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The temperature gradient in the molten pool increased slightly ( from 1.03 × 104 to 1.07 × 104 °C/mm in the direction perpendicular to the scanning path ; from 1.21 × 104 to 1.28 × 104 °C/mm in the thickness direction ) when the scan speed was increased from 50 to 200 mm/s , but increased significantly ( from 1.29 × 104 to 8.24 × 104 °C/mm in the direction perpendicular to the scanning path ; from 1.53 × 104 to 9.84 × 104 °C/mm in the thickness direction ) when the laser power was increased from 100 to 200 W. The width and depth of the molten pool decreased ( width from 137.1 to 93.8 μm , depth from 64.2 to 38.5 μm ) when the scan speed was increased from 50 to 200 mm/s , but increased ( width from 71.2 to 141.4 μm , depth from 32.7 to 67.3 μm ) when the laser power was increased from 100 to 200 W. Experimental SLM of CP Ti powder was carried out under different laser processing conditions and the microstructure of SLM-produced parts was investigated to demonstrate the reliability of the physical model and simulation results .
 process parameter: temperature gradient; concept or principle: molten pool; concept or principle: scanning; process parameter: scan speed; concept or principle: scanning; process parameter: laser power; concept or principle: molten pool; process parameter: scan speed; process parameter: laser power; concept or principle: Experimental; material: Ti powder; concept or principle: laser processing; concept or principle: microstructure; process characterization: reliability; concept or principle: physical model; enabling technology: simulation
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: temperature gradient, molten pool, scanning, scan speed, scanning, laser power, molten pool, scan speed, laser power, Experimental, Ti powder, laser processing, microstructure, reliability, physical model, simulation 
Answer:
 process parameter: temperature gradient; concept or principle: molten pool; concept or principle: scanning; process parameter: scan speed; concept or principle: scanning; process parameter: laser power; concept or principle: molten pool; process parameter: scan speed; process parameter: laser power; concept or principle: Experimental; material: Ti powder; concept or principle: laser processing; concept or principle: microstructure; process characterization: reliability; concept or principle: physical model; enabling technology: simulation