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Defects in WAAM can occur for various reasons , such as poor programming strategy , unstable weld pool dynamics due to poor parameter setup , thermal deformation associated with heat accumulation , environmental influence and other machine malfunctions .
 concept or principle: Defects; manufacturing process: WAAM; material: as; concept or principle: weld pool; concept or principle: parameter; process characterization: thermal deformation; machanical property: heat accumulation; machine or equipment: machine
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: Defects; manufacturing process: WAAM; material: as; concept or principle: weld pool; concept or principle: parameter; process characterization: thermal deformation; machanical property: heat accumulation; machine or equipment: machine