2021
An example hereof is shown in 21 where the lattice is conformal to two opposing surfaces and the lattice density varies to allow denser lattice in areas where simulations show higher stress will be experienced .
 concept or principle: lattice; concept or principle: surfaces; engineering feature: lattice density; concept or principle: lattice; process parameter: areas; enabling technology: simulations; machanical property: stress; material: be
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: lattice; concept or principle: surfaces; engineering feature: lattice density; concept or principle: lattice; process parameter: areas; enabling technology: simulations; machanical property: stress; material: be