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A volume heat source model is used for laser/powder interaction considering the material absorption coefficients , while a surface heat source is used to consider the high laser energy absorption by dense metal alloys .
 concept or principle: volume; concept or principle: heat source; material: material; concept or principle: absorption; concept or principle: surface; concept or principle: heat source; concept or principle: laser energy; concept or principle: absorption; material: metal alloys
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: volume, heat source, material, absorption, surface, heat source, laser energy, absorption, metal alloys 
Answer:
 concept or principle: volume; concept or principle: heat source; material: material; concept or principle: absorption; concept or principle: surface; concept or principle: heat source; concept or principle: laser energy; concept or principle: absorption; material: metal alloys