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This research has shown the need for a comprehensive understanding of correlations between geometry , additive manufacturing processing conditions , defect generation , and microstructure for characterization of complex components such as those designed by topology optimization .
 research, geometry, additive manufacturing, defect, microstructure, components, as, designed, topology optimization
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:
 research, geometry, additive manufacturing, defect, microstructure, components, as, designed, topology optimization