Technology: general issues 53 History of engineering and technology 41 Thermal insulation 34 Research & information: general 19 Metal insulator boundaries 14 History of engineering & technology 11 Insulation 11 Electric insulators 10 Metals 9 Sound insulating materials 9 Topological insulators 9 Topology 9 Acoustic wave absorption 8 Metal insulator transition 8 Partial discharges 8 Energy conservation 7 Fibers 7 Energy utilization 6 Performance 6 Semiconductor insulator boundaries 6 Substrates 6 Thermal conductivity 6 Construction industry 5 Energy gap 5 Heat transfer 5 Insulated gate bipolar transistors (IGBT) 5 Insulation materials 5 MIM devices 5 Palm oil 5 Sound absorption 5