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Still , these preliminary investigations indicate that the HYB-AM process , upon further optimization , has the potential of processing high quality aluminum alloy components .
 concept or principle: process; concept or principle: optimization; concept or principle: quality; material: aluminum alloy
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:
 concept or principle: process; concept or principle: optimization; concept or principle: quality; material: aluminum alloy