressures , fluid temperature , abrasive concentration , and processing time .
 engineering feature: surface finish; concept or principle: cavitation; material: abrasive; concept or principle: process parameters; material: fluid; material: fluid; material: abrasive
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 engineering feature: surface finish; concept or principle: cavitation; material: abrasive; concept or principle: process parameters; material: fluid; material: fluid; material: abrasive