1973
This work investigates the feasibility of using acoustic emission for quality monitoring and combines a sensitive acoustic emission sensor with machine learning .
 concept or principle: investigates; concept or principle: feasibility; concept or principle: acoustic emission; concept or principle: quality; concept or principle: acoustic emission; machine or equipment: machine
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: investigates, feasibility, acoustic emission, quality, acoustic emission, machine 
Answer:
 concept or principle: investigates; concept or principle: feasibility; concept or principle: acoustic emission; concept or principle: quality; concept or principle: acoustic emission; machine or equipment: machine