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In this paper , the results of two different wire based additive-layer-manufacturing systems are compared : in one system Ti-6Al4V is deposited by a Nd : YAG laser beam , in the other by an arc beam ( tungsten inert gas process ) .
 material: Nd : YAG; concept or principle: laser beam; concept or principle: arc; manufacturing process: tungsten inert gas; concept or principle: process
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: Nd : YAG; concept or principle: laser beam; concept or principle: arc; manufacturing process: tungsten inert gas; concept or principle: process