7755
Therefore , the cooling air velocity can be employed as an additional control parameter in 3D printing for a specified model .
 cooling, be, as, parameter, 3D printing, model
Please list all entity words in the text that fit the category. Output format is "word1, 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:
 cooling, be, as, parameter, 3D printing, model