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The local microstructure control relies on having a detailed understanding of local melt pool physics ( e.g. , 3-D melt pool shape as well as spatial and temporal variations of thermal gradient ( G ) and solidification rate ( R ) ) .
 microstructure, melt pool, 3-D, as, as, variations, thermal gradient, solidification rate
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:
 microstructure, melt pool, 3-D, as, as, variations, thermal gradient, solidification rate