Equipment and supplies Design and construction 410 Testing 401 Measurement 210 Space vehicles 191 Maintenance and repair 185 Sound 172 more ... Purification 160 Safety measures 159 Nuclear power plants 154 Air conditioning 152 Radio 138 Heating 136 Materials 131 Photography 128 Telecommunication 125 History 118 Standards 113 Recording and reproducing 110 Chemical plants 109 Air 105 Airplanes 101 Chemical engineering 94 Wireless communication systems 94 Ventilation 92 Evaluation 89 Coal mines and mining 88 Costs 85 Petroleum industry and trade 79 Reliability 78 less ...