1071
Higher gradient of Fe might cause the greater change of Fe I ( 407.84 nm ) Accurate on-line weld defect detection in robotic arc welding manufacturing is still challenging , due to the complexity and diversity of weld defects .
 material: Fe; material: Fe; process characterization: Accurate; engineering feature: weld; concept or principle: defect; manufacturing process: arc welding; concept or principle: complexity; engineering feature: weld; concept or principle: defects
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:
 material: Fe; material: Fe; process characterization: Accurate; engineering feature: weld; concept or principle: defect; manufacturing process: arc welding; concept or principle: complexity; engineering feature: weld; concept or principle: defects